阅读说明：本技术 吸收性物品 (Absorbent article ) 是由 古川勉 于 2019-03-19 设计创作，主要内容包括：提供一种吸收性物品,其能够提高除臭物质与臭气的接触效率。上述课题通过如下的吸收性物品得到了解决,其具有：吸收体(56)；和覆盖吸收体(56)的外侧的不透液性树脂膜(11),其特征在于,在比不透液性树脂膜(11)靠外侧的部件上直接附着有纤维素纳米纤维层(15),纤维素纳米纤维层(15)能够与吸收性物品的外部的气氛中的臭气接触。(Provided is an absorbent article which can improve the efficiency of contact between a deodorizing substance and an odor. The above problem is solved by an absorbent article comprising: an absorber (56); and a liquid-impermeable resin film (11) that covers the outside of the absorbent body (56), wherein a cellulose nanofiber layer (15) is directly attached to a member that is on the outside of the liquid-impermeable resin film (11), and the cellulose nanofiber layer (15) can come into contact with odors in the atmosphere outside the absorbent article.)

1. An absorbent article having:

an absorbent body; and

a liquid-impermeable resin film covering the outside of the absorbent body,

it is characterized in that the preparation method is characterized in that,

a cellulose nanofiber layer is directly attached to a member on the outer side of the liquid impermeable resin film,

the cellulose nanofiber layer is capable of coming into contact with an odor in an atmosphere outside the absorbent article.

2. The absorbent article according to claim 1,

the absorbent article has an outer-covering nonwoven fabric covering the outer surface of the liquid-impermeable resin film,

the cellulose nanofiber layer is interposed between the liquid-impermeable resin film and the exterior nonwoven fabric,

the nonwoven fabric has a fiber fineness of 1.0 to 6.0dtex and a fiber basis weight of 15g/m²～45g/m²The thickness is 0.5 mm-3.0 mm.

3. The absorbent article according to claim 1 or claim 2,

the absorbent article has: a ventral portion located more anterior than the center in the anterior-posterior direction; and a back side portion located more rearward than the center in the front-rear direction,

the absorbent article has a post-treatment belt protruding from both side portions of the back-side section or protruding from a widthwise intermediate portion of the back-side section,

the cellulose nanofiber layer is disposed at the dorsal portion, and the cellulose nanofiber layer is not disposed at the ventral portion.

4. The absorbent article according to any one of claims 1 to 3,

the cellulose nanofiber layer is provided only in a range overlapping with the absorbent body.

5. The absorbent article according to any one of claims 1 to 4,

the absorbent article has an outer-covering nonwoven fabric covering the outer surface of the liquid-impermeable resin film,

the cellulose nanofiber layer is provided at a plurality of locations with a space in at least one of a front-back direction and a width direction between the liquid-impermeable resin film and the exterior nonwoven fabric, and is directly attached to at least the liquid-impermeable resin film,

the liquid-impermeable resin film and the exterior nonwoven fabric are bonded together by a hot-melt adhesive at a portion not having the cellulose nanofiber layer,

a part or the whole of each of the cellulose nanofiber layers is not covered with the hot melt adhesive.

6. The absorbent article according to any one of claims 1 to 5,

the average fiber width of the cellulose nanofibers of the cellulose nanofiber layer is 10nm to 100nm,

the cellulose nano-fiber layer is composed of 0.1g/m²～5.0g/m²The cellulose nanofibers of (1).

Technical Field

The present invention relates to an absorbent article such as a disposable diaper such as a pants-type diaper or a tape-type diaper, or a sanitary napkin.

Background

Generally, absorbent articles such as disposable diapers and sanitary napkins are used in such a form that: after use, the excrement is rolled or folded so that the surface to which the excrement adheres becomes the inside, and the excrement is put into a highly airtight storage container such as a sanitary box or a diaper storage container for temporary storage, and when the amount of the excrement stored in the container reaches a certain level, the excrement is put into a garbage bag and discarded. The absorbent article after use produces a strong odor of excrement, which causes discomfort to the user. Therefore, in order to suppress the odor of excrement after use, the following proposals have been made: disposing a deodorizing sheet containing zeolite on the inner side of the top sheet (patent document 1); alternatively, a crepe paper covering the absorber is made to contain a deodorant (patent document 2).

Disclosure of Invention

Problems to be solved by the invention

However, since a general solid deodorant substance does not have adhesiveness, it is necessary to use a fixing means such as a hot melt adhesive or an adhesive in order to reliably fix the deodorant substance to an absorbent article. In this case, there is not only a problem that the cost for the fixing means is increased, but also the following problem: since a part or the whole of the deodorizing particles is covered with the fixing means, the efficiency of contact with the odor is lowered.

Therefore, the main object of the present invention is to improve the efficiency of contact between a deodorizing substance and an odor.

Means for solving the problems

Various types of absorbent articles that solve the above problems are as follows.

< the invention as described in claim 1 >)

An absorbent article having: an absorbent body; and a liquid-impermeable resin film covering the outside of the absorbent body, wherein a cellulose nanofiber layer is directly attached to a member on the outside of the liquid-impermeable resin film, and the cellulose nanofiber layer can be in contact with odor in the atmosphere outside the absorbent article.

(Effect)

The present inventors have found, in the course of intensive studies to solve the above problems: the cellulose nanofiber layer has sufficient adhesiveness and has an effect of reducing odor by physically adsorbing odor. The present invention has been made based on this finding, and a cellulose nanofiber layer is directly attached to a member on the outer side of a liquid-impermeable resin film (this means that the attachment is performed only by the adhesiveness of cellulose nanofibers without using an adhesive or the like). Therefore, the cellulose nanofiber layer has a high contact efficiency with odor, and can effectively reduce odor outside the absorbent article, and particularly, can effectively reduce odor inside the storage container when the absorbent article is placed in the storage container and temporarily stored. Patent documents 3 and 4 describe inventions in which cellulose nanofibers are applied to absorbent articles, but these documents do not aim at reducing odor.

< the invention as described in claim 2 >)

The absorbent article according to claim 1, wherein the absorbent article has an outer-covering nonwoven fabric covering an outer surface of the liquid-impermeable resin film, the cellulose nanofiber layer is interposed between the liquid-impermeable resin film and the outer-covering nonwoven fabric, and the outer-covering nonwoven fabric is provided on the outer-covering nonwoven fabricThe nonwoven fabric has a fiber fineness of 1.0 to 6.0dtex and a fiber basis weight of 15g/m²～45g/m²The thickness is 0.5 mm-3.0 mm.

(Effect)

The portion having the cellulose nanofiber layer inevitably becomes hard, so that there is a concern that the feel of the outer surface of the absorbent article is felt hard. Therefore, it is preferable that the cellulose nanofiber layer is covered with the relatively thick and strong exterior nonwoven fabric as described above, whereby the hardness of the cellulose nanofiber layer is not easily transmitted, and deterioration of the texture of the outer surface of the absorbent article is suppressed.

< the invention as described in claim 3 >)

The absorbent article according to claim 1 or claim 2, wherein the absorbent article has: a ventral portion located more anterior than the center in the anterior-posterior direction; and a back side portion located more to the rear side than the center in the front-rear direction, the absorbent article having a post-treatment belt protruding from both side portions of the back side portion or protruding from a widthwise intermediate portion of the back side portion, the cellulose nanofiber layer being provided in the back side portion, and the cellulose nanofiber layer not being provided in the stomach side portion.

(Effect)

Absorbent articles widely adopt such a form at the time of disposal: the post-treatment tape is fixed to the outer surface of the absorbent article in a state where the absorbent article is rolled or folded so that the inner surface of the absorbent article is positioned inside. In such a state when discarded, as shown in fig. 12, the outer surface of the absorbent article is covered with the back portion, and odor generated from excrement attached to the inner surface of the absorbent article or excrement absorbed by the absorber passes through the back portion of the outer surface and is released to the outside. Accordingly, if the cellulose nanofiber layer is provided on the back side portion, the cellulose nanofiber layer is positioned in the main path of the odor in the disposal state in which the absorbent article is rolled or folded, and therefore the effect of reducing the odor can be exerted more effectively. In addition, in the disposal form in which the absorbent article is rolled or folded, the cellulose nanofiber layer is located closer to the outer surface, and therefore, even for odor existing outside the article, such as odor in the storage container, the odor reducing effect can be exerted. In addition, by adopting such a structure, even if the cellulose nanofiber layer is not provided over the entire portion outside the liquid-impermeable resin film, the odor reduction effect can be effectively exhibited, and therefore, the cost-effectiveness ratio is excellent.

< the invention as described in claim 4 >)

The absorbent article according to any one of claims 1 to 3, wherein the cellulose nanofiber layer is provided only in a range overlapping with the absorbent body.

(Effect)

The portion having the cellulose nanofiber layer may be inevitably hardened. The hardness of the cellulose nanofiber layer is hidden by the cushioning properties of the absorbent body in the region overlapping the absorbent body on the skin side of the wearer. However, in a portion having no absorber, the hardness concealing effect by the absorber cannot be expected. Therefore, the cellulose nanofiber layer is preferably provided only in a range overlapping with the absorbent body.

< the invention as described in claim 5 >)

The absorbent article according to any one of claims 1 to 4, wherein the absorbent article has an outer-covering nonwoven fabric covering an outer surface of the liquid-impermeable resin film, the cellulose nanofiber layer is provided at a plurality of locations with a space in at least one of a front-back direction and a width direction between the liquid-impermeable resin film and the outer-covering nonwoven fabric, and is directly attached to at least the liquid-impermeable resin film, the liquid-impermeable resin film and the outer-covering nonwoven fabric are bonded together by a hot-melt adhesive at a portion not having the cellulose nanofiber layer, and a part or the whole of each of the cellulose nanofiber layers is not covered with the hot-melt adhesive.

(Effect)

In view of the adhesiveness of the cellulose nanofiber layer, the efficiency of contact with external odor, and the skin touch on the outer surface, it is preferable that the cellulose nanofiber layer is adhered to the outer surface of the liquid-impermeable resin film and the outer side thereof is covered with the exterior nonwoven fabric. Here, the outer-covering nonwoven fabric and the liquid-impermeable resin film are bonded together with a normal hot-melt adhesive. However, in order to improve the efficiency of contact between the cellulose nanofiber layer and the odor, it is not preferable to coat the cellulose nanofiber layer with a hot-melt adhesive. In contrast, if the structure is formed as described above: it is preferable that the cellulose nanofiber layer is provided at a plurality of positions with a space therebetween, the liquid-impermeable resin film and the exterior nonwoven fabric are bonded together at the space, and a part or the whole of each of the cellulose nanofiber layers is not covered with the hot-melt adhesive, because the reduction in the contact efficiency between the cellulose nanofiber layer and the odor can be suppressed even when the exterior nonwoven fabric and the liquid-impermeable resin film are bonded together.

Further, since the cellulose nanofiber layer is hard, if it is continuously provided over a wide range, flexibility of the product may be impaired. On the other hand, if the cellulose nanofiber layers are provided at intervals, the flexibility can be suppressed from being lowered even if the cellulose nanofiber layers are provided over a wide range. On the other hand, the cellulose nanofibers adsorb odor by physical adsorption. In addition, since the cellulose nanofibers are fibrous, they have a high aspect ratio and a relatively large specific surface area. Therefore, since cellulose nanofibers have better physical adsorption than general deodorant particles, the effect of reducing odor is large even if cellulose nanofiber layers are provided at intervals. In addition, since the amount of cellulose nanofibers to be used can be reduced, the cost-to-efficiency ratio is also excellent.

< the invention as set forth in claim 6 >

The absorbent article according to any one of claims 1 to 5, wherein the cellulose nanofibers of the cellulose nanofiber layer have an average fiber width of 10nm to 100nm, and the cellulose nanofiber layer is composed of 0.1g/m²～5.0g/m²The cellulose nanofibers of (1).

(Effect)

The average fiber width and the amount of the cellulose nanofibers to be used are not particularly limited, but are preferably within the above ranges in a usual case.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an absorbent article having improved contact efficiency between a deodorizing substance and an odor is provided.

Drawings

Fig. 1 is a plan view showing the inner surface of a tape-type disposable diaper in a state where the diaper is unfolded.

Fig. 2 is a plan view showing the outer surface of the tape-type disposable diaper in a state where the diaper is unfolded, and is a view showing an application part of the cellulose nanofiber layer.

Fig. 3 is a cross-sectional view taken along line 6-6 of fig. 1.

Fig. 4 is a cross-sectional view taken along line 7-7 of fig. 1.

Fig. 5 is a cross-sectional view taken along line 8-8 of fig. 1.

Fig. 6 is a cross-sectional view taken along line 9-9 of fig. 1.

Fig. 7 is a cross-sectional view taken along line 5-5 of fig. 1.

Fig. 8 is a sectional view showing an important part.

Fig. 9 is a sectional view showing an important part.

Fig. 10 is a sectional view showing an important part.

Fig. 11 is a plan view showing the outer surface of the tape-type disposable diaper in a state where the diaper is unfolded, and is a view showing an application part of the cellulose nanofiber layer.

Fig. 12 is an explanatory view of a disposable diaper in a discarded state.

Detailed Description

After the wearer excretes, the belt-type diaper is wrapped in such a manner that the excretion is not visible from the outside and is discarded. As an example of disposal methods, a diaper is rolled up in a substantially cylindrical shape (disposal form) so that the inner surface thereof is inward in the back-and-belly direction (see fig. 12 (a)). Even if the excrement is wrapped in a substantially cylindrical shape in this way, the odor of the excrement is diffused to the outside of the substantially cylindrical shape. Therefore, a diaper having an improved efficiency of contact between a deodorizing substance and an odor is proposed below.

Fig. 1 to 7 show an example of a tape-type disposable diaper, in which the reference numeral X indicates the full width of the diaper except for a connecting tape, the reference numeral L indicates the entire length of the diaper, and a dotted part in a cross-sectional view indicates an adhesive as a joining means for joining the respective components located on the inner and outer surfaces thereof, and the adhesive is formed by full-surface application of a hot-melt adhesive, linear (ビード) application, curtain (カーテン) application, critical portion (サミット) application or spiral application, pattern application (transfer of a hot-melt adhesive by a relief printing method), or the like, or a fixing part of an elastic member is formed by application to the outer peripheral surface of the elastic member by an application gun, a size application, or the like, instead of or together with the adhesive. Examples of the hot melt adhesive include EVA adhesives, adhesive rubber adhesives (elastic adhesives), olefin adhesives, and polyester polyamide adhesives, and can be used without particular limitation. As a joining means for joining the respective constituent members, a material-based welding means such as heat sealing or ultrasonic sealing may be employed.

The tape-type disposable diaper comprises: an absorber 56; a liquid-permeable top sheet 30 covering the inner surface of the absorber 56; a liquid-impermeable resin film 11 that covers the outer surface of the absorbent body 56; and an outer-covering nonwoven fabric 12 which covers the outer surface of the liquid-impermeable resin film and constitutes the outer surface of the product. Reference numeral F denotes a ventral portion located forward from the center in the front-rear direction, and reference numeral B denotes a dorsal portion located rearward from the center in the front-rear direction.

Hereinafter, the materials and the characteristic portions of each portion will be described in order.

(absorber)

The absorber 56 is a portion that absorbs and holds excretory fluid, and may be formed of an aggregate of fibers. As the fiber aggregate, in addition to an aggregate obtained by stacking short fibers such as cotton pulp or synthetic fibers, acetate fibers may be used as neededA filament (filament) aggregate obtained by opening a tow (fiber bundle) of synthetic fibers such as cellulose. The basis weight of the fibers may be, for example, about 100 to 300g/m in the case of stacking cotton pulp or short fibers²In the case of the filament aggregate, the amount of the filament aggregate may be, for example, about 30 to 120g/m². The fineness of the synthetic fiber is, for example, 1 to 16dtex, preferably 1 to 10dtex, and more preferably 1 to 5 dtex. In the case of the filament assembly, the filaments may be uncrimped fibers, but crimped fibers are preferable. The crimp of the crimped fibers may be, for example, 5 to 75 crimps per 2.54 cm, preferably 10 to 50 crimps, and more preferably about 15 to 50 crimps. In addition, uniformly crimped fibers may be used.

(super absorbent Polymer particles)

The super absorbent polymer particles may be contained in a part or all of the absorbent body 56. The super absorbent polymer particles include "powder" in addition to "particles". As the super absorbent polymer particles 54, super absorbent polymer particles used in such an absorbent article can be used as they are. The particle size of the super absorbent polymer particles is not particularly limited, but is preferably a particle size of: for example, when a screen (5 minutes of vibration) using a 500 μm standard sieve (JIS Z8801-1: 2006) is performed and a screen (5 minutes of vibration) using a 180 μm standard sieve (JIS Z8801-1: 2006) is performed on particles falling below the sieve in the screen, 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.

The material of the super absorbent polymer particles is not particularly limited, but a material having a water absorption capacity of 30g/g or more is preferable. Examples of the super absorbent polymer particles include high absorbent polymer particles such as starch-based, cellulose-based, and synthetic polymer-based, and high absorbent polymer particles such as starch-acrylic acid (salt) -grafted polymer, saponified product of starch-acrylonitrile copolymer, crosslinked sodium carboxymethylcellulose, and acrylic acid (salt) -based polymer can be used. The shape of the super absorbent polymer particles is preferably a powder shape which is generally used, but other shapes may be used.

The superabsorbent polymer particles preferably have a water absorption rate of 70 seconds or less, particularly 40 seconds or less. If the water absorption rate is too slow, so-called back flow in which the liquid supplied into the absorbent body 56 returns to the outside of the absorbent body 56 tends to occur.

In addition, as the super absorbent polymer particles, it is preferable to use super absorbent polymer particles having a gel strength of 1000Pa or more. Thus, even when the absorbent body 56 is formed to be bulky, the sticky feeling after absorbing liquid can be effectively suppressed.

The basis weight of the superabsorbent polymer particles can be determined as appropriate depending on the absorption amount required for the application of the absorbent body 56. Therefore, it can be 50 to 350g/m². If the weight per unit area of the polymer is less than 50g/m²It is difficult to secure the absorption amount. If it exceeds 350g/m²Not only the effect is saturated, but also a feeling of sand discomfort is generated due to an excess of superabsorbent polymer particles.

(packaging sheet)

In order to prevent the superabsorbent polymer particles from coming off or to improve the shape retention of the absorbent body 56, the absorbent body 56 may be incorporated as an absorbent member 50 wrapped with a wrapping sheet 58. As the packaging sheet 58, a tissue paper (tissue paper), particularly, crepe paper, nonwoven fabric, polyethylene laminated nonwoven fabric, a sheet with small holes, or the like can be used. Among these, a sheet that does not cause the super absorbent polymer particles to come out is preferable. When a nonwoven fabric is used instead of crepe paper, a hydrophilic SMMS (spunbond/meltblown/spunbond) nonwoven fabric is particularly suitable, and polypropylene, polyethylene/polypropylene, or the like can be used as a material thereof. The weight per unit area of the fiber is preferably 5 to 40g/m²Particularly preferably 10 to 30g/m²。

The packaging sheet 58 may be formed by wrapping the entire absorbent body 56 with a single sheet as shown in fig. 3, or may be formed by wrapping the entire absorbent body 56 with a plurality of sheets such as 2 sheets on top and bottom. The wrapping sheet 58 may also be omitted.

(Top sheet)

The top sheet 30 is a liquid-permeable sheet, and for example, a nonwoven fabric having holes or holes, a porous plastic sheet, or the like can be used. The kind of the raw material fiber of the nonwoven fabric is not particularly limited. Examples thereof include olefin-based fibers such as polyethylene and polypropylene, synthetic fibers such as polyester and polyamide, regenerated fibers such as rayon and cuprammonium fibers, natural fibers such as cotton, and the like, and mixed fibers and composite fibers using two or more of these fibers. Further, the nonwoven fabric may be produced by any process. Examples of the processing method include known methods such as a spunlace method, a spunbond method, a hot-rolling method, a melt-blowing method, a needle-punching method, a hot-air method, and a point-bonding method. For example, the water-jet method is a preferable processing method when flexibility and drapability are sought, and the hot rolling method is a preferable processing method when bulkiness and flexibility are sought.

The top sheet 30 extends from the front end to the rear end of the product in the front-rear direction and further extends laterally than the absorbent body 56 in the width direction WD, but, for example, in the case where the starting point of the standing gather portion 60 described later is located on the widthwise central side of the side edge of the absorbent body 56, appropriate deformation such as shortening the width of the top sheet 30 from the entire width of the absorbent body 56 can be performed as necessary.

(intermediate sheet)

In order to rapidly transfer the liquid having passed through the top sheet 30 to the absorbent member, an intermediate sheet (also referred to as "second sheet") 40 having a liquid passing speed higher than that of the top sheet 30 may be provided. The intermediate sheet 40 is used for the following purposes: the liquid is rapidly moved toward the absorbent body to improve the absorption performance of the absorbent body and to prevent the phenomenon that the absorbed liquid "flows back" from the absorbent body. The intermediate sheet 40 may also be omitted.

The intermediate sheet 40 may be made of the same material as the top sheet 30, or may be made of spunlace nonwoven fabric, spunbond nonwoven fabric, SMS nonwoven fabric, pulp nonwoven fabric, a mixed sheet of pulp and rayon, point-bond nonwoven fabric, or crepe paper. The air-through nonwoven fabric is particularly bulky and is therefore preferable. For the through-air nonwoven fabric, it is preferable to use a composite fiber having a core-sheath structure, and in this case,the resin used for the core may be polypropylene (PP), but is preferably Polyester (PET) having high rigidity. The weight per unit area is preferably 17 to 80g/m²More preferably 25 to 60g/m². The thickness of the raw material fiber of the nonwoven fabric is preferably 2.0 to 10 dtex. In order to make the nonwoven fabric bulky, it is preferable to use a bias fiber, a hollow fiber, or a bias and hollow fiber having no core at the center as a mixed fiber of all or a part of the raw material fibers.

The intermediate sheet 40 in the illustrated example is shorter than the width of the absorber 56 and is disposed at the center, and may be provided over the entire width. The intermediate sheet 40 may be provided over the entire length of the diaper, but may be provided only in the intermediate portion including the excretion portion as shown in the illustrated example.

(liquid-impermeable resin film)

The liquid-impermeable resin film 11 is not particularly limited as long as it has moisture permeability, and for example, a microporous sheet obtained by the following method can be suitably used: the inorganic filler is kneaded with an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretched in a uniaxial or biaxial direction. Of course, the liquid-impermeable resin film 11 does not include a film having a nonwoven fabric as a base material and improved water resistance.

The liquid-impermeable resin film 11 preferably extends over the same or a wider range as the absorbent body 56 in the front-back direction LD and the width direction WD, but may be formed so as not to cover the end of the absorbent body 56 in the front-back direction LD and the width direction WD, if necessary, in the case where other water blocking means is present, or the like. An indicator that develops color or fades due to the liquid component of the excrement may be provided on the inner surface of the liquid-impermeable resin film 11. As the indicator, a known indicator can be used without particular limitation. For example, the indicator may be constituted by a sheet member containing: a colorant exhibiting a color reaction by contact with moisture in excrement and/or a colorant exhibiting a color reaction by detection of a pH value in moisture; or an ink or an adhesive containing a chemical that exhibits a reaction of disappearing coloring by a reaction with a liquid component of excrement, a reaction of dissolving (dispersing) a colorant into urine to permeate or disappear, or other visual changes; alternatively, a drug which shows a visual change by contact with moisture or a liquid component in excrement (indicator reaction means). As the coloring agent which exhibits a color reaction by contact with moisture in excrement, a water-soluble, water-decomposable dye, or a coloring agent composed of a leuco fuel and a color-developing agent such as a phenolic compound, an acidic substance, or an electron-accepting substance which develops a color of the leuco fuel can be used.

(nonwoven fabric for exterior application)

The outer nonwoven fabric 12 covers the entire outer surface of the liquid-impermeable resin film 11, and gives the outer surface of the product a cloth-like appearance. The outer-covering nonwoven fabric 12 is not particularly limited, and for example, synthetic fibers such as olefin-based fibers such as polyethylene and polypropylene, polyester-based fibers and polyamide-based fibers, regenerated fibers such as rayon and cuprammonium fibers, and natural fibers such as cotton can be used as the face fibers, and a spunlace method, a spunbond method, a hot-roll method, a hot-air method, a needle-punching method, and the like can be used as the processing method. However, a long fiber nonwoven fabric such as a spunbond nonwoven fabric, an SMS nonwoven fabric, and an SMMS nonwoven fabric is preferable in that both the texture and strength can be achieved. In addition to using one nonwoven fabric, a plurality of nonwoven fabrics can be used by being stacked together. In the latter case, the nonwoven fabrics are preferably bonded to each other by a hot melt adhesive or the like. In this case, it is preferable that the nonwoven fabric 12 has a fiber fineness of 1.0 to 6.0dtex and a fiber basis weight of 10 to 45g/m²The thickness is 0.1 to 3.0 mm. However, the range is not limited thereto.

In addition, in the case where the exterior nonwoven fabric 12 has the cellulose nanofiber layer 15, the portion having the cellulose nanofiber layer 15 inevitably becomes hard, and the hand feel of the outer surface of the absorbent article may be hard. Therefore, it is preferable that the cellulose nanofiber layer 15 is covered with the relatively thick and strong exterior nonwoven fabric 12, whereby the hardness of the cellulose nanofiber layer 15 is not easily transmitted, and deterioration of the texture of the outer surface of the absorbent article is suppressed. In this caseThe nonwoven fabric for external covering is preferably such that the fiber fineness is 1.0 to 6.0dtex and the fiber basis weight is 15 to 45g/m²The thickness is 0.5 to 3.0 mm. The outer-covering nonwoven fabric 12 having the cellulose nanofiber layer 15 is not limited to these ranges, and may be any nonwoven fabric as long as it is not likely to transmit the hardness of the cellulose nanofiber layer 15 and can suppress deterioration of the texture of the outer surface of the absorbent article.

(vertical gather part)

In order to prevent the excrement moving in the lateral direction of the top sheet 30 on the top sheet and to prevent so-called side leakage, it is preferable that standing gather portions 60 standing toward the skin side of the wearer are provided on both sides in the width direction WD of the inner surface. Of course, the gather portion 60 may be omitted.

When the raised gather portion 60 is used, the structure thereof is not particularly limited, and any known structure can be used. The raised gather portion 60 of the illustrated example is constituted by: a gather sheet 62 substantially continuous in the width direction WD; and an elongated gather portion elastic member 63 fixed to the gather sheet 62 in an extended state along the front-rear direction LD. As the gather sheet 62, a water repellent nonwoven fabric can be used, and as the gather portion elastic member 63, a rubber thread or the like can be used. As shown in fig. 1 and 2, the elastic members may be provided in 1 piece, instead of a plurality of pieces.

The inner surface of the gather sheet 62 has a joining start in the width direction WD at the side portion of the top sheet 30, and from this joining start, the portion on the outer side in the width direction is joined to the inner surface of each side flap portion SF by a hot melt adhesive or the like, that is, in the illustrated example, to the side portion of the liquid-impermeable resin film 11 and the side portion of the exterior nonwoven fabric 12 on the outer side in the width direction.

In the leg hole, the inner side in the width direction from the joining start end of the standing gather portion 60 is fixed to the top sheet 30 at both ends in the front-rear direction of the product, but the portion between both ends in the front-rear direction of the product is an unfixed free portion which stands up by the contraction force of the elastic member 63 and comes into close contact with the body surface.

(wing part, flank part)

The tape-type disposable diaper illustrated in the drawings has: a pair of end flaps EF not having the absorber 56, which project toward the front side and the rear side of the absorber 56, respectively; and a pair of side portions SF not having the absorbent body 56, which extend further laterally than both side edges of the absorbent body 56.

(Flat gather part)

In each side flap portion SF, a side elastic member 64 made of an elongated elastic member such as a rubber thread is fixed in an extended state along the front-rear direction LD, and thus the leg hole portion of each side flap portion SF is configured as a planar gather portion. The leg hole elastic members 64 may be provided between the gather sheet 62 and the liquid-impermeable resin film 11 on the outer side in the width direction in the vicinity of the joining start end of the gather sheet 62 in the joined portion as shown in the figure, or between the liquid-impermeable resin film 11 and the outer-covering nonwoven fabric 12 in the flap portion SF. The leg hole elastic members 64 may be provided only by 1 on each side, in addition to the plurality of members provided on each side as in the illustrated example.

(connecting belt)

The side wing portions SF of the back portion B are respectively provided with connecting bands 13 detachably connected to the outer surfaces of the stomach portion F. When the diaper 10 is worn, the connecting tape 13 is wound around the outer surface of the abdominal portion F from both sides of the waist, and the connecting portion 13A of the connecting tape 13 is connected to an appropriate portion of the outer surface of the abdominal portion F.

The structure of the connecting belt 13 is not particularly limited, but in the illustrated example, the connecting belt has: a sheet base material that constitutes a belt mounting portion 13C fixed to the wing portion SF and a belt body portion 13B protruding from the belt mounting portion 13C; and a connecting portion 13A connected to the ventral side, provided at a widthwise intermediate portion of the belt main body portion 13B in the sheet base material, and a portion on the distal end side of the connecting portion 13A serves as a grasping portion.

The coupling portion 13A may be provided with an adhesive layer in addition to hook members (projections) of a mechanical fastener (surface fastener). The hook piece has a plurality of engaging protrusions on its connecting surface, and the shapes of the engaging protrusions include (a) レ shape, (B) J shape, (C) mushroom shape, (D) T shape, (E) double J shape (shape in which J-shaped structures are joined back to back), and the like, but may have any shape.

The sheet base material from the belt mounting portion 13C to the belt main body portion 13B may be a nonwoven fabric, a plastic film, a polyethylene laminated nonwoven fabric, paper, or a composite material thereof, and preferably has a fineness of 1.0 to 3.5dtex and a basis weight of 20 to 100g/m²Spun-bonded nonwoven fabric, hot-air nonwoven fabric or spun-laced nonwoven fabric having a thickness of 1mm or less.

(target sheet)

Preferably, a target 20 is provided at a joining portion with the joining belt 13 in the ventral portion F, the target 20 having a target for facilitating joining. In the target 20, when the coupling portion 13A is a hook member, a target in which a plurality of loop lines to which engagement protrusions of the hook member are hooked are provided on the inner surface of a sheet base material made of a plastic film or a nonwoven fabric may be used, and when the coupling portion 13A is an adhesive material layer, a target in which a peeling process is performed on the surface of a sheet base material made of a plastic film having a smooth surface such that the adhesive property is high may be used. In the case where the connecting portion to the connecting band 13 in the stomach-side portion F is formed of a nonwoven fabric, for example, in the case where the exterior nonwoven fabric 12 is provided as shown in the figure, the target piece 20 may be omitted and the hook member may be hooked to the fiber of the exterior nonwoven fabric 12 to connect the fibers. In this case, a target sheet 20 as a mark may be provided between the exterior nonwoven fabric 12 and the liquid-impermeable resin film 11.

(cellulose nanofiber)

The cellulose nanofibers are fine cellulose fibers obtained by opening pulp fibers, and generally refer to cellulose fibers including cellulose microfibers having an average fiber width of nanometer size (1nm or more and 1000nm or less), but cellulose nanofibers having an average fiber width (median diameter) of 100nm or less are preferable, and cellulose nanofibers having an average fiber width of 10 to 100nm are more preferable. If the amount is within this range, the cellulose nanofiber layer is excellent in efficiency of contact with odor, and odor outside the absorbent article can be reduced more effectively. However, the range is not limited to this.

Cellulose fibers are mainly formed by linking numerous β -glucoses into chains by β -1,4 glycosidic bonds. Beta-glucose has an-H group, an-OH group, etc.

Here, a method for measuring the average fiber width of the cellulose nanofibers will be described.

First, 100ml of an aqueous dispersion of cellulose nanofibers having a solid content concentration of 0.01 to 0.1 mass% was filtered through a teflon (registered trademark) membrane filter, and 1-time solvent substitution was performed with 100ml of ethanol and 3-time solvent substitution was performed with 20ml of t-butanol.

Subsequently, freeze-drying was performed, and osmium was applied to the sample to prepare a sample. The sample was observed at any magnification of 5000 times, 10000 times, and 30000 times (in this example, 30000 times) according to the width of the fiber to be formed, and the observation was performed based on an electron microscope SEM image. Specifically, two diagonal lines are drawn in the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Further, a total of 100 fiber rods crossing the three straight lines were visually measured. Then, the median diameter (median diameter) of the measured values was taken as the average fiber width. Further, not limited to the median diameter of the measured value, for example, the number average diameter or the mode diameter (the diameter with the highest frequency) may be used as the average fiber diameter.

Examples of pulp fibers that can be used for producing cellulose nanofibers include: chemical pulp such as hardwood pulp (LBKP), softwood pulp (NBKP), and the like; mechanical pulp such as bleached thermomechanical pulp (BTMP), groundwood pulp (SGP), pressure groundwood Pulp (PGW), Refined Groundwood Pulp (RGP), Chemical Groundwood Pulp (CGP), high Temperature Groundwood Pulp (TGP), Groundwood Pulp (GP), thermomechanical pulp (TMP), chemical thermomechanical pulp (CTMP), disc groundwood pulp (RMP), etc.; waste paper pulp manufactured by waste tea paper, blind craft envelope paper, waste magazine paper, waste newspaper, waste leaflet paper, office paper, waste corrugated paper, waste white paper, Kent paper, imitated paper, ground ticket paper, waste grass paper and the like; and deinked pulp (DIP) obtained by deinking waste paper pulp. These pulps may be used alone or in combination of two or more kinds as long as the effects of the present invention are not impaired. Further, a material obtained by subjecting the pulp fiber to chemical treatment such as carboxymethylation may be used.

Examples of the method for producing cellulose nanofibers include mechanical methods such as a high-pressure homogenization method, a micro-jet method, a grinding method by a grinder, a freeze-pulverization method, and an ultrasonic fiber-opening method, but are not limited to these methods. In addition, the nanofiber formation is promoted by the combined use of TEMPO oxidation treatment, phosphorylation treatment, acid treatment, and the like.

As shown in fig. 8 to 10, a cellulose nanofiber layer 15 can be provided between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12. Note that, in fig. 8 to 10, reference numeral H denotes an adhesive such as a hot melt adhesive for bonding the liquid impermeable resin film 11 and the exterior nonwoven fabric 12, and the liquid impermeable resin film 11 and the exterior nonwoven fabric 12 may be bonded together by fusion bonding or the like of materials, as described above. When such a cellulose nanofiber layer 15 is provided between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12, odor of excrement that has passed through the liquid-impermeable resin film 11 is adsorbed by the cellulose nanofiber layer 15. By this adsorption, the concentration of the odor decreases as the odor passes through the cellulose nanofiber layer 15. Further, when a wearer of the tape-type disposable diaper wears clothes on the outside of the diaper, excess odor temporarily released to the outside of the diaper accumulates on the inside of the clothes, and is again adsorbed by the cellulose nanofiber layer 15 of the diaper. This further reduces the concentration of odor diffusing to the outside of the diaper.

In addition, moisture is not blocked by the cellulose nanofiber layer 15, and therefore, the moisture resistance during wearing is not easily lowered. Further, since the cellulose nanofibers have high moisture absorption, moisture is retained in the cellulose nanofiber layer 15, and the outer surface of the product or the underwear is less likely to feel wet.

The cellulose nanofiber layer 15 is not necessarily provided between the liquid-impermeable resin film 11 and the outer-covering nonwoven fabric 12, and may be provided in a region that encloses the absorbent body 56 from the outside when the diaper is formed in a disposal form (substantially cylindrical form) as shown in fig. 12. For example, in the case where the exterior nonwoven fabric 12 is not arranged, it may be provided on the outer surface of the liquid-impermeable resin film 11. Excrement is present in the absorbent body or the liquid-permeable top sheet 30. If the cellulose nanofiber layer 15 is provided on the liquid-impermeable resin film 11 or the outer-covering nonwoven fabric 12 disposed on the outer surface side of the absorbent body 56 or the liquid-permeable top sheet 30, the liquid-impermeable resin film 11 or the outer-covering nonwoven fabric 12 surrounds excrement when the absorbent body is formed into a waste form (substantially cylindrical form). Therefore, the diffusion of odor to the outside can be reduced.

Disposal of the tape-type disposable diaper after use is performed as follows, for example. The diaper is removed from the wearer and wound from the abdomen-side end edge toward the back-side end edge while being rolled so that the inner surface of the diaper becomes the inner side of the wound diaper. After the completion of the winding, the connecting tape 13 extending outward in the width direction is fixed to the outer nonwoven fabric 12 (the outer surface side of the diaper) so as not to loosen the diaper roll. Thus, as shown in fig. 12 (a), the diaper has a substantially cylindrical shape. When the diaper is tightly rolled up without a gap (the number of times of rolling is large), the substantially cylindrical form is formed relatively thin, and the area of the side surface 91 of the substantially cylindrical form is relatively small. On the other hand, when the diaper tape is wound with a gap (the number of winding times is small), the substantially cylindrical shape is formed relatively thick, and the area of the side surface 91 of the substantially cylindrical shape is relatively large. Further, as an example of disposal of the diaper, there is also an example of disposal as follows. In a state where the diaper is unfolded, the diaper is wound so as to be rolled up from the abdomen-side end portion to the back-side end portion, and after the diaper is wound up to the back-side end portion, the connecting tape 13 extending outward in the width direction is fixed to the exterior nonwoven fabric 12 (the outer surface side of the diaper) so as not to loosen the diaper roll. However, the disposal method is various depending on the guardian, and is not limited to the above. When the post-treatment tape 71 is present projecting from both side portions of the back-side portion of the diaper or projecting from the widthwise intermediate portion of the back-side portion, the following configuration is widely adopted: when disposal, the post-treatment tape is fixed to the outer surface of the diaper in a state where the diaper is rolled or folded so that the inner surface of the diaper becomes the inside.

The number of winding times varies from person to person depending on the guardian. Therefore, the range in which the cellulose nanofiber layer 15 is provided is not particularly limited, and may be a range in which the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12 overlap. In addition, when the post-treatment tape 71 or the connection tape 13 is on the back side of the outer surface of the diaper, the length Y of the cellulose nanofiber layer 15 in the front-back direction LD may be a length from the edge on the back side of the diaper to the center of the diaper. The length Y is preferably 1/2, more preferably 1/3, and still more preferably 1/4 of the entire length L of the diaper. When the cellulose nanofiber layer 15 is provided in this range, the side surface 91 (i.e., corresponding to the cylindrical side surface 91) of the diaper in the substantially cylindrical form is surrounded by the cellulose nanofiber layer 15. When the post-treatment tape 71 or the connecting tape 13 is positioned on the front side of the outer surface of the diaper, the length Y of the cellulose nanofiber layer 15 in the front-rear direction LD may be set to a length from the edge on the front side of the diaper to the center of the diaper.

In addition, it may be: the cellulose nanofiber layer 15 is also provided over the entire outer surface of the connecting tape 13 or a part thereof. In this way, the two substantially cylindrical bottom surfaces 92 and 92 are also completely surrounded by the cellulose nanofiber layer 15, and thus the odor is effectively reduced. The cellulose nanofiber layer 15 may be provided on all or part of the wing portion SF. However, the cellulose nanofiber layer 15 is not limited to the above, and may not be provided in the connecting belt 13 or the side flap portion SF depending on the use of the absorbent article.

Disposal of a pants-type disposable diaper is performed as follows, for example. The diaper is removed from the wearer. A pants-type disposable diaper is folded in advance so that the back side and the ventral side are aligned. The diaper is wound up in a direction from the center portion of the outer surface toward the abdomen-side end edge, and after the winding is completed, the post-treatment tape 71 provided on the back-side outer surface is stretched in a direction toward the back-side end edge and fixed to the outer surface of the outer-cover nonwoven fabric 12 (the outer surface of the diaper) so as not to loosen the diaper roll. Thus, as shown in fig. 12 (b), the diaper has a substantially cylindrical shape.

The inventor finds that: the cellulose nanofiber layer 15 has sufficient adhesiveness itself, and has an effect of physically adsorbing odor to reduce odor. When the cellulose nanofiber layer 15 is interposed between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12, the cellulose nanofiber layer 15 can come into contact with odor in the atmosphere outside the disposable diaper. Therefore, the cellulose nanofiber layer 15 has a high contact efficiency with odor, and can effectively reduce odor outside the disposable diaper, and particularly, can effectively reduce odor in a storage container when the disposable diaper is stored in the storage container temporarily.

For example, disposable diapers and the like adopt such usage forms: after use, the excrement is rolled or folded to be discarded so that the surface to which the excrement adheres becomes the inside, and is temporarily stored in a highly airtight storage container such as a sanitary box or a diaper storage container. A strong odor of excrement is generated from the disposable diaper after use, resulting in a feeling of discomfort for the user.

The outer surface of the disposable diaper is covered with the back-side portion, and odor generated from excrement attached to the inner surface of the diaper or excrement absorbed by the absorber 56 is released to the outside through the back-side portion of the outer surface. If the cellulose nanofiber layer 15 is provided on the back side portion, the cellulose nanofiber layer 15 is located in the main path of odor in the disposal state in which the diaper is rolled or folded, and therefore the effect of reducing odor can be exerted more effectively. In addition, in the disposal form in which the diaper is rolled or folded, the cellulose nanofiber layer 15 is located closer to the outer surface, and therefore, even for odor existing outside the article, such as odor in the storage container, the odor reducing effect can be exerted.

One of the main components of the odor of excrement is methyl mercaptan (CH)₃SH). The cellulose nanofiber layer 15 adsorbs methyl mercaptan to reduce the concentration of odor of excrement. Adsorption of mainly substancesPhysical adsorption. Specifically, methyl mercaptan is adsorbed to the cellulose nanofiber layer 15 by van der waals force. In addition, cellulose nanofibers generally have a fiber width of 4nm to 1000nm, a fiber length of 5 μm or more, a high aspect ratio (5 or more in the low case and 1250 or more in the high case), a large specific surface area, and excellent physical adsorption properties.

The cellulose nanofiber layer 15 may be formed on the inner surface of the outer nonwoven fabric 12 as shown in fig. 8 (b), or the cellulose nanofiber membrane 15F may be disposed between the liquid-impermeable resin film 11 and the outer nonwoven fabric 12 as shown in fig. 9, or the sheet 16 of nonwoven fabric, paper, or the like, on which the cellulose nanofiber layer 15 is formed, may be disposed between the liquid-impermeable resin film 11 and the outer nonwoven fabric 12 as shown in fig. 10, but is preferably formed on the outer surface of the liquid-impermeable resin film 11 as shown in fig. 8 (a). Further, when the cellulose nanofiber layer 15 is applied to the liquid-impermeable resin film 11 made of a moisture-permeable resin film, the cellulose nanofibers form a film shape, and therefore, there are also the following advantages: the liquid-impermeable resin film 11 has improved odor reducing properties and strength, and reduced ductility. In particular, in the liquid-impermeable resin film 11 made of a moisture-permeable resin film, in addition to continuous decorative printing made of a plurality of constituent units such as characters (size, brand name, manufacturer name, pattern name, etc.) or patterns regularly repeated in the front-back direction LD and the width direction WD, intermittent decorative printing may be performed which is disposed only on one or both of the front and back sides of the product, such as product logos, figures, photographs, etc., but when such decorative printing is performed, it is desirable that the liquid-impermeable resin film 11 has low extensibility.

Further, when the cellulose nanofiber layer 15 is coated on the liquid-impermeable resin film 11 made of a moisture-permeable resin film, although odor reducing property and strength are improved, it becomes hard. Therefore, it is preferable to reduce the basis weight of the moisture-permeable resin film, which is the base material of the liquid-impermeable resin film 11, to, for example, 10 to 12g/m²To compensate for the reduction in flexibility. In general, the weight per unit area of the moisture-permeable resin film is reduced toAt such a level, although there is a concern that pinholes may be generated and the water-blocking property may be lowered, when the cellulose nanofiber layer 15 is coated on the moisture-permeable resin film, such lowering of the water-blocking property can be prevented and the odor reduction effect can be obtained.

In order to improve the odor reducing property, it is preferable to increase the amount of cellulose nanofibers, but if the amount is too large, the product becomes unnecessarily hard. Therefore, the cellulose nanofiber layer 15 is preferably coated in an amount of about 0.1 to 5.0g/m². Further, it is more preferably about 0.5 to 3.0g/m²。

In addition, the cellulose nanofiber layer 15 may be provided in all or a part of the range in which the cellulose nanofiber layer 15 is to be provided. In the case of being provided in a part of the range where the cellulose nanofiber layer 15 is to be provided, it is preferable to provide the cellulose nanofiber layer in a plurality of locations with intervals therebetween. For example, the cellulose nanofiber layer 15 may be provided in a vertical stripe pattern (see fig. 11). In addition, the cellulose nanofiber layer 15 may be formed in a horizontal stripe shape, a diagonal stripe shape, or a lattice shape. Even if the cellulose nanofiber layer 15 is provided at a plurality of locations with intervals in this manner, a part of the exterior nonwoven fabric 12 is difficult to be rolled up or peeled from the liquid-impermeable resin film 11 because the cellulose nanofiber layer 15 itself has adhesiveness.

In addition, it may be: the cellulose nanofiber layer 15 is provided at a plurality of locations with intervals between the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12, and is directly attached to at least the liquid-impermeable resin film 11, the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12 are bonded together by a hot melt adhesive or the like at a portion not having the cellulose nanofiber layer 15, and a part or the whole of each of the cellulose nanofiber layers 15 is not covered with the hot melt adhesive or the like. In consideration of the adhesiveness of the cellulose nanofiber layer 15, the efficiency of contact with external odor, and the skin touch on the outer surface, it is preferable that the cellulose nanofiber layer 15 is adhered to the outer surface of the liquid-impermeable resin film 11 and the outer side thereof is covered with the outer-covering nonwoven fabric 12. Here, the outer-covering nonwoven fabric 12 and the liquid-impermeable resin film 11 are bonded together with a normal hot-melt adhesive or the like. However, it is not preferable to coat the cellulose nanofiber layer 15 with a hot-melt adhesive or the like in order to improve the efficiency of contact between the cellulose nanofiber layer 15 and the odor. In contrast, if the structure is formed as described above: it is preferable that the cellulose nanofiber layer 15 is provided at a plurality of positions with a space therebetween, the liquid-impermeable resin film 11 and the exterior nonwoven fabric 12 are bonded together at the space, and a part or the whole of each of the cellulose nanofiber layers 15 is not covered with a hot-melt adhesive or the like, because the lowering of the contact efficiency of the cellulose nanofiber layer 15 with odor can be suppressed even when the exterior nonwoven fabric 12 and the liquid-impermeable resin film 11 are bonded together.

Further, since the cellulose nanofiber layer 15 is hard, if it is continuously provided over a wide range, flexibility of the product may be impaired. On the other hand, if the cellulose nanofiber layers 15 are provided at intervals, the flexibility can be suppressed from being lowered even if the cellulose nanofiber layers are provided over a wide range. On the other hand, the cellulose nanofibers adsorb odor by physical adsorption. In addition, since the cellulose nanofibers are fibrous, they have a high aspect ratio and a relatively large specific surface area. Therefore, the cellulose nanofibers have better physical adsorption than general deodorant particles, and even if the cellulose nanofiber layer 15 is disposed at intervals, the odor reduction effect is large. In addition, since the amount of cellulose nanofibers to be used can be reduced, the cost-to-efficiency ratio is also excellent.

The cellulose nanofiber layer 15 may be provided only in a range overlapping with the absorbent body 56. The portion having the cellulose nanofiber layer 15 may be inevitably hardened. This is because the hardness of the cellulose nanofiber layer 15 is hidden by the cushioning properties of the absorbent body 56 in the region overlapping with the absorbent body 56 on the skin side of the wearer.

The cellulose nanofiber layer 15 can be produced by a known method such as the following method: the cellulose nanofibers are brought into a state of a cellulose nanofiber dispersion, and the cellulose nanofiber layer is formed by applying the cellulose nanofiber dispersion to a target sheet such as a liquid-impermeable resin film 11 and drying the same. In addition, when the liquid cellulose nanofiber is applied to a fibrous sheet such as paper or nonwoven fabric by the method for producing the liquid cellulose nanofiber, the cellulose nanofiber layer 15 can be formed on the sheet by adhering the cellulose nanofiber layer to the sheet because the cellulose nanofiber is concentrated on the surface of the sheet although the liquid cellulose nanofiber penetrates into a part of the sheet. The solution for dispersing the cellulose nanofibers is not particularly limited, and a volatile organic solvent such as acetone may be used in addition to water and lower alcohols such as ethanol.

The cellulose nanofiber dispersion is obtained by dispersing cellulose nanofibers in water. The concentration (mass/volume) of the cellulose nanofiber dispersion is preferably 0.1 to 10%, more preferably 1.0 to 5.0%, and particularly preferably 1.5 to 3.0%.

The B-type viscosity (60rpm, 20 ℃) of the cellulose nanofiber dispersion is, for example, 300cps or less, preferably 200cps or less, and more preferably 50cps or less. By suppressing the B-type viscosity of the cellulose nanofiber dispersion liquid to be low in this manner, the cellulose nanofibers are uniformly applied to the sheet surface, and the surface properties of the sheet are uniformly improved.

The application of the cellulose nanofibers may be performed by a transfer method such as a relief printing method, in addition to spraying on the target surface.

Cellulose nanofibers are generally produced by decomposition of plants or the like or biosynthesis of bacteria. In addition, the structure of cellulose nanofibers is a structure obtained by polymerization of glucose, and there is no risk of harm.

< test for confirming Effect >

The effect confirmation test of 2 cellulose nanofiber layers 15 was performed. The specifications of the absorbent body 56, the liquid-impermeable resin film 11, the outer-covering nonwoven fabric 12, and the cellulose nanofibers used in these effect confirmation tests are as follows.

The absorber 56 is obtained by uniformly mixing pulp fibers and super absorbent polymer particles, and contains 180g/m²Pulp fiber of (2) and 220g/m²The superabsorbent polymer particles of (1).

As the super absorbent polymer particles, the following particles were used: the water absorption capacity was 33g/g, the water absorption rate was 35 seconds, the gel strength was 3800Pa, and when a sieve (shaking 5 minutes) using a 500 μm standard sieve (JIS Z8801-1: 2006) was performed and a sieve (shaking 5 minutes) using a 180 μm standard sieve (JIS Z8801-1: 2006) was performed on particles falling under the sieve in the sieve, the proportion of particles remaining on the 500 μm standard sieve was 18% by weight and the proportion of particles remaining on the 180 μm standard sieve was 80% by weight.

Further, the liquid-impermeable resin film 11 used therein had a weight per unit area of 18g/m²The moisture-permeable polyethylene film of (3). The moisture permeability of the liquid-impermeable resin film 11 (method under temperature and humidity condition B of JIS Z0208 (under conditions of 40 ℃ and 90% humidity)) was 9000g/m in effect confirmation test 1²24h, 9000g/m in Effect confirmation test 2²24h and 10000g/m²·24h。

Further, the exterior nonwoven fabric 12 used therein had a weight per unit area of 20g/m²The nonwoven fabric (2.0 dtex) is a core-sheath composite fiber of polyethylene (sheath) and polyethylene terephthalate (core).

The cellulose nanofibers used in the present test were cellulose nanofibers having an NBKP of 100%. Cellulose nanofibers having an average fiber width (median diameter) of 49nm were used. The cellulose nanofiber is obtained by the following steps: after NBKP was subjected to refining treatment and coarse opening, it was subjected to treatment 4 times using a high-pressure homogenizer and opened. The average fiber width is measured by the above-described method for measuring the average fiber width of the cellulose nanofibers.

< test 1 > for confirming Effect

The following sample diapers were produced, and the concentration of methyl mercaptan, which is a main component of odor of excrement, was measured. The purpose of this test was to confirm how much the concentration of methyl mercaptan was reduced in the diaper provided with the cellulose nanofiber layer 15.

(sample diaper)

The samples of diapers used in this test were as follows.

The specimen 1 was: the cellulose nanofiber layer 15 was provided between the liquid-impermeable resin film 11 and the outer nonwoven fabric 12, and no deodorant (sugarcane extract MSX-245 (manufactured by mitsui sugar corporation)) was applied.

The specimen 2 was: the cellulose nanofiber layer 15 was provided on the inner surface of the liquid-permeable top sheet 30, and a deodorant (MSX-245) was applied to the outer surface of the outer-cover nonwoven fabric 12 (diaper outer surface).

The specimen 3 is: the cellulose nanofiber layer 15 was not provided and a deodorant (MSX-245) was applied to the outer surface of the diaper.

The specimen 4 is: the cellulose nanofiber layer 15 was not provided, and a deodorant (MSX-245) was not coated.

In the specimen 1, 50g of a 0.1% cellulose nanofiber dispersion was uniformly applied to the entire outer surface of the liquid-impermeable resin film 11 and dried, thereby producing a film having a thickness of 3.0g/m²The liquid-impermeable resin film 11 of the cellulose nanofiber layer 15. The cellulose nanofibers had a NBKP of 100% and an average fiber width (median diameter) of 49 nm.

In specimen 2, 50g of a 0.1% cellulose nanofiber dispersion was uniformly applied to the entire inner surface of a liquid-permeable top sheet 30 and dried to prepare a sheet having 2.5g of a deodorant (MSX-245) and 3.0g/m²The liquid-permeable top sheet 30 of the cellulose nanofiber layer 15.

In the specimen 3, a liquid-impermeable resin film 11 having a deodorant (MSX-245) was produced by uniformly applying 50g of a solution prepared by dissolving 2.5g of the deodorant (MSX-245) in water to the entire outer surface of the liquid-impermeable resin film 11 and drying the solution.

(test operation)

50mL of methyl mercaptan at a concentration of 0.3% was injected into the center of the absorbent body 56 on the inner surface of the diaper. The diaper was placed in an air-impermeable bag, sealed and allowed to stand. After 1 hour of injection of the odorous liquid, the concentration of methyl mercaptan in the bag was measured by a test tube method. The detection tube method is as follows: 500ml of a gas as a test object was aspirated using a detection tube, and the concentration (ppm) of the object gas was measured. The detection tubes used were methylmercaptan detection tubes manufactured by GASTEC corporation under nos. 71 and 71H.

(results)

With respect to the concentration of methyl mercaptan in the odorous liquid itself, the concentration of this gas was 500ppm per 500 mL. The measurement results of the detection tube are shown in table 1.

[ Table 1]

In table 1, the odor reduction rate of methanethiol in sample n (n is any one of 1, 2, and 3) is determined by the following equation.

[ equation 1]

In the formula, the concentration of the sample 4 after 1 hour is a concentration obtained by measuring methanethiol in the bag after the sample 4 is put in the bag and sealed and left standing for 1 hour. The concentration of the sample n after 1 hour is a concentration obtained by placing the sample n in the bag, sealing the bag, and standing the bag for 1 hour, and then measuring the methanethiol in the bag.

Therefore, the following steps are carried out: in samples 1 to 3, the concentration was lower than that of sample 4, and the odor was reduced. Comparing sample 1 and sample 2, it was found that sample 1 had a higher odor reduction rate. This is explained as follows. The odor liquid dropped onto the diaper is absorbed by the absorber 56. This is because, in the sample 2, the cellulose nanofiber layer 15 is provided on the inner surface of the absorber 56, and diffusion of methyl mercaptan to the outer surface side of the absorber 56 cannot be suppressed.

Further, comparing sample 1 and sample 3, it is seen that the odor reduction rate of sample 1 is higher. Thus, it can be seen that: under the conditions of this test, the odor reduction rate of the cellulose nanofiber layer 15 was higher than that of the deodorant (MSX-245). Thus confirming that: sample 1 had a higher odor reduction rate than samples 2 and 3.

< test 2 for confirming Effect

The following sample diapers were produced, and the concentration of methyl mercaptan, which is a main component of odor of excrement, was measured. The purpose of this test was to confirm how much the concentration of methyl mercaptan was reduced in the diaper provided with the cellulose nanofiber layer 15.

(sample diaper)

The samples of diapers used in this test were as follows.

The samples were 9 samples from S1 to S9. As shown in Table 2, the moisture permeability of samples S1 to S6 was 9000g/m²Moisture permeability of samples S7-S9 was 10000g/m in 24h²24 h. In the range of 0.1 to 1.5g/m²The weight per unit area of the cellulose nanofiber layer 15 was adjusted. The cellulose nanofiber layer 15 was provided on the liquid-impermeable resin film 11 in stripes having a coating width of 5mm and coating intervals of 5mm, and the hot-melt adhesive 81 was applied only to the portions not coated with the cellulose nanofiber layer 15. The cellulose nanofibers had a NBKP of 100% and an average fiber width (median diameter) of 49 nm.

(test operation)

A liquid obtained by dissolving methyl mercaptan in water so that the concentration (mass/volume) thereof becomes 0.5% was used as the odorous liquid. 50mL of this odorous liquid was injected into the center of the absorber 56 on the inner surface of the diaper. The diaper was placed in an air-impermeable bag, sealed and allowed to stand. After 0 hour, 4 hours, and 24 hours after the odor liquid was injected, the concentration (ppm) of methyl mercaptan in the bag was measured by the test tube method (JIS K0804: 2014 test tube gas meter).

(results)

The test results are shown in table 2. In table 2, the basis weight means the basis weight (g/m) when the cellulose nanofibers are coated on the liquid-impermeable resin film 11²)。

[ Table 2]

Table 2 shows the concentration (ppm) of methyl mercaptan and the odor reduction rate (%) of methyl mercaptan measured immediately after injection (0 hour), 4 hours, and 24 hours after injection of the odorous liquid into samples S1 to S9. In table 2, the odor reduction rate (%) was obtained according to the following equation.

[ equation 2]

In the formula, the concentration of the sample S1 immediately after injection is the concentration of methyl mercaptan measured immediately after the odorant liquid is injected into the center of the absorber 56 with respect to the sample S1.

The concentration of the sample Sm after t hours is the concentration of methyl mercaptan measured after t hours has elapsed with respect to the sample Sm. m is any of 1 to 9, and t is any of 0, 4 and 24.

Focusing on the odor reduction rate after 4 hours in table 2, the samples coated with cellulose nanofibers (S2 to S9) tended to be relatively higher than the sample not coated with cellulose nanofibers (S1). In particular, samples 4 to 6 exhibited a particularly high odor reduction rate.

According to the results, the coating amount of the cellulose nanofibers is preferably 0.1g/m²The above is more preferably 0.5g/m²The above.

< description of words in the specification >)

Unless otherwise specified in the specification, the following terms in the specification have the following meanings.

"anterior-posterior (longitudinal) direction LD" means a direction connecting the ventral side (anterior side) and the dorsal side (posterior side), and means "dorsal-ventral direction" in the claims. The "width direction WD" refers to a direction (left-right direction) perpendicular to the front-back direction.

"expanded state" refers to a state of flat expansion without contraction and relaxation.

"elongation" means a value when the natural length is 100%.

"gel strength" is measured as follows. To 49.0g of artificial urine (2 wt% of urea, 0.8 wt% of sodium chloride, 0.03 wt% of calcium chloride dihydrate, 0.08 wt% of magnesium sulfate heptahydrate, and 97.09 wt% of ion-exchanged water) was added 1.0g of a super absorbent polymer, and the mixture was stirred with a stirrer. The resultant gel was allowed to stand in a constant temperature and humidity bath at 40 ℃ X60% RH for 3 hours and then returned to normal temperature, and the gel strength was measured by a curdometer-MAX ME-500 (manufactured by I.techno Engineering Co.).

"weight per unit area" was measured as follows. The sample or test piece is dried and placed in a laboratory or apparatus in a standard state (the temperature in the test site is 23. + -. 1 ℃ C., and the relative humidity is 50. + -. 2%) so as to be in a constant state. The preliminary baking means that the sample or the test piece is made constant in an environment at a temperature of 100 ℃. In addition, the fibers having a official moisture regain of 0.0% may not be subjected to preliminary drying. Using a template (100 mm. times.100 mm) for sample selection, a sample having a size of 100 mm. times.100 mm was cut out from the test piece in a constant state. The weight of the sample was measured, and the weight per square meter was calculated as a unit area weight by 10 times.

"thickness" is measured using an automatic thickness measuring apparatus (KES-G5 Portable compression tester) at a load of 0.098N/cm²The pressure area is 2cm²Is automatically measured under the conditions of (1).

"Water absorption" was measured according to JIS K7223-1996 "method for testing Water absorption of super absorbent resin".

"Water absorption Rate" is the "time to end point" when JIS K7224-1996 "Water absorption Rate test method for superabsorbent resin" was carried out using 2g of a superabsorbent polymer and 50g of physiological saline.

The test or measurement is carried out in a laboratory or apparatus in a standard state (in a test site, the temperature is 23 ± 1 ℃, and the relative humidity is 50 ± 2%) without describing the environmental conditions in the test or measurement.

The dimensions of the respective portions are not particularly described, and are dimensions in the expanded state, not the natural length state.

Industrial applicability

The present invention can be applied not only to the tape-type disposable diaper as in the above-described example, but also to all disposable diapers such as a pants-type disposable diaper and a pad-type disposable diaper, and of course, can also be applied to other absorbent articles such as a sanitary napkin.

Description of the reference symbols

11: a liquid-impermeable resin film; 12: a non-woven fabric is externally arranged; 12A: an engaging portion; 13: a connecting belt; 13A: a connecting portion; 13B: a belt main body portion; 13C: a belt mounting portion; 15: a cellulose nanofiber layer; 20: target sheet; 30: a topsheet; 40: an intermediate sheet; 56: an absorbent body; 58: packaging the sheet; 60: raising a gather portion; 62: a gusset; 71: a post-treatment zone; 86. 88 and 89: an elongated elastic member; 91: a side surface; 92: a bottom surface; b: a back side portion; f: a ventral portion; WD: a width direction; LD: the front-back direction.