JP5214155B2 - Water-soluble polymer production apparatus and continuous production method of water-soluble polymer - Google Patents

Description

  The present invention relates to a water-soluble polymer production apparatus and a continuous production method of a water-soluble polymer using such an apparatus.

  Water-soluble polymers have excellent basic performance as thickeners, adhesives, flocculants, hygroscopic agents, desiccants, surface modifiers, tackifiers, dispersants, etc. and are widely used in industry. ing. For example, in addition to drilling soil treatment agent, poultice and poultice additive, dredging treatment agent, medicine, paint, papermaking, detergent or cosmetics, water treatment, textile treatment, civil engineering or agriculture / horticulture, adhesive, Widely used in fields such as ceramics and manufacturing processes. Further, a water-soluble polymer having a higher quality in terms of viscosity, the amount of remaining monomer, and the like is used for food or feed as a thickener or a loosening accelerator, for example.

  Conventionally, as a method for producing a water-soluble polymer, a method for producing high-concentration sodium polyacrylate by batch polymerization with controlled foaming and temperature is known (for example, see Patent Document 1). Patent Document 1 describes a batch-type reactor having a cooling device, a tank reactor, and a stirring mixer. However, this manufacturing method requires a large-scale apparatus to ensure high productivity. Furthermore, the molecular weight distribution (Mw / Mn) of the obtained polymer becomes relatively large, and further devices are required to obtain a polymer having a desired molecular weight distribution. The molecular weight distribution (Mw / Mn) is represented by a quotient obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn).

  Further, a continuous production method of polyacrylic acid having a narrow molecular weight distribution using a plurality of reactors installed in series is known (see, for example, Patent Document 2 and Patent Document 3). In the examples described in these patent documents, a stirred tank series continuous reactor having a tank-type first to third reactor and, if necessary, a cooling device and a stirring mixer in the second reactor. Is described. This reaction apparatus is called “continuous type”, but substantially, the stirring tank is connected in series as the first to third reactors, and the reaction liquid is sequentially supplied from the first reactor to the third reactor. It is a system which is sent and taken out from the third reactor. In such a series reactor, the reduction in reaction time and productivity, and the heat removal efficiency are often insufficient for industrially efficient production of polyacrylic acid.

  On the other hand, a continuous production method of polyacrylic acid having a narrow molecular weight distribution using a loop-type circulation line is known (for example, see Patent Document 4). Patent Document 4 describes a circulation type continuous reaction apparatus having a tubular reactor and a motionless mixer. However, this production apparatus also often has a short reaction time and productivity, and heat removal efficiency, which is insufficient for industrially producing polyacrylic acid efficiently.

In addition, even if a water-soluble polymer having a desired molecular weight distribution can be obtained with high efficiency on a laboratory scale, a water-soluble polymer having a desired molecular weight distribution cannot be obtained on an actual production equipment scale. May cause problems.
JP-A-2004-244617 (second, pages 8 to 10, 41) JP 2003-002909 A (pages 2-7) Japanese Unexamined Patent Publication No. 2003-040912 (pages 2 and 5-8) JP 2001-098002 A (page 2-9) Japanese Examined Patent Publication No. 48-20532 (page 1-2) JP 47-31924 A (page 1-2) Japanese Patent Laid-Open No. 49-11820 (page 1-2)

  The present invention has been made in order to solve the above-described conventional problems, and its object is to provide a continuous production method in which a water-soluble (co) polymer having a narrow molecular weight distribution can be obtained on an industrial scale and with high efficiency. And a manufacturing apparatus capable of performing such a method.

  The water-soluble polymer production apparatus of the present invention includes a tank for temporarily storing a circulating liquid containing a monomer having a polymerizable unsaturated bond; and circulates outside the tank and returns to the tank A circulation line for circulating the circulating fluid; and a discharge line for discharging a part of the circulating fluid. The circulation line has at least one cooler, and the tank has stirring means using a stirring blade selected from the group consisting of a paddle stirring blade, a saddle stirring blade, a lattice stirring blade, and a large flat blade. Is provided. In a preferred embodiment, the discharge line is provided separately from the steam circulation line. In the continuous production method of the water-soluble polymer of the present invention, a circulating liquid containing a monomer having a polymerizable unsaturated bond is circulated through a circulation line that leaves the tank, circulates outside the tank, and returns to the tank. In this way, the monomer is polymerized while the water-soluble polymer is continuously produced. The method comprises the steps of cooling the circulating fluid at at least one location of the circulating line; discharging a part of the circulating fluid out of the circulating line; and stirring the circulating fluid in the tank. In addition, the stirring is performed using a stirring blade selected from the group consisting of a paddle stirring blade, a saddle stirring blade, a lattice stirring blade, and a large flat blade.

  According to the present invention, the effects described below are obtained synergistically, whereby a water-soluble polymer having a very narrow molecular weight distribution can be produced with very high productivity. Moreover, even if the scale is scaled up to industrial production scale, a water-soluble polymer having a very narrow molecular weight distribution can be produced with very high productivity as in the laboratory scale. More specifically, it is as follows: A continuous production apparatus using a loop-type circulation line is basically excellent in productivity. By providing a cooler in the circulation line of such a continuous production apparatus, the temperature distribution in the circulation line and the tank can be made uniform, and the temperature can be easily controlled. As a result, since the monomer can be reacted at a high polymerization concentration, the concentration of the residual monomer can be extremely reduced, and very excellent productivity is realized. Furthermore, according to such a manufacturing apparatus (and a manufacturing method using such an apparatus), a ripening step is not required and a polymerization reaction can be performed in a short reaction (residence) time, thereby further improving productivity. Can be made. In the prior art, in order to obtain a polymer having a narrow molecular weight distribution, it is necessary to lower the polymerization concentration, increase the reaction time, or reduce the production amount per hour. By exhibiting the above properties synergistically, a water-soluble polymer having a very narrow molecular weight distribution can be produced with very high productivity. In addition, although the reason is not clear, even if a water-soluble polymer having a desired molecular weight distribution is obtained on a laboratory scale, a water-soluble polymer having a desired molecular weight distribution can be obtained by scaling up to an industrial production scale. Often not. According to the present invention, by providing the tank with a stirring means using paddle type stirring blades, vertical stirring blades, lattice type stirring blades or large plate blades, even if scaled up to industrial production scale, Similarly, water-soluble polymers having a very narrow molecular weight distribution can be produced with very high productivity.

A. Water-Soluble Polymer Manufacturing Device FIG. 1 is a conceptual diagram illustrating a water-soluble polymer manufacturing device according to one embodiment of the present invention. FIG. 2 is a conceptual diagram illustrating a water-soluble polymer production apparatus according to another embodiment of the present invention. The water-soluble polymer production apparatus 100 includes a tank 1, a circulation line 2, and a discharge line 3. The tank 1 temporarily stores a circulating liquid containing a monomer having a polymerizable unsaturated bond. The circulation line 2 exits from the outlet a of the tank 1, circulates outside the tank 1, and returns to the return port b of the tank 1 (that is, the circulation line is a so-called loop type). The circulation line 2 is usually provided with a circulation pump 6 and a mixing device 5, and circulates the circulating liquid while mixing. While the circulating fluid circulates through the circulating line, the polymerization of the monomer in the circulating fluid proceeds. In addition, the circulation line 2 is usually provided with monomer and various additive supply ports (in the form of FIGS. 1 and 2, supply ports 7, 8, 9 and 10). Such a supply port may be provided at an arbitrary position of the tank 1. In the present invention, the circulation line 2 has at least one cooler 4. By providing the cooler 4 in the circulation line 2, a water-soluble polymer having a narrow molecular weight distribution can be obtained. Furthermore, in the manufacturing apparatus of the present invention, the tank 1 is provided with a stirring means 12 using a specific stirring blade (described later). In one embodiment, such a stirring means 12 stirs the circulating fluid in the tank with a stirring required power Pv of 0.5 kW / m ³ or more. By providing a stirring means using a specific stirring blade in the tank, a water-soluble polymer having a narrow molecular weight distribution can be obtained even on an industrial scale production line. The discharge line 3 discharges a part of the circulating liquid from the circulation line 2 and collects the resulting polymer. Hereinafter, the components of the water-soluble polymer production apparatus will be described in detail. In the present specification, for convenience, the tank and the circulation line may be collectively referred to as “reaction apparatus”, and the reaction apparatus and the discharge line may be collectively referred to as “production apparatus”. Furthermore, monomers and various additives may be collectively referred to as “raw materials”.

  The circulation line 2 is configured as any appropriate piping. The material constituting the tube is preferably SUS. It is because it is excellent in heat transfer and corrosion resistance and does not affect the polymerization reaction. Specific examples include SUS304, SUS316, SUS316L, and the like. If necessary, any appropriate scale inhibitor may be applied to the inner surface of the circulation line (surface in contact with the circulating fluid).

  In the present invention, as described above, the circulation line 2 is provided with at least one cooler 4. By providing a cooler, it is possible to remove heat of reaction such as heat of polymerization, heat of dilution, heat of neutralization, heat of decomposition, heat of dissolution, etc., and make the temperature distribution in the reactor uniform, The temperature in the reactor can be easily controlled. As a result, a water-soluble polymer having a narrow molecular weight distribution can be obtained. If the cooler is not provided, the reaction heat cannot be removed sufficiently, and the polymerization reaction may proceed rapidly. As a result, handling may be difficult. Specifically, the reaction liquid (circulating liquid) reaches the boiling point, a large amount of Michael adduct is generated, or the chain transfer agent may not function sufficiently when a chain transfer agent is used. .

  In particular, the water-soluble polymer production apparatus of the present invention uses a monomer (for example, polymerization of (meth) acrylic acid, its salt, ester, acrylamide, its N-substituted product, etc.) that advances the polymerization reaction quickly. It can be suitably applied to. By providing a cooler, a sufficiently mild polymerization reaction can be achieved even in such a case. In particular, in the polymerization reaction of acrylic acid and / or a salt thereof, depending on the reaction conditions such as the initiator used, the reaction is so fast that 90% or more of the monomer is converted into a water-soluble polymer in 30 seconds. The reaction heat is also large. Even in such a case, the polymerization reaction can be controlled by appropriately providing a cooler in the circulation line.

Any appropriate cooler can be adopted as the cooler as long as the heat of reaction can be removed by lowering the temperature of the circulating liquid passing through the cooler. The proportion of reaction heat to be removed can vary depending on the purpose and reaction system. In one embodiment, the cooler can remove 1% or more, more preferably 30% or more, still more preferably 50% or more, particularly preferably 70% or more of the generated reaction heat. By removing the reaction heat, the temperature of the circulating liquid (polymerization temperature) can be controlled within a desired range according to the purpose. If the heat of reaction is not sufficiently removed, the molecular weight distribution of the water-soluble polymer obtained may not be sufficiently narrow. Further, in the cooler, S / V is preferably 5 or more, more preferably 6.5 or more, and particularly preferably 8 or more. Here, V is the volume of the circulating fluid (total amount of circulating fluid in the circulating line and tank) [m ³ ], and S is the heat transfer area [m ² ] of the cooler. Particularly preferably, the cooler satisfies both the reaction heat removal efficiency and the S / V. A higher cooling efficiency of the cooler is preferable because a water-soluble polymer having a narrow molecular weight distribution can be obtained with a short residence time (that is, with very high productivity).

  The shape or type of the cooler can be appropriately set according to the purpose. Any suitable cooler or heat exchanger shape or type may be employed as the cooler shape or type. Specific examples include a multi-tube cylindrical type, a double tube type, a plate type, an air cooler, an irrigation cooler, a coil type, a spiral type, and a jacket. These may be employed alone or in combination. For example, in the case of a jacket or the like, the length in contact with the pipe or the tank is not particularly limited.

  The installation number and installation position of the coolers can also be appropriately set according to the purpose. For example, the number of installed coolers may be one or plural. FIG. 1 shows a case where one cooler is provided upstream of the monomer and various additive supply ports 7, 8, 9 and 10 (details will be described later) in the circulation line. FIG. 2 shows a case where one cooler is provided upstream and downstream of the monomer and various additive supply ports 7, 8, 9 and 10 (two in total). Although not shown, it goes without saying that three or more coolers may be provided. In the case where a plurality of units are installed, a plurality of units may be installed together in one circulation line. For example, they may be installed in a plurality of locations on the circulation line as shown in FIG. It is preferable to disperse and install in a plurality of places. This is because the cooling efficiency is further improved. For example, when using a monomer that generates a large amount of heat of reaction, it is particularly preferable to disperse and install a plurality of monomers. The installation position of the cooler is not limited to the illustrated example. For example, it may be provided immediately downstream of the tank outlet a, may be provided immediately upstream of the return port b, or may be provided in both of them. The cooler may be provided at least in the circulation line of the reaction apparatus. Therefore, the cooler may be provided only in the circulation line, or may be provided in both the circulation line and the tank. Preferably, the cooler is provided only in the circulation line. This is because it is not necessary to pay attention to the temperature gradient and concentration gradient of the circulating fluid in the tank (these may increase the molecular weight distribution of the resulting polymer). Even if a cooler such as a jacket or a double pipe is not provided, the temperature of the circulating fluid can be lowered to some extent by simply increasing the length of the circulation line. However, according to such means, the construction cost of the circulation line piping and device laying increases, and the pumping capacity needs to be strengthened. Furthermore, even if a very long circulation line is provided and the pumping capacity is strengthened, sufficient cooling capacity is often not obtained. As a result, the temperature gradient in the circulation line becomes large. In many cases, a polymer having the above characteristics cannot be obtained. In addition, such a long circulation line has a problem of insufficient productivity.

  As the circulation pump 6, any appropriate circulation pump can be adopted as long as the circulating liquid can be circulated to a degree sufficient to obtain a desired water-soluble polymer. The installation position, number, type, and the like of the circulation pump can be appropriately set according to the purpose. 1 and 2, one circulation pump is provided between the tank and the branch point from the circulation line to the discharge line.

  As the mixing device 5, any suitable mixing device that can make the concentration distribution of the circulating fluid uniform enough to obtain a desired water-soluble polymer can be adopted. The installation position, number, type, and the like of the mixing device can be appropriately set according to the purpose. For example, the mixing device 5 may be provided at least in the circulation line, and thus may be provided in the tank and / or the discharge line in addition to the circulation line. Specific examples of the mixing device include a motor driven type represented by a stirring blade such as a paddle blade, Max Blend (registered trademark), an anchor blade, etc .; a surface driven type represented by a shaker, etc .; an injection collision type; an ultrasonic dispersion type A motionless mixer. Preferred are a paddle blade, Max blend, a stirring device using an anchor blade, and a motionless mixer, more preferably a stirring device using a paddle blade or an anchor blade and a motionless mixer, and more preferably a motionless. It is a mixer. By providing a motionless mixer in the circulation line, the monomer and additive (for example, polymerization initiator, chain transfer agent) in the circulation liquid are efficiently mixed, so that the concentration gradient of the circulation liquid is reduced and more There is an advantage that a uniform circulating fluid can be obtained.

  As described above, the circulation line 2 is usually provided with a supply port for monomers and various additives. The number and installation positions of the supply ports can be appropriately set according to the type and molecular weight of the target polymer. For example, as shown in FIGS. 1 and 2, supply ports 7, 8, 9 and 10 may be provided. In one embodiment, an alkali agent or an oxidizing agent is supplied from the supply port 7, a monomer is supplied from the supply port 8, a chain transfer agent is supplied from the supply port 9, and a polymerization initiator is supplied from the supply port 10. (Or polymerization accelerator) may be supplied. By providing the monomer supply port at a predetermined position in the circulation line, stirring is not necessarily required, which is very advantageous in terms of manufacturing cost of the apparatus and ease of installation. Needless to say, additives other than those described above (for example, scale inhibitors) may be supplied. Moreover, although not shown, when the polymerization is performed in an inert gas atmosphere, such a gas inlet may be provided at an appropriate location. More specific installation forms of the monomer and additive supply ports will be described below. The monomer supply port, the polymerization initiator supply port, and other component supply ports will be described in this order.

  For example, in the form in which only one cooler as shown in FIG. 1 is provided, the monomer supply port 8 is connected to the tank from the cooler as shown in FIG. 1 in the flow direction of the circulating liquid in the circulation line. Or between the tank and the cooler. When it is located between the cooler and the tank, the monomer can be supplied downstream of the cooler, so that it is easy to recover even if an unforeseen situation such as the circulation line is blocked. is there. When it is located between the tank and the cooler, there is an advantage that an undesirable side reaction can be suppressed in a reaction system having a significantly large heat of reaction. In addition, for example, in a form in which a motionless mixer is provided in the circulation line, the monomer supply port 8 may be provided in any place of the circulation line. More specifically, the monomer supply port 8 may be provided in the motionless mixer, or may be provided between the tank and the motionless mixer in the flow direction of the circulating liquid in the circulation line. Well, it may be provided between the motionless mixer and the tank. Preferably, the monomer supply port is provided in the motionless mixer or between the tank and the motionless mixer. Particularly preferably, the monomer supply port is provided between the cooler and the motionless mixer in the direction of the circulating fluid flow path. By adding the monomer in or just before the motionless mixer, the supplied monomer is immediately stirred, and the monomer concentration distribution becomes uniform. Coalescence can be obtained.

  For example, in the embodiment in which only one cooler as shown in FIG. 1 is provided, the polymerization initiator supply port 10 is connected to the tank from the cooler as shown in FIG. Or between the tank and the cooler. When it is located between the cooler and the tank, there is an advantage that the circulating fluid can be easily kept at a constant temperature when returning to the tank, and the temperature gradient can be extremely reduced. When located between the tank and the cooler, the initiator concentration is uniform in a remarkably fast reaction system, and there is an advantage that undesired runaway reaction at the supply port can be suppressed. For example, in a form in which a motionless mixer is provided in the circulation line, the polymerization initiator supply port 10 may be provided between the tank and the motionless mixer in the direction of the flow path of the circulating liquid in the circulation line. It may be provided between the motionless mixer and the tank. In any case, the circulating liquid can be sufficiently mixed by the motionless mixer.

  The relative positional relationship among the polymerization initiator supply port 10, the monomer supply port 8, the cooler 4, and the mixing device 5 is not particularly limited. For example, the polymerization initiator supply port 10 may be provided downstream of the monomer supply port 8 as shown in FIG. 1 and FIG. It may be provided. Further, in the direction of the circulating fluid in the circulation line, a polymerization initiator supply port 10 is provided downstream of the mixing device (for example, motionless mixer) 5 and a monomer supply port 8 is provided upstream of the mixing device 5. Alternatively, the polymerization initiator supply port 10 may be provided upstream of the mixing device 5 and the monomer supply port 8 may be provided downstream of the mixing device 5. Both the supply port 10 and the monomer supply port 8 may be provided upstream of the mixing device 5, and both the polymerization initiator supply port 10 and the monomer supply port 8 may be provided downstream of the mixing device 5. . Further, for example, in a mode in which only one cooler as shown in FIG. 1 is provided, the polymerization initiator supply port 10 is provided upstream of the cooler 4 and the monomer supply port 8 is provided downstream of the cooler 4. Alternatively, the polymerization initiator supply port 10 may be provided downstream of the cooler 4 and the monomer supply port 8 may be provided upstream of the cooler 4. The polymerization initiator supply port 10 and the monomer supply port 8 may be provided. Both may be provided upstream of the cooler 4, and both the polymerization initiator supply port 10 and the monomer supply port 8 may be provided downstream of the cooler 4. A preferred arrangement is as follows: cooler 4 / monomer supply port 8 / mixing device 5 / polymerization initiator supply port 10; cooler 4 / monomer supply port 8 / polymerization in the flow direction of the circulating liquid in the circulation line. The initiator supply port 10 / mixing device 5 is particularly preferable, and the cooler 4 / monomer supply port 8 / polymerization initiator supply port 10 / mixing device 5 is particularly preferable. Furthermore, for example, in a form in which two coolers as shown in FIG. 2 are provided, a particularly preferable arrangement is the cooler 4 / monomer supply port 8 / mixing device 5 / polymerization initiator supply port 10 / cooler 4. It is. For example, when the viscosity of the circulating fluid is low, the monomers and the like are supplied in the above arrangement (order) so that they are mixed very quickly and the concentration gradient can be made uniform quickly. As a result, there is an advantage that a water-soluble polymer having a very narrow molecular weight distribution can be obtained.

  The number and position of the supply ports for the other components can be set appropriately according to the purpose. For example, as shown in FIGS. 1 and 2, two supply ports 7 and 9 may be provided, only one supply port may be provided, or three or more supply ports may be provided. In the form shown in FIGS. 1 and 2, an alkali agent, an oxidizing agent, or the like can be supplied from the supply port 7 and a chain transfer agent can be supplied from the supply port 9. Preferably, these supply ports are provided between the discharge line and the tank in the direction of the circulating fluid flow path. When the tank, the discharge line, and the cooler are arranged in this order in the flow direction of the circulating fluid in the circulation line, these supply ports are preferably between the cooler and the tank or the discharge line. To the cooler. When the circulation line has a motionless mixer, these supply ports are preferably provided upstream of the motionless mixer in the direction of the circulating fluid flow path. By installing in such a position, it can be uniformly mixed with monomers and the like at an early stage by a motionless mixer. A particularly preferable arrangement is the alkali agent supply port 7 / monomer supply port 8 / chain transfer agent supply port 9 / mixing device 5 / polymerization initiator supply port 10 in the direction of the circulating fluid flow path in the circulation line.

  It goes without saying that the supply ports for the monomer and various additives may be provided at positions other than those described above. For example, at least one of the monomer and various additive supply ports 7, 8, 9 and 10 may be provided in the tank, may be provided immediately downstream of the tank outlet a, or immediately upstream of the tank return port b. These may be provided in combination.

  The tank 1 may have any appropriate configuration as long as the circulating fluid can be temporarily stored. For example, the material constituting the tank is the same as the circulation line. Any appropriate scale inhibitor may be applied to the inner surface of the tank (the surface in contact with the circulating fluid) as necessary. Preferably, the tank not only stores and circulates the circulating liquid, but can also function as a polymerization vessel for advancing the polymerization reaction of the circulating liquid. When the tank functions as a polymerization vessel (that is, by constituting a part of the reaction apparatus), the productivity of the water-soluble polymer can be increased. Furthermore, when the production of a low molecular weight polymer is intended, the desired low molecular weight polymer can be obtained even if the concentration of the circulating liquid and the monomer supply amount are increased. In a continuous polymerization method using a conventional loop reactor (circulation line), a desired low molecular weight polymer can be obtained by increasing the concentration of circulating fluid and the amount of monomer supply in order to increase productivity. could not. On the other hand, according to the present invention, by providing a tank as a part of the reaction apparatus, a desired low molecular weight polymer can be produced with high productivity even if the concentration of the circulating liquid and the monomer supply amount are increased. Can be obtained at If necessary, the tank may be provided with a gas-liquid separator, and the circulation line may be circulated while removing the gas of the circulating liquid.

  The tank preferably has a predetermined ratio of volume to the volume of the circulation line. More specifically, the volume of the tank is preferably 10% by volume or more, more preferably 30% by volume or more with respect to the volume of the entire circulation line. When the volume of the tank is less than 10% by volume, the piping becomes very long as a result, and pressure loss or the like may occur. As a result, the tank may not function sufficiently as a polymerization vessel, and productivity may be insufficient. On the other hand, the volume of the tank is preferably 90% by volume or less, and more preferably 75% by volume or less, with respect to the volume of the entire circulation line. When the volume of the tank exceeds 90% by volume, it is necessary to increase the circulation speed very much in order to set the circulation ratio (described later) in an appropriate range. As a result, the pump needs to be large and the pressure loss may increase. Furthermore, heat removal may be insufficient. In the present specification, for convenience, the tank may be referred to as a recycle tank.

  The tank and the circulation line are connected by an outlet a and a return port b. That is, the circulation line 2 exits from the outlet a of the tank 1, circulates outside the tank 1, and returns to the return port b of the tank 1. The outlet a and the return port b are provided at any appropriate place in the tank. In the illustrated example, the outlet a is provided at the bottom of the tank, and the return port b is provided at the top of the tank.

In the present invention, the tank 1 is provided with stirring means 12. Examples of the stirring means 12 include a stirring device using a paddle type stirring blade, a saddle type stirring blade, a lattice type stirring blade, or a large flat plate blade. Specific examples of the large plate blade include a Max Blend (registered trademark) type stirring blade, a full zone type stirring blade, a supermix type stirring blade, and a Sammel type stirring blade. By using such a stirring means, the circulating fluid in the tank can be stirred with a required stirring power Pv of a predetermined value (for example, 0.5 kW / m ³ ) or more. Further, by using such a stirring means, turbulent flow is generated in the circulating liquid in the tank, and stirring can be performed not only in the horizontal direction but also in the vertical direction. For example, even if stirring is performed with a very large required power for stirring, depending on the shape of the stirring blade, only a laminar flow may be generated or so-called co-rotation may occur, and the power required for stirring may not sufficiently contribute to stirring. According to the present invention, by using the stirring means as described above, a sufficiently large stirring power can be realized, and very good stirring can be realized. For example, a paddle type stirring blade can send liquid (that is, stir) not only in the horizontal direction but also in the upper direction by inclining the blade, and can achieve stirring that speeds up the mixing in the system. The vertical stirring blade can send liquid not only in the horizontal direction but also upward due to the splashed portion in the vertical direction of the vertical bowl, and can achieve stirring that speeds up mixing in the system. Since the lattice-type stirring blade shears the liquid by the lattice, it is possible to realize stirring that speeds up the mixing in the system. Since the Max Blend type stirring blade is configured by combining the lower paddle blade and the upper lattice blade, the effects of the paddle type stirring blade and the lattice type stirring blade can be obtained synergistically. By providing such a stirring means in the tank, even if the flow rate of the circulating fluid in the reaction apparatus becomes high, very good stirring is performed in the tank, and the concentration distribution of the circulating fluid in the tank Is extremely uniform, so that the formation of a polymer having a molecular weight higher than the desired molecular weight or a polymer having a molecular weight lower than the desired molecular weight can be suppressed. As a result, a water-soluble polymer having a narrow molecular weight distribution can be obtained even on an industrial scale production line. In general, the stirring device includes a drive unit, a transmission unit, and a stirring blade. The drive unit and the transmission unit may have any suitable shape and / or style as long as the desired stirring power Pv can be obtained. Specific examples of the drive unit include electric drive, hydraulic drive, and air drive (air motor). For example, the transmission unit can include an inverter and a transmission gear.

  The discharge line 3 is configured as any appropriate piping. The material which comprises a pipe | tube is the same as that of the said circulation line. The discharge line 3 may be provided at any position of the reaction apparatus. Preferably, the discharge line 3 is provided separately from the circulation line 2. This is because piping is simple, equipment is simplified, and cost is advantageous. Only one discharge line or two or more discharge lines may be provided depending on the purpose.

  The discharge line 3 is configured so that the circulation ratio is preferably 3 or more, more preferably 5 or more, still more preferably 9 or more, and particularly preferably 10 or more. If the circulation ratio is 3 or more, a water-soluble polymer having a small concentration gradient and a narrow molecular weight distribution can be obtained with high productivity. The circulation ratio is defined by (amount of circulating liquid returning to the tank) / (amount of discharged liquid discharged from the reactor). By appropriately adjusting the circulation ratio and the cooling efficiency of the cooler, a water-soluble polymer having a very narrow molecular weight distribution can be obtained with very high productivity. Examples of means for adjusting the circulation ratio include adjusting the discharge amount (driving force) of the pump, adjusting the opening of the circulation line and / or the discharge line, and combinations thereof.

  Preferably, the discharge line 3 has at least one cooler 4. By providing a cooler in the discharge line, the product obtained can be sufficiently removed from heat, and the apparatus can be simplified when there are post-treatments such as monomer removal and neutralization in the polymer. Specific examples of the cooler are as described above. In the form shown in FIGS. 1 and 2, the coolers are provided at two places on the discharge line.

  Preferably, the discharge line 3 has at least one mixing device. As the mixing device, a motionless mixer is preferable. By providing a mixing device (for example, a motionless mixer) in the discharge line, post-treatment such as mixing of an initiator for removing residual monomers and neutralization of a polymer can be easily performed.

  Preferably, the discharge line 3 comprises at least one monomer supply port. By providing a monomer supply port in the discharge line and mixing the discharge liquid (water-soluble polymer solution) and the monomer, the residual monomer contained in the water-soluble polymer (and the added monomer) ), The residual monomer contained in the resulting water-soluble polymer can be brought to a very low level. In the case where either a cooler or a motionless mixer is installed in the discharge line, a mode in which a monomer supply port is installed in at least one location upstream of the cooler or the motionless mixer is preferable. When both the cooler and the motionless mixer are installed, a mode in which a cooler is provided upstream of the motionless mixer and a monomer supply port is provided between the upstream cooler and the motionless mixer is preferable (see FIG. 1 and FIG. 1). FIG. 2 shows such a configuration). By arrange | positioning in this way, the reaction heat by addition of a monomer can be removed favorably, and discharge liquid can be adjusted to moderate temperature.

  The discharge line 3 may have a supply port for supplying the additive (for example, an alkali agent, a polymerization initiator or a polymerization accelerator, a chain transfer agent, and an oxidizing agent) as necessary. In the case where either a cooler or a motionless mixer is installed in the discharge line, a mode in which an additive supply port is installed in at least one location upstream of the cooler or the motionless mixer is preferable. When both a cooler and a motionless mixer are installed, a mode in which a cooler is provided upstream of the motionless mixer and an additive supply port is provided between the upstream cooler and the motionless mixer is preferable. By arrange | positioning in this way, the reaction heat by addition, such as a polymerization initiator, can be removed favorably, and discharged | emitted liquid can be adjusted to moderate temperature. Such a supply port may be provided separately from the monomer supply port, or may be used as a monomer supply port. When a plurality of monomer and / or additive supply ports are provided, the positional relationship can be appropriately set according to the purpose. In FIG. 1 and FIG. 2, the monomer and / or additive supply port is shown as one “agent supply port 11” for convenience.

B. Continuous production method of water-soluble polymer The continuous production method of the water-soluble polymer of the present invention is such that a circulating liquid containing a monomer having a polymerizable unsaturated bond is removed from the tank 1 and circulated outside the tank. Then, the monomer is polymerized while circulating in the circulation line 2 returning to the tank. Details will be described below.

  First, a monomer and various additives (for example, an alkali agent, a polymerization initiator or a polymerization accelerator, a chain transfer agent, an oxidizing agent, and a cross-linking agent) are supplied to the production apparatus described in the above section A as necessary. To do. The supply order of monomers and additives can be appropriately set according to the type of polymer, molecular weight, molecular weight distribution, and the like. For example, by supplying an alkaline agent or an oxidizing agent, the pH of the circulating liquid can be adjusted, and the monomer can be partially or completely neutralized; a polymerization accelerator and / or a chain transfer agent can be added. By using it, the polymerization reaction can be controlled and the molecular weight distribution of the resulting water-soluble polymer can be narrowed. In the embodiment using the production apparatus shown in FIGS. 1 and 2, the alkali agent, the monomer, the chain transfer agent, and the polymerization initiator can be supplied in this order while circulating the circulating liquid in a steady state. Examples of a method for supplying the monomer or the like to the tank include a method using a metering pump or the like while using a back pressure valve to prevent the circulating fluid from flowing backward. The amount of each additive added to the monomer can be appropriately set according to the purpose. Details of the monomer and various additives will be described in Section C below.

  As a supply form of the monomer and various additives, any appropriate supply form can be adopted as long as the effects of the present invention are obtained. In one embodiment, the monomer and various additives can be dissolved in an appropriate solvent in advance (for example, a solvent described in Section C below) and supplied as a solution to the circulation line. The concentration of such a solution can be appropriately set according to the type and molecular weight of the target polymer. In one embodiment, the monomer and various additives can be supplied to the circulation line under temperature control within an appropriate range. The temperature of the monomer or the like can be appropriately set according to the desired circulating fluid temperature (polymerization temperature) or the like. A monomer and various additives may be supplied continuously, may be supplied collectively, and may be supplied by dividing | segmenting intermittently. In the case of continuous supply, the supply amount per unit time may be constant, may be gradually increased or decreased, or may be changed stepwise. Furthermore, the supply amount per unit time can be increased or decreased according to the purpose. Needless to say, the supply forms described above may be combined as appropriate. In the case of producing a copolymer, a plurality of monomers may be supplied all at once or sequentially. The supply order in the case of supplying sequentially may be appropriately set according to the purpose (for example, a desired structure of the copolymer).

  The total amount of monomers and various additives supplied to the circulation line is preferably 0.1 to 50% by weight, more preferably 0.5%, based on the total amount of circulating liquid in the circulation line. -20% by weight. By controlling the supply amount in such a range, a water-soluble polymer having a narrow molecular weight distribution and few residual monomers can be obtained with high productivity. The flow rate of the circulating fluid can be appropriately set according to the purpose and the scale (production capacity) of the manufacturing apparatus. The flow rate of the circulating liquid may be constant or may be changed continuously or stepwise as the polymerization proceeds. The flow rate (or flow rate) of the circulating fluid can be appropriately set by the manufacturing apparatus. For example, when the total amount of the circulating fluid is 85 kg, the flow rate of the circulating fluid is preferably 1700 kg / h or more.

  In the production method of the present invention, the circulating liquid is cooled in at least one place of the circulating line. The preferred cooling position (cooler installation position) in the circulation line is as described in the above section A. By performing such a cooling treatment, the heat of reaction can be efficiently removed, so that the monomer can be polymerized at a high polymerization concentration. As a result, the time during which the circulating liquid stays in the reaction apparatus can be shortened, so that a water-soluble polymer can be obtained with very high productivity. The residence time will be described later.

  In one embodiment, the liquid temperature (polymerization temperature) of the circulating liquid in the said circulation line is 25-150 degreeC. The polymerization temperature is preferably 50 ° C. or higher, more preferably 70 ° C. or higher. The polymerization temperature is preferably 130 ° C. or lower, more preferably 99 ° C. or lower, and can be lower than 95 ° C. When the polymerization temperature is within such a range, sufficient productivity can be achieved with an appropriate polymerization time without causing an increase in molecular weight or an increase in impurities. When a polymerization initiator is used, the polymerization temperature can vary depending on the half-life of the polymerization initiator. For example, the polymerization temperature in the case of using a polymerization initiator is preferably 60 to 130 ° C, more preferably 70 to 120 ° C, and further preferably 80 to 120 ° C. In the production method of the present invention, the temperature of the circulating liquid can be efficiently controlled within a desired range by performing cooling at an appropriate position in the circulation line. As a result, there is an advantage that an inexpensive general-purpose polymerization initiator can be used. The temperature of the circulating fluid stored in the tank is also preferably in the above range. The polymerization temperature may be changed over time (increase or decrease in temperature) within a predetermined range as necessary.

  The polymerization temperature is preferably controlled within a predetermined range in the circulation line. For example, the difference between the temperature of the circulating fluid at the inlet of the circulation line (the outlet a of the tank 1) and the temperature of the circulating fluid at the outlet of the circulation line (the return port b of the tank 1) is preferably within 25 ° C. Preferably it is within 20 degreeC, More preferably, it is within 18 degreeC. By controlling the fluctuation range in the circulation line in such a range, a water-soluble polymer having a narrow molecular weight distribution can be obtained. Further, when a polymerization initiator is used, the decomposition rate can be made almost constant, so that a uniform polymerization reaction can be performed. The temperature of the circulating liquid at the inlet and outlet of the circulation line is preferably 10 to 90 ° C. Thereby, heat can be stably removed from the circulating fluid. This temperature can be controlled by appropriately setting the solution flow rate and the temperature of the cooling medium in the production apparatus.

Examples of the method for controlling the desired polymerization temperature and fluctuation range include feedback control in which the temperature of the circulating liquid is detected by a temperature sensor and the setting of the cooler is adjusted according to the detected value. For example, when the target polymerization temperature is T ° C., the control range is preferably T ° C. ± 10 ° C., more preferably T ° C. ± 7 ° C., and further preferably T ° C. ± 5 ° C. The temperature control by this feedback control can be more effective as the scale of the manufacturing apparatus (particularly the tank) is larger. This is because heat dissipation from the tank surface is reduced, and in particular, an effect of heat removal by the circulation line is likely to appear. Specifically, the volume of the production apparatus (tank) is preferably 1 m ³ or more, more preferably 3 m ³ or more, and further preferably 5 m ³ or more. In addition, when it is necessary to keep the circulating fluid warm, any appropriate means can be used. For example, controlling the temperature of the heat medium (or refrigerant) flowing in the jacket of the motionless mixer, adjusting the monomer supply amount, keeping the pipes and tanks warm (wrapping a heat insulator, etc.), circulation lines and tanks Supply of heat to

  According to the production method of the present invention, the monomer can be polymerized at a high polymerization concentration, and no aging step is required. Therefore, the residence time of the circulating liquid in the reactor can be shortened (that is, short). The monomer can be polymerized in the polymerization time). Here, the residence time refers to the total amount of circulating fluid / the discharge amount per unit time. The residence time is preferably 240 minutes or less, more preferably 120 minutes or less, still more preferably 80 minutes or less, and particularly preferably 60 minutes or less. On the other hand, the residence time is preferably 3 minutes or more. According to the production method of the present invention, a water-soluble polymer having a narrow molecular weight distribution can be obtained very efficiently with such a short residence time. Furthermore, a water-soluble polymer excellent in various properties such as clay dispersibility can be obtained. Note that, when the residence time is shortened, the productivity is increased while the heat of reaction per unit time is increased. In the production method of the present invention, the temperature gradient in the reaction system can be reduced by performing the appropriate cooling treatment as described above, so that production with such a short residence time can be realized.

  In the production method of the present invention, it is particularly preferable that the temperature fluctuation (temperature difference between the tank outlet and the return port) is small and the residence time is short. For example, the combination of temperature fluctuation / residence time is preferably within 25 ° C./120 minutes or less, more preferably within 20 ° C./120 minutes or less, and even more preferably within 20 ° C./60 minutes or less. Preferably, it is within 15 ° C./30 minutes or less.

  In the production method of the present invention, the conversion rate of the monomer is preferably 90% or more, more preferably 96% or more, and further preferably 99% or more. If the conversion is less than 90%, there are many residual monomers and the productivity may be reduced. Here, the conversion rate refers to the amount of monomer converted into a polymer at the circulation line outlet (tank inlet) with respect to the amount of monomer added at the monomer supply port. The conversion rate can be obtained by changing the amount of initiator, amount of transfer agent, amount of accelerator, temperature, residence time in various ways, for example, when sodium acrylate is used as a monomer to obtain sodium polyacrylate (PSA). It can be calculated based on the Arrhenius equation from the result of the simulation by the reaction rate analysis. Note that the conversion rate by the above calculation method is as follows when a copolymer such as (meth) acrylic acid (salt) / (meth) acrylic acid ester is produced in a continuous stirred tank reactor (CSTR). , PSA and other homopolymers may be different, but the preferred range of conversion is as described above.

In the production method of the present invention, the circulating fluid in the tank is preferably agitated with a required power Pv for agitation of 0.5 kW / m ³ or more. The required power Pv for stirring is preferably 0.6 to 8.0 kW / m ³ , more preferably 1.0 to 6.0 kW / m ³ . Such power required for stirring can be realized by using the stirring means described in the above section A. By stirring the circulating liquid in the tank with the required power for stirring in such a range, a water-soluble polymer having a narrow molecular weight distribution can be obtained even on an industrial scale production line. If the stirring means described in the above section A is used, the required power Pv for stirring can be made larger than 8.0 kW / m ³ , but the effect obtained is substantially the same as in the case of the above preferable range. In consideration of the characteristics (for example, the cost of electric power and operation costs, and the need to increase the size of the apparatus), it is not necessary to dare to use an excessive Pv. The required stirring power Pv can be calculated, for example, from the Nagata equation described on page 431 of the Chemical Engineering Handbook (Edited by the Chemical Engineering Society, revised 6th edition, Maruzen Co., Ltd.).

  In the above production method, the monomer concentration of the circulating liquid at the tank outlet is preferably 0.3 mol / kg or less, more preferably 0.15 mol / kg or less, and further preferably 0.10. Mole / kg or less. The monomer concentration of the circulating liquid at the tank outlet is preferably as small as possible, and particularly preferably substantially 0 mol / kg. By controlling to such a concentration, the residual monomer of the finally obtained product can be made extremely low. According to the production method of the present invention, such a monomer concentration can be achieved by the tank also functioning as a polymerization vessel.

  In the above production method, the polymerization reaction in the tank and / or the circulation line may be performed under pressure. By performing the polymerization reaction under pressure, the polymerization reaction can be performed at a high temperature. As a result, a water-soluble polymer with little residual monomer can be obtained with very high productivity. The pressure may be controlled, for example, by adjusting the flow rate or temperature of the circulating fluid, or may be controlled using a pressure control means such as a pressurizing pump or a decompressing pump. The pressure in the tank and / or the circulation line is preferably 0.1 MPa to 3.0 MPa, more preferably 0.12 MPa to 1.0 MPa. In addition, the polymerization reaction can be performed under any appropriate atmosphere (for example, under air, under an inert gas atmosphere such as nitrogen or argon, under a reactive gas atmosphere derived from a chain transfer agent or the like).

  In the above production method, the polymerization reaction can be performed in any appropriate pH range. In other words, the polymerization reaction may be performed under acidic conditions, may be performed under neutral conditions, or may be performed under alkaline conditions. For example, when persulfate is used as the polymerization initiator, it is preferably carried out under low pH conditions, and when hydrogen peroxide is used, it is preferably carried out under high pH conditions. For example, when the polymerization reaction is performed in an acidic region, an increase in the viscosity of the aqueous solution in the polymerization reaction system can be suppressed, and a low molecular weight water-soluble polymer can be produced satisfactorily. The pH of the circulating fluid can be adjusted by appropriately using an oxidizing agent or an alkaline agent.

  In the above production method, the supplied monomer is converted into a polymer at a very high conversion rate while circulating through the circulation line. Therefore, the discharged liquid (water-soluble polymer solution) can be recovered by discharging a part of the circulating liquid to the outside of the circulation line while circulating the circulating liquid. Usually, the effluent can be post-treated. In this specification, “post-treatment” means that the water-soluble polymer in the effluent can be suitably used for a predetermined application (for example, a detergent, a water treatment agent, a dispersant). It refers to various treatments performed on the conductive polymer. Hereinafter, typical post-processing will be described in detail.

  In one embodiment, the monomer and, if necessary, the various additives may be supplied to the effluent. By mixing the discharged liquid (water-soluble polymer solution) and the monomer, the polymerization of the residual monomer (and the added monomer) contained in the water-soluble polymer newly proceeds and obtained. The residual monomer contained in the water-soluble polymer can be made extremely low. In one embodiment, mixing (typically agitation) and / or cooling can occur at an appropriate location in the discharge line. The mixing device and the cooler are as described in the above section A.

  In one embodiment, the additive can be an oxidizing agent. By supplying the oxidizing agent, the pH of the effluent is adjusted, and new polymerization of the residual monomer can proceed well. Therefore, the oxidizing agent can be preferably supplied before supplying the monomer. The kind of the oxidizing agent to be supplied can be appropriately selected according to the kind of the polymerization initiator, the components in the discharged liquid, and the like.

  The various post-treatments described above can be performed in appropriate combination.

  The solid content concentration of the discharged liquid at the time when the discharged liquid is recovered from the discharge line (at the time when the polymerization reaction is completed) is preferably 35% by mass or more, more preferably 40 to 70% by mass, and further preferably 45 to 65% by mass. It is. When the solid content concentration is less than 35% by mass, for example, it may be necessary to concentrate the effluent for practical use of the water-soluble polymer. According to the production method of the present invention, the polymerization can be carried out in such a high concentration (high solid content concentration) and in one stage, so that a low molecular weight water-soluble polymer can be obtained efficiently. For example, the above-described concentration step (which was necessary in many cases in the conventional manufacturing method) can be omitted. As a result, the production efficiency and production cost of the water-soluble polymer can be greatly improved. Furthermore, in the conventional method, when the solid content concentration is increased, the viscosity of the reaction solution is significantly increased as the polymerization reaction proceeds, and the weight average molecular weight of the resulting polymer is significantly increased. It was. According to one embodiment of the production method described above, the polymerization reaction is performed under acidic conditions (for example, the pH at 25 ° C. is 1 to 6 and the degree of neutralization is 1 to 25 mol%). In addition, an increase in the viscosity of the reaction solution (circulated liquid and / or discharged liquid) accompanying the progress of the polymerization reaction can be suppressed. As a result, a polymer having a high molecular weight (high solid content concentration) and a low molecular weight can be obtained.

  If necessary, any appropriate alkaline agent is added to the recovered effluent (the target water-soluble polymer solution) to adjust the degree of neutralization (final neutralization degree) to the desired range. obtain. An alkali agent may be used independently according to the objective, and may be used in combination of 2 or more type. The desired degree of final neutralization varies depending on the use of the water-soluble polymer. Therefore, the final neutralization degree can be set in a very wide range of 1 to 100 mol%. For example, when a water-soluble polymer is used as a detergent builder in a weakly acidic detergent or the like that is said to be gentle to the skin, the discharged liquid may be used without being neutralized. The final neutralization degree when used as an acidic polymer is preferably 1 to 75 mol%, more preferably 5 to 70 mol%. Further, for example, when used in a neutral detergent or an alkaline detergent, the discharged liquid may be neutralized with an alkaline agent and neutralized to a degree of neutralization of 90 mol% or more. When used as a neutral to alkaline polymer, the final neutralization degree is preferably 75 to 100 mol%, more preferably 85 to 99 mol%. In addition, when the final neutralization degree exceeds 99 mol%, there is a concern that the discharged liquid (water-soluble polymer solution) may be colored.

  As described above, a water-soluble polymer is produced.

C. Water-soluble polymer and raw material thereof C-1. Water-soluble polymer When the water-soluble polymer obtained above is used as a detergent builder, a dispersant, a scale inhibitor, etc., its weight average molecular weight (Mw) is preferably 1500 to 30000, more preferably. Is 2000 to 20000, more preferably 3500 to 15000, and particularly preferably 4000 to 12000. Moreover, when the said water-soluble polymer is a homopolymer of (meth) acrylic acid (salt), the weight average molecular weight (Mw) becomes like this. Preferably it is 1500-30000, More preferably, it is 2000-12000. Yes, more preferably 2000-10000. By narrowing the molecular weight distribution (Mw / Mn) in such a molecular weight range, more polymers having the same degree of polymerization can be obtained. As a result, for example, the dispersant has a favorable influence on the performance required for each application, such as improvement of dispersibility. Mw / Mn is preferably 7 or less, more preferably 5 or less, still more preferably 3.5 or less, particularly preferably 3.2 or less, and most preferably 2.7 or less.

  Mw / Mn of the water-soluble polymer is preferably 7 or less, preferably 3.5 or less, when the weight average molecular weight (Mw) is preferably 1500 to 30000, more preferably 2000 to 20000. Is more preferable. If Mw / Mn is in such a range, it can be suitably used for applications such as detergent builders, scale inhibitors, inorganic pigment dispersants and the like. Further, Mw / Mn of the water-soluble polymer is preferably 6.5 or less, and preferably 2.9 or less when Mw is preferably 1500 to 30000, more preferably 2000 to 15000. More preferred. When the Mw is preferably 2000 to 12000, the Mw / Mn of the water-soluble polymer is preferably 5 or less, more preferably 2.7 or less.

  The number average molecular weight (Mn), weight average molecular weight (Mw) and Mw / Mn of the polymer can be obtained by GPC (gel permeation chromatography) measurement. Measurement conditions are as follows: (1) As a GPC column, G-3000PWXL (trade name) manufactured by Tosoh Corporation is used. (2) As a mobile phase, 34.5 g of disodium hydrogen phosphate 12 hydrate and 46.2 g of sodium dihydrogen phosphate dihydrate (both of which are reagent-grade) are added pure water to make a total amount of 5000 g, Thereafter, an aqueous solution (solid content: 0.1% by mass) filtered through a 0.45 μm membrane filter is used. (3) As the detector, L-7110 (trade name) manufactured by Hitachi, Ltd. is used, and the detection wavelength is 214 nm. (4) Measurement is performed in the UV measurement mode. (5) The pump is L-6000 manufactured by Hitachi, Ltd., the mobile phase flow rate is 0.5 ml / min, and the temperature is 35 ° C. (6) A calibration curve is prepared using a sodium polyacrylate standard sample manufactured by Soka Kagaku Co., Ltd., and the molecular weight is calculated using analysis software SIC480II data station manufactured by System Instruments Co., Ltd.

  In the present specification, the water-soluble polymer means a polymer having a hydrophilic functional group such as an acid such as carboxylic acid, phosphonic acid or sulfonic acid and a salt thereof, amide, amine or alcohol. Examples of the salt include alkali metal salts such as sodium and potassium; alkaline earth metal salts such as calcium and magnesium; ammonium salts; organic amine salts such as monoethanolamine and triethanolamine. These salts may be used alone or as a mixture of two or more. Preferred forms in the case of a salt are alkali metal salts such as sodium and potassium and ammonium salts, and particularly preferably sodium salts and ammonium salts.

  The water-soluble polymer is also a water-soluble polymer composed of polyacrylic acid and / or a salt thereof having a sulfur atom and / or a phosphorus atom at the terminal, and the peak of the polyacrylic acid and / or the salt thereof. The top molecular weight is in the range of 100 to 50000, and is included in the retention time when the molecular weight obtained from the calibration curve using standard polyacrylic acid soda is 2500 to 7000 with gel permeation chromatography. It is also a water-soluble polymer having an area strength of 38.0% or more with respect to the total area strength of the polyacrylic acid and / or a salt thereof. The water-soluble polymer may be composed of polyacrylic acid having a sulfur atom and / or a phosphorus atom at the end of the main chain of the polymer and / or a salt thereof, and has other components. Also good. Since the sulfur atom and / or phosphorus atom derived from the chain transfer agent capable of controlling the molecular weight of the polymer is introduced at the main chain terminal of the polymer, it has a sulfur atom and / or phosphorus atom at the main chain terminal, so In the case of obtaining a conductive polymer, the polymerization can be accelerated. Moreover, if the addition amount is changed, a water-soluble polymer having a desired molecular weight can be easily obtained.

  The polyacrylic acid and / or the salt thereof has a polymer content of 38.0% or more within a specific molecular weight range. If it is less than 38.0%, excellent clay dispersibility cannot be obtained, and there is a possibility that it cannot be suitably used for various applications such as a builder. More preferably, it is 39.0% or more, more preferably 39.5% or more, most preferably 40.0% or more, and particularly preferably 41.0% or more. Especially, if the amount of the polymer included in the molecular weight range is 41.0% (area%) or more, sufficient clay dispersibility can be expressed.

  The upper limit of the amount of the polymer included in the specific molecular weight range is 100.0%. In the present invention, the amount of the polymer may be 38.0% or more, and the upper limit is not particularly limited, but is preferably 80.0% or less from the viewpoint of productivity. For example, when the amount of the polymer is 100.0%, in order to increase the content, an operation such as dialysis to remove the out-of-range polymer, an operation to prevent the out-of-range polymer from being made, etc. Although it is necessary, by making it 80.0% or less, the above operation can be omitted or simplified, and a polymer can be obtained with high productivity. Further, even within such a range, sufficiently high clay dispersibility can be exhibited. That is, by setting it to 80.0% or less, it can be excellent in both clay dispersibility and polymer productivity. More preferably, it is 70.0% or less as an upper limit, More preferably, it is 65.0% or less.

  The polymer content is an area ratio obtained by gel permeation chromatography (GPC), and [the retention from which the molecular weight obtained from the calibration curve using standard sodium polyacrylate is 2500 is 7000 The area strength of polyacrylic acid and / or its salt in the section included in time] / [total area strength of polyacrylic acid and / or its salt] × 100. When the retention time is less than 2500, the resulting water-soluble polymer has low dispersibility, and when the retention time exceeds 7000, when a metal atom coexists, the metal atom is crosslinked and insolubilized. There is a possibility that it can no longer be suitably used for various applications. As the area ratio, for example, as shown in the conceptual diagram of FIG. 3, the mesh line portion has a retention time from which the molecular weight obtained from the calibration curve using standard sodium polyacrylate is 2500 to 7000. The area strength of the polyacrylic acid and / or salt thereof in the section contained in is shown, and the hatched portion represents the total area strength of the polyacrylic acid and / or salt thereof.

  The measurement conditions for the gel permeation chromatography (GPC) are preferably as described above. The standard curve using standard sodium polyacrylate is the same as the GPC measurement conditions for standard polysodium acrylate having a peak top molecular weight (Mp) of 900 to 47500, etc., and for the polyacrylic acid and / or its salt. It is measured under conditions and represents the relationship between retention time and molecular weight. The area intensity of the polyacrylic acid and / or salt thereof is obtained by dividing the area of the section corresponding to Mp of 2500 to 7000 by the area of the entire section from the calibration curve.

  The water-soluble polymer is not particularly limited as long as it is constituted by polyacrylic acid and / or a salt thereof, and can exhibit the effects of the present invention, and may contain other components. . Examples of the other components include organic / inorganic substances derived from initiators, transfer agents, and the like, residual monomers and addition reaction products derived from residual monomers. As a content rate of the said polyacrylic acid and / or its salt, it is preferable that it is 90 mol or more in 100 mol of water-soluble polymers. If the amount is less than 90 mol, the effects of the present invention may not be sufficiently exhibited. More preferably, it is 95 mol or more, and still more preferably, the water-soluble polymer is entirely composed of polyacrylic acid and / or a salt thereof. Thus, in gel permeation chromatography (GPC), the area intensity of the section included in the retention time of 2500 to 7000 in the molecular weight (Mp) obtained from the calibration curve using standard sodium polyacrylate. Is preferably 38.0% or more based on the total area strength of the polymer, and polyacrylic acid having sulfur and / or phosphorus bonded to the polymer terminal and / or a salt thereof is also preferable in the present invention. One of the forms.

  The polyacrylic acid and / or salt thereof preferably has a clay dispersibility of 0.85 or more. If it is less than 0.85, it may not be suitably used for various applications such as detergents, water treatment agents or dispersants. More preferably, it is 0.88 or more, More preferably, it is 0.90 or more. The polyacrylic acid and / or salt thereof preferably has a number average molecular weight in the range of 2000 to 3000. If the number average molecular weight is less than 2000, dispersibility may be insufficient, and if it exceeds 3000, insolubilization by a polyvalent metal may occur.

C-2. Monomer Any appropriate monomer can be used as the monomer. For example, an unsaturated carboxylic acid monomer is preferable.

The unsaturated carboxylic acid monomer (hereinafter also referred to as monomer (I)) may be any monomer having a polymerizable unsaturated group and a group capable of forming a carbanion. Is a compound represented by the following general formula (1).

^Wherein, R 1, ^{R 2} and ^{R 3} are the same or different, a hydrogen atom, a methyl group, or _- represents a ^{_{(CH 2) z1 COOM 2,}} z1 represents the number of 0 to 3. - _{(CH 2)} z1 COOM ² may, -COOM ¹ or another _{- (CH} 2) may form a z1 COOM ² and anhydride. M ¹ and M ² are the same or different and each represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group (organic ammonium group).

The metal atom in M ¹ and M ² of the general formula (1) is a monovalent metal atom such as an alkali metal atom such as lithium, sodium or potassium; a divalent metal such as an alkaline earth metal atom such as calcium or magnesium; A trivalent metal atom such as aluminum or iron is preferred. Moreover, as an organic amine group, alkanolamine groups, such as an ethanolamine group, a diethanolamine group, and a triethanolamine group, and a triethylamine group are suitable. Further, the organic amine group may be an ammonium group.

  As the monomer (I), an unsaturated monocarboxylic acid-based monomer, an unsaturated dicarboxylic acid-based monomer, and the like are preferable. Any monomer that has one saturated group and one group capable of forming a carbanion may be used, for example, acrylic acid, methacrylic acid, crotonic acid, α-hydroxyacrylic acid, etc .; these monovalent metal salts, 2 Preferred are valent metal salts, ammonium salts and organic amine salts. The unsaturated dicarboxylic acid-based monomer may be any monomer having one unsaturated group and two groups capable of forming a carbanion in the molecule, such as maleic acid, itaconic acid, citraconic acid, Fumaric acid and the like, monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof, or anhydrides thereof are preferable.

  In addition to these, the monomer (I) is a half ester of an unsaturated dicarboxylic acid monomer and an alcohol having 1 to 22 carbon atoms, an unsaturated dicarboxylic acid and an alcohol having 1 to 22 carbon atoms. A half amide with an amine, a half ester of an unsaturated dicarboxylic acid monomer and a glycol having 2 to 4 carbon atoms, a half amide of maleamic acid and a glycol having 2 to 4 carbon atoms, or the like can also be used. As the monomer (I), one or more of the above-exemplified examples can be suitably used. Among them, (meth) acrylic acid (salt), from the viewpoint of high polymerizability and versatility, Maleic acid (salt), maleic anhydride, itaconic acid (salt), and α-hydroxyacrylic acid (salt) are preferable, and (meth) acrylic acid and maleic acid (salt) are more preferable. More preferred is (meth) acrylic acid (salt). In addition, (meth) acrylic acid (salt) refers to (meth) acrylic acid and a partial or completely neutralized salt such as monovalent metal salt, divalent metal salt, ammonium salt or organic amine salt thereof. .

  The monomer component capable of producing the water-soluble polymer can be copolymerized with other monomers (the unsaturated carboxylic acid monomer (monomer (I)) other than the monomer (I). Monomer (hereinafter also referred to as monomer (II)) can be preferably used. The monomer (II) may be any monomer copolymerizable with the monomer (I), such as vinyl sulfonic acid, allyl sulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, isoprene. Monoethylenically unsaturated monomers having a sulfonic acid group such as sulfonic acid, 2-acrylamidomethylpropanesulfonic acid, styrenesulfonic acid, and 2-sulfoethyl methacrylate, and monovalent metal salts, divalent metal salts thereof, Partially or completely neutralized salts such as ammonium salts and organic amine salts; 3-methyl-2-buten-1-ol (also simply referred to as prenol), 3-methyl-3-buten-1-ol (simply simply isoprenol) Also called unsaturated hydrocarbons containing hydroxyl groups such as (meth) allyl alcohol, isoprenol and allyl alcohol. It was added Sid unsaturated polyalkylene glycol monomer, and the like.

  As said monomer (II), a radically polymerizable monomer can also be used conveniently. The radical polymerizable monomer is not particularly limited as long as it is a radical polymerizable monomer. For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic Hexyl acid, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, ( Mono (meth) acrylates such as ethyl aminoethyl acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, allyl (meth) acrylate; triethylene glycol di (meth) acrylate, tetraethylene Glycol di (meth) acrylate, pentylglyco Rudi (meth) acrylate, dipropylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, etc. (Meth) acrylates such as polyvalent (meth) acrylates; alkoxy polyalkylene glycol (meth) acrylate, polyalkylene glycol (meth) acrylate, α- (hydroxyalkyl) acrylic acid (salt), α- (hydroxy) (Polyalkyleneoxymethyl) acrylic acid (salt).

  Aromatic monomers such as styrene and α-methylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, and hydroxybutyl vinyl ether; N-vinyl Monomers having nitrogen-containing functional groups such as pyrrolidone and acryloylmorpholine; Nitrile group-containing monomers such as (meth) acrylonitrile; Amide monomers such as (meth) acrylamide and N-methylolacrylamide; Itaconic acid, Carboxyl group-containing monomers such as crotonic acid, maleic anhydride and maleic acid; Hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate; Epoxy group-containing monomers such as glycidyl (meth) acrylate Etc. are preferred And the like as the body. As said monomer (II), 1 type (s) or 2 or more types can be selected suitably and used.

  The blending amount of the monomer (I) is in the range of 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 90 to 100 mol%, based on the total amount of monomers. When the amount of monomer (I) is 50 mol% or more, in many cases, water solubility can be widely expressed, which is preferable. On the other hand, about an upper limit, 100 mol%, ie, the whole quantity (meth) acrylic acid (salt) may be sufficient. Furthermore, when using together acrylic acid (salt) and methacrylic acid (salt) as a monomer (I), the compounding quantity of this (meth) acrylic acid (salt) is preferable with respect to the monomer whole quantity. Is used in the range of 50 mol% or less, more preferably 0.5 to 40 mol%, still more preferably 1 to 30 mol%.

  The monomer (I) may be added in the form of a solution (preferably an aqueous solution) of the monomer (I) after being dissolved in a solvent described later, preferably water. The concentration when used as a monomer (I) solution (preferably an aqueous solution) is 30 to 75% by mass, preferably 35 to 70% by mass, and more preferably 40 to 65% by mass. When the concentration of the monomer (I) solution is within this range, a product with a good concentration can be obtained, which is preferable in terms of transportation and storage.

  It is preferable that the compounding quantity of the said monomer (II) is 0-50 mol% with respect to the monomer whole quantity. More preferably, it is 0-30 mol%, More preferably, it is 0-10 mol%. When the blending amount of the (II) is 50 mol% or less, the physical properties of the monomer (II) alone or in cooperation with the monomer (I) can be expressed as a polymer while maintaining water solubility. . On the other hand, the lower limit of the monomer (II) is 0 mol%. That is, any of a homopolymer (copolymer) or a copolymer (copolymer) based on the monomer (I) component may be used.

  The monomer (II) may be added in the form of a solution (preferably an aqueous solution) of the monomer (II) after being dissolved in a solvent described later, preferably water. The concentration when used as a monomer (II) solution (preferably an aqueous solution) is 10 to 100% by mass, preferably 20 to 95% by mass, more preferably 30 to 90% by mass. When the concentration of the monomer (II) solution is 10% by mass or more, a product with a good concentration can be obtained, which is preferable in terms of transportation and storage. On the other hand, the upper limit is not particularly limited, and may be 100% by mass (that is, the total amount) of monomer (II) (that is, no solvent).

  Examples of the solvent include water; monohydric alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, pentanol, hexanol, cyclohexanol, methylcyclohexanol, and benzyl alcohol; ethylene glycol, propylene glycol, ethylene glycol diacetate, Ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol diacetate, propylene glycol monomethyl Ether, propire Polyhydric alcohols such as glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate and glycerin and derivatives thereof; Amides such as dimethylformaldehyde; Ethers such as diethyl ether and dioxane; Acetone, methyl ethyl ketone, diisobutyl ketone and diisopropyl Ketone solvents such as ketone, diethyl ketone, cyclohexanone, methyl isobutyl ketone; ester solvents such as methyl acetoacetate, ethyl acetoacetate, methyl benzoate, ethyl benzoate, ethyl acetate, butyl acetate; benzene, toluene, xylene, cyclohexane One type or two or more types of hydrocarbon solvents such as can be appropriately selected and used.

  The solvent is preferably an aqueous solvent such as water, alcohol, glycol, glycerin or polyethylene glycol. More preferably, the aqueous solvent uses water and one or more kinds other than water. When a solvent other than water is used, the boiling point or solubility can be adjusted. The mixing ratio of water and a solvent other than water may be appropriately set in consideration of the solubility of the polymer, the reactivity with the raw material, and the like, and is usually preferably 10% by mass or less.

  The amount of the solvent used is in the range of 40 to 200 mass%, preferably 45 to 180 mass%, more preferably 50 to 150 mass%, based on the total amount of monomers. When the amount of the solvent used is less than 40% by mass, the molecular weight becomes high. On the other hand, when the amount of the solvent used exceeds 200% by mass, the concentration of the produced water-soluble polymer is low. In some cases, it is not preferable because solvent removal is required. A part of the solvent can be charged into the production apparatus at the initial stage of polymerization as required. A part of the solvent may be suitably added to the reaction system alone during polymerization, for example, from the supply port of other components. In addition, monomer components, initiators, other additives, and the like may be appropriately added to the reaction system during the polymerization together with these components in the form of being dissolved in a solvent in advance.

  Although the usage-amount ratio of a solvent and a monomer is not specifically limited, It is preferable that a monomer whole quantity shall be 200 mass parts or less with respect to 100 mass parts of solvents. More preferably, it is 180 mass parts or less, More preferably, it is 160 mass parts or less.

  When the monomers (I) and / or (II) are copolymerized, the addition time may be controlled according to the polymerizability of each monomer. For example, when using a monomer having low polymerizability, the addition time may be shortened. Further, a part or the whole amount of the monomer may be charged in the production apparatus in advance.

C-3. Polymerization initiator As the polymerization initiator that can be used in the production method of the present invention, a redox initiator, an azo-based initiator, an organic peroxide, a photoinitiator and the like are suitable. Specifically, persulfates such as sodium persulfate, ammonium persulfate, and potassium persulfate; hydrogen peroxide; 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis (4- Cyano compounds such as cyanovaleric acid), azobisisobutylnitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile); benzoyl peroxide, lauroyl peroxide, peracetic acid, persuccinic acid, di Organic peroxides such as -t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide and the like can be mentioned. These may be only one type or two or more types. Among these, redox initiators, azo initiators, and organic peroxides are preferable. Specifically, persulfate, hydrogen peroxide, organic peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride is preferable, and persulfate, hydrogen peroxide, 2,2′-azobis. (2-Amidinopropane) dihydrochloride is more preferable, and persulfate and hydrogen peroxide are still more preferable.

  As said polymerization initiator, you may use the metal single-piece | unit, salt, and / or complex which have the metal which has a several oxidation number as a structural component. Metals having a plurality of oxidation numbers include, for example, iron divalent and trivalent, copper monovalent and divalent, cobalt divalent and trivalent, chromium divalent, trivalent and hexavalent, It has a plurality of oxidation numbers. If there is a plurality of oxidation numbers, the type of the metal is not limited if it is used to promote the reaction, but considering that the reaction system is not complicated, it is a metal component having two types of oxidation numbers. More preferred are simple metals, salts and / or complexes. Examples of the ligand of the metal complex include water (aquo complex), ammonia (ammonium complex), ethylenediamine, cyan (cyano complex), hydroxyl group (hydroxy complex), halogen (halogeno complex), cyclic ether, pyridine and the like. Cyclic amine, fullerene, porphyrin, cyclopentadiene (metallocene) and the like are preferable.

As the metal simple substance, salt and / or complex containing the metal having a plurality of oxidation numbers as a constituent, a polyvalent metal compound or simple substance is preferable. Specifically, vanadium oxytrichloride, vanadium trichloride, vanadyl oxalate, vanadyl sulfate, vanadic acid anhydride, ammonium metavanadate, ammonium sulfate hypo-nosed Das _{[(NH 4) 2 SO 4} · VSO 4 · 6H 2 O], Ammonium sulfate vanadas [(NH ₄ ) V (SO ₄ ) ₂ · 12H ₂ O], copper (II) acetate, copper (II) bromide, copper (II) acetyl acetate, cupric ammonium chloride, ammonium copper chloride, Copper carbonate, copper chloride (II), copper citrate (II), copper formate (II), copper hydroxide (II), copper nitrate, copper naphthenate, copper oleate (II), copper maleate, copper phosphate , Copper (II) sulfate, cuprous chloride, copper (I) cyanide, copper iodide, copper (I) oxide, copper thiocyanate, iron acetyl acetonate, ammonium iron citrate, Ferric ammonium oxalate, ammonium iron sulfate (Mole salt), ferric ammonium sulfate, iron citrate, iron fumarate, iron maleate, ferrous lactate, ferric nitrate, iron pentacarbonyl, phosphoric acid ferric acid Water-soluble polyvalent metal salts such as ferric iron and ferric pyrophosphate; polyvalent metal oxides such as vanadium pentoxide, copper (II) oxide, ferrous oxide and ferric oxide; iron (III) sulfide, It is preferable that it is 1 type, or 2 or more types, such as polyvalent metal sulfides, such as iron (II) sulfide and copper sulfide; copper powder, iron powder, etc. These may be in the form of hydrates. In view of availability and economy, sulfates, halides, and water-soluble complexes are more preferable, and sulfates and water-soluble complexes are more preferable. The metal simple substance, salt and / or complex containing the metal having a plurality of oxidation numbers as a constituent component is preferably made into a circulation line from the above-mentioned polymerization initiator supply port, and the arrangement of the polymerization initiator supply port The number of installations is as described above.

  As said polymerization initiator, you may combine said thing. For example, persulfates and sulfites, persulfates and hydrogen peroxide, sulfites and oxygen, polyvalent metal ions and one or more of the above initiators (eg, iron and hydrogen peroxide or persulfate) (Salt system, iron, persulfate, and sulfite system), hydrogen peroxide and thiouric acid, and a reducing organic compound such as L-ascorbic acid or a salt thereof. Of these, combinations of persulfate and sulfite, persulfate and hydrogen peroxide, polyvalent metal ions, persulfate and sulfite are preferred. More preferred are polyvalent metal ions, persulfates and sulfites. Specific examples of the polyvalent metal ions include compounds mentioned in the heavy metal-containing compounds described below, for example, water-soluble polyvalent metal salts such as vanadium oxytrichloride, polyvalent metal oxides such as vanadium pentoxide, and sulfides. Examples thereof include polyvalent metal sulfides such as iron (III), complexes containing polyvalent metals such as ammonium iron sulfate (Mole salt), and simple metals such as copper powder. Of these, ammonium iron sulfate (Mole salt) is preferred. That is, as the polymerization initiator, a complex containing a polyvalent metal, a persulfate and a sulfite system are more preferable, and an ammonium iron sulfate (mole salt), a persulfate and a sulfite system are more preferable. Specifically, a form in which ammonium iron sulfate (Mole salt) is combined with sodium persulfate and sodium bisulfite is preferable.

  In particular, by using one or more persulfates and bisulfites in combination, a low molecular weight water-soluble polymer having excellent dispersibility and chelate ability can be obtained, which is preferable. By adding bisulfite to the initiator system in addition to persulfate, the resulting water-soluble polymer can be prevented from becoming too high in molecular weight, and the molecular weight of the polymer can be adjusted. In addition, when a single metal, a salt and / or a complex containing a metal having a plurality of oxidation numbers as a constituent component is combined, there is an advantage that the reaction rate can be greatly improved. For example, when a mole salt is used in combination, the molecular weight of the obtained water-soluble polymer can be easily defined, deoxygenated in bisulfite, and at the same time, a water-soluble polymer having a desired molecular weight can be obtained. it can. In addition, the polymerization rate of the water-soluble polymer can be increased. For example, when producing polyacrylic acid and / or a salt thereof as the water-soluble polymer, 90% or more of acrylic acid and / or a salt thereof in 30 seconds. Can be converted to polyacrylic acid and / or its salts.

  Specific examples of the persulfate include sodium persulfate (sodium peroxodisulfate), potassium persulfate, and ammonium persulfate as described above. Sodium persulfate is preferred. Specific examples of the bisulfite include sodium bisulfite, potassium bisulfite, and ammonium bisulfite. Further, sulfite, pyrosulfite, etc. may be used instead of bisulfite.

  The addition ratio of persulfate and bisulfite is 0.5 to 5 parts by mass, preferably 1 to 4 parts by mass, and more preferably 1.25 to 3 parts by mass with respect to 1 part by mass of persulfate. Within the range of parts by mass. By using 0.5 parts by mass or more of bisulfite with respect to 1 part by mass of persulfate, it is possible to obtain a sufficient effect of bisulfite and to keep the weight average molecular weight of the water-soluble polymer sufficiently low. it can. On the other hand, when the amount of bisulfite is 5 parts by mass or less with respect to 1 part by mass of persulfate, a sufficient bisulfite addition effect can be obtained, and excessive supply of bisulfite can be suppressed. For this reason, generation | occurrence | production of sulfurous acid gas by an excessive bisulfite being decomposed | disassembled by a polymerization reaction system can be suppressed. Moreover, the performance degradation of the water-soluble polymer obtained and impurity precipitation at the time of low-temperature holding can be prevented effectively, and it does not cause impurity precipitation at the time of low-temperature holding, which is preferable. The addition ratio in the case of using a simple metal, a salt and / or a complex containing a metal having a plurality of oxidation numbers as a constituent component is preferably 20% by mass or less with respect to 100% by mass of persulfate. When it exceeds 20% by mass, the effect of promoting the reaction and the like is maintained, but there is a possibility that the economy is inferior. Further, depending on the metal salt or complex to be added, it may be colored depending on conditions such as pH, and depending on the use of the water-soluble polymer, there is a possibility that an undesirable result may be brought about. More preferably, it is 0.2 mass% or less, More preferably, it is 0.02 mass% or less.

  The amount of persulfate and bisulfite added is preferably 2 to 20 g, more preferably 4 to 15 g, and still more preferably 6 to the total amount of persulfate and bisulfite per mole of monomer. 12 g, particularly preferably 6 to 9 g. In the present invention, persulfate and bisulfite may be added in such a low addition amount range, and the generation of impurities can be reduced. Furthermore, it is possible to prevent deterioration of the performance of the obtained water-soluble polymer and precipitation of impurities during holding at a low temperature. When the addition amount of the above-mentioned polymerization initiator persulfate and bisulfite is within the range of 2 to 20 g, a polymer having a good molecular weight can be efficiently produced without adversely affecting the purity of the resulting water-soluble polymer. Can be obtained. The amount of addition in the case of using a single metal, a salt and / or a complex containing a metal having a plurality of oxidation numbers as a constituent component is 1.5% by mass or less with respect to 100% by mass of the monomer. Is preferred. When it exceeds 1.5 mass%, the effect of promoting the reaction and the like is maintained, but there is a possibility that the economy is inferior. Further, depending on the metal salt or complex to be added, it may be colored depending on conditions such as pH, and depending on the use of the water-soluble polymer, there is a possibility that an undesirable result may be brought about. More preferably, it is 0.015 mass% or less, More preferably, it is 0.0015 mass% or less.

  The persulfate may be dissolved in the aqueous solvent and added in the form of a persulfate solution (preferably an aqueous solution). The concentration when used as the persulfate solution (preferably an aqueous solution) is 1 to 35% by mass, preferably 5 to 35% by mass, and more preferably 10 to 30% by mass. Here, when the concentration of the persulfate solution is less than 1% by mass, the concentration of the product decreases, and transportation and storage become complicated. On the other hand, when the concentration of the persulfate solution exceeds 35% by mass, the persulfate may be precipitated.

  The addition completion time of the persulfate (solution) during the polymerization is 1 to 30 minutes, preferably 1 to 20 minutes, more preferably 1 to 15 minutes than the addition completion time of the monomer (I) (solution). Delay. Thereby, the amount of the monomer component remaining after the completion of the polymerization can be reduced, and impurities caused by the remaining monomer can be significantly reduced.

  Here, when the addition end time of the persulfate (solution) can be delayed by less than 1 minute from the addition end time of the monomer (I) (solution), May remain. In such cases, the end of the addition of the persulfate (solution) and the end of the addition of the monomer (I) (solution) are the same, or the end of the addition of the persulfate (solution) is simpler. The case where it is earlier than the end of addition of the body (I) (solution) is included. In such a case, it is difficult to effectively and effectively suppress the formation of impurities. On the other hand, if the end time of addition of persulfate (solution) is more than 30 minutes later than the end time of addition of monomer (I) (solution), the persulfate or its decomposition product remains after the end of polymerization. In addition, impurities may be formed. Also, use the above-mentioned oxidizing agents such as oxygen, ozone, hydrogen peroxide, persulfate, perchlorate, permanganate, dichromate, bromate, nitric acid (salt), hypochlorite, etc. The same effect can also be achieved.

  The bisulfite may be dissolved in the aqueous solvent and added in the form of a bisulfite solution (preferably an aqueous solution). The concentration when used as the bisulfite solution (preferably an aqueous solution) is 10 to 40% by mass, preferably 20 to 40% by mass, and more preferably 30 to 40% by mass. By setting the concentration of the bisulfite solution within the above range, a product having a sufficient concentration can be obtained without fear of precipitation of bisulfite, which is preferable for transportation and storage.

  Further, in bisulfite, the molecular weight at the initial stage of polymerization greatly affects the final molecular weight. Therefore, in order to reduce the initial molecular weight, it can be adjusted by adding 5 to 20% by mass of bisulfite or a solution thereof within 60 minutes, preferably within 30 minutes, more preferably within 10 minutes from the start of polymerization. In particular, it is effective when the polymerization is started from room temperature.

  Moreover, about the addition time of a bisulfite or its solution among the addition components in the case of superposition | polymerization, it is 1 to 30 minutes from the completion of addition of monomer (I) or its solution, Preferably it is 1 to 20 minutes, Preferably, by completing the addition for 1 to 15 minutes, it is possible to reduce the amount of bisulfite after the completion of polymerization, and effectively and effectively suppress the generation of sulfurous acid gas and the formation of impurities by the bisulfite. Can do. For this reason, after the polymerization is completed, impurities formed by dissolving the sulfurous acid gas in the gas phase in the liquid phase can be significantly reduced. When bisulfite remains after the completion of the polymerization, impurities are generated, leading to deterioration of the performance of the polymer and precipitation of impurities when kept at a low temperature. Therefore, it is more desirable that the initiator containing bisulfite is consumed and does not remain at the end of the polymerization.

  Here, when the addition end time of the bisulfite (solution) can be advanced by less than 1 minute from the addition end time of the monomer (I) (solution), the bisulfite remains after the end of the polymerization. There is a case. In such a case, the end of addition of bisulfite or a solution thereof and the end of addition of monomer (I) (solution) are the same, or the end of addition of bisulfite (solution) is more I) The case where it is later than the end of the addition of (solution) is included. In such a case, it becomes difficult to effectively and effectively suppress the generation of sulfurous acid gas and the formation of impurities, which may adversely affect the thermal stability of the polymer from which the remaining initiator is obtained. On the other hand, if the addition end time of bisulfite or its solution is more than 30 minutes earlier than the addition end time of monomer (I) (solution), the bisulfite has been consumed by the end of the polymerization. ing. For this reason, there exists a possibility of causing the increase in molecular weight. In addition, the addition rate of bisulfite during polymerization is faster than the addition rate of monomer (I) (solution) and is added in a short amount of time, so impurities and sulfite gas are added during this addition period. May occur frequently.

  Moreover, in this invention, it is also preferable to use together 1 type, or 2 or more types of persulfate and hydrogen peroxide as a polymerization initiator. In some cases, a chain transfer agent or a polyvalent metal ion may be used (wherein the polyvalent metal ion serves as a decomposition accelerator for the polymerization initiator), and both of these may be used simultaneously.

  The amount of hydrogen peroxide added is preferably 2.0 to 10.0 g, more preferably 3.0 to 8.0 g, with respect to 1 mol of the monomer. When the amount of hydrogen peroxide added is 2.0 g or more, a (meth) acrylic acid (salt) -based polymer having a sufficiently low polymerization average molecular weight can be obtained. Further, when the addition amount is 10.0 g or less, there is no adverse effect due to the remaining hydrogen peroxide, and a sufficiently effective hydrogen peroxide effect can be obtained. The amount of the persulfate added is preferably 1.0 to 5.0 g and more preferably 2.0 to 4.0 g with respect to 1 mol of the monomer. When the amount of persulfate added is 1.0 g or more, a (meth) acrylic acid (salt) polymer having a sufficiently low molecular weight can be obtained, and when the amount added is 5.0 g or less (meta) ) A sufficiently effective persulfate effect can be obtained without degrading the purity of the acrylic acid (salt) polymer.

  The addition ratio of hydrogen peroxide and persulfate is preferably 0.1 to 5.0 persulfate when the weight of hydrogen peroxide is 1 by weight. More preferably, it is -3.0. When the weight ratio of persulfate is 0.1 or more, the weight average molecular weight of the resulting (meth) acrylic acid (salt) -based polymer can be kept sufficiently low, and if it is 5.0 or less, the effect of adding persulfate Can be sufficiently obtained.

  In the present invention, other initiators may be appropriately used as necessary as long as the effects of the present invention are not adversely affected. In the present invention, the combination of the above-mentioned persulfate and bisulfite is preferably used as the initiator system, but is not particularly limited to this combination. That is, as long as the effects of the present invention are exhibited, the above-described initiator may be used, other initiators may be used, and other initiators may be used in addition to the above-described initiators. Also good. Examples of other initiators include 2,2′-azobis (2-amidinopropane) hydrochloride, 4,4′-azobis-4-cyanoparellinic acid, azobisisobutyronitrile, 2,2′-azobis ( Azo compounds such as 4-methoxy-2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc. Organic peroxides and hydrogen peroxide are mentioned.

  The other initiator may be added in the form of an aqueous solution after being dissolved in the aqueous solvent. The concentration in the case of using as an aqueous solution may be a range that does not impair the effects of the present invention, and is usually appropriately determined based on the same level as the concentration of the above-described persulfate or bisulfite solution.

C-4. Chain transfer agent The chain transfer agent is not particularly limited. Sulfurous acid (salt), hydrogen sulfite (salt), pyrosulfurous acid (salt), phosphorous acid (salt), hypophosphorous acid (salt), thioglycolic acid Octyl thioglycolate, thiopropionic acid, octyl thiopropionate, n-dodecyl mercaptan, t-dodecyl mercaptan, ethylene glycol dithioglycolate, ethylene glycol dithiopropionate, 1,4-butanediol thioglycolate, trimethylol Propane trithioglycolate, trimethylolpropane trithiopropionate, pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, dipentaerythritol hexakisthioglycolate, dipentaerythritol hexakisthio Mercapto group-containing compounds such as propionate, butanethiol, octanethiol, decanethiol, hexadecanethiol, octadecanethiol, cyclohexyl mercaptan, thiophenol, mercaptoethanol, thioglycerol, thiomalic acid, 2-mercaptoethanesulfonic acid and the like, Secondary alcohols such as isopropanol and glycerin can be used.

C-5. Alkaline agent As an alkali agent (also referred to as pH adjuster or neutralizer) for adjusting the pH of the reaction solution during the polymerization or neutralizing the monomer, sodium hydroxide, potassium hydroxide And alkali metal hydroxides such as calcium hydroxide and magnesium hydroxide, and organic amine salts such as ammonia, monoethanolamine and triethanolamine. These may be used alone or in combination of two or more. Among these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide and ammonia are preferable, and sodium hydroxide and ammonia are more preferable.

  The degree of neutralization during the polymerization is 1 to 25 mol%, but when the monomer used for the polymerization is only the monomer (I), it is preferably 2 to 15 mol%, more preferably 3 to 10 mol%. Is within the range. When the monomer used for the polymerization contains the monomer (II) in addition to the monomer (I), a part or all of the monomer (II) can be initially charged. However, the degree of neutralization during polymerization at this time is preferably in the range of 1 to 25 mol%, more preferably 3 to 10 mol%. If the degree of neutralization during polymerization is within such a range, even if only the monomer (I) is used, the monomer (I) and the monomer (II) may be copolymerized. However, the best polymerization or copolymerization is possible. Moreover, the viscosity of the aqueous solution of the polymerization reaction system does not increase, and a low molecular weight polymer can be produced satisfactorily. In addition, since the polymerization reaction can proceed under a higher concentration condition than before, the production efficiency can be significantly increased. When the degree of neutralization during the polymerization is 1 mol% or more, the amount of sulfurous acid gas generated can be favorably suppressed, and the molecular weight of the resulting polymer can be sufficiently low, which is preferable. In addition, when the degree of neutralization during polymerization is 25 mol% or less, sufficient bisulfite chain transfer efficiency can be obtained, so that the molecular weight of the resulting polymer can be kept sufficiently low, and polymerization proceeds. Accordingly, an increase in the viscosity of the aqueous solution of the polymerization reaction system can be suppressed, and a low molecular weight polymer can be obtained without increasing the molecular weight of the obtained polymer more than necessary. Furthermore, the effect by the said neutralization degree reduction can fully be exhibited, and an impurity can be reduced.

  The neutralization method here is not particularly limited. As the neutralizing agent, for example, an alkaline monomer (I) component such as sodium (meth) acrylate may be used. In addition, alkali metal hydroxides such as sodium hydroxide may be used, or these may be used in combination. Moreover, the addition form of the neutralizing agent at the time of neutralization may be solid, or may be an aqueous solution dissolved in an appropriate solvent, preferably water. The concentration of the aqueous solution when the aqueous solution is used is preferably 10 to 60% by mass, more preferably 20 to 55% by mass, and still more preferably 30 to 50% by mass. When the concentration of the aqueous solution is 10% by mass or more, a product having a good concentration can be obtained, which is preferable for transportation and storage. On the other hand, at 60% by mass or less, there is no fear of precipitation and viscosity increase, and liquid feeding and liquid-liquid mixing are easy and preferable.

C-6. Oxidizing agent As the oxidizing agent, oxygen, ozone, hydrogen peroxide, persulfate, perchlorate, permanganate, dichromate, bromate, nitric acid (salt), hypochlorite, etc. Is preferred. The oxidizing agent can be selected depending on the type of initiator, the corrosiveness to the apparatus, and the components remaining in the resulting water-soluble polymer. Among them, oxygen, ozone, hydrogen peroxide, and persulfate are preferable.

C-7. Other Additives As other additives that can be used in the polymerization reaction system when the above monomers are polymerized in an aqueous solution, an appropriate amount of an appropriate additive is added as long as the effects of the present invention are not affected. be able to. For example, it is preferable to use a heavy metal-containing compound, an organic peroxide, hydrogen peroxide (H ₂ O ₂ ) and a metal salt. By using such an additive, the reaction can be accelerated, and it is preferable to add them from the viewpoint of production efficiency. As said heavy metal containing compound, the thing as described in the metal simple substance, salt, and / or complex which uses the metal which has several oxidation number mentioned above as a structural component can be used as an additive, for example.

  Since it is desirable that the heavy metal ion concentration of the water-soluble polymer obtained in the present invention is 0.05 to 10 ppm, it is desirable to add an appropriate amount of the heavy metal-containing compound as necessary. Furthermore, in the present invention, when a SUS (stainless steel) container, a stirrer, or the like is used, an appropriate amount of heavy metal ions, particularly iron ions, as defined above is used in the material of the container or the like under the production conditions of the present invention. This is advantageous in terms of cost-effectiveness because it is eluted (supplied) in a reaction solution from SUS. In the production method of the present invention, when such a reaction apparatus such as a reaction vessel made of SUS or a stirring blade is used, the same operational effects as in the case of adding the heavy metal-containing compound can be obtained. Although there is no problem even with an existing reaction vessel made of steel or copper alloy, there is a possibility that a lot of heavy metal ions are eluted. In such a case, since it is colored with heavy metal, an operation for removing such heavy metal ions is required, which is uneconomical. Moreover, there is no problem even if the reaction vessel is glass-lined or the like, and a heavy metal-containing compound may be used if necessary.

D. Use of Water-Soluble Polymer The present invention is also a detergent, water treatment agent or dispersant containing a water-soluble polymer. That is, in gel permeation chromatography (GPC), the area intensity of the section included in the retention time of 2500 and the retention time of 7000 in the molecular weight (Mp) obtained from the calibration curve using standard polyacrylic acid soda, Polyacrylic acid and / or salt thereof having sulfur and / or phosphorus bonded to the polymer terminal, which is 38.0% or more with respect to the area strength of the whole polymer, and 0.85 in the clay dispersibility test. Detergents, detergent compositions, water treatment agents and / or pigment dispersants that exhibit the above dispersibility and have a number average molecular weight (Mn) in the range of 2000 to 3000 are also preferred forms of the present invention. One.

  The water-soluble polymer may be a water-soluble polymer produced by the production method of the present invention, or may be produced by other production methods. Moreover, the said cleaning composition means the additive for cleaning agents, a cleaning agent, the builder for detergents (detergent builder), and a detergent. The detergent builder exhibits an action for preventing dirt from reattaching to the clothes being washed. When the water-soluble polymer prevents the reattachment of dirt, it removes polyvalent metal ions in the system by the carboxyl group, and it works to make the cleaning component work well, and when it has a hydrophobic terminal structure, it has an affinity for dirt. In the case of having a lowering action or a hydrophilic terminal structure, it is preferable that the dirt dispersing action is sufficiently exerted.

  The detergent builder can be suitably used as a builder for liquid detergents because it has excellent compatibility with surfactants and the resulting detergent becomes a highly concentrated liquid detergent. By being excellent in compatibility with the surfactant, transparency when used in a liquid detergent is improved, and the problem of separation of the liquid detergent caused by turbidity can be prevented. Moreover, it can be set as a highly concentrated liquid detergent by being excellent in compatibility, and the washing | cleaning capability of a liquid detergent can be improved.

  The blending ratio of the liquid detergent builder is usually preferably 0.1 to 20% by mass with respect to 100% by mass of the liquid detergent. More preferably, it is 0.2 mass% or more and 15 mass% or less, More preferably, it is 0.3 mass% or more, 10 mass% or less, More preferably, it is 0.4 mass% or more, 8 mass% Or less, and particularly preferably 0.5% by mass or more and 5% by mass or less. If the blending ratio of the builder for liquid detergent is less than 0.1% by mass, sufficient detergent performance may not be exhibited, and if it exceeds 20% by mass, the economy may be lowered.

  The water content contained in the liquid detergent is usually preferably 0.1 to 75% by mass with respect to 100% by mass of the liquid detergent. More preferably, it is 0.2 mass% or more and 70 mass% or less, More preferably, it is 0.5 mass% or more and 65 mass% or less, Especially preferably, it is 0.7 mass% or more, 60 mass% Or less, more preferably 1% by mass or more and 55% by mass or less, and most preferably 1.5% by mass or more and 50% by mass or less.

  The liquid detergent preferably has a kaolin turbidity of 200 mg / L or less. More preferably, it is 150 mg / L or less, More preferably, it is 120 mg / L or less, Especially preferably, it is 100 mg / L or less, Most preferably, it is 50 mg / L or less. Further, the change (difference) in kaolin turbidity between when the water-soluble polymer of the present invention is added to the liquid detergent and when it is not added is preferably 500 mg / L or less. More preferably, it is 400 mg / L or less, More preferably, it is 300 mg / L or less, Especially preferably, it is 200 mg / L or less, Most preferably, it is 100 mg / L or less. Kaolin turbidity can be measured, for example, by the following method: A sample (liquid detergent) uniformly stirred into a 50 mm square cell having a thickness of 10 mm is charged, air bubbles are removed, and then NDH2000 manufactured by Nippon Denshoku Co., Ltd. is used. Turbidity (kaolin turbidity: mg / L) at 25 ° C. is measured using (trade name, turbidimeter).

  The above-mentioned detergent builder is excellent in re-contamination prevention ability, and is a detergent builder with excellent stability and extremely high quality agent performance that is less likely to cause performance degradation when stored for a long period of time and precipitation of impurities when held at low temperatures. be able to. As other composition components and blending ratios other than the water-soluble polymer in the detergent builder, various components that can be used in a normal detergent builder, and based on the blending ratio, the range does not impair the effects of the present invention. It can be used as appropriate.

  The detergent may be a powder detergent or a liquid detergent. In addition to the water-soluble polymer, additives generally used in detergents can be used for the detergent. Examples of the additive include surfactants, alkali builders, chelate builders, re-deposition to prevent re-deposition of contaminants such as polycarboxylates such as polyacrylates and polyacrylate / malate copolymers, and sodium carboxymethylcellulose. Anti-fouling agents such as benzotriazole and ethylene-thiourea, soil release agents, color transfer inhibitors, softeners, alkaline substances for pH adjustment, fragrances, solubilizers, fluorescent agents, colorants, foaming Agents, foam stabilizers, polishes, bactericides, bleaching agents, bleaching aids, enzymes, dyes, solvents and the like are suitable. In the case of a powder detergent, it is preferable to blend zeolite. When used in the detergent, the water-soluble polymer is preferably added in an amount of 0.1 to 20% by mass, more preferably 0.2 to 10% by mass, and still more preferably 0.8 to 100% by mass of the detergent. It is 3-5 mass%, Most preferably, it is 0.4-4 mass%. If it is less than 0.1% by mass, the cleaning power of the detergent may be insufficient, and if it exceeds 20% by mass, it may be uneconomical.

  The form of the water-soluble polymer in the detergent may be liquid or solid, and can be determined according to the form at the time of sale of the detergent (for example, liquid or solid). You may mix | blend with the form of the aqueous solution after superposition | polymerization, you may mix | blend in the state which reduced the water | moisture content of the aqueous solution to some extent, and may mix | blend in the state solidified dry. The above detergents are used only for specific applications such as synthetic detergents for household detergents, textile industry and other industrial detergents, hard surface cleaners, bleach detergents that enhance the function of one of its components, and fiber auxiliaries. Also includes the detergent used.

  The surfactant is at least one selected from anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants, and these surfactants include one or more. Can be used. When using 2 or more types, the combined use amount of the anionic surfactant and the nonionic surfactant is preferably 50% by mass or more with respect to 100% by mass of the total surfactant. More preferably, it is 60 mass% or more, More preferably, it is 70 mass% or more, Most preferably, it is 80 mass% or more.

  Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl ether sulfate, alkenyl ether sulfate, alkyl sulfate, alkenyl sulfate, α-olefin sulfonate, α-sulfo fatty acid or ester salt, alkane sulfonic acid. Salt, saturated fatty acid salt, unsaturated fatty acid salt, alkyl ether carboxylate, alkenyl ether carboxylate, amino acid type surfactant, N-acyl amino acid type surfactant, alkyl phosphate ester or salt thereof, alkenyl phosphate ester Or its salt etc. are suitable. The alkyl group or alkenyl group in the anionic surfactant may have a branched alkyl group such as a methyl group.

  Examples of the nonionic surfactant include polyoxyalkylene alkyl ether, polyoxyalkylene alkenyl ether, polyoxyethylene alkyl phenyl ether, higher fatty acid alkanolamide or its alkylene oxide adduct, sucrose fatty acid ester, alkyl glycoxide, fatty acid glycerin. Monoesters, alkylamine oxides and the like are preferred. The alkyl group or alkenyl group in the nonionic surfactant may have a branched alkyl group such as a methyl group. As the cationic surfactant, a quaternary ammonium salt or the like is preferable. As the amphoteric surfactant, a carboxyl type amphoteric surfactant, a sulfobetaine type amphoteric surfactant and the like are suitable. The alkyl group and alkenyl group in the cationic surfactant and amphoteric surfactant may be branched from an alkyl group such as a methyl group.

  In general, the blending ratio of the surfactant is preferably 10 to 60% by mass with respect to 100% by mass of the liquid detergent. More preferably, they are 15 mass% or more and 50 mass% or less, More preferably, they are 20 mass% or more and 45 mass% or less, Especially preferably, they are 25 mass% or more and 40 mass% or less. If the blending ratio of the surfactant is less than 10% by mass, sufficient detergency may not be exhibited, and if it exceeds 60% by mass, the economy may be lowered.

  As the enzyme that can be blended in the detergent of the present invention, amylase, protease, lipase, cellulase and the like are suitable. Of these, alkaline amylase, protease, alkaline lipase, and alkaline cellulase, which are highly active in an alkaline washing solution, are preferred. The amount of the enzyme added is preferably 5% by mass or less with respect to 100% by mass of the detergent. If it exceeds 5% by mass, improvement in detergency cannot be seen, and the economy may be reduced.

  As the alkali builder, silicate, carbonate, sulfate and the like are preferable. As the chelate builder, diglycolic acid, oxycarboxylate, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), citric acid and the like are preferable. A water-soluble polycarboxylic acid polymer may be used. The above-mentioned detergent has excellent dispersibility, and can be a highly stable detergent with extremely high quality agent performance that is unlikely to cause deterioration in performance when stored for a long period of time or precipitation of impurities when held at a low temperature.

  The said water treatment agent is added to water systems, such as a cooling water system and a boiler water system, for example. In this case, the water-soluble polymer may be added as it is, or one containing other components other than the water-soluble polymer may be added. As other composition components and blending ratios other than the water-soluble polymer in the water treatment agent, various effects that can be used in normal water treatment agents and blending ratios thereof are not impaired. It can use suitably in the range.

  The dispersant may be an aqueous dispersant, and for example, a pigment dispersant, a cement dispersant, a calcium carbonate dispersant, a kaolin dispersant, and the like are suitable. The dispersing agent can express extremely excellent dispersibility inherent in the water-soluble polymer. In addition, it is possible to obtain a very high quality, high performance, and highly stable dispersant that does not cause deterioration in performance or precipitation of impurities when kept at a low temperature even when stored for a long period of time.

  As other composition components and blending ratios other than the water-soluble polymer in the dispersant, various components that can be used in ordinary dispersants, and based on the blending ratio, the range does not impair the effects of the present invention. It can be used as appropriate. Thus, the water-soluble polymer of the present invention is suitable for use in detergent builders, detergents, water treatment agents or dispersants, but also in other uses where the water-soluble polymer is used. Various properties exhibited by the copolymer can be improved and used suitably.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, “parts” means “parts by weight” and “%” means “mass%”.

Example 1
A 2 L glass separable flask was provided with a pump for extracting the reaction liquid, and a circulation line capable of adjusting the opening degree, coming out of the flask and circulating outside the flask and returning to the flask. The circulation line was provided with a raw material supply port, a cooler and a static mixer. In addition, a discharge line was branched off from the circulation line. In addition, four paddle stirring blades were installed in the flask. In this way, a loop line type reactor (polymer production apparatus) was produced.

This separable flask was previously charged with 720 g of water and heated to 90 ° C. Under such conditions, the reaction liquid extraction pump was started and the temperature of the cooling water and the amount of cooling water were adjusted so that the temperature in the flask was maintained at 90 ° C., while the 80 wt% aqueous acrylic acid solution was 834.2 g / hr from the raw material supply port. 48 weight% sodium hydroxide aqueous solution 38.6 g / hr, 35 weight% sodium hydrogen sulfite aqueous solution 119.2 g / hr, 15 mass% sodium persulfate (sodium peroxodisulfate) aqueous solution 123.6 g / hr, 14.2 ppm mol An aqueous salt solution of 506.9 g / hr was added. The total mass of the added monomer, initiator, chain transfer agent and catalyst aqueous solution was 1440 g / hr, and the residence time of the reaction solution was 30 minutes. Further, the circulation ratio (= circulation amount / external liquid removal amount) was adjusted to be 10. The required stirring power Pv given by the stirring blade was 2.5 kW / m ³ . After reacting the reaction liquid (circulated liquid) for 3 hours in this state, the supply and circulation of the raw materials were stopped, the reaction liquid remaining in the flask was taken out after cooling, and neutralized until pH 7 was obtained by adding 48 mass% sodium hydroxide. did. After neutralization, the molecular weight was measured by GPC. As a result, the weight average molecular weight Mw was 5,157, and the molecular weight distribution was 2.266.

(Example 2)
A water-soluble polymer was obtained in the same manner as in Example 1 except that a Max Blend (registered trademark) type stirring blade was used instead of the four-paddle stirring blade. The required stirring power Pv given by the stirring blade was 2.5 kW / m ³ . After neutralization, when the molecular weight of the obtained polymer was measured by GPC, the weight average molecular weight Mw was 8,296, and the molecular weight distribution was 2.751.

(Example 3)
A water-soluble polymer was prepared in the same manner as in Example 1 except that a vertical stirring blade (blade length / inner diameter = 0.9, impeller width / inner diameter = 0.1) was used instead of the four-paddle stirring blade. Got. The required stirring power Pv given by the stirring blade was 2.5 kW / m ³ . After neutralization, when the molecular weight of the obtained polymer was measured by GPC, the weight average molecular weight Mw was 7,842, and the molecular weight distribution was 2.628.

(Comparative Example 1: Batch polymerization)
350 g of water and Mole salt were added to a 2 L glass separable flask and heated to 90 ° C. While stirring with a Teflon stirring blade (normal paddle type) under the conditions, the flask was cooled with air so that the temperature in the flask was maintained at 90 ° C. Sodium hydroxide aqueous solution, 35 wt% sodium hydrogensulfite aqueous solution, and 15 mass% sodium persulfate (sodium peroxodisulfate) aqueous solution were added in the prescribed amounts shown in Table 1. The stirring required power Pv given by the stirring blade used in this comparative example was 1.02 kW / m ³ . The rate of addition is as shown in Table 1, and the molecular weight was adjusted by increasing or decreasing sodium bisulfite. The temperature was maintained for 30 minutes after the supply of the raw materials was completed, and then cooled and neutralized until 48 mass% sodium hydroxide was added to reach pH 7.

As described above, a plurality of polymers having different weight average molecular weights and molecular weight distributions were obtained. From the molecular weight and molecular weight distribution obtained in Comparative Example 1, the molecular weight distribution at a predetermined weight molecular weight of the polymer obtained by batch polymerization can be estimated using the following correlation equation (1) between the molecular weight and the molecular weight distribution. .
y = a ln x + b (1)
In the formula (1), y is a molecular weight distribution, x is a weight average molecular weight, and ln is a logarithm (natural logarithm) with the Napier number e as a base. From the formula (1), the estimated molecular weight distribution of the polymer obtained by batch polymerization was calculated at the weight average molecular weight equivalent to the polymers obtained in Examples 1 to 3. The results are shown in Table 2. The molecular weight distribution of the polymer actually obtained by batch polymerization having a weight average molecular weight (Mw: 5,963) close to the weight average molecular weight of the polymer obtained in Example 1 was 2.501. . Furthermore, the molecular weight distribution of the polymer actually obtained by batch polymerization having a weight average molecular weight (Mw: 8,354) close to the weight average molecular weight of the polymer obtained in Example 2 was 2.826. . In addition, the molecular weight distribution of the polymer actually obtained by batch polymerization having a weight average molecular weight (Mw: 7,746) close to the weight average molecular weight of the polymer obtained in Example 3 was 2.728. It was. FIG. 4 shows the relationship between the weight average molecular weight and the molecular weight distribution of the polymers of Examples 1 to 3 and Comparative Examples 1 to 4.

(Comparative Example 2)
In the formulation of Comparative Example 1-7 in Table 1, a water-soluble polymer was obtained in the same manner as Comparative Example 1-7, except that the required power Pv for stirring was changed to 2.5 kW / m ³ . After neutralization, the molecular weight of the obtained polymer was measured by GPC. As a result, the weight average molecular weight Mw was 6,810 and the molecular weight distribution was 2.621.

(Comparative Example 3)
A water-soluble polymer was obtained in the same manner as in Comparative Example 2 except that a Max Blend (registered trademark) type stirring blade was used. After neutralization, the molecular weight of the obtained polymer was measured by GPC. As a result, the weight average molecular weight Mw was 6,392 and the molecular weight distribution was 2.598.

(Comparative Example 4)
A water-soluble polymer was obtained in the same manner as in Comparative Example 2 except that the anchor blade was used. When the molecular weight of the obtained polymer was measured by GPC after neutralization, the weight average molecular weight Mw was 6,107 and the molecular weight distribution was 2.555.

  As is clear when Examples 1 to 3 and Comparative Examples 1 to 4 are compared, the effect of narrowing the molecular weight distribution by using a combination of a loop line reactor (polymer production device) and a specific stirring blade. It became clear that is played.

  According to the present invention, a water-soluble polymer having a very narrow molecular weight distribution can be obtained with very high productivity. The water-soluble polymer obtained by the present invention includes an aqueous dispersant (including a pigment dispersant), a scale inhibitor (scale inhibitor), a detergent builder, and a detergent, a metal ion sealing agent, and a thickener. It can be suitably used for various binders.

It is a conceptual diagram explaining the water-soluble polymer manufacturing apparatus by one Embodiment of this invention. It is a conceptual diagram explaining the water-soluble polymer manufacturing apparatus by another embodiment of this invention. It is a conceptual diagram which shows the area ratio obtained by gel permeation chromatography (GPC). It is a graph which shows the relationship between the weight average molecular weight and molecular weight distribution of the polymer of Examples 1-3 and Comparative Examples 1-4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Water-soluble polymer manufacturing apparatus 1 Tank 2 Circulation line 3 Discharge line 4 Cooler 5 Mixing device 6 Circulation pump 7 Alkaline agent supply port 8 Monomer supply port 9 Chain transfer agent supply port 10 Polymerization initiator supply port 11 Agent supply Port 12 Stirring means a Tank outlet b Tank return port

Claims (8)

A tank for temporarily storing a circulating fluid containing a monomer containing an unsaturated carboxylic acid monomer ;
A circulation line that circulates out of the tank, circulates outside the tank, returns to the tank, and circulates the circulating liquid;
A discharge line for discharging a part of the circulating fluid,
The circulation line has at least one cooler , at least one monomer supply port, at least one mixing device, and at least one polymerization initiator supply port.
The cooler, the monomer supply port, the mixing device, and the polymerization initiator supply port are arranged along the flow direction of the circulating liquid in the circulation line by the cooler / monomer supply port / mixing device / polymerization. Arranged in the order of the initiator supply port or in the order of cooler / monomer supply port / polymerization initiator supply port / mixing device,
An apparatus for producing a water-soluble polymer, wherein the tank is provided with stirring means using a stirring blade selected from the group consisting of a paddle stirring blade, a saddle stirring blade, a lattice stirring blade, and a large flat blade.   The water-soluble polymer production apparatus according to claim 1, wherein the discharge line is provided separately from the circulation line. The water-soluble polymer manufacturing apparatus of Claim 1 or 2 whose said mixing apparatus is a motionless mixer. The water-soluble polymer manufacturing apparatus in any one of Claim 1 to 3 whose polymerization initiator supplied from the said polymerization initiator supply port is a persulfate and / or hydrogen peroxide. The circulation line further has a chain transfer agent supply port, and the chain transfer agent supplied from the chain transfer agent supply port includes sulfurous acid (salt), hydrogen sulfite (salt), pyrosulfite (salt), phosphorous acid ( Salt), hypophosphorous acid (salt), mercapto group-containing compound, mercaptan compound, and secondary alcohol, the water-soluble polymer production apparatus according to any one of claims 1 to 4. A circulating liquid containing a monomer containing an unsaturated carboxylic acid monomer is polymerized while being circulated through a circulation line that exits the tank, circulates outside the tank, and returns to the tank. A continuous production method of a conductive polymer,
Cooling the circulating fluid at at least one location of the circulating line;
Mixing the circulating fluid in at least one location of the circulation line;
Discharging a part of the circulating fluid out of the circulation line;
A step of stirring the circulating liquid in the tank,
In the circulation line, the monomer is supplied after the cooling step and before the mixing step, and the polymerization initiator is supplied after the mixing step, or the monomer and the polymerization initiator are supplied after the cooling step and before the mixing step. Including
The continuous production method of a water-soluble polymer, wherein the stirring is performed using a stirring blade selected from the group consisting of a paddle stirring blade, a saddle stirring blade, a lattice stirring blade, and a large flat blade. The method for continuously producing a water-soluble polymer according to claim 6, wherein the polymerization initiator is a persulfate and / or hydrogen peroxide. And supplying a chain transfer agent in the circulation line, wherein the chain transfer agent comprises sulfurous acid (salt), hydrogen sulfite (salt), pyrosulfite (salt), phosphorous acid (salt), hypophosphorous acid ( Salt), a mercapto group-containing compound, a mercaptan compound, and a secondary alcohol, The method for continuously producing a water-soluble polymer according to claim 6 or 7.

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