JPS6050810B2 - Method for producing acrylamide polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an acrylamide polymer.

Specifically, the present invention relates to a method for producing an acrylamide polymer having good water solubility from an aqueous acrylamide solution obtained by catalytically hydrating acrylonitrile in the presence of a copper-containing catalyst. Traditionally, acrylamide was produced by reacting acrylonitrile with sulfuric acid to produce acrylamide sulfate, which was then neutralized, but in recent years acrylamide has been produced by directly hydrating acrylonitrile in the presence of a copper-containing catalyst. A manufacturing method was developed and became widely adopted. This method is extremely advantageous in that acrylamide can be obtained as an aqueous solution and can be directly subjected to the polymerization reaction. However, acrylamide obtained by reacting acrylonitrile with sulfuric acid is an azo compound such as dd'azobisisobutyronitrile,
Polymerization is possible using organic peroxides such as benzoyl peroxide, and inorganic peroxides such as persulfates, percarbonates, and chlorates. In order to obtain an acrylamide coagulation precipitant, it is preferable to use a persulfate and a sulfite compound as a polymerization initiator.

However, acrylamide obtained by reacting acrylonitrile and water in the presence of a copper-containing catalyst cannot be obtained by producing a polymer using the above-mentioned persulfate and sulfite compound.
The resulting acrylamide polymer has insufficient water solubility and flocculant properties, and a good acrylamide flocculant and precipitant cannot be obtained. The present inventors have proposed a method for producing an acrylamide polymer using a persulfate and a sulfite compound as a polymerization initiator from an aqueous acrylamide solution obtained by reacting acrylonitrile and water in the presence of a copper-containing catalyst;
In particular, as a result of intensive studies on the modification of the resulting polymer, we found that an acrylamide polymer obtained by reducing the amount of a specific substance in the acrylamide aqueous solution used for polymer production to a specific amount or less. The inventors have discovered that the properties can be significantly improved and have arrived at the present invention.

That is, the present invention provides 3,3',3'-nitrilotrispropionic acid (hereinafter T
(abbreviated as NPA) to acrylamide at 0.1p
This is a method for producing an acrylamide polymer, in which acrylamide is polymerized using a persulfate and a sulfite-based compound as a polymerization initiator after the particle diameter is reduced to .mu.m or less.

Any known copper-containing catalyst can be used as the copper-containing catalyst used in the production of the aqueous acrylamide solution applied to the method of the present invention, but for example, copper compounds such as copper oxide, copper hydroxide, copper salts, etc. Examples include reduced copper obtained by reduction with carbon oxide or the like, and Raney copper obtained by expanding a Raney alloy consisting of copper and aluminum, zinc, or magnesium.

Therefore, the reaction between acrylonitrile and water is carried out in the presence of the above-mentioned copper-containing catalyst in a fixed bed or in a suspended bed at room temperature to 300 ml.
It is usually carried out at a temperature of 0.000C, especially in the temperature range of 50 to 150C. Since the solubility of acrylonitrile in water is not as large as shown in the figure above, the amount of water to be used relative to acrylonitrile is usually 4
It is used in the range of multiple molar to several tens of molar. The acrylamide aqueous solution obtained by the above method is usually prepared using a strongly acidic cation exchange resin, a weakly acidic cation exchange resin, a giant reticular cation exchange resin,
It is purified using ion exchange resin etc. In the acrylamide aqueous solution obtained by reacting acrylonitrile and water in the presence of the copper-containing catalyst described above, TNPA is usually present in an amount of 0.5 ppm or more based on the generated acrylamide, and as it is, persulfate and sulfite compounds are present. When polymerizing acrylamide using a polymerization initiator, the behavior of acrylamide during polymerization, the properties of the polymer itself obtained by polymerization, and the yield. The application properties of the resulting acrylamide polymers are adversely affected, and the commercial value of the resulting acrylamide polymers is sometimes seriously impaired.

Such a phenomenon is only observed in methods using the above-described persulfate and sulfite compounds as polymerization initiators, and is unique to the polymerization initiators used in the present invention. .

Therefore, it is acceptable to produce an acrylamide polymer from an aqueous acrylamide solution obtained by reacting acrylonitrile and water in the presence of a copper-containing catalyst using a persulfate and a sulfite compound as a polymerization initiator. The amount of PA is in the range of 0.1 ppm or less relative to the acrylamide in the aqueous solution, and such a phenomenon that such a small amount of a specific substance has a very serious adverse effect is the reason for the polymerization initiation used in the present invention. This is both surprising and specific in terms of agents. TNPA is removed from an acrylamide aqueous solution obtained by reacting acrylonitrile and water in the presence of a copper-containing catalyst to reduce the amount of T to 0.1 ppm or less based on acrylamide.
There are no particular limitations on the method for removing NPA, but for example, chelate resin that has been pre-adsorbed and saturated with copper ions using an aqueous solution of copper sulfate, sulfonated carbon that has been similarly treated with a copper ion-containing solution, and the like. Strongly acidic cation exchange resins and weakly acidic cation exchange resins treated with a copper ion-containing liquid are used.

The copper ions adsorbed at this time usually have an exchange capacity of 20
A range of ~780% is preferable, but specific measures include, for example, using a resin with high adsorption in the upper stage of the adsorption tower, and using a resin with low adsorption in the lower stage, or a resin that does not adsorb copper ions. It is also possible to use The acrylamide aqueous solution (hereinafter referred to as modified acrylamide aqueous solution) whose TNPA content has been reduced to 0.1 ppm or less by the method described above is then converted into an acrylamide polymer using a persulfate and a sulfite compound as a polymerization initiator. be guided by.

As persulfates used as polymerization initiators,
Examples include potassium persulfate, sodium persulfate, ammonium persulfate, etc. The amount used is usually 0.001 to 10% by weight based on acrylamide, preferably 0.001 to 10% by weight.
The range is 0.05% by weight.

Sulfite compounds used as polymerization initiators include dithionite, sulfite, thiosulfite, pyrosulfite, and thiosulfate compounds. Ammonium dithionite, sodium dithionite, sodium sulfite,
Potassium sulfite, ammonium sulfite, sodium bisulfite, potassium bisulfite, ammonium bisulfite, methyl thiosulfite, ethyl thiosulfite, sodium pyrosulfite, potassium pyrosulfite, ammonium pyrosulfite, sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate , sodium formaldehyde sulfoxylate, etc. Among them, sodium hydrogen sulfite is particularly preferred. The amount of these sulfite compounds to be used is in the range of 0.1 to 10 mol, preferably 0.25 to 1.0 mol, per 1.0 mol of persulfate. The modified acrylamide aqueous solution according to the present invention can also be used as a monopolymer such as methacrylamide, methylolacrylamide, methacrylic acid, acrylic acid,
It can also be used as a copolymer by using dimethylaminoethyl methacrylate and methyl chloride quaternary salt of dimethylaminoethyl methacrylate, and the above acrylamide polymer can be used for various wastewater treatment such as sewage, paper treatment, etc. It is especially suitable for use as a thickener, etc. in various wastewater treatments.

The present invention will be further explained below with reference to Examples.

Note that TNPA was quantified in the Examples by the following method. Determination of TNPA in aqueous acrylamide solution: 0.
A column with an inner diameter of 10.4 T0t was filled with 30 ml of Chelate Resin 2 (manufactured by Unitika, trade name: UNISELC 30), in which 60% of the exchange capacity of copper ions had been adsorbed in advance with a 5 m01/f copper sulfate aqueous solution.

Thereafter, an acrylamide aqueous solution 10e to be quantified was passed through at a rate of 1.8' for 1 hour. Thereafter, the chelate resin was thoroughly washed with ion-exchanged water, and then the compounds adhering to the chelate resin were eluted with 100 mL of a 5% by weight aqueous solution of caustic soda. The eluted aqueous caustic soda solution was neutralized with an aqueous hydrochloric acid solution and then evaporated to dryness.The resulting solid was mixed with 100ml of methyl alcohol containing boron trifluoride.
methyl alcohol return with t. Esterification was effected by heating under flow. Next, add this methyl alcohol solution to a total volume of about 1 Tr.
It was concentrated to L1, and this was made into a carbon tetrachloride solution. After washing this carbon tetrachloride solution with a concentrated caustic soda aqueous solution, 0.
It was concentrated to a fixed amount of 5 to 1 mt and subjected to gas chromatography analysis. Gas chromatography analysis uses equipment equipped with a hydrogen flame type detector.
PEG2OM column injection temperature 250 C1 column temperature 1
Quantification was carried out under the condition that the temperature was raised from 00'C to 220°C at a rate of 4°C/Mjn.

Note that the calculation of the TNPA-methyl ester content is performed separately.
This was performed by comparison with a calibration curve determined using NPA-methyl ester. Example Production of acrylamide aqueous solution: Raney copper 2 was developed and washed with water in a 100e reactor using a conventional method.
25k9 of acrylonitrile and 25k9 of ion-exchanged water, from which dissolved oxygen had been removed by nitrogen blowing, were added to the reactor, reacted at 70°C for 2 hours, separated the catalyst, and concentrated by vacuum distillation. Crude acrylamide was obtained.

Next, Amperlite IR-12 manufactured by Tokyo Organic Chemical Industry Co., Ltd.
Copper ions were removed by passing through a column filled with hydrogen form of 0B (trade name) cation exchange resin to obtain an acrylamide aqueous solution A having a concentration of 30 wt%. This acrylamide aqueous solution A
As a result of quantifying TNPA, it was found to be contained at 0.56 ppm relative to acrylamide.

Friendly acrylamide aqueous solution: 0.5 ml 101/e (7) 30 ml of Bayer's Revachit'n) 207 (trade name) chelate resin, which had been previously adsorbed with 60% of the exchange capacity of Cu ions using a CUsO suspension solution, was placed in the upper layer. , and untreated Rebatit'IP
15m1 of 2O7 has an inner diameter of 10.4r for the lower stage!
n column and then TNPAO. 56p
10e of the above acrylamide aqueous solution A containing pm was passed through at a rate of 1.8e for 1 hour.

The amount of TNPA in the obtained acrylamide aqueous solution 1 was determined to be approximately 0.0 ppm.

Furthermore, acrylamide aqueous solution A was diluted using acrylamide aqueous solution 1, and the amount of VNPA was reduced to 0.06 ppm.
An acrylamide aqueous solution was obtained, which was designated as an acrylamide aqueous solution (■). Furthermore, an acrylamide aqueous solution with the TNPA amount adjusted to 0.20 ppm was obtained in the same manner.
This was designated as acrylamide aqueous solution (■). Production of acrylamide polymer: Dilute the acrylamide aqueous solution to a 20 wt% acrylamide aqueous solution, and pH it with a sodium hydroxide aqueous solution.
Adjusted to 7.

Take 298y of this solution, remove dissolved oxygen by bubbling it with nitrogen for 1 hour, and then add 1ml of ammonium persulfate aqueous solution.
1 (containing 2.7 x 10-5 m01) of an aqueous sodium hydrogen persulfate solution (1 wL1 (containing 1.35 x 10-5 m101)) was added as a polymerization initiator, and polymerization was carried out adiabatically in a nitrogen atmosphere. Immediately after the polymerization was completed, the mixture was heated in a hot water bath at 90°C for 2 hours. The obtained polymer gel was extracted with water using methanol, and then dried in three powders under reduced pressure at 50°C IOIT]MHg.
It was made into a dry powder. The obtained dry powder was then evaluated for its flocculating properties as a flocculating precipitant, and the TN
The amount of PA and polymerization time are shown in the table below along with the properties of the acrylamide polymer in terms of average molecular weight and water-insoluble content.

In addition, each evaluation in the above table was performed as follows.

Average molecular weight: The polymer powder was dissolved in a 1N aqueous sodium nitrate solution, the viscosity was measured using a capillary viscometer, and the molecular weight was calculated from the intrinsic viscosity.

Water-soluble content of polymer: 0.1 wt% of acrylamide polymer powder dissolved in water
The concentrated aqueous solution was passed through a 200-mesh furnace cloth, the gel-like substance remaining on the cloth was thoroughly washed off after passing through the temperature range, and then dried and weighed to determine the water-insoluble content.

Coagulation properties: Add 400 ppm of sulfate band to Kraft valve wastewater.
At H6, acrylamide polymer powder was added to the above waste water at a concentration of 1 ppm, and the mixture was aggregated using a jar tester in a conventional manner, and the size of the flocs produced was evaluated.

In the above table, the o mark indicates that a floc with a diameter of 3 to 47 m is formed, the Δ mark indicates that a floc of 1 to 3 gourds in diameter is formed, and the x mark indicates a diameter of 1? This indicates that less flocs are formed.

Claims (1)

[Claims] 1 3,3',3 in acrylamide aqueous solution obtained by reacting acrylonitrile and water in the presence of a copper-containing catalyst
A method for producing an acrylamide polymer, which comprises reducing the amount of ``-nitrilotrispropionic acid to 0.1 ppm or less relative to acrylamide, and then polymerizing acrylamide using a persulfate and a sulfite-based compound as a polymerization initiator.