JP5973156B2 - Absorbent articles - Google Patents

Description

  The present invention relates to an absorbent article such as a disposable diaper.

  As an absorbent article such as a disposable diaper, a liquid-permeable surface sheet that forms a skin-facing surface, a liquid-impermeable back sheet that forms a non-skin-facing surface, and an absorbent body disposed between these sheets are provided. Things are known. Moreover, what is comprised as an absorber including the absorptive core containing hydrophilic fibers, such as wood pulp, and / or a water absorbing polymer, and the core wrap sheet which coat | covers this absorptive core is known. .

  Further, regarding the surface sheet, a technique is known in which an uneven structure is imparted to the surface sheet to suppress the flow and diffusion in the surface direction of excretory fluid such as urine and loose stool, particularly relatively high-viscosity excretory fluid such as soft stool Yes. For example, Patent Document 1 has an upper layer directed to the wearer's skin side and a lower layer disposed on the absorber side, and the upper layer and the lower layer are partially joined to form a large number of joints. There is described a surface sheet in which the upper layer protrudes toward the wearer's skin side at a portion other than the joint portion, and forms a plurality of convex portions that are hollow inside. Further, in Patent Document 2, a flow inhibiting member (for example, a concavo-convex sheet) having a low flow rate of pseudo-soft stool is attached to a part of the skin-facing surface of the surface sheet as compared with other parts of the skin-facing surface. Is described.

  Moreover, regarding the absorbent core, Patent Document 3 discloses that the absorbent core (absorbent pad) has an absorbent core in the front region in the longitudinal direction of the absorbent core for the purpose of improving the fit of the absorbent article (absorbent pad) to the wearer's body. It is described that a pair of flexible shafts extending in the longitudinal direction of the core, specifically, through-holes penetrating the absorbent core in the thickness direction are formed. According to Patent Document 3, since the pair of flexible shafts are exclusively located in the front region of the absorbent core sandwiched between the wearer's crotch, pressure from the lateral direction is applied to the absorbent core during wearing. Even if added, the front area deforms along the flexible axis without being twisted inappropriately to fit the wearer's body, while the rear area does not deform as much as in the front area. It is said that the absorbent pad can cover the wearer's body leaving a room. The through-hole (flexible shaft) described in Patent Document 3 is mainly for controlling the deformation of the absorbent core at the time of wearing to improve the fit to the wearer's body. Does not describe the control of excretory fluid through the through-holes.

Regarding the core wrap sheet, Patent Document 4 describes that the diffusion rate of the core wrap sheet (crepe paper) is made larger than that of the absorbent core (absorbent body). According to Patent Document 4, by setting the diffusion rate in this way, the diffusion rate gradient becomes an inclined gradient from the top sheet to the absorbent core, whereby the body fluid discharged to the top sheet becomes an intermediate core. It is said that the wrap sheet does not significantly inhibit the body fluid, and the body fluid is quickly absorbed by the absorbent core, thereby preventing the body fluid from leaking. Patent Document 4 describes that the diffusion rate of crepe paper is 0.5 cm ³ / second or more, and this diffusion rate is obtained by stacking 10 sheets to be measured (crepe paper) as a measurement sample. And dropping the measurement sample into a petri dish containing horse blood, measuring the time (diffusion time) for the measurement object sheet to absorb horse blood, and dividing the volume of the measurement sample by the diffusion time. Is calculated by

JP 2004-174234 A JP 2009-136311 A JP 2006-149571 A JP 2005-566 A

  In the disposable diaper, there is a problem that the excretion liquid such as urine and feces adheres to the skin of the wearer during wearing, so that the skin becomes red or rash. Such a rough skin of the wearer has a stronger irritation to the skin, firstly, a relatively low-viscosity excretory liquid such as urine adheres to the skin, thereby causing the skin to swell and be easily damaged. In many cases, it is caused by the attachment of stool such as loose stool. To solve the problem of rough skin, the absorption of urine and loose stool is increased, so-called wet back (excretion fluid that has passed through the top sheet is retained in the absorber). It is necessary to reduce the phenomenon of returning to the top sheet without being attached to the skin. Patent Documents 1 to 4 do not particularly describe the problem of rough skin of the wearer caused by such urine and stool, and adhere excrement fluid such as urine and loose stool to the wearer's skin in the absorbent article. The technology to make it difficult has not been established yet.

  Therefore, the subject of this invention is providing the absorbent article which is excellent in the absorbability of excretion liquids, such as urine and a loose stool, and an excretion liquid cannot adhere to a wearer's skin easily.

The present invention comprises an absorbent body and a surface sheet disposed on the skin-facing surface side of the absorbent body, and the absorbent body covers the absorbent core and at least the skin-facing surface of the absorbent core; The surface sheet has a large number of convex portions protruding toward the wearer's skin side, and the absorbent core includes at least the absorbent core. A slit having an opening on the non-skin facing surface side is formed to extend in a predetermined direction, and the portion of the core wrap sheet that covers the skin facing surface of the absorbent core is a low viscosity measured by the following method The problem is solved by providing an absorbent article having a liquid permeation time of 2.5 seconds or less.
<Measurement method of liquid permeation time of low viscosity liquid>
Two cylinders with an inner diameter of 35 mm that open at the top and bottom are placed one above the other with the axes of both cylinders aligned, and the measurement target sheet (core wrap sheet) is sandwiched between the upper and lower cylinders. 40 g ± 1 g of physiological saline is supplied into the cylinder. The physiological saline is supplied into the upper cylinder by injecting the physiological saline into the upper cylinder all at once from a container containing 40 g ± 1 g of physiological saline. The supplied physiological saline passes through the measurement target sheet or is absorbed by the measurement target sheet and disappears from the upper cylinder. The time from the start of the supply of the physiological saline to the time when the surface of the physiological saline reaches the same position as the surface of the measurement target sheet is measured, and the time is defined as the liquid permeation time.

  ADVANTAGE OF THE INVENTION According to this invention, the absorptive article which is excellent in the absorbability of excretion liquids, such as urine and a loose stool, and excrement liquid cannot adhere to a wearer's skin is provided.

FIG. 1 is a view showing an example of a disposable diaper as an embodiment of the absorbent article of the present invention, and is a skin-facing surface side (surface sheet side) showing a state in which the elastic member of each part is expanded and expanded in a flat shape Is a schematic plan view of FIG. 2 is a schematic cross-sectional view showing a cross section taken along the line II (cross section in the width direction) of FIG. FIG. 3 is a schematic perspective view showing a part of the surface sheet in the disposable diaper shown in FIG. 1 in an enlarged manner. 4 (a) and 4 (b) are diagrams each schematically showing an arrangement pattern of recesses (joining portions) in the topsheet according to the present invention. FIG. 5 is an explanatory diagram of a method for measuring the liquid permeation time. FIG. 6 is a schematic cross-sectional view showing a cross-section in the width direction of another embodiment of the absorbent body according to the present invention.

  Hereinafter, the absorbent article of the present invention will be described based on a disposable diaper which is a preferred embodiment thereof with reference to the drawings. The diaper 1 of this embodiment is equipped with the surface sheet 2 distribute | arranged to the skin opposing surface side of the absorber 4 and the absorber 4, as shown in FIG.1 and FIG.2, and the absorber 4 is the absorptive core 40. FIG. And a core wrap sheet 41 that covers at least the skin facing surface 40a of the absorbent core 40.

  More specifically, the diaper 1 of the present embodiment is a so-called unfolded disposable diaper. As shown in FIGS. 1 and 2, a liquid-permeable surface sheet 2 that forms a skin facing surface, a non-skin facing surface, A liquid-impermeable or water-repellent (hereinafter collectively referred to as “liquid-impermeable”) back sheet 3 to be formed, and a liquid-retaining absorbent 4 disposed between both sheets 2 and 3, It is formed vertically. Each of the top sheet 2, the back sheet 3, and the absorber 4 has a vertically long shape that is long in one direction X. Each of the top sheet 2 and the back sheet 3 has a size larger than that of the absorber 4, and extends outward from the peripheral edge of the absorber 4. As shown in FIG. 2, the width of the top sheet 2 in the width direction Y is smaller than the width of the back sheet 3 in the width direction Y.

  As shown in FIG. 1, the diaper 1 has, in the longitudinal direction X, a back side portion A disposed on the back side of the wearer at the time of wearing, and a ventral side portion B disposed on the abdomen side of the wearer at the time of wearing, And a crotch part C on which the wearer's crotch is arranged when worn. The crotch part C includes an excretion part facing part that is disposed so as to face the wearer's excretion part when worn, and is located at the central part in the longitudinal direction X of the diaper 1. The diaper 1 has an hourglass shape in which both side edges of the crotch part C are curved in an inward arc shape, and the center part in the longitudinal direction X is inwardly bounded in a plan view as shown in FIG. Yes.

  In the present specification, the skin facing surface is a surface of the absorbent article (disposable diaper) or a component thereof (for example, the absorbent core 40) that is directed toward the wearer's skin when the absorbent article is worn, The facing surface is a surface of the absorbent article or its constituent member that is directed to the side opposite to the skin side (clothing side) when the absorbent article is worn. Moreover, a longitudinal direction is a direction along the long side of an absorbent article or its structural member, and a width direction is a direction orthogonal to this longitudinal direction. In the figure, the direction indicated by the symbol X is the longitudinal direction of the diaper 1 (absorbent core 40), and the direction indicated by the symbol Y is the width direction of the diaper 1 (absorbent core 40).

  The liquid-retaining absorbent core 40 constituting the absorbent body 4 has both side edges of the crotch portion C curved inwardly in an arcuate shape, and in the plan view as shown in FIG. It has an hourglass shape that is bound inward. Moreover, the core wrap sheet | seat 41 which comprises the absorber 4 is one continuous sheet | seat, and covers the whole skin opposing surface 40a of the absorptive core 40, as shown in FIG. Is extended outward from both side edges along the longitudinal direction X in the width direction Y, and the extended portion is wound down below the absorbent core 40 to cover the entire non-skin facing surface 40b of the absorbent core 40. Is covered. The absorbent core 40 and the core wrap sheet 41 may be joined by a known joining means such as a hot-melt adhesive.

  As shown in FIG. 1 and FIG. 2, side sheets 62 each having a thread-like elastic member 61 fixed in an extended state are arranged on one side edge of each side part along the longitudinal direction X of the diaper 1. A pair of three-dimensional gathers are formed in the crotch part C when worn. Further, between the top sheet 2 and the back sheet 3 in the left and right leg portions disposed around the wearer's legs, a thread-like elastic member 63 is disposed in a stretched state along the longitudinal direction X. A pair of leg gathers is formed in the leg portion at the time by the contraction of the elastic member 63. A belt-like elastic member 64 extends along the width direction Y between the top sheet 2 and the back sheet 3 at the waist portions (end portions in the longitudinal direction X) of the back side portion A and the ventral side portion B. It is arranged in a state and a waist gather is formed. The pair of side sheets 62 and 62, the top sheet 2, the absorber 4, the elastic members 63 and 64, and the back sheet 3 are joined to each other by a known joining means such as a hot-melt adhesive.

  As shown in FIG. 1, a pair of fastening tapes 8, 8 are provided on both side edges along the longitudinal direction X of the back side A of the diaper 1. More specifically, the both sides along the longitudinal direction X of each of the back side portion A and the ventral side portion B extend outward in the width direction Y from both side edge portions along the longitudinal direction X of the absorbent body 4. A pair of side flaps 7 and 7 is formed, and a fastening tape 8 is attached to each of the pair of side flaps 7 on the back side A so as to extend outward in the width direction Y. A fastening part 81 made of a male member of a mechanical surface fastener is attached to the fastening tape 8.

  In addition, a non-skin facing surface of the ventral side B of the diaper 1 is formed with an attachment region 9 made of a female member of a mechanical surface fastener. The to-be-attached region 9 is formed by bonding and fixing a female member of a mechanical surface fastener to the non-skin facing surface of the back sheet 3 by a known joining means (for example, an adhesive or heat seal). The fastening part 81 of the tape 8 can be detachably fastened.

  The diaper 1 of the present embodiment increases the absorbability of excretory fluids such as urine and loose stool so that the excretory fluids are less likely to adhere to the wearer's skin, and has such effects. Therefore, the top sheet 2, the absorbent core 40, and the core wrap sheet 41 are devised, and these contrivances are the main features of the present embodiment. Hereinafter, main features of the diaper 1 of the present embodiment will be described.

  As shown in FIGS. 2 and 3, the topsheet 2 in the present embodiment has a large number of convex portions 25 that protrude toward the wearer's skin. A large number of concave portions 26 are formed in addition to the large number of convex portions 25 on the skin facing surface of the topsheet 2, and an uneven shape including the large number of convex portions 25 and concave portions 26 is formed. As shown in FIG. 2, the uneven shape of the skin facing surface of the topsheet 2 is formed at least above the absorbent core 40 in the crotch part C (the excretory part facing part), and in this embodiment Furthermore, it is also formed above the absorbent core 40 in each of the back side portion A and the ventral side portion B. On the other hand, the non-skin facing surface (facing surface of the absorber 4) of the top sheet 2 is a flat surface having no unevenness.

  The surface sheet 2 will be further described. As shown in FIG. 3, the surface sheet 2 has an upper layer 20 directed toward the wearer's skin and a lower layer 21 disposed on the absorber 4 side. The upper layer 20 and the lower layer 21 are partially bonded to each other at the bottoms of the numerous recesses 26, and the bottoms of the respective recesses 26 serve as bonding portions between the upper layer 20 and the lower layer 21. The upper layer 20 protrudes toward the wearer's skin side at a portion other than the bottom portion (joint portion) of the concave portion 26 to form a convex portion 25. A space is formed in the convex portion 25. The convex portion 25 has a rectangular bottom surface. Further, the convex portion 25 is a flat rectangular parallelepiped or truncated quadrangular pyramid having rounded ridge lines as a whole. On the other hand, the concave portion 26 (joint portion) is also rectangular.

  The convex portions 25 and the concave portions 26 (joining portions) are arranged alternately and in a row in one direction. In the present embodiment, as shown in FIG. 3, the convex portions 25 and the concave portions 26 are alternately arranged along the width direction Y of the diaper 1 to form a row. The row | line | column which consists of the convex part 25 and the recessed part 26 extended in this width direction Y is arrange | positioned at multiple rows over the longitudinal direction X of the diaper 1. FIG.

  In the surface sheet 2, when attention is paid to any one convex portion 25 in one row extending in the width direction Y of the diaper 1, in another row adjacent to the row, the one convex portion 25 is adjacent. The convex part 25 is not located in the matching position. “A convex part is not located at a position adjacent to one convex part” means that the convex part 25 is not located at the same position in an adjacent row when attention is paid to one convex part 25. It means that. That is, the convex part 25 is not arrange | positioned so that the convex part 25 between adjacent row | line | columns may continue completely regarding the longitudinal direction X of the diaper 1 in FIG. Accordingly, a part of the convex part 25 and a part of the concave part 26 (joining part) may be present at a position adjacent to the single convex part 25, or only the concave part 26 may be present. good. In the present embodiment, in the row of two adjacent convex portions 25, the concave portions 26 are arranged so as to be shifted by a half pitch. Therefore, when attention is paid to any one concave portion 26 in one row, the single concave portion 26 is a closed concave portion formed by being surrounded by the convex portions 25 in the front and rear and left and right. That is, the concave portions 26 (joining portions) are arranged in a staggered pattern. Accordingly, the convex portions 25 are similarly arranged in a staggered pattern.

  Thus, when the uneven | corrugated shape which consists of many convex parts 25 and the recessed parts 26 (joining part) is formed in the skin opposing surface of the surface sheet 2, the excrement liquid, especially the soft stool which is highly viscous excretion liquid, is a recessed part. 26, it is difficult to diffuse in the surface direction, and the lateral flow of soft stool is suppressed. In addition, the excretion fluid such as loose stool is captured in the recess 26, so that the downward movement of the excretion fluid (that is, the absorber direction) is promoted, and as a result, the leakage of the excretion fluid is prevented. In particular, in this embodiment, since a space is formed in the convex portion 25, the transition path from the bottom (joint portion) of the concave portion 26 to the excretion fluid trapped in the concave portion 26 is the lower side. In addition to the path toward the direction (absorber direction), there is a path from the side of the convex part 25 surrounding the concave part 26 to the downward direction via the space in the convex part 25, so It excels in the excretion of the excretory fluid and reduces the chances of the excretory fluid contacting the skin.

From the viewpoint of more surely exhibiting the operational effects due to the uneven shape of the topsheet 2, it is preferable to set the dimensions and the like of the convex portions 25 as follows.
The height H (see FIG. 3) of the convex portion 25 is preferably 1 to 10 mm, more preferably 3 to 6 mm.
The bottom dimension W1 (see FIG. 3) of the convex portion 25 along the width direction Y of the diaper 1 is preferably 2 to 30 mm, more preferably 2 to 5 mm, and the longitudinal direction X (the convex portion 25 and the concave portion 26 of the diaper 1). The bottom dimension W2 (refer to FIG. 3) along the direction orthogonal to the row direction of the column is preferably 2 to 30 mm, more preferably 2 to 5 mm.
The bottom area of the convex portion 25 is preferably 4 to 900 mm ² , more preferably 4 to 25 mm ² .
The length W3 (see FIG. 3) of the concave portion 26 (joint portion) in the width direction Y of the diaper 1 (the row direction of the convex portion 25 and the concave portion 26) is preferably 0.1 to 20 mm, more preferably 0.5 ~ 5 mm.

  As described above, the convex portions 25 and the concave portions 26 (joining portions) of the topsheet 2 are arranged in a staggered pattern, and the staggered arrangement of the convex portions 25 (the concave portions 26) is shown in FIG. Can be set as follows. 4A shows a pattern in which one convex portion 25 is surrounded by six concave portions 26 (a six-point concave portion pattern), and FIG. 4B shows that one convex portion 25 has four concave portions 26. It is an enclosed pattern (four-point concave pattern), and any pattern is a pattern in which the convex portions 25 are arranged in a staggered manner. In FIG. 4, the positions of the concave portions 26 are shown in 12 rows and 12 columns (the convex portions 25 are not shown), and the hatched portions in the grids shown in FIG. 4 are the concave portions 26. is there.

  The six-point concave pattern shown in FIG. 4A is 6 of (1, 2), (1, 4), (3, 1), (3, 5), (5, 2), (5, 4). A first six-point pattern element (first element) is constituted by the concave portion of the point. Here, the numerical value in () represents (row number, column number). The second element on the right is the six concave portions of (1, 8), (1, 10), (3, 7), (3, 11), (5, 8), (5, 10). It is configured. Further, the third element below the first element shares the concave portions of the two points (5, 2) and (5, 4) below the first element, so that (7, 1), (7, 5 ), (9, 2), (9, 4) and 6 recesses. Further, the fourth element on the right side shares the recesses (3, 5), (3, 7), (5, 4), (7, 5), (5, 8) with any of the first to third elements. And it is comprised by the recessed part of 6 points | pieces combined with the recessed part (7,7). As described above, the skin facing surface of the topsheet 2 shown in FIG. 4A is configured by widely repeating the six-point concave pattern while sharing the partial concave portions 26 of each element.

  In the four-point concave pattern shown in FIG. 4B, the first element is composed of concave parts at four points (1, 3), (3, 1), (3, 5), and (5, 3). Yes. On the right side, the concave portion (3, 5) is shared, and the second element is configured together with the concave portions (1, 7), (3, 9), (5, 7). Below the first element, the concave portion (5, 3) of the first element is shared, and the third element is configured together with the concave portions (7, 1), (7, 5), (9, 3). . Further, the fourth element on the right side is configured by sharing the concave portions (3, 5), (5, 3), (5, 7), (7, 5) with any one of the first to third. As described above, the skin facing surface of the topsheet 2 shown in FIG. 4B is configured by widely repeating the four-point concave pattern while sharing a part of the concave portions 26 of each element.

  In the arrangement pattern of the recesses 26 (joint portions) shown in FIG. 4A and FIG. 4B, the protrusions 25 (in the approximate center of each element formed by the six to four recesses 26 ( It is preferable that the top part of the convex part 25 is arranged. For example, referring to the first to fourth elements of the six-point recess pattern in FIG. 4A, (3, 3) of the first element, (3, 9) of the second element, (7, 3 of the third element) ), And the top of the convex portion 25 is preferably arranged at (5, 6) of the fourth element. Further, in terms of the first to fourth elements of the four-point concave pattern in FIG. 4B, (3, 3) of the first element, (3, 7) of the second element, (7, 3 of the third element) ), The top of the convex portion 25 is preferably arranged at (5, 5) of the fourth element. By arranging the convex portions 25 in a staggered pattern in this way, the pressure that comes into contact with the wearer's skin is evenly distributed, and a better cushioning property is realized. Since the effect is exhibited in the entire sheet, it is preferable.

  The upper layer 20 and the lower layer 21 which comprise the surface sheet 2 consist of a sheet-like thing of the same or different fiber material. This sheet-like material is substantially non-stretchable. The substantially non-stretchable sheet-like material means, for example, an elongation limit of 105% or less, and material elongation or permanent deformation occurs when the elongation limit is exceeded. As such a sheet-like material, any material that is substantially non-stretchable in a material used as a surface sheet in a conventionally known absorbent article can be used without particular limitation. Various nonwoven fabrics such as manufactured nonwoven fabric, spunbonded nonwoven fabric, melt blown nonwoven fabric, spunlace nonwoven fabric, and needle punched nonwoven fabric; and films made liquid-permeable by opening means. When using a nonwoven fabric as the sheet material of the upper layer 20 and the lower layer 21, the fineness of the constituent fibers is preferably 1 to 20 dtex, particularly 1.5 to 4 dtex, from the viewpoints of securing the strength of the surface sheet and improving the touch. . Both the upper layer 20 and the lower layer 21 are preferably subjected to a hydrophilic treatment using a surfactant or the like.

The basis weight of the upper layer 20 is preferably 10 to 100 g / m ² , particularly preferably 10 to 30 g / m ² . On the other hand, the basis weight of the lower layer 21 is preferably 5 to 50 g / m ² , particularly preferably 10 to 30 g / m ² . Total basis weight of the surface sheet 2, including an upper 20 and lower 21, 15~150g / m ^2, it is particularly preferably 20 to 60 g / m ^2.

  The topsheet 2 having such a concavo-convex shape can be manufactured by using a known embossing process. For example, the upper layer 20 is made of a second roll having a first roll having a concavo-convex shape on the peripheral surface and a concavo-convex shape meshing with the concavo-convex shape of the first roll on the peripheral surface. The raw material of the upper layer 20 is unevenly shaped by being engaged with the meshing part with the roll, and then the original material of the upper layer 20 and the original material of the lower layer 21 which are unevenly shaped are overlapped to form a laminate. Then, the surface sheet 2 having an uneven shape as shown in FIG. 3 and FIG. 4 is obtained by heating and pressurizing the laminate and joining the two original fabrics by heat fusion. About the surface sheet 2 which concerns on this embodiment, the content of the patent document 1 which concerns on an earlier application of this applicant can be applied suitably.

  Moreover, in this embodiment, in addition to the device of the surface sheet 2 described above, the absorbent core 40 is further devised. That is, in the absorbent core 40 according to the present embodiment, as shown in FIGS. 1 and 2, the slit 5 having the opening 50 on at least the non-skin facing surface 40 b side of the absorbent core 40 has the absorbent core 40. It extends in the longitudinal direction X. In the absorbent core 40, a plurality of (two) continuous linear (rectangular) slits 5 extending in the longitudinal direction X are formed at predetermined intervals in the width direction Y of the absorbent core 40. These two slits 5 and 5 are parallel to each other and have the same length in the longitudinal direction X, and are formed symmetrically across an imaginary straight line (not shown) that bisects the absorbent core 40 in the width direction Y. . The interval between the two slits 5 and 5 is preferably 10 to 50 mm.

  The slit 5 is formed at least in the crotch part C (the excretory part facing part). As shown in FIG. 1, the slit 5 in this embodiment passes through the crotch part C (the excretory part-facing part) from the vicinity of the longitudinal end of the absorbent core 40 on the back side part A side. It extends continuously and linearly over the part near the crotch C, and the length at the abdomen B is shorter than the back side A and the crotch C, and includes the crotch C. It is biased toward the dorsal side A side. Such a formation position of the slit 5 in the present embodiment corresponds to a region where soft stool is excreted and the vicinity thereof.

  The slit 5 deposits the forming material of the absorbent core 40 in the deposition process of the forming material of the absorbent core 40 (fiber material such as wood pulp, particles of water-absorbing polymer, etc.) at the time of manufacturing the absorbent core 40. This is a site formed by intentional inhibition, and the slit 5 has substantially no material for forming the absorbent core 40. “Substantially no material is formed in the slit” means that the material for forming the absorbent core 40 is unintentionally present in the slit 5 (based on the basis weight of the periphery of the slit 5 in the absorbent core 40). Also exists at low basis weights).

  The absorbent core 40 having the slits 5 can be manufactured in accordance with a conventionally known method for manufacturing an absorbent core. For example, the material for forming the absorbent core 40 supplied on an air flow is applied to the outer peripheral surface of the rotating drum. In the method of obtaining the absorbent core 40 by sucking and depositing on the formed mold, the mold has a predetermined pattern as the mold (for example, a portion corresponding to the slit 5 protrudes upward compared to the peripheral portion. In the absorbent core 40 thus obtained, the portion where the forming material is not deposited (the portion where the forming material is not substantially present) is the slit 5.

  As shown in FIG. 2, the slit 5 in the present embodiment does not penetrate the absorbent core 40 in the thickness direction, and covers the skin facing surface 40 a of the absorbent core 40 in the slit 5 and the core wrap sheet 41. The material for forming the absorbent core 40 is deposited between the portions [that is, the portion of the absorbent core 40 adjacent to the slit 5 in the thickness direction of the absorbent core 40 (the side opposite to the opening 50)]. Thus, the opening facing portion 40c is formed. The opening facing portion 40c is not compressed in the thickness direction at the time of manufacturing the absorbent core 40, and thus is not consolidated, like the portions other than the slit 5 in the absorbent core 40.

  The non-consolidated opening facing portion 40c is obtained by forming the slit 5 without intentionally depositing the forming material of the absorbent core 40 in the manufacturing method of the absorbent core 40 described above. A method other than the slit forming method, for example, manufacturing an absorbent core having no slit, and subjecting a predetermined portion of the absorbent core to post-processing such as embossing, die cutting, and cutting. It cannot be obtained by the method of forming. Since these post-processing compresses the absorbent core in the thickness direction, the opening facing portion adjacent to the slit obtained through the post-processing in the thickness direction is consolidated by the post-processing. Because.

  In addition, the density of the opening facing part 40c which is not consolidated is usually 5 mm from the peripheral part of the opening facing part 40c in the absorbent core 40 (excluding the slit 5 from the opening facing part 40c in the absorbent core 40). The density is less than or equal to the density of The reason why the non-consolidated opening facing portion 40c has a lower density than its peripheral portion is as follows. That is, in the conveyance process after the formation of the slit 5 (opening facing portion 40c) at the time of manufacturing the absorbent core 40, pressure is applied to the entire absorbent core 40 by various rolls such as a conveyance roll in the thickness direction. In addition, the peripheral portion of the opening facing portion 40c may be compressed to some extent by the pressure to increase the density, whereas the opening facing portion 40c has a substantial thickness (absorbent core 40) compared to the peripheral portion. Therefore, it is hardly subjected to the pressure and is not substantially compressed. That is, at the time of manufacturing the absorbent core 40, the density of the opening facing portion 40c does not substantially change, whereas the density of the peripheral portion may increase due to compression or the like during transportation. The density of the opening facing portion 40c is relatively low.

  Since the slit 5 in which the material for forming the absorbent core 40 does not substantially exist is formed in the absorbent core 40 so as to extend in the longitudinal direction X of the absorbent core 40, the crotch portion C faces the excretory part. Since the excretion fluid such as loose stool that has been excreted locally in the part rapidly diffuses in the longitudinal direction X of the absorbent core 40 using the slit 5 as a conduction path, the excretion fluid is substantially absorbed by the absorbent core 40. The portion increases, thereby reducing wetback such as urine and loose stool. In particular, in the initial excretion, the slit 5 functions as a storage unit for temporarily storing the initial excretory liquid, so that the absorbability of excreted liquid such as loose stool is improved.

  Moreover, in this embodiment, as above-mentioned, the slit 5 does not penetrate the absorptive core 40 in the thickness direction, and the absorptivity is formed on the skin facing surface 40a side of the part where the slit 5 is formed in the absorptive core 40. Since there is a non-consolidated opening facing portion 40c formed by depositing the forming material of the core 40, the surface sheet 2 and the core wrap sheet 41 are sequentially transmitted to face the skin of the absorbent core 40. The excretory fluid that has reached the surface 40a is diffused in the width direction Y at the opening facing portion 40c, thereby making it possible to use the entire absorbent core 40 for absorbing and retaining excretory fluid, such as urine and loose stool The effect of reducing the wetback is further improved.

  If the opening facing portion 40c does not exist, that is, the slit 5 penetrates the absorbent core 40 in the thickness direction (the slit according to the present invention includes such a through-type slit). In addition, since the diffusion of the excretory fluid in the width direction Y is interrupted by the through-type slit 5, the effect of improving the utilization efficiency of the absorbent core 40 cannot be expected so much. Further, when the opening facing portion 40c exists but is consolidated [the opening facing portion 40c is a part other than the slit 5 in the absorbent core 40 (for example, the periphery of the opening facing portion 40c). In the case where the density is higher than that of the part 4), the excretion fluid flows on the skin facing surface of the absorbent body 4 (the face facing the top sheet 2) and is difficult to enter the absorbent body 4; The diffusion effect of the excretory fluid in the width direction Y is not sufficiently obtained.

  The width of the slit 5 is gradually increased from the skin facing surface 40a side of the absorbent core 40 toward the non-skin facing surface 40b side (see FIG. 1, the length in the direction Y perpendicular to the extending direction X of the slit 5). It has a part that has. The slit 5 in the present embodiment has a trapezoidal shape (isometric leg) in a cross-sectional view in the width direction Y as shown in FIG. 2, and the width W4 of the entire slit 5 is non-skin from the skin facing surface 40a side. It gradually increases toward the facing surface 40b. When the width W4 of the slit 5 gradually increases from the skin facing surface 40a side to the non-skin facing surface 40b side in this way, for example, when the width W4 does not change in the thickness direction of the absorbent core 40 ( For example, the liquid diffusion on the non-skin-facing surface side of the absorbent body 4 (absorbent core 40) is further improved as compared with a case where the sectional view of the slit 5 is a rectangular shape.

  From the viewpoint of ensuring the above-described effects by the slit 5 more reliably, the width W4 (see FIG. 1) of the slit 5 is preferably 1 to 20 mm, more preferably 1 to 10 mm. Further, the width W4s of the narrowest portion of the slit 5 is preferably 1 to 10 mm, and more preferably 1 to 5 mm. From the same point of view, the total W50 of the width W4s of the narrowest portion of all the slits 5 existing in the crotch C with respect to the full width W0 in the width direction Y of the absorbent core 40 in the crotch C (the excretory part facing portion). The ratio (W50 / W0) is preferably 0.02 to 0.3, more preferably 0.05 to 0.25.

  Moreover, in this embodiment, in addition to the device of the surface sheet 2 and the absorptive core 40 mentioned above, the core wrap sheet 41 is further devised. That is, the portion of the core wrap sheet 41 that covers the skin facing surface 40a of the absorbent core 40 (the portion disposed between the topsheet 2 and the absorbent core 40) is a low-viscosity liquid measured by the following method. The liquid permeation time of (saline) is 2.5 seconds or less, preferably 0.5 to 2.5 seconds, more preferably 0.5 to 2 seconds, and particularly preferably 0.5 to 1.5 seconds. . The core wrap sheet 41 in the present embodiment has the same configuration as a whole, and the liquid permeation time (including the liquid permeation time of a highly viscous liquid described later) in an arbitrary part is in a specific range. The core wrap sheet 41 having the liquid permeation time in the above range is particularly excellent in liquid permeability of excretory liquid having a relatively low viscosity such as urine, and can quickly allow urine to permeate the absorbent core 40 side.

<Measurement method of liquid permeation time of low viscosity liquid>
As shown in FIG. 5, two cylinders 91 and 92 having an inner diameter of 35 mm with upper and lower ends opened are arranged up and down with the axes of both cylinders 91 and 92 being aligned, and an 8 cm square measurement target sheet S ( A core wrap sheet is sandwiched between the upper and lower cylinders 91 and 92. At this time, it is preferable that the upper and lower cylinders 91 and 92 are connected by fitting the clip 93 to an annular flange portion provided at the lower end of the upper cylinder 91 and the upper end of the lower cylinder 92. Reference numeral 94 denotes a rubber packing having a through hole having the same diameter and the same shape as the inner diameters of the cylinders 91 and 92. In this way, with the measurement sheet S sandwiched and fixed between the upper and lower cylinders 91 and 92, a physiological saline (Japanese Pharmacopoeia physiological saline Otsuka raw food injection indicated by symbol W in FIG. 5 is placed in the upper cylinder 91. 40 g ± 1 g is used. The physiological saline is supplied into the upper cylinder 91 from a container (such as a beaker) (not shown) containing 40 g ± 1 g of physiological saline in a lump (from the container into the cylinder 91). It is carried out by injecting the saline flow into the upper cylinder 91 (continuing to the end without interruption). Saline is acclimatized for one day in a thermostatic chamber at 23 ° C. and 50% RH before use. The supplied physiological saline passes through the measurement target sheet S or is absorbed by the measurement target sheet S and disappears from the upper cylinder 91. The time from the start of the supply of the physiological saline to the time when the physiological saline reaches the same position as the surface of the measurement target sheet S (the surface on the upper cylinder 91 side) is measured. The transmission time.

  Moreover, the site | part (site | part arrange | positioned between the surface sheet 2 and the absorptive core 40) which coat | covers the skin opposing surface 40a of the absorptive core 40 in the core wrap sheet | seat 41 has the liquid permeation | transmission time 2 of a low viscosity liquid. In addition to the second or less, the liquid permeation time of the highly viscous liquid (mixed liquid of glycerin and ion-exchanged water) measured by the following method is 500 seconds or less, preferably 50 to 300 seconds, more preferably 50 to 200 seconds. The core wrap sheet 41 in which the liquid permeation time is in the above range is particularly excellent in liquid permeability of excretory liquid with relatively high viscosity such as loose stool, and the stool can be quickly permeated to the absorbent core 40 side.

<Measurement method of liquid permeation time of highly viscous liquid>
Measurement is performed according to the above <Method for measuring liquid permeation time of low-viscosity liquid> except that 10 g ± 1 g of high-viscosity liquid having a viscosity of 290 mPa · s is used instead of 40 g ± 1 g of physiological saline. 10 g ± 1 g of highly viscous liquid is fed into the upper cylinder 91 at a speed of 100 g / ml by a digital pump (Cole-Parmer Instrument Company, trade name “Masterflex”). The time until the liquid level of the highly viscous liquid reaches the same position as the surface of the measurement target sheet S (the surface on the upper cylinder 91 side) is measured, and this time is defined as the liquid permeation time of the highly viscous liquid. A highly viscous liquid is prepared as follows. That is, glycerin and ion-exchanged water are mixed at a mass ratio of the former: the latter = 94: 6, and 0.01 g of Red No. 2 is added to this mixed solution with respect to 100 g of the mixed solution. A highly viscous liquid is prepared. The highly viscous liquid is allowed to acclimate for 1 day in a thermostatic chamber at 23 ° C. and 50% RH before use.

As an example of the core wrap sheet 41 in which the liquid permeation time of each of the low-viscosity liquid and the high-viscosity liquid is in the above range, the softness bleaching kraft pulp having a freeness of 400 to 550 ml is mainly used, and a paper strength enhancer is added. Examples include thin paper having a basis weight of 10 to 14.5 g / m ² and a density of 0.05 to 0.2 g / cm ³ . Hereinafter, this thin paper will be described.

  The thin paper (core wrap sheet 41) contains softwood bleached kraft pulp (NBKP) having a freeness of 400 to 550 ml as an essential component. In addition, when the thin paper contains 2 or more types of NBKP, the freeness of the aggregate of these 2 or more types of NBKP should just be 400-550 ml. Freeness is a value indicated by Canadian Standard Freeness (C.S.F.) specified in JIS P8121, and is a value of pulp beating (a process of mechanically tapping and grinding pulp in the presence of water). It is a value indicating the degree. Usually, the smaller the freeness value, the stronger the degree of beating, the greater the damage of the fibers due to beating, and the more fibrillation proceeds. NBKP in which the freeness is in the above range is easily entangled with each other because fibrillation is progressing. Therefore, from the viewpoint of improving liquid permeability, the basis weight of the thin paper is reduced (reducing density). Even if the number of interfiber bonding points decreases, the strength of each interfiber bond is higher than that of NBKP in which the freeness exceeds 550 ml and the fibrillation has not progressed relatively. Therefore, a thin paper mainly composed of NBKP having a freeness of 400 to 550 ml can have good strength characteristics.

  The freeness of NBKP used in the present invention is preferably 475 to 525 ml, more preferably 490 to 510 ml. When the freeness is less than 400 ml, the strength improvement effect due to the entanglement of the fibers is saturated, and the fiber cutting is promoted, and the permeation time may be delayed. NBKP beating can be carried out according to a conventional method using a known beating machine such as a beader or a disc refiner with respect to a stock (slurry) in which NBKP is dispersed. Further, as NBKP used in the present invention, NBKP usually used in this type of paper can be used without any particular limitation. As NBKP, ECF (elementary chlorin-free) bleached pulp or TCF (total chlorin-free) bleached pulp that does not use a chlorine compound for pulp bleaching may be used.

  The thin paper is mainly NBKP having a freeness of 400 to 550 ml. Here, “mainly” means that the content of NBKP having a freeness in such a range is 50% by mass or more. The content is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, from the viewpoint of obtaining good strength characteristics.

  The thin paper may contain fibers other than NBKP, and the other fibers may not be hydrophilic cellulose fibers such as NBKP. Other fibers include, for example, hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP) and other wood pulp; Non-wood pulp such as kenaf and hemp; synthetic fibers such as polyester fiber, rayon fiber, acrylic fiber, and the like. The content of these other fibers is preferably 50% by mass or less.

  From the viewpoint of obtaining good strength characteristics (tensile strength), a paper strength enhancer is added to the thin paper (core wrap sheet 41). The paper strength enhancer includes a dry paper strength enhancer that improves the dry paper strength and a wet paper strength enhancer that improves the wet paper strength, either of which may be used. In particular, carboxymethyl cellulose (CMC), which is one type of dry paper strength enhancer, is preferably used in the present invention because it is water-soluble and easy to handle.

  As the dry paper strength enhancer, conventionally known dry paper strength enhancers can be used. For example, carboxymethyl cellulose (CMC) and salts thereof, polyacrylamide resins and salts thereof, cationized starch, polyvinyl alcohol (PVA). These can be used, and one of these can be used alone or in combination of two or more. As the salt of CMC or polyacrylamide resin, sodium salt is mainly used. Examples of the polyacrylamide resin include cationic or anionic polyacrylamide (PAM). Among these dry paper strength enhancers, CMC and salts thereof, anionic PAM and salts thereof are particularly preferable.

  As the wet paper strength enhancer, a conventionally known wet paper strength enhancer can be used. For example, polyamide polyamine epichlorohydrin (PAE), urea-formalin resin, melamine-formalin resin, dialdehyde starch, polyethyleneamine, methylolation Polyamide etc. are mentioned, These 1 type can be used individually or in combination of 2 or more types. Among these wet paper strength enhancers, PAE is particularly preferable.

  The addition amount of the paper strength enhancer in the thin paper is preferably 0.01 to 1.5% by mass, more preferably 0.03 to 1.2% by mass, with respect to the dry mass of all the constituent fibers of the thin paper. . If the added amount of the paper strength enhancer is too small, sufficient strength properties such as tensile strength cannot be obtained. If the added amount of the paper strength enhancer is excessive, the thin paper is hardened (decrease in texture) and the thin paper There is a possibility that the formation of the thin paper may be lowered due to the sticking of the paper to the Yankee dryer or the attachment of the paper strength enhancer to the mesh drum at the time of manufacture.

  The thin paper may contain other components other than the fibers such as NBKP and the paper strength enhancer described above. As other components, for example, fillers such as talc, dyes, color pigments, antibacterial agents, pH adjusters, yield improvers, water resistance agents, antifoaming agents and the like are generally used as raw materials for papermaking and additives. These can be used, and one of these can be used alone or in combination of two or more.

  The thin paper can be produced by a known wet papermaking method. The wet papermaking method includes a stock preparation step for preparing a stock (slurry) made of an aqueous dispersion of fibers such as NBKP, and a paper making step for drying while transporting a fiber made from the stock into a fiber web. It is what has. The paper making process is usually divided into a wire part, a press part, a dryer part, a size press, a calendar part, etc., and is carried out sequentially. The paper strength enhancer described above is usually added to the stock in the stock adjustment process. The wet papermaking method can be carried out according to a conventional method using a paper machine such as a long paper machine, a twin wire paper machine, an on-top paper machine, a hybrid paper machine, or a round paper machine.

From the viewpoint of improving liquid permeability, the thin paper (core wrap sheet 41) has a relatively low basis weight and density. Specifically, the basis weight is 10 to 14.5 g / m ² , preferably Is 11 to 14 g / m ² , and the density is 0.05 to 0.2 g / cm ³ , preferably 0.1 to 0.2 g / cm ³ . When the basis weight and the density are so low, there is a concern about a decrease in paper strength. However, in the present invention, as described above, NBKP having a freeness in a specific range and a paper strength enhancer are used together. It eliminates such concerns. When the basis weight of the thin paper is less than 10 g / m ² or the density is less than 0.05 g / cm ³ , the paper strength may be remarkably reduced, and the basis weight of the thin paper is more than 14.5 g / m ² or the density is 0. If it exceeds 2 g / cm ³ , the effect of improving the liquid permeability may be poor.

The basis weight of the thin paper is measured as follows. After conditioning the sample (thin paper) under the conditions of JIS P8111, a 10 cm square (area 100 cm ² ) measurement piece was cut out from the sample, and the weight of the measurement piece was measured with a two-digit balance below the decimal point. The basis weight of the measurement piece is calculated by dividing the measured value by the area. About 10 measurement pieces cut out from the sample, the basis weight is calculated according to the above procedure, and the average value thereof is taken as the basis weight of the sample.

  The density of the thin paper is measured as follows. 10 sheets of 20 cm square samples (thin paper) are stacked to form a laminated body, and after cooling and solidifying the laminated body with liquid nitrogen, the vicinity of the center of the laminated body is cut with a cutter. Then, of the 10 samples, one having no shear applied to the cross section generated by cutting with the cutter is selected, and the thickness of the selected sample is measured with an optical microscope. In addition, the thickness of the sample is not the length (apparent thickness) from the bottom to the top of the concavo-convex part when the sample has concavo-convex parts such as crepes described later, but the part where the constituent fibers are deposited Length (substantial thickness). The weight of the 20 cm square sample whose thickness has been measured in this way is measured using a balance with two digits after the decimal point. The target density is calculated by dividing the weight of the sample by a value obtained by calculating the volume from the thickness of the sample.

  The thin paper (core wrap sheet 41) may have crepes (crepe-like wrinkles). The crepe in the thin paper may be a wet crepe generated when a wet fiber web (thin paper) is peeled off from a press roll or the like in a press part with a doctor knife or the like in the paper making process at the time of manufacturing the thin paper, or It may be a dry crepe generated when a dry fiber web (thin paper) is peeled off from a Yankee dryer or the like in the dryer part with a doctor knife or the like. The crepe rate is obtained by the following equation. In the following formula, A represents the paper making speed in the paper making process, and B represents the paper winding rotational speed. Crepe rate (%) = (A / B) × 100-100

  Thin paper with crepe has higher liquid permeability than thin paper without crepe, and the higher the crepe rate, the higher the liquid permeability. However, as the crepe rate increases, the strength properties (tensile strength) tend to decrease. The crepe rate of the thin paper (core wrap sheet 41) is preferably 5 to 30%, more preferably 5 to 20%, and particularly preferably 7 to 15% from the viewpoint of the balance between liquid permeability and strength characteristics. .

  If the formation material of each part in the diaper 1 is demonstrated, as the back surface sheet 3, the various things conventionally used in the said technical field can be used. As the back sheet 3, a liquid-impermeable and moisture-permeable sheet can be used. For example, a resin film having moisture permeability, a water-repellent nonwoven fabric, etc. provided with fine holes penetrating the sheet in the thickness direction. Nonwoven fabrics, laminates of these with other sheets, and the like can be used. Moreover, as the side sheet | seat 62, the thing similar to the back surface sheet 3 can be used.

As the absorbent core 40, for example, a fiber assembly made of hydrophilic fibers such as wood pulp or synthetic fiber, or a fiber assembly in which a particulate water-absorbing polymer is held can be used. The density of the absorbent core 40 is preferably 0.03 to 0.2 g / cm ³ , more preferably 0.06 to 0.15 g / cm ³ . When the density of the absorbent core 40 is in the above range, the absorbent body 4 that is soft and has excellent absorption performance can be obtained more reliably.

  The diaper 1 of the present embodiment is used in the same manner as a known unfolded disposable diaper. The diaper 1 of the present embodiment employs characteristic configurations in the above-described topsheet 2, absorbent core 40, and core wrap sheet 41, that is, 1) topsheet 2, 2) having an uneven shape on the skin facing surface. By adopting the absorbent core 40 having the slits 5 extending in the longitudinal direction X, and 3) the core wrap sheet 41 having a liquid permeation time of 2 seconds or less by the measurement method, it excels in the absorption of excretory fluids such as urine and loose stool. Since the excretory fluid is difficult to adhere to the wearer's skin, it is difficult to cause rough skin. In particular, in the topsheet 2, the concavo-convex shape makes it possible to quickly draw the excretion fluid toward the core wrap sheet 41 while suppressing the diffusion of relatively high-viscosity excretion fluid such as loose stool in the surface direction. In the core wrap sheet 41, the excretion liquid such as urine and loose stool is quickly transmitted to the absorbent core 40 side, and the excretion liquid is far from the wearer's skin. In the absorbent core 40, the absorbability of excretory fluids such as loose stool is generally enhanced by the action of the slit 5 in the absorbent core 40, so that the occurrence of wetback is effectively prevented. . In short, the diaper 1 of the present embodiment reduces the chance of contact and the amount of adherence of the relatively low viscosity excretory fluid such as urine to the skin by improving the absorbability of the excreted fluid immediately after excretion and reducing the wetback. In addition to preventing the swelling of the skin due to the adhesion of these excretory fluids, the rough skin is effectively prevented by reducing the chance of contact and the amount of excretory fluids such as loose stool that can irritate the swollen skin. can do.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, in the above-described embodiment, the top sheet 2 has a multilayer structure including the upper layer 20 and the lower layer 21 and is a laminate of a plurality of sheets, but may have a single layer structure including a single sheet. good. Moreover, in the said embodiment, although the elastic member 64 was distribute | arranged to the waist part (end part of the longitudinal direction X) of each back side part A and abdominal side part B, the waist gathers were formed, but waist gathers (elastic member) 64) may be omitted.

  Moreover, in the said embodiment, although the slit 5 extended in the longitudinal direction X of the absorptive core 40 was biased to the back side part A side including the crotch part C, you may form only in the crotch part C. Alternatively, it may be biased to the ventral side B side including the crotch portion C, or continuously over the entire length in the longitudinal direction X without being biased to a specific portion in the longitudinal direction X of the absorbent core 40. It may be formed. The number of slits 5 is not particularly limited, and for example, one slit may be formed at the center in the width direction Y of the absorbent core 40 (on an imaginary straight line that bisects the absorbent core 40 in the width direction Y). Further, the sectional view shape of the slit 5 in the width direction Y is not limited to the trapezoidal shape as shown in FIG. 2, and may be a triangular shape, a square shape, a rectangular shape, or the like.

  In addition, the slit according to the present invention only needs to have an opening at least on the non-skin facing surface side of the absorbent core, and penetrates the absorbent core in the thickness direction. In addition to the facing surface side, an opening may be provided on the skin facing surface side. Moreover, the extending direction of the slit according to the present invention is not limited to the longitudinal direction of the absorbent core (absorbent article), and may be the width direction.

  Moreover, in the said embodiment, the core wrap sheet | seat 41 is one continuous sheet | seat, this sheet | seat is bend | folded along the absorptive core 40, and the both ends of the longitudinal direction X of the absorptive core 40 are remove | absorbed. The entire surface of the core 40 is covered, but instead of this, as shown in FIG. 6, two core wrap sheets 41a and 41b may be used. In the absorbent body 4A shown in FIG. 6, the core wrap sheet 41a covers the entire area of the skin facing surface 40a of the absorbent core 40, and the core wrap sheet 41b covers the entire area of the non-skin facing surface 40b of the absorbent core 40. ing. The core wrap sheet 41b extends outward from both side edges along the longitudinal direction X of the absorbent core 40 in the width direction Y, and the extension is located on the skin facing surface 40a of the absorbent core 40. It is wound up on the lap sheet 41a. The absorbent core 40 and the core wrap sheets 41a and 41b may be joined by a known joining means such as a hot-melt adhesive.

  Further, a sublayer sheet may be interposed between the top sheet 2 and the absorber 4. The sublayer sheet has an effect of reinforcing the liquid absorbing ability of the diaper 1 and reducing a phenomenon (wet back) in which the liquid absorbed by the absorbent body 4 returns to the surface sheet 2 side. As the sublayer sheet, a sheet mainly composed of hydrophilic fibers such as wood pulp (a sheet having a hydrophilic fiber content of preferably 90% by mass or more) can be used. Examples of the sheet include paper, Nonwoven fabrics, webs and the like can be mentioned. The arrangement form of the sub-layer sheet is not particularly limited, and may be arranged from the back side A to the crotch C, or may be arranged from the abdomen B to the crotch C, or the crotch You may arrange | position only to C.

  Further, the present invention can be applied to a pants-type disposable diaper previously formed into a pant-type in addition to a deployable disposable diaper having a fastening tape as in the above-described embodiment, and further, a sanitary napkin, an incontinence pad, etc. It can also be applied to.

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

[Example 1]
An unfolded disposable diaper having the same basic configuration as the diaper 1 shown in FIGS. 1 and 2 was produced and used as a sample of Example 1. As the surface sheet, a sheet having substantially the same structure as the uneven surface sheet having the two-layer structure shown in FIG. 3 is used. As the upper layer and the lower layer of the surface sheet, a liquid-permeable air through having a basis weight of 18 g / m ² is used. A non-woven fabric was used, and the upper layer was formed by embossing the air-through non-woven fabric. The basis weight of the upper layer after providing the irregularities was 23.5 g / m ² . As the back sheet, a liquid-impermeable and moisture-permeable polyethylene resin film (containing calcium carbonate) having a basis weight of 20 g / m ² was used. The absorbent core, as those obtained by holding the particulate water-absorbing polymer in the fiber aggregate, fluff pulp 200 g / m ² and the water-absorbing polymer 186 g / m ² total basis consisting homogeneous mixture of a weight 386 g / m ² An absorbent core was used. The total length of the absorbent core in the longitudinal direction was 360 mm, and the total length in the width direction (maximum length) was 110 mm. As described above, the slit was formed by using a predetermined mold so that the absorbent core forming material was not intentionally deposited at a predetermined site during the manufacture of the absorbent core. As the core wrap sheet, core wrap sheet A1 manufactured by the following method was used.

<Method for producing core wrap sheet A1>
NBKP [trade name “Cariboo” (produced in North America, produced by Cariboo Pulp and Paper Company) and trade name “ARAUCO” (produced in South America, produced by ARAUCO), the content ratio of both pulps is 5 / NBKP prepared by mixing so as to be 5) was uniformly dispersed in water to prepare a slurry having a fiber concentration of 2% by mass, and this slurry was passed through a beater to adjust the NBKP freeness to 500 ml. Furthermore, while diluting this slurry, PAE (trade name “WS4030”, manufactured by Seiko PMC Co., Ltd.) as a wet paper strength enhancer was added in an amount of 0.78% by mass with respect to the dry mass of all the fibers in the slurry. Next, 0.2% by mass of sodium salt of CMC (trade name “Serogen WS-C”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dry paper strength enhancer is added to the dry mass of all fibers in the slurry. The mixture was sufficiently stirred so that each component was uniform, and adjusted to a slurry having a solid content concentration of 0.1% by mass. The slurry thus obtained was spread on a wire mesh paper wire having a wire opening diameter of 90 μm (166 mesh), a paper layer was formed on the wire mesh paper wire, and 6 ml / (cm ² · sec) was formed using a suction box. After the paper layer was dehydrated at a speed, the paper layer was dried with a dryer, and the paper layer was peeled off from the dry surface with a doctor blade, and a crepe was applied at a speed ratio of the dryer and the winding. The thin paper (crepe paper) thus obtained was used as the core wrap sheet A1.

[Example 2]
An unfolded disposable diaper was produced in the same manner as in Example 1 except that the core wrap sheet A2 was used instead of the core wrap sheet A1 in Example 1, and a sample of Example 2 was obtained. The core wrap sheet A2 was manufactured by the same manufacturing method as the above <Method for manufacturing core wrap sheet A1> except that the freeness of NBKP was adjusted to 550 ml.

[Comparative Example 1]
In Example 1, instead of the core wrap sheet A1, an unfolded disposable diaper was produced in the same manner as in Example 1 except that the core wrap sheet B manufactured by the following method was used. did.

<Method for producing core wrap sheet B>
NBKP (manufactured by Cariboo Pulp and Paper Company, trade name “Cariboo”, manufactured in North America, fiber roughness 0.15 mg / m, average fiber length 2.44 mm) is uniformly dispersed in water to give a slurry having a fiber concentration of 2% by mass. The slurry was passed through a beater to adjust the freeness of NBKP to 650 ml. Furthermore, while diluting this slurry, PAE (trade name “WS4030”, manufactured by Seiko PMC Co., Ltd.) as a wet paper strength enhancer was added in an amount of 0.78% by mass with respect to the dry mass of all the fibers in the slurry. The mixture was sufficiently stirred so that each component was uniform, and adjusted to a slurry having a solid concentration of 0.1% by mass. The slurry thus obtained was spread on a wire mesh paper wire having a wire opening diameter of 90 μm (166 mesh), a paper layer was formed on the wire mesh paper wire, and 6 ml / (cm ² · sec) was formed using a suction box. After the paper layer was dehydrated at a speed, the paper layer was dried with a dryer, and the paper layer was peeled off from the dry surface with a doctor blade, and a crepe was applied at a speed ratio of the dryer and the winding. The thin paper (crepe paper) thus obtained was used as the core wrap sheet B.

[Comparative Example 2]
In Example 1, an unfolded disposable diaper was produced in the same manner as in Example 1 except that no slit was formed in the absorbent core, and a sample of Comparative Example 2 was obtained.

[Comparative Example 3]
In Comparative Example 2, an unfolded disposable diaper was produced in the same manner as Comparative Example 2 except that the core wrap sheet B was used in place of the core wrap sheet A1, and a sample of Comparative Example 3 was obtained.

[Comparative Example 4]
In Example 1, instead of the two-layered uneven surface sheet, a flat air-through nonwoven fabric (basis weight 25 g / m ² ) having no unevenness was used as the surface sheet in the same manner as in Example 1 except that it was developed. A diaper was prepared and used as a sample of Comparative Example 4.

[Evaluation]
About each sample (disposable diaper) of an Example and a comparative example, according to the following method, wet back amount, urine absorption time, and loose stool absorbability were evaluated. The results are shown in Table 1 below.

<Wetback amount and urine absorption time>
Spread the disposable diaper flat, place the acrylic sheet with the cylindrical injection part on the surface sheet of the diaper, with the top sheet facing up and fixed on the horizontal surface, and then place a weight on the acrylic sheet A load of ² kPa (20 gf / cm ² ) was applied to the absorber portion. The injection part provided in the acrylic plate has a cylindrical shape (height 53 mm) with an inner diameter of 36 mm. The acrylic plate has a cylindrical part of the cylindrical injection part at a third portion in the longitudinal direction and the central axis in the width direction. A through hole having an inner diameter of 36 mm is formed so that the central axes coincide with each other and communicates between the inside of the cylindrical injection portion and the surface sheet facing surface of the acrylic plate. The core wrap sheet covering the diaper's absorbent core is placed so that the central axis of the cylindrical injection portion of the acrylic plate comes to a position 123 mm from the tip of the ventral portion in the longitudinal direction of the core wrap sheet, and 30 g of artificial urine is injected. Absorbed and allowed to stand for 10 minutes, and further injected 30 g of artificial urine to absorb. Such an artificial urine injection operation was repeated three times, and a total of 90 g of artificial urine was absorbed in the diaper. Next, 20 sheets of 4A filter paper made by Toyo Roshi Kaisha, Ltd (10 cm × 10 cm) are superimposed on the artificial urine absorption site in the diaper, and a load is further applied for 2 minutes on the filter paper to absorb the artificial urine absorbed in the diaper. Absorbed. The load was such that 3.5 kg was applied to an area of 10 cm × 10 cm. After 2 minutes, the load was removed, and the weight of the filter paper that absorbed artificial urine was measured. The weight of the filter paper before artificial urine absorption was subtracted from this weight, and the value was taken as the wetback amount. In the measurement of the wetback amount, the third artificial urine injection time (the time from the start of injection until the entire amount was absorbed into the diaper) was defined as the urine absorption time. The smaller the wetback amount and the shorter the urine absorption time, the better the excretion fluid absorbability and the higher the evaluation.

  The composition of artificial urine is as follows. 1.94% by mass of urea, 0.7954% by mass of sodium chloride, 0.11058% by mass of magnesium sulfate (septahydrate), 0.06208% by mass of calcium chloride (dihydrate), 0.19788% by mass of potassium sulfate , Polyoxyethylene lauryl ether 0.0035 mass% and ion-exchanged water (remaining amount).

<Soft stool absorbability>
With the disposable diaper spread in a flat shape, with the topsheet facing upward and fixed on a horizontal surface, pseudo soft stool 5g, which is a model of a highly viscous liquid, is fixed to the center of the absorber using a syringe from the topsheet side. The batch injection was carried out at a high speed (6 seconds) and left for 5 minutes under a load of 3.5 kPa. At this time, an OHP film (15 × 15 cm) was sandwiched between a weight for applying weight and a disposable diaper. Thereafter, the amount of artificial loose stool adhering to the OHP film was measured, and the measured value was defined as the skin adhesion amount, and the diffusion area of loose stool on the surface sheet was measured. Moreover, the surface sheet was peeled off, and the weight of the artificial stool absorbed by the absorber was measured, and this weight was taken as the amount of soft stool absorption. The smaller the skin adhesion amount and the greater the amount of loose stool absorption, the better the stool absorption and the higher the evaluation. The components of the artificial soft stool are bentonite 110 g, glycerin 45 g, ion-exchanged water 495 g, Emulgen 130K (Kao) 0.35 g, and the viscosity is 300 mPa · s (23 ° C., vibration viscometer: manufactured by A & D Co., Ltd.) VIBRO VISCOMETER CJV5000).

  As is clear from the results shown in Table 1, the disposable diapers of Examples 1 and 2 have a small wetback amount and a short urine absorption time, and loose stool, as compared with the disposable diapers of the comparative examples. With respect to the absorbent article, the amount of skin adhesion is small, the amount of loose stool absorption is large and the diffusion area is small, and thus the excretion fluid such as urine and loose stool is excellent in absorbability, and the excretion fluid is difficult to adhere to the wearer's skin. I know that there is. In Comparative Example 1, the liquid permeation time of the low-viscosity liquid in the core wrap sheet is mainly longer than 2 seconds, and Comparative Examples 2 and 3 are mainly because no slit is formed in the absorbent core. Since Example 4 did not have the convex part which a surface sheet mainly protrudes toward a wearer's skin side, it resulted in being inferior to the excretion liquid absorbency compared with each Example, respectively.

1 disposable diaper (absorbent article)
2 Top sheet 3 Back sheet 4, 4A Absorber 5 Slit 25 Top sheet convex part 26 Top sheet concave part (joint part)
40 Absorbent core 40a Absorbent core skin facing surface 40b Absorbent core non-skin facing surface 40c Opening facing portions 41, 41a, 41b Core wrap sheet 50 Slit opening

Claims (4)

An absorbent body and a surface sheet disposed on the skin-facing surface side of the absorbent body are provided, and the absorbent body includes an absorbent core and a core wrap sheet that covers at least the skin-facing surface of the absorbent core. Absorbent article that has been
The surface sheet has a number of convex portions protruding toward the wearer's skin side,
In the absorbent core, a slit having an opening at least on the non-skin facing surface side of the absorbent core is formed extending in a predetermined direction,
The slit does not penetrate the absorbent core in the thickness direction, and the absorbent core is formed between the slit and a portion of the core wrap sheet that covers the skin facing surface of the absorbent core. The material is deposited to form the opening facing part,
The density of the opening facing portion is the same as or lower than the density of the peripheral portion of the opening facing portion in the absorbent core,
The portion of the core wrap sheet that covers the skin-facing surface of the absorbent core has a liquid permeation time of a low-viscosity liquid measured by the following method of 2.5 seconds or less,
The core wrap sheet is mainly composed of softwood bleached kraft pulp having a freeness of 400 to 550 ml, added with a paper strength enhancer, a basis weight of 10 to 14.5 g / m ² , and a density of 0.05 to 0. Absorbent article that is 2 g / cm ³ thin paper.
<Measurement method of liquid permeation time of low viscosity liquid>
Two cylinders with an inner diameter of 35 mm that open at the top and bottom are placed one above the other with the axes of both cylinders aligned, and the measurement target sheet (core wrap sheet) is sandwiched between the upper and lower cylinders. 40 g ± 1 g of physiological saline is supplied into the cylinder. The physiological saline is supplied into the upper cylinder by injecting the physiological saline into the upper cylinder all at once from a container containing 40 g ± 1 g of physiological saline. The supplied physiological saline passes through the measurement target sheet or is absorbed by the measurement target sheet and disappears from the upper cylinder. The time from the start of the supply of the physiological saline to the time when the surface of the physiological saline reaches the same position as the surface of the measurement target sheet is measured, and the time is defined as the liquid permeation time.   2. The absorption according to claim 1, wherein a portion of the core wrap sheet that covers the skin facing surface of the absorbent core has a liquid permeation time of 0.5 to 2.5 seconds measured by the method. Sex goods.   The absorbent article according to claim 1 or 2, wherein the slit has a portion in which the width of the slit gradually increases from the skin facing surface side of the absorbent core toward the non-skin facing surface side. The absorptive article according to any one of claims 1 to 3 with which space is formed in said convex part of said surface sheet.

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