WO2021131898A1 - 吸水性樹脂粒子の製造方法及び重合体粒子の製造方法 - Google Patents

吸水性樹脂粒子の製造方法及び重合体粒子の製造方法 Download PDF

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WO2021131898A1
WO2021131898A1 PCT/JP2020/046732 JP2020046732W WO2021131898A1 WO 2021131898 A1 WO2021131898 A1 WO 2021131898A1 JP 2020046732 W JP2020046732 W JP 2020046732W WO 2021131898 A1 WO2021131898 A1 WO 2021131898A1
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particle group
polymer particle
mass
sieve
surface cross
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PCT/JP2020/046732
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English (en)
French (fr)
Japanese (ja)
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志保 岡澤
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住友精化株式会社
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating

Definitions

  • the present invention relates to a method for producing water-absorbent resin particles and a method for producing polymer particles.
  • an absorber containing water-absorbent resin particles has been used as an absorbent article for absorbing a liquid (for example, urine) containing water as a main component.
  • the water-absorbent resin particles in the absorber are required to have excellent liquid diffusivity in addition to having a high water absorption amount.
  • the liquid diffusibility generally tends to decrease as the proportion of fine powder in the water-absorbent resin particles increases. That is, the fine powder in the water-absorbent resin particles tends to block the path for the liquid to diffuse when swollen, and tends to cause so-called "gel blocking".
  • the fine powder is removed as described above, the number of water-absorbent resin particles that become the product decreases. Therefore, in order not to deteriorate the productivity, it is required to utilize the fine powder in the product. Therefore, it is required to obtain excellent water absorption characteristics while utilizing fine powder, and as the water absorption characteristics, for example, in consideration of the usage mode in which the water absorption resin particles are pressurized, excellent water absorption characteristics under pressure are obtained. Is required.
  • the present inventor focused on utilizing fine powder that passes through a sieve having a mesh size of 212 ⁇ m or less, and obtained water-absorbent resin particles having excellent water absorption characteristics under pressure by using such fine powder. I was inspired. On the other hand, the present inventor obtains one obtained by subjecting each of a plurality of polymer particle groups classified by a sieve having a mesh size of 212 ⁇ m or less to surface cross-linking and then subjecting fine powder to surface cross-linking. It has been found that by mixing the polymer particle group with another polymer particle group, it is possible to obtain water-absorbent resin particles having excellent water-absorbing properties under pressure while utilizing fine powder.
  • One aspect of the present invention is the polymer particle group A2 obtained by subjecting the polymer particle group A1 remaining on the sieve S1 to surface cross-linking when the polymer particle group is classified by the sieve S1 having a mesh size of 212 ⁇ m or less.
  • a method for producing a water-absorbent resin particle which comprises a step of obtaining the sex resin particle.
  • polymer particles having excellent water absorption characteristics under pressure can be obtained by subjecting fine powder passing through a sieve having a mesh size of 212 ⁇ m or less to surface cross-linking under specific conditions. It was.
  • Another aspect of the present invention is that when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less, the polymer particle group B1 that has passed through the sieve and the surface cross-linking agent are mixed at 0 to 20 ° C.
  • the present invention provides a method for producing polymer particles, which comprises a step of subjecting the polymer particle group B1 to surface crosslinks.
  • Another aspect of the present invention is the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less using a surface cross-linking agent solution containing alcohol and water.
  • a method for producing polymer particles which comprises a step of subjecting a surface crosslink and has a volume ratio of the alcohol to water of 0.25 to 2.00.
  • 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.
  • Room temperature means 25 ° C.
  • a particle group which is an aggregate of particles may be described as "particle”.
  • CRC is an abbreviation for Centrifuge Retention Capacity (centrifuge holding capacity).
  • the CRC 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).
  • the absorption ratio (AAP) under pressurization of 4.83 kPa (0.7 psi) can be measured by the method described in the column of [Example] described later.
  • the CRC and the absorption ratio under pressurization of 4.83 kPa the measured value at room temperature can be used.
  • the mass of the polymer particle group (for example, the expression such as "100 parts by mass of the polymer particle group" below) is the solid content of the polymer particle group. Means.
  • the method for producing the water-absorbent resin particles according to the present embodiment is when the polymer particle group is classified by a sieve S1 having a mesh size of 212 ⁇ m or less.
  • the polymer particle group A2 obtained by surface cross-linking the polymer particle group A1 remaining on the sieve S1 and the polymer particle group A2 having a mesh size of 212 ⁇ m or less were used to classify the polymer particle group, the polymer particle group passed through the sieve S2.
  • the present invention comprises a mixing step of obtaining water-absorbent resin particles (water-absorbent resin particle group) by mixing the polymer particle group B1 obtained by subjecting the polymer particle group B1 with a surface-crosslinked polymer particle group B2.
  • suitable surface cross-linking can be performed on each of the polymer particle group A1 and the polymer particle group B1.
  • suitable surface cross-linking By mixing the polymer particle group A2 and the polymer particle group B2 obtained by performing suitable surface cross-linking, for example, a uniform surface cross-linking state can be achieved in the entire water-absorbent resin particles.
  • the factors capable of obtaining excellent water absorption characteristics are not limited to the above-mentioned contents.
  • the suitable surface cross-linking conditions for the polymer particle group A1 and the polymer particle group B1 are the same, the same conditions may be used for the surface cross-linking after classification.
  • the mixing amount of the polymer particle group B2 is preferably less than 50 parts by mass, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, and 35 parts by mass or less from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is particularly preferable, 33 parts by mass or less is extremely preferable, 30 parts by mass or less is very preferable, 25 parts by mass or less is even more preferable, 20 parts by mass or less is further preferable, 15 parts by mass or less is particularly preferable, and 12 parts by mass or less. Is extremely preferable.
  • the mixing amount of the polymer particle group B2 is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, from the viewpoint of enhancing the utilization efficiency of the fine powder. 9 parts by mass or more is extremely preferable, 10 parts by mass or more is very preferable, and 11 parts by mass or more is even more preferable. From these viewpoints, the mixing amount of the polymer particle group B2 is preferably 1 part by mass or more and less than 50 parts by mass, more preferably 5 to 30 parts by mass, and further preferably 10 to 20 parts by mass.
  • the CRC of the polymer particle group A2 is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 27 g / g or more, particularly preferably 28 g / g or more, extremely preferably 29 g / g or more, and very preferably 30 g / g or more.
  • 31 g / g or more is even more preferable
  • 33 g / g or more is further preferable
  • 35 g / g or more is particularly preferable
  • 36 g / g or more is extremely preferable.
  • the CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, particularly preferably 45 g / g or less, extremely preferably 40 g / g or less, and very preferably 38 g / g or less. .. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 50 g / g, and even more preferably 25 to 40 g / g.
  • the absorption ratio (AAP) of the polymer particle group A2 under pressurization of 4.83 kPa is preferably 6.0 g / g or more, more preferably 6.5 g / g or more, further preferably 7.0 g / g or more, and 7. 5 g / g or more is particularly preferable, 8.0 g / g or more is extremely preferable, 8.5 g / g or more is very preferable, 9.0 g / g or more is further preferable, 10.0 g / g or more is further preferable, and 10.0 g / g or more is further preferable.
  • the upper limit of the absorption ratio (AAP) of the polymer particle group A2 under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less. Or, it may be 20.0 g / g or less.
  • the CRC of the polymer particle group B2 is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 31 g / g or more, extremely preferably 32 g / g or more, and very preferably 33 g / g or more. , 34 g / g or more is even more preferable.
  • the CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, particularly preferably 45 g / g or less, extremely preferably 40 g / g or less, and very preferably 35 g / g or less. .. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 50 g / g, and even more preferably 30 to 40 g / g.
  • the absorption ratio (AAP) of the polymer particle group B2 under pressure of 4.83 kPa is preferably 8.0 g / g or more, more preferably 9.0 g / g or more, further preferably 10.0 g / g or more, and 12. 0 g / g or more is particularly preferable, 15.0 g / g or more is extremely preferable, 18.0 g / g or more is very preferable, and 19.0 g / g or more is even more preferable.
  • the upper limit of the absorption ratio (AAP) of the polymer particle group B2 under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less. Or, it may be 20.0 g / g or less.
  • At least two or more polymer particle groups among the classified groups may be surface-crosslinked and mixed with each other. In this case, all of the classifieds may be mixed with each other, and some of the classified polymer particle groups may not be mixed.
  • the temperature at which the polymer particle group A2 and the polymer particle group B2 are mixed in the mixing step may be 5 ° C. or higher and lower than 100 ° C., 5 to 90 ° C., or 5 to 80 ° C.
  • the polymer particle group A2 is a polymer particle group obtained by subjecting the polymer particle group A1 remaining on the sieve S1 to surface cross-linking when the polymer particle group is classified by a sieve S1 having a mesh size of 212 ⁇ m or less. ..
  • the polymer particle group B2 is a polymer particle group obtained by subjecting the polymer particle group B1 that has passed through the sieve S2 to surface cross-linking when the polymer particle group is classified by a sieve S2 having a mesh size of 212 ⁇ m or less.
  • the polymer particle group to be classified using the sieve S1 or the sieve S2 is a polymer particle that has passed through the sieve when the polymer particle group is classified with a sieve having an opening of 850 ⁇ m or more from the viewpoint of removing coarse particles. It may be a group.
  • the polymer particle group to be classified using the sieve S1 or the sieve S2 has a weight remaining on the sieve when the polymer particle group is classified with a sieve having an opening of 45 ⁇ m or less from the viewpoint of removing extremely small fine powder. It may be a coalesced particle group.
  • the polymer particle group A1 and the polymer particle group B1 may be obtained by classifying the same polymer particle group from each other, or may be obtained by classifying different polymer particle groups from each other.
  • the sieve S1 and the sieve S2 are the same sieve (the same product).
  • the sieve S1 and the sieve S2 may be different sieves or the same sieves.
  • the polymer particle group C is classified by a sieve S1 (the sieve S1 and the sieve S2 are the same sieves) before the mixing step to classify the polymer.
  • the classification step I for obtaining the particle group A1 and the polymer particle group B1 may be provided.
  • the method for producing the water-absorbent resin particles according to the second embodiment includes a classification step IIa for obtaining the polymer particle group A1 by classifying the polymer particle group D1 with a sieve S1 before the mixing step, and a polymer particle group.
  • a classification step IIb for obtaining the polymer particle group B1 by classifying the polymer particle group D2 different from D1 with a sieve S2 may be provided.
  • the meshes of the sieve S1 and the sieve S2 may be the same or different from each other.
  • the sieves S1 and S2, which are different sieves from each other may be classified (the sieve S2 may be a sieve different from the sieve S1).
  • one of the classification step IIa and the classification step IIb was performed using the sieves S1 and S2 which are the same sieves (same thing) as each other.
  • the other of the classification step IIa and the classification step IIb may be performed later (that is, the classification may be repeated with the same sieve).
  • the polymer particle group D1 and the polymer particle group D2 in the method for producing water-absorbent resin particles according to the second embodiment are different polymer particle groups from each other.
  • the polymer particle group D1 and the polymer particle group D2 may be a polymer particle group produced under the same conditions.
  • the polymer particle group of one of the polymer particle group D1 and the polymer particle group D2 is a polymer particle group obtained by subjecting the other of the polymer particle group D1 and the polymer particle group D2 to various treatments. Good.
  • the polymer particle group of one of the polymer particle group D1 and the polymer particle group D2 is before or after various treatments of the other polymer particle group of the polymer particle group D1 and the polymer particle group D2. It may be a polymer particle group different from the later polymer particle group.
  • the polymer particle group to be classified can be classified into a plurality of polymer particle groups, and the sieve S1 or the sieve S2 may be used to classify the polymer particle group into two polymer particle groups. It may be classified into three or more polymer particle groups by a plurality of sieves containing.
  • the polymer particle group C may be classified into the polymer particle group A1 and the polymer particle group B1 by a sieve S1.
  • the polymer particle group D1 may be classified into two by a sieve S1, and the polymer particle group D1 may be classified into two by a plurality of sieves including the sieve S1. It may be classified into three or more.
  • the polymer particle group D2 may be classified into two by a sieve S2, and the polymer particle group D2 may be classified into two by a plurality of sieves including the sieve S2. It may be classified into three or more.
  • a sieve having a mesh size of 212 ⁇ m or less As the sieve having a mesh size of 212 ⁇ m or less (sieve S1 and sieve S2), a sieve having a mesh size of 212 ⁇ m or less specified in JIS Z8801-1 may be used.
  • the mesh size of the sieve may be 180 ⁇ m or less.
  • the mesh size of the sieve may be 45 ⁇ m or more, 75 ⁇ m or more, 90 ⁇ m or more, 106 ⁇ m or more, 125 ⁇ m or more, 150 ⁇ m or more, or 180 ⁇ m or more.
  • the CRC of the polymer particle group to be classified using the sieve S1 or the sieve S2 is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 35 g / g or more, from the viewpoint of easily increasing the absorption amount when used in an absorbent article. 39 g / g or more is extremely preferable.
  • the CRC is preferably 80 g / g or less, preferably 70 g / g or less, further preferably 60 g / g or less, particularly preferably 55 g / g or less, and particularly preferably 50 g / g or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is extremely preferable, 45 g / g or less is very preferable, and 40 g / g or less is even more preferable. From these viewpoints, the CRC is preferably 20 to 80 g / g, more preferably 25 to 60 g / g, and even more preferably 30 to 50 g / g.
  • the medium particle size of the polymer particle group to be classified using the sieve S1 or the sieve S2 is preferably in the following range.
  • the medium particle size is from the viewpoint that it is easy to obtain excellent water absorption characteristics under pressure in the water-absorbent resin particles, and from the viewpoint that it is easy to maintain good absorption performance when used in an absorbent article by avoiding gel blocking. , 200 ⁇ m or more is preferable, 230 ⁇ m or more is more preferable, and 250 ⁇ m or more is further preferable.
  • the medium particle size is preferably 600 ⁇ m or less, more preferably 550 ⁇ m or less, further preferably 500 ⁇ m or less, particularly preferably 450 ⁇ m or less, and extremely preferably 400 ⁇ m or less, from the viewpoint of easily keeping the tactile sensation soft when used in an absorbent article. .. From these viewpoints, the medium particle size is preferably 200 to 600 ⁇ m, more preferably 230 to 500 ⁇ m, and even more preferably 250 to 400 ⁇ m.
  • the medium particle size is preferably 260 ⁇ m or more, more preferably 280 ⁇ m or more, further preferably 300 ⁇ m or more, particularly preferably 330 ⁇ m or more, and particularly preferably 350 ⁇ m or more, from the viewpoint of easily obtaining more excellent water absorption characteristics under pressure in the water-absorbent resin particles. Is extremely preferable.
  • the medium particle size is preferably 350 ⁇ m or less, more preferably 320 ⁇ m or less, further preferably 300 ⁇ m or less, particularly preferably 280 ⁇ m or less, and extremely preferably 260 ⁇ m or less, from the viewpoint of easily obtaining a more excellent CRC in the water-absorbent resin particles.
  • the medium particle size can be measured by the method described in the [Example] column described later.
  • the medium particle size is a mass-based particle size, and a measured value at room temperature can be used.
  • the method for producing the water-absorbent resin particles according to the present embodiment includes a surface cross-linking step I in which the polymer particle group A1 is surface-crosslinked to obtain the polymer particle group A2 before the mixing step and after the classification step.
  • a surface cross-linking step II in which the polymer particle group B1 is surface-crosslinked to obtain the polymer particle group B2 may be provided.
  • the conditions for surface cross-linking in the surface cross-linking step I and the surface cross-linking step II may be the same as each other or may be different from each other.
  • the amount of the surface cross-linking agent used in the surface cross-linking step II is the surface in the surface cross-linking step I from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. It may be larger than the amount of the cross-linking agent used.
  • the surface cross-linking conditions in the surface cross-linking step II are compared with the surface cross-linking conditions in the surface cross-linking step I from the viewpoint of easily obtaining excellent water absorption characteristics under pressure, and the surface of the particles in the polymer particle group with respect to the inside It is preferable that the absorption rate of the cross-linking agent is slow.
  • the polymer particle group B1 which is a fine powder tends to have a higher absorption rate of the surface cross-linking agent than the polymer particle group A1, but in the polymer particle group B1, the absorption rate of the surface cross-linking agent to the inside of the particles is lowered.
  • the mixing temperature of the surface cross-linking agent in the surface cross-linking step II may be lower than the mixing temperature of the surface cross-linking agent in the surface cross-linking step I from the viewpoint of easily reducing the absorption rate of the surface cross-linking agent into the inside of the particles (mixing). Details of the temperature will be described later).
  • the amount of alcohol used in the surface cross-linking step II is such that the amount of alcohol that is difficult to be absorbed inside the particles increases, so that the absorption rate of the surface cross-linking agent into the inside of the particles tends to decrease. (As the amount used, for example, "volume ratio of alcohol to water" or "amount of alcohol used in the surface cross-linking agent solution” described later can be used).
  • the polymer particle group can be surface-crosslinked using a surface cross-linking agent for performing surface cross-linking.
  • a surface cross-linking agent for example, a compound containing two or more functional groups (reactive functional groups, for example, hydroxyl groups) having reactivity with a functional group derived from an ethylenically unsaturated monomer can be used.
  • the surface cross-linking agent include polyols such as 1,4-butanediol, diethylene glycol, triethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene glycol diglycidyl ether.
  • Haloepoxy compounds such as; compounds having two or more reactive functional groups such as isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol , 3-butyl-3-oxetanemethanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, 3-butyl-3-oxetaneethanol and other oxetane compounds; Oxazoline compounds; ethylene carbonate, propylene carbonate, 4,5-dimethyl-1,3-diox
  • the surface cross-linking agent may be used alone or in combination of two or more.
  • the surface cross-linking agent preferably contains a carbonate compound, more preferably contains an alkylene carbonate, and further preferably contains an ethylene carbonate, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • the polymer particle group can be surface-crosslinked using the following amount of the surface cross-linking agent for 100 parts by mass of the polymer particle group.
  • the amount of the surface cross-linking agent used is preferably in the following range with respect to 100 parts by mass of the polymer particle group.
  • the amount of the surface cross-linking agent used is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, still more preferably 0.05 parts by mass or more, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • 0.1 parts by mass or more is particularly preferable, 0.3 parts by mass or more is extremely preferable, 0.5 parts by mass or more is very preferable, 0.8 parts by mass or more is even more preferable, and 1.0 parts by mass or more is further preferable.
  • 1.2 parts by mass or more is particularly preferable, and 1.4 parts by mass or more is extremely preferable.
  • the amount of the surface cross-linking agent used is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, and particularly preferably 4 parts by mass or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • the amount of the surface cross-linking agent used is preferably 0.005 to 10 parts by mass, more preferably 0.01 to 10 parts by mass, further preferably 0.01 to 5 parts by mass, and 0.01 to 3 parts. Parts by mass are particularly preferable, parts by mass of 0.1 to 3 are extremely preferable, and parts by mass of 0.5 to 3 are very preferable.
  • the amount of the surface cross-linking agent used is preferably 1 to 10 parts by mass.
  • the amount of the surface cross-linking agent used may be 1.4 parts by mass or less, 1.2 parts by mass or less, 1 part by mass or less, or 0.9 parts by mass or less.
  • the surface cross-linking step it is possible to carry out surface cross-linking on 100 parts by mass of the polymer particle group B1 using the surface cross-linking agent solution (liquid containing the surface cross-linking agent) containing each of the above-mentioned amounts of the surface cross-linking agent.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing 1 part by mass or more (for example, 1 to 10 parts by mass) of the surface cross-linking agent.
  • the polymer particle group can be surface-crosslinked by using the following amount of a carbonate compound (for example, alkylene carbonate) with respect to 100 parts by mass of the polymer particle group.
  • a carbonate compound for example, alkylene carbonate
  • the amount of the carbonate compound used is preferably in the following range with respect to 100 parts by mass of the polymer particle group.
  • the amount of the carbonate compound used is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, further preferably 0.1 part by mass or more, and 0, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • .3 parts by mass or more is particularly preferable, 0.5 parts by mass or more is extremely preferable, 0.6 parts by mass or more is very preferable, 0.7 parts by mass or more is further preferable, and 0.8 parts by mass or more is further preferable. , 0.9 parts by mass or more is particularly preferable.
  • the amount of the carbonate compound used is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, particularly preferably 4 parts by mass or less, and 3 parts by mass from the viewpoint of easily obtaining an appropriate CRC.
  • the following is extremely preferable, 2 parts by mass or less is very preferable, and 1 part by mass or less is even more preferable.
  • the amount of the carbonate compound used is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, further preferably 0.01 to 3 parts by mass, and 0.1 to 3 parts by mass. Parts are particularly preferable, and 0.5 to 3 parts by mass are extremely preferable.
  • the amount of the carbonate compound used is preferably 0.5 to 10 parts by mass.
  • the amount of the carbonate compound used may be 0.9 parts by mass or less, 0.7 parts by mass or less, or 0.5 parts by mass or less.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound, for example, 0.5 parts by mass.
  • a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound for example, 0.5 parts by mass.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked.
  • the polymer particle group and the surface cross-linking agent may be mixed at the following mixing temperature to perform surface cross-linking on the polymer particle group.
  • the mixing temperature of the polymer particle group and the surface cross-linking agent in the surface cross-linking step is preferably in the following range.
  • the mixing temperature is preferably 0 ° C. or higher, more preferably 1 ° C. or higher, further preferably 3 ° C. or higher, particularly preferably 5 ° C. or higher, and exceeding 5 ° C. or higher from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is extremely preferable, 10 ° C.
  • the mixing temperature is preferably 50 ° C. or lower, more preferably 45 ° C. or lower, further preferably 40 ° C. or lower, particularly preferably 35 ° C. or lower, and extremely preferably 30 ° C. or lower, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. , Less than 30 ° C. is very preferable, 25 ° C. or lower is even more preferable, less than 25 ° C. is further preferable, 20 ° C. or lower is particularly preferable, less than 20 ° C. is extremely preferable, 18 ° C. or lower is very preferable, and 15 ° C.
  • the mixing temperature is preferably 0 to 50 ° C., more preferably 5 to 30 ° C., and even more preferably 10 to 25 ° C.
  • the mixing temperature is also preferably 0 to 20 ° C.
  • the mixing temperature may exceed 15 ° C. or higher, may be 20 ° C. or higher, may exceed 20 ° C. or higher, and may be 22 ° C. or higher.
  • the polymer particle group B1 and the surface cross-linking agent can be mixed at the above-mentioned mixing temperatures to perform surface cross-linking on the polymer particle group B1.
  • the polymer particle group B1 and the surface can be cross-linked.
  • the cross-linking agent can be mixed at 20 ° C. or lower (for example, 0 to 20 ° C.) to perform surface cross-linking on the polymer particle group B1.
  • the surface cross-linking step may be carried out in the presence of water, and the presence of water in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the monomer (for example, ethylenically unsaturated monomer) in the polymer particle group. You may go below. By adjusting the amount of water in the surface cross-linking step, the cross-linking in the vicinity of the particle surface can be adjusted.
  • the polymer particle group can be surface-crosslinked using a surface cross-linking agent solution containing at least one selected from the group consisting of a water-soluble organic solvent and water.
  • a water-soluble organic solvent include alcohol and the like.
  • alcohols lower alcohols such as methanol, ethanol, propanol and isopropanol; ketones such as acetone; ethers such as dioxane; amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; ethylene glycol, Examples thereof include polyhydric alcohols such as propylene glycol.
  • the alcohol at least one selected from the group consisting of a compound having two or more (for example, two) hydroxyl groups and a compound having one hydroxyl group may be used.
  • the alcohol preferably contains at least one selected from the group consisting of propylene glycol and isopropanol, and more preferably isopropanol, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • the water-soluble organic solvent may be a compound corresponding to the above-mentioned surface cross-linking agent.
  • the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing isopropanol.
  • the surface cross-linking step it is possible to carry out surface cross-linking on the polymer particle group using a surface cross-linking agent solution containing alcohol, and the polymer particle group using the surface cross-linking agent solution containing the following amount of alcohol.
  • a surface cross-linking agent solution containing alcohol can contain at least one selected from the group consisting of alcohols that are surface cross-linking agents and alcohols that are not surface cross-linking agents.
  • the amount of alcohol used in the surface cross-linking agent solution is preferably in the following range based on the total mass of the surface cross-linking agent solution or the total amount of the surface cross-linking agent, alcohol and water that do not correspond to alcohol.
  • the amount of alcohol used is preferably 10% by mass or more, more preferably 12% by mass or more, further preferably 15% by mass or more, and particularly preferably 17% by mass or more, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 18% by mass or more is extremely preferable, 20% by mass or more is very preferable, 22.5% by mass or more is further preferable, 25% by mass or more is further preferable, 27.5% by mass or more is particularly preferable, and 30% by mass or more. Is extremely preferable.
  • the amount of alcohol used is preferably 80% by mass or less, more preferably 75% by mass or less, further preferably 70% by mass or less, and particularly preferably 65% by mass or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 60% by mass or less is extremely preferable, 55% by mass or less is very preferable, and 52% by mass or less is even more preferable. From these viewpoints, the amount of alcohol used is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, further preferably 20 to 60% by mass, and particularly preferably 30 to 55% by mass. The amount of alcohol used is also preferably 20 to 80% by mass.
  • the amount of alcohol used may be 31% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, or 51% by mass or more.
  • the amount of alcohol used may be 51% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 31% by mass or less.
  • the surface cross-linking step it is possible to carry out surface cross-linking on the polymer particle group B1 by using the above-mentioned surface cross-linking agent solution containing each amount of alcohol used, for example, 20% by mass or more of alcohol (for example, 20 to 20 to 20).
  • the polymer particle group B1 can be surface-crosslinked using a surface-crosslinking agent solution containing 80% by mass).
  • the volume ratio of alcohol to water is preferably in the following range.
  • the volume ratio is preferably 0.10 or more, more preferably 0.20 or more, further preferably 0.25 or more, particularly preferably 0.30 or more, and 0. 35 or more is extremely preferable, 0.40 or more is very preferable, and 0.45 or more is even more preferable.
  • the volume ratio is preferably 2.00 or less, more preferably 1.80 or less, further preferably 1.50 or less, particularly preferably 1.40 or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 30 or less is extremely preferable, and 1.20 or less is very preferable.
  • the volume ratio is preferably 0.10 to 2.00, more preferably 0.25 to 1.50, and even more preferably 0.45 to 1.20.
  • the volume ratio is also preferably 0.25 to 2.00.
  • the volume ratio may be 0.50 or more, 0.70 or more, 0.90 or more, 1.00 or more, 1.10 or more, or 1.20 or more.
  • the volume ratio may be less than 1.20, 1.10 or less, 1.00 or less, 0.90 or less, 0.70 or less, 0.50 or less, or 0.30 or less.
  • the amount of alcohol used includes the amount of surface cross-linking agent used.
  • the volume ratio may be a volume ratio at 20 ° C. and can be calculated based on the density of alcohol and water at 20 ° C.
  • the density of propylene glycol is 1.04 g / cm 3
  • the density of isopropanol is 0.79 g / cm 3
  • the surface cross-linking step may be an embodiment in which the polymer particle group B1 is subjected to surface cross-linking using a surface cross-linking agent solution containing alcohol and water, and the volume ratio of alcohol to water is each of the above-mentioned volume ratios, for example.
  • the volume ratio of alcohol to water may be 0.25 or more (for example, 0.25 to 2.00).
  • the amount of alcohol used is preferably in the following range with respect to 100 parts by mass of the polymer particle group.
  • the amount of alcohol used is preferably 0.1 part by mass or more, more preferably 0.15 part by mass or more, further preferably 0.25 part by mass or more, and 0. 5 parts by mass or more is particularly preferable, 0.6 parts by mass or more is extremely preferable, 0.75 parts by mass or more is very preferable, 1 part by mass or more is further preferable, and 1.25 parts by mass or more is further preferable. 5 parts by mass or more is particularly preferable, 1.75 parts by mass or more is extremely preferable, 2 parts by mass or more is very preferable, 2.25 parts by mass or more is further preferable, and 2.5 parts by mass or more is further preferable.
  • the amount of alcohol used is preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, further preferably 4 parts by mass or less, and 3.5 parts by mass or less from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is particularly preferable, 3 parts by mass or less is extremely preferable, and 2.6 parts by mass or less is very preferable. From these viewpoints, the amount of alcohol used is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass, and even more preferably 1 to 3 parts by mass. The amount of alcohol used is 2.5 parts by mass or less, 2 parts by mass or less, 1.5 parts by mass or less, 1.1 parts by mass or less, 0.8 parts by mass or less, or 0.6 parts by mass or less. May be good.
  • the amount of alcohol used includes the amount of surface cross-linking agent used.
  • the surface cross-linking step it is possible to carry out surface cross-linking on 100 parts by mass of the polymer particle group B1 using the above-mentioned surface cross-linking agent solution containing each amount of alcohol, for example, 0.6 parts by mass or more.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing (for example, 0.6 to 5 parts by mass) alcohol.
  • the treatment temperature in the surface cross-linking step is appropriately set according to the surface cross-linking agent used, and may be 20 to 250 ° C.
  • the treatment temperature in the surface cross-linking step is preferably a temperature lower than the boiling point or decomposition temperature of the surface cross-linking agent.
  • the treatment time is preferably 1 to 200 minutes, more preferably 5 to 100 minutes, further preferably 5 to 60 minutes, and particularly preferably 5 to 45 minutes.
  • the surface-crosslinked polymer particle group may be classified by a sieve having an opening of 850 ⁇ m from the viewpoint of removing coarse particles.
  • the surface-crosslinked polymer particle group may be classified by a sieve having a mesh size of 45 ⁇ m from the viewpoint of removing extremely small fine powder.
  • the polymer particles (polymer) comprising a surface cross-linking step of subjecting the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less.
  • a method for producing the particle group B2) can be provided. It can be said that the method for producing the polymer particles is a method for producing fine powder or a method for cross-linking fine powder.
  • the method for producing polymer particles according to the present embodiment it is possible to obtain polymer particles having excellent water absorption characteristics under pressure as fine powders having excellent water absorption characteristics, and the fine powders can be effectively utilized. Can be done.
  • polymer particles having excellent CRC in addition to excellent water absorption characteristics under pressure can be obtained as fine powder having excellent water absorption characteristics.
  • the same conditions as the above-mentioned conditions for the surface cross-linking step of the water-absorbent resin particle manufacturing method according to the present embodiment can be arbitrarily set. Can be used.
  • a surface cross-linking agent solution containing each of the above-mentioned amounts of the surface cross-linking agent used for the surface cross-linking agent in the method for producing water-absorbent resin particles is used, and the opening is 212 ⁇ m.
  • the embodiment may include a step of subjecting 100 parts by mass of the polymer particle group B1 that has passed through the sieve to surface crosslink when the polymer particle group is classified by the following sieve, for example, 1 part by mass or more (for example, 1). It may be an embodiment including a step of subjecting 100 parts by mass of the polymer particle group B1 to surface cross-linking using a surface cross-linking agent solution containing ( ⁇ 10 parts by mass) of the surface cross-linking agent.
  • a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound (for example, alkylene carbonate) used for the carbonate compound in the method for producing water-absorbent resin particles is used to open the openings.
  • the embodiment may include a step of surface cross-linking 100 parts by mass of the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified with a sieve of 212 ⁇ m or less, for example, 0.5 parts by mass or more.
  • An embodiment may include a step of surface cross-linking 100 parts by mass of the polymer particle group B1 with a surface cross-linking agent solution containing a carbonate compound (for example, alkylene carbonate) of (for example, 0.5 to 10 parts by mass). ..
  • a carbonate compound for example, alkylene carbonate
  • the polymer particle group B1 that has passed through the sieve and the surface cross-linking agent are combined with a water-absorbent resin.
  • the embodiment may include a step of subjecting the polymer particle group B1 to surface cross-linking by mixing at each of the above-mentioned mixing temperatures in the method for producing particles.
  • the polymer particle group B1 and the surface cross-linking agent are heated to 20 ° C. or lower (
  • it may be an embodiment including a step of subjecting the polymer particle group B1 to surface cross-linking by mixing at 0 to 20 ° C.).
  • a polymer particle group that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less using a surface cross-linking agent solution containing isopropanol It may be an embodiment including a step of subjecting B1 to surface cross-linking.
  • the above-mentioned amounts of alcohol used in the method for producing the water-absorbent resin particles (the total mass of the surface cross-linking agent solution, or the surface cross-linking agent, alcohol and water which do not correspond to alcohol).
  • the polymer particle group is classified with a sieve having a mesh size of 212 ⁇ m or less by using a surface cross-linking agent solution containing alcohol (the amount used based on the total amount of the above and the amount used with respect to 100 parts by mass of the polymer particle group).
  • the embodiment may include a step of subjecting the polymer particle group B1 that has passed through the sieve to crosslink the surface.
  • a surface crosslinking agent solution containing 20% by mass or more (for example, 20 to 80% by mass) of alcohol may be provided, which may include a step of subjecting 100 parts by mass of the polymer particle group B1 to surface cross-linking. It may be an embodiment including a step of subjecting 100 parts by mass of the polymer particle group B1 to surface crosslinks using the above.
  • the polymer passed through the sieve.
  • the embodiment may include a step of subjecting the particle group B1 to surface crosslink, and the volume ratio of the alcohol to water may be each of the above-mentioned volume ratios in the method for producing the water-absorbent resin particles, for example, 0.25 or more ( For example, it may be 0.25 to 2.00).
  • the method for producing water-absorbent resin particles according to the present embodiment is a cross-linking weight for obtaining a polymer particle group to be classified using a sieve S1 or a sieve S2 before a classification step, a surface cross-linking step and a mixing step. It may be provided with a polymerization step to obtain a coalesced gel. In the polymerization step, for example, a monomer composition containing an ethylenically unsaturated monomer can be polymerized.
  • the monomer composition may contain water, an organic solvent, and the like.
  • the monomer composition may be a monomer aqueous solution.
  • Examples of the polymerization method of the monomer composition include an aqueous solution polymerization method and a bulk polymerization method. Among these, the aqueous solution polymerization method is preferable from the viewpoint that good water absorption characteristics (excellent water absorption characteristics under pressure, etc.) can be easily obtained and the polymerization reaction can be easily controlled. In the following, a case where the aqueous solution polymerization method is used as an example of the polymerization method will be described.
  • ethylenically unsaturated monomer a water-soluble ethylenically unsaturated monomer can be used.
  • the ethylenically unsaturated monomer include ⁇ , ⁇ -unsaturated carboxylic acids such as (meth) acrylate, 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
  • the ethylenically unsaturated monomer preferably contains at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof from the viewpoint of industrial availability.
  • 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 the 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 neutralizer is from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained by increasing the osmotic pressure, and the excess alkaline neutralizer. From the viewpoint of suppressing defects caused by the presence of, 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 from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. , 35% by mass or more 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 from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. It is preferably 45% by mass or less, or 40% by mass or less. 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 content of the structural unit derived from the (meth) acrylic acid compound is the above-mentioned (meth) acrylic acid based on the total mass of the structural units constituting the water-absorbent resin particles.
  • the content of the compound (the total amount of monomers contained in the monomer composition and / or the total amount of ethylenically unsaturated monomers contained in the monomer composition was used as a reference (meth). ) Content of acrylic acid compound) is preferably in each of the above ranges.
  • 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 obtaining good water absorption characteristics (water absorption characteristics under pressure, etc.), and contains peroxides. Is more preferable.
  • 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 characteristics (water absorption characteristics under pressure, 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 that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained.
  • the content of the polymerization initiator is preferably in the following range with respect to 1 mol of the (meth) acrylic acid compound.
  • the content of the polymerization initiator is 0.001 mmol or more, 0.003 mmol or more, 0 from the viewpoint of easily obtaining good water absorption characteristics (water absorption characteristics under pressure, etc.) and shortening the polymerization reaction time. .015 mmol or more, 0.03 mmol or more, 0.06 mmol or more, 0.08 mmol or more, 0.1 mmol or more, 0.15 mmol or more, 0.2 mmol or more, or 0.25 mmol or more is preferable. ..
  • the content of the polymerization initiator is 5 mmol or less, 4 mmol or less, 2 mmol or less from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained and a rapid polymerization reaction can be easily avoided. It is preferably 1 mmol or less, or 0.8 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-linking polymer can have a cross-linking structure by the internal cross-linking agent in addition to the self-cross-linking structure by the polymerization reaction as the internal cross-linking structure.
  • Examples of the internal cross-linking agent include compounds having two or more reactive functional groups (for example, polymerizable unsaturated groups).
  • Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as (poly) ethylene glycol, (poly) propylene glycol, trimethylolpropane, glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin.
  • unsaturated polyesters obtained by reacting the above polyol with 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.
  • the internal cross-linking agent has good water absorption characteristics (water absorption characteristics under pressure, etc.).
  • polyethylene glycol di (meth) acrylate trimethylolpropantri (meth) acrylate
  • polyethylene glycol diglycidyl ether trimethylolpropantri (meth) acrylate
  • polyethylene glycol diglycidyl ether ethylene glycol diglycidyl ether
  • polypropylene glycol diglycidyl ether ethylene glycol diglycidyl ether
  • poly glycerinji preferably contains at least one selected from the group consisting of glycidyl ethers.
  • the content of the internal cross-linking agent is preferably in the following range with respect to 1 mol of the (meth) acrylic acid compound.
  • the content of the internal cross-linking agent is 0.01 mmol or more, 0.05 mmol or more, 0.08 mmol or more, 0.1 mmol or more from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. , 0.15 mmol or more, or 0.2 mmol or more is preferable.
  • the content of the internal cross-linking agent is preferably 10 mmol or less, 8 mmol or less, 5 mmol or less, 3 mmol or less, or 2 mmol or less from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. .. From these viewpoints, the content of the internal cross-linking agent is preferably 0.01 to 10 mmol.
  • 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 maximum value of the polymerization temperature may be 25 ° C. or higher, 30 ° C. or higher, 40 ° C. or higher, 50 ° C. or higher, or 60 ° C. or higher.
  • the maximum value of the polymerization temperature may be 110 ° C. or lower, 105 ° C. or lower, 100 ° C. or lower, or 95 ° C. or lower.
  • the maximum value of the polymerization temperature may be 25 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 water-absorbent resin particles according to the present embodiment includes a rough crushing step of coarsely crushing the crosslinked polymer gel obtained in the polymerization step to obtain a coarse crushed product (for example, a gel coarse crushed product), and a drying of the coarse crushed product.
  • a drying step of obtaining a dried product and a crushing step of crushing the dried product to obtain a crushed product may be provided.
  • These dried products or pulverized products can be used as a polymer particle group to be classified using a sieve S1 or a sieve S2.
  • a kneader pressurized kneader, double-armed kneader, etc.
  • a meat chopper a cutter mill, a pharma mill, or the like
  • a pharma mill a pharma mill, or the like
  • a dried product for example, gel dried product
  • a dried product can be obtained by removing liquid components (water, etc.) in the pyroclastic material by heating and / or blowing air.
  • the drying method may be natural drying, heat drying, blast drying, vacuum drying or the like.
  • the drying temperature is, for example, 70 to 250 ° C.
  • Crushers in the crushing process include roller mills (roll mills), stamp mills, jet mills, high-speed rotary crushers (hammer mills, pin mills, rotor beater mills, etc.), container-driven mills (rotary mills, vibration mills, planetary mills, etc.). ) And so on.
  • the water-absorbent resin particles according to the present embodiment can be obtained by the method for producing the water-absorbent resin particles according to the present embodiment.
  • the water-absorbent resin particles according to the present embodiment preferably have a structural unit derived from an ethylenically unsaturated monomer from the viewpoint of easily obtaining excellent water-absorbing properties under pressure.
  • the water-absorbent resin particles according to the present embodiment are crosslinked polymers (crosslinked weights having structural units derived from ethylenically unsaturated monomers) obtained by polymerizing a monomer containing an ethylenically unsaturated monomer. It is preferable to include coalescence).
  • the above-mentioned ethylenically unsaturated monomer related to the monomer composition in the polymerization step can be used.
  • the ethylenically unsaturated monomer preferably contains at least one compound selected from the group consisting of (meth) acrylic acid and a salt thereof from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • Examples of the shape of the water-absorbent resin particles according to the present embodiment include substantially spherical, crushed, and granular shapes.
  • the water-absorbent resin particles according to the present embodiment may be any water-absorbent resin particles as long as they can retain water, and the liquid to be absorbed may contain water.
  • the water-absorbent resin particles according to the present embodiment 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 water-absorbent resin particles according to the present embodiment are gel stabilizers; metal chelating agents (ethylenediaminetetraacetic acid and salts thereof, diethylenetriamine-5 acetic acid and salts thereof (for example, diethylenetriamine-5sodium acetate), etc.); fluidity improvers (lubricant).
  • metal chelating agents ethylenediaminetetraacetic acid and salts thereof, diethylenetriamine-5 acetic acid and salts thereof (for example, diethylenetriamine-5sodium acetate), etc.
  • fluidity improvers lubricant
  • Other components such as may be further contained.
  • Other components may be located inside, on the surface, or both of crosslinked polymers having structural units derived from ethylenically unsaturated monomers.
  • the water-absorbent resin particles according to the present embodiment may contain inorganic particles arranged on the surface of a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer.
  • the inorganic particles can be arranged on the surface of the crosslinked polymer.
  • the inorganic particles include silica particles such as amorphous silica.
  • the CRC of the water-absorbent resin particles according to this embodiment is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 31 g / g or more, extremely preferably 32 g / g or more, and very preferably 33 g / g or more.
  • 35 g / g or more is even more preferable
  • 38 g / g or more is further preferable
  • 40 g / g or more is particularly preferable
  • 45 g / g or more is extremely preferable.
  • the CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, and particularly preferably 46 g / g or less. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 55 g / g, and even more preferably 30 to 50 g / g.
  • the absorption ratio (AAP) of the water-absorbent resin particles according to the present embodiment under pressurization of 4.83 kPa is preferably 8.3 g / g or more, more preferably 8.5 g / g or more, and further preferably 9.0 g / g or more.
  • 10.0 g / g or more is particularly preferable, 15.0 g / g or more is extremely preferable, 16.0 g / g or more is very preferable, 17.0 g / g or more is even more preferable, and 18.0 g / g or more is preferable. Is more preferable.
  • the upper limit of the absorption ratio (AAP) of the water-absorbent resin particles under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less, Alternatively, it may be 20.0 g / g or less.
  • 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.
  • the fibrous material may be used alone or in combination of two or more.
  • hydrophilic fibers can be used as the fibrous material.
  • the mass ratio of the water-absorbent resin particles in the absorber may be 2 to 100% by mass, 10 to 80% by mass, or 20 to 60% by mass with respect to the total of the water-absorbent resin particles and the fibrous material.
  • the content of the water-absorbent resin particles in the absorber is preferably 100 to 1000 g, more preferably 150 to 800 g, and even more preferably 200 to 700 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient water absorption characteristics.
  • the content of the fibrous substance in the absorber is preferably 50 to 800 g, more preferably 100 to 600 g, and even more preferably 150 to 500 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient water absorption characteristics.
  • 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 adhesive binder may be used alone or in combination of two or more.
  • 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 adhesives 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 an inorganic powder (for example, amorphous silica), a deodorant, an antibacterial agent, a fragrance, and the like.
  • an inorganic powder for example, amorphous silica
  • the absorber may contain inorganic powder in addition to the inorganic particles in the water-absorbent resin particles.
  • the shape of the absorber according to the present embodiment may be, for example, a sheet shape.
  • the thickness of the absorber (for example, the thickness of the sheet-shaped absorber) may be, for example, 0.1 to 20 mm and 0.3 to 15 mm.
  • the absorbent article according to the present embodiment includes an absorber according to the present embodiment.
  • the absorbent article according to the present embodiment is a core wrap that retains the shape of the absorber; a liquid permeable sheet that is arranged on the outermost side of the side where the liquid to be absorbed enters; Examples thereof include a liquid permeable sheet arranged on the outermost side on the opposite side.
  • absorbent articles include diapers (for example, paper diapers), toilet training pants, incontinence pads, sanitary materials (sanitary napkins, tampons, etc.), sweat pads, pet sheets, simple toilet materials, 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 absorber 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 according to the present embodiment 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 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 present embodiment it is possible to provide a liquid absorbing method using the water-absorbent resin particles, the absorbent body 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 invention is not limited to the following experimental examples. If the temperature at the time of the experimental operation is not described below, the experimental operation can be performed at room temperature.
  • the obtained hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and subdivided.
  • the diameter of the hole in the plate located at the tip of the meat chopper was 6.4 mm.
  • This subdivided particulate hydrogel was spread and placed on a wire mesh having an opening of 0.8 cm ⁇ 0.8 cm, and then dried with hot air at 160 ° C. for 60 minutes to obtain a dried product.
  • the dried product was crushed using a centrifugal crusher (Resch, ZM200, screen diameter 1 mm, 6000 rpm), and the amorphous crushed polymer particles ( ⁇ ) (dry weight loss) were passed through a sieve having an opening of 850 ⁇ m. 1.8% by mass) was obtained.
  • the CRC of the polymer particles ( ⁇ ) was 39 g / g
  • the medium particle size was 352 ⁇ m
  • the proportion of polymer particles as a fraction) was 30% by mass.
  • the obtained hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and subdivided.
  • the diameter of the hole in the plate located at the tip of the meat chopper was 6.4 mm.
  • This subdivided particulate hydrogel was spread and placed on a wire mesh having an opening of 0.8 cm ⁇ 0.8 cm, and then dried with hot air at 160 ° C. for 60 minutes to obtain a dried product.
  • the dried product was crushed using a centrifugal crusher (Resch, ZM200, screen diameter 1 mm, 12000 rpm), and the amorphous crushed polymer particles ( ⁇ ) (dry weight loss) were passed through a sieve having an opening of 850 ⁇ m. : 1.2% by mass) was obtained.
  • the CRC of the polymer particles ( ⁇ ) was 51 g / g
  • the medium particle size was 254 ⁇ m
  • the mass ratio in the particle size range of “more than 0 ⁇ m and less than 180 ⁇ m” passeded through a sieve having an opening of 180 ⁇ m).
  • the proportion of polymer particles as a fraction) was 35% by mass.
  • the mass ratio of the polymer particles ( ⁇ ) and the polymer particles ( ⁇ ) in the particle size range of “more than 0 ⁇ m and less than 180 ⁇ m” was calculated by the following procedure. Using a continuous fully automatic sonic vibration type sieving measuring instrument (Robot Shifter RPS-205, manufactured by Seishin Enterprise Co., Ltd.), JIS standard meshes of 850 ⁇ m, 500 ⁇ m, 425 ⁇ m, 300 ⁇ m, 250 ⁇ m, 180 ⁇ m and 106 ⁇ m, and a saucer. The particle size distribution of 10 g of the polymer particles was measured in.
  • the mass of the particles remaining on each sieve was calculated as a mass percentage with respect to the total amount, and the particle size distribution was obtained.
  • the mass ratio in the particle size range of "more than 0 ⁇ m and less than 180 ⁇ m" was calculated based on the total amount of particles remaining on the sieve and the saucer having a mesh size of 180 ⁇ m.
  • the medium particle diameters of the polymer particles ( ⁇ ) and the polymer particles ( ⁇ ) were calculated by the following procedure. With respect to the above particle size distribution, by integrating the masses of the particles remaining on the sieve in order from the one with the largest particle diameter, the relationship between the mesh size of the sieve and the integrated value of the mass percentage of the particles remaining on the sieve is logarithmic. Plotted on probability paper. By connecting the plots on the probability paper with a straight line, the particle size corresponding to the cumulative mass percentage of 50% by mass was obtained as the medium particle size.
  • Example 2 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1b) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 3 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1c) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 4 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1d) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 5 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1e) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 6 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1f) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 7 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1g) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 8 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1h) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 9 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1i) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 10 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-2a) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 11 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-2b) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 12 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-1e) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 13 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-1f) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 15 90 parts by mass of polymer particles (X12) and 10 parts by mass of polymer particles (X13) are put into a 100 mL mayonnaise bottle, and then uniformly mixed by shaking with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. Water-absorbent resin particles were obtained.
  • Example 17 90 parts by mass of polymer particles (X22) and 10 parts by mass of polymer particles (X23) are put into a 100 mL mayonnaise bottle, and then uniformly mixed by shaking with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. Water-absorbent resin particles were obtained.
  • the CRC was measured by the following procedure with reference to the EDANA method (NWSP 241.0.R2 (15), page.769-778).
  • the CRC of the above-mentioned water-absorbent resin particles ( ⁇ ) and water-absorbent resin particles ( ⁇ ) was also measured in the same manner. The measurement was carried out in an environment where the temperature was 25 ° C. ⁇ 2 ° C. and the humidity was 50% ⁇ 10%.
  • 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 particles to be measured were precisely weighed and contained inside 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, the mass Ma of the non-woven fabric bag containing the mass of the gel was weighed. The non-woven fabric bag was subjected to the same operation as described above without accommodating the particles to be measured, and the mass Mb of the non-woven fabric bag was measured.
  • AAP absorption magnification
  • the weight 112 includes a disc portion 112a, a rod-shaped portion 112b extending from the center of the disc portion 112a in a direction perpendicular to the disc portion 112a, and a cylindrical portion 112c having a through hole inserted into the rod-shaped portion 112b in the center. have.
  • the disk portion 112a of the weight 112 has a diameter substantially equal to the inner diameter of the cylinder 114 so that it can be moved in the longitudinal direction of the cylinder 114 inside the cylinder 114.
  • the diameter of the cylindrical portion 112c is smaller than the diameter of the disc portion 112a.
  • the cylinder 114 Although one end of the cylinder 114 is open, it is shielded by a wire mesh 116, and the other end of the cylinder 114 is open so that the weight 112 can be inserted. Inside the cylinder 114, 0.90 g of particles 120 to be measured were uniformly sprayed on the wire mesh 116. Then, after the weight 112 is inserted into the cylinder 114 and the weight 112 is placed on the measurement target particle 120, the total mass of the measurement device 110 (the total mass of the measurement device 110 and the measurement target particle 120 before liquid absorption). Wa [g] was measured.
  • the above-mentioned measuring device 110 was placed on the filter paper 150 to absorb the liquid under a load. After 1 hour, the measuring device 110 was lifted, and the total mass of the measuring device 110 (total mass of the measuring device 110 and the measurement target particle 120 after absorbing the liquid) Wb [g] was measured.
  • each of the plurality of polymer particle groups obtained by classification was surface-crosslinked and then mixed.
  • a plurality of polymer particle groups obtained by classifying after the surface cross-linking without classifying before the surface cross-linking were mixed. It can be seen that excellent water absorption characteristics under pressure can be obtained.
  • the mixing temperature of the surface cross-linking agent and the amount of alcohol used in the surface cross-linking applied to the polymer particle group remaining on the sieve having a mesh size of 212 ⁇ m or less are under pressure. It can be seen that it does not significantly affect the water absorption characteristics of.
  • surface cross-linking applied to the polymer particle group passing through a sieve having a mesh size of 212 ⁇ m or less surface cross-linking applied to the polymer particle group passing through a sieve having a mesh size of 212 ⁇ m or less. It can be seen that the mixing temperature of the surface cross-linking agent and the amount of alcohol used in the above contribute greatly to the water absorption characteristics under pressure.
  • the amount of the surface cross-linking agent used in the surface cross-linking applied to the polymer particle group passing through the sieve having a mesh size of 212 ⁇ m or less is the water absorption characteristic under pressure. It can be seen that it greatly contributes to.
  • 10 Absorbent, 10a ... Water-absorbent resin particles, 10b ... Fiber layer, 20a, 20b ... Core wrap, 30 ... Liquid permeable sheet, 40 ... Liquid permeable sheet, 100 ... Absorbent article, 110 ... Measuring device, 112 ... Weight, 112a ... Disc, 112b ... Rod, 112c ... Cylindrical, 114 ... Cylindrical, 116 ... Wire mesh, 120 ... Particles to be measured, 130 ... Stainless steel, 140 ... Glass filter, 150 ... Filter paper.

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Citations (7)

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Publication number Priority date Publication date Assignee Title
WO1996028515A1 (fr) * 1995-03-09 1996-09-19 Nippon Shokubai Co., Ltd. Composition de resine absorbant le sang et articles absorbants
JP2004002891A (ja) * 1994-10-26 2004-01-08 Nippon Shokubai Co Ltd 吸水性樹脂の造粒粒子およびこれを含む吸収性物品ならびに吸水性樹脂の造粒粒子の製造方法
JP2005015787A (ja) * 2003-06-03 2005-01-20 Nippon Shokubai Co Ltd 吸水材の製造方法
JP2012506462A (ja) * 2008-10-22 2012-03-15 エボニック・ストックハウゼン・リミテッド・ライアビリティ・カンパニー 高吸収性ポリマー微粉を用いた高吸収性ポリマーゲルの生産のためのプロセス
JP2013540186A (ja) * 2010-10-06 2013-10-31 ビーエーエスエフ ソシエタス・ヨーロピア 熱的に表面後架橋された水吸収性ポリマー粒子の製法
US20140051813A1 (en) * 2010-11-30 2014-02-20 Lg Chem, Ltd Preparation method of superabsorbent polymer
WO2019143017A1 (ko) * 2018-01-16 2019-07-25 주식회사 엘지화학 고흡수성 수지의 제조 방법

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004002891A (ja) * 1994-10-26 2004-01-08 Nippon Shokubai Co Ltd 吸水性樹脂の造粒粒子およびこれを含む吸収性物品ならびに吸水性樹脂の造粒粒子の製造方法
WO1996028515A1 (fr) * 1995-03-09 1996-09-19 Nippon Shokubai Co., Ltd. Composition de resine absorbant le sang et articles absorbants
JP2005015787A (ja) * 2003-06-03 2005-01-20 Nippon Shokubai Co Ltd 吸水材の製造方法
JP2012506462A (ja) * 2008-10-22 2012-03-15 エボニック・ストックハウゼン・リミテッド・ライアビリティ・カンパニー 高吸収性ポリマー微粉を用いた高吸収性ポリマーゲルの生産のためのプロセス
JP2013540186A (ja) * 2010-10-06 2013-10-31 ビーエーエスエフ ソシエタス・ヨーロピア 熱的に表面後架橋された水吸収性ポリマー粒子の製法
US20140051813A1 (en) * 2010-11-30 2014-02-20 Lg Chem, Ltd Preparation method of superabsorbent polymer
WO2019143017A1 (ko) * 2018-01-16 2019-07-25 주식회사 엘지화학 고흡수성 수지의 제조 방법

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