JPS6024125B2 - Method for producing acrylamide polymer - Google Patents

Description

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

More specifically, the present invention relates to a method for producing a partially hydrolyzed acrylamide polymer having excellent solubility and flocculation performance from acrylamide obtained by hydrating acrylonitrile in the presence of a copper-containing catalyst. Since polyacrylamide has excellent flocculating performance, it has various uses such as a flocculant and a paper strength enhancer, and various methods for producing the polyacrylamide are known. Conventionally, most of the acrylamide that has been obtained industrially has been produced by a method called the sulfuric acid method, in which acrylonitrile is hydrated with sulfuric acid to form acrylamide sulfate, and then neutralized with ammonia. A method has been developed to produce acrylamide by direct hydration using a steel-containing catalyst. According to this method, by-products such as ammonium sulfate are not produced, and the manufacturing process can be closed, and it is considered to be an industrially advantageous manufacturing method compared to conventional methods.

However, when acrylamide produced by the sulfuric acid method and acrylamide produced by the contact hydration method are polymerized under specific conditions, the polymerization behavior and the properties of the resulting polymers may differ. When polyacrylamide is obtained by aqueous solution polymerization, it is preferable to carry out the polymerization at a higher concentration in order to improve productivity and to ultimately obtain polyacrylamide as a powder.

Moreover, from the viewpoint of solubility of the obtained polymer, the polymerization system is generally carried out under alkaline conditions. By the way, it has been found that if the contact water utilization method acrylamide is polymerized according to the conventional common sense and the same polymerization recipe as before, the polymerization time will be significantly increased, and the quality of the obtained polymer will also deteriorate. .

Furthermore, it has been found that this unfavorable phenomenon is further aggravated when a hydrolyzing agent is added during polymerization to cause hydrolysis to occur simultaneously with polymerization, so-called co-polymerization hydrolysis. The reason for this is probably that the difference in the amount of impurities originating from the production of acrylamide affects the polymerization reaction. Impurities in acrylamide using this contact hydration method are
Since it is a noisy substance, it is almost impossible to remove it using industrial-scale purification methods. In view of these circumstances, the inventors of the present invention conducted intensive studies and conducted simultaneous hydrolysis of the monomer containing the above-mentioned significant impurities at a high concentration to obtain water solubility equivalent to that of the subordinate monomer. In order to obtain a polyacrylamide partial hydrolyzate having This discovery led to the present invention.

That is, the present invention uses a monomer containing a predominant amount of catalytic acrylamide obtained by hydrating acrylonitrile using a copper-containing catalyst in an aqueous solution having a concentration of 10 to 3% by weight.
Peroxy compound (Per.) and amine reducing agent (Re
d. ), when the concentration of the redox initiator is expressed in mol% relative to the single star, the concentration used is [Re
d. ]/[Per. ] = 15-1000 [Red. 〕×
[Per. ] = 0.5 x 10-4 ~ 50 x 10-4 [P
er. ]=5xlo-4 to 100x10-4, and polymerization is carried out in the presence of a hydrolyzing agent.

Typical examples include triaminepentaacetic acid, triethylenetetraminehexaacetic acid, and salts thereof, and any other substances generally used for similar purposes may be used. In the present invention, it is possible to polymerize acrylamide and simultaneously carry out a hydrolysis reaction to produce a partially hydrolyzed acrylamide-based polymer in a high concentration, high molecular weight polymerization system.

For example, a combination of boric acid and caustic soda may be used as a chemical for this purpose, but other known hydrolyzing agents may also be used depending on the situation.

As described above, the present invention uses a specific redox polymerization initiator containing a large excess of reducing agent relative to the peroxy compound, but other parts can be added by appropriately selecting known methods. . Specifically, the polymerization is carried out, for example, as follows.

That is, take an aqueous monomer solution of approximately 10 to 3% by weight in a dewar bottle, add a metal chelating agent and an azo catalyst as necessary, and then sequentially add and mix the above-mentioned Dox-based polymerization initiator to initiate polymerization. Let it start. It is preferable to replace oxygen in the polymerization system with an inert gas such as nitrogen gas prior to polymerization. Either the oxidizing component or the reducing component of the polymerization initiator may be added first, but it is preferable that both are added in the form of an aqueous solution. The appropriate polymerization initiation temperature is usually 0 to 5,000.

When carried out under these conditions, polymerization takes place within 1 to 3 minutes after addition of the initiator.
It completes in time and produces a hard gel-like polymer. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

In addition, "%" and "part" in the examples are each expressed based on weight.

Example 1 40 parts of acrylamide (AA) aqueous solution (concentration 50%) by contact hydration method and 376 parts of ion-exchanged water were charged into a polymerization container, and 2.4 g of boric acid (0.0% by weight, based on liquid) and 1.6 g of caustic soda (0.2% by weight, relative to the liquid) were added.

Next, the temperature of the above mixed solution was maintained at 25oC while the air was sufficiently replaced with nitrogen gas, and dimethylaminopropionitrile (DMPN) was added at 800 °C (2900 x 10-4
Add 10 parts of potassium persulfate (KPS) dissolved in water, then add 8 parts of potassium persulfate (KPS) (10.5 x 10-4 mol%) dissolved in 1 part of water. Added.

After a yield period of about 15 minutes, the polymerization proceeded rapidly and reached the maximum temperature (about 90 ○) in about 9 minutes, and the polymerization was completed. At this point, the gel-like polymer obtained was taken out and
After heating for 1 hour in an air chamber of 0.0°C, the gel-like polymer was taken out and coarsely crushed into approximately 3 x 3 ribs in column 3.
Hot air drying was performed at 0 for 1 hour to obtain a dried product. As for the physical properties of this polymer, the viscosity of a 0.1% aqueous solution was 55 ratio p, and the hydrolysis rate was 9%.

When 0.5 to 1 polymer was added to papermaking wastewater whose pH was adjusted to 6.5 to 7 by adding 30 to 5 carbonaceous acid, the polymer showed good flocculation performance. Example 2 Example 1 was repeated except that the indicated amounts of boric acid and caustic soda (adjusted to 800 parts total with ion-exchanged water) were used.

Changes in the hydrolysis rate over time were measured by changing the heat treatment time. Table I Comparative Example 1 Addition amount of D-Yanaka N 32-9 (40 traces), KPS32-9
Polymerization was carried out in the same manner as in Example 1, except that the amount was changed to (40 ppm).

After an induction period of approximately 15 minutes, the polymerization proceeds slowly to approximately 4
The maximum temperature (approximately 9,000 ℃) was reached in ~5 hours and the polymerization was completed. The physical properties of the obtained polymer are as follows: viscosity of 0.1% aqueous solution is 4.
The ratio p was 0, and the hydrolysis rate was 12%. A flocculation test using paper manufacturing wastewater was conducted under the same conditions as in Example 1, but the performance was poor. Examples 3 to 8 Comparative Examples 2 to 4 Polymerization was carried out in the same manner as in Example 1, except that the composition of the monomer aqueous solution, the type and amount of the initiator, and the stars of additives such as hydrolyzing agents were changed as shown in Table 2. , the gel was dried by heat treatment (90oC, 1 hour).

On the other hand, if a redox initiator containing, for example, 5 to 100 x 10-4 mol% of potassium persulfate and 3000 to 75 x 10-4 mol% of dimethylaminopropionitrile is used for acrylamide, polymerization will occur with respect to the conventional formulation. Time is 1/
At the same time, the viscosity of the aqueous solution of the obtained polymer increases by more than 2 times. Although the cause of this is not clear, it is thought that the impurities contained in the contact hydration method acrylamide react with a large amount of reducing agent, making it inactive for the original polymerization reaction. It will be done. In carrying out the present invention, it is necessary to use the above-mentioned redox-based initiators, but in addition, azobiscyanovaleric acid, azobisisobutyronitrile, 2,2'-azobis(4-methoxy -2.
4-dimethylvaleronitrile), 2,2-azobis(2
-amidinopropane) hydrochloride, 2,2'-azobis(2,4-dimethylvaleronitrile), and other azo-based initiators can be used in combination. Acrylamide obtained by the contact hydration method is polymerized using such an initiator, but of course the monomer may be acrylamide alone or a mixture with other copolymerizable vinyl monomers. It's okay.

Specifically, acrylic acid (salt), methacrylic acid (salt),
Vinyl sulfonic acid (salt), styrene sulfonic acid (salt),
2-acrylamide-2-methylpropanesulfonic acid (
Any vinyl compound can be used as long as it does not impair the water bathability of the polymer, such as (meth)acrylic acid ester, vinyl acetate, or acrylonitrile. When the monomers are a mixture, the proportion of acrylamide in the total monomers is preferably at least 5% by weight, particularly at least about 80% by weight.

Furthermore, when carrying out the polymerization according to the present invention, it is also possible to carry out the polymerization reaction by adding a metal chelating agent to the monomer aqueous solution.

By adding this metal chelating agent, it is possible to deal with the case where heavy metals are mixed in, and the negative effects can be removed.
Examples of metal chelating agents added for this purpose include ethylenediaminetetraacetic acid and diethylene.Specifically, peroxy compounds used in the present invention include persulfates such as potassium persulfate and ammonium persulfate, and sodium bromate. , potassium bromate, sodium chlorate and potassium chlorate, oxyhalogen salts, sodium perborate, sodium percarbonate, hydrogen peroxide, pensoyl peroxide, cumene hydro/gu oxide, ditertiary butyl hydroperoxide There are peroxy compounds such as

The amount of this peroxy compound used is 5% per monomer.
~100 x 104 mol%, preferably 8.5-6010
-4 mol% is appropriate; if the amount is less than this, the polymerization time may be delayed or unreacted monomers may remain, which is undesirable. On the other hand, if the amount is more than this, it will be difficult to control the polymerization and the molecular weight of the resulting polymer will be low. There is a significant decrease in

On the other hand, reducing agents for peroxy compounds include monoethanolamine, diethanolamine, triethanolamine, nitrilotrispropionic acid (salt), nitrilotrispropionamide, dimethylaminopropionitrile, dimethylaminoethanol, etc. The amount of this reducing agent used is 1 of the peroxy compound.
An amount of 5 to 1000 times the mole is required.

If the amount is outside this range, the polymerization rate will be extremely lowered or the degree of polymerization will be lowered, which is not preferable. To explain in more detail, conventionally when acrylamide is polymerized using a redox initiator, the ratio of peroxy compound to reducing agent is usually in the range of 1:1 to 3 (mole ratio). It was recognized that when trying to hydrolyze acrylamide obtained by polymerization at a high concentration during polymerization, the polymerization time was extremely long and the quality of the resulting polymer was poor.

Examples 9-10 Comparative Example 5 The same operation as in Example 3 was performed except that the amount of initiator was changed as shown in Table 2.

The above results for those other than Example 2 are summarized in Table 2.

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Claims (1)

[Scope of Claims] 1 A monomer containing a predominant amount of catalytic acrylamide obtained by hydrating acrylonitrile using a copper-containing catalyst is mixed with a peroxy compound (Peroxy compound) in an aqueous solution having a concentration of 10 to 30% by weight. When performing hydrolysis during polymerization using a redox initiator consisting of a redox initiator consisting of an amine reducing agent (Red.) and an amine reducing agent (Red. [Red. 〕／
[Per. ]=15~1000 [Red. ]×[Pe
r. ] = 0.5 x 10^-^4 ~ 50 x 10^-^4
[Per. ]=5×10^-^4~100×10^-^
4. A method for producing a partially hydrolyzed water-soluble acrylamide polymer, characterized in that polymerization is carried out in the presence of a hydrolyzing agent selected from the conditions set forth in item 4. 2. The manufacturing method according to claim 1, wherein boric acid and caustic soda are used as hydrolyzing agents.