JP2009001641A - Method for producing acrylic polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an acrylic polymer, which mixes a polymerization initiator with an acrylic monomer and polymerizing the mixed solution without using a stirring blade. <P>SOLUTION: An aqueous solution of an acrylic monomer such as a deoxidized acrylamide etc. , is mixed with a polymerization initiator, for example, by using the flow energy of the aqueous solution of the acrylic monomer and the mixed solution is polymerized in a stationary state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to the production of acrylic polymers.

  Examples of a method for producing an acrylic polymer such as polyacrylamide used for a paper strength enhancer and a polymer flocculant include, for example, an aqueous solution of an acrylic monomer such as acrylamide containing a peroxide bond such as persulfate. A method of polymerizing in the presence of a polymerization initiator such as an initiator, a redox initiator obtained by combining this with a sulfite, or an azo initiator is known.

  In the polymerization, in order to ensure the uniformity of the produced polymer, it is usually preferable that the aqueous solution of the acrylic monomer and the polymerization initiator are sufficiently stirred and mixed prior to the polymerization.

  In this stirring and mixing, for example, an acrylic monomer aqueous solution 3 is put into a closed polymerization tank 1 as shown in FIG. 3A and aerated with nitrogen gas supplied from an aeration tube 4. While stirring by rotating 2, the above polymerization initiator is added to perform polymerization. Such a method is described in Patent Document 1, for example.

JP-A-8-109220

  However, especially when acrylamide or an acrylic monomer mainly composed of this polymer is polymerized to form an acrylic polymer, a hydrous gel with less fluidity is produced, so that it adheres to the stirring blade 2 or takes the stirring blade 2 into the gel. It will become. For this reason, it is difficult to disassemble the polymerization tank 1 after polymerization and extract the stirring blade 2 from the hydrogel as shown in FIG. 3B, and in some cases, the stirring blade 2 may be damaged. . Even if it could be taken out, it had to be washed because the acrylic polymer was adhered to the stirring blade 2. For this reason, the structure of the polymerization tank becomes complicated, and it has been difficult to automate the process and perform efficient production.

  Therefore, the present invention provides an easily polymerized acrylic polymer production method that can polymerize acrylic monomers such as acrylamide without immersing a stirring device such as a stirring blade in the reaction mixture. Objective.

  The present invention solves the above-mentioned problem by mixing an aqueous solution of a deoxygenated acrylic monomer and a polymerization initiator, and then carrying out the polymerization while leaving the mixed solution in a stationary state.

  If acrylic monomers such as acrylamide are sufficiently mixed with the polymerization initiator, the polymerization can proceed even if the acrylic monomer is left without being stirred by a stirrer from the outside. .

  That is, without mixing with a stirring device such as a stirring blade or an aeration tube, after mixing the aqueous solution of the acrylic monomer and the polymerization initiator in advance, the mixture is allowed to stand for polymerization. The acrylic polymer, which is a water-containing gel obtained after polymerization, does not need to include the above stirring device. Such a water-containing gel of an acrylic polymer can be easily taken out from the polymerization tank because a stirrer that does not disturb the take-out is not taken in.

  As a method of previously mixing the aqueous solution of the acrylic monomer and the polymerization initiator, there is a method of using flow energy possessed by the flow of the aqueous solution of the acrylic monomer. When the polymerization initiator is charged into a polymerization tank or the aqueous solution of the acrylic monomer is charged into the polymerization tank, the aqueous solution of the acrylic monomer has flow energy. Then, the charged polymerization initiator and the acrylic monomer aqueous solution are stirred and mixed.

  An aqueous solution of the acrylic monomer is adjusted in advance in a dissolution tank that is higher than a polymerization tank in which polymerization is performed, and charging of the aqueous solution into the polymerization tank is performed between the dissolution tank and the polymerization tank. When the height difference is used, the acrylic monomer aqueous solution is charged into the polymerization tank by changing the position energy of the height difference to kinetic energy. The kinetic energy becomes fluid energy that lasts for a while even after entering the polymerization tank. That is, by mixing the aqueous solution of the acrylic monomer and the polymerization initiator by the flow energy generated from the height difference, sufficient mixing can be performed without the need for the stirring device.

  By mixing using the difference in height as described above, the polymerization tank itself for carrying out the polymerization can be used without the stirring device, and when the one without the stirring device itself is used, the above obtained The stirrer is not taken into the acrylic polymer.

  As the acrylic monomer used in the present invention, an acrylic polymer is produced by polymerization in the above stationary state using acrylamide or a mixture of polymerizable monomers mainly composed of acrylamide. Can do.

  According to the production method of the present invention, an aqueous gel composed only of an acrylic polymer can be easily obtained without using a stirring device such as a stirring blade or an aeration tube. In addition, since it is not necessary to clean the aeration tube, which has been conventionally required, the process can be easily automated by moving the work in parallel at different times using a plurality of devices. Furthermore, since a stirring blade or the like is not taken into the aqueous gel, the work of peeling off the obtained aqueous gel from the stirring device can be omitted, and a high-quality aqueous gel can be easily obtained.

The present invention will be described in detail below.
In the present invention, when an acrylic monomer is polymerized using a polymerization initiator to produce an acrylic polymer, an aqueous solution of a deoxygenated acrylic monomer and a polymerization initiator are mixed. And a method for producing an acrylic polymer, in which the mixed liquid is allowed to stand for polymerization.

  The acrylic monomer used in the present invention is a monomer having an acrylic group such as acrylamide, acrylic acid, a water-soluble salt such as sodium salt or potassium salt of acrylic acid, or the main component of these monomers. In particular, acrylamide and a mixture of polymerizable monomers mainly composed of acrylamide have a high affinity with water, and when the polymerization proceeds, a water-containing gel is used. Monomers that easily form or mixtures thereof are preferably used. As the other monomer contained in the mixture, a compound copolymerizable with acrylamide, acrylic acid, or acrylate can be used. For example, methacrylamide, methylolacrylamide, methacrylic acid, or a sodium salt or potassium thereof. Water-soluble salts such as salts, esters, acrylonitrile, dimethylaminoethyl acrylate, ethyl chloride quaternary salt of dimethylaminoethyl methacrylate, dimethyl sulfate quaternary salt of dimethylaminoethyl methacrylate, and the like. The above mixture may contain only one kind of these compounds in addition to acrylamide, or may contain two or more kinds. The phrase “mainly composed of acrylamide” means that acrylamide is present in a maximum proportion in the monomer mixture, and preferably represents 50% by weight or more of the whole.

  The concentration of the acrylic monomer in the aqueous solution of the acrylic monomer is arbitrary depending on the application and is not particularly limited, but is preferably 10% by weight or more, and preferably 20% by weight or more. . This is because when it is less than 10% by weight, the drying time becomes longer when the resulting acrylic polymer is isolated, and the drying load becomes too large. On the other hand, it is preferably 32% by weight or less, and more preferably 30% by weight or less. If it exceeds 32% by weight, the viscosity of the liquid rises rapidly with the progress of the polymerization, so the heat removal efficiency of the reaction heat decreases, the aqueous solution boils, and the quality of the polymer obtained is lowered. May end up.

  In addition to this, in order to stably produce the acrylic polymer in a later step, to facilitate removal after production, etc., or to adjust the properties of the obtained polymer, the aqueous solution is An additive may be contained. Examples of such additives include polymerization inhibitors such as copper sulfate, manganese sulfate and thiourea, emulsifiers, antifoaming agents, mold release agents such as polyethylene glycol and urea, and heat resistance inhibitors such as methionine and mercaptobenzothiazole. Is mentioned. These additives may be contained in an aqueous solution of the acrylic monomer before being introduced into the polymerization tank, or may be added in the same manner as the polymerization initiator and mixed by self-stirring.

  In this invention, before the polymerization is started, the aqueous solution is preferably deoxygenated with an inert gas in an aeration tank. Without such aeration, the induction period until the start of polymerization becomes too long, and the reaction cannot be performed efficiently. For aeration, a general inert gas such as nitrogen can be used, and aeration can be performed by releasing a gas from a gas discharge hole provided in the aeration tank containing the aqueous solution.

  Examples of the polymerization method used in producing the acrylic polymer in the present invention include precipitation polymerization, bulk polymerization, dispersion polymerization, emulsion polymerization, and aqueous solution polymerization.

  The polymerization initiator used for polymerization in the present invention is not particularly limited. For example, at least one of an oxidizer-based initiator, a redox initiator in combination with a reducing agent, and an azo-based initiator is used. To do. Moreover, it is more preferable to contain an azo initiator in addition to the redox initiator because the reaction is further accelerated.

  Examples of the azo initiator include 2,2-azobis (2-amidinopropane) hydrochloride, azobisisobutyronitrile, 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-azobis (cyclohexanecarbonitrile) and the like. Among them, 2,2-azobis (2-amidinopropane) hydrochloride is particularly preferable because it is water-soluble and easy to use, and it is easy to obtain a high molecular weight acrylic polymer. Is preferred.

  The addition amount of the azo-based initiator is preferably 100 ppm by weight or more, and more preferably 400 ppm by weight or more with respect to the acrylic monomer. If it is less than 100 ppm by weight, polymerization may not proceed. On the other hand, it is preferably 5000 ppm by weight or less, and more preferably 1500 ppm by weight or less. If it exceeds 5000 ppm by weight, the controllability of the reaction is deteriorated, and the molecular weight of the resulting polymer is undesirably reduced.

  The above-mentioned oxidant-based initiator is usually an initiator having a peroxide bond (peroxy bond), and a radical generated by decomposition thereof acting as a polymerization initiator. As specific compounds, For example, persulfates such as ammonium persulfate and potassium persulfate, perbromate or perchlorate such as sodium perbromate, potassium perbromate, sodium perchlorate, potassium perchlorate, benzoyl peroxide, tert Organic peroxide compounds such as butyl hydroperoxide, cumene hydroperoxide, and di-tert-butyl peroxide, and peroxidic bond-containing compounds such as sodium perborate, sodium carbonate, and hydrogen peroxide can be used.

  The addition amount of the oxidizer-based initiator is preferably 1 ppm by weight or more, more preferably 3 ppm by weight or more, and more preferably 10 ppm by weight or more with respect to the acrylic monomer. Further preferred. When the addition amount is less than 1 ppm by weight, polymerization may not proceed. On the other hand, it is preferably 500 ppm by weight or less, more preferably 200 ppm by weight or less, and still more preferably 100 ppm by weight or less. If it exceeds 500 ppm by weight, the controllability of the reaction is deteriorated, and the molecular weight of the resulting acrylic polymer is lowered, which is not preferable.

  The above reducing agent acts as a redox initiator in combination with the above oxidizing agent, and specific compounds include, for example, ferrous sulfate, ferrous chloride, sodium nithionate, and nithione. Inorganic reducing agents such as ammonium acid, sodium sulfite, potassium sulfite, ammonium sulfite, potassium hydrogen sulfite, ammonium hydrogen sulfite, sodium pyrosulfite, ammonium pyrosulfite, sodium bisulfite, sodium metasulfite, sodium thiosulfate, ammonium thiosulfate, nitrite And organic reducing agents containing a reducing functional group such as a sulfinic group, a tertiary amino group, and a hydrazine group, such as toluenesulfinic acid, dimethylaniline, and phenylhydrazine. Of these, inorganic reducing agents are more desirable in terms of polymerization rate and polymerization rate in many cases.

  The amount of the reducing agent used may be appropriately adjusted according to the amount of the oxidizing agent used, but is generally about 1 to 500 ppm by weight, preferably 10 to 100 ppm by weight.

  As such a redox initiator, a redox initiator comprising a combination of tert-butyl hydroperoxide and sodium hydrogen sulfite is preferably used because the reaction can be easily controlled.

  In the polymerization, it is preferable to use the redox initiator and the azo initiator in combination as necessary. This is because the redox initiator is suitable as a low temperature polymerization initiator at the beginning, and the azo initiator is suitable for completing polymerization and polymerization at a high temperature. That is, if the polymerization is to be completed only with the redox initiator, the starting ability decreases as the polymerization proceeds, and as a result, a large amount of unreacted monomer remains. When an azo initiator is coexisted with this, the initiation ability in a high temperature state, that is, the late stage of the reaction is high, so that the polymerization can be completed to the end.

  During the polymerization reaction, it is necessary to mix these polymerization initiators with the aqueous solution of the acrylic monomer. However, when the polymerization tank for carrying out the polymerization reaction is equipped with a stirring device such as a stirring blade, the aqueous gel obtained after the polymerization takes in the stirring device, so it takes time to separate the stirring device. What it does not have is preferable. That is, it is preferable that the polymerization can be performed in a stationary state without applying external force to the mixed liquid after mixing.

  In the polymerization tank not equipped with the stirring device as described above, as a method for mixing the polymerization initiator into the aqueous solution of the acrylic monomer, as described above, in the present invention, the aqueous solution of the acrylic monomer is used. It is preferable to use a method in which the acrylic monomer aqueous solution and the polymerization initiator are mixed by the flow energy that the aqueous solution has in accordance with the charging speed when the is charged into the polymerization tank. That is, it is preferable to add a separately prepared polymerization initiator into the polymerization tank that has become fluidized by charging, or to add a polymerization initiator during or before charging.

  In addition, as another method of mixing the aqueous solution of the acrylic monomer and the polymerization initiator, there is a method in which the polymerization tank itself is vibrated and shaken from the outside, but this is sufficient. Since it is difficult to perform agitation, it is preferable to use an aqueous solution of the acrylic monomer together with introducing an aqueous solution so as to generate a flow energy using a difference in height.

As a specific method of mixing, for example, when the polymerization tank is about 1 m ³ , the total time required for dropping into the polymerization tank is preferably 5 minutes or more and 15 minutes or less. If it takes more than 15 minutes, the flow rate per hour decreases, so the kinetic energy per hour caused by the difference in height decreases, so the flow energy also decreases and the flow rate in the polymerization tank slows down. Since the initiator is not sufficiently mixed, the quality of the resulting acrylic polymer may be deteriorated. On the other hand, if it is less than 5 minutes, the addition of the additive must be rushed, and since the time for adding the aqueous solution of the acrylic monomer is short, the time for mixing with the initiator is also short, It may stop mixing.

  Further, the preferable charging time of each of the above polymerization initiators varies depending on the time required for charging the aqueous solution of the acrylic monomer, but it is 1 to 5 minutes for charging the azo initiator and 10 to 10% for the oxidizing agent. 60 seconds and 10 to 60 seconds for the reducing agent are preferred. If the charging time of the oxidizing agent and the reducing agent exceeds 60 seconds, the resulting acrylic polymer may become non-uniform. On the other hand, if it is less than 10 seconds, mixing may be insufficient.

  As shown in FIG. 1, the production apparatus for carrying out the method for producing an acrylic polymer according to the present invention is arranged above the polymerization tank 12 for carrying out the polymerization of the acrylic monomer. It is preferable to provide a dissolution tank 10 for preparing an aqueous solution by mixing water and water, and having an introduction tube 13 that can be introduced by dropping an aqueous solution containing an acrylic monomer onto the polymerization tank 12.

  In the production method according to the present invention, it is preferable to drop the aqueous solution from the dissolution tank 10 and put it into the polymerization tank 12, and to utilize the liquid flow generated at that time. It is preferable that the dissolution tank 10 exists above the surface.

  Moreover, when the aeration tank 11 provided with the aeration apparatus 11a is provided between the dissolution tank 10 and the polymerization tank 12, the solution adjusted in the dissolution tank 10 can be aerated to reduce the oxygen concentration. In this case, the aeration tank 11 is also positioned above the polymerization tank 12 in order to cause flow energy to drop from the aeration tank 11 to the polymerization tank 12. On the other hand, it is preferable that the introduction pipe 13 that connects the aeration tank 11 and the polymerization tank 12 has a valve 14 that can appropriately adjust the required dropping amount of the aqueous solution.

  Furthermore, in order to reduce the time when each equipment is not used as much as possible, a plurality of polymerization tanks are provided such as a polymerization tank 12 ′ in addition to the polymerization tank 12 as shown in FIG. It is preferable if the reaction can be carried out in parallel at different times. For example, when it takes 4 hours from the start of dropping of the aqueous solution to the polymerization tank 12 until the polymerization is completed and the aqueous gel is taken out and the next aqueous solution can be dropped, the aeration tank can be used if there is only one polymerization tank. The polymerization tank 11 is dropped into the polymerization tank for only 5 to 10 minutes in 4 hours, and an acrylic polymer aqueous gel can be obtained only once during that period. However, if there are a plurality of polymerization tanks and each time is shifted from 30 minutes to several hours and the aqueous solution and the initiator are dropped, the aerated aqueous solution is successively transferred to the polymerization tank opened after the polymerization is completed. It can be dropped, and the time when the equipment is stopped can be reduced and the production efficiency can be improved.

Moreover, it is preferable that at least the polymerization tanks 12 and 12 ′ include an initiator charging device 15 for dropping the above-described initiator separately. When using a redox initiator, it is necessary to add at least the oxidizing agent and the reducing agent separately, and when adding an azo-based initiator at the end, the timing of the addition can be specified accurately and added before that. This is because it can be clearly distinguished from the initiator. The last initiator is preferably about 100 ml of a 5% aqueous solution that is automatically injected with respect to 1 m ³ of the aqueous solution so that the reaction is easily controlled.

  On the other hand, the aeration tank 11 is designed to polymerize trace amounts of copper, manganese, etc. in order to prevent local polymerization that can occur because the acrylic monomer is easily polymerized even if there is less oxygen and no initiator. It is preferable to have an additive charging device 16 for adding an inhibitor. Such a polymerization inhibitor may be added in a process such as the dissolution tank 10 that adjusts the aqueous solution of the acrylic monomer before the aeration tank 11.

  In addition, an initiator charging device 15 may be provided so as to be connected to the introduction tube 13 so that the initiator can be mixed into the aqueous solution in the middle of the introduction tube 13. In this case, the initiator dropped together with the aqueous solution becomes a liquid flow state in the polymerization tank 12 and is mixed.

  Furthermore, you may provide the apparatus which adds said additive in the process before aeration tank 11 such as said aeration tank 11 or dissolution tank 10. FIG.

  Here, each initiator charging device 15 preferably has an introduction pipe to the polymerization tank 12 for each initiator and can be added separately. This is because mixing the initiator in advance may affect the generation of radicals.

  In the production method according to the present invention, although depending on the amount of the initiator and the aqueous solution, generally the dropping of the initiator is completed, and after the dropping of the aqueous solution is completed, the polymerization with exotherm takes 5 to 60 minutes. Polymerization proceeds and a water-based acrylic polymer gel is obtained. Further, when the polymerization aging is carried out so that the polymerization is allowed to proceed completely by standing for 0.5 hours or more and 5 hours or less, the resulting acrylic polymer has a sufficiently high molecular weight, which is preferable. .

  The acrylic polymer obtained in the polymerization tank 12 of the production apparatus according to the present invention does not include a stirring device that can come into contact with the introduced aqueous solution. The obtained resin solid can be easily taken out and crushed as it is to obtain a product. For the same reason, it is preferable not to have not only a stirrer but also a protrusion that may be taken in by the finally produced aqueous gel. Therefore, the upper lid 18 provided with the introduction pipe 13 is preferably flush with the inside, and the inner wall of the polymerization tank 12 is also flush.

  When the introduction pipe 13 and the introduction pipe 17 from the initiator introduction apparatus 15 are fixed to the upper lid 18 in advance, the obtained polymer mass is removed from the polymerization tank 12 and the upper lid 18 is closed. This is preferable because it is not necessary to remove and reconnect the inlet tube 13 and the inlet tube 17 from the upper lid 18, and the operation can be simplified. However, in that case, it is preferable that the introduction tube 13 and the introduction tube 17 are flexible tubes that can move freely so as not to obstruct the removal of the upper lid 18. In addition, the upper lid 18 is not mechanically attached and fixed to the polymerization tank 12, but has a sealing material at a position in contact with the polymerization tank 12 so that it can be adhered to the polymerization tank 12 by its own weight. The attachment and removal of the upper lid 18 is preferable because it can be simply put on and pulled up. Furthermore, it is preferable that the polymerization tank 12 has a wide-mouthed shape in which the upper part is wide and the lower part is narrowed as shown in FIG. 1 so that the aqueous gel of the acrylic polymer obtained can be easily taken out. Moreover, in order to make it easy to take out the aqueous gel, it is preferable that the polymerization tank has a rollable mechanism or can be easily connected to a rolling device.

  Unlike the conventional manufacturing method, the manufacturing method according to the present invention does not have to worry about the aqueous gel taking in a stirrer or the like, and the acrylic polymer can be obtained as one mass of the aqueous gel and adhere to other parts. Therefore, it is not necessary to clean and wash the equipment every time polymerization is performed. For this reason, since the necessary equipment can be simplified as compared with the conventional equipment and there is no place that has to depend on human hands or eyes, all of the steps can be easily automated by computer control. That is, for example, a plurality of aeration tanks and polymerization tanks are operated according to an operation plan as shown in FIG. 2, and the addition of the aqueous solution and the initiator is controlled to start and stop at the timings shown above. It becomes possible to do.

  As an example, FIG. 2 shows the transition of the manufacturing process on the timeline when the manufacturing apparatus is provided with five polymerization tanks 12 described above. Each arrow in the polymerization tank No. 1 to No. 5 indicates the occupation time of the polymerization tank 12 from the start of the addition of the aqueous solution to the polymerization tank 12 until the completion of the removal of the finally obtained aqueous gel. Each arrow in the aeration tank No. 1 and No. 2 indicates the occupation time of the aeration tank 11 from the start of dropping of the aqueous solution into the aeration tank 11 until the end of the aeration process. In this case, it is more preferable that two aeration tanks 11 are provided as shown in FIG. It is preferable that the aeration in the aeration tank 11 takes about 10 to 30 minutes, and the dropping of the aqueous solution after completion of the aeration to the one polymerization tank 12 also takes about 5 to 10 minutes, so that it is further emptied thereafter. Considering the time for supplying the aqueous solution to the aeration tank 11 and the time required for switching between the respective processes, it takes 30 minutes or more to send out the aqueous solution aerated by the aeration tank 11 once. Therefore, if one aeration tank 11 is used, the aeration tank 11 becomes a bottleneck, but there are two aeration tanks 11 so that each aeration tank 11 can feed the aqueous solution to each polymerization tank 12. For example, this bottleneck is eliminated, and the time during which the respective facilities are not moving can be minimized.

  The present invention will be described more specifically with reference to examples. First, the raw materials and chemicals used are described. First, acrylamide and acrylic acid were used as an acrylic monomer, and a 26 wt% aqueous solution was prepared by mixing at respective weight mixing ratios described later.

<Drug>
Azo initiator: 2,2-azobis (2-amidinopropane) hydrochloride (hereinafter abbreviated as “ABAP”)
Oxidant initiator: tert-butyl hydroperoxide (Nippon Yushi Co., Ltd .: 69% by weight, hereinafter abbreviated as “BHP”)
Reducing agent: sodium hydrosulfite (manufactured by Wako Pure Chemical Industries, Ltd .: NSO powder, hereinafter abbreviated as “NSO”)
・ Polymerization inhibitor: Copper sulfate aqueous solution (use 2.5% by weight)

  Next, the manufacturing apparatus to be used will be described. An inlet pipe with a valve capable of introducing an aqueous solution at 200 liters / min is connected to the lower part of an aeration tank with an internal capacity of 1000 liters, and the tip of the pipe is attached to the upper lid of the polymerization tank with an internal capacity of 1000 liters fixed on the floor surface. Connected to the provided inlet. The introduction tube was a flexible tube that could be bent freely. Further, the upper lid was placed on the main body of the polymerization tank from above so that the polymerization tank could be sealed with a sealing material provided at a contact portion with the polymerization tank. The height from the bottom valve of the aeration tank to the upper lid of the polymerization tank was 3 meters. The polymerization tank was not provided with any stirring device, and the wall surface inside the polymerization tank was flat.

  In addition, an initiator charging device that stores azo-based initiator, oxidant-based initiator, and reducing agent is provided, and each initiator is connected by connecting a connecting pipe to the inlet of the upper lid of the polymerization tank. The agent can be added individually. This connecting tube is also a flexible tube that can be bent freely. Further, an additive charging apparatus capable of introducing a polymerization inhibitor was provided in the aeration tank. The aeration tank was provided with an aeration device for bubbling nitrogen in the liquid.

Example 1
1000 liters of an aqueous solution using only acrylamide (AAM) as an acrylic monomer was introduced into an aeration tank, a polymerization inhibitor; 25 ml of an aqueous copper sulfate solution was added from the additive charging device 16, and nitrogen was bubbled for 20 minutes. Aeration was performed. Polymerization in the aeration tank was not observed. In parallel with this, an upper lid was set in an empty polymerization tank, and the atmosphere was replaced with nitrogen over 20 minutes. The aerated aqueous solution was vigorously passed through the introduction pipe at a rate of 100 liters per minute and started to be charged into the polymerization tank to generate a water flow in the polymerization tank. The temperature of the aqueous solution during introduction was 0 ° C. Addition of 12% ABAP aqueous solution was started in a fluidized state when 100 liters of aqueous solution was introduced into the polymerization tank (about 1 minute), and 3 liters were added in about 5 minutes. Next, when 600 liters of aqueous solution was introduced into the polymerization tank, 0.1 liter of 10 wt% BHP aqueous solution was added in 30 seconds. Furthermore, when 700 liters of aqueous solution was introduced into the polymerization tank, 0.1 liter of 5 wt% NSO aqueous solution was added in 30 seconds. The introduction of the aqueous solution was stopped when 1000 liters of the aqueous solution was introduced into the polymerization tank, that is, 2.5 minutes after the end of the addition of NSO.

  After 10 minutes from the end of the addition of the aqueous solution, the polymerization exotherm was confirmed over 20 minutes, and then allowed to stand and polymerized for 3 hours. Then, the upper lid of the polymerization tank is removed while being connected to the connection pipe and the introduction pipe from the initiator addition device, the solidified acrylamide polymer in the polymerization tank is tilted by about 90 degrees, and the polymerization tank wall surface is separated by its own weight. After making a gap between them and making it easy to peel off, it was turned over so that it would turn upside down, so that an aqueous acrylamide polymer gel jumped out alone during the fall.

  The mass of the acrylamide polymer taken out, which is an aqueous gel, was finely divided to a particle size of 2 to 3 mm so that it could be easily dried. The finely divided aqueous gel was dried with a hot air dryer at 100 ° C. to a water content of 10% by weight or less, and then pulverized to obtain a powder having a particle size of 1 mm or less. The quality of the powder was analyzed as follows.

<1% salt viscosity measurement>
To a 500 ml beaker, 475 g of water was taken, and 5.0 g of the above powder was added and dissolved over 4 hours while stirring at 280 rpm. After adding 20 g of sodium chloride to this and stirring for another 30 minutes, the viscosity was measured by a rotational viscometer (BROOKFIELD type: model DV-I) and found to be 3000 mPa · s. The viscosity was measured at a temperature of 25 ° C. and rotor No. 2, It implemented on condition of rotation speed 6rpm.

<Measurement of insoluble matter>
499.5 g of water was placed in a 500 ml beaker, and 0.5 g of the above powder was added and dissolved over 4 hours while stirring at 280 rpm. 5 g of sodium chloride was added thereto, and the mixture was further stirred for 5 minutes, filtered through an 83 mesh screen, and the weight of insoluble matter was measured to find 3 g.

(Examples 2 to 7)
Acrylamide and acrylic acid (ACA) were mixed at the mixing ratios shown in Table 1 to obtain 1000 liters of a 26 wt% aqueous solution. Each aqueous solution was charged into the polymerization tank from the aeration tank at the same rate as in Example 1, and at the same timing and required time as in Example 1, addition of each initiator in the amount shown in Table 1 was started. The addition was carried out over the time described in 1. In addition, when the input amount is different from that in Example 1, the input start timing and the input speed are the same as those in Example 1, and the input end time is different. Otherwise, an acrylic polymer was obtained by the same procedure as in Example 1, and was taken out and measured in the same manner as in Example 1. The results are shown in Table 1. The polymerization induction period in the table is the time from the start of the introduction of the last initiator to the time when a temperature rise of about 0.2 to 0.3 ° C. is confirmed due to heat generated by the polymerization.

The conceptual diagram of the manufacturing apparatus for enforcing the manufacturing method concerning this invention Conceptual diagram of the timeline when performing polymerization in five polymerization tanks (A) Schematic diagram of a production apparatus for obtaining a conventional acrylic polymer having a stirring blade, (b) Conceptual diagram at the time of taking out after polymerization

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymerization tank 2 Stirring blade 3 Aqueous solution 4 Aeration pipe 10 Dissolution tank 11 Aeration tank 11a Aeration apparatus 12 Polymerization tank 13 Introduction pipe 14 Valve 15 Initiator introduction apparatus 16 Additive introduction apparatus 17 Injection pipe 18 Top cover AA Acrylic monomer ( Aqueous solution)
WATER water

Claims (6)

In producing an acrylic polymer by polymerizing an acrylic monomer using a polymerization initiator,
A method for producing an acrylic polymer, comprising mixing an aqueous solution of a deoxygenated acrylic monomer and a polymerization initiator, and then performing polymerization while leaving the mixed solution in a stationary state.   When mixing one or both of the acrylic monomer aqueous solution and the polymerization initiator in the polymerization tank, the flow energy of the acrylic monomer aqueous solution is used. The method for producing an acrylic polymer according to claim 1, wherein   The aqueous solution of the acrylic monomer is adjusted in advance in a dissolution tank at a position higher than the polymerization tank in which the polymerization is performed, and charging of the aqueous solution into the polymerization tank is performed with the dissolution tank and the polymerization tank. The method for producing an acrylic polymer according to claim 1 or 2, wherein the difference in height is used.   The method for producing an acrylic polymer according to any one of claims 1 to 3, wherein a polymerization tank that does not have a stirrer is used as a polymerization tank for performing polymerization.   As the polymerization initiator, with respect to the acrylic monomer, an azo initiator of 100 ppm to 500 ppm by weight, an oxidizing agent of 1 ppm to 500 ppm and an oxidizing agent of 1 ppm to 500 ppm. The method for producing an acrylic polymer according to any one of claims 1 to 4, wherein a redox initiator combined with a reducing agent of not more than ppm is used.   The method for producing an acrylic polymer according to any one of claims 1 to 5, wherein the acrylic monomer is acrylamide or a mixture of polymerizable monomers mainly composed of acrylamide.

Images