JPS5815481B2 - Method for producing water-soluble polymer gel - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for producing a water-soluble polymer gel.
The purpose is to facilitate the production of a water-soluble polymer gel by using a polymerizer material with good peelability.

A highly concentrated water-containing polymer containing a high degree of polymerization such as acrylate, methacrylate or acrylamide is usually obtained as a gel having rubber elasticity.

The polymer shrinks slightly as the polymerization progresses, but when the polymerization is completed, it completely adheres to the wall of the polymerization vessel.

As the adhesion area increases, it becomes increasingly difficult to separate the gel-like polymer from the wall of the polymerization vessel, and as the adhesion area increases, it becomes almost impossible to separate the gel body from the polymerization vessel.

The present inventors conducted tests on various materials in this regard, and found that peeling was extremely easy only when using metal coated with either nylon or fluorine-containing resin, and developed the present invention. It was completed.

Usually, these polymer gels and the wall of the polymerization vessel are in close contact with each other without any gaps, but the adhesive strength between the gel and the wall of the vessel is weak.

Therefore, in a small polymerization vessel with a small adhesion area, there is no problem because the gel and vessel wall can easily be peeled off.

However, when producing polymer gels on a large scale industrially, this adhesion poses extremely difficult equipment problems.

That is, when a polymer forms a gel with no fluidity, the thermal conductivity of the gel is low, so the heat of polymerization accumulates inside the gel, resulting in a high temperature, resulting in a decrease in the degree of polymerization or a decrease in the polymerization rate.

In order to avoid this, it is essential to increase the heat transfer area of the polymerization vessel, and usually the heat transfer area reaches 20 to 40 square meters per unit cubic meter of polymer gel.

In a polymerization vessel with such a wall area, if the polymer and the vessel wall are slightly adhered, it is extremely difficult to separate them, and if the polymer is forcibly removed with strong force, the rubber-elastic polymer will break the base material. A part of the product remains on the wall of the container, causing a serious hindrance to repeated operations, making it unusable as an industrial device.

In order to solve this problem, the present inventors conducted extensive studies and found that a polymerization apparatus using a metal plate coated with nylon or fluorine-containing resin as the wall material of the polymerization vessel has a unique feature. It has been found that the polymer gel can be easily peeled off, and that the polymerization operation can be carried out without any problems when reusing it.

The present inventors have conducted tests on many materials on an industrial scale, and the effects of the present invention are extremely remarkable, as shown in the Examples.

The reason why nylon and fluorine-containing resin have particularly good releasability is not necessarily clear, but both produce an extremely thin layer of low polymerization polymer on the surface of the polymer gel that adheres to it, and this creates a layer of low polymerization between the gel and the vessel wall. The small amount of oxygen adsorbed or occluded on the resin surface, acting as a lubricant, inhibits the polymerization of the 7-mer at the vessel wall interface, resulting in an excellent peeling effect. Presumed.

On the other hand, in wall materials where a large amount of oxygen exists at the vessel wall interface, such as polyethylene powder coating lining with closed microbubbles, the polymerization rate of the monomer near the vessel wall is slow, resulting in a high degree of stickiness over a thickness of 2 to 3 mm. It is difficult to remove the gel because it remains as a liquid, and if the wall material is a stainless steel plate, the monomer polymerizes at the wall interface as well, forming a highly polymerized polymer, which is thought to cause strong adhesion.
Furthermore, when a silicone resin coating is baked onto a stainless steel plate, the coating itself tends to peel off, making repeated use difficult.

The method of the present invention is useful for the polymerization of water-soluble monomers such as acrylic acid, methacrylic acid, their alkali metal or ammonium salts, and acrylamide, which are essential for use as flocculants, thickeners, sedimentation agents, etc. It is.

In these polymerizations, the polymer temperature during polymerization is preferably low, but if it is extremely low, the polymerization rate will decrease, so it is preferably about 50° C. or higher.

As the monomer concentration increases, the allowable upper limit temperature also increases, but in the case of polymerizing an aqueous monomer solution with a concentration of 35%, it is generally preferred to be 85° C. or lower, and a polymer with a high degree of polymerization cannot be obtained above this temperature.

Therefore, it is essential that the polymerization vessel material has good heat transfer properties as well as peelability.

Examples and comparative examples will be described below.

Example and Comparative Example Two replaceable sheets 1 whose interior formed by assembling was formed with a coating of the following material (including cases without coating)
Assemble a 50mm thick and 60mm wide iron frame with a side plate of 000mm x 1000mm x 100mm and a seven-piece inlet to form a hollow, flat 1000mm x 1000mm x 100mm.
A box of O was constructed, and one end of the iron frame was fixed vertically so that the injection port was at the top.

After filling the interior with high-purity N2 gas, the aqueous solution 8 containing 20% sodium acrylate containing 50 ppm of ammonium persulfate and 15% acrylamide was sufficiently deoxidized in advance.
0 kg was charged, and during polymerization, cooling water at 20° C. was sprayed over the entire surface of both side plates, and after polymerization was completed, one side plate was separated from the polymer by input.

The peeling situation at this time is shown below. The lining thickness of (S) was 0.03 mm.

Among the peelability evaluation results, × indicates that peeling was impossible by one person's manual labor.

△ indicates that manual peeling is possible, but natural peeling does not occur when the polymerization vessel is tilted at 45°.

(2) indicates that the polymer peels off naturally simply by tilting the polymerization vessel at 45 degrees.

Claims (1)

[Claims] 1. A water-soluble polymer characterized in that the aqueous solution polymerization of the water-soluble monomer is carried out using a polymerization apparatus in which the contact portion with the charged water-soluble monomer aqueous solution is made of nylon or a metal coated with a fluorine-containing resin. Method of manufacturing gel.