Aqueous acrylamide solution and method for stabilizing aqueous acrylamide solution

Abstract

The acrylamide aqueous solution comprises water, acrylamide and an aliphatic amine compound.

Description

Technical Field

[0001] The present disclosure relates to an aqueous acrylamide solution and a method for stabilizing the aqueous acrylamide solution. Background Art

[0002] Acrylamide, which is a raw material for polyacrylamide, is usually circulated in the market in the form of powder or aqueous solution.

[0003] The following problems have been pointed out: If the aqueous acrylamide solution is stored for a long time, the polymerization reaction of acrylamide will proceed in the aqueous solution. Therefore, various measures have been tried to suppress the polymerization reaction of acrylamide in the aqueous solution. For example, Patent Document 1 discloses the use of 2,2,6,6-tetramethyl-1-piperidinyloxy radical and manganese ions to suppress the polymerization reaction of acrylamide in the aqueous solution and improve the stability of the aqueous acrylamide solution.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: International Publication No. 2012 / 157776 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] If an aqueous acrylamide solution with improved stability by a hitherto unknown method is found, it will bring various options for the treatment form of acrylamide and significantly promote the development of the industry.

[0009] In view of the above circumstances, an object of the present disclosure is to provide a novel aqueous acrylamide solution and a method for stabilizing the aqueous acrylamide solution.

[0010] Means for Solving the Problems

[0011] Means for solving the above problems include the following embodiments.

[0012] <1> An aqueous acrylamide solution comprising water, acrylamide, and an aliphatic amine compound.

[0013] <2> The aqueous acrylamide solution according to <1>, wherein the aliphatic amine compound contains at least one selected from putrescine, spermidine, and spermine.

[0014] <3> The aqueous acrylamide solution according to <1> or <2>, wherein the amount of the aliphatic amine compound is 0.02 mg to 10 mg relative to 1 kg of the acrylamide.

[0015] <4> The acrylamide aqueous solution according to any one of <1> to <3>, wherein the content rate of the aforementioned acrylamide is 30% by mass to 60% by mass of the whole acrylamide aqueous solution.

[0016] <5> A method for stabilizing an acrylamide aqueous solution, which includes adding an aliphatic amine compound to an acrylamide aqueous solution containing water and acrylamide.

[0017] <6> The method for stabilizing an acrylamide aqueous solution according to <5>, wherein the aforementioned aliphatic amine compound contains at least 1 kind selected from putrescine, spermidine, and spermine.

[0018] <7> The method for stabilizing an acrylamide aqueous solution according to <5> or <6>, wherein, relative to 1 kg of the aforementioned acrylamide, the amount of the aforementioned aliphatic amine compound is 0.02 mg to 10 mg.

[0019] <8> The method for stabilizing an acrylamide aqueous solution according to any one of <5> to <7>, wherein the content rate of the aforementioned acrylamide is 30% by mass to 60% by mass of the whole acrylamide aqueous solution.

[0020] Effects of the Invention

[0021] According to the present disclosure, a novel acrylamide aqueous solution and a method for stabilizing an acrylamide aqueous solution are provided. Detailed Description

[0022] In this specification, the numerical range indicated by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0023] In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range can be replaced with the upper limit value or the lower limit value of another stepwise described numerical range. In addition, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of this numerical range can be replaced with the value shown in the examples.

[0024] In the present disclosure, each component may contain a plurality of corresponding substances. In the present disclosure, when referring to the amount of each component in the composition, when there are a plurality of substances belonging to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition.

[0025] <Acrylamide Aqueous Solution>

[0026] One aspect of the present disclosure is an acrylamide aqueous solution, which contains water, acrylamide, and an aliphatic amine compound.

[0027] As shown in the results of the examples described below, an aqueous acrylamide solution containing an aliphatic amine compound can suppress the polymerization of acrylamide for a long period of time as compared with an aqueous acrylamide solution containing an aliphatic amine compound.

[0028] In the present disclosure, the "aliphatic amine compound" refers to a compound formed from one or more amino groups and one or more aliphatic hydrocarbon groups.

[0029] The aliphatic hydrocarbon group contained in the aliphatic amine compound may be cyclic or acyclic, preferably acyclic, more preferably linear.

[0030] The aliphatic hydrocarbon group contained in the aliphatic amine compound may contain an unsaturated bond or may not contain an unsaturated bond, preferably does not contain an unsaturated bond.

[0031] The number of carbon atoms contained in the aliphatic amine compound is not particularly limited. From the viewpoint of the stabilization effect of the aqueous acrylamide solution, the number of carbon atoms contained in the aliphatic amine compound is preferably 2 to 30, preferably 3 to 15, more preferably 4 to 12.

[0032] The number of amino groups contained in the aliphatic amine compound is not particularly limited as long as it is 1 or more. From the viewpoint of the stabilization effect of the aqueous acrylamide solution, the number of amino groups contained in the aliphatic amine compound is preferably 2 or more. The number of amino groups contained in the aliphatic amine compound is preferably 6 or less, more preferably 4 or less.

[0033] The amino group contained in the aliphatic amine compound may be any of a primary amino group, a secondary amino group, or a tertiary amino group. From the viewpoint of the stabilization effect of the aqueous acrylamide solution, it is preferred that at least one of the amino groups contained in the aliphatic amine compound is a primary amino group.

[0034] The aliphatic amine compound contained in the aqueous acrylamide solution may be only one kind or two or more kinds.

[0035] From the viewpoint of the stabilization effect of the aqueous acrylamide solution, the aliphatic amine compound preferably contains a compound represented by the following formula.

[0036] [Chemical formula 1]

[0037]

[0038] In the formula, R is an alkylene group, and n is a number from 0 to 4.

[0039] From the viewpoint of the stabilization effect of the aqueous acrylamide solution, R is preferably an alkylene group having 2 to 6 carbon atoms, more preferably an alkylene group having 3 or 4 carbon atoms. The alkylene group is preferably linear.

[0040] From the viewpoint of the stabilization effect of the aqueous acrylamide solution, n is preferably from 0 to 3, more preferably from 0 to 2.

[0041] Specific examples of the compound represented by the above formula include putrescine (a compound in which R is an alkylene group having 4 carbon atoms and n is 0), spermidine (a compound in which R is an alkylene group having 4 carbon atoms and n is 1), and spermine (a compound in which R is an alkylene group having 4 carbon atoms and n is 2). The aqueous acrylamide solution may contain one or more of the compounds represented by the formula.

[0042] The form of the aliphatic amine compound is not particularly limited. For example, it may be a free form as shown by the above structural formula or in a salt state. Specific examples of the salt of the aliphatic amine compound include phosphate, bromide salt, hydrochloride salt, etc.

[0043] The amount of the aliphatic amine compound contained in the aqueous acrylamide solution is preferably 0.02 mg or more, more preferably 0.1 mg or more, per 1 kg of acrylamide contained in the aqueous acrylamide solution.

[0044] The amount of the aliphatic amine compound contained in the aqueous acrylamide solution is preferably 10 mg or less, more preferably 1.0 mg or less, per 1 kg of acrylamide contained in the aqueous acrylamide solution.

[0045] If the amount of the aliphatic amine compound is in the range of 0.02 mg to 10 mg per 1 kg of acrylamide, a sufficient stabilization effect of the aqueous acrylamide solution can be obtained.

[0046] The content rate of acrylamide contained in the aqueous acrylamide solution is not particularly limited.

[0047] From the viewpoint of economy, the content rate of acrylamide is preferably 30% by mass or more, more preferably 35% by mass or more, further preferably 40% by mass or more, of the whole aqueous acrylamide solution.

[0048] From the viewpoint of the stability of the aqueous acrylamide solution, the content rate of acrylamide is preferably 60% by mass or less, more preferably 55% by mass or less, more preferably 50% by mass or less, of the whole aqueous acrylamide solution.

[0049] If necessary, the aqueous acrylamide solution may contain components other than the aliphatic amine compound. For example, the aqueous acrylamide solution may contain stabilizers, pH adjusters, etc. other than the aliphatic amine compound.

[0050] The aqueous acrylamide solution may be an aqueous solution obtained by dissolving acrylamide in water, or may be a state in which the synthesized acrylamide is contained in the water used in the synthesis of acrylamide. That is, the water contained in the aqueous acrylamide solution may include the water used in the synthesis of acrylamide, for example, the water used in the hydration of acrylonitrile to synthesize acrylamide.

[0051] The method for synthesizing acrylamide by hydration of acrylonitrile is not particularly limited, and can be selected from known methods such as biocatalytic method, copper-catalyzed method, acid-catalyzed method, sulfuric acid hydration method, etc. Among these, from the viewpoints of the purity of the obtained acrylamide, production efficiency, etc., the biocatalytic method is preferred.

[0052] In the present disclosure, the biocatalytic method refers to a method in which acrylonitrile is hydrated using nitrile hydratase, which is a kind of enzyme, as a catalyst to obtain acrylamide.

[0053] Nitrile hydratase is an enzyme having an activity of converting a nitrile group into an amide group by hydration (nitrile hydrating activity).

[0054] The nitrile hydratase used in the synthesis of acrylamide may be a nitrile hydratase produced by microorganisms or a nitrile hydratase synthesized artificially.

[0055] As the microorganisms for producing nitrile hydratase, specifically, microorganisms belonging to the following genera can be cited: Nocardia, Corynebacterium, Bacillus, Thermophilic Bacillus, Pseudomonas, Micrococcus, Rhodococcus represented by Rhodochrous species, Acinetobacter, Xanthobacter, Streptomyces, Rhizobium, Klebsiella, Enterobacter, Erwinia, Aeromonas, Citrobacter, Achromobacter, Agrobacterium, Pseudonocardia represented by Thermophila species, Bacteridium, and Brevibacterium.

[0056] The nitrile hydratase may also be a modified nitrile hydratase obtained by modifying a nitrile hydratase produced by a microorganism. As the modified nitrile hydratase, there can be mentioned a modified nitrile hydratase obtained by substituting, deleting, removing or inserting a part of amino acid residues (for example, one or more than two amino acid residues) contained in the amino acid sequence of a nitrile hydratase produced by a microorganism, thereby improving characteristics such as amide compound tolerance, nitrile compound tolerance, and temperature tolerance.

[0057] <Method for stabilizing an aqueous acrylamide solution>

[0058] One aspect of the present disclosure is a method for stabilizing an aqueous acrylamide solution, which includes adding an aliphatic amine compound to an aqueous acrylamide solution containing water and acrylamide.

[0059] As shown by the results of the following examples, when an aliphatic amine compound is added to an aqueous acrylamide solution, the polymerization of acrylamide can be inhibited for a long time as compared with the case where no aliphatic amine compound is added to the aqueous acrylamide solution.

[0060] The details and preferred modes of the aqueous acrylamide solution and the aliphatic amine compound used in the method for stabilizing an aqueous acrylamide solution are the same as the details and preferred modes of the above-mentioned aqueous acrylamide solution and the aliphatic amine compound.

[0061] As needed, the above method may include adding components other than the aliphatic amine compound to the aqueous acrylamide solution. For example, it may include adding stabilizers, pH adjusters, etc. other than the aliphatic amine compound to the aqueous acrylamide solution.

[0062] Examples

[0063] Hereinafter, the embodiments will be further specifically described based on examples, but the present disclosure is not limited by any of them.

[0064] An experiment was conducted to evaluate the stability of an aqueous acrylamide solution by the production state of a polymer of acrylamide in an aqueous acrylamide solution stored at 37°C. Specifically, a methanol test was conducted to measure the number of days until the light transmittance of the aqueous acrylamide solution at 360 nm was lower than a specified level, and the stability was evaluated based on the results.

[0065] In the methanol test, a sample of the aqueous acrylamide solution was mixed with methanol (FUJIFILM Wako Pure Chemical Corporation, reagent special grade) at a volume ratio of 1:9, and the light transmittance T% at 360 nm was measured. In the experiment, a quartz cell (optical path length: 1 cm) and a detector (SHIMADZU UV-1800, Shimadzu Corporation) were used.

[0066] <Comparative Example 1>

[0067] An aqueous solution of acrylamide prepared by biocatalysis (acrylamide content: 50% by mass, Mitsui Chemicals, Inc.) was taken. This aqueous acrylamide solution was placed in a 50-ml polyethylene container, sealed, and left standing in a constant-temperature bath at 37°C. A methanol test was performed every day, and the light transmittance at 360 nm was measured. The number of days elapsed from the start of the test until the light transmittance dropped below 99.00% is shown in Table 1.

[0068] To investigate whether the aqueous acrylamide solution used in Comparative Example 1 contained compounds belonging to aliphatic amines, HPLC analysis was performed under the following conditions. As a result, the concentration of compounds belonging to aliphatic amines was below the detection limit.

[0069] Apparatus: High-performance liquid chromatography system (JASCO Corporation) and fluorescence detector (JASCO Corporation)

[0070] Eluent composition: 10 mM phosphoric acid, 25 vol% acetonitrile, 2 g / L sodium 1-octanesulfonate

[0071] Chromogenic solution composition: 12 mM o-phthalaldehyde, 2 g / L N-acetyl-L-cysteine, 3 vol% ethanol, 0.2 mol / L boric acid, 0.04% Briji-35, pH 10.5

[0072] Analysis column: Develosil ODS-MG (Nomura Chemical Co., Ltd.), 4.6×250 mm, 5 μm

[0073] Column temperature: 40°C

[0074] Fluorescence detection: Ex 365 nm, Em 455 nm

[0075] Eluent flow rate: 0.8 ml / min

[0076] Chromogenic solution flow rate: 0.4 ml / min

[0077] <Example 1>

[0078] 100 mg of putrescine dihydrochloride (FUJIFILM Wako Pure Chemical Corporation, standard content 99%) was dissolved in ultrapure water to prepare a 1-mg / ml aqueous putrescine solution. The prepared aqueous putrescine solution was added to the aqueous acrylamide solution used in Comparative Example 1 such that the amount of putrescine was 10 mg per 1 kg of acrylamide. Then, the same operation as in Comparative Example 1 was performed, and the methanol test was carried out. The results are shown in Table 1.

[0079] <Example 2>

[0080] Except for adding an aqueous putrescine solution to the aqueous acrylamide solution in such a manner that the amount of putrescine is 2 mg relative to 1 kg of acrylamide, the methanol test was conducted in the same manner as in Example 1. The results are shown in Table 1.

[0081] <Example 3>

[0082] Except for adding an aqueous putrescine solution to the aqueous acrylamide solution in such a manner that the amount of putrescine is 1 mg relative to 1 kg of acrylamide, the methanol test was conducted in the same manner as in Example 1. The results are shown in Table 1.

[0083] <Example 4>

[0084] The 1 mg / ml aqueous putrescine solution was diluted with ultrapure water to prepare a 0.01 mg / ml aqueous putrescine solution. An aqueous putrescine solution diluted in such a manner that the amount of putrescine is 0.2 mg relative to 1 kg of acrylamide was added to the aqueous acrylamide solution, and except for this, the methanol test was conducted in the same manner as in Example 1. The results are shown in Table 1.

[0085] <Example 5>

[0086] The 1 mg / ml aqueous putrescine solution was diluted with ultrapure water to prepare a 0.01 mg / ml aqueous putrescine solution. An aqueous putrescine solution diluted in such a manner that the amount of putrescine is 0.1 mg relative to 1 kg of acrylamide was added to the aqueous acrylamide solution, and except for this, the methanol test was conducted in the same manner as in Example 1. The results are shown in Table 1.

[0087] <Example 6>

[0088] The 1 mg / ml aqueous putrescine solution was diluted with ultrapure water to prepare a 0.01 mg / ml aqueous putrescine solution. An aqueous putrescine solution diluted in such a manner that the amount of putrescine is 0.02 mg relative to 1 kg of acrylamide was added to the aqueous acrylamide solution, and except for this, the methanol test was conducted in the same manner as in Example 1. The results are shown in Table 1.

[0089] [Table 1]

[0090]

[0091] As shown in Table 1, the acrylamide aqueous solutions of Examples 1 to 6 to which putrescine was added had a longer number of days until the light transmittance at 360 nm was lower than 99.00% compared to the acrylamide aqueous solution of Comparative Example 1 to which no putrescine was added, and the stability of the acrylamide aqueous solution was excellent.

[0092] <Comparative Example 2>

[0093] Dissolve 5 g of acrylamide (Sigma Aldrich, purity above 99%) in 5 g of ultrapure water to prepare an acrylamide aqueous solution with an acrylamide content of 50% by mass. Add this acrylamide aqueous solution to a 50-ml polyethylene container, seal it, and let it stand in a constant-temperature bath at 37°C. Conduct a methanol test every day and measure the light transmittance at 360 nm. The number of days elapsed from the start of the test until the light transmittance is lower than 99.90% is shown in Table 2.

[0094] <Example 7>

[0095] Dissolve 100 mg of putrescine dihydrochloride (FUJIFILM Wako Pure Chemical Corporation, standard content 99%) in ultrapure water to prepare a 1-mg / ml putrescine aqueous solution. Add the prepared putrescine aqueous solution to the acrylamide aqueous solution prepared in Comparative Example 2 such that the amount of putrescine is 2 mg relative to 1 kg of acrylamide. Then, perform the methanol test in the same manner as in Comparative Example 2. The results are shown in Table 2.

[0096] <Reference Example 1>

[0097] Dissolve 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO, FUJIFILM Wako Pure Chemical Corporation, standard content 98%) in ultrapure water to prepare a 0.4-mg / ml TEMPO aqueous solution.

[0098] Dissolve manganese sulfate pentahydrate (FUJIFILM Wako Pure Chemical Corporation, reagent special grade) in ultrapure water and dilute it to prepare a 0.4-mg / ml manganese sulfate aqueous solution.

[0099] Add the TEMPO aqueous solution and the manganese sulfate aqueous solution to the acrylamide aqueous solution prepared in Comparative Example 2 such that the amount of TEMPO is 2 mg relative to 1 kg of acrylamide and the amount of manganese sulfate is 2 mg relative to 1 kg of acrylamide, respectively. Then, perform the methanol test in the same manner as in Comparative Example 2. The results are shown in Table 2.

[0100] <Reference Example 2>

[0101] Add the TEMPO aqueous solution and the manganese sulfate aqueous solution to the acrylamide aqueous solution prepared in Comparative Example 2 such that the amount of TEMPO is 2 mg relative to 1 kg of acrylamide and the amount of manganese sulfate is 0.2 mg relative to 1 kg of acrylamide, respectively. Then, perform the methanol test in the same manner as in Comparative Example 2. The results are shown in Table 2.

[0102] [Table 2]

[0103]

[0104] As shown in Table 2, the aqueous acrylamide solution of Example 7 to which putrescine was added had a longer number of days until the light transmittance at 360 nm was lower than 99.90% compared to the aqueous acrylamide solution of Comparative Example 2 to which no putrescine was added, and the stability of the aqueous acrylamide solution was excellent.

[0105] In addition, the aqueous acrylamide solution of Example 7 to which putrescine was added had a longer number of days until the light transmittance at 360 nm was lower than 99.90% compared to the aqueous acrylamide solutions of Reference Examples 1 and 2 to which TEMPO and manganese ions, which were described as stabilizers in the reported literature, were added, and the stability of the aqueous acrylamide solution was more excellent.

Claims

1. An aqueous acrylamide solution comprising water, acrylamide, and an aliphatic amine compound.

2. The aqueous acrylamide solution according to claim 1, wherein the aliphatic amine compound comprises at least one selected from the group consisting of putrescine, spermidine, and spermine.

3. The aqueous acrylamide solution according to claim 1, wherein with respect to 1 kg of the acrylamide, the amount of the aliphatic amine compound is 0.02 mg to 10 mg.

4. The aqueous acrylamide solution according to claim 1, wherein the content of the acrylamide is 30% by mass to 60% by mass of the entire aqueous acrylamide solution.

5. A method for stabilizing an aqueous acrylamide solution, which comprises adding an aliphatic amine compound to an aqueous acrylamide solution containing water and acrylamide.

6. The method for stabilizing an aqueous acrylamide solution according to claim 5, wherein the aliphatic amine compound comprises at least one selected from the group consisting of putrescine, spermidine, and spermine.

7. The method for stabilizing an aqueous acrylamide solution according to claim 5, wherein with respect to 1 kg of the acrylamide, the amount of the aliphatic amine compound is 0.02 mg to 10 mg.

8. The method for stabilizing an aqueous acrylamide solution according to claim 5, wherein the content of the acrylamide is 30% by mass to 60% by mass of the entire aqueous acrylamide solution.

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