JPH11349936A - Heat regenerating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat regenerating material without reducing a relative amount of aqueous solution in a jelly material having excellent heat regenerating ability and capable of making a jelly material even being an aqueous solution of a salt of more than bifunctional metallic ion by mainly comprising a jelly material containing an aqueous solution of a compound formable an eutectic crystal and a specific water-absorbing resin. SOLUTION: This heat regenerating material is mainly composed of (A) an aqueous solution of a compound formable an eutectic crystal and (B) a jelly material containing a polymer (preferably polyvinyl acetamide) having a repeating unit of the formula (R<1> is a 1-6C acyl) as a water-absorbing resin. As the component A, salts of a monofunctional anion such as sodium chloride is preferable. Preferably, a concentration of an aqueous solution of the component A is equal or the vicinity of the concentration of the component A in the eutectic crystal. In a case of an aqueous solution of sodium chloride having 23.3 wt.% of concentration in the eutectic crystal, a concentration of the aqueous solution is preferably 20-25 wt.%. Preferably, 1-5 pts.wt. of the component B is used to 100 pts.wt. of an aqueous solution of the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerator material, and more particularly, to a regenerator material mainly composed of a gel made of an aqueous solution of a compound capable of forming a common crystal such as sodium chloride and a water-absorbing resin.

[0002]

BACKGROUND OF THE INVENTION Certain inorganic salts, such as sodium chloride, can form eutectics that are eutectic with water, which eutectics generally have a low eutectic point. For example, the eutectic point of the sodium chloride co-crystal is −21.1 ° C. Conventionally, an aqueous solution of a compound capable of forming a quarts using the latent heat at the time of melting of the quarts has been used as a cold storage material.

However, the use of the above-mentioned aqueous solution itself as a cold storage material has a problem that when the container for storing the aqueous solution is damaged, the aqueous solution flows out and contaminates the surroundings. In addition, during the repetition of solidification and melting, the inorganic salt partially precipitates and precipitates at the bottom of the storage container, and the concentration of the inorganic salt is different between the upper and lower portions of the aqueous solution, so that it is difficult to control the cooling temperature. There is also a problem that. In order to avoid such a problem, a water-absorbing resin is added to this aqueous solution, and the water-absorbing resin absorbs the inorganic salt aqueous solution to form a gel, which is used as a cold storage material.

[0004] It is considered that the above-mentioned gel-like substance is because the water-absorbent resin forms a large number of stitches and an inorganic salt aqueous solution is confined in each individual mesh. Since the gel material has poor fluidity, even if the storage container is damaged, the gel material does not flow out, and there is no problem of contaminating the surroundings. Also, in the gel-like material, even if the inorganic salt precipitates in each network, the precipitated inorganic salt remains in each network and does not precipitate at the bottom of the storage container. There is no problem that the concentration difference of the inorganic salt between the upper part and the lower part occurs.

As such a water-absorbing resin, an acrylate-based water-absorbing resin, a graft starch-based water-absorbing resin, and the like having a high water absorbing performance have been proposed. However, these water-absorbing resins have a high water-absorbing ability with respect to pure water, but have an extremely poor absorption capacity with respect to an aqueous electrolyte solution such as a sodium chloride solution. As a result, there is a problem that the relative amount of the aqueous solution in the gel-like material is reduced and the cold storage ability is reduced. In addition, when the inorganic salt is a salt of a divalent or higher metal ion, there is a problem that the water-absorbing resin forms a chelate with the metal ion and hardly absorbs the aqueous solution.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to reduce the relative amount of an aqueous solution in a gel-like material, to provide a good cold storage capacity, and to obtain a divalent solution. It is an object of the present invention to provide a regenerative material that can be a gel even in the case of an aqueous solution of the metal ion salt.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present inventor has a good absorption capacity especially for an aqueous electrolyte solution.
As a result of intensive studies on a water-absorbing resin that does not reduce the relative amount of the aqueous solution in the gel, the present invention has been completed. That is, the present invention is as follows.

An aqueous solution of a compound capable of forming a quarts,
The repeating unit represented by the general formula (1) as a water absorbent resin

[0009]

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[0010] A regenerator material comprising, as a main component, a gel-like material comprising a polymer having (wherein R ¹ represents an acyl group having 1 to 6 carbon atoms). The cold storage material according to the above, wherein the water-absorbing resin is poly N-vinylacetamide. The regenerative material according to the above or the above, wherein the compound capable of forming a common crystal is an inorganic salt or an organic salt. The regenerator according to the above, wherein the inorganic salt or the organic salt is a salt of at least one cation selected from the group consisting of an alkali metal ion, an alkaline earth metal ion and an ammonium ion. The cold storage material as described above, wherein the inorganic salt or the organic salt is a monovalent anion salt. When the inorganic salt or the organic salt is NaCl, CaCl ₂ , NH
_4. The cold storage material according to any one of the above items, which is at least one selected from the group consisting of ₄ Cl, MgCl ₂ and KNO ₃ .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The regenerative material of the present invention is mainly composed of a gel-like substance containing an aqueous solution of a compound capable of forming a eutectic crystal and a water-absorbing resin. The water-absorbing resin used in the present invention has a general formula (1)

[0012]

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(Wherein, R ¹ represents an acyl group having 1 to 6 carbon atoms). When such a polymer is used as the water-absorbing resin, not only pure water, but also an aqueous solution of a compound capable of forming a quarts crystal described later, particularly an aqueous solution of an electrolyte, has a good absorption capacity, and absorbs the aqueous solution. To form a gel.

[0014] In formula (1), R ¹ has 1 to 6 carbon atoms.
Examples of the acyl group include formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl,
Examples thereof include an isovaleryl group and a hexanoyl group, and among these, an acetyl group is preferable because of its excellent absorption ability. Specific examples of such a suitable polymer include poly N-vinylacetamide (hereinafter, also referred to as PNVA).

The water-absorbing resin used in the present invention may be one in which the vinyl group is polymerized linearly, or one in which this is cross-linked. Examples of the polymerization method include radical polymerization, aqueous solution polymerization, precipitation polymerization, emulsion polymerization, and reverse phase suspension polymerization.

The water-absorbing resin used in the present invention may be a commercially available product such as G of water-absorbing resin PVNA manufactured by Showa Denko KK.
E grade (water-soluble linear polymer); GX grade (highly three-dimensional crosslinked product of PNVA); NA-010, NA
-150, NA-500, etc.
NVA (lightly three-dimensional crosslinked product) and the like.

The number of the repeating units represented by the general formula (1) (degree of polymerization) is not particularly limited, as long as it can absorb an aqueous solution of a compound capable of forming a common crystal described below to form a gel. Has an average molecular weight of 1 × 10 ⁶ to 1 × 10 ⁷
It is about.

The above water-absorbing resins may be used alone or in combination of two or more. In addition, as long as it can absorb an aqueous solution of a compound capable of forming a co-crystal described later and become a gel, it may be used in combination with a conventionally known water-absorbing resin.

The amount of the water-absorbing resin used varies depending on the type thereof and the type of a compound capable of forming a quartz as described later.
Generally, the amount is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the aqueous solution of the compound. From the viewpoint of the cold storage capacity of the cold storage material of the present invention, the necessary gel is used. It is preferable that the amount is the minimum amount that can be a solid.

The compound capable of forming a eutectic crystal used in the present invention is a compound capable of forming a eutectic with water and is chemically non-reactive with the above-mentioned water-absorbing resin. It can be absorbed by the polymer water-absorbent resin represented by the repeating unit of the formula (1) to form a gel.

It is preferable that the compound capable of forming a co-crystal has good solubility in water.
The solubility in water is preferably 1% by weight or more, particularly preferably 4% by weight or more. The solubility in water is 25
% By weight of solute contained in 100 g of saturated aqueous solution at 100C.

Examples of the compound capable of forming such a co-crystal include various inorganic salts and organic salts. For example, at least one compound selected from the group consisting of alkali metal ions, alkaline earth metal ions and ammonium ions Salts of the cations, specifically, potassium salts such as potassium chloride, potassium fluoride, potassium iodide, potassium hydrogen fluoride, potassium nitrate, potassium nitrite, potassium carbonate, potassium hydrogen carbonate, tripotassium phosphate, potassium hydroxide; Sodium salts such as sodium chloride, sodium fluoride, sodium bromide, sodium iodide, sodium carbonate, sodium nitrate, sodium silicate, disodium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium hydroxide, sodium formate, sodium acetate, etc. Ammonium chloride, fluorine Ammonium, ammonium bicarbonate, ammonium sulfate, ammonium dihydrogen phosphate, ammonium salts such as phosphate diammonium hydrogen; Other,
Examples include magnesium chloride, calcium chloride, zinc chloride, barium chloride, magnesium sulfate, zinc sulfate, calcium nitrate, magnesium nitrate, and aluminum nitrate.

As described above, the conventionally proposed water-absorbing resin forms a chelate with a divalent or higher polyvalent metal ion, so that its practical use is difficult. However, the water-absorbing resin used in the present invention is There is no such problem, and an aqueous solution of a salt of a divalent or higher polyvalent metal ion can be used.

Among the above-mentioned salts, the salts of monovalent anions are absorbed by a smaller amount of water-absorbing resin, and the aqueous solution thereof is gelled, as compared with salts of divalent or higher polyvalent anions. It is easy to become a shape. Preferred monovalent anion salts include potassium chloride, potassium fluoride, potassium iodide, potassium hydrogen fluoride, potassium nitrate, potassium nitrite, potassium hydroxide, sodium chloride, sodium fluoride, sodium bromide, and sodium iodide. , Sodium nitrate, sodium hydroxide, sodium formate, sodium acetate, ammonium chloride, ammonium fluoride, magnesium chloride, calcium nitrate, magnesium nitrate, aluminum nitrate and the like.

In addition to the salts described above, there are other compounds that can be used as compounds capable of forming eutectic crystals. For example, organic compounds such as glycine and urea can form eutectic crystals having a low eutectic point.

In the present invention, the compound capable of forming a common crystal may be used alone or in combination of two or more if a compound can be formed.

Examples of the eutectic crystal having a low eutectic point are shown below. % By weight is the compound concentration in the co-crystal. Sodium chloride (23.3% by weight, eutectic point: -21.1 ° C); calcium chloride (30.2% by weight, eutectic point: -49.8)
C), potassium nitrate (9.7% by weight, eutectic point: -2.8)
C); ammonium chloride (19.5% by weight, eutectic point:-
16.0 ° C.); magnesium chloride (20.6% by weight, eutectic point: −33.6 ° C.) and the like.

The concentration of the aqueous solution of the compound capable of forming the common crystal is not particularly limited as long as it can form the common crystal, but is preferably equal to or close to the concentration of the compound in the common crystal as described above. . For example, in the case of an aqueous sodium chloride solution having a compound concentration of 23.3% by weight in the quartz crystal, the concentration is about 15 to 28% by weight, particularly about 20 to 25% by weight.

The regenerator material of the present invention may be used alone or, if necessary, may be mixed with a supercooling inhibitor such as carbon black, graphite, metaacetaldehyde or a known additive for regenerator materials. May be used.

[0030]

The polymer water-absorbing resin having a repeating unit represented by the general formula (1) forms a quarts crystal as compared with a conventional acrylate-based water-absorbing resin or a graft starch-based water-absorbing resin. Even if it is an aqueous solution of the compound to be obtained, especially an aqueous solution of an electrolyte, since it has a good absorption capacity, it can be used as a small amount to absorb an aqueous solution of the compound capable of forming a quarts and become a non-flowable gel. . Further, since the amount of the water-absorbing resin used is small, the relative amount of the aqueous solution in the gel-like material does not decrease, and therefore, the cooling ability of the gel-like material does not decrease. In addition, due to the good absorption capacity of the above water absorbent resin,
It is difficult for the water-absorbent resin and the aqueous solution in the gel to separate into phases. Furthermore, since the above-mentioned water-absorbing resin does not form a chelate with a divalent or higher polyvalent metal ion, a gel-like substance can be obtained even when an aqueous solution of such a salt is used.

[0031]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1 to 5 PNVA (trade name "NA-150" manufactured by Showa Denko KK) was prepared as a water absorbing resin. On the other hand, aqueous solutions of various compounds shown in Table 1 were prepared, and 100 g of the aqueous solutions were prepared.
3 g of a water-absorbent resin was added and mixed well to obtain a gel-like cold storage material.

Comparative Examples 1 to 5 Examples 1 to 5 were used except that a polyacrylate resin (trade name "ST-500" manufactured by Sanyo Chemical Industries Co., Ltd.) was used as the water absorbing resin. In the same manner as in Example 5, a gel-like cold storage material was obtained.

Comparative Examples 6 to 10 Examples 1 to 10 were repeated except that a graft polymerization type starch resin (trade name "ST-100" manufactured by Sanyo Chemical Industries, Ltd.) was used as the water-absorbing resin. In the same manner as in Example 5, a gel-like cold storage material was obtained.

The following flow tests were performed on each of the cold storage materials of Examples 1 to 5 and Comparative Examples 1 to 10. Table 1 shows the results.
Shown in

<Flow Test> Each gel of Examples 1 to 5 and Comparative Examples 1 to 10 was placed in a 50 ml beaker.
g, then invert the beaker. In that case, the determination is made based on whether or not the gel has fallen from the beaker.

[0037]

[Table 1]

[0038]

The regenerator material of the present invention has the following effects. (1) Since it is a non-flowable gel-like material, there is no problem of spillage and contaminating the surrounding environment due to breakage of the container for storing the gel-like material. (2) The water-absorbing resin used in the present invention is an aqueous solution of a compound capable of forming a quartz crystal, particularly an aqueous solution of an electrolyte, as compared with a conventional acrylate-based water-absorbing resin or a graft starch-based water-absorbing resin. Even so, since it has good absorption capacity, it can absorb an aqueous solution of a compound capable of forming a quarts and use it in a small amount to form a non-flowable gel which is difficult to phase separate. Then, the relative amount of the aqueous solution in the gel-like material does not decrease, and therefore, the cooling power of the gel-like material does not decrease. (3) The acrylate-based water-absorbent resin and the graft starch-based water-absorbent resin form a chelate with a divalent or higher polyvalent metal ion, whereas the water-absorbent resin used in the present invention has a problem. There is no. Thus, the cold storage material of the present invention can be a cold storage material using an aqueous solution of a salt of a divalent or higher polyvalent metal ion.

Claims (6)

[Claims] 1. An aqueous solution of a compound capable of forming a common crystal,
A repeating unit represented by the general formula (1) as a water absorbent resin (Wherein R ¹ represents an acyl group having 1 to 6 carbon atoms). 2. The cold storage material according to claim 1, wherein the water-absorbent resin is poly N-vinylacetamide. 3. The regenerative material according to claim 1, wherein the compound capable of forming a common crystal is an inorganic salt or an organic salt. 4. The cold storage material according to claim 3, wherein the inorganic salt or the organic salt is a salt of at least one cation selected from the group consisting of an alkali metal ion, an alkaline earth metal ion and an ammonium ion. 5. The cold storage material according to claim 3, wherein the inorganic salt or the organic salt is a monovalent anion salt. 6. An inorganic or organic salt comprising NaCl, Ca
Cl _2, NH ₄ Cl, the cold accumulating material according to claim 3 is at least one selected from the group consisting of MgCl ₂ and KNO _3.