JP7514759B2 - Absorbent article and method for manufacturing the absorbent article - Google Patents

Description

The present invention relates to an absorbent sheet, an absorbent article, and a method for manufacturing an absorbent sheet.

For the purpose of improving liquid absorption, a sheet-like material having a water-absorbent polymer disposed between two sheets and an absorbent article having the same have been developed. For example, Patent Document 1 discloses a water-absorbent, water-resistant sheet having a three-layer structure, which is composed of a hydrophobic nonwoven fabric having a water resistance of at least ₁₅₀ mmH2O or more, a hydrophilic sheet having moisture diffusion properties, and an SAP layer made of SAP particles having an average particle size of 500 μm or less, which is interposed between the hydrophobic nonwoven fabric and the hydrophilic sheet.

Patent Document 2 discloses a water-absorbent sheet structure having an absorbent layer containing a water-absorbent resin and an adhesive, sandwiched between nonwoven fabrics from above and below the absorbent layer, the water-absorbent resin content being 100-1000 g/ ^m2 , the mass average particle diameter of the water-absorbent resin being 50-800 μm, the particle diameter velocity index of the water-absorbent resin being 0.12 sec/μm or less, and the peel strength of the water-absorbent sheet structure being 0.05-3.0 N/7 cm. The same document also discloses that this water-absorbent sheet structure can be applied to absorbent articles.

JP 2002-325799 A International Publication No. 2011/086843

The absorbent sheets described in Patent Documents 1 and 2 were aimed at improving performance by focusing on specific performance such as increasing breathability by using hydrophobic nonwoven fabric as a constituent member, or improving liquid absorbency by retaining a water-absorbent polymer in a specified position. However, the absorbent sheets described in these documents did not have a high level of liquid diffusion in the sheet surface direction, liquid absorption, and breathability after liquid absorption in actual use situations.

Therefore, the objective of the present invention is to provide an absorbent sheet that combines liquid diffusion, liquid absorption, and breathability.

The present invention provides an absorbent sheet comprising a first fibrous sheet, a second fibrous sheet, and a water-absorbent polymer disposed between the fibrous sheets,
When the Klemm water absorption heights of both fiber sheets are measured in accordance with JIS P8141, an absorbent sheet is provided in which the Klemm water absorption height of the first fiber sheet is higher than the Klemm water absorption height of the second fiber sheet.

The present invention also provides an absorbent article that includes the absorbent sheet.

The present invention provides an absorbent sheet that combines high levels of liquid diffusion, liquid absorption, and breathability.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the absorbent sheet of the present invention. FIG. 2 is a schematic cross-sectional view showing another embodiment of the absorbent sheet of the present invention. FIG. 3 is a schematic perspective view showing another embodiment of the absorbent sheet of the present invention. FIG. 4 is a schematic diagram showing one embodiment of a manufacturing apparatus used for manufacturing an absorbent sheet.

The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 shows one embodiment of the absorbent sheet of the present invention. The absorbent sheet 1 shown in the figure comprises a first fiber sheet 11, a second fiber sheet 12, and particles of water-absorbent polymer 13 arranged between the two fiber sheets 11 and 12. The particles of water-absorbent polymer 13 shown in the figure are arranged in a plurality in the sheet surface direction. There are no other members on the outer surfaces of either the first fiber sheet 11 or the second fiber sheet 12 shown in the figure, but as described later, other members such as components of an absorbent article may be arranged on the outer surfaces of each fiber sheet 11 and 12.

The first fiber sheet 11 and the second fiber sheet 12 are configured to have different Klemm water absorption heights. In detail, when the Klemm water absorption height is measured based on the measurement method described below, the Klemm water absorption height of the first fiber sheet 11 is higher than the Klemm water absorption height of the second fiber sheet 12. Since each fiber sheet has such physical properties, the first fiber sheet 11 can easily retain liquid in the fiber sheet 11, improving the liquid diffusion in the sheet surface direction, and the diffused liquid can be brought into contact with each absorbent polymer 13 to improve the utilization efficiency of each absorbent polymer 13. As a result, the liquid absorption can be improved. In addition, the second fiber sheet 12 has a lower liquid retention property than the first fiber sheet 11, so that the breathability is improved.

From the viewpoint of making the above-mentioned effect more prominent, the Klemm water absorption height C1 of the first fiber sheet 11 is preferably 20 mm or more, more preferably 25 mm or more, even more preferably 30 mm or more, and 60 mm or less is practical. From the same viewpoint, the Klemm water absorption height C2 of the second fiber sheet 12 is preferably 30 mm or less, more preferably 20 mm or less, and even more preferably 10 mm or less, and 1 mm or more is practical, provided that C1>C2. From the same viewpoint, it is also preferable to use the outer surface of the absorbent sheet 1 on the first fiber sheet 11 side as the liquid receiving surface, which is the surface where the absorbent sheet 1 and the liquid first come into contact. With this configuration, the utilization efficiency of the water-absorbent polymer 13 can be increased compared to the case where the outer surface on the second fiber sheet 12 side is used, and therefore there is an advantage that the liquid absorption is excellent. The Klemm water absorption heights C1 and C2 of each fiber sheet 11 and 12 can be appropriately adjusted, for example, by changing the basis weight or thickness of the fiber sheet or the material of the fiber constituting the fiber sheet.

From the same viewpoint, the difference (C1-C2) between the Klemm water absorption height C1 of the first fiber sheet 11 and the Klemm water absorption height C2 of the second fiber sheet 12 is preferably 10 mm or more, more preferably 15 mm or more, and even more preferably 20 mm or more, provided that C1>C2, and is preferably 50 mm or less, more preferably 45 mm or less, and even more preferably 40 mm or less.

The Klemm water absorption height can be measured, for example, by the following method in accordance with the test method of JIS P8141. In detail, the fiber sheet to be measured is removed from the absorbent sheet 1, taking care not to change the thickness of the fiber sheet. If the fiber sheet to be measured is bonded to another member with an adhesive, the adhesive is solidified by a cooling means such as a cold spray before removal. If the fiber sheet to be measured has absorbent polymer 13 attached, the adhesive is similarly solidified using a cold spray or the like before removing the absorbent polymer 13. The fiber sheet to be measured is cut to a sample with dimensions of 30 mm in width and 100 mm in length or more.

When the planar shape of the absorbent sheet is a shape that is long in one direction, such as a rectangle, the fiber sheet to be measured is cut so that the longitudinal direction of the absorbent sheet and the longitudinal direction of the sample coincide. When the planar shape of the absorbent sheet is a square, the sample is cut so that the direction along any one side coincides with the longitudinal direction of the sample. When the planar shape of the absorbent sheet is a non-polygonal shape, such as a circle, the fiber sheet to be measured is cut at 30° intervals along the imaginary radial lines so that the direction of extension of the imaginary radial lines coincides with the longitudinal direction of the sample, and the sample is prepared. In addition, if the absorbent sheet 1 is incorporated into an absorbent article, the fiber sheet to be measured is removed from the absorbent article and absorbent sheet 1 according to the method described above, and cut to the above dimensions so that the longitudinal direction of the absorbent article and the longitudinal direction of the sample coincide with each other.

Regardless of the planar shape of the absorbent sheet or whether it is incorporated into an absorbent article, when cutting, cutting methods that may crush the sample, such as a push cutter, are likely to affect the results and are not preferred. Therefore, when cutting, use a knife, cutter, razor, etc. to ensure that the cut surface of the sample is not crushed. Using each cut sample, measure the Klemm water absorption height (mm) after 5 minutes in accordance with JIS P8141. The above measurement is performed 10 times for each sample, and the arithmetic average value is the Klemm water absorption height (mm) of the sample.

The fiber sheet used in the present invention is an assembly of fibers, and has a thickness of 5 mm or less measured under a pressure of 1.7 kPa. The thickness of the fiber sheet can be measured, for example, using a laser displacement meter. The fibers constituting each of the fiber sheets 11 and 12 include various fibers such as natural pulp such as wood pulp, cotton, and hemp, modified pulp such as mercerized pulp and chemically crosslinked pulp, synthetic fibers containing resins such as polyethylene and polypropylene, or fibers that have been subjected to hydrophilic or hydrophobic treatment. The form of each of the fiber sheets 11 and 12 is paper, woven fabric, or nonwoven fabric. Each of the fiber sheets 11 and 12 may be single-layered or multi-layered. Each of the fiber sheets 11 and 12 may be composed of only one fiber assembly (whether single-layered or multi-layered), or may have a multi-ply laminated structure in which a first fiber assembly is layered with another fiber assembly or a sheet material other than the fiber assembly. From the viewpoint of achieving both high levels of liquid absorbency and breathability, it is preferable that each of the fiber sheets 11 and 12 be a single-layer sheet.

The absorbent polymer 13 may generally be a hydrogel material capable of absorbing and retaining water, such as a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid. Examples include polyacrylic acid and its salts, and polymethacrylic acid and its salts, specifically, partial sodium salt of acrylic acid polymer. The shape of the absorbent polymer 13 is not particularly limited, and may be, for example, spherical, bunch-like, clump-like, bale-like, fibrous, irregular, or a combination of these particles. From the viewpoint of increasing the uniformity of the dispersion of the absorbent polymer 13 during the manufacture of the absorbent sheet 1 and increasing the liquid absorption performance, it is preferable to use particles of the same shape for the absorbent polymer 13, and it is also preferable for the particles to be spherical.

In the absorbent sheet 1 having the above configuration, the Klemm water absorption height of the first fiber sheet 11 is different from the Klemm water absorption height of the second fiber sheet 12. Since the Klemm water absorption height of the first fiber sheet 11 is high, the first fiber sheet 11 can easily retain liquid and improve the liquid diffusion in the sheet surface direction. As a result, the liquid retained in the first fiber sheet 11 can be absorbed by each particle of the water-absorbing polymer 13, improving the utilization efficiency of the water-absorbing polymer 13 and increasing the liquid absorption. In addition, the Klemm water absorption height of the second fiber sheet 12 is lower than that of the first fiber sheet 11, and the liquid retention of the second fiber sheet 12 itself is low, so that the steam generated by the evaporation of the absorbed liquid can be easily released to the outside through the second fiber sheet 12, and the absorbent sheet 12 has good breathability. This point is advantageous in that, as described later, when an absorbent article is made with the absorbent sheet 1, the stuffiness of the absorbent article when worn is reduced and the wearer's feeling of use is improved.

From the viewpoint of making the above-mentioned effect prominent, it is preferable that the airflow resistance R2 of the second fiber sheet 12 is lower than the airflow resistance R1 of the first fiber sheet 11. In detail, the airflow resistance R1 of the first fiber sheet 11 is preferably 0.1 kPa·s/m or more, more preferably 0.2 kPa·s/m or more, even more preferably 0.3 kPa·s/m or more, and is preferably 0.8 kPa·s/m or less, more preferably 0.6 kPa·s/m or less, even more preferably 0.4 kPa·s/m or less. Furthermore, the airflow resistance R2 of the second fiber sheet 12 is preferably 0.005 kPa·s/m or more, more preferably 0.01 kPa·s/m or more, even more preferably 0.02 kPa·s/m or more, and is preferably 0.3 kPa·s/m or less, more preferably 0.2 kPa·s/m or less, and even more preferably 0.1 kPa·s/m or less, provided that the airflow resistance R2 is lower than the airflow resistance R1 of the first fiber sheet 11. The lower the airflow resistance, the higher the air permeability, and can be measured, for example, using a KES-F8 air permeability tester (manufactured by Kato Tech Co., Ltd., AUTOMATIC AIR-PERMEABILITY TESTER KES-F8-AP1).

From the same viewpoint, the difference (R1-R2) between the airflow resistance R1 of the first fiber sheet 11 and the airflow resistance R2 of the second fiber sheet 12, on condition that R1>R2, is preferably 0.07 kPa·s/m or more, more preferably 0.15 kPa·s/m or more, even more preferably 0.2 kPa·s/m or more, and is preferably 0.7 kPa·s/m or less, more preferably 0.5 kPa·s/m or less, even more preferably 0.4 kPa·s/m or less.

From the viewpoint of facilitating the diffusion of liquid toward the sheet surface, further increasing the utilization efficiency of the water-absorbent polymer 13, and realizing high liquid absorbency, it is preferable that the first fiber sheet 11 is paper. Paper refers to paper made by agglutinating plant fibers such as pulp and other fibers, preferably wet, in accordance with the provisions of JIS P0001.

When the first fiber sheet 11 is paper, it is preferable that it is creped (folded), and the crepe ratio F1 of the first fiber sheet 11 is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more, with 30% or less being realistic. Furthermore, by setting the crepe ratio at such a level, the capillary force of the fiber sheet can be increased, so that a fiber sheet having the above-mentioned Klemm water absorption height can be easily obtained. Such a fiber sheet can be obtained, for example, by subjecting the fiber sheet to a known crepe treatment so as to achieve the above-mentioned crepe ratio.

The crepe ratio can be measured by the underwater elongation method, for example, based on the following method. The measurement is performed at 23±2°C and a relative humidity of 50±5%, and the sample is stored in the same environment for 24 hours or more before the measurement. The fiber sheet to be measured is cut into a size of 25 mm in the direction in which the wrinkles extend and 100 mm in the direction perpendicular to the direction to prepare a measurement sample, which is immersed in water for 1 minute and then pulled out, and the crepe ratio is calculated from the change in dimension in the perpendicular direction using the following formula. The measurement is performed three times, and the arithmetic average value is the crepe ratio (%). If a size of 100 mm cannot be secured in the perpendicular direction, the crepe ratio can be obtained by cutting into a size of at least 30 mm in the perpendicular direction.
Crepe rate (%)=((dimension after immersion in water (mm))/(dimension before immersion in water (mm))−1)×100

When the first fiber sheet 11 is paper, the interfiber distance of the constituent fibers is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, and 5 μm or more is realistic. By having the interfiber distance in this range, it is easier to increase the apparent density of the first fiber sheet 11, and a fiber sheet having the above-mentioned Klemm water absorption height can be easily obtained.

The interfiber distance of a fiber sheet can be calculated, for example, by the following formula (1) based on Wrotnowski's assumptions. The following formula (1) is generally used to calculate the interfiber distance of a fiber assembly. Under Wrotnowski's assumptions, the fibers are cylindrical and are regularly arranged without crossing each other. When the fiber sheet to be measured has a single-layer structure, the interfiber distance of the fiber sheet can be calculated by the following formula (1) based on the thickness t and basis weight W of the fiber sheet, as well as the fiber density ρ and fiber diameter D.

When the fiber sheet to be measured has a multi-layer structure, the inter-fiber distance of the multi-layer sheet is determined according to the following procedure.
First, the inter-fiber distance of each fiber layer constituting the multi-layer structure is calculated by the following formula (1). In this case, the thickness t, basis weight W, fiber density ρ, and fiber diameter D used in the following formula (1) are those of the layer to be measured. The thickness t, basis weight W, and fiber diameter D are each the arithmetic average value of the measured values at multiple measurement points.
The thickness t (mm) is measured by the following method. First, the sheet to be measured is cut into a length of 50 mm x width of 50 mm to prepare a cut piece of the sheet. However, when a sheet is taken from a small absorbent article, etc., a cut piece of this size cannot be prepared as the sheet to be measured, a cut piece as large as possible is prepared. Next, the cut piece is placed on a flat plate, a flat glass plate is placed on it, and a weight is evenly placed on the glass plate so that the load including the glass plate is 49 Pa, and the thickness of the cut piece is measured. The measurement environment is a temperature of 20 ± 2 ° C., a relative humidity of 65 ± 5%, and a microscope (Keyence Corporation, VHX-1000) is used as the measuring instrument. To measure the thickness of the cut piece, first, an enlarged photograph of the cut surface of the cut piece is obtained. An object of known dimensions is simultaneously photographed on this enlarged photograph. Next, a scale is set on the enlarged photograph of the cut surface of the cut piece, and the thickness of the cut piece, i.e., the thickness of the sheet to be measured, is measured. The above operation is carried out three times, and the arithmetic average of the three measurements is taken as the thickness t of the sheet to be measured. If the sheet to be measured is a laminate, the boundary between the laminate and the fiber is determined based on the difference in fiber diameter and/or fiber density, and the thickness is calculated.

Basis weight W (g/ ^m2 ) is determined by cutting the sheet to be measured to a predetermined size (e.g., 12 cm x 6 cm), measuring the mass, and then dividing the measured mass by the area determined from the predetermined size ("Basis weight W (g/ ^m2 ) = Mass / Area determined from predetermined size"). The measurement is performed four times, and the arithmetic average value is taken as the basis weight.
The density ρ (g/cm ³ ) of the fiber is measured using a density gradient tube in accordance with the density gradient tube method in JIS L1015.
The fiber diameter D (μm) is determined by measuring ten cross sections of the fiber cut in a direction perpendicular to the fiber extension direction using a Hitachi S-4000 field emission scanning electron microscope, and the arithmetic average value is taken as the fiber diameter.
Next, the inter-fiber distance of each layer is multiplied by the proportion of the thickness of that layer in the total thickness of the multilayer structure, and the numerical values thus obtained for each layer are added up to determine the inter-fiber distance of the constituent fibers of the desired multilayer sheet.

When the first fiber sheet 11 is paper, it is also preferable that the fibers of the paper have a unidirectional orientation tendency. With this configuration, a single fiber sheet can form both a direction in which the Klemm water absorption height is high and a direction in which the Klemm water absorption height is low, so that the liquid diffusion can be increased in the direction in which the orientation tendency is present, and the utilization efficiency of the water-absorbent polymer can be increased, and unintended diffusion of liquid can be prevented in a direction perpendicular to the direction in which the orientation tendency is present. In particular, as described below, when an absorbent sheet 1 having an orientation tendency in one direction is incorporated so that the direction in which the orientation tendency is present and the longitudinal direction of the absorbent article coincide with each other, the liquid diffusion in the longitudinal direction of the absorbent article can be increased, and the utilization efficiency of the water-absorbent polymer can be increased, and unintended diffusion in the width direction of the absorbent article can be suppressed, thereby preventing liquid leakage from the width direction. The orientation tendency is a value measured according to a measurement method described below, and is preferably 60% or more, more preferably 70% or more.

The orientation of the fibers constituting the fiber sheet is measured using a tension and compression tester (AG-IS, manufactured by Shimadzu Corporation). A test piece with dimensions of 150 mm length x 50 mm width is cut out along one direction of the fiber sheet and the direction perpendicular to that. If the fiber sheet is square or rectangular in shape, the test piece may be cut out to the above dimensions with the direction along any one side as the longitudinal direction and the direction perpendicular to that direction as the width direction. The test piece is pulled at a tensile speed of 300 mm/min with a chuck distance of 100 mm so as to elongate the test piece in the longitudinal direction, and the maximum load (N) at break is recorded. This experiment is performed using five test pieces, the maximum load of each is measured, and the arithmetic average of these values is taken as the longitudinal tensile strength (N). Similarly, five test pieces having the above dimensions are pulled so as to elongate them in the width direction, and the maximum load (N) at break of each is measured, and the arithmetic average of these values is taken as the width tensile strength (N).

Based on the longitudinal tensile strength and transverse tensile strength obtained by the above method, the orientation tendency is calculated from the following formula (2). When the orientation tendency calculated from the following formula (2) is 50% or more, it is considered that "the test piece has an orientation tendency along the longitudinal direction", and when the orientation tendency calculated from the following formula (2) is less than 50%, it is considered that "the test piece has an orientation tendency along the width direction". The longitudinal direction and transverse direction of the test piece correspond to one direction and a direction perpendicular to the same in the cut fiber sheet, respectively.
Orientation tendency (%) = 100 × ([longitudinal tensile strength (N)] / ([longitudinal tensile strength (N)] + [transverse tensile strength (N)])) ... formula (2)

Regarding the second fiber sheet 12, it is preferable that the crepe rate F2 of the second fiber sheet 12 measured by the above-mentioned method is less than 1%. By setting the second fiber sheet 12 to such a crepe rate, it is possible to make the second fiber sheet 12 less likely to retain liquid, resulting in a sheet with even higher breathability, and also to easily obtain a fiber sheet with a lower Klemm water absorption height compared to the first fiber sheet 11.

From the viewpoint of achieving both the expression of capillary force in the first fiber sheet 11 and the breathability of the second fiber sheet 12, the difference (F1-F2) between the crepe rate F1 of the first fiber sheet 11 and the crepe rate F2 of the second fiber sheet is preferably 4% or more, more preferably 9% or more, and even more preferably 14% or more, with 30% or less being realistic, provided that F1>F2.

The second fiber sheet 12 is preferably a hydrophilic nonwoven fabric made of a fiber aggregate of hydrophilic fibers. By using a fiber sheet made of hydrophilic fibers, the absorbed liquid can easily reach the outer surface of the second fiber sheet 12, making it easier for the liquid to come into contact with the outside air and efficiently promoting evaporation of the liquid. Furthermore, by using a nonwoven fabric as the fiber sheet, the liquid retention of the fiber sheet can be reduced, further improving breathability.

In the absorbent sheet 1, from the viewpoint of easily forming an absorbent sheet having a direction in which the Klemm water absorption height is high and a direction in which the Klemm water absorption height is low, thereby increasing the liquid diffusibility and further increasing the utilization efficiency of the water-absorbent polymer, and a direction in which the unintended diffusion of liquid is further suppressed, it is preferable that the orientation tendency of the fibers constituting the first fiber sheet 11 and the orientation tendency of the fibers constituting the second fiber sheet 12 are consistent with each other. In detail, when the orientation tendency is calculated by the above-mentioned method for each test piece cut in the same direction from each of the fiber sheets 11 and 12, the orientation tendency of each of the fiber sheets 11 and 12 is preferably 60% or more, more preferably 70% or more, in the same direction.

Figures 2 and 3 show another embodiment of the absorbent sheet 1. In the following explanation, only the parts that differ from the above-mentioned embodiment will be explained, and the above explanation will be applied to other parts as appropriate. Also, the same symbols are used for the same parts as the above-mentioned embodiment.

The absorbent sheet 1 shown in Figs. 2 and 3 comprises a first fiber sheet 11, a second fiber sheet 12, and a plurality of particles of water-absorbent polymer 13 arranged between the two fiber sheets 11 and 12. In addition, it is preferable that the first fiber sheet 11 and the second fiber sheet 12 are bonded to each other with an adhesive 15. This configuration increases the adhesive strength between the two fiber sheets 11 and 12, and increases the strength of the absorbent sheet 1. The adhesive 15 shown in Fig. 2 is arranged on the surfaces of each of the fiber sheets 11 and 12 that face the water-absorbent polymer 13. The outer surfaces of the first fiber sheet 11 and the second fiber sheet 12 shown in the figure are both free of the adhesive 15 and other members.

In particular, when the two fibrous sheets 11, 12 are joined to each other by the adhesive 15, it is preferable that the first fibrous sheet 11 and the second fibrous sheet 12 have a portion 17 where the first fibrous sheet 11 and the second fibrous sheet 12 are directly joined to each other by the adhesive 15 without the water-absorbent polymer 13 (hereinafter, this is also simply referred to as the "directly joined portion 17"), and a portion 18 where the first fibrous sheet 11 and the second fibrous sheet 12 are joined to each other by the adhesive 15 via the water-absorbent polymer 13 (hereinafter, this is also referred to as the "indirectly joined portion 18"). With this configuration, the water-absorbent polymer 13 can be held in a predetermined position in the absorbent sheet 1, and unintended movement or uneven distribution of the water-absorbent polymer 13 can be further reduced, and the liquid absorbency of the absorbent sheet 1 can be further improved.

The direct bonded areas 17 shown in Figures 2 and 3 are formed in the gaps between the particles of the water-absorbent polymer 13 in the area where the water-absorbent polymer 13 is arranged. When viewed in cross section in the sheet thickness direction, the direct bonded areas 17 are formed by the adhesive 15 in the form of columns that directly bond the two fiber sheets 11, 12 together. As shown in Figure 3, when the absorbent sheet 1 is viewed in the sheet planar direction, multiple direct bonded areas 17 are formed in a regular or irregular scattered pattern.

As shown in FIG. 2, the indirectly bonded area 18 is an area where the area where the adhesive 15 is applied on the first fiber sheet 11, the area where the water-absorbent polymer 13 is present, and the area where the adhesive 15 is applied on the second fiber sheet 12 overlap in the thickness direction when the absorbent sheet 1 is viewed in cross section.

As the adhesive 15, it is preferable to use one that has flexibility that can expand in response to the swelling change caused by the liquid absorption of the water-absorbing polymer 13. Examples of such raw materials include acrylic adhesives containing one or more (co)polymers of vinyl monomers such as 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, cyanoacrylate, vinyl acetate, methyl methacrylate, etc. (such as ethylene-vinyl acetate copolymers), silicone adhesives containing polydimethylsiloxane polymers, and rubber adhesives such as natural rubber adhesives containing natural rubber, isoprene adhesives containing one or more polyisoprene, chloroprene, etc., styrene-butadiene copolymers (SBR), styrene-isoprene-styrene block copolymers (SIS), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene-butadiene-styrene block copolymers (SEBS), and styrene-ethylene-propylene-styrene block copolymers (SEPS). These may be used alone or in combination of two or more. As shown in FIG. 2, when adhesive 15 is applied to the surface of each of the fiber sheets 11 and 12 facing the water-absorbent polymer 13, the adhesive applied to the first fiber sheet 11 and the adhesive applied to the second fiber sheet 12 may be the same or different.

Among these, it is preferable to use a rubber-based adhesive as the adhesive 15, which has excellent flexibility and elasticity, and maintains the direct bonding state between the fiber sheets 11 and 12 even after the water-absorbent polymer swells, and from the viewpoint of exerting a contractile force to easily hold the water-absorbent polymer 13 between the two fiber sheets 11 and 12, and among the rubber-based adhesives, it is even more preferable to use a styrene-based adhesive.

From the viewpoint of achieving both the flexibility of the adhesive and its adhesion to the sheet, it is preferable that the adhesive 15 is a hot melt adhesive. For example, the hot melt adhesive may contain, in addition to the various adhesives described above, a tackifier such as petroleum resin or polyterpene resin, a plasticizer such as paraffin-based oil, and, as necessary, an antioxidant such as a phenol-based, amine-based, phosphorus-based, or benzimidazole-based.

As shown in FIG. 2, it is preferable that adhesive 15 is applied to each of the surface of the first fiber sheet 11 facing the water-absorbent polymer 13 and the surface of the second fiber sheet 12 facing the water-absorbent polymer 13. With this configuration, the adhesives applied to the fiber sheets 11 and 12 are bonded to each other to efficiently form direct bonding sites 17 on the absorbent sheet 1, and it is possible to simultaneously support the water-absorbent polymer 13 at an appropriate position and ensure a space in which the water-absorbent polymer 13 can swell. In addition, the adhesive 15 can be easily present in the gaps between the fibers that make up the fiber sheets 11 and 12, which has the advantage that peeling at the interface between the fiber sheets 11 and 12 and the adhesive 15 is less likely to occur.

As shown in Figs. 2 and 3, it is preferable that the application area of the adhesive 15 on the second fiber sheet 12 is larger than that of the first fiber sheet 11. With this configuration, the absorbent polymer 13 is uniformly held on the second fiber sheet 12, which has a larger application area of the adhesive 15 than the first fiber sheet 11, and the unintended movement or falling off of the absorbent polymer 13 is suppressed, and liquid permeability from the first fiber sheet 11, which has a smaller application area of the adhesive 15 than the second fiber sheet 12, is ensured, and the liquid absorbency can be further improved. The application areas of both fiber sheets 11 and 12 are compared by stacking both fiber sheets 11 and 12 having the same shape and area so that there are no non-overlapping parts of the sheets. The application area of the adhesive 15 can be calculated, for example, by visualizing the presence of the adhesive 15 on the surface of each fiber sheet 11, 12 on which the adhesive 15 is attached using ink toner or the like, and using image processing software or the like to calculate the area of the part. If it is difficult to distinguish, you can use cold spray or similar to remove both sheets before measuring.

Focusing on the areas where the adhesive 15 is applied on each of the fiber sheets 11 and 12, it is preferable that the first basis weight of the adhesive 15 applied to the first fiber sheet 11 is higher than the second basis weight of the adhesive 15 applied to the second fiber sheet 12. This configuration makes it easier to form a direct bonded area 17 with the second fiber sheet 12 via the adhesive 15 applied to the first fiber sheet 11, and also makes it possible to hold the absorbent polymer 13 in an appropriate position via the adhesive 15 applied to the second fiber sheet 12, thereby further improving the liquid absorption performance.

From the same viewpoint, the first basis weight is preferably 400 g/ ^m2 or less, more preferably 250 g/ ^m2 or less, even more preferably 100 g/ ^m2 or less, and more preferably 20 g/ ^m2 or more. The second basis weight is preferably 30 g/ ^m2 or less, more preferably 15 g/ ^m2 or less, even more preferably 10 g/ ^m2 or less, and more preferably 2 g/ ^m2 or more.

The first and second basis weights are measured and calculated only for the application portions of the fibrous sheets 11 and 12 to which the adhesive 15 is applied. In detail, after the fibrous sheets 11 and 12 in the absorbent sheet 1 are separated, the mass A1 (g) of the first fibrous sheet 11 to which the adhesive 15 is attached is measured. In addition, the portion where the adhesive 15 is present is visualized on the surface of the first fibrous sheet 11 to which the adhesive 15 is attached using ink toner or the like, and in this state, the total area S (m ² ) of the portion where the adhesive 15 is present is measured using image processing software. Next, the first fibrous sheet 11 is immersed in an organic solvent to measure the mass A2 (g) of the fibrous sheet after dissolving the attached adhesive 15. The first basis weight (g/m ² ) can be calculated as "(A1-A2)/S". Similarly, the second basis weight (g/m ² ) can be calculated for the second fibrous sheet 12 in the same manner as described above.

From the viewpoint of improving liquid absorption, the thickness of the absorbent sheet is preferably 0.3 mm or more, more preferably 0.6 mm or more. From the viewpoint of improving the user's experience when using the absorbent sheet or an absorbent article containing the sheet, the thickness of the absorbent sheet is preferably 4 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less. The above-mentioned thickness of the absorbent sheet is the thickness of the entire absorbent sheet measured under the application of a pressure of 1.7 kPa.

The absorbent sheet 1 of the embodiment shown in FIG. 1, 2 and 3 may be used as is. In this case, the absorbent sheet 1 may be used alone, or multiple sheets may be used in a laminated state. When multiple absorbent sheets 1 are used, only the absorbent sheet 1 of the embodiment shown in FIG. 1 or only the absorbent sheet 1 of the embodiment shown in FIG. 2 and FIG. 3 may be used, or the absorbent sheet 1 of the embodiment shown in FIG. 1 may be used in combination with the absorbent sheet 1 of the embodiment shown in FIG. 2 and FIG. 3.

The absorbent sheet 1 of the embodiment shown in FIG. 1, FIG. 2 and FIG. 3 can be used as a component of an absorbent article. Typically, an absorbent article has a longitudinal direction along the front-rear direction of a wearer and a width direction perpendicular to the longitudinal direction, and includes a top sheet and a back sheet, and can be used with the absorbent sheet of the present invention disposed between the top sheet and the back sheet. Examples of absorbent articles include incontinence pads, sanitary napkins, and disposable diapers. From the viewpoint of improving the liquid absorption of an absorbent article, when the absorbent sheet 1 is used as a component of an absorbent article, the absorbent sheet 1 may be used in a stacked state in multiple sheets, or an absorbent body may be further stacked in addition to the absorbent sheet 1. When the absorbent sheet 1 is used by stacking an absorbent body, it is preferable that the absorbent body is disposed at least in the central region of the absorbent sheet 1.

The top sheet used in an absorbent article is a sheet that constitutes the surface facing the skin of a wearer wearing the absorbent article when the absorbent article is worn in the proper position (hereinafter, this is also referred to as the "skin-facing surface"), and the back sheet is a sheet that constitutes the surface facing away from the skin of a wearer wearing the absorbent article (hereinafter, this is also referred to as the "non-skin-facing surface"). The top sheet and back sheet used in an absorbent article can be any sheet that has been conventionally used in absorbent articles, without any particular restrictions. For example, various liquid-permeable nonwoven fabrics and perforated films can be used as the top sheet. For the back sheet, a resin film that is poorly permeable to liquids or water-repellent, or a laminate of a resin film and a nonwoven fabric, etc. can be used.

The absorbent body used in absorbent articles has an absorbent core. The absorbent core is composed of, for example, a pile of hydrophilic fibers such as cellulose including pulp, a mixed pile of the hydrophilic fibers and a water-absorbent polymer, a pile of water-absorbent polymer, or the like. At least the skin-facing surface of the absorbent core may be covered with a liquid-permeable core wrap sheet, or the entire surface including the skin-facing surface and the non-skin-facing surface may be covered with the core wrap sheet. As the core wrap sheet, for example, tissue paper made of hydrophilic fibers or liquid-permeable nonwoven fabric can be used.

In particular, when the absorbent sheet 1 is used as a component of an absorbent article, it is preferable that the first fiber sheet 11 in the absorbent sheet 1 is arranged so that it becomes the liquid receiving surface. In other words, it is preferable to arrange the absorbent sheet 1 so that the first fiber sheet 11 is arranged on the skin-facing side. In addition, when the first fiber sheet 11 is creped, it is also preferable that the direction in which the crepe extends and the longitudinal direction of the absorbent article are arranged so that they coincide with each other. Furthermore, when the constituent fibers of the first fiber sheet 11 or both fiber sheets 11 and 12 have an orientation tendency in one direction, it is also preferable that the direction in which the orientation tendency is present and the longitudinal direction of the absorbent article are arranged so that they coincide with each other. By arranging the absorbent sheet in this way, the liquid drawing ability from the top sheet side and the liquid retention ability of the absorbent sheet are both improved, resulting in an absorbent article with high liquid absorption. In addition, it is possible to easily draw liquid that has adhered to and permeated the top sheet to the absorbent sheet side, thereby improving the dry feeling of the top sheet, which has the advantage of improving the feeling of use of the absorbent article by the wearer. Furthermore, it also has the advantage of making it easier for steam derived from absorbed liquid to evaporate from the second fiber sheet 12 side, reducing stuffiness when the absorbent article is worn, improving the comfort of the wearer of the absorbent article. Evaporation of steam from the second fiber sheet 12 side is particularly effective when a moisture-permeable back sheet is used for the absorbent article.

The above has been a description of the absorbent sheet of the present invention and an absorbent article including said sheet. Below, a preferred manufacturing method for the absorbent sheet of the present invention will be described. FIG. 4 shows one embodiment of a manufacturing device 100 suitable for use in this manufacturing method. This manufacturing method is suitable for manufacturing an absorbent sheet 1 in which both fiber sheets 11, 12 are bonded to each other with an adhesive 15.

The manufacturing device 100 shown in FIG. 4 includes a first web roll 110 and a second web roll 120. The first web roll 110 is configured to unroll a long strip-shaped first fiber sheet 11 along the conveying direction R so that it can be supplied to a first adhesive application section 130, which will be described later. The second web roll 120 is configured to unroll a long strip-shaped second fiber sheet 12 along the conveying direction R so that it can be supplied to a second adhesive application section 140, which will be described later.

The manufacturing apparatus 100 includes a first adhesive applicator 130 and a second adhesive applicator 140. The first adhesive applicator 130 can continuously or intermittently apply adhesive 15 to one side of the first fiber sheet 11 supplied from the first raw roll 110. The first adhesive applicator 130 shown in the figure is configured to apply adhesive 15 intermittently. The second adhesive applicator 140 can continuously or intermittently apply adhesive 15 to one side of the second fiber sheet 12 supplied from the second raw roll 120. The second adhesive applicator 140 shown in the figure is configured to apply adhesive 15 continuously. In FIG. 4, the adhesive 15 applied to the first fiber sheet 11 and the adhesive 15 applied to the second fiber sheet 12 are both shown to be the same type of adhesive, but different types of adhesives may be used.

The manufacturing apparatus 100 is equipped with a polymer spraying section 150. The polymer spraying section 150 is located above the second fiber sheet 12 and is capable of spraying the water-absorbing polymer 13 onto the surface of the second fiber sheet 12 on which the adhesive 15 has been applied.

The manufacturing apparatus 100 preferably further includes a press roll 160. The press roll 160 presses the laminate in which the first fiber sheet 11 is superimposed on the second fiber sheet 12 containing the water-absorbent polymer 13 via a guide roll 161. This makes it possible to form a long strip-shaped absorbent sheet 1 with many direct bonded portions 17.

The manufacturing apparatus 100 may be provided with a sheet cutting section downstream of the press roll 160 (not shown). The sheet cutting section cuts the long strip-shaped absorbent sheet 1 at a predetermined position to form an absorbent sheet 1 having a predetermined dimension. As the sheet cutting section, for example, a cutter roll having a cutter blade extending in a direction perpendicular to the conveying direction R can be used.

The manufacturing method of the absorbent sheet using the manufacturing apparatus 100 having the above-mentioned configuration is as follows. First, adhesive 15 is applied to at least one of the two fiber sheets 11 and 12, preferably to one side of the first fiber sheet 11 and one side of the second fiber sheet 12. In the embodiment shown in FIG. 4, adhesive 15 supplied from the first adhesive application unit 130 is applied to one side of the first fiber sheet 11. Also, adhesive 15 supplied from the second adhesive application unit 140 is applied to one side of the second fiber sheet 12. The adhesive 15 may be applied to one fiber sheet and then to the other fiber sheet in sequence, or may be applied to each of the fiber sheets 11 and 12 simultaneously. When adhesive 15 is applied to only one of the two fiber sheets 11 and 12, adhesive 15 may be supplied and applied from either the first adhesive application unit 130 or the second adhesive application unit 140.

From the viewpoint of efficiently forming the direct bonding portion 17 on the absorbent sheet 1 by bonding the adhesives applied to each fiber sheet 11, 12, it is preferable that the application method in the first adhesive application unit 130 is a method that can be adjusted to increase the basis weight of the adhesive 15 in the applied portion of the adhesive 15, and in particular, it is preferable to adopt a pattern application method such as spiral application, summit application, omega application, etc., which forms a non-applied portion of the adhesive 15. From the same viewpoint, it is preferable that the application method in the second adhesive application unit 140 is a method that can apply the adhesive 15 continuously at a low basis weight, and in particular, it is preferable to adopt spray application or coater application, and it is particularly preferable to adopt coater application. The basis weight applied to each fiber sheet 11, 12 may be adjusted to be within the above-mentioned range.

Next, the water-absorbent polymer 13 is sprayed from the polymer spraying unit 150 onto the surface of the second fiber sheet 12 to which the adhesive 15 has been applied. The water-absorbent polymer 13 is supported by adhering it to the adhesive 15 on the second fiber sheet 12. It is preferable that the water-absorbent polymer 13 is sprayed uniformly in the sheet surface direction of the second fiber sheet 12. When spraying the water-absorbent polymer 13, the amount of water-absorbent polymer 13 sprayed in the sheet surface direction of the second fiber sheet 12 may be changed depending on the desired absorbent sheet 1.

Then, the fiber sheets 11, 12 are overlapped so that the adhesive-coated surfaces of the fiber sheets 11, 12 face each other. The laminate obtained by overlapping the fiber sheets 11, 12 has the water-absorbent polymer 13 disposed between the two fiber sheets 11, 12. If necessary, this laminate may be supplied directly to the sheet cutting section without being introduced into the press roll 160 to form the absorbent sheet of the present invention. Alternatively, the fiber sheets 11, 12 may be introduced directly into the press roll 160 without being overlapped in advance, and overlapped while being pressed.

Then, the overlapping fiber sheets 11, 12 are introduced between the press rolls 160 and pressed. This makes it easier to directly bond the adhesive 15 applied to each fiber sheet 11, 12, and the direct bonding area 17 can be easily formed. In addition, the adhesion between the water-absorbent polymer 13 and the adhesive 15 can be improved. As a result, both the liquid absorbency and the water-absorbent polymer retention can be improved.

From the viewpoint of efficiently forming the direct bonded portion 17 while suppressing unintended destruction of the product, it is preferable to press each of the fiber sheets 11, 12 with a relatively high pressure using a press roll 160 with a soft surface. By pressing each of the fiber sheets 11, 12 under such conditions, the peripheral surface of the press roll can be made to follow the unevenness of each of the fiber sheets 11, 12 caused by the water-absorbent polymer 13, so that pressure can be efficiently applied so as to facilitate direct bonding of the adhesive 15 applied to each of the fiber sheets 11, 12. Examples of materials that can be used for such a press roll 160 include hard rubber, silicone rubber, and silicone sponge.

Finally, the long strip of absorbent sheet 1 is cut to a specified size by the sheet cutting section to produce the absorbent sheet of the present invention.

When the absorbent sheet 1 is manufactured without using the adhesive 15, it can be manufactured, for example, by the method shown in FIG. 3 of JP-A-8-246395. Specifically, one fiber sheet is made by wet papermaking or the like, and the water-absorbent polymer 13 is sprayed onto the wet fiber sheet to cause the water-absorbent polymer 13 to develop adhesiveness due to water absorption, and to fix it to the fiber sheet. Thereafter, the other fiber sheet is superimposed on the surface onto which the water-absorbent polymer 13 has been sprayed to form a laminate, and this laminate is dried by a known drying means such as a Yankee dryer, thereby manufacturing the absorbent sheet.

In another embodiment in which the absorbent sheet 1 is manufactured without using adhesive 15, the absorbent polymer 13 is sprayed onto one of the fiber sheets, and then water is further sprayed onto the sheet to cause the absorbent polymer 13 to become sticky and to be fixed to the fiber sheet. The absorbent sheet 1 can then be manufactured by overlapping the other fiber sheet onto the surface onto which the absorbent polymer 13 has been sprayed to form a laminate, and drying this laminate by the drying means described above.

Through the above steps, the absorbent sheet of the present invention is manufactured. This absorbent sheet has high levels of liquid diffusion, liquid absorption, and breathability. In a preferred embodiment of the present invention, the water-absorbent polymer is fixed in a predetermined position while still being able to swell sufficiently, so that high liquid absorption performance can be effectively achieved.

The present invention has been described above based on a preferred embodiment, but the present invention is not limited to the above embodiment.

In addition to the above-described embodiment of the present invention, the following absorbent sheets and absorbent articles are disclosed.

＜1＞
An absorbent sheet comprising a first fibrous sheet, a second fibrous sheet, and a water-absorbent polymer disposed between the fibrous sheets,
An absorbent sheet, wherein when the Klemm water absorption height of each fiber sheet is measured in accordance with JIS P8141, the Klemm water absorption height of the first fiber sheet is higher than the Klemm water absorption height of the second fiber sheet.

＜2＞
The absorbent sheet according to <1>, wherein the first fiber sheet has a Klemm water absorption height of 20 mm or more, and the second fiber sheet has a Klemm water absorption height of 30 mm or less.
＜3＞
The absorbent sheet according to <1> or <2>, wherein the Klemm water absorption height of the first fiber sheet is preferably 20 mm or more, more preferably 25 mm or more, and even more preferably 30 mm or more, and practically 60 mm or less.
＜4＞
The absorbent sheet according to any one of <1> to <3>, wherein the Klemm water absorption height of the second fiber sheet is preferably 30 mm or less, more preferably 20 mm or less, and even more preferably 10 mm or less, and a practical value is 1 mm or more.
＜5＞
The absorbent sheet according to any one of <1> to <4> above, wherein the difference (C1-C2) between the Klemm absorption height C1 of the first fiber sheet 11 and the Klemm absorption height C2 of the second fiber sheet 12 is preferably 10 mm or more, more preferably 15 mm or more, even more preferably 20 mm or more, and is preferably 50 mm or less, more preferably 45 mm or less, even more preferably 40 mm or less.

＜6＞
The absorbent sheet according to any one of <1> to <5>, wherein, when the airflow resistance of each fiber sheet is measured using a KES-F8 air permeability tester, the airflow resistance of the second fiber sheet is lower than the airflow resistance of the first fiber sheet.
＜７＞
The absorbent sheet according to <6> above, wherein the difference (R1-R2) between the air flow resistance R1 of the first fiber sheet 11 and the air flow resistance R2 of the second fiber sheet 12 is preferably 0.07 kPa·s/m or more, more preferably 0.15 kPa·s/m or more, even more preferably 0.2 kPa·s/m or more, and is preferably 0.7 kPa·s/m or less, more preferably 0.5 kPa·s/m or less, even more preferably 0.4 kPa·s/m or less.
＜8＞
The absorbent sheet according to any one of <1> to <7> above, wherein the first fiber sheet has an air resistance of preferably 0.1 kPa·s/m or more, more preferably 0.2 kPa·s/m or more, and even more preferably 0.3 kPa·s/m or more.
＜9＞
The absorbent sheet according to any one of <1> to <8>, wherein the first fiber sheet has an air resistance of preferably 0.8 kPa·s/m or less, more preferably 0.6 kPa·s/m or less, and even more preferably 0.4 kPa·s/m or less.
＜10＞
The absorbent sheet according to any one of <1> to <9>, wherein the second fiber sheet has an air resistance of preferably 0.005 kPa·s/m or more, more preferably 0.01 kPa·s/m or more, and even more preferably 0.02 kPa·s/m or more.
<11>
The absorbent sheet according to any one of <1> to <10> above, wherein the second fiber sheet has an air resistance of preferably 0.3 kPa·s/m or less, more preferably 0.2 kPa·s/m or less, and even more preferably 0.1 kPa·s/m or less.

＜12＞
The first fiber sheet is paper having a crepe rate of 5% or more;
The absorbent sheet according to any one of <1> to <11>, wherein the second fiber sheet has a crepe rate of less than 1%.
＜13＞
The absorbent sheet according to <12> above, wherein the first fiber sheet is preferably creped (folded), and the crepe ratio is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more, and realistically 30% or less.
＜14＞
The absorbent sheet according to item <12> or <13>, wherein the difference (F1-F2) between the crepe rate F1 of the first fiber sheet 11 and the crepe rate F2 of the second fiber sheet is preferably 4% or more, more preferably 9% or more, and even more preferably 14% or more, and realistically 30% or less.

＜15＞
The absorbent sheet according to any one of <12> to <14>, wherein the distance between fibers of the paper is 30 μm or less.
＜16＞
The absorbent sheet according to any one of <12> to <15>, wherein the inter-fiber distance of the constituent fibers of the first fiber sheet is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less, and practically 5 μm or more.
＜１７＞
The absorbent sheet according to any one of <12> to <16>, wherein the fibers of the paper have a tendency to be oriented in one direction.
＜18＞
The absorbent sheet according to any one of <1> to <17>, wherein the orientation tendency of the fibers constituting the first fiber sheet and the orientation tendency of the fibers constituting the second fiber sheet are the same as each other.
＜19＞
The absorbent sheet according to any one of <1> to <18>, wherein the second fiber sheet is a hydrophilic nonwoven fabric.

＜20＞
The first fiber sheet and the second fiber sheet are joined together by an adhesive,
The absorbent sheet according to any one of <1> to <19>, comprising a portion where both fibrous sheets are directly bonded to each other by the adhesive without the water-absorbent polymer therebetween, and a portion where both fibrous sheets are bonded to each other by the adhesive via the water-absorbent polymer.
＜21＞
The absorbent sheet described in <20> above, wherein the portion where the two fiber sheets are directly bonded by the adhesive without the intermediation of the water-absorbent polymer is formed in the gap between the particles of the water-absorbent polymer in the region where the water-absorbent polymer is arranged.
＜22＞
The absorbent sheet according to item <20> or <21>, wherein in a region where both fiber sheets are directly bonded to each other by the adhesive without the intermediation of the water-absorbent polymer, the adhesive forms a columnar shape when viewed in cross section in the thickness direction of the sheet, directly bonding both fiber sheets to each other.
＜23＞
The absorbent sheet according to any one of <20> to <22>, wherein the portions where the two fiber sheets are directly bonded by the adhesive without the intermediation of the water-absorbent polymer are formed in a plurality of regular or irregular scattered dots in a plan view of the sheet.
＜24＞
The absorbent sheet according to any one of <20> to <23>, wherein a portion where both fiber sheets are directly bonded by the adhesive without the water-absorbent polymer therebetween maintains a state where both fiber sheets are directly bonded even after the water-absorbent polymer swells.

＜25＞
The absorbent sheet according to any one of <20> to <24>, wherein the adhesive is applied to each of a surface of the first fiber sheet facing the water-absorbent polymer and a surface of the second fiber sheet facing the water-absorbent polymer 13.
＜26＞
The absorbent sheet according to any one of <20> to <25>, wherein an area of the second fibrous sheet to which the adhesive is applied is larger than an area of the first fibrous sheet to which the adhesive is applied.
＜27＞
The absorbent sheet according to any one of <20> to <26>, wherein in a portion where the adhesive is applied, the basis weight of the adhesive in the first fiber sheet is higher than the basis weight of the adhesive in the second fiber sheet.
＜28＞
The absorbent sheet according to <27>, wherein the basis weight of the adhesive in the first fiber sheet is preferably 400 g/ ^m2 or less, more preferably 250 g/ ^m2 or less, even more preferably 100 g/ ^m2 or less, and is preferably 20 g/ ^m2 or more.
＜29＞
The absorbent sheet according to <27> or <28>, wherein the basis weight of the adhesive in the second fiber sheet is preferably 30 g/ ^m2 or less, more preferably 15 g/ ^m2 or less, even more preferably 10 g/ ^m2 or less, and is preferably ² g/m2 or more.

＜30＞
The absorbent sheet according to any one of <1> to <29> above, wherein the thickness, measured under an applied pressure of 1.7 kPa, is preferably 0.3 mm or more, more preferably 0.6 mm or more, and is preferably 4 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less.
＜31＞
An absorbent article comprising the absorbent sheet according to any one of <1> to <30>.
＜32＞
The absorbent article according to <31>, wherein the first fiber sheet in the absorbent sheet is disposed on the skin-facing side.
＜33＞
Applying an adhesive to at least one of the first and second fiber sheets;
A water-absorbing polymer is sprayed onto the surface of the fiber sheet to which the adhesive is applied;
The fiber sheets are overlapped so that the water-absorbent polymer is disposed between the two fiber sheets,
The overlapped fiber sheets are pressed, and then
and cutting each of the pressed fiber sheets.

REFERENCE SIGNS LIST 1 absorbent sheet 11 first fiber sheet 12 second fiber sheet 13 water-absorbent polymer

Claims (14)

An absorbent article comprising an absorbent sheet including a first fibrous sheet, a second fibrous sheet, and a water-absorbent polymer disposed between the fibrous sheets,
The absorbent article includes a top sheet, a moisture-permeable back sheet, and the absorbent sheet disposed between the top sheet and the back sheet,
When the Klemm water absorption height of each fiber sheet is measured in accordance with JIS P8141, the Klemm water absorption height of the first fiber sheet is higher than the Klemm water absorption height of the second fiber sheet,
An absorbent article, wherein the first fiber sheet of the absorbent sheet is disposed on the skin-facing side. 2. The absorbent article according to claim 1, wherein the first fibrous sheet has a Klemm water absorption height of 20 mm or more, and the second fibrous sheet has a Klemm water absorption height of 30 mm or less. 3. The absorbent article according to claim 1, wherein, when the airflow resistance of each fiber sheet is measured using a KES-F8 air permeability tester, the airflow resistance of the second fiber sheet is lower than the airflow resistance of the first fiber sheet. The first fiber sheet is paper having a crepe rate of 5% or more;
The absorbent article according to any one of claims 1 to 3, wherein the second fibrous sheet has a crepe rate of less than 1%. The absorbent article according to claim 4, wherein the distance between fibers of the paper is 30 μm or less. The absorbent article according to claim 4 or 5, wherein the paper fibers have a tendency to be oriented in one direction. 7. The absorbent article according to claim 1, wherein an orientation tendency of the fibers constituting the first fiber sheet and an orientation tendency of the fibers constituting the second fiber sheet are the same as each other. The absorbent article according to any one of claims 1 to 7, wherein the second fibrous sheet is a hydrophilic nonwoven fabric. The first fiber sheet and the second fiber sheet are joined together by an adhesive,
The absorbent article according to any one of claims 1 to 8, comprising a portion where both fibrous sheets are directly bonded by the adhesive without the water-absorbent polymer therebetween, and a portion where both fibrous sheets are bonded by the adhesive via the water- absorbent polymer . The absorbent article according to claim 9 , wherein an area of the adhesive applied to the second fibrous sheet is larger than an area of the adhesive applied to the first fibrous sheet. The absorbent article according to claim 9 or 10, wherein the basis weight of the adhesive in the first fibrous sheet is higher than the basis weight of the adhesive in the second fibrous sheet at the site where the adhesive is applied. The absorbent article according to any one of claims 1 to 11, wherein the thickness of the absorbent sheet measured under an applied pressure of 1.7 kPa is 0.3 mm or more and 4 mm or less. 13. The absorbent article according to claim 1, wherein a difference between the Klemm absorption height of the first fibrous sheet and the Klemm absorption height of the second fibrous sheet is 100 mm or more and 50 mm or less. A method for manufacturing an absorbent article according to any one of claims 1 to 13,
Applying an adhesive to at least one of the first and second fiber sheets;
A water-absorbing polymer is sprayed onto the surface of the fiber sheet to which the adhesive is applied;
The fiber sheets are overlapped so that the water-absorbent polymer is disposed between the two fiber sheets,
The overlapped fiber sheets are pressed, and then
Cutting each of the pressed fiber sheets to obtain an absorbent sheet;
A method for manufacturing an absorbent article, comprising disposing a first fiber sheet of the absorbent sheet on a skin-facing side of the absorbent article .

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