Basic aluminum lactate solution

Abstract

An object is to develop a basic aluminum lactate solution having excellent storage stability. 【Solution means】The solution means is a basic aluminum lactate solution that satisfies the following requirements (1) to (2). That is, (1) it contains L-lactic acid, which is an optical isomer of lactic acid, and D-lactic acid, which is a D-isomer, and the ratio of D-lactic acid in total lactic acid (L-lactic acid + D-lactic acid) is in the range of 3 to 99 mol%; and (2) the range of total lactic acid / Al2O3 (molar ratio) = 1.0 to 4.0.

Description

Technical Field

[0001] The present invention relates to a basic aluminum lactate solution.

Background Art

[0002] Basic aluminum lactate solutions have been used, for example, as additives for alkaline refractories to improve air permeability, to suppress the digestion of basic aggregates, or as aluminum dopants for raw materials of composite oxides.

[0003] There are many known documents regarding basic aluminum lactate solutions, including Patent Document 1. Although not specified in most of the documents, basic aluminum lactate solutions are somewhat difficult in storage stability and tend to precipitate when stored for a long time.

[0004] In order to maintain long-term stability, Patent Document 2 discloses an invention regarding a basic aluminum lactate solution added with malic acid.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to develop a basic aluminum lactate solution having excellent storage stability by a method different from that of Patent Document 2.

Means for Solving the Problems

[0007] As a result of intensive studies on the above problems, the inventors have found, quite surprisingly, that a basic aluminum lactate solution having long-term stability can be obtained by containing L-lactic acid (L-lactic acid) and D-lactic acid (D-lactic acid), which are optical isomers of lactic acid, in a predetermined ratio as lactic acid, and have completed the present invention based on such findings.

[0008] The present invention is as follows. [1] A basic aluminum lactate solution satisfying the following requirements (1) to (2). (1) It contains L-lactic acid (L-lactic acid), which is an optical isomer, and D-lactic acid (D-lactic acid), and the ratio of D-lactic acid in total lactic acid (L-lactic acid + D-lactic acid) is in the range of 3 to 99 mol%. (2) The range of total lactic acid / Al2O3 (molar ratio) = 1.0 to 4.0. [2] The basic aluminum lactate solution according to [1] above, in which the aluminum index is in the range of 0.90 to 1.10 in the following storage test. [Storage test] As the Al2O3 concentration before the test, measure the Al2O3 concentration of the basic aluminum lactate solution before the storage test. Measure 20 g of the above basic aluminum lactate solution into a 50 mL I-Boy PP wide-mouth bottle sold by AS ONE Corporation, seal it, and let it stand in a constant temperature bath set at 50°C for 3 weeks. Then, measure the Al2O3 concentration of the portion from the upper surface to a depth of 5 mm, and use it as the Al2O3 concentration after the test. Calculate the aluminum index from the following formula. Aluminum index = Al2O3 concentration after the test ÷ Al2O3 concentration before the test [3] A method for producing the basic aluminum lactate solution according to [1] or [2] above, including the step of mixing alumina hydrate and lactic acid. [4] A powder obtained by drying the basic aluminum lactate solution according to [1] or [2] above.

Mode for carrying out the invention

[0009] Hereinafter, the present invention will be described in detail based on preferred embodiments. However, the present invention is not limited to the following embodiments, and various modifications are possible within the scope shown in the claims. In the present invention, the notation "numerical value 1 to numerical value 2" regarding a numerical range means a numerical range including both numerical values 1 and 2, with numerical value 1 as the lower limit value and numerical value 2 as the upper limit value, and is synonymous with "numerical value 1 or more and numerical value 2 or less".

[0010] The present invention relates to a basic aluminum lactate solution satisfying the following requirements (1) to (2). (1) It contains L-lactic acid which is an optical isomer of lactic acid and D-lactic acid which is the D-isomer, and the proportion of D-lactic acid in the total lactic acid (L-lactic acid + D-lactic acid) is in the range of 3 to 99 mol%. (2) The range of total lactic acid / Al2O3 (molar ratio) = 1.0 to 4.0.

[0011] (Requirement 1) Lactic acid has L-form and D-form as optical isomers, which are called L-lactic acid and D-lactic acid respectively. In the literature, if it is simply described as "lactic acid", it is common technical knowledge to be understood as intended for L-lactic acid. Generally, when it is described as "L-lactic acid", it is often when it is necessary to distinguish from D-lactic acid.

[0012] The basic aluminum lactate solution of the present invention contains L-lactic acid and D-lactic acid as lactic acid, and the proportion of D-lactic acid in the total lactic acid, that is, [L-lactic acid + D-lactic acid] (hereinafter referred to as "D-form ratio") is in the range of 3 to 99 mol%. When the D-form ratio is less than 3 mol% or more than 99 mol%, precipitation is likely to occur. The lower limit value of the above range is preferably 5 mol%, more preferably 7 mol%, still more preferably 8 mol%, and particularly preferably 10 mol%. Therefore, preferred ranges of the D-form ratio include 5 to 99 mol%, 7 to 99 mol%, 8 to 99 mol%, and 10 to 99 mol%.

[0013] In the present invention, the measurement method for obtaining the D-form ratio is as follows. (Treatment of basic aluminum lactate solution) In order to measure the specific rotation of lactic acid in the basic aluminum lactate solution to be measured, a treatment is carried out to dissolve aluminum in the solution in hydrochloric acid. Specifically, concentrated hydrochloric acid is added to the basic aluminum lactate solution in the range of Cl in concentrated hydrochloric acid / Al2O3 in the basic aluminum lactate solution (molar ratio) = 3 to 10, and then boiled for 10 minutes. Then, the cooled one is used as a sample for measurement. Note that in the above boiling, it is gently boiled so as not to evaporate to dryness. (Calibration curve creation) The lactic acids used to obtain the calibration curve are DL-lactic acid (a mixture of 50 mol% of L-lactic acid and D-lactic acid) and L-lactic acid. As DL-lactic acid, "DL-Lactic Acid Special Grade" (product code: 000-43525) manufactured by Kishida Chemical Co., Ltd. is used. As L-lactic acid, "L-Lactic Acid Special Grade" (product code: 129-02666) manufactured by Fujifilm Wako Pure Chemical Corporation is used. Approximately 0.5 g of each of the above DL-lactic acid and L-lactic acid is precisely weighed with an analytical balance as a guide and placed in a 100 mL volumetric flask. After adding about 20 mL of distilled water and 2 mL of concentrated hydrochloric acid, it is boiled for 10 minutes, cooled, and then made up to the mark with distilled water to prepare a standard solution. Note that in the above boiling, it is gently boiled so as not to evaporate to dryness. The discrimination of optical isomers (L-form, D-form) is carried out by measuring the specific rotation. As the measuring device, a polarimeter P-2200 manufactured by JASCO Corporation is used. Note that if a measurement value equivalent to the said measuring device can be obtained, another measuring device may be used. Using the standard solutions of DL-lactic acid and L-lactic acid prepared as above, the specific rotations are measured with the above measuring device to create a calibration curve. Next, the specific rotation of the sample is measured, and the D-form ratio of the sample is determined from the calibration curve. Note that distilled water is used for the blank measurement. In this measurement method, since a standard solution consisting only of D-lactic acid is not used, depending on the calibration curve, for example, when measuring D-lactic acid, the D-form ratio may exceed 100 mol%, but even if it does, there is no problem, and the value exceeding 100 mol% may be directly adopted. By the way, when determining the D-form ratio using the lactic acid used as the raw material as a sample, it is not necessary to add concentrated hydrochloric acid and perform heat treatment on the sample and the standard solution. On the other hand, when using the basic aluminum lactate solution as described above as a sample, by adding concentrated hydrochloric acid and performing heat treatment on the standard solution in the same manner as the sample, a D-form ratio value consistent with the D-form ratio of the lactic acid used as the raw material can be obtained.

[0014] (Requirement 2) The basic aluminum lactate solution of the present invention has a range of total lactic acid / Al2O3 (molar ratio) = 1.0 to 4.0. When the total lactic acid / Al2O3 (molar ratio) is less than 1.0, the solution stability tends to be impaired, such as precipitation being likely to occur. On the other hand, when it exceeds 4.0, a stable basic aluminum lactate solution can be obtained regardless of the ratio of the optical isomers of lactic acid, but it is not economical to contain a large amount of lactic acid.

[0015] The Al2O3 concentration of the basic aluminum lactate solution of the present invention is preferably in the range of 1 to 20% by mass. From the economic viewpoints of production and transportation, the lower limit is more preferably 3% by mass, and even more preferably 5% by mass. The upper limit is more preferably 15% by mass.

[0016] (Other components) The basic aluminum lactate solution of the present invention allows the inclusion of a sulfuric acid component, but is preferably substantially free of the sulfuric acid component. Here, being substantially free of the sulfuric acid component means that except for the sulfuric acid component derived from impurities in the raw material, no sulfuric acid component is contained. When the basic aluminum lactate solution of the present invention contains a sulfuric acid component, the content of the sulfuric acid component in the solution is preferably such that SO4 / Al2O3 (molar ratio) is less than 0.01, and more preferably less than 0.008.

[0017] In addition, the basic aluminum lactate solution of the present invention allows the inclusion of a calcium component, but is preferably substantially free of the calcium component. Here, being substantially free of the calcium component means that, excluding the calcium component derived from impurities in the raw materials, no calcium component is contained. When the basic aluminum lactate solution of the present invention contains a calcium component, the content of the calcium component in the solution is preferably such that the molar ratio of CaO / Al2O3 is less than 0.01, more preferably less than 0.008.

[0018] (Aluminum index) A preferred form of the basic aluminum lactate solution of the present invention is one in which the aluminum index is in the range of 0.90 to 1.10 in the following storage test. 〔Storage test〕 As the Al2O3 concentration before the test, measure the Al2O3 concentration of the basic aluminum lactate solution before the storage test. Measure 20 g of the basic aluminum lactate solution into a 50 mL I-Boy PP wide-mouth bottle sold by AS ONE Corporation, seal it, and let it stand in a constant temperature bath set at 50 °C for 3 weeks. Then, measure the Al2O3 concentration of the portion from the upper surface to a depth of 5 mm, and use this as the Al2O3 concentration after the test. Calculate the aluminum index from the following formula. Aluminum index = Al2O3 concentration after the test ÷ Al2O3 concentration before the test In addition, in the above, for measuring the aluminum concentration of the portion from the upper surface to a depth of 5 mm, it is preferable to collect the portion from the upper surface to a depth of 5 mm. When collecting, it is preferable to collect as gently as possible, that is, to collect carefully while suppressing fluidity as much as possible. As the collecting instrument, a pipette, a syringe, etc. are preferable.

[0019] If the aluminum index is in the range of 0.90 to 1.10, it can be evaluated that the storage stability is high because the change in the Al2O3 concentration of the basic aluminum lactate solution before and after the test is small, and long-term stability can also be expected. The lower limit of the range is preferably 0.95. The upper limit of the range is preferably 1.05. Therefore, preferable ranges can be exemplified as 0.95 to 1.10, 0.90 to 1.05, and 0.95 to 1.05.

[0020] (Powder) The basic aluminum lactate solution of the present invention may be made into a powder by drying it. The powder can be used as it is or dispersed in water. As the drying method, commonly used methods such as spray drying, static drying, and fluidized bed drying can be adopted. Regarding the drying temperature, 300°C or lower is preferable.

[0021] (Production method) A preferred production method of the basic aluminum lactate solution of the present invention includes a step of mixing an aluminum hydrate and lactic acid. The production method substantially does not contain metal elements other than aluminum and substantially does not contain acids other than lactic acid. Here, substantially not containing metal elements other than aluminum means that except for metal elements other than aluminum derived from impurities in the raw materials, no metal elements other than aluminum are contained. Also, substantially not containing acids other than lactic acid means that except for acids other than lactic acid derived from impurities and by-components in the raw materials, no acids other than lactic acid are contained.

[0022] Examples of the aluminum hydrate include commonly commercially available aluminum hydroxide, hydrates of aluminum oxide, and aluminum hydrate gels obtained by neutralization of aluminum salts, etc. Among these, those with high solubility are particularly preferable. An example of the production of the above aluminum hydrate gel is, for example, a production method in which aluminum chloride is reacted with a carbonate or bicarbonate of an alkali metal or ammonium, and the precipitated aluminum hydrate is separated and washed.

[0023] As the lactic acid, those containing L-lactic acid and D-lactic acid and having a D-isomer ratio in the range of 3 to 99 mol% are used.

[0024] The mixing ratio of the alumina hydrate and the lactic acid is set so that the total lactic acid / Al2O3 (molar ratio) is in the range of 1.0 to 4.0. The pH of the basic aluminum lactate solution of the present invention obtained thereby is generally in the range of 3 to 6.

[0025] Furthermore, if necessary, a heating step, a filtration step, a concentration adjustment step, a concentration step, etc. may be carried out. The heating temperature in the heating step is preferably, for example, 50 to 100°C. The heating time may be appropriately set according to the heating temperature, but is preferably, for example, 0 to 12 hours. In the above, a heating time of 0 hours means stopping the heating when the predetermined heating temperature is reached after starting the heating.

Examples

[0026] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[0027] (Type of lactic acid) The types of lactic acid used are as follows. · DL-lactic acid: "DL-lactic acid special grade" manufactured by Kishida Chemical Co., Ltd. (product code: 000-43525) (lactic acid concentration described in the test report issued by the company: 91.8 mass%) · L-lactic acid: "L-lactic acid special grade" manufactured by Fujifilm Wako Pure Chemical Corporation (product code: 129-02666) (lactic acid concentration described in the inspection certificate issued by the company: 88.3 mass%) · D-lactic acid: "D-lactic acid" manufactured by Corbion (lactic acid concentration described in the analysis certificate issued by the company: 92.3 mass%)

[0028] (Preparation of alumina hydrate) 1086 parts by mass of distilled water was added to 53.9 parts by mass of aluminum chloride hexahydrate as the normal salt to prepare an aluminum chloride aqueous solution (Al2O3: 1 mass%). 100 parts by mass of an aqueous ammonium carbonate solution (NH₃: 4.7% by mass) under stirring was gradually added with 1139.9 parts by mass of the above aluminum chloride aqueous solution to produce an alumina hydrate containing sub-components. This alumina hydrate containing sub-components was filtered using a centrifuge and further washed with pouring water to obtain an alumina hydrate of Al₂O₃: 11.4% by mass, NH₃: 0.06% by mass, and Cl: 0.01% by mass.

[0029] [Examples 1 - 7 and Comparative Examples 1 - 3] Common to Examples 1 - 7 and Comparative Examples 1 - 3, a basic aluminum lactate solution was prepared by the following production method. Table 1 shows the addition amounts of each raw material (alumina hydrate, lactic acid solution). The lactic acid solution was prepared by premixing the ones described in Table 1 among the above DL-lactic acid, L-lactic acid, and D-lactic acid.

[0030] [Production Method] The alumina hydrate and the lactic acid solution were mixed. Then, it was heated at 50 - 70 °C for 30 minutes and further heated at 90 °C for 1 hour to produce a basic aluminum lactate solution. Note that stirring was performed from the above mixing until the heating was completed.

[0031] Here, in the case of Example 1 for the above production method, it is as follows. First, 5.74 g of DL-lactic acid and 23.87 g of L-lactic acid were mixed (mixing ratio of D-form and L-form is 10:90) to prepare a lactic acid solution with a D-form rate of 10 mol% of the raw material charging value. 29.61 g of the above lactic acid solution was added to 163.5 g of the alumina hydrate. This mixed solution was heated at 50 - 70 °C for 30 minutes under stirring and further heated at 90 °C for 1 hour to produce the basic aluminum lactate solution of Example 1.

[0032] [Table 1]

[0033] [D-form Rate] Regarding each basic aluminum lactate solution obtained in Examples 1 - 7 and Comparative Examples 1 - 3, the D-form rate in Table 1 is the value obtained as follows. (1) Raw material charging value It is a value calculated from the mixing ratio of DL-lactic acid, L-lactic acid, and D-lactic acid used in the preparation of the raw material lactic acid solution. (2) Lactic acid solution analysis value The prepared lactic acid solution was used as a sample (hereinafter referred to as "Sample A"). 0.5 g each of the above DL-lactic acid and L-lactic acid was precisely weighed using an analytical balance as a guide, placed in a 100 mL volumetric flask, dissolved in distilled water, and then made up to the mark to prepare standard solutions of DL-lactic acid and L-lactic acid respectively. For the measurement of the specific rotation, a polarimeter P-2200 manufactured by JASCO Corporation was used and measured according to the measurement procedure. Distilled water was used for the blank measurement, and the specific rotations of the standard solutions of DL-lactic acid and L-lactic acid prepared as above were measured to create a calibration curve. The calibration curve was y = 0.3271x - 16.317 when the D-form ratio was x and the specific rotation was y. Next, the specific rotation of Sample A was measured, and the D-form ratio was determined from the above calibration curve. (3) Basic aluminum lactate solution analysis value Concentrated hydrochloric acid was added to the basic aluminum lactate solution at a Cl / Al2O3 (molar ratio) in the concentrated hydrochloric acid to the basic aluminum lactate solution of 6, and then gently boiled for 10 minutes without covering. After that, the cooled solution was used as a sample for measurement (hereinafter referred to as "Sample B"). 0.5 g each of the above DL-lactic acid and L-lactic acid was precisely weighed using an analytical balance as a guide, placed in a 100 mL volumetric flask, about 20 mL of distilled water and 2 mL of concentrated hydrochloric acid were added, and then gently boiled for 10 minutes without covering. After cooling, it was made up to the mark with distilled water to prepare a standard solution. For the measurement of the specific rotation, a polarimeter P-2200 manufactured by JASCO Corporation was used and measured according to the measurement procedure. Distilled water was used for the blank measurement, and the specific rotations of the standard solutions of DL-lactic acid and L-lactic acid prepared as above were measured to create a calibration curve. The calibration curve was y = -0.0292x + 1.5467 when the D-form ratio was x and the specific rotation was y. Next, the specific rotation of Sample B was measured, and the D-form ratio was determined from the above calibration curve.

[0034] For each basic aluminum lactate solution obtained in Examples 1 to 7 and Comparative Examples 1 to 3, the measurement methods for each analysis item described in the "Analysis Values of Basic Aluminum Lactate Solution" in Table 1 are as follows. In Comparative Example 3, since precipitation occurred in the obtained basic aluminum lactate solution, some analysis items were not analyzed. <Al2O3 Concentration> A chelometric titration method according to a conventional method was used. The outline is a method in which the basic aluminum lactate solution is dissolved with hydrochloric acid, aluminum ions are chelated with EDTA / 2Na, the pH is adjusted with sodium acetate, and then xylenol orange is used as an indicator and titrated with a zinc solution. <CaO / Al2O3 (Molar Ratio)> The calcium concentration was measured by atomic absorption spectrophotometry according to a conventional method and calculated from the above Al2O3 concentration. <SO4 / Al2O3 (Molar Ratio)> The sulfuric acid concentration was measured by a turbidimetric method using barium chloride according to a conventional method and calculated from the above Al2O3 concentration. <ph> Measured with the portable pH meter LAQUAact manufactured by Horiba, Ltd. <ec> Measured with the electrical conductivity meter CM-42X manufactured by Toa DKK Corporation. <Aluminum Index> The Al2O3 concentration before the storage test of the basic aluminum lactate solution was measured (Al2O3 concentration before the test). 20 g of the basic aluminum lactate solution was measured into a 50 mL I-Boy PP wide-mouth bottle sold by AS ONE Corporation, sealed, and allowed to stand in a thermostat set at 50°C for 3 weeks. Then, the portion from the upper surface to a depth of 5 mm was gently collected with a pipette, and the Al2O3 concentration in the collected portion was measured (Al2O3 concentration after the test). The aluminum index was calculated from the following formula. Aluminum Index = Al2O3 concentration after the test ÷ Al2O3 concentration before the test

[0035] Regarding the D-form ratio of each basic aluminum lactate solution obtained in Examples 1 to 7 and Comparative Examples 1 to 3, since the values of (1) the raw material charged value, (2) the lactic acid solution analysis value, and (3) the basic aluminum lactate solution analysis value all showed almost the same values, the analysis method was considered to be valid.

[0036] Regarding the aluminum index of each basic aluminum lactate solution obtained in Examples 1 to 7, since all were in the range of 0.90 to 1.10, they were evaluated to have high storage stability.

[0037] Regarding each basic aluminum lactate solution obtained in Examples 1 to 7 and Comparative Examples 1 to 3, although calcium components and sulfuric acid components were detected in all of them, these were considered to be derived from impurities in the raw materials.

[0038] (Powder) The basic aluminum lactate solution obtained in Example 5 was statically dried at 100°C with a ventilated dryer to obtain a powder. Ion-exchanged water was added to this powder to make the concentration the same as before drying and dissolved to obtain a solution. The properties of this solution were the same as those of the basic aluminum lactate solution before drying. The pH of this solution was 4.5 and the EC was 0.6 mS / cm.< / ec> < / ph>

Claims

1. A basic aluminum lactate solution satisfying the following requirements (1) to (2). (1) It contains L-lactic acid, which is an optical isomer of lactic acid, and D-lactic acid, which is a D-isomer, and the proportion of D-lactic acid in total lactic acid (L-lactic acid + D-lactic acid) is in the range of 3 to 99 mol%. (2) Total lactic acid / Al 2 O 3 (molar ratio) is in the range of 1.0 to 4.

0.

2. The basic aluminum lactate solution according to Claim 1, wherein the aluminum index is in the range of 0.90 to 1.10 in the following storage test. 〔Storage Test〕 Al before the test 2 O 3 As the concentration, Al before the storage test of the above basic aluminum lactate solution 2 O 3 Measure the concentration. Measure 20 g of the above basic aluminum lactate solution into a 50 mL IBOY PP wide-mouth bottle sold by AS ONE Corporation, seal it, and let it stand in a thermostatic bath set at 50°C for 3 weeks. Then, measure the Al concentration in the portion from the upper surface to a depth of 5 mm and take it as the Al concentration after the test. 2 O 3 concentration, and take it as the Al concentration after the test. 2 O 3 concentration. Calculate the aluminum index from the following formula. Aluminum index = Al 2 O 3 concentration after the test ÷ Al 2 O 3 concentration before the test

3. A process for producing a basic aluminum lactate solution according to Claim 1 or 2, comprising a step of mixing alumina hydrate and lactic acid.

4. A powder obtained by drying the basic aluminum lactate solution according to Claim 1 or 2. ​

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