JPS6011963B2 - Manufacturing method of acrylamide polymer - Google Patents

Description

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

Acrylamide-based polymers are widely used as flocculants, and are usually easily produced by polymerizing an acrylamide-containing aqueous solution in the presence of a catalyst.

However, the polymerization of acrylamide is an exothermic reaction, and if the concentration of the aqueous monomer solution is too high, the temperature within the polymerization system will become too high, resulting in thermal deterioration of the produced polymer. Therefore, the concentration of the monomer aqueous solution is usually 10
-35% by weight, and the polymer obtained by polymerizing this is a gel-like material with a water content of 90-65% by weight. Usually, this gel-like polymer is granulated into granules with an average particle size of 2 to 5 mm using an extrusion granulator, and then dried to produce a product.
Since gel-like polymers have high adhesiveness, they have problems such as difficulty in granulating them and severe adhesion of granules to each other or to the walls of the apparatus during the transfer process, drying process, etc. after granulation. In view of the above circumstances, the present inventor conducted various studies in order to obtain granules with relatively low stickiness when granulating a hydrogel polymer obtained by aqueous solution polymerization, and found that a specific water content and particle size was obtained. The present invention was completed based on the knowledge that the above-mentioned drawbacks can be improved by adding an acrylamide-based polymer having the following properties to perform the above-mentioned granulation.

That is, the gist of the present invention is to polymerize an acrylamide-containing aqueous solution with a monomer concentration of 10 to 35% by weight in the presence of a catalyst, and to obtain a gel-like polymer having a water content of 90 to 65% by weight on average using an extrusion granulator. When granulating into granules with a particle size of 2 to 5 m/m, a finely divided acrylamide polymer having a water content of 15% by weight or less and a particle flea of 1 m/m or less based on the gel-like polymer. A method for producing an acrylamide polymer, which comprises adding and mixing 0.5 to 20% by weight of acrylamide-based polymers.

The present invention will be explained in detail below.

The monomer targeted by the present invention can be copolymerized with acrylamide alone or with acrylamide, such as acrylic acid, sodium acrylate, 2-acrylamide propasosulfonate, or quaternary salt of jetylaminoethyl methacrylate. Mixtures with known monomers may be mentioned, but in the case of copolymerization, it is usually preferable that the proportion of acrylamide is 50 mol% or more.

The concentration of the monomer aqueous solution is 10 to 35% by weight, preferably 20 to 3% by weight; if this concentration is too low, the resulting gel-like polymer will have high stickiness, and if it is too high, the temperature in the polymerization system will increase. is undesirable because it becomes too high and causes thermal deterioration of the polymer. Examples of the polymerization catalyst include azo compounds such as azobis(2-amidinopropane) hydrochloride, peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide, sodium sulfite, ferrous sulfate,
Reducing agents such as ferrous chloride may be mentioned;
More than one species may be used in combination.

The amount of catalyst used is usually 100 to 100% of the monomer.
0 gong blood, preferably 200-500 meadow blood. Polymerization is usually carried out by degassing the above monomer aqueous solution with N2 gas, adding a catalyst, and maintaining the temperature at -10 to 100 qo.

In the present invention, the gel-like polymer obtained by polymerization is granulated using an extrusion granulator, particularly a meat grinder type extrusion granulator, and at this time, finely granulated acrylamide polymer that has been dried is added and mixed. is an essential requirement.

The finely divided acrylamide polymer to be added preferably has the same composition as the type of polymer to be produced.

The water content of the particulate polymer is less than 15% by weight, preferably less than 1% by weight, and its particle size is less than lm/cm, preferably less than 0.5 lm/skin, particularly preferably 0.2 lm/skin.
It is below the /skin level. If the water content of the particulate polymer is too high, the tackiness of the gel polymer cannot be sufficiently improved. In addition, if the particle size is too large,
This is not preferred because the gel-like polymer cannot be formed into good granules. Although the particulate polymer used in the present invention may be prepared using other polymerization systems, it is usually preferable to classify or, if necessary, crush a product polymer obtained in the same manufacturing process and recycle it.

Particularly, in the normal manufacturing process, fine particles are produced as by-products and it is difficult to dispose of them, so this method is preferable because it can also be used to treat the formed fine particles. The amount of the above-mentioned fine particulate polymer added is 0.0% relative to the gel polymer.
The amount is 5 to 2% by weight, preferably 2 to 15% by weight. If the amount added is too small, it will not be possible to improve the adhesion when the gel polymer is granulated, and if it is too large, granules will be formed. This is not preferable because it will not be possible to form the material well.

The addition of the particulate polymer is usually carried out by placing the polymer together with the hydrogel polymer in the hopper of a meat grinder type extrusion granulator and kneading the two as uniformly as possible.

The average particle diameter of the granules obtained with the extrusion granulator is 2 to 5 m.
/ is. The gel-like polymer granulated in this way is then sent to a dryer for drying treatment, but when a part of the acrylamide component is to be hydrolyzed, the gel-like polymer is dropped onto a fly, caustic soda, caustic potash, and soda carbonate are used. Alternatively, drying treatment is performed after contacting with an aqueous solution of potassium carbonate.

The drying process is usually 40 to 130 qo, preferably 60 to 130 qo.
It is carried out at a temperature of 110 qo until the water content is below 15% by weight, preferably below 1% by weight.

Since some polymer particles adhere to each other during the drying process, it is preferable to lightly crush the adhered particles during or after drying. After drying, the polymer is classified, and the particle size is usually 0.2 to 5 particles per particle, preferably 0.5 to 3 particles.
The particulate matter from the skin is recovered as a product, the large particulate matter is re-ground, and the fine particulate matter is recycled to the above-mentioned meat grinder type extrusion granulator. As described above, according to the present invention, the adhesion of the granular polymer obtained by molding a gel-like polymer with a high water content is significantly improved. This has the effect of reducing adhesion of polymer to the walls of the device. It is also useful for treating by-product fine particulate polymers, which have traditionally been difficult to treat.
The industrial effects of adopting the method of the present invention are significant.
Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 900k of 25wt% acrylamide aqueous solution in a polymerization reactor
After charging 9 and degassing with N2 gas, 2,2-azobis(2-amidinopropane) hydrochloride 20 was added as a polymerization catalyst.
0.0 ■ blood and 20 g of acidic sodium sulfite were added, and polymerization was carried out at a polymerization initiation temperature of 2,000 for 5 hours.

The obtained gel-like polymer and an acrylamide polymer with a water content of 1 t% and a particle size of 0.2 mm/mm or less (2.5 M% based on the gel-like polymer) were combined. It is fed to the hopper of a meat grinder-type extrusion granulator, and the two are mixed to produce a particle size of 2~
Granules of 5 m/skin were molded.

The granular polymer thus obtained was subjected to an adhesion test and the results shown in Table 1 were obtained.

Examples 2 to 3 Similar tests to those in Example 1 were conducted by changing the amount of the particulate polymer added during the process as shown in Table 1.

Comparative Example A test similar to that of Example 1 was conducted without adding the particulate polymer during the process.

Table 1 G Note) Adhesion test 500 g of the granulated gel polymer was placed in a plastic bag.
After compressing with lk9/your pressure from top, bottom, left and right,
The gel-like polymer was taken out, its state was observed, and it was judged according to the following criteria.

○...Almost no granules adhere to each other.

△・・・The granules are sticky to each other, but can be easily loosened when squeezed by hand.

×...The granules are stuck to each other, and when pulled apart, the strings are pulled and they come apart.

Claims (1)

[Claims] 1 Water content 9 obtained by polymerizing an acrylamide-containing aqueous solution with a monomer concentration of 10 to 35% by weight in the presence of a catalyst
When granulating 0 to 65% by weight of a gel-like polymer into granules with an average particle size of 2 to 5 m/m using an extrusion granulator, the water content is 15% by weight or less with respect to the gel-like polymer, Moreover, the method for producing an acrylamide polymer is characterized by adding and mixing 0.5 to 20% by weight of a finely divided acrylamide polymer having a particle size of 1 m/m or less.