Method for manufacturing a package containing a hydrogel

Abstract

To eliminate problems such that fluctuation ranges of swell speed when gelatinizing water absorptive resin are largely different, and an aggregate of the water absorptive resin is created, which have had to be addressed conventionally when manufacturing water-containing gel from dried water absorptive resin to improve productivity of the water-containing gel, and provide a speedy and stable manufacturing method of packages.SOLUTION: A manufacturing method of packages including water-containing gel swells dried water absorptive resin by aqueous liquid whose temperature is controlled, and packages the obtained water-containing gel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a package containing a hydrogel in which a water-absorbing resin is swollen with an aqueous liquid.

Background Art

[0002] A water-absorbing resin (also known as a superabsorbent polymer, Superabsorbent Polymer, abbreviated as SAP) has a water-absorbing ability to absorb a large amount of liquid and is mainly used in sanitary materials such as disposable diapers, sanitary napkins, and incontinence pads. In recent years, by utilizing the high water-absorbing, moisture-retaining, and hygroscopic properties of water-absorbing resins, they are used in various applications such as greening water-retaining materials; slow-release gelling materials such as deodorant materials; civil engineering gelling materials (such as water-retaining materials for cement and H-shaped steel extraction materials); various water-stopping materials (for example, water-stopping materials for food, toys, sensors, cables, etc.) (for example, Non-Patent Documents 1, 2, etc.).

[0003] Superabsorbent resins are generally produced by drying a hydrogel obtained by crosslinking a monomer aqueous solution. The superabsorbent resin is also pulverized if necessary and used as a superabsorbent resin powder. For example, in end-consumer products such as commercially available disposable diapers and sanitary napkins, a dried superabsorbent resin powder is arranged for the purpose of absorbing liquids such as urine and blood. In recent years, as a new use of superabsorbent resins, an aqueous liquid containing water or additives (e.g., inorganic salts, aromatic components, antibacterial components, deodorant components, insect repellent components, coloring components, etc.) is absorbed by the dried superabsorbent resin and used in end-consumer products in the state of a hydrogel. As product forms using such hydrogels of superabsorbent resins, heat generating materials typified by chemical warmers (e.g., disposable warmers, etc.); cold insulating materials; deodorant materials; sustained release materials of drugs, etc. are known. For example, a chemical warmer contains a heat generating composition in which a mixture containing activated carbon, a water retention material, and an aqueous solution of an alkali metal salt (particularly high-concentration brine, e.g., 10% sodium chloride aqueous solution) is mixed with a metal powder (e.g., iron powder), and exhibits heat retention properties using the heat generated by the oxidation of the metal powder by air as a heat source. The above heat generating composition is enclosed in a breathable bag and has been widely used conventionally as a chemical warmer (specifically, a disposable warmer) or a heat retention material, such as a hot eye mask, a beauty mask, a foot warmer, etc. As described above, the heat generating composition such as a chemical warmer contains a water retention material, and a hydrogel in which an aqueous solution of an alkali metal salt is supported on a superabsorbent resin is used as the water retention material (e.g., Patent Documents 1 to 8). In Patent Documents 1 to 3 and 5, superabsorbent resins with optimized physical properties such as particle size, absorption ratio under pressure, absorption ratio, and residual monomer amount for chemical warmers have been proposed. In Patent Documents 6 to 8, specific cationic or nonionic crosslinked polymers have been proposed as superabsorbent resins for chemical warmers. In addition, in Patent Documents 9 and 10, superabsorbent resins suitable for sustained release materials such as chlorine dioxide have been proposed. In Patent Documents 11 to 13, superabsorbent resins suitable for cold insulating materials (another name: cold storage materials) using hydrogels have been proposed.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Patent Document 11

Patent Document 12

Patent Document 13

Summary of the Invention

Problems to be Solved by the Invention

[0006] Considering the quality and productivity of the final consumer products using the hydrogel as described above, it is required to use a water-absorbing resin with as uniform absorption magnification and absorption rate as possible. However, the water-absorbing resins conventionally manufactured are suitable for absorbing urine, blood, etc. required for sanitary materials such as disposable diapers, but are not necessarily suitable for preparing hydrogels containing aqueous liquids such as water and additives (e.g., inorganic salts, aromatic components, antibacterial components, deodorant components, insect repellent components, coloring components). Therefore, when manufacturing a hydrogel by adding an aqueous liquid to a water-absorbing resin, problems such as a large variation in the swelling rate of the water-absorbing resin and a large influence on the manufacturing conditions; the formation of aggregates (lumps) of the water-absorbing resin have occurred.

[0007] Even when using the water-absorbing resins described in Patent Documents 1 to 8 etc. in which the physical properties of the conventional water-absorbing resins are modified, when the water-absorbing resin is mixed with an aqueous alkali metal salt solution (especially a high-concentration aqueous alkali metal salt solution), the gelled particulate water-absorbing resins bind to each other to form aggregates, or the gelled water-absorbing resin adheres to the mixing container of the water-absorbing resin and the aqueous liquid, etc., and various manufacturing problems have occurred. That is, even when using a water-absorbing resin modified to have physical properties suitable for a predetermined use, the manufacturing problems have not been solved. Since such manufacturing problems occur during the production of the hydrogel, they have also been a problem in the production of cold insulating materials, deodorant materials, insect repellent materials, sustained release materials, etc. using the hydrogel.

[0008] Furthermore, as a result of the inventors' examination of the manufacturing problems of the hydrogel, it has been found that even when using water-absorbing resins with the same physical properties, the productivity of the hydrogel varies greatly depending on the season. That is, the swelling rate when gelling the water-absorbing resin is lower in winter than in summer, and it has been found that the time required for the water-absorbing resin to swell sufficiently after supplying the aqueous liquid is significantly different between winter and summer. Therefore, the conditions for manufacturing the hydrogel with good productivity are different between summer and winter even for water-absorbing resins with the same physical properties, and accordingly, it has been found that the productivity of the final consumer products such as chemical hand warmers using the hydrogel also decreases. Even for water-absorbing resins with the same basic physical properties (e.g., the same water absorption rate), other physical properties may vary slightly depending on the water-absorbing resin manufacturer from which they are purchased. Therefore, when purchasing water-absorbing resins from multiple manufacturers, the conditions for producing the water-containing gel differ depending on the water-absorbing resin being purchased, and it has been found that the productivity of final consumer products such as chemical heat packs using the water-containing gel also decreases accordingly.

[0009] Similar problems also occur in the manufacturing processes of other products that use water-containing gels, such as cold insulation materials, deodorizing materials, insect repellent materials, and sustained release materials, and these are common problems for products that use water-containing gels.

[0010] The present invention has been made in view of the above circumstances, and its object is to provide a method for manufacturing a package containing a water-containing gel, in which, when producing the water-containing gel from a dried water-absorbing resin, the variation range of the gelation time (swelling rate) when gelling the water-absorbing resin, which has been a problem conventionally, is greatly different; To solve problems such as the formation of aggregates of the water-absorbing resin, improve the productivity of the water-containing gel, and provide a method for manufacturing a package quickly and stably.

Means for Solving the Problems

[0011] The present invention that has solved the above problems has the following configuration.

[0012] [1] A method for manufacturing a package containing a water-containing gel, characterized by swelling a dried water-absorbing resin with a temperature-controlled aqueous liquid and packaging the obtained water-containing gel.

[0013] [2] The method for manufacturing a package containing a water-containing gel according to [1] above, wherein the temperature-controlled aqueous liquid is a heated aqueous liquid or a cooled aqueous liquid.

[0014] [3] The method for manufacturing a package containing a water-containing gel according to [1] or [2] above, wherein the temperature of the temperature-controlled aqueous liquid is 0 to 100°C.

[0015] [4] The temperature of the heated aqueous liquid is 30 to 50 °C, and the method for manufacturing the package containing the hydrogel according to [2] above.

[0016] [5] The temperature-controlled aqueous liquid contains a water-soluble and / or water-insoluble additive, and the method for manufacturing the package containing the hydrogel according to any one of [1] to [4] above.

[0017] [6] The additive is one or more selected from the group consisting of inorganic salts, aromatic components, antibacterial components, deodorant components, insect repellent components, and coloring components, and the method for manufacturing the package containing the hydrogel according to [5] above.

[0018] [7] Adjust the temperature of the aqueous liquid to adjust the absorption rate of the water-absorbing resin, and the method for manufacturing the package containing the hydrogel according to any one of [1] to [6] above.

[0019] [8] The temperature variation range of the aqueous liquid after temperature control from the start to the end of addition to the water-absorbing resin is within ±10 °C, and the method for manufacturing the package containing the hydrogel according to any one of [1] to [7] above.

[0020] [9] The dried water-absorbing resin has a free swelling index SAR (saline absorption rate) of 0.5 [g / g / s] or less, and the method for manufacturing the package containing the hydrogel according to any one of [1] to [8] above. However, SAR is measured by the method described in the examples of the specification and is defined by the time it takes for 1.00 g of the water-absorbing resin to absorb 20 g of a 0.9 wt% sodium chloride aqueous solution.

[0021]

[10] The package contains the hydrogel, organic powder, and / or inorganic powder, and the method for manufacturing the package containing the hydrogel according to any one of [1] to [9] above.

[0022]

[11] Use of a packaging body containing the hydrogel according to any one of [1] to

[10] above for one or more selected from the group consisting of a heat insulating material, a cold insulating material, a deodorizing material, an insect repellent material, and a slow release material of a drug.

Advantages of the Invention

[0023] According to the present invention, problems related to variations in the gelation time (swelling rate) of the water-absorbing resin and the formation of aggregates during the production of the hydrogel from the dried water-absorbing resin can be solved. Therefore, according to the present invention, the productivity of the hydrogel is improved, and the adhesion of the hydrogel to manufacturing equipment such as mixing containers can also be suppressed. Thus, using conventional water-absorbing resins and manufacturing equipment such as existing mixing devices, a packaging body containing the hydrogel can be manufactured simply, quickly, and stably.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0025] In the present invention, when manufacturing a package containing a hydrogel, a dried water-absorbing resin is swollen with a temperature-controlled aqueous liquid, and the obtained hydrogel is packaged, whereby the generation of aggregates and the adhesion of the hydrogel in the mixing container can be eliminated, and the hydrogel and the package containing the hydrogel can be stably manufactured. Such an effect is obtained by using a temperature-controlled aqueous liquid, because the gelation time (absorption rate) of the water-absorbing resin into the hydrogel can be controlled. The gelation time (absorption rate) of the water-absorbing resin into the hydrogel varies depending on the type of water-absorbing resin used, specifically the manufacturer and manufacturing conditions. Also, the absorption rate varies depending on the temperature at which the hydrogel is manufactured, specifically the temperature of the aqueous liquid, even for water-absorbing resins with the same physical properties. Therefore, even when using water-absorbing resins with the same physical properties, the absorption rate may vary depending on the season. Due to such variations in the absorption rate, even when manufacturing hydrogels under the same manufacturing conditions for water-absorbing resins with the same physical properties, the absorption rate of the hydrogel varies depending on the season, making it difficult to stably manufacture the hydrogel. Also, since the temperature changes moment by moment, it was impossible to stably ensure a sufficient absorption rate in industrial-scale production, resulting in the generation of aggregates and the adhesion of the hydrogel to containers. As a result of intensive studies by the present inventors on such problems, it was found that by adjusting the temperature of the aqueous liquid added so as to obtain an appropriate absorption rate according to the physical properties of the water-absorbing resin and the temperature, a hydrogel can be prepared at a stable absorption rate and the above problems can be solved, leading to the present invention. Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be appropriately modified and implemented without departing from the spirit of the present invention.

[0026] Water-absorbing resin The "water-absorbing resin" in the present invention means a water-swellable and water-insoluble polymer gelling material. Also, "water-swellable" means that the CRC (absorption magnification under non-pressure) (NWSP241.0.R2(15)) defined in Non-Patent Document 3 is 5 [g / g] or more, and "water-insoluble" means that the Ext (water-soluble content) (NWSP241.0.R2(15)) defined in Non-Patent Document 3 is 50% by weight or less.

[0027] The water-absorbing resin having the above characteristics can be appropriately designed and is not particularly limited. Examples of the water-absorbing resin include polyacrylic acid (salt)-based crosslinked polymers, hydrolyzates of starch-acrylonitrile graft polymers, starch-acrylic acid graft polymers, saponified products of vinyl acetate-acrylic acid ester copolymers, hydrolyzates of acrylonitrile copolymers or acrylamide copolymers or crosslinked products thereof, carboxyl group-containing crosslinked polyvinyl alcohol modified products, and crosslinked isobutylene-maleic anhydride copolymers. One of these may be used, or two or more thereof may be used in combination. Among these, a hydrophilic crosslinked polymer obtained by crosslinking a polymerizable unsaturated monomer having a carboxyl group is preferable. More preferably, it is a polyacrylic acid (salt)-based water-absorbing resin. "Polyacrylic acid (salt)" means a polymer that optionally contains a graft component such as starch or PVA and contains 10 mol% or more of acrylic acid and / or its salt (hereinafter referred to as "acrylic acid (salt)") as a repeating unit, particularly a polymer having the main component. "Main component" means that the content (usage amount) of acrylic acid (salt) is usually 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 90 to 100 mol%, and still more preferably substantially 100 mol% with respect to the total amount of monomers (excluding internal crosslinking agents) used in the polymerization. Further, the polyacrylate as a polymer is not limited to the form in which the total amount (100% by weight) is a polymer, and within the range of maintaining the above performance, a surface-crosslinked product or a composition containing additives may be used. It must contain a water-soluble salt, preferably a monovalent salt, more preferably an alkali metal salt or an ammonium salt, still more preferably an alkali metal salt, and particularly preferably a sodium salt. Further, it is not limited to the form in which the total amount (100% by weight) is a polymer, and within the range of maintaining the above performance, a surface-crosslinked product or a composition containing additives may be used.

[0028] The "dried water-absorbing resin" preferably has a value measured by changing the drying temperature to 180°C at the water content rate (NWSP230.0.R2(15)) of the water-absorbing resin defined in Non-Patent Document 3 of 20% by weight or less, more preferably 15% by weight or less. Further, the dried water-absorbing resin preferably has free-flowability. The free-flowability is a water-absorbing resin having a flow rate of 5 g / sec or more, and further 7 g / sec or more. The Flow-Rate means the flow-down rate of the water-absorbing resin and is defined in NWSP251.0.R2(15).

[0029] The dried water-absorbing resin exists in various known forms such as sheet form, fibrous form, powdery form, etc., preferably in powdery form or fibrous form, and more preferably in powdery form. In this specification, "water-absorbing resin" also includes these various forms.

[0030] In the present invention, various known water-absorbing resins can be used as the dried water-absorbing resin. For example, dried water-absorbing resins used for various applications such as sanitary materials, water retention materials, and water stop materials can be used, and any commercially available water-absorbing resins can be used.

[0031] The dried water-absorbing resin is preferably a water-absorbing resin that satisfies the above-mentioned predetermined water content rate and free-flowability. The water-absorbing resin is more preferably at least one selected from the group consisting of non-pressurized absorption magnification (CRC), particle size distribution (PSD), absorption magnification under pressure (AAP0.3), particle size distribution (PSD), and free swelling index (SAR: saline absorption rate), more preferably two or more, still more preferably three or more, and most preferably all satisfy the following physical property values.

[0032] [Absorption magnification under non-pressurized condition] (CRC) (defined in NWSP241.0.R2(15)) The absorption magnification under non-pressurized condition (CRC) of the dried water-absorbing resin of the present invention is usually 10 g / g or more. Preferably, it is 20 g / g or more, more preferably 25 g / g or more. There is no particular limitation on the upper limit, but usually about 100 g / g or about 50 g / g is sufficient. The water absorption ratio under non-pressure is preferably adjusted to be in the range of 25 to 50 g / g. Note that the absorption ratio under non-pressure can be adjusted to the above range by appropriately controlling the amount of cross-linking agent during polymerization and subsequent surface cross-linking (secondary cross-linking).

[0033] For example, in the production of a water-containing gel for a heat-generating material such as a chemical warmer, when the absorption ratio under non-pressure (CRC) of the water-absorbing resin in a 0.9% sodium chloride aqueous solution is low, abnormal swelling on the surface of the water-absorbing resin powder can be suppressed when producing a water-containing gel with a high-concentration salt water (for example, 10% sodium chloride aqueous solution), and the strength of the water-absorbing resin powder can be maintained. Therefore, even when the stirring force during mixing is applied, the formation of aggregates and lumps can be suppressed. The absorption ratio under non-pressure (CRC) is preferably 40 g / g or less, more preferably 35 g / g or less, still more preferably 32 g / g or less, and even more preferably 30 g / g or less. In order to sufficiently hold the aqueous liquid in the water-absorbing resin, it is, for example, 5 g / g or more, preferably 10 g / g or more, more preferably 15 g / g or more, and still more preferably 20 g / g or more.

[0034] Also, for example, in the production of a water-containing gel for a drug sustained-release material, the absorption ratio under non-pressure (CRC) of the water-absorbing resin in a 0.9% sodium chloride aqueous solution is preferably 50 g / g or less, more preferably 40 g / g or less, still more preferably 35 g / g or less, and even more preferably 30 g / g or less. In order to sufficiently hold the drug solution in the water-absorbing resin, it is, for example, 5 g / g or more, preferably 10 g / g or more, more preferably 15 g / g or more, and still more preferably 20 g / g or above. When the absorption ratio under non-pressure (CRC) is low, it is necessary to use a large amount of water-absorbing resin for a certain amount of drug solution. When the absorption ratio under non-pressure (CRC) is high, the water-absorbing resin that has absorbed the drug solution swells and becomes gel-like, inhibiting the movement of the unabsorbed drug solution, causing a so-called gel blocking phenomenon, and it may take a long time to absorb the drug solution.

[0035] [Particle Size Distribution](PSD) The weight average particle diameter (D50) of the dried water-absorbing resin of the present invention is preferably 250 μm or more, more preferably 280 μm or more, still more preferably 300 μm or more, and preferably 500 μm or less, more preferably 450 μm or less. Further, the fine water-absorbing resin particles passing through a sieve with an opening of 150 μm (JIS standard sieve) are preferably 0 to 25% by weight, more preferably 0 to 15% by weight, still more preferably 0 to 10% by weight with respect to the whole water-absorbing resin. Further, the larger particles (aggregates) that do not pass through a sieve with an opening of 850 μm or more (or 710 μm or more) (JIS standard sieve) are preferably as few as possible, and are preferably 0 to 3% by weight, more preferably 0 to 1% by weight, still more preferably 0% by weight with respect to the whole water-absorbing resin particles. Further, in the present invention, the proportion of particles having a particle diameter of 150 μm or more and less than 850 μm, and further the proportion of particles having a particle diameter of 150 μm or more and less than 710 μm are adjusted to preferably 80% by weight or more, more preferably 90% by weight or more (the upper limit is 100%) with respect to the whole water-absorbing resin particles. Further, the logarithmic standard deviation (σζ) of the particle size distribution is preferably 0.20 to 0.50, more preferably 0.25 to 0.50, still more preferably 0.25 to 0.45, and particularly preferably 0.30 to 0.40. These particle sizes can be measured by the same method as “(1) Average Particle Diameter and Distribution of Particle Diameter” described in lines 25 to 43 on page 7 of European Patent No. 0349240. The standard sieve (opening) used for particle size measurement may be appropriately added according to the particle size of the object. For example, it is desirable to add standard sieves with an opening of 710 μm, 600 μm, etc., and perform sieving so as to obtain the target average particle diameter.

[0036] [Absorption capacity under pressure] (AAP0.3) (specified in NWSP242.0.R2(15)) The absorption ratio under pressure (AAP0.3) of the dried water-absorbing resin of the present invention is the absorption ratio of 0.9 g of the water-absorbing resin when measured under a load condition of 2.06 kPa with respect to a 0.9% sodium chloride aqueous solution. From the viewpoint of suppressing the decrease in water absorption performance due to its own weight, the absorption ratio under pressure (AAP0.3) is preferably 15 g / g or more, more preferably 20 g / g or more, and still more preferably 22 g / g or more. Also, considering the balance with other physical properties, the absorption ratio under pressure (AAP) is preferably 40 g / g or less, more preferably 38 g / g or less, and still more preferably 35 g / g or less. The absorption ratio under pressure (AAP) can be improved by surface crosslinking after particle size control and can be adjusted by performing surface crosslinking until it falls within the above range.

[0037] [Saline absorption rate] SAR The saline absorption rate (SAR) of the water-absorbing resin is measured by the method described in the examples below and is defined by the time it takes for 1.00 g of the water-absorbing resin to absorb 20 g of a 0.9 wt% sodium chloride aqueous solution. The saline absorption rate (SAR) of the dried water-absorbing resin of the present invention is preferably 0.1 g / g / s or more, more preferably 0.2 g / g / s or more, still more preferably 0.25 g / g / s or more, and particularly preferably 0.30 g / g / s or more. The upper limit is not particularly limited, but is, for example, 1.00 g / g / s or less, preferably 0.50 g / g / s or less.

[0038] Hydrated gel The "hydrated gel" of the present invention refers to a state in which it swells with an aqueous liquid optionally containing an additive and has a swelling ratio (defined by CRC / swelling ratio in an aqueous liquid optionally containing an additive) of, for example, 5 times or more, preferably 10 times or more, and more preferably 15 times or more the self-weight of the dried water-absorbing resin. In the present invention, since a dried water-absorbing resin is used, the hydrated gel generated in the production process of the water-absorbing resin, for example, the hydrated gel obtained by polymerizing a monomer is not included in the hydrated gel of the present invention.

[0039] The water-containing gel of the present invention is prepared by swelling a dried water-absorbing resin with a temperature-controlled aqueous liquid. The aqueous liquid used for swelling the dried water-absorbing resin may be any liquid having the property of swelling the water-absorbing resin, preferably water, an aqueous solution, or a water slurry. The aqueous solution or water slurry may be an aqueous solution or an aqueous dispersion containing an additive component. Note that tap water, industrial water, or pure water can all be used as the water. In the present invention, components that exhibit a desired function may be added to the water-absorbing resin together with the aqueous liquid as additives. The additives can be appropriately selected from known materials according to various applications. The additives may be water-soluble or water-insoluble. Therefore, the water containing the additives may be an aqueous solution or an aqueous dispersion. The aqueous liquid preferably has water as the main component (50 to 100% by weight, more preferably 80 to 100% by weight) in order to obtain a water-containing gel with a desired swelling ratio. The additives are preferably one or more selected from the group consisting of inorganic salts, aromatic components, deodorizing components, antibacterial components, insect-proofing components, and coloring components, and more preferably additives having volatility in the use environment. The concentration of the additives in the aqueous liquid (the total concentration in the case of multiple additives, the same hereinafter) is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 50% by weight or less, and more preferably 20% by weight or less. In addition to the above additives, the water-containing gel of the present invention may appropriately contain an appropriate amount of other additives, such as surfactants, preservatives, antioxidants, ultraviolet absorbers, etc., as required. Also, in the case of oil-soluble additives or water-dispersible additives, etc., in order to adjust the solubility or dispersibility of the additives in the aqueous liquid, a solvent other than water, particularly a hydrophilic organic solvent that can be mixed with water (for example, a solvent with a solubility of 10 g of the hydrophilic solvent / 100 g of water (23 °C) or more, a polyhydric alcohol such as propylene glycol) may be used, and the hydrophilic organic solvent is also appropriately selected in the range of 50 to 0% by weight.

[0040] Examples of the inorganic salts include sodium chloride, potassium chloride, calcium chloride, magnesium chloride, ammonium chloride, calcium sulfate, magnesium sulfate, ammonium sulfate, sodium nitrate, potassium nitrate, sodium sulfate, sodium carbonate, etc.

[0041] Examples of the aromatic components include natural fragrances such as lavender, lemon, orange, jasmine, and peppermint; synthetic fragrances such as limonene, terpinolene, geraniol, citronellol, and ethyl acetate; and blended fragrances thereof.

[0042] Examples of the antibacterial and antifungal components include octyltrimethylammonium chloride, didecyldimethylammonium gluconate, chlorhexidine, chlorhexidine gluconate, and chlorites.

[0043] Examples of the deodorant components include extracts of plants such as polyphenol, rice, pine, hinoki, and bamboo; desalted betaine compounds; modified organic acid compounds; triethanolamine; stabilized chlorine dioxide; and aldehyde compounds.

[0044] Examples of the insect repellent components include hinokitiol, hiba oil, allyl isothiocyanate, propylene glycol monomethyl ether, ethanol, propanol, and 1,8-cineole.

[0045] Examples of the coloring components include known dyes and pigments having various hues such as blue, red, yellow, and green.

[0046] Temperature adjustment In the present invention, "temperature adjustment" means heating or cooling the temperature of the aqueous liquid before adding it to the dried water-absorbing resin to adjust it to a desired temperature. Therefore, the temperature-adjusted aqueous liquid is a heated aqueous liquid or a cooled aqueous liquid, and does not include an un-temperature-adjusted (e.g., room temperature) aqueous liquid. By using the temperature-adjusted aqueous liquid, the absorption rate of the water-absorbing resin can be adjusted, and the generation of aggregates and the adhesion of the water-containing gel can be suppressed. While adding the aqueous liquid to the water-absorbing resin, specifically, it is preferable that the temperature of the aqueous liquid is constant from the start to the end of the addition of the aqueous liquid.

[0047] In the present invention, it is possible to use water-absorbing resins that are mainly used as sanitary materials such as disposable diapers and water-absorbing resins that satisfy the above physical properties. Therefore, there are many water-absorbing resins designed to have an optimal absorption rate for aqueous liquids at temperatures near body temperature. When the aqueous liquid added to such a water-absorbing resin is cooled, the absorption rate of the water-absorbing resin decreases, and when heated, the absorption rate of the water-absorbing resin tends to increase. Also, when the manufacturing environment of the hydrogel is a low-temperature environment, such as in winter, for the absorption of the aqueous liquid at that temperature, the absorption rate of the water-absorbing resin decreases, resulting in problems such as time-consuming gelation, generation of aggregates, and adhesion of the hydrogel. Therefore, gelation can occur at a better absorption rate when adding a heated aqueous liquid than when adding an unregulated aqueous liquid, so the generation of aggregates can be suppressed. On the other hand, depending on the physical properties of the water-absorbing resin, the absorption rate for the unregulated aqueous liquid may be too fast. In such cases, by cooling the aqueous liquid to be added to reduce the absorption rate, a hydrogel with a uniform water content can be stably prepared compared to using the aqueous liquid before temperature adjustment. Thus, in the present invention, it is desirable to adjust the temperature of the aqueous liquid added according to the absorption rate of the water-absorbing resin. Also, as described above, the absorption rate of the water-absorbing resin is affected by the season, that is, the air temperature when preparing the hydrogel, particularly the ambient temperature. Therefore, even for water-absorbing resins with the same physical properties, the temperature of the aqueous liquid added may be adjusted according to the ambient temperature to control the absorption rate. In the present invention, it is preferable to adjust the temperature of the aqueous liquid to a temperature at which problems such as aggregates and adherents do not occur in consideration of the absorption rate of the water-absorbing resin and the ambient temperature, and then add it to the water-absorbing resin.

[0048] The temperature of the aqueous liquid after temperature adjustment is preferably within a range that does not exceed the freezing point or boiling point. The temperature of the temperature-adjusted aqueous liquid is preferably in the range of 0 to 100 °C. More preferably, the temperature adjustment is performed so that the temperature of the aqueous liquid after temperature adjustment is higher than that before temperature adjustment. For example, the temperature of the aqueous liquid after temperature adjustment is preferably adjusted to a temperature higher than the room temperature when producing the hydrogel, preferably 20 °C or higher, more preferably 30 °C or higher, still more preferably 35 °C or higher, and even more preferably 40 °C or higher. The upper limit varies depending on the decomposition temperature or volatilization temperature of the additives used as necessary. However, if the temperature of the aqueous liquid becomes too high, the physical properties of the hydrogel obtained may deteriorate depending on the type of water-absorbing resin, or the absorption rate may become too fast, making it difficult to produce a uniform hydrogel. Therefore, the temperature of the aqueous liquid after temperature adjustment is preferably 100 °C or lower, more preferably 90 °C or lower, still more preferably 80 °C or lower, and particularly preferably 50 °C or lower. When producing a hydrogel using a water-absorbing resin with the same physical properties, from the perspective of suppressing fluctuations in the physical properties of the hydrogel within a lot, it is desirable that the temperature of the aqueous liquid added to the water-absorbing resin be as uniform as possible. Therefore, during the period from the start to the end of the addition of the aqueous liquid, the variation in the temperature of the aqueous liquid after temperature adjustment is preferably as narrow as possible. Considering the change in the room temperature during hydrogel production that varies depending on the season and time zone, the variation range of the temperature of the aqueous liquid after temperature adjustment is preferably within ±10 °C, more preferably within ±8 °C, still more preferably within ±5 °C, and even more preferably within ±2 °C with respect to the set temperature of the aqueous liquid after temperature adjustment. For heating the aqueous liquid, various known heaters or heat exchangers for heating aqueous liquids can be used. Also, for cooling the aqueous liquid, various known aqueous liquid cooling devices or heat exchangers can be used.

[0049] In the present invention, a dried water-absorbing resin is swollen with an aqueous liquid adjusted to a predetermined temperature to prepare a hydrogel. The preparation of the hydrogel may be continuous or batchwise. Also, the addition order is not particularly limited, and any of the following can be adopted: adding the aqueous liquid to the water-absorbing resin in the mixing container; adding the water-absorbing resin to the aqueous liquid in the mixing container; adding the water-absorbing resin and the aqueous liquid to the mixing container simultaneously. If necessary, it may be added while stirring the inside of the mixing container. For mixing, various known mixing devices are It can be used. The mixing device is preferably a container-fixed mixing device, more preferably a mechanical stirring type mixing device. Examples of known mixing devices include a turbo mixer (manufactured by Hosokawa Micron Corporation), a Lodige mixer (manufactured by Lodige), a mortar mixer (manufactured by Nippon Giken Kikai Co., Ltd.), a planetary mixer, a Nauta mixer, and the like.

[0050] A package containing a hydrogel In the present invention, the "package" is a container that holds a hydrogel. For the package, various known soft materials and hard materials such as non-woven fabrics of natural fibers and chemical fibers; cloth; paper; leather; plastic; thermoplastic films such as polyethylene resin can be used. The flexibility and air permeability of the package can be appropriately selected according to the application. In the present invention, a hydrogel is packaged, and whether or not the package is sealed is not a concern. For example, when contact between the hydrogel and the outside air is required to achieve a desired effect, an opening may be provided in a part of the package to ensure air permeability. For example, in FIG. 1, the bottom surface and side surfaces of the package 1 are plastic containers without air permeability, and the ceiling surface is open as an opening, so that the hydrogel 2 stored inside can come into contact with the outside air. Also, even if the package does not have an opening, air permeability may be ensured by using a material with air permeability for the package or providing air holes in the package. For example, in FIG. 2, the packages 1a and 1b are made of non-woven fabrics with air permeability. After placing the hydrogel 2 on one side, the packages 1a and 1b may be overlapped and sealed to form a package 1 in which the hydrogel is sealed inside by crimping or the like. The package containing the hydrogel of the present invention includes not only the final product, that is, finished products such as a heating material; a cold insulation material; a deodorant; a sustained release material for a drug, but also an intermediate in the manufacturing process. Therefore, it is sufficient that the package contains at least a hydrogel. The package of the present invention is used as a package containing a hydrogel during actual use. However, in order to maintain the hydrogel state until actual use, it is preferably packaged in a non-volatile state. For example, the exterior is double-packaged with a non-volatile container or a non-volatile film, or at least the opening is sealed with a non-volatile film or the like and packaged so that it can be opened during actual use.

[0051] In addition to the water-containing gel, the package of the present invention may contain a third additive as needed. For example, it may contain one or more of organic powders and / or inorganic powders. Such powders include activated carbon, pulp, paper, wood powder, fiber waste, Ero It should be noted that the content of "エロ" is inappropriate and may not be suitable for patent text or general formal translation scenarios. It is recommended to ensure the suitability and propriety of the content to be translated. aluminum, silica gel, alumina, diatomaceous earth, clay, zeolite, radiolite, bentonite, montmorillonite, activated clay, talc, etc. are exemplified. The particle size of the powder can be appropriately selected according to the use, and the average particle size (D50) of the powder is preferably 0.1 μm to 10 mm. Also, the content of the powder can be appropriately selected according to the use, for example, it is 0.1 to 100 parts by weight with respect to 100 parts by weight of the composition in the package.

[0052] The package containing the water-containing gel of the present invention can be used for various purposes. For example, the package containing the water-containing gel can be used for one or more selected from the group consisting of a heat generating material, a cold insulating material, a deodorizing material, an insect repellent material, and a sustained release material of a drug. Also, by appropriately combining the types of additives and the organic powders and / or inorganic powders added as needed, it can be used as a heat generating material, a cold insulating material, a deodorizing material, an insect repellent material, a sustained release material of a drug, etc., and the package containing the water-containing gel can have multiple functions depending on the combination of additives and the like.

[0053] As an example of the use, a chemical warmer using the package containing the water-containing gel of the present invention will be described. The chemical warmer contains activated carbon and a water-containing gel swollen with an aqueous solution of an alkali metal salt, and more preferably contains a metal powder and the like.

[0054] Activated carbon supplies oxygen to the metal powder, and various known activated carbons can be used. For example, activated carbon powder prepared from various known raw materials such as coconut shells, wood, coal, petroleum pitch, and resins can be used. Of course, various commercially available activated carbon powders can also be used.

[0055] The aqueous alkali metal salt solution is an aqueous liquid containing a chloride of an alkali metal that has a catalytic action to promote the oxidation of metal powder. The aqueous alkali metal solution is preferably an aqueous sodium chloride solution, an aqueous lithium chloride solution, or an aqueous potassium chloride solution, and more preferably an aqueous sodium chloride solution. The concentration is not particularly limited, but the higher the concentration, the higher the catalytic effect. Therefore, the concentration is preferably 1% or more, more preferably 3% or more, and still more preferably 5% or more, and is preferably less than the saturation concentration at the use temperature, more preferably 30% or less, and still more preferably 20% or less of a high-concentration brine. For example, an aqueous sodium chloride solution with a concentration of 1% or more can be used as the aqueous alkali metal salt solution. The metal powder is not particularly limited as long as it is a metal that generates heat by oxidation, and various known metal powders such as iron powder and aluminum powder can be used.

[0056] The water-absorbing resin is a carrier for holding the aqueous alkali metal salt solution. It may be various water-absorbing resins conventionally used in applications such as sanitary materials, or a water-absorbing resin whose physical properties have been modified for use as a heat storage material. Preferably, a water-absorbing resin that satisfies the above physical properties is used. Preferably, it is a powdery water-absorbing resin. When producing a hydrogel by holding an aqueous alkali metal salt solution in such a water-absorbing resin, the higher the concentration of the aqueous alkali metal salt solution, the more difficult it is to be absorbed by the water-absorbing resin and the longer it takes to gel. In such a case, the absorption rate can be adjusted by using a temperature-controlled aqueous alkali metal solution. Specifically, it is preferable to adjust the temperature of the aqueous alkali metal salt solution added according to the gelation time of the water-absorbing resin.

Examples

[0057] Hereinafter, the invention will be described according to examples, but the present invention is not limited to and should not be construed as being limited to the examples. Also, the physical properties described in the claims and examples of the present invention were determined according to the EDANA method and the following measurement methods under the conditions of room temperature (20 to 25 ° C) and humidity of 50 RH% unless otherwise specified. Furthermore, the electrical equipment presented in the examples and comparative examples used a power supply of 200 V or 100 V and 60 Hz. For convenience, "liter" may be abbreviated as "L" and "weight%" may be abbreviated as "wt%".

[0058] (a) Weight average particle diameter (D50) The measurement of the weight average particle diameter (D50) of the dried water-absorbing resin of the present invention was carried out according to the measurement method described in European Patent No. 0349240 with reference to Japanese Patent Application Laid-Open No. 2000-302876 and Pamphlet of International Publication No. 2011 / 126079.

[0059] (b) Absorption ratio under no pressure (CRC) The measurement of CRC of the dried water-absorbing resin of the present invention was carried out in accordance with NWSP241.0.R2(15).

[0060] (c) Absorption ratio under pressure (AAP0.3) The measurement of AAP0.3 of the dried water-absorbing resin of the present invention was carried out in accordance with NWSP242.0.R2(15).

[0061] (d) Swelling index of free swell (SAR) The measurement of the swelling index of free swell (SAR) of the dried water-absorbing resin of the present invention was carried out as follows. 1.00 g of the water-absorbing resin was placed in a 25 mL glass beaker (diameter 32 - 34 mm, height 50 mm). At this time, the upper surface of the water-absorbing resin placed in the beaker was made horizontal. If necessary, the surface of the water-absorbing resin may be made horizontal by taking measures such as gently tapping the beaker. Next, 20.0 g of a 0.9 mass% sodium chloride aqueous solution adjusted to 23°C ± 0.2°C was weighed into a 50 mL glass beaker. The weighed 0.9 mass% sodium chloride aqueous solution was carefully and quickly poured into the 25 mL beaker containing the water-absorbing resin. Simultaneously with the contact of the poured 0.9 mass% sodium chloride aqueous solution with the water-absorbing resin, the measurement of time was started and the measurement of time was terminated when the upper surface of the 0.9 mass% sodium chloride aqueous solution in the beaker into which the 0.9 mass% sodium chloride aqueous solution was poured was visually observed at an angle of about 20° and the upper surface, which was originally the surface of the 0.9 mass% sodium chloride aqueous solution, was replaced by the surface of the water-absorbing resin that had absorbed the 0.9 mass% sodium chloride aqueous solution due to the absorption of the 0.9 mass% sodium chloride aqueous solution by the water-absorbing resin (time ts [seconds]). The SAR was determined according to the following formula. SAR [g / g / s] = 20.0 / (ts [seconds] × 1.00) ··· Formula (1)

[0062] [Production Example of Water Absorbent Resin] (Production Example 1) 1.588 parts by mass of trimethylolpropane triacrylate as an internal crosslinking agent was dissolved in 4970.2 parts by mass of a 38% by mass aqueous solution of sodium acrylate (neutralization rate: 75 mol%) as a monomer component to obtain a reaction solution. Next, this reaction solution was degassed for 30 minutes under a nitrogen gas atmosphere. Subsequently, the reaction solution was supplied to a reactor equipped with a lid, a stainless steel double-bowl kneader with a jacket having an internal volume of 10 L and two sigma blades. While maintaining the reaction solution at 30°C, the inside of the reactor was purged with nitrogen gas. Subsequently, while stirring the reaction solution, 17.2 parts by mass of a 15% by mass aqueous solution of sodium persulfate and 10.3 parts by mass of a 0.1% by mass aqueous solution of L-ascorbic acid were each made into an aqueous solution and added. Polymerization started approximately 1 minute later. After the start of polymerization, the peak temperature was reached in about 20 minutes. Thereafter, while continuing stirring, a particulate water-containing gel-like polymer was taken out 60 minutes after the start of polymerization. The obtained water-containing gel-like polymer was spread on a stainless steel wire mesh with an opening size of 850 μm and dried with hot air at 180°C for 45 minutes. Next, the dried product was pulverized using a roll mill (WML type roll crusher / manufactured by Inoguchi Giken Co., Ltd.), and further classified with JIS standard sieves having an opening size of 850 μm and 150 μm to obtain an amorphous crushed resin (base polymer) (1) having an average particle size of 442 μm. Next, 0.5 part by mass of glycerin, 0.5 part by mass of isopropyl alcohol, and 2 parts by mass of ion-exchanged water as a surface crosslinking agent were mixed with 100 parts by mass of the base polymer (1) using a stirring mixer. Thereafter, the mixture was heat-treated at 195°C for 30 minutes to obtain a surface-crosslinked water absorbent resin (1). To this surface-crosslinked water-absorbing resin (1), hydrophilic silica (manufactured by Tokuyama; Rheoseal-QS20) was added and mixed so that the addition amount was 0.3% by mass to obtain water-absorbing resin (1). The weight-average particle diameter (D50) of the water-absorbing resin (1) was 436 μm, the absorption ratio under non-pressurized conditions (CRC) was 35 g / g, the absorption ratio under pressurized conditions (AAP0.3) was 27 g / g, and the free swelling index (SAR) was 0.38 g / g / s.

[0063] (Production Example 2) 6.986 parts by mass of trimethylolpropane triacrylate as an internal crosslinking agent was dissolved in 4962.7 parts by mass of a 38% by mass aqueous solution of sodium acrylate (neutralization rate: 75 mol%) as a monomer component to obtain a reaction solution. The same polymerization, drying, pulverization, and classification process operations as in Production Example 1 were performed to obtain an amorphous crushed resin (base polymer) (2) with an average particle diameter of 809 μm. The obtained base polymer (2) was used as water-absorbing resin (2) as it was. Next, this reaction solution was degassed for 30 minutes in a nitrogen gas atmosphere. The absorption ratio under non-pressurized conditions (CRC) of the water-absorbing resin (2) was 27 g / g, the absorption ratio under pressurized conditions (AAP0.3) was 26 g / g, and the free swelling index (SAR) was 0.14 g / g / s.

[0064] (Production Example 3) The above water-absorbing resin (1) was classified (JIS standard sieve: 300 μm), and the fraction less than 300 μm of the JIS standard sieve was used as the water-absorbing resin (3) of the present application. The absorption ratio under non-pressurized conditions (CRC) of the water-absorbing resin (3) was 29 g / g, the absorption ratio under pressurized conditions (AAP0.3) was 22 g / g, and the free swelling index ( SAR) was 0.95 g / g / s.

[0065] [Production Example of Hydrated Gel Composition for Chemical Cylinders] (Production of Hydrated Gel) 10 parts of a water-absorbing resin was placed in a 250 mL plastic container, and while standing, 10 parts of a 10% by mass aqueous sodium chloride solution was poured in all at once. After pouring the 10% aqueous sodium chloride solution, the time until the water-absorbing resin completely absorbed the liquid was measured (hereinafter sometimes referred to as the gelation time).

[0066] (Preparation of the hydrogel composition for chemical hand warmer) Separate from the measurement of the gelation time in the production of the above hydrogel, the hydrogel composition for chemical hand warmer was prepared. In the same manner as in the production of the above hydrogel, 10 parts of an aqueous 10% by mass sodium chloride solution was poured all at once into 10 parts of a water-absorbing resin placed in a plastic container. Two minutes after the addition of the 10% sodium chloride aqueous solution, all of the hydrogel was transferred to a SUS container with a volume of 500 mL, and 40 parts by mass of activated carbon (manufactured by Fumura Chemical Co., Ltd.; product name: Taiko activated carbon P) was further added. Immediately, it was mixed at 200 rpm for 2 minutes with a three-wing motor having two stirring blades (length 1.3 cm × width 7 cm), and then the SUS container was inverted up and down, and the bottom of the container was tapped 10 times from above at 10 times per second to take out the internal preparation material.

[0067] (Adhesion evaluation) The adhesion amount of the preparation material remaining in the container was examined, and the adhesion was evaluated according to the following criteria. Adhesion ratio of the preparation material [%] = Adhesion amount [g] / Total mass of the charged materials [g] × 100% 〇: Adhesion ratio is 20% or less △: Adhesion ratio is more than 20% and less than 50% ×: Adhesion ratio is 50% or more

[0068] Comparative Example 1 A hydrogel composition for chemical hand warmer was produced using the water-absorbing resin (1), and the gelation time was measured. At that time, the laboratory was adjusted to the temperature shown in Table 1. Similarly, the hydrogel composition for chemical hand warmer was prepared, and the adhesion was evaluated. The results are shown in Table 1. (Comparative Example 1-1) Room temperature 23.6 °C Uncontrolled temperature of the 10% by mass sodium chloride aqueous solution at the room temperature: 24.1 °C (Comparative Example 1-2) Room temperature 5.0 °C Uncontrolled temperature of the 10% by mass sodium chloride aqueous solution at the room temperature: 5.0 °C

[0069] (Gelation time in the production of the hydrogel) Comparative Example 1-1: 2 minutes 15 seconds Comparative Example 1-2: 5 minutes 22 seconds

[0070] (Evaluation) In Comparative Example 1-1 and Comparative Example 1-2, it took 2 minutes and 15 seconds and 5 minutes and 22 seconds, respectively, to produce the hydrogel. From these results, it is presumed that it is difficult to stably produce the kairo in winter when the temperature is low and the production time of the hydrogel becomes long. Also, since the same water-absorbing resin was used in both Comparative Example 1-1 and Comparative Example 1-2, it was found that the hydrogel production time is affected by the temperature of the sodium chloride aqueous solution added. After producing the hydrogel, when evaluating the production process up to the preparation of the hydrogel composition for chemical kairo, in both Comparative Example 1-1 and Comparative Example 1-2, a sodium chloride aqueous solution that was not absorbed by the water-absorbing resin remained in the container at the time of adding the activated carbon, and particularly in Comparative Example 1-2, the remaining amount was large. Comparative In Comparative Example 1-1, when activated carbon was added and mixed, the occurrence of adhesion was recognized in the adhesion evaluation. In Comparative Example 1-2, since the remaining amount of the sodium chloride aqueous solution was even larger, when activated carbon was added and mixed, it became slurry-like, and a large amount of adhesion was recognized in the adhesion evaluation.

[0071] (Example 1) The gelation time was measured in the same manner as in Comparative Example 1-1 and Comparative Example 1-2, except that the temperature of the 10% by mass sodium chloride aqueous solution added was adjusted to 30 °C (±1 °C).

[0072] (Example 1-1) Room temperature 23.6 °C Temperature of the 10% by mass sodium chloride aqueous solution after temperature adjustment at this room temperature: 29.6 °C

[0073] (Example 1-2) Room temperature 5.0 °C Temperature of the 10% by mass sodium chloride aqueous solution after temperature adjustment at this room temperature: 30.0 °C

[0074] (Gelation time in hydrogel production) Example 1-1: 1 minute and 51 seconds Example 1-2: 1 minute and 58 seconds

[0075] (Example 2) The gelling time was measured in the same manner as in Example 1-1, except that the temperature of the 10% by mass aqueous sodium chloride solution introduced was adjusted to 45 °C (±1 °C) before introduction. Room temperature: 23.6 °C Temperature of the 10% by mass aqueous sodium chloride solution after temperature adjustment at the room temperature: 45.0 °C

[0076] (Gelling time in the production of the hydrogel) 1 minute and 02 seconds

[0077] (Example 3) The gelling time was measured in the same manner as in Example 2, except that the water-absorbing resin (1) was changed to the water-absorbing resin (2). Room temperature: 23.6 °C Temperature of the 10% by mass aqueous sodium chloride solution after temperature adjustment at the room temperature: 44.1 °C

[0078] (Gelling time in the production of the hydrogel) 1 minute and 48 seconds

[0079] (Example 4) A hydrogel was produced in the same manner as in Example 1-1, except that the water-absorbing resin (1) was changed to the water-absorbing resin (2). Room temperature: 23.6 °C Temperature of the 10% by mass aqueous sodium chloride solution after temperature adjustment at the room temperature: 29.5 °C

[0080] (Gelling time in the production of the hydrogel) 48 seconds

[0081] (Example 5) The temperature of the 10% by weight aqueous sodium chloride solution introduced was adjusted to 15 °C (±1 °C) before introduction and then introduced. The hydrogel production time was measured in the same manner as in Example 4. Room temperature: 23.6 °C Temperature of the 10% by weight aqueous sodium chloride solution after temperature adjustment at the room temperature: 15.2 °C

[0082] (Gelation time in the production of the water-containing gel) 1 minute and 38 seconds

[0083] [Table 1]

[0084] (Evaluation) In each of the tests of Examples 1 to 5 using temperature-controlled water or an aqueous sodium chloride solution, gelation could be achieved stably and in a short time. Also, from these results, it is presumed that by adjusting the temperature of the aqueous liquid to be added, stable production of the kairo can be achieved regardless of the ambient temperature. When evaluating the production process from the production of the water-containing gel to the kairo preparation material, in each of Examples 1 to 5, no aqueous sodium chloride solution that was not absorbed by the water-absorbing resin remained in the container at the time of adding the activated carbon, and no aggregates were observed. As a result, uniform mixing of the activated carbon and the water-containing gel was possible. Also, the adhesiveness after mixing was good. Also, from the comparison between Comparative Example 1-1 (gelation time: 2 minutes and 15 seconds at room temperature of 23.6°C) and Comparative Example 1-2 (the same: 5 minutes and 22 seconds at room temperature of 5.0°C), and Examples 1-1 (the same: 1 minute and 51 seconds at room temperature of 23.6°C) and Example 1-2 (the same: 1 minute and 58 seconds at room temperature of 5.0°C), it can be seen that the production method of the present invention can stably produce a package containing a water-containing gel with high productivity regardless of temperature changes due to seasons, day or night.

[0085] In Example 3, a water-absorbing resin with a slower absorption rate than that of Example 1 was used, but it was found that stable production could be achieved by using a heated aqueous liquid. In Examples 4 and 5, water-absorbing resins with a faster absorption rate than that of Example 1 were used. In Example 4, the absorption rate was very fast and gelation was possible, but a very small part of the water-absorbing resin tended to form lumps. On the other hand, in Example 5, by adjusting the temperature of the aqueous liquid to be lower than that of Example 4, the absorption rate could be adjusted and stable production could be achieved.

[0086] Examples 6 to 9, Comparative Example 2 Preparation of the chemical solution sustained-release material After inserting 5 g of the water-absorbing resin shown in Table 2 into a plastic container (inner volume: 100 mL) with an open ceiling as shown in Fig. 1, 80 g of a sustained-release component-containing liquid (aqueous solution composed of 2.42 parts by weight of sodium chlorite (manufactured by Kanto Chemical Co., Inc.), 0.32 parts by weight of sodium dihydrogen phosphate anhydrous (manufactured by Wako Pure Chemical Industries, Ltd.), and 97.26 parts by weight of ion-exchanged water) was added to the container and left for 1 minute. The sustained-release component-containing liquid was added all at once with the plastic container in a stationary state. After 1 minute had elapsed, the state of the water-containing gel in the container was visually confirmed and evaluated according to the following criteria. In Examples 6 to 9, the temperature of the sustained-release component-containing liquid was adjusted to the temperature shown in Table 2 and then added.

[0087] Evaluation Criteria 〇: Gelation is complete and no unabsorbed chemical solution remains in the container. △: Unabsorbed chemical solution remains in the container and there is a water-containing gel in which gelation is not complete. ×: A large amount of unabsorbed chemical solution remains in the container and the chemical solution and the gel are completely separated.

[0088]

Table 2

[0089] Comparing Example 6 and Comparative Example 2, even though the room temperature was the same, Comparative Example 2-1, in which the temperature of the added sustained-release component-containing liquid was not adjusted, had a slow absorption rate, and in particular, in Comparative Example 2-2, where the temperature of the sustained-release component-containing liquid was low, the water-absorbing resin hardly absorbed the chemical solution. On the other hand, in Example 6, the temperature of the sustained-release component-containing liquid was increased and supplied. As a result, the absorption rate of the water-absorbing resin increased and gelation could be achieved in a short time. The same tendency was also confirmed in Example 7. Examples 8 and 9 are examples using water-absorbing resins with a high absorption rate. In Example 8, the absorption rate was very high and gelation could be achieved, but a very small part of the water-absorbing resin tended to form lumps. On the other hand, in Example 9, by adjusting the absorption rate by lowering the temperature of the added sustained-release component-containing liquid, a water-containing gel could be produced quickly and stably.

[0090] (Summary) In the production of a package containing a water-containing gel obtained by swelling a dried water-absorbing resin with an aqueous liquid, by using an aqueous liquid whose temperature has been adjusted for gelation of the water-absorbing resin, as shown in Examples 1 to 9, regardless of seasonal or day-night temperature changes or the type of water-absorbing resin (for example, use of different water-absorbing resins in multiple purchases), it is possible to provide a method for producing a package containing a water-containing gel that is rapid and stable by swelling the water-absorbing resin into water-containing gel particles stably and rapidly.

Explanation of Signs

[0091] 1 Package 1a One component constituting the package 1b The other component constituting the package 2 Water-containing gel 3 Sealing part

Claims

1. A method for producing a package containing a hydrogel, comprising the steps of: swelling a dried water-absorbent resin with an aqueous alkali metal salt solution having a concentration of 5% by weight or more and adjusted to a temperature of 20° C. or higher; and packaging the obtained hydrogel; The weight average particle diameter (D50) of the dried water absorbent resin is 250 μm or more and 500 μm or less, Particles of the dried water absorbent resin passing through a sieve having an opening of 150 μm are 0 to 25% by weight based on the total weight of the dried water absorbent resin, The dried water absorbent resin has a CRC (specified in NWSP241.0.R2(15)) of 20 g / g or more and 35 g / g or less in a 0.9% sodium chloride aqueous solution, and an AAP0.3 (specified in NWSP242.0.R2(15)) of 22 g / g or more in a 0.9% sodium chloride aqueous solution; The package contains the hydrous gel, activated carbon, and metal powder.

2. A method for manufacturing a packaging body as described in claim 1, wherein the packaging body is for a thermal material.

3. A method for manufacturing the packaging body described in claim 1, wherein the packaging body is for a chemical hand warmer.

4. A method for manufacturing a packaging body as described in claim 1, wherein the CRC of the dried absorbent resin is 32 g / g or more.

5. A method for producing a packaging body as described in claim 1, wherein the alkali metal salt aqueous solution is a sodium chloride aqueous solution.

6. A method for producing a packaging body as described in claim 1, wherein the hydrous gel is swelled by the alkali metal salt aqueous solution to more than five times the weight of the dried water-absorbent resin.

7. Use of a packaging body obtained by the method for manufacturing a packaging body described in any one of claims 1 to 6 as a thermal material.

8. Use of a packaging material obtained by the method for producing a packaging material described in any one of claims 1 to 6 in a chemical hand warmer.

Images