CN110325679B

CN110325679B - Absorbent article

Info

Publication number: CN110325679B
Application number: CN201780087145.1A
Authority: CN
Inventors: 福田优子; 小林秀行; 凑崎真行; 奥田泰之
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2017-03-15
Filing date: 2017-03-15
Publication date: 2022-04-12
Anticipated expiration: 2037-03-15
Also published as: RU2723405C1; JPWO2018167882A1; CN110325679A; JP6539007B2; WO2018167882A1

Abstract

The present invention provides a laminated nonwoven fabric (10) having a laminated structure (13) of fiber layers containing thermoplastic fibers. The laminated structure (13) has a first surface (10a) which is one surface of the laminated nonwoven fabric (10) and a second surface (10b) which is the other surface, the first surface (10a) is composed of a hydrophilic first layer (11), and a hydrophobic second layer (12) is arranged on the second surface (10b) side of the first layer (11). The laminated structure (13) has an interlayer weld (16) that has a thickness smaller than the peripheral portion and that mutually welds the layers that constitute the laminated structure (13). The first layer (11) has inter-fiber fusion sections (17) that have a thickness smaller than the peripheral section and in which the constituent fibers of the first layer (11) are fused to each other, in addition to the interlayer fusion sections (16). The first surface (10a) has a greater weld area ratio than the second surface (10 a). The laminated nonwoven fabric (10) having such a structure is excellent in the absorption performance of body fluids such as sweat and urine.

Description

Absorbent article

Technical Field

The present invention relates to an absorbent article using a laminated nonwoven fabric having a laminated structure in which a plurality of nonwoven fabrics are laminated.

Background

In absorbent articles such as disposable diapers and sanitary napkins, nonwoven fabrics having a laminate structure of 2 or more layers, nonwoven fabrics having irregularities on the surface, and the like have been used as components. For example, patent document 1 describes a technique of disposing a sweat-absorbing sheet capable of absorbing sweat of a wearer at a portion of a disposable diaper which is in contact with the skin of the wearer, and a technique of using a laminated nonwoven fabric having a laminated structure of a hydrophobic nonwoven fabric and a hydrophilic nonwoven fabric as the sweat-absorbing sheet, and joining the two nonwoven fabrics to each other by a plurality of heat-fusion portions recessed in a concave shape, and further a technique of disposing the laminated nonwoven fabric so that the hydrophobic nonwoven fabric faces the skin of the wearer.

Patent document 2 describes a single-direction water-conductive nonwoven fabric sheet having liquid permeability from one surface direction and no liquid permeability from the opposite direction as a laminated nonwoven fabric suitable as a component of an absorbent article, and describes an embodiment of the single-direction water-conductive nonwoven fabric sheet in which at least 1 layer is a hydrophilized nonwoven fabric and the remaining layers are non-hydrophilized nonwoven fabrics. Patent document 2 describes a method of laminating a plurality of nonwoven fabrics and performing a thermal fusion treatment by a heat embossing roll as a method of manufacturing a laminated nonwoven fabric, and further describes a method of directly depositing long fibers having a predetermined fineness on a spunbonded nonwoven fabric and then performing a cross-knitting treatment by a means such as needle punching, water jet, ultrasonic sealing, or a thermal fusion treatment by a heat embossing roll as another manufacturing method.

Patent document 3 describes a laminated nonwoven fabric in which an inner layer made of a hydrophobic ultrafine fiber nonwoven fabric and an outer layer made of a synthetic fiber nonwoven fabric to which a hydrophilic agent is attached are partially bonded together by an adhesive or hot embossing as a functional filter for extracting coffee or black tea.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2004-298467

Patent document 2: japanese patent laid-open publication No. 2006-51649

Patent document 3: japanese patent laid-open publication No. 2002-233720

Disclosure of Invention

The present invention aims to provide a laminated nonwoven fabric having a laminated structure of fiber layers containing thermoplastic fibers. The laminated structure has a first surface as one surface of the laminated nonwoven fabric and a second surface as the other surface, the first surface is composed of a hydrophilic first layer, and a hydrophobic second layer is disposed on the second surface side of the first layer. The laminated structure has an interlayer welded portion having a thickness smaller than that of the peripheral portion and in which the layers constituting the laminated structure are welded to each other. The first layer has inter-fiber fusion parts, which have a thickness smaller than that of the peripheral part and in which the constituent fibers of the first layer are fused to each other, in addition to the interlayer fusion parts. When the ratio of the total area of the interlayer fusion and the interfiber fusion in the first surface to the area of the second surface is referred to as the fusion area ratio of each surface, the fusion area ratio of the first surface is larger than the fusion area ratio of the second surface.

The present invention also provides a method for producing a laminated nonwoven fabric having a laminated structure of fiber layers containing thermoplastic fibers, wherein the layers constituting the laminated structure are fused to each other by interlayer fusion. The method for producing a laminated nonwoven fabric of the present invention comprises: a step of obtaining a laminate by conveying a hydrophilic base nonwoven fabric having a thickness smaller than the peripheral portion and constituting an interfiber fusion portion in which fibers are fused to each other, and depositing hydrophobic fibers obtained by spinning a resin on the base nonwoven fabric being conveyed to obtain a laminate; and an interlayer welding step of locally compressing and heating the laminate in the thickness direction to form the interlayer weld.

The present invention also provides an absorbent article having a laminated nonwoven fabric having a laminated structure of fiber layers containing thermoplastic fibers. The laminated structure has a first surface as one surface of the laminated nonwoven fabric and a second surface as the other surface, the first surface being composed of a hydrophilic first layer, and a hydrophobic second layer being disposed on the second surface side of the first layer. The laminated structure has an interlayer weld portion having a thickness smaller than the peripheral portion and in which the layers constituting the laminated structure are welded to each other. The first layer has inter-fiber fusion parts, which have a thickness smaller than the peripheral part and are formed by fusing the constituent fibers of the first layer to each other, in addition to the interlayer fusion parts. When the ratio of the total area of the interlayer fusion and the interfiber fusion in the first surface to the area of the second surface is referred to as the fusion area ratio of the respective surfaces, the fusion area ratio of the first surface is larger than the fusion area ratio of the second surface. The laminated nonwoven fabric is disposed such that the second surface faces the skin of the wearer.

The present invention also provides a sweat-absorbent sheet having a layered structure of fiber layers containing thermoplastic fibers, and having a first surface and a second surface on the opposite side thereof, the second surface being used so as to face the skin of a wearer. The first surface is composed of a hydrophilic first layer, and a hydrophobic second layer is disposed on the second surface side of the first layer. The laminated structure has an interlayer welded portion having a thickness smaller than that of the peripheral portion and in which the layers constituting the laminated structure are welded to each other. The first layer has an inter-fiber fusion part having a thickness smaller than the peripheral part and in which the constituent fibers of the first layer are fused to each other, in addition to the interlayer fusion part. When the ratio of the total area of the interlayer fusion and the interfiber fusion in the first surface to the area of the second surface is referred to as the fusion area ratio of the respective surfaces, the fusion area ratio of the first surface is larger than the fusion area ratio of the second surface.

Drawings

Fig. 1 is a cross-sectional view schematically showing a cross section along the thickness direction of one embodiment of the laminated nonwoven fabric of the present invention.

Fig. 2 (a) to 2 (d) are each a schematic view showing the pattern of the interlayer fusion joint of the present invention.

Fig. 3 (a) to 3 (h) are schematic views each showing the pattern of the fiber-to-fiber fusion part of the present invention.

Fig. 4 (a) to 4 (d) are schematic views each showing the pattern of the welded portions (interlayer welded portions and fiber welded portions) on the first surface of the laminated nonwoven fabric of the present invention.

Fig. 5 is a schematic view of an embodiment of the method for producing a laminated nonwoven fabric of the present invention.

Fig. 6 is a schematic perspective view of a pants-type disposable diaper according to an embodiment of the absorbent article of the present invention.

Fig. 7 is an expanded perspective view schematically showing the skin contact surface side (inner surface side) in an expanded and stretched state of the diaper shown in fig. 6.

Fig. 8 is a longitudinal sectional view schematically showing a section taken along line I-I of fig. 7.

Detailed Description

As described in patent documents 1 to 3, it is difficult to reduce the grammage of each layer constituting a laminated structure of a laminated nonwoven fabric obtained by integrating a plurality of nonwoven fabrics by a hot-embossing process, and particularly difficult to reduce the grammage of a hydrophobic layer. Therefore, such a laminated nonwoven fabric has a high basis weight and high rigidity as a whole, and when used as a component of an absorbent article, there is a possibility that the wearing sensation may be reduced, and when the hydrophobic layer is disposed at a position closest to the skin of the wearer, the absorbency of bodily fluids such as sweat and urine may be deteriorated.

As a method for producing a laminated nonwoven fabric, there is known a method in which fibers are sequentially suspended from a plurality of spinning heads intermittently arranged in a Machine Direction (MD) and stacked, and the stacked fibers are subjected to hot embossing on the downstream side of the spinning head located on the most downstream side in the MD to be integrated. Since the laminated nonwoven fabric formed by such so-called direct spinning has a relatively low grammage and low stiffness, when the hydrophobic layer is disposed at a position closest to the skin of the wearer, the body fluid can be absorbed from around the embossed portion of the hydrophobic layer, but since the constituent fibers of the hydrophilic layer adjacent to the hydrophobic layer are densely present around the embossed portion and the thickness of the hydrophobic layer is relatively thin, the body fluid is likely to concentrate around the embossed portion, and the liquid is likely to flow back.

Accordingly, an object of the present invention is to provide a laminated nonwoven fabric having excellent absorption performance for body liquids such as sweat and urine, a method for producing the same, an absorbent article, and a sweat-absorbing sheet.

The present invention will be described based on preferred embodiments thereof with reference to the accompanying drawings. Fig. 1 is a cross section along the thickness direction Z of a laminated nonwoven fabric 10 schematically showing an embodiment of the laminated nonwoven fabric of the present invention. The laminated nonwoven fabric 10 has a laminated structure 13 including fiber layers of thermoplastic fibers, which typically constitute layers of a single-layer nonwoven fabric (e.g., spunbond nonwoven fabric) or a laminated nonwoven fabric (e.g., SMS nonwoven fabric), which is a nonwoven fabric. The laminated structure 13 has a first surface 10a which is one surface (outer surface) of the laminated nonwoven fabric 10, and a second surface 10b which is the other surface (outer surface) of the laminated nonwoven fabric 10 and is located on the opposite side of the first surface 10 a.

One of the main features of the laminated nonwoven fabric 10 is that the laminated structure 13 has a gradient in hydrophilicity in the thickness direction Z. That is, in the laminated structure 13, the first surface 10a is constituted by the hydrophilic first layer 11 containing the hydrophilic fibers 14, and the hydrophobic second layer 12 containing the hydrophobic fibers 15 is disposed on the second surface 10b side of the first layer 11, and by this structure, a hydrophilicity gradient such as "the hydrophilicity is relatively high on the first surface 10a side compared with the hydrophilicity on the second surface 10b side" is given to the laminated structure 13, and a hydrophilicity gradient such as "the hydrophilicity is relatively low on the first surface 10a side and the hydrophilicity is relatively high on the second surface 10b side" is given to the hydrophilic first layer 11.

In the laminated nonwoven fabric 10 shown in fig. 1, the laminated structure 13 is a 2-layer structure of a hydrophilic first layer 11 and a hydrophobic second layer 12, the first surface 10a is formed of the first layer 11 and is hydrophilic, and the second surface 10b is formed of the second layer 12 and is hydrophobic. Here, the "number of layers of the laminated structure 13 is 2" merely means the total number of layers of two layers (the first layer 11 and the second layer 12) having different forms or functions, and does not necessarily coincide with the number of layers of the fiber layer (nonwoven fabric) in a strict sense. That is, as described later, the first layer 11 and the second layer 12 may be not only a nonwoven fabric having a single-layer structure but also a nonwoven fabric having a multilayer structure of 2 or more layers (for example, SMS nonwoven fabric), and for example, in the case where the first layer 11 is an SMS nonwoven fabric and the second layer 12 is a nonwoven fabric having a single-layer structure, even if the first layer 11 and the second layer 12 have a 2-layer structure, the number of actual nonwoven fabrics is 4 in total, that is, 3 in the first layer 11 and 1 in the second layer 12. In short, each of the first layer 11 and the second layer 12 may have 2 or more layers.

In the present invention, the hydrophilicity of the fiber layer (nonwoven fabric) which is an aggregate of fibers is determined based on the contact angle with water measured by the following method, and the hydrophilicity is determined if the contact angle is less than 90 degrees, and the hydrophobicity is determined if the contact angle is 90 degrees or more. The smaller the contact angle with water measured by the method described below, the higher the hydrophilicity (the lower the hydrophobicity), and the larger the contact angle, the lower the hydrophilicity (the higher the hydrophobicity). In the laminated structure 13 of the laminated nonwoven fabric 10, the contact angle of the hydrophilic first layer 11 measured by the following method is less than 90 degrees, and the contact angle of the hydrophobic second layer 12 measured by the following method is 90 degrees or more.

< method for measuring contact angle of fiber layer (nonwoven fabric) >

A rectangular shape in plan view having a MD direction of 150mm and a CD direction of 70mm was cut out from a fiber layer (nonwoven fabric) to be measured to obtain a measurement sample, a droplet of ion-exchanged water was attached to a surface to be measured of a contact angle of the measurement sample, the droplet was recorded, and the contact angle was measured based on an image recorded with the droplet. More specifically, as the measurement device, a microscope VHX-1000 manufactured by KEYENCE corporation, in which a medium magnification zoom lens is mounted in a state of being laid down at 90 °, was used. The measurement sample is placed on the measurement stage of the measurement device in a state in which the measurement surface is facing upward and the measurement sample can be observed from the CD direction. Then, a droplet of 3 μ L of ion-exchanged water was attached to the surface to be measured of the measurement sample placed on the measurement table, and an image of the droplet was recorded and read into the measurement apparatus. Among the plurality of images recorded, 10 droplets of the liquid were selected from the images with clear both ends or one end in the CD direction, and the contact angles of the droplets were measured for each of the 10 images, and the average value of the contact angles was used as the contact angle of the fiber layer (nonwoven fabric) to be measured. The measurement environment was set at 20 ℃/50% RH.

The first layer 11 is mainly composed of hydrophilic fibers 14, and thus becomes a hydrophilic layer. The second layer 12 is mainly composed of the hydrophobic fibers 15, and thus becomes a hydrophobic layer. The first layer 11 contains at least 50 mass% or more of the hydrophilic fiber 14, and the content of the hydrophilic fiber 14 may be 100 mass% with respect to the total mass of the first layer 11. The second layer 12 contains at least 70 mass% or more of the hydrophobic fibers 15, and the content of the hydrophobic fibers 15 may be 100 mass% based on the total mass of the second layer 12.

In the present invention, the degree of hydrophilicity of the fiber is determined based on the contact angle with water measured by the following method, and if the contact angle is less than 90 degrees, the fiber is hydrophilic, and if the contact angle is 90 degrees or more, the fiber is hydrophobic. The smaller the contact angle with water measured by the following method, the higher the hydrophilicity (the lower the hydrophobicity), and the larger the contact angle, the lower the hydrophilicity (the higher the hydrophobicity). In the laminated nonwoven fabric 10, the contact angle of the hydrophilic fibers 14 constituting the first layer 11 of the laminated structure 13 measured by the following method is less than 90 degrees, and the contact angle of the hydrophobic fibers 15 constituting the second layer 12 measured by the following method is 90 degrees or more.

< method for measuring contact Angle >

The fibers were taken out from the measurement object (laminated nonwoven fabric), and the contact angle of water with respect to the fibers was measured. When the fibers are taken out, scissors and tweezers are used, and the taking-out portions of the fibers of the laminated nonwoven fabric to be measured are the outermost surfaces (outermost surfaces) of the first surface and the second surface, respectively, and the region sandwiched between the first surface and the second surface of the laminated nonwoven fabric. As the measurement device, an automatic contact angle meter MCA-J manufactured by Kyowa Kagaku K.K. was used. Deionized water was used in the determination of the contact angle. The amount of liquid discharged from an ink-jet type water droplet discharge unit (pulse jet CTC-25 having a discharge unit pore size of 25 μm, manufactured by Cluster Technology) was set to 15 picoliters, and water droplets were dropped onto the top of the fibers. The dripping is recorded in a high-speed video recording device connected to a horizontally arranged camera. From the viewpoint of performing image analysis later, it is preferable that the recording device is a personal computer incorporating a high-speed capture device. In this assay, images were recorded every 17 msec. In the recorded image, the image analysis was performed on the initial image in which the water droplets were dropped on the fiber by using the satellite software FAMAS (version of software 2.6.2, droplet analysis method, θ/2 analysis method, no reflection in the image processing algorithm, frame image processing mode, threshold level of 200, no curvature correction), and the angle formed by the surface of the water droplets in contact with the air and the fiber was calculated as the contact angle. The fiber taken out of the object was cut to a fiber length of 1mm, and the fiber was placed on a sample table of a contact angle meter and kept horizontal. For one fiber, the contact angles at two different positions were measured. The contact angle of 5 fibers was measured up to 1 position after the decimal point, and the average value of the measurement values at 10 points in total (rounded up to 2 position after the decimal point) was defined as the contact angle of the fiber with water. The measurement environment was set at room temperature 22. + -. 2 ℃ and humidity 65. + -. 2% RH. The smaller the value of this contact angle, the higher the hydrophilicity.

In addition, in the case where a component (for example, a topsheet or a sweat-absorbing sheet) of an absorbent article contains a measurement sample (for example, a fiber), as a method for collecting the measurement sample, in the case where the component containing the measurement sample is fixed to another component by an adhesive, welding or the like, it is necessary to adopt a method of releasing the fixation and taking out the component containing the measurement sample from the absorbent article, but in the case where the component containing the measurement sample is not fixed to another component, a method of directly collecting the measurement sample from the absorbent article may be adopted. In addition, as a method of releasing the fixation of the component members, it is preferable to adopt a method of carefully taking out the component member to be measured after an adhesive or the like for joining the component member to be measured and another component member is weakened by a cooling device such as a cold spray device in the absorbent article. This extraction method is applied to the measurement of the measurement object of the present invention, such as the measurement of the distance between fibers and the fineness, which will be described later. In addition, from the viewpoint of minimizing the influence on the hydrophilizing agent applied to the constituent member, it is preferable to use a method of removing the fixed portion without causing the possibility of deterioration or loss of the oil agent, such as application of a solvent or blowing hot air with a blower.

As the hydrophobic fibers 15, hydrophobic thermoplastic fibers (hot melt fibers) can be used. As the material of the hydrophobic fibers 15, examples of the hydrophobic thermoplastic resin include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid, polyalkylmethacrylate, polyvinyl chloride, polyvinylidene chloride, and the like, and one of them may be used alone or two or more of them may be used in combination.

On the other hand, as the hydrophilic fibers 14, hydrophilic thermoplastic fibers (hot melt fibers) may be used, and specifically, for example, thermoplastic fibers having hydrophilicity per se such as polyacrylonitrile fibers may be used, or hydrophilic thermoplastic fibers usable as the hydrophobic fibers 15 may be used, and one of them may be used alone or two or more of them may be used in combination. Examples of the latter "thermoplastic fibers after hydrophilization treatment" include thermoplastic fibers to which a hydrophilizing agent is added, thermoplastic fibers to the surface of which a hydrophilizing agent is attached, and thermoplastic fibers subjected to plasma treatment. The hydrophilizing agent is not particularly limited as long as it is a conventional hydrophilizing agent used in sanitary goods.

The hydrophilic fibers 14 and the hydrophobic fibers 15 may be single fibers each composed of one synthetic resin (thermoplastic resin) or a blend polymer in which two or more synthetic resins are mixed, or may be composite fibers. The composite fiber as used herein refers to a synthetic fiber (thermoplastic fiber) obtained by simultaneously spinning two or more synthetic resins (thermoplastic resins) having different components by a spinneret, and is formed by bonding a plurality of components to each other in a structure in which the components are continuous in the longitudinal direction of the fiber. The form of the composite fiber is not particularly limited, and may be a core-sheath type, a side-by-side type, or the like.

The first layer 11 and the second layer 12 may be nonwoven fabrics mainly composed of short fibers (short fiber nonwoven fabrics) or nonwoven fabrics mainly composed of long fibers (long fiber nonwoven fabrics). The term "mainly" as used herein means that the proportion of the short fibers or long fibers in the total mass of the nonwoven fabric is 70 mass% or more, and the proportion is usually 100 mass%.

Examples of the short-fiber nonwoven fabric include a hot-air nonwoven fabric, a spunlace nonwoven fabric, a needle-punched nonwoven fabric, and a chemically bonded nonwoven fabric, and the fiber length of the main constituent fibers (short fibers) of the nonwoven fabric is preferably 15mm to 100 mm.

In the present invention, the "long fiber" means a fiber having a fiber length of 30mm or more. In particular, in the case of a so-called continuous filament having a fiber length of 150mm or more, a long fiber nonwoven fabric having high breaking strength can be obtained, which is preferable. The upper limit of the fiber length of the "long fibers" is not particularly limited. The term "long fiber nonwoven fabric" typically refers to a nonwoven fabric including a fiber assembly in which long fibers are intermittently fixed by heat-sealing portions. Examples of such a long fiber nonwoven fabric include a single layer nonwoven fabric such as a spunbond nonwoven fabric and a meltblown nonwoven fabric, a laminated nonwoven fabric obtained by laminating a spunbond layer mainly composed of long fibers, a meltblown layer, and the like, and a hot-rolled nonwoven fabric obtained by carding, and examples of the laminated nonwoven fabric include a spunbond-spunbond laminated nonwoven fabric (SS nonwoven fabric), a spunbond-spunbond laminated nonwoven fabric (SSs nonwoven fabric), a spunbond-meltblown-spunbond laminated nonwoven fabric (SMS nonwoven fabric), and a spunbond-meltblown-spunbond nonwoven fabric (SMMS nonwoven fabric).

In the method for producing a laminated nonwoven fabric of the present invention to be described later, the hydrophilic base nonwoven fabric which finally becomes the first layer 11 is conveyed, and the hydrophobic fibers 15 obtained by spinning a resin are deposited on the base nonwoven fabric being conveyed to obtain a laminate, in this case, in the laminated nonwoven fabric 10 produced by the production method by the direct spinning method, the first layer 11 may be a short fiber nonwoven fabric or a long fiber nonwoven fabric, but the second layer 12 containing the hydrophobic fibers 15 directly spun is a long fiber nonwoven fabric. In general, long fiber nonwoven fabrics are superior in strength to short fiber nonwoven fabrics.

As one of other main features of the laminated nonwoven fabric 10, there are two types of "small-thickness welded portions" in which the constituent fibers are welded to each other and have a smaller thickness than the peripheral portion. That is, the laminated structure 13 has an interlayer welded portion 16 in which the layers constituting the laminated structure 13 are welded to each other and the thickness is smaller than the peripheral portion, and the first layer 11 constituting the laminated structure 13 has an interfiber welded portion 17 in which the constituent fibers of the first layer 11 are welded to each other and the thickness is smaller than the peripheral portion, in addition to the interlayer welded portion 16. In the interlayer fusion part 16, the constituent fibers of the layers (in the illustrated embodiment, the first layer 11 and the second layer 12) constituting the laminated structure 13 are thermally fused to each other, and the layers are fused to each other. In the laminated structure 13 having such a configuration, the interlayer fusion parts 16 are formed in the same pattern on both the first surface 10a and the second surface 10b, and the interfiber fusion parts 17 formed only in the first layer 11 are also formed in a predetermined pattern on the first surface 10 a. In addition, the density of the small thickness weld is higher than that of the peripheral portion.

When the interlaminar fusion-bonded portion 16 and the interfiber fusion-bonded portion 17 are compacted parts obtained by compacting the constituent fibers in the thickness direction of the portion, the compaction is typically performed by embossing processing accompanied by a melting acceleration method of accelerating the melting of the thermoplastic fibers, which are constituent fibers, such as heat and ultrasonic waves, and specifically, for example, by heat sealing processing, ultrasonic sealing, or the like. When the manufacturing method is applied in this way, the interlayer fusion 16 and the interfiber fusion 17 may be referred to as an embossed portion, a pressed portion, or the like.

In the laminated nonwoven fabric 10, the interlayer weld 16 is formed by pressing the precursor of the laminated structure 13 (the laminated body of the first layer 11 and the hydrophobic fibers 15 as the base nonwoven fabric) from the second surface 10b side toward the first surface 10a side, and by this forming method, as shown in fig. 1, is recessed in a concave shape from the second surface 10b side toward the first surface 10a side. The interfiber fusion bond 17 is formed by pressing the precursor of the first layer 11 (web which is a deposition of the hydrophilic fibers 14) from the first surface 10a side to the second surface 10b side, and as a result of this forming method, as shown in fig. 1, is recessed in a concave shape from the first surface 10a side to the second surface 10b side. In the laminated nonwoven fabric 10, a plurality of interlayer fusion parts 16 are dispersed in the first surface 10a and the second surface 10b, respectively, and a plurality of interfiber fusion parts 17 are dispersed in the first surface 10 a. In the laminated nonwoven fabric 10, the first surface 10a and the second surface 10b are not flat surfaces having substantially no unevenness, but have unevenness.

In the case where the first surface 10a and/or the second surface 10b of the laminated nonwoven fabric 10 have/has irregularities as described above, for example, when the laminated nonwoven fabric 10 is used as a component (e.g., a topsheet or a sweat-absorbing sheet) that can be brought into contact with the skin of the wearer in an absorbent article, a space is formed between the laminated nonwoven fabric 10 and the skin of the wearer by disposing the laminated nonwoven fabric 10 so that the irregularities come into contact with the skin of the wearer, and moisture generated from body fluid such as excreted sweat or urine can be effectively emitted through the space, so that the feeling of dryness of the surface of the laminated nonwoven fabric 10 is improved, and the wearing feeling of the absorbent article can be improved.

Fig. 2 illustrates the pattern (planar shape and arrangement) of the interlayer weld 16. In addition, the pattern of the interlayer fusion 16 in the first surface 10a or the second surface 10b is not limited to the pattern shown in fig. 2, and a desired pattern may be adopted within a range not departing from the gist of the present invention.

Fig. 2 (a) to 2 (c) are each a pattern in which a plurality of interlayer fusion joints 16 having a predetermined shape in plan view are dispersed in a planar direction (a direction orthogonal to the thickness direction of the laminated nonwoven fabric 10). The shape of the interlayer fusion 16 in plan view is an ellipse (oblong shape) in fig. 2 a, a circle in fig. 2 b, and a quadrangle or rhombus in fig. 2 c. Fig. 2 (d) shows a pattern in which the linear interlayer welds 16 extend in a predetermined direction in plan view, and more specifically, a plurality of continuous linear interlayer welds 16 are arranged so as to intersect each other, and a lattice pattern is formed as an entire interlayer weld 16.

Fig. 3 illustrates a pattern of the inter-fiber fusion bonded portions 17. In the first surface 10a, the pattern of the inter-fiber fusion-spliced portion 17 is not limited to the pattern shown in fig. 3, and a desired pattern may be adopted within a range not departing from the gist of the present invention.

Fig. 3 (a) to 3 (e) are each a pattern in which a plurality of interfiber welds 17 having a predetermined shape are dispersed in the planar direction when viewed from above. The shape of the interfiber fusion splice 17 in plan view is elliptical in fig. 3 (a) and 3 (b), circular in fig. 3 (c), square or rhombic in fig. 3 (d), and cross-shaped in fig. 3 (e). While the longitudinal directions of the plurality of interfiber fusion splices 17 having an elliptical shape in plan view are aligned with each other in fig. 3 (a), a plurality of kinds of interfiber fusion splices 17 having an elliptical shape in plan view, which have different longitudinal directions, are dispersed in fig. 3 (b). As shown in fig. 3 (a) to 3 (e), in the dispersed pattern, the planar shape of the inter-fiber fusion-bonded portion 17 may be, for example, a polygonal shape such as a triangle, a pentagon or more, or a star shape, in addition to the illustrated shape. Fig. 3(f) to 3 (h) are patterns in which the inter-fiber fusion-bonded portions 17, which are linear in a plan view, are arranged so as to extend in a predetermined direction. In fig. 3(f), a plurality of continuous linear fusion-bonded portions 17 are arranged so as to intersect with each other, and a lattice pattern is formed as the entire fusion-bonded portions 17. Fig. 3g is a pattern in which the inter-fiber fusion-bonded portions 17 are changed from a continuous straight line to a discontinuous line in the lattice pattern of fig. 3 f, that is, a pattern using discontinuous lines (intermittent lines) in which relatively short line segments of the inter-fiber fusion-bonded portions 17 are intermittently arranged in a predetermined one direction. Fig. 3 (h) shows another example of the pattern formed by the discontinuous linear inter-fiber fusion-bonded portions 17 in fig. 3 (g), and the inter-fiber fusion-bonded portions 17 are arranged in a honeycomb shape.

Fig. 4 illustrates a pattern in which both the interlayer fusion 16 and the fiber fusion 17 are formed, that is, both the fusion 16 and the fusion 17 are formed on the first surface 10a of the laminated nonwoven fabric 10. In the first surface 10a, the pattern of the fusion-bonded

portions

16 and 17 is not limited to the pattern shown in fig. 4, and a desired pattern may be adopted without departing from the spirit of the present invention.

Fig. 4 (a) is a combination of the dispersed pattern of the interlayer fusion 16 of fig. 2 (a) and the dispersed pattern of the inter-fiber fusion 17 of fig. 3 (a), fig. 4 (b) is a combination of the dispersed pattern of the interlayer fusion 16 of fig. 2(b) and the linear pattern of the inter-fiber fusion 17 of fig. 3 (h), fig. 4 (c) is a combination of the linear pattern of the interlayer fusion 16 of fig. 2 (d) and the dispersed pattern of the inter-fiber fusion 17 of fig. 3 (c), and fig. 4 (d) is a combination of the dispersed pattern of the interlayer fusion 16 of fig. 2 (c) and the dispersed pattern of the inter-fiber fusion 17 of fig. 3 (d).

In addition to the above-described features, the laminated nonwoven fabric 10 has a feature that, when the ratio of the total area of the interlayer fusion 16 and the inter-fiber fusion 17 in the surface to the area of each of the first surface 10a and the second surface 10b is referred to as the fusion area ratio of the respective surfaces, that is, when the ratio of the total area of the interlayer fusion 16 and the inter-fiber fusion 17 in the first surface 10a to the area of the first surface 10a is referred to as the fusion area ratio of the first surface 10a, and the ratio of the total area of the interlayer fusion 16 and the inter-fiber fusion 17 in the second surface 10b to the area of the second surface 10b is referred to as the fusion area ratio of the second surface 10b, the first surface 10a has a larger fusion area ratio than the second surface 10b (the fusion area ratio of the first surface 10a > the fusion area ratio of the second surface 10b) Is true).

In the laminated nonwoven fabric 10 having the above-described characteristics, the second surface 10b is basically a surface which hardly absorbs body fluid (aqueous liquid) such as sweat or urine because the second layer 12 forming the surface is a hydrophobic layer containing the hydrophobic fibers 15, but since the hydrophilic fibers 14 of the first layer 11 which is a layer adjacent to the second layer 12 and has a higher degree of hydrophilicity are present relatively densely in addition to the hydrophobic fibers 15 in the interlayer weld 16 and its periphery in the second surface 10b, the degree of hydrophilicity is higher than that in other portions in the second surface 10b (the contact angle measured by the above-described method is small), and therefore, body fluid preferentially adheres to the interlayer weld 16 and its periphery in the second surface 10 b. In addition, as described above, since the laminated structure 13 has a hydrophilicity gradient in the thickness direction Z, such that "the first surface 10a side has a relatively high hydrophilicity as compared with the second surface 10b side", the laminated nonwoven fabric 10 has a capillary force excellent in liquid absorbability from the second surface 10b to the inside in the thickness direction Z. Therefore, the liquid adhered to the interlayer weld 16 and the periphery thereof on the second surface 10b is rapidly drawn into the laminated nonwoven fabric 10 mainly through the peripheral edge portion of the interlayer weld 16 and the vicinity thereof, and the hydrophilic first layer 11 has a hydrophilicity gradient of "the hydrophilicity on the first surface 10a side is relatively low and the hydrophilicity on the second surface 10b side is relatively high", and therefore, the liquid is absorbed and held by the hydrophilic first layer 11 on the inner side in the thickness direction Z while spreading in the surface direction (the direction orthogonal to the thickness direction Z) of the laminated nonwoven fabric 10. In the second surface 10b, the liquid introduction portion is mainly "the peripheral edge portion of the interlayer welded portion 16 and its vicinity". In general, even if the fiber form of the constituent fibers in the central portion of the interlayer fusion 16 is lost and made into a film, the fiber form is not maintained at the peripheral edge portion of the interlayer fusion 16 and its vicinity (the periphery of the interlayer fusion 16) other than the central portion of the interlayer fusion 16, and therefore the peripheral edge portion of the interlayer fusion 16 and its vicinity serve as the liquid inlet portion of the second surface 10 b.

From the viewpoint of further improvement in liquid absorbency by the above-described hydrophilicity gradient, the contact angle of the constituent fibers (hydrophobic fibers 15) of the second layer 12 is preferably 95 degrees or more, more preferably 100 degrees or more, and preferably 150 degrees or less, more preferably 130 degrees or less, as compared with the constituent fibers (hydrophilic fibers 14) of the first layer 11. The contact angle of the constituent fibers (hydrophilic fibers 14) of the first layer 11 is preferably 15 degrees or more, more preferably 20 degrees or more, and preferably 88 degrees or less, more preferably 85 degrees or less, on the assumption that the contact angle is smaller than the constituent fibers (hydrophobic fibers 15) of the second layer 12. The degree of hydrophilicity of the constituent fibers can be adjusted by appropriately adjusting the degree of hydrophilization treatment of the thermoplastic fibers, which are the main constituent fibers of the laminated nonwoven fabric 10, for example, the type and content of the hydrophilizing agent.

As described above, the interlayer weld 16 is an important part of the liquid intake portion at the peripheral edge portion and the vicinity thereof when liquid is absorbed from the hydrophobic second surface 10b, but in the interlayer weld 16, since the hydrophobic second layer 12 and the hydrophilic first layer 11 are joined, when the laminated nonwoven fabric 10 is compressed in the thickness direction after liquid absorption (for example, when the laminated nonwoven fabric 10 is used as a component of an absorbent article so that the second surface 10b faces the skin side of a wearer, when the body pressure of the wearer is applied to the laminated nonwoven fabric 10), so-called liquid backflow may occur in which liquid absorbed and held by the first layer 11 flows back to the second surface 10b side via the peripheral edge portion and the vicinity thereof of the interlayer weld 16. However, since the inter-fiber fusion-bonded portion 17 in which only the constituent fibers (hydrophilic fibers 14) of the first layer 11 are fused together is formed in the first layer 11 separately from the interlayer fusion-bonded portion 16, and the liquid is diffused in the planar direction along the portion around the inter-fiber fusion-bonded portion 17 where the fibers are dense, the backflow of the liquid toward the second surface 10b side can be effectively suppressed.

From the viewpoint of more reliably achieving the above-described effects (both liquid absorption and liquid backflow prevention), the ratio of the welded portion area ratio of the first surface 10a (the former) to the welded portion area ratio of the second surface 10b (the latter) (i.e., the ratio of the welded portion area ratio of the first surface 10a to the welded portion area ratio of the second surface 10b) is preferably 1.3 or more, more preferably 1.4 or more, and further preferably 3.0 or less, and even more preferably 2.5 or less, when expressed as former/latter. When this ratio is too small, the liquid-backflow resistance is not easily obtained, and conversely, when it is too large, the amount of liquid that can be absorbed and retained by the hydrophilic first layer 11 may decrease.

When both the interlayer fusion-bonded part 16 and the fiber fusion-bonded part 17 are formed on the first surface 10a, the patterns of the fusion-bonded

parts

16 and 17 may be the same, but the patterns of the fusion-bonded

parts

16 and 17 are preferably different from each other from the viewpoint of more reliably achieving the above-described operation and effect. More specifically, the interlayer fusion-bonded portions 16 and the interfiber fusion-bonded portions 17 preferably differ in at least two of arrangement pattern, planar shape of the individual fusion-bonded portions, area of the individual fusion-bonded portions, distance between fusion-bonded portions (shortest distance between fusion-bonded portions) D16, D17 (see fig. 1), pitch P16, and pitch P17 (see fig. 1). Here, the inter-fusion-bonded portion distances D16 and D17 are intervals between two adjacent fusion-bonded portions (interlayer fusion-bonded portions 16 or inter-fiber fusion-bonded portions 17) in the plane direction of the laminated nonwoven fabric 10, and the pitches P16 and P17 are distances between the centers of the two fusion-bonded portions in a plan view.

Both the interlayer fusion bonded portions 16 and the inter-fiber fusion bonded portions 17 are high-density fusion bonded portions in which the constituent fibers are fused to each other at a density higher than the peripheral portion, and the fiber form of the thermoplastic fibers as the constituent fibers may be lost and filmed depending on the pressure and heating conditions at the time of formation, but from the viewpoint of more reliably achieving the above-described operational effects, the inter-fiber fusion bonded portions 17 are preferable to maintain the fiber form of the constituent fibers as compared with the interlayer fusion bonded portions 16. Specifically, for example, in the case where the constituent fibers of the interlayer fusion parts 16 are formed into a film, the constituent fibers of the inter-fiber fusion parts 17 are preferably not formed into a film while maintaining the fiber form. By relatively maintaining the fiber form of the constituent fibers of the inter-fiber fusion bonded part 17, the hydrophilic fibers 14 are present at a high density in the inter-fiber fusion bonded part 17 maintaining the fiber form, and the capillary pressure is high, so that the liquid retention performance of the inter-fiber fusion bonded part 17 and the periphery thereof can be further improved. In addition, since the fiber form of the fibers constituting the interlayer fusion 16 is relatively lost, the backflow of the liquid through the interlayer fusion 16 in which the fiber form is lost can be effectively prevented. The fiber form of the constituent fibers of the welded

portions

16 and 17 is mainly determined by the conditions of the embossing process at the time of forming the welded

portions

16 and 17, and when the heating and pressing conditions at the embossing process are made relatively weak, the fiber form of the constituent fibers is easily maintained.

As described above, the peripheral edge portion of the interlayer weld 16 and the vicinity thereof are portions which become liquid introduction portions when liquid is absorbed from the second face 10b, and therefore, from the viewpoint of improving the liquid absorption of the laminated nonwoven fabric 10, the second face 10b preferably has an interlayer weld distribution region in which a plurality of interlayer welds 16 are distributed in the plane direction. In particular, when the laminated nonwoven fabric 10 is used as a sweat-absorbent sheet capable of absorbing sweat, the second surface 10b preferably has the above-described region where the interlayer welded portions are scattered, because sweat absorption can be further improved. The entire area of the second surface 10b may be the interlayer welded portion scattering area, or only a part of the second surface 10b may be the interlayer welded portion scattering area. The ratio of the area of the interlayer welded part scattering region to the total area of the second surface 10b is preferably 70% or more, and more preferably 80% or more.

In addition, when a circle having a radius of 2mm is virtually provided at an arbitrary position of the interlayer welded portion scattering area on the second surface 10b, it is preferable that at least a part or all of 1 interlayer welded portion 16 is included in the virtual circle, with respect to the arrangement of the interlayer welded portions 16 in the interlayer welded portion scattering area. Here, the phrase "in the case where a circle having a radius of 2mm is virtually provided at an arbitrary position, a part or all of 1 interlayer fusion 16 is included in the virtual circle" means that "in the case where 10 virtual circles are provided in the region where the interlayer fusion 16 is scattered on the second surface 10b, the interlayer fusion 16 may not be included at all in 1 or 2 of the 10 virtual circles, as long as the remaining 8 virtual circles include at least a part or all of 1 interlayer fusion 16". The virtual circle is a circle assumed to be spread over sweat secretion sites (sweat glands) on the skin surface of a human body, and the laminated nonwoven fabric 10 having the above-described structure can absorb sweat more efficiently. In particular, when the radius of the imaginary circle is 1.5mm, it is more effective when the interlayer welded portion 16 is disposed so as to satisfy the above-described condition.

Since the peripheral edge portion of the interlayer weld 16 and the vicinity thereof are liquid intake portions of the second surface 10b, in order to ensure practically sufficient liquid absorbency, a certain number is required, that is, the peripheral length of the interlayer weld 16 needs to have a length of at least a certain extent, but the area of the interlayer weld 16 itself is not preferably too large, and when the interlayer weld 16 is excessively present on the second surface 10b, not only the hydrophobic second layer 12 but also the hydrophilic first layer 11 are welded together in the interlayer weld 16, and therefore the amount of liquid that can be absorbed and held by the first layer 11 may possibly decrease. From this viewpoint, the ratio of the total area of the interlayer fusion 16 (the sum of the areas of the plurality of interlayer fusion 16 when the plurality of interlayer fusion 16 are formed on the second surface 10b) to the area of the second surface 10b, that is, the area ratio of the interlayer fusion 16 is preferably 15% or less, and more preferably 12% or less. The lower limit of the ratio is preferably 5% or more, and more preferably 6% or more.

Further, since the interlayer welded portion 16 is continuous over the entire thickness direction Z of the laminated structure 13 (laminated nonwoven fabric 10), and the patterns (planar shape and arrangement) of the interlayer welded portion 16 are substantially the same on the first surface 10a and the second surface 10b, the description of the pattern of the interlayer welded portion 16 of the second surface 10b (the above-described region where the interlayer welded portions are scattered, the area ratio of the interlayer welded portion 16, and the like) in the present specification is also applicable to the first surface 10a unless otherwise specified.

The interlayer fusion 16 is preferably shorter in pitch than the interfiber fusion 17. That is, referring to fig. 1, it is preferable that a magnitude relation of "pitch P16 of interlayer fusion 16 < pitch P17 of inter-fiber fusion 17" is established. With this structure, since absorption is possible from the moment when sweat begins to be produced and the amount of sweat is small, and the absorption capacity of the first layer 11 is large, the above-described operational effects (both liquid absorption and liquid-backflow prevention properties) can be more reliably achieved.

From the same viewpoint, the interlayer fusion 16 is preferably shorter in the distance between fusion points (the shortest distance between fusion points) than the interfiber fusion 17. That is, referring to fig. 1, it is preferable that a magnitude relationship of "the inter-fusion-part distance D16 of the interlayer fusion part 16 < the inter-fusion-part distance D17 of the inter-fiber fusion part 17" is established. In addition, the structure relating to the distance between the welded portions is effective particularly when the pattern is a pattern in which the plurality of interlayer welded portions 16 and the plurality of inter-fiber welded portions 17 are arranged in a dispersed manner in a plan view, for example, the pattern shown in fig. 2 (a) to 2 (c) is applied to the interlayer welded portions 16, and the pattern shown in fig. 3 (a) to 3 (e) is applied to the inter-fiber welded portions 17.

In addition, from the viewpoint of achieving both the liquid absorbability and the liquid-backflow prevention property, the area of the 1 interlayer welded part 16 on the second surface 10b was 0.3mm²Hereinafter, the area of the first surface 10a is preferably smaller than 1 inter-fiber fusion-bonded part 17. The area of the interlayer weld 16 on the second face 10b is preferably 0.25mm²Hereinafter, the lower limit is preferably 0.1mm²Above, more preferably 0.15mm²The above. The ratio of the area of the 1 interlayer fusion 16 on the second surface 10b (the former) to the area of the 1 interfiber fusion 17 on the first surface 10a (the latter) (i.e., the ratio of the area of the 1 interlayer fusion 16 on the second surface 10b to the area of the 1 interfiber fusion 17 on the first surface 10a) is preferably 0.25 or more, more preferably 0.3 or more, and preferably 0.8 or less, and even more preferably 0.75 or less, expressed as "former/latter". In addition, this structure is particularly effective when the pattern is a pattern in which a plurality of interlayer fusion-bonded portions 16 and inter-fiber fusion-bonded portions 17 are arranged in a dispersed manner in a plan view, for example, when the pattern is the pattern shown in fig. 2 (a) to 2 (c) for the interlayer fusion-bonded portions 16, and when the pattern is the pattern shown in fig. 3 (a) to 3 (e) for the inter-fiber fusion-bonded portions 17.

The grammage of the first layer 11 and the second layer 12 is not particularly limited as long as it is appropriately adjusted according to the use of the laminated nonwoven fabric 10 and the like. For example, when the laminated nonwoven fabric 10 is used as a component (topsheet, sweat-absorbing sheet, etc.) of an absorbent article such as a disposable diaper and a sanitary napkin, the combined grammage of the first layer 11 and the second layer 12 is preferably 8g/m from the viewpoint of ensuring practically sufficient strength without increasing the bulk²Above, more preferably 10g/m²Above, and preferably 30g/m²Hereinafter, it is more preferably 27g/m²The following.

Particularly, when the hydrophobic second layer 12 (second surface 10b) is to be brought into first contact with the liquid to be absorbed, the hydrophilic first layer 11 is the peripheral edge portion and the interlayer weld 16 with the second surface 10b of the second layer 12In the layer related to the liquid absorption force in the vicinity thereof, the higher the grammage of the first layer 11, the higher the absorption force, and the higher the strength. On the other hand, when the grammage of the first layer 11 is too large, the bulk increases or the rigidity increases, and as a result, when used as a component of an absorbent article, the wearing feeling may be deteriorated. When the above is considered, the grammage of the first layer 11 is preferably 5g/m²Above, more preferably 7g/m²Above, preferably 25g/m²Hereinafter, it is more preferably 20g/m²The following.

In addition, the hydrophobic second layer 12 is usually a layer which is first in contact with a liquid when the laminated nonwoven fabric 10 is used for liquid absorption, and in such a use mode, when the grammage of the second layer 12 is relatively small and the thickness is thin, the liquid is easily absorbed through the peripheral edge portion of the interlayer welded portion 16 of the second face 10b and the vicinity thereof. When the grammage of the second layer 12 is too small, the strength may be reduced and the liquid may flow back. When the above is considered, the grammage of the second layer 12 is preferably 3g/m²Above, more preferably 5g/m²Above, preferably 15g/m²Hereinafter, it is more preferably 13g/m²The following. In addition, when the second layer 12 is 3g/m²In the case of a low grammage of about two, the strength of the second layer 12 may become insufficient, and the production of the laminated nonwoven fabric 10 may become difficult, but according to the method for producing a laminated nonwoven fabric of the present invention to be described later, the second layer 12 is produced by a so-called direct spinning method, and therefore such a possibility is eliminated.

As described above, various nonwoven fabrics can be used as the first layer 11 and the second layer 12, but in the case of using the laminated nonwoven fabric 10 for liquid absorption applications such as when it is used as a component of an absorbent article, from the viewpoint of more reliably achieving the above-described operational effects, a spunbond nonwoven fabric coated with a hydrophilizing agent or an SMS nonwoven fabric coated with a hydrophilizing agent is particularly preferable as the hydrophilic first layer 11.

Another preferable example of the hydrophilic first layer 11 is a hydrophilic first layer containing 70 mass% or more, preferably 75 mass% or moreThe above-mentioned hydrophilic fibers 14, and the inter-fiber fusion bonded portions 17 are formed on the entire air-through nonwoven fabric. In this through-air nonwoven fabric, the area of 1 interfiber weld 17 is preferably 0.2mm²Above, further preferably 0.3mm²Above, and preferably 1mm²Hereinafter, more preferably 0.8mm²The following. The number of the inter-fiber fusion-bonded parts 17 present per unit area of 10mm square on one surface of such a hot-air nonwoven fabric is preferably 4 or more, more preferably 6 or more, and preferably 30 or less, more preferably 28 or less.

On the other hand, the hydrophobic second layer 12 is preferably a spunbonded nonwoven fabric, a meltblown nonwoven fabric, or a laminated nonwoven fabric (for example, SMS nonwoven fabric) thereof, because it is considered to be relatively thin and relatively easy to absorb liquid.

The hydrophilic fibers 14, which are the main constituent fibers of the first layer 11, are typically obtained by hydrophilizing thermoplastic fibers that are originally hydrophobic. That is, the first layer 11 can be said to be a layer obtained by subjecting an aggregate of hydrophobic fibers (for example, thermoplastic fibers that can be used as the constituent fibers of the second layer 12) to a hydrophilization treatment. As the hydrophilization treatment, as described above, plasma treatment or the like may be used in addition to coating a hydrophilizing agent on the fiber or the fiber aggregate and doping the fiber with the hydrophilizing agent, but the treatment with the hydrophilizing agent is usually performed.

As an example of the first layer 11, there is a form in which a hydrophilizing agent is applied to the second surface 10b (the hydrophilizing agent adheres to the surface of the constituent fiber on the second surface 10 b). The second surface 10b side of the first layer 11 is opposite to the first surface 10a, and is a contact surface side of a layer adjacent to the first layer 11, that is, a layer having a lower degree of hydrophilicity than the first layer 11 (in the form shown in fig. 1, the hydrophobic second layer 12). In the first layer 11 of this embodiment, the hydrophilizing agent adhering to the surface of the fibers is more biased toward the second surface 10b than toward the first surface 10a, and therefore the first layer 11 has a gradient of hydrophilicity such that the hydrophilicity is relatively low toward the first surface 10a and the hydrophilicity is relatively high toward the second surface 10 b. As described above, in the first layer 11, when the hydrophilicity on the second surface 10b side is higher than that on the first surface 10a side, a hydrophilicity gradient is formed in the laminated structure 13 such that the hydrophilicity increases stepwise (the contact angle measured by the above method decreases stepwise) from the hydrophobic second layer 12 (second surface 10b) which is initially in contact with the liquid to be absorbed toward the inside in the thickness direction Z of the laminated structure 13, and thus further improvement in the liquid absorbability can be expected.

The method for applying the hydrophilizing agent is not particularly limited, and a known method capable of applying a coating solution containing the hydrophilizing agent can be suitably used. As a usable coating method, gravure coating, roll lick coating, flexographic printing, spray coating, reverse coating, die coating are preferable, and among them, gravure coating, flexographic coating, spray coating, die coating which can be applied in a pattern are particularly preferable. In addition, as the hydrophilizing agent, various surfactants used for hydrophilizing constituent members of absorbent articles such as disposable diapers and the like can be used without particular limitation.

Another example of the first layer 11 is a hydrophilic nonwoven fabric containing constituent fibers doped with a hydrophilizing agent. In the first layer 11 of this form, the hydrophilizing agent is not attached to the surface of the hydrophilic fiber 14, which is a main constituent fiber thereof, but is contained in the hydrophilic fiber 14. While the first layer 11 in the form of being coated with the hydrophilizing agent from one surface side has a gradient in hydrophilicity in the thickness direction Z, the first layer 11 in the form of being doped with the hydrophilizing agent in the constituent fibers does not have a gradient in hydrophilicity but has a uniform hydrophilicity in the thickness direction Z on the premise that the constituent fibers are uniformly distributed over the entire first layer 11.

The liquid absorbency of the laminated nonwoven fabric 10 is not only affected by the above-described gradient of the degree of hydrophilicity in the thickness direction, but also affected by the thickness of the hydrophobic second layer 12. In the hydrophobic nonwoven fabric, the small distance between fibers and the large thickness are factors for increasing the water resistance. Therefore, when the hydrophobic second layer 12 (second surface 10b) is a layer (a layer into which a liquid is introduced) that is first brought into contact with a liquid to be absorbed, the second layer 12 preferably has a small thickness and a low fiber density (a long distance between fibers) in order to improve the liquid absorbability of the laminated nonwoven fabric 10. On the other hand, the hydrophilic layer (in the illustrated embodiment, the first layer 11) adjacent thereto preferably has a high fiber density (short distance between fibers) because the capillary force is high and water can be absorbed through the hydrophobic layer. In the interlayer weld 16 and its surroundings, the hydrophilic fibers of the first layer 11 having a high fiber density (short interfiber distance) are easily exposed from the space between the fibers of the second layer 12 (second surface 10b) having a relatively low fiber density (long interfiber distance) to the second surface 10b side, and liquid is more stably and rapidly introduced into the interior from the peripheral edge portion of the interlayer weld 16 of the second surface 10b and its vicinity, and the introduced liquid is absorbed and held in the hydrophilic first layer 11. From this viewpoint, the first layer 11 preferably has a higher fiber density than the second layer 12, that is, the distance between fibers constituting the fibers is preferably short. The distance between fibers was measured by the following method.

< method for measuring distance between fibers >

The distance between fibers of a fiber aggregate such as a nonwoven fabric or paper is determined by the following formula (1) based on the assumption of Wrotnowski. The following formula (1) is generally used for determining the distance between fibers of a fiber aggregate. Under the assumption of Wrotnowski, the fibers are cylindrical and the fibers do not intersect but are orderly arranged.

When the measurement target sheet (the first hydrophilic layer 11A, the second hydrophilic layer 11B, and the water-repellent layer 12) has a single-layer structure, the distance between fibers of the single-layer structure sheet is determined by the following formula (1).

When the measurement target sheet (first hydrophilic layer 11A, second hydrophilic layer 11B, and water-repellent layer 12) has a multilayer structure, such as an SMS nonwoven fabric, the distance between fibers of the sheet having the multilayer structure is determined in the following procedure.

First, the distance between fibers of each fiber layer constituting the multilayer structure is calculated by the following formula (1). In this case, the thickness t, the grammage W, the resin density ρ of the fiber, and the fiber diameter D used in the following formula (1) are the thickness t, the grammage W, the resin density ρ of the fiber, and the fiber diameter D of the layer to be measured, respectively. The thickness t, the grammage W and the fiber diameter D are average values of the measured values at a plurality of measurement points.

The thickness t (mm) is measured by the following method. First, a measurement target sheet was cut into a length direction of 50mm × a width direction of 50mm, and cut pieces of the sheet were prepared. However, when a cut piece having such a size cannot be produced as a measurement target piece, for example, when a piece is taken out from a small absorbent article, the cut piece is produced as large as possible. Next, the cut piece was placed on a flat plate, a flat glass plate was placed thereon, weights were placed uniformly on the glass plate so that the load including the glass plate became 49Pa, and then the thickness of the cut piece was measured. The measurement environment was 20. + -. 2 ℃ and the relative humidity was 65. + -. 5%, and the measuring apparatus used was a microscope (VHX-1000, manufactured by Keyence, Ltd.). The thickness of the cut piece is measured by first obtaining an enlarged photograph of the cut surface of the cut piece. In the magnified photograph, an object of known size is simultaneously taken. Next, the scale is aligned with the enlarged photograph of the cut surface of the cut piece, and the thickness of the cut piece, that is, the thickness of the measurement target piece is measured. The above operation was performed 3 times, and the thickness t of the target sheet was measured as an average value of the 3 times. When the sheet to be measured is a laminate, the boundary is determined from the fiber diameter, and the thickness is calculated.

Gram weight W (g/m)²) The mass is measured by cutting a piece to be measured into a predetermined size (for example, 12 cm. times.6 cm), and then dividing the mass measurement value by the area obtained from the predetermined size to obtain the mass measurement value (gram weight W (g/m)²) Mass ÷ area determined from a predetermined size "). The weight was measured 4 times, and the average value was determined as the gram weight.

Resin density of fiber rho (g/cm)³) The measurement was performed using a density gradient tube according to the measurement method of the density gradient tube method described in JIS L1015 chemical fiber short fiber test method (URL described in http: html, if it is a book, it is described in JIS manual, fiber-2000, (p.764-765 of japan standards association).

Fiber diameter D (. mu.m) fiber sections of 10 cut fibers were measured using a field emission scanning electron microscope model S-4000, manufactured by Hitachi, Ltd, and the average value was used as the fiber diameter. The fiber diameter D was measured by the method described below.

Next, the distance between the fibers of each layer is multiplied by the ratio of the thickness of the layer to the thickness of the entire multilayer structure, and the values of the layers thus obtained are summed up to obtain the distance between the fibers of the constituent fibers of the intended sheet of the multilayer structure. For example, in an SMS nonwoven fabric having a 3-layer structure including 2S layers and 1M layer, the 2S layers are collectively treated as 1 layer, and when the thickness t of the entire 3-layer structure is 0.11mm, the thickness t of the S layer is 0.1mm, the inter-fiber distance LS of the S layer is 47.8 μ M, the thickness t of the M layer is 0.01mm, and the inter-fiber distance LS of the M layer is 3.2 μ M, the inter-fiber distance of the constituent fibers of such an SMS nonwoven fabric becomes 43.8 μ M [ (47.9 × 0.1+3.2 × 0.01)/0.11 ].

As described above, the ratio of the distance between the fibers of the first layer 11 (hydrophilic fibers 14) to the distance between the fibers of the second layer 12 (hydrophobic fibers 15) is preferably 1.1 or more, more preferably 10 or more, and preferably 70 or less, more preferably 50 or less, as the former/former, on the premise that the former < the latter.

The distance between the fibers (hydrophilic fibers 14) constituting the first layer 11 is preferably 5 μm or more, more preferably 7 μm or more, and preferably 100 μm or less, more preferably 80 μm or less.

The distance between the fibers constituting the second layer 12 (the hydrophobic fibers 15) is preferably 7 μm or more, more preferably 10 μm or more, and preferably 200 μm or less, more preferably 150 μm or less.

In addition, from the viewpoint of imparting a density gradient of fibers such that the fiber density is increased from the second layer 12 to the first layer 11 (the inner side in the thickness direction Z of the laminated structure 13) to improve the liquid absorbency, the constituent fibers (hydrophilic fibers 14) of the first layer 11 are preferably smaller in fiber diameter than the constituent fibers (hydrophobic fibers 15) of the second layer 12. The fiber diameter was measured by the following method.

< method for measuring fiber diameter >

The measurement object (fiber layer, laminated nonwoven fabric) was cut with a razor (e.g., a razor blade manufactured by feater safety razor) to obtain a measurement piece having a square shape (8mm × 4mm) in a plan view. When cutting the measurement object, attention is paid to a structure that does not break the cut surface of the measurement piece formed by cutting due to pressure or the like at the time of cutting. A preferable method for cutting the measurement object includes a method in which the measurement object is sufficiently frozen in liquid nitrogen before cutting the measurement object, and then the measurement object is cut. The measurement piece was attached to the sample table using a double-sided adhesive tape (Nicetack NW-15, manufactured by Nichiban corporation). Next, the test piece was coated with platinum. An ion sputtering apparatus E-1030 (trade name) manufactured by Nicolke precision instruments was used for coating, and the sputtering time was set to 30 seconds. The cut surface of the measurement piece was observed at 1000-fold magnification using a field emission scanning electron microscope model S-4000, manufactured by Hitachi, Ltd.

In the above-described method for measuring the fiber diameter, when the constituent fibers (hydrophilic fibers 14) of the first layer 11 are measured, the fibers connected to the inter-fiber fusion parts 17 are selected, when the constituent fibers (hydrophobic fibers 15) of the second layer 12 are measured, the constituent fibers (hydrophobic fibers 15) of the second layer 12 overlapping the inter-fiber fusion parts 17 are selected, the length in the width direction of each of 10 fibers with respect to the length direction of the fiber is measured, and the average value thereof is the fiber diameter.

In addition, when the measurement target is a composite nonwoven fabric composed of a plurality of fiber layers having different fiber diameters, such as an SMS nonwoven fabric and an SMMS nonwoven fabric, the liquid absorbency of the first layer 11 is greatly affected by the fine melt-blown layer having a high fiber density, and the liquid absorbency from the second surface 10b side is greatly affected by the fine melt-blown layer having a high fiber density of the second layer 12. In view of the above, when the measurement target is a composite nonwoven fabric including a meltblown layer and a plurality of fiber layers having different fiber diameters, the fiber diameter of the meltblown layer in the composite nonwoven fabric is measured when the fiber diameter is measured.

As described above, the ratio of the fiber diameter (former) of the constituent fibers (hydrophilic fibers 14) of the first layer 11 to the fiber diameter (latter) of the constituent fibers (hydrophobic fibers 15) of the second layer 12 [ that is, the ratio of the fiber diameter of the constituent fibers (hydrophilic fibers 14) of the first layer 11 to the fiber diameter of the constituent fibers (hydrophobic fibers 15) of the second layer 12 ] is preferably 0.05 or more, more preferably 0.06 or more, and preferably 0.9 or less, more preferably 0.8 or less, when expressed as the former/latter, on the premise that the former < the latter.

The fiber diameter of the constituent fibers (hydrophilic fibers 14) of the first layer 11 is preferably 0.5 μm or more, more preferably 1 μm or more, and is preferably 30 μm or less, more preferably 20 μm or less.

The fiber diameter of the constituent fibers (hydrophobic fibers 15) of the second layer 12 is preferably 3 μm or more, more preferably 5 μm or more, and preferably 40 μm or less, more preferably 30 μm or less.

From the viewpoint of improving the liquid absorbency of the laminated nonwoven fabric 10, the amount of the hydrophilic fibers 14, which are the main constituent fibers of the first layer 11, per unit area (the number of fibers) is preferably larger than that of the hydrophobic fibers 15, which are the main constituent fibers of the second layer 12. The amount of fiber per unit area was measured by the following method

< method for measuring amount of fiber per unit area >

First, in the same manner as the above < method of measuring fiber diameter >, the laminated nonwoven fabric 10 to be measured is cut with a razor so as to pass through the inter-fiber welded portions 17, to obtain a measurement piece. The cut surface of the piece was measured by magnifying observation (adjusted to a magnification of 150 to 500 times that can measure the cross section of about 30 to 60 fibers) using a scanning electron microscope, and counted for each fixed area (0.5 mm)²Left and right) of the cut surfaceThe number of faces. In the counting of the number of cross sections of the fibers, when the constituent fibers (hydrophilic fibers 14) of the first layer 11 are measured, the fibers connected to the inter-fiber fusion parts 17 are selected. When the constituent fibers (hydrophobic fibers 15) of the second layer 12 are measured, the constituent fibers (hydrophobic fibers 15) of the second layer 12 that overlap the interfiber fusion bonds 17 are selected. In the measurement of the constituent fibers (hydrophilic fibers 14) of the first layer 11, when it is difficult to define the fibers connected to the inter-fiber fusion splices 17, the number of the constituent fibers (hydrophilic fibers 14) of the first layer 11 is obtained by subtracting the number of the constituent fibers (hydrophobic fibers 15) of the second layer 12 overlapping the inter-fiber fusion splices 17 from the number of cross sections of the fibers of a certain area in the entire thickness direction in the vicinity of the inter-fiber fusion splices 17. The measurement was conducted at 3 points, and the average value was taken as the fiber amount.

As described above, the ratio of the fiber amount per unit area of the hydrophilic fibers 14 of the first layer 11 (former) to the fiber amount per unit area of the hydrophobic fibers 15 of the second layer 12 (latter) (i.e., the ratio of the fiber amount per unit area of the hydrophilic fibers 14 of the first layer 11 to the fiber amount per unit area of the hydrophobic fibers 15 of the second layer 12) is preferably 1.8 or more, more preferably 2.0 or more, further preferably 8 or less, and even more preferably 6 or less, when expressed as the former/latter, on the premise that the former > the latter.

The amount of the hydrophilic fibers 14 (number of fibers) per unit area in the first layer 11 is preferably 10 fibers/mm²More preferably 15 pieces/mm²Above, preferably 300 pieces/mm²Hereinafter, more preferably 200 pieces/mm²The following.

The hydrophobic fibers 15 of the second layer 12 preferably have a fiber amount per unit area (number of fibers) of 3 fibers/mm²Above, more preferably 5 pieces/mm²Above, preferably 100 pieces/mm²Hereinafter, more preferably 70 roots/mm²The following.

The laminated structure of the laminated nonwoven fabric of the present invention may have other layers in addition to the above-described hydrophilic first layer containing hydrophilic fibers and the hydrophobic second layer containing hydrophobic fibers. Specifically, for example, in the laminated nonwoven fabric 10 shown in fig. 1, a long fiber layer containing long fibers may be arranged on the second surface 10b side of the second layer 12. That is, the laminated nonwoven fabric 10 may have a multilayer structure of 3 or more layers including the first layer 11 forming the first surface 10a, the long fiber layer (not shown) forming the second surface 10b, and the second layer 12 interposed between these two layers.

The structure of the long fiber layer is not particularly limited, but from the viewpoint of improving the absorbency of liquid from the second surface 10b side, a hydrophilic layer is preferable, and a layer mainly composed of hydrophilic fibers is preferable. The hydrophilic fiber, which is the main constituent fiber of the long fiber layer, is not particularly limited, and the hydrophilic fiber that can be used in the first layer can be used. As an example of the long fiber layer, a fiber layer having a hydrophilic layer containing fibers doped with a hydrophilizing agent can be exemplified. The gram weight of the long fiber layer is not particularly limited, but is preferably 2g/m²Above, more preferably 3g/m²Above, further, it is preferably 10g/m²Hereinafter, more preferably 8g/m²The following.

Another embodiment of the laminated nonwoven fabric laminated structure of the present invention is a laminated nonwoven fabric 10 shown in fig. 1, in which an elastic member (not shown) is present between the first layer 11 and the second layer 12. In the case where the laminated structure 13 has a multilayer structure of 3 or more layers, the elastic member is not limited to be interposed between the first layer 11 and the second layer 12, and may be interposed between any of the layers. By interposing the elastic member between the layers of the laminated structure in this way, elasticity can be imparted to the laminated nonwoven fabric, and the range of applications of the laminated nonwoven fabric can be further expanded.

The elastic member preferably has a property (elasticity) that it can be stretched and returns to a length of 1.1 times or less the original length when a force is released from a state in which it is stretched 1.3 times the original length (to a length 1.3 times the original length). The inelastic member is a member having no such "elasticity", that is, having a property of not returning to a length 1.1 times or less the original length when a force is released from a state of being elongated 1.3 times the original length (becoming a length 1.3 times the original length). The form of the elastic member is not particularly limited, and any form such as a linear form, a sheet form, an aggregate of elastic fibers (elastic fiber layer), and the like can be selected. For example, in the laminated nonwoven fabric 10 (laminated structure 13) shown in fig. 1, a plurality of linear (filament) elastic members are arranged between the first layer 11 and the second layer 12 so as to extend in the same direction, and in this case, the laminated nonwoven fabric 10 (laminated structure 13) has stretchability in the direction in which the elastic members extend.

As a material of the elastic member, a resin material of natural rubber or a thermoplastic elastomer can be used, and examples of the resin material of the thermoplastic elastomer include styrene-based elastomers such as SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene), and SEPS (styrene-ethylene-propylene-styrene), olefin-based elastomers (ethylene-based α -olefin elastomers, propylene-based elastomers obtained by copolymerizing ethylene-butene-octene, and the like), polyester-based elastomers, and polyurethane-based elastomers.

Next, a method for producing a laminated nonwoven fabric according to the present invention will be described based on preferred embodiments thereof with reference to the drawings. Fig. 5 is a schematic view showing an example of the method for producing the laminated nonwoven fabric 10 as one embodiment of the method for producing the laminated nonwoven fabric of the present invention. As described above, the laminated nonwoven fabric 10 has the laminated structure 13 including the fiber layers of the thermoplastic fibers (the hydrophilic fibers 14 and the hydrophobic fibers 15), and the layers constituting the laminated structure 13 are welded to each other by the interlayer weld 16.

As shown in fig. 5, the method for producing the laminated nonwoven fabric 10 includes: a step of obtaining a laminate 10P by conveying a hydrophilic base nonwoven fabric 11P and depositing a hydrophobic fiber 15 obtained by spinning a resin on the base nonwoven fabric 11P being conveyed to obtain a laminate 10P; and an interlayer welding step of locally compressing and heating the laminate 10P in the thickness direction to form an interlayer welded portion 16. The base nonwoven fabric 11P has interfiber fusion portions 17 in which the constituent fibers (hydrophilic fibers 14) have a higher density than the peripheral portion and are fused to each other, and finally becomes the first layer 11 of the laminated nonwoven fabric 10 which is the production target of the present production method.

As shown in fig. 5, in the present manufacturing method, first, the base nonwoven fabric 11P wound in a roll is wound up and conveyed in one direction indicated by the reference MD by the conveyor belt 50, and in the course of the conveyance, the hydrophobic fibers 15 are spun from the spinneret of the spinneret 51 disposed above the conveyor belt 50 and directly deposited on the base nonwoven fabric 11P, thereby obtaining a laminate 10P. Then, the laminate 10P is continuously conveyed and supplied between the pair of emboss rollers 52 and 53, and the laminate 10P is subjected to hot embossing to form the interlayer welded portion 16 (interlayer welding step). The embossing roll 52 is disposed above the laminate 10P being conveyed, and is in contact with a pile (web) of the hydrophobic fibers 15 directly spun during the hot embossing process, and the embossing roll 53 is disposed below the laminate 10P being conveyed, and is in contact with the base nonwoven fabric 11P during the hot embossing process. While the outer peripheral surfaces of the embossing rollers 53 do not have irregularities on the outer peripheral surfaces of the both rollers 52 and 53 that come into contact with the laminate 10P as a workpiece, projections (not shown) are formed on the outer peripheral surfaces of the embossing rollers 52 in a pattern corresponding to the pattern of the interlayer fusion 16 in the laminated nonwoven fabric 10 as a production target. By compressing the laminate 10P in the thickness direction while heating the laminate to a temperature equal to or higher than the melting point of the thermoplastic fibers (hydrophilic fibers 14 and hydrophobic fibers 15) contained therein at the nip between the two rolls 52 and 53 having such a configuration, the laminate 10P is partially compressed from the accumulated side of the hydrophobic fibers 15 toward the base nonwoven fabric 11P by the convex portions of the embossing roll 52, and the interlayer fusion bonded portion 16 is formed at the compressed portion. By this interlayer fusion step, the deposition of the hydrophobic fibers 15 becomes a nonwoven fabric, and is integrated with the base nonwoven fabric 11P via the interlayer fusion portion 16. Through the above steps, a laminated nonwoven fabric 10 having a laminated structure 13 of a first layer 11 composed of a base nonwoven fabric 11P and a second layer 12 composed of a deposition (web) of hydrophobic fibers 15 is obtained. In the laminated nonwoven fabric 10 thus obtained, the interlayer weld 16 is recessed in a concave shape from the second surface 10b side to the first surface 10a side.

One of the main features of the present manufacturing method is that the hydrophobic fibers 15 are directly spun on the hydrophilic base nonwoven fabric 11P by a melt spinning method or the like to form a fiber web as a deposit thereof. In the present manufacturing method using the so-called direct spinning method, it is not necessary to stack the fibers (hydrophobic fibers 15) obtained by stretching or cutting the long fibers obtained by melt spinning on the base nonwoven fabric 11P after the long fibers are once taken up by a winder.

In the case of manufacturing a laminated nonwoven fabric such as the laminated nonwoven fabric 10, by using the direct spinning method as in the present manufacturing method, the grammage of the laminated nonwoven fabric can be reduced as compared with a method in which a plurality of nonwoven fabrics are integrated by the overlapped hot embossing, and in particular, the hydrophobic second layer 12 formed by the direct spinning can be easily thinned. As described above, the second layer 12 is preferable because it is easy to absorb liquid through the peripheral edge portion of the interlayer weld 16 and the vicinity thereof in the second surface 10b when the grammage is relatively small and the thickness is thin. Further, according to the present manufacturing method, since the spun hydrophobic fibers 15 are directly deposited on the hydrophilic base nonwoven fabric 11P to form the laminate 10P, the hydrophobic fibers 15 easily penetrate into the base nonwoven fabric 11P, and the adhesion between the first layer 11 and the second layer 12 is improved, so that when the interlayer fusion 16 and the periphery thereof in the second surface 10b are provided as the liquid introducing portion as described above, high liquid absorbability is exhibited, and further, the strength is strong, and a high-quality laminated nonwoven fabric 10 can be obtained.

In the case where the laminated nonwoven fabric of the present invention includes a plurality of second layers 12 laminated and the laminated structure 13 has a form of 3 or more layers, the hydrophobic fibers 15 may be stacked on the base nonwoven fabric 11P a plurality of times in the step of obtaining the laminate 10P. In this case, for example, in the manufacturing method shown in fig. 1, after a plurality of spinning nozzles 51 are intermittently arranged in the conveyance direction MD, the hydrophobic fibers 15 are sequentially spun from the respective spinning nozzles 51 and directly deposited on the base nonwoven fabric 11P.

The base nonwoven fabric 11P can be manufactured by a conventional method depending on the type of the base nonwoven fabric 11P. The base nonwoven fabric 11P is typically manufactured by the following steps: a step of depositing fibers obtained by spinning a resin to obtain a fiber web; and an interfiber welding step of locally compressing and heating the web in the thickness direction to form interfiber welded portions 17. For example, when the base nonwoven fabric 11P (first layer 11) is a spunbond nonwoven fabric, it is produced as follows. That is, first, a resin composition as a raw material of a nonwoven fabric is melted by an extruder or the like, and the molten resin is discharged from a spinneret of a spinneret to spin a long fiber. The spun long fibers are cooled by a cooling fluid, and then tensioned by drawing air to have a predetermined fineness, and collected directly on a collecting belt to be accumulated in a predetermined thickness. Next, the long fibers are subjected to a fusion-bonding treatment by hot embossing to form the interfiber fusion-bonded portion 17.

In the interfiber fusion step, the fiber web (sheet-like material that is not interfiber fused, precursor of the base nonwoven fabric 11P) is usually compressed and heated in the thickness direction from one surface side thereof to form interfiber fusion portions 17. When the laminated nonwoven fabric 10 is produced by the so-called direct spinning method using the base nonwoven fabric 11P having the interfiber fusion bonded portions 17 formed by compression from one surface side of the web as described above, the hydrophobic fibers 15 are deposited on the surface of the base nonwoven fabric 11P opposite to the compression surface (the surface on which the interfiber fusion bonded portions 17 are recessed). In the laminated nonwoven fabric 10 obtained in this way, the interfiber fusion bonded portions 17 are recessed in a concave shape from the first surface 10a side to the second surface 10b side.

The base nonwoven fabric 11P is hydrophilized in the laminated nonwoven fabric 10, which is the target product, at least at a point before the hydrophobic fibers 15 are directly deposited, to form the hydrophilic first layer 11. As described above, the hydrophilization treatment of the base nonwoven fabric 11P can be performed by a known hydrophilization treatment such as coating a hydrophilizing agent on the fibers or the fiber aggregate, doping a hydrophilizing agent into the fibers, or plasma treatment, and typically by doping a hydrophilizing agent or coating a hydrophilizing agent.

For example, in the case where the base nonwoven fabric 11P (first layer 11) is a spunbond nonwoven fabric, when hydrophilization treatment is performed by blending a hydrophilizing agent, a hydrophilizing agent master batch produced by adding a hydrophilizing agent to a thermoplastic resin to a predetermined concentration and then melt-kneading the mixture and a thermoplastic resin as a raw material of the nonwoven fabric are mixed at a predetermined ratio, and the mixture is melted by an extruder or the like, and a long fiber is spun out from a spinneret of a spinneret and then deposited to obtain a fiber web (precursor of the base nonwoven fabric 11P). The long fibers thus spun are hydrophilic fibers 14.

On the other hand, in the case where the hydrophilization treatment of the base nonwoven fabric 11P is performed by application of a hydrophilizing agent, the hydrophilizing agent is typically applied to a hydrophobic nonwoven fabric (precursor of the base nonwoven fabric 11P) composed of thermoplastic fibers (hydrophobic fibers) and having interfiber welds 17 obtained by a conventional method. When the laminated nonwoven fabric 10 is produced by the so-called direct spinning method using the base nonwoven fabric 11P to which the hydrophilizing agent has been applied by the application, the hydrophobic fibers 15 are deposited on the surface of the base nonwoven fabric 11P to which the hydrophilizing agent has been applied. In the laminated nonwoven fabric 10 thus obtained, the hydrophilizing agent is applied to the second face 10b side of the first layer 11 composed of the base nonwoven fabric 11P, and therefore, as described above, the first layer 11 has such a hydrophilicity gradient that the hydrophilicity on the first face 10a side is relatively low and the hydrophilicity on the second face 10b side is relatively high. That is, in the laminated nonwoven fabric 10 (laminated structure 13) obtained in this way, a hydrophilicity gradient is formed in which the hydrophilicity increases stepwise from the hydrophobic second layer 12 (second surface 10b) toward the inside in the thickness direction of the laminated structure 13, and therefore, further improvement in the liquid absorbency can be expected.

In the present manufacturing method, the laminate 10P (laminated nonwoven fabric 10) may be subjected to a calendering process immediately before or immediately after the start of the interlayer welding step, more specifically, immediately before or immediately after the hot embossing process using the pair of embossing rolls 52 and 53. It is known that the calendering process is a process of densifying a fiber aggregate such as a nonwoven fabric by applying heat and pressure to the fiber aggregate with a calender roll. By subjecting the laminate 10P to the calendering treatment before or after the interlayer welding step, the penetration of the "hydrophobic fibers 15" into the base nonwoven fabric 11P, which is an advantage of the above-described direct spinning method, is further promoted, and thus various properties such as liquid absorbency and strength of the laminated nonwoven fabric 10 can be further improved. The number, arrangement, and the like of the calender rolls used in the calendering are not particularly limited, and for example, a tandem type or an inclined type composed of 3 calender rolls, a tandem type, an inverted L type, a Z type or an inclined Z type composed of 4 calender rolls, and a Z type or an L type composed of 5 calender rolls can be used. The temperature of the rolling treatment is preferably not higher than the softening point of the constituent fibers of the laminate 10P (laminated nonwoven fabric 10) as the workpiece. When the calendering treatment is performed at the softening point or higher, the nonwoven fabric may become hard and the skin feel may be deteriorated.

In the present manufacturing method, the base nonwoven fabric 11P may be subjected to a calendering process before the hydrophobic fibers 15 are deposited on the base nonwoven fabric 11P, more specifically, before the base nonwoven fabric 11P being conveyed on the production line of the laminated nonwoven fabric 10 passes through the spinneret 51. Accordingly, the distance between the fibers of the base nonwoven fabric 11 is reduced, the capillary pressure is increased, and the liquid absorbency is increased, so that even if the hydrophobic second layer has a relatively large distance between the fibers and a low grammage, the second surface 10b side becomes dry after absorbing liquid. In short, the rolling treatment in the present manufacturing method may be performed immediately before the start of the interlayer welding step or immediately after the end of the interlayer welding step, before the hydrophobic fibers 15 are deposited on the base nonwoven fabric 11P, or both.

In addition, a rolling process may be employed in the process of manufacturing the base nonwoven fabric 11P. That is, the fiber web (sheet-like material that is not subjected to the interfiber welding, precursor of the base nonwoven fabric 11P) may be subjected to the calendering process immediately before or immediately after the interfiber welding process.

As described above, the laminated nonwoven fabric of the present invention includes a form in which an elastic member having a form such as a string form, a sheet form, an aggregate of elastic fibers (elastic fiber layer), or the like is interposed between the first layer and the second layer. In the case of manufacturing a laminated nonwoven fabric having such a structure that the elastic member is disposed between layers of the laminated structure, the elastic member may be disposed on the base nonwoven fabric 11P before the hydrophobic fibers 15 are deposited on the base nonwoven fabric 11P. The method of disposing the elastic member may be appropriately selected according to the form of the elastic member. For example, when an elastic fiber layer, which is an aggregate of elastic fibers, is disposed as the elastic member, the elastic fibers may be directly spun on the base nonwoven fabric 11P, similarly to the hydrophobic fibers 15.

Next, an absorbent article according to a preferred embodiment of the present invention will be described with reference to the drawings. The absorbent article of the present invention is characterized by having the laminated nonwoven fabric of the present invention. Specifically, as described above, the laminated nonwoven fabric of the present invention has a laminated structure of fibrous layers containing thermoplastic fibers, the laminated structure having a first surface as one surface of the laminated nonwoven fabric, the first surface being composed of a hydrophilic first layer containing hydrophilic fibers, and a second surface as the other surface, the second surface of the first layer being disposed on the second surface side thereof with a hydrophobic second layer containing hydrophobic fibers.

Fig. 6 to 8 show a pants-type disposable diaper 1 as an embodiment of the absorbent article of the present invention. The diaper 1 will be mainly described with respect to the components different from the laminated nonwoven fabric 10 which is the embodiment of the laminated nonwoven fabric, and the same components are denoted by the same reference numerals, and the description thereof will be omitted. The description of the laminated nonwoven fabric 10 is appropriately applied to the components not specifically described.

As shown in fig. 6 and 7, the diaper 1 has an abdominal region a and a back region B in the longitudinal direction X and a crotch region C located between these regions A, B, and has an absorbent body 23 spanning the abdominal region a and the back region B, and has an abdominal waist panel FA and a back waist panel FB extending in the transverse direction Y outside the front and

back end portions

23A, 23B of the absorbent body 23 in the longitudinal direction X. Here, the abdomen-side region a is a region disposed on the abdomen side of the wearer when the absorbent article such as a disposable diaper is worn, and the back-side region B is a region disposed on the back side of the wearer when the absorbent article such as a disposable diaper is worn. The abdominal region a and the back region B are waist portions corresponding to the waist of the wearer when the diaper 1 is worn.

As shown in fig. 7, the abdomen-side waist panel FA is a region in which a region extending in the lateral direction Y from the end edge of the front end portion 23A on the abdomen-side region a side in the longitudinal direction X of the absorbent body 23 to the outside in the longitudinal direction X and a region extending in the lateral direction Y from the front end portion 23A on the abdomen-side region a side in the longitudinal direction X of the absorbent body 23 are joined together. The back-side waist panel FB refers to a region that joins a region that is located outside the longitudinal direction X from the end edge of the rear end portion 23B on the back-side region B side in the longitudinal direction X of the absorbent body 23 and extends in the lateral direction Y and a region that extends in the lateral direction Y from the rear end portion 23B on the back-side region B side in the longitudinal direction X of the absorbent body 23.

As shown in fig. 6 and 7, the diaper 1 includes an absorbent main body 2 and an outer cover 3 disposed on the non-skin contact surface side of the absorbent main body 2 and fixing the absorbent main body 2, and the outer cover 3 includes a front waist panel FA and a back waist panel FB extending in the transverse direction Y and located outside the front and

rear end portions

23A, 23B in the longitudinal direction X of the absorbent body 23 constituting the absorbent main body 2. In the diaper 1, the stretchable regions (the waist stretch section G1 and the lower waistline stretch section G2) are formed in the abdomen-side waist panel FA and the back-side waist panel FB.

As shown in fig. 7, the diaper 1 is a so-called pant-type disposable diaper (see fig. 6) in which left and right side edge portions 3a1, 3a1 of a front region a of an outer package 3 and left and right side edge portions 3B1, 3B1 of a back region B of the outer package 3 are joined to each other to form a pair of side seals S, S, a waist opening WO, and a pair of leg openings LO, LO. In the unfolded and extended state shown in the plan view of fig. 7, the outer package 3 of the diaper 1 is preferably divided into a ventral region a disposed on the ventral side of the wearer when worn, a back-side region B disposed on the back side of the wearer when worn, and a crotch region C between the ventral region a and the back-side region B. The developed and extended state of the diaper 1 here means a state in which the diaper 1 is developed by tearing the side seals S, the elastic members of the respective portions are extended, and the developed diaper 1 is extended to a design size (the same size as when it is developed in a flat shape with the influence of the elastic members completely eliminated), as shown in fig. 7.

In the present specification, the "skin contact surface" refers to a surface of the diaper 1 or a component thereof (for example, the absorbent body 2) that faces the skin side of the wearer when worn, and the "non-skin contact surface" refers to a surface of the diaper 1 or a component thereof that faces the side opposite to the skin side of the wearer (the garment side) when worn. In the diaper 1, the longitudinal direction X is a direction corresponding to a direction extending from the abdomen side to the back side of the wearer through the crotch portion, and is a direction from the abdomen-side region a to the back-side region B in a state where the diaper 1 is spread out flat and stretched. The lateral direction Y is a direction perpendicular to the longitudinal direction X, and is a width direction of the diaper 1 in a state of being developed into a plane and extended. Further, the diaper 1 has a left-right symmetrical shape with respect to a longitudinal centerline CL1 extending in the longitudinal direction X as shown in fig. 7. CL2 in fig. 7 is a transverse centerline extending in the transverse direction Y and bisecting the diaper 1, and is orthogonal to the longitudinal centerline CL 1.

In the diaper 1, the absorbent body 2 has a longitudinal shape in which the longitudinal direction X is relatively long in the unfolded and extended state of the diaper 1, as shown in fig. 7. The absorbent main body 2 includes a liquid-permeable front surface sheet 21 forming a skin contact surface, a liquid-impermeable back surface sheet 22 forming a non-skin contact surface (including water repellency), and a liquid-retaining absorbent body 23 disposed between the two

sheets

21, 22. In addition, as shown in fig. 7,

leakage preventing cuffs

24 and 24 having elastic members arranged in a state of being stretched in the longitudinal direction X are provided on both side portions of the absorbent main body 2 in the longitudinal direction X (longitudinal direction). Specifically, the leakage preventing cuffs 24 are made of a liquid-impermeable or water-repellent and air-permeable material, and the elastic member 25 for forming the leakage preventing cuffs is disposed in the vicinity of the free end portions of the leakage preventing cuffs 24 so as to extend in the longitudinal direction X. When the diaper is worn, the leakage-barrier cuff-forming elastic member 25 contracts to raise the free end portion side of the leakage-barrier cuff 24 and prevent the body fluid from flowing out in the lateral direction Y.

The absorbent body 2 configured as described above has a longitudinal direction that coincides with the longitudinal direction X of the diaper 1 in an unfolded and extended state, and is joined to the central portion of the outer cover 3 by the body-fixing adhesive, as shown in fig. 7. In this way, the outer cover 3 is disposed on the non-skin contact surface side of the back sheet 22 constituting the absorbent main body 2 in the thickness direction of the disposable diaper 1, and is fixed by adhesion. Therefore, in the diaper 1, the absorbent body 23 constituting the absorbent main body 2 is disposed so as to straddle the abdomen-side region a and the back-side region B.

In the diaper 1, as shown in fig. 7, the outer cover 3 has an abdomen-side waist panel FA and a back-side waist panel FB which are positioned outside the front and

rear end portions

23A, 23B of the absorbent body 23 in the longitudinal direction X and extend in the transverse direction Y. As shown in fig. 6 to 8, the outer cover 3 includes an outer sheet 6 forming the outer surface of the diaper 1 on the non-skin contact surface side, and an inner sheet 3i disposed on the skin contact surface side of the outer sheet 6, and the outer sheet 6 includes a folded portion 6R formed by folding back an extended portion extending from the front and rear end portions in the longitudinal direction X of the inner sheet 3i toward the skin contact surface side of the inner sheet 3 i. As shown in fig. 7, the folded back portion 6R of the outer sheet 6 is formed in a rectangular shape long in the lateral direction Y. The front and

rear end portions

23A, 23B of the absorbent main body 2 are respectively covered with the folded-back portions 6R.

As described above, the diaper 1 has the abdomen-side region a and the back-side region B as waist portions corresponding to the waist circumference of the wearer when worn, and as shown in fig. 7, at least the waist stretchable component G1 and the lower waist stretchable component G2 are formed as stretchable regions in both regions A, B, and further, leg stretchable components G3 may be formed. That is, the exterior body 3 has a plurality of elastic members 71 arranged at intervals in the longitudinal direction X in a state of being stretched in the lateral direction Y between the outer layer sheet 6 and the inner layer sheet 3i constituting the exterior body 3 in the two regions A, B, and thereby the waist stretchable portion G1 and the lower waistline stretchable portion G2 are formed as stretchable regions having stretchability in the lateral direction Y in the two regions A, B. The exterior body 3 further includes a plurality of leg elastic members 72, and the plurality of leg elastic members 72 are disposed between the outer sheet 6 and the inner sheet 3i in a state of being stretched in a predetermined direction from each of the two regions A, B to the crotch region C, whereby the leg stretch units G3 can be formed as stretch regions in these regions A, B, C.

In the diaper 1, as shown in fig. 6 and 7, the waist stretch units G1 are formed in the end flaps located more outward in the longitudinal direction X (on the side opposite to the side of the transverse centerline CL 2) than the end edges of the front and

rear end portions

23A, 23B in the longitudinal direction X of the absorbent body 23 constituting the absorbent main body 2. In the diaper 1, the waist lower stretch units G2 are formed on the side flaps between the lower ends of the waist stretch units G1 on the side of the transverse centerline CL2 and the lower ends of the side seals S in the longitudinal direction X. The back-side waist panel FB and the abdomen-side waist panel FA are also regions in which the end panel (waist stretch panel G1) and a part of the side panel (waist lower stretch panel G2) are combined. In addition, in the diaper 1, as shown in fig. 6 and 7, the leg stretch units G3 are formed at the peripheral edge of the leg opening LO.

As shown in fig. 6 to 8, the diaper 1 has a sweat-absorbent sheet 10 (see fig. 1) capable of absorbing sweat, and the sweat-absorbent sheet 10 is a laminated nonwoven fabric 10 which is an embodiment of the laminated nonwoven fabric of the present invention described above. The sweat-absorbent sheet 10 is disposed so that the second surface 10b (the outer surface of the hydrophobic second layer 12) faces the skin of the wearer.

In the diaper 1, the sweat-absorbent sheet 10 is disposed in the stretchable region of the waist portion mainly for the purpose of absorbing sweat around the waist of the wearer. That is, as shown in fig. 7, the sweat-absorbent sheet 10 has a shape elongated in one direction in a plan view, specifically, a rectangular shape (band shape), and is disposed over the entire length in the lateral direction Y of each of the abdomen-side region a and the back-side region B as the waist region, and at least over the waist stretchable section G1 and the under-waist stretchable section G2, with the longitudinal direction thereof being aligned with the lateral direction Y. Specifically, the sweat-absorbent sheet 10 is joined to the skin contact surface of the folded portion 6R of the outer-layer sheet 6 by known joining means such as an adhesive, heat sealing, ultrasonic sealing, or the like. Since the folded-back portion 6R is disposed closer to the skin of the wearer than the absorbent body 23 when the diaper 1 is worn (see fig. 8), the sweat-absorbent sheet 10 disposed on the skin contact surface of the folded-back portion 6R is disposed closer to the skin of the wearer than the absorbent body 23 when the diaper 1 is worn, and can contact the skin of the wearer.

In the diaper 1 having the above-described configuration, the sweat-absorbent sheet 10 (laminated nonwoven fabric 10) having a sweat-absorbent function is disposed closest to the skin of the wearer of the diaper 1 on the skin contact surface side of each of the abdomen-side region a and the back-side region B which are the waist regions, and the region in which the sweat-absorbent sheet 10 is disposed is an extensible region having extensibility in the lateral direction Y including the waist extensible portion G1 and the lower waist extensible portion G2, so that the hydrophobic second surface 10B (see fig. 1) of the sweat-absorbent sheet 10 fits well to the skin of the wearer by fastening due to the contractive force of the extensible region when the diaper 1 is worn, and sweat emitted from the skin can be absorbed and evaporated quickly.

In the diaper 1, since the sweat-absorbent sheet 10 (laminated nonwoven fabric 10) is disposed in the stretchable region as described above, the sweat-absorbent sheet 10 is also preferably stretchable in the same direction as the stretchable region, i.e., in the lateral direction Y, from the viewpoint of improving the fit to the skin of the wearer. From such a viewpoint, it is preferable that an elastic member (stretchable member) having stretchability in the transverse direction Y is disposed between the first layer 11 and the second layer 12 in the sweat-absorbent sheet 10. The elastic member is as described above.

The materials for forming the respective parts of the diaper 1 are explained, and various materials and the like conventionally used for absorbent articles such as disposable diapers can be used without particular limitation as the front sheet 21, back sheet 22, absorber 23, leakage preventive cuffs 24 and the like constituting the absorbent main body 2. For example, a single-layer or multi-layer nonwoven fabric, an apertured film, or the like can be used as the front sheet 21. As the back sheet 22, a moisture-permeable resin film or the like can be used. As the absorbent body 23, an absorbent body in which an absorbent core made of particles of an absorbent polymer and a fibrous material is covered with tissue paper can be used. Further, as the leak-proof cuff 24, a water repellent nonwoven fabric having a single-layer or multi-layer structure or the like can be used. Examples of the elastic members (the elastic member 25 for forming the leakproof cuff, the elastic member 71, the leg elastic member 72, and the like) include synthetic rubbers such as styrene-butadiene, isoprene, and chloroprene rubber, natural rubbers, EVA, stretchable polyolefins, and polyurethane. As the form of the elastic member, a linear form (such as a linear rubber) or a belt form (such as a rubber strip) having a rectangular, square, circular, elliptical, or polygonal cross section can be preferably used. As a joining means for joining the components of the diaper 1, various adhesives such as hot melt adhesives conventionally used for such absorbent articles can be used.

The present invention has been described above based on embodiments thereof, but the present invention is not limited to the above embodiments and can be appropriately modified.

For example, in the diaper 1, the laminated nonwoven fabric 10 which is an embodiment of the laminated nonwoven fabric of the present invention is used as the sweat-absorbent sheet 10, but the absorbent article of the present invention may be provided with the laminated nonwoven fabric of the present invention disposed so that the second surface (the hydrophobic surface having the interlayer weld) faces the skin side of the wearer, the laminated nonwoven fabric of the present invention may be used as a component other than the sweat-absorbent sheet, and when used as the sweat-absorbent sheet, the disposition position is not limited to the disposition position of the sweat-absorbent sheet 10 in the diaper 1.

Another application of the laminated nonwoven fabric of the present invention as a component of an absorbent article is a topsheet disposed closer to the skin of the wearer than the absorbent body. That is, for example, in the diaper 1, the laminated nonwoven fabric 10 is used as the topsheet 21.

In the outer package 3 of the diaper 1, as shown in fig. 7, the elastic member 71 is disposed between the outer sheet 6 and the inner sheet 3i, but the elastic member 71 may not be disposed. When the stretchable region is formed without disposing the elastic member 71, a stretchable nonwoven fabric having stretchability in the lateral direction Y may be used as a component of the outer package 3.

In the diaper 1, as shown in fig. 7, the outer cover 3 has a continuous shape extending over the front side region a, the crotch region C, and the back side region B, but instead, the outer cover 3 may have a divided shape divided into the front side outer cover, the back side outer cover, and the crotch side outer cover as separate members.

The absorbent article of the present invention is not limited to the pants-type disposable diaper such as the diaper 1 described above, and can be applied to all articles used for absorbing body fluids, for example, an open-type disposable diaper and a sanitary napkin.

Further, the sweat-absorbent sheet of the present invention is not limited to the use in the absorbent article described above, and may be applied to articles other than absorbent articles. For example, as the sheet itself used by the user for wiping off sweat, the sweat-absorbent sheet of the present invention can be used. In addition, the sweat absorbing sheet of the present invention can be applied to shoe pads, underarm sweat pads, eye patches, face masks, and the like, and sweat emitted from the sole, underarm, and face can be rapidly absorbed and evaporated by being disposed toward the skin of the wearer.

The following remarks are also disclosed with respect to the above-described embodiments of the present invention.

< 1 > a laminated nonwoven fabric having a laminated structure of fiber layers containing thermoplastic fibers, wherein,

the laminated structure has a first surface as one surface of the laminated nonwoven fabric and a second surface as the other surface, the first surface being composed of a hydrophilic first layer, a hydrophobic second layer being disposed on the second surface side of the first layer,

the laminated structure has an interlayer fusion part which has a thickness smaller than that of the peripheral part and is formed by fusing the layers of the laminated structure to each other,

the first layer has inter-fiber fusion parts which are smaller in thickness than the peripheral parts and in which the constituent fibers of the first layer are fused to each other, in addition to the interlayer fusion parts,

when the ratio of the total area of the interlayer fusion and the inter-fiber fusion in the first surface to the area of the second surface is referred to as the fusion area ratio of each surface, the fusion area ratio of the first surface is larger than the fusion area ratio of the second surface.

< 2 > the laminated nonwoven fabric according to the above < 1 >, wherein,

the ratio of the area ratio of the welding part of the first surface to the area ratio of the welding part of the second surface is 1.3-3.0 when expressed by former/latter.

< 3 > the laminated nonwoven fabric according to < 1 > or < 2 > above, wherein,

the arrangement pattern of the interlayer fusion part and the interfiber fusion part, the planar shape of the single fusion part, the area of the single fusion part, the distance between the fusion parts, and the pitch are different.

< 4 > the laminated nonwoven fabric according to any one of the above < 1 > -3 >, wherein,

the interlayer fusion part is recessed in a concave shape from the second surface side to the first surface side.

< 5 > the laminated nonwoven fabric according to any one of the above < 1 > -4 >, wherein,

the inter-fiber fusion-bonded portion is recessed in a concave shape from the first surface side toward the second surface side.

< 6 > the laminated nonwoven fabric according to any one of the above < 1 > -5 >, wherein,

the second surface has an interlayer fusion part distribution area where a plurality of interlayer fusion parts are distributed, and when a circle with a radius of 2mm is virtually provided at any position of the interlayer fusion part distribution area, part or all of at least 1 interlayer fusion part is contained in the virtual circle.

< 7 > the laminated nonwoven fabric according to any one of the above < 1 > -6 >, wherein,

the ratio of the area of the interlayer weld to the area of the second surface is 15% or less.

< 8 > the laminated nonwoven fabric according to any one of the above < 1 > -7 >, wherein,

the pitch of the interlayer fusion is shorter than that of the interfiber fusion.

< 9 > the laminated nonwoven fabric according to any one of the above < 1 > -to < 8 >, wherein,

1 of the interlayer fusion parts has an area of 0.3mm on the second surface²The area of the first surface is smaller than 1 inter-fiber welded portion.

< 10 > the laminated nonwoven fabric according to any one of the above < 1 > -to < 9 >, wherein,

the ratio of the area of 1 interlayer welded part on the second surface to the area of 1 interfiber welded part on the first surface is 0.25 to 0.8, expressed as the former/the latter.

< 11 > the laminated nonwoven fabric according to any one of the above < 1 > -to < 10 >, wherein,

the combined grammage of the first layer and the second layer is 8g/m²Above 30g/m²The following.

< 12 > the laminated nonwoven fabric according to any one of the above < 1 > -11 >, wherein,

the gram weight of the first layer is 5g/m²Above 25g/m²The following.

< 13 > the laminated nonwoven fabric according to any one of the above < 1 > -to < 12 >, wherein,

the first layer has a higher degree of hydrophilicity on the second surface side than on the first surface side.

< 14 > the laminated nonwoven fabric according to any one of the above < 1 > -to < 13 >, wherein,

the first layer contains a constituent fiber having a hydrophilizing agent adhered to the surface thereof.

< 15 > the laminated nonwoven fabric according to any one of the above < 1 > -14 >, wherein,

in the first layer, the hydrophilizing agent adhering to the surface of the constituent fibers is more biased toward the second surface side than toward the first surface side.

< 16 > the laminated nonwoven fabric according to any one of the above < 1 > -15 >, wherein,

the first layer is a hydrophilic nonwoven fabric containing constituent fibers doped with a hydrophilizing agent.

< 17 > the laminated nonwoven fabric according to any one of the above < 1 > -16 >, wherein,

the gram weight of the second layer is 3g/m²Above 15g/m²The following.

< 18 > the laminated nonwoven fabric according to any one of the above < 1 > -to < 17 >, wherein,

the distance between the fibers constituting the first layer is shorter than that of the second layer.

< 19 > the laminated nonwoven fabric according to any one of the above < 1 > -18 >, wherein,

the first layer has a greater amount of constituent fibers per unit area than the second layer.

< 20 > the laminated nonwoven fabric according to any one of the above < 1 > -19 >, wherein,

the fibers constituting the first layer have a smaller diameter than the fibers constituting the second layer.

< 21 > the laminated nonwoven fabric according to any one of the above < 1 > -20 >, wherein,

a long fiber layer containing long fibers is disposed on the second surface side of the second layer.

< 22 > the laminated nonwoven fabric according to the above < 21 >, wherein,

the long fiber layer has a hydrophilic layer containing a constituent fiber doped with a hydrophilizing agent.

< 23 > the laminated nonwoven fabric according to any one of the above < 1 > -22 >, wherein,

an elastic member is present between the first layer and the second layer.

< 24 > a method for producing a laminated nonwoven fabric having a laminated structure of fiber layers containing thermoplastic fibers, the layers constituting the laminated structure being fused to each other by interlayer fusion, the method comprising:

a step of obtaining a laminate by conveying a hydrophilic base nonwoven fabric having a higher density than the peripheral portion and constituting an interfiber fusion portion in which fibers are fused to each other, and stacking a hydrophobic fiber obtained by spinning a resin on the base nonwoven fabric being conveyed; and

and an interlayer welding step of locally compressing and heating the laminate in the thickness direction to form the interlayer weld.

< 25 > the method for producing a laminated nonwoven fabric according to the above < 24 >, wherein,

immediately before or immediately after the interlayer welding step, the laminate is subjected to a rolling treatment.

< 26 > the method for producing a laminated nonwoven fabric according to the above < 24 > or < 25 >, wherein,

the base nonwoven fabric is produced by the following steps: a step of depositing hydrophilic fibers obtained by spinning a resin to obtain a fiber web; and an interfiber fusion step of locally compressing and heating the fiber web in the thickness direction to form the interfiber fusion parts,

immediately before or immediately after the inter-fiber welding step, the fiber web is subjected to a calendering process.

< 27 > the method of producing a laminated nonwoven fabric according to any one of the above < 24 > -26 >, wherein,

before the hydrophobic fibers are deposited on the base nonwoven fabric, the base nonwoven fabric is subjected to a calendering treatment.

< 28 > the method of producing a laminated nonwoven fabric according to any one of < 24 > to < 27 > above, wherein,

the inter-fiber fusion-bonded part of the base nonwoven fabric is formed by compressing the base nonwoven fabric in the thickness direction from one surface side, and the hydrophobic fiber is deposited on the surface opposite to the compression surface.

< 29 > the method of producing a laminated nonwoven fabric according to any one of the above < 24 > -28 >, wherein,

a hydrophilizing agent is applied to one surface of the base nonwoven fabric, and the hydrophobic fibers are deposited on the surface to which the hydrophilizing agent is applied.

< 30 > the method of producing a laminated nonwoven fabric according to any one of the above < 24 > -29 >, wherein,

before the hydrophobic fibers are deposited on the base nonwoven fabric, an elastic member is disposed on the base nonwoven fabric.

< 31 > the method of producing a laminated nonwoven fabric according to any one of the above < 24 > -30 >, wherein,

in the step of obtaining the laminate, the hydrophobic fibers are stacked on the base nonwoven fabric a plurality of times.

< 32 > an absorbent article comprising a laminated nonwoven fabric having a laminated construction of fiber layers containing thermoplastic fibers, wherein,

when the ratio of the total area of the interlayer fusion and the interfiber fusion in the first surface to the area of the second surface is referred to as the fusion area ratio of the respective surfaces, the fusion area ratio of the first surface is larger than that of the second surface,

the laminated nonwoven fabric is disposed so that the second surface faces the skin of the wearer.

< 33 > the absorbent article according to < 32 > above, wherein,

an absorbent body having liquid retention properties, wherein the laminated nonwoven fabric is disposed at a position closer to the skin of the wearer than the absorbent body.

< 34 > the absorbent article according to < 32 > or < 33 > above, wherein,

the absorbent article has a waist portion corresponding to the waist of the wearer, and the laminated nonwoven fabric is disposed in the waist portion.

< 35 > the absorbent article according to < 34 > above, wherein,

the waist portion has an extensible region, and the laminated nonwoven fabric is disposed in the extensible region.

< 36 > the absorbent article according to < 35 > above, wherein,

the elastic member is present between the first layer and the second layer in the laminated nonwoven fabric.

< 37 > the absorbent article according to < 32 > above, wherein,

the laminated nonwoven fabric has a sweat-absorbent sheet capable of absorbing sweat, and the sweat-absorbent sheet is the laminated nonwoven fabric.

< 38 > a sweat-absorbent sheet having a laminated structure of fiber layers containing thermoplastic fibers, having a first face and a second face on the opposite side thereof, used in such a manner that the second face is directed toward the skin side of the wearer, wherein,

the first surface is composed of a hydrophilic first layer, a hydrophobic second layer is disposed on the second surface side of the first layer,

when the ratio of the total area of the interlayer fusion and the interfiber fusion in the first surface to the area of the second surface is referred to as the fusion area ratio of the respective surfaces, the fusion area ratio of the first surface is larger than that of the second surface.

< 39 > use of the laminated nonwoven fabric described in any one of the above < 1 > -23 > for absorbing sweat.

< 40 > a method for absorbing sweat using the laminated nonwoven fabric described in any one of the above < 1 > -23 >.

Industrial applicability of the invention

According to the present invention, a laminated nonwoven fabric excellent in absorption performance of body fluid such as sweat or urine, a method for producing the same, an absorbent article, and a sweat-absorbent sheet can be provided.

Claims

1. An absorbent article having a waist portion corresponding to a waist of a wearer, in which a laminated nonwoven fabric having a laminated structure of fiber layers containing thermoplastic fibers is disposed, the absorbent article being characterized in that:

the laminated structure has a first surface as one surface of the laminated nonwoven fabric and a second surface as the other surface, the first surface is composed of a hydrophilic first layer, a hydrophobic second layer is arranged on the second surface side of the first layer, and the second surface is hydrophobic,

the first layer has inter-fiber fusion parts, which have a thickness smaller than that of the peripheral part and in which the constituent fibers of the first layer are fused to each other, in addition to the interlayer fusion parts,

when the ratio of the total area of the interlayer fusion and the interfiber fusion in the first and second surfaces to the area of the surface is referred to as the fusion area ratio of the surfaces, the fusion area ratio of the first surface is greater than the fusion area ratio of the second surface,

2. The absorbent article of claim 1, wherein:

and an absorbent body having liquid retention properties, wherein the laminated nonwoven fabric is disposed at a position closer to the skin of the wearer than the absorbent body.

3. The absorbent article according to claim 1 or 2, characterized in that:

the second layer is a long fiber nonwoven fabric.

4. The absorbent article according to claim 1 or 2, characterized in that:

the waist portion has a stretchable region, and the laminated nonwoven fabric is disposed in the stretchable region.

5. The absorbent article of claim 4, wherein:

an elastic member is present between the first layer and the second layer in the laminated nonwoven fabric.

6. The absorbent article according to claim 1 or 2, characterized in that:

has a sweat-absorbent sheet capable of absorbing sweat, the sweat-absorbent sheet being the laminated nonwoven fabric.

7. The absorbent article according to claim 1 or 2, characterized in that:

the ratio of the area ratio of the welding part of the first surface to the area ratio of the welding part of the second surface is 1.3-3.0 when the former/the latter is expressed.

8. The absorbent article according to claim 1 or 2, characterized in that:

at least two of the arrangement pattern of the interlayer fusion part and the interfiber fusion part, the planar shape of the single fusion part, the area of the single fusion part, the distance between the fusion parts and the pitch are different.

9. The absorbent article according to claim 1 or 2, characterized in that:

10. The absorbent article according to claim 1 or 2, characterized in that:

the inter-fiber fusion part is recessed in a concave shape from the first surface side to the second surface side.

11. The absorbent article according to claim 1 or 2, characterized in that: the second surface has an interlayer fusion part scattered arrangement region where a plurality of interlayer fusion parts are scattered, and when a circle having a radius of 2mm is virtually provided at an arbitrary position in the interlayer fusion part scattered arrangement region, a part or all of at least 1 interlayer fusion part is included in the virtual circle.

12. The absorbent article according to claim 1 or 2, characterized in that: a ratio of an area of the interlayer weld to an area of the second surface is 15% or less.

13. The absorbent article according to claim 1 or 2, characterized in that: the pitch of the inter-layer weld is shorter than the pitch of the inter-fiber weld.

14. The absorbent article according to claim 1 or 2, characterized in that: 1 of the interlayer fusion parts has an area of 0.3mm on the second surface²The area of the first surface is smaller than 1 fiber-to-fiber fusion part.

15. The absorbent article according to claim 1 or 2, characterized in that: the ratio of the area of 1 interlayer weld on the second surface to the area of 1 fiber weld on the first surface is 0.25 to 0.8, expressed as the former/the latter.

16. The absorbent article according to claim 1 or 2, characterized in that: the combined grammage of the first and second layers is 8g/m²Above 30g/m²The following.

17. The absorbent article according to claim 1 or 2, characterized in that: the grammage of the first layer is 5g/m²Above 25g/m²The following.

18. The absorbent article according to claim 1 or 2, characterized in that: in the first layer, the second surface side has higher hydrophilicity than the first surface side.

19. The absorbent article according to claim 1 or 2, characterized in that: the first layer contains a constituent fiber having a hydrophilizing agent attached to the surface thereof.

20. The absorbent article according to claim 1 or 2, characterized in that: in the first layer, the hydrophilizing agent adhering to the surface of the constituent fibers is more biased toward the second surface side than toward the first surface side.

21. The absorbent article according to claim 1 or 2, characterized in that: the first layer is a hydrophilic nonwoven fabric containing constituent fibers doped with a hydrophilizing agent.

22. The absorbent article according to claim 1 or 2, characterized in that: the gram weight of the second layer is 3g/m²Above 15g/m²The following.

23. The absorbent article according to claim 1 or 2, characterized in that: the inter-fiber distance of the constituent fibers of the first layer is shorter than the inter-fiber distance of the constituent fibers of the second layer.

24. The absorbent article according to claim 1 or 2, characterized in that: the amount of fibers per unit area of the constituent fibers of the first layer is greater than the amount of fibers per unit area of the constituent fibers of the second layer.

25. The absorbent article according to claim 1 or 2, characterized in that: the fiber diameter of the constituent fibers of the first layer is smaller than the fiber diameter of the constituent fibers of the second layer.

26. The absorbent article according to claim 1 or 2, characterized in that: a long fiber layer containing long fibers is disposed on the second surface side of the second layer.

27. The absorbent article of claim 26, wherein:

the long fiber layer has a hydrophilic layer containing constituent fibers doped with a hydrophilizing agent.