Moisture Absorbent and Device

Abstract

To provide: a moisture absorbent which has low metal corrosivity; and a device which uses the moisture absorbent.SOLUTION: This moisture absorbent contains a salt composed of a specific cyclic quaternary cation and a phosphate ester anion and / or a specific dicationic quaternary ammonium cation and a phosphate ester anion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a moisture absorbent and an apparatus. In particular, it relates to a moisture absorbent used in apparatuses such as air conditioners and absorption refrigerators.

Background Art

[0002] In a desiccant type air conditioner, a liquid moisture absorbent having the property of absorbing water vapor in the air is used. For example, Non-Patent Documents 1 to 2 disclose liquid moisture absorbents using aqueous lithium chloride solution, aqueous calcium chloride solution, and triethylene glycol. Further, Patent Documents 1 to 5 and Non-Patent Documents 3 to 7 disclose liquid moisture absorbents using ionic liquids. Furthermore, as the above ionic liquids, salts of bromide anions and tetrafluoroborate, dimethyl phosphate anions, methyl sulfate anions with imidazolium cations, alkylphosphonium cations, and quaternary ammonium cations are disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 7

Non-Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0005] The lithium chloride aqueous solution and calcium chloride aqueous solution disclosed in Non-Patent Documents 1 to 2 have the advantage of being able to stably obtain low-humidity air. However, generally, these aqueous solutions of alkali metal halide ions and alkaline earth metal halide ions are corrosive to metals. Therefore, when these substances are applied to a moisture absorbent, there is a problem that a highly corrosion-resistant metal such as titanium must be used for the part of the moisture absorbent in devices such as air conditioners and absorption refrigerators that comes into contact with the moisture absorbent. In addition, the moisture absorbents disclosed in Patent Documents 1 to 5 and Non-Patent Documents 4 to 5 use bromide anions and tetrafluoroborate anions as ionic liquids composed of imidazolium cations and constituent anions. Bromide anions and tetrafluoroborate anions have problems in that they are corrosive to metals and also have toxicity, making them difficult to handle. Patent Document 5 reports that an ionic liquid composed of cholinium cation and lactate anion has high hygroscopicity, but lactate anion is unstable and cannot withstand long-term use. Non-Patent Document 3 reports that the hygroscopicity of imidazolium ionic liquids mainly depends on the anion, and also reports that acetate anion has good water absorption. However, only imidazolium cations have been studied for the cation, and it is known that aqueous solutions of imidazolium ionic liquids have high corrosivity to metals such as copper (Non-Patent Document 7). In addition, it is known that ionic liquids with acetate anions are unstable and cannot withstand long-term use. In order to solve such problems, Non-Patent Papers 7 and 8 focus on anions such as dimethylphosphoric acid and methylsulfuric acid for the selection of ionic liquids. Non-Patent Document 7 reveals that an ionic liquid composed of a combination of phosphonium cation and dimethylphosphate ester anion exhibits excellent hygroscopicity. Non-Patent Document 8 reports that an aqueous solution of an ionic liquid composed of a combination of cholinium cation and dimethylphosphate ester anion has high hygroscopicity and the lowest metal corrosivity among the reported humidity-regulating ionic liquids in the past. In addition, Patent Document 6 discloses a moisture absorbent excellent in metal corrosion resistance using phosphonium cations. However, higher hygroscopic performance has been demanded regarding hygroscopicity. The present invention aims to solve such problems, and aims to provide a moisture absorbent exhibiting metal corrosion resistance and good moisture absorption, and an apparatus using the same.

Means for Solving the Problems

[0006] As a result of investigations by the present inventors under the above problems, it has been found that the above problems can be solved by using a moisture absorbent containing a salt composed of an ammonium ion having a specific structure and a phosphate ester anion. Specifically, the above problems have been solved by the following means. <1>A moisture absorbent containing a salt composed of an ammonium cation represented by formula (1) and / or an ammonium cation represented by formula (2), and a phosphate ester anion.

Chemical formula

Chemical formula

Chemical formula

Advantages of the Invention

[0007] According to the present invention, it has become possible to provide a moisture absorbent exhibiting good metal corrosion resistance and good moisture absorption, and an apparatus using the same.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0009] Hereinafter, the embodiments for carrying out the present invention will be described in detail. Note that the following embodiments are examples for explaining the present invention, and the present invention is not limited to only these embodiments. In this specification, "~" is used in the sense of including the numerical values described before and after it as the lower limit value and the upper limit value. In this specification, various physical property values and characteristic values are those at 23°C unless otherwise specified. In the notation of groups (atomic groups) in this specification, a notation that does not indicate substitution or non-substitution includes both a group (atomic group) having no substituent and a group (atomic group) having a substituent together with the group (atomic group) having no substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, a notation that does not indicate substitution or non-substitution preferably means unsubstituted. When the standards shown in this specification differ depending on the year and the measurement methods, etc., they are based on the standards as of January 1, 2021 unless otherwise specified.

[0010] The moisture absorbent of this embodiment is characterized by containing a salt composed of an ammonium cation represented by formula (1) and / or an ammonium cation represented by formula (2) and a phosphate ester anion.

Chemical formula

[0011] By adopting such a configuration, a moisture absorbent that exhibits metal corrosion resistance and good moisture absorption is obtained. That is, it has been found that by using a salt composed of an ammonium cation (preferably a quaternary ammonium cation) having a predetermined structure and a phosphate ester anion, low metal corrosiveness and good moisture absorption can be obtained.

[0012] <The ammonium cation represented by formula (1)> One of the ammonium cations used in this embodiment is the ammonium cation represented by formula (1). [Chemical formula] (In formula (1), R 11 and R 12 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, or a poly(alkylene ether) group having 10 or fewer carbon atoms. However, at least one of R 11 and R 12 is not a hydrogen atom. n1 and m1 are each independently an integer from 1 to 6. X 11 is an oxygen atom, -N(R 13 )- (wherein R 13 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), or an alkylene group having 1 to 3 carbon atoms.)

[0013] In formula (1), R 11 and R 12 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, or a poly(alkylene ether) group having 10 or fewer carbon atoms, and an alkyl group having 1 to 6 carbon atoms and a hydroxyalkyl group having 1 to 6 carbon atoms are preferred, an alkyl group having 1 to 3 carbon atoms and a hydroxyalkyl group having 1 to 3 carbon atoms are more preferred, and an alkyl group having 1 or 2 carbon atoms and a hydroxyalkyl group having 1 or 2 carbon atoms are even more preferred. Also, at least one of R 11 and R 12 is not a hydrogen atom, but both are not hydrogen atoms, that is, it is preferably a quaternary ammonium cation.

[0014] In formula (1), n1 and m1 are each independently an integer from 1 to 6, preferably an integer from 1 to 3, more preferably 1 or 2, and even more preferably 2. Also, the ammonium cation represented by formula (1) is preferably a 5-membered ring or a 6-membered ring, and more preferably a 6-membered ring.

[0015] In formula (1), X 11 is an oxygen atom, -N(R 13 ), or an alkylene group having 1 to 3 carbon atoms, preferably an oxygen atom or an alkylene group having 1 to 3 carbon atoms, more preferably an oxygen atom or a methylene group. R 13 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom.

[0016] The ammonium cation represented by formula (1) preferably contains the ammonium cation represented by formula (1-1).

Chemical formula

[0017] The molecular weight of the ammonium cation represented by formula (1) is preferably 72 to 450.

[0018] Examples of the ammonium cation represented by formula (1) are shown below. Needless to say, the ammonium cation in this embodiment is not limited to these.

Chemical formula

[0019] <The ammonium cation represented by formula (2)> One of the ammonium cations used in this embodiment is the ammonium cation represented by formula (2). [Chemical formula] (In formula (2), R 21 ~R 26 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, or a poly(alkylene ether) group having 10 or fewer carbon atoms. However, at least one of R 21 ~R 23 and at least one of R 24 ~R 26 is not a hydrogen atom. Two of R 21 ~R 23 and two of R 24 ~R 26 may be bonded to each other to form a ring. n2 and m2 are each independently an integer of 1 to 6. X 2 is a single bond, an oxygen atom, -N(R 27 )- (where R 27 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), an alkylene group having 1 to 3 carbon atoms, or an alkyleneoxy group having 1 to 3 carbon atoms).)

[0020] In formula (2), R 21 ~R 26 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, or a poly(alkylene ether) group having 10 or fewer carbon atoms, an alkyl group having 1 to 6 carbon atoms and a hydroxyalkyl group having 1 to 6 carbon atoms are preferred, an alkyl group having 1 to 6 carbon atoms is more preferred, an alkyl group having 1 to 3 carbon atoms is even more preferred, and a methyl group or an ethyl group is more preferred. In formula (2), R 21 ~R 23at least one of and R 24 ~R 26 At least one of them is not a hydrogen atom, and none of them is a hydrogen atom, that is, it is preferably a quaternary ammonium cation. In formula (2), R 21 ~R 23 Two of and R 24 ~R 26 Two of them may be bonded to each other to form a ring. In this embodiment, R 21 ~R 23 Two of and / or R 24 ~R 26 When two of them are bonded to each other to form a ring, R 21 ~R 23 And R 24 ~R 26 Are each preferably a ring formed by bonding an alkyl group having 1 to 6 carbon atoms and a hydroxyalkyl group having 1 to 6 carbon atoms (for example, the ring shown in the exemplary compound (11) described later) and an alkyl group having 1 to 6 carbon atoms. The ring at this time is preferably a 5-membered ring or a 6-membered ring, and more preferably a 6-membered ring.

[0021] In formula (2), n2 and m2 are each independently an integer of 1 to 6, preferably an integer of 1 to 3, and more preferably 1 or 2. In formula (2), X 2 Is a single bond, an oxygen atom, -N(R 27 )(provided that R 27 Is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), an alkylene group having 1 to 3 carbon atoms, or an alkyleneoxy group having 1 to 3 carbon atoms, and is preferably a single bond, an oxygen atom, and an alkylene group having 1 to 3 carbon atoms, preferably a single bond, an oxygen atom, a methylene group, an ethylene group, an n-propylene group, and a 1,1-dimethylmethylene group, and more preferably a single bond, an oxygen atom, a methylene group and an ethylene group. In the present embodiment, the number of atoms constituting the chain connecting the nitrogen atoms constituting the two ammonium cations in formula (2) is preferably 2 to 8, more preferably 2 to 6. By setting the range in this way, the hygroscopicity tends to be further improved. Here, the number of atoms constituting the chain connecting the nitrogen atoms is two in the exemplified compound (7) described later and three in the exemplified compound (8).

[0022] The ammonium cation represented by formula (2) more preferably contains the ammonium cation represented by formula (2-1) and / or the ammonium cation represented by formula (2-2).

Chemical formula

Chemical formula

[0023] The molecular weight of the ammonium cation represented by formula (2) is preferably 76 to 450.

[0024] Examples of the ammonium cation represented by formula (2) are shown below. Needless to say, the ammonium cation in the present embodiment is not limited to these.

Chemical formula

Chemical formula

[0025] <Phosphate ester anion> The phosphate ester anion used in the present embodiment is not particularly defined in terms of its type or the like as long as it can form a salt with the ammonium cation represented by formula (1) and / or the ammonium cation represented by formula (2).

[0026] In the present embodiment, it is preferable that the phosphate ester anion is an anion represented by formula (3). By using such a phosphate ester anion, a stable salt can be formed with the ammonium cation of formula (1) or formula (2), and the generation of odor can be effectively suppressed.

Chemical formula

[0027] In formula (3), R 31 is a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a poly(alkyleneoxy) group having 10 or less carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or a poly(alkylthio) group having 10 or less carbon atoms, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are preferable, an alkoxy group having 1 to 6 carbon atoms is more preferable, an alkoxy group having 1 to 3 carbon atoms is even more preferable, and a methoxy group and an ethoxy group are even more preferable. In formula (3), R 32 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a poly(alkyleneoxy) group having 10 or less carbon atoms, an alkylthio group having 1 to 6 carbon atoms, or a poly(alkylthio) group having 10 or less carbon atoms, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are preferable, an alkoxy group having 1 to 6 carbon atoms is more preferable, an alkoxy group having 1 to 3 carbon atoms is even more preferable, and a methoxy group and an ethoxy group are even more preferable.

[0028] The molecular weight of the phosphate ester used in this embodiment is preferably 64 to 650.

[0029] Examples of the phosphate ester anions used in the present embodiment are shown below. Needless to say, the phosphate ester anions in the present embodiment are not limited to these. [Chemical formula] [Chemical formula]

[0030] <Ammonium phosphate> As described above, the moisture absorbent of the present embodiment contains a salt composed of an ammonium cation represented by formula (1) and / or an ammonium cation represented by formula (2) and a phosphate ester anion. Examples of the salts contained in the moisture absorbent of the present embodiment are shown below. Needless to say, the present invention is not limited to these. In the examples described later, the salt of the following (18) is referred to as "specific salt (18)". The same applies to other salts hereinafter. [Chemical formula]

[0031] [Chemical formula]

[0032] The above salts can be synthesized, for example, by subjecting a tertiary amine to an onium reaction with a trialkyl phosphate ester. Since this synthesis process allows the reaction to proceed easily, the specific salt can be synthesized extremely simply. In the present embodiment, since no metal exchange reaction or anion exchange using an ion exchange resin is required, the incorporation of halogens that cause corrosion can be suppressed. In the case of the ammonium cation represented by formula (2), the salt may be composed of one type of phosphate ester anion or two types of phosphate ester anions.

[0033] The formula weight of the salt is preferably 136 or more, and preferably 1100 or less.

[0034] The salt preferably has a low viscosity. Specifically, when the salt is an 80% by mass aqueous solution, the viscosity at 35 °C is preferably 150 cP or less. The ideal viscosity of the lower limit is 0, but even if it is 30 cP or more, it sufficiently satisfies the required performance.

[0035] <Desiccant> The desiccant of the present embodiment contains one or more salts composed of an ammonium cation represented by formula (1) and / or an ammonium cation represented by formula (2) and a phosphate ester anion.

[0036] In particular, in the present embodiment, the salt is preferably an ionic liquid. An ionic liquid means a substance having a melting point of 100 °C or less at 1 atm. In particular, the desiccant of the present embodiment is preferably liquid at least in the range of 0 to 5 °C. The desiccant of the present embodiment may be an aqueous solution, and is preferably an aqueous solution. In this case, the specific salt is contained in the form of the above cation and the above anion. The amount of water is preferably 10% by mass or more and preferably 95% by mass or less with respect to the total amount of the salt (ionic liquid) and water. Furthermore, the desiccant of the present embodiment may further contain other components usually used in desiccants within a range that does not inhibit the effects of the present invention.

[0037] The desiccant of the present embodiment can be used in devices such as air conditioners and absorption refrigerators. As examples of such devices, the descriptions in JP-A-2006-142121, JP-A-2018-144029, JP-A-2020-30004, etc. can be referred to. In particular, since the generation of odors is suppressed, it is particularly suitable for open-system applications such as desiccant-type air conditioners. The moisture absorbent of the present embodiment can be preferably applied to, for example, a desiccant type air conditioner or an absorption chiller. Note that the moisture absorbent of the present embodiment can be used in both open and closed systems. However, when used in an open system, from the viewpoint of suppressing odors, a moisture absorbent in which the anion constituting the specific salt is the above phosphoric acid ester anion is particularly suitable.

Example

[0038] The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. When the measuring instruments etc. used in the examples are difficult to obtain due to being obsolete etc., measurements can be made using other devices having equivalent performance. Unless otherwise specified, this example was carried out in an environment of 23°C and a relative humidity of 40%.

[0039] Example 1: Synthesis of N-ethyl-N-methylmorpholinium diethyl phosphate (19)

Chemical formula

[0040] <Moisture Absorption Test> A petri dish dispensed with 0.9008 g of the specific salt (19) obtained above was placed together with a hygrometer (Illuminance, UV, Temperature, Humidity Data Logger TR - 74Ui manufactured by T&D Corporation) in a plastic bag with a capacity of 1,110 cm 3 equipped with a chuck (Ziplock (registered trademark), 273 mm × 268 mm, manufactured by Asahi Kasei Home Products Corporation), and the plastic bag was sealed. This was placed in a constant temperature bath at 30°C and left standing, and the humidity change inside the plastic bag until the humidity inside the plastic bag reached an equilibrium state was measured. The results are shown in Graph Figure 1. As shown in Figure 1, the humidity decreased over time, and it can be seen that the specific salt (19) of Example 1 has moisture absorption.

[0041] From the measurement results of the humidity change in the plastic bag, the moisture absorption rate and moisture absorption speed per mole of the specific salt (19) were calculated. Also, the moisture absorption rate and moisture absorption speed per gram of the specific salt (19) were calculated. The molar moisture absorption capacity is the value obtained by dividing the difference between the humidity at the start of the test and the humidity at the equilibrium state by the number of moles of the specific salt in Example 1 contained in 0.9008 g of the specific salt (19). The molar moisture absorption speed is the value obtained by dividing the time when the humidity in the plastic bag reaches the intermediate value between the humidity at the start of the test and the humidity at the equilibrium state by the above molar moisture absorption capacity per mole of the sample. It was also calculated per gram. The results are shown in Table 1.

[0042] Example 2: N 1 ,N 1 ,N 1 ,N 6 ,N 6 ,N 6 Synthesis of N,N'-hexamethylhexane-1,6-diaminium dimethyl phosphate (25)

Chemical formula

[0043] <Moisture Absorption Test> A petri dish containing 1.2349 g of the specific salt (25) obtained above was placed together with a hygrometer (T&D Corporation, Illuminance, Ultraviolet Ray, Temperature, Humidity Data Logger TR-74Ui) into a zip-lock bag with a capacity of 1,110 cm 3 manufactured by Asahi Kasei Home Products Corporation (Zip Lock (registered trademark), 273 mm × 268 mm), and the bag was sealed. This was placed in a constant temperature bath at 30°C and left standing, and the humidity change inside the bag until the humidity inside the bag reached an equilibrium state was measured. The results are shown in Graph Figure 2. As shown in Figure 2, the humidity decreased over time, and it can be seen that the specific salt (25) of Example 2 has moisture absorption properties. The molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate were calculated in the same manner as in Example 1. The results are shown in Table 1.

[0044] <Comparative Example 1> Commercially available calcium chloride for drying (manufactured by Nacalai Tesque, lot number M0A0090) was opened, 1.295 g was taken in a petri dish, and immediately, a moisture absorption test was conducted in the same manner as in Example 1, and the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate were calculated. The results are shown in Table 1 and Figure 3.

[0045] <Comparative Example 2> A commercially available blue granular silica gel (manufactured by FUJIFILM Wako Pure Chemical Corporation, lot number CTH225) was opened, and immediately, 1.1597 g was taken in a petri dish, and a moisture absorption test was conducted in the same manner as in Example 1 to calculate the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate. The results are shown in Table 1.

[0046] <Comparative Example 3> A commercially available lithium chloride (manufactured by FUJIFILM Wako Pure Chemical Corporation, lot number HPQ6248) was opened, 0.8749 g was taken in a petri dish, and immediately, a moisture absorption test was conducted in the same manner as in Example 1 to calculate the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate. The results are shown in Table 1.

[0047] <Comparative Example 4> 5.000 g of a 30% by mass aqueous solution of the above lithium chloride (manufactured by FUJIFILM Wako Pure Chemical Corporation, lot number HPQ6248) was taken in a petri dish, and a moisture absorption test was conducted in the same manner as in Example 1 to calculate the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate. The results are shown in Table 1.

[0048] <Comparative Example 5> Cholinium dimethyl phosphate ([Ch][DMPO4]) described in Non-Patent Document 8 was synthesized according to the literature, 1.000 g of [Ch][DMPO4] after vacuum drying was taken in a petri dish, and a moisture absorption test was conducted in the same manner as in Example 1 to calculate the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate. The results are shown in Table 1.

[0049]

Table 1

[0050] As shown in Table 1 above, Example 1 (specific salt (19)) and Example 2 (specific salt (25)) showed high molar moisture absorption capacity compared with Comparative Example 1 using calcium chloride, Comparative Example 2 using silica gel, and Comparative Example 3 using lithium chloride. Among the examples, Example 2 using the specific salt (25) showed higher molar moisture absorption capacity and molar moisture absorption rate. Compared with cholinium dimethyl phosphate ([Ch][DMPO4]) described in Non-Patent Document 8 shown in Comparative Example 5, Example 1 and Example 2 also showed high molar moisture absorption capacity.

[0051] Also, compared with the 30 mass% aqueous solution of lithium chloride (Comparative Example 4) currently used in humidity control air conditioners, Example 1 showed a moisture absorption capacity 190 times higher in terms of molar moisture absorption capacity, and Example 2 showed 350 times higher. In terms of the moisture absorption rate per mole, Example 1 showed a rate 100 times higher, and Example 2 showed 190 times higher.

[0052] <Example 3> Following Example 1, the above specific salts (18), (20), (21), and (22) were synthesized, and a moisture absorption test was conducted in the same manner as in Example 1 to calculate the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate. The results are shown in Table 2.

[0053]

Table 2

[0054] As shown in Table 2 above, it was also confirmed that the above specific salts (18), (20), (21), and (22) have good moisture absorption performance.

[0055] <Example 4> Following Example 2, the above specific salts (23), (24), (26), (27), (28), (29), (30), and (31) were synthesized, and a moisture absorption test was conducted in the same manner as in Example 1 to calculate the molar moisture absorption capacity, molar moisture absorption rate, gram moisture absorption rate, and gram moisture absorption rate. The results are shown in Table 3.

[0056]

Table 3

[0057] As shown in Table 4 above, the above specific salts (23), specific salts (24), specific salts (26), specific salts (27), specific salts (28), specific salts (29), specific salts (30), and specific salts (31) also showed high moisture absorption performance. In particular, compared with the cholinium dimethyl phosphate ([Ch][DMPO4]) described in Non-Patent Document 8 shown in Comparative Example 5, the above specific salts (23), specific salts (24), specific salts (26), specific salts (28), specific salts (29), specific salts (30), and specific salts (31) showed high molar moisture absorption capacity, and the specific salt (27) showed molar moisture absorption rate. Furthermore, it showed excellent moisture absorption capacity compared with silica gel for drying (Comparative Example 2), calcium chloride for drying (Comparative Example 1), and cholinium dimethyl phosphate ([Ch][DMPO4]) of Non-Patent Document 8 (Comparative Example 5).

[0058] <Example 5 Metal Solubility Test> Metal pieces (10 mm in length × 15 mm in width × 2 mm in thickness) made of the following four types of metal materials, which are metals commonly used in air conditioners, were prepared. Fe-Zn: Galvanized zinc-aluminum-magnesium alloy plated steel sheet (trade name: SPHC steel sheet) Al: Corrosion-resistant aluminum A5052 Cu: Tough pitch copper C1100P SUS: Stainless steel SUS304

[0059] Metal pieces were placed in a sample tube containing 3 mL of an 80% by mass aqueous solution of the salt (19) of Example 1 and held at 80°C for 30 days. Then, the metal pieces were washed with deionized water and dried under reduced pressure. The mass of the metal pieces before and after the above treatment was measured with an electronic balance, and the mass change of the metal pieces before and after the above treatment was determined. The results are shown in Table 4.

[0060] A similar metal solubility test was carried out on an 80% by mass aqueous solution of the salt (25) of Example 2. The results are shown in Table 4. As a comparative test, a similar metal solubility test was carried out on a 30% by mass aqueous solution of lithium chloride of Comparative Example 4 and an 80% by mass aqueous solution of [Ch][DMPO4] of Comparative Example 5. The results are shown in Table 4.

[0061]

Table 4

[0062] When the specific salt (19) was used, corrosion did not occur in Fe-Zn, Al, and SUS. Therefore, it was found that the specific salt (19) has less corrosiveness than an aqueous lithium chloride solution.

[0063] When the specific salt (25) was used, as shown in Table 4, the mass change of various metal pieces was small compared with Comparative Example 3 using a 30% by mass aqueous solution of lithium chloride, and it was found that the metal corrosiveness was low. In particular, for the three metals of Fe-Zn, Al, and SUS, the dissolution of the metal was almost zero.

[0064] <Odor test> 1.0 mL of an 80% by mass aqueous solution of each of the above specific salts (19) and (25) was placed in a sealed container and kept at 80 °C for 10 days. Then, three panelists evaluated the odor when the sealed container was opened based on their own sense of smell. As a result, in both cases where the specific salt (19) and the specific salt (25) were used, all three panelists evaluated that there was no odor.

[0065] <Viscosity test> 80% by mass aqueous solutions of the above specific salt (19) and specific salt (25) were prepared, and the viscosities of the prepared aqueous solutions in the range from 25 °C to 60 °C were measured using a cone-plate viscometer (DV2TCP manufactured by Eihong Seiki Co., Ltd.). The results are shown in the graphs of FIGS. 4(a) and (b). As shown in the graphs of FIGS. 4(a) and (b), the 80% by mass aqueous solutions of the specific salt (19) and the specific salt (25) showed lower viscosities than the 80% by mass aqueous solution of [Ch][DMPO4] described in Non-Patent Document 8 of Comparative Example 5. Specifically, at any temperature, the specific salt (19) had a viscosity more than 4 times lower than that of [Ch][DMPO4].

Industrial Applicability

[0066] The moisture absorbent of the present invention can be used in devices such as air conditioners and absorption refrigerators. In particular, since the generation of odors is suppressed, it is particularly suitable for open-system applications such as desiccant air conditioners. The moisture absorbent of the present invention can achieve high moisture absorbency. The moisture absorbent of the present invention can be made less corrosive to various metals such as zinc, copper, aluminum, and stainless steel. Further, the moisture absorbent of the present invention can be made low in toxicity to living bodies. Furthermore, the moisture absorbent of the present invention can suppress the generation of odors.

Claims

1. A moisture absorbent comprising a salt composed of an ammonium cation and a phosphate ester anion, wherein the salt is at least one selected from the group consisting of salts represented by formulas (23) to (31). 【Chemical 1】

2. An apparatus comprising the moisture absorbent according to Claim 1.

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