WO2022024787A1 - Method for producing water-absorbing resin particles - Google Patents

Method for producing water-absorbing resin particles Download PDF

Info

Publication number
WO2022024787A1
WO2022024787A1 PCT/JP2021/026670 JP2021026670W WO2022024787A1 WO 2022024787 A1 WO2022024787 A1 WO 2022024787A1 JP 2021026670 W JP2021026670 W JP 2021026670W WO 2022024787 A1 WO2022024787 A1 WO 2022024787A1
Authority
WO
WIPO (PCT)
Prior art keywords
drying step
drying
crosslinked polymer
water
less
Prior art date
Application number
PCT/JP2021/026670
Other languages
French (fr)
Japanese (ja)
Inventor
萌 西田
Original Assignee
住友精化株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 住友精化株式会社 filed Critical 住友精化株式会社
Priority to JP2022540169A priority Critical patent/JPWO2022024787A1/ja
Publication of WO2022024787A1 publication Critical patent/WO2022024787A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating

Definitions

  • the present invention relates to a method for producing water-absorbent resin particles.
  • a polymerization method such as an aqueous solution polymerization method in which water is used at the time of polymerization to obtain a lumpy hydrogel (for example, Patent Document 1).
  • the lumpy hydrogel contains a large amount of water used during the polymerization, and therefore needs to be dried.
  • the hydrogel when the hydrous gel is dried using a drying device, the hydrogel may adhere to the metal surface of the drying device, and it may be difficult to peel off even after the drying is completed.
  • a resin-processed metal such as fluororesin
  • a metal coated with a resin such as fluororesin has a problem that the heat transfer rate is lower than that of the original metal, so that it is generally not processed to improve the peelability such as resin coating. It is desirable that the crosslinked polymer has high peelability after drying even on the metal surface.
  • An object of the present invention is to provide a method for producing water-absorbent resin particles having excellent peelability from a metal surface of a crosslinked polymer after drying.
  • the present invention is a method for producing water-absorbent resin particles containing a crosslinked polymer, comprising a drying step of drying the crosslinked polymer, and the water content of the crosslinked polymer before the drying step is 70% by mass or less.
  • a drying step is carried out so that the rate of change in the water content of the crosslinked polymer represented by the following formula is 91.0% or more.
  • Moisture content change rate (%) [(Moisture content before drying step-Moisture content after drying step) / Moisture content before drying step] x 100
  • the drying step is performed so that the moisture content change rate is 91.0% or more and less than 100%.
  • drying step is performed so that the water content after the drying step is 10% by mass or less.
  • the crosslinked polymer may be further pulverized.
  • Water-soluble means that it exhibits a solubility in water of 5% by mass or more at 25 ° C.
  • the materials exemplified in the present specification may be used alone or in combination of two or more.
  • the content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.
  • “content of (meth) acrylic acid compound” means acrylic acid, acrylic acid salt, methacrylic acid and methacrylic acid. It means the total amount of acid salt.
  • Room temperature means 25 ° C ⁇ 2 ° C.
  • the method for producing water-absorbent resin particles containing the crosslinked polymer according to the present embodiment includes a drying step of drying the crosslinked polymer.
  • the crosslinked polymer can be obtained by polymerizing, for example, a monomer.
  • Polymerization of the monomer can be carried out using, for example, an aqueous monomer solution containing the monomer.
  • the production method according to the present embodiment is suitable when the crosslinked polymer obtained by polymerization is in the form of a water-containing gel and a polymerization method that needs to be dried, for example, an aqueous solution polymerization method is used.
  • an aqueous solution polymerization method is used.
  • the monomer may contain an ethylenically unsaturated monomer and may contain a water-soluble ethylenically unsaturated monomer.
  • the ethylenically unsaturated monomer include unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, maleic anhydride and fumaric acid, and carboxylic acid-based monomers such as salts thereof; (meth) acrylamide, Nonionic monomers such as N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate; N, N-diethylaminoethyl ( Amino group-containing unsaturated monomers such as meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylamide, and quaternary products thereof; vinyl
  • the ethylenically unsaturated monomer can contain at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof.
  • the ethylenically unsaturated monomer may contain both (meth) acrylic acid and a salt of (meth) acrylic acid.
  • Examples of the salt of unsaturated carboxylic acid ((meth) acrylic acid, etc.) include alkali metal salts (sodium salt, potassium salt, etc.), ammonium salts, and the like.
  • the ethylenically unsaturated monomer having an acid group may have an acid group neutralized in advance with an alkaline neutralizing agent.
  • alkaline neutralizing agent include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium hydrogencarbonate, potassium hydroxide and potassium carbonate; ammonia and the like.
  • the alkaline neutralizer may be used in the form of an aqueous solution in order to simplify the neutralization operation.
  • the acid group may be neutralized before the polymerization of the ethylenically unsaturated monomer as a raw material, or may be performed during or after the polymerization.
  • the degree of neutralization of the ethylenically unsaturated monomer by the alkaline neutralizer is from the viewpoint that good water absorption performance can be easily obtained by increasing the osmotic pressure, from the viewpoint of enhancing safety, and from the viewpoint of increasing the excess alkaline neutralizer. From the viewpoint of suppressing defects due to existence, 10 to 100 mol%, 30 to 90 mol%, 40 to 85 mol%, or 50 to 80 mol% is preferable.
  • the "neutralization degree” is the neutralization degree for all the acid groups of the ethylenically unsaturated monomer.
  • the content of the monomer is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, and 30% by mass based on the total mass of the aqueous monomer solution. % Or more, or 35% by mass or more.
  • the content of the monomer may be 60% by mass or less, 55% by mass or less, 50% by mass or less, less than 50% by mass, 45% by mass or less, less than 45% by mass, or 40% by mass or less. From the viewpoint of facilitating the adjustment of the water content before the drying step, which will be described later, to an appropriate range, the monomer content in the aqueous monomer solution is preferably 40% by mass or less.
  • the water content of the monomer aqueous solution is preferably 60% by mass or more.
  • the water content of the monomer aqueous solution can be calculated by the following formula.
  • Moisture content of monomeric aqueous solution (%) 100-Solid content of monomeric aqueous solution (%)
  • the solid content ratio of the monomer aqueous solution is the ratio of the compound converted into the solid content constituting the crosslinked polymer to the total amount of the monomer aqueous solution. Since the amount of components other than the monomer (for example, a cross-linking agent and a polymerization initiator) contained in the monomer aqueous solution is smaller than the amount of the monomer, the monomer content in the monomer aqueous solution May be a substantial solid content.
  • the water content of the aqueous monomer solution may be, for example, 70% by mass or less, or 65% by mass or less.
  • the content of the (meth) acrylic acid compound is based on the total amount of monomers contained in the aqueous monomer solution and / or the total amount of ethylenically unsaturated monomers contained in the aqueous monomer solution. It may be 50 mol% or more, 70 mol% or more, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more.
  • the monomer contained in the aqueous monomer solution is substantially composed of a (meth) acrylic acid compound, that is, 100 mol% of the monomer contained in the aqueous monomer solution is a (meth) acrylic acid compound. It may be in a certain aspect.
  • the monomer aqueous solution may contain a polymerization initiator.
  • the polymerization of the monomer contained in the aqueous monomer solution may be started by adding a polymerization initiator to the aqueous monomer solution and, if necessary, heating, irradiating with light or the like.
  • the polymerization initiator include a photopolymerization initiator, a radical polymerization initiator and the like, and a water-soluble radical polymerization initiator is preferable.
  • the polymerization initiator preferably contains at least one selected from the group consisting of azo compounds and peroxides from the viewpoint of easily enhancing water absorption performance.
  • Examples of the azo compound include 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride and 2,2'-azobis ⁇ 2- [N- (4-chlorophenyl) amidino] propane ⁇ dihydrochloride.
  • the azo compounds are 2,2'-azobis (2-methylpropionamide) dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2 from the viewpoint that good water absorption performance can be easily obtained.
  • Peroxides include persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl. Examples thereof include organic peroxides such as peroxyacetate, t-butylperoxyisobutyrate, and t-butylperoxypivalate.
  • the peroxide is composed of potassium persulfate, ammonium persulfate, and sodium persulfate from the viewpoint of easily obtaining good water absorption performance and easily reducing unreacted monomers contained in the water-absorbent resin particles. It is preferable to include at least one selected from the group.
  • the content of the polymerization initiator is an ethylenically unsaturated monomer (for example, (meth)) from the viewpoint of easily enhancing the water absorption performance and easily reducing the amount of unreacted monomers contained in the water-absorbent resin particles.
  • Acrylic acid compound 0.001 mmol or more, 0.005 mmol or more, 0.01 mmol or more, 0.05 mmol or more, 0.1 mmol or more, or 0.15 mmol or more is preferable with respect to 1 mol.
  • the content of the polymerization initiator is 5 mmol or less, 4 mmol or less, 2 mmol or less, 1 mmol or less, 0.9 mmol or less, from the viewpoint of easily improving the water absorption performance and avoiding a rapid polymerization reaction. It is preferably 0.7 mmol or less, 0.5 mmol or less, 0.4 mmol or less, or 0.3 mmol or less. From these viewpoints, the content of the polymerization initiator is preferably 0.001 to 5 mmol.
  • the monomer aqueous solution may contain a reducing agent.
  • a reducing agent examples include sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, L-ascorbic acid and the like.
  • a polymerization initiator and a reducing agent may be used in combination.
  • the monomer aqueous solution may contain an oxidizing agent.
  • the oxidizing agent include hydrogen peroxide, sodium perborate, perphosphate and salts thereof, potassium permanganate and the like.
  • the monomer aqueous solution may contain an internal cross-linking agent.
  • the obtained cross-linking polymer can have a cross-linking structure by the internal cross-linking agent in addition to the self-cross-linking structure by the polymerization reaction as the internal cross-linking structure.
  • Examples of the internal cross-linking agent include compounds having two or more reactive functional groups (for example, polymerizable unsaturated groups).
  • Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as (poly) ethylene glycol, (poly) propylene glycol, trimethylolpropane, glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin.
  • unsaturated polyesters obtained by reacting the above polyol with unsaturated acids (maleic acid, fumaric acid, etc.); (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin.
  • Glycidyl group-containing compounds such as diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) glycerin polyglycidyl ether, and glycidyl (meth) acrylate; bisacrylamides such as N, N'-methylenebis (meth) acrylamide; Di or tri (meth) acrylic acid esters obtained by reacting with (meth) acrylic acid; obtained by reacting polyisocyanate (tolylene diisocyanate, hexamethylene diisocyanate, etc.) with hydroxyethyl (meth) acrylic acid.
  • bisacrylamides such as N, N'-methylenebis (meth) acrylamide
  • Di or tri (meth) acrylic acid esters obtained by reacting with (meth) acrylic acid
  • polyisocyanate tolylene diisocyanate, hexamethylene diisocyanate, etc.
  • the internal cross-linking agent is (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) from the viewpoint of easily enhancing water absorption performance and excellent reactivity.
  • the content of the internal cross-linking agent is 0.001 mmol or more and 0.005 per 1 mol of ethylenically unsaturated monomer (for example, (meth) acrylic acid compound) from the viewpoint that good water absorption performance can be easily obtained. It is preferably mmol or more, 0.01 mmol or more, 0.05 mmol or more, 0.07 mmol or more, 0.09 mmol or more, 0.1 mmol or more, 0.11 mmol or more, or 0.13 mmol or more.
  • the content of the internal cross-linking agent is 5 mmol or less, 4.5 mmol or less, 4 mmol or less, 3.5 mmol or less, 3 mmol or less, 2.5 mmol or less, 2 from the viewpoint that good water absorption performance can be easily obtained. Millimole or less, 1.5 mmol or less, 1 mmol or less, 0.9 mmol or less, 0.8 mmol or less, 0.7 mmol or less, 0.5 mmol or less, 0.4 mmol or less, or 0.3 mmol or less preferable. From these viewpoints, the content of the internal cross-linking agent is preferably 0.001 to 5 mmol.
  • the monomer aqueous solution may contain additives such as a chain transfer agent, a thickener, and an inorganic filler as components different from the above-mentioned components.
  • a chain transfer agent include thiols, thiol acids, secondary alcohols, hypophosphorous acid, phosphorous acid, achlorine and the like.
  • the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyethylene glycol, polyacrylic acid, polyacrylic acid neutralized product, polyacrylamide and the like.
  • the inorganic filler include metal oxides, ceramics, and viscous minerals.
  • a polymerization method for aqueous solution polymerization there is a static polymerization method in which the monomer aqueous solution is polymerized without stirring (for example, a static state); a stirring polymerization method in which the monomer aqueous solution is polymerized while being stirred in a reaction device, or the like. Can be mentioned.
  • a static polymerization method when the polymerization is completed, a single block-shaped gel occupying substantially the same volume as the monomer aqueous solution existing in the reaction vessel can be obtained.
  • the form of polymerization may be batch, semi-continuous, continuous or the like.
  • the polymerization reaction can be carried out while continuously supplying the monomer aqueous solution to the continuous polymerization apparatus to continuously obtain a gel.
  • the polymerization temperature varies depending on the polymerization initiator used, but from the viewpoint of rapidly advancing the polymerization, increasing the productivity by shortening the polymerization time, and removing the heat of polymerization to facilitate the smooth reaction, 0 to 0 to It is preferably 130 ° C or 10 to 110 ° C.
  • the polymerization time is appropriately set depending on the type and amount of the polymerization initiator used, the reaction temperature and the like, but is preferably 1 to 200 minutes or 5 to 100 minutes.
  • the drying step may be performed. You may provide it.
  • the hydrous gel may be placed in an environment of 25 ° C. or higher and lower than the drying temperature (for example, 75 ° C. or lower) until it is subjected to the drying step.
  • the crosslinked polymer is preferably coarsely ground in advance before the drying step. That is, it is preferable that the production method according to the present embodiment includes a step of coarsely crushing the crosslinked polymer before the step of drying the crosslinked polymer. By coarsely crushing the crosslinked polymer before the drying step, drying can be performed more efficiently. In the coarse crushing step, for example, the massive hydrogel obtained by polymerization can be coarsely crushed.
  • a kneader pressurized kneader, double-armed kneader, etc.
  • a meat chopper, a cutter mill, a pharma mill, or the like can be used.
  • the lumpy hydrogel may be cut in advance into, for example, about 5 cm square, and the cut hydrogel may be subjected to coarse crushing.
  • the polymerization step is carried out by stirring polymerization with an apparatus such as a kneader, the polymerization step and the coarse crushing step may be carried out substantially at the same time.
  • the crosslinked polymer (crude gel, coarsely crushed polymer) after coarse crushing may be in the form of particles, or may have an elongated shape such that particles are connected.
  • the size of the minimum side of the coarsely crushed gel may be, for example, about 0.1 to 15 mm, preferably about 1.0 to 10 mm.
  • the size of the maximum side of the coarsely crushed gel may be about 0.1 to 200 mm, preferably about 1.0 to 150 mm.
  • the drying step is performed so that the rate of change in the water content of the crosslinked polymer represented by the following formula is 91.0% or more.
  • the water content of the crosslinked polymer before the drying step shall be 70% by mass or less.
  • Moisture content change rate (%) [(Moisture content before drying step-Moisture content after drying step) / Moisture content before drying step] x 100
  • the water content is the water content based on the wetting standard, that is, the ratio (mass%) of the water content to the total amount of the crosslinked polymer containing water.
  • the method for producing water-absorbent resin particles it is possible to improve the peelability of the crosslinked polymer (dry polymer) after the drying step from the metal surface of the drying device, for example, from the outside.
  • the crosslinked polymer can be peeled off from the metal surface by natural dropping without applying force to the crosslinked polymer.
  • the reason why such an effect is obtained is not clear, but the adhesiveness of the crosslinked polymer after the drying step is reduced by sufficient drying, and the water content before the drying step is also below a certain level, so that the crosslinked polymer is crosslinked. It is presumed that the viscosity derived from the elution of the monomers constituting the polymer can also be reduced. However, the cause is not limited to these contents.
  • drying means removing at least a part of the water contained in the crosslinked polymer by placing the crosslinked polymer in an environment of 80 ° C. or higher.
  • the crosslinked polymer is dried by placing the crosslinked polymer on a metal surface.
  • the metal surface may be, for example, a wire mesh, a metal plate having holes, or the like.
  • Metals that have undergone resin processing such as fluororesin processing tend to have a lower heat transfer rate than the original unprocessed metal, so the metal surface of the drying device is resin-processed for efficient drying. It is preferable not to do so. According to the production method according to the present embodiment, even if a metal that has not been resin-processed is used for at least a part of the metal surface of the drying device, the peelability of the crosslinked polymer from the drying device is excellent.
  • the drying temperature in the drying step is 80 ° C. or higher, and may be 90 ° C. or higher, 100 ° C. or higher, 120 ° C. or higher, 140 ° C. or higher, 160 ° C. or higher, 170 ° C. or higher, 175 ° C. or higher, or 180 ° C. or higher.
  • the drying temperature may be a temperature equal to or higher than the boiling point of water.
  • the drying temperature may be 200 ° C. or lower or 190 ° C. or lower.
  • the drying temperature may be the set temperature of the drying device or the exposure atmosphere temperature of the hydrogel in the drying step.
  • the drying step may be performed at normal pressure or reduced pressure.
  • the environmental temperature may be temporarily below the predetermined drying temperature or below 80 ° C.
  • the water content before the drying step is the water content immediately before the crosslinked polymer is subjected to the drying step.
  • Immediately before being subjected to the drying step is, for example, immediately before installing the crosslinked polymer at a predetermined place in the drying apparatus when the drying is performed using the drying apparatus.
  • the production method includes a rough crushing step of the crosslinked polymer
  • the water content of the crosslinked polymer immediately after the rough crushing may be used as the water content before the drying step.
  • the moisture content before the drying step is preferably 55% or more.
  • the moisture content before the drying step may be 68% by mass or less, 66% by mass or less, 64% by mass or less, 62% by mass or less, or 60% by mass or less.
  • the water content before the drying step can be adjusted, for example, by adjusting the water content of the monomer aqueous solution used for the polymerization of the crosslinked polymer. This is because the water content of the monomer aqueous solution affects the water content of the massive hydrogel obtained by polymerization and the water content of the crosslinked polymer after coarse crushing.
  • the polymerization step is carried out under a nitrogen stream, the gel becomes hot due to the heat of reaction during the polymerization step and the generated vapor is distilled off, and / or the massive hydrogel obtained by the polymerization is subjected to a nitrogen stream.
  • the water content before the drying step may be reduced by subjecting it to the coarse crushing step below. Further, the water content before the drying step may be increased by adding water as necessary to the lumpy water-containing gel or the crosslinked polymer after coarse crushing.
  • the drying device for drying the crosslinked polymer is set to 80 ° C. or higher, preferably a predetermined drying temperature in advance, and the drying is started at the same time as the crosslinked polymer is installed in the drying device.
  • the time of the drying step may be set so that the moisture content after drying is in an appropriate range according to the conditions such as the drying temperature.
  • the total time of the drying step may be, for example, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and may be 120 minutes or less, 90 minutes or less, or 60 minutes or less.
  • Drying of the crosslinked polymer is performed, for example, by hot air dryer, vacuum dryer, ventilation belt type dryer, ventilation band type dryer, rotary ventilation dryer, stirring dryer, fluidized layer dryer, vibration fluid dryer, vacuum drying. This can be done using a drying device such as a machine.
  • the water content after the drying step is the water content immediately after the drying step of the crosslinked polymer is completed.
  • Immediately after the completion of the drying step is, for example, immediately after the crosslinked polymer is taken out from the drying device when drying using a drying device.
  • the crosslinked polymer is pulverized after the drying step, for example, the water content of the crosslinked polymer immediately before pulverization may be used as the water content after the drying step.
  • the water content of the crosslinked polymer before the addition of water is determined by the water content after the drying step. Let it be a rate.
  • the water content after the drying step is preferably 10% by mass or less from the viewpoint of more efficiently pulverizing the crosslinked polymer after the drying step and from the viewpoint of improving the balance of the performance of the obtained water-absorbent resin particles. ..
  • the moisture content after the drying step may be 8% by mass or less, 6% by mass or less, 0.5% by mass or more, 1% by mass or more, 1.5% by mass or more, or 2% by mass or more. good.
  • the moisture content after the drying step can be reduced, for example, by increasing the drying temperature, extending the drying time, or the like.
  • the rate of change in water content before and after the drying process is 91.0% or more.
  • the water content change rate is preferably less than 100%.
  • the case where the water content change rate before and after the drying step is 100% is the case where the water content is completely removed after the drying step and the water content after the drying step is 0% by mass.
  • the rate of change in water content after the drying step may be 99.0% or less, 98.0% or less, 97.0% or less, 96.0% or less, or 95.0% or less.
  • the water content change rate before and after the drying step to 91.0% or more, for example, the water content of the monomer aqueous solution, the solid content of the monomer aqueous solution, the drying temperature, the drying time and the like can be adjusted. ..
  • the dried crosslinked polymer can be taken out from the drying apparatus. If the crosslinked polymer is placed on a metal surface during the drying step, the crosslinked polymer is stripped from the metal surface. According to the production method according to the present embodiment, the crosslinked polymer can be peeled off from the metal surface of the drying apparatus by, for example, free fall, without applying an external force.
  • the crosslinked polymer (coarsely crushed and dried polymer) after the coarse crushing and drying steps is preferably further pulverized. That is, the production method according to the present embodiment preferably includes a step of pulverizing the crosslinked polymer after the drying step. By pulverization, a particulate crosslinked polymer (polymer particles) having a smaller particle size can be obtained.
  • roller mill roller mill
  • stamp mill stamp mill
  • jet mill high-speed rotary crusher
  • hammer mill pin mill, rotor beater mill, etc.
  • container-driven mill rotary mill, vibration mill, planetary mill, etc.
  • the crusher may have an opening on the outlet side, such as a perforated plate, a screen, or a grid, for controlling the maximum particle size of the crushed particles.
  • the shape of the opening may be polygonal, circular, or the like, and the maximum diameter of the opening may be 0.1 to 5 mm, 0.3 to 3.0 mm, or 0.5 to 1.5 mm.
  • the particulate crosslinked polymer obtained by pulverization may be further classified.
  • the production method according to the present embodiment may include a step of classifying the crosslinked polymer after pulverization.
  • Classification refers to an operation of dividing a certain particle group into two or more particle groups having different particle size distributions according to the particle size. Further, a plurality of classification steps may be performed, such as crushing the classified particles again and repeating the crushing step and the classification step, or the classification step may be performed after the surface cross-linking step described later.
  • the particle classification can be performed by, for example, a screen classification, a wind power classification, or the like.
  • the particles may be granulated as needed.
  • the particle size may be adjusted so as to have a desired particle size distribution by remixing the crosslinked polymer of each particle size obtained by the classification, if necessary.
  • the method for producing water-absorbent resin particles according to the present embodiment may include a step of performing surface cross-linking of the polymer particles.
  • Surface cross-linking can be performed, for example, by adding a cross-linking agent (surface cross-linking agent) for performing surface cross-linking to the polymer particles and reacting them.
  • a cross-linking agent surface cross-linking agent
  • the surface cross-linking agent may contain, for example, two or more functional groups (reactive functional groups) having reactivity with a functional group derived from an ethylenically unsaturated monomer.
  • functional groups reactive functional groups
  • examples of the surface cross-linking agent include polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene glycol di.
  • Polyglycidyl compounds such as glycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, (poly) glycerol polyglycidyl ether; epichlorohydrin, epibromhydrin, ⁇ - Haloepoxy compounds such as methylepicrolhydrin; compounds having two or more reactive functional groups such as isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; 3-methyl-3-oxetanemethanol, 3-ethyl-3- Oxetane compounds such as oxetane methanol, 3-butyl-3-oxetane methanol, 3-methyl-3-oxetane ethanol, 3-ethyl-3-oxetan ethanol, 3-butyl-3-oxet
  • the water-absorbent resin particles obtained by the production method according to the present embodiment include the above-mentioned particulate crosslinked polymer (polymer particles).
  • the water-absorbent resin particles may be composed of only polymer particles, and may be, for example, a gel stabilizer, a metal chelating agent (ethylenediamine 4 acetic acid and its salt, diethylenetriamine 5 acetic acid and its salt, for example, diethylenetriamine 5 acetate 5 sodium and the like, etc. ), An additional component such as a fluidity improver (lubricant) may be further contained. Additional components may be placed inside, on the surface, or both of the polymer particles.
  • the water-absorbent resin particles may contain a plurality of inorganic particles arranged on the surface of the polymer particles.
  • the production method according to the present embodiment may further include a step of adhering the inorganic particles to the surface of the polymer particles.
  • the shape of the water-absorbent resin particles obtained by the production method according to the present embodiment may be, for example, a crushed shape or a shape formed by aggregating crushed particles.
  • the medium particle size of the water-absorbent resin particles may be 130 to 800 ⁇ m, 200 to 850 ⁇ m, 250 to 700 ⁇ m, 300 to 600 ⁇ m, or 300 to 450 ⁇ m.
  • the water-absorbent resin particles obtained by the production method according to the present embodiment have excellent water absorption, and are, for example, sanitary materials such as disposable diapers and sanitary products, agricultural and horticultural materials such as water-retaining agents and soil conditioners, water-stopping agents, and dew condensation prevention. It can be used in fields such as industrial materials such as agents.
  • the polymerization reaction After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. Twelve minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 88.3 ° C., and then the temperature began to decrease.
  • a stainless steel vat containing a hydrogel (crosslinked polymer in the form of a hydrogel) formed by gelation of the reaction solution is immersed in a water bath at 75 ° C., and the hydrogel is heated for 20 minutes in that state to fully complete the polymerization reaction. I let you.
  • ⁇ Manufacturing example 2> The same polymerization step as in Production Example 1 was carried out. After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. Twelve minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 85.9 ° C., and then the temperature began to decrease.
  • the polymerization step and the coarse crushing step were carried out in the same manner as in Production Example 1 except that the polyethylene film sealed on the upper part of the stainless steel vat was removed during the step.
  • the water content of the coarsely crushed gel obtained after the coarse crushing step was 57.2%.
  • ⁇ Manufacturing example 4> The same polymerization step as in Production Example 1 was carried out. After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. 14 minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 81.9 ° C., and then the temperature began to decrease.
  • Example 1 (Drying process) 60 g of the coarsely crushed gel obtained in Production Example 1 was placed uniformly within a range of 15 cm ⁇ from the center of a JIS sieve (diameter 20 cm) having an opening of 1.7 mm. Then, a metal petri dish (167 g) having a diameter of 15 cm is placed on the coarsely crushed gel, a weight of 250 g is further placed on the crushed gel, and a uniform load is applied to the entire surface of the coarsely crushed gel to sieve the coarsely crushed gel. Pressed against for 10 seconds.
  • the metal petri dish and the weight are removed, and the JIS sieve on which the above-mentioned coarsely crushed gel is placed is placed in a hot air dryer (manufactured by ADVANTEC, FV-320) set in advance at 180 ° C., and the drying step is performed for 28 minutes. To obtain a coarsely crushed dry polymer. After the JIS sieve on which the coarsely crushed and dried polymer was placed was taken out from the dryer after the drying step, the peeling rate test described later was immediately carried out.
  • a hot air dryer manufactured by ADVANTEC, FV-320
  • Examples 2 to 5 and Comparative Examples were the same as in Example 1 except that the drying time and the drying temperature were changed as shown in Table 1 using the coarsely crushed gel obtained by the production example numbers shown in Table 1. The manufacturing method of 1 to 10 was performed.
  • the water content A before the drying step and the water content B after the drying step of the measurement sample were measured by the following methods.
  • a sample of 20.0 g of the coarsely crushed gel obtained in the rough crushing step in Production Example 4, the coarsely crushed gel after mixing with ion-exchanged water
  • a sample of 20.0 g of the coarsely crushed dried polymer obtained immediately after the drying step 180 ° C., predetermined time
  • the above measurement sample is placed on a fluororesin-coated stainless steel vat (outer dimensions: 185 mm ⁇ 140 mm ⁇ height 30 mm) that has been preliminarily set to a constant amount (W1 (g)), and the total mass W2 (g) of the stainless steel vat and the measurement sample is refined. Weighed.
  • the finely weighed measurement sample was dried for 2 hours in a hot air dryer (manufactured by ADVANTEC, model: FV-320) in which the internal temperature was set to 200 ° C. while being placed on the above-mentioned stainless steel vat.
  • the amount of change in the water content (mass%) before and after the drying step was calculated by the following formula.
  • Moisture content change before and after the drying step (mass%) Moisture content before the drying step A-Moisture content after the drying step B
  • Moisture content change rate before and after the drying step (%) (Moisture content change before and after the drying step / Moisture content before the drying step A) x 100

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Analytical Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)

Abstract

Disclosed is a method for producing water-absorbing resin particles that contain a cross-linked polymer, said method including a drying step for drying a cross-linked polymer, wherein the moisture content of the cross-linked polymer before the drying step is 70 mass% or less. The drying step is carried out such that the moisture content change rate of the cross-linked polymer, represented by following expression, is 91.0% or more. The moisture content change rate (%) = [(the moisture content before the drying step －the moisture content after the drying step)/the moisture content before the drying step] × 100.

Description

吸水性樹脂粒子の製造方法Method for manufacturing water-absorbent resin particles
　本発明は、吸水性樹脂粒子の製造方法に関する。 The present invention relates to a method for producing water-absorbent resin particles.
　吸水性樹脂粒子を構成する架橋重合体を合成する方法には、重合時に水を使用し、塊状の含水ゲルが得られる水溶液重合法等の重合方法がある（例えば、特許文献１）。塊状の含水ゲルは、重合時に用いた水分を多く含むため、乾燥される必要がある。 As a method for synthesizing a crosslinked polymer constituting water-absorbent resin particles, there is a polymerization method such as an aqueous solution polymerization method in which water is used at the time of polymerization to obtain a lumpy hydrogel (for example, Patent Document 1). The lumpy hydrogel contains a large amount of water used during the polymerization, and therefore needs to be dried.
特開２０１６－３０８３２号公報Japanese Unexamined Patent Publication No. 2016-30832
　例えば乾燥装置を用いて含水ゲルを乾燥させる際に、含水ゲルが乾燥装置の金属面に付着し、乾燥終了後にも剥離が困難なことがある。乾燥装置の金属面の剥離性を向上させるためにフッ素樹脂等の樹脂加工がなされた金属が用いられることがある。しかしながら、フッ素樹脂等の樹脂コーティングがなされた金属は、元の金属に比べて伝熱率が落ちる等の問題があるため、樹脂コーティングなどの剥離性向上のための加工がなされていない一般的な金属面においても、乾燥後の架橋重合体の剥離性が高いことが望ましい。 For example, when the hydrous gel is dried using a drying device, the hydrogel may adhere to the metal surface of the drying device, and it may be difficult to peel off even after the drying is completed. In order to improve the peelability of the metal surface of the drying device, a resin-processed metal such as fluororesin may be used. However, a metal coated with a resin such as fluororesin has a problem that the heat transfer rate is lower than that of the original metal, so that it is generally not processed to improve the peelability such as resin coating. It is desirable that the crosslinked polymer has high peelability after drying even on the metal surface.
　本発明は、乾燥後の架橋重合体の金属面からの剥離性に優れた吸水性樹脂粒子の製造方法を提供することを目的とする。 An object of the present invention is to provide a method for producing water-absorbent resin particles having excellent peelability from a metal surface of a crosslinked polymer after drying.
　本発明は、架橋重合体を含む吸水性樹脂粒子の製造方法であって、架橋重合体を乾燥する乾燥工程を含み、該架橋重合体の乾燥工程前含水率が７０質量％以下であり、該乾燥工程が、下記式で示される前記架橋重合体の含水率変化率が９１．０％以上になるように行われる、方法を提供する。
　含水率変化率（％）＝［（乾燥工程前含水率－乾燥工程後含水率）／乾燥工程前含水率］×１００ The present invention is a method for producing water-absorbent resin particles containing a crosslinked polymer, comprising a drying step of drying the crosslinked polymer, and the water content of the crosslinked polymer before the drying step is 70% by mass or less. Provided is a method in which the drying step is carried out so that the rate of change in the water content of the crosslinked polymer represented by the following formula is 91.0% or more.
Moisture content change rate (%) = [(Moisture content before drying step-Moisture content after drying step) / Moisture content before drying step] x 100
　上記乾燥工程が、上記含水率変化率が９１．０％以上１００％未満となるように行われることが好ましい。 It is preferable that the drying step is performed so that the moisture content change rate is 91.0% or more and less than 100%.
　上記乾燥工程が、上記乾燥工程後含水率が１０質量％以下となるように行われることが好ましい。 It is preferable that the drying step is performed so that the water content after the drying step is 10% by mass or less.
　上記乾燥工程前に、上記架橋重合体を粗砕することを更に含むことが好ましい。 It is preferable to further include coarsely crushing the crosslinked polymer before the drying step.
　上記乾燥工程後に、上記架橋重合体を粉砕することを更に含んでもよい。 After the drying step, the crosslinked polymer may be further pulverized.
　本発明により、乾燥後の架橋重合体の金属面からの剥離性に優れた吸水性樹脂粒子の製造方法を提供することができる。 INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing water-absorbent resin particles having excellent peelability from a metal surface of a crosslinked polymer after drying.
　以下、本発明の実施形態について詳細に説明する。但し、本発明は、以下の実施形態に限定されるものではなく、その要旨の範囲内で種々変形して実施することができる。 Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.
　本明細書において、「アクリル」及び「メタクリル」を合わせて「（メタ）アクリル」と表記する。「アクリレート」及び「メタクリレート」も同様に「（メタ）アクリレート」と表記する。「ポリエチレングリコール」及び「エチレングリコール」を合わせて「（ポリ）エチレングリコール」と表記する。「（ポリ）」を含む他の表現についても同様である。本明細書に段階的に記載されている数値範囲において、ある段階の数値範囲の上限値又は下限値は、他の段階の数値範囲の上限値又は下限値と任意に組み合わせることができる。本明細書に記載されている数値範囲において、その数値範囲の上限値又は下限値は、実施例に示されている値に置き換えてもよい。「水溶性」とは、２５℃において水に５質量％以上の溶解性を示すことをいう。本明細書に例示する材料は、単独で用いられてもよく、２種以上を組み合わせて用いられてもよい。組成物中の各成分の含有量は、組成物中に各成分に該当する物質が複数存在する場合、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。（メタ）アクリル酸及びその塩からなる群より選ばれる少なくとも一種の（メタ）アクリル酸化合物に関して、「（メタ）アクリル酸化合物の含有量」とは、アクリル酸、アクリル酸塩、メタクリル酸及びメタクリル酸塩の合計量を意味する。「室温」は、２５℃±２℃を意味する。 In this specification, "acrylic" and "methacrylic" are collectively referred to as "(meth) acrylic". Similarly, "acrylate" and "methacrylate" are also referred to as "(meth) acrylate". "Polyethylene glycol" and "ethylene glycol" are collectively referred to as "(poly) ethylene glycol". The same applies to other expressions including "(poly)". Within the numerical range described stepwise herein, the upper or lower limit of the numerical range at one stage may be optionally combined with the upper or lower limit of the numerical range at another stage. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "Water-soluble" means that it exhibits a solubility in water of 5% by mass or more at 25 ° C. The materials exemplified in the present specification may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. With respect to at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof, "content of (meth) acrylic acid compound" means acrylic acid, acrylic acid salt, methacrylic acid and methacrylic acid. It means the total amount of acid salt. "Room temperature" means 25 ° C ± 2 ° C.
　本実施形態に係る架橋重合体を含む吸水性樹脂粒子の製造方法は、架橋重合体を乾燥する乾燥工程を含む。 The method for producing water-absorbent resin particles containing the crosslinked polymer according to the present embodiment includes a drying step of drying the crosslinked polymer.
［重合］
　本実施形態に係る製造方法において、架橋重合体は、例えば単量体を重合して得ることができる。単量体の重合は、例えば単量体を含む単量体水溶液を用いて行うことができる。 [polymerization]
In the production method according to the present embodiment, the crosslinked polymer can be obtained by polymerizing, for example, a monomer. Polymerization of the monomer can be carried out using, for example, an aqueous monomer solution containing the monomer.
　本実施形態に係る製造方法は、重合して得られる架橋重合体が含水ゲル状であり、乾燥する必要がある重合方法、例えば水溶液重合法を用いる場合に適している。以下、水溶液重合法を用いた場合について説明する。 The production method according to the present embodiment is suitable when the crosslinked polymer obtained by polymerization is in the form of a water-containing gel and a polymerization method that needs to be dried, for example, an aqueous solution polymerization method is used. Hereinafter, the case where the aqueous solution polymerization method is used will be described.
　単量体は、エチレン性不飽和単量体を含んでよく、水溶性エチレン性不飽和単量体を含んでよい。エチレン性不飽和単量体としては、（メタ）アクリル酸、マレイン酸、無水マレイン酸、フマル酸等の不飽和カルボン酸、及び、その塩などのカルボン酸系単量体；（メタ）アクリルアミド、Ｎ，Ｎ－ジメチル（メタ）アクリルアミド、２－ヒドロキシエチル（メタ）アクリレート、Ｎ－メチロール（メタ）アクリルアミド、ポリエチレングリコールモノ（メタ）アクリレート等の非イオン性単量体；Ｎ，Ｎ－ジエチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ－ジエチルアミノプロピル（メタ）アクリレート、ジエチルアミノプロピル（メタ）アクリルアミド等のアミノ基含有不飽和単量体、及び、その第４級化物；ビニルスルホン酸、スチレンスルホン酸、２－（メタ）アクリルアミド－２－メチルプロパンスルホン酸、２－（メタ）アクリロイルエタンスルホン酸、及び、それらの塩等のスルホン酸系単量体などが挙げられる。エチレン性不飽和単量体は、（メタ）アクリル酸及びその塩からなる群より選ばれる少なくとも一種の（メタ）アクリル酸化合物を含むことができる。エチレン性不飽和単量体は、（メタ）アクリル酸、及び、（メタ）アクリル酸の塩の双方を含んでよい。不飽和カルボン酸（（メタ）アクリル酸等）の塩としては、アルカリ金属塩（ナトリウム塩、カリウム塩等）、アンモニウム塩などが挙げられる。 The monomer may contain an ethylenically unsaturated monomer and may contain a water-soluble ethylenically unsaturated monomer. Examples of the ethylenically unsaturated monomer include unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, maleic anhydride and fumaric acid, and carboxylic acid-based monomers such as salts thereof; (meth) acrylamide, Nonionic monomers such as N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate; N, N-diethylaminoethyl ( Amino group-containing unsaturated monomers such as meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylamide, and quaternary products thereof; vinyl sulfonic acid, styrene sulfonic acid, 2- Examples thereof include (meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, and sulfonic acid-based monomers such as salts thereof. The ethylenically unsaturated monomer can contain at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof. The ethylenically unsaturated monomer may contain both (meth) acrylic acid and a salt of (meth) acrylic acid. Examples of the salt of unsaturated carboxylic acid ((meth) acrylic acid, etc.) include alkali metal salts (sodium salt, potassium salt, etc.), ammonium salts, and the like.
　酸基を有するエチレン性不飽和単量体（例えば（メタ）アクリル酸）は、酸基が予めアルカリ性中和剤により中和されていてよい。アルカリ性中和剤としては、水酸化ナトリウム、炭酸ナトリウム、炭酸水素ナトリウム、水酸化カリウム、炭酸カリウム等のアルカリ金属塩；アンモニアなどが挙げられる。アルカリ性中和剤は、中和操作を簡便化するために水溶液の状態にして用いてもよい。酸基の中和は、原料であるエチレン性不飽和単量体の重合前に行ってもよく、重合中又は重合後に行ってもよい。 The ethylenically unsaturated monomer having an acid group (for example, (meth) acrylic acid) may have an acid group neutralized in advance with an alkaline neutralizing agent. Examples of the alkaline neutralizing agent include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium hydrogencarbonate, potassium hydroxide and potassium carbonate; ammonia and the like. The alkaline neutralizer may be used in the form of an aqueous solution in order to simplify the neutralization operation. The acid group may be neutralized before the polymerization of the ethylenically unsaturated monomer as a raw material, or may be performed during or after the polymerization.
　アルカリ性中和剤によるエチレン性不飽和単量体の中和度は、浸透圧を高めることで、良好な吸水性能が得られやすい観点、安全性を高める観点、及び、余剰のアルカリ性中和剤の存在に起因する不具合を抑制する観点から、１０～１００モル％、３０～９０モル％、４０～８５モル％、又は、５０～８０モル％が好ましい。「中和度」は、エチレン性不飽和単量体が有する全ての酸基に対する中和度とする。 The degree of neutralization of the ethylenically unsaturated monomer by the alkaline neutralizer is from the viewpoint that good water absorption performance can be easily obtained by increasing the osmotic pressure, from the viewpoint of enhancing safety, and from the viewpoint of increasing the excess alkaline neutralizer. From the viewpoint of suppressing defects due to existence, 10 to 100 mol%, 30 to 90 mol%, 40 to 85 mol%, or 50 to 80 mol% is preferable. The "neutralization degree" is the neutralization degree for all the acid groups of the ethylenically unsaturated monomer.
　単量体（例えば（メタ）アクリル酸化合物）の含有量は、単量体水溶液の全質量を基準として、１０質量％以上、１５質量％以上、２０質量％以上、２５質量％以上、３０質量％以上、又は３５質量％以上であってよい。単量体の含有量は、６０質量％以下、５５質量％以下、５０質量％以下、５０質量％未満、４５質量％以下、４５質量％未満、又は４０質量％以下であってよい。後述の乾燥工程前含水率を適切な範囲に調整しやすくする観点から、単量体水溶液における単量体含有量は、４０質量％以下であることが好ましい。 The content of the monomer (for example, (meth) acrylic acid compound) is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, and 30% by mass based on the total mass of the aqueous monomer solution. % Or more, or 35% by mass or more. The content of the monomer may be 60% by mass or less, 55% by mass or less, 50% by mass or less, less than 50% by mass, 45% by mass or less, less than 45% by mass, or 40% by mass or less. From the viewpoint of facilitating the adjustment of the water content before the drying step, which will be described later, to an appropriate range, the monomer content in the aqueous monomer solution is preferably 40% by mass or less.
　重合反応において、自己架橋等の副反応を抑制する観点、後述の粗砕工程において含水ゲルを粗砕しやすい硬さに調整する観点、及び、後述の乾燥工程において含水ゲル中の固形性分の劣化を抑制する観点から、単量体水溶液の水分率は、６０質量％以上であることが好ましい。単量体水溶液の水分率は以下の式により求めることができる。
　単量体水溶液の水分率（％）＝１００－単量体水溶液の固形分率（％）
　単量体水溶液の固形分率は、架橋重合体を構成する固形分に転化する化合物の、単量体水溶液全量に対する割合である。単量体水溶液に含まれる単量体以外の成分（例えば架橋剤、重合開始剤）の量は、単量体の量に比べて微小であるため、単量体水溶液中の単量体含有量を、実質的な固形分量としてもよい。単量体水溶液の水分率は、例えば７０質量％以下、又は６５質量％以下であってもよい。 In the polymerization reaction, from the viewpoint of suppressing side reactions such as self-crosslinking, from the viewpoint of adjusting the hardness of the hydrous gel to be easy to coarsely crush in the coarse crushing step described later, and from the viewpoint of adjusting the hardness of the hydrous gel to be easy to coarsely crush, and the solid content in the hydrous gel in the drying step described later. From the viewpoint of suppressing deterioration, the water content of the monomer aqueous solution is preferably 60% by mass or more. The water content of the monomer aqueous solution can be calculated by the following formula.
Moisture content of monomeric aqueous solution (%) = 100-Solid content of monomeric aqueous solution (%)
The solid content ratio of the monomer aqueous solution is the ratio of the compound converted into the solid content constituting the crosslinked polymer to the total amount of the monomer aqueous solution. Since the amount of components other than the monomer (for example, a cross-linking agent and a polymerization initiator) contained in the monomer aqueous solution is smaller than the amount of the monomer, the monomer content in the monomer aqueous solution May be a substantial solid content. The water content of the aqueous monomer solution may be, for example, 70% by mass or less, or 65% by mass or less.
　（メタ）アクリル酸化合物の含有量は、単量体水溶液に含有される単量体の合計量、及び／又は、単量体水溶液に含有されるエチレン性不飽和単量体の合計量を基準として、５０モル％以上、７０モル％以上、９０モル％以上、９５モル％以上、９７モル％以上、又は、９９モル％以上であってよい。単量体水溶液に含有される単量体は、実質的に（メタ）アクリル酸化合物からなる態様、すなわち単量体水溶液に含有される単量体の１００モル％が（メタ）アクリル酸化合物である態様であってもよい。 The content of the (meth) acrylic acid compound is based on the total amount of monomers contained in the aqueous monomer solution and / or the total amount of ethylenically unsaturated monomers contained in the aqueous monomer solution. It may be 50 mol% or more, 70 mol% or more, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more. The monomer contained in the aqueous monomer solution is substantially composed of a (meth) acrylic acid compound, that is, 100 mol% of the monomer contained in the aqueous monomer solution is a (meth) acrylic acid compound. It may be in a certain aspect.
　単量体水溶液は、重合開始剤を含有してよい。単量体水溶液に含まれる単量体の重合は、単量体水溶液に重合開始剤を添加し、必要により加熱、光照射等を行うことで開始してよい。重合開始剤としては、光重合開始剤、ラジカル重合開始剤等が挙げられ、水溶性ラジカル重合開始剤が好ましい。重合開始剤は、吸水性能を高めやすい観点から、アゾ系化合物及び過酸化物からなる群より選ばれる少なくとも一種を含むことが好ましい。 The monomer aqueous solution may contain a polymerization initiator. The polymerization of the monomer contained in the aqueous monomer solution may be started by adding a polymerization initiator to the aqueous monomer solution and, if necessary, heating, irradiating with light or the like. Examples of the polymerization initiator include a photopolymerization initiator, a radical polymerization initiator and the like, and a water-soluble radical polymerization initiator is preferable. The polymerization initiator preferably contains at least one selected from the group consisting of azo compounds and peroxides from the viewpoint of easily enhancing water absorption performance.
　アゾ系化合物としては、２，２’－アゾビス［２－（Ｎ－フェニルアミジノ）プロパン］二塩酸塩、２，２’－アゾビス｛２－［Ｎ－（４－クロロフェニル）アミジノ］プロパン｝二塩酸塩、２，２’－アゾビス｛２－［Ｎ－（４－ヒドロキシフェニル）アミジノ］プロパン｝二塩酸塩、２，２’－アゾビス［２－（Ｎ－ベンジルアミジノ）プロパン］二塩酸塩、２，２’－アゾビス［２－（Ｎ－アリルアミジノ）プロパン］二塩酸塩、２，２’－アゾビス（２－アミジノプロパン）二塩酸塩、２，２’－アゾビス｛２－［Ｎ－（２－ヒドロキシエチル）アミジノ］プロパン｝二塩酸塩、２，２’－アゾビス［２－（５－メチル－２－イミダゾリン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス［２－（２－イミダゾリン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス［２－（４，５，６，７－テトラヒドロ－１Ｈ－１，３－ジアゼピン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス［２－（５－ヒドロキシ－３，４，５，６－テトラヒドロピリミジン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス｛２－［１－（２－ヒドロキシエチル）－２－イミダゾリン－２－イル］プロパン｝二塩酸塩、２，２’－アゾビス［２－（２－イミダゾリン－２－イル）プロパン］二硫酸塩二水和物、２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン］四水和物、２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）プロピオンアミド］等が挙げられる。アゾ系化合物は、良好な吸水性能が得られやすい観点から、２，２’－アゾビス（２－メチルプロピオンアミド）二塩酸塩、２，２’－アゾビス（２－アミジノプロパン）二塩酸塩、２，２’－アゾビス｛２－［１－（２－ヒドロキシエチル）－２－イミダゾリン－２－イル］プロパン｝二塩酸塩、及び、２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン］四水和物からなる群より選ばれる少なくとも一種を含むことが好ましい。 Examples of the azo compound include 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride and 2,2'-azobis {2- [N- (4-chlorophenyl) amidino] propane} dihydrochloride. Salt, 2,2'-azobis {2- [N- (4-hydroxyphenyl) amidino] propane} dihydrochloride, 2,2'-azobis [2- (N-benzylamidino) propane] dihydrochloride, 2 , 2'-azobis [2- (N-allylamidino) propane] dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis {2- [N- (2) -Hydroxyethyl) amidino] propane} dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2-( 2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (4,5,6,7-tetrahydro-1H-1,3-diazepine-2-yl) propane] dihydrochloride Salt, 2,2'-azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl) propane] dihydrochloride, 2,2'-azobis {2- [1-( 2-Hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2, 2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate, 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] and the like can be mentioned. Be done. The azo compounds are 2,2'-azobis (2-methylpropionamide) dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2 from the viewpoint that good water absorption performance can be easily obtained. , 2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, and 2,2'-azobis [N- (2-carboxyethyl)- 2-Methylpropionamidine] It is preferable to contain at least one selected from the group consisting of tetrahydrate.
　過酸化物としては、過硫酸カリウム、過硫酸アンモニウム、過硫酸ナトリウム等の過硫酸塩類；メチルエチルケトンパーオキシド、メチルイソブチルケトンパーオキシド、ジ－ｔ－ブチルパーオキシド、ｔ－ブチルクミルパーオキシド、ｔ－ブチルパーオキシアセテート、ｔ－ブチルパーオキシイソブチレート、ｔ－ブチルパーオキシピバレート等の有機過酸化物類などが挙げられる。過酸化物は、良好な吸水性能が得られやすい観点、及び、吸水性樹脂粒子に含まれる未反応単量体を低減しやすい観点から、過硫酸カリウム、過硫酸アンモニウム、及び、過硫酸ナトリウムからなる群より選ばれる少なくとも一種を含むことが好ましい。 Peroxides include persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl. Examples thereof include organic peroxides such as peroxyacetate, t-butylperoxyisobutyrate, and t-butylperoxypivalate. The peroxide is composed of potassium persulfate, ammonium persulfate, and sodium persulfate from the viewpoint of easily obtaining good water absorption performance and easily reducing unreacted monomers contained in the water-absorbent resin particles. It is preferable to include at least one selected from the group.
　重合開始剤の含有量は、吸水性能を高めやすい観点、及び、吸水性樹脂粒子に含まれる未反応の単量体量を低減しやすい観点から、エチレン性不飽和単量体（例えば（メタ）アクリル酸化合物）１モルに対して、０．００１ミリモル以上、０．００５ミリモル以上、０．０１ミリモル以上、０．０５ミリモル以上、０．１ミリモル以上、又は０．１５ミリモル以上が好ましい。重合開始剤の含有量は、吸水性能を高めやすい観点、及び、急激な重合反応を回避しやすい観点から、５ミリモル以下、４ミリモル以下、２ミリモル以下、１ミリモル以下、０．９ミリモル以下、０．７ミリモル以下、０．５ミリモル以下、０．４ミリモル以下、又は０．３ミリモル以下が好ましい。これらの観点から、重合開始剤の含有量は、０．００１～５ミリモルが好ましい。 The content of the polymerization initiator is an ethylenically unsaturated monomer (for example, (meth)) from the viewpoint of easily enhancing the water absorption performance and easily reducing the amount of unreacted monomers contained in the water-absorbent resin particles. Acrylic acid compound) 0.001 mmol or more, 0.005 mmol or more, 0.01 mmol or more, 0.05 mmol or more, 0.1 mmol or more, or 0.15 mmol or more is preferable with respect to 1 mol. The content of the polymerization initiator is 5 mmol or less, 4 mmol or less, 2 mmol or less, 1 mmol or less, 0.9 mmol or less, from the viewpoint of easily improving the water absorption performance and avoiding a rapid polymerization reaction. It is preferably 0.7 mmol or less, 0.5 mmol or less, 0.4 mmol or less, or 0.3 mmol or less. From these viewpoints, the content of the polymerization initiator is preferably 0.001 to 5 mmol.
　単量体水溶液は、還元剤を含有してよい。還元剤としては、亜硫酸ナトリウム、亜硫酸水素ナトリウム、硫酸第１鉄、Ｌ－アスコルビン酸等が挙げられる。重合開始剤と還元剤とを併用してもよい。 The monomer aqueous solution may contain a reducing agent. Examples of the reducing agent include sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, L-ascorbic acid and the like. A polymerization initiator and a reducing agent may be used in combination.
　単量体水溶液は、酸化剤を含有してよい。酸化剤としては、過酸化水素、過ホウ酸ナトリウム、過リン酸及びその塩、過マンガン酸カリウム等が挙げられる。 The monomer aqueous solution may contain an oxidizing agent. Examples of the oxidizing agent include hydrogen peroxide, sodium perborate, perphosphate and salts thereof, potassium permanganate and the like.
　単量体水溶液は、内部架橋剤を含有してよい。内部架橋剤を用いることにより、得られる架橋重合体が、その内部架橋構造として、重合反応による自己架橋構造に加え、内部架橋剤による架橋構造を有することができる。 The monomer aqueous solution may contain an internal cross-linking agent. By using the internal cross-linking agent, the obtained cross-linking polymer can have a cross-linking structure by the internal cross-linking agent in addition to the self-cross-linking structure by the polymerization reaction as the internal cross-linking structure.
　内部架橋剤としては、反応性官能基（例えば重合性不飽和基）を２個以上有する化合物等が挙げられる。内部架橋剤としては、（ポリ）エチレングリコール、（ポリ）プロピレングリコール、トリメチロールプロパン、グリセリンポリオキシエチレングリコール、ポリオキシプロピレングリコール、（ポリ）グリセリン等のポリオールのジ又はトリ（メタ）アクリル酸エステル類；上記ポリオールと不飽和酸（マレイン酸、フマル酸等）とを反応させて得られる不飽和ポリエステル類；（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）プロピレングリコールジグリシジルエーテル、（ポリ）グリセリンジグリシジルエーテル、（ポリ）グリセリントリグリシジルエーテル、（ポリ）グリセリンポリグリシジルエーテル、グリシジル（メタ）アクリレート等のグリシジル基含有化合物；Ｎ，Ｎ’－メチレンビス（メタ）アクリルアミド等のビスアクリルアミド類；ポリエポキシドと（メタ）アクリル酸とを反応させて得られるジ又はトリ（メタ）アクリル酸エステル類；ポリイソシアネート（トリレンジイソシアネート、ヘキサメチレンジイソシアネート等）と（メタ）アクリル酸ヒドロキシエチルとを反応させて得られるジ（メタ）アクリル酸カルバミルエステル類；アリル化澱粉；アリル化セルロース；ジアリルフタレート；Ｎ，Ｎ’，Ｎ”－トリアリルイソシアヌレート；ジビニルベンゼン；ペンタエリスリトール；エチレンジアミン；ポリエチレンイミンなどが挙げられる。内部架橋剤は、吸水性能を高めやすい観点、及び、反応性に優れる観点から、（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）プロピレングリコールジグリシジルエーテル、（ポリ）グリセリントリグリシジルエーテル、（ポリ）グリセリンジグリシジルエーテル、ポリエチレングリコールジアクリレート、（ポリ）プロピレングリコールジアクリレート、トリメチロールプロパントリアクリレート、グリセロールトリアクリレート、及びトリメチロールプロパンジアクリレートからなる群より選ばれる少なくとも一種を含むことが好ましい。 Examples of the internal cross-linking agent include compounds having two or more reactive functional groups (for example, polymerizable unsaturated groups). Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as (poly) ethylene glycol, (poly) propylene glycol, trimethylolpropane, glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin. Classes; unsaturated polyesters obtained by reacting the above polyol with unsaturated acids (maleic acid, fumaric acid, etc.); (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin. Glycidyl group-containing compounds such as diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) glycerin polyglycidyl ether, and glycidyl (meth) acrylate; bisacrylamides such as N, N'-methylenebis (meth) acrylamide; Di or tri (meth) acrylic acid esters obtained by reacting with (meth) acrylic acid; obtained by reacting polyisocyanate (tolylene diisocyanate, hexamethylene diisocyanate, etc.) with hydroxyethyl (meth) acrylic acid. Di (meth) acrylic acid carbamyl esters; allylated starch; allylated cellulose; diallyl phthalate; N, N', N "-triallyl isocyanurate; divinylbenzene; pentaerythritol; ethylenediamine; polyethyleneimine and the like. The internal cross-linking agent is (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) from the viewpoint of easily enhancing water absorption performance and excellent reactivity. It is preferable to contain at least one selected from the group consisting of glycerin diglycidyl ether, polyethylene glycol diacrylate, (poly) propylene glycol diacrylate, trimethylol propanetriacrylate, glycerol triacrylate, and trimethylol propanediacrylate.
　内部架橋剤の含有量は、良好な吸水性能が得られやすい観点から、エチレン性不飽和単量体（例えば（メタ）アクリル酸化合物）１モルに対して、０．００１ミリモル以上、０．００５ミリモル以上、０．０１ミリモル以上、０．０５ミリモル以上、０．０７ミリモル以上、０．０９ミリモル以上、０．１ミリモル以上、０．１１ミリモル以上、又は０．１３ミリモル以上が好ましい。内部架橋剤の含有量は、良好な吸水性能が得られやすい観点から、５ミリモル以下、４．５ミリモル以下、４ミリモル以下、３．５ミリモル以下、３ミリモル以下、２．５ミリモル以下、２ミリモル以下、１．５ミリモル以下、１ミリモル以下、０．９ミリモル以下、０．８ミリモル以下、０．７ミリモル以下、０．５ミリモル以下、０．４ミリモル以下、又は０．３ミリモル以下が好ましい。これらの観点から、内部架橋剤の含有量は、０．００１～５ミリモルが好ましい。 The content of the internal cross-linking agent is 0.001 mmol or more and 0.005 per 1 mol of ethylenically unsaturated monomer (for example, (meth) acrylic acid compound) from the viewpoint that good water absorption performance can be easily obtained. It is preferably mmol or more, 0.01 mmol or more, 0.05 mmol or more, 0.07 mmol or more, 0.09 mmol or more, 0.1 mmol or more, 0.11 mmol or more, or 0.13 mmol or more. The content of the internal cross-linking agent is 5 mmol or less, 4.5 mmol or less, 4 mmol or less, 3.5 mmol or less, 3 mmol or less, 2.5 mmol or less, 2 from the viewpoint that good water absorption performance can be easily obtained. Millimole or less, 1.5 mmol or less, 1 mmol or less, 0.9 mmol or less, 0.8 mmol or less, 0.7 mmol or less, 0.5 mmol or less, 0.4 mmol or less, or 0.3 mmol or less preferable. From these viewpoints, the content of the internal cross-linking agent is preferably 0.001 to 5 mmol.
　単量体水溶液は、必要に応じて、上述の各成分とは異なる成分として、連鎖移動剤、増粘剤、無機フィラー等の添加剤を含有してよい。連鎖移動剤としては、チオール類、チオール酸類、第２級アルコール類、次亜リン酸、亜リン酸、アクロレイン等が挙げられる。増粘剤としては、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、メチルセルロース、ポリエチレングリコール、ポリアクリル酸、ポリアクリル酸中和物、ポリアクリルアミド等が挙げられる。無機フィラーとしては、金属酸化物、セラミック、粘度鉱物等が挙げられる。 If necessary, the monomer aqueous solution may contain additives such as a chain transfer agent, a thickener, and an inorganic filler as components different from the above-mentioned components. Examples of the chain transfer agent include thiols, thiol acids, secondary alcohols, hypophosphorous acid, phosphorous acid, achlorine and the like. Examples of the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyethylene glycol, polyacrylic acid, polyacrylic acid neutralized product, polyacrylamide and the like. Examples of the inorganic filler include metal oxides, ceramics, and viscous minerals.
　水溶液重合の重合方式としては、単量体水溶液を撹拌しない状態（例えば、静置状態）で重合する静置重合方式；反応装置内で単量体水溶液を撹拌しながら重合する撹拌重合方式等が挙げられる。静置重合方式では、重合完了時、反応容器中に存在した単量体水溶液と略同じ体積を占める単一のブロック状のゲルが得られる。 As a polymerization method for aqueous solution polymerization, there is a static polymerization method in which the monomer aqueous solution is polymerized without stirring (for example, a static state); a stirring polymerization method in which the monomer aqueous solution is polymerized while being stirred in a reaction device, or the like. Can be mentioned. In the static polymerization method, when the polymerization is completed, a single block-shaped gel occupying substantially the same volume as the monomer aqueous solution existing in the reaction vessel can be obtained.
　重合の形態は、回分、半連続、連続等であってよい。例えば、静置重合方式を連続重合にて行う場合、連続重合装置に単量体水溶液を連続的に供給しながら重合反応を行い、連続的にゲルを得ることができる。 The form of polymerization may be batch, semi-continuous, continuous or the like. For example, when the static polymerization method is carried out by continuous polymerization, the polymerization reaction can be carried out while continuously supplying the monomer aqueous solution to the continuous polymerization apparatus to continuously obtain a gel.
　重合温度は、使用する重合開始剤によって異なるが、重合を迅速に進行させ、重合時間を短くすることにより生産性を高めるとともに、重合熱を除去して円滑に反応を行いやすい観点から、０～１３０℃又は１０～１１０℃が好ましい。重合時間は、使用する重合開始剤の種類及び量、反応温度等に応じて適宜設定されるが、１～２００分又は５～１００分が好ましい。 The polymerization temperature varies depending on the polymerization initiator used, but from the viewpoint of rapidly advancing the polymerization, increasing the productivity by shortening the polymerization time, and removing the heat of polymerization to facilitate the smooth reaction, 0 to 0 to It is preferably 130 ° C or 10 to 110 ° C. The polymerization time is appropriately set depending on the type and amount of the polymerization initiator used, the reaction temperature and the like, but is preferably 1 to 200 minutes or 5 to 100 minutes.
　重合により含水ゲル（含水ゲル状の架橋重合体）が得られた後、すぐに後述の乾燥工程に供してもよく、又はある程度の時間（例えば１０分～１時間）をおいてから乾燥工程に供してもよい。含水ゲルは、乾燥工程に供されるまでの間、２５℃以上乾燥温度未満（例えば７５℃以下）の環境下に置いてもよい。 After the water-containing gel (crosslinked polymer in the form of a water-containing gel) is obtained by the polymerization, it may be immediately subjected to the drying step described later, or after a certain period of time (for example, 10 minutes to 1 hour), the drying step may be performed. You may provide it. The hydrous gel may be placed in an environment of 25 ° C. or higher and lower than the drying temperature (for example, 75 ° C. or lower) until it is subjected to the drying step.
［粗砕］
　架橋重合体は、乾燥工程の前に予め粗砕されることが好ましい。すなわち、本実施形態に係る製造方法は、架橋重合体の乾燥工程の前に、架橋重合体を粗砕する工程を含むことが好ましい。乾燥工程前に架橋重合体を粗砕することで、乾燥をより効率的に行うことができる。粗砕工程では、例えば、重合により得られた塊状の含水ゲルを粗砕することができる。 [Coarse]
The crosslinked polymer is preferably coarsely ground in advance before the drying step. That is, it is preferable that the production method according to the present embodiment includes a step of coarsely crushing the crosslinked polymer before the step of drying the crosslinked polymer. By coarsely crushing the crosslinked polymer before the drying step, drying can be performed more efficiently. In the coarse crushing step, for example, the massive hydrogel obtained by polymerization can be coarsely crushed.
　粗砕には、例えば、ニーダー（加圧式ニーダー、双腕型ニーダー等）、ミートチョッパー、カッターミル、ファーマミル等の粗砕機を用いることができる。粗砕工程では、塊状の含水ゲルを予め例えば５ｃｍ角程度に裁断しておき、裁断された含水ゲルを粗砕に供してもよい。重合工程が、ニーダー等の装置によって撹拌重合により行われる場合は、重合工程及び粗砕工程が実質的に同時に行われてもよい。 For coarse crushing, for example, a kneader (pressurized kneader, double-armed kneader, etc.), a meat chopper, a cutter mill, a pharma mill, or the like can be used. In the coarse crushing step, the lumpy hydrogel may be cut in advance into, for example, about 5 cm square, and the cut hydrogel may be subjected to coarse crushing. When the polymerization step is carried out by stirring polymerization with an apparatus such as a kneader, the polymerization step and the coarse crushing step may be carried out substantially at the same time.
　粗砕後の架橋重合体（粗砕ゲル、粗砕重合体）は、粒子状であってよく、粒子が連なったような細長い形状であってもよい。粗砕ゲルの最小辺のサイズは、例えば、０．１～１５ｍｍ程度であってよく、１．０～１０ｍｍ程度であることが好ましい。粗砕ゲルの最大辺のサイズは、０．１～２００ｍｍ程度であってよく、１．０～１５０ｍｍ程度であることが好ましい。 The crosslinked polymer (crude gel, coarsely crushed polymer) after coarse crushing may be in the form of particles, or may have an elongated shape such that particles are connected. The size of the minimum side of the coarsely crushed gel may be, for example, about 0.1 to 15 mm, preferably about 1.0 to 10 mm. The size of the maximum side of the coarsely crushed gel may be about 0.1 to 200 mm, preferably about 1.0 to 150 mm.
［乾燥工程］
　本実施形態に係る製造方法では、乾燥工程は、下記式で示される架橋重合体の含水率変化率が９１．０％以上になるように行われる。架橋重合体の乾燥工程前含水率は７０質量％以下とする。
　含水率変化率（％）＝［（乾燥工程前含水率－乾燥工程後含水率）／乾燥工程前含水率］×１００ [Drying process]
In the production method according to the present embodiment, the drying step is performed so that the rate of change in the water content of the crosslinked polymer represented by the following formula is 91.0% or more. The water content of the crosslinked polymer before the drying step shall be 70% by mass or less.
Moisture content change rate (%) = [(Moisture content before drying step-Moisture content after drying step) / Moisture content before drying step] x 100
　本明細書において含水率とは、湿潤基準の水分割合、すなわち水分を含む架橋重合体全量に対する水分量の割合（質量％）である。 In the present specification, the water content is the water content based on the wetting standard, that is, the ratio (mass%) of the water content to the total amount of the crosslinked polymer containing water.
　本実施形態に係る吸水性樹脂粒子の製造方法によれば、乾燥工程後の架橋重合体（乾燥重合体）の、乾燥装置の金属面等からの剥離性を向上させることができ、例えば外部から架橋重合体に力を与えなくても、自然落下により金属面から架橋重合体を剥離することができる。このような効果が得られる原因は明らかではないが、十分に乾燥させることによって乾燥工程後の架橋重合体の粘着性を低減するとともに、乾燥工程前の含水率も一定以下であることによって、架橋重合体を構成する単量体等の溶出分等に由来する粘性も低減することができると推察される。ただし、原因はこれらの内容に限定されない。 According to the method for producing water-absorbent resin particles according to the present embodiment, it is possible to improve the peelability of the crosslinked polymer (dry polymer) after the drying step from the metal surface of the drying device, for example, from the outside. The crosslinked polymer can be peeled off from the metal surface by natural dropping without applying force to the crosslinked polymer. The reason why such an effect is obtained is not clear, but the adhesiveness of the crosslinked polymer after the drying step is reduced by sufficient drying, and the water content before the drying step is also below a certain level, so that the crosslinked polymer is crosslinked. It is presumed that the viscosity derived from the elution of the monomers constituting the polymer can also be reduced. However, the cause is not limited to these contents.
　本明細書において乾燥とは、架橋重合体を８０℃以上の環境に置くことによって、架橋重合体に含まれる水分の少なくとも一部を除去することをいう。 As used herein, drying means removing at least a part of the water contained in the crosslinked polymer by placing the crosslinked polymer in an environment of 80 ° C. or higher.
　架橋重合体の乾燥は、架橋重合体を金属面上に載せて行われることが好ましい。金属面は、例えば金網、穴を有する金属板等であってよい。フッ素樹脂加工等の樹脂加工がなされた金属は、加工されていない元の金属よりも伝熱率が劣る傾向があるため、効率的な乾燥を行うために、乾燥装置の金属面は樹脂加工されていないことが好ましい。本実施形態に係る製造方法によれば、樹脂加工がなされていない金属を乾燥装置の金属面の少なくとも一部に用いても、乾燥装置からの架橋重合体の剥離性に優れる。 It is preferable that the crosslinked polymer is dried by placing the crosslinked polymer on a metal surface. The metal surface may be, for example, a wire mesh, a metal plate having holes, or the like. Metals that have undergone resin processing such as fluororesin processing tend to have a lower heat transfer rate than the original unprocessed metal, so the metal surface of the drying device is resin-processed for efficient drying. It is preferable not to do so. According to the production method according to the present embodiment, even if a metal that has not been resin-processed is used for at least a part of the metal surface of the drying device, the peelability of the crosslinked polymer from the drying device is excellent.
　乾燥工程における乾燥温度は、８０℃以上であり、９０℃以上、１００℃以上、１２０℃以上、１４０℃以上、１６０℃以上、１７０℃以上、１７５℃以上又は１８０℃以上であってよい。乾燥温度は、水の沸点以上の温度であってよい。乾燥温度は、２００℃以下又は１９０℃以下であってよい。なお、本明細書において乾燥温度は、乾燥装置の設定温度、又は乾燥工程における含水ゲルの暴露雰囲気温度であってもよい。乾燥工程は、常圧で行ってもよく、減圧して行ってもよい。乾燥工程の間に一時的に環境温度が所定の乾燥温度未満又は８０℃未満となることがあってもよい。 The drying temperature in the drying step is 80 ° C. or higher, and may be 90 ° C. or higher, 100 ° C. or higher, 120 ° C. or higher, 140 ° C. or higher, 160 ° C. or higher, 170 ° C. or higher, 175 ° C. or higher, or 180 ° C. or higher. The drying temperature may be a temperature equal to or higher than the boiling point of water. The drying temperature may be 200 ° C. or lower or 190 ° C. or lower. In the present specification, the drying temperature may be the set temperature of the drying device or the exposure atmosphere temperature of the hydrogel in the drying step. The drying step may be performed at normal pressure or reduced pressure. During the drying step, the environmental temperature may be temporarily below the predetermined drying temperature or below 80 ° C.
　本明細書において乾燥工程前含水率とは、架橋重合体を乾燥工程に供する直前における含水率である。乾燥工程に供する直前とは、例えば乾燥が乾燥装置を用いて行われる場合は、乾燥装置内の所定箇所に架橋重合体を設置する直前である。製造方法が架橋重合体の粗砕工程を含む場合、粗砕直後の架橋重合体の含水率を、乾燥工程前含水率としてもよい。 In the present specification, the water content before the drying step is the water content immediately before the crosslinked polymer is subjected to the drying step. Immediately before being subjected to the drying step is, for example, immediately before installing the crosslinked polymer at a predetermined place in the drying apparatus when the drying is performed using the drying apparatus. When the production method includes a rough crushing step of the crosslinked polymer, the water content of the crosslinked polymer immediately after the rough crushing may be used as the water content before the drying step.
　乾燥工程前含水率は、５５％以上であることが好ましい。乾燥工程前含水率が５５％以上であることによって、乾燥工程前後の含水率変化率を好ましい範囲内に調整しやすくなるとともに、含水ゲルの乾燥工程中の劣化を抑えることができる。乾燥工程前含水率は、６８質量％以下、６６質量％以下、６４質量％以下、６２質量％以下、又は６０質量％以下であってもよい。 The moisture content before the drying step is preferably 55% or more. When the water content before the drying step is 55% or more, the rate of change in the water content before and after the drying step can be easily adjusted within a preferable range, and deterioration of the water-containing gel during the drying step can be suppressed. The moisture content before the drying step may be 68% by mass or less, 66% by mass or less, 64% by mass or less, 62% by mass or less, or 60% by mass or less.
　乾燥工程前含水率は、例えば、架橋重合体の重合に用いる単量体水溶液の水分率を調整することにより調整することができる。単量体水溶液の水分率は、重合して得られる塊状の含水ゲルの含水率、及び粗砕後の架橋重合体の含水率に影響するからである。また、重合工程を窒素気流下で実施すること、重合工程中の反応熱でゲルが高温となり発生する蒸気を留去させること、及び／又は、重合して得られた塊状の含水ゲルを窒素気流下で粗砕工程に供することにより、乾燥工程前含水率を低減させてもよい。また、塊状の含水ゲル又は粗砕後の架橋重合体に、必要に応じて水分を添加することにより乾燥工程前含水率を増加させてもよい。 The water content before the drying step can be adjusted, for example, by adjusting the water content of the monomer aqueous solution used for the polymerization of the crosslinked polymer. This is because the water content of the monomer aqueous solution affects the water content of the massive hydrogel obtained by polymerization and the water content of the crosslinked polymer after coarse crushing. Further, the polymerization step is carried out under a nitrogen stream, the gel becomes hot due to the heat of reaction during the polymerization step and the generated vapor is distilled off, and / or the massive hydrogel obtained by the polymerization is subjected to a nitrogen stream. The water content before the drying step may be reduced by subjecting it to the coarse crushing step below. Further, the water content before the drying step may be increased by adding water as necessary to the lumpy water-containing gel or the crosslinked polymer after coarse crushing.
　架橋重合体を乾燥するための乾燥装置は、予め８０℃以上、好ましくは所定の乾燥温度に設定しておき、架橋重合体を乾燥装置内に設置すると同時に乾燥を開始することが好ましい。 It is preferable that the drying device for drying the crosslinked polymer is set to 80 ° C. or higher, preferably a predetermined drying temperature in advance, and the drying is started at the same time as the crosslinked polymer is installed in the drying device.
　乾燥工程の時間は、乾燥温度等の条件に応じて、乾燥後の含水率が適切な範囲となるよう設定すればよい。乾燥工程の時間は累計で、例えば１５分以上、２０分以上、２５分以上、又は３０分以上であってよく、１２０分以下、９０分以下、又は６０分以下であってよい。 The time of the drying step may be set so that the moisture content after drying is in an appropriate range according to the conditions such as the drying temperature. The total time of the drying step may be, for example, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and may be 120 minutes or less, 90 minutes or less, or 60 minutes or less.
　架橋重合体の乾燥は、例えば熱風乾燥機、減圧乾燥機、通気ベルト式乾燥機、通気バンド型乾燥機、回転型通気乾燥機、攪拌乾燥機、流動層乾燥機、振動流動乾燥機、減圧乾燥機等の乾燥装置を用いて行うことができる。 Drying of the crosslinked polymer is performed, for example, by hot air dryer, vacuum dryer, ventilation belt type dryer, ventilation band type dryer, rotary ventilation dryer, stirring dryer, fluidized layer dryer, vibration fluid dryer, vacuum drying. This can be done using a drying device such as a machine.
　本明細書において乾燥工程後含水率とは、架橋重合体の乾燥工程を終了した直後における含水率である。乾燥工程を終了した直後とは、例えば乾燥装置を用いて乾燥を行う場合には、架橋重合体を乾燥装置から取り出した直後である。例えば複数の乾燥装置を用いる場合は、最後に用いられる乾燥装置から取り出した直後である。乾燥工程後に架橋重合体の粉砕を行う場合は、例えば、粉砕直前の架橋重合体の含水率を乾燥工程後含水率としてもよい。ただし乾燥工程後であって粉砕工程前に、架橋重合体に添加剤水溶液を加えるなどにより架橋重合体に水分を加える場合は、水分を加える前の架橋重合体の含水率を、乾燥工程後含水率とする。 In the present specification, the water content after the drying step is the water content immediately after the drying step of the crosslinked polymer is completed. Immediately after the completion of the drying step is, for example, immediately after the crosslinked polymer is taken out from the drying device when drying using a drying device. For example, when a plurality of drying devices are used, it is immediately after being taken out from the last used drying device. When the crosslinked polymer is pulverized after the drying step, for example, the water content of the crosslinked polymer immediately before pulverization may be used as the water content after the drying step. However, when water is added to the crosslinked polymer by adding an additive aqueous solution to the crosslinked polymer after the drying step and before the pulverization step, the water content of the crosslinked polymer before the addition of water is determined by the water content after the drying step. Let it be a rate.
　乾燥工程後含水率は、乾燥工程後の架橋重合体の粉砕をより効率的に行う観点、及び得られる吸水性樹脂粒子の性能のバランスを向上させる観点から、１０質量％以下であることが好ましい。乾燥工程後含水率は、８質量％以下、又は６質量％以下であってもよく、０．５質量％以上、１質量％以上、１．５質量％以上又は２質量％以上であってもよい。乾燥工程後含水率は、例えば、乾燥温度を高める、乾燥時間を延ばすこと等により、低減することができる。 The water content after the drying step is preferably 10% by mass or less from the viewpoint of more efficiently pulverizing the crosslinked polymer after the drying step and from the viewpoint of improving the balance of the performance of the obtained water-absorbent resin particles. .. The moisture content after the drying step may be 8% by mass or less, 6% by mass or less, 0.5% by mass or more, 1% by mass or more, 1.5% by mass or more, or 2% by mass or more. good. The moisture content after the drying step can be reduced, for example, by increasing the drying temperature, extending the drying time, or the like.
　乾燥工程前後の含水率変化率は、９１．０％以上である。含水率変化率は、１００％未満であることが好ましい。乾燥工程前後の含水率変化率が１００％である場合とは、乾燥工程後に完全に水分が除去され、乾燥工程後の含水率が０質量％である場合である。乾燥工程後の含水率変化率は、９９．０％以下、９８．０％以下、９７．０％以下、９６．０％以下、又は９５．０％以下であってもよい。 The rate of change in water content before and after the drying process is 91.0% or more. The water content change rate is preferably less than 100%. The case where the water content change rate before and after the drying step is 100% is the case where the water content is completely removed after the drying step and the water content after the drying step is 0% by mass. The rate of change in water content after the drying step may be 99.0% or less, 98.0% or less, 97.0% or less, 96.0% or less, or 95.0% or less.
　乾燥工程前後の含水率変化率を９１．０％以上に調整するために、例えば、単量体水溶液の水分率、単量体水溶液の固形分量、乾燥温度、乾燥時間等を調整することができる。 In order to adjust the water content change rate before and after the drying step to 91.0% or more, for example, the water content of the monomer aqueous solution, the solid content of the monomer aqueous solution, the drying temperature, the drying time and the like can be adjusted. ..
［剥離］
　乾燥工程後、乾燥された架橋重合体を乾燥装置から取り出すことができる。乾燥工程の間に架橋重合体が金属面に載置されている場合、架橋重合体は該金属面から剥離される。本実施形態に係る製造方法によれば、外部から力を加えなくても、例えば自然落下により架橋重合体を乾燥装置の金属面から剥離することができる。 [Peeling]
After the drying step, the dried crosslinked polymer can be taken out from the drying apparatus. If the crosslinked polymer is placed on a metal surface during the drying step, the crosslinked polymer is stripped from the metal surface. According to the production method according to the present embodiment, the crosslinked polymer can be peeled off from the metal surface of the drying apparatus by, for example, free fall, without applying an external force.
［粉砕］
　粗砕及び乾燥工程後の架橋重合体（粗砕乾燥重合体）は、更に粉砕されることが好ましい。すなわち本実施形態に係る製造方法は、乾燥工程後に架橋重合体の粉砕工程を含むことが好ましい。粉砕によって、更に小さい粒子径を有する粒子状の架橋重合体（重合体粒子）を得ることができる。 [Crush]
The crosslinked polymer (coarsely crushed and dried polymer) after the coarse crushing and drying steps is preferably further pulverized. That is, the production method according to the present embodiment preferably includes a step of pulverizing the crosslinked polymer after the drying step. By pulverization, a particulate crosslinked polymer (polymer particles) having a smaller particle size can be obtained.
　粉砕には、例えば、ローラーミル（ロールミル）、スタンプミル、ジェットミル、高速回転粉砕機（ハンマーミル、ピンミル、ロータビータミル等）、容器駆動型ミル（回転ミル、振動ミル、遊星ミル等）等の粉砕機を使用することができる。好ましくは、高速回転粉砕機が使用される。粉砕機は、出口側に多孔板やスクリーン、グリッド等の、粉砕粒子の最大粒子径を制御する開口部を有していてもよい。開口部の形状は多角形、円形等であってよく、開口部の最大径は０．１～５ｍｍ、０．３～３．０ｍｍ、又は０．５～１．５ｍｍであってよい。 For crushing, for example, roller mill (roll mill), stamp mill, jet mill, high-speed rotary crusher (hammer mill, pin mill, rotor beater mill, etc.), container-driven mill (rotary mill, vibration mill, planetary mill, etc.), etc. You can use the crusher. Preferably, a high speed rotary grinder is used. The crusher may have an opening on the outlet side, such as a perforated plate, a screen, or a grid, for controlling the maximum particle size of the crushed particles. The shape of the opening may be polygonal, circular, or the like, and the maximum diameter of the opening may be 0.1 to 5 mm, 0.3 to 3.0 mm, or 0.5 to 1.5 mm.
［分級、粒度調整］
　粉砕して得られた粒子状の架橋重合体を更に分級してもよい。本実施形態に係る製造方法は、粉砕後の架橋重合体を分級する工程を含んでもよい。分級とは、ある粒子群を、粒径に応じて、２つ又はそれ以上の数の、粒度分布の異なる粒子群に分ける操作のことをいう。また、分級後の粒子を再度粉砕して、粉砕工程と分級工程とを繰り返すなど、複数の分級工程を行ってもよく、後述する表面架橋工程後に分級工程を行ってもよい。粒子の分級は、例えば、スクリーン分級、風力分級等の方法によって行うことができる。粒子は、必要に応じて造粒が行われてもよい。分級により得られた各粒度の架橋重合体を、必要に応じて再度混合することによって、所望の粒度分布を有するように粒度調整を行ってもよい。 [Classification, particle size adjustment]
The particulate crosslinked polymer obtained by pulverization may be further classified. The production method according to the present embodiment may include a step of classifying the crosslinked polymer after pulverization. Classification refers to an operation of dividing a certain particle group into two or more particle groups having different particle size distributions according to the particle size. Further, a plurality of classification steps may be performed, such as crushing the classified particles again and repeating the crushing step and the classification step, or the classification step may be performed after the surface cross-linking step described later. The particle classification can be performed by, for example, a screen classification, a wind power classification, or the like. The particles may be granulated as needed. The particle size may be adjusted so as to have a desired particle size distribution by remixing the crosslinked polymer of each particle size obtained by the classification, if necessary.
［表面架橋］
　本実施形態に係る吸水性樹脂粒子の製造方法は、重合体粒子の表面架橋を行う工程を含んでもよい。表面架橋は、例えば、表面架橋を行うための架橋剤（表面架橋剤）を重合体粒子に対して添加して反応させることにより行うことができる。 [Surface cross-linking]
The method for producing water-absorbent resin particles according to the present embodiment may include a step of performing surface cross-linking of the polymer particles. Surface cross-linking can be performed, for example, by adding a cross-linking agent (surface cross-linking agent) for performing surface cross-linking to the polymer particles and reacting them.
　表面架橋剤は、例えば、エチレン性不飽和単量体由来の官能基との反応性を有する官能基（反応性官能基）を２個以上含有するものであってよい。表面架橋剤としては、例えば、エチレングリコール、プロピレングリコール、１，４－ブタンジオール、トリメチロールプロパン、グリセリン、ポリオキシエチレングリコール、ポリオキシプロピレングリコール、ポリグリセリン等のポリオール類；（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）グリセリンジグリシジルエーテル、（ポリ）グリセリントリグリシジルエーテル、（ポリ）プロピレングリコールポリグリシジルエーテル、（ポリ）グリセロールポリグリシジルエーテル等のポリグリシジル化合物；エピクロルヒドリン、エピブロムヒドリン、α－メチルエピクロルヒドリン等のハロエポキシ化合物；２，４－トリレンジイソシアネート、ヘキサメチレンジイソシアネート等のイソシアネート化合物等の反応性官能基を２個以上有する化合物；３－メチル－３－オキセタンメタノール、３－エチル－３－オキセタンメタノール、３－ブチル－３－オキセタンメタノール、３－メチル－３－オキセタンエタノール、３－エチル－３－オキセタンエタノール、３－ブチル－３－オキセタンエタノール等のオキセタン化合物；１，２－エチレンビスオキサゾリン等のオキサゾリン化合物；エチレンカーボネート等のカーボネート化合物；ビス［Ｎ，Ｎ－ジ（β－ヒドロキシエチル）］アジプアミド等のヒドロキシアルキルアミド化合物等が挙げられる。 The surface cross-linking agent may contain, for example, two or more functional groups (reactive functional groups) having reactivity with a functional group derived from an ethylenically unsaturated monomer. Examples of the surface cross-linking agent include polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene glycol di. Polyglycidyl compounds such as glycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, (poly) glycerol polyglycidyl ether; epichlorohydrin, epibromhydrin, α- Haloepoxy compounds such as methylepicrolhydrin; compounds having two or more reactive functional groups such as isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; 3-methyl-3-oxetanemethanol, 3-ethyl-3- Oxetane compounds such as oxetane methanol, 3-butyl-3-oxetane methanol, 3-methyl-3-oxetane ethanol, 3-ethyl-3-oxetan ethanol, 3-butyl-3-oxetane ethanol; 1,2-ethylenebisoxazoline Oxazoline compounds such as; carbonate compounds such as ethylene carbonate; hydroxyalkylamide compounds such as bis [N, N-di (β-hydroxyethyl)] adipamide and the like can be mentioned.
［吸水性樹脂粒子］
　本実施形態に係る製造方法により得られる吸水性樹脂粒子は、上述の粒子状の架橋重合体（重合体粒子）を含む。吸水性樹脂粒子は、重合体粒子のみからなるものであってもよく、例えば、ゲル安定剤、金属キレート剤（エチレンジアミン４酢酸及びその塩、ジエチレントリアミン５酢酸及びその塩、例えばジエチレントリアミン５酢酸５ナトリウム等）、流動性向上剤（滑剤）等の追加成分を更に含んでもよい。追加成分は、重合体粒子の内部、表面上又はこれらの両方に配置され得る。 [Water-absorbent resin particles]
The water-absorbent resin particles obtained by the production method according to the present embodiment include the above-mentioned particulate crosslinked polymer (polymer particles). The water-absorbent resin particles may be composed of only polymer particles, and may be, for example, a gel stabilizer, a metal chelating agent (ethylenediamine 4 acetic acid and its salt, diethylenetriamine 5 acetic acid and its salt, for example, diethylenetriamine 5 acetate 5 sodium and the like, etc. ), An additional component such as a fluidity improver (lubricant) may be further contained. Additional components may be placed inside, on the surface, or both of the polymer particles.
　吸水性樹脂粒子は、重合体粒子の表面上に配置された複数の無機粒子を含んでいてもよい。本実施形態に係る製造方法は、重合体粒子の表面に無機粒子を付着させる工程を更に含んでもよい。 The water-absorbent resin particles may contain a plurality of inorganic particles arranged on the surface of the polymer particles. The production method according to the present embodiment may further include a step of adhering the inorganic particles to the surface of the polymer particles.
　本実施形態に係る製造方法により得られる吸水性樹脂粒子の形状は、例えば、破砕状、又は破砕状粒子が凝集して形成された形状であってよい。吸水性樹脂粒子の中位粒子径は、１３０～８００μｍ、２００～８５０μｍ、２５０～７００μｍ、３００～６００μｍ又は３００～４５０μｍであってよい。 The shape of the water-absorbent resin particles obtained by the production method according to the present embodiment may be, for example, a crushed shape or a shape formed by aggregating crushed particles. The medium particle size of the water-absorbent resin particles may be 130 to 800 μm, 200 to 850 μm, 250 to 700 μm, 300 to 600 μm, or 300 to 450 μm.
　本実施形態に係る製造方法により得られる吸水性樹脂粒子は、吸水性に優れ、例えば、紙おむつ、生理用品等の衛生材料、保水剤、土壌改良剤等の農園芸材料、止水剤、結露防止剤等の工業資材などの分野において用いることができる。 The water-absorbent resin particles obtained by the production method according to the present embodiment have excellent water absorption, and are, for example, sanitary materials such as disposable diapers and sanitary products, agricultural and horticultural materials such as water-retaining agents and soil conditioners, water-stopping agents, and dew condensation prevention. It can be used in fields such as industrial materials such as agents.
　以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。 The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
＜製造例１＞
［単量体水溶液の調製］
　２Ｌのセパラブルフラスコに３３９．３９ｇ（４．７１モル）のアクリル酸を入れた。セパラブルフラスコ内のアクリル酸に、撹拌しながらイオン交換水２９２．３０ｇを加えた。次いで、約３℃の氷水浴下で２９７．４５ｇの４８質量％水酸化ナトリウム水溶液を滴下することにより、単量体濃度４５．０質量％のアクリル酸の部分中和液（中和率７５．８モル％）を調製した。 <Manufacturing example 1>
[Preparation of aqueous monomer solution]
339.39 g (4.71 mol) of acrylic acid was placed in a 2 L separable flask. To the acrylic acid in the separable flask, 292.30 g of ion-exchanged water was added with stirring. Then, by dropping 297.45 g of a 48 mass% sodium hydroxide aqueous solution under an ice water bath at about 3 ° C., a partial neutralizing solution of acrylic acid having a monomer concentration of 45.0 mass% (neutralization rate 75. 8 mol%) was prepared.
［粗砕ゲルの作製］
（重合工程）
　上記アクリル酸部分中和液８８９．２８ｇ、イオン交換水１４３．４０ｇ、内部架橋剤としてポリエチレングリコールジアクリレート（ｎ≒９）０．４１２ｇ（日油株式会社、ブレンマーＡＤＥ－４００Ａ）、及び濃度２質量％の過硫酸カリウム水溶液１６．１４ｇを、フッ素樹脂コーティングされた１８－８ステンレスバット（外寸：２９７ｍｍ×２３２ｍｍ×高さ５０ｍｍ）内に入れ、２個の撹拌子（直径８ｍｍ、長さ４５ｍｍ）で撹拌することにより、ステンレスバット内に均一な混合物を形成させた。その後、ステンレスバットの上部をポリエチレンフィルムでカバーした。ステンレスバッド内の混合物の温度を２５℃に調整後、内径３ｍｍのフッ素樹脂製の窒素導入管（流量２００ｍｌ／分）を差し込み、バット内の混合物を窒素置換することにより、溶存酸素量を０．１ｐｐｍ以下に調整した。次いで、混合物を３００ｒｐｍで撹拌しながら、注射器（テルモ株式会社製１０ｍＬ容ディスポシリンジ、テルモ株式会社製注射針）を用いて０．５質量％のＬ－アスコルビン酸水溶液３．３９ｇを滴下した。 [Preparation of coarsely crushed gel]
(Polymerization process)
889.28 g of the above acrylic acid partial neutralizing solution, 143.40 g of ion-exchanged water, 0.412 g of polyethylene glycol diacrylate (n≈9) as an internal cross-linking agent (Nichiyu Co., Ltd., Blemmer ADE-400A), and a concentration of 2 mass. A. By stirring with, a uniform mixture was formed in the stainless steel bat. After that, the upper part of the stainless steel vat was covered with a polyethylene film. After adjusting the temperature of the mixture in the stainless steel pad to 25 ° C, insert a fluororesin nitrogen introduction tube (flow rate 200 ml / min) with an inner diameter of 3 mm and replace the mixture in the bat with nitrogen to reduce the amount of dissolved oxygen to 0. It was adjusted to 1 ppm or less. Then, while stirring the mixture at 300 rpm, 3.39 g of a 0.5 mass% L-ascorbic acid aqueous solution was added dropwise using a syringe (10 mL disposable syringe manufactured by Terumo Corporation, injection needle manufactured by Terumo Corporation).
　Ｌ－アスコルビン酸水溶液を滴下後、１分後に重合反応が開始した。重合反応の進行に伴って反応液の粘度が増加していった後、反応液がゲル化した。Ｌ－アスコルビン酸水溶液を滴下終了後１２分の時点で、設置した温度計は８８．３℃を示し、その後温度が低下し始めた。 After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. Twelve minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 88.3 ° C., and then the temperature began to decrease.
　反応液のゲル化によって形成された含水ゲル（含水ゲル状の架橋重合体）が入ったステンレスバットを７５℃の水浴に浸し、その状態で含水ゲルを２０分間加温して重合反応を充分完了させた。 A stainless steel vat containing a hydrogel (crosslinked polymer in the form of a hydrogel) formed by gelation of the reaction solution is immersed in a water bath at 75 ° C., and the hydrogel is heated for 20 minutes in that state to fully complete the polymerization reaction. I let you.
（粗砕工程）
　重合工程後の含水ゲルの全量を容器から取り出し、長辺を５ｃｍ間隔に切れ目を入れて裁断した。裁断した含水ゲルを喜連ローヤル株式会社製のミートチョッパー１２ＶＲ－７５０ＳＤＸに順次投入して粗砕（細分化）し、粗砕ゲルを得た。ミートチョッパーの出口に位置するプレートの穴の径は６．４ｍｍであった。この時の粗砕ゲルの含水率（乾燥工程前含水率Ａ）は５８．２％であった。 (Rough crushing process)
The entire amount of the hydrogel after the polymerization step was taken out from the container, and the long sides were cut at intervals of 5 cm and cut. The cut hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and coarsely crushed (subdivided) to obtain a coarsely crushed gel. The diameter of the hole in the plate located at the outlet of the meat chopper was 6.4 mm. The water content of the coarsely crushed gel at this time (water content A before the drying step) was 58.2%.
＜製造例２＞
　製造例１と同様の重合工程を行った。Ｌ－アスコルビン酸水溶液を滴下後、１分後に重合反応が開始した。重合反応の進行に伴って反応液の粘度が増加していった後、反応液がゲル化した。Ｌ－アスコルビン酸水溶液を滴下終了後１２分の時点で、設置した温度計は８５．９℃を示し、その後温度が低下し始めた。 <Manufacturing example 2>
The same polymerization step as in Production Example 1 was carried out. After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. Twelve minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 85.9 ° C., and then the temperature began to decrease.
　その後、工程中にポリエチレンフィルムでシールされたステンレスバット内に内径３ｍｍのフッ素樹脂製の窒素導入管（５００ｍｌ／分）を用いて窒素を通気したこと以外は、製造例１と同様に重合工程及び粗砕工程を実施した。粗砕工程後に得られた粗砕ゲルの含水率（乾燥工程前含水率Ａ）は５７．９％であった。 After that, the polymerization step and the same as in Production Example 1 except that nitrogen was aerated in a stainless steel bat sealed with a polyethylene film during the step using a fluororesin nitrogen introduction tube (500 ml / min) having an inner diameter of 3 mm. A coarse crushing step was carried out. The water content of the coarsely crushed gel obtained after the coarse crushing step (water content A before the drying step) was 57.9%.
＜製造例３＞
　製造例１と同様の重合工程を行った。Ｌ－アスコルビン酸水溶液を滴下後、１分後に重合反応が開始した。重合反応の進行に伴って反応液の粘度が増加していった後、反応液がゲル化した。Ｌ－アスコルビン酸水溶液を滴下終了後１５分の時点で、設置した温度計は８０．９℃を示し、その後温度が低下し始めた。 <Manufacturing example 3>
The same polymerization step as in Production Example 1 was carried out. After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. Fifteen minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 80.9 ° C., and then the temperature began to decrease.
　その後、工程中にステンレスバットの上部にシールされたポリエチレンフィルムを外したこと以外は製造例１と同様に、重合工程及び粗砕工程を実施した。粗砕工程後に得られた粗砕ゲルの含水率（乾燥工程前含水率Ａ）は５７．２％であった。 After that, the polymerization step and the coarse crushing step were carried out in the same manner as in Production Example 1 except that the polyethylene film sealed on the upper part of the stainless steel vat was removed during the step. The water content of the coarsely crushed gel obtained after the coarse crushing step (water content A before the drying step) was 57.2%.
＜製造例４＞
　製造例１と同様の重合工程を行った。Ｌ－アスコルビン酸水溶液を滴下後、１分後に重合反応が開始した。重合反応の進行に伴って反応液の粘度が増加していった後、反応液がゲル化した。Ｌ－アスコルビン酸水溶液を滴下終了後１４分の時点で、設置した温度計は８１．９℃を示し、その後温度が低下し始めた。 <Manufacturing example 4>
The same polymerization step as in Production Example 1 was carried out. After dropping the L-ascorbic acid aqueous solution, the polymerization reaction started 1 minute later. After the viscosity of the reaction solution increased with the progress of the polymerization reaction, the reaction solution gelled. 14 minutes after the completion of dropping the L-ascorbic acid aqueous solution, the installed thermometer showed 81.9 ° C., and then the temperature began to decrease.
　粗砕工程後、撹拌翼としてビーターと呼ばれる撹拌翼を備えたミキサー（ケンミックスアイコーシェフＰＲＯ、型式：ＫＰＬ９０００Ｓ、株式会社愛工舎製作所）に、粗砕ゲル１６０ｇを投入し、速度ダイヤルを１の目盛りで撹拌しているところへイオン交換水７５ｇを添加して５分間混合したこと以外は製造例１と同様に、重合工程及び粗砕工程を実施した。イオン交換水混合後の粗砕ゲルの含水率（乾燥工程前含水率Ａ）は７２．２％であった。 After the crushing process, 160 g of crushed gel is put into a mixer (Kenmix Aiko Chef PRO, model: KPL9000S, Aikosha Seisakusho Co., Ltd.) equipped with a stirring blade called a beater as a stirring blade, and the speed dial is set to 1 scale. The polymerization step and the coarse crushing step were carried out in the same manner as in Production Example 1 except that 75 g of ion-exchanged water was added to the stirring place and mixed for 5 minutes. The water content of the coarsely crushed gel after mixing with ion-exchanged water (water content A before the drying step) was 72.2%.
＜実施例１＞
（乾燥工程）
　目開き１．７ｍｍのＪＩＳ篩（直径２０ｃｍ）の中央から１５ｃｍΦの範囲内に、製造例１で得られた粗砕ゲル６０ｇを均一になるように置いた。その後、粗砕ゲル上に、直径１５ｃｍの金属シャーレ（１６７ｇ）を置き、更にシャーレ上に２５０ｇの重りを置き、粗砕ゲル上の全面へ均一な荷重をかけることにより、粗砕ゲルをＪＩＳ篩へ１０秒間押し付けた。その後、金属シャーレ及び重りを外し、予め１８０℃に設定した熱風乾燥機（ＡＤＶＡＮＴＥＣ社製、ＦＶ－３２０）内に、上記の粗砕ゲルを載せたＪＩＳ篩を入れ、２８分間乾燥工程を行うことにより、粗砕乾燥重合体を得た。乾燥工程後に乾燥機から粗砕乾燥重合体を載せたＪＩＳ篩を取り出した後、速やかに後述の剥離率試験を実施した。 <Example 1>
(Drying process)
60 g of the coarsely crushed gel obtained in Production Example 1 was placed uniformly within a range of 15 cmΦ from the center of a JIS sieve (diameter 20 cm) having an opening of 1.7 mm. Then, a metal petri dish (167 g) having a diameter of 15 cm is placed on the coarsely crushed gel, a weight of 250 g is further placed on the crushed gel, and a uniform load is applied to the entire surface of the coarsely crushed gel to sieve the coarsely crushed gel. Pressed against for 10 seconds. After that, the metal petri dish and the weight are removed, and the JIS sieve on which the above-mentioned coarsely crushed gel is placed is placed in a hot air dryer (manufactured by ADVANTEC, FV-320) set in advance at 180 ° C., and the drying step is performed for 28 minutes. To obtain a coarsely crushed dry polymer. After the JIS sieve on which the coarsely crushed and dried polymer was placed was taken out from the dryer after the drying step, the peeling rate test described later was immediately carried out.
　表１に示す製造例番号により得られた粗砕ゲルを用い、乾燥時間及び乾燥温度を表１に示すとおりに変更したこと以外は実施例１と同様にして、実施例２～５及び比較例１～１０の製造方法を行った。 Examples 2 to 5 and Comparative Examples were the same as in Example 1 except that the drying time and the drying temperature were changed as shown in Table 1 using the coarsely crushed gel obtained by the production example numbers shown in Table 1. The manufacturing method of 1 to 10 was performed.
［含水率測定］
　測定試料の乾燥工程前含水率Ａ及び乾燥工程後含水率Ｂを以下の方法で測定した。なお、乾燥工程前含水率Ａの測定には、粗砕工程で得られた粗砕ゲル（製造例４ではイオン交換水混合後の粗砕ゲル）２０．０ｇをサンプリングしたものを測定試料として用いた。また、乾燥工程後含水率Ｂの測定には、乾燥工程（１８０℃、所定時間）の直後に得られた粗砕乾燥重合体２０．０ｇをサンプリングしたものを測定試料として用いた。 [Measurement of water content]
The water content A before the drying step and the water content B after the drying step of the measurement sample were measured by the following methods. For the measurement of the water content A before the drying step, a sample of 20.0 g of the coarsely crushed gel obtained in the rough crushing step (in Production Example 4, the coarsely crushed gel after mixing with ion-exchanged water) is used as a measurement sample. board. For the measurement of the water content B after the drying step, a sample of 20.0 g of the coarsely crushed dried polymer obtained immediately after the drying step (180 ° C., predetermined time) was used as a measurement sample.
　予め恒量（Ｗ１（ｇ））としたフッ素樹脂コーティングされたステンレスバット（外寸：１８５ｍｍ×１４０ｍｍ×高さ３０ｍｍ）に上記測定試料をとり、ステンレスバット及び測定試料の合計質量Ｗ２（ｇ）を精秤した。精秤された測定試料を、上述のステンレスバットに載せたまま内温を２００℃に設定した熱風乾燥機（ＡＤＶＡＮＴＥＣ社製、型式：ＦＶ－３２０）で２時間乾燥させた。乾燥後の測定試料をデシケーター中で放冷した後、ステンレスバット及び測定試料の合計質量Ｗ３（ｇ）を精秤した。以下の式から、測定試料の含水率を算出した。
含水率（質量％）＝［｛（Ｗ２－Ｗ１）－（Ｗ３－Ｗ１）｝／（Ｗ２－Ｗ１）］×１００ The above measurement sample is placed on a fluororesin-coated stainless steel vat (outer dimensions: 185 mm × 140 mm × height 30 mm) that has been preliminarily set to a constant amount (W1 (g)), and the total mass W2 (g) of the stainless steel vat and the measurement sample is refined. Weighed. The finely weighed measurement sample was dried for 2 hours in a hot air dryer (manufactured by ADVANTEC, model: FV-320) in which the internal temperature was set to 200 ° C. while being placed on the above-mentioned stainless steel vat. After allowing the dried measurement sample to cool in a desiccator, the total mass W3 (g) of the stainless bat and the measurement sample was precisely weighed. The water content of the measurement sample was calculated from the following formula.
Moisture content (% by mass) = [{(W2-W1)-(W3-W1)} / (W2-W1)] × 100
　乾燥工程前含水率Ａ及び乾燥工程後含水率Ｂを用いて、以下の式により乾燥工程前後の含水率変化量（質量％）を算出した。
　乾燥工程前後の含水率変化量（質量％）＝乾燥工程前含水率Ａ－乾燥工程後含水率Ｂ Using the water content A before the drying step and the water content B after the drying step, the amount of change in the water content (mass%) before and after the drying step was calculated by the following formula.
Moisture content change before and after the drying step (mass%) = Moisture content before the drying step A-Moisture content after the drying step B
　さらに、乾燥工程前後の含水率変化量から、以下の式により乾燥工程前後の含水率変化率（％）を算出した。
　乾燥工程前後の含水率変化率（％）＝（乾燥工程前後の含水率変化量／乾燥工程前含水率Ａ）×１００ Further, from the amount of change in water content before and after the drying step, the rate of change in water content (%) before and after the drying step was calculated by the following formula.
Moisture content change rate before and after the drying step (%) = (Moisture content change before and after the drying step / Moisture content before the drying step A) x 100
［剥離率試験］
　乾燥工程後、粗砕乾燥重合体が載ったＪＩＳ篩を、ＪＩＳ篩の網面が地面に対して平行であるように保ちながら振動を与えないように、熱風乾燥機内から取り出した。取り出し終わってから５秒以内（その間、ＪＩＳ篩へ振動を与えないように、かつＪＩＳ篩の網面が地面に対して平行であるように保ちながら）に、ＪＩＳ篩を３秒かけて１８０°上下反対に返し、その時にＪＩＳ篩から落下した粗砕乾燥重合体をバット内に回収した。落下した粗砕乾燥重合体の重量Ｗ４（ｇ）、及びＪＩＳ篩上に付着したまま残った粗砕乾燥重合体の重量Ｗ５（ｇ）を測定した。剥離率は以下の式により算出した。結果を表１に示す。
　剥離率（質量％）＝［Ｗ４/（Ｗ４＋Ｗ５）］×１００ [Peeling rate test]
After the drying step, the JIS sieve on which the coarsely crushed and dried polymer was placed was taken out from the inside of the hot air dryer so as not to give vibration while keeping the mesh surface of the JIS sieve parallel to the ground. Within 5 seconds after the removal is completed (while keeping the JIS sieve from vibrating and keeping the mesh surface of the JIS sieve parallel to the ground), the JIS sieve is placed at 180 ° over 3 seconds. It was turned upside down, and the coarsely crushed dry polymer dropped from the JIS sieve at that time was recovered in a bat. The weight W4 (g) of the dropped coarsely crushed dry polymer and the weight W5 (g) of the coarsely crushed and dried polymer remaining adhered to the JIS sieve were measured. The peeling rate was calculated by the following formula. The results are shown in Table 1.
Peeling rate (mass%) = [W4 / (W4 + W5)] x 100
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例の製造方法では、乾燥工程後の粗砕乾燥重合体の全量がＪＩＳ篩から自然落下により剥離した。一方、乾燥工程後含水率が十分に低いが乾燥工程前後の含水率変化率が９１．０％未満である比較例７では、剥離性が悪かった。また、乾燥工程前含水率が７０質量％を超える比較例９、１０では、乾燥工程前後の含水率変化率が９１．０％を超えていても剥離性が悪かった。 In the production method of the example, the entire amount of the coarsely crushed and dried polymer after the drying step was peeled off from the JIS sieve by free fall. On the other hand, in Comparative Example 7 in which the water content after the drying step was sufficiently low but the rate of change in the water content before and after the drying step was less than 91.0%, the peelability was poor. Further, in Comparative Examples 9 and 10 in which the water content before the drying step exceeded 70% by mass, the peelability was poor even if the rate of change in the water content before and after the drying step exceeded 91.0%.

Claims (5)

  1. 　架橋重合体を含む吸水性樹脂粒子の製造方法であって、
    　架橋重合体を乾燥する乾燥工程を含み、
    　前記架橋重合体の乾燥工程前含水率が７０質量％以下であり、
    　前記乾燥工程が、下記式で示される前記架橋重合体の含水率変化率が９１．０％以上になるように行われる、方法。
    　含水率変化率（％）＝［（乾燥工程前含水率－乾燥工程後含水率）／乾燥工程前含水率］×１００     A method for producing water-absorbent resin particles containing a crosslinked polymer.
    Including a drying step of drying the crosslinked polymer,
    The water content of the crosslinked polymer before the drying step is 70% by mass or less, and the crosslinked polymer has a water content of 70% by mass or less.
    A method in which the drying step is performed so that the water content change rate of the crosslinked polymer represented by the following formula is 91.0% or more.
    Moisture content change rate (%) = [(Moisture content before drying step-Moisture content after drying step) / Moisture content before drying step] x 100
  2. 　前記乾燥工程が、前記含水率変化率が９１．０％以上１００％未満となるように行われる、請求項１に記載の方法。 The method according to claim 1, wherein the drying step is performed so that the moisture content change rate is 91.0% or more and less than 100%.
  3. 　前記乾燥工程が、前記乾燥工程後含水率が１０質量％以下となるように行われる、請求項１又は２に記載の方法。 The method according to claim 1 or 2, wherein the drying step is performed so that the water content after the drying step is 10% by mass or less.
  4. 　前記乾燥工程前に、前記架橋重合体を粗砕することを更に含む、請求項１～３のいずれか一項に記載の方法。 The method according to any one of claims 1 to 3, further comprising coarsely crushing the crosslinked polymer before the drying step.
  5. 　前記乾燥工程後に、前記架橋重合体を粉砕することを更に含む、請求項１～４のいずれか一項に記載の方法。 The method according to any one of claims 1 to 4, further comprising pulverizing the crosslinked polymer after the drying step.
PCT/JP2021/026670 2020-07-28 2021-07-15 Method for producing water-absorbing resin particles WO2022024787A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2022540169A JPWO2022024787A1 (en) 2020-07-28 2021-07-15

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2020127419 2020-07-28
JP2020-127419 2020-07-28

Publications (1)

Publication Number Publication Date
WO2022024787A1 true WO2022024787A1 (en) 2022-02-03

Family

ID=80036412

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2021/026670 WO2022024787A1 (en) 2020-07-28 2021-07-15 Method for producing water-absorbing resin particles

Country Status (2)

Country Link
JP (1) JPWO2022024787A1 (en)
WO (1) WO2022024787A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017221911A1 (en) * 2016-06-20 2017-12-28 株式会社日本触媒 Method for producing water absorbent
WO2018174175A1 (en) * 2017-03-24 2018-09-27 住友精化株式会社 Method for producing water-absorbing resin
WO2019221235A1 (en) * 2018-05-16 2019-11-21 株式会社日本触媒 Method for producing water-absorbing resin
WO2019221154A1 (en) * 2018-05-16 2019-11-21 株式会社日本触媒 Method for producing water-absorbent resin particles

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017221911A1 (en) * 2016-06-20 2017-12-28 株式会社日本触媒 Method for producing water absorbent
WO2018174175A1 (en) * 2017-03-24 2018-09-27 住友精化株式会社 Method for producing water-absorbing resin
WO2019221235A1 (en) * 2018-05-16 2019-11-21 株式会社日本触媒 Method for producing water-absorbing resin
WO2019221154A1 (en) * 2018-05-16 2019-11-21 株式会社日本触媒 Method for producing water-absorbent resin particles

Also Published As

Publication number Publication date
JPWO2022024787A1 (en) 2022-02-03

Similar Documents

Publication Publication Date Title
JP4511774B2 (en) Continuous production method of cross-linked fine-grained gel-like polymer
KR101789350B1 (en) A process for the production of a superabsorbent polymer
EP2980128B1 (en) Water-absorbent resin composition production method
EP3124502B1 (en) Method for producing water-absorbent resin particle
JPWO2011111657A1 (en) Method for drying particulate hydrogel crosslinked polymer
JPWO2019221154A1 (en) Manufacturing method of water-absorbent resin particles
US9873104B2 (en) Method for producing polyacrylic acid (salt)-based water-absorbing resin
JP7355646B2 (en) Manufacturing method of water absorbent resin
JP7105586B2 (en) Method for manufacturing water absorbent resin
CN112714770B (en) Method for producing water-absorbent resin containing chelating agent
WO2022024787A1 (en) Method for producing water-absorbing resin particles
JP5528714B2 (en) Method for producing water absorbent resin
WO2022024789A1 (en) Method for producing water-absorbing resin particles
CN110167996B (en) Superabsorbent polymer and method of making the same
EP3424959B1 (en) Process for producing water-absorbing resin particles
US10450428B2 (en) Method for preparing superabsorbent polymer
WO2021049467A1 (en) Method for producing crosslinked polymer particles, and crosslinked polymer gel
WO2021049451A1 (en) Method for producing water-absorbable resin particles
WO2021235524A1 (en) Method for producing water absorbent resin particles
WO2022075289A1 (en) Method for producing water-absorbing resin particles
WO2022025122A1 (en) Method for producing water-absorbing resin particles
WO2021132026A1 (en) Method for producing water-absorbent resin particles
WO2022075256A1 (en) Method for producing water-absorbing resin particles
JP2022088113A (en) Method for producing water-absorbing resin particle
JP2022088139A (en) Method for producing water-absorbing resin particle

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21849340

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2022540169

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21849340

Country of ref document: EP

Kind code of ref document: A1