JP2742447B2 - Dispersant for reversed phase suspension polymerization and method for producing hydrophilic polymer using the dispersant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to reverse phase suspension polymerization by adding a water-soluble ethylenically unsaturated monomer or an aqueous solution thereof to a polymerization-inactive and hydrophobic organic solvent. TECHNICAL FIELD The present invention relates to a dispersant used when performing the method and a method for producing a hydrophilic polymer using the dispersant.
More specifically, a dispersant for reversed-phase suspension polymerization, which provides a spherical polymer particle having a large average particle size, has a very small amount of deposits on the side walls of a polymerization tank during polymerization, and provides a stable polymerization system, and this dispersant. And a method for producing a hydrophilic polymer using the same.

(Prior Art) Method 1 of Polymerizing Water-Soluble Ethylenically Unsaturated Monomer
One known method is a reversed-phase suspension polymerization method in which a water-soluble ethylenically unsaturated monomer or an aqueous solution thereof is suspended and dispersed in a hydrophobic organic solvent for polymerization. In carrying out the reverse phase suspension polymerization method, a dispersant is usually used in order to stabilize the dispersion of the monomer in the organic solvent and to prevent or reduce the aggregation and unification of the produced polymer particles. In addition, since the particle size of the obtained polymer particles and the stability of the system largely depend on the dispersant, the selection of the dispersant is important.

Conventionally, as a dispersing agent used for the reverse phase suspension polymerization of a water-soluble ethylenically unsaturated monomer, for example, nonionic surfactants such as sorbitan fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, and sucrose fatty acid ester Surfactants, cellulose derivatives such as cellulose ethers and cellulose esters have been known (Japanese Patent Publication No.
-30710, JP-A-57-158209, etc.).

(Problems to be Solved by the Invention) However, when the above-mentioned nonionic surfactant is used, the average particle size of the obtained polymer is 100 μm or less,
In addition, the particle size distribution became considerably wide, and when the polymer was handled as powder, dust measures were required. In addition, there is a problem that the amount of adhesion to the wall surface of the reaction vessel during polymerization is large.

On the other hand, when a cellulose derivative such as cellulose ether or cellulose ester is used, the average particle size of the polymer is 10%.
Although it is as large as about 0 to 200 μm, the solubility of these dispersants in a hydrophobic organic solvent is generally low, and the dispersant easily precipitates at room temperature and a mass of the dispersant is mixed in the product,
Further, there is a disadvantage that the mass of the dispersing agent is melted during drying of the product to fuse the product.

Further, when the organic solvent is refluxed during the polymerization or when the organic solvent or the mixture of the organic solvent and water is removed by distillation after the polymerization, there is a problem that the dispersing action is reduced at a high temperature and the temperature is restricted. .

The inventors of the present invention have repeatedly studied focusing on dispersants in order to solve the above problems, and as a result, have reached the present invention.

Accordingly, an object of the present invention is to provide a dispersant for reversed-phase suspension polymerization that provides a polymer particle having a large average particle size and has extremely small amount of deposits on a side wall of a polymerization tank during polymerization, and provides a stable polymerization system. To provide.

Another object of the present invention is to provide a method for producing a hydrophilic polymer which is easy to handle as a powder without the problem of dust with high yield by reverse phase suspension polymerization.

(Means for Solving the Problems) The present inventors have conducted intensive studies to achieve the above object, and as a result, have reached the present invention.

That is, the present invention relates to a dispersion for reverse phase suspension polymerization used when performing a reverse phase suspension polymerization by adding a water-soluble ethylenically unsaturated monomer or an aqueous solution thereof to a polymerization inert and hydrophobic organic solvent. (A) general formula (I): (Wherein, R ¹ is hydrogen or a methyl group, and X is an alkylene oxide residue having 2 to 4 carbon atoms comprising 50% by weight or more of ethylene oxide residues based on the total weight of all alkylene oxide residues. And n is an integer from 3 to 300;
² is hydrogen, an alkyl group having 1 to 3 carbon atoms or 2 to 2 carbon atoms.
And at least one structural unit (A) represented by general formula (II): (Wherein, R ³ is hydrogen or a methyl group, and R ⁴ has ⁴ carbon atoms.
60, the alkyl group, an alkenyl group, an aryl group, an aralkyl group, a cyclic alkyl, cyclic alkenyl group, or a -COOR ⁵ (where,, R ⁵ is of 4 to 60 carbon atoms, an alkyl group,
An alkenyl group, an aryl group, an aralkyl group, a cyclic alkyl group or a cyclic alkenyl group)), and the content of the structural unit (A) is from 5 to 65. % By weight, the content of the structural unit (B) is 35 to 95% by weight, the total content of the structural unit (A) and the structural unit (B) is 70% by weight or more, and the average molecular weight is
A polymer surfactant comprising a polymer (C) in the range of 1,000 to 500,000; and (b) a low molecular ionic surfactant having a hydrophobic group having 8 to 30 carbon atoms and an ionic group. And a dispersant for reversed-phase suspension polymerization.

The present invention also provides a hydrophilic polymer obtained by dispersing a water-soluble ethylenically unsaturated monomer or an aqueous solution thereof in a polymerization-inactive hydrophobic organic solvent and subjecting it to reverse phase suspension polymerization with a water-soluble radical polymerization initiator. When producing the above, the dispersant for reverse phase suspension polymerization is used as a dispersant in an amount of 0.2 to 5 per 100 parts by weight of the unsaturated monomer.
The present invention relates to a method for producing a hydrophilic polymer, which is used in a ratio of parts by weight.

 Hereinafter, the present invention will be described in detail.

In the general formula (I) representing the hydrophilic structural unit (A) constituting the polymer (C) in the present invention,-(X) _n -is an n-alkylene oxide residue having 2 to 4 carbon atoms, that is, polyoxy. An alkylene group is shown, and 50% by weight or more of all alkylene oxide residues are ethylene oxide residues. N indicating the total number of moles of alkylene oxide added is 3
It is an integer of 300300, preferably 3-100. R ² is a terminal group of a polyoxyalkylene chain, and is a hydrogen atom, an alkyl group (eg, methyl group, ethyl group, n-propyl group, isopropyl group), or an alkenyl group (eg, vinyl group, methylvinyl group, allyl group). It is.

R ⁴ in the general formula (II) representing the hydrophobic structural unit (B) is an alkyl group having 4 to 60 carbon atoms, an aryl group, —CO
Although organic group represented by OR ^5, Specific examples of groups other than the group represented by -COOR ^5, n- butyl, n- hexyl, 2-ethylhexyl group, n- octyl group, n-
Nonyl group, 1,3,5-trimethylhexyl group, decyl group,
Alkyl groups such as dodecyl group and octadecyl group; alkenyl groups such as butenyl group, decenyl group and oleyl group; aryl groups such as phenyl group, methylphenyl group, octylphenyl group, nonylphenyl group and naphthyl group; benzyl group and methylbenzyl Groups, aralkyl groups such as phenethyl group; cyclic alkyl groups such as cyclohexyl group and dimethylcyclohexyl group; cyclic alkenyl groups such as cyclopentenyl group. As the R ⁵ in the group represented by -COOR ⁵ in R ^4, R ⁴ above
And the same groups as the groups other than -COOR ^{5 in the} above.

It is desirable that the polymer (C) as a high molecular surfactant constituting the dispersant for reversed phase suspension polymerization of the present invention has a moderately hydrophilic property and is dissolved in a hydrophobic organic solvent. Therefore, regarding the content of each structural unit constituting the polymer (C), the structural unit (A) is 5 to 65% by weight, preferably 10% by weight.
-40% by weight, structural unit (B) in the range of 35-95% by weight, preferably 60-90% by weight, and structural unit (A) and structural unit (B) in polymer (C). Is in the range of 70% by weight or more. Polymers outside these ranges have too high a hydrophobic or hydrophilic property, and the polyoxyalkylene chain and the hydrophobic chain cannot be balanced. Therefore, when reverse phase suspension polymerization is performed using such a polymer, problems such as generation of a large amount of aggregates during polymerization and generation of a large amount of deposits on the side wall of the polymerization tank occur.

The molecular weight of the polymer (C) is desirably 1,000 to 500,000, preferably 3,000 to 300,000.

The method for obtaining the polymer (C) is not particularly limited, and it can be produced by any method. For example, (1) a vinyl monomer which forms a structural unit (A) represented by the general formula (I) by polymerization and a vinyl monomer which forms a structural unit (B) represented by the general formula (II) A method of copolymerizing a monomer with another monomer, if necessary, (2)
Esterification of a raw material polymer that produces a polymer (C) containing a structural unit (A) and a structural unit (B) by modification such as an esterification reaction with an alcohol, with an alcohol or an alkyl halide, etc. Reaction, an addition reaction of an alkylene oxide, or a method of modifying a polyoxyalkylene chain by a terminal modification reaction.

In the method (1), examples of the vinyl monomer that produces the hydrophilic structural unit (A) include a polyalkylene glycol derivative or a vinyl ester of an alkylene oxide adduct as shown below. Also contains at least 50% by weight of ethylene oxide units with respect to the total weight of the polyoxyalkylene chain, and these terminal alcoholates are monomers alkoxylated with an alkyl group having 1 to 3 carbon atoms, and the terminal alkenoxylates Is a monomer alkenylated with an alkenyl group having 2 to 5 carbon atoms.

Specific examples of the vinyl monomer that forms the structural unit (A) include, for example, polyalkylene glycol mono (meth) acrylates such as polyethylene glycol mono (meth) acrylate and polyethylene glycol-polypropylene glycol mono (meth) acrylate; Glycol (meth) acrylate, methoxy polyethylene glycol-polypropylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol-polypropylene glycol (meth) acrylate, etc., alkoxylated with an alkyl group having 1 to 3 carbon atoms. Alkoxypolyalkylene glycol (meth) acrylate; carbon number 2 such as aryloxy polyethylene glycol (meth) acrylate Such as 5 alkenoxy reduction has been alkenoxy polyalkylene glycol (meth) acrylate with an alkenyl group can be exemplified, of 1
Species or two or more can be used.

In the method (1), the hydrophobic structural unit (B)
Examples of the vinyl monomer for producing the compound include aliphatic vinyl compounds such as 1-hexene, 1-octene, isooctene, 1-nonene, 1-decene, 1-dodecene, and vinylcyclohexane; styrene, α-methylstyrene, p −
Aromatic vinyl compounds such as methylstyrene, 3-phenyl-1-propene and vinylnaphthalene; butyl (meth)
Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate,
Phenyl (meth) acrylate, naphthyl (meth) acrylate, p-methylphenyl (meth) acrylate,
Octylphenyl (meth) acrylate, nonylphenyl (meth) acrylate, dinonylphenyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, etc., as well as alkyl, alkenyl, and aryl groups having 4 to 60 carbon atoms Group, an aralkyl group, a cyclic alkyl group, and a (meth) acrylate having a cyclic alkenyl group.
Species or two or more can be used.

As described above, the ratio of the monomer that can be used in the case of producing the polymer (C) by the method (1) is such that the content in the polymer (C) after polymerization is the structural unit ( A) is 5
~ 65% by weight, preferably 10-40% by weight, structural unit (B)
Is 35 to 95% by weight, preferably 60 to 90% by weight, and the total content of the structural units (A) and (B) is 70% by weight or more.

Therefore, a monomer that forms a structural unit other than the structural unit (A) and the structural unit (B) after polymerization is in a range that does not impair the effects of the present invention, that is, contained in the polymer (C). Used within the range of 30% by weight or less,
Monomer which forms structural unit (A) and structural unit (B)
Can be copolymerized with a monomer that produces Examples of monomers that generate such structural units other than the structural units (A) and (B) include (meth) acrylic acid (salt), maleic acid (salt), fumaric acid (salt), Various unsaturated carboxylic acids (salts) such as crotonic acid (salt) and itaconic acid (salt); (meth) allyl sulfonic acid (salt); sulfoethyl (meth) acrylate (salt), styrene sulfonic acid (salt), vinyl sulfone Various sulfonic acids (salts) such as acid (salt) and 2-acrylamido-2-methylpropanesulfonic acid (salt); various types such as (meth) acrylamide, N-methylol (meth) acrylamide and dimethylaminoethyl (meth) acrylamide (Meth) acrylamide; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl ( Various aminoalkyl (meth) acrylate or a quaternary compound such as data) acrylate; methyl (meth) acrylate, ethyl (meth) acrylate,
1 to 3 carbon atoms such as n-propyl (meth) acrylate
An alkyl (meth) acrylate having an alkyl group of
A vinyl compound having an organic group having 3 or less carbon atoms such as ethylene, propylene, or isobutene as a substituent; acrylonitrile, vinyl chloride, glycidyl (meth) acrylate, or the like; one or more of these may be used; be able to.

In order to produce the polymer (C) by the method (1), the monomer component may be copolymerized by a known method using a polymerization initiator. The copolymerization can be carried out by a method such as polymerization in a solvent or bulk polymerization.

The polymerization in the solvent can be carried out batchwise or continuously, and examples of the solvent used include water; lower alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol; benzene, toluene, xylene, cyclohexane, Aromatic, aliphatic or heterocyclic compounds such as n-hexane and dioxane; ketone compounds such as ethyl acetate, acetone and methyl ethyl ketone; Examples of the polymerization initiator include persulfates such as ammonium persulfate and sodium persulfate, peroxides such as benzoyl peroxide and lauroyl peroxide, hydroperoxides such as cumene hydroperoxide, and aliphatics such as azobisisobutyronitrile. An azo compound or the like is used. In this case, an accelerator such as an amine compound may be used in combination. The polymerization temperature is
It is appropriately determined depending on the solvent and the polymerization initiator used,
Usually, it is carried out within a range of 0 to 150 ° C.

In the bulk polymerization, peroxides such as benzoyl peroxide and lauroyl peroxide, hydroperoxides such as cumene hydroperoxide as polymerization initiators,
Using an aliphatic azo compound such as azobisisobutyronitrile and azobisdimethylvaleronitrile, 50 to 150
It is performed within a temperature range of ° C.

In addition, the copolymer obtained by copolymerization in this manner can be used as a polymeric surfactant as it is, but if necessary, the solvent used in the polymerization can be separated and removed or other solvents and the like can be used. It can be used in place of water or the like.
Alternatively, a basic substance such as a hydroxide or oxide of an alkali metal or alkaline earth metal, a carbonate, ammonia, or an organic amine may be added as a pH adjuster before use.

Next, when producing the polymer (C) by the method (2), the raw material polymer to be subjected to the modification and the modification method are as follows: (a) a (meth) acrylic acid-based polymer as a raw material;
A method by an esterification reaction with an alcohol which forms the structural unit (A) after the modification and an alcohol or an alkyl halide which forms the structural unit (B), (b) a (meth) acrylic acid system having the structural unit (B) A method in which an esterification reaction with an alcohol to form a structural unit (A) is performed using a copolymer as a raw material, and (c) a structure obtained by adding an alkylene oxide to a (meth) acrylic acid-based polymer having a structural unit (B). A method of introducing a unit (A), (d) a method of subjecting a (meth) acrylic acid ester-based polymer as a raw material to a transesterification reaction with an alcohol which forms a structural unit (A) and a structural unit (B) after modification. (E) (1)
And the polymer obtained by the method (a) to (c) of (2), wherein the terminal group of the polyoxyalkylene chain is an —OH group, and the terminal —OH group is used as the starting polymer. Examples of the method include denaturation by a method such as etherification, (meth) acryloylation, or dimethylacryloylation.

When the polymer (C) is obtained by each method of (2), the following conditions must be satisfied. That is, the content of the structural unit (A) in the modified polymer (C) is 5 to 65% by weight, preferably 10 to 40% by weight, and the content of the structural unit (B) is 35 to 95% by weight. , Preferably 60 to 90% by weight, and the total content of the structural units (A) and (B) in the polymer (C) must be 70% by weight or more,
When the alkylene oxide is added to introduce the structural unit (A), the content of the ethylene oxide unit in the polyoxyalkylene chain after the addition needs to be 50% by weight or more.

Specific examples of the method (a) include, as a (meth) acrylic acid-based polymer which is a raw material polymer that can be used, poly (meth) acrylic acid or a copolymer of acrylic acid and methacrylic acid. And one or two of these polymers and an alcohol capable of producing a structural unit (A) such as polyethylene glycol, methoxypolyethylene glycol, methoxypolyethylene glycol-polypropylene glycol, ethoxypolyethylene glycol, and allyloxypolyethylene glycol. Above, and butanol, octanol, dodecanol,
Oleyl alcohol, phenol, nonylphenol,
The polymer (C) can be obtained by esterifying one or more alcohols capable of forming the structural unit (B) such as benzyl alcohol by a known method.

As specific examples of the method (b), examples of the raw material polymer include (meth) acrylate having an alkyl group having 4 to 60 carbon atoms, and alkyl having 1 to 40 carbon atoms as a substituent. Phenyl (meth) acrylate, styrene, α-methylstyrene, carbon number 4-60
And copolymers of (meth) acrylic acid with one or two or more kinds of α-olefins having a substituent represented by the following formula (A). A method of esterifying the alcohol producing A) with a known method can be used.

Examples of the raw material polymer that can be used in the method (c) include the same copolymers as those described in the method (b). These copolymers include ethylene oxide and, if necessary, propylene oxide or propylene oxide. The polymer (C) can be obtained by adding an alkylene oxide such as butylene oxide by a known method.

The method (d) uses a lower alkyl ester of poly (meth) acrylic acid such as poly (methyl) methacrylate or poly (meth) ethyl acrylate, or a copolymer of methyl acrylate and methyl methacrylate as a raw material. One or two kinds of alcohols capable of forming a structural unit (A) such as polyethylene glycol, methoxypolyethylene glycol, methoxypolyethylene glycol-polypropylene glycol, ethoxypolyethylene glycol, and allyloxypolyethylene glycol; Using one or more of the above and alcohols capable of forming a structural unit (B) such as butanol, octanol, dodecanol, oleyl alcohol, phenol, nonylphenol, and benzyl alcohol,
The polymer (C) can be obtained by a transesterification reaction according to a known method.

The method (e) is a method in which a polymer having a polyoxyalkylene chain whose terminal group is an —OH group is used as a raw material and the terminal is modified. Examples of the etherification modification include, for example, the raw material polymer and an alkyl group having 1 to 3 carbon atoms such as methyl chloride, methyl bromide, ethyl chloride, propyl chloride, and allyl chloride or an alkenyl group having 2 to 3 carbon atoms. And a method in which a Williamson reaction is performed by a known method using at least one selected from halogenated hydrocarbons. In order to carry out modification such as (meth) acryloylation or (iso) crotonoylation, the raw material polymer and one or more kinds selected from (meth) acrylic acid, (iso) crotonic acid, dimethylacrylic acid and the like are used. The esterification may be performed by a known method.

The hydrophobic group having 8 to 30 carbon atoms constituting the low molecular ionic surfactant (b), which is another component of the dispersant for reversed phase suspension polymerization of the present invention, is not particularly limited, For example, alkyl groups such as octyl group, dodecyl group and heptadecyl group; alkenyl groups such as decenyl group, 8-heptadecenyl group and oleyl group; hydroxyalkyl groups such as 11-hydroxyheptadecyl group and 11-hydroxyundecyl group; octylphenyl And aryl groups such as a nonylphenyl group and a naphthyl group. Examples of such a low molecular ionic surfactant having a hydrophobic group include an anionic surfactant, a cationic surfactant,
Zwitterionic surfactants can be mentioned.

Examples of low molecular anionic surfactants include lauric acid (salt), stearic acid (salt), oleic acid (salt),
Fatty acids (salts) such as ricinoleic acid (salt) and 12-hydroxystearic acid (salt) or modified products thereof; alkyl sulfates (salts) such as lauryl sulfate (salt) and stearyl sulfate (salt); dodecylbenzene sulfone Alkylbenzenesulfonic acid (salt) such as acid (salt); polyoxyethylene dodecyl ether sulfate (salt), polyoxyethylene nonylphenyl ether sulfate (salt), polyoxyethylene-sec-alkyl ether sulfate (salt), etc. Α-olefinsulfonic acid (salt); alkylnaphthalenesulfonic acid (salt); dialkyl sulfosuccinic acid (salt); monoalkyl ester sulfosuccinate (salt); higher alcohol ethoxylate Mo sulfosuccinate No. (salt); alkyl phosphoric acid (salt); sulfated fatty acid ester (salt); petroleum sulfonic acid (salt); and (polyoxyethylene) alkyl ether carboxylic acid (salt). These can be used alone or in combination of two or more.

Each of these low molecular weight anionic surfactants is an acid having a hydrophobic group or a salt thereof, but the kind of the salt is not particularly limited. For example, alkali metal salts such as sodium salt and potassium salt; magnesium salt , Calcium salts and other alkaline earth metal salts; ammonium salts; alkylamine salts such as methylamine salts, dimethylamine salts, trimethylamine salts, ethylamine salts, diethylamine salts, triethylamine salts; monoethanolamine salts, diethanolamine salts, triethanolamine Alkanolamine salts such as salts; and pyridinium salts.

Examples of low molecular weight cationic surfactants include primary amines (salts) such as laurylamine (salt), stearylamine (salt) and benzylamine (salt); dilaurylamine (salt), distearylamine ( Tertiary amines (salts) such as lauryl dimethylamine (salt) and stearyl dimethylamine (salt); lauryl trimethyl ammonium (salt), stearyl trimethyl ammonium (salt), diamine Quaternary ammonium (salt) such as stearyldimethylammonium (salt), laurylbenzyldimethylammonium (salt), cetylpyridinium (salt); (di) hydroxyethylalkylamine (salt); polyoxyethylene alkylamine (salt) Is mentioned.

These low molecular weight cationic surfactants are amine compounds or salts thereof, or quaternary ammonium salts. The type of the salt is not particularly limited. For example, the salts of amine compounds include acetate, Formate, hydrochloride, hydrogen bromide and the like, and quaternary ammonium salts include quaternary ammonium chloride and quaternary ammonium bromide.

Examples of low-molecular zwitterionic surfactants include amino acid-type zwitterionic surfactants such as laurylaminopropionic acid (salt), stearylaminopropionic acid (salt), and nitrilolaurildiacetic acid (salt); lauryl dimethyl betaine, stearyl dimethyl Betaine types such as betaine, lauryl dihydroxyethyl betaine, 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, 2-heptadecyl-N-sodiumcarboxymethyl-N-carboxymethyloxyethylimidazolinium betaine Zwitterionic surfactants; phosphate (salt) type zwitterionic surfactants such as lecithin; sulfonic acid (salt) zwitterionic surfactants; and the like.

In the dispersant for reverse phase suspension polymerization of the present invention, the proportions of the high molecular surfactant (a) and the low molecular ionic surfactant (b) are 50 to 99% by weight and 1 to 50% by weight, respectively. , Preferably 70-99% by weight and 1-30% by weight.

The water-soluble ethylenically unsaturated monomer that can be subjected to reverse-phase suspension polymerization using the dispersant for reverse-phase suspension polymerization of the present invention has a certain solubility in water, and the polymer is hydrophilic. There is no particular limitation as long as it has a property. For example, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, 2-
(Meth) acryloylethanesulfonic acid, 2- (meth)
Anionic monomers such as acryloylpropanesulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid and styrenesulfonic acid and salts thereof; (meth) acrylamide, N-substituted (meth) acrylamide, Nonionic monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; dimethylaminoethyl (meth)
Cationic monomers such as acrylate, diethylaminopropyl (meth) acrylate, and dimethylaminopropyl (meth) acrylamide and quaternized products thereof; vinyl imidazole, vinyl pyridine, vinyl pyrrolidone, and the like. Among such water-soluble ethylenically unsaturated monomers, (meth) acrylic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid and salts thereof, dimethyl One or more selected from the group consisting of aminoethyl (meth) acrylate and its quaternary product, and (meth) acrylamide are preferably used. As long as the water solubility of these water-soluble ethylenically unsaturated monomers is not impaired, hydrophobic unsaturated monomers such as alkyl (meth) acrylate, vinyl acetate, and styrene are mixed to form a reverse phase. It may be subjected to suspension polymerization.

When the water solubility of the water-soluble ethylenically unsaturated monomer is used in the present invention, the monomer concentration in the monomer aqueous solution can be arbitrarily selected over a wide range, but is preferably 20% by weight or more to a saturated concentration. .

When preparing the monomer aqueous solution, a predetermined thickener may be mixed to adjust the viscosity of the monomer aqueous solution. Examples of the thickening agent used at that time include hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose, polyethylene glycol, polyethylene oxide, polyacrylamide, polyvinyl alcohol, polyacrylic acid, polyacrylic acid (partially) neutralized product, Examples include crosslinked polyacrylic acid, crosslinked polyacrylic acid (partially) neutralized product, dextrin, and sodium alginate. The viscosity of the aqueous monomer solution at that time was measured using a Brookfield rotational viscometer (25 ° C., 60 rpm), and was 15 to 5,000 cps, especially 2
A range from 0 to 3,000 cps is preferred. By increasing the viscosity of the aqueous monomer solution in this manner, an effect is obtained in which the average particle size of the polymer obtained by polymerization becomes larger than when the polymer is not used.

As the hydrophobic organic solvent that can be used in the reverse phase suspension polymerization in the present invention, those commonly used for reverse phase suspension polymerization are used, for example, n-pentane, n-hexane, n-heptane, n-octane. Aliphatic hydrocarbons which may have a substituent such as cyclohexane, cyclooctane, methylcyclohexane and decalin; and those having a substituent such as benzene, ethylbenzene, toluene and xylene And aromatic hydrocarbons, and one or a mixture of two or more thereof can be used. Among these, n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene and xylene are particularly preferred.

The ratio of the hydrophobic organic solvent to the water-soluble ethylenically unsaturated monomer or an aqueous solution thereof is generally 1: 1 to 4: 1 from the viewpoint of removing the heat of polymerization, controlling the temperature during the polymerization, or stably dispersing.
Is appropriate.

The polymerization conditions for the reverse phase suspension polymerization using the dispersant for reversed phase suspension polymerization of the present invention may be the usual conditions employed in conventional reverse phase suspension polymerization. For example, the polymerization temperature can be appropriately selected usually in the range of 20 to 100 ° C. depending on the type of the water-soluble ethylenically unsaturated monomer and the type of the polymerization initiator to be used.

Further, as the water-soluble radical polymerization initiator for reverse phase suspension polymerization, any one can be used without limitation as long as it is commonly used in the art, for example, potassium persulfate,
Persulfates such as sodium persulfate and ammonium persulfate; hydroperoxides such as hydrogen peroxide, t-butyl hydroperoxide and cumene hydroperoxide; azo such as 2,2'-azobis-2-amidinopropane dihydrochloride And the like. In general, the amount of the water-soluble radical polymerization initiator used is preferably in the range of 0.001 to 5 mol% based on the water-soluble ethylenically unsaturated monomer.

In the present invention, the desired hydrophilic polymer can be produced by subjecting the water-soluble ethylenically unsaturated monomer to reverse phase suspension polymerization using the dispersant for reverse phase suspension polymerization.

The amount of the dispersant for reverse-phase suspension polymerization used in the reverse-phase suspension polymerization is determined based on the amount of the water-soluble ethylenically unsaturated monomer 10 used for the polymerization.
It is in the range of 0.2 to 5 parts by weight, preferably 1 to 4 parts by weight based on 0 parts by weight. If the dispersant is used in a small amount of less than 0.2 parts by weight, agglomerates are formed during reverse phase suspension polymerization, and deposits are easily generated on the side walls of the polymerization tank. Further, even if the amount of the dispersant used exceeds 5 parts by weight, not only is it uneconomical, but also the particle size distribution of the finally obtained hydrophilic polymer becomes wide. Further, as long as the effects of the present invention are not impaired, a conventionally known dispersant for reversed phase suspension polymerization may be used in combination.

The polymerization method may be in accordance with a conventional reversed-phase suspension polymerization method.For example, a water-soluble ethylenically unsaturated monomer containing a water-soluble radical polymerization initiator or an aqueous solution thereof in a hydrophobic organic solvent containing a dispersant is used. The monomer may be dispersed and suspended under stirring, and the monomer may be polymerized at a predetermined temperature. Dispersant or polymerization initiator or the monomer may be added to the polymerization system at once,
Alternatively, they may be added in portions.

By performing the reverse-phase suspension polymerization in this manner, a suspension in which the hydrophilic polymer or its hydrate is dispersed in a hydrophobic organic solvent is obtained, but the hydrophilic polymer or its hydrate is separated from the organic solvent. Then, if necessary, drying is performed to prepare the desired spherical hydrophilic polymer.

The type and use of the polymer surfactant (a) and the low molecular ionic surfactant (b) of the polymer (C) used as a dispersant during reverse phase suspension polymerization were obtained. The average particle size is generally 100 to 600 μm, preferably 200 to 400 μm, although the amount varies depending on polymerization conditions such as the type of water-soluble ethylenically unsaturated monomer used for polymerization and the monomer concentration during polymerization. Easy to handle powder with narrow diameter distribution.

The hydrophilic polymer obtained in the present invention is, for example, a water-soluble polymer, a hygroscopic polymer, or a water-absorbing polymer, and is not particularly limited as long as it is a polymer having an affinity for water.

A typical example of the water-soluble polymer includes a polymer flocculant, which is a water-soluble ethylenically unsaturated monomer such as (meth) acrylic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acrylamide-
2-methylpropanesulfonic acid and a salt thereof, dimethylaminoethyl (meth) acrylate and a quaternary compound thereof, and (meth) acrylamide can be obtained by using one or more kinds selected from the group consisting of:
Cationic flocculant, anionic flocculant, nonionic flocculant, depending on the type of water-soluble ethylenically unsaturated monomer used,
All types of flocculants such as zwitterionic flocculants can be obtained. This water-soluble polymer has a function of coagulating and dewatering sludge.

The water-absorbing polymer has a function of absorbing water and swelling when the water-soluble polymer cross-links and comes into contact with water, and such a water-absorbing polymer is a self-crosslinking type. However, a copolymer obtained by copolymerizing a small amount of a crosslinking agent having two or more polymerizable unsaturated groups or reactive functional groups during polymerization may be used. As a cross-linking agent used when obtaining a water-absorbing polymer, for example,
N, N'-methylenebis (meth) acrylamide, N-methylol (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, glycerin di (Meth) acrylate, (meth) acrylic acid polyvalent metal salt, trimethylolpropane tri (meth) acrylate, triallyl cyanurate, triallylamine, triallyl phosphate,
Examples thereof include glycidyl (meth) acrylate, ethylene glycol diglycidyl ether, glycerin tri (di) glycidyl ether, and polyethylene glycol diglycidyl ether. These crosslinking agents can be used alone or in combination of two or more.

These cross-linking agents are generally mixed with the water-soluble ethylenically unsaturated monomer at a ratio of about 0.001 to 1.0 mol%, or mixed with the monomer during suspension polymerization or after suspension polymerization. And may be added to the resulting hydrophilic polymer.

(Effect of the Invention) The hydrophilic polymer obtained by using the dispersant for reversed-phase suspension polymerization of the present invention has a large average particle size, a narrow particle size distribution, and spherical particles having good handleability. It is.

Further, according to the present invention, the adhesion of polymer particles to the side wall of the polymerization tank or a stirrer, etc., which has been conventionally observed during reverse phase suspension polymerization of the water-soluble ethylenically unsaturated monomer, is extremely small,
Therefore, continuous production of the hydrophilic polymer becomes possible, and furthermore, polymerization or removal of the organic solvent by distillation can be performed at a high temperature, and productivity can be improved.

(Examples) Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Parts and% are based on weight.

Reference Example 1 50 parts of toluene was charged into a flask equipped with a thermometer, a stirrer, two dropping funnels, a gas inlet tube, and a reflux condenser.
Heated to 0 ° C. Then, while maintaining the same temperature under a nitrogen stream, 30 parts of methoxypolyethylene glycol acrylate (containing 23 ethylene oxide units per molecule on average, average molecular weight of 1099) as a monomer to form the structural unit (A) A monomer mixture solution comprising 70 parts of dodecyl acrylate (molecular weight 240) and 50 parts of toluene as a monomer for producing the structural unit (B) is dropped over 120 minutes,
At the same time, a polymerization initiator solution comprising 1.5 parts of azobisisobutyronitrile and 50 parts of toluene was added dropwise from the other dropping funnel over 180 minutes. After the completion of the dropwise addition, the temperature was further maintained at the same temperature for 60 minutes to complete the polymerization. At this time, the polymerization rate of each monomer was 98% for methoxypolyethylene glycol acrylate as a result of GPC analysis, and 98% for dodecyl acrylate as a result of gas chromatographic analysis. GP)
The average molecular weight of the obtained polymer was 25,000 as a result of GPC analysis using polystyrene as a standard. Similarly, the average molecular weight of the obtained polymer was determined by GPC analysis.) afterwards,
The solvent was distilled off under reduced pressure to obtain a polymer (1).

Reference Example 2 Isopropyl alcohol 50 was placed in the same reactor as in Reference Example 1.
The flask was charged with nitrogen, the atmosphere in the flask was replaced with nitrogen under stirring, and the flask was heated to 80 ° C. under a nitrogen stream. Then, while maintaining the same temperature under a nitrogen stream, 10 parts of polyethylene glycol monoacrylate (containing 5 ethylene oxide units on average per molecule, average molecular weight of 292) as a monomer for forming the structural unit (A). And 30 parts of methoxypolyethylene glycol acrylate (containing an average of 10 ethylene oxide units per molecule, average molecular weight of 526), 60 parts of 2-ethylhexyl methacrylate (molecular weight of 198) as a monomer for forming the structural unit (B), and A monomer mixture solution consisting of 50 parts of isopropyl alcohol was added dropwise over 120 minutes, and simultaneously from the other dropping funnel 1.0 parts of azobisdimethyl valeronitrile and 5 parts of isopropyl alcohol 5
A polymerization initiator solution consisting of 0 parts was added dropwise over 180 minutes. After the completion of the dropwise addition, the temperature was further maintained at the same temperature for 60 minutes to complete the polymerization. At this time, the polymerization rate of each monomer was 97% for polyethylene glycol monoacrylate, 98% for methoxypolyethylene glycol acrylate, and 99% for 2-ethylhexyl methacrylate. The average molecular weight of the obtained polymer was 90000. there were. Thereafter, the solvent was distilled off under reduced pressure to obtain a polymer (2).

Reference Example 3 The same reactor as in Reference Example 1 was charged with 50 parts of benzene, the atmosphere in the flask was replaced with nitrogen under stirring, and the flask was heated to 80 ° C. in a nitrogen stream. Then, while maintaining the same temperature under a nitrogen stream,
Ethoxypolyethylene glycol methacrylate (30 on average per molecule) as a monomer to form the structural unit (A)
Containing 1 ethylene oxide unit, average molecular weight 143
6) A monomer mixture solution comprising 50 parts, 50 parts of stearyl methacrylate (molecular weight 338) as a monomer for producing the structural unit (B) and 50 parts of benzene was dropped over 120 minutes,
At the same time, a polymerization initiator solution consisting of 1.0 part of azobisisobutyronitrile and 50 parts of benzene was added dropwise from the other dropping funnel over 180 minutes. After the completion of the dropwise addition, the temperature was further maintained at the same temperature for 60 minutes to complete the polymerization. At this time, the polymerization rate of each monomer was 97% for ethoxy polyethylene glycol methacrylate and 99% for stearyl methacrylate, and the average molecular weight of the obtained polymer was 110,000. Thereafter, the solvent was distilled off under reduced pressure to obtain a polymer (3).

Reference Example 4 The same reactor as in Reference Example 1 was charged with 50 parts of toluene, the atmosphere in the flask was replaced with nitrogen under stirring, and the flask was heated to 80 ° C. in a nitrogen stream. Then, while maintaining the same temperature under a nitrogen stream,
Methoxy polyethylene glycol methacrylate (an average of 9 per molecule) is used as a monomer for forming the structural unit (A).
Containing 3 ethylene oxide units, average molecular weight 49
6) A monomer mixture solution comprising 10 parts, 90 parts of styrene (molecular weight 104) and 50 parts of toluene as monomers for forming the structural unit (B) is dropped over 120 minutes, and simultaneously from the other dropping funnel. , Azobisdimethylvaleronitrile 1.0
And a polymerization initiator solution composed of 50 parts of toluene and dropwise added over 180 minutes. After the completion of the dropwise addition, the temperature was further maintained at the same temperature for 60 minutes to complete the polymerization. At this time, the polymerization rate of each monomer is ethoxy polyethylene glycol methacrylate.
98% and styrene were 99%, and the average molecular weight of the obtained polymer was 70,000. Thereafter, the solvent was distilled off under reduced pressure to obtain a polymer (4).

Reference Example 5 The same reactor as in Reference Example 1 was charged with 50 parts of toluene, the atmosphere in the flask was replaced with nitrogen under stirring, and the flask was heated to 80 ° C. in a nitrogen stream. Then, while maintaining the same temperature under a nitrogen stream,
Methoxy polyethylene glycol methacrylate (an average of 15 per molecule) is used as a monomer to form the structural unit (A).
Containing ethylene oxide units, average molecular weight 76
1) A monomer mixture solution consisting of 20 parts, 70 parts of styrene (molecular weight 104), 10 parts of 1-decene (molecular weight 140) and 50 parts of toluene as monomers for forming the structural unit (B) is taken over 120 minutes. At the same time, a polymerization initiator solution consisting of 0.5 parts of azobisisobutyronitrile and 50 parts of toluene was added dropwise from the other dropping funnel over 180 minutes. After the completion of the dropwise addition, the temperature was further maintained at the same temperature for 60 minutes to complete the polymerization.
At this time, the polymerization rate of each monomer was 97% for methoxypolyethylene glycol methacrylate, 99% for styrene, 1-
The decene is 95% and the average molecular weight of the obtained polymer is 20
It was 10,000. Thereafter, the solvent was distilled off under reduced pressure to obtain a polymer (5).

Reference Example 6 A flask equipped with a thermometer, a stirrer, two dropping funnels, a gas inlet tube and a reflux condenser was charged with 50 parts of toluene, the inside of the flask was replaced with nitrogen under stirring, and 10 parts of nitrogen was blown under a nitrogen stream.
Heated to 0 ° C. Thereafter, while maintaining the same temperature under a nitrogen stream, n-propoxy polyethylene glycol acrylate (containing 12 ethylene oxide units on average per molecule, average molecular weight 643) as a monomer for forming the structural unit (A) A monomer mixture solution consisting of 15 parts, 85 parts of nonylphenyl acrylate (molecular weight: 274) as a monomer to form the structural unit (B) and 50 parts of toluene was added dropwise over 120 minutes, and simultaneously from the other dropping funnel. A polymerization initiator solution consisting of 1.5 parts of azobisisobutyronitrile and 50 parts of toluene was added dropwise over 180 minutes. After the completion of the dropwise addition, the temperature was further maintained at the same temperature for 60 minutes to complete the polymerization. At this time, the polymerization rate of each monomer was 98% for n-propoxy polyethylene glycol acrylate and 98% for nonylphenyl acrylate, and the average molecular weight of the obtained polymer was 3.8%.
It was 10,000. Thereafter, the solvent was distilled off under reduced pressure to obtain a polymer (6).

Example 1 Cyclohexane 1 was charged into a two-necked separable flask equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen gas inlet tube and a dropping funnel, and the polymer (1) obtained in Reference Example 1 was added thereto. 2.4 g and polyoxyethylene (n =
3) After adding and dissolving 0.6 g of sodium n-dodecyl ether sulfate, dissolved oxygen was expelled by blowing nitrogen gas.

125 g of acrylamide in another flask
It was dissolved in 187.5 g to prepare a monomer aqueous solution having a monomer concentration of 40%. After adding and dissolving 0.2 g of 2,2'-azobis-2-amidinopropane hydrochloride to the aqueous monomer solution, nitrogen gas was blown out to expel oxygen dissolved in the aqueous solution.

Next, the aqueous monomer solution in this flask was added to the separable flask, and dispersed by stirring at 230 rpm. Thereafter, the bath temperature was raised to 60 ° C. to start the polymerization reaction, and then maintained at this temperature for 2 hours to complete the polymerization. Thereafter, the polymer was separated from the solvent by suction filtration, and 85
The polymer was dried under reduced pressure at ℃ to obtain a granular polymer.

The average particle size of the obtained polymer was 280 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization was completed was 0.
It was 18 g.

Example 2 n-Heptane 1 was charged into the same reaction vessel as in Example 1, and 2.25 g of the polymer (2) obtained in Reference Example 2 and 0.75 g of stearyldimethylbetaine were added and dissolved therein. Dissolved oxygen was expelled by blowing gas.

In another flask, 87.9 g of dimethylaminoethyl methacrylate and 37.7 g of acrylic acid were dissolved in 188.4 g of ion-exchanged water to prepare a monomer aqueous solution having a monomer concentration of 40%. After adding and dissolving 0.42 g of 2,2'-azobis-2-amidinopropane hydrochloride to the aqueous monomer solution, nitrogen gas was blown out to expel oxygen dissolved in the aqueous solution.

Next, the aqueous monomer solution in this flask was added to the separable flask, and dispersed by stirring at 230 rpm. Thereafter, the bath temperature was raised to 60 ° C. to start the polymerization, and then maintained at this temperature for 2 hours to complete the polymerization.
Thereafter, the polymer was separated from the solvent by suction filtration, and dried at 85 ° C. under reduced pressure to obtain a granular polymer.

The average particle size of the obtained polymer was 250 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization was completed was 0.
It was 15 g.

Example 3 Cyclohexane 1.0 was charged into the same reaction vessel as in Example 1, and 2.7 g of the polymer (3) obtained in Reference Example 3 and 0.3 g of potassium stearate were added and dissolved.
Dissolved oxygen was expelled by blowing nitrogen gas.

Dimethylaminoethyl acrylate in another flask
125 g was dissolved in 187.5 g of ion-exchanged water to prepare a monomer aqueous solution having a monomer concentration of 40%. 2,2'-
After adding and dissolving 0.2 g of azobis-2-amidinopropane hydrochloride, nitrogen gas was blown out to expel oxygen dissolved in the aqueous solution.

Next, the aqueous monomer solution in this flask was added to the separable flask, and dispersed by stirring at 230 rpm. Thereafter, the bath temperature was raised to 60 ° C. to start the polymerization reaction, and then maintained at this temperature for 2 hours to complete the polymerization. Thereafter, the polymer was separated from the solvent by suction filtration, and 85
The polymer was dried under reduced pressure at ℃ to obtain a granular polymer.

The average particle size of the obtained polymer was 220 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization was completed was 0.
It was 10 g.

Example 4 Cyclohexane 1.0 was charged into the same reaction vessel as in Example 1, and 2.55 g of the polymer (4) obtained in Reference Example 4 was added thereto.
And 0.45 g of sodium lauryl sulfate were added and dissolved, and then nitrogen gas was blown in to expel dissolved oxygen.

In another flask, 37.5 g of acrylamide and 87.5 g of dimethylaminoethyl methacrylate were added to ion-exchanged water 18
It was dissolved in 7.5 g to prepare a monomer aqueous solution having a monomer concentration of 40%. After adding and dissolving 0.42 g of 2,2'-azobis-2-amidinopropane hydrochloride to the aqueous monomer solution, nitrogen gas was blown out to expel oxygen dissolved in the aqueous solution.

Next, the aqueous monomer solution in this flask was added to the separable flask, and dispersed by stirring at 230 rpm. Thereafter, the bath temperature was raised to 60 ° C. to start the polymerization reaction, and then maintained at this temperature for 2 hours to complete the polymerization. Thereafter, the polymer was separated from the solvent by suction filtration, and 85
The polymer was dried under reduced pressure at ℃ to obtain a granular polymer.

The average particle size of the obtained polymer was 290 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization was completed was 0.
It was 20 g.

Example 5 Cyclohexane 1.0 was charged into the same reaction vessel as in Example 1, and 2.49 g of the polymer (5) obtained in Reference Example 5 was added thereto.
After adding and dissolving 0.51 g of n-dodecylamine hydrochloride, dissolved oxygen was expelled by blowing nitrogen gas.

In another flask, 84.6 g of sodium acrylate and 21.6 g of acrylic acid were dissolved in 248 g of ion-exchanged water to prepare a monomer aqueous solution having a monomer concentration of 30%. After adding and dissolving 0.15 g of potassium persulfate to the aqueous monomer solution, nitrogen gas was blown out to expel oxygen dissolved in the aqueous solution.

Next, the aqueous monomer solution in this flask was added to the separable flask, and dispersed by stirring at 230 rpm. Thereafter, the bath temperature was raised to 60 ° C. to start the polymerization reaction, and then maintained at this temperature for 2 hours to complete the polymerization. Thereafter, the polymer was separated from the solvent by suction filtration, and 85
The polymer was dried under reduced pressure at ℃ to obtain a granular polymer.

The average particle size of the obtained polymer is 300 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization is completed is 0.
It was 25 g.

Example 6 Cyclohexane 1.0 was charged into the same reaction vessel as in Example 1, and 2.30 g of the polymer (6) obtained in Reference Example 6 was added thereto.
And sodium n-dodecylbenzenesulfonate 0.20
After adding g to dissolve, nitrogen gas was blown in to expel dissolved oxygen.

In another flask, 84.6 g of sodium acrylate, 21.6 g of acrylic acid, and 0.02 g of methylenebisacrylamide were dissolved in 196.6 g of ion-exchanged water to prepare a monomer aqueous solution having a monomer concentration of 35%. Potassium persulfate is added to this aqueous monomer solution.
After adding and dissolving 0.15 g, nitrogen gas was blown in to expel oxygen dissolved in the aqueous solution.

Next, the aqueous monomer solution in this flask was added to the separable flask, and dispersed by stirring at 230 rpm. Thereafter, the bath temperature was raised to 60 ° C. to start the polymerization reaction, and then maintained at this temperature for 2 hours to complete the polymerization. Thereafter, the polymer was separated from the solvent by suction filtration, and 85
The polymer was dried under reduced pressure at ℃ to obtain a granular polymer.

The average particle size of the obtained polymer was 270 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization was completed was 0.
17 g.

Comparative Example 1 Polymerization and drying were carried out in the same manner as in Example 1 except that 3.5 g of sorbitan monostearate was used as a dispersant to obtain a polymer.

The average particle size of the obtained polymer is 90 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization is 2.3 g.
And many.

Comparative Example 2 Polymerization and drying were carried out in the same manner as in Example 1 except that 3.5 g of ethyl cellulose was used as a dispersant to obtain a polymer.

The average particle size of the obtained polymer is 210 μm and the amount of deposits on the stirrer and the separable flask after the polymerization is 4.8 g.
And many.

Comparative Example 3 Polymerization and drying were carried out in the same manner as in Example 5 except that 3.5 g of sorbitan monooleate was used as a dispersant to obtain a polymer.

The average particle size of the obtained polymer is 65 μm, and the amount of deposits in the stirrer and the separable flask after the polymerization is 2.6 g.
And many.

Comparative Example 4 Polymerization and drying were carried out in the same manner as in Example 5 except that 3.5 g of ethyl cellulose was used as a dispersing agent to obtain a polymer.

The average particle size of the obtained polymer was 220 μm, and the amount of deposits on the stirrer and the separable flask after the polymerization was 5.
It was as much as 5g. In addition, ethyl cellulose was found to be mixed in the polymer.

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Claims (5)

(57) [Claims] 1. A dispersant for reversed-phase suspension polymerization, which is used when reverse-phase suspension polymerization is carried out by adding a water-soluble ethylenically unsaturated monomer or an aqueous solution thereof to a polymerization-inert and hydrophobic organic solvent. (A) general formula (I): (Wherein, R ¹ is hydrogen or a methyl group, and X is an alkylene oxide residue having 2 to 4 carbon atoms comprising 50% by weight or more of ethylene oxide residues based on the total weight of all alkylene oxide residues. And n is an integer from 3 to 300;
² is hydrogen, an alkyl group having 1 to 3 carbon atoms or 2 to 2 carbon atoms.
And at least one structural unit (A) represented by general formula (II): (Wherein, R ³ is hydrogen or a methyl group, and R ⁴ has ⁴ carbon atoms.
60, the alkyl group, an alkenyl group, an aryl group, an aralkyl group, a cyclic alkyl, cyclic alkenyl group, or a -COOR ⁵ (where,, R ⁵ is of 4 to 60 carbon atoms, an alkyl group,
An alkenyl group, an aryl group, an aralkyl group, a cyclic alkyl group or a cyclic alkenyl group)), and the content of the structural unit (A) is from 5 to 65. % By weight, the content of the structural unit (B) is 35 to 95% by weight, the total content of the structural unit (A) and the structural unit (B) is 70% by weight or more, and the average molecular weight is
A polymer surfactant comprising a polymer (C) in the range of 1,000 to 500,000; and (b) a low molecular ionic surfactant having a hydrophobic group having 8 to 30 carbon atoms and an ionic group. A dispersant for reversed-phase suspension polymerization characterized by the following. 2. The ratio of the high molecular weight surfactant (a) and the low molecular weight ionic surfactant (b) in the dispersant is 70 to 70, respectively.
The dispersant according to claim 1, wherein the dispersant is 99% by weight and 1 to 30% by weight. 3. A hydrophilic polymer obtained by dispersing a water-soluble ethylenically unsaturated monomer or an aqueous solution thereof in a polymerization-inactive hydrophobic organic solvent and subjecting it to reverse phase suspension polymerization with a water-soluble radical polymerization initiator. 2. A method for producing a hydrophilic polymer, comprising using the dispersant according to claim 1 as a dispersant in an amount of 0.2 to 5 parts by weight per 100 parts by weight of the unsaturated monomer. Method. 4. The method for producing a hydrophilic polymer according to claim 3, wherein the inverse suspension polymerization is carried out in the presence of a crosslinking agent. 5. The method according to claim 1, wherein the water-soluble ethylenically unsaturated monomer is (meth)
From acrylic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid and salts thereof, dimethylaminoethyl (meth) acrylate and quaternized products thereof, and (meth) acrylamide The method for producing a hydrophilic polymer according to claim 3, wherein the method is one or more selected from the group consisting of: