JP2010150327A - Method for producing carboxylic acid-based polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably and efficiently produce a polymer having high purity, whose molecular weight and distribution thereof are suitable for a detergent builder, a dispersant, a scale preventive and the like. <P>SOLUTION: The method for producing a carboxylic acid-based polymer employs a reactor 10 including a reaction tank 11, an external circulating line 12, a monomer feeding means 19, and polymerization initiator feeding means 14, 15. While a reaction solution in the reaction tank 11 is circulated through the external circulating line 12, a monomer is continuously fed from the monomer feeding means 19 to the reaction solution, and a redox initiator is also continuously fed from the polymerization initiator feeding means 14, 15, then the monomer is redox-polymerized to produce a carboxylic acid-based polymer through a semibatch operation. The reaction solution is circulated through the external circulating line 12 at least 17 times during the monomer feeding period. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a carboxylic acid polymer by semi-batch operation. More specifically, the present invention relates to a method for producing a carboxylic acid polymer that can be suitably used as a detergent builder, a dispersant, a scale inhibitor, etc., in a semi-batch operation.

  As a method for producing a carboxylic acid polymer that is polymerized in the presence of a bisulfite and oxygen redox initiator, a method in which a polymerization reaction is carried out by a dropping method in a stirred tank reactor (see, for example, Patent Document 1) and reaction A method of performing a polymerization reaction by forming a thin film flow in a tube (for example, see Patent Document 2) is known.

  As a polymerization method other than the above, a method is known in which a monomer and a redox initiator are continuously mixed with a static mixer and then supplied to an appropriate polymerization vessel (for example, see Patent Document 3).

Moreover, as a method of continuously producing an acrylate polymer, a method of producing using a loop reactor equipped with a static mixer (for example, see Patent Document 4), a flow mixer was provided. A method of producing by a first polymerization step and a second polymerization reaction step (see, for example, Patent Document 5) and a method of producing by a loop reactor having a static mixer and a recycling tank (for example, see Patent Document 6) It has been known.
Japanese Patent Publication No. 60-24806 Japanese Patent Publication No. 02-24283 Japanese Patent Publication No. 60-8001 JP 60-28409 A Japanese Patent No. 3730615 JP 2001-98001 A

  However, in the method described in Patent Document 1, since it is difficult to control the bubble diameter when the scale is increased, it is necessary to reduce the solid content concentration, and when the low molecular weight polymer is obtained, the process is started. The dose should be increased. Therefore, this method has the disadvantages that productivity is reduced and the generation rate of impurities is increased.

  The method described in Patent Document 2 has a drawback that an enormous amount of gas is required to form a thin film flow in the reaction tube.

  In the method described in Patent Document 3, the redox initiator needs to be liquid at the stage of introduction into the mixer, the initiation reaction rate is high, and the mixer specifications and initiator supply method are used to prevent clogging. There is a disadvantage that there is a restriction.

  In the method described in Patent Document 4, productivity is low, and when a gas-liquid system is handled, the gas separation mechanism is insufficient, and thus there is a disadvantage that circulation cannot be performed.

  The method described in Patent Document 5 has the disadvantages that the productivity is high but the construction equipment construction cost is high, and that the maintenance of the equipment takes time and money.

  In the method described in Patent Document 6, when bisulfite and oxygen are used as a redox initiator, these initiator and monomer are directly fed into the loop, and a polymer having a high water-soluble viscosity circulates. The starting reaction will be performed in the state. As a result, a polymerization reaction with high initiator efficiency cannot be performed, and the amount of impurities increases. Therefore, when the initiator is increased to reduce the viscosity of the water-soluble polymer in order to increase the initiator efficiency and the molecular weight is decreased, the amount of impurities derived from the initiator also increases, and the water-soluble polymer When the concentration is lowered, there is a disadvantage that productivity is lowered.

  The present invention relates to a method for producing a carboxylic acid polymer using bisulfite and oxygen as a redox initiator in a semi-batch operation, and has high purity, and the molecular weight and distribution thereof are a builder for detergent, a dispersant, a scale. It is an object of the present invention to produce a carboxylic acid polymer suitable for an inhibitor and the like stably and with high productivity.

The present invention supplies a reaction vessel, an external circulation line having both ends connected to the reaction vessel, a monomer supply means for supplying a monomer containing an α-unsaturated carboxylic acid and / or a salt thereof, and a redox initiator. A polymerization initiator supply means, and continuously supplying the monomer from the monomer supply means to the reaction liquid while circulating the reaction liquid in the reaction tank to the external circulation line. , By continuously supplying a redox initiator from the polymerization initiator supply means, the monomer is redox polymerized to produce a carboxylic acid polymer by semi-batch operation,
The reaction solution is circulated 17 times or more in the external circulation line during the monomer supply time.

The present invention also includes a reaction tank for storing a reaction solution,
An external circulation line having both ends connected to the reaction vessel;
Liquid feeding means for circulating the reaction liquid in the reaction tank interposed in the external circulation line to the external circulation line;
Monomer supply means for supplying a monomer containing an α-unsaturated carboxylic acid and / or a salt thereof to the reaction solution;
A polymerization initiator supply means for supplying a redox initiator to the reaction solution;
And a reactor configured to redox polymerize the monomer and produce a carboxylic acid polymer by semi-batch operation.

  According to the present invention, a carboxylic acid polymer having high purity and having a molecular weight and distribution suitable for detergent builders, dispersants, scale inhibitors and the like can be produced stably and with high productivity.

  Hereinafter, embodiments will be described in detail.

(Reactor)
FIG. 1 shows a reaction apparatus 10 according to this embodiment. In addition, although this embodiment illustrates the case where the redox initiator which consists of hydrogen sulfite and the gas containing oxygen is illustrated, it is not specifically limited to this.

  The reaction apparatus 10 according to the present embodiment includes a reaction tank 11 having a capacity of, for example, 10 to 30000 L having a stirring function and a temperature control function, and the reaction liquid is stored in the reaction tank 11.

  The reaction tank 11 is provided with an external circulation line 12 having one end connected to the lower part of the tank and the other end connected to the upper part of the tank. The external circulation line 12 has, for example, a channel length of 1 to 50 m and a channel diameter of 20 to 500 mm.

  The external circulation line 12 is provided with a circulation pump 13 (liquid feeding means). The circulation pump 13 feeds the reaction liquid in the reaction tank 11 from the lower part of the tank toward the upper part of the tank. Circulate to the external circulation line 12.

  In the external circulation line 12, an oxygen-containing gas extending from a bisulfite supply pipe 14 extending from a bisulfite supply source and an oxygen-containing gas supply source (for example, a compressor or a blower facility) downstream of the circulation pump 13. Supply pipes 15 are connected to each other. The bisulfite supply pipe 14 supplies an aqueous solution (hereinafter referred to as “bisulfite aqueous solution”) in which bisulfite is dissolved to the reaction liquid, and the oxygen-containing gas supply pipe 15 supplies oxygen to the reaction liquid. By supplying the contained gas (hereinafter referred to as “oxygen-containing gas”), a redox initiator composed of bisulfite and oxygen is supplied to the reaction solution. Therefore, these bisulfite supply pipe 14 and oxygen-containing gas supply pipe 15 constitute a polymerization initiator supply means. The bisulfite supply pipe 14 and the oxygen-containing gas supply pipe 15 are not connected to the external circulation line 12, but the bisulfite supply pipe 14 and the oxygen-containing gas supply pipe 15 are connected to join them. The structure in which the pipe | tube was connected to the external circulation line 12 may be sufficient.

  A circulation mixer 16 is interposed in the external circulation line 12 so that the connecting portion of the bisulfite supply pipe 14 and the oxygen-containing gas supply pipe 15 is arranged on the upstream side. The flow mixer 16 performs gas-liquid mixing of the reaction liquid flowing through the external circulation line 12 and the oxygen-containing gas. As described above, the connection part of the oxygen-containing gas supply pipe 15 is arranged on the upstream side of the flow mixer 16, thereby improving the dispersibility of the gas and liquid and the solubility of oxygen in the circulating reaction liquid. Can do.

  Examples of the flow mixer 16 include a static mixer such as a static mixer or an orifice mixer; a jet nozzle such as an ejector; a pipe stirrer such as a line mixer. Among these, a static mixer is preferable from the viewpoints of exhibiting high mixing performance even with a small amount of gas, as well as durability of equipment, maintenance, and the like. As the static mixer, for example, “Dispersion-kun” (manufactured by Fujikin Co., Ltd.) can be preferably used.

  In the external circulation line 12, a heat exchanger 17 is provided on the downstream side of the flow mixer 16. The heat exchanger 17 regulates the temperature of the gas-liquid mixed fluid that flows through a portion of the external circulation line 12 downstream of the flow mixer 16.

  A control valve 18 is provided on the external circulation line 12 on the downstream side of the flow mixer 16. The control valve 18 adjusts the flow rate of the gas-liquid mixed fluid flowing through the portion of the external circulation line 12 downstream of the flow-type mixer 16, thereby setting the pressure of the circulation line return portion applied to the gas-liquid mixed fluid. .

  A monomer supply pipe 19 extending from the monomer supply source is connected to the reaction tank 11 at the top of the tank. The monomer supply pipe 19 supplies monomer to the reaction solution in the reaction tank 11. Therefore, the monomer supply pipe 19 constitutes a monomer supply means. Note that the monomer supply pipe 19 may be connected to the external circulation line 12 instead of being connected to the reaction tank 11.

  Moreover, you may install in the reaction tank 11 and the external circulation line 12 the neutralizing agent supply line for neutralizing a monomer.

(Method for producing polymer)
The method for producing a carboxylic acid-based polymer (hereinafter referred to as “polymer”) according to the present embodiment uses the reaction apparatus 10 to react while circulating the reaction liquid in the reaction tank 11 to the external circulation line 12. The monomer is continuously supplied from the monomer supply pipe 19 to the liquid, and the redox initiator composed of hydrogen sulfite and oxygen is continuously supplied from the hydrogen sulfite supply pipe 14 and the oxygen-containing gas supply pipe 15 to thereby provide the monomer. Is polymerized by a half-batch operation. Then, the reaction solution is circulated 17 times or more in the external circulation line 12 during the monomer supply time.

  By doing so, a polymer having high purity and having a molecular weight and distribution suitable for detergent builders, dispersants, scale inhibitors and the like can be produced stably and with high productivity.

<Monomer>
The α-unsaturated carboxylic acid or a salt thereof is used as a monomer for the reaction raw material. Among the α-unsaturated carboxylic acids or salts thereof, a monomer containing acrylic acid or a salt thereof as an essential component is preferable because it is suitable for homopolymerization or copolymerization. Acrylic acid can be used as an acrylic acid aqueous solution containing 60% by mass or more of acrylic acid anhydride or acrylic acid. The aqueous acrylic acid solution may be an aqueous solution of an alkali metal acrylate that is partially or wholly neutralized, such as an aqueous sodium acrylate solution or an aqueous potassium acrylate solution.

  The monomer may contain a hydrophilic monomer copolymerizable with an α-unsaturated carboxylic acid or a salt thereof, such as maleic acid, acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and the like. . The content of the hydrophilic monomer in the monomer is preferably 0 to 30 mol% from the viewpoint of increasing the polymerization reaction rate and facilitating the control of the molecular weight.

  When the monomer is supplied as an aqueous solution, the temperature of the aqueous monomer solution is preferably 5 ° C. or higher from the viewpoint of handling as an aqueous solution, and 30 ° C. or lower from the viewpoint of suppressing polymerization of the monomer before starting the reaction. From these viewpoints, the temperature of the aqueous monomer solution is preferably 5 to 30 ° C. When maleic acid is copolymerized, when maleate is used as an aqueous solution, the temperature of the maleate aqueous solution is preferably 50 to 90 ° C.

<Redox initiator>
As the redox initiator, those composed of bisulfite and oxygen are preferably used.

  Examples of the bisulfite include sodium bisulfite, potassium bisulfite, magnesium bisulfite and the like. Among these, sodium bisulfite having a strong reducing action is preferable.

  Bisulfite is supplied to the reaction solution as a bisulfite aqueous solution, and the concentration thereof is preferably 1 to 40% by mass, more preferably 20 to 40% by mass, from the viewpoint of productivity.

  The supply amount of bisulfite facilitates control of the molecular weight suitable for the intended use, and is an addition reaction substance (hereinafter referred to as “adduct”) of bisulfite and α-unsaturated carboxylic acid or a salt thereof. ) Is preferably 0.008 to 0.1 mol with respect to 1 mol of the monomer.

  Oxygen is supplied as an oxygen-containing gas to the reaction solution, but air is generally used, and pure oxygen or a gas obtained by diluting pure oxygen with an inert gas may be used. The oxygen concentration in the oxygen-containing gas is preferably 10% by volume or more, more preferably 20% by volume or more, from the viewpoint of reactivity with bisulfite. From the viewpoint of stabilizing the reaction, it is preferable to supply the oxygen-containing gas at a constant pressure and a constant volume.

  The ratio of the oxygen-containing gas flow rate to the reaction solution flow rate per unit time in the gas-liquid mixed fluid introduced into the flow mixer 16 (the volume of the oxygen-containing gas standard state (273K, 101.3 kPa) is the volume of the reaction solution) The value obtained by dividing (hereinafter referred to as “liquid-gas ratio”) is 0.1 or more, more preferably 0.5 from the viewpoint of increasing the solubility of the oxygen-containing gas in the reaction liquid and performing a polymerization reaction with high initiator efficiency. From the viewpoint of reducing the pressure loss in the mixing section and reducing the load of an oxygen-containing gas supply source such as a compressor that supplies the oxygen-containing gas, it is preferably 50 or less, more preferably 20 or less. From these viewpoints, the liquid gas ratio is preferably 0.1 to 50, more preferably 0.5 to 20.

<Monomer supply time>
The monomer supply time is preferably 0.5 hours or more, more preferably 1 hour or more, from the viewpoint of heat generation control by reaction. Moreover, from a viewpoint of productivity, 50 hours or less are preferable and 30 hours or less are more preferable.

<Aging time>
The aging time is not particularly limited, and may be set so that the residual monomer in the reaction solution becomes a predetermined value or less. For example, it is 1 to 10 hours.

<Number of reaction liquid circulation in external circulation line>
The number of times the reaction liquid is circulated in the external circulation line 12 refers to the number of times that the reaction liquid is circulated to the external circulation line 12 during the monomer supply time. Specifically, it can be determined by the following.

When the flow rate of the reaction liquid circulated per unit time is Q [L / h], and the total amount of the reaction liquid (average value during the monomer supply time because it increases with the supply of raw materials over time) is V [L], the unit The average number of circulations per hour N [times / h] is
N [times / h] = Q [L / h] / V [L]
It becomes.

Further, when this N is multiplied by the monomer supply time T [h], the average number of circulations [times] during the monomer supply time can be obtained. That is,
Average number of circulations during monomer supply time [times] = N [times / h] × T [h]
It is.

  From the viewpoint of improving the contact between the monomer and the redox initiator, the average number of circulation during the monomer supply time is preferably 17 times or more, and more preferably 18 times or more. Also, from the viewpoint of reducing the load on the circulation pump 13, it is preferably 100 times or less, and more preferably 80 times or less.

<Reaction temperature>
The reaction temperature is preferably 80 ° C. or lower, more preferably 60 ° C. or lower, from the viewpoint of suppressing the molecular chain branching and hue deterioration of the polymer and suppressing the formation of adducts. From the viewpoint of handling as a polymer aqueous solution, it is preferably 5 ° C or higher, more preferably 10 ° C or higher. From these viewpoints, the reaction temperature is preferably 5 to 80 ° C, more preferably 10 to 60 ° C.

<Circulation line return pressure>
When the reaction solution is circulated in the external circulation line 12 in the polymerization reaction, the circulation line return portion pressure (gauge pressure) is set to 0.05 MPa or more from the viewpoint of enhancing the solubility of oxygen in the oxygen-containing gas in the circulated reaction solution. It is preferable to pressurize at a pressure of 0.1 MPa or more. From the viewpoint of reducing the load on the circulation pump 13, the circulation line return portion pressure is preferably 1 MPa or less, and more preferably 0.5 MPa or less. The pressure of the circulation line return portion pressure can be set by adjusting the control valve 18.

<Raw material supply method>
The reaction raw material of the monomer and / or redox initiator may be supplied to the reaction solution at a constant supply rate. In the semi-batch polymerization, the reaction solution is thickened in the later stage of the reaction, and the reaction solution of oxygen in the gas Since the dissolution rate in water may decrease and the monomer concentration in the reaction solution may increase, the supply rate may be changed during the process. When changing the supply rate of the reaction raw material in the middle, a method of gradually decreasing the supply rate from the initial stage of the reaction is preferable.

<Polymer>
From the viewpoint of improving quality, it is preferable to continue the reaction until the polymerization rate in the polymerization reaction step reaches 98% or more, and from the viewpoint of further increasing the polymerization rate, an aging operation for reducing unreacted monomers is performed. Is more preferable.

  The content of the unreacted monomer in the polymer is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, based on the polymer solid content, from the viewpoint of improving the quality and yield. is there.

  The content of the adduct is preferably 4.0% by mass or less with respect to the polymer solid content from the viewpoint of improving the quality and yield.

  The weight average molecular weight (Mw) of the polymer is usually preferably from 1,000 to 100,000 from the viewpoint of enhancing dispersibility and adsorptivity, and when the polymer is used for a builder for detergent, a dispersant, a scale inhibitor or the like. The weight average molecular weight (Mw) is preferably 2000 to 30000. Further, the value (Mw / Mn, hereinafter referred to as “dispersion index”) obtained by dividing the weight average molecular weight (Mw) as an index of the molecular weight distribution by the number average molecular weight (Mn) is preferably 7 or less, more preferably 5 It is as follows.

  The physical properties of the polymers obtained in Examples and Comparative Examples were measured by the following methods.

(1) Measurement of unreacted monomer amount and adduct amount and calculation of polymerization rate The unreacted monomer amount and adduct amount are measured by HPLC (high performance liquid chromatography) and the unreacted monomer amount and adduct amount at a known concentration are measured. The concentration in the polymer aqueous solution was calculated from the calibration curve.

  Further, the polymerization rate was calculated based on the following formula from the amount of unreacted monomer before and after the reaction and the amount of monomer converted to an adduct.

The standard adduct (3-sulfopropionic acid disodium salt) was synthesized in the same manner as Schenck, RTE and Danishefski, I., J. Org. Chem., 16, 1683 (1951) The amount of the unreacted monomer was measured by 1 and the amount of the polymer was measured by ¹ H-NMR (proton nuclear magnetic resonance method) to determine the purity of the standard adduct.

The HPLC measurement conditions are shown below.
・ Column: Tosoh Corporation, trade name: TSK-GEL ODS-80TS
-Mobile phase: 0.02 mol / L aqueous solution prepared by adding phosphoric acid to potassium dihydrogen phosphate to adjust pH to 2.5-Detector: UV detector (wavelength: 210 nm)
-Column temperature: 30 ° C
・ Flow rate: 1.0 mL / min
Sample: Ion exchange water is added to a polymer aqueous solution containing a solid content of 0.8 g to prepare a total liquid volume of 200 mL, and 10 μL is taken from this prepared liquid and injected into a column.

(2) Measurement of molecular weight and calculation of dispersion index The molecular weight was measured by GPC (gel permeation chromatography), and the weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined from the converted standard substance. The dispersion index was calculated based on the following formula from the weight average molecular weight (Mw) and the number average molecular weight (Mn).

The GPC measurement conditions are shown below.
・ Column: Tosoh Corporation, trade name: TSK-GEL guard PWXL
Product name: TSK-GEL G4000 PWXL, manufactured by Tosoh Corporation
Product name: TSK-GEL G2500 PWXL, manufactured by Tosoh Corporation
Mobile phase: 0.1 mol / L potassium dihydrogen phosphate and 0.1 mol / L sodium dihydrogen phosphate in water / acetonitrile = 90/10 (volume ratio)
-Detector: Differential refractive index detector-Column temperature: 40 ° C
・ Flow rate: 1.0 mL / min
・ Conversion standard material: Polyacrylic acid [American Standard Corporation (manufactured by AMERICAN STANDARD CORP)]
Sample: Ion exchange water is added to a polymer aqueous solution containing a solid content of 0.8 g to prepare a total liquid volume of 200 mL, and 10 μL is taken from this prepared liquid and injected into a column.

<Example 1>
A reaction apparatus having the same configuration as that shown in FIG. 1 and equipped with a 300 L SUS304 reaction vessel with an external circulation line was used. In the external circulation line, in the order of the liquid flow, a circulation pump, a static mixer (manufactured by Fujikin Co., Ltd., trade name: Dispersion Kim 15D type, flow path constriction part flow path inner diameter 3 mm, 2 units) and A heat exchanger was attached. The reaction tank was accompanied by an inclined paddle stirring blade.

  The reaction tank was initially charged with 106 kg of ion exchange water. The stirring rotation speed of the inclined paddle stirring blade of the reaction tank was set to 135 rpm, the circulating reaction liquid flow rate Q was set to 400 L / h, and the liquid temperature in the tank was adjusted to 35 ° C.

  Acrylic acid having a concentration of 98% by mass was supplied to the reaction vessel at a constant rate of 6.0 kg / h and caustic soda having a concentration of 48% by mass at 6.6 kg / h. At the same time, 35 mass% sodium hydrogen sulfite aqueous solution was supplied to the external circulation line at 1.45 kg / h, and air was supplied as an oxygen-containing gas at a constant rate of 2,200 N-L / h, and the monomer supply time T was set to 14 h for polymerization. Reaction was performed. The liquid gas ratio was 5.5. The gas-liquid mixed fluid was not pressurized with the circulation line return section pressure. During this time, the liquid temperature in the tank was controlled at 35 ° C.

  Subsequently, a ripening reaction was carried out at the same temperature of 35 ° C. for 2 hours to complete the polymerization reaction. Since the total amount V (average value during the monomer supply time) of the reaction liquid was 167 L, the average circulation number N was 2.4 times / h. Therefore, the average circulation number of the reaction liquid during the monomer supply time was Was 34 times.

  As a result of analyzing the polymer, as shown in Table 1, the residual monomer in the polymer was 1,435 mg / kg, the adduct in the polymer was 36,075 mg / kg, the polymerization rate was 99.5%, the polymer The weight average molecular weight (Mw) of the polymer was 13,300, and the dispersion index (Mw / Mn) of the polymer was 3.7.

<Example 2>
Using the same reactor as in Example 1, 109 kg of ion-exchanged water was initially charged in the reaction tank. The stirring rotation speed of the inclined paddle stirring blade of the reaction tank was set to 135 rpm, the circulating reaction liquid flow rate Q was set to 400 L / h, and the liquid temperature in the tank was adjusted to 35 ° C.

  Acrylic acid having a concentration of 98% by mass and 6.1% caustic soda at a concentration of 48% by mass were respectively supplied to the reaction tank at a constant rate. At the same time, 35 mass% sodium hydrogen sulfite aqueous solution was supplied to the external circulation line at 1.24 kg / h and air was supplied as oxygen-containing gas at a constant rate of 800 N-L / h. went. The liquid gas ratio was 2.0. The gas-liquid mixed fluid was not pressurized with the circulation line return section pressure. During this time, the temperature of the liquid in the tank was controlled at 35 ° C.

  Subsequently, a ripening reaction was carried out at the same temperature of 35 ° C. for 2 hours to complete the polymerization reaction. Since the total liquid volume V (average value during the monomer supply time) of the reaction liquid was 168 L, the average circulation number N was 2.4 times / h. Therefore, the average circulation number of the reaction liquid during the monomer supply time Was 34 times.

  As a result of analyzing the polymer, as shown in Table 1, the residual monomer in the polymer was 1,386 mg / kg, the adduct in the polymer was 24,475 mg / kg, the polymerization rate was 99.5%, the polymer The weight average molecular weight (Mw) of the polymer was 12,890, and the polymer dispersion index (Mw / Mn) was 3.7.

<Example 3>
Using the same reactor as in Example 1, 106 kg of ion-exchanged water was initially charged in the reaction tank. The stirring rotation speed of the inclined paddle stirring blade of the reaction tank was set to 135 rpm, the circulating reaction liquid flow rate Q was set to 400 L / h, and the liquid temperature in the tank was adjusted to 35 ° C.

  Acrylic acid having a concentration of 98% by mass was supplied to the reaction vessel at a constant rate of 6.0 kg / h and caustic soda having a concentration of 48% by mass at 6.6 kg / h. At the same time, 35 mass% sodium bisulfite aqueous solution was supplied to the external circulation line at 1.45 kg / h, and air was supplied as oxygen-containing gas at a constant rate of 800 N-L / h, respectively, and the monomer supply time T was set to 14 h. went. The liquid gas ratio was 2.0. By adjusting the flow rate, pressurization was performed on the gas-liquid mixed fluid having a circulation line return portion pressure of 0.2 MPa (gauge pressure). During this time, the liquid temperature in the tank was controlled at 35 ° C.

  Subsequently, a ripening reaction was carried out at the same temperature of 35 ° C. for 2 hours to complete the polymerization reaction. Since the total amount of the reaction solution (average value during the monomer supply time) V was 167 L, the average circulation number N was 2.4 times / h. Therefore, the average circulation number of the reaction solution during the monomer supply time was Was 34 times.

  As a result of analyzing the polymer, as shown in Table 1, the residual monomer in the polymer was 962 mg / kg, the adduct in the polymer was 30,427 mg / kg, the polymerization rate was 99.6%, the weight of the polymer The average molecular weight (Mw) was 10,710, and the polymer dispersion index (Mw / Mn) was 3.4.

<Example 4>
Using the same reaction apparatus as in Example 1, 97 kg of ion-exchanged water was initially charged in the reaction tank. The stirring rotation speed of the inclined paddle stirring blade of the reaction tank was set to 135 rpm, the circulating reaction liquid flow rate Q was set to 400 L / h, and the liquid temperature in the tank was adjusted to 35 ° C.

  Supply of acrylic acid with a concentration of 98% by mass to the reaction tank at 11.9 kg / h and caustic soda with a concentration of 48% by mass was started at 13.1 kg / h. At the same time, supply of 35% by mass sodium hydrogen sulfite aqueous solution to the external circulation line at 2.89 kg / h and air as oxygen-containing gas at 2200 N-L / h were started. After 1.4 hours, the raw material supply rate was reduced to the conditions shown in Table 2, and thereafter, the raw material supply rate was reduced stepwise as shown in Table 2 to carry out the polymerization reaction with the monomer supply time T being 8 hours. . The liquid gas ratio of the monomer supply time T average was 5.5. The gas-liquid mixed fluid was not pressurized with the circulation line return section pressure. During this time, the liquid temperature in the tank was controlled at 35 ° C.

  Subsequently, a ripening reaction was carried out at the same temperature of 35 ° C. for 4 hours to complete the polymerization reaction. Since the total liquid volume V (average value during the monomer supply time) of the reaction liquid was 159 L, the average circulation number N was 2.5 times / h. Therefore, the average circulation time of the reaction liquid during the monomer supply time Was 20 times.

  As a result of analyzing the polymer, as shown in Table 1, the residual monomer in the polymer was 985 mg / kg, the adduct in the polymer was 38,008 mg / kg, the polymerization rate was 99.6%, the weight of the polymer The average molecular weight (Mw) was 14,323, and the dispersion index (Mw / Mn) of the polymer was 3.9.

<Comparative Example 1>
Using the same reaction apparatus as in Example 1, 55 kg of ion-exchanged water was initially charged in the reaction tank. The stirring rotation speed of the inclined paddle stirring blade of the reaction tank was set to 135 rpm, the circulating reaction liquid flow rate Q was set to 550 L / h, and the liquid temperature in the tank was adjusted to 35 ° C.

  Acrylic acid having a concentration of 98% by mass was supplied to the reaction tank at a constant rate of 18.5 kg / h and caustic soda having a concentration of 48% by mass at 20.3 kg / h. At the same time, a 35 mass% sodium hydrogen sulfite aqueous solution was supplied to the external circulation line at 4.49 kg / h, and air as an oxygen-containing gas was supplied at a constant rate of 1200 N-L / h. went. The liquid gas ratio was 2.2. The gas-liquid mixed fluid was not pressurized with the circulation line return section pressure. During this time, the temperature of the liquid in the tank was controlled at 35 ° C.

  Subsequently, an aging reaction for 0.5 h was performed at the same temperature of 35 ° C. to complete the polymerization reaction. Since the total liquid volume V (average value during the monomer supply time) of the reaction liquid was 105 L, the average circulation number N was 5.2 times / h. Therefore, the average circulation number of the reaction liquid during the monomer supply time Was 16 times.

  As a result of analyzing the polymer, as shown in Table 1, the residual monomer in the polymer was 7,980 mg / kg, the adduct in the polymer was 43,828 mg / kg, the polymerization rate was 97.3%, the polymer The weight average molecular weight (Mw) of the polymer was 41,190, and the dispersion index (Mw / Mn) of the polymer was 9.7.

<Comparative example 2>
Using the same reaction apparatus as in Example 1, 88 kg of ion-exchanged water was initially charged in the reaction tank. The stirring rotation speed of the inclined paddle stirring blade of the reaction tank was 135 rpm, the circulating reaction liquid flow rate Q was 250 L / h, and the liquid temperature in the tank was adjusted to 35 ° C.

  Acrylic acid having a concentration of 98% by mass was fed to the reaction tank at a constant rate of 8.9 kg / h and caustic soda having a concentration of 48% by mass at 9.8 kg / h, respectively. At the same time, a 35 mass% sodium hydrogen sulfite aqueous solution was supplied to the external circulation line at 2.15 kg / h, and air was supplied as an oxygen-containing gas at a constant rate of 1320 N-L / h. went. The liquid gas ratio was 5.3. The gas-liquid mixed fluid was not pressurized with the circulation line return section pressure. During this time, the liquid temperature in the tank was controlled at 35 ° C.

  Subsequently, an aging reaction was performed for 1 h at the same temperature of 35 ° C. to complete the polymerization reaction. Since the total liquid volume V (average value during the monomer supply time) of the reaction liquid was 164 L, the average circulation number N was 1.5 times / h. Therefore, the average circulation number of the reaction liquid during the monomer supply time Was 14 times.

  As a result of analyzing the polymer, as shown in Table 1, the residual monomer in the polymer was 2,913 mg / kg, the adduct in the polymer was 41,675 mg / kg, the polymerization rate was 99.0%, the polymer The weight average molecular weight (Mw) was 40,650, and the dispersion index (Mw / Mn) of the polymer was 6.8.

  INDUSTRIAL APPLICATION This invention is useful about the manufacturing method by the semibatch operation of the polymer which can be used conveniently as a builder for detergents, a dispersing agent, a scale inhibitor, etc.

It is a figure which shows the reaction apparatus which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reactor 11 Reaction tank 12 External circulation line 13 Circulation pump 14 Bisulfite supply pipe 15 Oxygen-containing gas supply pipe 16 Flow mixer 17 Heat exchanger 18 Control valve 19 Monomer supply pipe

Claims (9)

A reaction tank, an external circulation line having both ends connected to the reaction tank, a monomer supply means for supplying a monomer containing an α-unsaturated carboxylic acid and / or a salt thereof, and a polymerization initiator supply for supplying a redox initiator And continuously supplying the monomer from the monomer supply means to the reaction liquid while circulating the reaction liquid in the reaction tank to the external circulation line and starting the polymerization. A method for producing a carboxylic acid polymer by semi-batch operation by redox polymerization of a monomer by continuously supplying a redox initiator from an agent supply means,
A method for producing a carboxylic acid polymer, wherein the reaction solution is circulated 17 times or more in the external circulation line during a monomer supply time.   The method for producing a carboxylic acid polymer according to claim 1, wherein the redox initiator comprises bisulfite and oxygen.   The method for producing a carboxylic acid polymer according to claim 1 or 2, wherein a flow mixer is interposed in the external circulation line.   The polymerization initiator supply means is connected to a portion upstream of the flow mixer in the external circulation line, and supplies a bisulfite supply pipe for supplying a bisulfite aqueous solution to the reaction liquid and a reaction. The method for producing a carboxylic acid-based polymer according to claim 3, comprising an oxygen-containing gas supply pipe for supplying a gas containing oxygen to the liquid.   The carboxylic acid according to claim 4, wherein a liquid gas ratio, which is a ratio of an oxygen-containing gas flow rate to a reaction liquid flow rate per unit time in a gas-liquid mixed fluid introduced into the flow mixer, is 0.1 to 50. A method for producing a polymer.   The carboxylic acid polymer according to any one of claims 3 to 5, wherein a reaction liquid flowing through a portion downstream from the flow mixer in the external circulation line is pressurized to 0.05 MPa or more by a gauge pressure. Production method.   The method for producing a carboxylic acid polymer according to any one of claims 1 to 6, wherein the monomer supply time is 0.5 to 50 hours.   The carboxylic acid system according to any one of claims 1 to 7, wherein the monomer supply rate to the reaction liquid from the monomer supply means and / or the redox initiator supply speed from the polymerization initiator supply means to the reaction liquid is changed in the middle. A method for producing a polymer. A reaction tank for storing the reaction liquid;
An external circulation line having both ends connected to the reaction vessel;
Liquid feeding means for circulating the reaction liquid in the reaction tank interposed in the external circulation line to the external circulation line;
Monomer supply means for supplying a monomer containing an α-unsaturated carboxylic acid and / or a salt thereof to the reaction solution;
A polymerization initiator supply means for supplying a redox initiator to the reaction solution;
And a reactor configured to redox polymerize the monomer and produce a carboxylic acid polymer by semi-batch operation.

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