JP7636132B2 - Absorbent articles - Google Patents

Description

The present invention relates to an absorbent article.

Absorbent articles such as disposable diapers, absorbent pads (urine pads), and sanitary napkins are known. Absorbent articles are made of pulp or a super absorbent polymer (SAP) and have an absorbent body that absorbs liquids such as urine and body fluids. Patent Document 1 describes an absorbent article that has an upper absorbent body and a lower absorbent body, and has openings formed in these absorbent bodies.

International Publication No. 2016/114209

In absorbent articles, openings may be formed in the absorbent body to improve the diffusion of liquids. However, if an opening is formed that penetrates the upper and lower absorbent bodies, there is no absorbent body such as pulp or superabsorbent polymer in the opening, so the opening cannot absorb liquids such as urine, and there is a risk of the liquid leaking out.

Therefore, the present invention aims to provide an absorbent article that suppresses liquid leakage.

In order to solve the above problem, in the present invention, an SAP layer is disposed between the upper and lower absorbent layers.

In detail, the present invention relates to an absorbent article comprising: a liquid-permeable top sheet disposed on the skin-facing side; a liquid-impermeable back sheet disposed on the side opposite to the skin-facing side; an upper absorbent body between the back sheet and the top sheet and disposed on the top sheet side; a lower absorbent body between the back sheet and the top sheet and disposed on the back sheet side; a core wrap sheet wrapping the upper absorbent body and the lower absorbent body as a whole; an opening formed to penetrate the upper absorbent body in the thickness direction and extending in the longitudinal direction of the upper absorbent body with a width of 20 mm or more and 35 mm or less; and a plurality of superabsorbent polymer particles disposed between the upper absorbent body and the lower absorbent body along the longitudinal direction of the opening on both sides of the opening and within a range from 5 mm outside both ends of the opening to 10 mm from the ends of the upper absorbent body, the superabsorbent polymer having a basis weight of 140 g/m2 ^{or more} and 200 g/m2 or more. ² or less, the width of the SAP layer is 40 mm or more, and the longitudinal length of the SAP layer is included in the longitudinal length of the opening.

The above-mentioned absorbent article may further comprise a superabsorbent polymer contained in the upper absorbent body and the lower absorbent body, the superabsorbent polymer being 45% or more in the upper absorbent body and 55% or less in the lower absorbent body, assuming that the total basis weight ratio of the upper absorbent body and the lower absorbent body is 100%.

In the above-mentioned absorbent article, the basis weight of the superabsorbent polymer in the upper absorbent body is 50
The basis weight of the superabsorbent polymer in the lower absorbent body may be ⁰ g/m ² or more and 220 g/m ² or ^less .

The above absorbent article can prevent liquid leakage.

FIG. 1 is a plan view of an absorbent pad according to an embodiment. FIG. 2 is a cross-sectional view of an absorbent pad according to an embodiment. FIG. 3 is a table showing the results of the absorbency test of the absorbent pad. FIG. 4 is a table showing the results of the absorbency test of the absorbent pad.

The following describes an embodiment of the present invention. The embodiment described below is an example of an embodiment of the present invention, and does not limit the technical scope of the present invention to the following aspects.

<Embodiment>
FIG. 1 is a plan view of an absorbent pad (one example of an "absorbent article" in the present application) viewed from the skin-facing side. The absorbent pad 1 is used to absorb and retain liquids such as urine, and can be used alone or layered on the inside of a disposable diaper. The absorbent pad 1 is divided into a crotch region 5 covering the pubic area of the wearer, a front body region 3 located on the wearer's abdominal side, and a rear body region 7 located on the wearer's back side, as viewed in the longitudinal direction. The direction perpendicular to the longitudinal direction is the width direction (short direction) of the absorbent pad 1. In plan view, the absorbent pad 1 has the narrowest width in the crotch region 5, and the crotch region 5 has a narrowed gourd shape.

In the following, when the absorbent pad 1 is viewed in the longitudinal direction, the front body region 3 side will be referred to relatively as the "front", "front side" or "forward", the rear body region 7 side will be referred to relatively as the "rear", "rear side" or "rear", the left side relatively from the rear side to the front side will be referred to relatively as the "left", "left side" or "left side", and the right side relatively from the rear side to the front side will be referred to relatively as the "right", "right side" or "right side". The front-to-rear direction of the absorbent pad 1 is the longitudinal direction, and the left-to-right direction of the absorbent pad 1 is the width direction. The direction perpendicular to the front-to-rear and left-to-right directions is the thickness direction (height direction) of the absorbent pad 1.

As shown in FIG. 1, the absorbent pad 1 has a top sheet 11 arranged on the skin-facing side when worn. The top sheet 11 is the part (skin-facing side) that comes into contact with the wearer's skin when the absorbent pad 1 is worn, and is made of a liquid-permeable material that allows liquids such as urine to pass through. Specifically, the top sheet 11 is made of woven fabric, nonwoven fabric, porous film, etc. Note that the nonwoven fabric may be made of thermoplastic resin fibers such as polypropylene, polyethylene, polyester, nylon, etc. that have been hydrophilized, or may be an air-through nonwoven fabric, point-bonded nonwoven fabric, spun-bonded nonwoven fabric, melt-blown nonwoven fabric, etc.

The absorbent pad 1 also includes a back sheet 13 arranged on the opposite side of the skin-facing surface when worn. The back sheet 13 is the non-skin-facing surface (outer surface) opposite the skin-facing surface, and is made of a liquid-impermeable material that does not allow liquids such as urine to pass through. Specifically, a liquid-impermeable film made of polyethylene resin is used for the back sheet 13. Note that it is preferable to use a microporous polyethylene film with multiple fine holes of 0.1 to 4 μm formed therein for the back sheet 13 in order to obtain breathability to prevent stuffiness when worn while maintaining liquid impermeability.

The top sheet 11 and the back sheet 13 are joined to each other at their respective peripheral edges. In addition, an upper absorbent body 15 and a lower absorbent body 17 that absorb liquids such as urine are disposed between the top sheet 11 and the back sheet 13. The upper absorbent body 15 is disposed on the top sheet 11 side (skin facing side), and the lower absorbent body 17 is disposed on the back sheet 13 side (non-skin facing side). In a plan view, the upper absorbent body 15 has a gourd shape that is roughly the same as that of the absorbent pad 1. The lower absorbent body 17 is disposed below the upper absorbent body 15 when viewed from the top sheet 11 side. In a plan view, the lower absorbent body 17 has a rectangular shape whose long side is the longitudinal direction of the absorbent pad 1. In a plan view, the upper absorbent body 15 is formed larger than the lower absorbent body 17. The absorbent pad 1 is relatively large when liquid such as urine is excreted, and the urine can be rapidly absorbed by the upper absorbent body 15 arranged on the top sheet 11 side.

The upper absorbent layer 15 and the lower absorbent layer 17 are made of fluff pulp obtained by crushing fibrous materials such as coniferous trees, super absorbent polymers (SAP), hydrophilic sheets, or combinations of these. SAP absorbs about 100 to 1000 times its own weight in liquid. For example, granular SAP with a diameter of about 0.1 to 0.5 mm before absorbing liquid is used.

The absorbent pad 1 also has an opening 21 formed by penetrating the upper absorbent body 15 in the thickness direction. The opening 21 is formed to extend in the longitudinal direction of the upper absorbent body 15. The opening 21 is formed in approximately the center of the upper absorbent body 15 in the width direction. In a plan view, the opening 21 has a rectangular shape. The front end of the opening 21 is located in the middle of the front body region 3, and the rear end of the opening 21 is located in the rear of the crotch region 5. The opening 21 also has a constant width w1. For example, the width w1 is 20 mm or more and 35 mm or less. The length of the opening 21 is formed to be 155 mm or more and 350 mm or less. In this case, the absorbent pad 1 is suitable for an adult urine pad.

The opening 21 may be formed in correspondence with the position where the wearer's urethral opening comes into contact (urethral opening contact position) so that urine excreted by the wearer can easily flow in. The urethral opening contact position is defined as a position 60% of the longitudinal length of the upper absorbent body 15 forward from the rear end of the upper absorbent body 15. For example, if the longitudinal length of the upper absorbent body 15 is 500 mm, the urethral opening contact position is defined as a position 300 mm forward from the rear end of the upper absorbent body 15. In addition, if an R cut cut into an arc shape is formed at both left and right ends of the crotch region 5, the front-rear length of the R cut formation part is within 30 mm, and the narrowest part in the width direction of the upper absorbent body 15 is the part where the R cut is formed, the intersection of a straight line connecting the left and right ends of the narrowest part and a straight line passing through the center of the width direction of the upper absorbent body 15 may be defined as the urethral opening contact position.

In addition, the opening 21 may be formed in a polygonal or elliptical shape instead of a rectangular shape when viewed from above. In addition, both front and rear ends of the opening 21 may be formed in an arc shape.

Liquids such as urine excreted by the wearer are spread along the openings 21. Also, liquids such as urine excreted on the upper absorbent body 15 can be guided to the lower absorbent body 17 via the openings 21. In this way, the absorbent pad 1 according to this embodiment can absorb and retain liquids by both the upper absorbent body 15 and the lower absorbent body 17.

The absorbent pad 1 also has SAP layers 23L, 23R disposed between the upper absorbent body 15 and the lower absorbent body 17. The SAP layers 23L, 23R are formed by gathering together a plurality of particles of superabsorbent polymer (SAP). The SAP layers 23L, 23R contain a plurality of SAP particles and are capable of absorbing and retaining liquid introduced between the upper absorbent body 15 and the lower absorbent body 17. As shown in FIG. 1, the SAP layer 23L is disposed to the left of the opening 21, and the SAP layer 23R is disposed to the right of the opening 22.
1, SAP layer 23R is disposed to the right of opening 21. Thus, SAP layers 23L, 23R are disposed on both sides of opening 21 along the longitudinal direction of opening 21. Moreover, SAP layers 23L, 23R are formed in a rectangular shape in plan view. Note that SAP layers 23L, 23R may be formed in a polygonal shape or an elliptical shape other than a rectangular shape in plan view. By providing SAP layers, absorbent pad 1 can increase the overall amount of liquid absorbed.

The SAP layer 23L is arranged from w2 mm outside the left end of the opening 21 to w3 mm inside the left end of the upper absorbent body 15. Similarly, the SAP layer 23R is arranged from w2 mm outside the right end of the opening 21 to w3 mm inside the right end of the upper absorbent body 15. In this way, the SAP layers 23L, 23R are arranged from w2 mm outside both ends of the opening 21 to w3 mm inside the width direction ends of the upper absorbent body 15. w2 mm is, for example, 5 mm, and w3 mm is, for example, 10 mm. The SAP layers 23L, 23R are longer than the opening 21, and the longitudinal length of the opening 21 is included in the longitudinal length of the SAP layers 23L, 23R.

In this embodiment, the SAP layers 23L and 23R are arranged on both sides of the opening 21 along the longitudinal direction of the opening 21, and within a range of 5 mm outside both ends of the opening 21 and 10 mm from the end of the upper absorbent body 15, and the width of the SAP layers 23L and 23R is 40 mm or more.

As described above, the absorbent pad 1 according to this embodiment includes an upper absorbent body 15, a lower absorbent body 17, an opening 21, and SAP layers 23L and 23R. The longitudinal directions of the upper absorbent body 15, the lower absorbent body 17, the opening 21, and the SAP layers 23L and 23R are aligned. Furthermore, the opening 21 and the SAP layers 23L and 23R are arranged approximately parallel to each other.

In addition, the absorbent pad 1 has three-dimensional gathers (not shown) arranged along the left and right edges of the lower absorbent body 17 when viewed from the skin-facing side. The three-dimensional gathers are joined to the top sheet 11 to prevent side leakage of liquid.

Figure 2 is a cross-sectional view of the absorbent pad 1 shown in Figure 1 taken along line A-A. Note that in Figure 2, in order to make each component of the absorbent pad 1 easier to understand, gaps are shown between each component, but in reality, there are almost no gaps between each component.

As shown in FIG. 2, the upper absorbent body 15 and the lower absorbent body 17 are entirely wrapped by the core wrap sheets 31 and 33. The core wrap sheets 31 and 33 are provided to diffuse the liquid that has permeated the top sheet 11 throughout the upper absorbent body 15 and the lower absorbent body 17. The core wrap sheet 31 is disposed between the top sheet 11 and the upper absorbent body 15, and covers the upper absorbent body 15 from the top sheet 11 side. The core wrap sheet 33 covers the back sheet 13 side surface of the lower absorbent body 17, the sides of the upper absorbent body 15 and the lower absorbent body 17, and a part of the top sheet 11 side surface of the upper absorbent body 15, and is joined to the core wrap sheet 31 on the top sheet 11 side. In this way, the core wrap sheets 31 and 33 are joined to each other to form an integrated unit, and entirely wrap the upper absorbent body 15 and the lower absorbent body 17. The core wrap sheets 31 and 33 are made of, for example, thin paper such as tissue paper or nonwoven fabric. The core wrap sheets 31 and 33 may be integrally formed.

The SAP layers 23L, 23R are formed by scattering SAP particles on the lower absorbent body 17. In addition, the SAP layers 23L, 23R are sandwiched between the upper absorbent body 15 and the lower absorbent body 17. For this reason, even if the absorbent pad 1 moves due to the wearer's actions, the SAP particles contained in the SAP layers 23L, 23R can be prevented from moving below the opening 21 or falling out of the lower absorbent body 17.

As described above, the absorbent pad 1 according to this embodiment has a structure in which, viewed in the thickness direction from the skin-facing surface side, the top sheet 11, the core wrap sheet 31, a portion of the core wrap sheet 33, the upper absorbent body 15, the SAP layers 23L and 23R, the lower absorbent body 17, a portion of the core wrap sheet 33, and the back sheet 13 are laminated in this order. In addition, the peripheral portions of the top sheet 11 and the back sheet 13 are joined to each other, so that the core wrap sheets 31 and 33, the upper absorbent body 15, the SAP layers 23L and 23R, and the lower absorbent body 17 are surrounded and sealed by the top sheet 11 and the back sheet 13.

In the absorbent pad described in the above Patent Document 1, a through-type opening is formed that penetrates the upper absorbent body and the lower absorbent body in the thickness direction. When the through-type opening is viewed in the thickness direction, there is no absorbent such as fluff pulp or SAP, so liquids such as urine cannot be absorbed through the opening. On the other hand, in the absorbent pad 1 according to this embodiment, an opening 21 is formed in the upper absorbent body 15, and no opening is formed in the lower absorbent body 17. Therefore, in the absorbent pad 1 according to this embodiment, a part of the lower absorbent body 17 faces the opening end below the opening 21 (on the lower absorbent body 17 side) when viewed in the thickness direction, so that the liquid that flows into the opening 21 can be absorbed by the lower absorbent body 17. In addition, if the dimensions of each component of the absorbent pad described in the above Patent Document 1 and the absorbent pad 1 according to this embodiment are the same, the absorbent pad described in the above Patent Document 1 has a smaller absorbent body volume by the volume of the opening formed in the lower absorbent body compared to the absorbent pad 1 according to this embodiment. For this reason, when the absorbent pad described in Patent Document 1 is worn and a large amount of urine is excreted, there is a risk that the lower absorbent body will not be able to absorb enough, resulting in urine leakage. However, the absorbent pad 1 according to this embodiment does not have openings in the lower absorbent body 17, so the volume of the lower absorbent body 17 is not reduced, and urine leakage can be suppressed without causing an insufficient absorption capacity in the lower absorbent body 17 even when a large amount of urine is excreted.

Example 1
Next, a description will be given of the absorbent pad 1 according to Example 1 of this embodiment. The absorbent pad 1 according to this example is characterized by the basis weight ratio of SAP in the upper absorbent body 15 and the lower absorbent body 17.

In the absorbent pad 1 according to this embodiment, the upper absorbent body 15 and the lower absorbent body 17 are made of, for example, fluff pulp. The upper absorbent body 15 contains SAP. The lower absorbent body 17 may contain SAP. If the total SAP weight ratio in the upper absorbent body 15 and the lower absorbent body 17 is 100%, the SAP weight ratio in the upper absorbent body 15 is 45% or more and the SAP weight ratio in the lower absorbent body 17 is 55% or less. If the lower absorbent body 17 does not contain SAP, the SAP weight ratio in the upper absorbent body 15 is 100% and the SAP weight ratio in the lower absorbent body 17 is 0%.

The basis weight of the SAP in the upper absorbent body 15 is 50 g/ ^m2 or more and 180 g/ ^m2 or less, and the basis weight of the SAP in the lower absorbent body 17 is 0 g/ ^m2 or more and 220 g/ ^m2 or less. The lower limit of the basis weight of the SAP in the lower absorbent body 17 is 0 g/ ^m2 , and when the basis weight is 0 g/ ^m2, no SAP is contained.

In the absorbent pad 1 according to this embodiment, the upper absorbent body 15 containing SAP quickly absorbs liquids such as urine, thereby preventing the top sheet 11 from absorbing liquids and preventing liquids from pooling on the surface of the top sheet 11, and preventing the wearer from feeling uncomfortable. The lower absorbent body 17 absorbs liquids that the upper absorbent body 15 was not able to absorb and liquids that have diffused through the openings 21. The absorbent pad 1 according to this embodiment can suppress leakage of liquids by absorbing and retaining liquids with the upper absorbent body 15 and the lower absorbent body 17.

In general, when an upper absorbent body and a lower absorbent body are provided, it is considered to increase the absorption capacity of the lower absorbent body to suppress liquid leakage to the back sheet side. To increase the absorption capacity of the absorbent body, for example, the basis weight ratio or basis weight of SAP in the lower absorbent body is increased. However, when an opening is formed in the upper absorbent body and an opening is not formed in the lower absorbent body, if the basis weight ratio of SAP in the lower absorbent body is increased more than necessary, the lower absorbent body may absorb a large amount of liquid and swell too much, which may block the opening. For example, if the lower absorbent body absorbs urine and swells during the first urination, and blocks the opening, urine cannot be diffused through the opening during the second and subsequent urinations, which may cause urine leakage. On the other hand, in the absorbent pad 1 according to this embodiment, when the sum of the basis weight ratios of SAP in the upper absorbent body 15 and the lower absorbent body 17 is 100%, the basis weight ratio of SAP in the upper absorbent body 15 is 45% or more, and the basis weight ratio in the lower absorbent body 17 is 55% or less. This prevents the lower absorbent body 17 from swelling to the extent that it blocks the opening 21 when absorbing liquid, thereby preventing the opening 21 from being blocked. The absorbent pad 1 according to this embodiment prevents the lower absorbent body 17 from blocking the opening 21 when absorbing liquid such as urine, and by diffusing urine through the opening during the second and subsequent urinations, it is possible to suppress urine leakage.

Next, a urine injection test (hereinafter referred to as "the test") for an absorbent pad will be described. In this test, the optimum range of the SAP basis weight ratio in the upper absorbent body 15 and the lower absorbent body 17 that can suppress liquid leakage is derived. Note that if SAP layers 23L, 23R are provided in the absorbent pad, the absorption amount of the SAP layers 23L, 23R will affect the test results, making it impossible to derive the optimum range of the SAP basis weight ratio. For this reason, an absorbent pad that does not have SAP layers 23L, 23R was created and this test was conducted.

The materials prepared for this test were a test plate (16 cm x 16 cm, made of iron, 10 mm thick), artificial urine, and filter paper (80 mm x 8 mm). The test plate had a circular hole (diameter 40 mm) formed in the center.

The absorbent pad is then spread out without any wrinkles and secured in place. Packing tape or hook tape is used for securing. The absorbent pad is secured so that the back area faces the worker.

The test plate is placed on the absorbent pad so that the center of the hole in the test plate is located at the center of the longitudinal direction of the opening of the absorbent pad. Next, 150 ml of artificial urine is prepared. The artificial urine was prepared by dissolving 20 g of urea, 8 g of sodium chloride, 0.8 g of magnesium sulfate heptahydrate, and 0.3 g of calcium chloride dihydrate in 1000 mL of distilled water. 150 ml of the prepared artificial urine is poured into the hole in the test plate. When the absorbent pad has absorbed all of the artificial urine, the test plate is removed from the absorbent pad. The absorbent pad has absorbed all of the artificial urine when all of the artificial urine poured into the absorbent pad has disappeared from the top sheet. The time from the start of the injection of the artificial urine to the time when all of the artificial urine has been absorbed was evaluated as the absorption rate (seconds). 11 minutes after the first injection of artificial urine into the absorbent pad, the test plate is placed on the absorbent pad in the same manner as above, and 11 minutes after the first injection of artificial urine, 140 ml of artificial urine is injected into the absorbent pad again in the same manner as above. This process is repeated one more time. In this way, a total of 430 ml of artificial urine is injected into the absorbent pad.

The results of this test are shown in a table in Figure 3. In this test, the SAP basis weight ratio in the upper and lower absorbent bodies was changed in 5% increments between 0 and 100% (21 pieces), and the width of the opening was changed in 5 mm increments between 15 mm and 40 mm (6 pieces), to create a total of 121 absorbent pads.

The "Leakage Suppression" column in the table in Figure 3 indicates whether the absorbent pad was able to suppress leakage of liquid. "◎" and "◯" in the column indicate results in which leakage was suppressed. More specifically, "◎" in the column indicates results in which the lower absorbent body did not fill the opening at all, and leakage was suppressed without a decrease in absorption rate. "◯" in the column indicates results in which the lower absorbent body hardly filled the opening, and leakage was suppressed without a decrease in absorption rate. Also, "△", "×1", "×2", and "×3" in the column indicate results in which leakage could not be suppressed. More specifically, "×1" in the column indicates results in which the opening was filled due to the swelling of the lower absorbent body, causing a decrease in absorption rate, and leakage could not be suppressed. "×2" in the column indicates results in which the opening was not filled, but the width of the opening was too narrow, so it took time for the artificial urine to diffuse through the opening, and the artificial urine was absorbed before it was completely diffused, and the opening could not perform its function of diffusing the artificial urine, causing the absorption rate to decrease and leakage could not be suppressed. The "x3" in the relevant column indicates that the opening was not filled, but the opening was too wide, so the artificial urine was absorbed before it could fully diffuse in the longitudinal direction of the opening, and the opening was unable to function to diffuse the artificial urine, resulting in failure to prevent leakage.

As can be seen from the table in Figure 3, when the opening width is 20 mm, it is preferable that the SAP basis weight ratio in the upper absorbent layer is greater than 30% and the SAP basis weight ratio in the lower absorbent layer is greater than 70%, it is even more preferable that the SAP basis weight ratio in the upper absorbent layer is greater than 35% and the SAP basis weight ratio in the lower absorbent layer is greater than 65%, and leakage can be suppressed by setting the SAP basis weight ratio in the upper absorbent layer to 45% or more and the SAP basis weight ratio in the lower absorbent layer to 55% or more. Similarly, when the opening width is 25 mm, it is preferable that the SAP basis weight ratio in the upper absorbent body is greater than 25% and the SAP basis weight ratio in the lower absorbent body is greater than 75%, it is even more preferable that the SAP basis weight ratio in the upper absorbent body is greater than 30% and the SAP basis weight ratio in the lower absorbent body is greater than 70%, it is even more preferable that the SAP basis weight ratio in the upper absorbent body is greater than 35% and the SAP basis weight ratio in the lower absorbent body is greater than 65%, and leakage can be suppressed by setting the SAP basis weight ratio in the upper absorbent body to 45% or more and the SAP basis weight ratio in the lower absorbent body to 55% or more. Similarly, when the opening width is 30 mm or 35 mm, it is preferable that the SAP weight ratio in the upper absorbent body is greater than 20% and the SAP weight ratio in the lower absorbent body is greater than 80%, it is even more preferable that the SAP weight ratio in the upper absorbent body is greater than 25% and the SAP weight ratio in the lower absorbent body is greater than 75%, it is even more preferable that the SAP weight ratio in the upper absorbent body is greater than 30% and the SAP weight ratio in the lower absorbent body is greater than 70%, it is even more preferable that the SAP weight ratio in the upper absorbent body is greater than 35% and the SAP weight ratio in the lower absorbent body is greater than 65%, and it is possible to suppress leakage by setting the SAP weight ratio in the upper absorbent body to 45% or more and the SAP weight ratio in the lower absorbent body to 55% or more.

Thus, when the opening width is 20-35mm, it is preferable that the SAP weight ratio in the upper absorbent layer is greater than 30% and the SAP weight ratio in the lower absorbent layer is greater than 70%, and it is even more preferable that the SAP weight ratio in the upper absorbent layer is greater than 35% and the SAP weight ratio in the lower absorbent layer is greater than 65%. It is possible to suppress leakage by setting the SAP weight ratio in the upper absorbent layer to 45% or more and the SAP weight ratio in the lower absorbent layer to 55% or more. It is noted that when the SAP weight ratio in the upper absorbent layer is 95% or 100% and the SAP weight ratio in the lower absorbent layer is 5% or 0%, leakage suppression was most successful, as shown by the result of "◎".

On the other hand, when the opening width was 15 mm or 40 mm, leakage could not be suppressed. When the opening width was 15 mm and the SAP basis ratio in the upper absorbent was 45% or more and the SAP basis ratio in the lower absorbent was 55% or less, the results of leakage suppression were as shown by "x2", as the opening width was too narrow and it took a long time for the artificial urine to diffuse through the opening, and the artificial urine was absorbed before it was completely diffused, and the opening could not perform its function of diffusing the artificial urine, so the absorption rate decreased and leakage could not be suppressed. When the opening width was 40 mm and the SAP basis ratio in the upper absorbent was 30% or more and the SAP basis ratio in the lower absorbent was 70% or less, the results of leakage suppression were as shown by "x3", as the opening was not filled, but the opening width was too wide and the artificial urine was absorbed before it was completely diffused in the longitudinal direction of the opening, and the opening could not perform its function of diffusing the artificial urine, so leakage could not be suppressed. For this reason, the width of the opening 21 is preferably greater than 15 mm and less than 40 mm, and more preferably greater than or equal to 20 mm and less than or equal to 35 mm.

Thus, as shown in Figure 3, leakage could be suppressed by setting the SAP basis ratio to 45% or more in the upper absorbent layer 15 and 55% or less in the lower absorbent layer 17.

In addition, since SAP exerts a function of retaining liquid in the absorbent, if the basis weight of SAP in the upper absorbent is too small, the upper absorbent will not be able to retain the liquid once absorbed, resulting in backflow, and conversely, if the basis weight of SAP in the upper absorbent is too large, gel blocks will be generated when absorbing liquid, resulting in a decrease in absorption speed. Furthermore, if the basis weight of SAP in the lower absorbent is too large, the lower absorbent will absorb too much liquid and swell, filling up the openings. For this reason, the basis weight of SAP in the upper absorbent is in the range of 50 g/ ^m2 or more and 180 g/ ^m2 or less, and the basis weight of SAP in the lower absorbent is in the range of 0 g/ ^m2 or more and 220 g/ ^m2 or less. Even within this basis weight range, leakage can be suppressed as long as the above-mentioned SAP basis weight ratio is within the range. In the experimental examples shown in FIG. 3, in which leakage was suppressed, the SAP weight in the upper absorbent body was 90 g/m ² to 170 g/m ² , and the SAP weight in the lower absorbent body was 0 g/m ² to 120 g/m ² .

The absorbent pad 1 according to this embodiment includes SAP which is included in the upper absorbent body 15 and the lower absorbent body 17, and when the total basis weight ratio of the upper absorbent body 15 and the lower absorbent body 17 is taken as 100%, the SAP is 45% or more in the upper absorbent body 15 and 55% or less in the lower absorbent body 17. In the absorbent pad 1 according to this embodiment, the basis weight of the SAP in the upper absorbent body ¹⁵ is 50 g/m2 or more and 180 g/ ^m2 or less, and the basis weight of the SAP in the lower absorbent body 17 is 0 g/ ^m2 or more and 220 g/ ^m2 or less. According to the absorbent pad 1 according to this embodiment, the openings 21 can diffuse liquid, and leakage of liquid can be suppressed.

In the case of the result of "◎", the absorption speed in the test in which artificial urine was injected three times was 20 seconds or less. In the case of the result of "◯", the absorption speed in the test in which artificial urine was injected three times was 21 seconds or more and 25 seconds or less. In the case of the result of "△", the absorption speed in the test in which artificial urine was injected three times was 26 seconds or more and 59 seconds or less. In the result of "×1", the absorption speed in the test in which artificial urine was injected three times was 60 seconds or more. In the results of "×2" and "×3", the absorption speed was not evaluated because the opening was not able to diffuse the artificial urine. If the absorption speed is 26 seconds or more, the unabsorbed artificial urine will accumulate on the top sheet, and there is a risk of side leakage from the gap between the three-dimensional gathers and the skin, which is not preferable. According to the absorbent pad 1 of this embodiment, the liquid leakage can be suppressed without decreasing the liquid absorption speed.

Example 2
Next, an absorbent pad 1 according to Example 2 of this embodiment will be described. The absorbent pad 1 according to this Example is characterized by the basis weight of SAP in the SAP layers 23L and 23R.

In the absorbent pad 1 of this embodiment, the basis weight of each of the SAP layers 23L, 23R is, for example, 140 to 200 g/ ^m2 , the length (length in the front-to-rear direction) of each of the SAP layers 23L, 23R is 470 to 555 mm, the width of each of the SAP layers 23L, 23R is 40 mm or more and preferably 40 to 45 mm, the area of each of the SAP layers 23L, 23R is 0.018 to 0.025 ^m2 , and the amount of SAP dispersed in each of the SAP layers 23L, 23R is 6 to 10 g.

The absorbent pad 1 according to this embodiment can guide a portion of liquid such as urine excreted by the wearer downward through the opening 21 to the lower side of the upper absorbent body 15, where it can be absorbed by the SAP layers 23L, 23R. As a result, even if a large amount of liquid such as urine is excreted at once, the absorbent pad 1 can absorb the liquid with the SAP layers 23L, 23R, thereby preventing leakage of the liquid.

When the SAP particles absorb liquid, the SAP layers 23L, 23R swell overall and become thicker. As the thickness of the SAP layers 23L, 23R arranged between the upper absorbent 15 and the lower absorbent 17 increases, the SAP layers 23L, 23R lift the upper absorbent 15, and the height of the region 24 between the SAP layers 23L, 23R (the region below the opening 21) also increases, and the opening end of the opening 21 on the lower absorbent 17 side can be extended by the thickness of the SAP layer to increase the height of the opening 21. This prevents the lower absorbent 17 from blocking the opening 21 even if the lower absorbent absorbs urine and swells, and by diffusing the urine through the opening 21, leakage of liquids such as urine can be suppressed.

In addition, in the absorbent pad 1 according to this embodiment, the longitudinal length of the opening 21 is included within the longitudinal length of the SAP layers 23L, 23R. This allows the SAP layers 23L, 23R to absorb liquid and increase in thickness, thereby increasing the overall height of the opening 21, preventing a portion of the opening 21 from being blocked, and diffusing urine through the opening 21 to suppress leakage of liquids such as urine.

Next, a test similar to that in Example 1 was carried out. Figure 4 is a table showing the results of a urine injection test of absorbent pads. In this test, the SAP basis weight (g/ ^m2 ) in the SAP layer was changed in increments of 20 (g/ ^m2 )% between 0 and 240 (13 pads), and the width of the opening was changed in increments of 5 mm between 15 mm and 40 mm (6 pads), to produce a total of 78 absorbent pads.

The "Leakage Suppression" column in the table of FIG. 4 indicates whether the absorbent pad was able to suppress liquid leakage. "◎" and "◯" in the column indicate results in which leakage was suppressed. More specifically, "◎" in the column indicates results in which the SAP layer swells, increasing the height of the region between the SAP layers on both sides (region 24 shown in FIG. 2 ), and the lower absorbent body does not fill the opening at all, so that leakage was suppressed without a decrease in absorption rate. "◯" in the column indicates results in which the SAP layer swells a little, increasing the height of the region between the SAP layers on both sides, and the lower absorbent body does not fill the opening at all, so that leakage was suppressed without a decrease in absorption rate.

The "△", "x1", "x2", "x3", and "x4" in the column indicate results in which leakage could not be suppressed. More specifically, "△" indicates a result in which the SAP layer did not expand much, so the height of the region between the SAP layers on both sides did not increase, and the lower absorbent body filled the opening a little, so that the absorption rate decreased and leakage could not be suppressed. "x1" indicates a result in which the SAP layer did not expand much, so the height of the region between the SAP layers on both sides did not increase, and the lower absorbent body filled the opening, so that the absorption rate decreased and leakage could not be suppressed. "x2" in the column indicates a result in which the opening was not filled, but the width of the opening was too narrow, so that it took time for the artificial urine to diffuse through the opening, and the artificial urine was absorbed before it was completely diffused, so that leakage could not be suppressed due to the decrease in absorption rate. "x3" in the column indicates a result in which the opening was not filled, but the width of the opening was too wide, so that the artificial urine was absorbed before it was completely diffused in the longitudinal direction of the opening, so that the opening could not perform its function of diffusing the artificial urine, so that leakage could not be suppressed. The "x4" in the relevant column indicates that the SAP basis weight in the SAP layer was too large (too many SAP particles), causing the expanded SAP layer to overflow into the opening, filling the opening with SAP, reducing the absorption rate and making it impossible to prevent leakage.

As can be seen from the table in Figure 4, when the opening width is 15 mm, the basis weight of SAP in the SAP layer is preferably greater than 80 g/ ^m2 , more preferably greater than 100 g/ ^m2 , even more preferably greater than 120 g/ ^m2 , and 140 g/ ^m2 or more to suppress leakage. Similarly, when the opening width is 20 mm, the basis weight of SAP in the SAP layer is preferably greater than 60 g/ ^m2 , more preferably greater than 80 g/ ^m2 , even more preferably greater than 100 g/ ^m2 , even more preferably greater than 120 g/ ^m2 , and 140 g/ ^m2 or more to suppress leakage. Similarly, when the opening width is 25 mm or 30 mm, the basis weight of SAP in the SAP layer is preferably greater than 40 g/ ^m2 , more preferably greater than 60 g/ ^m2 , more preferably greater than 80 g/ ^m2 , more preferably greater than 100 g/ ^m2 , more preferably greater than 120 g/ ^m2 , and more preferably 140 g/ ^m2 or more, which can suppress leakage. Similarly, when the opening width is 35 mm, the basis weight of SAP in the SAP layer is preferably greater than 20 g/ ^m2 , more preferably greater than 40 g/ ^m2 , more preferably greater than 60 g/ ^m2 , more preferably greater than 80 g/ ^m2 , more preferably greater than 100 g/ ^m2 , more preferably greater than 120 g/ ^m2 , and more preferably 140 g/ ^m2 or more, which can suppress leakage.

Thus, when the opening width is 15 to 35 mm, the basis weight of the SAP in the SAP layer is preferably greater than 80 g/ ^m2 , more preferably greater than 100 g/ ^m2 , and even more preferably greater than 120 g/ ^m2 , and leakage could be suppressed when the basis weight was 140 g/ ^m2 or more and 200 g/ ^m2 or less. As shown by "◎" in the column for the basis weight of the SAP of 200 g/ ^m2 , leakage was most suppressed when the basis weight of the SAP was 200 g/ ^m2 .

On the other hand, when the opening width was 40 mm, leakage could not be suppressed regardless of the SAP basis weight in the SAP layer. This is because, as most results when the opening width was 40 mm were "x3", the opening width was too wide and the artificial urine was absorbed before it could completely diffuse in the longitudinal direction of the opening, so the opening could not perform its function of diffusing the artificial urine and leakage could not be suppressed. For this reason, the width of the opening 21 is preferably less than 40 mm, and preferably 35 mm or less.

As shown in Fig. 4, when the basis weight of SAP in the SAP layer is 140 to 200 (g/ ^m2 ), leakage can be suppressed. In the absorbent pad 1 according to this embodiment, the basis weight of SAP in the SAP layer is 140 g/ ^m2 or more and 200 g/ ^m2 or less. According to the absorbent pad 1 according to this embodiment, the openings 21 can diffuse the liquid, and leakage of the liquid can be suppressed.

In the case of the result of "◎", the absorption speed in the test in which artificial urine was injected three times was 20 seconds or less. In the case of the result of "◯", the absorption speed in the test in which artificial urine was injected three times was 21 seconds or more and 25 seconds or less. In the case of the result of "△", the absorption speed in the test in which artificial urine was injected three times was 26 seconds or more and 59 seconds or less. In the result of "×1", the absorption speed in the test in which artificial urine was injected three times was 60 seconds or more. In the results of "×2", "×3", and "×4", the absorption speed was not evaluated. If the absorption speed is 26 seconds or more, the unabsorbed artificial urine may accumulate on the top sheet, which may cause side leakage from the gap between the three-dimensional gathers and the skin, which is not preferable. According to the absorbent pad 1 of this embodiment, the liquid leakage can be suppressed without decreasing the liquid absorption speed.

In the above embodiment and examples, the absorbent pad 1 is exemplified, but the above configuration can also be applied to other types of absorbent articles. Examples of absorbent articles to which the above configuration can be applied include various types of absorbent articles with gathers, such as pants-type disposable diapers, tape-type disposable diapers, urine pads, and light incontinence pads, as well as flat absorbent articles without gathers.

1. Absorbent pad: 3. Front body area: 5. Crotch area: 7. Back body area: 11. Top sheet: 13. Back sheet: 15. Upper absorbent body: 17. Lower absorbent body: 21. Opening: 23L. SAP layer: 23R. SAP layer: 31. Core wrap sheet: 33. Core wrap sheet

Claims (1)

A liquid-permeable top sheet disposed on the skin-facing side;
A liquid-impermeable back sheet disposed on the opposite side of the skin-facing surface;
an upper absorbent body disposed between the back sheet and the top sheet on the side of the top sheet;
a lower absorbent body disposed between the back sheet and the top sheet on the back sheet side;
a core wrap sheet that wraps the entire upper absorbent body and the entire lower absorbent body;
an opening formed through the upper absorbent body in a thickness direction, having a width of 15 mm or more and 35 mm or less, and extending in a longitudinal direction of the upper absorbent body;
an SAP layer between the upper absorbent body and the lower absorbent body, disposed on both sides of the opening along the longitudinal direction of the opening and within a range of 5 mm outside both ends of the opening and 10 mm from the end of the upper absorbent body, the SAP layer containing a plurality of superabsorbent polymer particles, the superabsorbent polymer having a basis weight of 140 g/ ^m2 or more and 200 g/ ^m2 or less;
Equipped with
The lower absorbent body does not have an opening that overlaps with the opening of the upper absorbent body,
the width of the SAP layer is greater than or equal to 40 mm and less than or equal to 45 mm;
a longitudinal length of the SAP layer includes a longitudinal length of the opening;
Absorbent articles.

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