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 the absorbent article, the absorbent core is formed of a first layer on a non-skin facing surface side and a second layer on a skin facing surface side. The first layer includes a plurality of groove portions including a plurality of main groove portions that extend in a longitudinal direction and penetrate the first layer in a thickness direction, and a plurality of base portions that extend in the longitudinal direction, and each of the plurality of main groove portions and each of the plurality of base portions are arranged alternately in a lateral direction. The second layer includes a plurality of main groove portion corresponding portions and a plurality of base corresponding portions arranged at positions overlapping with the plurality of main groove portions and the plurality of base portions 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.

Patent Literature <NUM>: <CIT> <CIT> discloses a further prior art example of an absorbent article including an absorbent core including superabsorbent polymer particles.

An absorbent article as described in Patent Literature <NUM> includes a main groove portion and a base portion adjacent to the main groove portion in the first layer on the non-skin facing surface side. Therefore, the bodily fluid (for example: urine) that has reached the first layer through the second layer can be diffused in the main groove portion in the longitudinal direction, can penetrate into the base portion and diffuse in the lateral direction, and thus can be held in the base 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 included in the base portion and swell by absorbing the bodily fluid, the shape of the main groove portion in the thickness direction can be maintained. Therefore, such an absorbent article has excellent absorption performance, for example, diffusibility of bodily fluid, absorption rate, and liquid return suppression, even when the absorbent article repeatedly absorbs the bodily fluid.

However, in such an absorbent article, as the number of times the absorbent article absorbs a bodily fluid increases, the degree of swelling of the superabsorbent polymer particles in the base portion becomes excessively large, and there is a risk that the swollen superabsorbent polymer particles may block the bodily fluid (blocking). In such a case, since the bodily fluid is less likely to penetrate into the base portion and diffuse into the base portion in the lateral direction, there is a risk that the bodily fluid may not be sufficiently absorbed by the absorbent core to cause the deterioration of the absorption performance of the absorbent article, for example, absorption rate, and liquid return suppression. Therefore, there is room for improvement in absorption performance in a case where a bodily fluid is repeatedly absorbed in an absorbent article, for example, absorption rate, and liquid return suppression.

An object of the present invention is to provide an absorbent article capable of improving absorption performance, for example, absorption rate, and liquid return suppression in a case where a bodily fluid is repeatedly absorbed in the absorbent article.

According to the present invention, there is provided an absorbent article as claimed in claim <NUM>. The dependent claims set out preferred but optional features.

According to the present invention, an absorbent article capable of improving absorption performance, for example, absorption rate, and liquid return suppression in a case where a bodily fluid is repeatedly absorbed in the absorbent article can be provided.

The present embodiment relates to the following aspects.

An absorbent article having a longitudinal direction, a lateral direction, and a thickness direction, the absorbent article comprising: an absorbent core including superabsorbent polymer particles, wherein the absorbent core has a non-skin facing surface, and a skin facing surface, and is formed of a first layer on a non-skin facing surface side, and a second layer on a skin facing surface side, the first layer includes: a plurality of groove portions that includes a plurality of main groove portions extending in the longitudinal direction and penetrating the first layer in the thickness direction, and a plurality of base portions that extend in the longitudinal direction, each of the plurality of main groove portions and each of the plurality of base portions are arranged alternately in the lateral direction, each of the plurality of base portions is formed of: a base inner side portion adjacent to the non-skin facing surface side of the second layer, and a base outer side portion adjacent to the non-skin facing surface side of the base inner side portion, and an average density of the superabsorbent polymer particles contained in the base outer side portion is lower than an average density of the superabsorbent polymer particles contained in the base inner side portion.

Since the absorbent article includes the predetermined main groove portions and the predetermined base portions in the first layer, the bodily fluid that has permeated through the second layer is passed through the main groove portions and diffuses in the longitudinal direction while exuding into the base portions in the lateral direction. Here, in the present absorbent article, the average density of the superabsorbent polymer particles contained in the base outer side portion in the base portion of the first layer is lower than the average density of the superabsorbent polymer particles contained in the base inner side portion. Therefore, even in a case where the number of times the absorbent article absorbs the bodily fluid increases and the blocking due to the swelling of the superabsorbent polymer particles in the base inner side portion is likely to occur, the occurrence of blocking due to the swelling of the superabsorbent polymer particles in the base outer side portion can be suppressed. Due to that, the difficulty of the bodily fluid penetrating into the base portion and the difficulty of the bodily fluid diffusing in the base portion in the lateral direction can be suppressed. On the other hand, the collapse of the main groove portion in the thickness direction can be suppressed due to the swelling of the superabsorbent polymer particles in the base inner side portion. Therefore, as for the entire absorbent article, while the bodily fluid can be stably diffused in the main groove portion in the longitudinal direction, the bodily fluid can be stably diffused in the lateral direction. Accordingly, the entire absorbent core can be more effectively used for absorption of the bodily fluid, and the absorption performance, for example, absorption rate, and liquid return suppression in a case where the bodily fluid is repeatedly absorbed in the absorbent article can be enhanced.

The second layer includes: a plurality of main groove portion corresponding portions and a plurality of base corresponding portions arranged at positions overlapping with the plurality of main groove portions and the plurality of base portions in the thickness direction, respectively, and 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.

In the absorbent article, both the average density of the superabsorbent polymer particles contained in the base portion and the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion are lower than the average density of the superabsorbent polymer particles contained in the base corresponding portion. Therefore, when bodily fluid is absorbed, the bodily fluid can easily permeate into the main groove portion through the main groove portion corresponding portion, the water flow function of the main groove portion can be secured, and the bodily fluid that cannot be held in the base portion can be easily absorbed in the base corresponding portion. As described above, in the absorbent article, the bodily fluid can be absorbed by a bodily fluid absorption cycle in which the bodily fluid permeates from the main groove portion corresponding portion to the main groove portion (also referred to as "bodily fluid permeation action"), the permeated bodily fluid is drawn from the main groove portion to the adjacent base portion (also referred to as "bodily fluid drawing action"), and when the drawn bodily fluid cannot be held in the base portion, the bodily fluid is sucked up by the base corresponding portion (also referred to as "bodily fluid sucking action"). At this time, in the absorbent article, even when blocking in the base inner side portion is likely to occur, the occurrence of blocking due to the swelling of the superabsorbent polymer particles in the base outer side portion can be suppressed, and thus the bodily fluid absorption cycle can be stably maintained. Accordingly, even in a case where the bodily fluid is repeatedly absorbed in the absorbent article, the absorption performance can be enhanced.

The absorbent article according to aspect <NUM>, wherein a thickness of the base outer side portion in the thickness direction is in a range of <NUM>% to <NUM>% of a thickness of each of the plurality of base portions in the thickness direction.

In the absorbent article, the thickness of the base outer side portion is in a range of <NUM>% to <NUM>% of the thickness of the base portion. Therefore, in a case where the absorbent article repeatedly absorbs bodily fluid, even when the blocking due to the swelling of the superabsorbent polymer particles in the base inner side portion is likely to occur, the occurrence of blocking due to the swelling of the superabsorbent polymer particles in the base outer side portion can be further suppressed. Therefore, the difficulty of the bodily fluid penetrating into the base portion and the difficulty of the bodily fluid diffusing in the base portion in the lateral direction can be more stably suppressed.

The absorbent article according to aspect <NUM> or <NUM>, wherein the average density of the superabsorbent polymer particles contained in each of the plurality of main groove portion corresponding portions is lower than the average density of the superabsorbent polymer particles contained in the base inner side portion of each of the plurality of base portions.

In the absorbent article according to claim <NUM>, the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion is lower than the average density of the superabsorbent polymer particles contained in the base inner side portion of the base portion. Therefore, the swelling of the main groove portion corresponding portion can be suppressed, and the inhibition of the bodily fluid permeation action can be suppressed. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article can be enhanced.

The absorbent article according to aspect <NUM>,
wherein the average density of the superabsorbent polymer particles contained in the base outer side portion of each of the plurality of base portions is lower than the average density of the superabsorbent polymer particles contained in each of the plurality of main groove portion corresponding portions.

In the absorbent article, the average density of the superabsorbent polymer particles contained in the base outer side portion of the base portion is lower than the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion. Therefore, the swelling of the base outer side portion can be suppressed, and the inhibition of the bodily fluid drawing action can be suppressed. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article can be enhanced.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein each of the plurality of groove portions further includes sub-groove portions that penetrate the first layer in the thickness direction and are present in communication with each of the plurality of main groove portions through a base end with a predetermined space in a direction crossing each of the plurality of main groove portions.

In the absorbent article, since the groove portion further includes a sub-groove portion crossing the main groove portion, the diffusion of the bodily fluid in the groove portion can be rapidly performed. Therefore, the entire absorbent core can be more effectively used for absorption of the bodily fluid, and thus the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article can be enhanced.

The absorbent article according to aspect <NUM>, wherein the second layer further includes: sub-groove portion corresponding portions arranged at positions overlapping with the sub-groove portions in the thickness direction, and an average density of the superabsorbent polymer particles contained in the sub-groove portion corresponding portion is lower than an average density of the superabsorbent polymer particles contained in each of the plurality of base corresponding portions. In the absorbent article, the average density of the superabsorbent polymer particles contained in the sub-groove portion corresponding portion is lower than the average density of the superabsorbent polymer particles contained in each of the base corresponding portions. Therefore, when bodily fluid is absorbed, the bodily fluid can easily permeate into the sub-groove portion through the sub-groove portion corresponding portion, and the water flow function of the sub-groove portion can be secured. In addition, the bodily fluid can be further absorbed by a bodily fluid absorption cycle in which while being diffused in a direction crossing the longitudinal direction along the sub-groove portion, the bodily fluid is drawn into the base portion and held therein, and the bodily fluid that cannot be held in the base portion is sucked up to the base corresponding portion. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article can be enhanced.

The absorbent article according to any one of aspects <NUM> to <NUM>, wherein in each of the plurality of base portions, at one end portion and the other end portion in the lateral direction, and at a central part between the one end portion and the other end portion, an average density of the superabsorbent polymer particles contained in each of the one end portion and the other end portion is lower than an average density of the superabsorbent polymer particles contained in the central part.

In the absorbent article, in the lateral direction, the average density of the superabsorbent polymer particles contained in both end portions of the base portion is lower than the average density of the superabsorbent polymer particles contained in the central part. Therefore, the swelling of both end portions that come into contact with the main groove portion in the base portion can be suppressed, and the inhibition of the bodily fluid drawing action can be suppressed. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article can be enhanced.

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.

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 two 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.

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

<FIG> are views showing configuration examples of an absorbent article <NUM> according to the embodiment, specifically, a disposable diaper. Specifically, <FIG> is a plan view showing a configuration example of the absorbent article <NUM> according to the embodiment. <FIG> is a plan view showing a configuration example of an absorbent body <NUM> of the absorbent article <NUM> according to the embodiment. <FIG> is a plan view showing a configuration example of an absorbent core <NUM> of the absorbent article <NUM> according to the embodiment. <FIG> are a cross-sectional view taken along a line IV-IV in <FIG>, and a cross-sectional view taken along a line V-V, respectively.

<FIG> is a schematic view showing the flow of bodily fluid in the cross section taken along the line IV-IV in <FIG>.

As shown in <FIG>, the absorbent article <NUM> includes a liquid-permeable sheet <NUM>, a liquid-impermeable sheet <NUM>, and an absorbent body <NUM> arranged between the liquid-permeable sheet <NUM> and the liquid-impermeable sheet <NUM>. As shown in <FIG> and <FIG>, the absorbent body <NUM> has a longitudinal direction L, a lateral direction W, and a thickness direction T, and includes an absorbent core <NUM> having a skin facing surface <NUM> and a non-skin facing surface <NUM>. In the present embodiment, the absorbent core <NUM> includes 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 longitudinal direction, the lateral direction, and the thickness direction of the absorbent article <NUM> are the same as those of the absorbent body <NUM>, the longitudinal direction L, the lateral direction W, and the thickness direction T are used as the directions of the absorbent article <NUM>.

In the present embodiment, as shown in <FIG>, the absorbent article <NUM> further includes a pair of leakproof walls <NUM> including elastic members <NUM>, fixed portions <NUM> that fixe the leakproof walls <NUM> to the liquid-permeable sheet <NUM>, an elastic members <NUM> around the leg portions, a tape fasteners <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 core <NUM> has the non-skin facing surface <NUM> and the skin facing surface <NUM>, and is formed of a first layer <NUM> on the non-skin facing surface side and a second layer <NUM> on the skin facing surface side. In addition, the first layer <NUM> includes a plurality of groove portions <NUM> including a plurality of main groove portions <NUM> that linearly extend in the longitudinal direction L and penetrate the first layer in the thickness direction T, and a plurality of base portions <NUM> that extend in the longitudinal direction L, and each of the plurality of main groove portions <NUM> and each of the plurality of base portions <NUM> are arranged alternately in the lateral direction W. The main groove portion <NUM> is recessed from the non-skin facing surface <NUM> toward the skin facing surface <NUM> in the thickness direction of the absorbent core <NUM> and extends in the longitudinal direction L. The base portion <NUM> is formed of a base inner side portion <NUM> adjacent to the non-skin facing surface <NUM> side of the second layer <NUM>, and a base outer side portion <NUM> adjacent to the non-skin facing surface <NUM> side of the base inner side portion <NUM>.

In the present embodiment, the second layer <NUM> includes a plurality of main groove portion corresponding portions <NUM> at positions that overlap with the plurality of main groove portions <NUM> in the thickness direction T, and a plurality of base corresponding portions <NUM> at positions that overlap with the plurality of base portions <NUM> in the thickness direction T. Further, in the present embodiment, as shown in <FIG> and <FIG>, the groove portion <NUM> includes a plurality of sub-groove portions <NUM>. In addition, the second layer <NUM> includes a plurality of sub-groove portion corresponding portions <NUM> at positions that overlap with the plurality of sub-groove portions <NUM> in the thickness direction T.

In the present embodiment, the thickness of each of the first layer <NUM> and the second layer <NUM> is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and even more preferably <NUM> to <NUM>. It should be noted that, in the present embodiment, the thickness of each of the first layer <NUM> and the second 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 <NUM> 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 non-skin facing surface <NUM> having the plurality of groove portions <NUM> and the plurality of base portions <NUM> formed thereon faces upward, the displacement from the measurement table is measured by the laser displacement meter for five different base portions <NUM>, 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 second layer <NUM> is Ay (mm), and the thickness of the first layer <NUM> is calculated from a difference between Ax (mm) and Ay (mm).

The absorbent core <NUM> 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>. In the present embodiment, the average basis weight of the absorbent fibers in both the first layer <NUM> and the second layer <NUM> is preferably <NUM> to <NUM>/m<NUM>, and more preferably <NUM> to <NUM>/m<NUM>. In addition, the average basis weight of the superabsorbent polymer particles in the first layer <NUM> is smaller than the average basis weight of the superabsorbent polymer particles in the second layer <NUM>. The average basis weight of the superabsorbent polymer particles in the first 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 second layer <NUM> is preferably <NUM> to <NUM>/m<NUM>, and more preferably <NUM> to <NUM>/m<NUM>. A ratio of the average basis weight of the superabsorbent polymer particles in the first layer <NUM> to the average basis weight of the superabsorbent polymer particles in the entire absorbent core <NUM> is preferably <NUM>% to <NUM>% and more preferably <NUM>% to <NUM>%.

As shown in <FIG>, in the absorbent core <NUM>, the base outer side portion <NUM> of the base portion <NUM> and the base inner side portion <NUM> of the base portion <NUM> each have different average densities of the superabsorbent polymer particles. Specifically, the average density of the superabsorbent polymer particles contained in the base outer side portion <NUM> is lower than the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM>. Further, in the present embodiment, the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM> is equal to the average density of the superabsorbent polymer particles contained in the second layer <NUM> or lower than the average density of the superabsorbent polymer particles contained in the second layer <NUM>.

As described above, in the present embodiment, the average densities of the superabsorbent polymer particles have a relationship of the base outer side portion <NUM> < the base inner side portion <NUM> ≤ the second layer <NUM>. In such a configuration, for example, as shown in <FIG>, in the present embodiment, the bodily fluid moves in the absorbent core <NUM> in substantially the following order.

Since the absorbent article <NUM> includes the predetermined main groove portion <NUM> and the predetermined base portion <NUM> in the first layer <NUM>, the bodily fluid that has permeated through the second layer <NUM> is passed through the main groove portion <NUM> and diffuses in the longitudinal direction L while exuding into the base portion <NUM> in the lateral direction W. Here, in the absorbent article <NUM>, the average density of the superabsorbent polymer particles contained in the base outer side portion <NUM> of the base portion <NUM> of the first layer <NUM> is lower than the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM>. Therefore, even when the number of times the absorbent article <NUM> absorbs the bodily fluid increases and the blocking due to the swelling of the superabsorbent polymer particles in the base inner side portion <NUM> is likely to occur (the arrow B2 stops), the occurrence of blocking due to the swelling of the superabsorbent polymer particles in the base outer side portion <NUM> can be suppressed. That is, regardless of the increase in the number of times of absorption of the bodily fluid, a state in which the bodily fluid moved to the main groove portion <NUM> easily continuously exudes into the base outer side portion <NUM> can be maintained (arrow B1 continues). Due to that, the difficulty of the bodily fluid penetrating into the base portion <NUM> and the difficulty of the bodily fluid diffusing in the base portion <NUM> in the lateral direction W can be suppressed. On the other hand, the collapse of the main groove portion <NUM> in the thickness direction T can be suppressed due to swelling of the superabsorbent polymer particles in the base inner side portion <NUM>. Therefore, as for the entire absorbent article <NUM>, while the bodily fluid can be stably diffused in the main groove portion <NUM> in the longitudinal direction L, the bodily fluid can be stably diffused in the lateral direction W. Accordingly, the entire absorbent core <NUM> can be more effectively used for absorption of the bodily fluid, and the absorption performance, for example, absorption rate, and liquid return suppression in a case where the bodily fluid is repeatedly absorbed in the absorbent article <NUM> can be enhanced.

In the present embodiment, the average density of the superabsorbent polymer particles contained in the base outer side portion <NUM> is preferably <NUM> to <NUM>/cm<NUM>, more preferably <NUM> to <NUM>/cm<NUM>, and even more preferably <NUM> to <NUM>/cm<NUM>. In a case where the average density of the superabsorbent polymer particles contained in the base outer side portion <NUM> is excessively high, the blocking due to the swelling of the superabsorbent polymer particles in the base outer side portion <NUM> easily occurs, and the effect that the base outer side portion <NUM> is less likely to be blocked than the base inner side portion <NUM> is less likely to be exerted.

On the other hand, the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM> is preferably <NUM> to <NUM>/cm<NUM>, more preferably <NUM> to <NUM>/cm<NUM>, and even more preferably <NUM> to <NUM>/cm<NUM>. In a case where the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM> is excessively low, the superabsorbent polymer particles in the base inner side portion <NUM> are less likely to swell, and the main groove portion <NUM> easily collapses in the thickness direction T. In a case where the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM> is excessively high, the blocking due to the swelling of the superabsorbent polymer particles in the base inner side portion <NUM> easily occur, and the diffusion of the bodily fluid in the lateral direction W is easily reduced.

At this time, a difference between the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM> and the average density of the superabsorbent polymer particles contained in the base outer side portion <NUM> is preferably <NUM> to <NUM>/cm<NUM>, more preferably <NUM> to <NUM>/cm<NUM>, and even more preferably <NUM> to <NUM>/cm<NUM>. When the difference is excessively small, blocking easily occurs in the entire base portion <NUM> (in a case where the average density is high), or the main groove portion <NUM> easily collapses in the thickness direction T (in a case where the average density is low). When the difference is excessively large, the blocking due to the swelling of the superabsorbent polymer particles in the base inner side portion <NUM> easily occurs.

Further, the average density of the superabsorbent polymer particles contained in the second layer <NUM> is preferably <NUM> to <NUM>/cm<NUM>, more preferably <NUM> to <NUM>/cm<NUM>, and even more preferably <NUM> to <NUM>/cm<NUM>. In a case where the average density of the superabsorbent polymer particles contained in the second layer <NUM> is excessively low, the absorption amount of the bodily fluid in the entire absorbent body <NUM> is easily decreased. In a case where the average density of the superabsorbent polymer particles contained in the second layer <NUM> is excessively high, the blocking due to the swelling of the superabsorbent polymer particles in the second layer <NUM> easily occurs, and the absorption amount of the bodily fluid in the base portion <NUM> is easily decreased. It should be noted that, in the present embodiment, in the second layer <NUM>, the average densities of the superabsorbent polymer particles in the main groove portion corresponding portion <NUM>, the base corresponding portion <NUM>, and the sub-groove portion corresponding portion <NUM> are substantially the same.

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 <NUM> (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 portion <NUM> (base outer side portion <NUM>, base inner side portion <NUM>) and the second layer <NUM> (main groove portion corresponding portion <NUM>, base corresponding portion <NUM>) in the absorbent core <NUM>, 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 portion <NUM>, 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 portion <NUM> and the base corresponding portion <NUM>, which will be described later, 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.

In the present embodiment, the thickness of the base outer side portion <NUM> in the thickness direction T is preferably in a range of <NUM>% to <NUM>% of the thickness of each of the plurality of base portions <NUM> in the thickness direction T, more preferably in a range of <NUM>% to <NUM>%, and even more preferably in a range of <NUM>% to <NUM>%. However, the thickness of the base portion <NUM> in the thickness direction T can be referred to as the thickness of the first layer <NUM> (base inner side portion <NUM> + base outer side portion <NUM>) or the groove depth of the main groove portion <NUM>.

In such an absorbent article <NUM>, the thickness of the base outer side portion <NUM> is in a range of <NUM>% to <NUM>% of the thickness of the base portion. Therefore, even in a case where the blocking due to the swelling of the superabsorbent polymer particles in the base inner side portion <NUM> is likely to occur when the absorbent article <NUM> repeatedly absorbs the bodily fluid, the occurrence of the blocking due to the swelling of the superabsorbent polymer particles of the base outer side portion <NUM> can be further suppressed. That is, even when the bodily fluid is less likely to penetrate into the base portion <NUM> through the base inner side portion <NUM>, the bodily fluid can be allowed to penetrate into the base portion <NUM> through the base outer side portion <NUM>. Therefore, the difficulty of the bodily fluid penetrating into the base portion <NUM> and the difficulty of the bodily fluid diffusing in the base portion <NUM> in the lateral direction W can be more stably suppressed.

It should be noted that, in a case where a ratio of the thickness of the base inner side portion <NUM> to the thickness of the base portion <NUM> is excessively low, the amount of the superabsorbent polymer particles that swell in the base inner side portion <NUM> is decreased, and the main groove portion <NUM> easily collapses in the thickness direction T. On the other hand, in a case where the ratio of the thickness of the base inner side portion <NUM> to the thickness of the base portion <NUM> is excessively high, when the bodily fluid is less likely to penetrate into the base portion <NUM> through the base inner side portion <NUM> due to the swelling of the superabsorbent polymer particles, the bodily fluid that penetrates into the base portion <NUM> through the base outer side portion <NUM> is reduced, and the absorption amount of the bodily fluid is easily reduced in the base portion <NUM>.

In the present specification, a method of measuring and calculating the relative thicknesses of the base outer side portion <NUM> and the base inner side portion <NUM> is as follows.

A sample piece including a measurement target portion is prepared from the absorbent article <NUM>. The sample piece is an absorbent body <NUM> that includes the absorbent core <NUM> and the core wrap <NUM> and from which the elastic member, the liquid-permeable sheet <NUM>, the liquid-impermeable sheet <NUM>, and the like of the absorbent article <NUM> are removed, and is a test piece for X-ray cross section observation obtained by cutting the absorbent body <NUM> in the lateral direction to have a width of <NUM> in a plan view. It should be noted that in a case where the absorbent body <NUM>, the liquid-permeable sheet <NUM>, and the liquid-impermeable sheet <NUM> are integrally formed, and in a case where the liquid-permeable sheet <NUM> and the liquid-impermeable sheet <NUM> cannot be removed without destroying the shape of the absorbent body <NUM>, the sample piece is a test piece for X-ray cross section observation having the absorbent body <NUM> that includes the absorbent core <NUM> and the core wrap <NUM>, the liquid-permeable sheet <NUM>, and the liquid-impermeable sheet <NUM> of the absorbent article <NUM> from which the elastic member is removed, and obtained by cutting the absorbent body <NUM> in the lateral direction to a width of <NUM> in a plan view. Next, by using the following X-ray photographing apparatus and image processing software, a cross section of the sample piece is photographed to obtain an internal cross-sectional photograph including the thickness direction T thereof in BMP format. Then, the obtained X-ray fluoroscopic image having a field size of <NUM> × <NUM> is tiled in the lateral direction of the absorbent body <NUM>, and the thickness of the absorbent body <NUM>, the thickness of the base outer side portion <NUM>, and the groove depth of the main groove portion <NUM> are calculated using the number of pixels of the composite image analysis software. Thereafter, assuming that the total thickness of the absorbent body <NUM> is <NUM>, the ratio of the groove depth of the main groove portion <NUM> and the thickness of the base outer side portion <NUM> is calculated. Measurement and photographing apparatus: X-ray fluoroscopy apparatus: FLEX-M863 (manufactured by Beam Sense Co.

From the internal cross-sectional photograph of the BMP format obtained in (<NUM>), the number of pixels corresponding to the total thickness of the absorbent body <NUM>, the thickness of the base outer side portion <NUM>, and the groove depth of the main groove portion <NUM> are read. The total thickness of the absorbent body <NUM>, the groove depth of the main groove portion <NUM>, the thickness of the base outer side portion <NUM>, the thickness of the base inner side portion <NUM> (the groove depth of the main groove portion <NUM> - the thickness of the base outer side portion <NUM>), and the thickness of the second layer <NUM> (the total thickness of the absorbent body <NUM> - the groove depth of the main groove portion <NUM>) are calculated. Thereafter, assuming that the total thickness of the absorbent body <NUM> is <NUM>, the ratios of the groove depth of the main groove portion <NUM>, the thickness of the base outer side portion <NUM>, the thickness of the base inner side portion <NUM>, and the thickness of the second layer <NUM> are calculated as the relative thickness and depth.

In a preferable aspect of the present embodiment, in the base portion <NUM>, at one end portion and the other end portion, and at the central part between the one end portion and the other end portion in the lateral direction W, the average density of the superabsorbent polymer particles contained in each of the one end portion and the other end portion is lower than the average density of the superabsorbent polymer particles contained in the central part. However, the end portion refers to a range of <NUM>/<NUM> of the length of the base portion <NUM> in the lateral direction W from the end edge of the base portion <NUM> in the lateral direction W. In such an absorbent article <NUM>, the swelling of two end portions that come into contact with the main groove portions <NUM> in the base portion can be suppressed, and the inhibition of the bodily fluid drawing action can be suppressed. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article <NUM> can be enhanced.

In the present embodiment, differences from the first embodiment will be mainly described. <FIG> are view showing configuration examples of the absorbent article <NUM> according to the embodiment, specifically, a disposable diaper. Specifically, <FIG> are a cross-sectional view taken along the line IV-IV in <FIG> and a cross-sectional view taken along the line V-V, respectively. <FIG> is a schematic view showing the flow of the bodily fluid in the cross-section taken along the line IV-IV in <FIG>.

As shown in <FIG>, the absorbent core <NUM> has different average densities of the superabsorbent polymer particles in the base outer side portion <NUM> and the base inner side portion <NUM> of the base portion <NUM>, the main groove portion corresponding portion <NUM>, and the base corresponding portion <NUM>. Specifically, the average density of the superabsorbent polymer particles contained in the base portion <NUM> (the base outer side portion <NUM> and the base inner side portion <NUM>) and the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion <NUM> are lower than the average density of the superabsorbent polymer particles contained in the base corresponding portion <NUM>.

In the present embodiment, the average densities of the superabsorbent polymer particles contained in the base outer side portion <NUM> and the base inner side portion <NUM> of the base portion <NUM> are as described in the first embodiment. The average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion <NUM> are preferably <NUM> to <NUM>/cm<NUM>, more preferably <NUM> to <NUM>/cm<NUM>, and even more preferably <NUM> to <NUM>/cm<NUM>. On the other hand, the average density of the superabsorbent polymer particles contained in the base corresponding portion <NUM> is preferably <NUM> to <NUM>/cm<NUM>, more preferably <NUM> to <NUM>/cm<NUM>, and even more preferably <NUM> to <NUM>/cm<NUM>.

As described above, in the present embodiment, the average densities of the superabsorbent polymer particles have a relationship of the base portion <NUM> (base outer side portion <NUM> and base inner side portion <NUM>) and the main groove portion corresponding portion <NUM> < the base corresponding portion <NUM>. In such a configuration, in the present embodiment, as shown in <FIG>, the bodily fluid moves in the absorbent core <NUM> in substantially the following order.

In the absorbent article <NUM>, both the average density of the superabsorbent polymer particles contained in the base portion <NUM> and the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion <NUM> are lower than the average density of the superabsorbent polymer particles contained in the base corresponding portion <NUM>. Therefore, when the bodily fluid is absorbed, the bodily fluid can easily permeate into the main groove portion <NUM> through the main groove portion corresponding portion <NUM>, the water flow function of the main groove portion <NUM> can be secured, and the bodily fluid that cannot be held in the base portion <NUM> can be easily absorbed in the base corresponding portion <NUM>. As described above, in the absorbent article <NUM>, the bodily fluid can be absorbed by a bodily fluid absorption cycle in which the bodily fluid permeates from the main groove portion corresponding portion <NUM> to the main groove portion <NUM> (also referred to as "bodily fluid permeation action"), the permeated bodily fluid is drawn from the main groove portion <NUM> to the adjacent base portion <NUM> (also referred to as "bodily fluid drawing action"), and when the drawn bodily fluid cannot be held in the base portion <NUM>, the bodily fluid is sucked up by the base corresponding portion <NUM> (also referred to as "bodily fluid sucking action"). At this time, in the absorbent article <NUM>, even when blocking in the base inner side portion <NUM> is likely to occur, the occurrence of blocking due to the swelling of the superabsorbent polymer particles in the base outer side portion <NUM> can be suppressed, and thus the bodily fluid absorption cycle can be stably maintained. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the present absorbent article <NUM> can be enhanced.

In a preferable aspect of the present embodiment, the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion <NUM> is lower than the average density of the superabsorbent polymer particles contained in the base inner side portion <NUM> of the base portion <NUM>. In such an absorbent article <NUM>, the swelling of the main groove portion corresponding portion <NUM> can be suppressed, and the inhibition of the bodily fluid permeation action can be suppressed. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article <NUM> can be enhanced.

In a preferable aspect of the present embodiment, the average density of the superabsorbent polymer particles contained in the base outer side portion <NUM> of the base portion <NUM> is lower than the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion <NUM>. In such an absorbent article <NUM>, the swelling of the base outer side portion <NUM> can be suppressed and the inhibition of the bodily fluid drawing action can be suppressed. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article <NUM> can be enhanced.

In a preferable aspect of the present embodiment, the average density of the superabsorbent polymer particles contained in the sub-groove portion corresponding portion <NUM> is lower than the average density of the superabsorbent polymer particles contained in the base corresponding portion <NUM>. At this time, the average density of the superabsorbent polymer particles contained in the sub-groove portion corresponding portion <NUM> is approximately the same as the average density of the superabsorbent polymer particles contained in the main groove portion corresponding portion <NUM>. In such an absorbent article <NUM>, when the bodily fluid is absorbed, the bodily fluid can easily permeate into the sub-groove portion <NUM> through the sub-groove portion corresponding portion <NUM>, and the water flow function of the sub-groove portion <NUM> can be secured. In addition, the bodily fluid can be further absorbed by a bodily fluid absorption cycle in which while being diffused in a direction crossing the longitudinal direction L along the sub-groove portion <NUM>, the bodily fluid is drawn into the base portion <NUM> (base outer side portion <NUM>, base inner side portion <NUM>) and held therein, and the bodily fluid that cannot be held in the base portion <NUM> is sucked up to the base corresponding portion <NUM>. Therefore, the absorption performance in a case where the bodily fluid is repeatedly absorbed in the absorbent article <NUM> can be enhanced.

In a preferable aspect of the first and second embodiments, as shown in <FIG>, the absorbent body <NUM> is partitioned into a right region RA and a left region LA by a longitudinal central axis line VL that bisects the absorbent body <NUM> in the lateral direction W. Further, the absorbent body <NUM> includes two main groove portions <NUM> in each of the right region RA and the left region LA.

In the first and second embodiment, as shown in <FIG>, the absorbent article <NUM> is partitioned in the longitudinal direction L 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. Further, the absorbent body <NUM> is arranged across the three regions, and the sub-groove portions <NUM> are provided in all of the three regions.

In the first and second embodiments, the groove portion <NUM> is not limited to the configuration in which the main groove portion <NUM> linearly extends along the longitudinal direction L and the sub-groove portion <NUM> is orthogonal to the main groove portion <NUM>. For example, the groove portion <NUM> may include only the main groove portion <NUM> and may not include the sub-groove portion <NUM>. Further, the main groove portion <NUM> may not extend across the front waist region FW, the crotch region C, and the back waist region RW in the longitudinal direction L of the absorbent core <NUM>, and may be arranged only in the region of the crotch region C, for example. Further, each of the plurality of main groove portions <NUM> may be arranged so as to extend in a zigzag shape along the longitudinal direction L in a plan view, and to alternately form a broad base portion having a relatively large width and a narrow base portion having a relatively narrow width with the main groove portions <NUM> which are adjacent to each other in the longitudinal direction L. Alternatively, each of the plurality of main groove portions may extend in a zigzag shape along the longitudinal direction L in a plan view, and the adjacent main groove portions <NUM> may be arranged in a manner such that the width of the base portion <NUM> becomes constant, or each of the plurality of main groove portions <NUM> may extend in a wavy shape in a plan view.

In the first and second embodiments, as shown in <FIG>, the core wrap <NUM> that covers the non-skin facing surface <NUM> of the absorbent core <NUM> may be arranged so as to protrude toward the skin facing surface <NUM> side although not to come into contact with the main groove portion corresponding portion <NUM> in the main groove portion <NUM>. In such a case, the diffusibility of the bodily fluid in the longitudinal direction L and the lateral direction W in the main groove portion <NUM> can be enhanced. Alternatively, the core wrap <NUM> that covers the non-skin facing surface <NUM> of the absorbent core <NUM> may come into contact with the main groove portion corresponding portion <NUM>, or may be partially or continuously joined to the main groove portion corresponding portion <NUM> with a compressed portion or a joining portion. As described above, the main groove portion <NUM> is formed by intermittently compressing or joining a part of the width of the main groove portion corresponding portion <NUM> along the main groove portion <NUM>, and thus the wearer is less likely to feel the hardness of the compressed portion or the joining portion. In addition, since the main groove portion <NUM> is formed by continuously compressing or joining a part of the width of the main groove portion corresponding portion <NUM> in the longitudinal direction L, the absorbent article <NUM> is easily folded with respect to the main groove portion <NUM>, and exhibits excellent fitting property.

In the first and second embodiment, in the absorbent article <NUM>, the main groove portion <NUM> has a width of 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 <NUM>. 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 <NUM> seconds after being applied with pressure is measured, and the average value of the <NUM> measurement values is used as the thickness of the object.

In the first and second embodiments, a space between the sub-groove portions <NUM> that are adjacent to each other in the lateral direction W is preferably <NUM>% to <NUM>%, and more preferably <NUM>% to <NUM>% of the space between the plurality of main groove portions <NUM> that are adjacent to each other in the lateral direction W. As described above, when the sub-groove portions <NUM> have a predetermined space, a predetermined width can be secured in the base portion <NUM> present between the sub-groove portions <NUM>, the bodily fluid absorbed in the base portion <NUM> through the sub-groove portions <NUM> is easily diffused in the longitudinal direction L, and even when the bodily fluid is repeatedly absorbed, the absorbent article <NUM> has excellent diffusibility, absorption rate, and liquid return suppression.

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> of manufacturing the absorbent article <NUM> according to the embodiment. In addition, <FIG> are schematic views showing the 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 laminates 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 <NUM> of the absorbent body <NUM> in the later process.

The manufacturing apparatus <NUM> further includes an unwinding roll <NUM> for the 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 laminating 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 <NUM> of the absorbent body <NUM> 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 main groove portions <NUM> of the absorbent body <NUM> so as to have the shape and the width in the longitudinal direction adapted to the shape and the width in the longitudinal direction of the main groove portions <NUM>.

<FIG> shows the 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) 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 or almost no amount of the superabsorbent polymer particles is supplied and the water-absorbent fibers 8a are supplied by a predetermined amount. Therefore, the water-absorbent fibers 8a are mainly supplied to and laminated on the bottom portion 53c of the mold member <NUM> of the suction drum <NUM>. The total laminated thickness of the superabsorbent polymer particles 8b and the water-absorbent fibers 8a is smaller than the height of the protruding portions 53a and 53b. As a result, portions corresponding to the base outer side portions <NUM> are formed.

<FIG> shows the state in which the absorbent material is supplied on the suction drum <NUM> 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 another predetermined amount (more than the "small amount" of (a)) 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 laminated on the upper part of the bottom portions 53c and the protruding portions 53a and 53b of the mold member <NUM> on the outer circumferential surface of the suction drum <NUM>. 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. Accordingly, portions corresponding to the base inner side portions <NUM> and a part of the second layer <NUM> are further formed.

<FIG> shows the 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 of the superabsorbent polymer particles 8b discharged from the discharge port 51Sp are supplied by small amount or another 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 laminated on the upper part of the bottom portions 53c and the protruding portions 53a and 53b of the mold member <NUM> of the suction drum <NUM>. 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. As a result, the remainder of the second layer <NUM> is further formed, and finally the absorbent core <NUM> is formed.

It should be noted that, in a case where it is desired to decrease the average density of the superabsorbent polymer particles in the main groove portion corresponding portion <NUM> (or the sub-groove portion corresponding portion <NUM>) of the second layer <NUM> in the second embodiment, the manufacturing method of Patent Literature <NUM> (<CIT>) can be applied. For example, when a transport duct nozzle <NUM> that discharges the superabsorbent polymer particles 8b in a relatively large amount is further arranged in the transport duct <NUM> and the second layer <NUM> is formed, the absorbent material is supplied from the transport duct nozzle <NUM> present at a lower position than the transport duct nozzle <NUM>. In such a case, since the superabsorbent polymer particles 8b are contained in a large discharge amount, when the superabsorbent polymer particles 8b collide with the protruding portions 53a and 53b, the superabsorbent polymer particles 8b are easily bounced back, and due to that, in the first laminated body <NUM>, there is a portion in which the average density of the superabsorbent polymer particles 8b is low in the portions on the protruding portions 53a and 53b. The portions on the protruding portions 53a and 53b serve as portions corresponding to the main groove portion corresponding portions <NUM> (or the sub-groove portion corresponding portions <NUM>).

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.

In the above manufacturing method, an aspect has been described in which the mold member <NUM> is provided with the protruding portions 53a and 53b for forming the main groove portion <NUM>. However, as a method of manufacturing the absorbent article, the mold member <NUM> may be provided with the protruding portions for forming the sub-groove portions <NUM>. Further, each step can be appropriately changed without departing from the scope 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 including pulp (average basis weight: <NUM>/m<NUM>) and the superabsorbent polymer particles (average basis weight: <NUM>/m<NUM>) and having a size of <NUM> x <NUM> (longitudinal direction x lateral direction) was manufactured according to the above manufacturing method. However, in the above manufacturing method, in the step of <FIG>, the absorbent body was substantially formed of only the water-absorbent fibers, and in the steps of <FIG>, the absorbent body was substantially uniformly formed of the water-absorbent fibers and the superabsorbent polymer particles. In the absorbent cores of Examples <NUM> to <NUM>, the amount of the water-absorbent fibers supplied to the step of <FIG> was set to be <NUM>%, <NUM>%, <NUM>%, and <NUM>% of the total amount of the supplied water-absorbent fibers. The basis weights generally corresponded to <NUM>/m<NUM>, <NUM>/m<NUM>, <NUM>/m<NUM>, and <NUM>/m<NUM>. On the other hand, in the absorbent cores of Comparative Examples <NUM> and <NUM>, the amount of the water-absorbent fibers supplied to the step of <FIG> was set to <NUM>% and <NUM>% of the total amount of the supplied water-absorbent fibers. The basis weight generally corresponded to <NUM>, <NUM>/m<NUM>. In the absorbent core, four main groove portions (width: <NUM>) were arranged in the first layer with a space of <NUM>.

Next, each of the absorbent cores was covered with two sheets of tissue (basis weight: <NUM>/m <NUM>, <NUM> × <NUM>) as a core wrap with a hot-melt adhesive interposed therebetween. The thickness of the absorbent core was adjusted by pressing the absorbent core covered with two pieces of tissue with a hydraulic press machine. Thus, the absorbent bodies of Examples <NUM> to <NUM> were formed from the absorbent cores of Examples <NUM> to <NUM>, and the absorbent bodies of Comparative Examples <NUM> and <NUM> were formed from the absorbent cores of Comparative Examples <NUM> and <NUM>. Thereafter, a liquid-permeable sheet (air-through nonwoven fabric) was attached to the second layer side of each absorbent body, and a liquid-impermeable sheet (polyethylene film) was attached to the first layer side. Accordingly, simple absorbent articles of Examples <NUM> to <NUM> were formed from the absorbent bodies of Examples <NUM> to <NUM>, and simple absorbent articles of Comparative Examples <NUM> and <NUM> were formed from the absorbent bodies of Comparative Examples <NUM> and <NUM>.

The absorbent articles of Examples <NUM> to <NUM> and the absorbent articles of Comparative Examples <NUM> and <NUM> were subjected to the following absorbent test, and the absorption rate and liquid return amount (rewet) were evaluated. The results of the evaluation are shown in Table <NUM>.

It should be noted that the absorbent article is set so that the central position of the absorbent body in the longitudinal direction matches the central part of the U-shaped instrument (the position at which the height is the lowest).

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.

Here, in the evaluation, A represents suitable (more satisfactory), B represents suitable, and C represents unsuitable.

Compared with the absorbent articles of Comparative Examples <NUM> and <NUM>, the absorbent articles of Examples <NUM> to <NUM>, which completed the three cycle absorbent test simultaneously satisfied both standards of an absorption time of <NUM>/<NUM> or shorter and a liquid return amount of <NUM>/<NUM> or less. In particular, in Examples <NUM> and <NUM>, the absorption time was <NUM>/<NUM> or shorter, and the liquid return amount was <NUM>/<NUM> or less, which were very satisfactory. Accordingly, it was found that the ratio of the thickness of the base outer side portion to the thickness of the base portion is preferably <NUM>% to <NUM>% and more preferably <NUM>% to <NUM>%.

Examples <NUM> to <NUM> are reference examples not falling under the scope of the present invention.

Claim 1:
An absorbent article having a longitudinal direction, a lateral direction, and a thickness direction, the absorbent article comprising:
an absorbent core (<NUM>) including superabsorbent polymer particles,
wherein the absorbent core (<NUM>) has a non-skin facing surface, and a skin facing surface, and is formed of a first layer (<NUM>) on a non-skin facing surface side, and a second layer (<NUM>) on a skin facing surface side,
the first layer (<NUM>) includes:
a plurality of groove portions (<NUM>) that includes a plurality of main groove portions (<NUM>) extending in the longitudinal direction and penetrating the first layer (<NUM>) in the thickness direction, and
a plurality of base portions (<NUM>) that extend in the longitudinal direction,
each of the plurality of main groove portions (<NUM>) and each of the plurality of base portions (<NUM>) are arranged alternately in the lateral direction,
each of the plurality of base portions (<NUM>) is formed of:
a base inner side portion (<NUM>) adjacent to the non-skin facing surface side of the second layer (<NUM>), and
a base outer side portion (<NUM>) adjacent to the non-skin facing surface side of the base inner side portion (<NUM>), and
an average density of the superabsorbent polymer particles contained in the base outer side portion (<NUM>) is lower than an average density of the superabsorbent polymer particles contained in the base inner side portion (<NUM>)
wherein the second layer (<NUM>) includes:
a plurality of main groove portion corresponding portions (<NUM>) and a plurality of base corresponding portions (<NUM>) arranged at positions overlapping with the plurality of main groove portions (<NUM>) and the plurality of base portions (<NUM>) in the thickness direction, respectively, and charactertised in that:
both an average density of the superabsorbent polymer particles contained in each of the plurality of base portions (<NUM>) and an average density of the superabsorbent polymer particles contained in each of the plurality of main groove portion corresponding portions (<NUM>) are lower than an average density of the superabsorbent polymer particles contained in each of the plurality of base corresponding portions (<NUM>).