JP4920182B2 - Method for producing water absorbent resin particles - Google Patents

Description

The present invention relates to the production how the water absorbent resin particles, particularly, in the process of manufacturing the water-absorbing resin particles, cutting the continuous sheet of high density hydrous cross-linked polymer manufactured in advance a sheet-like water-absorbent resin and Fritsch, after obtaining a particulate hydrogel, dried directed to a way of producing a water-absorbent resin particles.

As a technology for producing water-absorbent resin particles widely used in absorbent materials for absorbent products such as disposable diapers, a water-absorbent resin-containing water-containing gel sheet is manufactured, and then the water-containing gel sheet is crushed to obtain a water-containing gel. Techniques for producing particles are known.
Patent Document 1 proposes a method for continuously producing a high-concentration hydrous gel sheet by supplying an aqueous solution containing a monomer component such as acrylic acid onto an endless belt and polymerizing it in a stationary state. A technique for obtaining hydrogel particles by pulverizing a high-concentration hydrous gel sheet with a shearing type coarse crusher or a cutting / shearing mill is also shown. As a crushing device, a screen type crushing device having a screen and crushing by shearing between a fixed blade and a rotary blade is considered preferable. The obtained hydrogel particles are dried or pulverized to obtain water-absorbing resin particles. The high-concentration hydrous gel sheet does not become a flat and smooth sheet, but has a form in which the thickness varies depending on the location due to the expansion and contraction of the foam due to boiling during polymerization, and the waviness and undulation occur in the thickness direction. Yes. The high-concentration hydrous gel sheet of such a form is said to have an advantage that it can be easily crushed and the water-absorbent resin particles can be easily produced.

In Patent Document 2, a sheet of a water-soluble polymer gel is cut into a strip shape with a pair of roller-type cutters, and then cut in a direction perpendicular to the roller-type cutter with a rotary blade and a fixed blade. A technique for producing a water-soluble polymer gel in the form of a liquid is shown. The fixed blade is disposed directly under the strip-shaped sheet discharged from the pair of roller-type cutters. The rotary blade is disposed along the axial direction on the outer periphery of the cylindrical rotary body, and the rotary blade sandwiches the strip-shaped sheet between the rotary blade and the fixed blade to cut the rotary blade. It is said that even a hard polymer gel can be easily segmented and adhesion between the strips hardly occurs.
In Patent Document 3, a continuous sheet of a water-containing polymer gel is run, and a continuous sheet of a continuous sheet is formed with a disk-shaped cutter provided in the cutting roll in a nip gap between a cutting roll and an opposing roll arranged above and below the continuous sheet. Cut in the length direction, cut in the width direction, and cut with a rectangular plate-shaped rotary blade provided in the same cutting roll in the axial direction to scrape the continuous sheet at regular intervals in the length direction. Techniques for obtaining rectangular gel pieces are shown. It is also described that water-absorbent resin particles are obtained by finely pulverizing the obtained gel piece. Even if it is a flexible polymer gel sheet, it is said that a gel piece can be obtained satisfactorily without adhering to the cutting blade.
JP 2002-212204 A Japanese Patent Laid-Open No. 61-110510 EP 0 847 443 B1 specification

The conventional water gel sheet cutting technology cannot sufficiently prevent the water gel from adhering to the cutting blade, etc., and the work is interrupted due to the water gel sticking and clogging phenomenon, or the work of frequently removing the adhering material is performed. I had to do something.
In particular, in the case of a high-concentration hydrous gel sheet as disclosed in Patent Document 1, as described above, there are variations in thickness, waviness, undulation, etc. Or the cut pieces that have been cut easily reattach.
In the technique of Patent Document 1, a high-concentration hydrous gel sheet is crushed using a shearing type crusher or a cutting / shearing mill, but a continuously produced high-concentration hydrogel sheet is crushed immediately and continuously. If it tries to crush by supplying to an apparatus, it will be easy to generate | occur | produce and obstruct | occlude on the screen etc. in a crushing apparatus also because a high concentration hydrous gel sheet is a high temperature state immediately after manufacture.

In the cutting technique of Patent Document 2, a strip-shaped sheet cut by a pair of roller cutters falls directly above a rotating body to which a rotating blade is attached. Therefore, the thin sheet cut by the rotating blade and the fixed blade is used. The piece tends to remain attached to the surface of the rotating body. If strips accumulate on the outer peripheral surface of the rotating body, the cutting operation cannot be performed.
Patent Document 2 proposes that the gel sheet is cooled to about 10 to 30 ° C. to lower the temperature in order to prevent adhesion. However, a long distance from the gel sheet manufacturing apparatus to the cutting apparatus is required to ensure that the gel sheet, which may be in a high temperature state near 100 ° C. immediately after manufacture, is sufficiently cooled before being sent to the cutting apparatus. It is necessary to travel, add a cooling device in the travel route, or slow down the travel speed to ensure the cooling time, which increases the equipment cost and decreases the production efficiency.

In the cutting technique of Patent Document 3, since the plate-like rotary blade is cut into the continuous sheet and scraped off at a nip gap between the rollers, it is difficult to reliably cut the entire thickness of the continuous sheet. In particular, in the case of a high-concentration hydrous gel sheet with thickness variations, undulations, and undulations, cutting is difficult. Since the continuous sheet is run while being nipped, i.e., sandwiched between the cutting roller and the opposing roller, the continuous sheet tends to adhere to the surfaces of the cutting roller and the opposing roller. In particular, the cut gel piece tends to adhere to the opposing roller.
An object of the present invention is to efficiently cut a continuous sheet of high-concentration water-containing gel suitable for the production of the above-described high-performance water-absorbent resin particles without causing adhesion to a cutting blade and the like, and then crushing work It is also possible to obtain water-containing gel particles having excellent quality performance and efficiently producing water-absorbing resin particles .

The method for producing water-containing gel particles according to the present invention is a method for producing water-containing gel particles from a high-concentration water-containing gel sheet, and a continuous sheet of a high-concentration water-containing gel-like crosslinked polymer having a solid content concentration of 50 to 80% by weight. While traveling in the length direction, the step (a) of obtaining a cut piece by cutting every 10 to 100 cm in the length direction of the continuous sheet and the cut piece obtained in the previous step (a) are continuously and continuously solved. The hydrated gel is supplied to the crushing device, and is continuously crushed and discharged under the condition that the supply amount of the cut pieces and the crushing and discharging capability of the continuous crushing device are the supply amount ≦ the crushing and discharging capability. look including the step (b) to obtain particles, the step (a), the cutting means for cutting the continuous sheet, supplying water, a medium selected from the group consisting of hot water and steam (a-3) the including.
[High concentration hydrogel sheet]
Basically, a technique common to the technique for producing a high-concentration water-containing gel-like cross-linked polymer sheet employed in the usual technique for producing water-absorbent resin particles can be applied. Among the techniques disclosed in Japanese Patent Application Laid-Open No. 2002-212204, a technique for producing a high-concentration hydrous gel sheet by a method in which a monomer aqueous solution supplied onto an endless belt is continuously allowed to stand and polymerize can be applied.

<Aqueous monomer solution>
In addition to the monomer component, an unsaturated monomer component such as an internal crosslinking agent, a polymerization initiator, and the like are blended in the monomer aqueous solution used for the production of the high-concentration hydrogel sheet.
Monomer components include (meth) acrylic acid, (anhydrous) maleic acid, itaconic acid, cinnamic acid, vinyl sulfonic acid, allyl toluene sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide Anionic unsaturated monomers such as 2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2-hydroxyethyl (meth) acryloyl phosphate, and the like Salt; mercaptan group-containing unsaturated monomer; phenolic hydroxyl group-containing unsaturated monomer; amide group-containing unsaturated group such as (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide Monomer; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethyl Aminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) amino group-containing unsaturated monomer acrylamide. These monomers may be used singly or may be used in combination of two or more, but acrylic acid and / or a salt thereof (for example, sodium) from the viewpoint of performance and cost of the resulting water-absorbent resin It is desirable to use a salt of lithium, potassium, ammonium, amines, etc., among which a sodium salt is preferable from the viewpoint of cost) as a main component. Preferably, acrylic acid and / or a salt thereof is 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, based on all monomer components.

  As the internal cross-linking agent, it is preferable to copolymerize or react a compound having two or more polymerizable unsaturated groups or two or more reactive groups in one molecule as the internal cross-linking agent. Specific examples of the internal crosslinking agent include, for example, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meta) ) Acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol hexa (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine , Poly (meth) allyloxyalkane, (poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, polyethylene Recall, propylene glycol, glycerol, pentaerythritol, ethylenediamine, ethylene carbonate, propylene carbonate, and glycidyl (meth) acrylate.

The amount of the internal crosslinking agent used is preferably in the range of 0.005 mol% to 2 mol%, and in the range of 0.02 mol% to 0.5 mol%, relative to the monomer component. It is more preferable that the content be in the range of 0.04 mol% to 0.2 mol%. When the amount of the internal cross-linking agent used is less than 0.005 mol% and more than 2 mol%, sufficient absorption characteristics may not be obtained.
The polymerization initiator is not particularly limited, and is a thermal decomposition type initiator (for example, persulfate: sodium persulfate, potassium persulfate, ammonium persulfate; peroxide: hydrogen peroxide, t-butyl peroxide, methyl ethyl ketone peroxide). Oxide; azo compound: azonitrile compound, azoamidine compound, cyclic azoamidine compound, azoamide compound, alkylazo compound, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (2-imidazoline- 2-yl) propane] dihydrochloride), photodegradable initiators (for example, benzoin derivatives, benzyl derivatives, acetophenone derivatives, benzophenone derivatives, azo compounds) and the like can be used. Persulfate is preferred because of its cost and ability to reduce residual monomer. It is also a preferable method to use a photolytic initiator and ultraviolet rays. More preferably, a photodegradable initiator and a thermal decomposable initiator are used in combination.

The concentration of the monomer component in the aqueous monomer solution is not particularly limited, but is preferably 30% by weight or more, more preferably 35% by weight or more, further preferably 40% by weight or more, and further preferably 45% by weight or more. More preferably, it is 50% by weight or more, more preferably 55% by weight or more, further preferably 30 to 70% by weight, more preferably 35 to 60% by weight, and further preferably 40 to 60% by weight. If it is less than 30% by weight, the productivity is low, and if it exceeds 70% by weight, the absorption capacity is low.
The reaction system includes various foaming agents such as carbonic acid (hydrogen) salt, carbon dioxide, azo compound, inert organic solvent; starch / cellulose, starch / cellulose derivatives, polyvinyl alcohol, polyacrylic acid (salt), polyacrylic acid (Salts) Hydrophilic polymers such as crosslinked bodies; various surfactants; chelating agents; chain transfer agents such as hypophosphorous acid (salts) may be added. Moreover, you may add inorganic powder.

<Continuous stationary polymerization>
The usual continuous static polymerization technique used for the manufacturing technique of water-absorbent resin particles can be applied. For example, the technique disclosed in Patent Document 1 can be applied.
The structure of the endless belt or other polymerization apparatus employs a technique common to normal continuous stationary polymerization. The polymerization apparatus can include a heating / cooling mechanism, an ultraviolet irradiation apparatus, a decompression apparatus, and the like.
The polymerization is usually carried out under normal pressure, but it is also preferred to carry out the distillation while distilling off water under reduced pressure in order to lower the boiling temperature of the polymerization system. For ease of operation, etc., it is more preferably carried out under normal pressure.

The temperature of the monomer supplied to the polymerization is not particularly limited, but is usually 50 ° C. or higher, preferably 60 ° C. or higher, more preferably 70 ° C. or higher, more preferably 80 ° C. or higher, more preferably 90 ° C. or higher, More preferably, it is 80 degreeC-105 degreeC, Most preferably, it is 90-100 degreeC. If it is less than 50 ° C., not only the productivity is lowered due to the prolonged induction period and polymerization time, but also the physical properties of the water-absorbent resin are lowered. The polymerization time refers to the time from when the monomer aqueous solution is supplied and the polymerization start conditions are satisfied to the peak temperature.
The polymerization initiation temperature is usually 50 ° C. or higher, preferably 60 ° C. or higher, more preferably 70 ° C. or higher, more preferably 80 ° C. or higher, more preferably 90 ° C. or higher, more preferably 80 ° C. to 105 ° C., most preferably 90-100 ° C. When the polymerization initiation temperature is less than 50 ° C., not only the productivity is lowered due to the extension of the induction period and the polymerization time, but the physical properties of the water absorbent resin are also lowered. When the polymerization start temperature exceeds 105 ° C., foaming and stretching may not be sufficiently performed. The polymerization initiation temperature can be observed by the cloudiness of the aqueous monomer solution, the increase in viscosity, the increase in temperature, and the like.

The maximum temperature reached during the polymerization is not particularly limited, but is preferably 150 ° C. or lower, more preferably 140 ° C. or lower, more preferably 130 ° C. or lower, more preferably 120 ° C. or lower, more preferably 115 ° C. or lower. If it exceeds 150 ° C., it is not preferable in that the physical properties of the polymer or water-containing gel and water-absorbing resin particles obtained are significantly reduced.
The difference ΔT between the polymerization initiation temperature and the highest temperature reached during polymerization is preferably 70 ° C. or less, more preferably 60 ° C. or less, further preferably 50 ° C. or less, more preferably 40 ° C. or less, and further preferably 30 ° C. Hereinafter, it is most preferably 25 ° C. or lower. When ΔT is higher than 70 ° C., it is not preferable in that the physical properties of the polymer, the water-containing gel and the water-absorbing resin particles obtained are lowered.

The polymerization time is not particularly limited, but is preferably 5 minutes or less, more preferably 3 minutes or less, more preferably less than 3 minutes, more preferably 2 minutes or less, more preferably 1 minute or less. When it exceeds 5 minutes, it is not preferable at the point that productivity falls.
In this polymerization method, after the polymerization starts, the temperature of the system rises rapidly and reaches a boiling point at a low polymerization rate, for example, 10 to 20 mol%, and water vapor is emitted to proceed the polymerization while increasing the solid content concentration. Causes expansion and contraction of foam during polymerization. The water vapor pressure due to boiling during polymerization causes the polymerization system to foam and increase the surface area, thereby causing the vaporization of water vapor and subsequent shrinkage. The water-containing gel sheet in such a form has good peelability from an endless belt or the like as a polymerization vessel, and can be easily crushed into particles.

The expansion ratio of the hydrogel sheet during the polymerization is preferably 2 times or more, more preferably 3 times or more, more preferably 5 times or more, more preferably 10 times or more, more preferably 20 times or more. At the time of expansion, since the polymerization system is stretched, the polymerization proceeds while being stretched.
High-performance water-containing gel or water-absorbing resin particles can be obtained by polymerizing at a high temperature from the start of the polymerization. In the polymerization under normal pressure, it is preferable that the temperature is already 100 ° C. or higher when the polymerization rate is 40 mol%, and the temperature is still 100 ° C. or higher even when the polymerization rate is 50 mol%. When the polymerization rate is 30 mol%, the temperature is already 100 ° C or higher, and even when the polymerization rate is 50 mol%, the polymerization is more preferably 100 ° C or higher. The polymerization is most preferably at a temperature of 100 ° C. or higher when the polymerization rate is 20 mol% and at a temperature of 100 ° C. or higher even when the polymerization rate is 50 mol%. In the case of the vacuum polymerization, it is preferable that the boiling temperature is already reached when the polymerization rate is 40 mol%, and that the boiling temperature is still obtained even when the polymerization rate is 50 mol%. It is more preferable that the boiling point is already at the boiling point when the polymerization rate is 30 mol%, and the boiling point is still higher even when the polymerization rate is 50 mol%, and the boiling point is already reached when the polymerization rate is 20 mol%. Most preferred is polymerization such that the mole temperature is still at the boiling temperature.

The ratio (concentration ratio) between the solid content concentration of the hydrogel produced by polymerization and the solid content concentration of the monomer aqueous solution is preferably 1.10 or more, more preferably 1.15 or more, and even more preferably 1.20 or more. Furthermore, it is desirable to perform polymerization while evaporating moisture so that the ratio is 1.25 or more. When the concentration ratio is less than 1.10, it cannot be said that the heat of polymerization is sufficient. Here, the solid content of the monomer aqueous solution is a monomer and other additives, and does not include water or a solvent.
The produced hydrogel sheet has a solid content concentration of 50 wt% to 80 wt%, more preferably 52 wt% to 75 wt%, and still more preferably 55 wt% to 70 wt%. When the solid content concentration is too high, the performance is decreased, that is, the absorption capacity is decreased and the soluble content is increased. If the solid content concentration is too low, the burden of drying in the subsequent process increases.

[Continuous sheet]
The continuous sheet of the high-concentration hydrogel crosslinked polymer produced as described above has different dimensions depending on the production apparatus and production conditions. Usually, the width of the continuous sheet is from 10 cm to a maximum of 3 m. The thickness of the continuous sheet varies considerably depending on the location, but falls within the range of 1 to 50 mm. Moreover, the continuous sheet is not a flat and smooth sheet form, but has undulations and undulations.
The continuous sheet is fed in the length direction and supplied to the cutting process. The running speed of the continuous sheet is limited by the production conditions of the high-concentration hydrous gel sheet, but is usually set to 2 to 20 m / min.

The continuous sheet immediately after being produced by the above-mentioned continuous stationary polymerization is usually in a high temperature state of about 60 ° C. to 100 ° C. In the present invention, this high temperature continuous sheet can be supplied to the cutting step. . It is also possible to supply the cutting process at a high temperature of 70 ° C. or higher or 80 ° C. or higher.
(Cut piece)
Depending on the intended use and required performance of the hydrogel particles or the characteristics of the high-concentration hydrogel sheet, the dimensional conditions of the cut pieces produced from the continuous sheet differ. In particular, it is desirable that the size and shape be suitable for a crushing process for producing hydrogel particles. It is desirable that the supply by continuous charging into the continuous crushing apparatus can be performed satisfactorily.

The shape of the cut piece is generally rectangular. However, depending on the cutting method, the shape may not be a strict rectangle, but may be a parallelogram or a diamond close to a rectangle. The outer periphery is usually configured with a straight line, but may include a curved line.
As for the size of the cut piece, the length on the long side can be set to 10 to 300 cm, preferably 10 to 200 cm, more preferably 10 to 100 cm. The length on the short side can be set to 10 to 100 cm, preferably 10 to 50 cm.
Moreover, although it changes also with the continuous crushing apparatuses to be used, if the width | variety of a continuous sheet is 10-300 cm, for example, Preferably it is 10-200 cm, More preferably, it is 10-100 cm. A cut piece can also be obtained by cutting only the vertical direction for each fixed dimension.

[Cutting in the length direction]
When manufacturing a cut piece from a continuous sheet, if the width of the continuous sheet is narrow, the target cut piece can be obtained simply by cutting the continuous sheet at predetermined intervals in the length direction. Usually, an interval for cutting in the length direction of the continuous sheet is set in accordance with the long side dimension of the target cut piece. The cutting interval in the length direction of the continuous sheet can also be set to the short side dimension of the cut piece. For example, when the continuous sheet is not cut in the width direction but is cut only in the length direction for each fixed dimension, the cut interval in the length direction can be set to 10 to 100 cm, preferably 10 to 50 cm.
As the cutting means in the length direction, a cutting means for cutting the continuous sheet by engaging the cutting blade and the cutting blade can be employed. Cutting by meshing is a technique of cutting a continuous sheet existing between the cutting edges when the cutting blade and the cutting blade move relative to each other.

Specifically, the following cutting means can be employed.
<Fixed blade and rotating blade>
A fixed blade that is fixedly arranged so as to cross in the width direction on one side of the continuous sheet, and a rotary blade that rotates along the running direction of the continuous sheet around the axis that crosses the width direction on the opposite side of the continuous sheet as a rotation center By meshing, cuts are made in the width direction of the continuous sheet and cut at regular intervals in the length direction.
The fixed blade can be disposed at a position where a thin strip-like blade is substantially in contact with one side of the continuous sheet so as to be orthogonal to the running direction of the continuous sheet.

  The rotary blade can be attached to the outer peripheral surface of a rotary drum that is rotationally driven by a motor or the like so that the blade tip protrudes in the diameter direction. The rotary blade can be provided at a plurality of locations in the circumferential direction of the rotary drum. The cutting interval of the continuous sheet can be controlled by adjusting the rotation speed of the rotary drum, that is, the rotary blade, and the traveling speed of the continuous sheet. Usually, the rotational speed of the rotary blade can be set in a range up to about 100 rpm. The rotational speed of the rotary blade can be changed between cutting the continuous sheet and passing the position away from the continuous sheet. For example, while cutting a continuous sheet, the rotating blade is moved in synchronization with the running of the continuous sheet, and after the cutting, the rotating blade is moved quickly to prevent adhesion of the continuous sheet and cut pieces, and the next cutting operation Can be prepared. A cutting device that synchronizes the moving speed of the cutting material and the moving speed of the cutting blade is called a synchronous type, and a low inertia servo motor or the like is used for the power of the rotary blade.

A flat strip-shaped rotary blade can be used as the rotary blade. The cutting edge of the rotary blade is arranged so as to pass through the position with a slight gap with respect to the cutting edge of the fixed blade. The clearance (clearance) between the blade edges can be set to 0.005 to 0.05 mm. Preferably it is 0.01-0.04 mm, More preferably, it is 0.01-0.03 mm. If the gap between the edges is too narrow, the cutting edges will hit each other due to temperature changes and the like, resulting in wear and damage. When the gap is too wide, it becomes difficult to cut a thin continuous sheet.
The cutting edge of the rotary blade and the cutting edge of the fixed blade may be arranged in parallel or may be arranged to be inclined with respect to each other. The cutting edge of the rotary blade can be inclined with respect to the linear cutting edge of the fixed blade. In this case, since the blade edge of the rotary blade is inclined along the cylindrical surface, the blade edge or the rotary blade is arranged in a spiral shape. In order to reduce the cutting resistance, it is generally preferable to set the inclination angle of the rotary blade relatively small for a thin continuous sheet and relatively large for a thick continuous sheet. The preferable inclination angle varies depending on the hardness and softness of the continuous sheet. Usually, it can be set to about 1 to 2 degrees.

When the continuous sheet is cut with the blade edge of the fixed blade and the blade edge of the rotary blade that are arranged to be inclined with respect to each other, the meshing position where the blade edges of the fixed blade and the rotary blade are closest to each other is changed from one end in the width direction of the continuous sheet to the other. By sequentially moving toward the end, a cut is formed that crosses the continuous sheet in the width direction. Thereby, the continuous sheet is cut smoothly and efficiently. Since the cutting position at each time point is substantially one point position, it is possible to prevent the surfaces of the fixed blade and the rotary blade from being pressed against and adhered to the continuous sheet for a long time.
As a material of the fixed blade and the rotary blade, a normal blade material can be adopted. For example, carbon steel, Swedish steel, bearing steel, ceramics, spring steel, powder high speed steel, die steel, alloy tool steel, cemented carbide, high speed steel, stainless steel, stainless steel, ferrotic and the like can be mentioned. When corrosion resistance is required, martensitic stainless steel (SUS440C, SUS420J2, etc.) is preferable.

<Rotating blade and rotating blade>
It is also possible to cut the continuous sheet by engaging the rotary blades with the rotary blades by disposing the rotary blades on both sides of the continuous sheet.
Also in this case, the rotary blades on both sides of the continuous sheet may be arranged in parallel to each other or may be arranged to be inclined with respect to each other. The inclination angles of the rotary blades on both sides may be different.
The material and structural conditions of the rotary blade can be set according to the combination of the fixed blade and the rotary blade described above.
<Prevention of adhesion>
The members such as cutting blades that make up the cutting device may be made of fluororesin material so that the continuous sheet is difficult to adhere, or anti-adhesion measures such as fluororesin coating may be taken only on the surface of the member. it can. As surface treatment for preventing adhesion, in addition to resin coating such as fluororesin, carburizing, nitriding, dicron treatment, atomloy treatment, nidax treatment, teflock, tungsten spraying, hard chrome plating, ceramic spraying, etc. can be employed.

It is also possible to form irregularities and grooves for preventing adhesion on the surface of the cutting blade.
As the structure of the cutting device, it is preferable for preventing adhesion that there is no structural member in the continuous sheet and the passage region of the cut piece as much as possible except members necessary for cutting, for example, a fixed blade and a rotating blade. For example, it is preferable not to provide a cover that surrounds the cutting location, but to open the periphery of the cutting location.
[Cutting in the width direction]
When the width of the continuous sheet is wider than the intended size of the cut piece, it is effective to cut the continuous sheet at regular intervals in the width direction.

The cutting interval in the width direction can be set to 10 to 100 cm.
The continuous sheet can be cut in the width direction either before or after cutting in the length direction. Usually, it is easier to work after cutting to a constant width in the width direction and then cutting at regular intervals in the length direction to obtain cut pieces.
Various sheet cutting means can be applied as means for cutting the continuous sheet in the width direction. A method in which the continuous sheet is difficult to adhere is preferable.
For example, with a rotary blade that rotates in a plane along the running direction of the continuous sheet, it is possible to cut the continuous sheet in the length direction and cut it at regular intervals in the width direction. Such a cutting method is called a slitter method. There are three known slitter cutting methods: razor cut, shear cut, and score cut. Either method can be adopted. In terms of cutting properties, shear cutting and score cutting are excellent. As a pass line through which the continuous sheet to be cut passes, a bent cut (lap slitting) leather cut, a bent cut shear cut, and a bent cut score cut that cuts the continuous sheet on the receiving roll or the lower blade are preferable.

In the score cut method, a disk-shaped rotating blade is pressed above a continuous sheet that runs along the upper surface of the receiving roll, and the continuous sheet sandwiched between the rotating blade and the receiving roll is cut off. . Pressure can be applied to a structural member such as a support shaft of the disk-shaped rotary blade by air pressure or the like. The air pressure can be set to 0.3 to 1.0 MPa. Preferably it can be set to 0.4-0.8 MPa, More preferably, it can be set to 0.4-0.6 MPa. It is preferable that the surface material of the receiving roll is higher in hardness than the material of the rotary blade in terms of increasing durability.
In the shear cut method, a continuous sheet is fed into a place where a side surface of a disk-shaped rotary blade passes through a side surface of another rotating blade portion and cut by a shearing action. The clearance between the pair of blades performing the shearing action can be set to 5 to 15% of the thickness of the cutting material. When the cutting blade is a one-sided blade, it can be used by lightly contacting the other blade portion. Contact pressure can also be applied with a coil spring or air pressure.

Further, a cutting method in which the various cutting methods described above are combined or partially changed is also employed.
As for the cutting means in the width direction, as with the cutting means in the length direction described above, the fluororesin coating or the like adheres to the surface of the cutting blade or the member on which the continuous sheet may adhere in the vicinity thereof. Preventive measures can be taken.
[Adhesion prevention medium]
Supply an anti-adhesion medium to the location where the continuous sheet may come into contact near the cutting location, such as a fixed blade or rotary blade that cuts the continuous sheet, or a fixed blade and rotating blade mounting member. It is effective to prevent adhesion. The adhesion preventing medium is effective not only for preventing adhesion between a member such as a cutting blade and the continuous sheet, but also for preventing the cut surfaces of the cut continuous sheet from reattaching.

As the adhesion preventing medium, a liquid or gas that does not deteriorate the performance of the continuous sheet, deteriorate the performance, or adversely affect the subsequent crushing process can be used. Specific examples include water, warm water, and water vapor. Hot water of about 60 to 90 ° C. can be used as hot water.
The adhesion preventing medium can be supplied to a predetermined portion of the cutting device using spraying means such as a spray device or a shower nozzle. In the case of a rotary blade, it is effective to supply the anti-adhesion medium at a location where the rotary blade rotates and passes, not at the cutting location.
The supply amount of the adhesion preventing medium varies depending on conditions such as the cutting method and the structure of the cutting blade.
For example, when water is used as the adhesion preventing medium, the amount of water supplied can be set to about 5 to 2000 g / min with respect to the traveling speed of the continuous sheet of 2 to 15 m / min. In the case of hot water, the same supply amount range can be adopted. In the case of water vapor, about 25 to 10000 g / min can be set in consideration of the amount dissipated by scattering or the like.

[Thermal strain prevention]
A cutting means including a cutting blade such as a rotary blade or a fixed blade that cuts a continuous sheet may be distorted by heat generated by the cutting action. When such thermal distortion occurs, the position, dimensions, and shape of the cutting blades change slightly, and the gap between the cutting blades also changes, resulting in poor sharpness and wear and damage to the cutting blades. It becomes easy.
Therefore, a means for preventing or suppressing the occurrence of thermal distortion can be provided in the cutting means. As such a thermal strain preventing means, a mechanism or device similar to a thermal strain preventing structure or a thermal strain preventing device provided in a normal cutting device can be adopted.

The supply of the anti-adhesion medium described above can also be used as a thermal strain prevention means. By spraying or contacting the adhesion preventing medium to the cutting blade, it is possible to take out the heat of the cutting blade and prevent the occurrence of thermal distortion.
The medium used for preventing thermal distortion is preferably a medium having high thermal conductivity or a large heat capacity. What has the characteristic which does not drop the sharpness of a cutting blade is preferable.
Water, warm water or water vapor is useful for preventing adhesion as well as preventing thermal distortion, and is excellent in terms of easy handling. The supply amount of water, warm water or water vapor can be set within the range described for the prevention of adhesion. However, it is effective to set a relatively large amount in the supply amount range in order to sufficiently perform the function of preventing thermal distortion without aiming only at adhesion prevention.

[Continuous sheet cutting posture]
Depending on the posture or running direction of the continuous sheet when cutting the continuous sheet, it is possible to effectively prevent the continuous sheet from adhering to the cutting device and the cut pieces from adhering to each other.
When the continuous sheet is cut at regular intervals in the length direction, the continuous sheet can be run in the vertical direction so as to hang down from above. The fixed blade and the rotary blade or the rotary blade and the rotary blade of the cutting device are arranged to face both sides of the continuous sheet that runs vertically. When the continuous sheet is cut, the cut piece separated from the continuous sheet falls due to its own weight, so that it is immediately separated without adhering to a component of the cutting device such as a cutting blade. It is possible to prevent the cut surfaces from reattaching. Even if a continuous roller does not use a conveyance roller or a conveyor, the continuous sheet is moved by its own weight, so that the continuous sheet does not adhere to the conveyance roller or the conveyor. If the cut piece falling under its own weight is received at the inlet of the continuous crushing device installed below the dropping path, it can be reliably and efficiently supplied to the continuous crushing device.

Instead of running the continuous sheet vertically downward, it can be cut in the length direction while running in a direction inclined obliquely downward. Also in this case, the vertical component of gravity applied to the continuous sheet or the cut piece smoothes the separation of the cut piece from the continuous sheet. Further, even if a conveyor conveyer disposed at an inclination is used to run the continuous sheet at an angle, the continuous sheet is prevented from being strongly pressed against the surface of the conveyor, so that it is difficult to adhere.
[Disintegration of cut pieces]
The cut pieces cut from the continuous sheet are continuously supplied to the continuous crushing device, and the supply amount of the cut pieces and the crushing and discharging capacity of the continuous crushing device are such that the supply amount ≦ the crushing discharge capacity. Then, crushing and discharging are continuously performed to obtain hydrogel particles.

As the continuous crushing apparatus, among various crushing apparatuses utilized in a normal water absorbent resin manufacturing technique, an apparatus suitable for continuous work can be used.
For example, a screw extrusion type crusher can be used. The basic structure of the screw extrusion type crusher is that the screw rotates in a cylindrical barrel, and the cut pieces supplied to the barrel material inlet are crushed while being agitated as the screw rotates. Then, it is transferred forward and extruded from the extruded porous plate disposed at the tip of the barrel, so that hydrogel particles having a particle size corresponding to the pore diameter of the extruded porous plate are obtained. The larger the pore size, the larger the hydrogel particle size. However, the pore diameter of the extruded perforated plate does not match the particle diameter of the obtained hydrogel particles, and there is a tendency that hydrogel particles having a particle diameter smaller than the pore diameter are obtained. A rotary blade for cutting the processing material can be provided inside the extruded perforated plate. The detailed structure can be employed by appropriately combining structures similar to known screw extrusion type crushing apparatuses. As a specific example of the screw extrusion type crushing apparatus, a commercially available apparatus such as a meat chopper (manufactured by Hiraga Kakusha Co., Ltd.) or a dome gran (manufactured by Fuji Powder Co., Ltd.) can be used. In addition to a single screw extruder having a single screw, a twin screw extruder or a twin screw extruder can also be employed. When the screw is a double shaft, there are a screw having the same direction of rotation and a screw having a different rotation direction.

The screw extrusion type crushing device can change the crushing amount per unit time or the discharge amount of the hydrogel particles by adjusting the rotational speed of the screw.
Continuous crushers include vertical crushers such as Rotoplex (manufactured by Hosokawa Micron), screw type crushers such as triaxial special screw type alpha (manufactured by Nippon Spindle Manufacturing Co., Ltd.), Gainax (registered trademark) crusher (manufactured by Horai Co., Ltd.) ) Etc. can also be used.
In a continuous crushing device, when a larger amount of cut pieces than the crushing and discharging capacity are supplied, the cut pieces are retained or clogged inside the device. If the cut pieces are excessively stirred or kneaded in the apparatus, the characteristics of the hydrogel are changed or deteriorated.

Therefore, the crushing and discharging are continuously performed under the condition that the supply amount of the cut pieces and the crushing and discharging ability of the continuous crushing apparatus satisfy the condition that the supply amount ≦ the crushing and discharging ability.
The barrel of the continuous crusher can be provided with a temperature adjustment mechanism that cools or heats the processing material.
[Hydrated gel particles]
The hydrogel particles discharged from the continuous crusher are in a particle state such as a spherical shape. The shape of the hydrogel particles varies depending on the crushing conditions. In addition to spherical shapes, there are ellipsoids, long cylinders, and irregular shapes. Even when the polymerization at the time of production is accompanied by foaming, most of the particles are amorphous so as not to contain bubbles because the bubble size is relatively large.

The particle size of the hydrogel particles can be set in the range of 0.5 to 3 mm.
The hydrogel particles can be used for various applications as they are. It can be used for hygiene products, agriculture and horticulture. For the fluidity of the particles, a particulate inorganic substance (bentonite, zeolite, silicon oxide, etc.) may be mixed.
The hydrogel particles can be dried and used as dry water-absorbent resin particles. As a drying method, a drying method that makes good contact with hot air or a heat transfer surface while moving the material, such as a stirring drying method, a fluidized bed drying method, and an airflow drying method, is preferably used.
The hydrogel particles can be treated with various treatment liquids or dried after the treatment. Surface treatment such as surface crosslinking can also be applied.

In the method for producing hydrogel particles according to the present invention, a continuous sheet of a high-concentration hydrogel crosslinked polymer is run in the length direction while being cut at regular intervals in the length direction to obtain cut pieces. The supplied cut pieces are continuously supplied to the continuous crushing device, and the supply amount of the cut pieces and the crushing and discharging capacity of the continuous crushing device are continuously supplied under the condition that the supply amount ≦ the crushing discharge capacity. By pulverizing and discharging to obtain water-containing gel particles, it is possible to efficiently produce water-containing gel particles with high quality performance from which water-absorbing resin particles having excellent water absorption performance can be obtained.
When a continuous sheet of hydrogel is supplied to a continuous crushing device as a continuous sheet, without cutting into pieces, the supply amount of the continuous sheet and the crushing discharge capacity of the continuous crushing device must be matched exactly. I must. When the supply amount of the continuous sheet is too large, the continuous crushing apparatus is clogged with an excessive continuous sheet. If the supply amount of the continuous sheet is too small, a large tension is applied to the continuous sheet from the continuous crushing device, the continuous sheet is cut, and continuous supply cannot be performed.

Since the supply amount of the continuous sheet, that is, the production amount is determined by the production conditions such as the polymerization process, the crushing discharge capacity of the continuous crushing device must be matched with the supply amount of the continuous sheet. Selection or design is difficult, and the equipment cost increases. If the production conditions of the continuous sheet are changed, the continuous crushing apparatus may have to be changed.
Therefore, in the present invention, it is effective to perform crushing and discharging continuously under the condition that the supply amount of the cutting piece ≦ the crushing discharge capacity after obtaining the cut piece from the continuous sheet.
As a method of cutting the continuous sheet in the length direction, while moving the continuous sheet in the length direction, a fixed blade and a rotary blade (the fixed blade is fixedly arranged to cross the width direction on one side of the continuous sheet, The rotating blade cuts the continuous sheet in the length direction by meshing the continuous sheet (rotating along the running direction of the continuous sheet with the axis crossing the width direction on the opposite side of the continuous sheet as the center of rotation). A strong high-concentration water-containing gel sheet can be efficiently cut without adhering to a cutting blade or other device member or clogging the device.

〔overall structure〕
The embodiment shown in FIGS. 1 and 2 produces hydrous gel particles from a high concentration hydrous gel sheet.
The hydrogel sheet 10 is a continuous sheet manufactured in a band shape by a continuous stationary polymerization method on an endless belt, and is continuously run in the length direction by a conveying means such as a conveyor. Although it is displayed in the form of a flat sheet in the figure, in reality, there are undulations and undulations in the thickness direction, fluctuations in thickness, and fluctuations in width.
The continuous sheet 10 of hydrogel running in the horizontal direction is supplied to the slitter device 20. The running speed of the continuous sheet 10 supplied to the slitter device is 4.5 m / min, and the width of the continuous sheet 10 is about 80 cm.

<Slitter device>
The slitter device 20 includes a receiving roll 22 disposed on the back surface side of the continuous sheet 10 and a disk-shaped rotary blade 24 disposed on the front surface side of the continuous sheet 10. As shown in FIG. 2, a plurality of disk-shaped rotary blades 24 are arranged at intervals in the width direction of the continuous sheet 10. The disk-shaped rotary blade 24 cuts into the continuous sheet 10, and the continuous sheet 10 is cut in the length direction and cut in the width direction. The position and number of cuts formed in the continuous sheet 10 can be changed depending on the number and arrangement intervals of the disk-shaped rotary blades 24.
FIG. 5 shows a detailed structural example of the slitter device 20. The structure of FIG. 5 (a) is obtained by coating a corrosion-resistant stainless steel with a fluororesin, and the surface of the receiving roll 22 having a cylindrical shape with a diameter of 14 cm is also made of a fluororesin-coated corrosion-resistant stainless steel with a cutting edge diameter of 7.5 cm. This is a score cut method in which the continuous sheet 10 is cut in a state where the tips of the disc-shaped rotary blades 24 are arranged so as to be substantially in contact with each other. Cutting is performed by applying pressure with air pressure or the like so that the disk-shaped rotary blade 24 is pressed from the upper surface side of the continuous sheet 10.

The structure shown in FIG. 5B is made of a fluororesin-coated corrosion-resistant stainless steel as described above, and is provided with a concave groove 23 in a receiving roll 22 having a diameter of 14 cm, and the opening peripheral edge of the concave groove 23 is a blade portion. It is made of a fluororesin coated corrosion resistant stainless steel and is arranged so that the side surface of the rotary blade 24, which is a disc-shaped single oversized blade having a cutting edge diameter of 7.5 cm, is substantially in contact with the inner side surface of the groove 23. The continuous sheet 10 is a shear-cut method in which the continuous sheet 10 is sandwiched between the side surface of the disk-shaped rotary blade 24 and the opening periphery of the groove 23 and is cut by a shearing action.
As shown in FIG. 1, a water spray nozzle 26 that is an anti-adhesion liquid is disposed near the disc-shaped rotary blade 24. By spraying water from the spray nozzle 26 to the disk-shaped rotary blade 24, the material of the continuous sheet 10 is prevented from adhering to the disk-shaped rotary blade 24, and the sharpness of the disk-shaped rotary blade 24 is maintained.

The continuous sheet 10 that has passed through the slitter device 20 and has been scored in the width direction is changed along the receiving roll 22 from the horizontal direction to the vertically downward direction.
<Cutting device>
The continuous sheet 10 that drops and travels vertically downward is supplied to the cutting device 30.
As shown in detail in FIG. 3A, the cutting device 30 includes a linear fixed blade 32 that is horizontally supported so as to cross the width direction of the continuous sheet 10 on one side of the continuous sheet 10. Further, at a position facing the fixed blade 32, a rotating drum 34 that traverses in the width direction of the continuous sheet 10 on the opposite surface side of the continuous sheet 10, and rotates around the running direction of the continuous sheet 10, and an outer periphery of the rotating drum 34. It has a plate-like rotary blade 36 that protrudes in a diametrical direction from the surface and is arranged spirally along the outer peripheral surface of the rotary drum 34 so as to be slightly inclined with respect to the axial direction of the rotary drum 34. Since the plate-like rotary blade 36 is attached to the outer peripheral surface of the rotary drum 34 in this way, a shaft (not shown) that crosses the continuous sheet 10 in the width direction is rotated on the opposite surface side of the continuous sheet 10. It can rotate along the running direction of the continuous sheet 10 as a center.

The fixed blade 32 is made of fluororesin-coated corrosion-resistant stainless steel, and the width in the blade edge direction is 7 cm. The rotating drum 34 is made of a fluororesin coated corrosion resistant stainless steel and has an outer diameter of 20 cm. The plate-like rotary blade 36 is made of fluororesin-coated corrosion-resistant stainless steel, and the protruding length from the outer peripheral surface of the rotary drum 34 is 7 cm.
As the rotary drum 34 rotates, the tip of the fixed blade 32 and the tip of the plate-like rotary blade 36 pass so as to mesh with each other. Since the plate-like rotary blade 36 is inclined spirally, the meshing position C between the plate-like rotary blade 36 and the fixed blade 32 sequentially moves from one end side in the axial direction to the other end side. As the mesh position C moves, the continuous sheet 10 is cut at the mesh position C. The continuous sheet 10 contacts only with the fixed blade 32 and the plate-like rotary blade 36 around the meshing position C, and the continuous sheet 10 does not contact and adhere to the outer peripheral surface of the rotating drum 34 or the like.

As shown in FIG. 3B, a slight gap, that is, a clearance x is provided between the tip of the fixed blade 32 and the tip of the plate-like rotary blade 36. By adjusting this clearance x appropriately, the sharpness can be improved, and the durability of the fixed blade 32 and the plate-like rotary blade 36 can be improved.
The cutting interval in the length direction of the continuous sheet 10 can be changed by the relationship between the installation interval or number of the plate-like rotary blades 36 to the rotary drum 34, the rotational speed of the rotary drum 34, and the traveling speed of the continuous sheet 10.
As shown in FIG. 1, a nozzle 38 for spraying an anti-adhesion liquid similar to that described above is installed obliquely above the fixed blade 32 and obliquely above the rotating drum 34, and the fixed blade 32 and the plate-shaped rotating blade 36. The continuous sheet 10 is prevented from adhering to the surface. The spray nozzle 38 installed obliquely above the rotary drum 34 sprays water on the plate-like rotary blade 36 from the outside of the region where the plate-like rotary blade 36 rotates.

As shown in FIG. 2, the continuous sheet 10 divided in the width direction by the slitter device 20 is cut by the cutting device 30 in the length direction at regular intervals. As a result, a cut piece 12 having a substantially rectangular shape is obtained. In FIG. 2, the cut piece 12 is displayed in a completely rectangular shape, but the cut piece 12 cut by the inclined plate-like rotary blade 36 of the cutting device 30 is a parallelogram or rhombus in which the rectangle is slightly distorted. There is a possibility of close shape.
As shown in FIG. 1, if the continuous sheet 10 that moves vertically downward is cut in the length direction by the cutting device 30, the cut piece 12 that has been cut falls due to its own weight.
<Continuous crusher>
As shown in FIG. 1, a screw extrusion type continuous crushing device 40 is installed below the cutting device 30.

The continuous crushing device 40 has a workpiece inlet 42 at the top. The insertion port 42 has a shape and a size with which the cut piece 12 supplied from the cutting device 30 is reliably dropped. For example, it has a rectangular opening of 50 cm × 50 cm.
A cylindrical barrel portion 44 and a screw portion 46 that rotates inside the barrel portion 44 are provided below the insertion port 42. The screw portion 46 is rotationally driven by a motor or the like. At the tip of the barrel portion 44, there is an extruded perforated plate 48 through which many fine holes pass.
The cut piece 12 supplied to the insertion port 42 moves to the front side while being stirred and crushed in the barrel portion 44 as the screw portion 46 rotates. Finally, it is extruded from the extruded perforated plate 48, becomes the hydrogel particles 14, and is discharged from the continuous crushing device 40. The particle size of the hydrogel particles 14 is considerably smaller than the pore size of the extruded porous plate 48. For example, the particle size of the hydrogel particles 14 obtained by extrusion from the extruded perforated plate 48 having a pore diameter of 16 mm may be about 2.5 mm.

[Changing cutting device]
FIG. 4 shows a structure of the cutting device 30 different from the above embodiment.
A rotary drum 34 and a plate-like rotary blade 36 are arranged on both front and back surfaces of the continuous sheet 10 that moves vertically downward. An anti-adhesion spray nozzle 38 is also provided on both.
Since the left and right rotating drums 34 rotate along the traveling direction of the continuous sheet 10, they rotate in opposite directions.
The plate-like rotary blades 36 attached to the left and right rotary drums 34 so as to be inclined with respect to the axial direction pass at the position of the central continuous sheet 10 so that the left and right plate-like rotary blades 36 are engaged with each other. The meshing position C of the left and right plate-like rotary blades 36 moves from one end side of the continuous sheet 10 to the other end side, thereby cutting the continuous sheet 10.

In this embodiment, since both of the blades that cut the continuous sheet 10 are the plate-like rotary blades 36, the relative movement speed of each other increases, and the continuous sheet 10 can be cut quickly and strongly.
Also in this embodiment, a clearance x is provided between the tips of a pair of plate-like rotary blades 36 and 36 that mesh with each other, as in the embodiment shown in FIG. In particular, since the plate-like rotary blades 36 and 36 both rotate and move, it is important to appropriately adjust the clearance x.
[Another embodiment]
In the embodiment shown in FIG. 6, the arrangement structure of the slitter device 20 and the cutting device 30 is different from the above embodiment.

The continuous sheet 10 that has passed through the slitter device 20 and has a cut in the length direction is caused to run diagonally downward instead of vertically downward. A transport conveyor 50 is installed on the downstream side of the slitter device 20, and the transport surface of the transport conveyor 50 faces obliquely downward. The conveyance surface of the conveyance conveyor 50 is subjected to fluororesin processing or the like to reduce adhesion to the continuous sheet 10.
A cutting device 30 is installed obliquely downward on the downstream side of the conveyor 50. The continuous sheet 10 is cut in the length direction by the cutting device 30, and the obtained cut piece 12 falls freely. By the action of inertia and gravity by the traveling so far, it is initially moved obliquely downward to move away from the fixed blade 32 and the plate-like rotary blade 36 of the cutting device 30, and thereafter falls downward vertically by the action of gravity. Become. Therefore, it is desirable that the input port 42 of the continuous crushing device 40 is arranged in accordance with the dropping path of the cut piece 12.

The results of evaluating specific implementation techniques and their performance are shown.
[Performance measurement method]
<Absorption magnification GV>
Measure the absorption capacity under no load. 0.2 g of a sample was uniformly placed in a non-woven bag (60 mm × 60 mm) and immersed in a 0.9 wt% sodium chloride aqueous solution (physiological saline). After 30 minutes, the bag was pulled up, drained at 250 × 9.81 m / s ² (250 G) for 3 minutes using a centrifuge, and the weight W1 (g) of the bag was measured. Further, the same operation was performed without using the water absorbent resin, and the weight W0 (g) at that time was measured. Then, from these weights W1 and W0, the absorption capacity GV under no load was measured by the following formula.

GV (g / g) = [(W1-W0) / weight of sample (g)]-1
<Water-soluble component amount>
Weigh out 184.3 g of 0.9 wt% NaCl aqueous solution (saline) in a 250 ml lidded plastic container, add 1.00 g of the sample to the aqueous solution and stir for 16 hours to dissolve the soluble component in the resin. Was extracted and its amount was measured.
<Saline flow inductive SFC>
It carried out according to the physiological saline flow inductivity (SFC) test of Tokuheihei 9-509591.
[Example 1]
<Manufacture of hydrous gel sheet>
The following solutions were stirred and mixed at a predetermined flow rate to prepare a monomer solution.

43.5 wt% sodium hydroxide aqueous solution 73.5 g / s,
59.2 wt% acrylic acid aqueous solution 169.2 g / s,
77.4 parts by weight of a 50% by weight aqueous acrylic acid solution, 0.781 parts by weight of 2-hydroxymethyl-2-methylpropiophenone, 0.849 parts by weight of a 46% by weight aqueous solution of 5 sodium diethylenetriaminepentaacetic acid, polyethylene glycol diacrylate (average Molecular weight 523) 1.43 g / s of a solution in which 21.0 parts by weight are dissolved,
The temperature of this monomer solution was stable at about 95 ° C.
The monomer liquid was continuously supplied to the supply pipe and stirred continuously in the supply pipe, and then a 3 wt% aqueous sodium persulfate solution was combined at a flow rate of 3.40 g / s to obtain a mixed liquid. The mixed solution had a monomer concentration of 45% by weight and a neutralization rate of 70 mol%.

The belt polymerization device has an endless belt with an effective length of 7.0m and a width of 1.5m, and the surface is coated with fluororesin. A UV lamp is installed on the belt, and the bottom and surroundings are heated and kept at about 100 ° C. Then, an apparatus in which an intake pipe for collecting evaporated water was installed at the center was used.
The mixed solution was supplied to a belt polymerization apparatus so as to have a monomer thickness of 5.6 mm, and polymerization was continuously performed at a belt speed of 4.5 m / min. 60% by weight of solid content, sheet width after shrinkage of about 80 cm, sheet thickness of 2 mm to 20 mm (there is a wrinkle that occurs when shrinking after expansion, and the wrinkle may be folded, resulting in a width in the thickness), and the surface temperature is about 70 ° C. A belt-like hydrogel polymer sheet was obtained.

<Manufacture of cut pieces>
The obtained continuous sheet composed of the band-like hydrogel polymer was immediately supplied to the slitter device by the conveyor belt. The slitter device has a basic structure shown in FIG. Score cutter type rotary blades having a diameter of 75 mm and a thickness of 2 mm are arranged at three positions at intervals, and a receiving roll having a diameter of 140 mm is provided facing the rotary blade. The continuous sheet was divided into four parts with a width of 20 cm in the width direction at an air pressure of 0.40 MPa applied to the score cutter blade.
The continuous sheet divided in the width direction by the slitter device changed the traveling direction along the receiving roll, and was supplied to the cutting device while being hung by its own weight in the vertical direction.

The cutting device has the basic structure shown in FIG. A fixed blade with a thickness of 20 mm and a length of 70 mm up to the blade edge, a roll-shaped rotary drum with a diameter of 200 mm, and a spiral plate with a thickness of 14 mm, a length of 70 mm up to the blade edge and a width of 1.4 m And a rotary blade. Only one plate-like rotary blade is provided on the rotary drum. The clearance between the fixed blade and the rotary blade is adjusted to about 0.01 mm. This cutting device is a semi-synchronous rotary cutter.
The continuous sheet was continuously cut every 15 cm in the length direction at a rotational speed of 30 rpm of the rotary drum. A cut piece having a substantially rectangular shape of 20 cm × 15 cm was obtained. Adherence of the continuous sheet to the score cutter blade and the receiving roll of the slitter device and the fixed blade, rotary blade and rotary cylinder of the cutting device was not recognized. No reattachment of the cut surfaces of the cut pieces was observed. However, when the operation was performed for a long time, the continuous sheet adhered to the cutting blade and the reattachment between the cut surfaces of the cut pieces were recognized, but there was no problem in practical use.

<Continuous cracking>
The cut piece produced with the cutting device was crushed with a meat chopper having a hole diameter of 16 mm of extrusion holes to obtain hydrous gel particles.
As the meat chopper, a meat chopper type 72 (manufactured by Hiraga Corporation: processing capacity of about 6 t / hr at a screw rotation speed of 105 rpm) was used. This apparatus is a screw extrusion type continuous crushing apparatus. The inlet of the meat chopper is about 50 cm × 50 cm, and can reliably receive the cut piece produced in the previous step.
By setting the screw speed to 15 rpm, the treatment capacity of the hydrogel particles that can be crushed and discharged by the meat chopper was 0.86 t / hr. The supply amount of the cut pieces supplied from the cutting device to the meat chopper device was 0.66 t / hr. Satisfies the condition of supply amount to meat chopper device ≦ crushing discharge capacity.

The biting state in the meat chopper was good, no stagnation occurred, the discharge state was good, and continuous discharge was performed. No residence in the hopper of the charging part was observed.
<Production of water-absorbent resin particles>
The hydrogel particles discharged from the meat chopper were dried with hot air at 180 ° C. for 40 minutes to obtain a dried product, and then pulverized with a roll mill to obtain particulate water-absorbing resin particles (1). Using a sieve, the water-absorbent resin particles (1) having a particle size in the range of 300 μm to 600 μm were classified and their physical properties were measured. The absorption capacity was 42 (g / g), and the amount of water-soluble components was 14% by weight. Subsequently, heat treatment was performed at 212 ° C. using a mortar mixer in a butanediol / propylene glycol / water / 24% caustic soda system. The physical properties of the water-absorbent resin particles after the treatment were as follows: the absorption capacity was 30 (g / g), and the saline flow conductivity (SFC) was 40. It was confirmed that the water-absorbent resin particles have practically sufficient performance.

[Example 2]
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was supplied to a slitter device by a conveyor belt.
The slitter device is the same score cutter as in Example 1, but the score cutter blade and the receiving roll are coated with fluororesin. In the same manner as in Example 1, the continuous sheet was divided into four parts with a width of 20 cm in the width direction.
A continuous sheet hung vertically downward from the slitter device was supplied to the cutting device.

The cutting device basically has the same structure as that of the first embodiment, but the fixed blade and the rotary blade are coated with fluororesin. The continuous sheet was continuously cut every 15 cm in the length direction at a rotation speed of the rotating drum of 30 rpm. A 20 cm × 15 cm approximately rectangular cut piece was obtained. Adhesion of a continuous sheet with a slitter device and a cutting device was not recognized. No reattachment of the cut surfaces of the cut pieces was observed. Even after a long period of operation, both the adhesion and re-adhesion were very slight.
<Continuous cracking>
The cut pieces were crushed under the same processing conditions using the same meat chopper as in Example 1 to obtain hydrogel particles.

<Production of water-absorbent resin particles>
The hydrogel particles were treated in the same process as in Example 1 to obtain particulate water-absorbing resin particles (2). In the same manner as in Example 1, particles having a particle diameter of 300 μm to 600 μm of the water-absorbent resin particles (2) were classified and their physical properties were measured. The absorption capacity was 42 (g / g), and the amount of water-soluble components was 14% by weight. Subsequently, as for the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1, the absorption ratio was 30 (g / g), and the SFC was 40. As in Example 1, water-absorbing resin particles having good physical properties were obtained.
Example 3
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was supplied to a slitter device by a conveyor belt.

The slitter device is the same score cutter as in Example 1, but a rotary blade and a receiving roll coated with fluororesin were used. A spray nozzle that sprays water on the rotary blade was used. The amount of water sprayed was 5 to 10 cc / min.
In the same manner as in Example 1, the continuous sheet was divided into four parts with a width of 20 cm in the width direction.
A continuous sheet hung vertically downward from the slitter device was supplied to the cutting device.
The cutting device basically has the same structure as that of the first embodiment, but the fixed blade and the rotary blade are coated with fluororesin. A spray nozzle for spraying water and a device for supplying water to the spray nozzle were installed on each of the fixed blade and the rotary blade. The amount of water sprayed was 5 to 10 cc / min. The continuous sheet was continuously cut every 15 cm in the length direction at a rotation speed of the rotating drum of 30 rpm. A 20 cm × 15 cm approximately rectangular cut piece was obtained.

Adhesion of a continuous sheet with a slitter device and a cutting device was not recognized. No reattachment of the cut surfaces of the cut pieces was observed. Even after operation for a long time, the adhesion and re-adhesion were not observed at all.
<Continuous cracking>
The cut pieces were crushed under the same processing conditions using the same meat chopper as in Example 1 to obtain hydrogel particles.
<Production of water-absorbent resin particles>
The hydrogel particles were processed in the same process as in Example 1 to obtain particulate water-absorbing resin particles (3). In the same manner as in Example 1, the water-absorbent resin particles (3) having a particle size in the range of 300 μm to 600 μm were classified and their physical properties were measured. The absorption capacity was 42 (g / g), and the amount of water-soluble components was 14% by weight. Subsequently, as for the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1, the absorption ratio was 30 (g / g), and the SFC was 40. As in Example 1, water-absorbing resin particles having good physical properties were obtained.

Example 4
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was supplied to a slitter device by a conveyor belt.
The slitter apparatus used the same score cutter as Example 1, and divided the continuous sheet into four parts with a width of 20 cm in the width direction.
A continuous sheet hung vertically downward from the slitter device was supplied to the cutting device.
The cutting device has the basic structure shown in FIG. A rotary drum having a diameter of 200 mm, a spiral rotary blade having a thickness of 14 mm, a length to the blade edge of 70 mm, and a width of 1.4 m are arranged at intervals on the left and right. Each rotary drum is provided with one rotary blade. The clearance between the rotary blades is adjusted to about 0.01 mm. This cutting device is a full-synchronous rotary cutter. The rotation number of the rotating drum was set to 30 rpm, and the continuous sheet was continuously cut every 15 cm in the length direction. A 20 cm × 15 cm approximately rectangular cut piece was obtained. The adhesion of the gel sheet to the rotary blade, the rotary drum, etc. was not recognized, and the reattachment of the cut surfaces was not recognized.
During the operation for a long time, the adhesion or re-adhesion occurred a little, but there was no problem in practical use.

<Continuous cracking>
The cut pieces were crushed under the same processing conditions using the same meat chopper as in Example 1 to obtain hydrogel particles.
<Production of water-absorbent resin particles>
The hydrogel particles were treated in the same process as in Example 1 to obtain particulate water-absorbing resin particles (4). In the same manner as in Example 1, the water-absorbent resin particles (4) having a particle diameter in the range of 300 μm to 600 μm were classified and their physical properties were measured. The absorption capacity was 42 (g / g), and the amount of water-soluble components was 14% by weight. Subsequently, as for the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1, the absorption ratio was 30 (g / g), and the SFC was 40. As in Example 1, water-absorbing resin particles having good physical properties were obtained.

Example 5
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was supplied to a slitter device by a conveyor belt.
The slitter apparatus used the apparatus which has the same fluororesin-coated score cutter as Example 2, and divided the continuous sheet into 4 parts by 20 cm width in the width direction.
A continuous sheet hung vertically downward from the slitter device was supplied to the cutting device.
The cutting device is a full-synchronous rotary cutter coated with a fluororesin having the same structure as that of the fourth embodiment. The continuous sheet was continuously cut every 15 cm in the length direction at a rotational speed of 30 rpm of the rotary drum. A 20 cm × 15 cm approximately rectangular cut piece was obtained. The adhesion of the gel sheet to the rotary blade, the rotary drum, etc. was not recognized, and the reattachment of the cut surfaces was not recognized.
The adhesion and reattachment after a long operation were very slight.

<Continuous cracking>
The cut pieces were crushed under the same processing conditions using the same meat chopper as in Example 1 to obtain hydrogel particles.
<Production of water-absorbent resin particles>
The hydrogel particles were treated in the same process as in Example 1 to obtain particulate water-absorbing resin particles (5). In the same manner as in Example 1, the particles of the water absorbent resin particles (5) having a particle size in the range of 300 μm to 600 μm were classified and their physical properties were measured. The absorption capacity was 42 (g / g), and the amount of water-soluble components was 14% by weight. Subsequently, the physical properties of the heat-treated product subjected to the same heat treatment as in Example 1 had an absorption ratio of 30 (g / g) and an SFC of 40. As in Example 1, water-absorbing resin particles having good physical properties were obtained.

Example 6
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was supplied to a slitter device by a conveyor belt.
The slitter device has a basic structure shown in FIG. A shear cutter upper blade which is a disc-shaped rotary blade coated with fluororesin with a diameter of 75 mm, a shear cutter lower blade with a knife shaft with a diameter of 150 mm coated with fluororesin (a receiving roll with a concave groove), and water is distributed to the shear cutter. Device (distribution amount: 5 to 10 cc / min). The upper and lower blades were lightly contacted, and the continuous sheet was divided into four parts with a width of 20 cm while maintaining the contact pressure constant.

A continuous sheet hung vertically downward from the slitter device was supplied to the cutting device.
The cutting device is a full-synchronous rotary cutter coated with a fluororesin having the same structure as that of the fourth embodiment. A water spray nozzle and water supply device are also installed. The amount of water sprayed was 5 to 10 cc / min.
The continuous sheet was continuously cut every 15 cm in the length direction at a rotational speed of 30 rpm of the rotary drum. A 20 cm × 15 cm approximately rectangular cut piece was obtained. The adhesion of the gel sheet to the rotary blade, the rotary drum, etc. was not recognized, and the reattachment of the cut surfaces was not recognized. The same was true after long hours of operation.

<Continuous cracking>
The cut pieces were crushed under the same processing conditions using the same meat chopper as in Example 1 to obtain hydrogel particles.
<Production of water-absorbent resin particles>
The hydrogel particles were treated in the same process as in Example 1 to obtain particulate water-absorbing resin particles (6). In the same manner as in Example 1, the water-absorbent resin particles (6) having a particle diameter in the range of 300 μm to 600 μm were classified and their physical properties were measured. The absorption capacity was 42 (g / g), and the amount of water-soluble components was 14% by weight. Subsequently, as for the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1, the absorption ratio was 30 (g / g), and the SFC was 40. As in Example 1, water-absorbing resin particles having good physical properties were obtained.

[Comparative Example 1]
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was supplied to a slitter device by a conveyor belt.
The slitter apparatus used the same fluororesin-coated score cutter as in Example 2, and the continuous sheet was divided into four with a width of 20 cm in the width direction in the same manner as in Example 1.
One of the four continuous sheets (width of about 20 cm) was cut with an SGE-220 type sheet pelletizer (manufactured by Horai Co., Ltd.) having an effective cutting width of 22 cm. This sheet pelletizer is based on slit cutting with a vertical cutting blade made of a roll cutter, and a linear plate-like rotary blade that is arranged adjacent to the lower portion of the vertical cutting blade and extends in the axial direction attached to the rotary drum. This is a device for cutting sheet material by transverse cutting. The rotational speed of the transverse cutting blade was 250 rpm, and the clearance (clearance) between the rotating blade and the fixed blade was set to about 0.05 to 0.08 mm. In order to prevent adhesion, water was sprayed at a spray rate of 40 to 50 cc / min on both the vertical and horizontal sections.

However, a part of the continuous sheet adheres to the rotary blade for transverse cutting, the cut surfaces of the cut pieces reattach, or the hood part that surrounds the outer periphery of the rotary blade is cut between the rotary blade. There was a problem of clogging. Even after removing the deposits and restarting, clogging occurred immediately, and the continuous sheet could not be cut continuously.
<Manufacture of crushing and water-absorbing resin particles>
A dango-like lump (size of about 5 mm × about 60 mm) of a hydrous gel made of a continuous sheet material obtained until the operation was stopped was crushed with the same meat chopper as in Example 1, and in the same process as in Example 1. Water-absorbing resin particles were produced. Of the obtained water-absorbent resin particles (7), the absorption ratio of particles having a particle size in the range of 300 μm to 600 μm was 40 (g / g), and the amount of water-soluble component was 18% by weight. As for the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1, the absorption ratio was 29 (g / g), and the SFC was 20. It was proved that the water absorption performance deteriorates if the cutting operation cannot be performed well.

Example 7
In Example 1, except that the following production conditions were changed, production of cut pieces, continuous crushing, and production of water-absorbent resin particles were performed in the same manner as in Example 1.
With the same meat chopper as in Example 1, the screw rotation speed was set to 75 rpm. The cutting capacity of the meat chopper is 4.29 t / hr with respect to the supply amount of the cut piece to the meat chopper 0.66 t / hr. The condition of supply amount ≦ disintegration discharge capacity is sufficiently satisfied. The target hydrogel particles were obtained without temporarily storing any cut pieces at the inlet of the meat chopper.

The absorption capacity of the water-absorbent resin particles (8) having a particle diameter in the range of 300 μm to 600 μm obtained through the same treatment as in Example 1 is 43 (g / g), and the water-soluble component amount is 12 wt. %Met. Subsequently, the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1 were an absorption ratio of 31 (g / g) and an SFC of 43. Water-absorbing resin particles having higher water absorption performance than that of Example 1 were obtained.
[Comparative Example 2]
In Example 1, except that the following production conditions were changed, production of cut pieces, continuous crushing, and production of water-absorbent resin particles were performed in the same manner as in Example 1.

With the same meat chopper as in Example 1, the screw rotation speed was set to 5 rpm. For the supply amount of cut pieces to the meat chopper 0.66 t / hr, the meat chopper has a disintegration and discharge capacity of 0.29 t / hr. Supply quantity> crushing discharge capacity, and the condition of supply quantity ≦ crushing discharge capacity is not satisfied. Since the amount of pulverization and discharge was too small compared to the supply amount of the continuous sheet, the biting state in the meat chopper was bad, and the cut pieces were accumulated in the inlet. The residence in the meat chopper was too long, and water-containing gel particles kneaded in the meat chopper were obtained.
The water-absorbent resin particles (9) having a particle diameter in the range of 300 μm to 600 μm obtained through the same treatment as in Example 1 have an absorption ratio of 41 (g / g) and a water-soluble component amount of 17% by weight. Met. Next, the physical properties of the heat-treated product obtained by performing the same heat treatment as in Example 1 were an absorption ratio of 29 (g / g) and an SFC of 30. Compared to Example 1, the water absorption performance is reduced.

[Comparative Example 3]
In Example 1, except that the following production conditions were changed, production of cut pieces, continuous crushing, and production of water-absorbent resin particles were performed in the same manner as in Example 1.
A continuous sheet having a sheet width of about 80 cm and a sheet thickness of 2 to 20 mm was continuously fed to the same meat chopper as in Example 1 without passing through a slitter device and a cutting device and without cutting edges. The screw speed was set to 50 rpm.
Since the speed of crushing and discharging is too high compared with the supply speed of the continuous sheet, the continuously input continuous sheet is torn off, and the re-input of the cut sheet cannot be controlled, so that the continuous operation cannot be performed.

Example 8
Basically, the same apparatus and processes as those in Example 1 were adopted, and some of the apparatus configurations and processes were changed. The difference will be mainly described.
<Manufacture of cut pieces>
A continuous sheet made of a hydrogel sheet manufactured in the same process as in Example 1 was transported by a transport belt without using a slitter device, and a continuous sheet suspended vertically was supplied to a cutting device. The cutting device basically has the same structure as that of the first embodiment. A nozzle for spraying water and a device for supplying water to the spray nozzle were installed in each of the fixed blade and the rotary blade. The amount of water sprayed was about 1300 cc / min. The rotation speed of the rotary blade was set to 30 rpm, and the continuous sheet was continuously cut every 15 cm in the length direction. As a result, a rectangular cut piece of about 80 cm × 15 cm was obtained.

In the cutting device, no continuous sheet was observed. Even after operation for a long time, no adhesion was observed. The sharpness of cutting by the rotary blade and the fixed blade did not decrease over time.
<Continuous cracking>
The cut piece obtained in the previous step was used the same meat chopper as in Example 1, and the screw rotation speed was set to 85 rpm. The supply amount of the cut piece to the meat chopper was 0.74 t / hr. This supply amount is an amount obtained by adding the supply amount 0.66 t / hr of the hydrogel sheet supplied to the cutting step and the supply amount 0.08 t / hr of the water sprayed in the cutting step. The processing capacity of the hydrogel particles that can be crushed and discharged by the meat chopper is 4.86 t / hr. The condition of supply amount ≦ crushing discharge capacity is sufficiently satisfied. Cut pieces did not accumulate temporarily at the inlet of the meat chopper, and the processing was smooth. The desired hydrogel particles were obtained satisfactorily.

<Production of water-absorbent resin particles>
The water-containing gel particles obtained in the previous step were subjected to the same treatment as in Example 1 to obtain water absorbent resin particles (10). Among the water-absorbent resin particles (10) obtained, the particle group having a particle size of 300 μm to 600 μm had an absorption ratio of 43 (g / g). The amount of water-soluble component was 12% by weight. The SFC was 43. The water-absorbent resin particles are more excellent in water absorption performance than Example 1.

Overall configuration diagram of a manufacturing apparatus representing an embodiment of the present invention Front view seen from the front side of the continuous sheet The perspective view (a) and front view (b) which show the blade part structure of a cutting device Sectional drawing which shows another embodiment of a cutting device Detailed structure diagram of slitter device The block diagram of the cutting operation part showing another embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 High concentration hydrogel continuous sheet 12 Cut piece 14 Hydrous gel particle 20 Slitter device 22 Receiving roll 23 Groove 24 Disc-shaped rotary blade 26, 38 Spray nozzle 30 Cutting device 32 Plate-shaped fixed blade 34 Rotary drum 36 Plate-shaped rotary blade 40 Continuous crusher 42 Input port 46 Screw part 48 Extruded perforated plate C Engagement position x Clearance

Claims (13)

A method for producing water-absorbing resin particles by obtaining water-containing gel particles from a continuous sheet of high-concentration water-containing gel-like cross-linked polymer, followed by drying,
The continuous sheet is a sheet having a solid content concentration of 50 to 80% by weight obtained by polymerizing a monomer aqueous solution containing a monomer component mainly composed of acrylic acid and / or acrylate and an internal crosslinking agent. Yes,
(A) a step of cutting the continuous sheet in the length direction to obtain cut pieces by cutting every 10 to 100 cm in the length direction of the continuous sheet;
The cut pieces obtained in the previous step (a) are continuously supplied to the continuous crushing apparatus, and the supply amount of the cut pieces and the crushing and discharging capacity of the continuous crushing apparatus are: (B) a step of continuously crushing and discharging under the conditions to obtain the hydrogel particles;
Including
The step (a) includes a step (a-3) of supplying a medium selected from the group consisting of water, warm water and water vapor to a cutting means for cutting the continuous sheet. Particle production method.   The method for producing water-absorbent resin particles according to claim 1, wherein the internal crosslinking agent is used in an amount of 0.005 to 2 mol% with respect to the monomer component.   In the step (a), the running direction of the continuous sheet with a fixed blade fixedly arranged so as to cross in the width direction on one side of the continuous sheet and an axis traversing in the width direction on the opposite side of the continuous sheet as a rotation center The manufacturing method of the water absorbing resin particle of Claim 1 or 2 which cut | disconnects a continuous sheet to a length direction by meshing | engaging with the rotary blade which rotates along.   The step (a) is a rotary blade that rotates in a plane along the running direction of the continuous sheet, and a step (a-1) of cutting the continuous sheet with a width of 10 to 100 cm in the width direction and cutting in the width direction. Cutting the continuous sheet in the length direction to obtain a cut piece having a width dimension of 10 to 100 cm and a length dimension of 10 to 100 cm (a-2). The manufacturing method of the water absorbing resin particle in any one.   The method for producing water-absorbent resin particles according to claim 4, wherein in the step (a-1), cutting is performed by a score cut method.   In the said process (b), the manufacturing method of the water absorbent resin particle in any one of Claim 1 to 5 which uses a screw extrusion-type crushing apparatus as said continuous crushing apparatus.   In the step (a), as a cutting device, a cutting device in which a water-containing gel adhesion preventing treatment is applied to a constituent member including a cutting blade for cutting the continuous sheet is used. A method for producing the water-absorbent resin particles as described.   The method for producing water-absorbent resin particles according to any one of claims 1 to 7, wherein surface crosslinking is further performed. A method for producing water-absorbing resin particles by obtaining water-containing gel particles from a continuous sheet of high-concentration water-containing gel-like cross-linked polymer, followed by drying,
The continuous sheet is a sheet having a solid content concentration of 50 to 80% by weight obtained by polymerizing a monomer aqueous solution containing a monomer component mainly composed of acrylic acid and / or acrylate and an internal crosslinking agent. Yes,
While running the continuous sheet in the length direction, the continuous blade is continuously arranged around the rotation center with the fixed blade fixedly arranged to traverse in the width direction on one side of the continuous sheet and the axis traversing in the width direction on the opposite side of the continuous sheet. Cutting the continuous sheet in the length direction by meshing with a rotating blade rotating along the running direction of the sheet to obtain a cut piece;
The cut pieces obtained in the step of obtaining the cut pieces are continuously supplied to the continuous crushing device, and the supply amount of the cut pieces and the crushing and discharging ability of the continuous crushing device are supplied amount ≦ crushing and discharging ability. A step of continuously crushing and discharging under the conditions to obtain the water-containing gel particles,
Including
The method for producing water-absorbent resin particles, wherein the step of obtaining the cut piece includes a step of supplying a medium selected from the group consisting of water, warm water and water vapor to a cutting means for cutting the continuous sheet. .   The method for producing water-absorbent resin particles according to claim 9, wherein the internal crosslinking agent is used in an amount of 0.005 to 2 mol% with respect to the monomer component.   The method for producing water absorbent resin particles according to claim 9 or 10, wherein the step of obtaining the cut piece includes a step of cutting the continuous sheet in the width direction by a score cut method. 12. The method according to claim 10, wherein, in the step of obtaining the cut piece, a cutting device in which a water-containing gel adhesion preventing process is applied to a constituent member including a cutting blade that cuts the continuous sheet is used as a cutting device. The manufacturing method of the water-absorbent resin particle as described in 2 .   The method for producing water-absorbent resin particles according to any one of claims 9 to 12, wherein surface crosslinking is further performed.

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