JPS5938242B2 - Production method of acrylamide polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a water-soluble acrylamide polymer with improved tackiness, and in particular to a process for drying a water-containing gel of a water-soluble acrylamide polymer to a pulverizable state. The present invention relates to a method for producing an acrylamide-based polymer that can improve the adhesion of the polymer and can be dried efficiently.

Acrylamide polymer, partial hydrolyzate of acrylamide polymer, or cationic material containing acrylamide,
Water-soluble polymers such as anionic or nonionic copolymers (hereinafter collectively referred to as acrylamide polymers) have recently been in demand as paper strength agents, sticky agents for papermaking, and flocculants for water treatment. is increasing significantly. Various methods are known for polymerizing acrylamide-based polymers, such as aqueous solution polymerization, reverse-phase suspension polymerization, and precipitation polymerization. Aqueous polymerization is the most widely used method.

In the aqueous solution polymerization method, it is desirable to increase the starting monomer concentration during polymerization in consideration of economic efficiency in the polymerization step or drying step. However, as the concentration is gradually increased, the polymer becomes a highly viscoelastic gel and becomes difficult to handle as a fluid.

Therefore, after coarsely crushing such a highly viscoelastic gel, it is dried using a rotating cylindrical dryer or a belt dryer.
A possible method is to produce a powdered polymer that is easy to handle and easily dissolves in water by subsequently pulverizing the dry particles. However, the problem with using this method is that
Due to the tackiness of the polymer gel being handled, the adhesion to other substances and the adhesion between polymer gels increases significantly, which poses a major obstacle in the drying operation. In order to solve these problems, the present inventors extruded a highly viscoelastic gel through a perforated plate and extruded the gel before passing through the perforated plate, as shown in Japanese Patent Application Laid-open No. 49-135253. Alternatively, the inventors have invented a method in which the gel particles are subsequently subjected to a cutting action to form mutually adhered gel pellets, and this aggregate is dried with hot air under conditions where shearing force is applied.

According to this method, the objective has been achieved to some extent, and hydrogels of anionic or nonionic polymers can now be treated relatively well. However, since hydrogels made of cationic polymers generally have much greater adhesion than anionic or nonionic polymers, even with the above method, the adhesion between polymer gels is remarkable and good. The drying operation was difficult. The present inventors have conducted intensive research to reduce the stickiness of cationic acrylamide copolymer gel and to make the method shown in JP-A-49135253 mentioned above possible.
When producing acrylamide polymers, by adding polyethylene glycol as an additive during polymerization, the stickiness of water-soluble acrylamide polymer gels can be significantly reduced, allowing for crushing and drying with almost no mutual adhesion. We found that it is possible to operate.

Furthermore, when the present inventors attempted to apply this technology to the production of anionic or nonionic acrylamide (co)polymers, they found that the stickiness was further reduced compared to conventional (co)polymer gels, and they were easier to dissolve. The operability of crushing and drying was further improved, and it was found that the agglomeration caused by adhesion of some (co)polymers inside the dryer, which had been observed up to then, was almost completely eliminated. The present invention is based on the above findings, and it is based on the fact that when obtaining a water-soluble acrylamide polymer or copolymer in the form of a hydrous gel, a high concentration of monomers is subjected to aqueous solution polymerization in the presence of polyethylene glycol. This is a method for producing a water-soluble acrylamide polymer with improved adhesive properties.

The acrylamide polymer gel that is the object of the present invention has almost no fluidity and needs to have a certain degree of hardness.

If the starting monomer concentration during polymerization is too low, the polymer gel will become soft, making it difficult to treat the hydrogel. For example, in the case of an acrylamide polymer having an average molecular weight of about 8 million, the lower limit of the starting monomer concentration is about 18% (by weight). Acrylamide-based polymers to which the present invention is applied include polyacrylamide, partially hydrolyzed polyacrylamide, and water-soluble copolymers of acrylamide and other vinyl monomers.

Monomers that can be used as comonomers with acrylamide include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminohydroxypropyl acrylate,
Cationic vinyl monomers such as dimethylaminohydroxypropyl methacrylate, dimethylaminoethyl acrylamide, etc., and alkyl...
Cationic vinyl monomers made into quaternary ammonium salts with quaternizing agents such as lard and dialkyl sulfates, nonionic monomers such as acrylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, and methacrylamide, and acrylics. Examples include anionic monomers such as acids, methacrylic acid, and salts thereof. The average molecular weight of polyethylene glycol, which is an additive used in the present invention, is 3
0,0-10000001 preferably 1000-200
00 is suitable.

When polyethylene glycol having a relatively low molecular weight with an average molecular weight of about 300 to 1000 is added, it shows some improvement effect compared to the case without addition, but when the average molecular weight is 1000
It is preferable to add 20,000 to 20,000 because the most significant effect is exhibited. On the other hand, the average molecular weight is about 10
As a result of trying to use polyethylene glycol (polyethylene oxide) with an ultra-high molecular weight of 00,000, the effect of reducing stickiness was comparable to that of low-molecular-weight polyethylene glycol with an average molecular weight of 1,000 or less, but the drawback was that the ultra-high molecular weight polymer Since it is dissolved in the monomer solution beforehand, the viscosity of the monomer solution increases, which is undesirable in terms of polymerization operation. The amount of polyethylene glycol added in the present invention is 0.05 to 10%, preferably 0.1 to 5% to the monomer solution.
It is good to add it.

For anionic polymers, nonionic polymers, or weak cationic copolymers with a copolymerization ratio of cationic monomers of about 20% by weight or less, a relatively low amount of polyethylene glycol should be added. That is, the effect is sufficiently exhibited even when the amount is 0.2% or less based on the monomer solution.

On the other hand, in the case of medium to strong cationic copolymers with a high copolymerization ratio of cationic monomers, even if the amount of polyethylene glycol added is low, stickiness remains to the extent that it becomes a problem in the process; By adding 0.5 to 5%, the stickiness can be reduced to the extent that good crushing and drying operations can be performed. Therefore, in the present invention, it is appropriate to determine the appropriate amount of polyethylene glycol to be added depending on the composition of the acrylamide polymer gel.

The hydrogel obtained by polymerization is dried and pulverized to obtain a powdery polymer. As described above, the present invention can be applied to cationic, nonionic, or anionic acrylamide (
This is an extremely effective method for improving the operability in the drying process of a wide range of acrylamide polymer gels, including copolymers or polyacrylamide partial hydrolysates.

Examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1 17.5 kg of acrylamide, 0.92 kg of dimethylaminoethyl methacrylate, 96% sulfuric acid 3007, and polyethylene glycol 1607 with an average molecular weight of 6250 were uniformly dissolved in deionized water in a polymerization vessel with a stainless steel interior and a capacity of 801<g. A monomer solution of

After this solution was sufficiently deoxidized by nitrogen purge, 2,2'-azobis-2-
Add 8.0y of amidinopropane hydrochloride,
Polymerization was carried out under adiabatic conditions. Polymerization was completed in 180 minutes,
The temperature of the polymer reached a maximum of 95°C due to the heat of polymerization. After polymerization is complete, remove the top plate of the polymerization container and place the container body into one
The polymer was taken out by inverting it 80 times, but in this case, the stickiness of the polymer gel to the polymerization container was not a problem. One batch of this polymer gel weighs 40 kg when dried.
The string-like gel aggregate obtained by passing through an extrusion disintegrator with an internal cutter having a perforated plate with a hole diameter of 3.2 m1 at the tip at a ratio of I did it.

The drying conditions were a drying drum rotation speed of 4.5 RPM, a hot air inlet speed of 0.6 m/sec, a hot air temperature of 60° C., and a drying time of 300 minutes. During the drying process, the crushed polymer has a diameter of several M77!
The particles were loosened as a group of particles, and dried while flowing well in the drying drum, and finally, dried pellets in the form of flakes, which were very easy to handle*2, were obtained. The dried pellets were pulverized using a pulverizer to obtain a powdered polymer. This powdery polymer is soluble in water, and when an aqueous solution dissolved at a concentration of 1% was measured using a B-type viscometer at 20°C and 6RPM, the viscosity was 4800c. p. The water content in the powder was 7.9%. Comparative Example 1 A monomer solution containing only polyethylene glycol from the monomer solution composition of Example 1 was polymerized under the same conditions as Example 1.

The polymer gel thus obtained had higher stickiness than that of Example 1, and was sticky and very difficult to handle.

After crushing this gel, it was run in a dryer under the same conditions as in Example 1. Since the adhesiveness of the crushed gel was remarkable, most of the crushed gel adhered to each other and solidified, or stuck to the inner surface of the dryer drum. Good dry pellets could not be obtained due to adhesion of the polymer, and there were also major operational inconveniences, such as requiring a lot of effort to remove the polymer adhering to the interior of the dryer.

Example 2 Using a 1.51 experimental polymerization vessel, monomer solutions (each 10007) having the composition shown in Table 1 were sufficiently deoxidized by nitrogen purge, and then heated at 30°C for 2 hours.・2'-azobis-2-amidinopropane hydrochloride 0.1
7 was added, and polymerization was carried out under adiabatic conditions.

The obtained polymer gel was crushed using a small extrusion crusher equipped with a perforated plate with a hole diameter of 4 mm and an internal cutter, and spread on a synthetic resin net in a shelf-type hot air dryer for 15 minutes at 60°C.
The gel was dried for a period of time, and the mutual adhesion of the gel during the process from disintegration to drying was evaluated.

Example 3 Adiabatic polymerization was carried out in the same polymerization vessel as in Example 2 under the monomer solution composition and polymerization conditions shown in Table 2.

These polymerized gels were crushed and dried in the same manner as in Example 2, and the mutual adhesion of the gels was evaluated, and the results shown in Table 2 were obtained.

Claims (1)

[Claims] 1. A water-soluble acrylamide with improved adhesiveness characterized by subjecting a high concentration of monomer to aqueous solution polymerization in the presence of polyethylene glycol to obtain a water-soluble acrylamide polymer or copolymer in the form of a hydrogel. Method for producing polymers.