JPS6017283B2 - Drying method for acrylamide polymer particles - Google Patents

Description

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

As a method for producing an acrylamide polymer, for example, 1
A method of polymerizing an aqueous acrylamide solution of 0 to 3% by weight in the presence of a catalyst has been carried out industrially, but the amount of polymer obtained by this method is small.

Therefore, the polymer usually needs to be granulated using a pongee granulator and then dried. A common drying method is hot air drying, in which the polymer particles are usually fed onto a wire-mesh endless belt conveyor and continuously dried with hot air on the belt. However, particles of acrylamide polymers have adhesive properties and also have the property of shrinking when dried. Therefore, when particles are supplied in a layered manner onto a drying belt and dried, both ends of the particle layer are warped during drying, making it impossible to dry uniformly. In view of the above circumstances, the present inventors investigated various methods for drying acrylamide-based polymer particles, and found that granular The present invention was completed after discovering that warping of the material layer can be prevented.

That is, the gist of the present invention is that when continuously hot air drying hydrogel acrylamide polymer particles having a water content of 65 to 9% by weight, a belt is formed of stainless steel plates at both ends on a wire mesh. The method is characterized in that the polymer particles are supplied onto a moving belt having a side wall so that the particles adhere to the inside of the side wall and have a substantially uniform thickness between both side walls, and then dried with hot air on the belt. The present invention relates to a method for drying acrylamide polymer particles.

To explain the present invention in detail, the acrylamide-based polymers to which the present invention applies include acrylamide homopolymers, acrylamide and acrylic acid, methacrylic acid, sodium acrylate, vinyl acetate, acrylonitrile,
Examples include polymers with dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc.

In the case of a copolymer, it is better to contain acrylamide in an amount of 30 mol% or more, preferably 50 mol% or more.
Polymerization is usually carried out by adding a peroxide such as potassium persulfate or ammonium persulfate to a 10 to 35% by weight monomer aqueous solution.
A known polymerization initiator such as an azo compound such as asobis(2-amidinobroban) hydrochloride or a redox catalyst in combination of a peroxide and a reducing component is added,
It is carried out at a temperature of 0,000. The polymer thus obtained is a mass consisting of a rubbery gel with a water content of 65-9% by weight. This polymer is then granulated in a granulator to a particle size of 1 to 8 skins/machine, preferably 2 to 5 skins/machine. Granulation can be carried out using a commonly used meat grinder, although various methods can be applied. Before drying, the granulated polymer may be hydrolyzed by contacting with an alkali such as caustic soda, caustic potash, sodium carbonate, or potassium carbonate, if necessary. Next, the polymer particles are dried with hot air on a moving belt. Usually, the method of the present invention is applied to a so-called band drying device that continuously dries the polymer particles by passing the polymer particles through a hot air zone using an endless belt conveyor. It is preferable to apply.

In the present invention, the belt is made of a wire mesh material such as wire mesh or punched metal, and side walls made of stainless steel plates are provided at both ends of the belt. The stainless steel plate of the side wall preferably has a contact angle with water of 40 to 70 degrees. Stainless steel plates are installed almost at right angles to the belt surface, but if a too long stainless steel plate is installed, it will be difficult to rotate at the end of the endless belt conveyor, so a stainless steel plate with a length of 10 to 50 skins is usually installed. A method of arranging them is preferable. The height of the side wall may be slightly higher than the height at which the polymer particles are loaded, and is usually 8 to 15 mm. Continuously feeding polymer particles onto a belt as described above, but with the polymer particles adhering to the inside of said sidewall;
Supply so that the thickness is uniform between both side walls.

If the degree of adhesion of the polymer particles to the inside of the side wall is insufficient, the ends of the polymer particle layer will warp up during drying, which is not preferable. The temperature during drying of the present invention is usually 120°C.
The temperature is preferably 40 to 100 q○, and drying at too high a temperature will cause thermal deterioration of the polymer, and drying at too low a temperature will not result in sufficient drying.

The polymer particles obtained by drying are in the form of particles, and are usually
This is pulverized into granules using a pulverizer, and further dried if necessary to produce a product. As described above, according to the present invention, the ends of the polymer particle layer are not warped during drying, and uniform drying can be performed. Further, the polymer particles adhering to the side wall made of the stainless steel plate are easily peeled off after drying, and a flat layered material is preferably supplied to the next pulverizer. 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 Nitrogen gas was blown into a 25% acrylamide aqueous solution to degas the dissolved oxygen, and then 0.2% by weight (based on acrylamide) of 2,2-azobis(2-amidinoproban) hydrochloride was added as a radical generator. Polymerization was started.

After one hour, a water-containing rubbery gel was obtained. This water-containing rubbery gel was prepared using a screw with a screw diameter of 40 m and a length of 160 m'.
Number of pitches: 4t, number of revolutions: 8. p. m, exit die hole diameter 2.4
A granulated material with a particle size of 2.5 Kite's skin was molded using a meat grinder with 4 rotating blades.

After loosening the obtained granules, a wire mesh endless conveyor with a band width of 150 degrees and a length of 1,700 degrees was provided with stainless steel plates having a height of 10 degrees and a contact angle with water of 60 degrees as side walls at both ends of the band. It was dried using a drying device.

The polymer particles were uniformly supplied to the drying device so that the particles were 5 cm high between both side walls. The drying temperature at this time was 70 qo, and the drying time was 3 minutes. The thus obtained dried pulverized granules were flat and layered.

In addition, when the water content of the granules at the center and end portions of the belt was measured, the results are shown in Table 1. That is, from this result, it can be seen that in the drying method of the present invention, particles are uniformly dried over the entire surface of the belt. Comparative Example In the example, drying was carried out in the same manner without providing the side wall made of stainless steel plate.

Claims (1)

[Claims] 1. For continuous hot air drying of hydrous gel-like acrylamide polymer particles having a water content of 65 to 90% by weight, the belt is shaped like a wire mesh and has side walls formed of stainless steel plates at both ends of the belt. An acrylamide system characterized by supplying polymer particles onto a moving belt so that the particles adhere to the inside of the side wall and have a substantially uniform thickness between both side walls, and drying with hot air on the belt. Method for drying polymer particles.