TWI797350B - absorbent article - Google Patents

Abstract

The object of the present invention is to provide the impression of a skin-friendly product using natural materials by the absorber having the original color of wood, and the absorber can achieve moderate adhesion and liquid absorption to the surface sheet. absorbent article. An absorbent article (310) includes: a liquid-absorbent core (321); and a core-covering sheet (322) covering the liquid-absorbent core. The core material covering sheet (322) is the first coating part (325) on the skin-facing side of the coating liquid-absorbent core material (321), has a lignin component content rate higher than that of the surrounding area, and has a higher content of lignin than the surrounding area, and has a higher content in the plan view. Scattered multiple high lignin regions (352). The content rate of the lignin component of the core material covering sheet is higher than that of the liquid-absorbent core material (321).

Description

absorbent article

The present invention relates to absorbent articles, and more specifically, to light incontinence pads, panty liners, sanitary napkins, secretion-absorbing pads, urine-absorbing pads, after-use pads for adults and children Absorbent articles such as disposable diapers.

Conventionally, absorbent articles comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber interposed between the front and back sheets are known. For example, Patent Document 1 discloses an absorbent article including an absorbent body of wood pulp fibers not subjected to lignin removal treatment.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 56-53745

(Problems of the 1st and 2nd inventions)

In the absorbent article disclosed in Patent Document 1, the wood pulp fibers contained in the absorbent body are not subjected to lignin removal treatment, so that the wood pulp fibers have the original natural color of natural wood. When the absorbent body is seen through the surface sheet, the The wearer and the like can give the impression of a nature-based product using natural materials.

However, among the components of cellulose, hemicellulose, and lignin mainly contained in wood or non-wood pulp, the cellulose component has a high degree of hydrophilicity, whereas lignin has a low hydrophilicity and is also called It is hydrophobic. Therefore, lignin that has not been subjected to lignin removal treatment has high hydrophobicity, and when the pulp fibers are distributed throughout the absorbent body, body fluids cannot be absorbed and held from the surface of the absorbent body.

The first and second inventions are improvements of the conventional inventions, and an object of the present invention is to provide an absorbent article having an absorbent body which has the original natural color of wood and can sufficiently absorb and retain bodily fluids.

(The solution of the first invention)

The first invention relates to an absorbent article comprising a liquid-permeable top sheet on the side facing the skin; a liquid-impermeable back sheet on the side not facing the skin; between absorbers.

In the absorbent article of the first invention, the absorbent system has a liquid-absorbent core; and at least the skin is covered with the liquid-absorbent core. The core material covering sheet on the opposite surface side, the core material covering sheet is the first covering part on the skin-facing surface side that covers the liquid-absorbent core material, has a lignin component content higher than that of the surrounding area, and In the plurality of high-lignin regions dispersed in a plan view, the lignin content of the core material covering sheet is higher than that of the liquid-absorbent core material.

The absorbent article of the first invention includes the following embodiments.

(1) The content rate of the lignin component of the aforementioned core material covering sheet is 0.2 to 10%.

(2) The aforementioned core material covering sheet has a wrinkle ratio of 7 to 20%, and a texture index of 50-300.

(3) The core covering sheet includes wood or non-wood pulp fibers, and the liquid-absorbent core includes cellulose fibers.

(4) The aforementioned liquid-absorbent core material contains particles having odor-adsorbing properties.

(5) The absorption system has a plurality of concave portions that are concave from the skin-facing side toward the non-skin-facing side.

(6) The core covering sheet further has a second covering portion covering the non-skin-facing surface side of the liquid-absorbent core, and the plurality of high lignin regions are located in the second covering portion.

(7) The aforementioned surface sheet contains cotton fibers, and the Klemm water absorption of the aforementioned core material covering sheet is higher than the Klemm water absorption of the aforementioned surface sheet higher.

(8) The surface sheet has a first part and a second part having a denser fiber density than the first part, the first part is joined to the high lignin region, and the second part is joined to the low lignin region.

(9) The above-mentioned surface sheet has a multi-layer structure, and the layer on the side facing the skin is mainly composed of cotton fibers.

(10) The Gramm water absorption of the aforementioned surface sheet is lower than that of the aforementioned core material covering sheet.

(solution means of the second invention)

The second invention relates to an absorbent article comprising a liquid-permeable top sheet on the side facing the skin; a liquid-impermeable back sheet on the side not facing the skin; between absorbers.

In the absorbent article of the second invention, the absorbent system has a liquid-absorbent core; and a core-covering sheet covering at least the skin-facing side of the liquid-absorbent core, and the core-covering sheet has a core covering sheet covering the absorbent core. The first coating part of the aforementioned skin-facing side of the liquid core material, the aforementioned first coating part and the aforementioned surface sheet are bonded to each other via an adhesive, and the content of the lignin component of the aforementioned core material coating sheet is higher than that of the aforementioned absorbent The content rate of the lignin component of the liquid core material is higher, and in the aforementioned thickness direction, there is A plurality of recesses extending to a part of the aforementioned liquid-absorbent core material.

The absorbent article of the second invention includes the following embodiments.

(1) The core covering sheet further has a second covering portion covering the non-skin-facing surface side of the liquid-absorbent core, and the second covering portion and the back sheet are bonded to each other via an adhesive,

(2) The concave portion is a concave portion with a bottom, and part of the surface sheet, the core material covering sheet, and the liquid-absorbent core material are compressed, and the thin-walled portion in the concave portion is compared to The thick-walled portion without the aforementioned concave portion has a higher density.

(3) The concave portion is an opening that penetrates the top sheet and the absorber in the thickness direction.

(4) The aforementioned adhesive system is a SIS-based hot-melt adhesive.

(5) The aforementioned core material covering sheet has a plurality of high lignin regions that have a lignin component content higher than that of the surrounding region and are dispersed in a plan view.

(6) The aforementioned core material covering sheet has a wrinkle ratio of 7 to 20%, and a texture index of 50-300.

(7) The surface sheet has a first part and a second part having a denser fiber density than the first part, the first part is joined to the high lignin region, and the second part is joined to the peripheral region.

(8) The above-mentioned surface sheet has a multi-layer structure, and the layer on the side facing the skin is mainly composed of cotton fibers.

(10) The Clem water absorption of the above-mentioned surface sheet is covered by the above-mentioned core material Flakes of Clem have lower water absorption.

In at least one embodiment of the absorbent article of the first invention, since the absorber has the original color tone of wood, the impression of a skin-friendly product using natural materials can be given, and the absorber can achieve an appropriate fit with the surface sheet. Adhesiveness and liquid absorption.

In at least one embodiment of the absorbent article of the second invention, since the core covering sheet contains a large amount of lignin components, it has a natural color tone derived from natural materials such as wood, and since it has a natural color in the thickness direction. Since the surface sheet continuously extends to a plurality of recesses in a part of the liquid-absorbent core, body fluids can be quickly absorbed and retained.

310: Physiological sanitary napkins (absorbent articles)

310a: 1st edge

310b: 2nd edge

310c: 1st side edge

310d: 2nd side edge

311: surface flakes

312: back sheet

314: side sheet

317: side edge

320: absorber

320a: first edge

320b: the second edge

320c: 1st side edge

320d: 2nd side edge

321: Absorbent core material

322: core material covering sheet

322a, 322b: both side edges

323: Overlap

325: 1st Covering Department

326: The second covered part

331: central area

340: pulp fiber

341: bleached pulp fiber

342: Unbleached pulp fiber

351: low lignin area

352: high lignin area

360: concave part

380: Disposable paper diapers (absorbent articles)

402: The opposite side of the skin

403: Non-skin-facing side

410: Physiological sanitary napkins (absorbent articles)

410a: 1st edge

410b: 2nd edge

410c: 1st side edge

410d: 2nd side edge

411: surface flakes

412: back sheet

414: side sheet

417: side edge

418: wing part

420: absorber

420a: 1st edge

420b: 2nd edge

420c: 1st side edge

420d: 2nd side edge

421: Absorbent core material

422: core material covering sheet

425: 1st Covering Department

426: The second covered part

431:Central area

440: pulp fiber

441: bleached pulp fiber

442: Unbleached pulp fiber

451: low lignin area

452: high lignin area

460: concave part

460a: 1st concave part

460b: 2nd concave part

460c: 3rd concave part

480: Disposable paper diapers (absorbent articles)

The drawings show specific embodiments of the first and second inventions, and include not only essential structures of the invention but also optional and ideal embodiments.

Fig. 1 is a plan view of a sanitary napkin according to a first embodiment, which is an example of the absorbent article of the first invention, viewed from the front side.

Fig. 2 is a plan view of the absorber viewed from the back side.

Fig. 3 is a sectional view of line III-III in Fig. 1 .

Fig. 4 is a plan view of the absorber.

FIG. 5 is a partially enlarged view of the area surrounded by the V line in FIG. 4 .

Fig. 6 is a partial enlargement of the area surrounded by the one-point chain line VI-VI line in Fig. 3 big picture.

Fig. 7 is a plan view of a sanitary napkin according to a second embodiment of the first invention.

Fig. 8(a) is a sectional view of VIII(a)-VIII(a) in Fig. 7 . Fig. 8(b) is a cross-sectional view similar to Fig. 8(a) of an example of a modified example of the absorber according to the second embodiment of the first invention.

Fig. 9 is a plan view of an absorbent article according to a third embodiment of the first invention.

Fig. 10 is a plan view of a sanitary napkin as the first embodiment of the absorbent article of the second invention viewed from the front side.

Fig. 11 is a plan view of a sanitary napkin viewed from the back side.

Fig. 12 is a plan view of the absorber.

Fig. 13 is a cross-sectional view along line XII in Fig. 12 .

Fig. 14 is a cross-sectional view similar to Fig. 13 of an example of a modified example of the absorber.

Fig. 15 is a plan view of an absorber of a sanitary napkin according to a second embodiment of the second invention.

Fig. 16 is a partially enlarged view of the area surrounded by line XVI in Fig. 15 .

Fig. 17 is a sectional view similar to Fig. 13 of a sanitary napkin according to a second embodiment of the second invention.

Fig. 18 is a plan view of an absorbent article according to a third embodiment of the second invention.

(the first invention) (1st Embodiment of 1st invention)

The following embodiments of the first invention relate to absorbent articles shown in the drawings, and include not only the indispensable configurations of the invention but also optional and desirable configurations. Hereinafter, an embodiment of the sanitary napkin 310 which is an example of the absorbent article of the present invention will be described with reference to the drawings. The sanitary napkin 310 has a vertical direction Y, a horizontal direction X, and a thickness direction Z.

As shown in Figures 1 to 3, the sanitary napkin 310 has a longitudinal centerline P that divides its width in half and a transverse centerline Q that divides its length in half, and includes: the skin-facing surface (inner surface) side and the non-skin-facing surface (outer surface) side on the opposite side; first and second end edges 310a, 310b of convex shape; 1 and 2 side edges 310c, 310d; a liquid-permeable surface sheet 311 positioned on the skin-facing side; a liquid-impermeable back sheet 312 positioned on the non-skin-facing side; and between the two sheets 311, 312 The liquid-absorbent absorbent body 320. The surface sheet 311 and the absorber 320 are bonded to each other by conventional bonding means such as hot-melt adhesive to form the liquid-absorbent layer 313 .

In addition, although not shown, in order to improve the softness of the sanitary napkin 310 , an intermediate sheet made of fiber nonwoven fabric with a high bulkiness may be arranged between the surface sheet 311 and the absorber 320 . In addition, between the absorber 320 and the back sheet 312, in order to suppress leakage of bodily fluids, a leak-proof sheet preferably made of air-permeable and liquid-impermeable non-woven fabric or a plastic film may be disposed.

The absorber 320 has: a first edge facing the first edge 310a; The end edge 320a and the second end edge 320b opposite to the second end edge 310b; and the first and second side edges 320c, 320d extending in the longitudinal direction between the first and second end edges 320a, 320b. The front and back sheets 311, 312 extend outward from the outer periphery of the absorber 320, and on the skin-facing side of the surface sheet 311, a pair of sides extending in the longitudinal direction Y is disposed so as to face each other in the horizontal direction. Sheet 314. The pair of side sheets 314 are bonded to the surface sheet 311 through known bonding means or side joints (not shown) formed by bonding means. Although not shown in the figure, in order to form a leak-proof wall rising toward the body side in the worn state, the elastic material extending in the longitudinal direction Y may be arranged so as to be contractible in the stretched state on the side sheet 314 . In addition, the side joining portion for fixing the side sheet 314 may also be a seal line extending in the longitudinal direction Y with design elements such as floral patterns and geometric patterns.

The sanitary napkin 310 is formed of a surface sheet 311, a back sheet 312, and a side sheet 314, and extends toward the lateral direction X outside the longitudinal direction Y of the first and second edges 320a and 320b of the absorbent body 320. Both end portions 316 ; and both side edge portions 317 extending in the longitudinal direction Y on the outer side in the transverse direction X of the first and second side edges 320 c and 320 d of the absorber 320 . In the central portion of the sanitary napkin 310 in the longitudinal direction Y, there is a wing portion 318 convex outward in the lateral direction X and formed by a part of both side edge portions 317 . Also, the sheets 311 , 312 , and 314 laminated on each other are bonded to each other through the peripheral seal portion 319 present along the outer peripheral edge of the sanitary napkin 310 .

As shown in FIG. 2 , a plurality of fixing regions 330 are arranged on the back side of the sanitary napkin 310 . A plurality of fixation areas 330 are used to fix the sanitary napkin 310 on clothing such as underwear, by coating Formed in a plurality of linear adhesives, pressure-sensitive adhesives, etc. extending in the longitudinal direction Y. The fastening region 330 has a central region 331 extending in the longitudinal direction Y in a region overlapping with the absorber 320 , and side regions 332 located in the flap portion 318 . The fixation area 330 is covered by a separator (not shown) made of plastic film.

The surface sheet 311 can be formed of various liquid-permeable fiber non-woven fabrics, such as air-through fiber non-woven fabrics with a mass of about 15-45 g/m ² , porous plastic films, or such laminated sheets. Also, the back sheet 312 may be formed of a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fiber non-woven fabric, a laminated sheet of these, or the like. The side sheet 314 can be made of the same sheet material as the surface sheet 311 . However, in order to effectively prevent lateral leakage of body fluids, it is better to use thin sheets with hydrophobic or water-repellent properties.

As the surface sheet 311, a sheet having unevenness on the surface side can also be used. The surface of the sheet is formed by a plurality of concave portions and a plurality of convex portions arranged alternately in the longitudinal direction Y or the lateral direction X. As a method for forming the plurality of convex portions and concave portions, for example, controlling the amount of fibers can be mentioned. A method of forming a portion with a low bulkiness and a portion with a high bulkiness, a method of forming a concave portion by embossing/debossing, a method of forming a concave-convex shape, and the like. The convex portion and the concave portion are arranged so that the fiber density is different from each other so that one is sparse and the other is dense. By joining the part where the fibers are sparsely arranged (first part) to the high lignin region 352 of the core covering sheet 322 described later, the joint strength becomes higher. Part 2) joins the low lignin area 351 for higher liquid absorption.

Also, even if menstrual blood is excreted repeatedly in a short period of time Furthermore, by temporarily collecting menstrual blood in the concave portion, it is possible to suppress lateral leakage of menstrual blood from the surface of the surface sheet 311 and between the surface sheet 311 and the core covering sheet 322 . In addition, it is preferable that a part of the concave portion of the surface sheet 311 is substantially (continuously or discontinuously) surrounded by a press portion forming a press groove, a compressed concave portion formed by embossing, and the like. In this case, it is possible to suppress leakage of bodily fluid collected in the concave portion in the horizontal direction X and the vertical direction Y. In addition, when the surface of the surface sheet is concave-convex, since the light brown core covering sheet 322 is recognized as darker in the concave portion than in the convex portion from the surface viewing angle, a change in color may also occur. decorative effect.

The outer peripheral seal portion 319 can be bonded by an adhesive, bonded by conventional welding means such as ultrasonic welding, thermal welding, laser welding, high-frequency welding, and bonded by embossing. , or in combination. Also, the sheets 311 , 312 , and 314 stacked in the thickness direction Z are bonded to each other via an adhesive such as a hot-melt adhesive. As the coating method of the hot melt adhesive, for example, various known coating methods such as screw coating, coater coating, curtain coater coating, and spray coating can be mentioned.

As shown in FIGS. 3 and 4, the absorber 320 has a liquid-absorbent core material in which superabsorbent polymer particles (SAP) are mixed with cellulosic fibers such as fluff wood pulp and rayon fibers, and shaped into a predetermined shape. 321; and in order to improve its shape retention and liquid diffusivity, the liquid-permeable core material covering sheet 322 that covers the entire liquid-absorbent core material 321.

The size of the core material covering sheet 322 in the longitudinal direction Y is larger than that of the liquid-absorbent core material in the longitudinal direction Y. The transverse direction X of the core material 321 The bottom side of the central part exists in an overlapping manner. By folding the side edges 322a and 322b together, an overlapping portion formed by stacking the side edges 322a and 322b extending in the longitudinal direction Y is formed in the central part of the absorber 320 in the transverse direction X. 323.

The core covering sheet 322 has a first covering part 325 covering the skin-facing side of the liquid-absorbent core 321 , and a second covering part 326 covering the non-skin-facing side of the liquid-absorbing core 321 . In this embodiment, the core material covering sheet 322 is formed by one continuous sheet, but it is also possible to form the first core material covering sheet forming the first covering part 325 and the first core material covering sheet differently and The second core material covering sheet forming the second covering part 326 is constituted.

As shown in FIG. 5 , the core covering sheet 322 is formed of various known fiber non-woven fabrics or thin papers, and is mainly composed of pulp fibers 340 . The pulp fibers 340 of the core covering sheet 322 have: bleached pulp fibers 341 subjected to a lignin removal treatment; and unbleached pulp fibers 342 not subjected to a lignin removal treatment. Here, the pulp fiber 340 includes not only wood pulp fibers obtained from coniferous trees or hardwoods, but also non-wood pulp fibers such as cotton linters, Manila hemp, kenaf, rice straw, bamboo, and bananas.

Also, the core covering sheet 322 may have a first layer (upper layer or lower layer) made of hydrophilic fibers such as regenerated cellulose fibers such as rayon fibers or semi-synthetic cellulose fibers, A multi-layer structure formed by the second layer (lower layer or upper layer) composed of lignin-removed unbleached pulp fibers 342 . In this case, as will be described later, even if the second layer has a low lignin region 351 and a high lignin region 352 In the case of the island-in-the-sea structure, the body fluid can be sufficiently diffused in the first layer, so that the occurrence of the diffusion pattern of the body fluid in the core material covering sheet 322 as a whole can be suppressed. Thereby, even after bodily fluid has been absorbed multiple times, it is possible to suppress a decrease in bonding property with the top sheet 311 and maintain good liquid absorbency.

Pulp fiber 340 is generally processed by adding tablets to the raw material chips and boiling under high temperature and pressure to digest the lignin (the first stage of the lignin removal process) and remove foreign matter in the pulp after the pulp fiber 340 is processed. Stencil process, oxygen exposure process that decomposes lignin remaining in the digestion process with oxygen (the second stage of lignin removal treatment), and bleaching process that uses multiple chemicals to bleach pulp, forming bleached 341 bleached pulp fibers. The unbleached pulp fiber 342 is the first stage of the lignin removal process in each of these processes, and only undergoes a steaming process and a screen process, and a certain degree of lignin removal process is performed.

The lignin content of the unbleached pulp fiber 342 of the present invention is 0.2 to 10.0%.

The lignin content rate of the unbleached pulp fiber 342 can be measured as follows.

<Measuring method of lignin content> Quantification of ADF

Reagent: acidic detergent solution (dissolve 10g of hexadecyltrimethylammonium bromide in 500mL 1N sulfuric acid); acetone; as a defoamer, decahydronaphthalene (option).

<measurement sequence>

Weigh 300g of the sample, put it into a 50mL Erlenmeyer flask, and then add 30mL of acidic substance and solution. Then cover it with aluminum foil, put the Erlenmeyer flask into boiling water, and decompose for 60 minutes. After decomposition, move to a Gucci crucible covered with glass fiber filter paper (GA-200) for suction filtration, and wash the residue with hot water and acetone. After air-drying, heat-drying is carried out. In addition, after drying, the weight was weighed, and the weight minus the ash was used as ADF, but the ash after quantifying the lignin could not be used here.

lignin quantification

Reagent: 72% sulfuric acid

<measurement sequence>

Add a few drops of 72% sulfuric acid to the dried Gooch crucible to make the whole thing wet, then add sulfuric acid about twice the amount of ADF, add sulfuric acid appropriately every hour, and let it stand for 3 to 4 hours. Then, perform suction filtration and wash with hot water until the furnace liquid does not become acidic. After air drying, it was heat dried and weighed. The Gooch crucible was ashed at 550°C to obtain the ash content.

The first covering part 325 of the core covering sheet 322 has: A low lignin region (low lignin content region) 351 in which the content rate of the lignin component is low; and a high lignin region (high lignin content region) 352 in which the lignin component content rate is low in the lignin region 351 . The low lignin region 351 is mainly formed by aggregating bleached pulp fibers 341 , and the high lignin region 352 is formed mainly by aggregating unbleached pulp fibers 342 . In the top view of the first coating portion 325 of the core material covering sheet 322, the low lignin region 351 is a peripheral region located in a wide range of the outer surface of the core material covering sheet 322, while the high lignin region 352 is arranged Pairs of low lignin regions 351 exist scattered. Also, due to this arrangement, the entire core covering sheet 322 or at least the first covering portion 325 can be said to have a sea-island structure with the low lignin region 351 as the sea and the high lignin region 352 as the island.

Since the core covering sheet 322 has a plurality of high lignin regions 352, the whole has a light brown color from plant materials such as wood. The other sheets 311, 312, and 314 other than the core material covering sheet 322 are made white as a whole by kneading a white pigment such as titanium dioxide into the constituent fibers. And/or from the rear view, it can be easily identified from other sheets 311 , 312 , 314 through.

The core covering sheet 322 of this embodiment is formed into a thin sheet by entangling a mixture of bleached pulp fibers 341 and unbleached pulp fibers 342 during the papermaking process. The quality area 352 is mainly equipped with unbleached pulp fibers 342, therefore, the boundary between the two areas 351, 352 is not clear, there is no law to clearly distinguish. In addition, in this way, as a method of forming the core material covering the entire outer surface of the sheet 322 so that the high lignin regions 352 are dispersed in the low lignin region 351, for example, the mixing method and mixing ratio of the pulp fibers 341 and 342 can be appropriately adjusted. , the transport speed of the transport conveyor during production, the nozzle diameter when the pulp fiber 340 is deposited on the conveyor through the air injected from a plurality of nozzles, the air volume and wind speed of the blown air, and the like.

Since the two regions 351 and 352 are formed by adjusting various conditions in the manufacturing process, it can also be said that a part of the low lignin region 351 contains unbleached pulp fibers 342 and a part of the high lignin region 352 contains bleached pulp fibers 341 . Therefore, the low lignin region 351 and the high lignin region 352 are not only formed by bleached pulp fibers 341 and unbleached pulp fibers 342, but also include other fibers other than pulp fibers, for example, in the pulp fibers in the low lignin region 351 The content rate of the bleached pulp fiber 341 is 50-100%, and the content rate of the unbleached pulp fiber 342 in the pulp fiber of the high lignin region 352 is 50-100%.

Since the high lignin region 352 refers to a region with a higher lignin content than the low lignin region 351 in the peripheral region of the core covering sheet 322 , it may not be formed using a sheet mixed with bleached pulp fibers 341 and unbleached pulp fibers 342 . For example, the high lignin region 352 in which the lignin content is higher than the surrounding region is formed by sporadically infiltrating a lignin component-containing liquid into a fibrous nonwoven fabric sheet formed of rayon fiber, synthetic fiber, or the like.

The core cover sheet 322 has a plurality of high lignin regions 352 mainly composed of unbleached pulp fibers 342, so compared to using only In the case of the core covering sheet made of unbleached pulp fibers, it has a light brown (log color) from plant materials in the surface view, and can give the wearer or wearing aids the affinity of using natural materials. The impression of skin products. Also, since the core covering sheet 322 has a light brown color, when excreted menstrual blood passes through the surface sheet 311 and is absorbed and held by the absorbent body 320, redness of the menstrual blood can be suppressed. Thereby, it is possible to suppress the feeling of disgust of directly recognizing menstrual blood, and to alleviate the mental anxiety caused by recognizing the redness of menstrual blood, for example, for a wearer at the beginning of menstruation. In addition, since the lignin component has an antibacterial effect, the multiplication of miscellaneous bacteria after use can be suppressed, and it can be disposed of hygienically.

In order for the core material covering sheet 322 to exhibit the natural appearance, the suppression of menstrual redness and certain antibacterial effects, the content of lignin in the core material covering sheet 322 is preferably 0.2-10%. When the lignin component content rate of the core material covering sheet 322 is less than 0.2%, the light brown color of the core material covering sheet 322 becomes so light that it is visually indistinguishable from the other white sheets 311, 312, 314. degree of risk. In addition, when the lignin component content rate of the core material covering sheet 322 exceeds 10%, the color of the lignin component becomes darker, which may damage the natural appearance of the natural material, and it becomes difficult to recognize the redness of menstrual blood. , there is a risk of not being able to correctly grasp the amount of menstrual blood.

Generally, in addition to the shape retention of the liquid-absorbent core material, the core-covering sheet also has the function of absorbing and diffusing the body fluid passing through the surface sheet while migrating it to the liquid-absorbent core material. Therefore, it is ideal to use a hydrophilic Flakes. Since the unbleached pulp fibers 342 of the high lignin region 352 are It contains a lot of lignin components, so that the degree of hydrophilicity is low, and it can be said to be relatively hydrophobic. Therefore, for example, in the case where the entire first covering part 325 is formed by the high lignin region 352, it may not be able to absorb and maintain permeation through the high lignin region 352. If the menstrual blood covered the surface sheet 311, the menstrual blood cannot quickly migrate to the liquid-absorbent core material 321.

As shown in FIG. 6 , since the first coating portion 325 of the core material covering sheet 322 has a low lignin region 351 and a plurality of high lignin regions 352 scattered around it, from a cross-sectional perspective, these two regions 351, The 352 lines are interactively presented in the horizontal direction X. The high lignin regions 352 are scattered and arranged in the low lignin region 351 , so not only in the horizontal direction X, but also in the vertical direction Y, the low lignin regions 351 and the high lignin regions 352 are alternately arranged.

In this way, in the cross-sectional view of the first covering part 325, the low lignin region 351 and the high lignin region 352 are alternately located in the horizontal direction X and the vertical direction Y, therefore, the menstrual blood passing through the surface sheet 311 can be sucked into the hydrophilic area. The low lignin region 351 quickly migrates to the liquid-absorbent core 321 and is absorbed and retained, with a desired absorption speed.

In addition, in the hydrophilic low lignin region 351, the bleached pulp fiber swells due to the absorption of menstrual blood, and at the bonding interface between the surface sheet 311 and the core covering sheet 322 bonded by the hot-melt adhesive, the bonded part will be peeled off. There is a risk of lower joint strength. In addition, the high lignin region 352 is less hydrophilic than the lignin region 351 and has hydrophobicity. Therefore, it is not easy to absorb menstrual blood and swell, and there will be no peeling of the joint part. interface bonding strength The lower lignin region 351 becomes higher.

Therefore, compared with the case where the entire core material covering sheet 322 is formed of the low lignin region 351, the bonding strength between the core material covering sheet 322 and the surface sheet 311 becomes higher, and it is possible to suppress detachment from the absorber 320 of the surface sheet 311 during wearing, float etc. In addition, if the amount of adhesive is increased in order to increase the joint strength of the two sheets 311, 322, the rigidity of the sheets may increase and the flexibility and liquid permeability may decrease, but this disadvantage does not occur.

In addition, the liquid-absorbent core material 321 mainly includes SAP particles and bleached fluff pulp, and also has cellulose fibers as an option. Therefore, it does not contain unbleached pulp fibers 342, but rather than the core material covering sheet 322. , the lignin content becomes lower. Therefore, the menstrual blood absorbed by the surface sheet 311 and diffused in the core covering sheet 322 is easier to migrate rapidly when absorbed by the liquid-absorbent core 321 with a higher degree of hydrophilicity than the core covering sheet 322 .

In this way, in this embodiment, the core material covering sheet 322 has a plurality of high lignin regions 352 dispersed in the low lignin region 351, so that it has a natural appearance and is excellent in menstrual blood concealment and antibacterial properties. And it has moderate bonding strength and liquid absorption between the core material covering sheet 322 and the surface sheet 311 .

In addition, the liquid-absorbent core material 321 may be formed only of SAP particles. In this case, the absorber 320 is comprised from the liquid-absorbent core material 321 which consists only of SAP particle|grains, and the core material covering sheet 322 which covers it. Although the low lignin region 351 of the covering sheet 322 by the core material has low liquid retention, the liquid-absorbent core 321 has a high liquid-absorbent capacity. Formed of SAP particles, the absorbent body 320 as a whole can exhibit moderate liquid absorbency.

The low lignin region 351 and the high lignin region 352 are formed by the bleached pulp fibers 341 and the unbleached pulp fibers 342 , therefore, the shape of the mutual boundary line is not clear, at least not a straight line but a wavy shape in a top view. Therefore, the required absorption area of the low lignin region 351 can be maintained per unit width (eg, 1.0 mm) near the boundary of the low lignin region 351 and the high lignin region 352 .

As shown again in FIG. 3 , in the central part of the absorber 320 in the lateral direction X, there is an overlapped part 323 in which both side edges 322a, 322b of the core covering sheet 322 are laminated together. The overlapping portion 323 is the folded portion of the core covering sheet 322. Therefore, compared with other portions of the absorbent body 320, the light brown color of the unbleached pulp fibers can be recognized deeper. From the perspective of appearance, as a line extending toward the longitudinal direction Y, Can be an accent part of the design. Also, the line extending in the longitudinal direction Y can be regarded as a mark showing the central portion of the absorber 320, and can be used for positioning when attaching the sanitary napkin 310 to underwear or the like. Also, even in the case where the liquid-absorbent core 321 absorbs a large amount of menstrual blood and the menstrual blood oozes from both ends thereof, since the overlapping portion 323 containing a large amount of hydrophobic high lignin region 352 is located between the longitudinal direction Y of the both end edges On the outside, menstrual blood can be effectively suppressed from oozing out from both side edge portions 320a and 320b of the absorber 320 .

The texture index of the core material covering sheet 322 is preferably 50-300. If the texture index of the core covering sheet 322 is less than 50, the pulp fibers will be densely and evenly arranged, resulting in a decrease in liquid permeability, and the menstrual blood cannot quickly migrate to the liquid-absorbent core 321 . In addition, if the organization index If it exceeds 300, extremely bad parts are formed, resulting in lowered tensile strength, and there is a possibility that a part may be broken during use.

<Measurement method of tissue index>

The texture index of the core covering sheet 322 was measured using a structure tester FMT-MIII manufactured by Nomura Corporation. The measurement area is 250mm×180mm, and the measurement time is 3 seconds/sample. The texture index on both surfaces of the surface of 3 samples is measured, and the average value is taken as the measurement value. The texture index means that the smaller the measured value, the less uneven texture.

Compared with the bleached pulp fiber 341, the rigidity of the unbleached pulp fiber 342 is higher, so when the core covering sheet is formed of only the unbleached pulp fiber 342, the softness becomes lower, and the action of the surface sheet 311 cannot be followed, and the There is a possibility that the core covering sheet is peeled off from the surface sheet 311, but since the high lignin region 352 is dispersed in the low lignin region 351, the flexibility is not greatly impaired.

Therefore, the core material covering sheet 322 has required flexibility, specifically, the wrinkle rate of the core material covering sheet 322 is 7-20%. When the wrinkle rate of the core material covering sheet 322 is less than 7%, the rigidity of the core material covering sheet 322 becomes high and cannot follow the action of the surface sheet 311. In addition, when the wrinkle rate exceeds 20%, the core material covering sheet The sheet 322 becomes too soft, and there is a possibility that the sheet may be damaged during manufacture or use.

<Measuring method of wrinkle ratio>

The wrinkle ratio of the core covering sheet 322 is measured by the underwater extensibility method Certainly. The core covering sheet 322 was cut into 100mm×100mm to prepare a measurement sample, and the measurement sample was immersed in water for 10 seconds and then pulled up, and the wrinkle rate was calculated from the dimensional change by the following formula. The measurement was performed three times (n=3), and the average value was used as the measured value.

Wrinkle rate (%)={(size after immersion in water)/(size before immersion in water)-1}×100

As the surface sheet 311, a hydrophilic sheet made of cotton fibers (including organic cotton) can be used. When this sheet is used as the surface sheet 311, it has excellent cushioning properties, skin touch properties, and liquid absorption properties. In addition, by forming the liquid-absorbing layer with the surface sheet 311 containing cotton fibers and the core material covering sheet 322 having the high lignin region 352, the core material covering sheet 322 has a small liquid retention property of the fibers. In addition, due to the surface The sheet has high hygroscopicity, so the surface sheet 311 can absorb moisture in the absorber 320 . Thereby, generation of moisture between the sanitary napkin and the body can be suppressed, and stuffiness inside can be suppressed.

However, it is preferable that the Klemm water absorption of the core covering sheet is higher than that of the surface sheet 311 containing cotton fibers. The Clem water absorption of the core material covering sheet 322 is higher than that of the surface sheet 311 on the side opposite to the skin, so that the menstrual blood absorbed and diffused on the surface sheet 311 can be covered with the core material. The cover sheet 322 is introduced to absorb and quickly move to the liquid-absorbent core material 321, which can effectively prevent the liquid remaining on the surface sheet 311.

[Determination method of Clem water absorption]

The measurement of the Cramer's water absorption of the core covering sheet 322 was performed in accordance with the Cramer's water absorption test (JIS-L1907, P8141). As a measuring tool, a ruler, a stopwatch, a plastic container, and artificial urine (colored with blue No. 1) were used. A sheet cut out from the core covering sheet 322 to a size of 25 mm in width and 150 mm in length was used as a sample (N=3). First, pour artificial urine into a plastic container until the depth of the artificial urine becomes 10mm or more. Next, the sampled test piece was fixed with a fixing jig, and it was attached so that it may be immersed in artificial urine to the depth of 5 mm from the front-end|tip of a sample. It was left in this state for 120 seconds (environment: temperature 20° C./humidity 60%). The artificial urine climbs along the sample, and the suction distance on the sample is measured from the surface of the artificial urine. The longer the absorption distance, the higher the water absorption of Clem.

Also, when using a sheet containing cotton fibers as the surface sheet, and using a thin paper mainly composed of bleached pulp fibers for the core covering sheet below it, the liquid retention is high, so menstrual blood cannot be quickly transferred to the surface. Absorbent core material. In this embodiment, since the core material covering sheet 322 has the high lignin region 352, the overall liquid retention property is lowered, and the menstrual blood can smoothly flow downward.

In addition, the surface sheet 311 may have a plural-layer structure, and in this case, it is preferable that the layer (upper layer) on the side facing the skin is substantially composed of cotton fibers. In this case, the cotton fibers can more efficiently absorb moisture in the portion close to the skin.

And, the surface sheet 311 has a multi-layer structure, located in the The layer (upper layer) on the skin-facing side is mainly formed of cotton fibers, and the layer (lower layer) on the non-skin-facing side is mainly formed of hydrophobic synthetic resin fibers. In this case, the Gramm water absorption of the surface sheet 311 becomes lower than that of the core covering sheet 322 regardless of the fact that the surface sheet 311 contains water-absorbent cotton fibers on the skin side. Since the Clem water absorption of the surface sheet 311 is lower than that of the core covering sheet 322, the surface of the sanitary napkin 310 does not spread bodily fluids and can be close to the absorber. The core covering sheet 322 of the absorbent body 320 diffuses the body fluid, and can suppress the body fluid absorbed by the absorbent body 320 from flowing back toward the surface side (Rewet back).

As mentioned above, the liquid-absorbent core material 321 may be selected from cellulose fibers such as cotton and pulp fibers, semi-synthetic cellulose fibers such as acetate, and regenerated cellulose fibers including rayon. Cellulose fibers etc. The core covering sheet 322, like the liquid-absorbent core 321, has cellulose fibers composed of bleached pulp fibers 341 and unbleached pulp fibers 342, so it has high affinity and is located between the contours of the absorbent body. When the core material covering sheet 322 and the liquid-absorbent core material 321 are welded to each other by pressing the grooves, etc., the joint strength can be improved.

The liquid-absorbent core material 321 may have a plurality of functional particles formed of activated carbon, zeolite, etc., and having an odor-adsorbing function of body fluid such as menstrual blood. The liquid-absorbent core material 321 has an odor absorbing property and complements the antibacterial property of the core material covering sheet 322, and the sanitary napkin 310 can be used and disposed of more hygienically and cleanly.

In this embodiment, to disperse in the low lignin area 351, the plurality of high-lignin regions 352 are located in the entirety of the core covering sheet 322, so not only the first covering part on the skin-facing side of the absorber 320 in the core covering sheet 322 is covered. 325 , a plurality of high lignin regions 352 are also dispersed in the second covering portion 326 on the non-skin-facing side of the covering absorbent body 320 . Therefore, in the cross-sectional view as shown in FIG. 3 , low lignin regions 351 and high lignin regions 352 alternately exist in the lateral direction X even in the second coating portion 326 .

Because the high-lignin region 352 has a higher bond strength to the sheet than the low-lignin region 351, it has an excellent bond to the back sheet 312 compared to the case of using a general core material that does not have the high-lignin region 352 to cover the sheet. The joint strength of the joint. Therefore, there is no need to increase the mass of the adhesive per unit area in order to increase the bonding strength, and there is no problem that the rigidity of the sheet increases and the followability to the absorber 320 decreases due to the increase of the adhesive.

(Second embodiment of the first invention)

Fig. 7 is a plan view of a sanitary napkin 310 according to a second embodiment of the first invention, and Fig. 8(a) is a cross-sectional view similar to Fig. 3 of the second embodiment. The basic structure of the sanitary napkin 310 of this embodiment is the same as that of the first embodiment, so only the differences will be described below.

In this embodiment, the sanitary napkin 310 has: a plurality of concave portions 360 that are concave in the liquid-absorbent layer 313 from the surface sheet 311 toward the back sheet 312; , a discontinuously extending press strip groove 370 in a circular shape. The concave portion 360 has a bottom, They are separated from each other in the longitudinal direction Y and the lateral direction X in a plan view. The concave portion 360 may have various well-known shapes such as a circle, an ellipse, a triangle, and a rectangle in addition to the illustrated one.

The concave portion 360 can be formed by, for example, pressurized heat treatment. Specifically, in conventional embossing, the absorber 320 and the top sheet 311 can be compressed by pressing an embossing pin from the top sheet 311 side. Therefore, in the absorber 320, the thin portion 361 in which the concave portion 360 exists has a higher fiber density than the thick portion 362 in which the concave portion 360 located in the periphery thereof does not exist. Since the core covering sheet 322 has a plurality of high lignin regions 352 , the diffusibility of body fluid is low, and there is a possibility that the body fluid cannot be diffused and absorbed throughout the liquid-absorbent core 321 .

In this embodiment, by having a plurality of concave portions 360 extending to the inside of the liquid-absorbent core material 321, bodily fluids can be directly retained in the concave portions 360, and the surface sheet 311 and the core material covering sheet 322 can be indirectly connected to the body fluid. The surface area of the liquid-absorbent core 321 in contact with the menstrual blood increases, and the liquid-absorbent core 321 can quickly absorb and hold menstrual blood through the two sheets 311 and 322 . Furthermore, since the thin portion 361 where the concave portion 360 exists has a higher fiber density than the thick portion 362, the bodily fluid accumulated in the concave portion 360 can be sucked downward more quickly to absorb and hold it.

Fig. 8(b) is a cross-sectional view similar to Fig. 8(a) of a modified example of the sanitary napkin 310 according to the second embodiment.

As shown in FIG. 8( b ), the concave portion 360 of this modified example is formed by an opening that penetrates the liquid-absorbing layer 313 in the thickness direction Z. As shown in FIG. On the bottom surface of the concave portion 360, there is a liquid-impermeable back sheet 312, therefore, it will not The body fluid accumulated in the through opening leaks to the outside, and can be absorbed and held by the absorber 320 from the peripheral wall of the opening.

(third embodiment of the first invention)

FIG. 9 shows an example of use of the absorbent article of the first invention. In this use example, the absorber 320 is used for a disposable diaper (absorbent article) 380 . The disposable diaper 380 shows a state in which the side seams of the side edges joining the front and rear waist sheets 384, 385 are peeled off and stretched horizontally and vertically.

The disposable diaper 380 has a front waist region 381 , a rear waist region 382 and a crotch region 383 between the front and rear waist regions 381 and 382 . In addition, the disposable diaper 380 is provided with: a front waist sheet 384 for partitioning the front waist region 381 and a part of the crotch region 383; a rear waist sheet 385 for partitioning the rear waist region 382 and a part of the crotch region 383; The liquid-absorbent structure 386 extending in the longitudinal direction on the skin-facing side of the waist sheets 384, 385 is arranged at intervals in the longitudinal direction in a state where both side edges of the front and rear waist sheets 384, 385 overlap each other. The plurality of seams are joined to each other and divided into a waist opening and a pair of foot openings. The absorber 320 is attached to the liquid-absorbent structure 386 and extends from the crotch region 383 toward the front and rear waist regions 381 and 382 .

The disposable diaper 380 is a so-called underpants type in which both side edges of the front and rear waist regions 381, 382 are joined in advance. Like the sanitary napkin 310, the absorbent body 320 is composed of a liquid-absorbent core material 321 and The core material covering sheet 322 covered by it is constituted, and the core material covering sheet 322 is composed of A peripheral region composed of the low lignin region 351 and a plurality of high lignin regions 352 scattered in the peripheral region. The light brown color of the core material covering sheet 322 can be seen through the absorbent body 320 from the inside view and/or the outside view of the disposable paper diaper 380, which can give the impression of a natural product using natural materials, and It has excellent antibacterial properties, and can quickly move body fluids such as urine and loose stools from the core covering sheet 322 to the liquid-absorbent core 321 . In addition, as an absorbent article of this invention, not only an underpants type paper diaper but also an open type paper diaper may be used.

In each embodiment, another sheet with high bulkiness and good cushioning properties may be disposed between the surface sheet 311 and the core covering sheet 322 . Since other sheets are bonded to the surface sheet 311, they can also be called a part of the surface sheet 311 substantially.

When the components constituting the absorbent articles 310 and 380 are not specifically described, in addition to the materials described in this specification, various known materials generally used in this field can be adopted without limitation. In addition, the terms "first", "second" and "third" used in this specification and claims are only for distinguishing the same elements, positions and the like.

(the second invention) (1st Embodiment of 2nd invention)

The following embodiments of the second invention relate to absorbent articles shown in the drawings, and include not only the indispensable configurations of the invention but also optional and desirable configurations. Hereinafter, referring to the drawings, the absorptivity of the present invention will be described. An embodiment of a sanitary napkin 410 as an example of an article. The sanitary napkin 410 has a vertical direction Y, a horizontal direction X, and a thickness direction Z.

As shown in Figures 10 to 12, the sanitary napkin 410 for sanitary use has a longitudinal centerline P that divides its widthwise dimension in half and a transverse centerline Q that divides its length dimension in half, and includes: the skin-facing surface (inner surface) 402 side and the non-skin-facing surface (outer surface) 403 side on the opposite side; convexly curved first and second end edges 410a, 410b; in the central part where the transverse centerline Q exists, a convex curve is formed The first and second side edges 410c, 410d; the liquid-permeable surface sheet 411 located on the skin-facing side; the liquid-impermeable back sheet 412 located on the non-skin-facing side; and the two sheets 411, Between 412 is a liquid-absorbent absorbent body 420 . The surface sheet 411 and the absorber 420 are bonded to each other by conventional bonding means such as hot-melt adhesive to form the liquid-absorbent layer 413 .

In addition, although not shown, in order to improve the softness of the sanitary napkin 410 , an intermediate sheet made of fiber nonwoven fabric with a high bulkiness may be arranged between the surface sheet 411 and the absorber 420 . In addition, between the absorber 420 and the back sheet 412, in order to suppress leakage of bodily fluids, a leak-proof sheet preferably made of air-permeable and liquid-impermeable nonwoven fabric or plastic film may be arranged.

The absorber 420 has: a first end edge 420a opposite to the first end edge 410a and a second end edge 420b opposite to the second end edge 410b; The first and second side edges 420c, 420d extending in the same direction. The front and back sheets 411, 412 extend outward from the outer periphery of the absorber 420, and on the skin-facing side of the surface sheet 411, a pair of sides extending in the longitudinal direction Y is disposed so as to face each other in the horizontal direction. Thin Sheet 414. The pair of side sheets 414 are bonded to the surface sheet 411 via side joints (not shown). Although not shown in the figure, in order to form a leak-proof wall rising toward the body side in the worn state, the elastic material extending in the longitudinal direction Y may be arranged so as to be contractible in the stretched state on the side sheet 414 . In addition, the side joint portion used to fix the side sheet 414 may also be a seal line extending in the longitudinal direction Y with design elements such as floral patterns and geometric patterns.

The sanitary napkin 410 is formed of a surface sheet 411, a back sheet 412, and a side sheet 414, and extends toward the lateral direction X outside the longitudinal direction Y of the first and second end edges 420a, 420b of the absorber 420. Both end portions 416 ; and both side edge portions 417 extending in the vertical direction Y on the outer side in the lateral direction X of the first and second side edges 420 c and 420 d of the absorber 420 . In the central portion of the sanitary napkin 410 in the longitudinal direction Y, there is a wing portion 418 convex outward in the lateral direction X and formed by a part of both side edge portions 417 . In addition, the sheets 411 , 412 , 414 laminated on each other are bonded to each other through the peripheral seal portion 419 existing along the outer peripheral edge of the sanitary napkin 410 .

As shown in FIG. 11 , a plurality of fixing regions 430 are arranged on the back side of the sanitary napkin 410 . A plurality of fixation areas 430 are used to fix the sanitary napkin 410 on garments such as underwear, and are formed by applying adhesives, pressure-sensitive adhesives, etc. in a plurality of lines extending in the longitudinal direction Y . The fastening region 430 has a central region 431 extending in the longitudinal direction Y in a region overlapping with the absorber 420 , and side regions 432 located in the flap portion 418 . The fixation area 430 is covered by a separator (not shown) made of plastic film.

The surface sheet 411 can be formed of various liquid-permeable fiber non-woven fabrics, such as air-through fiber non-woven fabrics with a mass of about 15-45 g/m ² , porous plastic films, or such laminated sheets. Also, the back sheet 412 may be formed of a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fiber non-woven fabric, or a laminated sheet thereof. The side sheet 414 can be made of the same sheet material as the surface sheet 411 . However, in order to effectively prevent lateral leakage of body fluids, it is better to use thin sheets with hydrophobic or water-repellent properties.

As the surface sheet 411, a sheet having unevenness on the surface side can also be used. The surface of the sheet is formed by a plurality of concave parts and a plurality of convex parts arranged alternately in the longitudinal direction Y or the lateral direction X. As a method of forming the plurality of convex parts and concave parts, for example, controlling the amount of fibers can be mentioned. A method of forming a portion with a low bulkiness and a portion with a high bulkiness, a method of forming a concave portion by embossing/debossing, a method of forming a concave-convex shape, and the like. The convex portion and the concave portion are arranged so that the fiber density is different from each other so that one is sparse and the other is dense. By joining the part (first part) where the fibers are sparsely arranged with the high-lignin region 452 of the core covering sheet 422 described later, the joint strength becomes higher. Part 2) joins the low lignin area 451 for higher liquid absorption.

Also, even if the menstrual blood is repeatedly excreted in a relatively short period of time, the menstrual blood can be temporarily collected in the concave portion to prevent menstrual blood from leaking laterally from the surface of the surface sheet 411 and between the surface sheet 411 and the core covering sheet 422. In addition, it is preferable that a part of the concave portion of the surface sheet 411 is substantially (continuously or discontinuously) surrounded by a press portion forming a press groove, a compressed concave portion formed by embossing, and the like. In this case, it is possible to suppress leakage of bodily fluid collected in the concave portion in the horizontal direction X and the vertical direction Y. and, on the surface When the surface of the sheet is concave-convex, the light brown core covering the sheet 422 is recognized to be darker in the concave portion than the convex portion from the surface viewing angle, so the decorative effect of color change will also be produced.

The peripheral sealing portion 419 can be joined by an adhesive, joined by known welding means such as ultrasonic welding, thermal welding, laser welding, and high-frequency welding, and joined by embossing. , or in combination. Also, the sheets 411 , 412 , and 414 stacked in the thickness direction Z are bonded to each other via an adhesive such as a hot-melt adhesive. As the coating method of the hot melt adhesive, for example, various known coating methods such as screw coating, coater coating, curtain coater coating, and spray coating can be mentioned.

As shown in FIGS. 12 and 13, the absorber 420 has a liquid-absorbent core material in which superabsorbent polymer particles (SAP) are mixed with cellulosic fibers such as fluff wood pulp and rayon fibers, and shaped into a predetermined shape. 421; and in order to improve its shape retention and liquid diffusivity, the liquid-permeable core material covering sheet 422 that covers the liquid-absorbent core material 421 as a whole.

The dimension of the core material covering sheet 422 in the longitudinal direction Y is larger than that of the liquid-absorbent core material in the longitudinal direction Y. The bottom surface side of the central part in the horizontal direction X of the core material 421 exists so that it may overlap with each other. By folding the side edges 422a and 422b together, an overlapping portion formed by stacking the side edges 422a and 422b extending in the longitudinal direction Y is formed in the central part of the absorber 420 in the transverse direction X. 423.

The core covering sheet 422 has: a first covering portion 425 covering the skin-facing side of the liquid-absorbent core 421; The second covering portion 426 on the non-skin-facing side of the body. In this embodiment, the core material covering sheet 422 is formed by one continuous sheet, but it is also possible to form the first core material covering sheet forming the first covering part 425 and the first core material covering sheet differently and The second core material covering sheet forming the second covering part 426 is constituted.

The core covering sheet 422 is formed of various known fiber non-woven fabrics or thin papers, mainly composed of pulp fibers. The pulp fibers of the core covering sheet 422 include: bleached pulp fibers subjected to lignin removal treatment; and unbleached pulp fibers not subjected to lignin removal treatment. Here, pulp fibers refer to non-wood pulp fibers containing cotton linters, Manila hemp, kenaf, rice straw, bamboo, and bananas as raw materials in addition to wood pulp fibers obtained from coniferous trees or hardwoods.

In addition, the core covering sheet 422 may have a first layer (upper layer or lower layer) composed of regenerated cellulose fibers such as rayon fibers, semi-synthetic cellulose fibers, etc. A multi-layer structure formed by the second layer (lower layer or upper layer) composed of lignin-removed unbleached pulp fibers 442. In this case, as will be described later, even if the second layer has a sea-island structure composed of low lignin regions 451 and high lignin regions 452 described later, in the first layer, the body fluid can be sufficiently diffused. The core material covers the entirety of the sheet 422 to produce diffuse patterns of bodily fluids. Thereby, even after bodily fluid has been absorbed multiple times, it is possible to suppress a decrease in bonding property with the surface sheet 411 and maintain good liquid absorbency.

Since the core covering sheet 422 has unbleached pulp fibers, it has a light brown (original color) from plant materials such as wood as a whole. Wood color). The sheets 411, 412, and 414 other than the core covering sheet are made white as a whole by kneading white pigments such as titanium dioxide into the constituent fibers. Therefore, the core covering sheet 422 is attached to the surface of the sanitary napkin 410 and/or Or from the rear view, it can be easily identified from other thin sheets 411 , 412 , 414 .

Pulp fibers are generally processed by adding tablets to the raw material chips and boiling under high temperature and pressure to digest the lignin after the raw material chip treatment process (the first stage of the lignin removal process), and the net to remove foreign matter in the pulp Board process, oxygen exposure process (second stage of lignin removal process) to decompose lignin remaining in the digestion process with oxygen, and bleaching process to bleach pulp using multiple chemicals to form bleached Bleached pulp fibers. Unbleached pulp fiber is the first stage of lignin removal treatment in each of these processes, and only undergoes a steaming process and a screen process, and a certain degree of lignin removal treatment is implemented.

The lignin content of the unbleached pulp fibers contained in the core covering sheet 422 is 0.2 to 10.0%.

The lignin content rate of unbleached pulp fiber can be measured as follows.

<Measuring method of lignin content> Quantification of ADF

Reagent: acidic detergent solution (dissolve 10g of hexadecyltrimethylammonium bromide in 500mL of 1N sulfuric acid); Acetone; as a defoamer, decahydronaphthalene (option).

<measurement sequence>

Weigh 300g of the sample, put it into a 50mL Erlenmeyer flask, and then add 30mL of acidic substance and solution. Then cover it with aluminum foil, put the Erlenmeyer flask into boiling water, and decompose for 60 minutes. After decomposition, move to a Gucci crucible covered with glass fiber filter paper (GA-200) for suction filtration, and wash the residue with hot water and acetone. After air-drying, heat-drying is carried out. In addition, after drying, the weight was weighed, and the weight minus the ash was used as ADF, but the ash after quantifying the lignin could not be used here.

lignin quantification

Reagent: 72% sulfuric acid

<measurement sequence>

Add a few drops of 72% sulfuric acid to the dried Gooch crucible to make the whole thing wet, then add sulfuric acid twice the amount of ADF, add sulfuric acid appropriately every hour, and let it stand for 3 to 4 hours. Then, perform suction filtration and wash with hot water until the furnace liquid does not become acidic. After air drying, it was heat dried and weighed. The Gooch crucible was ashed at 550°C to obtain the ash content.

The core covering sheet 422 has unbleached pulp fibers, so it is more suitable than using a core covering sheet composed only of bleached pulp fibers. In terms of the surface, it has a light brown color derived from plant materials, which can give the impression of a skin-friendly product using natural materials to the wearer or wearing aid. Also, since the core covering sheet 422 has a light brown color, when excreted menstrual blood passes through the surface sheet 411 and is absorbed and held by the absorbent body 420, redness of the menstrual blood can be suppressed. Thereby, it is possible to suppress the feeling of disgust of directly recognizing menstrual blood, and to alleviate the mental anxiety caused by recognizing the redness of menstrual blood, for example, for a wearer at the beginning of menstruation. In addition, since the lignin component has an antibacterial effect, the multiplication of miscellaneous bacteria after use can be suppressed, and it can be disposed of hygienically.

In order to make the core material covering sheet 422 exert the natural appearance, suppress menstrual blood redness and certain antibacterial effect, the lignin content of the core material covering sheet 422 is preferably 2-10%. When the lignin component content of the core material covering sheet 422 is less than 2%, the light brown color of the core material covering sheet 422 becomes so light that it cannot be visually distinguished from other white sheets 411, 412, 414. degree of risk. In addition, when the lignin component content rate of the core material covering sheet 422 exceeds 10%, the color of the lignin component becomes darker, which may damage the natural appearance of the natural material, and it becomes difficult to recognize the redness of menstrual blood. , there is a risk of not being able to correctly grasp the amount of menstrual blood.

As shown in FIGS. 12 and 13 , the liquid-absorbent layer 413 has: first and second end regions 413A, 413B facing each other in the longitudinal direction Y; and located between the first end region 413A and the second end region 413B. The middle region 413C. The liquid-absorbing layer 413 also has: from the surface sheet 411 toward the back sheet 412 side, a plurality of concave portions 460 that become concave; The way is to discontinuously extend the press bar groove 470 in a circular shape.

The press bar groove 470 has: the curved first contour groove 471 located in the first end region 413A; the curved second contour groove 472 located in the second end region 413B; the first contour groove 471 and the second contour Between the grooves 472, the third contour groove 473 located in the middle area 413C; the first inner contour groove 474 located in the first contour groove 471; and the second inner contour groove located in the second contour groove 472 Ditch 475.

The concave portion 460 has a bottom, extends continuously from the surface sheet 411 to a part of the liquid-absorbent core 421 , and is separated from each other in the longitudinal direction Y and the lateral direction X in plan view. The concave portion 460 has: the first concave portion 460a located in the area surrounded by the first and second inner contour grooves 474, 475 and the third outer contour groove 473; The second concave portion 460b in the region surrounded by the first inner contour groove 474; and the third concave portion 460c arranged in the region surrounded by the second outer contour groove 472 and the second inner contour groove 475 .

While the first concave portion 460a is substantially circular, the second and third concave portions 460b and 460c are different from the first concave portion 460a and have a substantially cross shape. The first concave portion 460a is arranged denser than the second and third concave portions 460b and 460c. The concave portion 460 may have various known shapes such as a circle, an ellipse, a triangle, and a rectangle in addition to the illustrated one. As various dimensions of the first concave portion 460a, for example, when it has a substantially circular shape, the diameter is 1.0 to 1.5 mm, the distance between X in the horizontal direction is 3.0 to 5.0 mm, and the distance between Y in the vertical direction is 5.0 to 7.0 mm. . Here, the pitch refers to the separation dimension between the center points of the first concave portions 460a.

By forming the plurality of concave portions 460 in the liquid-absorbent layer 413, curling, deformation, and the like of the absorbent body 420 during wearing can be suppressed. In particular, the region where the first concave portion 460a is arranged is opposed to the excretory opening of the wearer, and the absorber 420 is thicker than other regions. Therefore, by disposing the first concave portion 460a, can improve rigidity, and can effectively suppress curling, deformation, etc. during wearing. In addition, since the squeeze groove 470 extending circularly in the longitudinal direction Y is formed in the entire area of the absorber 420, bodily fluids can be quickly diffused through the squeeze groove 470, and the absorber 420 can be made to conform to the shape of the body. , deformed into a curved shape as a whole.

The concave portion 460 of the liquid-absorbing layer 413 can be formed, for example, by pressurized heat treatment. Specifically, the conventional embossing can be formed by pressing a heated embossing pin from the surface sheet 411 side of the liquid absorbing layer 413 to compress the absorber 420 together with the surface sheet 411 .

Generally, in addition to the shape retention of the liquid-absorbent core material, the core-covering sheet is ideally made of a hydrophilic sheet in order to have the function of absorbing and diffusing the body fluid passing through the surface sheet while migrating to the liquid-absorbent core material. The core material covering sheet 422 of this embodiment has a high content of unbleached pulp fiber-based lignin components, so it has a low degree of hydrophilicity and is hydrophobic, and cannot sufficiently absorb and retain menstrual blood passing through the surface sheet 411. It cannot migrate to the liquid-absorbent core material 421 quickly.

In this embodiment, by having a plurality of concave portions 460 extending to the inside of the liquid-absorbent core material 421, menstrual blood can be directly retained in the concave portions 460, and the surface sheet 411 and the core material covering sheet 422 can be indirectly connected to the menstrual blood. The surface area of the liquid-absorbent core material 421 contacted by the menstrual blood becomes larger, and the liquid-absorbent core 421 The material 421 can quickly absorb and retain body fluids through the two sheets 411 and 422 .

Since the core covering sheet 422 has unbleached pulp fibers, its diffusivity is lower than that of a core covering sheet formed of general tissue paper, so the menstrual blood entering the concave portion 460 will not spread and is kept in the Therefore, the bottom portion and the peripheral wall of the concave portion 460 can absorb bodily fluid in dots in the portion where the plurality of concave portions 460 are arranged. Therefore, it is possible to suppress the diffusion of bodily fluid to both side edges of the liquid-absorbent core 421 and the adhesion of menstrual blood to the body along the side sheet 414 .

In addition, at the bonding interface between the surface sheet 411 and the core covering sheet 422 via the hot-melt adhesive, the bleached pulp fibers absorb menstrual blood and swell, causing the bonding part to peel off and reduce the bonding strength. The unbleached pulp fiber is less hydrophilic than the bleached pulp fiber 441 and is hydrophobic, so it is not easy to absorb menstrual blood and swell, and the joint part will not peel off. Therefore, the core covering sheet 422 is mixed with bleached pulp fibers and unbleached pulp fibers, so that peeling, floating, etc. of the surface sheet 411 during wearing can be suppressed. In addition, if the amount of adhesive is increased in order to increase the joint strength of the two sheets 411, 422, although there is a possibility that the rigidity of the sheet will increase and the flexibility and liquid permeability will decrease, but by adjusting the content of unbleached pulp fibers, This disadvantage does not arise, and joint strength can be controlled.

The second covering portion 426 of the core covering sheet 422 is bonded to the back sheet 412 via a hot-melt adhesive. Since the core covering sheet 422 contains unbleached pulp fibers, compared with the core covering sheet composed only of bleached pulp fibers, the back sheet 412 and the core covering sheet The bonding interface of 422 bonded by hot melt adhesive is not easy to peel off and has the required bonding strength. Therefore, there is no need to improve the quality of the hot-melt adhesive to prevent the peeling of the sheet, and there is no problem that the rigidity of the sheet increases and the followability to the absorber 420 decreases due to the improvement in the quality of the hot-melt adhesive.

The first covering part 425 and the surface sheet 411 of the core covering sheet 422, and the second covering part 426 and the back sheet 412 are preferably bonded to each other via rubber-based adhesives such as SIS-based hot-melt adhesives. Since the sheets 411 , 412 , 422 are bonded to each other through SIS adhesives, compared with EVA resin adhesives using organic solvents, the volatile organic compound (VOC) value can be reduced, making it more skin-friendly and safe to use.

Therefore, the thin portion (the bottom of the concave portion 460 ) 461 in the absorber 420 where the concave portion 460 exists has a higher density than the thick portion 462 without the concave portion 460 located around it. Since the density of the thin-walled portion 461 in the concave-shaped portion 460 becomes higher, the menstrual blood entering the concave-shaped portion 460 can be absorbed and diffused more rapidly through the thin-walled portion 461 .

The texture index of the core covering sheet 422 is preferably 50-300. If the texture index of the core covering sheet 422 is less than 50, the pulp fibers will be densely and uniformly arranged, resulting in a decrease in liquid permeability, and the menstrual blood cannot quickly migrate to the liquid-absorbent core 421 . In addition, when the texture index exceeds 300, extremely poor textured parts are formed, resulting in reduced tensile strength, and there is a possibility that a part may be broken during use.

<Measurement method of tissue index>

The texture index of the core covering sheet 422 was measured using a structure tester FMT-MIII manufactured by Nomura Corporation. The measurement area is 250mm×180mm, and the measurement time is 3 seconds/sample. The texture index on both surfaces of the surface of 3 samples is measured, and the average value is taken as the measurement value. The texture index means that the smaller the measured value, the less uneven texture.

Compared with bleached pulp fibers, unbleached pulp fibers have higher rigidity, so when the core covering sheet 422 is formed of only unbleached pulp fibers, the softness becomes lower, and it is impossible to follow the movement of the surface sheet 411. There is a possibility that the core covering sheet is peeled off from the surface sheet 411, but since bleached pulp fibers are also included, the softness is not greatly impaired. Therefore, the core material covering sheet 422 has required flexibility, specifically, the wrinkle ratio of the core material covering sheet 422 is 7 to 20%. When the wrinkle rate of the core material covering sheet 422 is less than 7%, the rigidity of the core material covering sheet 422 becomes high and cannot follow the movement of the surface sheet 411 . In addition, when the wrinkle rate exceeds 20%, the core covering sheet 422 becomes too soft, and there is a possibility that the sheet may be damaged during manufacture or use.

<Measuring method of wrinkle ratio>

The wrinkle rate of the core covering sheet 422 is measured by the underwater extensibility method. The core covering sheet 422 was cut into 100mm×100mm to prepare a measurement sample, and the measurement sample was immersed in water for 10 seconds and then pulled up, and the wrinkle rate was calculated from the dimensional change by the following formula. The measurement was performed three times (n=3), and the average value was used as the measured value.

Wrinkle rate (%)={(size after immersion in water)/(size before immersion in water)-1}×100

As the surface sheet 411, a hydrophilic sheet made of cotton fibers (including organic cotton) can be used. When this sheet is used as the surface sheet 411, it has excellent cushioning properties, skin touch properties, and liquid absorption properties. Also, by forming the liquid-absorbing layer with the surface sheet 411 containing cotton fibers and the core material covering sheet 422 having the high lignin region 452, the core material covering sheet 422 has a low liquid retention property of the fibers. In addition, due to the surface The sheet has high hygroscopicity, so the surface sheet 411 can absorb moisture in the absorber 420 . Thereby, generation of moisture between the sanitary napkin and the body can be suppressed, and stuffiness inside can be suppressed.

The Klemm water absorption of the core covering sheet 422 is preferably higher than that of the surface sheet 411 containing cotton fibers. The Clem water absorption of the core material covering sheet 422 is higher than that of the surface sheet 411 on the side opposite to the skin, so that the menstrual blood absorbed and diffused on the surface sheet 411 can be covered with the core material. The cover sheet 422 is introduced to absorb and quickly move to the liquid-absorbent core material 421, which can effectively prevent the liquid remaining on the surface sheet 411.

[Determination method of Clem water absorption]

The measurement of the Cramer's water absorption of the core covering sheet 422 was performed in accordance with the Cramer's water absorption test (JIS-L1907, P8141). As a measuring instrument, use a ruler, a stopwatch, a plastic container, and artificial urine (marked in cyan l size) color). A sheet cut out from the core covering sheet 422 to a size of 25 mm in width and 150 mm in length was used as a sample (N=3). First, pour artificial urine into a plastic container until the depth of the artificial urine becomes 10mm or more. Next, the sampled test piece was fixed with a fixing jig, and it was attached so that it may be immersed in artificial urine to the depth of 5 mm from the front-end|tip of a sample. It was left in this state for 120 seconds (environment: temperature 20° C./humidity 60%). The artificial urine climbs along the sample, and the suction distance on the sample is measured from the surface of the artificial urine. The longer the absorption distance, the higher the water absorption of Clem.

In addition, the surface sheet 411 may have a multi-layer structure, and in this case, it is preferable that the layer (upper layer) on the side facing the skin is substantially composed of cotton fibers. In this case, the cotton fibers can more efficiently absorb moisture in the portion close to the skin.

And, the surface sheet 411 has a multi-layer structure, the layer (upper layer) positioned on the skin-facing side is mainly formed of cotton fibers, and the layer (lower layer) positioned on the non-skin-facing side is mainly made of hydrophobic synthetic resin fibers. formed. In this case, the Gramm water absorption of the surface sheet 411 becomes lower than that of the core covering sheet 422 regardless of the fact that the surface sheet 411 contains water-absorbent cotton fibers on the skin side. Since the Gramm water absorption of the surface sheet 411 is lower than that of the core covering sheet 422, the surface of the sanitary napkin 410 does not spread bodily fluids and can be close to the absorber. The core covering sheet 422 of the absorbent body 420 diffuses the body fluid and can suppress the body fluid absorbed by the absorbent body 420 from rewetting back toward the surface side.

The liquid-absorbent core material 421 is as mentioned above, as an option, except In addition to cellulose fibers such as cotton and pulp fibers, semi-synthetic cellulose fibers such as acetate, cellulose-based fibers including regenerated cellulose fibers such as rayon, etc. may be used. The core material covering sheet 422 is also similar to the liquid-absorbent core material 421, since it has cellulose fibers composed of bleached pulp fibers and unbleached pulp fibers, it has high affinity, and the core material is placed in the press groove 470. When the cover sheet 422 and the liquid-absorbent core material 421 are welded to each other, the bonding strength can be improved.

In addition, the liquid-absorbent core material 421 may be formed only of SAP particles. In this case, the absorber 420 is comprised from the liquid-absorbent core material 421 which consists only of SAP particle|grains, and the core material covering sheet 422 which covers it. In this case, since the core covering sheet 422 has the low-lignin region 451 described later, the liquid retention is low, but the liquid-absorbent core 421 is formed of SAP particles having a high liquid-absorbing capacity, absorbing The body 420 as a whole can exhibit moderate liquid absorbency.

The liquid-absorbent core material 421 may have a plurality of functional particles formed of activated carbon, zeolite, etc., and having an odor-absorbing function of body fluid such as menstrual blood. The liquid-absorbent core material 421 has an odor absorbing property, which complements the antibacterial property of the core material covering sheet 422, and the sanitary napkin 410 can be used and disposed of more hygienically and cleanly.

As shown again in FIGS. 12 and 13 , in the central portion of the absorber 420 in the lateral direction X, there is an overlapping portion 423 in which both side edges 422a, 422b of the core covering sheet 422 are laminated together. The overlapping portion 423 is the portion where the core covering sheet 422 is folded, so that the light brown color of the unbleached pulp fibers can be recognized more deeply than the rest of the absorbent body 420, in The appearance perspective, as a line extending in the longitudinal direction Y, can become an emphasized part of the design. Also, the line extending in the longitudinal direction Y can be regarded as a mark showing the central portion of the absorber 420 and used for positioning when attaching the sanitary napkin 410 to underwear or the like. Also, even in the case where the liquid-absorbent core 421 absorbs a large amount of menstrual blood and the menstrual blood oozes from both ends thereof, since the overlapping portion 423 containing a large amount of hydrophobic unbleached pulp fibers is positioned between the longitudinal direction Y of the both end edges On the outside, menstrual blood can be effectively suppressed from oozing out from both side edge portions 420c and 420d of the absorber 420 .

Fig. 14 is a cross-sectional view similar to Fig. 13 of an example of modification 420 of the absorber. In this modified example, the plurality of concave portions 460 formed in the liquid-absorbing layer 413 are formed by openings penetrating the surface sheet 411 and the absorber 420 . The opening can be formed by hollowing out the entire thickness dimension of the liquid absorbing layer 413 . There is a liquid-impermeable back sheet 412 on the bottom surface of the concave portion 460, so that the body fluid collected on the body surface does not leak out, and can be absorbed and held by the absorbent body 20 from the peripheral wall of the opening.

(Second embodiment of the second invention)

Fig. 15 is a plan view of the absorber 420 of the sanitary napkin 410 of the second embodiment of the second invention, Fig. 16 is a partially enlarged view of the area surrounded by line XVI in Fig. 15, and Fig. 17 is the sanitary napkin of the second embodiment The same sectional view of the sanitary napkin as in Fig. 13 .

In this embodiment, the first covering part 425 of the core material covering sheet 422 has: a low lignin region (low lignin content region) 451 in which the content of the lignin component is low; The high lignin region (high lignin content region) 452 is high in the region 451 . The low lignin region 451 is mainly formed by aggregating bleached pulp fibers 441 , and the high lignin region 452 is formed mainly by aggregating unbleached pulp fibers 442 . In the plan view of the first coating portion 425 of the core covering sheet 422, the low lignin region 451 is a peripheral region located in a wide range of the outer surface of the core covering sheet 422, while the high lignin region 452 is arranged. Pairs of low lignin regions 451 exist scattered. In addition, due to this arrangement, the first covering portion 425 of the core covering sheet 422 can be said to have a sea-island structure with the low lignin region 451 as the sea and the high lignin region 452 as the island.

The core covering sheet 422 of this embodiment is formed into a thin sheet by entangling a mixture of bleached pulp fibers 441 and unbleached pulp fibers 442 during the papermaking process. The low lignin region 451 is mainly composed of bleached pulp fibers 441, high wood The quality area 452 is mainly equipped with unbleached pulp fibers 442, therefore, the boundary between the two areas 451 and 452 is not clear and cannot be clearly distinguished. In addition, in this way, as a method of forming the core material covering the entire outer surface of the sheet 422 so that the high lignin regions 452 are dispersed in the low lignin region 451, for example, the mixing method and mixing ratio of the pulp fibers 441 and 442 can be appropriately adjusted. , the transport speed of the transport conveyor during production, the nozzle diameter when the pulp fiber 440 is deposited on the conveyor through the air injected from a plurality of nozzles, the air volume and wind speed of the blown air, and the like.

Since the two regions 451 and 452 are formed by adjusting various conditions in the manufacturing process, it can also be said that a part of the low lignin region 451 contains unbleached pulp fibers 442 and a part of the high lignin region 452 contains Bleached pulp fibers 441. Therefore, the low lignin region 451 and the high lignin region 452 are not only the bleached pulp fibers 441 and the unbleached pulp fibers 442 respectively, but also contain other fibers other than pulp fibers, for example, the pulp in the low lignin region 451 The content rate of the bleached pulp fiber 441 in the fiber is 50-100%, and the content rate of the unbleached pulp fiber 442 in the pulp fiber in the high lignin region 452 is 50-100%.

Since the high lignin region 452 refers to a region with a higher lignin content than the low lignin region 451 in the peripheral region of the core covering sheet 422 , the bleached pulp fiber 441 and the unbleached pulp fiber 442 may not be used to form it. For example, the high lignin region 452 in which the lignin content is higher than the surrounding region is formed by sporadically infiltrating a lignin component-containing liquid into a fibrous nonwoven fabric sheet formed of rayon fiber, synthetic fiber, or the like.

As shown in FIG. 17 , since the first coating portion 425 of the core material covering sheet 422 has a low lignin region 451 and a plurality of high lignin regions 452 scattered around it, the two regions 451, The 452 lines are interactively presented in the horizontal direction X. The high lignin regions 452 are scattered and arranged in the low lignin region 451 , so not only in the horizontal direction X, but also in the vertical direction Y, the low lignin regions 451 and the high lignin regions 452 are alternately arranged.

In this way, in the cross-sectional view of the first covering part 425, the low lignin region 451 and the high lignin region 452 are alternately located in the horizontal direction X and the vertical direction Y, so that the menstrual blood that has passed through the surface sheet 411 can be sucked into the hydrophilic surface. The low lignin region 451 quickly migrates to the liquid-absorbent core 421 and absorbs and retains it with a desired absorption speed.

The low lignin region 451 and the high lignin region 452 are formed by the bleached pulp fibers 441 and the unbleached pulp fibers 442, therefore, the shape of the mutual boundary line is not clear, at least it is not a straight line but has a serpentine shape in the top view. wavy. Therefore, a desired absorption area can be maintained per unit width (for example, 1.0 mm) near the boundary between the low lignin region 451 and the high lignin region 452 .

(third embodiment of the second invention)

FIG. 18 is a plan view showing an absorbent article according to a third embodiment of the second invention, and the absorbent body 420 is used for a disposable diaper (absorbent article) 480 . The disposable diaper 480 shows a state in which the side seams of the side edges joining the front and rear waist sheets 484, 485 are peeled off and stretched in the horizontal and vertical directions.

The disposable diaper 480 has a front waist region 481 , a rear waist region 482 and a crotch region 483 between the front and rear waist regions 481 and 482 . In addition, the disposable diaper 480 is provided with: a front waist sheet 484 for partitioning the front waist region 481 and a part of the crotch region 483; a rear waist sheet 485 for partitioning the rear waist region 482 and a part of the crotch region 483; The liquid-absorbent structure 486 extending in the longitudinal direction on the skin-facing side of 485 is formed by a plurality of seams arranged at intervals in the longitudinal direction in a state where both side edges of the front and rear waist sheets 484, 485 overlap each other. The waist, joined to each other, is divided into a waist opening and a pair of foot openings. The absorber 420 is attached to the liquid-absorbent structure 486 and extends from the crotch region 483 toward the front and rear waist regions 481 and 482 .

The disposable diaper 480 is a so-called underpants type in which both side edges of the front and rear waist regions 481, 482 are joined in advance. Like the sanitary napkin 410, the absorbent body 420 is composed of a liquid-absorbent core material 421 and a core covering it. The core covering sheet 422 is composed of unbleached pulp fibers 442 , and a plurality of concave portions 460 are formed in the liquid-absorbing layer 413 . The light brown color of the core covering sheet 422 can be seen through the absorbent body 420 from the inside view and/or the outside view of the disposable diaper 480, which can give a natural product impression using natural materials and has excellent antibacterial properties , bodily fluids such as urine and loose stools can quickly move from the core covering sheet 422 to the liquid-absorbent core 421 through the plurality of concave portions 460 . In addition, as an absorbent article of this invention, not only an underpants type paper diaper but also an open type paper diaper may be used.

In each embodiment, another sheet with high bulkiness and good cushioning properties may be disposed between the surface sheet 411 and the core covering sheet 422 . Since other sheets are bonded to the surface sheet 411, they can also be called a part of the surface sheet 411 substantially.

When the components constituting the absorbent articles 410 and 480 are not particularly clearly described, various known materials generally used in this field can be adopted without limitation in addition to the materials described in this specification. In addition, the terms "first" and "second" used in this specification and claims are only for distinguishing the same elements, positions, and the like.

311: surface flakes

312: back sheet

314: side sheet

320: absorber

320c: 1st side edge

320d: 2nd side edge

321: Absorbent core material

322: core material covering sheet

322a, 322b: both side edges

323: Overlap

325: 1st Covering Department

326: The second covered part

331: central area

351: low lignin area

352: high lignin area

Claims (20)

An absorbent article comprising a liquid-permeable top sheet on a skin-facing side; a liquid-impermeable back sheet on a non-skin-facing side; and an absorbent body positioned between the top sheet and the back sheet, It is characterized in that: the aforementioned absorbent system has a liquid-absorbent core material; and a core material covering sheet covering at least the skin-facing side of the aforementioned liquid-absorbent core material, and the aforementioned core material covering sheet is tied to cover the aforementioned liquid-absorbent core. The first covering portion on the skin-facing side of the core material has a plurality of high lignin regions that have a higher lignin content than the surrounding area and are dispersed in a plan view. The core material covers one of the lignin components of the sheet. The content rate is 0.2 to 10%, and the content rate of the lignin component of the aforementioned core material covering sheet is higher than the content rate of the lignin component of the aforementioned liquid-absorbent core material. For example, the absorbent article of claim 1, wherein the wrinkle rate of the aforementioned core material covering sheet is 7 to 20%, and the tissue index is 50-300. The absorbent article according to claim 1 or 2, wherein the core covering sheet contains wood or non-wood pulp fibers, and the liquid-absorbent core contains cellulose fibers. The absorbent article according to claim 1 or 2 of the patent claims, wherein the liquid-absorbent core material contains particles having odor-absorbing properties. The absorbent article according to claim 1 or 2, wherein the absorbent system has a plurality of concave portions that are concave from the skin-facing side toward the non-skin-facing side. The absorbent article according to Claim 1 or 2, wherein the core covering sheet further has a second covering portion covering the non-skin-facing side of the liquid-absorbent core, and a plurality of the high lignin regions Located in the aforementioned 2nd covered part. The absorbent article as claimed in claim 1 or 2, wherein the surface sheet contains cotton fibers, and the Klemm water absorption of the core covering sheet is higher than the Klemm water absorption of the surface sheet . The absorbent article according to claim 1 or 2 of the patent claims, wherein the surface sheet has a first part and a second part having a denser fiber density than the first part, and the first part is joined to the high lignin region , the aforementioned second portion is joined to the aforementioned low lignin area located in the aforementioned peripheral area. For example, the absorbent article of Claim 7 of the patent application, wherein the above-mentioned surface sheet has a multi-layer structure, and the layer on the side facing the skin is mainly Made of cotton fibers. The absorbent article according to claim 9, wherein the Gramm water absorption of the surface sheet is lower than that of the core covering sheet. An absorbent article having a thickness direction and comprising a liquid-permeable top sheet on a skin-facing side; a liquid-impermeable back sheet on a non-skin-facing side; and a liquid-impermeable back sheet positioned between the front sheet and the back sheet The absorbent body in between is characterized in that: the above-mentioned absorbent system has a liquid-absorbent core material; The first covering part on the skin-facing side of the liquid-absorbent core, the first covering part and the surface sheet are bonded to each other via an adhesive, and the core covering sheet and the liquid-absorbent core each contain pulp Fibers, the content of the lignin component of the core material covering sheet by the aforementioned pulp fiber is higher than the content of the lignin component of the aforementioned liquid-absorbent core material by the aforementioned pulp fiber, and the content of the aforementioned core material covering sheet The content rate of lignin component is 0.2 to 10%, and in the aforementioned thickness direction, there is at least continuous from the aforementioned surface sheet A plurality of recesses extending to a part of the aforementioned liquid-absorbent core material. The absorbent article according to claim 11, wherein the core covering sheet further has a second covering portion covering the non-skin-facing surface side of the liquid-absorbent core, and the second covering portion is connected to the back surface. The sheets are bonded to each other via an adhesive. The absorbent article according to claim 11 or 12, wherein the concave portion is a bottomed concave portion, and part of the surface sheet, the core covering sheet and the liquid-absorbent core are compressed, The thin portion where the concave portion exists has a higher density than the thick portion where the concave portion does not exist. The absorbent article according to claim 11 or 12 of the patent claims, wherein the concave portion is an opening through which the surface sheet and the absorber pass through in the thickness direction. Such as the absorbent article of claim 11 or 12, wherein the aforementioned adhesive is a SIS-based hot-melt adhesive. The absorbent article according to claim 11 or 12, wherein the core covering sheet has a plurality of high lignin regions that have a higher lignin component content than the surrounding region and are dispersed in a plan view. Such as the absorbent article of claim 11 or 12, wherein the wrinkle rate of the aforementioned core covering sheet is 7 to 20%, and the texture index is 50-300. The absorbent article according to claim 16, wherein the surface sheet has a first part and a second part having a denser fiber density than the first part, the first part is joined to the high lignin region, and The second part is joined to the aforementioned peripheral area. The absorbent article as claimed in claim 11 or 12, wherein the above-mentioned surface sheet has a multi-layer structure, and the layer on the side facing the skin is mainly composed of cotton fibers. The absorbent article according to claim 19, wherein the Gramm water absorption of the surface sheet is lower than that of the core covering sheet.

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