JP2006169414A - Method for producing high-molecular weight water-soluble polymer dispersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a dispersion of high-molecular weight acrylamide-based polymer. <P>SOLUTION: When producing the dispersion by polymerizing a monomer containing acrylamide by a disperse polymerization method in an aqueous solution of a salt, an acrylamide produced by hydrating acrylonitrile by catalytic action of nitrile hydratase is used as the acrylamide to produce the high-molecular weight water-soluble polymer dispersion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for producing a high molecular weight acrylamide polymer dispersion by a dispersion polymerization method.

Technical background

Acrylamide polymer dispersions are faster to dissolve and easier to handle than powdered polymers, so they can be used in various wastewater treatment, waste mud treatment, papermaking, civil engineering, etc. as flocculants and thickeners. Its applications are expanding, and high molecular weight polymers are required especially for flocculant and papermaking applications.

Trying to obtain a high molecular weight acrylamide polymer with an acrylamide content of 50 mol% or more of the total monomer by the dispersion polymerization method increases the monomer concentration or reduces the amount of initiator. Is common. However, in this case, there is a drawback that partial crosslinking occurs during the polymerization and the aqueous solution of the produced dispersion becomes cloudy. When a chain transfer agent is added to overcome this, white turbidity can be prevented, but the molecular weight decreases.

JP-A-9-118704

An object of the present invention is to obtain a dispersion of a high molecular weight acrylamide polymer.

As a result of intensive studies to solve the above problems, the present inventors have found that a dispersion of a high molecular weight acrylamide polymer can be produced by using an acrylamide aqueous solution produced by an enzymatic method. The headline has led to the present invention.

That is, in the present invention, when a monomer containing acrylamide is polymerized by a dispersion polymerization method in an aqueous salt solution to produce a dispersion, the acrylamide is produced by hydrating acrylonitrile by the catalytic action of nitrile hydratase. The gist of the present invention is a method for producing a high-molecular-weight water-soluble polymer dispersion.

The dispersion composed of the high molecular weight water-soluble polymer of the present invention is obtained for the first time by using acrylamide produced by an enzymatic method, and is produced by a conventional catalytic hydration method using copper or a copper compound as a catalyst. It cannot be obtained by using an aqueous acrylamide product. The difference between the two is presumed to be due to the presence or absence of some impurities based on the difference in each acrylamide production method.

Acrylamide used in the present invention is produced by hydrating acrylonitrile by the catalytic action of nitrile hydratase. Nitrile hydratase is an enzyme that converts a nitrile compound into a corresponding amide compound, for example, the genus Bacillus, the genus Bacteridium, the genus Micrococcus, the genus Brevibacterium ( No. 62-21519), Corynebacterium genus, Nocardia genus (No. 56-17918), Pseudomonas genus (No. 59-37951), Rhodococcus genus , Microbacterium genus (Japanese Patent No. 4-4873), Rhodococcus genus (Japanese No. 4-40948), Rhodococcus rhodochrous species (Japanese No. 6-55148, SU 1731814) And those derived from microorganisms belonging to the genus Fusarium (JP-A 64-86889) and Agrobacterium (JP-A-5-103681, JP-A-6-14786)

Nitrile hydratase can be used as a culture solution of the above microorganism, resting cells or immobilized cells separated from the culture solution, or extracting nitrile hydratase-active enzyme from resting cells and immobilizing directly or on a carrier Any of these may be used.

The hydration reaction condition of acrylonitrile to acrylamide is not particularly limited as long as it conforms to the conditions of the enzymatic method in which the reaction is performed at normal temperature and normal pressure. Further, the acrylamide aqueous solution after the hydration reaction may be used as it is, or it may be used after increasing the acrylamide concentration by a concentration operation.

In the dispersion polymerization in the present invention, a monomer containing acrylamide is dissolved in a salt aqueous solution that dissolves the monomer but does not dissolve the produced polymer, in the presence of a dispersant composed of a polymer soluble in the salt aqueous solution. The polymer can be obtained in the state of being dispersed as fine polymer particles having a particle diameter of 100 μm or less.

A water-soluble polymer comprising a polymer fine particle dispersion dispersed in an aqueous salt solution can be produced by Japanese Patent Application Laid-Open No. Sho 62-15251. The manufacturing method will be specifically described as follows. An aqueous solution of a polyvalent anion salt such as ammonium sulfate is prepared, a monomer containing acrylamide is added, and an ionic polymer such as an acryloyloxyethyltrimethylammonium chloride polymer as a dispersant is allowed to coexist before polymerization. The pH at this time is set to 2-6. After the mixture is uniformly dissolved, the polymerization can be started by removing oxygen in the reaction system by nitrogen substitution and adding a radical polymerizable initiator to produce a polymer. In addition, the presence of a chain transfer agent, a crosslinking agent or the like before the start of polymerization is the same as other polymerization methods. Moreover, when polyhydric alcohols such as glycerin and polyethylene glycol coexist, the precipitation state may be further improved.

The monomer composition in the aqueous phase may be acrylamide alone or any combination of vinyl monomers copolymerizable with acrylamide, but the higher the proportion of acrylamide, the more remarkable the effect of the present invention. Yes, a high molecular weight water-soluble polymer dispersion can be obtained. That is, the proportion of acrylamide is usually 50 mol% or more, and the effect of the present invention is more apparent when it is 60 mol% or more.

Water-soluble vinyl monomers that can be copolymerized with acrylamide include nonionic monomers such as methacrylamide, anionic monomers such as 2-acrylamido-2-methylpropanesulfonic acid (salt), and acrylic acid (salt). ) And other cationic monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dimethylaminohydroxypropyl (meth) acrylate, dimethylaminoethylacrylamide, and methacryloyloxy Examples thereof include quaternary ammonium salts of the above cationic monomers such as ethyltrimethylammonium chloride, and water-soluble monomers such as vinylpyrrolidone. In addition, poorly water-soluble or hydrophobic monomers such as acrylonitrile, methyl methacrylate and styrene can be used as long as the water solubility of the resulting polymer is not impaired.

The molecular weight of the water-soluble polymer of the present invention can produce a polymer having an arbitrary molecular weight, but the higher the molecular weight, the more the effects of the present invention can be exhibited. That is, it is about 7 million to 20 million, preferably 9 million to 20 million. If it is less than 7 million, acrylamide by the conventional catalytic hydration method is sufficient, and the effect of the present invention is hardly exerted. However, it is difficult to produce a polymer of 20 million or more by mixing a chain transfer agent, temperature control, and other impurities. It becomes difficult to manufacture with other elements.

The dispersant made of a polymer used at the time of polymerization can be either ionic or nonionic, but is preferably ionic. First, examples of the cationic polymer include (meth) acryloyloxyethyltrimethylammonium chloride and dimethyldiallylammonium chloride, which are cationic monomers. These cationic monomers and nonionic monomers These copolymers can also be used. Examples of nonionic monomers include acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, acrylonitrile, diacetone acrylamide, 2-hydroxyethyl (meth) acrylate A copolymer with acrylamide is preferred.

On the other hand, as the anionic dispersant, (co) polymers of anionic monomers such as acrylamide 2-methylpropanesulfonic acid (salt) and styrenesulfonic acid (salt) can also be used. Copolymers of these anionic monomers and carboxyl group-containing monomers such as acrylic acid, methacrylic acid and itaconic acid can also be used. Furthermore, acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, acrylonitrile, diacetone acrylamide, 2-hydroxyethyl (meth) acrylate, which are nonionic monomers A copolymer with acrylamide, and a partially amidated product of maleic anhydride / butene copolymer can also be used, but a copolymer with acrylamide is preferred.

Nonionic polymers include amide groups and some hydrophobic groups such as polyvinylpyrrolidone, acrylamide / polyvinylcaprolactam copolymers, acrylamide / styrene copolymers or fully amidated products of maleic anhydride / butene copolymers. A water-soluble polymer is effective.

The molecular weight of these cationic or anionic polymer dispersants is 5,000 to 2,000,000, preferably 50,000 to 1,000,000. The molecular weight of the nonionic polymer dispersant is 1,000 to 100,000, preferably 1,000 to 50,000. The amount of these nonionic or ionic polymer dispersants added to the monomer is 1/100 to 2/10, preferably 2/100 to 1/10, with respect to the monomer.

Salts suitable for the present invention are divalent anion salts such as sulfates, and ammonium ions, sodium ions, magnesium ions, aluminum ions, etc. are selected as counter cations. Specific examples of the salt include ammonium sulfate, ammonium hydrogen sulfate, sodium sulfate, sodium hydrogen sulfate, magnesium sulfate, magnesium hydrogen sulfate, aluminum sulfate, and aluminum hydrogen sulfate. In particular, ammonium sulfate and sodium sulfate are most preferable as the salt applied to the present invention. In order for these divalent anion salts to have the above properties, the salt concentration is preferably selected in the range of 15% by weight or more to the saturation concentration. Monovalent anion salts such as sodium chloride and ammonium chloride can also be used in combination with the divalent anion salt.

The polymerization conditions are usually appropriately determined according to the monomer used and the copolymerization mol%, and the temperature is in the range of 0 to 100 ° C. For the initiation of polymerization, a radical polymerization initiator is used. These initiators may be either oil-soluble or water-soluble, and can be polymerized by any of azo, peroxide, and redox systems. Examples of oil-soluble azo initiators are 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2-methylpropionate), 4,4-azobis (4-methoxy-2,4dimethyl) valeronitrile and the like are mentioned and dissolved in a water-miscible solvent and added.

Examples of water-soluble azo initiators include 2,2′-azobis (amidinopropane) dichloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] And dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), and the like. Examples of redox systems include a combination of ammonium peroxodisulfate and sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine, and the like. Further examples of peroxides include ammonium or potassium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butylperoxy 2-ethylhexanoate, and the like. I can give you. Most preferred among these initiators are 2,2′-azobis (amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazoline), which is a water-soluble azo initiator. -2-yl) propane] dihydrochloride.

The high molecular weight water-soluble polymer dispersion of the present invention is used for pulp sludge dewatering in the paper industry, yield improver in the papermaking process, other wastewater treatment in the food industry, metal and petroleum refining, and gravel washing wastewater related to building materials. It can also be applied to mixed sludge including organic sludge and agglomerated sludge generated in general industrial wastewater treatment. As a particularly effective object, it exhibits an excellent effect in dewatering sewage, digested sludge from human waste, or excess sludge from food industry wastewater. The amount added varies depending on the type of waste water, the concentration of the suspension, etc., but is about 0.1 to 1000 ppm with respect to the liquid amount. Moreover, with respect to sludge, it is 0.1 to 3 weight% with respect to sludge.

(Examples) Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

Used acrylamide sample [enzymatic method 50% acrylamide aqueous solution]. Comparative acrylamide sample [50% acrylamide aqueous solution by contact hydration (Mitsubishi Chemical Corporation)].

In a four-necked 500 ml separable flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube, deionized water: 131.7 g, 60% acrylic acid: 50.0 g, enzymatic method acrylamide 50% aqueous solution 140.3 g In addition, 15 mol% of the anionic monomer was neutralized with 8.3 g of 30 wt% sodium hydroxide. Further, 135.4 g of ammonium sulfate and 25.0 g of acrylamide 2-methylpropanesulfonic acid polymer (molecular weight: 200,000, 20 equivalent% neutralized product) in a 20% by mass aqueous solution (5.0% by mass of monomer) were added. did. Thereafter, nitrogen is introduced from the nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. using a constant temperature water bath. 30 minutes after the introduction of nitrogen, 2.5 g (0.2% by mass, 40 ppm) of 0.2% by mass ammonium peroxodisulfate and 0.2% by mass aqueous solution of ammonium hydrogen sulfite were added in this order to initiate the polymerization. Two hours after the addition of the initiator, the viscosity of the reaction liquid slightly increased but did not increase any more, and polymer fine particles began to precipitate for removal, and the viscosity decreased. After 8 hours from the start of polymerization, the same amount of each initiator was added, and the polymerization was continued for 15 hours to complete the reaction. Let this prototype be prototype-1. The molar ratio of acrylic acid / acrylamide in trial production-1 was 30/70, and the viscosity was 610 mPa · s. Microscopic observation revealed that the particles had a particle size of 5 μm or less. Moreover, the weight average molecular weight was measured with the molecular weight measuring device (DLS-7000 by Otsuka Electronics) by a static light scattering method. The results are shown in Table 1.

Acryloyloxyethyltrimethylammonium chloride in a 500 mL four-necked flask equipped with a thermometer, a stirrer, a nitrogen introduction tube, a monomer supply tube connected to a peristaltic pump (SMP-21 type, manufactured by Tokyo Rika Kikai) and a condenser (Hereinafter abbreviated as DMQ) 72.6 g of 80 wt% aqueous solution, 10.3 g of 60 wt% aqueous solution of acrylic acid (hereinafter abbreviated as AAC), 68.0 g of 50% aqueous solution of enzymatic acrylamide, 186.1 g of ion-exchanged water, ammonium sulfate 125.0 g and 30.0 g of acryloyloxyethyltrimethylammonium chloride homopolymer as a dispersant (20 wt% solution, viscosity 6450 mPa · s) were respectively squeezed to adjust the pH to 3.3. At this time, the mol% of each monomer is DMQ / AAC / AAM = 35/10/55. Next, the temperature in the reactor was kept at 30 ± 2 ° C., and after replacing with nitrogen for 30 minutes, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] as an initiator was used. Polymerization was initiated by adding 1.0 g of a 1% aqueous solution of dihydrochloride (0.01% monomer). When the internal temperature was kept at 30 ± 2 ° C. and the reaction was carried out for 7 hours from the start of polymerization, 0.01% of the initiator was added to the above monomer, and the reaction was further completed for 7 hours. The dispersion monomer obtained had a squeeze monomer concentration of 20%, a polymer particle size of 5 μm or less, and a dispersion viscosity of 750 mPa · s. This is designated as prototype-2. The results are shown in Table 1.

In a five-necked separable flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, 21.0 g of a dimethyldiallylammonium chloride polymer (30% aqueous solution, molecular weight of 200,000) (5. 08.4), ion exchange water 178.4 g, ammonium sulfate 115.0 g, enzymatic method acrylamide 50% aqueous solution 67.4 g and acryloyloxyethyltrimethylammonium chloride, 80% aqueous solution 115.0 g were completely dissolved. 10% of 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride as an initiator after maintaining the internal temperature at 33 to 35 ° C. and replacing with nitrogen for 30 minutes. 2.5 g of aqueous solution (0.04% monomer) was added to initiate polymerization. After 2.5 hours from the start, a slight increase in viscosity of the reaction product was observed, but it quickly settled and transferred to the dispersion. 8 hours after the start, 1.3 g of the initiator solution was added, and polymerization was further performed for 8 hours. The resulting dispersion has a squeeze monomer concentration of 25.0% and a polymer particle size of 5 μm or less. The results are shown in Table 1.

In the same manner as in Example 3, a copolymer dispersion of acrylamide / acryloyloxyethyltrimethylammonium chloride / acryloyloxyethylbenzyldimethylammonium chloride = 60/20/20, trial production-4 was synthesized. The results are shown in Table 1.

A four-necked 500 ml separable flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with 66.7 g of deionized water, 125.0 g of ammonium sulfate, 20.4 g of sodium sulfate, and 200.0 g of 50% aqueous solution of enzymatic acrylamide. I put in. Further, 27.5 g of acryloyloxyethyltrimethylammonium chloride polymer aqueous solution (20% aqueous solution, molecular weight of 1,200,000) (5.5% monomer) was added. Thereafter, nitrogen is introduced from the nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. using a constant temperature water bath. 30 minutes after the introduction of nitrogen, 0.1 g of 0.1 wt% ammonium peroxodisulfate and 0.1 wt% aqueous solution of ammonium hydrogen sulfite were added in this order, respectively, to initiate polymerization. After 3 hours from the start of polymerization, it was observed that the reaction liquid slightly thickened, but dispersed particles began to precipitate. After 8 hours from the start of polymerization, the same amount of each initiator was added, and the polymerization was continued for 15 hours to complete the reaction. This prototype was designated as prototype-5, and the dispersion viscosity was 520 mPa · s. Microscopic observation revealed that the particles had a particle size of 5 μm or less. The results are shown in Table 1.

(Comparative Examples 1 to 5) Deionized water: 131.7 g, 60% acrylic acid: 50.0 g, catalytic hydration in a 4-neck 500 ml separable flask equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube 140.3 g of a 50% aqueous solution of acrylamide was added, and 15 mol% of the anionic monomer was neutralized with 8.3 g of 30 wt% sodium hydroxide. Further, 135.4 g of ammonium sulfate and 25.0 g of acrylamide 2-methylpropanesulfonic acid polymer (molecular weight: 200,000, 20 equivalent% neutralized product) in a 20% by mass aqueous solution (5.0% by mass of monomer) were added. did. Thereafter, nitrogen is introduced from the nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. using a constant temperature water bath. 30 minutes after the introduction of nitrogen, 2.5 g (0.2% by mass, 40 ppm) of 0.2% by mass ammonium peroxodisulfate and 0.2% by mass aqueous solution of ammonium hydrogen sulfite were added in this order to initiate the polymerization. Two hours after the addition of the initiator, the viscosity of the reaction liquid slightly increased but did not increase any more, and polymer fine particles began to precipitate for removal, and the viscosity decreased. After 8 hours from the start of polymerization, the same amount of each initiator was added, and the polymerization was continued for 15 hours to complete the reaction. This prototype is referred to as comparison-1. The molar ratio of acrylic acid / acrylamide in Comparative-1 was 30/70, and the dispersion viscosity was 660 mPa · s. Microscopic observation revealed that the particles had a particle size of 5 μm or less. The results are shown in Table 1.

The water-soluble polymer dispersions of Comparative 2 to 5 were each polymerized by catalytic hydration acrylamide by the same operation as in Examples 2 to 5. The result is shown in 1.

ＡＡＣ：アクリル酸、ＡＡＭ：アクリルアミド、
ＤＭＱ：アクリロイルオキシエチルトリメチルアンモニウムクロリド
ＤＭＢＣ：アクリロイルオキシエチルベンジルジメチルアンモニウムクロリド、分散液粘度：ｍＰａ・ｓ、分子量：単位は万
アクリルアミド；Ｂ：酵素法、Ｒ：接触水和法
不溶解物量：分散液に対する不溶解物の含水重量 (Table 1)

AAC: acrylic acid, AAM: acrylamide,
DMQ: acryloyloxyethyltrimethylammonium chloride DMBC: acryloyloxyethylbenzyldimethylammonium chloride, dispersion viscosity: mPa · s, molecular weight: 10,000 acrylamide; B: enzymatic method, R: catalytic hydration method insoluble matter amount: dispersion Water content of insoluble matter for

As is apparent from the results, the molecular weight of the polymer constituting the water-soluble polymer dispersion using the enzymatic acrylamide is higher than that in the case of using the catalytic hydration method, and the amount of insoluble matter is also reduced.

Claims (3)

A monomer containing acrylamide is polymerized in an aqueous salt solution that dissolves the monomer but does not dissolve the produced polymer with stirring in the presence of a dispersant composed of a polymer soluble in the aqueous salt solution. In a dispersion polymerization method for obtaining fine polymer particles dispersed in an aqueous salt solution, the acrylamide is produced by hydrating acrylonitrile by the catalytic action of nitrile hydratase, A method for producing a combined dispersion. The method for producing a high molecular weight water-soluble polymer dispersion according to claim 1, wherein the acrylamide content is 50 mol% or more of the total monomers. The high molecular weight water-soluble polymer according to claim 1 or 2, wherein the high molecular weight water-soluble polymer containing acrylamide constituting the high molecular weight water-soluble polymer dispersion has a molecular weight of 7 to 20 million. A method for producing a combined dispersion.