JPH1135691A - Cutting of hydrous water absorbing and cross-linked polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for roughly crushing a massive hydrous water absorbing and crosslinked polymer rich in tackiness and elasticity. SOLUTION: A hydrous water absorbing and crosslinked polymer is cut by using a lubricant to thereby more maintain the structure of the hydrous water absorbing and crosslinked polymer and reduce the crushing of cells in the interior when cutting the hydrous water absorbing and crosslinked polymer; suppress the deterioration in cell content of the hydrous water absorbing and crosslinked polymer and afford a porous hydrous water absorbing and crosslinked polymer cut in a state of the many retained cells over the interior in a method for cutting the hydrous water absorbing and crosslinked polymer with a cutter having a rotating blade 13. hydrous water absorbing and crosslinked polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting a massive water-absorbent crosslinked polymer having high tackiness and elasticity.

[0002]

2. Description of the Related Art It is well known that a water-containing water-absorbent crosslinked polymer can be obtained by subjecting a water-soluble ethylenically unsaturated monomer to aqueous solution polymerization in the presence of a trace amount of a crosslinking agent.
The semi-solid, highly elastic, hydrogel-like water-absorbent crosslinked polymer thus obtained is hardly used as it is, and after shredding to a dry powder through a drying / crushing step, a water-absorbing agent is obtained. Often used as.

In such a treatment, first, it is necessary that the bulk water-absorbent water-absorbent crosslinked polymer be cut into smaller pieces. Crushing the crosslinked polymer with a meat chopper, or crushing the water-absorbent crosslinked polymer obtained while polymerizing in a kneader, or shredding the hydrogel after polymerization by hand with scissors, It was crushed by a method such as cutting while pressing the annular cutting edge against the opposing roll.

[0004]

However, in the above-mentioned conventional method, when a water-containing water-absorbent crosslinked polymer obtained by aqueous solution polymerization is crushed by a meat chopper or a kneader,
Since the water-absorbent crosslinked polymer is kneaded, that is, crushed while being compressed, a strong mechanical external force acts on the water-absorbent crosslinked polymer, the crosslinked polymer chain is cut, and the amount of the water-soluble component is reduced. May increase. In particular, when the water-containing water-absorbent crosslinked polymer is a water-soluble ethylenically unsaturated monomer, which is obtained by polymerizing an aqueous solution in the presence of a crosslinking agent so as to contain bubbles, the water-containing water-absorbent crosslinked polymer is contained inside the water-containing water-absorbent crosslinked polymer Bubbles are crushed, the bubbles existing inside the hydrous water-absorbent crosslinked polymer after crushing are reduced, and when attention is paid to the characteristics of a water-absorbing agent obtained as a dry powder after a drying / crushing step, Decrease leads to a decrease in specific surface area,
The liquid-guiding space required for the transfer of the aqueous liquid was not sufficiently secured, and the water-absorbing agent had to be reduced in liquid permeability and diffusivity of the aqueous liquid.

[0005] Therefore, the water-absorbing agent obtained by the method of passing through the conventional crushing step produces unfavorable results with respect to water-absorbing properties, such as a decrease in water absorption rate and water absorption capacity, and an increase in the amount of water-soluble components. Was.

[0006] On the other hand, in the case of shredding the water-absorbent water-absorbent crosslinked polymer with scissors by hand, it is possible to avoid crushing the bubbles contained in the hydrogel at the time of shredding, but the productivity is low and industrial production is low. Is unsuitable. Further, in this case, there is a problem that the cutting edge of the scissors becomes poor with time because the relatively large water-absorbent water-absorbent crosslinked polymer adheres to the cutting blades of the scissors. In the method of cutting while pressing the annular cutting edge against the opposing roll, pressing the water-absorbent crosslinked polymer against the opposing roll deforms the water-absorbent crosslinked polymer which is rich in elasticity. In addition, the water-containing water-absorbent crosslinked polymer wraps around and cannot be cut into a desired size, but also causes problems such as the inability to operate continuously.

The present inventors have conducted intensive studies to reduce the mechanical external force at the time of cutting a water-containing water-absorbent crosslinked polymer and to conduct a method capable of industrially producing continuously.
In the method of cutting the hydrous water-absorbent crosslinked polymer with a cutting machine equipped with a rotary blade, by cutting using a lubricant,
It is possible to cut the water-absorbent cross-linked polymer continuously without the trouble of adhesion of the water-absorbent cross-linked polymer to the rotary blade, and it is easy to obtain a water-absorbing agent having a high water-absorbing rate without increasing the amount of water-soluble components. This led to the completion of the present invention.

[0008]

In order to solve the above-mentioned problems, the method for cutting a water-absorbent water-absorbent crosslinked polymer according to the present invention is directed to a method for cutting a water-absorbent water-absorbent crosslinked polymer using a cutting machine equipped with a rotary blade. The cutting is performed using a lubricant.

The above water-containing water-absorbent crosslinked polymer is preferably obtained by aqueous polymerization of a water-soluble ethylenically unsaturated monomer in the presence of a crosslinking agent.

[0010] According to the above method, by cutting with a lubricant, the adhesion of the water-absorbent water-absorbent crosslinked polymer to the rotary blade is significantly reduced, and the cut surface becomes sharper. As a result, since the three-dimensional structure of the water-absorbent crosslinked polymer after cutting is more maintained, for example, when cutting the water-absorbent crosslinked polymer containing bubbles, The bubble to be cut can be cut into a desired size without being crushed. Furthermore, the water-absorbing agent obtained after drying is more maintained in the three-dimensional structure of the water-containing water-absorbent crosslinked polymer as compared with the conventional method in which the water-absorbent crosslinked polymer is disintegrated with a meat chopper or a kneader as it is. And the increase in the amount of water-soluble components can both be suppressed.

The above water-containing water-absorbent crosslinked polymer is preferably obtained by polymerizing a water-soluble ethylenically unsaturated monomer in an aqueous solution in the presence of a crosslinking agent so as to contain bubbles.

According to the above-mentioned method, the obtained water-absorbent water-absorbent crosslinked polymer contains more bubbles, and by cutting this by the method of the present invention, more bubbles are formed inside the hydrogel. While leaving the water-absorbent crosslinked polymer. Therefore, in the method of the present invention, since the water absorbing agent obtained after drying can secure a larger surface area due to the large content of bubbles, the water absorbing agent can obtain a higher water absorption capacity and a higher water absorption rate. .

As the water-soluble ethylenically unsaturated monomer, a water-absorbing agent having good physical properties such as water absorption rate and water absorption ratio can be obtained. Further, from the viewpoint of safety, acrylic acid and / or acrylic acid can be used. It is preferable to use an alkali metal salt.

In the above-mentioned method, secondary cross-linking may be further performed on the vicinity of the surface of the particulate water-absorbing agent which has been cut, dried and, if necessary, pulverized. As a result, the obtained particulate water-absorbing agent can have an increased water absorption under pressure while maintaining a high water absorption rate, a high water absorption, and a smaller amount of soluble components.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.

The method for cutting a water-absorbent water-absorbent crosslinked polymer of the present invention is characterized in that, in the method for cutting with a cutting machine equipped with a rotary blade, cutting is carried out using a lubricant. The water-containing water-absorbent crosslinked polymer is obtained by polymerizing a water-soluble unsaturated monomer capable of forming a water-containing water-absorbent crosslinked polymer by polymerization in the presence of a cross-linking agent, preferably so as to contain bubbles, or in reverse phase. It is obtained by turbid polymerization. After the obtained water-containing water-absorbent crosslinked polymer has passed through the cutting method of the present invention, it has undergone a drying / crushing step, has a high water absorption ratio, can be a water-absorbing agent having a small amount of soluble components and a high water absorption rate. .

In the method for cutting a water-absorbent water-absorbent crosslinked polymer of the present invention, by cutting the rotary blade of the present invention in a state in which a lubricant is adhered, the water-absorbent water-absorbent crosslinked polymer does not adhere to the rotary blade. It is possible to cut it while holding down its deformation,
It has the advantage that it can be cut without destroying the three-dimensional network structure of the water-containing water-absorbent crosslinked polymer.

The water-soluble ethylenically unsaturated monomer used for producing the water-containing water-absorbent crosslinked polymer of the present invention is not particularly limited as long as it is a water-soluble monomer capable of forming a water-containing water-absorbent crosslinked polymer by polymerization. Not something. As the water-soluble ethylenically unsaturated monomer, acrylic acid,
Methacrylic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acryloxyalkanesulfonic acid and alkali metal salts and ammonium salts thereof,
Examples thereof include N-vinyl-2-pyrrolidone, N-vinylacetamide, acrylamide, and alkoxy polyethylene glycol (meth) acrylate. One of these monomers may be used alone, or two or more thereof may be appropriately mixed. Among them, acrylic acid and alkali metal salts thereof are preferred from the viewpoint of good physical properties such as water absorption rate and water absorption ratio, and further from the viewpoint of safety.

The method for polymerizing the ethylenically unsaturated monomer is not particularly limited, and examples thereof include aqueous solution polymerization and reverse phase suspension polymerization.

Examples of the crosslinking agent include N, N'-methylenebisacrylamide, trimethylolpropane tri (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, triallylamine, tetraallyloxyethane, triallyl cyanurate. Such as a compound having two or more vinyl groups in the molecule, or ethylenediamine,
It is preferable to use a compound having two or more functional groups capable of reacting with a carboxyl group or a sulfonic acid group in the molecule, such as polyethyleneimine and (poly) ethylene glycol diglycidyl ether. The amount of the crosslinking agent used is 0.0% based on the total amount of the monomers in the reaction system.
001 to 10 mol%, preferably 0.001 to 1 mol%
It is sufficient if it falls within the range.

As a method for polymerizing the above-mentioned water-containing water-absorbent crosslinked polymer containing bubbles, a polymerization method in the presence of an azo-based initiator or a carbonate as a blowing agent (JP-A-5-237378, JP-A-5-237378, No. 7-185331), and a polymerization method in which a water-insoluble blowing agent such as pentane or trifluoroethane is dispersed in a monomer (US Pat. No. 53,531).
No. 28935, US Pat. No. 5,338,766), a polymerization method using a solid particulate foaming agent (WO 96/17884), a method of dispersing an inert gas in the presence of a surfactant, and the like. Can be used. Before the polymerization, if necessary, stirring is performed to mix the aqueous monomer solution. However, it is preferable that the aqueous monomer solution is allowed to stand without stirring during the polymerization.

The water content of the water-containing gel of the water-containing water-absorbent crosslinked polymer obtained as described above is generally 10 to 90% by weight.
And preferably in the range of 20 to 80% by weight. If the water content is less than 10% by weight, cutting may be difficult, and in the case of a water-containing water-absorbent crosslinked polymer containing bubbles, the bubbles may be crushed. The water content is 90% by weight.
If it is higher than this, it takes too much time for drying after cutting.

As the rotary blade used in the present invention, any one can be used as long as it has a rotating shaft such as a disk, a beveled shape, or a sword, and has a curved cutting surface. It is possible. As a cutting machine having such a rotary blade, for example, a cutting machine having a guillotine-type cutter as shown in FIG. 1; a cutting machine having a rotating blade which revolves while rotating as shown in FIG. 2; FIG. As a preferred specific example, a slicer such as a cutting machine provided with a pair of rotary blades having different axes that rotate while overlapping at least a part of the blades as shown in FIG.

The cutting machine shown in FIG. 1 has a circular box (12) provided on a machine base (11), and a rotary blade (13) is provided inside the box (12). In addition, a circular box (1
The pair of lids (2) is provided with a lubricant developing groove (16) having an inlet (15) into which the lubricant can be injected. The hydrated water-absorbent crosslinked polymer is introduced from the inlet (17), cut by the rotary blade (13) while being in contact with the lubricant, and discharged by the conveyor belt (18).

Similarly, FIG. 2 shows an example of a cutting machine having a rotating blade which revolves while rotating, which is preferably used in the present invention. The cutting machine has a box (22) provided on a machine base (21), and a rotary blade (24) is arranged in the box (22) so as to be able to rotate (24a) and revolve (24b).
A chute (2) on which a water-absorbent water-absorbent crosslinked polymer to be cut is placed on a lid plate (26) pivotally attached to the front opening of the box (22).
3) is protruding. A discharge conveyor (25) is provided rearward with one end thereof entering the box (22). A thin groove (28) is provided inside the cover plate (26), and a lubricant is added from an inlet (27),
The lubricant can be attached to the surface of the rotary blade (24).

FIG. 3 shows an example of a cutting machine having a pair of rotating blades, which are preferably used in the present invention, and have different axes which rotate while overlapping at least a part of the blades. The axis (32a) faces the other axis (32b),
Each of the shafts (32) has a plurality of rotary blades (31). The rotating blade (31a) is a pair of rotating blades (31a) opposed to each other.
The shaft (32b) is provided with a groove (33) through which the tip of the rotary blade (31a) can enter. The hydrated water-absorbent crosslinked polymer is placed on a feed conveyor (34), and the opposed rotary blade (3
It is cut while passing under the spray of the lubricant between 1) and is transferred to the discharge conveyor (35).

In the present invention, the rotation speed of the rotary blade and the feeding speed of the water-containing water-absorbent crosslinked polymer may be controlled in accordance with the desired size of the water-absorbent water-absorbent crosslinked polymer after cutting. The size of the water-containing water-absorbent crosslinked polymer after cutting is, for example, usually 1 if considering the subsequent drying load.
mm to 50 mm, preferably about 2 mm to 30 mm.

The materials used for the rotary blade used in the present invention include carbon steel, Swedish steel, bearing steel, ceramics, spring steel, powdered high-speed steel, alloy tool steel, cemented carbide,
Materials such as high-speed steel, stainless steel, stainless steel, and ferrotics can be used. These materials may be surface-treated before use. Examples of the surface treatment method of the rotary blade include carburizing, nitriding, diclonal treatment, atomroy treatment, Nidax treatment, Teflon coating, Tefloc, tungsten spraying, hard chrome plating, and ceramic spraying.

In the present invention, the lubricant to be used is not particularly limited as long as it can prevent the water-containing water-absorbent crosslinked polymer from adhering to the rotary blade. Water; a hydrophilic organic solvent such as alcohol and acetone; Heavy oil, hexane,
Organic solvents such as kerosene; various surfactants; Suitable surfactants include, for example, anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Specific examples of the anionic surfactant include, for example, fatty acid salts such as mixed fatty acid sodium soap, semi-hardened cattle fatty acid sodium soap, sodium stearate soap, potassium oleate soap, sodium oleate soap, and castor oil potassium soap. Alkyl sulfate salts such as sodium lauryl sulfate, ammonium lauryl sulfate, higher alcohol sodium sulfate and triethanolamine lauryl sulfate; alkyl benzene sulfonates such as sodium dodecylbenzene sulfonate; alkyl naphthalene sulfonates such as sodium alkyl naphthalene sulfonate;
Alkyl sulfosuccinates such as sodium dialkyl sulfosuccinate; alkyl diphenyl ether disulfonates such as sodium alkyl diphenyl ether disulfonate; alkyl phosphates such as potassium alkyl phosphate; sodium polyoxyethylene lauryl ether sulfate; sodium polyoxyethylene alkyl ether sulfate Polyoxyethylene alkyl (or alkylallyl) sulfate salts such as sodium polyoxyethylene alkyl ether triethanolamine sulfate and polyoxyethylene alkyl phenyl ether sulfate; special reaction type anionic surfactants; special carboxylic acid type surfactants; β
-Naphthalene sulfonic acid formalin condensate such as sodium salt of naphthalene sulfonic acid formalin condensate, sodium salt of special aromatic sulfonic acid formalin condensate; special polycarboxylic acid type polymer surfactant; polyoxyethylene alkyl phosphate, etc. However, there is no particular limitation. As nonionic surfactants,
Specifically, for example, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether such as polyoxyethylene higher alcohol ether, polyoxyethylene nonylphenyl Polyoxyethylene alkylaryl ethers such as ethers; polyoxyethylene derivatives; sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate, sorbitan Sorbitan fatty acid esters such as distearate; polyoxyethylene sorbitan monolaurate, polyoxyethylene Polyoxyethylene sorbitan fatty acid esters such as bitane monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate; polyoxyethylene tetraoleate Polyoxyethylene sorbitol fatty acid esters such as sorbitol; glycerin fatty acid esters such as glycerol monostearate, glycerol monooleate and self-emulsifying glyrosale monostearate; polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distear Polyoxyethylene fatty acid esters such as polyethylene glycol monooleate; Alkoxy polyoxyethylene alkyl amines, polyoxyethylene hardened castor oil; but alkyl alkanol amides, but is not particularly limited. Specific examples of the cationic surfactant and the double-sided surfactant include, for example, alkylamine salts such as coconutamine acetate and stearylamine acetate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride,
Quaternary ammonium salts such as cetyltrimethylammonium chloride, distearyldimethylammonium chloride, and alkylbenzyldimethylammonium chloride; alkylbetaines such as laurylbetaine, stearylbetaine, laurylcarboxymethylhydroxyethylimidazoliniumbetaine; lauryldimethylamine oxide and the like Amine oxide; and the like, but are not particularly limited thereto. Further, as a more suitable surfactant, there is a fluorine-based surfactant. By using the fluorine-based surfactant, the adhesion of the water-containing crosslinked polymer to the rotary blade can be further reduced. The fluorine-based surfactant used in the present invention is not particularly limited, and includes various conventionally known ones.For example, a hydrogen-containing lipophilic group of a general surfactant is replaced with fluorine. Is a perfluoroalkyl group,
Those having significantly increased surface activity are preferred. When the hydrophilic group of the fluorinated surfactant is changed, there are four types of anionic type, nonionic type, cationic type and amphoteric type,
In the case of a hydrophobic group, a fluorocarbon chain having the same structure is often used. Further, the carbon chain serving as the hydrophobic group may be straight-chain or branched. Specific examples of the fluorine-based surfactant include, for example, fluoroalkyl (C2-
C10) Carboxylic acid, disodium N-perfluorooctylsulfonylglutamate, 3- [fluoroalkyl (C6-C11) oxy] -1-alkyl (C3-C4)
Sodium sulfonate, 3- [ω-fluoroalkanoyl (C6 -C8) -N-ethylamino] -1-propanesulfonic acid sodium, N- [3- (perfluorooctylsulfonamido) propyl] -N, N'- Dimethyl-N-carboxymethylene ammonium betaine, fluoroalkyl (C11 -C20) carboxylic acid, perfluoroalkyl carboxylic acid (C7 -C13), perfluorooctylsulfonic acid diethanolamide, perfluoroalkyl (C4 -C12) sulfonate ( Li, K, Na),
N-propyl-N- (2-hydroxyethyl) perfluorooctylsulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N
-Ethylsulfonylglycine salt (K), bisphosphate (N
-Perfluorooctylsulfonyl-N-ethylaminoethyl), monoperfluoroalkyl (C6-C16) ethyl phosphate, perfluoroalkyl quaternary ammonium iodide (trade name: Florard FC-135,
Sumitomo 3M Co., Ltd., cationic fluorine-based surfactant), perfluoroalkyl alkoxylate (trade name: Florard FC-171, Sumitomo 3M Co., nonionic fluorinated surfactant), potassium perfluoroalkyl sulfonate Salt (trade name; Florard FC)
-95 and Florad FC-98, manufactured by Sumitomo 3M Limited, anionic fluorine-based surfactants), but are not particularly limited. These lubricants may be used alone or in combination of two or more.

In consideration of the water absorbing properties of the obtained water absorbing agent, water and / or a hydrophilic organic solvent or an aqueous solution of a surfactant is more preferable. By doing this,
It becomes possible to mold the water-containing water-absorbent crosslinked polymer into a desired size, and the drying of the water-containing water-absorbent crosslinked polymer can be facilitated and speeded up.

The amount of the lubricant used in the present invention is 0.01 to 100 parts by weight of the water-containing water-absorbent crosslinked polymer.
Preferably in the range of 100 parts by weight to 100 parts by weight,
More preferably, it is in the range of 0.03 parts by weight to 20 parts by weight. If the amount of the lubricant is less than 0.01 part by weight, the lubricant may be kneaded during cutting, which is not preferable. On the other hand, if it exceeds 100 parts by weight, the effect corresponding to the added amount may not be obtained, and it is not economical.

In the present invention, the cut water-absorbent water-absorbent crosslinked polymer can be converted into a particulate water-absorbing agent through a drying / pulverizing step, if necessary. It is preferable to increase the crosslink density near the surface by subjecting the surface to secondary crosslinking with an agent. By treating the water-absorbing agent obtained by the method of the present invention with a surface cross-linking agent, the liquid-permeability, water-absorbing speed, water-absorption ratio under pressure, and liquid-permeability of the water-absorbing agent are further improved.

Specific examples of the surface crosslinking agent suitably used in the present invention include, for example, (poly) ethylene glycol, diethylene glycol, (poly) propylene glycol, triethylene glycol, tetraethylene glycol, 1,3- Propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, (poly) glycerin, 2-butene-1,4-diol, 1,4-butanediol, 1,5-pentanediol , 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-
Polyhydric alcohols such as oxypropylene block copolymer, pentaerythritol, sorbitol, polyvinyl alcohol, glucose, mannitol, sucrose, glucose; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol Polyhydric epoxy compounds such as polyglycidyl ether, polyglycerol polyglycidyl ether and (poly) propylene glycol diglycidyl ether; polyhydric amine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and polyethyleneimine Polyvalent isocyanates such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; Compounds; polyvalent 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-
On, 4-hydroxymethyl-1,3-dioxolane-
2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-
Alkylene carbonate compounds such as 1,3-dioxan-2-one and 1,3-dioxopan-2-one; haloepoxy compounds such as epichlorohydrin, epibromohydrin and α-methylepichlorohydrin; zinc, calcium And polyvalent metal compounds such as hydroxides and chlorides of polyvalent metals such as magnesium, aluminum, iron and zirconium; and the like, but are not particularly limited. These surface cross-linking agents may be used alone, or two or more of them may be appropriately mixed and used.

The water-absorbent water-absorbent crosslinked polymer cut according to one embodiment of the present invention has a large number of air bubbles (pores) formed throughout the inside thereof, and the water-absorbent water-absorbent crosslinked polymer is crushed without breaking the air bubbles. Can be obtained as a union.

The water-containing water-absorbent crosslinked polymer after the above-mentioned cutting is
Since it is porous with many bubbles inside, it has excellent water permeability and diffusion properties of aqueous liquids through a drying step and a pulverization step if necessary, and the water absorption rate and water retention ability etc. are improved by capillary action Water absorbing agent.

As described above, the structure of the water-absorbent water-absorbent crosslinked polymer can be further improved by cutting the water-absorbent water-absorbent crosslinked polymer by a cutting machine equipped with a rotary blade using a lubricant by the cutting method of the present invention. Maintained, it is possible to cut to a desired size while reducing crushing of internal bubbles when cutting the water-containing water-absorbent crosslinked polymer and suppressing a decrease in the bubble content of the water-containing water-absorbent crosslinked polymer. As a result, a water-absorbing agent having excellent water-absorbing performance can be stably and easily obtained.

The water-absorbing agent obtained through the cutting method of the present invention has excellent water-absorbing performance, and can be used, for example, in sanitary materials (body fluid-absorbing articles) such as paper diapers, sanitary napkins, incontinence pads, wound protecting materials, wound healing materials and the like. ); Absorbent articles such as urine for pets; Construction materials such as water-retaining materials for construction and soil, waterproof materials, packing materials, gel blisters, etc .; Food products such as drip-absorbing materials, freshness-retaining materials, and cool-keeping materials ; Oil-water separation materials, dew condensation prevention materials,
Various industrial articles such as coagulants; agricultural and horticultural articles such as water retention materials such as plants and soil;

[0038]

EXAMPLES The method for cutting a water-containing water-absorbent crosslinked polymer of the present invention will be specifically described based on the following examples, but the present invention is not limited to these examples. In the following description, “part” indicates “part by weight” and “%” indicates “% by weight”.

First, the methods for measuring the physical properties of the obtained water absorbing agent will be described below.

(A) Water Absorption Ratio About 0.2 g of a water absorbing agent was accurately weighed, placed in a 5 cm square non-woven tea bag, and sealed by heat sealing. This tea bag was immersed in artificial urine at room temperature.
One hour later, the tea bag was pulled out, and the liquid was drained at 250 G for 3 minutes using a centrifuge. Then, the weight W1 (g) of the tea bag was measured. Separately, the same operation was performed without enclosing the water-absorbing agent in the tea bag, and the weight W0 (g) of the tea bag at that time was determined as a blank.
The water absorption capacity was calculated based on the following equation.

Water absorption capacity (g / g) = (W1 (g) -W0)
(G) -Weight of water-absorbent resin (g)) / Weight of water-absorbent resin (g) The composition of the above-mentioned artificial urine and the compounding amount thereof are as follows.

Composition of artificial urine Amount of each composition Sodium sulfate 0.200% Potassium chloride 0.200% Magnesium chloride hexahydrate 0.050% Calcium chloride dihydrate 0.025% Ammonium dihydrogen phosphate 0 0.035% diammonium hydrogen phosphate 0.015% deionized water 99.475% (b) Amount of water-soluble component 0.5 g of a water-absorbing agent is dispersed in 1000 ml of deionized water, stirred for 16 hours, and then filtered through a filter paper. did. Then, the obtained filtrate was subjected to colloid titration using a cationic colloid reagent, and the amount of water-soluble component (%) of the water absorbing agent was determined by measuring the amount of colloid of the water absorbing agent dispersed in the filtrate.

(C) Measurement of Water Absorption Rate 1.0 g of a water absorbing agent was placed in a bottomed cylindrical polypropylene cup having an inner diameter of 50 mm and a height of 70 mm. Next, 20 g of artificial urine was poured into the cup, and the artificial urine was uniformly absorbed by the water absorbing agent. Then, the time from when the artificial urine was poured until all the artificial urine gelled and the artificial urine was completely absorbed by the water absorbing agent and became invisible was measured. The measurement was repeated three times, and the average value was taken as the water absorption rate (second).

Example 1 306 parts of acrylic acid, 37% sodium acrylate 32
30 parts, polyethylene glycol (n = 8) diacrylate 12 parts, polyoxyethylene sorbitan monostearate (trade name: Reodol TW-S120, manufactured by Kao Corporation) 0.3 part, pure water 1330 parts and 10% persulfuric acid A monomer aqueous solution containing 20 parts of a sodium aqueous solution was prepared. The monomer aqueous solution and nitrogen were fluid-mixed using Whip Auto Z manufactured by Aikosha Co., Ltd., and bubbles of nitrogen gas were dispersed in the monomer aqueous solution to prepare a monomer aqueous solution in which bubbles were dispersed. 100 parts of a 2% by weight aqueous solution of sulfurous acid was added to the bubble-containing monomer aqueous solution, and polymerization was immediately started. Subsequently, the temperature is 25 to 95 ° C. with the air bubbles dispersed.
For 1 hour.

The sponge-like water-absorbent crosslinked polymer containing a large amount of air bubbles therein was obtained by using the cut slicer shown in FIG. 1 and a 50% aqueous ethanol solution was used as a lubricant. The polymer was cut into 20 mm square while being added at a ratio of 1% to the polymer.
Drying was performed in a hot air dryer at 60 ° C. for 90 minutes. The dried product was pulverized with a tabletop pulverizer, and the material passed through a sieve having an opening of 850 μm was fractionated to obtain a water absorbing agent (1) having an average particle size of 280 μm. The obtained water-absorbing agent (1) had a water absorption capacity, a water absorption rate and a water-soluble component amount of 50.7 g / g, 15 seconds and 9.9, respectively.
5%.

Example 2 0.03 parts of ethylene glycol diglycidyl ether and propylene glycol 1 were added to 100 parts of the water absorbing agent (1).
Part, pure water 3 parts, and an aqueous liquid containing a compound having a plurality of functional groups capable of reacting with a carboxyl group consisting of 2 parts of isopropanol, and then heated at 185 ° C. for 60 minutes. Water absorbing agent (2) was obtained. The water absorption rate, water absorption capacity, and water-soluble component amount of the obtained water-absorbing agent (2) were 8 seconds, 37.7 g / g, and 8.5%, respectively.

Comparative Example 1 The sponge-shaped water-absorbent crosslinked polymer (1) obtained in Example 1 was subjected to the same cutting treatment as in Example 1 without adding a 50% aqueous ethanol solution as a lubricant. However, the water-absorbent water-absorbent crosslinked polymer (1) was not cut, and the water-absorbent crosslinked polymer adhered to the rotary blade, and the cutting machine stopped.

[0048]

As described above, the method for cutting the water-containing water-absorbent crosslinked polymer of the present invention comprises the steps of preparing a water-soluble ethylenically unsaturated monomer, preferably acrylic acid or / and an alkali metal acrylate, in the presence of a crosslinking agent. Preferably, the method is a method in which a water-absorbent water-absorbent crosslinked polymer obtained by aqueous solution polymerization containing bubbles is cut by a cutting machine equipped with a rotary blade using a lubricant.

Therefore, in the above method, the gel structure is more maintained when the hydrated water-absorbent crosslinked polymer is cut, and the bubbles contained in the hydrated water-absorbent crosslinked polymer are crushed when the hydrated water-absorbent crosslinked polymer is cut. Can be suppressed.

For this reason, in the water absorbing agent obtained by the above-mentioned method, it is possible to maintain an excellent water absorption capacity and a smaller amount of soluble components.

[Brief description of the drawings]

FIG. 1 is a perspective view of a slicer showing one embodiment of the present invention.

FIG. 2 is a perspective view of a slicer showing one embodiment of the present invention.

FIG. 3 is a perspective view of a slicer showing one embodiment of the present invention.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akito Yano 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo

Claims (3)

[Claims] 1. A method for cutting a water-absorbent water-absorbent crosslinked polymer, wherein the method comprises a step of cutting using a lubricant. 2. The method for cutting a water-containing water-absorbent crosslinked polymer according to claim 1, wherein the cutting is carried out with a lubricant attached to the rotary blade. 3. The water-containing water-absorbent crosslinked polymer is obtained by polymerizing a water-soluble ethylenically unsaturated monomer in an aqueous solution in the presence of a crosslinking agent so as to contain bubbles. For cutting the water-containing water-absorbent crosslinked polymer.