KR100905853B1 - Production method of water-absorbent resin, water-absorbent resin, and usage of water-absorbent resin - Google Patents

Abstract

The present invention relates to a method for producing an absorbent resin, an absorbent resin, and a use thereof, which can prevent adhesion of a hydrous gel polymer and can perform drying smoothly.

By still-polymerizing the ethylenically unsaturated monomer containing acrylic acid and / or acrylate, and drying the hexahedral hydrogel polymer mainly composed of hexahedral and smooth surfaces obtained by cleaving the hydrogel polymer after polymerization. In this case, it is possible to obtain a water-absorbent resin that is non-aggregated and smoothly dried. By coating the anti-sticking agent on at least a part of the surface of the hydrogel polymer before, simultaneously with, and / or after cutting the hydrogel polymer, the non-agglomeration of the water absorbent resin is improved.

Absorbent resin, water-containing gel polymer, rotary sorter

Description

Production method of absorbent resin, absorbent resin, and use thereof {PRODUCTION METHOD OF WATER-ABSORBENT RESIN, WATER-ABSORBENT RESIN, AND USAGE OF WATER-ABSORBENT RESIN}

1 is a longitudinal cross-sectional view showing the configuration of a defoaming machine.

2 is a longitudinal sectional view showing the configuration of a degassing membrane module.

3 is a longitudinal sectional view showing a configuration of a cutter according to the present embodiment.

4 is a longitudinal sectional view showing the coated scraper.

FIG. 5: is explanatory drawing which shows the structure which saw the longitudinal cutting blade (rolling cutter) 1 and 2 from the top.

6 is an explanatory view of the engaging portion of the longitudinal cutting blades (rolling cutters) 1, 2.

FIG. 7 is an enlarged explanatory view of the engaging portion shown in FIG. 6. FIG.

8 is a side view showing the configuration of the rotary sorting machine according to the present embodiment.

9 is a cross-sectional view illustrating a configuration of the first sorting unit illustrated in FIG. 8.

10 is a cross-sectional view illustrating a configuration in which the second sorting unit illustrated in FIG. 8 is one layer.

FIG. 11 is a cross-sectional view illustrating a configuration in which the second sorting unit illustrated in FIG. 8 is two layers. FIG.

FIG. 12 is a schematic perspective view showing the configuration of the second sorting unit shown in FIG. 8. FIG.

Fig. 13 is a sectional view showing the configuration of a vibration plane type sorter according to the present embodiment.

It is a typical perspective view which shows the structure of the 2nd sorting part shown in FIG.

It is a schematic diagram of the apparatus which measures the amount of dust of water absorbing resin.

[Patent Document 1] Japanese Patent Application Laid-Open No. 8-92307 (published April 9, 1996)

[Patent Document 2] Japanese Patent Publication No. 61-110510 (published May 28, 1986)

[Patent Document 3] Japanese Patent Application Laid-Open No. 11-349687 (published December 21, 1999)

[Patent Document 4] US Patent No. 4973632

[Patent Document 5] U.S. Patent No. 5998553

[Patent Document 6] Japanese Patent Publication No. 63-7203 (February 16, 1988 announcement)

[Patent Document 7] US Patent No. 2004-0068057

[Patent Document 8] Japanese Patent Publication No. Hei 7-98847 (October 25, 1995)

[Patent Document 9] Japanese Patent Application Laid-Open No. 4-106108 (published April 8, 1992)

[Patent Document 10] US Patent No. 5229488

[Patent Document 11] Japanese Patent Publication Hei 5-40780 (June 21, 1993)

The present invention relates to a method for producing an absorbent resin, an absorbent resin, and a use thereof, which can prevent adhesion of a hydrous gel polymer and can perform drying smoothly.

It is well known that a water-containing gel polymer can be obtained as an absorbent polymer by aqueous solution polymerization of a water-soluble ethylenically unsaturated monomer (for example, patent document 1). This hydrous gel polymer is obtained as a gel-type substance having a semi-solid and excellent elasticity, and is used as an absorbent resin, that is, an absorbent by cutting and drying it.

When the hydrogel is cut, if it is simply cut and no action is taken, the cleaved hydrogel polymers adhere to each other. For example, when the hydrogel is mechanically cut, the hydrogel cannot be cut continuously and the work efficiency is lowered. Therefore, in order to prevent the said adhesion, surfactant, a polymer polyhydric alcohol, etc. are used normally (for example, patent document 2, 3).

On the other hand, unreacted monomers (hereinafter, referred to as "remaining monomers") in the hydrogel are impurities in the polymer, and may be less odor or sanitary problem. Conventionally, as a method of reducing a residual monomer, the method of increasing the addition amount of a radical polymerization initiator, the method of dividingly adding a radical polymerization initiator, etc. are known (patent documents 4-10).

Further, Patent Document 11 discloses that the absorption rate of the absorbent material can be improved by spraying a polyvalent metal salt aqueous solution onto the dry powder type hydrophilic polymer particles having a water content of 20% by mass or less.

However, the above conventional technique has a problem in that adhesion of the hydrogel polymers cannot be sufficiently prevented.

Further, even in the case of Patent Documents 6 and 7, the detailed cause is not clear, but due to the heat treatment in the subsequent step, a problem arises that off-flavor that is thought to be derived from a component in which the added reducing substance and impurities derived from the raw material are combined. There is. Moreover, also in the case of the said patent document 8, although the amount of the monomer which remain | survives surely reduces, there exists a problem that the variation in the amount of the residual monomer of an absorbent is large, and that the amount of the residual monomer was not reduced to a desired level, or a spec out product appears.

Moreover, when the amount of residual monomers is reduced using the technique of the said patent documents 4 and 5, the water absorbing resin obtained may be colored and there exists a problem that a commodity value falls. In addition, in order to reduce the amount of residual monomers, various stringent reaction conditions are required, so that the physical properties may be deteriorated due to deterioration of the polymer, and the reduction to the desired residual monomer level and absorption magnification and pressure under no pressure are required. There is also a problem that it is difficult to make both maintenance and improvement of absorption characteristics such as absorption magnification under the following conditions.

That is, although patent document 4 has mentioned polyethyleneglycol and surfactant as an adhesive agent as an example, it does not describe specifically how to process a hydrous gel type polymer using these. In addition, in the technique described in Patent Literature 5, a surfactant, a polymer polyhydric alcohol, and the like are used to prevent adhesion of the hydrous gel polymers, but since the particle size distribution of the hydrogel polymer is wide and the shape of the hydrogel polymer is not homogeneous, It is easy to clump together.

In addition, as described in Patent Document 11, a method of spraying a polyvalent metal salt solution onto dry powder polymer particles is already known, but this technique is not intended to prevent adhesion between the hydrogel polymers, and a polyvalent metal salt solution There is no research on the technique of sufficiently preventing the adhesion of the hydrogel polymers by coating with a coating or the like.

The present invention has been made in view of the above problems. The object is to provide a method for producing an absorbent resin, an absorbent resin, and the use thereof, which can prevent adhesion of the hydrogel polymer and can perform drying smoothly, and preferably absorbent having reduced content of the remaining monomers. It is related with the water absorbing resin which reduced the manufacturing method of resin, content of a residual monomer, and its use.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in view of the said subject, as a result, at least a part of the surface of the hydrous gel-type polymer which has a polyhedron shape whose shape is a square shape and the surface is smooth is classified as a polyvalent metal salt, polyhydric alcohol, or surfactant. By coating by a specific method using an anti-adhesion agent containing at least one kind of the compound to be formed, it was found that the workability at the time of cutting is improved, and since it becomes non-aggregated even if it is dried, favorable drying is possible. In addition, the inventors have found that the residual monomer can be reduced by drying the hydrogel polymer having a specific mass average particle diameter, and thus, the present invention has been completed.

That is, the manufacturing method of the water absorbing resin which concerns on this invention,

(1) An ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less (excluding a crosslinking agent) of acrylic acid and / or acrylate is fixed in a sheet form, and the water content is 40 mass% or more and 70 mass% A polymerization step of obtaining a hydrous gel polymer having the following content,

(2) A cutting step of cutting the hydrous gel polymer so that particles having a tetrahedral to 12-hedron shape having a mass average particle diameter of 3 mm or more and 10 mm or less are 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer. After drying the water-containing gel polymer to have a water content of 5% by mass or more and 60% by mass or less, particles having a tetrahedron or more tetrahedron having a mass average particle diameter of 2 mm or more and 10 mm or less are added to the mass of the water-containing gel polymer. Cutting step of cutting so as to be 50% by mass or more and 100% by mass or less;

(3) Before the cleavage of the hydrous gel polymer, before and at the same time, and / or after cleavage, the hydrogel polymer is used as an anti-adhesion agent comprising at least one kind of a compound classified as a polyvalent metal salt, a polyalcohol or a surfactant. A coating step of covering at least a part of the surface;

(4) a drying step of drying the coated hydrogel polymer.

According to the said structure, the hydrous gel-type polymer containing 50 mass% or more and 100 mass% or less of the tetrahedron to 12-hedron shape which is a square shape and the surface is smooth is coat | covered with an anti-adhesive agent, The anti-sticking agent acts as a release agent between the hydrogel polymers. Therefore, adhesion of the hydrous gel polymer at the time of cutting and / or after cutting can be prevented, and drying can be performed smoothly.

Moreover, since the water content of the hydrogel polymer is 40 mass% or more and 70 mass% or less, and the mass mean particle size is 3 mm or more and 10 mm or less and a large particle size, the remaining monomers can be sufficiently reacted in the drying step. Therefore, the water-absorbent resin can be obtained which has little content of the residual monomer and which does not affect the problems of hygiene and odor.

In addition, the cutter according to the present invention is a cutter for cutting a sheet-like hydrogel polymer, at least one or more longitudinal cutting blade for longitudinally cutting the hydrogel gel polymer, and at least one or more for cutting the hydrogel gel polymer horizontally And at least one spraying and / or spreading means for spraying and / or spraying the transverse cutting blade and the fixed blade and the anti-sticking agent onto the longitudinal cutting blade, the transverse cutting blade, the fixed blade and / or the hydrous gel polymer. It features.

According to the above configuration, it is possible to efficiently spray and / or spray the anti-adhesive agent to the hydrous gel polymer which has become a polyhedron shape due to longitudinal cutting or transverse cutting. Therefore, the adhesion of the hydrogel polymers can be reduced. Therefore, it can use suitably for manufacture of the water-absorbing resin of the non-aggregated state in which particle shape was uniform, and it can use preferably for manufacture of the water-absorbent resin with few content of a residual monomer.

In addition, the water-absorbent resin according to the present invention polymerizes an ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less of acrylic acid and / or acrylate, and the particles having a tetrahedral or more tetrahedral shape or less are hydrous gel polymers. Absorbent resin obtained by drying the hydrogel polymer cut into 50 mass% or more and 100 mass% or less with respect to the mass, wherein the mass mean particle size is 2 mm or more and 10 mm or less, and the logarithmic standard deviation value of the particle size distribution is 0 or more and 0.25 or less. It features.

The said water absorbing resin is obtained by drying the hydrous gel type polymer with the uniform particle size. Therefore, in the manufacturing process, adhesion of the hydrogel polymers is sufficiently prevented, and a sufficiently dried absorbent resin can be obtained.

Moreover, the sorter which concerns on this invention is a sorter which sorts the absorbent resin after drying, It is characterized by including a gas injection mechanism.

By this sorting machine, since large releasing material and small releasing material of the water absorbing resin which completed drying can be removed, the water absorbing resin of desired mass average particle diameter can be obtained. Thereby, since the mass average particle diameter of the obtained water absorbing resin is uniform, the display effect of a water absorbing resin can be improved.

In addition, the water-retaining agent for plant growth according to the present invention is characterized in that it comprises an absorbent resin produced by the method according to the present invention and / or an absorbent resin according to the present invention. Since the water absorbent resin according to the present invention has few residual monomers that lower the physical properties of the water absorbent resin, it does not affect the problems of hygiene and odor. The plant growth repair agent according to the present invention can introduce a sufficient amount of water, and once absorbed, can reduce the trouble of watering the plant for a long time and has an excellent display effect.

The artificial ice for display according to the present invention is further characterized by comprising an absorbent resin produced by the method according to the present invention and / or an absorbent resin according to the present invention. Since the water absorbent resin according to the present invention has few residual monomers that lower the physical properties of the water absorbent resin, it does not affect the problems of hygiene and odor. The artificial ice for the display according to the present invention may introduce a sufficient amount of water, and once absorbed, maintains the appearance similar to the real ice for a long time, thereby maintaining the display effect.

Still other objects, features, and advantages of the present invention will be fully understood from the following description. Further advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

EMBODIMENT OF THE INVENTION Although embodiment of this invention is described as follows, this invention is not limited to this. Hereinafter, the manufacturing method of the water absorbing resin which concerns on this invention is demonstrated in detail.

(1.Method for producing absorbent resin)

In one embodiment, the manufacturing method of the water absorbing resin which concerns on this invention,

(1) A hydrogel polymer having a water content of 40% by mass or more and 70% by mass or less by polymerizing an ethylenically unsaturated monomer containing acrylic acid and / or acrylate in an amount of 30 mol% or more and 100 mol% or less (excluding the crosslinking agent) in a sheet form. Polymerization process to obtain

(2) a cutting step of cutting the hydrous gel polymer so that particles having a tetrahedral to 12-hedron shape having a mass average particle diameter of 3 mm or more and 10 mm or less are 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer; Or after drying the said hydrogel type | mold polymer so that water content may be 5 mass% or more and 60 mass% or less, the particle | grains of the tetrahedron to 12-hedron shape whose mass mean particle diameter is 2 mm or more and 10 mm or less are 50 with respect to the mass of a water-containing gel polymer. A cutting step of cutting so that the mass is at least 100 mass%,

(3) the hydrogel polymer as an anti-adhesion agent comprising at least one kind of a compound classified into a polyvalent metal salt, a polyhydric alcohol, or a surfactant before, simultaneously with, and / or after cleaving the hydrogel polymer, A coating step of covering at least a part of the surface;

(4) a drying step of drying the coated hydrogel polymer.

The hydrogel polymer polymerizes the ethylenically unsaturated monomer, preferably in the presence of trace amounts of crosslinking agent, and covers at least a portion of the surface with an anti-adhesive agent before, simultaneously with and / or after cleaving the polymer. It is obtained by. In addition, in this specification, the term "functional gel polymer" shall include both a hydrogel polymer which is not crosslinked between hydrogel polymers and a hydrogel gel crosslinked polymer which is crosslinked between hydrogel polymers. In addition, in this specification, "mass" and "mass%" are treated synonymously with "weight" and "weight%", respectively.

The ethylenically unsaturated monomer used as a raw material of the hydrous gel polymer is a monomer having water solubility, and specific examples thereof include (meth) acrylic acid, β-acryloyloxypropionic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, Itaconic acid, cinnamic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, Acid group-containing monomers such as vinylphosphonic acid, 2- (meth) acryloyloxyethyl phosphoric acid and (meth) acryloxyalkanesulfonic acid, and alkali metal salts, alkaline earth metal salts, ammonium salts and alkylamine salts thereof; Dialkylaminoalkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylamide And these quaternized compounds (e.g., reactants with alkylhydrides, reactants with dialkylsulfuric acid, etc.); Dialkylaminohydroxyalkyl (meth) acrylates and these quaternized compounds; N-alkylvinylpyridinium halides; Hydroxyalkyl (meth) acrylates such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl (meth) acrylate; Acrylamide, methacrylamide, N-ethyl (meth) acrylamide, N-n-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide; Alkoxy polyethylene glycol (meth) acrylates such as methoxy polyethylene glycol (meth) acrylate and polyethylene glycol mono (meth) acrylates; Vinylpyridine, N-vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine; N-vinylacetamide; Etc. can be mentioned. One type of these ethylenically unsaturated monomers may be used, or may mix and use two or more types suitably.

Among the ethylenically unsaturated monomers exemplified above, 30 mol% or more and 100 mol% or less, preferably 50 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less of acrylic acid and / or acrylates. It is preferable to contain. If it is less than 30 mol%, the water absorption performance and safety of the hydrous gel obtained may fall further, and also the polymerization reactivity may fall. In addition, the versatility may be lowered and the economics may be lowered. Here, the acrylate refers to an alkali metal salt, alkaline earth metal salt, ammonium salt, hydroxyammonium salt, amine salt or alkylamine salt of acrylic acid.

Of the water-soluble salts exemplified above, sodium salts and potassium salts are particularly preferred. These acrylate monomers may be used alone or in combination of two or more. In addition, the average molecular weight (polymerization degree) of water absorbing resin is not specifically limited.

Said hydrous gel polymer can be obtained by polymerizing the monomer composition containing the said ethylenically unsaturated monomer as a main component, preferably in presence of a trace amount of crosslinking agent. Moreover, the said monomer composition may contain the other monomer (copolymerizable monomer) copolymerizable with the said ethylenically unsaturated monomer so that the hydrophilicity of the hydrous gel type polymer obtained may not be impaired.

Specifically as said copolymerizable monomer, For example, (meth) acrylic acid ester, such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate; Hydrophobic monomers such as vinyl acetate and vinyl propionate; Etc. can be mentioned. These copolymerizable monomers may be used alone or in combination of two or more thereof.

Moreover, as a crosslinking agent used when superposing | polymerizing the said monomer component, For example, The compound which contains a plurality of vinyl groups in a molecule | numerator; The compound etc. which contain two or more functional groups which can react with a carboxyl group or a sulfonic acid group are mentioned in a molecule | numerator. These crosslinking agents may be used independently and may use two or more types together.

As a compound containing two or more vinyl groups in a molecule | numerator, specifically, N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth), for example ) Acrylate, trimetholpropane tri (meth) acrylate, trimetholpropanedi (meth) acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimetholpropane tree ( Meta) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, NN-diallylacrylamide, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallyl Amine, diallyloxy acetic acid, bis (N-vinyl carboxylic acid amide), tetraallyloxy ethane, etc. are mentioned.

Examples of the compound containing a plurality of functional groups capable of reacting with a carboxyl group or a sulfonic acid group in a molecule include (poly) ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polypropylene glycol, (poly) glycerine, 2-butene-1,4-diol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Hexanediol, 1,2-cyclohexanedimethanol, 1,2-cyclohexanol, trimetholpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethyleneoxypropylene block copolymer, pentaerythritol, sorbitol, etc. Polyhydric alcohol compounds; Epoxy compounds such as (poly) ethylene glycol diglycidyl ether, (poly) glycerol polyglycidyl ether, diglycerol polyglycidyl ether, (poly) propylene glycol diglycidyl ether, glycidol; Polyvalent amine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyamide polyamine, and polyethyleneimine, and condensates of these polyvalent amines with haloepoxy compounds; Polyhydric isocyanate compounds such as 2,4-trilene diisocyanate and hexamethylene diisocyanate; Polyhydric oxazoline compounds such as 1,2-ethylenebisoxazoline; silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltrimethoxysilane; 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl -1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3 -Dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, 1,3-dioxopan-2- Alkylene carbonate compounds such as on; Haloepoxy compounds such as epichlorohydrin; And hydroxides and chlorides such as zinc, calcium, magnesium, aluminum, iron, and zirconium.

Although it does not specifically limit as the usage-amount of the said crosslinking agent, It is preferable to exist in 0.0001 mol% or more and 10 mol% or less with respect to the said monomer component, and it is more preferable to exist in 0.001 mol% or more and 1 mol% or less. In this invention, aqueous solution polymerization is mentioned as a method of superposing | polymerizing said monomer component, As a specific method, the stationary polymerization on a bat, a belt, or polymerization in kneader is mentioned. Among these, the method of stationary polymerization on a movable endless belt is preferable because the following cutting process can be performed continuously.

Although the said stationary polymerization does not have a limitation of the thickness of a polymeric gel sheet, It is preferable to consist of sheet thickness of 3 mm or more and 10 mm or less. That is, it is preferable that the thickness of the sheet-like hydrous gel polymer produced by the polymerization step is 3 mm or more and 10 mm or less. By performing the stationary polymerization to the sheet thickness, it is possible to effectively reduce the residual monomer in the drying step.

In other words, when the sheet-shaped hydrogel polymer is longitudinally cut and transversely cut, a hexagonal gel mainly composed of a rectangular shape and having a smooth surface is produced, and a sheet-shaped hydrogel having a thickness of 3 mm or more and 10 mm or less is produced. By longitudinally cutting and cross-cutting the polymer, a hexagonal gel having a mass average particle diameter of 3 mm or more and 10 mm or less is formed mainly of a square shape with a smooth surface. As described later, the hydrous gel polymer having a mass average particle size of 3 mm or more and 10 mm or less is effective for reducing the residual monomer content in the water absorbent resin after drying. Therefore, it is preferable that the said stationary polymerization consists of sheet thickness of 3 mm or more and 10 mm or less.

In addition, when polymerizing the said ethylenically unsaturated monomer in aqueous solution, either system of continuous polymerization or batch polymerization may be employ | adopted, and also it can carry out under pressure of either normal pressure, reduced pressure, or pressurization. In addition, the polymerization reaction may be carried out in an air atmosphere, preferably under a stream of inert gas such as nitrogen, helium, argon, carbon dioxide and the like.

In the polymerization reaction, at the start of the polymerization, for example, a polymerization initiator or activating energy rays such as radiation, electron beams, ultraviolet rays, and electron beams can be used.

Although it does not specifically limit as said polymerization initiator, A thermal decomposition type initiator and a photolysis type initiator are used, The usage-amount is 0.001-5 mol%, Preferably it is 0.01-0.5 mol%. As a thermal decomposition initiator, Persulfates, such as sodium persulfate, potassium persulfate, ammonium persulfate; Peroxides such as hydrogen peroxide, t-butyl peroxide and methyl ethyl ketone peroxide; Azonitrile compound, Azoamidine compound, Cyclic azoamidine compound, Azoamide compound, Alkyl azo compound, 2,2'- azobis (2-amidinopropane) dihydrochloride, 2,2'- azobis {2 Azo compounds, such as-(2-imidazolin-2-yl) propane] dihydrochloride, are mentioned.

As a photoinitiator, a benzoin derivative, a benzyl derivative, an acetophenone derivative, a benzophenone derivative, an azo compound, etc. are mentioned. These polymerization initiators may be used alone or in combination as appropriate. In consideration of the remaining monomer reduction ability, it is preferable to use a thermal decomposition initiator and a photolysis initiator together. In addition, when using a peroxide as a polymerization initiator, you may perform redox polymerization by using together reducing agents, such as a sulfite, a bisulfite, and L-ascorbic acid, for example.

In order to start the said polymerization reaction stably, it is preferable to make the dissolved oxygen amount in the said ethylenic unsaturated monomer aqueous solution constant, and in order to start superposition | polymerization more smoothly, it is preferable to reduce the dissolved oxygen amount in the said aqueous solution. The preferred range of dissolved oxygen is 8 mg / L or less, more preferably 6 mg / L or less, particularly preferably 2 mg / L or less.

When the polymerization reaction is started in a state where bubbles remain in the aqueous solution by degassing, bubbles remain in the sheet, which is not preferable because it impairs the display effect of the water absorbent resin. In this case, in order not to impair the display effect of the absorbent polymer, it is necessary to perform degassing at the same time as degassing.

As a method of removing residual oxygen in the aqueous solution in an ethylenically unsaturated monomer, the inert gas is injected, the vacuum degassing method, the film removal method, the reducing agent addition method, etc. are mentioned, for example. These methods are described below.

(a.injection of inert gas)

(I) a method of injecting an inert gas into a piping of an aqueous solution of ethylenically unsaturated monomer to the polymerization apparatus, or (II) a method of bubbling with an inert gas in a liquid tank containing an ethylenically unsaturated monomer. In either method, it is necessary to start the polymerization after removing the injected inert gas and bubbles of precipitated oxygen.

As a method of removing bubbles, (I) when inert gas is injected into a pipe of an aqueous solution of ethylenically unsaturated monomer to the polymerization apparatus, for example, a method of separating bubbles and liquid using swirl flow, and ethylenically unsaturated The method of putting a monomer aqueous solution into a degassing tank once, and leaving it until a bubble is removed is mentioned. As a method of using a swirl flow, Quick Tron which is a Shin-Nippon Seika Yugaku Co., Ltd. product can be used, for example.

The defoaming machine represented by the quick Tron is described below using FIG. 1 as follows. The defoaming machine 400 is cylindrical and provided with a conical cyclone chamber 30 inside. The bubble removing tube 31 is further provided in the center of the cyclone chamber 30. Moreover, the inlet hole 28 and the pre-swirl flow chamber 29 which introduce | transduce the liquid containing foam are provided. In addition, an outlet hole 32 is provided at an upper portion of the degassing machine 400.

First, the fluid introduced in the direction of arrow F is introduced into the cyclone chamber 30 from the inlet hole 28. Then, the fluid which removed the bubble in the cyclone chamber 30 is discharged | emitted from the outlet hole 32 in the direction of arrow H through many small holes.

On the other hand, bubbles with a small amount of fluid are collected in the center of the cyclone chamber 30, and passes through the bubble removing tube 31 to be discharged in the G direction.

Moreover, when bubbling an inert gas in the liquid tank containing the aqueous solution of (II) ethylenic unsaturated monomer, the method of leaving to stand until a bubble is removed is mentioned.

(b. degassing)

It is a method of reducing the dissolved oxygen in the said ethylenically unsaturated monomer aqueous solution by depressurizing the aqueous solution of an ethylenically unsaturated monomer. In addition to the method of depressurizing the aqueous solution of an ethylenically unsaturated monomer, the method of using a degassing pump, etc. are mentioned. As a method of using a degassing pump, the degassing pump ASP-0310 and ASP-0510 by the Yokoda Seisakusho company can be used, for example.

(c. film removal)

It is one of the vacuum degassing methods, and when the aqueous solution of an ethylenically unsaturated monomer passes inside a degassing membrane module, by making the outer side of a degassing membrane module into pressure reduction, the dissolved oxygen in an ethylenic unsaturated monomer aqueous solution is made to the outer side of a degassing membrane module. It is a way to discharge.

As the degassing membrane, a porous membrane or a separation membrane can be used. For example, a silicone resin non-porous membrane NAGASEP M40-A, M40-B, M-60-B, M80-B, which is a separation membrane manufactured by Nagayanagi Kogyo Co., Ltd. As the non-porous membrane of Mitsubishi Rayon Engineering Co., Ltd., degassing membrane modules MHF0504MBFT, MHF1704, MHF3504, MHF304EED, MGF304KMD, MHF0498P and the like can be used.

2 shows an outline of the degassing membrane module. The degassing membrane module 500 is provided with a plurality of degassing membranes 35 inside the cover 36. A vacuum pump is provided from the side surface of the degassing membrane 35 via the pipe 34, and is configured to reduce the pressure in the direction of the arrow K. As shown in FIG. First, a fluid containing dissolved gas such as dissolved oxygen is introduced into the degassing membrane module 500 in the direction of arrow I. Thereafter, the dissolved gas in the fluid passes through the degassing membrane 35 in the direction of the arrow K, and the degassed fluid is discharged from the direction of the arrow J.

(d.Reducing agent addition method)

It is a method of chemically degassing by adding hydrazine, sodium sulfite, or sodium bisulfite in an ethylenic unsaturated monomer aqueous solution.

In addition to degassing and degassing by ultrasonic waves, as well as each of the above methods, or alone.

In the polymerization reaction, the mixing of bubbles in the gel sheet is not preferable because it impairs the display effect of the absorbent resin. For this reason, for example, (I) degassing and degassing an aqueous solution of ethylenically unsaturated monomers, (II) suppressing heat generation during polymerization, for example, suddenly boiling Dolby phenomenon of an aqueous solution of ethylenically unsaturated monomers In order to avoid, it is preferable to carry out the polymerization by setting the temperature of the aqueous solution of ethylenically unsaturated monomers to 30 ° C or lower, preferably 25 ° C or lower, more preferably 20 ° C or lower. (III) It is preferable to start a polymerization by the polymerization reaction using an ultraviolet-ray using a photolysis initiator.

Moreover, the highest reaching temperature of the hydrous gel polymer in polymerization is 60 ° C or more and 100 ° C or less, preferably 70 ° C or more and 90 ° C or less, more preferably 80 ° C or more and 90 ° C or less. It is not preferable to exceed 100 ° C because the Dolby phenomenon of the ethylenically unsaturated monomer aqueous solution occurs, and below 80 ° C, the polymerization time becomes long and the productivity decreases.

In addition, as the accumulated light quantity of ultraviolet rays required for the polymerization reaction, and is preferably 500mJ / cm ² over 5000 mJ / cm ² or less, more preferably 600mJ / cm ² or more 4000mJ / cm ² or less. If the accumulated light amount is less than 500 mJ / cm ² , it is not preferable because more photolysis initiator is required. In addition, when the accumulated light amount exceeds 5000 mJ / cm ² , a polymerization reaction occurs rapidly, and there is a fear that a dolby phenomenon in which an aqueous solution of an ethylenically unsaturated monomer suddenly boils may occur due to the exotherm at that time. In addition, since the gel sheet is irradiated with more energy than necessary, the hydrogel polymer is inferior or decomposed, which is not preferable.

UV lamps for generating ultraviolet rays include a black light mercury lamp, a metal halide lamp, a high pressure mercury lamp, and the like. Any of these lamps may be used, or these lamps may be used in combination. Especially, it is preferable to adjust a accumulated light quantity using a metal halide lamp and a black light mercury lamp together.

When polymerizing the said monomer component in presence of a crosslinking agent, it is preferable to use water as a solvent. That is, it is preferable to make the said monomer component and a crosslinking agent into aqueous solution. This is to improve the water absorption performance of the obtained water absorbent resin.

As for the density | concentration of the monomer component in the said aqueous solution (henceforth a monomer aqueous solution), the inside of the range of 30 mass% or more and 60 mass% or less is more preferable. When the density | concentration of a monomer component is less than 30 mass%, there exists a possibility that the water-soluble component amount of the water absorbing resin obtained may increase. On the other hand, when the concentration of a monomer component exceeds 60 mass%, it may become difficult to control reaction concentration. In this manner, a water-containing gel polymer having a water content of 40% by mass or more and 70% by mass or less can be obtained.

Moreover, as a solvent of the monomer aqueous solution, water and the organic solvent which melt | dissolve in water can also be used together. Specifically as this organic solvent, methyl alcohol, ethyl alcohol, acetone, dimethyl sulfoxide, ethylene glycol monomethyl ether, glycerin, (poly) ethylene glycol, (poly) propylene glycol, alkylene carbonate, etc. are mentioned, for example. have. These organic solvents may be used independently and may use 2 or more types together.

In the cutting step, the hydrogel polymer polymerized into a sheet shape is longitudinally cut and transversely cut, whereby particles having a tetrahedron shape or more and a dodecahedron shape having a rectangular shape and a smooth surface are formed on the mass of the hydrogel polymer. It cut | disconnects so that it may become 50 mass% or more and 100 mass% with respect to it, Preferably the hexagonal particle which consists of a surface with a square shape and the surface is smooth is 50 mass% or more and 100 mass% with respect to the mass of the said hydrogel type polymer. Below, Preferably it is 80 mass% or more and 100 mass% or less, More preferably, it is 90 mass% or more and 100 mass% or less, Especially preferably, it cut | disconnects so that it may become 95 mass% or more and 100 mass% or less.

In the obtained hydrogel polymer, when the hexagonal particles having a square shape and a smooth surface are 50% by mass or less with respect to the mass of the hydrogel polymer, the hydrogel gel polymer is uneven. Since the display performance at the time of swelling the water absorbing resin obtained after drying with an aqueous liquid may fall, it is not preferable.

When the water-containing gel polymer molded into a sheet shape is longitudinally cut and transversely cut, a gel is obtained, in which hexagonal particles having a rectangular shape and a smooth surface are formed as main components. However, since cutting damage may occur, not only a hexagonal particle but also a mixture of polyhedron-shaped particles, the particles having a tetrahedron or more than a dodecahedron shape are 50% by mass with respect to the mass of the hydrogel polymer. In the above, the hydrous gel type polymer which becomes 100 mass% or less is obtained.

Polyhedral shapes of less than tetrahedron and / or polyhedrons of more than 12-sided polyhedrons are not preferable because of poor display performance when the absorbent resin obtained after drying them is swelled with an aqueous liquid.

The said cutting can be performed using various cutting means, such as a roller type cutter, a guillotine cutter, a slicer, a rolling cutter, a shredder, scissors, or a combination thereof, and is not specifically limited.

Next, an adhesion inhibitor will be described. The anti-adhesion agent includes at least one kind of a compound classified as a polyvalent metal salt, a polyhydric alcohol or a surfactant, and covers at least a part of the surface of the hydrous gel polymer to prevent adhesion of particles of the hydrogel polymer.

Although the usage-amount of an adhesion inhibitor is not specifically limited, 0.0015 mass% or more and 35 mass% or less with respect to solid content of a water absorbing resin, Preferably 0.002 mass% or more and 30 mass% or less, More preferably, 0.002 mass% or more and 25 mass% It is as follows. When the usage-amount is less than 0.0015 mass%, the releasability effect of the granular hydrogel obtained by cutting is small, and it becomes easy to reaggregate. On the other hand, when the amount of use is more than 35% by mass, not only an effect suitable for addition can be obtained, but also there is a concern that the physical properties of the water absorbent resin of the final product are lowered.

Examples of the polyvalent metal salts include aluminum chloride, polyaluminum chloride, aluminum sulfate, aluminum nitrate, potassium bisulfate, aluminum bisulfate, potassium alum, ammonium alum, sodium aluminate, calcium chloride, calcium nitrate, magnesium chloride, magnesium sulfate, Magnesium nitrate, zinc chloride, zinc nitrate, iron chloride (III), cerium chloride (III), ruthenium chloride (III), yttrium chloride (III), chromium (III) chloride, zirconium sulfate, zirconium hexafluoride, sodium zirconium hexafluoride , Ammonium zirconium carbonate, potassium zirconium carbonate, sodium zirconium carbonate, zirconium acetate, zirconium propionate and the like.

Especially, since the solubility with aqueous liquids, such as water, is favorable, it is preferable to use the salt which has these crystal waters. Particularly preferred are aluminum compounds, among which aluminum chloride, polyaluminum chloride, aluminum nitrate, potassium bisulfate, sodium bisulfate, potassium alum, ammonium alum, sodium alum, sodium aluminate are preferred, and aluminum sulfate is particularly preferred. desirable. As aluminum sulfate, the powder of hydrous crystals, such as aluminum sulfate 18 hydrochloride, aluminum sulfate 14-18 hydrochloride, etc. can be used most preferably. These may use only 1 type or may use 2 or more types together.

It is preferable to use a polyvalent metal salt as aqueous solution. Although it does not specifically limit as a density | concentration of aqueous solution of a polyvalent metal salt, Preferably it is 1 mass% or more and 50 mass% or less, More preferably, it is 3 mass% or more and 40 mass% or less, More preferably, it is 5 mass% or more and 30 mass% or less, Especially preferably, they are 10 mass% or more and 20 mass% or less.

When the concentration of the polyvalent metal salt aqueous solution is less than 1% by mass, a large amount of the polyvalent metal salt aqueous solution is required in order to impart releasability, and therefore, a large amount of energy is required in the subsequent drying step, which is not preferable. On the other hand, when the concentration of the polyvalent metal salt aqueous solution exceeds 50% by mass, the releasability is improved, but it is not preferable because the water solubility decreases and it is difficult to spray uniformly on the surface of the hydrogel polymer. In addition, the amount is too high, which is uneconomical.

Examples of the polyhydric alcohols include ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propanediol, dipropylene glycol, polypropylene glycol, 2,2,4-trimethyl-1, 3-pentanediol, glycerin, 2-butene-1,4-diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedi Methanol, 1,2-cyclohexanol, trimetholpropane, 2,3,4-trimethyl-1,3-pentanediol and the like can be used. Among them, propylene glycol is particularly preferred because of its high versatility. These polyhydric alcohols may use only 1 type, or may use 2 or more types together.

As said surfactant, anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant, etc. can be used, for example. Among the above surfactants, specific examples of the anionic surfactants include fatty acid salts such as mixed fatty acid sodium soap, semi-hardened fatty acid sodium soap, sodium stearate soap, potassium oleate soap and castor oil potassium soap; Alkyl sulfate ester salts, such as sodium lauryl sulfate, a higher alcohol sodium sulfate, and lauryl sulfate triethanolamine; Alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate; Alkyl naphthalene sulfonate, such as alkyl naphthalene sulfonate; Alkyl sulfo pumpkin salts, such as sodium dialkyl sulfo pumpkin; Alkyl diphenyl ether disulfonates such as sodium alkyl diphenyl ether disulfonate; Alkyl phosphates such as potassium alkyl phosphate; Polyoxyethylene alkyl (or alkyl allyl) sulfate ester salts such as sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether triethanolamine, and polyoxyethylene alkyl phenyl ether sodium sulfate; Specially reacted anionic surfactants; Special carboxylic acid type surfactants; naphthalene sulfonic acid formalin condensates such as sodium salt of β-naphthalene sulfonic acid formalin condensate and sodium salt of special aromatic sulfonic acid formalin condensate; Special polycarboxylic acid type surfactants; Polyoxyethylene alkyl phosphate ester etc. are mentioned.

Specific examples of nonionic surfactants include polyolefin oxides such as polyethylene glycol, polypropylene glycol, and polyethylene glycol-polypropylene glycol block copolymers; Polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, and polyoxyethylene nonylphenyl ether Oxyethylene alkylaryl ether; Polyoxyethylene derivatives; Sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate, sorbitan distearate Sorbitan fatty acid esters; Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan Polyoxyethylene sorbitan fatty acid esters such as trioleate; Polyoxyethylene sorbitol fatty acid esters such as tetraoleic acid polyoxyethylene sorbitol; Glycerin fatty acid esters such as glycerol monostearate, glycerol monooleate, and self-emulsifying glycerol monostearate; Polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate; Polyoxyethylene alkylamine; Polyoxyethylene hardened castor oil; Alkyl alkanolamide, etc. are mentioned.

Moreover, as cationic surfactant and amphoteric surfactant, Alkylamine salt, such as coconut amine acetate and stearyl amiacetate; Quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium chloride and alkylbenzyldimethylammonium chloride; Alkyl betaines such as lauryl betaine, stearyl betaine and lauryl carboxymethyl hydroxyethyl imidazolinium betaine; Amine oxides, such as lauryl dimethylamine oxide, etc. are mentioned. In addition to the above surfactants, it is also possible to use fluorine-based surfactants and siloxane-based surfactants.

Among these surfactants, particularly preferred are polypropylene glycol or polyethylene glycol-polypropylene glycol block copolymers. These surfactant may be in a small amount when added to the hydrous gel. In addition, these surfactants do not impair the physical properties of the hydrogel (for example, absorption magnification under pressure, etc.) even after the surface treatment is performed on the surface of the hydrogel after addition. In addition, these surfactants are preferred because of their high safety.

An anti-sticking agent should just contain at least 1 sort (s) of the compound classified into a polyvalent metal salt, polyhydric alcohol, or surfactant. Moreover, when using in combination of 2 or more types of anti-adhesive agents, you may use in the state which the compound classified into a polyvalent metal salt, polyhydric alcohol, or surfactant mixed, or may use separately. In the case of using a combination of a polyvalent metal salt, a polyhydric alcohol, and a surfactant, the amount of the polyvalent metal salt is not particularly limited. However, the polyvalent metal salt is a combination of a polyvalent metal salt and a polyhydric alcohol. It is preferable that it is 20 mass% or less with respect to total mass.

At least a part of the surface of the hydrous gel polymer should be coated with the anti-adhesive agent, but it is preferable that the entire surface is coated because the release effect of the anti-adhesive agent can be sufficiently obtained. In addition, although the said "coating" does not necessarily need to penetrate into the inside of a hydrous gel type polymer, an adhesive agent may penetrate to the inside, unless the function of a hydrous gel type polymer is impaired.

Although the water content of the said hydrous gel type polymer is not specifically limited, It is preferable that they are 40 mass% or more and 70 mass% or less, It is more preferable that they are 45 mass% or more and 65 mass% or less, It is especially preferable that they are 50 mass% or more and 60 mass% or less.

If the water content is less than 40% by mass, the exotherm during the polymerization reaction is high, and many foaming may occur in the water-containing gel polymer, which is not preferable. On the other hand, when the said moisture content exceeds 70 mass%, since a polymerization reaction may not be performed smoothly, it is not preferable. In addition, although the remaining monomers can be sufficiently reacted, it is not preferable because there is too much moisture left after drying, and a large amount of energy is required for drying and the work efficiency is lowered.

The mass average particle diameter of the hydrogel polymer is preferably 3 mm or more and 10 mm or less, more preferably 3 mm or more and 8 mm or less, and the particle size distribution of the hydrogel polymer is logarithmic standard deviation value of 0 or more and 0.25 or less. It is preferable.

In general, the larger the particle size of the hydrous gel, the more the residual monomers when dried under the same conditions tend to decrease. That is, when the hydrogel is dried, it proceeds inside as soon as drying (water evaporation due to temperature rise) starts from the surface layer. In the case of a small hydrogel having a small particle diameter, the water evaporates to the inside relatively quickly, so that the remaining monomer and The reaction of the polymerization initiator remaining in the hydrogel polymer becomes less likely to occur, and as a result, the remaining monomers are less likely to decrease. If the mass average particle diameter of the hydrous gel polymer is less than 3 mm, the particle size is small, which makes it difficult to reduce the residual monomer, which is not preferable.

On the other hand, in the case of a hydrous gel having a large particle diameter, the evaporation of water in the gel is slow despite the increase in the temperature inside the gel due to drying, so that the remaining monomer reacts with the polymerization initiator to easily reduce the remaining monomer. When the mass average particle diameter of the hydrogel polymer exceeds 10 mm, the remaining monomers tend to decrease for the same reason as described above. However, since drying time (energy) is required to dry the gel to the inside, it leads to a decrease in working efficiency. Not.

When the mass average particle diameter of the hydrogel polymer is 3 mm or more and 10 mm or less, and the particle size distribution of the hydrogel polymer is 0 to 0.25 in logarithmic standard deviation, the particle size of the hydrogel polymer is relatively large and the particle size distribution is Since it is uniform, a residual monomer can be made to be easy to react with the said polymerization initiator in a drying process.

Here, a "mass mean particle diameter" means the average particle diameter prescribed | regulated by the standard classified particle | grains. In addition, a logarithmic standard deviation value is a value which shows distribution of average particle diameter. In addition, the calculation method of an average particle diameter and a logarithmic standard deviation value is demonstrated in an Example.

Spraying and / or spraying of the anti-sticking agent may be carried out using conventionally known spraying means such as an atomizer, an air mixed spray device such as a 1 fluid nozzle, a 2 fluid nozzle, a liquid injection pump, a brush and a roller, and the like. It does not specifically limit. In addition, the number of spraying and / or spreading means is not particularly limited.

The method of spraying and / or spraying the anti-adhesive agent is not particularly limited as long as the anti-adhesion effect of the hydrous gel polymer by the anti-adhesive agent is obtained, but the adhesion to the longitudinal cutting, the transverse cutting blade, the fixed blade and / or the hydrous gel polymer It is preferred to include a step of spraying and / or spraying the inhibitor. In other words, as long as the anti-adhesion effect is obtained, the anti-adhesive agent may be directly sprayed and / or sprayed on the hydrous gel polymer, and sprayed and / or sprayed on the longitudinal cutting blade, the transverse cutting blade and / or the fixed blade, It may be attached to the hydrogel polymer through the longitudinal cutting blade, the horizontal cutting blade and / or the fixed blade.

In addition, as a coating | coating process, it is also possible to mix, spraying and / or spraying an adhesion inhibitor by introducing a mixing process other than a cutting process. The mixing device is not particularly limited as long as it is a mixing device usually used for mixing a liquid to a solid material, but a mixing device such as a radig mixer or a Nauta mixer is preferable.

The spraying amount and / or spraying amount of the anti-sticking agent to the longitudinal cutting blade, the horizontal cutting rotary blade, the fixed blade and / or the hydrous gel polymer is not particularly limited, but is 0.0015% by mass or more and 35% by mass or less with respect to the solid content of the absorbent resin. Spraying and / or spraying is preferred. More preferably, they are 0.0015 mass% or more and 25 mass% or less, Especially preferably, they are 0.0015 mass% or more and 20 mass% or less, Most preferably, they are 0.0015 mass% or more and 18 mass% or less.

If the spray amount and / or spray amount is less than 0.0015% by mass, the sufficient hydrogel effect cannot be coated, and thus sufficient adhesion preventing effect cannot be obtained. On the other hand, when the spray amount and / or spray amount exceeds 35% by mass, not only the energy required for drying increases but also the problem that the dust amount increases. In addition, in the case of using a polyvalent metal salt, the problem that the absorption ratio is lowered because the crosslinking reaction of the gel surface proceeds, and that the corrosion resistance to the cutter or the like is improved depending on the type of the polyvalent metal salt.

As a method of containing a chelating agent and / or a ultraviolet absorber, it is also possible to mix, spraying and / or spraying. The mixing device is not limited as long as it is a mixer normally used for mixing liquids, but a mixing device such as a radig mixer or a Nauta mixer is preferable.

In addition, in the said adhesion inhibitor, surfactant or polyhydric alcohol may be contained in the aqueous solution of ethylenically unsaturated monomer and / or hydrous gel type polymer in the said superposition | polymerization process. Although it does not specifically limit as a method to contain in the said water-containing gel type polymer, For example, surfactant and / or polyhydric acid are contained in the aqueous solution of the ethylenically unsaturated monomer which contains 30 mol% or more and 100 mol% or less of acrylic acid and / or an acrylate. The method of superposing | polymerizing after adding an alcohol and mixing uniformly is mentioned.

By containing at least 1 type of the compound classified into surfactant or polyhydric alcohol in the inside of a hydrous gel polymer, adhesion of the surface of a hydrous gel polymer and / or the cut surfaces at the time of cut | disconnection can be reduced.

The amount of the surfactant and / or polyalcohol contained in the hydrogel polymer is not particularly limited, but is 0.001% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 8% by mass or less, based on the solid content of the water absorbent resin. More preferably, they are 0.03 mass% or more and 5 mass% or less. When the amount of use is less than 0.001% by mass, the effect of reducing the adhesion between the cut surfaces of the hydrogel is small and easily reaggregated. On the other hand, when the amount of use is more than 10% by mass, the transparency of the water absorbent resin is impaired, for example, whitening occurs, which may reduce the display effect.

In addition, the surface including the inside and / or the cut surface of the hydrogel polymer may contain a chelating agent and / or an ultraviolet absorber. The method of containing the chelating agent and / or the ultraviolet absorber is not particularly limited. For example, as in the anti-adhesive agent, conventional methods such as an atomizer, a single fluid nozzle, an air-mixed spray device such as a two-fluid nozzle, and a liquid injection pump, etc. And a method of spraying and / or spraying the hydrous gel polymer using known means.

In addition, as with the anti-adhesive agent, the hydrogel polymer is sprayed and / or sprayed on the fixed blade and / or the rotary blade for longitudinal cutting or the transverse cutting to adhere to the hydrogel polymer through the fixed blade and / or the rotary blade. As a result, you may make it contain in the surface containing the inside or a cut surface of the said hydrogel polymer.

As the chelating agent, any compound having conventionally known metal ion blocking ability can be used without particular limitation. For example, (1) aminocarboxylic acids and salts thereof, (2) citric acid monoalkylamides and citric acid monoalkenylamides and salts thereof, (3) malonic acid monoalkylamides and malonic acid monoalkenylamides and salts thereof, (4) monoalkylphosphoric acid esters and monoalkenylphosphate esters and salts thereof, (5) N-acylated glutamic acid and N-acylated aspartic acid and their salts, (6) β-diketone derivatives, (7) tropolone derivatives Etc. can be mentioned. These chelating agents may be used alone or in combination of two or more thereof.

(1) As aminocarboxylic acid and its salt, aminocarboxylic acid which has three or more carboxyl groups, and its salt are preferable at the point of metal ion blocking ability. Specifically, nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, cyclohexane-1,2-diaminetetraacetic acid, N-hydroxyethylethylenediaminetriacetic acid, ethylene glycol di Ethyletherdiaminetetraacetic acid, ethylenediaminetetrapropionic acid, N-alkyl-N'-carboxymethylaspartic acid, N-alkenyl-N'-carboxymethylasparaginic acid, and these alkali metal salts, alkyl earth metal salts, ammonium salts or amine salts. have.

(2) Citric acid monoalkylamides and citric acid monoalkenylamides and their salts are obtained, for example, by dehydration of alcohols and citric acid.

(3) Malonic acid monoalkylamides and malonic acid monoalkenylamides and salts thereof are obtained by, for example, adding alpha -olefins to methyl malonic acid and then hydrolyzing them.

(4) Examples of the monoalkyl phosphate ester and the monoalkenyl phosphate ester and their salts include lauryl phosphate and stearyl phosphate.

(5) Examples of N-acylated glutamic acid and N-acylated aspartic acid and their salts include amine soft HS-11 and GS-11 sold by Ajinomoto, Kabushiki Kaisha.

(6) Examples of β-diketone derivatives include acetylacetone and benzoylacetone.

(7) As a tropolone derivative, a tropolone, (beta) -thujaplicins, (gamma) -tsuyaplicin, etc. are mentioned.

Among these chelating agents, Preferably they are aminocarboxylic acid which has 3 or more of carboxyl groups, and its salt, Especially diethylene triamine pentaacetic acid, triethylene tetraamine hexaacetic acid, cyclohexane-1,2- diamino tetraacetic acid, N -Hydroxyethylethylenediaminetriacetic acid and its salts are most preferred in terms of light resistance.

Moreover, there is no restriction | limiting in particular in the kind as said ultraviolet absorber, Usually, as long as it can absorb the light of 300 nm or more and 400 nm or less as a wavelength range efficiently, what kind of thing may be sufficient. Among these, as the benzophenone-based compound, (a) 2-hydroxybenzophenone-4-diglyceryl ether, (b) 2,2'-dihydroxybenzophenone-4-diglyceryl ether, (c) 2 -Hydroxybenzophenone-4,4'-diglyceryl ether, (d) 2,2'-dihydroxybenzophenone-4,4'-bisglyceryl ether, (e) 2-hydroxy-4- Methoxy-5-sulfobenzophenone sodium salt, (f) 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone sodium salt, (g) 2,2'-dihydroxy 4-methoxybenzophenone-5-sulfonic acid, (a) 2- (2'-hydroxy-4'-methoxy-5'-sulfophenyl) benzotriazole sodium salt, (child) 2- (2 ' -Hydroxy-4'-butoxy-5'- sulfophenyl) benzotriazole sodium salt, etc. are mentioned.

Among these, especially those which are benzophenone series and nonionic, that is, (a) to (d) are preferable.

The usage-amount of the said chelating agent and / or a ultraviolet absorber is 0.001 mass% or more and 10 mass% or less with respect to solid content of a water absorbing resin normally, Preferably they are 0.01 mass% or more and 5 mass% or less. When the amount of use exceeds 10% by mass, it is not economical to obtain an effect suitable for use, and the problem arises such that the amount of absorption decreases or the required amount of Group 8 transition metal ions becomes large. Moreover, when the said usage-amount is less than 0.001 mass%, the durability improvement effect of a water absorbing resin cannot be acquired.

Next, a drying process is demonstrated. The drying step is a step of drying the hydrous gel polymer. The drying method at this time is not particularly limited, and conventional drying methods such as using a ventilation band dryer, a rotary ventilation dryer, a stirring dryer, a fluidized bed dryer, a vibration flow dryer, and the like can be suitably used.

It is also preferable to perform high humidity drying using these dryers. High-humidity drying uses the said dryer, and is made to dry, contacting the object and the gas which contains a water vapor at least and has a dew point of 50-100 degreeC.

The temperature at the time of drying a hydrous gel type polymer can be applied as an ambient temperature or the temperature (material temperature) of a hydrous gel type polymer, and it is preferable to apply as a material temperature of a hydrous gel type polymer.

Here, an atmospheric temperature shows hot air temperature, and a material temperature shows the temperature measured by inserting the temperature sensor near the center in the thickness direction in the state which laminated | stacked 40 mm or more of hydrous gel type polymers, and dried.

It is preferable that they are 80 degreeC or more and 150 degrees C or less, and, as for the temperature at the time of drying the said hydrogel type | mold polymer, it is more preferable that they are 100 degreeC or more and 145 degrees C or less. It is especially preferable that they are 120 degreeC or more and 140 degrees C or less. If drying temperature is less than 80 degreeC, many hours are needed for reduction and drying of a residual monomer, and it is unpreferable. In addition, when the drying temperature exceeds 150 ° C., a dolby phenomenon in which water existing inside the hydrous gel polymer suddenly boils occurs, and the shape of the absorbent resin after drying becomes indeterminate, damaging the display effect. It is not preferable because there is possibility.

In addition, when drying the hydrogel polymer, the material temperature is raised rapidly, thereby drastically drying the cut gel surface layer portion of the anti-sticking agent, thereby drying the anti-sticking agent at the cut gel surface layer portion at once. Since components tend to be easily generated and dust may increase in the resulting water absorbent resin, a drying method is required to avoid a sudden increase in the material temperature. For example, a method of raising the temperature in multiple stages using a band dryer or the like or not There is a technique that uses a rotary ventilation dryer such as Roto Tsuru which is a product of Shikigaisha Okawara Seisakusho.

Thereby, the dust amount whose particle diameter with respect to the water absorbing resin obtained is 10 micrometers or less can be reduced. For example, the drying temperature of the first step may be 10 ° C or more and less than 120 ° C, preferably 30 ° C or more and less than 115 ° C, more preferably 50 ° C or more and less than 110 ° C. The drying time of the first step is preferably 10 minutes or more and 5 hours or less (preferably 10 minutes or more and 2 hours or less, more preferably 10 minutes or more and 1.5 hours or less).

The drying temperature of the second step may be 120 ° C or more and less than 180 ° C, preferably 130 ° C or more and less than 175 ° C, and more preferably 140 ° C or more and less than 175 ° C. The drying time of the second step is preferably 10 minutes or more and 5 hours or less, preferably 10 minutes or more and 2 hours or less.

By setting the drying temperature of the first step in this way, the hydrogel polymer is dried beforehand at a temperature of less than 120 ° C., and thus, when drying at the drying temperature of the second step, the water dolby phenomenon exists in the interior of the hydrogel polymer. Can be suppressed. In addition, when the temperature is raised to the drying temperature of the second step, the dolby can be suppressed as described above, so that drying can be performed at a high temperature of 120 ° C or more and less than 180 ° C without deforming the absorbent resin obtained. . Thereby, the shape of the water absorbing resin obtained is stable, and the water absorbing resin excellent in a display effect can be obtained.

Moreover, when the drying temperature of a 1st step is 120 degreeC or more, there exists a possibility that the dust amount of the obtained water absorbing resin may increase. In addition, when the drying temperature of the second stage is less than 120 ° C., it is necessary to spend a lot of time for drying, and when the drying temperature of the second stage is 180 ° C. or more, the dolby phenomenon of water existing inside the hydrogel polymer is It is unpreferable because there exists a possibility that the shape of the water absorbing resin obtained may become indefinite and the display effect may be impaired.

Rotary ventilation type dryer if used (e. G., Manufactured by whether or Okawa La yisaku Roto-through, etc. of the show), also different, the drum rotation speed is more than 5min ^-1, depending on the throughput of the function to the gel polymer dried 20min ^-1 or less It is preferable that it is preferable that the wind speed is 0.5 m / s or more and 20 m / s or less, and it is preferable that hot air temperature is 150 degreeC or more and 200 degrees C or less. By using the said roto trough, since drying which raises a material temperature continuously can be performed, it is possible to reduce the amount of dust after drying a hydrous gel type polymer.

By such a drying method, it becomes possible to effectively reduce the dust amount of the obtained water absorbing resin.

The water content of the water absorbent resin after drying is preferably 5% by mass or more and 30% by mass or less, more preferably 10% by mass or more and 25% by mass or less, particularly preferably 15% by mass or more and 25% by mass or less. In order to make water content less than 5 mass%, since a comparatively large drying time is required, it is not preferable. On the other hand, when the water content exceeds 30% by mass, the water absorbent resins tend to be reattached to each other when the water absorbent resin is stored for a long time, and the water content of the water absorbent resin itself increases, so that the amount of water that can be absorbed decreases. Not.

Content of the residual monomer of the said water absorbing resin is 0 mass ppm or more and 300 mass ppm or less, More preferably, they are 0 mass ppm or more and 200 mass ppm or less, Especially preferably, they are 0 mass ppm or more and 100 mass ppm or less. When the content is more than 300 ppm by mass, it is not preferable because there is a possibility of affecting the problems of hygiene and odor of the water absorbent resin. In addition, the measuring method of the said residual monomer is demonstrated in an Example.

 It is preferable that the mass mean particle diameters of the water absorbing resin which concerns on this invention are 2 mm or more and 10 mm or less, It is more preferable that they are 2.5 mm or more and 9.0 mm or less, It is further more preferable that they are 3.0 mm or more and 8.0 mm or less. A mass average particle diameter of less than 2 mm is undesirable because it may contain a large amount of the remaining monomers, and if it exceeds 10 mm, the moisture content becomes high, and it is easy to reattach when stored for a long period of time, and a relatively long drying time is required. It is not preferable because of the point.

The logarithmic standard deviation value of the particle size distribution of the water absorbent resin according to the present invention is preferably 0 to 0.25 or less, more preferably 0 to 0.23 or less, and even more preferably 0 to 0.20 or less. If the logarithmic standard deviation value is within this range, the particle size distribution of the particulate hydrogel becomes very sharp, indicating that a homogeneous particle as a whole is obtained.

In the present invention, the surface vicinity of the particulate water absorbing resin may be further crosslinked, whereby a water absorbent resin having a large absorption ratio under load can be obtained. In the surface crosslinking treatment, a crosslinking agent capable of reacting with a functional group of the water absorbent resin, for example, an acidic group, may be used, and a known crosslinking agent usually used for the application is exemplified.

As the surface crosslinking agent, for example, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3- Pentadiol, polypropylene glycol, glycerin, polyglycerine, 2-butene-1,4-diol, 1,4-butanediol, 1,5-pentadiol, 1,6-hexanediol, 1,2-cyclohexanedimethanol Polyhydric alcohol compounds such as 1,2-cyclohexanol, trimetholpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol and sorbitol; Polyhydric epoxy compounds such as ethylene glycol diglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether and glycidol; Polyvalent amine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine, and inorganic to organic salts thereof (for example, azitinium salts); Polyhydric isocyanate compounds such as 2,4-triylene diisocyanate and hexamethylene diisocyanate; Polyhydric oxazoline compounds such as 1,2-ethylenebisoxazoline; 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4- Dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1, 3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3 Alkylene carbonate compounds such as dioxan-2-one and 1,3-dioxopan-2-one; Haloepoxy compounds such as epichlorohydrin, epibromhydrin, and α-methyl epichlorohydrin, and polyhydric amine adducts thereof (for example, HAUMLES KAIMEN®); And polyvalent metal compounds such as hydroxides or chlorides such as zinc, calcium, magnesium, aluminum, iron, and zirconium.

Among these, polyhydric alcohol compounds, polyhydric epoxy compounds, polyamine compounds, salts thereof, and alkylene carbonate compounds are preferable. These surface crosslinking agents may be used independently or may be used together 2 or more types.

As quantity of a surface crosslinking agent, it is preferable to use 0.001 mass% or more and 10 mass% or less with respect to 100 mass% of water absorbing resin, and it is preferable to use 0.01 mass% or more and 5 mass% or less.

A normal dryer or a heating furnace can be used for heat processing. For example, a thin stirring dryer, a rotary dryer, a disk dryer, a fluidized bed dryer, an airflow dryer, an infrared ray dryer, a vibration flow dryer, etc. are mentioned. In that case, heat processing temperature becomes like this. Preferably it is 40 degreeC or more and 250 degrees C or less, More preferably, it is 90 degreeC or more and 230 degrees C or less, More preferably, it is 120 degreeC or more and 220 degrees C or less. As heat processing time, 1 minute or more and 120 minutes or less are preferable normally, 10 minutes or more and 60 minutes or less are more preferable.

Absorbent resin particles having a tetrahedral to tetrahedron shape having a mass average particle diameter of 2 mm to 10 mm or less, obtained by drying a particulate hydrogel polymer having a shape of tetrahedron to 12-hedron having a mass average particle diameter of 3 mm or more and 10 mm or less. It may be pulverized, classified, granulated, and used as an amorphous crushing absorbent resin.

The water absorbent resin obtained by the manufacturing method of this invention is inorganic fine particles, such as titanium oxide, a silicon oxide, and activated carbon; Organic fine particles such as polymethyl methacrylate; Hydrophilic fibers such as pulp; Synthetic fibers such as polyethylene fibers and polypropylene fibers; You may add surfactant, such as polyethyleneglycol and polyoxyethylene sorbitan monostearate, during the manufacturing process or after manufacture.

In addition, the novel absorbent polymer of the present invention is obtained by, for example, the above-mentioned manufacturing method, and the manufacturing method of the present invention can produce the present absorbent resin most efficiently. It may be.

(Manufacturing Method 2)

After cutting the hydrogel or its dried product, the mass average particle diameter of the hydrogel is 3 mm or more and 10 mm or less, or the mass average particle diameter of the dried product is 2 mm or more and 10 mm or less, The manufacturing method which selects only the absorptive resin of this application, when the ratio of particle | grains deviates from 50 mass% or more and 100 mass% or less.

As a manufacturing method which selects only the said water absorptive resin of this application, the method of selecting by using the sorting machine mentioned later, for example is mentioned. Moreover, it can also select using the rotary sorter mentioned later.

(Manufacturing method 3)

For the hydrogel polymer having a mass average particle diameter of 3 mm or more and 10 mm or less, and a tetrahedral or 12 tetrahedral shape obtained by polymerizing the monomer, the mass mean particle size is 3 mm or more and 10 mm or less from the polymerization vessel without undergoing a cutting step. A manufacturing method for taking out a hydrous gel polymer having a shape of tetrahedron or more and tetrahedron or less.

(2. cutter)

The cutter according to the present invention is a cutter for cutting a sheet-shaped hydrogel polymer (gel sheet), at least one longitudinal cutting blade for longitudinal cutting (width cutting) the hydrogel polymer, and the hydrogel polymer At least one transverse cutting blade and fixed blade for cutting (length cutting), and one or more sprays for spraying and / or spraying the anti-sticking agent onto the longitudinal cutting blade, trans cutting blade, fixed blade and / or hydrogel polymer And / or spreading means. Therefore, when the above cutting process is performed using this cutter, at least a part of the surface whose main component is hexagonal particles having a square shape and a smooth surface, is coated with an anti-sticking agent. A gel polymer can be obtained.

Hereinafter, the cutter will be described with reference to FIGS. 3 to 7. 3 is a longitudinal sectional view showing a configuration of a cutter according to the present embodiment. As shown in Figure 3, the cutter 100 is a longitudinal cutting blade (rolling cutter) (1, 2), scrapers (3, 4), horizontal cutting rotary blade (200), fixed blade (8), spraying and / Or a spreading device (spraying and / or spreading means) 9, 10, 11, 12, gel sheet inlet 13, and casing 14. If necessary, spraying and / or spreading devices 9 ', 10' may be provided. The horizontal cutting rotary blade 200 is composed of a rotating shaft 5 for horizontal cutting (length cutting), a blade 6, a horizontal cutting rotary body (7). In addition, the horizontal cutting rotary blade 200 and the fixed blade (8) constitutes a scissors cutting device.

Spraying and / or spreading devices (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10' are provided with an anti-stick agent for fixing blades 8, blades 6 and longitudinal cutting blades (rolling). Cutters (1, 2) and / or water-containing gel polymers (not shown). Since the cutter 100 is equipped with a spraying and / or spreading device (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10', the hydrogel polymer is effectively used as an anti-sticking agent. It can coat and can prevent the adhesion of the hydrous gel polymer after a cutting process effectively.

That is, the antifouling agent sprayed and / or sprayed from the spraying and / or spreading device (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10' includes a fixed blade 8, a blade. (6), fixed blades 8, blades 6, longitudinal cutting blades (rolling cutters) 1, 2 by being attached to longitudinal cutting blades (rolling cutters) 1 and 2 and / or hydrogel polymers; Since at least a part of the surface of the hydrogel polymer is coated, the adhesion of the hydrogel gel polymers after the cutting step can be effectively prevented.

The method of supplying the anti-sticking agent to the spraying and / or spreading device (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10' is not particularly limited, and conventionally known pumps and the like ( (As shown). Further, the number of spraying and / or spreading devices (spraying and / or spreading means) is shown in FIG. 3 by the spraying and / or spreading apparatus (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10. 6) are illustrated, but the present invention is not limited thereto and may be appropriately increased or decreased depending on the efficiency of spraying and / or spreading.

In addition, the position of the spraying and / or spreading device (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10' is not particularly limited, but the coating of the hydrous gel polymer with an anti-sticking agent is also possible. In order to improve the efficiency, it is preferable that the spraying and / or spraying to the hydrogel polymer, the blade 6, the fixed blade 8, the longitudinal cutting blade (rolling cutter) 1, 2 is possible.

In FIG. 3, the anti-sticking agent sprayed and / or sprayed from the spraying and / or spreading device (spraying and / or spreading means) 9, 10 is mainly attached to the longitudinal cutting blade (rolling cutter) 1, 2. The hydrogel polymer supplied from the gel sheet inlet 13 is cut before, simultaneously with, and / or after being cut through the longitudinal cutting blades (rolling cutters) 1 and 2, and then the longitudinal cutting blades ( From the rolling cutter) (1, 2) to the hydrogel polymer, the hydrogel gel polymer is coated.

In addition, the anti-sticking agent sprayed and / or sprayed from the spraying and / or spreading device (spraying and / or spreading means) 9 and 10 is mainly cut by the longitudinal cutting blades (rolling cutters) 1 and 2. It is attached directly to the hydrogel polymer and coats the hydrogel polymer.

In addition, the antifouling agent sprayed and / or sprayed from the spraying and / or spreading device (spraying and / or spreading means) 11, 12 is mainly a blade 6, a fixed blade 8, a transverse cutting body 7. ), The hydrogel polymer mainly from the blade 6, the fixed blade 8, before the hydrogel polymer is cut by the blade 6 and the fixed blade 8, simultaneously with, and / or after being cut. It transfers to a polymer and coats a hydrous gel type polymer.

It is also sprayed and / or sprayed from a spraying and / or spreading device (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10', and a longitudinal cutting blade (rolling cutter) 1, 2 ), The anti-adhesion agent attached to the members of the cutter 100, such as the blade 6, the horizontal cutting rotary body 7, and the like, prevents the hydrogel polymer from adhering to these members, and functions such as cutting force of these members. It also plays a role.

Further, as the spraying and / or spreading device (spraying and / or spreading means) 9, 10, 11, 12, 9 ', 10', an air-mixing spraying device such as an atomizer, a single fluid nozzle, or a two fluid nozzle And conventionally known spraying and / or spreading means such as a liquid injection pump, and the like, and are not particularly limited.

The rotating shaft 5 for horizontal cutting (length cutting) is for rotating the horizontal cutting rotary body (7). The power for rotating the rotating shaft 5 for horizontal cutting (length cutting) is not specifically limited, A well-known motor etc. may be used and you may rotate manually. In addition, although the rotation direction of the rotating shaft 5 for horizontal cutting (length cutting) in FIG. 3 is clockwise, it is not limited to this.

The horizontal cutting rotary body 7 includes a blade 6 at an outer circumference thereof, and operates according to the rotation of the rotary shaft 5 for horizontal cutting (length cutting). That is, in Fig. 3, the horizontal cutting rotary blade 200 composed of the rotary shaft 5 for horizontal cutting (length cutting), the blade 6, and the horizontal cutting rotary member 7, and the vertical cutting blade (rolling cutter) ( Two types of rotary blades of 1 and 2 are provided.

The ratio between the main speed of the longitudinal cutting blades (rolling cutters) 1 and 2 and the main speed of the horizontal cutting rotary blade 200 is determined by the length of the hydrogel-type polymer to be cut. The circumferential speed of 200) is determined by considering the effects of stiffness, temperature, and the like of the hydrogel polymer which has become a strand-shaped rectangle by longitudinal cutting. In general, when the main speed is too slow, it cannot be cut well, and the smoothness of the cutting surface tends to be lowered. When the main speed is too fast, the cut gel is less likely to have a constant dimension, and the size of the cut piece is not constant. There is a tendency.

The blade 6 is for transversely cutting (length cutting) the hydrogel polymer polymer cut by the longitudinal cutting blades (rolling cutters) 1 and 2 between the fixed blades 8. Although the arrangement | positioning and the number of the blades 6 are not specifically limited, Preferably it is about 1-10 pieces at an equal position, and the number is selected mainly considering a cutting speed and a cutting length. The number is even in many cases considering the balance, but may be an odd number.

The stationary blade 8 is for cutting the hydrogel-like polymer cut by the longitudinal cutting blades (rolling cutters) 1 and 2 between the blade 6 and transversely cutting it. Although the clearance of the fixed blade 8 and the blade 6 is not specifically limited, It is preferable that they are 0.005 mm or more and 0.05 mm or less, It is more preferable that they are 0.01 mm or more and 0.04 mm or less, It is 0.01 mm or more and 0.03 mm or less Particularly preferred.

If the clearance is less than 0.005 mm, since the clearance is too narrow, it is not preferable because the edges of the blades come into contact with each other under the influence of temperature change or the like and wear or damage occurs. If the clearance exceeds 0.05 mm, since the clearance is too wide, it is difficult to cut the hydrogel polymer, which is not preferable.

The longitudinal cutting blades (rolling cutters) 1 and 2 are for longitudinal cutting (width cutting) the hydrogel polymer supplied from the gel sheet inlet 13. Longitudinal cutting edges (rolling cutters) 1 and 2 tend to determine the diameter of the blade by the sheet width to be cut vertically, and as the sheet width increases, the cutting width is maintained to maintain the accuracy of the cutting width and to reduce the warpage of the blade. Will increase the diameter.

FIG. 5: is explanatory drawing which shows the structure which saw the longitudinal cutting blade (rolling cutter) 1 and 2 from the top. Fig. 6 is an explanatory view of the engaging portions of the longitudinal cutting blades (rolling cutters) 1 and 2, and Fig. 7 is an enlarged explanatory diagram of the engaging portions shown in Fig. 6. On the surfaces of the longitudinal cutting blades (rolling cutters) 1 and 2, as shown in Figs. 5 and in more detail, Figs. 6 and 7, respectively, the cutter blades are formed in the concave-convex shape so that the concavities and convexities are engaged with each other. The rotary shafts 15 and 16 are for transmitting the rotational force to the longitudinal cutting blades (rolling cutters) 1 and 2.

These interdigitated cutting edges (rolling cutters) 1 and 2 have the same dimensions, for example, and rotate in the direction of engaging with each other at the same rotational speed. The width, depth, and height of the irregularities of the blades formed to engage with each other may be determined according to the size required for the hydrogel polymer, for example, the width X1 in FIG. 7 is about 2 mm or more and about 10 mm or less, and the depth of the recess (X4). Is about 10 mm or more and about 15 mm or less, and the depth X5 of the convex part is about 10 mm or more and about 15 mm or less, and even when the concave part and the convex part are deeply engaged with each other, the gap required for the cut hydrogel polymer to pass through (in FIG. 7). (X3)) is generally formed such that it is about 10 mm or more and 25 mm or less.

In such a shape, the blades on the surface of the longitudinal cutting blades (rolling cutters) 1 and 2 are formed, and using the rotary shafts 15 and 16 of the longitudinal cutting blades (rolling cutters) 1 and 2 shown in FIG. By rotating two longitudinal cutting blades (rolling cutters) 1 and 2, by biting and cutting the hydrogel polymer supplied from the gel sheet inlet 13 and feeding it downward, the hydrogel polymer can be easily cut vertically. For example, it can be set as the rectangular shape of strand shape.

Further, in order to supply the hydrogel polymer to the longitudinal cutting blades (rolling cutters) 1 and 2, the hydrogel polymer is continuously taken out from the other end of the movable support, for example, the endless belt, and the longitudinal cutting blade (rolling cutter). When continuously performed using the method of digging into (1, 2), etc., the whole process can be continued and the production efficiency can be improved.

Next, a method of cutting the strand made into a rectangular shape horizontally will be described. The strands of the hydrous gel polymer cut into rectangular shapes, for example, by longitudinal cutting blades (rolling cutters) 1 and 2 rotating in mutually interlocking directions, are longitudinally cut at the upper edges of the scrapers 3 and 4. The fixed blade which peels from the outer peripheral part of the inner blade (A shown in FIG. 6) of the blade (rolling cutter) 1 and 2, descend | hangs between the scraper 3 and the scraper 4, and is provided in the lower end of the scraper 4 Reach to the position of (8). Usually, the strand of the hydrogel polymer is not attached to the outer edges (B shown in Fig. 6) of the longitudinal cutting blades (rolling cutters) 1 and 2.

In addition, it is preferable that the scrapers 3 and 4 are made of a material in which a strand of the hydrous gel polymer cut into a rectangular shape is attached, and thus clogging does not occur, or is coated. In particular, it is preferable to apply the coating in terms of cost. Specifically, in the longitudinal cutting blades (rolling cutters) 1 and 2, the horizontal cutting rotary blades 200, the casings 14, and the scrapers 3 and 4 shown in Fig. 4, the parts are in contact with the strands of the hydrogel polymer. It is preferable to coat the phosphorus scrapers 3 'and 4'.

Examples of the coating method include plating using a metal material, thermal spraying, vapor deposition, and the like, and a heat treatment method using a resin material is not particularly limited.

Examples of the coating material include non-tacky paints and lubricating paints, and specific examples of the resin material include PTFE (polytetrafluoroethylene) paints, FEP (tetrafluoroethylene / hexafluoropropylene copolymer) paints, and PFA. (Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) Fluorine-based paints such as paint system, bloso resin-modified paint system (original coating enamel), ETFE (ethylene / tetrafluoroethylene), silicone paint, polyvinyl chloride And paints based on polyamide.

As a fluororesin modified paint system (original coating enamel), the brand name 420-105 ONE COAT GRAY by Dupont Co., Ltd. can be used, for example. The components and content of this paint are 10-15 wt% of fluororesin, 10-15 wt% of organic binder resin, 15-25 wt% of methyl isobutyl ketone, 1-5 wt% of diacetone alcohol, 50-55 wt% of N-methylpyrrolidone, Titanium oxide 5-10 wt%.

The metal-based material is not limited as long as it does not adhere to the hydrogel polymer, but is, for example, a kani in which fine particles of fluorine-based resin are uniformly dispersed and vacanized in nickel and phosphorus electroless chemical treatments and carnizen plating films. Ceramic carnizen plating, titanium, etc. which made the microparticles | fine-particles, such as a metal oxide and carbide uniformly vacate, can be used in a plon plating and a carnizen plating film. Titanium can be coated with TiN, TiCN, TiAlN, CrN and the like by, for example, vacuum deposition, sputtering and ion plating.

It is preferable to use a durable titanium coating for the cutting edges (rolling cutters) 1, 2, blades 6 and fixed blades 8, which are wear-prone parts, and scrapers 3 It is preferable to use a fluorine-based paint for a part of, 4), or a part in which wear of the rotary blade holder, the casing, etc. is not a problem.

Reaching the position of the stationary blade 8, the strand having a rectangular shape downward from the position is cut by the cutting force acting between the blade 6 and the stationary blade 8, the shape is square and the surface is The main component is a hexahedron consisting of smooth surfaces, and preferably a small piece having a mass mean particle size of 3 mm or more and 10 mm or less and a logarithmic standard deviation value of the particle size distribution of 0.25 or less.

The cross-sectional shape in the transverse width direction of the one having a rectangular shape is the machine dimension after assembling the longitudinal cutting edges (rolling cutters) 1, that is, the uneven width X1 of the blade, the depth X4 of the recess, and the height of the convex portion ( X5), the depth of engagement X2, and the rotational speeds of the longitudinal cutting blades (rolling cutters) 1 and 2 are determined. Then, the blades provided on the rotational speed of the horizontal cutting rotary body 7 and the horizontal cutting rotary body 7 which rotate at the speed corresponding to the rotational speed of the longitudinal cutting blades (rolling cutters) 1 and 2 and the cutting length. By adjusting the number of (6), the mass average particle diameter of the hydrous gel polymer can be determined.

As described above, the scrapers 3 and 4 are for peeling the hydrogel polymer from the outer peripheral portion of the inner blades (A shown in FIG. 6) of the longitudinal cutting blades (rolling cutters) 1 and 2. The gel sheet inlet 13 is for supplying the hydrogel polymer polymerized in a sheet shape to the longitudinal cutting blades (rolling cutters) 1 and 2. The casing 14 is for preventing scattering of the cut hydrous gel polymer. The shape etc. are not specifically limited.

In addition, in the above description, the fixed blade (8) is provided at the lower end of the scraper (4), it was described as performing the horizontal cutting, the number, the installation position of the fixed blade (8) is not necessarily limited to this, in particular It is not limited. In addition, the fixed blade 8 may be used not only for horizontal cutting but also for vertical cutting.

In the cutter 100, it is preferable to lower the temperature of the hydrous gel-like polymer during cutting and / or to control the tension of the gel-like sheet in order to increase cutting efficiency and cut into a uniform shape. The preferable temperature of the hydrous gel polymer at the time of cleavage is 70 degrees C or less, More preferably, it is 60 degrees C or less, More preferably, it is 50 degrees C or less, More preferably, it is 40 degrees C or less, Especially preferably, it is 30 degrees C or less, Most preferably Is 20 degrees C or less.

Since the gel sheet is tensioned by the longitudinal cutting blades (rolling cutters) 1 and 2 when inserted into the cutter 100, the gel sheet is tensioned and usually its width is narrowed. Therefore, the tension of the gel sheet can be indirectly controlled by the width of the gel sheet. The width of the gel sheet is changed by the cutting speed or the conveying means until the cutting. The width of the gel sheet immediately before being inserted into the cutter is maintained at 90% or more of the width of the gel sheet without tension. It is good. In the state where tension is too long, large deformation occurs in the gel sheet before cutting, which is not preferable because a deviation or the like occurs in the width of the gel sheet after cutting.

As a method for lowering the temperature of the hydrogel polymer, a method of sufficiently performing cooling in the polymerization step, a method of forcibly cooling by cold air or the like before the cutting step, and / or a method of using a cooling belt may be mentioned. The cooling belt is, for example, a method in which cold water is brought into contact with the lower surface of the belt (inner side) while transferring the gel sheet to the upper endless belt made of SUS.

Further, when the cutting process is carried out through dried air or cold air, preferably dry air or cold air of 25 ° C. or lower, sticking of the hydrous gel polymer due to frictional heat during cutting, or adhesion of the cut hydrogel polymer Can be further reduced. Specific examples of the cutting machine include a square cutting pelletizer PM-300 manufactured by Tanaka Co., Ltd.

(3.Mixer)

In addition, the mixing apparatus of the hydrogel polymer after cutting is further mixed in order to uniformly coat the antifouling agent to the cleaved hydrous gel polymer and / or to add an antifouling agent to improve the antifouling property of the hydrogel polymer. It is preferable to mix by. It is also possible to utilize a mixing device for mixing chelating agents and / or ultraviolet absorbers.

The apparatus used in this case may be a conventional apparatus, for example, a radig mixer, a cylindrical mixer, a screw mixer, a screw extruder, a tubularizer, a Nauta mixer, a V mixer, a ribbon mixer, a twin kneader. , A fluid mixer, an airflow mixer, a rotary disk mixer, a roll mixer, an electric mixer, and the like, and any of continuous mixing and batch mixing may be used. In order to make the residence time in the apparatus and the spray amount of the antiadhesive agent constant in order to stabilize the antifouling property, a batch type is preferable, and as a device, the use of a radig mixer is preferable.

As a mixing method in the case of using a batch type reggae mixer, the following method is mentioned, for example. That is, the hydrogel polymer cut by the cutter 100 is introduced into the radiator mixer in a required amount, and then mixed while spraying an antifouling agent.

It is also possible to perform mixing for a predetermined time (preliminary mixing) before spraying the anti-sticking agent, and / or to continue mixing (post-processing) after the completion of spraying. Preliminary mixing disintegrates the hydrous gel, whereby the antifouling agent can be more uniformly coated on the hydrogel.

When mixed, the rotational speed of the blade is preferably 100min ^-1 or more 200min ^-1 or less, the number of revolutions of the side chopper is 1000min ^-1 at least 4000min ^-1 or less. Although the mixing time also varies depending on the capacity of the ready-mixed mixer and the filling rate of the material, it is preferable that the premixing is 0 seconds or more and less than 2 minutes, the main mixing is 10 seconds or more and less than 3 minutes, and the post mixing is preferably 0 seconds or more and less than 5 minutes.

It is also desirable to use or coat a material that prevents the adhesion of the hydrogel polymer into the interior of the device. It is particularly desirable to apply the coating in terms of cost.

Examples of the coating method include plating using a metal material, thermal spraying, vapor deposition, and the like, and a method of heat treatment using a resin material is not particularly limited.

Examples of the coating material include non-tacky paints and lubricity paints, specifically, PTFE (polytetrafluoroethylene) paints, FEP (tetrafluoroethylene / hexafluoropropylene copolymer) paints, and PFA. (Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) fluorine-based paints such as paints, fluororesin modified paints (original coating enamel), ETFE (ethylene / tetrafluoroethylene), silicone paints, polyvinyl chloride And paints based on polyamide.

As a fluororesin modified paint system (original coating enamel), the brand name 420-105 ONE COAT GRAY of DuPont Co., Ltd. can be used, for example. The components and content of this paint are 10-15 wt% of fluororesin, 10-15 wt% of organic binder resin, 15-25 wt% of methyl isobutyl ketone, 1-5 wt% of diacetone alcohol, 50-55 wt% of N-methylpyrrolidone, Titanium oxide is 5-10 wt%.

The metal-based material is not limited as long as it does not adhere to the hydrogel polymer. However, for example, fine particles of fluorine-based resin are uniformly dispersed and vaccinated in nickel and phosphorus electroless chemically treated Kanigen plating and Kanigen plating films. Ceramic carnizen plating, titanium, etc. which made the microparticles | fine-particles, such as a metal oxide and a carbide, vaccinate uniformly in a canoplon plating and a carnizen plating film, can be used. Titanium can be coated with TiN, TiCN, TiAlN, CrN and the like by, for example, vacuum deposition, sputtering and ion plating.

In addition, these mixers can also be used for mixing the surface crosslinking agent in the surface crosslinking of the water absorbent resin. In addition, anti-sticking agents are added by spraying and / or spraying, including conventionally known spraying such as atomizers, one-fluid nozzles, air-mixed spray devices such as two-fluid nozzles, liquid injection pumps, brushes, and rollers, and the like. And / or by means of spreading means, which is not particularly limited.

(4.absorbent resin)

 In one embodiment, the water absorbent resin according to the present invention polymerizes an ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less of acrylic acid and / or acrylate, and further has tetrahedral or more tetrahedral or less particles. A water-absorbent resin obtained by drying a hydrous gel polymer that is cut to 50 mass% or more with respect to the mass of the hydrous gel polymer, wherein the mass mean particle size is 2 mm or more and 10 mm or less, and the logarithm standard deviation value of the particle size distribution is 0 or more and 0.25 or more. It is as follows.

Moreover, it is preferable that content of the residual monomer of the said water absorbing resin is 0 mass ppm or more and 300 mass ppm or less.

In the acrylic acid and / or acrylate, the previously described acrylate monomer refers to acrylic acid and / or water soluble salts of acrylic acid. It is preferable to use the monomer which contains an acrylate monomer as a main component among ethylenic unsaturated monomers, since the water absorption performance and safety of the hydrous gel obtained are further improved.

The acrylates are alkali metal salts, alkaline earth metal salts, ammonium salts, hydroxyammonium salts and amine salts of acrylic acid having a neutralization rate in the range of 30 mol% or more and 100 mol% or less, preferably in the range of 50 mol% or more and 99 mol% or less. And alkylamine salts. Of the aqueous salts of the above examples, sodium salts and potassium salts are particularly preferred.

When the neutralization rate is 70 mol% or more and 100 mol% or less, the polymerization reaction proceeds particularly smoothly and is preferable because the yield of the water absorbent resin is increased. These acrylate monomers may be used independently and may use 2 or more types together.

As described above, when the hydrogel polymer formed into a sheet shape is longitudinally cut and transversely cut, particles having a tetrahedron shape or greater than a dodecahedron shape have 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer. A hydrous gel polymer is obtained. In the water absorbent resin obtained by drying this, the water absorbent resin having a mass mean particle size of 2 mm or more and 10 mm or less and a logarithmic standard deviation value of the particle size distribution is 0.25 or less is dried by a hydrogel polymer having a homogeneous particle size. It has a good dry state.

Moreover, when content of a residual monomer is 0 mass ppm or more and 300 mass ppm or less, the content of a residual monomer is very small and a high quality water absorbing resin with few odors and a sanitary problem can be obtained.

The water-absorbent resin having a water content of 5% by mass or more and 30% by mass or less with respect to the mass of the water absorbent resin is obtained by drying a hydrogel polymer having a water content desirable for the reaction between the remaining monomer and the polymerization initiator. The water absorbing resin which is 0 mass ppm or more and 300 mass ppm or less can be obtained.

In one embodiment, the water absorbent resin according to the present invention is an water absorbent resin obtained by drying a hydrous gel polymer having a polyhedral shape, and includes an anti-sticking agent comprising at least one kind of a compound classified into a polyvalent metal salt, a polyhydric alcohol, or a surfactant. At least a part of the surface of the furnace is coated with a water absorbent resin.

Such a water absorbent resin can be obtained by the method for producing a water absorbent resin according to the present invention. It is preferable that the spray amount and / or spray amount of the said adhesion inhibitor are 0.0015 mass% or more and 35 mass% or less with respect to solid content of a water absorbing resin.

If the said spray amount and / or spray amount is less than 0.0015 mass%, a water-containing gel polymer cannot fully be coat | covered, and water-containing gel polymers will become easy to adhere. Therefore, even when the hydrogel polymer is dried, it is not preferable because it tends to become agglomerates and does not dry smoothly. If the spraying amount exceeds 35% by mass, it is not preferable because it becomes difficult to handle due to stickiness and / or difficult to scatter during drying. In addition, it is not preferable because the amount of use is so large that it is uneconomical.

In one embodiment, in the water absorbing resin which concerns on this invention, 50 mass% or more of hexahedral-shaped particle | grains which consists of a surface whose shape is rectangular and the surface is smooth are contained with respect to solid content of the said water absorbing resin. The other particle is not particularly limited as long as it is a polygonal shape having a square shape and a flat surface, and is preferably a particle having a tetrahedron or more than a dodecahedron. Moreover, in the water absorbing resin which concerns on this invention, in order to improve durability, it is preferable to contain a chelating agent and / or an ultraviolet absorber.

(5. Separator)

The sorting machine which concerns on this embodiment sorts out the obtained water absorbing resin according to a desired mass average particle diameter after the said drying process. As an example, FIG. 8 shows the typical structure seen from the side of the sorter 300 which is a rotary sorter.

The sorting unit 300 includes an absorbent resin inlet 21 for injecting the absorbent resin, a first sorting unit 19 for removing the absorbent resin in the small release material, and a large release object. The 2nd sorting part 17 for removing a water absorbing resin is provided.

The water-absorbent resin of the small mold release product is an water-absorbent resin which is smaller than the mass particle size of the water absorbent resin after drying and which can pass through a mesh or a punching portion having a mesh size of 0.1 mm or more and 9 mm or less. It corresponds to the thing dried, cutting dregs, dust, etc. In addition, the said large release material is an absorbent resin which is larger than the mass mean particle diameter of the absorbent resin after drying, and cannot pass through the mesh or punching part of mesh size 2.0mm-10mm or less, For example, two or more absorbent resins are Aggregates, incomplete cuts, and the like are applicable.

By passing through the sorting process using the sorting machine 300, a mass mean particle diameter is 2 mm or more and 10 mm or less, and it becomes possible to make a logarithmic mean standard deviation into 0 or more and 0.25 or less.

In order to change the diameter of the water absorbent resin of the small mold release material to be removed and the water absorbent resin of the large mold release object, the diameter of the punching part 18 with which the 2nd sorting part 17 mentioned later is equipped, and the mesh of the mesh of the 1st sorting part 19 are mentioned. This can be done by changing the size.

The 1st sorting part 19 and the 2nd sorting part 17 are cylindrical, The weir 22 with smaller inner diameter than the 1st sorting part 19 and the 2nd sorting part 17 is provided between them. It is preferable that it is done. In addition, the second sorting section 17 is provided with a punching section 18 which is an opening, and the gas ejection nozzle 20 which is a gas ejection mechanism for injecting gas into the absorbent resin in the first sorting section 19 is 1. There are more than one place. Of course, what is necessary is just to set the installation position and number of gas injection nozzles 20 suitably, and are not specifically limited. For example, the small mold release can be further removed by blowing gas from at least one of the upper surface, the side surface, the lower surface, and the material inlet 21 of the first sorting unit 19 from the gas injection nozzle 20.

The material inlet 21 is an opening through which the absorbent resin is introduced. The material inlet 21 and the first sorting unit 19 are adjacent to each other, and the absorbent resin moves to the first sorting unit 19 as it is introduced. The 1st sorting part 19 is for removing the water absorbing resin which is a small particle | grain from the particle size distribution of the water absorbing resin, and is comprised from the cylindrical network.

The filling ratio of the material of the first sorting portion 19 is 5% by volume or more and 40% by volume or less, preferably 10% by volume or more and 30% by volume or less with respect to the volume of the first sorting portion 19. Is 10 volume% or more and 20 volume% or less. When the filling rate is less than 5% by volume, the residence time in the first sorting section 19 of the water absorbent resin is short, so that the effect of removing the small mold release product is insufficient. On the other hand, when the said filling rate exceeds 40 volume%, since the volume of the water absorbing resin in the 1st sorting part 19 is too big | large, the effect which removes a small mold release thing will reduce.

Although the diameter of the net | network of the 1st sorting part 19 is not specifically limited, When obtaining the die-shaped absorbent resin whose mass mean particle diameter is 4.0 mm, it is preferable to set it as 2.0 mm or more and 3.0 mm or less.

9 shows a cross-sectional view of the first sorting unit 19. As shown in FIG. 9, the 1st sorting part 19 is a structure which rotates in the direction of arrow D. FIG. Moreover, the gas injection nozzle 20 is provided in the circumference | surroundings of the 1st sorting part 19, and it is a structure which injects gas in the direction of arrow C. As shown in FIG. The gas to be injected is not particularly limited, but in terms of cost, it is preferable to use air. Preferably, dry air having a dew point of −10 ° C. or lower, particularly preferably dry air having a dew point of −20 ° C. or lower is preferred. Thus, by rotating the 1st sorting part 19, gas can be injected efficiently into the water absorbing resin 24 inside.

The rotation speed (retention time) of the first sorting unit 19 is 5 rpm or more and 50 rpm or less, preferably 10 rpm or more and 40 rpm or less, more preferably 10 rpm or more and 20 rpm or less, and less than 10 rpm, the material transfer speed is slow, and the first It is not preferable because the filling rate of the water absorbent resin in the sorting portion 19 is too high. On the contrary, if the material exceeds 30 rpm, the material transfer speed is high and the filling rate of the water absorbent resin in the first sorting unit 19 is too low.

Although it does not specifically limit as the gas injection nozzle 20, For example, well-known gas injection mechanisms, such as an atomizer, a single fluid nozzle, a wonder gun, can be used. In addition, the injection of gas may be performed continuously or discontinuously (intermittently).

Moreover, the hammers 23, 23a, 23b may be provided in the inside of the 1st sorting part 19 and / or the 2nd sorting part 17. As shown in FIG. When the first sorting portion 19 and / or the second sorting portion 17 rotate, the hammers 23, 23a, 23b vibrate in the direction of the arrow E, so the hammers 23, 23a, 23b vibrate. In addition, the first sorting unit 19 and / or the second sorting unit 17 vibrate. Due to this vibration, the deformed matter caught in the meshes of the first sorting section 19 and / or the second sorting section 17 is removed from the first sorting section 19 and / or the second sorting section 17, The blindness of the 1st sorting part 19 and / or the 2nd sorting part 17 can be prevented. In addition, it is preferable that at least one hammer 23, 23a, 23b is provided in the 1st sorting part 19 and / or the 2nd sorting device 17 each in order to prevent clogging of a blindfold.

The weir 22 is provided between the 1st sorting part 19 and the 2nd sorting part 17. As shown in FIG. Since the weir 22 has a smaller inner diameter than the first sorting section 19, when the water absorbing resin 24 in the first sorting section 19 is a small amount, the weir 22 is transferred to the second sorting section 17 by the weir 22. Movement is hindered. Therefore, the residence time in the 1st sorting part 19 of the water absorbing resin 24 increases, and a small mold release material can be cut. Thus, since a small mold release material becomes difficult to mix in the water absorbing resin obtained by cutting a small mold release material, the water absorbent resin excellent in a display effect can be obtained.

The second sorting section 17 has a plurality of punching sections 18. Since the diameter of the punching part 18 is larger than the desired mass average particle diameter of the water absorbing resin, and the absorbent resin of diameter larger than the diameter of the punching part 18 remains in the 2nd sorting part 17, a large release object can be removed. .

In addition, although the 2nd sorting part 17 may have the layered structure of a one-layer punching cylinder as shown in FIG. 10, as shown in FIG. 11, it may have the layered structure of several punching cylinders. In the sorter 300 shown in FIG. 8, which is an example of the sorter according to the present invention, the cylindrical second sorting unit 17 has a second sorting unit 17 therein and has a double structure. Moreover, the 2nd sorting part 17 is facing each other. On the other hand, the punching parts 18 provided in the 2nd sorting part 17 of 2 layers are formed so that they may not mutually face. When the punching portions 18 do not face each other, a portion of the punching portions 18 does not face each other.

12 is a schematic perspective view showing a structure in which the second sorting unit 17 has a two-layer structure. As shown in FIG. 12, the punching part 18 (marked with a solid line) with which the 2nd sorting part 17 was equipped is the punching part 18 provided with the other 2nd sorting part 17 (with a dashed line). Are not displayed facing each other. Moreover, it is preferable that the space | interval of the 2nd sorting part 17 of two layers is 1 times or more and 2 times or less of the mass mean particle diameter of a water absorbing resin, and it is more preferable that they are 1 times or more and 1.8 times or less. Since the space | interval of 2nd sorting part 17 comrades is set in this way, the water absorbent resin of a predetermined | prescribed mass mean particle diameter can pass through the punching part 18. As shown in FIG. On the other hand, since the long absorbent resin remains in the second sorting section 17, an absorbent resin having an even mass mean particle size can be obtained, and an absorbent resin having excellent display effect can be obtained.

Although the diameter of the punching part 18 is not specifically limited, When obtaining the die-shaped absorbent resin whose mass mean particle diameter is 4.0 mm, it is preferable to set it as 6.0 mm or more and 8.0 mm or less.

For example, in the sorter 300, the diameter of the net of the 1st sorting part 19 is set to 2.8 mm, and the 2nd layer 2nd sorting is specific, in order to obtain the die-shaped absorbent resin whose mass mean particle diameter is 4 mm. The diameter of each punching part 18 in the part 17 may set the diameter of inner punching to 7 mm, the diameter of outer punching to 9 mm, and the clearance of inner punching and outer punching to 7 mm.

As a specific example of a rotary sorting machine, the 2nd sorting part 17 of the Seiwatekojo Co., Ltd. product is SPSR-2000, SPSR-1500, SPSR-1000, SPSR-500, SPSR-250, and Seiwatet which are 1-layered structures. The second sorting unit 17 of Kojo products can be used a two-layer structure of SPSR-2000W, SPSR-1500W, SPSR-1000W, SPSR-500W, SPSR-250W and the like.

By using the sorting machine and sorting method described above, it is possible to effectively reduce dust having a particle size of 10 μm or less from the water absorbent resin obtained through the drying step. As the amount of dust is preferably 0mg / m ³ more than 500mg / m ³ or less, more preferably 0mg / m ³ more than 350mg / m ³ or less. When the amount of dust exceeds 500 mg / m ³ or more, dust is scattered when the absorbent resin is handled, and it is not preferable because the dust may be sucked.

The sorter 300 is a rotary sorter, but the sorter that can be used in the present embodiment is not limited thereto, and a vibration planar sorter may be used. 13 shows the structure of the vibration planar sorter 600. In the vibration planar sorter 600, the 1st sorting part 19 and the 2nd sorting part 17 'have a planar structure, and the 2nd sorting part 17' has a at least 2-layered structure. In addition, at least two layers of the second sorting portion 17 'are provided to face each other, and a first sorting portion 19 is provided below the plurality of second sorting portions 17'. The diameter of the net of the 1st sorting part 19 and the diameter of the punching part 18 'provided in the 2nd sorting part 17' are the same as that of the sorter 300. FIG. 14, the punching part 18 'shown by the solid line and the dotted line provided in the 2nd 2nd sorting part 17' does not mutually face each other, either.

The second sorting part 17 'of the vibration planar sorting part 600 is provided with a product inlet 37 for injecting the absorbent resin and a large release object ejection port 38 for ejecting the large release object. The inclination is formed so that the large release object ejection opening 38 side becomes lower from the inlet opening 37 to the large release object ejection opening 38. Although not shown in the vibration planar type separator 600, a vibration motor is provided, and as the vibration is applied, the absorbent resin introduced from the product inlet 37 moves to the second sorter 17 ', and the second sorting is performed. After passing through the punching part provided in the part 17 ', the small mold release material is removed from the first sorting unit 19 to be taken out from the small mold release outlet 39. Thereafter, the water absorbent resin selected on the first sorting unit 19 is obtained through the product outlet 40. The long release absorbent resin is discharged from the large mold release outlet 38 that does not pass through the punching portion.

As a specific example of a vibrating planar sorting machine, PS-280, PSL-300, PSL-400, PSLL-4000, etc. which are pellet sorting machines from Tanaka Co., Ltd. can be used.

When foreign matter (size and shape are the same as the water absorbent resin, but the metal flakes, dust, etc. which differ in color, and / or the water absorbent resin to which a small foreign material is attached, the colored absorbent resin, etc.) are mixed during manufacture of the water absorbent resin, In addition to impairing the display effect of the resin, when the foreign material is a metal, it is not preferable because it promotes inferiority of the absorbent resin or reduces the storage stability of the absorbent resin. Therefore, it is preferable to remove this water.

As a method of removing the foreign material, for example, there is a method of removing after being visually confirmed, a method of using a foreign material separator, a method of using an iron remover, and the like.

Electromagnets or permanent magnets may be used as the iron eliminator, preferably 2000 or more and 12000 or less Gaussian, more preferably 5000 or more and 12000 or less Gaussian, and particularly preferably 8000 or 12000 Gaussian.

(6. Maintenance agent for plant growth)

The maintenance agent for plant growth which concerns on this invention contains the water absorbing resin which concerns on this invention. That is, it includes the water absorbent resin produced by the method for producing the water absorbent resin according to the present invention. Since the water absorbent resin according to the present invention has few residual monomers that lower the physical properties of the water absorbent resin, it does not affect the problems of hygiene, bad smell and plant growth inhibition. The plant growth repair agent according to the present invention does not affect the problems of hygiene and odor. In addition, a sufficient amount of water can be introduced and, once absorbed, can save the long-term water supply of plants.

Hereinafter, the plant growth repair agent will be described. The water-retaining agent for plant growth should just contain the water absorbing resin which concerns on this invention, and it does not specifically limit about another component, For example, a polyvalent metal compound can be used preferably.

The polyvalent metal compound is a salt or hydroxide of a polyvalent metal, and is a divalent metal such as calcium, magnesium, barium or alkaline earth metal and a trivalent metal such as aluminum, or a transition metal such as zinc, iron, manganese, copper or molybdenum. And inorganic salts such as halides, nitrates, sulfates and carbonates, and double salts and organic salts such as lactic acid and fatty acids, and hydroxides and oxides.

Among them, calcium, aluminum, magnesium or zinc sulfates, carbonates, nitrates, chlorides, hydroxides, and oxides are preferable in order to provide a good environment for physiological action on plants such as gel stability after absorption and germination growth of plants. However, more preferably, they are divalent metal compounds, more preferably calcium compounds.

Examples of the calcium compound include calcium sulfate, calcium carbonate, calcium hydroxide, calcium oxide, calcium nitrate, calcium chloride, tricalcium phosphate, calcium borate, organic acid calcium such as calcium lactate, calcium citrate and calcium stearate, but are not particularly limited. Calcium sulfate, calcium carbonate, calcium hydroxide and calcium oxide are particularly preferred.

In addition, the polyvalent metal compound is water-soluble or cosmetic in water, solubility in 100 g of ion-exchanged water at 20 ℃ is 10.0g or less, preferably 1.0g or less, more preferably 0.5 It is g or less, Especially preferably, it is more than 0 and 0.3 g or less.

In the plant water-retaining material of this invention, when the solubility of a polyvalent metal salt is higher than the above, especially in the case of the water absorbent resin which has a carboxyl group, since the penetration of the polyvalent metal ion into the inside of water absorbent resin particle is quick, the monovalent pair in the inside of water absorbent resin The salt exchange with ions (such as sodium) causes internal metal crosslinking, which is not preferable because it greatly reduces the absorption characteristics as a water-retaining material such as absorption rate and absorption magnification. Moreover, in the polyhydric metal compound which is insoluble in water, it is not preferable because the polyvalent metal compound cannot adhere to or bind to the surface of the absorbent resin or penetrate into the vicinity of the surface.

The polyvalent metal compound is usually in the form of a powder containing crystallized water having a water content of 10% by mass or less, and its inner diameter is not particularly limited, but generally smaller than the mass average particle diameter of the water absorbent resin is used. In addition, the addition method and addition amount of the said polyvalent metal compound are mentioned later.

Although the method of manufacturing the plant repair material which concerns on this invention is not specifically limited, For example, the following method is mentioned.

(1) The manufacturing method which adds and mixes the polyvalent metal compound slurry of the density | concentration of 50 mass% or more in the state whose water content of a water absorbing resin is 50 mass% or less.

(2) The manufacturing method which adds and mixes aqueous solution or water vapor after addition-mixing the powder of a polyvalent metal compound in the powder state whose water content is 20 mass% or less, Preferably it is 10 mass% or less.

(3) The manufacturing method which mixes a polyvalent metal compound in powder in the state whose water content is 20 mass% or more and 50 mass% or less.

As a manufacturing method other than the method of said (1)-(3), the dry blending method etc. which add a polyvalent metal compound to water-absorbent resin (A) with a water content of 20 mass% or less, and mix powders together can be used, for example. Since it is preferable that the said polyvalent metal compound is supported, adhere | attached, or coat | covered on the surface of the said water absorbing resin (A), the manufacturing method of said (1)-(3) is preferable.

In addition, when the polyvalent metal compound is mixed in a solution or slurry state in a state where the water content of the water absorbent resin (A) exceeds 50% by mass, the polyvalent metal compound penetrates into the resin inside of the water absorbent resin, and the inside of the water absorbent resin It is not preferable because it is salt-crosslinked by a polyvalent metal compound, and the absorption property as a water-retaining material for plants is greatly reduced. In addition, even when a polyvalent metal compound is added to the monomer in the polymerization step, since the inside of the water absorbent resin is salt-crosslinked by the polyvalent metal compound, it is not preferable.

In the case of producing the plant water-retaining material according to the present invention by the method (1), the water content of the water absorbent resin is preferably low in order to prevent penetration of the polyvalent metal compound into the water absorbent material, and the preferred water content is 0. Mass% or more and 50 mass% or less, Next, 0 mass% or more and 40 mass% or less, More preferably, they are 0 mass% or more and 35 mass% or less, More preferably, they are 0 mass% or more and 30 mass% or less, Especially Preferably they are 0 mass% or more and 20 mass% or less, Most preferably, they are 0 mass% or more and 10 mass% or less.

In addition, the polyvalent metal compound is added as a solution or slurry. Many polyvalent metal compounds are mixed with a solvent such as an aqueous solution because of low solubility in water, and mixed with the absorbent resin in a slurry state.

The polyvalent metallized compound concentration in the slurry is preferably 50% by mass or more, more preferably 50% by mass or more and 90% by mass or less, particularly preferably 50% by mass or more and 80% by mass or less. When the said concentration is 90 mass% or more, since a slurry loses fluidity | liquidity and becomes a wet powder, ie, a wet state, it becomes difficult to add uniformly, and it is unpreferable.

The addition amount of the slurry is particularly limited by the kind of the polyvalent metal compound or the like. However, when the aqueous solution is used as a solvent for the slurry, the water content of the absorbent resin increases when the amount is large, so that the amount of the slurry is relative to the mass of the absorbent resin. The added amount of is preferably 0% by mass or more and 50% by mass or less, more preferably 0% by mass or more and 40% by mass or less, still more preferably 0% by mass or more and 30% by mass or less, particularly preferably 0% by mass or more and 20. Mass% or less, Most preferably, they are 0 mass% or more and 10 mass% or less, Most preferably, they are 0 mass% or more and 5 mass% or less.

The solvent used for the slurry containing the polyvalent metal compound is not particularly limited as long as it can uniformly disperse the polyvalent metal compound, but a polar solvent is preferable to carry or attach the polyvalent metal compound on the surface of the absorbent resin. In particular, water is preferable. Moreover, in order to adjust the fluidity | liquidity of the said slurry, you may add an organic or inorganic dispersing agent.

In the present invention, among various mixing methods, a method of spraying or dropwise mixing the slurry with the absorbent resin is preferable. In addition, depending on the type of the polyvalent metal compound, the slurry can be appropriately heated or cooled in consideration of temperature, solubility in water, slurry concentration with respect to temperature, and slurry fluidity. It is heating to boiling point over, but 20 degreeC or more and 80 degrees C or less are preferable.

In the case of producing the plant water-retaining material used in the present invention by the method (2), the water content of the water absorbent resin is 0% by mass or more and 20% by mass or less, preferably in a powder state of 0% by mass or more and 10% by mass or less, After addition-mixing the powder of a polyvalent metal compound, it is manufactured by adding and mixing aqueous solution or water vapor. When adding an aqueous liquid, the aqueous liquid added to the aqueous liquid as described in said (1) is used, As for the usage-amount, 0 mass% or more and 30 mass% or less are preferable, More preferably, 0 mass% or more and 20 mass% Hereinafter, More preferably, they are 0 mass% or more and 15 mass% or less, Especially preferably, they are 0 mass% or more and 10 mass% or less, Most preferably, they are 0 mass% or more and 5 mass% or less.

(7. Artificial ice for display)

The artificial ice for display according to the present invention includes the absorbent polymer according to the present invention. Although it does not specifically limit as components other than the said water absorbing resin, For example, you may contain the coloring agent etc .. The water absorbent resin according to the present invention has a polyhedron shape mainly composed of hexagonal particles, and the particle size thereof is larger than the particle size (mass average particle size of about 400 µm) of the usual absorbent resin. It may also include a sufficient amount of water. Therefore, it can maintain the external appearance similar to real ice, for example, can use it suitably for the sample of a product of a restaurant.

In addition, this invention is not limited to each structure demonstrated above, Various changes are possible within the range shown by a claim, and embodiment obtained by combining suitably the technical means disclosed in each embodiment also the technical scope of this invention. Included in

Example

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to this. Those skilled in the art can make various changes, modifications, and variations without departing from the scope of the present invention. In addition, the evaluation method is as follows.

(1) absorption magnification

Absorption magnification or absorption magnification after 48 hours under no pressure to 0.090% by mass saline solution, can be measured by the following method.

That is, after heat-sealing 0.200 g of absorbent resin uniformly in a bag (85 mm x 60 mm) of a nonwoven fabric (Nanco Co., Ltd. product, a brand name: Hitron paper, a model: GSP-22) product, heat-sealing Was immersed in a very excess (usually about 500 g) of 0.90% by mass aqueous sodium chloride solution (physiological saline).

After 48 hours, the bag was pulled up and dried for 3 minutes using a centrifugal separator (manufactured by Koksan Co., Ltd., Centrifuge: Model H-122) with a centrifugal force (250G) described in edana ABSORBENCY II 441, 1-99. After removal, the mass W 2 (g) of the bag was measured. In addition, the same operation was performed without using a water absorbent resin or a water absorbent resin composition, and the mass W1 (g) at that time was measured. And from these mass (W1, W2), the absorption magnification (g / g) was computed according to following formula (1).

Absorption magnification (g / g) = (mass W2 (g)-mass W1 (g)) / (mass of absorbent resin (g))-1

(2) remaining monomers

Content of the residual monomer in water absorbing resin can be measured by a conventionally well-known method. For example, after adding 1.0 g of water absorbent resin to 184.3 g of 0.90% by mass aqueous sodium chloride solution (physiological saline) and extracting under stirring for 2 hours, the water absorbent resin to be swollen is filtered using a filter paper, and the amount of monomer remaining in the solution The method of analyzing by liquid chromatography is mentioned. In this case, the calibration curve obtained by similarly analyzing the monomer standard solution of the existing concentration can be used as an external standard, and the residual monomer amount in the water absorbent resin can be obtained in consideration of the dilution ratio of the filtrate.

(3) Measurement of mass average particle diameter and logarithmic standard deviation value of hydrous gel polymer

30 g of the hydrogel polymer sample was administered to 1000 g of 20 mass% NaCl aqueous solution, and stirred for 120 minutes by rotating the stirrer chip at 300 rpm. 5 to 8 types of logarithmic standard deviations (R = 15.9%, 50.0%, and 84.9% in the following formula (2)) described below can be measured from the following sieve after the stirring is completed. THE IIDA TESTING SIEVE: Diameter 20cm, mesh size of sieve 16.0mm, 13.2mm, 11.2mm, 9.5mm, 8.0mm, 6.70mm, 5.6mm, 4.75mm, 4.0mm, 3.35mm, 2.8mm. 2.36 JIS standard sieve Z8801-1 (1998) of mm, 2.0 mm, and 1.0 mm) was selected, and 100 g of samples were added, and 6000 g of 20 mass% NaCl aqueous solution was added and classified. Samples on the classified sieves were thoroughly drained and weighed.

The particle size of the particulate hydrogel is set to w, the sieve mesh size is r, and the mass w0 = 30 g of the sample after the above classification and draining is performed, based on the following formula (2). Distributions were plotted on logarithmic probability plots. The particle size whose integrated sieve phase% R of the plot corresponded to 50 mass% was taken as the average particle diameter of a particulate hydrogel. In addition, Equation 2 is shown below.

R (α) = (w0 / w) ^1/3 × r

In the plot, the logarithmic standard deviation value (σζ) calculates the particle size (referred to as X1) of R = 84.1% and the particle size (referred to as X2) of R = 15.9% in the above-described integrated sieve phase, and these X1 and It calculated by the following formula (3) from X2.

σζ = (1/2) 1n (X2 / X1)

(4) Measurement of the mass average particle diameter of the water absorbent resin and the logarithmic standard deviation value

5 to 8 types of sieves (THE IIDA TESTING SIEVE) capable of measuring the logarithmic standard deviation (R = 15.9%, 50.0%, 84.9% in the formula (2)) described below from the sieves described later. : 20cm diameter, mesh size of sieve 16.0mm, 13.2mm, 11.2mm, 9.5mm, 8.0mm, 6.70mm, 5.6mm, 4.75mm, 4.0mm, 3.35mm, 2.8mm.2.36mm, 2.0mm, 1.0mm JIS standard sieve Z8801-1 (1998) was selected and 100 g of the sample was charged, and it classified for 5 minutes with the vibration classifier (IIDA SIEVE SHAKER, TYPE: ES-65 type, SER.No.0501). Samples on the classified sieves were weighed. The particle size distribution of the water absorbent resin is plotted on a logarithmic probability paper based on the above formula (2), with the mass of the water absorbent resin after the classification as w, the mesh size of the sieve as r, and the mass w0 = 30 g of the sample. It was. The particle size whose% R on the integrated sieve on the plot corresponds to 50 mass% was taken as the absorbent average particle diameter.

In the plot, the logarithmic standard deviation value (σζ) calculates a particle size of R = 84.1% (set to X1) and a particle size of R = 15.9% (set to X2) in the above-described sieve phase, and these X1 and It calculated from Formula (3) from X2.

(5) light resistance test

30 g of a gel in which 25 times of ion-exchanged water was completely absorbed with respect to the solid content of the water absorbent resin was placed in a 225 cc mayonnaise bottle, covered with a cover, and sealed, and then left for 1 week in the open air.

(6) Measurement of the shape (facet) of the hydrogel

By taking 30 g of the hydrogel polymer sample after the completion of cutting, and visually confirming one shape (facet), the mass percentage of the tetrahedron or more of the tetrahedron shape or the tetrahedral hydrogel polymer was calculated.

Concentration (mass%) of the hydrogel polymer having a tetrahedron shape or more than a dodecahedron shape or a hexagonal shape (mass%) = mass (g) / 30 (g of a tetrahedron shape or more than a dodecahedron shape or a hexagonal shape hydrogel polymer) ) × 100

(7) Water content measurement of solid gel polymer (solid content)

A small amount of the hydrogel polymer taken out from the polymerization reactor was cut into small portions and cooled quickly, and 4 g of the hydrogel gel polymer rapidly broken down by scissors was taken in a 50 mm inner chalet and dried in a 180 ° C stationary dryer for 16 hours.

Moisture content (mass%) of hydrous gel polymer = 100- (Muscle gel polymer mass (g) after drying / hydrogel polymer mass (g) x 100 before drying)

In addition, solid content can be inverted from a moisture content.

Solid content (mass%) = 100-water content (mass%)

(8) Water content measurement (solid content) of water absorbent resin

2 g of water-absorbent resins were taken in a chalet having an inner diameter of 50 mm, and dried in a 180 ° C. fixed dryer for 16 hours to calculate.

Water content (mass%) of water absorbent resin = 100- (water absorbent resin mass (g) after drying / water absorbent resin mass (g) * 100 before drying)

In addition, solid content can be inverted from a moisture content.

Solid content (mass%) = 100-water content (mass%)

(9) Measurement of dust amount

Vibration feeder 25 (Shinkodenki Chemical Co., Ltd. CF-2), digital dust meter 26 (Shibata Kagaku Chemical Co., Ltd. product P-5L), and support cup 27 are spaced as shown in FIG. Post it.

First, the absorbent resin 24 is placed on the vibrating feeder 25 by 1 kg, and the setting of the vibrating feeder 25 is adjusted to drop after about 1 minute after starting to drop from the vibrating feeder 25. Thereafter, 1 kg of the absorbent resin 24 is placed on the vibrating feeder 25, the absorbent resin 24 falls from the feeder, and the digital dust meter is operated for 1 minute. After 1 minute, the display of the digital dust meter is checked.

Example  One

37 mass% sodium acrylate aqueous solution 254.50 g, acrylic acid 29.50 g, 10 mass% polyethylene glycol diacrylate (n = 9) aqueous solution 0.747 g, ion-exchanged water 20.26 g, 10 mass% polyethylene glycol (brand name: polyethylene glycol 6,000, cantoka A monomer aqueous solution containing 6.25 g of an aqueous solution of Kaku Kabushiki Kaisha) was prepared. That is, an ethylenically unsaturated monomer containing 100 mol% of acrylic acid and sodium acrylate (excluding the crosslinking agent) was prepared. Nitrogen was blown into this monomer aqueous solution, and the dissolved oxygen concentration in aqueous solution was 0.1 ppm or less.

Subsequently, 1.41 g of 1.0 mass% acrylic acid solution and 1.41 g of 3.0 mass% sodium persulfate aqueous solution of hydroxycyclohexyl phenyl ketone (trade name Irgacure 184; manufactured by Chiba Specialty Chemical Co., Ltd.) were sequentially added, and then the monomer solution was 30 cm. The polymerization was carried out in a PFA batter of 30 cm with a irradiation distance of 450 W of high-pressure mercury lamp (trade name Toscure 401; manufactured by Harison Toshiba Lighting Co., Ltd.) at 60 cm.

The polymerization start temperature was 22 ° C. and reached 80 ° C. after 2 minutes and 30 seconds. After irradiating the high pressure mercury lamp for 5 minutes, the high pressure mercury lamp was turned off and the polymerization was terminated. The water content of the hydrogel at this time was 55% by mass.

The polymer sheet thickness was about 5 mm. The hydrous gel sheet after polymerization was cut into a square having a side of 5 mm by scissors cutting to prepare a hexagonal hydrous gel (1) having a square shape and a flat surface. That is, the hydrous gel of the hexagonal shape was 98.5 mass%. In addition, the mass average particle diameter of the hydrogel was 5.0 mm, and the logarithmic standard deviation value of the particle size distribution was 0.20. 300 g of this water-containing gel (1) was added to a 5 l-ready mixer (Matsubo Co., Ltd.), and 0.75 g (0.05 mass%) of 10 mass% ammonia sulfate solution in a syringe and 10 mass% Diethylene Triamine Pentaacetic Acid (trade name) 0.03 g (0.02 mass%) of aqueous solution of Keyrest PC 45 and Keyrest Co., Ltd. product was added dropwise, and mixed at a rotation speed of 200 min ⁻¹ for 1 minute. The hydrous gel after addition was non-aggregated.

This water-containing gel was spread on a wire mesh of 50 mesh (mesh size of 300 µm) and dried at 130 ° C. for 30 minutes to obtain a water-absorbent resin (1) having a water content of 20% by mass. The average particle diameter of the obtained water absorbing resin was 3.8 mm, and the logarithmic standard deviation value (σζ) was 0.19. In addition, the absorption magnification (hereinafter, referred to as 'CRC') was 41.0 g / g, and the residual monomer content was 100 ppm. In the light resistance test, no discoloration or deformation of the gel was observed.

In addition, the sieve of mesh size 8.0mm, 6.70mm, 5.6mm, 4.75mm, 4.0mm, 2.8mm, 2.0mm was used for the measurement of the average particle diameter of a water-containing gel type polymer and water absorbing resin, and a logarithmic standard deviation value.

Example  2

37 mass% sodium acrylate aqueous solution 407.2 g, acrylic acid 47.2 g, 10 mass% polyethylene glycol diacrylate (n = 9) aqueous solution 1.195 g, ion-exchanged water 40.35 g, 10 mass% polyethylene glycol (brand name: polyethylene glycol 6,000, cantoka A monomer aqueous solution containing 10.00 g of an aqueous solution manufactured by Gaku Kabushiki Kaisha) was prepared. That is, an ethylenically unsaturated monomer containing 100 mol% of acrylic acid and sodium acrylate (excluding the crosslinking agent) was prepared. Nitrogen was blown into this monomer aqueous solution, and the dissolved oxygen concentration in aqueous solution was made into 0.1 ppm or less.

Next, 2.256 g of 1.0 mass% acrylic acid solution and 2.256 g of 3.0 mass% sodium persulfate aqueous solution of hydroxycyclohexylphenyl ketone (trade name: Irgacure 184; manufactured by Chiba Specialty Chemical Co., Ltd.) were sequentially added, followed by monomer solution. The polymerization was carried out in a 30 cm × 30 cm PFA batter with a irradiation distance of 450 W of high-pressure mercury lamp (trade name Toscure 401; manufactured by Harison Toshiba Lighting Co., Ltd.). The polymerization start temperature was 22 ° C. and reached 88 ° C. after 4 minutes. The polymer sheet thickness was about 8 mm.

The hydrous gel sheet after polymerization was cut into 8 mm squares by scissors cutting, thereby preparing a hexagonal hydrous gel 2 having a square shape and a flat surface. In other words, the hexagonal hydrous gel was 97.0 mass%. In addition, the hexahedral hydrous gel content was 70 mass%. In addition, the mass average particle diameter of the hydrogel was 8.0 mm, and the logarithmic standard deviation value of the particle size distribution was 0.18. 300 g of this water-containing gel (2) was added to a 5 L-ready mixer (manufactured by Matsubo Corporation), and 0.75 g (0.05 mass%) of 10 mass% ammonia sulfate solution in a syringe and 2-hydroxybenzophenone-4- 0.105 g (0.05 mass%) of diglyceryl ethers were dripped, and it mixed for 1 minute at the rotation speed of 200min <^-1> . The hydrous gel after addition was non-aggregated.

This water-containing gel was spread over a wire mesh of 50 mesh (mesh size of 300 µm) and dried at 130 ° C. for 30 minutes to obtain a water-absorbent resin (2) having a water content of 19% by mass. The average particle diameter of the obtained water absorbing resin (2) was 6.8 mm, and the logarithmic standard deviation value (σζ) was 0.17. CRC was 41.0 g / g, and the residual monomer content was 80 ppm. In the light resistance test, no discoloration or deformation of the gel was observed.

In addition, the measurement of the average particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin includes sieves having a mesh size of 11.2 mm, 9.5 mm, 8.0 mm, 6.70 mm, 5.6 mm, 4.75 mm, 4.0 mm, and 2.8 mm. Used.

Example  3

43.7 kg of acrylic acid and 286 kg of 37 mass% sodium acrylate aqueous solution, 337 g of polyethylene glycol acrylate (n = 9), and 86.3 g of ion-exchanged water were sufficiently mixed to prepare an aqueous solution. That is, an ethylenically unsaturated monomer containing 100 mol% of acrylic acid and sodium acrylate (excluding the crosslinking agent) was prepared.

1.0 with a glass fiber-containing fluorine-based adhesive tape (trade name TGF Glass Cloth, manufactured by Yodogawa Hutech Co., Ltd.) on an endless steel belt, with a weir of 3.0 cm in height at intervals of 30 cm in width. The aqueous solution was fed at 1.2 kg / min to a belt polymerizer running at m / min. The aqueous solution was filled to a height of 5 mm. The aqueous solution was heated on a supply line through a feed port of a belt polymerizer such that the temperature of the aqueous solution was 22 ° C. In addition, nitrogen gas was continuously blown on the supply line, so that the dissolved oxygen was 0.5 ppm or less.

Into an aqueous solution with a dissolved oxygen level, these were added to 0.01 g / monomer moles of hydroxycyclohexylphenyl ketone (trade name Irgacure 184; manufactured by Chivas Specialty Chemicals Co., Ltd.), and 0.03 g / mole of sodium persulfate continuously on a supply line. The acrylic acid solution and the aqueous solution of the polymerization initiator were injected and mixed sufficiently (monomer concentration 40.0 mass%).

UV light was irradiated for 4 minutes with a high pressure mercury lamp (Toshiba MERCURYLUMP H400BL) placed at a height of 6 / 3m and 20cm from the aqueous liquid surface at equal intervals, and the aqueous liquid supplied to the belt polymerization machine was polymerized at 90 ° C after 3 minutes and 30 seconds. Peak temperature is shown. Nitrogen gas was supplied at 5 L / min and 5 L / min from the belt center part from the same position as the supply port of aqueous liquid.

The moisture content of the obtained hydrogel was 55.4 mass% and the thickness was 4 mm. The hydrogel from the polymerizer was fed to the cutter 100 shown in FIG. 3 at a rate of 1.0 m / min, and cut to have a cutting width of about 4 mm and a cutting length of about 4 mm. A hexahedral hydrous gel (3) having a rectangular shape and a flat surface was obtained. The water-containing gel content of the hexagonal shape was 85% by mass. In addition, the mass average particle diameter of the hydrogel was 4.0 mm, and the logarithmic standard deviation value of the particle size distribution was 0.20.

At that time, the sprayer 9, 10, 11 were blown out from the two-fluid nozzle (BIMV11002, manufactured by Ikeuchi Co., Ltd.) under conditions of propylene glycol 8 g / min and air pressure of 0.1 MPa, respectively. Using a pump, propylene glycol was sparged at a condition of 10 g / min. The propylene glycol used was 7.08 wt% based on the water absorbent resin solids.

The number of revolutions of 200min ^-1 was added to 5000g of hydrogels (3) in a 20-liter, ready-mixed mixer (Matsubo Co., Ltd., M20), and dropping 22.3g (0.10% by mass) of 10% by mass aqueous aluminum sulfate solution with a syringe. Mixed for 1 minute. At that time, the rotation speed of the side chopper of the reggae mixer was performed at 4000 rpm. The hydrogel was non-aggregated.

This water-containing gel was spread on a wire mesh of 50 mesh (mesh size of 300 µm) and dried at 130 ° C. for 30 minutes to obtain a water-absorbent resin (3) having a water content of 20% by mass. The average particle diameter of the obtained water absorbing resin (3) was 3.5 mm, and the logarithmic standard deviation value (αζ) was 0.18. CRC was 42.0 g / g, and the residual monomer content was 120 ppm.

In addition, sieves having a mesh size of 8.0 mm, 6.70 mm, 5.6 mm, 4.75 mm, 4.0 mm, 2.8 mm, and 2.0 mm were used for the measurement of the average particle diameter and the logarithmic standard deviation of the hydrogel polymer and the water absorbent resin.

Example  4

In Example 3, it carried out by the same method except having changed the adhesion inhibitor used by the cutter 100 into 50 mass% propylene glycol aqueous solution.

The hydrous gel after cleavage was in a non-aggregated state, and 80 mass% of the hexahedral hydrous gels. In addition, the mass average particle diameter of the hydrogel was 4.2 mm, and the logarithmic standard deviation value of the particle size distribution was 0.18.

This water-containing gel was spread over a wire mesh of 50 mesh (mesh size of 300 µm) and dried at 130 ° C. for 30 minutes to obtain a water-absorbent resin (4) having a water content of 19% by mass. The average particle diameter of the obtained water absorbing resin (4) was 3.7 mm, and the logarithmic standard deviation value was 0.17. CRC was 42.0 g / g, and the residual monomer content was 120 ppm.

Example  5

2 kg of sheet-like hydrogels obtained by the same polymerization method as in Example 3 were dried at 120 ° C. for 30 minutes in the form of a sheet. The moisture content of the sheet gel after drying was 39.3%.

The sheet gel after drying was cut in the same manner as in Example 3. The hydrous gel after cleavage was in a non-aggregated state, and 95 mass% of the hexahedral hydrogels. In addition, the mass average particle diameter of the hydrous gel was 5.0 mm, and the logarithmic standard deviation value of the particle size distribution was 0.18.

This water-containing gel was spread on a wire mesh of 50 mesh (mesh size 300 µm), and dried at 120 ° C. for 30 minutes to obtain a water-absorbent resin (5) having a water content of 20% by mass. The average particle diameter of the obtained water absorbing resin (5) was 4.5 mm, and the logarithmic standard deviation value was 0.18. CRC was 43.0 g / g and the residual monomer content was 115 ppm.

In addition, sieves having a mesh size of 8.0 mm, 6.70 mm, 5.6 mm, 4.75 mm, 4.0 mm, 2.8 mm, and 2.0 mm were used for the measurement of the average particle diameter and the logarithmic standard deviation of the hydrogel polymer and the water absorbent resin.

Example  6

300 g of the water absorbent resin (3) obtained in the same manner as in Example 3 was added to a 5 L redgauge mixer (Matsubo, Type; M5R), and stirred and mixed at 330 rpm for 15 seconds while adding 60 g of a 50 mass% concentration slurry of calcium sulfate. It was. After mixing, it was dried by hot air at 120 ° C. for 10 minutes to obtain a plant growth repair material (1).

150 ml of ion-exchanged water was added to a polypropylene container having an internal diameter of 80 mm and a height of 250 mm. Then, 1.5 g of the plant growth repair material (1) was weighed and placed in the container, and left for 1 hour to be used as a plant growth repair material. A gel medium (gel medium with 100 times absorption ratio) was prepared. Subsequently, about 30 grains of Kaiware radish were sown, a cover was made of a nonwoven fabric on the container, and cultured in a culture chamber (25 ° C., 500 Lux, 12 hours photoperiod) for 1 week to germinate.

After one week, the germinated kaiware radish was taken out, and the length of the branch leaf (ground length) from the base (branching point of root and branch) of the germinated solid to the tip of the leaf was 610 mm, and the length of the basement was germinated solid. The root length (basement length) from the base of the root to the tip of the main root was 560 mm. In addition, root hairs were identified.

Example  7

An artificial ice for display was produced by swelling the absorbent resin (3) obtained in the same manner as in Example 3 with ion-exchanged water 100 times.

Example  8

15.9 kg of acrylic acid and 173.4 kg of 37% by mass aqueous sodium acrylate solution, 104.6 g of polyethylene glycol diacrylate (n = 9), and 7.9 kg of ion-exchanged water, 15% by mass polyethylene glycol (trade name Polyethylene glycol 6000, Nippon Yushiki 2.7 kg of an aqueous solution from Kaisha) was sufficiently mixed to form a monomer aqueous solution. After adjusting this aqueous solution to 20 degreeC, nitrogen gas was inserted and dissolved oxygen was 1 ppm. After that, it was confirmed that air bubbles were missing by the naked eye.

Subsequently, hydroxycyclohexylphenyl ketone (trade name Irgacure 184: manufactured by Chivas Specialty Chemical Co., Ltd.) was dissolved in acrylic acid / water = 1/1 (mass ratio) to prepare a 3 mass% acrylic acid mixed solvent solution. Then, 3 mass% sodium persulfate aqueous solution was prepared.

A glass fiber-containing fluorine-based adhesive tape (trade name CHEMLAM6R, manufactured by Sangoban Co., Ltd.) was attached to the endless steel belt. A weir of 1.0 cm in height was installed thereon at intervals of 22 cm in width, and 1.4 kg / min of the aqueous monomer solution and 10 g of the mixed solution of acrylic acid water of the hydroxycyclohexylphenyl ketone were placed in a belt polymerizer moving at 1.0 m / min. / min, the aqueous sodium persulfate solution was supplied at 10 g / min.

Ultraviolet rays were irradiated for 4.3 minutes with a black light mercury lamp (Toshiba MERCURYLUMP H400BL-L), and the accumulated light amount at that time was 820 mJ / cm ² . The polymerization was carried out while supplying nitrogen gas at 50 L / min.

The moisture content of the obtained hydrous gel was 45.0 mass%, and thickness was 4.5 mm. The maximum reaching temperature at the time of polymerization was 90 degreeC. In the hydrous gel sheet, bubbles of 200 µm or more were not visually confirmed. The water-containing gel sheet from the belt polymerizer is transferred to the cutter 100 shown in FIG. 3 at a speed of 1.0 m / min via a horizontally installed roller conveyor, with a cutting width of about 4 mm and a cutting length of about 4 mm. It cut | disconnected so that it might be obtained, and the hexahedral hydrogel 4 which consists mainly of a square shape and the surface was smooth was obtained. As shown in Fig. 4, the scraper 3, 4 of the cutter 100 has a fluororesin enamel coating (surface) through which the hydrous gel sheet cut in the width direction by the slit rolls 1, 2, which are vertical cutting blades, passes. Since the coating was performed with 420-105 ONE COAT GRAY manufactured by DuPont Co., Ltd., clogging in the cutter 100 was not observed.

Moreover, by supplying 25 degreeC cold air to a hydrous gel sheet from the upper part of a roller conveyor, the surface temperature of the hydrous gel sheet immediately before entering into the cutter 100 was about 50 degreeC. Content of the tetrahedral hydrous gel was 99 mass%. In addition, the mass average particle diameter of the hydrogel was 4.4 mm, and the logarithmic standard deviation value of the particle size distribution was 0.19.

When cutting the hydrogel, the spraying nozzles 9, 10, 11 were used to spray 30 g / min of propylene glycol, respectively, using a spray nozzle, and the gear pump from the spraying device 12 was used to obtain 30 g / min of propylene glycol. It was introduced under conditions. The propylene glycol used was 19.05 mass% with respect to the water absorbent resin solid content.

40 kg of hydrogel (4) was put into a batch-type reggae mixer (manufactured by Matsubo, Ltd.) with a capacity of 130 L, and the blade rotation speed was 140 min ^-1 and the rotation speed of the sight chopper was 3000 min ^-1 and 10 mass%. 600 g of aluminum sulfate aqueous solution was mixed while spraying using a spray nozzle. The hydrogel was non-aggregated.

This hydrogel was poured on a wire mesh of 50 mesh (mesh size 300 μm) of a batch type hot air dryer, and hot air was shot for 30 minutes at a flow rate of 1 m / s at 105 ° C. The temperature of the hydrogel 4 was 30 minutes later. It became 105 degreeC, and after 50 minutes of hot air was blown at 150 degreeC and the air volume of 1 m / s, the hydrous gel (4) became 149 degreeC after 50 minutes, and the water absorbing resin (6) of 12 mass% of moisture content was obtained.

This water absorbent resin (6) was transferred to the sorting machine (300) at 1.5 kg / min, and the water absorbent resin (7) was obtained. In addition, a mesh having a mesh size of 2.8 mm was installed in the first sorting unit 19 of the sorting unit 300, and dry air was blown at 200 L / min from one place from the lower side of the first sorting unit 19. Moreover, the 2nd sorting part 17 has a double structure, The inner 2nd sorting part 17 is equipped with the punching part of diameter 7mm, The outer 2nd sorting part 17 is a 9mm diameter punching part. It was a structure provided. The clearance between the punching sections was 7 mm.

The mass average particle diameter of the obtained water absorbing resin (7) was 4.0 mm, and the logarithmic standard deviation value (σζ) was 0.18. CRC was 37.0 g / g, the residual monomer content was 280 ppm and the amount of dust was 220 mg / m ³ . In addition, in the water absorbing resin 7, the ratio of the hexagonal water absorbing resin was 99 mass%.

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  9

Drying was carried out in the same manner as in Example 8 except that the drying was performed with a band dryer. While passing through the hydrogel 4 at intervals of 120 minutes, the chambers divided into five at equal intervals were dried at 105 ° C for 1 to 3 chambers, 150 ° C for 4 to 5 chambers, and dried at 1.0 m / s for each chamber. (8) was obtained.

The temperature of the water-containing gel 4 was 105 ° C when the three chambers passed, and the temperature of the water-containing gel 4 was 148 ° C when the five chambers passed. In addition, the height of the hydrous gel 4 was made into 4 cm, and drying was performed.

The water absorption of the water absorbing resin 9 obtained after the treatment with the separator 300 was 13 mass%, the mass average particle diameter was 4.0 mm, and the logarithmic standard deviation value (σζ) was 0.19. CRC was 38.0 g / g, the residual monomer content was 290 ppm, the amount of dust was 250 mg / m ³ , and in the water absorbent resin 9, the proportion of the hexagonal water absorbent resin was 98% by mass. In addition, bubbles were not visually recognized inside the water absorbent resin 9.

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  10

Drying was carried out in the same manner as in Example 8 except that the drying was carried out using a rotary ventilation dryer (trade name Roto Tsuru SRTA-2, Okawara Seisakusho Co., Ltd.).

16 kg of hydrogels (4) were charged with SRTA-2, and dried at a hot air temperature of 190 ° C. and a wind speed of 1.0 m / s while rotating at 8 rpm. In addition, the punching part of the drum was 1.0 mm in diameter. The hydrogel 4 was brought into 110 ° C. after 40 minutes after being fed into the dryer, and further became 149 ° C. after 80 minutes. Drying was complete | finished after 80 minutes and the water absorbing resin (10) was obtained.

After the treatment with the separator 300, the water absorbing resin 11 obtained had a water content of 13.8 mass%, a mass average particle diameter of 3.9 mm, and a logarithmic standard deviation value σζ of 0.17. CRC was 42.1 g / g, the residual monomer content was 270 ppm and the amount of dust was 190 mg / m ³ . In addition, in the water absorbing resin 11, the ratio of the hexagonal water absorbing resin was 98 mass%.

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  11

Five metal pieces were added to the water absorbent resin 7 to prepare the water absorbent resin 12. After supplying the water-absorbent resin 12 to the iron eliminator at 1.5 kg / min, and again closely inspected with the naked eye, the metal pieces were completely removed.

In addition, the iron eliminator was passed through three stages in which three permanent magnets of 10 000 gauss of 10 cm in length were installed in parallel at 2 cm intervals.

Example  12

The first lamp of the black light mercury lamp (Toshiba MERCURYLUMP H400BL-L) of Example 8 was replaced with UV-152 / 1MNSC3-AA06, manufactured by Ushio Denki, in which a metal halide lamp (luminescence length 125 mm) was installed, The shutter was opened at 1.0 KW. The accumulated light amount at this time was 1300 mJ / cm ² . To the belt polymerizer moving at 1.5 m / min, 2.1 kg / min of the aqueous monomer solution prepared in Example 8 was supplied, 10 g / min of the hydroxycyclohexylphenyl ketone acrylic acid water mixed solvent solution, and 15 g / min of the aqueous sodium persulfate solution. .

The moisture content of the obtained hydrous gel was 45.1 mass%, and thickness was 4.5 mm. The maximum reaching temperature at the time of polymerization was 94 degreeC. Bubbles of 200 µm or more were not visually observed in the hydrous gel sheet. The water-containing gel sheet from the belt polymerizer was transferred to the cutter 100 shown in FIG. 3 at a speed of 1.5 m / min via a horizontally installed cooling belt. The cutter 100 was used to cut the cutting width so that the cutting width was about 4 mm and the cutting length was about 4 mm. Thus, a hexagonal hydrogel 7 having a hexagonal shape and a smooth surface was obtained. .

As shown in Fig. 4, the scraper 3, 4 of the cutter 100 has a fluororesin enamel paint (trade name 420-105) on the surface through which the hydrous gel sheet cut in the width direction by the longitudinal cutting edges 1, 2 passes. Since coating was performed with ONE COAT GRAY DuPont Co., Ltd., no blockage inside the cutter was observed.

In addition, since the cooling belt contacted the cold water of 13 ° C from the bottom, the surface temperature of the hydrous gel sheet immediately before entering the cutter 100 was about 40 ° C. In addition, the hexagonal hydrous gel content was 99 mass%, the mass average particle diameter of the hydrous gel sheet was 4.3 mm, and the logarithmic standard deviation value of the particle size distribution was 0.19.

When cutting the hydrogel, propylene glycol is blown onto the hydrogel under the conditions of 65 g / min of propylene glycol, respectively, from the spray nozzles of the spray apparatuses 9 ', 10', and 11, and further using a gear pump from the sprinkler 12 Propylene glycol was sparged at 65 g / min. Propylene glycol used was 27.45 mass% with respect to the water absorbent resin solid content.

60 kg of the hydrogel (7) was put into a 130 ^- liter batch ^-type radiator mixer (manufactured by Matsubo), and the blade rotation speed was 140 min ⁻¹ and the side chopper rotation speed was 3000 min ⁻¹ . Mixing was carried out while spraying 900 g of an aqueous 10 mass% aluminum sulfate solution. The hydrogel was non-aggregated.

1 to 3 chambers are 105 ° C, 4 to 5 chambers are 150 ° C, 1 to 3 chambers are up blown, and 2, 4, and 5 chambers are passed through the chamber in which the water-containing gel is divided into five at equal intervals at a height of 4 cm for 120 minutes. The chambers were dried at a blow down speed of 1.0 m / s in each chamber. The temperature of the hydrous gel 7 at the time of passing three chambers was 105 degreeC, and the temperature of the water absorbing resin at the time of five chambers was 148 degreeC. Then, the water absorbing resin (13) was obtained by the same sorting method as described in Example 8.

The water-absorbent resin 13 obtained had a water content of 12.5 mass%, a mass average particle diameter of 4.4 mm, a logarithmic standard deviation value of 0.19, a CRC of 51.0 g / g, a residual monomer content of 260 ppm, and a dust amount of 250 g / m ^3. It was. In addition, in the water absorbing resin 13, the ratio of the hexagonal water absorbing resin was 99 mass%.

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  13

The monomer aqueous solution which fully mixed the monomer of 15.9 kg of acrylic acid and 173.4 kg of 37 mass% sodium acrylate aqueous solution, 104.6 g of polyethyleneglycol diacrylate (n = 9), and 7.9 kg of ion-exchange water was created. After adjusting this aqueous liquid to 20 degreeC, when sending out a feed line at 1.75 kg / min, nitrogen gas was continuously blown out at 200 mL / min, and it has the same structure as the defoaming machine 400 shown in FIG. Degassing | defoaming was performed using the defoaming machine (brand name Quicktron 01 type Shin Nippon Sekiyu Co., Ltd. make). 1.4 kg / min of degassed monomer aqueous solution was discharged from the outlet hole of Quicktron, and 15 mass% of the aqueous solution of polyethyleneglycol (trade name: Polyethyleneglycol 6000 Nippon Yushi Co., Ltd.) 18.9 g / min, Example 8 The aqueous solution of hydroxycyclohexylphenyl ketone described was 10 g / min, and the aqueous solution of sodium persulfate described in Example 8 was supplied at 10 g / min.

The dissolved oxygen of the aqueous monomer solution was 5 ppm, and no bubbles were seen in the aqueous monomer solution. On the other hand, the aqueous monomer solution containing bubbles was discharged from the bubble discharge hole at 0.35 kg / min, which was fed back into the monomer preparation layer before degassing.

About this monomer aqueous solution, the process after superposition | polymerization was performed similarly to Example 8. Thus, the water content of the obtained hydrogel was 45.3 mass%, the thickness was 4.5 mm, and the logarithmic standard deviation value of the particle size distribution was 0.19.

In addition, the mass average particle diameter of the absorbent polymer 14 obtained after treating the hydrogel with the separator 300 was 4.0 mm, the logarithmic standard deviation value (σζ) was 0.19, and the CRC was 42.4 g / g. The content was 280 ppm and the amount of dust was 220 mg / m ³ .

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  14

As a method of removing the dissolved oxygen of the aqueous monomer solution adjusted to 20 ° C. prepared in Example 8, a degassing module having the same configuration as the degassing membrane module 500 shown in FIG. 2 (upper name MHF0504MBFT Mitsubishi Rayon Engineering Co., Ltd.) Product) was carried out in the same manner. Moreover, when deaeration was carried out at a vacuum degree of 7 kPa by a vacuum pump, the dissolved oxygen was 1 ppm and no bubbles were seen in the aqueous monomer aqueous solution. About this monomer aqueous solution, the process after superposition | polymerization was performed similarly to Example 8.

The water content of the obtained hydrous gel was 45.0 mass% and the thickness was 4.5 mm. In addition, the mass average particle diameter of the hydrous gel was 4.5 mm, and the logarithmic standard deviation value of the particle size distribution was 0.19.

After the treatment with the separator 300, the mass average particle diameter of the obtained absorbent polymer 15 was 3.9 mm, and the logarithmic standard deviation value (σζ) was 0.19. CRC was 42.0 g / g, the residual monomer content was 275 ppm and the amount of dust was 260 mg / m ³ .

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  15

In Example 8, drying was performed similarly except having performed hot air for 60 minutes by 150 degreeC and the air volume of 1 m / s, and performing it. 10 minutes after the start of drying, the temperature of the hydrous gel 4 was 120 ° C, and 20 minutes after the start of drying, 150 ° C.

In the water absorbent resin 16 obtained after the treatment with the separator 300, many bubbles such as a Dolby phenomenon occurred. The mass average particle diameter of the water absorbent resin 16 was 4.0 mm, the logarithmic standard deviation value (σζ) was 0.18, the residual monomer content was 280 ppm, and the amount of dust was 2520 mg / m ³ .

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  16

In Example 8, propylene glycol was prepared under the conditions of propylene glycol 60 g / min and air pressure 0.1 MPa from the two-fluid nozzles (BIMV11002, manufactured by Ikeuchi Co., Ltd.) of the spray apparatuses 9, 10, and 11, respectively. The same process was carried out except that the propylene glycol was introduced under a condition of 60 g / min using a gear pump from the sprinkling apparatus 12. In addition, the propylene glycol used was 38.10 wt% with respect to the water absorbent resin solid content.

The mass average particle diameter of the water absorbing resin 17 obtained after the treatment with the separator 300 was 4.1 mm, the residual monomer content was 225 ppm and the amount of dust was 3020 mg / m ³ .

In addition, the measurement of the mass mean particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin showed that the mesh size was 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, 2.0 mm. Was used.

Example  17

In Example 13, the monomer aqueous solution adjusted to 20 DEG C was supplied at 1.4 kg / min through the liquid inlet of the two-fluid nozzle, nitrogen gas was injected at 200 mL / min from the gas inlet side, and a deaerator (brand name Quick Tron) 01 type, Shin-Nippon Seki Yukagaku Co., Ltd.) was not used. About this monomer aqueous solution, the process after the polymerization process was performed similarly to Example 13.

The moisture content of the obtained hydrogel was 45.3 mass%, and thickness was 4.5 mm. It was confirmed that many bubbles were mixed in this hydrous gel. In addition, the hexagonal hydrogel content after cutting was 90 mass%, the mass average particle diameter of the hydrogel was 4.6 mm, and the logarithmic standard deviation value of the particle size distribution was 0.24.

The mass mean particle diameter of the absorbent polymer 18 obtained after the treatment with the separator 300 was 4.2 mm, the logarithmic standard deviation value (σζ) was 0.23, the CRC was 42.4 g / g, the residual monomer content was 230 ppm, and the dust The amount was 200 mg / m ³ . In addition, many bubbles were visually confirmed inside the water absorbent resin 18.

In addition, the measurement of the mass average particle diameter and the logarithmic standard deviation value of the water-containing gel polymer and the water absorbent resin was performed with a sieve having a mesh size of 8.0 mm, 6.70 mm, 5.60 mm, 4.75 mm, 4.0 mm, 3.35 mm, 2.8 mm, and 2.0 mm. Was used.

Comparative example  One

A hydrogel sheet was prepared in the same manner as in Example 1, and the hydrogel gel sheet was cut into a square having a side of 1 mm by scissors cutting to prepare a hexagonal hydrogel 5. The hydrous gel 5 caused reaggregation. The water-containing gel content of the hexagonal shape was 100% by mass. In addition, the mass average particle diameter of the hydrogel was 1.0 mm, and the logarithmic standard deviation value of the particle size distribution was 0.20.

This hydrous gel was spread on a wire mesh of 50 mesh (mesh size 300 µm) and dried at 130 ° C. for 30 minutes, whereby fusion of the gel occurred to form a lump. The moisture content of the obtained water absorbing resin was 16.5 mass%, and CRC was 41.0 g / g. In addition, the residual monomer content was 450 ppm. The yellowing of the gel appeared in the light resistance test.

Comparative example  2

The hydrous gel sheet was produced by the composition which removed the polyethyleneglycol from the composition of Example 1, the hydrous gel sheet was cut | disconnected to the square whose side was 4 mm by scissors cut, and the hexagonal hydrogel 6 was prepared. The water-containing gel content of the hexagonal shape was 100% by mass. In addition, the mass average particle diameter of the hydrogel was 4.0 mm, and the logarithmic standard deviation value of the particle size distribution was 0.20. The hydrous gel 6 caused reagglomeration.

The hydrogel was spread on a wire mesh of 50 mesh (mesh size 300 µm) and dried at 130 ° C. for 30 minutes, whereby fusion of the gel occurred to form a lump. The moisture content of the obtained water absorbing resin was 24.0 mass%, and CRC was 41.0 g / g. In addition, the residual monomer content was 550 ppm.

In the manufacturing method of the water absorbing resin which concerns on this invention, a sorting process is a process of removing a small mold release product and a large release material, It is preferable that it is a manufacturing method of obtaining the water absorbing resin whose mass mean particle diameter is 2 mm or more and 10 mm or less.

The mass average particle diameter of the said water absorbing resin is the said range, and the display effect of a water absorbing resin can be improved further by removing a small mold release material and a large mold release material by the said sorting process.

The manufacturing method of the water absorbing resin which concerns on this invention is a manufacturing method of the water absorbing resin which uses the said cutter, The at least 1 place of a longitudinal cutting blade, a scraper, a horizontal cutting rotary blade, and a casing with which the said cutter was equipped, It is preferable that it is covered by at least 1 sort (s) of non-tacky paint, lubricity paint, and a metallic material.

Thereby, in the cutting process, it can suppress that the problem by clogging of a hydrous gel type polymer arises.

In the method for producing an absorbent polymer according to the present invention, the cutting step is characterized in that the water-containing gel polymer has hexagonal shape particles whose surface is square and the surface is smooth, and the mass of the water-containing gel polymer is 50 mass%. It is preferable to cut | disconnect so that it may become more than 100 mass%. Hexahedral particles can be easily produced by longitudinal and transverse cutting of the hydrogel polymer. Therefore, the cutting process can be made efficient, and the size of the hydrogel polymer can be easily adjusted.

Method for producing a water-absorbent resin according to the present invention is that the coating process comprises a step of spraying and / or spraying the anti-sticking agent to the longitudinal cutting blade, horizontal cutting rotary blade, fixed blade and / or hydrous gel type polymer. desirable.

According to the above constitution, at least the anti-sticking agent may be directly attached to the hydrogel polymer, or indirectly attached from the longitudinal cutting blade and / or the transverse cutting blade, the fixed blade to cover the hydrogel polymer. Therefore, adhesion of water-containing gel polymers can be effectively prevented, and reattachment of water-containing gel after cutting can be prevented. Further, in order to promote release of the longitudinal cutting blade, the fixed blade, the rotary blade, and the hydrous gel polymer, the cutting force of the longitudinal cutting blade, the fixed blade, and the rotary blade can be maintained.

The method for producing the water absorbent resin according to the present invention includes 0.0015% by mass or more and 35% by mass or less of the anti-adhesive agent, based on the solid content of the water absorbent resin, in the longitudinal cutting blade, the horizontal cutting rotary blade, the fixed blade, and / or the hydrogel polymer. Spraying and / or spraying is preferred.

According to the above structure, at least a part of the surface of the hydrogel polymer can be coated. Therefore, adhesion of water-containing gel polymers can be effectively prevented, the drying can be performed smoothly, and the content of the remaining monomers of the water absorbent resin can be reduced.

The method for producing a water absorbent resin according to the present invention also includes, in the polymerization step, an aqueous solution and / or hydrous of an ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less (excluding the crosslinking agent) of acrylic acid and / or acrylate. It is preferable to include the process which contains surfactant and / or polyhydric alcohol in a gel polymer.

According to the above constitution, since the surfactant or the polyhydric alcohol has the effect of preventing the adhesion of the hydrogel polymers, the adhesion of the hydrogel polymers by the surface coating can be further enhanced, and the content of the remaining monomers in the water absorbent resin is further increased. You can do less.

In addition, as a coating | coating process, it is also possible to mix, mixing and spraying an adhesion inhibitor by introducing a mixing process other than a cutting process.

It is preferable that the manufacturing method of the water absorbing resin which concerns on this invention also includes the process of including a chelating agent and / or an ultraviolet absorber on the surface containing the inside and / or a cut surface of the said hydrous gel type polymer.

According to the above constitution, since ultraviolet rays, which trap one of the metal ions which are one of the causes of inferiority of the absorbent resin with the chelating agent, and / or which are one of the causes of the inferiority of the absorbent resin, are absorbed by the ultraviolet absorber, A water absorbent resin having high durability against and the like can be produced.

The manufacturing method of the water absorbing resin which concerns on this invention makes water content of the said water absorbing resin into 5 mass% or more and 30 mass% or less by drying the water-containing gel type polymer after the said coating process at 80 degreeC or more and 150 degrees C or less, and remain | survives of the said water absorbing resin It is preferable to make content of a monomer into 0 mass ppm or more and 300 mass ppm or less. According to the said structure, it can dry favorably, without foaming a hydrous gel type polymer, and can reduce content of a residual monomer. Therefore, a water absorbent resin which does not affect hygiene and odor problems can be obtained, and a water absorbent resin which is non-aggregated and excellent in display effect can be obtained.

In the manufacturing method of the water absorbing resin which concerns on this invention, it is preferable to go through the process of drying the water-containing gel type polymer after the said coating process at 10 to 120 degreeC.

Thereby, since the process of drying an absorbent resin at the temperature of 10 degreeC or more and less than 120 degreeC goes through, the amount of dust produced can be reduced suitably.

In the method for preparing the absorbent polymer according to the present invention, the stationary polymerization is made of a sheet thickness of 3 mm or more and 10 mm or less, and the mass average particle diameter of the absorbent resin that has been cut, coated, and dried is 2 mm or more and 10 mm or less. It is preferable to make the logarithmic standard deviation value of particle size distribution into 0 or more and 0.25 or less.

The water absorbent resin whose mass mean particle size and logarithmic standard deviation of the particle size distribution are in the above range is obtained by drying a hydrogel polymer having a uniform particle size. That is, it is obtained by drying the hydrous gel polymer in a state where a reaction between the remaining monomer and the polymerization initiator remaining in the hydrogel polymer is likely to occur. Therefore, the water absorbent resin with few content of a residual monomer can be obtained.

The cutter according to the present invention is preferably at least one of a longitudinal cutting blade, a scraper, a horizontal cutting rotary blade, and a casing, which is provided in the cutter, and is covered by at least one kind of a non-tacky paint, a lubricity paint, and a metallic material. .

Thereby, in the inside of a cutter, it can suppress that the problem by clogging of a hydrous gel type polymer arises.

The water absorbent resin according to the present invention preferably has a mass average particle size of 2 mm or more and 10 mm or less after the screening step, and a logarithmic standard deviation value of the particle size distribution is 0 or more and 0.25 or less.

When the said water absorbent resin goes through a sorting process, the water absorbent resin excellent in a display effect can be obtained.

As for the water absorbing resin which concerns on this invention, it is preferable that content of a residual monomer is 0 mass ppm or more and 300 mass ppm or less.

The said water absorbing resin is obtained by drying the water-containing gel polymer in a state in which a reaction between the remaining monomer in the water-containing gel polymer and a polymerization initiator is likely to occur. Therefore, the water absorbent resin with little content of the residual monomer of the said range can be obtained.

It is preferable that the water content of the water absorbing resin which concerns on this invention is 5 mass% or more and 30 mass% or less. The said water absorbent resin is obtained by drying the hydrous gel type polymer which has a water content preferable for reaction of a residual monomer and the said polymerization initiator, As a result, a water content becomes 5 mass% or more and 30 mass% or less with respect to the mass of a water absorbing resin. Therefore, it becomes water-absorbent resin with few content of a residual monomer.

In addition, the absorbent polymer according to the present invention is an absorbent resin obtained by drying a hydrogel polymer having a polyhedral shape, and at least one kind of a compound in which at least a part of the surface of the absorbent resin is classified as a polyvalent metal salt, a polyhydric alcohol or a surfactant. It is coat | covered with the adhesion inhibitor to contain.

According to the above constitution, the anti-sticking agent acts as a release agent on at least a part of the surface of the water absorbent resin having a polyhedral shape. Therefore, it becomes difficult to aggregate the hydrogel polymers, so that the adhesion of the hydrogel polymers can be significantly reduced. In addition, even if an aggregate is formed, for example, it can be easily dissociated into primary particles simply by applying a weak external force to the aggregate. Therefore, drying can be performed smoothly and content of the residual monomer of a water absorbing resin can be reduced.

As for the water absorbing resin which concerns on this invention, it is preferable that content of the said adhesion inhibitor is 0.0015 mass% or more and 35 mass% or less with respect to solid content of a water absorbing resin. According to the said structure, content of the said anti-sticking agent becomes a preferable range in order to prevent aggregation of hydrous gel type polymers. Accordingly, the water-absorbent resin having a uniform particle shape can be obtained, the drying can be smoothed, and the content of the remaining monomers of the water-absorbent resin can be reduced.

It is preferable that the absorptive resin which concerns on this invention contains 50-100 mass% of hexahedral-shaped particle | grains which consist of a surface with a square shape and the surface is smooth, with respect to the mass of the said hydrous gel type polymer. Hexahedral particles can be easily produced by longitudinal and transverse cutting of the hydrogel polymer. Therefore, as long as a hexagonal particle | grain is a main component, the water absorbing resin with few content of a residual monomer can be obtained cheaply and easily.

The water absorbent resin according to the present invention preferably also contains a chelating agent and / or an ultraviolet absorbent. According to the above structure, ultraviolet rays which are one of the causes of trapping the metal ions which are one of the causes of inferiority of the absorbent resin with the chelating agent and / or of the inferiority of the absorbent resin are absorbed by the ultraviolet absorber, for example, in the outdoors, etc. The durability of the water absorbing resin to be used can be improved.

As mentioned above, since the manufacturing method of the water absorbing resin which concerns on this invention coat | covers at least one part of the surface of the hydrous gel type polymer which has a polyhedron shape with an anti-adhesive agent, and it dries, it dried smoothly, Preferably it remains The water absorbent resin which reduced content of a monomer can be obtained.

Therefore, this invention can be used suitably as a manufacturing method of the water absorbing resin with little physical property fall, and the said water absorbing resin can be used for uses, such as a plant growth repair agent and a display artificial ice.

Specific embodiments and examples made in the detailed description of the present invention are for the purpose of clarifying the technical contents of the present invention, and should not be construed in a narrow sense only to such specific embodiments. It can be carried out by changing variously within the scope of the claims.

Claims (27)

(1) An ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less (excluding the crosslinking agent) of acrylic acid or acrylate is subjected to stationary polymerization in sheet form to obtain a hydrogel polymer having a water content of 40 mass% or more and 70 mass% or less. Polymerization process, (2) A cutting step of cutting the hydrous gel polymer so that particles having a tetrahedral to 12-hedron shape having a mass average particle diameter of 3 mm or more and 10 mm or less are 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer. After drying the water-containing gel polymer to have a water content of 5% by mass or more and 60% by mass or less, particles having a tetrahedron or more tetrahedron having a mass average particle diameter of 2 mm or more and 10 mm or less are added to the mass of the water-containing gel polymer. Cutting step of cutting so as to be 50% by mass or more and 100% by mass or less; (3) at least on the surface of the hydrous gel polymer with an anti-adhesion agent comprising at least one of a compound classified as a polyvalent metal salt, a polyalcohol or a surfactant before, simultaneously with or after cutting the hydrogel polymer; A coating process of covering a part, (4) A method for producing an absorbent polymer, characterized by comprising a drying step of drying the coated hydrogel polymer. The method for producing a water absorbent resin according to claim 1, further comprising a sorting step of sorting the obtained water absorbent resin after the drying step. The method for producing an absorbent resin as set forth in claim 2, wherein said sorting step is a step of removing a small mold release product and a large mold release product, and a water absorbent resin having a mass average particle diameter of 2 mm or more and 10 mm or less is obtained. The method of claim 1, wherein the cutting step is a manufacturing method of the absorbent resin using a cutter. At least one of the longitudinal cutting blade, the scraper, the horizontal cutting rotary blade, the casing provided in the cutter is covered with at least one of a non-tacky paint, a lubricity paint, and a metal-based material. 2. The cutting step according to claim 1, wherein the cutting step comprises a hydrogel polymer having a tetrahedral particle composed of a plane having a square shape and a surface having a smooth surface, wherein the hydrogel polymer is 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer. Method for producing a water-absorbent resin, characterized in that for cutting to be. The method of claim 5, wherein the coating step comprises spraying or spraying the anti-adhesive agent on the longitudinal cutting blade, the horizontal cutting rotary blade, the fixed blade, or the hydrogel polymer. The said anti-sticking agent is sprayed or sprayed on the said longitudinal cutting blade, the horizontal cutting rotary blade, the fixed blade, or a hydrous gel type polymer so that it may be 0.0015 mass% or more and 35 mass% or less with respect to solid content of an absorbent polymer. Method for producing a water absorbent resin, characterized in that. The surfactant or the aqueous solution of the ethylenically unsaturated monomer or water-containing gel polymer according to claim 1, further comprising at least 30 mol% to 100 mol% (excluding crosslinking agent) of acrylic acid or acrylate in the polymerization step. A process for producing a water absorbent resin, comprising the step of containing a polyhydric alcohol. The method for producing an absorbent resin according to claim 1, further comprising a step of including a chelating agent or an ultraviolet absorber on a surface of the hydrogel polymer having an interior or a cut surface. The moisture content of the said water absorbing resin is made into 5 mass% or more and 30 mass% or less by drying the hydrogel polymer after the said coating process at 80 degreeC or more and 150 degrees C or less, and content of the residual monomer of the said water absorbing resin is made into 0 mass ppm or more and 300 mass ppm or less, The manufacturing method of the water absorbing resin characterized by the above-mentioned. The method for producing an absorbent polymer according to claim 2, wherein the water-containing gel polymer after the coating step is dried at 10 ° C or more and less than 120 ° C. The method of claim 1, wherein the stationary polymerization is made of a sheet thickness of 3mm or more and 10mm or less, the mass mean particle size of the water absorbent resin after the cutting, coating and drying process is 2mm or more and 10mm or less, and the logarithmic standard deviation of the particle size distribution The value is 0 or more and 0.25 or less, The manufacturing method of the water absorbing resin characterized by the above-mentioned. A cutter for cutting sheet-shaped hydrogel polymer, At least one longitudinal cutting blade for longitudinally cutting the hydrogel polymer, At least one transverse cutting blade and a fixed blade for cutting the hydrogel polymer crosswise; And at least one spraying or spraying means for spraying or spraying the anti-sticking agent onto the longitudinal cutting blade, the horizontal cutting blade, the fixed blade, or the hydrogel polymer. 14. The cutting machine according to claim 13, wherein at least one of the longitudinal cutting blade, the scraper, the horizontal cutting rotary blade, and the casing of the cutter is covered with at least one of a non-adhesive paint, a lubricity paint, and a metallic material. cutter. The ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less of acrylic acid or an acrylate is superposed | polymerized, and the particle | grains of tetrahedron to 12-hedron shape are 50 mass% or more and 100 mass% with respect to the mass of a hydrous gel type polymer. An absorptive resin obtained by drying the hydrogel polymer cut into less than or equal to, wherein the absorbent resin has a mass mean particle size of 2 mm or more and 10 mm or less, and a logarithmic standard deviation value of the particle size distribution is 0 or more and 0.25 or less. The water-absorbent resin according to claim 15, wherein the mass mean particle size after the screening step is 2 mm or more and 10 mm or less, and the logarithmic standard deviation value of the particle size distribution is 0 or more and 0.25 or less. The water-absorbent resin according to claim 15, wherein the content of the remaining monomers is 0 mass ppm or more and 300 ppm or less. 16. The water absorbent resin according to claim 15, wherein a water content of the obtained water absorbent resin is 5% by mass or more and 30% by mass or less. A water absorbent resin obtained by drying a hydrous gel polymer having a polyhedral shape, wherein at least a part of the surface of the water absorbent resin is coated with an anti-sticking agent containing at least one kind of a compound classified as a polyvalent metal salt, a polyhydric alcohol, or a surfactant. Absorbent resin characterized by the above-mentioned. The water absorbent resin according to claim 19, wherein the content of the anti-sticking agent is 0.0015% by mass or more and 35% by mass or less with respect to the solid content of the water absorbent resin. The water-absorbent resin according to claim 15, wherein the hexagonal particles each having a shape having a rectangular shape and having a smooth surface are contained in an amount of 50% by mass or more and 100% by mass or less with respect to the mass of the hydrogel polymer. . 20. The water absorbent resin according to claim 19, wherein the hexagonal particles having a rectangular shape and having a smooth surface are contained in an amount of 50 mass% or more and 100 mass% or less with respect to the mass of the hydrogel polymer. The absorbent resin according to claim 15, further comprising a chelating agent or an ultraviolet absorber. 20. The absorbent polymer according to claim 19, further comprising a chelating agent or an ultraviolet absorber. A sorter for sorting a water absorbent resin after drying, comprising a gas ejection mechanism. (1) An ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less (excluding the crosslinking agent) of acrylic acid or acrylate is subjected to stationary polymerization in sheet form to obtain a hydrogel polymer having a water content of 40 mass% or more and 70 mass% or less. Polymerization process, (2) A cutting step of cutting the hydrous gel polymer so that particles having a tetrahedral to 12-hedron shape having a mass average particle diameter of 3 mm or more and 10 mm or less are 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer. After drying the water-containing gel polymer to have a water content of 5% by mass or more and 60% by mass or less, particles having a tetrahedron or more tetrahedron having a mass average particle diameter of 2 mm or more and 10 mm or less are added to the mass of the water-containing gel polymer. Cutting step of cutting so as to be 50% by mass or more and 100% by mass or less; (3) at least on the surface of the hydrous gel polymer with an anti-adhesive agent comprising at least one kind of a compound classified into a polyvalent metal salt, a polyalcohol or a surfactant before, simultaneously with or after cutting the hydrogel polymer; A coating process of covering a part, (4) ethylenic containing 30 mol% or more and 100 mol% or less of the water absorbent resin manufactured by the manufacturing method of the water absorbent resin characterized by including the drying process which dries the coated hydrogel type polymer. As a water absorbent resin obtained by superposing | polymerizing an unsaturated monomer and drying the hydrogel type | mold which cut | disconnected so that the particle | grains of tetrahedron to 12-hedron shape may be 50 mass% or more and 100 mass% or less with respect to the mass of a hydrous gel type polymer, A plant growth repair agent comprising an absorbent resin having an average particle diameter of 2 mm or more and 10 mm or less and a logarithmic standard deviation value of the particle size distribution being 0 or more and 0.25 or less. (1) An ethylenically unsaturated monomer containing 30 mol% or more and 100 mol% or less (excluding the crosslinking agent) of acrylic acid or acrylate is subjected to stationary polymerization in sheet form to obtain a hydrogel polymer having a water content of 40 mass% or more and 70 mass% or less. Polymerization process, (2) A cutting step of cutting the hydrous gel polymer so that particles having a tetrahedral to 12-hedron shape having a mass average particle diameter of 3 mm or more and 10 mm or less are 50% by mass or more and 100% by mass or less with respect to the mass of the water-containing gel polymer. After drying the water-containing gel polymer to have a water content of 5% by mass or more and 60% by mass or less, particles having a tetrahedron or more tetrahedron having a mass average particle diameter of 2 mm or more and 10 mm or less are added to the mass of the water-containing gel polymer. Cutting step of cutting so as to be 50% by mass or more and 100% by mass or less; (3) at least on the surface of the hydrous gel polymer with an anti-adhesive agent comprising at least one kind of a compound classified into a polyvalent metal salt, a polyalcohol or a surfactant before, simultaneously with or after cutting the hydrogel polymer; A coating process of covering a part, (4) ethylenic containing 30 mol% or more and 100 mol% or less of the water absorbent resin manufactured by the manufacturing method of the water absorbent resin characterized by including the drying process which dries the coated hydrogel type polymer. As a water absorbent resin obtained by superposing | polymerizing an unsaturated monomer and drying the hydrogel type | mold which cut | disconnected so that the particle | grains of tetrahedron to 12-hedron shape may be 50 mass% or more and 100 mass% or less with respect to the mass of a hydrous gel type polymer, An artificial ice for display comprising an absorbent resin having an average particle diameter of 2 mm or more and 10 mm or less and a logarithmic standard deviation value of the particle size distribution of 0 to 0.25.

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