WO2021049465A1 - 荷重下吸水量の向上方法、架橋重合体粒子の製造方法、及び、吸水性樹脂粒子の製造方法 - Google Patents

荷重下吸水量の向上方法、架橋重合体粒子の製造方法、及び、吸水性樹脂粒子の製造方法 Download PDF

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WO2021049465A1
WO2021049465A1 PCT/JP2020/033830 JP2020033830W WO2021049465A1 WO 2021049465 A1 WO2021049465 A1 WO 2021049465A1 JP 2020033830 W JP2020033830 W JP 2020033830W WO 2021049465 A1 WO2021049465 A1 WO 2021049465A1
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crosslinked polymer
particles
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mass
polymer particles
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English (en)
French (fr)
Japanese (ja)
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萌 西田
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Sumitomo Seika Chemicals Co Ltd
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Sumitomo Seika Chemicals Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C19/00—Other disintegrating devices or methods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
    • B07B1/28—Moving screens not otherwise provided for, e.g. swinging, reciprocating, rocking, tilting or wobbling screens
    • 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

Definitions

  • the present invention relates to a method for improving water absorption under load, a method for producing crosslinked polymer particles, and a method for producing water-absorbent resin particles.
  • an absorber containing water-absorbent resin particles has been used as an absorbent article for absorbing a liquid containing water as a main component (for example, urine) (see, for example, Patent Document 1 below).
  • the water-absorbent resin particles are obtained, for example, by crushing a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer to obtain crosslinked polymer particles, and then subjecting the crosslinked polymer particles to crosslinking. Obtainable.
  • the water-absorbent resin particles constituting the absorber are required to have an excellent water absorption amount.
  • a load is applied to the water-absorbent resin particles, and the water absorption amount of the water-absorbent resin particles in such a loaded state is improved. It is required to make it.
  • the present inventor has found that even water-absorbent resin particles having excellent water absorption performance (for example, CRC (Centrifuge Crosslink Polymer)) different from the water absorption amount under load may not be able to obtain a sufficient water absorption amount under load.
  • CRC Chiptrifuge Crosslink Polymer
  • One aspect of the present invention is a method for improving the amount of water absorption under load of water-absorbent resin particles obtained by cross-linking the cross-linked polymer particles, and has a structural unit derived from an ethylenically unsaturated monomer.
  • a method for improving water absorption under load which comprises a crushing step of obtaining crosslinked polymer particles satisfying the following (a) to (c) by crushing the crosslinked polymer.
  • A) The proportion of particles having a particle diameter of less than 500 ⁇ m in the crosslinked polymer particles is 50% by mass or more.
  • the proportion of particles having a particle diameter of less than 106 ⁇ m in the crosslinked polymer particles is 20% by mass or less.
  • the proportion of particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m in the crosslinked polymer particles is 40% by mass or less.
  • Another aspect of the present invention is a pulverization step of pulverizing a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer to obtain crosslinked polymer particles satisfying the following (a) to (c).
  • a method for producing crosslinked polymer particles (A) The proportion of particles having a particle diameter of less than 500 ⁇ m in the crosslinked polymer particles is 50% by mass or more. (B) The proportion of particles having a particle diameter of less than 106 ⁇ m in the crosslinked polymer particles is 20% by mass or less. (C) The proportion of particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m in the crosslinked polymer particles is 40% by mass or less.
  • Another aspect of the present invention provides a method for producing water-absorbent resin particles, which comprises a step of performing additional cross-linking on the cross-linked polymer particles obtained by the above-mentioned method for producing cross-linked polymer particles.
  • the method for producing crosslinked polymer particles, and the method for producing water-absorbent resin particles it is possible to improve the amount of water absorption under load of the water-absorbent resin particles, and the load can be improved. It is possible to obtain water-absorbent resin particles having an excellent amount of lower water absorption.
  • the particle size of the particles contained in the crosslinked polymer particles is classified after the crosslinked polymer is crushed to obtain the crosslinked polymer particles. It may be adjusted by particle size adjustment processing such as processing.
  • the present inventor has complicated the manufacturing process of the water-absorbent resin particles by adding the particle size adjusting treatment, and has an excellent amount of water absorption under load even if the particle size adjusting treatment is performed after pulverization. The idea was to obtain crosslinked polymer particles capable of obtaining water-absorbent resin particles having an excellent amount of water absorption under load by a simple method, paying attention to the fact that the particles may not be obtained.
  • crosslinked polymer particles crosslinked polymer particles satisfying the above-mentioned (a) to (c) that give water absorption under load are obtained in the pulverization step.
  • the amount of water absorption under load of the water-absorbent resin particles is improved by a simple method without performing particle size adjustment treatment after the pulverization step. It is possible to obtain water-absorbent resin particles having an excellent amount of water absorption under load by a simple method.
  • Water-soluble means that it exhibits a solubility in water of 5% by mass or more at 25 ° C.
  • the materials exemplified in the present specification may be used alone or in combination of two or more.
  • the content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.
  • “Saline” refers to a 0.9% by mass sodium chloride aqueous solution.
  • At least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof what are "content of (meth) acrylic acid compound” and “total mass of (meth) acrylic acid compound”? , Acrylic acid, acrylate, methacrylic acid and methacrylic acid total amount.
  • Room temperature means 25 ° C ⁇ 2 ° C.
  • the method for improving the amount of water absorption under load according to the present embodiment is a method for improving the amount of water absorption under load of the water-absorbent resin particles obtained by subjecting the crosslinked polymer particles to cross-linking.
  • the method for producing crosslinked polymer particles according to the present embodiment is a method for producing crosslinked polymer particles capable of obtaining water-absorbent resin particles by subjecting crosslinking.
  • the method for improving the amount of water absorbed under load and the method for producing crosslinked polymer particles according to the present embodiment are to pulverize a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer.
  • a pulverization step for obtaining crosslinked polymer particles (crushed product) satisfying the following (a) to (c) is provided.
  • the crosslinked polymer particles according to the present embodiment are crosslinked polymer particles from which water-absorbent resin particles can be obtained by performing additional cross-linking, and have a structural unit derived from an ethylenically unsaturated monomer. The following (a) to (c) are satisfied.
  • (A) The proportion of particles having a particle diameter of less than 500 ⁇ m in the crosslinked polymer particles is 50% by mass or more.
  • B The proportion of particles having a particle diameter of less than 106 ⁇ m in the crosslinked polymer particles is 20% by mass or less.
  • C The proportion of particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m in the crosslinked polymer particles is 40% by mass or less.
  • the crosslinked polymer particles according to the present embodiment or the crosslinked polymer particles obtained by the method for producing the crosslinked polymer particles according to the present embodiment are crosslinked. It is provided with a cross-linking step to be applied.
  • the crosslinked polymer particles according to the present embodiment and the method for producing the same, and the method for producing the water-absorbent resin particles according to the present embodiment, the water-absorbent resin particles It is possible to improve the amount of water absorption under load, and it is possible to obtain water-absorbent resin particles having an excellent amount of water absorption under load.
  • the reason why the amount of water absorption under load can be improved is not clear, but the present inventor speculates as follows.
  • the cause is not limited to the following contents. That is, when the crosslinked polymer is pulverized under inappropriate conditions, the crosslinked polymer particles are damaged and a sufficient amount of water absorption under a load cannot be obtained.
  • the crosslinked polymer is pulverized under appropriate conditions by adjusting the conditions of the pulverization treatment using the particle size of the particles constituting the crosslinked polymer particles obtained by the pulverization treatment as an index. Damage to the crosslinked polymer particles can be suppressed and the amount of water absorbed under load can be improved. In order to obtain an excellent amount of water absorption under load of the water-absorbent resin particles, it is desirable that an excessively large amount of particles does not exist, and therefore it is desirable that the proportion of particles having a particle diameter of less than 500 ⁇ m is large.
  • particles having a small diameter such as particles having a particle diameter of less than 106 ⁇ m and particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m may be obtained by reducing the diameter by pulverizing a large number of times in the pulverization step. Therefore, since such small-diameter particles (for example, the surface of the particles) may be excessively damaged, it is easy to improve the water absorption under load by reducing the number of small-diameter particles. Further, in order to improve the amount of water absorption under load, it is desirable that the cross-linking proceeds uniformly over the entire cross-linked polymer particles when the cross-linked polymer particles are subjected to additional cross-linking.
  • water absorption is performed without performing particle size adjustment treatment such as classification treatment after the pulverization step. It is possible to improve the water absorption amount of the sex resin particles under load by a simple method, and it is possible to obtain water-absorbent resin particles having an excellent water absorption amount under load by a simple method.
  • the crosslinked polymer having a structural unit derived from the ethylenically unsaturated monomer is pulverized to obtain crosslinked polymer particles satisfying the above-mentioned (a) to (c).
  • crosslinked polymer particles satisfying the above-mentioned (a) to (c) can be obtained by adjusting the type of the pulverizer, the pulverization conditions, and the like.
  • the crosslinked polymer can be crushed using a screen (net member, punching plate, etc.) having openings (through holes; mesh).
  • the present embodiment may be, for example, an embodiment in which the crosslinked polymer is pulverized while passing the crosslinked polymer through the screen in the pulverization step.
  • the particles constituting the crosslinked polymer particles can be obtained on the other side of the screen.
  • the particle size can be adjusted while crushing the crosslinked polymer, and particles having a diameter corresponding to the opening diameter of the opening of the screen can be obtained on the other side of the screen.
  • the opening of the screen has an opening diameter larger than the diameter of at least a part of the crosslinked polymer to be pulverized.
  • the opening diameter (hole diameter) of the screen opening may be, for example, 0.08 to 10 mm, 0.50 to 2.0 mm, or 0.75 to 1.5 mm.
  • the screen may be annular (for example, annular), plate-shaped, or the like.
  • the present embodiment may be, for example, an embodiment in which the crosslinked polymer is pulverized while passing the crosslinked polymer through the screen by applying a centrifugal force to the crosslinked polymer in the pulverization step.
  • the crosslinked polymer can be impact pulverized by colliding the crosslinked polymer with a screen or another member (for example, a rotating member described later) by centrifugal force.
  • the screen is cyclic, and in the pulverization step, the crosslinked polymer is subjected to centrifugal force (centrifugal force from the inner peripheral side to the outer peripheral side) on the inner peripheral side of the screen.
  • the crosslinked polymer is pulverized while passing the crosslinked polymer through a screen.
  • the particles constituting the crosslinked polymer particles can be obtained on the outer peripheral side of the screen.
  • the particle size can be adjusted while crushing the crosslinked polymer by impact pulverization, and particles having a diameter corresponding to the opening diameter of the opening of the screen can be obtained on the outer peripheral side of the screen.
  • the crusher used in the crushing step may have, for example, a sample table to which the crosslinked polymer is supplied and an annular screen surrounding the sample table.
  • the sample table may be rotatable, and centrifugal force may be applied to the crosslinked polymer by rotating the sample table.
  • centrifugal force can be applied to the crosslinked polymer by rotating the sample table around the central axis (axis orthogonal to the circumferential direction) of the annular screen.
  • the crusher may include a rotating member (for example, a blade member) that can rotate along the inner wall of the annular screen.
  • a rotating member for example, a blade member
  • the crosslinked polymer is easily impact-milled by colliding the crosslinked polymer with the rotating member by centrifugal force while rotating the rotating member.
  • the rotating member may be located near the inner wall of the screen. In this case, it is possible to apply a shearing force to the crosslinked polymer existing between the rotating member and the inner wall of the screen, and the crosslinked polymer can be easily crushed.
  • the rotating member may be a member that extends along the central axis of the annular screen.
  • the rotating member may be integrated with the sample table or may be separate from the sample table.
  • the rotating member may be rotatable with the sample table.
  • a plurality (for example, 6) of rotating members may be arranged at intervals on the outer peripheral portion of the sample table.
  • the rotation speed of each of the sample table and the rotating member may be, for example, 6000 to 18000 rpm.
  • a product name manufactured by Verder Scientific Co., Ltd .: ZM200; a product name manufactured by Fritsch Japan Co., Ltd .: P-14 rotor speed mill (Pulveristte 14) or the like can be used.
  • a crusher in which the particles that have passed through the screen are not further adjusted in particle size can be used.
  • the proportion of particles having a particle diameter of less than 500 ⁇ m in the crosslinked polymer particles according to the present embodiment is 50% by mass or more based on the total mass of the crosslinked polymer particles, and is in the following range. It's okay.
  • the proportion of particles with a particle diameter of less than 500 ⁇ m is more than 50% by mass, 55% by mass or more, 60% by mass or more, more than 60% by mass, 65% by mass or more, more than 65% by mass, or 67% by mass or more. It may be there.
  • the proportion of particles with a particle size of less than 500 ⁇ m is 90% by mass or less, less than 90% by mass, 85% by mass or less, 80% by mass or less, less than 80% by mass, 75% by mass or less, 70% by mass or less, or 70% by mass. May be less than. From these viewpoints, the proportion of particles having a particle diameter of less than 500 ⁇ m may be 50 to 90% by mass.
  • the proportion of particles having a particle diameter of less than 106 ⁇ m (more than 0 ⁇ m and less than 106 ⁇ m) in the crosslinked polymer particles according to the present embodiment is 20% by mass or less based on the total mass of the crosslinked polymer particles. Yes, it may be in the following range.
  • the proportion of particles with a particle size of less than 106 ⁇ m is less than 20% by mass, 17.5% by mass or less, 15% by mass or less, 12.5% by mass or less, 10% by mass or less, less than 10% by mass, and 9.9% by mass or less. , 9.8% by mass or less, 9.7% by mass or less, 9.6% by mass or less, or 9.5% by mass or less.
  • the proportion of particles with a particle size of less than 106 ⁇ m is 0% by mass or more, more than 0% by mass, 1% by mass or more, 2% by mass or more, 3% by mass or more, 4% by mass or more, 5% by mass or more, 6% by mass or more. , 7% by mass or more, 8% by mass or more, or 9% by mass or more. From these viewpoints, the proportion of particles having a particle diameter of less than 106 ⁇ m may be 0 to 20% by mass.
  • the proportion of particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m in the crosslinked polymer particles according to the present embodiment is the total of the crosslinked polymer particles from the viewpoint of improving the water absorption amount under load of the water-absorbent resin particles. It is 40% by mass or less based on the mass.
  • the proportion of particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m is less than 40% by mass, 35% by mass or less, and 35, based on the total mass of the crosslinked polymer particles, from the viewpoint of easily improving the amount of water absorption under load of the water-absorbent resin particles.
  • the proportion of particles with a particle size of 106 ⁇ m or more and less than 250 ⁇ m is 0% by mass or more, more than 0% by mass, 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or It may be 23% by mass or more. From these viewpoints, the proportion of particles having a particle diameter of 106 ⁇ m or more and less than 250 ⁇ m may be 0 to 40% by mass, and may be 20 to 40% by mass.
  • the proportion of particles having a particle diameter of 250 ⁇ m or more and less than 500 ⁇ m in the crosslinked polymer particles according to the present embodiment may be in the following range based on the total mass of the crosslinked polymer particles.
  • the proportion of particles having a particle diameter of 250 ⁇ m or more and less than 500 ⁇ m may be 50% by mass or less, less than 50% by mass, 45% by mass or less, 40% by mass or less, or 36% by mass or less.
  • the proportion of particles with a particle size of 250 ⁇ m or more and less than 500 ⁇ m is 0% by mass or more, more than 0% by mass, 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass. % Or more, 30% by mass or more, or 35% by mass or more. From these viewpoints, the proportion of particles having a particle diameter of 250 ⁇ m or more and less than 500 ⁇ m may be 0 to 50% by mass.
  • the proportion of particles having a particle diameter of 500 ⁇ m or more and less than 850 ⁇ m in the crosslinked polymer particles according to the present embodiment may be in the following range based on the total mass of the crosslinked polymer particles.
  • the proportion of particles having a particle diameter of 500 ⁇ m or more and less than 850 ⁇ m may be 50% by mass or less, less than 50% by mass, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less.
  • the proportion of particles with a particle diameter of 500 ⁇ m or more and less than 850 ⁇ m is 0% by mass or more, more than 0% by mass, 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass. % Or more, or 29% by mass or more. From these viewpoints, the proportion of particles having a particle diameter of 500 ⁇ m or more and less than 850 ⁇ m may be 0 to 50% by mass.
  • the proportion of particles having a particle diameter of 850 ⁇ m or more in the crosslinked polymer particles according to the present embodiment may be in the following range based on the total mass of the crosslinked polymer particles.
  • the proportion of particles having a particle diameter of 850 ⁇ m or more may be 10% by mass or less, less than 10% by mass, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, or 3% by mass or less. ..
  • the proportion of particles having a particle diameter of 850 ⁇ m or more may be 0% by mass or more, more than 0% by mass, 1% by mass or more, 2% by mass or more, or 2.5% by mass or more. From these viewpoints, the proportion of particles having a particle diameter of 850 ⁇ m or more may be 0 to 10% by mass.
  • the medium particle size of the crosslinked polymer particles according to this embodiment is preferably in the following range.
  • the medium particle size may be 250 ⁇ m or more, 280 ⁇ m or more, 300 ⁇ m or more, 330 ⁇ m or more, or 350 ⁇ m or more.
  • the medium particle size may be 600 ⁇ m or less, 550 ⁇ m or less, 500 ⁇ m or less, 450 ⁇ m or less, 400 ⁇ m or less, 380 ⁇ m or less, or 360 ⁇ m or less. From these viewpoints, the medium particle size may be 250 to 600 ⁇ m.
  • the medium particle size can be measured by the method described in Examples described later. For the medium particle size, the measured value at room temperature can be used.
  • the method for producing a crosslinked polymer includes a polymerization step of polymerizing a monomer composition containing an ethylenically unsaturated monomer.
  • a crosslinked polymer gel may be obtained by polymerizing a monomer composition containing an ethylenically unsaturated monomer.
  • the monomer composition may contain water, an organic solvent, and the like.
  • the monomer composition may be a monomer aqueous solution.
  • the polymerization method of the monomer composition include an aqueous solution polymerization method, a bulk polymerization method, a precipitation polymerization method and the like.
  • the aqueous solution polymerization method is preferable from the viewpoint that good water absorption performance (CRC, water absorption under load, etc.) can be easily obtained and the polymerization reaction can be easily controlled.
  • CRC water absorption performance
  • ethylenically unsaturated monomer a water-soluble ethylenically unsaturated monomer can be used.
  • the ethylenically unsaturated monomer include ⁇ , ⁇ -unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, maleic anhydride and fumaric acid, and carboxylic acid-based monomers such as salts thereof;
  • Nonionic monomers such as meta) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate;
  • N, N -Amino group-containing unsaturated monomers such as diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylamide, and quaternary products
  • Examples thereof include acids, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, and sulfonic acid-based monomers such as salts thereof.
  • the ethylenically unsaturated monomer can contain at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof.
  • the ethylenically unsaturated monomer may contain both (meth) acrylic acid and a salt of (meth) acrylic acid.
  • salts of ⁇ , ⁇ -unsaturated carboxylic acid include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, etc.) and the like.
  • the ethylenically unsaturated monomer having an acid group may have an acid group neutralized in advance with an alkaline neutralizer.
  • alkaline neutralizing agent include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide and potassium carbonate; ammonia and the like.
  • the alkaline neutralizer may be used in the form of an aqueous solution in order to simplify the neutralization operation.
  • the acid group may be neutralized before the polymerization of the ethylenically unsaturated monomer as a raw material, or during or after the polymerization.
  • the degree of neutralization of the ethylenically unsaturated monomer by the alkaline neutralizing agent is from the viewpoint that good water absorption performance (CRC, water absorption under load, etc.) can be easily obtained by increasing the osmotic pressure, and in excess alkalinity. From the viewpoint of suppressing defects caused by the presence of the Japanese agent, 10 to 100 mol%, 30 to 90 mol%, 40 to 85 mol%, or 50 to 80 mol% is preferable.
  • the "neutralization degree” is the neutralization degree for all the acid groups of the ethylenically unsaturated monomer.
  • the content of the (meth) acrylic acid compound is preferably in the following range based on the total mass of the monomer composition.
  • the content of the (meth) acrylic acid compound is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more from the viewpoint of easily increasing productivity. Is preferable.
  • the content of the (meth) acrylic acid compound is 60% by mass or less, 55% by mass or less, 50% by mass or less, less than 50% by mass, 45% by mass from the viewpoint of easily improving the water absorption performance (CRC, water absorption under load, etc.). % Or less, or 40% by mass or less is preferable. From these viewpoints, the content of the (meth) acrylic acid compound is preferably 10 to 60% by mass.
  • the content of the (meth) acrylic acid compound is the total amount of the monomers contained in the monomer composition and / or the total amount of the ethylenically unsaturated monomer contained in the monomer composition. The following range is preferable with reference to.
  • the content of the (meth) acrylic acid compound is preferably 50 mol% or more, 70 mol% or more, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more.
  • the monomer contained in the monomer composition and / or the ethylenically unsaturated monomer contained in the monomer composition is substantially composed of a (meth) acrylic acid compound (substantially).
  • 100 mol% of the monomer contained in the monomer composition and / or the ethylenically unsaturated monomer contained in the monomer composition is a (meth) acrylic acid compound). It may be.
  • the monomer composition may contain a polymerization initiator.
  • the polymerization of the monomer contained in the monomer composition may be started by adding a polymerization initiator to the monomer composition and, if necessary, heating, irradiating with light or the like.
  • the polymerization initiator include a photopolymerization initiator and a radical polymerization initiator, and a water-soluble radical polymerization initiator is preferable.
  • the polymerization initiator preferably contains at least one selected from the group consisting of azo compounds and peroxides from the viewpoint of easily enhancing water absorption performance (CRC, water absorption under load, etc.).
  • Examples of the azo compound include 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride and 2,2'-azobis ⁇ 2- [N- (4-chlorophenyl) amidino] propane ⁇ dihydrochloride.
  • the azo compounds are 2,2'-azobis (2-methylpropionamide) dihydrochloride and 2,2'-azobis (2) from the viewpoint that good water absorption performance (CRC, water absorption under load, etc.) can be easily obtained.
  • Peroxides include persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl. Examples thereof include organic peroxides such as peroxyacetate, t-butylperoxyisobutyrate, and t-butylperoxypivalate.
  • the peroxide preferably contains at least one selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate from the viewpoint of easily obtaining good water absorption performance (CRC, water absorption under load, etc.). ..
  • the content of the polymerization initiator is preferably in the following range with respect to 1 mol of the ethylenically unsaturated monomer (for example, (meth) acrylic acid compound).
  • the content of the polymerization initiator is 0.001 mmol or more, 0.003 mmol or more, 0.015 from the viewpoint of easily improving the water absorption performance (CRC, water absorption under load, etc.) and shortening the polymerization reaction time. It is preferably mmol or more, 0.03 mmol or more, 0.06 mmol or more, 0.08 mmol or more, or 0.1 mmol or more.
  • the content of the polymerization initiator is 5 mmol or less, 4 mmol or less, 2 mmol or less, 1 from the viewpoint of easily improving the water absorption performance (CRC, water absorption under load, etc.) and easily avoiding a rapid polymerization reaction. It is preferably mmol or less, 0.5 mmol or less, 0.3 mmol or less, 0.25 mmol or less, 0.2 mmol or less, or 0.15 mmol or less. From these viewpoints, the content of the polymerization initiator is preferably 0.001 to 5 mmol.
  • the monomer composition may contain a reducing agent.
  • the reducing agent include sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, L-ascorbic acid and the like.
  • a polymerization initiator and a reducing agent may be used in combination.
  • the monomer composition may contain an oxidizing agent.
  • the oxidizing agent include hydrogen peroxide, sodium perborate, perphosphoric acid and salts thereof, potassium permanganate and the like.
  • the monomer composition may contain an internal cross-linking agent.
  • the obtained cross-linked polymer can have a cross-linked structure by the internal cross-linking agent in addition to the self-cross-linking structure by the polymerization reaction as the internal cross-linking structure.
  • Examples of the internal cross-linking agent include compounds having two or more reactive functional groups (for example, polymerizable unsaturated groups).
  • Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as (poly) ethylene glycol, (poly) propylene glycol, trimethylolpropane, glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin.
  • Unsaturated polyesters obtained by reacting the above-mentioned polyol with an unsaturated acid (maleic acid, fumaric acid, etc.); (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin Glycidyl group-containing compounds such as diglycidyl ether and glycidyl (meth) acrylate; bisacrylamides such as N, N'-methylenebis (meth) acrylamide; di or tri (meth) obtained by reacting polyepoxide with (meth) acrylic acid.
  • unsaturated acid maleic acid, fumaric acid, etc.
  • the internal cross-linking agent has water absorption performance (CRC, water absorption under load, etc.).
  • It is selected from the group consisting of (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether from the viewpoint of being easy to increase and having excellent reactivity at low temperature. It is preferable to contain at least one kind.
  • the content of the internal cross-linking agent is preferably in the following range with respect to 1 mol of the ethylenically unsaturated monomer (for example, (meth) acrylic acid compound).
  • the content of the internal cross-linking agent is 0.0005 mmol or more, 0.001 mmol or more, 0.002 mmol or more, 0.005 mmol from the viewpoint that good water absorption performance (CRC, water absorption under load, etc.) can be easily obtained.
  • CRC water absorption under load, etc.
  • 0.01 mmol or more, 0.015 mmol or more, 0.02 mmol or more, or 0.025 mmol or more is preferable.
  • the content of the internal cross-linking agent is 0.3 mmol or less, 0.25 mmol or less, 0.2 mmol or less, 0.18 mmol from the viewpoint that good water absorption performance (CRC, water absorption under load, etc.) can be easily obtained.
  • the monomer composition may contain additives such as a chain transfer agent, a thickener, and an inorganic filler as components different from the above-mentioned components.
  • a chain transfer agent include thiols, thiol acids, secondary alcohols, hypophosphorous acid, phosphorous acid, achlorine and the like.
  • the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyethylene glycol, polyacrylic acid, neutralized polyacrylic acid, polyacrylamide and the like.
  • the inorganic filler include metal oxides, ceramics, and viscous minerals.
  • a polymerization method for aqueous solution polymerization As a polymerization method for aqueous solution polymerization, a static polymerization method in which the monomer composition is polymerized without stirring (for example, a static state); a stirring polymerization method in which the monomer composition is polymerized while stirring in a reaction apparatus. And so on.
  • a static polymerization method when the polymerization is completed, a single block-shaped gel occupying substantially the same volume as the monomer composition present in the reaction vessel is obtained.
  • the form of polymerization may be batch, semi-continuous, continuous, or the like.
  • the polymerization reaction can be carried out while continuously supplying the monomer composition to the continuous polymerization apparatus to continuously obtain a gel.
  • the polymerization temperature varies depending on the polymerization initiator used, but from the viewpoint of rapidly advancing the polymerization, increasing the productivity by shortening the polymerization time, removing the heat of polymerization, and facilitating the smooth reaction, 0 to 0 to It is preferably 130 ° C. or 10 to 110 ° C.
  • the polymerization time is appropriately set depending on the type and amount of the polymerization initiator used, the reaction temperature, and the like, but is preferably 1 to 200 minutes or 5 to 100 minutes.
  • the method for producing the crosslinked polymer may include a coarse crushing step and a drying step after the polymerization step.
  • the coarse crushing step is, for example, a step of coarsely crushing the crosslinked polymer (for example, a crosslinked polymer gel) obtained in the polymerization step to obtain a coarsely crushed product (for example, a gel coarse crushed product).
  • a kneader pressurized kneader, double-armed kneader, etc.
  • a meat chopper, a cutter mill, a pharma mill, or the like can be used.
  • the drying step is a step of drying the crushed product obtained in the crushing step to obtain a dried product.
  • a dried product for example, a gel dried product
  • the drying method may be natural drying, heat drying, vacuum drying or the like.
  • the drying temperature is, for example, 70 to 250 ° C.
  • the crosslinked polymer particles according to the present embodiment include a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer (for example, a (meth) acrylic acid compound). ..
  • the crosslinked polymer particles according to the present embodiment include a gel stabilizer, a metal chelating agent (ethylenediamine tetraacetic acid and its salt, diethylenetriamine 5 acetic acid and its salt (for example, diethylenetriamine 5 sodium acetate), etc.), and a fluidity improver (lubricant).
  • Other components such as may be further contained.
  • Other components may be located inside, on the surface, or both of the crosslinked polymers.
  • the crosslinked polymer particles according to the present embodiment may contain inorganic particles arranged on the surface of the crosslinked polymer.
  • the inorganic particles can be arranged on the surface of the crosslinked polymer.
  • the inorganic particles include silica particles such as amorphous silica.
  • the water-absorbent resin particles according to the present embodiment can be obtained by cross-linking the crosslinked polymer particles obtained in the pulverization step (crosslinking step).
  • the cross-linking may be surface cross-linking to the cross-linked polymer particles.
  • the cross-linking can be performed, for example, by reacting a cross-linking agent (for example, a surface cross-linking agent) with the cross-linked polymer particles.
  • the cross-linking density of the cross-linked polymer particles (for example, the cross-linking density near the surface of the cross-linked polymer particles) is increased, so that the water absorption performance (CRC, water absorption under load, water absorption rate, etc.) ) Is easy to increase.
  • the amount of the cross-linking agent used may be adjusted in order to adjust the CRC of the water-absorbent resin particles equally.
  • cross-linking agent examples include compounds containing two or more functional groups (reactive functional groups) having reactivity with functional groups derived from ethylenically unsaturated monomers.
  • examples of the cross-linking agent include polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene glycol diglycidyl ether, Polyglycidyl compounds such as (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, (poly) glycerol polyglycidyl ether; epichlorohydrin, epibromhydrin, ⁇ -methylepicrolhydrin, etc.
  • Haloepoxy compounds compounds having two or more reactive functional groups such as isocyanate compounds (2,4-tolylene diisocyanate, hexamethylene diisocyanate, etc.); 3-methyl-3-oxetane methanol, 3-ethyl-3-oxetane Oxetane compounds such as methanol, 3-butyl-3-oxetane methanol, 3-methyl-3-oxetane ethanol, 3-ethyl-3-oxetane ethanol, 3-butyl-3-oxetane ethanol; 1,2-ethylenebisoxazoline and the like.
  • the water-absorbent resin particles according to the present embodiment have a gel stabilizer on the surface thereof; a metal chelating agent (ethylenediaminetetraacetic acid and its salt thereof, diethylenetriamine-5 acetic acid and its salt (for example, diethylenetriamine-5 sodium acetate), etc.); It may contain inorganic particles of an agent (lubricant).
  • a metal chelating agent ethylenediaminetetraacetic acid and its salt thereof, diethylenetriamine-5 acetic acid and its salt (for example, diethylenetriamine-5 sodium acetate), etc.
  • the inorganic particles can be arranged on the surface of the post-crosslinked particles.
  • the inorganic particles include silica particles such as amorphous silica.
  • the water-absorbent resin particles according to the present embodiment can retain water and can absorb body fluids such as urine, sweat, and blood (for example, menstrual blood).
  • the water-absorbent resin particles according to the present embodiment can be used as a constituent component of the absorber.
  • This embodiment can be used in the fields of, for example, sanitary materials such as disposable diapers and sanitary products; agricultural and horticultural materials such as water retention agents and soil conditioners; and industrial materials such as water stop agents and dew condensation inhibitors.
  • the CRC of the water-absorbent resin particles according to the present embodiment is 10 g / g or more, 15 g / g or more, 20 g / g or more, 25 g / g or more, 30 g / g or more, 32 g / g or more, or 34 g / g or more. It may be there.
  • the CRC of the water-absorbent resin particles may be 60 g / g or less, 55 g / g or less, 50 g / g or less, 45 g / g or less, 40 g / g or less, or 35 g / g or less.
  • the CRC of the water-absorbent resin particles may be 10 to 60 g / g.
  • CRC is an abbreviation for Centrifuge Retention Capacity (centrifuge holding capacity).
  • the CRC of the water-absorbent resin particles can be measured by the method described in Examples described later with reference to the EDANA method (NWSP 241.0.R2 (15), page.769-778).
  • NWSP 241.0.R2 15
  • a water absorption ratio when a non-woven bag containing 0.2 g of water-absorbent resin particles in a dry state is immersed in 1000 g of physiological saline for 30 minutes and then centrifuged using a centrifuge to drain water. Obtainable.
  • the CRC of the water-absorbent resin particles a measured value at room temperature can be used.
  • the method for improving the water absorption under load may include the above-mentioned cross-linking step and a measurement step for measuring the water absorption under load of the water-absorbent resin particles after the crushing step.
  • the amount of water absorption of the water-absorbent resin particles under load is preferably 21 mL / g or more, 21.5 mL / g or more, or 22 mL / g or more.
  • the amount of water absorption of the water-absorbent resin particles under load is preferably 35 mL / g or less, or 30 mL / g or less.
  • the amount of water absorption under load can be measured by the method described in Examples described later.
  • As the water absorption amount of the water-absorbent resin particles under load a measured value at room temperature can be used.
  • the absorber according to the present embodiment contains the water-absorbent resin particles according to the present embodiment.
  • the absorber according to the present embodiment may contain a fibrous substance, for example, a mixture containing water-absorbent resin particles and the fibrous substance.
  • the structure of the absorber may be, for example, a structure in which the water-absorbent resin particles and the fibrous material are uniformly mixed, and the water-absorbent resin particles are sandwiched between the fibrous material formed in a sheet or layer. It may be a configuration or another configuration.
  • the fibrous material examples include finely pulverized wood pulp; cotton; cotton linter; rayon; cellulosic fibers such as cellulose acetate; synthetic fibers such as polyamide, polyester and polyolefin; and a mixture of these fibers.
  • hydrophilic fibers can be used as the fibrous material.
  • the fibers may be adhered to each other by adding an adhesive binder to the fibrous material.
  • the adhesive binder include heat-sealing synthetic fibers, hot melt adhesives, and adhesive emulsions.
  • the heat-bondable synthetic fiber examples include a total fusion type binder such as polyethylene, polypropylene, and an ethylene-propylene copolymer; a non-total fusion type binder having a side-by-side or core-sheath structure of polypropylene and polyethylene.
  • a total fusion type binder such as polyethylene, polypropylene, and an ethylene-propylene copolymer
  • non-total fusion type binder having a side-by-side or core-sheath structure of polypropylene and polyethylene.
  • hot melt adhesive examples include ethylene-vinyl acetate copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.
  • a mixture of a base polymer such as amorphous polypropylene and a tackifier, a plasticizer, an antioxidant and the like.
  • Examples of the adhesive emulsion include polymers of at least one monomer selected from the group consisting of methyl methacrylate, styrene, acrylonitrile, 2-ethylhexyl acrylate, butyl acrylate, butadiene, ethylene, and vinyl acetate.
  • the absorber according to the present embodiment may contain inorganic particles (for example, amorphous silica), a deodorant, an antibacterial agent, a pigment, a dye, a fragrance, an adhesive and the like.
  • inorganic particles for example, amorphous silica
  • the absorber may contain inorganic particles in addition to the inorganic particles in the water-absorbent resin particles.
  • the shape of the absorber according to this embodiment may be, for example, a sheet shape.
  • the thickness of the absorber (for example, the thickness of the sheet-shaped absorber) may be 0.1 to 20 mm or 0.3 to 15 mm.
  • the content of the water-absorbent resin particles in the absorber is 2 to 95% by mass, 10 to 80% by mass, or 20 to 20 to 95% by mass with respect to the total of the water-absorbent resin particles and the fibrous material from the viewpoint of easily obtaining sufficient absorption characteristics. It may be 60% by mass.
  • the content of the water-absorbent resin particles in the absorber is preferably 100 to 1000 g, 150 to 800 g, or 200 to 700 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient absorption characteristics.
  • the content of the fibrous material in the absorber is preferably 50 to 800 g, 100 to 600 g, or 150 to 500 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient absorption characteristics.
  • the absorbent article according to the present embodiment includes an absorber according to the present embodiment.
  • a core wrap that retains the shape of the absorber and prevents the constituent member of the absorber from falling off or flowing; Liquid permeable sheet to be arranged; Examples thereof include a liquid permeable sheet arranged on the outermost side opposite to the side on which the liquid to be absorbed enters.
  • absorbent articles include diapers (for example, paper diapers), toilet training pants, incontinence pads, sanitary materials (sanitary napkins, tampons, etc.), sweat pads, pet sheets, toilet members, animal excrement treatment materials, and the like. ..
  • FIG. 1 is a cross-sectional view showing an example of an absorbent article.
  • the absorbent article 100 shown in FIG. 1 includes an absorbent body 10, core wraps 20a and 20b, a liquid permeable sheet 30, and a liquid permeable sheet 40.
  • the liquid permeable sheet 40, the core wrap 20b, the absorbent body 10, the core wrap 20a, and the liquid permeable sheet 30 are laminated in this order.
  • the absorber 10 has a water-absorbent resin particle 10a and a fiber layer 10b containing a fibrous material.
  • the water-absorbent resin particles 10a are dispersed in the fiber layer 10b.
  • the core wrap 20a is arranged on one side of the absorber 10 (upper side of the absorber 10 in FIG. 1) in contact with the absorber 10.
  • the core wrap 20b is arranged on the other side of the absorber 10 (lower side of the absorber 10 in FIG. 1) in contact with the absorber 10.
  • the absorber 10 is arranged between the core wrap 20a and the core wrap 20b.
  • Examples of the core wraps 20a and 20b include tissues, non-woven fabrics, woven fabrics, synthetic resin films having liquid permeation holes, net-like sheets having a mesh, and the like.
  • the core wrap 20a and the core wrap 20b have, for example, a main surface having the same size as the absorber 10.
  • the liquid permeable sheet 30 is arranged on the outermost side on the side where the liquid to be absorbed enters.
  • the liquid permeable sheet 30 is arranged on the core wrap 20a in contact with the core wrap 20a.
  • Examples of the liquid permeable sheet 30 include non-woven fabrics made of synthetic resins such as polyethylene, polypropylene, polyester and polyamide, and porous sheets.
  • the liquid permeable sheet 40 is arranged on the outermost side of the absorbent article 100 on the opposite side of the liquid permeable sheet 30.
  • the liquid impermeable sheet 40 is arranged under the core wrap 20b in contact with the core wrap 20b.
  • liquid impermeable sheet 40 examples include a sheet made of a synthetic resin such as polyethylene, polypropylene, and polyvinyl chloride, and a sheet made of a composite material of these synthetic resins and a non-woven fabric.
  • the liquid permeable sheet 30 and the liquid permeable sheet 40 have, for example, a main surface wider than the main surface of the absorber 10, and the outer edges of the liquid permeable sheet 30 and the liquid permeable sheet 40 are It extends around the absorber 10 and the core wraps 20a, 20b.
  • the magnitude relationship between the absorbent body 10, the core wraps 20a and 20b, the liquid permeable sheet 30, and the liquid permeable sheet 40 is not particularly limited, and is appropriately adjusted according to the use of the absorbent article and the like. Further, the method of retaining the shape of the absorber 10 using the core wraps 20a and 20b is not particularly limited, and as shown in FIG. 1, the absorber may be wrapped by a plurality of core wraps, and the absorber is wrapped by one core wrap. But it may be.
  • the absorber may be adhered to the top sheet.
  • a hot melt adhesive is applied to the top sheet at predetermined intervals in a striped shape, a spiral shape, etc. in the width direction and adhered; starch, carboxymethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, etc. Examples thereof include a method of adhering using a water-soluble binder such as a water-soluble polymer.
  • a method of adhering by heat-sealing of the heat-sealing synthetic fibers may be adopted.
  • the present embodiment it is possible to provide a liquid absorbing method using the water-absorbent resin particles, the absorber or the absorbent article according to the present embodiment.
  • the liquid absorbing method according to the present embodiment includes a step of bringing the liquid to be absorbed into contact with the water-absorbent resin particles, the absorber or the absorbent article according to the present embodiment.
  • the present embodiment it is possible to provide a method for producing an absorber using the above-mentioned water-absorbent resin particles.
  • the method for producing an absorber according to the present embodiment includes a process for producing water-absorbent resin particles for obtaining the above-mentioned water-absorbent resin particles.
  • the method for producing an absorber according to the present embodiment may include a step of mixing the water-absorbent resin particles and the fibrous material after the step of producing the water-absorbent resin particles.
  • the method for producing an absorbent article according to the present embodiment includes an absorber manufacturing step for obtaining an absorber by the above-mentioned method for manufacturing an absorber.
  • the method for producing an absorbent article according to the present embodiment may include a step of obtaining an absorbent article by using the absorber and other constituent members of the absorbent article after the absorbent body manufacturing step. For example, an absorbent article is obtained by laminating the absorber and other constituent members of the absorbent article with each other.
  • Partial neutralization solution of sodium acrylate (monomer used for polymerization, monomer concentration: 45% by mass, neutralization rate of sodium acrylate: 75 mol%) 340.0 g, ethylene glycol diglycidyl ether 0.0077 g (inside) A cross-linking agent (0.044 mmol) and 59.0 g of ion-exchanged water were added, and then the mixture was uniformly mixed by rotating the stirrer to obtain a mixture. Then, the upper part of the stainless steel vat was covered with a polyethylene film. After adjusting the temperature of the mixture in the stainless steel pad to 25 ° C., the amount of dissolved oxygen was adjusted to 0.1 ppm or less by substituting nitrogen in the mixture.
  • the entire amount of the gel was taken out from the container, and then cut in a grid pattern at 5 cm intervals.
  • the entire amount of the cut post-polymerization gel was sequentially put into a meat chopper (model number: 12VR-750SDX, manufactured by Kiren Royal Co., Ltd.), and the post-polymerization gel was coarsely crushed.
  • the diameter of the hole (circular) of the plate located at the outlet of the meat chopper was 6.4 mm, and the density of the holes was 40 holes / 36.30 cm 2 .
  • Rough crushing was performed until no crushed material (coarse crushed gel, hydrogel crushed material) came out from the plate of the meat chopper.
  • the pyroclastic material was dried with hot air at 180 ° C. for 30 minutes to obtain a dried product (crosslinked polymer dried product).
  • Example 1 A crushed material was obtained by the same method as in Example 1. Next, 20 g of the pyroclastic material was pulverized for 12 seconds using a small crusher (Osaka Chemical Co., Ltd., product name: Wonder Blender WB-1) to obtain crosslinked polymer particles. The particle size distribution and medium particle size of the crosslinked polymer particles were measured by the procedure described later. Then, after performing additional cross-linking by the same method as in Example 1, 4.2 g of water-absorbent resin particles was obtained by passing the mixture through a mesh of 850 ⁇ m.
  • a small crusher Osaka Chemical Co., Ltd., product name: Wonder Blender WB-1
  • Crosslinked polymer particles were produced by the same method as in Comparative Example 1 to obtain crosslinked polymer particles 1.
  • the crosslinked polymer particles 1 were classified with a sieve having an opening of 850 ⁇ m, 500 ⁇ m, 250 ⁇ m, and 106 ⁇ m, and a saucer.
  • Crosslinked polymer particles 2 were obtained by remixing the classified particles in a required amount so that the particle size distribution was similar to that of the particles of Example 1.
  • the particle size distribution and the medium particle size of the crosslinked polymer particles 2 were measured by the procedure described later. Then, after performing additional cross-linking by the same method as in Example 1, 4.3 g of water-absorbent resin particles was obtained by passing the mixture through a mesh of 850 ⁇ m.
  • ⁇ Particle size distribution> Using a continuous fully automatic sonic vibration type sieving measuring instrument (Robot Shifter RPS-205, manufactured by Seishin Enterprise Co., Ltd.), crosslink with JIS standard 850 ⁇ m, 710 ⁇ m, 600 ⁇ m, 500 ⁇ m, 300 ⁇ m, 250 ⁇ m and 106 ⁇ m sieves and a saucer. The particle size distribution of 5 g of the polymer particles was measured.
  • a non-woven fabric with a size of 60 mm x 170 mm (product name: Heat Pack MWA-18, manufactured by Nippon Paper Papylia Co., Ltd.) was folded in half in the longitudinal direction to adjust the size to 60 mm x 85 mm.
  • a 60 mm ⁇ 85 mm non-woven fabric bag was produced by crimping the non-woven fabrics to each other on both sides extending in the longitudinal direction with a heat seal (a crimped portion having a width of 5 mm was formed on both sides along the longitudinal direction).
  • 0.2 g of the above-mentioned water-absorbent resin particles were contained in the non-woven fabric bag. Then, the non-woven fabric bag was closed by crimping the remaining one side extending in the lateral direction with a heat seal.
  • the entire non-woven fabric bag was completely moistened by floating the non-woven fabric bag on 1000 g of physiological saline contained in a stainless steel vat (240 mm ⁇ 320 mm ⁇ 45 mm) without folding the non-woven fabric bag.
  • a stainless steel vat 240 mm ⁇ 320 mm ⁇ 45 mm
  • the non-woven fabric bag was taken out from the physiological saline solution. Then, the non-woven fabric bag was put in a centrifuge (manufactured by Kokusan Co., Ltd., model number: H-122). After the centrifugal force in the centrifuge reached 250 G, the non-woven fabric bag was dehydrated for 3 minutes. After dehydration, it was weighed mass M a nonwoven bag containing the mass of gel. Subjecting the above procedure similar relative woven bags without accommodating the water-absorbent resin particles, the mass was measured M b of the nonwoven fabric bag.
  • the water absorption amount (room temperature) of the physiological saline under the load (pressurization) of the water-absorbent resin particles was measured using the measuring device Y shown in FIG.
  • the measuring device Y is composed of a burette unit 61, a conduit 62, a measuring table 63, and a measuring unit 64 placed on the measuring table 63.
  • the burette portion 61 has a burette 61a extending in the vertical direction, a rubber stopper 61b arranged at the upper end of the burette 61a, a cock 61c arranged at the lower end of the burette 61a, and one end extending into the burette 61a in the vicinity of the cock 61c.
  • the conduit 62 has an air introduction pipe 61d and a cock 61e arranged on the other end side of the air introduction pipe 61d.
  • the conduit 62 is attached between the burette portion 61 and the measuring table 63.
  • the inner diameter of the conduit 62 is 6 mm.
  • a hole having a diameter of 2 mm is formed in the central portion of the measuring table 63, and the conduit 62 is connected to the hole.
  • the measuring unit 64 has a cylinder 64a (made of acrylic resin (plexiglass)), a nylon mesh 64b adhered to the bottom of the cylinder 64a, and a weight 64c.
  • the inner diameter of the cylinder 64a is 20 mm.
  • the opening of the nylon mesh 64b is 75 ⁇ m (200 mesh).
  • the water-absorbent resin particles 65 to be measured are uniformly sprinkled on the nylon mesh 64b.
  • the diameter of the weight 64c is 19 mm, and the mass of the weight 64c is 119.6 g.
  • the weight 64c is placed on the water-absorbent resin particles 65, and a load of 4.14 kPa can be applied to the water-absorbent resin particles 65.
  • the weight 64c was placed and the measurement was started. Since the same volume of air as the physiological saline absorbed by the water-absorbent resin particles 65 is quickly and smoothly supplied to the inside of the burette 61a from the air introduction pipe, the water level of the physiological saline inside the burette 61a is reduced. However, the amount of physiological saline absorbed by the water-absorbent resin particles 65 is obtained.
  • the scale of the burette 61a is engraved from top to bottom in increments of 0 mL to 0.5 mL, and the scale Va of the burette 61a before the start of water absorption and the burette 61a 60 minutes after the start of water absorption are used as the water level of the physiological saline.
  • 10 Absorbent, 10a, 65 ... Water-absorbent resin particles, 10b ... Fiber layer, 20a, 20b ... Core wrap, 30 ... Liquid permeable sheet, 40 ... Liquid permeable sheet, 61 ... Burette part, 61a ... Burette, 61b ... Rubber stopper, 61c, 61e ... Cock, 61d ... Air introduction pipe, 62 ... Conduit, 63 ... Measuring table, 64 ... Measuring unit, 64a ... Cylindrical, 64b ... Nylon mesh, 64c ... Weight, 100 ... Absorbent article, Y ...measuring device.

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PCT/JP2020/033830 2019-09-09 2020-09-07 荷重下吸水量の向上方法、架橋重合体粒子の製造方法、及び、吸水性樹脂粒子の製造方法 Ceased WO2021049465A1 (ja)

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Citations (6)

* Cited by examiner, † Cited by third party
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