DD202036A5 - METHOD FOR PRODUCING A CATIONIC POLYMER FLOCKING AGENT FROM ACRYLAMIDE TYPE - Google Patents

Abstract

The invention relates to a process for the preparation of a cationic polymeric flocculant of acrylamide type for use as a flocculant, for example as a dehydrating aid in the dehydration of organically active sludge, which is formed by wastewater treatment, treatment of excreta, etc. The aim of the invention is to prepare cationic acrylamide polymers with good solubility in water. According to the present invention, a polyacrylamide useful as a good water-soluble flocculant, particularly as a high molecular weight cationic polymeric flocculant, is formed by substantially freeing crude acrylamide from N-acryloyl-acrylamide, the crude acrylamide being obtained by catalytic hydration of acrylonitrile with water in the presence of a metallic copper catalyst at a pH in the range of 4 to 10 and subsequent polymerization of the acrylamide.

Description

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Process for the preparation of a polymeric flocculant

Anwendungsge bie t of the invention

The invention relates to an improved process for the preparation of a cationic polymeric flocculant of the acrylamide type.

Acrylamide polymers have many uses, for example, as papermaking or fiber-processing resins, as polymeric flocculants, and as oil-yielding additives because they have good aqueous solubility and high molecular weight For use as paper processing resins, relatively low molecular weight polymers of, for example, hundreds of thousands may be used, but polymers used as polymeric flocculants usually have a high molecular weight of so high as many millions or more Recently, acrylamide polymers having an extremely high molecular weight of more than 10 million have come into production,

Polymeric flocculants of acrylamide type become coarse in. nonionic polymeric flocculants obtained using acrylamide alone as monomers, anionic polymeric flocculants obtained by partial hydrolysis of the amide group of the nonionic acrylamide polymers or by copolymerization of acrylamide with an anionic monomer such as acrylic acid and cationic polymeric flocculants obtained by copolymerization of acrylamide with a cationic monomer such as methacryloyloxyethyltrimethylammonium chloride.

The nonionic and anionic polymeric flocculants

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The predominant use of the cationic polymeric flocculant is that used as a dehydrating aid in the dehydration of organically active sludge obtained by wastewater treatment, treatment. of excrement, treatment of waste water from the recycling of food waste et <2. is formed.

Characteristic of the named technical solutions

With the widespread practice of high level wastewater treatment and the widespread establishment of sewerage systems, the amount of organic active sludge accumulated increased annually and the amounts of acrylamide type polymeric flocculants used for the above purposes, especially cationic polymeric flocculants, increased greatly. Since an increase in the dehydration ratio of organically active C " sludge allows the amount of heavy oil used in the ashing of the sludge to be reduced and makes it easy to handle the sludge in its recovery, it has been desired to use higher cationic polymeric flocculants To develop efficiency.

Acrylamide has recently been produced as a major constituent of the raw material for acrylamide-type polymer flocculants relatively easily by catalytically hydrating acrylonitrile with water in the presence of a metallic copper catalyst in a neutral range of pH 4 to 10, especially 6 to 9, in place of the conventional sulfuric acid method Hydration of acrylonitrile at high acidity at a pH of 1 or less.

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According to the invention, it has been found that acrylamide, which is produced by the

catalytically obtained with good results as a raw material for nonionic or anionic acrylamide polymers not only for the preparation of relatively low molecular weight polymers useful as paper processing resins, but also for the preparation of nonionic or anionic polymeric flocculants With. extremely high molecular weights, and that as a raw material for cationic polymers, the above acrylamide can satisfactorily be used in the preparation of polymers having such low molecular weights as are suitable for use as paper processing resins, but that when the above acrylamide is used in the art the production of cationic polymeric flocculants with high molecular weights is used, the products have a very poor solubility in water and are swollen in extreme cases only with water and hardly dissolve at all. As a result, the present inventors have realized that this problem places a great deal of restriction on the production of high performance cationic polymeric flocculants.

The present inventors have intensively tried to fathom the cause of the adverse effects of the above aerylamide with respect to the preparation of cationic poly beer flocculants without any deleterious effect on the preparation of nonionic and anionic polymeric flocculants, and found, surprisingly, that present in the acrylamide Si-acryloyl-acrylamide is a substance causing such adverse effects.

In US Pat. No. 3,130,229, the formation of N-acryloyl-acrylamide during the hydration reaction of acrylonitrile with HiI-

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In this patent, however, the formation of N-acryloyl-acrylamide is merely hypothesized, not confirmed The presence of an acid and heat are considered essential for the formation of N-acryloylacrylamide Acrylamide-formed SF-acryloyl-aerylamide is structurally a difunctional crosslinkable impurity such as methylenebisacrylamide, and the present inventors believe that it may be one of the impurities that affect the water solubility of nonionic polymeric flocculants having a molecular weight of several millions or more to reduce"

In contrast, the formation of N-acryloyl-acrylamide was in a neutral range of pH 4 to 10, especially 6 to 9 », as in the catalytic hydration of acrylonitrile with water in the presence of a metallic copper catalyst as contemplated by the present invention ₃ unknown.

Objective of the invention

The object of the invention is to provide an improved process for the preparation of an acrylamide-type polymer flocculant having a high molecular weight and good solubility in water, in particular a cationic polymeric flocculant useful as a dehydrating aid.

Explanation of the essence of the invention

The object of the invention is to find and eliminate the constituents influencing the solubility of water.

This object is achieved according to the invention by a

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in which an aqueous solution of the crude acrylamide is substantially freed of N-acryloyl-acrylamide, the acrylamide being obtained by catalytic hydration of acrylonitrile with water in the presence of a metallic copper catalyst at a pH in the range 4 to 10 Temperature in the range of 50 to 150 ⁰ G and at a pressure of atmospheric pressure to an elevated pressure of up to about 10 kg / cm, and then the acrylamide is polymerized. The process can give acrylamide-type cationic polymeric flocculants which have high molecular weights and excellent solubility in water and which can be used as denydratation agents.

Figure 1 is a graph showing the effect of solution temperature on the water solubility of a cationic polymeric flocculant prepared using acrylamide as a starting material, purified by single crystallization, to which N-acryloyl-acrylamide had been added.

Figure 2 is a graph showing the effect of solution temperature on water solubility of a cationic polymeric flocculant prepared using acrylamide as the starting material, purified by crystallization to which methylenebicacrylamide _{9 has} been added as a typical crosslinkable compound.

In these graphs, the ordinate indicates in wt .-% to a wasserunlöslichen'Anteil of the flocculant and the abscissa the content in ppm of H-Äcryoyl-acrylamide, based on the weight of Acrylamide, "The numbers 1,2, 3 and ₉ 4 refer to a solution temperature of 20 ⁰ C, 50 ⁰ G, 6O ⁰ C and · 70 ⁰ O.

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The present inventors found that ϊΤ-acryloyl-acrylamide is contained as an impurity in an aqueous acrylamide solution obtained by catalytic hydration of acrylonitrile with water in the presence of a metallic copper catalyst, and carried out an attempt to add U-acryloyl-acrylamide completely by a recrystallization

r ~ - - _(tion method of purified acrylamide of was N-acryloyl-acrylamide-free, these results was added, and a comparative test was added at the methylenebisacrylamide to the purified acrylamide The products are given in Comparative Examples 1 and 2 show.. that Ίί-acryloylacrylamide, which is entirely different from ^y of a typical cross-linkable compound such as Methylenbigiacrylamid, has no adverse effect on the water solubility of the nonionic and anionic polymeric flocculant that, however, the same degree of polymer to adverse effects on the water solubility of cationic · Flocculants, such as methylenebisacrylamide, even if its content is extremely low, and it has also been found that

(^) As the examples below show, there is a very close relationship between the degree of water solubility of the acrylamide polymer and the content of N-acryloyl-acrylamide.

A comparison between Figures 1 and 2 shows that IT-Acryloy! Acrylamide and methylenebisacrylamide behave completely differently with respect to the solution temperature. This fact suggests that the mechanism of reduction of water solubility by N-acryloy! -Acrylamide is different from that of methylenebisacrylamide, a typical crosslinkable compound. ,

The present inventors chose acrylamides which have no problem whatsoever in

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ionic and anionic polymeric flocculants , among such acrylamides prepared by the catalytic hydration method and derived from various production processes, and prepared cationic polymeric flocculants from the selected acrylamides; Water solubility, they determined a relationship between the suspected content and the analytical content of I-acryloyl-acrylamide using Fig. 1. The results showed that these content values show a very good agreement and the content of N-acryloylacrylamide to a great extent the water solubility of cationic polymeric flocculants is impaired »

From the foregoing, it is believed that S-acryloyl-acrylamide does not adversely affect the water solubility of nonionic and anionic polymeric flocculants, but results in a reduction in the water solubility of cationic polymeric flocculants.

The present invention will be described in more detail below.

The aqueous crude acrylamide solution used in the present invention is obtained by catalytic hydration of acrylonitrile with water in the presence of a metallic copper catalyst at a pH in the range of 4 to 10, especially 6 to 9 ». Bs were various metallic copper catalysts for use the production of acrylamide recommended, and all these can be used in the present invention. They may contain z _e B, metallic copper or metallic copper.

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de be catalysts. Specific examples are given below

1. A combination of a copper ion and copper in the form of wire, powder, etc.

2. Reduced copper obtained by reduction of a copper compound such as copper oxide, copper hydroxide or copper salts with hydrogen, carbon monoxide, etc. at a high temperature of e.g. B. 100 to 400 ⁰ G,

3. Reduced copper obtained by reducing a copper compound such as copper oxide, copper hydroxide or liquid phase copper salts with a reducing agent such as hydrazine, an alkali or alkaline earth metal borohydride compound or formaldehyde.

4. Reduced copper obtained by treating a copper compound such as copper oxide, copper hydroxide or liquid phase copper salts with a metal having a larger ionization tendency than copper such as zinc, aluminum, iron or tin.

5. Raney copper obtained by leaching a Raney alloy consisting of copper and aluminum, zinc or magnesium _β

6. Metallic copper obtained by thermal decomposition of an organic copper compound such as copper formate or copper oxalate at a temperature of, for. B. 100 to 400 ⁰ G.

7. A thermal decomposition product of copper hydride.

These copper-containing catalysts may contain metals other than copper, such as chromium or molybdenum, which are normally used, as well as commonly used supports.

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The reaction between acrylonitrile and water in the presence of the above copper-containing catalyst is usually carried out in the liquid phase using. Water in almost any amount, preferably of at least 4 moles, based on acrylonitrile at a temperature of 50 to 150 ^° C., preferably 80 to 140 ^° C., under atmospheric pressure or an elevated pressure which does not cause boiling of the water and of acrylonitrile, for example, up to about 10 kg / cm, in a slurry or fixed bed catalyst according to a continuous or batch reaction method. The reaction is carried out while reacting with the reactants and copper-containing catalyst Avoiding oxygen or an oxygen-containing gas.

The reaction is carried out at a pH in the range of 4 to 10, in particular β to 9j. If the pH is below 4 ₉ , the reaction rate is low, and if the pH is above 10, lifting reactions such as hydrolysis of the obtained acrylamide or formation of the di-nitrilo compounds remarkably occur, and the yield of the desired product decreases. Therefore, pH values outside the specified range, he does not want _e

The resulting aqueous solution of the crude acrylamide is then usually subjected to a distillation process to remove unreacted acrylonitrile from the solution or concentrate of the solution, such that an aqueous acrylamide solution having a concentration of e.g. B ₀ about 30 to 50 percent by _e - / Ä obtained. The aqueous solution of the crude acrylamide, optionally concentrated as above, is then treated on an ion exchange resin to remove impurities normally present, such as copper ions or acrylic acid, which is a hydrolysis product.

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In the process of the present invention, the amount of N-acryloylacrylamide contained in the aqueous solution of the acrylamide can always be controlled with good accuracy depending on the desired acrylamide polymer to be produced. Available methods for the removal of H-Acryoy! Acrylamide from the aqueous solution of acrylamide include, for. B.

v ^{., i:} the physical adsorption by activated carbon or activated carbon, activated clay, etc .; the reactive adsorption by a compound containing primary and secondary amines such as polyamines, a weakly basic Anionsaus-. exchange resin containing primary and "secondary amino groups or a compound having a peptide bond such as a protein (eg," silk) or its disintegration product; decomposition by chemical reaction such as alkaline hydrolysis or oxidation; extraction with a solvent such as chloroform or carbon tetrachloride, and the sublimation normally used in the art, alternatively it is possible to add a compound.

r ~ \ which is capable of forming an adduct with ΪΓ-acryloyl-acrylamld, rendering the latter harmless. "

These methods can be used either individually or in combination of two or more. Although some of these methods are known as a method of purifying an aqueous solution of acrylamide obtained by the catalytic hydration method, the content of the acryloyl-acrylamide under the purifying conditions of the prior art can not be below that specified in the method of the present invention Amount to be cleaned. Since the H-acryloyl-acrylamide amount contained in the aqueous solution of the crude acrylamide differs depending on the reaction conditions, the purification conditions

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always be analyzed, quantified and controlled _{s to} adjust the content of e-acryloyl-acrylamide in the purified acrylamide to a value below that in the inventive method, as indicated specified value.

The present inventors have found that the amount of N-acryloylacrylamide in the aqueous solution of the crude acrylamide increases when the concentration of the acrylonitrile in the recycled. and the use of such conditions can easily lead to the formation of an aqueous acrylamide solution unsuitable for use as a raw material for cationic polymeric flocculants. The amount of H-acrylolyl acrylamide in the acrylamide. which is permissible for the preparation of cationic polymeric flocculants is not more than 10 ppm, preferably not more than 5 ρ, especially not more than 1 ppm. Accordingly, in the present invention the term "acrylamide, which is essentially derived from N -Acryloyl-acrylamide is free, "an acrylamide containing not more than 10 ppm H-Acryloylacrylamid.

The thus-purified aqueous acrylamide solution is then polymerized in a conventional manner to give acrylamide-type cationic polymeric flocculants.

In the preparation of the acrylamide polymers according to the invention, various known conventional polymerization initiators can be used, examples include azo compounds such as azobisdimethylvaleronitrile, azobis (sodium cyanovalerate), azobisisobutyronitrile and azobisaminopropane hydrochloride organic peroxides such as benzoyl peroxide, lauroyl peroxide and tertiary butyl hydroperoxide and inorganic peroxides such as Potassium persulfate, matrium perbromate, ammonium persulfate and hydrogen peroxide,

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Examples of suitable reducing agents are inorganic compounds such as ferrosulfate, ferrous chloride, sodium bisulfite, sodium metasulfite, sodium thiosulfate and nitrite salts and organic compounds such as dimethylaniline, 3-dimethylethylaminopropionitrile and phenylhydrazine,

For the preparation of a high molecular weight polymer by the process of the present invention, a mixture of acrylamide and a cationic monomer copolymerizable with acrylamide is used. Examples of cationic comonomers are aminoalcohol esters of methacrylic and acrylic acid (such as dimethylaminoethyl methacrylate or diethylaminoethyl acrylate) and the salts of quaternary ammonium salts thereof; and ΊΤ-aminoalkyl substitution products of methacrylamide or acrylamide (such as IT-methaeryloyl-EP, IT'-dimethyl-i, 3-diaminopropane or H-acryloyl-I ', IJ'-dimethyl-i, 1-dimethyl-1 ₉ 3 diaminopropane) and the salts or quaternary ammonium salts thereof,

Execution example

The following reference examples and examples illustrate the invention, »

Reference Example I ₁

A 70% aqueous solution of acrylamide was prepared by heating from commercially available acrylamide crystals and distilled water. The solution was cooled to 5 ^° C to precipitate acrylamide crystals. This recrystallization process was repeated to obtain purified acrylamide. To the purified acrylamide was added ET-acryloylacrylamide in an amount of 1,3,6,10,20,30 or 50 ppm _$ based on the weight of the acrylamide. According to the polymerization instructions given below, nonionic, anionic or cationic polymers were prepared flocculation

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high molecular weight and tested for their water solubility. The results are given in Table 1,

Hihionic polymeric flocculants;

A) Acrylamide was dissolved in distilled water to a concentration of 20% by weight. Then, 500 g of the aqueous solution was taken out and nitrogen was bubbled to remove any dissolved oxygen present. At 30 ⁰ C to this was 9.8 mg ammonium persulfate and 2.2 mg Eatriumbisulfit and led through the implementation, 'while was allowed to rise through the polymerization temperature and the polymerization was allowed to proceed by the action of the temperature rise. When no increase in temperature was observed, the reaction mixture was allowed to stand for an additional hour to complete the polymerization. This gave an agarike mass consisting of an acrylamide polymer and water,

, The agar-like mass was then coarsely crushed with the help of a mincer. dried in hot air for 1 hour at 100 ⁰ C and pulverized to give a powdery non-ionic polymeric flocculant for the one _s determined a molecular weight, calculated on the basis of its intrinsic viscosity, from about 7 Hill ions.

B) A non-ionic polymeric flocculant of molecular weight about 10 million was prepared by proceeding in the same manner as in A above except that the amounts of ammonium persulfate and sodium bisulfite were 6.0 mg and 1.5 mg, respectively changed.

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C) A non-ionic polymeric flocculant having a molecular weight of about 13 million was prepared by proceeding in the same manner as in vorstehend above, except that the amounts of ammonium persulfate and sodium bisulfite were made 3.5 mg and 1, respectively , 0 mg changed.

, Anionic polymeric flocculant:

An aqueous solution of a mixture of acrylamide and sodium acrylate was adjusted in a molar ratio of 80: 20 in a monomer concentration of 20 wt -% _ using acrylamide, and distilled water latriumacrylat forth.. Thereafter, 500 g of the aqueous solution were taken and nitrogen was injected to remove any dissolved oxygen present. Was added 60 mg sodium ^ 4 30 ⁰ G * azobis ~ 4-cyanovalerianat, 4.0 mg of ammonium persulfate and 2 mg to Hatriumbisulfit. The mixture was then worked up in the same manner as in the preparation of the nonionic polymeric flocculants to give an anionic polymeric flocculant having a molecular weight of about 12 million.

Cationic polymeric flocculants;

A) An aqueous solution of a mixture of acrylamide and N-metacryloyl-iP, I ', H'-trimethyl-1,3-diaminopropane chloride in a molar ratio of 90:10 in distilled water in a monomer concentration of 20% by weight was prepared. % forth "the pH of the solution was adjusted to 5.0 Thereafter, 500 g of the aqueous solution took and blowing nitrogen, to remove any dissolved oxygen present. it was at 30 ⁰ O 100 mg of sodium 4,4 ^l ~ azobis 4-cyanovalerianate, 7.2 mg of ammonium persulfate, and 3.6 mg of sodium bisulfite. The mixture was prepared in the same manner as in the preparation of the nonionic

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polymeric flocculant to obtain a cationic polymeric flocculant A containing 0.11 cation equivalents / 100 g.

A solution of a mixture of acrylamide and Methacryloylosyäthyltrimethylammoniumchlorid B) was adjusted in a molar ratio of 50: 50 and 85: 15 by weight in distilled water at a monomer concentration of 20 _# - ago%. The pH of the solution was adjusted to _5} 0 and then was dispensed, 500 g of the aqueous solution, and blowing nitrogen in order to remove any dissolved oxygen present "at 30 ⁰ C was added 100 mg Hatrium ~ 4.4 ^t ~ azobis-4 cyano-valerate, 7-2 mg of ammonium persulfate and 3.6 mg of sodium bisulfate. The mixture wurde.in the same manner as in the preparation of the nonionic polymeric flocculant worked · Auf'diese was thus obtained cationic polymeric flocculant B and B ^f, which respectively cation 0.36 equivalent / 100 g "0.16 cation equivalent e / 1 00 g contained «

Water solution 1 ^ Iieit st est y '

1 g of the powdered polymer sample was added to 1000 g of distilled water, and the mixture was stirred for 1 hour by means of a magnetic stirrer. The solution was then filtered through a 0.074 mm (200 mesh) mesh screen to remove water-insoluble fractions from the solution - · Separate and collect «The water-insoluble fraction was dried at ⁰ G and its quantity determined«

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Amount of added N-acryloylacrylamide (ppm drawn on acrylamide) ^

10 20 30 50

•! Type of polymeric acrylamide-N. flocculant χ O O O O O O O View ionic polymeric flocculant (molecular weight i about 7 million) O O O O O O O as above (molecular weight: about 10 million) O O O O O O O as above (molecular weight: about 13 million) O O O O O O O Anionic polymeric flocculant (molecular weight: about 12 million; O O O A X X X Cationic polymeric flocculating agent A (cation equivalent: 0.11 equivalents / 100 r) P O Δ X X X X as above B (cation equivalent: 0.36 equivalents / 100 g O Δ X X X X X as above B ¹ (cation equivalent: 0.16 equivalents / 100 g)

In the above table, the evaluation of water solubility is as follows:

Γ) ι the amount of water-insoluble fraction is less ^w . than 0.2 %

/ \ : the amount of water-insoluble fraction is 0.2 to 2.0 %

X ι the amount of water-insoluble content is more than 2.0%.

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Methylenebisacrylamide weighing 1, 1.5, 3, 6, 10 ppm, based on acrylamide, was added to pure acrylamide obtained in the same manner as in Reference Example 1. Using the obtained polymer flocculant, the same water solubility test as in Example 1 was carried out. The results are given in Table 2 «

Table 2

Amount of added Methylenbisacrylamids (ppm based on

Acrylamide) 0.6 1.5 3 6 10

Type of polymeric acrylamide-S. flocculent O O Δ χ X Nonionic polymeric flocculant (molecular weight: about 7 million O O Λ χ X Like oBöS (molecular weight: about 10 million) O Δ X χ X As above (molecular weight, about 13 million) O O χ X X Anionic polymeric flocculant (molecular weight: about 12 million) O O χ X X Cationic polymeric flocculant A (cation equivalent: 0.11 equivalents / 100 g O O Δ X X as above B (cation equivalent: 0.36 equivalents / 100 g O O Δ X X as above B ¹ (cation equivalent: 0.16 equivalents / 100 g

The water solubility assessment was carried out according to the same standards as given in the footnote of Table 1 «

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example 1

Preparation of an aqueous solution of crude acrylamide:

It charged to a reactor with 60 parts by weight of Raney copper and 1000 parts of an aqueous acrylonitrile at a concentration of 25 wt .-% and led the Urnset solution at 135 ⁰ G 4 hours at a pH of 7 to 9 by "The catalyst was prepared from the The reaction solution obtained was removed by filtering, and the residue was passed through a vacuum distillation apparatus to remove unreacted acrylonitrile and a part of the water to obtain a 50 wt% aqueous solution of acrylamide. The crude aqueous acrylamide solution contained less than 300 ppm of acrylonitrile and less than 80 ppm of copper,

Re i nigung the aqueous acrylamide solution;

Glass columns A, B and C having a respective inner diameter of 20 mm and a length of 50 cm were prepared, and the aqueous acrylamide solution was purified by the following method.

1 # 100 milliliters of a strongly acidic cation exchange resin (Amberlite IR-120B, trade name for a product of Röhra & Haas Go) was charged to column A and maintained in the Η-form. Column B was charged with 100 Milliliter of a strongly basic anion exchange resin (Diaion PA316, trade name for a product of Mitsubishi Chemicals Industries, Ltd.), and the resin was kept in the carbonate salt form. The two columns were connected in series in order A-B. The aqueous crude acrylamide solution was passed through the columns at room temperature at an hourly space velocity of 2 (200 fol / hr) and collected for 3 to 7 hours (1-a) for 12 to 16 hours

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(1-b) and 26 to 30 (1-c) fractions formed after the solution was passed through, and provided for use in the preparation of polymers and analysis of H-acryloyl-acrylamide content.

2 _e One hundred milliliters of a strongly acidic cation exchange resin (Amberlite IR 120B) was charged to the column A and maintained in the H form. One hundred milliliters of a weakly basic anion exchange resin (Lewatit MP-62, trade name for a product of Bayer AG) was charged to the column B and maintained in the free form. The two columns were connected in series in the order AB. The above aqueous solution of the crude acrylamide was aerated by blowing in air at room temperature and then the acrylamide solution was passed through columns A and B. The reaction was carried out for 3 to 7 hours (2 -a), fractions formed 21 to 25 hours (2-b) and 31 to 35 hours (2-c) after the solution was passed through were collected and used for the preparation of polymers and analysis of the U-acryloyl-acrylamide content.

3 "Column C was filled with 100 milliliters of activated carbon (Filtrasoap F400, tradename for a product of Calgon, Inc) and washed completely with water. Columns A and B were treated with the same ion exchange resins as described above 2 filled "The three columns A, B and G were connected in series in the order ABC. The above aqueous solution of the acrylamide was passed through the columns A, B and G at room temperature at an hourly space velocity of 2 (200 ml / hr), and for 4 to 8 hours (3-a), 15 to 19 hours (3-b) and fractions formed 24 to 28 hours (3-c) after the solution had started to pass through were collected and used for the production of polyols.

-1. .IUlHQ fl9 * fH s'äQ: -

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and the analysis of the W-acryloyl-acrylamide content verv / ends ♦

4 · Sine aqueous solution obtained by the same treatment as in the above 2 was heated to 40 ⁰ G, and an aqueous solution of sodium hydroxide was added while einblies air to adjust the pH of the solution to 12.8. Subsequently, the solution was allowed at 40 ⁰ O stand while air einblies 10 minutes (4-a). Thereafter, dilute sulfuric acid was added to adjust the pH of the solution to 7.0. The resulting acrylamide solution was used for the preparation of polymers and analysis

- of the N-acryloyl-acrylamide content used

The column C was charged with 100 milliliters of a weak base anion exchange resin having secondary amino groups (Diaion WA-20, trade name for a product of Mitsubishi Chemicals, Ltd.) and the free-form anion exchange resin by the same treatment as under 2, by the column C at room temperature with an hourly space velocity of 2 (200 ml / h). The times 1 to 5 hours (5-a), 11 to 15 hours (5-b) and Fractions formed 26 to 30 hours (5-c) after starting the solution were collected and provided for use in the preparation of polymers and analysis of the IT acryloyl-acrylamide content.

6, 500 parts by weight of an aqueous acrylamide solution obtained by the same treatment as in 2 above were washed with 100 parts of chloroform (6-a) or 100 parts of carbon tetrachloride (6-b) and then for use in the production of polymers and the like Analysis of the H-acryloyl-acrylamide content provided.

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7 x 100 milliliters of a strongly acidic cation exchange resins s, Amberlite IR-120B, maintained in the H-Porm, and 100 milliliters of a strongly basic anion exchange resin, Diaion PA316, maintained in a Garbonatsalzform _s were well mixed, and the mixture was divided equally and in the columns A and B filled. The columns were connected in series in the order AB. The above aqueous solution of the crude acrylamide was passed through columns A and B at room temperature at an hourly space velocity of 2 (200 ml / hr). The fractions formed during 3 to 7 hours (7-a), 12 to 16 hours (7-b) and 26 to 30 hours (7-c) after starting the solution were collected and for use in the preparation of polymers and analysis of the 1-acryloyl-acrylamide content.

Method r Bildun gvon polymers and method of examining the water solubility ^

A polymer was prepared according to the method described in Reference Example 1 and the water solubility of the resulting polymer was examined.

Method for the analysis of 1-acryloyl-acrylamidst

The acrylamide prepared in Reference Example 1, which contained a known amount of H-acryloylacrylamide, was extracted with chloroform containing a predetermined amount of dimethyl phthalate used as an internal standard. The chloroform layer was separated and concentrated, and a calibration curve of N-acryloyl-acrylamide was prepared using gas chromatography. Using the calibration curve, the content of IT-acryloyl-acrylamide in the above aqueous solution of the purified acrylamide

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certainly·

Table 3 shows the relationship between the content of the IT-acryloyl-acrylamide in a polymer and the water solubility of the polymer.

Table 3

Type d. purified

Acrylamide 5-a 6-a, 5-b 6-b 5-c 3-a 1-a 4-a 3 -b 3-c 1-b 7-a 2 ~ c 2-a 2-b 7-b 1 ~ c 7-c Content of IJ-acryloyl-acrylamide (ppm based on acrylamide) 0.5 0.5 0.8 1.3 2.0 3.5 4.1 7.3 8.7 15.2 23 £ 24.0 27.0 27.5 28.7 35 ₉ 3 41 /) Φ, Type d * polymeric ^N flocculant "

y _? Acry lamids y ρ,

not ionic β-polymeric flocking agent

",, 4-4- ~ τ i'rv. ^ N ^ v., Η" ^ IJ v_y W v ^ ^v - ^

medium (molecular

weight about 7 MJlU ₁₁ ) __ ™ .._________ _ «_

Sw """" i? S ^ar "QQ oooo oooooo ooooooo

^v £ Llt ^a * ifiiif "Ό 0 0 0 0 O O OO O OO O 'OO OQO

Anionic polyme- _ _ _{Λ Λ} ' _Λ ^^^ • -ν ^ ->, / -ν s * \ r \ r \

res flocculant QOOOOOOOOOOO O O O O OO

Molekulargew.etwa

12 million) __._ _ "___" _.

Kai ionic polymeric flocculant ^ / - SnOO-OOOO-XX XXXXXXX (cation equivalent KJ vJ ^ Wv- / vji> ro

0,11 Ä q uva le nt e / .100g_) _ "__, ^" _ ^> ^ <i

as above (Tat ion ο ⁰ ^ ¹

Equivalent-.36 Equi-O OOOO ΔΔΧ X XX X X X X X X X ^ q- *

valente / 100 g) _____.,,., 'ro

as above "Tkat ion. * co ^ ro

equivalent: 0.16 eq. Q OOA ^ J ^XXXX XXX XXXXXX ro valente / 100 g) __.

* V? Q 7 6 5 " ² ^ 27.5.1982

OL · Ό I V ^ AP G 08 P / 232 976/5

59 704/18

Reference Example 3

Was carried out using an attempt to produce non-ionic, anionic and cationic polymers by using an aqueous solution of acrylamide, which ise in the same W _e as in Example 1 (4) was treated, except that the time period during which was allowing to stand the solution while blowing air at 40 ⁰ C, changed to 1 hour (4-b) or 4 hours (4-c) "the Eolymeri- but was sationsgeschwindigkeit so low that the polymerization was not completed _β

Example 2

The same glass columns A, B and C were provided as in Example 1. Column A was 100 milliliters. of a strongly acidic cation exchange resin, Amberlite 1R-12OB, filled in the Η-form. Column B was filled with 100 milliliters of a strongly basic anion exchange resin, Diaion PA316, in the 0H form and column G was charged with 100 milliliters of a weak acid cation exchange resin (Lewatit GlTP-80, trade name for a Bayer AG product) in the Η -Shape. The three columns were connected in series in the order ABC. The same aqueous solution of the crude acrylamide as used in Example 1 was passed through columns A, B and G at 18 ^° C. at an hourly space velocity of 2 (200 ml / hr). The fractions formed during 3 to 7 hours (8-a), 21 to 25 hours (8-b), and 41 to 45 hours (8-c) after the solution was passed were collected and analyzed for their M-acryloyl-acrylamide content , The content of N-Acryloy! Acrylamide was less than 0.5 ppm in all these fractions. "

6 _r Q -28- 27.5.1932

ΔΡ C 08 F / 232 976/5 59 704/18

Seven types of polymers from these fractions were prepared in the same way as in Example 1. 1 ago and examined them with regard to the water solubility it. All of these polymers were found to contain less than 0.2 % of a water insoluble portion.

Example 3

The same glass columns A ₃ B and G as used in Example 1 and a glass column D having an inner diameter of 23 mm and a length of 2 m were provided. "Columns A and B were each charged with 100 milliliters of a strongly acidic ion exchange resin IR-120B,. in H form and column G, filled with 100 milliliters of a weakly basic anion exchange resin, Lewatit MP-62, in free form. "Column D was packed with stainless steel Raschig rings. The four columns were placed in series in the ADBC order related the same aqueous solution of the crude acrylamides, as used in example 1, at 20 ⁰ G and an hourly space velocity of 200 ml / hr "* slides through the columns a, D and C ₅ B. A small amount of sodium hydroxide was continuously introduced from the inlet of column D to maintain the aqueous acrylamide solution at the inlet of column D at a pH of 12.5 to 12.8. The fractions formed during 8 to 12 hours (9-a), 28 to 32 hours (9-b), and 48 to 52 hours (9-c) after starting the solution were collected and analyzed for their I-acryloyl-acrylamide content "For all these fractions, the N-acryloyl-aerylamide content was less than 0.5 ppm β

Seven polymer types were formed from the fractions in the same manner as in Reference Example 1, and their water solubility was examined. All of these polymers exhibited a water-insoluble content of less than 0.2% e.

Claims (7)

Z j Z J / ö D Berlin, 27.5.1982 AP G 08 F / 232 976/5 59 704/18 invention claim 1. A process for the preparation of a polymeric flocculant by polymerization of acrylamide, obtained by catalytic ^ hydration of acrylonitrile with water in the presence of a metallic copper catalyst at a pH of 4 to 10, a temperature of 50 to 150 ⁰ G and at a pressure of atmospheric pressure to to an elevated pressure of up to about 10 kg / cm, characterized in that one obtains by catalytic hydration The crude, aqueous acrylamide solution substantially freed from IJ-acryloyl-acrylamide and polymerized the acrylamide contained therein to obtain a high molecular weight cationic flocculant of the acrylamide type. 2. The method according to item 1, characterized in that the concentration of the N-acryloyl-acrylamide. in the acrylamide to be polymerized is not more than 10 ppm based on acrylamide. 3. The method according to item 1, characterized in that the concentration of N-acryloyl-acrylamide in the acrylamide to be polymerized is not more than 5 ppm based on acrylamide, 4. The method according to item 1, characterized in that the concentration of the H-acryloyl-acrylamide in the acrylamide to be polymerized is not more than 1 ppm based on acrylamide. 5. The method according to item 1, characterized in that the crude acrylamide of H-acrylamide-acrylamide by physical AP G 03 P / 232 976/5 59 704/18 cationic adsorption, reactive adsorption, chemical reaction degradation, and solvent extraction, either in or substantially in combination, 6. The method according to item 5, characterized in that the reactive adsorption is carried out by using a strongly acidic cation exchange resin, a weakly basic anion exchange resin and then a weakly basic anion exchange resin having primary and / or secondary amino groups, Process according to point 5 _3, characterized in that the aqueous acrylamide solution is subjected to a reactive adsorption and subsequently to a solvent extraction. 8 "Process according to item 7, characterized in that the reactive adsorption is carried out by using a strongly acidic cation exchange resin and then a weakly basic anion exchange resin, 9, method according to item 8, characterized in that the solvent extraction is carried out using chloroform or carbon tetrachloride. 10c method according to point 5 _S, characterized in that first the reactive adsorption is carried out using a strongly acidic cation exchange resin and then a weakly basic anion exchange resin and then the physical adsorption is carried out » Q 7 S 5 ^ " 27.5.1932 Ό i U * ·> A? G 08 P / 232 976/5 59 704/18 1T, method according to item 10, characterized in that the physical adsorption is carried out using activated carbon. 12. Method according to item 5, characterized in that the aqueous acrylamide solution is first treated on a strongly acidic cation exchange resin and then on a weakly basic anion exchange resin. Process according to item 5 _9, characterized in that the aqueous acrylamide solution is treated with a strongly acidic cation exchange resin and then with a weakly basic anion exchange resin and thereafter subjected to decomposition by chemical reaction. .14. Process according to item 13, characterized in that the decomposition is carried out by chemical reaction using an alkali. Method according to item 5 _S, characterized in that the reactive adsorption is carried out using a strongly acidic cation exchange resin, a strongly basic anion exchange resin and then a weakly acidic cation exchange resin » Method according to item 5, characterized in that first the reactive adsorption is carried out using a strongly acidic cation exchange resin, thereafter the decomposition is carried out by chemical reaction using an alkali and finally the reactive adsorption using a strong acid cation exchange resin and then a weakly basic anion exchange resin is carried out. For this 1 sheet diagrams