WO2022201677A1

WO2022201677A1 - Absorbent article

Info

Publication number: WO2022201677A1
Application number: PCT/JP2021/046829
Authority: WO
Inventors: 啓介長島; 湧太辰巳
Original assignee: 花王株式会社
Priority date: 2021-03-25
Filing date: 2021-12-17
Publication date: 2022-09-29
Also published as: CN115697270A; JP7093869B1; TW202237051A; JP2022149872A

Abstract

An absorbent article according to the present invention has a non-woven fabric intermediate sheet (30) disposed between a liquid-permeable surface sheet (10) and an absorber (40) in such a manner as to abut on the non-skin-contact-surface side of the surface sheet (10). The surface sheet (10) comprises an upper layer (11) disposed on the skin-contact-surface side and a lower layer (12) disposed on the non-skin-contact-surface side. The upper layer is formed by including multiple types of fibers having mutually different contact angles with respect to water. The contact angle with respect to water for fibers forming the upper layer is greater than that for fibers forming the lower layer. The intermediate sheet (30) has embossed portions. The intermediate sheet (30) has a greater areal rate of the embossed portions (15, 31) than the surface sheet (10). The contact angle with respect to water for the fibers forming the intermediate sheet (30) is greater than that for the fibers forming the surface sheet (10).

Description

absorbent article

The present invention relates to absorbent articles.

From the viewpoint of suppressing stickiness, etc., the surface sheet that forms the skin contact surface of absorbent articles such as sanitary napkins, incontinence pads, and panty liners that are used to absorb liquid discharged from the body has a liquid on the surface. is required to be difficult to remain.
As a surface sheet in which liquid hardly remains on the surface layer, a surface sheet made of nonwoven fabric having a two-layer structure of an upper layer and a lower layer is known.
For example, Patent Document 1 describes that a nonwoven fabric for absorbent articles having a first fiber layer facing the skin and a second fiber layer adjacent to the first fiber layer is used as a surface sheet for absorbent articles. there is
Further, an intermediate sheet made of non-woven fabric, which is also called a sublayer or a second sheet, is arranged under the topsheet and adjacent to the topsheet. Such an intermediate sheet is arranged for the purpose of improving the diffusibility of the liquid in the plane direction.

JP 2019-063414

The present invention has a liquid-permeable topsheet, a backsheet, and an absorbent body positioned between the topsheet and the backsheet, and has a longitudinal direction corresponding to the front-rear direction of the wearer and a width orthogonal to the longitudinal direction. direction.
The topsheet preferably comprises an upper layer arranged on the skin-contacting side and a lower layer arranged on the non-skin-contacting side. It is preferable that the upper layer includes a plurality of types of fibers having different contact angles with water. It is preferable that the contact angle with water of the fibers forming the upper layer is larger than the contact angle with water of the fibers forming the lower layer. It is preferable that an intermediate sheet made of non-woven fabric is disposed adjacent to the top sheet between the top sheet and the absorbent body. Preferably, the intermediate sheet has embossed portions, and the intermediate sheet has a larger area ratio of the embossed portions, which is the ratio of the total area of the embossed portions to the surface area of the sheet, than the surface sheet. It is preferable that the water contact angle of the fibers forming the intermediate sheet is larger than the water contact angle of the fibers forming the top sheet.

FIG. 1 is a schematic cross-sectional view of an example of a surface sheet that can be used in the absorbent article of the present invention. FIG. 2 is a schematic plan view showing an example of the surface sheet that can be used in the absorbent article of the present invention, viewed from the skin contact side. FIG. 3 is a schematic diagram showing a manufacturing method of an example of the surface sheet that can be used in the absorbent article of the present invention. FIG. 4 is a schematic cross-sectional view along the width direction of the excretion part-facing portion in one embodiment of the absorbent article of the present invention. 5(a) and 5(b) are diagrams showing an example of an intermediate sheet that can be used in the absorbent article of the present invention, where FIG. 5(a) is a schematic plan view and FIG. ) is a schematic sectional view taken along line III-III.

Detailed description of the invention

In the two-layer surface sheet, a hydrophilicity gradient is provided between the upper layer and the lower layer, and the hydrophilicity of the lower fiber layer is higher than that of the upper fiber layer, thereby promoting the migration of the liquid to the lower layer. It becomes difficult for the liquid to remain on the upper layer of the surface sheet. In order to further prevent the surface of the topsheet from becoming sticky, it is desired that the liquid be quickly transferred from not only the top layer of the topsheet but also the entire topsheet to the absorbent body.

The present invention relates to providing an absorbent article in which liquid hardly remains on the topsheet and the liquid can be quickly transferred from the topsheet to the absorbent body.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on its preferred embodiments with reference to the drawings.
The absorbent article of the present invention generally has a vertically long shape having a longitudinal direction corresponding to a direction extending from the wearer's abdomen to the back through the crotch and a width direction orthogonal thereto. This longitudinal direction corresponds to the longitudinal direction of the wearer.
The absorbent article has a crotch portion arranged in the crotch portion of the wearer and a front portion and a rear portion extending in the front and rear of the crotch portion. The crotch part has an excretory part-facing region including an excretory part-facing part that is arranged to face the wearer's excretory part such as the vaginal opening when the absorbent article is worn. They are located in the longitudinal center, the widthwise center, and the vicinity thereof.

Absorbent articles generally include a topsheet positioned on the wearer's skin-contacting side, a backsheet positioned on the non-skin-contacting side, and an absorbent body interposed between the topsheet and the backsheet. Prepare. As the surface sheet, one or a plurality of liquid-permeable sheets such as nonwoven fabrics and perforated films can be used. The surface sheet may have unevenness on the side of the skin contacting surface. For example, a plurality of convex portions can be formed in a scattered pattern on the side of the surface that contacts the skin of the topsheet. Alternatively, ridges and grooves extending in one direction may be alternately formed on the skin-contacting surface of the topsheet. For such purposes, the topsheet can also be formed using a multi-layer sheet formed by laminating two or more nonwoven fabrics in a detachable or non-peelable manner. When the surface sheet is formed with an uneven shape or a ridge-and-groove shape, the projections or ridges may have a solid structure or a hollow structure.

On the other hand, as the back sheet, for example, a liquid-impermeable or liquid-impermeable film, spunbond, meltblown, or spunbond nonwoven fabric can be used. A plurality of micropores may be provided in a liquid-impermeable or liquid-impermeable film to impart water vapor permeability to the film. For the purpose of further improving the feel of the absorbent article, a sheet having good texture such as a non-woven fabric may be laminated on the outer surface of the backsheet.

The absorber has an absorbent core. The absorbent core is, for example, a pile of hydrophilic fibers such as pulp and cellulose, a mixed pile of hydrophilic fibers and absorbent polymer, a pile of absorbent polymer, and two absorbent sheets. It is composed of a laminated structure or the like in which an absorbent polymer is carried between them. At least the skin-contacting surface of the absorbent core may be covered with a liquid-permeable core-wrap sheet, and the entire surface including the skin-contacting surface and the non-skin-contacting surface is covered with the core-wrap sheet. may As the core wrap sheet, for example, a thin paper made of hydrophilic fibers, a liquid-permeable nonwoven fabric, or the like can be used.

As used herein, the term “skin-contacting surface” refers to a surface of an absorbent article or its constituent members (for example, an absorbent body) that faces the wearer's skin when the absorbent article is worn, that is, relatively The "non-skin-contacting surface", which is the side close to the skin, is the side of the absorbent article or its constituent members opposite to the skin side when the absorbent article is worn, that is, the side relatively far from the wearer's skin. This is the side you are facing. It should be noted that the term "when worn" as used herein means a state in which the absorbent article is maintained in a normal and appropriate wearing position, that is, in a correct wearing position of the absorbent article.

In addition to the above-described topsheet, backsheet, and absorbent body, leakage-preventing cuffs extending in the longitudinal direction are arranged on both sides along the longitudinal direction of the skin-contacting surface, depending on the specific use of the absorbent article. may occur. A leak-tight cuff generally has a proximal end and a free end. The leak-proof cuff has a base end on the skin-contacting side of the absorbent article and stands up from the skin-contacting side. The leak-tight cuff is constructed from a liquid-resistant or water-repellent and breathable material. An elastic member made of rubber thread or the like may be arranged in a stretched state at or near the free end of the leak-proof cuff. When the absorbent article is worn, the contraction of the elastic member causes the leakage-preventing cuff to stand up toward the wearer's body, and the liquid excreted on the topsheet flows along the topsheet and becomes absorbent. Leakage to the outside in the width direction of the article is effectively prevented. Moreover, the absorbent article may further have an adhesive layer on the non-skin-contacting surface. The pressure-sensitive adhesive layer is used to fix the absorbent article to underwear or another absorbent article while the absorbent article is worn.

A preferred example of the surface sheet used in the absorbent article of the present invention will be described with reference to FIGS. 1 and 2. FIG.
The surface sheet 10 shown in FIGS. 1 and 2 is a liquid-permeable, two-layer sheet comprising an upper layer 11 and a lower layer 12 . In the topsheet 10, the upper layer 11 is arranged on the skin-contacting side, which is the side that contacts the wearer's skin, and the lower layer 12 is arranged on the non-skin-contacting side, which is the side opposite to the skin-contacting side. be done. The lower layer 12 is arranged in contact with the intermediate sheet 30 arranged adjacent to the non-skin-contacting side of the topsheet 10 (see FIG. 4).

As shown in FIG. 1, the surface sheet 10 has an upper layer 11 and a lower layer 12 separated by a boundary surface F. The upper layer 11 and the lower layer 12 shown in the figure have a fixed portion 15 where the

layers

11 and 12 are joined to each other, and a non-fixed portion 16 where the upper layer 11 and the lower layer 12 are not joined by the fixed portion 15. ing. A boundary surface F between the upper layer 11 and the lower layer 12 exists in the non-fixed portion 16 , but the boundary surface F does not exist in the fixed portion 15 . The fixed portion 15 in the present embodiment is formed by laminating a fiber assembly constituting the upper layer 11 and a fiber assembly constituting the lower layer to form a laminate, and embossing the laminate. The fixed portion 15 is the embossed portion of the topsheet 10 .

As shown in FIG. 1, when the fixing portion 15 that joins the upper layer 11 and the lower layer 12 to each other is formed, the surface sheet 10 has an uneven shape on the side of the skin contacting surface of the upper layer 11 . Concave portions 17 are formed in each of the upper layer 11 and the lower layer 12 of the fixing portion 15 of the topsheet 10 . Protrusions 18 are provided between the recesses 17 on the skin-contacting surface of the upper layer 11 . As will be described later, the convex portion 18 exists in a region surrounded by the fixing portion 15 forming the concave portion 17 .

As shown in FIG. 2, the surface sheet 10 includes, as the fixed portions 15, a first fixed portion row L1 and a second fixed portion row L1 and a second fixed portion row which are configured to include the fixed portions 15 inclined in opposite directions with respect to the X direction. It is preferred to have L2. A large number of first fixing portion rows L1 and second fixing portion rows L2 shown in FIG. alternately. The fixed portions 15 forming the first fixed portion row L1 and the second fixed portion row L2 shown in FIG. 2 are discontinuous lines. The X direction preferably coincides with the longitudinal direction or width direction of the absorbent article. The X direction may be a direction that is inclined with respect to both the longitudinal direction and the width direction of the absorbent article.

A plurality of groove-shaped recesses 17 are formed in the first fixing portion row L1 and the second fixing portion row L2 where the fixing portions 15 are formed so as to extend along each fixing portion row. In the region surrounded by the fixing portion 15, three types of

protrusions

18a, 18b, and 18c having different areas are formed so as to protrude toward the skin contact surface. The

protrusions

18a, 18b, and 18c may have different heights or may have the same height. Both the first convex portion 18a and the third convex portion 18c shown in the figure are diamond-shaped, and the first convex portion 18a has a larger planar view area than the third convex portion 18c. The second convex portion 18b has a parallelogram shape in plan view, and has an area in plan view intermediate between that of the first convex portion 18a and the third convex portion 18c. All of the fixing portions 15 are concave portions 17, which are thinner than the other

convex portions

18a, 18b, and 18c. The topsheet 10 shown in FIG. 2 has

convex portions

18a, 18b, and 18c with different areas in plan view formed in the sections with different areas surrounded by the fixing portions 15, so that the topsheet 10 can be excreted. This is preferable because it makes it difficult for body fluids to diffuse in one direction. In addition, in the surface sheet 10 shown in FIG. 2 , the rhombus-shaped section having the largest planar view area in the region surrounded by the fixing portions 15 has two types of sizes having a smaller planar view area than this section. Therefore, when the absorbent article having the topsheet 10 shown in FIG. The second and

third protrusions

18b and 18c present in small sections around them remain to restrict the diffusion of body fluid, which is more preferable.

The upper layer 11 of the surface sheet 10 is composed of a fiber assembly containing thermally extensible fibers. The upper layer 11 may be composed only of thermally extensible fibers, or may further contain second fibers different from the thermally extensible fibers in addition to the thermally extensible fibers. Details of the second fibers will be described later.

Examples of thermally extensible fibers include fibers that elongate due to changes in the crystalline state of the resin due to heating, and fibers that have been crimped and whose apparent length is elongated when the crimp is released. be done. By including the thermally extensible fibers in the upper layer 11, the upper layer 11 and the surface sheet 10 become bulky and three-dimensional due to the elongation of the thermally extensible fibers, and a good appearance can be exhibited.

Preferred thermally extensible fibers are composed of a first resin component and a second resin component having a melting point or softening point lower than the melting point of the first resin component, and the second resin component is continuous on part or the entire surface of the fiber. Composite fibers that exist as It is also preferable that the fibers are thermally fused with other fibers during thermal elongation. The first resin component in the thermally extensible fiber is typically a component that exhibits thermal extensibility of the fiber, and the second resin component is typically a component that exhibits thermal fusion bondability. A fiber composed of such a component is configured to be stretchable by applying a temperature lower than the melting point of the first resin component.

Examples of such thermally extensible fibers include JP-A-2004-218183, JP-A-2005-350836, JP-A-2007-303035, JP-A-2007-204899, and JP-A-2007-204901. and fibers described in JP-A-2007-204902 or JP-A-2008-101285.

Specifically, examples of the first resin component include polyolefin resins such as polypropylene (PP) (excluding polyethylene resins), polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). These may be used alone or in combination of two or more.

Also, examples of the second resin component include polyethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). These may be used alone or in combination of two or more. In addition to the polyethylene resin, other resins such as PP, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), etc. may be mixed and used. It is preferable to use only a polyethylene resin as the second resin component from the viewpoint of obtaining a bulky surface sheet having excellent texture and strength by forming thermal adhesion points where fibers are thermally fused to each other.

As a combination of the first resin component and the second resin component, PP or PET is used as the first resin component and HDPE is used as the second resin component. It is preferable in that it can be easily obtained.

The melting points of the first resin component and the second resin component are measured using a differential scanning calorimeter (DSC6200 manufactured by Seiko Instruments Inc.). A finely cut fiber sample (2 mg sample mass) is subjected to thermal analysis at a heating rate of 10° C./min to measure the melting peak temperature of each resin. A melting point is defined by its melting peak temperature. If the melting point of a resin component cannot be clearly determined by this method, the resin is defined as "a resin without a melting point". In this case, as the temperature at which the molecules of the resin component start to flow, the softening point is the temperature at which the resins are fused to such an extent that the strength of the fusion point of the fibers can be measured.

In a preferred embodiment containing a first resin component and a second resin component, the thermally extensible fiber preferably has a thermal elongation rate of 0.5 at a temperature 10°C higher than the melting point or softening point of the second resin component. % or more, more preferably 3% or more, still more preferably 5% or more, and preferably 20% or less.

The thermal elongation rate of fibers can be measured, for example, by the following method. As a measuring device, a thermomechanical analyzer TMA/SS6000 manufactured by Seiko Instruments Inc. is used. As a sample, a plurality of fibers with a fiber length of 10 mm or more are collected so that the total mass per 10 mm of fiber length is 0.5 mg. After aligning the fibers in parallel, both ends of the fibers are attached to the chucks of the apparatus so that the fibers do not slack. The distance between chucks is set to 10 mm. Then, the measurement start temperature is set to 25° C., and the temperature is raised at a rate of 5° C./min while a constant load of 0.73 mN/dtex is applied in the fiber length direction. The elongation amount of the fiber at that time is measured, and the elongation amount C (mm) at a temperature 10° C. higher than the melting point or softening point of the second resin component is measured. The elongation amount C (mm) can be calculated by subtracting the fiber length before measurement from the fiber length after measurement.
The thermal elongation rate (%) of the fiber is calculated from "(C [mm]/distance between chucks [mm]) x 100".

The lower layer 12 of the surface sheet 10 is composed of a fiber assembly that does not contain the heat extensible fibers described above or contains the heat extensible fibers at a lower mass ratio than the upper layer 11 . Specifically, the lower layer 12 is composed only of fibers other than the thermally extensible fibers, or is composed of the thermally extensible fibers and other fibers.
The upper layer 11 of the surface sheet 10 is a fiber aggregate containing heat-extensible fibers, and the lower layer of the surface sheet 10 does not contain heat-extensible fibers or contains heat-extensible fibers at a lower mass ratio than the upper layer. As a result of the assembly, the liquid is less likely to remain on the topsheet 10 . In other words, it is possible to provide a topsheet for an absorbent article in which the liquid hardly remains on the surface of the topsheet 10 and which has a good texture even after absorbing the liquid.

The surface sheet 10 is configured such that the contact angle of the fibers forming the upper layer 11 with water is larger than the contact angle of the fibers forming the lower layer 12 with water. The contact angle of the fiber with water is one index of the hydrophilicity of the fiber, and the smaller the contact angle of the fiber with water, the higher the hydrophilicity. That is, the surface sheet 10 is configured such that the constituent fibers of the lower layer 12 are more hydrophilic than the constituent fibers of the upper layer 11 .

The contact angle with water of the fibers constituting the upper layer 11 is preferably 60° or more, more preferably 65° or more, and still more preferably, provided that the contact angle with water is larger than that of the fibers constituting the lower layer 12. is 70° or more, preferably 95° or less, more preferably 90° or less, and still more preferably 85° or less. Similarly, the contact angle with water of the fibers constituting the lower layer 12 is preferably 55° or more, more preferably 60° or more, still more preferably 65° or more, and preferably 90° or less, more preferably 85° or less, more preferably 80° or less. The contact angle of the fiber with water can be appropriately adjusted, for example, by changing the raw material of the fiber or by subjecting the fiber surface to hydrophilization or hydrophobization. By adjusting the contact angle of the fiber with water within the range described above, a hydrophilic gradient is created between the upper layer 11 and the lower layer 12, so that the lower layer 12 is more hydrophilic than the upper layer 11, so that the water is excreted toward the upper layer 11 side. It is possible to make it easier for the body fluid to permeate the highly hydrophilic lower layer 12 side.

[Method for measuring contact angle with water]
The contact angle of the fiber with water can be measured, for example, by the following method. That is, the fibers located on the outer surface (skin-contacting surface) of the upper layer 11 constituting the topsheet 10 and the fibers located on the outer surface (non-skin-contacting surface) of the lower layer 12 are arranged so that the fiber length is 1 mm. Measurement samples are cut out, and the contact angle of water with respect to these measurement samples is measured. As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. Distilled water is used to measure the contact angle.
Place the measurement sample on the sample table of the contact angle meter and keep it horizontal. Set the amount of liquid ejected from the inkjet method water droplet ejection part (Cluster Technology Co., Ltd., pulse injector CTC-25 with an ejection part hole diameter of 25 μm) to 10 picoliters, and drop water droplets directly above the fibers of the measurement sample. . The state of dripping is recorded on a high-speed recording device connected to a camera placed horizontally. From the viewpoint of image analysis and image analysis later, the recording device is preferably a personal computer with a built-in high-speed capture device. In this measurement, an image is recorded every 17 msec. In the recorded video, the first image of water droplets landing on the fibers taken out of the nonwoven fabric was captured using the attached software FAMAS (software version 2.6.2, analysis method: droplet method, analysis method: θ/2 method , the image processing algorithm is non-reflection, the image processing image mode is frame, the threshold level is 200, and the curvature correction is not performed). be the contact angle. Two different contact angles are measured for each measurement sample.
The contact angles of five measurement samples (N = 5) obtained from the fibers located on the skin contact surface of the upper layer 11 are measured to one decimal place, and the arithmetic average of the measured values of a total of ten places (decimal point hereinafter rounded to the second digit) is defined as the contact angle of the fibers forming the upper layer of the surface sheet with water. The contact angles of 5 measurement samples (N = 5) obtained from the fibers located on the non-skin contact surface of the lower layer 12 were measured to one decimal place, and the arithmetic average of the measured values at a total of 10 locations ( (rounded to two decimal places) is defined as the contact angle with water of the fibers that make up the bottom layer of the topsheet. The boundary between the upper layer 11 and the lower layer 12 is defined, for example, by the contact angle of each fiber to define the existence area of each fiber assembly of the upper layer 11 and the lower layer 12 of the surface sheet 10, and the boundary between the fibers with different contact angles is the boundary surface. can be F.

As shown in FIG. 1, the upper layer 11 of the surface sheet 10 includes a plurality of types of fibers having different contact angles with water. For example, the upper layer 11 is preferably a fiber aggregate including thermally extensible fibers and second fibers different from the thermally extensible fibers, each fiber having a different hydrophilicity.
Since the fibers forming the upper layer 11 have a larger contact angle with water than the fibers forming the lower layer 12, there is an advantage that liquid residue on the surface layer of the top sheet 10 can be further reduced. In addition, since the fibers constituting the upper layer 11 of the topsheet 10 include a plurality of types of fibers having mutually different contact angles with water, the liquid is prevented from diffusing on the topsheet 10 and the liquid is prevented from spreading. Since it becomes easier to permeate the surface sheet 10 in the thickness direction, there is an advantage that the liquid hardly remains on the surface sheet 10 .
In addition, when the fibers constituting the upper layer 11 include a plurality of types of fibers having different contact angles, the upper layer 11 constitutes the lower layer 12 from the viewpoint of making it easier to express the effects of the present invention. It preferably contains 50% or more, more preferably 90% or more, of fibers having a larger contact angle with water than fibers.

The content of fibers having a larger contact angle with water than the fibers forming the lower layer 12 among the fibers forming the upper layer 11 can be measured by the following method.
[Method for measuring the content of fibers that make up the upper layer and have a larger contact angle with water than the fibers that make up the lower layer]
In a plan view of the surface sheet 10 viewed from the skin-contacting side, a predetermined range (for example, a range surrounded by a square of 3 cm x 3 cm) is determined from the excretion part-facing region, and the thickness direction is determined from the skin-contacting side of the upper layer. 5 fibers included in the range of 1 mm in , and 5 fibers included in the lower layer are taken out. For each fiber, the contact angle with water is measured by the method described above [Method for measuring contact angle with water].
Six different contact angles are measured for each measurement sample. The contact angles with water at 30 points where the fibers contained in the upper layer 11 were measured respectively and the contact angles with water at 30 points where the fibers contained in the lower layer 12 were measured were compared.
Specifically, the fibers taken out from the upper layer 11 are arranged in descending order of contact angle with water (each N=30). Similarly, the contact angles with water of the fibers taken from the lower layer 12 (each N=30) are arranged in descending order. The calculation method of "the content of fibers having a larger contact angle with water than the fibers forming the lower layer 12 among the fibers forming the upper layer 11" is as follows.
The contact angle with water of the fibers taken out from the upper layer 11 and the contact angle with water of the fibers taken out from the lower layer 12 are compared. The content rate is defined as 50% or more when 15 or more are larger than the corner. If all 30 water contact angle values of the fibers taken from the upper layer 11 are greater than the water contact angles of the fibers taken from the lower layer 12, the content is 100%.
As for the position from which the fibers are taken out from the upper layer 11 and the lower layer 12, it is desirable to select the central region (region facing the excretory part) of the absorbent article.

When two or more types of fibers constitute the lower layer 12, the fibers constituting the upper layer 11 have a larger contact angle with water than the fiber with the highest content among the fibers constituting the lower layer 12. It preferably contains 50% or more, more preferably 90% or more. Furthermore, the “fiber with the highest content” of the lower layer 12 refers to the fiber with the highest number of fibers constituting the lower layer 12, and the content of the “fiber with the highest content” is the content of the lower layer 12. It is preferably 50% or more, more preferably 80% or more, in the fiber.

From the viewpoint of further enhancing the effect that the liquid hardly remains in the surface sheet 10, the upper layer 11 contains heat-extensible fibers and second fibers different from the heat-extensible fibers, and the heat-extensible fibers preferably has a larger contact angle than the second fiber.

From the viewpoint of expressing the hydrophilicity gradient between the upper layer 11 and the lower layer 12 and further increasing the ability to attract bodily fluids remaining on the skin-contacting surface of the upper layer 11 toward the lower layer 12 side, each fiber constituting the upper layer 11 is allowed to interact with water. It is preferable that all the contact angles are larger than the contact angle with water of the fibers forming the lower layer 12 . When the lower layer 12 is composed of a plurality of types of fibers, the contact angle with water of the fiber with the largest contact angle among the constituent fibers of the upper layer 11 is the same as that of the fiber with the largest content among the constituent fibers of the lower layer 12. The contact angle with water is preferably larger than the contact angle with water, and the contact angle with water of each fiber constituting the upper layer 11 is higher than the contact angle with water of the fiber having the highest content among the fibers constituting the lower layer 12. It is more preferable that the contact angle with water of each fiber constituting the upper layer 11 is larger than the contact angle with water of each fiber constituting the lower layer 12 .

When the upper layer 11 contains a second fiber different from the heat-extensible fiber in addition to the heat-extensible fiber, the second fiber contains, for example, two kinds of components having different melting points, and the fiber is not stretched by heating. Non-thermal extensible heat-fusible fibers can be used. Specifically, it contains, for example, a high melting point component and a low melting point component having a melting point lower than the melting point of the high melting point component, and the low melting point component exists continuously in at least a part of the fiber surface in the length direction. Composite fibers can be used. As the form of the heat-fusible conjugate fiber, there are various forms such as a core-sheath type and a side-by-side type. Concentric or eccentric core-sheath fibers are preferably used. Moreover, from the viewpoint of efficiently expressing the thermal fusion bondability of the second fibers, both the high-melting point component and the low-melting point component constituting the second fibers are preferably resin components.

When non-thermally extensible heat-fusible fibers are used as the second fibers, preferred combinations of the high melting point component and the low melting point component are as follows. Specifically, PP can be used as the high-melting component, and one or more of polyethylene such as HDPE, LDPE and LLDPE, ethylene-propylene copolymers, and polystyrene can be used as the low-melting component.
Another example of a suitable combination of a high melting point component and a low melting point component is to use polyester resins such as PET and PBT as the high melting point component, and polyethylene and ethylene such as HDPE, LDPE and LLDPE as the low melting point component. One or more of propylene copolymer, polystyrene, PP, copolyester, and the like can be used.
Still another example of a suitable combination of a high melting point component and a low melting point component is one or more of the above-described polyamide-based polymers and copolymers of two or more of the above high melting point components as the high melting point component. As the low-melting point component, one or more of two or more copolymers of the above low-melting point components can be used.
In addition to the above combinations, natural fibers such as cotton and pulp, and non-thermally extensible fibers such as rayon and acetate fibers that do not have heat-sealing properties may be further included.

Whether or not the upper layer 11 of the topsheet 10 contains thermally extensible fibers can be determined by measuring the thermal elongation rate of the fibers taken out from the topsheet 10 by the following method.
[Method for identifying thermally extensible fibers]
First, 10 fibers are collected from the surface sheet. The length of the fiber to be collected shall be 1 mm. The collected fibers are sandwiched between slides, and the total length of the sandwiched fibers is measured. A digital microscope VHX-6000 manufactured by KEYENCE is used for the measurement. Measurement was performed by observing the fiber at a magnification of 50 to 100 times and using a measurement tool incorporated in the apparatus for the observed image. The length obtained by the above measurement is defined as "total length of fibers collected from the surface sheet" F1. The fiber whose total length has been measured is placed in a sample container for DSC6200 manufactured by SII Nanotechnology Co., Ltd. (product name: robot container 52-023P, 15 μL, made of aluminum). The container containing the fiber is placed in a sample storage area in a heating furnace of DSC6200, which is previously set at a temperature 10° C. lower than the melting point or softening point of the low melting point component (second resin component) of the fiber. The temperature measured by the thermocouple installed directly under the sample storage area of the DSC6200 (display name in the measurement software: sample temperature) is ±1°C, which is 10°C higher than the melting point or softening point of the low-melting component (second resin component). After reaching the range of , heat for 60 seconds and then quickly remove. After the heat treatment, the fiber is taken out from the DSC sample container, sandwiched between slides, and the total length of the sandwiched fiber is measured. For the measurement, a microscope VHX-900 and a lens VH-Z20R manufactured by KEYENCE were used. Measurement was performed by observing the fiber at a magnification of 50 to 100 times and using a measurement tool incorporated in the apparatus for the observed image. The length obtained by the measurement is defined as "total length of fiber after heat treatment" F2. The thermal elongation rate (%) is calculated from the following formula. If the thermal elongation rate is greater than 0%, the fiber to be measured is determined to be a thermally extensible fiber, and if the thermal elongation rate is 0% or less, the fiber to be measured is not a thermally extensible fiber, i.e. Determined to be non-thermally extensible. A fiber having a thermal elongation rate of 0% or less is referred to as a second fiber in the present invention. The term "elongation rate of 0% or less" means that the total length of the fiber does not change before and after heating, or that the total length of the fiber is shortened by heating (heat shrinkability).
Fiber thermal elongation rate (%) = 100 × (F2 - F1) / F1
Further, when the upper layer 11 is determined to contain the second fibers in addition to the thermally extensible fibers by the method described above, the contact angle is measured independently for each fiber by the method described above.

In the surface sheet 10 , it is preferable that the average fiber diameter of the fibers having the smallest average fiber diameter among the fibers constituting the upper layer 11 is larger than the average fiber diameter of the fibers constituting the lower layer 12 . With such a structure, the fiber density of the lower layer 12 is higher than the fiber density of the upper layer 11, so that a strong capillary force is developed in the lower layer 12, and body fluid flows from the upper layer 11 to the lower layer 12. It becomes a thing excellent in entrainment property. As a result, the absorbed body fluid is efficiently transferred to the non-skin-contacting surface side, and the sheet has a good texture and makes it difficult to perceive residual fluid. One or two or more types of fibers can be used as the constituent fibers of the lower layer 12. When the lower layer 12 contains a plurality of types of fibers, the fiber diameter of the constituent fibers of the upper layer 11 is the same as that of the fibers constituting the lower layer 12. Compare with the fiber diameter of the fiber with the largest average fiber diameter.

Among the fibers constituting the upper layer 11, the average fiber diameter of the fiber having the smallest average fiber diameter is preferably 2.0 dtex or more, more preferably 2.5 dtex or more, when expressed in fiber fineness (decitex: dtex). , more preferably 3.0 dtex or more, preferably 8.0 dtex or less, more preferably 7.0 dtex or less, still more preferably 6.0 dtex or less. Similarly, the fiber diameter of the constituent fibers of the lower layer 12 is preferably 1.0 dtex or more, more preferably 1.2 dtex or more, still more preferably 1.5 dtex or more, and preferably 5.0 dtex or less, in terms of fineness. It is more preferably 4.0 dtex or less, still more preferably 3.0 dtex or less. When the lower layer 12 contains a plurality of types of fibers, the fibers having the largest average fiber diameter among the fibers constituting the lower layer 12 should be within the above range.

The fineness of fibers can be measured by the following method. That is, a measurement sample is prepared by cutting out a rectangular shape of 50 mm×100 mm (area of 5000 mm ² ) from the top sheet 10 to which no load is applied. Next, regarding the fineness of the fibers of the upper layer 11, a cross-sectional view of the measurement sample is taken, and 10 standard fibers located on the outer surface (skin contact surface) of the upper layer 11 of the measurement sample are examined with an electron microscope. The fiber thickness is actually measured using the fiber thickness, and the arithmetic mean value Dn (μm) of the fiber thickness is calculated. Next, using a differential scanning calorimeter (DSC), the standard fiber constituent resin was specified at a position spaced 10 mm from the skin contact surface, and the theoretical fiber density Pn (g/cm ³ ) was calculated. Ask. From the obtained arithmetic mean value Dn (μm) of the fiber thickness and the theoretical fiber density Pn (g/cm ³ ), the weight (g) per 10000 m of fiber length is calculated, and this calculated value is used as the upper layer 11 fiber fineness (dtex). With regard to the fineness of the fibers of the lower layer 12, a cross-sectional view of the measurement sample is taken, and 10 standard fibers located on the outer surface (non-skin contact surface) of the measurement sample are selected. Measured in the same manner as the fineness of

As shown in FIGS. 1 and 2, when the fixed portion 15 that joins the upper layer 11 and the lower layer 12 is formed, the fixed portion 15 is, as shown in FIG. It is preferable to form a macroscopic pattern consisting of rows of fixed portions in which linear first fixed portions 15a and second fixed portions 15b are alternately arranged along one direction.

Specifically, as shown in FIG. 2, the surface sheet 10 has linear first fixing portions 15a and linear second fixing portions 15b shorter in length than the first fixing portions 15a alternately. In addition, it has a plurality of first fixing portion rows L1 arranged so as to extend in one direction (from the upper left to the lower right on the paper surface of FIG. 2). A plurality of first fixing portion rows L1 are formed such that the intervals between adjacent first fixing portion rows L1 are different. The first fixing portion rows L1 are inclined with respect to the X direction in the drawing, and the first fixing portion rows L1 do not intersect with each other and are arranged parallel to each other. Similarly, in the second fixing portion row L2, a plurality of first fixing portions 15a and second fixing portions 15b are arranged so as to alternately extend in one direction (from the upper right to the lower left on the page of FIG. 2). . A plurality of second fixed portion rows L2 are formed such that the intervals between adjacent second fixed portion rows L2 are different. The second fixing portion rows L2 are inclined with respect to the X direction in the drawing, and the second fixing portion rows L2 do not intersect with each other and are arranged parallel to each other. Each second fixing portion row L2 is arranged to extend in a direction intersecting with each first fixing portion row L1. By arranging the first fixed portion row L1 and the second fixed portion row L2 in this way, body fluids are less likely to diffuse on the topsheet 10 in one direction, which is preferable.

Further, as shown in FIG. 2, the first fixing portion 15a and the second fixing portion 15b in the first fixing portion row L1 and the first fixing portion 15a and the second fixing portion 15b in the second fixing portion row L2 are are preferably arranged so as not to intersect with each other. Focusing on the first fixed portion row L1, a second fixed portion row L2 is formed between the first fixed portion 15a and the second fixed portion 15b that are adjacent to each other in the longitudinal direction in the extending direction of the first fixed portion row L1. The first fixing portion 15a and the second fixing portion 15b are arranged so as not to pass through. Focusing on the second fixed portion row L2, the first fixed portion row L1 is spaced between the first fixed portion 15a and the second fixed portion 15b that are adjacent to each other in the longitudinal direction in the extending direction of the second fixed portion row L2. are arranged so that neither the first fixing portion 15a nor the second fixing portion 15b that constitutes the

A region including the intersection of the first fixed portion row L1 and the second fixed portion row L2 is a non-joined area N1 that is not joined by the fixed

portions

15a and 15b. The non-bonded region N1 is composed of a first non-fixed region located between the first fixed portion 15a and the second fixed portion 15b that are adjacent to each other in the row direction in the first fixed portion row L1, and a second fixed portion row L2. , a second non-fixed region positioned between the first fixed portion 15a and the second fixed portion 15b that are adjacent to each other in the row direction. The non-bonding region N1 is formed between the first convex portion 18a and the third convex portion 18c that are adjacent to each other in the X direction and the Y direction orthogonal to the X direction. , 18b and 18c are continuous. Both the first fixing portion 15a and the second fixing portion 15b are concave portions 17, which are thinner than the convex portions 18 and the non-joining regions N1.

As described above, as shown in FIG. 2, by arranging the first fixed portion row L1 and the second fixed portion row L2 having two types of fixed

portions

15a and 15b to form the non-bonded region N1, Via the non-bonded regions N1 formed between the fixed portions 15, the body fluid can be efficiently diffused in the sheet plane direction and absorbed by the lower layer 12 side. more effectively reduced.

The content of the thermally extensible fibers in the upper layer 11 is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, of the total mass of the upper layer 11. is. The content of the second fibers is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, of the total mass of the upper layer 11. .

As the fibers that make up the lower layer 12, for example, non-thermally extensible heat-fusible fibers that contain two components with different melting points and that do not substantially elongate when heated can be used. The same fibers as the second fibers of the upper layer 11 can be used as the non-thermally extensible heat-fusible fibers. In addition, it may further contain natural fibers such as cotton and pulp, and non-thermally extensible fibers such as rayon and acetate fibers that do not have heat-sealing properties.

A preferred method for manufacturing the surface sheet 10 using this thermally extensible composite fiber will be described below with reference to FIG. FIG. 3 shows an embodiment of a manufacturing apparatus suitable for use in this manufacturing method. First, a predetermined web forming means (not shown) is used to fabricate a lower layer web 12A, which is the original fabric of the lower layer 12. As shown in FIG. The lower web 12</b>A is configured to contain no heat extensible fibers or a lower proportion of heat extensible fibers than the upper layer 11 . Separately from the lower web 12A, an upper web 11A, which is the raw fabric of the upper layer 11, is produced using a predetermined web forming means (not shown). The upper web 11A contains thermally extensible fibers. The web forming means is not particularly limited, and for example, a card method, an air lay method, or the like can be used.

Next, the upper web 11A and the lower web 12A are conveyed in one direction R and stacked to form a laminate 10A. The heat embossing device 21 includes an engraving roll 22 on the peripheral surface of which convex portions having a shape corresponding to the fixing portion 15 are formed, and a smooth roll 23 having a smooth peripheral surface. 23 can be heated to a predetermined temperature. By introducing the laminate 10A between the

rolls

22 and 23, the laminate 10A is integrally heat embossed. By heat embossing, the processed laminated body 10B is formed in which the fixed portion 15 is formed in which the upper layer web 11A and the lower layer web 12A are non-separably joined.

The heat embossing is preferably performed at a temperature at which the components constituting at least one of the upper web 11A and the lower web 12A are melted and the

webs

11A and 12A are heat-sealed. The processing temperature of the heat embossing is preferably higher than the melting point of the low-melting point component in the thermally extensible fibers in the upper web 11A and lower than the melting point of the high-melting point component.

Subsequently, the processed laminate 10B with the fixed portions 15 formed thereon is introduced into the hot air blowing device 25 . After being introduced into the hot air blowing device 25, the processed laminate 10B is subjected to air through processing by blowing hot air heated to a predetermined temperature. The air-through processing can be suitably performed at a temperature at which the thermally extensible fibers in the processed laminate 10B are elongated and at a temperature equal to or higher than the melting point of the low melting point component of the thermally extensible fiber and lower than the melting point of the high melting point component.

By subjecting the processed laminate 10B to an air-through process, the thermally extensible fibers contained in the upper layer 11 are stretched in portions other than the fixed portions 15. The stretched portion of the stretched thermally extensible fiber moves outward in the thickness direction of the processed laminate 10B, and a convex portion 18 is formed in the region surrounded by the fixed portions 15 in the upper layer 11 . In this way, the desired topsheet 10 made of nonwoven fabric is obtained.

It should be noted that the surface sheet 10 manufactured in this manner is still a thermally extensible fiber because the thermally extensible fibers thermally elongated by the air-through process can be thermally elongated. That is, the thermally extensible fibers present in the topsheet 10 are present in a thermally extensible state. In order to make the fibers thermally extensible even after the air-through processing, for example, the temperature of the hot air blown against the processed laminate 10B in the air-through processing is adjusted to the second resin component constituting the thermally extensible fibers in the processed laminate 10B. above the melting point or softening point of the second resin component +10°C or lower, and below the melting point or softening point of the first resin component. When the surface sheet 10 is manufactured, heat treatment under such conditions melts the second resin component having a low melting point and forms fusion points between the fibers. And the surface sheet 10 excellent in strength can be obtained. In addition, it is possible to prevent deterioration of the texture of the sheet and reduction of the strength of the sheet due to excessive melting of the thermally extensible fibers.

In the absorbent article of the present invention, as shown in FIG. 4, an intermediate sheet 30 made of non-woven fabric is arranged adjacent to the topsheet 10 between the topsheet 10 and the absorbent body 40 . FIG. 5(a) is a plan view of an intermediate sheet showing a preferred example of the intermediate sheet 30 preferably used in the absorbent article of the present invention.
The nonwoven fabric forming the intermediate sheet 30 has embossed portions 31 formed by embossing a fiber layer made of a nonwoven fabric or a fiber web. In the embossed portion 31, the fiber layer forming the intermediate sheet 30 is partially consolidated. In the intermediate sheet 30 , the embossed portion 31 is more compacted than the non-embossed portion 32 and has a smaller thickness than the non-embossed portion 32 .
As shown in FIG. 5(b), the embossed portion 31 of the intermediate sheet 30 may have concave portions 31b on both the skin-contacting surface and the non-skin-contacting surface. Only one of the surface on the contact surface side and the surface on the non-skin contact surface side may be the concave portion 31b.

As shown in FIG. 5( a ), in a plan view of the intermediate sheet 30 , it is preferable that a plurality of embossed portions 31 be separated from each other with a non-embossed portion 32 interposed therebetween. In the intermediate sheet 30 shown in FIG. 5(a), the embossed portions 31 include a plurality of mutually parallel first embossed portion rows R3 extending in one direction XY1 and mutually extending in the other direction XY2 intersecting the one direction. They are arranged so as to form a plurality of parallel second embossed portion rows R4.
In the intermediate sheet 30, the area ratio of the embossed portions 31 is larger than the area ratio of the fixed portions 15 of the surface sheet 10 described above. Since the fixed portions 15 of the topsheet 10 described above correspond to the embossed portions of the topsheet in the present invention, the fixed portions 15 of the topsheet 10 are hereinafter also referred to as embossed portions 15 of the topsheet 10 .

The area ratio of the embossed portions (embossing ratio) is the ratio of the total area of the embossed portions to the area of the entire sheet, and is measured as follows.
[Method for measuring area ratio of embossed part]
A rectangular sample having a length of 50 mm in the longitudinal direction and a length of 40 mm in the width direction of the absorbent article is cut out from the surface sheet or intermediate sheet to be measured.
Next, using a microscope (Keyence microscope VHX-900, lens VH-Z20R), a surface enlarged photograph of the cut sample was obtained, and the scale was adjusted to the surface enlarged photograph. , the dimension of the embossed portion is measured, and the embossed portion area U is calculated.
The area ratio (embossing ratio) of the embossed portion can be calculated by the formula (U/T)×100.
If the boundary between the embossed portion and other portions is unclear, it can be determined from an enlarged photograph of the surface sheet or intermediate sheet to be measured. Since the fibers of the embossed portion are crushed or in the form of a film, the embossed portion can be determined from an enlarged photograph of the sheet, and the boundary between the embossed portion and other portions can be ascertained.
In addition, when the absorbent article is a sanitary napkin, it is common to arrange compressed grooves extending from the surface sheet to the absorbent body as leak-proof grooves, but samples are cut from places where leak-proof grooves are not arranged. . In addition, if there are embosses from the surface sheet to the intermediate sheet or the absorbent body other than the leak-proof grooves and it is not possible to cut out the sample so as not to include the emboss, cut the sample so as to include the emboss, The area ratio may be measured. The embossing from the surface sheet to the absorber other than the leak-proof grooves includes, for example, pin embossing formed over the entire area of the surface sheet in plan view.

In the present invention, as the intermediate sheet 30, the contact angle of the fibers forming the intermediate sheet 30 with water is larger than that of the fibers forming the topsheet 10 with water.
The contact angle with water of the fibers constituting each of the top sheet and the intermediate sheet was determined by measuring five fibers from the skin-contacting surface of the top sheet in the same manner as the contact angle measurement method described above. Measurement sample, 5 measurement samples are taken from the fibers located on the non-skin contact surface of the intermediate sheet and located in the non-embossed portion 32, and the contact angles of these 10 measurement samples (N = 10) are measured below the decimal point. The contact angle with water of the fibers constituting the surface sheet or the intermediate sheet is obtained by measuring to one digit and arithmetically averaging the measured values of 10 points (rounded to the second decimal place).

When the fibers forming the intermediate sheet 30 each include a plurality of types of fibers having different contact angles, the intermediate sheet 30 contacts water more than the fibers forming the lower layer 12 of the top sheet. It preferably contains at least 50%, more preferably 80% or more, of high-angle fibers. Among the fibers constituting the intermediate sheet 30, the content of the fibers having a larger contact angle with water than the fibers constituting the lower layer 12 of the top sheet is determined by the above-described [Fibers constituting the upper layer, the fibers constituting the lower layer method for measuring the content of fibers having a larger contact angle with water than the upper layer 11, except that the fibers are taken out from the intermediate sheet 30 instead of the upper layer 11, and the measurement can be performed in the same manner. In addition, when the lower layer 12 contains a plurality of types of fibers, the intermediate sheet 30 contains at least 50% of fibers having a larger contact angle with water than the fibers with the highest content among the fibers constituting the lower layer 12. It is preferably contained, more preferably 80% or more. Further, the contact angle of the fibers forming the intermediate sheet 30 is preferably 97° or less, more preferably 90° or less, and preferably 75° or more, more preferably 78° or more.

The difference in contact angle with water between the fibers forming the intermediate sheet 30 and the fibers forming the top sheet 10 is preferably 2° or more, more preferably 5° or more, in terms of the difference between the former and the latter. 15° or less is preferable, and 10° or less is more preferable. This preferable range of contact angle difference is also applied to the relationship between the upper layer 11 of the surface sheet 10 and the intermediate sheet 30 .

According to the absorbent article of the present invention, the hydrophilicity of the fibers forming the lower layer 12 of the topsheet is higher than the hydrophilicity of the fibers forming the upper layer 11, so that body fluid excreted on the upper layer 11 side is hydrophilic. becomes easier to migrate to the lower layer 12 side where the In addition, the intermediate sheet 30 has a larger area ratio of the embossed portions than the topsheet 10 and a larger contact angle with water than the lower layer of the topsheet 10 . The speed at which the liquid passes through the sheet 30 is increased, and even when the amount of excretion is large or the excretion speed is high, the liquid moves quickly from the top sheet to the absorbent body, and the surface of the top sheet becomes sticky. Pleasure can be prevented more reliably. The reason for this is that when the area ratio of the embossed portions of the intermediate sheet is high, the ability to draw the liquid from the surface sheet to the embossed portions of the intermediate sheet or the vicinity thereof increases, while the liquid tends to remain in other portions. When the contact angle of the fibers constituting the intermediate sheet is increased to increase the degree of water repellency, it becomes difficult for the liquid to be retained in that portion, and the liquid smoothly transfers to the absorbent body 40 through the embossed portion and its vicinity. presumed to be. The structure of the present invention should be present at least in the excretory part facing region (or the crotch part), preferably in the rear part in addition to this, and more preferably in the front part.

From the viewpoint of achieving such an effect more reliably, the water contact angle of the fibers forming the intermediate sheet 30 should be larger than the water contact angle of the fibers forming the upper layer of the top sheet 10 . is preferred.

In addition, the fact that the contact angle with water increases in the order of the fibers forming the lower layer of the top sheet, the fibers forming the upper layer of the top sheet, and the fibers forming the intermediate sheet means that liquid migration from the top sheet is excellent. is preferable from the viewpoint of improvement of Since the fibers forming the intermediate sheet have a larger contact angle with water than the fibers forming the lower layer of the top sheet, it can be expected that liquid that has migrated to the absorbent body will be prevented from returning.

From the viewpoint of improving the transferability of the liquid from the surface sheet 10, the area ratio (%) of the embossed portion of the intermediate sheet 30 is preferably 15% or more, more preferably 20% or more, and preferably 40% or less. , more preferably 35% or less, preferably 15% or more and 40% or less, and more preferably 20% or more and 35% or less.
From the same point of view, the difference between the area ratio of the embossed portions of the intermediate sheet 30 and the area ratio of the embossed portions of the topsheet 10 is preferably 2% points or more, more preferably 5% points or more, and preferably It is 40% points or less, more preferably 35% points or less, preferably 2% points or more and 40% points or less, more preferably 5% points or more and 35% points or less.
On the other hand, from the viewpoint of surface liquid residue on the surface sheet 10 and touch feeling, the area ratio (%) of the embossed portion of the surface sheet 10 is preferably 5% or more, more preferably 7% or more, and preferably 13% or less. , more preferably 11% or less, preferably 5% or more and 13% or less, more preferably 7% or more and 11% or less.

The surface sheet 10 in the present invention is not limited to having a fixed portion (embossed portion) that connects the upper layer and the lower layer to each other, but the surface sheet 10 may have a fixed portion (embossed portion) that connects the upper layer and the lower layer to each other. embossed portions), and the intermediate sheet 30 preferably has a larger area ratio of the embossed portions than the surface sheet 10 . With such a structure, it is difficult for the liquid to remain on the surface sheet 10, and in addition, it is possible to effectively prevent stuffiness and rashes.

As the fibers that make up the intermediate sheet 30, for example, non-thermally extensible heat-fusible fibers that contain two components with different melting points and that do not substantially elongate when heated can be used. The same fibers as the second fibers of the upper layer 11 can be used as the non-thermally extensible heat-fusible fibers. In addition, it may further contain natural fibers such as cotton and pulp, and non-thermally extensible fibers such as rayon and acetate fibers that do not have heat-sealing properties.

The basis weight of the intermediate sheet 30 is preferably 15 g/m ² or more, more preferably 15 g/m 2 or more, from the viewpoint of improving the transferability of the liquid from the top sheet 10 to the absorbent body 40 and from the viewpoint of preventing the liquid from flowing back from the absorbent body 40 . 17.5 g/m ² or more, preferably 40 g/m ² or less, more preferably 37.5 g/m ² or less, more preferably 15 g/m ² or more and 40 g/m ² or less, and still more preferably 17.5 g/m 2 or more. It is 5 g/m ² or more and 37.5 g/m ² or less.
The basis weight of the intermediate sheet 30 may be larger or smaller than the basis weight of the topsheet 10 , but is preferably approximately the same as the basis weight of the topsheet 10 .

In the present invention, it is not essential that the surface sheet 10 and the intermediate sheet 30 are joined together. However, it is preferable that the top sheet 10 and the intermediate sheet 30 are joined together by pressing portions 35 where the top sheet 10 and the intermediate sheet 30 are integrally pressed as shown in FIG. 4, for example. Alternatively or additionally, it is also preferable that the top sheet 10 and the intermediate sheet 30 are bonded together with an adhesive. By bonding between the top sheet 10 and the intermediate sheet 30, the transferability of the liquid from the top sheet 10 to the intermediate sheet 30 is further improved.

In the absorbent article of the present invention, the constituent fibers of the topsheet 10 and the intermediate sheet 30 preferably contain an inorganic filler. Examples of inorganic fillers include titanium oxide such as titanium dioxide, silica, and calcium carbonate. In the present invention, one of these inorganic fillers may be used alone, or two or more thereof may be used in combination. Among these inorganic fillers, titanium oxide, particularly titanium dioxide, is preferred from the standpoint of concealability of the nonwoven fabric.
The content of the inorganic filler contained in the constituent fibers of the surface sheet 10 or the intermediate sheet 30 is preferably 0.5% by mass or more in the constituent fibers from the viewpoint of improving the concealability of the color of the absorbed liquid such as menstrual blood. , more preferably 1.0% by mass or more. On the other hand, the content of the inorganic filler in the constituent fibers of each of the surface sheet and the intermediate sheet 30 is preferably 10% by mass or less, more preferably 9.0% by mass or less, and preferably 0.5% by mass or more and 10% by mass. % by mass or less, more preferably 1.0% by mass or more and 9.0% by mass or less.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments.
For example, the planar shape of each embossed portion of the intermediate sheet 30 may be rectangular instead of square, or may be any other shape such as circular, triangular, or elliptical. Further, the embossed portions are not limited to a plurality of individually independent embossed portions, and may be embossed portions or the like that are continuous in a grid pattern.

Experimental example

The present invention will be described in more detail below with experimental examples. However, the scope of the invention is not limited to such examples.

[Experimental example 1]
Using the manufacturing apparatus shown in FIG. 3, heat-extensible fibers (core resin: PP (melting point: 164° C.)/sheath resin: HDPE (melting point: 126° C.)) and heat-fusible fibers (core resin: The upper layer 11 (basis weight: 12.5 g/m ² ) consisting only of two types of fibers: PET (melting point: 251°C)/sheath resin: HDPE (melting point: 126°C), and heat-fusible fibers (core resin: PET (melting point 251° C.)/sheath resin: HDPE ⁽ melting point 126° C.)). The content of the thermally extensible fibers in the upper layer 11 was 50% by mass of the total mass of the upper layer 11 , and the content of the heat-fusible fibers was 50% by mass of the total mass of the upper layer 11 .
2 is formed on the surface sheet 10 by heat embossing. The length of the fixed portion 15b is 5.6 mm, and the first fixed portion 15a and the second fixed portion 15b in one fixed portion row are arranged so that the interval is 2.0 mm. Table 1 shows the contact angle and fineness of the constituent fibers of both

layers

11 and 12, and the area ratio of the fixed portions (embossed portions) of the topsheet 10 produced.
Table 1 shows the content (%) of the inorganic filler (titanium oxide) in the constituent fibers of the surface sheet. The basis weight of the top sheet 10 produced was 25 g/m ² .

As the intermediate sheet, a nonwoven fabric made of 100% by mass of heat-fusible fibers (core resin: PET (melting point: 251°C)/sheath resin: HDPE (melting point: 126°C)) was heat embossed, as shown in FIG. The one provided with the embossed portion 31 in a pattern was used. The contact angle and average fiber diameter of the intermediate sheet 30 are also shown in Table 1. For both the first embossed portion row R3 and the second embossed portion row R4, the length L3 of the embossed portions along the row was set to 0.77 mm, and the arrangement pitch L4 of the embossed portions along the row was set to 1.4 mm. Table 1 shows the contact angle and average fiber diameter of the constituent fibers of the produced intermediate sheet 30 and the area ratio of the embossed portion of the produced intermediate sheet 30 .
Table 1 shows the content (%) of the inorganic filler (titanium oxide) in the constituent fibers of the intermediate sheet. The basis weight of the produced intermediate sheet 30 was 25 g/m ² .
An absorbent article (sanitary napkin) having the obtained topsheet 10 and intermediate sheet 30 was manufactured. The configuration of the absorbent article other than the topsheet 10 and the intermediate sheet 30 adjacent thereto was the same as that of a sanitary napkin (Laurier Slimguard (registered trademark) with extra feathers for daytime use) manufactured by Kao Corporation.

[Experimental example 2]
An intermediate sheet having embossed portions in the same pattern as in Experimental Example 1 was obtained in the same manner as in Experimental Example 1, except that the amount of the inorganic filler was changed. A sanitary napkin was produced in the same manner as in Experimental Example 1, except that this intermediate sheet was used. The contact angle and average fiber diameter of the intermediate sheet 30 are also shown in Table 1.
[Experimental example 3]
A sanitary napkin manufactured by Kao Corporation (Laurier Slim Guard (registered trademark) with especially large number of wings for daytime use) was used as Experimental Example 3.

[Evaluation of liquid passage time]
The liquid penetration time of the sanitary napkins produced in Experimental Examples 1 and 2 and the sanitary napkin of Experimental Example 3 was examined. This liquid passage time is an index indicating that the shorter the liquid passage time, the better the liquid permeability of the sanitary napkin and the less liquid remains on the surface sheet. For measuring the liquid passage time, a tester LISTER manufactured by Lenzing Technik was used, and the sanitary napkins of Experimental Examples 1, 2 and 3 were placed on the measurement part of this tester and tested The liquid permeation time was investigated when 5 g of a solution (simulated blood) was injected. As the test solution, a solution adjusted as follows was used. 1,500 g of ion-exchanged water was placed in a 2 L beaker, and 5.3 g of sodium carboxymethylcellulose (CMC-Na manufactured by Kanto Kagaku Co., Ltd.) was added while stirring with a magnetic stirrer (this solution is referred to as "A"). Next, put 556 g of ion-exchanged water in a 1 L beaker, add 27.0 g of sodium chloride (manufactured by Kanto Kagaku Co., Ltd.) and 12 g of sodium bicarbonate (NaHCO ₃ , manufactured by Kanto Kagaku Co., Ltd.) while stirring with a stirrer. (this solution is referred to as "B"). Further, 900 g of glycerin was weighed into a 3 L beaker, and the above (A) and (B) were added and stirred. Furthermore, nonionic surfactant "Emulgen 935" [manufactured and sold by Kao Corporation] concentration (surfactant / water) = 15 ml of aqueous solution of 1 g / L, food red No. 2 [sold by Eisen Co., Ltd., Hodogaya Chemical Industry Co., Ltd., Manufacturer: Daiwa Kasei Co., Ltd.] 0.3 g was added and stirred. The solution thus obtained was subjected to suction filtration using a glass filter, and the filtrate was used as simulated blood. When preparing the simulated blood, other nonionic surfactants can be used in place of the surfactants described above, and similar results can be obtained in this case as well.
Table 1 shows the liquid passing time.

[Evaluation of hiding property (red board hiding rate)]
A sheet obtained by laminating the surface sheet and the intermediate sheet produced in Experimental Examples 1 and 2 was prepared and used as a sample for evaluation of hiding property. The hiding property is indicated by the value of the red plate hiding rate shown below. The red plate hiding rate is obtained as follows using a color difference meter (product number SZ-Σ80) manufactured by Nippon Denshoku Co., Ltd.
First, measure the spectral curve of the attached red plate (the red surface is the measurement surface). Among the obtained absorption wavelengths, 500 cm ⁻¹ is particularly selected, and the reflectance at this time is recorded (Ra). Next, the red plate is removed, the sample is placed on the sample table, and the red plate is placed so that the back surface of the sample (surface opposite to the measurement surface) faces the red surface of the red plate. The measurements are made five times in total for one sample at different sites, and the average value (Rb) of the reflectance at 500 cm ⁻¹ is calculated. From the obtained values of Ra and Rb, the red plate hiding rate is obtained by the following equation (1).
Red plate hiding rate (%) = [(Rb-Ra) / (100-Ra)] × 100
Table 1 shows the red plate hiding rate.

As shown in Table 1, the sanitary napkin of Experimental Example 1 has a higher liquid permeability than the sanitary napkin of Experimental Example 2 because the contact angle of the intermediate sheet is higher than that of the top sheet. Further, since the content of the inorganic filler in the intermediate sheet is higher in Experimental Example 1 than in Experimental Example 2, the red plate hiding rate is improved.
In other words, from a comparison of the results of Experimental Examples 1 and 2, by making the contact angle of the constituent fibers of the intermediate sheet larger than that of the surface sheet, the liquid permeability can be improved, and the contact angle of the constituent fibers of the intermediate sheet can be improved. It can be seen that the red plate hiding rate can be improved by making the content of the inorganic filler larger than that of the surface sheet.
Moreover, from the comparison of the results of Experimental Examples 1 and 3, it is found that the liquid permeability can be further improved by making the area ratio of the embossed portions of the intermediate sheet larger than that of the surface sheet.

According to the absorbent article of the present invention, it is possible to quickly transfer the liquid from the topsheet to the absorbent body, making it difficult for the liquid to remain on the topsheet.

Claims

It has a liquid-permeable topsheet, a backsheet, and an absorbent body positioned between the topsheet and the backsheet, and has a longitudinal direction corresponding to the front-rear direction of the wearer and a width direction orthogonal to the longitudinal direction. An absorbent article,
The surface sheet comprises an upper layer arranged on the skin-contacting side and a lower layer arranged on the non-skin-contacting side,
The upper layer includes a plurality of types of fibers having different contact angles with water,
The contact angle with water of the fibers constituting the upper layer is larger than the contact angle with water of the fibers constituting the lower layer,
An intermediate sheet made of nonwoven fabric is arranged adjacent to the surface sheet between the surface sheet and the absorbent body,
The intermediate sheet has embossed portions, and the intermediate sheet has a larger area ratio of the embossed portions, which is the ratio of the total area of the embossed portions to the area of the sheet, than the surface sheet,
The absorbent article, wherein the contact angle of the fibers forming the intermediate sheet with water is larger than the contact angle of the fibers forming the top sheet with water.
The upper layer is a fiber assembly containing thermally extensible fibers,
2. The absorbent article according to claim 1, wherein the lower layer is a fiber assembly that does not contain thermally extensible fibers or contains thermally extensible fibers in a lower mass proportion than the upper layer.
The upper layer contains heat-extensible fibers and non-thermally-extensible heat-fusible fibers as a plurality of types of fibers having mutually different contact angles with water,
The absorbent article according to claim 1 or 2, wherein the thermally extensible fibers have a larger contact angle than the non-thermally extensible thermally adhesive fibers.
The absorbent article according to any one of claims 1 to 3, wherein each of the fibers forming the upper layer has a larger contact angle with water than the contact angle with water of the fibers forming the lower layer.
The absorbent according to any one of claims 1 to 4, wherein the water contact angle of the fibers constituting the intermediate sheet is larger than the water contact angle of the fibers constituting the upper layer of the top sheet. Goods.
6. The method according to any one of claims 1 to 5, wherein the contact angle with water increases in the order of the fibers forming the lower layer of the top sheet, the fibers forming the upper layer of the top sheet, and the fibers forming the intermediate sheet. An absorbent article according to any one of the preceding claims.
Claims 1 to 6, wherein the surface sheet has embossed portions that connect the upper layer and the lower layer, and the intermediate sheet has a larger area ratio of the embossed portions than the surface sheet. Absorbent article according to any one of.
8. The composition according to any one of claims 1 to 7, wherein the constituent fibers of the surface sheet and the constituent fibers of the intermediate sheet each contain 0.5% by mass or more and 10% by mass or less of an inorganic filler in the fibers. absorbent article.
The absorbent according to any one of claims 1 to 8, wherein the surface sheet and the intermediate sheet are joined to each other by a pressed portion where the surface sheet and the intermediate sheet are pressed integrally or by an adhesive. sexual goods.
The surface sheet has an embossed portion that joins the upper layer and the lower layer, a convex portion is formed in a region surrounded by the embossed portion, and the embossed portion forms a concave portion. Item 10. The absorbent article according to any one of Items 1 to 9.
The surface sheet has an embossed portion that connects the upper layer and the lower layer to each other,
The embossed portions constitute a first fixed portion row and a second fixed portion row that are inclined in opposite directions with respect to one direction,
A large number of the first fixed portion row and the second fixed portion row are formed parallel to each other,
11. A plurality of first fixing portion rows and second fixing portion rows each alternately having locations where the spacing between adjacent fastening portion rows is wide and locations where the spacing is narrow. The absorbent article according to claim 1.
The absorbent article according to claim 11, wherein the embossed portions forming the first fixed portion row and the second fixed portion row are discontinuous lines.
According to claim 11 or 12, in the region surrounded by the first fixing portion row and the second fixing portion row, three types of protrusions having different areas are formed so as to protrude toward the skin contact surface side. The absorbent article described.
The absorbent article according to claim 13, wherein the three types of protrusions with different areas have different heights.
The embossed portion of the surface sheet has a linear first fixed portion and a linear second fixed portion shorter in length than the first fixed portion,
The first fixing portion row and the second fixing portion row are respectively formed by arranging the first fixing portions and the second fixing portions alternately and extending in one direction,
Claim 11, wherein the first fixing portions and the second fixing portions in the first fixing portion row and the first fixing portions and the second fixing portions in the second fixing portion row are arranged so as not to cross each other. 15. The absorbent article according to any one of -14.
16. The area including the intersection of the first fixed portion row and the second fixed portion row is a non-bonded area that is not bonded by the embossed portion of the surface sheet. Absorbent article according to.
The absorbent article according to any one of claims 1 to 16, wherein the area ratio of the embossed portion of the intermediate sheet is 15% or more and 40% or less.
the surface sheet has an embossed portion connecting the upper layer and the lower layer to each other;
The absorbent article according to any one of claims 1 to 17, wherein a difference between the area ratio of the embossed portions of the intermediate sheet and the area ratio of the embossed portions of the top sheet is 2% points or more.
the surface sheet has an embossed portion connecting the upper layer and the lower layer to each other;
The absorption according to any one of claims 1 to 18, wherein the difference between the area ratio of the embossed portion of the intermediate sheet and the area ratio of the embossed portion of the top sheet is 2% points or more and 40% points or less. sexual goods.
the surface sheet has an embossed portion connecting the upper layer and the lower layer to each other;
The absorbent article according to any one of claims 1 to 19, wherein the area ratio of the embossed portions of the topsheet is 5% or more and 13% or less.
The absorbent article according to any one of claims 1 to 20, wherein the upper layer contains at least 50% of fibers having a larger contact angle with water than the fibers constituting the lower layer.