JP2010136969A - Absorbent body, method of manufacturing the same, and absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soft absorbent body with features of a thin type, practically sufficient liquid absorbability and strength and difficult falling-off of absorbent polymer particles, and to provide the method of manufacturing the absorbent body and absorbent article manufactured from this absorbent body. <P>SOLUTION: The absorbent body 4 includes a wet material 40 containing mainly pulp fibers, in which many absorbent polymer particles 42 are scattered or arranged. Within the wet material 40, there are lots of apertures 43 each surrounded by component fibers 41 and containing one or more absorbent polymers 42. Each aperture 43 is large enough to accommodate the one or more absorbent polymer particles 42 even when the polymer particles 42 accommodated in the apertuer 43 are swollen after absorbing liquid. The wet material 40 contains pulp fibers and many absorbent polymers 42, and is manufactured by drying a web of these absorbent polymers 42 in a wet and swollen state by absorbing liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  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. . For example, Patent Document 1 describes an absorbent body in which an adhesive is applied between two upper and lower absorbent materials, and absorbent polymer particles are fixed between the absorbent materials. Patent Document 2 discloses an absorptivity in which absorbent polymer particles are dispersedly arranged inside an absorbent sheet including fibers and the absorbent polymer particles are bonded and fixed to constituent fibers of the absorbent sheet. A sheet is described. The absorbent sheet described in Patent Document 2 is obtained by dispersing absorbent polymer particles on a wet fiber web made by a wet papermaking method, and superposing separately prepared fiber aggregates on the absorbent polymer particles. Obtained by drying and integration. Further, in Patent Document 3, the absorbent polymer particles are dispersed and arranged in the thickness direction of the absorbent sheet, and the average particle diameter of the absorbent polymer particles is decreased from one side of the absorbent sheet toward the other side. An absorbent sheet is described. Such an absorber is required to have practically sufficient liquid absorptivity and strength, and to prevent the absorbent polymer particles from dropping off.

  By the way, for some people represented by the Malay people whose main residence area is Indonesia, Malaysia, etc., it is customary to wash used sanitary napkins with water and wash away absorbed menstrual blood There is. Traditionally, sanitary napkins mainly used in Malay ethnic spheres are made of cloth-made napkins and water-absorbing materials that contain pulp fibers and do not contain absorbent polymers. The absorbed menstrual blood and the like can be washed away with water. On the other hand, sanitary napkins containing absorption polymers as described in Patent Documents 1 to 3 adhere firmly to the absorption polymer with colored components such as hemoglobin in menstrual blood. It was difficult to wash away blood, and washing with water was difficult.

  However, sanitary napkins that do not contain an absorbent polymer have poor menstrual blood absorption / retention performance, and may cause so-called liquid return, for example, where body fluid absorbed on the surface of the absorbent material oozes out. Therefore, in a conventional sanitary napkin that can be washed with water and does not contain an absorbent polymer, a shortage of absorbent performance is compensated by using a large amount of pulp fiber. However, such sanitary napkins become thick due to the bulkiness of the pulp fibers, are particularly bulky when folded and packaged, are inconvenient to carry, and have a poor fit.

  At present, the present applicant has not found any prior art documents that have raised the above-mentioned problems relating to water washing of napkins. However, people who have a habit of cleaning napkins are thought to exist in areas other than the above-mentioned residential areas, and sanitary napkins that contain absorbent polymers and can be washed thinly with water are widely used in women's lifestyles. It is thought that it has the potential to make a big impact.

Japanese Patent No. 5-38350 JP-A-8-246395 JP 2007-167193 A

  Accordingly, an object of the present invention is to provide a flexible absorbent body, a method for producing the absorbent body, and the absorbent body, which are thin, have practically sufficient liquid absorbency and strength, and hardly cause the absorbent polymer particles to fall off. It is to provide an absorbent article. Furthermore, it is providing the absorber which can be washed with water, the manufacturing method of an absorber, and the absorbent article using this absorber.

  As a result of various studies to solve the above-mentioned problems, the present inventors have used menstrual blood that has been absorbed by using particles having a low degree of swelling when absorbing liquid as absorbent polymer particles contained in the absorbent body. It has been found that the redness of the absorber due to the blood of can be greatly reduced by washing the absorber with water. Further, when such absorbent polymer particles having a low degree of swelling are used, the adhesiveness of the absorbent polymer particles themselves is lowered, which may cause the absorbent polymer particles to fall off or the absorber peel strength to decrease. Such an inconvenience is formed by making the absorbent body from a wet papermaking body, and utilizing the swelling of the absorbent polymer particles in the dry state due to liquid absorption and the reduction by drying of the absorbent polymer particles in the swollen state inside the wet papermaking body. It was found that this can be avoided by forming a large number of voids. Furthermore, it has been found that the absorption performance and flexibility of the absorber are improved by forming a large number of such voids in the absorber.

  The present invention has been made on the basis of the above knowledge, and is configured to include a wet papermaking containing pulp fiber as a main fiber, and an absorbent body in which a large number of absorbent polymer particles are dispersedly arranged inside the wet papermaking. In the wet papermaking body, a large number of voids surrounded by constituent fibers of the wet papermaking and containing one or more absorbent polymer particles are formed, and the voids are To provide an absorbent body having a size capable of accommodating the absorbent polymer particles in a swollen state when one or more absorbent polymer particles accommodated in the voids absorb liquid and swell. Thus, the problem is solved.

  Moreover, this invention solves the said subject by providing the absorbent article which comprises the said absorber.

  Further, the present invention is a method for producing an absorbent body comprising a wet papermaking containing pulp fibers as main fibers, wherein a large number of absorbent polymer particles are dispersed inside the wet papermaking, wherein the pulp Forming a wet fiber web by wet paper-making an aqueous dispersion containing fibers and the absorbent polymer particles; and drying the wet fiber web to reduce the swollen absorbent polymer particles in the wet fiber web The above-mentioned problems are solved by providing a method for producing an absorber having the following.

  ADVANTAGE OF THE INVENTION According to this invention, it is thin, has a liquid absorption property and intensity | strength sufficient practically, it is hard to produce the omission of an absorption polymer particle, and an absorbent article provided with this absorber is provided. Such an absorbent body and absorbent article can be designed so that they can be washed with water by appropriately selecting the absorbent polymer particles, and those designed products can be used after washing the absorbent article after use with water. Suitable for people who have a habit of disposal.

  Hereinafter, first, 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 a preferred embodiment thereof with reference to the drawings. 1 is a perspective view of a skin contact surface side of a sanitary napkin that is an embodiment of the absorbent article of the present embodiment, and FIG. 2 is a cross-sectional view schematically showing a cross section taken along line XX in FIG. FIG. 3 is a cross-sectional view schematically showing a part of the absorber shown in FIG.

  The napkin 1 of the present embodiment has a shape that is long in one direction as shown in FIG. 1, a liquid-permeable top sheet 2 that forms a skin contact surface, and a liquid impermeability that forms a non-skin contact surface. Or a hardly permeable rear sheet 3 and a liquid retaining absorbent 4 interposed between the two sheets 2 and 3. The absorbent body 4 has a shape that is long in one direction (substantially rectangular shape). The longitudinal direction of the absorbent body 4 matches the longitudinal direction of the napkin 1, and the center in the width direction of the portion of the napkin 1 that faces the excretion part of the napkin wearer. It is arranged in the department.

  In this specification, the skin contact surface is a surface directed toward the wearer's skin when the absorbent article is mounted, and the non-skin contact surface is the wearer's skin side when the absorbent article is mounted. Is the side facing the other side. The longitudinal direction is a direction along the longitudinal direction of the absorbent article or its constituent members, and the width direction is a direction orthogonal to the longitudinal direction.

  As shown in FIG. 2, the top sheet 2 is disposed on the skin contact surface of the absorber 4, and the back sheet 3 is disposed on the non-skin contact surface side of the absorber 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 upper and lower liquid-permeable core wrap sheets 5. Thus, covering the absorbent body 4 with the core wrap sheet 5 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 5, 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 have a size larger than that of the absorber 4, and extend outward in the width direction from both longitudinal edges 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 at a portion facing the excretion portion of the napkin wearer in the napkin 1 to form a pair of wing portions 6 and 6. Each wing portion 6 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 mounted. An adhesive portion (not shown) is provided for fixing the to the underwear. 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.

  As shown in FIG. 3, 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. The code | symbol 41 in FIG. 3 is the fiber which comprises the wet papermaking bodies 40, such as a pulp fiber. As will be described later, the wet papermaking body 40 is a fiber assembly manufactured using a conventionally known wet papermaking method. The wet papermaking body 40 contains pulp fibers and a large number of absorbent polymer particles 42, and the absorbent polymer particles 42 are liquid. It is obtained by drying a wet fiber web (wet fiber web) that is swollen by absorbing water.

  The wet papermaking body 40 has a single layer structure, that is, a single sheet, and is not a multilayer structure in which two or more layers are laminated as described in Patent Documents 1 to 3. The absorbent body 4 in this embodiment is composed of a single layer of wet papermaking body 40, and thus the absorbent body 4 has a single layer structure. The absorbent polymer particles 42 are not dispersed in the form of a layer in the wet papermaking body 40, but are three-dimensionally dispersed as shown in FIG.

  Inside the wet papermaking body 40, a large number of voids 43 surrounded by the constituent fibers 41 of the wet papermaking body 40 and containing one or more absorbent polymer particles 42 are formed. When the one or more absorbent polymer particles 42 accommodated in the gap 43 absorb the liquid and swell, the absorbent polymer particles 42 in a swollen state are accommodated. A large number of voids 43 are three-dimensionally dispersed in the wet papermaking 40 as in the dispersed state of the large number of absorbent polymer particles 42. As will be described later, the gap 43 is formed by utilizing swelling of the absorbent polymer particles 42 in the dry state due to liquid absorption and reduction due to drying of the absorbent polymer particles 42 in the swollen state. Accordingly, the size (volume) of the gap 43 is substantially equal to the size when one or more absorbent polymer particles accommodated in the gap absorbs the liquid and swells, and the shape of the gap 43 Is close to the swollen shape of one or more absorbent polymer particles contained in the void. In FIG. 3, 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.

  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, it is possible to effectively prevent the absorbent polymer particles 42 from falling off, and even if the absorbent polymer particles 42 having a low degree of swelling as described later are used, Insufficient strength is ensured, and sufficient practical strength is ensured. Therefore, the napkin is not easily swayed even after the absorbent body 4 absorbs the liquid, and the constituent fibers 41 are not easily disintegrated even when washed with water, and the absorbent body 4 can be washed with water. Moreover, the absorber 4 having such a configuration can be easily reduced in thickness and has excellent absorption performance and flexibility. On the other hand, an absorber by a dry process conventionally used in the technical field, for example, a sandwich-type absorber as described in Patent Document 2 (that is, an absorbent polymer particle between two upper and lower absorbent materials, Absorbers fixed by the adhesive force of the absorbent polymer particles themselves) and mixed fiber absorbents in which fibers and absorbent polymer particles are mixed in the air and stacked to absorb liquid and become wet. The constituent fibers are easily disintegrated and twisted easily when washed, and washing with water is impossible. In particular, the mixed fiber type absorbent body is liable to drop off the absorbent polymer particles even in a dry state.

  One or more absorbing polymer particles 42 are accommodated in the constituent fibers 41 in at least some of the numerous voids 43. Here, the absorption polymer particles are supported by the constituent fibers means that the absorption polymer particles 42 enter the gap 43 and the wet papermaking body 40 (absorbent body 4) is subjected to external stress. This refers to a state in which the absorbent polymer particles 42 are unlikely to move or drop off extremely. At this time, the absorbent polymer particles 42 adhere to the constituent fibers 41 due to their own stickiness, or the constituent fibers 41 are entangled or caught on the absorbent polymer particles 42. In this embodiment, the carrying state of the absorbent polymer particles 42 is a binder separate from the fibers 41 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 41 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.

  The absorbent polymer particle 42 has a degree of swelling from the viewpoint of reducing / removing redness caused by blood such as menstrual blood absorbed by the absorbent body 4 when the used napkin 1 (absorbent body 4) is washed with water. Is preferably used. Absorbent polymer particles with a high degree of swelling tend to take in hemoglobin in the blood, which is the main cause of redness, and it is difficult to remove hemoglobin taken in the inside of the absorbent polymer particles with water. It is not suitable for designing an absorber that can reduce or eliminate redness caused by stagnation. On the other hand, inconveniences due to the use of low-swelling absorbent polymer particles, for example, dropping of the absorbent polymer particles due to a decrease in the adhesiveness of the absorbent polymer particles themselves, the peel strength of the absorbent body, and the decrease in absorption performance are described above. This can be avoided by employing a wet papermaking body 40 having a large number of voids 43.

  As the absorbent polymer particles having a low degree of swelling, specifically, absorbent polymer particles having a centrifugal retention amount of 5 to 20 g / g, particularly 5 to 15 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%.

  Adjustment of the centrifugal retention amount of the absorbent polymer particles can be performed, for example, by adjusting the degree of surface cross-linking of the absorbent polymer particles. In general, when the degree of surface cross-linking of the absorbent polymer particles increases (surface cross-linking treatment proceeds), the centrifugal retention amount (water absorption magnification) tends to decrease. Specifically, for example, the surface retention-treated absorption polymer particles produced by a conventional method can be subjected to surface crosslinking treatment (post-crosslinking treatment) again to adjust the centrifugal retention amount to the above range. Is possible. In addition, the centrifugal retention amount can also be adjusted by increasing the degree of crosslinking of the entire absorbent polymer particles regardless of whether or not surface crosslinking is performed. The degree of crosslinking of the absorbent polymer particles used in the present invention (surface crosslinking degree or degree of crosslinking of the entire absorbent polymer particles) is at a higher level than that of ordinary absorbent polymer particles. In order to realize this, it is preferable to take a method such as increasing the amount of the crosslinking agent, increasing the reaction temperature, or taking a longer reaction time.

  In the present invention, when the absorbent polymer particles having a low degree of swelling are used as described above, the raw material for the absorbent polymer particles is an absorbent polymer particle having a low degree of swelling from the beginning (the amount of centrifugal retention is initially in the above range). Absorbing polymer particles having a high degree of swelling (absorbing polymer particles having a centrifugal retention amount outside the above range) can also be used. When the absorbent polymer particles having a high degree of swelling are used as the raw material of the absorbent body of the present invention, the absorbent polymer particles in the production process of the absorbent body include pretreatment for suppressing the swelling ratio in water, for example, divalent ions. Pretreatment such as absorption of an aqueous solution is preferably performed. By such pretreatment, the absorbent polymer particles having a high degree of swelling used as a raw material are subjected to metal cross-linking, whereby the absorbent polymer particles having a low degree of swelling are obtained. As described above, even when absorbent polymer particles having a high degree of swelling are used as a raw material, it is possible to produce an absorbent body including absorbent polymer particles having a low degree of swelling.

  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 41 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 bulky cellulose fibers occupying the constituent fibers 41 of the wet papermaking body 40 (the lower the proportion of NBKP used in combination), the higher the wet papermaking body 40 is and the higher the number of voids 43, and (Or the volume of each gap 43 is large). On the other hand, the lower the proportion of bulky cellulose fibers in the constituent fibers 41 of the wet papermaking body 40 (the higher the proportion of NBKP used in combination), the smaller the bulk of the wet papermaking body 40 and the lower voids (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. 4.22 (trade name) manufactured by Nexus Co., Ltd.], and the cross-sectional area and circumference of the measurement fiber are measured. 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 fiber 41 of the wet papermaking body 40, such as the pulp fiber, 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 the constituent fibers 41 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 41 of the wet papermaking body 40.

  The content of the fiber 41 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 41 is 30 to 90% by weight, particularly 40 to 70% by weight, It is preferable in terms of the balance between thinness and absorption performance.

  In addition to the fibers 41 and the absorbent polymer particles 42, the wet papermaking body 40 may further contain a wet paper strength enhancer such as polyamide / epichlorohydrin resin, dialdehyde starch, carboxymethyl cellulose, polyvinyl alcohol, or 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%.

Hereinafter, the napkin 1 of this embodiment is further demonstrated.
On the skin contact surface side (surface sheet 2 side) of the napkin 1, leakage preventing grooves 7 and 7 extending in the longitudinal direction of the napkin 1 are formed on both left and right sides in the longitudinal direction. Each leakage prevention groove 7 is formed by compacting and integrating the topsheet 2 and the absorber 4 from the topsheet 2 side by pressing means such as embossing. Each leakage prevention groove 7 has a substantially symmetrical shape with respect to the longitudinal center line of the napkin 1. The leakage prevention grooves 7 have their front and rear ends connected to each other, thereby forming a closed shape as a whole. By forming the leak-proof grooves 7 and 7, body fluids flowing outward in the napkin width direction are blocked, and leakage (lateral leakage) from the side of the napkin 1 is effectively prevented and cleaning is performed. Since the decomposition of the napkin at the time can be suppressed, it is easy to perform the washing operation and blood can be easily washed away. Furthermore, the fact that the leak-proof grooves 7 and 7 have reached the vicinity of the lower part of the absorber 4 is to prevent water from flowing through the entire absorber during cleaning and to prevent blood from remaining due to the absorber being biased. preferable.

  An end seal portion 8 is formed on the periphery of the napkin 1 at a position spaced outward from the absorber 4. The end seal portion 8 in the present embodiment is formed by integrating the top sheet 2 and the back sheet 3. More specifically, in the present embodiment, the top sheet 2 and the back sheet 3 extend from the peripheral edge portion of the absorber 4, and are joined to each other by a heat embossing process at the extended portions. Is formed. The end seal portion 8 has an effect of preventing the water absorbent material constituting the absorbent body 4 from flowing out when the napkin 1 is washed (when wet). It is preferable that the end seal portion 8 is not provided with a material that causes swelling or the like due to water used for the absorbent body 4 from the viewpoint of not separating each sheet material that is a constituent material of the end seal portion 8 during cleaning. . Further, the end seal portion 8 is formed by heat embossing with an adhesive such as hot melt disposed at a predetermined portion of the sheet material, thereby improving and stabilizing the flexibility of the seal portion and the seal strength when wet. From the viewpoint of making it more preferable.

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 present embodiment is used by being attached to an undergarment in the same manner as a normal sanitary napkin of this type. The napkin 1 of the present embodiment is composed of a single sheet-like wet papermaking body 40 in which the absorbent body 4 has a large number of voids 43 formed by utilizing the swelling of the absorbent polymer particles 42 and subsequent reduction. Therefore, although the degree of swelling (adhesiveness) of the absorbent polymer particles 42 is low, the absorbent polymer particles 42 are unlikely to fall off, and the absorber 4 has a practically sufficient strength. Even if the napkin 1 is washed with water, the fibers 41 and the absorbent polymer particles 42 do not easily fall apart, can be washed with water, and have excellent absorption performance and flexibility. Further, since the degree of swelling of the absorbent polymer particles 42 is low (that is, the centrifugal retention amount is 10 g / g or less), it is caused by blood such as menstrual blood absorbed by the absorbent body 4 by washing the napkin 1 (absorbent body 4). From such a viewpoint, the napkin 1 according to this embodiment can be preferably used for people who have a habit of washing the used napkin with water and then discarding it. Moreover, since the napkin 1 of this embodiment has the structure which the absorber 4 mentioned above, thickness can be designed thinly, it is not bulky, and it is excellent in portability and a feeling of mounting | wearing.

  Next, the manufacturing method of the absorbent body of the present invention will be described based on a preferred embodiment of the manufacturing method of the absorbent body 4 (wet papermaking body 40) in the above embodiment. 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 body 40 in water. The order of adding the aqueous dispersion liquid to the preparation tank of each component is not particularly limited, but the addition of the absorbent polymer particles 42 is performed immediately before wet papermaking of the aqueous dispersion liquid, that is, the aqueous liquid is added to a wet paper machine network (wire). ) Immediately before flowing over (just before the wire part in the paper making process). By adding the absorbent polymer particles 42 to the preparation tank at such timing, the dispersibility of the absorbent polymer particles 42 is increased, and as a result, the dispersive arrangement of the voids 43 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 42 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 configured by dispersing absorbent polymer particles 42 in a swollen state inside a wet fiber assembly. The swollen absorbent polymer particles 42 are surrounded by wet fibers 41.

  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, if necessary, the wet fiber web is pressed with a felt (blanket) and compressed from above and below to squeeze out the moisture in the web, and then in the dryer part, the drying means 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 42 that are in a swollen state by absorbing the liquid in the web are also dried. At that time, the absorbent polymer particles 42 in the swollen state are reduced in particle size as they are dried, and at the end of drying, the state substantially returns to the state before swelling (dried state before being added to the preparation tank). The state of the entanglement of the fibers 41 and the shape of the fiber structure formed thereby do not substantially change before and after drying, and as a result, a void 43 is formed around the reduced absorbent polymer particles 42. . Many of the reduced absorbent polymer particles 42 adhere to the fibers 41 in the vicinity of the interface of the voids 43 due to their own adhesiveness or tangling or catching of the fibers 41 in the voids 43 formed. In this way, the wet papermaking body 40 is obtained.

  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, in the above-described embodiment, the absorber 4 is composed of one layer of the wet papermaking body 40. However, the absorber 4 may have a multilayer structure in which two or more layers of the wet papermaking body 40 are laminated. . That is, the absorber according to the present invention may have a single layer structure or a multilayer structure. However, the wet papermaking body constituting the absorber is preferably a single layer structure, that is, a single sheet.

  Further, 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, but is used for disposable diapers, incontinence pads, urine-absorbing pads, pet diapers, pet sheets, etc. Is also applicable. 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, 1) used for the purpose of absorbing the wearer's sweat by being placed around the waist of the diaper, or 2) for example, a mixed fiber absorbent (fiber and absorbent polymer are mixed in the air) In the absorbent article comprising the main absorbent body as a main absorbent body, the main absorbent body is assisted and assisted by placing it 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 typical absorption.

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

[Example 1]
After 100 parts by weight of pulp fibers, 2 parts by weight of polyvinyl alcohol fibers (non-pulp fibers) and 16000 parts by weight of water were dispersed and mixed in the mixer, a wet paper strength reinforcing agent was further dried on the pulp fibers. The mixture was added to the mixer so that the resin component would be 0.44 parts by weight with respect to 100 parts by weight, and dispersed and mixed to obtain an aqueous dispersion. This aqueous dispersion was transferred to a wet paper machine filled with water, and immediately before wet paper making, the absorbent polymer particles were added to the aqueous dispersion and stirred, and then a wet fiber web was formed by a wet paper making method according to a conventional method. . Next, a filter paper is pressed against the wet fiber web to dehydrate it to remove water in the web appropriately. Then, the web is dried using a Yankee dryer and the dryer surface temperature is set to 130 ° C. to obtain a basis weight of 80 g. / M ² wet papermaking (absorber) was obtained.

  As the pulp fiber, bulky cellulose fiber “HBA” (trade name) manufactured by Warehauser and NBKP are used in a weight ratio of HBA: NBKP = 8: 2, and the non-pulp fiber is manufactured by Sansho. Fiber “Fibrybond” (trade name), sponge GX-3 (manufactured by Riken Green) as the wet paper strength enhancer, and commercially available sanitary napkin (trade name “Laurier” as the absorbent polymer particles). Absorbing polymer particles collected from Kao Corporation (centrifugal retention amount 32 g / g, average particle size 400 μm) were used. Further, the content of the absorbing polymer particles in the wet papermaking body (absorbent body) of Example 1 was 37.5% by weight with respect to the total weight of the wet papermaking body.

[Example 2]
In Example 1, the same procedure as in Example 1 was used, except that the surface-crosslinked absorbent polymer particles obtained by the following synthesis method (centrifuge retention amount was 9 g / g, average particle size 320 μm) were used. Thus, a wet papermaking body (absorber) was prepared and used as a sample of Example 2.

<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.

[Comparative Example 1]
A pulp sheet (NBKP manufactured by Warehauser) is passed through a sieve having an opening of 1 mm and loosened, and the pulp fibers passing through the sieve and the absorbent polymer particles used in Example 1 are alternately piled to obtain a mixed pile. The mixed fiber was pressed to obtain a so-called mixed fiber absorbent having a basis weight of 80 g / m ² , which was used as 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.

[Comparative Example 2]
Absorbent polymer used in Example 1 on one surface of a lower-layer mount having a basis weight of 20 g / m ² (wet papermaking of blended pulp containing NBKP and LBKP at a weight ratio of NBKP: LBKP = 9: 1). after the sprinkling basis weight was uniformly sprayed so that 30 g / m ^2, on top of the absorbent polymer particles, and a top layer mount (NBKP and LBKP having a basis weight of 30 g / m ² in weight ratio NBKP: LBKP = 9: 1 in a ratio of 9: 1 to obtain a laminate, and press the laminate to obtain a so-called sandwich-type absorber having a basis weight of 80 g / m ^2. A sample of Comparative Example 2 was obtained. 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.

About the sample (absorber) of the example and the comparative example, the thickness and the bending rigidity under a 49 Pa (0.5 g / cm ² ) load were measured according to the above-mentioned methods. Moreover, about the absorber of an Example and a comparative example, the absorption-disintegration rate at the time of drying and wetness, water washability (whether it can be washed with water), absorption time, and texture are measured and evaluated by the following methods, respectively. did. These results are shown in Table 1 below.

<Method of measuring the rate of absorber disintegration during drying>
Prepare a rectangular sample (absorber) 40 mm long and 40 mm wide, measure its weight (absorbent weight before treatment), put the absorber in a plastic bag filled with air (total weight before treatment) Measure weight). Then, with the plastic bag mouth closed, hold the plastic bag by hand and shake it 50 times quickly in the vertical direction, then remove the absorbent body from the plastic bag, and the weight of the plastic bag (bag weight after processing) Measure. And the absorber collapse rate at the time of drying is calculated | required by a following formula. The smaller the value of the absorber disintegration rate, the higher the shape retention of the absorber in the dry state, and the less the falling of the absorbent polymer particles, the higher the evaluation. The measurement of the post-treatment bag weight is carried out only when the absorbent body in the plastic bag after the shaking substantially maintains the original shape and size before being put into the plastic bag. If the initial shape and size were not maintained due to splitting or collapse, the test was not carried out, and it was set as “impossible to measure due to collapse”. Absorber disintegration rate during drying (%) = [(total weight before treatment−bag weight after treatment) / absorber weight before treatment] × 100

<Method of measuring the rate of absorber disintegration when wet>
In a petri dish, put a rectangular sample (absorber) 40 mm in length and 40 mm in width and 20 g of ion-exchanged water and leave it for 30 minutes, then remove the absorber and sandwich it with absorbent paper (Kim towel) from above and below. After placing a 2 kg weight and leaving it for 10 seconds, the weight is removed and the weight (g) of the absorbent is measured, and this is taken as the initial weight. Next, the absorbent body is put into a nylon mesh bag having a rectangular shape of 50 mm length and 50 mm width, and the mesh bag is immersed in ion-exchanged water being stirred at a stirring speed of 800 rpm for 30 seconds, and then the mesh bag is ion-exchanged. Take out the absorber from the water, place the 2kg weight between the top and bottom of the absorbent paper (Kim towel), leave it for 10 seconds, remove the weight and measure the weight (g) of the absorber. This is the weight after treatment. And the absorber disintegration rate at the time of wetness is calculated | required by a following formula. The smaller the value of the absorber disintegration rate, the higher the shape retention of the absorber in a wet state, and the less the polymer particles that fall off, the higher the evaluation. The post-treatment weight measurement is performed only when the absorbent body in the mesh bag taken out from the ion exchange water substantially maintains the shape and size at the time of the initial weight measurement, and the absorbent body is split. If the shape and size at the time of measurement of the initial weight were not maintained because they were broken or collapsed, it was not carried out, and it was set as “impossible to measure due to collapse”. Absorber disintegration rate when wet (%) = {(initial weight−weight after treatment) / initial weight} × 100

<Evaluation method of water washability>
The evaluation of wettability is based on two indicators: the state of the absorbent body after washing (whether the constituents of the absorbent body are broken apart) and the degree of reduction due to reddish water washing caused by the absorbed blood. use. The former evaluation of the wettability is that in <Measurement method of absorbent disintegration rate when wet>, when the mesh bag is taken out from the ion-exchanged water, the inside of the mesh bag is visually observed, and the absorber disintegrates. It is determined whether the shape before immersion in ion-exchanged water is not retained (does not collapse), or the absorber is peeled off or collapsed apart and does not retain the original shape (collapse) By doing. Moreover, the evaluation of the wettability by the latter is performed by the red degree a ^* value measured by the following method. The smaller the a ^* value, the lower the redness of the red part stained with blood, and if the a ^* value is 0 or less, it means that the blood has been washed away with water.

<Measurement method of red degree a ^* value>
A rectangular sample (absorber) 40 mm long and 40 mm wide is placed in a 50 mm long and 50 mm wide nylon mesh bag, and the mesh bag and 10 g of horse blood are placed in a petri dish and left for 30 minutes. The mesh bag is taken out of the petri dish and washed with water for 2 minutes. Wash the mesh bag for 2 minutes with the following procedure. Prepare four beakers, stir each with about 800 ml of ion-exchanged water, and immerse the mesh bags containing the absorbers in the ion-exchanged water in the beaker (stirring speed: about 500 rpm). Let The soaking time is 15 seconds for the first two beakers, 30 seconds for the third beaker, and 1 minute for the fourth beaker. After being immersed in the fourth beaker, the mesh bag is taken out from the ion exchange water, and the absorber is taken out. The spectrophotometric colorimeter is used for the five most intense red points of the red portion stained with horse blood in the absorber. Is used to measure the redness degree a ^* value. The average of the three measurement values obtained by removing the maximum value and the minimum value from the five measurement values is defined as the red degree a ^* value of the absorber. When measuring the a ^* value, the measurement sample and the spectral color difference meter are brought into close contact with each other so that external light does not enter. As the spectral color difference meter, a simple spectral color difference meter “NF333” (pen type detector) manufactured by JASCO Corporation can be used.

<Measurement method of absorption time>
A rectangular sample (absorber) having a length of 40 mm and a width of 40 mm is placed on an absorbent paper (Kim towel), and an acrylic plate with a cylindrical injection portion is placed on 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 1 g of blood is injected from the cylindrical injection portion and absorbed by the absorber. The time (seconds) from when the blood reached the surface of the absorber until the entire amount of 1 g was absorbed by the absorber was measured, and this was taken as the absorption time. The absorption time was measured twice for each sample, and the average value thereof was taken as the absorption time of the sample. The smaller the value of this absorption time, the faster the absorption speed and the higher the evaluation.

<Texture evaluation method>
Five panelists actually touched the sample (absorber) and performed sensory evaluation. The rating is 5 levels, 5: soft, 4: slightly soft, 3: not say either 2: slightly hard, 1: hard, and the score is converted to 5 points. Soft and hard when less than 3 points.

  The absorbent bodies (wet papermaking bodies) of Examples 1 and 2 were obtained by dehydrating and drying a wet fiber web, and a large number of the above-described voids were formed therein. As is clear from the results in Table 1, the absorbent bodies of Examples 1 and 2 having such a structure have a low rate of absorber collapse when dried and wet. It can be seen that (shape retention) is sufficient. Moreover, the absorbers of Examples 1 and 2 were thin, had sufficient absorption performance, and maintained flexibility. Furthermore, since the absorbent body of Example 2 mainly uses absorbent polymer particles having a low degree of swelling (small amount of centrifugal retention), it can be seen that the absorbent body is excellent in water washability and the attached blood can be washed away with water. . On the other hand, in the absorbers of Comparative Examples 1 and 2, the above-described voids are not substantially formed, and there is room for improvement particularly in terms of prevention of the dropping of the absorbent polymer particles and strength (shape retention). I understand that.

FIG. 1 is a perspective view showing a skin contact surface side (surface sheet side) of a sanitary napkin that is an embodiment of the absorbent article of the present invention. 2 is a cross-sectional view schematically showing a cross section taken along line XX of FIG. FIG. 3 is a cross-sectional view schematically showing a part of the wet papermaking product shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sanitary napkin 2 Top sheet 3 Back sheet 4 Absorber 5 Core wrap sheet 6 Wing part 7 Leak-proof groove 8 End seal part 40 Wet paper-making body 41 Fiber 42 Absorbing polymer particle 43 Void part

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,
A large number of voids surrounded by the constituent fibers of the wet papermaking and containing one or more absorbent polymer particles are formed inside the wet papermaking, and the voids are formed in the voids. An absorbent body having a size capable of accommodating the absorbent polymer particles in a swollen state when one or more of the contained absorbent polymer particles swells by absorbing liquid.   The absorbent body according to claim 1, wherein a centrifugal retention amount of the absorbent polymer particles is 5 to 20 g / g.   The wet papermaking product is obtained by drying a wet fiber web containing the pulp fibers and a large number of the absorbent polymer particles, and the absorbent polymer particles are swollen by absorbing the liquid. The absorber according to claim 1 or 2.   The absorbent article which comprises the absorber in any one of Claims 1-3. A method for producing an absorbent body comprising a wet papermaking containing pulp fibers as a main fiber, wherein a large number of absorbent polymer particles are dispersed and arranged inside the wet papermaking,
Wet paper making an aqueous dispersion containing the pulp fibers and the absorbent polymer particles to form a wet fiber web; and drying the wet fiber web to reduce the swollen absorbent polymer particles in the wet fiber web The manufacturing method of the absorber which has a process to make.

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