WO2021075508A1

WO2021075508A1 - Absorbent article and auxiliary sheet

Info

Publication number: WO2021075508A1
Application number: PCT/JP2020/038951
Authority: WO
Inventors: 海紗生谷口
Original assignee: 住友精化株式会社
Priority date: 2019-10-18
Filing date: 2020-10-15
Publication date: 2021-04-22
Also published as: JPWO2021075508A1

Abstract

Disclosed is an absorbent article equipped with a strip-shaped water-absorbing core, an auxiliary sheet that assists with liquid absorption by the water-absorbing core, a liquid-impermeable sheet, and a liquid-permeable sheet. The liquid-impermeable sheet, water-absorbing core, and liquid-permeable sheet are disposed in that order. The auxiliary sheet is disposed between the impermeable sheet and the water-absorbing core and/or between the water-absorbing core and the liquid-permeable sheet. The auxiliary sheet has a swelling layer including water-absorbing resin particles. The swelling layer is provided along the longitudinal direction of the water-absorbing core on both ends of the lateral direction of the water-absorbing core, and the 10-second value of the swelling power of the water-absorbing resin particles contained in the swelling layer is 5 N or higher.

Description

Absorbent articles and auxiliary sheets

The present invention relates to an absorbent article and an auxiliary sheet.

Recently, an absorber having an absorbing layer capable of absorbing a liquid is used as an absorbent article for absorbing a liquid containing water as a main component such as urine.

For example, Patent Document 1 describes an absorbent article having a width direction and a front-rear direction, and having a top sheet, a back sheet, and a first absorbent body provided between them; a plurality of first absorbent bodies are provided. It contains a layer of sheet members, is configured to have a water-absorbent resin between the sheet members and no pulp fibers, and has end regions and a central region located between them on both sides in the width direction; An absorbent article in which a water-absorbent resin having a water absorption rate of 20 seconds or less by the vortex method is arranged in a partial region; and a water-absorbent resin having a water absorption rate of 40 seconds or more by the vortex method is arranged in a central region is disclosed. Has been done.

Japanese Unexamined Patent Publication No. 2015-150058

It is desirable that absorbent articles such as diapers can absorb more liquid when worn, and that liquid leakage to the outside of the absorbent articles is suppressed.

An object of the present invention is to provide an absorbent article having a high liquid absorption amount when worn by a user and in which liquid leakage is suppressed. It is also an object of the present invention to provide an auxiliary sheet which has a high liquid absorption amount when worn by a user and can provide an absorbent article in which liquid leakage is suppressed.

One aspect of the present invention includes a strip-shaped water absorbing core, an auxiliary sheet for assisting liquid absorption by the water absorbing core, a liquid impermeable sheet and a liquid permeable sheet, and includes a liquid impermeable sheet, a water absorbing core and a liquid permeable sheet. The sheets are arranged in this order, and the auxiliary sheet relates to an absorbent article which is arranged between the impermeable sheet and the water absorbing core and / or between the water absorbing core and the liquid permeable sheet. In the absorbent article, the auxiliary sheet has a swelling layer containing water-absorbing resin particles, and the swelling layers are provided on both ends of the water-absorbing core in the lateral direction along the longitudinal direction of the water-absorbing core. The 10-second value of the swelling power of the water-absorbent resin particles contained in the swelling layer is 5 N or more.

The 10-second value of the swelling power is measured by the swelling power test performed in the following order of i), ii), iii), iv) and v).
i) Prepare a cylinder with an inner diameter of 20 mm, which has openings at both ends and has a mesh mounted on one of the openings, with the cylinder standing vertically with the side on which the mesh is mounted facing down. 0.1 g of water-absorbent resin particles are uniformly sprayed on the mesh in the cylinder, and a cylindrical jig having a diameter of 19.5 mm is placed on the mesh.
ii) A glass filter having a thickness of 5 mm is placed in a horizontally installed petri dish, and the glass filter is impregnated with physiological saline to a position slightly below the upper surface thereof.
iii) An impermeable sheet is placed on the upper surface of a glass filter permeated with physiological saline, and a cylinder containing water-absorbent resin particles is erected vertically on the impermeable sheet with the mesh facing down.
iv) Remove the impermeable sheet and start water absorption by the water-absorbent resin particles.
v) The force for pushing up the cylindrical jig generated by the swelling of the water-absorbent resin particles at 10 seconds after the impermeable sheet is removed is measured by the load cell and recorded as a 10-second value of the swelling force.

Another aspect of the present invention is an auxiliary sheet used to assist the absorption of liquid in the water-absorbing core in an absorbent article provided with a water-absorbing core, which includes a swelling layer containing water-absorbing resin particles and is included in the swelling layer. The present invention relates to an auxiliary sheet in which the 10-second value of the swelling force of the water-absorbent resin particles is 5 N or more.

According to the present invention, it is possible to provide an absorbent article having a high liquid absorption amount in a wearing state of a user and suppressing liquid leakage.

Further, according to the auxiliary sheet of the present invention, for example, by arranging the absorbent article at a predetermined position, the absorbent article having a high liquid absorption amount in the wearing state of the user and the liquid leakage is suppressed is provided. be able to.

It is sectional drawing which shows an example of the auxiliary sheet. It is sectional drawing in the lateral direction which shows an example of an absorbent article. It is a top view which shows an example of the application pattern of the adhesive formed on the core wrap sheet. An example of a test absorbent article having swelling layers provided along the longitudinal direction on both ends of the water absorption core in the lateral direction on the user side on the water absorption core is shown, (A) is a top view, (B). ) Indicates a side view seen from the longitudinal direction. Another example of a test absorbent article having swelling layers provided along the longitudinal direction on both ends of the water absorption core in the lateral direction on the user side on the water absorption core is shown, and FIG. (B) shows a side view seen from the longitudinal direction. An example of a test absorbent article having a swelling layer provided along the outer circumference (edge) of the absorption core on the water absorption core on the user side is shown, (A) is a top view, and (B) is from the longitudinal direction. The side view is shown. An example of a test absorbent article having swelling layers provided along the longitudinal direction on both ends of the water absorption core in the lateral direction on the side opposite to the user side on the water absorption core is shown, and (A) shows an upper surface. FIG. 3B shows a side view seen from the longitudinal direction. An example of a test absorbent article having no swelling layer on the water absorption core is shown, (A) is a top view, and (B) is a side view seen from the longitudinal direction. An example of a test absorbent article having swelling layers provided along the longitudinal direction on both ends of the water absorption core in the lateral direction on the user side on the water absorption core is shown, (A) is a top view, (B). ) Indicates a side view seen from the longitudinal direction. It is a schematic diagram which shows the measuring apparatus of a swelling force test. It is a schematic diagram which shows the measuring apparatus of a crotch leakage test. It is a schematic diagram which shows the measuring apparatus of abdominal leakage and back leakage test.

Hereinafter, some embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

In this specification, "acrylic" and "methacryl" are collectively referred to as "(meth) acrylic". Similarly, "acrylate" and "methacrylate" are also referred to as "(meth) acrylate". In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step can be arbitrarily combined with the upper limit value or the lower limit value of the numerical range of another step. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" may include either A or B, or both. "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.

<Absorbent article>
The absorbent article according to one embodiment includes a water absorbing core, an auxiliary sheet for assisting liquid absorption by the water absorbing core, a liquid impermeable sheet, and a liquid permeable sheet. In the absorbent article, the liquid impermeable sheet, the water absorbing core and the liquid permeable sheet are arranged in this order. The auxiliary sheet is arranged between the impermeable sheet and the water absorbing core and / or between the water absorbing core and the liquid permeable sheet.

[Auxiliary sheet]
The auxiliary sheet includes a swelling layer containing water-absorbent resin particles. The auxiliary sheet is used in an absorbent article provided with a water-absorbing core to assist the liquid absorption of the water-absorbing core.

The 10-second value of the swelling force of the water-absorbent resin particles contained in the swelling layer, which is measured in the swelling force test performed in the order of i), ii), iii), iv) and v) below, is 5 N or more. ..

i) Prepare a cylinder with an inner diameter of 20 mm, which has openings at both ends and has a mesh mounted on one of the openings, with the cylinder standing vertically with the side on which the mesh is mounted facing down. 0.1 g of water-absorbent resin particles are uniformly sprayed on the mesh in the cylinder, and a cylindrical jig having a diameter of 19.5 mm is placed on the mesh.
ii) A glass filter having a thickness of 5 mm is placed in a horizontally installed petri dish, and the glass filter is impregnated with physiological saline to a position slightly below the upper surface thereof.
iii) An impermeable sheet is placed on the upper surface of a glass filter permeated with physiological saline, and a cylinder containing water-absorbent resin particles is erected vertically on the impermeable sheet with the mesh facing down.
iv) Remove the impermeable sheet and start water absorption by the water-absorbent resin particles.
v) The force to push up the cylindrical jig generated by the swelling of the water-absorbent resin particles at 10 seconds after removing the impermeable sheet is measured by the load cell, and the measured value at 10 seconds is the swelling force. Record as a 10-second value of. The 10-second value of the swelling force is specifically measured by the method described in Examples described later.

The 10-second value of the swelling power of the water-absorbent resin particles contained in the swelling layer may be 5N or more, 6N or more, 7N or more, 8N or more, 9N or more, 10N or more, or 11N or more, 20N or less, 18N or more. Hereinafter, it may be 16N or less, 14N or less, or 13N or less. The 10-second value of the swelling power of the water-absorbent resin particles contained in the swelling layer may be 5N or more and 20N or less, 5N or more and 18N or less, 5N or more and 16N or less, 5N or more and 14N or less, or 5N or more and 13N or less.

The 10-second value of the swelling force can be determined by, for example, changing the shape of the water-absorbent resin particles to adjust the specific surface area, performing surface treatment to make the surface of the water-absorbent resin hydrophilic, internal cross-linking and surface cross-linking. It can be controlled by adjusting the balance of the light and shade of the cross-linking density in one particle by the above.

In the absorbent article according to the present embodiment, first, when a liquid to be absorbed invades, the liquid is absorbed by the water absorption core and the auxiliary sheet. The water-absorbent resin particles having a swelling force of 10 seconds or more tend to swell more easily in the initial stage of liquid absorption, and the swelling layer containing such water-absorbent resin particles is formed in the lateral direction of the water-absorbing core. By arranging it along the longitudinal direction on both ends of the water-absorbing resin particles, the water-absorbent resin particles swollen in the initial stage of liquid absorption suppress the generation of liquid flow to the outside in the lateral direction due to the liquid that has subsequently invaded. As a result, it is considered that liquid leakage is suppressed in the wearing state of the user. So to speak, it is considered that gel layers that block the liquid flow are generated at both ends of the water absorption core to suppress liquid leakage in the lateral direction (width direction). However, the factors that suppress liquid leakage are not limited to the above factors.

The 60-second value of the swelling power of the water-absorbent resin particles contained in the swelling layer is 30 N or less, 20 N or less, 18 N or less, 15 N or less, 13 N or less, 10 N or less, or from the viewpoint of being more excellent in the liquid leakage suppressing effect in the used state. It may be 8N or less, 6N or more, or 7N or more. The 60-second value of the swelling power of the water-absorbent resin particles contained in the swelling layer is 6N or more and 30N or less, 6N or more and 20N or less, 6N or more and 18N or less, and 6N or more and 15N or less from the viewpoint of being more excellent in the liquid leakage suppressing effect in the used state. , 7N or more and 30N or less, 7N or more and 20N or less, 7N or more and 18N or less, or 7N or more and 15N or less.

The 60-second value of the swelling force is measured by the swelling force test performed in the order of i), ii), iii) and iv) described above and vi) below.
vi) The force to push up the cylindrical jig generated by the swelling of the water-absorbent resin particles 60 seconds after removing the impermeable sheet is measured by the load cell, and the measured value at 60 seconds later is the swelling force. Record as a 60-second value of. The 60-second value of the swelling force is specifically measured by the method described in Examples described later.

The 60-second value of the swelling force can be controlled, for example, by adjusting the balance of the density of the cross-linking in each particle due to the internal cross-linking and the surface cross-linking.

The water absorption amount of the physiological saline of the water-absorbent resin particles may be, for example, 20 to 80 g / g, 30 to 70 g / g, or 40 to 65 g / g. The water absorption rate (Vortex method) of the water-absorbent resin particles may be, for example, 1 to 70 seconds, 2 to 50 seconds, 2 to 25 seconds, or 2 to 10 seconds.

The water absorption amount and the water absorption rate of the physiological saline can be measured by the method described in Examples described later.

The shape of the water-absorbent resin particles according to the present embodiment is not particularly limited, and may be, for example, substantially spherical, crushed, or granular, and even if primary particles having these shapes are aggregated to form particles. Good.

The medium particle size of the water-absorbent resin particles may be 100 to 800 μm, 150 to 700 μm, 200 to 600 μm, or 250 to 500 μm. The medium particle size can be measured by the following method. From the top, JIS standard sieves have a mesh size of 600 μm, a mesh size of 500 μm, a mesh size of 425 μm, a mesh size of 300 μm, a mesh size of 250 μm, a mesh size of 180 μm, a mesh size of 150 μm, and a sieve. , Combine in the order of the saucer. 50 g of water-absorbent resin particles are placed in the best combined sieve, and the mixture is classified according to JIS Z8815 (1994) using a low-tap shaker (manufactured by Iida Seisakusho Co., Ltd.). After classification, the mass of the particles remaining on each sieve is calculated as a mass percentage with respect to the total amount to obtain the particle size distribution. 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 plotted on the logarithmic probability paper by integrating the particles on the sieve in order from the one having the largest particle size with respect to this particle size distribution. 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 is obtained as the medium particle size.

The water-absorbent resin particles 61a can include, for example, polymer particles formed by polymerizing a monomer containing an ethylenically unsaturated monomer. The polymer particles may be water-absorbent particles containing a polymer contained as a monomer unit derived from an ethylenically unsaturated monomer. The ethylenically unsaturated monomer may be a water-soluble monomer, and examples thereof include (meth) acrylic acid and salts thereof, 2- (meth) acrylamide-2-methylpropanesulfonic acid and its salts. Salt, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate, N, N-diethylaminoethyl (meth) ) Acrylate, N, N-diethylaminopropyl (meth) acrylate, and diethylaminopropyl (meth) acrylamide. When the ethylenically unsaturated monomer has an amino group, the amino group may be quaternized. The ethylenically unsaturated monomer may be used alone or in combination of two or more. Functional groups such as the carboxyl group and amino group of the above-mentioned monomers can function as functional groups capable of cross-linking in the surface cross-linking step described later.

The ethylenically unsaturated monomer may be used alone or in combination of two or more. The proportion of the polymer containing the ethylenically unsaturated monomer as a monomer unit in the polymer particles is 50 to 100% by mass, 60 to 100% by mass, and 70 to 100% by mass based on the mass of the polymer particles. , Or 80 to 100% by mass. The polymer particles may be particles containing a (meth) acrylic acid-based polymer containing at least one of (meth) acrylic acid or (meth) acrylate as a monomer unit. The total ratio of the monomer units derived from (meth) acrylic acid or (meth) acrylate in the (meth) acrylic acid-based polymer may be 70 to 100% by mass based on the mass of the polymer. , 90-100% by mass.

The water-absorbent resin particles 61a can be produced by a method including a step of polymerizing a monomer containing an ethylenically unsaturated monomer. Examples of the polymerization method include a reverse phase suspension polymerization method, an aqueous solution polymerization method, a bulk polymerization method, and a precipitation polymerization method. From the viewpoint of ensuring good water absorption characteristics of the obtained water-absorbent resin particles and facilitating control of the polymerization reaction, a reverse phase suspension polymerization method or an aqueous solution polymerization method may be applied. In the following, as a method for polymerizing an ethylenically unsaturated monomer, a reverse phase suspension polymerization method will be described as an example.

From the viewpoint of industrial availability, the ethylenically unsaturated monomer is at least one selected from the group consisting of (meth) acrylic acid and salts thereof, acrylamide, methacrylamide, and N, N-dimethylacrylamide. It may contain a compound of the species. The ethylenically unsaturated monomer may contain (meth) acrylic acid and a salt thereof, and at least one compound selected from the group consisting of acrylamide. From the viewpoint of further enhancing the water absorption property, the ethylenically unsaturated monomer may contain at least one compound selected from the group consisting of (meth) acrylic acid and salts thereof.

The ethylenically unsaturated monomer can be used in the polymerization reaction as an aqueous solution. The concentration of the ethylenically unsaturated monomer in the aqueous solution containing the ethylenically unsaturated monomer (hereinafter, simply referred to as "monomeric aqueous solution") is 20% by mass or more and the saturation concentration or less, 25 to 70% by mass, or 30. It may be up to 55% by mass. Examples of the water used in the aqueous solution include tap water, distilled water, ion-exchanged water and the like.

As the monomer for obtaining the water-absorbent resin particles, a monomer other than the above-mentioned ethylenically unsaturated monomer may be used. Such a monomer can be used, for example, by mixing with an aqueous solution containing the above-mentioned ethylenically unsaturated monomer. The amount of the ethylenically unsaturated monomer used may be 70 to 100 mol% with respect to the total amount of the monomer. The ratio of (meth) acrylic acid and a salt thereof may be 70 to 100 mol% with respect to the total amount of the monomer.

When the ethylenically unsaturated monomer has an acidic group, the acidic group may be neutralized with an alkaline neutralizer and then the monomer solution may be used in the polymerization reaction. The degree of neutralization of an ethylenically unsaturated monomer by an alkaline neutralizing agent increases the osmotic pressure of the obtained water-absorbent resin particles and further enhances the water absorption characteristics (water absorption amount, etc.). It may be 10-100 mol%, 50-90 mol%, or 60-80 mol% of the acidic group in the body. Examples of the 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 alone or in combination of two or more. The alkaline neutralizer may be used in the form of an aqueous solution to simplify the neutralization operation. Neutralization of the acidic group of the ethylenically unsaturated monomer can be performed, for example, by dropping an aqueous solution of sodium hydroxide, potassium hydroxide or the like into the above-mentioned monomer aqueous solution and mixing them.

In the reverse phase suspension polymerization method, an aqueous monomer solution is dispersed in a hydrocarbon dispersion medium in the presence of a surfactant, and an ethylenically unsaturated monomer is polymerized using a radical polymerization initiator or the like. Can be done. As the radical polymerization initiator, a water-soluble radical polymerization initiator can be used.

Examples of the surfactant include nonionic surfactants, anionic surfactants and the like. As the nonionic surfactant, sorbitan fatty acid ester and (poly) glycerin fatty acid ester (“(poly)” means both with and without the prefix of “poly”. The same shall apply hereinafter. ), Sucrose fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, sorbitol fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene himashi Examples thereof include oil, polyoxyethylene hydrogenated castor oil, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene polyoxypropyl alkyl ether, polyethylene glycol fatty acid ester and the like. Anionic surfactants include fatty acid salts, alkylbenzene sulfonates, alkylmethyl taurates, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene alkyl ether sulfonates, and polyoxyethylene alkyl ether phosphates. , And the phosphate ester of polyoxyethylene alkyl allyl ether and the like. The surfactant may be used alone or in combination of two or more.

From the viewpoint that the W / O type reverse phase suspension is in a good state, water-absorbent resin particles having a suitable particle size can be easily obtained, and industrially available, the surfactant is a sorbitan fatty acid ester. It may contain at least one compound selected from the group consisting of polyglycerin fatty acid ester and sucrose fatty acid ester. From the viewpoint of easily improving the water absorption characteristics of the obtained water-absorbent resin particles, sorbitan fatty acid ester (for example, sorbitan monolaurate) and / or sucrose fatty acid ester (for example, sucrose stearic acid ester) are used as the surfactant. Good. These surfactants may be used alone or in combination of two or more.

The amount of the surfactant may be 0.05 to 10 parts by mass, 0.08 to 5 parts by mass, or 0.1 to 3 parts by mass with respect to 100 parts by mass of the aqueous monomer solution.

In reverse phase suspension polymerization, a polymer-based dispersant may be used in combination with the above-mentioned surfactant. Examples of the polymer dispersant include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene / propylene copolymer, maleic anhydride-modified EPDM (ethylene / propylene / diene / terpolymer), and maleic anhydride. Modified polybutadiene, maleic anhydride / ethylene copolymer, maleic anhydride / propylene copolymer, maleic anhydride / ethylene / propylene copolymer, maleic anhydride / butadiene copolymer, polyethylene, polypropylene, ethylene / propylene copolymer Examples thereof include coalescence, oxidized polyethylene, oxidized polypropylene, oxidized ethylene / propylene copolymer, ethylene / acrylic acid copolymer, ethyl cellulose, ethyl hydroxyethyl cellulose and the like. The polymer-based dispersant may be used alone or in combination of two or more. From the viewpoint of excellent dispersion stability of the monomer, the polymer-based dispersant includes maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified ethylene / propylene copolymer, and maleic anhydride / ethylene copolymer. , Maleic anhydride / propylene copolymer, maleic anhydride / ethylene / propylene copolymer, polyethylene, polypropylene, ethylene / propylene copolymer, oxidized polyethylene, oxidized polypropylene, and oxidized ethylene / propylene copolymer It may be at least one selected from the group consisting of.

The amount of the polymer-based dispersant may be 0.05 to 10 parts by mass, 0.08 to 5 parts by mass, or 0.1 to 3 parts by mass with respect to 100 parts by mass of the aqueous monomer solution.

The hydrocarbon dispersion medium may contain at least one compound selected from the group consisting of chain aliphatic hydrocarbons having 6 to 8 carbon atoms and alicyclic hydrocarbons having 6 to 8 carbon atoms. Hydrocarbon dispersion media include chain aliphatic hydrocarbons such as n-hexane, n-heptane, 2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, and n-octane; cyclohexane. , Methylcyclohexane, cyclopentane, methylcyclopentane, trans-1,2-dimethylcyclopentane, cis-1,3-dimethylcyclopentane, trans-1,3-dimethylcyclopentane and other alicyclic hydrocarbons; benzene, Examples include aromatic hydrocarbons such as toluene and xylene. The hydrocarbon dispersion medium may be used alone or in combination of two or more.

From the viewpoint of industrial availability and stable quality, the hydrocarbon dispersion medium may contain at least one selected from the group consisting of n-heptane and cyclohexane. From the same viewpoint, as the mixture of the above-mentioned hydrocarbon dispersion medium, for example, commercially available ExxonHeptane (manufactured by ExxonMobil: containing 75 to 85% of n-heptane and isomeric hydrocarbons) is used. You may.

The amount of the hydrocarbon dispersion medium is 30 to 1000 parts by mass, 40 to 500 parts by mass, or 50 parts by mass with respect to 100 parts by mass of the monomer aqueous solution from the viewpoint of appropriately removing the heat of polymerization and easily controlling the polymerization temperature. It may be up to 300 parts by mass. When the amount of the hydrocarbon dispersion medium is 30 parts by mass or more, the polymerization temperature tends to be easily controlled. When the amount of the hydrocarbon dispersion medium is 1000 parts by mass or less, the productivity of polymerization tends to be improved, which is economical.

The radical polymerization initiator may be water-soluble. Examples of water-soluble radical polymerization initiators include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, and t-butyl cumylper. Peroxides such as oxides, t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxypivalate, hydrogen peroxide; 2,2'-azobis (2-amidinopropane) dihydrochloride , 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride, 2,2'-azobis [2- (N-allylamidino) propane] dihydrochloride, 2,2'-azobis [ 2- (2-imidazolin-2-yl) propane] 2 hydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} 2 hydrochloride, 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2'-azobis [2-methyl-N- (2-hydroxy) Ethyl) -propionamide], azo compounds such as 4,4'-azobis (4-cyanovaleric acid) can be mentioned. The radical polymerization initiator may be used alone or in combination of two or more. Radical polymerization initiators are potassium persulfate, ammonium persulfate, sodium persulfate, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl). ) Propane] 2 hydrochloride and 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} 2 hydrochloride, at least one selected from the group. There may be.

The amount of the radical polymerization initiator may be 0.00005 to 0.01 mol per 1 mol of the ethylenically unsaturated monomer. When the amount of the radical polymerization initiator used is 0.00005 mol or more, the polymerization reaction does not require a long time and is efficient. When the amount of the radical polymerization initiator is 0.01 mol or less, it is easy to suppress the occurrence of a rapid polymerization reaction.

The exemplified radical polymerization initiator can also be used as a redox polymerization initiator in combination with a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, and L-ascorbic acid.

At the time of the polymerization reaction, the aqueous monomer solution may contain a chain transfer agent. Examples of the chain transfer agent include hypophosphates, thiols, thiolic acids, secondary alcohols, amines and the like.

The monomer aqueous solution used for polymerization may contain a thickener in order to control the particle size of the water-absorbent resin particles. Examples of the thickener include hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose, polyacrylic acid, polyethylene glycol, polyacrylamide, polyethyleneimine, dextrin, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide and the like. If the stirring speed at the time of polymerization is the same, the higher the viscosity of the aqueous monomer solution, the larger the medium particle size of the obtained particles tends to be.

Cross-linking by self-cross-linking may occur during polymerization, but cross-linking may be further performed by using an internal cross-linking agent. When an internal cross-linking agent is used, it is easy to control the water absorption characteristics of the water-absorbent resin particles. The internal cross-linking agent is usually added to the reaction solution during the polymerization reaction. Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; Unsaturated polyesters obtained by reacting polyols with unsaturated acids (maleic acid, fumaric acid, etc.); bis (meth) acrylamides such as N, N'-methylenebis (meth) acrylamide; polyepoxides and (meth) Di or tri (meth) acrylic acid esters obtained by reacting with acrylic acid; di (meth) obtained by reacting polyisocyanate (tolylene diisocyanate, hexamethylene diisocyanate, etc.) with hydroxyethyl (meth) acrylate. ) Acrylic acid carbamil esters; compounds having two or more polymerizable unsaturated groups such as allylated starch, allylated cellulose, diallyl phthalate, N, N', N "-triallyl isocyanurate, divinylbenzene; Poly such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, polyglycerol polyglycidyl ether, etc. Glyceridyl compound; haloepoxy compound such as epichlorohydrin, epibromhydrin, α-methylepichlorohydrin; 2 reactive functional groups such as isocyanate compound (2,4-tolylene diisocyanate, hexamethylene diisocyanate, etc.) Examples thereof include compounds having more than one. The internal cross-linking agent may be used alone or in combination of two or more. The internal cross-linking agent may be a polyglycidyl compound or diglycidyl. It may be an ether compound. The internal cross-linking agent comprises at least one selected from the group consisting of (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether. It may be.

The amount of the internal cross-linking agent is not ethylenically from the viewpoint that the water-soluble property is suppressed by appropriately cross-linking the polymer obtained by the polymerization of the above-mentioned monomer aqueous solution, and a sufficient water absorption amount can be easily obtained. It may be 0 mmol or more, 0.01 mmol or more, 0.015 mmol or more, 0.020 mmol or more, or 0.1 mol or less, per 1 mol of saturated monomer.

An aqueous phase containing an ethylenically unsaturated monomer, a radical polymerization initiator, an internal cross-linking agent, etc., if necessary, and an oil containing a hydrocarbon-based dispersant and, if necessary, a surfactant, a polymer-based dispersant, etc. Reversed phase suspension polymerization can be carried out in an aqueous system in oil by heating with stirring in a state where the phases are mixed.

When performing reverse phase suspension polymerization, a monomer aqueous solution containing an ethylenically unsaturated monomer is used as a hydrocarbon dispersion medium in the presence of a surfactant (and, if necessary, a polymer-based dispersant). Disperse in. At this time, the timing of adding the surfactant, the polymer-based dispersant, or the like may be either before or after the addition of the aqueous monomer solution, as long as it is before the start of the polymerization reaction.

From the viewpoint of easily reducing the amount of the hydrocarbon dispersion medium remaining in the obtained water-absorbent resin, a surfactant is added after dispersing the monomer aqueous solution in the hydrocarbon dispersion medium in which the polymer-based dispersant is dispersed. The polymer may be further dispersed and then polymerized.

Reverse phase suspension polymerization can be carried out in one stage or in multiple stages of two or more stages. Reversed phase suspension polymerization may be carried out in two or three stages from the viewpoint of increasing productivity.

When reverse phase suspension polymerization is carried out in two or more stages, an ethylenically unsaturated monomer is added to the reaction mixture obtained in the first step polymerization reaction after the first step reverse phase suspension polymerization is carried out. It may be added and mixed, and the reverse phase suspension polymerization of the second and subsequent steps may be carried out in the same manner as in the first step. In the reverse phase suspension polymerization in each stage of the second and subsequent stages, in addition to the ethylenically unsaturated monomer, the above-mentioned radical polymerization initiator is used in the reverse phase suspension polymerization in each stage of the second and subsequent stages. Based on the amount of the ethylenically unsaturated monomer to be added, it may be added within the range of the molar ratio of each component to the above-mentioned ethylenically unsaturated monomer to carry out reverse phase suspension polymerization. In the reverse phase suspension polymerization in each stage after the second stage, an internal cross-linking agent may be used if necessary. When an internal cross-linking agent is used, it is added within the range of the molar ratio of each component to the above-mentioned ethylenically unsaturated monomer based on the amount of the ethylenically unsaturated monomer provided in each stage, and the suspension is reversed. Muddy polymerization may be carried out.

The temperature of the polymerization reaction varies depending on the radical polymerization initiator used, but by rapidly advancing the polymerization and shortening the polymerization time, the efficiency is improved and the heat of polymerization is easily removed to carry out the reaction smoothly. From the viewpoint, it may be 20 to 150 ° C. or 40 to 120 ° C. The reaction time is usually 0.5-4 hours. The completion of the polymerization reaction can be confirmed, for example, by stopping the temperature rise in the reaction system. As a result, the polymer of the ethylenically unsaturated monomer is usually obtained in the state of a hydrogel-like polymer.

After polymerization, cross-linking may be performed after polymerization by adding a cross-linking agent to the obtained hydrogel polymer and heating it. By performing cross-linking after the polymerization, the degree of cross-linking of the hydrogel polymer can be increased, whereby the water-absorbing characteristics of the water-absorbent resin particles can be further improved.

Examples of the cross-linking agent for performing post-polymerization cross-linking include polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; Compounds having two or more epoxy groups such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether; epichlorohydrin, epibromhydrin, α-methylepicrolhydrin and the like. Haloepoxy compounds; compounds having two or more isocyanate groups such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; oxazoline compounds such as 1,2-ethylene bisoxazoline; carbonate compounds such as ethylene carbonate; bis [N , N-di (β-hydroxyethyl)] hydroxyalkylamide compounds such as adipamide can be mentioned. Cross-linking agents for post-polymerization cross-linking are (poly) ethylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, and polyglycerol polyglycidyl ether. It may be a polyglycidyl compound such as. These cross-linking agents may be used alone or in combination of two or more.

The amount of the cross-linking agent used for post-polymerization cross-linking is 1 mol of the water-soluble ethylenically unsaturated monomer from the viewpoint of appropriately cross-linking the obtained hydrogel-like polymer to exhibit suitable water absorption characteristics. It may be 0 to 0.03 mol, 0 to 0.01 mol, or 0.00001 to 0.005 mol.

The cross-linking agent for post-polymerization cross-linking is added to the reaction solution after the polymerization reaction of the ethylenically unsaturated monomer. In the case of multi-stage polymerization, a cross-linking agent for post-polymerization cross-linking may be added after the multi-stage polymerization. Considering the fluctuation of water content due to heat generation during and after polymerization, retention due to process delay, opening of the system when adding a cross-linking agent, and addition of water due to addition of a cross-linking agent, the cross-linking agent for post-polymerization cross-linking is , From the viewpoint of water content (described later), it may be added in the region of [water content immediately after polymerization ± 3% by mass].

Subsequently, water is removed from the obtained hydrogel-like polymer. Drying to remove water gives polymer particles containing a polymer of ethylenically unsaturated monomers. Examples of the drying method include (a) a method of removing water by azeotropic distillation in a state where the hydrogel polymer is dispersed in a hydrocarbon dispersion medium, and (b) a method of taking out the hydrogel polymer by decantation and reducing the pressure. Examples thereof include a method of drying, and (c) a method of filtering the hydrogel polymer by a filter and drying under reduced pressure.

The particle size of the water-absorbent resin particles can be adjusted by adjusting the rotation speed of the stirrer during the polymerization reaction, or by adding a flocculant into the system after the polymerization reaction or in the early stage of drying. By adding a flocculant, the particle size of the obtained water-absorbent resin particles can be increased. As the flocculant, an inorganic flocculant can be used. Examples of the inorganic flocculant (for example, powdered inorganic flocculant) include silica, zeolite, bentonite, aluminum oxide, talc, titanium dioxide, kaolin, clay, hydrotalcite and the like. From the viewpoint of excellent aggregating effect, the aggregating agent may be at least one selected from the group consisting of silica, aluminum oxide, talc and kaolin.

In reverse phase suspension polymerization, a coagulant is previously dispersed in a hydrocarbon dispersion medium of the same type as that used in the polymerization or water, and then this is placed in a hydrocarbon dispersion medium containing a hydrogel polymer under stirring. May be mixed with.

The amount of the flocculant is 0.001 to 1 part by mass, 0.005 to 0.5 part by mass, or 0.01 to 0.2 with respect to 100 parts by mass of the ethylenically unsaturated monomer used for the polymerization. It may be a mass part. When the amount of the flocculant is within these ranges, it is easy to obtain water-absorbent resin particles having a desired particle size distribution.

The polymerization reaction can be carried out using various stirrers having stirring blades. As the stirring blade, a flat plate blade, a lattice blade, a paddle blade, a propeller blade, an anchor blade, a turbine blade, a Faudler blade, a ribbon blade, a full zone blade, a max blend blade and the like can be used. The flat plate blade has a shaft (stirring shaft) and a flat plate portion (stirring portion) arranged around the shaft. Further, the flat plate portion may have a slit or the like.

In the production of the water-absorbent resin particles 61a, cross-linking (surface cross-linking) of the surface portion of the hydrogel polymer may be carried out using a cross-linking agent in any of the drying step and subsequent steps. By performing surface cross-linking, it is easy to control the water absorption characteristics of the water-absorbent resin particles. The water content of the surface-crosslinked hydrogel polymer may be 5 to 50% by mass, 10 to 40% by mass, or 15 to 35% by mass. The water content (mass%) of the water-containing gel polymer is calculated by the following formula.
Moisture content = [Ww / (Ww + Ws)] x 100
Ww: Necessary when mixing a flocculant, a surface cross-linking agent, etc. to the amount obtained by subtracting the amount of water discharged to the outside of the system by the drying step from the amount of water contained in the monomer aqueous solution before polymerization in the entire polymerization step. The amount of water in the hydrogel polymer calculated by adding the amount of water used according to.

Ws: The amount of solid content calculated from the amount of materials such as ethylenically unsaturated monomers, cross-linking agents, and initiators that make up the hydrogel polymer.

Examples of the cross-linking agent (surface cross-linking agent) for performing surface cross-linking include compounds having two or more reactive functional groups. Examples of surface cross-linking agents include, for example, polyols such as ethylene glycol, propylene glycol, 1,4-butanediol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene. Polyglycidyl compounds such as glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, trimethylpropan triglycidyl ether (poly) propylene glycol polyglycidyl ether, (poly) glycerol polyglycidyl ether; Haloepoxy compounds such as chlorohydrin, epibromhydrin, α-methylepichlorohydrin; isocyanate compounds such as 2,4-tolylene diisocyanate, hexamethylene diisocyanate; 3-methyl-3-oxetane methanol, 3-ethyl- Oxetane compounds such as 3-oxetane methanol, 3-butyl-3-oxetane methanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, 3-butyl-3-oxetaneethanol; 1,2-ethylene Examples thereof include oxazoline compounds such as bisoxazoline; carbonate compounds such as ethylene carbonate; and hydroxyalkylamide compounds such as bis [N, N-di (β-hydroxyethyl)] adipamide. The surface cross-linking agent may be used alone or in combination of two or more. The surface cross-linking agent may be a polyglycidyl compound, and may be (poly) ethylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, and poly. It may be at least one selected from the group consisting of glycerol polyglycidyl ether.

The amount of the surface cross-linking agent used is 0.01 to 20 mmol, 0.05 to 10 mmol, based on 1 mol of the ethylenically unsaturated monomer used for the polymerization, from the viewpoint that suitable water absorption characteristics can be easily obtained. It may be 0.1-5 mmol, 0.15-3 mmol, or 0.2-1 mmol.

In the production of the water-absorbent resin particles 61a, the surface portion of the hydrogel polymer is treated (surface modification) with a surface modifier in either the drying step (moisture removal step) or a subsequent step. You may. The surface modification may be carried out, for example, before, during or after the surface cross-linking step. Surface modification may be carried out after surface cross-linking.

The surface modifier may be, for example, a surfactant such as a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant. For example, the HLB value of the nonionic surfactant used as the surface modifier may be, for example, 3 to 12, or 6 to 10. Examples of the nonionic surfactant include sorbitan fatty acid esters such as sorbitan monolaurate. The HLB value is measured by the Griffin method.

The amount of the surface modifier is 0.01 to 0.50 parts by mass, 0.02 to 0.40 parts by mass, or 0.04 with respect to 100 parts by mass of the ethylenically unsaturated monomer used for the polymerization. It may be ~ 0.30 parts by mass.

If necessary, after surface cross-linking and / or surface modification, water and a hydrocarbon dispersion medium can be distilled off from the hydrogel polymer to obtain polymer particles which are dry products. it can.

The water-absorbent resin particles 61a may be composed of only polymer particles, but further contain various additional components selected from, for example, a gel stabilizer, a metal chelating agent, a fluidity improver (lubricant), and the like. be able to. Additional components may be placed inside the polymer particles, on the surface of the polymer particles, or both. The additional component may be a fluidity improver (lubricant). The fluidity improver may contain inorganic particles. Examples of the inorganic particles include silica particles such as amorphous silica.

The water-absorbent resin particles 61a may contain a plurality of inorganic particles arranged on the surface of the polymer particles. For example, by mixing the polymer particles and the inorganic particles, the inorganic particles can be arranged on the surface of the polymer particles. The inorganic particles may be silica particles such as amorphous silica. When the water-absorbent resin particles 61a contain inorganic particles arranged on the surface of the polymer particles, the ratio of the amount of the inorganic particles to the mass of the polymer particles is 0.2% by mass or more, 0.5% by mass or more, It may be 1.0% by mass or more, 1.5% by mass or more, 5.0% by mass or less, or 3.5% by mass or less. The inorganic particles here usually have a minute size as compared with the size of the polymer particles. For example, the average particle size of the inorganic particles may be 0.1 to 50 μm, 0.5 to 30 μm, or 1 to 20 μm. The average particle size here can be a value measured by a dynamic light scattering method or a laser diffraction / scattering method.

FIG. 1 is a cross-sectional view showing a strip-shaped auxiliary sheet according to an embodiment. The auxiliary sheet 60 shown in FIG. 1 has a swelling layer 61 and two

sheet base materials

62a and 62b. The

sheet base materials

62a and 62b are arranged on both sides of the swelling layer 61. In other words, the swelling layer 61 is arranged inside the

sheet base materials

62a and 62b. The swelling layer 61 is held in shape by being sandwiched between the two

sheet base materials

62a and 62b. The

sheet base materials

62a and 62b may be two sheets, one folded sheet, or one bag.

The auxiliary sheet 60 may further have an adhesive 63a interposed between the sheet base material 62a and the swelling layer 61, and further has an adhesive 63b interposed between the sheet base material 62b and the swelling layer 61. You may have. The

adhesives

63a and 63b may be, for example, a water-based adhesive, a solvent-based adhesive, an elastic adhesive, an aerosol adhesive, a hot melt adhesive, or the like.

The length of the auxiliary sheet 60 in the longitudinal direction may be, for example, 20 cm or more, 22 cm or more, 24 cm or more, or 26 cm or more in a dry state, and is 60 cm or less, 50 cm or less, 40 cm or less, 38 cm or less, 36 cm or less, 34 cm or less. , Or 32 cm or less. Alternatively, the length of the auxiliary sheet 60 in the longitudinal direction may be 0.8 to 1.2 times the length of the water absorbing core included in the absorbent article in the dry state. , May be the same length.

The length of the auxiliary sheet 60 in the lateral direction may be, for example, 0.5 cm or more, 1 cm or more, 1.5 cm or more, or 2 cm or more in a dry state, and may be 6.5 cm or less, 5.5 cm or less, 4. It may be 5 cm or less, 3.5 cm or less, 3.0 cm or less, or 2.5 cm or less.

Further, the length of the region where the swelling layer 61 exists in the auxiliary sheet 60 in the lateral direction is less than 1 / 2W with respect to the width W of the water absorption core included in the absorbent article in the dry state, and the water absorption core. Even if it is placed at both ends in the lateral direction, it does not cover the entire water absorption core.

The thickness of the auxiliary sheet 60 may be, for example, 3.0 mm or less, 2.5 mm or less, 2.0 mm or less, or 1.8 mm or less in a dry state, and is 0.1 mm or more, 0.3 mm or more, or 0. It may be 5.5 mm or more. The thickness can be measured using, for example, a dial thickness gauge JB manufactured by Ozaki Seisakusho Co., Ltd. (the stylus is made of aluminum having a diameter of 50 mm).

In the auxiliary sheet 60, the amount of water-absorbent resin particles (mass of water-absorbent resin particles per unit area) is 10 to 100 g / m ² , 15 to 60 g / m ² , or 18 to 45 g / m ^2. Good.

The swelling layer 61 has the water-absorbent resin particles 61a according to the above-described embodiment and the fiber layer 61b containing a fibrous material. The swelling layer 61 does not have to have the fiber layer 61b. The content of the water-absorbent resin particles in the swelling layer may be 70 to 100% by mass, 80 to 100% by mass, or 90 to 100% by mass based on the mass of the swelling layer 61.

The thickness of the swelling layer 61 may be, for example, 2.0 mm or less, 1.5 mm or less, 1.0 mm or less, or 0.8 mm or less in a dry state, and is 0.1 mm or more, or 0.3 mm or more. You may. The mass per unit area of the swelling layer 61 may be 100 g / m ² or less, 80 g / m ² or less, 60 g / m ² or less, or 40 g / m ² or less, 10 g / m ² or more, 20 g / m. ^It ^{may be 2} or more, or 25 g / m 2 or more.

The fibrous material constituting the fiber layer 61b can be, for example, a cellulosic fiber, a synthetic fiber, or a combination thereof. Examples of cellulosic fibers include crushed wood pulp, cotton, cotton linters, rayon and cellulosic acetate. Examples of synthetic fibers include polyamide fibers, polyester fibers, and polyolefin fibers. The fibrous material may be hydrophilic fibers (for example, pulp).

The swelling layer 61 may further contain inorganic particles (for example, amorphous silica), a deodorant, an antibacterial agent, a fragrance, and the like.

The

sheet base materials

62a and 62b may be, for example, a non-woven fabric, a tissue, or the like. The two

sheet base materials

62a and 62b can be the same or different non-woven fabrics. The non-woven fabric may be a non-woven fabric composed of short fibers (that is, staples) (short-fiber non-woven fabric) or a non-woven fabric composed of long fibers (that is, filaments) (long-fiber non-woven fabric). The staples may generally have a fiber length of several hundred mm or less.

The non-woven fabrics used as the

sheet base materials

62a and 62b are thermal-bonded non-woven fabrics, air-through non-woven fabrics, resin-bonded non-woven fabrics, spunbonded non-woven fabrics, melt-blown non-woven fabrics, air-laid non-woven fabrics, spunlaced non-woven fabrics, point-bonded non-woven fabrics, or two or more kinds selected from these. It may be a laminate containing a non-woven fabric.

The non-woven fabric used as the

sheet base materials

62a and 62b can be a non-woven fabric formed of synthetic fibers, natural fibers, or a combination thereof. Examples of synthetic fibers include polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN), polyamides such as nylon, and Examples thereof include fibers containing a synthetic resin selected from rayon. Examples of natural fibers include fibers containing cotton, silk, hemp, or pulp (cellulose). The fibers forming the non-woven fabric may be polyolefin fibers, polyester fibers or a combination thereof. The

sheet base materials

62a and 62b may be tissues.

The tissues used as the

sheet base materials

62a and 62b may be natural fibers or natural fibers mixed with synthetic fibers. The mass per unit area of the tissue may be ^{16 ± 2 g / m 2.} The thickness of the tissue may be 0.12 ± 0.02 mm.

The

sheet base materials

62a and 62b may have a main surface wider than the main surface of the swelling layer 61. That is, the outer edges of the

sheet base materials

62a and 62b may extend around the swelling layer 61. The

sheet base materials

62a and 62b may be adhered to each other at the outer edge portion extending around the swelling layer 61.

The auxiliary sheet 60 can be obtained, for example, by sandwiching the swelling layer 61 between the

sheet base materials

62a and 62b and pressurizing the formed structure while heating it as necessary. If necessary, the

adhesives

63a and 63b are arranged between the

sheet base materials

62a and 62b and the swelling layer 61.

The auxiliary sheet 60 is used, for example, for producing various absorbent articles. Examples of absorbent articles include diapers (eg paper diapers), toilet training pants, incontinence pads, sanitary materials (sanitary napkins, tampons, etc.), sweat pads, pet sheets, toilet components, and animal waste treatment materials. Can be mentioned.

[Absorbent article]
FIG. 2 is a cross-sectional view of the absorbent article according to the embodiment in the lateral direction. The absorbent article 100 shown in FIG. 2 includes a strip-shaped water absorbing core 50, an auxiliary sheet 60, a liquid permeable sheet 30, and a liquid permeable sheet 40.

In the absorbent article 100 shown in FIG. 2, the auxiliary sheet 60 provided with the swelling layer 61 is arranged between the water absorbing core 50 and the liquid permeable sheet 30. The auxiliary sheet 60 may be arranged between the impermeable sheet 40 and the water absorbing core 50 instead of being arranged between the water absorbing core 50 and the liquid permeable sheet 30. Further, the auxiliary sheet 60 may be arranged between the water absorption core 50 and the liquid permeable sheet 30, and between the water absorption core 50 and the liquid permeable sheet 30. The auxiliary sheet may be arranged between the water absorption core and the liquid permeable sheet from the viewpoint of being more excellent in the liquid leakage suppressing effect in the use state.

The auxiliary sheet 60 shown in FIG. 2 is arranged on the main surface of the user side when the water absorption core 50 is worn by the user, but is opposite to the user side (outside) when the water absorption core 50 is worn by the user. ), And may be arranged on both the user side and the outer side.

The auxiliary sheet 60 has a swelling layer 61 containing water-absorbent resin particles 61a. The swelling layer 61 is provided on both ends of the water absorption core 50 in the lateral direction along the longitudinal direction of the water absorption core 50. In the auxiliary sheet 60 including the swelling layer 61 and the

sheet base materials

62a and 62b, the swelling layer on one end of the water absorption core and the swelling layer on the other end are provided on separate sheet base materials. It may be provided on one sheet base material.

The swelling layer 61 in the auxiliary sheet 60 may be further provided on both ends of the water absorption core 50 in the longitudinal direction along the lateral direction of the water absorption core 50. In this case, one auxiliary sheet having a swelling layer 61 provided along the outer circumference (edge) on the end of the water absorption core 50 can be used.

The absorbent article 100 has water-absorbent resin particles having a 10-second value of the above-mentioned swelling force of 5 N or more between the swelling layers provided along the longitudinal direction on both ends of the water-absorbing core 50 in the lateral direction. It has an area that does not include it. In other words, the absorbent article 100 has a region on the central portion of the water absorbing core 50 that does not contain the water absorbing resin particles having the above-mentioned 10-second value of the swelling force of 5 N or more. For example, a substance other than the water-absorbent resin particles having a 10-second value of the swelling force of 5 N or more may be arranged in the region, if necessary, and the region may be a void.

The water absorption core 50 has an absorption layer 10 and two

core wrap sheets

20a and 20b. The

core wrap sheets

20a and 20b are arranged on both sides of the absorption layer 10. In other words, the absorbent layer 10 is arranged inside the

core wrap sheets

20a and 20b, and is held in shape by being sandwiched between the two core wrap sheets. The

core wrap sheets

20a and 20b may be separate sheets, one folded sheet, or one bag body. However, the water absorption core 50 does not have to have one or both of the two

core wrap sheets

20a and 20b. For example, the core wrap sheet 20a may not be arranged between the absorption layer 10 and the auxiliary sheet 60. When the core wrap sheet is not arranged between the absorption layer 10 and the auxiliary sheet 60, for example, the absorption layer 10 is sandwiched between one core wrap sheet 20b and the auxiliary sheet 60. It is kept in shape.

The water absorption core 50 may further have an adhesive interposed between the core wrap sheet 20a and the absorption layer 10, and further has an adhesive interposed between the core wrap sheet 20b and the absorption layer 10. May be. An adhesive layer may be interposed between the

core wrap sheets

20a and 20b on both sides and the absorption layer 10. FIG. 3 is a plan view showing an example of an adhesive application pattern formed on the core wrap sheet. The adhesive 21 shown in FIG. 3 forms a coating pattern composed of a plurality of linear portions arranged at intervals on the core wrap sheet 20a. The coating pattern of the adhesive 21 may be linear, curved, dot-shaped, or a combination thereof. The adhesive may be, for example, a water-based adhesive, a solvent-based adhesive, or a hot-melt adhesive.

The absorption layer 10 has water-absorbent resin particles 10a and a fiber layer 10b containing a fibrous material. The absorption layer 10 does not have to have the fiber layer 10b. The content of the water-absorbent resin particles in the absorption layer may be 70 to 100% by mass, 80 to 100% by mass, or 90 to 100% by mass based on the mass of the absorption layer 10.

The water-absorbent resin particles 10a may be particles containing a polymer containing an ethylenically unsaturated monomer as a monomer unit. The ethylenically unsaturated monomer may be a water-soluble monomer, and examples thereof include (meth) acrylic acid and salts thereof, 2- (meth) acrylamide-2-methylpropanesulfonic acid and its salts. Salt, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate, N, N-diethylaminoethyl (meth) ) Acrylate, N, N-diethylaminopropyl (meth) acrylate, and diethylaminopropyl (meth) acrylamide. The ethylenically unsaturated monomer may be used alone or in combination of two or more. When the ethylenically unsaturated monomer has a functional group such as a carboxyl group or an amino group, they can function as a functional group for cross-linking the polymer. The water-absorbent resin particles may be particles containing a polymer containing at least one of (meth) acrylic acid or a salt of (meth) acrylic acid as a monomer unit.

The water-absorbent resin particles 10a can be produced, for example, by a method including polymerizing a monomer containing an ethylenically unsaturated monomer. The polymerization method of the monomer can be selected from, for example, a reverse phase suspension polymerization method, an aqueous solution polymerization method, a bulk polymerization method, and a precipitation polymerization method. From the viewpoint of ensuring good water absorption characteristics of the water-absorbent resin particles and easily controlling the polymerization reaction, a reverse phase suspension polymerization method or an aqueous solution polymerization method may be adopted.

The polymer constituting the water-absorbent resin particles 10a may be a crosslinked polymer. In this case, the polymer may be crosslinked by self-crosslinking, cross-linking by reaction with a cross-linking agent, or both. The water-absorbent resin particles may be surface-crosslinked by cross-linking at least the polymer of the surface layer portion with a cross-linking agent.

The water-absorbent resin particles 10a may contain various additional components in addition to the polymer of the ethylenically unsaturated monomer. Examples of additional ingredients include gel stabilizers, metal chelating agents, and fluidity improvers (lubricants). Additional components may be placed inside the polymer particles, including the polymer, on the surface of the polymer particles, or both. The additional component may be a fluidity improver (lubricant). The fluidity improver may contain inorganic particles. Examples of the inorganic particles include silica particles such as amorphous silica.

The shape of the water-absorbent resin particles 10a may be, for example, substantially spherical, crushed or granular, and particles having these shapes may be aggregated. The medium particle size of the water-absorbent resin particles may be 250 to 850 μm, 300 to 700 μm, or 300 to 600 μm. As for the water absorption characteristics of the water-absorbent resin particles 10a, for example, the water absorption amount of the physiological saline may be 20 to 80 g / g, 30 to 70 g / g, or 40 to 65 g / g.

The 10-second value of the gel swelling force of the water-absorbent resin particles 10a may be less than 5N, may be 4N or less, and may be 0N or more from the viewpoint of further enhancing the liquid leakage suppressing effect in the wearing state of the user. You can. The 60-second value of the gel swelling force of the water-absorbent resin particles 10a is 20 N or less, 16 N or less, 12 N or less, 8 N or less, less than 7 N, or 5 N or less from the viewpoint of further enhancing the liquid leakage suppressing effect in the wearing state of the user. It may be 0N or more, or 2N or more. The method for measuring the 10-second value and the 60-second value of the gel swelling force is as described above.

The thickness of the absorption layer 10 may be, for example, 20 mm or less, 15 mm or less, 10 mm or less, 5 mm or less, 4 mm or less, or 3 mm or less, even if it is 0.1 mm or more, or 0.3 mm or more in a dry state. Good. The mass per unit area of the absorption layer 10 may be 1000 g / m ² or less, 800 g / m ² or less, or 600 g / m ² or less, 100 g / m ² or more, or 200 g / m ² or more. May be good.

The fibrous material constituting the fiber layer 10b can be, for example, a cellulosic fiber, a synthetic fiber, or a combination thereof. Examples of cellulosic fibers include crushed wood pulp, cotton, cotton linters, rayon and cellulosic acetate. Examples of synthetic fibers include polyamide fibers, polyester fibers, and polyolefin fibers. The fibrous material may be hydrophilic fibers (for example, pulp).

The absorption layer 10 may further contain inorganic particles (for example, amorphous silica), a deodorant, an antibacterial agent, a fragrance, and the like. When the water-absorbent resin particles 10a contain inorganic particles, the absorption layer 10 may contain inorganic particles in addition to the inorganic particles in the water-absorbent resin particles 10a.

The

core wrap sheets

20a and 20b may be, for example, a non-woven fabric. The two

core wrap sheets

20a and 20b can be the same or different non-woven fabrics. The non-woven fabric may be a non-woven fabric composed of short fibers (that is, staples) (short-fiber non-woven fabric) or a non-woven fabric composed of long fibers (that is, filaments) (long-fiber non-woven fabric). The staples may generally have a fiber length of several hundred mm or less.

The

core wrap sheets

20a and 20b are laminated including a thermal bond non-woven fabric, an air-through non-woven fabric, a resin bond non-woven fabric, a spunbond non-woven fabric, a melt blow non-woven fabric, an air-laid non-woven fabric, a spunlace non-woven fabric, a point bond non-woven fabric, or two or more kinds of non-woven fabrics selected from these. It can be a body.

The non-woven fabric used as the

core wrap sheets

20a and 20b can be a non-woven fabric formed of synthetic fibers, natural fibers, or a combination thereof. Examples of synthetic fibers include polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN), polyamides such as nylon, and Examples thereof include fibers containing a synthetic resin selected from rayon. Examples of natural fibers include fibers containing cotton, silk, hemp, or pulp (cellulose). The fibers forming the non-woven fabric may be polyolefin fibers, polyester fibers or a combination thereof. The

core wrap sheets

20a and 20b may be tissues.

The water-absorbing core 50 is sandwiched between, for example, the water-absorbent resin particles 10a or a mixture containing the water-absorbent resin particles 10a and the fibrous material and the

core wrap sheets

20a and 20b, and the formed structure is heated as necessary. It can be obtained by the method of pressurizing. If necessary, an adhesive is placed between the

core wrap sheets

20a and 20b and the water-absorbent resin particles 10a or a mixture containing the same.

The water-absorbing core 50 includes a water-absorbing core in which the core wrap sheet 20a, the water-absorbent resin particles 10a, the absorbent layer 10 composed of the fiber layer 10b, and the core wrap sheet 20b are arranged in this order, and substantially the entire fiber layer. It may be in the form of a sheet that does not include it. The water absorption core may include a plurality of (for example, two) absorption layers. When the water absorption core includes a plurality of absorption layers, a core wrap sheet may be arranged between the absorption layers. The water-absorbent resin particles contained in the plurality of absorption layers may be of the same type or different types. The mass and thickness per unit area of each of the plurality of absorption layers may be the same or different.

The liquid permeable sheet 30 is arranged at the position of the outermost layer on the side where the liquid to be absorbed enters. The liquid permeable sheet 30 is arranged on the outside of the core wrap sheet 20b in contact with the core wrap sheet 20b. The liquid permeable sheet 40 is arranged at the position of the outermost layer on the side opposite to the liquid permeable sheet 30 in the absorbent article 100. The liquid impermeable sheet 40 is arranged on the outside of the core wrap sheet 20a in a state of being in contact with the core wrap sheet 20a. The liquid permeable sheet 30 and the liquid permeable sheet 40 have a main surface wider than the main surface of the water absorbing core 50, and the outer edges of the liquid permeable sheet 30 and the liquid permeable sheet 40 are an absorbing layer. It extends around 10 and the

core wrap sheets

20a and 20b. However, the magnitude relationship of the absorbent layer 10, the

core wrap sheets

20a and 20b, the auxiliary sheet 60, the liquid permeable sheet 30, and the liquid permeable sheet 40 is appropriately adjusted according to the use of the absorbent article and the like.

The liquid permeable sheet 30 may be a non-woven fabric. The non-woven fabric used as the liquid permeable sheet 30 may have appropriate hydrophilicity from the viewpoint of the liquid absorption performance of the absorbent article. From this point of view, the liquid permeable sheet 30 is obtained from the pulp and paper test method No. 1 by the Paper and Pulp Technology Association. A non-woven fabric having a hydrophilicity of 5 to 200 measured according to the measuring method of 68 (2000) may be used. The hydrophilicity of the non-woven fabric may be 10 to 150. Pulp and paper test method No. For details of 68, for example, WO2011 / 086843 can be referred to.

The non-woven fabric having hydrophilicity may be formed of fibers showing appropriate hydrophilicity such as rayon fiber, or obtained by hydrophilizing a hydrophobic chemical fiber such as polyolefin fiber or polyester fiber. It may be formed of rayon fibers. Examples of a method for obtaining a non-woven fabric containing hydrophobic chemical fibers that have been hydrophilized include a method for obtaining a non-woven fabric by a spunbond method using a mixture of hydrophobic chemical fibers and a hydrophilic agent, and hydrophobic chemistry. Examples thereof include a method of accommodating a hydrophilic agent when producing a spunbonded non-woven fabric from fibers, and a method of impregnating a spunbonded non-woven fabric obtained by using hydrophobic chemical fibers with a hydrophilicizing agent. Hydrophilic agents include anionic surfactants such as aliphatic sulfonates and higher alcohol sulfates, cationic surfactants such as quaternary ammonium salts, polyethylene glycol fatty acid esters, polyglycerin fatty acid esters, and sorbitan fatty acids. Nonionic surfactants such as esters, silicone-based surfactants such as polyoxyalkylene-modified silicones, and stain-releasing agents made of polyester-based, polyamide-based, acrylic-based, and urethane-based resins are used.

The amount of texture (mass per unit area) of the non-woven fabric used as the liquid permeable sheet 30 is from the viewpoint of imparting good liquid permeability, flexibility, strength and cushioning property to the absorbent article, and the liquid of the absorbent article. From the viewpoint of increasing the permeation rate, it may be 5 to 200 g / m ² , 8 to 150 g / m ² , or 10 to 100 g / m ² . The thickness of the liquid permeable sheet 30 may be 20 to 1400 μm, 50 to 1200 μm, or 80 to 1000 μm.

The liquid impermeable sheet 40 prevents the liquid absorbed by the absorption layer 10 or the swelling layer 61 from leaking to the outside from the liquid impermeable sheet 40 side. The liquid impermeable sheet 40 may be a resin sheet or a non-woven fabric. The resin sheet may be a sheet made of a synthetic resin such as polyethylene, polypropylene, or polyvinyl chloride. The non-woven fabric may be a spunbond / meltblow / spunbond (SMS) non-woven fabric in which a water-resistant melt-blow non-woven fabric is sandwiched between high-strength spunbond non-woven fabrics. Further, the liquid permeable sheet 40 may be a composite sheet of a resin sheet and a non-woven fabric (for example, a spunbonded non-woven fabric or a spunlaced non-woven fabric). The liquid impermeable sheet 40 may have breathability from the viewpoint that stuffiness at the time of wearing is reduced and discomfort given to the wearer can be reduced. As the liquid impermeable sheet 40 having breathability, for example, a sheet of low density polyethylene (LDPE) resin can be used.

From the viewpoint of ensuring flexibility so as not to impair the wearing feeling of the absorbent article, the basis weight (mass per unit area) of the liquid impermeable sheet 40 is 5 to 100 g / m ² or 10 to 50 g / m ^2. It may be.

The absorbent article 100 is, for example, in an absorbent article including a strip-shaped water absorbing core 50, a liquid permeable sheet 30, and a liquid impermeable sheet 40, and the auxiliary sheet 60 is a liquid impermeable sheet 40 and a water absorbing core 50. It can be manufactured by a method including placing between and / or between the water absorbing core 50 and the liquid permeable sheet 30. The liquid permeable sheet 40, the water absorbing core 50 and the liquid permeable sheet 30 are provided in this order, and the auxiliary sheet 60 is provided between the liquid permeable sheet 40 and the water absorbing core 50 and / or between the water absorbing core and the liquid permeable sheet 30. The laminate arranged between and is pressurized if necessary. The structural units may be bonded with an adhesive.

<Method of suppressing liquid leakage>
According to the present embodiment, it is possible to provide a method for suppressing liquid leakage using the auxiliary sheet according to the present embodiment. The method for suppressing liquid leakage according to the present embodiment is to use an auxiliary sheet having the swelling layer in an absorbent article provided with a strip-shaped water absorbing core, a liquid impermeable sheet and a liquid permeable sheet in the lateral direction of the water absorbing core. The swelling layer is arranged along the longitudinal direction on both ends of the swelling layer.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Production Example 1 Water-absorbent resin particles a
Inner diameter 11 cm, contents equipped with a reflux condenser, a dropping funnel, a nitrogen gas introduction pipe, and a stirrer (a stirrer blade having two stages of four inclined paddle blades (surface treated with fluororesin) with a blade diameter of 5 cm). A round-bottomed cylindrical separable flask with a stack of 2 L and four side wall baffles (baffle length: 10 cm, baffle width: 7 mm) was prepared. To this flask, 451.4 g of n-heptane as a hydrocarbon dispersion medium was added, and 1.288 g of sorbitan monolaurate (Nonion LP-20R, HLB value: 8.6, manufactured by NOF CORPORATION) was added as a surfactant. The mixture was obtained by addition. The sorbitan monolaurate was dissolved in n-heptane by heating the mixture to 50 ° C. while stirring at a stirring speed of 300 rpm, and then the mixture was cooled to 40 ° C.

Next, 92.0 g (acrylic acid: 1.03 mol) of an 80.5 mass% acrylic acid aqueous solution was placed in an Erlenmeyer flask having an internal volume of 500 mL. Subsequently, 147.7 g of a 20.9 mass% sodium hydroxide aqueous solution was added dropwise from the outside while cooling with ice to neutralize the acrylic acid, thereby obtaining an aqueous solution of a partially neutralized acrylic acid. Next, 0.1012 g (0.374 mmol) of potassium persulfate as a water-soluble radical polymerization initiator was added to the acrylic acid partially neutralized aqueous solution and then dissolved to prepare a monomer aqueous solution.

After adding the above-mentioned monomer aqueous solution to the above-mentioned separable flask, the inside of the system was sufficiently replaced with nitrogen. Then, the flask was immersed in a water bath at 70 ° C. and held for 60 minutes to complete the polymerization while stirring at a rotation speed of 700 rpm of the stirrer to obtain a hydrogel polymer.

Then, while stirring at a stirring speed of 1000 rpm, amorphous silica (Oriental Silicas Corporation, oriental silicas corporation, etc.) was added to the polymer solution containing the produced hydrogel polymer, n-heptane and a surfactant as a powdery inorganic flocculant. A dispersion obtained by previously dispersing 0.092 g of Toxile NP-S) in 100 g of n-heptane was added and then mixed for 10 minutes. Then, the flask containing the reaction solution was immersed in an oil bath at 125 ° C., and 98.0 g of water was extracted from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Then, 4.14 g (ethylene glycol diglycidyl ether: 0.475 mmol) of 2% by mass of an ethylene glycol diglycidyl ether aqueous solution was added as a surface cross-linking agent, and the mixture was maintained at an internal temperature of 83 ± 2 ° C. for 2 hours.

Next, a surfactant solution in which 0.074 g of sorbitan monolaurate (trade name: Nonion LP-20R, HLB value 8.6, manufactured by Nichiyu Co., Ltd.), which is a surfactant, was dissolved in 6.62 g of n-heptane was added. Added in a flask.

Then, water and n-heptane were heated in an oil bath at 125 ° C. to evaporate, and dried until almost no evaporation from the system was distilled off to obtain a dried product of polymer particles. The polymer particles were passed through a sieve having an opening of 850 μm to obtain 90.1 g of water-absorbent resin particles a. The medium particle size of the water-absorbent resin particles a was 352 μm.

Production Example 2 Water-absorbent resin particles b
104.0 g of water was extracted from the system by azeotropic distillation, and the surface cross-linking agent was changed to 8.28 g of a 2 mass% ethylene glycol diglycidyl ether aqueous solution (ethylene glycol diglycidyl ether: 0.951 mmol). 90.3 g of water-absorbent resin particles b were obtained in the same manner as in Production Example 1 except for the above. The medium particle size of the water-absorbent resin particles b was 420 μm.

Production Example 3 Water-absorbent resin particles c
A round-bottomed cylindrical separable flask with an inner diameter of 11 cm and a volume of 2 L equipped with a reflux condenser, a dropping funnel, a nitrogen gas introduction pipe, and a stirring blade having four inclined paddle blades with a blade diameter of 5 cm in two stages as a stirrer. Got ready. To this flask, take 293 g of n-heptane as a hydrocarbon dispersion medium, add 0.736 g of a maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals Co., Ltd., High Wax 1105A) as a polymer-based dispersant, and stir. The temperature was raised to 80 ° C. to dissolve the dispersant, and then cooled to 50 ° C.

In a beaker having an internal volume of 300 mL, 92.0 g (1.03 mol) of an 80.5 mass% acrylic acid aqueous solution as a water-soluble ethylenically unsaturated monomer was placed, and while being cooled from the outside, 20.9 mass% was added. After adding 147.7 g of an aqueous sodium hydroxide solution to neutralize 75 mol%, 0.092 g of hydroxylethyl cellulose (Sumitomo Seika Co., Ltd., HECAW-15F) as a thickener, as a water-soluble radical polymerization initiator. 0.0736 g (0.272 mmol) of potassium persulfate and 0.010 g (0.057 mmol) of ethylene glycol diglycidyl ether as an internal cross-linking agent were added and dissolved to prepare a first-stage monomer aqueous solution.

Then, the first-stage monomer aqueous solution prepared above was added to the separable flask, and after stirring for 10 minutes, 6.62 g of n-heptane was added as a surfactant to the sucrose stearic acid ester of HLB3. Mitsubishi Chemical Foods Co., Ltd., Ryoto Sugar Ester S-370) 0.736 g of a surfactant solution dissolved by heating is further added, and the inside of the system is sufficiently filled with nitrogen while stirring at a stirring speed of 500 rpm. After the replacement, the flask was immersed in a water bath at 70 ° C. to raise the temperature, and the polymerization was carried out for 60 minutes to obtain a first-stage polymerized slurry solution.

128.8 g (1.44 mol) of an 80.5 mass% acrylic acid aqueous solution as a water-soluble ethylenically unsaturated monomer was placed in a beaker having an internal volume of 500 mL, and 27 mass% sodium hydroxide was cooled from the outside. After 159.0 g of the aqueous solution was added dropwise to neutralize 75 mol%, 0.090 g (0.333 mmol) of potassium persulfate was used as the water-soluble radical polymerization initiator, and ethylene glycol diglycidyl ether was used as the internal cross-linking agent. 0116 g (0.067 mmol) was added and dissolved to prepare a second-stage monomer aqueous solution.

After cooling the inside of the separable flask system to 25 ° C. while stirring at a stirring speed of 1000 rpm, the entire amount of the monomer aqueous solution in the second stage is added to the polymerized slurry liquid in the first stage. After adding and replacing the inside of the system with nitrogen for 30 minutes, the flask was again immersed in a water bath at 70 ° C. to raise the temperature, and the polymerization reaction was carried out for 60 minutes to obtain a hydrogel polymer.

After the polymerization, 0.589 g of a 45% by mass diethylenetriamine-5 sodium acetate aqueous solution was added to the obtained hydrogel polymer under stirring. Then, the flask was immersed in an oil bath set at 125 ° C., and 257.2 g of water was extracted from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Then, 4.42 g (0.507 mmol) of a 2% by mass ethylene glycol diglycidyl ether aqueous solution was added to the flask as a surface cross-linking agent, and the flask was kept at 83 ° C. for 2 hours.

Then, n-heptane and water were heated in an oil bath at 125 ° C. to evaporate and dry to obtain a dried product of polymer particles. The polymer particles are passed through a sieve having an opening of 850 μm, and 0.2% by mass of amorphous silica (Oriental Silicas Corporation, Toxile NP-S) with respect to the mass of the polymer particles is mixed with the polymer particles. , 231.2 g of water-absorbent resin particles c containing amorphous silica were obtained. The medium particle size of the water-absorbent resin particles c was 359 μm.

Production Example 4 Water-absorbent resin particles d
In the first-stage polymerization reaction, the rotation speed of the stirrer adjusted after the addition of the surfactant solution was set to 550 rpm, and in the hydrogel polymer after the second-stage polymerization, 256.8 g by co-boiling distillation. In the same manner as in Production Example 3, except that the water was extracted from the system and the amount of amorphous silica mixed with the polymer particles was changed to 0.5% by mass with respect to the mass of the polymer particles. 230.2 g of water-absorbent resin particles d were obtained. The medium particle size of the water-absorbent resin particles d was 358 μm.

Production Example 5 Water-absorbent resin particles e
A round-bottomed cylindrical separable flask with an inner diameter of 11 cm and a volume of 2 L equipped with a reflux condenser, a dropping funnel, a nitrogen gas introduction pipe, and a stirring blade having four inclined paddle blades with a blade diameter of 5 cm in two stages as a stirrer. Got ready. To this flask, take 293 g of n-heptane as a hydrocarbon dispersion medium, add 0.736 g of a maleic anhydride-modified ethylene-propylene copolymer (Mitsui Chemicals Co., Ltd., High Wax 1105A) as a polymer-based dispersant, and stir. The temperature was raised to 80 ° C. to dissolve the dispersant, and then cooled to 50 ° C.

Then, the first-stage monomer aqueous solution prepared above was added to the separable flask, and after stirring for 10 minutes, 6.62 g of n-heptane was added as a surfactant to the sucrose stearic acid ester of HLB3. Mitsubishi Chemical Foods Co., Ltd., Ryoto Sugar Ester S-370) 0.736 g of a surfactant solution dissolved by heating is further added, and the inside of the system is sufficiently filled with nitrogen while stirring at a stirring speed of 550 rpm. After the replacement, the flask was immersed in a water bath at 70 ° C. to raise the temperature, and the polymerization was carried out for 60 minutes to obtain a first-stage polymerized slurry solution.

After cooling the inside of the separable flask system to 44 ° C. while stirring at a stirring speed of 1000 rpm, the entire amount of the monomer aqueous solution in the second stage is added to the polymerized slurry liquid in the first stage. After adding and replacing the inside of the system with nitrogen for 30 minutes, the flask was again immersed in a water bath at 70 ° C. to raise the temperature, and the polymerization reaction was carried out for 60 minutes to obtain a hydrogel polymer.

After the polymerization, 0.589 g of a 45% by mass diethylenetriamine-5 sodium acetate aqueous solution was added to the obtained hydrogel polymer under stirring. Then, the flask was immersed in an oil bath set at 125 ° C., and 275.8 g of water was extracted from the system while refluxing n-heptane by azeotropic distillation of n-heptane and water. Then, 4.42 g (0.507 mmol) of a 2% by mass ethylene glycol diglycidyl ether aqueous solution was added to the flask as a surface cross-linking agent, and the flask was kept at 83 ° C. for 2 hours.

Then, n-heptane and water were heated in an oil bath at 125 ° C. to evaporate and dry to obtain a dried product of polymer particles. The polymer particles are passed through a sieve having an opening of 850 μm, and 0.2% by mass of amorphous silica (Oriental Silicas Corporation, Toxile NP-S) with respect to the mass of the polymer particles is mixed with the polymer particles. , 233.0 g of water-absorbent resin particles e containing amorphous silica were obtained. The medium particle size of the water-absorbent resin particles e was 128 μm.

Production Example 6 Method for Manufacturing Test Water Absorption Core The following materials were prepared for manufacturing the test water absorption core.
(adhesive)
・ Hot melt adhesive (Henkel Japan Ltd. Softening point 96 ℃ ME-765E)
(Base material of water absorption core for test)
Air-laid non-woven fabric (KNH Enterprise Co., Ltd., 6190516-1A01, basis weight 40 g / m ² )
・ Air-through non-woven fabric (Hualong (Nanjining), basis weight 45 g / m ² )

The air-laid non-woven fabric was cut into two pieces to a size of 10 cm × 30 cm to obtain air-laid non-woven fabric-1 and 2. An air-through non-woven fabric cut to a size of 10 cm x 30 cm is placed on the air-laid non-woven fabric-1, and 1.5 g of water-absorbent resin particles (Sumitomo Seika Chemical Co., Ltd.) are used using an airflow type mixer (Padformer manufactured by Otec Co., Ltd.). Aquakeep SA60S manufactured by Co., Ltd., water absorption of physiological saline 60 g / g, medium particle size 342 μm) were uniformly sprayed.

Air-laid non-woven fabric-2 with hot melt coating machine (Henkel Co., Ltd., pump: Marshal150, table: XA-DT, tank set temperature: 150 ° C, hose set temperature: 165 ° C, gun head set temperature: 170 ° C) Ten 0.2 g of hot melt adhesive (Henkel Japan Ltd., ME-765E) was applied to the base material along the length direction as shown in FIG. 3 at 10 mm intervals. The adhesive application pattern was a spiral stripe. The surface of the air-laid non-woven fabric-2 to which the hot melt was attached was aligned with the surface on which the water-absorbent resin particles of the air-through non-woven fabric were sprayed, sandwiched between release papers, and turned upside down. Then, the release paper and the air-laid non-woven fabric-1 were removed.

Of the air-through non-woven fabric, 4.8 g of water-absorbent resin particles (Aquakeep SA60S manufactured by Sumitomo Seika Co., Ltd., physiological salt) was used on the surface opposite to the surface on which the water-absorbent resin particles were sprayed. A water absorption amount of 60 g / g and a medium particle size of 342 μm) were uniformly sprayed. 0.2 g of hot melt was applied to the removed air-laid nonwoven fabric-1 by the same operation as described above. From the top of the air-through non-woven fabric, align both ends of the air-laid non-woven fabric-1 so that the adhesive coating surface is on the lower side, sandwich it with release paper, and use a laminating machine (Hashima Co., Ltd., Straight Liner Fusion Press, model HP-600LFS, 110 ° C.). , 0.1 MPa) and pasted together to prepare a water-absorbing core for testing. From the top, the test water-absorbing core is in the order of air-laid non-woven fabric-1, hot melt adhesive, absorbent layer made of water-absorbent resin particles, air-through non-woven fabric, absorbent layer made of water-absorbent resin particles, hot-melt adhesive, and air-laid non-woven fabric-2. It is arranged in.

[Preparation of absorbent articles for testing]
Example 1
(Preparation of auxiliary sheet)
Two pieces of tissue having a basis weight of 16 g / m ² were cut into a size of 10 cm × 30 cm to obtain an upper sheet base material and a lower sheet base material of the auxiliary sheet. After uniformly applying 0.3 g of adhesive (3M Spray Glue 77, manufactured by 3M Japan Ltd.) to the inner surface of the roll of the lower sheet base material, a flow-type mixer (pad former, manufactured by Otec Co., Ltd.) was promptly applied. Was used to uniformly spray 1.1 g of the water-absorbent resin particles a1 prepared in Production Example 1. 0.3 g of an adhesive (3M spray glue 77 manufactured by 3M Japan Ltd.) was uniformly applied to the upper sheet base material. The surface coated with the adhesive of the upper sheet base material was overlapped with the surface on which the water-absorbent resin particles of the lower sheet base material were sprayed so that both ends were aligned, and the entire surface was adhered to obtain a water-absorbent sheet for an auxiliary sheet.

(Preparation of absorbent articles for testing)
The obtained water-absorbing sheet for auxiliary sheet was cut into two pieces having a size of 3 cm × 30 cm to obtain an auxiliary sheet. 0.1 g of an adhesive (3M spray glue 77 manufactured by 3M Japan Ltd.) was uniformly applied to one side of the auxiliary sheet. With the adhesive-coated side of the auxiliary sheet facing down, the auxiliary sheet is placed on the surface of the air-laid non-woven fabric-1 of the test water-absorbing core produced in Production Example 6 at both ends in the lateral direction of the main surface of the water-absorbing core. Was glued together along the longitudinal direction of the water absorption core. As a result, a test absorbent article of Example 1 was obtained.

In the auxiliary sheet of Example 1, a tissue, an adhesive, a swelling layer made of water-absorbent resin particles, an adhesive, and a tissue are arranged in this order. The swollen layers in Example 1 are provided on both ends of the water absorbing core in the lateral direction along the longitudinal direction of the water absorbing core. In the test absorbent article of Example 1, the auxiliary sheet is arranged on the user side (the side where the liquid invades) when it is attached. The test absorbent article of Example 1 has the same configuration as shown in FIGS. 4A (top view) and B (side view from one side in the longitudinal direction of the test absorbent article).

Example 2
The test-absorbent article of Example 2 in the same manner as in Example 1 except that the water-absorbent resin particles used for producing the water-absorbent sheet for the auxiliary sheet were changed to the water-absorbent resin particles b produced in Production Example 2. Got

Example 3
The test-absorbent article of Example 3 was obtained in the same manner as in Example 1 except that the amount of the water-absorbent resin particles used for producing the water-absorbent sheet for the auxiliary sheet was changed to 0.6 g.

Example 4
The test absorbent article of Example 4 was obtained in the same manner as in Example 1 except that the size to be cut as an auxiliary sheet was changed to 4 cm × 30 cm.

Example 5
The test absorbent article of Example 5 was obtained in the same manner as in Example 1 except that the size to be cut as an auxiliary sheet was changed to 1 cm × 30 cm.

Example 6
An absorbent article for testing in Example 6 was obtained in the same manner as in Example 1 except that the installation location of the auxiliary sheet was changed to the surface of the air-laid nonwoven fabric-2. The test absorbent article of Example 6 comprises a water absorption core and an auxiliary sheet.

In the auxiliary sheet of Example 6, a tissue, an adhesive, a swelling layer made of water-absorbent resin particles, an adhesive, and a tissue are arranged in this order. The swollen layers in Example 6 are provided on both ends of the water absorbing core in the lateral direction along the longitudinal direction of the water absorbing core. In the test absorbent article of Example 6, the auxiliary sheet is arranged on the side opposite to the user side (the side where the liquid invades) when it is attached. The test absorbent article of Example 6 has the same configuration as shown in FIGS. 7A (top view) and B (side view from one side in the longitudinal direction of the test absorbent article).

Example 7
Two pieces of tissue having a basis weight of 16 g / m ² were cut into a size of 10 cm × 30 cm to obtain an upper sheet base material and a lower sheet base material of the auxiliary sheet. After uniformly applying 0.3 g of adhesive (3M spray glue 77 manufactured by 3M Japan Ltd.) to the inner surface of the roll of the lower sheet base material, a rectangular shape with a short side of 4 cm and a long side of 30 cm in the center of the lower sheet base material. 0.7 g of the water-absorbent resin particles a produced in Production Example 1 was uniformly sprayed on a region other than the region. An adhesive is applied to the upper sheet base material, and the surface to which the adhesive is applied is overlapped with the surface on which the water-absorbent resin particles of the lower sheet base material are sprayed so that both ends are aligned, and the entire surface is adhered to form an auxiliary sheet. Obtained.

0.3 g of an adhesive (3M spray glue 77 manufactured by 3M Japan Ltd.) was uniformly applied to one side of the obtained auxiliary sheet. The adhesive-coated side of the auxiliary sheet was turned downward, and the auxiliary sheet was attached to the entire surface of the air-laid nonwoven fabric-1 of the test water-absorbing core produced in Production Example 6. As a result, a test absorbent article of Example 7 was obtained.

In the test absorbent article of Example 7, the auxiliary sheet is made of tissue as a sheet base material, has a size of 10 cm × 30 cm, and swelling layers are provided in a range of 3 cm × 30 cm at both ends in the lateral direction thereof. ing. Only the tissue and the adhesive as the sheet base material are arranged in the range of 4 cm × 30 cm in the center of the auxiliary sheet in Example 7.

In the auxiliary sheet of Example 7, a tissue, an adhesive, a swelling layer made of water-absorbent resin particles, an adhesive, and a tissue are arranged in this order. The swollen layers in Example 7 are provided on both ends of the water absorbing core in the lateral direction along the longitudinal direction of the water absorbing core. In the test absorbent article of Example 7, the auxiliary sheet is arranged on the side opposite to the user side (the side where the liquid invades) when it is attached. The test absorbent article of Example 7 has the same configuration as shown in FIGS. 5A (top view) and B (side view from one side in the longitudinal direction of the test absorbent article).

Example 8
The same as in Example 1 except that the base material for the auxiliary sheet was changed to a spunlace non-woven fabric (Kuraray Co., Ltd., 70% ration; 20% PET; 10% PP / PE, basis weight 35 g / m ^2). A test absorbent article of Example 8 was obtained.

Example 9
Example 9 in the same manner as in Example 1 except that the base material for the auxiliary sheet was changed to a spunbonded non-woven fabric (Toray Polytech (Nantong) Co., Ltd., LIVESEN hydrophilic SSSS, basis weight 17 g / m ^2). A test absorbent article was obtained.

Example 10
A water absorption sheet for an auxiliary sheet (having a size of 10 cm on the short side and 30 cm on the long side) was prepared by the same method as that described in Example 1. A rectangular region having a short side of 4 cm and a long side of 24 cm, located at the center of the water absorption sheet, was cut. The water-absorbing sheet from which the predetermined region in the central portion was removed was used as an auxiliary sheet for producing an absorbent article of Example 10. The test absorbent article of Example 10 was obtained in the same manner as in Example 1 except that the auxiliary sheet was changed so as to adhere to the entire surface of the air-laid nonwoven fabric-1.

In the auxiliary sheet of Example 10, a tissue, an adhesive, a swelling layer made of water-absorbent resin particles, an adhesive, and a tissue are arranged in this order. The swollen layer in Example 10 is provided along the outer circumference (edge) on the water absorption core. In the test absorbent article of Example 10, the auxiliary sheet is arranged on the user side (the side where the liquid invades) when it is attached. The test absorbent article of Example 10 has the same configuration as shown in FIGS. 6A (top view) and B (side view from one side in the longitudinal direction of the test absorbent article).

Comparative Example 1
Only the water-absorbing core produced in Production Example 6 without using the auxiliary sheet was used as the test-absorbing article of Comparative Example 1. The test-absorbent article of Comparative Example 1 includes only a water-absorbing core, and has the same configuration as that shown in FIGS. 8A (top view) and B (side view from one side in the longitudinal direction of the test-absorbent article). It has a structure.

Comparative Example 2
The test-absorbent article of Comparative Example 2 in the same manner as in Example 1 except that the water-absorbent resin particles used for producing the water-absorbent sheet for the auxiliary sheet were changed to the water-absorbent resin particles c produced in Production Example 3. Got

Comparative Example 3
The test-absorbent article of Comparative Example 3 in the same manner as in Example 1 except that the water-absorbent resin particles used for producing the water-absorbent sheet for the auxiliary sheet were changed to the water-absorbent resin particles d produced in Production Example 4. Got

Comparative Example 4
The test-absorbent article of Comparative Example 4 in the same manner as in Example 1 except that the water-absorbent resin particles used for producing the water-absorbent sheet for the auxiliary sheet were changed to the water-absorbent resin particles e produced in Production Example 5. Got

Comparative Example 5
The water-absorbent resin particles used to prepare the water-absorbent sheet for the auxiliary sheet were changed to the water-absorbent resin particles f collected from the sanitary napkin "Eris Morning Super Safe CLIINS" (purchased in 2017) of Daio Paper Corporation sold in Japan. Except for the above, a test absorbent article of Comparative Example 5 was obtained in the same manner as in Example 1.

Comparative Example 6
Example 1 except that the size to be cut as an auxiliary sheet is set to 3 cm × 10 cm, and the long side of the auxiliary sheet is changed so as to be adhered to the surface of the air-laid non-woven fabric-1 along the short side of the water absorption core. In the same manner as above, a test absorbent article of Comparative Example 6 was obtained.

In the auxiliary sheet in Comparative Example 6, a tissue, an adhesive, a swelling layer made of water-absorbent resin particles, an adhesive, and a tissue are arranged in this order. The swollen layers in Comparative Example 6 are provided at both ends in the longitudinal direction of the water absorption core along the lateral direction of the water absorption core. In the test absorbent article of Comparative Example 6, the auxiliary sheet is arranged on the user side (the side where the liquid invades) when it is attached. The test absorbent article of Comparative Example 6 has a configuration similar to that shown in FIGS. 9A (top view) and B (side view seen from one side in the longitudinal direction).

Hereinafter, unless otherwise specified, the measurement of various performances of the water-absorbent resin particles and the liquid leakage test were carried out in an environment of a temperature of 25 ± 2 ° C. and a humidity of 50 ± 10%.

<Medium particle size>
The above-mentioned medium particle size of the water-absorbent resin particles was measured by the following procedure. That is, from the top of the JIS standard sieve, a sieve with a mesh size of 600 μm, a sieve with a mesh size of 500 μm, a sieve with a mesh size of 425 μm, a sieve with a mesh size of 300 μm, a sieve with a mesh size of 250 μm, a sieve with a mesh size of 180 μm, and a sieve with a mesh size of 150 μm. , And the saucer in that order. 50 g of water-absorbent resin particles were placed in the best combined sieve, and the mixture was classified according to JIS Z 8815 (1994) using a low-tap shaker (manufactured by Iida Seisakusho Co., Ltd.). After classification, 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 relationship between the mesh size of the sieve and the integrated value of the mass percentage of the particles remaining on the sieve was plotted on a logarithmic probability paper by integrating on the sieve in order from the one having the largest particle size with respect to this particle size distribution. 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.

<Water absorption (saline)>
500 g of physiological saline was weighed in a beaker having a capacity of 500 mL. There, 2.0 g of water-absorbent resin particles were dispersed so as not to generate mamaco while stirring at 600 rpm using a stirrer bar (8 mmφ × 30 mm, without ring). It was left in that state for 60 minutes to sufficiently swell the water-absorbent resin particles. Subsequently, the contents in the beaker were filtered using a standard sieve having a mesh size of 75 μm (mass Ma (g)). Excess water was filtered off from the swollen gel on the sieve by allowing the sieve to be tilted at an inclination angle of about 30 degrees with respect to the horizontal for 30 minutes. Then, the total mass Mb (g) of the sieve and the swollen gel on the sieve was measured. The amount of water absorption of physiological saline was determined by the following formula.
Water absorption of saline [g / g] = (Mb-Ma) /2.0

[Water absorption rate (Vortex method)]
The water absorption rate of the water-absorbent resin particles with respect to physiological saline was measured by the following procedure based on the Vortex method. First, 50 ± 0.1 g of physiological saline adjusted to a temperature of 25 ± 0.2 ° C. in a constant temperature water tank was weighed in a beaker having a capacity of 100 mL. Next, a vortex was generated by stirring at 600 rpm using a magnetic stirrer bar (8 mmφ × 30 mm, without ring). 2.0 ± 0.002 g of water-absorbent resin particles were added to physiological saline at one time. The time [seconds] from the addition of the water-absorbent resin particles to the time when the vortex on the liquid surface converged was measured, and the time was recorded as the water absorption rate of the water-absorbent resin particles.

<Measurement of swelling power of water-absorbent resin particles>
The swelling power test of the water-absorbent resin particles was performed using the apparatus shown in FIG. The swelling power test was carried out according to the procedure shown below. A small tabletop tester EZ-Test manufactured by Shimadzu Corporation was used to measure the swelling power of the water-absorbent resin particles.

^{(1) Made of acrylic resin having an inner diameter of 20 mm (bottom area 3.14 cm 2} ) and a height of 50 mm, which has openings at both ends and nylon (registered trademark) mesh 71 (255 mesh) is attached to one of the openings. A cylinder 72 was prepared.
(2) On the nylon (registered trademark) mesh 71 of the cylinder 72, with the cylinder 72 standing vertically with the opening on the side where the nylon (registered trademark) mesh 71 is mounted facing down. 0.1 g of water-absorbent resin particles 73 were uniformly sprayed. It was visually confirmed that it was uniform. If necessary, the cylinder 72 was shaken to make the water-absorbent resin particles 73 uniform. A cylindrical jig 74 (cylindrical weight) made of acrylic resin having a diameter of 19.5 mm and a height of 59 mm and a mass of 20.5 g is inserted into the cylinder 72, and the cylindrical jig 74 is placed on the water-absorbent resin particles 73. Was placed.
(3) A petri dish 75 having a diameter of 100 mm was horizontally placed on the measurement table of EZ-Test. A dry glass filter 76 (filter hole diameter G1) having a diameter of 50 mm and a thickness of 5 mm was placed in the central portion of the petri dish 75, and physiological saline 77 was injected to a position slightly below the upper surface of the glass filter 76 ( About 20 ml).
(4) A 50 mm × 50 mm impermeable liquid sheet 78 is placed near the center of the upper surface of the glass filter 76 in which the physiological saline 77 has permeated, and the impermeable resin sheet 78 contains the water-absorbent resin particles 73. The cylinder 72 was placed vertically with the nylon (registered trademark) mesh 71 facing down.
(5) The load cell 79 was arranged so that the pressure-sensitive portion having a diameter of 20 mm connected to the load cell 79 of the EZ-Test was located immediately above the cylindrical jig 74 in the cylinder 72. More specifically, by moving the load cell measurement table up and down, the pressure-sensitive part connected to the load cell 79 is brought close to the acrylic resin cylindrical jig 74, and stops when a slight pressure due to contact is observed. did. Next, the load cell measurement table was moved upward little by little, and the position where the pressure indicated value became 0 ± 0.05 (unit: Newton: N) was set as the measurement start point.
(6) The impermeable sheet 78 was promptly removed to start water absorption by the water-absorbent resin particles 73.
(7) The time when the impermeable sheet 78 is removed is set to the elapsed time t = 0 [seconds], and the change over time of the force generated by the swelling of the water-absorbent resin particles 73 that have absorbed the physiological saline 77 is measured by the load cell 79 for 60 seconds. The measurement was performed, and the value of t = 10 [seconds] was defined as the 10-second value of the swelling force, and the value of t = 10 [seconds] was defined as the 60-second value of the swelling force.

Table 1 shows the measurement results of water absorption, water absorption rate, and swelling power for 10 seconds and 60 seconds.

<Liquid leak test>
(Preparation of artificial urine)
Artificial urine was prepared with the formulation shown below.
-Ion-exchanged water: 9865.75 g
-NaCl: 100.0 g
・ CaCl ₂・ H ₂ O: 3.0 g
_{_{· MgCl 2 · 6H 2 O:}} 6.0g
-Triton X-100 (1%): 25.0 g
-Edible blue No. 1 (for coloring): 0.25 g

(Crotch leak test)
A crotch leak test was performed using the device shown in FIG. The device shown in FIG. 11 is a device that imitates a standing position and a sitting position. A test absorbent article is placed on the device, and artificial urine is injected from vertically above the center of the test absorbent article with a dropping funnel. Thereby, the amount of artificial urine leaked from the short side of the test absorbent article is evaluated.

(1) The aluminum formwork 54 was assembled by assembling

aluminum parts

54a and 54b (the width of the aluminum frame is 3 cm) so that the horizontal distance between the insides of the aluminum parts was 15 cm.
(2) Of the impermeable sheet 53 cut out to a size of 10 cm x 40 cm (used by processing Unipack L size, a plastic bag with a polyethylene zipper manufactured by Seinichi Co., Ltd.), one end in the lateral direction is made of aluminum part 54a. The other end was attached to the end of the component 54b on the component 54b side, and the other end was attached to the end of the component 54b on the component 54a side. At this time, the most slack portion of the impermeable sheet 53 was set at a position 9 cm vertically above the surface (horizontal plane) on which the measuring device was installed.

(4) A mark was placed at the center of the prepared test absorbent article 200.
(5) The test absorbent article 200 was placed on the impermeable sheet 53 imitating the back sheet of the measuring device, and the center of the test absorbent article 200 was placed on the most slack portion of the impermeable sheet 53. At this time, the test absorbent article 200 was placed in a state where the absorbent article 200 was exposed, and no top sheet or the like was used.
(6) Dropping funnel 52 (dropping funnel 52) whose dropping speed was adjusted to 8 ml / sec, with the position 1 cm above the center of the test absorbent article 200 in the vertical direction (10 cm above the surface on which the device was installed) as the loading point. Using a 300 ml dropping funnel manufactured by Cosmos Bead Co., Ltd. and an inner diameter of the tip of 8 mm × 6 mm), 40 ml of artificial urine 51 adjusted to a liquid temperature of 25 ° C. was injected.
(7) The artificial urine 51 leaked from the test absorbent article 200 was collected in a SUS tray 55 arranged on the balance 56, which was previously installed in the downward direction of the test absorbent article 200. The collected artificial urine 51 was weighed using a balance 56.

Table 2 shows the composition of the auxiliary sheet and the evaluation results. In Table 2, the "user side" means that the auxiliary sheet is placed on the user side (the side where the liquid invades) when the user wears the auxiliary sheet on the main surface of the water absorption core, and the "outside" means that the auxiliary sheet is placed. It means that it is placed on the side opposite to the user side when it is worn by the user on the main surface of the water absorption core.

The "longitudinal ends" in Table 2 mean that the swelling layer is provided on both ends of the water absorption core in the lateral direction along the longitudinal direction of the water absorption core.

By providing a swelling layer containing the water-absorbent resin particles at a predetermined position on the auxiliary sheet and controlling the 10-second value of the swelling force of the water-absorbent resin particles contained in the swelling layer to a specific value, the user is in a wearing state. It was shown that liquid leakage (crotch leakage) was suppressed.

(Abdominal leak, back leak test)
A crotch leak and back leak test were performed using the device shown in FIG. The device shown in FIG. 12 is a device that imitates lying on the back and lying down, and by placing the test absorbent article 200 on the device and injecting artificial urine toward the center of the test absorbent article 200 with a liquid feed pump. , The amount of artificial urine leaked is evaluated.

(1) Place the test absorbent article 200 on the U-shaped acrylic resin instrument 81 so that the center of the test absorbent article 200 is the center of the instrument, and tape any part so that it does not shift. Fixed with.
(2) The acrylic resin instrument 81 was installed on the measuring table 84 in a state of being opened in the horizontal direction, and was separated from the center of the test absorbent article 200 and the test absorbent article 200 in the horizontal direction by 1 cm. A point was set as a charging point, and a drainage port (diameter 0.4 cm) of a liquid feeding pump 82 (INTERGRA Bioscience AG, model: DOSEI IT P910) for liquid charging was arranged.
(3) 80 ml of artificial urine adjusted to a liquid temperature of 25 ° C. was injected at a rate of 8 ml / sec. The artificial urine leaked from the test absorbent article 200 is previously installed in the downward direction of the test absorbent article 200, and is collected and measured by a SUS tray 82 placed on the balance 83.

Table 3 shows the composition of the auxiliary sheet and the evaluation results. “User side” and “longitudinal end” in Table 3 have the same meaning as in Table 2. In "longitudinal and short ends" in Table 3, swelling layers are provided on both ends of the water absorption core in the longitudinal direction along the short direction of the water absorption core, and on both ends in the short direction. In the "short end", the swelling layer is provided on both ends of the water absorption core in the longitudinal direction along the longitudinal direction of the water absorption core. Means that.

By providing a swelling layer containing the water-absorbent resin particles at a predetermined position on the auxiliary sheet and controlling the 10-second value of the swelling force of the water-absorbent resin particles contained in the swelling layer to a specific value, the user is in a wearing state. It was shown that liquid leakage (abdominal leakage and back leakage) was suppressed.

10 ... Absorbent layer, 10a ... Water-absorbent resin particles, 10b ... Fiber layer, 20a, 20b ... Core wrap sheet, 21 ... Adhesive, 30 ... Liquid permeable sheet, 40 ... Liquid impermeable sheet, 50 ... Water-absorbing core, 60 ... Auxiliary sheet, 61 ... Swelling layer, 61a ... Water-absorbent resin particles, 61b ... Fiber layer, 62a, 62b ... Sheet base material, 63a, 63b ... Adhesive, 100 ... Absorbent article.

Claims

It is provided with a strip-shaped water absorption core, an auxiliary sheet for assisting liquid absorption by the water absorption core, a liquid impermeable sheet, and a liquid permeable sheet.
The liquid permeable sheet, the water absorption core, and the liquid permeable sheet are arranged in this order.
The auxiliary sheet is arranged between the impermeable sheet and the water absorbing core and / or between the water absorbing core and the liquid permeable sheet.
The auxiliary sheet has a swelling layer containing water-absorbent resin particles and has a swelling layer.
The swelling layer is provided on both ends of the water absorption core in the lateral direction along the longitudinal direction of the water absorption core.
The 10-second value of the swelling force of the water-absorbent resin particles contained in the swelling layer measured in the swelling force test performed in the order of i), ii), iii), iv) and v) below is 5 N or more. Is an absorbent article.
i) A cylinder having openings at both ends and having a mesh mounted on one of the openings and having an inner diameter of 20 mm is prepared, and the cylinder is vertically erected with the side on which the mesh is mounted facing downward. Then, 0.1 g of water-absorbent resin particles are uniformly sprayed on the mesh in the cylinder, and a cylindrical jig having a diameter of 19.5 mm is placed on the mesh.
ii) A glass filter having a thickness of 5 mm is placed in a horizontally installed petri dish, and the glass filter is impregnated with physiological saline to a position slightly below the upper surface thereof.
iii) An impermeable sheet is placed on the upper surface of the glass filter in which the physiological saline has permeated, and the cylinder containing the water-absorbent resin particles is placed on the impermeable sheet so that the mesh faces downward. Stand vertically.
iv) The impermeable sheet is removed to start water absorption by the water-absorbent resin particles.
v) The force for pushing up the cylindrical jig generated by the swelling of the water-absorbent resin particles 10 seconds after the impermeable sheet is removed is measured by a load cell and recorded as a 10-second value of the swelling force. To do.
The absorbent article according to claim 1, wherein the swollen layer is further provided on both ends of the water absorbing core in the longitudinal direction along the lateral direction of the water absorbing core.
The absorbent article according to claim 1 or 2, which is a diaper.
An auxiliary sheet used to assist the absorption of liquid in the water absorption core in an absorbent article provided with a strip-shaped water absorption core.
With a swollen layer containing water-absorbent resin particles,
When the 10-second value of the swelling force of the water-absorbent resin particles contained in the swelling layer is 5 N or more, which is measured in the swelling force test performed in the order of i), ii), iii), iv) and v) below. There is an auxiliary sheet.
i) A cylinder having openings at both ends and having a mesh mounted on one of the openings and having an inner diameter of 20 mm is prepared, and the cylinder is vertically erected with the side on which the mesh is mounted facing downward. Then, 0.1 g of water-absorbent resin particles are uniformly sprayed on the mesh in the cylinder, and a cylindrical jig having a diameter of 19.5 mm is placed on the mesh.
ii) A glass filter having a thickness of 5 mm is placed in a horizontally installed petri dish, and the glass filter is impregnated with physiological saline to a position slightly below the upper surface thereof.
iii) An impermeable sheet is placed on the upper surface of the glass filter in which the physiological saline has permeated, and the cylinder containing the water-absorbent resin particles is placed on the impermeable sheet so that the mesh faces downward. Stand vertically.
iv) The impermeable sheet is removed to start water absorption by the water-absorbent resin particles.
v) The force for pushing up the cylindrical jig generated by the swelling of the water-absorbent resin particles 10 seconds after the impermeable sheet is removed is measured by a load cell and recorded as a 10-second value of the swelling force. To do.