CN112912045A

CN112912045A - Absorbent article

Info

Publication number: CN112912045A
Application number: CN201980067422.1A
Authority: CN
Inventors: 大村夏美; 曾我部瑶介; 黑田贤一郎; 野田祐树
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2018-11-30
Filing date: 2019-09-24
Publication date: 2021-06-04
Anticipated expiration: 2039-09-24
Also published as: KR20210098942A; TW202022187A; KR102625454B1; JP7271150B2; TWI814914B; CN112912045B; JP2019198620A; WO2020110439A1

Abstract

The invention provides an absorbent article comprising a topsheet which is less likely to cause uncomfortable irritation to the skin of a wearer and has excellent skin-contactability. In the absorbent article of the present invention, the topsheet (2) comprises: a first fiber layer (2a) containing water-retentive fibers (F)₁) And forming the skin-side surface of the surface sheet (2); and a second fiber layer (2b) containing thermoplastic resin fibers (F)₂) And water-retentive fibers (F)₁) And the non-skin side surface of the surface sheet (2) is formed adjacent to the non-skin side of the first fiber layer (2a), and the fibers of the first fiber layer (2a) are formedMiddle water-retaining fiber (F)₁) Of the fibers constituting the second fiber layer (2b), water-retentive fibers (F)₁) At least a part of the water-retentive fibers (F) contained in the first fiber layer (2a) is high₁) At the part where the fibers are interlaced with each other (P)_E) At least one part of (b) of (a)_E) Formed of the thermoplastic resin fibers (F)₂) Melt (F) of (2)_2M) And (6) covering.

Description

Absorbent article

Technical Field

The present invention relates to an absorbent article such as a sanitary napkin for a menstrual period.

Background

As a surface sheet used for an absorbent article such as a sanitary napkin for physiological use, a sheet containing water-retentive fibers that absorb and retain water such as cotton fibers is known, and for example, patent document 1 discloses a nonwoven fabric in which bleached cotton fibers (cotton fibers) to which natural oil and fat are attached and thermoplastic staple fibers in which at least the fiber surface is composed of olefin polymers are used as a surface material that can be used for an absorbent article, and the constituent fibers are three-dimensionally entangled with each other. The nonwoven fabric disclosed in patent document 1 can be applied to a field where a conventional nonwoven fabric made of defatted cotton fibers, such as a surface material of an absorbent article, cannot be used.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2005-139594

Problems to be solved by the invention

However, if only cotton fibers (water-retentive fibers) and thermoplastic short fibers (thermoplastic resin fibers) are interlaced as in the nonwoven fabric disclosed in patent document 1, when the nonwoven fabric is used as a top sheet of an absorbent article which is in direct contact with the skin in the crotch portion and the peripheral portion of a wearer (i.e., the skin of a portion where irritation is easily perceived), the thermoplastic resin fibers contained in the nonwoven fabric tend to cause uncomfortable irritation such as a stiff touch or a needle-pricked touch to the skin of the wearer, and when the absorbent article is used, the interlacing of the fibers with each other is loosened or the water-retentive fibers are broken due to friction with the skin of the wearer, so that fluffing of the water-retentive fibers occurs on the surface on the skin side of the top sheet, and uncomfortable irritation may be caused to the skin of the wearer due to the fluffing.

Disclosure of Invention

Accordingly, an object of the present invention is to provide an absorbent article including a topsheet which is less likely to cause uncomfortable irritation to the skin of a wearer and has excellent skin-contactability.

Means for solving the problems

The absorbent article of one aspect (aspect 1) of the present invention includes a topsheet, in which,

the surface sheet is provided with:

a first fiber layer containing water-retentive fibers and forming a skin-side surface of the top sheet; and

a second fiber layer that contains thermoplastic resin fibers and water-retentive fibers and that forms a surface of the topsheet on the non-skin side adjacent to the non-skin side of the first fiber layer,

constitute the proportion of the water-retaining fiber in the fiber of the first fiber layer is higher than the proportion of the water-retaining fiber in the fiber of the second fiber layer,

at least a part of the water-retentive fibers contained in the first fiber layer are covered with a melt of the thermoplastic resin fibers at an interlaced part of at least a part of interlaced parts of the fibers.

In the absorbent article of this aspect, the ratio of the water-retentive fibers of the first fiber layer in the top sheet is higher than the ratio of the water-retentive fibers of the second fiber layer, and at least a part of the thermoplastic resin fibers contained in the second fiber layer is a melt covering at least a part of the interlaced portion of the fibers contained in the first fiber layer, so even if the top sheet contains thermoplastic resin fibers, the thermoplastic resin fibers are less likely to come into contact with the skin of the wearer, and uncomfortable irritation such as a stiff touch or a needle-pricked touch to the wearer can be less likely to occur.

Further, in the absorbent article of the present aspect, since at least a part of the water-retentive fibers contained in the first fiber layer are covered with the molten material of the thermoplastic resin fibers at least a part of the interlaced portions of the fibers, the interlacing of the fibers in the surface sheet is less likely to be loosened, and the water-retentive fibers are less likely to be broken, so that fluffing of the water-retentive fibers due to the loosening of the interlacing and the breaking of the water-retentive fibers is less likely to occur, and uncomfortable irritation due to the fluffing is less likely to be caused to the wearer.

Therefore, the absorbent article of the present aspect can realize an absorbent article including a topsheet that is less likely to cause uncomfortable irritation to the skin of the wearer and that has excellent skin-contactability.

In another aspect (aspect 2) of the present invention, in the absorbent article according to aspect 1, one thermoplastic resin fiber of the thermoplastic resin fibers is interlaced with a plurality of the water-retentive fibers, and interlaced portions of the one thermoplastic resin fiber and the plurality of the water-retentive fibers are covered with a molten material of the one thermoplastic resin fiber.

In the absorbent article of this aspect, since the interlaced portions of the single thermoplastic resin fiber and the plurality of water-retentive fibers are covered with the melt of the single thermoplastic resin fiber, respectively, and the plurality of water-retentive fibers are connected to each other via the single thermoplastic resin fiber, the above-described fluffing due to the loosening of the interlaced portions and the breaking of the water-retentive fibers can be made less likely to occur.

In still another aspect (aspect 3) of the present invention, in the absorbent article according to aspect 1 or 2, the molten thermoplastic resin fibers may not be exposed on the skin-side surface of the first fiber layer.

In the absorbent article of this aspect, since the molten thermoplastic resin fibers are not exposed on the skin-side surface of the first fiber layer, the presence of the molten thermoplastic resin fibers is less likely to be perceived by the wearer, and good skin-contactability of the topsheet can be more reliably obtained.

In still another aspect (aspect 4) of the present invention, in the absorbent article according to any one of aspects 1 to 3, at least an average fiber length of the water-retaining fibers contained in the first fiber layer is shorter than an average fiber length of the thermoplastic resin fibers.

In the absorbent article of this aspect, the average fiber length of the water-retentive fibers contained in the first fiber layer is shorter than the average fiber length of the thermoplastic resin fibers contained in the second fiber layer, so that the number of water-retentive fibers in the first fiber layer in contact with one thermoplastic resin fiber contained in the second fiber layer is increased, and therefore the amount of molten thermoplastic resin fiber adhering to each of the water-retentive fibers can be increased, and the above-described fluffing of the water-retentive fibers can be made less likely to occur.

In still another aspect (aspect 5) of the present invention, in the absorbent article according to any one of aspects 1 to 4, at least the water-retentive fibers contained in the first fiber layer have an average fiber length of 5mm or more and less than 35 mm.

In the absorbent article of this aspect, since the average fiber length of the water-retentive fibers contained in the first fiber layer is within the above-specified range, the above-described fluffing of the water-retentive fibers is less likely to occur, and the softness and feel of the water-retentive fibers are more likely to be maintained, and as a result, the skin-contactability of the topsheet can be further improved.

In still another aspect (aspect 6) of the present invention, in the absorbent article according to any one of aspects 1 to 5, the thermoplastic resin fibers are conjugate fibers, and a resin component having a low melting point in the conjugate fibers is exposed on the surface of the conjugate fibers.

In the absorbent article of the present aspect, since the thermoplastic resin fibers are conjugate fibers, the resin component having a low melting point exposed on the fiber surface (for example, the resin component constituting the sheath portion in the case of the core-sheath conjugate fiber, and the resin component on one side in the case of the parallel conjugate fiber) melts and covers the water-retentive fiber, whereas the resin component having a high melting point (for example, the resin component constituting the core portion in the case of the core-sheath conjugate fiber, and the resin component on the other side in the case of the parallel conjugate fiber) can maintain a state of being entangled with the water-retentive fiber and the other conjugate fiber, and can maintain a predetermined volume as the surface sheet.

Thus, the absorbent article of this aspect is less likely to generate the above-described fluffing of the water-retentive fibers, and the top sheet is likely to ensure good flexibility, feel, cushioning properties, and the like.

In still another aspect (aspect 7) of the present invention, in the absorbent article according to any one of aspects 1 to 6, the top sheet has a compressed portion that is recessed in a thickness direction from a skin-side surface.

In the absorbent article of this aspect, since the top sheet has the compressed portions formed by embossing or the like, the compressed portions can hold the water-retentive fibers, and the above-described fluffing of the water-retentive fibers can be made less likely to occur.

In still another aspect (aspect 8) of the present invention, in the absorbent article according to any one of aspects 1 to 7, the top sheet includes: a plurality of protrusions extending along the longitudinal direction of the absorbent article and arranged at intervals in the width direction of the absorbent article; and a plurality of concave portions extending in a longitudinal direction of the absorbent article and located between the convex portions adjacent to each other.

In the absorbent article of this aspect, since the surface sheet has the specific uneven structure, the contact area between the skin-side surface of the surface sheet and the skin of the wearer is reduced, and therefore, the possibility of causing uncomfortable irritation to the skin of the wearer due to fluffing of the thermoplastic resin fibers and the water-retentive fibers contained in the surface sheet can be further reduced.

In still another aspect (aspect 9) of the present invention, in the absorbent article according to aspect 8, the absorbent article further includes an auxiliary sheet located on a non-skin side of the top sheet, and the top sheet is joined to the auxiliary sheet at the plurality of concave portions, respectively.

In the absorbent article of this aspect, since the top sheet is joined to the auxiliary sheet at each of the plurality of concave portions, the water-retentive fibers can be retained at the joint portions of the top sheet and the auxiliary sheet, and the above-described fluffing of the water-retentive fibers can be made less likely to occur.

In still another aspect (aspect 10) of the present invention, in the absorbent article according to any one of aspects 1 to 9, the water-retentive fibers are organic cotton.

In the absorbent article of this aspect, since the water-retentive fibers are organic cotton having excellent softness, hand feeling, and the like, the top sheet can easily secure excellent softness, hand feeling, and the like, and can realize more excellent skin contactability.

Further, if the surface sheet contains such organic cotton, the following advantages are also provided: the wearer of the absorptive article can feel the feeling of reassurance caused by the use of natural materials for the surface sheet.

In still another aspect (aspect 11) of the present invention, in the absorbent article according to any one of aspects 1 to 10, the fiber density of the second fiber layer is higher than the fiber density of the first fiber layer.

In the absorbent article of the present aspect, since the fibers constituting the second fiber layer are configured to have a fiber density higher than that of the first fiber layer, the fibers constituting the second fiber layer can be brought close to each other, and the capillary phenomenon can be more strongly generated in the second fiber layer, so that the liquid excrement excreted onto the skin-side surface of the topsheet (i.e., the skin-side surface of the first fiber layer) can be rapidly introduced into the second fiber layer, and further, the liquid excrement introduced into the second fiber layer can be rapidly transferred to the non-skin side of the second fiber layer by the thermoplastic resin fibers.

In this way, the absorbent article of this aspect can ensure good absorption performance while having a top sheet excellent in skin-contactability.

In still another aspect (aspect 12) of the present invention, in the absorbent article according to any one of aspects 1 to 11, an average distance between the fibers of the second fiber layer is shorter than an average distance between the fibers of the first fiber layer.

In the absorbent article of the present aspect, the average distance between the fibers of the second fiber layer is shorter than the average distance between the fibers of the first fiber layer, so that the fibers of the second fiber layer can be brought close to each other, and the capillary phenomenon can be more strongly generated in the second fiber layer, whereby the liquid excrement excreted onto the skin-side surface of the first fiber layer can be quickly introduced into the second fiber layer, and further, the liquid excrement introduced into the second fiber layer can be quickly transferred to the non-skin side of the second fiber layer by the thermoplastic resin fibers.

In still another aspect (aspect 13) of the present invention, in the absorbent article according to any one of aspects 1 to 12, the absorbent article further includes a pair of side sheets positioned on a skin side of the top sheet at both ends in the width direction, and a coefficient of kinetic friction of the pair of side sheets when wet is lower than a coefficient of kinetic friction of the top sheet when wet.

In the absorbent article of this aspect, the pair of side sheets which are likely to come into contact with the skin around the legs of the wearer have a lower coefficient of dynamic friction than the top sheet having excellent skin contact properties, and therefore, the absorbent article can provide smoother skin contact properties.

Effects of the invention

According to the present invention, an absorbent article including a topsheet that is less likely to cause uncomfortable irritation to the skin of a wearer and that has excellent skin-contactability can be provided.

Drawings

Fig. 1 is a plan view of a sanitary napkin 1 according to an embodiment of the present invention, as viewed from a topsheet 2 side in a thickness direction T in a developed state.

Fig. 2 is a sectional view of the sanitary napkin 1 of fig. 1 taken along line II-II.

Fig. 3 is an enlarged schematic view of a main portion of the first fiber layer 2a in the surface sheet 2.

Fig. 4 (a) is an enlarged plan view of the surface sheet 2, and fig. 4 (b) is a cross-sectional view of the surface sheet 2 of fig. 4 (a) taken along the line IVb-IVb.

Fig. 5 is an electron micrograph of the first fiber layer in the surface sheet of example 1 of the present invention.

Fig. 6 is a photograph showing the occurrence of fuzz in example 1 of the present invention and comparative examples 1 and 2.

Detailed Description

Hereinafter, preferred embodiments of the absorbent article of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, unless otherwise specified, "when viewed from above in the vertical direction along the thickness direction of an object (for example, a sanitary napkin (absorbent article) or the like) placed on a horizontal surface in an unfolded state" is simply referred to as "in plan view".

Fig. 1 is a plan view of a sanitary napkin 1 for menstrual period according to an embodiment of the present invention, as viewed from a topsheet 2 side in a thickness direction T in a developed state, and fig. 2 is a cross-sectional view of the sanitary napkin 1 for menstrual period in fig. 1, taken along line II-II.

As shown in fig. 1 and 2, the sanitary napkin 1 of the present embodiment has a longitudinal direction L, a width direction W, and a thickness direction T orthogonal to each other, and has a longitudinal center line C extending along the longitudinal direction L through the center of the width direction W_L(imaginary line) and a width-direction center line C passing through the center of the length direction L and extending in the width direction W_W(phantom line).

In the present specification, the sanitary napkin 1 is to be disposed with respect to the center line C in the width direction in the longitudinal direction L thereof_WThe relatively close side is referred to as the inner side of the longitudinal direction L and is opposite to the center line C in the width direction_WThe relatively far side is referred to as the outer side in the longitudinal direction L. Also in physiologyThe sanitary napkin 1 is to be disposed in the width direction W with respect to the longitudinal center line C_LThe side relatively close to the center line is referred to as the inner side in the width direction W, and is referred to as the longitudinal center line C_LThe relatively distant side is referred to as the outer side in the width direction W.

In the present specification, an arbitrary direction in a plane including the longitudinal direction L and the width direction W is referred to as a "plane direction".

In the present specification, the side of the sanitary napkin 1 closer to the skin surface of the wearer when worn is referred to as the skin side, and the side of the sanitary napkin 1 farther from the skin surface of the wearer when worn is referred to as the non-skin side, in the thickness direction T of the sanitary napkin 1.

The definitions of the above terms are also used in the same manner for various members constituting the sanitary napkin 1 and for absorbent articles other than the sanitary napkin 1.

[ sanitary napkin for physiological period ]

As shown in fig. 1, a sanitary napkin 1 (an example of an "absorbent article" in the present invention) according to an embodiment of the present invention is formed in a substantially rectangular shape that is long in the longitudinal direction L and short in the width direction W in a plan view, and has a vertically long shape in which both end edges in the longitudinal direction L protrude outward in the longitudinal direction L so as to draw a circular arc.

Further, the sanitary napkin 1 has a pair of

flaps

9, 9 at the central portion in the longitudinal direction L, and the pair of

flaps

9, 9 protrude such that both end portions in the width direction W of the sanitary napkin 1 are formed into a substantially trapezoidal shape toward the outside in the width direction W.

The shape of the sanitary napkin 1 in plan view is not limited to this shape, and any shape (for example, a rectangle, an ellipse, an hourglass shape, etc.) corresponding to various usage forms may be employed as long as the shape is elongated such that the length in the longitudinal direction L is longer than the length in the width direction W. The shape of the wing portion 9 is not limited to the above-described substantially trapezoidal shape, and may be, for example, a semicircular shape, a semielliptical shape, or the like.

As shown in fig. 2, the sanitary napkin 1 of the present embodiment has, as basic configurations, a front sheet 2 forming the skin-side surface of the sanitary napkin 1, a back sheet 3 forming the non-skin-side surface of the sanitary napkin 1, and an absorbent body 4 disposed between these two sheets, in the thickness direction T.

In the present embodiment, as shown in fig. 1 and 2, the sanitary napkin 1 further includes an auxiliary sheet 5 disposed between the topsheet 2 and the absorbent body 4 in the thickness direction T, and a pair of

side sheets

6, 6 disposed at both ends in the width direction W of the sanitary napkin 1.

In the present embodiment, the pair of

side sheets

6 and 6 are provided such that the skin-side surface of the inner end portion in the width direction W of each side sheet 6 is joined in an overlapping manner to the non-skin-side surfaces of the pair of

annular portions

5L and 5L formed by folding back the both end portions in the width direction W of the auxiliary sheet 5 toward the non-skin side, and the non-skin-side surface of the outer end portion in the width direction W of each side sheet 6 is joined to the skin-side surface of the back sheet 3.

Hereinafter, various members constituting the sanitary napkin 1 according to the present embodiment will be described in more detail.

Here, fig. 3 is a schematic view in which a main part of the first fiber layer 2a in the surface sheet 2 is enlarged, fig. 4 (a) is an enlarged plan view of the surface sheet 2, and fig. 4 (b) is a cross-sectional view of the surface sheet 2 of fig. 4 (a) taken along the line IVb-IVb.

[ surface sheet ]

As shown in fig. 1, the topsheet 2 has a vertically long planar shape of a substantially rectangular shape extending in the longitudinal direction L from the longitudinal end on the front side to the longitudinal end on the rear side of the sanitary napkin 1 in the planar view. As shown in fig. 2, the top sheet 2 is a liquid-permeable sheet-like member disposed at a position on the skin side in the thickness direction T of the sanitary napkin 1 and forming a contact surface (i.e., the skin-side surface of the sanitary napkin 1) that can come into contact with the skin of the wearer.

In this specification, the following areIn the longitudinal direction L of the sanitary napkin 1, the side of the sanitary napkin 1 which is closer to the abdomen of the wearer when worn is referred to as the front side, and the other side which is farther from the abdomen of the wearer is referred to as the rear side. In this connection, the sanitary napkin 1 has a front region AF and a central region a in the longitudinal direction L as shown in fig. 1_CAnd a rear side area A_B。

In the present embodiment, the top sheet 2 is a sheet-like member having a two-layer structure including a first fiber layer 2a and a second fiber layer 2b, and the first fiber layer 2a contains water-retentive fibers F₁And the second fiber layer 2b is formed on the skin side surface of the front sheet 2 and contains thermoplastic resin fibers F₂And water-retentive fiber F₁And the surface of the top sheet 2 on the non-skin side is formed adjacent to the non-skin side of the first fibrous layer 2 a.

The top sheet 2 may further include one or more fiber layers on the non-skin side of the second fiber layer 2b, or may have a multilayer structure of three or more layers as a whole.

(first fiber layer)

As described above, the first fiber layer 2a contains the water-retentive fibers F₁。

Water-retentive fiber F₁The fiber is not particularly limited as long as it has a property of absorbing and retaining water (water-retaining property), and examples thereof include cellulose fibers.

The cellulose-based fiber is not particularly limited as long as it is a fiber containing cellulose, and examples thereof include natural cellulose fibers, regenerated cellulose fibers, purified cellulose fibers, and semi-synthetic cellulose fibers. Examples of the natural cellulose fibers include plant fibers, seed fibers such as cotton, bast fibers such as hemp, vein fibers such as manila hemp, and fruit fibers such as coconut.

Examples of cotton (fiber) include cotton (i.e., upland cotton (ヒルスツム sponge コットン) such as cotton of upland cotton (upland cotton), sea island cotton, asian cotton, and african cotton. As Cotton (fiber), Organic Cotton, quasi-Organic Cotton (Pre Organic Cotton, trademark), or the like may be used. The Organic cotton means cotton certified by GOTS (Global Organic Textile Standard).

Examples of the regenerated cellulose fibers include rayon, for example, viscose rayon obtained from viscose, and Cupro rayon (also referred to as "Cupro") obtained from a Cupro solution of cellulose, Polynosic, modal, or the like.

Examples of the purified cellulose fibers include lyocell fibers, and specifically, a method of forming fibers by dissolving a slurry in an aqueous solution of N-methylmorpholine-N-oxide to form a spinning dope (slurry) and extruding the spinning dope into a dilute solution of N-methylmorpholine-N-oxide. Purified cellulose is sold on the market as Tencel (Tencel, trademark), for example.

Examples of the semi-synthetic cellulose fibers include acetate fibers such as triacetyl cellulose and diacetyl cellulose.

Among the above-mentioned various water-retentive fibers, the water-retentive fiber F is preferred from the viewpoint of water retentivity and skin contact property₁Preferably natural cellulose fibers, more preferably cotton, and even more preferably organic cotton.

If the Water-retentive fiber F₁If the organic cotton is excellent in flexibility, texture, and the like, the surface sheet 2 can easily secure excellent flexibility, texture, and the like, and can realize more excellent skin contactability. Further, if the top sheet 2 contains such organic cotton, the following advantages are also provided: the wearer of the sanitary napkin 1 during the menstrual period is provided with a feeling of reassurance due to the use of natural materials for the topsheet 2.

(second fiber layer)

As described above, the second fiber layer 2b contains the thermoplastic resin fibers F₂And water-retentive fiber F₁。

As long as the thermoplastic resin fiber F₂The fibers are not particularly limited as long as they are fibers made of a thermoplastic resin (generally, hydrophobic fibers). As forming thermoplastic resin fiber F₂Examples of the thermoplastic resin of (2) include Polyethylene (PE), polypropylene (PP) and ethyleneKnown resins such as olefin-based resins such as ethylene-vinyl acetate copolymers (EVA), polyester-based resins such as polyethylene terephthalate (PET) and polylactic acid (PLA), and polyamide-based resins such as 6-nylon may be used alone or in combination of two or more.

Further, thermoplastic resin fiber F₂The structure of (b) is not particularly limited, and examples thereof include: core-sheath type composite fibers such as PET (core)/PE (sheath), PP (core)/PE (sheath), side-by-side type composite fibers, sea-island type composite fibers, and the like; hollow-type fibers; flat, Y-shaped, C-shaped and other special-shaped section fibers; a latent or dominant crimp of a three-dimensionally crimped fiber; the fibers having the above-described structure may be used alone or two or more kinds of fibers may be used in combination, for example, as divided fibers divided by physical load such as water flow, heat, embossing, or the like.

In the sanitary napkin 1 of the present embodiment, the thermoplastic resin fibers F of the second fiber layer 2b₂Is a core-sheath type composite fiber of PP (core)/PE (sheath).

The water-retentive fibers F contained in the second fiber layer 2b₁The same as the water-retentive fibers F1 of the first fibrous layer 2 a.

In the first fiber layer 2a and the second fiber layer 2b constituting the top sheet 2, the water-retentive fibers F among the fibers constituting the first fiber layer 2a₁The ratio of (A) to (B) of the water-retentive fibers F in the fibers constituting the second fiber layer 2b₁The ratio of (a) to (b) is high. Thereby, even if the surface sheet 2 contains the thermoplastic resin fiber F₂Thermoplastic resin fiber F₂The skin of the wearer is less likely to be touched, and uncomfortable stimulation such as a stiff touch or a needle-pricked touch is less likely to be given to the wearer.

In addition, from the viewpoint of improving the skin-contactability of the top sheet 2, the water-retentive fibers F among the fibers constituting the first fiber layer 2a₁The ratio of (a) to (b) is preferably based on the total constituent fibers of the first fiber layer 2a (excluding thermoplastic resin fibers F described later)₂Other than the melt) is 70 to 100% by mass, more preferably 80 to 100% by massThe amount% is more preferably 90 to 100% by mass. By mixing water-retaining fiber F₁The proportion of (b) is 70% by mass or more, whereby the wearer can easily recognize that the skin-side surface of the topsheet 2 formed of the first fiber layer 2a contains the water-retentive fibers F₁The user can easily feel the contact comfort in practice.

Among the fibers constituting the first fiber layer 2a, the water-retentive fibers F₁The other fibers are not particularly limited as long as they can form a liquid-permeable layer, and may contain, for example, thermoplastic resin fibers F contained in the second fiber layer 2b₂The same thermoplastic resin fibers.

In the present embodiment, the first fiber layer 2a is configured of water-retentive fibers F₁The water-retentive fiber F is not contained at a ratio of 100 mass%₁Other than fibers.

In the present embodiment, the water-retentive fibers F of the second fiber layer 2b₁Has an average fiber length smaller than that of the water-retentive fibers F of the first fiber layer 2a₁Has a short average fiber length. This makes it easy for at least the fibers constituting the second fiber layer 2b to approach each other (i.e., the distance between fibers is easily shortened), and the capillary phenomenon is more likely to occur, so that liquid excrement such as menstrual blood and urine can be more strongly sucked into the second fiber layer 2 b.

As shown in FIG. 3, at least a part of the water-retentive fibers F contained in the first fiber layer 2a₁At the interweaving part P of the fibres_EAt least a part of the interleaved part P_EIs formed of thermoplastic resin fibers F₂Melt F of_2MAnd (6) covering.

In this way, in the sanitary napkin 1 for menstrual period of the present embodiment, the water-retentive fibers F of the first fiber layer 2a in the topsheet 2₁Is in a ratio to the water-retentive fibers F of the second fibrous layer 2b₁In the second fiber layer 2b, the thermoplastic resin fibers F contained in the second fiber layer 2b are high in the ratio₂Becomes an interlaced part P of the fibers contained in the first fiber layer 2a_EAt least a part of the interleaved part P_ECovering with water-retaining fiber F₁Melt F of_2MTherefore, even if the surface sheet 2 contains the thermoplastic resin fiber F₂Thermoplastic resin fiber F₂And is less likely to come into contact with the skin of the wearer, and thus uncomfortable stimulation such as a stiff touch or a needle-pricked touch is less likely to be given to the wearer.

Further, the sanitary napkin 1 of the present embodiment is configured such that at least a part of the water-retentive fibers F contained in the first fiber layer 2a₁At the interweaving part P of the fibres_EAt least a part of the interleaved part P_EIs formed of thermoplastic resin fibers F₂Melt F of_2MBy this covering, the fibers in the top sheet 2 are not easily entangled with each other, and the water-retentive fibers F are hardly loosened₁Is not easily broken, so that the fibers F are not easily loosened and water-retaining due to entanglement₁Water-retentive fiber F by breaking₁The wearer can be less likely to be subjected to uncomfortable irritation due to the fuzz.

Therefore, the sanitary napkin 1 of the present embodiment is a sanitary napkin for menstrual period including the topsheet 2 which is less likely to cause uncomfortable irritation to the skin of the wearer and has excellent skin-contactability.

In the present specification, the interlaced part refers to a part where fibers are interlaced with each other, and is a part including an interlaced point and the periphery of the interlaced point.

In the present specification, the molten material means a material in a state of being solidified through a molten state.

As described above, in the present embodiment, the thermoplastic resin fibers F contained in the second fiber layer 2b as the top sheet 2₂The core-sheath type composite fiber is used. Thus, in the surface sheet 2, the sheath portion of the core-sheath composite fiber made of the resin component having a low melting point is melted to cover the water-retentive fiber F₁On the other hand, the core portion made of a resin having a high melting point can maintain the water-retentive fiber F₁And other core-sheath type composite fibers (thermoplastic resin fibers F)₂) The interlaced state can maintain a predetermined volume as a surface sheet.

In the case of using a conjugate fiber in which a resin component having a low melting point, such as a side-by-side conjugate fiber, is exposed on the surface of the conjugate fiber, as the thermoplastic resin fiber, the same effects as described above can be obtained.

Further, in the present embodiment, the thermoplastic resin fibers F described above₂In other words, one thermoplastic resin fiber F₂With a plurality of water-retaining fibers F₁Interweaving, and the one thermoplastic resin fiber F₂And a plurality of the water-retaining fibers F₁Is interleaved part P_ERespectively formed by the one thermoplastic resin fiber F₂Melt F of_2MAnd (6) covering.

Thus, if one thermoplastic resin fiber F₂With a plurality of water-retaining fibers F₁Is interleaved part P_EEach made of a thermoplastic resin fiber F₂Melt F of_2MCovering with a plurality of water-retentive fibers F₁Will pass through a thermoplastic resin fiber F₂The fibers are connected to each other, so that the above-mentioned fibers F having a water-retaining property and being loosened by entanglement can be more hardly generated₁And (3) fuzz caused by the breakage of the yarn.

In the present invention, it is preferable that the molten thermoplastic resin fiber is not exposed on the skin-side surface of the first fiber layer. If the melt of the thermoplastic resin fibers is not exposed on the skin-side surface of the first fiber layer, the wearer is less likely to feel the presence of the melt, and good skin-contactability of the topsheet can be more reliably obtained.

Water-retentive fibers F of the first fiber layer 2a₁The fiber length (average fiber length) of (a) is not particularly limited as long as the effect of the present invention is not impaired, but it is preferable that the water-retentive fibers F contained in at least the first fiber layer 2a₁Average fiber length of (2) to the thermoplastic resin fiber F₂Has a short average fiber length. If the water-retentive fibers F contained in the first fiber layer 2a₁Has an average fiber length larger than that of the thermoplastic resin fibers F contained in the second fiber layer 2b₂Has a short average fiber length, and is in contact with one thermoplastic resin fiber F contained in the second fiber layer 2b₂Water-retentive fibers F of the first fibrous layer 2a joined to each other₁The amount of the thermoplastic resin fibers F is increased, thereby increasing the amount of the thermoplastic resin fibers F per one of the water-retentive fibers₂Melt F of_2MThe amount of the water-retentive fibers F is less likely to be generated₁The fuzzing of (1).

The water-retentive fibers F contained in the first fiber layer 2a₁Specific examples of the average fiber length of (b) include average fiber lengths of 5mm to 80mm (i.e., 5mm to 80 mm). If the Water-retentive fiber F₁The average fiber length of (2) is 5mm or more, the water-retentive fiber F is easily maintained₁In addition to the softness and hand feeling of (2), since fibers are easily entangled with each other, sufficient strength is easily obtained. On the other hand, if the water-retentive fiber F₁When the average fiber length of (2) is 80mm or less, a part of the water-retentive fibers F₁Since the water-retentive fibers F hardly extend to the outside in the width direction W of the sanitary napkin 1 for menstrual period, liquid excrement can be hardly generated along the water-retentive fibers F extending to the outside in the width direction W₁And leaks in the width direction W of the sanitary napkin 1.

Further, the water-retentive fibers F contained in the first fiber layer 2a₁The average fiber length of (2) is preferably 5mm or more and 60mm or less, more preferably 5mm or more and less than 35 mm. If the water-retentive fibers F contained in the first fiber layer 2a₁The average fiber length of (2) is 5mm or more and less than 35mm, the above-mentioned water-retentive fiber F is hardly generated₁And the water-retentive fiber F is easily maintained₁The surface sheet 2 can be made more excellent in skin-contactability as a result of its softness and hand feeling.

The water-retentive fibers F in the first fiber layer 2a₁The fineness, average fiber length, and the like of the other fibers are not particularly limited, but the water-retentive fiber F is considered₁The water-retentive fibers F are preferred because of their effects on skin contact₁The same degree (in the range of 0.5 to 2 times). In the present embodiment, as described above, the first fiber layer 2a does not contain the water-retentive fibers F₁Of fibres other than。

Water-retentive fibers F of the fibers constituting the second fiber layer 2b₁The ratio of (A) is such that the water-retentive fibers F are larger than those of the first fiber layer 2a₁The ratio of (A) to (B) is not particularly limited. Water-retentive fibers F as the second fiber layer 2b₁The ratio of (b) is, for example, 50 to 90% by mass based on the total mass of all the constituent fibers of the second fiber layer 2 b. If the Water-retentive fiber F₁When the ratio of (b) is 50% by mass or more, the contact comfort can be improved in a state where pressure is applied in the thickness direction T, and when the water-retentive fiber F is used₁When the ratio of (B) is 90% by mass or less, the prevention of the coagulation of the thermoplastic resin fibers F can be more stably exerted₂Melt F of_2MAnd the effect of raising fuzz.

Further, the water-retentive fibers F of the second fiber layer 2b₁The proportion of (b) is preferably 60 to 85 mass%, more preferably 70 to 80 mass%. Correspondingly, the thermoplastic resin fibers F in the second fiber layer 2b₂The ratio of (b) is, for example, 10 to 50% by mass, preferably 15 to 40% by mass, and more preferably 20 to 30% by mass based on the total mass of all the constituent fibers of the second fiber layer 2 b.

The second fiber layer 2b is formed of water-retentive fibers F₁And thermoplastic resin fiber F₂In addition, a third fiber may be contained.

The water-retentive fibers F contained in the second fiber layer 2b₁Is preferably as fine as the water-retentive fibers F contained in the first fiber layer 2a₁The same is true.

Water-retentive fibers F of the second fiber layer 2b₁The fiber length (average fiber length) of (a) is not particularly limited as long as the effect of the present invention is not impaired, but is preferably the same as the first fiber layer 2a described above as compared with the thermoplastic resin fiber F₂Has a short average fiber length. If the Water-retentive fiber F₁Average fiber length of (2) to the thermoplastic resin fiber F₂Has a short average fiber length, is combined with one thermoplastic resin fiber F₂Water-retentive fibers F bonded to each other₁The amount of the thermoplastic resin fibers F is increased, and therefore, the thermoplastic resin fibers F per one of the water-retentive fibers can be increased₂Melt F of_2MThe amount of the fibers F adhering makes it less likely that the fibers are entangled with each other and the fibers F are loosened and held in water₁Is broken.

The water-retentive fibers F contained in the second fiber layer 2b₁Specific examples of the average fiber length of (3) include average fiber lengths of 3mm to 40 mm. If the Water-retentive fiber F₁The average fiber length of (3) or more, the water-retentive fiber F is easily maintained₁In addition to the softness and hand feeling of (2), since fibers are easily entangled with each other, sufficient strength is easily obtained. On the other hand, if the water-retentive fiber F₁When the average fiber length of (2) is 40mm or less, the degree of dynamic freedom of the fibers in a web state is improved in the production of the second fiber layer 2b, and the water-retentive fibers F₁Easily accessible thermoplastic resin fiber F₂The distance between the fibers in the second fiber layer 2b is likely to be short, and the fiber density of the second fiber layer 2b is likely to be high.

Further, the water-retentive fibers F contained in the second fiber layer 2b₁The average fiber length of (2) and the water-retentive fibers F of the first fiber layer 2a₁Also, there is no particular limitation, but it is preferably 5mm or more and less than 35 mm. If the water-retentive fibers F contained in the second fiber layer 2b₁When the average fiber length of (A) is in such a range, the water-retentive fiber F is easily maintained₁The surface sheet 2 can be made more excellent in skin-contactability as a result of its softness and hand feeling.

In the present invention, the water-retentive fibers F contained in at least the second fiber layer 2b₁A mixed water-retentive fiber obtained by mixing two or more types of water-retentive fibers having different average fiber lengths may be used. For example, the water-retentive fibers may be formed by mixing water-retentive fibers having an average fiber length of 15 to 40mm (preferably 20 to 35mm) as water-retentive fibers having a long average fiber length and water-retentive fibers having a short average fiber length and having an average fiber length of 3 to 25mm (preferably 5 to 20 m)m) water-retentive fibers are mixed and used. When such a mixed water-retentive fiber is used as the water-retentive fiber F of the second fiber layer 2b₁When used, the water retentivity and skin contact property of the second fiber layer 2b can be improved by the water retentivity fibers having a long average fiber length, and the inter-fiber distance of the second fiber layer 2b can be shortened by the water retentivity fibers having a short average fiber length.

In the case where the second fibrous layer 2b includes one or more fibrous layers on the non-skin side, that is, in the case where the top sheet 2 has a multilayer structure of three or more layers as a whole, from the viewpoint of further improving the liquid permeability, it is preferable that the water-retentive fibers F are provided closer to the fibrous layer on the non-skin side surface of the top sheet 2 than to the fibrous layer on the non-skin side surface₁The lower the proportion of (A) is and the water-retaining fiber F₁The shorter the average fiber length.

Thermoplastic resin fibers F from the second fiber layer 2b₂Water-retentive fibers F as main constituent fibers of the first fiber layer 2a₁The thermoplastic resin fibers F of the second fiber layer 2b are preferable from the viewpoint of ease of entanglement of the fibers, that is, ease of transfer of liquid excreta from the first fiber layer 2a and prevention of interlayer peeling between the first fiber layer 2a and the second fiber layer 2b₂Is finer than the water-retentive fibers F of the first fiber layer 2a₁The fineness of (2) is small.

In addition, the thermoplastic resin fibers F of the second fiber layer 2b₂The fiber length (average fiber length) of (a) is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include 10mm to 80 mm. However, the thermoplastic resin fibers F from the second fiber layer 2b₂Water-retentive fibers F as main constituent fibers of the first fiber layer 2a₁The thermoplastic resin fibers F of the second fiber layer 2b are preferable from the viewpoint of ease of entanglement of the fibers, that is, ease of transfer of liquid excreta from the first fiber layer 2a and prevention of interlayer peeling between the first fiber layer 2a and the second fiber layer 2b₂The average fiber length of (2) is larger than the water-retentive fibers F of the first fiber layer 2a and the second fiber layer 2b₁The average fiber length of (2) is long, and for example, an average fiber length of 15mm to 100mm is mentionedLength.

The thickness of each of the first fiber layer 2a and the second fiber layer 2b is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include a thickness of 0.05mm to 4mm, preferably a thickness of 0.1mm to 3mm, and more preferably a thickness of 0.2mm to 2 mm.

However, when the thickness of the first fiber layer 2a is relatively large and the thickness of the second fiber layer 2b is relatively small, the skin contact property of the first fiber layer 2a is easily improved and the rewet to the skin of the wearer is easily suppressed, and when the thickness of the first fiber layer 2a is relatively small and the thickness of the second fiber layer 2b is relatively large, the water-retentive fibers F of the first fiber layer 2a are easily retained₁Easily formed from the thermoplastic resin fibers F of the second fiber layer 2b₂Melt F of_2MTherefore, the water-retentive fibers F can be more reliably inhibited₁And the fuzz is caused.

The thickness of the top sheet 2 (i.e., the total thickness of the fiber layers) is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include a thickness of 0.1 to 5mm, preferably a thickness of 0.4 to 4mm, and more preferably a thickness of 0.8 to 3 mm.

Here, the ratio of the types of fibers in a sheet such as a fiber layer can be measured as follows.

That is, the water-retentive fibers and the thermoplastic resin fibers are colored with different colors in the following order, whereby the ratio of the types of fibers can be measured.

(1) The surface sheet 2 was cut into a size of 70mm × 70mm to obtain a sample.

(2) The water-retentive fibers were colored blue only and the thermoplastic resin fibers were colored yellow only by coloring with a reagent KayastainQ (color dyeing, ltd.).

(3) The ratio of the blue color to the yellow color when observed from the skin-side surface (first fiber layer 2a) of the sample was measured in a range of 50mm × 50mm using a digital microscope VHX-100 manufactured by keyence corporation, whereby the ratio of the types of fibers in the first fiber layer 2a was obtained. On the other hand, the ratio of blue to yellow when viewed from the non-skin side surface (second fiber layer 2b) was measured in a range of 50mm × 50mm, and the ratio of the types of fibers in the second fiber layer 2b was obtained.

In the case where the magnitude relation of the ratio of blue to yellow is clear in terms of appearance when the magnitude relation of the ratio of blue to yellow is determined for the type of fiber, the determination may be made by appearance, but the magnitude relation of the ratio of blue to yellow may not be determined by appearance alone, and the determination may be made as follows: the number of fibers colored in different colors is counted, the total mass of each fiber is calculated from the number and structural characteristics of each fiber (for example, the size, specific gravity, etc. of the fiber such as the fiber length and fineness), and the total mass is compared to determine the total mass.

The distance between the constituent fibers in a sheet such as a fiber layer can be measured by the following measurement method.

(1) The surface sheet 2 was cut into a size of 10mm × 10mm to obtain a sample.

(2) Images of the skin-side surface (first fiber layer 2a) and the non-skin-side surface (second fiber layer 2b) of the surface sheet 2 were taken with a digital microscope VHX-100 (lens VH-Z20R + variable illumination accessory VH-K20) manufactured by kynshi, ltd., under conditions of a photographing magnification of 200 times and a measurement area of 1300 μm in vertical direction × 1735 μm in horizontal direction. At this time, images were taken once per 20 μm depth in the range of 0 μm to 100 μm for each of the skin-side surface and the non-skin-side surface, and a total of five images were taken.

(3) The area of the portion where no fiber is present is determined from each of the obtained images. At this time, the presence or absence of a fiber in each pixel is determined based on whether the brightness of each pixel in each obtained image is lower or higher than a predetermined brightness (threshold value), and the presence or absence of a fiber in the captured region in each image is determined. However, since light is transmitted only through a portion where no fiber is present and brightens (that is, since the brightness is high), the area of the portion where no fiber is present in the imaging region is determined by this point.

(4) The porosity was calculated by subtracting the area of the obtained fiber-free region from the area of the imaging region (measurement area) and dividing the subtracted area by the area of the imaging region (measurement area). Such calculation was performed for images captured at 20 μm per depth to calculate five void ratios.

(5) The average of the five calculated void ratios is set as the void ratio of each of the skin-side surface (first fibrous layer 2a) and the non-skin-side surface (second fibrous layer 2b) of the top sheet 2. By comparing the magnitudes of the void ratios, the magnitude of the inter-fiber distance can be determined. That is, when the porosity is large, the distance between fibers is large. For example, the surface sheet 2 has a void ratio of 25.4% on the skin side (the first fiber layer 2 a: a surface of, for example, cotton fibers (water-retentive fibers) of 100%) and a void ratio of 24.5% on the non-skin side (the second fiber layer 2 b: a surface of, for example, cotton fibers (water-retentive fibers) of 60% and thermoplastic resin fibers of 40%).

The fiber length (average fiber length) of the fibers of a sheet such as a fiber layer may be measured in accordance with JIS L1015: the measurement was performed by the "A7.1.1A method (standard method) in" a7.1 measurement of fiber length "in appendix a of 2010, and the method of measuring the length of each fiber on a graduated glass plate". The above method is a test method corresponding to ISO 6989 published in 1981.

The square meter weight of a sheet such as a fiber layer can be measured by the following measurement method. That is, a single fiber layer was prepared, the fiber layer was cut into 5cm × 5cm to obtain a sample, the sample was dried at 100 ℃ or higher in an atmosphere, and the mass of the sample was measured. Next, the measured mass was divided by the area of the sample to calculate the square meter weight of the sample. The square meter weight of the sheet was defined as the value obtained by averaging the square meter weights of the ten samples.

The thickness of a sheet such as a fiber layer can be measured by the following measurement method. That is, the cross-section of the surface sheet 2 was photographed from the vertical direction with an enlarged image using a digital microscope VHX-100 manufactured by kynshi, ltd. In this case, the magnified image is an image magnified at a magnification such that the entire surface sheet 2 in the thickness direction T can be captured, and the magnification is, for example, 20 times to 50 times. The obtained enlarged image (three-dimensional image) is converted into a two-dimensional image, and the thickness of each fiber layer is measured in the two-dimensional image. The average of the thicknesses measured at the three different cutting planes was defined as the thickness of the surface sheet 2.

In the sanitary napkin 1 of the above-described embodiment, the average distance between the constituent fibers of the second fiber layer 2b is preferably shorter than the average distance between the constituent fibers of the first fiber layer 2 a. When the average distance between the constituent fibers of the second fiber layer 2b is shorter than the average distance between the constituent fibers of the first fiber layer 2a, the fibers of the second fiber layer 2b approach each other, and capillary phenomenon can be more strongly generated in the second fiber layer 2b, so that liquid excrement excreted onto the skin-side surface of the first fiber layer 2a can be quickly drawn into the second fiber layer 2b, and further, the thermoplastic resin fibers F can be utilized₂The liquid excreta introduced into the second fibrous layer 2b is rapidly transferred to the non-skin side of the second fibrous layer 2 b.

Therefore, the sanitary napkin 1 having the above-described structure can ensure excellent skin-contactability of the topsheet 2 and good absorption performance.

Further, in the sanitary napkin 1 of the present embodiment, the fiber density of the second fiber layer 2b is preferably higher than the fiber density of the first fiber layer 2 a. That is, it is preferable that the fiber density gradient is present in the thickness direction T of the top sheet 2 so that the fiber density increases from the first fiber layer 2a toward the second fiber layer 2 b.

As described above, when the fiber density of the second fiber layer 2b is higher than the fiber density of the first fiber layer 2a, the fibers constituting the second fiber layer 2b approach each other, and the capillary phenomenon can be more strongly generated in the second fiber layer 2b, so that the liquid excrement supplied onto the skin-side surface of the topsheet 2 (that is, the skin-side surface of the first fiber layer 2a) can be rapidly taken into the second fiber layer 2b, and further, the thermoplastic resin fibers F can be utilized₂The liquid excrement introduced into the second fiber layer 2b is rapidly transferred to the non-skin side of the second fiber layer 2b。

However, when one or more fiber layers are further provided on the non-skin side surface of the second fiber layer 2b, that is, when the top sheet 2 has a multilayer structure of three or more layers, the fiber density is preferably relatively higher as the fiber layer on the non-skin side surface of the top sheet 2 is closer. This can further improve the liquid permeability from the fibrous layer on the skin side to the fibrous layer on the non-skin side, and can further stably transfer liquid excrement to the auxiliary sheet 5 and the absorbent body 4.

The fiber density of a sheet such as a fiber layer can be measured by the following measurement method.

(1) The surface sheet 2 was cut into a size of 10mm × 10mm to obtain a sample.

(2) The cross-section of the sample parallel to the thickness direction T was observed under magnification using a scanning electron microscope (JCM-5100, manufactured by Nippon electronics Co., Ltd.). The magnification is a magnification (for example, 150 to 500 times) that can be measured in one screen for a cross section of 30 to 60 fibers.

(3) The number of cross sections of the fibers in each fiber layer was measured by trisecting the observation area in the thickness direction T into a skin-side layer, an intermediate layer, and a non-skin-side layer, with the skin-side layer being the first fiber layer 2a and the non-skin-side layer being the second fiber layer 2 b. That is, the number of cross sections of the fiber cut by the predetermined area of the cutting plane is counted.

(4) The number of cross sections of the obtained fiber was converted to mm²The number of cross sections of the fiber (2) is defined as the fiber density (root/mm)²). The measurement was performed at three points, and the average of the measured values was taken as the fiber density of the sample. That is, as the fiber density, the density of the number of fibers is used. In other words, the number of fibers per unit area on a cross section parallel to the thickness direction T is used as the fiber density.

As the fiber density, the number of fibers per unit volume may be used. The number of fibers per unit volume can be solved by analysis based on X-ray CT, for example. The relative comparison of fiber density between fiber layers (e.g., comparison of size) is the same, although the numerical values of fiber density are different for fiber density per unit area and fiber density per unit volume.

In addition, as shown in fig. 3, in the present embodiment, a part of the thermoplastic resin fibers F contained in the second fiber layer 2b₂Are thermally welded to each other. That is, the thermoplastic resin fiber F can be regarded as a part₂Are joined to each other by heat fusion at the portions where the thermoplastic resin fibers are joined to each other, forming a thermoplastic resin fiber F in the second fiber layer 2b₂Of the matrix of (a).

The sanitary napkin 1 having such a structure can utilize a part of the thermoplastic resin fibers F thermally fused to each other in the second fiber layer 2b₂To stably maintain the shape of the second fiber layer 2b, even if the water-retentive fibers F contained in the second fiber layer 2b₁Is relatively short, and is capable of forming the water-retentive fiber F₁Stably held in the thermoplastic resin fiber F without being biased₂In (a matrix of) between. Thus, the sanitary napkin 1 of the present embodiment can stably transfer the liquid excrement introduced into the second fiber layer 2b to the absorbent body 4 (and the auxiliary sheet 5) without being biased, and can exhibit excellent absorption performance.

The thermoplastic resin fibers F of the sanitary napkin 1 for physiological use₂It is also possible not to thermally fuse each other in this way.

In addition, as shown in fig. 4, in the present embodiment, the thermoplastic resin fibers F of the second fiber layer 2b₂At least a part of which is exposed on the skin-side surface of the first fiber layer 2 a. That is, the thermoplastic resin fibers F in the second fiber layer 2b₂The thermoplastic resin fibers F of the second fiber layer 2b while stably maintaining the shape of the second fiber layer 2b₂Is continuously fed from the second fiber layer 2b into the interior of the first fiber layer 2aAnd further reaches the skin-side surface of the first fiber layer 2 a.

In the sanitary napkin 1 having such a structure, the thermoplastic resin fibers F of the second fiber layer 2b pass through₂The water-retentive fibers F of the first fiber layer 2a can be continuously extended into the first fiber layer 2a₁Stably held in the thermoplastic resin fiber F₂Therefore, even when the average distance between the constituent fibers of the first fiber layer 2a is relatively long and the strength of the first fiber layer 2a is relatively weak, the slack can be suppressed. In addition, the water-retentive fibers F of the first fiber layer 2a are formed₁Retained in the thermoplastic resin fiber F₂And further made of the thermoplastic resin fiber F₂Melt F of_2MBy covering, the water-retentive fibers F can be effectively inhibited₁And (3) fuzz caused by the breakage of the yarn.

Therefore, the sanitary napkin 1 having such a structure can further improve the skin-contactability of the first fibrous layer 2a of the topsheet 2.

Further, the thermoplastic resin fibers F having no water retentivity in the second fiber layer 2b are formed₂Is present in the first fiber layer 2a, it is possible to promote passage of liquid excrement from the first fiber layer 2a through the thermoplastic resin fibers F₂The transfer to the second fiber layer 2b enables the liquid excrement to be stably transferred to the absorbent body 4 (and the auxiliary sheet 5).

The thermoplastic resin fibers F of the second fiber layer 2b of the sanitary napkin 1 for physiological use₂The first fiber layer 2a may not be exposed on the skin-side surface.

In the present embodiment, among the fibers constituting the top sheet 2, the fibers present at both ends in the width direction W of the top sheet 2 are oriented along the longitudinal direction L of the top sheet 2 more than the fibers present at the center in the width direction W of the top sheet 2. That is, in the top sheet 2 of the present embodiment, the orientation of the fibers in the longitudinal direction L in the central portion in the width direction W is relatively small, and the orientation of the fibers in the longitudinal direction L in the both end portions in the width direction W is relatively large.

In the sanitary napkin 1 having such a structure, since the fiber orientation is relatively random in the central portion of the width direction W of the topsheet 2, the liquid excrement can be spread out in a substantially concentric manner, and since the fiber orientation is formed in the longitudinal direction L at both end portions of the width direction W of the topsheet 2, the liquid excrement reaching the both end portions can be spread out in the longitudinal direction L. That is, the sanitary napkin 1 can be used as a whole in the planar direction, and can exhibit more excellent absorption performance. In addition, since the number of fibers exposed from the edge is reduced at both ends of the top sheet 2 in the width direction W, friction against the skin of the wearer can be reduced, and the skin contact can be made smoother.

The fiber orientation of the topsheet 2 of the sanitary napkin 1 may not be formed so that the orientation in the longitudinal direction L is relatively large at both ends in the width direction W.

As shown in fig. 1, the sanitary napkin 1 has a excretory opening abutment region XA set at a position slightly forward of the center portion in the longitudinal direction L and at a position at the center portion in the width direction W in plan view. The excretory opening contact region XA is a region that faces or contacts the excretory opening of the wearer when the sanitary napkin 1 is worn in a menstrual period, and is generally set according to the type and use of the absorbent article. The excretory opening contact region XA is set at a position slightly forward of the center portion of the absorbent body 4 in the longitudinal direction L, for example, at a length of about 1/4 to 1/2 of the total length of the absorbent body 4 in the longitudinal direction L, and at a position substantially at the center portion of the absorbent body 4 in the width direction W, at a width of about 1/2 to 1/3 of the total length of the absorbent body 4 in the width direction W.

In the case where the absorbent article includes the wing portions as in the sanitary napkin 1 described above, the excretory opening contact region is usually set so as to overlap with the wing portions in the width direction, and for example, the excretory opening contact region may be set so that the center position in the longitudinal direction of the excretory opening contact region substantially overlaps with the center position in the longitudinal direction of the wing portions in the width direction.

(compressing section)

In the present embodiment, as shown in fig. 1, the sanitary napkin 1 includes a pair of compressing portions (compressing grooves) 12, 12 located on both outer sides in the width direction W with respect to the excretory opening contact region XA and extending continuously or intermittently along the longitudinal direction L.

As shown in fig. 1, in the present embodiment, the sanitary napkin 1 further includes: a pair of compressing portions (compressing grooves) 13, 13 located on the rear side of the pair of compressing

portions

12, 12 in the longitudinal direction L and extending along the longitudinal direction L; compression portions (compression grooves) 11, 14 located on the front side and the rear side in the longitudinal direction L with respect to the excretion portion contact region XA, respectively, and having a heart-shaped annular shape; and a plurality of compression portions 15 in a dot shape in the drain port abutment region XA.

The compressed portions 11 to 15 are formed by compressing the topsheet 2 and the absorbent body 4 in the thickness direction T by a processing method such as embossing. That is, the topsheet 2, the auxiliary sheet 5, and the absorbent body 4 (specifically, the skin-side core covering section 4b and the absorbent core 4a of the absorbent body 4) are compressed in the thickness direction T. As shown in fig. 2, each compression unit includes: a low-density portion LPA that is formed at a shallow depth from the skin-side surface of the front sheet 2 by being slightly compressed and has a relatively low fiber density; and a high-density portion HPA formed at a deep position from the skin-side surface of the topsheet 2 by being strongly compressed and having a relatively high fiber density. The low-density portion LPA and the high-density portion HPA may be bottom portions at shallow depths and bottom portions at deep depths in the respective compression portions.

As shown in fig. 2, the low-density parts LPA and the high-density parts HPA of the compression parts 11 to 15 are located inside the absorbent core 4a, but the high-density parts HP may reach the core-covering part 4b on the non-skin side.

The shape of the compressed parts 11 to 15 is not particularly limited, and any shape can be adopted according to the desired liquid diffusibility, deformation conductivity, strength, and the like.

The sanitary napkin 1 may not include the compressed parts 11 to 15, but preferably includes at least one of the compressed parts 11 to 15.

Sanitary napkin 1 (for physiological period)More specifically, the top sheet 2) has a compressed portion depressed from the skin-side surface in the thickness direction T, and this compressed portion can hold the water-retentive fibers F in the top sheet 2₁Thereby making it more difficult to produce the water-retentive fiber F₁The fuzzing of (1).

Further, in the present embodiment, the thermoplastic resin fibers F of the second fiber layer 2b₂At least a part of the compressed parts 11 to 15 is exposed on the surface of the inner side of the compressed part. When the sanitary napkin 1 has such a structure, the thermoplastic resin fibers F₂The water-retentive fibers F of the first fiber layer 2a can be retained even in the compressed part by being present in the first fiber layer 2a so as to be exposed on the inner surface of the compressed part₁Stably held in the thermoplastic resin fiber F₂In the meantime. Thus, the water-retentive fibers F are less likely to be formed in the compressed portion₁The raised fuzz can improve the skin contact property of the first fiber layer 2a in the compressed part. Further, the thermoplastic resin fibers F having no water retentivity in the second fiber layer 2b are formed₂Is present in the first fiber layer 2a in the compressed part, it is possible to promote the passage of liquid excrement from the first fiber layer 2a in the compressed part through the thermoplastic resin fibers F₂The liquid excrement can be transferred more stably to the absorbent body 4 (and the auxiliary sheet 5) because of the transfer to the second fiber layer 2 b.

The sanitary napkin 1 may be formed of the thermoplastic resin fibers F₂The surface of the inner side of the compression part is not exposed.

Further, in the present embodiment, the thermoplastic resin fibers F of the second fiber layer 2b₂At least a part of the low-density portion LPA is exposed on the surface of at least one of the compression portions 11 to 15. When the sanitary napkin 1 has such a structure, the thermoplastic resin fibers F₂The water-retentive fibers F of the first fiber layer 2a in the low-density portion LPA can be retained by being present in the first fiber layer 2a so as to be exposed on the surface of the low-density portion LPA₁Stably held in the thermoplastic resin fiber F₂Between. This makes it possible to prevent the water-retentive fibers F from being easily formed in the low-density portion LPA₁The resulting fuzz can improve the skin contact property of the first fiber layer 2a in the low density portion LPA. Further, the thermoplastic resin fibers F having no water retentivity in the second fiber layer 2b are formed₂Is present in the first fiber layer 2a in the low-density portion LPA, it is possible to promote the passage of liquid excrement from the first fiber layer 2a in the low-density portion LPA through the thermoplastic resin fibers F₂The liquid excrement can be transferred more stably to the absorbent body 4 (and the auxiliary sheet 5) because of the transfer to the second fiber layer 2 b.

The sanitary napkin 1 may be formed of the thermoplastic resin fibers F₂Is not exposed on the surface of the low-density portion LPA.

(concave-convex structure)

In the present embodiment, the top sheet 2 has an uneven structure as shown in fig. 4.

As shown in fig. 4 (b), the first fiber layer 2a has an upper first surface 2aE on the upper side (skin side) and a lower first surface 2aF on the lower side (non-skin side) in the thickness direction T, and the second fiber layer 2b has an upper second surface 2bE on the upper side and a lower second surface 2bF in the thickness direction T. The first lower surface 2aF of the first fiber layer 2a and the second upper surface 2bE of the second fiber layer 2b are virtual boundaries between the two fiber layers, but are not strict boundaries because some of the fibers of the two fiber layers are entangled and enter each other in the other fiber layer.

The first fiber layer 2a has: a plurality of projections 21 continuously extending along the longitudinal direction L and arranged at predetermined intervals in the width direction W, and formed by the first upper surface 2aE protruding upward (toward the skin); and a plurality of concave portions 22 that extend continuously along the longitudinal direction L, are arranged between the mutually adjacent convex portions 21, and are formed by the first upper surface 2aE being depressed downward (non-skin side).

When the topsheet 2 has such a specific uneven structure including the plurality of protrusions 21 and the plurality of recesses 22, the contact area between the skin-side surface of the topsheet 2 and the skin of the wearer becomes smaller, and therefore, the topsheet can be further providedFurther reducing the amount of the thermoplastic resin fibers F contained in the topsheet 2 to be applied to the wearer's skin₂Water-retentive fiber F₁And the possibility of uncomfortable irritation due to fuzz.

In the present embodiment, each of the plurality of projections 21 has a solid structure as shown in fig. 4 (b). As described above, if each of the plurality of protrusions 21 has a solid structure, each of the protrusions 21 is less likely to be crushed, and the liquid transfer property from each of the protrusions 21 which are likely to come into contact with the body of the wearer to the absorbent body 4 is excellent, so that the dryness of the surface of each of the protrusions 21 can be improved.

On the other hand, the second fiber layer 2b has a substantially flat structure except for a later-described recessed portion 23 formed by compression. However, the second upper surface 2bE of the second fiber layer 2b may slightly bulge upward in the thickness direction T at a position corresponding to the projection 21.

Similarly to the first fiber layer 2a (only in the direction opposite to the thickness direction T), the second fiber layer 2b may have: a plurality of projections extending continuously along the longitudinal direction L and arranged at predetermined intervals in the width direction W, and formed by the second lower surface 2bF projecting downward (non-skin side); and a plurality of concave portions that extend continuously along the longitudinal direction L, are arranged between the convex portions adjacent to each other, and are formed by the second lower surface 2bF being depressed upward (skin side). In this case, the positions of the projections 21 and the recesses 22 of the first fiber layer 2a preferably correspond to the positions of the projections and the recesses of the second fiber layer 2b in the thickness direction T.

The first fiber layer 2a and the second fiber layer 2b are joined to each other by interweaving. Examples of the interlacing method include a spunlace method (spunlace) and a spunjet method (spunjet). However, the interleaving method is not limited to this example, and other interleaving methods such as an air-through method (airthrough) may be used.

In the present embodiment, the relationship of S1 < S3 < S2 is satisfied where the fiber density of the top 21T of the convex portion 21 is S1, the fiber density of the bottom 22B of the concave portion 22 is S2, and the fiber density of the region MP between the top 21T of the convex portion 21 and the bottom 22B of the concave portion 22 is S3.

When the sanitary napkin 1 has such a configuration, in the topsheet 2, a capillary phenomenon easily acts from the top 21T of the convex portion 21 having a sparse (low density) fiber density S1 toward the bottom 22B of the concave portion 22 having a dense (high density) fiber density S2 via the region MP having a medium (medium) fiber density S3, and therefore, the liquid excrement excreted onto the skin-side most surface of the topsheet 2 (i.e., the top 21T of the convex portion 21 or the vicinity thereof) can be more easily drawn into the bottom 22B of the concave portion 22 located in the vicinity of the non-skin-side surface of the topsheet 2. This enables the liquid excrement to be transferred more stably from the skin-side surface of the topsheet 2 to the absorbent body 4 (and the auxiliary sheet 5) through the non-skin-side surface of the topsheet 2.

Further, by setting the above fiber density gradient (S1 < S3 < S2) in the top sheet 2, the liquid excrement which is absorbed once can be prevented from being rewet, and the fiber density of the protrusions 21 is reduced to provide a soft touch to the wearer, so that the top sheet 2 can improve the skin-contactability and the absorption performance.

The sanitary napkin 1 may not have the above-described uneven structure on the topsheet 2, and may not have the above-described fiber density gradient.

In the present embodiment, as shown in fig. 4, the top sheet 2 has a plurality of concave portions 23 formed by compressing the first fiber layer 2a and the second fiber layer 2b in the thickness direction T by a processing method such as embossing in the plurality of concave portions 22. The plurality of recessed portions 23 are disposed intermittently at equal intervals or at unequal intervals along the longitudinal direction L in each recessed portion 22.

The concave portions 23 may be arranged in the same straight line along the longitudinal direction L in the concave portions 22 adjacent to each other in the width direction W, or may not be arranged in the same straight line. In the present embodiment, the plurality of recessed portions 23 are arranged in a lattice shape with respect to the recessed portions 22 as shown in fig. 4 (a). The shape of each of the plurality of recessed portions 23 in a plan view is not particularly limited, and may be an elliptical shape as in the present embodiment, or may be any other shape.

When the sanitary napkin 1 has such a structure, the first fiber layer 2a and the second fiber layer 2b are fixed in the thickness direction T by compression in each of the depressions 23 of the plurality of depressions 23 (that is, the water-retentive fibers F of the first fiber layer 2a)₁Compressed), thereby being less likely to generate water-retentive fibers F₁The resulting fuzz can maintain the skin-contactability of the top sheet 2 more satisfactorily.

The sanitary napkin 1 may not have such a plurality of depressions 23 in the topsheet 2.

(auxiliary sheet)

In the present embodiment, as shown in fig. 1, the auxiliary sheet 5 has a vertically long planar shape of a substantially rectangular shape extending in the longitudinal direction L from the longitudinal direction end on the front side to the longitudinal direction end on the rear side of the sanitary napkin 1 in a planar view. As shown in fig. 2, the auxiliary sheet 5 is disposed between the topsheet 2 and the absorbent body 4 in the thickness direction T of the sanitary napkin 1 for menstrual period, and is constituted by a liquid-permeable sheet-like member that transfers liquid excreta that has passed through the topsheet 2 to the absorbent body 4 on the non-skin side.

The liquid-permeable sheet-like member that can be used as the auxiliary sheet 5 is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include a liquid-permeable nonwoven fabric, a woven fabric, and a composite sheet formed by laminating these.

In the present embodiment, the auxiliary sheet 5 positioned on the non-skin side of the top sheet 2 is joined to each of the plurality of concave portions 22 of the top sheet 2 (more specifically, the second lower surface 2bF corresponding to each concave portion 22) by an arbitrary joining method such as an adhesive or a thermal welding method. In this way, if the auxiliary sheet 5 and the surface sheet 2 are joined to each other in each of the plurality of concave portions of the surface sheet 2, the water-retentive fibers F can be retained at the joined portion of the auxiliary sheet 5 and the surface sheet 2₁Thereby making it more difficult to produce the water-retentive fiber F₁The fuzzing of (1).

Further, as shown in fig. 2, the auxiliary sheet 5 in the present embodiment has a shape slightly larger than the front sheet 2 in the width direction W, and a pair of

annular portions

5L, 5L are formed at both ends in the width direction W. The pair of

annular portions

5L, 5L are formed by annularly folding both end portions of the auxiliary sheet 5 in the width direction W toward the inner side and the non-skin side (lower side in the thickness direction T) of the auxiliary sheet 5 in the width direction W.

The folded-back auxiliary sheet 5 has both ends sandwiched between the front sheet 2 and the pair of side sheets 6, and is joined to a pair of inner ends of the pair of

side sheets

6, 6 facing each other via a pair of adhesive sections (not shown) intermittently or continuously extending in the longitudinal direction L. The annular portion 5L does not include an elastic member.

The both end portions of the folded-back auxiliary sheet 5 are respectively configured such that the back surfaces of the annular portions 5L (i.e., the non-skin-side surfaces of the auxiliary sheet 5 before being folded back) are joined to each other via a pair of adhesive portions intermittently or continuously extending along the longitudinal direction L.

In general, in a surface sheet containing a large amount of water-retentive fibers, when the edges thereof are rubbed, the water-retentive fibers are easily loosened and detached from the edges thereof, but in the present embodiment, the dimension in the width direction W of the auxiliary sheet 5 is larger than the dimension in the width direction W of the surface sheet 2, that is, in the auxiliary sheet 5, portions of the auxiliary sheet 5 located outside the edges in the width direction W of the surface sheet 2 are extended outward in the width direction W to form a pair of extended portions, and further, as the pair of extended portions, the pair of

annular portions

5L, 5L are formed at the ends in the width direction W of the auxiliary sheet 5, so that the sanitary napkin 1 can receive a force received from the thighs of the wearer by the pair of

annular portions

5L, 5L (pair of extended portions), and can make the edges in the width direction W of the surface sheet 2 less likely to rub against the thighs, thereby the water-retentive fiber F can be hardly produced₁The surface sheet 2 is loosened and removed from both end edges in the width direction W.

Further, when the pair of

annular portions

5L and 5L are used as the pair of extending portions, the sanitary napkin 1 can softly receive the force received from the thighs of the wearer by the cushioning effect of the pair of

annular portions

5L and 5L, and can improve the feeling of touch to the wearer. Especially water-retaining fiber F₁Is cottonIn the case of the fiber, the above-described effect is remarkable.

In the present embodiment, the auxiliary sheet 5 has a fiber density higher than that of the second fiber layer 2 b. When the sanitary napkin 1 has such a structure, the liquid excrement drawn into the second fiber layer 2b can be transferred more stably to the auxiliary sheet 5 by capillary action, and therefore the liquid excrement can be transferred more stably from the topsheet 2 to the absorbent member 4 via the auxiliary sheet 5, and as a result, the skin-contactability of the topsheet 2 can be improved, and the absorption performance can be improved.

The sanitary napkin 1 may not include the auxiliary sheet 5 or the annular portion 5L.

The auxiliary sheet 5 contains water-retentive fibers F corresponding to the top sheet 2₁When the top sheet 2 contains cellulose fibers (preferably cotton fibers), the auxiliary sheet 5 preferably contains cellulose fibers (preferably cotton fibers). When the sanitary napkin 1 has such a structure, the water-retentive fibers F having high liquid diffusibility₁Preferably, the cellulose-based fibers, more preferably the cotton fibers are present so as to be in communication with the auxiliary sheet 5 from the first fiber layer 2a of the topsheet 2 via the second fiber layer 2b, and therefore, liquid diffusion of liquid excrement by these fibers enables the liquid excrement to be transferred more stably from the topsheet 2 to the absorbent body 4 via the auxiliary sheet 5, and as a result, the skin-contactability of the topsheet 2 can be improved, and the absorption performance can be further improved.

The sanitary napkin 1 may be configured such that the auxiliary sheet 5 does not contain water-retentive fibers, cellulosic fibers, or cotton fibers. In this case, for example, a nonwoven fabric made of thermoplastic resin fibers can be used as the auxiliary sheet 5.

In the present invention, the size, shape, thickness, and the like of the auxiliary sheet are not particularly limited as long as the effects of the present invention are not impaired, and any size, shape, thickness, and the like according to the desired absorption performance, flexibility, and the like can be adopted.

(absorber)

In the above-described embodiment, as shown in fig. 1, the absorbent member 4 is disposed across the longitudinal center line C of the sanitary napkin 1 in plan view_LAnd a center line C in the width direction_WEach of the two center lines extends over a wide range in the longitudinal direction L and the width direction W, and the absorbent body 4 has a vertically long planar view shape in which both end portions in the longitudinal direction L protrude so as to draw a circular arc outward in the longitudinal direction L. As shown in fig. 2, the absorbent body 4 is disposed between the topsheet 2 and the backsheet 3 (more specifically, between the auxiliary sheet 5 and the backsheet 3) in the thickness direction T of the sanitary napkin 1 for physiological use, and is formed of a water-absorbent member having predetermined liquid-absorbing performance and liquid-retaining performance, which is capable of absorbing and retaining liquid excreta such as menstrual blood that has passed through the topsheet 2.

In the present invention, the water-absorbent member that can be used as the absorbent body is not particularly limited as long as it can absorb and retain at least liquid excreta such as menstrual blood, and any water-absorbent member known in the art can be used. Examples of such a water-absorbent member include a member in which at least one absorbent core made of an arbitrary water-absorbent material is covered with a core covering sheet such as a hydrophilic tissue. Here, examples of the water-absorbent material constituting the absorbent core include hydrophilic fibers, super-absorbent polymers, and the like, and more specifically, examples thereof include: pulverizing cellulose fiber such as pulp, cotton, rayon, and acetate; a granular material comprising a highly absorbent polymer such as a sodium acrylate polymer; and mixtures of any combination of the above materials.

In the above-described embodiment, the absorbent member 4 is constituted by the absorbent core 4a made of a water-absorbent material and the core covering section 4b covering the absorbent core 4 a.

When the top sheet 2 contains a cellulose fiber (preferably a cotton fiber), the absorbent body 4 preferably contains a cellulose fiber (preferably a cotton fiber) corresponding to the top sheet 2. In this case, it is preferable that a part of the cellulose fibers contained in the top sheet 2 contact the cellulose fibers contained in the absorbent body 4. When the sanitary napkin 1 has such a structure, since the cellulose-based fibers having high liquid diffusibility are present in a square form extending from the first fiber layer 2a of the topsheet 2 to the absorbent body 4 through the second fiber layer 2b (and, depending on the case, through the auxiliary sheet 5), the liquid diffusion of the liquid excrement by the cellulose-based fibers allows the liquid excrement to directly diffuse from the topsheet 2 to the absorbent body 4, and as a result, the absorption performance can be further improved.

The sanitary napkin 1 may be configured such that the absorbent member 4 does not contain cellulose fibers or cotton.

In the present invention, the shape, various sizes, square meter weight, and the like of the absorber in plan view are not particularly limited as long as they can be used as the absorber of the absorbent article, and any shape (for example, a rectangle, an oval, an hourglass shape, and the like), various sizes, square meter weight, and the like in plan view according to desired absorption performance, flexibility, strength, and the like can be adopted.

In the present invention, when the absorbent article has a predetermined absorption performance as a whole due to a constituent member (for example, a topsheet) other than the absorbent body, the absorbent article may not necessarily include such an absorbent body.

(side sheet)

In the above-described embodiment, as shown in fig. 1, the pair of

side sheets

6 and 6 has a pair of belt-like shapes extending in the longitudinal direction L at both end portions in the width direction W of the sanitary napkin 1 in a plan view. The pair of

side sheets

6, 6 are positioned on the non-skin side of the topsheet 2 at both ends in the width direction W of the sanitary napkin 1 for physiological use, and are formed of hydrophilic or hydrophobic sheet-like members that function as follows: the liquid excrement supplied to the skin-side surface of the topsheet 2 is prevented from leaking to the outside in the width direction W of the sanitary napkin 1, and is diffused along the longitudinal direction L.

The hydrophilic or hydrophobic sheet-like member usable as the side sheet 6 is not particularly limited as long as it functions as a side sheet, and examples thereof include a nonwoven fabric made of hydrophilic or hydrophobic fibers, a nonwoven fabric subjected to hydrophilization treatment or hydrophobic treatment, and a synthetic resin film having air permeability.

In the sanitary napkin 1 of the present embodiment, the dynamic friction coefficient of the pair of

side sheets

6 and 6 when wet is lower than the dynamic friction coefficient of the top sheet 2 when wet. By providing the pair of

side sheets

6 and 6 which are likely to come into contact with the skin around the legs of the wearer with a lower coefficient of dynamic friction than the top sheet 2 having excellent skin-contactability, the sanitary napkin 1 for physiological use can provide smoother skin-contactability.

Here, the dynamic friction coefficient in the wet state can be measured by the following method.

(1) The front sheet and the side sheet of the absorbent article were cut to obtain a sample having a width direction of 40mm and a length direction of 80 mm. When the above-mentioned sheet cannot be separated by an adhesive such as a Hot Melt Adhesive (HMA) type adhesive, the adhesive is washed off with toluene and then dried in the atmosphere for 24 hours.

(2) The end 10mm in the longitudinal direction of each sample was fixed to a horizontal plate by using an adhesive tape (Aikoku corporation, strength in the field, tape 0.26mm thick, 50mm wide, 25m long roll).

(3) Each sample was provided with a plain-weave muslin (50 mm. times.40 mm, JIS L0803 standard color fastness test white cloth, general consortium Japan standards Association, single fiber cloth) having 10mm ends joined to a digital load cell (Nissan electric products, FGP-0.5 (FGP-2)) over the entire surface. Further, a rectangular parallelepiped 525g weight having a bottom surface of 35mm × 25mm was placed thereon.

(4) The muslin cloth which was wetted substantially uniformly with a predetermined amount of ion-exchanged water was moved 30mm at a speed of 100 mm/min on the sheet, and the maximum value indicated at this time was taken as the dynamic friction coefficient. At this time, the muslin was in contact with the skin-side surface of each sample.

In this measurement method, the wet skin of the wearer is reproduced by wetting the muslin cloth, and 60% of the moisture content of the skin when wet is targeted as the amount of moisture to be reproduced.

Therefore, the predetermined amount of ion-exchanged water was set to 60 mass% based on the mass of the scrim. Specifically, the plain weave muslin was 50g/m at 40 mm. times.50 mm²In the case of (2), the predetermined amount of ion-exchanged water was 0.06mL (50 g/m)²×0.04m×0.05m×60％)。

When the sheet cannot be selected in the width dimension described above, a sample is selected and measured in the maximum width that can be selected. The sample was placed on the sample holder so as to be within a sheet area and to be 30g/cm²And a plain muslin cloth having a weight width of +10mm (attachment portion of the digital load cell), and moving them on the sheet at a speed of 100 mm/min for a maximum distance, the maximum value shown at this time was set as the coefficient of dynamic friction.

In the present embodiment, the dynamic friction coefficient of the top sheet 2 when wet is 0.80, and the dynamic friction coefficient of the side sheet 6 when wet is 0.49. The difference between the dynamic friction coefficient of the surface sheet 2 and the dynamic friction coefficient of the side sheet 6 may be, for example, 0.1 to 0.25. If the difference between the dynamic friction coefficients is within such a range, the wearer can easily feel the difference in surface properties between the surface sheet 2 and the side sheet 6.

The pair of

side sheets

6 and 6 having a low coefficient of dynamic friction may be formed by using a low-friction material as a material for forming the side sheets 6 and 6 (for example, a constituent fiber of a nonwoven fabric) or by covering a skin-side surface of a known sheet member used as a side sheet with a low-friction material.

The low-friction material that can be used for the side sheet is not particularly limited, and examples thereof include olefin resins such as polyethylene and polypropylene, resins having a low coefficient of friction such as silicone resins and fluororesins such as polytetrafluoroethylene, and resin compositions containing these resins.

The dynamic friction coefficient of the pair of

side sheets

6 and 6 when wet may not be lower than the dynamic friction coefficient of the top sheet 2 when wet.

In the present invention, the shape, various sizes, and the like of each of the pair of side sheets in a plan view are not particularly limited as long as the side sheets can be used as the side sheets of the absorbent article, and any shape, various sizes, and the like in a plan view can be adopted depending on the desired leakage preventing performance, absorption performance, and the like.

In addition, since the absorbent article includes such a pair of side sheets, the absorbent article of the present invention does not necessarily have to include such a pair of side sheets.

(Back sheet)

In the sanitary napkin 1 of the above-described embodiment, as shown in fig. 1, the back sheet 3 has a vertically long planar view shape extending in the longitudinal direction L from the longitudinal end on the front side of the sanitary napkin 1 toward the longitudinal end on the rear side and extending in the width direction W from the width end on one side in the width direction W of the sanitary napkin 1 toward the width end on the other side in the width direction W in a planar view. As shown in fig. 2, the back sheet 3 is configured by a liquid-impermeable sheet member that is disposed at a position other than the skin side in the thickness direction T of the sanitary napkin 1 and functions to prevent liquid excreta that has permeated through the absorbent body 4 or seeped out from the absorbent body 4 from leaking to the outside of the sanitary napkin 1.

The liquid-impermeable sheet member that can be used as the back sheet 3 is not particularly limited as long as it functions to prevent permeation of liquid excrement such as menstrual blood discharged from the wearer and to prevent leakage of the liquid excrement to the clothes of the wearer, and any liquid-impermeable sheet member such as: a hydrophobic nonwoven fabric formed of an arbitrary hydrophobic thermoplastic resin fiber (for example, polyolefin fibers such as PE and PP, polyester fibers such as polyethylene terephthalate (PET), and various conjugate fibers such as a core-sheath conjugate fiber); a porous or nonporous resin film formed of a hydrophobic thermoplastic resin such as PE or PP; a laminate obtained by bonding a nonwoven fabric to the resin film; SMS nonwoven fabric and the like.

The shape, various sizes, square meter weight, and the like of the back sheet 3 in plan view are not particularly limited as long as they can be used as a back sheet, and any shape, various sizes, square meter weight, and the like in plan view can be adopted depending on the desired leakage-proof performance, air permeability, strength, and the like.

In the sanitary napkin 1 of the present embodiment, the top sheet 2 is bonded to the auxiliary sheet 5 with an adhesive (e.g., a hot-melt adhesive), the portions of the auxiliary sheet 5 and the pair of

side sheets

6 and 6 that face the absorbent body 4 are bonded to the absorbent body 4 with an adhesive, and the portions of the pair of side sheets 6 and the absorbent body 4 that face the back sheet 3 are bonded to the back sheet 3 with an adhesive.

(adhesive part)

In the present embodiment, as shown in fig. 2, the sanitary napkin 1 further includes a plurality of adhesive sections 7 and a pair of

adhesive sections

8, 8 on the surface of the back sheet 3 on the non-skin side for fixing the sanitary napkin 1 to the clothing of the wearer (e.g., underwear).

The plurality of adhesive sections 7 are arranged on the non-skin-side surface of the back sheet 3 so as to overlap the absorbent body 4 in the thickness direction T, and have a shape in plan view of a plurality of stripes (a plurality of substantially rectangular shapes) that extend continuously along the longitudinal direction L and are arranged intermittently in the width direction W.

The pair of

adhesive portions

8, 8 are disposed on the non-skin side surface of the back sheet 3 so as to overlap the pair of

wing portions

9, 9 in the thickness direction T, and have a substantially rectangular shape in plan view that extends continuously along the longitudinal direction L.

The

adhesive parts

7 and 8 are not particularly limited as long as they can fix the sanitary napkin 1 to the clothing of the wearer, and may be formed of any adhesive such as a styrene polymer.

In addition, since the absorbent article includes such a pressure-sensitive adhesive portion, the absorbent article of the present invention does not necessarily have to include such a pressure-sensitive adhesive portion.

[ production method ]

Next, a method for producing the topsheet 2 of the sanitary napkin 1 according to the above-described embodiment will be described as an example.

(second Web Forming Process)

First, the water-retentive fibers F for forming the second fiber layer 2b₁And thermoplastic resin fiber F₂A first card (for example, a dry roller card using a single card or a double card) is fed to form a second web corresponding to the second fiber layer 2 b. The second web is conveyed by a conveying device along a conveyance direction MD.

(first Web Forming Process)

Then, the water-retentive fibers F for forming the first fiber layer 2a are bonded₁A second card (a dry roller card similar to the first card) is supplied to form a first web corresponding to the first fiber layer 2 a.

(fiber Web laminating Process)

The formed first web is laminated on the second web being conveyed by the conveying device. Thereby, a composite web having a two-layer structure in which the first web and the second web are laminated is formed.

The ratio of each fiber in each web can be controlled by the ratio of the raw material fiber supplied to each carding machine.

(interlacing step)

Next, the composite web having the two-layer structure is subjected to hydroentanglement by a hydroentanglement processor, so that the fibers in the composite web are hydroentangled with each other. Thereby, a composite fiber sheet (spunlace nonwoven fabric) was formed.

In this way, the fibers in the composite web are integrally entangled by water flow entanglement, and thus the water-retentive fibers F such as cotton fibers are less likely to be generated₁Loosening and falling off, and good skin contact properties can be easily obtained.

Here, the above-described hydroentangling process is a process of: a high-pressure water jet is jetted from the upper surface side of a composite fiber web placed on a continuously moving web belt, and fibers in the composite fiber web are entangled with each other by the action of the water jet.

The properties of the composite fiber sheet obtained by the hydroentangling process can be appropriately adjusted depending on the mass of each web, the hole diameter of the jet nozzle, the number of holes (pitch) of the jet nozzle, the moving speed of the web, and the like.

The method of forming the fiber web corresponding to each fiber layer is not limited to the above-described method, and for example, a wet method or the like may be used. The method of bonding the web is not limited to the above-described method, and for example, a hot air method (i.e., a method in which the composite web is conveyed to a heating device and fibers in the composite web are entangled with each other by heated air in the heating device), a needle punching method, or the like may be used.

(drying Process)

The composite fiber sheet having passed through the spunlace treatment machine is conveyed to a dryer (heated hot air furnace) and dried by hot air.

(Heat treatment Process)

The dried conjugate fiber sheet is then conveyed to a heat treatment apparatus (hot-air furnace) and subjected to heat treatment with hot air at a predetermined temperature. By this heat treatment, at least a part of the thermoplastic resin fibers F in the composite fiber sheet₂Melting, the melt F_2MThe water-retentive fibers F flowing through the composite fiber sheet and adhering to the portions corresponding to the first fiber layers 2a₁Interweaving part P in the composite fiber sheet_EWater-retaining fiber F of (A)₁And so on. Thereby, at least a part of the water-retentive fibers F contained in at least the portion corresponding to the first fiber layer 2a₁At the interweaving part P of the fibres_EAt least a part of the interleaved part P_EIs formed of thermoplastic resin fibers F₂Melt F of_2MAnd (6) covering.

The heat treatment is carried out under conditions that allow the thermoplastic resin fibers F to be formed₂The melting is not particularly limited, but in the thermoplastic resin fiber F₂In the case of a composite fiber such as a core-sheath composite fiber or a side-by-side composite fiber, it is preferable to use a melting point that exposes only the surface of the composite fiberA low temperature condition under which the resin component (for example, the resin component constituting the sheath portion in the case of the core-sheath type composite fiber, and the resin component on one side in the case of the side-by-side type composite fiber) melts.

Further, the above-mentioned drying after the hydroentangling treatment and the apparatus (i.e., the dryer and the heat treatment apparatus) used for the heat treatment after the drying may be used in combination.

(shaping step)

Next, the composite fiber sheet after the heat treatment is conveyed in the conveyance direction MD and supplied to a shaping device. Here, the shaping device includes a pair of shaping rollers having a concave portion and a convex portion extending in the circumferential direction on the outer peripheral surface and engaging with each other, and the composite fiber sheet after the heat treatment is sandwiched between the concave portion and the convex portion of the pair of shaping rollers and shaped into the specific concave-convex structure extending in the conveyance direction MD.

When the surface sheet 2 does not have such a specific uneven structure, the shaping step may be omitted.

Thus, a composite shaped fiber sheet for the surface sheet 2 is formed. The topsheet 2 is formed by laminating the shaped conjugate fiber sheet and a sheet-like member for other constituent members of the sanitary napkin 1 and then cutting the laminate into the shape of the sanitary napkin 1.

The present invention can be applied to various absorbent articles such as panty liners, (light) incontinence pads, disposable diapers, and the like, in addition to the sanitary napkins of the above-described embodiments. The absorbent article of the present invention is not limited to the above-described embodiments, examples described below, and the like, and may be appropriately combined, substituted, or modified without departing from the object and spirit of the present invention.

The nonwoven fabric having the first fiber layer and the second fiber layer used for the topsheet of the absorbent article of the present invention is a nonwoven fabric which is less likely to cause uncomfortable irritation to the skin of the user and has excellent skin-contact properties, and therefore, the nonwoven fabric can be applied to other sheet-like members (for example, side sheets, exterior sheets, and the like) which require good skin-contact properties, and further, can be applied to nonwoven fabrics used for sanitary goods other than absorbent articles (for example, masks, sheets for removing dirt, masks, cosmetic sheets, and puffs (for example, cotton puffs).

In the case of application to such a nonwoven fabric, the nonwoven fabric is a nonwoven fabric having a first surface and a second surface, wherein,

the nonwoven fabric is provided with:

a first fiber layer containing water-retentive fibers and forming the first surface of the nonwoven fabric; and

a second fiber layer containing thermoplastic resin fibers and water-retentive fibers, the second surface of the nonwoven fabric being formed adjacent to the second surface of the first fiber layer,

Examples

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

The surface sheet (example) usable in the absorbent article of the present invention and the surface sheet (comparative example) not satisfying the constituent requirements of the present invention were produced, and the occurrence of the above-described fluff was verified.

Example 1

First, cotton fibers (fiber length 5mm to 35mm, square meter weight 16 g/m) were prepared as the water-retentive fibers and the thermoplastic resin fibers for forming the second fiber layer, respectively²) And a core-sheath type composite fiber (core: PP, sheath part: PE, fiber length 38mm, weight in square meter 4g/m²) Feeding the fibers to a first carding machine to form second fibers corresponding to the second fiber layerWeb (second web forming process). The mixing ratio (mass ratio) of the cotton fibers to the core-sheath composite fibers in the second fiber web was set to be cotton fibers: core-sheath composite fiber 60: 40.

next, as water-retentive fibers for forming the first fiber layer, only cotton fibers (fiber length 20mm to 35mm, weight in square meter 10 g/m) were prepared²) The cotton fibers are supplied to a second carding machine to form a first web corresponding to the first fiber layer (first web forming step).

Then, the formed first web is laminated on the second web being conveyed by the conveyor to form a composite web having a two-layer structure in which the first web and the second web are laminated (web laminating step), and then the composite web is subjected to hydroentanglement by a hydroentangling machine to water-jet-entangle the fibers in the composite web, thereby obtaining a composite fiber sheet (spunlace nonwoven fabric) (interlacing step).

The conjugate fiber sheet having passed through the hydroentangling machine was conveyed to a dryer (heated hot air furnace) and dried with hot air at 70 ℃.

Further, the dried conjugate fiber sheet was conveyed to a heat treatment device (hot-air furnace) and subjected to heat treatment with hot air at 130 ℃, so that the cotton fibers were covered with a melt of the core-sheath conjugate fiber (specifically, a melt of PE in the sheath) at the interlaced portion between the fibers (heat treatment step).

Next, the composite fiber sheet after the heat treatment is supplied to a shaping device having a pair of shaping rollers having concave portions and convex portions engaged with each other, and shaped into a concave-convex structure extending along the conveyance direction MD by being sandwiched between the concave portions and the convex portions of the pair of shaping rollers (shaping step).

The composite shaped fiber sheet shaped into the uneven structure in this way was cut into a predetermined shape to obtain the surface sheet of example 1.

Comparative example 1

A surface sheet of comparative example 1 was obtained in the same manner as in example 1, except that the heat treatment step and the shaping step were not performed.

Comparative example 2

Except that only cotton fibers (fiber length 20 mm-35 mm, square meter weight 30 g/m) were used²) A surface sheet of comparative example 2 was obtained in the same manner as in example 1, except that the fibers used for forming the surface sheet (i.e., the surface sheet was a single-layer-structured fiber layer (cotton fiber layer) having no second fiber layer) and the heat treatment step and the shaping step were not performed.

With respect to the top sheet of example 1, the morphology in the first fiber layer was observed with a scanning electron microscope, and cotton fibers (water-retentive fibers F) were confirmed₁) At the interweaving part P of the fibres_ESheath-core type composite fiber (thermoplastic resin fiber F)₂) Melt of (2) (specifically, melt of PE of sheath part) F_2MCovering this situation. Fig. 5 shows the confirmation result (i.e., an electron micrograph of the first fiber layer in the surface sheet of example 1).

Further, the surface sheets of example 1, comparative example 1 and comparative example 2 were compared and evaluated for the occurrence of fuzz according to the following < evaluation method of fuzz by a frictional fastness test >. Fig. 6 shows the evaluation results (i.e., comparative photographs showing the occurrence of fuzz in example 1 and comparative examples 1 and 2).

Method for evaluating fuzz based on Friction fastness test

(1) A measurement sample is obtained by cutting out a measurement target region from a nonwoven fabric constituting a surface sheet with a predetermined size (for example, 80mm × 40 mm).

(2) The sample for measurement was fixed on a measuring table of a dyed article rubbing fastness tester (manufactured by Daorhiki Kagaku Kogyo Co., Ltd.).

(3) A 200g weight was attached to the upper surface of the friction terminal of the dyed part friction firmness testing machine, and a tape forming a friction surface was attached to the lower surface.

(4) The surface of the measurement sample fixed to the measurement stage is rubbed by the friction surface of the friction terminal. At this time, the number of times of reciprocating the friction terminal was 100 times and 200 times, and the moving range (reciprocating amplitude) of the friction terminal was 60 mm. The items "0T", "100T", and "200T" shown in fig. 6 indicate that the number of times of reciprocating the friction terminal in the frictional firmness test (FF) is "0 times", "100 times", and "200 times", respectively.

(5) The surface of the measurement sample after being rubbed with the rubbing terminal was observed for fluffing.

As shown in fig. 6, it is understood that the top sheet of example 1, in which the cotton fibers were covered with the melt of the core-sheath composite fibers at the interlaced portions between the fibers by applying the heat treatment, had little fluffing even after being rubbed 200 times with the rubbing terminal, and had excellent skin-contactability (see the photograph in column a in fig. 6).

On the other hand, it is found that the surface sheets of comparative examples 1 and 2, which were not subjected to the heat treatment, had fuzz and decreased skin contact properties only by 100 times of rubbing with the rubbing terminals (see photographs in columns B (comparative example 1) and C (comparative example 2) in fig. 6).

Description of the reference numerals

Sanitary napkin for physiological period (an example of an absorbent article)

2 surface sheet

2a first fibrous layer

2b second fibrous layer

3 Back sheet

4 absorbent body

5 auxiliary sheet

6 side sheet

F₁Water-retaining fiber

F₂Thermoplastic resin fiber

F_2MMelt mass

Claims

1. An absorbent article comprising a surface sheet, wherein,

the surface sheet is provided with:

2. The absorbent article of claim 1,

one thermoplastic resin fiber of the thermoplastic resin fibers is interwoven with the plurality of water-retaining fibers,

the thermoplastic resin fiber and the plurality of interweaving parts of the water-retaining fiber are covered by the melt of the thermoplastic resin fiber respectively.

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

the melt of the thermoplastic resin fibers is not exposed on the skin-side surface of the first fiber layer.

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

at least the average fiber length of the water-retentive fibers contained in the first fiber layer is shorter than the average fiber length of the thermoplastic resin fibers.

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

at least the first fibrous layer contains the average fiber length of the water-retaining fiber is 5mm or more and less than 35 mm.

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

the thermoplastic resin fiber is a composite fiber,

the resin component having a low melting point in the composite fiber is exposed on the surface of the composite fiber.

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

the top sheet has a compressed portion recessed in the thickness direction from the skin-side surface.

8. The absorbent article according to any one of claims 1 to 7, wherein,

the surface sheet has:

a plurality of protrusions extending along the longitudinal direction of the absorbent article and arranged at intervals in the width direction of the absorbent article; and

a plurality of concave portions extending in a longitudinal direction of the absorbent article and located between the convex portions adjacent to each other.

9. The absorbent article of claim 8,

the absorbent article further comprises an auxiliary sheet on the non-skin side of the topsheet,

the surface sheet is engaged with the auxiliary sheet at the plurality of recesses, respectively.

10. The absorbent article according to any one of claims 1 to 9, wherein,

the water-retaining fiber is organic cotton.

11. The absorbent article according to any one of claims 1 to 10, wherein,

the second fibrous layer has a greater fiber density than the first fibrous layer.

12. The absorbent article according to any one of claims 1 to 11, wherein,

the average distance between the fibers of the second fibrous layer is shorter than the average distance between the fibers of the first fibrous layer.

13. The absorbent article according to any one of claims 1 to 12, wherein,

the absorbent article further includes a pair of side sheets positioned on the skin side of the top sheet at both ends in the width direction,

the pair of side sheets has a lower coefficient of dynamic friction when wet than the surface sheet.