Absorbent article

Abstract

And the anti-back-seepage property and the diffusivity are simultaneously improved by using a simple structure. The problem is solved by: an absorbent article provided with an absorbent material (50) having an absorbent body (56) that includes a crotch section (M) and is provided within the front and rear LD ranges, and a wrapping sheet (58) that wraps the absorbent body (56), the absorbent body (56) being formed by mixing and aggregating pulp fibers and highly absorbent polymer particles; the absorbent material (50) is provided with a plurality of high-compression parts (51) compressed in the thickness direction (TD) at intervals so as to be recessed from the surface of the absorbent material (50) into the absorbent body (56), portions other than the high-compression parts (51) in the region where the plurality of high-compression parts (51) are arranged are non-high-compression parts (52) which are thicker than the high-compression parts (51) and have a lower density, and the density of the absorbent body (56) in the high-compression parts (51) is 60000-250000 g / m3. And the area of each high compression part (51) is 2-200 mm < 2 >.

Description

Technical Field

[0001] This invention relates to absorbent items such as disposable diapers, sanitary napkins, incontinence pads, and underwear liners (secretion pads). Background Technology

[0002] The absorbent core (also known as absorbent core layer, etc.) of absorbent articles typically contains pulp fibers and highly absorbent polymer particles. As pulp fibers, softwood pulp (NBKP) fibers (pulp fibers derived from softwood trees) are most commonly used. However, in recent years, due to reasons such as the lower cost of hardwood pulp (LBKP) fibers compared to softwood pulp fibers, the use of hardwood pulp fibers (pulp fibers derived from hardwood trees) has also been studied (e.g., Patent Documents 1 and 2).

[0003] However, compared with absorbents made by mixing and aggregating pulp fibers composed solely of coniferous pulp fibers and highly absorbent polymer particles, absorbents made by mixing and aggregating pulp fibers containing both broadleaf and coniferous pulp fibers with highly absorbent polymer particles have the problems of lower liquid diffusivity and lower strength (durability) after liquid absorption.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-014646

[0007] Patent Document 2: Japanese Patent No. 7293479 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Therefore, the main problem of the present invention is to simultaneously improve the strength and liquid diffusivity of absorbents containing hardwood pulp fibers after liquid absorption.

[0010] Technical means for solving problems

[0011] One solution for the above-mentioned problem using absorbent materials is shown below.

[0012] <Option 1>

[0013] An absorbent article characterized by having a crotch area.

[0014] The device includes an absorbent component comprising an absorbent body disposed in a front-to-back direction encompassing the crotch area, and a packaging sheet covering the absorbent body.

[0015] The absorbent is made by mixing and aggregating pulp fibers containing broadleaf pulp fibers and highly absorbent polymer particles.

[0016] The absorbent is provided with a plurality of highly compressed portions along its thickness direction at intervals, such that at least one of the surfaces of the absorbent is recessed into the absorbent body.

[0017] The portion outside the high-compression sections in the arrangement area of ​​the plurality of high-compression sections is a non-high-compression section that is thicker and lower in density than the high-compression sections.

[0018] The density of the absorber in the high-compression section is 60,000~250,000 g / m³.

[0019] The area of ​​each of the high-compression sections is 2~200 mm. 2 .

[0020] (Effects)

[0021] The inventors have discovered that absorbents containing hardwood pulp fibers exhibit poor liquid diffusion and post-absorption strength (durability) because the fiber length of hardwood pulp fibers is shorter than that of softwood pulp fibers. Therefore, to improve low liquid diffusion and post-absorption strength, longer hardwood pulp fiber length is preferred. However, since hardwood pulp fibers are naturally derived, there are limitations in adjusting properties such as fiber length. Furthermore, reducing the proportion of hardwood pulp fibers reduces cost advantages and is therefore not preferred.

[0022] If a high-compression section with the density and area of ​​this design is provided, as will be shown from the experimental results described later, the absorbent containing hardwood pulp fibers can improve the strength and liquid diffusion after liquid absorption. Specifically, the high-compression section is a high-density portion that is compressed in the thickness direction by pressing (direct pressure) and has approximately equal thickness; it is the bottom of a recess that begins to form from at least one of the surface and back sides of the absorbent. This high-density portion has the property that even if it expands due to liquid absorption, the interlacing of fibers is difficult to break. On the other hand, the non-high-compression section is a portion that is thicker and less dense than the high-compression section. However, even near the periphery of the high-compression section in the non-high-compression section, the absorbent is deformed by the deformation and stretching of the high-compression section, resulting in an increase in density closer to the high-compression section. Therefore, capillary action is more pronounced in the high-compression region, not only making the liquid retention better than the surrounding area but also drawing the liquid towards the high-compression section. Therefore, when each high-compression section is spaced apart and has a certain area as in this scheme, the strength of the absorbent after liquid absorption is difficult to decrease. At the same time, the attraction force generated by the capillary phenomenon acts on more excreted liquid, and the excreted liquid absorbed by the absorbent will spread more widely.

[0023] <Second Option>

[0024] An absorbent article characterized by having a crotch area.

[0025] The device includes an absorbent component comprising an absorbent body disposed in a front-to-back direction encompassing the crotch area, and a packaging sheet covering the absorbent body.

[0026] The absorbent is made by mixing and aggregating pulp fibers containing broadleaf pulp fibers and highly absorbent polymer particles.

[0027] The absorbent is provided with a plurality of highly compressed portions along its thickness direction at intervals, such that at least one of the surfaces of the absorbent is recessed into the absorbent body.

[0028] The portion outside the high-compression sections in the arrangement area of ​​the plurality of high-compression sections is a non-high-compression section that is thicker and lower in density than the high-compression sections.

[0029] The shortest distance between each of the plurality of high-compression sections and the nearest other high-compression section is 1 to 4 mm.

[0030] (Effects)

[0031] In this design, by ensuring the arrangement of the high-compression sections is not excessively loose, as demonstrated by the experimental results described later, the strength and liquid diffusion after liquid absorption can be improved in absorbents containing broadleaf pulp fibers. Specifically, the high-compression sections are high-density portions compressed in the thickness direction through pressing (direct pressure), and are approximately equal in thickness. These are the bottoms of recesses that begin to form from at least one of the surface or back of the absorbent. These high-density sections possess the property that the interlacing of fibers is difficult to break even when swollen due to liquid absorption. On the other hand, the non-high-compression sections are thicker and less dense than the high-compression sections. However, even near the periphery of the high-compression sections in the non-high-compression sections, the absorbent deforms by being stretched by the high-compression sections, resulting in an increase in density closer to the high-compression sections. Therefore, capillary action is more pronounced in the high-compression sections, not only improving liquid retention compared to the surrounding areas but also drawing liquid towards them. Therefore, when the high-compression sections are arranged at relatively close intervals as in this scheme, the strength of the absorbent after liquid absorption is difficult to decrease. At the same time, the attraction force generated by the capillary phenomenon acts on more excreted liquid, and the excreted liquid absorbed by the absorbent will diffuse more widely.

[0032] <Third Option>

[0033] According to the first or second embodiment of the absorbent article, the area ratio of the high-compression sections in the arrangement region of the plurality of high-compression sections is 10-35%.

[0034] The diameter of the largest inscribed circle tangent to the shape of the non-high compression portion is 30 mm or less.

[0035] (Effects)

[0036] As in this scheme, if the high-compression sections are arranged particularly densely, the aforementioned liquid diffusivity can be further improved.

[0037] Furthermore, even in the vicinity of the high-compression section, which is not a high-compression section, the absorber is deformed by the deformation and stretching of the high-compression section. As a result, the absorber becomes thinner compared to the case without the high-compression section.

[0038] From these perspectives, it is particularly preferred that the area ratio of the high-compression portion is within the above-mentioned range, and that the diameter of the largest inscribed circle tangent to the shape of the non-high-compression portion is within the above-mentioned range in order to prevent the arrangement of the high-compression portion from being sparse (so that the non-high-compression portion will not be continuous for long distances in all directions).

[0039] Previously, since a dense arrangement of high-compression sections was not considered preferable, the dense arrangement of high-compression sections as in this solution was not considered part of the usual optimization process.

[0040] <Option 4>

[0041] According to the absorbent article of the third embodiment, the high-compression portion has an outline without inflection points or bends, and the diameter of the largest inscribed circle tangent to the outline of the high-compression portion is 1 to 10 mm, and the circumference of the outline of the high-compression portion is 1 to 15 times the circumference of the largest inscribed circle tangent to the outline of the high-compression portion.

[0042] (Effects)

[0043] The size and shape of the high-compression section can be appropriately determined. However, since the high-compression section is a rigid part, if its size is too large, its shape is too long in one direction, or it has an excessively interlaced shape, the overall softness of the absorbent may be insufficient, or it may produce a skin-like sensation (foreign body sensation) as if a foreign object has been mixed into the absorbent. Therefore, the size and shape of the high-compression section are preferably within the range of this solution.

[0044] <Fifth Plan>

[0045] According to the absorbent article of the third or fourth embodiment, in the arrangement area of ​​the plurality of high-compression sections, an imaginary grid is defined, the imaginary grid being formed by repeatedly arranging a first imaginary straight line along a first direction at a first interval in a second direction at a clockwise inclination of 80-90° relative to the first imaginary straight line, and repeatedly arranging a second imaginary straight line along the second direction at a second interval in the first direction.

[0046] And when determining the smallest imaginary quadrilateral with the intersection of the first imaginary line and the second imaginary line as its vertex,

[0047] The high-compression section includes: a first high-compression section disposed at the intersection of the first imaginary line and the second imaginary line; a second high-compression section disposed between adjacent first high-compression sections in the first imaginary line and between adjacent first high-compression sections in the second imaginary line; and a third high-compression section disposed at the intersection of the diagonals of the imaginary quadrilateral.

[0048] The first high-compression section is circular with the intersection of the first imaginary straight line and the second imaginary straight line as its center.

[0049] The second high-compression section is an ellipse or rounded rectangle with a centroid at the midpoint of each side of the imaginary quadrilateral and having a major axis along each side.

[0050] The third high-compression section is an ellipse or rounded rectangle with a centroid at the intersection of the diagonals of the imaginary quadrilateral and a major axis along the front-back direction, or a circle centered at the intersection of the diagonals of the imaginary quadrilateral.

[0051] (Effects)

[0052] The shape and arrangement pattern of the high-compression parts in the high-compression part arrangement area can be determined appropriately. However, if it is the pattern of this solution, the diffusion of the second high-compression part in the long axis direction (first direction and second direction) can be improved. At the same time, since it has both a part that is not a straight line continuous part of the high-compression part in the first direction and a part that is not a straight line continuous part of the high-compression part in the second direction, even if each high-compression part is hardened, the absorber as a whole can easily deform along the body surface.

[0053] <Sixth Plan>

[0054] According to the absorbent article of the fifth embodiment, the diameter of the first high-compression section is 1-4 mm.

[0055] The major axis of the second high-compression section is 3 mm to 6 mm, and the length of the minor axis is equal to the diameter of the first high-compression section.

[0056] The third high-compression section has the same size and shape as the second high-compression section, except that its major axis is oriented in the front-to-back direction.

[0057] The minimum interval between adjacent first high-compression sections and second high-compression sections is 1~2 mm.

[0058] (Effects)

[0059] When the high-compression sections are arranged along the above-mentioned imaginary grid, the size of each high-compression section can be appropriately determined. However, within the range of this solution, not only is the liquid diffusivity improved, but the deformability of the absorbent is also improved, so it is preferred.

[0060] <Seventh Plan>

[0061] According to the fifth or sixth embodiment of the absorbent article, the imaginary grid is an inclined grid shape in which the first imaginary straight line is tilted 40-50° clockwise relative to the front-back direction when viewed from above, and the second imaginary straight line is tilted 40-50° counterclockwise relative to the front-back direction when viewed from above.

[0062] (Effects)

[0063] As described above, when the high-compression sections are arranged along an imaginary grid, such as in this embodiment, the absorbent material exhibits excellent deformability when worn, and the liquid diffusion is also superior, making it a preferred option.

[0064] <Eighth Plan>

[0065] The absorbent article according to any one of the first to seventh embodiments, wherein the unit area weight of the pulp fibers in the absorbent is 100~500 g / m². 2 ,

[0066] The weight ratio of pulp fiber to highly absorbent polymer particles in the absorbent is 40:60~65:35.

[0067] The thickness of the non-high-compression section is 3~13 mm.

[0068] The thickness of the high-compression section is 60-90% of the thickness of the non-high-compression section.

[0069] (Effects)

[0070] Typically, to improve backflow prevention, the mixing ratio of highly absorbent polymer particles with high liquid retention is increased. Furthermore, in recent years, increasing the mixing ratio of highly absorbent polymer particles has also become common to achieve thinner absorbent bodies. However, increasing the mixing ratio of highly absorbent polymer particles not only reduces the shape retention of the high-compression section, but also makes it difficult for the absorbent body to deform due to the stretching effect of the high-compression section in the vicinity of the non-high-compression section, potentially hindering diffusion. Additionally, the close proximity of the highly absorbent polymer particles, which expand due to absorbing excrement, can easily lead to gel blockage, further impeding diffusion. Therefore, it is preferable to set the ratio of pulp fibers to highly absorbent polymer particles in the absorbent body within the range described in this invention, and to compress and form the high-compression section within this range.

[0071] <Ninth Scheme>

[0072] The absorbent article according to any one of the first to eighth embodiments, wherein, in all the pulp fibers of the absorbent, the proportion of pulp fibers with a fiber length of 0.5 mm or more and less than 1.1 mm is 40% or more by mass, and the proportion of pulp fibers with a fiber width of 10 μm or more and less than 35 μm is 90% or more by mass.

[0073] (Effects)

[0074] By combining broadleaf pulp fibers with fibers of average length greater than that, the fiber length distribution of the pulp fibers is achieved as described in this design. This ensures the absorbency capacity and absorption rate of the absorbent, and also provides the fiber's liquid retention capacity due to capillary action, thereby improving backflow prevention. However, there is still room for improvement in liquid diffusivity alone. Therefore, it is preferable to improve liquid diffusivity by combining it with the aforementioned high-compression section.

[0075] <Proposal 10>

[0076] According to the absorbent article of the ninth embodiment, the pulp fibers of the absorbent are composed of coniferous pulp fibers and broadleaf pulp fibers.

[0077] The mass ratio of the broadleaf pulp fiber to the coniferous pulp fiber is 25 / 75 or more and 38 / 62 or less.

[0078] (Effects)

[0079] As can be seen from the experimental examples described later, the pulp fiber of the absorbent is particularly preferred as the proportion of this scheme.

[0080] Invention Effects

[0081] According to the present invention, the absorbent containing broadleaf pulp fibers has the advantage of simultaneously improving the strength and liquid diffusivity after liquid absorption. Attached Figure Description

[0082] Figure 1 This is a top view of the inner surface of a pant-style disposable diaper in its unfolded state.

[0083] Figure 2 This is a top view of the outer surface of a pant-style disposable diaper in its unfolded state.

[0084] Figure 3 yes Figure 1 Sectional view 2-2.

[0085] Figure 4 yes Figure 1Sectional view 3-3.

[0086] Figure 5 (a) is Figure 1 Sectional view 4-4 Figure 5 (b) is Figure 1 Sectional view 5-5.

[0087] Figure 6 This is a 3D model of a pants-style disposable diaper.

[0088] Figure 7 It is a top view that shows the outer surface of the interior component and the outline of the exterior component together in the unfolded state.

[0089] Figure 8 It is a top view that shows the surface of the absorbent along with the outline of the packaging sheet.

[0090] Figure 9 This is a cross-sectional view of the absorber.

[0091] Figure 10 This is a top view of the absorber.

[0092] Figure 11 It is a top view that enlarges the main part of the surface of the absorber.

[0093] Figure 12 This is a top view showing other examples of absorbers.

[0094] Figure 13 This is a cross-sectional view of the absorbent before it is packaged with a packing sheet.

[0095] Figure 14 This is a cross-sectional view of the absorbent component, showing its state after the absorbent is packaged with a packing sheet and before the high-compression section is formed.

[0096] Figure 15 This is a cross-sectional view of another absorber.

[0097] Figure 16 It is a top view that enlarges the main part of the surface of the absorber.

[0098] Figure 17 It is a top view that enlarges the main part of the surface of the absorber.

[0099] Figure 18 It is a top view that enlarges the main part of the surface of the absorber.

[0100] Figure 19 It is a top view that enlarges the main part of the surface of the absorber.

[0101] Figure 20 It is a top view that enlarges the main part of the surface of the absorber.

[0102] Figure 21 It is a top view that enlarges the main part of the surface of the absorber.

[0103] Figure 22 This is a schematic diagram showing the method of manufacturing the absorber.

[0104] Figure 23 This is an explanatory diagram of the method for measuring the depth of the high compression section.

[0105] Figure 24 It is a simplified cross-sectional view of various absorbers.

[0106] Figure 25 This is a schematic diagram showing an example of manufacturing equipment for an absorber.

[0107] Figure 26 This is a schematic diagram showing an example of manufacturing equipment for an absorber.

[0108] Figure 27 This is a simplified side view of the impact testing machine.

[0109] Figure 28 This is a general front view of the impact testing machine. Detailed Implementation

[0110] The following is a detailed description of a trouser-type disposable diaper, using the accompanying drawings as an example of an absorbent article. Adjacent components in the thickness direction, in addition to the fixing or joining portions described below, are also fixed or joined as required, similar to known diapers. The dotted pattern in the cross-sectional view represents adhesives such as hot-melt adhesives used for this fixing or joining method. Hot-melt adhesives can be applied using known methods such as slit coating, continuous linear or dotted droplet coating, spiral, Z-shaped, wavy spraying, or patterned coating (transfer of hot-melt adhesives in relief printing). Alternatively, or simultaneously with the above methods, hot-melt adhesives can be applied to the outer peripheral surface of the elastic component at the fixing portion of the elastic component, thereby fixing the elastic component to the adjacent component. Examples of hot-melt adhesives include EVA-based, adhesive rubber-based (elastic system), polyolefin-based, and polyester / polyamide-based hot-melt adhesives, which can be used without particular limitation. As a method of fixing or joining the constituent components, heat sealing or ultrasonic sealing, which utilizes material welding, can also be used. In areas where liquid permeability in the thickness direction is required, adjacent constituent components in the thickness direction are fixed or joined with an intermittent pattern. For example, when using a hot-melt adhesive for such intermittent fixing or joining, spiral, Z-shaped, wavy, or other intermittent patterns can be appropriately used. When coating is performed over a range greater than the coating width based on a single nozzle, spiral, Z-shaped, wavy, or other intermittent patterns can be applied with or without spacing in the width direction. As a method of joining the constituent components, heat sealing or ultrasonic sealing, which utilizes material welding, can also be used.

[0111] Furthermore, for the nonwoven fabrics described below, any known nonwoven fabric may be used appropriately depending on the application or purpose. As constituent fibers of the nonwoven fabric, in addition to synthetic fibers such as polyethylene or polypropylene (polyolefins), polyesters, and polyamides (including composite fibers such as core-sheath fibers in addition to single-component fibers), regenerated fibers such as rayon or cuprammonium filament, and natural fibers such as cotton may also be selected; there are no particular restrictions, and they may be used in combination. To improve the softness of the nonwoven fabric, it is preferable to make the constituent fibers into crimped fibers. Furthermore, the constituent fibers of the nonwoven fabric may be hydrophilic fibers (including fibers that are hydrophilic using hydrophilic agents), hydrophobic fibers, or water-repellent fibers (including fibers that are hydrophobic using water-repellent agents). In addition, nonwoven fabrics are generally classified according to fiber length, sheet formation method, fiber bonding method, and lamination structure into short fiber nonwoven fabrics, long fiber nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, thermal bonding (hot air) nonwoven fabrics, needle-punched nonwoven fabrics, dot-bonded nonwoven fabrics, and laminated nonwoven fabrics (including SMS nonwoven fabrics with meltblown layers sandwiched between spunbond layers, SMMS nonwoven fabrics, etc.). Any of these nonwoven fabrics can be used.

[0112] Figures 1-6 This illustrates an example of a pant-type disposable diaper. This pant-type disposable diaper includes: a rectangular front outer body 12F forming the front waistband and a rectangular rear outer body 12B forming the rear waistband; and an inner body 200 extending from the front outer body 12F through the crotch area M to the rear outer body 12B, disposed inside the outer bodies 12F and 12B. The two sides of the front outer body 12F and the two sides of the rear outer body 12B are joined to form a side seal 12A. Thus, the openings formed by the front and rear ends of the outer bodies 12F and 12B become waist openings WO for the wearer's torso to pass through, and the portions on both sides of the inner body 200 in the width direction, surrounded by the lower edges of the outer bodies 12F and 12B and the side edges of the inner body 200, respectively, become leg openings LO for the legs to pass through. The inner body 200 is the part that absorbs and retains urine and other excrement, while the outer bodies 12F and 12B are the parts that support the inner body 200 relative to the wearer's body. In addition, the label Y indicates the total length of the diaper in the unfolded state (the front-to-back length from the edge of the waist opening WO of the front panel F to the edge of the waist opening WO of the back panel B), and the label X indicates the total width of the diaper in the unfolded state.

[0113] This type of disposable diaper has: a waist area T defined as the front-to-back direction range of the side seal 12A (from the waist opening WO to the upper end of the leg opening LO); and a middle area L defined as the front-to-back direction range of the part forming the leg opening LO (between the front-to-back direction range of the front panel F with side seal 12A and the back panel B with side seal 12A). The portions of the front outer body 12F and the back outer body 12B located in the waist area T, i.e., the front waist portion and the back waist portion, can conceptually be divided into the "waist portion" W, which forms the edge of the waist opening, and the portion lower than it, i.e., the "lower waist portion" U. Typically, when there is a boundary for the change in stretching stress in the width direction WD within the front and back waist portions (e.g., a change in the fineness or elongation of the elastic component), the waist portion W is defined as the boundary from the side closest to the waist opening WO to the waist opening WO side. When there is no such boundary, the waist extension portion 12E extending from the absorbent body 56 or the inner body 200 towards the waist opening WO side is defined as the waist portion W. These front-to-back lengths vary depending on the product size and can be appropriately determined; for example, the waist portion W can be set to 15-40 mm, and the lower waist portion U can be set to 65-120 mm. On the other hand, the two sides of the middle area L are tapered into a V-shape or curve along the wearer's leg circumference, which becomes the part where the wearer inserts their legs. As a result, the overall shape of the pant-type disposable diaper in the unfolded state is roughly hourglass-shaped.

[0114] (outer body)

[0115] As shown in the example, the outer garments 12F and 12B include a rectangular front outer garment 12F that forms at least the waist portion of the front body piece F, and a rectangular rear outer garment 12B that forms at least the waist portion of the rear body piece B. The front outer garment 12F and the rear outer garment 12B may not be continuous at the crotch side but may be spaced apart in the front-to-back direction LD (two-piece outer garment), or they may be continuous from the front body piece to the rear body piece (one-piece outer garment) (not shown). The front-to-back spacing distance 12d in the two-piece outer garment can be set to approximately 40-60% of the total length Y, for example. In the example shown, the lower edges of the front outer garment 12F and the rear outer garment 12B are formed as a straight line along the width direction WD, but the lower edge of at least one of the front outer garment 12F and the rear outer garment 12B may also be formed as a curve along the leg circumference.

[0116] In a two-piece pant-style disposable diaper, since the inner body 200 is exposed between the front outer body 12F and the rear outer body 12B, a cover nonwoven fabric 13 is preferably provided to span between the rear outer body 12B and the inner body 200 in order to prevent the liquid-proof sheet 11 from being exposed on the back of the inner body 200. The inner and outer surfaces of the cover nonwoven fabric 13 can be bonded to the opposite surfaces respectively using a hot-melt adhesive. The nonwoven fabric used for the cover nonwoven fabric 13 can be, for example, the same nonwoven fabric as the outer bodies 12F and 12B. Alternatively, although not shown, the outer body can also be continuous from the front body piece F to the rear body piece B through the crotch area. In this case, the outer body has not only a portion corresponding to the waist area T, but also a portion corresponding to the middle area L.

[0117] The front outer body 12F and the rear outer body 12B have a front waist portion and a rear waist portion that constitute the waist region T. Figure 1 and Figure 2 In the example shown, the front outer casing 12F and the rear outer casing 12B have the same dimensions in the front-to-back direction LD. Neither the front outer casing 12F nor the rear outer casing 12B has a portion corresponding to the intermediate region L, but... Figure 7 As shown, the rear outer body 12B is longer in the front-to-back direction than the front outer body 12F. The front outer body 12F does not have a portion corresponding to the middle region L, but the rear outer body 12B may have a buttock cover C extending from the waist region T toward the middle region L. Although not shown, a groin cover extending from the waist region T toward the middle region L may also be provided on the front outer body 12F.

[0118] Regarding the outer casings 12F and 12B, such as Figure 4 and Figure 5As shown, the outer and inner sheets adjacent to the outer and inner sides of the elastic members 16-19 described later are joined by a hot-melt adhesive or welding method. Besides being formed from two sheets 12S and 12H as shown in the example, the outer and inner sheets can also be formed from a single sheet. For example, in the latter case, in part or all of the outer bodies 12F and 12B, the inner and outer sheets are formed from the inner and outer portions of a sheet folded back at the edge of the waist opening WO (which may also be the edge on the crotch side). The example shown is an example of the former, where the sheet 12S forming the outer sheet at the lower waist wraps around and folds back to the inner side of the sheet 12H forming the inner sheet at the lower waist, and this folded portion 12r extends to cover the end of the inner body 200 at the waist opening WO side. On the other hand, at the waist, the folded portion 12r becomes an inner sheet adjacent to the inner side of the elastic member.

[0119] In the outer garments 12F and 12B, to improve the fit to the wearer's waist, elastic members 16-19 are built-in, forming a stretchable region A2 that elastically stretches and contracts in the width direction WD along with the expansion and contraction of the elastic members 16-19. Within this stretchable region A2, the outer garments 12F and 12B, in their natural length state, contract with the elastic members, forming wrinkles or pleats. If stretched along the length direction of the elastic members, they can stretch to a preset elongation rate without wrinkles, reaching the point of cut. As for the elastic members 16-19, in addition to elongated elastic members such as rubber threads (example shown in the figure), known elastic members such as strips, meshes, and films can be used without particular restriction. Synthetic rubber or natural rubber can be used as the elastic members 16-19.

[0120] To illustrate the elastic components 16-19 in more detail, multiple waist elastic components 17 are continuously installed at intervals in the front-to-back direction along the entire width direction WD of the outer bodies 12F and 12B at the waist W. Furthermore, one or more waist elastic components 17 arranged in the area adjacent to the lower waist U can overlap with the inner body 200, and can be provided on both sides of its width direction, except for the central portion overlapping with the inner body 200. As for these waist elastic components 17, it is preferable to use materials with a fineness of 155-1880 dtex, particularly around 470-1240 dtex (in the case of synthetic rubber; in the case of natural rubber), and a cross-sectional area of ​​0.05-1.5 mm². 2 Especially 0.1~1.0 mm 2The waist section W has approximately 2 to 15 rubber threads arranged at intervals of 2 to 12 mm, particularly 3 to 7 mm, and preferably 4 to 10 threads. This results in an elongation of 150 to 400% in the width direction WD, particularly preferably 220 to 320%. Furthermore, the waist section W does not need to use elastic components of the same fineness or elongation throughout its entire front-to-back direction LD; for example, the fineness or elongation can be locally different.

[0121] Furthermore, on the lower waist portion U of the outer casings 12F and 12B, multiple lower waist elastic members 16 and 19, each composed of a slender elastic component, are installed at intervals along the front-to-back direction, forming a lower waist stretching area (the area with the lower waist elastic members 16 and 19). As the lower waist elastic members 16 and 19, it is preferable to use materials with a fineness of 155-1880 dtex, particularly around 470-1240 dtex (in the case of synthetic rubber; in the case of natural rubber), with a cross-sectional area of ​​0.05-1.5 mm². 2 Especially 0.1~1.0mm 2 The lower waist portion U has approximately 5 to 30 rubber threads arranged at intervals of 1 to 15 mm, particularly 3 to 8 mm. The resulting elongation in the width direction WD is preferably 200 to 350%, and particularly preferably 240 to 300%. Furthermore, the lower waist portion U does not need to use elastic components of the same fineness or elongation throughout its entire front-to-back direction LD; for example, the fineness or elongation can be locally different.

[0122] As shown in the example of the lower waist U, when elastic members 16 and 19 are provided in the front-to-back direction range of the absorber 56, in order to prevent the absorber 56 from contracting in the width direction WD in part or all of it, as shown in the example... Figure 4 , Figure 5 and Figure 12 As shown, preferably, the middle of the width direction, which includes part or all of the portion overlapping with the absorber 56 in the width direction WD, is designated as a non-stretchable region A1, and the two sides in the width direction are designated as stretchable regions A2 (in the example shown, the stretchable region below the waist). The dimensions of the stretchable regions A2 located on both sides of the non-stretchable region A1 in the width direction can be set approximately constant in the front-to-back direction LD, as shown in the example, or they can vary in the front-to-back direction LD (not shown). Furthermore, the dimensions of the stretchable regions A2 located on both sides of the non-stretchable region A1 in the width direction WD can be set differently, except that the front panel F and the rear panel B are set to be approximately the same.

[0123] After installing elastic components 16-17 and 19 between the inner and outer sheets, the elastic components 16 and 19 are finely cut at a point in the middle of the width direction of the non-stretchable region A1 or throughout the entire region by applying pressure and heating or cutting. This retains stretchability in the stretchable region A2 while eliminating stretchability in the non-stretchable region A1, thus constructing both the stretchable region A2 and the non-stretchable region A1. Furthermore, unwanted elastic components 18 that do not substantially contribute to the formation of stretchability remain in the non-stretchable region A1.

[0124] 12S and 12H can be used without particular restrictions as sheets for forming the inner and outer layers, but nonwoven fabrics are preferred. When using nonwoven fabrics, it is preferable that the weight per unit area of ​​each sheet is 10 to 30 g / m². 2 about.

[0125] The elastic components 16-19 can be fixed to the outer casings 12F and 12B using known methods. Furthermore, the inner and outer sheets can also be joined together using known methods. For example, in the portions of the outer casings 12F and 12B containing the elastic components 16-19, a hot melt adhesive HM can be applied only to the outer peripheral surface of the elastic components 16-19 using a coating mechanism such as a coating gun or a Sure Wrap adhesive nozzle, and sandwiched between the inner and outer sheets. This allows for the fixation of the elastic components 16-19 to the inner and outer sheets, as well as the fixation of the inner and outer sheets, using only the hot melt adhesive HM applied to the outer peripheral surface of the elastic components 16-19.

[0126] (Inner body joint)

[0127] The inner body 200 can be joined to the outer bodies 12F and 12B using methods such as heat sealing, ultrasonic sealing, or hot melt adhesives. In the example shown, the inner body 200 is fixed to the inner surface of the outer bodies 12F and 12B by applying a hot melt adhesive to the back side of the inner body 200, which in this case is the back side of the liquid-impermeable sheet 11 and the root portion 65 of the raised pleats 60. Figure 2 As shown, the inner body joint 20 that joins the inner body 200 and the outer bodies 12F and 12B can be provided on the entire area where the two overlap, for example, it can also be provided on the portion of the inner body 200 excluding the two ends in the width direction.

[0128] (inner body)

[0129] The internal component 200 can be of any shape, but in the example shown, it is a rectangle with a long side extending along the front-to-back direction LD. For example... Figures 3-5As shown, the inner body 200 includes: a top sheet 30 on the body side; a liquid-impermeable sheet 11; and an absorbent member 50 between them. Reference numeral 40 indicates an intermediate sheet (second sheet) provided between the top sheet 30 and the absorbent member 50 to facilitate the rapid transfer of liquid that has permeated through the top sheet 30 to the absorbent member 50. Reference numeral 60 indicates upright pleats 60 extending from both sides of the inner body 200 in contact with the wearer's leg circumference to prevent excrement from leaking to both sides of the inner body 200.

[0130] (Top slide)

[0131] The top sheet 30 has the property of being permeable to liquids; for example, it can be a nonwoven fabric with or without holes, a perforated plastic sheet, etc. Furthermore, the top sheet 30 can be composed of a single sheet or a laminated sheet obtained by bonding two or more sheets together. Similarly, the top sheet 30 can be composed of a single sheet or two or more sheets in the planar direction.

[0132] The two sides of the top plate 30 can be folded back from the side edge of the absorber 50, or they can extend to the side from the side edge of the absorber 50 without folding back.

[0133] To prevent misalignment relative to the back component, it is preferable to use a joining method that utilizes material welding, such as heat sealing or ultrasonic sealing, or a hot melt adhesive to fix the top sheet 30 to the component adjacent to the back side. In the example shown, the top sheet 30 is fixed to the surface of the intermediate sheet 40 and the surface of the portion of the packaging sheet 58 located on the side of the absorber 56 by a hot melt adhesive applied to its back side.

[0134] (Intermediate film)

[0135] To facilitate the rapid transfer of liquid through the top sheet 30 to the absorber 56, an intermediate sheet (also called a second sheet) 40, whose liquid permeation rate is faster than that of the top sheet 30, can be provided. This intermediate sheet 40 is used to rapidly transfer the liquid to the absorber 56, thereby improving the absorption performance of the absorber 56 and reducing backflow from the absorber 56. The intermediate sheet 40 can also be omitted.

[0136] Examples of materials that can be used for the intermediate sheet 40, similar to the top sheet 30, include spunlace nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric, pulp nonwoven fabric, a mixture of pulp and rayon, dot-bonded nonwoven fabric, or crepe paper. Hot-air nonwoven fabric is particularly preferred due to its bulkiness. Hot-air nonwoven fabric preferably uses a core-sheath structure composite fiber; the resin used for the core can be polypropylene (PP), but high-rigidity polyester (PET) is preferred. The area weight is preferably 17~80 g / m². 2 More preferably 25~60 g / m 2The fineness of the raw fiber for nonwoven fabric is preferably 2.0~10 dtex. In order to make the nonwoven fabric fluffy, the mixed fibers used as all or part of the raw fiber are preferably off-center fibers, hollow fibers, or off-center and hollow fibers.

[0137] In the example illustration, the middle layer 40 is arranged in the center with a width smaller than that of the absorbent core 56, but it can also be configured to cover the entire width. The front-to-back length of the middle layer 40 can be the same as the full length of the diaper, the same as the length of the absorbent core 50, or a shorter length centered on the liquid-receiving area.

[0138] To prevent misalignment relative to the back side components, the intermediate sheet 40 is preferably fixed to the component adjacent to the back side by a joining method utilizing material welding, such as heat sealing or ultrasonic sealing, or by a hot melt adhesive. In the example shown, the intermediate sheet 40 is fixed to the surface of the portion of the packaging sheet 58 located on the surface of the absorber 56 by a hot melt adhesive applied to its back side.

[0139] (Liquid-impermeable sheet)

[0140] The material of the liquid-impermeable sheet 11 is not particularly limited. Examples include plastic films made of polyolefin resins such as polyethylene or polypropylene, laminated nonwoven fabrics with plastic films on their surfaces, and laminated sheets with nonwoven fabrics overlapped on plastic films. The liquid-impermeable sheet 11 preferably uses a material that is both liquid-impermeable and moisture-permeable, which is preferred from the viewpoint of preventing stuffiness. As a moisture-permeable plastic film, microporous plastic films are widely used, obtained by compounding inorganic fillers into polyolefin resins such as polyethylene or polypropylene, and then stretching the sheet in a uniaxial or biaxial direction. In addition, a liquid-impermeable sheet can also be used as a liquid-impermeable sheet 11 by using micro denier fiber nonwoven fabric, nonwoven fabric with enhanced leak-proofness by applying heat or pressure to reduce fiber gaps, or coating with superabsorbent resin, hydrophobic resin or water repellent. However, in order to obtain sufficient bonding strength when bonded to the covering nonwoven fabric 13 described later via hot melt adhesive, it is best to use a resin film.

[0141] In addition to the width shown in the figure for housing on the back side of the absorbent member 50, the impermeable sheet 11 can also extend to both sides of the absorbent member 50's top sheet 30 to improve leak-proof performance. A width of approximately 5 to 20 mm on each side is suitable for this extension.

[0142] (Absorbent component)

[0143] The absorbent member 50 has an absorbent body 56 and a packaging sheet 58 that covers the entire absorbent body 56. The absorbent member 50 has portions extending toward the crotch area M and the front and rear sides of the crotch area M.

[0144] (Absorber)

[0145] The absorbent body 56 simply needs to extend along both the front and back sides of the crotch area M, including the crotch area M. In the case of a pant-type disposable diaper as in this example, the absorbent body 56 preferably extends to the periphery of or near the inner body 200 in the front-back direction LD and the width direction WD. Furthermore, the reference numeral 56X indicates the entire width of the absorbent body 56.

[0146] To easily ensure the absorption amount of the crotch area M, the absorbent body 56 is preferably as follows: Figure 8 The example shown is roughly rectangular in shape. Additionally, as... Figure 12 As shown in example (a), in order to improve the fit of the crotch M, the width of the absorbent body 56 of the crotch M can be narrower than its front and rear sides, forming a contracted shape. In this case, in order to easily ensure the absorption amount of the crotch M, the width n1 of the narrowest part of the absorbent body 56 of the crotch M is preferably more than 0.85 times the total width 56X of the absorbent body 56.

[0147] Furthermore, the term "crotch area M" refers to the area in the front-to-back direction LD of the diaper when the absorbent body 56 has a contraction portion 56n (described later). When the absorbent body 56 does not have a contraction portion 56n, but the diaper's shape in its unfolded state as shown in the example has a contraction portion, it refers to the area in the front-to-back direction LD of the diaper's shape with the contraction portion (in the example shown, this is between the front outer body 12F and the rear outer body 12B). When there is no contraction portion, it refers to the portion located in the center of the front-to-back direction LD, and the portion whose front-to-back direction LD dimension is 20-30% of the total product length. The portions extending from the crotch area M to the front and rear sides are respectively called the front portion and the rear portion.

[0148] Absorber 56 can be like Figure 3 and Figure 24 (a) shows a single layer, and it can also be shown as follows: Figure 24 As shown in (b) and (c), multiple layers are stacked. The layers of absorber 56 refer to layers obtained through a fiber-accumulation process using a pre-set fiber-accumulation roller, and a compression process in the thickness direction as needed. Therefore, for example, as... Figure 24 As shown in (b) and (c), the absorber 56 can be composed of two layers: an upper layer 56a and a lower layer 56b.

[0149] Furthermore, the dimensions of the multiple layers comprising the absorber 56 may be the same or different. Additionally, the thicknesses of the multiple layers comprising the absorber 56 may be the same or different. For example, as... Figure 24 As shown in (a), the width and thickness of the upper layer 56a and the lower layer 56b contained in the absorber 56 can be different. Figure 24In the example shown in (b), the width and thickness of the upper layer 56a are smaller than those of the lower layer 56b. The dimensions of the multiple layers contained in the absorbent can be set according to the shape of the absorbent item and its intended use. In addition, the number of layers is not limited to 2, but can also be 3 or more.

[0150] The thickness of the absorbent body 56 (the overall thickness of the multiple layers if the absorbent body is composed of multiple layers) can be 0.5 to 30 mm, preferably 1 to 15 mm. For example, in the case of disposable diapers, the thickness of the absorbent body 56 can be 1 to 30 mm, preferably 1.5 mm to 15 mm, and more preferably 5 mm to 13 mm. Furthermore, in the case of sanitary napkins, the thickness of the absorbent body 56 can be 0.3 mm to 30 mm, preferably 1.0 to 15 mm. The thickness of the absorbent body 56 can be uniform, or it can have areas that are relatively thick or relatively thin.

[0151] The absorbent 56 is formed by mixing and agglomerating pulp fibers 56f and highly absorbent polymer particles 56p. The pulp fibers 56f and highly absorbent polymer particles 56p are generally uniformly distributed throughout the absorbent 56, with the highly absorbent polymer particles 56p remaining between the pulp fibers 56f. Such an absorbent 56 can be manufactured using a fiber stacking roller described later. The absorbent 56 is preferably formed by mixing and agglomerating only pulp fibers 56f and highly absorbent polymer particles 56p, but it may also contain substances other than pulp fibers 56f and highly absorbent polymer particles 56p, such as fillers, pigments, sizing agents, coagulants, oil-resistant agents, sulfuric acid tape, yield improvers, water-filtering improvers, dry paper strength enhancers, wet paper strength enhancers, coloring pigments, water-resistant agents, deodorizers, fragrances, and other additives, as needed.

[0152] (Pulp fiber)

[0153] Pulp is an aggregate of fibers (pulp fibers) extracted from wood, grass, or other plants through mechanical and / or chemical processing. Besides coniferous and broadleaf trees, bamboo, rice, kudzu, miscanthus, hemp, and sugarcane can also be used as raw materials for pulp. Additionally, substances formed from artificial cellulose such as rayon and acetate can also be used.

[0154] The pulp fibers 56f contained in the absorber 56 are preferably a mixture of hardwood pulp fibers (pulp fibers derived from hardwoods) and softwood pulp fibers (pulp fibers derived from softwoods) with an average fiber length longer than hardwood pulp fibers. Alternatively, it may contain only hardwood pulp fibers (100% hardwood pulp fibers). Hereinafter, this absorber 56 will also be referred to as an absorber containing hardwood pulp fibers. The hardwood pulp fibers are preferably bleached hardwood kraft pulp (LBKP) manufactured using the kraft paper process. Coniferous pulp fibers are preferably bleached softwood kraft pulp (NBKP) manufactured using the kraft paper process.

[0155] The content of softwood pulp fiber and hardwood pulp fiber in all pulp fibers 56f is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and even more preferably 98% by mass or more. Furthermore, it is preferable that all pulp fibers 56f are substantially composed of softwood pulp fiber and hardwood pulp fiber. In addition, unless otherwise specified in this specification, the proportion of pulp fiber 56f or its material refers to the absolutely dry additive amount, that is, the mass ratio under absolutely dry conditions.

[0156] As shown in Table 1, in the case of absorbent 56 composed of coniferous pulp fibers in (I), the pulp fibers 56f have larger fiber lengths and widths, and the deviations in fiber length and width are also larger. Therefore, the distance between the pulp fibers 56f is usually larger, resulting in a larger volume of absorbent 56. Consequently, the absorbency (water absorption) of the pulp fibers 56f is large, and the absorption rate of absorbent 56 is relatively fast. However, due to the large distance between the pulp fibers 56f, the liquid retention capacity of the fibers caused by capillary action is relatively low, and the superabsorbent polymer particles (SAP) are more likely to fall off along the direction of gravity, resulting in slightly poorer retention of superabsorbent polymer particles (SAP) between the pulp fibers 56f. As a result, compared with absorbent 56 in (II) and (III) below, the liquid retention capacity of absorbent 56 is reduced, and the effect of inhibiting liquid re-seepage is low.

[0157] [Table 1]

[0158]

[0159] Furthermore, in absorbent 56 composed of broadleaf pulp fibers in (II), the fiber length and width of the pulp fibers 56f are relatively small, and the deviation in fiber length and width is also relatively small. Therefore, the distance between the pulp fibers 56f is reduced, and the fiber density of the resulting absorbent 56 is increased. Consequently, the absorption capacity (water absorption) of the pulp fibers 56f is small, and the absorption rate as absorbent 56 or absorbent article is slower. However, due to the small distance between the pulp fibers 56f, the liquid retention capacity of the fibers is high due to capillary action. In addition, the retention of highly absorbent polymer particles 56p between the pulp fibers 56f is generally good, and the liquid retention capacity of the highly absorbent polymer particles 56p is higher than that of absorbent 56 in (I). As a result, the liquid retention capacity of absorbent 56 is higher than that of absorbent 56 in (I), and it also has the effect of inhibiting liquid backflow.

[0160] (III) In the absorbent 56 composed of softwood pulp fibers and hardwood pulp fibers, fibers with longer fiber length and wider fiber width as described above are combined with fibers with shorter fiber length and narrower fiber width, thereby achieving a fiber density intermediate between (I) and (II). Therefore, the absorbency capacity of the fibers can be ensured to a certain extent, the absorption rate of the absorbent 56 can be maintained, and the liquid retention capacity of the fibers due to capillary action can also be ensured. Furthermore, the retention of highly absorbent polymer particles 56p between the pulp fibers 56f further enhances the liquid retention capacity of the highly absorbent polymer particles 56p compared to (I) and (II). Therefore, the absorbency capacity and absorption rate of the absorbent 56 can be maintained, while also achieving liquid retention capacity. Thus, in the method of (III), by ensuring both absorbency capacity, absorption rate, and liquid retention capacity, backflow prevention can be improved.

[0161] Furthermore, in (III) above, by including coniferous pulp fibers, the bulkiness of the absorbent 56 can be ensured to a certain extent, thus suppressing poor skin feel of the resulting absorbent article. Additionally, by including coniferous pulp fibers, the operability of making fluff pulp from pulp sheets can also be ensured (i.e., suppressing the scattering of powder and the adhesion of fibers to the device). Good operability contributes to the overall high productivity of absorbent article manufacturing.

[0162] In a preferred embodiment of the absorber 56 containing broadleaf pulp fibers, the proportion of pulp fibers with a length of 0.5 mm or more and less than 1.1 mm by mass is 40% or more, and the proportion of pulp fibers with a fiber width of 10 μm or more and less than 35 μm by mass is 90% or more. Furthermore, the proportion of pulp fibers with a fiber length of 0.5 mm or more and less than 1.1 mm is preferably 42.6% or more, more preferably 43% or more, and even more preferably 43.2%, 43.7%, or 45% or more. Additionally, the proportion of pulp fibers with a fiber width of 10 μm or more and less than 35 μm is preferably 90.6% or more, more preferably 91.0% or more, and even more preferably 91.2% or more and 91.4% or more. In this way, by including specific pulp fiber lengths and specific pulp fiber widths within a specific range, the advantages of the absorber 56 (especially its anti-backflow properties) can be further improved, and its reliability can be enhanced.

[0163] In the absorber 56 containing broadleaf pulp fibers, there is no particular upper limit to the proportion of pulp fibers with a fiber length of 0.5 mm or more and less than 1.1 mm. However, considering the variation in fiber length caused by the fact that pulp is a natural material, it can be 80% by mass or less, 60% by mass or less, or 55% by mass or less. Similarly, there is no particular upper limit to the proportion of pulp fibers with a fiber width of 10 μm or more and less than 35 μm. It can be 98% by mass or less, 95% by mass or less, or 94% by mass or less.

[0164] In addition, the fiber length and fiber width of pulp fibers can be measured using a VALMET FS5 measuring machine, according to JIS-P8226:2011 (ISO16065-2:2007) "Pulp - Method for determination of fiber length by means of optical automatic analysis".

[0165] Furthermore, in the absorber 56 containing broadleaf pulp fibers, the average fiber length of pulp fibers with a length of 0.5 mm or more and less than 1.1 mm, measured at 0.02 mm intervals (with a grading width of 0.02 mm), can be 0.5 mm to 0.8 mm, preferably 0.6 to 0.7 mm. Thus, in the absorber 56, the uneven distribution of voids caused by the orientation direction of the pulp fibers can be suppressed, ensuring absorption speed.

[0166] Furthermore, in the absorber 56 containing broadleaf pulp fibers, the standard deviation σ when measuring pulp fibers with a length of 0.5 mm or more and less than 1.1 mm at 0.02 mm intervals (with a grading width of 0.02 mm) can be 0.58 mm or less, preferably 0.56 mm or less, more preferably 0.54 mm or less, and even more preferably 0.50 mm or less. By keeping the standard deviation within the above range, it is possible to improve the absorption capacity and absorption rate of the absorber 56, as well as improve its anti-backflow properties.

[0167] Furthermore, when measuring pulp fibers with a fiber width of 10 μm or more and less than 35 μm at 1 μm intervals (grading widths of 1 μm), the average fiber width can be 15 μm or more and 30 μm or less, preferably 18 μm or more and 27 μm or less. By keeping the average fiber width within the above range, the gaps between fibers can be appropriately maintained, preventing a decrease in absorption rate. At the same time, by avoiding excessive contact area between pulp fibers, excessive increase in the bonding force between fibers can be prevented. This ensures appropriate defiberization during manufacturing. In addition, if the defiberization of the pulp sheet is too low, excessive defiberization (over-defiberization operation) will occur during the production of fluff pulp. Due to the generation of fine fibers, the absorption rate of the resulting absorbent may decrease.

[0168] When measuring pulp fibers with a fiber width of 10 μm or more but less than 35 μm at 1 μm intervals (with a grading width of 1 μm), the standard deviation σ can be 2.9 μm or less, preferably 2.8 μm or less, more preferably 2.75 μm or less, and even more preferably 2.6 μm or less and 2.59 μm or less. By setting the standard deviation within the above range, the absorption rate and anti-backflow effect can be improved.

[0169] As described above, the absorbent 56 containing broadleaf pulp fibers, after reducing the deviation of fiber length distribution and fiber width distribution within a specific range, can still ensure absorption capacity and absorption speed despite the presence of broadleaf pulp fibers, while also having a good anti-backflow effect.

[0170] There are no particular restrictions on the raw wood of the coniferous pulp fibers contained in the pulp fibers, but it is preferred to use pine trees, such as radiata pine, and various fir trees.

[0171] Furthermore, there are no particular limitations on the raw wood for broadleaf pulp fibers; locust wood and eucalyptus wood are suitable. Locust wood is characterized by low shrinkage during drying, high impact resistance, and strength. Pulp made from locust wood inherits these properties, exhibiting high water absorption and drying properties, making it a useful raw material. Eucalyptus belongs to the genus Eucalyptus, among which varieties such as Eucalyptus globulus, Eucalyptus grandis, Eucalyptus urophylla, Eucalyptus nitens, and Eucalyptus regnans have been widely used as raw materials for papermaking since ancient times. Pulp fibers made from these woods have strong compressive strength and high stiffness within the fiber lumen. By using these pulp fibers, the absorbent can achieve high bulk and low density. As a broadleaf pulp fiber, locust wood has higher bulkiness due to its larger fiber width than eucalyptus wood. Even when blended with coniferous pulp fibers, the reduction in its absorption capacity and absorption rate is relatively small, making it a preferred choice.

[0172] The mass ratio of hardwood pulp fiber to other pulp fibers such as softwood pulp fiber in the absorber 56 containing hardwood pulp fiber is not limited. For example, it can be set to 10 / 90 to 90 / 10. However, from an operational point of view, it is preferred to be 20 / 80 to 50 / 50, more preferably 25 / 75 to 38 / 62, even more preferably 25 / 75 or more and less than 38 / 62, even more preferably 26 / 74 to 36 / 64, and particularly preferably 28 / 72 to 35 / 65.

[0173] Furthermore, regarding the content of locust wood material in the raw wood of hardwood pulp fibers, i.e., in the absorbent 56 containing hardwood pulp fibers, the proportion of pulp fibers derived from locust wood material to the total amount of hardwood pulp fibers can be set as follows: preferably 5-95% by mass, more preferably 5% or more by mass and less than 95% by mass, even more preferably 20-93% by mass, 20-90% by mass, 25-85% by mass, and 50-80% by mass. Even for hardwood pulp fibers, which are shorter in length and more prone to dense clogging compared to softwood pulp fibers, the spacing between fibers can be ensured more uniformly regardless of the orientation of the fibers (e.g., in the length direction, width direction, and / or thickness direction of the resulting absorbent article).

[0174] In addition to the aforementioned bleached coniferous kraft pulp and bleached hardwood kraft pulp, other pulp fibers constituting absorber 56 may include soda pulp, sulfite pulp, chemithermomechanical pulp, chemirefining mechanical pulp, and thermochemimechanical pulp. However, if lignin in the fibers cannot be sufficiently removed, the absorption capacity and absorption rate of the pulp fibers tend to decrease; therefore, bleached pulp with sufficiently removed lignin is preferred. When other pulps are included, their content is preferably 10% by mass or less relative to the total pulp raw material.

[0175] Furthermore, the pulp fibers 56f contained in the absorber 56 may contain recycled pulp fibers (recycled pulp fibers) of any type. For example, the pulp fibers 56f may contain recycled softwood pulp fibers and recycled hardwood pulp fibers. When using recycled pulp fibers, the amount of ash in the pulp fibers used in the absorber and the amount of ash in the fluff pulp are preferably as low as possible. In addition, when using recycled pulp fibers, when comparing pulp from the same raw materials before and after recycling, the brightness of the recycled pulp may be lower than that of the original pulp (unrecycled pulp or non-recycled pulp), or it may be the same, preferably the same.

[0176] When the absorbent 56 is multi-layered, it may contain only a portion of broadleaf pulp fibers or all of them. For example, when the absorbent 56 consists of two layers, an upper layer 56a and a lower layer 56b, only the lower layer 56b may contain broadleaf pulp fibers, or only the upper layer 56a, which may come into direct contact with the skin, may contain broadleaf pulp fibers.

[0177] In addition, the unit area weight of pulp fibers 56f in absorbent 56 (when the absorbent is composed of multiple layers, it is the unit area weight of the entire multiple layers) varies depending on the intended use of the product and can range from 100 to 500 g / m². 2 Preferably, it is 100~300 g / m 2 The preferred value is 120~250 g / m³. 2 For example, in the case of disposable diapers, the area weight of pulp fibers can be 100~300 g / m². 2 The preferred value is 120~200 g / m 2 Additionally, for example, in the case of physiological sanitary napkins, the unit area weight of pulp fibers in the absorbent 56 (or the unit area weight of the entire multilayer absorbent when it is composed of multiple layers) can be 150~500 g / m². 2 Preferably, it is 250~400 g / m 2 The weight per unit area of ​​pulp fibers can be uniform overall, or it can form areas with relatively high or relatively low weight per unit area.

[0178] (Highly absorbent polymer particles)

[0179] The superabsorbent polymer particles 56p include both "particles" and "powders". These particles, 56p, can be directly used in disposable diapers. The pre-swelling particle size (particle size before absorbing liquid) of the superabsorbent polymer particles 56p is not particularly limited, but particles with a pre-swelling particle size exceeding 150 μm and below 850 μm are preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more. Furthermore, particles with a pre-swelling particle size shorter than the average fiber length of hardwood pulp fibers (e.g., 600 μm or less, more preferably 500 μm or less) are preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0180] Standard sieves (e.g., standard sieves manufactured by Tokyo Screen Co., Ltd.) with mesh sizes of 850 μm, 600 μm, 500 μm, 355 μm, 300 μm, 250 μm, and 150 μm as specified in JIS Z 8801, along with trays, were arranged sequentially from top to bottom in a vibrator (e.g., Retsch AS200 model). All highly absorbent polymer particles were fed into the top sieve, and then sieving was performed to determine the 56p particle size distribution of the highly absorbent polymer particles. The vibration conditions were 50 Hz, amplitude 0.5 mm, and vibration time 10 minutes. Furthermore, sieving was conducted at a temperature of 23 ± 2°C and a humidity of 50 ± 5%. Before sieving, the samples were stored under the same conditions for at least 24 hours. Sieving was performed three times, and the average of the three measurements was taken as the sieve residue mass for each sieve. Based on the mass of the highly absorbent polymer particles on each sieve and the total mass (mass of all highly absorbent polymer particles), the content ratio (mass percentage) of the corresponding particle size range between each sieve (i.e., greater than 850 μm, greater than 600 μm and less than 850 μm, greater than 500 μm and less than 600 μm, greater than 355 μm and less than 500 μm, greater than 300 μm and less than 355 μm, greater than 250 μm and less than 300 μm, greater than 150 μm and less than 250 μm, and less than 150 μm) can be calculated. Furthermore, if a particle size accumulation curve is obtained based on this particle size distribution, and the particle size corresponding to the cumulative value (50%) at the center of the accumulation curve is taken as the average particle size, then the average particle size of the highly absorbent polymer particles is preferably in the range of 355 to 500 μm, and more preferably in the range of 370 to 470 μm.

[0181] The materials used for the highly absorbent polymer particles 56p can be used without particular limitations, but materials with a water absorption capacity of 40 g / g or more are preferred. The highly absorbent polymer particles 56p can be starch-based, cellulose-based, or synthetic polymer-based (polyacrylate-based, polysulfonate-based, maleic anhydride-based), etc., and can include starch-acrylate (salt) graft copolymers, starch-acrylonitrile copolymer saponifications, sodium carboxymethyl cellulose crosslinks, or acrylate (salt) polymers, etc. The shape of the highly absorbent polymer particles 56p is preferably a commonly used powder or granular form, but other particle shapes can also be used.

[0182] As for the highly absorbent polymer particles 56p, it is preferable to use particles with an absorption rate of 70 seconds or less, especially 40 seconds or less. If the absorption rate is too slow, backflow (the liquid supplied to the absorbent 56 returns to the outside of the absorbent 56) is likely to occur.

[0183] Furthermore, it is preferable to use particles with a gel strength of 1000 Pa or higher as the highly absorbent polymer particles 56p. This effectively suppresses the stickiness after liquid absorption, even when a swollen absorbent body 56 is formed.

[0184] The area weight per unit area of ​​the highly absorbent polymer particles 56p can be appropriately determined according to the absorption capacity required for the application of the absorber 56. Therefore, although it cannot be generalized, the area weight per unit area of ​​the highly absorbent polymer particles 56p in the absorber 56 (when the absorber 56 is composed of multiple layers, it is the area weight per unit area of ​​the entire multilayer structure) can be 50~350 g / m³. 2 Preferably, it is 100~300 g / m 2 For example, in the case of disposable diapers, the area weight of the superabsorbent polymer particles 56p is 50~300 g / m². 2 Preferably, it is 100~250 g / m 2 Additionally, for example, in the case of sanitary napkins, the area weight per unit area of ​​the highly absorbent polymer particles 56p in the absorbent body 56 (or the area weight per unit area of ​​the entire multilayer structure when the absorbent body 56 is composed of multiple layers) can be 70~470 g / m². 2 The preferred value is 140 to 240. When the absorber 56 has two layers, the area weight per unit area of ​​the highly absorbent polymer particles 56p in the lower layer 56b can be different from that in the upper layer 56a. That is, the area weight per unit area of ​​the highly absorbent polymer particles 56p in the lower layer 56b can be greater than that in the upper layer 56a, and conversely, the area weight per unit area of ​​the highly absorbent polymer particles 56p in the lower layer 56b can be less than that in the lower layer 56a.

[0185] The ratio of pulp fibers 56f to highly absorbent polymer particles 56p in absorbent 56 is not particularly limited. For example, the weight ratio of pulp fibers 56f to highly absorbent polymer particles 56p can be 40:60 to 65:35.

[0186] The average particle size of the superabsorbent polymer particles 56p after swelling is preferably 2,000 to 3,000 μm, more preferably 2,200 to 2,800 μm. The average particle size of the superabsorbent polymer particles 56p after swelling refers to the average diameter of the particles in a swollen state after immersion in physiological saline for 60 minutes and followed by 15 minutes of dehydration. This average diameter is obtained by observing the swollen superabsorbent polymer particles 56p group from one direction at 50x magnification using a microscope, measuring the maximum diameter of any 20 particles appearing on the entire surface of the superabsorbent polymer particles 56p group, and taking the arithmetic mean. In particular, when the average particle size of the superabsorbent polymer particles 56p after swelling is greater than the average fiber length of the hardwood pulp fibers, the interweaving between the pulp fibers 56f is easily cut due to the expansion of the superabsorbent polymer particles 56p, thus making it difficult to hinder the expansion of the superabsorbent polymer particles 56p (making so-called gel blockage less likely), which is therefore preferable.

[0187] (Low weight per unit area)

[0188] Absorber 56 can be like Figures 1-4 As shown in the example, the crotch area M has elongated low-weight-per-unit-area portions 56L extending in the front-rear direction LD on both sides of the width direction WD. Although not shown, these low-weight-per-unit-area portions 56L may not be present. The low-weight-per-unit-area portion 56L refers to a portion with a lower weight per unit area, excluding portions like the high-compression portion 51 described later, which are compressed only along the thickness direction TD and have a constant weight per unit area. The low-weight-per-unit-area portion 56L can also be a slit extending in the thickness direction TD, but if it is a recess with a low aggregation of pulp fibers and highly absorbent polymer particles, as shown in the example, it is easier to ensure absorption, and therefore preferred. This recess can be formed on either the surface or the back side of the absorbent 56. By providing such a low-weight-per-unit-area portion 56L on the absorbent 56, the absorbent 56 is encouraged to bend along the low-weight-per-unit-area portion 56L, improving the fit of the absorbent 50 in the crotch area M. The total unit area weight of pulp fibers and superabsorbent polymer particles in the low unit area weight section 56L only needs to be less than the total unit area weight of pulp fibers and superabsorbent polymer particles in the parts other than the low unit area weight section 56L. For example, it can be 0.1 to 0.5 times the total unit area weight of pulp fibers and superabsorbent polymer particles in the parts other than the low unit area weight section 56L.

[0189] The low-weight-per-unit-area section 56L, being elongated and extending along the front-rear direction LD, can either extend linearly along the front-rear direction LD or bend laterally as shown in the example. Furthermore, the front and rear ends of the low-weight-per-unit-area section 56L can be appropriately shaped, for example, in addition to... Figure 12 Besides forming a straight line as shown in example (a), it can also be formed as follows: Figure 8 The example shown is formed into a curved, expanded shape (semi-circular arc, etc.). Although not illustrated, the corners at both ends can be rounded, making the middle part straight. The width m1 of the low unit area weight portion 56L can be appropriately determined, for example, it can be 0.04 to 0.1 times the width n1 of the narrowest part of the crotch portion M of the absorber 56 (meaning the full width 56X in the case of a rectangle). The width m1 of the low unit area weight portion 56L can be constant or varied in its length direction. The dimensions and arrangement of the front-to-back direction LD of the low unit area weight portion 56L can be appropriately determined. For example, the dimension m2 of the front-to-back direction LD of the low unit area weight portion 56L can be 50 to 120% of the dimension of the front-to-back direction LD of the crotch portion M, more preferably 50 to 80%. In addition, the low unit area weight portion 56L can be contained within the crotch portion M, or it can extend to the front, back, or front and back sides of the crotch portion M.

[0190] like Figure 8 As shown, a low-weight unit area section 56L is provided on each side of the crotch area M in the width direction WD, and another section is provided in the center of the width direction WD. Alternatively, it can be as follows: Figure 12 As shown in (a), only one is installed in the center, or as... Figure 12 As shown in (b), one is provided on each side of the width direction WD of the crotch M.

[0191] (High compression section)

[0192] In the absorber 50, such as Figure 3 , Figure 4 , Figures 9-11As shown, a plurality of high-compression portions 51 are spaced apart and compressed in the thickness direction TD such that they are recessed from the surface of the absorber 50 into the absorber 56. Furthermore, in the area where the plurality of high-compression portions 51 are arranged (a rectangular area formed by the edges along the front-rear direction LD and the width direction WD, respectively, and a rectangular area tangent to the entire high-compression portion 51), the portion other than the high-compression portions 51 becomes a non-high-compression portion 52 that is thicker and lower in density than the high-compression portions 51. The high-compression portions 51 are high-density portions with approximately equal thickness, compressed by pressing (direct pressure), and form the bottom of the recess. On the other hand, the non-high-compression portions 52 are thicker and lower in density than the high-compression portions 51, but even in the vicinity of the high-compression portions 51, the absorber 56 is deformed by the deformation and stretching of the high-compression portions 51, resulting in an increase in density as it approaches the high-compression portions 51. The non-high-compression portion 52, as long as it is thicker and has a lower density than the high-compression portion 51, can also be partially or completely compressed along the thickness direction TD simultaneously with, before or after the formation of the high-compression portion 51. Preferably, the non-high-compression portion 52 does not have recesses on either or both of the surface and back surfaces of the absorbent member 50.

[0193] In addition to being provided throughout the entire absorber 50 in both the front-rear and width directions (i.e., the entire surface of the absorber 50 becomes the arrangement area of ​​the high compression portion 51), the high compression portion 51 may also be provided only in a portion of the absorber 50 in the front-rear direction or a portion of the absorber 50 in the width direction. For example, although not shown, the high compression portion 51 may be provided only in the middle region of the front-rear direction LD including the crotch portion M, or conversely, the high compression portion 51 may not be provided in the middle region of the front-rear direction LD including the crotch portion M, but only in the regions on its front and rear sides. In addition, the high compression portion 51 in the illustrated example is not recessed from the surface of the sheet located on the surface of the absorber (top sheet 30 and middle sheet 40 in the illustrated example) into the absorber body 56, but is pressed in such a way that it can be recessed from the surface of the absorber 50 into the absorber body 56.

[0194] The density of the absorber 56 in the high-compression section 51 is not particularly limited, but is preferably 60,000 to 250,000 g / m³. 3 More preferably, it is 65,000~200,000 g / m 3 On the other hand, the density of the absorber 56 in the non-high-compression section 52 is not particularly limited, but is preferably 50,000 to 200,000 g / m³. 3 More preferably, it is 55,000~150,000 g / m 3 The density of the absorber 56 in the high-compression section 51 and the non-high-compression section 52 was determined by the following method.

[0195] (Method for measuring the density of absorber 56 in high-compression section 51)

[0196] (1) To expose the surface of the absorber 50 with a high compression portion 51, at least one sheet of the front and back sides of the absorber 50 is peeled off, and the area of ​​the high compression portion 51 is measured by the method described later.

[0197] (2) Measure the weight per unit area of ​​the absorber 50.

[0198] (3) Cut a portion of the packaging sheet 58 from the absorbent 50 and measure the weight per unit area of ​​the packaging sheet 58.

[0199] (4) Based on the measurement results of (1) and (2) above, the mass of the absorber 50 in the high compression section 51 is determined. Based on the measurement results of (1) and (3) above, the mass of the packaging sheet 58 in the high compression section 51 is determined. Subtracting the latter from the former, the mass of the absorber 56 in the high compression section 51 is determined.

[0200] (5) After freezing the absorber 50 with liquid nitrogen, cut it along the thickness direction TD in a way that crosses the approximate center of the high compression section 51, observe the cut surface with a microscope, and measure the thickness of the absorber 56.

[0201] (6) Assuming that the thickness of the absorber 56 in the high compression section 51 is constant, the volume of the absorber 56 in the high compression section 51 is obtained by multiplying the area of ​​the high compression section 51 in (1) above with the thickness of the absorber 56 in (5) above.

[0202] (7) By dividing (4) above by (6) above, the density of the absorber 56 in the high compression section 51 is obtained.

[0203] (Method for determining the density of absorbers in non-high compressibility regions)

[0204] (1) To expose the surface of the absorber 50 having the non-high compression portion 52, peel off at least one of the front and back sides of the absorber 50, and mark five rectangular measurement target areas of a predetermined size on the non-high compression portion 52 using a pen. Measure the size of the measurement target area and calculate the area.

[0205] (2) Measure the weight per unit area of ​​the absorber 50.

[0206] (3) Cut a portion of the packaging sheet 58 from the absorbent 50 and measure the weight per unit area of ​​the packaging sheet 58.

[0207] (4) Based on the measurement results of (1) and (2) above, calculate the mass of the absorber 50 in the measurement target area. Based on the measurement results of (1) and (3) above, calculate the mass of the packaging sheet 58 in the measurement target area. Subtract the latter from the former to calculate the mass of the absorber 56 in the measurement target area.

[0208] (5) After freezing the absorber 50 with liquid nitrogen, cut it along the thickness direction TD in a way that crosses the approximate center of the target area, observe the cut surface with a microscope, and measure the thickness of the absorber 56.

[0209] (6) Assuming that the thickness of the absorber 56 in the measurement target area is constant, the volume of the absorber 56 in the measurement target area is obtained by multiplying the area of ​​the measurement target area in (1) above with the thickness of the absorber 56 in (5) above.

[0210] (7) By dividing (4) above by (6) above, the density of the absorber 56 in the non-high compression section 52 is obtained.

[0211] Furthermore, the area of ​​each high-compression section 51 is not particularly limited, but is preferably 2 to 25 mm. 2 Left and right, with a preferred size of 3~15 mm. 2 .

[0212] The high-compression portion 51 is a high-density portion with approximately equal thickness, compressed along the thickness direction TD by pressing (direct pressure). It is the bottom of a recessed portion that is recessed from at least one side of the absorbent 50. This high-density portion has the property that the interlacing of fibers is difficult to break even when it swells due to liquid absorption. On the other hand, the non-high-compression portion 52 is a portion that is thicker and less dense than the high-compression portion 51. However, even in the vicinity of the high-compression portion 51, the absorbent 56 is deformed by the deformation and stretching of the high-compression portion 51. As a result, the density increases as it gets closer to the high-compression portion 51. Therefore, capillary action is strongly exhibited in the high-compression portion 51, resulting in not only higher liquid retention than the surrounding area, but also liquid being drawn towards the high-compression portion 51. Therefore, when the high-compression sections 51 are spaced apart and have a certain density and area, the strength of the absorber 56 containing broadleaf pulp fibers is difficult to decrease after liquid absorption. At the same time, the attraction force generated by the capillary phenomenon acts on more excreted liquid, and the excreted liquid absorbed by the absorber 56 diffuses more widely.

[0213] Although not illustrated, the high-compression portion 51 can be compressed along the thickness direction TD such that it is recessed into the absorbent body 56 from both the surface and back of the absorbent member 50, or it can be compressed along the thickness direction TD such that it is recessed into the absorbent body 56 only from the back of the absorbent member 50, in which case a recess is formed on the back of the absorbent member 50. However, as shown in the example, if the high-compression portion 51 is compressed along the thickness direction TD such that it is recessed into the absorbent body 56 from at least the surface of the absorbent member 50, both the backflow prevention and diffusion resistance are improved. That is, as described above, in the high-compression portion 51, the capillary effect is strongly manifested, not only is the liquid retention higher than the surrounding area, but the liquid is not only drawn towards the high-compression portion 51, but the excreted liquid collected by the high-compression portion 51 can also be strongly held away from the skin. As a result, backflow is difficult to occur.

[0214] Furthermore, the shortest distance d4 between the other highly compressible portions 51 that are closest to each other can be about 1 to 4 mm, more preferably about 1.5 to 3.5 mm. In this way, when the highly compressible portions 51 are arranged at relatively close intervals, the strength of the absorbent body 56 after liquid absorption is less likely to decrease, and the attraction force generated by the capillary phenomenon acts on more excreted liquid, and the excreted liquid absorbed by the absorbent body 56 diffuses more widely. In addition, when the highly compressible portions 51 with a certain area are arranged at such intervals, the distance between the pulp fibers 56f in the highly compressible portions 51 shrinks, thereby strengthening the entanglement of the pulp fibers 56f, reducing the gaps between the pulp fibers 56f that serve as the movement path of the highly absorbent polymer particles 56p, and increasing the contact portion between the pulp fibers 56f and the highly absorbent polymer particles 56p. As a result, the movement of the highly absorbent polymer particles 56p within the absorbent body 56 and the movement of the highly absorbent polymer particles 56p outside the absorbent body 56 can be suppressed. That is, the retention of highly absorbent polymer particles 56p in the absorbent 56 containing broadleaf pulp fibers is improved.

[0215] The area ratio of the high-compression portions 51 in the arrangement region of the high-compression portions 51 (the total area of ​​the high-compression portions 51 / the area of ​​the arrangement region of the high-compression portions 51) is preferably 10-35%, more preferably 20-35%. Furthermore, the diameter of the largest inscribed circle 54 tangent to the outer shape of the non-high-compression portions 52 is preferably 30 mm or less, more preferably 10 mm or less, more preferably 6.5 mm or less, even more preferably 6 mm or less, and particularly preferably 5 mm or less. Moreover, the lower limit of the diameter of the largest inscribed circle 54 tangent to the outer shape of the non-high-compression portions 52 is preferably 2 mm, more preferably 3 mm, and particularly preferably 4 mm.

[0216] Thus, by arranging the high-compression portions 51 particularly densely, the aforementioned liquid diffusivity can be further improved. Furthermore, the retention of the highly absorbent polymer particles 56p is further improved. Moreover, even in the vicinity of the high-compression portions 51 in the non-high-compression portions 52, the absorber 56 is deformed by the stretching caused by the high-compression portions 51, resulting in a thinner absorber 56 compared to the case without high-compression portions 51. From these viewpoints, it is particularly preferable that the area ratio of the high-compression portions 51 is within the aforementioned range. Furthermore, to prevent the arrangement of the high-compression portions 51 from being sparse (so that the non-high-compression portions 52 do not remain long in all directions), it is particularly preferable that the diameter of the largest inscribed circle 54 tangent to the outer shape of the non-high-compression portions 52 is small.

[0217] The size and shape of the high-compression portion 51 can be appropriately determined. However, since the high-compression portion 51 is a rigid part, if the size of the high-compression portion 51 is too large, or the shape of the high-compression portion 51 is too long in one direction, or has an excessively interlaced shape, the overall softness of the absorbent body 56 may be insufficient, and a foreign body-like sensation (foreign body feeling) may occur within the absorbent body 56. In addition, if the size of the high-compression portion 51 is too small, or the shape of the high-compression portion 51 is too long in one direction, or has an excessively interlaced shape, the packaging sheet 58 may easily break if it is made of crepe paper. Therefore, the diameter of the largest inscribed circle 53 tangent to the shape of the high-compression portion 51 is preferably 1 to 10 mm, more preferably 1 to 6 mm, further preferably 2 to 5 mm, and more preferably 2.5 to 3.5 mm. Furthermore, the perimeter of the high compression portion 51 is preferably 1 to 15 times the perimeter of the largest inscribed circle 53 that is inscribed in the perimeter of the high compression portion 51, more preferably 1 to 5 times, even more preferably 1.0 to 2.5 times, even more preferably 1.0 to 2.0 times, and particularly preferably 1.0 to 1.6 times.

[0218] As an example, the major axis d1 (the length of the long side of the smallest circumscribed rectangle) of each high compression section 51 can be about 4 to 9 mm, and the minor axis d2 (the length of the short side of the smallest circumscribed rectangle) can be about 2 to 5 mm. When the lengths of the four sides of the smallest circumscribed rectangle of each high compression section 51 are equal, the length d3 of that side can be about 2 to 5 mm.

[0219] The shortest dimension of each high-compression portion 51 is not particularly limited, but it is preferably longer than the average fiber length of the hardwood pulp fiber, more preferably 4 times or more, further preferably 4 to 10 times, and particularly preferably 4 to 12 times. If the shortest dimension of each high-compression portion 51 is longer than the average fiber length of the hardwood pulp fiber, the uneven distribution of the pulp is reduced, which has the advantage of improving the shape maintenance of the absorbent. In addition, the shortest dimension of each high-compression portion 51 is preferably longer than the average particle size of the highly absorbent polymer particles 56p after swelling, more preferably 1.5 times or more, further preferably 1.5 to 6 times, and particularly preferably 1.5 to 5 times. If the shortest dimension of each high-compression portion 51 is longer than the average particle size of the highly absorbent polymer particles 56p after swelling, it has the advantages of improved retention of the highly absorbent polymer particles and reduced uneven distribution of absorption performance.

[0220] The shape of the high-compression section 51 is not particularly limited. It is preferred to be a circle, an ellipse, or a rounded rectangle (including shapes where the opposite sides of any one side are not straight lines but are semicircles), without inflection points or bending points. However, it can also be a triangle, a quadrilateral, a cloud shape, an X shape, a V shape, a U shape, etc.

[0221] Generally, to improve backflow prevention, the mixing ratio of highly absorbent polymer particles with high liquid retention is increased. Furthermore, in recent years, to achieve purposes such as thinning the absorbent body 56, the mixing ratio of highly absorbent polymer particles has also been frequently increased. However, increasing the mixing ratio of highly absorbent polymer particles not only reduces the shape retention of the high-compression section 51, but also makes it difficult for the absorbent body 56 to be deformed by the stretching of the high-compression section 51 around the non-high-compression section 52, potentially hindering the improvement of low backflow and diffusion properties. Additionally, the highly absorbent polymer particles, due to their expansion from absorbing the discharged liquid, are closely packed together, easily causing a phenomenon that hinders the diffusion of the discharged liquid (gel blockage), thus potentially hindering the improvement of diffusion properties. Therefore, the area weight of the pulp fibers in the absorbent body 56 is 100~500 g / m². 2 In this case, the pulp fiber to highly absorbent polymer particles in the absorbent 56 are preferably in a weight ratio of 45:55 to 65:35.

[0222] The thickness 50t of the absorbent 50 and the thickness 51t of the high-compression section 51 can be appropriately determined, but if the compression is insufficient, it may be difficult to improve the low backflow and diffusion properties. Therefore, when using the above-mentioned range of the unit area weight of pulp fibers and the range of the ratio of pulp fibers to highly absorbent polymer particles, the thickness 50t of the absorbent 50 (the thickness of the non-high-compression section 52) is preferably 3 to 13 mm. At this time, the thickness 51t of the high-compression section 51 (the minimum value when the thickness varies) can be appropriately determined, but in general, it is preferably 60 to 90% of the thickness 50t of the absorbent 50.

[0223] The high-compression section 51 can be arranged in a suitable regular or irregular pattern. For example, the high-compression section 51 can be exemplified as follows: Figure 17 The high-pressure sections 51, arranged in a grid pattern, are shown as dotted lines, or as... Figure 18 and Figure 19 The dotted high-pressure portions 51 shown are arranged in a houndstooth and matrix pattern, as well as... Figure 20 The X-shaped high-compression portions 51 shown are arranged in a matrix or similar pattern. Alternatively, although not shown, the high-compression portions could be arranged in a grid pattern of continuous straight lines, or in a pattern where high-compression portions of different sizes or shapes are spaced apart to represent a predetermined pattern. In particular, when the high-compression portions 51 are arranged in a dotted-line pattern or in a grid pattern of continuous straight lines, the movement of the highly absorbent polymer particles 56p in the non-high-compression portions 52 is suppressed within the area surrounded by the high-compression portions 51, thus suppressing the uneven distribution of the highly absorbent polymer particles 56p with fewer high-compression portions 51. For example, it could also be as follows... Figure 21 The pattern shown is such that multiple high-compression sections 51 with different areas are arranged, and the area of ​​the largest high-compression section 51 is more than three times the area of ​​the smallest high-compression section 51. Figure 21 The pattern shown has multiple linear high-compression sections 51 of varying lengths but the same width, with the longest high-compression section 51 being more than three times the length of the shortest high-compression section 51. Furthermore, in Figure 21 In the example pattern shown, a high-compression portion 51 extending in the front-to-back direction LD, a high-compression portion 51 extending obliquely, and a high-compression portion 51 formed by a portion extending in the front-to-back direction LD and a portion extending obliquely from its front and rear ends are arranged in combination. Furthermore, in Figures 17-21 The dimensions of each part are recorded, but these dimensions are only examples and can of course be changed appropriately.

[0224] A preferred pattern for the high-compression section 51 is Figure 11 and Figure 16The example shown. In this example, in the arrangement area of ​​the high compression section 51, an imaginary grid is defined. This imaginary grid is formed by repeatedly arranging a first imaginary straight line 81 along a first direction at a first interval 81d spaced apart in a second direction at a clockwise inclination of 80-90° relative to the first imaginary straight line 81 when viewed from above, and repeatedly arranging a second imaginary straight line 82 along the second direction at a second interval 82d spaced apart in the first direction. Furthermore, when the smallest imaginary quadrilateral 83 with the intersection of the first imaginary straight line 81 and the second imaginary straight line 82 as its vertex is determined, the high compression section 51 includes: a first high compression section 51a, which is arranged at the intersection of the first imaginary straight line 81 and the second imaginary straight line 82; a second high compression section 51b, which is arranged between adjacent first high compression sections 51a on the first imaginary straight line 81 and between adjacent first high compression sections 51a on the second imaginary straight line 82; and a third high compression section 51c, which is arranged at the intersection of the diagonals of the imaginary quadrilateral. Furthermore, the first high-compression section 51a is a circle centered at the intersection of the first imaginary line 81 and the second imaginary line 82; the second high-compression section 51b is a rectangle (or an ellipse) with a center of gravity at the midpoint of each side of the imaginary quadrilateral and having rounded corners along the major axis of each side; and the third high-compression section 51c is a rectangle (or an ellipse, or a circle centered at the intersection of the diagonals of the imaginary quadrilateral) with a center of gravity at the intersection of the diagonals of the imaginary quadrilateral and having a square-rounded rectangle (or an ellipse, or a circle centered at the intersection of the diagonals of the imaginary quadrilateral) along the major axis direction LD. This pattern improves the diffusion of the second high-compression section 51b in the major axis direction (both the first and second directions). Simultaneously, because it has both a portion that is not a straight line continuous with the high-compression section 52 in the first direction and a portion that is not a straight line continuous with the high-compression section 52 in the second direction, even if each high-compression section 51 hardens, the absorber 56 as a whole can easily deform along the body surface.

[0225] When along Figure 11 and Figure 16 In the hypothetical grid arrangement of the high-compression sections 51 shown in the example, the dimensions of each high-compression section 51 can be appropriately determined. However, the diameter of the first high-compression section 51a is 1-4 mm, the length of the major axis of the second high-compression section 51b is 3-6 mm, and the length of the minor axis is equal to the diameter of the first high-compression section 51a. The third high-compression section 51c has the same size and shape as the second high-compression section 51b, except that the orientation of its major axis is along the front-rear direction LD. If the shortest distance d4 between adjacent first high-compression sections 51a and second high-compression sections 51b is 1-2 mm, it not only improves the backflow prevention and liquid diffusion properties but also improves the deformability of the absorbent 56, which is therefore preferred. The ratio of the first interval 81d to the second interval 82d is preferably in the range of 0.9:1.1 to 1.1:0.9, and it is particularly preferred that the first interval 81d and the second interval 82d are equal. The first interval 81d and the second interval 82d can be about 10-14 mm.

[0226] Furthermore, if the aforementioned imaginary grid is formed as an inclined grid with the first imaginary straight line 81 tilted 40-50° clockwise relative to the front-back direction LD when viewed from above, and the second imaginary straight line 82 tilted 40-50° counterclockwise relative to the front-back direction LD when viewed from above, then the deformability of the absorbent body 56 when worn goes without saying, and the diffusion of the liquid is also excellent, so it is preferred.

[0227] The specific arrangement of the high-compression section 51 is shown in Table 2.

[0228] [Table 2]

[0229]

[0230] The absorbent element can be manufactured by known methods. For example, the absorbent element 50 having a high-compression portion 51 can be manufactured by performing the following steps: First step, forming an absorbent body 56 by mixing and agglomerating pulp fibers and highly absorbent polymer particles; Second step, forming a package 50P by packaging the absorbent body 56 as a whole with a packaging sheet 58; Third step, as... Figure 22 As shown, the package 50P is passed between an anvil roller 90 and a smoothing roller 92. The anvil roller 90 has a plurality of protrusions 91 arranged at intervals on its outer circumferential surface with the same pattern as the high-compression section 51. The smoothing roller 92 has a cylindrical surface opposite to it (without protrusions 91). The high-compression section 51 is formed by pressing the portion of the package 50P sandwiched between the plurality of protrusions 91 of the anvil roller 90 and the smoothing roller 92. The high-compression section 51 can be formed while heating either or both of the anvil roller 90 and the smoothing roller 92, or it can be formed without heating. In the third step, only the portion of the package 50P sandwiched between the plurality of protrusions 91 of the anvil roller 90 and the smoothing roller 92 can be pressed, or the entire package 50P can be pressed while pressing the portion of the anvil roller 90 sandwiched between the plurality of protrusions 91 and the smoothing roller 92 to its deepest point.

[0231] The dimensions, shape, and arrangement of the front end face of the protrusion 91 can, for example, be the same as those of the high compression portion 51. The gap between the anvil roller 90 and the smoothing roller 92 (the minimum interval of the pressing position) can be set to be less than or equal to the thickness of the high compression portion 51; for example, it can be set to 0.5 to 1.5 mm. The pressure at which the high compression portion 51 is formed by the anvil roller 90 and the smoothing roller 92 can be appropriately set, but for example, it can be set to 0.2 to 0.4 MPa.

[0232] (Packaging film)

[0233] As the packaging sheet 58, liquid-permeable sheets such as crepe paper, nonwoven fabric, polyamide nonwoven fabric, and perforated sheets can be used. There are no particular limitations on the nonwoven fabric used for the packaging sheet 58; SMS nonwoven fabric or SSMMS nonwoven fabric with at least one meltblown layer sandwiched between a pair of spunbond layers on the front and back is preferred. There are no particular limitations on the fiber material; for example, polypropylene fibers or polyethylene / polypropylene bicomponent fibers can be used. The area weight per unit area of ​​the packaging sheet 58 can be appropriately determined, but ideally it should be 5~40 g / m². 2 Ideally, the concentration should be 10-30 g / m³. 2 .

[0234] There are no specific limitations on the crepe paper used in packaging sheets, but the ideal weight per unit area is 13~20 g / m². 2 Ideally, the concentration should be 14-18 g / m³. 2 In addition, according to JISP8117:2009 "Paper and paperboard - Test methods for air permeability and air resistance (middle zone) - Gurley method" for crepe paper, the ideal air permeability is 1 to 15 seconds.

[0235] The average fiber length of the pulp constituting the crepe paper for packaging sheet 58 can be less than twice the average fiber length of all pulp fibers constituting absorber 56, but if it is 1.5 to 3 times, it has the advantage of improving material strength, and is therefore preferred. It is more preferable when the average fiber length of the pulp constituting the crepe paper for packaging sheet 58 is 1.5 to 3 times the average fiber length of all pulp fibers constituting absorber 56.

[0236] On the other hand, the crepe paper used for the packaging sheet 58 typically has a tensile elongation at break of 20-35% in the longitudinal direction (LD) and a tensile elongation at break of 4-8% (especially 5-7%) in the width direction (WD) as specified in JISP 8113:2006. If the packaging sheet 58 is such crepe paper, the crepe paper may sometimes break at the edge of the high compression portion 51 or between adjacent high compression portions 51 when the high compression portion 51 is formed. However, this can be reduced by making the shape of the high compression portion 51 without inflection points or bends, having a diameter of the largest inscribed circle tangent to the shape of the high compression portion 51 of 2-5 mm, and having a perimeter of the shape of the high compression portion 51 of 1-2.5 times the perimeter of the largest inscribed circle tangent to the shape of the high compression portion 51.

[0237] If the MD direction of the packaging sheet 58 is formed along the front-to-back LD direction, manufacturing is easier, and this is preferred. In this case, since the fiber orientation of the packaging sheet 58 is in the front-to-back LD direction, the dry tensile strength in the width direction WD is significantly weaker than the dry tensile strength in the front-to-back LD direction. Therefore, if the dimension of the front-to-back LD direction of the high-compression portion 51 is more than twice, especially more than three times, the dimension of the width direction WD of the high-compression portion 51 (i.e., the high-compression portion 51 has a longer shape in the front-to-back LD direction), the packaging sheet 58 is prone to breakage on both sides of its width direction WD. Therefore, if the dimension of the front-to-back LD direction of the high-compression portion 51 is less than twice, especially less than 1.5 times, the packaging sheet 58 is less likely to break, and this is preferred.

[0238] The packaging structure of the packaging sheet 58 can be appropriately determined, but from the viewpoint of ease of manufacturing or preventing highly absorbent polymer particles from leaking out from the front and rear ends, as shown in the example, it is rolled into a cylindrical shape to surround the front and back sides and both sides of the absorber 56, and its front and rear edges extend from the front and rear of the absorber 56. It is preferable to join the overlapping parts of the rolled part and the front and rear extended parts by joining methods such as hot melt adhesive or material welding.

[0239] In particular, such as Figure 15 As shown, the packaging sheet 58 has: a surface portion 58s located on the surface of the absorber 56; a first back side portion 58a that extends from the surface portion 58s, wraps around one side edge of the absorber 56, and reaches the back side of the absorber 56; and a second back side portion 58b that extends from the surface portion 58s, wraps around the other side edge of the absorber 56, and reaches the back side of the absorber 56. The first back side portion 58a and the second back side portion 58b have overlapping laminated portions 58W. If all the high-compression portions 51 are formed on the laminated portions 58W, the crepe paper on the forming surface of the high-compression portions 51 becomes double, the strength is increased, and it is difficult to break when forming the high-compression portions 51, which is therefore preferred.

[0240] The shape retention of the high-compression portion 51 on the absorbent 50 is influenced by the shape retention of the high-compression portion 51 itself, which in turn is influenced by the bonding strength between the packaging sheet 58 of the high-compression portion 51 and the absorbent 56, or by the shape retention of the absorbent 56 itself. Furthermore, when using hot-melt adhesives HM1 and HM2 to bond the packaging sheet 58 to the absorbent 56, the increased surface area due to the formation of the high-compression portion 51 necessitates a greater amount of hot-melt adhesive HM1 and HM2 than usual to adequately maintain the bonding strength between the packaging sheet 58 and the absorbent 56, and the shape retention of the absorbent 56 itself. Therefore, the surface of the absorbent 56 and the inner surface of the packaging sheet 58 preferably have a surface area of ​​5.0~20.0 g / m². 2Especially 7.5~15.0 g / m 2 Hot melt adhesives HM1 and HM2 are used for bonding.

[0241] For example, such as Figure 9 As shown, when a depression caused by the high-compression portion 51 is formed on the surface of the absorber 56, by providing two layers of hot-melt adhesive HM1 and HM2 on the back side of the absorber 56 throughout the entire area having the high-compression portion 51, the amount of the aforementioned hot-melt adhesive HM can be achieved. Figure 13 As shown, after applying a first hot melt adhesive HM1 to the inner surface of the unfolded packaging sheet 58 on approximately the entire surface opposite to the absorber 56, the absorber 56 is arranged at the middle portion of the width direction WD of the first hot melt adhesive HM1 on the packaging sheet 58. The back side of the absorber 56 and the packaging sheet 58 are bonded by the first hot melt adhesive HM1. Then, after applying a second hot melt adhesive HM2 to approximately the entire surface of the absorber 56, as shown... Figure 14 As shown, the portions of the packaging sheet 58 extending to both sides of the absorber 56 are folded back onto the surface of the absorber 56. The surface of the absorber 56 and the folded portions of the packaging sheet 58 are bonded together using a first hot melt adhesive HM1 and a second hot melt adhesive HM2. Simultaneously, the overlapping portions of the packaging sheet 58 are bonded together using the first hot melt adhesive HM1. Then, as... Figure 9 As shown, this structure is manufactured by forming a grid-shaped high-compression section 51 through embossing.

[0242] In order to reduce costs, such as Figure 9 As shown, the absorbent 50 may not have any other sheets such as paper or nonwoven fabric between the packaging sheet 58 and the absorbent 56 (or may have an adhesive layer), or may have other sheets on at least one side of the surface or back of the absorbent 56.

[0243] <Manufacturing Method of Absorber>

[0244] Absorber 56 can be manufactured using known methods. Figure 25 This is a schematic diagram illustrating an example of an absorbent manufacturing apparatus 100. In this absorbent manufacturing apparatus, an upstream pulp supply section 111 is provided for supplying fibrous material mainly comprising pulp. The pulp supply section 111 may include a desplitter for supplying pulp sheets 110 therein.

[0245] In manufacturing an absorber 56 containing hardwood pulp fibers, pulp sheets 110 containing hardwood pulp fibers are fed to a defiberizer. In the defiberizer, the pulp sheets 110 are mechanically defibered into fibers to obtain fluff pulp. The pulp sheets 110 can be either in bundles or rolls, but rolls are preferred as they increase productivity.

[0246] Furthermore, there are no particular limitations on the apparatus used for the mechanical processing of defibering the pulp sheet 110. Known defibering machines used in the manufacture of absorbent articles such as disposable diapers can be used. As for the mechanical processing, defibering machines utilizing friction or shear force are preferred. Examples of defibering machines include, for example, hammer defibering machines, impact defibering machines, roller defibering machines, and jet airflow defibering machines.

[0247] The fluff pulp obtained from fiber debonding is supplied into pipe 112. A polymer particle inlet 113 for supplying superabsorbent polymer particles can be provided midway through pipe 112. Therefore, pulp fibers 56f (fluff pulp) and superabsorbent polymer particles 56p are mixed in pipe 112 and then supplied to fiber stacking roller 115. Multiple absorber molds 115C are arranged circumferentially on the outer circumferential surface of fiber stacking roller 115. When fiber stacking roller 115 rotates, absorber molds 115C can sequentially receive the mixture of pulp fibers 56f and superabsorbent polymer particles 56p. The bottom surface of absorber mold 115C is composed of a perforated plate or mesh plate, and by drawing gas through the openings, the mixture of pulp fibers and superabsorbent polymer particles can be collected on the bottom surface of absorber mold 115C. Furthermore, by discharging gas through the openings, absorbers 56 can be supplied to conveying units 116 such as belt conveyors. Inside the fiber stacking roller 115, there are negative pressure chambers and positive pressure chambers, which allow for the suction and discharge of gas.

[0248] A scraping roller (or brush) 114 can be positioned downstream within the conduit 112. The scraping roller 114 scrapes away excess absorbent material accumulated after fiber buildup, homogenizing the surface of the absorbent material gathered in the absorbent mold 115C. Furthermore, the absorbent 56 supplied to the conveying unit 116 can be compressed in the thickness direction by the compression unit 117. For example... Figure 25 As shown, the compression unit 117 can be a pair of rollers or a pair of pressing members approaching from both sides of the absorber 56. The compression unit 117 improves the shape retention of the absorber 56.

[0249] Further downstream, absorbent 56 becomes absorbent element 50 by being wrapped by packaging sheet 58. The process of wrapping absorbent 56 with packaging sheet 58 can also be carried out by known methods.

[0250] When two layers of absorber 56 are stacked, as follows: Figure 26 As shown, a manufacturing apparatus 120 can be used, comprising single-layer manufacturing units 101 and 102 for manufacturing the layers of the absorber 56, which are shown as upper layer 56a and lower layer 56b in the example. The single-layer manufacturing units 101 and 102 each have the same features as the manufacturing apparatus 100 for manufacturing single-layer absorbers. Figure 25The same structure. The layers 56a and 56b of the absorbent, which are manufactured in the single-layer manufacturing sections 101 and 102 respectively, are overlapped in the thickness direction and then wrapped with the packaging sheet 58 to form an absorbent.

[0251] (Stand up the pleats)

[0252] The stand-up pleats 60 have stand-up portions 68 that rise from the side of the inner body 200. These stand-up portions 68 contact the area from the wearer's groin, through the leg opening, to the buttocks to prevent side leakage. The stand-up pleats 60 can also be omitted if necessary. The stand-up pleats 60 in the illustration are structured such that the root side portion 60B is inclined towards the center of the width direction, while the front side portion 60A is inclined towards the outer side of the width direction compared to the middle portion. However, this is not a limitation, and appropriate modifications can be made, such as having the pleats rise towards the center of the width direction as a whole.

[0253] More specifically, the stand-up pleats 60 in the example figure are formed by folding a strip-shaped pleated piece 62, which has a length equal to that of the inner body 200 in the front-to-back direction, back into a double layer at the front end portion along the width direction WD. Between this folded portion and its adjacent pieces, multiple elongated pleat elastic members 63 are fixed at intervals along the width direction WD in an elongated state. The base end portion of the stand-up pleat 60 located on the side opposite to the front end portion (the end opposite to the folded portion in the width direction WD) is designated as a root portion 65 fixed to the side of the inner body 200. The portion other than the root portion 65 is the main body portion 66 (the portion on the folded portion side) extending from the root portion 65. Furthermore, the main body portion 66 has a root side portion 60B extending towards the center in the width direction and a front side portion 60A folded back at the front end of the root side portion 60B and extending outward in the width direction. Furthermore, the two ends of the main body 66 in the front and rear directions are set as folded portions 67 fixed relative to the side surface of the top plate 30 in a folded state. On the other hand, the middle part in the front and rear directions between them is set as an unfixed upright portion 68. At least the front end of the upright portion 68 is fixed with a pleated elastic member 63 in the front and rear directions LD in an extended state.

[0254] In the raised pleats 60 constructed as described above, the raised portion 68 is raised as follows, utilizing the contraction force of the pleat elastic member 63. Figure 3 The center arrow indicates that the pleats 60 are raised in contact with the skin. Specifically, when the root portion 65 is located on the back side of the inner body 200, the raised portion 68 in and around the crotch opens outwards in the width direction, thus raising the pleats 60 so that they face against the leg, improving fit. The root portion 65 can also be fixed to the front side of the inner body 200, for example, to the surfaces of both sides of the top piece 30.

[0255] As illustrated in the example of the raised pleats 60, in the curved structure of the main body 66, which consists of a root side portion 60B extending towards the center in the width direction and a front end side portion 60A folded back at the front end of the root side portion 60B and extending outward in the width direction, the front end side portion 60A and the root side portion 60B are joined in a folded state by the folded portion 67, and the root side portion 60B is joined to the top piece 30 in a folded state. In the joining of the opposing surfaces of the folded portions 67, at least one of the following methods can be used: hot melt adhesive using various coating methods, and material welding methods such as heat sealing or ultrasonic sealing. In this case, the joining of the root side portion 60B and the top piece 30, and the joining of the front end side portion 60A and the root side portion 60B, can be performed using the same method or different methods. For example, it is preferable to use a hot melt adhesive to join the root side portion 60B and the top piece 30, and to join the front end side portion 60A and the root side portion 60B by material welding.

[0256] As the pleat sheet 62, it is preferable to use a material that has undergone water-repellent treatment with silicone or the like on a soft and uniform nonwoven fabric such as spunbond nonwoven fabric (SS, SSS, etc.) or SMS nonwoven fabric (SMS, SSMMS, etc.), meltblown nonwoven fabric, etc., as needed. In this case, the fiber area weight of the nonwoven fabric is preferably 10~30 g / m². 2 Additionally, although not shown, a waterproof membrane may be sandwiched between the double-layered pleats 62.

[0257] Rubber thread or the like can be used as the pleated elastic member 63. When using spandex elastic thread, its fineness is preferably 470~1240 dtex, more preferably 620~940 dtex. The elongation of the pleated elastic member 63 in the installed state is preferably 150~350%, more preferably 200~300%. The number of pleated elastic members 63 is preferably 2~6, more preferably 3~5. An arrangement interval of 3~10 mm for the pleated elastic members 63 is suitable. With this configuration, it is easy to make surface contact with the skin within the area where the pleated elastic members 63 are arranged. The pleated elastic members 63 can be arranged not only on the front end side but also on the root side.

[0258] In the erected portion 68 of the erected pleat 60, the bonding of the inner and outer layers of the pleat piece 62 and the fixation of the pleat elastic member 63 sandwiched therebetween can be at least one of the following fixing methods: hot melt adhesive using various coating methods and fixing by material welding such as heat sealing or ultrasonic sealing. If the entire surface of the inner and outer layers of the pleat piece 62 is bonded together, the flexibility will be compromised. Therefore, the portion of the pleat elastic member 63 other than the bonding portion is preferably not bonded or weakly bonded. The diagram illustrates the following structure: hot melt adhesive is applied only to the outer peripheral surface of the pleated elastic member 63 using a coating mechanism such as a coating gun or a Sure Wrap adhesive nozzle, and sandwiched between the inner and outer layers of the pleated sheet 62. Thus, the pleated elastic member 63 is fixed to the inner and outer layers of the pleated sheet 62, and the pleated sheet 62 is fixed between the inner and outer layers, solely by the hot melt adhesive applied to the outer peripheral surface of the pleated elastic member 63.

[0259] Similarly, for fixing the collapsed portion 67, at least one of the following methods can be used: hot melt adhesive using various coating methods, and heat sealing or ultrasonic sealing, which utilize material welding.

[0260] (flank)

[0261] like Figures 1-4 As shown, side wings 70 extending laterally toward the absorber 56 are provided on both sides of the inner body 200, and preferably, a lateral stretching region SG that stretches in the front-rear direction is formed on the side wings 70. The side wing 70 in the example figure has: one or more elongated lateral elastic members 73 arranged at intervals along the front-rear direction LD; a first layer 71 facing the outer side of the lateral elastic members 73; and a second layer 72 facing the inner side of the lateral elastic members 73.

[0262] The sheet material constituting the first layer 71 and the second layer 72 is not particularly limited, and can be any suitable nonwoven fabric, such as the nonwoven fabric available in the aforementioned raised pleats 60 or the aforementioned outer casings 12F and 12B. In the illustrated example, as described later, the pleat piece 62 of the raised pleats 60 is extended to form the first layer 71 and the second layer 72. At this time, the front and rear ends of the side wings 70 are raised, aligning with the front and rear ends of the pleats 60 (i.e., in this case, the front and rear ends of the inner casing 200).

[0263] The side elastic member 73 is not particularly limited, and the same elongated elastic member as the pleated elastic member 63 described above can be used. The elongation of the side elastic member 73 in the installed state is preferably 150-350%, more preferably 200-270%. The number of side elastic members 73 is preferably 2-16, more preferably 6-10. An arrangement interval of 5-10 mm for the side elastic members 73 is suitable.

[0264] The side elastic member 73 is fixed to the first layer 71 and the second layer 72. For the fixation of the side elastic member 73, which is bonded between the first layer 71 and the second layer 72, various methods of material welding can be used, such as hot melt adhesive HM based on different coating methods, heat sealing, or ultrasonic sealing. If the joint area between the first layer 71 and the second layer 72 is large, it will impair flexibility; therefore, it is preferable that the portion of the side elastic member 73 other than the adhesive portion is not joined or is weakly joined. The illustrated example shows the following structure: by applying hot melt adhesive HM only to the outer peripheral surface of the side elastic member 73 using a coating mechanism such as a coating gun or a Sure Wrap adhesive nozzle, and sandwiching it between the first layer 71 and the second layer 72, the side elastic member 73 is fixed to the first layer 71 and the second layer 72, and the fixation between the first layer 71 and the second layer 72, using only the hot melt adhesive HM applied to the outer peripheral surface of the side elastic member 73.

[0265] Additionally, in the example shown, the sheet forming the first layer 71 and the sheet forming the second layer 72 are folded back at the side edge of the side wing 70, and this folded portion is fixed to the back of the liquid-impermeable sheet 11 (bag closed). This fixing can be achieved not only using hot melt adhesive HM as shown in the example, but also by welding the materials together.

[0266] The 70 flank can also be omitted.

[0267] <Example of manufacturing pulp sheets for absorbent manufacturing>

[0268] Using the materials shown in Table 1, produce pulp sheets No. 1 to 20 containing hardwood pulp fibers according to the following process.

[0269] (Steaming / cooking process)

[0270] (1) Broad-leaved tree

[0271] Locust wood and eucalyptus wood were mixed according to the mass ratio recorded in Table 1, and white liquor with a specified degree of sulfidation was added. The mixture was then cooked in a rotary autoclave at a liquor ratio of 6.0 (L / kg) and a maximum temperature of 170°C to obtain unbleached kraft pulp of broadleaf trees with a kappa number of approximately 16.

[0272] (2) Conifers

[0273] Add white liquor with a specified degree of sulfidation to the fir, and cook it in a rotary autoclave at a liquor ratio of 6.0 (L / kg) and a maximum temperature of 170°C to obtain unbleached coniferous kraft pulp with a kappa number of about 30.

[0274] (Cleaning process)

[0275] After diluting the unbleached pulp to a pulp concentration of approximately 2%, No. 2 filter paper (manufactured by ADVANTEC) is placed on a Buchner funnel to dewater the pulp to a concentration of approximately 12%. Then, the unbleached pulp is sandwiched between square filter paper (manufactured by ADVANTEC) and pressure is applied using a press to dewater it to a pulp concentration of 33%. This washing process is performed twice.

[0276] (Bleaching process)

[0277] (1) Broad-leaved tree

[0278] Unbleached kraft pulp was ozone bleached for approximately 2 minutes at 45°C using 8.1% ozone gas. The ozone bleaching was performed using ozone gas from a laboratory ozone generator (PSA Ozonizer SGA-01A-PSA4) manufactured by Sumitomo Precision Industries. Subsequently, the ozone-bleached pulp was bleached with chlorine dioxide at a chlorine dioxide addition rate of 1.5%, a pulp concentration of 10% by mass, and at 70°C to obtain bleached hardwood kraft pulp. Between each bleaching step, after diluting the pulp to approximately 2% concentration, No. 2 filter paper (manufactured by ADVANTEC) was placed on a Buchner funnel, and two dilution washing processes were performed to dehydrate the pulp to approximately 12% concentration.

[0279] (2) Conifers

[0280] Unbleached kraft pulp was bleached with chlorine dioxide for 30 minutes at 70°C with a chlorine dioxide addition rate of 1.5% and a pulp concentration of 10% by mass. Next, it was bleached with alkaline hydrogen peroxide for 120 minutes at 70°C with an alkali addition rate of 1% and a hydrogen peroxide addition rate of 0.3% and a pulp concentration of 10% by mass. Then, it was alkali-treated for 120 minutes at 70°C with a sodium hydroxide addition rate of 0.2% and a pulp concentration of 10% by mass. Finally, it was bleached with chlorine dioxide for 150 minutes at 70°C with a chlorine dioxide addition rate of 0.3% and a pulp concentration of 10% by mass to obtain bleached coniferous kraft pulp. Between each bleaching step, after diluting to approximately 2% pulp concentration, No. 2 filter paper (manufactured by ADVANTEC) was placed on a Buchner funnel, and two dilution washing processes were performed to dehydrate the pulp to approximately 12% pulp concentration.

[0281] (Papermaking process)

[0282] The prepared bleached kraft pulp from broadleaf trees and bleached kraft pulp from coniferous trees were diluted to a concentration of approximately 2% without beating, and adjusted to the ratios shown in Table 2. Then, using the adjusted pulp, hand-made paper sheets (for fluff pulp) with a basis weight of 800 g / m² were produced by a semi-automatic sheet-making machine (manufactured by Kumagai Riki Kogyo Co., Ltd.).

[0283] <Crafting Absorbent Items>

[0284] Using each pulp sheet, through Figure 25 The apparatus shown is used to manufacture absorbents. The amount of highly absorbent polymer added to the fluff pulp is 9.3 g relative to 7.7 g of fluff pulp. Using the resulting absorbent, without the aforementioned high-compression section 51, disposable diapers (belt type, L size) are manufactured.

[0285] <Determination of fiber length and fiber width of pulp fibers, etc.>

[0286] The fiber length and fiber width of unbleached hardwood kraft pulp were determined after the cooking and washing processes. Fiber length and width were measured using a Valmet FS5 fiber analyzer, manufactured by Valmet, according to JIS-P8226:2011 (ISO16065-2:2007) "Pulp—Fiber length determination method based on optical automated analysis". The VALMET FS5 fiber analyzer is a device that measures the length and width of pulp fibers by analyzing images as diluted pulp fibers pass through its internal measuring unit. Based on the measured values, the proportion by mass of pulp fibers with a length of 0.5 mm or more and less than 1.1 mm, and the proportion by mass of pulp fibers with a fiber width of 10 μm or more and less than 35 μm were calculated. Furthermore, the average fiber length and standard deviation σ were calculated for pulp fibers with a fiber length of 0.5 mm or more and less than 1.1 mm, measured at 0.02 mm intervals (with a grading width of 0.02 mm), and the average fiber width and standard deviation σ were calculated for pulp fibers with a fiber width of 10 μm or more and less than 35 μm, measured at 1 μm intervals (with a grading width of 1 μm). The average values ​​(average fiber length and average fiber width) are arithmetic mean. The standard deviations were calculated based on n = 10000 or more measurements using a fiber analyzer. The calculation results are shown in Table 3.

[0287] [Table 3]

[0288]

[0289] <Evaluation>

[0290] The evaluation was conducted as follows. The evaluation results are shown in Table 4.

[0291] (density)

[0292] The density of the fluff pulp sheets in each example was determined in accordance with the test method for thickness, density and specific volume of paper and paperboard as described in JIS-P8118 (2014).

[0293] (Calculation of relative fracture strength)

[0294] The specific bursting strength of the fluff pulp sheets in each example is the value obtained by dividing the bursting strength [kPa] determined according to JIS-P8131 (2009) by the basis weight [kPa·m]. 2 / g).

[0295] (Fiber-decomposing evaluation)

[0296] Based on the aforementioned specific burst strength, the defiberization properties of the fluff pulp sheets in each example were evaluated. The evaluation criteria were the following five stages. Evaluations of A, B, C, and D indicated good defiberization properties of the fluff pulp sheets, with A being excellent. D, while slightly worse, was still a practically acceptable level.

[0297] A: Specific fracture strength is 1.2 kPa·m 2 / g or higher and 1.5 kPa·m 2 / g or less.

[0298] B: Specific fracture strength is 1.6 kPa·m 2 / g or 1.1 kPa·m 2 / g.

[0299] C: Specific fracture strength is 1.7 kPa·m 2 / g or 1.0 kPa·m 2 / g.

[0300] D: Specific fracture strength is 1.8 kPa·m 2 / g or 0.9 kPa·m 2 / g.

[0301] E: Specific fracture strength is 1.9 kPa·m 2 / g or 0.8 kPa·m 2 / g.

[0302] (Determination of Klem water absorption)

[0303] The Klem absorbance of the fluff pulp sheets was determined according to JIS-P8141 (2004), “Paper and paperboard—Test method for water absorption—Klem method”. More specifically, for a basis weight of 200 g / m³, the Klem absorbance of the pulp sheets was determined. 2 The height of each fluff pulp sheet was measured 1 minute after the start of the test [mm]. Based on the height [mm] after 1 minute and 2 minutes after the start of the test, the water absorption rate [mm / min] between 1 minute and 2 minutes after the start of the test was calculated.

[0304] (Water absorption evaluation)

[0305] Based on the height value 1 minute after the start of the above measurement, the water absorption (absorption performance) of the fluff pulp sheet is evaluated according to the following criteria.

[0306] A: The height of the Klem absorbance is between 29 mm and 40 mm one minute after the start of the measurement.

[0307] B: The height of the Klem absorbance is greater than 27 mm and less than 29 mm 1 minute after the start of the measurement.

[0308] C: The height of the Klem absorbent is greater than 25 mm and less than 27 mm 1 minute after the start of the measurement.

[0309] D: The height of the Klem absorbent is less than 25 mm 1 minute after the start of the measurement.

[0310] (Water absorption rate evaluation)

[0311] Based on the water absorption rate values ​​between 1 and 2 minutes after the start of the above measurement, the water absorption rate of the fluff pulp sheet is evaluated according to the following criteria.

[0312] A: The Klem absorbency rate is above 9 mm / min between 1 and 2 minutes after the start of the test.

[0313] B: The Klem absorbance rate is greater than 7 mm / min and less than 9 mm / min between 1 and 2 minutes after the start of the test.

[0314] C: The Klem absorbance rate is greater than 5 mm / min and less than 7 mm / min between 1 and 2 minutes after the start of the test.

[0315] D: The Klem absorbance rate is greater than 3 mm / min and less than 5 mm / min between 1 and 2 minutes after the start of the test.

[0316] E: The absorption rate of the Klem absorbent is greater than 3 mm / min between 1 and 2 minutes after the start of the test.

[0317] (Operational evaluation during fluff pulp manufacturing)

[0318] The operational procedures for manufacturing fluff pulp are as follows: 200 g / m³ of pulp is prepared... 2 Each example of fluff pulp was cut into 2 cm × 2 cm sheets and pulverized using a commercially available mixer (Tescom TM856). The degree of paper dust generation during pulverization was evaluated. Furthermore, the amount of paper dust accumulated during pulverization increased from E to A. The evaluation was conducted in five stages. Evaluations of A, B, C, and D indicate good workability.

[0319] A: When the pulp flakes are crushed, paper dust flies around, and a little pulp accumulates on the walls of the mixer.

[0320] B: When the pulp flakes are crushed, paper dust flies around, and a small amount of pulp accumulates on the walls of the mixer.

[0321] C: When the pulp flakes are crushed, paper dust flies around, and a small amount of pulp accumulates on the walls of the mixer.

[0322] D: When the pulp flakes are crushed, paper dust flies around, and there is a considerable amount of pulp accumulating on the mixer walls, but this is within a reasonable range.

[0323] E: When the pulp flakes are crushed, paper dust flies around and accumulates a lot of pulp on the mixer walls, reaching levels that are unacceptable for actual use.

[0324] (Evaluation of skin inflammation suppression by absorbent products)

[0325] Using the diapers manufactured in the examples described above, a total of 220 subjects each used 10 diapers from any one of the samples numbered No. 1 to 22. That is, 10 subjects evaluated one sample of disposable diapers. The percentage of diapers experiencing inflammation was then assessed. The evaluation was conducted in five stages. Evaluations of A, B, C, and D indicate a better inhibitory effect on skin inflammation than No. 20, which has the same structure as existing products.

[0326] A: The incidence of inflammation is better than No. 20.

[0327] B: The incidence of inflammation is better than No. 20.

[0328] C: The incidence of inflammation is slightly better than No. 20.

[0329] D: The incidence of inflammation is slightly better than No. 20, and it is practically usable.

[0330] E: The incidence of inflammation is the same as No. 20, and at the same level as existing products.

[0331] In addition, the anti-inflammatory effect is related to the reabsorption inhibition effect of the absorbent and the absorption capacity of the absorbent.

[0332] [Table 4]

[0333]

[0334] As shown in Tables 3 and 4, the pulp fibers containing both hardwood and softwood pulp fibers accounted for over 42.6% of the total pulp fibers, with a fiber length of 0.5 mm or more and less than 1.1 mm, and over 90.6% of the total pulp fibers had a fiber width of 10 μm or more and less than 35 μm. Pulps No. 1 to 19, in particular, showed good results in terms of defibrillation properties, operability in fluff pulp manufacturing, and anti-inflammatory effects on absorbent materials.

[0335] <Effect Confirmation Experiment 1>

[0336] Samples of disposable diapers with absorbent elements meeting the conditions shown in Table 5 were prepared (with the same...). Figures 1-6 Using the same construction, the thickness of the absorbent element was measured, a pressure-induced backflow test was conducted, the diffusion area was measured, the absorbent strength was tested, and a polymer shedding test was performed. Additionally, the unit area weight of the packaging sheet, the dry tensile strength of the packaging sheet, and the tensile elongation at break of the packaging sheet in Table 5 are measured values ​​of the raw materials before the formation of the high-compression section.

[0337] The dimensions of each part of samples 1 and 3 are as follows.

[0338] The length d3 of the first high-compression section 51a is 3 mm.

[0339] The major diameter d1 of the second and third high-compression sections is 4.82 mm.

[0340] The short diameter d2 of the second and third high-compression sections is 3 mm.

[0341] First interval 81d: 12.63 mm

[0342] Second interval 82d: 12.63 mm

[0343] The angle of intersection between the first imaginary line 81 and the second imaginary line 82 is 90 degrees.

[0344] In samples 1 and 3, a high-compression zone was formed on the entire surface of the absorber under a pressure of 0.4 MPa. Samples 2 and 4 are comparative examples without a high-compression zone. Furthermore, the conditions other than those shown in Table 5 are common to all samples.

[0345] (Pressure-assisted re-infiltration test)

[0346] This test used a blue test solution prepared by dissolving approximately 5 g of Kiriya Corporation's Brilliant Blue FCF (packaging: powder) in approximately 300 ml of artificial urine, and was conducted according to the following procedure.

[0347] (1) Cut off the sample side seal 12A, open the front sheet F and the rear sheet B, place it on a horizontally set plate with the surface (the surface with the high compression recess) facing upward, and fix the four corners of the sample on the plate with tape so that the inner body 200 is fixed in a flat and unfolded state.

[0348] (2) Place the injection tube (consisting of an acrylic cylindrical part with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm and a square flange of 100 mm × 100 mm × 2 mm in thickness extending around the cylindrical part) at the center of the absorber on the sample surface (the center in the width direction and the center in the front-back direction) and hold it vertically.

[0349] (3) Use a graduated cylinder with the top opening of the injection tube to measure 7 cm. 3 Inject the above blue test solution at a rate of / second for 50 cm. 3 The injection tube is removed from the point where no artificial urine is visible on the sample surface (it has been completely absorbed).

[0350] (4) Remove the injection tube and let it stand for 30 minutes.

[0351] (5) Following (4) above, repeat steps (2) to (4) above.

[0352] (6) Following (5) above, repeat the steps (2) and (3) above.

[0353] (7) After the artificial urine injected for the third time in (6) above has been completely absorbed for 20 minutes, place a 5 kg weight on the injection site of the artificial urine and leave it for 10 minutes. The weight has a flat bottom surface of a square with a length of 100 mm and a width of 100 mm. The length and width of the weight are along the front-back direction and width direction of the sample, and the center of the weight is located on the center of the absorbent. Place the weight on the sample surface.

[0354] (8) The weight (g) of 30 sheets of ADVANTEC qualitative filter paper No. 2 (100 mm x 100 mm square) was determined to three decimal places using an electronic balance.

[0355] (9) Following (7) above, 30 sheets of the above filter paper are sandwiched between the weight and the sample surface with their centers aligned and orientations aligned. After 20 seconds, all the filter paper is removed and its weight (g) is measured to two decimal places. The weight measured before absorption in (5) above is subtracted from the measured weight after absorption to obtain the reabsorption amount.

[0356] (Determination of diffusion area)

[0357] Following the pressurized re-osmosis test described above, keep the sample fixed on a horizontally positioned plate, arrange a ruler next to it, and take a still image of the sample and the ruler from directly above. Use the image analysis software "Fiji" (Fiji IsJust ImageJ) to read the image data, and determine the area of ​​the blue part on the sample surface according to the following steps.

[0358] (1) Start Fiji, select “File” and “Open” in sequence to read the image to be measured.

[0359] (2) Select the “Straight” icon and align it with the 2 points on the ruler scale in the image.

[0360] (3) Select “Analyze” and “Set Scale” in sequence. Enter the actual dimension between the two points merged in (2) above (read from the scale) into “Known distance” and enter the unit in “Unit of length”.

[0361] (4) Select “Image”, “Type”, and “8-bit” in sequence to convert the image to 8-bit.

[0362] (5) Select “Image”, “Adjust”, and “Threshold” in sequence to display the Threshold selection screen. Set the Threshold to 150~210 (Default Red) and check “Dark background” and “Don't reset range”.

[0363] (6) Select “Analize” and “Set Measurements” in sequence, check “Area”, “Mean gray value”, “Min & Max gray value” and “Limit to threshold”, and then select “OK”.

[0364] (7) Select “Polygon selections” and enclose the liquid diffusion range shown in red in (5) above.

[0365] (8) Select “Analyze” and “Mesure” in sequence, and the “Results” will be displayed. The item in “Area” will be used as the diffusion area (set “Unit of length” to cm, and the unit of area to cm). 2 ).

[0366] (Absorbent strength test)

[0367] (1) Cut off the sample side seal 12A, open the front sheet F and the rear sheet B, place it on a horizontally set plate with the surface (the surface with the high compression recess) facing upward, and fix the four corners of the sample on the plate with tape so that the inner body 200 is fixed in a flat and unfolded state.

[0368] (2) At the center of the absorber (the center in the width direction and the center in the front-back direction) and 100 mm behind it, place an injection tube (composed of an acrylic cylindrical part with an inner diameter of 23 mm, an outer diameter of 25 mm, and a height of 100 mm and a square flange extending around the cylindrical part with a length of 100 mm × width of 100 mm × thickness of 2 mm) and hold it vertically.

[0369] (3) Use a graduated cylinder with the top opening of the injection tube, measuring 7 cm. 3 Inject the above blue test solution at a rate of / second for 90 cm. 3 From the start of injection until no artificial urine remains on the sample surface (completely absorbed), place a 300 g weight on the flange of each injection tube to apply an equal load to the flange.

[0370] (4) After placing the weights as described in (3) for 5 minutes, remove the two weights and the rear injection cylinder. Use a measuring cylinder with a 7 cm diameter at the top opening of the central injection cylinder. 3 Inject the above blue test solution at a rate of / second for 90 cm. 3 From the start of injection until no artificial urine remains on the sample surface (completely absorbed), place a 300 g weight on the flange of the central injection tube to apply an even load to the flange.

[0371] (5) After placing the weight as described in (4) for 5 minutes, remove the sample from the plate and mount it on the rotating plate 303 of the impact testing machine 300 described later, and repeatedly strike it at 5-second intervals. In addition, with the rotating plate 303 facing vertically downward in the initial state, the outer surface of the front outer body 12F of the sample is attached to the hook 303F of the rotating plate 303 so that the front-back direction of the sample 320 is along the vertical direction.

[0372] (6) In the above (5) of the impact, the tester observes the shape of the absorber of sample 320 from the front relative to the impact surface 301S. After confirming that a crack has been generated on the absorber, the impact is interrupted after each impact. The width of the crack is measured with a gauge, and the number of impacts when the crack width reaches 3 cm is recorded as the absorber strength.

[0373] (Impact testing machine)

[0374] Figure 27 and Figure 28 This refers to an impact testing machine 300. The impact testing machine 300 includes: a support body 310 consisting of a cuboid frame set on the ground; a light box 301 mounted in the middle of the vertical direction of the back part 311 of the support body 310; a first rotating shaft 302 separated above the light box 301 of the back part 311 and extending horizontally; a flat rotating plate 303 fixed at one end to the first rotating shaft 302 and freely supported in both directions between a vertically downward state and a state in which it rotates to the front side and faces horizontally; a second rotating shaft 304 arranged concentric with the center line extending horizontally along the rotation center line of the first rotating shaft 302; a sample holding arm 305 extending radially from the second rotating shaft 304 and supported by the second rotating shaft 304 in both directions; and a drive source (servo motor) 306 for rotating the sample holding arm 305 in both directions between a vertically downward state and a state in which it rotates to the front side and faces horizontally. The light box 301 has a transparent striking surface 301S on the front, through which the light from the internal illumination (white LED) 301L shines in the frontal direction. Additionally, in its initial state facing vertically downwards, the rotating plate 303 has hooks 303F, which are mechanically fastened to a substantially integral portion covering the frontal surface, allowing the outer surface of the sample 320 to be adhered to these hooks 303F. The sample holding arm 305 has a clamping part 307 and a drive source (not shown) for this operation at its front end. The clamping part 307 holds the lower end of the sample 320 hanging from the vertically downward-facing rotating plate 303. While maintaining this position, the lower end of the sample 320 rotates towards the frontal side until it reaches a substantially horizontal position, releasing the grip. Reference numeral 307C indicates a pair of clamping parts for holding the sample 320 from both sides of the lower end of the sample 320.

[0375] In this impact testing machine 300, after the sample 320 is attached to the rotating plate, in the initial state without the application of external force, such as Figure 27 As shown by the solid line, the sample 320 and the rotating plate 303 are positioned approximately vertically downwards, and the outer surface of the sample 320 is in contact with the striking surface 301S of the lamp box 301. Additionally, the sample holding arm 305 is positioned approximately vertically downwards, with the clamping part 307 at its front end open. At this point, if the test is to begin, it will proceed as follows... Figure 27 As indicated by the arrow and double-dotted line in the middle section, the clamping part 307 automatically closes, holding the lower end of the sample 320 and maintaining this state, while the sample holding arm 305... Figure 27 As indicated by the middle arrow and double-dotted line, rotate the sample until it is approximately horizontal on the front side, thus ensuring that the lower end of the sample 320 is also facing approximately the same direction. Next, as... Figure 27As indicated by the arrow and double-dotted line in the middle section, the clamping part 307 automatically opens, freeing the sample 320 and the rotating plate 303 from external constraints. Due to their own weight, they rotate freely around the first rotating axis 302, and the back of the sample 320 is pinned to the striking surface 301S of the light box 301. Then, the sample clamping arm 305 returns to its initial state. During the test, the striking action (holding, rotating, releasing, and striking) of the sample 320 is repeated at set time intervals. By stopping the test, the sample 320 and the rotating plate 303 are positioned approximately vertically downwards, and the sample 320 stops in a posture along the striking surface 301S of the light box 301. Here, the tester facing the sample 320 can visually identify the shape of the absorber using the illumination light (different transmittance) transmitted through the sample 320 from the light box 301. In particular, the shape of the absorber that has absorbed the aforementioned blue test liquid is easily visible.

[0376] (Polymer shedding test)

[0377] (1) Cut off the side seal 12A of the sample, open the front sheet F and the rear sheet B, and cut off the rear end of the inner body along the rear end of the absorber to expose the rear end of the absorber. In addition, the rear outer body 12B of this sample has a folded portion 12r covering the end of the waist opening WO side of the inner body 200, so the folded portion 12r is peeled off and removed by cold spraying.

[0378] (2) With the rotating plate 303 of the impact testing machine 300 facing vertically downwards in the initial state, the outer surface of the front outer casing 12F of the sample 320 is attached to the hook material 303F of the rotating plate 303, such that the front-back direction of the sample 320 is aligned with the vertical direction. Additionally, a recovery tray (not shown) for catching highly absorbent polymer particles is placed 10 cm below the impact surface 301S. Then, the impact is repeated 30 times at 5-second intervals.

[0379] (3) After the impact in (2) above, the weight of the fallen material in the recovery tray is measured and recorded as the amount of detached polymer.

[0380] The experimental results are shown in Table 5.

[0381] [Table 5]

[0382]

[0383] Sample 1, which has an absorbent containing broadleaf pulp fibers and a high-compression section formed on the absorbent element, exhibits higher absorbent strength compared to the common sample 2, except that it lacks the high-compression section. Furthermore, it possesses absorbent strength at the same level as sample 3, which has an absorbent element composed solely of softwood pulp fibers. Additionally, the diffusion area of ​​sample 1 is significantly higher than that of sample 2, and is at the same level as sample 3, which has an absorbent element composed solely of softwood pulp fibers. Moreover, sample 1 shows significantly less rewetting than sample 2, a result worthy of special mention. Furthermore, sample 1 shows less polymer shedding compared to sample 2, a result at the same level as sample 3, which has an absorbent element composed solely of softwood pulp fibers. Moreover, a comparison of samples 1 and 2, and samples 3 and 4, reveals that the formation of the high-compression section reduces the thickness of the absorbent element. A comparison of samples 1 and 3 shows that the inclusion of broadleaf pulp fibers further reduces the thickness of the absorbent element.

[0384] <Explanation of terms in the instruction manual>

[0385] In this specification, unless otherwise stated, the following terms have the following meanings.

[0386] • “Front-back direction” refers to the direction indicated by the label LD in the figure (longitudinal direction), and “width direction” refers to the direction indicated by the label WD in the figure (left-right direction). The front-back direction and the width direction are orthogonal.

[0387] • "Front side" refers to the side of the garment that is closest to the wearer's skin when worn, while "back side" refers to the side of the garment that is furthest from the wearer's skin when worn.

[0388] • "Surface" refers to the side of the garment that is close to the wearer's skin when worn, while "back" refers to the side that is away from the wearer's skin when worn.

[0389] • "Elongation" refers to the value when the natural length is set to 100%. For example, an elongation of 200% is synonymous with an elongation ratio of 2.

[0390] • “Artificial urine” is a mixture of urea: 2 wt%, sodium chloride: 0.8 wt%, calcium chloride dihydrate: 0.03 wt%, magnesium sulfate heptahydrate: 0.08 wt%, and ion-exchanged water: 97.09 wt%.

[0391] • “Gel strength” was determined as follows: 1.0 g of highly absorbent polymer was added to 49.0 g of artificial urine and stirred with a stirrer. The resulting gel was placed in a constant temperature and humidity bath at 40°C × 60% RH for 3 hours and then allowed to return to room temperature. The gel strength was measured using a curd penetration meter (manufactured by I. Techno Engineering: Curdmeter-MAX ME-500).

[0392] • “Weight per unit area” is determined as follows: The sample or test piece is pre-dried and then placed in a test chamber or apparatus under standard conditions (temperature 23 ± 1°C, relative humidity 50 ± 2%) until it reaches a constant weight. Pre-drying refers to bringing the sample or test piece to a constant weight at 100°C. Alternatively, pre-drying is not necessary for fibers with a standard moisture regain of 0.0%. Using a sampling template (100 mm × 100 mm), 100 mm × 100 mm samples are cut from the constant-weight test piece. The weight of the sample is measured, multiplied by 100, and the weight per square meter is calculated as the weight per unit area.

[0393] • A thickness gauge (Peacock type micrometer thickness gauge, model H (measuring range: 0~10 mm, probe: 10 mm diameter circular pressure plane, measuring force: approximately 1.7 N, pressure: approximately 21.7 kPa)) from Ozaki Manufacturing Co., Ltd. was used for measurement. The sample and the thickness gauge were leveled before measuring the thickness of thicker components such as the absorber 56 and absorber 50. The thickness of the absorber 50 (non-high compression section 52) was determined as follows: In the non-high compression section 52 of the absorber 50, 10 locations with the largest inscribed circles tangent to the outer shape of the non-high compression section 52 were selected. The thickness measured by aligning the center of the probe of the thickness gauge with the center of the inscribed circle of that region was taken as the thickness of the absorber 50 (non-high compression section 52).

[0394] The “thickness” of the high-compression section 51 is obtained by subtracting the depth of the high-compression section 51 from the thickness of the absorber 50 (non-high-compression section 52).

[0395] The "depth" of the high-compression portion 51 is measured using a One Shot 3D Measurement Macro Scope VR-3200 or equivalent manufactured by Keyence Corporation, the observation application "VR-H2V" and the analysis application "VR-H2A," or equivalent software thereof. In principle, the magnification is 12x and the field of view is 24 mm × 18 mm, but the magnification and field of view can be varied depending on the size of the high-compression portion 51. During the specific depth measurement, the aforementioned observation application is activated, the sample is placed on the microscope stage so that the high-compression portion 51 of the object being measured is within the field of view, and the "Measure" button is pressed. Then, the aforementioned analysis application is executed to analyze the measured 3D information. (See reference...) Figure 23The analysis steps are explained below. Specifically, using the aforementioned analysis application, the depth (measured cross-sectional curve) profile of the line segment Q1 passing through the center (or centroid in the case of a circle) of a highly compressed portion 51 in the image portion (XY portion in the figure), represented by a planar observation point, is obtained. Based on this depth profile's cross-sectional curve, the surface roughness component with a shorter wavelength than λc: 800 μm (where λc is the "filter defining the boundary between roughness component and waviness component" described in JIS-B0601 "3.1.1.2") is removed using a low-pass filter. Two boundary points P1 and P2 are then defined: a position where the curvature is approximately flat, or a position where the curvature is strongest and convex upwards. The minimum height of the area enclosed by these boundary points P1 and P2 is then calculated. Furthermore, the average height value of the boundary points P1 and P2 is taken as the maximum height. Finally, the depth of the highly compressed portion 51 is calculated by subtracting the minimum height from the maximum height. Additionally, boundary points P1 and P2 are selected visually. When making this selection, an image of the high-compression section 51 from a planar viewpoint can be referenced. The above measurements are performed on any 10 high-compression sections 51 designed with the same size and shape, and the results are taken as their average value.

[0396] The diameter or spacing of the high-compression portion 51 is measured using a One Shot 3D Measurement Macro Scope VR-3200 or equivalent manufactured by Keyence Corporation, along with the observation application "VR-H2V" and the analysis application "VR-H2A," or equivalent software thereof. In principle, the magnification is 12x and the field of view is 24 mm × 18 mm, but the magnification and field of view can be varied depending on the size of the high-compression portion 51. Specifically, when measuring the size, the aforementioned observation application is activated, the sample is placed on the microscope stage, and the "Measure" button is pressed to position the high-compression portion 51 of the object being measured within the field of view. Then, the aforementioned analysis application is executed to analyze the measured 3D information.

[0397] The following reference Figure 23The analytical process for determining the diameter of the high-compression section 51 will be explained. Specifically, using the aforementioned analysis application, the depth (measured cross-sectional curve) profile of the line segment Q1 passing through the high-compression section 51 of the object along an arbitrary diameter direction is obtained in the image section represented by a planar viewpoint (XY portion in the figure). Based on the cross-sectional curve of this depth profile, the surface roughness component with a shorter wavelength than λc: 800 μm (where λc is the "filter defining the boundary between roughness component and waviness component" described in JIS-B0601 "3.1.1.2") is removed by passing through a low-pass filter. The intersection points of this curve with the straight line Q3, which is parallel to the X-axis located at a distance of L + 0.25 mm from the lowest point 51, are designated as P3 and P4. The distance X1 in the X-axis direction of these intersection points P3 and P4 is defined as the diameter of the high-compression section 51. The above measurements were performed on any 10 high-compression sections 51 designed with the same size and shape, and the results were taken as their average value.

[0398] Additionally, refer to Figure 23 The analytical steps for the spacing between adjacent high-compression sections 51 will be explained. Specifically, using the aforementioned analysis application, in the image section represented by a planar observation point, the depth (measured cross-sectional curve) profile of the line segment Q1 passing through two adjacent high-compression sections 51 along the object's spacing direction is obtained. Based on this depth profile cross-sectional curve, the surface roughness component with a shorter wavelength than λc: 800 μm (where λc is the "filter defining the boundary between roughness component and waviness component" described in JIS-B0601 "3.1.1.2") is removed by passing through a low-pass filter. In the "profile curve Q2" of the image section (XZ portion in the figure), represented by a cross-sectional viewpoint, the intersection points of the straight line Q3 parallel to the X-axis located at a distance of L + 0.25 mm from the lowest point 51 are set as P3, P4, P5, and P6. The distance X2 in the X-axis direction between the two intermediate adjacent intersection points P4 and P5 is set as the spacing between the high-compression sections 51. The above measurements were performed on any five adjacent high-pressure compression sections 51 designed with the same size and shape, and the results were their average values.

[0399] • The “thickness” of non-woven fabrics and other thin sheets was measured using an automatic thickness gauge (KES-G5 handheld compression gauge program) at a load of 0.098 N / cm. 2 and pressure area: 2 cm 2 Automatically measured under certain conditions.

[0400] The area of ​​the high-compression portion 51 is measured using the One Shot 3D Measurement Macro Scope VR-3200 or equivalent manufactured by Keyence Corporation, the observation application "VR-H2V" and the analysis application "VR-H2A", or equivalent software thereof. In principle, the magnification is set to 12x and the field of view area is set to 24 mm × 18 mm, but the magnification and field of view area can be changed according to the size of the high-compression portion 51. Specifically, when measuring the area, the aforementioned observation application is started, the sample is placed on the microscope stage so that the high-compression portion 51 of the object being measured is within the field of view, and the "Measure" button is pressed. Next, the aforementioned analysis application is executed, and to analyze the 3D information of the measurement, the "Volume / Area" button is pressed to switch to the volume / area measurement screen. In the volume / area measurement screen, the "Concave" button is pressed, followed by the "Set Measurement Area" button, and then the "Minimum Height" button is pressed from "Auxiliary Tools 2" to specify an area that includes one high-compression portion 51 as the object, and the lowest point within the display area is selected. Next, select "Auto Extract (Elevation)" from the "Feature Tools" menu, specify the lowest point as the reference point, and set the intersection height to +0.25 mm. Press the "OK" button. Return to the volume / area measurement screen, and use the value displayed as the area of ​​the portion from the lowest point in the specified area to a height of 0.25 mm as the area of ​​the high compression section 51. Perform the above measurement on any five high compression sections 51 designed with the same size and shape, and use the results as their average value.

[0401] • “Area ratio” refers to the proportion of the area of ​​the object portion per unit area. It is calculated by dividing the total area of ​​the object portion (e.g., the high-compression portion 51) that occupies the entire object region (e.g., the back side of the absorber 50) by the area of ​​the object region, expressed as a percentage. When calculating the area ratio of the high-compression portion 51, the entire rectangular region circumscribed by the high-compression portion 51 is taken as the object region, and the total area of ​​the high-compression portion 51 is calculated based on the area of ​​the high-compression portion 51 described below. That is, when five or more high-compression portions 51 designed with the same size and shape are provided, the area of ​​the high-compression portion 51 designed is the average value of all the high-compression portions 51 measured by the above-described method for measuring the area of ​​the high-compression portion 51. On the other hand, when the size and shape of the high-compression portion 51 are irregular, or when there are fewer than five high-compression portions 51 designed with the same size and shape, the area of ​​each high-compression portion 51 is measured individually using the above-described method for measuring the area of ​​the high-compression portion 51 (without calculating the average value).

[0402] • The “water absorption” was determined according to JIS K7223-1996 “Test method for water absorption of superabsorbent resins”.

[0403] • "Water absorption rate" refers to the time to the endpoint when using 2 g of superabsorbent polymer and 50 g of physiological saline to perform the JIS K7224-1996 "Test method for water absorption rate of superabsorbent resin".

[0404] • "Unfolded state" refers to a state in which there is no contraction (including all contractions such as contraction caused by elastic components) or a relaxed and flat unfolded state.

[0405] Unless otherwise specified, the dimensions of each part refer to the dimensions in the unfolded state, not the natural length state.

[0406] • Where no environmental conditions are specified in the test or measurement, the test or measurement shall be conducted in a laboratory or apparatus under standard conditions (temperature 23 ± 1°C, relative humidity 50 ± 2%).

[0407] Industrial applicability

[0408] In addition to disposable diapers such as trouser-type disposable diapers, belt-type disposable diapers, and pad-type disposable diapers, this invention can also be used for all absorbent items with absorbent bodies, such as sanitary napkins and pet diapers.

[0409] Figure Labels

[0410] 11...Impermeable sheet, 12A...Side seal, 12B...Rear outer casing, 12E...Waist extension, 12F, 12B...Outer casing, 12F...Front outer casing, 12S, 12H...Sheet, 13...Covering nonwoven fabric, 16, 19...Elastic component below waist, 17...Waist elastic component, 18...Unnecessary elastic component, 20...Inner casing joint, 200...Inner casing, 30...Top sheet, 40...Intermediate sheet, 50...Absorbent, 50P...Packaging body, 51...High-compression section, 51a...First high-compression section, 51b...Second high-compression section, 51c...Third high-compression section, 52...Non-high-compression section, 56...Absorbent, 56f...Pulp fiber, 56p...Highly absorbent polymer particles, 56L...Low weight per unit area section, 58...Packaging sheet, 60...Stand-up pleats, 60A...Front end Side section, 60B... root side section, 62... pleated piece, 63... pleated elastic component, 67... folded section, 68... upright section, 70... side wing, 71... first layer, 72... second layer, 73... side elastic component, 81... first imaginary straight line, 82... second imaginary straight line, 90... anvil roller, 91... protrusion, 92... smooth roller, A1... non-stretchable area, A2... stretchable area, B... back panel, C... hip cover, F... front panel, HM... hot melt adhesive, HM1... first hot melt adhesive, HM2... second hot melt adhesive, L... middle area, LD... front and back direction, LO... leg opening, M... crotch, SG... side stretchable area, T... waist area, TD... thickness direction, U... lower waist, W... waist, WD... width direction, WO... waist opening.

Claims

1. An absorbent article, characterized in that, It has a crotch area. The device includes an absorbent component comprising an absorbent body disposed in a front-to-back direction including the crotch area, and a packaging sheet covering the absorbent body. The absorbent is made by mixing and aggregating pulp fibers containing broadleaf pulp fibers and highly absorbent polymer particles. The absorbent is provided with a plurality of highly compressed portions along its thickness direction at intervals, such that at least one of the surfaces of the absorbent is recessed into the absorbent body. The portion outside the high-compression sections in the arrangement area of ​​the plurality of high-compression sections is a non-high-compression section that is thicker and lower in density than the high-compression sections. The density of the absorber in the high-compression section is 60,000~250,000 g / m³. 3 , The area of ​​each of the high-compression sections is 2~200 mm. 2 .

2. An absorbent article, characterized in that, It has a crotch area. The device includes an absorbent component comprising an absorbent body disposed in a front-to-back direction including the crotch area, and a packaging sheet covering the absorbent body. The absorbent is made by mixing and aggregating pulp fibers containing broadleaf pulp fibers and highly absorbent polymer particles. The absorbent is provided with a plurality of highly compressed portions along its thickness direction at intervals, such that at least one of the surfaces of the absorbent is recessed into the absorbent body. The portion outside the high-compression sections in the arrangement area of ​​the plurality of high-compression sections is a non-high-compression section that is thicker and lower in density than the high-compression sections. The shortest distance between each of the plurality of high-compression sections and the nearest other high-compression section is 1 to 4 mm.

3. The absorbent article according to claim 1 or 2, wherein, The area ratio of the high-compression sections in the arrangement region of the plurality of high-compression sections is 10-35%. The diameter of the largest inscribed circle tangent to the shape of the non-high compression portion is 30 mm or less.

4. The absorbent article according to claim 3, wherein, The high-compression section has an external shape without inflection points or bending points, and the diameter of the largest inscribed circle tangent to the external shape of the high-compression section is 1 to 10 mm, and the circumference of the external shape of the high-compression section is 1 to 15 times the circumference of the largest inscribed circle tangent to the external shape of the high-compression section.

5. The absorbent article according to claim 3, wherein, In the arrangement area of ​​the plurality of high-compression sections, an imaginary grid is defined. The imaginary grid is formed by repeatedly arranging a first imaginary straight line along a first direction at a first interval in a second direction at a clockwise inclination of 80-90° relative to the first imaginary straight line, and repeatedly arranging a second imaginary straight line along the second direction at a second interval in the first direction. And when determining the smallest imaginary quadrilateral with the intersection of the first imaginary line and the second imaginary line as its vertex, The high-compression section includes: a first high-compression section disposed at the intersection of the first imaginary line and the second imaginary line; a second high-compression section disposed between adjacent first high-compression sections in the first imaginary line and between adjacent first high-compression sections in the second imaginary line; and a third high-compression section disposed at the intersection of the diagonals of the imaginary quadrilateral. The first high-compression section is circular with the intersection of the first imaginary straight line and the second imaginary straight line as its center. The second high-compression section is an ellipse or rounded rectangle with a centroid at the midpoint of each side of the imaginary quadrilateral and having a major axis along each side. The third high-compression section is an ellipse or rounded rectangle with a centroid at the intersection of the diagonals of the imaginary quadrilateral and a major axis along the front-back direction, or a circle centered at the intersection of the diagonals of the imaginary quadrilateral.

6. The absorbent article according to claim 5, wherein, The diameter of the first high-compression section is 1~4 mm. The major axis of the second high-compression section is 3-6 mm long, and the length of the minor axis is equal to the diameter of the first high-compression section. The third high-compression section has the same size and shape as the second high-compression section, except that its major axis is oriented in the front-to-back direction. The minimum interval between adjacent first high-compression sections and second high-compression sections is 1~2 mm.

7. The absorbent article according to claim 3, wherein, The imaginary grid is a tilted grid shape in which the first imaginary straight line is tilted 40-50° clockwise relative to the front-back direction when viewed from above, and the second imaginary straight line is tilted 40-50° counterclockwise relative to the front-back direction when viewed from above.

8. The absorbent article according to claim 1 or 2, wherein, The weight per unit area of ​​the pulp fibers in the absorber is 100~500 g / m³. 2 , The weight ratio of pulp fiber to highly absorbent polymer particles in the absorbent is 40:60~65:

35. The thickness of the non-high-compression section is 3~13 mm. The thickness of the high-compression section is 60-90% of the thickness of the non-high-compression section.

9. The absorbent article according to claim 1 or 2, wherein, Of all the pulp fibers in the absorber, the proportion of pulp fibers with a length of 0.5 mm or more and less than 1.1 mm is 40% or more by mass, and the proportion of pulp fibers with a width of 10 μm or more and less than 35 μm is 90% or more by mass.

10. The absorbent article according to claim 9, wherein, The absorbent's pulp fibers are composed of coniferous pulp fibers and broadleaf pulp fibers. The mass ratio of the broadleaf pulp fiber to the coniferous pulp fiber is 25 / 75 or more and 38 / 62 or less.

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