JP7410665B2 - Nonwoven fabric for absorbent articles and its manufacturing method - Google Patents

Description

The present invention relates to a nonwoven fabric for absorbent articles, and more particularly to a nonwoven fabric for absorbent articles that can be used as a top sheet and a diffusion layer of an absorbent article.

Absorbent articles (eg, diapers, incontinence pads, napkins, panty liners, etc.) are composed of a top sheet, a diffusion layer, an absorbent body, and the like. The top sheet is required to quickly draw moisture that comes into contact with the absorbent article into the absorbent article, provide a good tactile sensation to human skin, and prevent the drawn moisture from returning to the top sheet surface. be done. The diffusion layer is required to quickly pass the moisture drawn in by the top sheet while diffusing it, and move it to the absorbent body. Absorbers are required to firmly retain absorbed moisture.

For example, Patent Document 1 discloses a topsheet for an absorbent article that includes a first fiber layer that comes into contact with the skin and a second fiber layer that is adjacent to the first fiber layer, wherein the first fiber layer is , a fiber layer containing 50% by mass or more of a first core-sheath composite staple fiber whose core component contains polypropylene and whose sheath component contains a thermoplastic resin having a melting point lower than the melting point of the polypropylene by 5° C. or more; In the second fiber layer, the core component includes a polyester resin, the sheath component includes a thermoplastic resin having a melting point lower than the melting point of the polyester resin by 50° C. or more, and the center of gravity of the core component is shifted from the center of gravity of the fiber. The fiber layer contains 50% by mass or more of second core-sheath type composite short fibers, and the first core-sheath type composite short fibers have a fineness of 0.5 dtex or more and 2.1 dtex or less, and The composite short fibers have a fineness of 2.2 dtex or more and 5.2 dtex or less, and at least a portion of the first core-sheath type composite short fibers and the second core-sheath type composite short fibers are the first core-sheath type composite short fibers. Disclosed is a nonwoven fabric that can be used as a top sheet for absorbent articles, the short fibers being thermally bonded to the sheath component of the second core-sheath composite short fibers. Patent Document 1 discloses that the nonwoven fabric has an advantageous effect of having a smooth touch and good liquid absorption properties such as run-off and liquid absorption rate.

For example, Patent Document 2 discloses fibers containing cellulose fibers that have intrafiber crosslinks, are deformed, and are fixed by adding a crosslinking agent to cellulose fibers and subjecting them to mechanical stirring, fluffing, and heat treatment. A sheet that can be used as a diffusion layer for absorbent articles is disclosed. Patent Document 2 discloses that the sheet quickly absorbs liquids such as urine and body fluids on the top sheet even under pressurized compression, and quickly diffuses the liquid to the absorbent body without retaining much of the absorbed liquid. It is disclosed that it has the advantageous effect of being able to be released.

JP2015-204983A Japanese Patent Application Publication No. 08-308873

Conventionally, in order to manufacture absorbent articles, it has been necessary to bond together a top sheet nonwoven fabric and a diffusion layer nonwoven fabric that have been manufactured separately. In particular, when the nonwoven fabric for the top sheet or the nonwoven fabric for the diffusion layer contains cellulose fibers, a method is adopted in which adhesive is used when bonding the nonwoven fabric for the top sheet and the nonwoven fabric for the diffusion layer. In some cases, stable liquid absorption performance could not be exhibited due to the formation of gaps between the adhesive and the nonwoven fabric and the unstable amount of adhesive. Furthermore, in recent years, absorbent articles have been required to have properties that make the color of attached liquid less noticeable (also referred to as "masking properties").

On the other hand, there is a continuing demand for cost reduction in absorbent articles, and since the use of adhesives leads to increased costs, it was necessary to consider a method of bonding without using adhesives.

As a result of extensive studies, the present inventors have found that if it is possible to manufacture a nonwoven fabric that has the properties of both a nonwoven fabric for a top sheet and a nonwoven fabric for a diffusion layer in one manufacturing process, it will simplify the production of absorbent articles. It has been found that stable liquid absorption performance can be achieved. Furthermore, it was discovered that such a nonwoven fabric is suitable for use in absorbent articles, leading to the completion of the present invention.

The present disclosure, in one aspect, provides a nonwoven fabric for absorbent articles, which includes:
A nonwoven fabric comprising a first fiber layer and a second fiber layer located on one main surface of the first fiber layer,
the first fiber layer includes adhesive fibers,
The first fibrous layer contains 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fibrous layer,
the second fiber layer includes cellulose fibers,
The second fibrous layer contains 60% by mass or more and 100% by mass or less of the cellulose fibers based on the total mass of the second fibrous layer,
In the first fiber layer, fibers are bonded to each other by the adhesive fibers,
The first fiber layer and the second fiber layer are integrated by intertwining the fibers,
the first fibrous layer is located closer to the user's skin;
Satisfying either (i) or (ii) below,
(i) The thickness change rate of the nonwoven fabric measured by the following measuring method is 16% or more. (ii) The fibers included in the second fiber layer are not bonded by the adhesive fibers. For absorbent articles It is a non-woven fabric.
[Thickness change rate]
Using a thickness measuring machine, the thickness of the nonwoven fabric was measured with a load of 294Pa or 1.96kPa applied to the nonwoven fabric, and the thickness at a load of 294Pa (P1) and the thickness at a load of 1.96kPa (P2) were measured. Calculated based on the following formula.
Thickness change rate (%) = [(P1-P2)/P1] x 100

Furthermore, the present disclosure provides, as another aspect, a method for manufacturing a nonwoven fabric for absorbent articles, which includes:
An absorbent article that is a nonwoven fabric including a first fiber layer and a second fiber layer located on one main surface of the first fiber layer, the first fiber layer being located closer to the user's skin. A method for producing a nonwoven fabric for use,
Producing a first fibrous web containing 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the web;
an adhesion step of adhering the fibers of the first fibrous web to each other using the adhesive fibers;
producing a second fibrous web containing cellulose fibers in an amount of 60% by mass or more and 100% by mass or less based on the total mass of the web;
a laminating step of laminating the first fibrous web and the second fibrous web to obtain a laminated fibrous web;
An intertwining step of intertwining and integrating the fibers of the first fiber web and the second fiber web with respect to the laminated fiber web,
The first fibrous layer includes the first fibrous web, and the second fibrous layer includes the second fibrous web.

The nonwoven fabric for absorbent articles according to the embodiment of the present invention can be used as a nonwoven fabric that has both the properties of a top sheet and a diffusion layer. Therefore, the nonwoven fabric for absorbent articles of the present invention can be suitably used to manufacture absorbent articles, and the manufacturing method thereof can be simplified.

FIG. 1 is a photograph of the surface of the five nonwoven fabric samples of Example 7, after the second measurement of liquid absorption time, where the area with the same depth of color as artificial menstrual blood was the smallest. In the nonwoven fabric of Example 7, there was substantially no portion with a color as deep as that of artificial menstrual blood. FIG. 2 is a photograph of the surface of the nonwoven fabric sample of the five nonwoven fabric samples of Comparative Example 3, after the second measurement of liquid absorption time, the area with the same color density as artificial menstrual blood is the smallest. In the nonwoven fabric of Comparative Example 3, a portion with a color similar to that of artificial menstrual blood clearly existed after the first liquid absorption time measurement.

In one aspect, the present disclosure provides a new nonwoven fabric for absorbent articles.
The nonwoven fabric of the embodiment of the present invention is
A nonwoven fabric comprising a first fiber layer and a second fiber layer located on one main surface of the first fiber layer,
the first fiber layer includes adhesive fibers,
The first fibrous layer contains 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fibrous layer,
the second fiber layer includes cellulose fibers,
The second fibrous layer contains 60% by mass or more and 100% by mass or less of the cellulose fibers based on the total mass of the second fibrous layer,
In the first fiber layer, fibers are bonded to each other by the adhesive fibers,
The first fiber layer and the second fiber layer are integrated by intertwining the fibers,
the first fibrous layer is located closer to the user's skin;
Satisfying either (i) or (ii) below,
(i) The thickness change rate of the nonwoven fabric measured by the following measuring method is 16% or more. (ii) The fibers included in the second fiber layer are not bonded by the adhesive fibers. For absorbent articles It is a non-woven fabric.
[Thickness change rate]
Using a thickness measuring machine, the thickness of the nonwoven fabric was measured with a load of 294Pa or 1.96kPa applied to the nonwoven fabric, and the thickness at a load of 294Pa (P1) and the thickness at a load of 1.96kPa (P2) were measured. Calculated based on the following formula.
Thickness change rate (%) = [(P1-P2)/P1] x 100

The nonwoven fabric for absorbent articles according to the embodiment of the present invention is preferably used for applications that directly contact human skin (for example, top sheets for absorbent articles, such as diapers, incontinence pads, napkins, panty liners, etc.). can also be used for applications having the function of a diffusion layer).

A nonwoven fabric according to an embodiment of the present invention is a nonwoven fabric including a first fibrous layer and a second fibrous layer located on one main surface of the first fibrous layer, wherein the first fibrous layer is made of adhesive fibers. The first fibrous layer includes 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fibrous layer, and the first fibrous layer includes the adhesive fibers that bind the fibers to each other. is glued.

(Adhesive fiber)
In the nonwoven fabric of the embodiment of the present invention, "adhesive fibers" exhibit adhesive properties by adhesion treatment (e.g., thermal adhesion treatment, electron beam irradiation, ultrasonic welding (ultrasonic welder), etc.) and bond fibers to each other. It refers to fibers that can be bonded together to form bonding locations, and is not particularly limited as long as the nonwoven fabric targeted by the present disclosure can be obtained.

The adhesive fibers include, for example, synthetic fibers made of thermoplastic resin.
The thermoplastic resin is not particularly limited as long as the nonwoven fabric targeted by the present disclosure can be obtained, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate, and copolymers thereof. Polyester resins such as polymers; polypropylene, polyethylene (including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, propylene copolymer whose main component is propylene (propylene-ethylene copolymer) Polyolefin resins such as polymers, propylene-butene-1-ethylene copolymers), ethylene-acrylic acid copolymers, and ethylene-vinyl acetate copolymers; polyamides such as nylon 6, nylon 12, and nylon 66 Resin; Acrylic resin; Engineering plastics such as polycarbonate, polyacetal, polystyrene, and cyclic polyolefin, and their elastomers can be exemplified, and any material can be selected from these.

The synthetic fiber may be a single fiber made of one or more thermoplastic resins selected from the above, or may be a composite fiber made of two or more components (also referred to as "sections"). In the composite fiber, each component may be made of one thermoplastic resin, or may be a mixture of two or more thermoplastic resins. The composite fiber may be, for example, a core-sheath type composite fiber, a split type composite fiber, a sea-island type composite fiber, or a side-by-side type composite fiber. The core-sheath type composite fiber may be an eccentric core-sheath type composite fiber in which the center of the core component and the center of the sheath component do not coincide in the fiber cross section, and may be an eccentric core-sheath type composite fiber in which the center of the core component and the center of the sheath component coincide in the fiber cross section. It may be a sheath type composite fiber. The adhesive fiber preferably includes a core-sheath type conjugate fiber, and more preferably includes an eccentric core-sheath type conjugate fiber.

Synthetic fibers, whether monofilament or composite fibers, may have irregular cross-sections. In the case of a core-sheath type conjugate fiber and a sea-island type conjugate fiber, the core component and/or the island component may have an irregular cross section in the fiber cross section.
When the synthetic fiber has an irregular cross section, the cross section may be an ellipse, a polygon, a star, or a shape in which a plurality of convex portions are joined at the base (for example, a clover shape).
In this embodiment, two or more synthetic fibers may be used in combination as the synthetic fibers.

When the synthetic fiber is a composite fiber, two or more components may be arranged so that a thermoplastic resin with a lower melting point forms part of the fiber surface. A thermoplastic resin with a low melting point (low melting point component) melts or softens when heat is applied in the process of producing a nonwoven fabric, and becomes an adhesive component. The low melting point component can contribute to adhesion of fibers to each other or to other members, and can form bonding points.
When the synthetic fiber is a composite fiber, it is preferable that the low melting point component is exposed in the cross section of the fiber over a length of 50% or more of the length of the peripheral surface of the fiber, and a length of 60% or more of the length of the peripheral surface of the fiber. It is more preferable that the length of the fiber is exposed, more preferably that 80% or more of the length is exposed, and it is particularly preferable that the entire circumferential surface of the fiber is exposed.

In an embodiment of the present invention, the fibers of the first fiber layer are bonded to each other by adhesive fibers.
Since the low melting point component of the adhesive fiber is not exposed to too small a portion on the fiber peripheral surface in the fiber cross section, there is a more appropriate area where bonding is possible, and the number of bonding points between the fibers is more appropriate. The adhesion strength at the adhesion points between fibers becomes more appropriate, and adhesion by the adhesive fibers can be made more sufficient. Therefore, the prevention of fuzz of the nonwoven fabric and the strength of the nonwoven fabric can be made more suitable. Furthermore, in the subsequent entanglement, the degree to which the adhesion between the fibers is resolved becomes more appropriate, and the fluffing of the nonwoven fabric can be suppressed and the strength of the nonwoven fabric can be made more sufficient.
As will be described later, in the nonwoven fabric of the embodiment of the present invention, the second fiber layer includes cellulose fibers, and the first fiber layer and the second fiber layer are integrated by intertwining.

Combinations of thermoplastic resins constituting composite fibers include, for example, combinations of polyolefin resins and polyester resins such as polyethylene/polyethylene terephthalate, polypropylene/polyethylene terephthalate, and propylene copolymer/polyethylene terephthalate (polyolefin resin/polyester resin). combinations of two types of polyolefin resins such as polyethylene/polypropylene, propylene copolymer/polypropylene, ethylene-acrylic acid copolymer/polypropylene (polyolefin resin/polyolefin resin), and for example, polybutylene saccharide. Contains a combination of two types of polyester resins with different melting points (polyester resin/polyester resin) such as ester/polylactic acid.

Note that the thermoplastic resin illustrated as a component of the single fiber or composite fiber may contain other components as long as it contains 50% by mass or more of the specifically indicated thermoplastic resin. For example, in the combination of polyethylene/polyethylene terephthalate, "polyethylene" may contain other thermoplastic resins, additives, etc. as long as it contains 50% by mass or more of polyethylene. This also applies to the following examples.

When the adhesive fiber is a core-sheath composite fiber in which the sheath is made of a thermoplastic resin with a lower melting point, the core/sheath combination may be, for example, polyethylene terephthalate/polyethylene, polyethylene terephthalate/polypropylene, polyethylene terephthalate/propylene. Copolymers, polytrimethylene terephthalate/polyethylene, polybutylene terephthalate/polyethylene, polyethylene terephthalate/copolyester (e.g., polyethylene terephthalate copolymerized with isophthalic acid), polylactic acid/polybutylene succinate, polypropylene/ethylene-acrylic acid Contains copolymers. A core-sheath composite fiber whose sheath is made of polyethylene (e.g., high-density polyethylene, low-density polyethylene, or linear low-density polyethylene) or copolymer polyester is heat-treated at a temperature higher than the melting point of the thermoplastic resin constituting the sheath. By doing so, the sheath melts or softens, and has the property of adhering the fibers to each other to form a bonding point.

When the adhesive fiber includes a core-sheath type composite fiber, the core-sheath composite ratio (volume ratio, core/sheath) of the core-sheath type composite fiber may be, for example, 80/20 to 20/80, particularly It may be 60/40 to 40/60.
If the proportion of the sheath is not too small, the adhesion between the fibers will be more sufficient, and the suppression of fuzz may be more suitable, or the strength of the nonwoven fabric may be more suitable. Alternatively, the strength of a nonwoven fabric may be more suitable. When the proportion of the sheath is not too large, the proportion of the core component that maintains the fiber shape becomes more sufficient, and the strength of the nonwoven fabric can be made more suitable.

The adhesive fiber includes two or more fibers, and the adhesive components of the fibers may have different melting points. For example, the adhesive fiber may include two fibers, and the difference in melting point of the adhesive components of these fibers may be 10°C or more and 40°C or less, and further may be 15°C or more and 30°C or less.

The fineness of the adhesive fiber is preferably 1.0 dtex or more and 5.0 dtex or less, more preferably 1.2 dtex or more and 4.8 dtex or less, and even more preferably 1.3 dtex or more and 4.5 dtex or less. Preferably, it is particularly preferably 1.5 dtex or more and 3.5 dtex or less.
When the fineness of the adhesive fiber is within the above range, the strength of the nonwoven fabric is further improved and the texture of the nonwoven fabric is softer, which is preferable. Further, it is preferable that the fineness of the adhesive fiber is within the above-mentioned range, since the liquid absorption time can be shortened and the wetback prevention property can be improved.
When the adhesive fibers include splittable conjugate fibers, they may include adhesive fibers having a fineness of 0.1 dtex or more and less than 1.0 dtex.

The fiber diameter of the adhesive fiber is preferably 10 μm or more and 33 μm or less, more preferably 12 μm or more and 30 μm or less, even more preferably 14 μm or more and 25 μm or less, and particularly preferably 16 μm or more and 22 μm or less. preferable.
When the fiber diameter of the adhesive fiber is within the above range, the strength of the nonwoven fabric is further improved and the texture is softer than that of a nonwoven fabric, which is preferable. Further, it is preferable that the fiber diameter of the adhesive fiber is within the above-mentioned range, since the liquid absorption time can be shortened and the wetback prevention property can be improved.
When the adhesive fibers include splittable conjugate fibers, they may include adhesive fibers having a fiber diameter of 3 μm or more and less than 10 μm.

The fiber length of the adhesive fiber is preferably 25 mm or more and 100 mm or less, more preferably 30 mm or more and 70 mm or less, and even more preferably 35 mm or more and 60 mm or less.
It is preferable that the fiber length of the adhesive fiber is within the above-mentioned range because the intertwining properties of the fibers become more suitable. In particular, the nonwoven fabric of the present disclosure can be manufactured by once adhering constituent fibers to each other using adhesive fibers and then performing an interlacing treatment. Therefore, since the fiber length is not too long, the number of adhesion points in one fiber becomes more appropriate, and the entanglement with the constituent fibers of the second fiber layer can be made more suitable. Furthermore, since the fiber length is not too short, the number of adhesion points in one fiber becomes more appropriate, and the intertwining properties of the fibers can be made more suitable to the extent that the texture of the nonwoven fabric can be made more sufficiently soft.

Preferably, the adhesive fiber has three-dimensional crimp. The term "three-dimensional crimp" is used herein to distinguish from mechanical crimp, where the crests (or crests) of the crimp are at acute angles. Three-dimensional crimp includes, for example, crimp with curved peaks (wave-shaped crimp), crimp with spirally curved peaks (spiral crimp), and a mixture of wave-shaped crimp and spiral crimp. This refers to crimps that are a mixture of sharp crimps, mechanical crimps, and at least one of wave-shaped crimps and spiral crimps. The adhesive fibers may have mechanical crimps.
When the adhesive fiber is a conjugate fiber, it may be an overtly crimpable conjugate fiber. "Expected crimp composite fiber" refers to a fiber that exhibits three-dimensional crimp at the fiber stage. The actual crimpable composite fiber is different from the latent crimpable composite fiber, which develops three-dimensional crimp through heat treatment accompanied by fiber contraction.

When the adhesive fiber is an eccentric core-sheath type composite fiber, the eccentricity is preferably 5% or more and 50% or less, more preferably 7% or more and 30% or less. The eccentricity here is defined by the following equation.
(Formula) Eccentricity (%) = (distance between the center of the single fiber and the center of the core component) x 100/(radius of the single fiber)
When the adhesive fiber has three-dimensional crimp, the bulk of the first fiber layer becomes high, and it is possible to suppress the liquid from coming out to the surface of the first fiber layer due to liquid return, and also to improve masking properties. It is preferable because it can be done. Further, it is preferable that the adhesive fiber has three-dimensional crimp, since the first fiber layer has cushioning properties and can improve the feeling of wearing. Adhesive fibers can be used alone or in combination.

The adhesive fibers preferably have lower hydrophilicity than the cellulose fibers included in the second fiber layer. The hydrophilicity of fibers can be determined, for example, by the contact angle. Here, the contact angle refers to the angle between the water surface and the fiber surface (taking the angle inside the water) at the location where the free surface of the water contacts the fiber. Since the adhesive fibers have lower hydrophilicity than the cellulose fibers contained in the second fiber layer, it is possible to suppress the liquid from coming out to the surface of the first fiber layer due to liquid return. This is preferred because it facilitates drawing liquid from the layer into the second fibrous layer.

The adhesive fiber may be a fiber containing a hydrophilic fiber treatment agent. The form in which the hydrophilic fiber treatment agent is contained is not particularly limited. The hydrophilic fiber treatment agent may be attached to the surface of the adhesive fiber or may be dispersed within the fiber. The hydrophilic fiber treatment agent can be attached to the surface of the adhesive fiber by spraying onto the surface of the adhesive fiber, or by applying it to the surface of the adhesive fiber by any method. By melt-spinning a thermoplastic resin into which a hydrophilic fiber treatment agent has been kneaded, the hydrophilic fiber treatment agent can be dispersed in the fibers. The type of hydrophilic fiber treatment agent is not particularly limited. The hydrophilic fiber treatment agent may be a known one. Examples of the hydrophilic fiber treatment agent include a fiber treatment agent containing a surfactant. As the surfactant, anionic, cationic, amphoteric, nonionic surfactants, etc. can be used.

The content of the hydrophilic fiber treatment agent may be 0.1% by mass or more and 2.0% by mass or less, when the fiber mass (the mass of the fiber excluding the fiber treatment agent) is 100% by mass. The content of the hydrophilic fiber treatment agent may particularly be 0.15% by mass or more and 1.0% by mass or less, and more particularly 0.2% by mass or more and 0.6% by mass or less.

The first fiber layer preferably contains 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fiber layer, and preferably contains 70% by mass or more and 100% by mass or less of the adhesive fibers. It is more preferable that the adhesive fiber is contained in an amount of 80% by mass or more and 100% by mass or less, and it is even more preferable that the adhesive fiber is contained in a range of 90% by mass or more and 100% by mass or less. The first fiber layer contains 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fiber layer, thereby suppressing fuzz on the surface of the nonwoven fabric and stabilizing the shape of the nonwoven fabric. This is preferable because it can improve the properties.

The first fiber layer may contain fibers other than adhesive fibers. Fibers other than adhesive fibers include, for example, cellulose fibers, natural fibers that are not cellulose fibers (e.g., wool, silk, etc.), synthetic fibers that are not adhesive fibers (e.g., when melting the adhesive component of adhesive fibers, or synthetic fibers that do not soften or exhibit adhesive properties), and are not particularly limited as long as the nonwoven fabric targeted by the present invention can be obtained.

Fibers other than adhesive fibers may be included in a proportion of 40% by mass or less, particularly 30% by mass or less, more particularly 20% by mass or less, and even more. In particular, it may be contained in a proportion of 10% by mass or less, and is not particularly limited as long as the nonwoven fabric targeted by the present invention can be obtained. In an embodiment of the present invention, the first fiber layer may be a nonwoven fabric made of adhesive fibers and cellulose fibers, or may be a nonwoven fabric made of adhesive fibers.

In an embodiment of the invention, the fibers of the first fiber layer are bonded together by adhesive fibers. That is, the first fibrous layer of the embodiment of the present invention includes a bonding location. This ensures both the strength of the nonwoven fabric and the suppression of fluff, and improves the ease of handling. Adhesion by adhesive fibers can be achieved by a portion of the adhesive fibers melting, softening, or changing to exhibit adhesive properties and fixing fibers that intersect with or contact with the adhesive fibers. Specifically, the adhesion between fibers refers to the adhesion between adhesive fibers, and when other fibers are included, it also refers to the adhesion between adhesive fibers and other fibers. Say something. The adhesion may be by thermal adhesion in which heat is applied to melt or soften some of the adhesive fibers, or by irradiation with electron beams or the like or ultrasonic welding.

The first fiber layer preferably has a basis weight of 10 g/m ² or more and 50 g/m ² or less, more preferably 15 g/m ² or more and 45 g/m ² or less, and 20 g/m ² or more and 40 g/m 2 or less. It is even more preferable to have a basis weight of m ² or less, and particularly preferably to have a basis weight of 20 g/m ² or more and 35 g/m ² or less. When the first fiber layer has a basis weight within the above-mentioned range, the bulk of the first fiber layer becomes high, which prevents liquid from coming out to the surface of the first fiber layer due to liquid return, and also improves masking properties. This is preferable because it can be done.

In an embodiment of the present invention, the second fibrous layer includes cellulose fibers,
The second fibrous layer contains 60% by mass or more and 100% by mass or less of the cellulose fibers based on the total mass of the second fibrous layer, and the first fibrous layer and the second fibrous layer contain intertwining of fibers. It is integrated by

Furthermore, in an embodiment of the present invention, the first fibrous layer is located closer to the user's skin;
Satisfies either (i) or (ii) below.
(i) The thickness change rate of the nonwoven fabric measured by the following measuring method is 16% or more. (ii) The fibers included in the second fiber layer are not bonded by the adhesive fibers [Thickness change rate ]
Using a thickness measuring machine, the thickness of the nonwoven fabric was measured with a load of 294Pa or 1.96kPa applied to the nonwoven fabric, and the thickness at a load of 294Pa (P1) and the thickness at a load of 1.96kPa (P2) were measured. Calculated based on the following formula.
Thickness change rate (%) = [(P1-P2)/P1] x 100

(cellulose fiber)
In the nonwoven fabric of the embodiment of the present invention, "cellulose fiber" is also called cellulose fiber, and generally refers to fiber made from cellulose.
Cellulosic fibers are natural fibers derived from plants such as cotton, hemp, linen, ramie, jute, banana, bamboo, kenaf, shellfish, hemp, and kapok; obtained by the viscose method. Regenerated fibers such as rayon (viscose rayon) and polynosic rayon, cupro obtained by the copper ammonia method, and Tencel (registered trademark) and Lyocell (registered trademark) obtained by the solvent spinning method; cellulose fibers obtained by the melt spinning method; and semi-synthetic fibers such as acetate fibers, and is not particularly limited as long as the nonwoven fabric targeted by the present invention can be obtained.

The fineness of the cellulose fiber is preferably 1.0 dtex or more and 5.0 dtex or less, more preferably 1.0 dtex or more and 4.0 dtex or less, and even more preferably 1.0 dtex or more and 3.5 dtex or less. preferable.
When the fineness of the cellulose fiber is within the above range, the fineness is not too small because it forms voids in the second fiber layer, making it easier to draw liquid from the first fiber layer, and the fineness is not too large. This is preferable because the formation of the second fiber layer becomes good and the surface of the second fiber layer can be flattened and brought into uniform contact with the absorbent body. In addition, when the fineness of the cellulose fiber is within the above range, the entangling property of the fibers becomes more suitable, and the entangling property of the nonwoven fabric is not too low, so that the strength of the nonwoven fabric and the strength of the first fiber layer and the second fiber layer are improved. This is preferable because the integration becomes more suitable, and the interlacing property of the nonwoven fabric is not too high, which makes the voids in the second fiber layer more suitable.

The fiber diameter of the cellulose fiber is preferably 5 μm or more and 25 μm or less, more preferably 8 μm or more and 20 μm or less, and even more preferably 10 μm or more and 17 μm or less.
When the fiber diameter of the cellulosic fiber is within the above range, the fiber diameter is not too small to form voids in the second fiber layer, making it easier to draw liquid from the first fiber layer, and also because the fiber diameter is not too small. It is preferable that the size is not too large because the formation of the second fiber layer becomes good and the surface of the second fiber layer can be flattened and brought into uniform contact with the absorbent body. In addition, when the fiber diameter of the cellulose fiber is within the above range, the entangling property of the fibers is more suitable, and the entangling property of the nonwoven fabric is not too low, so that the strength of the nonwoven fabric and the first fiber layer and the second fiber layer are This is preferable because the integration of the nonwoven fabric is more suitable, and the interlacing property of the nonwoven fabric is not too high, which makes the voids in the second fiber layer more suitable.

The fiber length of the cellulose fiber is preferably 25 mm or more and 100 mm or less, more preferably 30 mm or more and 70 mm or less, and even more preferably 35 mm or more and 60 mm or less.
It is preferable that the fiber length of the cellulose fibers is within the above-mentioned range because the intertwining properties of the fibers are suitable. It is preferable that the fiber length is not too large because the strength of the nonwoven fabric becomes more suitable. Furthermore, it is preferable that the fiber length is not too small because the voids in the second fiber layer become more suitable and the integration of the first fiber layer and the second fiber layer becomes more suitable.

The fiber cross section (cross section or cross section perpendicular to the length direction of the fibers) of the cellulose fibers may be circular or non-circular, and examples of non-circular shapes include ellipsoids and Y-shapes. , X-shaped, I-shaped, multilobed, polygonal, star-shaped, chrysanthemum-shaped, etc. It is preferable that the cross section of the fibers is non-circular, since voids are formed in the second fiber layer and liquid is easily drawn in from the first fiber layer.

In addition, it is preferable that the cross section of the cellulose fiber includes a multilobal cellulose fiber, and when the cross section of the fiber includes a multilobal cellulose fiber, voids are formed in the second fiber layer. , this has the advantageous effect of making it easier to draw in liquid from the first fiber layer. It is more preferable to include cellulose fibers having a multilobal fiber cross section of three or more lobes. When cellulosic fibers having a multilobal fiber cross section of three or more lobes are included, voids are formed in the second fibrous layer, which has the advantageous effect of making it easier to draw in liquid from the first fibrous layer.

The cellulose-based fibers are preferably chemical fibers such as regenerated fibers and semi-synthetic fibers. Compared to natural fibers, chemical fibers can further reduce variations in fineness, fiber diameter, and fiber length, and can make the size of the voids in the second fiber layer relatively uniform, making it easier to absorb liquid. It is more preferable because the second fiber layer makes it difficult to hold.
Cellulosic fibers can be used alone or in combination.

The second fibrous layer preferably contains 60% by mass or more and 100% by mass or less of the cellulose fibers based on the total mass of the second fibrous layer, and preferably contains 70% by mass or more and 100% by mass or less of the cellulose fibers. It is more preferable that the cellulose-based fibers are contained in an amount of 80% by mass or more and 100% by mass or less, and it is still more preferable that the cellulose-based fibers are contained in a range of 90% by mass or more and 100% by mass or less. When the second fiber layer contains 60% by mass or more and 100% by mass or less of the cellulose fiber based on the total mass of the second fiber layer, it is easy to draw liquid from the first fiber layer to the second fiber layer, and the second fiber layer This is preferable because the liquid can be easily diffused.

The second fiber layer may contain fibers other than cellulose fibers. Fibers other than cellulose fibers include, for example, natural fibers that are not cellulose fibers (e.g., wool, silk, etc.), adhesive fibers, and synthetic fibers that are not adhesive fibers (for example, when the adhesive components of adhesive fibers are melted, or synthetic fibers that do not soften or exhibit adhesive properties), and are not particularly limited as long as the nonwoven fabric targeted by the present invention can be obtained.

Fibers other than cellulose fibers may be included in a proportion of 40% by mass or less, particularly 30% by mass or less, more particularly 20% by mass or less, and even more. In particular, it may be contained in a proportion of 10% by mass or less, and is not particularly limited as long as the nonwoven fabric targeted by the present invention can be obtained. In an embodiment of the present invention, the second fiber layer may be a nonwoven fabric made of adhesive fibers and cellulose fibers, or may be a nonwoven fabric made of cellulose fibers. When the second fiber layer includes adhesive fibers, it is preferable that the melting point of the adhesive component of the adhesive fibers contained in the second fiber layer is lower than the melting point of the adhesive component of the adhesive fibers contained in the first fiber layer. In particular, when the second fiber layer contains adhesive fibers, the adhesive component of the adhesive fibers contained in the first fiber layer is an adhesive that does not melt at the temperature at which the adhesive component of the adhesive fibers contained in the second fiber layer melts. Preferably, it is a component.

In an embodiment of the invention, the fibers of the second fiber layer are intertwined. That is, the nonwoven fabric of the embodiment of the present invention includes intertwined portions. Thereby, the strength of the nonwoven fabric can be improved, and the thickness of the second fiber layer can be made uniform so that it can be brought into uniform contact with the absorbent body. Fiber-to-fiber entanglement can be achieved by subjecting the nonwoven fabric to a flow of material to entangle the fibers. Specifically, the intertwining of fibers refers to the intertwining of cellulose fibers with other cellulose fibers, and when other fibers are further included, in addition, the intertwining of cellulose fibers with other fibers (for example, adhesive properties) fibers). The entanglement may be performed by a needle punch method or by a fluid stream, and the fluid stream may be a water stream, an air stream, a water vapor stream, or the like. In embodiments of the present invention, a stream of water or steam is preferably used to entangle the cellulosic fibers.

The second fiber layer preferably has a basis weight of 10 g/m ² or more and 50 g/m ² or less, more preferably 15 g/m ² or more and 45 g/m ² or less, and 20 g/m ² or more and 40 g/m 2 or less. It is even more preferable to have a basis weight of m ² or less, and particularly preferably to have a basis weight of 20 g/m ² or more and 35 g/m ² or less. When the second fiber layer has a basis weight within the above range, it is preferable because the second fiber layer does not hold too much liquid and the liquid can be transferred to the absorbent body while being diffused.

The nonwoven fabric of the embodiment of the present invention has a laminated structure in which a first fiber layer and a second fiber layer are laminated, and the first fiber layer and the second fiber layer are composed of fibers of the first fiber layer and fibers of the second fiber layer. It is integrated by intertwining the fibers of the two fiber layers. Fiber entanglement can be accomplished by subjecting the nonwoven fabric to a flow of material to entangle the fibers. Specifically, the intertwining of fibers refers to the intertwining of cellulose fibers and adhesive fibers, and when other fibers are further included, the intertwining of cellulose fibers and other fibers, and the intertwining of adhesive fibers. Refers to the entanglement of fibers with other fibers. The entanglement may be performed by a needle punch method or by a fluid stream, and the fluid stream may be a water stream, an air stream, a water vapor stream, or the like. In embodiments of the present invention, a stream of water or steam is preferably used to entangle the cellulosic fibers.

In the nonwoven fabric of the embodiment of the present invention, (ii) it is preferable that the fibers contained in the second fiber layer are not bonded by the adhesive fibers contained in the first fiber layer. Since the fibers contained in the second fiber layer are not bonded by the adhesive fibers contained in the first fiber layer, the wettability of the surface of the nonwoven fabric becomes good and masking properties are good, which is preferable. The fact that the fibers included in the second fiber layer are not bonded by the adhesive fibers included in the first fiber layer means that if the adhesive fibers exhibit adhesive properties due to melting of an adhesive component, the fibers included in the second fiber layer are Since it deforms due to melting, it can be confirmed by the presence or absence of deformation. A nonwoven fabric in which the fibers contained in the second fiber layer are bonded by the adhesive fibers contained in the first fiber layer is produced, for example, after the fibers in the first fiber layer and the fibers in the second fiber layer are integrated by intertwining. It can be obtained by bonding fibers together using adhesive fibers, but in that case, the volume of the first fiber layer may not be sufficient or the texture of the first fiber layer may become hard.

In the nonwoven fabric of the embodiment of the present invention, when the second fiber layer includes adhesive fibers, the fibers included in the first fiber layer may be bonded by the adhesive fibers included in the second fiber layer. In particular, when the melting point of the adhesive component of the adhesive fibers contained in the second fiber layer is lower than the melting point of the adhesive component of the adhesive fibers contained in the first fiber layer, the first fiber layer and the second fiber layer are integrated. This is preferable because the bulk of the first fiber layer can be maintained well while the texture of the first fiber layer can be maintained well.

Preferably, in the nonwoven fabric of the embodiment of the present invention, no openings are formed in the first fiber layer and the second fiber layer. Masking properties may not be good due to the openings formed in the first fiber layer and the second fiber layer.

The nonwoven fabric of the embodiment of the present invention preferably has a basis weight of 30 g/m ² or more and 100 g/m ² or less, more preferably 30 g/m ² or more and 80 g/m ² or less, and 30 g/m ² It is even more preferable to have a basis weight of 30 g/m ² or more and 65 g/m 2 or less, and particularly preferably 30 g/m ² or more and 65 g/m ² or less. When the nonwoven fabric has a basis weight within the above-mentioned range, the nonwoven fabric exhibits advantageous effects such as high bulk, short liquid absorption time, good wetback prevention properties, and good masking properties.

The nonwoven fabric of the embodiment of the present invention preferably has a thickness of 0.20 mm or more and 5.0 mm or less (thickness measured by applying a load of 294 Pa), and a thickness of 0.50 mm or more and 4.0 mm or less. It is more preferable to have a thickness of 1.25 mm or more and 3.60 mm or less. When the nonwoven fabric has a thickness within the above-mentioned range, the nonwoven fabric exhibits the advantageous effects of short liquid absorption time, good wetback prevention properties, good masking properties, and good wearing comfort.

The nonwoven fabric of this embodiment as a whole may have, for example, a fiber density of 0.0100 g/cm ³ or more and 0.100 g/cm ³ or less, and a fiber density of 0.0125 g/cm ³ or more and 0.0600 g/cm ³ or less. It is preferable to have a fiber density of 0.0180 g/cm ³ or more and 0.0400 g/cm ³ or less. The fiber density of the entire nonwoven fabric can be determined from the basis weight and thickness (thickness measured by applying a load of 294 Pa). When the nonwoven fabric has a density within the above range, the nonwoven fabric exhibits the advantageous effects of short liquid absorption time, good wetback prevention properties, good masking properties, and good wearing comfort.

In the nonwoven fabric of the embodiment of the present invention, (i) the rate of change in thickness of the nonwoven fabric is preferably 16% or more, more preferably 16% or more and 70% or less, and preferably 16% or more and 65% or less. It is even more preferable, and particularly preferably 16% or more and 60% or less. The thickness change rate of the nonwoven fabric will be explained in detail in Examples.
In the nonwoven fabric of the present invention, when the rate of change in thickness of the nonwoven fabric is within the above-mentioned range, the wettability of the surface of the nonwoven fabric is good and masking properties are good, which is preferable.

Regarding the strength and elongation of the nonwoven fabric according to the embodiment of the present invention, it is preferable that the tensile strength in the MD direction is 25 N/5 cm or more and 125 N/5 cm or less, and 25 N/5 cm or more and 100 N/5 cm or less. The tensile strength in the CD direction is preferably 3 N/5 cm or more and 30 N/5 cm or less, and more preferably 3 N/5 cm or more and 25 N/5 cm or less. In the nonwoven fabric of the embodiment of the present invention, when the tensile strength of the nonwoven fabric is within the above range, the shape stability of the nonwoven fabric is further improved, which is preferable.
Regarding the strength and elongation of the nonwoven fabric according to the embodiment of the present invention, the elongation rate in the MD direction is preferably 20% or more and 100% or less, more preferably 23% or more and 90% or less. The elongation rate in the CD direction is preferably 20% or more and 120% or less, more preferably 28% or more and 110% or less. In the nonwoven fabric of the embodiment of the present invention, when the elongation rate of the nonwoven fabric is within the above-mentioned range, the flexibility of the nonwoven fabric is further improved, which is preferable.

In the nonwoven fabric of the embodiment of the present invention, the average value of the first liquid absorption time and the second liquid absorption time described in the following examples is preferably less than 50 seconds, and preferably less than 40 seconds. More preferably, less than 25 seconds is even more preferred. When the average value of the first liquid absorption time and the second liquid absorption time is within the above-mentioned range, the nonwoven fabric of the embodiment of the present invention has a suitable usability and is preferable.

In the nonwoven fabric of the embodiment of the present invention, the average value of the first wet back amount and the second wet back amount described in the following examples is preferably 0.7 g or less, and preferably 0.5 g or less. It is more preferable. In the nonwoven fabric of the embodiment of the present invention, when the average value of the first wet back amount and the second wet back amount is within the above-mentioned range, the feeling in use is suitable and it is preferable.

It is preferable that the nonwoven fabric for an absorbent article according to the embodiment of the present invention has the functions of both a top sheet and a diffusion layer of the absorbent article.
In an embodiment of the present invention, an absorbent article including a nonwoven fabric for an absorbent article can be provided. Examples of such absorbent articles include diapers, incontinence pads, napkins, panty liners, and the like. The nonwoven fabric for an absorbent article according to an embodiment of the present invention is placed in an absorbent article, with the first fiber layer being placed closer to the user's skin. The nonwoven fabric for absorbent articles of the embodiment of the present invention can have the functions of both the top sheet and the diffusion layer of the absorbent article, so it can exhibit more stable liquid absorption performance and can be used more easily. Absorbent articles that can be manufactured can be provided.

In another aspect, the present disclosure provides a new method for manufacturing a nonwoven fabric for absorbent articles.
The manufacturing method according to the embodiment of the present invention includes:
An absorbent article that is a nonwoven fabric including a first fiber layer and a second fiber layer located on one main surface of the first fiber layer, the first fiber layer being located closer to the user's skin. A method for producing a nonwoven fabric for use,
A step of manufacturing a first fibrous web containing 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the first fibrous web;
an adhesion step of adhering the fibers of the first fibrous web to each other using the adhesive fibers;
manufacturing a second fibrous web containing cellulose fibers in an amount of 60% by mass or more and 100% by mass or less based on the total mass of the second fibrous web;
a laminating step of laminating the first fibrous web and the second fibrous web to obtain a laminated fibrous web;
An intertwining step of intertwining and integrating the fibers of the first fiber web and the second fiber web with respect to the laminated fiber web,
This is a method for manufacturing a nonwoven fabric for an absorbent article, in which the first fibrous layer including the first fibrous web and the second fibrous layer including the second fibrous web are laminated.

The manufacturing method according to the embodiment of the present invention includes:
A step of manufacturing a first fibrous web containing 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the first fibrous web, and adhering the fibers of the first fibrous web to each other with the adhesive fibers. including an adhesion process.

The first fibrous web can be manufactured by a known method using fibers containing 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the first fibrous web. The form of the first fibrous web may be any form such as a carded web such as a parallel web, a cross web, a semi-random web, and a random web, an air-lay web, and a wet papermaking web. The form of the first fiber web is preferably a parallel web because the surface of the nonwoven fabric becomes smoother. Since the first fibrous web contains 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the first fibrous web, the process such as transportation of the first fibrous web after being subjected to the bonding process is made easier. This is preferable because it gives good results.

The first fibrous web is subjected to a bonding treatment (or bonding step). The adhesive treatment may be, for example, heat treatment (thermal adhesive treatment). According to heat treatment, the component with the lowest melting point (thermal adhesive component) among the resin components that make up the adhesive fibers is melted or softened by heating during heat treatment, making it possible to bond the fibers that make up the fiber web to each other. . The heat treatment may be, for example, hot air processing in which hot air is blown, hot roll processing (e.g., hot embossing roll processing), or heat treatment using infrared rays, but may include hot air processing to improve the texture of the nonwoven fabric. is preferred. The hot air processing treatment may be performed using a device that blows hot air at a predetermined temperature onto the fiber web, such as a hot air through-type heat treatment machine and a hot air blowing type heat treatment machine.

When the bonding process is hot air processing, hot air may be sprayed multiple times. Moreover, when blowing hot air multiple times, it is preferable that the temperature of the second hot air is higher than the temperature of the first hot air.

When the adhesive treatment is a hot air processing treatment, the hot air speed is preferably 0.1 m/min or more and 3.0 m/min or less, from the viewpoint of suppressing fuzzing and improving the softness of the texture. The speed is more preferably 2 m/min or more and 2.5 m/min or less, and even more preferably 0.3 m/min or more and 2.0 m/min or less.

The temperature of the heat treatment may be a temperature at which the component with the lowest melting point (thermal adhesive component) among the resin components constituting the adhesive fiber softens or melts, and may be, for example, a temperature equal to or higher than the melting point of the component. For example, when the component with the lowest melting point among the resin components constituting the adhesive fiber is high-density polyethylene, when performing hot air processing, hot air at a temperature of 130° C. or more and 150° C. or less may be blown. For example, if the component with the lowest melting point among the resin components constituting adhesive fibers is an ethylene-acrylic acid copolymer, hot air at a temperature of 90°C or higher and 140°C or lower may be blown onto the adhesive fiber. In particular, hot air at a temperature of 95° C. or higher and 130° C. or lower may be blown, more particularly hot air at a temperature of 100° C. or higher and 120° C. or lower may be blown. In addition, the temperature of the heat treatment is preferably 0°C or more and 5°C or less higher than the melting point or softening point of the thermal adhesive component, and 1°C or more and 4°C or more, from the viewpoint of suppressing fuzzing and improving the softness of the texture. It is more preferable to set the temperature higher than 0.degree. C., and even more preferably to set the temperature higher than 2.degree. C. or higher and 3.degree. C. or lower.

The adhesion treatment may be performed by irradiation with an electron beam or the like, or by ultrasonic welding. These adhesive treatments also allow the fibers to be adhered to each other using the resin component that constitutes the adhesive fibers.

The manufacturing method according to the embodiment of the present invention includes:
manufacturing a second fibrous web containing cellulose fibers in an amount of 60% by mass or more and 100% by mass or less based on the total mass of the second fibrous web;
a laminating step of laminating the first fibrous web and the second fibrous web to obtain a laminated fibrous web;
The laminated fiber web includes an intertwining step of intertwining and integrating the fibers of the first fiber web and the second fiber web.

The second fibrous web can be manufactured by a known method using fibers containing 60% by mass or more and 100% by mass or less of cellulose fibers based on the total mass of the second fibrous web. The form of the second fibrous web may be any form such as a carded web such as a parallel web, a cross web, a semi-random web, and a random web, an air-lay web, and a wet papermaking web. When the second fiber web is a parallel web, the fibers are oriented in one direction, so they are easily intertwined with the constituent fibers of the first fiber layer, and even if the second fiber layer has a low basis weight, the fibers are oriented in one direction. This is preferred because it is easy to integrate. The form of the second fibrous web may be the same as or different from the form of the first fibrous web, but is preferably the same.

The produced second fibrous web is laminated onto the first fibrous web to produce a laminated fibrous web.

The laminated fibrous web is subjected to an entangling treatment (or entangling step). Examples of the entanglement treatment include water flow entanglement treatment and water vapor flow entanglement treatment, and it is preferable to include either one of these. It is preferable that the entangling step includes hydroentangling treatment. According to these entanglement treatments, the cellulose fibers of the second fiber web can be easily entangled, and a nonwoven fabric having desired physical properties can be obtained.

The manufacturing method of the embodiment of the present invention preferably includes a cooling treatment (or cooling step) after the adhesion treatment (or bonding step) and before the entangling treatment (or entangling step). That is, after the first fibrous web is subjected to the adhesive treatment and before the lamination treatment, and/or after the first fibrous web and the second fibrous web are subjected to the lamination treatment. In this case, it is preferable that the first fiber web and/or the laminated fiber web be subjected to a cooling treatment (or a cooling step) before the laminated fiber web is subjected to the entangling treatment. Examples of the cooling step include air cooling or water cooling. If the first fibrous web is not sufficiently cooled after being subjected to the adhesive treatment, the adhesive components of the adhesive fibers may be in a softened state. If the nonwoven fabric is subjected to the entanglement treatment in that state, the bonded portion may easily peel off, and the fluffing of the nonwoven fabric may be insufficiently suppressed.

The hydroentanglement treatment of the laminated fiber web can be carried out by placing the laminated fiber web on a support and spraying a columnar water stream onto the laminated fiber web. If the surface of the laminated fiber web is flat and has no irregularities, the support should not have pores with an area of more than 0.2 ^mm2 per pore, and should have no protrusions or patterns. It is preferable to use an unformed support. For example, the support may be a plain weave support of 80 mesh or more and 100 mesh or less.

In the hydroentangling process, for example, a water stream with a water pressure of 1 MPa or more and 15 MPa or less is applied to the fiber web from a nozzle in which orifices with a hole diameter of 0.05 mm or more and 0.5 mm or less are provided at intervals of 0.3 mm or more and 1.5 mm or less. This can be carried out by spraying at least once and at most 5 times on each of the front and back surfaces. The water pressure is preferably 1 MPa or more and 10 MPa or less, more preferably 1 MPa or more and 7 MPa or less.

The hydroentanglement process uses nozzles in which fine orifices from which water jets are placed, for example, at intervals of several millimeters. Also, low entanglement portions in which the degree of intertwining of fibers is low may be formed such that highly entangled portions and low entanglement portions are alternately arranged in a plan view of the nonwoven fabric. When such a nozzle is used, the portions that are hit by the water flow from the orifice form streaks, forming highly entangled portions, and the portions that are not hit by the water flow form low entanglement portions. The thickness of the highly entangled portion tends to be smaller than the thickness of the low entangled portion. By forming highly entangled portions and low entangled portions in a nonwoven fabric, short liquid absorption time and good wetback prevention properties are achieved, and the integration of the first fiber layer and the second fiber layer is strengthened. I can do it.

When using such a nozzle, the orifice diameter of the nozzle may be, for example, 0.05 mm or more and 0.5 mm or less, and the interval between the orifices may be 2 mm or more and 20 mm or less, particularly 3 mm or more and 15 mm or less, More particularly, it may be 4 mm or more and 10 mm or less. If the distance between the orifices is too narrow, the distance between the highly entangled portions will become narrow, that is, the width of the low entangled portions will become narrow, and the liquid absorption time and wetback prevention properties may not be as good. The water pressure of the water flow may be, for example, 1 MPa or more and 10 MPa or less, particularly 2 MPa or more and 8 MPa or less.

When using such a nozzle, the water jet is preferably applied only once to one side of the laminated fibrous web. If a water stream is sprayed multiple times on one surface, or if a water stream is sprayed on both surfaces, the width of the low entanglement portion becomes narrow, and the short liquid absorption time and wetback prevention properties may not be improved.

The support used during the hydroentangling treatment may be a plate-shaped or roll-shaped support, and is preferably a roll-shaped support. When the support is in the form of a roll, the laminated fibrous web is curved, resulting in a lower fiber density in the thickness direction of the laminated fibrous web (or generally in the outward direction of a curved web). When the columnar water stream is injected from the outside, the entanglement due to the columnar water stream progresses relatively easily. In the nonwoven fabric of the embodiment of the present invention, the first fibrous web is subjected to an adhesive treatment, and the laminated fibrous web of the first fibrous web and the second fibrous web is subjected to an entangling treatment.

The hydroentangling treatment preferably includes spraying a columnar water stream from the second fiber web side of the laminated fiber web. This allows the energy of the water stream to be applied efficiently to the second fibrous web, resulting in good entanglement, and while maintaining the bulkiness of the first fibrous web, the integration between the first fibrous web and the second fibrous web becomes stronger. This is preferable because it can be done.

When the entangling treatment is a hydroentangling treatment, the laminated fiber web is preferably subjected to a drying treatment (drying step) after the entangling treatment. The drying process can be performed by hot air processing, etc., in which hot air is blown. The temperature of the drying treatment is preferably lower than the temperature at which the adhesive component (thermal adhesive component) of the adhesive fibers contained in the first fibrous web softens or melts. The temperature of the drying treatment is preferably 10°C or more lower than the melting point or softening point of the thermal adhesive component, more preferably 15°C or more lower, and even more preferably 20°C or lower. . If the adhesive component is not softened or melted again after the entanglement treatment, the bulk of the nonwoven fabric will be difficult to lose, and the texture of the nonwoven fabric will be difficult to harden. Not only the drying treatment but also the processing performed on the laminated fiber web after the entangling treatment is preferably performed at a temperature lower than the temperature at which the adhesive component of the adhesive fibers contained in the first fiber web melts.

When the second fibrous web contains adhesive fibers, after the laminated fibrous web is subjected to the entanglement treatment, it may be subjected to a step of bonding the fibers together using the adhesive fibers of the second fibrous web. In particular, the melting point of the adhesive fibers contained in the second fibrous web is lower than the melting point of the adhesive component of the adhesive fibers contained in the first fibrous web, and the adhesive component of the adhesive fibers contained in the first fibrous web is It is preferable that the adhesive component of the adhesive fibers contained in the second fiber web is melted at a temperature lower than the melting temperature to bond the fibers together.

After the bonding step, the first fibrous web can be wound into a roll. The first fibrous web may be unwound and sent to a lamination process. Further, after the lamination step, the laminated fibrous web can be wound into a roll. The laminated fibrous web may be unwound and sent to an entangling process. However, both the first fiber web and the laminated fiber web can be subjected to the entangling step without being wound up. This maintains the bulk of the first fibrous web, increases the bulk of the first fibrous layer, prevents liquid from coming out to the surface of the first fibrous layer due to liquid return, and improves masking properties. It is preferable because it can be done.

Moreover, the manufacturing method of the embodiment of the present invention includes:
The adhesion step includes a hot air processing treatment that applies hot air to one side of the first fibrous web,
The entangling step includes hydroentangling treatment,
The second fibrous web is laminated on the surface of the first fibrous web that is exposed to hot air,
The hydroentangling treatment can include jetting a water stream from the second fibrous web side first. As a result, the energy of the water stream can be efficiently applied to the second fiber web, resulting in good entanglement, and while maintaining the bulkiness of the first fiber web, the integration between the first fiber web and the second fiber web is strengthened. This is preferable because it can be done.

The nonwoven fabric of the present invention can be suitably used for absorbent articles such as disposable diapers, sanitary napkins, incontinence pads, and panty liners. Furthermore, it has an excellent overall balance of properties and can be used in applications that come into direct contact with human skin, such as top sheets and diffusion layers for absorbent articles. Moreover, since it has excellent color masking properties of the liquid it absorbs, it can be particularly suitably used for sanitary napkins.

Hereinafter, the present invention will be explained specifically and in detail with reference to Examples and Comparative Examples, but these Examples are only one aspect of the present invention, and the present invention is not limited by these examples in any way.

The fibers used to produce the nonwoven fabrics of Examples and Comparative Examples are shown below.
<Adhesive fiber>
Fiber 11: Eccentric core-sheath type composite fiber with a core made of polyethylene terephthalate and a sheath made of high-density polyethylene (melting point: about 133°C), with a fineness of 2.6 dtex, a fiber length of 51 mm, and a three-dimensional crimp with an eccentricity ratio of 25%. (NBF(SH)V (product name) manufactured by Daiwabo Polytech Co., Ltd.)
Fiber 12: Concentric core-sheath type composite fiber with a fineness of 2.4 dtex and a fiber length of 51 mm, with a polylactic acid core and a polybutylene succinate (melting point: approximately 115°C) sheath (NBF manufactured by Daiwabo Polytech Co., Ltd.) (KK)PL (product name))
Fiber 13: Concentric core-sheath type composite fiber with a fineness of 2.0 dtex and a fiber length of 45 mm, with a core made of polyethylene terephthalate and a sheath made of high-density polyethylene (melting point: about 133°C) (NBF manufactured by Daiwabo Polytech Co., Ltd.) SH) (product name))
Fiber 14: Concentric core-sheath type composite fiber with a fineness of 1.35 dtex and a fiber length of 30 mm, with a core made of polyethylene terephthalate and a sheath made of high-density polyethylene (melting point: about 133°C) (NBF manufactured by Daiwabo Polytec Co., Ltd.) SH) (product name))
Fiber 15: Concentric core-sheath type composite fiber with a fineness of 4.4 dtex and a fiber length of 51 mm, with a core made of polyethylene terephthalate and a sheath made of high-density polyethylene (melting point: about 133°C) (NBF manufactured by Daiwabo Polytec Co., Ltd.) SH) (product name))
Fiber 16: Eccentric core-sheath type composite fiber with a core made of polyethylene terephthalate and a sheath made of high-density polyethylene (melting point: about 133°C), with a fineness of 3.3 dtex, a fiber length of 51 mm, and a three-dimensional crimp with an eccentricity ratio of 25%. (NBF(SH)V (product name) manufactured by Daiwabo Polytech Co., Ltd.)
Fiber 17: Splitable conjugate fiber made of a combination of polypropylene and high-density polyethylene, with 8 divisions, a fineness of 1.8 dtex, and a fiber length of 45 mm (the fineness of the fiber with the smallest fineness among the fibers formed by splitting is 0.275dtex) (DFS-7 (product name) manufactured by Daiwabo Polytec Co., Ltd.)

<Cellulose fiber>
Fiber 21: Viscose rayon fiber with a fineness of 2.2 dtex, a fiber length of 38 mm, and a trilobal (Y-shaped) fiber cross section (Corona RBA (product name) manufactured by Daiwabo Rayon Co., Ltd.)
Fiber 22: Viscose rayon fiber with a fineness of 2.2 dtex, a fiber length of 51 mm, and a chrysanthemum-shaped fiber cross section (Corona CD (product name) manufactured by Daiwabo Rayon Co., Ltd.)
Fiber 23: Viscose rayon fiber with a fineness of 3.3 dtex, a fiber length of 51 mm, and a chrysanthemum-shaped fiber cross section (Corona CD (product name) manufactured by Daiwabo Rayon Co., Ltd.)

<Manufacture of nonwoven fabric of Example 1>
A fibrous web was produced using only Fiber 11 and using a parallel card machine. The basis weight of this fibrous web was approximately 30 g/m ² .
This fibrous web was heated at 135° C. for about 5 seconds using a hot air penetration type heat treatment machine to obtain an air-through nonwoven fabric serving as the first fibrous layer in which the fibers were thermally bonded (adhesive treatment) to each other by the sheath component of the fibers 11. .
A fibrous web serving as the second fibrous layer having a basis weight of approximately 30 g/m ² was produced using only the fibers 21 using a parallel card machine, and was laminated on the air-through nonwoven fabric to form a laminate.
The above-mentioned laminate was placed on a plain weave net having a warp diameter of 0.132 mm, a weft diameter of 0.132 mm, and a mesh count of 90 meshes. While the laminate was traveling at a speed of 4 m/min, a columnar water stream with a water pressure of 3.0 MPa was injected onto the surface of the laminate on the fiber web (second fibrous layer) side using a water supply device. The nozzle of the water supply device was provided with orifices having a hole diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the laminate and the orifice was 15 mm. Thereafter, a columnar water stream at a water pressure of 3.0 MPa was similarly sprayed onto the surface of the laminate on the air-through nonwoven fabric (first fiber layer) side using a water supply device.
This laminate was dried at 80° C. using a hot air penetration type heat treatment machine to obtain the nonwoven fabric of Example 1. The first fiber layer and the second fiber layer were integrated by intertwining the fibers. Further, no openings were formed in the first fiber layer and the second fiber layer.

<Manufacture of nonwoven fabric of Example 2>
A nonwoven fabric of Example 2 was obtained in the same manner as in Example 1 except that fiber 21 was changed to fiber 22.

<Manufacture of nonwoven fabric of Example 3>
A nonwoven fabric of Example 3 was obtained in the same manner as in Example 1 except that fiber 21 was changed to fiber 23 in Example 1.

<Manufacture of nonwoven fabric of Example 4>
Example 1 was carried out in the same manner as in Example 1, except that fiber 11 was changed to fiber 12 and the temperature of the hot air through-type heat treatment machine was changed to 128 ° C. in the step of obtaining an air-through nonwoven fabric serving as the first fiber layer. A nonwoven fabric of Example 4 was obtained.

<Manufacture of nonwoven fabric of Example 5>
A nonwoven fabric of Example 5 was obtained in the same manner as in Example 1 except that fiber 11 was changed to fiber 13.

<Manufacture of nonwoven fabric of Example 6>
A nonwoven fabric of Example 6 was obtained in the same manner as in Example 1 except that fiber 11 was changed to fiber 14.

<Manufacture of nonwoven fabric of Example 7>
A nonwoven fabric of Example 7 was obtained in the same manner as in Example 1 except that fiber 11 was changed to fiber 15 in Example 1.

<Manufacture of nonwoven fabric of Example 8>
A nonwoven fabric of Example 8 was obtained in the same manner as in Example 1 except that fiber 11 was changed to fiber 16.

<Manufacture of nonwoven fabric of Example 9>
A nonwoven fabric of Example 9 was obtained in the same manner as in Example 1 except that fiber 11 was changed to fiber 17.

<Manufacture of nonwoven fabric of Example 10>
In Example 1, the water pressure of the columnar water stream injected onto the surface of the fibrous web (second fibrous layer) side of the laminate was changed to 2.0 MPa, and then the air-through nonwoven fabric (first fibrous layer) side of the laminate was changed to 2.0 MPa. When injecting a columnar water stream onto a surface, the nozzle of the water supply device is changed to one in which orifices with a hole diameter of 0.2 mm are provided at 7.0 mm intervals, and the water pressure of the columnar water stream is increased to 6. A nonwoven fabric of Example 10 was obtained in the same manner as Example 1 except that the pressure was changed to 0 MPa.

<Manufacture of nonwoven fabric of Example 11>
A nonwoven fabric of Example 11 was obtained in the same manner as in Example 10 except that fiber 11 was changed to fiber 14.

<Manufacture of nonwoven fabric of Example 12>
A nonwoven fabric of Example 12 was obtained in the same manner as in Example 10, except that fiber 11 was changed to fiber 15 in Example 10.

<Manufacture of nonwoven fabric of Example 13>
A nonwoven fabric of Example 13 was obtained in the same manner as in Example 10, except that fiber 11 was changed to fiber 13.

<Manufacture of nonwoven fabric of Example 14>
In Example 1, instead of spraying a columnar water stream onto the surface of the laminate on the air-through nonwoven fabric (first fibrous layer) side, the columnar water stream was sprayed onto the surface of the laminate on the fibrous web (second fibrous layer) side. A nonwoven fabric of Example 14 was obtained in the same manner as Example 1 except that the columnar water stream was again jetted.

<Manufacture of nonwoven fabric of Example 15>
Example 15 was carried out in the same manner as in Example 1, except that the basis weight of the first fiber layer was changed to about 40 g/m ² and the basis weight of the second fiber layer was ^changed to about 20 g/m 2. A nonwoven fabric was obtained.

<Manufacture of nonwoven fabric of Example 16>
In Example 1, except that the fiber 11 was changed to fiber 13, the basis weight of the first fiber layer was changed to about 20 g/m ² , and the basis weight of the second fiber layer was changed to about 40 g/m ² . A nonwoven fabric of Example 16 was obtained in the same manner as in Example 1.

<Manufacture of nonwoven fabric of Comparative Example 1>
A fibrous web serving as the first fibrous layer was manufactured using only Fiber 11 and using a parallel card machine. The basis weight of this fibrous web was approximately 30 g/m ² .
Using only the fiber 21, a parallel card machine is used to produce a fiber web that will become the second fiber layer and has a basis weight of about 30 g/ ^m2 , and is laminated on top of the fiber web that will become the first fiber layer. As a body.
The above-mentioned laminate was placed on a plain weave net having a warp diameter of 0.132 mm, a weft diameter of 0.132 mm, and a mesh count of 90 meshes. While the laminate was traveling at a speed of 4 m/min, a columnar water stream with a water pressure of 3.0 MPa was injected onto the surface of the laminate on the second fiber layer side using a water supply device. The nozzle of the water supply device was provided with orifices having a hole diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the laminate and the orifice was 15 mm. Thereafter, a columnar water stream with a water pressure of 3.0 MPa was injected onto the surface of the laminate on the first fiber layer side using a water supply device in the same manner.
This laminate was heated at 135°C for about 5 seconds using a hot air penetration type heat treatment machine, and a drying treatment and thermal adhesion (adhesion treatment) between the fibers were performed using the sheath component of the fibers 11. Obtained.

<Manufacture of nonwoven fabric of Comparative Example 2>
A fibrous web was produced using only Fiber 11 and using a parallel card machine. The basis weight of this fibrous web was approximately 30 g/m ² .
This fibrous web was heated at 135° C. for about 5 seconds using a hot air through-type heat treatment machine to obtain an air-through nonwoven fabric in which the fibers were thermally bonded (adhered) to each other by the sheath component of the fibers 11.
The air-through nonwoven fabric described above was placed on a plain weave net having a warp diameter of 0.132 mm, a weft diameter of 0.132 mm, and a mesh count of 90 meshes. While the air-through nonwoven fabric was traveling at a speed of 4 m/min, a columnar water stream with a water pressure of 3.0 MPa was injected onto the surface of the air-through nonwoven fabric using a water supply device. The nozzle of the water supply device was provided with orifices having a hole diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the air-through nonwoven fabric and the orifice was 15 mm. After that, a columnar water stream with a water pressure of 3.0 MPa was similarly injected onto the opposite surface of the air-through nonwoven fabric using a water supply device, and a drying process was performed at 80 ° C. using a hot air through-type heat treatment machine. A nonwoven fabric serving as the first fiber layer was obtained.
Next, a fibrous web having a basis weight of about 30 g/m ² was produced using only the fiber 21 using a parallel card machine.
The above-mentioned fibrous web was placed on a plain weave net having a warp diameter of 0.132 mm, a weft diameter of 0.132 mm, and a mesh count of 90 meshes. While the fibrous web was traveling at a speed of 4 m/min, a columnar water stream with a water pressure of 3.0 MPa was injected onto the surface of the fibrous web using a water supply device. The nozzle of the water supply device was provided with orifices having a hole diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the fibrous web and the orifice was 15 mm. After that, a columnar water stream with a water pressure of 3.0 MPa is similarly injected onto the opposite surface of the fibrous web using a water supply device, and a drying process is performed at 80 ° C. using a hot air through-type heat treatment machine. A nonwoven fabric serving as the second fiber layer was obtained.
A nonwoven fabric serving as the first fibrous layer was laminated on the nonwoven fabric serving as the second fibrous layer to obtain a nonwoven fabric (laminate) of Comparative Example 2 in which the nonwoven fabrics were not integrated.

<Manufacture of nonwoven fabric of Comparative Example 3>
A fibrous web was produced using only Fiber 11 and using a parallel card machine. The basis weight of this fibrous web was approximately 60 g/m ² .
This fibrous web was heated at 135° C. for about 5 seconds using a hot air through-type heat treatment machine to obtain an air-through nonwoven fabric of Comparative Example 3 in which the fibers were thermally bonded (adhesive treatment) to each other using the sheath component of the fibers 11. Note that Comparative Example 3 is not a laminated nonwoven fabric, but a nonwoven fabric consisting only of the first fiber layer.

Evaluation of the nonwoven fabric was performed as follows.
<Nonwoven fabric thickness, thickness change rate, density>
Using a thickness measuring machine (THICKNESS GAUGE model CR-60A (trade name) manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), the thickness of the nonwoven fabric was measured with a load of 294 Pa or 1.96 kPa applied to the nonwoven fabric. .
The thickness change rate was calculated based on the following formula from the thickness under a load of 294 Pa (P1) and the thickness under a load of 1.96 kPa (P2).
Thickness change rate (%) = [(P1-P2)/P1] x 100
The density of the nonwoven fabric was calculated based on the basis weight of the nonwoven fabric and the thickness of the nonwoven fabric obtained by applying a load of 294 Pa.

<Strong elongation>
The strength and elongation was measured according to JIS L 1913:2010 6.3. A tensile test was conducted using a constant speed tension type tensile testing machine under the conditions that the sample piece (nonwoven fabric) had a width of 5 cm, a grip interval of 10 cm, and a tensile speed of 30±2 cm/min. The load value (tensile strength) at cutting, elongation rate, and stress at 10% elongation were measured. The tensile test was conducted with the longitudinal direction (MD direction) and the lateral direction (CD direction) of the nonwoven fabric as the tensile directions. The evaluation results were all shown as the average of the values measured for three samples.

<Liquid absorption time, wet back amount, masking property>
The liquid absorption performance was evaluated using sanitary napkins that are actually on sale.
(1) Peel off the top sheet and two sheets located under the top sheet of the sanitary napkin (manufactured by P&G, product name: “Whisper Pure Naked (Ultra Slim Daytime/Daytime Use 22cm)”) and absorb the napkin. The body was exposed, and a nonwoven fabric (nonwoven fabric of Example or Comparative Example) cut into 220 mm x 80 mm (vertical direction x horizontal direction) was placed on top of the absorbent body. The nonwoven fabric was arranged so that the second fiber layer was in contact with the absorbent body. Place a plate with an injection barrel on top of the first fiber layer (a two-stage cylindrical piece with a height of 75 mm, an inner diameter of 25 mm at the top of the barrel, and an inner diameter of 10 mm at the bottom of the barrel), and place 5.0 cc into the injection barrel of the plate with an injection barrel. Artificial menstrual blood (viscosity 8 mPa·s, temperature 37°C) was injected. The time required for the liquid to disappear from the surface of the nonwoven fabric (liquid absorption time) was measured. It can be said that the shorter the liquid absorption time, the higher the liquid absorption rate. The composition of the artificial menstrual blood is 12.61% by mass of glycerin, 84.88% by mass of distilled water, 0.45% by mass of CMC (sodium carboxymethylcellulose), 0.97% by mass of NaCl (sodium chloride), and 0.97% by mass of Na2CO3 (carbonate). Sodium) was 1.04% by mass, and red powder was 0.06% by mass.

(2) When measuring the liquid absorption time, 10 minutes after the injection of artificial menstrual blood, a filter paper (manufactured by Toyo Roshi Co., Ltd., trade name ADVANTEC (registered trademark) No. 2, 10 cm x A weight of 1 kg (shape: square, 10 cm x 10 cm) was placed on top of the filter paper. The filter paper was taken out 20 seconds after the weight was placed on it, the mass of the filter paper that had absorbed the artificial menstrual blood was measured, and the mass of the filter paper before it was placed on the nonwoven fabric was subtracted to calculate the amount of wet back. It can be said that the smaller the amount of wet back, the less likely wet back will occur.

(3) The second liquid absorption time was measured by injecting artificial menstrual blood 25 minutes after the first artificial menstrual blood injection. The amount of artificial menstrual blood, etc. was carried out under the same conditions as the first time. The second wet back amount measurement was performed 10 minutes after the second injection of artificial menstrual blood in the same manner as the first wet back amount measurement.

To measure the liquid absorption time (wet back amount), prepare five samples of the nonwoven fabric of one example or comparative example, and calculate the average value of the liquid absorption time (wet back amount) measured for each of the five samples. The liquid absorption time (wet back amount) was taken as the example or comparative example.

The liquid absorption time was evaluated in four stages based on the following numerical criteria.
◎: The average value of the first and second times is less than 25 seconds ○: The average value of the first and second times is 25 seconds or more and less than 40 seconds △: The average value of the first and second times is 40 seconds or more and 50 Less than seconds ×: The average value of the first and second times is 50 seconds or more

The wet back amount was evaluated in three stages based on the following numerical criteria.
◎: The average value of the first and second times is 0.5 g or less. ○: The average value of the first and second times is greater than 0.5 g and 0.7 g or less. ×: The average value of the first and second times is 0.5 g or less. greater than 7g

Masking properties were determined by one photograph of the surface of the nonwoven fabric taken between the time of measuring the first liquid absorption time and before measuring the amount of wet back, and the measurement of the amount of wet back after the second measurement of liquid absorption time. The color depth of the artificial menstrual blood visible on the surface of the nonwoven fabric from one photograph of the surface of the nonwoven fabric taken during the previous period was evaluated using the following criteria. There are a total of 10 photos of 5 samples of the nonwoven fabric of one example or comparative example, and among the 5 photos each from the first and second liquid absorption performance measurements, the color of artificial menstrual blood was the highest. One photo of each was selected that looked faint (the artificial menstrual blood was hidden). More specifically, regarding the color of the artificial menstrual blood visible from the surface of the nonwoven fabric, one photograph was selected in which the area of the darkly colored part was the smallest. A photograph of the surface of the nonwoven fabric sample of Example 7 is shown in FIG. A photograph of the surface of the nonwoven fabric sample of Comparative Example 3 is shown in FIG.
○: For both the first and second times, there is no part with the same color depth as the artificial menstrual blood used. △: For the first or second time, there is no part with the same color depth as the artificial menstrual blood used. There is a dark part ×: Both the first and second times, there is a part that is as dark as the color of the artificial menstrual blood used.

<Fuzz>
The fluff was evaluated by observing the surface of the nonwoven fabric (first fiber layer side) according to the following criteria.
○: Good (very little fuzz)
△: Normal (fuzz is not noticeable)
×: Bad (some fluff is noticeable)

＊）比較例２の実測目付、密度、厚さ、強伸度については、第１繊維層及び第２繊維層それぞれの数値を記載している。前の数値が第１繊維層の数値であり、後の数値が第２繊維層の数値である。比較例２では第１繊維層と第２繊維層とは交絡によって一体化されていない。

*) Regarding the measured basis weight, density, thickness, and strength and elongation of Comparative Example 2, the values are listed for each of the first fiber layer and the second fiber layer. The first value is the value for the first fiber layer, and the second value is the value for the second fiber layer. In Comparative Example 2, the first fiber layer and the second fiber layer were not integrated by intertwining.

The nonwoven fabrics for absorbent articles of Examples 1 to 16 are nonwoven fabrics including a first fibrous layer and a second fibrous layer located on one main surface of the first fibrous layer,
the first fiber layer includes adhesive fibers,
The first fibrous layer contains 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fibrous layer,
the second fiber layer includes cellulose fibers,
The second fibrous layer contains 60% by mass or more and 100% by mass or less of the cellulose fibers based on the total mass of the second fibrous layer,
In the first fiber layer, fibers are bonded to each other by the adhesive fibers,
The first fiber layer and the second fiber layer are integrated by intertwining the fibers,
The nonwoven fabric has a thickness change rate of 16% or more,
Since the first fiber layer is placed closer to the user's skin,
Excellent in fluff, liquid absorption time, amount of wet back, and masking properties.
It can be used as a nonwoven fabric that has the properties of both a top sheet and a diffusion layer. Therefore, the nonwoven fabrics for absorbent articles of Examples 1 to 16 can be suitably used to manufacture absorbent articles, and the manufacturing method thereof can be simplified.

In Comparative Example 1, the thickness change rate of the nonwoven fabric was not 16% or more, and the adhesive fibers contained in the first fiber layer and the cellulose fibers contained in the second fiber layer were bonded, and the masking property was poor. Inferior. A nonwoven fabric with poor masking properties will have a relatively large amount of artificial menstrual blood on the surface of the nonwoven fabric on the first fiber layer side, resulting in a wet sensation when the skin touches it, resulting in poor usability.
In Comparative Example 2, the adhesive fibers of the first fibrous layer have adhesive points and are further intertwined, but are not integrated with the second fibrous layer and are inferior in liquid absorption time.
Comparative Example 3 does not have the second fiber layer containing cellulose fibers and is inferior in wet back amount and masking properties.

The nonwoven fabric for absorbent articles according to the embodiment of the present invention can be used as a nonwoven fabric that has both the properties of a top sheet and a diffusion layer. Therefore, the nonwoven fabric for absorbent articles of the present invention can be suitably used to manufacture absorbent articles, and the manufacturing method thereof can be simplified.

This specification includes the following forms.
1.
A nonwoven fabric comprising a first fiber layer and a second fiber layer located on one main surface of the first fiber layer,
the first fiber layer includes adhesive fibers,
The first fibrous layer contains 60% by mass or more and 100% by mass or less of the adhesive fibers based on the total mass of the first fibrous layer,
the second fiber layer includes cellulose fibers,
The second fibrous layer contains 60% by mass or more and 100% by mass or less of the cellulose fibers based on the total mass of the second fibrous layer,
In the first fiber layer, fibers are bonded to each other by the adhesive fibers,
The first fiber layer and the second fiber layer are integrated by intertwining the fibers,
the first fibrous layer is located closer to the user's skin;
Satisfying either (i) or (ii) below,
(i) The thickness change rate of the nonwoven fabric measured by the following measurement method is 16% or more.
(ii) The fibers included in the second fiber layer are not bonded by the adhesive fibers.
Nonwoven fabric for absorbent articles.
[Thickness change rate]
Using a thickness measuring machine, the thickness of the nonwoven fabric was measured with a load of 294Pa or 1.96kPa applied to the nonwoven fabric, and the thickness at a load of 294Pa (P1) and the thickness at a load of 1.96kPa (P2) were measured. Calculated based on the following formula.
Thickness change rate (%) = [(P1-P2)/P1] x 100
2.
1. The nonwoven fabric for absorbent articles as described in 1 above, wherein the adhesive fiber has a fineness of 1.0 dtex or more and 5.0 dtex or less.
3.
3. The nonwoven fabric for absorbent articles according to 1 or 2 above, wherein the adhesive fiber includes a core-sheath composite fiber.
4.
4. The nonwoven fabric for an absorbent article according to any one of 1 to 3 above, wherein the adhesive fiber includes an eccentric core-sheath type conjugate fiber.
5.
5. The nonwoven fabric for absorbent articles according to any one of 1 to 4 above, wherein the cellulose fiber has a fineness of 1.0 dtex or more and 5.0 dtex or less.
6.
6. The nonwoven fabric for absorbent articles according to any one of 1 to 5 above, wherein the cellulose fibers include multilobal cellulose fibers having a fiber cross section of three or more leaves.
7.
7. The nonwoven fabric for absorbent articles according to any one of items 1 to 6 above, which functions as both a top sheet and a diffusion layer of the absorbent article.
8.
An absorbent article comprising the nonwoven fabric for absorbent articles according to 7 above.
9.
An absorbent article that is a nonwoven fabric including a first fiber layer and a second fiber layer located on one main surface of the first fiber layer, the first fiber layer being located closer to the user's skin. A method for producing a nonwoven fabric for use,
Producing a first fibrous web containing 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the web;
an adhesion step of adhering the fibers of the first fibrous web to each other using the adhesive fibers;
producing a second fibrous web containing cellulose fibers in an amount of 60% by mass or more and 100% by mass or less based on the total mass of the web;
a laminating step of laminating the first fibrous web and the second fibrous web to obtain a laminated fibrous web;
An intertwining step of intertwining and integrating the fibers of the first fiber web and the second fiber web with respect to the laminated fiber web,
A method for producing a nonwoven fabric for an absorbent article, wherein the first fibrous web becomes the first fibrous layer, and the second fibrous web becomes the second fibrous layer.
10.
10. The method for producing a nonwoven fabric for absorbent articles according to 9 above, wherein the entangling step includes hydroentangling treatment.
11.
11. The method for producing a nonwoven fabric for absorbent articles as described in 9 or 10 above, wherein the adhesion step includes hot air processing.
12.
The nonwoven fabric for absorbent articles according to any one of 9 to 11 above, wherein the first fibrous web or the laminated fibrous web is subjected to an entangling process without winding the first fibrous web or the laminated fibrous web into a roll after the adhesion process. manufacturing method.
13.
The adhesion step includes a hot air processing treatment that applies hot air to one side of the first fibrous web,
The entangling step includes hydroentangling treatment,
The second fibrous web is laminated on the surface of the first fibrous web that is exposed to hot air,
The method for producing a nonwoven fabric for an absorbent article according to any one of items 9 to 12 above, wherein the hydroentangling treatment includes spraying a water stream from the second fibrous web side first.

Claims (2)

An absorbent article that is a nonwoven fabric including a first fiber layer and a second fiber layer located on one main surface of the first fiber layer, the first fiber layer being located closer to the user's skin. A method for producing a nonwoven fabric for use,
Producing a first fibrous web containing 60% by mass or more and 100% by mass or less of adhesive fibers based on the total mass of the web;
an adhesion step of adhering the fibers of the first fibrous web to each other using the adhesive fibers;
producing a second fibrous web containing cellulose fibers in an amount of 60% by mass or more and 100% by mass or less based on the total mass of the web;
a laminating step of laminating the first fibrous web and the second fibrous web to obtain a laminated fibrous web;
An intertwining step of intertwining and integrating the fibers of the first fiber web and the second fiber web with respect to the laminated fiber web,
The adhesion step includes a hot air processing treatment that applies hot air to one side of the first fibrous web,
The entangling step includes hydroentangling treatment,
The second fibrous web is laminated on the surface of the first fibrous web that is exposed to hot air,
The hydroentangling treatment includes spraying a water stream from the second fibrous web side first,
A method for producing a nonwoven fabric for an absorbent article, wherein the first fibrous web becomes the first fibrous layer, and the second fibrous web becomes the second fibrous layer. The method for producing a nonwoven fabric for an absorbent article according to claim 1 , wherein the laminated fiber web is subjected to an intertwining step without winding the first fiber web or the laminated fiber web into a roll after the bonding step.