Nonwoven fabric for absorbent articles, manufacturing method thereof, and absorbent articles

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]

[0001] The present disclosure relates to a nonwoven fabric for an absorbent article, a method for producing the same, and an absorbent article. [Background technology]

[0002] Various absorbent articles, such as disposable diapers, sanitary napkins, incontinence pads, and panty liners, are available on the market. Nonwoven fabrics with a two-layer structure have been proposed as sheets for use in these absorbent articles that come into contact with the wearer's skin. For example, Patent Document 1 discloses a sheet having a first layer and a second layer, with the first layer, which comes into contact with the wearer's skin, being made of hydrophobic artificial cellulose fibers or polyester fibers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2015-507977 Summary of the Invention [Problem to be solved by the invention]

[0004] The nonwoven fabric of Patent Document 1 has an excellent wet-back property (rewet property) because the first layer on the skin side is formed from hydrophobic fibers, but on the other hand, it has a slow liquid absorption rate.

[0005] An object of the present disclosure is to provide a nonwoven fabric for absorbent articles that has excellent liquid absorption rate and wet-back property, a method for producing the same, and an absorbent article. [Means for solving the problem]

[0006] The present disclosure provides a nonwoven fabric for absorbent articles, comprising a first fiber layer and a second fiber layer different from the first fiber layer and located on one main surface of the first fiber layer, the first fiber layer and the second fiber layer being integrated by entanglement of fibers, the first fiber layer containing more than 30% by mass and not more than 90% by mass 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 containing 5% by mass or more of hydrophilic fibers, based on the total mass of the second fiber layer, and 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 permeates are both 75° or more.

[0007] The present disclosure also provides a nonwoven fabric for absorbent articles, comprising a first fiber layer and a second fiber layer different from the first fiber layer, the first fiber layer being located on one main surface of the first fiber layer, the second fiber layer being integrated by entanglement of fibers, the first fiber layer 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 and not more than 70% by mass of hydrophilic fibers, based on the total mass of the first fiber layer, and the second fiber layer containing hydrophobic fibers, and (a) containing not less than 5% by mass and not more than 40% by mass of hydrophilic cellulose fibers, based on the total mass of the second fiber layer, or (b) containing not less than 40% by mass and not more than 90% by mass of hydrophilized synthetic fibers, based on the total mass of the second fiber layer, or (c) containing not less than 30% by mass and not more than 90% by mass of hydrophilic synthetic fibers, based on the total mass of the second fiber layer.

[0008] The present disclosure also provides an absorbent article comprising the above-described nonwoven fabric for an absorbent article.

[0009] The present disclosure also provides a method for producing a first fibrous web, the first fibrous web containing more than 30% by mass and not more than 90% 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; 、5 Contains (b) hydrophilized synthetic fibers, containing % by mass or more and 40% by mass or less 、4 (c) Contains 0% by mass or more and 90% by mass or less of hydrophilic synthetic fibers、3 The present invention provides a method for producing a nonwoven fabric for absorbent articles, the method comprising: preparing the second fiber web containing 0% by mass or more and 90% by mass or less of the first fiber web; overlapping the first fiber web and the second fiber web to prepare a laminated fiber web; and subjecting the laminated fiber web to an entanglement treatment using a high-pressure fluid flow to entangle the fibers. [Effects of the Invention]

[0010] According to the present disclosure, there are provided a nonwoven fabric for absorbent articles having excellent liquid absorption rate and wet-back property, a method for producing the same, and an absorbent article. DETAILED DESCRIPTION OF THE INVENTION

[0011] From the perspective of the SDGs, industrial products are required to be derived from biomass (plants), biodegradable, and recyclable. Nonwoven fabrics for the surface of absorbent articles (hereafter referred to as topsheets) are no exception. Furthermore, because these topsheets come into contact with human skin, it is important that they are made from materials that are safe and reliable for users. Materials that meet these requirements include natural fibers such as cotton and lyocell. However, it is difficult to achieve the performance required of topsheets using only these natural fibers.

[0012] The performance required of a top sheet typically includes a high liquid absorption rate and excellent wet-back properties. Wet-back properties are the ability to prevent liquid once absorbed into an absorbent article from returning to the surface of the top sheet. Excellent wet-back properties refer to the ability to prevent liquid from returning. The liquid absorption rate is easily affected by the hydrophilicity of the top sheet, and the wet-back properties are easily affected by the water repellency of the top sheet.

[0013] In addition, topsheets are also required to be liquid-resistant. Liquid leakage occurs when an absorbent article is unable to absorb enough liquid. Liquid leakage is easily affected by the hydrophilicity of the first and second fibrous layers. If the surface of the first fibrous layer has excessively high water repellency, liquid cannot penetrate into the first fibrous layer and remains on the surface of the first fibrous layer. If the surface of the second fibrous layer has excessively high water repellency, liquid remains between the first and second fibrous layers, reducing the absorption rate. This results in liquid leakage. In the latter case, wetback properties are also reduced.

[0014] Because natural fibers are hydrophilic, top sheets formed from them have a relatively fast liquid absorption rate but poor wet-back properties, contrary to Patent Document 1. It has been proposed to apply a water repellent agent to a natural fiber sheet to improve the wet-back properties, but this increases the number of steps.

[0015] The present disclosure provides a nonwoven fabric suitable for use as a surface sheet (top sheet) in an absorbent article, comprising at least a first fibrous layer and a second fibrous layer. The first fibrous layer is the skin-contacting surface and contains water-repellent cellulose fibers. The first fibrous layer is also the layer that first comes into contact with the liquid to be absorbed. The water-repellent cellulose fibers impart hydrophobic properties to the first fibrous layer, further providing the user with a sense of security and safety.

[0016] By incorporating a specific amount of hydrophilic fibers as the material for the first fiber layer, the first fiber layer has both moderate hydrophilicity and water repellency. The moderate hydrophilicity of the first fiber layer increases the liquid absorption rate and suppresses liquid leakage. The moderate hydrophobicity of the first fiber layer allows liquid to quickly permeate the first fiber layer without remaining within the first fiber layer. As a result, the wet-back property is improved and the uncomfortable feeling of wetness is less likely to occur.

[0017] 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 that permeates the first fiber layer passes through the second fiber layer and is absorbed and dispersed by the absorption distribution layer (ADL) located inside. Therefore, the second fiber layer is required to have water repellency to allow liquid to permeate quickly. If the second fiber layer is highly hydrophilic, liquid tends to remain inside the second fiber layer. As a result, liquid tends to return to the inside, reducing wet-back properties. On the other hand, if the second fiber layer is excessively hydrophobic, liquid leakage may occur.

[0018] In a first embodiment of the present disclosure, the degree of hydrophilicity of each fiber layer is determined by setting the contact angle of both the first and second fiber layers to 75° or more. In a second embodiment of the present disclosure, the degree of hydrophilicity of each fiber layer is determined by specifying the configuration of each of the first and second fiber layers. This allows for both excellent liquid absorption rate and excellent wet-back properties without the need for post-processing.

[0019] That is, the nonwoven fabric for absorbent articles according to the first embodiment comprises a first fiber layer and a second fiber layer different from the first fiber layer and located on one main surface of the first fiber layer, the first fiber layer and the second fiber layer being integrated by entanglement of the fibers, the first fiber layer containing more than 30% by mass and not more than 90% by mass 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 containing 5% by mass or more of hydrophilic fibers, based on the total mass of the second fiber layer, and 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 permeates are both 75° or more.

[0020] The nonwoven fabric for absorbent articles according to the second embodiment comprises a first fiber layer and a second fiber layer different from the first fiber layer and located on one main surface of the first fiber layer, the first fiber layer and the second fiber layer being integrated by entanglement of the fibers. The first fiber layer contains more than 30% by mass and not more than 90% by mass of water-repellent cellulose fibers and 10% by mass or more but 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) 5% by mass or more and not more than 40% by mass of hydrophilic cellulose fibers, based on the total mass of the second fiber layer; (b) 40% by mass or more and not more than 90% by mass of hydrophilized synthetic fibers, based on the total mass of the second fiber layer; or (c) 30% by mass or more and not more than 90% by mass of hydrophilic synthetic fibers, based on the total mass of the second fiber layer.

[0021] The uses of absorbent articles vary, from those that absorb small amounts of high-viscosity liquids such as menstrual blood to those that absorb large amounts of low-viscosity liquids such as urine. Topsheets are also required to absorb liquids of various viscosities and amounts quickly and without backflow. The nonwoven fabric for absorbent articles according to the present disclosure achieves both excellent liquid absorption speed and excellent wet-back properties, regardless of the viscosity and amount of the liquid to be absorbed.

[0022] [Nonwoven fabric for absorbent articles] First, a configuration common to each embodiment will be described. The nonwoven fabric for absorbent articles according to the present disclosure includes a first fiber layer and a second fiber layer. Hereinafter, the nonwoven fabrics for absorbent articles according to the first and second embodiments may be collectively referred to simply as the nonwoven fabric.

[0023] Nonwoven fabric is defined in JIS L 0222 as "a fiber sheet, web or batt in which the fibers are oriented in one direction or randomly and are bonded by entanglement and / or fusion and / or adhesion, excluding paper, woven fabric, knitted fabric, tufted fabric and crepe felt."

[0024] In the nonwoven fabric, the fiber layers are stacked and integrated at least by entanglement of the fibers. This allows liquid that has permeated the first fiber layer to quickly penetrate into the second fiber layer, preventing it from accumulating between the layers. Furthermore, this also helps to prevent liquid that has permeated the first fiber layer from flowing back into the second fiber layer and leaking onto the surface of the first fiber layer.

[0025] Each fiber layer before lamination may be a nonwoven fabric or a precursor of a nonwoven fabric. A precursor of a nonwoven fabric is a fiber sheet, web, or batt in which the fibers are oriented unidirectionally or randomly but are not bonded to each other. The method for producing each fiber layer before lamination is not particularly limited. Each fiber layer (web) used to produce a nonwoven fabric may be a precursor of a nonwoven fabric produced by a carded method, an airlaid method, a wet method, or the like, or may be a nonwoven fabric produced by a hydroentanglement (spunlace) method, a spunbond method, a wet method, or the like.

[0026] (Metsuke) From the viewpoint of liquid absorption rate, it is desirable that the first fiber layer is not denser than the second fiber layer. From the viewpoint of liquid permeability, it is desirable that the second fiber layer is not 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 formula: 1≦W2 / W1≦3. W2 / W1 may be 1.2 or more, or 1.5 or more. W2 / W1 may be 2.8 or less, or 2.5 or less. Basis weight refers to mass per unit area.

[0027] The weight (W1+W2) of the nonwoven fabric is, for example, 25 g / m 2 More than 70g / m 2 When the basis weight of the entire nonwoven fabric is within this range, the liquid absorption rate can be increased without reducing the wet-back property. 2 or more, and 2 The basis weight of the nonwoven fabric may be 65 g / m or more. 2 may be less than 60 g / m 2 It may be the following:

[0028] (contact angle) It is desirable that the water repellency of the surfaces of the first and second fiber layers not differ significantly. If the hydrophilicity of the first fiber layer is excessively greater than that of the second fiber layer, the highly hydrophilic first fiber layer will absorb a large amount of liquid, but the highly water-repellent second fiber layer will have difficulty permeating all of this liquid. As a result, the liquid will tend to remain between the fiber layers, resulting in backflow and leakage. Conversely, if the water repellency of the first fiber layer is excessively greater than that of the second fiber layer, most of the liquid that was able to permeate the highly water-repellent first fiber layer will be retained by the highly hydrophilic second fiber layer. In this case, too, backflow is likely to occur.

[0029] 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 relation: -40°≦θ1−θ2≦30°. θ1−θ2 may be -38° or greater, or -35° or greater. θ1−θ2 may be 25° or less, or 20° or less.

[0030] The contact angle θ is determined by the θ / 2 method. Specifically, a sample (e.g., the first and second fiber layers before being integrated) is fixed on a base with double-sided tape or the like via a water-resistant film. A drop of distilled water colored with methylene blue is placed on the sample and allowed to stand for one minute. Next, the droplet on the sample is photographed from the side using a microscope (e.g., 3R-WM401WIFI, manufactured by 3R Systems Co., Ltd.). Assuming that the droplet is part of a perfect circle, the length (diameter 2r) of the line segment of the droplet in contact with the sample and the length (height h) between the outer edge of the droplet and a straight line passing through the center of the line segment and perpendicularly intersecting the line segment are determined by image analysis. From these values, the following formula is used: The contact angle θ is determined using TIFF0007752062000001.tif12150. The contact angle θ is the average value for multiple (typically, 5 or more) samples.

[0031] If the distilled water penetrates into the sample within 1 minute after being dropped, the contact angle is 0°.

[0032] The contact angle θ of the first and second fiber layers after integration can be determined in the same manner as above, with the nonwoven fabric fixed to a base so that the fiber layer to be measured faces upward.

[0033] Poor wetback properties can be caused by liquid remaining in the first and / or second fiber layer returning to the topsheet surface, as well as by liquid absorbed by the ADL seeping back through the second fiber layer. Therefore, it is desirable for the second fiber layer to be thick enough to prevent liquid seepage and to have suitable hydrophobicity. While the reason for this is unclear, these desirable properties can be expressed by the relationship between the thickness of the second fiber layer relative to the topsheet and the contact angle θ2 on the surface of the second fiber layer.

[0034] From the viewpoint of suppressing the seepage of liquid from the absorbent body, the contact angle θ2, the thickness T1 of the first fiber layer, and the thickness T2 of the second fiber layer may be related to each other by, for example, the following formula: You can fill TIFF0007752062000002.tif12150.

[0035] θ2×T2 / (T1+T2) may be equal to or greater than 45, or may be equal to or greater than 50. θ2×T2 / (T1+T2) may be equal to or less than 83, or may be equal to or less than 80.

[0036] In particular, from the viewpoint of the balance between the liquid absorption speed and the wet-back property, the following two relational expressions are used: -40°≦θ1-θ2≦30° It is desirable to simultaneously satisfy TIFF0007752062000003.tif12150.

[0037] (Thickness) From the viewpoint of liquid absorption rate, it is desirable that the first fiber layer be 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 relationship: T1 / T2≦1. T1 / T2 may be 0.95 or less, or may be 0.9 or less.

[0038] When the second fibrous layer is sufficiently thin (for example, 550 μm or less) or when it is used in an absorbent article that absorbs a relatively small amount of liquid (for example, less than 30 cc), the above relationship does not need to be taken into consideration.

[0039] The lower limit of T1 / T2 is not particularly limited. If the first fiber layer is too thin, the feel of the first fiber layer will be easily affected by the second fiber layer. For example, using thick, stiff fibers in the second fiber layer may reduce the feel of the first fiber layer. The lower limit of T1 / T2 may vary depending on the thickness T1 of the first fiber layer, but may be, for example, 0.2, 0.3, or 0.4.

[0040] The thickness of the first and second fiber layers after integration is calculated as follows. First, a cross section of the nonwoven fabric cut in the thickness direction is photographed using an SEM at a magnification of approximately 50 to 100 times. The magnification is set so that the entire thickness of the nonwoven fabric can be confirmed within the observation field. The cross section is obtained by placing the nonwoven fabric on a horizontal table with the second fiber layer facing downwards and cutting it in a direction perpendicular to the table.

[0041] The obtained image is imported into image analysis software (e.g., ImageJ), and five arbitrary straight lines are drawn parallel to the vertical outer edge of the image. Of the straight lines, the length of the line segments 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. The average length of the five line segments is taken as the thickness T of the entire nonwoven fabric. The arbitrary straight lines are drawn in a portion of the image where the contours of the lower and upper surfaces of the cross section are clearly defined. The length of the line segments is measured by connecting the outermost fibers that are clearly visible.

[0042] Similarly, the lengths of the line segments between the upper surface and the boundary between the two fiber layers are measured, and the average value is defined as the thickness T1 of the first fiber layer. The thickness T2 of the second fiber layer is calculated 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 determined by observing the fibers on a line drawn at random from the upper surface to the lower surface, and the point where fibers of different shapes and / or thicknesses first appear. The thickness is the average value of multiple samples (typically five or more).

[0043] 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 in this range, the wet-back 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 in this range, the liquid absorption rate is likely to be higher and breathability can also be improved. In one embodiment, the thickness T is 350 μm or more and 1300 μm or less.

[0044] (irregularities and / or openings) The surface of the first fibrous layer may have irregularities and / or open pores.

[0045] The unevenness can increase the surface area, which can increase the liquid absorption rate. Furthermore, depending on the method of forming the unevenness, areas with a high or low degree of entanglement between the first and second fiber layers may be created. In this case, the highly entangled areas can improve the integrity of the two fiber layers, while the less entangled areas can improve liquid permeability. In addition, the fabric can also be designed to have a decorative effect.

[0046] The irregularities may be a pattern applied to the surface of the first fiber layer, such as mesh, herringbone, stripes, or dots.

[0047] The pores allow liquid to quickly permeate through the first fiber layer, which can increase the liquid absorption rate. Furthermore, depending on the fabrication method, the first fiber layer and the second fiber layer may be integrally perforated. In this case, liquid can quickly permeate through both the first and second fiber layers, which can further increase the liquid absorption rate.

[0048] The apertures are desirably within a range that does not impair the effects of the first fiber layer (especially the wetback property). The aperture ratio is not limited as long as it is greater than 0%. The aperture ratio may be, for example, 5% or more. The aperture ratio may be, for example, 20% or less, or 15% or less. The aperture ratio is the ratio of the total area of ​​all apertures in the first fiber layer when viewed from the normal direction of the first fiber layer.

[0049] Next, the fibers used will be described. The term "hydrophilic" refers to the property of being easily compatible with water. The terms "water repellency" and "hydrophobicity" both refer to the property of being less compatible with water. "Hydrophobic" is a concept that includes "water repellency." In particular, "water repellency" refers to the property of repelling water.

[0050] The water affinity of a fiber can be evaluated by the sedimentation velocity (6(1)Ka) measured by the following method, for example, in accordance with the standard for medical gauze and medical absorbent cotton of Yakushokuki-hatsu No. 0630001.

[0051] Fibers before nonwoven fabric production or fibers extracted from nonwoven fabric are washed and rubbed three times for 2 minutes in warm water (approximately 40°C), then dried to remove any adhering oils and other contaminants. The fibers are then defibrated using a carding machine to prepare a fiber aggregate. 0.3 g of this fiber aggregate is rolled into balls with a diameter of 2 cm or less and gently dropped into water 200 mm deep from a height of 12 mm above the water surface at a temperature of 24-26°C. The time it takes for the fiber aggregate to sink below the water surface after being dropped is taken as the sedimentation velocity of the fiber.

[0052] If the fibers cannot be defibrated in a carding machine (for example, if the fibers are short), 0.3 g of the collected fibers can be rolled up and dropped into water. Alternatively, if the fibers are already in the form of a fiber aggregate (for example, a wet-laid or air-laid nonwoven fabric) and it is difficult to defibrate this in a carding machine, 0.3 g of nonwoven fabric pieces cut into 1 cm x 1 cm pieces can be dropped into water.

[0053] If the settling rate is less than 1 minute, the fiber is said to be "hydrophilic." If the settling rate is 1 minute or more, the fiber is said to be "hydrophobic." In particular, if a single drop of water is dropped on a nonwoven fabric made of only one type of fiber and there is almost no change in the shape of the drop after 10 seconds, the fiber can be evaluated as "water-repellent."

[0054] (Water-repellent cellulose fiber) The water-repellent cellulose fibers are contained in the first fibrous layer as hydrophobic fibers. The water-repellent cellulose fibers enhance the hydrophobicity of the fibrous layer and contribute to improving wet-back properties. The water-repellent cellulose fibers are flexible and derived from plants, making them suitable for use in the first fibrous layer, which is the surface that comes into contact with the skin.

[0055] Although cellulose fibers are inherently hydrophilic, in this disclosure, cellulose fibers to which water repellency has been artificially imparted are referred to as "water-repellent cellulose fibers."

[0056] The type of cellulose fiber is not particularly limited. Cellulose fibers include the following: (1) Natural fibers derived from plants such as cotton, flax, flax, ramie, jute, banana, bamboo, kenaf, shell ginger, hemp, and kapok; (2) solvent-spun cellulose fibers such as viscose-derived rayon and polynosic, cupra obtained by the cuprammonium process, and solvent-spun Tencel® and Lyocell, as well as other regenerated fibers; (3) Cellulose fibers obtained by melt spinning; (4) Semi-synthetic fibers such as acetate fibers; and (5) Pulp such as mechanical pulp, recycled pulp, and chemical pulp

[0057] The water-repellent cellulose fibers may be those obtained by adding a water-repellent agent to the cellulose fibers. Alternatively, the water-repellent cellulose fibers may be obtained by treating cellulose fibers having carboxyl groups and / or sulfonic acid groups with a treatment solution containing an isocyanate compound and a non-fluorine-based water-repellent agent. Water-repellent cellulose fibers obtained by such a method are disclosed, for example, in JP 2019-65443 A.

[0058] The water-repellent cellulose fibers preferably contain water-repellent rayon because the bending resistance of the nonwoven fabric is likely to be low. Rayon is also preferred because its cross-sectional shape is chrysanthemum-shaped, making it easy to effectively exhibit water repellency.

[0059] Examples of water-repellent rayon available on the market include Ecorepellent (trade name, water-repellent viscose rayon) manufactured by Daiwabo Rayon Co., Ltd. and Olea (trade name, water-repellent viscose rayon) manufactured by Kelheim Fibres GmbH. In particular, Ecorepellent (trade name) is preferably used because it exhibits high water repellency and has highly durable water repellency that is unlikely to decrease even when subjected to, for example, hydroentanglement treatment.

[0060] 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 embodiment, the fineness of the water-repellent cellulose fibers is 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, which tends to increase the liquid absorption rate. The fineness of the water-repellent cellulose fibers is not limited to the above range. Since it is particularly difficult to adjust the fineness of natural fibers, cellulose fibers with finenesses outside the above range may be used. Generally, the fineness of pulp is approximately 1.0 dtex to 4.0 dtex, and the fiber length is approximately 0.8 mm to 4.5 mm.

[0061] The fiber length of the water-repellent cellulose fibers is not particularly limited and may be appropriately selected depending on the material, its manufacturing method, the method for producing the fiber layer, the method for producing the nonwoven fabric, etc. The water-repellent cellulose fibers are, for example, short fibers. When the fiber layer is produced 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 above short fiber 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 embodiment, the fiber length of the water-repellent cellulose fibers may be 10 mm or more and 100 mm or less. When the fiber layer is produced from an airlaid web, the fiber length of the water-repellent cellulose fibers may be 2 mm or more and 20 mm or less.

[0062] In this embodiment, a plurality of water-repellent cellulose fibers may be used that differ in one or more of material, fiber length, and fineness.

[0063] The sedimentation rate of the water-repellent cellulose fibers is 1 minute or more, more preferably 5 minutes or more, and particularly preferably 10 minutes or more. It is particularly preferable that at least a portion of the water-repellent cellulose fibers does not sink below the water surface 10 minutes after the water-repellent cellulose fibers are dropped into water. At this time, the water-repellent cellulose fibers may have absorbed water. It is particularly preferable that some or all of the water-repellent cellulose fibers float on the water surface after 1 minute.

[0064] Water-repellent cellulose fibers possess water-repellent properties similar to those of conventional hydrophobic synthetic fibers, but this water-repellent property is exhibited only on the surface. The interior of water-repellent cellulose fibers still retains the ability to absorb and retain water. Therefore, the official moisture regain of water-repellent cellulose fibers (especially water-repellent rayon) is equivalent to that of the same type of cellulose fibers without water-repellent treatment. The secondary swelling of water-repellent cellulose fibers tends to be lower than that of untreated cellulose fibers but higher than that of general synthetic fibers. For example, some untreated viscose rayons have a secondary swelling (water swelling: measured according to JIS L1015:2010 8.26) of approximately 80% to 90%, while some water-repellent rayons have a secondary swelling of approximately 45% to 55%. Furthermore, some water-repellent rayons have an official moisture regain (measured according to JIS L1015) of approximately 10% to 13%. The official moisture regain of this water-repellent rayon is equivalent to the official moisture regain (11%) of ordinary rayon that has not been treated with water-repellent treatment.

[0065] (hydrophilic fiber) Hydrophilic fibers are fibers with a sedimentation rate of less than 1 minute as measured by the above method. Hydrophilic fibers enhance the hydrophilicity of the fiber layer, contributing to an improvement in the liquid absorption rate. Examples of hydrophilic fibers include hydrophilic cellulose fibers, natural animal fibers (silk, wool, etc.), hydrophilic synthetic fibers, and hydrophilized synthetic fibers.

[0066] The settling rate of the hydrophilic fibers is less than 1 minute, may be 50 seconds or less, may be 45 seconds or less, or may be 30 seconds or less.

[0067] <Hydrophilic cellulose fiber> The term "hydrophilic cellulose fibers" is used to distinguish them from water-repellent cellulose fibers, and refers to cellulose fibers that have not been given water-repellent properties and have inherent hydrophilicity. Examples of hydrophilic cellulose fibers, their fineness and fiber length are the same as those described for water-repellent cellulose fibers.

[0068] The hydrophilic cellulose fibers may be natural fibers, pulp, regenerated fibers, or semi-synthetic fibers. Pulp is produced, for example, from softwood or hardwood by conventional methods. Pulp includes, for example, mechanical pulp, regenerated pulp, and chemical pulp. The hydrophilic cellulose fibers having a fiber length of less than 10 mm may be pulp, or cut regenerated or semi-synthetic fibers. From the viewpoint of flexibility, the hydrophilic cellulose fibers may include regenerated fibers, especially rayon.

[0069] <Hydrophilic synthetic fiber> Hydrophilic synthetic fibers are synthetic fibers whose sedimentation rate measured by the above method is less than 1 minute. Hydrophilic synthetic fibers have hydroxyl groups derived from the raw material or are inherently hydrophilic, and typically have an official moisture regain of 2% or more. Examples of hydrophilic synthetic fibers include aramid fibers, vinylon fibers, nylon fibers, and acrylic fibers. Synthetic fibers will be described in more detail below.

[0070] <Hydrophilized synthetic fiber> Hydrophilized synthetic fibers are also synthetic fibers with a sedimentation rate of less than 1 minute as measured by the above method. However, hydrophilized synthetic fibers can be obtained by subjecting the above hydrophilic synthetic fibers and other synthetic fibers (hereinafter sometimes referred to as "hydrophobic synthetic fibers") to hydrophilization treatment. Examples of hydrophilization treatments include corona discharge treatment, sulfonation treatment, graft polymerization treatment, kneading a hydrophilizing agent into the fiber, and applying a durable oil agent.

[0071] <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 include hydrophilic cellulose fibers. Hydrophilic cellulose fibers are derived from plants and are therefore particularly suitable for use in the first fiber layer, which is the surface that comes into contact with the skin. Furthermore, from the perspective of the SDGs, the first hydrophilic fibers may be hydrophilic cellulose fibers.

[0072] The fineness of the first hydrophilic fiber is appropriately selected depending on the fineness of the other fibers to be mixed. The fineness of the first hydrophilic fiber may be the same as that of the water-repellent cellulose fiber. The fineness of the first hydrophilic fiber 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 fiber may be 6.0 dtex or less, 5.0 dtex or less, or 3.0 dtex or less. In one embodiment, the fineness of the first hydrophilic fiber is 0.3 dtex or more and 6 dtex or less. When the fineness of the first hydrophilic fiber is in this range, the liquid absorption rate is likely to be higher.

[0073] In one embodiment, the fineness of the first hydrophilic fiber is 0.5 dtex or more and 3 dtex or less. When the fineness of the first hydrophilic fiber is in this range, a sufficient liquid absorption rate is likely to be obtained even when a relatively large amount of liquid (e.g., 30 cc or more) is applied. The fineness of the first hydrophilic fiber may be 1.0 dtex or more, or 1.4 dtex or more. The fineness of the first hydrophilic fiber may be 2.5 dtex or less, or 2.0 dtex or less.

[0074] The fiber length of the first hydrophilic fibers is not particularly limited, and as described above, may be appropriately selected depending on the material, its manufacturing method, the method for producing the first fiber layer, the manufacturing method of the nonwoven fabric, etc. The fiber length of the first hydrophilic fibers may be the same as that of the water-repellent cellulose fibers.

[0075] 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 follows, for example, the "Types of Fibers, etc." in the "Terminology for Fiber Names" published by the Consumer Affairs Agency (https: / / www.caa.go.jp / policies / policy / representation / household_goods / guide / fiber / fiber_term.html).

[0076] <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 at least one hydrophilic fiber selected from the group consisting of hydrophilic cellulose fibers, hydrophilic synthetic fibers, and hydrophilized synthetic fibers. Details of each fiber are as described above. The second embodiment specifies an embodiment in which the second fiber layer contains hydrophilic cellulose fibers, hydrophilized synthetic fibers, or hydrophilic synthetic fibers as the hydrophilic fibers.

[0077] The fineness of the second hydrophilic fiber is appropriately selected depending on the fineness of the other fibers to be mixed. The fineness of the second hydrophilic fiber may be the same as that of the hydrophobic fiber. The fineness of the second hydrophilic fiber is, for example, 1.0 dtex or more, 1.5 dtex or more, or 2.0 dtex or more. The fineness of the second hydrophilic fiber is, for example, 6.0 dtex or less, 5.0 dtex or less, or 4.0 dtex or less. When the fineness of the second hydrophilic fiber is within this range, liquid permeability is easily improved and strength is easily ensured. In addition, the second fiber layer is easily made uniform.

[0078] The fiber length of the second hydrophilic fibers is not particularly limited and is appropriately selected depending on the material, its manufacturing method, the manufacturing method of the second fiber layer, the manufacturing method of the nonwoven fabric, etc., as described above. When the second fiber 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 more, 20 mm or more, or 30 mm or more. In the above case, in one embodiment, 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.

[0079] The second fibrous layer may contain a plurality of types of hydrophilic fibers that differ in one or more of material, fiber length, and fineness.

[0080] (hydrophobic fiber) The hydrophobic fibers enhance the hydrophobicity of the fibrous layer and contribute to improving the wetback property. Examples of hydrophobic fibers include water-repellent cellulosic fibers and hydrophobic synthetic fibers.

[0081] The sedimentation rate of the hydrophobic synthetic fibers is 1 minute or more, more preferably 5 minutes or more, and particularly preferably 10 minutes or more.

[0082] Details of the water-repellent cellulose fibers are as described above.

[0083] <Synthetic fiber> The hydrophilicity and official moisture regain of synthetic fibers depend mainly on the raw material. The raw material for synthetic fibers is generally a thermoplastic resin. The thermoplastic resin may be at least one selected from the group consisting of polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate, and copolymers thereof; polyolefin resins such as polypropylene, polyethylene (including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, propylene copolymers (including propylene-ethylene copolymers and propylene-butene-1-ethylene copolymers) with propylene as the main component, ethylene-vinyl alcohol copolymers, and ethylene-vinyl acetate copolymers; polyamide resins such as nylon 6, nylon 12, and nylon 66; acrylic resins; polyurethane resins; engineering plastics such as polycarbonate, polyacetal, polystyrene, polyphenylene sulfide, and cyclic polyolefins, and elastomers thereof.

[0084] Synthetic fibers may be single fibers made of a single component (also referred to as a "single section") and / or composite fibers made of multiple components (also referred to as "sections"). The composite fibers may be, for example, concentric or eccentric sheath-core composite fibers, islands-in-the-sea composite fibers, side-by-side composite fibers, or splittable composite fibers. The cross section of the fiber may be circular or noncircular. Noncircular shapes include elliptical, Y-shaped, X-shaped, I-shaped, multilobal, polygonal, and star-shaped. Synthetic fibers may have a hollow cross section, which tends to improve the bulkiness of nonwoven fabrics and increase the internal voids.

[0085] In both the monofilament and the bicomponent fibres, each section of the fibre may be made of one type of resin or may be made of a mixture of two or more types of resins.

[0086] In composite fibers, two or more components may be arranged so that the thermoplastic resin with the lowest melting point constitutes part of the fiber surface. In this case, when heat is applied in the process of producing a nonwoven fabric under conditions that melt or soften the component consisting of the thermoplastic resin with the lowest melting point (hereinafter referred to as the "low-melting component"), the low-melting component becomes the adhesive component. Such synthetic fibers can function as adhesive fibers.

[0087] The resin combinations (1st / 2nd) that make up composite fibers, which are made up 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, include, for example, combinations of polyester-based resins and polyolefin-based resins, such as polyethylene terephthalate / polyethylene, polyethylene terephthalate / polypropylene, and polyethylene terephthalate / propylene copolymers, as well as combinations of two types of polyolefin-based thermoplastic resins, such as polypropylene / polyethylene and polypropylene / propylene copolymers, and combinations of two types of polyester-based resins with different melting points.

[0088] Alternatively, the combination of the first and second components may be a combination of biodegradable resins, which 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.

[0089] Alternatively, the combination of the first and second components may be a thermoplastic resin made from plant-derived raw materials (biomass raw materials). This combination allows for a higher proportion of biomass raw materials in the nonwoven fabric. Specific resin combinations include a first component made from biopolyester / biopolyethylene, biopolyester / biopolypropylene, biopolypropylene / biopolyethylene, or polylactic acid / polybutylene succinate.

[0090] The number of divisions of the splittable conjugate fiber (i.e., 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. The fineness of the splittable conjugate fiber after division may be, for example, 0.1 dtex or more and 1.0 dtex or less.

[0091] <Hydrophobic fiber contained in the first fiber layer> The hydrophobic fibers contained in the first fibrous layer are water-repellent cellulose fibers as described above. The first fibrous layer may contain multiple types of hydrophobic fibers that differ in one or more of material, fiber length, and fineness.

[0092] <Hydrophobic fiber contained in the second fiber layer> The hydrophobic fibers that can be contained in the second fiber layer (hereinafter referred to as "second hydrophobic fibers") are not particularly limited. The second hydrophobic fibers may include at least one of water-repellent cellulose fibers and hydrophobic synthetic fibers. From the viewpoint of ensuring strength, the second hydrophobic fibers may include hydrophobic synthetic fibers.

[0093] The fineness of the second hydrophobic fiber is appropriately selected depending on the fineness of the other fibers to be mixed. The fineness of the second hydrophobic fiber may be the same as that of the second hydrophilic fiber. The fineness of the second hydrophobic fiber may be, for example, 1.0 dtex or more, 1.5 dtex or more, or 2.0 dtex or more. The fineness of the second hydrophilic fiber may be, for example, 6.0 dtex or less, 5.0 dtex or less, or 4.0 dtex or less.

[0094] The fiber length of the second hydrophobic fibers is not particularly limited, and as described above, may be appropriately selected depending on the material, its manufacturing method, the method for producing the second fiber layer, the manufacturing method for the nonwoven fabric, etc. The fiber length of the second hydrophobic fibers may be the same as that of the second hydrophilic fibers.

[0095] The second fibrous layer may contain a plurality of types of hydrophobic fibers that differ in one or more of material, fiber length, and fineness.

[0096] <Adhesive fiber> Each fibrous layer (typically the second fibrous layer) may contain adhesive fibers that bond the fibers together, thereby improving the strength of the laminated nonwoven fabric and preventing excessive stretching.

[0097] The adhesive fiber may be, for example, the synthetic fiber described above. The adhesive fiber may be a synthetic fiber contained in the fiber layer in a state where it exhibits adhesiveness. In this case, the synthetic fiber may be hydrophobic or hydrophilic, or may have been subjected to a hydrophilization treatment. The fineness and fiber length of the adhesive fiber may be similar to those of the synthetic fiber.

[0098] (I) First embodiment The nonwoven fabric for absorbent articles according to the first embodiment (hereinafter referred to as nonwoven fabric A) comprises a first fiber layer and a second fiber layer located on one main surface of the first fiber layer. The first fiber layer and the second fiber layer are integrated by entanglement of the fibers. The first fiber layer contains more than 30% by mass and not more than 90% by mass 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. Before water permeates, 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 greater.

[0099] Both the first and second fiber layers contain a certain amount of hydrophilic fibers, which gives each fiber layer appropriate hydrophilicity and allows liquids to easily permeate through them, resulting in a high liquid absorption rate.

[0100] Because both the first and second fiber layers have contact angles of 75° or greater, liquid quickly reaches the ADL without accumulating within each layer. Additionally, liquid absorbed in the ADL is quickly dispersed and transferred to the absorbent layer, and the high water repellency of the first and second fiber layers prevents it from seeping out to the surface of the topsheet. These effects improve wetback properties. If the contact angles θ1 and θ2 are less than 75°, the hydrophilicity is too high, and liquid tends to accumulate within the layers without penetrating. This results in poor wetback properties.

[0101] The 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 rate may be increased. When the contact angle θ2 of the second fiber layer is 120° or less, liquid retention between the first and second fiber layers is more likely to be suppressed.

[0102] In one embodiment, the contact angle θ of each of the first and second fiber layers is 75° to 120°. When the contact angle between the surfaces of the first and second fiber layers and water is 75° to 120° (hereinafter, this may be referred to as weak water repellency), the balance between liquid permeability and liquid return inhibition is improved, making it easier to achieve both a high liquid absorption rate and excellent wet-back properties.

[0103] (First fiber layer A) The first fiber layer in the first embodiment (hereinafter referred to as the first fiber layer A) is the surface that comes into contact with the skin. The first fiber layer A contains water-repellent cellulose fibers. The water-repellent cellulose fibers are contained in the first fiber 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 fiber layer. If the content of the water-repellent cellulose fibers is 30% by mass or less, the wet-back property is likely to decrease. If the content of the water-repellent cellulose fibers exceeds 90% by mass, the liquid absorption rate is likely to decrease. The content of the water-repellent cellulose fibers may be 40% by mass or more, or may be 50% by mass or more. The content of the water-repellent cellulose fibers may be 85% by mass or less, or may be 80% by mass or less.

[0104] The hydrophilic fiber is in the first fiber layer A. The relevantThe content of the hydrophilic fibers is 10% by mass or more based on the total mass of the fiber layer. If the content of the hydrophilic fibers is less than 10% by mass, the water repellency of the first fiber layer A will be too high, resulting in a slower liquid absorption rate and even liquid leakage. The content of the hydrophilic fibers may be 15% by mass or more, or 20% by mass or more. The content of the hydrophilic fibers is, for example, less than 70% by mass, or 60% by mass or less, or 50% by mass or less. In one embodiment, the content of the 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 appeal to users, hydrophilic cellulose fibers may be used.

[0105] The first fibrous layer A may contain fibers other than the water-repellent cellulosic fibers and hydrophilic fibers, such as hydrophobic synthetic fibers and adhesive fibers.

[0106] The mass proportion of the other fibers may be 30% by mass or less, 20% by mass or less, 10% by mass or less, 8% by mass or less, or 5% by mass or less, based on the total mass of the fiber layer. From the viewpoint of wet-back property and liquid absorption rate, the first fiber layer A may be composed of only water-repellent cellulose fibers and hydrophilic fibers. In particular, from the viewpoint of appeal to users, the first fiber layer A may be composed of only two types of fibers: water-repellent cellulose fibers and hydrophilic cellulose fibers.

[0107] The above content ratio of each fiber refers to the ratio of the fiber contained in the first fiber layer A before it is integrated with other layers. For example, in a nonwoven fabric, even if some of the fibers constituting the second fiber layer are mixed into the first fiber layer A, 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 described below.

[0108] The basis weight W1 of the first fiber layer A is not particularly limited. 2 or more, and 2 may be 15 g / m or more, 2If the basis weight W1 is in this range, the fibers of the first and second fiber layers are easily entangled with each other. 2 or less, and 2 may be less than or equal to 30 g / m 2 When the basis weight W1 is in this range, the liquid absorption rate tends to be higher. In one embodiment, the basis weight W1 is 10 g / m or less. 2 More than 35g / m 2 The following is the result.

[0109] 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 in this range, the wet-back 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 in this range, the liquid absorption rate is likely to be higher. In one embodiment, the thickness T1 is 120 μm or more and 500 μm or less.

[0110] (Second fiber layer A) The second fiber layer (hereinafter referred to as the second fiber layer A) in the first embodiment allows liquid to quickly penetrate the ADL and prevents liquid from returning from the ADL, thereby contributing to improved wetback properties. Furthermore, the second fiber layer A ensures the strength of the topsheet.

[0111] The second fiber layer A contains hydrophilic fibers in an amount of 5% by mass or more, based on the total mass of the second fiber layer A. This provides appropriate hydrophilicity and increases the liquid absorption rate. If the hydrophilic fibers are less than 5% by mass, liquid that has permeated the first fiber layer A tends to accumulate 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 of hydrophilic fibers in the second fiber layer A is appropriately set depending on the type of fiber.

[0112] The other configuration of the second fiber layer A is not particularly limited as long as the contact angle θ2 is 75° or more. The second fiber layer A may contain hydrophobic fibers in addition to 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 below.

[0113] (II) Second embodiment The nonwoven fabric for absorbent articles according to the second embodiment (hereinafter referred to as nonwoven fabric B) comprises a first fiber layer and a second fiber layer located on one main surface of the first fiber layer. The first and second fiber layers are integrated by entanglement of the fibers. The first fiber layer contains more than 30% by mass and not more than 90% by mass of water-repellent cellulosic fibers and 10% by mass to 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) 5% by mass to 40% by mass of hydrophilic cellulosic fibers, based on the total mass of the second fiber layer; (b) 40% by mass to 90% by mass of hydrophilized synthetic fibers, based on the total mass of the second fiber layer; or (c) 30% by mass to 90% by mass of hydrophilic synthetic fibers, based on the total mass of the second fiber layer.

[0114] By using fibers (a), (b), or (c) constituting the second fiber layer, the surface can be given appropriate water repellency, thereby improving the wetback property of nonwoven fabric B.

[0115] 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.

[0116] In one embodiment, the contact angle θ of each of the first and second fiber layers is 75° or more and 120° or less. The weakly water-repellent surfaces of the first and second fiber layers improve the balance between liquid permeability and liquid return prevention, making it easier to achieve both an excellent liquid absorption rate and excellent wet-back properties.

[0117] (First fiber layer) The first fiber layer in the second embodiment (hereinafter referred to as the first fiber layer B) is the surface that comes into contact with the skin. The first fiber layer B contains a specific ratio of water-repellent cellulose fibers and hydrophilic fibers. Therefore, the first fiber layer B has both moderate water-repellent and hydrophilic properties. In addition, the inclusion of cellulose fibers in the first fiber layer that comes into contact with the skin gives the user a sense of security and safety, and can exert a strong appeal.

[0118] The water-repellent cellulose fiber is contained in the first fiber layer B in an amount of more than 30 mass % and not more than 90 mass % based on the total mass of the fiber layer. The content of the water-repellent cellulose fiber in the first fiber layer B may be in the same range as that of the water-repellent cellulose fiber contained in the first fiber layer A.

[0119] The first fiber layer B contains hydrophilic fibers. The hydrophilic fibers are 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 is likely to decrease and liquid leakage may occur. If the hydrophilic fiber content exceeds 70% by mass, the wet-back property is likely to decrease. The hydrophilic fiber content may be 15% by mass or more, or may be 20% by mass or more. The hydrophilic fiber content may be 60% by mass or less, or may be 50% by mass or more.

[0120] The first fibrous layer B may contain fibers other than the water-repellent cellulose fibers and hydrophilic fibers. Examples of the types and mass proportions of the other fibers include those in the same range as those of the other fibers contained in the first fibrous layer A. From the viewpoint of wet-back property and liquid absorption rate, the first fibrous layer B may be composed only of water-repellent cellulose fibers and hydrophilic fibers.

[0121] 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).

[0122] (Second fiber layer B) The role of the second fiber layer (hereinafter referred to as 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, which gives the second fiber layer B appropriate hydrophilicity and water repellency.

[0123] Representative examples of hydrophobic fibers 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 of the hydrophobic fibers is appropriately determined depending on the type and content of the hydrophilic fibers.

[0124] Hydrophilic fibers include hydrophilic cellulose fibers, hydrophilized synthetic fibers, and hydrophilic synthetic fibers. Hydrophilic cellulose fibers, hydrophilized synthetic fibers, and hydrophilic synthetic fibers are all collectively referred to as hydrophilic fibers, but they have different properties. As described above, the second fiber layer is required to have high absorbency, which allows liquid to be quickly transferred to the ADL, as well as excellent wet-back properties. Therefore, it is desirable for liquid to be adequately retained within the second fiber layer. The content ratio of the various hydrophilic fibers described above is determined by taking into consideration their properties and the balance between absorbency and liquid retention.

[0125] (a) Hydrophilic cellulose fibers Hydrophilic cellulose fibers have high hydrophilicity, and therefore have excellent liquid absorption properties but also tend to retain excessive liquid. Therefore, when the second fiber layer B contains hydrophilic cellulose fibers, the content of the hydrophilic cellulose fibers is set to 5% by mass or more and 40% by mass or less, based on the total mass of the second fiber layer B. This allows the second fiber layer B to exhibit appropriate water repellency (e.g., a contact angle of 75° or more), and prevents excessive liquid retention within the second fiber layer B.

[0126] The content of hydrophilic cellulose fibers may be 8% by mass or more, 10% by mass or more, or 15% by mass or more, and may be 35% by mass or less, 30% by mass or less, or 25% by mass or less.

[0127] (b) When hydrophilic synthetic fibers are included Hydrophilized synthetic fibers are hydrophobic synthetic fibers that have been hydrophilized, and therefore have liquid retention properties, but the level of retention is not as high as that of hydrophilic cellulose fibers. Therefore, the second fiber layer B can contain more hydrophilized synthetic fibers than hydrophilic cellulose fibers. When the second fiber layer B contains hydrophilized synthetic fibers, the content of the hydrophilized synthetic fibers is 40% by mass or more and 90% by mass or less, based on the total mass of the second fiber layer B. This allows the second fiber layer B to exhibit appropriate water repellency (e.g., a contact angle of 75° or more), and the second fiber layer B exhibits appropriate liquid retention properties.

[0128] The content of the hydrophilized synthetic fibers may be 43% by mass or more, 45% by mass or more, or 48% by mass or more. The content of the hydrophilized synthetic fibers may be 85% by mass or less, 80% by mass or less, or 75% by mass or less.

[0129] (c) When hydrophilic synthetic fibers are included Hydrophilic synthetic fibers have lower swelling properties and lower liquid absorption and retention than hydrophilic cellulose. On the other hand, the liquid retention of hydrophilic synthetic fibers can be higher than that of hydrophilized synthetic fibers. Therefore, when the second fiber layer B contains hydrophilic synthetic fibers, the content of the hydrophilic synthetic fibers is 30% by mass or more and 90% by mass or less, based on the total mass of the second fiber layer B. This allows the second fiber layer B to exhibit appropriate water repellency (e.g., a contact angle of 75° or more) and appropriate liquid retention.

[0130] The content of hydrophilic synthetic fibers may be 35% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 85% by mass or less, 80% by mass or less, or 75% by mass or less.

[0131] The second fiber layer (B) may further contain adhesive fibers from the viewpoint of strength. The adhesive fibers are classified as hydrophilic or hydrophobic fibers depending on the degree of hydrophilicity. The mass proportion 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 proportion 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).

[0132] The basis weight W2 of the second fiber layer B is not particularly limited. 2 or more, and 2 may be 15 g / m or more, 2 If the basis weight W2 is in this range, the fibers of the first and second fiber layers are easily entangled with each other. 2 or less, and 2 may be less than or equal to 30 g / m 2 When the basis weight W2 is in this range, the liquid absorption rate tends to be faster. In one embodiment, the basis weight W2 is 10 g / m or less. 2 More than 35g / m 2 The basis weight W1 of the first fiber layer and the basis weight W2 of the second fiber layer may satisfy the relational formula: 1≦W2 / W1≦3.

[0133] The thickness T2 of the second fiber layer B is not particularly limited. The thickness T2 may be 200 μm or more, 210 μm or more, or 220 μm or more. When the thickness T2 is in this range, the wet-back property can be further improved. The thickness T2 may be 800 μm or less, 780 μm or less, or 770 μm or less. When the thickness T2 is in this range, the liquid absorption rate is likely to be higher. In one embodiment, 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.

[0134] [Absorbent articles] An absorbent article according to the present disclosure comprises a nonwoven fabric according to the present disclosure. In an absorbent article, the nonwoven fabric according to the present disclosure is arranged, for example, so that the first fibrous layer is the skin-contacting surface, i.e., the nonwoven fabric according to the present disclosure is used as a top sheet of the absorbent article, and the first fibrous layer is arranged closer to the user's skin.

[0135] The absorbent article comprises, for example, a nonwoven fabric (top sheet) according to the present disclosure, a back sheet, an absorbent dispersion layer (ADL) disposed between the top sheet and the back sheet, and an absorbent body. The back sheet is liquid-impermeable. The configuration of the ADL is not particularly limited. The ADL may be composed of, for example, an air-laid nonwoven fabric, a spunlace nonwoven fabric, an air-through nonwoven fabric, or a foam material containing hydrophilic or hydrophobic synthetic fibers. The absorbent body serves to absorb and retain liquid components that have permeated the top sheet and the ADL. Examples of the absorbent body include pulp and high-molecular-weight absorbent polymer (also known as SAP).

[0136] The use of the absorbent article is not particularly limited. The absorbent article may be one that absorbs a small amount of high-viscosity liquid such as menstrual blood, or one that absorbs a large amount of low-viscosity liquid such as urine. The nonwoven fabric of the present disclosure exhibits excellent liquid absorption speed and excellent wet-back properties regardless of the viscosity and amount of the liquid to be absorbed.

[0137] Specific examples of absorbent articles include diapers, incontinence pads, napkins, and panty liners.

[0138] [Method for manufacturing nonwoven fabric for absorbent articles] The nonwoven fabric according to this embodiment can be produced, for example, by a method including preparing a first fiber web that forms the first fiber layer and a second fiber web that forms the second fiber layer, stacking these to prepare a laminated fiber web, and subjecting the laminated fiber web to an entanglement treatment using a high-pressure fluid flow to entangle the fibers.

[0139] (1) Preparation of laminated fiber web First, a first fibrous web and a second fibrous web are prepared. As described above, each fiber web may be a precursor of a nonwoven fabric produced by a carded method, an airlaid method, a wet method, etc., or may be a nonwoven fabric produced by a spunlace method, a spunbond method, a wet method, etc. In particular, from the viewpoint of softness, each fiber web may be a precursor of a nonwoven fabric or a nonwoven fabric produced by a carded method, an airlaid method, a wet method, etc.

[0140] 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, and the basis weights of 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.

[0141] The first fibrous web and the second fibrous web are overlapped to form a laminated fibrous web.

[0142] (2) Interleaving The laminated fiber web is subjected to an entanglement treatment using a high-pressure fluid flow to entangle the fibers, thereby obtaining a nonwoven fabric in which the first fiber layer and the second fiber layer are integrated by entanglement of the fibers.

[0143] Examples of high-pressure fluids include high-pressure gases such as compressed air and high-pressure liquids such as high-pressure water. Below, the method for producing a nonwoven fabric according to the present disclosure will be described using an example in which high-pressure water (hereinafter also simply referred to as "water flow") is used as the high-pressure fluid, but the present disclosure is not limited to this.

[0144] The hydroentanglement treatment is carried out by placing the laminated fiber web on a support and spraying a columnar water stream onto it. The support is, for example, a plain weave of 80 mesh or more and 100 mesh or less. The water stream is sprayed from a nozzle having orifices with a hole diameter of 0.05 mm or more and 0.5 mm or less, spaced at intervals of 0.3 mm or more and 1.5 mm or less. The water pressure is, for example, 1 MPa or more and 15 MPa or less. The water pressure may be 10 MPa or less, or may be 7 MPa or less. The water stream is sprayed 1 to 5 times onto each of the front and back surfaces of the laminated fiber web.

[0145] (3) Formation of irregularities and / or openings After the entanglement treatment, irregularities and / or openings may be formed on the first fiber web side of the laminated fiber web, thereby obtaining a nonwoven fabric comprising a first fiber layer having irregularities and / or openings on the surface.

[0146] The irregularities are formed, for example, by hydroentangling a support on which one or more selected from convex portions, concave portions, and openings are regularly arranged. Alternatively, the irregularities are formed by hydroentangling using 1) a nozzle in which minute orifices from which high-pressure fluid is ejected are arranged at intervals of, for example, several millimeters, or 2) a nozzle in which orifice clusters in which minute orifices from which high-pressure fluid is ejected are arranged at intervals and orifice-less sections in which no orifices are drilled are alternately arranged.

[0147] The material and shape of the support, the spacing and shape of the orifices, etc. are appropriately set depending on the desired unevenness and / or pores. The water pressure may be the same as in (2) entanglement treatment.

[0148] (4) Adhesion treatment When at least one of the first and second fiber webs (typically the second fiber web) contains adhesive fibers, the laminated fiber webs are subjected to an adhesive treatment. This causes some of the fibers to adhere to each other, improving the mechanical strength of the nonwoven fabric. The adhesive treatment may be a thermal adhesive treatment, bonding by electron beam irradiation, or ultrasonic welding. In the heat treatment, the adhesive fibers (e.g., low-melting-point components of the composite fiber) melt or soften due to heat during the heat treatment, causing the fibers to adhere to each other. The adhesive treatment is usually performed after the entanglement treatment.

[0149] The heat treatment may be, for example, a hot air processing treatment (also called an air-through processing treatment) in which hot air is blown, a heat roll processing (hot embossing roll processing), or a heat treatment using infrared rays. The heat treatment temperature (for example, the temperature of the hot air) may be a temperature at which a component constituting the adhesive fiber and functioning as an adhesive component softens or melts. For example, the heat treatment temperature may be a temperature equal to or higher than 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 may be 120°C to 133°C. [Example]

[0150] The present disclosure will now be described with reference to examples. The following fibers were prepared for use in this example.

[0151] [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 speed approximately 3.5 seconds, official moisture regain 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 approximately 8 seconds, official moisture regain 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 approximately 3 seconds, official moisture regain 11%

[0152] (Hydrophilized synthetic fiber) Hydrophilic hollow PET: Polyester fiber with a fineness of 2.8 dtex, fiber length of 51 mm, hollow cross section with a hydrophilic surface (hollowness 30%), sedimentation speed of approximately 6 seconds, official moisture regain of 0.7% Hydrophilic PET: Polyester fiber with a fineness of 1.6 dtex, fiber length of 51 mm, surface treated for hydrophilicity, product name: Q201, manufactured by Toray Industries, Inc., sedimentation speed of approximately 3.4 seconds, official moisture regain of 0.6%

[0153] [Hydrophobic fiber] (Water-repellent cellulose fiber) Water-repellent rayon: Viscose rayon with a fineness of 1.7 dtex, fiber length of 40 mm, treated with a non-fluorine water-repellent agent on the surface. Product name: Ecorepellent, manufactured by Daiwabo Rayon Co., Ltd., sedimentation rate of 10 minutes or more, official moisture regain of 12.8%

[0154] (hydrophobic synthetic fiber) PET: Fineness 1.45 dtex, fiber length 38 mm, polyethylene terephthalate fiber, product name: T403, manufactured by Toray Industries, Inc., sedimentation speed 1 minute or more, official moisture regain 0.7% Hollow PET: Polyester fiber with a fineness of 1.45 dtex, fiber length of 51 mm, and hollow cross section (hollowness 30%), product name: T453, manufactured by Toray Industries, Inc., sedimentation rate of 1 minute or more, official moisture regain of 0.7% PET binder: 2.2 dtex fineness, 51 mm fiber length, thermo-adhesive polyethylene terephthalate fiber, product name: T9611, manufactured by Toray Industries, Inc., sedimentation rate of 1 minute or more, official moisture regain of 0.7% PP / PE: Fineness 1.6 dtex, fiber length 51 mm, concentric core-sheath type composite fiber (melting point: approx. 133°C), core: polypropylene, sheath: high-density polyethylene, product name: NBF(H)P, manufactured by Yamatobo Co., Ltd., sedimentation rate 1 minute or more, official moisture content 0%

[0155] [Example 1] (i) Preparation of the first fiber web A mixture of 70% by mass of water-repellent rayon and 30% by mass of 1.7T rayon was carded using a parallel carding machine to a basis weight of approximately 17.5 g / m 2 A first fibrous web was prepared so that the

[0156] (ii) Preparation of the second fiber web A mixture of 40% by mass of hollow PET, 30% by mass of PET binder, and 30% by mass of 3.3T rayon was carded using a parallel carding machine to a basis weight of approximately 17.5 g / m. 2 A second fibrous web was prepared so that:

[0157] (iii) Preparation of nonwoven fabric A first fiber web and a second fiber web were laminated to produce a laminated fiber web. This laminated fiber web was placed on a support (90-mesh plain weave) and transported at a speed of 4 m / min. A water stream at a water pressure of 2.0 MPa was sprayed once onto the surface of the second fiber web. Subsequently, a water stream at a water pressure of 2.5 MPa was sprayed once onto the surface of the first fiber web. In this hydroentanglement treatment, a nozzle with orifices having a hole diameter of 0.12 mm and spaced 0.6 mm apart was used. The distance between the nozzle and the laminated fiber web was 20 mm. Subsequently, the laminated fiber web was dried at 80°C and further heat-treated with hot air at 140°C for 10 seconds to obtain a nonwoven fabric.

[0158] [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 fibers constituting the first and second fiber webs were as shown in Tables 1 to 3.

[0159] However, in Examples 11 and 12 and Comparative Examples 2 and 12, after the entanglement water jet treatment, the nonwoven fabric was placed on a plain weave support manufactured by Daiwabo Co., Ltd. (warp: polyethylene terephthalate monofilament 0.47 mm x 0.76 mm, warp density: 24 mesh / inch, weft: polyethylene terephthalate 0.75 mm, weft density: 17 mesh / inch) and transported at a speed of 4 m / min, while a water jet of 2.0 MPa water pressure was sprayed once onto the surface of the first fibrous web. Subsequently, the nonwoven fabric was dried at 80°C and then heat-treated with hot air at 140°C for 10 seconds to obtain a nonwoven fabric having irregularities (opening rate: 9%). In Comparative Examples 12 and 13, single-layer nonwoven fabrics were prepared, and the heat treatment at 140° C. for 10 seconds was not carried out.

[0160] [evaluation] The evaluation methods were as follows: The 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 using the θ / 2 method as described above.

[0161] (Thickness) The thickness of the nonwoven fabric and each fiber layer was calculated as described above by photographing a cross section of the nonwoven fabric cut in the thickness direction with an SEM and using image analysis software.

[0162] (Liquid absorption speed and wet-back property of 15cc sample) The top sheet was peeled off from a commercially available light incontinence sheet (Whisper (registered trademark) 2-in-1 W-Guard, manufactured by Procter & Gamble Co.). The prepared nonwoven fabric was placed on the remaining ADL and secured around the periphery with packing tape. This was used as a sample for 15 cc. The nonwoven fabric was positioned so that the second fiber layer was in contact with the ADL. A jig with a pouring tube (a two-stage cylinder with a height of 75 mm, an upper inner diameter of 25 mm, and a lower inner diameter of 10 mm) was placed on top of the first fiber layer. 15 cc of saline solution (0.9% by mass) colored blue with a coloring agent (food blue No. 1) was poured into the pouring tube of the jig, and the time until all the saline solution was absorbed was measured. It was also checked whether the saline solution leaked from the gap between the jig and the first fiber layer. If it leaked, the topsheet was unsuitable.

[0163] After 10 minutes had passed since the injection, ten sheets of filter paper (manufactured by Toyo Roshi Kaisha, Ltd., trade name: ADVANTEC (registered trademark) No. 2, 10 cm x 10 cm) whose mass had been measured in advance were stacked and placed at the injection site, and a 1 kg / 10 cm 2 The pressure was applied for 20 seconds. After that, the mass of the 10 filter papers was measured again. The difference in mass of the 10 filter papers before and after the load test was defined as the wetback property (WB).

[0164] (Liquid absorption speed and wet-back property of 100cc sample) A 100 cc sample was obtained in the same manner as above, except that ADL obtained from a commercially available light incontinence sheet (Whisper (registered trademark) thin and absorbent, manufactured by Procter & Gamble) 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 above, except that the amount of physiological saline was 40 cc.

[0165] 15 minutes after measuring the wet-back property (1st WB), 40 cc of saline was again poured into the 100 cc sample, and the second absorption rate and wet-back property (2nd WB) were measured in the same manner as above.

[0166] The thickness, contact angle, liquid absorption rate and wet-back property shown in each table are average values ​​for five samples.

[0167] [Table 1]

[0168] [Table 2]

[0169] [Table 3]

[0170] The nonwoven fabrics of Examples 1 to 21 have an appropriate degree of hydrophilicity in the first and second fiber layers, and therefore have a high liquid absorption rate and excellent wet-back properties.

[0171] The nonwoven fabric of Comparative Example 1 had a first fiber layer made only of water-repellent cellulose fibers, and therefore all samples had a slow liquid absorption rate. Furthermore, when physiological saline was poured into the 100 cc sample, leakage occurred.

[0172] The nonwoven fabrics of Comparative Examples 2 to 4 have a contact angle of less than 80° in the second fiber layer and a high proportion of hydrophilic cellulose fibers in the second fiber layer, and therefore have poor wetback properties, particularly in the 100 cc sample.

[0173] The nonwoven fabric of Comparative Example 5, in which the second fiber layer was formed only from hydrophobic fibers, exhibited a slow liquid absorption rate in all samples. Furthermore, when physiological saline was poured into the 100 cc sample, liquid leakage occurred.

[0174] The nonwoven fabrics of Comparative Examples 6 to 11 have a contact angle of less than 80° in at least one of the first and second fiber layers, and the proportion of hydrophilic cellulose fibers in the second fiber layer is high, so they have poor wetback properties, especially in the 100cc samples.

[0175] The nonwoven fabrics of Comparative Examples 12 and 13 do not have a layer corresponding to the second fiber layer, and therefore Comparative Example 12 has a slow liquid absorption rate, and Comparative Example 13 is poor in both liquid absorption rate and wetback property.

[0176] 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 entanglement of the fibers, the first fiber layer contains, based on the total mass of the first fiber layer, more than 30 mass% and not more than 90 mass% of water-repellent cellulose fibers and 10 mass% or more of hydrophilic fibers; the second fiber layer contains hydrophilic fibers in an amount of 5% by mass or more based on the total mass of the second fiber layer; A nonwoven fabric for absorbent articles, wherein 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 the water penetrates are both 75° or more. (Aspect 2) The nonwoven fabric of aspect 1, wherein the contact angle θ1 and the contact angle θ2 are both 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 relationship: 1≦W2 / W1≦3 The nonwoven fabric of embodiment 1 or 2, which satisfies the above. (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 the above. (Aspect 5) The contact angle θ2, the thickness T1 of the first fiber layer, and the thickness T2 of the second fiber layer are related by the following formula: The nonwoven fabric of any one of Aspects 1 to 4, satisfying TIFF0007752062000007.tif12150. (Aspect 6) Aspects 6. The nonwoven fabric of any one of Aspects 1 to 5, wherein the content of the hydrophilic fibers in the first fiber layer is less than 70% by mass, based on the total mass of the first fiber layer. (Aspect 7) Aspect 7. The nonwoven fabric of any one of aspects 1 to 6, wherein the content of the hydrophilic fibers in the second fiber layer is 90 mass % or less, based on the total mass of the second fiber layer. (Aspect 8) A 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) Aspects 9. The nonwoven fabric of any one of Aspects 1 to 8, wherein the hydrophilic fibers contained in the first fiber layer include hydrophilic cellulose fibers. (Aspect 10) Aspects 1-9. The nonwoven fabric of any one of aspects 1 to 9, wherein the hydrophilic fibers contained in the second fiber layer include hydrophilic cellulose fibers. (Aspect 11) 11. The nonwoven fabric of any one of embodiments 1 to 10, wherein the surface of the first fiber layer has at least one of irregularities and open 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 entanglement of the fibers, the first fiber layer contains, based on the total mass of the first fiber layer, more than 30 mass% but not more than 90 mass% of water-repellent cellulose fibers and 10 mass% or more but less than 70 mass% of hydrophilic fibers; The second fiber layer comprises a hydrophobic fiber, and (a) containing 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 fibrous layer; (b) the second fiber layer contains hydrophilized synthetic fibers in an amount of 40% by mass or more and 90% by mass or less, based on the total mass of the second fiber layer; or (c) A nonwoven fabric for absorbent articles, comprising hydrophilic synthetic fibers in an amount of 30% by mass or more and 90% by mass or less 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 relationship: 1≦W2 / W1≦3 The nonwoven fabric of embodiment 12, which satisfies the above. (Aspect 14) 14. The nonwoven fabric of 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. (Aspect 15) 15. The nonwoven fabric of any one of aspects 12 to 14, wherein the hydrophilic fibers contained in the first fiber layer include hydrophilic cellulose fibers. (Aspect 16) 16. The nonwoven fabric of any one of aspects 12 to 15, wherein the hydrophobic fibers contained in the second fiber layer include hydrophobic synthetic fibers. (Aspect 17) 17. The nonwoven fabric of any one of embodiments 12 to 16, wherein the surface of the first fiber 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 to 17. (Aspect 19) 19. The absorbent article of aspect 18, wherein the nonwoven fabric for absorbent articles is arranged so that the first fibrous layer is the skin contact surface. (Aspect 20) preparing a first fiber web containing more than 30% by mass and not more than 90% by mass of water-repellent cellulosic fibers and 10% by mass or more of hydrophilic fibers, based on the total mass of the first fiber web; Based on the total weight of the hydrophobic fibers and the second fibrous web, (a) Hydrophilic cellulose fibers 、5 Including more than 40% by mass and less than 40% by mass, (b) Hydrophilic synthetic fibers 、4 Contains 0% by mass or more and 90% by mass or less, or (c) Hydrophilic synthetic fibers 、3 preparing the second fibrous web, the second fibrous web comprising from 0% to 90% by mass; overlapping the first fiber web and the second fiber web to form a laminated fiber web; and The laminated fiber web is subjected to an entanglement treatment using a high-pressure fluid stream to entangle the fibers. A method for manufacturing a nonwoven fabric for absorbent articles. [Industrial Applicability]

[0177] The nonwoven fabric of the present disclosure has excellent liquid absorption rate and wetback property, and is therefore useful as a topsheet for various absorbent articles.

Claims

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 entanglement of the fibers, the first fibrous layer contains, based on the total mass of the first fibrous layer, more than 30 mass% but not more than 90 mass% of water-repellent cellulose fibers and 10 mass% or more of hydrophilic fibers; the second fiber layer contains hydrophilic fibers in an amount of 5% by mass or more based on the total mass of the second fiber layer; A nonwoven fabric for absorbent articles, wherein a contact angle θ1 between water and the surface of the first fiber layer and a contact angle θ2 between water and the surface of the second fiber layer before the water permeates are both 75° or more.

2. The nonwoven fabric for absorbent articles according to claim 1 , wherein the contact angle θ1 and the contact angle θ2 are both 120° or less.

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 relationship: 1≦W2 / W1≦3 The nonwoven fabric for absorbent articles according to claim 1 or 2, which satisfies the above.

4. 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 above.

5. The contact angle θ2, the thickness T1 of the first fiber layer, and the thickness T2 of the second fiber layer are related by the following formula: The nonwoven fabric for absorbent articles according to any one of claims 1 to 4, which satisfies the above.

6. The nonwoven fabric for absorbent articles 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 mass% based on the total mass of the first fiber layer.

7. The nonwoven fabric for absorbent articles according to any one of claims 1 to 6, wherein the content of the hydrophilic fibers contained in the second fiber layer is 90 mass% or less, based on the total mass of the second fiber layer.

8. 8. The nonwoven fabric for absorbent articles according to claim 1, wherein the fineness of the hydrophilic fibers contained in the first fiber layer is 0.5 dtex or more and 3 dtex or less.

9. 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 include hydrophilic cellulose fibers.

10. 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 include hydrophilic cellulose fibers.

11. The nonwoven fabric for absorbent articles according to any one of claims 1 to 10, wherein the surface of the first fiber layer has at least one of irregularities and open pores.

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 entanglement of the fibers, the first fiber layer contains, based on the total mass of the first fiber layer, more than 30 mass% but not more than 90 mass% of water-repellent cellulose fibers and 10 mass% or more but less than 70 mass% of hydrophilic fibers; The second fibrous layer comprises hydrophobic fibers, and (a) the second fibrous layer contains 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 fibrous layer; (b) the second fiber layer contains hydrophilized synthetic fibers in an amount of 40% by mass or more and 90% by mass or less, based on the total mass of the second fiber layer; or (c) A nonwoven fabric for absorbent articles, comprising hydrophilic synthetic fibers in an amount of 30% by mass or more and 90% by mass or less, based on the total mass of the second fiber layer.

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 relationship: 1≦W2 / W1≦3 The nonwoven fabric for absorbent articles according to claim 12, which satisfies the above.

14. The nonwoven fabric for absorbent articles according to claim 12 or 13, wherein the fineness of the hydrophilic fibers contained in the first fiber layer is 0.5 dtex or more and 3 dtex or less.

15. 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 include hydrophilic cellulose fibers.

16. The nonwoven fabric for absorbent articles according to any one of claims 12 to 15, wherein the hydrophobic fibers contained in the second fiber layer include hydrophobic synthetic fibers.

17. The nonwoven fabric for absorbent articles according to any one of claims 12 to 16, wherein the surface of the first fiber layer has at least one of irregularities and open pores.

18. 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 so that the first fibrous layer is the skin contact surface.

20. preparing a first fiber web containing more than 30% by mass and not more than 90% by mass of water-repellent cellulosic fibers and 10% by mass or more of hydrophilic fibers, based on the total mass of the first fiber web; Based on the total weight of the hydrophobic fibers and the second fibrous web, (a) Contains hydrophilic cellulose fibers in an amount of 5% by mass or more and 40% by mass or less; (b) containing 40% by mass or more and 90% by mass or less of hydrophilized synthetic fibers, or (c) preparing the second fiber web, the second fiber web comprising 30% by mass or more and 90% by mass or less of hydrophilic synthetic fibers; overlapping the first fiber web and the second fiber web to form a laminated fiber web; and and subjecting the laminated fiber web to an entanglement treatment using a high-pressure fluid stream to entangle the fibers.

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