WO2020059871A1 - Procédé de production d'une résine absorbant l'eau, contenant un agent chélatant - Google Patents

Procédé de production d'une résine absorbant l'eau, contenant un agent chélatant Download PDF

Info

Publication number
WO2020059871A1
WO2020059871A1 PCT/JP2019/037091 JP2019037091W WO2020059871A1 WO 2020059871 A1 WO2020059871 A1 WO 2020059871A1 JP 2019037091 W JP2019037091 W JP 2019037091W WO 2020059871 A1 WO2020059871 A1 WO 2020059871A1
Authority
WO
WIPO (PCT)
Prior art keywords
water
polymerization
chelating agent
absorbent resin
monomer
Prior art date
Application number
PCT/JP2019/037091
Other languages
English (en)
Japanese (ja)
Inventor
加奈子 津留
智嗣 松本
好希 片田
邦彦 石▲崎▼
Original Assignee
株式会社日本触媒
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 株式会社日本触媒 filed Critical 株式会社日本触媒
Priority to KR1020217011184A priority Critical patent/KR102562511B1/ko
Priority to CN201980061281.2A priority patent/CN112714770B/zh
Priority to JP2020549156A priority patent/JP7064614B2/ja
Publication of WO2020059871A1 publication Critical patent/WO2020059871A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/04—Polymerisation in solution
    • C08F2/10—Aqueous solvent
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • 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
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
    • C08J3/075—Macromolecular gels
    • 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
    • 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
    • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
    • C08J3/245—Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/17—Amines; Quaternary ammonium compounds
    • C08K5/175—Amines; Quaternary ammonium compounds containing COOH-groups; Esters or salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/49—Phosphorus-containing compounds
    • C08K5/51—Phosphorus bound to oxygen
    • C08K5/53—Phosphorus bound to oxygen bound to oxygen and to carbon only
    • C08K5/5317—Phosphonic compounds, e.g. R—P(:O)(OR')2
    • C08K5/5333—Esters of phosphonic acids
    • C08K5/5357—Esters of phosphonic acids cyclic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C08L101/12—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity
    • C08L101/14—Compositions of unspecified macromolecular compounds characterised by physical features, e.g. anisotropy, viscosity or electrical conductivity the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels

Definitions

  • the present invention relates to a method for producing a water absorbent resin containing a chelating agent.
  • a water-absorbent resin (SAP / Super Absorbent polymer) is a water-swellable, water-insoluble polymer gelling agent, and absorbent articles such as disposable diapers and sanitary napkins, as well as agricultural and horticultural water retention agents, and industrial water stoppages. As a material, it is mainly used for disposable purposes.
  • Such a water-absorbent resin is produced through a production step such as a polymerization step, a drying step, a removal step of an undried substance if necessary, a pulverization step, a classification step, a surface cross-linking step, and the like.
  • a production step such as a polymerization step, a drying step, a removal step of an undried substance if necessary, a pulverization step, a classification step, a surface cross-linking step, and the like.
  • many functions are also required for a water absorbent resin. Specifically, the gel strength, water-soluble content, water absorption rate, water absorption capacity under pressure, liquid permeability, particle size distribution, urine resistance, antibacterial property, impact resistance (not limited to the mere water absorption capacity) Damage), powder fluidity, deodorant properties, coloring resistance (whiteness), low dust, and the like.
  • a small amount of additives may be used in the water-absorbent resin, as various additives of the water-absorbent resin, Water-soluble or water-insoluble inorganic or organic powder, surfactant, plasticizer, water-soluble polymer, water-insoluble (thermoplastic) polymer, antibacterial agent, deodorant, reducing agent, antioxidant, organic acid, inorganic acid Additives such as anti-coloring agents and chelating agents are known.
  • the water-absorbent resin in particular, polymerization stability, color tone stability of the water-absorbent resin (color stability when stored for a long time under high temperature and high humidity), urine resistance (gel) It is known to add a chelating agent (also called an ion-sequestering agent) to a water-absorbent resin for the purpose of improving deterioration prevention or the like.
  • a chelating agent also called an ion-sequestering agent
  • Patent Documents 1 to 4 disclose that a chelating agent is added to a monomer of a water-absorbing resin mainly for improving polymerization stability.
  • Patent Literatures 5 to 11 mainly describe a process for polymerizing a water-absorbent resin, a drying process, a surface cross-linking process, a granulation process, a fine powder collection process, and the like, mainly for improving urine resistance of a water-absorbent resin (preventing urine deterioration).
  • a method for producing a water-absorbing resin in which a chelating agent is added to a monomer or a polymer thereof in a production process is disclosed.
  • Patent Documents 12 to 19 and 23 disclose a method for producing a water-absorbent resin in which a metal chelating agent is added in any of the production steps in order to suppress coloring (particularly coloring with time) of the water-absorbent resin.
  • Patent Literatures 12 and 14 describe that it is known that a chelating agent is preferably present inside a water-absorbing resin for preventing coloration.
  • a method of adding a chelating agent to the inside of a water-absorbent resin by adding the chelating agent to a gel before drying discloses a water-absorbing resin composition containing a chelating agent for improving the salt resistance of the water-absorbing resin.
  • Patent Documents 21 and 23 disclose a method for producing a water-absorbent resin in which a metal chelating agent is added in any of the production steps in order to improve the urine resistance of the water-absorbent resin.
  • Patent Document 22 discloses a method for producing a water-absorbent resin in which a chelating agent is added to a second-stage monomer in a two-stage polymerization in order to improve physical properties such as a water absorption capacity under pressure of the water-absorbent resin after reverse phase suspension polymerization. Is disclosed.
  • the chelating agent used for the purpose of stabilizing polymerization in the production process and preventing drying deterioration in the above-mentioned Patent Documents 1 to 7 can also improve urine resistance when a water-absorbing resin is used if it remains in the final product. It works to prevent coloring.
  • the present inventors further studied the method for producing a water-absorbent resin containing a chelating agent, and particularly when the chelating agent is added in the polymerization step and the drying step among the above-described production steps, the addition of the chelating agent in the final product
  • a new problem has been found that it is difficult to obtain a sufficient effect commensurate with the amount.
  • the amount of the chelating agent corresponding to the amount of the chelating agent added to the monomer or the polymer gel was not contained in the water absorbent resin of the final product.
  • one embodiment of the present invention provides a chelating agent that can prevent the decomposition of the chelating agent in the process of manufacturing the water-absorbent resin and can improve the residual ratio of the chelating agent in the water-absorbent resin as a final product. It is a main object to provide a method for producing a water-absorbent resin containing the same.
  • Another object of one embodiment of the present invention is to provide a water-absorbent resin containing a chelating agent obtained by the above-described production method, which has good coloring resistance (whiteness).
  • the present inventors have investigated the cause thereof in order to solve the above-described problem that has been found this time, and found that in a step of drying a hydrogel polymer obtained by polymerizing a monomer, a step before the drying step was performed. It was found that the chelating agent that had been added to the sample was specifically reduced in the drying step. The inventors have found that the cause of the decrease in the chelating agent in the drying step is a polymerization initiator (particularly, persulfate) remaining in the hydrogel polymer.
  • the present invention controls the persulfate in the polymerization initiator at the time of polymerization or before drying (0.04 mol% or less), and further controls the gel particle size and drying conditions before drying. And suppressing the decomposition of the chelating agent in the drying step, and includes the inventions described in the following [1] to [20].
  • CRC water absorption capacity
  • the persulfate used in the polymerization step is 0 to 0.04 mol% (based on the monomer at the time of polymerization) (provided that the persulfate is 0 mol%).
  • a chelating agent is added to the monomer aqueous solution or the hydrogel polymer in a step prior to the drying step in a total of 10 ppm or more (relative to the polymerization time).
  • Monomer or solid content of hydrogel polymer) Including a chelating agent, the weight-average particle diameter (D50) of the hydrated hydrogel polymer is 1 mm or less, and in the drying step, the drying time until the solid content is 80% by weight or more is 20 minutes or less.
  • D50 weight-average particle diameter
  • the chelating agent is 10 ppm or more (based on the solid content of the hydrogel polymer) and the persulfate is 0 to 0.04 mol% (based on the polymerization time).
  • a chelating agent by drying a particulate hydrogel polymer having a weight-average particle diameter (D50) of 1 mm or less containing a monomer) until the solid content becomes 80% by weight or more for a drying time of 20 minutes or less.
  • D50 weight-average particle diameter
  • the drying time refers to a time until the solid content becomes 80% by weight or more.
  • the total amount of the chelating agent added in the steps before the drying step is 60 ppm to 1% (based on the solid content of the monomer at the time of polymerization or the solid content of the hydrogel polymer).
  • the monomer used in the polymerization step contains acrylic acid (salt), and the content of the acrylic acid (salt) is based on the total monomers (excluding the internal crosslinking agent) used in the polymerization step.
  • the water-absorbing resin containing 50 to 100 mol% of the chelating agent has a residual amount (C1) of the chelating agent of 10 ppm or more, an L value of an initial color tone of 85 or more, and a YI value of 13 or less.
  • the production method according to any one of [1] to [13], which is a polyacrylic acid (salt) -based water-absorbent resin.
  • the water-absorbent resin containing a chelating agent has a residual amount (C1) of the chelating agent of 200 ppm or more, an L value of an initial color tone of 89 or more, and a YI value of 10 or less.
  • C1 residual amount of the chelating agent of 200 ppm or more
  • L value of an initial color tone of 89 or more an L value of an initial color tone of 89 or more
  • YI value 10 or less.
  • a polyacrylic acid (salt) -based water-absorbent resin having a chelating agent content (C2) of 200 ppm or more, an initial color tone L value of 89 or more, and a YI value of 10 or less.
  • Acrylic acid (salt) is 50 to 100 mol% of the total monomer (excluding the internal cross-linking agent), 0.001 to 5 mol% of the internal cross-linking agent based on the monomer, and persulfate
  • a hydrogel polymer obtained by polymerizing an aqueous monomer solution containing a monomer and a polymerization initiator is gel-pulverized during and / or after polymerization, if necessary, to obtain a particulate hydrous polymer.
  • the water-absorbent resin according to any one of [16] to [18], wherein a monomer at the time or a solid content of the hydrogel polymer is added.
  • the decomposition of the chelating agent in the production process of the water-absorbing resin is prevented, the residual ratio of the chelating agent in the water-absorbing resin as the final product is improved, and the surface and the inside of the particles of the water-absorbing resin are improved. This has the effect that a chelating agent can be added.
  • Water absorbent resin The “water-absorbent resin” in the present invention means a water-swellable, water-insoluble polymer gelling agent.
  • water swelling means that the CRC (absorption capacity under no pressure) specified by ERT442.2-02 is 5 [g / g] or more
  • water insoluble means ERT470.2 It means that the Ext (water-soluble content) defined by ⁇ 02 is 0 to 50% by weight.
  • the water-absorbent resin can be appropriately designed according to its use, and is not particularly limited, but is preferably a hydrophilic polymer obtained by polymerizing an unsaturated monomer having a carboxyl group.
  • the composition is not limited to a form in which the total amount (100% by weight) is a polymer, and may be a composition containing a surface-crosslinked resin, an additive, or the like as long as the above performance is maintained. According to the production method of the present invention, a particulate or powdery water-absorbent resin can be produced as a final product.
  • water-absorbent resin refers to a water-absorbent resin before surface treatment or surface cross-linking, a water-absorbent resin after surface treatment or surface cross-linking, and a water absorbing resin having different shapes obtained in each step.
  • Water-absorbent resin compositions containing additives such as a water-soluble resin (for example, sheet-like, fibrous, film-like, and gel-like shapes).
  • the “polyacrylic acid (salt)” in the present invention includes acrylic acid and / or a salt thereof (hereinafter, sometimes referred to as acrylic acid (salt)) as a main component as a repeating unit, optionally including a graft component.
  • Acrylic acid (salt) is essentially 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 90 to 100 mol%. It refers to a polymer containing 100 mol%, particularly preferably substantially 100 mol%.
  • a water-soluble salt is essential, a monovalent salt is preferable as a main component of the neutralized salt, an alkali metal salt or an ammonium salt is more preferable, and an alkali metal salt is further preferable.
  • the sodium salt is particularly preferred.
  • EDANA European Disposables and Nonwovens Assoiations
  • ERT is an abbreviation of EDANA Recommended Test Metods, a method of measuring water-absorbent resin which is a European standard (almost a global standard). is there. In the present invention, the measurement is performed based on the original ERT (publicly known document: revised in 2002) unless otherwise specified.
  • CRC is an abbreviation of Centrifuge Retention Capacity (centrifuge retention capacity), and means a non-pressurized water absorption capacity (hereinafter sometimes referred to as “water absorption capacity”). Specifically, 0.200 g of the water-absorbent resin in the non-woven fabric bag was freely swelled in a large excess of 0.9% by weight aqueous sodium chloride solution for 30 minutes, and then drained with a centrifuge. Magnification (unit: [g / g]). The CRC of the hydrogel polymer (hereinafter referred to as “gel CRC”) was measured by changing the sample to 0.4 g and the free swelling time to 24 hours.
  • AAP is an abbreviation for Absorption against Pressure, and means the water absorption capacity under pressure. Specifically, 0.900 g of a water-absorbing resin is swollen against a 0.9% by weight aqueous solution of sodium chloride for 1 hour under a load of 2.06 kPa (0.3 psi, 21 [g / cm 2 ]). It is a water absorption capacity (unit: [g / g]) after the water absorption.
  • the measurement may be performed with the load condition changed to 4.83 kPa (0.7 psi, 49 [g / cm 2 ]). In this case, AAP (0.7 psi) is used. Describe.
  • Ext is an abbreviation for Extractables and means a water-soluble component (amount of water-soluble component). Specifically, it is the amount of dissolved polymer (unit: wt%) after adding 1.000 g of the water-absorbing resin to 200 ml of 0.9 wt% aqueous sodium chloride solution and stirring for 16 hours. The measurement of the amount of the dissolved polymer is performed using pH titration. The water-soluble content of the hydrogel polymer (hereinafter, referred to as “gel Ext”) was measured by changing the sample to 5.0 g and the stirring time to 24 hours.
  • PSD is an abbreviation of Particle Size Distribution, and means a particle size distribution measured by sieve classification.
  • the weight average particle diameter (D50) and the particle diameter distribution width are described in “(3) Mass-Average Particle Diameter (D50) and Logarithmic Standard Deviation ( ⁇ ) of Particle Diameter Distribution” described in US Pat. No. 7,638,570. Measure in the same way.
  • the standard sieve (mesh) used in the particle size measurement may be appropriately added depending on the particle size of the object. For example, a standard sieve having an opening of 710 ⁇ m, 600 ⁇ m, or the like may be added. The method for measuring the PSD of the hydrogel polymer will be described later.
  • Residual Monomers means the amount of monomer (monomer) remaining in the water-absorbent resin (hereinafter, referred to as “residual monomer”). Specifically, 1.0 g of a water-absorbent resin was added to 200 ml of a 0.9% by weight aqueous sodium chloride solution, and the amount of dissolved monomer (unit: ppm) after stirring at 500 rpm for 1 hour using a 35 mm stirrer chip was determined. Say. The amount of the dissolved monomer is measured using HPLC (high performance liquid chromatography). The residual monomer of the hydrogel polymer was measured by changing the sample to 2 g and the stirring time to 3 hours, and converting the measured value to the weight of the hydrogel polymer per solid resin. (Unit: ppm).
  • “Moisture Content” (ERT430.2-02) “Moisture Content” means the water content of the water absorbent resin. Specifically, it is a value (unit:% by weight) calculated from the loss on drying when 1 g of the water absorbent resin is dried at 105 ° C. for 3 hours.
  • the water content of the water-absorbent resin and the dried polymer was measured by changing the drying temperature to 180 ° C.
  • the moisture content of the hydrogel polymer was measured by changing the sample to 2 g, the drying temperature to 180 ° C., and the drying time to 16 hours.
  • the value calculated by ⁇ 100-water content (% by weight) ⁇ is referred to as "resin solid content", and can be applied to a water-absorbent resin, a dried polymer, and a hydrogel polymer.
  • Liquid permeability refers to the fluidity of a liquid passing between particles of a swollen gel under a load or no load, and as a typical measurement method, SFC (Saline Flow Conductivity / physiology) is used. Saline flow inducibility) and GBP (Gel Bed Permeability / gel bed permeability).
  • SFC physiological saline flow conductivity
  • FSR Free Swell Rate
  • a water absorption rate free swelling rate
  • gel pulverization refers to an operation of applying shear and compressive force to reduce the size and increase the surface area with the aim of facilitating drying of the hydrogel polymer obtained in the polymerization step. That means.
  • gel pulverization a particulate hydrogel polymer, in particular, a particulate hydrogel polymer having a weight average particle diameter (D50) described below is obtained.
  • gel polymerization is performed after polymerization in non-stirring aqueous polymerization (static aqueous polymerization, particularly belt polymerization), whereas in kneader polymerization, polymerization and gel pulverization are performed continuously in the same apparatus.
  • the weight average particle diameter (D50) of the particulate hydrogel polymer supplied to the drying step may be in the range described below, and gel pulverization may be performed during or after polymerization. .
  • Weight average molecular weight of water-soluble component refers to the weight-average molecular weight of a component (water-soluble component) that dissolves when a water-absorbent resin is added to an aqueous solvent, by GPC (gel permeation chromatography). It refers to the measured value (unit: daltons / hereinafter, abbreviated as [Da]). That is, it is the result of GPC measurement of the solution obtained by the measurement method described in the above (1-3) (c) “Ext”.
  • the weight-average molecular weight of the water-soluble component of the hydrogel polymer was determined by changing the particle diameter to 5 mm or less, and further, to 5.0 g for a sample having a fine particle size of 1 to 3 mm, and changing the stirring time to 24 hours. A measurement was made.
  • the present invention comprises a polymerization step of polymerizing an aqueous monomer solution containing a monomer and a polymerization initiator to obtain a hydrogel polymer, and, if necessary, a polymerization step.
  • the present invention provides a method for producing a water-absorbing resin having a water absorption capacity (CRC) of 15 g / g or more and containing a chelating agent, and the following methods 1 and 2.
  • CRC water absorption capacity
  • the persulfate used in the above polymerization step is 0 to 0.04 mol% (based on the monomer at the time of polymerization) (however, when the persulfate is 0 mol% (unused), another polymerization initiator is used). ), And the chelating agent is added to the aqueous monomer solution or the hydrogel polymer in a step prior to the drying step in a total of 10 ppm or more (solid content of the monomer or the hydrogel polymer at the time of polymerization).
  • the weight-average particle diameter (D50) of the particulate hydrogel polymer is 1 mm or less, and in the drying step, the drying time until the solid content is 80% by weight or more is 20 minutes or less. And a method for producing a water-absorbent resin containing a chelating agent.
  • Method 2 Persulfate in hydrogel polymer / gel particle size / drying conditions are specified
  • the weight average particle diameter (D50) containing 10 ppm or more of the chelating agent (based on the solid content of the hydrogel polymer) and 0 to 0.04 mol% of the persulfate (based on the monomer at the time of polymerization).
  • A) A method for producing a water-absorbent resin containing a chelating agent, wherein a particulate hydrogel polymer having a particle size of 1 mm or less is dried for a drying time of 20 minutes or less until the solid content becomes 80% by weight or more.
  • the drying time refers to a time until the solid content becomes 80% by weight or more.
  • hydrogel a monomer aqueous solution containing a monomer and a polymerization initiator is polymerized to obtain a hydrogel polymer (hereinafter sometimes abbreviated as “hydrogel”). It is a process.
  • the water-absorbent resin obtained by the present invention preferably uses a monomer containing acrylic acid (salt) as a main component as its raw material (monomer), and is usually polymerized in an aqueous solution state. (Salt) -based water-absorbing resin.
  • the concentration of the monomer (monomer) in the aqueous monomer solution is preferably 10 to 80% by weight, more preferably 20 to 80% by weight, still more preferably 30 to 70% by weight, and particularly preferably 40 to 60% by weight. .
  • a monovalent salt selected from alkali metal salts, ammonium salts, and amine salts is preferable, alkali metal salts are more preferable, and sodium salts, lithium salts, and potassium salts.
  • Alkali metal salts selected from salts are more preferable, and sodium salts are particularly preferable.
  • the basic substance used for the neutralization is not particularly limited, but includes hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, sodium (hydrogen) carbonate, potassium (hydrogen) carbonate, and the like.
  • Monovalent basic substances such as carbonic acid (hydrogen) salt are preferred, and sodium hydroxide is particularly preferred.
  • carbonate is used for neutralization, carbon dioxide is generated at the time of neutralization, so that the carbon dioxide can be used as a foaming agent at the time of polymerization.
  • the above-mentioned neutralization can be performed in each form and state before, during or after the polymerization.
  • non-neutralized or low-neutralized eg, a neutralization ratio of 0 to 30 mol% acrylic acid
  • Neutralization of the hydrogel polymer obtained by polymerizing the polymer can be carried out, particularly neutralization simultaneously with gel pulverization.However, from the viewpoint of improving productivity and physical properties, neutralization of acrylic acid before polymerization is carried out. It is preferred to do so. That is, it is preferable to use neutralized acrylic acid (partially neutralized salt of acrylic acid) as a monomer.
  • the neutralization ratio in the neutralization is not particularly limited, but is preferably from 10 to 100 mol%, more preferably from 30 to 95 mol%, further preferably from 45 to 90 mol%, as a final water-absorbing resin. Particularly preferred is ⁇ 80 mol%.
  • the neutralization temperature is not particularly limited, but is preferably from 10 to 100 ° C, more preferably from 30 to 90 ° C.
  • a hydrophilic or hydrophobic unsaturated monomer other than acrylic acid (salt) (hereinafter referred to as “other monomer”) ) May be used in combination.
  • Such other monomers are not particularly limited, but include, for example, methacrylic acid, (anhydrous) maleic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acryloxyalkanesulfonic acid, N -Vinyl-2-pyrrolidone, N-vinylacetamide, (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) Examples include acrylate, polyethylene glycol (meth) acrylate, stearyl acrylate, and salts thereof.
  • the amount used is appropriately determined within a range that does not impair the water absorbing performance of the obtained water-absorbing resin, and is not particularly limited, but is based on the total monomers (excluding the internal crosslinking agent).
  • 0 to 50 mol% is preferable, 0 to 30 mol% is more preferable, and 0 to 10 mol% is further preferable.
  • the aqueous monomer solution may optionally contain a polymerization inhibitor for the purpose of stabilizing polymerization and neutralization.
  • a polymerization inhibitor for the purpose of stabilizing polymerization and neutralization.
  • the amount used is typically 200 ppm or less, more preferably 10 to 130 ppm, based on the monomer, from the viewpoints of coloring and polymerization stability. More preferably, it is 20 to 100 ppm.
  • a methoxyphenol-based polymerization inhibitor is used. More preferably, the polymerization inhibitor is p-methoxyphenol.
  • the aqueous monomer solution further contains a polymerization initiator.
  • the polymerization initiator suitably used in the present invention is appropriately selected depending on the polymerization mode, and is not particularly limited, but is preferably a radical polymerization initiator.
  • the persulfate in the polymerization initiator used in the polymerization step is reduced to 0 to 0.04 mol% (based on the monomer at the time of polymerization) (however, the persulfate is 0 mol % (Unused), another polymerization initiator is used essentially).
  • the persulfate contained in the particulate hydrogel polymer is controlled to 0 to 0.04 mol% (monomer at the time of polymerization), This is a method for controlling the gel particle diameter and the drying conditions of the hydrogel polymer. Thereby, the present invention suppresses the decomposition of the chelating agent in the drying step.
  • the persulfate can be added not only to the monomer but also to the hydrogel polymer, from the polymerization step to before the drying step. It is more preferable to control the total amount of the persulfate added to 0 to 0.04 mol% (based on the monomer at the time of polymerization).
  • the addition amount of the persulfate and the content of the persulfate in the hydrogel polymer are preferably as low as possible, and are preferably 0.04 mol% or less, 0.035 mol% or less based on the monomer at the time of polymerization.
  • the persulfate is 0.0001 mol% or more, preferably 0.001 mol% or more, more preferably, from the viewpoint of reducing the residual monomer during drying. It is desirable that the amount is contained in the monomer aqueous solution or the hydrogel polymer in an amount of 0.01 mol% or more.
  • the upper and lower limits of the amount of persulfate to be added may be in any combination.
  • the addition amount of the persulfate exceeds 0.04 mol% based on the monomer at the time of polymerization, unreacted persulfate coexists in the hydrogel polymer in the subsequent drying step. It is not preferable because it reacts with a chelating agent and can decompose it.
  • the radical polymerization initiator used in the present invention may be a persulfate (eg, sodium persulfate, potassium persulfate, ammonium persulfate, etc.), and a peroxide other than the persulfate (eg, hydrogen peroxide, t -Butyl peroxide, methyl ethyl ketone peroxide, etc.), an azo polymerization initiator, or a photopolymerization initiator.
  • a persulfate eg, sodium persulfate, potassium persulfate, ammonium persulfate, etc.
  • a peroxide other than the persulfate eg, hydrogen peroxide, t -Butyl peroxide, methyl ethyl ketone peroxide, etc.
  • azo polymerization initiator used in the present invention examples include water-soluble azo compounds (eg, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [2- (2-imidazoline- 2-yl) propane] dihydrochloride, 2,2 ′- ⁇ azobis (2-methyl-N- [1,1′-bis (hydroxymethyl) -2-hydroxyethyl] propionamide) ⁇ and the like.
  • 2,2'-azobis (2-methylpropionamidine) dihydrochloride is used.
  • the photopolymerization initiator used in the present invention includes diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, and 4- (2-hydroxyethoxy) phenyl- Acetophenone derivatives such as (2-hydroxy) -2-propyl ketone and 1-hydroxycyclohexyl phenyl ketone; benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; methyl o-benzoyl benzoate Benzophenone derivatives such as, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, (4-benzoylbenzyl) trimethylammonium chloride; thioxanthone Compound, bis (2,4,6-trimethylbenzoyl) - phenyl phosphine
  • the amount of the polymerization initiator containing a persulfate (0 to 0.04 mol%) is preferably 0.0001 to 1 mol% in total, preferably 0.0005 to 0 mol%, based on the monomers used in the polymerization. 0.5 mol% is more preferred. When the amount of the polymerization initiator exceeds 1 mol%, it is difficult to control the polymerization, and further, the color tone of the obtained water-absorbent resin may be deteriorated. When the amount of the polymerization initiator is less than 0.0001 mol%, there is a concern that the amount of the residual monomer may increase.
  • two or more polymerization initiators may be used in combination.
  • a persulfate is preferably used in the above range from the viewpoint of handleability, physical properties of the water-absorbing resin, and the like.
  • a second polymerization initiator selected from an azo polymerization initiator and a photopolymerization initiator as a polymerization initiator other than the persulfate from the viewpoint of the performance of the water-absorbing resin.
  • the molar ratio of the persulfate to the polymerization initiator other than the persulfate is from 1/99 to 99/1, preferably from 1/9 to 99/1.
  • the ratio is 9/1, more preferably 2/8 to 8/2, and still more preferably 3/7 to 7/3.
  • a redox initiator can be obtained by using together a reducing agent which promotes the decomposition of these polymerization initiators (particularly persulfate or peroxide) and combining them.
  • a reducing agent include (bis) sulfite (salt) such as sodium sulfite and sodium hydrogen sulfite, reducing metals (salt) such as L-ascorbic acid (salt) and ferrous salt, amines and the like. Is mentioned.
  • the polymerization is carried out by irradiating the reaction system with an active energy ray such as radiation, an electron beam, or an ultraviolet ray.
  • an active energy ray such as radiation, an electron beam, or an ultraviolet ray.
  • the reaction may be started.
  • persulfate includes sodium persulfate (half-life ( ⁇ ) at 90 ° C .; 1.24 hours), potassium persulfate (half-life ( ⁇ ) at 90 ° C .; 1.24 hours), ammonium persulfate (90 C .; half-life (.tau.) At 0.44 hours), and sodium persulfate is more preferred.
  • sodium acrylate is used as the monomer of the water-absorbent resin, if persulfate is used in the above range as the polymerization initiator, it will be substantially sodium persulfate regardless of the type of salt.
  • the half life ( ⁇ ) of sodium or potassium persulfate is 2100 hours (30 ° C.), 499 hours (40 ° C.), 130 hours (50 ° C.), 36.5 hours (60 ° C.), 11 0.1 hour (70 ° C.), 3.59 hours (80 ° C.), 1.24 hours (90 ° C.), and 0.45 hours (100 ° C.). Therefore, sodium persulfate or potassium persulfate remains mostly (more than 80%) in the hydrogel polymer before drying.
  • the aqueous monomer solution further contains an internal crosslinking agent.
  • the internal cross-linking agent suitably used in the present invention is not particularly limited, and includes, for example, a polymerizable cross-linking agent that polymerizes with acrylic acid, a reactive cross-linking agent that reacts with a carboxyl group, or a cross-linking agent having these properties. Is mentioned.
  • polymerizable crosslinking agent examples include N, N′-methylenebisacrylamide, (poly) ethylene glycol di (meth) acrylate, (polyoxyethylene) trimethylolpropane tri (meth) acrylate, and poly (meth) allyloxy.
  • examples include compounds having at least two polymerizable double bonds in the molecule, such as alkanes.
  • the reactive cross-linking agent examples include polyglycidyl ethers such as ethylene glycol diglycidyl ether; polyhydric alcohols such as propanediol, glycerin and sorbitol; covalent cross-linking agents such as; and polyvalent metals such as aluminum salts.
  • an ion-bonding crosslinking agent such as a compound.
  • a polymerizable crosslinker that polymerizes with acrylic acid is more preferable, and an acrylate, allyl, or acrylamide polymerizable crosslinker is particularly preferable.
  • One of these internal crosslinking agents may be used alone, or two or more thereof may be used in combination.
  • the mixing ratio is preferably from 10: 1 to 1:10.
  • the amount of the internal crosslinking agent used is preferably 0.001 to 5 mol%, more preferably 0.002 to 2 mol%, and more preferably 0.04 to 1 mol%, based on the monomer. More preferably, it is 0.06 to 0.5 mol%, most preferably 0.07 to 0.2 mol%.
  • the aqueous monomer solution contains acrylic acid (salt) in an amount of 50 to 100 mol% of the total monomers (excluding the internal cross-linking agent), and the internal cross-linking agent in an amount of 0. It is preferable to contain 001 to 5 mol%, and 0 to 0.04 mol% of the persulfate based on the monomer.
  • the water-absorbing resin composed of the polyacrylic acid (salt) -based crosslinked polymer obtained from the monomer aqueous solution can exhibit a preferable numerical range as the L value and the YI value of the initial color tone.
  • a further conventional additive may be added to the aqueous monomer solution in order to improve the physical properties of the water-absorbent resin obtained in the present invention.
  • additives examples include water-soluble resins or water-absorbing resins such as starch, cellulose, polyvinyl alcohol (PVA), polyacrylic acid (salt), and polyethyleneimine; carbonates, various foaming agents that generate air bubbles; surfactants And the like.
  • additives can be added to the hydrogel polymer, the dried polymer, the water-absorbing resin, or the like in any of the production steps of the present invention, in addition to the monomer aqueous solution.
  • the amount of these additives is preferably 0 to 50% by weight, more preferably 0 to 20% by weight, and still more preferably 0 to 10% by weight, based on the monomer. %, Particularly preferably 0 to 3% by weight.
  • the foaming agent or the surfactant it is preferably 0 to 5% by weight, more preferably 0 to 1% by weight, based on the monomer.
  • the graft polymer or the water-absorbent resin composition can be obtained by adding the above-mentioned water-soluble resin or water-absorbent resin.
  • These starch-acrylic acid polymer, PVA-acrylic acid polymer and the like are also used in the present invention. Treat as
  • a chelating agent is added to the aqueous monomer solution or the hydrogel polymer in a step prior to the drying step in a total of 10 ppm or more (for the monomer at the time of polymerization or the hydrogel polymer). Solids).
  • the content of the chelating agent of the particulate hydrogel polymer (solid content of the hydrogel polymer) provided in the drying step is 10 ppm or more, 40 ppm or more, 60 ppm or more, 100 ppm or more. , 200 ppm or more, 250 ppm or more, 500 ppm or more, and 600 ppm or more in this order.
  • the upper limit of the amount of the chelating agent or the upper limit of the content is determined by the solid content of the monomer or the hydrogel polymer at the time of polymerization. It is preferable that the content is 1% or less, 8000 ppm or less, 6000 ppm or less, and 5000 ppm or less. In the present invention, any combination of the upper limit and the lower limit of the added amount or the content of the chelating agent is preferable.
  • the above-mentioned added amount (ppm) of the chelating agent is the weight of the chelating agent at the time of addition (to the monomer at the time of polymerization or the solid content of the hydrogel polymer), and is a single amount after mixing after addition.
  • the salt exchange with the carboxy group of the polymer and the polymer is not taken into account, and the neutralized salt type chelating agent shows the amount of addition as a salt type, and the acid type chelating agent shows the actual addition amount as an acid type.
  • the weight% of the chelating agent with respect to the solid content of the monomer or the hydrogel polymer can be converted into a molar ratio (mol%) to the monomer at the time of polymerization.
  • the added amount or the content of the chelating agent is 0.0002 mol% or more, 0.001 mol% or more, 0.002 mol% or more, 0.005 mol% or more based on the monomer at the time of polymerization. , 0.01 mol% or more in this order.
  • the upper limit is preferably in the order of 0.2 mol% or less, 0.15 mol% or less, 0.12 mol% or less, and 0.1 mol% or less.
  • the upper and lower limits of the molar ratio of the chelating agent may be in any combination.
  • the molar ratio of the persulfate to the chelating agent is preferably lower, more preferably 50 times or less, 20 times or less, 10 times or less, 5 times or less, 3 times or less, The lower limit is 0.
  • the residual ratio of the chelating agent is improved, and not only the content of the chelating agent in the polymer in the obtained water-absorbent resin is increased, but also the L value of the initial coloring of the obtained water-absorbent resin is increased. Increase and the YI value decreases.
  • the chelating agent By adding a chelating agent to the monomer at the time of polymerization or the hydrogel before drying, the chelating agent is uniformly blended into the polymer of the water-absorbing resin (particularly, the water-absorbing resin of the final product) after the drying step. be able to.
  • the chelating agent is selectively added to the surface of the water-absorbent resin by adding the chelating agent after the drying step and further in the surface cross-linking step or subsequent steps.
  • the effect of the chelating agent can be further enhanced by blending the chelating agent inside the polymer.
  • a chelating agent When a chelating agent is added in the above-mentioned polymerization step, it can be added to the aqueous monomer solution as in the case of other additives.
  • gel pulverization can be performed by adding and kneading to the hydrogel polymer.
  • an aqueous solution containing a chelating agent can be supplied into the gel crusher while the hydrogel polymer is retained in the gel crusher.
  • an aqueous solution containing a chelating agent may be added in advance to the hydrogel polymer and charged into the gel pulverizer. The timing of adding these chelating agents may be appropriately combined.
  • a high-molecular or non-polymer chelating agent more preferably a non-polymer chelating agent, further preferably a non-polymer chelating agent having a molecular weight of 1,000 or less can be mentioned.
  • the chelating agent used in the present invention include amino polyvalent carboxylic acid, organic polyvalent phosphoric acid (particularly, amino polyvalent phosphoric acid), inorganic polyvalent phosphoric acid, and tropolone derivatives. At least one chelating agent selected from the group consisting of these compounds is used in the present invention.
  • polyvalent refers to having a plurality of functional groups in one molecule, preferably 2 to 30, more preferably 3 to 20, and still more preferably 4 to 10. Refers to having a functional group.
  • amino polycarboxylic acid specifically, imino diacetic acid, hydroxyethyl imino diacetic acid, nitrilotriacetic acid, nitrilotripropionic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid (DTPA), triethylenetetramine hexaacetic acid (TTHA), trans -1,2-diaminocyclohexane tetraacetic acid, N, N-bis (2-hydroxyethyl) glycine, diaminopropanol tetraacetic acid, ethylenediamine-2-propionic acid, N-hydroxyethylethylenediamine triacetic acid, glycol ether diamine tetraacetic acid , Diaminopropanetetraacetic acid, N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-2acetic acid, 1,6-hexamethylenediamine-N, N
  • organic polyvalent phosphoric acid examples include nitriloacetic acid-di (methylenephosphinic acid), nitriloacetic acid- (methylenephosphinic acid), nitriloacetic acid- ⁇ -propionic acid-methylenephosphonic acid, and nitrilotris (methylenephosphonic acid). Acid), 1-hydroxyethylidene diphosphonic acid, amino polyphosphoric acid and the like.
  • amino polyvalent phosphoric acid examples include ethylenediamine-N, N′-di (methylenephosphinic acid), ethylenediaminetetra (methylenephosphinic acid), cyclohexanediaminetetra (methylenephosphonic acid), ethylenediamine-N, N '-Diacetic acid-N, N'-di (methylene phosphonic acid), ethylenediamine-N, N'-di (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), polymethylenediaminetetra (methylenephosphonic acid), diethylenetriamine Penta (methylene phosphonic acid), ethylenediaminetetramethylene phosphonic acid (EDTMP), and salts thereof.
  • ethylenediamine-N, N′-di methylenephosphinic acid
  • ethylenediaminetetra methylenephosphinic acid
  • cyclohexanediaminetetra methylenephosphonic acid
  • inorganic polyvalent phosphoric acid examples include pyrophosphoric acid, tripolyphosphoric acid, and salts thereof.
  • tropolone derivative examples include tropolone, ⁇ -thiaprisin, ⁇ -thiaprisin, and the like.
  • an amino polycarboxylic acid chelating agent and / or an amino polyphosphoric acid chelating agent are preferable.
  • the amino polycarboxylic acid chelating agent specifically, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and triethylenetetraaminehexaacetic acid, and metal salts thereof, for example, sodium salt, potassium salt and the like Is mentioned.
  • the amino polyvalent phosphoric acid chelating agent include ethylenediaminetetramethylenephosphonic acid.
  • a water-absorbent resin containing a chelating agent uniformly in a polymer can be obtained by such a technique.
  • the deterioration and coloring of the water-absorbing resin are easily performed on the particle surface. Therefore, in the present invention, by adding a chelating agent to the surface of the particles by adding a chelating agent to the water-absorbing resin in a step after the drying step, that is, by adding the chelating agent a plurality of times, the water absorbing
  • the type and amount of the chelating agent to be added in the steps after the drying step may be the same as or different from the type and the amount of the chelating agent to be added in the step before the drying step. It is preferable to use the following types and addition amounts. Further, the chelating agent may be added to the monomer or the hydrogel polymer only with the chelating agent, or may be added to the monomer or the hydrogel polymer in the form of a solution (particularly an aqueous solution). Good.
  • the polymerization method comprises directly obtaining a particulate hydrogel polymer by spray / droplet polymerization or reverse phase suspension polymerization in the gas phase. From the viewpoint of the liquid permeability (SFC) and water absorption rate (FSR) of the obtained water-absorbent resin, ease of polymerization control, etc., aqueous solution polymerization is adopted.
  • SFC liquid permeability
  • FSR water absorption rate
  • a hydrogel polymer may be obtained by a tank type (silo type) or belt type non-stirring polymerization, and may be separately subjected to gel pulverization.
  • the reaction may be carried out to obtain a particulate hydrogel polymer, but from the viewpoint of easy control of polymerization, preferably, kneader polymerization or belt polymerization is employed. Further, from the viewpoint of productivity, continuous aqueous solution polymerization, more preferably, high-concentration continuous aqueous solution polymerization is employed.
  • stirring polymerization means that a hydrogel polymer (especially, a hydrogel polymer having a polymerization rate of 10 mol% or more, more preferably 50 mol% or more) is polymerized while being stirred, particularly with stirring and fragmentation. Before and after the non-stirring polymerization, the aqueous monomer solution (polymerization rate: 0 to less than 10 mol%) may be appropriately stirred.
  • Examples of the continuous aqueous solution polymerization include continuous kneader polymerization described in U.S. Patent Nos. 6,987,171 and 6,710,141 and U.S. Patent Nos. 4,893,999 and 6,241,928, and U.S. Patent Application Publication No. 2005 / 215,734. Continuous belt polymerization. By such aqueous solution polymerization, a water-absorbent resin can be produced with high productivity.
  • the decomposition of the chelating agent during drying can be suppressed by increasing the solid content concentration of the hydrogel polymer by high concentration polymerization and shortening the drying step.
  • the monomer concentration (solid content) is preferably 35% by weight or more, more preferably 40% by weight or more, and even more preferably 45% by weight or more (the upper limit is the saturation concentration).
  • the polymerization initiation temperature is preferably 30 ° C. or higher, more preferably 35 ° C. or higher, still more preferably 40 ° C. or higher, and particularly preferably 50 ° C. or higher (the upper limit is the boiling point).
  • the polymerization peak temperature is usually preferably from 80 to 130 ° C., more preferably from the boiling point of high-temperature polymerization to 120 ° C.
  • high-concentration, high-temperature initiation polymerization is a combination of these, and the aqueous monomer solution tends to boil during the polymerization, and a solvent such as water evaporates, so that a high-solids hydrogel polymer is obtained.
  • the solid content of the hydrogel polymer is preferably from 40 to 75% by mass, more preferably from 45 to 70% by mass, and still more preferably from 50 to 65% by mass.
  • the decomposition of the chelating agent in the drying step is reduced, and the residual ratio of the chelating agent is improved.
  • the solid content of the hydrogel polymer exceeds 75% by mass, the physical properties of the obtained water-absorbing resin may be deteriorated.
  • the polymerization in the present invention is preferably foam polymerization or boiling polymerization.
  • the residual monomer is 0.1% by mass or more, and more preferably 0.5 to 10% by mass, in the hydrogel polymer before the drying step. %, About 0.5 to 5% by weight, and about 0.5 to 3% by weight. In order to allow almost 100% of the chelating agent to remain in the polymerization step, it is preferable from the above estimation mechanism that the polymerization time be short in order to sufficiently leave unreacted monomer at the end of the polymerization step.
  • the present invention is preferably applied to short-time polymerization in which the polymerization time is 60 minutes or less, 10 minutes or less, 5 minutes or less, 3 minutes or less (the lower limit of the polymerization time is 1 second, and more preferably 10 seconds or more). .
  • the polymerization conditions include a polymerization initiation temperature of 30 ° C. or higher (further in the above range) and a polymerization peak temperature of 80 to 130 ° C. Range), high-temperature short-time polymerization with a polymerization time of 60 minutes or less (and further in the above range) is particularly preferable, and high-concentration and high-temperature short-time polymerization in which the monomer concentration is 35% by weight or more (and further in the above range). Is most preferred.
  • the polymerization method in the production method according to the present invention is preferably applied to a large-scale production apparatus having a large production volume per line.
  • the production amount is preferably 0.5 t / hr or more, more preferably 1 t / hr or more, still more preferably 5 t / hr or more, and particularly preferably 10 t / hr or more.
  • the above polymerization can be carried out in an air atmosphere, but is preferably carried out in an atmosphere of an inert gas such as steam, nitrogen or argon (for example, an oxygen concentration of 1% by volume or less) from the viewpoint of preventing coloration. Furthermore, it is preferable to carry out polymerization after replacing (degassing) the dissolved oxygen in the monomer or the solution containing the monomer with an inert gas (for example, less than 1 mg / L of oxygen). Even if such degassing is performed, the stability of the monomer is excellent, gelation before polymerization does not occur, and a water absorbing resin having higher physical properties and higher whiteness can be provided.
  • an inert gas such as steam, nitrogen or argon
  • Gel pulverizing step This step is a step of obtaining a particulate hydrogel polymer by fragmenting the hydrogel polymer during or after the polymerization described above. This step is referred to as “gel pulverization” in distinction from “pulverization” in the following (2-4) pulverization step / classification step.
  • a particulate hydrogel polymer is obtained in the gel pulverizing step during and / or after the polymerization step, or directly in the polymerization step. It is more preferable to obtain a particulate hydrogel polymer in the gel pulverizing step during and / or after the polymerization step.
  • the gel crusher used during or after polymerization used in this step is not particularly limited, and a gel crusher equipped with a plurality of rotary stirring blades, such as a batch-type or continuous-type double-arm kneader, or a single-shaft crusher may be used.
  • An extruder, a twin-screw extruder, a meat chopper, especially a screw type extruder and the like can be mentioned.
  • a screw type extruder in which a perforated plate is provided at one end of the casing is preferable, and specific examples include a screw type extruder disclosed in JP-A-2000-63527 and WO2011 / 126079.
  • JP-A-2000-63527 JP-A-2000-63527
  • WO2011 / 126079 Can be
  • the gel pulverization is performed during and / or after the polymerization step, and more preferably is performed on the hydrogel polymer after the polymerization step.
  • the state in which the aqueous monomer solution is "sufficiently gelled" is defined as a gel pulverizing step.
  • the aqueous monomer solution changes into a hydrogel polymer as the polymerization time elapses. That is, the stirring region of the aqueous monomer solution at the start of the polymerization, the stirring region of the low-polymerized hydrogel polymer having a constant viscosity during the polymerization, the gel of a part of the hydrogel polymer as the polymerization proceeds.
  • the pulverization start area and the gel pulverization area at the latter or late stage of polymerization are continuously performed. Therefore, in order to clearly distinguish between “stirring of the aqueous monomer solution” at the start of the polymerization and “gel pulverization” at the end, the judgment is made based on the state of “sufficiently gelled”.
  • the term “sufficiently gelled” refers to a state in which the hydrogel polymer can be finely divided by applying a shearing force after the time when the polymerization temperature reaches a maximum (polymerization peak temperature).
  • the polymerization rate of the monomer in the monomer aqueous solution also known as a conversion rate; the polymerization rate is preferably calculated from the amount of the polymer calculated from the pH titration of the hydrogel polymer and the amount of the remaining monomer
  • a hydrogel polymer having a monomer polymerization rate within the above range is gel-pulverized.
  • a polymerization reaction that does not show the above-mentioned polymerization peak temperature (for example, when the polymerization always proceeds at a constant temperature or when the polymerization temperature keeps increasing)
  • “sufficient gelation” is performed with the polymerization rate of the monomer. Stipulate.
  • a hydrogel polymer in the middle and / or after the polymerization step preferably a hydrogel polymer after the polymerization step is reduced to about several tens cm. Can be cut or crushed to size. By this operation, it becomes easy to fill the hydrogel polymer into the gel pulverizer, and the gel pulverization step can be performed more smoothly.
  • the means for cutting or crushing is preferably a means capable of cutting or crushing the hydrogel polymer without kneading, for example, a guillotine cutter or the like.
  • the size and shape of the hydrogel polymer obtained by cutting or crushing are not particularly limited as long as they can be filled in a gel crusher.
  • water can be added to the hydrogel polymer to carry out gel pulverization.
  • water takes any form of solid, liquid, and gas.
  • the water may be supplied into the gel crusher while the hydrated gel polymer remains in the gel crusher.
  • water may be added in advance to the hydrogel polymer and charged into the gel pulverizer.
  • the water is not limited to “water alone”, and other additives (for example, a surfactant, a neutralizing base, a crosslinking agent, and the like) and a solvent other than water may be added.
  • the content of water is preferably from 90 to 100% by weight, more preferably from 99 to 100% by weight, even more preferably substantially 100% by weight.
  • the water can be used in any form of solid, liquid, and gas, but liquid and / or gas is preferable from the viewpoint of handleability.
  • the amount of water to be supplied is preferably 0 to 25 parts by weight, preferably 0 to 15 parts by weight, 0 to 10 parts by weight, 0 to 4 parts by weight, 0 to 2 parts by weight based on 100 parts by weight of the hydrogel polymer. Are more preferable.
  • the supply amount of water is more than 25 parts by weight, it becomes difficult to control the particle size of the hydrogel polymer, the drying time becomes longer, the remaining amount of the chelating agent decreases, May be generated. From the viewpoint of drying efficiency, it is preferable that the supply amount of water in this step does not exceed the amount of the solvent evaporated in the polymerization step, particularly, the amount of evaporated water.
  • the temperature during the supply is preferably 10 to 100 ° C, more preferably 40 to 100 ° C.
  • the temperature during the supply is preferably 100 to 220 ° C., more preferably 100 to 160 ° C., and further preferably 100 to 130 ° C.
  • the preparation method is not particularly limited. For example, a method using water vapor generated by heating a boiler, a method in which water is vibrated by ultrasonic waves, and a gas state generated from the water surface is used. And the like utilizing water.
  • steam having a pressure higher than the atmospheric pressure is preferable, and steam generated in a boiler is more preferable.
  • the hydrogel polymer obtained in the above polymerization step is pulverized into particles by using a gel pulverizer (kneader, meat chopper, screw type extruder, etc.) to which the above-described gel pulverization of the present invention is applied.
  • a gel pulverizer kneader, meat chopper, screw type extruder, etc.
  • the gel particle size can be controlled by classification, preparation, etc., but preferably the gel particle size is controlled by the gel pulverization of the present invention.
  • the weight-average particle diameter (D50) (defined by sieve classification) of the particulate hydrogel polymer after gel pulverization is 1 mm or less, and is 10 ⁇ m to 1 mm, 20 ⁇ m to 1 mm, 40 ⁇ m to 1 mm, 50 ⁇ m to 900 ⁇ m. More preferred in order.
  • the upper limit of the weight average particle diameter is more preferably 800 ⁇ m or less, 700 ⁇ m or less, and 600 ⁇ m or less.
  • the lower limit of the weight average particle diameter is more preferably 100 ⁇ m or more and 200 ⁇ m or more. In the present invention, the upper limit and the lower limit of the weight average particle diameter may be in any combination.
  • the gel particle diameter can be measured by the method described in WO2011 / 126079.
  • the addition of the special method as described above requires a large amount of a surfactant or an organic solvent for polymerization and classification, decreases productivity (increases costs) and deteriorates physical properties ( (Residual monomer increase and fine powder increase), which may cause new problems. For this reason, it may be difficult to obtain a particulate hydrogel polymer having a weight average particle diameter of less than 10 ⁇ m.
  • the gel CRC of the particulate hydrogel polymer after gel pulverization is preferably from 10 to 35 g / g, more preferably from 10 to 32 g / g, even more preferably from 15 to 30 g / g.
  • the gel CRC after gel pulverization is preferably -1 to +3 g / g, more preferably 0.1 to 2 g / g, and more preferably 0.3 to 1.5 g, relative to the gel CRC before gel pulverization. / G is more preferred.
  • the gel CRC may be reduced by using a cross-linking agent at the time of gel pulverization, but it is preferable to increase the gel CRC within the above range.
  • the gel Ext of the particulate hydrogel polymer after gel pulverization is preferably 0.1 to 20% by weight, more preferably 0.1 to 10% by weight, and 0.1 to 8% by weight. More preferred is 0.1 to 5% by weight.
  • the increase amount of the gel Ext of the particulate hydrogel polymer after gel pulverization is preferably 5% by weight or less, more preferably 4% by weight or less, and 3% by weight.
  • the content is particularly preferably 2% by weight or less, and most preferably 1% by weight or less.
  • the lower limit may be minus (for example, -3.0% by weight, or even -1.0% by weight), but is usually 0% by weight or more, preferably 0.1% by weight or more, and more preferably 0.1% by weight or more. It is at least 2% by weight, more preferably at least 0.3% by weight.
  • the gel Ext is increased so as to fall within the arbitrary range of the above-mentioned upper limit and lower limit, such as preferably 0 to 5.0% by weight, more preferably 0.1 to 3.0% by weight.
  • the gel may be crushed until it is done.
  • the gel Ext may be reduced by using a cross-linking agent at the time of gel pulverization, but it is preferable to increase the gel Ext within the above range.
  • the effective number of the increase amount of the gel Ext is one digit after the decimal point. For example, 5% by weight and 5.0% by weight are treated as synonyms.
  • the lower limit of the weight-average molecular weight of the water-soluble component of the hydrogel polymer after gel pulverization is 10,000 Da. Or more, more preferably 20,000 Da or more, and even more preferably 30,000 Da or more.
  • the upper limit is preferably 500,000 Da or less, more preferably 400,000 Da or less, further preferably 250,000 Da or less, and particularly preferably 100,000 Da or less.
  • the increase in the weight average molecular weight of the water-soluble portion of the particulate hydrogel polymer after gel pulverization relative to the hydrogel polymer before gel pulverization is 10,000 to 500,000 Da. It is preferably 20,000 to 400,000 Da, more preferably 30,000 to 250,000 Da, and further preferably 100,000 Da or less.
  • the resin solid content of the particulate hydrogel polymer after gel pulverization is preferably from 40 to 75% by mass, more preferably from the viewpoint of physical properties.
  • the content is 45 to 70% by mass, and more preferably 50 to 65% by mass.
  • the hydrogel polymer before gel pulverization is evaluated based on the weight-average molecular weight of the water-soluble component, but it is necessary that this value be a sufficiently averaged value. .
  • the production amount of the water-absorbent resin is 1 to 20 t / hr or 1 to 10 t / hr by continuous gel pulverization using a continuous kneader or meat chopper, two or more points are obtained for every 100 kg of the hydrogel polymer. At least 10 points or more may be sampled and measured in total, and in the case of batch-type gel pulverization (for example, a batch-type kneader), at least 10 points or more are sampled and measured from a batch sample to obtain particulate water-containing powder. The physical properties of the gel polymer may be evaluated.
  • This step is a step of drying the particulate hydrogel polymer pulverized to the specific particle size in the gel pulverizing step to obtain a dry polymer.
  • a drying method preferably applied in the present invention will be described.
  • the particulate hydrogel containing the chelating agent is dried.
  • the chelating agent does not substantially decrease at the time of polymerization or after completion of the drying step, and the chelating agent is decomposed during the drying step by remaining persulfate.
  • the amount of persulfate remaining in the drying step it is preferable to control the amount of persulfate remaining in the drying step to be low. Further, in order to suppress the decomposition of the chelating agent, it is preferable to perform rapid drying in the drying step.
  • the particle diameter of the hydrogel polymer is reduced, specifically, the weight average particle diameter (D50) of the particulate hydrogel polymer is controlled to 1 mm or less, and the drying time is 20 minutes or less. It is particularly preferable to dry until the solid content becomes 80% by weight or more. However, the drying time refers to the time until the solid content becomes 80% by weight or more.
  • the content of the persulfate in the particulate hydrogel polymer subjected to the drying step is specifically 0.04 to the monomer at the time of polymerization. It is preferable in the order of mol% or less, 0.035 mol% or less, 0.03 mol% or less, 0.025 mol% or less, 0.02 mol% or less, and 0.015 mol% or less.
  • the lower limit of the amount of persulfate added is 0 mol%, which means that it is not used during polymerization or is completely consumed before the drying step.
  • the persulfate is effective in reducing the residual monomer, the persulfate is 0.0001 mol% or more, preferably 0.001 mol% or more, more preferably, from the viewpoint of reducing the residual monomer during drying. It is desirable that the amount is contained in the monomer aqueous solution or the hydrogel polymer in an amount of 0.01 mol% or more.
  • the residual ratio of the chelating agent is improved, and not only the amount of the chelating agent inside the polymer in the obtained water-absorbent resin is increased, but also the L value of the initial coloring of the obtained water-absorbent resin is increased. , YI values decrease.
  • the upper and lower limits of the amount of persulfate to be added may be in any combination.
  • the persulfate content in the hydrogel polymer can be measured by the method described in WO2007 / 116778.
  • the content of the chelating agent of the particulate hydrogel polymer (based on the solid content of the hydrogel polymer) provided in the drying step is 10 ppm or more, and 40 ppm or more.
  • the above is preferred in the order of at least 60 ppm, at least 100 ppm, at least 200 ppm, at least 250 ppm, at least 500 ppm, and at least 600 ppm.
  • the upper limit of the content of the chelating agent is 1% or less and 8000 ppm or less based on the solid content of the hydrogel polymer.
  • the upper limit and the lower limit of the content of the chelating agent may be in any combination.
  • the content of the above chelating agent indicates the apparent weight ppm concentration when added as a chelating agent without considering salt exchange with the carboxy group of the monomer and the polymer after mixing.
  • a hot air heat transfer type dryer As a drying device used in the drying step, a hot air heat transfer type dryer (hereinafter, referred to as “hot air dryer”) is preferable from the viewpoint of a drying speed. That is, hot air drying is preferable as the drying method.
  • the hot air dryer include a ventilation belt (band) type, a ventilation circuit type, a vertical ventilation type, a parallel flow belt (band) type, a ventilation tunnel type, a ventilation groove type stirring type, a fluidized bed type, an air flow type, a spray type and the like.
  • a hot air dryer is mentioned.
  • a ventilation belt type hot air dryer is preferable from the viewpoint of physical property control.
  • the wind direction of the hot air used in the dryer is a water-containing layer which is laminated on the ventilation belt and allowed to stand still. It is preferable that the direction is perpendicular to the gel polymer layer (for example, both in the vertical direction or in the upward and downward directions).
  • the “vertical direction” refers to the vertical direction (from the top to the bottom of the gel layer) with respect to the gel layer (a particulate hydrogel polymer having a thickness of 10 to 300 mm laminated on a punching metal or metal net).
  • a state in which air is passed from the bottom to the top of the gel layer is not limited to a strictly vertical direction as long as air is passed in the vertical direction.
  • hot air in an oblique direction may be used. In this case, it is within 30 ° with respect to the vertical direction, preferably within 20 °, more preferably within 10 °, even more preferably within 5 °, and particularly preferably 0 °. ° hot air is used.
  • drying conditions and the like in the drying step of the present invention will be described.
  • the drying temperature in the drying step of the present invention is 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and particularly preferably 150 ° C. or higher. Further, the drying temperature is 200 ° C. or lower, preferably 190 ° C. or lower, more preferably 180 ° C. or lower. In the present invention, any combination of the upper limit and the lower limit of the drying temperature is preferable. If the drying temperature is lower than 80 ° C., the drying time until a suitable resin solid content (moisture content) is obtained is long, and the decomposition rate of the chelating agent is undesirably increased.
  • the drying temperature refers to the temperature of the heating medium used for drying in the case of direct heating, the temperature of hot air used for drying in the case of hot air drying, and the heat transfer surface used for drying in the case of indirect heating. Refers to the temperature of
  • the drying time in the drying step of the present invention refers to the time until the solid content becomes 80% by weight or more, and is preferably 20 minutes or less, more preferably 18 minutes or less, 15 minutes or less, and 12 minutes or less.
  • the lower limit of the drying time is about 1 minute in consideration of the drying efficiency. It has also been found that the decomposition of the chelating agent occurs mainly in the drying stage until the solids content reaches 80% by weight. Further, the total drying time in the present invention is preferably 60 minutes or less, more preferably 50 minutes or less, and more preferably 40 minutes or less. If the drying time is short, undried matter is generated, and clogging may occur during the subsequent pulverization step.
  • the rate of decomposition of the chelating agent is undesirably increased.
  • the step of heating the particulate hydrogel polymer in a dryer to raise the temperature is also included in the drying step. Shall be taken.
  • the start of the drying time is when the hydrogel polymer is placed in the dryer, and the total drying time is after the hydrogel polymer is placed in the dryer, and the hydrogel polymer is dried and dried. It is the time until it is taken out of the machine.
  • the temperature for moving and the temperature of the hydrogel polymer at the time of moving to the dryer entrance are specifically 30 ° C. or lower. It is preferable to use a combination of not more than 90 minutes, not more than 20 minutes at 90 ° C, not more than 10 minutes at not more than 100 ° C, and not more than 5 minutes at 110 ° C.
  • the hydrogel polymer obtained in the polymerization step can be once cooled to 40 ° C. or lower, left for a long time, and then introduced into the drying step.
  • the particulate hydrogel obtained in the above-mentioned gel pulverizing step is dried in the above-mentioned drying step to be a dried polymer.
  • the resin solid content determined from the loss on drying of the dried polymer is preferably 80% by weight or more, more preferably 85 to 99% by weight, More preferably, it is 90 to 98% by weight.
  • the velocity of the hot air in the through-air dryer is preferably 0.8 to 2.5 m / s in the vertical direction (vertical direction), and is 1.0 to 2.5 m / s. 2.02.0 m / s is more preferable.
  • the wind speed may be controlled within a range that does not impair the effects of the present invention.
  • the wind speed may be controlled within a range of 70% or more of the drying time, preferably 90% or more, and more preferably 95% or more.
  • the above-mentioned wind speed is represented by an average flow velocity of hot air passing in a direction perpendicular to a horizontally moving band surface, taking a ventilation belt type dryer as an example. Therefore, the average flow velocity of the hot air may be obtained by dividing the amount of air blown to the ventilation belt dryer by the area of the ventilation belt.
  • the hot air used in the ventilation belt type dryer preferably contains at least water vapor and has a dew point of 30 to 100 ° C, more preferably 30 to 80 ° C.
  • the dew point is a value at the time when the water content of the particulate hydrogel polymer is at least 10% by weight or more, preferably 20% by weight or more.
  • the dew point near the dryer outlet (or at the end of drying; for example, 50% or more of the drying time) is closer to the dryer inlet.
  • the dew point is high (or early in the drying; for example, before 50% of the drying time).
  • the particulate hydrogel polymer is continuously supplied in a layer form on a belt of a ventilation belt type dryer. , Hot air dried.
  • the width of the belt of the ventilation belt type dryer used at this time is not particularly limited, but is preferably 0.5 m or more, more preferably 1 m or more.
  • the upper limit is preferably 10 m or less, more preferably 5 m or less.
  • the length of the belt is preferably 20 m or more, and more preferably 40 m or more.
  • the upper limit is preferably 100 m or less, more preferably 50 m or less.
  • the layer length (thickness of the gel layer) of the particulate hydrogel polymer on the belt is preferably 10 to 300 mm, more preferably 50 to 200 mm, and more preferably 80 to 150 mm from the viewpoint of solving the problems of the present invention. Is more preferable, and 90 to 110 mm is particularly preferable.
  • the moving speed of the particulate hydrogel polymer on the belt may be appropriately set according to the belt width, the belt length, the production amount, the drying time, etc., but from the viewpoint of the load of the belt driving device, durability and the like. From this, it is preferably 0.3 to 5 m / min, more preferably 0.5 to 2.5 m / min, further preferably 0.5 to 2 m / min, and particularly preferably 0.7 to 1.5 m / min.
  • the method for producing a water-absorbent resin containing a chelating agent according to the present invention further includes a pulverizing step and a classifying step of pulverizing and classifying the dried polymer obtained in the drying step. May be.
  • This step is different from the above-mentioned (2-2) gel pulverizing step in that the resin solid content at the time of pulverization, particularly the point that the object to be pulverized has undergone a drying step (preferably, the resin solid content is dried).
  • the water-absorbing resin obtained after the pulverizing step may be referred to as a pulverized product.
  • the dried polymer obtained in the drying step can be used as it is as a water-absorbing resin, but it is preferable to control the particle size to a specific particle size in order to improve the physical properties in the surface treatment step described below, particularly in the surface crosslinking step. .
  • the particle size control is not limited to the main pulverization step and the classification step, but can be appropriately performed in the polymerization step, the fine powder recovery step, the granulation step, and the like.
  • the pulverizer that can be used in the pulverization step is not particularly limited.
  • a vibration mill, a roll granulator, a knuckle-type pulverizer, a roll mill, a high-speed rotary pulverizer (pin mill, hammer mill, screw mill), cylindrical A mixer etc. can be mentioned.
  • a multi-stage roll mill or roll granulator from the viewpoint of particle size control.
  • the classification operation is performed so as to have the following particle size.
  • the classification operation is preferably performed before the surface cross-linking step (first classification step), and further after the surface cross-linking.
  • a classification operation (second classification step) may also be performed.
  • the first classification step is usually performed after the pulverizing step, but may be further performed before the pulverizing step.
  • the weight-average particle size (D50) of the water-absorbent resin particles after classification is not particularly limited, and can be appropriately adjusted according to the application.
  • the weight-average particle size (D50) of the classified water-absorbent resin particles is preferably 200 to 800 ⁇ m, more preferably 200 to 600 ⁇ m, and further preferably 300 to 500 ⁇ m.
  • the proportion of particles having a particle diameter of 850 to 150 ⁇ m is preferably 90% by weight or more, more preferably 95% by weight or more, and even more preferably 97% by weight or more.
  • the water-absorbent resin as the final product is also preferably in the form of particles, and the above-described range of the particle diameter is applied.
  • the method for producing a water-absorbent resin containing a chelating agent according to the present invention preferably further includes a surface treatment step for controlling physical properties.
  • the surface treatment step includes a surface cross-linking step performed using a known surface cross-linking agent and a surface cross-linking method, and further includes other addition steps as necessary.
  • the chelating agent does not decrease in the surface crosslinking or heating step.
  • the surface cross-linking agent As the surface cross-linking agent that can be used in the present invention, various organic or inorganic surface cross-linking agents can be exemplified, and preferably, an organic surface cross-linking agent can be used.
  • the surface crosslinking agent is preferably a polyhydric alcohol compound, an epoxy compound, a polyvalent amine compound or a condensate thereof with a haloepoxy compound, an oxazoline compound, a (mono, di, or poly) oxazolidinone compound, or an alkylene carbonate compound.
  • a dehydration-reactive cross-linking agent comprising a polyhydric alcohol compound, an alkylene carbonate compound, and an oxazolidinone compound, which requires a reaction at a high temperature
  • a dehydration-reactive cross-linking agent comprising a polyhydric alcohol compound, an alkylene carbonate compound, and an oxazolidinone compound, which requires a reaction at a high temperature
  • the dehydration-reactive cross-linking agent is not used, more specifically, compounds exemplified in U.S. Pat. Nos. 6,228,930, 6,071,976 and 6,254,990 can be exemplified.
  • Such compounds include, for example, mono, di, tri, tetra or propylene glycol, 1,3-propanediol, glycerin, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, Polyhydric alcohol compounds such as 6-hexanediol and sorbitol; epoxy compounds such as ethylene glycol diglycidyl ether and glycidol; alkylene carbonate compounds such as ethylene carbonate; oxetane compounds; and cyclic urea compounds such as 2-imidazolidinone. No.
  • the amount of the surface cross-linking agent to be used is appropriately determined, preferably in the range of about 0.001 to 10 parts by weight, more preferably about 0.01 to 5 parts by weight, based on 100 parts by weight of the water absorbent resin particles.
  • Water is preferably used according to the surface crosslinking agent.
  • the amount of water used is preferably 0.5 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the water absorbent resin particles.
  • the amount is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the water absorbent resin particles. Is done.
  • a hydrophilic organic solvent may be used, and the amount of the organic solvent is preferably from 0 to 10 parts by weight, more preferably from 0 to 5 parts by weight, based on 100 parts by weight of the water-absorbing resin particles. It is.
  • the effect of the present invention is not impaired, for example, preferably 0 to 10 parts by weight, more preferably 0 to 5 parts by weight, and still more preferably 0 to 1 part by weight.
  • a water-insoluble fine particle powder and a surfactant may coexist.
  • the surfactant used and the amount used are exemplified in U.S. Pat. No. 7,473,739.
  • the surface crosslinking agent solution When the surface crosslinking agent solution is mixed with the water-absorbing resin particles, the water-absorbing resin particles swell due to water or the like in the surface crosslinking agent solution.
  • the swollen water-absorbent resin particles are dried by heating.
  • the heating temperature is preferably from 80 to 220 ° C.
  • the heating time is preferably from 10 to 120 minutes.
  • a vertical or horizontal high-speed stirring type mixer is preferably used for mixing the surface crosslinking agent.
  • the rotation speed of the mixer is preferably 100 to 10000 rpm, and more preferably 300 to 2000 rpm.
  • the residence time is preferably within 180 seconds, more preferably 0.1 to 60 seconds, further preferably 1 to 30 seconds.
  • a surface cross-linking method using a radical polymerization initiator (US Pat. No. 4,783,510, WO 2006/062258) instead of the surface cross-linking using the surface cross-linking agent, and water absorption
  • a surface cross-linking method of polymerizing a monomer on the surface of a conductive resin (US Patent Application Publication Nos. 2005/048221, 2009/0239966, and International Publication No. 2009/048160) may be used.
  • the radical polymerization initiator preferably used is persulfate, and arbitrarily preferably used monomers include acrylic acid (salt) and the above-described surface cross-linking agent, and water is preferably used as a solvent.
  • surface crosslinking is performed by performing a cross-linking polymerization or a cross-linking reaction with a radical polymerization initiator on the surface of the water-absorbent resin by active energy rays (especially ultraviolet rays) or heating.
  • active energy rays especially ultraviolet rays
  • the present invention may further include an addition step of adding at least one of a polyvalent metal salt, a cationic polymer, and inorganic fine particles simultaneously with or separately from the above-described surface crosslinking step. That is, in addition to the organic surface cross-linking agent, an inorganic surface cross-linking agent may be used or used in combination to improve the liquid permeability and the water absorption rate.
  • the inorganic surface crosslinking agent can be used simultaneously with or separately from the organic surface crosslinking agent.
  • the inorganic surface cross-linking agent to be used include salts (organic salts or inorganic salts) or hydroxides of divalent or higher, preferably trivalent or tetravalent polyvalent metals.
  • the polyvalent metal that can be used include aluminum and zirconium, and specifically, aluminum lactate and aluminum sulfate. Preferably, it is an aqueous solution containing aluminum sulfate.
  • a recycling step of the evaporated monomer a granulation step, a fine powder removing step, a fine powder recycling step, and the like may be provided.
  • the following additives may be used, if necessary, for any or all of them. That is, a water-soluble or water-insoluble polymer, a lubricant, a deodorant, an antibacterial agent, water, a surfactant, water-insoluble fine particles, an antioxidant, a reducing agent, and the like are preferably added to the water-absorbing resin in an amount of 0 to 30. % By weight, more preferably 0.01 to 10% by weight.
  • These additives can also be used as a surface treatment agent.
  • the production method of the present invention can include a fine powder recycling step.
  • the fine powder recycling process is a process in which fine powder (especially fine powder containing 70% by weight or more of powder having a particle diameter of 150 ⁇ m or less) generated in a drying step and, if necessary, a crushing step and a classifying step is separated and is used as it is or in water. It refers to a step of recycle to a polymerization step and a drying step, and a method described in U.S. Patent Application Publication No. 2006/247351 or U.S. Patent No. 6,228,930 can be applied.
  • oxidizing agents such as antioxidants, water, polyvalent metal compounds, water-insoluble inorganic or organic powders such as silica and metal soap, deodorants, antibacterial agents, high-molecular polyamines, pulp and thermoplastic fibers And the like may be added to the water-absorbent resin in an amount of 0 to 3% by weight, preferably 0 to 1% by weight.
  • Water-absorbing resin The present invention provides a water-absorbing resin containing a chelating agent, which is obtained by the above-described production method according to the present invention.
  • a water-absorbing resin containing a chelating agent obtained by the above-described production method according to the present invention.
  • various physical properties of the water-absorbing resin containing the chelating agent according to the present invention will be described.
  • the water-absorbing resin containing a chelating agent obtained by the production method according to the present invention is preferably a polyacrylic acid (salt) -based crosslinked polymer water-absorbing resin.
  • the residual amount (C1) of the chelating agent of the water-absorbing resin is determined by taking into account the salt exchange with the carboxy group of the monomer and polymer after mixing, the neutralized salt type chelating agent as a salt type, and the acid type chelating agent. The agent shows the remaining amount as it is when added as an acid form.
  • the content (C2) of the chelating agent of the water-absorbing resin indicates the content as an acid-type chelating agent.
  • the amount is the same as the remaining amount (C1) of the chelating agent, and when the chelating agent is in the salt form, the concentration is calculated as the acid form of the same chelating agent.
  • the content (C2) of the chelating agent is calculated by “the remaining amount of the chelating agent (C1) ⁇ the molecular weight of the acid form / the molecular weight at the time of adding the chelating agent”.
  • the remaining rate (%) of the chelating agent is calculated by “ ⁇ (remaining amount of chelating agent (C1) [ppm]) / (adding amount of chelating agent [ppm]) ⁇ ⁇ 100”.
  • the residual amount (C1) and content (C2) of the chelating agent in the water-absorbent resin according to the present invention are 10 ppm or more, 40 ppm or more, 60 ppm or more, 100 ppm or more, 200 ppm or more, 250 ppm from the viewpoint of prevention of coloring and deterioration prevention. More preferably, the order is 500 ppm or more and 600 ppm or more. Further, the upper limit of the remaining amount (C1) and the content (C2) of the chelating agent in the water-absorbing resin according to the present invention is 1% by weight from the viewpoint of the effect (prevention of coloring, deterioration prevention, etc.) and cost of the chelating agent. Hereinafter, 8000 ppm or less, 6000 ppm or less, and 5000 ppm or less are preferable.
  • the residual ratio of the chelating agent is preferably 50% or more, and more preferably 60% or more.
  • the residual ratio of the chelating agent is defined as the amount of the chelating agent added to the water-absorbent resin in the production process [ppm] (based on the solid content of the monomer at the time of polymerization or the solid content of the hydrogel polymer). It is the ratio [%] of the remaining amount (C1) [ppm] of the chelating agent.
  • the residual rate of the chelating agent is defined as the chelating agent content of the final product with respect to the sum of the content of the chelating agent in the final product and the amount obtained by converting the amount (ppm) of the decomposition product derived from the chelating agent into the content of the chelating agent. It may be determined from the ratio of the contents of the agent.
  • the water-absorbing resin according to the present invention is a water-absorbing resin that can be suitably used for sanitary materials such as disposable diapers, and is preferably a white powder.
  • the water-absorbent resin according to the present invention has an L value (Lightness: lightness index) of an initial color tone (also referred to as “initial coloring”) of at least 85, and more preferably 89 or more, in a Hunter Lab color system measurement using a spectral colorimeter. , Preferably 90 or more.
  • the upper limit of the L value is usually 100, but if the value is 85 for powder, no problem due to the color tone occurs in products such as sanitary materials.
  • the initial color tone is a color tone after the production of the water-absorbent resin, but is generally a color tone measured before shipment from the factory. Further, for example, in the case of storage in an atmosphere of 30 ° C. or lower and a relative humidity of 50% RH, the value is measured within one year after production.
  • the water-absorbent resin according to the present invention has an initial color tone YI value (yellowness; yellowness index) of 0 to 13, 0 to 10, 0 to 9, 0 to 7, 0 to 5, and 0 to 3 in this order. Preferably, there is almost no yellowing.
  • a method for producing a water-absorbent resin containing the chelating agent according to the present invention wherein the persulfate in the polymerization initiator used in the polymerization step is 0 to 0.04 mol%.
  • the persulfate in the polymerization initiator used in the polymerization step is 0 to 0.04 mol%.
  • another polymerization initiator is indispensable
  • the chelating agent is used in the step before the drying step.
  • a total of 10 ppm or more solid content of the monomer at the time of polymerization or the solid content of the hydrogel polymer
  • the weight average particle diameter of the particulate hydrogel polymer is increased.
  • the remaining amount of the chelating agent (C1) is 10 ppm as a final product by a manufacturing method in which the drying time until the solid content becomes 80% by weight or more is 20 minutes or less.
  • the L value of the initial color tone is 85 A top, it is possible to produce a water-absorbent resin YI value is 13 or less.
  • a total of 200 ppm or more (solid content of the monomer at the time of polymerization or the solid content of the hydrogel polymer) was added to the aqueous monomer solution or the hydrogel polymer, and the weight average particle of the particulate hydrogel polymer was added.
  • the diameter (D50) is set to 1 mm or less, and in the drying step, the remaining amount of the chelating agent (C1) is determined as a final product by a manufacturing method in which the drying time until the solid content becomes 80% by weight or more is 20 minutes or less.
  • the content (C2) of the chelating agent is 200 ppm or more (further in the above range), the L value of the initial color tone is 89 or more (further in the above range), and the YI value is 10 or less.
  • the present invention provides a polyacrylic acid (salt) -based water-absorbent resin having the above range).
  • a water-absorbent resin wherein the water-absorbent resin contains a chelating agent on the surface and inside, and the amount of the chelating agent present on the surface is larger than the amount of the chelating agent present inside. I do.
  • the shape of the water-absorbent resin of the present invention is not particularly limited as long as it can be handled as a powder, but is preferably an irregular crushed shape.
  • the amorphous crushed shape is a particle shape having an irregular shape obtained by crushing a hydrogel polymer or a dried polymer.
  • the weight average particle size (D50) of the water absorbent resin of the present invention is preferably from 200 to 800 ⁇ m, more preferably from 200 to 600 ⁇ m, and still more preferably from 300 to 500 ⁇ m. Further, the proportion of particles having a particle diameter of 850 to 150 ⁇ m is preferably 90% by weight or more, more preferably 95% by weight or more, and even more preferably 97% by weight or more.
  • the water-absorbent resin of the present invention having the above-mentioned particle size is easy to handle, and easily exhibits water-absorbing performance with sanitary materials and the like.
  • the water absorption capacity under no pressure (CRC) of the water-absorbent resin according to the present invention is preferably higher, more preferably 15 g / g. g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, and particularly preferably 33 g / g or more.
  • the upper limit of the CRC is preferably 60 g / g or less, more preferably 50 g / g or less, and still more preferably 45 g / g or less, from the viewpoint of balance with other physical properties (for example, absorbency against pressure (AAP)). is there.
  • CRC can be controlled by the crosslinking density at the time of polymerization or surface crosslinking.
  • the CRC is less than 15 g / g, the cross-linking density of the water-absorbent resin is high, so that the effect of preventing deterioration by the chelating agent is difficult to appear.
  • the water-absorbing resin is used as a sanitary material such as a disposable diaper, the water-absorbing efficiency deteriorates, which is not preferable.
  • the water absorption capacity under pressure (AAP (0.7 psi)) of the water-absorbent resin according to the present invention is controlled to preferably 15 g / g or more, more preferably 20 g / g or more, and further preferably 23 g / g or more.
  • the upper limit of AAP (0.7 psi) is preferably 40 g / g or less, more preferably 35 g / g or less, and still more preferably from the viewpoint of balance with other physical properties (for example, water absorption capacity under no pressure (CRC)). Is 33 g / g or less.
  • AAP (0.7 psi) can be controlled by the crosslinking density at the time of surface crosslinking.
  • the ratio of the water absorption capacity under pressure to the water absorption capacity under no pressure (AAP (0.7 psi) / CRC) of the water-absorbent resin according to the present invention is 0.5 or more, 0.6 or more, 0.7 or more, and 0. 8 or more, preferably 0.9 or more.
  • the upper limit of AAP (0.7 psi) / CRC is about 1.5 or less, 1.2 or less, and about 1.0 or less. While CRC removes interstitial water between gels after swelling by centrifugation, AAP (0.7 psi) has a water absorption capacity that includes interstitial water, so AAP (0.7 psi) may exceed CRC. However, the upper limit is usually within the above range.
  • the use of the water absorbent resin obtained by the production method according to the present invention is not particularly limited, but it is preferably used for absorbent articles such as paper diapers, sanitary napkins, incontinence pads, and the like.
  • the water-absorbent resin obtained by the production method according to the present invention is a high-concentration diaper (a paper diaper that uses a large amount of the water-absorbent resin per paper diaper), in which odors and coloring derived from raw materials have been a problem. Particularly, when used in the upper layer portion of the absorbent article, excellent performance is exhibited.
  • the proportion of the water-absorbing resin contained in the absorbent body of the disposable diaper is preferably at least 50% by weight, more preferably at least 60% by weight, at least 70% by weight, at least 80% by weight, and at least 90% by weight.
  • the present inventors have found that a chelating agent added in a step prior to a drying step in a drying step of a hydrogel polymer obtained by polymerizing a monomer. Was found to decrease specifically.
  • the present inventors have found that the cause of the decrease in the chelating agent in the drying step is a polymerization initiator (particularly, persulfate) remaining in the hydrogel polymer.
  • the present invention controls persulfate in a polymerization initiator at the time of polymerization or before drying (0.04 mol% or less), and further controls gel particle diameter and drying conditions before drying. Of the chelating agent in the drying step.
  • Patent Documents 1 to 23 disclose the use of a chelating agent in the process of producing a water absorbent resin.
  • Persulfates are the most widely used polymerization initiators for water-absorbing resins, and Patent Documents 1 to 23 also disclose persulfates as polymerization initiators.
  • Patent Documents 1 to 23 described above there is no description about the problems pointed out in the present application and means for solving the problems, let alone decomposition of the chelating agent by persulfate.
  • the persulfate in the polymerization initiator is 0 to 0.04 mol% (based on the monomer at the time of polymerization) (0 mol% is not used during the polymerization or is completely consumed before the drying step.
  • a hydrogel polymer (solid content: ⁇ wt%) at a temperature of 20 to 25 ° C. is mixed with a 20 wt% aqueous sodium chloride solution containing 0.08 wt% emal 20C (surfactant, manufactured by Kao Corporation) (Hereinafter referred to as "emar aqueous solution”) was added to 500 g to form a dispersion, and the mixture was stirred at 300 rpm for 60 minutes using a stirrer chip having a length of 50 mm and a diameter of 7 mm (a cylinder made of polypropylene having a height of 21 cm and a diameter of 8 cm). 1.14 L container is used).
  • the percentage by weight was calculated from the following formula (1).
  • the particle size distribution of the hydrogel polymer was plotted on log probability paper according to the following formula (2). From this graph, the particle diameter corresponding to the residual percentage of 50% by weight was read as the weight average particle diameter (D50) of the hydrogel polymer.
  • the particulate water-absorbing resin is added to 100 g of physiological saline (a 0.9% by weight aqueous solution of sodium chloride), and the mixture is stirred at room temperature for 1 hour (stirring speed: 500 ⁇ 50 rpm).
  • physiological saline a 0.9% by weight aqueous solution of sodium chloride
  • the chelating agent was extracted into physiological saline.
  • the obtained filtrate was passed through a filter for HPLC sample pretreatment (Chromatodisk 25A / water-based type, pore size: 0.45 ⁇ m / manufactured by Kurashiki Spinning Co., Ltd.), and the filtrate was subjected to high-performance liquid chromatography (HPLC). The content of the chelating agent therein was measured.
  • the content of the chelating agent in the particulate water-absorbent resin is determined by taking into account the dilution ratio of the particulate water-absorbent resin to physiological saline using the calibration curve obtained by measuring a standard solution of known concentration as an external standard. I asked.
  • the HPLC measurement conditions were appropriately changed depending on the type of the chelating agent. Specifically, the following measurement conditions 1 were used for diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), and nitrilotriacetic acid (NTA), and the following measurement conditions 2 were used for ethylenediaminetetra (methylenephosphonic acid) (EDTMP). Quantification was performed according to the above.
  • Measurement condition 1 ⁇ Eluent>; 0.3 ml of 0.4 mol / L alum aqueous solution, 450 ml of 0.1 N potassium hydroxide aqueous solution, 3 ml of 0.4 mol / L aqueous solution of tetra-n-butylammonium hydroxide, 3 ml of sulfuric acid, ethylene glycol Mixed solution of 1.5 ml and ion-exchanged water 2550 ml ⁇ Column>; LichroCART 250-4 Superspher 100 RP-18e (4 ⁇ m) (Merck Co., Ltd.) ⁇ Column temperature>; 23 ⁇ 2 ° C ⁇ Flow rate>; 1 ml / min ⁇ Detector>; UV, wavelength 258 nm.
  • Measurement condition 2 ⁇ Eluent>; 0.003 mol / L aqueous sulfuric acid solution ⁇ Column>; Shodex IC NI-424 (manufactured by Showa Denko KK) ⁇ Column temperature>; 40 ° C ⁇ Flow rate>; 1 ml / min ⁇ Detector>; RI Since the content of the chelating agent is affected by the water content, in the present invention, the content is a value corrected for the water content, and is a value converted per 100 parts by weight of the water-absorbent resin solids.
  • the chelating agent to be added is of an anionic type, for convenience, it is considered that the salt of the added chelating agent is present in the water-absorbent resin without salt exchange.
  • the content (C2) of the chelating agent is the same as the remaining amount of the chelating agent (C1) when the chelating agent is of the acid type. If the chelating agent is in salt form, the concentration is calculated as the acid form of the same chelating agent. That is, the content (C2) of the chelating agent was calculated by “the remaining amount of the chelating agent (C1) ⁇ the molecular weight of the acid form / the apparent molecular weight when the chelating agent was added”.
  • the remaining ratio (%) of the chelating agent was calculated by “ ⁇ (remaining amount of chelating agent [ppm]) / (addition amount of chelating agent [ppm]) ⁇ ⁇ 100”.
  • the L value Lightness: lightness index
  • the YI value yellowness; yellowness index
  • the paste sample table was filled with about 5 g of a water-absorbent resin and adjusted to an atmosphere of 70 ⁇ 1 ° C. and a relative humidity of 65 ⁇ 1% (product name: small environmental tester manufactured by Espec Corporation). , Type SH-641) filled with a water-absorbent resin was exposed for 7 days. This exposure is a 7-day color acceleration test. After the exposure, the L value (Lightness) and the YI value (yellowness) in the Hunter Lab color system on the surface were measured by the above-mentioned spectral colorimeter. This measured value is referred to as “coloring with time (70 ⁇ 1 ° C., relative humidity 65 ⁇ 1%, 7 days)”. The higher the L value, the better, and the lower the YI value, the lower the coloration and the closer to substantially white.
  • the absorbance of an aqueous solution (blank) obtained by adding 0.50 g of a 44% by weight aqueous solution of potassium iodide to 5 g of an aqueous sodium solution was set to 0).
  • 5 wt% aqueous sodium chloride solutions containing 0 ppm (not added), 5 ppm, 10 ppm, 15 ppm, and 20 ppm of persulfate were prepared, and the absorbance was determined by the above operation to prepare a calibration curve. Then, the amount (ppm) of persulfate in the hydrogel of the sample was calculated from the absorbance of the obtained sample and the calibration curve. Further, the amount (mol%) of the persulfate was determined by calculation.
  • the amount of persulfate can be measured in the same manner for the water-absorbent resin after drying.
  • the measurement limit is appropriately determined depending on the amount of polymer, sensitivity, and the like.
  • the detection limit is usually 0.5 ppm, and below the detection limit is expressed as ND (Non-Detactable).
  • (F) Solid content of hydrogel polymer The solid content of the particulate hydrogel polymer was measured in the same manner as in the above-mentioned method of measuring “solid content of water-absorbent resin”. However, the amount of the hydrogel polymer was changed to about 2 g, the drying temperature was changed to 180 ° C., and the drying time was changed to 24 hours.
  • CRC is an abbreviation of Centrifuge Retention Capacity (centrifuge retention capacity), and means a non-pressurized water absorption capacity (hereinafter sometimes referred to as “water absorption capacity”). Specifically, 0.200 g of the water-absorbent resin in the non-woven fabric bag was freely swelled in a large excess of 0.9% by weight aqueous sodium chloride solution for 30 minutes, and then drained with a centrifuge. Magnification (unit: [g / g]) was measured.
  • AAP (0.7 psi) (ERT442.2-02) “AAP” is an abbreviation for Absorption against Pressure, and means the water absorption capacity under pressure.
  • AAP (0.7 psi) is a method in which 0.900 g of a water-absorbing resin is applied to a 0.9% by weight aqueous sodium chloride solution for 1 hour at 4.83 kPa (0.7 psi, 49 [g / cm 2 ]). The water absorption capacity (unit: [g / g]) after swelling was measured.
  • Residual monomer ERT410.2-02
  • ERT410.2-02 Residual monomer 1.0 g of a water-absorbing resin was added to 200 ml of a 0.9% by weight aqueous sodium chloride solution, and stirred for 1 hour at 500 rpm using a 35 mm stirrer chip.
  • Chrromatography The residual monomer of the hydrogel polymer was measured by changing the sample to 2 g and the stirring time to 3 hours, and converting the measured value to the weight of the hydrogel polymer per solid resin. (Unit: ppm).
  • DTPA chelating agent
  • NaPS persulfate
  • gel particle size 958 ⁇ m (about 0.9 mm).
  • the solution (B) was added and mixed while stirring the solution (A) using a magnetic stirrer to prepare a solution (C).
  • the stainless steel bat type container is a container having a bottom surface size of 250 mm ⁇ 250 mm, an upper surface size of 640 mm ⁇ 640 mm, a height of 50 mm, a trapezoidal center cross section, and a silicone sheet attached to the inner surface. there were.
  • the stainless steel bat type container was placed on a hot plate (NEO HOTPLATE H1-1000, manufactured by Iuchi Seieido Co., Ltd.) heated to 100 ° C. and preheated.
  • the polymerization reaction After the aqueous monomer solution (1) expands and foams in all directions upward while generating water vapor, the polymerization reaction proceeds to a size slightly larger than the bottom surface of the stainless steel vat container. The hydrogel polymer (1) thus shrunk was completed. The polymerization reaction (expansion and shrinkage) was completed within about 1 minute, but after that, the hydrogel polymer (1) was held in the stainless steel bat type container for 3 minutes. By the polymerization reaction (boiling polymerization), a hydrogel polymer (1) containing bubbles was obtained.
  • the particulate hydrogel polymer (1) obtained by the above gel pulverization had a weight average particle size (D50) of 958 ⁇ m.
  • the residual monomer of the particulate hydrogel polymer (1) was 1.1% by weight.
  • the particulate hydrogel polymer (1) was spread and placed on a wire mesh having a mesh size of 300 ⁇ m (50 mesh) and placed in a hot-air dryer.
  • the particulate hydrogel polymer (1) was dried by passing hot air at 160 ° C. for 30 minutes to obtain a particulate dried polymer (1).
  • the dried polymer (1) was put into a roll mill (WML-type roll grinder, manufactured by Inoguchi Giken Co., Ltd.) and pulverized, and thereafter, using two kinds of JIS standard sieves having openings of 850 ⁇ m and 150 ⁇ m. By classifying, an amorphous crushed water-absorbent resin (1) was obtained.
  • WML-type roll grinder manufactured by Inoguchi Giken Co., Ltd.
  • the amorphous crushed water-absorbent resin (1) obtained by the above series of operations had a CRC of 28.9 g / g.
  • the humidified mixture (1) was uniformly placed in a stainless steel container (about 22 cm in width, about 28 cm in depth, about 5 cm in height), and was heat-treated at 180 ° C. for 40 minutes to obtain a surface-crosslinked water-absorbent resin ( 1) was obtained.
  • the surface-crosslinked water-absorbent resin (1) was passed through a JIS standard sieve having openings of 850 ⁇ m to obtain a water-absorbent resin (1) as a final product.
  • the water-absorbent resin (1) as the final product obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate hydrogel polymer (2) obtained in the gel pulverizing step had a weight average particle size (D50) of 942 ⁇ m.
  • the irregularly crushed water-absorbent resin (2) had a CRC of 28.8 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (2) as a final product.
  • the resulting water-absorbent resin (2) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • a difference between the YI value of the initial coloring and the YI value of the temporal coloring was calculated.
  • the calculation results are shown in Table 3 below.
  • Example 3 Changing the gel particle diameter of Example 1 (from about 0.9 mm to about 0.5 mm); In the above Example 1, except that after the second gel pulverization in the gel pulverization step, the obtained gel was further charged into a tabletop meat chopper to perform the third gel pulverization in order to change the gel particle diameter. In the same manner as in Example 1, a water absorbent resin (3) was produced.
  • the particulate hydrogel polymer (3) obtained in the gel pulverizing step had a weight average particle size (D50) of 514 ⁇ m (about 0.5 mm). Further, the amorphous crushed water-absorbent resin (3) had a CRC of 28.3 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (3) as a final product.
  • the water-absorbent resin (3) obtained as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 4 Changing the type of polymerization initiator in Example 1 (NaPS ⁇ azo polymerization initiator); 3.
  • the polymerization initiator was changed to an aqueous solution of 10% by weight of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (trade name; Wako Pure Chemical V-50), which is an azo polymerization initiator.
  • a water-absorbent resin (4) was produced in the same manner as in Example 1, except that the amount was changed to 34 g (0.04 mol% based on acrylic acid).
  • the particulate hydrogel polymer (4) obtained in the gel pulverizing step had a weight average particle size (D50) of 971 ⁇ m.
  • the amorphous crushed water-absorbent resin (4) had a CRC of 30.0 / g.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (4) as a final product.
  • the resulting water-absorbent resin (4) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 5 Changing the chelating agent of Example 1 (DTPA ⁇ EDTMP); Same as Example 1 except that the chelating agent was changed to a 10% by weight aqueous solution of ethylenediaminetetramethylenephosphonic acid (EDTMP) ⁇ 5 sodium (3.52 g, 1000 ppm based on monomer). Thus, a water-absorbing resin (5) was produced.
  • EDTMP ethylenediaminetetramethylenephosphonic acid
  • the particulate hydrogel polymer (5) obtained in the gel pulverizing step had a weight average particle size (D50) of 964 ⁇ m (about 0.9 mm).
  • the amorphous crushed water-absorbent resin (5) had a CRC of 28.5 g / g.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (5) as a final product.
  • the resulting water-absorbent resin (5) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate hydrogel polymer (6) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 923 ⁇ m.
  • the amorphous crushed water-absorbent resin (6) had a CRC of 29.3 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (6) as a final product.
  • the resulting water-absorbent resin (6) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 7 Changing the type of polymerization initiator of Example 5 (persulfate ⁇ azo polymerization initiator);
  • Example 5 4.34 g of a 10% by weight aqueous solution of 2,2′-azobis (2-methylpropionamidine) dihydrochloride (V-50), which is an azo polymerization initiator, was used in Example 5 (based on acrylic acid).
  • Water-absorbent resin (7) was produced in the same manner as in Example 5, except that the water-absorbent resin (7) was changed to 0.04 mol%).
  • the particulate hydrogel polymer (7) obtained in the gel pulverizing step had a weight average particle size (D50) of 933 ⁇ m.
  • the amorphous crushed water-absorbent resin (7) had a CRC of 29.1 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (7) as a final product.
  • the resulting water-absorbent resin (7) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 8 Changing the polymerization initiator of Example 5 (persulfate ⁇ UV polymerization with UV polymerization initiator); The procedure of Example 5 was repeated except that the polymerization initiator (10% by weight aqueous sodium persulfate solution) in the polymerization step was changed to a UV polymerization initiator, and the amount added was 0.04 mol% to perform UV polymerization. In the same manner as in Example 5, a water absorbent resin (8) was produced.
  • the temperature of the aqueous monomer solution (8) rose to 101.9 ° C. due to heat of neutralization and heat of dissolution generated during the mixing process.
  • the neutralization ratio of the aqueous monomer solution (8) was 73 mol%, and the monomer concentration was 43% by weight.
  • the aqueous monomer solution (8) is poured into the stainless steel vat-shaped container, and at the same time, a height of 600 mm from the bottom surface of the stainless steel vat-shaped container.
  • the monomer aqueous solution (8) was irradiated with ultraviolet rays by an ultraviolet irradiation device (Toskure # 401; Model name: HC-04131-B; Lamp: H400L / 2; manufactured by Harrison Toshiba Lighting Co., Ltd.) installed at the position of (1).
  • an ultraviolet irradiation device Toskure # 401; Model name: HC-04131-B; Lamp: H400L / 2; manufactured by Harrison Toshiba Lighting Co., Ltd.
  • the stainless steel bat type container is a container having a bottom surface size of 250 mm ⁇ 250 mm, an upper surface size of 640 mm ⁇ 640 mm, a height of 50 mm, a trapezoidal center cross section, and a silicone sheet attached to the inner surface. there were.
  • the stainless steel bat type container was placed on a hot plate (NEO HOTPLATE H1-1000, manufactured by Iuchi Seieido Co., Ltd.) heated to 100 ° C. and preheated.
  • the polymerization (static solution polymerization) proceeded while generating steam.
  • the polymerization reached a peak temperature within about 1 minute (polymerization peak temperature: 102 ° C.).
  • the irradiation of ultraviolet rays was stopped to obtain a hydrogel polymer (8) containing bubbles.
  • the particulate hydrogel polymer (8) obtained in the gel pulverizing step had a weight average particle size (D50) of 917 ⁇ m. Further, the amorphous crushed water-absorbent resin (8) had a CRC of 28.0 g / g.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (8) as a final product.
  • the resulting water-absorbent resin (8) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate comparative hydrogel polymer (1) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 900 ⁇ m.
  • the irregularly crushed comparative water-absorbent resin (1) had a CRC of 28.8 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a comparative water-absorbent resin (1) as a final product.
  • the comparative water absorbent resin (1) obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 2 Changing the gel particle diameter of Example 1 (about 0.9 mm ⁇ 5 mm or more); A comparative water-absorbent resin (2) was produced in the same manner as in Example 1 except that the gel pulverizing step was performed only once in order to change the gel particle diameter.
  • the particulate hydrogel polymer (2) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 5000 ⁇ m (5 mm) or more.
  • the amorphous crushed comparative water absorbent resin (2) had a CRC of 27.1 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a comparative water-absorbent resin (2) as a final product.
  • the comparative water absorbent resin (2) obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • a difference between the YI value of the initial coloring and the YI value of the temporal coloring was calculated.
  • the calculation results are shown in Table 3 below.
  • Example 3 Changing the gel particle diameter of Example 5 (from about 0.9 mm to 5 mm or more); A comparative water-absorbent resin (3) was produced in the same manner as in Example 5 except that the gel pulverizing step was performed once in order to change the gel particle diameter.
  • the particulate hydrogel polymer (3) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 5000 ⁇ m (5 mm) or more.
  • the amorphous crushed comparative water-absorbent resin (3) had a CRC of 27.2 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a comparative water-absorbent resin (3) as a final product.
  • the comparative water absorbent resin (3) obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate hydrogel polymer (9) obtained in the gel pulverizing step had a weight average particle size (D50) of 922 ⁇ m.
  • the amorphous crushed water-absorbent resin (9) had a CRC of 29.8 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (9) as a final product.
  • the water-absorbent resin (9) as the final product obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate hydrogel polymer (10) obtained in the gel pulverizing step had a weight average particle size (D50) of 950 ⁇ m.
  • the amorphous crushed water-absorbent resin (10) had a CRC of 30.3 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (10) as a final product.
  • the water-absorbent resin (10) as the final product obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the addition amount of DTPA ⁇ 5 sodium was set to 50 ppm with respect to the monomer, and the addition amount of the polymerization initiator (10% by weight aqueous sodium persulfate solution) was 1.43 g ( 0.015 mol% with respect to acrylic acid), and 2.71 g of an aqueous solution of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (V-50) (10% by weight) as an azo polymerization initiator (acrylic).
  • Water-absorbent resin (11) was produced in the same manner as in Example 1 except that 0.025 mol% of the acid was used in combination.
  • the particulate hydrogel polymer (11) obtained in the gel pulverizing step had a weight average particle size (D50) of 919 ⁇ m. Further, the amorphous crushed water-absorbent resin (11) had a CRC of 30.1 g / g.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (11) as a final product.
  • the resulting water-absorbent resin (11) as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 12 Changing the drying temperature and drying time in Example 1 (160 ° C. ⁇ 120 ° C., 30 minutes ⁇ 120 minutes); In the above Example 1, except that the drying temperature and the drying time in the drying step were changed to 120 ° C. for 120 minutes (hot air of 120 ° C. was passed for 120 minutes), the water absorbing resin (12 ) Manufactured.
  • the particulate hydrogel polymer (12) obtained in the gel pulverizing step had a weight average particle size (D50) of 937 ⁇ m.
  • the irregularly crushed water-absorbent resin (12) had a CRC of 26.3 g / g and a solid content of 94.3%.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (12) as a final product.
  • the water-absorbent resin (12) as the final product obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 13 Changing the drying temperature and gel particle diameter of Example 1 (160 ° C. ⁇ 120 ° C., about 0.9 mm ⁇ about 0.5 mm);
  • Example 1 in order to change the gel particle diameter, after the second gel pulverization in the gel pulverization step, the obtained gel was further charged into a tabletop meat chopper to perform the third gel pulverization,
  • a water-absorbent resin (13) was produced in the same manner as in Example 1 except that the drying temperature in the drying step was changed to 120 ° C. (hot air of 120 ° C. was passed for 30 minutes).
  • the particulate hydrogel polymer (13) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 510 ⁇ m (about 0.5 mm).
  • the amorphous crushed water-absorbent resin (13) had a CRC of 26.4 g / g and a solid content of 93.4%.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (13) as a final product.
  • the water-absorbent resin (13) obtained as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 4 Changing the drying temperature and drying time of Example 1 and the gel particle diameter (160 ° C. ⁇ 120 ° C., 30 minutes ⁇ 180 minutes, about 0.9 mm ⁇ 5 mm or more);
  • the gel pulverization in the gel pulverization step was performed once, and the drying temperature and the drying time in the drying step were set to 120 ° C. for 180 minutes (hot air of 120 ° C.).
  • a comparative water-absorbent resin (4) was produced in the same manner as in Example 1, except that the air flow was changed to 180 minutes.
  • the particulate hydrogel polymer (4) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 5000 ⁇ m (5 mm) or more.
  • the amorphous crushed comparative water-absorbent resin (4) had a CRC of 24.4 g / g and a solid content of 91.5%.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a comparative water-absorbent resin (4) as a final product.
  • the comparative water absorbent resin (4) obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 5 Changing the drying temperature and drying time of Example 1 and the gel particle size (160 ° C. ⁇ 150 ° C., 30 minutes ⁇ 180 minutes, about 0.9 mm ⁇ 1.2 to 1.6 cm);
  • the hydrogel polymer was cut using scissors as the gel pulverization in the gel pulverization step, and the size of each side was 1.2 to 1.6 cm. It was a hydrogel polymer.
  • a comparative water-absorbent resin (5) was produced in the same manner as in Example 1 except that the drying temperature and the drying time in the drying step were changed to 150 ° C. for 180 minutes (hot air at 150 ° C. was passed for 180 minutes). did.
  • the particulate hydrogel polymer (5) obtained in the gel pulverizing step had a weight average particle size (D50) of 1.2 to 1.6 cm.
  • the comparative crushed amorphous water-absorbent resin (5) had a CRC of 31.6 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a comparative water-absorbent resin (5) as a final product.
  • the obtained comparative water absorbent resin (5) was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 14 Changing the chelating agent of Example 1 (DTPA ⁇ EDTA); In the same manner as in Example 1, except that the chelating agent was changed to a 10% by weight aqueous solution of ethylenediaminetetraacetic acid (EDTA) ⁇ 4 sodium (3.52 g, 1000 ppm with respect to the monomer). And a water-absorbing resin (14).
  • EDTA ethylenediaminetetraacetic acid
  • the particulate hydrogel polymer (14) obtained in the gel pulverizing step had a weight average particle size (D50) of 955 ⁇ m (about 0.9 mm). Further, the amorphous crushed water-absorbent resin (14) had a CRC of 29.2 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a water absorbent resin (14) as a final product.
  • the water-absorbent resin (14) as the final product obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate hydrogel polymer (15) obtained in the gel pulverizing step had a weight average particle size (D50) of 930 ⁇ m. Further, the amorphous crushed water-absorbent resin (15) had a CRC of 29.5 g / g.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (15) as a final product.
  • the water-absorbent resin (15) obtained as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 16 Changing the chelating agent of Example 1 (DTPA ⁇ NTA); In the same manner as in Example 1, except that the chelating agent was changed to a 10% by weight nitrilotriacetic acid (NTA) ⁇ trisodium aqueous solution (3.52 g, 1000 ppm with respect to the monomer). And a water-absorbing resin (16).
  • NTA nitrilotriacetic acid
  • the particulate hydrogel polymer (16) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 943 ⁇ m (about 0.9 mm).
  • the amorphous crushed water-absorbent resin (16) had a CRC of 29.1 g / g.
  • Example 2 the surface was crosslinked in the same manner as in Example 1 to obtain a water absorbent resin (16) as a final product.
  • the water-absorbent resin (16) obtained as the final product was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • the particulate comparative hydrogel polymer (6) obtained in the gel pulverizing step had a weight average particle diameter (D50) of 929 ⁇ m.
  • the amorphous crushed comparative water-absorbent resin (6) had a CRC of 29.5 g / g.
  • Example 2 surface cross-linking was performed in the same manner as in Example 1 to obtain a comparative water-absorbent resin (6) as a final product.
  • the comparative water absorbent resin (6) obtained was analyzed.
  • the manufacturing conditions are shown in Table 1 below, and the analysis results are shown in Table 2 below.
  • Example 17 Hereinafter, in Example 17 and Comparative Example 7, the polymerization step and the gel pulverization step were performed simultaneously.
  • a reactor formed by attaching a lid to a double-armed jacketed stainless steel kneader having two sigma-type blades having an inner volume of 10 L, 425.2 g of acrylic acid, 4499.5 g of a 37% by weight aqueous solution of sodium acrylate, and pure After 513.65 g of water and 11.1 g of polyethylene glycol diacrylate (molecular weight: 523) were added to prepare a reaction solution, the mixture was degassed for 20 minutes in a nitrogen gas atmosphere.
  • the hydrogel crosslinked polymer (17) was removed from the reactor.
  • the obtained particulate hydrogel polymer (17) had a weight average particle size (D50) of 479 ⁇ m.
  • the finely divided hydrogel crosslinked polymer (17) was spread on a metal mesh having a mesh size of 300 ⁇ m (50 mesh) and placed in a hot air drier. Then, the particulate hydrogel polymer (17) was dried by passing hot air at 170 ° C. for 30 minutes to obtain a particulate dry polymer (17). Subsequently, the dried polymer (17) was put into a roll mill (WML type roll pulverizer, manufactured by Inoguchi Giken Co., Ltd.) and pulverized. By classifying, an amorphous crushed water-absorbent resin (17) was obtained. In addition, the amorphous crushed water-absorbent resin (17) had a CRC of 31.8 g / g.
  • Example 17 After drying in the same manner as in Example 17 to obtain a comparative dry polymer (7) in the form of particles, it is pulverized and classified to obtain a comparative crushed amorphous water-absorbent resin (7) having a size of 850 to 150 ⁇ m. Obtained.
  • Comparative Example 8 A comparative water-absorbent resin (8) was obtained according to the method described in Example 1-8 of International Publication No. 2011/040530 (Patent Document 17). The resulting final product, comparative water-absorbent resin (8), was analyzed. The analysis results are shown in Table 3 below. The manufacturing conditions and analysis results are shown in Tables 1 to 3 below.
  • Comparative water-absorbent resin (9) was obtained according to the method described in Example 2-23 of International Publication WO 2014/054656 (Patent Document 23). The resulting final product, comparative water-absorbent resin (9), was analyzed. The manufacturing conditions and analysis results are shown in Tables 1 to 3 below.
  • Comparative Example 10 A comparative water-absorbent resin (10) was obtained according to the method described in Example 2-24 of International Publication WO2014 / 054656 (Patent Document 23). The resulting final product, comparative water-absorbent resin (10), was analyzed. The production conditions and analysis results are shown in Tables 1, 2, and 4 below.
  • the amount of the chelating agent in the hydrogel after the polymerization step in each of the Examples and Comparative Examples, and the amount of the chelating agent in the hydrogel after the gel pulverizing step are as follows: 97% to almost 100% of the amount of 1000 ppm added to the monomer remained. Therefore, substantially no decrease in the chelating agent was observed in the polymerization step or the gel pulverizing step.
  • the amount of the chelating agent in the water-absorbent resin or the comparative water-absorbent resin obtained by pulverization and the temperature of 180 ° C.
  • the heat treatment was performed for 40 minutes, and the amount of the chelating agent in the surface-crosslinked water-absorbent resin or the comparative water-absorbent resin was compared, but no difference was found between the two. Therefore, even when the surface crosslinking step was performed at 180 ° C., no decrease in the chelating agent was observed.
  • the production method according to the present invention increases the content of the chelating agent and also increases the L value of the initial coloring of the obtained water-absorbent resin (the same chelating agent improves the L value by one point). ). Also, from the comparison results of Comparative Example 2 and Comparative Example 5 in which the amount of the polymerization initiator added (0.04 mol%), the amount of the chelating agent added, and the gel particle diameter were the same, the solid content when dried was 80%. It can be seen that as the time for achieving the above becomes shorter, the residual ratio of the chelating agent is improved, and the L value of the initial coloring is increased. In the production method according to the present invention, it can be seen that the L value increases as the gel particle diameter is smaller and the time to achieve a solid content of 80% upon drying is faster.
  • Example 1 1000 ppm based on monomer; 0.0173 mol, in which the polymerization initiator and the amount added (0.04 mol%) were the same and the amount added of the chelating agent (DTPA) was changed. %), Example 9 (300 ppm based on the monomer; 0.0052 mol%), and Example 10 (50 ppm based on the monomer; 0.0009 mol%) show that the persulfate for the chelating agent was used. It can be seen that as the molar ratio increases from 2.3 to 7.7 and further to 46.3, the residual amount of the chelating agent in the water absorbent resin of the final product decreases from 50% to 39% and further to 30%. .
  • Example 2 (0.015 mol%; 942 ⁇ m) in which the chelating agent (DTPA) and its addition amount (0.0173 mol%) were the same, and the addition amount of the polymerization initiator and the gel particle diameter were changed. From the results of comparison with Comparative Example 2 (0.04 mol%; ⁇ 5000 ⁇ m), the molar ratio of the persulfate to the chelating agent and the gel particle diameter were reduced, so that the water absorption resin in the final product was reduced. It can be seen that the residual amount of the chelating agent is remarkably improved, and the YI values of the initial coloring and the coloring with the lapse of time are reduced, and in particular, the resistance to the coloring with the lapse of time is improved.
  • Comparative Example 8 has a smaller amount of the chelating agent added during the polymerization and a larger amount of the persulfate as the polymerization initiator than Example 2. Therefore, it can be seen that the residual ratio of the chelating agent decreases and the initial coloring (L value, YI value) deteriorates.
  • Example 18 To 100 parts by weight of the water-absorbent resin (1) obtained in Example 1, 1 part by weight of a 1% by weight DTPA ⁇ 5 sodium aqueous solution was added, and the inside thereof contained 501 ppm of a chelating agent, and further contained 100 ppm of a chelating agent on the surface. Water-absorbing resin (18) was obtained. Almost all of the chelating agent added later was contained near the surface of the water absorbent resin (18), and the content of the chelating agent in the water absorbent resin (18) was increased by about 100 ppm. The CRC and AAP (0.7 psi) of the water absorbent resin (18) were almost the same as those of the water absorbent resin (1) (decrease corresponding to 1% of added water).
  • Examples 19 to 21 In the same manner as in Example 18, for each of the water-absorbent resins (2) to (4) obtained in Examples 2 to 4, 1% by weight of a 1% by weight DTPA / 5 sodium aqueous solution was added to 100 parts by weight of the water-absorbent resin. Was added to obtain water-absorbing resins (19) to (21). Each of the water-absorbent resins (19) to (21) contained the same amount of the chelating agent as the water-absorbent resins (2) to (4), respectively, and further contained 100 ppm of the chelating agent on the surface.
  • the water-absorbent resin obtained by the production method of the present invention shows a high chelating agent residual ratio with respect to the chelating agent added before the drying step, A sufficient amount of the chelating agent remained in the water absorbent resin as the final product. Therefore, a chelating agent can be blended on the surface and inside of the particles of the water-absorbing resin, and due to the coloring resistance of the chelating agent, the water-absorbing resin as a final product exhibited a low YI value and exhibited good whiteness.
  • the water-absorbent resin produced by the production method of the present invention is useful for sanitary articles such as disposable diapers, sanitary napkins, and medical blood retention agents.
  • pet urine absorbents urine gelling agents for portable toilets and freshness preserving agents for fruits and vegetables, drip absorbents for meat and seafood, cooling agents, disposable warmers, gelling agents for batteries, water retaining agents for plants and soil, etc. It can also be used in various applications such as anti-condensation agents, water blocking agents and packing agents, and artificial snow.

Abstract

Selon la présente invention, la quantité ajoutée de persulfate, dans un amorceur de polymérisation provenant d'une étape de polymérisation précédant une étape de séchage, est réduite à la quantité totale de 0 à 0,04 % en moles (par rapport à un monomère pendant la polymérisation), et la grosseur des particules de gel d'un polymère de type gel contenant de l'eau, avant l'étape de séchage, et l'état de séchage, sont régulés, ce qui supprime la décomposition d'un agent chélatant dans l'étape de séchage.
PCT/JP2019/037091 2018-09-21 2019-09-20 Procédé de production d'une résine absorbant l'eau, contenant un agent chélatant WO2020059871A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
KR1020217011184A KR102562511B1 (ko) 2018-09-21 2019-09-20 킬레이트제를 포함하는 흡수성 수지의 제조 방법
CN201980061281.2A CN112714770B (zh) 2018-09-21 2019-09-20 含螯合剂的吸水性树脂的制造方法
JP2020549156A JP7064614B2 (ja) 2018-09-21 2019-09-20 キレート剤を含む吸水性樹脂の製造方法

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018-177808 2018-09-21
JP2018177808 2018-09-21

Publications (1)

Publication Number Publication Date
WO2020059871A1 true WO2020059871A1 (fr) 2020-03-26

Family

ID=69887307

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/037091 WO2020059871A1 (fr) 2018-09-21 2019-09-20 Procédé de production d'une résine absorbant l'eau, contenant un agent chélatant

Country Status (4)

Country Link
JP (1) JP7064614B2 (fr)
KR (1) KR102562511B1 (fr)
CN (1) CN112714770B (fr)
WO (1) WO2020059871A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022169227A1 (fr) * 2021-02-03 2022-08-11 주식회사 엘지화학 Procédé de préparation d'un polymère superabsorbant
JP7128978B1 (ja) 2022-03-30 2022-08-31 Ｓｄｐグローバル株式会社 吸水性樹脂組成物の製造方法、吸水性樹脂組成物、これを用いた吸収体、及び吸収性物品
WO2023276930A1 (fr) * 2021-06-28 2023-01-05 Ｓｄｐグローバル株式会社 Composition de résine absorbant l'eau, absorbant et article absorbant la comprenant chacun, et procédé de production de composition de résine absorbant l'eau

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006045498A (ja) * 2004-07-07 2006-02-16 Nippon Shokubai Co Ltd 吸水性樹脂組成物とその製造方法
JP2009520834A (ja) * 2005-12-22 2009-05-28 株式会社日本触媒 吸水性樹脂組成物およびその製造方法、吸収性物品
WO2009133664A1 (fr) * 2008-04-30 2009-11-05 三洋化成工業株式会社 Composition de résine, procédé de production d'une résine absorbant les liquides et film de résine absorbant les liquides
JP2010522255A (ja) * 2007-03-23 2010-07-01 エボニック ストックハウゼン，インコーポレイティド 高透過率高吸収性ポリマー組成物
JP2011178969A (ja) * 2010-03-04 2011-09-15 San-Dia Polymer Ltd 吸収性樹脂粒子及びこの製造方法
JP2012012482A (ja) * 2010-06-30 2012-01-19 Nippon Shokubai Co Ltd ポリアクリル酸アンモニウム塩系吸水性樹脂およびその製造方法

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2116035A1 (fr) 1991-09-09 1993-03-18 Fredric L. Buchholz Polymeres superabsorbants et methode de preparation
JP2912800B2 (ja) 1993-09-14 1999-06-28 株式会社ピーエフユー コピー防止付証明書発行装置
KR100468831B1 (ko) 1998-07-07 2005-03-16 삼성에스디아이 주식회사 플라즈마디스플레이패널및그제조방법
KR20000038407A (ko) 1998-12-07 2000-07-05 이기운 마이크로 로보트를 이용한 게임기
JP2003206381A (ja) 2002-01-15 2003-07-22 Sumitomo Seika Chem Co Ltd 吸水性樹脂の着色防止方法
JP3939988B2 (ja) 2002-01-16 2007-07-04 住友精化株式会社 吸水性樹脂の製造方法
EP1900755B1 (fr) 2005-07-04 2011-10-19 Sumitomo Seika Chemicals Co., Ltd. Procede de fabrication de resine absorbant l'eau
EP2112172B2 (fr) 2007-01-24 2018-10-17 Nippon Shokubai Co., Ltd. Polymère particulaire absorbant l'eau et son procédé de fabrication
SA08290402B1 (ar) 2007-07-04 2014-05-22 نيبون شوكوباي كو. ، ليمتد عامل دقائقي ماص للماء وطريقة لتصنيعه
CN102574100A (zh) 2009-09-30 2012-07-11 株式会社日本触媒 颗粒状吸水剂及其制造方法
EP2371869A1 (fr) 2010-03-30 2011-10-05 Evonik Stockhausen GmbH Procédé pour la production d'un polymère super-absorbant
KR102196888B1 (ko) 2012-10-01 2020-12-30 가부시키가이샤 닛폰 쇼쿠바이 다원 금속 화합물을 포함하는 분진 저감제, 다원 금속 화합물을 포함하는 흡수제 및 그의 제조 방법
SG11201602804SA (en) * 2013-10-09 2016-05-30 Nippon Catalytic Chem Ind Particulate Water-Absorbing Agent Containing Water-Absorbing Resin asMain Component and Method for Producing The Same
US9896529B2 (en) * 2014-03-03 2018-02-20 Nippon Shokubai Co., Ltd. Method for producing polyacrylic acid (salt)-based water-absorbable resin
JP5766344B1 (ja) 2014-07-11 2015-08-19 住友精化株式会社 吸水性樹脂及び吸収性物品
US11325990B2 (en) 2016-08-10 2022-05-10 Basf Se Method for the production of superabsorbers

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006045498A (ja) * 2004-07-07 2006-02-16 Nippon Shokubai Co Ltd 吸水性樹脂組成物とその製造方法
JP2009520834A (ja) * 2005-12-22 2009-05-28 株式会社日本触媒 吸水性樹脂組成物およびその製造方法、吸収性物品
JP2010522255A (ja) * 2007-03-23 2010-07-01 エボニック ストックハウゼン，インコーポレイティド 高透過率高吸収性ポリマー組成物
WO2009133664A1 (fr) * 2008-04-30 2009-11-05 三洋化成工業株式会社 Composition de résine, procédé de production d'une résine absorbant les liquides et film de résine absorbant les liquides
JP2011178969A (ja) * 2010-03-04 2011-09-15 San-Dia Polymer Ltd 吸収性樹脂粒子及びこの製造方法
JP2012012482A (ja) * 2010-06-30 2012-01-19 Nippon Shokubai Co Ltd ポリアクリル酸アンモニウム塩系吸水性樹脂およびその製造方法

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022169227A1 (fr) * 2021-02-03 2022-08-11 주식회사 엘지화학 Procédé de préparation d'un polymère superabsorbant
EP4166599A4 (fr) * 2021-02-03 2024-01-17 Lg Chemical Ltd Procédé de préparation d'un polymère superabsorbant
WO2023276930A1 (fr) * 2021-06-28 2023-01-05 Ｓｄｐグローバル株式会社 Composition de résine absorbant l'eau, absorbant et article absorbant la comprenant chacun, et procédé de production de composition de résine absorbant l'eau
WO2023276925A1 (fr) * 2021-06-28 2023-01-05 Ｓｄｐグローバル株式会社 Composition de résine absorbant l'eau, absorbeur et article absorbant obtenus à l'aide de celle-ci, et procédé de production d'une composition de résine absorbant l'eau
JP7128978B1 (ja) 2022-03-30 2022-08-31 Ｓｄｐグローバル株式会社 吸水性樹脂組成物の製造方法、吸水性樹脂組成物、これを用いた吸収体、及び吸収性物品
JP2023147658A (ja) * 2022-03-30 2023-10-13 Ｓｄｐグローバル株式会社 吸水性樹脂組成物の製造方法、吸水性樹脂組成物、これを用いた吸収体、及び吸収性物品

Also Published As

Publication number Publication date
JP7064614B2 (ja) 2022-05-10
CN112714770A (zh) 2021-04-27
CN112714770B (zh) 2023-03-28
JPWO2020059871A1 (ja) 2021-08-30
KR102562511B1 (ko) 2023-08-03
KR20210058928A (ko) 2021-05-24

Similar Documents

Publication Publication Date Title
JP5616437B2 (ja) ポリアクリル酸（塩）系吸水性樹脂粉末の製造方法
JP6457067B2 (ja) ポリアクリル酸（塩）系吸水性樹脂粉末及びその製造方法、並びにその評価方法
EP1903062B1 (fr) Unité d'affichage et son procédé de commande
JP6093751B2 (ja) ポリアクリル酸（塩）系吸水性樹脂粉末の製造方法及びポリアクリル酸（塩）系吸水性樹脂粉末
CN109608661B (zh) 凝胶粉碎装置、及聚丙烯酸(盐)系吸水性树脂粉末的制造方法、以及吸水性树脂粉末
JP5989913B2 (ja) ゲル粉砕装置、及びポリアクリル酸（塩）系吸水性樹脂粉末の製造方法、並びに吸水性樹脂粉末
JP6151790B2 (ja) 吸水性樹脂を主成分とする粒子状吸水剤及びその製造方法
JP7016798B2 (ja) 吸水剤の製造方法
KR102195097B1 (ko) 폴리아크릴산(염)계 흡수성 수지 및 그의 제조 방법
JP4805490B2 (ja) 吸水性樹脂の製造方法
JP5587348B2 (ja) 吸水性樹脂の製造方法
JP7064614B2 (ja) キレート剤を含む吸水性樹脂の製造方法
WO2020189539A1 (fr) Procédé de production d'un absorbant d'eau particulaire
JP2016112475A (ja) ポリ（メタ）アクリル酸塩系吸水性樹脂を主成分とする吸水剤及びその製造方法
WO2022163849A1 (fr) Procédé de fabrication d'une résine absorbant l'eau
JP2018065905A (ja) ポリアクリル酸（塩）系吸水性樹脂粉末の製造方法

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: 19862513

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2020549156

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 20217011184

Country of ref document: KR

Kind code of ref document: A

122 Ep: pct application non-entry in european phase

Ref document number: 19862513

Country of ref document: EP

Kind code of ref document: A1