JP2006008535A - Magnesium-sodium acetate double salt and antifreezing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new compound or composition as an antifreezing agent, and to provide a suitable method for producing the same. <P>SOLUTION: The new compound is a magnesium-sodium acetate double salt of the formula:Mg<SB>2</SB>Na(CH<SB>3</SB>COO)<SB>5</SB>. The method for producing the antifreezing agent comprising as active ingredient the double salt or its mixture with sodium acetate or magnesium acetate comprises the following steps:(A) An aqueous acetic acid solution is incorporated with sodium hydroxide in an amount equivalent to 0.17-0.62 equivalent of the acetic acid therein to prepare an aqueous acetic acid solution containing sodium acetate, (B) the resultant aqueous solution is incorporated with magnesium oxide in an amount equivalent to the remaining acetic acid to carry out a reaction under agitation, and (C) antifreezing agent particles are granulated from a pasty material containing the resultant reaction product. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Field of use

The present invention relates to a novel magnesium / sodium double salt and a process for producing the same. The present invention also provides a cryoprotectant using a mixture of sodium acetate and magnesium acetate in a specific ratio, the above double salt, or a mixture of this double salt and sodium acetate or magnesium acetate as an active ingredient, and a method for producing the same. Also related.

In this specification, the term “antifreeze agent” refers to an agent used to melt and flow away snow and ice piled up on roads and bridges in cold regions, or to prevent snow and ice from freezing. means.

Conventionally, sodium chloride and calcium chloride have been used to prevent freezing of roads and the like, but salt damage has become a problem. Instead, calcium acetate / magnesium (abbreviated as “CMA”) is used. Came to be used. CMA has the advantage that it does not cause salt damage because it does not have the antifreezing effect on chloride but biochemically decomposes in the environment. It is known that CMA has a double salt in which 3 mol of CA (calcium acetate) and 7 mol of MA (magnesium acetate) are bonded.

On the other hand, potassium acetate (hereinafter abbreviated as “PA”) is also used as an antifreezing agent. Since the heat of fusion per unit weight is higher for alkali metal acetates than for alkaline earth metal acetates, PA can be said to be a higher performance antifreeze, but it can be justified because of its higher price, Used only in airports and other limited areas. Therefore, it has been proposed to use CMA and PA together (Patent Document 1). The composition of a typical CMA + PA (hereinafter abbreviated as “CMAK” in accordance with the description of the above-mentioned US patent) consists of 75% by weight of CMA of C / M = 3/7 and 25% by weight of PA.

The applicant, together with co-developers, researched to produce anti-freezing agents using dolomite that is relatively abundantly produced in the country, and as a result, CA, MA and PA form ternary double salts. It was discovered that the ternary double salt was useful as a cryoprotectant combining the advantages of both CMA and PA, and has already been disclosed (Patent Document 2).

Urea (abbreviated as “U”) is also known to be useful as a cryoprotectant. The applicant has found that a system in which urea (abbreviated as “U”) is added to at least one of the acetate group consisting of CA, MA, CMA and CMPA has a synergistic effect as an antifreeze agent, It has already been disclosed (Patent Document 3). This cryoprotectant has a lower electrical conductivity than an acetate-only cryoprotectant, so if the aqueous solution enters after thawing, it may affect the electrical system and cause troubles, such as railway and airport facilities. This is advantageous in that the cost is low.
US Pat. No. 5,214,483 Patent No. 2790082 Japanese Patent No. 3097629

Further, the applicant continued research on anti-freezing agents, and in a system containing a P component, as a raw material, P could be replaced with cheaper sodium (abbreviated as “S”), and it would be possible to obtain it relatively inexpensively. The combination with the obtained M component was examined. As a result, a mixture of sodium acetate (abbreviated as “SA”) and MA within a certain range is useful as an anti-freezing agent, and further, a double salt of SA and MA in a molar ratio of 2: 1, ie Mg _{It has been found that 2} Na (CH ₃ COO) ₅ is formed, that this material is a novel compound, and that it exhibits high performance as a cryoprotectant.

As is apparent from the above, the object of the present invention is to provide a novel sodium acetate / magnesium double salt and a method for producing the same, as well as a novel compound or composition as a cryoprotectant, and suitable production thereof. It is to provide a method.

The magnesium acetate / sodium double salt of the present invention is represented by the following formula.
Mg ₂ Na (CH ₃ COO) ₅
Hereinafter, this is abbreviated as “MSA”. This substance is a novel compound not described in the literature, and shows a unique X-ray diffraction chart. Its physical properties are as follows.
Molecular weight (mass number): 366.82
Melting point: 280.4 ° C
Density: 1.50 g / cm ³
Crystal water: None

The method of the present invention for producing this double salt MSA comprises the following steps.
(A) adding a hydroxide, carbonate or bicarbonate of sodium hydroxide in an amount corresponding to 1/5 equivalent of acetic acid therein to an aqueous acetic acid solution to form an aqueous acetic acid solution containing sodium acetate;
(B) A magnesium oxide, hydroxide or carbonate in an amount corresponding to 4/5 equivalents of the original acetic acid is added to the aqueous solution from step a, and a 1: 2 mixed solution of sodium acetate and magnesium acetate. And (c) obtaining Mg ₂ Na (CH ₃ COO) ₅ from the mixed aqueous solution obtained in step b.

The antifreezing agent of the present invention comprises an SA-MA mixture containing SA, that is, CH ₃ COONa and MA, that is, Mg (CH ₃ COO) ₂ , in a molar ratio of 1: 0.62 to 5.0. The salt MSA or a mixture of this double salt and SA or MA is used as an active ingredient.

The method of the present invention for producing the antifreeze particles comprises the following steps.
(A) adding an amount of sodium hydroxide corresponding to 0.17 to 0.62 equivalent of acetic acid to an aqueous acetic acid solution to form an aqueous acetic acid solution containing sodium acetate;
(B) Addition of an equivalent amount of magnesium oxide to the aqueous solution from Step A and react with stirring, and (C) Freezing prevention from the paste-like material containing the reaction mixture of Step B Step of granulating agent particles.

According to the present invention, a novel compound Mg ₂ Na (CH ₃ COO) ₅ which is an MSA double salt is provided. This double salt is useful as an antifreezing agent and can be used as it is without requiring a step of blending two components.

In addition to this double salt, the present invention also provides a specific proportion of SA-MA mixture, a novel double salt MSA, and a cryoprotectant which is a mixture of this double salt and SA or MA. These cryoprotectants are more effective than known CMPA.

The antifreezing agent of the present invention can be produced in a conventional reaction apparatus, and can be provided in either spherical or angular shape depending on the application. In recent years, relatively inexpensive natural magnesium oxide has become available as a magnesium source, and sodium compounds are less expensive than potassium compounds, so that the antifreeze of the present invention can be produced at low cost. .

As described above, SA and MA constituting the cryoprotectant can obtain a synergistic effect of two components by selecting a molar ratio of SA and MA within the range of 1: 0.62 to 5.0. . What formed a double salt at a molar ratio of just 1: 2 is the SMA double salt of the present invention, which is more effective as a cryoprotectant than a simple mixture having the same molar ratio. This is because the energy level is lower than the average of each single salt due to the formation of the double salt, and the heat of fusion is increased.

As can be understood from the above description, the antifreezing agent of the present invention may have the following five modes.
1) SA + MA (mixture of simple salts)
2) SMA (double salt)
3) SMA + SA (mixture of double salt and single salt)
4) SMA + MA (mixture of either double salt or single salt)
5) SMA + SA + MA (mixture of both double salt and single salt)
In any case, it is necessary that the above-described conditions regarding the molar ratio are satisfied for the entire mixture. If it is the same molar ratio, what contains as many double salts as possible is preferable.

Various apparatuses and methods can be used for the manufacture of the cryoprotectant. In the granulation in the above step C, it is convenient to carry out the step B using a reaction mixer, and the resulting paste-like product is made into particles by a rotary granulator, but from the extruder as a strand It can also be extruded and cut into pellets. Alternatively, the above paste can be flowed down on a heating drum having a heat medium through it and dried, scraped to obtain a powder, and the powder can be compressed with a roll to be briquetted. In order to spread with a conventional spreader, particles having a size of 2 to 5 mm and an average of about 4 mm and having a large specific gravity are suitable.

A mixed aqueous solution of acetic acid and sodium acetate was prepared by adding 266 g of a 48% sodium hydroxide aqueous solution (0.2 equivalents to acetic acid) to 970 g of a 99% acetic acid aqueous solution and stirring to neutralize. did. To this mixed aqueous solution, 258 g of magnesium oxide (equivalent to the remaining acetic acid) was added with stirring. The reaction product solution was heated to evaporate to dryness, and the solid obtained by heating to 200 ° C. was subjected to X-ray diffraction.

FIG. 1 shows a diffraction chart of the substance that is considered to be MSA (referred to as “prototype 1”). For comparison, a diffraction chart of SA used as a raw material is shown in FIG. 2, a diffraction chart of MA of a reagent is shown in FIG. 3, and a diffraction chart of a 1: 2 mixture of SA and MA is shown in FIG. . The chart of FIG. 1 has a different peak from the chart of FIG. 4 and clearly shows that different kinds of substances are generated. The peak in FIG. 1 does not correspond to that of a known substance, indicating that this substance is a novel compound.

According to the following test method, the ice melting ability of the prototype 1 obtained above was measured.
(Measuring method of ice melting capacity)
60 g of water was put into a petri dish having a diameter of 9 cm and a depth of 2 cm, cooled to -5 ° C or -10 ° C and frozen, then 5 g of the sample was sprayed on ice and left in an atmosphere at -5 ° C. The amount of ice melt is measured after 30 minutes, 60 minutes, 1 hour 30 minutes, 2 hours, 3 hours and 4 hours.

The results of the ice melting test are shown in the graph of FIG. 5 in comparison with the measurement results of the conventional cryoprotectant CMA and the known one, CMPA (Patent Document 2), which were tested under the same conditions for comparison. From the data in FIG. 5, it can be seen that the antifreezing effect per unit weight exhibited by the salt concentrate of the present invention is higher than the conventional one.

The ice melting ability of prototype 1, that is, the present salt Mg ₂ Na (CHOO) ₅ of the present invention, is the melting ability of an equimolar mixture of CH ₃ COONa and Mg (CH ₃ COO) ₂ constituting the single salt. Compared with. The results are as shown in the graph of FIG. 6. From this data, it can be seen that the antifreezing effect per unit weight exhibited by the double salt of the present invention is higher than that of the mixture of the constituent single salts.

In Example 1, an aqueous sodium hydroxide solution was added so that the amount of sodium hydroxide relative to acetic acid in the aqueous acetic acid solution was 0.333 equivalent or 0.5 equivalent, and the mixture was stirred and neutralized to obtain acetic acid and sodium acetate. A mixed aqueous solution was prepared. Thereto was added magnesium hydroxide in an amount to neutralize the remaining acetic acid and added with stirring. The reaction product solution was heated to evaporate to dryness, and the following two salt mixtures were prepared.
“Prototype 2” SA: MA = 1: 1 (mixture of SMA and SA)
“Prototype 3” SA: MA = 2: 1 (mixture of SMA and MA)

The ice melting capacity of the prototype 1 and the prototypes 2 and 3 was measured. As a result, it was found that prototypes 1 and 2 have almost the same melting ability as prototype 3, which is slightly higher.

An amount corresponding to 0.17, 0.33, 0.50, 0.58, or 0.62 equivalent to acetic acid in 970 g of acetic acid aqueous solution having the same concentration of 99% as used in Example 1 5 types of aqueous acetic acid solutions containing SA were prepared. To these acetic acid aqueous solutions, magnesium hydroxide corresponding to the equivalent amount of acetic acid remaining therein was added with stirring.

The resulting solution of the reaction mixture is allowed to flow down on a roll that can be heated on the surface through a heating medium, scraped and solidified after being dried, and sieved to collect a size of 2 to 5 mm. A powdery antifreeze was obtained. The ratio (mol%) of SA, MA and MSA in the obtained antifreeze powder is as shown in Table 1 below. The result of X-ray diffraction analysis of sample No. 4 was substantially the same as the chart shown in FIG. 1 except that the presence of some small peaks due to impurities in the raw material was observed.

The ice melting ability of these antifreeze agents was measured, and the graph of FIG. 7 was obtained. For example, the relationship between the melting ability of ice after 3 hours and the value of SA: MA in the cryoprotectant in this graph is as follows.
MA: SA ratio 5.0 3.0 2.0 1.0 0.71 0.62 0.50
Amount of ice melt (g) 29.7 31.7 33.9 34.8 34.9 36.0 24.6
From this result, it can be seen that the above-mentioned MA: Mg molar ratio should be selected within the range of 1: 0.62 to 5.0 in order to clearly obtain the synergistic effect as the antifreezing agent.

The X-ray-diffraction chart of the magnesium acetate sodium double salt (MSA) which is a novel compound of this invention. X-ray diffraction chart of magnesium acetate (MA). X-ray diffraction chart of sodium acetate (SA). X-ray diffraction chart of a 2: 1 mixture of magnesium acetate (MA) and sodium acetate (SA). The graph which shows the time change of the amount of ice melting produced in -5 degreeC, using the double salt MSA of the present invention as an antifreezing agent, and comparing the ice melting ability with a known antifreezing agent. The graph which shows the time change of the amount of ice melting which occurred in -5 degreeC, and is the data which compared the ice-melting ability of the cryoprotectant which consists of double salt MSA of this invention with that of a (MA + SA) single salt mixture. It is the data which compared those ice-melting abilities about some examples of the antifreezing agent of this invention, and is a graph which shows the time change of the amount of ice-melting produced at -5 degreeC.

Claims (5)

A double salt represented by the formula Mg ₂ Na (CH ₃ COO) ₅ . A method for producing the double salt according to claim 1, comprising the following steps.
(A) adding an amount of sodium hydroxide corresponding to 1/5 equivalent of acetic acid therein to an aqueous acetic acid solution to form an aqueous acetic acid solution containing sodium acetate;
(B) Add magnesium oxide or hydroxide in an amount corresponding to 4/5 equivalents of the original acetic acid to the aqueous solution from step a to make a 1: 2 mixed solution of sodium acetate and magnesium acetate. And (c) obtaining Mg ₂ Na (CH ₃ COO) ₅ from the mixed aqueous solution obtained in step b. An acetate mixture containing CH ₃ COONa and Mg (CH ₃ COO) ₂ in a molar ratio of 1: 0.62 to 5.0, a double salt represented by Mg ₂ Na (CH ₃ COO) ₅ , or An antifreezing agent comprising a mixture of the double salt and sodium acetate or magnesium acetate as an active ingredient. Antifreezing agent particles obtained by granulating the antifreezing agent according to claim 3 into particles suitable for mechanical spraying. A method for producing the antifreezing agent particles according to claim 4, comprising the following steps.
(A) a step of adding an amount of sodium hydroxide corresponding to 0.17 to 0.62 equivalent of acetic acid to an aqueous acetic acid solution to form an aqueous acetic acid solution containing sodium acetate;
(B) A step of adding an equivalent amount of magnesium oxide to the initial remaining acetic acid to the aqueous solution from step A and stirring to react, and (C) a paste-like material containing the reaction mixture of step B. Step of granulating agent particles.

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