JP5498152B2 - Absorber and absorbent article - Google Patents

Description

  The present invention relates to an absorbent body used for absorbent articles such as sanitary napkins and disposable diapers.

  Absorbent articles that retain excretory fluid are incorporated in absorbent articles such as sanitary napkins and disposable diapers, and those containing fibers such as pulp fibers and absorbent polymer particles are known as the absorbent bodies. . This type of absorber is required to have practically sufficient liquid absorbability and to prevent the absorbent polymer particles from dropping off, and various techniques have been proposed to meet such a demand.

  For example, Patent Document 1 includes an absorbent composite including a fiber matrix including fibers and absorbent polymer particles, and the absorbent polymer particles are located in the voids in the fiber matrix and are expandable in the voids. Is described. In this fiber matrix, a large number of voids containing absorbing polymer particles are formed.

  Patent Document 2 describes an absorbent structure in which absorbent polymer particles are substantially uniformly distributed in a continuous region between a first layer and a second layer. In this continuous region, a large number of areas are formed which are formed by thermal bonding between the first layer and the second layer and do not contain absorbent polymer particles, and the areas are surrounded by a large number of absorbent polymer particles. ing.

  Patent Document 3 includes a fiber material, first absorbent polymer particles, and second absorbent polymer particles having a particle diameter larger than that of the first absorbent polymer particles. An absorptive sheet is described, at least partly having voids formed around it by second absorbent polymer particles. The absorbent sheet described in Patent Document 3 is configured by locally arranging the first and second absorbent polymer particles between two fiber webs, and accommodates the first and second absorbent polymer particles. The plurality of voids are not independent of each other like the numerous voids described in Patent Document 1, but are continuous with each other to substantially form a storage space for one absorbent polymer particle.

JP-T-2002-529168 Japanese National Patent Publication No. 11-503594 JP 2008-161301 A

  In the absorbent composite described in Patent Document 1, the volume of the voids that accommodate the absorbent polymer particles may exceed the swellable magnification of the absorbent polymer particles, and in that case, the absorbent polymer particles in the voids are absorbed. The liquid that has not been left remains in the gap, and as a result, liquid leakage or liquid return may occur. Regarding the voids, Patent Document 1 does not describe providing a group of voids having different volumes, and the absorbent composite described in Patent Document 1 is composed of a large number of voids having a substantially constant volume. It only has one group. Therefore, the absorptive complex described in Patent Document 1 may not be able to efficiently absorb a highly viscous liquid such as menstrual blood or loose stool.

  Further, in the absorbent structure described in Patent Document 2, the absorbent polymer particles are substantially uniformly distributed, and as described in Patent Document 1, the absorbent polymer particles are individually accommodated in the voids. Since it does not take a form, the absorbent polymer particles swollen by liquid absorption are in close contact with each other, which may cause a gel blocking phenomenon that hinders passage and diffusion of the liquid, and there is a concern about a decrease in absorption performance. In addition, the absorbent sheet described in Patent Document 3 is not as close to the absorbent polymer particles as the absorbent structure described in Patent Document 2, but does not have voids of individual absorbent polymer particles. Therefore, there is room for improvement in terms of absorption performance.

  Accordingly, an object of the present invention is to provide an absorbent body and an absorbent article that are excellent in the drawability and retention of liquid and that can exhibit excellent absorbency even for highly viscous liquids.

  The present invention is an absorbent body comprising a wet papermaking containing pulp fibers as a main fiber, wherein a large number of absorbent polymer particles are dispersed inside the wet papermaking, and the inside of the wet papermaking In addition, a plurality of void groups are formed which are surrounded by the constituent fibers of the wet papermaking body and contain one or more absorbent polymer particles, and the plurality of void groups are mutually void The above-mentioned problems are solved by providing an absorbent body having different average volumes.

  Moreover, this invention is an absorbent article which comprises the surface sheet which forms a skin contact surface, the back sheet which forms a non-skin contact surface, and the said substantially vertically long said absorber interposed between both sheets. The absorber includes a first void group having a relatively large average volume of the voids and a second void group having a relatively small average volume. The group of 1 voids solves the above problem by providing an absorbent article disposed on the skin contact surface side in the center in the width direction of the absorbent body.

  Further, the present invention comprises a top sheet that forms a skin contact surface, a back sheet that forms a non-skin contact surface, and a substantially vertically long absorber disposed between both sheets, and is worn when worn. An absorbent article having an abdominal side portion disposed on the stomach side and a back side portion disposed on the back side in the longitudinal direction, wherein the absorbent body has a relatively large average volume of the gap portion A first gap group and a second gap group having a relatively small average volume, and the first gap group is biased toward the dorsal side. The said subject is solved by providing the absorbent article.

  According to the present invention, it is possible to provide an absorbent body and an absorbent article that are excellent in liquid drawability and retention, and that can exhibit excellent absorbency even for highly viscous liquids.

FIG. 1 is a perspective view showing a skin contact surface side (surface sheet side) of a sanitary napkin that is a first embodiment of the absorbent article of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section taken along line II of FIG. FIG. 3 is a perspective view of an absorber used in the napkin shown in FIG. FIG. 4 is a cross-sectional view schematically showing a cross section taken along line II of FIG. FIG. 5A and FIG. 5B are views corresponding to FIG. 4 schematically showing another embodiment of the absorbent body of the present invention. FIG. 6A to FIG. 6D are plan views schematically showing still other embodiments of the absorbent body of the present invention. FIG. 7: is a top view which partially fractures | ruptures and shows the skin contact surface side (surface sheet side) in the expansion | deployment state of the disposable diaper which is 2nd Embodiment of the absorbent article of this invention. FIG. 8 is a cross-sectional view schematically showing a cross section taken along line II of FIG. FIG. 9 is a perspective view of an absorber used in the diaper shown in FIG. 10 is a cross-sectional view schematically showing a cross section taken along line II of FIG. 11 is a cross-sectional view schematically showing a cross section taken along line II-II in FIG. FIG. 12 is a view corresponding to FIG. 9 schematically showing still another embodiment of the absorbent body of the present invention. FIG. 13 is a schematic diagram showing an instrument used for evaluating the permeability of pseudo-soft stool.

  Hereinafter, the absorbent body of the present invention will be described together with the absorbent article of the present invention including the absorbent body based on preferred embodiments thereof with reference to the drawings. The sanitary napkin as 1st Embodiment of the absorbent article of this invention is shown by FIGS. 1-4. The napkin 1 according to the first embodiment includes a liquid-permeable top sheet 2 that forms a skin contact surface, a liquid-impermeable or liquid-permeable back sheet 3 that forms a non-skin contact surface, and both sheets 2. , 3 is provided with a liquid-retaining absorber 4 interposed between the two. As shown in FIG. 3, the absorber 4 has a shape that is long in one direction (substantially rectangular shape), and is substantially vertically long. The absorbent body 4 is arranged at the center in the width direction (Y direction in the figure) of the napkin 1 with its longitudinal direction coinciding with the napkin longitudinal direction (X direction in the figure).

  In the present specification, the skin contact surface is a surface of the absorbent article or a component thereof that faces the wearer's skin when the absorbent article is worn, and the non-skin contact surface is the absorbent article. Alternatively, it is a surface of the member that is directed to the side opposite to the skin side (clothing side) when the absorbent article is worn. Moreover, a longitudinal direction is a direction along the long side of an absorbent article or its structural member, and a width direction is a direction orthogonal to this longitudinal direction. In the figure, the direction indicated by reference sign X is the longitudinal direction of the napkin 1 (article longitudinal direction), and the direction indicated by reference sign Y is the width direction of the napkin 1 (article width direction). The longitudinal direction of the absorbent body 4 coincides with the longitudinal direction of the napkin 1, and the width direction of the absorbent body 4 coincides with the width direction of the napkin 1.

  As shown in FIG. 2, the top sheet 2 is disposed on the skin contact surface side of the absorbent body 4, and the back sheet 3 is disposed on the non-skin contact surface side of the absorbent body 4. Each of the top sheet 2 and the back sheet 3 can be made of the same material as that conventionally known. As the top sheet 2, for example, a hydrophilic nonwoven fabric or an apertured film is used. For example, a liquid-impermeable or liquid-impermeable film sheet or the like is used, and the liquid-impermeable film sheet may have water vapor permeability.

  The skin 4 and the non-skin contact surface of the absorbent body 4 (wet papermaking body 40) are covered with two liquid permeable core wrap sheets 6 on the upper and lower sides. Thus, covering the absorbent body 4 with the core wrap sheet 6 is effective for improving the shape stability of the absorbent body 4 and preventing the absorbent polymer particles contained in the absorbent body 4 from falling off. As the core wrap sheet 6, for example, paper such as tissue paper, various non-woven fabrics, apertured films, and the like can be used. The top sheet 2 and the back sheet 3 and the core wrap sheet 6 are joined to each other by a pattern-coated adhesive (hot melt adhesive or the like) such as dots, spirals, and stripes.

  The top sheet 2 and the back sheet 3 have dimensions larger than those of the absorbent body 4, extend from the peripheral edge of the absorbent body 4, and are joined to each other by heat sealing or the like at the ends of the extended sections. 7 is formed. Moreover, the top sheet 2 and the back sheet 3 extend outward in the width direction from both side edges along the longitudinal direction (X direction in the drawing) of the absorber 4 to form a pair of flap portions. Each of the pair of flap portions further extends outward in the width direction (Y direction in the figure) at a portion (exhaust portion facing portion) that opposes the excretion portion of the wearer of the napkin 1, and the pair of wing portions 8, 8 is formed. Each wing portion 8 is used with its non-skin contact surface folded back to the outer surface side of the crotch portion of an underwear such as shorts when the napkin 1 is worn. An adhesive portion (not shown) for fixing 1 to the underwear is provided. An adhesive portion (not shown) for fixing the napkin 1 to the underwear is also provided on the non-skin contact surface of the back sheet 3.

  On the skin contact surface of the napkin 1 (skin contact surface of the topsheet 2), a pair of leak-proof grooves 9, 9 extending in the longitudinal direction of the napkin 1 are formed on both left and right side portions along the longitudinal direction. . The leak-proof groove 9 is formed by consolidating and integrating the top sheet 2 and the absorbent body 4 from the top sheet 2 side by pressing means such as embossing. The leak-proof groove 9 has a substantially symmetrical shape with respect to the vertical center line of the napkin 1. The pair of leak-proof grooves 9 and 9 are connected to each other at the center in the width direction of the napkin 1 by the front and rear ends thereof, thereby forming a closed shape as a whole. By forming the leak-proof grooves 9 and 9, body fluid and the like flowing outward in the width direction of the napkin 1 are blocked, and leakage (lateral leakage) from the side of the napkin 1 is effectively prevented. In addition, as will be described later, the formation position of the leak-proof groove 9 is appropriately set in relation to the arrangement positions of the plurality of gap groups 40A and 40B formed in the absorbent body 4 (wet papermaking body) 40. Thereby, the fitting property with respect to the wearer's body of the napkin 1 can be improved, and it becomes possible to reduce a leak and the uncomfortable feeling at the time of wear.

  The absorbent body 4 includes a wet papermaking body 40 containing pulp fibers as main fibers, and a large number of absorbent polymer particles 42 are dispersedly arranged inside the wet papermaking body 40 as shown in FIG. As will be described later, the wet papermaking body 40 is a fiber assembly produced by using a conventionally known wet papermaking method, and includes pulp fibers (not shown) and a large number of absorbent polymer particles 42 and an absorbent polymer. It is obtained by drying a wet fiber web (wet fiber web) in which the particles 42 are swollen by absorbing the liquid.

  Inside the wet papermaking body 40, a large number of voids 43 surrounded by the constituent fibers of the wet papermaking body 40 and containing one or more absorbent polymer particles 42 are formed. The absorbent polymer particles 42 are three-dimensionally dispersed in the entire wet papermaking body 40 together with the voids 43 that accommodate the absorbent polymer particles 42. As will be described later, the void 43 is formed by utilizing the swelling of the absorbent polymer particles 42 in the dry state due to liquid absorption and the reduction due to the drying of the absorbent polymer particles 42 in the swollen state. Is close to the swollen shape of one or more absorbent polymer particles contained in the void. Therefore, the gap 43 is different in shape, size (volume), and the like from a normal inter-fiber gap formed without using the swelling / reduction of the absorbent polymer particles. In FIG. 4, one absorbent polymer particle 42 is accommodated in one void portion 43, but the number of absorbent polymer particles accommodated in one void portion is not particularly limited, and is two or more. May be. In addition, the number of the absorbent polymer particles accommodated in the voids may be different from each other in the plurality of voids.

  The large number of gaps 43 are not substantially the same in size (volume) macroscopically (the volume of the large number of gaps 43 is not within a specific narrow range), and the volume is relatively small. It is classified into a large first gap 43a and a second gap 43b having a relatively small volume. A large number of both void portions 43a and 43b are formed inside the wet papermaking body 40. From the first void group 40A composed of a large number of first void portions 43a and the large number of second void portions 43b. The second void group 40B exists. The first void group 40A and the second void group 40B are different from each other in average volume of a large number of void portions 43 constituting each void group. Incidentally, the “void group (group of void parts)” referred to here is a wet papermaking body including a large number of voids and constituent members of the wet papermaking body such as fibers located around each of the voids. It means an area that can be physically removed. The volume of the gap 43 can be measured by the following method.

<Method for measuring volume of gap>
Prior to measurement, as a pretreatment, the wet wet papermaking body (absorbent body) to be measured is placed on a flat table, and a load of 24.5 kPa is applied from above to the wet papermaking body for 12 hours. Multiply continuously. By this pretreatment, the thickness of the wet papermaking body can be recovered and the influence of wrinkles and the like can be removed. Using a microscope (Keyence Co., VH-8000), a cut surface along the longitudinal direction of the pretreated wet papermaking (cut surface along the longitudinal direction of the absorbent article in which the absorbent body was incorporated) was used. A double magnified image is divided and captured and captured as image data. The image data composed of a plurality of divided images thus obtained is processed using image analysis processing software (Image-Pro plus, Media Cybernetics), and each of the plurality of divided images is surrounded by the constituent fibers of the wet papermaking body. And the area of the space | gap part in which the 1 or more absorption polymer particle is accommodated is calculated. Next, each void is approximated to a virtual circle having the same area as the calculated area of the void, and from the radius of the obtained virtual circle, the void is regarded as a sphere, Calculate the volume.

  The average volume of the voids in the void group is calculated as follows using the volume of each void calculated according to the above <Method for measuring volume of voids>. In the void group, as the class width, the absolute value of the difference between the maximum void volume value and the minimum void volume value is divided into 20 levels, and the individual void portions thus obtained are divided. Arrange the volume into a histogram. Then, by summing the rank and frequency for each peak and taking the sum, the total volume (total volume) of all the voids in the void group is calculated, and the total volume is the total number of voids constituting each peak. To calculate the average volume of the voids in the void group.

In addition, it can be evaluated, for example by the following method, whether or not a plurality of void groups having different average volumes of voids are formed in the wet papermaking body (absorber). The wet papermaking body is divided into a plurality of regions, and the average volume of the voids is calculated by the above procedure for each region. As a method of dividing the wet papermaking body into a plurality of regions, for example, an absorbent article in which the wet papermaking object to be measured is incorporated is divided into three equal parts in the longitudinal direction and the width direction, respectively. Can be divided into a total of nine regions. If two zones adjacent to each other in the longitudinal direction or the width direction of the article have a difference in average volume of the gaps of less than 0.005 mm ³ , the two areas have the same average volume of the gaps and are identical. If the difference is 0.005 mm ³ or more, it is determined that the two regions have different average volumes of the voids and belong to different void groups. Or, in the two grades of the gap portion used in calculating the average volume of the void portion in the 20 steps, when the rank is 5 steps or more away, the two regions are the average volume of the void portion. Are different and belong to different gap groups. The above operation is repeated for all areas.

The ratio of the average volume V1 of the first gap group 40A having a relatively large average volume of the gaps to the average volume V2 of the second gap group 40B having a relatively small average volume of the gaps (V1 / V2) is preferably 1.5 to 100, more preferably 5 to 50. The average volume V1 is preferably 0.01 to 0.2 mm ³ , more preferably 0.03 to 0.15 mm ³ .

  As shown in FIGS. 3 and 4, the first gap group 40 </ b> A is arranged on the skin contact surface side in the center portion of the wet papermaking body 40 in the width direction (Y direction in the drawing). More specifically, the first gap group 40A has a rectangular shape that is narrower than the wet papermaking body 40 and has a shorter length in the longitudinal direction in plan view, and the width direction of the wet papermaking body 40 and It is biased to the skin contact surface side of the central part in the longitudinal direction. Further, the first gap group 40A has a thickness smaller than that of the wet papermaking body 40, and therefore is not exposed to the non-skin contact surface side of the wet papermaking body 40. A region other than the first gap group 40A in the wet papermaking body 40 is a second gap group 40B. 40 A of 1st space | gap groups are buried in 2nd space | gap group 40B in the state which exposed the skin contact surface, and the space | gap group 40A and space | gap which form the skin contact surface of the wet papermaking 40 The skin contact surface of each group 40B is on the same plane, and the skin contact surface of the wet papermaking body 40 is flat. The location of the first gap group 40A in the wet papermaking body 40 substantially coincides with the excretory part-facing part of the napkin 1, and the gap group 40A has a pair of wing parts 8 and 8 (see FIG. 1) in the napkin 1. Arranged between.

  The dimensions of each part of the wet papermaking according to the present invention vary depending on the type and application of the absorbent article in which it is incorporated. In the case of a sanitary napkin, the ratio (W2 / W1) between the width W1 of the wet papermaking body 40 (see FIG. 3) and the length W2 of the first gap group 40A in the width direction is preferably 0. .4 to 0.8, more preferably 0.55 to 0.7. Further, the ratio (T2 / T1) between the thickness T1 of the wet papermaking body 40 (see FIG. 4) and the thickness T2 of the first gap group 40A is preferably 0.3 to 1.0, more preferably 0.00. 4 to 0.8. The width W1 of the wet papermaking body 40 is preferably 50 to 100 mm, more preferably 60 to 80 mm, and the thickness T1 of the wet papermaking body 40 is preferably 0.3 to 5 mm, more preferably. 1 to 3 mm.

  Thus, in the wet papermaking body 40 (absorbent body 4), two void groups 40A and 40B having different average volumes of the void portions are formed, and the two void groups 40A and 40B are in a specific form. Since it is arranged, the wet papermaking body 40 is excellent in the drawability and retention of the liquid and can exhibit excellent absorbency even for a highly viscous liquid. That is, since the first void portion 43a constituting the first void group 40A is a void portion having a relatively large volume, even if the absorbent polymer particles 42 are accommodated in the void portion 43a, the first void portion 43a is still relatively large. It has a space (part where there is no fiber etc.). Due to the presence of this space, the first gap 43a can quickly absorb the liquid, and can take in and fix a highly viscous excretory liquid such as menstrual blood or loose stool. Since the movement of the high-viscosity excretion liquid in the wet papermaking body 40 is mainly due to gravity, the high-viscosity excretion liquid is easily taken into the first gap portion 43a having a relatively large space.

  On the other hand, since the second void portion 43b constituting the second void group 40B is a void portion having a relatively small volume, the space (fibers or the like) not occupied by the absorbent polymer particles 42 in the void portion 43b. (The portion where no is present) is smaller than that of the first gap 43a. Therefore, the second gap portion 43b is excellent in the intake of low-viscosity excretory fluid (urine, plasma, moisture, etc.), and has a small flow space even when the highly viscous excretory fluid enters the inside. Therefore, it is difficult to diffuse to other parts. Since the movement of the low-viscosity excretion fluid in the wet papermaking body 40 is mainly due to capillary force, the low-viscosity excretion fluid is easily taken into the second gap portion 43b having a relatively small space.

  And in 1st Embodiment, the skin contact surface of the width direction center part (the said excretion part opposing part) of the wet papermaking body 40 which is a part which receives excretion liquid first in the wet papermaking body 40 (absorbent body 4). By disposing the first gap group 40A on the side, the excretory liquid is quickly absorbed into the wet papermaking body 40, and the highly viscous excretion liquid is absorbed into the first gap group 40A (first gap part 43a). It is taken in and fixed to suppress the diffusion of highly viscous excretory fluid to other parts. Moreover, the low-viscosity excretion fluid that has passed through the first gap group 40A is taken into the second gap group 40B (second gap portion 43b), which is arranged so as to surround the first gap group 40A. It is fixed to the absorbent polymer particles 42 accommodated therein. Further, even if the highly viscous excretion liquid enters the second gap group 40B without being taken into the first gap group 40A, the highly viscous excretion liquid is fixed in the space in the second gap portion 43b. Will not spread to others.

  In addition, by appropriately setting the distribution of the gap groups 40A and 40B and the positional relationship between the leakage prevention grooves 9 described above, the fit of the napkin 1 to the wearer's body is improved, and leakage and discomfort at the time of wearing are reduced. It becomes possible. Specifically, although not shown, the leakage prevention groove 9 is formed in a region where the first gap group 40A where the average volume of the gap portion is relatively large exists, or in particular, the leakage prevention groove 9 is formed. The first gap group described above is formed at and near the boundary between the first gap group 40A having a relatively large average volume and the second gap group 40B having the relatively small average volume. While maintaining quick liquid uptake by the gap 43a constituting 40A, it is possible to suppress leakage due to penetration of liquid into the periphery of the first gap group 40A, and the leak-proof groove 9 has a flexible shaft. Thus, the napkin 1 can be bent into a desired shape.

  The gap 43 (43a, 43b) is a size that can accommodate the absorbent polymer particles 42 in a swollen state when one or more absorbent polymer particles 42 accommodated in the gap 43 absorb liquid and swell. Have As will be described later, the void 43 is formed by utilizing the swelling of the absorbent polymer particles 42 in the dry state due to liquid absorption and the reduction due to the drying of the absorbent polymer particles 42 in the swollen state. The length (volume) is substantially equal to the size when one or more absorbent polymer particles accommodated in the voids absorb liquid and swell.

  As described above, the absorbent body 4 includes the wet papermaking body 40, and a large number of voids 43 formed by utilizing the swelling of the absorbent polymer particles 42 and the subsequent reduction are formed in the wet papermaking body 40. As a result, the removal of the absorbent polymer particles 42 is effectively prevented, and even if the absorbent polymer particles 42 having a low degree of swelling are used, the strength of the absorbent body 4 (wet papermaking body 40) is not insufficient. As a result, sufficient practical strength is ensured. In general, absorbent polymer particles having a low degree of swelling have poor surface tackiness, and therefore, an absorber including such absorbent polymer particles tends to have a reduced strength.

  One or more absorbent polymer particles 42 are accommodated in constituent fibers (not shown) in at least some of the numerous voids 43. Here, the absorption polymer particles are supported on the constituent fibers means that the absorption polymer particles 42 enter the gap 43 and absorb even when external stress is applied to the wet papermaking body 40 (absorbent body 4). This refers to a state in which the polymer particles 42 are less likely to move or drop off extremely. At this time, the absorbent polymer particles 42 adhere to the constituent fibers due to their own stickiness, or the constituent fibers are entangled or caught on the absorbent polymer particles 42. In the first embodiment, the state in which the absorbent polymer particles 42 are supported is a binder separate from the fibers and the absorbent polymer particles 42 [for example, fused fibers (binder fibers), hot-melt pressure-sensitive adhesives, synthetic binders, etc. It is realized without using the above. Further, as described above, since the gap 43 is formed by utilizing the swelling of the absorbent polymer particles 42 and the subsequent reduction, the large number of the absorbent polymer particles 42 contained in the wet papermaking body 40 is large. The portions (preferably about 70% by weight or more, more preferably 80% by weight or more) of the large number of absorbent polymer particles 42 contained in the wet papermaking body 40 are individually present in the voids 43. The absorbent polymer particles 42 are supported on the fibers as described above in a state of being surrounded by the space in the gap 43. Here, “individual” includes a case where a plurality of absorbent polymer particles 42 exist in one void portion 43. Such a configuration makes it more difficult for the absorbent polymer particles 42 to fall off the absorbent body 4 (wet papermaking body 40), and the swelling of the absorbent polymer particles 42 due to liquid absorption is less likely to be inhibited. Improves liquid absorption.

  As a material for forming the absorbent polymer particles 42, various materials usually used in this type of absorbent article can be appropriately used. For example, poly (sodium acrylate), (acrylic acid-vinyl alcohol) copolymer, cross-linked poly (sodium acrylate), (starch-acrylic acid) graft polymer, (isobutylene-maleic anhydride) copolymer and saponified product thereof, Examples include potassium polyacrylate, cesium polyacrylate, and the like. One of these can be used alone, or two or more can be mixed and used.

  The particle shape of the absorbent polymer particle 42 is not particularly limited, and examples thereof include an indefinite shape, a lump shape, a bowl shape, a spherical shape, and a shape in which particles such as a spherical shape are aggregated. Further, the average particle diameter of the absorbent polymer particles 42 is not limited to the ability of the absorbent polymer particles 42 to drop off from the absorbent body 4 (wet papermaking body 40) and the absorption performance, and the thickness of the absorbent body 4 and the gap 43 From the viewpoint of size and the like, it is preferably 50 to 600 μm, particularly preferably 100 to 500 μm. The absorbent polymer particles 42 may be used in combination of two or more types having different average particle diameters. The average particle diameter of the absorbent polymer particles is measured as follows, for example.

<Measurement method of average particle diameter of absorbent polymer particles>
Absorbing polymer particles contained in the absorber are taken out, and 50 g of the absorbing polymer particles are added to a standard sieve having openings 850, 600, 500, 355, 300, 250, 150 defined in JIS Z 8801 (for example, Tokyo Screen Co., Ltd.). Using a shaker (for example, AS200 type, manufactured by Lecce), the product is sieved using a standard sieve) and a saucer. The shaking condition is 50 Hz, the amplitude is 0.5 mm, and the shaking time is 10 minutes. The weight of the tray under each sieve after shaking was measured, and the weight of the absorbent polymer particles on each sieve was calculated by subtracting the tare weight. The measurement was performed three times, and the average value was defined as the weight on the sieve. The obtained weight on each sieve was divided by 50, which is the total weight of the measured absorbent polymer particles, to determine the relative frequency, and a cumulative particle size curve was drawn. The particle diameter corresponding to the central cumulative value (50%) of the cumulative curve was taken as the average particle diameter. The measurement is performed at 23 ± 2 ° C. and humidity 50 ± 5%, and the sample is measured after being stored in the same environment for 24 hours or more.

  As the absorbent polymer particles 42, those having a low degree of swelling can be used. The disadvantages of using the absorbent polymer particles having a low degree of swelling, for example, the falling off of the absorbent polymer particles due to the decrease in the adhesiveness of the absorbent polymer particles themselves, the peel strength of the absorbent body, the decrease in the absorption performance, etc. This can be avoided by employing the wet papermaking body 40 having a large number of 43. As the absorbent polymer particles having a low degree of swelling, specifically, absorbent polymer particles having a centrifugal retention amount of 5 to 25 g / g, particularly 8 to 20 g / g are preferably used. The amount of centrifugal retention is measured as follows.

<Measuring method of centrifugal retention>
The measurement of the centrifugal holding amount was performed by cutting a nylon woven fabric (mesh opening 255, sold by Sanriki Seisakusho, product name: nylon net, standard: 250 × mesh width × 30 m) into a rectangle having a width of 11 cm and a length of 40 cm. Folded in the center in the direction and heat sealed at both ends to produce a nylon bag having a width of 11 cm (inner dimension: 10 cm) and a length of 20 cm. Weigh accurately 0.5 g of the absorbent polymer particles as the measurement sample, and place it uniformly in the bottom of the produced nylon bag. The nylon bag containing the sample is immersed in physiological saline (0.9% by weight sodium chloride water). One hour after the start of immersion, the nylon bag is taken out from the physiological saline, suspended in a vertical state for 30 minutes and drained, and then dehydrated using a centrifugal dehydrator (Kokusan Co., Ltd., model H-130C special model). The dehydration condition is 143 G (800 rpm) for 10 minutes. After dehydration, the weight of the sample is measured, and the target centrifugal retention amount is calculated according to the following formula. Centrifugal retention amount (g / g) = (a′−bc) / c; where a ′ is the total weight (g) of the sample and nylon bag after centrifugal dewatering, and b is before the nylon bag is absorbed (dried). C) represents the weight (g) of the sample before water absorption (during drying). The measurement was performed three times (n = 3), and the average value of the three points was taken as the measurement value. The measurement is performed at 23 ± 2 ° C. and humidity 50 ± 5%.

  The content of the absorbent polymer particles 42 in the wet papermaking body 40 is preferably 5 to 80% by weight, more preferably 10 to 70% by weight, based on the total weight of the wet papermaking body 40. In particular, when the napkin 1 is a thin napkin having a thickness (thickness under a load of 490 Pa) of 3 mm or less, the content of the absorbent polymer particles 42 is 10 to 70% by weight, particularly 30 to 60% by weight. However, it is preferable in terms of a balance between thinness and absorption performance.

  The wet papermaking body 40 contains pulp fibers as main fibers. The pulp fibers as the main fibers account for 50% by weight or more, preferably 80 to 100% by weight, of the constituent fibers of the wet papermaking body 40. Examples of the pulp fibers include wood pulps such as softwood kraft pulp (NBKP) and hardwood kraft pulp (LBKP), for example, “HBA” (trade name) manufactured by Warehauser, and bulky cellulose fibers such as mercerized pulp; Non-wood pulp such as cotton, cocoon and kenaf; regenerated cellulose fibers such as cupra and rayon, and the like can be used. One of these can be used alone, or two or more can be used in combination. From the viewpoint of cost, wood pulp is preferably used, and conifer kraft pulp and bulky cellulose fiber are particularly preferable.

  The pulp fibers preferably contain bulky cellulose fibers. By using bulky cellulose fibers as the main fibers of the wet papermaking body 40, the dispersibility and the degree of immobilization of the absorbent polymer particles 42 are further improved. Moreover, generation | occurrence | production of the gel blocking of the absorption polymer particle 42 can also be suppressed by using a bulky cellulose fiber. From this viewpoint, it is preferable that the ratio of the bulky cellulose fiber in the pulp fiber which is the main fiber in the wet papermaking body 40 is 10 to 90% by weight, particularly 30 to 80% by weight. The bulky fiber means that the fiber shape is a three-dimensional structure such as a twisted structure, a crimped structure, a bent and / or branched structure, or the fiber cross section is very thick (for example, the fiber roughness is 0.3 mg / m or more). ).

  The higher the proportion of the bulky cellulose fibers in the constituent fibers of the wet papermaking body 40 (the lower the proportion of NBKP used together), the higher the wet papermaking body 40 is and the higher the number of voids 43, and / or Or the volume of each gap portion 43 is large). On the other hand, the lower the proportion of bulky cellulose fibers in the constituent fibers of the wet papermaking body 40 (the higher the proportion of NBKP used together), the smaller the bulk of the wet papermaking body 40 and the lower the number of voids 43 (the number of voids 43). And / or the volume of each gap 43 is small). The high void wet papermaking body 40 has high liquid diffusibility and excellent flexibility, and the low void wet papermaking body 40 is particularly effective in reducing the thickness. Therefore, the desired wet papermaking body 40 can be obtained by adjusting the ratio of the bulky cellulose fiber and NBKP.

  Examples of preferred bulky cellulose fibers include cellulose fibers having a fiber roughness of 0.3 mg / m or more. Cellulose fibers having a fiber roughness of 0.3 mg / m or more accumulate in a bulky state, so that a bulky network structure capable of holding the absorbent polymer particles 42 is easily formed. Moreover, the movement resistance of the liquid is small, and the passage speed of the liquid is large. The fiber roughness is preferably 0.3-2 mg / m, particularly 0.32-1 mg / m.

  The fiber roughness is used as a scale representing the fiber thickness in fibers having non-uniform fiber thickness, such as wood pulp. For example, a fiber roughness meter (FS-200, KAJANNIELECTRONICSLTD. ).

Examples of cellulose fibers having a fiber roughness of 0.3 mg / m or more include softwood kraft pulp (“ALBACEL” (trade name) manufactured by Federal Paper Board Co. and PT Inti Indorayon Utama
“INDORAYON” (trade name)] and the like.

Other examples of preferred bulky cellulose fibers include cellulose fibers having a fiber cross-section roundness of 0.5 to 1, particularly preferably 0.55 to 1. Cellulose fibers having a roundness of the fiber cross section of 0.5 to 1 have a low liquid movement resistance and a high liquid permeation rate. The method for measuring roundness is as follows. The fiber is sliced perpendicular to the cross-sectional direction so that the area does not change, and a cross-sectional photograph is taken with an electron microscope. The cross-sectional photograph is analyzed by an image analysis apparatus [New Qubever. Using these values, the roundness is calculated using the following formula. The roundness is an average value obtained by measuring 100 arbitrary fiber cross sections.
Roundness = 4π (cross-sectional area of measurement fiber) / (peripheral length of cross-section of measurement fiber) ²

  As described above, it is preferable to use wood pulp as the pulp fiber, but in general, the cross section of the wood pulp is flattened by delignification treatment, and most of its roundness is less than 0.5. In order to make the roundness of such wood pulp 0.5 or more, for example, the wood pulp may be mercerized to swell the cross section of the wood pulp.

  Thus, as the bulky cellulose fiber, mercerized pulp having a roundness of 0.5 to 1 obtained by mercerizing wood pulp is also preferable. Examples of commercially available mercerized pulp that can be used in the present invention include “FILTRANIER” (trade name) manufactured by ITT Rayonier Inc., “POROSANIER” (trade name) manufactured by the same company, and the like.

  Moreover, when a cellulose fiber having a fiber roughness of 0.3 mg / m or more and a roundness of the fiber cross section of 0.5 to 1 is used, a bulky network structure is more easily formed, and the liquid passage speed is increased. Is also preferable because it becomes larger.

  The fiber length of the constituent fibers of the wet papermaking body 40 such as the pulp fibers is preferably 0.1 mm to 15 mm, more preferably 0.2 mm to 5 mm, from the viewpoint of absorption performance and ease of production.

  As constituent fibers of the wet papermaking body 40, non-pulp fibers can be used in addition to the pulp fibers (bulky cellulose fibers). Non-pulp fibers are preferably hydrophilic, for example, hydrophilic synthetic fibers such as polyvinyl alcohol fibers and polyacrylonitrile fibers; synthetic fibers such as polyethylene fibers, polypropylene fibers, and polyester fibers are hydrophilized with a surfactant. Thing; nylon fiber, cellulose diacetate fiber, cellulose triacetate fiber, etc. are mentioned, These 1 type can be used individually or in mixture of 2 or more types. The proportion of non-pulp fibers is preferably 50% by weight or less, particularly 1 to 20% by weight of the constituent fibers of the wet papermaking body 40.

  The fiber content in the wet papermaking body 40 is preferably 20 to 95% by weight, more preferably 30 to 90% by weight, based on the total weight of the wet papermaking body 40. In particular, when the napkin 1 is a thin napkin having a thickness (thickness under a load of 490 Pa) of 3 mm or less, the content of the fiber is 30 to 90% by weight, particularly 40 to 70% by weight. Is preferable in terms of the balance between absorption and absorption performance.

  In addition to the fibers and the absorbent polymer particles 42, the wet papermaking product 40 may further contain a wet paper strength enhancer such as polyamide / epichlorohydrin resin, dialdehyde starch, carboxymethylcellulose, polyvinyl alcohol, and the like; a dispersant and the like.

The basis weight of the wet papermaking body 40, absorption rate, absorption capacity, diffusion of the liquid, from the viewpoint of transparency, etc. of the liquid, preferably 15~250g / m ^2, more preferably at 50 to 120 / m ^2. When it is desired to further increase the absorption capacity, the wet papermaking body 40 can be used as a multilayer structure by stacking.

In addition, the thickness of the wet papermaking 40 under a load of 49 Pa (0.5 g / cm ² ) is preferably 0.3 from the viewpoint of thinness when the wet papermaking 40 is applied to a napkin and uncomfortable feeling when wearing the napkin. It is -2.7 mm, More preferably, it is 0.5-2.0 mm. The thickness is measured as follows.

<Method for measuring thickness>
Measure using a thickness meter (KES FB3-AUTO-A, manufactured by Kato Tech). The measurement object is placed on the measurement table so as not to be wrinkled or bent, and a pressure plate having a pressure area of 2 cm ² is pushed into the measurement object at a speed of 50 sec / mm to obtain a desired load (for example, When the object to be measured is the wet papermaking body 40, the thickness in a state where 49 Pa) is applied is measured. The measurement is performed at 22 ± 2 ° C. and humidity 65 ± 5%.

  Moreover, the bending rigidity of the wet papermaking body 40 is preferably 2 to 13 g, more preferably 2 to 9 g. The greater the bending stiffness of the wet papermaking body 40, the harder the wet papermaking body 40 bends. The fact that the bending stiffness of the wet papermaking body 40 is in such a range is largely due to the fact that a large number of voids 43 are formed therein, and the bending stiffness of the wet papermaking body 40 is in such a range, so that it is flexible. The effect that the papermaking body which is rich in property and is easy to deform | transform can be obtained. The bending stiffness is measured using a handometer (F360A DIGITAL INDICATOR, manufactured by Unipulse). A test piece of 40 mm × 40 mm wet papermaking body 40 is prepared, placed on a test bench with a slit interval set to 10 mm, and measured. The measurement was performed 5 times (n = 5), and an average value of 5 points was taken as a measured value. The measurement is performed at 23 ± 2 ° C. and humidity 50 ± 5%.

The napkin 1 can be thinned by including the absorber 4 having the above-described configuration. The thickness of the napkin 1 is preferably 0.5 to 5 mm, particularly 1 to 3 mm, because it does not feel uncomfortable while preventing leakage during wearing, and is convenient for carrying. The thickness of the napkin here means the thickness of the napkin under a load of 490 Pa (5 g / cm ² ), and is measured according to the above <Thickness measurement method>. The load 490 Pa (5 g / cm ² ) assumes a load applied by the wearer's weight while wearing the napkin.

  The napkin 1 of the first embodiment is used by being attached to an undergarment in the same manner as a normal sanitary napkin of this type. In the napkin 1 according to the first embodiment, the absorbent body 4 (wet papermaking body 40) has two void groups 40A and 40B having mutually different average volumes of the voids, and these void groups are appropriately arranged. Therefore, it is excellent in drawability and retention of liquid, and can exhibit excellent absorbency not only for low viscosity excretory liquid such as plasma and water, but also for high viscosity excretory liquid such as menstrual blood. it can. In addition, since the large number of absorbent polymer particles 42 in the absorbent body 4 are individually accommodated in the voids 43, the absorbent polymer particles 42 are unlikely to fall off, and the absorbent polymer particles 42 have a degree of swelling. Even if it is low, the strength of the absorber 4 is hardly lowered. Further, the napkin 1 of the present embodiment can be designed to have a small thickness because the absorbent body 4 has the above-described configuration, is not bulky, and is excellent in portability and wearing feeling.

  Hereinafter, other embodiments of the present invention will be described with reference to FIGS. Regarding other embodiments to be described later, components that are different from the napkin 1 of the first embodiment described above will be mainly described, and the same components will be denoted by the same reference numerals and description thereof will be omitted. The description about the napkin 1 of 1st Embodiment is applied suitably to the component which is not demonstrated especially.

  FIG. 5 shows a view corresponding to FIG. 4 (a schematic cross-sectional view along the width direction) of a modified example of the wet papermaking body 40 (absorbent body 4) in the napkin 1 of the first embodiment described above. In the wet papermaking body 40 in the first embodiment, the first gap group 40A is biased and arranged on the skin contact surface side of the central portion in the width direction (Y direction in the drawing) of the wet papermaking body 40. However, the first gap group 40A in the wet papermaking body 40a shown in FIG. 5 (a) is arranged over the entire region in the thickness direction of the central portion in the width direction of the wet papermaking body 40a. 40A is not unevenly distributed in the thickness direction of the wet papermaking body 40a (the vertical direction in FIG. 5). The thickness of the wet papermaking body 40a is the same as the thickness of the first gap group 40A and the thickness of the second gap group 40B.

  Moreover, in the wet papermaking body 40 in 1st Embodiment, although the 1st space | gap group 40A was embed | buried in the 2nd space | gap group 40B, the 1st in the wet papermaking body 40b shown in FIG.5 (b). The gap group 40A is arranged so as to protrude on the skin contact surface of the second gap group 40B. That is, the wet papermaking body 40b is configured by laminating the first gap group 40A narrower than the gap group 40B on the substantially flat skin contact surface of the second gap group 40B, The gap group 40A is arranged biased toward the skin contact surface side. While the non-skin contact surface of the wet papermaking body 40b is flat, the skin contact surface on the opposite side is an uneven surface due to the protruding gap group 40A.

  FIG. 6 shows a plan view of the skin contact surface side of still another modified example of the wet papermaking body 40 (absorbent body 4) in the napkin 1 of the first embodiment described above. In the wet papermaking body 40 in the first embodiment, the first gap group 40A is arranged only in the central part of the wet papermaking body 40 (the part corresponding to the excretory part facing part). The first gap group 40A in the wet papermaking body 40c shown in FIG. 4 is formed at the central portion in the width direction (Y direction in the figure) of the wet papermaking body 40c and the entire length in the longitudinal direction (X direction in the figure) of the wet papermaking body 40c. It is distributed over.

  In the wet papermaking body 40d shown in FIG. 6 (b), a plurality of first gap groups 40A are arranged apart from each other in the central portion in the width direction of the wet papermaking body 40d. In the wet papermaking body 40d, two first gap groups 40A having a rectangular shape in plan view are formed at the center in the width direction of the wet papermaking body 40d, and these two gap groups 40A and 40A are formed in the width direction. The other part of the wet papermaking body 40d, which is arranged at a predetermined interval and includes the gap between the two gap groups 40A and 40A, is the second gap group 40B.

  In the wet papermaking body 40e shown in FIG. 6 (c), the first gap group 40A is arranged over the entire length in the longitudinal direction of the wet papermaking body 40 on each of both sides in the width direction of the wet papermaking body 40e. The central portion in the width direction of the wet papermaking body 40e sandwiched between the both side portions is a second gap group 40B. The wet papermaking body 40e having such a configuration can relieve compression from the wearer's thigh when the napkin 1 is worn, can suppress twisting, has a stable absorption performance, and suppresses skin troubles due to rubbing. Can be expressed.

  In the wet papermaking body 40f shown in FIG. 6 (d), the first gap group 40A and the second gap group 40B are alternately arranged in the longitudinal direction of the wet papermaking body 40f. Each of the plurality of first gap groups 40A in the wet papermaking body 40f has a rectangular shape that crosses the wet papermaking body 40f in the width direction (Y direction in the drawing) in plan view. The wet paper-making body 40f having such a configuration can be deformed like a bow along the shape of the wearer's body when the napkin 1 is worn, and can improve the fit and suppress the leakage.

  In the wet papermaking bodies 40c to 40f shown in FIGS. 6 (a) to 6 (d), the first gap group 40A is i) buried in the second gap group 40B as shown in FIG. The wet papermaking body may be arranged in a biased manner on the skin contact surface side, or ii) as shown in FIG. 5 (a), the wet papermaking body is arranged over the entire region in the thickness direction of the predetermined portion. Alternatively, or iii) as shown in FIG. 5B, the second gap group 40B may be provided so as to protrude from the skin contact surface.

  The disposable diaper as 2nd Embodiment of the absorbent article of this invention is shown by FIGS. 7-11. The diaper 20 of the second embodiment includes a liquid-permeable top sheet 2 that forms a skin contact surface, a liquid-impermeable or liquid-permeable back sheet 3 that forms a non-skin contact surface, and both sheets 2. , 3 is provided with a liquid-retaining absorber 4 interposed between the two. As shown in FIG. 9, the absorbent body 4 (wet paper-making body 41) is substantially vertically long. The longitudinal direction of the absorbent body 4 coincides with the longitudinal direction of the diaper 20 (X direction in the figure), and the width direction of the diaper 20 ( It is arranged at the central portion in the Y direction in the figure. The absorbent body 4 is covered with a core wrap sheet (not shown), and an adhesive (hot melt) coated with patterns such as dots, spirals, and stripes is provided between the top sheet 2 and the back sheet 3 and the core wrap sheet. Are joined to each other by an adhesive or the like).

  As shown in FIG. 7, the diaper 20 is formed substantially vertically and has a ventral side A, a back side B, and a crotch C positioned between these A and B in the longitudinal direction. Yes. The abdominal side A is a part disposed on the wearer's abdomen when the diaper 20 is worn, the back side B is disposed on the back of the wearer, and the crotch C is disposed on the inseam of the wearer. It is a part. The ventral portion A, the dorsal portion B, and the crotch portion C substantially correspond to the respective regions when the diaper 20 is divided into three regions so that the entire length in the longitudinal direction is divided into three equal parts.

  The diaper 20 has an hourglass shape in which both side edges of the crotch portion C are curved in an arc shape and the central portion in the longitudinal direction is bound inward as a whole. The top sheet 2 and the back sheet 3 respectively extend outward from the left and right side edges and both front and rear ends of the absorbent body 4, and are joined to each other at the extended portions. The top sheet 2 is smaller in the width direction than the back sheet 3 in the width direction. The diaper 20 is a so-called unfolded disposable diaper, and a pair of fastening tapes FT are attached to left and right side edges along the longitudinal direction of the back side B, and the non-skin contact surface of the abdominal side A A landing tape LT for fastening the fastening tape FT is attached to the (non-skin contact surface of the back sheet 3).

  A sheet material 11 for forming a three-dimensional gather having the elastic member 10 is disposed on both the left and right sides along the longitudinal direction of the skin contact surface of the diaper 20 to form a three-dimensional gather. In addition, a pair of left and right elastic members 12 and 12 (two in the second embodiment) for forming leg gathers are disposed on both left and right side portions of the diaper 20 along the longitudinal direction. A gather is formed. The elastic members 12 for forming leg gathers are arranged in a substantially linear shape in an extended state in leg flaps extending outward in the width direction from the left and right side edges along the longitudinal direction of the absorber 4.

  One or more elastic members 10 (three in the first embodiment) are fixed to one side edge of the sheet material 11 for forming a three-dimensional gather in an expanded state. The sheet material 11 is joined to the surface sheet 2 along the longitudinal direction of the diaper 20 at positions outside the left and right side edges along the longitudinal direction of the absorbent body 4 along the longitudinal direction of the diaper 20. It is the rising base end 13 of the gather. The sheet material 11 extends outward in the width direction of the diaper 20 from the rising base end portion 13, and is joined to the back sheet 3 at the extended portion. The sheet material 11 is joined to the skin contact surface of the topsheet 2 at the front end portion 14 and the rear end portion 15 in the longitudinal direction of the diaper 20. The sheet material 11 for forming the three-dimensional gathers can be made of a material similar to a conventionally known material. For example, a liquid-impermeable or water-repellent porous resin film or a nonwoven fabric can be used.

  The absorbent body 4 includes a wet papermaking body 41 containing pulp fibers as main fibers, and is shown in FIG. 10 (cross-sectional view taken along line II in FIG. 9) and FIG. 11 (cross-sectional view taken along line II-II in FIG. 9). As shown in FIG. 2, a large number of absorbent polymer particles 42 are dispersedly arranged in the wet papermaking body 41. The basic structure of the wet papermaking body 41 is the same as the wet papermaking body 40 described above, and the difference between the two wet papermaking bodies 40 and 41 is the arrangement of the two gap groups 40A and 40B.

  In the wet papermaking body 41, as shown in FIG. 9, the first gap group 40A is biased to the back side B side. More specifically, the first gap group 40A is biased and arranged on the skin contact surface side of the region corresponding to the back side portion B (see FIG. 7) in the wet papermaking body 41. , But not at least on the ventral side A. The first gap group 40A may be continuous from the back side B to the crotch C. In the wet papermaking body 41, the first gap group 40A is buried in the second gap group 40B with its skin contact surface exposed, and forms the skin contact surface of the wet papermaking body 41. The skin contact surfaces of the gap group 40A and the gap group 40B are on the same plane, and the skin contact surface of the wet papermaking body 41 is flat.

  The diaper 20 of 2nd Embodiment can be used similarly to a normal expansion | deployment type diaper. According to the diaper 20 of the second embodiment, the same effect as that of the napkin 1 of the first embodiment can be obtained. However, excellent absorbency can be expressed. In particular, in the diaper 20 of the second embodiment, the first gap group 40A, which has a high fluid absorption rate and is excellent in the uptake of highly viscous excretory fluid such as loose stool, is biased toward the back side B side. Since it is arranged, it is possible to effectively prevent loose stool leakage.

  FIG. 12 is a diagram (perspective view) corresponding to FIG. 9 showing a modification of the wet papermaking body 41 (absorbent body 4) in the diaper 20 of the second embodiment described above. In the wet papermaking body 41 in the second embodiment, the first gap group 40A is buried in the second gap group 40B, but the first gap group 40A in the wet papermaking body 41a shown in FIG. The second gap group 40B is formed so as to protrude to the skin contact surface side. That is, the wet papermaking body 41a is configured by laminating the first gap group 40A having a length in the longitudinal direction X shorter than the gap group 40B on the substantially flat skin contact surface of the second gap group 40B. The gap group 40A is biased to the back side B in the longitudinal direction X, and biased to the skin contact surface side in the thickness direction of the wet papermaking body 41a. While the non-skin contact surface of the wet papermaking body 41a is flat, the skin contact surface on the opposite side is an uneven surface due to the protruding gap group 40A.

  Next, the manufacturing method of the absorber of this invention is demonstrated based on the preferable one embodiment. In the following, first, a method for producing a wet papermaking body having voids will be described, and then, in the production method, a method for forming a plurality of void groups having different void volume (method for controlling the volume of voids) will be described. The manufacturing method of the absorbent body 4 (wet papermaking body 40) in the above embodiment will be described as an example.

  The method for producing an absorbent body according to this embodiment includes a wet papermaking body containing pulp fibers as main fibers, and a method for producing an absorbent body in which a large number of absorbent polymer particles are dispersedly arranged inside the wet papermaking body. A process of wet papermaking an aqueous dispersion containing pulp fibers and absorbent polymer particles to form a wet fiber web, and drying the wet fiber web to swell the absorbent polymer particles in the wet fiber web And a step of reducing the size.

  The aqueous dispersion is prepared by dispersing or dissolving the components of the wet papermaking in water. The order of adding the aqueous dispersion to the preparation tank of each component is not particularly limited, but the addition of the absorbent polymer particles is performed immediately before the aqueous dispersion is subjected to wet papermaking, that is, the aqueous liquid is added to the wet paper machine network (wire). Immediately before flowing over (immediately before the wire part in the paper making process) is preferable. By adding the absorbent polymer particles to the preparation tank at such timing, the dispersibility of the absorbent polymer particles is enhanced, and the dispersion of the voids is promoted.

  The wet fiber web can be formed, for example, as follows. That is, after adding the non-pulp fiber to the mixture of the pulp fiber (bulky cellulose fiber) and water and stirring as necessary, an additive such as a wet paper strength enhancer is further added as necessary. Stir to obtain an absorbent polymer particle-free dispersion. The absorbent polymer particle-free dispersion is introduced into a wet paper machine, and immediately before paper making, the absorbent polymer particles are added to the absorbent polymer particle-free dispersion and stirred (that is, after the aqueous dispersion is prepared). The wet fiber web is formed by pouring it onto a net of a wet paper machine and flattening it in a conventional manner. This wet fiber web is constructed by dispersing and arranging absorbent polymer particles in a swollen state inside a wet fiber assembly. The swollen absorbent polymer particles are surrounded by wet fibers.

  The wet fiber web is then dried. The wet fiber web can be dried by using a dryer part of a paper making process in a normal wet paper making method. It is preferable to dehydrate the wet fiber web before drying the wet fiber web. The dehydration treatment can be performed using a press part of a paper making process in a normal wet paper making method. Specifically, first, in the press part, the wet fiber web is pressed with a felt (blanket) as necessary and compressed from above and below to squeeze out the moisture in the web, and then in the dryer part, a drying means is provided. Used to dry the wet fiber web that has been dehydrated. There is no restriction | limiting in particular in the said drying means, A Yankee dryer, an air through dryer, etc. can be used. In addition, as the wet paper machine, for example, a long paper machine, a twin wire paper machine, an on-top paper machine, a hybrid paper machine, or a round paper machine can be used.

  By drying the wet fiber web in this way, the absorbent polymer particles in a swollen state by absorbing the liquid in the web are also dried. At that time, the absorbent polymer particles in the swollen state are reduced in size as they are dried, and at the end of drying, the polymer particles almost return to the state before swelling (the dried state before adding to the preparation tank). The state of entanglement between the fibers and the shape of the fiber structure formed thereby do not substantially change before and after drying, and as a result, voids are formed around the reduced absorbent polymer particles. Many of the reduced absorbent polymer particles adhere to the fibers in the vicinity of the interface of the void due to their own tackiness, fiber entanglement or catching in the void. A wet papermaking body is thus obtained.

  The wet papermaking body 40 having two void groups 40A and 40B having different average volumes of the void portion 43 is obtained by controlling the volume of the void portion in the above-described wet papermaking method. As described above, the void portion of the wet papermaking according to the present invention is formed by utilizing the swelling of the absorbent polymer particles and the subsequent reduction, and the control of the volume of the void portion is performed by the wet papermaking body. This is done by adjusting the size (swelling volume) when the absorbent polymer particles are swelled during production. In the wet papermaking method described above, the wet papermaking 40 having two void groups 40A and 40B is obtained by developing two types of swollen absorbent polymer particles having different volumes. Examples of a method for developing a plurality of types of swollen absorbent polymer particles having different volumes in the production process of the wet papermaking body include the following methods 1) to 5). The methods 1) to 5) below can be combined as appropriate.

1) A plurality of types of absorbent polymer particles having different centrifugal retention amounts are used.
2) A plurality of types of absorbent polymer particles having different average particle diameters (average particle diameters in a dry state before swelling) are used.
3) A plurality of swelling liquids (solvents for the aqueous dispersion used in the above-mentioned wet papermaking method) for swelling the absorbent polymer particles are used.
4) A plurality of types of absorbent polymer particles having different liquid absorption rates are used.
5) In the above-mentioned wet papermaking method, the addition of the absorbent polymer particles to the solvent when preparing the aqueous dispersion is divided into a plurality of times.

  In the case of the above method 1), the absorbent polymer particles having a relatively large amount of centrifugal retention of the absorbent polymer particles are accommodated in the gap portion (first gap portion 43a) having a relatively large volume, and the centrifugal retention amount is relatively large. Absorbent polymer particles are accommodated in a void portion (second void portion 43b) having a relatively small volume.

  When the wet papermaking body 40 is produced by the above method 1), for example, the absorbent polymer particles having a centrifugal retention amount in the range of 5 to 12 g / g and the absorbent polymer having a centrifugal retention amount in the range of 15 to 25 g / g. Particles can be used. The amount of centrifugal retention is measured as described above.

  In the case of the above method 2), if the centrifugal retention amounts of the plurality of types of absorbent polymer particles are substantially the same, the absorbent polymer particles having a relatively large average particle diameter have a void volume (first The absorbent polymer particles having a relatively small average particle diameter are accommodated in the void portion (second void portion 43b) having a relatively small volume. When the wet papermaking body 40 is produced by the method 2), for example, absorbent polymer particles having an average particle diameter in the range of 350 to 700 μm and absorbent polymer particles having an average particle diameter in the range of 20 to 300 μm are used. be able to.

  The method 3) uses a plurality of kinds of swelling liquids having different compositions instead of using one kind of absorbent polymer particles, and utilizes the fact that the swelling volume of the absorbent polymer particles is affected by the liquid to be absorbed. Is. When the wet papermaking body 40 is manufactured by the above method 3), two types of the aqueous dispersions corresponding to the two gap groups 40A and 40B are prepared, and each aqueous dispersion is used alone, according to a conventional method. Two types of wet papermaking bodies (a wet papermaking body corresponding to the gap group 40A and a wet papermaking body corresponding to the gap group 40B) were obtained, and the two types of wet papermaking bodies thus obtained were stacked in a wet state and dried. The wet papermaking body 40 is obtained by integrating them by a known joining means such as an adhesive or heat seal after drying them individually or by drying them individually. Examples of the swelling liquid include water, aqueous solutions of various alkali metal or alkaline earth metal salts, such as aqueous solutions of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, and various alcohols such as polyethylene glycol, polypropylene glycol, 1 , 3-butanediol, glycerin, dipropylene glycol, ethanol and the like can be used. A particularly preferred combination of swelling liquids is an aqueous solution of water and various alkali metal or alkaline earth metal salts.

  The method 4) utilizes the fact that the liquid absorption rate and the swelling volume of the absorbent polymer particles are in a proportional relationship, particularly in the initial stage of liquid absorption by the absorbent polymer particles. In the case of the method 4), the absorption polymer particles having a relatively high liquid absorption rate are accommodated in the void portion (first void portion 43a) having a relatively large volume, and the absorption rate is relatively low. The polymer particles are accommodated in a void portion (second void portion 43b) having a relatively small volume. In the case of producing the wet papermaking body 40 by the method 4), from the viewpoint of reliably forming the two void groups 40A and 40B having different average volumes, the absorbency is increased before the swelling ratio of the absorbent polymer particles is maximized. The wet fiber web is preferably formed from an aqueous dispersion containing polymer particles according to a conventional method.

  The liquid absorption rate of the above-described absorbent polymer particles can be, for example, the water absorption rate by the vortex method as an index. When the wet papermaking body 40 is produced by the method 4), for example, the absorption polymer particles having a water absorption rate by the vortex method in the range of 10 to 30 seconds and the water absorption rate by the vortex method are in the range of 40 to 120 seconds. Absorbing polymer particles can be used. The water absorption rate by the vortex method is measured as follows.

<Measurement method of water absorption rate by vortex method>
A 100 mL glass beaker, 50 mL of physiological saline (0.9% by mass sodium chloride water) and a magnetic stirrer chip (center diameter 8 mm, both ends diameter 7 mm, length 30 mm, surface coated with fluororesin ) And place the beaker on a magnetic stirrer (HPS-100 manufactured by ASONE). The rotational speed of the magnetic stirrer is adjusted to 600 ± 60 rpm, and the physiological saline is stirred. 2.0 g of the water-absorbing polymer as a measurement sample is put into the liquid at the center of the vortex of the saline solution being stirred, and the water absorption rate (seconds) of the water-absorbing polymer is measured in accordance with JIS K 7224 (1996). taking measurement. Specifically, the stopwatch is started when the absorption of the water-absorbing polymer into the beaker is completed, and stopped when the stirrer tip is covered with the test liquid (when the vortex disappears and the liquid surface becomes flat). Stop the watch and record the time (in seconds) as the water absorption rate by vortex method. In the measurement, n = 5 was measured, the values at each of the upper and lower points were deleted, and the average value of the remaining three points was taken as the measured value. These measurements are performed at 23 ± 2 ° C. and a humidity of 50 ± 5%, and the samples are stored for 24 hours or more in the same environment before the measurement.

  In the method 5), instead of using one kind of absorbent polymer particles and one kind of swelling liquid, the addition of the absorbent polymer particles to the solvent when preparing the aqueous dispersion is divided into a plurality of times. That is, in the above-mentioned wet papermaking production method, when the absorbent polymer particle-free dispersion is introduced into a wet paper machine and the absorbent polymer particles are added to the absorbent polymer particle-free dispersion immediately before papermaking, Add the ingredients in several batches. In this method, the absorbent polymer particles added first have the largest swelling volume, and the swelling volume becomes smaller as the addition is delayed. When the wet papermaking body 40 is produced by the method 5), for example, the absorbent polymer particles may be added in two portions. In this case, the first added absorbent polymer particles are voids having a relatively large volume. The absorbent polymer particles that are accommodated in the portion (first void portion 43a) and then added are accommodated in the void portion (second void portion 43b) having a relatively small volume. Thus, when the absorbent polymer particles are added multiple times, the time from the addition of the absorbent polymer particles to the next addition depends on the type of the absorbent polymer particles, the production rate of the wet papermaking, the wet papermaking. It is set as appropriate in consideration of the design of absorption characteristics of the body.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, the absorbent article to which the absorbent body of the present invention can be applied, or the absorbent article of the present invention is not limited to sanitary napkins or unfolded disposable diapers, but pants-type disposable diapers, incontinence pads, urine collecting pads It can also be applied to pet diapers and pet sheets.

  Further, the absorbent body of the present invention is not limited to those generally responsible for the absorption of excrement in absorbent articles such as diapers and napkins, and is used for the purpose of absorbing a certain liquid regardless of the amount of absorption. It is also applicable to what is done. For example, a) used for the purpose of absorbing the sweat of the wearer by arranging it around the waist of the diaper, or b) mixed-fiber absorbent (fiber and absorbent polymer particles mixed in the air) In absorbent articles comprising a main absorbent body as a main absorbent body, the main absorbent body can be supplemented by assisting the main absorbent body by being disposed on the skin contact surface side, side edge, or gathered portion of the main absorbent body. It can also be used for things that have a good absorbency.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

  Two types of absorbent polymer particles A and B were produced by the following <Method for synthesizing absorbent polymer particles>. Absorbent polymer particle A and absorbent polymer particle B differ only in the amount of crosslinking agent used in the surface crosslinking treatment. In the synthesis of absorbent polymer particle A, 1 g of the crosslinking agent is used, and in the synthesis of absorbent polymer particle B, the crosslinking agent is 15 g. Using. The centrifugal retention amount of the absorbent polymer particles A was 18 g / g, and the centrifugal retention amount of the absorbent polymer particles B was 10 g / g.

<Method of synthesizing absorbent polymer particles>
Polyoxyalkylene ether phosphate 0.1% [as opposed to acrylic acid weight] 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, thermometer As an active ingredient], 1500 ml of normal heptane was added. The temperature was raised to 90 ° C. while stirring in an atmosphere of nitrogen gas, and a separately prepared sodium acrylate aqueous solution was added to the reaction vessel in the presence of 2,2′-azobis (2-amidinopropane) dihydrochloride as a polymerization initiator. The polymerization was conducted dropwise. Thereafter, an aqueous ethylene glycol diglycidyl ether solution was added as a crosslinking agent. After cooling, the absorbent polymer particles were obtained by removing and drying normal heptane and water. The absorbent polymer particles thus obtained were charged into the 5 L reaction vessel (using an anchor blade), sucrose fatty acid ester was charged as a dispersant, and the temperature was raised to 75 ° C. with stirring in normal heptane in a nitrogen atmosphere. Thereafter, the cross-linking agent and an aqueous ethylene glycol diglycidyl ether solution are added, the surface of the absorbent polymer particles is subjected to surface cross-linking treatment, and after cooling, the normal heptane and water are removed and dried to achieve the target surface cross-linking treatment. Absorbing polymer particles were obtained.

[Example 1]
After 100 parts by weight of pulp fiber, 2 parts by weight of polyvinyl alcohol fiber, and 16000 parts by weight of water are dispersed and mixed in a mixer, a wet paper strength reinforcing agent is further added to 100 parts by weight of the dry weight of the pulp fiber. On the other hand, the resin component was added to the mixer so as to be 0.44 parts by weight, and dispersed and mixed to obtain an aqueous dispersion. In addition, as the pulp fiber, a bulky cellulose fiber “HBA” (trade name) manufactured by Warehauser and NBKP are used in a weight ratio of HBA: NBKP = 8: 2, and the polyvinyl alcohol fiber is as follows: A fiber “Fibribond” (trade name) manufactured by Sansho Co., Ltd. was used, and Kaimen GX-3 (manufactured by Riken Green Co., Ltd.) was used as the wet paper strength enhancer. The aqueous dispersion was transferred to a wet paper machine filled with water, and immediately before the wet paper making, the absorbent polymer particles A (centrifugal holding amount 18 g / g) were added to the aqueous dispersion and stirred. A wet fiber web was formed by wet papermaking. Next, a filter paper is pressed on the wet fiber web to dehydrate it, and the water in the web is appropriately removed. Then, the web is dried using a Yankee dryer and the dryer surface temperature is set to 130 ° C., and the basis weight is 240 g. / M ² of wet papermaking A (absorber) was obtained.

Further, a wet papermaking B (absorber) having a basis weight of 240 g / m ² was obtained in the same manner as described above except that the absorbent polymer particle B (centrifugal holding amount 10 g / g) was used instead of the absorbent polymer particle A. Obtained. The content of the absorbing polymer particles in the wet papermaking bodies A and B was 37.5% by weight with respect to the total weight of the wet papermaking body.

  The wet papermaking A was cut into a length of 90 mm and a width of 45 mm, and the wet papermaking B was cut into a length of 220 mm and a width of 80 mm. And the same as the cut wet papermaking A in the width direction central part of the region located closer to the other end in the longitudinal direction than the position spaced 50 mm inward in the longitudinal direction from one longitudinal end of the cut wet papermaking B A recess having a size was provided, and the wet papermaking product A was fitted into the recess to obtain an absorbent body composed of a composite of the wet papermaking product A and the wet papermaking product B. The absorbent body thus obtained has a structure generally shown in FIG. 3 and FIG. 4 (corresponding to the form i)), the absorbent body thickness T1 is 4 mm, and wet papermaking A (first void group). The thickness T2 was 2 mm. The whole obtained absorbent body was covered with a core wrap sheet, and combined with a surface sheet, a back sheet and the like collected from a commercially available sanitary napkin (trade name “Laurier Skin Clean Absorption”, manufactured by Kao Corporation). 1 sanitary napkin was obtained. The sanitary napkin of Example 1 has a structure generally shown in FIGS. Further, when the average volume of the voids of the absorber was measured according to the method described above, the average volume (V1) of the voids in the region of the wet papermaking A having relatively large voids and the wet papermaking having relatively small voids. The ratio (V1 / V2) to the average volume (V2) of the voids in the region of the body B was 1.8.

[Example 2]
Using the wet papermaking products A and B prepared in Example 1, the following absorbers were prepared. Two pieces of wet papermaking A cut into 220 mm in length and 15 mm in width were prepared, and wet papermaking B was cut into 220 mm in length and 50 mm in width. Then, the two wet papermaking bodies A are arranged without gaps so that the wet papermaking body B is sandwiched from the width direction, and a collection body having a total width of 80 mm made of a composite of the wet papermaking body A and the wet papermaking body B is obtained. It was. The absorbent body thus obtained has a structure generally shown in FIG. 6C and the form of ii), and the wet papermaking body A is not unevenly distributed in the thickness direction of the absorbent body (composite). The entire obtained absorbent body was covered with a core wrap sheet, and a sanitary napkin of Example 2 was obtained in combination with the same top sheet, back sheet and the like as Example 1.

Example 3
After 100 parts by weight of pulp fibers and 16000 parts by weight of water were put into a mixer and dispersed and mixed, a wet paper strength reinforcing agent was further added in an amount of 0.44 parts by weight as a resin component with respect to 100 parts by weight of the dry weight of the pulp fibers. The mixture was put into the mixer so as to be dispersed and mixed to obtain an aqueous dispersion. In addition, NBKP was used as the pulp fiber, and sponge GX-3 (manufactured by Riken Green) was used as the wet paper strength enhancer. The aqueous dispersion was transferred to a wet paper machine filled with water, and immediately before the wet paper making, the absorbent polymer particles A (centrifugal holding amount was 18 g / g) were added to the aqueous dispersion and stirred. A wet fiber web was formed according to the wet papermaking method. Next, a filter paper is pressed on the wet fiber web to dehydrate it, and the water in the web is appropriately removed. Then, the surface of the dryer is dried at 130 ° C. using a Yankee dryer, and the basis weight is 250 g. / M ² of wet papermaking C (absorber) was obtained.

Further, a wet papermaking D (absorber) having a basis weight of 150 g / m ² was obtained in the same manner as described above except that the absorbent polymer particle B (centrifugal holding amount 10 g / g) was used instead of the absorbent polymer particle A. Obtained. The content of the absorbing polymer particles in the wet papermaking bodies C and D was 39.5% by weight with respect to the total weight of the wet papermaking body.

  The wet papermaking body C was cut into a length of 150 mm and a width of 90 mm, and the wet papermaking body D was cut into a length of 300 mm and a width of 90 mm. And the wet papermaking body C and the wet papermaking body D are laminated | stacked on the skin contact surface of the wet papermaking body D so that both papermaking bodies C and D may mutually correspond in the longitudinal direction rear end. An absorber composed of the composite was obtained. The absorbent body thus obtained generally has the structure shown in FIG. Cover the entire absorbent body with a core wrap sheet, and combine it with a commercially available baby diaper (trade name "Merry's Sarasara Air-Through Newborn Size", manufactured by Kao Corporation), a top sheet, a back sheet, an elastic member, etc. Thus, the disposable diaper of Example 3 was obtained. A position of 30 mm closer to the center in the longitudinal direction than the front end portion of the topsheet was taken as the position of the absorber front end portion. The disposable diaper of Example 3 has a structure generally shown in FIGS.

[Comparative Example 1]
A pulp sheet (NBKP manufactured by Warehauser) is loosened through a sieve having an opening of 1 mm, and the pulp fibers passing through the sieve and the absorbent polymer particles A are alternately piled to obtain a mixed pile, The fibrous body was pressed to obtain a so-called mixed fiber absorbent having a basis weight of 240 g / m ² , and a sanitary napkin was prepared in the same manner as in Example 1 to obtain a sample of Comparative Example 1. . Content of the absorption polymer particle in the absorber of the comparative example 1 was 37.5 weight% with respect to the total weight of this absorber. The absorbent body of Comparative Example 1 is an absorbent body that does not have the above-described “void portion surrounded by constituent fibers of a wet papermaking body and containing one or more absorbent polymer particles”.

[Comparative Example 2]
The absorbent polymer particles A are dispersed on one surface of a lower layer mount (wet paper made of blended pulp containing NBKP and LBKP at a ratio of NBKP: LBKP = 9: 1) having a basis weight of 20 g / m ^2. after the amount is uniformly sprayed so as to 30g / m ^2, NBKP over the absorbent polymer particles a, at a basis weight 30 g / m ² of the upper mount (NBKP and LBKP and the weight ratio: LBKP = 9: 1 A laminated pulp wet blend), and a laminate is obtained, and the laminate is pressed to obtain a so-called sandwich-type absorber having a basis weight of 80 g / m ^2. A sanitary napkin was prepared in the same manner as in Example 1 and used as the sample of Comparative Example 2. Content of the absorption polymer particle in the absorber of the comparative example 2 was 37.5 weight% with respect to the total weight of this absorber. The absorbent body of Comparative Example 2 is an absorbent body that does not have the above-described “void space surrounded by constituent fibers of a wet papermaking body and containing one or more absorbent polymer particles”.

[Comparative Example 3]
The whole wet papermaking B produced in Example 1 was covered with a core wrap sheet, and a sanitary napkin of Comparative Example 3 was obtained in combination with the same topsheet, backsheet and the like as Example 1.

[Comparative Example 4]
Softwood pulp (manufactured by Wafer User, NB-416) is opened with a garnet cylinder, and 300 parts by weight of the resulting defibrated pulp (fluff pulp) and 200 parts by weight of commercially available absorbent polymer particles (Sunwet IM930 made by Sundia polymer) , A centrifugal holding amount of 32 g / g) was mixed in an air stream, and stacked while sucking from the inner surface of the mesh. The total basis weight of the mixed product of pulp and absorbent polymer particles was 400 g / m ² . The obtained piled body is wrapped with a tissue paper having a basis weight of 16 g / m ² and spray-coated with a hot melt adhesive to obtain an absorbent body. Using this, a disposable diaper for a baby is produced in the same manner as in Example 3. Thus, a sample of Comparative Example 4 was obtained. Content of the absorption polymer particle in the absorber of the comparative example 4 was 39.5 weight% with respect to the total weight of this absorber. The absorbent body of Comparative Example 4 is an absorbent body that does not have the above-described “void space surrounded by constituent fibers of a wet papermaking body and containing one or more absorbent polymer particles”.

[Evaluation]
About the sample of an Example and a comparative example, it measured by the following method about the following item, respectively. For the samples of Examples 1 and 2 and Comparative Examples 1 to 3 (sanitary napkins), blood absorption time, liquid return amount, and liquid remaining amount were measured. About the sample (disposable diaper) of Example 3 and Comparative Example 3, the permeability | transmittance of the pseudo-soft stool (viscous material) was measured. Moreover, the absorber (wet papermaking body) in the samples of Examples 1 to 3 and Comparative Example 3, that is, “a void portion surrounded by constituent fibers of the wet papermaking body and containing one or more absorbent polymer particles” It was evaluated whether or not a plurality of void groups having different average volumes of the void portions were formed according to the method described above. The results are shown in Table 1 below.

<Measurement method of blood absorption time>
With the sanitary napkin to be measured spread in a plane and fixed on a horizontal surface with the top sheet facing up, an acrylic plate with a cylindrical injection part is placed on the top sheet in the center of the absorber. Further, a weight is placed on the acrylic plate, and a load of 5 g / m ² is applied to the center of the absorber. The injection part provided on the acrylic plate has a cylindrical shape with an inner diameter of 10 mm, and the central axis of the cylindrical injection part coincides with the central axis in the longitudinal direction and the width direction of the acrylic plate, and the cylindrical injection part A through-hole having an inner diameter of 10 mm is formed so as to communicate between the inside and the surface sheet facing surface of the acrylic plate. Next, the acrylic plate is arranged so that the central axis of the cylindrical injection portion coincides with the central portion of the absorber in plan view, and 3 g of blood is injected from the cylindrical injection portion and absorbed by the sanitary napkin. The time (seconds) from when the blood (defibrinated horse blood, manufactured by Nihon Biotest Co., Ltd.) reaches the surface of the napkin until the total amount of 3 g is absorbed by the napkin is measured, and this is the first blood absorption. It was time. In addition, 3 minutes after the first blood injection, the above procedure is repeated until 3 g of blood is further injected (a total of 6 g of blood is injected) until the total amount of the reinjected blood is absorbed by the napkin. Time (seconds) was measured, and this was taken as the second blood absorption time. The smaller the value of these blood absorption times, the faster the absorption rate and the higher the evaluation. Table 1 below shows the blood absorption time for the second time (when 6 g of blood was injected). In addition, in the first time, when it exceeded 3 minutes until the total amount (3 g) of the injected blood was absorbed, the next 3 g was injected immediately after the total amount was absorbed.

<Measurement method of liquid return amount>
In the above <Measurement method of blood absorption time>, 3 minutes after the third blood injection, the acrylic plate and the weight are removed, and the basis weight of 30 g is 7 cm × 15 cm on the skin contact surface of the napkin (on the top sheet). 10 sheets of / m ² absorbent paper (commercial tissue paper) were placed on top of each other, and a load of 68 g / cm ² was applied for 1 minute from the top of the absorbent paper. After the loading, 10 sheets of absorbent paper were removed, and the weight of the 10 sheets of absorbent paper was measured. From this measured value and the measured value of the weight of 10 sheets of absorbent paper before the load obtained in advance, the weight (g) of blood absorbed in 10 sheets of absorbent paper is determined, and this weight is taken as the liquid return amount. did. The smaller the liquid return amount, the higher the napkin absorption performance and the higher the evaluation.

<Measurement method of remaining liquid amount>
Place a sanitary napkin horizontally, put an acrylic plate with a 1 cm diameter injection port on top, and inject 3 g of defibrinated horse blood (manufactured by Nippon Biotest Co., Ltd.) for 1 minute. That state was maintained. Next, the acrylic plate is removed, the surface sheet is taken out from the napkin, and its weight is measured. The weight of the surface sheet before blood injection, which is measured in advance, is subtracted from the weight, and the difference (defibrillation remaining in the surface sheet is removed). The weight of the horse blood) was taken as the remaining liquid amount. The smaller the remaining amount of liquid, the better the dry feeling and the higher the evaluation.

<Permeability of simulated soft stool (viscous material)>
As shown in FIG. 13, an evaluation object (disposable diaper) P is sandwiched between an upper cylinder 91 having an inner diameter of 35 mm and a lower cylinder 92 having an inner diameter of 35 mm, and provided at the lower end of the upper cylinder 91 and the upper end of the lower cylinder 92. The clip 93 was fitted to the annular flange portion, and the upper and lower cylinders 91 and 92 were connected. Reference numerals 94 and 94 denote packings having through-holes having the same diameter and the same shape as the inner diameters of the cylinders 91 and 92. Then, 10 g of a viscous liquid (viscosity: 290 mPa · s) obtained by mixing glycerin and ion-exchanged water at a ratio of glycerin: ion-exchanged water = 94: 6 is poured into the upper cylinder 91 as pseudo-soft stool ( The entire amount was injected within 6 seconds), and the time from the start of injection until the liquid on the evaluation object P disappeared was measured. The measured value is shown in the following Table 1 as the liquid passing time.

  Each of the absorbent articles of Examples 1 to 3 has an absorbent body (wet papermaking) having a "void surrounded by the constituent fibers of the wet papermaking body and containing one or more absorbent polymer particles". As shown in Table 1, a plurality of (two) void groups having different average volumes of the void portions described above were formed inside the absorber. As is clear from the results shown in Table 1, the sanitary napkins of Examples 1 and 2 having such a configuration have a shorter blood absorption time and a liquid return amount than the sanitary napkins of Comparative Examples 1 to 3. And the remaining amount of liquid is small. From this, it can be seen that the sanitary napkins of Examples 1 and 2 are excellent in the drawability and retention of the liquid and exhibit excellent absorbency even for highly viscous liquids. Moreover, it turns out that the disposable diaper of Example 3 is shorter than the disposable diaper of the comparative example 4, and the liquid passing time of a pseudo soft stool is short, and it is excellent in the passage property of a viscous thing. Furthermore, the absorbers in the absorbent articles of Examples 1 to 3 were all thin, had sufficient absorption performance, and maintained flexibility. In contrast, in the absorbent articles of Comparative Examples 1, 2, and 4, all of the absorbents were "a void portion surrounded by constituent fibers of the wet papermaking body and containing one or more absorbent polymer particles. It can be seen that there is room for improvement particularly in terms of absorbability for highly viscous liquids. Moreover, although the absorbent article of Comparative Example 3 has the void portion, a plurality of void groups having different average volumes of the void portions are not formed inside the absorbent body. In particular, it can be seen that there is room for improvement in terms of the remaining amount of liquid.

1 Sanitary napkin (absorbent article)
2 Top sheet 3 Back sheet 4 Absorber 20 Disposable diaper (absorbent article)
40, 40a, 40b, 40c, 40d, 40e, 40f, 41, 41a Wet paper-made body 42 Absorbing polymer particles 43 Void portion 43a First void portion 43b Second void portion 40A First void group 40B Second void group

Claims (5)

An absorbent body comprising a wet papermaking containing pulp fibers as the main fiber, wherein a large number of absorbent polymer particles are dispersed inside the wet papermaking,
Inside the wet papermaking body, a plurality of voids are formed that are surrounded by constituent fibers of the wet papermaking and contain one or more absorbent polymer particles. The groups differ from each other in the mean volume of the voids ,
A first void group having a relatively large average volume of the voids and a second void group having a relatively small average volume, and an average of the first void group; The absorber whose ratio (V1 / V2) of the volume V1 and the average volume V2 of the group of the second void portion is 1.5 to 100 .   The void portion has a size that can accommodate the absorbent polymer particles in a swollen state when one or more of the absorbent polymer particles accommodated in the void portion absorbs liquid and swells. The absorber according to claim 1. Absorber according to claim 1 or 2, wherein the mean volume V1 of the group of the first air-gap portion is 0.01 to 0.2 mm ^3. An absorbent article comprising a top sheet that forms a skin contact surface, a back sheet that forms a non-skin contact surface, and a substantially vertically long absorbent disposed between both sheets,
The said absorber is an absorber as described in any one of Claims 1-3, And the average volume of the said space | gap part is relatively large, and this average volume is relative. And a second group of small voids,
The group of said 1st space | gap parts is an absorbent article distribute | arranged to the skin contact surface side of the width direction center part of the said absorber. It has a top sheet that forms a skin contact surface, a back sheet that forms a non-skin contact surface, and a substantially vertically long absorber disposed between both sheets. An absorbent article having in the longitudinal direction a ventral side portion and a back side portion arranged on the back side,
The said absorber is an absorber as described in any one of Claims 1-3, And the average volume of the said space | gap part is relatively large, and this average volume is relative. And a second group of small voids,
The group of said 1st space | gap parts is an absorptive article arranged biased to the said back side part side.

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