Absorbent article

Abstract

[Problem] To improve visibility of an alignment mark printed part on a surface of a liquid impermeable sheet. [Solution] The problem is solved by an absorbent article comprising: an absorbent body 56; a liquid-permeable top sheet 30 disposed on the front side of the absorbent body 56; a liquid-impermeable sheet 11 disposed on the back side of the absorbent body 56; and side flap parts SF that extend laterally from both respective side edges of the absorbent body 56 and do not have the absorbent body 56, wherein the side flap parts SF includes the liquid-impermeable sheet 11 and a front-side cover member that covers the front side of the liquid-impermeable sheet 11. Alignment mark printed parts 21-25 are printed on the front surface of the liquid-impermeable sheet 11 on the side flap parts SF, and back surface printed parts 91-95 are printed on the back surface of the liquid-impermeable sheet 11 on the side flap parts SF such that 50% or more of the area of the alignment mark printed parts 21-25 overlap with the back surface printed parts.

Description

Absorbent articles

[0001] The present invention relates to absorbent articles such as disposable diapers, sanitary napkins, and pet sheets, which have printing on a liquid-impermeable sheet.

[0002] Absorbent articles such as disposable diapers and sanitary napkins generally consist of an absorbent core, a liquid-permeable top sheet placed on the front side of the absorbent core, and a liquid-impermeable sheet placed on the back side of the absorbent core. In such absorbent articles, alignment marks used to position the product on the wearer's body were sometimes printed on the surface of the liquid-impermeable sheet so that they could be seen from the inside of the product (see Patent Document 1).

[0003] However, since liquid-impermeable sheets are generally covered by a top sheet or other front-side cover member and are not exposed to the surface of absorbent articles, the alignment mark printed on the surface of the liquid-impermeable sheet had to be viewed through the front-side cover member, leaving room for improvement in the visibility of the alignment mark printed on the sheet.

[0004] Japanese Patent Publication No. 2023-182379 Japanese Patent Publication No. 2017-205193

[0005] Therefore, the main objective of the present invention is to improve the visibility of the alignment mark printed on the surface of a liquid-impermeable sheet.

[0006] The absorbent article that solves the above problems is as follows: <First Embodiment> An absorbent article having an absorbent body, a liquid-permeable top sheet disposed on the front side of the absorbent body, and a liquid-impermeable sheet disposed on the back side of the absorbent body, and having a flap portion that extends outward from the outer peripheral edge of the absorbent body and does not have the absorbent body, wherein the flap portion has the liquid-impermeable sheet and a front cover member that covers the front side of the liquid-impermeable sheet, wherein an alignment mark printing portion is printed on the surface of the liquid-impermeable sheet in the flap portion, and a back printing portion is printed on the back side of the liquid-impermeable sheet in the flap portion such that 50% or more of the area of ​​the alignment mark printing portion overlaps.

[0007] (Effects) The characteristic of this absorbent article is that the back side is printed on the back of the liquid-impermeable sheet, and the alignment mark printing area is printed on the front of the liquid-impermeable sheet so that more than 50% of the area overlaps with the back side printing area. As a result, when the user looks at the absorbent article from the front side, the color of the overlapping area between the alignment mark printing area and the back side printing area appears darker than if only the alignment mark printing area were printed, thus improving the visibility of the alignment mark printing area.

[0008] <Second Embodiment> The absorbent article of the first embodiment, wherein the brightness L* value of the overlapping portion between the alignment mark printing portion and the back surface printing portion on the surface of the absorbent article is 80 or less, and the brightness L* value around the overlapping portion between the alignment mark printing portion and the back surface printing portion is 85 or more.

[0009] (Effects) Factors that affect the visibility of the alignment mark printed area on the surface of an absorbent article, such as the color of the alignment mark printed area and the back side printed area, the liquid-impermeable sheet, and the front side cover member, can be determined as appropriate. However, it is preferable to configure the article to satisfy the conditions of this embodiment, for example, because it results in good visibility of the alignment mark printed area.

[0010] Note that the L* value of lightness refers to the lightness in the "Colorimetry - Part IV: CIE 1976 L*a*b* color space" as defined in JIS Z 8781-4:2013.

[0011] <Third Embodiment> The absorbent article according to the first or second embodiment, wherein the back surface printing area is a registration mark printed on the back surface of the liquid-impermeable sheet.

[0012] (Effects) As in this embodiment, instead of providing the back surface printing area solely for improving the visibility of the alignment mark printing area, it is preferable to use it for register marks for transport control of liquid-impermeable sheets, etc., because this improves not only the visibility of the alignment mark printing area but also the detectability of the register marks.

[0013] <Fourth Embodiment> An absorbent article according to any one of the first to third embodiments, wherein the alignment mark printing area is printed so as to include the entirety of the back surface printing area.

[0014] (Effects) If the back-side printing area extends beyond the outer edge of the alignment mark printing area, the visible shape of the alignment mark printing area may appear different from the printed shape of the alignment mark printing area (due to the extended portion of the back-side printing area). In contrast, as in this embodiment, if the alignment mark printing area and the back-side printing area are printed so that the entire back-side printing area is included within the alignment mark printing area, there is no risk that the visible shape of the alignment mark printing area will appear different from the printed shape of the alignment mark printing area, which is preferable.

[0015] <Fifth Embodiment> The flap portion has a back cover member that covers the back side of the liquid-impermeable sheet, the opacity of the front cover member is 15 to 30%, the opacity of the unprinted portion of the liquid-impermeable sheet is 20 to 60%, and the opacity of the back cover member is 20 to 40%, an absorbent article according to any one of the first to fourth embodiments.

[0016] (Effects) It is preferable that the opacity of the liquid-impermeable sheet, the front cover member, and the back cover member be within the range of this embodiment in order to improve the visibility of the alignment mark printed area (and the detectability of the back printed area if it is a registration mark).

[0017] <Sixth Embodiment> An absorbent article according to any one of the first to fifth embodiments, having a crotch portion including the center in the front-to-back direction, an abdominal portion extending forward from the center in the front-to-back direction, and a dorsal portion extending backward from the center in the front-to-back direction, wherein the absorbent body is provided in the area including the crotch portion, the flap portion includes side flap portions that extend laterally from both side edges of the absorbent body in the dorsal portion, connecting portions are provided on both sides of the dorsal portion which are detachably connected to the outer surface of the abdominal portion, the side flap portion of the dorsal portion has a portion of the front cover member consisting of three or fewer sheet layers, and the alignment mark printing portion and the back printing portion are printed on the liquid-impermeable sheet in the portion of the side flap portion of the dorsal portion where the front cover member consists of three or fewer sheet layers.

[0018] (Effects) In the case of a connected type absorbent article like the one in this embodiment, the absorbent article is often placed under the wearer's buttocks, and the front, back, left, and right positions of the absorbent article are often determined by using the side flaps of the absorbent article that extend beyond the wearer's body on both sides, and the connecting parts provided thereon, as a guide. Therefore, it is preferable to provide the alignment mark printing area on the side flaps as in this embodiment. However, in the case of a connected type absorbent article like the one in this embodiment, the side flaps may have a portion where the front cover member consists of four or more sheet layers, and in such cases, the visibility of the alignment mark printing area may be poor. Therefore, it is preferable that the alignment mark printing area and the back printing area are provided on the portion of the side flaps where the cover member consists of three or fewer sheet layers, as in this embodiment.

[0019] According to the present invention, the visibility of the alignment mark printed on the surface of a liquid-impermeable sheet can be improved.

[0020] This is a plan view of the inner surface of a tape-type disposable diaper in its unfolded state. This is a plan view of the outer surface of a tape-type disposable diaper in its unfolded state. This is a cross-sectional view taken along line 6-6 in Figure 1. This is a cross-sectional view taken along line 7-7 in Figure 1. This is a cross-sectional view taken along line 5-5 in Figure 1. This is a cross-sectional view taken along line 9-9 in Figure 1. This is a cross-sectional view taken along line 8-8 in Figure 1. This is a cross-sectional view along the width direction of the waist elasticity area. (a) Cross-sectional view of the elasticity sheet in the unfolded state, (b) Cross-sectional view of the elasticity sheet in the natural length state, and (c) Cross-sectional view of the elasticity sheet in the worn state. (a) Cross-sectional view of the elasticity sheet in the unfolded state, (b) Cross-sectional view of the elasticity sheet in the natural length state, and (c) Cross-sectional view of the elasticity sheet in the worn state. This is a cross-sectional view along the width direction of the area having the alignment mark printing area and the back printing area. (a) Plan view showing the alignment mark printing area, (b) Plan view showing the back printing area, and (c) Plan view showing the alignment mark printing area and the back printing area. (a) A plan view showing the alignment mark printing area, (b) A plan view showing the back printing area, and (c) A plan view showing the alignment mark printing area and the back printing area. (a) A plan view showing the alignment mark printing area, (b) A plan view showing the back printing area, and (c) A plan view showing the alignment mark printing area and the back printing area. A plan view showing the inside of a tape-type disposable diaper in the unfolded state. A plan view showing the inside of a tape-type disposable diaper in the unfolded state.

[0021] The following is a detailed explanation of an example of an absorbent article, with reference to the attached drawings. The dotted pattern in the cross-sectional view indicates the adhesive used as a joining means to connect the various components located on its front and back sides. This adhesive is formed by applying hot-melt adhesive in solid, bead, curtain, summit, or spiral coats, or by pattern coating (transfer of hot-melt adhesive using a relief printing method). Alternatively, the fixing portion of the elastic stretchable member is formed by applying the adhesive to the outer surface of the elastic stretchable member using a comb gun or SureWrap, either in conjunction with or in conjunction with these methods. Examples of hot-melt adhesives include EVA-based, adhesive rubber-based (elastomer-based), olefin-based, and polyester / polyamide-based adhesives, but they are not particularly limited in their use. As a joining means to connect the various components, material welding methods such as heat sealing or ultrasonic sealing can also be used.

[0022] Figures 1 to 9 show a tape-type disposable diaper as an example of an absorbent article. In the figures, the symbol X indicates the total width of the diaper excluding the connecting tape 13, and the symbol L indicates the total length of the diaper. This tape-type disposable diaper has a crotch area including the center of the front-to-back LD, a ventral area F extending forward from the center of the front-to-back LD, and a dorsal area B extending backward from the center of the front-to-back LD. This tape-type disposable diaper also has an absorbent body 56 embedded in the area including the crotch area, a liquid-permeable top sheet 30 covering the front side of the absorbent body 56, a liquid-impermeable sheet 11 covering the back side of the absorbent body 56, and an outer nonwoven fabric 12 covering the back side of the liquid-impermeable sheet 11 and forming the outer surface of the product. Both side edges of the tape-type disposable diaper have a constricted portion along the leg circumference in the middle of the front-to-back LD, and connecting tapes 13 are provided on the dorsal side of this constricted portion.

[0023] The following describes the materials and characteristics of each part in order. (Absorbent) The shape of the absorbent 56 can be a rectangle as shown in the example, or it can have a shape with a constriction in the middle of the front-to-back direction that follows the legs (like an hourglass). Reference numeral 56x indicates the total width of the absorbent 56. The absorbent 56 is the part that absorbs and retains excretory fluid and can be formed from an aggregate of fibers. As for this fiber aggregate, in addition to stacked short fibers such as cotton pulp or synthetic fibers, a filament aggregate obtained by opening tows (fiber bundles) of synthetic fibers such as cellulose acetate as needed can also be used. As for the fiber basis weight, when stacking cotton pulp or short fibers, for example 100 to 300 g / m ２ The density can be set to a certain extent, and in the case of filament aggregates, for example, 30 to 120 g / m². ２ The fineness can be set to a certain degree. In the case of synthetic fibers, the fineness is, for example, 1 to 16 dtex, preferably 1 to 10 dtex, and more preferably 1 to 5 dtex. In the case of filament aggregates, the filaments may be non-crimped fibers, but crimped fibers are preferred.

[0024] (Superabsorbent Polymer Particles) The absorbent material 56 may contain superabsorbent polymer particles in part or in whole. Superabsorbent polymer particles include not only "particles" but also "powder". Superabsorbent polymer particles used in this type of absorbent article can be used as they are. The particle size of the superabsorbent polymer particles is not particularly limited, but it is desirable that, for example, when sieving is performed using a 500 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), and the particles that fall below the sieve are sieved using a 180 μm standard sieve (JIS Z8801-1:2006) (shaking for 5 minutes), the proportion of particles remaining on the 500 μm standard sieve is 30% by weight or less, and the proportion of particles remaining on the 180 μm standard sieve is 60% by weight or more.

[0025] While there are no particular limitations on the material used for the superabsorbent polymer particles, those with a water absorption capacity of 40 g / g or more are preferred. Examples of superabsorbent polymer particles include starch-based, cellulose-based, and synthetic polymer-based materials. Starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, crosslinked sodium carboxymethylcellulose, and acrylic acid (salt) polymers can be used. While the commonly used granular form is preferred for the superabsorbent polymer particles, other forms can also be used.

[0026] The basis weight of the superabsorbent polymer particles can be appropriately determined according to the amount of absorption required for the application of the absorbent material 56. Therefore, it is not possible to generalize, but typically it is 50 to 350 g / m². ２ It can be done this way.

[0027] (Packaging Sheet) To prevent the escape of superabsorbent polymer particles, or to improve the shape retention of the absorbent body 56, the absorbent body 56 can be incorporated as an absorbent element 50 wrapped in a packaging sheet 58. As the packaging sheet 58, tissue paper, especially crepe paper, nonwoven fabric, poly-laminated nonwoven fabric, or a sheet with small holes can be used. However, it is desirable that the sheet prevents the escape of superabsorbent polymer particles. When using nonwoven fabric instead of crepe paper, hydrophilic SMMS (spunbond / meltblown / meltblown / spunbond) nonwoven fabric is particularly suitable, and the material can be polypropylene, polyethylene / polypropylene, etc. The fiber basis weight is 5 to 40 g / m². ２ , especially 10-30 g / m ２ That would be preferable.

[0028] As shown in Figure 3, the packaging sheet 58 may be structured to wrap the entire absorbent material 56 with a single sheet, or it may be structured to wrap the entire absorbent material 56 with multiple sheets, such as two sheets for the top and bottom. The packaging sheet 58 may also be omitted.

[0029] (Top sheet) The top sheet 30 is permeable to liquids, and for example, a perforated or non-perforated nonwoven fabric or a porous plastic sheet can be used.

[0030] The top sheet 30 extends from the front to the rear of the product in the front-to-back direction (LD) and laterally beyond the absorbent 56 in the width direction (WD). However, as needed, the width of the top sheet 30 can be made shorter than the total width of the absorbent 56, for example, if the starting point of the rise-up gather 60 (described later) is located closer to the center in the width direction (WD) than the side edge of the absorbent 56. In the illustrated example, the top sheet 30 forms a rectangle with both side edges facing each other in the front-to-back direction, but it may be other than a rectangle.

[0031] (Intermediate Sheet) To prevent the liquid that has permeated through the top sheet 30 from flowing back, an intermediate sheet (also called a "second sheet") 40 can be provided on the back side of the top sheet 30. The intermediate sheet 40 can also be omitted.

[0032] Various nonwoven fabrics can be suitably used as the intermediate sheet 40, and bulky air-through nonwoven fabrics are particularly suitable. It is preferable to use a core-sheath composite fiber for the air-through nonwoven fabric. In this case, the resin used for the core may be polypropylene (PP), but highly rigid polyester (PET) is preferred. The basis weight is 17-80 g / m². ２ Preferably, 25 to 60 g / m ２ This is more preferable. The thickness of the raw fibers for the nonwoven fabric is preferably 2.0 to 10 dtex. In order to make the nonwoven fabric bulky, it is also preferable to use off-center fibers without a core in the center, hollow fibers, or off-center and hollow fibers as all or part of the mixed fibers of the raw fibers.

[0033] In the illustrated example, the intermediate sheet 40 is shorter than the width of the absorbent material 56 and positioned in the center, but it may also be provided across the entire width of the absorbent material 56. In addition, the intermediate sheet 40 can be provided continuously across the entire length L of the diaper as in the illustrated example, or it can be provided only between the front edge and the rear edge of the absorbent material 56.

[0034] (Liquid-impermeable sheet) The liquid-impermeable sheet 11 is not particularly limited, but it is preferably permeable to moisture. As the liquid-impermeable sheet 11, for example, a microporous sheet obtained by kneading an inorganic filler into an olefin resin such as polyethylene or polypropylene, forming a sheet, and then stretching it in a uniaxial or biaxial direction can be suitably used. In addition, as the liquid-impermeable sheet 11, a nonwoven fabric with enhanced waterproofing properties can also be used.

[0035] It is desirable that the liquid-impermeable sheet 11 extends over the same or a wider area than the absorbent body 56 in the front-to-back direction (LD) and the width direction (WD). However, if necessary, such as when other waterproofing means are present, the sheet may be constructed so as not to cover the edges of the absorbent body 56 in the front-to-back direction (LD) and the width direction (WD). If necessary, such as when the outer nonwoven fabric 12 described later is omitted, the liquid-impermeable sheet 11 may extend to the periphery of the diaper. In the illustrated example, the liquid-impermeable sheet 11 forms a rectangle with both side edges facing each other in the front-to-back direction, but it may be other than a rectangle.

[0036] (Outer Nonwoven Fabric) The outer nonwoven fabric 12 covers the entire back side of the liquid-impermeable sheet 11, giving the product's outer surface a cloth-like appearance. The nonwoven fabric can be used as a single layer or in multiple layers. In the latter case, it is preferable to bond the nonwoven fabrics together with a hot melt adhesive or the like. When using nonwoven fabric, the fineness of its constituent fibers should be 1.6 to 2.3 dtex and the basis weight 15 to 25 g / m². ２ Preferably, the nonwoven fabric has a thickness of 0.3 to 0.8 mm. The outer nonwoven fabric 12 can be omitted.

[0037] (Side Flap Portion) The disposable diaper of the tape type shown in the figure has a pair of side flap portions SF that extend laterally from both side edges of the absorber 56 and do not have the absorber 56. The side flap portions SF can be formed using the portions of the constituent sheets of the tape type disposable diaper that are located laterally of the absorber 56. For example, the side flap portions SF can be formed by joining a plurality of layers of sheets located laterally of the absorber 56 in the thickness direction with a hot melt adhesive or the like. Alternatively, a dedicated sheet for forming the side flap portions SF may be added laterally of the absorber 56 to form the side flap portions SF.

[0038] (Raised Gather) In order to prevent excrement that travels laterally on the top sheet 30 from leaking, so-called lateral leakage, it is preferable to provide raised gathers 60 that rise from the surface along the excrement blocking position on both sides in the width direction WD of the surface.

[0039] More specifically, this raised gather 60 has a root portion 65 fixed to the region including the side flap portion SF, a main portion 66 extending from the root portion, a front倒伏portion 67f and a rear倒伏portion 67b formed by fixing the front end portion and the rear end portion of the main portion 66 in a倒伏state, respectively, and a raised portion 68 formed by making the portion between the front倒伏portion 67f and the rear倒伏portion 67b in the main portion 66 non-fixed. Further, a gather elastic member 63 is attached to at least the tip portion of the raised portion 68.

[0040] Each part of the rising gather 60 in the illustrated example is formed by a gather sheet 62. The gather sheet 62 is folded in half at the tip of the main part 66 (the end opposite to the root part 65 side), so that the range in the width direction WD from the main part 66 to the root part 65 has a two-layer structure. The gather elastic member 63 is sandwiched between the layers of this two-layer structure part. The gather elastic member 63 can be provided only on the rising part 68, but it is preferable that it is fixed from the rear end part in the front-laying part 67f to the front end part in the rear-laying part 67b, because the contraction force of the gather elastic member 63 acts not only over the entire rising part 68 but also up to the end parts of the front-laying part 67f and the rear-laying part 67b.

[0041] The inner surface of the gather sheet 62 has a joining start end in the width direction WD on the side part of the top sheet 30, and the part on the outer side in the width direction from this joining start end is joined to the inner surface of each side flap part SF, that is, in the illustrated example, to the side part of the liquid-impermeable sheet 11 and the side part of the exterior non-woven fabric 12 located on the outer side in its width direction by a hot melt adhesive or the like.

[0042] Although the part on the inner side in the width direction from the joining start end of the rising gather 60 is fixed on the top sheet 30 at both end parts in the product front-rear direction, the rising part 68 between them is a non-fixed free part. Therefore, as the rising part 68 rises while contracting in the front-rear direction by the contraction force of the gather elastic member 63, it becomes extensible in the front-rear direction and comes into close contact with the body surface. Also, as the rising part 68 contracts in the front-rear direction by the contraction force of the gather elastic member 63, the part having the front-laying part 67f and the rear-laying part 67b is deformed so as to approach each other.

[0043] Although not shown, as is well known, the main part 66 of the rising gather 60 can be folded in half in a state having a base end side part extending from the outer side part in the width direction to the inner side in the width direction and a tip end side part folded back from the edge on the center side in the width direction of this base end side part to the body side and extending to the outer side in the width direction, and the both end parts in the front-rear direction of the main part 66 can be fixed to form a laying part.

[0044] The type of gathered sheet 62 is not particularly limited, but in most cases, a water-repellent material is used to ensure liquid barrier properties. In particular, nonwoven fabrics having meltblown layers between spunbond layers (SMS nonwoven fabric, SMMS nonwoven fabric, SSMS nonwoven fabric, SSMMS nonwoven fabric) are preferred because they can achieve both a pleasant feel and liquid barrier properties. The nonwoven fabric can be used as a single sheet or in multiple layers. In the latter case, it is preferable to bond the nonwoven fabrics together with a hot melt adhesive or the like.

[0045] As the gathered elastic member 63, a rubber thread (spandex rubber thread with a thickness of approximately 420 to 1120 dtex) can be used. As shown in Figures 1 and 2, multiple gathered elastic members 63 can be provided, or one can be provided. The elongation rate of the gathered elastic member 63 in the unfolded state can be determined as appropriate, but for example, it can be set to approximately 230 to 270%.

[0046] (Flat Gather) A side elastic member 64, made of an elongated elastic material such as elastic thread, is fixed to each side flap portion SF in an extended state along the front-rear direction LD, thereby configuring the leg portion of each side flap portion SF as a flat gather. As shown in the illustrated example, the side elastic member 64 can be provided between the gather sheet 62 and the liquid-impermeable sheet 11 at the widthwise outer side near the starting end of the joining portion of the gather sheet 62, or it can be provided between the liquid-impermeable sheet 11 and the outer nonwoven fabric 12 in the side flap portion SF. As shown in the illustrated example, multiple side elastic members 64 can be provided on each side, or only one can be provided on each side.

[0047] The flat gather is the part where the contraction force of the side elastic member 64 acts (in the figure, the part where the side elastic member 64 is shown). Therefore, in addition to the form in which the side elastic member 64 exists only in the flat gather area, there is also a structure in which the side elastic member 64 exists in front of the flat gather, behind it, or on both sides thereof, but the side elastic member 64 is finely cut in one or more places outside the flat gather area, or is not fixed to the sheet sandwiching the side elastic member 64, or both, so that the contraction force does not act on the parts other than the flat gather (essentially equivalent to not providing an elastic member), and the contraction force of the side elastic member 64 acts only on the flat gather area.

[0048] (Wing portion) In this tape-type disposable diaper, the dorsal portion B has a wing portion WP that extends outward in the width direction WD from the crotch portion M. Similarly, the ventral portion F also has a wing portion WP that extends outward in the width direction WD from the crotch portion M. These wing portions WP can also be formed from a different material from the other parts. However, in a structure having a side flap portion SF as shown in the illustrated example, it is preferable that the wing portion WP is formed by cutting the middle of the front-to-back direction LD on the side of the side flap portion SF, thereby forming a concave edge from the side edge of the crotch portion M to the lower edge of the wing portion, and as a result the wing portion WP is formed, because it facilitates manufacturing.

[0049] (Connecting Tape) As shown in Figures 1, 2, and 5, the wing portion WP of the dorsal portion B is provided with connecting tapes 13 that are detachably connected to the outer surface of the ventral portion F. When putting on the diaper, the connecting tapes 13 are wrapped around the outer surface of the ventral portion F from both sides of the waist, and the connecting portion 13A of the connecting tapes 13 is connected to the appropriate place on the outer surface of the ventral portion F.

[0050] As shown in Fig. 5, the connecting tape 13 includes a sheet base material 13S forming a base end portion 13C fixed to the wing portion WP and a main body portion 13B extending from the base end portion 13C, and a connecting portion 13A provided at an intermediate portion in the width direction WD of the main body portion 13B of the sheet base material 13S for the ventral portion F. In the main body portion 13B, the side closer to the base end portion 13C than the connecting portion 13A is a non-connecting portion not connected to the ventral portion F, and the opposite side is a gripping portion. These non-connecting portion and gripping portion are composed only of the sheet base material 13S forming the main body portion 13B.

[0051] The connecting portion 13A is made of a hook material (male material) of a mechanical fastener (surface fastener). The hook material has a large number of engaging protrusions on its connecting surface. As the shape of the engaging protrusions, there are (A) L-shaped, (B) J-shaped, (C) mushroom-shaped, (D) T-shaped, (E) double J-shaped (a shape formed by joining J-shaped ones back to back), etc., and any shape may be used.

[0052] As the sheet base material 13S forming from the base end portion 13C to the main body portion 13B, non-woven fabric, plastic film, poly la mi non-woven fabric, paper, or a composite material thereof can be used.

[0053] In the illustrated example, the connecting portion 13A is provided on the sheet base material 13S of the connecting tape 13 protruding from the wing portion WP, but it may be provided directly on the wing portion WP.

[0054] (Target Sheet) A target sheet 12T is provided at the connecting portion of the connecting tape 13 in the ventral portion F.

[0055] The material of the target sheet 12T is not particularly limited. When the connecting portion 13A is a hook material, for example, a long fiber non-woven fabric in which fibers are partially welded to each other by ultrasonic welding in an intermittent pattern can be used. In this case, it is preferable that the long fiber non-woven fabric is a non-woven fabric having a fiber fineness of 5 to 10 dtex, a basis weight of 25 to 40 g / m ２ , and a thickness of 0.3 to 0.8 mm.

[0056] Furthermore, if the connecting portion 13A is a hook material, the target sheet 12T can be made of a base material made of plastic film or nonwoven fabric with many loop threads on its surface that allow the engaging projections of the hook material to entangle. A specific example of this is a composite sheet material in which loop pile fibers are sewn onto at least the outer surface of the base material. In this sheet material, loop pile fibers are projected at intervals in the weft direction on the outer surface of the base material, i.e., the outer surface side of the disposable diaper, and on the back side of the base material (the wearer side), the pile fibers are interlocked, forming rows of intersecting pile fiber diameter threads.

[0057] Furthermore, if the connecting portion 13A is a hook material, and the connection point of the connecting tape 13 in the ventral portion F is made of nonwoven fabric (for example, if there is an outer nonwoven fabric 12 as shown in the illustrated example), a target sheet 12T made of plastic sheet, paper, nonwoven fabric, etc., on which the connection position such as a scale is printed can be placed inside the outer nonwoven fabric 12. In this case, the user can connect the parts by entangling the hook material of the connecting portion 13A with the fibers of the outer nonwoven fabric 12 at the position of the target sheet 12T, which is visible through the outer nonwoven fabric 12.

[0058] On the other hand, if the connecting portion 13A is an adhesive layer, the target sheet 12T can be a plastic film with a smooth surface that is highly adhesive, which has been subjected to a release treatment.

[0059] (End flap portion) This tape-type disposable diaper has a pair of end flap portions EF that extend to the front and rear sides of the absorbent body 56, respectively, and do not have the absorbent body 56. The end flap portions EF can be formed using the portions of the constituent sheets of the tape-type disposable diaper that are located on the front and rear sides of the absorbent body 56. For example, the end flap portions EF can be formed by joining multiple layers of sheets located on the front and rear sides of the absorbent body 56 from among the top sheet 30, intermediate sheet 40, gather sheet 62, liquid impermeable sheet 11, the stretchable sheet 70 described later, and outer nonwoven fabric 12 in the thickness direction with a hot melt adhesive or the like. Unlike the illustrated example, if at least one of the intermediate sheet 40, stretchable sheet 70, and outer nonwoven fabric 12 is not provided, the end flap portions EF can be formed using sheets other than those shown. Alternatively, a dedicated sheet for forming the end flap portions EF may be added to the front or rear side of the absorbent body 56 to form the end flap portions EF.

[0060] The front-to-back LD dimension of the end flap portion EF in the dorsal portion B is preferably longer than the front-to-back LD dimension of the base end portion 13C of the connecting tape 13. In most cases, the front-to-back LD dimension of the end flap portion EF is preferably about 20-25% of the total length L of the diaper (the total front-to-back LD dimension), and for example, in the case of infant diapers, it can be about 80-120 mm.

[0061] (Waist Elastic Member) As shown in Figures 1, 2, 4 and 7 to 10, it is preferable that a waist elastic member 71 is fixed to the end flap portion EF. The portion having this waist elastic member 71 is contracted together with the waist elastic member 71 in its natural length state, and becomes a waist stretchable region 79 that can be stretched on both sides in the width direction WD when worn. By stretching the waist stretchable region 79 when worn, the end flap portion EF can be fitted to the body surface. The portion having the waist elastic member 71 may be entirely a waist stretchable region 79, or only a part of it may be a waist stretchable region 79. That is, the portion having the waist elastic member 71 may have the elasticity of a part of the waist elastic member 71 (for example, both ends in the width direction) reduced by a known method such as cutting. As can be seen from this, the waist stretchable region 79 is a region that circumsects the portion of the waist elastic member 71 in which the elasticity has not been reduced.

[0062] The waist elastic member 71 is not particularly limited as long as it is made of a material that is elastic and stretchable on its own. For example, in addition to elongated elastic materials such as threads or strings (for example, spandex thread elastic with a thickness of about 420 to 1120 dtex), mesh-like, perforated or non-perforated film-like elastic materials, stretchable nonwoven fabrics, etc. can be used as appropriate.

[0063] When an elongated elastic material is used as the waist elastic member 71, it is preferable that, as shown in the illustrated example, the structure comprises a plurality of elongated waist elastic members 71 extending in the width direction WD and spaced apart in the front-rear direction LD, a first sheet layer 73 adjacent to the front side of the waist elastic member 71, and a second sheet layer 74 adjacent to the back side of the waist elastic member 71.

[0064] The first sheet layer 73 and the second sheet layer 74 are not particularly limited and can also be used as other components constituting the end flap portion EF (for example, the top sheet 30 and the liquid-impermeable sheet 11). However, as shown in the illustrated example, dedicated first sheet layer 73 and second sheet layer 74 can also be provided. In other words, in the illustrated example, an expandable sheet 70 in which a waist elastic member 71 is fixed between the dedicated first sheet layer 73 and second sheet layer 74 is attached to the end flap portion EF. Various nonwoven fabrics can be used as the dedicated first sheet layer 73 and second sheet layer 74.

[0065] The first sheet layer 73 and the second sheet layer 74 may be two separate sheets as shown in Figure 9, or they may be one side and the other side of a fold in a single sheet that has been folded in half as shown in Figure 15.

[0066] The arrangement and number of elastic members 71 can be determined as appropriate. For example, 5 to 15 elastic members 71 can be provided at intervals d1 of 3 to 10 mm in the front-rear direction LD. As shown in the illustrated example, it is preferable that the position of the front edge of the waist stretching region 79 (the foremost waist elastic member 71) and the position of the rear edge of the absorber 56 are spaced apart in the front-rear direction LD, because this prevents the rear end of the absorber 56 from contracting in the width direction WD.

[0067] The elongation rate of the elastic member 71 in the unfolded state can be determined as appropriate. For example, the elongation rate of the elastic member 71 in the unfolded state can be set to approximately 160 to 230%.

[0068] The first sheet layer 73 and the second sheet layer 74 can be joined continuously in both the front-rear direction LD and the width direction WD, as well as intermittently in at least one of the directions (joint portion 75). Furthermore, the fixing portion 76 for fixing the waist elastic member 71 to the first sheet layer 73 and the second sheet layer 74 only needs to be provided at at least both ends of the waist elastic member 71.

[0069] Preferably, the joint 75 between the first sheet layer 73 and the second sheet layer 74 is provided linearly and continuously or intermittently from in front of the foremost waist elastic member 71 to behind the rearmost waist elastic member 71. As a result, when the waist expansion / contraction region 79 is contracted, as shown in Figures 8 to 10, the first sheet layer 73 and the second sheet layer 74 in the non-jointed portion 77 expand in opposite directions to each other, and a continuous fold 80 is repeatedly formed in the width direction WD from in front of the waist expansion / contraction region 79 to behind the waist expansion / contraction region 79.

[0070] The width 75w of the joint 75 (the dimension in the direction perpendicular to the locus (tangent in the case of a curve) of points equidistant from both side edges of the joint 75) is preferably constant, but may change. If the width 75w of the joint 75 changes, the maximum width is preferably 2 to 5 times the minimum width. The width 75w of the joint 75 can be determined as appropriate, but if it is too wide, the breathability will decrease, and if it is too narrow, the elasticity will decrease due to peeling of the joint 75, reducing leak prevention. Therefore, it is usually preferable that it is 0.5 to 2 mm. In addition, the spacing 77w in the width direction WD of the non-jointed portion 77 in the unfolded state determines the height of the fold 80, and is usually preferably 4 to 8 mm.

[0071] The fixing portion 76 of the waist elastic member 71 is not particularly limited as long as the first sheet layer 73 and the second sheet layer 74 contract together with the waist elastic member 71 to form a waist stretchable region 79. For example, if there is a joint portion 75 that intersects with the waist elastic member 71, as shown in the examples in Figures 8 and 9, the joint portion 75 of the first sheet layer 73 and the second sheet layer 74 that intersects with the waist elastic member 71 may also serve as the fixing portion 76 of the waist elastic member 71. Also, as shown in Figure 10, if the waist elastic member 71 and the joint portion 75 do not intersect, fixing portions (not shown) may be provided only at both ends of the waist stretchable region 79, separate from the joint portion 75.

[0072] The joining of the first sheet layer 73 and the second sheet layer 74 at the joint 75, and the fixing of the waist elastic member 71 at the fixing part 76, can be carried out by known methods such as hot melt adhesive, heat sealing, ultrasonic sealing, or other welding means. The joint 75 may be a portion where the first sheet layer 73 and the second sheet layer 74 are directly joined, or the first sheet layer 73 and the second sheet layer 74 may be indirectly joined via the waist elastic member 71.

[0073] The stretchable sheet 70 can be sandwiched between appropriate components between the top sheet 30 and the outer nonwoven fabric 12 (in the illustrated example, it is between the top sheet 30 and the intermediate sheet 40 and the liquid-impermeable sheet 11, but it may also be between the liquid-impermeable sheet 11 and the outer nonwoven fabric 12), or it can be attached as the uppermost layer located on the skin side or the lowermost layer located on the back side. When the stretchable sheet 70 is positioned on the skin side, in the part with the gathered sheet 62, the stretchable sheet 70 is positioned above the gathered sheet 62 (i.e., the entire sheet becomes the uppermost layer), or it can be positioned between the top sheet 30 and the gathered sheet 62.

[0074] The joining pattern between the expandable sheet 70 and the end flap portion EF that overlaps it can be determined as appropriate. For example, the expandable sheet 70 and the end flap portion EF that overlaps it can be joined continuously in both the front-rear direction LD and the width direction WD, or they can be joined continuously in at least one of the front-rear direction LD and the width direction WD. If the joining between the expandable sheet 70 and the end flap portion EF that overlaps it (top sheet 30, etc.) is continuous in the width direction WD, then, as shown in Figure 8, the pleats 80 formed on the expandable sheet 70 and the pleats 81 formed on the front and back surfaces of the waist expansion region 79 will correspond.

[0075] <Regarding the Alignment Mark Printing Area and Backside Printing Area> Alignment mark printing areas 21 to 25 are printed on the surface (skin side) of the liquid-impermeable sheet 11, which are used to align the position of the product with the wearer's body. These alignment mark printing areas 21 to 25 are provided on at least one of the side flap area SF and end flap area EF, which do not have an absorbent material 56 and extend outward from the outer edge of the absorbent material 56, so that they can be seen from the inside of the product. Furthermore, in order to prevent the liquid-impermeable sheet 11 from being exposed on the surface, the side flap area SF and end flap area EF are covered by a front cover member (consisting of one or more layers such as a top sheet 30, intermediate sheet 40, gather sheet 62, and stretchable sheet 70) located on the front side of the liquid-impermeable sheet 11, so that the alignment mark printing areas 21 to 25 are visible through the front cover member.

[0076] To improve the visibility of the alignment mark printing sections 21-25, it is preferable that the back surface printing sections 91-95 are printed on the back surface of the liquid-impermeable sheet 11 in the flap portion such that 50% or more of the area of ​​the alignment mark printing sections 21-25 overlaps in the thickness direction. That is, if the back surface printing sections 91-95 are printed on the back surface of the liquid-impermeable sheet 11, and the alignment mark printing sections 21-25 are printed on the surface of the liquid-impermeable sheet 11 such that 50% or more of the area overlaps with the back surface printing sections 91-95, the color of the overlapping portion 20 between the alignment mark printing sections 21-25 and the back surface printing sections 91-95 will appear darker when viewed from the surface of the tape-type disposable diaper by the user than if only the alignment mark printing sections 21-25 were printed, thus improving the visibility of the alignment mark printing sections 21-25. This means that even if the alignment mark printing sections 21-25 have the same color, the presence or absence of the reverse side printing sections 91-95 will result in differences in the perceived shade of color for the user. In other words, if the visibility is the same, it also means that the printing of the alignment mark printing sections 21-25 themselves can be made lighter, thus increasing the freedom of printing.

[0077] Of the area of ​​the alignment mark printing sections 21 to 25, the ratio of the area of ​​the overlapping portion with the reverse printing sections 91 to 95 (the portion having a colored ink layer) can be appropriately determined as long as it is 50% or more, but is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. The alignment mark printing sections 21 to 25 and the reverse printing sections 91 to 95 refer to portions where colored ink is continuously applied or formed as a group of dots (a collection of minute dots) to form a specific shape for positioning, etc.

[0078] The relative sizes and overlaps of the alignment mark printing sections 21-25 and the reverse printing sections 91-95 can be determined as appropriate. For example, as shown in Figure 12, the entirety of the reverse printing sections 91 and 92 may be included within the alignment mark printing sections 21 and 22, or conversely, as shown in Figure 13, the entirety of the alignment mark printing section 23 may be included within the reverse printing section 93, or as shown in Figures 14 and 16, parts of the alignment mark printing sections 24 and 25 may overlap with parts of the reverse printing sections 94 and 95, while the remaining parts do not overlap. However, if the back-side printing sections 91-95 extend beyond the outer edges of the alignment mark printing sections 21-25, the visible shape of the alignment mark printing sections 21-25 may appear different from the printed shape of the alignment mark printing sections 21-25 (due to the protruding portion of the back-side printing sections 91-95). To avoid this, it is preferable that the entire back-side printing sections 91-92 be included within the alignment mark printing sections 21-22. Furthermore, the center or center of gravity of the alignment mark printing sections 21-25 and the center or center of gravity of the back-side printing sections 91-95 may overlap or be offset in the thickness direction.

[0079] Elements that affect the visibility of the alignment mark printing sections 21-25 on the surface of the tape-type disposable diaper can be appropriately selected, such as the color of the alignment mark printing sections 21-25 and the back-side printing sections 91-95, the liquid-impermeable sheet 11, and the front-side cover material. For example, it is preferable to select elements that affect the visibility of the alignment mark printing sections 21-25 on the surface of the tape-type disposable diaper such that the brightness L* value of the overlapping portion 20 between the alignment mark printing sections 21-25 and the back-side printing sections 91-95 is 80 or less, and the brightness L* value around the overlapping portion 20 between the alignment mark printing sections 21-25 and the back-side printing sections 91-95 is 85 or more. On the surface of the tape-type disposable diaper, the brightness L* value of the overlapping portion 20 between the alignment mark printing section 21-25 and the back printing section 91-95 is more preferably 75 or less, and particularly preferably 70 or less. On the surface of the tape-type disposable diaper, the brightness L* value around the overlapping portion 20 between the alignment mark printing section 21-25 and the back printing section 91-95 is more preferably 90 or more, and particularly preferably 95 or more.

[0080] The a* and b* values ​​of the overlapping portion 20 between the alignment mark printing sections 21-25 and the back printing sections 91-95 on the surface of the tape-type disposable diaper are not particularly limited. From the viewpoint of preventing the alignment mark printing sections 21-25 from being mistaken for blood or stains, the a* value is preferably -60 to +1. Also, the b* value is preferably -60 to 0.

[0081] The brightness L* value of the portion of the surface of the tape-type disposable diaper where the liquid-impermeable sheet 11 does not have printing is preferably greater than 90, and more preferably greater than 95. Furthermore, the a* value of the portion of the surface of the tape-type disposable diaper where the liquid-impermeable sheet 11 does not have printing is preferably between -60 and 0. Also, the b* value is preferably between -60 and 0. The color of the portion of the surface of the tape-type disposable diaper where the liquid-impermeable sheet 11 does not have printing can be white.

[0082] The L*, a*, and b* values ​​of lightness refer to the L*, a*, and b* values ​​of lightness in the "Colorimetry - Part IV: CIE 1976 L*a*b* color space" as defined in JIS Z 8781-4:2013. The L*, a*, and b* values ​​of lightness can be determined using, for example, the "NF333 SPECTRO PHOTOMETER" measuring device manufactured by Nippon Denshoku Industries, and if necessary, the portion containing the target area can be removed by cutting or peeling to create a test specimen. For example, when measuring the brightness L* value of the overlapping portion 20 between the alignment mark printing section 21-25 and the back printing section 91-95 on the surface of a tape-type disposable diaper, a test piece is cut from the tape-type disposable diaper so as to include the overlapping portion 20 between the alignment mark printing section 21-25 and the back printing section 91-95, and the measurement of the overlapping portion 20 between the alignment mark printing section 21-25 and the back printing section 91-95 is performed as is (i.e., without peeling off the front cover member or back cover member).

[0083] The visibility of the alignment mark printing areas 21-25 on the surface of the tape-type disposable diaper is also affected by the opacity of the unprinted areas of the liquid-impermeable sheet 11, the opacity of the front cover member (consisting of one or more layers such as a top sheet 30, intermediate sheet 40, gather sheet 62, and stretchable sheet 70) in the area having the alignment mark printing areas 21-25, and the opacity of the back cover member (outer nonwoven fabric 12 in the illustrated example) in the area having the alignment mark printing areas 21-25. The liquid-impermeable sheet 11 generally has an opacity of 20-60% or a whiteness of 85% or more in the unprinted areas, but from the viewpoint of visibility of the alignment mark printing areas 21-25, an opacity of 40-50% in the unprinted areas is more preferable. In conjunction with or independently of this, the opacity of the front cover member is preferably 15-30%, and more preferably 15-25%. Furthermore, with or without regard to these opacities, the opacity of the back cover member is preferably 20-40%, and more preferably 20-30%. Note that opacity refers to the value measured in accordance with JIS P8149:2000 "Paper and cardboard - Test method for opacity (backing of paper) - Diffuse illumination method".

[0084] The opacity of the liquid-impermeable sheet 11 can be changed, for example, by the amount of pigment such as titanium dioxide in the film material, or by the amount of particles such as calcium carbonate to add breathability. In addition, the opacity of the front cover member and the back cover member can be changed by the number of sheets laminated for the front cover member and the back cover member, the basis weight of each sheet, the amount of pigment such as titanium dioxide, etc.

[0085] One method to improve the visibility of the alignment mark printing sections 21-25 on the surface is to provide the alignment mark printing sections 21-25 in areas of the front cover member with a small number of sheet layers, for example, in areas with three layers or less. For example, Figure 15 shows an overview of the number of sheet layers in the tape-type disposable diaper of this example. In Figure 15, the first region A1 is an area where the number of sheet layers of the front cover member is one layer (only the single layer portion of the gather sheet 62), the second region A2 is an area where the number of sheet layers of the front cover member is two layers (the top sheet 30 and the single layer portion of the gather sheet 62), the third region A3 is an area where the number of sheet layers of the front cover member is three layers (the first sheet layer 73 and the second sheet layer 74 of the stretchable sheet 70, and the single layer portion of the gather sheet 62), and the fourth region A4 is an area where the number of sheet layers of the front cover member is four or more layers. As can be seen from this figure, in the tape-type disposable diaper of this example, there are many areas in the side flap portion SF with three or fewer sheet layers. Therefore, as shown in the illustrated example, it is preferable that the liquid-impermeable sheet 11 in the first region A1, second region A2, and third region A3 (particularly the first region A1 and second region A2) of the side flap portion SF has alignment mark printing sections 21-25 and back surface printing sections 91-95 printed on it. In particular, it is preferable that 70% or more of the overlapping portion 20 of the alignment mark printing sections 21-25 and back surface printing sections 91-95 is located within the first region A1, and more preferably 90% or more. The first region A1, second region A2, and third region A3 of the side flap portion SF are the parts that extend out to both sides of the wearer's body when an absorbent article is placed under the wearer's buttocks, and are suitable for positioning the tape-type disposable diaper in the width direction WD.

[0086] Furthermore, as shown in Figure 1, if the alignment mark printing area 22 is located in a stretchable area that shrinks in its natural length state (in this case, the waist stretchable area 79), a portion of the alignment mark printing areas 21-25 will be hidden within the shrinkage wrinkles, thus worsening the visibility of the alignment mark printing areas 21-25 before wearing. Therefore, it is preferable that 50% or more, more preferably 70% or more, and especially preferably 90% or more of the alignment mark printing areas 21-25 are located outside the flat gathers or the waist stretchable area 79.

[0087] The alignment mark printing sections 21-25 are not particularly limited in shape as long as they can indicate the position of the printed portion, and can be appropriately selected from circles, triangles, squares, stars (as shown in the example), arrows, or letters, pictures, etc. If multiple alignment mark printing sections 21-25 are provided, they may be the same shape and color, or at least one of the shapes and colors of some or all of the alignment mark printing sections 21-25 may be different. In the example shown in Figure 1, etc., with the tape-type disposable diaper placed under the wearer's buttocks, a first alignment mark printing section 21 (star-shaped in the example) is provided to indicate the position of the tape-type disposable diaper in the width direction WD relative to the wearer's body, and a second alignment mark printing section 22 (rectangle with a long side along the front-to-back direction LD in the example) is provided to indicate the center of the tape-type disposable diaper in the width direction WD. In addition to this, or instead, as shown in Figure 16, a third alignment mark printing section 25 (in the illustrated example, a triangle with its vertex located at the center of the front-to-back LD and its base aligned with the front-to-back LD) can also be provided to indicate the center of the front-to-back LD of the tape-type disposable diaper.

[0088] The dimensions of the alignment mark printing sections 21 to 25 and the dimensions of the overlapping section 20 can be determined as appropriate as needed. For example, in the case of a shape where the lengths of the front-to-back LD and the width WD are equal or close, such as the first alignment mark printing section 21 and the third alignment mark printing section 25, the dimension of the front-to-back LD can be set to about 5 to 20 mm, and the dimension of the width WD can be set to about 0.5 to 1.5 times the dimension of the front-to-back LD. Also, in the case of a shape that is long in the front-to-back LD or width WD, such as the second alignment mark printing section 22, the dimension in the longitudinal direction can be set to about 20 to 40 mm, and the dimension in the direction perpendicular to the longitudinal direction can be set to about 0.1 to 0.6 times the dimension in the longitudinal direction. Furthermore, the dimension of the overlapping section 20 in the front-to-back LD can be set to about 2.5 to 18 mm, and the dimension of the overlapping section 20 in the width WD can be set to about 0.25 to 18 mm.

[0089] The shape of the reverse printing sections 91-95 is not particularly limited as long as they overlap with 50% or more of the area of ​​the alignment mark printing sections 21-25, and can be appropriately selected from circles, triangles, squares, stars (as shown in the example), arrows, or characters, pictures, etc., that can indicate position. The reverse printing sections 91-95 may have the same shape as the alignment mark printing sections 21-25, or they may have a different shape. The reverse printing sections 91-95 may have the same color as the alignment mark printing sections 21-25, or they may have a different color. If multiple reverse printing sections 91-95 are provided, they may have the same shape and color, or at least one of the shapes and colors of some or all of the reverse printing sections 91-95 may be different.

[0090] As an example, in the example shown in Figure 1, a circular back-side printing section 91 is provided with a star-shaped first alignment mark printing section 21, with its center of gravity approximately coinciding with it. A rectangular back-side printing section 92 is provided with a rectangular second alignment mark printing section 22, with its longer side aligned in the same direction. In the example shown in Figure 16, a rectangular back-side printing section 95 is provided with a triangular third alignment mark printing section 25, and the combined outer shape of the two forms an arrow shape. In the example shown in Figure 14, an inverted triangular back-side printing section 94 of the same dimensions is provided with a triangular alignment mark printing section 24, and the combined outer shape of the two forms a hexagram shape.

[0091] When multiple alignment mark printing sections 21-25 are provided, it is not necessary to provide back-side printing sections 91-95 that overlap with 50% or more of the area of ​​the alignment mark printing sections 21-25 for all of them. For example, for some alignment mark printing sections 21-25 where visibility is good even without back-side printing sections 91-95 due to a small number of layers of sheets constituting the front cover member, back-side printing sections 91-95 that overlap with 50% or more of the area of ​​the alignment mark printing sections 21-25 may be omitted. Conversely, for alignment mark printing sections 21-25 where improved visibility is desired due to a large number of layers of sheets constituting the front cover member, back-side printing sections 91-95 that overlap with 50% or more of the area of ​​the alignment mark printing sections 21-25 may be provided.

[0092] The back-side printing sections 91-95 may be added specifically to improve the visibility of the alignment mark printing sections 21-25. However, since the back surface of the liquid-impermeable sheet 11 has registration marks for transport control of the liquid-impermeable sheet 11 and decorative patterns printed on it, these may be provided so as to overlap with 50% or more of the area of ​​the alignment mark printing sections 21-25, thereby functioning as the back-side printing sections 91-95. In particular, since registration marks are similar to the alignment mark printing sections 21-25 in that simple shapes are suitable, it is preferable to use the back-side printing sections 91-95 for both registration marks for transport control of the liquid-impermeable sheet 11 and the like, as this improves not only the visibility of the alignment mark printing sections 21-25 but also the detectability of the registration marks on the back surface of the tape-type disposable diaper.

[0093] The elements that affect the visibility of the back-side printed areas 91-95 on the back of the tape-type disposable diaper can be selected as appropriate. For example, it is preferable to select the elements that affect the visibility of the back-side printed areas 91-95 on the back of the tape-type disposable diaper such that the brightness L* value of the overlapping portion 20 between the alignment mark printed areas 21-25 and the back-side printed areas 91-95 on the back of the tape-type disposable diaper is 80 or less, and the brightness L* value around the overlapping portion 20 between the alignment mark printed areas 21-25 and the back-side printed areas 91-95 is greater than 90, as this improves the visibility of the alignment mark printed areas 21-25. It is more preferable that the brightness L* value of the overlapping portion 20 between the alignment mark printed areas 21-25 and the back-side printed areas 91-95 on the back of the tape-type disposable diaper is 75 or less, and particularly preferable that it is 70 or less.

[0094] The a* and b* values ​​of the overlapping portion 20 between the alignment mark printing sections 21-25 and the back surface printing sections 91-95 on the back surface of the tape-type disposable diaper are not particularly limited. From the viewpoint of preventing the alignment mark printing sections 21-25 from being mistaken for blood or stains, the a* value is preferably -60 to +1. Also, the b* value is preferably -60 to 0.

[0095] The brightness L* value of the portion of the back surface of the tape-type disposable diaper that does not have printing on the liquid-impermeable sheet 11 is preferably greater than 90, and more preferably greater than 95. Furthermore, the a* value of the portion of the back surface of the tape-type disposable diaper that does not have printing on the liquid-impermeable sheet 11 is preferably between -60 and 0. Also, the b* value is preferably between -60 and +2. The color of the portion of the back surface of the tape-type disposable diaper that does not have printing on the liquid-impermeable sheet 11 can be white.

[0096] <Visibility Confirmation Test> A liquid-impermeable sheet sample 1 was prepared, having a star-shaped alignment mark printing area 21 as shown in Figure 12(a) and no back-side printing area; a liquid-impermeable sheet sample 2 was prepared, having a circular back-side printing area 91 as shown in Figure 12(b) and no alignment mark printing area; and a liquid-impermeable sheet sample 3 was prepared, having a star-shaped alignment mark printing area 21 and a circular back-side printing area 91 that overlaps it (the entire area being contained within the alignment mark printing area 21) as shown in Figure 12(c).

[0097] The opacity of the unprinted areas of these liquid-impermeable sheet samples 1 to 3 was 47%, the whiteness W was 87%, the L* value was 95, the a* value was -0.03, and the b* value was 1.48. The opacity was measured using the "PF7000" measuring device manufactured by Nippon Denshoku Industries, the whiteness W was measured using the "NF333 SPECTRO PHOTOMETER" measuring device manufactured by Nippon Denshoku Industries in accordance with JIS P 8148 "Test method for whiteness of paper and cardboard by diffuse illumination (ISO whiteness)", and the L*, a*, and b* values ​​were measured by placing the test piece on a test stand and measuring with the "NF333 SPECTRO PHOTOMETER" from above the test stand toward the top surface of the test piece (the same applies below). Furthermore, the whiteness W of the test bench surface was 85%, the L* value was 94, the a* value was 0.06, and the b* value was 0.41.

[0098] Additionally, as a gathered sheet sample, we have a fineness of 2.0 dtex and a basis weight of 2.6 g / m. ２ S layer, fineness 0.4 dtex, basis weight 5.2 g / m ２ M layer, fineness 2.0 dtex, basis weight 5.2 g / m２ A nonwoven fabric with an SS layer (two S layers) was prepared. The opacity of this nonwoven fabric was 21%, the whiteness W was 82%, the L* value was 93, the a* value was 0.05, and the b* value was 0.1.

[0099] Then, liquid-impermeable sheet samples 1 to 3 were placed on the test stand, and under the following conditions: no cover on top (1), one gathered sheet sample on top (2), two gathered sheet samples on top (3), and three gathered sheet samples on top (4), the printing area (alignment mark printing area for liquid-impermeable sheet sample 1, back surface printing area for liquid-impermeable sheet sample 2, and alignment mark printing area for liquid-impermeable sheet sample 3) was printed from above. The whiteness W, L*, a*, and b* values ​​were measured in the areas having overlapping portions of the printed areas on the reverse side (the same applies below), and in the unprinted areas (areas without alignment mark printing and reverse side printing). The visibility of the printed areas was also evaluated by the tester with the naked eye on a three-point scale (○: superior visibility compared to the standard, △: no difference from the standard, ×: inferior visibility compared to the standard). This measurement and evaluation was performed for both the front surface and back surface of the liquid-impermeable sheet sample.

[0100] Table 1 shows the measurement results for each sample under each condition.

[0101] From a comparison of liquid-impermeable sheet sample 1 and liquid-impermeable sheet sample 3 in Table 1, it was found that the visibility of the printed area can be improved not only by providing a positioning mark printing area, but also by adding a reverse printing area that overlaps with it. Furthermore, in all samples, the L value of the printed area tended to increase by approximately 5 to 10 for each layer of gathered sheet sample added. However, in liquid-impermeable sheet sample 3, regardless of the layering configuration, such as having 1 to 3 layers of nonwoven fabric such as a gathered sheet on top of the liquid-impermeable sheet, as in an actual diaper, the L value of the printed area measured from above remained 80 or less, demonstrating good visibility.

[0102] <Explanation of Terms in the Specification> Unless otherwise specified in the specification, the following terms in this specification have the following meanings:

[0103] - "Front-to-back (vertical) direction" refers to the direction connecting the ventral (front) side and the dorsal (back) side, and "width direction" refers to the direction perpendicular to the front-to-back direction (left-to-right direction). - "Front side" refers to the side of the absorbent item that is closer to the wearer's skin when worn, and "back side" refers to the side of the absorbent item that is further away from the wearer's skin when worn. - "Surface" refers to the side of the material that is closer to the wearer's skin when the absorbent item is worn, and "back side" refers to the side of the material that is further away from the wearer's skin when the absorbent item is worn.

[0104] "Elongation rate" refers to the value when the natural length is set to 100%.

[0105] "Grade weight" is measured as follows: After pre-drying the sample or test piece, leave it in a test room or apparatus under standard conditions (temperature 20±5°C, relative humidity 65% ​​or less) until it reaches a constant weight. Pre-drying means bringing the sample or test piece to a constant weight in an environment with a relative humidity of 10-25% and a temperature not exceeding 50°C. Note that pre-drying is not necessary for fibers with an official moisture content of 0.0%. Using a 200mm × 250mm (±2mm) basis plate, cut a sample measuring 200mm × 250mm (±2mm) from the test piece that has reached a constant weight. Measure the weight of the sample and calculate the weight per square meter to obtain the grade weight.

[0106] - "Thickness" was measured using an automatic thickness measuring instrument (KES-G5 Handy Compression Measurement Program) with a load of 0.098 N / cm. ２ , and pressure area: 2 cm ２ Automatic measurement is performed under these conditions.

[0107] The amount of water absorbed will be measured according to JIS K7223-1996 "Test method for the amount of water absorbed by superabsorbent polymers".

[0108] Unless otherwise specified, the tests and measurements shall be conducted in a test room or apparatus under standard conditions (temperature 20±5°C, relative humidity 65% ​​or less).

[0109] The above example is an application example for tape-type disposable diapers, but the present invention can be used for all absorbent articles, such as pant-type disposable diapers, pad-type disposable diapers, and sanitary napkins.

[0110] 11...Liquid impermeable sheet, 12...Outer nonwoven fabric, 20...Overlapping portion, 21-25...Alignment mark printing portion, 21...First alignment mark printing portion, 22...Second alignment mark printing portion, 25...Third alignment mark printing portion, 30...Top sheet, 40...Intermediate sheet, 50...Absorbing element, 56...Absorbent body, 58...Packaging sheet, 60...Rising gather, 62...Gather sheet, 71...Waist elastic member, 73...First sheet layer, 74...Second sheet layer, 75...Joint portion, 76...Fixing portion, 79...Waist stretching region, 80...Pleats, 91-95...Backside printing portion, A1...First region, A2...Second region, A3...Third region, A4...Fourth region, EF...End flap portion, LD...Front-to-back direction, SF...Side flap portion, WD...Width direction.

Claims

1. An absorbent article comprising an absorbent body, a liquid-permeable top sheet disposed on the front side of the absorbent body, and a liquid-impermeable sheet disposed on the back side of the absorbent body, and further comprising a flap portion extending outward from the outer peripheral edge of the absorbent body and having no absorbent body, wherein the flap portion comprises the liquid-impermeable sheet and a front cover member covering the front side of the liquid-impermeable sheet, wherein an alignment mark printing portion is printed on the surface of the liquid-impermeable sheet in the flap portion, and a back printing portion is printed on the back side of the liquid-impermeable sheet in the flap portion such that 50% or more of the area of ​​the alignment mark printing portion overlaps.

2. The absorbent article according to claim 1, wherein the brightness L* value of the overlapping portion between the alignment mark printing portion and the back surface printing portion on the surface of the absorbent article is 80 or less, and the brightness L* value of the area surrounding the overlapping portion between the alignment mark printing portion and the back surface printing portion is 85 or more.

3. The absorbent article according to claim 1 or 2, wherein the printed area on the back is a registration mark printed on the back of the liquid-impermeable sheet.

4. The absorbent article according to claim 1 or 2, wherein the alignment mark printing area is printed so as to include the entirety of the reverse side printing area.

5. The absorbent article according to claim 1 or 2, wherein the flap portion has a back cover member that covers the back side of the liquid-impermeable sheet, the opacity of the front cover member is 15 to 30%, the opacity of the unprinted portion of the liquid-impermeable sheet is 20 to 60%, and the opacity of the back cover member is 20 to 40%.

6. The absorbent article according to claim 1 or 2, comprising a crotch portion including the center in the front-to-back direction, an abdominal portion extending forward from the center in the front-to-back direction, and a dorsal portion extending backward from the center in the front-to-back direction, wherein the absorbent body is provided in the area including the crotch portion, the flap portion includes side flap portions extending laterally from both side edges of the absorbent body in the dorsal portion, connecting portions are provided on both sides of the dorsal portion which are detachably connected to the outer surface of the abdominal portion, the side flap portion of the dorsal portion has a portion of the front cover member consisting of three or fewer sheet layers, and the alignment mark printing portion and the back printing portion are printed on the liquid-impermeable sheet in the portion of the side flap portion of the dorsal portion where the front cover member consists of three or fewer sheet layers.

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