JP2008156541A - Water-soluble polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-soluble polymer having low amidination degree and a method for producing the polymer. <P>SOLUTION: The water-soluble polymer containing 5-20 mol% amidine structure unit, 4-80 mol% acid amide group structure unit, 4-40 mol% cyano group structure unit and 0-76 mol% primary amine salt unit and having reduced viscosity of 0.1-10 dL/g measured at 25°C in the form of a 0.1 g/dL solution in 1 N sodium chloride solution is produced by the neutralization and heat-treatment of a Hofmann reaction product of a copolymer of (meth)acrylamide and (meth)acrylonitrile. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a water-soluble polymer, containing a specific repeating unit produced by neutralizing and heat-treating a copolymer of (meth) acrylamide and (meth) acrylonitrile after the Hofmann reaction, The present invention relates to a water-soluble polymer having a reduced viscosity value of 0.1 to 10 dl / g measured at 25 ° C. as a 0.1 g / dl solution in 1N saline.

Water-soluble polymers are used in various fields such as flocculants and paper chemicals. In particular, water-soluble polymers having cationic properties are important industrial chemicals with high aggregation performance. Conventionally known water-soluble polymers having cationic properties include dialkylaminoalkyl (meth) acrylate metal salts and ammonium salt polymers, polyacrylamide Hoffmann decomposition products and Mannich reaction products. There is an amidine-based water-soluble polymer having a novel structure and performance (Patent Document 1). This polyamidine-based water-soluble polymer can be produced by hydrolysis and heat treatment of a copolymer of N-vinylformamide and (meth) acrylonitrile in an acidic atmosphere. N-vinylformamide, which is one of the raw materials of the copolymer, has a problem in that it requires many steps for production, resulting in high monomer costs. Also, it is difficult to produce a polyamidine polymer having a low degree of amidine formation by this method. The reason for this is that the N-vinylformamide structural unit in the copolymer is hydrolyzed in an acidic atmosphere, and the primary amino group thus produced reacts with the acrylonitrile structural unit to produce an amidine structural unit in a high temperature acidic atmosphere. During the treatment, the N-vinylformamide structural unit is hydrolyzed to increase the primary amino group, and as a result, it is difficult to produce a polyamidine polymer having a low degree of amidine formation.
JP-A-5-192513

An object of the present invention is to provide a polyamidine polymer having a low degree of amidine conversion among amidine-based water-soluble polymers and a method for producing the same.

As a result of repeated studies to solve the above-mentioned problems, the present inventor explained below that the copolymer of (meth) acrylamide and (meth) acrylonitrile was produced by neutralizing and heat-treating after the Hofmann reaction. It was discovered that a polyamidine polymer having a low degree of amidine can be produced by such a method. That is, the invention of claim 1 includes 5 to 20 mol% of a repeating unit represented by the following formula (1) and / or formula (2), and 4 to 80 mol% of a repeating unit represented by the following formula (3). Containing 4 to 40 mol% of a repeating unit represented by the following formula (4) and 0 to 76 mol% of a repeating unit represented by the following formula (5), and containing 0.1 g / dl of 1 N saline solution. The solution is a water-soluble polymer having a reduced viscosity value measured at 25 ° C. of 0.1 to 10 dl / g.
In the formula, R ¹ and R ² represent a hydrogen atom or a methyl group, and X ⁻ represents an anion.

The invention of claim 2 is characterized in that the copolymer of (meth) acrylamide and (meth) acrylonitrile comprises (meth) acrylamide 60 to 90 mol% and (meth) acrylonitrile 40 to 10 mol%. Item 11. A water-soluble polymer according to Item 1.

The invention according to claim 3 is the water-soluble polymer according to claim 1, wherein the acid to be neutralized is hydrochloric acid.

A fourth aspect of the present invention is the water-soluble polymer according to the first or third aspect, wherein the neutralization is performed in a pH range of 0.5 to 4.

Invention of Claim 5 is 5-20 mol% of repeating units represented by following formula (1) and / or formula (2), 4-80 mol% of repeating units represented by following formula (3), A solution containing 4 to 40 mol% of a repeating unit represented by the following formula (4) and 0 to 76 mol% of a repeating unit represented by the following formula (5), and containing 0.1 g / dl in 1N saline. As a water-soluble polymer having a reduced viscosity value measured at 25 ° C. of 0.1 to 10 dl / g, a copolymer of (meth) acrylamide and (meth) acrylonitrile is neutralized after the Hofmann reaction and heat-treated. A method for producing a water-soluble polymer.

In the formula, R ¹ and R ² represent a hydrogen atom or a methyl group, and X ⁻ represents an anion.

The invention according to claim 6 is the method for producing a water-soluble polymer according to claim 5, wherein the neutralization is carried out in the range of pH 0.5-4.

The water-soluble polymer of the present invention comprises 5-20 mol% amidine structural units, 4-80 mol% acid amide group structures, 4-40 mol% cyano group structural units, and 0-76 mol primary amine base structural units. A polyamidine-based polymer having a low degree of amidineization, characterized by having a reduced viscosity value measured at 25 ° C. of 0.1 to 10 dl / g as a 0.1 g / dl solution in 1N saline. Is a molecule. This water-soluble polymer can be produced by subjecting a copolymer of (meth) acrylamide and (meth) acrylonitrile to neutralization and heat treatment after the Hofmann reaction. Preferably, the copolymer of (meth) acrylamide and (meth) acrylonitrile comprises (meth) acrylamide 60 to 80 mol% and (meth) acrylonitrile 40 to 20 mol%. Further, the neutralizing acid is hydrochloric acid. This water-soluble polymer can be produced by neutralizing and heat-treating a copolymer of (meth) acrylamide and (meth) acrylonitrile after the Hofmann reaction. In the present invention, the acid to be neutralized is preferably hydrochloric acid. Furthermore, in the present invention, the neutralization is preferably carried out in the range of pH 0.5-4.

The water-soluble polymer of the present invention is characterized in that it is a polyamidine polymer having a low degree of amidineization, and a copolymer of (meth) acrylamide and (meth) acrylonitrile is neutralized and heat-treated after the Hofmann reaction. Can be manufactured.

First, the copolymer of (meth) acrylamide and (meth) acrylonitrile will be described. As a copolymerization ratio of (meth) acrylamide and (meth) acrylonitrile, acrylamide is 60 to 90 mol%, (meth) acrylonitrile is 10 to 40 mol%, preferably acrylamide is 60 to 80 mol%, and (meth) acrylonitrile is 20 to 20 mol%. 40 mol%. In addition, other copolymerizable monomers can be copolymerized as long as the polyamidine reaction is not affected. Furthermore, since the Hoffman reaction is carried out in a strongly alkaline region, the copolymer must be resistant to alkali hydrolysis. Examples of such monomers are ethylene, styrene, (meth) acrylic acid, itaconic acid or maleic acid. Therefore, the range of such a monomer is 0 to 10 mol%.

The copolymerization method before the Hoffman reaction can be synthesized by a known polymerization method such as an aqueous solution polymerization method, a water-in-oil emulsion polymerization method, a water-in-oil dispersion polymerization method, or a salt-water dispersion polymerization method. it can. Therefore, the polymerization concentration can be in the range of 5 to 60% by mass, preferably 20 to 50% by mass. Moreover, as reaction temperature, it can carry out in the range of 10-100 degreeC.

The radical polymerization initiator for initiating polymerization of the copolymer before the Hoffman reaction 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) and the like are 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 or potassium peroxodisulfate and sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine, and the like. Examples of peroxides include ammonium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, and t-butylperoxy 2-ethylhexanoate. Can do. Most preferred among these initiators are 2,2′-azobis (amidinopropane) dichloride, 2,2′-azobis [2- (5-methyl-2-imidazoline), which is a water-soluble azo initiator. -2-yl) propane] hydrochloride.

The weight average molecular weight of the polyacrylamide copolymer before the Hoffman reaction can be arbitrarily adjusted depending on the application, and is about 100,000 to 15 million, preferably 100,000 to 10 million. If there is no problem in manufacturing.

Next, the conditions for the Hoffman reaction will be described. Examples of hypohalous acid to be used include sodium hypochlorite, potassium hypochlorite, sodium hypobromite, potassium hypobromite, sodium hypoiodite, potassium hypoiodite and the like. Examples of the coexisting alkali include sodium hydroxide and potassium hydroxide. The addition amount of hypohalous acid is 10 mol% to 150 mol% with respect to the amide group, preferably 20 group% to 120 mol%. Further, the amount of alkali to be coexisted is 10 to 250 mol% with respect to the amide group. The reaction is carried out at 30 to 80 ° C., preferably 30 to 60 ° C. After the reaction, the solution pH is neutralized in the range of 5 to 7.5. If it is higher than 7.5, hydrolysis of the remaining acid amide group occurs, and the anionic group increases, which is not preferable. Further, formation of a lactam ring is not preferable even at a pH lower than 5.

The reaction temperature of the Hoffman reaction can be selected from the range of 0 to 50 ° C, but more preferably 0 to 30 ° C. Although the reaction time depends on the reaction temperature and the polymer concentration in the reaction solution, it cannot be said unconditionally. For example, when the polymer concentration is 10% by mass, the reaction time is within several tens of minutes at 5 ° C. and within several minutes at 20 ° C. It is enough. Furthermore, the higher the polymer concentration, the shorter the reaction time. Next, after performing the Hoffman reaction under the above-described conditions, it is desirable to stop the reaction in order to suppress the progress of the side reaction. However, when used immediately after the reaction, it may not be necessary to stop the reaction. As a method for stopping the reaction, methods such as (1) adding a reducing agent, (2) cooling, and (3) lowering the pH of the solution by adding an acid can be used alone or in combination. (1) is a method in which the remaining hypohalite or the like is deactivated by reaction with a reducing agent. Specific examples of the reducing agent used include sodium sulfite, sodium thiosulfate, ethyl malonate, thioglycerol, triethylamine and the like. The amount of the reducing agent to be used is 0.005 to 0.15 times mol, preferably 0.01 to 0.10 times mol, of the hypohalite used in the normal reaction. (2) is a method of suppressing the progress of the reaction by cooling, and examples of the method include cooling with a heat exchanger or diluting with cold water. The temperature at that time is usually 50 ° C. or lower, preferably 45 ° C. or lower, more preferably 40 ° C. or lower. (3) is a method of stopping the Hoffman reaction by lowering the pH of a reaction completion solution, which usually shows pH 12-13, using an acid, and at the same time suppressing the progress of hydrolysis. The pH at that time may be not more than neutral and may be in the range of pH 0.5 to 6, but is preferably pH 0.5 to 4 in consideration of the subsequent amidation reaction. Examples of the acid used for pH adjustment include mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, and organic acids such as formic acid, acetic acid and citric acid.

The primary amino group content in the polymer after the Hoffman reaction is 5 mol% to 80 mol%, preferably 10 mol% to 50 mol%. If it is less than 5 mol%, it is difficult to proceed with the amidation reaction. Further, if it is attempted to introduce a primary amino group higher than 50 mol%, the copolymerization ratio of (meth) acrylamide must be increased, and as a result, the copolymerization ratio of (meth) acrylonitrile is lowered.

After the Hoffmann reaction, the reaction solution is neutralized with an acid, and the temperature is 20 to 100 ° C.
Preferably, at 30 to 80 ° C., the amidination reaction can be carried out by keeping the reactant in the range of pH 0.5 to 6, preferably in the range of pH 0.5 to 4. The acid used is preferably a strong acid such as hydrochloric acid, nitric acid or sulfamic acid, and most preferably hydrochloric acid. As specific conditions, for example, 0.7 to 5.0 times, preferably 1.0 to 2.5 times equivalent of strong acid is added to the substituted amino group in the copolymer, and usually 20 to 100 ° C. The cationized polymer having amidine units can be obtained by heating at a temperature of preferably 50 to 80 ° C., usually for 0.5 to 20 hours. This is because the primary amino group, which is a side chain functional group, reacts with a cyano group to become an imino group and amidine. In general, the larger the equivalent ratio of strong acid to substituted amino group, and the higher the reaction temperature, the more the amidine formation proceeds. In addition, in the case of amidine formation, it is preferable that 10% by weight or more, preferably 20% by weight or more of water is usually present in the reaction system with respect to the copolymer used for the reaction.

Although the influence of the repeating unit (4) on the performance as a water-soluble polymer is not clear, it is considered that there is no adverse effect. Although the repeating unit (4) is present in 4 to 40 mol% in the water-soluble polymer, since nitrile is an inexpensive monomer, the presence of the repeating unit (4) lowers the production cost in the water-soluble polymer and reduces the cost. It is effective in improving the superiority of the performance against A suitable abundance ratio of the repeating unit (4) is 4 to 30 mol%, particularly 4 to 20 mol%.

In the water-soluble polymer according to the present invention, the molar ratio [(1) + (2) / (4)] of the repeating unit (4) to the amidine unit is generally in the range of 0.125-5. Preferably, this molar ratio should be in the range of 0.5-5. This is because the use of more amidine units expands as a water-soluble polymer. The repeating unit (5) is cationic and is considered to contribute to the performance as a water-soluble polymer as well as the amidine unit. The repeating unit (5) is present in the water-soluble polymer in an amount of 0 to 76 mol%, preferably 5 to 50 mol%. The repeating units (1), (2) and (5) are all derived from the repeating unit (4). Accordingly, it is generally preferred that as many repeating units (4) as possible are converted to repeating units (1), (2) or (5). In the flocculant according to the present invention, the molar ratio [(5) / (1) + (2)] of the repeating unit (5) to the amidine unit is generally in the range of 0 to 3.8. The action of the repeating unit (5) in the water-soluble polymer is unclear, but if the number of the repeating unit (5) is too large, the performance as the water-soluble polymer may be affected. Absent. Therefore, the molar ratio [(5) / (1) + (2)] of the repeating unit (5) to the amidine unit is preferably in the range of 0 to 2.0.

The water-soluble polymer according to the present invention may further contain other repeating units in addition to the aforementioned repeating units. However, the total of the aforementioned repeating units (1) to (5) should account for 90 mol% or more, preferably 95 mol% or more. Other repeating units that can be usually contained in the water-soluble polymer according to the present invention include the following (6) to (9).

(In the formula, R ¹ and R ² represent a hydrogen atom or a methyl group, and M ⁺ represents a cation.) The repeating unit (6) is formed by hydrolysis of the repeating unit (3) and the repeating unit (4). That is, when a copolymer of nitriles and (meth) acrylamide is heated in the presence of a strong acid and water to form an amidine structure, some of the cyano groups and acid amide groups in the copolymer are hydrolyzed. A carboxyl group of the repeating unit (6) is generated.

The effect of the repeating unit (6) (carboxyl group unit) on the performance of the water-soluble polymer cannot be concluded because it is considered to depend on the application, but it is estimated that there is no problem at a certain mol%. . Therefore, the ratio of the repeating unit (6) in the flocculant is usually in the range of 0 to 10 mol%, preferably 0 to 5 mol%.

It is presumed that the repeating units (7) and / or (8) (lactam units) are generated from the repeating units (3) and (5). The influence on the performance of the lactam unit water-soluble polymer is unknown, but the ratio is generally in the range of 0 to 5 mol%, particularly 0 to 2 mol%.

As described above, the reduced viscosity of the water-soluble polymer of the present invention is usually in the range of 0.1 to 10 dl / g, preferably 1 to 8 dl / g. This means that it can be used in various applications depending on the degree of amidineization and reduced viscosity. For example, it is used for coagulating and removing suspended substances therein from various wastewaters. This is particularly effective for organic sludge. For example, in an urban sewage treatment plant, primary settled sludge settled from sewage, surplus sludge settled from effluent from an activated sludge tank or a mixture thereof (this mixture is usually referred to as “mixed raw sludge”), Furthermore, when this flocculant is added to the digested sludge generated when the activated sludge is subjected to the anaerobic fermentation treatment, a strong floc is formed. When this floc is processed by a pressure dehydration device such as a belt press, screw press, filter press, or pressure dehydration device such as a centrifugal separator or a vacuum filter, dehydration can be performed at a remarkably large dehydration rate, and low moisture content can be achieved. Filter cake is obtained. Applications are also conceivable for various papermaking chemicals.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “%” means “% by mass” unless otherwise specified.

In a 500 ml four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a condenser tube, 60.0 g of a mixture of acrylonitrile and acrylamide containing 24 mol of demineralized water containing the molar fraction of acrylonitrile shown in Table 1 was added. I put it in. After raising the temperature to 30 ° C. with stirring in a nitrogen gas stream, 0.3 g of a 1% 2,2′-azobis-2-amidinopropane dihydrochloride aqueous solution was added. After stirring and maintaining at 30 ° C. for 4 hours, the temperature was raised to 50 ° C. and further maintained for 3 hours to obtain a suspension in which a polymer was precipitated in water. 20 g of water was added to the suspension, then 1.5 equivalents of concentrated hydrochloric acid was added to the formyl group in the polymer, and the mixture was kept at 85 ° C. for 4 hours with stirring to amidine the polymer. . The obtained polymer solution was added to acetone and precipitated, and this was vacuum-dried to obtain Trial-1 to Trial-6.

For Prototype-1 to Prototype-6, the composition and reduced viscosity were measured by the following methods. The results are shown in Table-1.

The composition of each raw material polymer before the amidine formation was calculated from the integrated value of the absorption peak corresponding to each monomer unit in the ¹³ C-NMR spectrum ( ¹³ C-magnetic resonance spectrum). The composition of the polymers A to E after amidine formation was calculated from the integrated value of the absorption peak corresponding to each repeating unit of the ¹³ C-NMR spectrum. The repeating units (1) and (2) were determined as the total amount without distinction. The repeating units (7) and (8) were also determined as the total amount without distinction.

In addition, since the absorption peaks of the repeating units (1) and (2), (3) and (7) and (8) are observed at very close positions in the vicinity of 170 to 185 ppm, each absorption is performed by the following method. The structure corresponding to the peak was assigned. That is, the mass balance was confirmed by elemental analysis of the polymer and measurement of water content, and also the IR spectrum was measured in addition to the ¹³ C-NMR spectrum of the polymer, and the polymer spectrum and amidine group, amide group and lactam This method employs a method for comparing and examining in detail a spectrum of a known compound having a group or the like.

For prototype-1 to prototype-6, a 0.1 g / dl solution in 1N saline was measured at 25 ° C. using an Ostwald viscometer.

After holding prototype-1 to prototype-6 in an oven at 120 ° C. for 8 hours, 0.4 g of each polymer was taken, 200 ml of water was added to each, and the mixture was stirred and mixed at room temperature for 2 hours. The solution was poured onto a rubber plate and the amount of insoluble matter was determined as follows. The results are shown in Table-1.
○: No insoluble matter △: 2-5 insoluble particles ×: 6 or more insoluble matters XX: Almost insoluble

(Comparative Example) In a 500 ml four-necked flask equipped with a stirrer, a nitrogen introducing tube, and a cooling tube, 60.0 g of a mixture of acrylonitrile and N-vinylformamide containing acrylonitrile having a molar fraction shown in Table 1 and 240.0 g of demineralized water was added. The temperature was raised to 30 ° C. with stirring in a nitrogen gas stream, and 0.3 g of a 10% 2,2′-azobis-2-amidinopropane dihydrochloride aqueous solution was added. After stirring and holding at 40 ° C. for 4 hours, the temperature was raised to 50 ° C. and further maintained for 3 hours to obtain a suspension in which the polymer was precipitated in water. 20 g of water was added to the suspension, and then 1.25 equivalents of concentrated hydrochloric acid with respect to the formyl group in the polymer was added and kept at 100 ° C. for 4 hours with stirring to amidinate the polymer. . The obtained polymer solution was added to acetone to cause precipitation, and this was vacuum dried to obtain Comparative-1 to Comparative-2. The results are shown in Table-1.

(Table 1)


AAM; acrylamide, AN; acrylonitrile, NVF; N-vinylformamide, 1 + 2; amidine, 3; acid amide, 4; nitrile group, 5; primary amino group, 6; carboxyl group, 7 + 8; lactam group, 9;
Reduced viscosity; dl / g,

In a 500 ml four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a condenser tube, 60.0 g of a mixture of acrylonitrile and acrylamide containing 24 mol of demineralized water containing the molar fraction of acrylonitrile shown in Table 1 was added. I put it in. After raising the temperature to 30 ° C. with stirring in a nitrogen gas stream, 0.3 g of a 1% 2,2′-azobis-2-amidinopropane dihydrochloride aqueous solution was added. After stirring and maintaining at 30 ° C. for 4 hours, the temperature was raised to 50 ° C. and further maintained for 3 hours to obtain a suspension in which a polymer was precipitated in water. 20 g of water was added to the suspension, and the amidine was changed when the reaction pH was changed to 0.5-6 during amidine formation, and the amidine was changed when the reaction temperature was changed to 20-80 ° C. Tested for change in degree of conversion. After the reaction, the polymer solution obtained in the same manner as in Example 1 was added to acetone and precipitated, and this was vacuum-dried to obtain Trial-7 to Trial-15. In addition, the composition and the reduced viscosity were measured for the prototype-7 to the prototype-15 by the following method. The results are shown in Table 2.

(Table 2)
AAM; acrylamide, AN; acrylonitrile, NVF; N-vinylformamide, 1 + 2; amidine, 3; acid amide, 4; nitrile group, 5; primary amino group, 6; carboxyl group, 7 + 8; lactam group, 9;
Reduced viscosity; dl / g,

Claims (6)

A repeating unit represented by the following formula (1) and / or formula (2) produced by neutralizing and heat-treating a copolymer of (meth) acrylamide and (meth) acrylonitrile after the Hofmann reaction is 5 to 5. 20 mol%, 4 to 80 mol% of a repeating unit represented by the following formula (3), 4 to 40 mol% of a repeating unit represented by the following formula (4), and a repeating unit represented by the following formula (5) Water-soluble, characterized in that the unit contains 0 to 76 mol% and the reduced viscosity value measured at 25 ° C. is 0.1 to 10 dl / g as a 0.1 g / dl solution in 1N saline. High molecular.


In the formula, R ¹ and R ² represent a hydrogen atom or a methyl group, and X ⁻ represents an anion. The water-soluble composition according to claim 1, wherein the copolymer of (meth) acrylamide and (meth) acrylonitrile comprises (meth) acrylamide 60 to 90 mol% and (meth) acrylonitrile 40 to 10 mol%. High molecular. The water-soluble polymer according to claim 1, wherein the acid to be neutralized is hydrochloric acid. The water-soluble polymer according to claim 1 or 3, wherein the neutralization is performed in the range of pH 0.5-4. 5 to 20 mol% of repeating units represented by the following formula (1) and / or formula (2), 4 to 80 mol% of repeating units represented by the following formula (3), and represented by the following formula (4) 4 to 40 mol% of the repeating unit and 0 to 76 mol% of the repeating unit represented by the following formula (5) were measured at 25 ° C. as a 0.1 g / dl solution in 1N saline. A water-soluble polymer having a reduced viscosity value of 0.1 to 10 dl / g is subjected to a Hoffman reaction with a copolymer of (meth) acrylamide and (meth) acrylonitrile, and then the reaction product is neutralized and heat-treated. A method for producing a water-soluble polymer.






















In the formula, R ¹ and R ² represent a hydrogen atom or a methyl group, and X ⁻ represents an anion. The method for producing a water-soluble polymer according to claim 5, wherein the neutralization is carried out in a range of pH 0.5-4.