JP2003277339A - Acrylamide aqueous solution containing methyl acrylate, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe acrylamide aqueous solution useful as a raw material for polyacrylamide and having a high quality. <P>SOLUTION: This acrylamide aqueous solution which releases an ester smell and can be distinguished from water due to the smell. The acrylamide aqueous solution which contains methyl acrylate, releases the ester smell, and can be distinguished from water due to the smell. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-quality and safe aqueous acrylamide solution useful as a raw material for polyacrylamide.

[0002]

2. Description of the Related Art An acrylamide aqueous solution which is usually distributed in the market is an aqueous solution containing 40 to 50% by mass of acrylamide, which is a colorless transparent and odorless liquid. Acrylamide is often used as a raw material for very high molecular weight polyacrylamide used as a coagulant for wastewater treatment, a paper strengthening agent, a petroleum recovery agent and the like.

The production method has been conventionally produced from acrylonitrile using reduced copper as a catalyst, but in recent years, a method of using a microbial enzyme in place of the copper catalyst has been developed and put into practical use. The method using a biocatalyst is extremely effective as an industrial production method because the reaction conditions are mild and there is almost no by-product, and a very simple process can be assembled.

When acrylamide is produced by using a copper catalyst, usually, unreacted acrylonitrile and a part of water are removed from a reaction solution having an acrylamide concentration of about 30% by evaporating and concentrating under reduced pressure to obtain 50% acrylamide. (JP-A-11-246498, JP-A-9-227478, JP-A-8
-157439).

Also, when acrylamide is produced using a biocatalyst, the reaction rate of the biocatalyst usually decreases in the presence of a high concentration of acrylamide, and the catalyst activity decreases (deactivates) during the reaction. After accumulating acrylamide in the reaction up to about 30 to 45%, it is concentrated by evaporation (Japanese Patent Application Nos. 11-254151 and 2000-124591).

[0006]

Acrylamide is a violent toxic substance designated as a deleterious substance, and when it comes into contact with the skin, it is easily absorbed from the skin and causes neuropathy as a local skin disorder or systemic disorder. It is said that. For this reason, the Ministry of Health, Labor and Welfare's "Regulations for the Prevention of Specified Chemical Substances" for the purpose of preventing health hazards for workers designates those containing more than 1% acrylamide as designated Class 2 substances and controls them. I am instructing them to be strict.

However, the form of acrylamide that is generally distributed industrially is an aqueous solution of 40 to 50%, and although it is a deleterious substance, these are almost indistinguishable from water in appearance. Therefore, there is a risk that acrylamide may be exposed to radiation by mistake. As a countermeasure against this, it is conceivable to add a coloring substance or a substance emitting an odor, that is, a flavoring agent to the acrylamide aqueous solution so that the acrylamide aqueous solution can be distinguished from other colorless and odorless aqueous solutions such as water. However, acrylamide, which is a raw material of acrylamide polymer used as a coagulant, a paper strengthening agent, a petroleum recovery material, etc., needs high polymerization performance, and the polymer needs high functionality. It is not possible to add odorants. Heretofore, it has been unsuccessful to add a coloring substance or a substance that emits an odor without deteriorating the function of acrylamide. The present invention avoids the risk of confusing with water without deteriorating the polymerization performance of a high-quality acrylamide aqueous solution and without changing the physical properties of a polyacrylamide polymer produced from acrylamide as a raw material. With the goal.

[0008]

[Means for Solving the Problems] The present inventors have made it possible to change the physical properties of a polyacrylamide polymer produced from acrylamide as a raw material without deteriorating the polymerization performance of a high quality acrylamide aqueous solution. However, as a result of intensive studies on a method of avoiding the risk of confusing it with water, the inventors have found that methyl acrylate is suitable as a flavoring agent and completed the present invention.

That is, the present invention provides (1) an aqueous acrylamide solution which emits an ester odor and is distinguishable from water by its odor.
(2) An acrylamide aqueous solution which emits an ester odor and is distinguishable from water by an odor, and the polymer obtained from the acrylamide aqueous solution has the same concentration as the acrylamide aqueous solution in which only acrylamide is dissolved in water. An aqueous solution of acrylamide having a viscosity equivalent to that of the obtained polymer, (3) containing methyl acrylate,
An acrylamide aqueous solution which emits an ester odor and is distinguishable from water by an odor, and (4) An acrylamide aqueous solution which contains methyl acrylate and emits an ester odor and is distinguishable from water by an odor. An aqueous solution of acrylamide whose viscosity is equal to that of a polymer obtained from an aqueous solution of acrylamide in which only acrylamide is dissolved in water, (5) 1 kg of acrylamide
(3) or (4) containing acrylamide aqueous solution, (6) containing 0.1 to 5 mg of methyl acrylate per 1 kg of acrylamide, (5) acrylamide aqueous solution, and (7) acrylamide aqueous solution containing nitrile hydratase activity. Manufactured by a biocatalyst having (1)
(6) The acrylamide aqueous solution according to any one of (6) and (8) the acrylamide aqueous solution, which is produced without undergoing an evaporative concentration operation.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The acrylamide aqueous solution referred to in the present invention is an aqueous solution containing 40 to 60 mass% of acrylamide. By adding a polymerization initiator such as ammonium persulfate to the acrylamide aqueous solution, acrylamide is polymerized to form a polyacrylamide aqueous solution. The ester odor in the present invention means
It is a sweet aroma, and the aroma emitted by ethyl acetate can be exemplified.

The acrylamide aqueous solution having an ester odor according to the present invention is equivalent in polymerization performance to an acrylamide aqueous solution having the same concentration as the acrylamide aqueous solution obtained by dissolving only acrylamide having no ester odor in water, and is obtained by polymerization. The functionality of coalescence is also similar. That is, the substances mixed to give the ester odor to the aqueous acrylamide solution have very little or no effect on the polymerization performance of the aqueous acrylamide solution or the functionality of the polymer obtained as a result of the polymerization.

The "aqueous acrylamide solution that emits an ester odor" means that the acrylamide aqueous solution contains a substance having an ester odor. Methyl acrylate is mentioned as a substance which emits an ester odor. Whether or not the aqueous acrylamide solution emits an ester odor can be determined by a sensory test method using a known panel. For example, put the acrylamide aqueous solution of the present invention in a polyethylene bag and let a few people (smellers) smell the
This can be performed by determining whether or not there is an odor.

As an acrylamide aqueous solution having an ester odor according to the present invention, methyl acrylate (1 kg) is used.
An example is an acrylamide aqueous solution containing 0.1 to 10 mg each. Generally, methyl acrylate forms a copolymer with acrylamide and may affect the polymerization performance of the acrylamide aqueous solution and the functionality of the obtained polymer, but the content of methyl acrylate in the aqueous solution of the present invention is higher than that of acrylamide. Since it is extremely low, it does not affect the polymerization performance of acrylic acid amide or the functionality of the obtained polymer.

Such an aqueous acrylamide solution containing methyl acrylate is a composition containing acrylamide and methyl acrylate, and has a novel function of being distinguishable from water by generating an ester odor. . Further, the composition is a flocculant for treating wastewater,
Paper strengthening agent, oil recovery agent, polymer coagulant, soil conditioner,
It is used as a raw material for polyacrylamide, which has applications such as thickening agents for drilling mud and polymer absorbents.

An acrylamide aqueous solution containing 0.1 to 10 mg of methyl acrylate per 1 kg of acrylamide means 1 kg of pure acrylamide contained in the acrylamide aqueous solution.
Similarly, an aqueous acrylamide solution having a mass of pure methyl acrylate contained in the aqueous acrylamide solution in the range of 0.1 to 10 mg.

If the content of methyl acrylate in a 50% acrylamide aqueous solution is less than 0.1 mg, the odor cannot be usually confirmed. Therefore, the concentration of methyl acrylate in the acrylamide aqueous solution is preferably 0.1 mg or more per 1 kg of acrylamide, and more preferably 0.3 mg or more per 1 kg of acrylamide. Further, if the content of methyl acrylate is high, it may affect the polymerization performance of the acrylamide aqueous solution or the functionality of the obtained polymer, so the concentration of methyl acrylate in the acrylamide aqueous solution is preferably 1 kg of acrylamide. 1
It is 0 mg or less, and more preferably 5 mg or less per 1 kg of acrylamide. As a preferable range of the content of methyl acrylate per 1 kg of acrylamide, 0.1-10 mg, 0.1
-5 mg, 0.3-10 mg and 0.3-5 mg can be illustrated.

The concentration of methyl acrylate in the acrylamide aqueous solution can be measured by a gas chromatography method or a liquid chromatography method, but when quantifying 10 mg or less of methyl acrylate per 1 kg of acrylamide as in the present invention, Is preferably measured after concentration by distillation, extraction or the like or after separation from acrylamide. In addition, when concentrating by distillation or extraction in this way, it is necessary to take care so that the efficiency (recovery rate) is constant, and measurement is performed using a standard solution prepared to the same acrylamide concentration as the sample. There must be.

As the acrylamide aqueous solution containing methyl acrylate in the present invention, commercially available acrylamide can be used. It is also possible to use acrylamide produced by a biocatalyst having nitrile hydrolase activity. The biocatalyst having a nitrile hydratase activity refers to a microbial cell or a treated product thereof obtained by culturing a microorganism capable of expressing the nitrile hydratase enzyme. Examples of the microorganism capable of expressing the nitrile hydratase enzyme include Bacillus genus, Bacteridium genus, Micrococcus
occus) and Brevibacterium
Genus [Japanese Patent Publication No. 62-21519], Corynebacterium
genus bacterium and genus Nocardia
56-17918], Pseudomonas genus [Japanese Patent Publication No. 59-37951], Rhodococcus genus and Microbacterium genus [Japanese Patent Publication No. 4-48]
No. 73], Rhodococcus rhodocus
odochrous) [Japanese Patent Publication No. 6-55148], Rhodococcus (Rh
Odococcus) strains [Japanese Patent Publication No. 7-40948] and the like. Further, a microorganism into which a natural or artificially improved nitrile hydratase gene has been artificially incorporated in recent years can also be used.

The above-mentioned microbial cell or a treated product thereof means the microbial cell itself which has been washed or treated with a chemical as necessary, or a crushed product of the microbial cell, a comprehensive method, a crosslinking method, a carrier of the microbial cell or the crushed cell. It is immobilized by a binding method or the like. If a biocatalyst having a nitrile hydrolase activity is used, acrylamide can be obtained without performing an evaporative concentration operation of acrylamide.

Here, the evaporative concentration operation is to evaporate the water content in acrylamide by heating or aerating under normal pressure or reduced pressure in order to further increase the acrylamide concentration in the acrylamide aqueous solution after completion of the reaction. That is. The “acrylamide aqueous solution containing 0.1 to 10 mg of methyl acrylate per 1 kg of acrylamide” of the present invention can be produced as follows.

Obtained by dissolving 500 g of commercially available acrylamide in 500 g of distilled water and adding 0.05 to 5 mg of methyl acrylate. At this time, the amount of acrylamide to be mixed is
The acrylamide content of the finally obtained aqueous solution may be set to 40 to 50% by mass by changing the range of 400 to 500 g. When the amount of acrylamide to be mixed is 400 g, the amount of methyl acrylate added may be 0.04 to 4 mg. Further, methyl acrylate may be added to a commercially available acrylamide aqueous solution. For example, it can be obtained by adding 0.05 to 5 mg of methyl acrylate to 1 L of a 50% acrylamide aqueous solution.
It is obtained by adding methyl acrylate to the thus obtained aqueous acrylamide solution according to the concentration of the acrylamide. In addition, methyl acrylate is contained in the raw material acrylonitrile at 0.13 to 1 kg per acrylonitrile.
When 13 mg is contained, it can be obtained without any particular addition.

When a biocatalyst is produced from acrylonitrile, the raw materials acrylonitrile and water and the biocatalyst are 0 to 90 # C, preferably 0 to 6
It can be obtained by contacting in a reaction tank at 0 # C, preferably 5 to 50 # C. If necessary, it is possible to add a drug having a polymerization inhibitory action, a drug contributing to the stability improvement of the catalyst, or the like to the reaction solution or the biocatalyst suspension. The reaction mode may be any of a fixed bed, a moving bed, a fluidized bed, a stirring tank, etc., and may be a batch reaction or a continuous reaction.

The acrylamide aqueous solution thus obtained may be subjected to a purification step depending on its use. Examples of the purification method include filtration with a filter (Japanese Patent Publication No. 05-49273) and purification with air bubbles (Japanese Patent Application No. 11-254151). However, refining methods (such as distillation) that separate odorous components should not be performed.

A polyacrylamide polymer can be obtained by using the polyacrylamide aqueous solution of the present invention thus obtained as a raw material. Since the amount of substances that emit ester odors such as methyl acrylate is very small, it does not affect the polymerization performance of polyacrylamide aqueous solution or the functionality of the obtained polymer, and the polymer is used as a coagulant for wastewater treatment and paper. It can be used as a strength enhancer, a petroleum recovery agent and the like.

A polyacrylamide polymer can be obtained from the acrylamido acid of the present invention by a known method.
For example, it can be carried out by adding ammonium persulfate or 4,4′-azobis- (4-cyanovaleric acid) to the acrylamide aqueous solution of the present invention. The functionality of the obtained polyacrylamide polymer can be evaluated by measuring the viscosity of the polymer using, for example, a viscometer. Specifically, it can be evaluated by measuring the Brookfield viscosity with a B type viscometer.

The functionality of the polymer obtained from the acrylamide aqueous solution of the present invention is equivalent to that of the polymer obtained from the acrylamide aqueous solution in which only acrylamide is dissolved in water. It can be evaluated by measuring the viscosity of the obtained polymer.

The viscosity of the polymer obtained from the aqueous acrylamide solution of the present invention is in the range of ± 10%, preferably ± 5% with respect to the viscosity of the aqueous acrylamide solution in which only acrylamide is dissolved. More preferably, the viscosity of the polymer obtained from the acrylamide aqueous solution of the present invention is not significantly different from the viscosity of the acrylamide aqueous solution in which only acrylamide is dissolved in water. Further, whether or not the functionality is the same can be evaluated using the amount of insoluble matter in the obtained polymer aqueous solution as an index. Preferably, the polymer aqueous solution obtained from the acrylamide aqueous solution of the present invention contains no insoluble matter.

[0028]

EXAMPLES The present invention will be specifically described by the following examples, but the present invention is not limited to these examples. Example 1 and Comparative Example 1 are those prepared from a commercially available acrylamide aqueous solution, and Example 2 and Comparative Example 2 are those prepared from acrylonitrile by using a biocatalyst to produce acrylamide.

[Example 1] (Preparation of aqueous acrylamide solution containing methyl acrylate)
A 1 L poly container was charged with 1 kg of a 50 mass% acrylamide aqueous solution (manufactured by Mitsubishi Rayon Co., Ltd.), 2.5 mg of methyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was further added, and the mixture was sealed and left at room temperature after stirring. After 10 minutes, the stopper was opened and the odor was smelled, and the smell was derived from methyl acrylate.

(Preparation of Polyacrylamide Powder) The obtained aqueous acrylamide-containing acrylamide solution was diluted with distilled water so that the concentration of acrylamide was 20% by mass, adjusted to pH 8.0, and then placed in a Dewar bottle. The liquid was transferred and the system was replaced with nitrogen. Then ammonium persulfate 0.0004
%, Iron sulfate 0.0004% by mass, and 4,4′-azobis- (4-cyanovaleric acid) 0.01% by mass were added to carry out polymerization. The obtained hydrogel polymer was crushed into particles having a diameter of several mm with a meat grinder and dried at 80 ° C. for 10 hours. 2m of this with a wheelie crusher
It was pulverized to a particle size of m or less to obtain an acrylamide polymer powder. The odor of methyl acrylate had already disappeared in this powder.

(Evaluation of Physical Properties of Polyacrylamide Powder) 1.0 g of the obtained powder was slowly added to 500 g of pure water with stirring at room temperature and dissolved for 4 hours. The Brookfield viscosity of this solution was measured using a B-type viscometer (Rotor No. 1,
Rotor speed was 30 rpm). Then, the mixture was filtered through an 80-mesh wire net, washed with water, and the weight of the insoluble matter remaining in the wire net was measured. The results are shown in Table 1.

[Comparative Example 1] A polyacrylamide powder was prepared in the same manner as in Example 1 using a 50 mass% acrylamide aqueous solution (manufactured by Mitsubishi Rayon Co., Ltd.) to which methyl acrylate was not added. Was evaluated. The results are shown in Table 1.

[0033]

[Table 1]

[Example 2] (Preparation of biocatalyst) having nitrile hydratase activity
Rhodococcus rhodochrous J1 (FERM BP-1478), glucose 2%, urea 1%, peptone 0.5%, yeast extract 0.3
%, And cobalt chloride 0.05% (both by mass), the medium (pH 7.0) was aerobically cultured at 30 ° C. 50mM this
The cells were washed with a phosphate buffer (pH 7.0) to obtain a cell suspension. On the other hand, a monomer-mixed aqueous solution was prepared such that acrylamide, methylenebisacrylamide and 2-dimethylaminopropylmethacrylamide were 30%, 1% and 4% by mass, respectively.

Subsequently, the bacterial cell suspension, the monomer aqueous solution, 10
Mass% N, N, N *, N * -tetramethylethylenediamine aqueous solution, 10 mass% ammonium persulfate aqueous solution, each 5,
After line-mixing at 2, 0.1 and 0.1 L / hr in order to polymerize, the particles were cut into particles of about 0.5 mm square to obtain immobilized bacterial cell particles. The immobilized bacterial cell particles were fluidized and washed with a 0.1% sodium acrylate aqueous solution (adjusted to pH 7) while being fluidized to obtain an immobilized bacterial cell catalyst.

(Reaction of acrylonitrile to acrylamide by immobilized bacterial cell catalyst) 3130 g of 0.2 g / L sodium acrylate aqueous solution was placed in a separable flask with a jacket having an internal volume of 5 L, and the immobilized bacterial cell catalyst 5 described above was added thereto.
g was added. While controlling the pH at 7.0 and the temperature at 15 ° C., two flat plate stirring blades having a blade length of 120 mm and a blade width of 20 mm were stirred at 80 rpm. Acrylonitrile (manufactured by Mitsubishi Rayon Co., Ltd.) was continuously fed so that the concentration of acrylonitrile was always 2% by mass, and when the concentration of acrylamide reached 47%, the feed of acrylonitrile was stopped, and then acrylonitrile was reduced to 0.005% or less. The reaction was continued until. The immobilized microbial cell catalyst was separated from this solution with a wire mesh having an opening of 100 μm to obtain 5 kg of a reaction solution having an acrylamide concentration of 50%.
The obtained aqueous acrylamide solution had an odor peculiar to methyl acrylate.

(Measurement of Methyl Acrylate Concentration) In order to measure the methyl acrylate concentration in this solution, 1 kg of the obtained reaction solution was distilled under reduced pressure of 50 mmHg while air bubbling to obtain 50 g of a distillate. It was The concentration of methyl acrylate in this distillate was measured by liquid chromatography (column:
ODS-80A (150mm, manufactured by GL Sciences Inc.), mobile phase: 5
% Aqueous solution of acetonitrile, detection: 210 nm). It was considered that 1.0 mg of methyl acrylate was present in 1 kg of acrylamide in the obtained aqueous acrylamide solution by comparison with the measured values obtained by similarly distilling a standard solution of methyl acrylate at a concentration of 50% acrylamide.

(Evaluation of polyacrylamide) Using the obtained acrylamide solution, polyacrylamide powder was prepared in the same manner as in Example 1 and its physical properties were measured. As a result, the solution viscosity was 45 mPa · s and the insoluble content was 0 g.

Comparative Example 2 (Catalyst Preparation and Reaction) A biocatalyst was prepared in the same manner as in Example 1, 3510 g of 0.2 g / L sodium acrylate aqueous solution was added, and reaction to acrylamide was carried out in the same manner as in Example 1. Then
When the acrylamide concentration reached 37%, the acrylonitrile feed was stopped, and then the acrylonitrile
The reaction was continued until it became 0.005% or less. The immobilized bacterial cell catalyst was separated from this solution with a wire mesh having an opening of 100 μm to obtain 5 kg of a reaction solution having an acrylamide concentration of 40%.

(Concentration) 4 kg of the obtained reaction solution was placed in a separable flask having an internal volume of 10 L, and the concentration of acrylamide was kept in a warm bath under 45 mmHg and while introducing 150 mL / min of air to prevent the polymerization of acrylamide. Was concentrated to 50%. As a result, about 3.2 kg of a transparent 50% acrylamide aqueous solution was obtained. The resulting aqueous acrylamide solution was completely odorless.

(Measurement of Methyl Acrylate Concentration) In order to measure the methyl acrylate concentration in this liquid, 1 kg of the obtained reaction liquid was measured in the same manner as in Example 2, but it was detected by liquid chromatography. Therefore, the concentration of methyl acrylate in the obtained aqueous acrylamide solution was considered to be 0.1 mg or less per 1 kg of acrylamide.

(Evaluation of polyacrylamide) Using the obtained acrylamide aqueous solution, polyacrylamide powder was prepared in the same manner as in Example 1 and its physical properties were measured. As a result, the solution viscosity was 45 mPa · s and the insoluble content was 0 g.

[0043]

EFFECT OF THE INVENTION It is possible to provide a high-quality acrylamide aqueous solution which has a low risk of being mistaken for water and has a slight odor and which can be a raw material for high-performance polyacrylamide.

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Claims (8)

[Claims] 1. An aqueous acrylamide solution which emits an ester odor and is distinguishable from water by its odor. 2. An acrylamide aqueous solution which emits an ester odor and is distinguishable from water by an odor, and the polymer obtained from the acrylamide aqueous solution has a viscosity equal to that of the acrylamide aqueous solution in which only acrylamide is dissolved in water. An aqueous acrylamide solution that is equivalent in viscosity to the polymer obtained from the aqueous solution. 3. An aqueous acrylamide solution containing methyl acrylate, which emits an ester odor and is distinguishable from water by its odor. 4. An acrylamide aqueous solution containing methyl acrylate, which emits an ester odor and is distinguishable from water by an odor, wherein the polymer obtained from the acrylamide aqueous solution has a viscosity of only acrylamide dissolved in water. An acrylamide aqueous solution having a viscosity equivalent to that of a polymer obtained from an acrylamide aqueous solution having the same concentration as the aqueous solution. 5. Methyl acrylate 1 kg of acrylamide
The acrylamide aqueous solution according to claim 3 or 4, containing 0.1 to 10 mg per gram. 6. Methyl acrylate 1 kg of acrylamide
The acrylamide aqueous solution according to claim 5, which comprises 0.1 to 5 mg per unit. 7. The aqueous acrylamide solution according to claim 1, which is produced by a biocatalyst having a nitrile hydratase activity. 8. The aqueous acrylamide solution according to claim 7, wherein the aqueous acrylamide solution is produced without evaporating and concentrating.