JP2008063409A - Method for producing hydrophilic polymer particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce hydrophilic polymer particles having a fine particle diameter by dispersing a mixture finely without using power for a dispersing device. <P>SOLUTION: This method for producing the hydrophilic polymer particles comprises (1) a dispersing process of passing a mixed liquid containing an aqueous component containing a monomer and an oily component in a container 2 through a circulation line 5 installed at the container 2 and installed as mediated with a static mixer 6 by a multiple number of times in terms of the mean numbers of passing through to obtain the dispersion of dispersing the aqueous component in the oily component and (2) a reaction process of polymerizing the monomer contained in the dispersion obtained by the dispersing process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing hydrophilic polymer particles.

  Currently, various hydrophilic polymers are produced in various industrial fields. And as the manufacturing method, the reverse phase suspension polymerization method, the dispersion polymerization method, etc. are used, for example. In this reverse phase suspension polymerization method or dispersion polymerization method, the monomer (polymerizable monomer) component, the crosslinking agent, and the polymerization initiator are uniformly dissolved, and water or the like is added as necessary to uniformly dissolve the dispersant. Or it mixes in the disperse | distributed hydrophobic solvent and performs a polymerization reaction.

  By the way, in order to obtain polymer particles having a small particle diameter, it is necessary to reduce the dispersion particle diameter of the mixture containing the monomer before polymerization.

  In this regard, Patent Document 1 discloses a method for dispersing a monomer-containing mixture using a batch-type high-speed rotation high-shear type disperser.

Patent Document 2 discloses a method of dispersing a mixture containing monomers using a static mixer.
JP 2000-191817 A JP 2003-305360 A

  However, the method of dispersing the mixture using the power shown in Patent Document 1 generally has a problem that the equipment cost and the maintenance cost are expensive, and it is difficult to obtain a uniform particle size.

  Although the method of dispersing the mixture using the static mixer shown in Patent Document 2 is easy to obtain particles having a uniform particle diameter, the obtained volume average particle diameter is 5 μm or more, and particles having a smaller particle diameter are obtained. There is a problem that it is difficult to obtain.

  An object of the present invention is to finely disperse a mixture without using power in a disperser, thereby making it possible to produce hydrophilic polymer particles having a small particle size.

The method for producing hydrophilic polymer particles of the present invention that solves the above problems is as follows.
(1) A mixed liquid composed of an aqueous component and an oily component containing a monomer in a tank is passed through a circulation line attached to the tank and provided with a static mixer a plurality of times with an average number of passes to obtain an oily component. A dispersion step of obtaining a dispersion in which the aqueous component is dispersed;
(2) a reaction step of polymerizing monomers contained in the dispersion obtained in the dispersion step;
Is provided.

  According to the present invention, it is possible to finely disperse the mixture without using power to the disperser, thereby producing hydrophilic polymer particles having a minute particle size.

  Hereinafter, embodiments of the present invention will be described in detail.

[Hydrophilic polymer]
First, as the hydrophilic polymer produced according to the present invention, (i) a cationic group-containing vinyl monomer such as an amino group, an ammonium group, a pyridyl group, an imino group, or a betaine structure or a salt thereof (hereinafter referred to as “cationic monomer”). (B) Hydrophilic nonionic group-containing vinyl monomer such as hydroxy group, amide group, ester group, ether group (hereinafter referred to as “nonionic monomer”); (c) Carboxy group, Examples thereof include polymers obtained from one or more types of monomers selected from vinyl monomers containing anionic groups such as sulfonic acid groups and phosphoric acid groups and salts thereof (hereinafter referred to as “anionic monomers”). Among these, a hydrophilic polymer obtained from one or more kinds of cationic monomers and one or more kinds of nonionic monomers is preferably produced. The total amount of monomers (a) to (c) in all monomers constituting the hydrophilic polymer is preferably 70 to 100% by weight, more preferably 85 to 100% by weight.

  The hydrophilic polymer preferably has a cross-linked structure with a cross-linkable vinyl monomer having at least two reactive unsaturated groups in the molecule (hereinafter referred to as “cross-linkable monomer”). In that case, the amount of the crosslinkable monomer in all the monomers constituting the hydrophilic polymer is preferably 0.005 to 5% by weight, more preferably 0.01 to 1.0% by weight.

  Further, the hydrophilic polymer may be copolymerized with other vinyl monomers copolymerizable with the monomers (a) to (c).

<(A) Cationic monomer>
Examples of the cationic monomer (a) include (meth) acrylic acid esters and (meth) acrylamides having a dialkylamino group having 2 to 44 carbon atoms; styrene and vinyl having a dialkylamino group having 2 to 44 carbon atoms in total. N-vinyl heterocyclic compounds such as pyridine and N-vinyl imidazole; vinyl ethers; acid neutralized monomers having amino groups; monomers having amino groups are alkyl halides (1 to 22 carbon atoms), benzyl halides , Quaternized with alkyl (C1-18) sulfonic acid, aryl (C6-24) sulfonic acid, dialkyl sulfate (total C2-8), etc .; vinyl monomer having betaine structure, etc. Is done.

  Among these cationic monomers, amino group or ammonium group-containing monomers are preferable, and at least one selected from compounds represented by the following general formula (I) or (II) is more preferable.

[Wherein, R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ represent the same or different alkyl group or alkenyl group having 1 to 4 carbon atoms, and R ⁴ represents a hydrogen atom or 1 to 4 carbon atoms. Y represents an —O—, —NH— or —O—CH ₂ CH (OH) — group, Z represents a linear or branched alkylene group having 1 to 4 carbon atoms, and X Represents a conjugate base of an acid, a halogen atom or an alkyl sulfate group having 1 to 4 carbon atoms. ]

[Wherein, R ⁵ and R ⁶ are the same or different and each represents a hydrogen atom or a methyl group; R ⁷ and R ⁸ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; Indicates a conjugate base of an acid. ]
Specific examples of the compound represented by the general formula (I) include, for example, a (meth) acrylic acid ester having a dialkylamino group exemplified above, and an acid neutralized product obtained by neutralizing a (meth) acrylamide with an acid. And quaternary ammonium salts quaternized with a quaternizing agent.

  Specific examples of the compound represented by the general formula (II) include, for example, diallyl-type quaternary ammonium salts exemplified above.

  Preferred acids for obtaining the above acid neutralized product include, for example, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, organic acids having 1 to 22 carbon atoms in total. Examples of preferable quaternizing agents for obtaining the quaternary ammonium salts include general alkylating agents such as alkyl halides having 1 to 8 carbon atoms, dimethyl sulfate, diethyl sulfate, and di-n-propyl sulfate. Can be mentioned.

  Among the compounds represented by the general formulas (I) and (II), dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl ( A quaternary ammonium salt obtained by quaternizing (meth) acrylamide with the quaternizing agent described above, and dimethyldiallylammonium chloride are exemplified.

<(B) Nonionic monomer>
Examples of the nonionic monomer (b) include vinyl alcohol; (meth) acrylic acid ester or (meth) acrylamide having a hydroxyalkyl (C 1-8) group; polyethylene glycol (meth) acrylate (ethylene glycol (Meth) acrylic acid esters of polyhydric alcohols having a polymerization degree of 1 to 30); (meth) acrylamide; alkyl (1 to 8 carbon atoms) (meth) acrylamide; dialkyl (2 to 8 carbon atoms in total) (meth) Examples include acrylamide; diacetone (meth) acrylamide; (meth) acrylic acid ester having an alkyl (C 1-8) group; and (meth) acrylamide having a cyclic amide group such as N- (meth) acryloylmorpholine. .

  Among these nonionic monomers, (meth) acrylamide monomers represented by the following general formulas (III) and (IV), and (meth) acrylic acid having the above hydroxyalkyl (C1-8) group Preferred are esters and (meth) acrylic acid esters of the above polyhydric alcohols.

[Wherein, R ¹ represents a hydrogen atom or a methyl group, and R ⁹ and R ¹⁰ are the same or different and each represents a hydrogen atom or a linear or branched chain having 1 to 8 carbon atoms, and has a hydroxy group. An alkyl group or an alkenyl group which may be present is shown. ]

[Wherein, R ¹ represents a hydrogen atom or a methyl group, A ¹ and A ² are the same or different, and each is represented by the formula — (CH ₂ ) _n — (n represents an integer of 2 to 6). represents a group, B is -O- or -CH ₂ - shows a group. ]
Examples of the monomer represented by the general formula (III) include (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N- Examples thereof include n-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N-isobutyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide and the like.

  Examples of the monomer represented by the general formula (IV) include N- (meth) acryloylmorpholine.

<(C) Anionic monomer>
Examples of the anionic monomer (c) include, for example, a carboxylic acid monomer having a polymerizable unsaturated group and an acid anhydride thereof (when two or more carboxyl groups are contained in one monomer); Examples thereof include a sulfonic acid monomer having a group; a phosphoric acid monomer having a polymerizable unsaturated group. The anionic group may be neutralized with a basic substance to an arbitrary degree of neutralization. In this case, all the anionic groups in the polymer or a part of the anionic groups will form a salt.

  Among these anionic monomers, the above-mentioned polymerizable unsaturated group-containing carboxylic acid monomer and its acid anhydride (provided that one monomer has two or more carboxyl groups), the above-mentioned polymerizable property Of these, sulfonic acid monomers having an unsaturated group are preferred.

<Crosslinkable monomer>
Examples of the crosslinkable monomer include (meth) acrylic acid esters of polyhydric alcohols; acrylamides; divinyl compounds; polyallyl compounds; (meth) acrylic acid esters of unsaturated alcohols, and the like.

  Among these crosslinkable monomers, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene, pentaerythritol triallyl ether, and pentaerythritol tetraallyl ether are preferable.

<Other monomers>
Examples of other vinyl monomers that can be copolymerized with the monomers (a) to (c) constituting the hydrophilic polymer of the present invention include (meth) acrylic acid derivatives.

[Method for producing hydrophilic polymer]
The method for producing the hydrophilic polymer of the present invention is preferably a radical polymerization initiator (for example, the following peroxide or 2, 2) using the monomers (a) to (c) and optionally a crosslinkable monomer. -Azobis compound such as azobisisobutyronitrile) in the presence of a reverse phase suspension polymerization method using a hydrophobic solvent.

  Specifically, first, in a reaction tank, an aqueous solution in which a monomer and an initiator as an aqueous component are uniformly mixed and a hydrophobic solvent as an oily component are mixed to prepare a mixed solution. At this time, a dispersant is used if necessary. In addition, adjustment of a liquid mixture may be performed in another tank and it may be moved to a reaction tank.

  Next, this mixed liquid is passed through a circulation line attached to the reaction tank and provided with a static mixer at a number of average passes, and a dispersion liquid in which an aqueous solution is dispersed in a hydrophobic solvent in the reaction tank Is obtained (dispersing step).

  Then, the temperature of the reaction vessel is raised under an inert gas such as nitrogen, and the monomer contained in the dispersion is polymerized in the reaction vessel (polymerization step). Although depending on the type of monomer, the polymerization initiation temperature is usually about 40 to 90 ° C., and the reaction time is usually about 1 to 24 hours. In addition, after allowing the mixed solution to pass through the circulation line a plurality of times with an average number of passages, the dispersion may be recovered in another reaction vessel to cause a polymerization reaction.

  After the polymerization reaction, the hydrophobic solvent is distilled off to obtain a hydrophilic polymer. At this time, it is preferable to perform dehydration in advance for the purpose of facilitating the distillation of the hydrophobic solvent.

<Hydrophobic solvent>
Examples of the hydrophobic solvent used in the method for producing the hydrophilic polymer of the present invention include hydrocarbon solvents such as hexane, cyclohexane, heptane, octane, benzene, toluene, xylene, and ethylbenzene; halogens such as carbon tetrachloride and dichloroethane. Hydrocarbon solvents; mineral oil such as Isobar.

  Of these hydrophobic solvents, hydrocarbon solvents are preferably used, and hexane and cyclohexane are more preferable.

  The amount of the hydrophobic solvent is preferably 1 to 20 times by weight, more preferably 1 to 10 times by weight based on the total amount of monomers.

<Dispersant>
Examples of the dispersant used in the method for producing the hydrophilic polymer of the present invention include sorbitan monostearate, sorbitan monopalmitate, polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxy cellulose, carboxymethyl cellulose, carboxyethyl cellulose, sucrose fatty acid ester, Examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, alkyl trimethyl ammonium chloride, dialkyl dimethyl ammonium chloride, alkyl sulfate, polyoxyethylene alkyl ether sulfate and the like. One or more of these dispersants may be used in combination.

  Among these dispersants, sorbitan monostearate and sucrose fatty acid ester are preferable from the viewpoint of dispersion stability.

  The amount of the dispersant is preferably 0.3 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the total monomers.

<Polymerization initiator>
As the polymerization initiator used in the method for producing the hydrophilic polymer of the present invention, a radical polymerization initiator is preferably used. Examples of such polymerization initiators include peroxides that are uniformly dissolved in the monomer component, organic or inorganic peracids or salts thereof, redox-based compounds that are azobis compounds alone or in combination with a reducing agent.

  Among these polymerization initiators, in particular, t-butyl peroxide, benzoyl peroxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2 , 2'-Azobis (2- (5-methyl-2-imidazolin-2-yl) dihydrochloride, sodium persulfate, potassium persulfate or ammonium persulfate alone, potassium persulfate or ammonium persulfate persulfate and triethylamine A combination with a tertiary amine such as triethanolamine or dimethylaniline is preferred.

  The amount of the polymerization initiator increases the degree of polymerization of the polymer chain of the main chain, reduces the proportion of polymer chains that are not crosslinked, makes it difficult to dissolve in water and hydrophobic solvents, and increases the reaction rate of the polymerization reaction, From the viewpoint of reducing the residual monomer amount, 0.01 to 5 parts by weight is preferable, 0.5 to 3 parts by weight is more preferable, and 0.1 to 1 part by weight is particularly preferable with respect to 100 parts by weight of the total monomers.

<Static mixer>
As a static mixer, from the viewpoint of excellent mixing properties, for example, a contraction / split type static mixer (trade name: Disperse-kun, manufactured by Fujikin Co., Ltd.) can be used. This static mixer can be configured by providing a plurality of units each having the same flow path hole configuration so that the flow path holes communicate with each other.

  The inner diameter of the flow path constriction portion of the flow path hole is preferably 0.2 to 20 mm, more preferably 0.5 to 10 mm, and further preferably 0.5 to 5 mm.

<Average particle size of dispersion>
The volume average particle size of the aqueous solution in the dispersion is preferably from 1 μm to less than 5 μm, more preferably from 1.5 to 4.8 μm, and more preferably from 2 to 4 μm, from the viewpoint of having an appropriate surface area and feel when making a product such as cosmetics. .5 μm is particularly preferable. This can be measured by a laser diffraction / scattering particle size distribution analyzer (for example, LS-230, manufactured by Beckman Coulter, Inc.).

<Average number of times that the liquid mixture passes through>
The average number of passes of the mixed solution to the static mixer is preferably 3 times or more, more preferably 4 times or more from the viewpoint of producing fine and uniform polymer particles. The above is particularly preferable. On the other hand, from the viewpoint of shortening the cycle time of polymerization, it is preferably 30 times or less, more preferably 20 times or less, and particularly preferably 10 times or less.

  The average number of passages N (−) is obtained by the following equation when the amount of liquid in the reaction system is V (L), the flow rate of the circulation pump is Q (L / min), and the circulation time is T (min). Can do.

Average number of passes N = Q × T / V
<Pressure loss of static mixer>
When the static mixer is composed of a plurality of units as described above, the pressure loss per unit between the inlet and the outlet of the static mixer is reduced from the viewpoint of producing fine polymer particles. The pressure is preferably 0.01 MPa or more, and more preferably 0.02 MPa or more. On the other hand, it is preferably 0.1 or less, more preferably 0.08 MPa or less, from the viewpoint of reducing the power for circulating the mixed liquid.

  Here, there is a correspondence between the pressure loss of the static mixer and the volume average particle diameter of the aqueous solution in the dispersion. By setting the pressure loss between the inlet and outlet of the static mixer to a constant value, the dispersion can be achieved. The volume average particle diameter of the aqueous solution in the liquid can be freely controlled to correspond to the pressure loss.

  Hereinafter, the test evaluation in which hydrophilic polymer particles were produced by reverse phase suspension polymerization will be described.

(Example)
<Polymer production equipment>
FIG. 1 shows a polymer production apparatus A used in this example.

  This polymer production apparatus A includes a monomer tank 1 for preparing an aqueous monomer solution equipped with a stirrer, a thermometer and a cooler, and a reaction tank 2 for polymerization reaction equipped with a stirrer, a thermometer and a cooler. ing.

  A monomer aqueous solution supply pipe 3 extends from the monomer tank 1 toward the reaction tank 2.

  The reaction tank 2 is provided with a circulation line 4, and the circulation line 4 is provided with a circulation pump 5 for circulating the fluid. Further, between the circulation pump 5 and the reaction tank 2 in the circulation line 4, a static mixer 6 (trade name: manufactured by Fujikin Co., Ltd., trade name) is interposed.

  This static mixer 6 is of a contracted flow / split type, and as shown in FIG. 2, five units composed of two disk-shaped first and second elements 21 and 22 are connected. It is a thing.

  As shown in FIG. 2A, the first element 21 has four flow passage holes 23 arranged in a square of 2 × 2 at the center portion, while the second element 22 has As shown in FIG. 2 (b), a total of five flow path holes 23 are formed in the central portion, one at the center and four arranged in a square of 2 × 2 so as to surround it.

  As shown in FIG. 3, each flow path hole 23 of the first and second elements 21 and 22 has a constricted part of a cylindrical hole having a small inner diameter of the flow path at the center part, and each of both sides thereof is an opening. It is formed in a shape that expands in the shape of a truncated cone. In FIG. 3, the opening diameter represents the maximum hole diameter d <b> 1 of the flow path hole 23, and the contraction portion flow path inner diameter represents the minimum hole diameter d <b> 2 of the flow path hole 23.

  These first and second elements 21 and 22 are positioned by the positioning portion 24 so that the flow passage holes 23 of the first element 21 and the three flow passage holes 23 of the second element 22 communicate with each other. The square diagonal lines having the four channel holes 23 arranged in a square are apposed so as to be shifted by 45 °.

  In the static mixer 6, as a result, the fluid that has been circulated by being compressed in one flow path hole 23 of the first element 21 is divided by the second element 22 as shown in FIG. In the second element 22, the fluid from the plurality of flow path holes 23 of the first element 21 flows into the flow path holes 23, mixes and contracts and circulates. The fluid is supplied to the first element 21 of the next unit, and the fluid flows by repeating the division and the contraction. Note that the number of units, the number of channel holes, and the channel inner diameter of the static mixer 6 can be selected as appropriate.

<Example 1>
A 300 L reaction vessel 2 was charged with 39 kg of cyclohexane and 0.044 kg of a dispersant (sucrose fatty acid ester: product name S-770, manufactured by Mitsubishi Chemical Foods Co., Ltd.). Further, in a 100 L monomer tank 1, 1.4 kg of an 80% aqueous solution of dimethylaminoethyl methacrylate diethyl sulfate (MOEDES: manufactured by Nitto Chemical Industry Co., Ltd.), N, N-dimethylacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) ) 3.3 Kg, polyethylene glycol dimethacrylate (NK-9G: manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.001 Kg, ion-exchanged water 6.5 Kg and initiator (manufactured by Wako Pure Chemical Industries, Ltd., product name V-50) ) 0.03 kg was charged.

  After transferring the monomer aqueous solution containing the initiator from the monomer tank 1 to the stirring reaction tank 2, the mixture was mixed for 10 minutes to obtain a mixed solution.

  Next, the mixed solution in the reaction tank 2 was circulated in the circulation line 4. In the circulation line 4, each unit is constituted by the first and second segments 21 and 22 in which the flow path inner diameter d2 of each flow passage hole 23 is 2.0 mm, and the unit is constituted by five units. Although the static mixer 6 is provided, when the flow rate of the circulation pump 5 is 5 L / min, the pressure loss between the inlet and the outlet of the static mixer 6 is 0.14 MPa (pressure per unit). Loss was 0.03 MPa). Further, the average number of times the liquid mixture passed through the static mixer 6 was 8 times, and the temperature of the liquid mixture in the circulating reaction tank 2 was adjusted to 30 ° C.

  After the dispersion of the mixed liquid is completed, the temperature of the dispersion liquid in the reaction vessel 2 is increased to 54 to 57 ° C. and a polymerization reaction is performed for 40 minutes, and then the temperature of the dispersion liquid is further increased to 70 ° C. Was done.

  After completion of the polymerization, water was separated and then cyclohexane was distilled off to obtain 3.9 kg of hydrophilic polymer.

  The obtained hydrophilic polymer had a volume average particle size (hereinafter referred to as “average particle size”) of 4.3 μm. In addition, the average particle diameter was measured with the laser diffraction scattering type particle size distribution measuring apparatus (Beckman Coulter company make: LS-230).

<Example 2>
A static mixer 6 having a contracted flow channel inner diameter d2 of 1.0 mm is used, the flow rate of the circulation pump 5 is 1.5 L / min, and the pressure loss in the static mixer 6 is 0.24 MPa (per unit). And a hydrophilic polymer was obtained in the same manner as in Example 1 except that the average number of times the liquid mixture passed through the static mixer 6 was six.

  The average particle size of the obtained hydrophilic polymer was 2.2 μm.

<Example 3>
Using a static mixer 6 with a constricted flow passage inner diameter d2 of 3.5 mm, the flow rate of the circulation pump 5 is 11 L / min, and the pressure loss in the static mixer 6 is 0.14 MPa (pressure per unit). A hydrophilic polymer was obtained in the same manner as in Example 1 except that the loss was 0.03 MPa.

  The average particle size of the obtained hydrophilic polymer was 4.4 μm.

<Example 4>
The hydrophilic polymer was obtained in the same manner as in Example 2 except that the flow rate of the circulation pump 5 was 2 L / min and the pressure loss in the static mixer 6 was 0.4 MPa (pressure loss per unit: 0.08 MPa). Obtained.

  The average particle size of the obtained hydrophilic polymer was 2.1 μm.

(Comparative example)
In Comparative Examples 1 to 3 below, the mixed liquid in the reaction tank 2 was dispersed without being circulated in the circulation line 4. That is, the mixed liquid in the reaction tank 2 is sent to the static mixer 6 using the circulation pump 5, and the dispersion liquid dispersed in the static mixer 6 is not returned to the reaction tank 2, but another receiving tank (not shown). I received it. Then, after the total amount of the mixed liquid in the reaction tank 2 had been sent, the dispersion in the receiving tank was returned to the reaction tank again for polymerization.

<Comparative Example 1>
A hydrophilic polymer was obtained in the same manner as in Example 1 except that the liquid mixture was passed through the static mixer 6 only once.

  The average particle size of the obtained hydrophilic polymer was 8.1 μm.

<Comparative example 2>
A hydrophilic polymer was obtained in the same manner as in Example 3 except that the liquid mixture was passed through the static mixer 6 only once.

  The average particle diameter of the obtained hydrophilic polymer was 6.1 μm.

<Comparative Example 3>
A hydrophilic polymer was obtained in the same manner as in Example 4 except that the liquid mixture was passed only once through the static mixer 6. The pressure loss in the static mixer 6 was 0.55 MPa (pressure loss per unit 0.11 MPa).

  The average particle diameter of the obtained hydrophilic polymer was 6.7 μm.

  As described above, the present invention is useful for producing a micronized hydrophilic polymer.

It is explanatory drawing which shows the structure of a polymer manufacturing apparatus. (A) is a top view of the 1st element of 1 unit of a static mixer, (b) is a top view of a 2nd element. It is a figure which shows the shape of a flow-path hole. It is explanatory drawing which shows the contraction flow and division | segmentation of the fluid in a static mixer.

Explanation of symbols

2 Reaction tank 4 Circulation line 6 Static mixer 23 Channel hole

Claims (5)

(1) A mixed liquid composed of an aqueous component and an oily component containing a monomer in a tank is passed through a circulation line attached to the tank and provided with a static mixer a plurality of times with an average number of passes to obtain an oily component. A dispersion step of obtaining a dispersion in which the aqueous component is dispersed;
(2) a reaction step of polymerizing monomers contained in the dispersion obtained in the dispersion step;
A method for producing hydrophilic polymer particles comprising:   The method for producing hydrophilic polymer particles according to claim 1, wherein the volume average particle size of the aqueous component in the dispersion is 1 μm or more and less than 5 μm.   The method for producing hydrophilic polymer particles according to claim 1 or 2, wherein, in the dispersion step, the average number of times the mixed solution passes through the circulation line is 3 or more. The static mixer is configured such that a plurality of units each having the same flow path hole configuration are provided so that the flow path holes communicate with each other.
The hydrophilic polymer particles according to any one of claims 1 to 3, wherein in the dispersion step, a pressure loss per unit between an inlet and an outlet of the static mixer is 0.01 to 0.1 MPa. Manufacturing method.   In the dispersion step, the pressure loss between the inlet and the outlet of the static mixer is set to a constant value, and the volume average particle size of the aqueous component in the dispersion is controlled to correspond to the pressure loss. Item 5. A method for producing hydrophilic polymer particles according to any one of Items 1 to 4.

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