JP2678067B2 - Method for producing hydrophilic polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a hydrophilic polymer, particularly a water-swellable water-absorbent polymer. More specifically, the present invention relates to a method in which a hydrogel of a hydrophilic polymer is less likely to adhere to a reaction vessel during the production of a hydrophilic polymer, and therefore the hydrophilic polymer can be stably produced with good productivity.

[Problems to be Solved by Prior Art and Present Invention]

Conventionally, cross-linked polymers mainly composed of acrylic acid or a salt thereof, paper diapers, hygiene products, agricultural and horticultural soil improver,
It is widely used as a dehydrating agent.

Known as one of the methods for producing these crosslinked polymers is so-called reverse phase suspension polymerization or reverse phase emulsion polymerization, which is carried out by suspending or emulsifying an aqueous monomer solution in a hydrophobic organic solvent.

However, in the conventional production method, in the course of the polymerization, the adhesive hydrous gel material adheres to the side wall of the reaction vessel to lower the yield and to improve the workability when taking out the hydrophilic polymer from the reaction vessel. Causing a decline. Furthermore,
Such polymer deposits grow as the number of reactions increases, and regular washing operations are required, which significantly reduces the productivity of the hydrophilic polymer. Such troubles are particularly remarkable on the surface of the inner wall of the reaction vessel, which is repeatedly and repeatedly contacted with the suspension (emulsified) liquid mainly by the gas which is an inert gas.

In order to solve the above problems, many methods have been proposed in which a specific dispersant is used when a hydrophilic polymer is obtained by reverse phase suspension polymerization or reverse phase emulsion polymerization. (JP-A-57-74309, JP-A-61-231003, JP-A-61-231004, etc.) However, the method by selecting such a dispersant improves adhesion of hydrous gel to some extent. However, as the same reaction vessel is continuously used, the deposits grow on the side wall, and as a result, the flow state of the liquid in the reaction vessel changes and the particle size distribution and the amount of secondary aggregation of particles change. The actual situation is that satisfactory results cannot be obtained in continuous production such as giving.

[Means for solving the problem]

The present invention has been made in view of the above circumstances, and the above problems have been solved all at once by the method for producing a hydrophilic polymer provided by the present invention.

That is, according to the present invention, an aqueous solution of a monomer component is dispersed in a polymerization-inert hydrophobic organic solvent in the presence of a dispersant in a reaction vessel equipped with a rotary stirring blade to perform reverse phase suspension polymerization or reverse phase polymerization. When a hydrophilic polymer is produced by emulsion polymerization, a repeated repeated contact surface (hereinafter, simply referred to as repeated repeated contact surface) of at least a suspension (emulsion) liquid and a gas on the inner wall of the reaction vessel is represented by R _max . The present invention relates to a method for producing a hydrophilic polymer, which comprises adjusting the surface roughness to 3 μm or less, and constantly cooling at least the repeated contact surface from the back surface with cooling water at a temperature of 60 ° C. or less. . The suspension (emulsification) liquid refers to a liquid product in which an aqueous solution of a monomer component or a polymerization reaction product thereof is dispersed (or emulsified) in a hydrophobic organic solvent. . Hereinafter, the liquid material is collectively referred to as a suspension.

 Hereinafter, the present invention will be described in detail.

The reaction vessel used in the present invention is not particularly limited in shape as long as it has a rotary stirring blade, and at least the repeating contact surface of the inner wall is adjusted to have a surface roughness represented by R _max of 3 μm or less. Further, at least the cooling device is provided on the back surface of the repeated contact surface. The repetitive repeated contact surface in the present invention means that the suspension and the gas which is mainly an inert gas are alternately and repeatedly contacted due to the vertical movement of the suspension accompanying the stirring operation during the polymerization. It refers to the surface to which the physical force for removing the adhering material due to the movement of the stirrer does not reach, and usually refers to the place where the most abundant material occurs.
Such repeated contact surface is generally near the interface between the suspension and the gas, but it depends on the properties and morphology of the reactants and the stirring conditions. Can extend to Therefore, the repeated repeated contact surface should be determined in consideration of the properties, morphology and stirring conditions of the reaction product.

Thus, the reaction vessel used in the production method of the present invention is such that at least the inner surface of the reaction vessel is repeatedly and repeatedly contacted with the suspension and the gas, and the contact surface is adjusted to the specified surface roughness.
In addition, it is essential that at least the back surface of the contact surface has a structure capable of cooling (hereinafter referred to as a cooling structure). In some cases, the adjustment of the surface roughness is suspended. It may be the entire contact surface with the liquid or the entire inner wall of the reaction vessel. On the other hand, since the suspension requires a heating operation in the process of producing the hydrophilic polymer, a heating device capable of supplying a sufficient amount of heat for the progress of the polymerization reaction must be installed below the contact surface. Not
Therefore, even if the cooling structure is maximum, it must be the entire surface except the installation surface of the heating device.

Various methods can be used to equip the back surface of the reaction vessel with a cooling structure, such as a water sprinkling device, a jacket capable of pouring / draining at a constant flow rate, and a spiral tube. Further, when the suspension has a large adherence and is markedly adhered to the stirrer, a cooling water passage is installed inside the rotating stirring blade so that the surface of the rotating stirring blade can be cooled from the inside by the cooling water. The stirring blade itself may also be provided with a cooling structure.

In the present invention, at least the repeated contact surface of the inner wall of the reaction vessel has a surface roughness represented by R _max of 3 μm.
It must be: Surface roughness R _max here
Is the R _max specified in JIS B 0601. R
_{When max} exceeds 3 μm, a remarkable effect of preventing deposits cannot be obtained. Particularly remarkable effect of preventing deposits is R _max of 0.5μ
This can be achieved by setting the thickness to m or less, and more preferably 0.1 μm or less. It is possible to adjust R _max to 3 μm or less by a buffing method, and it is preferable to carry out immersion electrolytic polishing or electrolytic composite polishing after buffing in order to reduce R _max to obtain a smooth surface. Such adjustment of the surface roughness must be performed on at least the repetitive repeating contact surface of the reaction vessel, but if necessary, the surface other than the repetitive repeating contact surface and the surface of the rotary stirring blade are also defined as above. The surface roughness may be adjusted or a suitable adjustment such as fluororesin coating may be performed. However, from the viewpoint of durability, it is preferable that the above-mentioned regulation of the surface roughness is performed on the entire inner wall of the reaction vessel in order to prevent the reaction from adhering to the entire inner wall of the reaction vessel. It is more preferable that the surface of the rotary stirring blade is further formed.

The reaction vessel used in the present invention has a surface roughness and a cooling structure on the back surface as described in detail above, and the surface roughness and the cooling structure on the back surface are suitable for the wall surface of the hydrous gel in the polymerization process. It exerts a remarkable synergistic effect in preventing adhesion, and if either one of the surface roughness and the back surface cooling structure is lacking, a satisfactory result cannot be obtained.

The specific embodiment of the reaction vessel used in the present invention is as shown in FIG.

Thus, in the production method of the present invention, at least one of the reaction vessels is used for polymerizing the monomer to be a hydrophilic polymer by the inverse phase suspension polymerization or the inverse phase emulsion polymerization using the reaction vessel described in detail above. This is achieved by conducting a polymerization reaction by a well-known procedure to form a hydrophilic polymer while cooling the specified repeating contact surface from the back surface with cooling water having a temperature of 60 ° C. or less. In order to more effectively exhibit the effect of preventing deposits, it is preferable that the cooling from the back surface is performed over the entire upper part of the reaction container including the repeated contact surface.
Further, when adherence to the rotary stirring blade is observed, the surface of the rotary stirring blade may be cooled from the inside by passing cooling water of 60 ° C. or lower through a cooling water passage installed inside the rotary stirring blade.

If the temperature of the cooling water exceeds 60 ° C, the sufficient effect of preventing deposits cannot be obtained. The lower the temperature of the cooling water, the greater the effect, and it is preferably 50 ° C or lower, more preferably 40 ° C or lower, and further preferably 30 ° C or lower. Cooling with cooling water must be performed at a time when the adhesiveness becomes most remarkable during the period from the start of the polymerization reaction to the end of the polymerization reaction. This time depends on the composition of the monomer components. However, considering the higher effect and the work complexity, it is preferable to set the whole period from the reaction start to the end of the polymerization reaction, and also during the operation of taking out the suspension of the hydrophilic polymer after the completion of the polymerization reaction. It is preferably cooled.

The reaction vessel used in the present invention is preferably provided with an inert gas introducing device so as to maintain an atmosphere inert to the radical polymerization reaction during the polymerization. During the polymerization, a reflux condenser may be provided in the upper part of the reaction vessel to condense the water vaporized due to the heat of the polymerization reaction, or an inert gas may be introduced into the polymerization vessel to release the water out of the system. May be.

The monomer component used in the present invention is a water-soluble or water-swellable polymer by reverse phase suspension polymerization or reverse phase emulsion polymerization, and a water-swellable polymer is particularly preferable. . The water-swellable polymer has a cross-linking structure. The cross-linking structure includes a water-soluble monomer (A) and a cross-linkable monomer (B) having two or more polymerizable double bonds in the molecule. Examples thereof include a cross-linking structure by copolymerization and a cross-linking structure by reaction with a reactive cross-linking agent (C) having two or more reactive functional groups capable of reacting with a functional group of a monomer, such as starch, cellulose and polyvinyl alcohol. A cross-linked structure may be formed by simultaneously forming a graft bond or a complex by polymerizing a water-soluble monomer in an aqueous solution in the presence of the hydrophilic polymer.

Examples of the water-soluble monomer (A) in the present invention include (meth) acrylic acid, crotonic acid, maleic acid (anhydrous), fumaric acid, itaconic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) ) Acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid and the like anionic monomers and salts thereof; N, N-dimethylaminoethyl (meth) acrylate , N, N-Dimethylaminopropyl (meth) acrylate, cationic monomers such as N, N-dimethylaminopropyl (meth) acrylamide and quaternary compounds thereof; (meth) acrylamide, N
-A unit amount containing a nonionic hydrophilic group such as substituted (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, methoxy polyethylene glycol (meth) acrylate The body and the like can be mentioned, and one or more of these can be used.

Examples of the crosslinkable monomer (B) having two or more polymerizable double bonds in the molecule used in the present invention include, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1 , 4-butanediol, 1,5-pentanediol, 1,6-hexanediol,
Di (meth) acrylates such as neopentyl glycol, glycerin, trimethylolpropane and pentaerythritol; tri (meth) acrylates such as glycerin, trimethylolpropane and pentaerythritol, N, N '
-Methylenebis (meth) acrylamide, triallylamine, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, poly (meth) acrylic acid salt of polyvalent metal, etc. are exemplified, and one or more of them are listed. Can be used. Further, as the reactive cross-linking agent (C) having two or more reactive functional groups capable of reacting with the functional group of the monomer, for example, the water-soluble monomer (A) has a carboxyl (carboxylate) group. When having, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, triethanolamine, polyoxypropylene, oxyethyleneoxypropylene block copolymer, pentaerythritol Polyhydric alcohols such as sorbitol, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether,
Polyvalent polyglycidyl ethers, sorbitol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, propylene glycol diglycidyl ethers, polypropylene glycol diglycidyl ethers, and other polyvalent glycidyl compounds; 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 1,6-hexamethylenediethyleneurea, diphenylmethane-bis-4,4'-N, N'-
Polyhydric aziridines such as diethylene urea; haloepoxy compounds such as epichlorohydrin, α-methylchlorohydrin; polyhydric aldehydes such as glutaraldehyde, glyoxal; ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, Polyvalent amines such as pentaethylenehexamine and polyethyleneimine; Polyisocyanates such as 2,4-toluylene diisocyanate and hexamethylene diisocyanate; aluminum chloride, magnesium chloride, calcium chloride, aluminum sulfate, magnesium sulfate, calcium sulfate Preferred are polyvalent metal salts such as

In order to obtain a water-swellable polymer among the above-mentioned monomer components, the water-soluble monomer (A) is (meth) acrylic acid, 2- (meth) acryloylethanesulfonic acid, 2-
(Meth) acrylamido-2-methylpropanesulfonic acid, salts of these unsaturated acids, N, N-dimethylaminoethyl (meth) acrylate and its quaternary compounds, methoxypolyethylene glycol (meth) acrylate, and (meth) acrylamide It is preferable to use one or more water-soluble monomers (A) selected from these.
And a crosslinkable monomer (B) having two or more polymerizable double bonds in the molecule, the crosslinkable monomer (B) is 0.001 to 50 mol% with respect to the water-soluble monomer (A). The monomer components used in the following ratio are particularly preferable. As the crosslinkable monomer (B), one kind or two kinds can be used from the above-mentioned crosslinkable monomers. At this time, if the amount of the crosslinkable monomer (B) used is less than 0.001 mol% with respect to the water-soluble monomer (A), the resulting water-swellable polymer is soft and sticky,
Even when subjected to mechanical shearing force, they stick together and form a lump that is difficult to subdivide. On the other hand, if it exceeds 50 mol%, the water swelling polymer obtained will have low water absorption and ion exchange capacity.

The dispersant used when performing the reverse phase suspension polymerization or the reverse phase emulsion polymerization of the present invention is not particularly limited, and examples thereof include sorbitan fatty acid ester, glycerin fatty acid ester, sucrose fatty acid ester, polyglycerin fatty acid ester, and polyoxyethylene. Nonionic surfactants such as alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene sorbitan fatty acid esters, cellulose derivatives, fibrin derivatives such as cellulose ethers, α
Examples thereof include a carboxyl group-containing polymer such as a copolymer of olefin and maleic anhydride or a derivative thereof.

Of these, nonionic surfactants of HLB2 to 14 are preferred, and sorbitan fatty acid ester of HLB2 to 14, sucrose fatty acid ester, polyoxyethylene alkyl ether, and polyoxyethylene alkylaryl ether are preferred. You may use together or 2 or more types. Although the amount used varies depending on the polymerization conditions, it is generally 0.05 to 30% by weight, preferably 0.5 to 10% by weight, based on the monomer components.

Examples of the hydrophobic organic solvent used in the present invention include n
-Pentane, n-hexane, n-heptane, n-octane, cyclohexane, cyclooctane, methylcyclohexane, decalin, benzene, ethylbenzene, toluene, xylene, dichlorobenzene, dibromobenzene,
Tetrachloroethylene, perchlorethylene, carbon tetrachloride, methylene chloride, liquid paraffin, kerosene,
Mineral oil, animal and vegetable oils and the like can be mentioned, and one kind or a mixture of two or more kinds thereof can be used. Particularly preferred are n-hexane, cyclohexane, toluene, xylene, liquid paraffin and kerosene. The ratio of the hydrophobic organic solvent to the aqueous monomer solution is generally 1: 1 to 4: 1 from the viewpoint of removing the heat of polymerization, controlling the temperature, or stabilizing the dispersion.

Known polymerization initiators can be used as the polymerization initiator for the inverse phase suspension polymerization or the inverse phase emulsion polymerization of the monomer component in the present invention. For example, the polymerization initiator in the case of carrying out reverse phase suspension polymerization is water-soluble, and examples thereof include persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; hydrogen peroxide, t
-Hydroperoxides such as butyl hydroperoxide and cumene hydroperoxide; azo compounds such as 2,2'-azobis-2-amidinopropane dihydrochloride. These polymerization initiators can be used as a mixture of two or more, and further, even if a redox type initiator obtained by combining with a reducing agent such as sulfite, 1-ascorbic acid, ferric salt is used. Good.

Alternatively, the polymerization initiator in the case of carrying out reverse phase emulsion polymerization is an oil-soluble initiator, and examples thereof include peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl peroxybenzoate, and t-butyl peroxypivalate; azo. Examples thereof include azo compounds such as bisisobutyronitrile and azobis (2,4-dimethylvaleronitrile).

These polymerization initiators are usually used in an amount of 0.001-5
It is about mol%, and its optimum amount is determined by the kind of the initiator and the polymerization conditions.

The thus obtained suspension or emulsion of the hydrophilic polymer can be used as it is as an absorbent, a water retention agent, a coagulant, a dispersant, a thickener, an adsorbent, etc., but after a separation / drying step. It is preferred to remove most of the hydrophobic organic solvent and water. As a specific method of this separation / drying step, a method of azeotropically distilling water and a hydrophobic organic solvent,
When the hydrophilic polymer is a water-swellable polymer, there is a method in which the hydrogel polymer is filtered and then dried by a normal hot air dryer, a reduced pressure dryer, a fluidized bed dryer or the like. The hydrophilic polymer obtained by drying in this manner is an absorbent for sanitary materials such as paper diapers, a water retention agent for agricultural and horticultural use, an ion exchange resin,
It is effective as a desiccant, a water blocking agent, a coagulant, a dispersant, a thickener and the like.

〔The invention's effect〕

According to the production method of the present invention, since the inner wall of the reaction vessel used for the polymerization reaction is adjusted to a specific surface state and is cooled from the back surface, the adjustment of the surface state and the cooling from the back surface are the reaction vessels. It exerts a remarkable synergistic effect in preventing the adhesion of reactants to the inner wall. Therefore, even if the number of reactions is repeated, there is almost no decrease in the effective volume of the reaction vessel, and the regular cleaning work can be significantly reduced. Therefore, according to the production method of the present invention, it is possible to greatly improve the productivity of the hydrophilic polymer by the reverse phase suspension polymerization or the reverse phase emulsion polymerization.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 An inner diameter of 280 mm having a cooling water jacket as a cooling structure and a heating jacket located below it on the outside, and equipped with a stirring blade, a reflux condenser, a thermometer, a nitrogen gas introducing pipe and a dropping funnel, The surface roughness R _max was adjusted to 0.1 μm on the entire inner wall of the stainless steel reaction vessel of volume 20 by Hitachi Shipbuilding type electrolytic composite polishing. (See FIG. 1) Cyclohexane 10 and 30 g of sorbitan monostearate (HLB = 4.7) as a dispersant were charged into this reaction vessel, and nitrogen gas was blown thereinto to remove dissolved oxygen. Meanwhile, in a separate flask, sodium acrylate (846 g), acrylic acid (216 g) and N, N'-methylenebisacrylamide were used.
0.555 g was dissolved in 1970 g of ion-exchanged water to prepare an aqueous solution of a monomer component having a monomer concentration of 35% by weight.

After 1.5 g of potassium persulfate was added to and dissolved in the aqueous solution of the monomer component, nitrogen gas was blown in to remove oxygen dissolved in the aqueous solution. Next, the aqueous solution of the monomer component in the flask was added to the reaction container and dispersed by stirring. Then, the cooling water jacket is 20 ℃
The cold water of 65 ° C. is poured into the heating jacket to start the polymerization reaction, and the polymerization reaction is completed by maintaining this state for 2 hours to obtain a suspension of the hydrophilic polymer. The suspension was discharged from the reaction vessel to complete one polymerization operation. Thereafter, the same polymerization operation as above was continuously repeated to carry out polymerization 20 times in total. After the completion of 20 times of polymerization, no deposit was found on the inner wall of the reaction vessel at the place corresponding to the repeatedly repeated contact surface.

Comparative Example 1 The same operation as in Example 1 was repeated except that cooling water at 20 ° C. was not passed through the cooling water jacket. After the completion of 20 times of polymerization, a large amount of deposits was observed on the inner wall of the reaction vessel at the place corresponding to the repeated repeated contact surface. (See FIG. 2) Example 2 The same operation as in Example 1 was repeated except that the inner wall of the reaction vessel was adjusted to have a surface roughness R _{max of} 0.7 μm by # 200 buffing. After the completion of 20 times of polymerization, almost no deposit was observed on the inner wall of the reaction vessel at the position corresponding to the repeated contact surface.

Example 3 The same operation as in Example 1 was repeated except that cold water of 40 ° C. was flown through the cooling water jacket.
After the completion of 20 times of polymerization, no deposit was found on the inner wall of the reaction vessel at the place corresponding to the repeatedly repeated contact surface.

Comparative Example 2 The same operation as in Example 1 was repeated except that the reaction vessel having the inner wall surface roughness R _{max of} 3.5 μm was used in Example 1. After the completion of 20 times of polymerization, a large amount of deposit was observed on the inner wall of the reaction vessel at a position corresponding to the repeated contact surface.

Example 4 The same operation as in Example 1 was repeated except that cooling water of 50 ° C. was flowed through the cooling water jacket. After the completion of 20 times of polymerization, a slight amount of deposit was observed on the inner wall of the reaction vessel at the position corresponding to the repeated contact surface.

Comparative Example 3 In Example 1, 20 ° C. was poured into the jacket for cooling water.
The same operation as in Example 1 was repeated except that the cooling water in Example 1 was replaced with warm water at 65 ° C. After the completion of 20 times of polymerization, a large amount of deposits was observed on the inner wall of the reaction vessel at the place corresponding to the repeated repeated contact surface.

Example 5 In Example 4, except that a reaction vessel whose inner wall was adjusted to a surface roughness R _max 0.7 μm by buffing # 200 was used.
The same operation as in Example 4 was repeated. After the polymerization was repeated 20 times, a small amount of deposit was observed on the inner wall of the reaction vessel at the place corresponding to the repeated contact surface. (See FIG. 3) Example 6 85 g of xylene 10 and sorbitan monooleate (HLB = 4.3) as an emulsifier in the reaction vessel used in Example 1.
Was charged to remove dissolved oxygen.

On the other hand, 1500 g of acrylamide is dissolved in 2250 g of ion-exchanged water in another flask to prepare a monomer aqueous solution having a monomer concentration of 40% by weight, and then nitrogen gas is blown in to remove oxygen dissolved in the aqueous solution. did. Next, the aqueous monomer solution in this flask was added to the above reaction vessel, and the mixture was emulsified with stirring to add 2.2 g of benzoyl peroxide as a polymerization initiator as a xylene solution. Then, cooling water of 30 ° C is poured into the jacket for cooling water, and warm water of 55 ° C is flown into the jacket for heating to start the polymerization reaction, and this state is kept for 12 hours to complete the polymerization, and the hydrophilic polymer The emulsion was obtained, and the emulsion was discharged from the reaction vessel to complete one polymerization operation. Thereafter, the same polymerization operation as above was continuously repeated to carry out polymerization 20 times in total. After the completion of 20 times of polymerization, no deposit was found on the inner wall of the reaction vessel at the place corresponding to the repeatedly repeated contact surface.

Comparative Example 4 The same operation as in Example 5 was repeated except that hot water at 65 ° C. was flown through the jacket for cooling water in Example 6.
After the completion of 20 times of polymerization, a large amount of deposits was observed on the inner wall of the reaction vessel at the place corresponding to the repeated repeated contact surface.

The results of Examples 1 to 6 and Comparative Examples 1 to 4 are summarized in Table 1 above.

[Brief description of the drawings]

FIG. 1 is a front view of the reaction container in Example 1. FIG. 2 is a diagram showing a state of attachment of deposits on the inner wall of the reaction vessel after repeating the polymerization reaction 20 times in Comparative Example 1. FIG. 3 is a diagram showing the state of attachment of deposits on the inner wall of the reaction vessel after repeating the polymerization reaction 20 times in Example 5. 1 ... Stirring blade 2 ... Reflux condenser 3 ... Thermometer 4 ... Drip funnel 5 ... Nitrogen gas introduction pipe 6 ... Cooling water jacket 7 ... Heating water jacket 8 ... Gel deposit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C08F 220/58 C08F 220/58 299/02 299/02 Examiner Susumu Sugihara (56) References 59-58001 (JP, A) JP 61-51001 (JP, A)

Claims (14)

(57) [Claims] 1. A reaction vessel equipped with a rotary stirring blade, wherein an aqueous solution of a monomer component is dispersed in a polymerization-inert hydrophobic organic solvent in the presence of a dispersant to carry out reverse phase suspension polymerization or reverse phase emulsion. When a hydrophilic polymer is produced by polymerization, at least an inner wall of the reaction vessel is repeatedly contacted repeatedly with a suspension (emulsion) liquid and a gas, and the surface roughness represented by R _max is adjusted to 3 μm or less. And a method for producing a hydrophilic polymer, characterized in that at least the repeating contact surface is cooled from the back surface with cooling water at a temperature of 60 ° C. or less. 2. The method according to claim 1, wherein the surface of the rotary stirring blade and the inner wall of the reaction vessel are made of stainless steel or stainless casting. 3. The manufacturing method according to claim 1, wherein the surface roughness is adjusted to 0.5 μm or less. 4. The method according to claim 1, wherein the surface roughness is adjusted to 0.1 μm or less. 5. The method according to claim 3, wherein the surface roughness is adjusted by immersion electrolytic polishing. 6. The manufacturing method according to claim 3, wherein the surface roughness is adjusted by electrolytic composite polishing. 7. The production method according to claim 1, wherein the surface roughness is adjusted on the entire inner wall of the reaction vessel. 8. The manufacturing method according to claim 1, wherein the surface roughness is further adjusted on the entire surface of the rotary stirring blade. 9. The monomer component is (meth) acrylic acid, 2-
(Meth) acryloylethanesulfonic acid, 2- (meth)
Acrylamido-2-methylpropanesulfonic acid, salts of these unsaturated acids, N, N-dimethylaminoethyl (meth)
One or more monomers (A) selected from the group consisting of acrylates and quaternary compounds thereof, methoxypolyethylene glycol (meth) acrylate and (meth) acrylamide, and two polymerizable double bonds in the molecule. 9. The crosslinkable monomer (B) having the above, wherein the ratio of the monomer (B) to the monomer (A) is 0.001 to 50 mol%. The manufacturing method according to item. 10. The production method according to claim 1, wherein the concentration of the aqueous solution of the monomer component at the initial stage of polymerization is 10% by weight to a saturated concentration. 11. A cooling water temperature of 50 ° C. or lower.
The manufacturing method according to any one of 1. 12. The manufacturing method according to claim 11, wherein the cooling water temperature is 40 ° C. or lower. 13. The method according to any one of claims 1 to 13, wherein the dispersant is a nonionic surfactant having an HLB of 2 to 14. 14. The dispersant is one or more selected from the group consisting of sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, and polyoxyethylene alkylaryl ether. Manufacturing method.