JP6656100B2 - Absorbent for absorbent article and absorbent article including the absorbent - Google Patents

Description

  The present disclosure relates to an absorbent body for an absorbent article such as a disposable diaper and an absorbent article including the absorbent body.

  In recent years, research has been continued on absorbent articles such as disposable diapers in order to realize high absorption performance for excreted liquid such as urine discharged from a wearer. When the content of superabsorbent polymer (SAP) particles in the absorbent core constituting the absorbent body is increased to increase the liquid absorption capacity for the purpose of reducing the thickness of the absorbent article, the SAP particles absorb the body fluid. When the swelling and gelation occur, a so-called gel blocking phenomenon occurs, and the liquid permeability and the liquid diffusivity are significantly reduced. In view of such a defect, Patent Document 1 proposes a water-absorbing sheet in which a primary absorbent layer and a secondary absorbent layer divided by a water-permeable substrate having a water permeability index of 20 to 90 are sandwiched by a hydrophilic nonwoven fabric. Patent Literature 2 proposes a water-absorbing sheet (absorber) in which a primary absorbent layer and a secondary absorbent layer divided by a fiber matrix having a porosity of 91 to 99% are sandwiched between nonwoven fabrics.

International Publication No. 2010/076857 International Publication No. 2011/136087

  In the absorbers proposed in Patent Literatures 1 and 2, the primary and secondary absorbent layers are made of a mixed powder of SAP particles and a hot melt adhesive, and an intermediate sheet (a water-permeable or fiber matrix) that divides these absorbent layers. At least one selected from the group consisting of sanitary paper, cellulose-containing synthetic fiber nonwoven fabric, rayon-containing synthetic fiber nonwoven fabric, and synthetic fiber nonwoven fabric subjected to hydrophilic treatment is used. However, the surface of the intermediate sheet has high smoothness, and it is difficult for SAP particles to be retained on the surface of the intermediate sheet. In addition, when the content of SAP with respect to the hot melt adhesive is increased in order to enhance the liquid absorbing ability, SAP particles are less likely to be retained on the surface of the intermediate sheet. As a result, after the SAP particles swell before and after absorbing the liquid, the SAP particles move in the absorber due to the action of the wearer and the SAP particles are unevenly distributed, and the shape of the absorber cannot be maintained. The absorption capacity of the absorber decreases. When the absorption capacity of the absorber decreases, there is a problem that leakage of the body fluid tends to occur when the body fluid, particularly urine, is excreted several times. In addition, when the intermediate sheet is used as it is in the manufacture of the absorbent body as proposed in Patent Documents 1 and 2, the wearer wears an absorbent article such as a disposable diaper provided with the absorbent body including the intermediate sheet. When the absorber is worn, it is difficult for the absorber to follow the movement of the wearer, and when the absorber is bent, a corner is likely to be formed.

  For this reason, the present disclosure is directed to an absorbent material that is less likely to cause uneven distribution of SAP particles even when it repeatedly absorbs a bodily fluid such as urine, can maintain a high level of absorptivity, and further improves a feeling of wearing by a wearer. And an absorbent article including the absorber.

  The present inventors have conducted intensive studies on the above problems, and as a result, the absorbent core was disposed between the primary and secondary absorbent layers containing the superabsorbent polymer particles, and between the primary and secondary absorbent layers. In an absorber having an intermediate sheet, the intermediate sheet has an upper surface in contact with the primary absorbent layer and a lower surface in contact with the secondary absorbent layer, the intermediate sheet has a concave portion and a convex portion on at least the upper surface, and has an average convexity. The part interval is 1 to 10 times the average particle size of the superabsorbent polymer particles, and the intermediate sheet has a tensile strength of 0.5 to 7 N / 25 mm in a dry state and a tensile strength of less than 1 N / 25 mm in a wet state. It has been found that the above object can be achieved when the material has strength, and the present disclosure has been completed.

  That is, the present disclosure includes an absorbent core having a longitudinal direction and a transversal direction, and a core wrap sheet, wherein the absorbent core includes primary and secondary absorbent layers containing superabsorbent polymer particles, and the primary absorbent layer. And an intermediate sheet disposed between the secondary absorbent layer and the secondary absorbent layer, wherein the intermediate sheet has an upper surface in contact with the primary absorbent layer and a lower surface in contact with the secondary absorbent layer. The intermediate sheet has a concave portion and a convex portion at least on the upper surface, the average convex portion interval is 1 to 10 times the average particle size of the superabsorbent polymer particles, and the intermediate sheet is 0.5% in a dry state. An absorbent body having a tensile strength of ７7 N / 25 mm and having a tensile strength of less than 1 N / 25 mm in a wet state. The present disclosure further provides an absorbent article including the above absorbent body.

  According to the present disclosure, even when body fluids such as urine are repeatedly absorbed, uneven distribution of SAP particles is unlikely to occur, the absorption ability can be maintained at a high level, and further, an absorber that improves the feeling of wearing of the wearer And an absorbent article including the absorber.

FIG. 1 is a development view of an example of an absorbent article that can include the absorber of the present disclosure. FIG. 2A is a cross-sectional view schematically illustrating one embodiment of the absorber of the present disclosure, and FIG. 2B is a cross-sectional view of another embodiment of the absorber of the present disclosure. FIG. 3 is a plan view schematically showing one embodiment of the intermediate sheet. FIG. 4A is a partial cross-sectional perspective view of the intermediate sheet shown in FIG. 3 along the line IV-IV, and FIG. 4B is a partial cross-sectional perspective view schematically showing another embodiment of the intermediate sheet. is there. FIG. 5 is a diagram schematically illustrating an example of a manufacturing apparatus for manufacturing an intermediate sheet. FIG. 6 is a main part enlarged perspective view schematically showing a pair of shaping rolls of a shaping apparatus that can be used for manufacturing an intermediate sheet. FIG. 7 is an enlarged view of a main part schematically showing an arrangement of pins of a lower shaping roll. FIG. 8 is an enlarged view of a main part showing a state where the upper shaping roll and the lower shaping roll are engaged with each other. FIG. 9 is a diagram schematically showing an apparatus for measuring the water permeability index of a sheet.

The absorber of the present disclosure will be described in detail below.
The present disclosure includes the following aspects.
[Aspect 1]
An absorbent core having a longitudinal direction and a transversal direction, and a core wrap sheet, wherein the absorbent core comprises a primary and secondary absorbent layer containing superabsorbent polymer particles, and the primary and secondary absorbent layers. An absorbent body for an absorbent article having an intermediate sheet disposed therebetween, wherein the intermediate sheet has an upper surface in contact with the primary absorbent layer and a lower surface in contact with the secondary absorbent layer. It has a concave portion and a convex portion on at least the upper surface, the average convex portion interval is 1 to 10 times the average particle size of the superabsorbent polymer particles, and the intermediate sheet has a tensile strength of 0.5 to 7 N / 25 mm in a dry state. Having a tensile strength of less than 1 N / 25 mm in a wet state.
In the absorber according to the above aspect 1, the contact area between the intermediate sheet and the superabsorbent polymer particles in the primary absorbent layer is reduced because the intermediate sheet has concave portions and convex portions characterized by the predetermined average convex portion interval. By increasing, it is possible to improve the retention of the superabsorbent polymer particles, before and after absorption of the liquid, it is possible to suppress that the superabsorbent polymer particles move and unevenly distributed, as a result, Gel blocking can be suppressed, and the shape of the absorber can be suppressed, and the liquid absorbency and shape retention of the absorber can be improved. Furthermore, because the intermediate sheet has a weak tensile strength when wet, the unevenness of the intermediate sheet is deformed or partially torn in conformity to the swelling of the superabsorbent polymer particles, and the superabsorbent polymer particles bite into the intermediate sheet. Since the anchor effect is generated, the shape of the absorber can be further suppressed, and the shape retention of the absorber can be further improved. Furthermore, the absorbent body according to the first aspect can improve the wearing feeling of the wearer because the intermediate sheet is flexible.

[Aspect 2]
The absorbent body according to the above aspect 1, wherein the intermediate sheet is a sheet containing 50% by mass or more of pulp fibers.
The absorber according to the above aspect 2 can provide good liquid absorbency and flexibility.

[Aspect 3]
The absorber according to the above aspect 1 or 2, wherein the intermediate sheet has, on the lower surface, concave portions and convex portions having an average interval between convex portions of 1 to 10 times the average particle size of the superabsorbent polymer particles.
The absorber according to the above aspect 3 has unevenness also on the lower surface of the intermediate sheet, so that the contact area between the intermediate sheet and the superabsorbent polymer particles in the secondary absorbent layer is increased, so that the superabsorbent polymer particles are increased. Can be suppressed, and the superabsorbent polymer particles can be prevented from moving and unevenly distributed, and as a result, the liquid absorbency and shape retention of the absorber can be further improved.

[Aspect 4]
The absorbent body according to any one of Aspects 1 to 3, wherein the intermediate sheet has a plurality of apertures.
The absorbent body according to the fourth aspect is characterized in that the superabsorbent polymer particles swollen while the apertures are widened in accordance with the swelling of the superabsorbent polymer particles and bite into the intermediate sheet at the apertures. Retention can be improved.

[Aspect 5]
The absorbent body according to any one of aspects 1 to 4, wherein 90 to 100% by mass of the superabsorbent polymer is composed of superabsorbent polymer particles having a particle size of 150 µm or more and less than 500 µm.
In the absorber according to the fifth aspect, since the superabsorbent polymer particles are small and uniform, they are easily held by the unevenness or the opening of the intermediate sheet, so that the retention of the superabsorbent polymer particles can be further improved. .

[Aspect 6]
The absorbent body according to any one of Aspects 1 to 5, wherein the density of the intermediate sheet is lower than the density of the core wrap sheet.
In the absorbent body according to the sixth aspect, by lowering the density of the intermediate sheet than that of the core wrap sheet, it is possible to improve the liquid suction property to the inside of the absorbent body. Since the density of the core wrap sheet is high, the bodily fluid migrates to the primary absorbent layer while diffusing in the core wrap sheet, and the intermediate sheet has a low density, so that the bodily fluid can be quickly transmitted to the secondary absorbent layer. Since the transfer is performed, the absorber can be used efficiently and in a well-balanced manner, and the ability to suck liquid into the absorber can be improved.

[Aspect 7]
The absorber according to any one of Aspects 1 to 6, wherein at least one of the primary and secondary absorbent layers and at least one of the intermediate sheet and the core wrap sheet are intermittently adhered with an adhesive. .
In the absorbent body according to the seventh aspect, since at least one of the primary and secondary absorbent layers is intermittently adhered to at least one of the intermediate sheet and the core wrap sheet, the superabsorbent polymer particles hardly move and absorb. Body shape retention can be improved. In addition, since the adhesive is intermittently bonded, it does not hinder the permeation of bodily fluids and the deformation or tearing of the intermediate sheet.

[Aspect 8]
The absorbent body according to any one of aspects 1 to 7, wherein the intermediate sheet has a water permeability index of more than 90.
The absorbent body according to the above aspect 8, by rapidly penetrating the body fluid into the secondary absorption layer (lower side), reduces gel blocking in the primary absorption layer (upper side) even when the body fluid is repeatedly absorbed, Good drainage can be provided.

[Aspect 9]
The concave portions and the convex portions on the upper surface of the intermediate sheet are a plurality of grooves that are recessed from the upper surface of the intermediate sheet toward the lower surface, and a plurality of ridges that protrude from the lower surface of the sheet toward the upper surface. The plurality of grooves and the plurality of ridges extend in a first direction parallel to the longitudinal direction of the absorbent core, and are provided alternately at predetermined intervals in a second direction orthogonal to the first direction. The absorbent body according to any one of the above aspects 1 to 8, wherein
In the absorber according to the ninth aspect, the ridges and the grooves extend in parallel with the longitudinal direction (first direction) of the intermediate sheet, so that the diffusion of the bodily fluid in the first direction can be promoted, and the absorption speed can be increased. it can. Further, the presence of the grooves and ridges in the intermediate sheet can increase the flexibility of the intermediate sheet.

[Aspect 10]
Each groove on the upper surface of the intermediate sheet has a groove bottom, and a plurality of second grooves provided discontinuously in the groove bottom in the first direction and depressed from the upper surface to the lower surface. 10. The absorbent body according to the above aspect 9, wherein the absorbent body comprises:
In the absorber according to the tenth aspect, when the intermediate sheet is viewed from the upper surface side, the intermediate sheet is depressed in two stages, so that the flexibility of the intermediate sheet can be further increased.

[Aspect 11]
The absorbent body according to the above aspect 10, wherein the intermediate sheet has an opening in a second concave portion.
In the absorbent body according to the eleventh aspect, the high water-absorbing polymer particles which are swollen while the apertures provided in the second concave portion are widened in accordance with the swelling of the high water-absorbing polymer particles are provided in the second concave portion. Since it penetrates into the intermediate sheet at the opening, the retention of the superabsorbent polymer particles can be improved.

[Aspect 11]
An absorbent article comprising the absorber according to any one of the above aspects 1 to 11.
Since the absorbent article according to the twelfth aspect includes the absorbent body according to any one of the first to eleventh aspects, the absorbent article exerts an effect exerted by the absorbent body.

Hereinafter, the present disclosure will be described with reference to the drawings.
FIG. 1 is a developed view (front view) of an embodiment of the absorbent article according to the present disclosure, and more specifically, is a developed view of a disposable diaper 1. The disposable diaper 1 shown in FIG. 1 includes a liquid-permeable sheet 2, a liquid-impermeable sheet (not shown), and an absorber 3 between the liquid-permeable sheet 2 and the liquid-impermeable sheet. The disposable diaper 1 shown in FIG. 1 also has a pair of three-dimensional gathers 4 and a pair of tape fasteners 5. In the disposable diaper 1 shown in FIG. 1, the lower side of the paper is the front side of the wearer, and the upper side of the paper is the back side of the wearer. The longitudinal direction (longitudinal direction) D1 and the transverse direction (lateral direction) D2 of the absorber 3 correspond to the longitudinal direction D1 and the transverse direction D2 of the disposable diaper 1, respectively.

  FIG. 2A is a cross-sectional view schematically illustrating an internal structure of an embodiment of the absorber of the present disclosure. The absorber 3 includes an absorbent core 6 and a core wrap sheet 7 that covers the absorbent core 6. Prepare. The absorption core 6 includes a primary absorption layer 6a and a secondary absorption layer 6b containing SAP particles, and an intermediate sheet 6c disposed between the primary and secondary absorption layers. FIG. 2B is a cross-sectional view schematically illustrating the internal structure of another embodiment of the absorber of the present disclosure. As in the embodiment illustrated in FIG. A core 6 and a core wrap sheet that covers the absorbent core 6 are provided. The absorption core 6 includes a primary absorption layer 6a and a secondary absorption layer 6b containing SAP particles, and an intermediate sheet 6c disposed between the primary and secondary absorption layers. In the embodiment shown in FIG. 2B, the intermediate sheet 6c and the primary absorption layer 6a and the secondary absorption layer 6b are intermittently adhered via the adhesive 8, and further, the absorbent core 6 and the core The lap sheet 7 is intermittently adhered to the wrap sheet 7 with an adhesive 8.

  In the absorber of the present disclosure, the intermediate sheet has an upper surface and a lower surface, and the intermediate sheet contacts the primary absorption layer on the upper surface side and contacts the secondary absorption layer on the lower surface side. The intermediate sheet has at least a concave portion and a convex portion on the upper surface, and the average convex portion interval is 1 to 10 times the average particle size of the SAP particles. Here, “the upper surface in contact with the primary absorbent layer” means the surface of the intermediate sheet on the side where the liquid to be absorbed by the absorber of the present disclosure flows into the absorbent core, depending on the absorbent article. “Average convex part interval” means the distance between the tops of adjacent convex parts measured using a two-dimensional laser displacement meter. Examples of the two-dimensional laser displacement meter include a high-precision two-dimensional laser displacement meter LJ-G series (model: LJ-G030) manufactured by Keyence Corporation. Since the surface of the intermediate sheet on the side into which the liquid flows has a concave portion and a convex portion, in the primary absorption layer exposed to a larger amount of liquid than the secondary absorption layer, the SAP particles swollen by absorbing the liquid are removed. Uneven distribution due to the action of the wearer can be suppressed. Further, even before the liquid absorption, since the SAP particles are easily held in the concave portions and the convex portions having the above-mentioned predetermined average convex portion interval, uneven distribution of the SAP particles before and after swelling (liquid absorption) can be suppressed. If the average interval between the convex portions is less than one time the average particle size of the SAP particles, the SAP particles are unlikely to fit between adjacent convex portions (that is, concave portions), and the average interval between the convex portions exceeds 10 times the average particle size of the SAP particles. Therefore, it is considered that it is hard to be caught between the adjacent convex portions. The intermediate sheet preferably also has, on the lower surface, concave portions and convex portions having an average interval between convex portions of 1 to 10 times the average particle size of the SAP. By having such concave portions and convex portions also on the lower surface of the intermediate sheet, uneven distribution of SAP particles in the secondary absorption layer can be suppressed. As a result, the shape retention of both the primary and secondary absorbent layers can be improved, and the improvement of the shape retention of the absorber can be further enhanced.

  In the absorbent body of the present disclosure, the intermediate sheet has a tensile strength of 0.5 to 7 N / 25 mm in a dry state and has a tensile strength of less than 1 N / 25 mm in a wet state. In order to stably produce the absorber of the present disclosure in-line, the tensile strength in a dry state is preferably 0.5 N / 25 mm or more. However, as long as the effects of the present disclosure are not impaired, the line suitability can be improved by providing the intermediate sheet with a portion that is not subjected to unevenness processing. When the absorber absorbs the liquid, the irregularities of the intermediate sheet are deformed or partially torn in accordance with the swelling of the SAP particles, and the SAP particles bite into the intermediate sheet, so that the tensile strength in a dry state is 7 N / 25 mm. The following is preferred. Here, the tensile strength in the dry state and the wet state is the tensile strength in the machine (MD) direction, and as described later, the tensile strength in the dry state is 24 ° C. under the conditions of 20 ° C. and 65% relative humidity. It means the tensile force at break (N / 25 mm) when a sample left to dry for a period of time is measured with a Tensilon type tensile tester at a chuck interval of 100 mm and a tensile speed of 100 mm / min. As described later, the tensile strength in a wet state was determined by spraying distilled water equivalent to 250% of the sample mass corresponding to a chuck interval of 100 mm in a mist and leaving the sample to stand for 1 minute in an atmosphere of 20 ° C. and 65% relative humidity. Means the tensile force at break (N / 25 mm) when measured with a Tensilon type tensile tester at a chuck interval of 100 mm and a tensile speed of 100 mm / min.

  In the absorbent body of the present disclosure, the intermediate sheet preferably contains at least 50% by mass of pulp fibers. Under the conditions of the tensile strength in the dry state and the wet state, by including the pulp fiber of 50% by mass or more, when the absorber absorbs the liquid, the unevenness of the intermediate sheet is deformed in accordance with the swelling of the SAP particles. When the SAP particles are broken or partially broken and the SAP particles bite into the intermediate sheet, an anchor effect is easily generated, and the shape of the absorber can be further suppressed. The intermediate sheet preferably has a plurality of apertures. Since the swelled SAP particles bite into the intermediate sheet at the opening portion while the opening portion expands in accordance with the swelling of the SAP particles, the SAP particle retention can be improved.

  In the absorbent body of the present disclosure, the density of the intermediate sheet is preferably smaller than the density of the core wrap sheet. In the case where the density of the intermediate sheet is lower than that of the core wrap sheet, it is possible to improve the liquid suction property to the inside of the absorber. Since the density of the core wrap sheet is high, the bodily fluid migrates to the primary absorbent layer while diffusing in the core wrap sheet, and the intermediate sheet has a low density, so that the bodily fluid can be quickly transmitted to the secondary absorbent layer. Since the transfer is performed, the absorber can be used efficiently and in a well-balanced manner, and the ability to suck liquid into the absorber can be improved. By rapidly penetrating the bodily fluid into the secondary absorbent layer (lower side), even if the bodily fluid is repeatedly absorbed, gel blocking in the primary absorbent layer (upper side) is reduced and good drainage is maintained. Therefore, the intermediate sheet preferably has a water permeability index of more than 90.

In the absorbent body of the present disclosure, the intermediate sheet preferably has an absorption height of 30 mm or more in a water absorption test by the Krem method. This is from the viewpoint of ensuring the diffusivity in the plane direction in the core wrap. In addition, in the water absorption test by the Krem method, the upper limit of the measurement of the absorption height is 200 mm, and in the absorber of the present disclosure, in the water absorption test by the Krem method, the upper limit of the absorption height of the core wrap is 200 mm. is there. In the present disclosure, the water absorption test according to the Krem method is measured in accordance with the water absorption test method according to the Krem method of JIS P 8141: 2004, and the specific procedure is as follows.
(1) A sample is cut into a size of 230 mm × 25 mm (length × width), and its initial mass: W ₀ (g) is measured.
(2) An artificial urine is filled up to a height of 35 mm into a rectangular parallelepiped immersion container of 170 mm × 90 mm × 40 mm (length × width × depth). In addition, artificial urine is prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and about 1 g of a pigment: Blue No. 1 in 10 L of ion-exchanged water.
(3) The sample is fixed to a hanging device, the lower end in the length direction: 30 mm is immersed in artificial urine, and left for 5 minutes.
(4) After standing in a room at 20 degrees and 65 RH% for one day, the height at which the artificial urine rises is measured as the absorption height.
(5) Next, the sample is detached from the hanging tool, and a portion 30 mm long immersed in artificial urine is cut off, and the mass of the sample: W ₁ (g) is measured.
(6) Calculate absorption capacity: X according to the following equation.
X = [(W ₁ × 230/200) −W ₀ ] / W ₀
(7) The above experiment is repeated five times, and the average value is adopted.

  In the absorber of the present disclosure, the SAP particles included in the primary and secondary absorption layers can be SAP particles known in the art. Examples of SAPs include, for example, starch-based, cellulose-based, and synthetic polymer-based polymer absorbents. Examples of starch-based or cellulose-based SAPs include starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, and crosslinked sodium carboxymethyl cellulose. Examples of synthetic polymer SAPs include polyacrylates, polysulfonates, maleic anhydrides, polyacrylamides, polyvinyl alcohols, polyethylene oxides, polyaspartates, polyglutamates, Examples thereof include polyalginate, starch, and cellulose. From the viewpoint of the effect of the present disclosure, a polyacrylate (particularly, sodium polyacrylate) SAP is preferable. In the absorbent body of the present disclosure, the primary and secondary absorbent layers can include, in addition to the SAP, an optional component, for example, a fiber, for example, pulp fiber. The absorbent core may include the fibers as a layer, for example, as a fabric (for example, a nonwoven fabric, a woven fabric, a knitted fabric, or the like). The cloth is preferably a hydrophilic cloth from the viewpoint of liquid absorbability. In the absorber of the present disclosure, it is preferable that 90 to 100% by mass of the SAP is composed of SAP particles having a particle size of 150 μm or more and less than 500 μm. Since the SAP particles having such a particle size distribution have a small and uniform particle size, they are easily held in the unevenness or the opening of the intermediate sheet. The particle size of the above SAP particles is measured according to the sieving test method described in JIS R 6002: 1998.

  The adhesive is not particularly limited, and any adhesive conventionally used in the art can be used. However, liquid transferability, bonding strength, texture, productivity, availability, etc. In view of this, a hot melt adhesive is preferred. Examples of hot melt adhesives include olefins such as polyethylene, polypropylene, and ethylene-α-olefin copolymers; ethylene-vinyl acetate copolymers; polyamides; styrene-butylene-styrene copolymers and styrene-isoprene- Thermoplastic elastomers such as styrene copolymers; reactive hot melts such as moisture-curable urethane prepolymers; In the absorber of the present disclosure, “intermittently bonded by an adhesive” means at least one of two mutually orthogonal directions in the plane of the absorber, such as a dot, a line, and a curve. The adhesive portion is formed by an adhesive applied in an arbitrary shape that is discontinuous in the direction. The number density and application amount of the bonded portion are selected so that the liquid absorbency of the absorber does not significantly decrease.

  The intermediate sheet has a plurality of grooves in which the concave portion and the convex portion on the upper surface are respectively depressed from the upper surface of the intermediate sheet toward the lower surface, and a plurality of grooves projecting from the lower surface of the sheet toward the upper surface. A plurality of grooves and a plurality of ridges extending in a first direction parallel to the longitudinal direction of the absorbent core, and at predetermined intervals in a second direction orthogonal to the first direction. Preferably, they are provided alternately. Since the ridges and grooves extend in parallel with the longitudinal direction (first direction) of the intermediate sheet, the diffusion of bodily fluids in the first direction can be promoted, and the absorption rate can be increased. Furthermore, the presence of the plurality of grooves and ridges on at least a part of the upper surface of the intermediate sheet can improve the flexibility of the intermediate sheet.

  Regarding the intermediate sheet, the height from the bottom of the continuous groove to the top of the continuous ridge on the upper surface (hereinafter referred to as “upper surface ridge height”) is preferably 0.1 to 5 mm, and more preferably 0 to 5 mm. .15 to 3 mm, more preferably 0.2 to 2 mm. In addition, the top of the ridge is located substantially at the center of the ridge in the second direction. On the upper surface side, the distance between the tops of adjacent ridges (hereinafter referred to as “upper surface ridge distance”) is preferably 0.25 to 5 mm, more preferably 0.5 to 3 mm, and more preferably 0.75 to 5 mm. 2 mm. If the upper surface side ridge height exceeds 5 mm, the thickness of the absorber increases, which is not preferable when a thin absorber is required. Depending on the particle size of the SAP particles, the ability of the intermediate sheet to hold the SAP particles can be further increased with the upper surface side ridge height and the upper surface side ridge interval in these ranges. In addition, the upper surface side ridge height and the upper surface side ridge interval in the above ranges can improve the flexibility of the intermediate sheet, increase the ability of the intermediate sheet to deform following the movement of the wearer, and provide an absorbent article. The wearing comfort can be improved. The above-mentioned upper surface side ridge height and upper surface side ridge interval are measured using a two-dimensional laser displacement meter. Examples of the two-dimensional laser displacement meter include a high-precision two-dimensional laser displacement meter LJ-G series (model: LJ-G030) manufactured by Keyence Corporation.

In the absorbent body of the present disclosure, as the core wrap sheet, those known in the art can be used, and are not particularly limited. The core wrap sheet is a spunlace nonwoven fabric containing pulp fibers or rayon fibers, or a pulp fiber and a rayon fiber. It is preferable that the spunlace nonwoven fabric contains both. From the viewpoint of improving the diffusivity in the in-plane direction of the core wrap sheet, the water absorption height after 5 minutes in a Krem water absorption test (artificial urine) according to JIS P8141 is 120 mm or more, and the water absorption ratio is 2.8 g / g or more. Preferably, there is. The core wrap sheet has a density distribution (dense / dense) in the cross-sectional width direction, the height direction, or both. When the core wrap sheet contains pulp fibers, from the viewpoint of liquid transfer from the core wrap sheet to the primary absorbent layer, the layer mainly composed of pulp fibers becomes relatively sparse, and at the same time, the pulp fiber layer It is preferable to adopt a structure in which the pulp fiber penetrates the adjacent relatively dense layer and actively exits. When rayon fibers are mainly used, it is preferable to adopt a structure in which density is intentionally provided in the width direction of the nonwoven fabric from the viewpoint of liquid diffusibility in the core wrap sheet and liquid transferability to the primary absorbent layer. . From the viewpoint of the balance between liquid diffusibility and liquid transferability, the basis weight is 25 g / m ² or more and less than 200 g / m ² , preferably 35 g / m ² or more and less than 150 g / m ² .

  FIG. 3, FIG. 4 (A) and FIG. 4 (B) show an embodiment of the intermediate sheet in the present disclosure. The intermediate sheet 6c has an upper surface 12 and a lower surface 13 opposite to the upper surface 12 in FIGS. 3, 4A and 4B, and protrudes from the lower surface 13 toward the upper surface 12. A plurality of ridges 14 and a plurality of grooves 15 recessed from the upper surface 12 toward the lower surface 13 are provided on the upper surface 12 side. The plurality of ridges and the plurality of grooves extend in a first direction parallel to the longitudinal direction D1 of the absorber, and are previously formed in a second direction (D2) orthogonal to both the first direction and the thickness direction of the intermediate sheet. They are provided alternately at predetermined intervals. From the viewpoint of improving the liquid diffusibility, it is preferable that the plurality of ridges and grooves extend continuously from one edge to the other edge of the intermediate sheet in the first direction of the intermediate sheet. Each groove 15 is formed between adjacent ridges and has a bottom 16. The bottom 16 of the groove 15 has a plurality of recesses 17 that are recessed from the upper surface to the lower surface and are provided discontinuously in the first direction. Each recess 17 has a peripheral wall 18 and a bottom 19. When the intermediate sheet is in the embodiment having the concave portion 17 in the bottom portion 16 of the continuous groove portion 15, the bottom portion 16 of the continuous groove portion 15 is hereinafter referred to as a first bottom portion, and the bottom portion 19 of the concave portion 17 is referred to as a second bottom portion. . In the embodiment shown in FIGS. 4A and 4B, the peripheral wall portion 18 includes a pair of first peripheral wall portions 18a, 18a extending in the first direction and a pair of second peripheral wall portions 18b extending in the second direction. , 18b, the pair of first peripheral wall portions 18a, 18a are provided so as to face each other, and the pair of second peripheral wall portions 18b, 18b are provided so as to face each other. Further, as schematically shown in FIGS. 4A and 4B, the intermediate sheets 6c are alternately provided on the lower surface 13 at predetermined intervals in a second direction orthogonal to the first direction. A plurality of ridges and a plurality of grooves. Each groove exists between adjacent ridges. The plurality of grooves and ridges provided on the lower surface 13 of the intermediate sheet 6c are located at positions opposite to the plurality of ridges and grooves provided on the lower surface 12 of the intermediate sheet 6c, respectively. Such an intermediate sheet can be manufactured by using, for example, an apparatus described in Japanese Patent No. 5829326. The intermediate sheet of the embodiment shown in FIG. 3, FIG. 4 (A) and FIG. 4 (B) is excellent in the ability to hold the SAP particles because the intermediate sheet is depressed in two stages when viewed from the top side. ing. When the SAP particles trapped in the grooves 15 and the recesses 17 swell because the intermediate sheet has a low tensile strength when wet, the unevenness of the intermediate sheet is deformed or partially torn in accordance with the swelling of the SAP particles. The anchor effect is caused by the SAP particles digging into the intermediate sheet. As a result, gel blocking can be suppressed, and the shape of the absorber can be further suppressed, so that the liquid absorbency and shape retention of the absorber can be further improved. Furthermore, since the intermediate sheet is flexible, it is possible to improve the wearing feeling of the wearer. The bodily fluid that has passed through the primary absorption layer moves toward the lower surface 13 while being diffused in the in-plane direction by the intermediate sheet, and is absorbed by the secondary absorption layer.

  In the embodiment shown in FIG. 4B, an opening 20 is formed in each of the first peripheral wall portions 18a of the concave portion 17 so as to penetrate the first peripheral wall portion 18a and communicate with the lower surface 13 of the intermediate sheet 6c. . Since the swelled SAP particles bite into the intermediate sheet at the opening portions while the opening portions expand in conformity with the swelling of the SAP particles, the SAP particle retention can be further improved. Furthermore, since the bodily fluid can transfer from the upper surface 12 side to the lower surface 13 side of the intermediate sheet 6c through the opening 20, the transfer of the bodily fluid from the upper surface 12 side to the lower surface 13 side of the intermediate sheet 6c can be promoted. . In the above embodiment, the opening 20 of the recess 17 is provided on the pair of first peripheral walls formed along the first direction, but the opening is formed along the second direction. It may be provided on a pair of second peripheral walls provided, or may be provided on any one of the peripheral walls.

  In the embodiment shown in FIGS. 4A and 4B, on the upper surface side, the distance from the height of the first bottom portion to the height of the second bottom portion on the upper surface side (hereinafter, “depth of upper surface side recess”) ) Is preferably 10 to 80%, more preferably 15 to 70%, and even more preferably 20 to 60% of the height of the upper surface side ridge. If the depth of the upper surface side concave portion is less than 10% of the height of the upper surface side ridge portion, a space having a sufficient volume to hold the SAP particles cannot be secured in the concave portion 17. If the upper surface side concave portion depth exceeds 80% of the upper surface side ridge height, the concave portion 17 becomes too deep, which increases the thickness of the absorber, which is not preferable when a thin absorber is required. The length of the concave portion in the first direction is preferably 0.25 to 5 mm, more preferably 0.5 to 3 mm, and more preferably 0.75 to 2 mm. The length of the concave portion in the second direction depends on the distance between the upper surface side ridges, but is preferably 0.25 to 5 mm, more preferably 0.5 to 3 mm, and more preferably 0.75 to 2 mm. The depth of the recess on the upper surface side, the length of the recess in the first direction, and the length of the recess in the second direction are measured using a two-dimensional laser displacement meter. Examples of the two-dimensional laser displacement meter include a high-precision two-dimensional laser displacement meter LJ-G series (model: LJ-G030) manufactured by Keyence Corporation.

  In the embodiment shown in FIG. 4 (B), in the interior space of the opening 20, the fiber spanned in the interior space and a part of the extended fiber are mixed. It is preferable that the space is not completely open. The opening ratio of the internal space of the opening is preferably 1 to 50%, more preferably 1.5 to 35%, and even more preferably 2.5 to 20%. Depending on the particle size of the SAP particles, the opening ratio in the above range can enhance the ability of the intermediate sheet to retain the SAP particles both before and after swelling. In particular, when the SAP particles swell, the swollen SAP particles easily penetrate into the opening, and the ability of the intermediate sheet to hold the swollen SAP particles can be increased. Depending on the particle size of the SAP particles, if the porosity of the inner space of the opening is less than 1%, the effect provided by the opening is insufficient, and if the porosity is 50% or more, the opening is insufficient. The SAP particles easily pass through the holes. However, the opening ratio of the internal space of the opening may be outside the above range and may be set arbitrarily according to the type and use of the absorbent article of the present disclosure.

In the present disclosure, the intermediate sheet is a sheet containing pulp fibers as a main component, that is, containing 50% by mass or more of pulp fibers. The pulp fiber content of the intermediate sheet is more preferably 70% by mass or more, still more preferably 90% by mass, and even more preferably 100% by mass. When the intermediate sheet contains pulp fibers as a main component, even when the basis weight of the intermediate sheet is set low, good hydrophilicity, liquid wicking property and liquid diffusibility can be exhibited. The average fiber length of the pulp fiber is not particularly limited, but preferably has an average fiber length of 1 mm to 10 mm, more preferably 2 mm to 3 mm, from the viewpoints of water absorption, water retention, flexibility, and ease of handling. preferable. The average length of the pulp fiber means the weight-weighted average length, and is measured by kajaaniFiberLab fiber properties (off-line) manufactured by metso automation. L (w) value. Examples of such pulp fibers include wood pulp (eg, softwood pulp and hardwood pulp) and non-wood pulp (eg, straw pulp, bagasse pulp, reed pulp, kenaf pulp, mulberry pulp, bamboo pulp, hemp pulp, cotton pulp (eg, cotton linter) Etc.). As long as the effects of the present invention are not impaired, the intermediate sheet may be made of, in addition to pulp fibers, other fibers such as thermoplastic synthetic fibers (eg, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate). Polyolefins such as copolymers, ethylene-acrylic acid copolymers, and ionomer resins; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polylactic acid; polyamides such as nylon; and natural fibers (for example, Wool, cotton, etc.), regenerated cellulose fibers (eg, rayon, acetate, etc.), and inorganic fibers (eg, glass fibers, carbon fibers, etc.). The basis weight of the intermediate sheet is preferably 9 to 100 g / m ² , and more preferably 12 to 60 g / m ² . The thickness of the intermediate sheet is preferably 0.1 to 5 mm, and more preferably 0.15 to 3 mm.
In the present disclosure, the basis weight and the thickness of the intermediate sheet are measured as follows.
Ten samples having a size of 100 mm × 100 mm were sampled, the mass of each sample was measured, and then the mass (g) of each sample was divided by the area (m ² ) of each sample to obtain the basis weight of each sample. Calculate the amount. The average value of the grammage of a total of 10 samples is calculated, and the average value is adopted as the grammage.
The thickness of the intermediate sheet is the PEACKCK dial gauge No. manufactured by Ozaki Seisakusho. 307 (measurement element diameter: 40 mm, pressure: 294 Pa).
The density of the intermediate sheet is calculated by dividing the grammage by the thickness.

Hereinafter, a method of manufacturing the intermediate sheet 6c having the above configuration will be described.
FIG. 5 shows an example of a manufacturing apparatus for manufacturing the intermediate sheet 6c, and FIG. 6 is a main portion schematically showing a pair of forming rolls of a forming apparatus provided in the intermediate sheet manufacturing apparatus. It is an expansion perspective view. FIG. 7 is an enlarged view of a main part schematically showing an arrangement of pins of a lower shaping roll, and FIG. 8 is an enlarged view of a main part showing an engagement state of an upper shaping roll and a lower shaping roll. It is. The production apparatus 50 illustrated in FIG. 5 is configured such that the raw sheet 51 to be processed into the intermediate sheet 6c is wound in a roll shape, and the unwinding apparatus 52 that unwinds the raw sheet 51 in the transport direction MD, and is unwound. The shaping apparatus 61 is provided with a shaping device 61 for performing a shaping process for forming the ridges, grooves, and concave portions as necessary on the raw sheet 51.

  The shaping device 61 includes a pair of upper and lower stretching rolls 62 and 63. As shown in FIG. 6, the upper stretching rolls 62 are arranged at regular intervals in the roll width direction. A plurality of ridges 62a are provided in parallel with each other along the outer peripheral surface of the roll 62, and a plurality of concave grooves 62b are provided between adjacent ridges 62a. On the other hand, the lower stretching roll 63 has a plurality of pins 63a provided on the outer peripheral surface so as to mesh with the concave grooves 62b of the upper stretching roll 62. As shown in FIG. 8, these pins 63a are arranged at regular intervals in the roll width direction so as not to come into contact with the protruding ridges 62a of the upper stretching roll 62. Are arranged substantially linearly at regular intervals along the outer peripheral surface. As shown in FIG. 7, the lower stretching roll 63 in this embodiment has a configuration in which a plurality of pins 63 a are arranged in a staggered manner on the outer peripheral surface of the lower stretching roll 63.

  In the shaping step, in the shaping device 61, the raw sheet 51 is inserted between a pair of upper and lower stretching rolls 62 and 63 which are rotating while meshing with each other, and the raw sheet 51 is meshed with the upper stretching roll. This is performed by extending between the protruding ridges 62a and the concave grooves 62b of 62 and the pins 63a of the lower stretching roll 63. The upper stretching roll 62 pushes a portion where the ridge 62a is in contact with the raw sheet 51 in the direction of the lower stretching roll 63, whereby the ridge portion 14 is formed. On the other hand, the lower stretching roll 63 is configured such that a plurality of pins 63a arranged in a line in the circumferential direction, the raw sheet 51 in contact with the distal end portion of the pin 63a, is placed in the same recess of the upper stretching roll 62. Push into the groove 62b. At this time, a portion of the raw sheet 51 that is pulled into the concave groove 62b in a non-contact state with the pin 63a becomes the groove portion 15. In addition, since the portion that has been in contact with the tip of the pin 62a is strongly pressed into the concave groove 62b and is shaped, the first peripheral wall portion 18a that extends in the direction in which the ridge portion 14 and the groove portion 15 extend, A concave portion 17 having a second peripheral wall portion 18a extending in the roll width direction and a bottom portion 19 is formed. At the time of forming the bottom portion 19 of the concave portion 17, when the upper stretching roll 9 and the lower stretching roll bite the raw sheet 51, the leading ends of the pins 62 a contact the raw sheet 51. The part is pushed into the groove 62b.

  In the web sheet 51, the portions that have been in contact with both ends in the width direction (roll width direction) of the tip portion of the pin 63 a are used when the ridge 62 a pushes the web sheet 51 in the direction of the stretching roll 63 below. With the help of the generated tension, the pin 63a pushes the fiber forming the first peripheral wall portion 8a or breaks the fiber to form a broken fiber having a broken end portion. Thereby, the opening 20 including the broken end portion of the broken fiber is formed in the concave portion 17. Note that some of the fibers remain in a state of being bridged in the internal space of the opening portion 20, and the broken ends of some of the broken fibers extend into the internal space. Here, the openings 20 are formed in the direction along the transport direction MD of the raw sheet 51, that is, in the rotation direction of the stretching rolls 62 and 63, and in the direction in which the ridges 14 and the grooves 15 extend. Because of this, the opening 20 is also formed on the first peripheral wall 18a along the direction in which the ridge 14 and the groove 15 extend. In the above embodiment, the concave portion 17 is formed in a substantially rectangular parallelepiped shape. However, the shape of the concave portion can be any shape such as a columnar shape or a prismatic shape. Using the sheet after the shaping step as the intermediate sheet 7 for an absorbent article, an absorbent article can be manufactured according to a known method.

Absorbent articles in which the absorbent body of the present disclosure is used are not particularly limited, but examples of the absorbent articles include absorbent articles mainly absorbing urine, for example, disposable diapers, urine absorbing pads, urination sheets for animals. Absorbent articles mainly absorbing menstrual blood, such as sanitary napkins and panty liners. The absorbent article is preferably an absorbent article that mainly absorbs urine, from the viewpoint that the effects of the present disclosure can be more exhibited.
In the absorbent article according to the present disclosure, the area of the absorbent article including the absorber is preferably 30 to 45 mN · m, more preferably 35 to 43 mN · m in the width (CD) direction (second direction). It has a rigidity value. When the bending stiffness value is in the above range, the absorbent article is easily deformed along the body of the wearer, is excellent in fitting property, and is excellent in wearing feeling. Further, the intermediate sheet of the present disclosure preferably has a softness of 50 mm or less, and more preferably has a softness of 30 mm or less. When the bending resistance exceeds 50 mm, the wearer tends to feel a hard wearing feeling.

  Hereinafter, the present disclosure will be described with examples, but the present disclosure is not limited to these examples.

[Intermediate sheet A]
A tissue paper having a basis weight of 16 g / m ² and a density of 0.31 g / cm ³ (manufactured by Nitku Corporation) was shaped by passing it through a pair of upper and lower stretching rolls. Each of the upper and lower stretching rolls has a ridge of 3 mm in height provided continuously on the outer circumferential surface of the rolls at 1.7 mm intervals in the width direction, and the engagement amount between the upper stretching roll and the lower stretching roll is 1 mm. The transport speed of the tissue paper was 35 m / min. The intermediate sheet A obtained by the shaping had a density of 0.04 g / cm ³ .

[Intermediate sheet B]
An intermediate sheet B was produced by shaping a tissue paper (manufactured by Nitku Corporation) having a basis weight of 16 g / m ² and a density of 0.31 g / cm ^{3 using} a shaping apparatus shown in FIGS. The shaping apparatus has a protruding ridge in which the upper stretching roll is continuously provided on the outer peripheral surface of the roll at 1.5 mm intervals in the width direction, and the lower stretching roll has a 0.7 mm long × horizontal side on the outer peripheral surface. It had a pin shape of 0.6 mm, and had pins arranged in a zigzag pattern at intervals of 1.5 mm in the width direction and at intervals of 2.27 mm in the circumferential direction. The engagement amount between the upper stretching roll and the lower stretching roll was 0.8 mm, and the tissue transport speed was 150 m / min. The intermediate sheet B obtained by the shaping had a density of 0.11 g / cm ³ .

[Intermediate sheet C]
The intermediate sheet C was the same as the intermediate sheet A.

[Intermediate sheets D to H]
The intermediate sheets D to H of the comparative example are as follows.
The intermediate sheet D was tissue paper manufactured by Nituku Corporation. The tissue paper was cut into a predetermined size without shaping, and used for producing an absorbent as described later.
The intermediate sheet E was prepared by applying two tissue papers to a hot melt adhesive (a thermoplastic elastomer based on styrene-butylene-styrene copolymer and styrene-isoprene-styrene copolymer manufactured by Henkel Japan Co., Ltd., coating amount 7 g / m ² in a spiral shape).
The intermediate sheet F was an air-through nonwoven fabric (2.8 dtex × 51 mm, manufactured by Unicharm Kokunon Non-Woven Co., Ltd.) composed of a composite fiber of polyethylene (PE) / polyethylene terephthalate (PET) = 40/60.
The intermediate sheet G was an air-through nonwoven fabric (4.4 dtex × 51 mm, manufactured by Unicharm Kokunon Non-Woven Co., Ltd.) composed of a composite fiber of polyethylene (PE) / polypropylene (PP) = 50/50.
The intermediate sheet H was air-laid pulp (manufactured by Oji Kinocross Co., Ltd.).
The above intermediate sheet was evaluated by the following test method. Table 2 shows the results. The basis weight, thickness, density, and Krem water absorption of the intermediate sheet were evaluated as described above.

[Permeability index]
The water permeability index of the intermediate sheet was determined using the apparatus shown in FIG.
An acrylic cylinder (inner diameter: 25 mmφ, wall thickness: 5 mm, height: about 30 mm) as a spacer 92 is fixed on a 100 mL measuring cylinder 91 (inner diameter: 27 mmφ), and placed on a balance 94 together with a metal tray 93. Was. The intermediate sheet 95 to be measured, which was carefully cut to a size of 10 × 10 cm so as not to spread between the fibers, was placed at the center of the hole of the spacer 92, and the display of the balance 94 was corrected to zero. An acrylic cylinder 96 (inner diameter: 25 mmφ, height: about 15 cm, glass filter roughness: G1) with a glass filter 97 as an inlet is placed from above the spacer 92, and is held by a clamp 98 while keeping the inlet horizontal. Then, the height was finely adjusted so that the mass load applied to the inlet of the acrylic cylinder 96 became 15 ± 2 g. The intermediate sheet 95 was in a state of being gently pressed down over the entire circular surface of the acrylic cylinder 96 inlet.
The water permeability index of the water-permeable substrate using such a device was measured by the following procedure.
A 10-liter container was charged with 60 g of sodium chloride, 1.8 g of calcium chloride dihydrate, 3.6 g of magnesium chloride hexahydrate and an appropriate amount of distilled water, and completely dissolved. Next, 15 g of a 1% by mass aqueous solution of poly (oxyethylene) isooctyl phenyl ether was added, and distilled water was further added to adjust the total mass of the aqueous solution to 6000 g. A test solution was prepared. 100 mL of the test solution was weighed and placed in the inlet while maintaining the solution height in the acrylic cylinder 96 at 4 to 6 cm. After permeating the whole amount, the amount of liquid (XmL) stored inside the measuring cylinder 91 was measured. The test liquid diffused to the outside via the intermediate sheet 95 was collected in the metal tray 93 (for the case where water permeation was not completed within 10 minutes after the start of charging, the liquid amount (XmL) at the time of 10 minutes was measured. ). The numerical value X of the liquid volume (XmL) was defined as the permeability index.

[Dry (DRY) tensile strength]
The dry strength was obtained by cutting the manufactured intermediate sheet into a 25 mm wide × 150 mm long so that the longitudinal direction was the machine direction, and then obtained the sample under the conditions of 20 ° C. and 65% relative humidity. It means the tensile force (N) at break when the sample in the dry state is measured by a Tensilon type tensile tester at a chuck interval of 100 mm and a tensile speed of 100 mm / min. The dry strength was measured using a Model 5564 tester manufactured by Instron Corporation, and the average value of five measurements was adopted.

[Wet tensile strength]
The wet strength was determined by cutting the manufactured intermediate sheet into a width of 25 mm and a length of 150 mm so that the longitudinal direction was the machine direction. After spraying distilled water equivalent to 250% of the sample mass equivalent to the above in a mist and leaving it to stand for 1 minute, under an atmosphere of 20 ° C. and a relative humidity of 65%, a chuck interval of 100 mm was used with a Tensilon type tensile tester, and a pulling speed was set. It means the tensile force (N) at break when measured at 100 mm / min. The wet strength was measured using a Model 5564 tester manufactured by Instron Corporation, and an average value of five measurements was adopted.

[Rigidity]
The bending resistance was determined by using a bending resistance tester CAN-1MCA (cantilever) manufactured by Daiei Kagaku Seiki Seisaku-sho, Ltd., and setting the size of the test piece to “(25 ± 1) mm × (250 ± 1) mm. ”Is changed to“ (25 ± 1) mm × (150 ± 1) mm ”in accordance with JIS L 1913: 2010,“ 6.7.3 41.5 Cantilever Method ”in General Nonwoven Fabric Testing Method. Measure at 5 mm / sec. As the bending resistance, an average value of five measurements on each side was adopted.

[Preparation of absorber]
Absorbers of Examples 1 to 3 and Comparative Examples 1 to 6 were produced from the intermediate sheet samples produced as described above, as described below.
First core wrap sheet (South Pacific Viscose, 1.7 dtex x 41 mm rayon fiber 100% upper layer (basis weight 12.5 g / m ² ), and International Paper pulp fiber 100% the intermediate layer (basis weight 30g / ^{m 2),} consists South Pacific viscose manufactured of 1.7 dtex × 41mm rayon fibers of 100% of the underlying (basis weight 12.5g / ^{m 2),} length 355mm , 140 mm wide and 55 g / m ² basis weight, a hot melt adhesive is applied while moving the core wrap sheet in the longitudinal direction, and a super absorbent polymer (SAP) discharge pipe and A polyacrylate-based superabsorbent polymer (SAP) was supplied from a superabsorbent polymer (SAP) supply device composed of a plurality of slide plates to a basis weight of 125 g / ^2, the discharge width: by dispersing in the longitudinal direction on the widthwise central portion of the core wrap sheets so that 100 mm, to form an SAP layer (primary absorbent layer). On the SAP layer, an intermediate sheet (355 mm in length and 100 mm in width) having both surfaces coated with a hot melt adhesive was stacked. While moving these laminates in the length direction of the laminate, a polyacrylate-based superabsorbent polymer (SAP) is laid on the intermediate sheet, similarly to the previously formed SAP layer, on a basis weight: Spraying was performed so as to be 125 g / m ² and discharge width: 100 mm, thereby forming an SAP layer (secondary absorption layer). On the SAP layer, a second core wrap sheet (1.7 dtex × 41 mm rayon fiber 100% upper layer manufactured by South Pacific Viscose Co., Ltd.) (a basis weight of 12.5 g / m ² ), an intermediate layer of 100% pulp fiber manufactured by International Paper Company (basis weight 30 g / m ² ), and a lower layer of a 100% rayon fiber of 1.7 dtex × 41 mm manufactured by South Pacific Viscose Company ( Spunlace nonwoven fabric having a basis weight of 12.5 g / m ² ) having a length of 355 mm, a width of 100 mm, and a basis weight of 55 g / m ² ). After being folded on the core wrap sheet of No. 2 above, the absorber is placed on a pair of press rolls (linear pressure 5 kN / m, clearance 1.0 mm, speed 20 m / min). By passing by adjusting the thickness by pressing to form the absorber. The SAP particles used for the absorbers of Example 3 and Comparative Example 4 were polyacrylic acid-based superabsorbent polymer particles having a water retention of 40 g / g manufactured by SDP Global Co., Ltd. The polyacrylic acid-based superabsorbent polymer particles having a water retention capacity of 40 g / g manufactured by SDP Global Co., Ltd. are sieved through seven types of sieves having openings of 850 μm, 600 μm, 500 μm, 355 μm, 300 μm, 250 μm and 150 μm. Accordingly, the content of the SAP particles having a particle size of 150 μm or more and less than 500 μm was analyzed to be 85% by mass, and the sieving amount of the 150 μm was about 0.1 to 0.2% by mass. The SAP particles used for the absorbers of Examples 1 and 2 and Comparative Examples 1 to 3, 5 and 6 were polyacrylate-based superabsorbent polymer particles having a water retention of 40 g / g manufactured by SDP Global Co., Ltd. It was sieved with a sieve having openings of 425 μm, and the content of SAP particles having a particle size of 150 μm or more and less than 500 μm was 98% by mass.

[Production of absorbent article]
A liquid permeable top sheet (an air-through nonwoven fabric manufactured by Unicharm Kokunon Non-Woven Co., Ltd.) is attached to the upper surface (the upper core wrap sheet side surface) of the absorber prepared as described above, and the lower surface (the lower core wrap) A liquid-impermeable backsheet (a polyethylene film manufactured by Tokuyama Corporation) was attached to the sheet-side surface) to produce an absorbent article sample.
The obtained absorbent article samples were evaluated by the following test methods, and the evaluation results are shown in Tables 1 and 2 below together with the physical properties of the intermediate sheet.

[Absorption time, rewetting amount and diffusion length]
(1) The absorbent article is set in a U-shaped device whose side view is substantially U-shaped. The absorbent article is set on the U-shaped device so that the central position in the longitudinal direction of the absorber and the central portion of the U-shaped device (the lowest position) are aligned.
<First cycle>
(2) Inject 70 mL of artificial urine (first time) at a rate of 70 mL / 10 seconds from the burette into the center of the absorber.
(3) The time from the start of the first injection of artificial urine to the time when there is no artificial urine in the U-shaped device is recorded as the absorption time (70 mL).
(4) Three minutes after the first injection of artificial urine, the contour (70 mL) of the region where artificial urine is diffused is recorded on the liquid impermeable sheet (BS) side of the absorbent article.
(5) Five minutes after the start of the first artificial urine injection, about 50 g of 100 mm x 100 mm filter paper is allowed to stand on the liquid-permeable sheet of the absorbent article centering on the artificial urine injection point. Further, a weight of 3.5 kg, 100 mm × 100 mm × 50 mm (height) is left thereon. Note that the weight of the filter paper is measured before being left on the liquid-permeable sheet.
(6) Eight minutes after the first injection of artificial urine, the weight is removed, the weight of the filter paper is measured, the weight of the filter paper before the test is subtracted, and the difference is defined as the re-wet amount (70 mL).
<Second cycle>
(7) Ten minutes after the start of the first injection of artificial urine, 70 mL of artificial urine (second time) is injected at a rate of 70 mL / 10 seconds from the burette into the central position of the absorber.
(8) Record the time from the start of the second injection of artificial urine until there is no artificial urine in the U-shaped device as the absorption time (140 mL).
(9) Three minutes after the start of the second artificial urine injection, the contour (140 mL) of the region where the artificial urine is diffused is recorded on the BS side of the absorbent article.
(10) Five minutes after the start of the second artificial urine injection, about 50 g of 100 mm x 100 mm filter paper is allowed to stand on the liquid permeable sheet of the absorbent article centering on the artificial urine injection point. Further, a weight of 3.5 kg, 100 mm × 100 mm × 50 mm (height) is allowed to stand thereon. Note that the weight of the filter paper is measured before being left on the liquid-permeable sheet.
(11) Eight minutes after the start of the second injection of artificial urine, the weight is removed, the weight of the filter paper is measured, the weight of the filter paper before the test is subtracted, and the difference is defined as the rewetting amount (140 mL).
<Third cycle>
(12) The operations of (7) to (11) are repeated, the absorption time (210 mL) is measured, and the contour (210 mL) is recorded on the BS side of the absorbent article.
<4th cycle>
(13) The operations of (7) to (11) are repeated, the absorption time (280 mL) is measured, and the contour (280 mL) is recorded on the BS side of the absorbent article.
(14) The diffusion length (70, 140, 210 mL) of artificial urine in the longitudinal direction of the absorbent article is measured from the contour (70, 140, 210 mL) of the region where artificial urine has diffused.
In addition, artificial urine was prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and about 1 g of a pigment: Blue No. 1 in 10 L of ion-exchanged water.

[Drainage time]
When the artificial urine remaining between the fibers of the topsheet migrated to the lower layer side, the time (second) for returning the blue wet topsheet to its original (before infiltration) color was measured.

[Absorbent shape retention]
(1) The absorber sample is placed on a horizontal table and cut into 150 mm along the longitudinal direction of the absorber with the center on one side of the absorber sample as the center.
(2) While keeping the absorber sample horizontal, 240 mL of artificial urine is injected into the center of the absorber using a beaker.
(3) Leave for 5 minutes.
(4) The absorber is put into a bag made of film (polybag with a zipper, CJ-4, polyethylene film, manufactured by Household Japan Co., Ltd.). At this time, the absorber sample is placed on the upper surface of the film, and the longitudinal and lateral ends of the absorber are placed from all sides to the center of the absorber so that the size after folding becomes 115 mm in width and 350 mm in length. Aim and fold.
(5) A bag containing the absorber sample is attached to a jig fixed in a drum of a centrifuge (a top discharge centrifuge H-130H manufactured by Kokusan Co., Ltd., drum inner diameter: 370 mm), and a centrifuge And centrifugal force is applied to the absorber sample at 430 rpm for 3 minutes. The mounting surface of the jig to which the bag containing the absorber is mounted is horizontal, and the center of the mounting surface is set to coincide with the rotation axis of the centrifuge. The bag containing the absorber sample is mounted on the mounting surface of the jig such that the center of the absorber sample is located on the center of the mounting surface of the jig. The absorber sample may be fixed by a hook-and-loop fastener or the like so that the absorber sample does not shift during centrifugation.
After the centrifugal treatment, the absorber sample is taken out, the liquid-permeable top sheet side is peeled off, and the unevenness of the swollen SAP particles in the primary absorption layer, that is, the shape retention of the primary absorption layer is evaluated according to the following grade. The average of the grades of the five samples is used as the evaluation result.
1. No deviation of the swollen SAP particles is observed.
2. Unevenness of SAP particles swollen in a part of the primary absorption layer is observed.
3. Unevenness of SAP particles swollen over a wide area in the plane of the primary absorption layer is observed.
4. The swollen SAP particles are unbalanced and clumped.

[Flexibility]
In the absorbent article of the present invention, the region of the absorbent article including the absorber has a bending rigidity of preferably 30 to 45 mN · m, more preferably 35 to 43 mN · m in the width direction. When the bending stiffness value is in the above range, the absorbent article is easily deformed along the body of the wearer, is excellent in fitting property, and is excellent in wearing feeling.
In this specification, the bending rigidity is measured according to the following procedure.
(1) In a constant temperature / humidity chamber (20 ± 2 ° C./60±5% RH), prepare a torque tester EX-0762 manufactured by Imada. The load cell is set to 50N for tension and compression, and the torque is set to 1N.
(2) Samples are cut out as shown in Table 1.
(3) At each end of the sample in the measurement direction, a cloth tape having a size of 50 mm × 20 mm is attached so that the jig interval is as shown in Table 1 so that the longitudinal direction is orthogonal to the measurement direction. Form grips at both ends in the measurement direction.
(4) The sample is mounted on a jig, and its maximum torque value (mN · m) is measured under the conditions shown in Table 1.
(5) The measurement is performed five times with different samples, and the average value thereof is adopted as the bending rigidity value.

  From Table 1 and Table 2, it can be seen that the absorbent according to the present invention and the absorbent article containing the same can maintain good liquid absorbency at a high level even when the liquid is repeatedly absorbed, and uneven distribution of SAP particles occurs. From the fact that it is difficult, it is understood that the liquid absorbency, shape retention and flexibility are improved in a well-balanced manner. Good form retention and flexibility provide an improved wearing comfort for the wearer.

DESCRIPTION OF SYMBOLS 1 Disposable diaper 2 Liquid permeable sheet 3 Absorber 6 Absorption core 6a Primary absorption layer 6b Secondary absorption layer 6c Intermediate sheet 7 Core wrap sheet 8 Adhesive 12 Top surface 13 Lower surface 14 Ridge 15 Groove 16 First bottom 17 Concave 18 Peripheral wall part 19 Second bottom part 20 Hole part 31 Main groove part 32 Subordinate groove part

Claims (12)

  An absorbent core having a longitudinal direction and a transversal direction, and a core wrap sheet, wherein the absorbent core includes primary and secondary absorbent layers containing superabsorbent polymer particles, and the primary and secondary absorbent layers An absorbent article for an absorbent article, comprising: an intermediate sheet disposed between the absorbent sheet and the intermediate sheet, the intermediate sheet having an upper surface in contact with the primary absorbent layer and a lower surface in contact with the secondary absorbent layer. The intermediate sheet has a concave portion and a convex portion on at least the upper surface, the average convex portion interval is 1 to 10 times the average particle size of the superabsorbent polymer particles, and the intermediate sheet is 0.5 to An absorber having a tensile strength of 7 N / 25 mm and having a tensile strength of less than 1 N / 25 mm in a wet state.   The absorber according to claim 1, wherein the intermediate sheet is a sheet containing 50% by mass or more of pulp fibers.   The absorber according to claim 1, wherein the intermediate sheet has, on a lower surface, concave portions and convex portions having an average interval between convex portions of 1 to 10 times the average particle size of the superabsorbent polymer particles.   The absorber according to any one of claims 1 to 3, wherein the intermediate sheet has a plurality of openings.   The absorber according to any one of claims 1 to 4, wherein 90 to 100% by mass of the superabsorbent polymer particles is composed of superabsorbent polymer particles having a particle size of 150 µm or more and less than 500 µm.   The absorber according to any one of claims 1 to 5, wherein the density of the intermediate sheet is lower than the density of the core wrap sheet.   The method according to any one of claims 1 to 6, wherein at least one of the primary and secondary absorbent layers and at least one of the intermediate sheet and the core wrap sheet are intermittently bonded by an adhesive. Absorber.   The absorber according to any one of claims 1 to 7, wherein the intermediate sheet has a water permeability index of greater than 90.   The concave portion and the convex portion of the upper surface of the intermediate sheet are, respectively, a plurality of groove portions recessed from the upper surface of the intermediate sheet toward the lower surface, and a plurality of projecting from the lower surface of the sheet toward the upper surface. A ridge, wherein the plurality of grooves and the plurality of ridges extend in a first direction parallel to a longitudinal direction of the absorbent core, and are predetermined in a second direction orthogonal to the first direction. The absorber according to any one of claims 1 to 8, wherein the absorber is provided alternately.   Each groove on the upper surface of the intermediate sheet has a groove bottom, and further provided on the groove bottom in a discontinuous manner with respect to the first direction, and a plurality of grooves recessed from the upper surface toward the lower surface. The absorber according to claim 9, comprising two concave portions.   The absorber according to claim 10, wherein the intermediate sheet has an opening in a second concave portion.   An absorbent article comprising the absorber according to any one of claims 1 to 11.

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