JPH066614B2 - Method for producing spherical cross-linked polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention can be used for applications such as artificial soil for hydroponics and soil modifier from (meth) acrylamides and crosslinkable monomers. And a method for producing a water-swellable gel-like crosslinked polymer having excellent transparency and having a spherical shape, or a water-swellable crosslinked polymer obtained by drying the same.

[Conventional technology]

Conventionally, as a method for producing a water-swellable crosslinked polymer from (meth) acrylamides and a crosslinkable monomer, acrylamide and N are disclosed in, for example, JP-A-56-145908 and JP-A-53-145893. A method of polymerizing N'-methylenebisacrylamide in an aqueous solution in the presence of a radical polymerization initiator has been proposed.

Further, the present applicant has proposed a new method for producing a crosslinked polymer having a uniform particle shape in order to use the water-swellable gel-like crosslinked polymer or the water-swellable crosslinked polymer as a horticultural soil. No. 4-25297). However, in these conventional methods, the following method must be adopted in order to form the obtained water-swelling gel-like crosslinked polymer into a desired shape, and moreover, the spherical water-swelling gel-like crosslinkable polymer is used. There is a problem that can not be obtained. That is, as a conventional method, a monomer aqueous solution containing a monomer mixture is continuously fed into a heated predetermined cylindrical tube to polymerize, and a strand-shaped water-swelling gel-like cross-linked polymer obtained has a predetermined length. Method (Chubbler method) or a large lump (ingot) cross-linked polymer obtained by polymerizing an aqueous monomer solution in a casting of a predetermined size, and cutting it vertically and horizontally to obtain various shapes. There is a method (ingot method), but for example, in the tumbler method, the length of the polymerization tube is limited due to the clogging of the product, and in the ingot method, the cutting is troublesome. The obtained water-swelling gel-like cross-linked polymer and the like has the drawback that its shape is columnar and its productivity is low.

[Problems to be solved by the invention]

The present inventors have recognized that the conventional method for producing a water-swellable gel-like cross-linked polymer or a water-swellable cross-linked polymer has the above-mentioned problems, for example, a preferable spherical shape when used as an artificial soil for gardening. In addition, a method for efficiently producing a water-swellable gel-like crosslinked polymer having a relatively large spherical shape and having a high transparency when swollen by absorbing water or a water-swellable crosslinked polymer obtained by drying the same was examined.

[Outline of Invention]

As a result, they have found the following method and completed the present invention. That is, according to the method of the present invention, an aqueous solution containing (meth) acrylamides (a), a crosslinkable monomer (b) and a radical polymerization initiator (c), a higher resin acid salt, a higher fatty acid amide, A particle size of 1 to 20 mm characterized by reacting while dispersing in a non-aqueous dispersion medium (e) in the presence of a dispersant (d) selected from the group consisting of higher fatty acid ester, polyoxyethylene alkylphenol ether and gelatin A method for producing a spherical cross-linked polymer is provided.

[Monomer component]

In the method of the present invention, a monomer component composed of (meth) acrylamides (a) and a crosslinkable monomer (b) is used as a starting material for the reaction.

The (meth) acrylamides (a) in this case are acrylamide, methacrylamide, or N-alkyl-substituted products thereof, and specifically include acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N. -Methylmethacrylamide, N, N-dimethylmethacrylamide and the like can be exemplified. Among these (meth) acrylamides, acrylamide or methacrylamide is preferable.

Further, as the crosslinkable monomer (b) which is another raw material monomer component, specifically, N, N′-methylenebis (meth) acrylamide, N, N′-ethylenebis (meth) acrylamide, N,
Bis (meth), such as N'-propylene bis (meth) acrylamide, N, N'-hexamethylene bis (meth) acrylamide, N, N'-phenylene bis (meth) acrylamide
Acrylamides, bis (meth) acrylates such as ethylene bis (meth) acrylate, propylene bis (meth) acrylate, hexamethylene bis (meth) acrylate, diethylene glycol bis (meth) acrylate, triethylene glycol bis (meth) acrylate, polyethylene Glycol bis (meth) acrylate and the like can be exemplified, and two or more kinds of mixed components may be used. Among these crosslinkable monomer components, N, N'-methylenebis (meth) acrylamide is particularly preferable.

The monomer component used in the method of the present invention may be composed of only the above-mentioned essential monomers, or may contain a small amount of an unsaturated monomer capable of copolymerization. Examples of the copolymerizable unsaturated monomer include ordinary unsaturated monomers such as acrylic acid, methacrylic acid, maleic acid, acid anhydrides, salts or esters of these acids, vinyl acetate, styrene and vinyltoluene. Can be illustrated. Further, in order to impart algae-proof, mildew-proof or colorability to the finally obtained water-swellable crosslinked polymer, a vinyl bond-containing triazine derivative, a vinyl bond-containing organotin compound or the like is added to the monomer mixture. It is also possible to copolymerize by adding an unsaturated monomer component such as the algae-proof unsaturated monomer, the antifungal unsaturated monomer or the coloring unsaturated monomer.

The ratio of the crosslinkable monomer (b) used in the method of the present invention is 0.1 with respect to 100 mol of the (meth) acrylamides (a).
01 to 5 mol range, more preferably 0.05 to 3
It is in the molar range. When the proportion of the crosslinkable monomer (b) is less than 0.01 mol, the water-swellable crosslinkable polymer becomes too soft, supporting the plant when used in applications such as artificial soil for hydroponics. When it is more than 5 mol, the water-swellable crosslinked polymer remarkably becomes cloudy and the transparency is lowered, and the appearance is deteriorated when it is used for the above purpose. The ratio of the other copolymerizable unsaturated monomer copolymerized as necessary is usually 0.01 to 60 mol, preferably 1 to 40 mol, based on 100 mol of the (meth) acrylamide (a). Is the range.

Radical polymerization initiator Radical polymerization initiator used in the method of the present invention
(c) is water-soluble, and specific examples thereof include ammonium persulfate, potassium persulfate, and sodium persulfate, and these can also be used as a mixture of two or more kinds. If necessary, amines such as triethanolamine and 3-dimethylaminopropionitrile may be used in combination with this radical initiator.

[Reaction method]

In the method of the present invention, an aqueous solution containing the above-mentioned monomers (a) and (b) and a radical polymerization initiator (c) is treated with salts derived from higher fatty acids, amides and esters, and polyoxyethylene alkylphenol ethers. The spherical water-swelling gel-like crosslinked polymer is obtained by reacting while dispersing in the non-aqueous dispersion medium (e) in the presence of the dispersant (d) selected from the group consisting of gelatin.

Dispersant The dispersant (d) used in the method of the present invention is a dispersant selected from the group consisting of higher fatty acid salts, higher fatty acid amides, higher fatty acid derivatives such as higher fatty acid esters, polyoxyethylene alkylphenol ethers and gelatin. is there.

Specific examples of the higher fatty acid component constituting the higher fatty acid derivative include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, ricinoleic acid, and 12-hydroxystearic acid having 12 to 22 carbon atoms substituted or non-substituted. Substituted higher saturated fatty acids, and 2-dodecenoic acid, 2
-Heptadecenoic acid, oleic acid, erucic acid, etc. with 12 carbon atoms
Examples of the substituted or unsubstituted higher unsaturated fatty acids include: Of these higher fatty acids, stearic acid, ricinoleic acid, 12-hydroxystearic acid, and erucic acid are preferably used in the present invention. Specific examples of the higher fatty acid salt include alkali metals such as lithium, sodium, potassium and rubidium, alkaline earth metals such as magnesium, calcium, strontium and barium, and zinc, manganese, iron, zirconium, copper, cadmium and cobalt. Examples thereof include higher fatty acid metal salts composed of salts of heavy metals such as selenium, aluminum, tin and lead (metal soap). In the present invention, among the higher fatty acid metal salts, especially lithium, calcium,
It is preferable to use a higher fatty acid metal salt selected from magnesium and zinc.

Specific examples of the higher fatty acid amide that can be used as a dispersant in the method of the present invention include ethylenebisstearamide, erucic acid amide, and oleic acid amide. Among them, oleic acid amide is preferable.

Specifically as the higher fatty acid ester used as a dispersant in the method of the present invention, polyoxyethylene glycol laurate, stearate, polyoxyalkylene glycol ester of the higher fatty acid such as oleate, or sorbitan laurate, palmitate, Sorbitan esters of higher fatty acids such as stearate and oleate, or polyoxyethylene sorbitan laurate,
Polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan oleate, and other polyoxyethylene sorbitan esters of the above-mentioned higher fatty acids [bonded to sorbitan In the polyoxyethylene group, n is preferably an integer of 1 to 20], and glyceride which is an ester of the higher fatty acid and glycerin, or a general formula such as glycerol borate traurate, glycerol borate stearate, and glycerol borate oleate. [I] (Wherein, X is H or COR, and R is an alkyl group or alkylene group having 11 to 21 carbon atoms), the higher fatty acid ester of glycerol borate and polyoxyethylene glycerol borate traurate, polyoxyethylene General formula of glycerol borate stearate, polyoxyethylene glycerol borate oleate, etc. [II] (In the formula, X and R are the same as in the case of the general formula [I], and l and m each usually represent an integer of 1 to 20).
The higher fatty acid ester of polyoxyethylene glycerol borate represented by Of the above-mentioned various higher fatty acid esters, sorbitan ester and glycerol borate higher fatty acid ester are usually preferred.

In the method of the present invention, a polyoxyethylene alkyl having an alkyl group having 7 to 10 carbon atoms such as polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol ether or the like and a polyoxyethylene group obtained by polycondensing 1 to 20 ethylene oxide as a dispersant. It is also possible to use phenol ethers.

Further, gelatin can be used as a dispersant in the method of the present invention.

In the present invention, the above-mentioned dispersants (d) can be used alone or in combination of two or more selected from the group of the dispersants (d). Examples of mixed use include a mixture of gelatin and a higher fatty acid metal salt such as gelatin / calcium-12-hydroxystearate (abbreviated as CHS), polyoxyethylene nonylphenol ether / polyoxyethylene such as calcium stearate. A method using a mixture of an alkylphenol ether and metal soap can be exemplified.

The water-swelling gelled crosslinked polymer produced by using the above-mentioned specific dispersant (d) used in the method of the present invention has a shape, a particle size, a particle size distribution, a surface smoothness and a transparency. Excellent in terms. That is, a spherical water-swelling gel-like crosslinked polymer having a shape close to a sphere, a large particle diameter of 1 to 20 mm and a uniform size, a smooth surface and high transparency is obtained.

When the dispersant of the present invention is used in the form of a mixture, the effect as a dispersant may be improved by adding polyalkylene glycol, if necessary. For example, when a mixture of polyoxyethylene alkylphenol ether and metal soap is used as a dispersant, it is preferable to add polypropylene glycol.

In the present invention, by using the above-mentioned specific dispersant (d) in the method of the present invention, it becomes possible for the first time to obtain a water-swelling gel-like crosslinked polymer having a spherical shape and a large particle size.

Non-Aqueous Dispersion Medium Specific examples of the non-aqueous dispersion medium (e) used in the method of the present invention include aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, mesitylene, and isopropylbenzene, and octane, nonane, and decane. Examples thereof include alkanes such as kerosene, cycloalkanes such as cyclohexane, methylcyclohexane, decalin, and the like. Of these non-aqueous dispersion media, benzene,
Preference is given to using toluene, xylene, decalin.

Ratio of use The mixture of the monomer components (a) and (b) used in the method of the present invention (monomer mixture) and water, the radical polymerization initiator (c), the dispersion medium (d) and the Non-aqueous dispersant
The usage ratio of (e) is as follows.

The use ratio of the monomer components (a) and (b) is as described above, and as the use ratio of water with respect to this monomer mixture,
It is optional as long as the monomer mixture forms an aqueous solution, but usually 200 to 30 per 100 parts by weight of the monomer mixture.
The amount is 00 parts by weight, preferably 300 to 1200 parts by weight.

The ratio of the radical polymerization initiator (c) used is the above (meth).
Usually 0.001 per 100 parts by mole of acrylic acid amides (a)
To 10 parts by mol, preferably 0.01 to 5 parts by mol.

The dispersant (d) is usually used in an amount of 0.0 with respect to 100 parts by weight of water.
It is in the range of 01 to 10 parts by weight, preferably 0.01 to 1 part by weight. When the use ratio of the dispersant is usually 0.001 part by weight or less, the effect of the dispersant is not exhibited, and even if the stirring speed is increased, the product has an amorphous broken state or a very small particle size. It is not preferable because it tends to occur.
On the other hand, if the amount is 10 parts by weight or more, the emulsion of oil and water is often violent, and the product tends to be an extremely small amount or a broken product, which is not preferable.

The proportion of the non-aqueous dispersion medium (e) used is usually 100 to 5000 parts by weight, preferably 150 to 1000 parts by weight, per 100 parts by weight of water. When the amount of the non-aqueous dispersion medium used is 150 parts by weight or less, not only the dispersibility of the aqueous monomer solution is deteriorated, but also it is difficult to remove the reaction heat generated during the polymerization and the dispersibility is poor, resulting in the formation of a heteromorph Is not preferable, and when it is 5000 parts by weight or more, the reaction heat can be removed and adjusted sufficiently, but the dispersibility of the aqueous monomer solution is poor and the particle size becomes non-uniform, and the productivity is low. It is not preferable.

Reaction In the method of the present invention, an aqueous solution containing the above monomers (a) and (b) and a radical polymerization initiator (c) is added to the dispersion medium (d).
The reaction is carried out by dispersing in the above-mentioned non-aqueous dispersion medium (e) in the presence of.

Generally, a polymerization method in which a monomer is strongly stirred and dispersed in a dispersion medium in which the monomer is not dissolved, and an initiator which is insoluble in the medium and is soluble in the monomer is added is known as suspension polymerization. In this method, for example, when a polymer such as styrene, methyl methacrylate, vinyl acetate, etc. is used and the polymer is dissolved in the monomer, the resulting polymer can be obtained in the form of small transparent particles. It is sometimes called (pearl) polymerization, and there are two kinds of methods, water in oil and oil in water, depending on whether the dispersion medium is oil or water. There are many known documents about the method of oil in water,
There are few reports about the method of water in oil.

The method of the present invention, the dispersion medium is a non-aqueous dispersion medium such as toluene (e)
And the monomer mixture dispersed therein is a water-soluble (meth) acrylamides (a) and a crosslinkable monomer (b), and the monomer mixture is a solution of droplets dissolved in water. In this state, it is dispersed in a non-aqueous dispersion medium to carry out polymerization. The produced polymer is obtained as a water-swollen gel-like cross-linked polymer that absorbs water and swells in a spherical shape. The method of the present invention belongs to the water-in-oil pearl polymerization method, but there is no known example of applying the (meth) acrylamides to the method as in the present invention, let alone adding such a monomer mixture to water. It is also not known to dissolve and disperse. In addition, the method of the present invention makes it possible to obtain a water-swelling gel-like crosslinked polymer having a large particle size and a spherical shape by using the above-mentioned specific dispersant (d). is there. Incidentally, a method for obtaining a water-swelling gel-like crosslinked polymer or a water-swellable crosslinked polymer as in the present invention by the pearl polymerization method has not been known so far, and other methods obtained by the pearl polymerization method are not known. All of the polymers have a small particle size of 1 mm or less, and no method for increasing the particle size has been known so far.

When the reaction is carried out by the method of the present invention, the reaction temperature is usually 25 to 100 ° C, preferably 60 to 95 ° C. When carrying out the reaction, there is a method in which the reaction is performed at a constant reaction temperature, or the temperature in the system is raised to a predetermined temperature over a certain time when the reaction is started, and then the temperature is maintained for a certain time. It can be illustrated. Here, it goes without saying that the temperature is kept within the range of the above reaction temperature. In the method of the present invention, it is preferable to employ a method of raising the temperature in the system after the start of the reaction, because the system maintains a uniformly dispersed state and a uniform reaction can be reproducibly obtained. The heating rate in this case is usually 0.1 to 10 ° C.
/ Min, preferably 0.5 to 3 ° C / min,
The reaction initiation temperature is usually in the range of 5 to 30 ° C., and usually room temperature is used. The predetermined temperature after the temperature rise is usually in the range of 60 to 95 ° C, preferably 80 to 90 ° C, and the reaction is further continued at the predetermined temperature for usually 10 minutes to 300 minutes, preferably 30 to 180 minutes. Here, the start time of the reaction is the time when the radical polymerization initiator is added to the system containing the monomer mixture, water, the dispersant (d), and the non-aqueous dispersion medium (e). The method of adding the radical polymerization initiator to the system is usually carried out by adding a solution of the radical polymerization initiator dissolved in an appropriate amount of water to the system. In this case, the amount of water is selected so that the total amount of water in the system after the addition is within the above range.

In the method of the present invention, the reaction rate is lowered when air is mixed into the system, so the reaction is carried out in the presence of an inert gas such as nitrogen.

The method of the invention is carried out with stirring. As a stirring method in this case, a known method can be adopted, and, for example, a method of mechanically rotating and stirring using stirring blades having various shapes can be shown. The preferable stirring speed in this case is slightly different depending on the type of stirring blade, the shape of the reactor, etc., and cannot be generally stated. However, when this is shown as the peripheral speed, it is usually 2,000 cm / min to 10 cm.
The particle size of the spherical water-swelling gel-like crosslinked polymer obtained can be controlled by appropriately selecting the stirring speed. That is, when the stirring speed is increased, a water-swelling gel-like crosslinked polymer having a small particle size and a spherical shape is obtained. Further, when the stirring speed is slowed, a water-swelling gel-like crosslinked polymer having a large particle size and a spherical shape or a spherical shape having a nonuniform particle size is usually obtained. At the above stirring speed, the peripheral speed is usually 2,000.
If it is less than 0 cm / min, a uniform dispersion state cannot be obtained,
The water-swelling gel-like cross-linked polymer that is produced is likely to become a large irregular shape, which is not preferable. Also usually 100,000 cm /
If it is more than min, the contents are emulsified and the product is apt to become ultrafine particles or minute broken pieces, which is not preferable.

After-treatment After the completion of the polymerization reaction, the reaction mixture is usually cooled to around room temperature, and then the spherical water-swelling gel-like crosslinked polymer is separated from the non-aqueous dispersion medium by a method such as filtration. The spherical water-swelling gel-like cross-linked polymer separated by filtration is usually washed with a low-boiling organic solvent such as hexane, or by a method such as steam stripping. Deposits such as a non-aqueous dispersion medium are removed from the coalescence. Then, the polymer is brought into contact with water to completely remove the unreacted monomer mixture, non-aqueous dispersion medium, and dispersant adhering thereto. The contacting method with water in this case is usually 5 to 10 for a spherical water-swelling gel-like crosslinked polymer.
It is carried out by contacting the polymer with 00 times the amount of water, preferably 50 to 400 times the amount of water, in batch or continuously. In this case, it is preferable to use running water while replacing it with fresh water. The contact time during washing with water is usually 1 to 10 hours, preferably 2 to 5 hours.

The spherical water-swelling gel-like crosslinked polymer from which impurities have been removed by the above-mentioned method can be used as it is for applications such as soil for hydroponic cultivation. Further, when the gelled crosslinked polymer is dried, a spherical water-swellable crosslinked polymer is obtained. The temperature during this drying is usually in the range of 25 to 100 ° C, preferably 60 to 90 ° C.

In the present invention, if necessary, the spherical water-swelling gel-like crosslinked polymer from which the above impurities have been removed or the spherical water-swellable crosslinked polymer obtained by drying the same is heat-treated in the presence of water. Then, the water-swelling property of the spherical polymer can be further enhanced. As the specific method of the heat treatment, the same method as that already proposed by the applicant in Japanese Patent Publication No. 4-25297 can be adopted. That is, the spherical water-swellable gel-like crosslinked polymer is usually dried in the range of 105 to 150 ° C, or the water-swellable crosslinked polymer is usually heat-treated in the presence of water in the range of 105 to 150 ° C. By performing the treatment, the water swelling property of the polymer can be greatly increased as compared with the case where the heat treatment is not performed.

The spherical water-swellable crosslinked polymer obtained by the method of the present invention can be easily converted into a spherical water-swellable gel-like crosslinked polymer by contacting with water. In the present invention, the term "spherical shape" is used to mean that the shape has a shape similar to a sphere such as a sphere, an ellipse, or a ball.

Regarding the particle size of the spherical water-swelling gel-like crosslinked polymer according to the present invention, the diameter of the spherical shape is,
Further, for an oval or ball-like shape, a spherical water-swelling gel-like crosslinked polymer having a minor axis diameter and a major axis diameter in the range of 1 to 20 mm can be obtained.

〔The invention's effect〕

When the method of the present invention is adopted, a spherical water-swelling gel-like crosslinked polymer excellent in water swelling property and transparency and having a uniform particle diameter of 1 to 20 mm or a dried spherical spherical water-swelling crosslinked polymer. The polymer can be efficiently produced.

〔Example〕

 Next, the present invention will be specifically described with reference to examples.

Example 1 50 equipped with a stir bar, thermometer, cooler and nitrogen blowing tube
Charge a 0 ml 4-neck separable flask with 200 ml of toluene,
Subsequently, 9.79 g of acrylamide, 0.21 g of N, N'-methylenebisacrylamide and 0.045 g of gelatin (dispersant) are dissolved in 85 g of water and charged. Within the diameter, at room temperature (25 ° C.), with stirring at 100 rpm, the water layer and the toluene layer are replaced with nitrogen for 15 minutes with nitrogen at a flow rate of 200 ml / min. Continued 0.01g
Ammonium persulfate was dissolved in 5 g of water and added, and the atmosphere was replaced with nitrogen for 5 minutes. After that, remove the nitrogen blowing tube, and adjust the stirring speed to 700 rpm (three blades including the squid-shaped blade, linear velocity of about 10,000 cm / min at a distance of about 4.5 cm from the center) under a nitrogen seal. Then, the content was heated to 80 ° C. and polymerized in an oil bath at a heating rate of 1.5 ° C./min. Under stirring at 700 rpm, 80 ℃ / 15min, 400 more
Polymerization was completed for 60 minutes with stirring at rpm. The obtained spherical (and partly spherical gel-containing gel) water-swollen gel-like cross-linked polymer is cooled to room temperature and then separated by filtration to separate from the toluene layer, followed by steam stripping. ,
By further washing with running water, toluene, gelatin and monomer components remaining in the granules were removed. The water-swollen gelled crosslinked polymer after washing was dried in a hot air dryer at 60 to 80 ° C. The resulting water-swellable crosslinked polymer had the following physical properties.

(1) The density (24 ° C.) of the polymer was 1,260 (g / cm ³ ).

(2) When immersed in water at 24 ° C., it absorbs water, and becomes a transparent (including 1 part of air) water-swelling gel-like cross-linked polymer containing 3 to 7 mm spherical or 1 part spherical particles. The degree of swelling at this time is
It was 20 times.

The density and swelling degree of the dried crosslinked polymer are values measured by the following methods.

Density: A constant weight (Wg) of dried polymer was collected in a 25 ml pycnometer. Then, the pycnometer containing the polymer was placed in a constant temperature bath at 24 ° C. and filled with toluene at 24 ° C.
The toluene volume (V) was calculated from the weight of toluene required for this, and calculated by the following formula.

Swelling degree: A constant weight (W ₁ g) of the dried polymer product was collected,
The polymer was sufficiently swollen by being immersed in water at 24 degrees for 24 hours.
After that, excess water was removed and the weight (W ₂ g) of the swellable gel-like substance was measured and calculated by the following formula.

The water-swollen gel polymer obtained shows the same swelling ratio as the polymer before drying, and can be used as an artificial soil or a soil modifier for gardening in the same manner as the gel polymer re-absorbed after drying. Atsuta In addition, the swelling ratio of the water-swelling gel-like crosslinked polymer is increased 3 to 100 times by further heat treatment in the presence of water according to the formulation previously filed by the present inventors (Japanese Patent Publication No. 4-25297). It is also possible to adjust.

Example 2 A spherical water-swelling gel-like crosslinked polymer was used in the same manner as in Example 1 except that 0.09 g of calcium hydroxystearate (CHS) was used as a dispersant instead of gelatin in a toluene dispersion medium. Manufactured. The CHS dispersant was removed when the gelled crosslinked polymer was washed with water, and the resulting water-swollen gelled crosslinked polymer was a spherical gel having a diameter of 4 to 7 mm and had few bubbles and was transparent, and also in terms of surface smoothness. Was excellent. The density (24 ° C.) of the polymer obtained by drying the water-swelling gel-like cross-linked polymer was 1.277 (g / cm ³ ), and when this polymer was immersed in water, transparent water having a diameter of 4 to 7 mm was obtained. It became a swollen gel-like crosslinked product, and the swelling ratio at this time was 21 times.

Examples 3 to 10 A spherical water-swelling gel-like crosslinked polymer was produced in the same manner as in Example 1 except that the dispersant shown in Table 1 was used in place of gelatin as the dispersant. In the table, the water-soluble dispersant was dissolved in water and the oil-soluble dispersant or oil-swellable dispersant was dissolved or dispersed in toluene. Table 1 shows the physical properties of the spherical water-swelling gel-like crosslinked polymer obtained by changing the type of various dispersants. A typical example of the obtained water-swelling gel-like material is shown in FIG.

Comparative Examples 1 to 6 In the same manner as in Example 1 except that the dispersant was not used or a cationic or anionic surfactant which is usually used as an emulsifier as shown in Table 2 was used as the dispersant. An attempt was made to produce a water-swelling gel-like cross-linked polymer having a shape.
The results of investigating the kind of the dispersant and the shape of the product are shown in Table 2. In any case, it seems that the proper dispersion state of water / oil before polymerization was obtained by adjusting the amount of the dispersant and the stirring speed. However, when the polymerization was started, the emulsification or conversely the appropriate dispersion state was broken. For this reason, the product contained a few percent of spheres, but most of them were broken or strip-shaped.

[Brief description of drawings]

FIG. 1 and FIG. 2 are micrographs (magnifications of 1 × and 5 ×, respectively) showing the particle structure of the spherical water-swelling gel-like crosslinked polymer obtained in Example 2.

Claims (1)

[Claims] 1. An aqueous solution containing a (meth) acrylamide (a), a crosslinkable monomer (b) and a radical polymerization initiator (c) is treated with a higher fatty acid salt, a higher fatty acid amide, a higher fatty acid ester, polyoxy A spherical cross-linked polymer having a particle diameter of 1 to 20 mm, which is obtained by reacting while dispersing in a non-aqueous dispersion medium (e) in the presence of a dispersant (d) selected from the group consisting of ethylene alkylphenol ether and gelatin. Production method.