JPS6316402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing fine particles of acrylamide polymer with a small amount of residual acrylamide. More specifically, when the acrylamide polymer gel obtained by polymerization is made into fine particles, an alkaline substance and/or a compound having or generating active hydrogen is present in the inside of the fine particles. The present invention relates to a method for producing acrylamide-based polymer fine particles in which the residual amount of acrylamide is reduced by mixing the acrylamide-based polymer into a fine particulate material.

[Prior Art] Conventionally, acrylamide homopolymers, copolymers mainly composed of acrylamide with other polymerizable monomers, or alkaline hydrolysates thereof have been used as paper strength agents and thickeners. It is widely used as a soil conditioner, crude oil recovery agent, wastewater treatment agent, etc.

Methods for producing these water-soluble acrylamide polymers include bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization, but it is important to produce polymers with essentially high molecular weight. Therefore, an aqueous solution polymerization method is usually adopted in many cases.

In order to obtain a polymer with a very high molecular weight and good water solubility by aqueous solution polymerization, it is necessary to prevent crosslinking during the polymerization reaction stage, and the polymerization must be carried out at a relatively low concentration. There is a need.

However, in recent years, economic efficiency such as transportation costs and storage costs has become more important, and powder products have become more mainstream than liquid products. When powdering the obtained polymer, a large amount of water must be volatilized and drying must be carried out, which has the disadvantage that the utility cost for powdering increases.

In order to eliminate such drawbacks, research has been conducted to reduce utility costs in the powdering stage by polymerizing at as high a monomer concentration as possible, and numerous patent applications have been filed.

However, vinyl monomers such as acrylamide and acrylic acid inherently have a very strong tendency to crosslink and become three-dimensional. For example, in the case of anionic or nonionic compounds, the amount of
The polymerization must be carried out while maintaining the concentration at a relatively low concentration (the same applies hereafter).

When acrylamide or a monomer solution mainly consisting of acrylamide at the above concentration is polymerized, a hard or highly elastic gel-like material with no fluidity is obtained. Therefore, for example, if you try to volatilize the water contained in a mass or sheet of gel polymer without mechanically crushing it, you will have to leave it under high temperature for a very long time. As a result, the molecular weight of the high-molecular-weight polymer that has been painstakingly produced decreases, and crosslinking of the polymer due to thermal changes is promoted, resulting in a significant decrease in commercial value. Therefore, generally obtained polymer gel lumps or sheets are crushed by some mechanical means into small agglomerated particles, and then
A method of removing water by drying by heating is used.

Usually, an extrusion molding machine such as a meat grinder is used as a method to mechanically crush the polymer gel obtained by polymerization, but in this case, the efficiency of the machine decreases due to friction and molecular breakage occurs. Therefore, the present inventors have already filed a patent application dated November 6, 1982 (title of invention "Method for crushing water-soluble polymer gel", hereinafter referred to as Application A). An improved crushing method is proposed. In addition, a patent application dated November 6, 1982 (invention title "Fine particles of water-soluble polymer gel" The patent proposes the method described in the specification (hereinafter referred to as "Application B").

By using these technologies, a process is established in which the polymer gel obtained by polymerization is continuously crushed and finely granulated, and then dried and sized to reduce the particle size. It has now been possible to develop a process for obtaining acrylamide-based polymers with a well-defined high molecular weight.

[Problems to be Solved by the Invention] The present invention provides that the amount of acrylamide contained in the finely granulated and sized high molecular weight acrylamide polymer obtained as described above varies depending on the use. This was done to solve the problem of having too many.

[Means for Solving the Problems] The present inventors used an acrylamide polymer gel obtained by polymerizing an aqueous solution of an acrylamide monomer, and obtained a partially hydrolyzed acrylamide polymer gel. Development of polymer gel and manufacturing method,
and (or) the development of a technology for reducing the toxicity of acrylamide monomers, which is generally said to be achieved by inactivating the acrylamide monomers remaining in acrylamide polymer gels with chemical agents, and (or) acrylamide We have developed a technology to prevent the crosslinking reaction that normally occurs during the drying and powdering stages of polymer gels, and are conducting intensive studies with the aim of developing a method for producing acrylamide polymer powder with high molecular weight and good water solubility. As a result of repeated efforts, we have arrived at the present invention.

That is, in the present invention, an acrylamide polymer gel obtained by polymerizing an aqueous solution of an acrylamide monomer is crushed into an average particle size of 3 to 20 mm, and then a fixed blade and a rotary blade are used to crush the acrylamide polymer gel. Using a vertical cutting machine that has an area where the polymer gel stays and has an average residence time of 3 minutes or more,
At the stage of cutting the polymer gel into fine particles of 3 mmφ,
The present invention relates to a method for producing acrylamide-based polymer fine particles with a small residual amount of acrylamide, which is characterized by incorporating an alkaline substance and/or a compound having or generating active hydrogen.

[Example] The acrylamide monomer used in the present invention is
It contains acrylamide or 5% or more of acrylamide, and the remaining component contains other water-soluble vinyl monomers.

Specific examples of the other water-soluble vinyl monomers include water-soluble vinyl monomers such as methacrylamide, acrylic acid, methacrylic acid, vinyl sulfonic acid, acrylamide-methylpropylsulfonic acid, and itaconic acid, or those thereof. salts, (meth)
Acrylic acid dialkylaminoalkyl esters, salts or acidic salts thereof, or quaternized products thereof, dialkylaminoalkylacrylamides, salts or acidic salts thereof, or quaternized products thereof, diallylamine salts or acidic salts, diallyldialkylammonium salts, etc. Examples include, but are not limited to, diallylamines. These may be used alone together with acrylamide, or two or more of them may be mixed and used together with acrylamide.

The acrylamide monomer may include monomers that are essentially insoluble in water, such as acrylonitrile, (meth)acrylic esters, vinyl acetate, and styrene, to the extent that the resulting polymer becomes water-soluble. A hydrophobic monomer may also be blended.

There are no particular limitations on the method of polymerizing the acrylamide monomer, such as thermal polymerization using a radical polymerization initiator such as a normal persulfate or an azo initiator, or a conventional persulfate/amine or persulfate method. Common methods include a redox polymerization method using a redox polymerization initiator such as a salt/sulfite, a photopolymerization method using a photopolymerization initiator such as benzoin or benzoin alkyl ether, or a radiation polymerization method. Generally, by such a method, an aqueous solution of an acrylamide monomer of a predetermined concentration is polymerized until it no longer flows freely.

It is preferable for the polymer gel obtained using an acrylamide monomer to have as high a concentration as possible from the viewpoint of improving productivity, and also to reduce stickiness during crushing and prevent crushed materials from adhering to each other. It is also preferable from this point of view.

Generally, the nonionic or anionic polymer gel obtained by using acrylamide or acrylamide and, for example, acrylic acid has a content of 20 to 60%, preferably 30 to 45%. On the other hand, in the case of a cationic polymer gel made from acrylamide and an acid salt or quaternary salt of dialkylaminoalkyl acrylate,
%, preferably 60-70%.

In order to efficiently cut the polymer gel with a pair of roller-type cutters that rotate in a mutually interlocking direction as described in the A application specification, it is necessary to smoothly insert the polymer gel into the roller-type cutters. Therefore, the thickness of the polymer gel is preferably 2 to 30 mm, preferably 5 to 15 mm. For example, when a water-soluble vinyl monomer aqueous solution is polymerized using a dish-shaped, flat-plate-shaped, or tray-shaped container or a movable belt, it can be formed into a thin layer. The method of polymerizing in a thin layer on a movable belt is a preferred method because it can be continuous with the subsequent crushing step.

In the present invention, the polymer gel obtained as described above is crushed into average particles using a crusher as described in the specification of the A application, an embodiment of which is shown in FIGS. 4 and 5. It is crushed into pieces with a diameter of 3 to 20 mm.

If the size of the crushed material exceeds an average particle size of 20 mm, the cutting ability of the vertical cutting machine in the next step tends to decrease, and it is difficult to forcibly cut polymer gel with an average particle size exceeding 20 mm. If too much material is supplied to the vertical cutter, poor cutting will occur, and polymer gel lumps will form inside the cutter, at the same time frictional heat due to adhesion will be generated, creating an undesirable vicious cycle.

The polymer gel is fed to the crusher from above the crusher as shown in FIG. 4, for example. The supplied polymer gel is cut by roller type cutters 13 and 14 shown in FIG. 6, which is a top view of the crusher shown in FIGS. 4 and 5, and is cut into, for example, short strands. Ru.

On the surfaces of the roller type cutters 13 and 14, cutter blades are formed in a concave and convex shape so that the concave and convex portions engage with each other, as shown in FIG. 6, more specifically, FIG. 7. These interlocking roller-type cutters have, for example, the same dimensions and
Rotate in the direction of engagement at the same rotational speed. The width, depth, and height of the unevenness of the blades formed to interlock with each other are the size desired for the crushed polymer gel.
In other words, the average particle size should be determined to be 3 to 20 mm. For example, in Fig. 8, the width x ₁ is 2 to 10 mm.
Even if the depth of the concave part of the blade x ₄ is about 10 to 15 mm, and the height of the convex part of the blade x ₅ is about 10 to 15 mm, even if the concave part and the convex part are engaged at their deepest, the cut polymer will not be cut. Gap required for gel to pass (x ₃ in Figure 8)
It is usually formed with a gap of about 10 to 25 mm. The blades on the surfaces of the roller type cutters 13 and 14 are formed in such a shape, and the two roller type cutters 13 and 14 are cut using the rotating shafts 8 and 9 of the roller type cutters as shown in FIG. The polymer gel can be easily cut by rotating it as shown in Figure 4 (C-C' sectional view), biting and cutting the polymer gel supplied from above, and then feeding it downward. For example, it can be made into strands.

In order to supply the polymer gel to the roller type cutters 13 and 14, the polymer gel is continuously taken out from the other end of a movable support, for example, an endless belt, and then fed into the roller type cutters 13 and 14. By doing so, the process can be made continuous and production efficiency can be improved.

The polymer gel strand cut into short pieces, for example, by the roller cutters 13 and 14 rotating in the direction of interlocking with each other, is cut by the inner blade A of the roller cutter at the upper edge of the combs 15 and 16 shown in FIG. It is peeled off from the outer periphery of the comb, moves downward between the comb 15 and the comb 16, and reaches the position of the fixed blade 12 provided at the lower end of the comb 16. Normally, the polymer gel strands do not stick to the outer blade B of a roller type cutter. The short strand-shaped strand that reaches the position of the fixed blade 12 and comes out below the position is the rotary blade 11 provided on the outer periphery of the rotating body 10 whose rotation axis is 7 in FIGS. 4 and 5. The material is cut by the cutting force acting between the fixed blade 12 and the fixed blade 12 into small pieces, preferably rectangular pieces with an average particle size of 3 to 20 mm.

The cross-sectional shape of the short piece in the width direction is based on the machine dimensions of the roller cutters 13 and 14 after assembly,
That is, it is determined by the width x ₁ of the unevenness of the blade, the depth of engagement x ₂ , the heights x ₄ and x ₅ and the rotational speed of the roller type cutters 13 and 14 in FIG. The longitudinal shape of the short pieces (dimensions of the polymer gel to be cut into strips) is determined by the rotational speed and rotation of the rotating body 10, which rotates at a speed synchronized with the rotational speed of the roller-type cutters 13 and 14. body 10
It can be arbitrarily determined by adjusting the number of rotary blades 11 provided above (six in FIG. 5) and the slit widths of the fixed blades 12 and rotary blades 11.

Next, we will explain the cutting machine and method used to refine the polymer gel, which has been crushed into rectangular pieces with an average particle size of 3 to 20 mm. and/or a method of eliminating acrylamide in a polymer gel by incorporating a compound having or generating active hydrogen.

The key to efficiently chemically reacting the acrylamide in the acrylamide polymer gel with an alkaline substance and/or a compound that has or generates active hydrogen to eliminate the acrylamide is how to make the polymer gel uniformly fine. How to uniformly mix granulated or solid polymer gel particles with liquid or powdered alkaline substances and/or compounds having or producing active hydrogen and This is determined by whether it can be uniformly distributed to the inside of the combined gel.

As the alkaline substance used in the present invention, any alkaline chemical agent capable of hydrolyzing acrylamide can be used, such as caustic soda, caustic potash, soda ash, sodium phosphate, sodium borate, and ammonia. The alkaline substance may be used in any form such as powder, granules, flakes, liquid, or slurry, but from the viewpoint of avoiding mutual adhesion of the finely divided polymer gels, powder to It is preferable to add it in the form of a slurry. The amount added may be set according to the target hydrolysis rate.

Compounds having active hydrogen or generating active hydrogen used in the present invention include, for example, sulfites, hydrogen sulfites, mercapto group-containing compounds such as mercaptopropionic acid, thioglycolic acid, thioglycerin, thioglycol, or dimethyl Examples include amino group-containing compounds such as amine, methylethylamine, diethylamine, ammonia, dibutylamine, methylethanolamine, and diethanolamine. At least one or two or more of these compounds having active hydrogen or producing active hydrogen are selected and used. The usage form may be powder, granules, flakes, liquid, slurry, etc. The amount of the compound to be added may be the same as or slightly in excess of the stoichiometric amount of the total amount of free monomers contained in the polymer gel. Generally, addition of about 2% or less of the total amount of monomers used prior to polymerization is sufficient.

The alkaline substance and the compound having active hydrogen or generating active hydrogen may be used alone or in combination.

FIG. 1 is a schematic plan view of a vertical cutter used to reduce the crushed polymer gel used in the present invention into fine particles, and FIGS. 2 and 3 are cross-sectional views.

In Figure 1, 1 is a rotary blade, 2 and 2' are each 1
3rd and 2nd fixed blades, 3 is a pre-cutter,
4 is a screen, 5 is a rotating shaft of the rotary blade 1, 6 is a bottom surface, and 7 is a discharge hole.

The vertical cutting machine used in the present invention shown in FIG.
It has a retention area C that circumscribes the area with Do and is half-moon shaped when viewed from above and is capable of residence for 3 minutes or more, and has a drive rotation axis (axis 5 of the rotary blade in Figures 1 and 2). It points vertically upward, that is, it is a vertical point.

In Fig. 3-1, among the angular polymer gels of 3 to 20 mm to be supplied, as shown in Fig. By rotating the cutting blade at the tip of the fixed pre-cutter 3, a polymer gel having a relatively large inner diameter of 10 to 20 mm among the 3 to 20 mm angular polymer gels is crushed.

At this time, the first point of the method of the present invention is that the angular polymer gel of 3 to 20 mm is supplied (dropped) from above the axis of the shaft 5 of the rotary blade toward the shaft 5 of the rotary blade. . By doing so, the polymer gel having a coarse diameter can be selectively converged to a diameter in the range of 3 to 5 mm. The 3-20 mm angular polymer gel thus supplied is first aligned to 3-5 mm. The polymer gel cut into pieces in the range of 3 to 5 mm in this way is placed in the assembled first fixed blade 2 as shown in Figure 1 inside the main body of the vertical cutting machine.
It is inserted into a gap of 1 mm or less between the rotating rotary blade 1 and cut at the same time as it is inserted. The cut polymer gel rotates in an area a surrounded by the arc-shaped screen 4 when viewed from above, the outer peripheral edge of the rotating rotary blade 1, and the first fixed blade 2 and second fixed blade 2'. It moves along the direction in which the blade 1 rotates to the second fixed blade 2'.

The second point of the method of the present invention is that among the cut polymer gels moving within the area a, polymer gels having a diameter smaller than the pore diameter Ds of the screen 4 are scattered outward due to centrifugal force. , passes through the pores of the screen 4, is discharged from the region a to the discharge hole 7, and is separated from the polymer gel which is coarser than the pore diameter Ds of the screen.

On the other hand, among the cut polymer gels that are moving in the area a, the polymer gels with a diameter larger than the pore diameter Ds of the screen 4 are again moved to the second fixed blade 2' as shown in FIG. After being sandwiched between the rotary blades and cut, the rotary blade 1 is placed in an area b surrounded by the rotary blade 1 and the circumference drawn by an arc with the same diameter as the screen 4.
along the direction of rotation. Then, the polymer gel moving in region b is again caught in the gap between the first fixed blade 2 and the rotary blade 1 and cut, and the same cutting is repeated thereafter.

In this way, a diameter of 3 to 20 mm of the polymer gel supplied (falling) from above the axis of the rotating shaft 5 of the vertical cutting machine to the rotating shaft 5 located below the vertical cutting machine is discharged from the vertical cutting machine. It is separated into particles smaller than the hole diameter Ds of the screen 4 through the hole 7 and continuously discharged.
Desired cutting becomes possible. At this time, the pores larger than the diameter of the screen 4 are cut by the second fixed blade 2' and the rotary blade 1 as described above to reduce the diameter of the polymer gel, but the third important thing is that Thereafter, the cut polymer gel that has entered region b becomes stagnant in retention region c. Thereafter, on average at least 3
The polymer gel remaining for a minute is cut once again by the fixed blades 2, 2' and the rotary blade 1 by rotation of the rotary blade, and the above-mentioned cutting process is repeated. The average residence time exceeds at least 3 minutes, and the polymer gel staying in the residence area c is subjected to very vigorous mixing and agitation due to the centrifugal force of the rotary blade 1, as shown in Figure 3-1. As shown, by mixing an alkaline substance and/or a compound having or generating active hydrogen with the polymer gel supplied from above, the chemical reaction between the acrylamide and the acrylamide in the acrylamide polymer gel can be efficiently achieved. It becomes possible to react and eliminate acrylamide. Moreover, since mixing and stirring are performed for 3 minutes or more on average, it is useful for completing the chemical reaction for eliminating acrylamide.

As described above, the device feature of the method for eliminating unreacted residual acrylamide according to the present invention is that the drive rotation axis (axis 5 of the rotary blade in FIGS. 1 and 2) is oriented vertically upward. The mechanical structure is vertical.

The vertical cutter used in the present invention is different from typical and common commercially available crushers such as Feather mill and Futu mill, because it can maintain the average crushing residence time of the material to be crushed at 3 minutes or more. Since the combined gel is discharged with a very small number of cuts without undergoing multiple cuts, a uniform fine-grained gel is obtained. The structure of the cutting machine is characterized by adjusting the gap between the vertical fixed blades 2, 2' and the rotary blade 1 installed vertically inside the cutting machine.
The residence time of pulverization can be controlled by changing the sieve hole diameter Ds and by arranging multiple vertical cutters in series, that is, by passing through the cutters two to several times. The advantage is that it is easy to cut the polymer gel into small particle sizes, for example, 1 mmφ or less. A technique for refining crushed polymer gel using a vertical cutting machine having such a structure has not been established in the past.

Because the polymer gel is finely divided in this way, alkaline substances and/or
It becomes easier to incorporate compounds having active hydrogen or generating active hydrogen, and it becomes easier to eliminate acrylamide contained in the polymer.
In addition, the polymer gel is made into fine particles, but it can be kept within the necessary particle size range, and ultra-fine particles (particles that fly as dust when dried after passing through 200 meshes and create an undesirable working atmosphere) The occurrence of can be suppressed.

For example, in the first step, if you cut using a cutting machine equipped with a 3mmφ screen, it will be approximately 3mm
A finely divided polymer gel having a uniform diameter of φ can be obtained. Then, in the second step, the particles are finely granulated using a cutting machine equipped with a 2 mmφ screen, and in the third step, the particles are refined using a cutting machine equipped with a 1 mmφ screen, resulting in fine grains that are uniform in diameter of approximately 1 mmφ or less and have a rounded appearance. Not only can granulated particles be obtained, but the generation of undesirable ultrafine particles (passing 200 meshes) can be almost completely prevented. By selecting a screen suitable for the target particle size in this way, the target particle size can be obtained.

In addition, when the manufacturing method of the present invention is adopted, almost no dust is generated during the step of refining the polymer gel, which is essentially in a wet state, and the particle size is uniform and the particle size distribution is close to monodisperse. available. Moreover, the alkaline substance and the compound having or producing active hydrogen can be easily dispersed in the finely divided polymer gel, and the chemical reaction can be efficiently promoted.

When crushing the polymer gel to make it fine particles, in order to increase the cutting efficiency and prevent the resulting fragmented polymer gel and the finely divided polymer gel from re-adhering, It is preferable to keep the temperature of the polymer gel as low as possible during cutting.

Methods for lowering the temperature of the polymer gel include cooling sufficiently during the polymerization stage when crushing it into small pieces, and cooling the polymer gel obtained by polymerization by blowing cold air etc. before crushing it with a crusher. This can be achieved by forcible cooling, but it is generally preferred to adjust the temperature to 10 to 30°C, preferably 20°C or lower.

Furthermore, if the crushing process is cooled by passing cold air, preferably cold air at a temperature of 25° C. or lower, during the crushing process, for example, a strand is produced into short pieces, and then the strand is further cut into small pieces.
Reduces the tendency for polymer gel to become sticky due to frictional heat during cutting, drive heat from roller-type cutters, etc., and for cut pieces of polymer gel to adhere to each other and form blocks. be able to.

In addition, when the polymer gel that has been made into fine particles is further made into fine particles, the crushed polymer gel that is to be made into fine particles may be forcibly cooled in advance, as in the case where the polymer gel is made into fine particles. , cold air when refining, preferably 25
If the refining step is carried out while cooling, such as by blowing cold air at temperatures below 0.degree.

In addition, in the crushing and pulverization process, polyethylene glycol, nonionic surfactant,
By introducing anionic surfactant into a crusher or vertical cutting machine, or applying it to the surface of the polymer gel or the surface of the crushed polymer gel, it is possible to create strips of polymer gel or finely granulated polymer. It may also be used to prevent gel re-adhesion.

In carrying out the present invention, an aqueous solution of an acrylamide monomer is polymerized into a thin film on a movable support such as an endless belt to obtain a polymer gel, which is then continuously polymerized with an average particle size of 3 to 20 mm.
The average particle size is 0.3 using a vertical cutting machine.
When the grain size is reduced to about 3 mm, the entire process can be made continuous. When crushing and refining particles, blowing cold air at 25°C or below can prevent the volatilization of water from the polymer gel due to frictional heat generated during cutting, as well as particle adhesion and blocking, thereby increasing crushing efficiency. Particle granulation efficiency can be improved, as well as easier penetration and distribution of chemicals that are dispersed into the polymer gel to eliminate acrylamide. .

As described above, the present invention has been achieved by effectively utilizing the polymer gel crushing technology and granulation technology that have already been filed as applications A and B.

That is, the cutting machine described in the B application specification, as shown in FIGS. 1 to 3, is designed such that the fixed blade is composed of a rotating blade and the average residence time is at least 3 minutes or more. This is a vertical cutting machine. The polymer gel is cut into fine particles by this cutting machine, and the polymer gel is cut by the fixed blade and rotating blade while convection occurs inside the cutting machine, and a part of it is discharged. , the polymer gel stays in the cutting machine for a long time. Similarly, the chemical agent added to annihilate the acrylamide remains in the tank and comes into contact with the polymer gel particles for a long period of time.
Mixing with the polymer gel particles takes place uniformly.

Furthermore, in order to cut the polymer gel into fine particles of about 1 mm or less, a cutting machine is used in the first stage, second stage,
It is customary to cut in multiple stages, such as the third stage, and in this way, sufficient residence time is maintained, so that the chemical agent penetrates into the inside of the fine particles of polymer gel. distributed. By developing such a method, an acrylamide-based polymer having a high molecular weight, a small amount of residual acrylamide, and fine particles with good water solubility can be easily obtained.

The polymer gel, into which chemical agents are uniformly mixed and pulverized using a cutting machine, may be commercialized as it is or in the form coated with surfactants. Typically, finely divided polymer gels are
For example, it is dried using a band dryer to form fine particles with a moisture content of 10% or less.

The polyacrylamide is hydrolyzed by an alkaline substance before drying the finely granulated polymer gel in which the chemical agent used in the present invention is uniformly mixed. The hydrolysis reaction of the finely divided polymer gel was accomplished in a surprisingly short time (approximately 10-15 minutes) compared to approximately 60-90 minutes using, for example, 5 mm square polymer gels. This is an effective method.

Compounds that have or generate active hydrogen are
When it comes into contact with the finely divided polymer gel and permeates inside, it reacts stoichiometrically with the remaining acrylamide, completing the addition reaction to the double bond. Of course, increasing the temperature in the dryer helps to further accelerate the reaction to completion.

In this way, fine particles of acrylamide polymer with a small amount of residual acrylamide are produced.

Next, the manufacturing method of the present invention will be explained based on Examples.

Example 1 A polymerization device with a jacket (length 200 mm, width 300 mm, height
A 500mm square container (without top lid) was installed. Acrylamide with dissolved oxygen sufficiently removed using nitrogen gas in a deoxidizing tank (cylindrical type with a capacity of 1)
150 g, 38 g of acrylic acid and 20 g of caustic soda dissolved in 275 g of deionized water,
After adding 5 ml of 5% potassium persulfate aqueous solution and 5 ml of 5% sozo sulfite aqueous solution and continuing deoxidizing with nitrogen gas for several minutes, the mixture was introduced into the polymerization apparatus installed in a room sealed with nitrogen gas, Polymerization was started. Water at 25°C was passed through the jacket. Polymerization started after about 10 minutes, and the aqueous monomer solution gradually thickened. When 15 minutes had passed after the start of polymerization, the monomer aqueous solution was in a state of gradual fluidity.

Approximately 2 hours after the start of polymerization, the polymer became a hard gel.

The polymer gel was approximately 8 mm thick.

The obtained polymer gel was crushed using a crusher as shown in Figs. 4 to 6, and the width of the unevenness of the roller type cutter shown in Figs. 10mm, depth of engagement 7mm, roller type cutter surface speed 10.5cm/min, rotary blade rotation speed 20-100r/min and crush at 20°C, approximately 3 x 8 x 3 mm. cut into corners. Thereafter, the 3 x 8 x 3 mm angular polymer gel was fed from above into a vertical cutting machine as shown in Figures 1 to 3, and was allowed to fall. The material was cut using a vertical cutting machine equipped with a 3 mmφ screen, then a 2 mmφ screen was used as a second stage, and a vertical cutting machine equipped with a 1 mmφ screen was used as a third stage.

In addition, when refining, use flaked caustic soda 20
A slurry prepared by dissolving and suspending 3 g of sodium sulfite and 3 g of sodium sulfite in 20 g of water was gradually added to the first stage cutter. Moreover, the relaxation of the average residence time in the tank of the cutting machine in the first to third stages was about 21 minutes.

The finely divided polymer gel obtained had particles with a diameter of about 1 mm.

When the obtained polymer gel with a diameter of about 1 mm was dried with hot air at 80°C, a powder with a moisture content of 10% or less and a uniform particle size was obtained in about 30 minutes. The powder has an intrinsic viscosity of 25 dl/
g, about 20 mol% of polymerized acrylamide
was hydrolyzed. Furthermore, the amount of acrylamide contained in the powder was 0.038%. By the way,
Acrylamide was present in the polymer gel before addition of flake caustic soda and sodium sulfite.
It contained 1.8% (per solid content).

When the powder was dissolved in water to make a 0.1% aqueous solution,
No water-soluble substances were observed.

Example 2 An endless belt made of stainless steel with a width of 450 mm and an effective length of 3000 mm was attached with a vapor-deposited ethylene tetrafluoride-ethylene copolymer film with aluminum on the back side, and hot to cold water was applied to the endless belt from below. A movable support for polymerization was installed in a chamber completely filled with nitrogen gas, and was operated at a low speed of 100 mm/min. Sprayed with water. In addition, a low-pressure mercury lamp is installed as an ultraviolet irradiation source on the top of the movable support to control the intensity of ultraviolet rays.
It was set to 50W/ ^m2 .

Concentration adjusted to PH8 with 10% caustic soda aqueous solution
Approximately 40 g of a 40% aqueous solution of acrylamide was fully degassed with nitrogen gas and metered onto the running belt from one end at a rate of 13.5/hr.

Additionally, from a temporary storage tank (capacity 5) with a stirrer installed above the belt, 30ml/30ml of benzoin isopropylethyl 5% methanol solution was added as a polymerization initiator.
The aqueous monomer solution and the polymerization initiator were supplied onto the belt while being uniformly mixed, and polymerization was carried out by irradiation with ultraviolet rays.

Under the above conditions, the time during which the aqueous monomer solution was subjected to polymerization on the belt was 30 minutes, and the layer of the aqueous monomer solution during polymerization was about 5 mm.

Thirty minutes after the start of supplying the monomer aqueous solution, a sheet-like polymer gel with a thickness of about 5 mm was obtained from the other end of the endless belt. The obtained copolymer gel was in a state where it could be easily peeled off from the belt surface by hand, and continuous polymerization for about 3 hours was possible.

The temperature of the obtained polymer gel was about 20°C.

The polymer gel sheet continuously obtained from the other end of the endless belt is transferred to a crusher as shown in FIGS. 4 to 6 above roller-type cutters 13 and 14 rotating in the interlocking direction as shown in FIG. Continuously supplied from the crusher, crushed, approximately 3× from the crusher outlet
A 5 x 3 mm square polymer gel was obtained.

Thereafter, as shown in FIG. 3, the angular polymer gel was fed into a vertical machine as shown in FIGS. 1 and 2 from vertically above the shaft 5 of the rotary blade.

At this time, a screen with a hole diameter of about 3 mm was set on the cutting machine. Approximately 15℃ from above the cutting machine
Then, cutting was carried out using a cutting machine equipped with a 2 mm φ screen and then a 1 mm φ screen to obtain a finely divided polymer gel having a size of about 1 mm φ or less. In addition, when making the particles into fine particles, 2 kg of flaked caustic soda, 0.27 kg of sodium sulfite, and 2.27 kg of pure water were prepared in advance.
A slurry with a specific gravity of approximately 1.51 was fed into the first stage cutting machine at a rate of 1.0/hr. Moreover, the total average residence time in the tank of the cutting machines from the first stage to the third stage was about 30 minutes.

When the obtained finely divided polymer gel having a diameter of about 1 mm or less was dried at 80° C. in a belt-type ventilation dryer, a powder with a moisture content of less than 10% was obtained in about 20 minutes.

The intrinsic viscosity of the obtained powder was 24 dl/g, approximately 20 mol% of the polymerized acrylamide was hydrolyzed, and the acrylamide contained in the powder was 0.047%. Moreover, no water-insoluble substances were observed in the 0.1% aqueous solution.

Example 3 Instead of the 40% concentration acrylamide aqueous solution used in Example 2, 20 kg of 50% acrylamide aqueous solution,
A polymer gel was produced in the same manner as in Example 2, except that a 60% monomer aqueous solution with a specific gravity of 1.11%, consisting of 25 kg of 80% N,N,N-trimethylaminoethyl methacrylate chloride aqueous solution and 5 kg of pure water, was used. Thereafter, the obtained polymer gel sheet with a thickness of 5.0 mm is placed above the roller-type cutters 13 and 14 that rotate in the interlocking direction as shown in FIG. 5 of the crusher shown in FIGS. 4 to 6. A angular polymer gel of approximately 3 x 5 x 5 mm was obtained.

Then, while blowing cold air at about 15℃, about 3mmφ
Using a cutting machine as shown in FIGS. 1 and 2 equipped with a screen, the angular polymer gel is fed from vertically above the shaft 5 of the rotary blade as shown in FIG. Subsequently, it was cut through a cutter equipped with a screen of about 2 mmφ and a screen of about 1 mmφ in this order to obtain a polymer gel finely divided into particles of about 1 mmφ.

In addition, when refining the particles, 30% sodium bisulfite slurry was fed into the first stage cutting machine at a rate of 0.12/hr. Moreover, the total average residence time in the tank of the cutting machines from the first stage to the third stage was about 30 minutes.

When the resulting finely divided polymer gel with a diameter of about 1 mm was dried at 80° C. in a hot air dryer, a powder with a moisture content of 10% or less was obtained in about 20 minutes.

The resulting powder is 0.1% water-soluble, contains no water-insoluble substances, has an intrinsic viscosity of 8.5 dl/g, and has a cationization rate.
It was 40 mol%. Further, the amount of acrylamide contained in the powder was 0.065%.

[Effects of the Invention] According to the method of the present invention, the process of continuously crushing and pulverizing the polymer gel can be performed. The polymer gel can be pulverized into extremely fine particles, and the fine particles of the polymer gel can be granulated to each other. As a result, the drying efficiency of the next process can be greatly increased.
100 mesh pass) is extremely small, which can solve the problem of dust generation and dusting, etc. There is almost no decrease in the degree of polymerization or molecular weight during crushing and crushing of polymer gel (conventional methods reduce the molecular weight). The toxicity of acrylic monomers can be eliminated by inactivating the free monomers present in water-soluble polymer gels with chemical agents (agents that contain or generate active hydrogen). When the gel microparticles come into contact with the chemical agent and permeate inside, it stoichiometrically reacts with the free monomers present, completing the addition reaction to the double bond and reducing the remaining monomer). You can get the effect.

[Brief explanation of the drawing]

Figures 1 to 3-1 are explanatory diagrams of an embodiment of the vertical cutting machine used in the present invention, Figures 3-2 are explanatory diagrams showing the structure of the screen in three dimensions, and Figures 4 to 6 The figure is an explanatory diagram of an embodiment of the crusher for producing crushed pieces used in the present invention, FIG. 7 is an explanatory diagram of the engaging portion of the roller type cutter, and FIG. 8 is an explanation of the details of the engaging portion. FIG. (Main symbols in the drawing), 1: rotating blade, 2: first fixed blade, 2': second fixed blade, C: retention area.

Claims (1)

[Claims] 1. An acrylamide-based polymer gel obtained by polymerizing an aqueous solution of an acrylamide-based monomer is crushed to an average particle size of 3 to 20 mm, and is then crushed using a fixed blade and a rotating blade. At the stage of cutting the polymer gel into fine particles of 0.3 to 3 mmφ using a vertical cutting machine that has a region where the polymer gel to be processed remains and has an average residence time of 3 minutes or more, an alkaline substance and (or) A method for producing acrylamide-based polymer fine particles with a small residual amount of acrylamide, characterized by incorporating a compound having active hydrogen or generating active hydrogen. 2. The manufacturing method according to claim 1, wherein the acrylamide polymer fine particles are dried. 3. The manufacturing method according to claim 1 or 2, which involves continuously crushing and/or cutting while passing cold air at 25° C. or lower. 4. Claims 1, 2, or 3 in which the compound having active hydrogen or generating active hydrogen is one or more of sulfites, hydrogen sulfites, mercapto group-containing compounds, and amino group-containing compounds.
Manufacturing method described in section.