RU2735657C1 - Absorbent product - Google Patents

Abstract

FIELD: satisfaction of human vital needs.

SUBSTANCE: multilayer non-woven fabric (10) of absorbent product (1) according to present invention includes hydrophilic first layer (11) and hydrophobic second layer (12). First layer (11) comprises fibers that cannot be fused. Second layer (12) is formed mainly by fibers which are fastened by fusion, which are long fibers. Multilayer nonwoven material (10) in some parts on a plan view of interlayer connected parts (16), in which layers forming multilayer structure (13) are connected together, wherein each of the interlayered connected parts has a smaller thickness than the peripheral part. Section including the interlayer connected part (16) is recessed in the form of a recess from the side of second surface (10b) towards the side of first surface (10a). In the interlayer connected part (16), first layer (11) fibers are stored in the form of fibers and second layer (12) components fibers (15) are melted, and part of molten resin component passes between constituent fibers of first layer (11) and hardens. Multilayer nonwoven material (10) is located in the part of absorbent product (1) intended for waist / hip so that second surface (10b) faces the side of the skin of the carrier.

EFFECT: absorbent article is described.

17 cl, 10 dwg

Description

The technical field to which the invention relates

[0001]

The present invention relates to an absorbent article and a sweat-absorbent sheet using a multilayer nonwoven fabric having a multilayer structure in which a plurality of nonwoven fabrics are layered on top of each other.

Prior art

[0002]

Conventional absorbent articles such as disposable diapers and sanitary napkins use constituent elements such as a nonwoven material having a multilayer structure including two or more layers, or a nonwoven material having a surface with ridges and depressions. For example, Patent Document 1 discloses a configuration in which a sweat-absorbent sheet capable of absorbing sweat of a wearer is disposed in a portion of the disposable diaper that contacts the skin of the wearer. This document also discloses the use, as a sweat-absorbent sheet, of a multilayer nonwoven fabric having a multilayer structure including a hydrophobic nonwoven fabric and a hydrophilic nonwoven fabric, the two nonwoven fabrics being bonded together through a plurality of fusion bonded portions that are buried in and it is disclosed that the multilayer nonwoven material is positioned such that the hydrophobic nonwoven material faces the skin side of the wearer.

[0003]

In Patent Document 2, as a multilayer nonwoven fabric suitable as a constituent member of an absorbent article, a nonwoven sheet is disclosed that is permeable to water in one direction, which is permeable to liquids in a direction from one surface, but is impervious to liquids in the opposite direction. In this document, as an embodiment of the one-way water permeable nonwoven sheet, there is also disclosed a sheet in which at least one layer is a hydrophilic nonwoven fabric and the remainder is a non-hydrophilic nonwoven fabric. Patent Document 2 also discloses a method of stacking a plurality of nonwoven fabrics on top of each other and performing fusion bonding by means of a hot embossing roller as a method for manufacturing a multilayer nonwoven fabric. In this document, as another manufacturing method, a method is disclosed in which first long fibers of a given fineness are applied directly to a spun-bonded nonwoven fabric and then entanglement is performed by means such as needling, water-jetting, ultrasonic welding, etc., or performing Fusion bonding with a hot stamping roller.

List of links

Patent documents

[0004]

Patent Document 1: JP 2004-298467 A

Patent Document 2: JP 2006-51649 A

The essence of the invention

[0005]

The present invention relates to an absorbent article including a multilayer nonwoven fabric having a multilayer structure in which a plurality of fibrous layers are superimposed on each other. The multilayer nonwoven fabric has a first surface defining one surface and a second surface defining another surface, and the multilayer nonwoven fabric includes a hydrophilic first layer defining a first surface and a hydrophobic second layer located on the second surface side of the first layer. The first layer contains fibers that cannot be fused together. The second layer is mainly composed of fusion-bonding fibers, which are long fibers. The multilayer nonwoven fabric includes, in some portions in a plan view of the multilayer nonwoven fabric, interlayer bonded portions in which the layers forming the multilayer structure are bonded together, each of the interlayer bonded portions being thinner than the peripheral portion. The part including the interlayer bonded part is recessed from the second surface side towards the first surface side. The constituent fibers of the first layer are stored as fibers in the interlayer bonded portion. The constituent fibers of the second layer in the interlayer bonded portion are melted, and a portion of the molten resin constituent passes between the constituent fibers of the first layer and solidifies. The multilayer nonwoven fabric is positioned with the second surface facing the skin side of the wearer. The absorbent article includes a waist / hip portion corresponding to the waist / hips of the wearer, and a multilayer nonwoven fabric is disposed in the waist / hip portion.

[0006]

The present invention also relates to a absorbent sheet having a multilayer structure in which a plurality of fibrous layers are superimposed on one another. The absorbent sheet has a first surface and a second surface located on the side opposite to the first surface, and the absorbent sheet is used with the second surface facing the skin side of the wearer. The sweatable sheet includes a hydrophilic first layer defining a first surface and a hydrophobic second layer located on the second surface side of the first layer. The first layer contains fibers that cannot be fused together. The second layer is mainly composed of fusion-bonding fibers, which are long fibers. The sweatable sheet includes, in some portions in a plan view of the multilayer nonwoven fabric, interlayer bonded portions in which the layers forming the multilayer structure are bonded together, each of the interlayer bonded portions having a smaller thickness than the peripheral portion. The portion including the interlayer bonded portion is recessed from the second surface side towards the first surface side. The constituent fibers of the first layer are stored as fibers in the interlayer bonded portion. The constituent fibers of the second layer in the interlayer bonded portion are melted, and a portion of the molten resin constituent passes between the constituent fibers of the first layer and solidifies. The sweat sheet is able to absorb perspiration.

Brief Description of Drawings

[0007]

[Fig. 1] FIG. 1 is a sectional view schematically illustrating a section along a thickness direction of a multilayer nonwoven fabric according to an embodiment of the present invention.

[Fig. 2] FIG. 2 is an enlarged view of the interlayer bonded portion in the multilayer nonwoven fabric illustrated in FIG. 1.

[Fig. 3] FIG. 3 (a) -3 (d) are schematic views schematically illustrating configurations of interlayer bonded portions according to the present invention.

[Fig. 4] FIG. 4 is a schematic diagram of an embodiment of a method for manufacturing a multilayer nonwoven fabric according to the present invention.

[Fig. 5] FIG. 5 is a schematic perspective view of a pull-on disposable diaper that is an embodiment of an absorbent article of the present invention.

[Fig. 6] FIG. 6 is an exploded plan view schematically illustrating the skin-facing side (inner-surface side) of the diaper of FIG. 5 in a straightened and stretched state.

[Fig. 7] FIG. 7 is a longitudinal section, schematically illustrating a section taken along the line I-I in FIG. 6.

Description of embodiments

[0008]

In cases where multilayer nonwoven fabrics are manufactured by superimposing a plurality of nonwoven fabrics on top of each other and bonding the nonwoven fabrics to form one whole by hot embossing, as disclosed in Patent Documents 1 and 2, it is difficult to reduce the basis weight of each of the layers forming the multilayer structure and in features difficult to reduce the surface density of the hydrophobic layer. Thus, the multilayer nonwoven fabric generally has a high basis weight and high rigidity, which can lead to a decrease in wearing comfort in cases where the multilayer nonwoven fabric is used as a constituent member of an absorbent article. In addition, placing the hydrophobic layer at a location closest to the wearer's skin may result in poor absorption of body fluids such as sweat and urine.

[0009]

A known method of making multilayer nonwoven fabrics includes: sequentially lowering and laying fibers emerging from a plurality of forming heads spaced in the machine direction (MD), and bonding a stack of fibers by means of hot embossing at a location behind a forming head located further all along the machine direction. Multilayer nonwoven fabrics made by this method, which is called continuous spinning, have relatively low basis weight and low stiffness. Thus, even in cases where the hydrophobic layer of the nonwoven material is located at a location closest to the skin of the wearer released by the body, fluid can be absorbed from the periphery of the embossed portions in the hydrophobic layer. However, the constituent fibers of the hydrophilic layer adjacent to the hydrophobic layer have a high density at the periphery of these embossed portions. In addition, in such nonwoven fabrics, the thickness of the hydrophobic layer is relatively thin. Thus, fluid excreted by the body tends to accumulate at the periphery of the embossed portions, and this can lead to rewetting.

[0010]

The present invention relates to an absorbent article and absorbent sheet that are unlikely to induce rewet and that have very good ability to absorb body fluids such as sweat and urine.

[0011]

The present invention is described below with reference to the drawings in accordance with preferred embodiments. FIG. 1 schematically illustrates, along the thickness direction Z, a cross-section of a multilayer nonwoven fabric 10, which is an embodiment of a multilayer nonwoven fabric used in an absorbent article of the present invention. The multilayer nonwoven fabric 10 has a multilayer structure 13 in which a plurality of fibrous layers are superimposed on each other. Typically, each fibrous layer is a corresponding nonwoven forming layer, that is, a single layer nonwoven fabric (e.g. a spunbond nonwoven fabric) or a multilayer nonwoven fabric (e.g. an SMS nonwoven fabric (spunbond layer (S) - meltblown layer (M) - spunbond layer (S)) The multilayer structure 13 has a first surface 10a defining one surface of the multilayer nonwoven fabric 10 and a second surface 10b defining the other surface of the multilayer nonwoven fabric 10 and located on the side opposite to the first surface 10a.

[0012]

One of some key features of the multilayer nonwoven fabric 10 is that the multilayer structure 13 has a hydrophilicity gradient in the thickness Z direction. More specifically, in the multilayer structure 13, the first surface 10a is formed by a hydrophilic first layer 11 including hydrophilic fibers, and a hydrophobic second layer 12 including hydrophobic fibers is disposed on the side of the second surface 10b relative to the first layer 11; with this configuration, the multilayer structure 13 will be made with a gradient of the degree of hydrophilicity, with the side of the first surface 10a having a relatively higher degree of hydrophilicity than the side of the second surface 10b.

The fibers forming the first layer 11 are also referred to as the first fibers 14, and the fibers forming the second layer 12 are also referred to as the second fibers 15.

[0013]

In the multilayer nonwoven fabric 10 illustrated in FIG. 1, the multilayer structure 13 is a two-layer structure including a hydrophilic first layer 11 and a hydrophobic second layer 12, wherein the first surface 10a is formed by the first layer 11 and is hydrophilic, while the second surface 10b is formed by the second layer 12 and is hydrophobic. ... In this document, the expression “the number of layers in the multilayer structure 13 is two” refers to the total number of layers in two layers (first layer 11 and second layer 12) having different shapes or functions, and does not necessarily correspond to the number of fibrous layers (nonwovens) in a strict sense. More specifically, as further described below, each of the first layer 11 and the second layer 12 is not limited only to a nonwoven having a single layer structure, but may also be a nonwoven fabric with a multilayer structure (for example, an SMS nonwoven fabric) having two or more layers. For example, in cases in which the first layer 11 is a nonwoven fabric having a single layer structure and the second layer 12 is a nonwoven fabric with an SMS structure, the multilayer structure 13 is a two layer structure including the first layer 11 and the second layer. 12, but the actual number of layers of nonwoven fabrics is four in total, including one layer in the first layer 11 and three layers in the second layer 12. The point is that each of the first layer 11 and the second layer 12 may include two or more layers.

[0014]

In the present invention, the degree of hydrophilicity of the fibrous layer (nonwoven fabric), which is an accumulation of fibers, is determined based on the angle of contact with water measured according to the method described below. If the contact angle is less than 90 degrees, the fibrous layer is hydrophilic; if the contact angle is 90 degrees or more, the fibrous layer is hydrophobic. The smaller the angle of contact with water, determined in accordance with the method below, the higher the degree of hydrophilicity (or the lower the degree of hydrophobicity); the larger the contact angle, the lower the degree of hydrophilicity (or the higher the degree of hydrophobicity). In the multilayer structure 13 of the multilayer nonwoven fabric 10, the contact angle of the hydrophilic first layer 11, determined according to the method below, is less than 90 degrees, and the contact angle of the hydrophobic second layer 12, determined according to the following method, is 90 degrees or more.

[0015]

{Method for determining the angle of contact of the fibrous layer}

From the fibrous layer to be measured, a measurement sample is cut, having a rectangular shape in plan view, a length of 150 mm in the machine direction and a width of 70 mm in the transverse direction. A drop of ion-exchange water is dropped on the surface of the sample for measurement, on which the contact angle is to be measured, and the water drop is recorded to measure the contact angle based on the recorded image. More specifically, the measuring device used is a microscope (VHX-1000 from Keyence Corporation), which has a variable focal length medium magnification lens attached in a state in which it is tilted at a 90 ° angle. The sample for measurement is placed on the measuring stage of the measuring device so that the measurement surface is facing upwards and so that the sample for measurement can be viewed in the transverse direction. Thereafter, a drop of ion-exchange water with a volume of 3 μL is dropped onto the surface of the measurement sample, which has been placed on the measuring stage, to be measured, and images of the water drop are recorded and captured by the measuring device. Ten images are selected from the recorded images, in which one or both edges of the water drop in the transverse direction can be clearly seen, and the contact angle with the water drop is measured in each of the ten images. The average value of the measured contact angles is considered as the contact angle of the fibrous layer as a measurement object. The measuring medium has a temperature of 20 ° C and a relative humidity of 50%.

[0016]

The first layer 11 is formed mainly by hydrophilic fibers and is therefore a hydrophilic layer. The second layer 12 is preferably composed of substantially hydrophobic fibers and is therefore a hydrophobic layer. The first layer 11 includes at least 50% of the mass. hydrophilic fibers, and the content of hydrophilic fibers can be 100% of the mass. from the total mass of the first layer 11. The second layer 12 is formed mainly by hydrophobic fibers and includes at least 90% of the mass. hydrophobic fibers; the content of hydrophobic fibers can be 100% of the mass. from the total mass of the second layer 12.

[0017]

In the present invention, the contact angle of the hydrophilic fiber determined according to the following method is less than 90 degrees, and the contact angle of the hydrophobic fiber is 90 degrees or more. The degree of hydrophilicity of the fiber is determined based on the angle of contact with water, determined according to the method below; the fiber is hydrophilic when the contact angle is less than 90 degrees, and the fiber is hydrophobic when the contact angle is 90 degrees or more. The smaller the contact angle determined in accordance with the method below, the higher the degree of hydrophilicity (or the lower the degree of hydrophobicity); the larger the contact angle, the lower the degree of hydrophilicity (or the higher the degree of hydrophobicity).

[0018]

{Method for determining the angle of contact between fibers}

Fibers extracted from each of the first layer and the second layer of the multilayer nonwoven fabric by using scissors and tweezers are the subject of measurement. Five pieces of fiber were taken from each of the first layer and the second layer, and the contact angle of each piece of fiber was measured.

MCA-J Automatic Contact Angle Measuring Instrument from Kyowa Interface Science Co., Ltd. used as a measuring device. Deionized water is used to measure the contact angle. The amount of liquid discharged from the jet type ejector for ejecting water droplets (Pulse Injector CTC-25 from Cluster Technology Co., Ltd. with an outlet diameter of 25 μm) was set to 15 picoliters, and a drop of water was dropped exactly on fiber. The manner in which the droplet descends is recorded by means of a high-speed recording device connected to a horizontally mounted camera. For reasons related to the subsequent analysis of the captured images, the recording device is preferably a personal computer in which a high-speed image capture device is built in. In this measurement, images are recorded every 17 ms. The first recorded video that shows a drop of water falling on the fiber is analyzed using the accompanying FAMAS software (software version: 2.6.2; analysis method: resting drop method; analysis method: θ / 2 method; image processing algorithm : non-reflective; image type in image processing: frame; threshold level: 200; curvature correction: none) for calculating the angle formed between the fiber and the water drop-air interface, which is considered as the contact angle. Fibers extracted from each measuring object are cut to a fiber length of 1 mm and the fiber is placed on a sample support in the contact angle tester and held horizontally thereon. For one piece of fiber, the contact angle is measured at two different locations. In accordance with this method, the contact angle is measured for each of the five recovered pieces of fiber to the first decimal place, and the average (rounded to the first decimal place) of the measured values obtained in a total of ten locations is determined as the contact angle of the fibers with water. The measuring medium has a temperature of 22 ± 2 ° C and a relative humidity of 65 ± 2%. The smaller the contact angle, the higher the degree of hydrophilicity.

[0019]

In the case where a sample for measurement (for example, a fiber) is included in a constituent element (for example, a topsheet or absorbent sheet) of an absorbent article, the sample for measurement can be removed according to the following methods. In cases in which a constituent element including a measurement sample is attached to another constituent element by adhesive, fusion bonding, etc., it may be necessary to remove the bonding to remove the constituent element including the measurement sample from absorbent product. In cases in which a constituent member including a measurement sample is not attached to another constituent element, the measurement sample can be removed directly from the absorbent article. As for the method for removing the attachment of the constituent member, it is preferable to first reduce the strength of the adhesive, etc., used in the absorbent article to bond the constituent member to be measured and the other constituent member by using a coolant such as cold spray, and then gently separate and extract the constituent element to be measured. This extraction method can be applied to various measurements used for measurement objects in the present invention, for example, in interfiber distance measurement and fineness measurement, described further below. It should be noted that for reasons of minimizing the effect on the hydrophilic agents applied to the constituent elements, it is preferable not to use methods that can cause the destruction or elimination of oily agents, such as applying a solvent or blowing hot air with a dryer, to eliminate bonded parts.

[0020]

The first layer 11 includes fibers that do not lend themselves to fusion bonding. It is preferable that the first layer 11 is formed mainly of fibers that are not amenable to fusion bonding. In addition, as described above, the first layer 11 is a hydrophilic layer, so it is preferable that the first layer 11 is formed by mainly hydrophilic fibers that cannot be fused together. The expression "composed mainly of hydrophilic fibers that cannot be fused together" means that the content of hydrophilic fibers that cannot be fused together is higher than that of other fibers. For example, it is preferable that in the first layer 11 the content of hydrophilic fibers that cannot be bonded by fusion was 50 wt%. or more with respect to the total weight of the first layer 11. The content of hydrophilic fibers that cannot be bonded by fusion may be 100% of the mass. in relation to the total mass of the first layer 11.

Examples of non-fusion hydrophilic fibers that can be used include natural fibers, hydrated cellulose fibers, or semi-synthetic fibers. Examples of natural fibers include cotton fibers, silk, cellulose fibers, and lyocell fibers, which are purified cellulose fibers. Examples of cellulose hydrate fibers include regenerated fibers such as rayon fibers and copper-ammonia fibers. Examples of semi-synthetic fibers include acetates.

Hydrophilic fibers of the same type, not amenable to bonding by the method of fusion, can be used separately, or two or more types can be used in combination.

[0021]

In addition to the aforementioned hydrophilic fusion-bonding fibers, the first layer 11 may include fusion-bonding hydrophilic fibers. Fusion-bonding hydrophilic fibers may include fibers that have been hydrophilic treated so that the contact angle is less than 90 degrees. Examples of such fibers include fibers including a hydrophilizing agent mixed therein, fibers having a hydrophilizing agent adhered to their surface, or plasma-treated fibers. There is no particular limitation on the hydrophilizing agent as long as it is a hydrophilizing agent commonly used for hygiene products.

Hydrophobic fibers can include fibers that have been treated to render them hydrophobic such that the contact angle is 90 degrees or greater. Examples of such fibers include fibers such as long fibers including a hydrophobic agent mixed therein, fibers having a hydrophobic agent adhered to their surface, or plasma-treated fibers. There is no particular limitation on the hydrophobic agent as long as it is a hydrophobic agent commonly used for hygiene products.

[0022]

The first layer 11 is preferably a nonwoven fabric formed by the aforementioned fibers included in the first layer 11, and more preferably a nonwoven fabric formed mainly by the aforementioned fusion-resistant fibers. Fibers not amenable to fusion bonding are preferably short fibers. More specifically, the first layer 11 is preferably a non-woven fabric made up mainly of non-fusion-bonding short fibers — that is, a non-woven fabric of non-fusion-bonding short fibers. Examples of such nonwovens include hydroentangled nonwovens, needle punched nonwovens, and chemically bonded nonwovens.

In the present invention, “short fibers” refers to fibers having a fiber length of 70 mm or less, preferably 64 mm or less.

In the present invention, "fiber length" refers to the average fiber length, which is determined according to the method below.

[0023]

{Determination of average fiber length}

The length of the fibers, which are the fibers forming the first layer or the second layer of the multilayer nonwoven fabric, are determined according to the method for determining the average fiber length (Method C) from JIS L1015 (JIS - Japanese Industrial Standard). In cases where the short fibers are composed of cellulose, the average fiber length is determined by measurement in accordance with JIS P8226: 2006 (Cellulosic materials: Determination of fiber length by automated optical analysis).

[0024]

The second layer 12 is formed mainly by long fibers. Long fibers will be further defined below.

The second layer 12 is formed primarily by fusion-bonding fibers. In this document, the expression "composed primarily of fusion-bonding fibers" means that the content of the fusion-bonding fibers is greater than the content of the non-fusion-bonding fibers. The aforementioned hydrophobic fibers are fusion-bonding fibers.

Examples of fusion bonding materials for long fibers include: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; and fiber resins such as polyacrylates, polyalkyl methacrylates, polyvinyl chloride, and polyvinylidene chloride. The aforementioned fiber of the same type can be used separately, or two or more types can be used in combination.

[0025]

The fibers used as constituent fibers of the second layer 12 can be monocomponent fibers formed from one type of synthetic resin, or from a mixed polymer formed by mixing two or more types of synthetic resins, or bicomponent fibers. In this document, bicomponent fibers refer to combined fibers that are obtained by combining synthetic resins of two or more types having different components by means of a spinneret and simultaneously forming fibers from the resins, and in which the components are bonded together in a single fiber in accordance with a continuous structure in the length direction fibers. Examples of types of bicomponent fibers include core and sheath fibers and side-by-side fibers, but are not particularly limited to these types.

[0026]

In the present invention, "long fibers" refers to fibers having a fiber length of 75 mm or more, preferably 100 mm or more. It is more preferable if the fibers are continuous long fibers having a fiber length of 150 mm or more, since a long fiber nonwoven fabric having a high tensile strength can be obtained. The upper limit of the fiber length for the aforementioned "long fibers" is not particularly limited. "Long fiber nonwoven fabric" generally refers to a nonwoven fabric including an agglomeration of fibers in which long fibers are interconnected by means of fusion bonded portions. Examples of such long fibrous nonwovens include: single layer nonwovens such as spunbond nonwovens and meltblown nonwovens; multilayer nonwoven fabrics formed by overlapping spunbond and / or meltblown layers formed mainly of long fibers, and nonwoven fabrics bonded by means of heated rolls and formed by carding. Examples of multilayer nonwovens include SS multilayer nonwovens (spunbond (S) - spunbed (S)), SSS multilayer nonwovens (spun (S) - spun (S) - spun (S)) , multilayer SMS nonwovens (spunbond layer (S) - meltblown layer (M) - spunbond layer (S)) and SMMS nonwovens (spunbond layer (S) - layer (M), melt-blown layer (M) melt-blown layer (S)). In general, long fiber nonwovens have higher strength than short fiber nonwovens.

[0027]

As illustrated in FIG. 1, the multilayer nonwoven fabric 10 includes in some portions in a plan view of the multilayer nonwoven fabric 10 interlayer bonded portions 16 in which the layers forming the multilayer structure 13 are bonded together, each of the interlayer bonded portions being thinner than the peripheral parts. In each interlayer bonded portion 16, a portion of the constituent fibers (second fibers 15) of the second layer 12 forming the multilayer structure 13 is melted and fusion bonded to the first layer 11, and thereby the first layer 11 and the second layer 12 are bonded together.

[0028]

In the multilayer nonwoven fabric 10, the interlayer bonded portions 16 are formed by squeezing the precursor material of the multilayer structure 13 (i.e., the laminate formed from the first layer 11 as a base layer and a stack of second fibers 15) from the side of the second surface 10b towards the side of the first surface 10a ... Due to this formation method, as illustrated in FIG. 1 and 2, a portion including each interlayer bonded portion 16 is recessed from the second surface 10b side towards the first surface 10a side. In other words, the interlayer bonded portion 16 is formed at the bottom of the depression 17 formed by pressing, such as embossing, as described below, and joins the first layer 11 and the second layer 12 together. In each compression recess 17, the constituent fibers of the first layer 11 and the second layer 12 are strongly compacted as compared to the portions peripheral to the recesses 17. In the multilayer nonwoven fabric 10, a plurality of interlayer bonded portions 16 are dispersed on each of the first surface 10a and the second surface 10b. In the embodiment illustrated in FIG. 1, the first surface 10a of the multilayer nonwoven fabric 10 is a flat surface having essentially no projections or depressions, while the second surface 10b is a projection-and-depressions surface having projections and depressions. In a plan view of each of the first surface 10a and the second surface 10b, the interlayer bonded portions 16 are formed according to the same configuration.

[0029]

The recess 17 — that is, the portion including the interlayer bonded portion 16 — is the portion in which the constituent fibers are compacted in the thickness direction. This consolidation is typically accomplished by embossing using a melt-promoting agent such as heat or ultrasonic waves to melt the fusion-bonded fibers, and more particularly using, for example, heat sealing or ultrasonic welding. When considering the manufacturing method, the portion including the interlayer bonded portion 16 may also be referred to as an embossed portion or a compressed / compressed portion.

[0030]

As illustrated in FIG. 1, the first layer 11 forming the multilayer structure 13 in this embodiment includes only the interlayer bonded portions 16. The first layer 11 may also include, in addition to the interlayer bonded portions 16, sealed portions (not illustrated) that are thinner than the peripheral parts, and in which the constituent fibers of the first layer 11 are strongly compacted. Such sealed portions are formed in the first layer in a pattern different from that of the interlayer connected portions 16 and have a higher density than the portions peripheral thereto.

Such sealed portions can be formed by squeezing the precursor material (web, which is a stack of first fibers 14) of the first layer 11 from the side of the first surface 10a towards the side of the second surface 10b or from the side of the second surface 10b towards the side of the first surface 10a ... Due to this forming method, each sealed portion is shaped to be recessed from the side of the first surface 10a towards the side of the second surface 10b or from the side of the second surface 10b towards the side of the first surface 10a. In addition, a plurality of such sealed parts are dispersed on the first surface 10a. As described above, the multilayer nonwoven fabric 10 may include densified portions on the first surface 10a, and thereby, the first surface 10a may be a projection surface with projections and recesses.

[0031]

By providing projections and depressions on one or both of the first surface 10a and the second surface 10b of the multilayer nonwoven fabric 10, the multilayer nonwoven fabric 10 may be positioned such that the surface with the projections and depressions will contact the skin of the wearer in cases in which, for example, the multilayer the nonwoven fabric 10 is used as a constituent element (eg, a sweat-absorbent sheet) of an absorbent article that can contact the skin of a wearer. Thus, a space is created between the multilayer nonwoven fabric 10 and the skin of the wearer, which allows moisture generated by the released body fluid such as sweat or urine to be efficiently dispersed through the space. Thus, the surface of the nonwoven laminate 10 with an improved dry feeling can be provided, and the wearing comfort of the absorbent article can be improved.

[0032]

In the multilayer nonwoven fabric 10, the second layer 12 forming the second surface 10b includes hydrophobic fibers and is therefore hydrophobic, and thus substantially difficult to absorb body fluids (aqueous fluid) such as sweat or urine. However, the interlayer bonded portions 16 and portions peripheral to them on the second surface 10b include not only hydrophobic fibers, but also include hydrophilic fibers of the first layer 11 - which is adjacent to the second layer 12 and has a higher degree of hydrophilicity, whereby these hydrophilic fibers are relatively dense and therefore have a higher degree of hydrophilicity (or a lower contact angle determined in accordance with the above method) compared to other parts of the second surface 10b. Thus, on the second surface 10b, the fluid excreted by the body can preferentially adhere to the multi-layer connected portions 16 and the portions peripheral thereto. As described above, the multilayer structure 13 is made with a gradient of the degree of hydrophilicity in the Z-direction of the thickness, with "the side of the first surface 10a having a relatively higher degree of hydrophilicity than the side of the second surface 10b". Consequently, bodily secreted fluid adhering to the multilayer bonded portions 16 and the peripheral portions thereof on the second surface 10b is easily drawn into the multilayer nonwoven fabric 10 mainly through the peripheral edge of the interlayer bonded portions 16 and the area around it. The peripheral edge of each interlayer bonded portion 16 is the boundary between the portion in which the constituent fibers (second fibers 15) of the second layer 12 have been melted by compression, such as embossing, and the portion in which the fibers are not melted. The area in the vicinity of the interlayer bonded portion 16 / the vicinity of the interlayer bonded portion 16 is a different portion from the interlayer bonded portion 16 in the recess 17, and is a portion in the recess 17 in which the constituent fibers (second fibers 15) of the second layer 12 surrounding the interlayer bonded part 16, accumulated with a high density of arrangement, but still retain their fiber shape.

[0033]

For reasons related to a more reliable provision of the liquid absorption effect due to the gradient of the degree of hydrophilicity, it is preferable that, based on the fact that the contact angle of the constituent fibers (hydrophobic fibers) of the second layer 12 is greater than the contact angle of the constituent fibers (hydrophilic fibers) of the first layer 11, the angle the contact of the constituent fibers 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. In addition, based on the fact that the contact angle of the constituent fibers (hydrophilic fibers) of the first layer 11 is less than the contact angle of the constituent fibers (hydrophobic fibers) of the second layer 12, the contact angle of the constituent fibers of the first layer 11 is preferably 5 degrees or more, more preferably 10 degrees. or more, and preferably 88 degrees or less, more preferably 85 degrees or less. The degree of hydrophilicity of the constituent fibers can be controlled by adjusting, for example, the type and / or content of the hydrophilic agent as appropriate.

[0034]

For reasons of improving the liquid wicking effect by the gradient of the hydrophilicity, it is preferable that in the first layer 11, the hydrophilicity on the first surface 10a side is relatively low and the hydrophilicity on the second surface 10b side is relatively high. With this configuration, body fluid that has been drawn into the multilayer nonwoven fabric 10 can be absorbed and held by the hydrophilic first layer 11 from the inner thickness in the Z direction while diffusing it in the in-plane direction (i.e., the direction orthogonal to the thickness direction Z) of the multi-layer nonwoven fabric 10.

[0035]

Each of the interlayer bonded portions 16 is a bonded portion in which constituent fibers of the second layer 12 are melted and fused to the first layer 11. The constituent fibers of the first layer 11 in each interlayer bonded portion 16 still maintain their fiber shape, as illustrated in FIG. 1 and 2. On the other hand, the constituent fibers of the second layer 12 in each interlayer portion 16 are melted by heating, for example, by embossing, and therefore become constituent resin 15a in which the fiber shape has been lost. A portion of the molten resin constituent 15a passes between the constituent fibers of the first layer and solidifies, as illustrated in FIG. 2. In the portion overlapping each of the interlayer bonded portions 16 in the thickness direction Z, the first layer 11 of the multilayer nonwoven fabric 10 of this embodiment has a portion into which the molten resin constituent 15a of the second fibers 15 has entered and a portion into which the molten constituent resin did not enter. In the first layer 11 of the multilayer nonwoven fabric 10, the constituent resin 15a may be included in the portion overlapping each interlayer bonded portion 16 in the thickness direction Z along its entire length, but it is preferable that there are portions in which the constituent resin 15a formed by melting the second fibers 15 are not included as in this embodiment.

It should be noted that it is sufficient for a portion of the constituent fibers of the second layer 12 to be melted in each interlayer portion 16.

[0036]

As described above, since the resin fibers of the interlayer bonded portion 16 in each recess 17 are strongly compacted compared to the periphery of the recess 17, liquid such as sweat is likely to adhere thereto. On the other hand, at and in the vicinity of the peripheral edge of the interlayer bonded portions 16, the constituent fibers (second fibers 15) of the second layer tend to retain their fiber shape, unlike the interlayer bonded portions 16, and therefore liquid can easily pass between the second fibers 15 behind by adhering to the second fibers 15, which retain their fiber shape. In other words, the liquid that has entered each recess 17 can easily be drawn towards the side of the first surface 10a from the peripheral edge and from the vicinity of the interlayer bonded portion 16 in the recess 17. Thus, the peripheral edge and the vicinity of the interlayer bonded portion 16 in each the recess 17 serves as a liquid intake zone.

In addition, in each interlayer bonded portion 16, the constituent fibers of the first layer 11 retain their fiber shape, while the constituent resin 15a, which is the melted portion of the constituent fibers of the second layer, passes between the constituent fibers of the first layer 11. Thus, at the peripheral at the edge of the interlayer bonded portion 16, the first fibers 14 of the first layer pass between the second fibers 15 of the second layer, mixing with them, and therefore, liquid can be easily drawn from the side of the second surface 10b to the side of the first surface 10a.

In addition, the second layer is formed mainly by long fibers. Thus, the second fibers 15 are oriented in the in-plane direction of the nonwoven laminate, which reduces the thickness of the second layer. In addition, the thickness of the second layer is likely to be further reduced by the formation of interlayer bonded portions 16. Thus, liquid that has penetrated the peripheral edge and the vicinity of each interlayer bonded portion 16 can easily come into contact with the hydrophilic first fibers 14 of the first layer. 11, whereby it is possible to easily absorb liquid on the side of the second surface 10b.

Thus, the multilayer nonwoven fabric 10 has very good absorbency due to the aforementioned gradient of the degree of hydrophilicity, the configuration of the peripheral edge and the vicinity of each interlayer bonded portion 16, which serve as a liquid suction zone, the configuration of the portions in which the second fibers 15 are the hydrophobic constituents of the fibers of the second layer 12, and the first fibers 14, which are the hydrophilic constituents of the fibers 14 of the first layer 11, and the provision of thin portions in the second layer 12, in which the distance to the first layer 11 is small.

[0037]

In cases where the first layer 11 includes short fibers, the short fibers will be oriented not only in the direction in the plane of the multilayer nonwoven fabric, but also in the direction of the thickness, whereby an effect is obtained that the hydrophilic first fibers 14 will easily pass between the hydrophobic second fibers 15, oriented in the direction in the plane of the second layer 12.

[0038]

As described above, in the portion overlapping each of the interlayer bonded portions 16 in the thickness direction Z, the first layer 11 of the multilayer nonwoven fabric 10 of this embodiment has a portion into which the molten resin constituent 15a of the second fibers 15 is received and a portion into which the molten no resin constituent was included (see Figs. 1 and 2). With this configuration, in portions other than the interlayer bonded portions 16 in the in-plane direction of the multilayer nonwoven fabric, the fibers of the first layer 11 on the second surface 10b side are bonded together by the melted second fibers 15 and are therefore compacted more strongly than the fibers on the first surface side 10a. On the other hand, on the first surface 10a side of the first layer 11, the first fibers 14 are not bonded in the thickness direction, and therefore the inter-fiber distance is large. This creates a fiber density gradient between the side of the first surface 10a and the side of the second surface 10b also within the first layer 11, whereby the effect of retaining liquid within the multilayer nonwoven fabric 10 is achieved.

[0039]

The peripheral edge and the vicinity of the interlayer bonded portion 16 in each recess 17 are important portions serving as a liquid suction zone in cases where liquid is absorbed from the hydrophobic second surface 10b. On the other hand, since the hydrophobic second layer 12 and the hydrophilic first layer 11 are bonded together in each interlayer bonded portion 16, a portion of the constituent fibers of the second layer 12 in the interlayer bonded portion 16 lose their fiber form as fusion-bonded fibers and become a molten constituent resin 15a; thus, in cases where the multilayer nonwoven fabric 10 is compressed in the thickness direction after absorbing the liquid (for example, when pressure from the wearer's body is applied to the multilayer nonwoven fabric 10 in cases where the multilayer nonwoven fabric 10 is used as a constituent member of an absorbent article with the second surface 10b facing the skin side of the wearer), by the resin constituent 15a, that is, the interlayer bonded portions 16, rewetting of the second surface 10b side is effectively suppressed. Thus, in cases where the multilayer nonwoven fabric 10 is used as a member of an absorbent article that contacts the skin of the wearer, a very good texture to the touch can be obtained, for example, no stickiness, even after absorption of a body fluid such as sweat. , multi-layer nonwoven fabric 10.

The shape of the fibers constituting the fiber in the interlayer bonded portions 16 is mainly influenced by the embossing conditions during the formation of the interlayer bonded portions 16; with relative softening of the heating / squeezing conditions during embossing, it is possible for the fibers constituting the fibers to retain their shape.

[0040]

The second layer 12 of this embodiment includes, in some portions in a plan view of the multilayer nonwoven fabric, fused bonded portions in which fusion-bonded fibers are bonded together. Fused bonded portions are portions in which the constituent fibers of the second layer 12 are melted and solidified. For reasons of improving the liquid-draw ability, it is preferable that the fused bonded portions form part of the second layer in the corresponding interlayer bonded portion 16. In other words, it is preferable that the fused bonded portions form part of the second layer 12 in each interlayer bonded portion 16 in the direction the thickness of the multilayer nonwoven fabric, that is, the portion in each interlayer bonded portion 16 in which the constituent fibers of the second layer have been melted. In this case, the constituent fibers (second fibers) melted in the fused bonded portions pass between the constituent fibers of the first layer 11, retaining their fiber shape, and solidify. It is preferred that at least half of the fused bonded portions form part of the second layer in each interlayer bonded portion 16, and more preferably, all fused bonded portions form part of the second layer in each interlayer bonded portion 16.

[0041]

The interlayer bonded portions 16 are formed in some portions in a plan view of the multilayer nonwoven fabric 10, but there are no particular restrictions on the configuration of these portions when they are formed. FIG. 3 illustrates examples of configurations (plan view shapes and layouts) of the interlayer bonded portions 16. It should be noted that the configuration of the interlayer bonded portions 16 when formed on the first surface 10a or the second surface 10b is not limited to those illustrated in FIG. 3, and any given configuration can be used within a scope that does not deviate from the spirit of the present invention.

FIG. 3 (a) -3 (c) illustrate configurations in which a plurality of interlayer bonded portions 16, each having a predetermined shape in a plan view, are provided dispersed in a plane direction (i.e., a direction orthogonal to the thickness direction of the multilayer nonwoven fabric 10 ). The shape of each interlayer connected portion 16 in plan view is elliptical (oval) in FIG. 3 (a), circular in FIG. 3 (b) and square / rhombic in FIG. 3 (c). FIG. 3 (d) illustrates a configuration in which interlayer bonded portions 16 having a linear shape in a plan view are arranged to extend in predetermined directions. More specifically, a plurality of continuous lines formed by the interlayer connected portions 16 are arranged to intersect with each other, and the interlayer connected portions 16 form a generally lattice configuration.

[0042]

As described above, the peripheral edge and the vicinity of each interlayer bonded portion 16 are portions serving as a liquid suction zone in cases where liquid is absorbed from the second surface 10b side. Thus, for reasons of enhancing the liquid-wicking capacity of the multilayer nonwoven fabric 10, it is preferred that the second surface 10b has a dispersed, interlayer bonded portion area in which a plurality of interlayer bonded portions 16 are dispersed in a plane direction. The provision of the second surface 10b with the aforementioned area of dispersed interlayer bonded portions is particularly advantageous in cases where the multilayer nonwoven fabric 10 is to be used as a sweat absorbent sheet, since the sweat absorption capacity can be further enhanced. The entire area of the second surface 10b may form an area of dispersed, interlayer connected portions, or only a portion of the second surface 10b may form an area of dispersed, interlayer connected portions. The area fraction of the area of the dispersed, interlayer connected portions of the total area of the second surface 10b is preferably 70% or more, more preferably 80% or more.

[0043]

эффективность обеспечивается, если межслойные соединенные части 16 удовлетворяют вышеописанному условию в случаях, когда вышеупомянутый воображаемый круг имеет радиус 1,5 мм.With regard to the arrangement of the interlayer connected parts 16 in the area of the dispersed interlayer connected parts, it is preferable that a part of at least one interlayer connected part 16 or all of at least one interlayer connected part 16 is enclosed within an imaginary circle having a radius of 2 mm and made virtually in an arbitrary place within the zone of dispersed, interlayer connected parts, which is the zone of the second surface 10b. In this document, the expression "part of at least one interlayer connected part 16 or all of at least one interlayer connected part 16 is enclosed within an imaginary circle having a radius of 2 mm and made virtually in an arbitrary place" means that if ten such imaginary circles are provided in the area of dispersed, interlayer connected parts, representing the area of the second surface 10b, one or two of these ten imaginary circles should not / should not necessarily include the interlayer connected part 16, and it will be sufficient that each of the remaining eight imaginary circles included a portion of at least one interlayer bonded portion 16 or all of at least one interlayer bonded portion 16. The aforementioned imaginary circles are assumed to represent sweat-secreting portions (sweat glands) dispersed over the skin surface of the human body ... Making the multilayer nonwoven fabric 10 with the above-mentioned configuration makes it possible to absorb perspiration more efficiently. More

efficiency is obtained if the interlayer connected portions 16 satisfy the above condition in cases where the above imaginary circle has a radius of 1.5 mm.

[0044]

The portions including the interlayer bonded portions 16 serve as liquid suction zones on the second surface 10b, and therefore, for reasons of providing sufficient liquid wicking capacity for practical use, a certain number of interlayer bonded portions 16 must be provided. In other words, the length of the periphery of each interlayer bonded portion 16 must be at least a certain amount. On the other hand, it is not preferable that the area of the interlayer bonded portions 16 is too large; in addition, if there are too many interlayer bonded portions 16 on the second surface 10b, the amount of liquid that can be absorbed by the first layer 11 and can be retained therein may decrease, since in the interlayer bonded portions 16 not only the hydrophobic second layer 12, but also also the hydrophilic first layer 11 is fusion bonded. For these reasons, it is preferable that the percentage of the total area of the interlayer connected portions 16 (i.e., the total area of the interlayer connected portions 16 in cases where a plurality of interlayer connected portions 16 are formed on the second surface 10b) of the area of the second surface 10b, i.e. as a percentage, the area ratio of the interlayer connected portions 16 is preferably 15% or less, more preferably 12% or less. The lower limit of the aforementioned percentage is preferably 5% or more, more preferably 6% or more.

[0045]

Each interlayer bonded portion 16 is continuous throughout the multilayer structure 13 (multilayer nonwoven fabric 10) in the thickness direction Z, and thus the configuration (plan view shape and layout) of the interlayer bonded portions 16 is substantially the same in the first surfaces 10a and second surface 10b in plan view. Therefore, the explanation in this Description regarding the configuration of the interlayer bonded portions 16 on the second surface 10b (e.g., the area of the dispersed, the interlayer bonded portions, expressed as a percentage of the area fraction of the interlayer bonded portions 16, etc.) is also applicable to the first surface 10a. unless specifically stated otherwise.

[0046]

Likewise, for reasons of both liquid absorption and rewet prevention, it is preferable that the area of one interlayer bonded portion 16 on the second surface 10b is preferably 1 mm ² or less, more preferably 0.8 mm ² or less, and its lower limit is preferably 0.1 mm ² or more, more preferably 0.15 mm ² or more.

[0047]

The basis weight of the first layer 11 and the second layer 12 is not limited to a particular value and can be appropriately adjusted depending on, for example, the use of the multilayer nonwoven fabric 10. For example, in cases where the multilayer nonwoven fabric 10 is used as a constituent element (top sheet, absorbent sheet, etc.) of an absorbent article, such as a disposable diaper or sanitary napkin, for reasons of strength sufficient for practical use while suppressing bulk, it is preferred that the combined basis weight of the first layer 11 and the second layer 12 is preferably 11 g / m ² or more, more preferably 14 g / m ² or more, and preferably 55 g / m ² or less, more preferably 50 g / m ² or less.

[0048]

In particular, in cases where the first layer 11 diffuses and retains the liquid absorbed through the hydrophobic second layer 12 (second surface 10b), the basis weight of the first layer 11 will be related to the ability to absorb liquid; in general, the higher the basis weight of the first layer 11, the higher the absorbency and the higher the strength. On the other hand, if the basis weight of the first layer 11 is too high, the multilayer nonwoven fabric may become bulky or stiff; this can lead to a decrease in the wearing comfort in cases where a multilayer nonwoven fabric is used as a constituent member of an absorbent article. In view of the above factors, the basis weight of the first layer 11 is preferably 8 g / m ² or more, more preferably 11 g / m ² or more, and preferably 40 g / m ² or less, more preferably 35 g / m ² or less.

[0049]

In cases where the multilayer nonwoven fabric 10 is used to absorb liquid, the hydrophobic second layer 12 is usually the side that first contacts the liquid. In this type of use, liquid can easily be absorbed through the peripheral edge and the vicinity of the interlayer bonded portions 16 on the second surface 10b if the second layer 12 has a relatively low basis weight and low thickness. On the other hand, for reasons of rewet and strength reduction, the second layer 12 must have at least a certain level of basis weight. In view of the above factors, the surface density of the second layer 12 is preferably 3 g / m ² or more, more preferably 5 g / m ² or more and preferably 25 g / m ² or less, more preferably 15 g / m ² or less, still more preferably 13 g / m ² or less. It should be noted that in the manufacture of multilayer nonwoven fabric 10 at least a certain level of basis weight is usually required for reasons related to the strength of the second layer 12; however, in the production of the multilayer nonwoven fabric according to the method further described below, the second layer 12 is produced by the so-called continuous-blow molding method, in which case production can be carried out without any problems even when the basis weight is only 3 g / m ² .

[0050]

As described above, different types of nonwoven fabrics can be used for the first layer 11 and the second layer 12. However, for reasons related to more reliably providing the above effects in cases where the multilayer nonwoven fabric 10 is used to absorb liquid, for example, in cases where when a multilayer nonwoven material is used as a constituent element of an absorbent article, it is particularly preferred that the hydrophilic first layer 11 is an air-bonded nonwoven fabric, a heated roll bonded nonwoven fabric, or a hydroentangled nonwoven fabric made by mixing or overlapping fusion-bonding fibers made from resin that is coated or mixed with a hydrophilizing agent and hydrophilic fusion-bonding fibers.

[0051]

Other preferable examples of the hydrophilic first layer 11 include air-bonded, nonwoven, or heated roll bonded nonwoven including 70 wt% hydrophilic fibers. or more, more preferably 75% of the mass. or more, and more preferably include an air-through nonwoven fabric or a hydroentangled nonwoven fabric in which the aforementioned densified portions are formed along their entire length. In a nonwoven fabric bonded by passing air through or a nonwoven fabric bonded by heated rollers, the area of one compacted portion is preferably 0.1 mm ² or more, more preferably 0.15 mm ² or more, and preferably 1 mm ² or less, more preferably 0.8 mm ² or less. In addition, on one surface of the air-bonded nonwoven fabric or the heated roller bonded nonwoven fabric, the number of densified parts per unit area, which is a square with a side length of 10 mm, is preferably four or more, more preferably six. or more, and preferably 30 or less, more preferably 28 or less.

[0052]

As the hydrophobic second layer 12, it is preferable to use a spunbond nonwoven, a meltblown nonwoven, or a multilayer nonwoven of these materials (for example, an SMS nonwoven), since the thickness is relatively thin, allowing for relatively easy absorption. liquids.

[0053]

The hydrophilic fibers included in the first layer 11 can be obtained by subjecting the fibers to a hydrophilic treatment. In other words, the first layer 11 may include an accumulation of fibers (eg, fusion-bonding fibers) that have been treated to render them hydrophilic. For the treatment to render hydrophilic, for example, coating the fibers or fiber aggregate with a hydrophilizing agent, mixing the hydrophilizing agent into the fibers, or using a plasma treatment, but generally a hydrophilizing agent is used.

[0054]

An example of the first layer 11 is a configuration in which the side of the second surface 10b is coated with a hydrophilizing agent (i.e., the hydrophilizing agent adheres to the surface of the constituent fibers from the side of the second surface 10b). The side of the first layer 11 on the side of the second surface 10b is the side opposite to the first surface 10a and is the surface that comes into contact with the layer adjacent to the first layer 11 - that is, with a surface having a lower degree of hydrophilicity than the first layer 11 (i.e., hydrophobic second layer 12 in the embodiment illustrated in FIG. 1). In the first layer 11 having the above configuration, there is more hydrophilizing agent on the side of the second surface 10b, which adheres to the surface of constituent fibers, such as fibers that cannot be fusion bonded, than on the side of the first surface 10a. Thus, the first layer 11 has a gradient of the degree of hydrophilicity in which the side of the first surface 10a has a relatively lower degree of hydrophilicity and the side of the second surface 10b has a relatively higher degree of hydrophilicity. In cases where the side of the first layer 11 on the side of the second surface 10b has a higher degree of hydrophilicity than the side on the side of the first surface 10a, as described above, a gradient of the degree of hydrophilicity is formed in the multilayer structure 13 in which the degree of hydrophilicity increases stepwise (i.e., the angle the contact determined in accordance with the above method decreases in steps) from the hydrophobic second layer 12 (second surface 10b), which first comes into contact with the liquid to be absorbed, towards that side of the multilayer structure 13 which is inner in the direction Z of the thickness ... Therefore, a further increase in liquid absorption capacity can be expected.

[0055]

The method for applying the hydrophilizing agent is not limited to a particular method, and any known method for applying a coating solution including the hydrophilizing agent can be used as the case may be. Examples of suitable coating methods include engraved cylinder coating, contact coating, flexographic coating, spray coating, reverse roller coating and die coating, and among the above methods, engraving coating is particularly preferred. cylinder, flexographic coating, spray coating and die coating, which provide the ability to apply the coating in accordance with the specified pattern. Various types of surfactants used to render the constituents hydrophilic in absorbent articles such as disposable diapers can be used as a hydrophilizing agent without particular limitation.

[0056]

Another example of the first layer 11 is a configuration in which the hydrophilizing agent is applied to the constituent fibers (first fibers 14) in the spinning step or in the drawing step during the manufacture of the constituent fibers. In this case, each fiber is subjected to a hydrophilicity treatment, and therefore the hydrophilicity of the resulting nonwoven fabric is uniform and stable.

Alternatively, it is also possible to produce a first layer 11 having different degrees of hydrophilicity on the side of the first surface 10a and on the side of the second surface 10b, by stacking a plurality of webs formed from fibers having different degrees of hydrophilicity and subjecting the webs to hot air treatment on the stage of making the canvases in which the card is used. In this case, by using fibers having a higher degree of hydrophilicity for the first layer 11 on the side of the second surface 10b, it is possible to obtain a nonwoven fabric having a gradient in the degree of hydrophilicity, in which the side of the first surface 10a has a relatively lower degree of hydrophilicity and the side of the second surface 10b has a relatively higher degree of hydrophilicity. As described above, in cases where the first layer 11 on the side of the second surface 10b has a higher degree of hydrophilicity than on the side of the first surface 10a, a gradient of the degree of hydrophilicity is formed in the multilayer structure 13 in which the degree of hydrophilicity increases stepwise (i.e., the contact angle, determined in accordance with the above method, decreases in steps) from the hydrophobic second layer 12 (second surface 10b), which first comes into contact with the liquid to be absorbed, towards that side of the multilayer structure 13 which is inner in the thickness direction Z. Therefore, a further increase in liquid absorption capacity can be expected.

[0057]

In addition, during the creation of the nonwoven fabric for the first layer 11 by overlapping multiple webs formed from fibers having different degrees of hydrophilicity, as described above, an additional increase in liquid absorption can be expected when the fibers that are not fusion bonded are mixed. , such as cellulosic, cotton or hydrated cellulosic, from the side of the second surface 10b.

In this case, a description is given of a method for creating the first layer 11 by means of an air through-bonding method in which a nonwoven fabric is created by passing hot air through webs, but various other known methods of forming nonwoven fabrics such as using heated rollers, hydroentangling or needling may be used as a method for converting canvases to nonwoven fabric.

[0058]

The liquid wicking capacity of the multilayer nonwoven fabric 10 is influenced not only by the aforementioned gradient of the degree of hydrophilicity in the thickness direction, but also to a large extent by the thickness of the hydrophobic second layer 12. In the hydrophobic fibrous layer, a small interfiber spacing and a large thickness are factors that increase water resistance. Thus, in cases where the hydrophobic second layer 12 (second surface 10b) serves as the layer that first comes into contact with the liquid to be absorbed (i.e., the liquid-sucking layer), it is preferable that the thickness of the second layer 12 is small and the density of the fibers was low (that is, the interfiber spacing was large) to increase the liquid-wicking capacity of the nonwoven laminate 10. On the other hand, high capillary forces allow the hydrophilic layer (first layer 11 in the illustrated embodiment), which is adjacent to the second layer, to absorb liquid passing through the hydrophobic layer; thus, it is preferable that the fiber density of the hydrophilic layer is high (that is, the interfiber spacing is short). In the interlayer bonded portions 16 and the portions peripheral to them, the first fibers 14 of the first layer 11, which have a higher fiber density (i.e., a short interfiber spacing), are likely to be exposed to the action of the second surface 10b between the fibers of the second layers 12 (second surface 10b), which have a relatively low fiber density (i.e. long interfiber spacing). This allows liquid to be quickly drawn inwardly from the peripheral edge and from the vicinity of the interlayer bonded portions 16 on the second surface 10b, and allows for more stable absorption and retention of the drawn in liquid by the hydrophilic first layer 11. For these reasons, it is preferable that the first layer 11 has a higher density fibers than the second layer 12 - that is, the constituent fibers of the first layer have a shorter interfiber spacing than the second layer. It is also preferable that the constituent fibers of the first layer 11 on the side of the second surface 10b have a shorter interfiber distance than the constituent fibers on the side of the first surface 10a of the first layer 11. The interfiber spacing is determined according to the following method.

[0059]

{Method for determining interfiber distance}

The interfiber spacing for an accumulation of fibers, such as nonwoven fabric or paper, can be determined by means of formula (2), described later and based on the assumption of Wrotnowski. Formula (2) is generally used to determine the distance between fibers from a cluster of fibers. According to Wrotnowski's hypothesis, the fibers are circular-cylindrical and the fibers are aligned regularly without crossing each other.

In cases where the sheet to be measured (the first layer 11, the second layer 12) has a single layer structure, the interfiber spacing for the single layer structure sheet can be obtained by the formula (2).

In cases where the sheet to be measured (first layer 11, second layer 12) has a multilayer structure similar to an SMS nonwoven fabric, the interfiber spacing in the multilayer fibrous layer can be determined according to the following procedure.

First, the interfiber spacing in each fibrous layer forming the multilayer structure is calculated in accordance with formula (2). The thickness t, areal density W, resin density ρ of the fibers and the diameter D of the fibers used in formula (2) are values corresponding to the layer to be measured. Each parameter of thickness t, areal density W, and fiber diameter D is an average of the values measured at multiple measurement locations.

The thickness t (mm) is measured according to the method below. First, a piece with a length of 50 mm in the longitudinal direction and a width of 50 mm in the width direction is cut from the sheet to be measured to obtain a cut-out piece of sheet. However, if a cut piece of a given size cannot be obtained from a sheet to be measured, for example, in cases where the sheet is taken from a small size absorbent article, a cut piece is obtained that is as large as possible. Thereafter, the cut piece is placed on a flat plate and the flat glass plate is placed on it. The weight is evenly placed on the glass plate so that the load, including the weight of the glass plate, is 49 kPa, and the thickness of the cut piece is measured in this state. In the measurement environment, the temperature is 20 ± 2 ° C and the relative humidity is 65 ± 5%. A microscope (VHX-1000 from Keyence Corporation) was used as a measuring device. To measure the thickness of the cut-out piece, first, an enlarged image of the cut-out surface (section) is obtained. The enlarged image simultaneously captures a product with a known size. Further, the thickness of the cut piece — that is, the thickness of the sheet to be measured — is measured in accordance with a scale corresponding to an enlarged sectional view of the cut piece. The thickness in the area other than the interlayer bonded portions 16 is measured as the thickness of the sheet. The above process is performed three times, and the average of the three measurements is determined as the thickness t of the sheet to be measured. In cases where the sheet to be measured is a multi-layer product, the thickness is calculated by determining the boundary between the layers based on the diameter of the fibers.

The basis weight W (g / m ² ) is determined by cutting out the sheet to be measured with a predetermined size (e.g., 12 × 6 cm), measuring the mass of the cut piece, and dividing the measured weight value by the area calculated from the above specified size (Areal density W (g / m ²⁾ = Weight ÷ area, calculated from a predetermined size). The measurement is carried out four times and the average is determined as the basis weight.

The density ρ (g / cm ³ ) of the resin of the fibers is determined according to the method of measurement using a gradient tube for density determination described in JIS L1015 (Test Methods for Artificial Staple Fibers) by using a gradient tube for density determination (URL: http: / /kikakurui.com/l/L1015-2010-01.html; see also JIS Handbook Fibers (2000), Japanese Standards Association, pp. 764-765).

The fiber diameter D (μm) is an average value obtained by measuring the cross section of each of ten slices of cut fibers using an S-4000 field emission scanning electron microscope from Hitachi, Ltd. The method for measuring the fiber diameter D is the same as described hereinafter (Method for measuring fiber diameter).

Further, the interfiber spacing for the constituent fibers in a given multilayer sheet can be determined by first multiplying the interfiber spacing in each layer by a fraction of the thickness of the given layer in the entire thickness of the multilayer and then adding the values obtained for the respective layers. For example, for a nonwoven fabric with a three-layer SMS structure including two layers S and one layer M, the two layers S are considered together as one layer, and in cases where the total thickness t of the three-layer structure is 0.11 mm, the thickness t of the layer S is 0.1 mm, the interfiber distance LS for the S layer is 47.8 μm, the thickness t of the M layer is 0.01 mm, and the LS interfiber distance for the M layer is 3.2 μm, the distance between the fibers constituting the nonwoven fibers material with the SMS structure is 43.8 μm [= (47.9 × 0.1 + 3.2 × 0.01) / 0.11].

[0060]

[Math Expression 1]

(D: fiber diameter (μm); ρ: resin density of the fibers (g / cm ³ ); t: thickness (mm); W: surface density (g / m ² ))

[0061]

Based on the fact that the inter-fiber distance L2 between the constituent fibers (second fibers 15) of the second layer 12 is greater than the inter-fiber distance L1 between the constituent fibers (first fibers 14) of the first layer 11 (L1 <L2), as described above, it is preferable that the ratio (L2 / L1) the inter-fiber distance L2 between the constituent fibers (second fibers 15) of the second layer 12 to the inter-fiber distance L1 between the constituent fibers (first fibers 14) of the first layer 11 is preferably 1.1 or more, more preferably 10 or more, and preferably 70 or less more preferably 50 or less.

The inter-fiber distance L1 between the constituent fibers (first fibers 14) of 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 inter-fiber distance L1a between the constituent fibers (first fibers 14) on the first surface 10a side of the first layer 11 is preferably 10 µm or more, more preferably 15 µm or more, and preferably 100 µm or less, more preferably 80 µm or less. The fiber-to-fiber distance L1b between the constituent fibers (first fibers 14) of the first layer 11 on the side of the second surface 10b is preferably 5 μm or more, more preferably 7 μm or more, and preferably 80 μm or less, more preferably 70 μm or less. The interfiber distance L1a between the constituent fibers on the side of the first surface 10a of the first layer 11 is determined in the portion located at a distance in the thickness direction Z from the first surface 10a of the first layer 11, which is 50% of the thickness of the first layer 11. The interfiber distance L1b between the constituent fibers of the first layer 11 from the side of the second surface 10b is determined at a portion located at a distance in the thickness direction Z from the side of the first layer 11, which is 50% of the thickness of the first layer 11.

The inter-fiber distance L2 between the constituent fibers (second fibers 15) of the second layer 12 is preferably 7 µm or more, more preferably 10 µm or more, and preferably 200 µm or less, more preferably 150 µm or less.

[0062]

For reasons related to the production of a multilayer nonwoven fabric 10 with a density gradient such that the density of the fibers increases from the second layer 12 to the first layer 11 (that is, to that side of the multilayer structure 13, which is internal in the direction of thickness Z), and increasing the liquid wicking capacity thereby, as described above, it is preferable that the constituent fibers (first fibers 14) of the first layer 11 have a smaller fiber diameter than the constituent fibers (second fibers 15) of the second layer 12.

For the same reasons, it is preferable that the constituent fibers of the first layer 11 on the side of the second surface 10b have a smaller fiber diameter than the constituent fibers of the first layer 11 on the side of the first surface 10a.

The fiber diameter is measured according to the method below.

[0063]

{Method for measuring fiber diameter}

The object to be measured (fibrous layer or multilayer nonwoven fabric) is cut with a razor (for example, a single-blade razor from Feather Safety Razor Co., Ltd.) to obtain a measurement sample having a rectangular shape in plan view (8 x 4 mm). When cutting the object to be measured, be careful not to destroy the surface structure of the measuring specimen formed by cutting, by pressure, etc. during cutting. The preferred method for cutting the measuring object is to immerse the measuring object in liquid nitrogen and freeze the measuring object sufficiently before cutting, and then cutting the measuring object. Then, using double-sided paper tape (Nicetack NW-15 from Nichiban Co., Ltd.), the measurement sample was attached to the sample stage. The measurement sample is then plated with platinum. Coating was carried out using an E-1030 ion spraying device (product name) from Hitachi Naka Seiki, Ltd., with a spraying time of 30 seconds. The surface of the measurement sample obtained by cutting was examined at 1000x magnification with an S-4000 field emission scanning electron microscope from Hitachi, Ltd.

[0064]

It should be noted that, in the above fiber diameter measurement method, the measurement of the constituent fibers (first fibers 14) of the first layer 11 is performed by selecting fibers in an area other than the interlayer bonded portions 16, and where the fibers 14 of the first layer 11 are entangled with each other, in while the measurement of the constituent fibers (second fibers 15) of the second layer 12 is performed by selecting the constituent fibers (second fibers 15) that are in an area other than the interlayer bonded portions 16 and where the fibers of the second layer 12 are continuous between the interlayer bonded parts and are not fastened to each other. The length in the width direction with respect to the longitudinal direction of each fiber is measured for ten fiber pieces for each of the first fibers 14 and the second fibers 15, and the average is determined as the diameter of the fibers. The measurement of the constituent fibers on the side of the first surface 10a of the first layer 11 is performed by selecting fibers that are in a zone other than the interlayer bonded portions 16 and which are located on the surface on the side of the first surface 10a, and measurement of the constituent fibers on the first layer 11 from the side of the second the surfaces 10b are made by selecting fibers that are in an area other than the interlayer bonded portions 16 and that are located on the surface on the side of the second surface 10b.

In cases where the measurement object is a combined nonwoven material including a plurality of fibrous layers with different fiber diameters, such as an SMS nonwoven fabric or an SMMS nonwoven fabric, the liquid wicking capacity of the first layer 11 is significantly influenced by the layer obtained meltblown, in which the fibers are thin and the fiber density is high, and the liquid wicking capacity of the second surface 10b is significantly influenced by the meltblown layer in which the fibers of the second layer 12 are thin and the density fiber is high. In view of the foregoing, in cases in which the measurement item is a composite nonwoven fabric that is formed from a plurality of fibrous layers with different fiber diameters and which includes a meltblown layer, the measurement of the fiber diameter is performed by measuring the diameter of the fibers in the combined layer. meltblown nonwoven fabric.

[0065]

Assuming that the diameter D2 of the constituent fibers (second fibers 15) of the second layer 12 is greater than the diameter D1 of the constituent fibers (first fibers 14) of the first layer 11 (D1 <D2) as described above, preferably so that the ratio (D1 / D2) of the diameter D1 of the fibers constituting the constituent fibers (first fibers 14) of the first layer 11 to the diameter D2 of the fibers constituting the constituent fibers (second 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.

The diameter D1 of the fibers constituting the constituent fibers (first fibers 14) of the first layer 11 is preferably 0.5 µm or more, more preferably 1 µm or more, and preferably 30 µm or less, more preferably 20 µm or less.

The diameter of the fibers constituting the constituent fibers (first fibers 14) on the first surface 10a side of the first layer 11 is preferably 3 µm or more, more preferably 5 µm or more, and preferably 30 µm or less, more preferably 25 µm or less. The diameter of the fibers constituting the constituent fibers (first fibers 14) of the first layer 11 on the side of the second surface 10b is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 25 μm or less, more preferably 20 μm or less

The diameter of the fibers constituting the fibers (second 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.

[0066]

The multilayer structure in the multilayer nonwoven fabric according to the present invention may include, in addition to the hydrophilic first layer and the hydrophobic second layer described above, other layers on the side of the first surface 10a of the first layer 11 or on the side of the second surface 10b of the second layer 12 to such an extent that the effects of the present invention are not impaired. For example, in the multilayer nonwoven fabric 10 illustrated in FIG. 1, a separate layer may be placed on the side of the first surface 10a of the first layer 11. In other words, the multilayer nonwoven fabric 10 may have a multilayer structure with three or more layers, including: a separate layer (not illustrated) defining the first surface 10a; a second layer 12 forming a second surface 10b; and a first layer 11 sandwiched between these two layers.

[0067]

Another embodiment of the multilayer structure in the multilayer nonwoven fabric according to the present invention is a configuration in which the multilayer nonwoven fabric 10 illustrated in FIG. 1 includes elastic members (not illustrated) sandwiched between the first layer 11 and the second layer 12. In cases in which the multilayer structure 13 is a multilayer structure including three or more fibrous layers, as described above, the placement of elastic members is not limited to being placed between the first layer 11 and the second layer 12, and the elastic members may be placed between arbitrary layers of a plurality of fibrous layers. The placement of elastic elements between the layers of the multilayer structure provides elasticity to the multilayer nonwoven fabric and can further expand the scope of the multilayer nonwoven fabric.

[0068]

Elastic elements are stretchable and preferably have the property (elasticity) that when the elastic elements are stretched to a length 1.3 times the original length (that is, to a length of 1.3 times the original length) and the subsequent release of the force in this In the state, the elastic members return to a length that is 1.1 times or less the original length. It should be noted that an inelastic element is an element that does not have this "elasticity" - that is, an element that does not stretch to a length that is 1.3 times or more of the original length, without breaking, or an element that has the property, when which, when it is stretched to a length that exceeds 1.3 times the original length (that is, to a length of 1.3 of the original length) and the subsequent release of the force in this state, the element does not return to a length that exceeds 1.1 times or less than the original length. There is no particular limitation on the shape of the elastic members, and any of various shapes can be arbitrarily selected, such as a thread, a sheet or an elastic fiber bundle (elastic fiber layer). For example, in the multilayer nonwoven fabric 10 (multilayer structure 13) illustrated in FIG. 1, a plurality of filamentary (filament-shaped) elastic members may be interposed between the first layer 11 and the second layer 12 so that they extend in the same direction, in which case the nonwoven laminate 10 (laminate 13) is imparted extensibility in the direction in which the elastic members extend.

[0069]

Another embodiment of the multilayer structure in the multilayer nonwoven fabric according to the present invention is a configuration in which at least one of the first layer 11 and the second layer 12 in the multilayer nonwoven fabric 10 illustrated in FIG. 1 is a sheet that is stretchable in the width direction.

A sheet having extensibility refers to a sheet-like member having the aforementioned "elasticity". A sheet that does not have extensibility refers to a sheet-like member that does not have the aforementioned "elasticity". Examples of embodiments of sheets that can be suitably used include: (1) extensible nonwoven fabrics, in which the stretch fibrous layer is bonded to one or both surfaces of the elastic fibrous layer to form one piece with it; (2) extensible nonwoven fabrics in which the stretch fibrous layer is bonded to one surface or both surfaces of the mesh elastic sheet to form one piece with it; (3) stretch sheets in which a stretch fibrous layer is bonded to one or both surfaces of an elastic sheet of elastic film to form one piece with it, and (4) stretch sheets in which a plurality of elastic filaments / fibers that arranged so that they extend in the same direction without intersecting with each other, bonded to the stretchable nonwoven in a state in which they are substantially not stretched over their entire length.

The use of a sheet having extensibility in the width direction as the first layer 11 and / or the second layer 12 provides elasticity to the multilayer nonwoven fabric and can further expand the scope of the multilayer nonwoven fabric.

[0070]

Natural rubbers or thermoplastic elastomeric polymeric materials can be used as materials for elastic members and elastic filaments in stretchable sheets. Examples of thermoplastic elastomeric polymeric materials include: styrene-based elastomers such as interleaved styrene-butadiene block copolymer (SBS), styrene-isoprene interleaved block copolymer (SIS), styrene-ethylene-butadiene interlaced block copolymer blocks (SEBS) and interleaved styrene / ethylene-propylene block copolymer (SEPS); olefin-based elastomers (eg, ethylene-based α-olefin elastomers and propylene-based elastomers obtained by copolymerizing ethylene, butene, octane, etc.); polyester elastomers and polyurethane elastomers.

[0071]

Next, a preferred embodiment of the method for manufacturing the multilayer nonwoven fabric of the present invention will be described with reference to the drawings. FIG. 4 schematically illustrates an embodiment of a method for manufacturing a multilayer nonwoven fabric.

[0072]

As illustrated in FIG. 4, the present manufacturing method includes: an overlaying step of obtaining a multilayer element 10P by moving the base sheet 11P and laying on the movable base sheet 11P fibers (second fibers 15), amenable to fusion bonding, which are long fibers obtained by molding resin, and the step of bonding the layers to each other, which is to squeeze the multilayer member 10P in some portions in the thickness direction and heat the multilayer member 10P to form the interlayer bonded portions 16.

[0073]

More specifically, the base sheet 11P, which is wound in a roll, is unwound and transported by the conveyor 50 in one direction indicated by the reference numeral MD. During the movement, the second fibers 15 are molded out of the die of the forming head 51 located above the conveyor 50 and are stacked directly on the base sheet 11P to form the laminate 10P thereby. The spun second fibers 15 are fusion-bonding fibers that are long fibers. The laminated element 10P continues to move and is fed between two embossing rollers 52 and 53, in which the laminated element 10P is hot-embossed to form the interlayer bonded portions 16 therewith (the step of joining the layers together). An embossing roll 52 is positioned above the movable laminate 10P and, during hot embossing, contacts a stack (web) of continuous straight-spun second fibers 15. An embossing roller 53 is located under the movable laminate 10P and contacts the base sheet 11P during hot stamping. The outer circumferential surface of the embossing roller 53 has no protrusions and depressions, while the outer circumferential surface of the embossing roller 52 has protrusions (not illustrated) formed in a configuration that matches the configuration of the interlayer connected portions 16. Through the clamping portion between the rollers 52 and 53 for embossing having the above configuration, the multilayer member 10P is compressed in the thickness direction while being heated to a temperature equal to or higher than the melting point of the second fibers 15 included in the multilayer member, and thereby the multilayer member 10P is compressed in some parts by the roll projections 52 for embossing from the side on which the second fibers 15 are laid toward the side of the base sheet 11P, and thereby interlayer bonded portions 16 are formed in the pressed portions. Thus, the stack of second fibers 15 is converted into a nonwoven fabric forming the second layer 12 and is integrally integrated with the base sheet 11P by the interlayer bonded portions 16. In addition, the second fibers 15 are included in the base sheet 11P. In other words, the molten constituent fibers (second fibers) pass between the constituent fibers of the first layer (i.e., base sheet 11P), retaining their fiber shape, and solidify.

[0074]

The multilayer nonwoven fabric of the present invention encompasses configurations in which a plurality of second layers 12 are superimposed on each other to form a multilayer structure 13 having three or more layers. A multilayer nonwoven fabric having such a configuration can be produced simply by laying the second fibers 15 multiple times on the base sheet 11P in the step of producing the multilayer member 10P. For example, in the above manufacturing method, a plurality of forming heads 51 may be spaced in the MD conveyance direction, and the second fibers 15 may be sequentially formed by the forming heads 51.

[0075]

For the formation of the first layer 11, it is preferable that the base sheet 11P is a nonwoven fabric formed mainly by fibers that are not amenable to fusion bonding. Examples of such nonwoven fabrics include: nonwoven fabrics made by mixing non-fusion-bonding fibers with fusion-bonding fibers; composite nonwovens made by applying non-fusion-bonded fibers to a fusion-bonding nonwoven or by subjecting non-fusion-bonding fibers to papermaking processes on a fusion bonded nonwoven and nonwovens including into densified portions which have a higher density than portions peripheral to them and in which constituent fibers (first fibers 14) are densified together. More preferably, the base sheet 11P is a nonwoven fabric made up of mainly hydrophilic fibers that are not fusion bonded.

The base sheet 11P can be manufactured according to a conventional method depending on the type of the base sheet 11P. More specifically, the base sheet 11P can be made by a webbing step by stacking the fibers, for example, by carding, and a densification step such as embossing, forming densified portions by compressing the web in some portions in the thickness direction. Alternatively, the base sheet may be made by a known nonwoven fabrication method, such as hydroentangling or needling, which does not include a densification step.

[0076]

The fibers constituting the base sheet 11P material may be subjected to the above hydrophilic treatment to render the base sheet 11P hydrophilic. In this case, the hydrophilicity treatment is carried out at least before the second fibers 15 are directly stacked. Any of the aforementioned coating methods can be used in cases where the hydrophilic treatment is performed by applying a hydrophilizing agent.

[0077]

In the present manufacturing method, it is preferable to subject the multilayer element 10P (multilayer nonwoven fabric 10) to a calendering process before or after the step of bonding the layers together. Thus, this will further assist in introducing the second fibers 15 into the base sheet 11P, and thus various properties of the multilayer nonwoven fabric 10 such as liquid wicking and strength can be further improved. As is well known in the art, the calendering process is the process of applying heat and applying pressure through calendering rollers to a fiber bundle, such as a nonwoven fabric, to strongly seal the fiber bundle. There is no particular limitation on the number and pattern of calender rolls to be used in the calendering process, examples used include: sequential or tilted configuration of three calender rolls, sequential, inverted L, Z configuration -shaped or oblique Z-shaped, formed by four calender rollers, and a configuration with Z-shaped or L-shaped, formed by five calender rollers. The temperature in the calendering process is preferably equal to or less than the softening temperature of the constituent fibers of the multilayer element 10P (multilayer nonwoven fabric 10) to be treated. Carrying out the calendering process at a temperature above the softening point may cause the nonwoven fabric to become stiff, which degrades the texture to the touch.

[0078]

In addition, the base sheet 11P may be subjected to a calendering process before the laminate 10P is formed. Thus, the interfiber spacing in the base sheet 11P decreases and the capillary pressure increases, thereby increasing the ability to absorb liquids. This achieves the effect that the side of the second surface 10b remains dry even after the liquid has been absorbed, even in cases where the hydrophobic second layer has a relatively large interfiber spacing and a low basis weight. Briefly, it can be pointed out that the calendering process in this manufacturing method can be carried out immediately before the step of bonding the layers to each other or immediately after the step of bonding the layers to each other and / or before laying the second fibers 15 on the base sheet 11P.

[0079]

The calendering process can be used in the step of making the base sheet 11P. More specifically, the precursor material of the base sheet 11P may be subjected to a calendering process immediately prior to the densification step or immediately after the densification step.

[0080]

As described above, the multilayer nonwoven fabric of the present invention encompasses configurations in which elastic members having any of various shapes, such as a thread, sheet, or elastic fiber bundle (elastic fiber layer), are sandwiched between the first layer and the second layer. In cases of manufacturing a multilayer nonwoven fabric configured with elastic elements between the layers of the multilayer structure, the elastic elements simply need to be fed onto the base sheet 11P before laying the second fibers 15 on the base sheet 11P. The method of placing the elastic elements can be appropriately selected depending, for example, on the shape of the elastic elements. For example, in cases where the elastic to be placed is a layer of elastic fibers, which is an accumulation of elastic fibers, the elastic fibers can be continuously formed and fed directly onto the base sheet 11P like the second fibers 15.

[0081]

The absorbent article of the present invention is described below in accordance with preferred embodiments with reference to the drawings. The absorbent article of the present invention is characterized in that it includes the aforementioned multilayer nonwoven fabric. More specifically, as described above, the multilayer nonwoven fabric according to the present invention has a multilayer structure in which a plurality of fibrous layers are superimposed on each other, and the multilayer structure has a first surface forming one surface of the multilayer nonwoven fabric and a second surface forming another surface, and the multilayer nonwoven fabric includes a hydrophilic first layer forming a first surface and a hydrophobic second layer located on the side of the second surface relative to the first layer. In the absorbent article of the present invention, the nonwoven laminate is positioned with the second surface facing the skin side of the wearer.

[0082]

FIG. 5-7 illustrate a pull-on disposable diaper 1, which is an embodiment of an absorbent article of the present invention. The following description of the diaper 1 will mainly be directed to constituent members different from the constituent members in the above multilayer nonwoven fabric 10, which is an embodiment of a multilayer nonwoven fabric; constituent elements that are the same are denoted by the same reference numerals, and their explanation is omitted. The explanation regarding the multilayer nonwoven fabric 10 is appropriately valid for constituent members that are not specifically described.

[0083]

As illustrated in FIG. 5 and 6, the diaper 1 includes in the longitudinal direction X a front area A, a back area B, and a crotch area C located between areas A and B. The diaper includes an absorbent member 23 extending between the front area A and the back area B, and further includes a front waist flap FA and a rear waist flap FB, which are located outside, respectively, of the respective front and rear portions 23A and 23B of the absorbent member 23, end in the longitudinal direction X, and each of which extends in the side direction Y. Here In case, front area A is an area that is located on the front side of the wearer when an absorbent article such as a disposable diaper is worn, and back area B is an area that is located on the back side of the wearer when an absorbent article such as a disposable diaper is worn. The front area A and the back area B form a waist / hip portion corresponding to the waist / hips of the wearer when wearing the diaper 1.

[0084]

As illustrated in FIG. 6, the front waist flap FA refers to a zone formed from a zone that is located outside in the longitudinal direction X from the edge of the front portion 23A of the absorbent member 23, end in the longitudinal direction X and located on the side of the front zone A and which extends in the lateral direction Y , and an area that extends in the lateral direction Y from the front part 23A of the absorbent member 23, end in the longitudinal direction X and located on the side of the front area A. The rear waist flap FB refers to the area formed from the area that is located outside in the longitudinal direction X from the edge of the rear portion 23B of the absorbent body 23, end in the longitudinal direction X and located on the side of the rear area B and which extends in the lateral direction Y, and the area that extends in the lateral direction Y from the rear portion 23B of the absorbent body 23, end in the longitudinal direction direction X and located on the side of the rear zone B.

[0085]

As illustrated in FIG. 5 and 6, the diaper 1 includes an absorbent assembly 2 and an outer cover 3, which is located on the non-skin side of the absorbent assembly 2, and to which the absorbent assembly 2 is attached. The outer cover 3 includes a front waist flap FA and a rear waist flap FB, which are respectively located outside the respective longitudinal end X front and rear portions 23A and 23B of the absorbent member 23 constituting the absorbent assembly 2 and which extend in the lateral direction Y. In the diaper 1, an elasticized zone (waist elasticized part G1 and below the waist, elasticized part G2) are formed in each of the front waist flap FA and the rear waist flap FB.

[0086]

As illustrated in FIG. 6, the diaper 1 is a so-called pull-on disposable diaper (see Fig. 5), in which two side seams S and S, a waist opening WO and two leg openings LO and LO are formed by joining both left and right , the side edge portions 3a1 and 3a1 of the outer cover 3 in the front region A together with both left and right side edge portions 3b1 and 3b1 of the outer cover 3 in the rear region B. As illustrated in FIG. 6, in a plan view of the diaper 1 in a straightened and stretched state, the outer cover 3 of the diaper 1 is preferably divided into a front area A to be placed on the front side of the wearer when worn, a rear area B to be placed on the back of the wearer when worn, and the crotch area C located between the front area A and the back area B. In this document, the "expanded and stretched state of the diaper 1" refers to the state in which the side seams S are torn to bring the diaper 1 into an expanded (unfolded) state and elastic elements in different parts of the expanded diaper 1 are stretched so that the diaper will be expanded to its calculated size (the size when the diaper is flattened out in a state in which the effect of the elastic members is completely removed), as illustrated in FIG. 6.

[0087]

As used herein, "skin-facing surface" refers to the surface of the diaper 1 or its constituent element (eg, absorbent assembly 2) facing the skin side of the wearer when the diaper is being worn, while "non-skin-facing surface" refers to the surface of the diaper 1 or a component thereof, which faces the side (i.e., the side of the garment) opposite to the wearer's skin when the diaper is being worn. In the diaper 1, the longitudinal direction X is a direction corresponding to a direction extending from the front side of the wearer to the back side through the crotch portion, and is a direction extending from the front area A to the back area B when the diaper 1 is unfolded and stretched flat. The lateral direction Y is a direction orthogonal to the longitudinal direction X and is a width direction of the diaper 1 when it is unfolded and stretched flat. The diaper 1 has left-right symmetry about the longitudinal center line CL1 extending in the longitudinal direction X, as illustrated in FIG. 6. In FIG. 6, reference numeral CL2 denotes a transverse centerline that extends in the lateral direction Y, bisects the diaper 1 and is orthogonal to the longitudinal centerline CL1.

[0088]

As illustrated in FIG. 6, in the diaper 1, the absorbent assembly 2 has an elongated shape that is relatively long in the longitudinal direction X when the diaper 1 is in the unfolded and stretched state. The absorbent assembly 2 includes a liquid-permeable topsheet 21 defining a skin-facing surface, a minimally liquid-permeable (or water-repellent) backsheet 22 defining a non-skin-facing surface and retaining liquids, an absorbent element 23 disposed between the sheets 21 and 22. Also, as illustrated in FIG. 6, both sides of the absorbent assembly 2 that extend along the longitudinal direction X (length direction) are respectively provided with leakage cuffs 24 and 24, each of which includes elastic members disposed in a state in which they are stretched longitudinal direction X. More specifically, each anti-leakage cuff 24 is formed of an air-permeable and minimally liquid-permeable / water-repellent material, and in the vicinity of the free end of each anti-leakage sleeve 24, elastic members 25 forming the anti-leakage sleeve, placed in a state in which they are stretched in the longitudinal direction X. When the diaper is worn, the tightening of the elastic members 25 forming the leakage cuffs causes the side corresponding to the free end of both leakage cuffs 24 to rise, thus preventing the leakage medium in the lateral direction Y.

[0089]

As illustrated in FIG. 6, the absorbent assembly 2 having the above-described configuration is attached by means of an adhesive for fixing the assembly to the center portion of the outer cover 3 so that the longitudinal direction of the absorbent assembly corresponds to the longitudinal direction X of the diaper 1 in the expanded and stretched state. As described above, with respect to the thickness direction of the disposable diaper 1, the outer cover 3 is disposed on the non-skin-facing surface of the backsheet 22 forming the absorbent assembly 2, and is attached / attached to the non-skin-facing surface of the backsheet 22. Thus , in the diaper 1, the absorbent member 23 forming the absorbent assembly 2 is positioned to extend between the front area A and the rear area B.

[0090]

As illustrated in FIG. 6, in the diaper 1, the outer cover 3 includes a front waist flap FA and a rear waist flap FB, which are respectively located outside in the longitudinal direction X from the respective front and rear end portions 23A and 23B of the absorbent member 23 and which extend in the lateral direction Y. In addition, as illustrated in FIG. 5-7, the outer cover 3 includes an outer sheet 6 on the non-skin surface side forming the outer surface of the diaper 1, and an inner sheet 3i located on the skin-facing surface of the outer sheet 6. The outer sheet 6 has a folded portion 6R formed by folding a projection of the outer sheet protruding from the longitudinally-defined front or rear end of the inner sheet 3i towards the skin-facing surface of the inner sheet 3i. As illustrated in FIG. 6, the folded portion 6R of the outer sheet 6 is formed with a rectangular shape elongated in the lateral direction Y. Each of the front and rear end portions 23A and 23B of the absorbent assembly 2 is covered by the folded portion 6R.

[0091]

As described above, the diaper 1 includes a front area A and a back area B as a waist / hip portion that matches the waist / hips of the wearer when the diaper is worn. As illustrated in FIG. 6, zones A and B each include at least a waist elasticized portion G1 and an elasticized portion G2 below the waist, formed as an elasticized zone. In addition, elasticized leg portions G3 can be formed. More specifically, the outer cover 3 includes, in each of the regions A and B, a plurality of elastic members 71 provided between the outer sheet 6 and the inner sheet 3i forming the outer cover 3, the elastic members being provided in a state in which they are stretched in the lateral direction Y, and spaced apart in the longitudinal direction X. Thus, the waist elasticized portion G1 and below the waist, elasticized portion G2 are formed as an elasticized zone having extensibility in the lateral direction Y in each of the zones A and B. In addition, the outer cover 3 includes a plurality of leg elastic members 72 extending from each of the areas A and B to the crotch area C and provided between the outer sheet 6 and the inner sheet 3i in a state in which the elastic members 72 are stretched in a predetermined direction. Thus, the elasticized portions G3 for the legs can be formed as an elasticized zone in zones A, B and C.

[0092]

In the diaper 1 illustrated in FIG. 5 and 6, the waist elasticized portion G1 is formed in a flap, end in the longitudinal direction X, which is located further outwardly in the longitudinal direction X (i.e. on the side opposite to the transverse center line CL2) than the edge of each of the end in the longitudinal direction X, the front and rear portions 23A and 23B of the absorbent member 23 forming the absorbent assembly 2. In addition, in the diaper 1 below the waist, elasticized portion G2 is formed in side flaps located in the longitudinal direction X between the lower end of the waist elasticized portion G1 located from the side of the transverse centerline CL2, and the corresponding lower ends of the side seams S. Each of the aforementioned rear waist flap FB and front waist flap FA also constitutes an area formed of an end flap (waist elasticized portion G1) and a portion of side flaps (located below the waist , elasticized part G2). Moreover, in the diaper 1 illustrated in FIG. 5 and 6, an elasticized leg portion G3 is formed along the peripheral edge portion of each leg opening LO.

[0093]

As illustrated in FIG. 5-7, the diaper 1 includes a sweat absorbent sheet 10 (see FIG. 1) capable of absorbing sweat. This sweat-absorbent sheet 10 is a multilayer nonwoven fabric 10, which is the aforementioned embodiment of the multilayer nonwoven fabric according to the present invention. The sweat sheet 10 is positioned so that the second surface 10b (the outer surface of the hydrophobic second layer 12) faces the skin side of the wearer.

[0094]

In the diaper 1, the sweat absorbent sheet 10 is designed to absorb sweat mainly in the waist / hip area of the wearer and is located in the above-mentioned waist / hip portion. More specifically, the sweat-absorbent sheet 10 is disposed in the elasticized region of the waist / hip portion. That is, the sweat-absorbent sheet 10 has a shape that is elongated — more specifically, rectangular (continuous) —in one direction in a plan view, as illustrated in FIG. 6 is located on the entire length of each of the front area A and the rear area B forming the waist / hip portion, the length direction of the sheet corresponding to the lateral direction Y, and is located so that it covers at least at least the elasticized waist part G1 and the elasticized part G2 located below the waist. In more detail, the absorbent sheet 10 is bonded to the skin-facing surface of the folded portion 6R of the outer sheet 6 by a known bonding means such as an adhesive, heat seal, or ultrasonic seal. The folded portion 6R is located closer to the skin of the wearer than the absorbent member 23 when wearing the diaper 1 (see Fig. 7), and thus the sweat absorbent sheet 10 disposed on the skin-facing surface of the folded portion 6R will be located closer to the skin than the absorbent element 23 when wearing the diaper 1 and therefore can come into contact with the wearer's skin.

[0095]

In the diaper 1 having the above configuration, a sweat absorbent sheet 10 (multilayer nonwoven fabric 10) having a sweat absorbing function is located closest to the skin of the wearer wearing the diaper 1 on the skin-facing side of each of the front area A and the rear area B, forming a waist / hip portion, and the area in which the absorbent sheet 10 is located is an elasticized area that includes an elasticized waist portion G1 and an elasticized portion G2 below the waist and has extensibility in the lateral Y direction. When wearing the diaper 1, the contraction caused by the tightening force created by the elasticized zone allows the hydrophobic second surface 10b (see Fig. 1) of the absorbent sheet 10 to contact the wearer's skin with very good fit and the ability to quickly absorb sweat from the skin. In addition, even after absorbing sweat, the sheet does not become sticky and has a very good texture to the touch. Thus, the absorbent sheet 10 (multilayer nonwoven fabric 10) can be suitably used as a sheet for an absorbent article.

[0096]

As described above, in the diaper 1, the absorbent sheet 10 (multilayer nonwoven fabric 10) is disposed in the elasticized region, and therefore, for reasons of increasing the wearer's skin adhesion, it is preferable that the absorbent sheet 10 also has extensibility in the same direction, as the elasticized zone, i.e. in the lateral direction Y. For these reasons, it is preferable that an elastic element (stretch element) having extensibility in the lateral direction Y is placed between the first layer 11 and the second layer 12 of the absorbent sheet 10. The elastic element is is an elastic element like the one described above.

[0097]

Materials for forming the various parts of the diaper 1 are described below. For the topsheet 21, backsheet 22, absorbent member 23, leakage cuffs 24, etc. forming the absorbent assembly 2, various types of materials can be used without particular limitation. commonly used in absorbent articles such as disposable diapers. For example, the topsheet 21 can be used, for example, a non-woven fabric with a single or multi-layer structure or a porous film. For the backsheet 22, for example, a liquid-permeable polymer film can be used. For the absorbent member 23, an absorbent core made of absorbent polymer particles and fibrous materials can be used, with the absorbent core covered with tissue paper. For the leakage cuffs 24, for example, a water-repellent nonwoven fabric with a single or multi-layer structure can be used. For various elastic elements (elastic elements 25 forming leakage cuffs, elastic elements 71, elastic elements 72 for legs, etc.), for example, synthetic rubber such as styrene butadiene, butadiene, isoprene or neoprene, natural rubber, ethylene vinyl acetate copolymer (EVA), extensible polyolefins or polyurethane. With regard to the shapes of the elastic elements, it is preferable to use filamentary elements (rubber threads) having a rectangular, square, circular, elliptical or polygonal cross-sectional shape, or ribbon-like elements (rubber bands). One of various types of adhesives can be used as the bonding means that bonds the constituent elements of the diaper 1 together, such as a hot melt adhesive commonly used for these types of absorbent articles.

[0098]

The present invention has been described above in accordance with its embodiments, but the present invention is not limited to the above embodiments, and may be modified accordingly.

For example, in a diaper 1, the nonwoven laminate 10 is used as the absorbent sheet, but the nonwoven laminate 10 can be used in the absorbent article of the present invention as a different constituent element other than the absorbent sheet, provided that the second surface (hydrophobic surface, having interlayer connected parts) is positioned so that it faces the skin side of the wearer. Even in cases where the multi-layer nonwoven fabric is used as a sweat-absorbent sheet, the location of the sheet is not limited to the location where the sweat-absorbent sheet 10 is located in the diaper 1. An example of another use of the multi-layer nonwoven fabric is its use as a topsheet that is closer to the wearer's skin than the absorbent. That is, in the diaper 1, the nonwoven laminate 10 can be used as the topsheet 21. Thus, the nonwoven laminate 10 can be used appropriately as a sheet for an absorbent article.

[0099]

As illustrated in FIG. 6, the outer cover 3 of the diaper 1 includes elastic members 71 interposed between the outer sheet 6 and the inner sheet 3i, but elastic members 71 need not be provided. In cases where the elasticized region without elastic members 71 is formed, the stretchable nonwoven fabric having the ability to stretch in the lateral direction Y can be used as a component of the outer cover 3.

As illustrated in FIG. 6, in the diaper 1, the outer cover 3 has a continuous shape and extends through the front area A, the crotch area C and the rear area B, but instead the outer cover 3 may be shaped in which the outer cover 3 is divided into the front outer cover to be placed on the front side of the wearer, and a rear outer cover to be placed on the back side of the wearer. Alternatively, the outer cover 3 may be shaped in which the outer cover 3 is divided into a front outer cover, a rear outer cover, and a crotch outer cover positioned between the front outer cover and the rear outer cover. In cases in which the outer cover 3 has a split shape, the above multilayer nonwoven fabric is preferably included in at least one of the front outer cover and the rear outer cover, more preferably at least the rear outer cover.

The absorbent article according to the present invention is not limited to a pull-on disposable diaper like the aforementioned diaper 1, but is also applicable in general to articles that are used to absorb body fluids, and is applicable, for example, to open-type disposable diapers and sanitary napkins.

The use of the absorbent sheet of the present invention is not limited to the above-mentioned absorbent articles, but can be applied to articles other than absorbent articles. For example, the sweat-absorbent sheet of the present invention can be used as is as a sheet used by a user to wipe off sweat. Other uses include insoles for soles, underarm pads for wicking sweat, eye masks and face masks; by positioning the absorbent sheet of the present invention so that it faces the skin side of the wearer, sweat from the soles, underarms or face can be quickly absorbed. In addition, the application for face masks, etc., which are kept in contact with the skin even after absorbing sweat, prevents adhesion to the skin and provides an excellent texture to the touch.

With respect to the above embodiments of the present invention, the following additional features are also disclosed.

[0100]

{1} An absorbent article comprising a multilayer nonwoven fabric having a multilayer structure in which a plurality of fibrous layers are superimposed on each other, wherein:

the multilayer nonwoven fabric has a first surface defining one surface and a second surface defining another surface, and the multilayer nonwoven fabric includes a hydrophilic first layer defining a first surface and a hydrophobic second layer located on the second surface side relative to the first layer;

the first layer includes fibers that are not amenable to fusion bonding;

the second layer is mainly formed by fusion-bonding fibers, which are long fibers;

the multilayer nonwoven fabric includes, in some portions in a plan view of the multilayer nonwoven fabric, interlayer bonded portions in which the layers forming the multilayer structure are bonded together, each of the interlayer bonded portions being thinner than the peripheral portion;

a portion including the interlayer bonded portion is recessed from the second surface side towards the first surface side;

the constituent fibers of the first layer in the interlayer bonded portion are stored as fibers;

the constituent fibers of the second layer in the interlayer bonded portion are melted, and a portion of the molten resin constituent passes between the constituent fibers of the first layer and solidifies;

the multilayer nonwoven fabric is positioned with the second surface facing the skin side of the wearer; and

The absorbent article includes a waist / hip portion corresponding to the waist / hips of the wearer, and a multilayer nonwoven fabric is disposed in the waist / hip portion.

[0101]

{2} The absorbent article according to item {1}, wherein, in the portion overlapping the interlayer bonded portion in the thickness direction of the multilayer nonwoven fabric, the first layer has a portion into which the molten resin constituent of the second layer has entered and a portion that does not include the molten constituent resin.

{3} Absorbent article according to {1} or {2}, in which:

the second layer includes, in some portions, in a plan view of the multilayer nonwoven fabric, fused bonded portions in which the fusion-bonded fibers are bonded together; and

the fused bonded portions form part of the second layer in the corresponding interlayer bonded portion.

{4} An absorbent article according to any one of items {1} to {3}, wherein:

the absorbent article includes an elasticized area in the waist / hip portion; and

multilayer nonwoven fabric is located in the elasticized area.

{5} An absorbent article according to any one of items {1} to {4}, wherein:

an absorbent article includes a liquid-retaining absorbent member; and

the multilayer nonwoven fabric is located closer to the skin of the wearer than the absorbent body.

{6} An absorbent article according to any one of items {1} to {5}, wherein:

an absorbent article includes an absorbent assembly including a liquid storage, an absorbent member, and an outer cover attached to the non-skin side of the surface of the absorbent assembly;

the outer cover includes a front outer cover to be placed on the front side of the wearer and a rear outer cover to be placed on the rear side;

at least the rear outer cover includes a multilayer nonwoven fabric; and

the multilayer nonwoven fabric is positioned with the second surface facing the skin side of the wearer.

{7} An absorbent article according to any one of items {1} to {6}, wherein the combined basis weight of the first layer and the second layer of the multilayer nonwoven fabric is preferably 11 g / m ² or more, more preferably 14 g / m ² or more, and preferably 55 g / m ² or less, more preferably 50 g / m ² or less.

{8} An absorbent article according to any one of items {1} to {7}, wherein the first layer of the multilayer nonwoven fabric has a basis weight of 8 to 40 g / m ² .

{9} An absorbent article according to any one of items {1} to {8}, wherein the basis weight of the first layer of the multilayer nonwoven fabric is preferably 8 g / m ² or more, more preferably 11 g / m ² or more, and preferably 40 g / m ² or less, more preferably 35 g / m ² or less.

{10} An absorbent article according to any one of items {1} to {9}, wherein the second layer of the multilayer nonwoven fabric has a basis weight of 3 to 25 g / m ² .

[0102]

{11} An absorbent article according to any one of items {1} to {10}, in which the basis weight of the second layer of the multilayer nonwoven fabric is preferably 3 g / m ² or more, more preferably 5 g / m ² or more, and preferably 25 g / m ² or less, more preferably 15 g / m ² or less, even more preferably 13 g / m ² or less.

{12} An absorbent article according to any one of items {1} to {11}, wherein:

the total area of the interlayer bonded portions of the multilayer nonwoven fabric is 15% or less of the total area of the multilayer nonwoven fabric; and

the area of one interlayer bonded portion is 1 mm ² or less.

{13} An absorbent article according to any one of items {1} to {12}, wherein the percentage of area of interlayer bonded portions is preferably 5% or more, more preferably 6% or more, and preferably 15% or less, more preferably 12 % or less.

{14} An absorbent article according to any one of items {1} to {13}, wherein the area of one interlayer bonded portion on the second surface is preferably 0.1 mm ² or more, more preferably 0.15 mm ² or more, and preferably 1 mm ² or less, more preferably 0.8 mm ² or less.

{15} An absorbent article according to any one of items {1} to {14}, wherein:

the first layer of the multilayer nonwoven fabric is mainly formed by fibers that are not amenable to fusion bonding; and

fibers that are not amenable to fusion bonding constitute at least 50% of the constituent fibers of the first layer.

{16} An absorbent article according to any one of items {1} to {15}, wherein the non-fusion-bonding fibers are natural fibers, cellulose hydrated fibers, or semi-synthetic fibers.

{17} An absorbent article according to any one of items {1} to {16}, wherein the non-fusion-bonding fibers are short fibers.

{18} An absorbent article according to any one of items {1} to {17}, wherein the constituent fibers of the first layer have a shorter interfiber spacing than the second layer.

{19} The absorbent article according to {18}, wherein the ratio (L2 / L1) between the inter-fiber distance L1 between the constituent fibers of the first layer and the inter-fiber distance L2 between the constituent fibers of the second layer is preferably 1.1 or more, more preferably 10 or more and preferably 70 or less, more preferably 50 or less.

{20} The absorbent article according to {18} or {19}, wherein the interfiber distance L1 between the constituent fibers of the first layer is preferably 5 µm or more, more preferably 7 µm or more, and preferably 100 µm or less, more preferably 80 µm or less.

[0103]

{21} An absorbent article according to any one of items {18} to {20}, wherein the inter-fiber distance L2 between constituent fibers of the second layer is preferably 7 μm or more, more preferably 10 μm or more, and preferably 200 μm or less, more preferably 150 μm or less.

{22} An absorbent article according to any one of items {1} to {21}, wherein the constituent fibers of the first layer of the multilayer nonwoven fabric have a smaller fiber diameter than constituent fibers of the second layer.

{23} The absorbent article according to {22}, in which the ratio (D1 / D2) of the diameter D1 of the fibers constituting the first layer fibers to the diameter D2 of the fibers constituting the second layer fibers is preferably 0.05 or more, more preferably 0.06 or more, and preferably 0.9 or less, more preferably 0.8 or less.

{24} The absorbent article according to {22} or {23}, wherein the diameter D1 of the fibers constituting the fibers of the first layer is preferably 0.5 µm or more, more preferably 1 µm or more, and preferably 30 µm or less, more preferably 20 µm or less.

{25} An absorbent article according to any one of items {22} to {24}, wherein the diameter D2 of the fibers constituting the fibers of the second layer is preferably 3 µm or more, more preferably 5 µm or more, and preferably 40 µm or less, more preferably 30 µm or less.

{26} An absorbent article according to any one of items {1} to {25}, wherein the constituent fibers of the first layer of the nonwoven laminate on the second surface side have a higher degree of hydrophilicity than the constituent fibers on the first surface of the first layer.

{27} An absorbent article according to any one of items {1} to {26}, wherein the constituent fibers on the second surface side of the first layer of the multilayer nonwoven fabric have a shorter interfiber spacing than the constituent fibers on the first surface of the first layer.

{28} The absorbent article of {27}, wherein the inter-fiber distance L1a between the constituent fibers on the first surface side of the first layer is preferably 10 µm or more, more preferably 15 µm or more, and preferably 100 µm or less, more preferably 80 µm or less.

{29} The absorbent article according to {27} or {28}, wherein the interfiber distance L1b between the constituent fibers of the first layer on the second surface side is preferably 5 µm or more, more preferably 7 µm or more, and preferably 80 µm or less, more preferably 70 microns or less.

{30} An absorbent article according to any one of items {1} to {29}, wherein the constituent fibers of the first layer on the second surface side have a smaller fiber diameter than the constituent fibers on the first surface of the first layer.

[0104]

{31} The absorbent article of {30}, wherein the diameter of the fibers constituting the fibers on the first surface side of the first layer is preferably 3 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 25 μm or less.

{32} An absorbent article according to {30} or {31}, wherein the diameter of the fibers constituting the fibers of the first layer on the second surface is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 25 μm or less, more preferably 20 µm or less.

{33} An absorbent article according to any one of items {1} to {32}, wherein an elastic member is sandwiched between a plurality of fibrous layers of a nonwoven laminate.

{34} An absorbent article according to any one of items {1} to {33}, wherein one or both of the first layer and the second layer of the nonwoven laminate is / is stretchable in a width direction orthogonal to the longitudinal direction of the absorbent article.

{35} The absorbent article according to any one of items {1} to {34}, in which the first layer includes at least 50% of the mass. hydrophilic fibers.

{36} The absorbent article according to any one of items {1} to {35}, in which the second layer is formed mainly by hydrophobic fibers and includes at least 90% of the mass. hydrophobic fibers.

{37} An absorbent article according to any one of items {1} to {36}, wherein:

the contact angle of the constituent fibers of the second layer is greater than the contact angle of the constituent fibers of the first layer; and

the contact angle of the constituent fibers of the second layer is preferably 95 degrees or more, more preferably 100 degrees or more, and preferably 150 degrees or less, more preferably 130 degrees or less.

{38} An absorbent article according to any one of items {1} to {37}, wherein:

the contact angle of the constituent fibers of the first layer is less than the contact angle of the constituent fibers of the second layer; and

the contact angle of the constituent fibers of the first layer is preferably 5 degrees or more, more preferably 10 degrees or more, and preferably 88 degrees or less, more preferably 85 degrees or less.

{39} An absorbent article according to any one of items {1} to {38}, wherein:

besides the interlayer bonded portions, the first layer includes densified parts formed by strongly densifying / increasing the density of the constituent fibers of the first layer, each of the densified parts having a smaller thickness than the peripheral part; and

the area of one sealed portion is preferably 0.1 mm ² or more, more preferably 0.15 mm ² or more, and preferably 1 mm ² or less, more preferably 0.8 mm ² or less.

[0105]

{40} Absorbent sheet having a multilayer structure in which a plurality of fibrous layers are superimposed on each other, wherein the absorbent sheet has a first surface and a second surface located on the side opposite to the first surface, wherein the absorbent sheet is used for the second surface facing the skin side of the wearer, wherein the sweat absorbent sheet comprises:

hydrophilic first layer forming the first surface; and

a hydrophobic second layer located on the side of the second surface relative to the first layer, while:

the first layer includes fibers that are not amenable to fusion bonding;

the second layer is mainly formed by fusion-bonding fibers, which are long fibers;

the sweat-absorbent sheet includes, in some portions in a plan view of the sweat-absorbent sheet, interlayer bonded portions in which the layers forming the multilayer structure are bonded together, each of the interlayer bonded portions having a smaller thickness than the peripheral portion;

a portion including the interlayer bonded portion is recessed from the second surface side towards the first surface side;

the constituent fibers of the first layer in the interlayer bonded portion are stored as fibers; and

the constituent fibers of the second layer are melted in the interlayer bonded portion, and a portion of the molten resin constituent passes between the constituent fibers of the first layer and solidifies.

Industrial applicability

[0106]

In accordance with the present invention, there is provided an absorbent article and a sweat-absorbent sheet that are unlikely to cause rewetting and that have very good ability to absorb body fluids such as sweat and urine.

Claims (51)

1. An absorbent article comprising a multilayer nonwoven material having a multilayer structure in which a plurality of fibrous layers are superimposed on each other, wherein: the multilayer nonwoven fabric has a first surface defining one surface and a second surface defining another surface, and the multilayer nonwoven fabric includes a hydrophilic first layer defining a first surface and a hydrophobic second layer located on the second surface side relative to the first layer; the first layer includes fibers that are not amenable to fusion bonding; the second layer is mainly formed by fusion-bonding fibers, which are long fibers; the multilayer nonwoven fabric includes, in some portions in a plan view of the multilayer nonwoven fabric, interlayer bonded portions in which the layers forming the multilayer structure are bonded together, each of the interlayer bonded portions being thinner than the peripheral portion; a portion including the interlayer bonded portion is recessed from the second surface side towards the first surface side; the constituent fibers of the first layer in the interlayer bonded portion are stored as fibers; the constituent fibers of the second layer in the interlayer bonded portion are melted, and a portion of the molten resin constituent passes between the constituent fibers of the first layer and solidifies; the multilayer nonwoven fabric is positioned with the second surface facing the skin side of the wearer; the absorbent article includes a waist / hip portion corresponding to the waist / hips of the wearer, and a multilayer nonwoven fabric is positioned in the waist / hip portion; and the constituent fibers of the first layer of the multilayer nonwoven fabric from the second surface have a higher degree of hydrophilicity than the constituent fibers of the first layer from the first surface. 2. An absorbent article containing a multilayer nonwoven material having a multilayer structure in which a plurality of fibrous layers are superimposed on each other, wherein: the multilayer nonwoven fabric has a first surface defining one surface and a second surface defining another surface, and the multilayer nonwoven fabric includes a hydrophilic first layer defining a first surface and a hydrophobic second layer located on the second surface side relative to the first layer; the first layer includes fibers that are not amenable to fusion bonding; the second layer is mainly formed by fusion-bonding fibers, which are long fibers; the multilayer nonwoven fabric includes, in some portions in a plan view of the multilayer nonwoven fabric, interlayer bonded portions in which the layers forming the multilayer structure are bonded together, each of the interlayer bonded portions being thinner than the peripheral portion; a portion including the interlayer bonded portion is recessed from the second surface side towards the first surface side; the constituent fibers of the first layer in the interlayer bonded portion are stored as fibers; the constituent fibers of the second layer in the interlayer bonded portion are melted, and a portion of the molten resin constituent passes between the constituent fibers of the first layer and solidifies; the multilayer nonwoven fabric is positioned with the second surface facing the skin side of the wearer; the absorbent article includes a waist / hip portion corresponding to the waist / hips of the wearer, and a multilayer nonwoven fabric is positioned in the waist / hip portion; and the constituent fibers of the first layer on the second surface side have a smaller fiber diameter than the constituent fibers on the first surface side of the first layer. 3. Absorbent article according to claim 1 or 2, in which in the area of overlapping of the interlayer bonded part in the direction of the thickness of the multilayer nonwoven material, the first layer has a region where the molten resin component of the second layer has entered and a region where the molten resin component has not entered ... 4. An absorbent article according to claim 1 or 2, wherein: the second layer includes, in some portions, in a plan view of the multilayer nonwoven fabric, fused bonded portions in which the fusion-bonded fibers are bonded together; and the fused bonded portions form a second layer portion in the corresponding interlayer bonded portion. 5. An absorbent article according to claim 1 or 2, wherein: the absorbent article includes an elasticized area in the waist / hip portion; and multilayer nonwoven fabric is located in the elasticized area. 6. An absorbent article according to claim 1 or 2, wherein: an absorbent article includes a liquid-retaining absorbent member; and the multilayer nonwoven fabric is located closer to the skin of the wearer than the absorbent body. 7. An absorbent article according to claim 1 or 2, wherein: an absorbent article includes an absorbent assembly including a liquid-retaining absorbent member and an outer cover attached to the non-skin side of the surface of the absorbent assembly; the outer cover includes a front outer cover to be placed on the front side of the wearer and a rear outer cover to be placed on the rear side; at least the rear outer cover includes a multilayer nonwoven fabric; and the multilayer nonwoven fabric is positioned with the second surface facing the skin side of the wearer. 8. An absorbent article according to claim 1 or 2, wherein the first layer of the multilayer nonwoven fabric has a basis weight of 8 to 40 g / m ² . 9. An absorbent article according to claim 1 or 2, wherein the second layer of the multilayer nonwoven fabric has a basis weight of 3 to 25 g / m ² . 10. An absorbent article according to claim 1 or 2, wherein: the total area of the interlayer bonded portions of the multilayer nonwoven fabric is 15% or less of the total area of the multilayer nonwoven fabric; and the area of one interlayer bonded portion is 1 mm ² or less. 11. An absorbent article according to claim 1 or 2, wherein: the first layer of the multilayer nonwoven fabric is mainly formed by fibers that are not amenable to fusion bonding; and fibers that are not amenable to fusion bonding constitute at least 50% of the constituent fibers of the first layer. 12. An absorbent article according to claim 1 or 2, wherein the non-fusion-bonding fibers are short fibers. 13. An absorbent article according to claim 1 or 2, wherein the constituent fibers of the first layer have a shorter interfiber spacing than the second layer. 14. An absorbent article according to claim 1 or 2, wherein the constituent fibers of the first layer of the multilayer nonwoven fabric have a smaller fiber diameter than the constituent fibers of the second layer. 15. An absorbent article according to claim 1 or 2, wherein the constituent fibers of the first layer of the multilayer nonwoven fabric on the second surface side have a shorter interfiber distance than the constituent fibers of the first layer on the first surface side. 16. An absorbent article according to claim 1 or 2, wherein the elastic member is sandwiched between a plurality of fibrous layers of the multilayer nonwoven fabric. 17. An absorbent article according to claim 1 or 2, wherein one or both of the first layer and the second layer of the nonwoven laminate is / is stretchable in a width direction orthogonal to the longitudinal direction of the absorbent article.

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