JP2013255556A - Absorber and absorbent article - Google Patents

Abstract

To provide an absorbent body and an absorbent article capable of achieving both a high absorption amount and a low liquid remaining amount in repeated absorption of excreted liquid.
An absorbent body 10 of the present invention is an absorbent body having hydrophilic fibers and a water-absorbing polymer, and has a recess 11 having a depth of 20% to 100% of the thickness of the absorbent body. The mass ratio represented by [mass of hydrophilic fiber] / [mass of water-absorbing polymer] in the absorbent body 10 is 1/5 or more and 1 / 0.01 or less, and the water-absorbing polymer has a swelling ratio of 60% or less. The flow rate of 40 g of artificial urine under 2 kPa pressure is 100 g / min or less.
[Selection] Figure 4

Description

  The present invention relates to an absorbent body and an absorbent article.

  In absorbent articles, such as a disposable diaper, the material and structure of each member were improved and the function and the feeling of wear have been improved. Absorbers used for absorbent articles have also been developed with the intention of such improvements, and various types of improved functionalities have been proposed in accordance with usage conditions and types of articles.

  Patent Document 1 includes an absorbent body that includes a water-absorbing polymer having an absorption amount under pressure at 2 kPa of 20 g / g or more and a liquid passing rate under pressure at 2 kPa of less than 50 ml / min. An absorbent article and an absorbent article in which a plurality of regions where the water-absorbing polymer is disposed are formed to be spaced apart from each other in the planar direction of the absorbent body are disclosed. By arranging a plurality of water-absorbing polymers having specific physical properties so as to be spaced apart from each other in the plane direction, the leak-proof effect and / or air permeability is enhanced.

In Patent Document 2, a water-absorbing resin having a liquid permeability of 1 ml / min or more under pressure of 20 g / cm ² is used for the absorbent article, and the water absorption is 32 ± 5 ml / g. It is described that a water-absorbing resin in the range is used.

JP 2009-72421 A JP 2001-239159 A

However, although the absorbent article disclosed in Patent Document 1 has a very high absorption rate in absorption by repeated excretion, there is room for improvement from the viewpoint of leakage prevention effect (high absorption amount and low liquid return amount). It was.
In addition, since the absorbent body constituting the absorbent article disclosed in Patent Document 2 is not provided with a plurality of recesses, the water-absorbent resin gel-blocks during repeated excretion, and leak-proof effect (high absorption amount or Low liquid return amount) was insufficient.

  The problem of the present invention is that it has a good absorption performance for liquids that are repeatedly supplied over a long period of use, such as aqueous liquids, or body fluids such as urine, menstrual blood or sweat. An object of the present invention is to provide an absorbent body and an absorbent article that can achieve both a high absorption amount and a low liquid remaining amount.

The present invention is an absorbent body having hydrophilic fibers and a water-absorbing polymer, and an absorbent body having a recess having a depth of 20% or more and 100% or less of the thickness of the absorbent body. The mass ratio represented by [mass of the conductive fiber] / [mass of the water absorbent polymer] is 1/5 or more and 1 / 0.01 or less,
The water-absorbing polymer is an absorbent having a swelling ratio of 60% or less and a passing rate of 40 g of artificial urine having the following composition under a pressure of 2 kPa of 100 g / min or less.
Artificial urine composition: 1.94% urea, 0.80% sodium chloride, 0.06% calcium chloride, 0.11% magnesium sulfate, 0.085% ammonium dihydrogen phosphate, 0.015% diammonium hydrogen phosphate , 96.99% ion-exchanged water.

  The present invention also provides a liquid-permeable top sheet disposed on the skin contact surface side, a liquid-impermeable back sheet disposed on the non-skin contact surface side, and an absorber disposed between both sheets. And an absorbent article using the above-mentioned absorber of the present invention for the absorber.

  The absorbent body and absorbent article of the present invention use a water-absorbing polymer with weak cross-linking that causes gel blocking at a low swelling ratio in the absorbent body having a concave portion, so that the water-absorbing portion in which the concave portion is swollen in repeated excretion. Until it is filled with polymer, it spreads the liquid while suppressing gel blocking and exhibits high absorbency, and when filled with a water-absorbing polymer with swollen recesses, it causes gel blocking and does not allow pore water to permeate the skin side and has low liquid return. Excellent effects such as exhibiting

1A and 1B are diagrams showing an embodiment of an absorbent body according to the present invention, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view. FIG. 2 is a conceptual diagram showing the relationship between the swelling ratio of the water-absorbing polymer and the liquid passing speed under a pressure of 2 kPa. Drawing 3 is an explanatory view of the operation effect of the absorber of the present invention, and an absorptive article. FIG. 4 is a plan view illustrating a disposable diaper that is an embodiment of the absorbent article of the present invention with a part thereof broken. FIG. 5 is a partially broken plan view (corresponding to FIG. 4) showing another embodiment of the absorbent body and absorbent article of the present invention. FIG. 6 is an explanatory diagram of a method for measuring a liquid passing rate under a pressure of 2 kPa. FIG. 7 is an explanatory diagram of the configuration of the absorber used in Examples and Comparative Examples.

Hereinafter, an absorber and an absorptive article concerning the present invention are explained based on the preferred embodiment, referring to drawings.
As shown in FIG. 1, an absorbent body 10 according to an embodiment of the present invention includes a hydrophilic fiber 21 such as pulp fiber and a water absorbent polymer 22, and [mass of hydrophilic fiber] / [water absorbent polymer]. The mass ratio represented by [mass of] is 1/5 or more, preferably 1/3 or more, more preferably 1/2 or more, and 1 / 0.01 or less, preferably 1 / 0.1 or less. Preferably it is 1 / 0.5 or less, more specifically 1/5 or more and 1 / 0.01 or less, preferably 1/3 or more and 1 / 0.1 or less, more preferably 1/2 or more. 1 / 0.5 or less. In the absorbent body 10, for example, a water-absorbing polymer 22 is dispersed in a molded body of hydrophilic fibers 21 formed by stacking. Alternatively, the water-absorbing polymer 22 may be dispersed between the layers of the hydrophilic fibers 21 formed by stacking the fibers.
From the viewpoint of supporting the water-absorbing polymer 22 in the molded body of the hydrophilic fiber 21 or between the layers of the hydrophilic fiber 21, the mass ratio is preferably equal to or higher than the lower limit value of the above ranges, and the absorption capacity is insufficient. From the standpoint of preventing this, it is preferably not more than the upper limit of the above range.

The water-absorbing polymer 22 used in the present invention has a maximum absorption of artificial urine of 24 g / g or more, preferably 25 g / g or more, more preferably 26 g / g or more, particularly preferably 27 g / g or more, and 40 g / g. g or less, preferably 38 g / g or less, more preferably 36 g / g or less, particularly preferably 34 g / g or less, more specifically 24 g / g or more and 40 g / g or less, preferably 25 g / g or more and 38 g / g or less. Hereinafter, it is more preferably 26 g / g or more and 36 g / g or less, and particularly preferably 27 g / g or more and 34 g / g or less.
By setting the maximum absorption amount of the water-absorbing polymer 22 to be equal to or more than the lower limit of each of the above ranges, it becomes easy to sufficiently absorb the liquid, the absorption capacity of the absorber 10 is sufficient, and the liquid return amount is reduced. There is no problem with the maximum absorption amount of the water-absorbing polymer 22 being too large, but it is preferably not more than the upper limit of each of the above ranges.

In the present invention, a water-absorbing polymer that impairs the liquid permeability at a relatively low swelling ratio is used.
Specifically, a water-absorbing polymer having a swelling ratio of 60% or less with respect to a swelling ratio at the time of maximum swelling and a liquid passing rate under 2 kPa pressure of 40 g of artificial urine having the following composition is used.
The higher the swelling ratio of the water-absorbing polymer, the lower the liquid passing speed under pressure. Therefore, if the liquid passing rate under a pressure of 2 kPa is 100 g / min or less at a swelling rate of 60% or less, the liquid passing rate at a swelling rate of 60% is necessarily 100 g / min or less. In the present invention, a water-absorbing polymer having a low liquid passing rate under pressure of 100 g / min or less is used even at a low swelling ratio of 60% or less.
Artificial urine composition: 1.94% urea, 0.80% sodium chloride, 0.06% calcium chloride, 0.11% magnesium sulfate, 0.085% ammonium dihydrogen phosphate, 0.015% diammonium hydrogen phosphate , 96.99% ion-exchanged water.
The artificial urine having this composition is also used when determining the maximum amount of artificial urine absorbed as described above.

The maximum swelling means a state in which the water-absorbing polymer is sufficiently immersed in artificial urine and the amount of absorbed water (V∞) of the water-absorbing polymer is not changed. Further, the swelling ratio in this state is 100%. On the other hand, when the absorption amount of the water-absorbing polymer at a certain time t and V _t, swelling capacity at time t is represented by the following formula.
Swelling ratio (%) = (V _t / V∞) × 100
A method for measuring the liquid passing speed under 2 kPa pressure at a swelling ratio of 60% with respect to the swelling ratio at the time of maximum swelling will be described later in Examples.
FIG. 2 shows the relationship between the swelling ratio and the flow rate under pressure of 2 kPa at each swelling ratio in the case of two types of water-absorbing polymers that have been widely used in the past for a preferred example of the water-absorbing polymer used in the present invention. It is a conceptual diagram shown with it.

  The water-absorbing polymer used in the present invention is an excretion solution under a load of 2 kPa (40 g of artificial urine) in a state where the swelling ratio is 60% (or, it may be converted to 60% from two points of linear correction sandwiching 60%). ) Under a pressure of 2 kPa is 100 g / min or less, preferably 50 g / min or less, and more preferably 30 g / min or less. About a minimum, 1 g / min or more is preferable, More preferably, it is 3 g / min or more, More preferably, it is 5 g / min or more. More specifically, the preferable range is 1 g / min to 100 g / min, preferably 3 g / min to 50 g / min, more preferably 5 g / min to 50 g / min, and particularly preferably 5 g. / Min to 30 g / min.

  The water-absorbing polymer used in the present invention has a liquid passage speed of 100 g / min when the drainage liquid (artificial urine 40 g) under a load of 2 kPa is pressurized at 2 kPa in a state where the liquid passage speed is less than 60%. Or less, preferably 50 g / min or less, more preferably 30 g / min or less. About a minimum, 1 g / min or more is preferable, More preferably, it is 3 g / min or more, More preferably, it is 5 g / min or more. More specifically, the preferable range is 1 g / min to 100 g / min, preferably 3 g / min to 50 g / min, more preferably 5 g / min to 50 g / min, and particularly preferably 5 g. / Min to 30 g / min. It is more preferable to show a value within the following range.

The pressurization value of 2 kPa is an example of an average pressure when the baby pressurizes the absorbent body 10 when the absorbent body 10 is worn.
In general, a commercially available water-absorbing polymer does not cause gel blocking as much as possible by increasing the degree of surface cross-linking of the water-absorbing polymer (or its precursor) like the absorbent polymer (1) shown in FIG. The design is such that the flow rate is improved (the flow rate under a pressure of 2 kPa is 100 g / min or more even at a swelling ratio of 100%). Such a water-absorbing polymer imparts liquid permeability at the expense of the amount of water absorption. Therefore, when used in the absorbent body 10, although the absorption speed is very high in absorption due to repeated excretion, the absorption capacity is small and high. It is insufficient to expect an absorption amount and a low liquid return amount.

  Further, the water-absorbing polymer disclosed in Patent Documents 1 and 2 is designed to cause gel blocking at a swelling ratio of 100%, like the absorbent polymer (2) shown in FIG. When the magnification is 60% or less, the liquid passing speed under 2 kPa pressure is 100 g / min or more and no gel blocking occurs. When such a water-absorbing polymer is used for the absorbent body 10, the absorption speed is high and the absorption capacity is large in absorption by repeated excretion, but it is insufficient to expect a low liquid return amount. The utilization efficiency of the water-absorbing polymer present in a specific part of the absorbent body 10 to be subjected to the liquid return phenomenon (here, the same meaning as the swelling ratio) is 50 to 100%, and the pore water skin present in the specific part In order to effectively suppress the movement to the side, a water-absorbing polymer that is in a state where gel blocking occurs at a low utilization efficiency of 50 to 70% is required.

The water-absorbing polymer 22 in which the liquid passing speed under a pressure of 2 kPa is set in the above range is in a state of causing gel blocking at low utilization efficiency. Therefore, in the state where the liquid (for example, urine) is discharged and under pressure where the load of the wearer is applied to the absorbent body 10, unlike the absorbent body of the present invention, the absorbent body without the recess 11 is gel-blocking. Occurs, the diffusion of the liquid into the absorber is remarkably reduced, and the absorption capacity of the absorber is small and the liquid return amount is large. On the other hand, for example, as shown in FIG. 1, the absorbent body of the present invention includes a concave portion 11 as a concave portion having a depth D of 20% to 100% of the thickness T of the absorbent body 10. In the absorbent body 10 having the recesses 11, the recesses 11 (fluid passages) are secured until the water-absorbing polymer 22 protrudes inside the recesses 11 and is closed by the water-absorbing polymer 22. Therefore, while the liquid permeability in the recess 11 is ensured, the liquid can be quickly diffused widely into the absorber. Therefore, the absorption capacity of the absorber increases. And if the water absorbing polymer 22 protrudes inside the recessed part 11 and the recessed part 11 is block | closed by the water absorbing polymer 22, gel blocking will occur and the spreading | diffusion of the inside of an absorber will fall remarkably. At this time, the movement of the interstitial water existing in the specific part of the absorbent body 10 that is the target of the liquid return phenomenon is effectively suppressed by gel blocking. Accordingly, the liquid return amount is reduced.
Accordingly, the liquid passing speed of the water-absorbing polymer 22 under a pressure of 2 kPa needs to be in a state where gel blocking occurs with low utilization efficiency (that is, 60% or less here). The upper limit of the liquid passing speed under 2 kPa pressurization reflects a state where liquid permeability is not expressed. Further, when the liquid passing rate under a pressure of 2 kPa is lower than the lower limit, the liquid cannot be sufficiently diffused only by the liquid permeability in the recess 11. Therefore, the liquid passing speed under the pressure of 2 kPa is set to the above-described range.

  The thickness T of the absorbent body 10 is preferably 0.5 mm or more, more preferably 1 mm or more, further preferably 1.5 mm or more, and preferably 20 mm or less, more preferably 10 mm or less, still more preferably 5 mm or less. More specifically, it is preferably 0.5 mm or more and 20 mm or less, more preferably 1 mm or more and 10 mm or less, and further preferably 1.5 mm or more and 5 mm or less. If the thickness T of the absorbent body 10 is too thin, it will be difficult to secure a sufficient amount of absorption, making it difficult to wear for a long time, and if it is too thick, the fit of the absorbent body to the body (body compatibility) will be reduced. .

  The said absorber 10 has the recessed part 11 in the one surface side. The recess 11 is preferably a groove. The recess 11 has, for example, a plurality of vertical grooves 11A extending in the longitudinal direction (Y direction) of the absorber 10, and a plurality of horizontal grooves 11B extending in the width direction (X direction) orthogonal to the longitudinal direction. For example, the lateral grooves 11B are arranged by shifting the arrangement position in the longitudinal direction for each row in the longitudinal direction. These vertical grooves 11A and horizontal grooves 11B are connected to form a continuous groove (concave portion). Various arrangements of the recesses 11 can be adopted. For example, a part of the depressions 11 may be arranged in an oblique lattice shape or may be a curved shape.

  The depth D of the recess 11 is preferably 20% or more of the thickness T of the absorbent body 10, more preferably 25% or more, still more preferably 30% or more, particularly preferably 50% or more, and 100%. Or less, more preferably 90% or less, still more preferably 80% or less, more specifically 20% or more and 100% or less, preferably 25% or more and 100% or less, more preferably 30% or more. 100% or less, more preferably 50% or more and 100% or less, or 20% or more and 90% or less, preferably 20% or more and 80% or less, more preferably 30% or more and 80% or less, and still more preferably 50%. % To 80%. By making the depth of the concave portion 11 larger than the above ranges, the concave portion 11 is prevented from being immediately filled with the liquid supplied to the absorbent body 10, and the absorption becomes insufficient. Further, the depths D of the recesses 11 may not all be the same depth.

  Further, the total area of the recesses 11 in plan view with respect to the area of the absorber 10 in plan view (the sum of the total area of each separated block 12 and the total area of the recesses 11) is preferably 10% or more, more preferably 12% or more, more preferably 15% or more, particularly preferably 20% or more, and preferably 50% or less, more preferably 40% or less, still more preferably 35% or less, more specifically, It is preferably from 10% to 50%, more preferably from 12% to 40%, still more preferably from 15% to 35%, particularly preferably from 20% to 35%. If the total area of the recesses 11 is less than 10%, the recesses 11 are immediately filled with the supplied liquid and the absorption becomes insufficient. On the other hand, if the total area of the concave portion 11 becomes too large, the diffusibility of the liquid increases and the liquid escapes (a phenomenon in which the liquid passes through without being accumulated in the absorber).

  The width of the recess 11 (vertical groove 11A, horizontal groove 11B, etc.) is preferably 1 mm or more, more preferably 2 mm or more, still more preferably 3 mm or more, and preferably 20 mm or less, more preferably 15 mm or less, even more preferably. Is 12 mm or less, particularly preferably 10 mm or less, more specifically preferably 1 mm or more and 20 mm or less, more preferably 2 mm or more and 15 mm or less, still more preferably 2 mm or more and 12 mm or less, and particularly preferably 3 mm. It is 10 mm or less. If the width of the recess 11 is too wide, the diffusibility of the liquid will increase and the liquid will escape. If it is too narrow, the liquid permeability decreases and the range in which the liquid is diffused through the concave portion 11 becomes narrow, or the concave portion 11 is immediately filled with the supplied liquid, and the absorption becomes insufficient (the amount of liquid absorbed decreases). Liquid is returned to the absorber surface).

In the absorbent body 10, the basis weight in the portion 10 </ b> B having the recess 11 is preferably lower than the basis weight in the portion 12 other than the recess 11. The basis weight here is the total basis weight of the hydrophilic fiber and the water-absorbing polymer, but also when comparing only the basis weight of the hydrophilic fiber, the basis weight of the water-absorbing fiber of the portion 10B having the recess 11 However, it is preferable that the basis weight of the hydrophilic fiber in the portion 12 other than the concave portion 11 is lower. In addition, the recessed part formed by embossing has the same basis weight as the recessed part part.
Since the basis weight of the bottom of the recess is lower than the basis weight of the part other than the bottom of the recess, liquid diffusion prevails, and in absorbing the drained liquid by repeated drainage, both high absorption capacity and low liquid return are compatible. The effect of achieving high absorption performance from the start of use to the end of use is more reliably achieved.
The basis weight of the bottom of the recess is preferably 80% or less of the basis weight of the portion other than the bottom of the recess, more preferably 70% or less, and further preferably 60% or less.

As for the recessed part 11, it is desirable for the total area of the recessed part which has an area of 0.2 cm < ² > or more to be 50% or more and 100% or less of the total area of all the recessed parts.
The “recesses having an area of 0.2 cm ² or more” and “recesses” of the “all recesses” here are recesses having a depth of 20% to 100% of the thickness of the absorber.
The area of the recess 11 is more preferably 1 cm ² or more, further preferably 1.5 cm ² or more, further preferably 2 cm ² or more, and particularly preferably 3 cm ² or more. When the total area of the recesses having an area of 0.2 cm ² or more is 50% or more of the total area of all the recesses, the effect of diffusing the liquid through the recesses 11 is reduced, or the recesses 11 are immediately caused by the supplied liquid Is prevented from becoming insufficiently absorbed. As a result, the amount of liquid absorbed is reduced and returned to the absorber surface.

Moreover, when the absorber 10 exists in the bottom part of the recessed part 11, it is preferable that the density of the absorber 10 of the bottom part of the said recessed part 11 is lower than the density of absorbers 10 other than the bottom part of the recessed part 11. FIG.
The density of the absorbent body 10 at the bottom of the recess 11 is preferably 0.01 g / cm ³ or more, more preferably 0.02 g / cm ³ or more, and preferably 0.09 g / cm ³ or less, more preferably 0.08 g / cm ³ or less, more preferably 0.07 g / cm ³ or less, more specifically preferably 0.09 g / cm ³ or less, more preferably 0.01 g / cm ³ or more and 0 or less. more preferably .08g / cm ³ or less or less 0.02 g / cm ³ or more 0.07 g / cm ^3. When the density is low, there is a tendency that the liquid does not easily migrate to the absorber. On the other hand, if the density is too high, voids in the absorbent body 10 are reduced, so that the amount of liquid that can be received is reduced and diffusion in the concave portion 11 is likely to occur, and liquid to the absorbent body 10 other than the bottom of the concave portion 11 is liable to occur. The delivery will be reduced and it will be easy to leak.

Density of the absorbent body 10 other than the bottom of the recess 11, 0.03 g / cm ³ or more, more preferably 0.05 g / cm ³ or more, more preferably 0.06 g / cm ³ or more, and, 0 .3g / cm ³ or less, and more preferably 0.2 g / cm ³ or less, still more preferably at 0.15 g / cm ³ or less, more specifically, preferably 0.03 g / cm ³ or more zero. 3 g / cm ³ or less, and more preferably not more than 0.05 g / cm ³ or more 0.2 g / cm ^3, particularly preferably not 0.06 g / cm ³ or more 0.15 g / cm ³ or less.
When the density is too low, the capillary force hardly acts and it is difficult to guide the liquid that has passed through the concave portion 11 to the absorbent body 10 other than the bottom portion of the concave portion 11, and it becomes difficult to hold the liquid. On the other hand, even when the density is too high, the absorbent polymer tends to inhibit swelling, and it becomes difficult to hold the liquid that has passed through the liquid-receiving layer portion 11.

  Since the density of the absorber 10 at the bottom of the recess 11 is made lower than the density of the other absorbers 10 in this way, the liquid supplied into the recess 11 tends to spread in the recess 11 and the absorption at the bottom of the recess 11 is also achieved. It is easily absorbed by the body 10. In addition, when the density of the absorber 10 at the bottom of the recess 11 and the density of the absorber 10 at the side wall of the recess 11 are equal, the liquid supplied into the recess 11 enters the absorber 10 from the bottom and side wall of the recess 11. To be absorbed. On the other hand, when the density of the absorber 10 at the bottom of the recess 11 is higher than the density of the other absorbers 10, the liquid supplied to the recess 11 is absorbed into the absorber 10 from the side wall of the recess 11, and the recess 11. It becomes difficult to spread widely through. For this reason, the amount of liquid absorption decreases. Therefore, the density is as described above.

  The absorbent body 10 of the present invention has a high absorption in the absorption of the excretion liquid by repeated excretion due to the arrangement of the recesses 11 and the use of the water-absorbing polymer 22 that exhibits gel blocking at a low swelling ratio. It achieves both capacity and low liquid return, and has an excellent effect of exhibiting high absorption performance from the start of use to the end of use.

For example, an example of an absorption process when the drainage liquid is supplied to the absorber 10 described above will be described with reference to FIG. 3 which is a conceptual diagram.
As shown in FIG. 3A, an excretory liquid (for example, urine) 60 is supplied to the absorber 10. Then, as shown in FIG. 3B, the drainage liquid 60 quickly flows into the recess 11 of the absorbent body 10, and since the flow path of the recess 11 is secured, it quickly travels through the recess 11 and spreads in all directions. Go. At this time, it also diffuses into the absorber 10 at the bottom of the recess 11 and the side wall. In addition, when the absorber block 12 is denser than the absorber 10B at the bottom of the recess 11, the drained liquid is mainly diffused toward the absorber block 12. And as shown in FIG.3 (c), the excretion liquid 60 spreads by making the recessed part 11 into a flow path, and is spread | diffused by the absorber 10B of the bottom part of the recessed part 11, and is absorbed by the absorber block 12 by capillary force soon, The excreted liquid is stored in the absorber block 12 and fixed. In this way, the absorbent body 10 achieves high absorption performance and high absorption speed.

Moreover, since the absorption capacity of the absorber 10 is improved by using the above-described water-absorbing polymer 22, the amount of the water-absorbing polymer 22 used is reduced and the thin film of the absorber 10 when the absorption amount is the same as that of the conventional product. Can be realized. Therefore, there are also advantages such as thinning and downsizing of an absorbent article using the absorbent body 10 of the present invention.
Furthermore, since the absorber 10 has the recess 11, the degree of freedom with respect to the deformation of the absorber 10 is increased. For this reason, the body suitability of the absorbent body 10 is enhanced, and the liquid can be passed to the end of the absorbent body 10. Therefore, the liquid absorption amount of the absorbent body 10 can be improved.

<About the excretion area>
The excretory part region is centered on the area center of the second part from the front (abdominal side) when the absorbent body is divided into four parts by dividing the length in the longitudinal direction into four parts. This is an area of 100 mm in length and width. When this 100 mm long and horizontal region protrudes from the absorber, the region where the vertical and horizontal 100 mm region overlaps with the absorber is used.
The space volume of the recess in the excretion region is preferably in the range of 0.8 cm ^{3 to} 30 cm ³ . The basis weight of the water-absorbing polymer present in the excretory part region, 50 g / m ² or more, more preferably 100 g / m ² or more, more preferably 200 g / m ² or more, and, 500 g / m ² or less Preferably, it is 450 g / m ² or less, more preferably 400 g / m ² or less, more specifically 50 g / m ² or more and 500 g / m ² or less, more preferably 100 g / m ² or more and 450 g. / M ² or less, more preferably 200 g / m ² or more and 400 g / m ² or less.
The space volume of the recess of the excretion part region is measured under non-pressurization in a state where the absorber does not absorb any liquid, and the area of the recess present in the excretion part region when the absorber is viewed in plan view, It calculates from the depth (thickness) of a recessed part.

<Measurement of absorber thickness and recess depth (thickness)>
For example, there are a method of measuring the cross section of the absorber with a Keyence microscope, a method of measuring with a Keyence laser microscope, and the like.
<Measurement method of basis weight and density of absorber, basis weight and density of bottom of recess>
First, the absorbent body is viewed in a plan view, cut into portions other than the bottom of the recess and the bottom of the recess, and the mass and the planar size (area) are measured to calculate the basis weight. Also, using a microscope, focus on the bottom of the recess, measure the area including one or more parts other than the bottom of the recess and the bottom of the recess, and binarize the bottom of the recess from the image. The area ratio of the bottom of the recess is derived by the image processing apparatus, and the difference is the area ratio of the portion other than the bottom of the recess. If necessary, use manual correction of the image analyzer. It is preferable to image the entire absorber at once and obtain the area ratio using an image analysis device. However, in the case of performing measurement using a plurality of images, for example, a pixel (pixel) Sb of a portion other than the bottom of the recess in a predetermined region. Either ΣSb, the sum ΣSt of the bottom pixel (pixel) St of the recess, or the sum ΣSb + ΣSt of the absorber pixels (pixel), and calculate the area ratio, or representative area of parts with different area ratios It can be obtained from the sum of numerical values obtained by multiplying the rate and the ratio of the area of each part in the total area. The area ratio of the portion other than the bottom of the recess is ΣSb / (ΣSb + ΣSt), and the area ratio of the bottom of the recess can be calculated by ΣSt / (ΣSb + ΣSt).
Based on the measurement result, the density is calculated by the calculation of density = basis weight / thickness.

  With respect to repeated excretion, the utilization efficiency of the water-absorbing polymer is 50 to 100%, and considering the preferable range of water absorption of artificial urine: 24 g / g or more and 40 g / g or less, the water-absorbing polymer is 12 times or more and 40 times. A design is desired in which when the artificial urine is absorbed twice or less, the concave portion is buried and gel blocking occurs. The depth of the recess is 10% or less, preferably 5% or less, more preferably 3% or less, and further preferably 0% with respect to the thickness of the absorber after liquid absorption.

The absorbent body 10 of the present invention preferably contains fine powder of a water-absorbing polymer in the excretion area. Here, the fine powder is a water-absorbing polymer particle having a particle size of 150 microns or less.
The water-absorbing polymer present in the excretory part region preferably has a proportion (fine powder content) of water-absorbing polymer particles having a particle size of 150 microns or less of 1% or more and 10% or less.
From the basis weight of the water-absorbing polymer present in the excretion part region and the fine powder content in the water-absorbing polymer (described later: preferably 1 to 10%), the amount of fine powder present in the excretion part region is calculated. The amount of fine powder present in the excretion region is preferably 0.005 g or more, more preferably 0.01 g or more, still more preferably 0.02 g or more, and preferably 0.5 g or less, more preferably 0.45 g. In the following, it is more preferably 0.4 g or less, more specifically, preferably 0.005 g or more and 0.5 g or less, more preferably 0.01 g or more and 0.45 g or less, and further preferably 0.02 g or more and 0.0. 4 g or less. It is conceivable that the fine powder existing in the excretion part region moves to the concave part of the excretion part region due to the movement or walking of the diaper wearer. At this time, the saturated swelling volume v of the fine powder (if present in the concave part, body pressure is applied). hard to order, the swelling volume of the non-pressurized) is often higher than the equivalent relative to the spatial volume V of the recess of the discharging part regions (0.8 cm ³ or more 30 cm ³ or less), the recesses filled effectively gel blocking Will occur.
The equivalent or more means that the saturated swelling volume v of the fine powder is v ≧ V with respect to the spatial volume V of the concave portion of the excretory part region.
Further, the saturation swelling volume v of the fine powder is measured by the following method. Put the fine powder of the amount existing in the excretion area (calculated from the basis weight of the water-absorbing polymer in the excretion area and the fine powder content) into the measuring cylinder, add an excessive amount of artificial urine, and leave it for 60 minutes or more, then surplus The volume when the artificial urine was removed and the fluidity of the gel of the water-absorbing polymer disappeared.

The water-absorbing polymer 22 used in the present invention will be described in detail.
The water-absorbing polymer 22 is polymer particles having water absorption, and the production method is not limited. From the viewpoint of water absorption properties, it is mainly a post-crosslinked water-absorbing polymer. The shape is not particularly limited, and may be spherical, lump, grape-like, indefinite shape, porous, powdery or fibrous. The average particle size of the water-absorbing polymer 22 is 100 μm or more and 1000 μm or less, preferably 150 μm or more and 650 μm or less, in order to suppress dropping from the product, suppression of movement or deterioration of feeling of use (roughness). Preferably they are 200 micrometers or more and 500 micrometers or less. The water-absorbing polymer of the present application that easily causes gel blocking can be obtained by appropriately adjusting the amount of the crosslinking agent used and the water content of the water-absorbing polymer at the time of crosslinking.

Since the water-absorbing polymer 22 is desired to be in a state of causing gel blocking at low utilization efficiency, (1) it contains a large amount of water-absorbing polymer particles (fine powder) having a small particle diameter and (2) It is preferable to contain a lot of soluble components (components that dissolve in the liquid). When there are many fine powders, the gap | interval between the water absorbing polymer gels in the absorber 10 will become narrow, and it can be in the state which causes a gel blocking more effectively. Moreover, when there is much soluble content in a water absorbing polymer, the space | interval of the water absorbing polymer gel in the absorber 10 will become narrow, or the viscosity of the liquid of the gel vicinity will rise, and will cause a gel blocking more effectively It can be

  The proportion of fine powder having a particle size of 150 μm or less in the water-absorbent polymer 22 is preferably 1% or more, more preferably 2% or more, still more preferably 3% or more, and preferably 10% or less, more preferably 9 % Or less, more preferably 8% or less, more specifically 1% or more and 10% or less, more preferably 2% or more and 9% or less, and further preferably 3% or more and 8% or less. is there. When there are few fine powders, the effect which can be in the state which causes a gel blocking is small. Moreover, since there are many fine powders, workability is deteriorated in product processing, and troubles in which fine powders adhere to the skin of consumers are likely to occur.

The ratio of the soluble component in the water-absorbing polymer 22 is preferably 1% or more, more preferably 2% or more, still more preferably 3% or more, particularly preferably 5% or more, as the internal ratio of the water-absorbing polymer. And 15% or less is preferable, More preferably, it is 13% or less, More preferably, it is 11% or less, Most preferably, it is 10% or less, More specifically, 1% or more and 15% or less are preferable, More preferably, 2 % To 13%, more preferably 3% to 11%, and particularly preferably 5% to 10%. When there is little soluble content, the effect which can be in the state which causes a gel blocking is small. Moreover, since the trouble which a soluble content adheres to a consumer's skin will generate | occur | produce when there is much soluble content, the said range is preferable.
A method for measuring the soluble content will be described later in Examples.

  Further, the water absorption amount of the water-absorbing polymer 22 to the artificial urine and the liquid passing speed under 2 kPa pressure are as described above.

  As an example, the water-absorbing polymer 22 can be obtained by polymerizing one or more kinds selected from the following monomers. Moreover, a crosslinking process is performed as needed. The polymerization method is not particularly limited, and various generally known water-absorbing polymer methods such as a reverse phase suspension polymerization method and an aqueous solution polymerization method can be employed. Thereafter, the polymer is subjected to operations such as pulverization and classification as necessary, and surface treatment is performed as necessary.

  The monomer used in producing the water-absorbing polymer 22 is a monomer that is water-soluble and has a polymerizable unsaturated group. Specifically, olefinic unsaturated carboxylic acid or salt thereof, olefinic unsaturated carboxylic acid ester, olefinic unsaturated sulfonic acid or salt thereof, olefinic unsaturated phosphoric acid or salt thereof, olefinic unsaturated phosphate ester And vinyl monomers having polymerizable unsaturated groups such as olefinically unsaturated amines, olefinically unsaturated ammonium salts, and olefinically unsaturated amides.

  Examples of the olefinic unsaturated carboxylic acid or a salt thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, alkali metal salts and ammonium salts thereof.

  Examples of olefinic unsaturated carboxylic acid esters include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, and phenoxypolyethylene glycol (meth). An acrylate etc. are mentioned.

  Examples of the olefinic unsaturated sulfonic acid or a salt thereof include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, 2- (meth) acryloylethane sulfonic acid, 2- (Meth) acryloylpropane sulfonic acid or a salt thereof may be mentioned.

  Examples of the olefinic unsaturated phosphoric acid or a salt thereof include (meth) acryloyl (poly) oxyethylene phosphoric acid ester or a salt thereof.

  Examples of the olefinic unsaturated amine include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and N, N-dimethylaminopropyl. (Meth) acrylamide etc. are mentioned.

  Examples of the olefinic unsaturated ammonium salt include quaternary ammonium salts of the above olefinically unsaturated amines.

  Examples of the olefinically unsaturated amide include (meth) acrylamide, methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) ) (Meth) acrylamide derivatives such as acrylamide, vinylmethylacetamide and the like.

  Specific examples of the other monomer include nonionic hydrophilic group-containing unsaturated monomers such as vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, N-acryloylpyrrolidine, and N-vinylacetamide.

  In the present specification, (meth) acrylate means acrylate or methacrylate, (meth) acrylamide means acrylamide or methacrylamide, and (meth) acryloyl means acryloyl or methacryloyl.

  Among these monomers, olefinic unsaturated carboxylic acids or salts thereof are preferred, acrylic acid, methacrylic acid, alkali metal salts, alkaline earth metal salts or ammonium salts thereof are more preferred, and acrylic acid, alkali metal acrylate salts. (Lithium salt, sodium salt, potassium salt, etc.) and ammonium acrylate are further preferred.

  Examples of the crosslinking agent include N, N-diallylacrylamide, diallylamine, triallylamine, diallylmethacrylamide, diallyl phthalate, diallyl malate, diallyl terephthalate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, tetraallyloxy. Polyallyl compounds such as ethane, pentaerythritol triallyl ether poly (meth) allyloxyalkane, divinylbenzene, N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol Di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, glycerin tri (meth) acrylate Polyvinyl compounds such as glyceryl acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol Polyglycidyl ethers such as diglycidyl ether and polyglycerin polyglycidyl ether; haloepoxy compounds such as epichlorohydrin, epibromhydrin and α-methylepichlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; glycerin and polyvinyl Polyols such as alcohol and polyether-modified silicone; ethylenediamine, diethylenetria Polyamines such as amine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, polyvinylpyrrolidone, amino-modified silicone; glycidyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl ( Hydroxy vinyl compounds such as (meth) acrylate; polyvalent isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; polyvalent oxazoline compounds such as 1,2-ethylenebisoxazoline; urea, thiourea, guanidine, dicyandiamide, Carbonic acid derivatives such as 2-oxazolidinone, 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3- Oxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, 1,3-dioxopan-2-one Examples thereof include alkylene carbonate compounds such as polyvalent metal compounds (inorganic salts or organic metal salts such as hydroxides or chlorides) composed of cations such as calcium, magnesium, zinc, aluminum, iron, zirconium and titanium. Ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerin, Polyglycerol, 2-butene-1,4-diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1 , 2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol, sorbitol, etc. May be used alcohol compounds, these can be used alone or in admixture.

  In general, the higher the water content of the water-absorbing polymer, the more the cross-linking agent penetrates into the water-absorbing polymer and the absorption performance of the water-absorbing polymer tends to decrease. By appropriately adjusting the amount of the crosslinking agent used and the water content of the water-absorbing polymer, it is possible to balance the water absorption amount of the water-absorbing polymer and the liquid passing speed.

  The amount of the crosslinking agent used for the absorbent polymer 22 of the present application is 0.001 wt% or more with respect to the total polymerizable monomer (polymerizable monomer other than the crosslinking agent having two or more polymerizable unsaturated groups). Preferably, it is 0.01 wt% or more, and preferably 0.1 wt% or less, more preferably 0.08 wt% or less, more specifically 0.001 wt% or more and 0.1 wt% or less. Is preferable, and the range of 0.01 wt% or more and 0.08 wt% or less is more preferable. When using a crosslinking agent or an aqueous solution thereof, a hydrophilic organic solvent, an acid or a pH buffering agent may be mixed and used.

The crosslinking agent is preferably added in two or more stages in a state where the water content of the water-absorbing polymer is different.
When performing crosslinking in two or more stages, the water content of the water-absorbing polymer is 100% or more, preferably 120% or more, and the amount of the crosslinking agent used is 0 with respect to the total polymerizable monomer. 0.001 wt% or more is preferable, more preferably 0.005 wt% or more, and preferably 0.02 wt% or less, more preferably 0.01 wt% or less, and more specifically 0.001 wt% or more. 0.02 wt% or less is preferable, and a range of 0.005 wt% or more and 0.015 wt% or less is more preferable. In the second and subsequent crosslinking, the water content of the water-absorbing polymer is 50% or less, preferably 45% or less, and the amount of the crosslinking agent used is preferably 0.02 wt% or more based on the total polymerizable monomer, more Preferably, it is 0.03 wt% or more, and preferably 0.09 wt% or less, more preferably 0.07 wt% or less, more specifically 0.02 wt% or more and 0.09 wt% or less, A range of 0.03 wt% or more and 0.07 wt% or less is more preferable.

In the production of the water-absorbing polymer, the polymer particles obtained by using a polymer compound having a functional group can be subjected to surface treatment. Examples of the polymer compound include polyethyleneimine, polyvinyl alcohol, Examples include allylamine polyacrylic acid (sodium salt) and copolymers thereof. Moreover, although this high molecular compound may be used independently, you may use together with said various crosslinking agent. The amount of the crosslinking agent having two or more polymerizable unsaturated groups or the crosslinking agent having two or more reactive groups may be any amount according to the desired performance of the water-absorbing polymer of the final product. However, it is preferably 0.001 wt% or more, more preferably 0.01 wt% or more, based on the total polymerizable monomer (polymerizable monomer other than the crosslinking agent having two or more polymerizable unsaturated groups), And 0.1 wt% or less is preferable, More preferably, it is 0.05 wt% or less, More specifically, 0.001 wt% or more and 0.1 wt% or less are preferable, 0.01 wt% or more and 0.05 wt% or less The range of is more preferable. The amount of the polymer compound used is preferably 0.01 wt% or more, more preferably 0.05 wt% or more, and preferably 20 wt% or less, more preferably 10 wt%, based on the water-absorbing polymer. More specifically, it is preferably 0.01 wt% or more and 20 wt% or less, and more preferably 0.05 wt% or more and 10 wt% or less.
When using a crosslinking agent or an aqueous solution thereof, a hydrophilic organic solvent, an acid or a pH buffering agent may be mixed and used.

Examples of surface treatment agents include surface modifying oils such as modified silicones; polyvalent metal compounds such as aluminum sulfate, potassium alum, ammonium alum, sodium alum, (poly) aluminum chloride, and their hydrates; polyethyleneimine, Polycation compounds such as polyvinylamine and polyallylamine; inorganic fine particles such as silica, alumina, titanium oxide, zinc oxide, bentonite; and the like. These may be used alone or in combination of two or more. Also good.
In the present invention, it is necessary to perform the surface treatment to such an extent that gel locking occurs at 50 to 70% of the utilization efficiency of the water-absorbing polymer (here, the same meaning as the swelling ratio).
In the production of the water-absorbing polymer, various additives can coexist within a range that does not adversely affect the polymer. Specific examples of such additives include starch-cellulose, starch-cellulose derivatives, polyvinyl alcohol, polyacrylic acid (salt), cross-linked polyacrylic acid (salt), polyethylene glycol, polyvinylpyrrolidone, and the like. Polymerization inhibitors such as auxiliaries and quinones, chain transfer agents, chelating agents and the like.

The hydrophilic fibers constituting the absorbent body 10 together with the water-absorbing polymer 22 include (1) softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), and thermomechanical pulp (TMP). ) Wood pulp cotton pulp, bast fibers such as cocoons, cocoons, and husks, natural cellulose fibers such as cocoons, bamboo, kenaf, hemp, etc., (2) regenerated cellulose fibers such as rayon and cupra, (3 ) Hydrophilic synthetic fibers such as polyvinyl alcohol fiber and polyacrylonitrile fiber, (4) Synthetic fibers such as polyethylene terephthalate (PET) fiber, polyethylene (PE) fiber, polypropylene (PP) fiber, and polyester fiber are hydrophilized with a surfactant. What was processed is mentioned. The hydrophilic fibers are preferably natural cellulose fibers or regenerated cellulose fibers, and more preferably pulp fibers made of wood pulp. The pulp fiber mentioned here includes ECF (elementary chlorin-free) bleached pulp and TCF (total chlorin-free) bleached pulp that do not use a chlorine compound for pulp bleaching.
The above-mentioned various hydrophilic fibers can be used singly or in combination of two or more.

  Next, as a preferred embodiment of the absorbent article according to the present invention, a disposable diaper (hereinafter referred to as a diaper) 50 to which the absorbent body 10 is applied will be described with reference to FIG. In addition, in FIG. 4, the surface sheet 16 of the center part of the longitudinal direction Y of the diaper 50 is notched.

As shown in FIG. 4, the diaper 50 has a constricted central portion in the longitudinal direction Y corresponding to the crotch portion as a whole. The top sheet 16 and the back sheet 17 respectively extend outward from the left and right side edges and both front and rear ends of the absorbent body 10. The top sheet 16 is smaller in the width direction X than the back sheet 17 in the width direction X.
The diaper 50 is an unfolded diaper, and a pair of fastening tapes FT are attached to both side edges at one end in the longitudinal direction Y. Further, a landing tape LT is attached on the back sheet 17 at the other end.
It is preferable that the surface sheet 16 is not joined to the concave portion 11 of the absorbent body 10 from the viewpoint that the water-absorbing polymer 22 can be sufficiently swollen.

  The diaper 50 includes a three-dimensional gather that can rise above the side edge of the absorbent body 10 in the width direction X. That is, a sheet material (side sheet) 18 for a three-dimensional gather having the gather elastic members 56 is arranged on both sides in the longitudinal direction Y of the diaper 50 to form a three-dimensional gather. In addition, on one side of the diaper 50 in the longitudinal direction Y, a pair of left and right leg elastic members 58 and 58 (two in the drawing) for leg gathers are arranged to form a leg gather. Yes. Leg elastic members 58 for leg gathers are arranged substantially linearly in an extended state in leg flaps extending outward from both side edges in the longitudinal direction Y of the absorbent body 10. In this case, the longitudinal direction Y in the diaper 50 and the longitudinal direction Y in the absorbent body 10 are the same direction.

  One or a plurality of gather elastic members 56 (two in the drawing) are fixed to one side edge of the sheet material 18 for three-dimensional gathers in an expanded state. The sheet material 18 is bonded to the surface sheet 16 along the longitudinal direction Y of the diaper 50 at positions outside the left and right side edges of the absorbent body 10 in the width direction X. It is a rising base. The sheet material 18 extends outward in the width direction X of the diaper 50 from the rising base end portion, and is joined to the back sheet 17 at the extended portion. The sheet material 18 is bonded onto the top sheet 16 at the front and rear end portions in the longitudinal direction Y of the diaper 50.

As the sheet material 18 for three-dimensional gathers, a liquid-impermeable or water-repellent and moisture-permeable material is preferably used. Examples of the sheet material 18 include a liquid-impermeable or water-repellent porous resin film, a liquid-impermeable or water-repellent nonwoven fabric, or a laminate of the porous resin film and the nonwoven fabric. Examples of the nonwoven fabric include thermal bond nonwoven fabric, spunbond nonwoven fabric, spunbond-meltblown-spunbond (SMS) nonwoven fabric, spunbond-meltblown-meltblown-spunbond (SMMS) nonwoven fabric, and the like. The basis weight of the sheet material 18 is preferably 5 g / m ² or more, more preferably 10 g / m ² or more, preferably 30 g / m ² or less, more preferably 20 g / m ² or less, more specifically. Is preferably 5 g / m ² or more and 30 g / m ² or less, more preferably 10 g / m ² or more and 20 g / m ² or less.

  As the surface sheet 16, various kinds of conventionally used diapers of this type can be used, and there is no limitation as long as it can transmit a liquid such as urine, and the liquid is permeable to the skin. It is preferably made of a soft material that hits the center. Examples thereof include woven fabrics and nonwoven fabrics made of synthetic fibers or natural fibers, and porous sheets. As an example, a non-woven fabric made of natural fibers such as cotton or a non-woven fabric made of various synthetic fibers subjected to a hydrophilic treatment can be used. For example, a core-sheath structure type (including side-by-side type) composite fiber using polypropylene or polyester as the core component and polyethylene as the sheath component is webbed by carding, and then nonwoven fabric (after this is opened at a predetermined location) by the air-through method. And may be subjected to a hole treatment). From the viewpoint of high liquid permeability (dry feeling), an apertured sheet made of polyolefin such as low density polyethylene can also be preferably used.

As the back sheet 17, various types conventionally used in this type of diaper can be used, and a liquid-impermeable or water-repellent and moisture-permeable sheet is preferably used. Specifically, in order to obtain sufficient water vapor permeability, a film made of synthetic resin such as polyethylene in which fine powder made of a filler such as calcium carbonate is dispersed is stretched and a porous film having fine holes is used. preferable. For example, what can be used as the sheet | seat material 18 for solid gather formation mentioned above can be used. Further, the width of the back sheet 17 is set to be approximately the same as the width of the absorbent body 10 and is disposed on the non-skin contact surface side of the absorbent body 10. You may distribute the laminated body of a nonwoven fabric and a film, etc. as a sheet | seat which comprises the external shape of a diaper.
The non-skin contact surface is a surface directed toward the clothing side (the side opposite to the wearer's skin side) when the diaper is worn. Hereinafter, the term skin contact surface may be used, and the skin contact surface is a surface directed toward the wearer's skin when the diaper is worn.

Further, in addition to the top sheet 16, the absorbent body 10, the back sheet 17, and the three-dimensional gather sheet, members may be appropriately present in accordance with applications and functions.
Furthermore, as shown in FIG. 4, an intermediate sheet 19 may be disposed between the top sheet 16 and the absorbent body 10. The intermediate sheet 19 can also be used as a mount. The mount is an absorbent paper that covers the absorbent body, that is, a core wrap material.
Examples of the intermediate sheet 19 include those that have the function of drawing and diffusing excreted liquid, those that reduce the amount of liquid return, those that suppress leakage of the water-absorbing polymer, and those that suppress collapse of the absorbent body. Used.
As a sheet | seat which has such performance, the nonwoven fabric and film which contain the fiber which has hydrophilic property, or was processed with the hydrophilic oil agent etc., or a porous body etc. are mentioned, for example. Examples of fibers for the intermediate sheet include (1) natural cellulose fibers such as wood pulp such as softwood kraft pulp and hardwood kraft pulp, and non-wood pulp such as cotton pulp and straw pulp, and (2) regenerated cellulose fibers such as rayon and cupra. (3) Hydrophilic synthetic fibers such as polyvinyl alcohol fibers and polyacrylonitrile fibers, (4) Synthetic fibers such as polyethylene terephthalate (PET) fibers, polyethylene (PE) fibers, polypropylene (PP) fibers, and polyester fibers. These can be used, and these can be used alone or in combination of two or more.

As the intermediate sheet 19, for example, paper such as tissue paper, woven fabric, non-woven fabric, knitted fabric, parchment, papyrus, pulp piled fiber, and the like can be used. Examples of the nonwoven fabric include a chemical bond nonwoven fabric, a thermal bond nonwoven fabric, an airlaid nonwoven fabric, a spunlace nonwoven fabric, a spunbond nonwoven fabric, a melt blown nonwoven fabric, a needle punch nonwoven fabric, and a stitch bond nonwoven fabric.
These sheets may be in a single layer state or may have a multilayer structure in which a plurality of layers are laminated to form a single sheet. In addition, a stretchable sheet (for example, a non-woven fabric (elastic non-woven fabric) including a fiber containing an elastic resin as a constituent fiber, a film containing an elastic resin (elastic film), or a foaming means forms a three-dimensional network in the structure) It is also possible to use an elastic porous body made of an elastic resin.

The basis weight of the intermediate sheet 19 is preferably 5 g / m ² or more, more preferably 10 g / m ² or more, and preferably 80 g / m ² or less, more preferably 30 g / m ² or less. Specifically, it is preferably 5 g / m ² or more and 80 g / m ² or less, particularly preferably 10 g / m ² or more and 30 g / m ² or less. Further, the thickness is preferably 0.05 mm or more, more preferably 0.1 mm or more, and preferably 5.0 mm or less, more preferably 3.0 mm or less, more specifically 0.05 mm. It is preferably 5.0 mm or less and particularly preferably 0.1 mm or more and 3.0 mm or less.
The intermediate sheet 19 may be disposed only between the top sheet 16 and the absorbent body 10, or may be disposed between the absorbent body 10 and the back sheet 17, and encloses the absorbent body 10. It may be arranged in such a way.

  The diaper 50 as an absorbent article of the present invention has a high absorption performance and a high absorption speed by the action of the absorbent body 10, deforms in accordance with a complex undulating skin surface, and makes contact with the surface without a gap. It has conformity and movement follow-up that is deformed in accordance with the movement of the wearer's body and maintains the state of contact with the skin surface. And the diaper 50 has the versatility that it can be used similarly to a normal expansion | deployment type diaper.

  The absorbent article is not limited to the above-described embodiment. As another embodiment, the absorbent article can be applied to this type of absorbent article, for example, a pants-type disposable diaper, an incontinence pad, an incontinence liner, and the like. . Moreover, it is effective not only for urine but also for menstrual blood, orimono, loose stool, and the like. In addition to the top sheet 16, the absorbent body 10, the back sheet 17, and the side sheet, members may be appropriately incorporated in accordance with the use and function. In addition, the material of the surface sheet 16, the absorber 10 and the back surface sheet 17 of the said embodiment, the conditions in a manufacturing method, and the dimensional specification of a product are not specifically limited, The various materials normally used can be used.

FIG. 5 is a view corresponding to FIG. 4 showing another embodiment of the absorbent body and absorbent article of the present invention. The absorbent body 10 ′ in the disposable diaper 10A shown in FIG. 5A includes convex portions 12A and 12A continuous in the longitudinal direction on both side portions in the longitudinal direction, and the block-shaped convex portions 12 are arranged in the longitudinal direction Y. A plurality of columns formed in series are formed, and the positions of the lateral grooves 11B in each column are the same. In the disposable diaper 10 </ b> B shown in FIG. 5B, the absorbent body 10 ″ has a plurality of concave portions 11 </ b> C that are long in the longitudinal direction Y and are spaced apart in the longitudinal direction Y and the width direction X.
The absorbent body may be produced by a mixed fiber of a water absorbent polymer and a hydrophilic fiber, or a laminated structure in which a water absorbent polymer layer is sandwiched between hydrophilic fiber sheets. The following absorber and absorbent article are further disclosed regarding the embodiment mentioned above.

<1> An absorbent body having a hydrophilic fiber and a water-absorbing polymer, the absorbent body having a recess having a depth of 20% to 100% of the thickness of the absorbent body,
The mass ratio represented by [mass of hydrophilic fiber] / [mass of water-absorbing polymer] in the absorber is 1/5 or more and 1 / 0.01 or less,
The water-absorbing polymer is an absorbent having a swelling ratio of 60% or less and a passing rate of 40 g of artificial urine having the following composition under a pressure of 2 kPa of 100 g / min or less.
Artificial urine composition: 1.94% urea, 0.80% sodium chloride, 0.06% calcium chloride, 0.11% magnesium sulfate, 0.085% ammonium dihydrogen phosphate, 0.015% diammonium hydrogen phosphate , 96.99% ion-exchanged water.

<2> The mass ratio represented by [mass of hydrophilic fiber] / [mass of water-absorbing polymer] is from 1/5 to 1 / 0.01, preferably from 1/3 to 1 / 0.0. 1 or less, More preferably, it is 1/2 or more and 1 / 0.5 or less, The absorber as described in said <1>.

<3> The water-absorbing polymer has a maximum absorption amount of artificial urine of 24 g / g or more and 40 g / g or less, preferably 25 g / g or more and 38 g / g or less, more preferably 26 g / g or more and 36 g / g or less, particularly The absorbent according to <1> or <2>, preferably 27 g / g or more and 34 g / g or less.
<4> The liquid-absorbing rate of the artificial urine 40 g under a load of 2 kPa under a pressure of 2 kPa in a state where the swelling ratio of the water-absorbing polymer is 60% is 1 g / min to 100 g / min, preferably 3 g / min. The absorption according to any one of <1> to <3>, wherein the absorption is from 5 to 50 g / min, more preferably from 5 to 50 g / min, and particularly preferably from 5 to 30 g / min. body.
<5> The absorbent body according to any one of <1> to <4>, wherein the water-absorbing polymer has a particle ratio of 1% to 10%.

<6> The absorbent body according to any one of <1> to <5>, wherein the water-absorbing polymer contains a soluble content of 1% to 15%.
<7> The absorber according to any one of <1> to <6>, wherein a total area of the recesses in a plan view with respect to an area of the absorber in a plan view is 10% or more and 50% or less.
<8> The total area of the recesses in plan view with respect to the area of the absorber in plan view is more preferably 12% or more and 40% or less, still more preferably 15% or more and 35% or less, and particularly preferably 20%. The absorber according to any one of <1> to <7>, which is not less than 35%.
<9> The absorber according to any one of <1> to <8>, wherein the absorber has a thickness of 0.5 mm to 20 mm.
<10> The absorber according to any one of <1> to <9>, wherein the thickness of the absorber is more preferably from 1 mm to 10 mm, and still more preferably from 1.5 mm to 5 mm.

<11> The depth of the recess is 20% to 100% of the thickness of the absorbent body 10, preferably 25% to 100%, more preferably 30% to 100%, and still more preferably. 50% or more and 100% or less, or 20% or more and 90% or less, preferably 20% or more and 80% or less, more preferably 30% or more and 80% or less, and further preferably 50% or more and 80% or less. The absorber according to any one of <1> to <10>.
<12> The absorbent body according to any one of <1> to <11>, wherein the recess has a width of 1 mm to 20 mm.
<13> The width of the recess is more preferably 2 mm or more and 15 mm or less, further preferably 2 mm or more and 12 mm or less, and particularly preferably 3 mm or more and 10 mm or less, according to any one of the above items <1> to <12>. Absorber.
<14> The absorbent body according to any one of <1> to <13>, wherein the absorbent body has a basis weight at a bottom portion of the recess that is lower than a basis weight at a portion other than the bottom portion of the recess.
<15> The concave portion according to any one of <1> to <14>, wherein a total area of the concave portion having an area of 0.2 cm 2 or more is 50% or more and 100% or less of a total area of all the concave portions. Absorber.

<16> The absorbent body according to any one of <1> to <15>, wherein the water-absorbing polymer is present in the excretion part region at a basis weight of 100 g / m 2 to 500 g / m 2.
<17> The absorbent body according to <16>, wherein the space volume of the concave portion of the excretory part region is 0.8 cm3 or more and 30 cm3 or less.
<18> The water-absorbing polymer present in the excretory region has a water-absorbing polymer particle ratio (fine powder content) of 1 to 10%, more preferably 2 to 9%. Hereinafter, the absorber according to <16> or <17>, more preferably 3% or more and 8% or less.
<19> In any one of the above items <16> to <18>, which satisfies a relationship of “space volume of recess in the excretion part region” ≦ “saturated swelling volume of a water-absorbing polymer of 150 μm or less existing in the excretion part region” The absorber of description.

<20> a liquid-permeable surface sheet disposed on the skin contact surface side;
A liquid-impermeable back sheet disposed on the non-skin contact surface side;
An absorber disposed between the two sheets,
An absorbent article, wherein the absorbent body is the absorbent body according to any one of <1> to <19>.
<21> The absorbent article according to <20>, wherein the recess is present on the surface sheet side of the absorbent body.
<22> The absorbent article according to <20>, wherein the recess is present on the back sheet side of the absorber.
<23> The absorbent article according to any one of <20> to <22>, wherein an intermediate sheet is disposed between the top sheet and the absorber.
<24> The absorbent article according to any one of <20> to <23>, wherein an intermediate sheet is disposed between the back sheet and the absorber.
<25> The absorbent article according to <23> or <24>, wherein a space is present on the absorber side of the intermediate sheet.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to these examples.

I) Preparation of water-absorbing polymer <Synthesis Example 1>
Sodium polyoxyethylene lauryl ether sulfate (trade name) manufactured by Kao Corporation as a dispersant in a 5 L reaction vessel (using anchor blades) equipped with a stirrer, reflux condenser, monomer dropping port, nitrogen gas inlet tube, thermometer Emar 20C) 0.1% [weight of acrylic acid] was charged, and 1600 mL of cyclohexane was added. The mixture was stirred at a rotational speed of 300 r / min under a nitrogen atmosphere, and the temperature was raised to an internal temperature of 77 ° C.
Meanwhile, in a 2 L three-necked flask, 80% acrylic acid manufactured by Toagosei Co., Ltd. and ion-exchanged water were charged, and a 48% caustic soda aqueous solution manufactured by Asahi Glass Co., Ltd. was added dropwise while cooling with ice. 1054 g of an aqueous sodium acrylate solution (72% neutralized product, concentration of about 48%) was obtained. A solution prepared by dissolving 0.25 g of N-acylated glutamic acid soda (trade name Amisoft GS-11F) manufactured by Ajinomoto Co., Inc. in 4.5 g of ion-exchanged water was added to this monomer aqueous solution, and after stirring for a while, 264 g (Hereinafter, monomer aqueous solution A), 264 g (hereinafter, monomer aqueous solution B), and 528 g (hereinafter, monomer aqueous solution C) were divided into three parts.
Next, 0.20 g of 2,2′-azobis (2-amidinopropane) dihydrochloride (trade name V-50) manufactured by Wako Pure Chemical Industries, Ltd., 0.20 g of polyethylene glycol (PEG 6000) manufactured by Kao Corporation. Then, 14 g of ion-exchanged water was mixed and dissolved to prepare an initiator (A) aqueous solution. Moreover, 0.90 g of sodium persulfate manufactured by Wako Pure Chemical Industries, Ltd. was dissolved in 40 g of ion-exchanged water to prepare an initiator (B) aqueous solution. Furthermore, a titanium citrate aqueous solution (citric acid / Ti molar ratio 1.0, solid content 19.0%, Ti amount 0.039% [to acrylic acid]) was prepared.
Monomer A is prepared by adding 7.2 g of initiator (A) aqueous solution to monomer aqueous solution A, and monomer B is prepared by adding 7.2 g of initiator (A) aqueous solution and 1.2 g of titanium citrate aqueous solution to monomer aqueous solution B. Then, 27 g of initiator (B) aqueous solution and 2.5 g of titanium citrate aqueous solution were added to monomer aqueous solution C to prepare monomer C.
The monomer A, the monomer B, and the monomer C, which were allowed to stand for 5 minutes or more, were dropped from the monomer dropping port of the 5 L reactor described above over about 60 minutes in order, and then 13 g of the initiator (B) aqueous solution. Only dripped. 15 minutes after the completion of dropping, a solution obtained by dissolving 0.04 g of ethylene glycol diglycidyl ether (trade name Denacol EX-810) manufactured by Nagase Chemical Industries Ltd. in 10 g of water was added as a crosslinking agent. Thereafter, azeotropic dehydration is performed using a dehydrating tube, the water content of the water-absorbing polymer (hydrogel) is adjusted to 50%, and 0.33 g of ethylene glycol diglycidyl ether (trade name Denacol EX-810) is converted to 10 g of water. The dissolved one was added. Furthermore, azeotropic dehydration was performed until the water content of the water-absorbing polymer (hydrogel) was 30%, and after cooling, cyclohexane was removed and dried under reduced pressure to obtain a water-absorbing polymer. By removing coarse particles with a sieve having an opening of 850 microns, a water-absorbing polymer was obtained.

<Synthesis Example 2>
The water-absorbing polymer of Synthesis Example 1 was mixed with fine powder of 150 μm or less of the water-absorbing polymer synthesized in Synthesis Example 5. The mixing ratio was the water-absorbing polymer of Synthesis Example 1 / the fine powder of 150 μm or less of Synthesis Example 5 = 100/5 weight ratio.
<Synthesis Example 3>
100 parts by weight of the water-absorbing polymer of Synthesis Example 1 and 200 parts by weight of cyclohexane are kept at 70 to 80 ° C. with stirring, and then sodium salt of maleic acid-acrylate copolymer (Socaran CP5 manufactured by BASF, average molecular weight 70,000) 100 parts by weight of a 3.2 mass% aqueous solution of After dehydrating the water-absorbing polymer to a moisture content of 35%, cyclohexane was removed and dried to obtain a water-absorbing polymer.
<Synthesis Example 4>
In Synthesis Example 3, the water-absorbing polymer of Synthesis Example 2 was used in place of the water-absorbing polymer of Synthesis Example 1.

<Synthesis Example 5>
Sodium polyoxyethylene lauryl ether sulfate (trade name) manufactured by Kao Corporation as a dispersant in a 5 L reaction vessel (using anchor blades) equipped with a stirrer, reflux condenser, monomer dropping port, nitrogen gas inlet tube, thermometer Emar 20C) 0.2% [weight of acrylic acid] was charged, and 1600 mL of cyclohexane was added. The mixture was stirred at a rotational speed of 300 r / min under a nitrogen atmosphere, and the temperature was raised to an internal temperature of 77 ° C.
Meanwhile, in a 2 L three-necked flask, 80% acrylic acid manufactured by Toagosei Co., Ltd. and ion-exchanged water were charged, and a 48% caustic soda aqueous solution manufactured by Asahi Glass Co., Ltd. was added dropwise while cooling with ice. 1054 g of an aqueous sodium acrylate solution (72% neutralized product, concentration of about 48%) was obtained. A solution prepared by dissolving 0.25 g of N-acylated glutamic acid soda (trade name Amisoft GS-11F) manufactured by Ajinomoto Co., Inc. in 4.5 g of ion-exchanged water was added to this monomer aqueous solution, and after stirring for a while, 264 g (Hereinafter, monomer aqueous solution A), 264 g (hereinafter, monomer aqueous solution B), and 528 g (hereinafter, monomer aqueous solution C) were divided into three parts.
Next, 0.20 g of 2,2′-azobis (2-amidinopropane) dihydrochloride (trade name V-50) manufactured by Wako Pure Chemical Industries, Ltd., 0.20 g of polyethylene glycol (PEG 6000) manufactured by Kao Corporation. Then, 14 g of ion-exchanged water was mixed and dissolved to prepare an initiator (A) aqueous solution. Moreover, 0.90 g of sodium persulfate manufactured by Wako Pure Chemical Industries, Ltd. was dissolved in 40 g of ion-exchanged water to prepare an initiator (B) aqueous solution. Furthermore, a titanium citrate aqueous solution (citric acid / Ti molar ratio 1.0, solid content 19.0%, Ti amount 0.039% [to acrylic acid]) was prepared.
Monomer A is prepared by adding 7.2 g of initiator (A) aqueous solution to monomer aqueous solution A, and monomer B is prepared by adding 7.2 g of initiator (A) aqueous solution and 1.2 g of titanium citrate aqueous solution to monomer aqueous solution B. Then, 27 g of initiator (B) aqueous solution and 2.5 g of titanium citrate aqueous solution were added to monomer aqueous solution C to prepare monomer C.
The monomer A, the monomer B, and the monomer C, which were allowed to stand for 5 minutes or more, were dropped from the monomer dropping port of the 5 L reactor described above over about 60 minutes in order, and then 13 g of the initiator (B) aqueous solution. Only dripped. 15 minutes after the completion of dropping, a solution obtained by dissolving 0.04 g of ethylene glycol diglycidyl ether (trade name Denacol EX-810) manufactured by Nagase Chemical Industries Ltd. in 10 g of water was added as a crosslinking agent. Thereafter, azeotropic dehydration is performed using a dehydration tube, the water content of the water-absorbing polymer (hydrogel) is adjusted to 50%, and 0.27 g of ethylene glycol diglycidyl ether (trade name Denacol EX-810) is converted to 10 g of water. The dissolved one was added. Furthermore, azeotropic dehydration was performed until the water content of the water-absorbing polymer (hydrogel) was 30%, and after cooling, cyclohexane was removed and dried under reduced pressure to obtain a water-absorbing polymer. By removing coarse particles with a sieve having an opening of 850 microns, a water-absorbing polymer was obtained.

<Synthesis Example 6>
A fine powder of 150 μm or less of the polymer of Synthesis Example 5 synthesized separately from the water-absorbing polymer of Synthesis Example 5 was mixed. The mixing ratio was set to the water-absorbing polymer of Synthesis Example 5 / fine powder of 150 μm or less of Synthesis Example 5 = 100/8 weight ratio.
<Synthesis Example 7>
In Synthesis Example 3, the water-absorbing polymer of Synthesis Example 5 was used in place of the water-absorbing polymer of Synthesis Example 1, and a sodium salt of maleic acid-acrylate copolymer (Socalan CP5 manufactured by BASF, average molecular weight 70,000) ) 9 mass% aqueous solution was used.
<Synthesis Example 8>
Persoft EL (polyoxyethylene (polyoxyethylene (manufactured by Nippon Oil & Fats Co., Ltd.)) as a dispersant in a SUS304 5L reaction vessel (using anchor blades) equipped with a stirrer, reflux condenser, monomer dropping port, nitrogen gas inlet tube and thermometer. EO average added mole number 3) 0.06% [weight of acrylic acid Na] of alkyl ether sulfate Na) and 0.025% [weight of acrylic acid] of Nikkor Chemicals Co., Ltd. Nikkor SMT (acylated taurine Na) And 1600 mL of heptane was added. The mixture was stirred at a rotational speed of 300 r / min under a nitrogen atmosphere, and the temperature was raised to an internal temperature of 90 ° C.
Meanwhile, in a 2 L three-necked flask, 80% acrylic acid manufactured by Toagosei Co., Ltd. and ion-exchanged water were charged, and a 48% caustic soda aqueous solution manufactured by Asahi Glass Co., Ltd. was added dropwise while cooling with ice. 1054 g of an aqueous sodium acrylate solution (72% neutralized product, concentration of about 48%) was obtained.
A solution prepared by dissolving 0.25 g of N-acylated glutamic acid soda (trade name Amisoft GS-11F) manufactured by Ajinomoto Co., Inc. in 3 g of ion-exchanged water was added to this monomer aqueous solution, and after stirring for a while, 264 g, 264 g Divided into 528 g.
Subsequently, 0.041 g of 2,2′-azobis (2-amidinopropane) dihydrochloride (trade name V-50) manufactured by Wako Pure Chemical Industries, Ltd., and 0.20 g of polyethylene glycol (PEG 6000) manufactured by Kao Corporation. Then, 9 g of ion-exchanged water was mixed and dissolved to prepare an aqueous initiator (A) solution. Moreover, 0.49 g of sodium persulfate manufactured by Wako Pure Chemical Industries, Ltd. was dissolved in 10 g of ion-exchanged water to prepare an initiator (B) aqueous solution. Furthermore, a titanium citrate aqueous solution (citric acid / Ti molar ratio 1.0, solid content 19.0%, Ti amount 0.039% [to acrylic acid]) was prepared.
To one of the three divided monomer aqueous solutions (264 g), 2.3 g of the initiator (A) aqueous solution was added (monomer 1). Moreover, 6.9 g of initiator (A) aqueous solution and 1.5 g of titanium citrate aqueous solution were added to another monomer aqueous solution (264 g) divided into three (monomer 2). 10.5 g of initiator (B) aqueous solution and 3.2 g of titanium citrate aqueous solution were added to the remaining three monomer aqueous solutions (528 g) (monomer 3).
Monomer 1, monomer 2, and monomer 3 which were allowed to stand for 5 minutes or more were dropped in order from the monomer dropping port of the 5 L reactor described above over about 60 minutes for polymerization. After completion of the monomer dropping, azeotropic dehydration was performed using a dehydrating tube, and the water content of the water-absorbing polymer (hydrogel) was adjusted to 60%.
Then, what melt | dissolved 0.12 g of ethylene glycol diglycidyl ether (brand name Denacol EX-810) by Nagase Chemical Industries Ltd. in 10 g of water was added as a crosslinking agent. Thereafter, azeotropic dehydration was further performed to adjust the water content of the water-absorbing polymer to 35%. After cooling, heptane was removed by decantation and dried to obtain a water-absorbing polymer. After removing coarse particles with a sieve having an opening of 850 microns, 0.5 parts of Aerosil 200 manufactured by Nippon Aerosil Co., Ltd. was dry blended with 100 parts of the polymer particles to obtain a water-absorbing polymer.

<Synthesis Example 9>
Sodium polyoxyethylene lauryl ether sulfate (trade name) manufactured by Kao Corporation as a dispersant in a 5 L reaction vessel (using anchor blades) equipped with a stirrer, reflux condenser, monomer dropping port, nitrogen gas inlet tube, thermometer Emar 20C) 0.11% [weight of acrylic acid] was charged, and 1600 mL of cyclohexane was added. The mixture was stirred at a rotational speed of 300 r / min under a nitrogen atmosphere, and the temperature was raised to an internal temperature of 77 ° C.
Meanwhile, in a 2 L three-necked flask, 80% acrylic acid manufactured by Toagosei Co., Ltd. and ion-exchanged water were charged, and a 48% caustic soda aqueous solution manufactured by Asahi Glass Co., Ltd. was added dropwise while cooling with ice. 1054 g of an aqueous sodium acrylate solution (72% neutralized product, concentration of about 48%) was obtained. A solution prepared by dissolving 0.18 g of N-acylated glutamic acid soda (trade name: Amisoft GS-11F) manufactured by Ajinomoto Co., Inc. in 3 g of ion-exchanged water was added to this monomer aqueous solution, and after stirring for a while, 264 g (hereinafter referred to as “Amisoft”). Monomer aqueous solution A), 264 g (hereinafter referred to as monomer aqueous solution B), and 528 g (hereinafter referred to as monomer aqueous solution C).
Next, 0.20 g of 2,2′-azobis (2-amidinopropane) dihydrochloride (trade name V-50) manufactured by Wako Pure Chemical Industries, Ltd., 0.20 g of polyethylene glycol (PEG 6000) manufactured by Kao Corporation. Then, 14 g of ion-exchanged water was mixed and dissolved to prepare an initiator (A) aqueous solution. Moreover, 0.49 g of sodium persulfate manufactured by Wako Pure Chemical Industries, Ltd. was dissolved in 10 g of ion-exchanged water to prepare an initiator (B) aqueous solution. Furthermore, a titanium citrate aqueous solution (citric acid / Ti molar ratio 1.0, solid content 19.0%, Ti amount 0.039% [to acrylic acid]) was prepared.
Monomer A is prepared by adding 7.2 g of initiator (A) aqueous solution to monomer aqueous solution A, and monomer B is prepared by adding 7.2 g of initiator (A) aqueous solution and 1.5 g of titanium citrate aqueous solution to monomer aqueous solution B. Then, 10.5 g of the initiator (B) aqueous solution and 3 g of the titanium citrate aqueous solution were added to the monomer aqueous solution C to prepare monomer C.
Monomer A, monomer B, and monomer C, which were allowed to stand for 5 minutes or more, were dropped from the monomer dropping port of the 5 L reaction vessel described above over about 60 minutes in order to polymerize them. After completion of the monomer dropping, azeotropic dehydration is performed using a dehydrating tube, the water content of the water-absorbing polymer (hydrogel) is adjusted to 60%, and ethylene glycol diglycidyl ether (manufactured by Nagase Chemical Industries Co., Ltd.) Trade name Denacol EX-810) 0.18 g dissolved in 10 g of water was added. Thereafter, azeotropic dehydration was further performed, and after cooling, cyclohexane was removed and dried under reduced pressure to obtain a water-absorbing polymer. After removing coarse particles with a sieve having an opening of 850 microns, 0.5 parts of Aerosil 200 manufactured by Nippon Aerosil Co., Ltd. was dry blended with 100 parts of the polymer particles to obtain a water-absorbing polymer.

II) Evaluation of water-absorbing polymer Regarding the water-absorbing polymers of Synthesis Examples 1 to 9, 1) the average particle diameter and fine powder content of the water-absorbing polymer, 2) the maximum amount of artificial urine absorbed by the water-absorbing polymer, and 3) under 2 kPa pressure The liquid flow rate and 4) the content of soluble components were measured by the methods described below, and the results are shown in Table 1.
As shown in Table 1, the water-absorbing polymers of Synthesis Examples 1 to 7 have a wet magnification of 57%, 55%, 60%, 59%, 59%, 55%, and 58%, respectively, and an artificial urine 40 g of 2 kPa was added. The liquid passing speed under pressure is 100 g / min or less.

1) Calculation method of average particle diameter and fine powder content of water-absorbing polymer The average particle diameter is calculated by classifying 100 g of water-absorbing polymer using a sieve in accordance with JIS Z-8801-1982, The average particle size is determined from the mass fraction. The amount of fine powder (water-absorbing polymer having a sieve opening of 150 microns) was also determined from the mass fraction after classification.

2) Method for measuring the maximum absorption amount of artificial urine of water-absorbing polymer The amount of water absorption was measured at room temperature (20 ± 5 ° C.), and 1.00 g of water-absorbing polymer was added to artificial urine (0. 5 ° C.) at room temperature (20 ± 5 ° C.). 9% NaCl aqueous solution (manufactured by Otsuka Pharmaceutical Co., Ltd.) Swelled with 150 mL for 60 minutes, put in a 250 mesh non-woven bag, dehydrated with a centrifuge for 10 minutes at 143G, and measured the total mass (total mass) after dehydration . Then, according to the following equation (1), the amount of artificial urine retained after centrifugal dehydration is measured, and this value is taken as the water absorption amount.

Here, the remaining amount of the nonwoven fabric bag liquid = (the weight of the nonwoven fabric bag after centrifugal dehydration) − (the weight of the nonwoven fabric bag).

3) Method of measuring the liquid flow rate under 2 kPa pressure (a) A cylinder (inner diameter 61 mm) with a wire mesh (100 mesh) is placed in a beaker containing about 300 mL of artificial urine, and 0.80 g of a water-absorbing polymer is quickly added. Soak for 0.5 to 60 minutes, leave to swell, and fill uniformly [see FIG. 6 (a)].
In the state immersed for 60 minutes, the swelling ratio of the water-absorbing polymer is 100%. In order to make the swelling ratio 60% or less, the immersion time of the water-absorbing polymer is within 3 minutes as a guide.
(B) The cylinder containing the swollen water-absorbing polymer is quickly removed from the beaker as shown in FIG.
(C) Quickly place this cylinder on a receiving container (bat), place a glass filter (GI grade, outer diameter 60 mm, thickness 5 mm), place a weight on it, and swell the swollen water-absorbing polymer to 2 kPa. (See FIG. 6C).
(D) 40 g of artificial urine is poured all at once, and the time (S1) from the start of liquid injection until the liquid on the glass filter runs out is measured (see FIG. 6 (d)). The unit is seconds.
The operations (b) to (d) are performed in as short a time as possible, and as a guideline within 15 seconds.
As a blank test, 40 g of artificial urine is poured all at once in the absence of a water-absorbing polymer, and the time (S2) from the start of liquid injection until the liquid on the glass filter runs out is measured.
And the liquid passing speed under 2 kPa pressurization is calculated by the following formula.
Liquid passing speed under pressure of 2 kPa (g / min) = 40 ÷ ((S1-S2) × 60)

The swelling ratio (%) of the water-absorbing polymer when the swelling ratio is less than 100% is the time for immersing the water-absorbing polymer in the artificial urine in “2) Method of measuring the maximum amount of artificial urine absorbed by the water-absorbing polymer” When the amount of absorption at (time t) is V _t , it is expressed by the following formula.
Swelling ratio (%) = (V _t / V∞) × 100
Here, V∞ is the maximum amount of artificial urine absorbed by the water-absorbing polymer.
In addition, when the swelling ratio is less than 100%, the liquid passing speed under 2 kPa pressurization is the same as the above-mentioned time t in the immersion time of the water-absorbing polymer in “3) Measuring method of liquid passing speed under 2 kPa pressurization”. Measured and calculated at

4) Method for measuring soluble content 0.500 g of the water-absorbing polymer was dispersed in 1000 g of deionized water, stirred for 16 hours, and filtered with suction. Next, 10 g of the obtained filtrate was placed in a 100 ml beaker, and 2 ml of 0.05N sodium hydroxide aqueous solution, 5 ml of N / 100 methyl glycol chitosan aqueous solution, and 3 drops of 0.2% toluidine blue aqueous solution were added to the filtrate.
Next, the solution of the beaker was colloidally titrated with an aqueous N / 400 potassium potassium sulfate solution, and the titration point D (ml) was determined with the time when the color of the solution changed from blue to reddish purple as the end point of titration. Moreover, it replaced with 10 g of filtrates, performed the same operation using 10 g of deionized water, and calculated | required titer E (ml) as a blank.
And soluble fraction (mass%) was computed according to following Formula (2) from these titration amounts and the average molecular weight F of the monomer which comprises a water absorbing polymer.

III) Basic production method of absorber <absorber A-1>
A pulp sheet having a basis weight of 50 g / m ² was cut so as to have a width of 100 mm and a length of 375 mm. Further, the water-absorbing polymer was uniformly sprayed so that the basis weight was 80 / m ^2, and the water-absorbing polymer was embedded in the pulp sheet with a roller (sheet 1).
On the other hand, a pulp sheet having a basis weight of 69 g / m ² was cut so as to have a width of 100 mm and a length of 375 mm, and a water-absorbing polymer was uniformly sprayed thereon so that the basis weight was 110 g / m ² . Further, a pulp sheet having a basis weight of 69 g / m ² (horizontal width 100 mm, vertical width 375 mm) is placed thereon, and a water-absorbing polymer is uniformly sprayed thereon so that the basis weight is 110 g / m ^2. A 69 g / m ² pulp sheet (width 100 mm, height 375 mm) was placed. From this sheet, 24 rectangular pieces with h2 = 20 mm and h1 = 30 mm and three rectangular pieces with h2 = 20 mm and h3 = 90 mm are cut out, with a lateral gap e = 5 mm and a vertical interval d = 5 mm, as shown in FIG. It arranged on the sheet | seat 1 like the absorber A in the inside.
This absorber was pressed with mangles. The ratio of [mass of hydrophilic fiber] / [mass of water-absorbing polymer] is 1 / 1.5, the thickness of the absorber is 3.3 mm, and the depth of the recess is 70% of the thickness of the absorber. Met.

<Absorber A-2>
A pulp sheet having a basis weight of 50 g / m ² was cut so as to have a width of 100 mm and a length of 375 mm. On top of that, the water-absorbing polymer was uniformly dispersed so that the basis weight was 80 g / m ^2, and the water-absorbing polymer was embedded in the pulp sheet with a roller (sheet 2).
On the other hand, a pulp sheet having a basis weight of 50 g / m ² was cut so as to have a width of 100 mm and a length of 375 mm, and a water-absorbing polymer was uniformly sprayed thereon so that the basis weight was 110 g / m ² . Further, a pulp sheet having a basis weight of 69 g / m ² (horizontal width 100 mm, vertical width 375 mm) is placed thereon, and a water-absorbing polymer is uniformly sprayed thereon so that the basis weight is 110 g / m ^2. A 69 g / m ² pulp sheet (width 100 mm, height 375 mm) was placed. From this sheet, 24 rectangular pieces with h2 = 20 mm and h1 = 30 mm and three rectangular pieces with h2 = 20 mm and h3 = 90 mm are cut out, with a lateral gap e = 5 mm and a vertical interval d = 5 mm, as shown in FIG. The sheet | seat 2 was produced on the sheet | seat 2 like the absorber A in the inside.
Further, a pulp sheet having a basis weight of 50 g / m ² was cut out at a width of 5 mm, and was made to fit into the concave portion of the sheet 2 using a drawing tweezers.
This absorber was pressed with mangles. The ratio of [mass of hydrophilic fiber] / [mass of water-absorbing polymer] is 1 / 1.5, the thickness of the absorber is 3.0 mm, and the depth of the recess is 38% of the thickness of the absorber. Met.

<Absorber B>
A pulp sheet having a basis weight of 50 g / m ² was cut so as to have a width of 100 mm and a length of 375 mm. On top of that, the water-absorbing polymer was uniformly sprayed so that the basis weight was 90 g / m ² . Thereon, placing a pulp sheet having a basis weight of 57 g / m ² (width 100 mm, vertical width 375 mm), basis weight thereon was uniformly sprayed water-absorbing polymer such that the 91g / m ^2. Further thereon, placing a pulp sheet having a basis weight of 57 g / m ² (width 100 mm, vertical width 375 mm), basis weight thereon is uniformly sprayed water-absorbing polymer such that the 91g / m ^2, the basis weight A sheet 3 was prepared by placing a 57 g / m ² pulp sheet (width 100 mm, height 375 mm).
From the sheet 3, as in the absorbent body B in FIG. 7, twelve concave portions with f = 5 mm and h4 = 50 mm and three concave portions with g = 10 and h5 = 50 mm are formed as h7 = 20 mm, h8 = 15 mm, h6 = The sheet 4 was cut out at intervals of 25 mm (h9 = 50 mm). A sheet of pulp sheet having a basis weight of 50 g / m ² cut into 12 recesses of f = 5 and h4 = 50 mm of this sheet 4 having a basis weight of 50 g / m ² was cut into 5 mm width and blended with a tweezers, and water was absorbed at the bottom of the recess. 0.5 g of the conductive polymer was uniformly sprayed (16.7 g / m ² ).
This absorber was pressed with mangles. The ratio of [mass of hydrophilic fiber] / [mass of water-absorbing polymer] is 1 / 1.5, the thickness of the absorber is 3.0 mm, and the depth of the recess is 100% of the thickness of the absorber. (3 recesses with g = 10 mm and h5 = 50 mm) and 70% (12 recesses with f = 5 mm and h4 = 50 mm).

<Absorber C>
Between 4 layers of 50g / m ² basis weight pulp sheet, water-absorbing polymer is sprayed at a basis weight of 80g / m ² for each layer (thus, 3 layers of water-absorbing polymer), so that the width is 100mm and the length is 375mm. Cut into.
This absorber was pressed with mangles. The ratio of [mass of hydrophilic fiber] / [mass of water-absorbing polymer] was 1 / 1.5, and the thickness of the absorber was 2.9 mm.

IV) Absorbent Production Method <Example 1>
Absorbent body A-1 was produced using the water-absorbing polymer of Synthesis Example 1.
This absorbent body was wrapped with a tissue paper (not shown) having a basis weight of 16 g / m ² coated with a hot melt agent, the hot melt agent was melted with an iron, and the absorbent body and the tissue paper were joined. This was arrange | positioned between the surface sheet and the back sheet (a recessed part is on the clothing side), and the absorbent article was obtained. For the top sheet that is the skin contact surface, use the surface material of the brand name Marys manufactured by Kao Co., Ltd. For the liquid-impermeable back sheet, use the back sheet of the brand name of Kao Co., Ltd. It was.

<Example 2>
Absorbent body A-1 was produced using the water-absorbing polymer of Synthesis Example 5.
This absorbent body was wrapped with a tissue paper (not shown) having a basis weight of 16 g / m ² coated with a hot melt agent, the hot melt agent was melted with an iron, and the absorbent body and the tissue paper were joined. This was arrange | positioned between the surface sheet and the back surface sheet (a recessed part is on the skin side), and the absorbent article was obtained. For the top sheet that is the skin contact surface, use the surface material of the brand name Marys manufactured by Kao Co., Ltd. For the liquid-impermeable back sheet, use the back sheet of the brand name of Kao Co., Ltd. It was.

<Example 3>
Absorbent body A-2 was produced using the water-absorbing polymer of Synthesis Example 5.
This absorbent body was wrapped with a tissue paper (not shown) having a basis weight of 16 g / m ² coated with a hot melt agent, the hot melt agent was melted with an iron, and the absorbent body and the tissue paper were joined. This was arrange | positioned between the surface sheet and the back surface sheet (a recessed part is on the skin side), and the absorbent article was obtained. For the top sheet that is the skin contact surface, use the surface material of the brand name Marys manufactured by Kao Co., Ltd. For the liquid-impermeable back sheet, use the back sheet of the brand name of Kao Co., Ltd. It was.

<Example 4>
In Example 1, the water-absorbing polymer of Synthesis Example 2 was used in place of the water-absorbing polymer of Synthesis Example 1.
<Example 5>
In Example 1, the water-absorbing polymer of Synthesis Example 4 was used in place of the water-absorbing polymer of Synthesis Example 1.
<Example 6>
In Example 1, the water-absorbing polymer of Synthesis Example 3 was used instead of the water-absorbing polymer of Synthesis Example 1, and the concave portion of the absorbent body was on the skin side.

<Example 7>
In Example 2, the absorber B was used instead of the absorber A-2.
<Example 8>
In Example 7, the water-absorbing polymer of Synthesis Example 6 was used in place of the water-absorbing polymer of Synthesis Example 5.
<Example 9>
In Example 7, the water-absorbing polymer of Synthesis Example 7 was used in place of the water-absorbing polymer of Synthesis Example 5.

<Comparative Example 1>
In Example 1, the water-absorbing polymer of Synthesis Example 9 was used in place of the water-absorbing polymer of Synthesis Example 1.
<Comparative example 2>
In Example 1, the water-absorbing polymer of Synthesis Example 8 was used in place of the water-absorbing polymer of Synthesis Example 1.
<Comparative Example 3>
In Example 7, the water-absorbing polymer of Synthesis Example 8 was used in place of the water-absorbing polymer of Synthesis Example 5.
<Comparative example 4>
In Example 1, the absorber C was used instead of the absorber A-1.

V) Evaluation of Examples and Comparative Examples The absorbent articles manufactured in Examples and Comparative Examples were subjected to the following evaluation tests, and the results are shown in Tables 2 and 3. Moreover, about the absorbent article of an Example and a comparative example, in Table 2, the swelling volume of the fine powder in the urination part area | region, the space volume of a recessed part, those ratios, etc. were shown collectively.
1) <Measurement of absorption capacity of absorbent article>
The evaluation method regarding the absorption capacity of the absorbent article will be described below.
An absorbent article prepared on an acrylic plate tilted at 20 degrees is placed (the abdomen end edge is on the lower side), and an acrylic plate and a weight are placed on the absorbent article and a load of 2.0 kPa is applied to the entire absorbent article. . In this state, a fixed amount of artificial urine colored at a position of 150 mm from the upper end of the absorbent article is repeatedly injected at regular intervals, and the amount of injection until it leaks from the lower end of the absorber is determined. Compare. Use a test atmosphere at room temperature (20 ± 5 ° C.) and artificial urine at room temperature (20 ± 5 ° C.).
The relative value when the absorption capacity of Comparative Example 4 is 1.0 is calculated using the following calculation formula.
Absorption capacity (relative value) = (absorption capacity of sample) / (absorption capacity of comparative example 2)

2) <Measurement of liquid return amount of absorbent article>
A method for measuring the liquid return amount of the absorbent article will be described. As an example, a case of an infant paper diaper (M size) will be described.
An acrylic cylinder having an inner diameter of 35 mm is placed in the longitudinal direction of the absorbent article from the ventral side edge portion at 150 mm and in the width direction at the center, and 40 g of colored artificial urine is applied to the entire absorbent article while applying a load of 2.0 kPa. Inject while maintaining the liquid to a height of 10 mm. Note that an acrylic plate having a size covering the entire absorbent article is provided at the lowermost part of the cylinder. After 10 minutes from the start of absorption, 40 g is injected again. This operation is repeated twice more, and a total of 160 g of artificial urine is injected. The test atmosphere temperature was room temperature (20 ± 5 ° C.), and the artificial urine was room temperature (20 ± 5 ° C.).
Ten minutes after the completion of injection, filter paper No. A stack of 10 sheets of 4A (100 mm × 100 mm, mass measurement W1) is placed on the absorbent article around the injection point.
A pressure of 3.5 kPa was applied through an acrylic plate having a thickness of 5 mm and 100 mm × 100 mm, the mass of the filter paper was measured after 2 minutes (W2), and the liquid return amount was calculated according to the following equation.
Liquid return amount (g) = mass of filter paper after pressurization (W2) −mass of first filter paper (W1)
The relative value when the liquid return amount of Comparative Example 4 is 1.0 is calculated using the following calculation formula.
Liquid return amount (relative value) = (Liquid return amount of sample) / (Liquid return amount of Comparative Example 2)

3) <Measurement of pore water content of absorbent article>
After measuring the liquid return amount in 2), cut the liquid return amount measurement site with scissors. The weight W3 of this liquid return amount measurement site is measured. Next, this is put into a 250-mesh non-woven bag, dehydrated at 143 G for 10 minutes with a centrifuge, and the mass (W4) of the liquid return amount measurement site after dehydration is measured. Then, pore water is calculated according to the following equation.
Pore water amount at liquid return amount measurement site = W3−W4 + liquid return amount

  As shown in the results of Tables 2 and 3, the absorbent articles of Examples 1 to 6 have an absorption capacity equal to or greater than that of Comparative Examples 1, 2, and 4. This is because the liquid was diffused in a wide range by the recesses, and a water-absorbing polymer with weak cross-linking (which can absorb more liquid) could be used. In addition, the absorbent articles of Examples 1 and 2 have less interstitial water in the excretory region and less liquid return than Comparative Examples 1, 2 and 4. This is because the liquid was diffused in a wide range by the recesses, and a water-absorbing polymer with weak cross-linking (which can absorb more liquid) could be used. The absorbent articles of Examples 3 to 6 have a smaller liquid return amount than Comparative Examples 2 and 4, although there is more pore water in the excretion region. In the absorbent articles of Examples 3 to 6, the recesses are designed to be easily filled as compared with Examples 1 and 2, and the absorption capacity is almost the same as Comparative Examples 2 and 4, but the gel blocking of the water-absorbing polymer Therefore, even if there is a lot of pore water, it is difficult for the liquid to return.

On the other hand, the absorbent articles of Examples 7 to 9 have an absorption capacity equal to or greater than that of Comparative Examples 3 and 4. This is because the liquid diffused in a relatively wide range due to the recesses, and a water-absorbing polymer with weak crosslinking (which can absorb more liquid) could be used. Moreover, although the absorbent articles of Examples 7-9 have more pore water in the excretion part area | region than Comparative Examples 3 and 4, the liquid return amount is small. The recesses are easily filled, and the gel-blocking of the water-absorbing polymer prevents the liquid from returning even if there is a lot of pore water.
From these, by using a water-absorbing polymer with weak cross-linking that causes gel blocking at a low swelling ratio in an absorbent body having a recess, gel blocking is repeated until the recess is filled with the swollen water-absorbing polymer in repeated excretion. Excellent action of diffusing liquid while suppressing, exhibiting high absorbency, causing depression when the recess is filled with swollen water-absorbing polymer, and exhibiting low liquid return without permeating pore water to the skin side It turns out that there is an effect.

10, 10 ', 10 "Absorber 11, 11A, 11B Concave part 12 Block-like convex part (parts other than the concave part)
21 hydrophilic fiber 22 water-absorbing polymer 50, 50A, 50B disposable diaper (absorbent article)

Claims (16)

An absorbent body having a hydrophilic fiber and a water-absorbing polymer, the absorbent body having a recess having a depth of 20% to 100% of the thickness of the absorbent body,
The mass ratio represented by [mass of hydrophilic fiber] / [mass of water-absorbing polymer] in the absorber is 1/5 or more and 1 / 0.01 or less,
The water-absorbing polymer is an absorbent having a swelling ratio of 60% or less and a passing rate of 40 g of artificial urine having the following composition under a pressure of 2 kPa of 100 g / min or less.
Artificial urine composition: 1.94% urea, 0.80% sodium chloride, 0.06% calcium chloride, 0.11% magnesium sulfate, 0.085% ammonium dihydrogen phosphate, 0.015% diammonium hydrogen phosphate , 96.99% ion-exchanged water.   The absorber according to claim 1, wherein the water-absorbing polymer has a ratio of particles having a particle size of 150 microns or less of 1% or more and 10% or less.   The absorber according to claim 1 or 2, wherein the water-absorbing polymer contains a soluble content of 1% or more and 15% or less.   The absorber according to any one of claims 1 to 3, wherein a total area of the recesses in a plan view with respect to an area of the absorber in a plan view is 10% or more and 50% or less.   The absorber of any one of Claims 1-4 whose thickness of the said absorber is 0.5 mm or more and 20 mm or less.   The width | variety of the said recessed part is 1 mm or more and 20 mm or less, The absorber of any one of Claims 1-5.   The said absorber is an absorber of any one of Claims 1-6 in which the basic weight in the bottom part of the said recessed part is lower than the basic weight in parts other than the bottom part of this recessed part. The absorber according to any one of claims 1 to 7, wherein the recess has a total area of recesses having an area of 0.2 cm ² or more and 50% or more and 100% or less of a total area of all the recesses. The absorbent body according to any one of claims 1 to 8, wherein the water-absorbing polymer is present in the excretion region in a basis weight of 100 g / m ² or more and 500 g / m ² or less.   The absorbent body according to any one of claims 1 to 9, which satisfies a relationship of "space volume of recess in excretory part region" ≤ "saturated swelling volume of water-absorbing polymer of 150 microns or less existing in excretory part region". A liquid-permeable surface sheet disposed on the skin contact surface side;
A liquid-impermeable back sheet disposed on the non-skin contact surface side;
An absorber disposed between the two sheets,
The absorbent article whose absorber is an absorber given in any 1 paragraph of Claims 1-10.   The absorptive article according to claim 11 in which said crevice exists in said surface sheet side of said absorber.   The absorptive article according to claim 11 in which said crevice exists in said back sheet side of said absorber.   The absorbent article according to any one of claims 11 to 13, wherein an intermediate sheet is disposed between the top sheet and the absorber.   The absorbent article according to any one of claims 11 to 14, wherein an intermediate sheet is disposed between the back sheet and the absorber.   The absorbent article according to claim 14 or 15, wherein a space is present on the absorber side of the intermediate sheet.