JP6024091B2 - Method for dissolving powdered water-soluble polymer compound - Google Patents

Description

The present invention relates to a method for dissolving a powdery water-soluble polymer compound.

When a powdery water-soluble polymer compound such as a polymer flocculant is dissolved in water or an aqueous solution, the water or aqueous solution is generally poured into the water surface in which the water or the aqueous solution has been stirred in advance. A method is used in which a powdery water-soluble polymer is added to an aqueous solution after being mixed little by little.

  However, when a powdery polymer compound is directly added to the water surface of water or an aqueous solution, there is a problem that spatter is generated. Here, when the powdered water-soluble polymer compound is added to the liquid all at once, the portion where the powdered water-soluble polymer compound is in contact with the liquid immediately contains the liquid and starts to swell and becomes tacky. Tinged. By becoming sticky, the powders easily adhere to each other, and the powdery water-soluble polymer compound not touching the liquid is wrapped and becomes a lump. This lump is called a step child and remains as an undissolved substance. In addition, in the method of adding water or an aqueous solution to the water surface so as not to generate a step, and adding the powdered water-soluble polymer to the water or aqueous solution in small amounts, the powdered water-soluble polymer is added in small amounts. There is also a problem that it takes a long time to add the solution and the dissolution time becomes long.

  Further, when the pumping capacity is close to the limit and the amount of the water-soluble polymer compound to be added must be further increased, the concentration of the water-soluble polymer compound may be increased. Alternatively, it may be necessary to add the powdery water-soluble compound without diluting so as not to lower the concentration of the lysate contained in the aqueous solution before adding the powdery water-soluble compound. In that case, when a powdery water-soluble polymer compound is added directly to the water surface in the aqueous solution, the powder does not get caught in the aqueous solution, and most of the powder drifts, and the powder adheres to each other, generating a large lump as a clump. Resulting in. In order to solve this problem, it is necessary to increase the concentration by increasing the number of stirring rotations or increasing the dissolution time as compared with normal dissolution to swell and dissolve the generated step by step.

  For example, when used as an internal additive for papermaking and a dewatering agent for sludge, the prescribed viscosity cannot be obtained due to the generation of the successor, and the desired drainage and dewaterability cannot be exhibited. In order to compensate for this, the amount used will be increased to achieve the target performance, and in order to reduce the number of generated step children, the work of crushing the mass of step members, or stirring for a long time, etc. It is not economical because it must be done.

  In a stirring device in which water or an aqueous solution is generally used, for example, as shown in FIG. 3, in a stirring device 20 in which a rotary blade 23 is disposed around a rotary shaft 22 installed vertically in a stirring tank 21, the rotary blade 23 is a flat blade as shown in the figure, or in the case of a turbine blade or a propeller, the horizontal water flow becomes strong and the vertical flow of the water flow is small. Therefore, when a powdery water-soluble polymer compound is added The powder is difficult to be caught in the fluid, and the powder drifts on the liquid surface, and the added powders adhere to each other to form a lump, which causes the lump to grow and become a step child. In order to reduce the generation of the step child, it is possible to stir at high speed and to add a small amount of powdered water-soluble polymer compound over a long period of time. And there is a problem that the viscosity of the obtained aqueous solution is lowered, and there is a need for a solution.

  However, as for the method and apparatus for dissolving the powdered water-soluble polymer compound in water or in a solution without generating a step, it has not been proposed yet, but recently, As a stirring device suitable for stirring a high-viscosity fluid, many combinations of inclined blades and plate-like paddle blades have been proposed.

  For example, as a stirring device that can stir and mix fluids in a wide range of viscosity from low viscosity fluids to high viscosity fluids, a plate-shaped paddle is installed at the bottom of the rotating shaft, and the upper inclined blades An upper inclined wing that is installed to be inclined upward from the rotation axis, and a lower inclined wing that is installed to be inclined downward from the rotation axis, and the lower portion of the upper inclined wing and the upper portion of the lower inclined wing are: There has been proposed a stirring device provided with stirring blades that are arranged to overlap each other in the axial direction (Patent Document 1). Moreover, the stirring apparatus which improved this stirring apparatus further is also proposed (patent document 2).

  In addition, a plate paddle is placed at the bottom of the rotating shaft and the fluid is raised at the top as a stirring device with increased shearing force to break up and disperse the solvent and powder lumps added to the fluid. A stirrer blade provided with two sets of inclined blades that combine a wall-side inclined paddle inclined in a direction to cause a fluid and a shaft-inclined inclined paddle inclined in a direction to lower the fluid, and a baffle plate is provided in the agitation tank. An installed stirring device has been proposed (Patent Document 3).

  Furthermore, as a stirrer suitable for mixing other fluids and powders in a viscous fluid or controlling the temperature of the reaction product in an exothermic polymerization reaction of a fluid raw material, it is installed vertically in a stirring tank. A stirring device that stirs a high-viscosity fluid by arranging a plurality of rotating blades around a rotating shaft, and a plate-like inclined blade inclined with respect to the rotating direction of the rotating shaft is disposed above the rotating shaft, A plate-shaped paddle parallel to the rotation axis is disposed below the rotation axis, and the outer peripheral end of the inclined blade is on the circumference centered on the rotation axis when viewed from above the rotation axis. A stirring device having a vertical plate is proposed at the outer peripheral end of the upper half of the inclined blade (Patent Document 4).

Japanese Patent Laid-Open No. 9-75699 JP 2000-210549 A JP 2002-273188 A JP 2010-58027 A

The object of the present invention is to suppress the generation of a step when a powdered water-soluble polymer compound is added in advance to a water or aqueous solution stirring tank, so that the powdered polymer compound can be dissolved in a short time. It is to provide a dissolution method for suppressing a decrease in viscosity of a polymer aqueous solution under subsequent stirring.

As a result of intensive studies on a method of dispersing or dissolving a powdery water-soluble polymer compound in a liquid, the present invention is basically the same as the stirring device proposed in Patent Document 4 among the many stirring devices proposed. In this method, a stirrer having the same configuration is used, and a dissolving method by a stirring action is repeated in which the fluid is collected and lowered at the central part of the stirring tank and then lifted so as to spread to the peripheral part of the stirring tank. When it was adopted, the knowledge that the above object could be achieved was obtained, and the present invention was completed.

That is, the gist of the present invention is a method of adding a powdery water-soluble polymer compound to stirred water or an aqueous solution and dissolving the powdered water-soluble polymer compound around a rotating shaft installed vertically in a stirring tank. A stirrer for agitating the liquid by arranging a rotary blade, wherein a plate-like inclined blade inclined with respect to a rotation direction of the rotary shaft is arranged at an upper portion of the rotary shaft, and is rotated at a lower portion of the rotary shaft. A plate-shaped paddle parallel to the shaft is disposed, and the outer peripheral end of the inclined blade is on a circumference centered on the rotating shaft when viewed from above the rotating shaft, and the upper half of the inclined blade is At the outer peripheral end, using a stirrer equipped with a vertical plate, the powdered water-soluble polymer compound is stirred in a range where the stirring speed of the stirring blade maximum diameter portion is in the range of peripheral speed 0.1 to 0.7 m / s. Water directly added to the surface of an aqueous solution containing dissolved water or a water-soluble polymer compound dissolved therein It consists in dissolution process of sexual polymer compound.

  According to the present invention, when a powdery water-soluble polymer compound is dissolved in water or an aqueous solution, generation of a step is suppressed and the powder can be dissolved in a short time. Further, when the powdered water-soluble polymer compound is dissolved in the aqueous solution, no additional water is required, and the concentration of the components contained in the aqueous solution before the addition can be maintained. Furthermore, the viscosity reduction of the polymer aqueous solution under stirring after dissolution can be suppressed and dissolved.

FIG. 1 is a schematic view of a stirring device used in the present invention, where (a) is a front view and (b) is a plan view. 2A and 2B are schematic views of the inclined blades in the stirring device used in the present invention, where FIG. 2A is a plan view of the inclined blades, FIG. 2B is an example of inclined blades with a vertical plate hanging downward, and FIG. An example of inclined wings with plates attached to both upper and lower sides, (d) shows another example of inclined wings with substantially triangular vertical plates attached to both upper and lower sides, and (e) shows an example with two sets of inclined wings. FIG. 3 is a schematic view (front view) of a stirring device used in a comparative example described later.

  Hereinafter, the present invention will be described in detail.

  First, an example of a stirring device used as a dissolving device in the present invention will be described. The stirring device described below is substantially the same as the device shown in the embodiment of Patent Document 4.

  FIG. 1 is a schematic view showing an example of a typical stirring device. (A) is a front view, (b) is a plan view. In addition, the place where the stirring apparatus 1 in FIG. 1 is installed in the stirring tank 2 is described. The stirring tank 2 is a vertical stirring tank which is a cylindrical container, and the stirring device 1 is inserted from the upper part thereof.

  In the stirring device 1, a plate-like paddle 4 that is a plate-like paddle is fixed to the lower part of the rotating shaft 3. The plate-like paddle 4 is a plate parallel to the rotating shaft 3 and is arranged extending in the radial direction of the rotating shaft. The vicinity of the tip of the plate-shaped paddle 4 is bent or curved so as to recede at a receding angle of 30 to 45 degrees with respect to the rotational direction of the rotating shaft 3 while being parallel to the rotating shaft 3 as indicated by reference numeral 4a. It is preferable. By doing in this way, it can suppress that the fluid under stirring is caught in the back side of plate-like paddle 4 (back side of plate-like paddle 4 at the time of rotation). The plate-shaped paddle 4 may be a plurality. In that case, the plate-like paddles 4 are preferably arranged at equal intervals.

  The ratio of the radius of the stirring tank 2 and the distance from the center of the rotating shaft 3 to the outer peripheral end of the plate-shaped paddle 4 is preferably 1.1 to 1.5. The outer peripheral edge of the plate-shaped paddle 4 becomes larger as it is closer to the side wall of the agitation tank 2, and the ability to transfer the downward flow to the peripheral part of the agitation tank 2 increases. A passage for ascending and ascending is necessary. In order to secure this passage, it is preferable that the ratio of the radius of the stirring tank 2 and the distance from the center of the rotating shaft 3 to the outer peripheral end of the plate-shaped paddle 4 is 1.1 to 1.5.

  An inclined wing 5 and an inclined wing 6 having the same shape are disposed on the upper part of the plate-shaped paddle 4. The inclined wing 5 and the inclined wing 6 are respectively fixed to the rotary shaft 3 at the center of the inner side, and the inclined wing 5 and the inclined wing 6 have the rotary shaft 3 as a center of rotation. Located on both sides. In addition, it is preferable that the number of the inclined blades is two or more. The inclined blades are arranged around the rotation shaft 3 at equal intervals around the rotation shaft 3, and the rotation shaft 3 is evenly distributed when the rotation shaft 3 is rotated. It is preferable to apply a centrifugal force. The inclined wing 5 and the inclined wing 6 are fixed at the same height position of the rotary shaft 3 by a connecting jig 9. Each of the inclined blades 5 and the inclined blades 6 are inclined with respect to the rotation direction of the rotation shaft. In other words, the inclined wing 5 and the inclined wing 6 are higher in the portion in front of the rotation direction than the connection point with the rotating shaft 3 (may be lower, but in this case, the rotating shaft is reversed. The normal rotation is when rotating.) The inclination angle of the inclined blade 5 and the inclined blade 6 is approximately 45 degrees with respect to the rotation direction (horizontal plane), and is usually preferably set within a range of 20 to 70 degrees. By doing in this way, the effect which the inclined wing | blade 5 and the inclined wing | blade 6 descend | fall a fluid below is exhibited most.

  When the stirring tank is higher than the inner diameter, multi-stage inclined blades may be attached in the vertical direction. When a multistage inclined wing is attached, the inclined wing above the lowest inclined wing is referred to as an additional inclined wing. It is preferable that a vertical plate is also installed on the additional inclined blades, and the lower end of the vertical plate has a height equal to or higher than a horizontal plane that passes through the coupling portion with the rotation axis of each additional inclined blade. The additional inclined blade with the vertical plate attached is only the upper half surface (front of the rotation direction from the joint with the rotating shaft), and it can be added to the upper part of the normal inclined blade (the inclined blade arranged at the bottom). Good. Furthermore, in the case of a stirring tank having a high height ratio, the same one as a normal inclined blade may be added.

  In the stirring tank 2, the inner diameter of the stirring tank 2 is 1.3 to 1.8 times the diameter of the arc formed by the outer peripheral ends of the inclined blades 5 and 6 of the stirring device installed inside. The diameter of the agitation tank 2 may theoretically be 1.4 times (21/2 times), but the cross-sectional area of the rotating shaft 3, the inclined blades 5 and 6, the vertical plates 7 and 8, and the agitation Considering the cross-sectional area occupied by the boundary layer that tends to stay in the vicinity of the inner wall of the tank, it was set to 1.3 to 1.8 times. In this embodiment, the inner diameter of the stirring tank is 1.54 times. Thereby, the cross-sectional area of the region occupied by the downflow and the cross-sectional area of the region occupied by the upflow are substantially equal, and the flow rates of the downflow and the upflow can be made the same.

  The inner diameter of the stirring tank 2 is preferably 1.1 to 1.5 times the circle formed by the outer peripheral edge when the plate-shaped paddle 4 is rotated. In this embodiment, the inner diameter of the stirring tank 2 is 1.4 times. In this way, an upward flow is effectively formed with respect to the driving force for rotation of the rotary shaft 3.

  As can be seen from the plan view shown in FIG. 1B, the inclined blades 5 and the inclined blades 6 are on the circumference centering on the rotation shaft 3. That is, when viewed from a plan view, the outer shapes of the inclined blades 5 and the inclined blades 6 are circular when the rotary shaft 3 is rotating. When the inclined wing 5 and the inclined wing 6 are viewed as parts, as shown in FIG. 2 (a), the shape is obtained by chamfering an acute angle portion by dividing into two equal parts so as to cut the major axis side of the elliptical flat plate. do it.

  In the stirring device 1, the inclined blades 5 and 6 are provided with vertical plates 7 and 8 at the outer peripheral ends, respectively. The vertical plates 7 and 8 are plates that hang vertically from the outer peripheral end on the upper half side of the inclined blades 5 and 6. Since the vertical plates 7 and 8 are disposed at the outer peripheral ends of the inclined blades 5 and 6, they are part of the same circle as the outer peripheral ends of the inclined blades 5 and 6 in the plan view 1b. . Moreover, in front view 1 (a), it is a triangle. The vertical plates 7, 8 are preferably at the same height as the horizontal plane passing through the center of the inclined blades 5, 6 or above the vertical plates 7, 8. 2A, the right half of the figure is the upper part of the inclined wing, and the vertical end to the intersection of the outer peripheral edge of the inclined wing and the line inclined rightward from the center by an angle τ. What is necessary is just to arrange | position a board. The angle τ is 0 to 60 degrees, preferably 0 to 45 degrees. The shape of the vertical plates 7 and 8 is a part of a cylinder. However, if the vertical plates 7 and 8 are flattened by being removed from the inclined blades 5 and 6, the shape of the vertical plates is only on the lower side as shown in FIG. For example, it is almost a triangle.

  As shown in FIGS. 2 (b) to 2 (e), the vertical plates 7 and 8 may be formed on any of the lower side, the upper side, and the upper and lower sides from the outer peripheral end of the inclined blades 5 and 6. . Although not shown in the drawing, a vertical plate may be formed only on the upper side from the outer peripheral end of the inclined blades 5 and 6. The inclined blades 5 and 6 have a function of pressing down the fluid to generate a downward flow on the lower side and attracting the fluid to generate a downward flow on the upper side. At this time, since the centrifugal force in the radial direction due to the rotation simultaneously acts on the fluid, it is an important role of the vertical plates 7 and 8 to suppress the diffusion of the fluid in the radial direction due to the centrifugal force. Further, an important role of the vertical plates 7 and 8 is to apply a shearing force to the fluid that rises while the outer peripheral surfaces of the rotating vertical plates 7 and 8 turn. Further, the shape of the vertical plates 7 and 8 when flattened may be any shape such as a trapezoid or a parallelogram, as shown in FIGS. 2 (b) to 2 (e). Further, the corners may be chamfered to reduce the fluid flow resistance.

  The lower ends of the vertical plates 7 and 8 are slightly above the same height as the central portions of the inclined blades 5 and 6. If the vertical plates 7 and 8 are too short, the downward flow of the inclined blades 5 and 6 cannot be sufficiently prevented from protruding to the outside. If the vertical plates 7 and 8 are too long below the center, the lower half surfaces of the inclined blades 5 and 6 ( As a result of obstructing the suction of fluid from the outer periphery to the center of the rotation axis on the blade surface of the rear half of the rotation direction of the inclined blade coupled with the rotation shaft, the flow from the upper half surface of the inclined blade to the lower half surface is increased. Therefore, it is preferable to set the length to the same height as the central part of the inclined blades 5 and 6.

  When the stirring tank is relatively long, it can be a stirring device provided with two or more inclined blades. FIG.2 (e) is a stirring apparatus provided with two sets of inclined blades. In FIG. 2 (e), the lower inclined wing is an inclined wing having the same vertical plate as shown in FIG. 2 (c), and the upper inclined wing is that shown in FIG. 2 (d). An inclined wing with the same vertical plate. In FIG. 2 (e), two sets of inclined blades 5 and 6 and inclined blades 5 'and 6' protrude from the rotary shaft 3 in the same direction, but the inclined blades 5 and 6 and the inclined blade 5 ' , 6 'may be shifted in the rotational direction. For example, the downward flow may be efficiently formed by shifting the inclined blades 5 and 6 and the inclined blades 5 ′ and 6 ′ by 90 degrees or 30 degrees in the rotation direction.

  Next, a method for dissolving the powdered water-soluble polymer compound using the stirring device will be described. In the present invention, “dissolution” is defined as a powdery water-soluble polymer compound dispersed in a liquid to form a homogeneous system.

<Operation conditions of the stirring device>
The stirring speed is usually 3 m / s to 0.1 m / s, preferably 1 m / s to 0.45 m as the peripheral speed of the stirring blade maximum diameter part (usually the maximum diameter part of the paddle) from the viewpoint of preventing generation of the step. / S. If it exceeds 3 m / s, scattering of the polymer powder under stirring and a decrease in molecular weight due to shearing of the dissolved polymer compound occur, and if it is less than 0.1 m / s, generation of the step cannot be suppressed. The temperature of the liquid in which the water-soluble polymer compound is dispersed or dissolved is usually 5 to 50 ° C, preferably 20 to 30 ° C. By setting the temperature of the liquid to 5 ° C. or more, generation of a step can be suppressed and the dissolution time of the water-soluble polymer compound can be shortened. Moreover, the viscosity fall after a water-soluble high molecular compound melt | dissolves can be prevented by making the temperature of a liquid into 50 degrees C or less.

<Composition of water-soluble polymer compound>
The water-soluble polymer compound used in the present invention is a general powdery water-soluble polymer, and is not particularly limited as long as it is a polymer compound that dissolves in a liquid. It is suitable for dissolving the following ionic (cationic, amphoteric, anionic) and nonionic high molecular weight compounds.

  Examples of the cationic polymer include methyl chloride of dialkylaminoalkyl (meth) acrylate, quaternary salt of benzyl chloride, tertiary salt of sulfuric acid, methyl chloride or benzyl quaternary salt of dialkylaminoalkyl (meth) acrylamide, sulfuric acid Examples thereof include homopolymers such as tertiary salts, and copolymers of these cationic monomers and nonionic monomers such as (meth) acrylamide.

  Examples of the amphoteric copolymer include a copolymer of the above cationic monomer, a nonionic monomer, and a (meth) acrylate.

  Nonionic polymers include homopolymers such as (meth) acrylamide, vinylformamide, vinylacetamide and the like.

  Examples of the anionic polymer include a homopolymer of (meth) acrylic acid or (meth) acrylate, a copolymer of (meth) acrylic acid or a salt thereof and a nonionic monomer, and the like.

  In addition, hydrophobic monomers such as vinyl acetate, acrylonitrile, and (meth) acrylic acid esters may be copolymerized as long as water solubility is not impaired. Two or more cationic monomers, anionic monomers and nonionic monomers may be copolymerized as appropriate.

  The method for dissolving the powdered water-soluble polymer compound according to the present invention can be applied to various applications, but in particular, solid-liquid separation for wastewater treatment, dissolution of a polymer flocculant used for sludge dehydration, and papermaking process. It is effective for dissolving internal additives.

<Form of water-soluble polymer compound>
The water-soluble polymer compound used in the present invention is in a powder form. The particle diameter of 70% by mass or more is usually 50 μm to 2.0 mm. From the viewpoint of suppression of the step, the lower limit of the particle diameter is preferably 150 μm, and from the viewpoint of the dissolution rate, the upper limit of the particle diameter is more preferably 1.5 mm.

<Type of water or aqueous solution>
Examples of the water used in the present invention include ion exchange water, pure water, tap water, industrial water, rain water, sea water, lake water, river water, ground water, well water, agricultural water, reused water, reprocessed water, sludge, and sewage. And drainage.

  In addition, an aqueous solution in which an inorganic compound, an organic compound, and / or the water-soluble polymer compound is dissolved in advance using water as a solvent can be used. Examples of the inorganic compound include sodium sulfate and sodium nitrate. The viscosity of the aqueous solution is usually 10,000 mPa · s or less, preferably 5000 mPa · s or less, as a value measured with a B-type viscometer. If it is higher than 10000 mPa · s, it will be difficult to prevent generation of the step. The amount of water or aqueous solution that is required in advance before adding the powdered water-soluble polymer compound is not particularly limited, but is preferably at least as long as the stirring blade is immersed in water or the aqueous solution, so that stirring can be performed.

<Method for adding water-soluble polymer compound>
In the dissolution method of the present invention, a water-soluble polymer compound can be directly added to the water surface at a rate of 10 to 1000 g / min with respect to 1 L of water or an aqueous solution. If the addition rate is less than 10 g / min, the conventional stirring blade can be used, and the effect of the stirring method of the present invention cannot be sufficiently exhibited. In the case where the addition rate is greater than 1000 g / min, generation of a step occurs. The method for adding the powdered water-soluble polymer compound is not particularly limited, and a method of dropping powder by tilting the bag or an automatic powder feeder can be used.

  The lower limit concentration of the water-soluble polymer compound in the aqueous solution after dissolution is usually 0.1 g / L, preferably 1 g / L. If it is less than 0.1 g / L, a large tank volume is required due to the low concentration, and the installation location is limited. Although depending on the type and molecular weight of the water-soluble polymer compound to be used, when the addition concentration is larger than 100 g / L, the water-soluble polymer compound has a high dissolution viscosity, resulting in a high viscosity. As a result, the stirring motor may not be able to rotate. Furthermore, there is a possibility that liquid feeding with a pump to another tank may be difficult.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not limited by the following description, unless the summary is exceeded. In the following examples and comparative examples, “%” means “% by mass” unless otherwise specified.

  The types of water-soluble polymer compounds used in the following dissolution tests and the evaluation criteria for the amount of generation of passages are as follows.

<Anionic polymer compound>
Acrylamide-acrylic acid sodium salt copolymer (powder, “AP517C” manufactured by Dianitics)

<Cationic polymer compound>
Dimethylaminoethyl acrylate quaternary salt-acrylamide copolymer (powder, “KP1227H” manufactured by Dianitricks)
Dimethylaminoethyl methacrylate quaternary salt polymer (powder, “CHHP295” manufactured by Dianitics)

<Evaluation criteria for the generation amount of stepchild>
Thirty minutes after the addition of the powdered water-soluble polymer compound, the generation amount of the step per 1 L of water or aqueous solution was visually observed and evaluated according to the following criteria.

◎: generation amount of step generation is 0 ○: generation amount of step generation is 1 to 3 △: generation amount of step generation is 4 to 10 ×: generation amount of step generation is 11 or more

Example 1:
1L of ion-exchanged water is charged into a stirring tank (inner diameter of about 100 mm, height of 120 mm, effective capacity of 1 L) at a water temperature of 25 ° C., and the rotation speed is obtained using a stirring apparatus 1 (manufactured by Flotech Co., Ltd.) as shown in FIG. Stir at 150 rpm. In this stirring apparatus 1, as stirring blades, inclined blades 5 and 6 having an outer diameter of 65 mm and an inclination angle of 45 ° are provided on the upper stage, and paddle blades 4 having an outer diameter of 90 mm are provided on the lower stage (so that the tip is retracted by about 30 °). Refracted). The inclined blades 5 and 6 are provided with vertical plates 7 and 8 each having a length of 65 mm.

  While stirring under the condition of a peripheral speed of a stirring blade having a maximum diameter of 90 mm: 0.707 m / s, AP517C: 2 g was added directly to the water surface in 1 second, and stirring was continued and dissolved. AP517C instantly dispersed in the aqueous solution when it touched the water surface. The evaluation results of the generation amount of the step are shown in Table 1, and the generation amount of the step after the stirring for 30 minutes was 0, and it was confirmed that the generation was visually observed.

Examples 2-9:
As shown in Table 1, the same operation as in Example 1 was performed except that the type and concentration of the aqueous solution charged into the stirring tank and the type and concentration of the powdered water-soluble polymer compound were changed. All were instantly dispersed in the aqueous solution. As shown in Table 1, it was confirmed that the amount of generation of the step after the stirring for 30 minutes was 0, and it was visually dissolved.

Comparative Examples 1-9:
As shown in Table 1, the kind and concentration of water to be charged into the stirring tank and the kind and concentration of the powdered water-soluble polymer compound were changed, and the stirring tank 21 shown in FIG. 2 (inner diameter of about 100 mm, height of 120 mm, effective 1L) and a stirring device 20 (consisting of a rotating shaft 22 and a stirring blade 23, the stirring blade 23 having a plate blade of two stages, an interval between the upper and lower blades of 44 mm, a blade width of 75 mm, and a blade height of 18 mm). The same operation as in Example 1 was performed. In either case, a step was not instantaneously dispersed in the aqueous solution, and as shown in Table 1, the step was left even after 30 minutes of stirring. Stirring was continued for another 30 minutes, but none of the stepchildren disappeared.

1: Stirring device 2: Stirring tank 3: Rotating shaft 4: Plate-shaped paddle 5: Inclined blade 6: Inclined blade 7: Vertical plate 8: Vertical plate 9: Connecting jig 10: Baffle plate 20: Stirring device 21: Stirring vessel 22: Rotating shaft 23: Stirring blade

Claims (2)

In the method of adding and dissolving a powdered water-soluble polymer compound in stirred water or an aqueous solution, the liquid is obtained by disposing a plurality of rotating blades around a rotating shaft installed vertically in a stirring tank. The plate-shaped paddle parallel to the rotation axis is disposed below the rotation shaft, and a plate-shaped inclined blade inclined with respect to the rotation direction of the rotation shaft is disposed on the rotation shaft. The outer peripheral end of the inclined wing is on a circumference centered on the rotating shaft when viewed from above the rotating shaft, and a vertical plate is provided on the outer peripheral end of the upper half of the inclined wing. Water or a water-soluble polymer in which a powdery water-soluble polymer compound is stirred with a stirring speed of a stirring blade having a maximum diameter portion in a range of a peripheral speed of 0.1 to 0.7 m / s using a stirring device provided A method for dissolving a water-soluble polymer compound, wherein the compound is directly added to the water surface of an aqueous solution in which the compound is dissolved The method for dissolving a water-soluble polymer compound according to claim 1, wherein the powdered water-soluble polymer compound is directly added to the water surface at a rate of 10 to 1000 g / min.