Patent Description:
There are known absorbent articles that exhibit excellent absorption performance (for example, absorption rate, and liquid return suppression) even when the absorbent articles repeatedly absorb bodily fluids. For example, Patent Literature <NUM> discloses an absorbent article including an absorbent core including superabsorbent polymer particles. In this absorbent article, the absorbent core is formed of a non-skin side layer on a non-skin facing surface side and a skin side layer on a skin facing surface side. The non-skin side layer includes a plurality of groove portions including a plurality of main groove portions that extend in a lengthwise direction and penetrate the non-skin side layer in a thickness direction, and a plurality of bases that extend in the lengthwise direction, and each of the plurality of main groove portions and each of the plurality of bases alternately extend in a lateral direction. The skin side layer includes a plurality of main groove portion corresponding portions and a plurality of base corresponding portions arranged at positions overlapping the plurality of main groove portions and the plurality of bases in the thickness direction, respectively. Both an average density of the superabsorbent polymer particles contained in each of the plurality of base portions and an average density of the superabsorbent polymer particles contained in each of the plurality of main groove portion corresponding portions are lower than an average density of the superabsorbent polymer particles contained in each of the plurality of base corresponding portions.

Further prior art in this technical field is disclosed in documents <CIT> and <CIT>.

An absorbent article as described in Patent Literature <NUM> includes a main groove portion and a base adjacent to the main groove portion in the non-skin side layer on the non-skin facing surface side. Therefore, the bodily fluid (for example: urine) that has reached the non-skin side layer through the skin side layer can be diffused in the main groove portion in the lengthwise direction, can be allowed to penetrate into the base and diffuse in the lateral direction, and can be transferred from the base to the base corresponding portion to be held in the base corresponding portion. Due to that, the entire absorbent core can be effectively used for absorption of the bodily fluid. Further, since the superabsorbent polymer particles are contained in the base and swell due to absorption of the bodily fluid, the shape of the main groove portion in the thickness direction can be maintained.

In such an absorbent article, part of the bodily fluid that has passed through the main groove portion corresponding portion before reaching the main groove portion is absorbed by the main groove portion corresponding portion, and can be held to the base corresponding portion from the main groove portion corresponding portion. In addition, the bodily fluid that has reached the main groove portion is reduced by the amount absorbed by the main groove portion corresponding portion, the ratio of the bodily fluid absorbed from the main groove portion to the base to the bodily fluid that is diffused in the main groove portion in the lengthwise direction increases. The bodily fluid that has absorbed to the base can be transferred from the base to the base corresponding portion and held in the base corresponding portion. Therefore, in a conventional absorbent article, it can be said that the ratio of the bodily fluid held in the base corresponding portion is high compared with a case of diffusion of the bodily fluid. Therefore, in a case where a bodily fluid is repeatedly absorbed, the degree of swelling of the superabsorbent polymer particles in the base becomes excessively large, the local thickness is increased, and there is a risk that the feeling of wearing may deteriorate.

An aspect of the present invention is to provide an absorbent article capable of maintaining absorption performance and a feeling of wearing even when a bodily fluid is repeatedly absorbed.

The present invention provides an absorbent article having a lengthwise direction, a lateral direction, and a thickness direction, the absorbent article comprising: an absorbent core that contains superabsorbent polymer particles, wherein the absorbent core has a skin facing surface, and a non-skin facing surface, and is formed of a skin side layer on a skin facing surface side, and a non-skin side layer on a non-skin facing surface side, the skin side layer includes a plurality of groove portions that extend in the lengthwise direction and penetrate in the thickness direction, and a plurality of bases that extend in the lengthwise direction, each of the plurality of groove portions and each of the plurality of bases alternately extend in the lateral direction, the plurality of groove portions includes a plurality of main groove portions that extend in the lengthwise direction, and a plurality of sub-groove portions that are present in communication with each of the plurality of main groove portions through base ends with predetermined spaces in a direction crossing each of the plurality of main groove portions, the non-skin side layer includes a plurality of groove portion corresponding portions and a plurality of base corresponding portions at positions that overlap the plurality of groove portions and the plurality of bases in the thickness direction, respectively, and a first average density of the superabsorbent polymer particles contained in each of the plurality of groove portion corresponding portions and the plurality of base corresponding portions is lower than a second average density of the superabsorbent polymer particles contained in each of the plurality of bases.

The absorbent article according to the present invention can maintain absorption performance and a feeling of wearing even when a bodily fluid is repeatedly absorbed.

Embodiments of the present invention relate to the following aspects.

An absorbent article having a lengthwise direction, a lateral direction, and a thickness direction, the absorbent article comprising:.

In the present absorbent article, an excreted bodily fluid is transferred in the lengthwise direction of the absorbent core through the main groove portions. The bodily fluid is absorbed into the inside of the absorbent core from the main groove portion and the sub-groove portion communicating with the main groove portion. Therefore, in the present absorbent article, even when the bodily fluid is repeatedly absorbed, the absorption performance, for example, absorption rate, can be maintained. The first average density of the superabsorbent polymer particles contained in the groove portion corresponding portion and the base corresponding portion is lower than the second average density of the superabsorbent polymer particles contained in the base potion. Therefore, while the bodily fluid absorbed into the groove portion corresponding portion is diffused in the lengthwise direction, part of the bodily fluid is transferred to the base corresponding portion. That is, since only part of the bodily fluid that has been transferred to the base corresponding portion in the bodily fluid absorbed into the groove portion corresponding portion is transferred to the base potion and can be held in the base potion, the superabsorbent polymer particles in the base potion can be prevented from swelling and becoming excessively large. As a result, in the present absorbent article, even when the bodily fluid is repeatedly absorbed, a local increase in the thickness is suppressed, and a feeling of wearing can be maintained.

The absorbent article according to aspect <NUM>, wherein
a ratio of the superabsorbent polymer particles contained in the plurality of groove portion corresponding portions and the plurality of base corresponding portions to the superabsorbent polymer particles contained in the entire absorbent core is less than <NUM>%.

In the present absorbent article, the ratio of the superabsorbent polymer particles contained in the plurality of groove portion corresponding portions and the plurality of base corresponding portions to the superabsorbent polymer particles contained in the entire absorbent core is less than <NUM>%. Therefore, since the superabsorbent polymer particles contained in the plurality of groove portion corresponding portions and the plurality of base corresponding portions can be sufficiently reduced compared with the superabsorbent polymer particles contained the base portions, the swelling of the groove portion corresponding portion and the base corresponding portion is suppressed. Therefore, in the present absorbent article, an increase in the thickness can be more reliably suppressed. Further, in the present absorbent article, the bodily fluid can be more rapidly diffused in the lengthwise direction and the lateral direction through the groove portion corresponding portion and the base corresponding portion.

The absorbent article according to aspect <NUM> or <NUM>, wherein.

In the present absorbent article, the average density of the superabsorbent polymer particles contained in the surface layer region is lower than the second average density. Therefore, the bodily fluid in the groove portion infiltrates into the surface layer region in which the average density of the superabsorbent polymer particles is lower, and thereby more rapidly permeates into the base potion. Therefore, the present absorbent article can rapidly absorb the bodily fluid in the groove portion. Further, the surface layer region in which there are few superabsorbent polymer particles is less likely to cause a phenomenon that the superabsorbent polymer particles that have absorbed water and swollen spill into the groove portion and block the groove portion. Therefore, the present absorbent article can maintain a rapid absorption rate even when the absorbent article repeatedly absorbs the bodily fluid.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein
in an excretion region of the absorbent core, a space between the plurality of main groove portions arranged on both sides in the lateral direction with a center of the absorbent core in the lateral direction interposed therebetween is <NUM>% or more and less than <NUM>% of a minimum length of the absorbent core in the lateral direction in the excretion region.

Since the space between the main groove portions is <NUM>% or more and less than <NUM>% of the minimum length of the absorbent core in the lateral direction in the excretion region, the present absorbent article can prevent the bodily fluid from concentrating in the center of the absorbent core, and can disperse the bodily fluid and more rapidly absorb the bodily fluid from the groove portions.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein
the plurality of base portions, the plurality of groove portion corresponding portions, and the plurality of base corresponding portions are integrated.

Since the bodily fluid can move more smoothly between the groove portion corresponding portion, the base corresponding portion, and the base potion, the bodily fluid can be more rapidly diffused.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein
an average density of the superabsorbent polymer particles contained in a central region including a center of each of the plurality of base portions in the lateral direction is higher than the second average density.

Since the average density of the superabsorbent polymer particles contained in the central region including the center of the base potion is higher than the second average density, the swelling of the base side surface in contact with the groove portion is suppressed, and the collapse of the groove portion can be suppressed. Therefore, in the present absorbent article, even in a case where the bodily fluid is repeatedly absorbed, the bodily fluid can more reliably permeate from the groove portion to the groove portion corresponding portion and be absorbed.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein
the plurality of base portions include.

The bodily fluid permeates from the main groove portion to the groove portion corresponding portion, and also permeates into the narrow portion through the sub-groove portion communicating with the main groove portion. Since the bodily fluid that has permeated from the groove portion to the groove portion corresponding portion and the narrow portion is absorbed into the inside of the absorbent core, the absorption performance, for example, absorption rate, can be maintained in the present absorbent article even when the bodily fluid is repeatedly absorbed.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein.

The first average density of the main groove portion corresponding portion is lower than the second average density. While the bodily fluid that has absorbed into the main groove portion corresponding portion is diffused in the lengthwise direction through the main groove portion corresponding portion, the bodily fluid is transferred to the base corresponding portion. That is, only part of the bodily fluid that has transferred to the base corresponding portion in the bodily fluid that has absorbed into the main groove portion corresponding portion is transferred to the base potion, and can be held in the base potion. Therefore, in the present absorbent article, the superabsorbent polymer particles in the base potion can be prevented from swelling and becoming excessively large.

The absorbent article according to aspect <NUM>, wherein
the first average density of the plurality of sub-groove portion corresponding portions is lower than the second average density.

Since the first average density of the sub-groove portion corresponding portion as well as the main groove corresponding portion is also lower than the second average density, the above-described effect can be more reliably obtained.

The absorbent article according to aspect <NUM>, wherein
each of the plurality of base portions is continuous from one end to the other end of the absorbent core in the lengthwise direction.

In the present absorbent article, since the central region is continuous from one end to the other end of the absorbent core in the lengthwise direction, the swelling of the base side surface that is in contact with the groove portion is suppressed across the entire region of the absorbent core in the lengthwise direction, the collapse of the groove portion can be suppressed, and the bodily fluid can be continuously and repeatedly diffused in the lengthwise direction.

Hereinafter, an absorbent article according to an embodiment will be described with reference to drawings.

In the present specification, unless otherwise specified, "viewing an object (for example, an absorbent article, an absorbent body, or an absorbent core) placed on a horizontal plane in an unfolded state from above or below the object in the thickness direction" will be referred to as a "plan view". In a case where the object is an absorbent article, viewing the absorbent article in the thickness direction from a top-surface sheet side in an unfolded state may be simply referred to as a "plan view". In a case where the object is an absorbent core, viewing the absorbent article in the thickness direction from a non-skin facing surface side of the absorbent core in an unfolded state may be simply referred to as a "plan view".

Various directions and the like used in the present specification are as follows, unless otherwise specified. The "longitudinal direction" refers to "a direction in which the length of a longitudinally long object in a plan view is long", the "lateral direction" refers to "a direction in which the length of the longitudinally long object in a plan view is short", and the "thickness direction" refers to "a direction vertical to the object placed on a horizontal plane in an unfolded state". The longitudinal direction, the lateral direction, and the thickness direction are in a relationship that is orthogonal to each other. It should be noted that, although each direction includes two opposite directions, when shown in the drawings, there is a case where only one direction is shown with respect to a direction orthogonal to the paper surface.

In the present specification, unless otherwise specified, in the thickness direction of the absorbent article, a "proximal side relative to the skin surface of the wearer while the absorbent article is put on" is referred to as a "skin facing surface side", and a "distal side relative to the skin surface of the wearer while the absorbent article is put on" is referred to as a "non-skin facing surface side". In the present specification, the "skin facing surface side surface" and the "non-skin facing surface side surface" of various members (for example, a top-surface sheet, an absorbent body, and a back-surface sheet) that constitute the absorbent article are simply referred to as a "skin facing surface" and a "non-skin facing surface," respectively.

In the present specification, the "main groove portion" means not only a groove portion that extends in a direction parallel to the longitudinal direction, but also a groove portion that extends along the longitudinal direction. An angle formed between the main groove portion and the longitudinal direction is preferably less than <NUM>°, more preferably less than <NUM>°, and even more preferably less than <NUM>°. The main groove portion can extend linearly, or non-linearly, for example, in a curved shape. In the present specification, the width of the main groove portion means the length of the main groove portion in a direction orthogonal to a direction in which the main groove portion extends in an object portion.

In the present specification, the "sub-groove portion" means not only a groove portion that extends in a direction parallel or substantially parallel to the lateral direction, but also a groove portion that extends in a direction other than the longitudinal direction. An angle formed between the sub-groove portion and the main groove portion (or the tangent line of the main groove portion) at a portion (base end) where the sub-groove portion communicates with the main groove portion is preferably <NUM>° or more, more preferably <NUM>° or more, and even more preferably <NUM>° or more. The sub-groove portion can extend linearly, or non-linearly, for example, in a curved shape. In the present specification, the width of the sub-groove portion means the length of the sub-groove portion in a direction orthogonal to a direction in which the sub-groove portion extends in the object portion.

In the present specification, the terms "front waist region," "back waist region," and "crotch region" are used in a case where the absorbent article is a disposable diaper, and the meanings are as follows. In a pull-on disposable diaper, the front waist region means a region interposed between a pair of joining portions at both lateral end portions that join a front body and a back body in the front body, and the back waist region means a region interposed between the pair of joining portions in the back body. The crotch region means a region between the front waist region and the back waist region. The crotch region also corresponds to a region interposed between the pair of leg openings. In a tape-type disposable diaper, the waist region and the crotch region are partitioned in a fixed state in which the tip ends of a pair of tape fasteners are fixed so as to be adjacent to a predetermined fixing region for the tape fastener. Specifically, the waist region is determined based on a pair of overlapping portions in which a waist forming member of the front body and a waist forming member of the back body overlap with each other in the absorbent article in the above fixed state. The front waist region means a region between the pair of overlapping portions in the front body of the absorbent article. Similarly, the back waist region means a region between the pair of overlapping portions in the back body of the absorbent article. The crotch region means a region between the front waist region and the back waist region.

<FIG> are views showing a configuration example of an absorbent article <NUM> according to a first embodiment, specifically, a disposable diaper. <FIG> is a plan view of the absorbent article according to the first embodiment. <FIG> is a plan view of an absorbent body of the absorbent article according to the first embodiment. <FIG> is a cross-sectional view taken along a line III-III in <FIG> according to the first embodiment. <FIG> is a plan view of an absorbent core of the absorbent article according to the first embodiment. <FIG> is a cross-sectional view of the absorbent body taken along a line V-V in <FIG> according to the first embodiment. <FIG> is a schematic view showing the flow of a bodily fluid in a cross section of the absorbent body taken along a line III-III in <FIG> according to the first embodiment.

As shown in <FIG>, the absorbent article <NUM> includes a liquid-permeable sheet <NUM>, a liquid-impermeable sheet <NUM>, and an absorbent body 7A that is arranged between the liquid-permeable sheet <NUM> and the liquid-impermeable sheet <NUM>. In a lengthwise direction L, the absorbent article <NUM> is divided into three regions: a front waist region FW, a back waist region RW, and a crotch region C between the front waist region FW and the back waist region RW. The absorbent body 7A is arranged across the three regions. The absorbent article <NUM> further includes a pair of leakproof walls <NUM> including an elastic member <NUM>, a fixed portion <NUM> that fixes the leakproof wall <NUM> to the liquid-permeable sheet <NUM>, an elastic member <NUM> arranged around the leg portion, a tape fastener <NUM>, and the like. It should be noted that these are well-known in the art and will not be described here.

As shown in <FIG> and <FIG>, the absorbent body 7A has a lengthwise direction L, a lateral direction W, and a thickness direction T. The absorbent body 7A includes an absorbent core 9A having a skin facing surface <NUM> and a non-skin facing surface <NUM>, and a core wrap <NUM> formed of a tissue that covers the skin facing surface <NUM> and the non-skin facing surface <NUM>. It should be noted that, in the present embodiment, since the lengthwise direction, the lateral direction, and the thickness direction of the absorbent article <NUM> are the same as the directions of the absorbent body 7A, the lengthwise direction L, the lateral direction W, and the thickness direction T are also used as the directions of the absorbent article <NUM>. As the core wrap <NUM>, a hydrophilic nonwoven fabric may be used.

The absorbent core 9A includes the skin side layer 6A on the skin facing surface side and the non-skin side layer <NUM> on the non-skin facing surface side. The skin side layer 6A includes a plurality of groove portions <NUM> that penetrate the skin side layer 6A in the thickness direction T, and a base potion 20A that is located between the plurality of groove portions <NUM>. As shown in <FIG>, the absorbent core 9A has a first end portion <NUM> and a second end portion <NUM> that are arranged at both end portions in the lengthwise direction L and have the same length in the lateral direction W, and a constricted portion <NUM> that is arranged at a central part in the lengthwise direction L and has a length in the lateral direction W shorter than the lengths of the first end portion <NUM> and the second end portion <NUM>. The first end portion <NUM> and the constricted portion <NUM>, and the second end portion <NUM> and the constricted portion <NUM> are respectively connected to each other through inclined sides inclined toward the inner side in the lateral direction W toward the constricted portion <NUM>. The groove portion <NUM> and the base potion 20A have a shape extending along the lengthwise direction L and alternately extend in the lateral direction W. The groove portions <NUM> are arranged so as to be line-symmetric with respect to a central axis line VL that bisects the absorbent core 9A in the lateral direction W.

The groove portions <NUM> have a plurality of main groove portions <NUM> and a plurality of sub-groove portions <NUM>. The plurality of main groove portions <NUM> are respectively recessed in the thickness direction T of the absorbent core 9A from the skin facing surface <NUM> toward the non-skin facing surface <NUM>, and extend in the lengthwise direction L. In the case of the first embodiment, four main groove portions <NUM> are evenly arranged in the lateral direction W with an end <NUM> of the first end portion <NUM> and an end <NUM> of the second end portion <NUM> serving as base ends. Among the four main groove portions <NUM> at the first end portion <NUM> and the second end portion <NUM>, two inner main groove portions have leading ends respectively towards the first end portion <NUM> and towards the second end portion <NUM> with respect to the constricted portion <NUM>.

The two main groove portions <NUM> located on the outer sides of the second end portion <NUM> in the lateral direction W extend to be inclined toward the inner side in the lateral direction W toward the constricted portion <NUM>, and have leading ends at positions along the lengthwise direction L. The two main groove portions <NUM> located on the outer sides of the first end portion <NUM> in the lateral direction W extend to be inclined toward the inner side in the lateral direction W toward the constricted portion <NUM>, and extend along the lengthwise direction L again in the constricted portion <NUM>. Further, the two main groove portions <NUM> are inclined toward the outer side in the lateral direction W so as to avoid the leading ends of the two main groove portions <NUM> that extend from the second end portion <NUM> and have leading ends at positions along the lengthwise direction L. A substantially cross-shaped cross groove portion <NUM> is arranged between the leading ends of the two main groove portions <NUM>, that is, at the center of the absorbent core 9A in the lateral direction W.

It is preferable that a space between the main groove portions <NUM> in the lateral direction W is <NUM>% or more and less than <NUM>% of the minimum length of the absorbent core 9A the lateral direction W in an excretion region. The space between the main groove portions <NUM> is the length between the centers of the two main groove portions <NUM>. In the case of the first embodiment, the space between the main groove portions <NUM> in the lateral direction W is a space L1 between the two main groove portions <NUM> that extend from the first end portion <NUM> in the constricted portion <NUM>. The minimum length of the absorbent core 9A in the lateral direction W is a lateral length L2 of the constricted portion <NUM>. Therefore, it is preferable that the length L1 is <NUM>% or more and less than <NUM>% of the length L2.

As shown in <FIG>, the main groove portion <NUM> includes a main groove bottom face <NUM> that comes into contact with the non-skin side layer <NUM>, and a main groove side surface <NUM> that is in contact with the base potion 20A on the outer side of the main groove bottom face <NUM> in the lateral direction W. The main groove bottom face <NUM> is the skin side surface of the non-skin side layer <NUM>. The main groove portion <NUM> has a width that is preferably <NUM> to <NUM> times, more preferably <NUM> to <NUM> times, and even more preferably <NUM> to <NUM> times as much of the thickness of the absorbent body 7A. When the width of the main groove portion <NUM> is within the above range, the main groove portion <NUM> easily maintains its water flow function after the absorbent article <NUM> absorbs the bodily fluid.

In the present specification, unless otherwise specified, the thickness (mm) of an object (for example, an absorbent body or an absorbent core) is measured as follows. FS-60DS (the measurement surface: <NUM> (in diameter), the measurement pressure: <NUM>/cm<NUM>), manufactured by Daiei Kagaku Seiki MFG, Co. , is prepared, five different portions of the object are applied with pressure under the standard condition (the temperature: <NUM>±<NUM>, the relative humidity: <NUM>±<NUM>%), the thickness at each of the portions after <NUM> seconds from the pressure application is measured, and the average value of the five measurement values is used as the thickness of the absorbent body. It should be noted that in the absorptiveness test described below, also in a case of measuring the thickness of the absorbent article after the second cycle, measurement is performed in the same manner.

As shown in <FIG>, the base end of each of the plurality of sub-groove portions <NUM> communicates with the main groove portion <NUM>, and the leading end extends in the lateral direction W and has a leading end. In the case of the first embodiment, the sub-groove portion <NUM> extends along the lateral direction W from the first end portion <NUM> to the constricted portion <NUM> and from the second end portion <NUM> to the constricted portion <NUM> even in a range where the main groove portion <NUM> is inclined. As shown in <FIG>, the sub-groove portion <NUM> is recessed in the thickness direction T of the absorbent core 9A from the skin facing surface <NUM> toward the non-skin facing surface 17and extends in the lateral direction W. The depth of the sub-groove portion <NUM> is the same as the depth of the main groove portion <NUM>. The sub-groove portion <NUM> has a sub-groove bottom face <NUM> that is in contact with the non-skin side layer <NUM> and a sub-groove side surface <NUM> that is in contact with the base potion 20A on the outer side of the sub-groove bottom face <NUM> in the lateral direction W. The sub-groove bottom face <NUM> is the skin side surface of the non-skin side layer <NUM>. Usually, the sub-groove portions <NUM> are formed on both sides of the main groove portion <NUM>. However, in the main groove portions <NUM> at two ends located on the outermost side of the absorbent core 9A in the lateral direction W, the sub-groove portions <NUM> on the outer sides of the main groove portions <NUM> can be omitted.

In the present specification, in a case where the main groove bottom face <NUM> and the sub-groove bottom face <NUM> are not particularly distinguished from each other, the main groove bottom face <NUM> and the sub-groove bottom face <NUM> will be referred to as a groove bottom face <NUM>. The opening of the groove portion <NUM> that faces the groove bottom face <NUM> is blocked with the core wrap <NUM>.

As shown in <FIG> and <FIG>, the base potion 20A has a narrow portion <NUM> located between facing sub-groove side surfaces <NUM> that extend from the main groove portions <NUM> located on both sides of the base potion 20A toward the base potion 20A, and a wide portion <NUM> located between the main groove side surfaces <NUM>. A top surface <NUM> of the base potion 20A is the skin facing surface <NUM>. The top surface <NUM> comes into contact with the main groove side surface <NUM> and the sub-groove side surface <NUM>, respectively, on the outer side in the lateral direction W. The main groove side surface <NUM> and the sub-groove side surface <NUM> also serve as base side surfaces <NUM>. The sub-groove portions <NUM> that form the narrow portion <NUM> need to face each other, but the sub-groove portion <NUM> on the opposite side to the narrow portion <NUM> does not have to extend from the same position of the main groove portion <NUM>. Each of the plurality of base portions 20A is continuous from the first end portion <NUM> to the second end portion <NUM> through the constricted portion <NUM>. The plurality of base portions 20A that are adjacent to each other through the groove portions <NUM> are continuous between the leading ends of the main groove portions <NUM> in the constricted portion <NUM> (<FIG>).

As shown in <FIG>, the non-skin side layer <NUM> includes, in the thickness direction T, a plurality of main groove portion corresponding portions <NUM> at positions that overlap the plurality of main groove portions <NUM>, a plurality of sub-groove portion corresponding portions <NUM> at positions that overlap the plurality of sub-groove portions <NUM>, and a plurality of base corresponding portions <NUM> at positions that overlap the plurality of base portions 20A. In a case where the main groove portion corresponding portion <NUM> and the sub-groove portion corresponding portion <NUM> are not particularly distinguished from each other, the main groove portion corresponding portion <NUM> and the sub-groove portion corresponding portion <NUM> will be referred to as a groove portion corresponding portion <NUM>. The non-skin facing surface <NUM> of the non-skin side layer <NUM> is flat. The plurality of base portions 20A, the plurality of groove portion corresponding portions <NUM>, and the plurality of base corresponding portions <NUM> may be integrally formed.

The thickness of both the skin side layer 6A and the non-skin side layer <NUM> is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and even more preferably <NUM> to <NUM>. It should be noted that the thickness of each of the skin side layer 6A and the non-skin side layer <NUM> can be measured in the following non-contact method using the laser displacement meter (for example, high-precision two-dimensional laser displacement meter LJ-G series (model: LJ-G030) manufactured by Keyence Corporation). The absorbent core 9A which is obtained by blowing a cold spray onto the absorbent article <NUM> so as to peel off the liquid-permeable sheet <NUM>, the liquid-impermeable sheet <NUM>, and the core wrap <NUM>, is cut into a size of <NUM> × <NUM>, and is used as a sample. The sample is placed on a horizontal measurement table in a manner such that the skin facing surface <NUM> having the plurality of groove portions <NUM> and the plurality of base portions 20A formed thereon faces upward, the displacement from the measurement table is measured by the laser displacement meter for five different base portions 20A, and the average value of the five measurement values is set as Ax (mm). Similarly, the displacement from the measurement table is measured by the laser displacement meter for five different groove portions <NUM> (main groove portions <NUM>), and the average value of the five measurement values is set as Ay (mm). The thickness of the non-skin side layer <NUM> is Ay (mm), and the thickness of the skin side layer 6A is calculated from the difference between Ax (mm) and Ay (mm).

The absorbent core 9A includes water-absorbent fibers <NUM> and superabsorbent polymer particles (SAP) <NUM>, and has a function of absorbing and holding the bodily fluid discharged to the absorbent article <NUM>. A ratio of the superabsorbent polymer particles contained in the non-skin side layer (main groove portion corresponding portions <NUM>, base corresponding portions <NUM>) <NUM> to the superabsorbent polymer particles contained in the entire absorbent core 9A is <NUM>% or more and less than <NUM>%, preferably <NUM>% or more and less than <NUM>%, and more preferably <NUM>% or more and <NUM>% or less.

In the first embodiment, the average basis weight of the water-absorbent fibers in both the skin side layer 6A and the non-skin side layer <NUM> is preferably <NUM> to <NUM>/m<NUM>, and more preferably <NUM> to <NUM>/m<NUM>. The basis weight is measured according to the following measurement method. The sheet is cut into a size of <NUM> × <NUM> and is used as a sample. The mass is measured after a drying treatment in an atmosphere of <NUM> or higher. Next, the measured mass is divided by the area of the sample to calculate the basis weight of the sample. The value obtained by averaging the basis weights of <NUM> samples is defined as the basis weight of the sheet. The average basis weight of the superabsorbent polymer particles in the non-skin side layer <NUM> is preferably <NUM> to <NUM>/m<NUM>, and more preferably <NUM> to <NUM>/m<NUM>, and the average basis weight of the superabsorbent polymer particles in the skin side layer 6A is preferably <NUM> to <NUM>/m<NUM>, and more preferably <NUM> to <NUM>/m<NUM>.

The average density (hereinafter, referred to as "first average density") of the superabsorbent polymer particles in the non-skin side layer (main groove portion corresponding portions <NUM>, base corresponding portions <NUM>) <NUM> is smaller than the average density (hereinafter, referred to as "second average density") of the superabsorbent polymer particles in the skin side layer (base portions 20A) 6A. In the case of the first embodiment, the first average density is, for example, <NUM> to <NUM>/cm<NUM>, <NUM> to <NUM>/cm<NUM>, or <NUM> to <NUM>/cm<NUM>, and the second average density is, for example, <NUM> to <NUM>/cm<NUM>, <NUM> to <NUM>/cm<NUM>, or <NUM> to <NUM>/cm<NUM>.

A method of measuring the average density of the superabsorbent polymer particles is as follows. Five samples having a predetermined length and a predetermined width are cut out from the absorbent core 9A (for example, <NUM> × <NUM>), the superabsorbent polymer particles contained in each sample are selected, the total mass of the superabsorbent polymer particles contained in each sample is measured, and the measurement value is divided by the volume of the sample obtained by the thickness of the sample and the area of the sample to obtain the average value.

In the present specification, in a case of evaluating the average density of the superabsorbent polymer particles in each of the portions of the base potion 20A and the non-skin side layer (main groove portion corresponding portion <NUM>, base corresponding portion <NUM>) <NUM> in the absorbent core 9A, the following method may be employed. For example, the absorbent article <NUM> serving as a sample is impregnated with liquid nitrogen so as to be frozen, and then, the absorbent article <NUM> is cut with a razor in the thickness direction T, so as to obtain a cross section at the surface crossing the direction in which the main groove portion <NUM> extends. Next, the temperature of the sample is returned to room temperature, and a cross-sectional image with a magnification of <NUM> times is obtained by using an electron microscope (for example, VE7800 manufactured by Keyence Corporation). In the cross-sectional image, the degrees of the average density of the superabsorbent polymer particles at each of the portions of the base potion 20A, the main groove portion corresponding portion <NUM>, and the base corresponding portion <NUM> is visually evaluated. It should be noted that, in a case of evaluating the degrees of the average density of the superabsorbent polymer particles in the sub-groove portion corresponding portion <NUM> and the average density of the superabsorbent polymer particles in each of the base potion 20A and the base corresponding portion <NUM>, evaluation can be performed using a cross-sectional image in the surface crossing the direction in which the sub-groove portion <NUM> extends in the same method as described above, instead of the above method.

Since the absorbent article <NUM> has the groove portions <NUM> in the skin side layer 6A and the average density of the superabsorbent polymer particles is in the relationship of the non-skin side layer <NUM> < the skin side layer 6A, the bodily fluid moves in the absorbent core 9A as shown in <FIG>, for example.

Since the absorbent article <NUM> includes the groove portion <NUM> and the base potion 20A in which the density of the superabsorbent polymer particles is high on the skin side layer 6A, and the water absorption rate of the superabsorbent polymer particles is not high, most of the bodily fluid that has reached the core wrap <NUM> is immediately passed to the groove portion <NUM>. The bodily fluid that has passed to the groove portion <NUM> is transported in the lengthwise direction L of the absorbent core 9A through the main groove portion <NUM>, and is absorbed into the inside of the absorbent core 9A from the main groove portion <NUM> and the sub-groove portion <NUM> communicating with the main groove portion <NUM>. That is, the bodily fluid permeates from the main groove bottom face <NUM> to the main groove portion corresponding portion <NUM>, and from the sub-groove bottom face <NUM> to the sub-groove portion corresponding portion <NUM>, and also permeates from the main groove side surface <NUM> to the wide portion <NUM>, and from the sub-groove side surface <NUM> to the narrow portion <NUM>. Further, while the bodily fluid that has permeated into the main groove portion corresponding portion <NUM> and the sub-groove portion corresponding portion <NUM> is diffused through the base corresponding portion <NUM>, the bodily fluid can be sucked up to the base potion 20A containing a large amount of superabsorbent polymer particles and having a high density, and held in the superabsorbent polymer particles. Therefore, even when the bodily fluid is repeatedly absorbed, the absorbent article <NUM> can maintain the absorption performance, for example, absorption rate by repeating the above-described cycle.

The first average density of the superabsorbent polymer particles contained in the groove portion corresponding portion <NUM> and the base corresponding portion <NUM> is lower than the second average density of the superabsorbent polymer particles contained in the base potion 20A. The absorption rate of the superabsorbent polymer particles is low, and the water absorption and swelling of the superabsorbent polymer particles, which are blended in the fiber matrix and compressed at a high density, is further suppressed. Therefore, since the swelling of the groove portion corresponding portion <NUM> is suppressed, the bodily fluid in the groove portion <NUM> permeates more into the groove portion corresponding portion <NUM>. Further, since the swelling of the base corresponding portion <NUM> is suppressed, the bodily fluid absorbed by the groove portion corresponding portion <NUM> is diffused in the lengthwise direction L through the groove portion corresponding portion <NUM>. While the bodily fluid is diffused in the lengthwise direction L, part of the bodily fluid is transferred to the base corresponding portion <NUM>. The bodily fluid that has transferred to the base corresponding portion <NUM> can be sucked up to the base potion 20A and held in the base potion 20A. Therefore, in the absorbent article <NUM>, when the diffusion rate is increased with respect to the sucking rate of the base potion 20A by suppressing the swelling of the groove portion corresponding portion <NUM> and the base corresponding portion <NUM>, the superabsorbent polymer particles of the base potion 20A can be prevented from swelling and becoming excessively large. That is, in the absorbent article <NUM>, when the bodily fluid is diffused in a wider range, a local increase in the thickness can be suppressed. As a result, in the absorbent article <NUM>, the entire thickness is prevented from increasing even when the bodily fluid is repeatedly absorbed, and a feeling of wearing can be maintained.

The ratio of the superabsorbent polymer particles contained in the non-skin side layer <NUM> to the superabsorbent polymer particles contained in the entire absorbent core 9A is <NUM>% or more and less than <NUM>%. In the case of the above-described range, since the superabsorbent polymer particles contained in the plurality of groove portion corresponding portions <NUM> and the plurality of base corresponding portions <NUM> can be sufficiently reduced compared with the base potion 20A, the swelling of the groove portion corresponding portions <NUM> and the base corresponding portions <NUM> can be suppressed. Therefore, in the absorbent article <NUM>, an increase in the thickness can be more reliably suppressed. Further, in the absorbent article <NUM>, the bodily fluid can be more rapidly diffused in the lengthwise direction L and the lateral direction W through the groove portion corresponding portion <NUM> and the base corresponding portion <NUM>.

The space L1 between the main groove portions <NUM> in the lateral direction W is <NUM>% or more and less than <NUM>% of the minimum length L2 of the absorbent core 9A in the lateral direction W in the excretion region. The absorbent article <NUM> can prevent the bodily fluid from concentrating at the center of the absorbent core 9A, and can disperse the bodily fluid and more rapidly absorb the bodily fluid from the groove portion <NUM>. Since the plurality of base portions 20A, the plurality of groove portion corresponding portions <NUM>, and the plurality of base corresponding portions <NUM> are integrally formed, the bodily fluid can be more smoothly transferred between the groove portion corresponding portions <NUM>, the base corresponding portions <NUM>, and the base portions 20A, and thus the bodily fluid can be more rapidly diffused.

Description has been made on a case where the average density of the superabsorbent polymer particles in the sub-groove portion corresponding portion <NUM> is the first average density that is lower than the second average density. However, the present invention is not limited thereto, and the average density may be higher than the first average density and equal to or lower than the second average density. Even in a case where the average density of the superabsorbent polymer particles in the sub-groove portion corresponding portion <NUM> is higher than the first average density, the non-skin side layer <NUM> has the main groove portion corresponding portion <NUM> in addition to the base corresponding portion <NUM>, and thus the same effect as in the above embodiment can be obtained.

Hereinafter, an absorbent article according to a second embodiment will be described. The configurations similar to those of the first embodiment are denoted by similar reference signs, and the description thereof will be omitted. <FIG> is a cross-sectional view taken along a line III-III in <FIG>. <FIG> is a plan view of an absorbent core 9B of the absorbent article <NUM>.

An absorbent body 7B includes the absorbent core 9B and the core wrap <NUM>. The absorbent core 9B is formed of a skin side layer 6B and a non-skin side layer <NUM>, and the skin side layer 6B includes a plurality of groove portions <NUM> and a plurality of base portions 20B. Each of the base portions 20B includes a surface layer region <NUM> and a central region <NUM>. The surface layer region <NUM> includes the top surface <NUM> and the base side surface <NUM> and has a constant thickness from the top surface <NUM> and the base side surface <NUM> into the base potion 20B. The thickness of the surface layer region <NUM> is, for example, in a range of <NUM>/<NUM> of the length of the base potion 20B in the lateral direction W. The average density (hereinafter, referred to as "third average density") of the superabsorbent polymer particles contained in the surface layer region <NUM> is lower than the second average density. The third average density is approximately <NUM>% of the second average density.

The central region <NUM> includes the centers of the plurality of base portions 20B in the lateral direction W, and is in contact with the surface layer region <NUM>. The base side surface <NUM> side and the top surface <NUM> side of the central region <NUM> is in contact with the surface layer region <NUM>. The central region <NUM> is continuous from the end <NUM> of the first end portion <NUM> to the end <NUM> of the second end portion <NUM> through the constricted portion <NUM>. The length of the central region <NUM> in the lateral direction W is, for example, in a range of <NUM>/<NUM> of the length of the base potion 20B in the lateral direction W. The average density (hereinafter, referred to as "fourth average density") of the superabsorbent polymer particles contained in the central region <NUM> is higher than the second average density. The fourth average density is approximately <NUM>% of the second average density. The presence of the surface layer region <NUM> and the central region <NUM> can be confirmed by analyzing the distribution of the superabsorbent polymer particles from the X-ray image of the absorbent core.

Since the third average density of the surface layer region <NUM> is lower than the second average density, the bodily fluid that has passed to the groove portion <NUM> is transported in the lengthwise direction L of the absorbent core 9B through the main groove portion <NUM>, infiltrated into the surface layer region <NUM> in which the average density of the superabsorbent polymer particles is lower, and thus more rapidly permeates into the base potion 20B. That is, the bodily fluid more rapidly permeates from the main groove side surface <NUM> to the wide portion <NUM>, and from the sub-groove side surface <NUM> to the narrow portion <NUM>. Therefore, the absorbent article <NUM> can rapidly absorb the bodily fluid in the groove portion <NUM>. Further, the surface layer region <NUM> in which there are few superabsorbent polymer particles is less likely to cause a phenomenon that the superabsorbent polymer particles that have absorbed water and swollen spill into the groove portion <NUM> and block the groove portion <NUM>. Therefore, the absorbent article <NUM> can maintain a rapid absorption rate even when the bodily fluid is repeatedly absorbed.

Since the fourth average density of the central region <NUM> is higher than the second average density, the swelling of the base side surface <NUM> that is in contact with the groove portion <NUM> can be suppressed and the collapse of the groove portion <NUM> can be suppressed. Therefore, in the absorbent article <NUM>, even in a case where the bodily fluid is repeatedly absorbed, the bodily fluid can more reliably permeate from the groove portion <NUM> to the groove portion corresponding portion <NUM> and be absorbed.

Since the central region <NUM> is continuous from the end <NUM> of the first end portion <NUM> to the end <NUM> of the second end portion <NUM> of the absorbent core 9B, the swelling of the base side surface <NUM> that is in contact with the groove portion <NUM> can be suppressed across the entire region of the absorbent core 9B in the lengthwise direction L. Therefore, in the absorbent article <NUM>, the collapse of the groove portion <NUM> can be suppressed, and the bodily fluid can be continuously and repeatedly diffused in the lengthwise direction L.

The present invention is not limited to the above-described embodiments and these can be appropriately combined, modified, or the like without departing from the scope of the present invention.

In a case of manufacturing the absorbent article <NUM> having the configuration described in the above embodiment, there is no limitation on the manufacturing method. However, for example, the following method can be used. Incidentally, in the present specification, the "the machine direction of a material or a product" is referred to as "the MD direction", "the direction orthogonal to the MD direction on a horizontal plane" (that is, the width direction of the manufacturing line) is referred to as "the CD direction", and "the direction orthogonal to the MD direction and the CD direction" (that is, the vertical direction of the manufacturing line) is referred to as "the TD direction".

<FIG> is a schematic view showing a configuration example of a manufacturing apparatus <NUM> for manufacturing the absorbent article <NUM> according to the embodiment. In addition, <FIG> are schematic views showing a state in which the absorbent material is supplied on a suction drum <NUM> of the manufacturing apparatus <NUM> in <FIG>.

The manufacturing apparatus <NUM> includes a transport duct <NUM> and a suction drum <NUM>. The transport duct <NUM> transports the absorbent material that includes an opened water-absorbent fibers 8a and superabsorbent polymer particles 8b to the suction drum <NUM>. The transport duct <NUM> includes a transport duct nozzle <NUM> that discharges the superabsorbent polymer particles 8b from a discharge port 51Sp to the suction drum <NUM>. The suction drum <NUM> is rotatable, and sucks the absorbent material in the transport duct <NUM> and overlays the absorbent material on a plurality of concave mold members <NUM> arranged with a certain space along the circumferential direction of the outer circumferential surface to form a first laminated body <NUM> which becomes the absorbent core 9A of the absorbent body 7A in the later process.

The manufacturing apparatus <NUM> further includes an unwinding roll <NUM> for a core wrap continuous body. The unwinding roll <NUM> unwinds a long core wrap continuous bodies <NUM> toward the suction drum <NUM>. The suction drum <NUM> places the first laminated body <NUM> on the outer circumferential surface of the suction drum on the core wrap continuous body <NUM>. The first laminated body <NUM> placed on the core wrap continuous body <NUM> is covered with the core wrap continuous body <NUM> to form a second laminated body <NUM>. The manufacturing apparatus <NUM> further includes a pressing device <NUM>. The pressing device <NUM> includes a pair of press rolls 55a and 55b that apply pressure and compress the second laminated body <NUM> in the thickness direction (TD direction). A third laminated body <NUM> is formed by pressing the second laminated body <NUM>. The manufacturing apparatus <NUM> further includes an unwinding roll <NUM> for a liquid-permeable sheet continuous body. The unwinding roll <NUM> unwinds and laminates a long liquid-permeable sheet continuous body <NUM> that serves as the liquid-permeable sheet <NUM> on one surface (in the case of <FIG>, the upper surface) of the third laminated body <NUM>. The liquid-permeable-sheet continuous body <NUM> is laminated on the third laminated body <NUM> to form a fourth laminated body <NUM>. The manufacturing apparatus <NUM> further includes an unwinding roll <NUM> for a liquid-impermeable sheet continuous body. The unwinding roll <NUM> unwinds and joins a long liquid-impermeable sheet continuous body <NUM> that serves as the liquid-impermeable sheet <NUM> to the surface (in the case of <FIG>, the lower surface) of the fourth laminated body <NUM> opposite to the liquid-permeable sheet continuous body <NUM>. The liquid-impermeable sheet continuous body <NUM> is laminated on the fourth laminated body <NUM> to form a fifth laminated body <NUM>.

It should be noted that the manufacturing apparatus <NUM> includes a device (not shown) that cuts the fifth laminated body <NUM> into the shape of the absorbent article <NUM> as a product so as to be a single absorbent article <NUM>, and each of the devices that compresses leakproof walls <NUM> and the tape fasteners <NUM> onto the fifth laminated body <NUM> on the downstream side in the MD direction with respect to the unwinding roll <NUM>. However, since these devices are ordinary devices known in this technical field, the detailed explanation is omitted.

In a case where the absorbent article <NUM> is manufactured by using the manufacturing apparatus <NUM> described above, the following steps are performed. That is, the following steps are sequentially performed: a first step of forming the first laminated body <NUM>; a second step of covering the first laminated body <NUM> with the core wrap continuous body <NUM> to form the second laminated body <NUM>; and a third step of compressing the second laminated body <NUM> in the TD direction with the pressing device <NUM> to form the third laminated body <NUM>. Further, a fourth step of overlaying the liquid-permeable sheet continuous body <NUM> on the third laminated body <NUM> to form the fourth laminated body <NUM>, and a fifth step of joining the liquid-impermeable sheet continuous body <NUM> to the fourth laminated body <NUM> to form the fifth laminated body <NUM> are sequentially performed.

First, the first step of forming the first laminated body <NUM> that will ultimately constitute the absorbent core 9A of the absorbent body 7A is performed. In the first step, the absorbent material which includes the water-absorbent fibers 8a and the superabsorbent polymer particles 8b is sucked by the suction drum <NUM> through the transport duct <NUM>, and the absorbent material is laminated in the mold member <NUM> on the outer circumferential surface of the suction drum <NUM> to form the first laminated body <NUM>.

Here, the mold member <NUM> includes four pairs of protruding portions (in <FIG>, only 53a and 53b are shown) having a quadrangular cross section which extend in the circumferential direction of the suction drum <NUM> in a bottom portion 53c. Specifically, each of the protruding portions 53a and 53b has a rectangular shape. These protruding portions 53a and 53b are arranged at positions adapted to the positions of the groove portions <NUM> of the absorbent body 7A so as to have the shape and the width in the lengthwise direction adapted to the shape and the width in the lengthwise direction of the groove portions <NUM>.

<FIG> shows a state in which the absorbent material is supplied on the suction drum <NUM> in the first region (for example, the first <NUM>/<NUM> of the entire region) and in an intermediate region (for example, <NUM>/<NUM> of the middle area of the entire region) of the region in which the absorbent material is supplied in the transport duct <NUM>. This region is a region controlled so that the superabsorbent polymer particles 8b discharged from the discharge port 51Sp are supplied by a predetermined amount and the water-absorbent fibers 8a are supplied by a predetermined amount. Therefore, the superabsorbent polymer particles 8b and the water-absorbent fibers 8a are supplied and overlaid on each other. The total laminate thickness of the superabsorbent polymer particles 8b and the water-absorbent fibers 8a is the same as the height of the protruding portions 53a and 53b. In this manner, the skin side layer 6A is formed.

<FIG> shows a state in which the absorbent material is supplied on the suction drum <NUM> in the last region (for example, the last <NUM>/<NUM> of the entire region) of the region in which the absorbent material is supplied in the transport duct <NUM>. This region is a region controlled so that the superabsorbent polymer particles 8b discharged from the discharge port 51Sp are supplied by a small amount (less than the "predetermined amount" of (a)) or almost no amount of the superabsorbent polymer particles are supplied and the water-absorbent fibers 8a are supplied by a predetermined amount. Therefore, mainly the water-absorbent fibers 8a are supplied and overlaid on each other. The total laminate thickness of the superabsorbent polymer particles 8b and the water-absorbent fibers 8a is larger than the height of the protruding portions 53a and 53b. Therefore, the non-skin side layer <NUM> is further formed. The absorbent core 9A according to the first embodiment can be finally obtained by removing the absorbent core 9A from the suction drum <NUM> and turning the absorbent core upside down in the drawing.

In a case of forming the base potion 20B having the surface layer region <NUM> and the central region <NUM> according to the second embodiment, before the state of <FIG>, the superabsorbent polymer particles 8b discharged from the discharge port 51Sp are supplied by a small amount (less than the "predetermined amount of (a)) or almost no amount of the superabsorbent polymer particles are supplied and the water-absorbent fibers 8a are supplied by a predetermined amount. Then, the surface layer region <NUM> can be formed on the top surface <NUM> side. Thereafter, when the superabsorbent polymer particles 8b and the water-absorbent fibers 8a are overlaid in the order of <FIG>, the absorbent material is supplied from the transport duct nozzle (not shown) that discharges the superabsorbent polymer particles 8b in a relatively large amount. In this case, since the superabsorbent polymer particles 8b are contained in a high discharge amount, when the superabsorbent polymer particles 8b collide with the protruding portions 53a and 53b, the superabsorbent polymer particles 8b easily rebound, and the surface layer region <NUM> having a low average density of the superabsorbent polymer particles 8b is formed in the vicinity of the protruding portions 53a and 53b. At the same time, the protruding portions 53a and 53b of the superabsorbent polymer particles are collected at the center, and the central region <NUM> in which the average density of the superabsorbent polymer particles is high is formed at the center. As described above, the base potion 20B having the surface layer region <NUM> and the central region <NUM> is formed, and thus the absorbent core 9B according to the second embodiment can be obtained.

In the second step, the rotated suction drum <NUM> transfers the first laminated body <NUM> in the mold member <NUM> onto the core wrap continuous body <NUM> (coated with an adhesive) that is unwound from the unwinding roll <NUM> for the core wrap continuous body and is moved in the MD direction. Then, the core wrap continuous body <NUM> is folded along the outer circumferential surface of the first laminated body <NUM> in the CD direction orthogonal to the MD direction with folding means (not shown), and the core wrap continuous body <NUM> is covered with the first laminated body <NUM> by being wound to form the long second laminated body <NUM>. Next, in the third step, the second laminated body <NUM> is passed between the pair of press rolls 55a and 55b of the pressing device <NUM> to compress the second laminated body <NUM> in the TD direction. At this time, the third laminated body <NUM> is formed. Next, in the fourth step, the liquid-permeable continuous body <NUM> which is unwound from the unwinding roll <NUM> for the liquid-permeable continuous body is laminated on the upper surface of the third laminated body <NUM> with an adhesive agent such as a hot-melt adhesive agent to form the long fourth laminated body <NUM>. Next, in the fifth step, the liquid-impermeable sheet continuous body <NUM> which is unwound from the unwinding roll <NUM> for the liquid-impermeable sheet continuous body is joined to the lower surface of the fourth laminated body <NUM> with an adhesive such as a hot-melt adhesive to form the long fifth laminated body <NUM>. After the fifth step is completed, the fifth laminated body <NUM> is cut into the shape of the absorbent article <NUM> by a cutting device. Due to that, the absorbent article <NUM> is completed. Each step can be appropriately changed without departing from the spirit of the present disclosure.

Hereinafter, the present invention will be described by showing examples, but the present invention is not limited to these examples.

An absorbent core having a size of <NUM> × <NUM> (lengthwise direction × lateral direction) and containing pulp fibers and superabsorbent polymer particles (SAP) as water-absorbent fibers was manufactured according to the above-described manufacturing method. In the steps of <FIG>, the basis weights of the pulp fibers and the superabsorbent polymer particles were appropriately adjusted. The lateral length of the main groove portion was <NUM>, the lateral length of the sub-groove portion was <NUM>, and the lengthwise length of the sub-groove portion was <NUM>.

Next, as for the absorbent core, hydrophilic polypropylene spunbond (PPSB, basis weight: <NUM>/m<NUM>, <NUM> × <NUM>) was used as a core wrap of the skin side layer, and hydrophilic polypropylene spunbond (PPSB, basis weight: <NUM>/m<NUM>, <NUM> × <NUM>) was used as a core wrap on the non-skin layer side with a hot-melt adhesive interposed therebetween. The skin side layer and the non-skin side layer were covered with two core wraps, a side crossing the non-skin side layer in the lateral direction was wound toward the skin side layer to be attached to the surface of the skin side layer, and thus an absorbent body was formed. The thickness of the absorbent core was adjusted by pressing the absorbent body with a hydraulic press machine. Therefore, the absorbent bodies of Examples <NUM> to <NUM> were formed from the absorbent cores of Examples <NUM> to <NUM>, and the absorbent bodies of Reference Example <NUM> and Comparative Example <NUM> were formed from the absorbent cores of Reference Example <NUM> and Comparative Example <NUM>. Thereafter, a liquid-permeable sheet (air-through nonwoven fabric) was attached to the layer side on the skin side of each absorbent body, and a liquid-impermeable sheet (polyethylene film) was attached to the layer side on the non-skin side. Therefore, simple absorbent articles of Examples <NUM> to <NUM> were formed from the absorbent bodies of Examples <NUM> to <NUM>, and simple absorbent articles of Reference Example <NUM> and Comparative Example <NUM> were formed from the absorbent bodies of Reference Example <NUM> and Comparative Example <NUM>. Specific configurations of examples, reference examples, and comparative examples are as shown in Table <NUM>. In Table <NUM>, "Direction of groove portion" indicates a position where the groove portion is formed. A case where the groove portion is formed in the skin side layer is represented as "up" and a case where the groove portion is formed in the non-skin side layer is represented as "down". In Table <NUM>, "SAP composition ratio (%)" indicates the composition ratio of SAP contained in the skin side layer and the non-skin side layer with respect to SAP contained in the entire absorbent core. In Examples <NUM> to <NUM>, the groove portions are formed in the skin side layer. In Example <NUM>, the skin side layer was formed of pulp fibers and SAP, and the non-skin side layer was formed of only pulp fibers. In Examples <NUM> to <NUM>, the ratio of SAP in the non-skin side layer was adjusted in a range smaller than the ratio of SAP in the skin side layer. Reference example <NUM> is different from Example <NUM> in that the groove portions are formed in the non-skin side layer. Comparative Example <NUM> is different from Examples <NUM> to <NUM> only in that the ratios of SAP contained in the skin side layer and the non-skin side layer are the same. In Examples <NUM> to <NUM>, Reference Example <NUM>, and Comparative Example <NUM>, the pulp fibers had the basis weight shown in Table <NUM>, and the thicknesses of the skin side layer and the non-skin side layer were set to be the same.

The absorbent articles of Examples <NUM> to <NUM>, Reference Example <NUM>, and Comparative Example <NUM> were subjected to an absorbent test defined below, and the thickness change, absorption rate, and liquid return amount (rewettability) were evaluated. The results of the evaluation are shown in Tables <NUM> and <NUM>.

(<NUM>) <NUM> of artificial urine (first time) is injected from a burette at a rate of <NUM>/<NUM> sec to the position B of the absorbent body.

It should be noted that the artificial urine was prepared by dissolving <NUM> of urea, <NUM> of sodium chloride, <NUM> of magnesium sulfate, <NUM> of calcium chloride, and approximately <NUM> of a dye (blue No.<NUM>) in <NUM> of ion exchange water.

In Example <NUM> and Reference Example <NUM>, the directions of the groove portions are different from each other. That is, in Example <NUM>, the groove portions and the base portions are formed in the skin side layer of the absorbent core, and the groove portion corresponding portions and the base corresponding portions are formed in the non-skin side layer. In contrast, in Reference Example <NUM>, the groove portions and the base portions are formed in the non-skin side layer of the absorbent core, and the groove portion corresponding portions and the base corresponding portions are formed in the skin side layer. When the SAP composition ratios of both the skin side layer and the non-skin side layer are combined, in Example <NUM>, the average density of the SAP in the base portions is high, whereas in Reference Example <NUM>, the average density of the SAP in the groove portion corresponding portions and the base corresponding portions is high. From the results of Table <NUM>, it was confirmed that in all items of Example <NUM>, the thickness change after absorption of <NUM> was small compared with Reference example <NUM>, the absorption rate was excellent, and the result of the liquid return amount was equal to or less than the liquid return of Reference example <NUM>. In Example <NUM>, the groove portion corresponding portions and the base corresponding portions are arranged in a manner of continuing in the non-skin side layer, and in addition to the base corresponding portions, the groove portion corresponding portions contribute to diffusion. Further, in Example <NUM>, since the absorption rate is faster than the absorption rate of Reference Example <NUM>, it can be said that the diffusibility of the absorbent core is excellent. That is, in Example <NUM>, the bodily fluid can be diffused by transporting the bodily fluid in the lengthwise direction of the absorbent core by the groove portions formed in the skin side layer. Since the non-skin side layer has the groove portion corresponding portion in addition to the base corresponding portion, and the base corresponding portion and the groove portion corresponding portion do not contain SAP, the bodily fluid can be more reliably diffused. Further, it was found that by diffusing the bodily fluid and then absorbing the bodily fluid in the base portions, an increase in the overall thickness can be suppressed even when the bodily fluid is repeatedly absorbed, the absorption rate among the absorption performance can be enhanced, and the rewettability can be maintained.

On the other hand, in a case of Reference Example <NUM>, since the skin side layer contains a large amount of SAP, the bodily fluid is less likely to pass to the groove portions through the groove portion corresponding portions of the skin side layer. Further, in Reference Example <NUM>, there is no SAP contained in the non-skin side layer, and the base potion, substantially formed of only pulp fibers, contracts in volume due to water absorption, and also the groove portion contracts. Therefore, in Reference Example <NUM>, the thickness change was relatively small by an amount corresponding to the delay in the passage of water to the groove portions, but the thickness change was still larger than the thickness change in Example <NUM>. As for Reference Example <NUM>, a configuration in which the amount of SAP of the groove portion corresponding portion is reduced and the amounts of SAP of the base potion and the base corresponding portion are increased correspondingly can be considered as a comparative example with respect to Example <NUM>. In such a case, in the comparative example, the density of SAP in the base corresponding portion is highest, and then the average density of SAP in the groove portion corresponding portion and the base potion is similarly low. In the comparative example, the base corresponding portion absorbs a larger amount of bodily fluid than in Reference Example <NUM>, the densities of SAP of the base corresponding portion and the base potion are higher than in Reference Example <NUM>, and the volume of the groove portion is increased due to water absorption. Therefore, the thickness becomes larger than in Reference Example <NUM>. Therefore, in the configuration having the groove portions in the non-skin side layer, it can be said that the thickness is likely to become larger than the thickness in Example <NUM>.

Claim 1:
An absorbent article (<NUM>) having a lengthwise direction (L), a lateral direction (W), and a thickness direction (T), the absorbent article (<NUM>) comprising:
an absorbent core (9A) that contains superabsorbent polymer particles, wherein
the absorbent core (9A) has a skin facing surface (<NUM>), and a non-skin facing surface (<NUM>), and is formed of a skin side layer (6A) on a skin facing surface side, and a non-skin side layer (<NUM>) on a non-skin facing surface side,
the skin side layer (6A) includes
a plurality of groove portions (<NUM>) that extend in the lengthwise direction (L) and penetrate in the thickness direction (T), and
a plurality of base portions (20A) that extend in the lengthwise direction (L),
each of the plurality of groove portions (<NUM>) and each of the plurality of base portions (20A) alternately extend in the lateral direction (W),
the plurality of groove portions (<NUM>) include
a plurality of main groove portions (<NUM>) that extend in the lengthwise direction (L), and
a plurality of sub-groove portions (<NUM>) that are present in communication with each of the plurality of main groove portions (<NUM>) through base ends with predetermined spaces in a direction crossing each of the plurality of main groove portions (<NUM>),
the non-skin side layer (<NUM>) includes a plurality of groove portion corresponding portions (<NUM>) and a plurality of base corresponding portions (<NUM>) at positions that overlap the plurality of groove portions (<NUM>) and the plurality of base portions (20A) in the thickness direction (T), respectively, and
a first average density of the superabsorbent polymer particles contained in each of the plurality of groove portion corresponding portions (<NUM>) and the plurality of base corresponding portions (<NUM>) is lower than a second average density of the superabsorbent polymer particles contained in each of the plurality of base portions (20A).