Method for producing calcium hydroxide solution

Abstract

To mass-produce calcium hydroxide aqueous solution at low cost and with stable efficiency through a process that allows the reaction to proceed solely through pure chemical reactions. [Solution] A method for producing an aqueous calcium hydroxide solution, comprising: a first step S1 in which a calcium salt and sugars are dissolved in water to obtain an aqueous calcium ion solution as a first aqueous solution L1; a second step S2 in which an alkali metal hydroxide in a mass ratio of 25% to 100% or less of the calcium salt dissolved in water in the first step S1 is dissolved in water to obtain an aqueous hydroxide ion solution as a second aqueous solution L2; and a third step S3 in which the first aqueous solution L1 and the second aqueous solution L2 are mixed to obtain an aqueous calcium hydroxide solution.

Description

Technical Field

[0001] The present invention relates to a method for producing an aqueous calcium hydroxide solution.

Background Art

[0002] An aqueous calcium hydroxide solution, which is a kind of reducing solution, is known to be useful for inhibiting the growth and inactivating microorganisms, and the demand for various antibacterial agents or their raw materials has been increasing year by year.

[0003] Conventionally, as a production method for producing a reducing solution such as an aqueous calcium hydroxide solution, a production method (see Patent Document 1) that passes through a step of generating hydroxide ions (OH - ) by electrolysis has been widely used.

[0004] In addition, as other production methods for reducing solutions, a production method (see Patent Document 2) that passes through a step of dissolving hydrogen gas in raw water using a pressurizing device, or a production method (Patent Document 3) that passes through a step of eluting calcium etc. from natural materials such as shells using a contact solid material such as activated carbon or medicinal stones is also carried out. [[ID=?]]

[0005] Here, in the production method disclosed in Patent Document 1, the electrolysis treatment is an essential step. Therefore, in order to implement this production method, it is essential to install a large-scale electrolysis treatment device. Also, in order to implement the production method disclosed in Patent Document 2, it is essential to install a hydrogen pressurizing device and other auxiliary equipment. That is, in any of the above production methods, the initial investment in production equipment and the burden of operating costs tend to be an excessive burden.

[0006] On the other hand, in order to implement the production method disclosed in Patent Document 3, it is necessary to secure a large amount of activated carbon, medicinal stones, and shells, which are natural raw materials. Also, the shell as a raw material has low solubility, and a filtration process that is a large burden of time and labor is inevitable, which is also economically disadvantageous. Therefore, it has been difficult to stably mass-produce a reducing solution by this production method. There seems to be a formatting issue with the "?". It should be an ID number, but it's not clear if it's a typo. If it's a real ID number, it should be preserved as is in the translation. If it's a mistake, it should be corrected in the original text before translation. I've left it as is in the translation for now.

[0007] The present inventor has already developed a method for producing a reducing solution that can solve the problems of each of the manufacturing methods disclosed in the above-mentioned Patent Documents 1 to 3. Specifically, this manufacturing method is a method for producing a reducing solution by dissolving a mixture of calcium chloride dihydrate and sugars, etc., in water in a container, and can be carried out by a process that proceeds solely through a pure chemical reaction without requiring large-scale industrial equipment such as electrolytic treatment equipment or hydrogen pressurization equipment (see Patent Document 4).

[0008] However, in particular, when producing an aqueous calcium hydroxide solution, the low solubility of calcium hydroxide (Ca(OH)2) in water becomes the rate-limiting factor. Therefore, even if the production method disclosed in Patent Document 4, which assumes the dissolution of a raw material mixture in water in a single container, is directly applied to the production of calcium hydroxide, it remains difficult to stably mass-produce an aqueous calcium hydroxide solution. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 8-187492 [Patent Document 2] Japanese Patent Publication No. 2004-351399 [Patent Document 3] Japanese Patent Publication No. 2006-68640 [Patent Document 4] Patent No. 6455689 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention aims to provide a method for producing an aqueous calcium hydroxide solution that can be mass-produced stably and at low cost by a process that allows the aqueous calcium hydroxide solution to proceed solely through pure chemical reactions. [Means for solving the problem]

[0011] The inventors of the present invention have come to the realization that the above problem can be solved by significantly improving the method for producing a reducing solution disclosed in Patent Document 4, which they themselves developed, and by performing the steps of "dissolving a calcium salt in water" and "dissolving a hydroxide in water" separately and independently, and then mixing the two aqueous solutions obtained in each step. This led to the completion of the present invention. Specifically, the present invention provides the following.

[0012] (1) A method for producing an aqueous calcium hydroxide solution, comprising: a first step of dissolving a calcium salt and sugars in water to obtain an aqueous calcium ion solution as a first aqueous solution; a second step of dissolving an alkali metal hydroxide in water in a mass ratio of 25% to 100% or less of the calcium salt dissolved in water in the first step to obtain an aqueous hydroxide ion solution as a second aqueous solution; and a third step of mixing the first aqueous solution and the second aqueous solution to obtain an aqueous calcium hydroxide solution.

[0013] According to the method for producing an aqueous calcium hydroxide solution in (1), the aqueous calcium hydroxide solution can be produced in large quantities at low cost and stably through a process that allows the reaction to proceed solely through pure chemical reactions.

[0014] (2) The method for producing an aqueous calcium hydroxide solution according to (1), wherein sucrose is used as the sugar in the first step.

[0015] The method for producing an aqueous calcium hydroxide solution in (2) particularly promotes the dissolution of calcium ions during the first step in the production method in (1). Furthermore, it can prevent the browning of the first solution that occurs when monosaccharides such as glucose or galactose are used.

[0016] (3) The method for producing an aqueous calcium hydroxide solution according to (1) or (2), wherein in the first step, an amino acid is further dissolved in water to obtain the first aqueous solution.

[0017] The method for producing an aqueous calcium hydroxide solution according to (3) can significantly increase the antioxidant (reducing) properties of the aqueous calcium hydroxide solution obtained by the method according to (1) or (2).

[0018] (4) The method for producing an aqueous calcium hydroxide solution according to (3), wherein cysteine ​​is used as the amino acid in the first step.

[0019] The method for producing an aqueous calcium hydroxide solution in (4) can particularly enhance the antioxidant (reducing) properties of the aqueous calcium hydroxide solution obtained by the method in (3). This makes it possible to inactivate a wider range of bacteria and viruses, contributing to the stable supply of superior antibacterial agents at a lower cost. In addition, although cysteine ​​is sometimes included in antibacterial agents on its own, the action of calcium ions lowers the oxidation-reduction potential, resulting in improved antibacterial properties compared to when it is included alone.

[0020] (5) A method for producing an aqueous calcium hydroxide solution according to any one of (1) to (4), wherein in the first step, 4.5% by mass or more and 10.0% by mass or less of calcium chloride dihydrate is dissolved in water as the calcium salt, and 7% by mass or more and 10% by mass or less of sucrose is dissolved in water as the sugar to obtain the first aqueous solution, and in the second step, potassium hydroxide is used as the alkali metal hydroxide.

[0021] According to the method for producing an aqueous calcium hydroxide solution in (5), the effects described above, which are achieved by any of the methods from (1) to (4), can be reliably obtained with greater precision.

[0022] (6) A raw material combination set of an aqueous calcium hydroxide solution, comprising: a first aqueous solution which is an aqueous calcium ion solution containing a calcium salt and a saccharide; and a second aqueous solution which is an aqueous calcium hydroxide solution containing an alkali metal hydroxide in a mass ratio of 25% by mass or more and 100% by mass or less with respect to the calcium salt contained in the first aqueous solution. The raw material combination set of the two-liquid mixed type aqueous calcium hydroxide solution is composed of these.

[0023] According to the raw material combination set of the aqueous calcium hydroxide solution of (6), the aqueous calcium hydroxide solution can be stably mass-produced at low cost by a process that proceeds only by a pure chemical reaction. (7) The raw material combination set of the aqueous calcium hydroxide solution according to (6), wherein the saccharide contained in the first aqueous solution is sucrose.

[0024] According to the raw material combination set of the aqueous calcium hydroxide solution of (7), the dissolution of calcium ions in the first aqueous solution in the raw material combination set of the aqueous calcium hydroxide solution of (6) is particularly well promoted. Also, the browning of the first solution that occurs when using monosaccharides such as glucose and galactose can be prevented.

[0025] (8) The raw material combination set of the aqueous calcium hydroxide solution according to (6) or (7), wherein the first aqueous solution further contains an amino acid.

[0026] According to the raw material combination set of the aqueous calcium hydroxide solution of (8), the antioxidant property (reductivity) of the aqueous calcium hydroxide solution obtained by the raw material combination set of the aqueous calcium hydroxide solution of (6) or (7) can be significantly increased.

[0027] (9) The manufacturing method of the aqueous calcium hydroxide solution according to (8), wherein the amino acid contained in the first aqueous solution is cysteine.

[0028] The combination of raw materials for the calcium hydroxide aqueous solution in (9) can significantly increase the antioxidant (reducing) properties of the calcium hydroxide aqueous solution obtained using the combination of raw materials for the calcium hydroxide aqueous solution in (8). This allows for the inactivation of a wider range of bacteria and viruses, enabling the stable supply of superior antibacterial agents at a lower cost.

[0029] (10) A raw material combination set for a calcium hydroxide aqueous solution according to any one of (6) to (9), wherein the first aqueous solution contains, with respect to water, 4.5% by mass or more and 10.0% by mass of calcium chloride dihydrate as the calcium salt, and 7% by mass or more and 10% by mass of sucrose as the sugar, and the second aqueous solution contains potassium hydroxide as the alkali metal hydroxide.

[0030] According to the raw material combination set of calcium hydroxide aqueous solution (10), any of the raw material combination sets from (6) to (9) can reliably and with greater precision achieve the respective effects described above. [Effects of the Invention]

[0031] According to the present invention, a calcium hydroxide aqueous solution can be mass-produced stably and at low cost through a process that allows the reaction to proceed solely through pure chemical reactions. [Brief explanation of the drawing]

[0032] [Figure 1] This is a flowchart showing the procedure for producing the calcium hydroxide aqueous solution of the present invention. [Modes for carrying out the invention]

[0033] The best mode for carrying out the present invention will be described in detail below, with reference to drawings and other relevant documents as appropriate.

[0034] <Method for producing calcium hydroxide aqueous solution> The present invention provides a method for producing an aqueous calcium hydroxide solution, which is described in detail below, by a combination of steps that can be carried out solely by pure chemical reactions. In this specification, "carrying out solely by pure chemical reactions" specifically means carrying out the necessary chemical reactions without using processes that apply a large amount of energy from the outside, such as electrolysis apparatuses or pressurizing devices disclosed in Patent Documents 1 or 2.

[0035] [Overall structure] Figure 1 is a flowchart showing the procedure for the method of producing an aqueous calcium hydroxide solution according to the present invention. The method for producing an aqueous calcium hydroxide solution is a process consisting of three steps, from the first to the third. The first step S1 is a step of dissolving a calcium salt and sugars in water to obtain a first aqueous solution (calcium ion aqueous solution) L1. The second step S2 is a step of dissolving an alkali metal hydroxide in water in an amount that is relative to the calcium salt dissolved in water in the first step S1 to obtain a second aqueous solution (hydroxide ion aqueous solution) L2. The third step is a step of mixing the first aqueous solution (calcium ion aqueous solution) L1 and the second aqueous solution (hydroxide ion aqueous solution) L2.

[0036] Furthermore, in the first step S1 of the method for producing an aqueous calcium hydroxide solution of the present invention, it is more preferable to dissolve amino acids in water in addition to the calcium salt and sugars mentioned above.

[0037] The method for producing an aqueous calcium hydroxide solution of the present invention can be carried out using the "raw material combination set for aqueous calcium hydroxide solution" of the present invention, which will be described later. Of course, as long as the process includes the three steps 1 to 3 described above, it falls within the technical scope of the present invention, regardless of whether the "raw material combination set for aqueous calcium hydroxide solution" is used or not.

[0038] [Step 1] In the first step S1, a calcium salt, sugars, and preferably an additive such as an amino acid are dissolved in water to obtain a first aqueous solution (calcium ion aqueous solution) L1.

[0039] (Calcium salts) As for calcium salts, calcium ions (Ca 2+ Various calcium compounds that dissolve in water can be used as calcium salts. However, it is preferable to use calcium chloride (CaCl2), calcium bromide (CaBr2), calcium acetate, calcium lactate, or calcium gluconate, which have superior solubility in water compared to calcium oxide and calcium carbonate (CaCO3). Among these, it is even more preferable to use calcium chloride (CaCl2) (or calcium chloride dihydrate (CaCl2·2H2O)) as the calcium salt.

[0040] By using calcium chloride (CaCl2), more preferably calcium chloride dihydrate (CaCl2·2H2O), as the calcium salt, the water molecule clusters are reorganized into even smaller water molecule clusters. This enhances the reducing properties of the calcium hydroxide aqueous solution produced by the present invention, allowing for easy and highly accurate impartation of excellent antioxidant (reducing) properties. Furthermore, from an economic standpoint, it is preferable to select calcium chloride dihydrate (CaCl2·2H2O), which is the least expensive of the various calcium sources mentioned above.

[0041] (Sugars) Herein, in this specification, "sugars" added as essential components to the first aqueous solution refer to monosaccharides or disaccharides. These sugars promote the dissolution of calcium salts in aqueous solutions. Monosaccharides such as glucose and galactose, as well as sucrose and commercially available disaccharides such as granulated sugar, refined sugar, and medium-white sugar, contribute to improved solubility. Among these, it is particularly preferable to use sucrose, which contributes most significantly to improving solubility.

[0042] However, in implementing the present invention, it is not excluded that, in addition to "sugars" in the sense described above, i.e., monosaccharides and disaccharides as exemplified above, "polysaccharides" for the purpose of imparting a moisturizing effect may be added to the aqueous calcium hydroxide solution. A process of adding polysaccharides in a manner that does not hinder the effects of the present invention is naturally within the scope of the present invention.

[0043] (amino acid) The reducing properties can be improved by adding amino acids to the first aqueous solution. Cysteine ​​is a preferred amino acid. Cysteine ​​can be used in various forms, such as the L-form, D-form, DL-form, or cysteine ​​hydrochloride monohydrate, without any particular restrictions, but from an economic standpoint, it is preferable to use L-cysteine ​​or L-cysteine ​​hydrochloride monohydrate.

[0044] (Other additives) In addition to the first aqueous solution, other alkaline and stable reducing compounds may be added as needed. Examples of other additives include polyphenols, tannic acid, gallic acid, and the like.

[0045] [Step 2] In the second step S2, an alkali metal hydroxide is dissolved in water to obtain a second aqueous solution (hydroxide ion aqueous solution) L2.

[0046] The amount of alkali metal hydroxide added to the second aqueous solution (hydroxide ion aqueous solution) L2 is 25% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 100% by mass or less, and most preferably 60% by mass or more and 100% by mass or less, relative to the calcium salt dissolved in water in the first step. Alternatively, the amount of alkali metal hydroxide added may be adjusted so that the hydroxide ions in the first aqueous solution L1 are 60 mol% or more and 270 mol% in molar ratio to calcium ions.

[0047] (Alkali metal hydroxides) Potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiOH), and the like can be preferably used as the alkali metal hydroxide in the second step S2.

[0048] [Third step] In the third step S3, a calcium hydroxide aqueous solution can be obtained by mixing the first aqueous solution (calcium ion aqueous solution) L1 and the second aqueous solution (hydroxide ion aqueous solution) L2 obtained in the above-mentioned steps. Specifically, a calcium hydroxide aqueous solution can be produced by adding the second aqueous solution (hydroxide ion aqueous solution) L2 to a container containing the first aqueous solution (calcium ion aqueous solution) L1 at an appropriate rate and mixing them to dissolve both in the aqueous solution.

[0049] Furthermore, in the third step S3, it is preferable that the container for mixing the two liquids be made of resin. By using a resin container, it is possible to avoid the erosion of the glass surface that may occur when using a glass bottle.

[0050] [Calcium hydroxide solution raw material combination set] To carry out the method for producing an aqueous calcium solution of the present invention, the "raw material combination set for aqueous calcium hydroxide solution" of the present invention can be preferably used. This raw material combination set is a two-liquid mixed type raw material combination set comprising a first aqueous solution L1 and a second aqueous solution L2, which are described in detail above, and is intended for use in the production of an aqueous calcium hydroxide solution.

[0051] The "raw material combination set for calcium hydroxide aqueous solution" of the present invention, which comprises a first aqueous solution L1 and a second aqueous solution L2, is an optimal combination of chemical substances that can be obtained stably and in large quantities. By using this set as a material for the "method for producing calcium hydroxide aqueous solution" of the present invention, economic problems such as high equipment costs and high equipment operating costs during production can be solved. Furthermore, this eliminates the need for the time and cost required to secure and prepare natural materials such as seashells. Therefore, by using the "raw material combination set for calcium hydroxide aqueous solution" of the present invention, it becomes possible to mass-produce extremely low-cost reducing solutions and distribute them to the market cheaply and explosively. [Examples]

[0052] The present invention will be further described below with reference to examples relating to the "method for producing an aqueous calcium hydroxide solution" of the present invention, but the present invention is not limited to the following examples.

[0053] (First step) The "first step," which is an essential step in the method for producing an aqueous calcium hydroxide solution of the present invention, was carried out as follows. Calcium chloride dihydrate (molecular weight 147.01) was used as the calcium salt. Sucrose (molecular weight 342.30) was used as the sugar, and L-cysteine ​​hydrochloride monohydrate (175.63) was used as the amino acid. However, only in Example 3, glucose (molecular weight 180.2) was used instead of sucrose as the sugar. These were then dissolved in purified water to obtain the first aqueous solution. The amount of each agent added per 100 ml of purified water for each example and comparative example is shown in Table 1 below.

[0054] (Second step) Similarly, the "second step" was carried out as follows. Potassium hydroxide (molecular weight 56.11) was used as the alkali metal hydroxide. A second aqueous solution was obtained by dissolving this in purified water. The amount of alkali metal hydroxide added per 100 ml of purified water for each example and comparative example is shown in Table 1 below.

[0055] (Third step) Then, the "third step" was carried out by adding 5,000 ml of the second aqueous solution obtained in the "second step" to a resin reaction vessel containing 5,000 ml of the first aqueous solution obtained in the "first step" above, in a manner in which the entire amount was added dropwise over a period of about 30 minutes.

[0056] (Evaluation of calcium hydroxide solution) The amount of Ca(OH)2 produced (%) and the oxidation-reduction potential (m) of the calcium hydroxide solutions of the examples and comparative examples obtained in the "third step" described above. V The presence or absence of precipitate formation when the second aqueous solution is added dropwise was compared and evaluated.

[0057] The amount of Ca(OH)2 produced (%) is a theoretical value calculated from the chemical equivalents of each agent, but an appropriate amount of alkali metal hydroxide is added to the second aqueous solution. Ta From Example 1 5 In this method, no precipitate was formed, and a calcium hydroxide solution with a sufficient calcium ion concentration was quickly produced.

[0058] Oxidation-reduction potential (m V The measurement was performed using the "ORP simultaneous measurement device attached to the HM50V pH meter manufactured by Toa Denpa Kogyo Co., Ltd."

[0059] The presence or absence of precipitate formation was evaluated visually. In Comparative Example 1, the only difference from Example 3, in which no precipitate formed, was that no sugars were added to the first aqueous solution. The formation of a white precipitate derived from calcium hydroxide was confirmed.

[0060] (Evaluation of sugar selection) In Example 3, when the monosaccharide "glucose" was used instead of "sucrose" as the sugar, there was no significant change in the quality (reducing power) of the calcium hydroxide aqueous solution produced in the third step. However, when the sugar was added in the first step, the first aqueous solution temporarily turned brown. It has been confirmed that this phenomenon does not occur when "sucrose" is used.

[0061] [Table 1]

[0062] From the evaluation results above, it can be seen that, according to the present invention, it is possible to mass-produce an aqueous calcium hydroxide solution at low cost and stably through a process that allows the reaction to proceed solely through pure chemical reactions. [Explanation of Symbols]

[0063] S1 First process S2 Second process S3 Third Process L1 First aqueous solution (calcium ion aqueous solution) L2 Second aqueous solution (hydroxide ion aqueous solution)

Claims

1. The first step involves dissolving a calcium salt, sugars, and amino acids in water to obtain a calcium ion aqueous solution as the first aqueous solution. In the second step, an alkali metal hydroxide in a mass ratio of 25% to 100% relative to the calcium salt dissolved in water in the first step is dissolved in water in a container separate from the one used in the first step to obtain a second aqueous solution of hydroxide ions. A third step is performed, in which the first aqueous solution and the second aqueous solution are mixed in the same container to obtain an aqueous calcium hydroxide solution. A method for producing an aqueous calcium hydroxide solution.

2. A set of raw material combinations for calcium hydroxide aqueous solution, A first aqueous solution is a calcium ion aqueous solution containing calcium salts, sugars, and amino acids, The solution comprises a second aqueous solution, which is an aqueous calcium hydroxide solution containing an alkali metal hydroxide in a mass ratio of 25% to 100% of the calcium salt contained in the first aqueous solution, A set of raw materials for a two-part calcium hydroxide solution.

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