JP2721658B2 - Method for producing polymer particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polymer particles which are particularly stable and are useful as a water-absorbent resin having high water absorbency and liquid permeability. More specifically, the present invention relates to an aqueous liquid or urine or menstrual blood. Also, the present invention relates to a method for producing polymer particles having a small degree of degradation and high stability even in a state where body fluids such as sweat are absorbed.

[0002]

2. Description of the Related Art Superabsorbent resins are used in the field of hygiene products such as absorbent articles such as disposable diapers for infants, adults or incontinent persons and sanitary napkins for women, and agricultural and horticultural fields. It is widely used as a water retention agent, a coagulant for sludge in the field of civil engineering, an anti-condensation agent, a water-stopping agent, and the like.

[0003] However, the water-soluble or swellable polymer constituting such a superabsorbent resin cannot be used in the presence of radical-generating species such as hydrogen peroxide and L-ascorbic acid (salt).
It is known that the molecular weight decreases / degrades over time. In particular, when the superabsorbent resin is used as an absorbent for disposable diapers and sanitary napkins, since L-ascorbic acid (salt) is also present in body fluids such as urine, menstrual blood, and sweat,
It is a serious problem that the superabsorbent resin in the absorbent such as a disposable diaper or a sanitary napkin is deteriorated and decomposed with time due to radical species generated from L-ascorbic acid (salt), and the body fluid holding ability is reduced. Has become.

The decomposition reaction of a water-soluble polymer or a crosslinked product thereof by the above radical-generating species is carried out in a water-containing state, in particular, in the presence of an air atmosphere, two or more transition metal ions such as iron and copper can coexist. It is remarkable under the condition.

The reason for this is that, for example, J. Am. Chem. Soc., 8
9, No. 16, 4176 (1967) and Free Radical Research Commun
As shown in ications, 1, No. 6, 349 (1986), a small amount of a transition metal ion such as iron or copper acts as a catalyst to decompose hydrogen peroxide or L-ascorbic acid or a salt thereof (radical generation). Reaction) is remarkably accelerated.

It is known that such metal ions can decompose the polymer chain of the water-soluble polymer with time similarly to radical-generating species such as hydrogen peroxide or L-ascorbic acid or a salt thereof ( For example, Carbohydrate Research,
4, 63 (1967).

[0007] As a method for suppressing the decomposition / deterioration of the superabsorbent resin, 1) sealing the superabsorbent resin under reduced pressure or under a nitrogen atmosphere to remove air (particularly oxygen);
2) Use of highly purified water and raw materials to prevent metal ions from being mixed into the superabsorbent resin. 3) Antioxidant or A reducing agent is added; 4) a protein or an enzyme is added to the superabsorbent resin; 5) citric acid, (poly) phosphoric acid or a salt thereof or ethylenediaminetetraacetic acid (EDTA) is added to the superabsorbent resin. Alternatively, a method of adding a metal chelating agent such as a salt thereof (corresponding to JP-A-63-146964, EP-A-257951) is widely used.

However, the above methods 1) and 2) are often impossible in practice depending on the purpose of use of the superabsorbent resin. In addition, the method of adding the existing additives as described in 3), 4) and 5) suppresses the decomposition / deterioration of the superabsorbent resin, but the effect is not always sufficient. In order to achieve the effect, it is often necessary to add the above-mentioned additive in a large amount, or to use an additive having a very strong effect. Under such circumstances, there is a problem that the original physical properties and functions of the superabsorbent resin are significantly impaired.

In fact, various additives have been proposed, for example, as disclosed in JP-A-63-272349 (EP-A-2).
68459, USP4959060), Tokuho 5
JP-A-34383 (EP-A-249391, USP
4972019), JP-A-2-255804 (corresponding to EP-A-372981), JP-A-3-17
Japanese Patent No. 9008 proposes a method using additives such as a sulfur-containing reducing agent, an oxygen-containing reducing inorganic salt, and a water-soluble chain transfer agent. However, these additives give off a bad smell or are stored for a long time. It has the disadvantage of poor stability.

Accordingly, an object of the present invention is to provide an absorbent resin having a small degree of decomposition / deterioration even after absorbing an aqueous liquid or a body fluid and having a high water absorption, without requiring a complicated operation as compared with the conventional method. An object of the present invention is to provide a manufacturing method which can be obtained by operation.

[0011]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that water-soluble polymerization is carried out in a dispersion system of a hydrophobic organic solvent inert to polymerization and an aqueous solution of a water-soluble polymerizable monomer. It has been found that the above object can be achieved by using a specific anionic surfactant as a dispersant when polymerizing a hydrophilic monomer.

The present invention has been made on the basis of the above findings, and is intended for use in polymerization of a water-soluble polymerizable monomer using a hydrophobic organic solvent inert to polymerization and an aqueous solution of a water-soluble polymerizable monomer. And a method for producing polymer particles characterized by including an anionic surfactant represented by the following general formula (I) as a dispersant. The polymer particles produced according to the present invention are generally non-spherical and irregular particles having irregularities on the surface.

[0013]

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[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below. Unless otherwise specified, all “%” in the text are “% by weight”.

The water-soluble polymerizable monomer used in the present invention includes an olefinically unsaturated carboxylic acid or a salt thereof, an olefinically unsaturated carboxylic acid ester, an olefinically unsaturated sulfonic acid or a salt thereof, an olefinically unsaturated phosphoric acid or Examples thereof include vinyl monomers having a polymerizable unsaturated group such as salts thereof, olefinically unsaturated amines, olefinically unsaturated ammonium salts, and olefinically unsaturated amides.

Examples of the olefinically unsaturated carboxylic acids or salts thereof include acrylic acid, methacrylic acid, maleic acid,
Examples thereof include unsaturated carboxylic acids such as fumaric acid and alkali salts thereof, and examples of the olefinically unsaturated carboxylic acid esters include methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, and hydroxyethyl (meth).
Acrylates and the like, and olefinically unsaturated sulfonic acids or salts thereof include (meth) acrylamidomethylpropanesulfonic acid, unsaturated sulfonic acids such as allylsulfonic acid, and alkali salts thereof.
Examples of the olefinically unsaturated phosphoric acid or salts thereof include (meth) acryloyl (poly) oxyethylene phosphates and alkali salts thereof, and examples of the olefinically unsaturated amines include dimethylaminoethyl (meth) acrylate and the like. And the olefinically unsaturated ammonium salts include (meth) acryloyloxyethylenetrimethylammonium halides and the like. The olefinically unsaturated amides include
(Meth) acrylamide, methyl (meth) acrylamide, ethyl (meth) acrylamide, propyl (meth)
Examples thereof include (meth) acrylamide derivatives such as acrylamide and vinylmethylacetamide. When used, they are used alone or as a mixture of two or more.
In addition, examples of the alkali salt include an alkali metal salt, an alkaline earth metal salt, and an ammonium salt.

In the present invention, among these, olefinic unsaturated carboxylic acids and their alkali salts are preferably used, and acrylic acid, methacrylic acid and their alkali metal salts or alkaline earth metal salts are more preferably used. .

The concentration of the water-soluble polymerizable monomer in the aqueous solution of the water-soluble polymerizable monomer is preferably 1 to 70%, more preferably 10 to 65%, and most preferably 30 to 60%.

In the present invention, as the polymerizable monomer, it is preferable to use the above-mentioned water-soluble polymerizable monomer alone or copolymerize it. However, a water-insoluble monomer copolymerizable with the above-mentioned water-soluble polymerizable monomer, for example, carbon Number 1
Unsaturated carboxylic acid ester monomers having an alkyl group of from 18 to 18 such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid can be used in an amount of 50% or less of all monomers.

The polymerization-inactive hydrophobic organic solvents used in the present invention include n-pentane, cyclopentane and n-pentane.
Aliphatic hydrocarbons such as hexane, cyclohexane, n-heptane and methylcyclohexane; aromatic hydrocarbons such as benzene and toluene; aliphatic alcohols having 4 to 6 carbon atoms such as n-butyl alcohol and n-amyl alcohol; methyl ethyl ketone And aliphatic esters such as ethyl acetate. When used, they may be used alone or as a mixture of two or more. The amount of the hydrophobic organic solvent used is preferably in the range of 50 to 500% based on the aqueous solution of the water-soluble polymerizable monomer.

In the present invention, an amphiphilic solvent other than the above-mentioned hydrophobic solvent may be used within a range not exceeding the amount of the above-mentioned hydrophobic solvent. As the amphiphilic solvent,
Alcohols such as methanol, ethanol, propanol and 2-propanol; ketones such as acetone; and ethers such as tetrahydrofuran and dioxane.

The anionic surfactant used in the present invention comprises:
An anionic surfactant represented by the general formula (I) (hereinafter, referred to as “anionic surfactant (I)”),
It is a derivative of aspartic acid or glutamic acid.

In the general formula (I), R ¹ has 5 to 29 carbon atoms, preferably 7 to 23 carbon atoms, and more preferably 11 to 23 carbon atoms. If the carbon number of R ¹ is more than 29, the water solubility is remarkably deteriorated, and if it is less than 5, the performance as a stabilizer of the superabsorbent resin is lowered. R ¹ is also preferably an alkyl group having 11 to 23 carbon atoms. Specific examples of the above R ¹ CO include a lauroyl group, a myristoyl group, a palmitoyl group, a stearoyl group, an eicosanoyl group, and a docosanoyl group. Further, it is preferable that n in the general formula (I) is 2.

The reason why the stability of the polymer obtained in the present invention is improved is not clear, but the anionic surfactant (I) is a compound capable of forming a chelate with a transition metal such as copper or iron. Therefore, the anionic surfactant remains in the polymer obtained by the production method of the present invention, and the transition metal ion acting as a catalyst for a decomposition reaction (radical generation reaction) such as L-ascorbic acid is chelated. It is considered that the stability of the superabsorbent resin in the water-absorbing state is improved by completely insolubilizing in water and completely blocking transition metal ions. Furthermore, since the anionic surfactant (I) is a compound using a naturally-occurring amino acid and a naturally-occurring fatty acid as raw materials, its safety is high,
It is also hypoallergenic. Therefore, there is no problem even when used in large quantities, and the polymer particles obtained by the production method of the present invention do not adversely affect the human body even when used in sanitary materials such as sanitary products and disposable diapers.

Examples of the anionic surfactant (I) include monosodium N-palmitoylaspartate, disodium N-palmitoylaspartate, N-palmitoylaspartic acid, monosodium N-myristoylglutamate, N-lauroyl glutamic acid monosodium salt, N-stearoyl glutamic acid monosodium salt, N-myristoyl glutamic acid monosodium salt, N-coconut oil fat-proofing acylglutamic acid monosodium salt, N-hardened tallow fatty acid acylglutamic acid monosodium salt, N-stearoyl Glutamic acid, monopotassium N-stearoylglutamate and the like can be mentioned. When used, they can be used alone or as a mixture. Examples of the anionic surfactant (I) include trade name “Amisoft HS-11”, trade name “LS-11”, trade name “MS-11”, trade name “GS-11”, and trade name “HK”. -11 ", product name" HS
-21 ", trade name" GS-21 "(all manufactured by Ajinomoto Co., Inc.), and aminosurfact (registered trademark, manufactured by Asahi Foods Co., Ltd.). Those synthesized by a known method can also be used.

Although the above-mentioned anionic surfactant (I) exhibits a sufficient effect even with a small amount of use, the amount of the anionic surfactant (I) used is limited to the amount of the water-soluble polymerizable monomer (100). It is preferably 0.01 to 10 parts by weight, more preferably 0.01 to 2 parts by weight, and even more preferably 0.05 to 1 part by weight with respect to parts by weight. The amount used is 0.01
If the amount is less than 10 parts by weight, not only can the amount of the dispersant be small and polymer particles cannot be stably obtained, but the ability to prevent degradation of the produced polymer is not sufficient, and even if it exceeds 10 parts by weight, Since it is not economically feasible to use an excess of the surfactant, it is preferable to set the amount in the above range.

The anionic surfactant (I) has a sufficient effect as a dispersant even when used alone, but may be further used in a mixture with other anionic surfactants or as a nonionic surfactant. A surfactant, a cationic surfactant, a zwitterionic surfactant or a polymer type dispersant may be used in combination. Among these, it is preferable to use another anionic surfactant in combination. As the other anionic surfactant described above, a surfactant represented by the following general formula (II) is preferably used because it can narrow the particle size distribution of polymer particles obtained. Anionic surfactants represented by the following general formula (III) are preferably used.

[0028]

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[0029]

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When the anionic surfactant (II) is used in combination with the anionic surfactant (I), the amounts of these anionic surfactants used are as follows. That is, the amount of the anionic surfactant (I) used is as described above, and the amount of the anionic surfactant (II) used is preferably based on 100 parts by weight of the water-soluble polymerizable monomer. Is 0.01 to 10 parts by weight, more preferably 0.01 to 2 parts by weight, still more preferably 0.02 to
１1 part by weight. Examples of the anionic surfactant represented by the general formula (III) include “Emal E-27C” (sodium polyoxyethylene lauryl ether sulfate) and “Emal 20C” (polyoxyethylene lauryl ether). Commercially available products such as sodium sulfate ester (all manufactured by Kao Corporation) may be used, and those synthesized by a known method may also be used.

The method for polymerizing the water-soluble polymerizable monomer using the hydrophobic organic solvent and the aqueous solution of the water-soluble polymerizable monomer may be any of the following methods. A method in which an aqueous solution of a water-soluble polymerizable monomer and a hydrophobic organic solvent are mixed at once and then polymerized (batch polymerization method). A method of sequentially polymerizing while dropping an aqueous solution of a water-soluble polymerizable monomer into a hydrophobic organic solvent (sequential polymerization method). A method (pre-dispersion method) in which a mixed solution obtained by previously mixing or dispersing an aqueous solution of a water-soluble polymerizable monomer with a part of a hydrophobic organic solvent is dropped into the hydrophobic organic solvent (pre-dispersion method). A method using the above methods in combination.

In the polymerization, the above-mentioned anionic surfactant may be present in the following methods (1) to (4).
The method shown in (4) can be mentioned. (1) A method in which an anionic surfactant is dispersed in a hydrophobic organic solvent in advance. (2) A method in which an anionic surfactant is previously dissolved or dispersed in an aqueous solution of a water-soluble polymerizable monomer. (3) A method of gradually adding an anionic surfactant while performing the above polymerization. (4) An addition method using a combination of the methods (1) to (3).

In the polymerization, it is preferable to use a polymerization initiator. Examples of the polymerization initiator include, but are not particularly limited to, ketone peroxides such as methyl ethyl ketone peroxide and methyl isobutyl ketone peroxide; dialkyl peroxides such as di-t-butyl peroxide and t-butyl cumyl peroxide; Alkyl peresters such as -butyl peracetate, t-butyl perisobutyrate, and t-butyl pivalate; hydroperoxides such as hydrogen peroxide such as t-butyl hydroperoxide and cumene hydroperoxide; potassium persulfate; Persulfates such as ammonium sulfate; perchlorates such as potassium perchlorate and sodium perchlorate; halogenates such as potassium chlorate and potassium bromate; 2- (carbamoylazo) -isobutyronitrile; -Azobis (N,
N'-dimethyleneisobutylamidine) dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 4,4'-azobis (4-
Cyanopentanoic acid), azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-
Dimethylvaleronitrile), (1-phenylethyl) azodiphenylmethane, dimethyl-2,2'azobisisobutyrate, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (1- Cyclo-hexanecarbonitrile), 2,2′-azobis (2,4,4 ′)
-Trimethylpentane), 2-phenylazo-2,4-
Examples thereof include azo compounds such as dimethyl-4-methoxyvaleronitrile and 2,2′-azobis (2-methylpropane). When used, they can be used alone or as a mixture of two or more.

Further, in the present invention, the above polymerization initiator may be used as a redox initiator system in combination with a reducing agent such as sulfite, L-ascorbic acid, ferrous salt and the like. Further, among the above-mentioned polymerization initiators, potassium persulfate and 2,2′-azobis (2-amidinopropane) dihydrochloride are preferably used. Further, the amount of the polymerization initiator used is, based on the water-soluble polymerizable monomer,
Usually, it is 0.01 to 10%, preferably 0.02 to 5%. The method of adding the polymerization initiator is not particularly limited, but it is preferable to add the polymerization initiator to the aqueous solution of the water-soluble polymerizable monomer in advance. The polymerization temperature in the above polymerization is usually 2
A range of 0 to 120C, preferably 40 to 100C is appropriate. If the temperature exceeds 120 ° C., the crosslinking becomes extremely high, so that the water absorbing ability of the polymer particles is extremely lowered. If the temperature is lower than 20 ° C., the polymerization rate is extremely lowered, which is not preferable.

In the present invention, any known crosslinking agent can be added before, during or after the polymerization. For example, as the crosslinking agent, polyallyl compounds such as N, N-diallylacrylamide, diallylamine, diallyl methacrylamide, diallyl phthalate, diallyl malate, diallyl terephthalate, triallyl cyanurate, triallyl phosphate; divinylbenzene, N, Polyvinyl compounds such as N-methylenebisacrylamide, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, glycerin trimethacrylate; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerin polyglycidyl Polyglycidyl ethers such as ethers; epichlorohydrin, α-methyl Haloepoxy compounds such as lorhydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyols such as glycerin; polyamines such as ethylenediamine; hydroxyvinyl compounds such as 2-hydroxyethyl methacrylate; and polyvalent ions such as calcium, magnesium, zinc and aluminum. The resulting inorganic salt or organic metal salt can be used. Further, in the present invention, a monoglycidyl compound such as phenol polyoxyethylene glycol ether can be used as a modifier. When the above-mentioned crosslinking agent or the above-mentioned modifier is used, the amount of these used can be any amount according to the desired properties of the final product polymer, but is usually 0.01 to 10 to the produced polymer. % Is preferable.

In carrying out the production method of the present invention, the polymer particles obtained by using a polymer compound having a functional group may be subjected to a surface treatment. Examples of the polymer compound include polyethyleneimine , Polyvinyl alcohol, polyallylamine and the like.
The polymer compound may be used alone or in combination with the various crosslinking agents described above.

In the present invention, the anionic surfactant (I) alone is sufficiently effective in preventing the decomposition of the water-absorbing resin, but another compound for preventing the decomposition of the water-absorbing resin is separately added. You may. The method of addition when using the other compound described above is not particularly limited as long as it can be uniformly added to the water-absorbent resin, a method of mixing with the aqueous solution of the water-soluble polymerizable monomer in the polymerization step, The above-mentioned other compounds can be added and used by a method of mixing, a method of adding the polymer obtained by polymerization by spraying as a solid, an aqueous solution or a dispersion, or the like. Further, the anionic surfactant (I) may be similarly added to the polymer after polymerization.

The polymer produced as described above is dried directly after polymerization or after removing the solvent by decantation or centrifugation, and then dried using a means such as a reduced-pressure drier or a fluidized drier and, if necessary, pulverized. By performing a granulation treatment or the like, amorphous polymer particles can be obtained.

The above-mentioned polymer particles obtained by the production method of the present invention are effectively used for applications in combination with radical-generating species such as ascorbic acid in cosmetics, food additives and the like. It is useful for applications of highly water-absorbing resins such as absorbents for sanitary articles such as disposable diapers and sanitary napkins that require high safety.

Although the details of the mechanism by which the polymer particles obtained by the production method of the present invention become amorphous are not known, the polymer obtained by ordinary O / W suspension polymerization or emulsion polymerization is a spherical polymer. On the other hand, as seen in JP-A-6-93008 (corresponding to EP-A-586976),
By using an anionic surfactant for the polymerization of the water-soluble monomer, the polymerization proceeds in a slightly unstable W / O system, and has a large number of voids and an irregular shape. It is believed that the retained polymer particles are formed.

The polymer particles obtained by the production method of the present invention can be produced in a body fluid such as urine, menstrual blood, sweat, etc., even when produced by reducing the amount of the crosslinking agent to increase the water absorption. Shows stability. In addition, since it is an amorphous polymer having a high porosity, it has excellent liquid permeability and gel strength, and is suitable as a highly water-absorbent resin used for absorbent articles of sanitary materials such as sanitary products and disposable diapers.

[0042]

The present invention will be described below in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The test methods performed in the examples and comparative examples are as follows. [Calculation method of average particle size] 100 g of the polymer is JIS Z
The particles were classified using a sieve conforming to -8801-1982, and the average particle size was determined from the weight fraction of each fraction.

[Method for measuring equilibrium swelling water absorption] 1 g of polymer
Was dispersed in a large excess of physiological saline (0.9% saline), and the polymer was swollen until its water absorption reached an equilibrium state. Then, the physiological saline was filtered through an 80 mesh wire mesh,
The weight (W) of the obtained swollen polymer is measured, and a value obtained by dividing this value by the polymer weight W ₀ before water absorption, that is,
W / W ₀ was taken as the equilibrium swelling water absorption.

[Method of Measuring Water Absorption Representing Water Absorption Rate] Using a device 1 (DemandWettability Tester) shown in FIG. 1 which is generally known as a device for performing the DW method, a physiological saline solution was used as shown in FIG. 0.3 g of polymer P was sprayed on a polymer spraying table 2 (70 mmφ, a table on which a No2 filter paper was placed on a glass filter No. 1) with the liquid level of W set at an equal water level, and the water absorption at the time of spraying the polymer was 0%. The water absorption after 60 seconds (this water absorption is measured on the scale of the burette 3 indicating the amount of decrease in the water level of the physiological saline solution W) is measured, and this value is used as the water absorption (ml) indicating the water absorption speed. And

[Flow rate of physiological saline] The polymer P0.5 was introduced into the apparatus 10 shown in FIG. 2 (a burette composed of a glass cylindrical tube having an inner diameter of 25.6 mm and a length of about 500 mm (cylindrical portion)).
g, and an excess amount of physiological saline W was used to equilibrate and swell the polymer P. The liquid level was adjusted to 200 ml from the lower part, and a cock was placed. It was confirmed that the swollen polymer P had sufficiently settled as shown in the figure. After confirming that the cock is open, the physiological saline W is between the two marked lines L (point 150 ml from the bottom) and M (point 100 ml from the bottom) shown in the figure (liquid volume 50 ml).
Measure the time required to pass through and measure the liquid volume (ml) between the marked lines.
(min) to obtain the liquid passing rate (ml / min).

[Stability of polymer particles] 1 g of a polymer was swollen with 45 g of a physiological saline solution containing 0.05% by weight of L-ascorbic acid, put into a screw tube, and placed in a thermostat at 40 ° C. And the state of the gel after 3 hours was observed. The scale of the stability evaluation was the following four levels. A: The swollen particles have neither fluidity nor spinnability and show the same shape. ；: The swollen particles have some fluidity and spinnability, but show the shape as they are. C: Although not dissolved, the swollen particles have fluidity and spinnability, and the shape becomes unclear. X: Partial dissolution occurs, a liquid state is observed, and more than half of the particles do not leave a shape. In this evaluation, ○ or more indicates that the composition is suitable as a water-absorbing polymer used for sanitary napkins, disposable diapers, adult sheets, tampons, sanitary cotton, and the like.

Example 1 72.1 g of acrylic acid was added to 1
After diluting with 8.0 g of water and neutralizing with 98.9 g of a 30 wt% aqueous sodium hydroxide solution while cooling, 10.7 g of a 2.8 wt% aqueous potassium persulfate solution as an initiator and an epoxy-based crosslinking agent [poly Glycerol polyglycidyl ether, manufactured by Nagase Kasei Co., Ltd., trade name "Denacol EX"
-512 "] 1 g of a 0.36% aqueous solution was added to make a homogeneous solution to obtain a monomer / initiator aqueous solution. Separately, 500 ml equipped with a reflux condenser, a dropping funnel, a stirring rod and a nitrogen inlet tube
283 ml of cyclohexane was placed in the flask, and an aqueous solution obtained by dissolving 1.76 g of acylated sodium grilltamic acid [trade name “Amisoft HS-11” manufactured by Ajinomoto Co., Ltd.] in 6.2 g of water was added, followed by stirring (300 rpm). Disperse,
After purging the flask with nitrogen, the bath temperature was raised to 75 ° C. Next, the monomer / initiator aqueous solution was dropped into the flask over 60 minutes. After completion of the dropwise addition of the monomer / initiator aqueous solution, the mixture was heated and stirred at 75 ° C. for 0.25 hours,
Further, the mixture was stirred and polymerized for 2 hours at a bath temperature of 80 ° C. At this time, only water was continuously removed from the azeotropic reflux liquid of cyclohexane and water to the outside of the system, and the water content of the water-absorbent resin was reduced to 10%.
The amount was adjusted to 30 parts by weight or less with respect to 0 parts by weight. After the polymerization is completed, the product is separated and dried under reduced pressure to obtain a product.
8.4 g of amorphous granulated gel partially crosslinked acrylic acid (sodium) polymer particles were obtained. About the obtained amorphous polymer particles, the average particle diameter, the equilibrium swelling water absorption, the water absorption indicating the water absorption rate, the flow rate of physiological saline, and the stability of the amorphous polymer particles were measured. The results are shown in [Table 1].

Example 2 1.3 wt% of 2,2'-azobis (2
-Amidinopropane) dihydrochloride aqueous solution 5.4 g
In the same manner as in Example 1 except that the above-mentioned was used, amorphous granulated gel partially crosslinked acrylic acid (sodium) polymer particles were obtained. About the obtained amorphous polymer particles, Example 1
The same measurement was performed. The results are shown in [Table 1].

Example 3 To the aqueous monomer / initiator solution described in Example 1, an aqueous solution in which 1.76 g of acylated sodium glutamate (Amisoft HS-11) was dissolved in 6.2 g of water was further added to form a uniform solution. To obtain a monomer / initiator / dispersant aqueous solution. Separately, 283 ml of cyclohexane was placed in a 500 ml flask equipped with a reflux condenser, a dropping funnel, a stirring rod, and a nitrogen inlet tube, stirred (300 rpm) and dispersed, and the flask was purged with nitrogen. Then, the bath temperature was raised to 75 ° C. . The above monomer / initiator / dispersant aqueous solution was added dropwise thereto over 60 minutes. Otherwise, in the same manner as in Example 1, irregularly-shaped granular gel partially crosslinked acrylic acid (sodium) polymer particles were obtained. The same measurement as in Example 1 was performed on the obtained amorphous polymer particles. The results are shown in [Table 1].

Example 4 An aqueous solution obtained by dissolving 1.76 g of acylated sodium glutamate (Amisoft HS-11) in 6.2 g of water and polyoxyethylene lauryl were added to the aqueous monomer / initiator solution described in Example 1. 0.29 g of a 25 wt% aqueous solution of sodium salt of ether sulfate (average number of moles of ethylene oxide added = 2) was added to form a uniform solution, and a monomer / initiator / dispersant aqueous solution was obtained. Amorphous and granular gel partially crosslinked acrylic acid (sodium) polymer particles were obtained in the same manner as in Example 1 except that the aqueous solution was used in place of the initiator aqueous solution. About the obtained amorphous polymer particles,
The same measurement as in Example 1 was performed. The results are shown in [Table 1].

Example 5 283 ml of cyclohexane was placed in a 500 ml flask equipped with a reflux condenser, a dropping funnel, a stirring bar, and a nitrogen inlet tube, and sodium polyoxyethylene lauryl ether sulfate (average number of moles of ethylene oxide added = 2). ) Of a 25% by weight aqueous solution of an acylated sodium grillitamate (Amisoft HS-1)
1) A solution prepared by dissolving 1.76 g in 6.2 g of water was added, and the mixture was stirred (300 rpm) and dispersed. After the flask was replaced with nitrogen, the bath temperature was raised to 75 ° C. To this was added dropwise the monomer / initiator aqueous solution described in Example 1 over 60 minutes.
Except for this, similarly to Example 1, amorphous and partially crosslinked acrylic acid (sodium) polymer particles of granular gel were obtained.
The same measurement as in Example 1 was performed on the obtained amorphous polymer particles. The results are shown in [Table 1].

Example 6 To a monomer / initiator aqueous solution described in Example 1 was added 0.29 g of a 25 wt% aqueous solution of polyoxyethylene lauryl ether sulfate sodium salt (average number of moles of ethylene oxide added = 2) to obtain a homogeneous solution. To obtain an aqueous monomer / initiator solution. Except for this, similarly to Example 1, amorphous and partially crosslinked acrylic acid (sodium) polymer particles of granular gel were obtained. The same measurement as in Example 1 was performed on the obtained amorphous polymer particles. The results are shown in [Table 1].

Example 7 An aqueous solution obtained by dissolving 1.76 g of acylated sodium glutamate (Amisoft HS-11) in 6.2 g of water was added to the aqueous monomer / initiator solution described in Example 1 to form a homogeneous solution. An aqueous monomer / initiator / dispersant solution was obtained. Separately, 283 ml of cyclohexane was placed in a 500 ml flask equipped with a reflux condenser, a dropping funnel, a stir bar, and a nitrogen inlet tube, and a 25 wt% aqueous solution of sodium salt of polyoxyethylene lauryl ether sulfate (average ethylene oxide addition moles = 2) was added. .29 g was added, and the mixture was stirred (300 rpm) and dispersed. After the atmosphere in the flask was replaced with nitrogen, the bath temperature was raised to 75 ° C. The above-mentioned monomer / initiator / dispersant aqueous solution was added dropwise thereto over 60 minutes. Except for this, similarly to Example 1, amorphous and partially crosslinked acrylic acid (sodium) polymer particles of granular gel were obtained. The same measurement as in Example 1 was performed on the obtained amorphous polymer particles. The results are shown in [Table 1].

Example 8 An aqueous solution obtained by dissolving 0.44 g of acylated sodium glutamate (Amisoft HS-11) in 1.55 g of water was added to the aqueous monomer / initiator solution described in Example 1 to form a homogeneous solution. An aqueous monomer / initiator / dispersant solution was used. Separately, a reflux condenser, a dropping funnel, a stirring rod,
Then, 283 ml of cyclohexane was placed in a 500 ml flask equipped with a nitrogen inlet tube, 1.32 g of acylated sodium glutamate (Amisoft HS-11) and 4.65 g of water were added, and the mixture was stirred (300 rpm) and dispersed. The bath temperature was raised to 75 ° C. The monomer / initiator / dispersant aqueous solution was added dropwise thereto over 60 minutes. Except for this, in the same manner as in Example 1, amorphous granulated gel partially crosslinked acrylic acid (sodium) polymer particles were obtained. About the obtained amorphous polymer particles, Example 1
The same measurement was performed. The results are shown in [Table 1].

Comparative Example 1 A spherical polymer was obtained in the same manner as in Example 1 except that 0.9 g of ethyl cellulose was used instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant. Was. About the obtained polymer,
The same measurement as in Example 1 was performed. The results are shown in [Table 1].

Comparative Example 2 In place of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant, sorbitan monostearate (trade name “Leodol SP-
S10 ") A spherical polymer was obtained in the same manner as in Example 1 except that 2.9 g was used. The same measurement as in Example 1 was performed for the obtained polymer. The results are shown in [Table 1].

Comparative Example 3 25 wt% of polyoxyethylene lauryl ether sulfate sodium salt (average number of moles of ethylene oxide added = 2) was used instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant.
An amorphous polymer was obtained in the same manner as in Example 1 except that 0.87 g of the aqueous solution was used. About the obtained polymer,
The same measurement as in Example 1 was performed. The results are shown in [Table 1].

[0059]

[Table 1]

Example 9 72.1 g of acrylic acid was added to 1
It was diluted with 8.0 g of water, neutralized with 98.9 g of a 30 wt% aqueous sodium hydroxide solution while cooling, and then 1.3 wt%
5.4 g of a 2,2′-azobis (2-amidinopropane) dihydrochloride aqueous solution was added to make a uniform solution, and a monomer / initiator aqueous solution was obtained. Separately, 283 ml of cyclohexane was placed in a 500 ml flask equipped with a reflux condenser, a dropping funnel, a stir bar, and a nitrogen inlet tube, and 1.76 g of acylated sodium grillimate (Amisoft HS-11) and 6.2 g of water were added, followed by stirring. (300 rpm) After dispersing and replacing the flask with nitrogen, the bath temperature was raised to 75 ° C.
To this, the monomer / initiator aqueous solution was dropped over 60 minutes. After completion of the dropwise addition of the monomer / initiator aqueous solution, the bath temperature was heated and stirred at 75 ° C. for 0.25 hours.
The temperature was raised to 0 ° C., and the mixture was stirred and polymerized for 2 hours.

At this time, only water was continuously removed from the azeotropic reflux liquid of cyclohexane and water to the outside of the system, and the water content of the water-absorbing resin was adjusted to 30 parts by weight or less based on 100 parts by weight of the water-absorbing resin. 1.8 g of a 1.55% aqueous solution of an epoxy-based cross-linking agent (polyglycerol polyglycidyl ether, trade name "Denacol EX-512", manufactured by Nagase Kasei Co., Ltd.) is added to cyclohexane in which the water-absorbent resin-hydrate is dispersed for 5 minutes. After reacting for 120 minutes, the reaction product was taken out, separated, and dried under reduced pressure to obtain 88.4 g.
Amorphous and granular gel partially crosslinked acrylic acid (sodium) polymer particles were obtained. The equilibrium swelling water absorption, water absorption rate, liquid passing rate, and stability of the amorphous polymer particles obtained were measured. The evaluation results are shown in [Table 2].

Example 10 The monomers described in Example 9
0.007 g of an epoxy-based cross-linking agent (polyglycerol polyglycidyl ether, manufactured by Nagase Kasei Co., Ltd., trade name “Denacol EX-512”) was added to the initiator aqueous solution to form a uniform solution, and a monomer / initiator aqueous solution was used. In the same manner as in Example 9, partially-crosslinked acrylic acid (sodium) polymer particles of amorphous and granular gel were obtained. The same measurement as in Example 9 was performed on the obtained amorphous polymer particles. The results are shown in [Table 2].

[Examples 11 to 23] Except that the dispersants shown in [Table 2] were used in the amounts shown in [Table 2] and the amount of water added to the flask was changed to the amount shown in [Table 2]. Example 9
In the same manner as in the above, amorphous polymer particles were obtained. The same measurement as in Example 9 was performed on each of the obtained amorphous polymer particles. The results are shown in [Table 2].

The dispersant (monosodium N-palmitoyl-aspartate) used in Example 23 was synthesized as follows. 100 g of palmitic acid was dissolved in 780 ml of carbon tetrachloride, and 31.3 g of sulfuric anhydride was added dropwise while stirring at -0.5 to 0 ° C. After dropping,
The mixture was further reacted for 60 minutes to obtain a mixed acid anhydride of palmitic acid and sulfuric acid. 52.0 g of L-aspartic acid was suspended in a mixed solvent of 280 ml of water and 188 ml of acetone.
3 g of sodium hydroxide was added to obtain an L-aspartic acid disodium salt solution. Then, 117 ml of 46.9 g of sodium hydroxide was added to the mixed anhydride of palmitic acid and sulfuric acid.
Together with an aqueous solution dissolved in water under ice-cooling.
After the completion of the dropwise addition, the mixture was further stirred for 1 hour. Next, after distilling off the organic solvent under reduced pressure, the pH was adjusted to 1 with 6N sulfuric acid, and the precipitated crude crystals of N-palmitoyl-L-aspartic acid were filtered off, dried and washed with petroleum benzene. Thereafter, the resultant was further dried, and the solvent was distilled off.
Was dissolved in 50 g of water, put into a kneader, 11.34 g of sodium hydrogen carbonate was added, and the mixture was kneaded at a product temperature of 50 ° C. for 1 hour.
Drying under reduced pressure (150 mmHg, 85 ° C.) gave 52 g of N-palmitoyl-aspartic acid monosodium salt.

[0065]

[Table 2]

The structure of the anionic surfactant (I) as a dispersant used in the examples is shown below, and the types of the substituents in the structure are shown in [Table 3].

[0067]

Embedded image

[0068]

[Table 3]

Comparative Example 4 A spherical polymer was obtained in the same manner as in Example 9 except that 0.9 g of ethylcellulose was used instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant. Was. About the obtained polymer,
The same measurement as in Example 9 was performed. The results are shown in [Table 4].

Comparative Example 5 0.9 g of ethyl cellulose was used in place of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant, and the concentration of an aqueous solution of an epoxy crosslinking agent dropped into a cyclohexane solution after the polymerization was completed. Was changed from 1.55% to 5.81%, and a spherical polymer was obtained in the same manner as in Example 9. The same measurement as in Example 9 was performed on the obtained polymer. The results are shown in [Table 4].

Comparative Example 6 2.9 g of sorbitan monostearate (Rhodol SP-S10) was used instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant.
Except for using, a spherical polymer was obtained in the same manner as in Example 9. The same measurement as in Example 9 was performed on the obtained polymer. The results are shown in [Table 4].

[Comparative Example 7] Instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant, sorbitan monostearate (Rhodol SP-S10) 2.9 was used.
g in the same manner as in Example 9 except that the concentration of the aqueous solution of the epoxy-based crosslinking agent dropped into the cyclohexane solution after the polymerization was changed from 1.55% to 5.81%. A coalescence was obtained. The same measurement as in Example 9 was performed on the obtained polymer. The results are shown in [Table 4].

Comparative Example 8 25 wt% of polyoxyethylene lauryl ether sulfate sodium salt (average ethylene oxide addition mole number = 2) was used instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant.
An amorphous polymer was obtained in the same manner as in Example 9 except that 0.87 g of the aqueous solution was used. The same measurement as in Example 9 was performed on the obtained polymer. The results are shown in [Table 4].

Comparative Example 9 25 wt% of polyoxyethylene lauryl ether sulfate sodium salt (average ethylene oxide addition mole number = 2) was used instead of an aqueous solution in which acylated sodium glutamate was dissolved in water as a dispersant.
The same procedure as in Example 9 was repeated except that 0.87 g of the aqueous solution was used, and the concentration of the aqueous solution of the epoxy crosslinking agent dropped into the cyclohexane solution after the polymerization was changed from 1.55% to 5.81%. A shaped polymer was obtained. The same measurement as in Example 9 was performed on the obtained polymer. The results are shown in [Table 4].

[0075]

[Table 4]

Example 24 The monomers described in Example 1
A solution obtained by dissolving 0.088 g of acylated sodium glutamate (Amisoft MS-11) in 0.8 g of water was added to the aqueous initiator solution to form a uniform solution, and a monomer / initiator aqueous solution was obtained. Separately, 283 ml of cyclohexane was placed in a 500 ml flask equipped with a reflux condenser, a dropping funnel, a stirring rod, and a nitrogen inlet tube, and a 25 wt% aqueous solution of polyoxyethylene (average EO addition mole number: 2.8 mol) dodecyl ether sulfate sodium salt was added. [Product name Emar 20C:
(Manufactured by Kao Corporation)] and stirred (300 rpm)
m) After dispersing and replacing the flask with nitrogen, the bath temperature was raised to 75 ° C. Next, the monomer / initiator aqueous solution was dropped into the flask over 60 minutes. Other procedures were the same as in the method described in Example 1 to obtain a granular gel having a distorted shape. The same measurement as in Example 1 was performed for the obtained polymer. The results are shown in [Table 5]. The obtained product had a narrow particle size distribution and a high liquid passing speed.

Example 25 The monomers described in Example 1
A solution prepared by dissolving 0.044 g of acylated sodium glutamate (Amisoft MS-11) in 0.8 g of water was added to the aqueous initiator solution to obtain a uniform solution, and an aqueous monomer / initiator solution was obtained. Separately, cyclohexane 28 was placed in a 500 ml flask equipped with a reflux condenser, a dropping funnel, a stirring rod, and a nitrogen inlet tube.
Take 3 ml of polyoxyethylene (average number of moles of EO added: 2 mol) alkyl (dodecyl 75%; tetradecyl 2
5%) 27 wt% of ether sulfate sodium salt
Aqueous solution [trade name Emar E-27C: manufactured by Kao Corporation]
Add 0.27 g, stir (300 rpm) and disperse,
After purging the flask with nitrogen, the bath temperature was raised to 75 ° C. Next, the monomer / initiator aqueous solution was dropped into the flask over 60 minutes. Other procedures were the same as in the method described in Example 1 to obtain a granular gel having a distorted shape. The same measurement as in Example 1 was performed for the obtained polymer. The results are shown in [Table 5]. The obtained product had a narrow particle size distribution and a high liquid passing speed.

[0078]

[Table 5]

[0079]

According to the method for producing polymer particles of the present invention, an absorbent resin having a small degree of decomposition / deterioration even after absorbing an aqueous liquid or a body fluid and having a high water absorption can be prepared as compared with the conventional method. It can be obtained by a simple operation that does not require a complicated operation. More specifically, the polymer particles obtained by the production method of the present invention are non-spherical, JIS Z-8801-198.
2 is an amorphous polymer having a high porosity with an average particle size of 10 μm or more as measured by a sieving method according to No. 2, and therefore, in a water-absorbent resin which is an aggregate of the polymer particles, water absorption rate, air permeability, And excellent gel strength after water absorption, and even in an aqueous solution state in which radical generating species such as hydrogen peroxide and L-ascorbic acid, and transition metals such as iron and copper are present or in the presence of moisture. The water-absorbent resin has a small degree of deterioration / decomposition, is excellent in stability, and has high safety for biological systems.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a water absorption rate measuring device used in Examples and Comparative Examples.

FIG. 2 is a schematic diagram showing a measuring device for measuring the flow rate of physiological saline used in Examples and Comparative Examples.

[Description of Signs] 1 Measurement device for polymer water absorption rate 2 Polymer spraying agent 3 Burette 10 Measurement device for flow rate of physiological saline W Physiological saline P Polymer M, L Marked line

Claims (8)

(57) [Claims] When a water-soluble polymerizable monomer is polymerized using a hydrophobic organic solvent inert to polymerization and an aqueous solution of a water-soluble polymerizable monomer, a compound represented by the following general formula (I) is used as a dispersant. A method for producing polymer particles, characterized by allowing an anionic surfactant to be present. Embedded image 2. The method according to claim 1, wherein R ¹ in the general formula (I) is an alkyl group having 11 to 23 carbon atoms. 3. The method for producing polymer particles according to claim 1, wherein n in the general formula (I) is 2. 4. The method according to claim 1, wherein the dispersant is used in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the water-soluble polymerizable monomer. 5. The method according to claim 4, wherein the dispersant is used in an amount of 0.05 to 1 part by weight based on 100 parts by weight of the water-soluble polymerizable monomer. 6. The water-soluble polymerizable monomer is an olefinically unsaturated carboxylic acid or an alkali salt thereof.
A method for producing the polymer particles as described above. 7. The dispersant further includes a compound represented by the following general formula (I)
The method for producing polymer particles according to claim 1, wherein the surfactant represented by I) is used in combination. Embedded image 8. The polymer particles according to claim 7, wherein the amount of the surfactant represented by the general formula (II) is 0.01 to 10 parts by weight based on 100 parts by weight of the water-soluble polymerizable monomer. Production method.