JP2023110380A - Nonwoven fabric for absorbent article, manufacturing method thereof and absorbent article - Google Patents

Abstract

To provide a nonwoven fabric for absorbent article excellent in liquid-absorbing speed and wet back property, a manufacturing method thereof, and an absorbent article.SOLUTION: A nonwoven fabric for absorbent article has a first fiber layer and a second fiber layer that is located on one main surface of the first fiber layer and different from the first fiber layer. The first fiber layer and the second fiber layer are integrated by entanglement of fibers with each other. The first fiber layer includes more than 30 mass% and 90 mass% or less of water-repellent cellulose fiber and 10 mass% or more of hydrophilic fiber based on the total mass of the first fiber layer. The second fiber layer includes 5 mass% or more of hydrophilic fiber based on the total mass of the second fiber layer. A contact angle θ1 between water and the first fiber layer surface and a contact angle θ2 between the water and the second fiber layer surface before water permeates are 75° or more.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present disclosure relates to nonwoven fabrics for absorbent articles, methods of manufacturing the same, and absorbent articles.

Various absorbent articles are on the market, such as disposable diapers, sanitary napkins, incontinence pads and pantiliners. A nonwoven fabric having a two-layer structure has been proposed as a sheet that is used in these absorbent articles and that constitutes the part that comes into contact with the skin of the wearer. For example, Patent Document 1 discloses a sheet having a first layer and a second layer, wherein the first layer that touches the user's skin is made of hydrophobic artificial cellulose fiber or polyester fiber. ing.

Japanese Patent Application Publication No. 2015-507977

The nonwoven fabric of Patent Literature 1 has excellent wet back properties (rewet properties) because the first layer on the skin side is made of hydrophobic fibers. On the other hand, the liquid absorption speed is slow.

An object of the present disclosure is to provide a nonwoven fabric for absorbent articles that is excellent in liquid absorption rate and wetback property, a method for producing the same, and absorbent articles.

The present disclosure comprises a first fibrous layer and a second fibrous layer located on one major surface of said first fibrous layer and different from said first fibrous layer, wherein said first fibrous layer and said second The fiber layers are integrated by entangling the fibers, and the first fiber layer contains more than 30% by mass and not more than 90% by mass of water-repellent cellulose fibers based on the total mass of the first fiber layer, and is hydrophilic. 10% by mass or more of hydrophilic fibers, the second fiber layer contains 5% by mass or more of hydrophilic fibers based on the total mass of the second fiber layer, and water and the first A contact angle θ1 with the fiber layer surface and a contact angle θ2 between water and the second fiber layer surface are both 75° or more to provide a nonwoven fabric for absorbent articles.

The present disclosure also comprises a first fibrous layer and a second fibrous layer located on one major surface of said first fibrous layer and different from said first fibrous layer, wherein said first fibrous layer and said first The two fiber layers are integrated by entangling the fibers, and the first fiber layer contains more than 30% by mass and 90% by mass or less of water-repellent cellulose fibers based on the total mass of the first fiber layer, Further, the hydrophilic fiber is contained in an amount of 10% by mass or more and less than 70% by mass, and the second fiber layer contains 5 masses of hydrophobic fibers and a) hydrophilic cellulose fibers based on the total mass of the second fiber layer. % or more and 40% or less by mass, b) containing 40% or more and 90% or less by mass of hydrophilic synthetic fibers based on the total mass of the second fiber layer, or (c) hydrophilic synthetic fibers, Provided is a nonwoven fabric for absorbent articles containing 30% by mass or more and 90% by mass or less based on the total mass of two fiber layers.

The present disclosure also provides an absorbent article comprising the nonwoven fabric for absorbent articles described above.

The present disclosure also provides for preparing the first fibrous web, which contains more than 30% by mass of water-repellent cellulose fibers and 10% by mass or more of hydrophilic fibers, based on the total mass of the first fibrous web. (b ) containing 40% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fiber layer, or (c) containing hydrophilic synthetic fibers based on the total mass of the second fiber layer Producing the second fiber web containing 30% by mass or more and 90% by mass or less, producing a laminated fiber web by overlapping the first fiber web and the second fiber web, and the laminated fiber web and subjecting the fibers to an entangling treatment using a high-pressure fluid stream to entangle the fibers.

INDUSTRIAL APPLICABILITY According to the present disclosure, a nonwoven fabric for absorbent articles excellent in liquid absorption rate and wetback property, a method for producing the same, and an absorbent article are provided.

From the viewpoint of SDGs, industrial products are required to be derived from biomass (plants), biodegradable, and recyclable. Nonwoven fabrics for the surface of absorbent articles (hereinafter referred to as topsheets) are no exception. Furthermore, since this top sheet comes into contact with human skin, it is important for the user that it is made of a safe and secure material. Materials satisfying such requirements include natural fibers such as cotton and lyocell. However, it is difficult to satisfy the performance required for the top sheet by using only these natural fibers.

The performance required for the top sheet typically includes a high liquid absorption rate and excellent wet back properties. Wet-back properties are properties that prevent liquid once taken into the absorbent article from returning to the surface of the top sheet. Excellent wet-back property means that the liquid is difficult to return. The liquid absorption speed is likely to be affected by the hydrophilicity of the topsheet, and the wet back property is likely to be affected by the water repellency of the topsheet.

In addition, the topsheet is also required to be liquid-tight. Leakage occurs when the absorbent article fails to absorb enough liquid. Leakage is susceptible to the hydrophilicity of the first and second fibrous layers. If the water repellency of the surface of the first fiber layer is excessively high, the liquid cannot permeate the inside of the first fiber layer and stays on the surface of the first fiber layer. If the water repellency of the surface of the second fibrous layer is excessively high, liquid will stay between the first and second fibrous layers, resulting in a decrease in absorbency. These results in liquid leakage. In the latter case, deterioration of wet back property is also caused.

Since natural fibers are hydrophilic, the top sheet formed from them has a relatively high liquid absorption speed but is inferior in wetback property, contrary to Patent Document 1. It has also been proposed to apply a water-repellent agent to a natural fiber sheet to improve the wetback property, but this results in an increase in the number of steps.

The present disclosure is a nonwoven fabric suitable as a surface sheet (topsheet) of an absorbent article, which has at least a first fibrous layer and a second fibrous layer. The skin-contacting surface is the first fibrous layer and includes water-repellent cellulose fibers. The first fibrous layer is also the first layer contacted by the liquid to be absorbed. The water-repellent cellulose fiber imparts hydrophobicity to the first fiber layer, and furthermore gives the user a sense of security and an impression of safety.

By using a specific amount of hydrophilic fibers as the material of the first fiber layer, the first fiber layer has both moderate hydrophilicity and water repellency. Since the first fiber layer has moderate hydrophilicity, the liquid absorption rate is increased and liquid leakage is suppressed. Due to the moderate hydrophobicity of the first fiber layer, the liquid quickly permeates the first fiber layer without remaining in the first fiber layer. As a result, the wet-back property is improved, and the uncomfortable feeling of wetness is less likely to occur.

The hydrophilicity of the second fiber layer, which is the inner layer, is also important for achieving both excellent liquid absorption speed and excellent wet back properties. Liquid passing through the first fiber layer passes through the second fiber layer and is absorbed and dispersed in an absorption distribution layer (ADL) inside thereof. Therefore, the second fiber layer is required to have water repellency that allows liquid to pass through quickly. When the hydrophilicity of the second fiber layer is high, liquid tends to stay inside the second fiber layer. As a result, the liquid tends to return, and the wet-back property tends to decrease. On the other hand, if the hydrophobicity of the second fiber layer is too high, liquid leakage may occur.

In the first embodiment of the present disclosure, the degree of hydrophilicity of each fiber layer is defined by setting the contact angles of both the first and second fiber layers to 75° or more. In the second embodiment of the present disclosure, the degree of hydrophilicity of each fiber layer is defined by specifying the configuration of each of the first and second fiber layers. As a result, both excellent liquid absorption speed and excellent wet back properties can be achieved without the need for post-processing.

That is, the nonwoven fabric for absorbent articles according to the first embodiment includes a first fiber layer and a second fiber layer located on one main surface of the first fiber layer and different from the first fiber layer. The first fiber layer and the second fiber layer are integrated by entangling the fibers, and the first fiber layer contains water-repellent cellulose fibers based on the total mass of the first fiber layer. More than 30% by mass and 90% by mass or less, 10% by mass or more of hydrophilic fibers, the second fiber layer contains 5% by mass or more of hydrophilic fibers based on the total mass of the second fiber layer, and water The contact angle θ1 between water and the surface of the first fiber layer and the contact angle θ2 between water and the surface of the second fiber layer are both 75° or more before permeation of water.

A nonwoven fabric for absorbent articles according to a second embodiment includes a first fiber layer and a second fiber layer located on one main surface of the first fiber layer and different from the first fiber layer, The first fiber layer and the second fiber layer are integrated by entangling the fibers, and the first fiber layer contains 30 mass of water-repellent cellulose fiber based on the total mass of the first fiber layer. % and 90% by mass or less and 10% by mass or more and less than 70% by mass of hydrophilic fibers, and the second fiber layer contains hydrophobic fibers and (a) hydrophilic cellulose fibers, the second fibers 5% by mass or more and 40% by mass or less based on the total mass of the layer, (b) 40% by mass or more and 90% by mass or less of the hydrophilic synthetic fiber based on the total mass of the second fiber layer, or ( c) 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fiber layer;

Absorbent articles have a variety of uses, ranging from absorbing small amounts of high-viscosity liquids, such as menstrual blood, to absorbing large amounts of low-viscosity liquids, such as urine. The topsheet is also required to absorb such liquids of various viscosities and amounts quickly and without backflow. According to the nonwoven fabric for absorbent articles according to the present disclosure, both excellent liquid absorption speed and excellent wet back properties are achieved regardless of the viscosity and amount of liquid to be absorbed.

[Nonwoven fabric for absorbent articles]
First, the configuration common to each embodiment will be described.
A nonwoven fabric for absorbent articles according to the present disclosure includes a first fibrous layer and a second fibrous layer. Hereinafter, the nonwoven fabrics for absorbent articles according to the first and second embodiments may simply be collectively referred to as nonwoven fabrics.

Nonwoven fabrics are defined in JIS L 0222 as "fiber sheets, webs, or batts in which the fibers are oriented in one direction or randomly, and the fibers are bonded by entangling, fusion, and/or adhesion. , excluding paper, woven fabrics, knitted fabrics, tufts and crepe felts.”

In the nonwoven fabric, each fiber layer is laminated and integrated at least by entangling the fibers. As a result, the liquid that has permeated the first fiber layer can quickly enter the second fiber layer, so that it is suppressed from staying between the layers. Furthermore, the liquid that has permeated the first fiber layer is prevented from flowing back without entering the second fiber layer and leaking out to the surface of the first fiber layer.

Each fibrous layer prior to lamination may be a nonwoven or a precursor to a nonwoven. A nonwoven precursor is a fibrous sheet, web or batt in which the fibers are unidirectionally or randomly oriented, but the fibers are not bonded together. The method for producing each fiber layer before lamination is not particularly limited. Each fiber layer (web) used in the production of nonwoven fabrics may be a precursor of nonwoven fabrics produced by a carded method, an airlaid method, a wet method, or the like, and may be hydroentangled (spunlaced), spunbonded, or It may be a nonwoven fabric produced by a wet method or the like.

(Metsuke)
From the viewpoint of liquid absorption rate, the first fiber layer is preferably less dense than the second fiber layer. From the perspective of liquid permeability, it is desirable that the second fibrous layer not be excessively dense. Although it depends on the thickness of each layer, for example, the basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer may satisfy the relational expression: 1≤W2/W1≤3. W2/W1 may be 1.2 or more, or may be 1.5 or more. W2/W1 may be 2.8 or less, and may be 2.5 or less. The basis weight refers to mass per unit area.

The basis weight (W1+W2) of the nonwoven fabric is, for example, 25 g/m ² or more and 70 g/m ² or less. When the basis weight of the entire nonwoven fabric is within this range, the liquid absorption rate can be increased without lowering the wetback property. The nonwoven fabric may have a basis weight of 30 g/m ² or more, or may be 32 g/m ² or more. The basis weight of the nonwoven fabric may be 65 g/m ² or less, and may be 60 g/m ² or less.

(contact angle)
It is desirable that the surface water repellency of the first and second fibrous layers do not differ significantly. When the hydrophilicity of the first fibrous layer is excessively greater than that of the second fibrous layer, the highly hydrophilic first fibrous layer takes up a lot of liquid, while the highly water-repellent second fibrous layer absorbs all of this liquid. becomes difficult to pass through. Therefore, the liquid tends to stay between the fiber layers, and the liquid tends to return or leak. On the contrary, when the water repellency of the first fiber layer is excessively high compared to that of the second fiber layer, most of the liquid that can pass through the first fiber layer with high water repellency passes through the second fiber layer with high hydrophilicity. holds. Also in this case, liquid return is likely to occur.

For example, the contact angle θ1 between water and the surface of the first fiber layer and the contact angle θ2 between water and the surface of the second fiber layer may satisfy the relational expression: −40°≦θ1−θ2≦30°. θ1−θ2 may be −38° or more, or −35° or more. θ1−θ2 may be 25° or less, and may be 20° or less.

を用いて、接触角θが求められる。接触角θは、複数（典型的には、５以上）のサンプルにおける平均値である。 The contact angle θ is determined by the θ/2 method. Specifically, the sample (for example, the first fiber layer and the second fiber layer before being integrated) is fixed on the pedestal with a double-sided tape or the like via a film that does not absorb water. A drop of distilled water colored with methylene blue is added to the sample and allowed to stand for 1 minute. Next, the droplet on the sample is photographed from the side with a microscope (eg, 3R-WM401WIFI manufactured by 3R Systems Co., Ltd.). Assuming that the droplet is part of a perfect circle, image analysis determines the length of the line segment (diameter 2r) in contact with the sample of the droplet, and the line passing through the center of the line segment and Find the length (height h) between the line perpendicular to the minute and the outer edge of the droplet. From these values, the following formula:

is used to determine the contact angle θ. The contact angle θ is the average value of multiple (typically 5 or more) samples.

The contact angle is 0° when the distilled water permeates the inside of the sample within 1 minute after the drop of the distilled water.

The contact angle θ of the first fiber layer and the second fiber layer after being integrated is also determined in the same manner as above. At this time, the nonwoven fabric is fixed to the pedestal so that the fiber layer to be measured faces upward.

In addition to the fact that the liquid remaining in the first fiber layer and / or the second fiber layer returns, the liquid absorbed by the ADL returns to the top sheet via the second fiber layer as a cause of the deterioration of the wet back property. Exudation to the surface is mentioned. Therefore, it is desirable that the second fiber layer is thick enough to prevent liquid from seeping out and has an appropriate level of hydrophobicity. Although the reason is not clear, these desirable properties can be expressed by the relationship between the thickness ratio of the second fiber layer in the top sheet and the contact angle θ2 on the surface of the second fiber layer.

を満たしてよい。 From the viewpoint of suppressing the seepage of liquid from the absorber, the contact angle θ2, the thickness T1 of the first fiber layer, and the thickness T2 of the second fiber layer are, for example, the following relational expressions:

may be satisfied.

θ2×T2/(T1+T2) may be 45 or more, or 50 or more. θ2×T2/(T1+T2) may be 83 or less, and may be 80 or less.

を同時に満たすことが望ましい。 Among them, from the viewpoint of the balance between the liquid absorption rate and the wet back property, the following two relational expressions:
-40°≤θ1-θ2≤30°

should be satisfied at the same time.

(thickness)
From the viewpoint of liquid absorption rate, the first fiber layer is preferably thinner than the second fiber layer. For example, the thickness T1 of the first fiber layer and the thickness T2 of the second fiber layer may satisfy the relational expression: T1/T2≦1. T1/T2 may be 0.95 or less, and may be 0.9 or less.

If the second fibrous layer is sufficiently thin (e.g., 550 μm or less) or used in absorbent articles that absorb relatively small amounts of liquid (e.g., less than 30 cc), the above relationship may not be considered. .

The lower limit of T1/T2 is not particularly limited. If the first fiber layer is excessively thin, the texture of the first fiber layer is likely to be affected by the second fiber layer. For example, using thicker, stiffer fibers in the second fibrous layer can reduce the feel of the first fibrous layer. The lower limit of T1/T2 may vary depending on the thickness T1 of the first fiber layer, but may be 0.2, 0.3, or 0.4, for example.

The thicknesses of the first fiber layer and the second fiber layer after being integrated are calculated as follows. First, a cross section cut in the thickness direction of the nonwoven fabric is photographed with a SEM at a magnification of about 50 to 100 times. The magnification is set so that the entire thickness of the nonwoven fabric can be confirmed in the observation field. A cross-section is obtained by cutting the nonwoven fabric on a horizontal table, with the second fibrous layer down, in a direction perpendicular to the table.

The obtained image is imported into image analysis software (for example, ImageJ), and arbitrary five straight lines are drawn parallel to the outer edge of the image in the vertical direction. Among the straight lines, the length of the line segment between the lower surface (surface of the second fiber layer) and the upper surface (surface of the first fiber layer) of the cross section in the image is measured. Let the average value of the length of five line segments be thickness T of the whole nonwoven fabric. Arbitrary straight lines are drawn by selecting portions where the contours of the lower and upper surfaces of the cross section in the image are clear. The length of a line segment is measured by connecting the outermost and clearly visible fibers.

Similarly, the length of the line segment between the upper surface and the boundary of the two fiber layers is measured, and the average value is taken as the thickness T1 of the first fiber layer. The thickness T2 of the second fiber layer is obtained by subtracting the thickness of the first fiber layer T1 from the calculated thickness T of the entire nonwoven fabric. The boundary between the two fiber layers is the point where fibers with different shapes and/or thicknesses appear for the first time by observing fibers on a straight line that is drawn arbitrarily from the upper side to the lower side. and The thickness is the average value of multiple (typically 5 or more) samples.

The thickness T (T1+T2) of the entire nonwoven fabric may be, for example, 350 μm or more, 380 μm or more, or 400 μm or more. When the thickness T is within this range, the wetback property can be further improved. The thickness T may be 1300 μm or less, 1200 μm or less, or 1100 μm or less. When the thickness T is within this range, the liquid absorption speed is likely to increase, and air permeability can also be improved. In one aspect, the thickness T is 350 μm or more and 1300 μm or less.

(irregularities and/or apertures)
The surface of the first fiber layer may have irregularities and/or pores.

Asperities can increase the surface area, which can increase the absorption rate. Also, depending on the method of forming the unevenness, there may be a portion where the degree of entanglement between the first fiber layer and the second fiber layer is high and a portion where the degree is low. In this case, the highly entangled portions can improve the integrity of both fiber layers, and the low entangled portions can improve liquid permeability. In addition, designability is also imparted.

The unevenness may be a pattern applied to the surface of the first fiber layer. Patterns include, for example, mesh, herringbone, stripes, and dots.

The pores allow the liquid to quickly permeate the first fiber layer, so the liquid absorption rate can be increased. Moreover, depending on the formation method, the first fiber layer and the second fiber layer may be formed integrally. In this case, the liquid can quickly permeate both the first and second fiber layers, so the liquid absorption rate can be even faster.

It is desirable that the openings be within a range that does not impair the effects of the first fiber layer (particularly, the wetback property). The porosity is not limited as long as it is greater than 0%. The porosity may be, for example, 5% or more. The porosity may be, for example, 20% or less, or 15% or less. The open area ratio is the ratio of the total area of all the openings in the first fiber layer when the first fiber layer is viewed from its normal direction.

Next, the fibers used will be explained.
The term "hydrophilic" indicates the property of being readily compatible with water. The terms "water-repellent" and "hydrophobic" both indicate the property of not being compatible with water. "Hydrophobicity" is a concept that includes "water repellency". Among them, "water repellency" refers to the property of repelling water.

The water compatibility of the fiber can be evaluated by the sedimentation velocity (6(1) f) measured by the following method, for example, according to the standards for medical gauze and medical absorbent cotton set forth in Notification No. 0630001 of Yakushokuki.

Fibers before the production of nonwoven fabric or fibers collected from the nonwoven fabric are rubbed and washed with warm water (about 40° C.) three times for 2 minutes, and then dried to remove adhering oil and the like. Next, the fibers are defibrated by a carding machine to prepare a fiber assembly. 0.3 g of this fiber aggregate is rolled into a ball with a diameter of 2 cm or less and gently dropped into water of 200 mm depth from a height of 12 mm above the water surface at a water temperature of 24 to 26°C. The settling velocity of the fiber is defined as the time from when the fiber aggregate is dropped until it sinks under the water surface.

If the fibers cannot be defibrated by the carding machine (for example, if the fiber length is short), 0.3 g of the collected fibers may be rolled as they are and dropped into water. Alternatively, if the fibers are already in the form of a fiber assembly (for example, wet-laid nonwoven fabric or air-laid nonwoven fabric) and it is difficult to disentangle this with a carding machine, a piece of nonwoven fabric cut to a size of 1 cm × 1 cm 0 .3 g portions may be dropped into water.

If the settling velocity is less than 1 minute, the fiber is said to be "hydrophilic". The fiber is said to be "hydrophobic" if the sedimentation rate is greater than or equal to 1 minute. Above all, if one drop of water is dropped on a nonwoven fabric made of only one type of fiber, and the shape of the water drop does not change after 10 seconds, the fiber can be evaluated as "water repellent."

(water-repellent cellulose fiber)
Water-repellent cellulose fibers are included as hydrophobic fibers in the first fiber layer. The water-repellent cellulose fiber increases the hydrophobicity of the fiber layer and contributes to the improvement of the wetback property. Since the water-repellent cellulose fiber is flexible and derived from plants, it is suitable for use in the first fiber layer, which is the surface that comes into contact with the skin.

Cellulose fibers are inherently hydrophilic, but in the present disclosure, cellulose fibers artificially imparted with water repellency are referred to as "water-repellent cellulose fibers".

The type of cellulose fiber is not particularly limited. Cellulose fibers include:
(1) Natural fibers derived from plants such as cotton, hemp, linen, ramie, jute, banana, bamboo, kenaf, shell ginger, hemp and kapok;
(2) solvent-spun cellulose fibers such as viscose-derived rayon and polynosic, cuprammonium-derived cupro, and solvent-spun Tencel® and lyocell, and other regenerated fibers;
(3) cellulose fibers obtained by melt spinning;
(4) semi-synthetic fibers such as acetate fibers; and (5) pulps such as mechanical, recycled and chemical pulps.

The water-repellent cellulose fibers may be obtained by attaching a water-repellent agent to these cellulose fibers to impart water repellency. Alternatively, the water-repellent cellulose fibers may be obtained by treating cellulose fibers having carboxyl groups and/or sulfonic acid groups with a treatment liquid containing an isocyanate-based compound and a non-fluorine-based water repellent. A water-repellent cellulose fiber obtained by such a method is disclosed, for example, in JP-A-2019-65443.

The water-repellent cellulose fibers preferably contain water-repellent rayon because the bending resistance of the nonwoven fabric tends to be low. Since rayon has a chrysanthemum-shaped cross-section, it is also preferable in that it tends to exhibit water repellency effectively.

As water-repellent rayon, for example, Eco Repelace (trade name, water-repellent viscose rayon) manufactured by Daiwabo Rayon Co., Ltd., Olea (trade name, water-repellent viscose rayon) manufactured by Kelheim Fibers GmbH, and the like are marketed. In particular, Eco Repellent (trade name) exhibits high water repellency, has highly durable water repellency, and is preferably used because the water repellency does not easily decrease even when subjected to, for example, hydroentanglement treatment.

The fineness of the water-repellent cellulose fibers may be 0.6 dtex or more, 1.0 dtex or more, or 1.4 dtex or more. The fineness of the water-repellent cellulose fibers may be 6.0 dtex or less, 5.0 dtex or less, or 3.0 dtex or less. In one aspect, the water-repellent cellulose fiber has a fineness of 0.6 dtex or more and 6.0 dtex or less. When the fineness of the water-repellent cellulose fibers is within the above range, appropriate voids are formed in the first fiber layer, and the liquid absorption rate tends to increase. The fineness of the water-repellent cellulose fiber is not limited to the above range. In particular, since it is difficult to adjust the fineness of natural fibers, cellulose fibers having a fineness outside the above range may be used. In general, pulp has a fineness of about 1.0 dtex or more and 4.0 dtex or less, and a fiber length of about 0.8 mm or more and 4.5 mm or less.

The fiber length of the water-repellent cellulose fiber is not particularly limited, and may be appropriately selected according to the material, the manufacturing method thereof, the method of manufacturing the fiber layer, the manufacturing method of the nonwoven fabric, and the like. Water-repellent cellulose fibers are, for example, staple fibers. When the fibrous layer is made from a carded web, the fiber length of the water-repellent cellulose fibers may be 100 mm or less, 75 mm or less, or 65 mm or less. The fiber length of the short water-repellent cellulose fibers may be 10 mm or more, 20 mm or more, or 30 mm or more. In the above case, in one aspect, the fiber length of the water-repellent cellulose fiber may be 10 mm or more and 100 mm or less. When the fiber layer is made from an air-laid web, the fiber length of the water-repellent cellulose fibers may be 2 mm or more and 20 mm or less.

In this embodiment, a plurality of water-repellent cellulose fibers having one or more different materials, fiber lengths, and finenesses may be used.

The sedimentation rate of the water-repellent cellulose fibers is 1 minute or more, preferably 5 minutes or more, and particularly preferably 10 minutes or more. In particular, it is preferable that at least a part of the water-repellent cellulose fibers does not settle under the water surface 10 minutes after the water-repellent cellulose fibers are dropped into the water. At this time, the water-repellent cellulose fibers may absorb water. In particular, it is preferable that part or all of the water-repellent cellulose fibers float on the water surface after 1 minute.

Water-repellent cellulose fibers have water repellency like ordinary hydrophobic synthetic fibers, but this water repellency is exhibited on the fiber surface. The inside of the water-repellent cellulose fibers still has the function of absorbing and retaining water. Therefore, the official moisture content of water-repellent cellulose fibers (especially water-repellent rayon) is equivalent to that of the same kind of cellulose fibers that have not been water-repellent treated. The degree of secondary swelling of water-repellent cellulose fibers is inferior to that of non-water-repellent cellulose fibers, but tends to be higher than that of general synthetic fibers. For example, viscose rayon not treated with water repellent treatment has a secondary swelling degree (water swelling degree: measured according to JIS L1015: 2010 8.26) of about 80% or more and 90% or less. Some have a degree of secondary swelling of about 45% to 55%. Further, there is a water-repellent rayon having an official moisture content (measured according to JIS L 1015) of about 10% to 13%. The official moisture content of this water-repellent rayon is equivalent to the official moisture content (11%) of general rayon that has not been water-repellent treated.

(hydrophilic fiber)
Hydrophilic fibers are fibers with a sedimentation velocity of less than 1 minute as measured by the method described above. Hydrophilic fibers increase the hydrophilicity of the fiber layer and contribute to the improvement of liquid absorption rate. Hydrophilic fibers include, for example, hydrophilic cellulose fibers, animal natural fibers (silk, wool, etc.), hydrophilic synthetic fibers, and hydrophilic synthetic fibers.

The settling rate of the hydrophilic fibers is less than 1 minute, may be within 50 seconds, may be within 45 seconds, may be within 30 seconds.

<Hydrophilic cellulose fiber>
The term "hydrophilic cellulosic fibers" is used to distinguish from water-repellent cellulosic fibers and refers to cellulosic fibers that have not been imparted with water repellency and that have inherent hydrophilic properties. Examples of hydrophilic cellulose fibers, fineness and fiber length are as described for water-repellent cellulose fibers.

Hydrophilic cellulosic fibers may be natural fibres, pulp, regenerated fibres, or semi-synthetic fibres. Pulp is produced in a conventional manner, for example, from softwood or hardwood. Pulp includes, for example, mechanical pulp, recycled pulp and chemical pulp. The hydrophilic cellulose fibers with a fiber length of less than 10 mm may be pulp or cut regenerated or semi-synthetic fibers. From a softness point of view, the hydrophilic cellulose fibers may contain regenerated fibers, especially rayon.

<Hydrophilic Synthetic Fiber>
A hydrophilic synthetic fiber is a synthetic fiber having a sedimentation velocity of less than 1 minute as measured by the method described above. Hydrophilic synthetic fibers have hydroxyl groups derived from raw materials, or have inherent hydrophilicity, and generally have an official moisture content of 2% or more. Examples of hydrophilic synthetic fibers include aramid fibers, vinylon fibers, nylon fibers, and acrylic fibers. Details of the synthetic fiber will be described later.

<Hydrophilized Synthetic Fiber>
A hydrophilized synthetic fiber is also a synthetic fiber having a settling velocity of less than 1 minute as measured by the method described above. However, the hydrophilic synthetic fibers are obtained by hydrophilizing the above hydrophilic synthetic fibers and other synthetic fibers (hereinafter sometimes referred to as "hydrophobic synthetic fibers"). Hydrophilization treatments include, for example, corona discharge treatment, sulfonation treatment, graft polymerization treatment, kneading of a hydrophilic agent into fibers, and application of a durable oil.

<<Hydrophilic fibers contained in the first fiber layer>>
The hydrophilic fibers contained in the first fiber layer (hereinafter referred to as first hydrophilic fibers) are not particularly limited. The first hydrophilic fibers may comprise hydrophilic cellulosic fibers. Hydrophilic cellulose fibers are plant-derived, and are therefore particularly suitable for use in the first fiber layer, which is the skin-contacting surface. Furthermore, from the viewpoint of SDGs, it may be a hydrophilic cellulose fiber.

The fineness of the first hydrophilic fiber is appropriately selected according to the fineness of other fibers to be mixed. The fineness of the first hydrophilic fibers may be similar to that of the water-repellent cellulose fibers. The fineness of the first hydrophilic fibers may be 0.3 dtex or more, 0.5 dtex or more, 1.0 dtex or more, or 1.4 dtex or more. The fineness of the first hydrophilic fibers may be 6.0 dtex or less, 5.0 dtex or less, or 3.0 dtex or less. In one aspect, the fineness of the first hydrophilic fibers is 0.3 dtex or more and 6 dtex or less. When the fineness of the first hydrophilic fibers is within this range, the liquid absorption rate tends to increase.

In one aspect, the fineness of the first hydrophilic fibers is 0.5 dtex or more and 3 dtex or less. When the fineness of the first hydrophilic fibers is within this range, even when a relatively large amount of liquid (for example, 30 cc or more) is applied, a sufficient liquid absorption rate is likely to be obtained. The fineness of the first hydrophilic fibers may be 1.0 dtex or more, and may be 1.4 dtex or more. The fineness of the first hydrophilic fibers may be 2.5 dtex or less, and may be 2.0 dtex or less.

The fiber length of the first hydrophilic fibers is not particularly limited, and is appropriately selected according to the material, the manufacturing method thereof, the manufacturing method of the first fiber layer, the manufacturing method of the nonwoven fabric, etc., as described above. The fiber length of the first hydrophilic fibers may be the same as that of the water-repellent cellulose fibers.

The first fiber layer may contain multiple types of hydrophilic fibers that differ in one or more of material, fiber length, and fineness. The classification of fiber materials is based on, for example, the "terms indicating the name of fibers" published by the Consumer Affairs Agency (https://www.caa.go.jp/policies/policy/representation/household_goods/guide/fiber/fiber_term .html) in accordance with "Types of fibers, etc."

<<Hydrophilic fibers contained in the second fiber layer>>
The hydrophilic fibers contained in the second fiber layer (hereinafter referred to as second hydrophilic fibers) are not particularly limited. The second fiber layer may contain, as hydrophilic fibers, at least one selected from the group consisting of hydrophilic cellulose fibers, hydrophilic synthetic fibers and hydrophilic synthetic fibers. Details of each fiber are as described above. In addition, 2nd Embodiment prescribe|regulates the aspect which a 2nd fiber layer contains a hydrophilic cellulose fiber, a hydrophilized synthetic fiber, or a hydrophilic synthetic fiber as a hydrophilic fiber.

The fineness of the second hydrophilic fiber is appropriately selected according to the fineness of other fibers to be mixed. The fineness of the second hydrophilic fibers may be similar to that of the hydrophobic fibers. The fineness of the second hydrophilic fibers is, for example, 1.0 dtex or more, may be 1.5 dtex or more, or may be 2.0 dtex or more. The fineness of the second hydrophilic fibers is, for example, 6.0 dtex or less, may be 5.0 dtex or less, or may be 4.0 dtex or less. When the fineness of the second hydrophilic fiber is within this range, the liquid permeability is likely to be improved, and the strength is likely to be ensured. In addition, the second fiber layer tends to be uniform.

The fiber length of the second hydrophilic fibers is not particularly limited, and is appropriately selected according to the material, the manufacturing method thereof, the manufacturing method of the second fiber layer, the manufacturing method of the nonwoven fabric, etc., as described above. When the second fibrous layer is made from a carded web, the fiber length of the second hydrophilic fibers may be 100 mm or less, 75 mm or less, or 65 mm or less. In this case, the fiber length of the second hydrophilic fibers may be 10 mm or longer, 20 mm or longer, or 30 mm or longer. In the above case, in one aspect, the fiber length of the second hydrophilic fibers may be 10 mm or more and 100 mm or less. When the second fiber layer is made from an airlaid web, the fiber length of the second hydrophilic fibers may be 2 mm or more and 20 mm or less.

The second fiber layer may contain multiple types of hydrophilic fibers that differ in one or more of material, fiber length, and fineness.

(hydrophobic fiber)
Hydrophobic fibers increase the hydrophobicity of the fiber layer and contribute to the improvement of wetback properties. Hydrophobic fibers include, for example, water-repellent cellulosic fibers and hydrophobic synthetic fibers.

The sedimentation rate of the hydrophobic synthetic fiber is 1 minute or more, preferably 5 minutes or more, and particularly preferably 10 minutes or more.

Details of the water-repellent cellulose fibers are as described above.

<Synthetic fiber>
The hydrophilicity and official moisture content of synthetic fibers mainly depend on their raw materials.
Raw materials for synthetic fibers are generally thermoplastic resins. The thermoplastic resin is not particularly limited. (including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, propylene copolymers containing propylene as the main component (propylene-ethylene copolymers, propylene-butene-1-ethylene copolymers including), ethylene-vinyl alcohol copolymer, and ethylene-polyolefin resins such as vinyl acetate copolymers; polyamide resins such as nylon 6, nylon 12 and nylon 66; acrylic resins; polyurethane resins; , engineering plastics such as polyacetal, polystyrene, polyphenylene sulfide and cyclic polyolefin, and elastomers thereof.

Synthetic fibers may be single fibers made up of a single component (also referred to as "single section") and/or composite fibers made up of multiple components (also referred to as "sections"). The conjugate fiber may be, for example, a concentric or eccentric core-sheath conjugate fiber, a sea-island conjugate fiber, a side-by-side conjugate fiber, or a split conjugate fiber. The cross-section of the fibers may be circular or non-circular. Non-circular shapes include oval, Y-shaped, X-shaped, I-shaped, multi-lobed, polygonal, star-shaped, and the like. The synthetic fiber may have a hollow cross-section in that the bulkiness of the nonwoven fabric is likely to be improved and the internal voids are likely to be large.

In both the single fiber and the composite fiber, each section constituting the fiber may consist of one type of resin, or may be a mixture of two or more types of resin.

In bicomponent fibers, two or more components may be arranged such that the thermoplastic with the lowest melting point constitutes a portion of the fiber surface. In that case, in the process of producing a non-woven fabric, when heat is applied under conditions where a component made of a thermoplastic resin with the lowest melting point (hereinafter referred to as "low melting point component") melts or softens, the low melting point component becomes an adhesive component. Such synthetic fibers can function as adhesive fibers.

A combination of resins (first/second) constituting a conjugate fiber composed of a first component that is a thermoplastic resin with a higher melting point and a second component that is a thermoplastic resin with a lower melting point is, for example, polyethylene terephthalate /Polyethylene, polyethylene terephthalate/polypropylene, and polyethylene terephthalate/propylene copolymers, and combinations of polyester resins and polyolefin resins, and two types of polyolefins, such as polypropylene/polyethylene and polypropylene/propylene copolymers. A combination of plastic resins and a combination of two types of polyester resins having different melting points.

Alternatively, the combination of the first component and the second component may be a combination of biodegradable resins, and such a combination can increase the proportion of biodegradable fibers in the nonwoven fabric. Specifically, by using polylactic acid as the first component and polybutylene succinate as the second component, the adhesive fiber can be made biodegradable.

Alternatively, the combination of the first component and the second component may be a thermoplastic resin using a plant-derived raw material (biomass raw material). According to this combination, the ratio of the biomass raw material in the nonwoven fabric can be increased. Specific resin combinations include biopolyester/biopolyethylene, biopolyester/biopolypropylene, biopolypropylene/biopolyethylene, and polylactic acid/polybutylene succinate as the first component.

The number of divisions of the splittable conjugate fiber (that is, the number of sections in the conjugate fiber) may be, for example, 4 or more and 32 or less, particularly 4 or more and 20 or less, and more particularly 6 or more and 10 or less. can be The fineness of the splittable conjugate fiber after splitting may be, for example, 0.1 dtex or more and 1.0 dtex.

<<Hydrophobic fibers contained in the first fiber layer>>
The hydrophobic fibers contained in the first fiber layer are, as described above, water-repellent cellulose fibers. The first fiber layer may contain a plurality of types of hydrophobic fibers that differ in one or more of material, fiber length and fineness.

<<Hydrophobic fibers contained in the second fiber layer>>
The hydrophobic fibers that can be included in the second fiber layer (hereinafter referred to as second hydrophobic fibers) are not particularly limited. The second hydrophobic fibers may comprise at least one of water-repellent cellulosic fibers and hydrophobic synthetic fibers. From the viewpoint of ensuring strength, the second hydrophobic fibers may contain hydrophobic synthetic fibers.

The fineness of the second hydrophobic fiber is appropriately selected according to the fineness of other fibers to be mixed. The fineness of the second hydrophobic fibers may be similar to that of the second hydrophilic fibers. The fineness of the second hydrophobic fibers is, for example, 1.0 dtex or more, may be 1.5 dtex or more, or may be 2.0 dtex or more. The fineness of the second hydrophilic fibers is, for example, 6.0 dtex or less, may be 5.0 dtex or less, or may be 4.0 dtex or less.

The fiber length of the second hydrophobic fiber is not particularly limited, and is appropriately selected according to the material, the manufacturing method thereof, the method of manufacturing the second fiber layer, the manufacturing method of the nonwoven fabric, etc., as described above. The fiber length of the second hydrophobic fibers may be the same as that of the second hydrophilic fibers.

The second fiber layer may contain multiple types of hydrophobic fibers that differ in one or more of material, fiber length, and fineness.

<Adhesive fiber>
Each fibrous layer (typically the second fibrous layer) may contain adhesive fibers. Adhesive fibers bond fibers together. As a result, the strength of the laminated nonwoven fabric is improved and excessive elongation is suppressed.

Adhesive fibers are, for example, the synthetic fibers mentioned above. Adhesive fibers may be synthetic fibers contained in the fiber layer in an adhesive state. In this case, the synthetic fibers may be hydrophobic or hydrophilic, and may be hydrophilized. The fineness and fiber length of the adhesive fibers may be comparable to those of synthetic fibers.

(I) First Embodiment A nonwoven fabric for absorbent articles according to a first embodiment (hereinafter referred to as nonwoven fabric A) comprises a first fiber layer and second fibers located on one main surface of the first fiber layer. a layer; The first fiber layer and the second fiber layer are integrated by entangling the fibers. The first fiber layer contains more than 30% by mass and 90% by mass or less of water-repellent cellulose fibers and 10% by mass or more of hydrophilic fibers based on the total mass of the first fiber layer. The second fiber layer contains 5% by mass or more of hydrophilic fibers based on the total mass of the second fiber layer. Both the contact angle θ1 between water and the surface of the first fiber layer and the contact angle θ2 between water and the surface of the second fiber layer before water permeation are 75° or more.

Both the first and second fibrous layers contain a certain amount of hydrophilic fibers. Therefore, each fiber layer has moderate hydrophilicity, and liquid can easily permeate through it. Therefore, the liquid absorption speed is increased.

Since both the first and second fiber layers have a contact angle of 75° or more, the liquid quickly reaches the ADL without staying in each layer. In addition, the liquid absorbed by the ADL is quickly dispersed and migrates to the absorbent layer, and is hindered by the high water repellency of the first and second fiber layers, making it difficult for it to seep out onto the surface of the top sheet. These actions improve the wetback property. If the contact angles .theta.1 and .theta.2 are less than 75.degree., the hydrophilicity is excessively high, and the liquid tends to remain in the layer without being permeated. Therefore, the wetback property is deteriorated.

A contact angle θ of at least one of the first and second fiber layers may be 80° or more, 85° or more, 88° or more, or 90° or more. The contact angle θ of at least one of the first and second fiber layers may be 120° or less, 119° or less, or 118° or less. When the contact angle θ1 of the first fiber layer is 120° or less, the liquid absorption speed can be increased. When the contact angle θ2 of the second fiber layer is 120° or less, it becomes easier to suppress the retention of liquid between the first and second fiber layers.

In one aspect, both the contact angles θ of the first and second fiber layers are 75° or more and 120° or less. The contact angle between the surfaces of the first and second fiber layers and water is 75° or more and 120° or less (hereinafter sometimes referred to as weak water repellency), so that liquid permeability and liquid return The balance with the suppressing ability is improved, and it becomes easier to achieve both a high liquid absorption rate and excellent wet back properties.

(First fiber layer A)
The first fiber layer (hereinafter referred to as first fiber layer A) in the first embodiment is a contact surface with the skin. The first fiber layer A contains water-repellent cellulose fibers. The water-repellent cellulose fiber is contained in the first fibrous layer A in an amount of more than 30% by mass and not more than 90% by mass based on the total mass of the fibrous layer. If the content of the water-repellent cellulose fiber is 30% by mass or less, the wetback property tends to deteriorate. If the water-repellent cellulose fiber content exceeds 90% by mass, the liquid absorption speed tends to be slow. The content of water-repellent cellulose fibers may be 40% by mass or more, or may be 50% by mass or more. The content of water-repellent cellulose fibers may be 85% by mass or less, and may be 80% by mass or less.

The hydrophilic fiber is contained in the first fiber layer A in an amount of 10% by mass or more based on the total mass of each fiber layer. If the content of the hydrophilic fibers is less than 10% by mass, the water repellency of the first fiber layer A becomes too high, the liquid absorption rate becomes low, and liquid leakage may occur. The content of hydrophilic fibers may be 15% by mass or more, or may be 20% by mass or more. The content of hydrophilic fibers is, for example, less than 70% by mass, may be 60% by mass or less, or may be 50% by mass or less. In one aspect, the content of hydrophilic fibers is 10% by mass or more and less than 70% by mass. The type of hydrophilic fibers contained in the first fiber layer A is not particularly limited. From the viewpoint of appealing power to users, it may be a hydrophilic cellulose fiber.

The first fibrous layer A may contain fibers other than water-repellent cellulose fibers and hydrophilic fibers. Other fibers include, for example, hydrophobic synthetic fibers and adhesive fibers.

The mass ratio of other fibers may be 30% by mass or less, 20% by mass or less, 10% by mass or less, or 8% by mass or less, based on the total mass of the fiber layer. and may be 5% by mass or less. From the viewpoint of wetback property and liquid absorption speed, the first fiber layer A may be composed only of water-repellent cellulose fibers and hydrophilic fibers. In particular, from the viewpoint of appealing power to users, the first fiber layer A may be composed of only two types of water-repellent cellulose fibers and hydrophilic cellulose fibers.

The content ratio of each fiber described above is the ratio of the fibers contained in the first fiber layer A before being integrated with other layers. For example, even if some of the fibers constituting the second fiber layer are mixed in the first fiber layer A in the nonwoven fabric, the mixed fibers are not included in the first fiber layer A. The same applies to the second fiber layer A, the first fiber layer B, and the second fiber layer B, which will be described later.

The basis weight W1 of the first fiber layer A is not particularly limited. The basis weight W1 may be 10 g/m ² or more, 12.5 g/m ² or more, or 15 g/m ² or more. When the basis weight W1 is within this range, the fibers of the first and second fiber layers are likely to be entangled. The basis weight W1 may be 35 g/m ² or less, 32.5 g/m ² or less, or 30 g/m ² or less. When the basis weight W1 is within this range, the liquid absorption rate tends to increase. In one aspect, the basis weight W1 is 10 g/m ² or more and 35 g/m ² or less.

The thickness T1 of the first fiber layer A is not particularly limited. The thickness T1 may be 120 μm or more, 130 μm or more, or 150 μm or more. When the thickness T1 is within this range, the wetback property can be further improved. The thickness T1 may be 500 μm or less, 450 μm or less, or 400 μm or less. When the thickness T1 is within this range, the liquid absorption rate tends to increase. In one aspect, the thickness T1 is 120 μm or more and 500 μm or less.

(Second fiber layer A)
The second fiber layer (hereinafter referred to as the second fiber layer A) in the first embodiment has the role of rapidly allowing liquid to permeate the ADL and suppressing liquid return from the ADL, and has a wet-back property. Contribute to improvement. Furthermore, the second fiber layer A ensures the strength of the top sheet.

The second fiber layer A contains 5% by mass or more of hydrophilic fibers based on the total mass of the second fiber layer A. As a result, moderate hydrophilicity is imparted to increase the liquid absorption rate. If the hydrophilic fiber content is less than 5% by mass, the liquid that permeates the first fiber layer A tends to stay between the layers, which may cause liquid leakage. From the viewpoint of wet back properties, the content of hydrophilic fibers may be 90% by mass or less. The content ratio of the hydrophilic fibers in the second fiber layer A is appropriately set according to the type.

Other configurations of the second fiber layer A are not particularly limited as long as the contact angle θ2 is 75° or more. The second fibrous layer A may contain hydrophobic fibers along with hydrophilic fibers. The configuration of the second fiber layer A may be the same as that of the second fiber layer B in the second embodiment described later.

(II) Second Embodiment A nonwoven fabric for absorbent articles according to a second embodiment (hereinafter referred to as nonwoven fabric B) comprises a first fiber layer and second fibers located on one main surface of the first fiber layer. a layer; The first fiber layer and the second fiber layer are integrated by entangling the fibers. The first fiber layer contains more than 30% by mass and 90% by mass or less of water-repellent cellulose fibers and 10% by mass or more and less than 70% by mass of hydrophilic fibers based on the total mass of the first fiber layer. The second fiber layer contains hydrophobic fibers and (a) hydrophilic cellulose fibers in an amount of 5% by mass or more and 40% by mass or less based on the total mass of the second fiber layer, and (b) hydrophilized synthetic fibers, 40% by mass or more and 90% by mass or less based on the total mass of the second fiber layer, or (c) 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fiber layer .

By using (a), (b) or (c) above for the fibers constituting the second fiber layer, the surface can be given appropriate water repellency. Therefore, the wetback property of the nonwoven fabric B is improved.

The contact angle θ of at least one of the first and second fiber layers may be 75° or more, 80° or more, 85° or more, 88° or more, or 90°. or more. The contact angle θ of at least one of the first and second fiber layers may be 120° or less, 119° or less, or 118° or less.

In one aspect, both the contact angles θ of the first and second fiber layers are 75° or more and 120° or less. Since the surfaces of the first and second fiber layers are weakly water-repellent, the balance between liquid permeability and liquid backflow suppression is improved, making it easier to achieve both excellent liquid absorption speed and excellent wetback property. become.

(First fiber layer)
The first fiber layer (hereinafter referred to as the first fiber layer B) in the second embodiment is the contact surface with the skin. The first fibrous layer B contains a specific proportion of water-repellent cellulose fibers and hydrophilic fibers. Therefore, the first fiber layer B has both moderate water repellency and hydrophilicity. In addition, the inclusion of cellulose fibers in the first fiber layer that contacts the skin gives the user a sense of security and an impression of safety, and can be highly appealing.

The water-repellent cellulose fiber is contained in the first fiber layer B in an amount of more than 30% by mass and not more than 90% by mass based on the total mass of the fiber layer. Examples of the content ratio of the water-repellent cellulose fibers contained in the first fiber layer B include the same ranges as those for the water-repellent cellulose fibers contained in the first fiber layer A.

The first fiber layer B contains hydrophilic fibers. The hydrophilic fiber is contained in the first fiber layer B in an amount of 10% by mass or more and less than 70% by mass based on the total mass of the fiber layer. If the hydrophilic fiber content is 10% by mass or less, the liquid absorption rate tends to decrease, and liquid leakage may occur. If the hydrophilic fiber content exceeds 70% by mass, the wetback property is likely to deteriorate. The content of hydrophilic fibers may be 15% by mass or more, or may be 20% by mass or more. The content of hydrophilic fibers may be 60% by mass or less and may be 50% by mass or more.

The first fibrous layer B may contain fibers other than water-repellent cellulose fibers and hydrophilic fibers. Examples of other fiber types and mass ratios include ranges similar to those of the other fibers contained in the first fiber layer A. From the viewpoint of wetback property and liquid absorption rate, the first fiber layer B may be composed only of water-repellent cellulose fibers and hydrophilic fibers.

The basis weight and thickness of the first fiber layer B may be the same as the basis weight W1 and thickness T1 of the first fiber layer A.

(Second fiber layer B)
The role of the second fiber layer (hereinafter referred to as the second fiber layer B) in the second embodiment is the same as that of the second fiber layer A. The second fiber layer B contains hydrophobic fibers and hydrophilic fibers. As a result, the second fiber layer B is imparted with appropriate hydrophilicity and water repellency.

Hydrophobic fibers typically include hydrophobic synthetic fibers and water-repellent cellulose fibers. From the viewpoint of ensuring strength, the hydrophobic fibers may include hydrophobic synthetic fibers. The content ratio of the hydrophobic fibers is appropriately set according to the type and content ratio of the hydrophilic fibers.

Hydrophilic fibers include hydrophilic cellulosic fibers, hydrophilized synthetic fibers and hydrophilic synthetic fibers. Hydrophilic cellulose fibers, hydrophilized synthetic fibers and hydrophilic synthetic fibers can all be collectively referred to as hydrophilic fibers, but their properties are different. As described above, the second fiber layer is required to have a high liquid absorbency that allows the liquid to quickly transfer to the ADL, as well as an excellent wetback property. Therefore, it is desirable that a moderate amount of liquid is retained inside the second fiber layer. The content ratio of the various hydrophilic fibers described above is determined in consideration of their properties and the balance between liquid absorbency and liquid retention.

(a) When Hydrophilic Cellulose Fiber is Contained Hydrophilic cellulose fiber has high hydrophilicity, so that it is excellent in liquid absorption and easily retains liquid excessively. Therefore, when the second fibrous layer B contains hydrophilic cellulose fibers, the content ratio thereof is set to 5% by mass or more and 40% by mass or less based on the total mass of the second fibrous layer B. Thereby, the second fiber layer B can exhibit moderate water repellency (for example, a contact angle of 75° or more), and excessive liquid retention inside the second fiber layer B is suppressed.

The content of hydrophilic cellulose fibers may be 8% by mass or more, 10% by mass or more, or 15% by mass or more. The content of hydrophilic cellulose fibers may be 35% by mass or less, 30% by mass or less, or 25% by mass or less.

(b) When Hydrophilized Synthetic Fiber is Included Hydrophilized synthetic fiber is obtained by subjecting hydrophobic synthetic fiber to hydrophilization treatment. Therefore, although it has a liquid retention property, its degree is not higher than that of hydrophilic cellulose fiber. Therefore, the hydrophilic synthetic fibers can be contained in the second fiber layer B in a larger amount than the hydrophilic cellulose fibers. When the second fiber layer B contains hydrophilic synthetic fibers, the content is 40% by mass or more and 90% by mass or less based on the total mass of the second fiber layer B. Thereby, the second fiber layer B can exhibit moderate water repellency (for example, a contact angle of 75° or more), and the second fiber layer B exhibits moderate liquid retention.

The content of the hydrophilic synthetic fiber may be 43% by mass or more, 45% by mass or more, or 48% by mass or more. The content of the hydrophilic synthetic fiber may be 85% by mass or less, 80% by mass or less, or 75% by mass or less.

(c) When Hydrophilic Synthetic Fiber is Contained Hydrophilic synthetic fiber has a lower swelling property and a lower liquid absorption and retention property than hydrophilic cellulose. On the other hand, hydrophilic synthetic fibers can have higher liquid retention than hydrophilic synthetic fibers. Therefore, when the second fiber layer B contains hydrophilic synthetic fibers, the content ratio thereof is 30% by mass or more and 90% by mass or less based on the total mass of the second fiber layer B. Thereby, the second fiber layer B can exhibit moderate water repellency (for example, a contact angle of 75° or more), and the second fiber layer B exhibits moderate liquid retention.

The content of hydrophilic synthetic fibers may be 35% by mass or more, 40% by mass or more, or 50% by mass or more. The content of hydrophilic synthetic fibers may be 85% by mass or less, 80% by mass or less, or 75% by mass or less.

The second fiber layer B may further contain adhesive fibers from the viewpoint of strength. Adhesive fibers are classified into hydrophilic fibers and hydrophobic fibers depending on the degree of hydrophilicity. The mass ratio of the adhesive fibers may be 50% by mass or less, 45% by mass or less, or 40% by mass or less based on the total mass of the second fiber layer B. The mass ratio of the adhesive fibers may be 10% by mass or more, 15% by mass or more, or 20% by mass or more based on the total mass of the second fiber layer B.

The basis weight W2 of the second fiber layer B is not particularly limited. The basis weight W2 may be 10 g/m ² or more, 12.5 g/m ² or more, or 15 g/m ² or more. When the basis weight W2 is within this range, the fibers of the first and second fiber layers are likely to be entangled. The basis weight W2 may be 35 g/m ² or less, 32.5 g/m ² or less, or 30 g/m ² or less. When the basis weight W2 is within this range, the liquid absorption rate tends to be faster. In one aspect, the basis weight W2 is 10 g/m ² or more and 35 g/m ² or less. The basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer may satisfy the relational expression: 1≦W2/W1≦3.

The thickness T2 of the second fiber layer B is not particularly limited. The thickness T2 may be greater than or equal to 200 μm, greater than or equal to 210 μm, or greater than or equal to 220 μm. When the thickness T2 is within this range, the wetback property can be further improved. The thickness T2 may be 800 μm or less, may be 780 μm or less, or may be 770 μm or less. When the thickness T2 is within this range, the liquid absorption rate tends to increase. In one aspect, the thickness T2 is 200 μm or more and 800 μm or less. The thickness T1 of the first fiber layer and the thickness T2 of the second fiber layer may satisfy the relational expression: 1≤T2/T1≤3.

[Absorbent article]
Absorbent articles according to the present disclosure include nonwoven fabrics according to the present disclosure.
In the absorbent article, the nonwoven fabric according to the present disclosure is arranged, for example, so that the first fiber layer is the skin-contacting surface. In other words, the nonwoven fabric according to the present disclosure is used as a topsheet of an absorbent article, with the first fibrous layer positioned on the side closer to the user's skin.

Absorbent articles, for example, comprise a nonwoven fabric (topsheet) according to the present disclosure, a backsheet, an absorbent dispersion (ADL) disposed between the topsheet and the backsheet, and an absorbent body. The backsheet is liquid impermeable. The configuration of ADL is not particularly limited. The ADL is composed of, for example, an airlaid, spunlaced, air-through nonwoven, or foam material containing hydrophilic or hydrophobic synthetic fibers. The absorbent has the role of absorbing and retaining the liquid component that has permeated the topsheet and ADL. As the absorber, for example, pulp or high-molecular-weight absorbent polymer (also called SAP) is used.

The use of the absorbent article is not particularly limited. The absorbent article may be one that absorbs small amounts of highly viscous liquids, such as menses, or one that absorbs large amounts of low-viscosity liquids, such as urine. According to the nonwoven fabric of the present disclosure, excellent liquid absorption speed and excellent wet back properties are exhibited regardless of the viscosity and amount of the liquid to be absorbed.

Specific examples of absorbent articles include diapers, incontinence pads, napkins, and panty liners.

[Method for producing nonwoven fabric for absorbent articles]
The nonwoven fabric according to the present embodiment is produced, for example, by producing a first fibrous web forming the first fibrous layer and a second fibrous web forming the second fibrous layer, and laminating these to produce a laminated fibrous web. and subjecting the laminated fibrous web to an entangling treatment using a high pressure fluid stream to entangle the fibers.

(1) Production of Laminated Fiber Web First, a first fiber web and a second fiber web are prepared.
Each fiber web, as described above, may be a precursor of a nonwoven fabric produced by a carded method, an airlaid method, a wet method, or the like, and may be a nonwoven fabric produced by a spunlace method, a spunbond method, a wet method, or the like. you can Above all, from the viewpoint of flexibility, each fibrous web may be a nonwoven precursor or a nonwoven fabric produced by a carded method, an airlaid method, a wet method, or the like.

The types and proportions of fibers contained in the first fiber web and the second fiber web are as described above in relation to the first fiber layer and the second fiber layer. The basis weight is as described above in relation to the first fiber layer and the second fiber layer.

A first fibrous web and a second fibrous web are superimposed to form a laminated fibrous web.

(2) Entanglement Treatment The laminated fiber web is subjected to an entanglement treatment using a high-pressure fluid stream to entangle the fibers. As a result, a nonwoven fabric is obtained in which the first fiber layer and the second fiber layer are integrated by entangling the fibers.

High-pressure fluids are, for example, high-pressure gases such as compressed air and high-pressure liquids such as high-pressure water. Hereinafter, the method for producing a nonwoven fabric according to the present disclosure will be described by taking as an example the case where high-pressure water (hereinafter also simply referred to as “water flow”) is used as the high-pressure fluid, but the method is not limited to this.

The hydroentangling treatment is carried out by placing the laminated fibrous web on a support and jetting a columnar stream of water. The support is, for example, a plain weave of 80 mesh or more and 100 mesh or less. The water stream is jetted from a nozzle in which orifices having 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, for example. The water pressure is, for example, 1 MPa or more and 15 MPa or less. The water pressure may be 10 MPa or less, and may be 7 MPa or less. The water stream is jetted 1 to 5 times on each of the front and back surfaces of the laminated fibrous web.

(3) Formation of unevenness and/or openings After the entangling treatment, unevennesses and/or openings may be formed on the first fiber web side of the laminated fiber web. As a result, a nonwoven fabric having a first fiber layer with unevenness and/or pores on the surface is obtained.

Concavities and convexities are formed, for example, by performing a hydroentanglement treatment using a support on which one or more selected from convex portions, concave portions and openings are regularly arranged. Alternatively, the irregularities are 1) nozzles in which fine orifices from which high-pressure fluid is ejected are arranged at intervals of, for example, several mm, or 2) fine orifices from which high-pressure fluid is ejected are arranged at intervals. It is formed by performing a hydroentangling process using nozzles in which orifice assembly portions and orifice-free portions are alternately arranged.

The material and shape of the support, the spacing and shape of the orifices, and the like are appropriately set according to desired unevenness and/or openings. The water pressure may be the same as in (2) the entanglement treatment.

(4) Bonding Treatment When at least one of the first fibrous web and the second fibrous web (typically, the second fibrous web) contains adhesive fibers, the laminated fibrous web is subjected to bonding treatment. As a result, some of the fibers are bonded to each other, and the mechanical strength of the nonwoven fabric can be improved. The adhesion treatment may be thermal adhesion treatment, adhesion by electron beam irradiation, or ultrasonic welding. According to the heat treatment, the adhesive fibers (for example, the low-melting-point component of the composite fiber) are melted or softened by heating during the heat treatment, and the fibers are adhered to each other. Adhesion treatment is usually performed after entanglement treatment.

The heat treatment is, for example, hot air processing (also referred to as air-through processing) in which hot air is blown, hot roll processing (hot embossing roll processing), or heat treatment using infrared rays. The heat treatment temperature (for example, the temperature of hot air) may be a temperature at which the component that constitutes the adhesive fiber and functions as an adhesive component softens or melts. For example, the heat treatment temperature may be a temperature above the melting point of the component. For example, when the adhesive fiber contains polyethylene as a component and polyethylene is used as the adhesive component, the heat treatment temperature may be 130 ° C. to 150 ° C., and when polybutylene succinate is used as the adhesive component, the heat treatment temperature is 120. °C to 133 °C.

The present disclosure will now be described with reference to examples.
The following fibers were prepared as fibers used in this example.

[Hydrophilic fiber]
(hydrophilic cellulose fiber)
0.6T rayon: fineness 0.6 dtex, fiber length 32 mm, viscose rayon, product name: BH, manufactured by Daiwabo Rayon Co., Ltd., sedimentation rate of about 3.5 seconds, official moisture content of 11%
1.7T rayon: fineness 1.7 dtex, fiber length 40 mm, viscose rayon, product name: CD, manufactured by Daiwabo Rayon Co., Ltd., sedimentation speed of about 8 seconds, official moisture content of 11%
3.3T rayon: fineness 3.3 dtex, fiber length 40 mm, viscose rayon, product name: CD, manufactured by Daiwabo Rayon Co., Ltd., sedimentation speed of about 3 seconds, official moisture content of 11%

(hydrophilic synthetic fiber)
Hydrophilic hollow PET: Fineness 2.8 dtex, fiber length 51 mm, polyester fiber with a hollow cross-section with a hydrophilized surface (hollow ratio 30%), sedimentation speed of about 6 seconds, official moisture content of 0.7%
Hydrophilic PET: Fineness 1.6 dtex, fiber length 51 mm, surface-hydrophilized polyester fiber, trade name: Q201, manufactured by Toray Industries, Inc., sedimentation speed of about 3.4 seconds, official moisture content of 0.6%

[Hydrophobic fiber]
(water-repellent cellulose fiber)
Water repellent rayon: Fineness 1.7 dtex, fiber length 40 mm, viscose rayon treated with a non-fluorine water repellent on the fiber surface for water repellency, trade name: Eco Repellent, manufactured by Daiwabo Rayon Co., Ltd., sedimentation rate of 10 minutes or more, Official moisture content 12.8%

(hydrophobic synthetic fiber)
PET: fineness 1.45 dtex, fiber length 38 mm, polyethylene terephthalate fiber, trade name: T403, manufactured by Toray Industries, Inc., sedimentation rate of 1 minute or more, official moisture content 0.7%
Hollow PET: Fineness 1.45 dtex, fiber length 51 mm, polyester fiber having a hollow cross section (hollow ratio 30%), trade name: T453, manufactured by Toray Industries, Inc., sedimentation rate of 1 minute or more, official moisture content 0.7%
PET binder: fineness 2.2 dtex, fiber length 51 mm, heat adhesive polyethylene terephthalate fiber, trade name: T9611, manufactured by Toray Industries, Inc., sedimentation rate of 1 minute or more, official moisture content 0.7%
PP/PE: fineness 1.6 dtex, fiber length 51 mm, concentric core-sheath composite fiber (melting point: about 133°C), core: polypropylene, sheath: high-density polyethylene, product name: NBF (H) P, Daiwabo Co., Ltd. ), sedimentation rate of 1 minute or more, official moisture content of 0%

[Example 1]
(i) Preparation of first fibrous web 70% by mass of water-repellent rayon and 30% by mass of 1.7T rayon are mixed, and using ^a parallel carding machine, A first fibrous web was produced.

(ii) Preparation of second fibrous web 40% by mass of hollow PET, 30% by mass of PET binder and 30% by mass of 3.3T rayon are mixed, and the basis weight is about 17.5 g/m using a parallel carding machine. A second fibrous web was made so as to be ² .

(iii) Fabrication of nonwoven fabric The first fibrous web and the second fibrous web were laminated to fabricate a laminated fibrous web. This laminated fibrous web was placed on a support (90-mesh plain weave) and conveyed at a speed of 4 m/min, while a water stream with a water pressure of 2.0 MPa was sprayed once onto the surface of the second fibrous web. Subsequently, the surface of the first fibrous web was sprayed with a water jet of 2.5 MPa water pressure once. In this hydroentanglement treatment, a nozzle having orifices with a hole diameter of 0.12 mm provided at intervals of 0.6 mm was used. The distance between the nozzle and the laminated fibrous web was 20 mm. Subsequently, the fabric was dried at 80° C. and heat-treated with hot air at 140° C. for 10 seconds to obtain a nonwoven fabric.

[Examples 2 to 21, Comparative Examples 1 to 13]
Nonwoven fabrics were obtained in the same manner as in Example 1, except that the types and proportions of the fibers constituting the first and second fibrous webs were as shown in Tables 1 to 3.

However, in Examples 11 and 12 and Comparative Examples 2 and 12, after the entangling water flow treatment, the nonwoven fabric was used as a plain weave support manufactured by Daiwabo Co., Ltd. (warp: polyethylene terephthalate monofilament 0.47 mm × 0.76 mm, warp density 24 mesh / inch, weft: polyethylene terephthalate 0.75 mm, weft density 17 mesh/inch), and while conveying at a speed of 4 m / min, a water flow of 2.0 MPa water pressure is sprayed once on the surface of the first fiber web. bottom. Subsequently, after performing drying treatment at 80° C., it was heat-treated with hot air at 140° C. for 10 seconds to obtain a nonwoven fabric having irregularities (9% porosity).
In Comparative Examples 12 and 13, single-layer nonwoven fabrics were produced without heat treatment at 140°C for 10 seconds.

[evaluation]
Evaluation methods are as follows. Evaluation results are shown in Tables 1 to 3.
(contact angle)
The contact angle of each fiber layer of the produced nonwoven fabric was calculated as described above using the θ/2 method.

(thickness)
The thickness of the nonwoven fabric and each fiber layer was calculated as described above using image analysis software after photographing a cross section cut in the thickness direction of the nonwoven fabric with an SEM.

(Liquid Absorption Rate and Wet Back Property of Sample for 15cc)
A top sheet was peeled off from a commercially available light incontinence sheet (Procter & Gamble, Whisper (registered trademark) 1 sheet double role W guard). The produced nonwoven fabric was placed on the remaining ADL, and the periphery was fixed with packing tape. This was used as a sample for 15cc. The nonwoven fabric was placed so that the second fiber layer was in contact with the ADL.
A jig with an injection cylinder (height 75 mm, inner diameter 25 mm at the top of the cylinder, inner diameter 10 mm at the bottom of the cylinder) was placed on the first fiber layer. 15 cc of physiological saline (0.9% by mass) colored blue with a coloring agent (food blue No. 1) was put into the injection cylinder of the jig, and the time until all the saline was absorbed was measured. . It was also confirmed whether the physiological saline leaked out from the gap between the jig and the first fiber layer. If it leaks, it is unsuitable as a topsheet.

After 10 minutes have passed since the injection, 10 sheets of filter paper (manufactured by Toyo Roshi Kaisha, Ltd., trade name: ADVANTEC (registered trademark) No. 2, 10 cm × 10 cm) whose mass has been measured in advance are stacked and placed at the injection site. and a pressure of 1 kg/10 cm ² was applied for 20 seconds. After that, the mass of 10 filter papers was measured again. The difference in the mass of the 10 filter papers before and after the load test was defined as the wet back property (WB).

(Liquid Absorption Rate and Wet Back Property of Sample for 100cc)
A sample for 100 cc was obtained in the same manner as above except that ADL obtained from a commercially available light incontinence sheet (Procter & Gamble, Whisper (registered trademark) thin water absorption) was used.
The first liquid absorption rate and wet back property (1st WB) of the 100 cc sample were measured in the same manner as described above, except that the amount of physiological saline was 40 cc.

After 15 minutes from the measurement of the wet back property (1st WB), 40 cc of physiological saline was injected into the 100 cc sample again, and the second liquid absorption speed and wet back property (1st WB) were measured in the same manner as above. 2nd WB) was measured.

The thickness, contact angle, liquid absorption rate and wetback property shown in each table are average values for five samples.

The nonwoven fabrics of Examples 1 to 21 have an appropriate degree of hydrophilicity in the first and second fiber layers, so that they have a high liquid absorption rate and excellent wet back properties.

Since the first fiber layer of the nonwoven fabric of Comparative Example 1 is formed only from water-repellent cellulose fibers, the liquid absorption speed is slow in all samples. Furthermore, liquid leakage occurred when saline was injected into the 100cc sample.

In the nonwoven fabrics of Comparative Examples 2 to 4, the contact angle of the second fiber layer is less than 80°, and the ratio of the hydrophilic cellulose fibers in the second fiber layer is high. .

The nonwoven fabric of Comparative Example 5 has a slow liquid absorption speed in all samples because the second fiber layer is formed only from hydrophobic fibers. Furthermore, liquid leakage occurred when saline was injected into the 100cc sample.

In the nonwoven fabrics of Comparative Examples 6 to 11, the contact angle of at least one of the first and second fiber layers is less than 80°, and the ratio of hydrophilic cellulose fibers in the second fiber layer is high. Inferior to wet back property.

The nonwoven fabrics of Comparative Examples 12 and 13 do not have a layer corresponding to the second fiber layer. Therefore, Comparative Example 12 has a slow liquid absorption rate, and Comparative Example 13 is inferior in both liquid absorption rate and wet back property.

を満たす、態様１～４のいずれかの不織布。
（態様６）
前記第１繊維層に含まれる前記親水性繊維の含有量は、前記第１繊維層の総質量を基準として、７０質量％未満である、態様１～５のいずれかの不織布。
（態様７）
前記第２繊維層に含まれる前記親水性繊維の含有量は、前記第２繊維層の総質量を基準として、９０質量％以下である、態様１～６のいずれかの不織布。
（態様８）
前記第１繊維層に含まれる前記親水性繊維の繊度は、０．５ｄｔｅｘ以上３ｄｔｅｘ以下である、態様１～７のいずれかの不織布。
（態様９）
前記第１繊維層に含まれる前記親水性繊維は、親水性セルロース繊維を含む、態様１～８のいずれかの不織布。
（態様１０）
前記第２繊維層に含まれる前記親水性繊維は、親水性セルロース繊維を含む、態様１～９のいずれかの不織布。
（態様１１）
前記第１繊維層の表面は、凹凸および開孔の少なくとも一方を有する、態様１～１０のいずれかの不織布。
（態様１２）
第１繊維層と、
前記第１繊維層の一方の主表面に位置し、前記第１繊維層とは異なる第２繊維層と、を備え、
前記第１繊維層および前記第２繊維層は、繊維同士の交絡により一体化されており、
前記第１繊維層は、前記第１繊維層の総質量を基準として、撥水性セルロース繊維を３０質量％超え９０質量％以下含み、かつ、親水性繊維を１０質量％以上７０質量％未満含み、
前記第２繊維層は、疎水性繊維、および、
（ａ）親水性セルロース繊維を、前記第２繊維層の総質量を基準として５質量％以上４０質量％以下含む、
（ｂ）親水化合成繊維を、前記第２繊維層の総質量を基準として４０質量％以上９０質量％以下含む、あるいは、
（ｃ）親水性合成繊維を、前記第２繊維層の総質量を基準として３０質量％以上９０質量％以下含む、吸収性物品用不織布。
（態様１３）
前記第１繊維層の目付Ｗ１と前記第２繊維層の目付Ｗ２とは、以下の関係式：
１≦Ｗ２／Ｗ１≦３
を満たす、態様１２の不織布。
（態様１４）
前記第１繊維層に含まれる前記親水性繊維の繊度は、０．５ｄｔｅｘ以上３ｄｔｅｘ以下である、態様１２または１３の不織布。
（態様１５）
前記第１繊維層に含まれる前記親水性繊維は、親水性セルロース繊維を含む、態様１２～１４のいずれかの不織布。
（態様１６）
前記第２繊維層に含まれる疎水性繊維は、疎水性合成繊維を含む、態様１２～１５のいずれかの不織布。
（態様１７）
前記第１繊維層の表面は、凹凸および開孔の少なくとも一方を有する、態様１２～１６のいずれかの不織布。
（態様１８）
態様１～１７のいずれかの吸収性物品用不織布を含む、吸収性物品。
（態様１９）
前記吸収性物品用不織布は、前記第１繊維層が肌当接面になるように配置されている、態様１８の吸収性物品。
（態様２０）
第１繊維ウェブの総質量を基準として、撥水性セルロース繊維を３０質量％超え９０質量％以下含み、親水性繊維を１０質量％以上含む、前記第１繊維ウェブを作製すること、
疎水性繊維、および、第２繊維ウェブの総質量を基準として、
（ａ）親水性セルロース繊維を、前記第２繊維層の総質量を基準として５質量％以上４０質量％以下含む、
（ｂ）親水化合成繊維を、前記第２繊維層の総質量を基準として４０質量％以上９０質量％以下含む、あるいは、
（ｃ）親水性合成繊維を、前記第２繊維層の総質量を基準として３０質量％以上９０質量％以下含む、前記第２繊維ウェブを作製すること、
前記第１繊維ウェブと前記第２繊維ウェブとを重ね合わせて積層繊維ウェブを作製すること、および、
前記積層繊維ウェブを、高圧流体流を用いた交絡処理に付して繊維同士を交絡させること、を含む、
吸収性物品用不織布の製造方法。 The present disclosure includes the following aspects.
(Aspect 1)
a first fiber layer;
a second fiber layer located on one main surface of the first fiber layer and different from the first fiber layer;
The first fiber layer and the second fiber layer are integrated by entangling the fibers,
The first fiber layer contains more than 30% by mass and 90% by mass or less of water-repellent cellulose fibers and 10% by mass or more of hydrophilic fibers, based on the total mass of the first fiber layer,
The second fiber layer contains 5% by mass or more of hydrophilic fibers based on the total mass of the second fiber layer,
The contact angle θ1 between water and the first fiber layer surface and the contact angle θ2 between water and the second fiber layer surface before water permeation are both 75° or more. non-woven fabric.
(Aspect 2)
The nonwoven fabric according to aspect 1, wherein both the contact angle θ1 and the contact angle θ2 are 120° or less.
(Aspect 3)
The basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer are expressed by the following relational expression:
1≤W2/W1≤3
The nonwoven fabric of aspect 1 or 2, which satisfies
(Aspect 4)
The contact angle θ1 and the contact angle θ2 are expressed by the following relational expression:
-40°≤θ1-θ2≤30°
The nonwoven fabric of any one of aspects 1 to 3, which satisfies
(Aspect 5)
The contact angle θ2, the thickness T1 of the first fiber layer, and the thickness T2 of the second fiber layer are represented by the following relational expressions:

The nonwoven fabric according to any one of aspects 1 to 4, which satisfies
(Aspect 6)
The nonwoven fabric according to any one of aspects 1 to 5, wherein the content of the hydrophilic fibers contained in the first fibrous layer is less than 70% by mass based on the total mass of the first fibrous layer.
(Aspect 7)
The nonwoven fabric according to any one of aspects 1 to 6, wherein the content of the hydrophilic fibers contained in the second fibrous layer is 90% by mass or less based on the total mass of the second fibrous layer.
(Aspect 8)
The nonwoven fabric according to any one of aspects 1 to 7, wherein the hydrophilic fibers contained in the first fiber layer have a fineness of 0.5 dtex or more and 3 dtex or less.
(Aspect 9)
The nonwoven fabric according to any one of aspects 1 to 8, wherein the hydrophilic fibers contained in the first fibrous layer comprise hydrophilic cellulose fibers.
(Mode 10)
The nonwoven fabric according to any one of aspects 1 to 9, wherein the hydrophilic fibers contained in the second fibrous layer comprise hydrophilic cellulose fibers.
(Aspect 11)
11. The nonwoven fabric according to any one of aspects 1 to 10, wherein the surface of the first fibrous layer has at least one of irregularities and pores.
(Aspect 12)
a first fiber layer;
a second fiber layer located on one main surface of the first fiber layer and different from the first fiber layer;
The first fiber layer and the second fiber layer are integrated by entangling the fibers,
The first fiber layer, based on the total mass of the first fiber layer, contains more than 30% by mass of water-repellent cellulose fibers and less than 90% by mass, and contains 10% by mass or more and less than 70% by mass of hydrophilic fibers,
The second fiber layer comprises hydrophobic fibers, and
(a) containing 5% by mass or more and 40% by mass or less of hydrophilic cellulose fibers based on the total mass of the second fiber layer;
(b) contains 40% by mass or more and 90% by mass or less of the hydrophilic synthetic fiber based on the total mass of the second fiber layer, or
(c) A nonwoven fabric for absorbent articles, containing 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fiber layer.
(Aspect 13)
The basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer are expressed by the following relational expression:
1≤W2/W1≤3
The nonwoven fabric of aspect 12, wherein:
(Aspect 14)
The nonwoven fabric according to aspect 12 or 13, wherein the hydrophilic fibers contained in the first fiber layer have a fineness of 0.5 dtex or more and 3 dtex or less.
(Aspect 15)
15. The nonwoven fabric of any one of aspects 12-14, wherein the hydrophilic fibers contained in the first fibrous layer comprise hydrophilic cellulose fibers.
(Aspect 16)
16. The nonwoven fabric of any one of aspects 12-15, wherein the hydrophobic fibers contained in the second fibrous layer comprise hydrophobic synthetic fibers.
(Aspect 17)
17. The nonwoven fabric of any one of aspects 12 to 16, wherein the surface of the first fibrous layer has at least one of irregularities and open pores.
(Aspect 18)
An absorbent article comprising the nonwoven fabric for absorbent articles according to any one of aspects 1-17.
(Aspect 19)
19. The absorbent article according to aspect 18, wherein the nonwoven fabric for absorbent articles is arranged such that the first fiber layer is a skin-contacting surface.
(Aspect 20)
Producing the first fibrous web containing more than 30% by mass and not more than 90% by mass of water-repellent cellulose fibers and not less than 10% by mass of hydrophilic fibers based on the total mass of the first fibrous web;
Based on the total weight of the hydrophobic fibers and the second fibrous web,
(a) containing 5% by mass or more and 40% by mass or less of hydrophilic cellulose fibers based on the total mass of the second fiber layer;
(b) contains 40% by mass or more and 90% by mass or less of the hydrophilic synthetic fiber based on the total mass of the second fiber layer, or
(c) producing the second fibrous web containing 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fibrous layer;
overlapping the first fibrous web and the second fibrous web to form a laminated fibrous web; and
subjecting the laminated fiber web to an entangling treatment using a high-pressure fluid flow to entangle the fibers;
A method for producing a nonwoven fabric for absorbent articles.

The nonwoven fabric of the present disclosure is excellent in liquid absorption speed and wet back properties. Therefore, the nonwoven fabrics of the present disclosure are useful as topsheets for various absorbent articles.

Claims (20)

a first fiber layer;
a second fiber layer located on one main surface of the first fiber layer and different from the first fiber layer;
The first fiber layer and the second fiber layer are integrated by entangling the fibers,
The first fiber layer contains more than 30% by mass and 90% by mass or less of water-repellent cellulose fibers and 10% by mass or more of hydrophilic fibers, based on the total mass of the first fiber layer,
The second fiber layer contains 5% by mass or more of hydrophilic fibers based on the total mass of the second fiber layer,
The contact angle θ1 between water and the first fiber layer surface and the contact angle θ2 between water and the second fiber layer surface before water permeation are both 75° or more. non-woven fabric. The nonwoven fabric for absorbent articles according to claim 1, wherein both the contact angle θ1 and the contact angle θ2 are 120° or less. The basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer are expressed by the following relational expression:
1≤W2/W1≤3
The nonwoven fabric for absorbent articles according to claim 1 or 2, which satisfies The contact angle θ1 and the contact angle θ2 are expressed by the following relational expression:
-40°≤θ1-θ2≤30°
The nonwoven fabric for absorbent articles according to any one of claims 1 to 3, which satisfies The contact angle θ2, the thickness T1 of the first fiber layer, and the thickness T2 of the second fiber layer are represented by the following relational expressions:

The nonwoven fabric for absorbent articles according to any one of claims 1 to 4, which satisfies The absorption according to any one of claims 1 to 5, wherein the content of the hydrophilic fibers contained in the first fiber layer is less than 70% by mass based on the total mass of the first fiber layer. Non-woven fabric for sexual goods. The absorption according to any one of claims 1 to 6, wherein the content of the hydrophilic fibers contained in the second fiber layer is 90% by mass or less based on the total mass of the second fiber layer. Non-woven fabric for sexual goods. The nonwoven fabric for absorbent articles according to any one of claims 1 to 7, wherein the hydrophilic fibers contained in the first fiber layer have a fineness of 0.5 dtex or more and 3 dtex or less. The nonwoven fabric for absorbent articles according to any one of claims 1 to 8, wherein the hydrophilic fibers contained in the first fiber layer contain hydrophilic cellulose fibers. The nonwoven fabric for absorbent articles according to any one of claims 1 to 9, wherein the hydrophilic fibers contained in the second fiber layer contain hydrophilic cellulose fibers. The nonwoven fabric for absorbent articles according to any one of claims 1 to 10, wherein the surface of said first fiber layer has at least one of irregularities and pores. a first fiber layer;
a second fiber layer located on one main surface of the first fiber layer and different from the first fiber layer;
The first fiber layer and the second fiber layer are integrated by entangling the fibers,
The first fiber layer, based on the total mass of the first fiber layer, contains more than 30% by mass of water-repellent cellulose fibers and less than 90% by mass, and contains 10% by mass or more and less than 70% by mass of hydrophilic fibers,
The second fiber layer comprises hydrophobic fibers, and
(a) containing 5% by mass or more and 40% by mass or less of hydrophilic cellulose fibers based on the total mass of the second fiber layer;
(b) contains 40% by mass or more and 90% by mass or less of the hydrophilic synthetic fiber based on the total mass of the second fiber layer, or
(c) A nonwoven fabric for absorbent articles, containing 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fiber layer. The basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer are expressed by the following relational expression:
1≤W2/W1≤3
The nonwoven fabric for absorbent articles according to claim 12, which satisfies The nonwoven fabric for absorbent articles according to claim 12 or 13, wherein the hydrophilic fibers contained in the first fiber layer have a fineness of 0.5 dtex or more and 3 dtex or less. The nonwoven fabric for absorbent articles according to any one of claims 12 to 14, wherein the hydrophilic fibers contained in the first fiber layer contain hydrophilic cellulose fibers. The nonwoven fabric for absorbent articles according to any one of claims 12 to 15, wherein the hydrophobic fibers contained in said second fiber layer contain hydrophobic synthetic fibers. The nonwoven fabric for absorbent articles according to any one of claims 12 to 16, wherein the surface of said first fiber layer has at least one of irregularities and pores. An absorbent article comprising the nonwoven fabric for absorbent articles according to any one of claims 1 to 17. 19. The absorbent article according to claim 18, wherein the nonwoven fabric for absorbent articles is arranged such that the first fiber layer is a skin-contacting surface. Producing the first fibrous web containing more than 30% by mass and not more than 90% by mass of water-repellent cellulose fibers and not less than 10% by mass of hydrophilic fibers based on the total mass of the first fibrous web;
Based on the total weight of the hydrophobic fibers and the second fibrous web,
(a) containing 5% by mass or more and 40% by mass or less of hydrophilic cellulose fibers based on the total mass of the second fiber layer;
(b) contains 40% by mass or more and 90% by mass or less of the hydrophilic synthetic fiber based on the total mass of the second fiber layer, or
(c) producing the second fibrous web containing 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers based on the total mass of the second fibrous layer;
overlapping the first fibrous web and the second fibrous web to form a laminated fibrous web; and
A method for producing a nonwoven fabric for absorbent articles, comprising subjecting the laminated fiber web to an entangling treatment using a high-pressure fluid flow to entangle the fibers.