JPH0218713B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of forming a powdered polymer flocculant into a granular hydrogel that is easy to handle. Prior Art Most of the conventionally commercially available anionic and cationic flocculants are in powder form and have the following drawbacks. Flying of fine powder The fine powder contained in powdered products, especially the fine powder of 200 mesh powder, tends to fly when preparing for use, and it adheres to the face of the worker and removes moisture from the mucous membranes of the eyes, lips, nose, etc. It absorbs and becomes a jelly-like thick liquid due to its high absorption and wettability, which often causes health problems such as adhesion to the inner wall of the trachea. In addition, the flight of fine powder will form a thin layer of powder product on the floor of the workplace during use, but if the powder product mixes with water leakage in the workplace, it will become slippery and there is a risk of falling accidents for workers. The sex was also hot. Powder products are usually used after being dissolved in water, but powder products are generally prone to forming lumps. , which makes powder products difficult to dissolve in water, and in order to uniformly dissolve powder products in water in a short time of 30 minutes or less, special equipment is required, such as Japanese Patent Publication No. 58-42204 and Japanese Patent Application Laid-open No. 58-42204. It was believed that the equipment described in Publication No. 79525 was required. As described above, although conventional powder products have excellent efficacy based on their water solubility and high molecular weight, they have many problems in terms of handling, and there is a need for efficient solutions to these problems. It will be done. As a solution, flocculant manufacturers are trying to
At present, we are trying to sort out the mesh pass through a sieve and commercialize only relatively coarse particles. Attempts have also been made to develop flocculants that can be easily dissolved without forming lumps, but Due to the problem of caking, a definitive product has not yet been obtained. As a new method, Japanese Patent Application No. 59-23356 describes
After crushing the polymer gel obtained by polymerizing an aqueous solution of a water-soluble vinyl monomer, vertical cutting is performed such that the average crushing residence time is at least 3 minutes or more.
Disclosed is a method for producing powder by further refining the powder without generating fine powder. In this method, a hydrated polymer gel is crushed and dried while maintaining the hydrated state to obtain granules that do not contain fine particles and have a sharp particle size distribution, but special equipment is required. Therefore, large capital investment is required. Purpose of the Invention The purpose of the present invention is to provide a method for converting a powdered polymer flocculant into a fine-grained hydrogel that is easily soluble in water and has good workability without the generation of fine powder or mutual adhesion. do. Structure of the Invention The method of the present invention comprises a powdered polymer flocculant and 0.5% of at least one water-soluble substance selected from polyethylene glycol, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.
~10% by weight aqueous solution at a weight ratio of 1:0.13~3.0
Continuously feed into the stirring tank at a ratio of 20
It is characterized by producing a granular hydrogel containing ~80% water by weight. That is, in the present invention, a powdered polymer flocculant is forcibly mixed with an aqueous solution of a specific water-soluble substance in a stirring tank, and instantaneously absorbs the aqueous solution to form a granular hydrogel. The particle size of the hydrogel can be arbitrarily selected by changing the particle size of the powdered polymer flocculant and the amount of the aqueous solution used together with it. A hydrogel with a large particle size can be obtained by increasing the particle size of the powdered polymer flocculant, and a hydrogel with a large particle size can also be obtained by increasing the amount of the aqueous solution. . For example, average particle size
By using a 0.5 mm powdered polymer flocculant and changing the amount of the aqueous solution used, a hydrogel having a particle size of 0.6 to 7.0 mm can be easily produced. Also, the amount of water-soluble substances contained in the above aqueous solution is
0.5 to 10% by weight, but if this is too low,
The produced hydrogels adhere to each other and become lumpy with stirring, making it impossible to obtain the desired product. On the other hand, if the amount of the water-soluble substance is too large, it is not only uneconomical, but also the presence of the water-soluble substance may cause harmful effects during use, which is not preferable.
The concentration of water-soluble substances in the aqueous solution used in the present invention is generally preferably 1 to 5% by weight. Furthermore, if the water content of the gel body is less than 20% by weight, it becomes a powder and it is impossible to obtain the hydrogel body which is the object of the present invention, and if it exceeds 80 weight%, it becomes a stable hydrogel body with excellent solubility. cannot be formed. In addition, the hydrogel body produced in the present invention is
It is desirable to remove the gel from the stirring tank as quickly as possible; if the residence time is too long, there is a risk that the hydrogels will adhere to each other. Generally, it is desirable that the residence time of the hydrogel is 1 to 10 seconds. Although the present invention can be effectively applied to all general powder polymer flocculants, representative powder polymer flocculants include polyacrylamide, polyacrylamide partial hydrolyzate, polyacrylamide, and others. Examples of vinyl monomers copolymerized with polyacrylamide include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and dimethylaminohydroxypropyl acrylate. , dimethylaminohydroxypropyl methacrylate, dimethylaminoethyl acrylamide, etc., cationic vinyl monomers converted into quaternary ammonium salts with a quaternizing agent such as alkyl halides and dialkyl sulfates, acrylonitrile, methacrylamide, etc. Examples include nonionic monomers such as nitrile, methyl acrylate, ethyl acrylate, and methacrylamide, and anionic monomers such as acrylic acid, methacrylic acid, and salts thereof. In addition, the water-soluble substances contained in the aqueous solution used in combination with the powdered polymer flocculant have an average molecular weight of 300~
It is preferable to use polyethylene glycol having an average molecular weight of 50,000, particularly from 1,000 to 10,000, or polyoxyethylene sorbitan fatty acid ester having an HLB of 10 or more. Next, the present invention will be explained in more detail with reference to Examples, in which a stirring device shown in the drawings was used. This stirring device has a sluice-type discharge port 9 having a sluice-type discharge upper plate 4 and a lower plate 5 on the side of a cylindrical container 1, and a vertical drive motor 7 is installed in the lower center of the cylindrical container 1. There is a drive shaft 8 which is rotated by a rotor, and rotary blades 2 and 3 of two types, long and short, are attached above and below to this drive shaft 8, and an aqueous solution storage tank 6 is provided above the stirring tank 1. An aqueous solution such as polyethylene glycol is introduced from the aqueous solution storage tank 6 into the cylindrical container 1 through a supply pipe 10. The introduction speed of the aqueous solution is adjusted by a valve 11, and the powder flocculant is directly introduced into the cylindrical container 1. Example (1) Cylindrical container 1 with a diameter of 50 cm and a height of 60 cm shown in the drawing
While rotating the rotor blades 2 and 3 at a speed of 400 r/m, a
A polyacrylamide flocculant whose intrinsic viscosity [η] measured at °C is 24.2 (with a hydrolysis rate of 20 mol%,
Average particle size 0.55mm including 1% of 200 mesh passes
powder) is supplied from the top of the cylindrical container 1 at a rate of 20.1 Kg/hr, and at the same time the molecular weight is supplied from the aqueous solution storage tank 4.
6000 polyethylene glycol 5% aqueous solution
It was supplied at a rate of 16.3Kg/hr. This method was carried out continuously for 23 minutes, but the polyacrylamide flocculant added absorbed a 5% aqueous solution of polyethylene glycol and swelled in a short period of time, with an average particle size of 0.75 mm.
A granular hydrogel was continuously obtained (yield:
14.1Kg). This hydrogel body has a solid content of 50.6% (water content of 49.4%).
%), and contains an appropriate amount of moisture, so it has a moist appearance and does not generate dust, and is easy to handle with no caking phenomenon between particles. The solubility was almost as good as that of polyacrylamide. Experiments similar to those described above were conducted by changing the addition rate of the polyethylene glycol aqueous solution as shown in the table, and gel bodies with different water contents were obtained. The results of measuring the dissolution rate of various gel bodies in water are displayed together with the measured value (No. 1) of the untreated flocculant.

[Table] As is clear from the table, No. 2 according to the present invention
While the hydrogels No. 4 to 4 were completely dissolved in about 20 minutes, the powdered product No. 1 required more than 30 minutes to dissolve. It should be noted that the No. 1 powdered product temporarily caused a "sticky" phenomenon during dissolution, and it took time for uniform dissolution. Example [2] A method similar to Example [1] was carried out using polyethylene glycols having different molecular weights. The properties of each product (hydrogel body) are shown in the table.

[Table] In both products, the hydrogels did not adhere to each other and could be easily loosened by hand. No solidification (caking) phenomenon was observed. Example [3] HLB= instead of polyethylene glycol
Hydrogel bodies with various water contents were obtained in the same manner as in Example [1] except that polyoxyethylene sorbitan fatty acid ester (monourate) of 16.7 was used. The properties of the obtained hydrogel are shown in the table.
All of the products had good solubility in water, mutual adhesion, and were easy to handle without solidification.

[Table] Effects of the Invention In the present invention, a powdered polymer flocculant can be easily prepared into a granular hydrogel that is easily soluble in water. The water-containing gel obtained by the present invention does not become a fine powder and deteriorate the environment of the workplace, and it is extremely highly soluble and can be dissolved uniformly in water in a short time of about 20 minutes without causing "stickiness" even at room temperature. It is easy to handle and does not cause mutual adhesion (caking) of hydrogel bodies.

[Brief explanation of drawings]

The drawing is a sectional view of a stirring device used in an example of the present invention. 1... Cylindrical container, 2, 3... Rotating blade, 4...
Aqueous solution storage tank, 5... Sluice gate type outlet plate, 6... Sluice gate type outlet plate, 7... Vertical drive motor, 8... Drive shaft, 9... Discharge port, 10... Supply pipe, 11...
valve.

Claims (1)

[Claims] 1 Powdered polymer flocculant and a 0.5 to 10% aqueous solution of at least one water-soluble substance selected from polyethylene glycol, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester at a weight ratio of 1:0.13 to 3.0. At the same time, the powder flocculant is continuously supplied to a stirring tank and mixed by stirring to produce a granular hydrogel containing 20 to 80% by weight of water. Method.