JP2008138089A - Manufacturing method of (meth)acrylamide polymer of high quality - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a (meth)acrylamide polymer of high quality in a short polymerization time, that is, at a high polymerization rate. <P>SOLUTION: The manufacturing method of the acrylamide polymer comprises homopolymerizing or copolymerizing (meth)acrylamide having a phosphorus concentration of at most 20 ppm, or copolymerizing (meth)acrylamide with at least one unsaturated monomer copolymerizable with (meth)acrylamide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a high-quality (meth) acrylamide polymer. More specifically, the present invention relates to a method for producing a high-quality (meth) acrylamide polymer at a high polymerization rate by setting the phosphorus concentration in (meth) acrylamide to a specific amount or less.

  Acrylamide polymers are widely used for paper strength enhancers, flocculants and the like. In recent years, as a method for producing (meth) acrylamide, which is a raw material for this (meth) acrylamide polymer, it has advantages such as mild reaction conditions and very few by-products. A method using a catalyst has attracted attention. In this method, (meth) acrylonitrile is hydrated and converted to (meth) acrylamide by the enzyme nitrile hydratase contained in the microorganism.

  However, it has been known that when impurities such as hydrocyanic acid and oxazole are contained in the raw material acrylonitrile, the activity of nitrile hydratase contained in the microbial catalyst is lowered. In addition, acrylamide produced from acrylonitrile containing the above impurities has poor quality, and when it is used as a monomer, a high-quality polymer having high water solubility and high molecular weight and excellent agglomeration performance can be obtained. It was also known not to.

  For this reason, for example, in Patent Document 1, acrylonitrile having a reduced hydrocyanic acid concentration is used to suppress the deactivation of nitrile hydratase, thereby improving the productivity of acrylamide. Here, as a method for reducing the concentration of hydrocyanic acid, a method using an ion exchange resin, a method of removing hydrocyanic acid as a metal complex, and a method of removing hydronitrile by adding hydrocyanic acid under alkaline conditions are disclosed.

In Patent Document 2, an attempt is made to obtain a high-quality acrylamide polymer using acrylonitrile having a reduced oxazole concentration as well as hydrocyanic acid as a raw material. As a method for reducing the oxazole concentration, a method using an ion exchange resin and a method using purified distillation are disclosed.
Japanese Patent Laid-Open No. 11-123098 International Publication No. 2004/004847 Pamphlet

However, merely reducing the amounts of cyanic acid and oxazole contained in acrylonitrile has a problem that the polymerization rate when polymerizing acrylamide is lowered.
An object of the present invention is to provide a method for producing a high-quality (meth) acrylamide polymer at a high polymerization rate.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a high-quality (meth) acrylamide polymer at a high polymerization rate by setting the concentration of phosphorus in (meth) acrylamide to 20 ppm or less. I found out that

That is, the production method of the (meth) acrylamide polymer of the present invention is:
Homopolymerization or copolymerization of (meth) acrylamide having a phosphorus concentration of 20 ppm or less, or copolymerization of (meth) acrylamide with at least one unsaturated monomer copolymerizable with (meth) acrylamide; Features.

  The (meth) acrylamide is preferably (meth) acrylamide obtained by hydration reaction of (meth) acrylonitrile with a microbial catalyst containing nitrile hydratase in an aqueous medium.

  The (meth) acrylamide is preferably (meth) acrylamide in which the reaction liquid obtained by the hydration reaction is treated with an anion exchange resin to reduce the phosphorus concentration to 20 ppm or less.

  The (meth) acrylamide polymer according to the present invention is obtained by the method for producing the (meth) acrylamide polymer.

  According to the present invention, a high-quality (meth) acrylamide polymer can be produced at a high polymerization rate. In particular, in the case of an acrylamide polymer, a polymer having excellent water solubility and high molecular weight and excellent aggregation performance can be obtained at a high polymerization rate.

Hereinafter, the present invention will be described in detail.
In the method for producing a (meth) acrylamide polymer according to the present invention, (meth) acrylamide having a phosphorus concentration of 20 ppm or less is used. This (meth) acrylamide may be produced by hydration reaction of (meth) acrylonitrile with a copper-based catalyst, or (meth) acrylonitrile in an aqueous medium by a microbial catalyst containing nitrile hydratase. It may be produced by a hydration reaction. Below, the manufacturing method of (meth) acrylamide obtained by carrying out a hydration reaction with a microbial catalyst is demonstrated concretely.

<Aqueous medium>
The aqueous medium used in the present invention is water; or a buffer such as a phosphate, an inorganic salt such as a sulfate or carbonate, an alkali metal hydroxide, an amide compound or the like dissolved in an appropriate concentration. An aqueous solution is meant. Further, as will be described later, when the acrylonitrile and the microbial catalyst are added in the state of an aqueous solution, the aqueous medium includes these aqueous solutions.

The phosphorus concentration of (meth) acrylamide used in the present invention is 20 ppm or less, preferably 10 ppm or less, more preferably 2 ppm or less. In this specification, the concentration of phosphorus means (meta) as PO ₄ ³⁻ , HPO ₄ ²⁻ , H ₂ PO ₄ ^−, etc.
This is the total amount of phosphorus contained in acrylamide. The (meth) acrylamide having a phosphorus concentration of 20 ppm or less means that the amount of phosphorus contained in 1 kg of (meth) acrylamide is 20 mg or less.

In addition, the measuring method of the density | concentration of the phosphorus in the said (meth) acrylamide can be measured by IPC emission spectrometry.
When (meth) acrylamide whose phosphorus concentration is suppressed within the above range is used, a high-quality (meth) acrylamide polymer can be produced at a high polymerization rate. In the case of an acrylamide polymer, a polymer having excellent water solubility and high molecular weight and excellent aggregation performance can be obtained at a high polymerization rate.

The method for setting the concentration of phosphorus in the (meth) acrylamide to 20 ppm or less is not particularly limited. The phosphorus in the (meth) acrylamide is, for example, a phosphate used for adjusting the pH of the aqueous medium used for the hydration reaction, and the pH of the microorganism culture solution, as will be described later. Derived from the phosphate used. Therefore, the phosphate used for adjusting the pH of the aqueous medium may be adjusted and added so that phosphorus is not more than the above concentration, for example. Moreover, about the phosphate used for the said culture solution, after completion | finish of culture | cultivation of microorganisms, it can reduce by the method of wash | cleaning the culture solution containing microorganisms with a physiological saline, for example. Moreover, after culturing microorganisms, a culture solution containing microorganisms may be contacted with an ion exchange resin to remove phosphate ions. Examples of the ion exchange resin include anion exchange resins.

  Moreover, it is preferable to reduce the concentration of phosphorus in (meth) acrylamide contained in the reaction solution to 20 ppm or less by treating a reaction solution obtained by a hydration reaction described later with an anion exchange resin.

<(Meth) acrylonitrile>
In the present invention, commercially available (meth) acrylonitrile may be used as appropriate. (Meth) acrylonitrile may be previously prepared as a (meth) acrylonitrile aqueous solution and used in the hydration reaction.

<Microbial catalyst containing nitrile hydratase>
The microorganism containing nitrile hydratase used in the present invention is not particularly limited as long as it is a microorganism producing nitrile hydratase. Here, nitrile hydratase is an enzyme having the ability to hydrate (meth) acrylonitrile to produce (meth) acrylamide.

Examples of the microorganism include Nocardia, Corynebacterium, Bacillus, thermophilic Bacillus, Pseudomonas, Micrococcus, and Rhodochrous. ) Species represented by Rhodococcus genus, Acinetobacter genus, Xanthobacter genus, Streptomyces genus, Rhizobium genus, Klebsiella genus, Enterobacter genus ) Genus, Erwinia genus, Aeromonas genus, Citrobacter genus, Achromobacter genus, Agrobacterium genus, and Thermophila species Examples include microorganisms belonging to the genus Pseudonocardia. These microorganisms may be used alone or in combination of two or more.

In addition, the microorganism includes a transformant in which the nitrile hydratase gene cloned from the microorganism is expressed in an arbitrary host. In addition, as arbitrary hosts here, Escherichia coli (Escherichia coli); Bacillus genus bacteria, such as Bacillus subtilis; Other microbial strains, such as yeast and actinomycetes, etc. are mentioned. Specifically, as the above strain, MT-10822 (this strain is the 1st-3 East 1-chome, Tsukuba City, Ibaraki Prefecture on February 7, 1996, Institute of Biotechnology, Institute of Industrial Technology, Ministry of International Trade and Industry (currently : The National Institute of Advanced Industrial Science and Technology (AIST) and the Patent Biological Deposit Center)) under the deposit number FERM BP-5785 based on the Budapest Treaty concerning the international recognition of the deposit of microorganisms in the patent procedure. ).

  In addition, using recombinant DNA technology, one or more of the constituent amino acids of the enzyme is replaced, deleted, deleted or inserted with other amino acids to improve acrylamide resistance, acrylonitrile resistance and temperature resistance. A transformant expressing nitrile hydratase is also included in the microorganism referred to in the present invention.

The microbial catalyst containing nitrile hydratase used in the present invention includes, in addition to the microbial cells obtained by culturing the above-mentioned microorganisms, an extract of the microbial cells, a ground product of the microbial cells, Appropriate isolates obtained by separating and purifying the nitrile hydratase activity fraction of the extract or the ground product, the microbial cells, the extract of the cells, the ground product of the cells, the subsequent isolates, etc. Also included is a treated product of cells such as an immobilized product immobilized using a carrier. One of these may be used, two or more of them may be used simultaneously, or may be used alternately. Furthermore, the microbial catalyst containing the nitrile hydratase includes an aqueous solution containing at least one of them, a solution such as a buffer solution, and a suspension containing at least one of them. The use form of these microbial catalysts may be appropriately selected depending on the stability of nitrile hydratase, the production scale, and the like.

  What is necessary is just to prepare the above microorganisms by a well-known method. For example, after inoculating the microorganism in a liquid medium such as LB medium or M9 medium, an appropriate culture temperature (usually 20 ° C. to 50 ° C., but in the case of thermophilic bacteria, it may be 50 ° C. or higher) The microorganism is then separated from the culture medium by centrifugation and collected.

<Hydration reaction>
The production of (meth) acrylamide by the hydration reaction is carried out by a conventional method, and can be carried out, for example, as follows.

  In the present invention, the concentration of (meth) acrylonitrile in the aqueous medium is a concentration higher than the saturated concentration of (meth) acrylonitrile at the start of the reaction. The upper limit of the concentration is not particularly limited, but the supply of a large excess of (meth) acrylonitrile is necessary to complete the reaction with a large amount of catalyst, a reactor having an excessive volume, and heat removal. An excessive heat exchanger or the like is required, which increases the economic burden on the facilities. For this reason, as the supply concentration of (meth) acrylonitrile, when it is all converted to the corresponding (meth) acrylamide, the theoretical product solution concentration is in the range of 40 to 80% by weight in the case of acrylamide. More specifically, it is preferable to supply acrylonitrile in an amount of 0.4 to 1.5 parts by weight with respect to 1 part by weight of water. In the case of methacrylamide, it is preferable to supply such that the theoretical product concentration is in the range of 10 to 40% by weight. More specifically, methacrylonitrile is preferably added in an amount of 0.1% by weight with respect to 1 part by weight of water. It is preferable to supply in the range of 08 to 0.5 parts by weight.

  The amount of the microbial catalyst used may be appropriately determined depending on the reaction conditions, the type of catalyst, and the form thereof, but in terms of the dry cell weight, it is usually 10 to 50000 ppm by weight, preferably 50 to 30000 wt. ppm.

  The reaction time in the hydration reaction is usually in the range of 1 to 80 hours, preferably in the range of 2 to 40 hours, although it depends on conditions such as the amount of catalyst used and the temperature. The hydration reaction is usually performed at normal pressure, but may be performed under pressure in order to increase the solubility of the nitrile compound in the aqueous medium. The reaction temperature is not particularly limited as long as it is at or above the freezing point of the aqueous medium, but it is usually in the range of 0 to 50 ° C, preferably in the range of 10 to 40 ° C. The pH of the aqueous medium in the hydration reaction is not particularly limited as long as the activity of the nitrile hydratase is maintained, but is preferably in the range of pH 6 to 10, more preferably in the range of pH 7 to 9. It is desirable that The hydration reaction may be performed in a slurry state where the product is crystallized in the reaction solution, or may be performed either batchwise or continuously.

In addition, you may process manufactured (meth) acrylamide by methods, such as concentration, ion exchange, crystallization, activated carbon treatment, for example.
High-quality (meth) acrylamide is obtained by the production method as described above. That is, in the obtained (meth) acrylamide, the phosphorus concentration is reduced to 20 ppm or less by appropriately using the above-described method for reducing the phosphorus concentration.

<Method for producing (meth) acrylamide polymer>
In the method for producing a (meth) acrylamide polymer of the present invention, the (meth) acrylamide obtained as described above can be homopolymerized or copolymerized, or the (meth) acrylamide can be copolymerized with (meth) acrylamide. Copolymerized with at least one unsaturated monomer.

As an unsaturated monomer copolymerizable with (meth) acrylamide,
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and their salts;
Vinyl sulfonic acid, styrene sulfonic acid, acrylamidomethylpropane sulfonic acid and their salts;
Alkylaminoalkyl esters of (meth) acrylic acid such as N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate acrylic acid, or their quaternary ammonium derivatives;
N—N-dialkylaminoalkyl (meth) acrylamides such as N—N-dimethylaminopropyl methacrylamide, N, N-dimethylaminopropyl acrylamide, or quaternary ammonium derivatives thereof;
Hydrophilic acrylamides such as acetone acrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N, N-diethylacrylamide, N-propylacrylamide;
N-acryloylpyrrolidine, N-acryloylpiperidine, N-acryloylmorpholine;
Hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate;
Methoxypolyethylene glycol (meth) acrylate, N-vinyl-2-pyrrolidone; N, N-di-n-propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide, Nn-hexylmethacrylamide, N -N-alkyl (meth) acrylamide derivatives such as n-octylacrylamide, Nn-octylmethacrylamide, N-tert-octylacrylamide, N-dodecylacrylamide, Nn-dodecylmethacrylamide;
N, N-diglycidylacrylamide, N, N-diglycidylmethacrylamide, N- (4-glycidoxybutyl) acrylamide, N- (4-glycidoxybutyl) methacrylamide, N- (5-glycidoxy N- (ω-glycidoxyalkyl) (meth) acrylamide derivatives such as pentyl) acrylamide, N- (6-glycidoxyhexyl) acrylamide;
(Meth) acrylate derivatives such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate;
Examples include olefins such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene, and butene, styrene, α-methylstyrene, butadiene, and isoprene.

These monomers may be used alone or in combination of two or more. Further, acrylamide and methacrylamide may be copolymerized with these other unsaturated monomers.
There is no particular limitation on the mixing ratio in the case of copolymerizing (meth) acrylamide and these unsaturated monomers, but usually the unsaturated monomer is 100 mol or less with respect to 100 mol of (meth) acrylamide. , Preferably it is 50 mol or less.

The method for producing the (meth) acrylamide polymer is not particularly limited and is performed by a known method such as aqueous solution polymerization or emulsion polymerization, and aqueous solution polymerization using a radical polymerization initiator is preferably used. In the case of aqueous solution polymerization, it is usually preferable that the total concentration of (meth) acrylamide and the unsaturated monomer added as necessary is 5 to 90% by weight.

As the polymerization initiator, for example, a radical polymerization initiator is used, and specifically,
Peroxides such as potassium persulfate, ammonium persulfate, hydrogen peroxide, benzoyl peroxide; azobisisobutyronitrile, 2,2′-azobis (4-amidinopropane) dihydrochloride, 4
Azo free radical initiator such as 4,4′-azobis (sodium 4-cyanovalerate); a so-called combination of the above peroxide and a reducing agent such as sodium bisulfite, triethanolamine, ferrous ammonium sulfate, etc. Redox-based catalysts are exemplified.

The above polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator is usually in the range of 0.001 to 5% by weight based on the total weight of the monomers.
In the case of a single polymerization initiator, the polymerization temperature is usually in the range of −10 to 120 ° C., and in the case of the redox polymerization initiator, the polymerization start temperature is usually in the range of 0 to 90 ° C. Further, the polymerization temperature does not always need to be maintained at a constant temperature, and may be appropriately changed as the polymerization proceeds. Usually, however, the polymerization temperature tends to increase as the polymerization proceeds. Therefore, it may be cooled as necessary.

The atmosphere during the polymerization is not particularly limited, but from the viewpoint of rapidly proceeding the polymerization, it is preferable to carry out the polymerization in an inert gas atmosphere such as nitrogen gas.
The polymerization time is not particularly limited, but is usually in the range of 1 to 20 hours.

  The pH of the aqueous solution at the time of polymerization is not particularly limited, but polymerization may be carried out by adjusting the pH if necessary. Examples of pH adjusters that can be used in this case include alkalis such as sodium hydroxide, potassium hydroxide and ammonia; mineral acids such as sulfuric acid and hydrochloric acid; organic acids such as formic acid and acetic acid.

The molecular weight of the polymer obtained by the present invention is not particularly limited, but is usually in the range of 100,000 to 50 million, and preferably in the range of 500,000 to 30 million.
In order to obtain a polymer having a high molecular weight of 10 million or more, particularly about 15 million, the total concentration of acrylamide and other monomers, the type of polymerization initiator to be used, its concentration, the reaction temperature, etc. may be appropriately adjusted. Good. Moreover, as a method for making unreacted acrylamide into 0.2 weight% or less, for example, the method of making 2 or more types of polymerization initiators act in a different temperature range etc. are mentioned.

  In this way, a high-quality (meth) acrylamide polymer can be produced at a high polymerization rate. In the case of an acrylamide polymer, it has excellent water solubility and can have a high molecular weight, and is suitably used as a paper strength enhancer, a flocculant and the like.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
[Example]
[Preparation of microbial catalyst containing nitrile hydratase]
In accordance with the method described in Example 1 of JP-A-2001-340091, no. Three clone cells were obtained and similarly cultured by the method of Example 1 to obtain wet cells containing nitrolyl hydratase.

[Production of acrylamide]
In order to obtain a final product having an acrylamide concentration in the aqueous solution of 50% by weight, the reaction was performed under the following conditions.

  A 1 L glass flask equipped with a stirrer was prepared as the first reactor, and a Teflon (registered trademark) tube 20 m having an inner diameter of 5 mm was prepared as the second reactor. The first reactor was charged with 400 g of water in advance.

  The wet cells obtained by the above culture method were suspended in pure water. The suspension was continuously fed at a rate of 11 g / h while stirring in the first reactor. Acrylonitrile was continuously fed at a rate of 32 g / h, and pure water was continuously fed at a rate of 37 g / h. Furthermore, 0.01% -phosphate buffer aqueous solution was fed so that reaction pH might be 7.5-8.5. These feeds were fed from each storage tank in a single line and did not come into contact with other feeds until fed into the reactor. Further, in order to keep the liquid level of the first reactor constant, the reaction solution is continuously withdrawn from the first reactor at a rate of 80 g / h, continuously fed to the second reactor, The reaction was allowed to proceed further in the reactor. The addition amount of the wet cells was adjusted so that the acrylonitrile conversion rate in the first reactor was 90%.

Both the first reactor and the second reactor were immersed in a water bath at a temperature of 10 to 20 ° C., and the temperature was controlled so that the liquid temperature inside each reactor was 15 ° C.
On the second day from the start of operation, the reaction solution (reaction solution (I)) of each reactor was sampled and analyzed under the following HPLC conditions. Conversion to acrylamide at the outlet of the first reactor The ratio was 90%, the acrylonitrile concentration at the outlet of the second reactor was below the detection limit (100 ppm by weight or less), and the acrylamide concentration was 53.5% by weight.

Here, the analysis conditions were as follows.
Acrylamide analysis conditions:
High-performance liquid chromatograph: LC-10A system (manufactured by Shimadzu Corporation)
(UV detector wavelength 250nm, column temperature 40 ℃)
Separation column: SCR-101H (manufactured by Shimadzu Corporation)
Eluent: 0.05% (volume basis)-phosphoric acid aqueous solution acrylonitrile Analysis conditions:
High-performance liquid chromatograph: LC-10A system (manufactured by Shimadzu Corporation)
(UV detector wavelength 200nm, column temperature 40 ℃)
Separation column: Wakosil-II 5C18HG (Wako Pure Chemical Industries)
Eluent: 7% (volume basis)-acetonitrile,
0.1 mM acetic acid, 0.2 mM sodium acetate
Aqueous solution contained at each concentration The acrylamide concentration was determined as follows. A commercially available acrylamide was dissolved in pure water to prepare an acrylamide aqueous solution with a known concentration, and a calibration curve for acrylamide concentration analysis in HPLC was prepared. Using this, the area value at the time of HPLC analysis of the test solution was converted to acrylamide concentration (absolute calibration curve method). The amount of the reaction solution used for HPLC measurement was 5 μL. In addition, since there was almost no influence of the density of each reaction liquid, the acrylamide density | concentration (weight%) was obtained in this way.

The reaction was continued for about 4 days after the analysis was performed on the second day. In about 4 days, about 7500 g of a reaction solution (reaction solution (I)) was obtained. On the other hand, after adding 30 g of activated carbon (powdered activated carbon PM-SX manufactured by Mikura Kasei Co., Ltd.) and adding 160 g of 0.5 wt% -acrylic acid aqueous solution, the pH was adjusted to 5 with 1 M NaOH aqueous solution. . After stirring this at 25 degreeC for 5 hours, it filtered with the filter paper and removed activated carbon. Thereafter, in order to recover acrylamide adhering to the activated carbon, the activated carbon is washed with 300 g of pure water, mixed with the previous activated carbon treatment solution, neutralized with 1M NaOH aqueous solution, pH is 7, and about 7900 g of product ( Reaction liquid (II)) was obtained. The final acrylamide concentration in the product after the activated carbon treatment (reaction solution (II)) was 50.6.
% By weight. In addition, when the density | concentration of phosphorus was measured by the ICP emission spectrometry, the density | concentration of phosphorus with respect to acrylamide was 160 ppm.

  Furthermore, 200 mL of an anion exchange resin that was previously made into an OH type using a 1M-NaOH aqueous solution was charged into a glass column, and the reaction liquid (SV = 1 (1 / h) was added thereto at a rate of SV = 1 (1 / h). II) was passed through to remove impurities. That is, the concentration of phosphorus in (meth) acrylamide contained in the reaction solution (II) was reduced. Finally, neutralization was performed with 1M-sulfuric acid, and the pH was adjusted to 7 to obtain an aqueous acrylamide solution of about 50% by weight.

[Measurement results of phosphorus]
When the obtained acrylamide aqueous solution was measured by ICP emission spectrometry, the concentration of phosphorus relative to acrylamide in the acrylamide contained in the aqueous solution was 0.1 ppm or less.

[Example 1]
[Production of acrylamide polymer]
Water was added to the acrylamide aqueous solution obtained by the above method to obtain an acrylamide aqueous solution having a concentration of 20% by weight. 500 g of this 20 wt% acrylamide aqueous solution was placed in a 1 L polyethylene container, and while maintaining the temperature at 18 ° C., dissolved oxygen in the liquid was removed through nitrogen, and immediately placed in a heat insulating block made of polystyrene foam.

Then, 200 × 10 ⁻⁶ mpm (molar ratio to acrylamide) of 4,4′-azobis (sodium 4-cyanovalerate), 200 × 10 ⁻⁶ mpm dimethylaminopropionitrile, and 80 × 10 ⁻⁶ mpm Of ammonium persulfate were each dissolved in a small amount of water and quickly poured into a 1 L polyethylene container in this order. Nitrogen gas was previously passed through these reagents, and before and after injection, a small amount of nitrogen gas was also passed through the polyethylene container to prevent oxygen gas from being mixed.

  When the reagent was injected, after the induction period of several minutes, the temperature inside the polyethylene container was observed to rise, so the supply of nitrogen gas was stopped. When the polyethylene container was held in the heat insulation block for about 100 minutes, the temperature inside the polyethylene container reached about 70 ° C. Therefore, the polyethylene container was taken out from the heat insulation block and immersed in water at 97 ° C. for 2 hours to further proceed the polymerization reaction. Thereafter, it was immersed in cold water and cooled to stop the polymerization reaction.

  The water-containing gel of acrylamide polymer thus obtained was taken out from the polyethylene container, divided into small chunks and ground with a meat grinder. The ground gel containing acrylamide polymer was dried with hot air at 100 ° C. for 2 hours, and further pulverized with a high-speed rotary blade pulverizer to obtain a dry powdery acrylamide polymer.

  The obtained dry powdery acrylamide polymer was passed through a sieve to fractionate a 32-42 mesh polymer. The fractionated acrylamide polymer was evaluated by the acrylamide polymer test method described later. The evaluation results are shown in Table 1.

[Examples 2 and 3 and Comparative Example 1]
An acrylamide polymer was produced in the same manner as in Example 1 except that acrylamide having a concentration of phosphorus in acrylamide of 2, 20, and 40 ppm was used. In addition, the acrylamide which is 2 ppm adds potassium dihydrogen phosphate so that it may become 8.7 ppm with respect to the acrylamide (pure part) obtained by said "manufacture of acrylamide", and also 0.01% -sodium hydroxide Obtained by adjusting the pH to 7 with an aqueous solution. Acrylamide at 20 and 40 ppm was prepared in the same manner.

The evaluation results are shown in Table 1.
[Testing method for acrylamide polymer]
The polymerization rate during the production of the polymer sample was evaluated by the time required to reach the maximum temperature.

In addition, the water solubility and standard viscosity of the obtained polymer sample were evaluated by the following methods.
Water solubility: Water solubility is 600 mL of water in a 1 L beaker, and 0.66 g of polymer sample (0.6 g of polyacrylamide pure content) is added while stirring at 25 ° C. with a stirring blade of a predetermined shape, and 2 at 400 rpm. Stirring was performed for a period of time, and the resulting solution was filtered through a 150-mesh wire mesh. In other words, ◎ is completely dissolved, ◯ is close to completely dissolved, there is an insoluble matter, △ is what can be filtered, △, slow passage of the filtrate, practically impossible to filter the insoluble matter Was marked with x.

  Standard viscosity: The filtrate obtained by the above water solubility test is a polymer aqueous solution having a concentration of 0.1% by weight. To this, sodium chloride corresponding to a concentration of 1M is added, and a BL type viscometer is used with a BL adapter at 25 ° C. The viscosity was measured at a rotor rotational speed of 60 rpm (standard viscosity). The standard viscosity obtained by such a method is conventionally used as a value correlated with the molecular weight.

Claims (4)

  (Meth) acrylamide having a phosphorus concentration of 20 ppm or less is homopolymerized or copolymerized, or the (meth) acrylamide is copolymerized with at least one unsaturated monomer copolymerizable with (meth) acrylamide, A method for producing a (meth) acrylamide polymer.   The (meth) acrylamide system according to claim 1, wherein the (meth) acrylamide is (meth) acrylamide obtained by hydrating a (meth) acrylonitrile with a microbial catalyst containing nitrile hydratase in an aqueous medium. A method for producing a polymer.   The said (meth) acrylamide is a (meth) acrylamide by which the reaction liquid obtained by the said hydration reaction was processed with the anion exchange resin, and the density | concentration of phosphorus was reduced to 20 ppm or less. A method for producing a (meth) acrylamide polymer.   A (meth) acrylamide polymer obtained by the method for producing the (meth) acrylamide polymer according to claim 1.