JP2025139944A - Nonwoven fabric for absorbent articles and manufacturing method thereof - Google Patents

Abstract

The present invention provides a nonwoven fabric for absorbent articles that has excellent liquid absorption properties and is less likely to leave liquid residue.
[Solution] The method for manufacturing a nonwoven fabric for absorbent articles of the present invention includes a C2 adhering step of adhering compound C2 to the surface of a raw nonwoven fabric having compound C1 adhered to the surfaces of its constituent fibers. The water solubility of compound C1 is 0.5 g or more, and the water solubility of compound C2 is 0 g or more and 0.025 g or less. In the C2 adhering step, compound C2 is adhered to the surface of the raw nonwoven fabric in a scattered dot pattern so that the adhesion rate of compound C2 per unit area is 20% or less. In the C2 adhering step, compound C2 is preferably adhered to the surface of the raw nonwoven fabric by inkjet printing.
[Selected Figure] Figure 1

Description

The present invention relates to a nonwoven fabric useful as a component of an absorbent article.

Nonwoven fabrics with a liquid film cleaving agent applied to the surface of their constituent fibers are less likely to leave liquid residue on the surface and have excellent surface dryness after absorbing liquid, making them useful as components that come into contact with the wearer's skin (e.g., topsheets) in absorbent articles such as sanitary napkins and disposable diapers. Liquid film cleaving agents have the effect of inhibiting the formation of liquid films between the constituent fibers of a nonwoven fabric or on the surface of the constituent fibers and/or cleaving any liquid films that have formed, and can exert such effects on human excrement such as menstrual blood and urine.

Patent Documents 1 and 2 describe nonwoven fabrics for absorbent articles that use a liquid film cleaving agent, which have a liquid film cleaving agent-containing portion (compounds C1 and C2) and a non-containing portion on the surface of the nonwoven fabric. Patent Documents 1 and 2 also describe that the water solubility of the liquid film cleaving agent is preferably 0 g or more and 0.025 g or less (claim 10 of Patent Document 1, claim 11 of Patent Document 2), that flexographic printing and inkjet printing can be used to attach the liquid film cleaving agent to the fiber surface (paragraphs [0017] and [0162] of Patent Document 1, and [0015] and [0152] of Patent Document 2), and that it is preferable to localize the liquid film cleaving agent near the fiber entanglement points rather than attaching it evenly over the entire surface of the constituent fibers of the nonwoven fabric (paragraph [0118] of Patent Document 1, and [0102] of Patent Document 2). The nonwoven fabrics described in Patent Documents 1 and 2 are said to be able to reduce the liquid film that forms between the fibers of the nonwoven fabric, thereby achieving a greater level of reduction in residual liquid, while also preventing liquid flow on the surface of the nonwoven fabric.

Japanese Patent Application Laid-Open No. 2017-214694 Japanese Patent Application Laid-Open No. 2017-214695

The nonwoven fabrics described in Patent Documents 1 and 2 are less likely to leave behind liquid and have excellent dryness, but there is room for improvement in preventing liquid residue. That is, while the nonwoven fabrics described in Patent Documents 1 and 2 are able to quickly draw most of the excrement, such as menstrual blood, received on the skin-facing side to the non-skin-facing side, they are unable to draw in all of the excrement, leaving a small amount of excrement remaining on the skin-facing side, which can cause the wearer to feel sticky, leaving room for improvement in terms of dryness.

The objective of the present invention is to provide a nonwoven fabric for absorbent articles that has excellent liquid absorption properties and is less likely to leave liquid residue.

The method for producing a nonwoven fabric for absorbent articles of the present invention includes a C2 adhering step of adhering compound C2 to the surface of a raw material nonwoven fabric having compound C1 adhered to the surfaces of the constituent fibers.
In one embodiment of the method for producing a nonwoven fabric for absorbent articles of the present invention, it is preferable that the water solubility of the compound C1 is 0.5 g or more, and the water solubility of the compound C2 is 0 g or more and 0.025 g or less.
In one embodiment of the method for producing a nonwoven fabric for absorbent articles of the present invention, in the C2 adhering step, it is preferable to adhere the compound C2 to the surface of the raw material nonwoven fabric in a scattered dot pattern so that the adhesion rate of the compound C2 per unit area is 20% or less.

The nonwoven fabric for absorbent articles of the present invention has compound C1 having a water solubility of 0.5 g or more attached to the surface of the constituent fibers of the nonwoven fabric, and compound C2 having a water solubility of 0 g or more and 0.025 g or less attached in a scattered dot pattern to one surface of the nonwoven fabric.
In one embodiment of the nonwoven fabric for absorbent articles of the present invention, it is preferable that the adhesion rate of the compound C2 per unit area on one surface of the nonwoven fabric is 20% or less.
Other features, advantages and embodiments of the present invention are described below.

The present invention provides a nonwoven fabric for absorbent articles that has excellent liquid absorption properties and is less likely to leave liquid residue.

1(a) and 1(b) are plan views each showing a schematic view of the surface of the nonwoven fabric for absorbent articles of the present invention to which compound C2 is attached. 2(a) and 2(b) are enlarged plan views each showing a schematic view of a part of a conventional nonwoven fabric for absorbent articles. FIG. 3 is a plan view schematically showing an enlarged portion of the nonwoven fabric for absorbent articles of the present invention. FIG. 4 is a schematic perspective view of one embodiment of the nonwoven fabric for absorbent articles of the present invention. 5A and 5B are diagrams showing another embodiment of the nonwoven fabric for absorbent articles of the present invention, in which FIG. 5A is a schematic perspective view of the embodiment, and FIG. 5B is a cross-sectional view schematically showing the cross section taken along line II of FIG. 5A. FIG. 6 is a schematic perspective view of still another embodiment of the nonwoven fabric for absorbent articles of the present invention. 7A and 7B are diagrams showing yet another embodiment of the nonwoven fabric for absorbent articles of the present invention, in which FIG. 7A is a schematic perspective view of the embodiment, and FIG. 7B is a cross-sectional view schematically showing the cross section taken along line II-II in FIG. 7A. 8A and 8B are diagrams showing yet another embodiment of the nonwoven fabric for absorbent articles of the present invention, in which FIG. 8A is a schematic perspective view of the embodiment, and FIG. 8B is a schematic cross-sectional view taken along line III-III in FIG. 8A. 9A and 9B are diagrams showing yet another embodiment of the nonwoven fabric for absorbent articles of the present invention, in which FIG. 9A is a schematic perspective view of the embodiment, and FIG. 9B is a schematic cross-sectional view taken along line IV-IV in FIG. 9A.

The manufacturing method for a nonwoven fabric for absorbent articles (hereinafter also simply referred to as "nonwoven fabric") of the present invention includes a step of adhering compound C2 to the surface of a raw nonwoven fabric (C2 adhering step). The raw nonwoven fabric used in this C2 adhering step is a fiber sheet with compound C1 adhered to the surfaces of its constituent fibers, and has one surface located at one end in the thickness direction and the other surface located at the other end in the thickness direction. In the C2 adhering step, compound C2 is adhered in layers to the areas on the surface of the constituent fibers of the raw nonwoven fabric where compound C1 has been adhered.

Compound C1 and compound C2 have different water solubilities, with the water solubility of compound C1 being 0.5 g or more and the water solubility of compound C2 being 0 g or more and 0.025 g or less.
In the present invention, "water solubility" refers to the soluble mass of the substance (compounds C1 and C2) in 100 g of ion-exchanged water, and is measured by the following method. Water solubility is an index of the solubility of the substance in aqueous liquids; the higher the water solubility value, the more easily the substance dissolves in aqueous liquids. The "aqueous liquid" referred to here includes not only water such as ion-exchanged water, but also liquids whose main component is water, such as body fluids (excretions from the human body) such as menstrual blood, urine, feces, and sweat.

<Method for measuring water solubility>
In an environment with an ambient temperature of 25°C and a relative humidity (RH) of 65%, 100 g of ion-exchanged water is stirred with a stirrer while gradually dissolving the test object. The degree of dissolution is visually observed. The water solubility is determined as the amount of dissolution of the test object at the point when the test object no longer dissolves, i.e., when any one of floating, precipitating, precipitation, or cloudiness is visually observed. Specifically, the test object is added in 0.0001 g increments and measured. As a result, if it is observed that even 0.0001 g does not dissolve, it is considered "less than 0.0001 g." If it is observed that 0.0001 g dissolves but 0.0002 g does not dissolve, it is considered "0.0001 g." Note that when the test object is a surfactant, "dissolution" refers to both monodisperse dissolution and micellar dissolution. The amount of dissolution at the point when floating, precipitating, precipitation, or cloudiness is observed is considered the water solubility.

In the method for measuring water solubility, the object to be measured may be a substance attached to the constituent fibers of a nonwoven fabric (hereinafter also referred to as "fiber attachment"). In this case, the fibers are washed with an organic solvent (e.g., hexane, methanol, ethanol, etc.), and the organic solvent (the organic solvent containing the object to be measured) is dried to obtain the fiber attachment. The mass of the fiber attachment thus obtained can be used to calculate the content of the component attached to the constituent fibers in the nonwoven fabric.
If the mass of the fiber attachment obtained is too small to be used for measuring water solubility, the fiber attachment is identified, and if the fiber attachment is commercially available, the commercially available product is procured, or if it is not commercially available, the fiber attachment is synthesized, etc., to ensure the amount required for measurement. The above-mentioned "identification of the fiber attachment (object to be measured)" can be performed, for example, by selecting an appropriate column and solvent according to the constituent components of the fiber attachment, fractionating the constituent components of the fiber attachment by high-performance liquid chromatography, and further performing MS measurement, NMR measurement, elemental analysis, etc. on each fraction. If the fiber attachment contains a polymer compound, the identification of the fiber attachment can be made even easier by combining it with a technique such as gel permeation chromatography (GPC).
Furthermore, when the fiber attachment is attached to a component of the absorbent article (e.g., a topsheet), the component (hereinafter also referred to as the "measurement target component") is removed from the absorbent article and then the fiber attachment is measured according to the following procedure. That is, the adhesive bonding the measurement target component to another component in the absorbent article is weakened by, for example, spraying cold spray on the adhesive, which bonds the two components, and then the measurement target component is carefully peeled off from the other component and removed from the absorbent article. Unless otherwise specified, this method of removing the measurement target component from the absorbent article is applied as appropriate to the measurements described in this specification.

Compound C2, which has a lower water solubility value than compound C1, is less hydrophilic and has lower solubility in aqueous liquids such as body fluids than compound C1. Due to these differences in properties, compound C2 functions as a liquid film cleaving agent in nonwoven fabrics for absorbent articles, whereas compound C1 does not function as a liquid film cleaving agent in nonwoven fabrics for absorbent articles.

As used herein, the term "liquid film splitting agent" refers to an agent that can inhibit the formation of liquid films between fibers or on the surface of fibers in a fiber assembly such as a nonwoven fabric. Such liquid films are typically formed when a liquid, such as a body fluid, comes into contact with a fiber assembly. Liquid film splitting agents typically have the effect of splitting a formed liquid film and the effect of inhibiting the formation of a liquid film, with the former being the primary effect and the latter being the secondary effect. The splitting of a liquid film is achieved by the liquid film splitting agent's action of destabilizing the liquid film by pushing aside part of the liquid film layer. This action of the liquid film splitting agent allows liquid to pass through easily without remaining in the narrow spaces between the fibers of the fiber assembly. Therefore, a fiber assembly containing a liquid film splitting agent has excellent liquid permeability. For example, if the constituent fibers of a nonwoven fabric are made thinner and the distance between the fibers is narrowed, the nonwoven fabric will be soft to the touch, but there is a concern that liquid residue will be more likely to occur. However, by attaching a liquid film cleaving agent to the surface of the constituent fibers of the nonwoven fabric, such concerns can be eliminated, resulting in a nonwoven fabric that is both soft to the touch and reduces liquid residue.

In the C2 attachment step, compound C2 is attached to the surface of the raw nonwoven fabric in a scattered dot pattern so that the attachment rate of compound C2 per unit area (hereinafter also referred to as "C2 attachment area rate") is 20% or less.
The term "scattered pattern" as used herein refers to a pattern in which compound C2 attachment areas (hereinafter also referred to as "C2 attachment areas") are scattered across the surface to be attached (the surface of the raw nonwoven fabric). In the scattered pattern, each of the multiple C2 attachment areas is surrounded by areas to which compound C2 is not attached. In other words, in the C2 attachment step, compound C2 is not attached to the entire area of the surface of the raw nonwoven fabric to which compound C2 is to be attached, i.e., so-called solid application is not performed.
In the C2 attachment step, the compound C2 may be attached to only one surface of the raw material nonwoven fabric, or to both surfaces.

1 shows a specific example of a scattered dot pattern of the compound C2 that can be used in the C2 attachment step, where the symbol C2 in FIG. 1 indicates a C2 attachment portion.
1, the direction indicated by the symbol X (X direction) indicates the same direction as and opposite to the conveyance direction (machine direction: MD) during the production of the nonwoven fabric (during the C2 attachment step), and the direction indicated by the symbol Y (Y direction) indicates the direction perpendicular to the MD (cross machine direction: CD). Typically, the X direction (MD) coincides with the longitudinal direction of the nonwoven fabric, and the Y direction (CD) coincides with the short-side direction (width direction) of the nonwoven fabric.

In the scattered dot pattern shown in FIG. 1(a), each of the multiple C2 attachment portions has an elliptical shape in plan view, i.e., it has a major axis direction and a minor axis direction perpendicular to the major axis direction in plan view. The scattered dot pattern shown in FIG. 1(a) is a so-called staggered pattern, in which multiple rows of multiple C2 attachment portions are intermittently arranged in the major axis direction with the major axis directions aligned, and the rows are spaced apart in the minor axis direction. The "staggered pattern" referred to here refers to an arrangement in which multiple rows of multiple C2 attachment portions are arranged in the minor axis direction (Y direction in FIG. 1(a)), with the C2 attachment portions in each row aligned and equally spaced in the major axis direction (X direction in FIG. 1(a)), and the C2 attachment portions in adjacent rows are offset in the minor axis direction. In other words, when multiple rows of C2 attachment portions arranged at equal intervals in the long axis direction are projected in the short axis direction of the C2 attachment portions, if the projected images of the C2 attachment portions in a particular row are located between the projected images of the C2 attachment portions in another row adjacent to the particular row, the multiple C2 attachment portions can be said to be arranged in a staggered pattern.

The scattered dot pattern shown in FIG. 1(b) differs from the scattered dot pattern shown in FIG. 1(a) in that the C2 attachment portions are arranged in a grid pattern rather than a staggered pattern. The term "grid pattern" as used here refers to an arrangement in which multiple rows of C2 attachment portions, each with their major axis aligned and equally spaced in the major axis direction (X direction in FIG. 1(b)), are arranged in the minor axis direction of the C2 attachment portions (Y direction in FIG. 1(b)), and the C2 attachment portions are not shifted between two adjacent rows in the minor axis direction (i.e., the C2 attachment portions are adjacent to each other in one of two adjacent rows). In other words, when multiple rows of C2 attachment portions, each with a major axis aligned and equally spaced in the major axis direction, are projected in the minor axis direction of the C2 attachment portions, if the projected images of the C2 attachment portions in a particular row are not interspersed with the projected images of the C2 attachment portions in another row adjacent to the particular row, the multiple C2 attachment portions can be said to be arranged in a grid pattern.

In the nonwoven fabric of the present invention, the arrangement pattern of the C2 attachment portions is not limited to that shown in Figure 1, and various scattered patterns can be used, provided that they do not impair the desired effects of the present invention. For example, the planar shape of the C2 attachment portions is not limited to a shape (anisotropic shape) in which the diameter length differs in the X direction (MD) and the Y direction (CD), such as the ellipse shown in Figure 2, but may also be a shape (isotropic shape) in which the diameter length is the same in the X direction (MD) and the Y direction (CD). Specific examples of the anisotropic shape include a rectangle and a diamond, in addition to an ellipse. Specific examples of the isotropic shape include a circle and a square.

The gist of the method for producing a nonwoven fabric of the present invention has been described above, and its main features include the following features A and B. Because the method for producing a nonwoven fabric of the present invention has the following features A and B, the nonwoven fabric obtained by implementing the method has excellent liquid absorption properties and is less likely to leave liquid residue, and when used as a component of an absorbent article (for example, a topsheet), it exhibits high dryness and is less likely to cause stickiness to the wearer after excretion of menstrual blood or the like, which can greatly contribute to improving the wearing comfort of the absorbent article.
Feature A: A compound C1 having a relatively high water solubility is adhered to the surface of the constituent fibers of a raw nonwoven fabric in advance, and then a compound C2 having a relatively low water solubility is adhered to the surface of the raw nonwoven fabric.
Feature B: The treatment liquid is applied to the surface of the raw nonwoven fabric in a scattered pattern so that the C2 application area ratio is 20% or less.

As a result of various studies on nonwoven fabrics using a liquid film splitting agent, the present inventors have found that minimizing the presence of the liquid film splitting agent at the fiber entanglement points of the nonwoven fabric (presence of the liquid film splitting agent in areas other than the fiber entanglement points of the nonwoven fabric) is effective in improving the effect of preventing liquid residue. The "fiber entanglement points" referred to here refer to overlapping portions of multiple fibers, and include those in which multiple fibers are simply in contact without being integrated, and those in which multiple fibers are fused and integrated.
Figure 2 shows an example of a conventional nonwoven fabric for absorbent articles that uses a liquid film cleaving agent. Figure 2(a) shows a nonwoven fabric in which the liquid film cleaving agent was applied using flexographic printing, and Figure 2(b) shows a nonwoven fabric in which the liquid film cleaving agent was applied using inkjet printing. Although the two nonwoven fabrics differ somewhat in the amount of liquid film cleaving agent C2 applied and the size of the droplets of the liquid film cleaving agent C2 due to the difference in the method of application of the liquid film cleaving agent C2, they share in common the fact that the liquid film cleaving agent C2 is present at many of the countless fiber entanglement points Fi in the nonwoven fabric, and that the liquid film cleaving agent C2 present at the fiber entanglement points Fi is difficult to separate from the fiber entanglement points Fi due to the capillary force of the fibers F.
In contrast, in a nonwoven fabric produced by the production method of the present invention (hereinafter also simply referred to as "the nonwoven fabric of the present invention"), the presence of the liquid film splitting agent C2 at the fiber entanglement points is reduced compared to a conventional nonwoven fabric as shown in Figure 2, and when any part of the nonwoven fabric is observed, it is often possible to confirm that the liquid film splitting agent C2 is not present at the fiber entanglement points Fi, as shown in Figure 3. Specifically, for example, in the nonwoven fabric of the present invention, compound C2 may not be present at 50% or more of all the fiber entanglement points present in the nonwoven fabric.
It is presumed that the small amount of liquid film splitting agent present at the fiber entanglement points in the nonwoven fabric of the present invention (the large amount of liquid film splitting agent present in areas other than the fiber entanglement points) is closely related to the excellent liquid attraction properties of the nonwoven fabric. That is, as mentioned above, the liquid film splitting agent splits the liquid film by destabilizing it by pushing aside part of the liquid film layer, and for this to happen, the liquid film splitting agent present as a liquid on the surface of the constituent fibers of the nonwoven fabric must be in a state where it can leave the constituent fibers and migrate into the liquid film. In this regard, the liquid film splitting agent present at the fiber entanglement points of the nonwoven fabric is difficult to leave its location due to the strong capillary force of the fiber entanglement points, while the liquid film splitting agent present in areas other than the fiber entanglement points of the nonwoven fabric has a relatively high degree of freedom of movement and is therefore more likely to leave its location and migrate into the liquid film. Therefore, the nonwoven fabric of the present invention, which has a relatively large amount of liquid film splitting agent present in areas other than the fiber entanglement points, can fully exhibit the effect of the liquid film splitting agent and has a superior effect of preventing liquid residue compared to conventional nonwoven fabrics using a liquid film splitting agent as shown in Figure 2.

The feature A is particularly important in realizing a state in which the compound C2, which is a liquid film splitting agent, is present in areas other than the fiber entanglement points Fi, as shown in Figure 3. The reason for this will be explained below.
When compound C2 is applied by flexographic printing, inkjet printing, or the like to a raw nonwoven fabric that does not have compound C1 attached to the surfaces of its constituent fibers, as in conventional nonwoven fabric manufacturing methods, even if the initial attachment position of compound C2 is a location other than the fiber entanglement points, compound C2 tends to migrate to the fiber entanglement points due to the capillary forces of the constituent fibers. When the nonwoven fabric is in use, compound C2 may be present at the fiber entanglement points Fi, as shown in Figure 2 . In contrast, the nonwoven fabric manufacturing method of the present invention has Feature A, in which compound C2 is attached to compound C1 already attached to the surfaces of the constituent fibers of the raw nonwoven fabric. Therefore, even when capillary forces of the constituent fibers act, compound C2 tends to remain at its initial attachment position. This is because there is a large polarity difference between compound C1 and compound C2, corresponding to the large difference in their water solubilities. This makes it difficult for liquid compound C2 to move or spread on compound C1 attached to the surfaces of the constituent fibers of the nonwoven fabric. In an example of a nonwoven fabric of the present invention shown in Figure 3, compound C1 (the areas colored gray in Figure 3) is adhered to the entire surface of all fibers F constituting the nonwoven fabric, i.e., compound C1 is adhered to the entire surface of all fibers F constituting the raw nonwoven fabric during production of the nonwoven fabric, so that no matter where compound C2 is adhered to on the surface of fibers F in the subsequent C2 adhesion step, it is difficult for compound C2 to move from its initial adhesion position. Therefore, according to the method for producing a nonwoven fabric of the present invention having characteristic A, compound C2 is likely to be present in sites other than fiber entanglement points in the nonwoven fabric.

Furthermore, the nonwoven fabric manufacturing method of the present invention employs Feature A, directing the attachment position of Compound C2 to areas of the raw nonwoven fabric other than fiber entanglement points, where the functional effects of Compound C2 are likely to be exerted. This eliminates the need to attach a large amount of Compound C2 to the raw nonwoven fabric. Feature B is the optimal attachment pattern for Compound C2, assuming the adoption of Feature A, and the intended effects of the present invention are only achieved by employing both Features A and B.

From the viewpoint of ensuring the desired effects of the present invention, the water solubility of compound C1 is preferably 0.7 g or more, more preferably 1.0 g or more, and preferably 70 g or less, more preferably 50 g or less. Furthermore, the water solubility of compound C2 is preferably 0.001 g or more, more preferably 0.002 g or more, and preferably 0.020 g or less, more preferably 0.010 g or less.

When the arrangement of the attachment portions of compound C2 (C2 attachment portions) in the nonwoven fabric to be produced is a staggered arrangement as shown in FIG. 1( a) or a lattice arrangement as shown in FIG. 1( b), from the viewpoint of more reliably achieving the desired effects of the present invention, it is preferable to attach compound C2 in the C2 attachment step so that the dimensional ratios of each portion in the nonwoven fabric are as follows:
The ratio (S2/S1) of the length S2 of a C2 attachment portion in the minor axis direction (Y direction) to the spacing S1 between adjacent C2 attachment portions in the minor axis direction (Y direction) is preferably 0.6 or less, more preferably 0.4 or less. On the other hand, the lower limit of S2/S1 is preferably 0.01 or more, more preferably 0.02 or more, from the viewpoint of reliably exerting the liquid membrane splitting effect of compound C2.
The ratio (S4/S3) of the longitudinal length S4 of a C2 attachment portion to the spacing S3 between adjacent C2 attachment portions in the longitudinal direction (X direction) is preferably 0.6 or less, more preferably 0.4 or less. On the other hand, the lower limit of S4/S3 is preferably 0.01 or more, more preferably 0.02 or more, from the viewpoint of ensuring that the liquid membrane splitting effect of compound C2 is exerted.

The distance S1 between the C2 attachment portions in the minor axis direction is preferably 1 mm or more, more preferably 2 mm or more, and is preferably 30 mm or less, more preferably 20 mm or less.
The length S2 of the C2 attachment portion in the minor axis direction is preferably 0.01 mm or more, more preferably 0.05 mm or more, and is preferably 10 mm or less, more preferably 7 mm or less.
The distance S3 between the C2 attachment portions in the longitudinal direction is preferably 1 mm or more, more preferably 2 mm or more, and is preferably 30 mm or less, more preferably 20 mm or less.
The length S4 of the C2 attachment portion in the major axis direction is preferably 0.01 mm or more, more preferably 0.05 mm or more, and is preferably 10 mm or less, more preferably 7 mm or less.

To ensure that the desired effects of the present invention are achieved more reliably, the C2 adhesion area ratio in the C2 adhesion process is preferably 0.01% or more, more preferably 0.03% or more, and preferably 18% or less, more preferably 15% or less. The C2 adhesion area ratio can be measured by the following method.

<Method for measuring C2 adhesion area ratio>
For the compound C2-adhered surface of the nonwoven fabric to be measured, the total area of the compound C2-adhered portions (C2-adhered portions) present in the reference region is measured, and the ratio of the measured value of the total area to the area of the region is calculated, and this calculated value is the C2-adhered area ratio of the nonwoven fabric to be measured.
The method for measuring the C2 attachment area ratio will be specifically described below using the nonwoven fabric shown in Figure 1 as an example. First, the spacing S1 between adjacent C2 attachment areas in the Y direction (the direction of the minor axis of the C2 attachment areas), the length S2 of the C2 attachment areas in the Y direction, the spacing S3 between adjacent C2 attachment areas in the X direction (the direction of the major axis of the C2 attachment areas), and the length S4 of the C2 attachment areas in the X direction are measured (dimension measurement step). These measurements are performed at 10 random locations on the nonwoven fabric to be measured, and the average values of these measurements are designated as S1, S2, S3, and S4 for the nonwoven fabric. The target C2 attachment area ratio is then calculated using the following formula:
C2 adhesion area ratio (%) = [(S2×S4)/{(S1+S2)×(S3+S4)}]×100
The dimension measurement of each portion of the nonwoven fabric in the dimension measurement step can be performed using a ruler. Furthermore, from the viewpoint of increasing the visibility of the C2-attached portion and improving the accuracy of the dimension measurement, a fluorescent paint may be contained in the C2-attached portion. The C2-attached portion containing the fluorescent paint can be obtained by adding the fluorescent paint to a C2-containing liquid, which will be described later and is used to attach compound C2 to the raw nonwoven fabric, and then applying the C2-containing liquid to the raw nonwoven fabric.

In the C2 application step, a liquid containing compound C2 (hereinafter also referred to as "C2-containing liquid") is applied to the surface of the raw nonwoven fabric. The C2-containing liquid may be any liquid that is liquid at room temperature and normal pressure (for example, an environment with an ambient temperature of 25°C and 1 atmosphere) and that can be used in a known liquid application method such as inkjet printing. The C2-containing liquid may contain only compound C2, or may contain other components in addition to compound C2.
Examples of components other than compound C2 that can be contained in the C2-containing liquid include a liquid medium that dissolves or disperses the components such as compound C2, as well as surfactants and antistatic agents.
Examples of the liquid medium include water and organic solvents, and specific examples of the organic solvent include ethanol, methanol, acetone, and hexane. In the present invention, the liquid medium can be used alone or in combination of two or more.
The surfactant is useful for making Compound C2, which has a low water solubility, easier to handle in known printing methods. Examples of the surfactant include alkyl phosphate esters, fatty acid amides, alkyl betaines, and sodium alkyl sulfosuccinates, and these surfactants can be used alone or in combination of two or more.
When the C2-containing liquid contains components other than compound C2, the content of compound C2 in the C2-containing liquid can be adjusted appropriately depending on the method of applying the C2-containing liquid, the type of nonwoven fabric to which it is to be applied, etc., and is not particularly limited, but is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 1 mass% or more, even more preferably 5 mass% or more, even more preferably 10 mass% or more, and preferably 80 mass% or less, more preferably 60 mass% or less, and even more preferably 40 mass% or less, relative to the total mass of the C2-containing liquid.

The method for applying the C2-containing liquid to the surface of the raw nonwoven fabric is not particularly limited, provided that it does not impair Feature B, and any known method that can be used to apply a liquid to a nonwoven fabric can be used. A preferred method for applying the C2-containing liquid is inkjet printing. As is well known, inkjet printing is a method in which tiny ink droplets are sprayed from the nozzles of an inkjet head onto a substrate, and in the C2 application process, a C2-containing liquid is used instead of ink. Inkjet printing methods include valve printing, bubble jet (thermal jet) printing, and piezo printing, but the type of inkjet printing method is not particularly limited in the present invention.

From the viewpoint of improving the liquid absorption, the amount of compound C2 (C2-containing liquid) adhered per unit area (basis weight) to the raw material nonwoven fabric is, in terms of solid content, preferably 0.01 g/ ^m2 or more, more preferably 0.05 g/ ^m2 or more, even more preferably 0.1 g/ ^m2 or more, still more preferably 0.3 g/ ^m2 or more, and preferably 20 g/m2 or ^less , more preferably 15 g/m2 or ^less , even more preferably 10 g/m2 or ^less , still more preferably 5 g/m2 or ^less , and still more preferably 4 g/m2 ^{or less} .

From the viewpoint of improving the liquid drawability, the amount of compound C2 adhered per unit area (basis weight) in the adhered portion of the C2-containing liquid is, in terms of solid content, preferably 10 g/ ^m2 or more, more preferably 20 g/m2 or ^more , even more preferably 30 g/ ^m2 or more, and preferably 2500 g/m2 or ^less , more preferably 2000 g/m2 or ^less , even more preferably 1500 g/m2 or ^less , even more preferably 1000 g/m2 or ^less , even more preferably 500 g/m2 or ^less , even more preferably 400 g/ ^m2 or less, even more preferably 300 g/ ^m2 or less, and even more preferably 150 g/ ^m2 or less.

To further explain the C2 attachment process, the raw nonwoven fabric used in the C2 attachment process is a nonwoven fabric having compound C1 attached to the surfaces of its constituent fibers. Such a nonwoven fabric pretreated with compound C1 can be obtained by attaching compound C1 to an untreated nonwoven fabric to which compounds C1 and C2 are not attached. While the attachment method is not particularly limited, as mentioned above, one of the primary purposes of compound C1 is to limit the movement of compound C2 attached to the fiber surfaces after attachment, thereby reducing the possibility of compound C2 being present at fiber entanglement points. To reliably achieve this purpose, it is preferable that compound C1 be attached to the entire surface of the constituent fibers of the raw nonwoven fabric, as shown in Figure 3, before the C2-containing liquid is attached. A preferred method of attaching compound C1 to the raw nonwoven fabric is one that can reliably achieve this state of compound C1 attachment. Specific examples of such preferred adhesion methods include a dipping method in which the raw nonwoven fabric is immersed in a liquid containing compound C1 (hereinafter also referred to as a "C1-containing liquid"), and a method in which the C1-containing liquid is applied using various application devices (slot coater, gravure printing machine, flexographic printing machine, etc.).

After compound C1 (C1-containing liquid) has been applied to the surface of the constituent fibers of the raw nonwoven fabric, the raw nonwoven fabric may be dried, if necessary. Such drying of the raw nonwoven fabric is typically carried out using a known dryer, such as a hot air blower, so that the temperature of the raw nonwoven fabric during drying is lower than the melting point of the resin forming the constituent fibers.

The object to which the C1-containing liquid is applied does not have to be a nonwoven fabric; it can also be fibers, which are the raw material for nonwoven fabric. That is, after the C1-containing liquid is applied to the surface of fibers, raw nonwoven fabric can be manufactured using the fibers in accordance with conventional methods. Furthermore, nonwoven fabric is usually manufactured by forming a web from fibers and then converting the web into nonwoven fabric. However, the C1-containing liquid can also be applied to the web and then the web can be converted into nonwoven fabric.

The C1-containing liquid may be any liquid that contains compound C1, is liquid at room temperature and pressure, and can be used in a known liquid application method such as a dipping method, and may contain only compound C1, or may contain other components in addition to compound C1.
When the C1-containing liquid contains components other than compound C1, the content of compound C1 in the C1-containing liquid can be adjusted appropriately depending on the method of applying the C1-containing liquid, the type of nonwoven fabric or fiber to which the liquid is to be applied, etc., and is not particularly limited, but is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and preferably 80 mass% or less, more preferably 60 mass% or less, even more preferably 40 mass% or less, even more preferably 20 mass% or less, even more preferably 10 mass% or less, and even more preferably 5 mass% or less, relative to the total mass of the C1-containing liquid. As the other components, the same components as those other than compound C2 that can be used in the C2-containing liquid (liquid medium, surfactant, antistatic agent, etc.) can be used.

The amount of compound C1 (C1-containing liquid) adhered per unit area (basis weight) to the raw nonwoven fabric is, in terms of solid content, preferably 0.01 g/ ^m2 or more, more preferably 0.03 g/ ^m2 or more, even more preferably 0.05 g/ ^m2 or more, still more preferably 0.1 g/ ^m2 or more, and preferably 5 g/ ^m2 or less, more preferably 2 g/ ^m2 or less.

As mentioned above, the main role of compound C1 is to restrict the movement of compound C2 on the fiber surface and reduce the possibility of compound C2 being present at fiber entanglement points. Therefore, to ensure that compound C1 fulfills this role, the ratio of the mass per unit area (basis weight) of compound C1 relative to the raw nonwoven fabric to that of compound C2 relative to the raw nonwoven fabric (basis weight of compound C2/basis weight of compound C1) is preferably 0.5 or more, more preferably 1 or more, even more preferably 3 or more, and preferably 300 or less, more preferably 150 or less, even more preferably 100 or less, even more preferably 70 or less, even more preferably 50 or less, even more preferably 30 or less, even more preferably 20 or less, and even more preferably 10 or less.

The method for producing a nonwoven fabric of the present invention may include, prior to the C2 adhering step, a step of producing a raw nonwoven fabric having compound C1 adhered to the surfaces of the constituent fibers, in other words, a step of adhering compound C1 (C1-containing liquid) to the surfaces of the constituent fibers of the raw nonwoven fabric (C1 adhering step).

The nonwoven fabric manufacturing method of the present invention may include a step of drying the raw nonwoven fabric to which the C2-containing liquid has been attached (post-C2 attachment drying step) after the C2 attachment step. The post-C2 attachment drying step is typically carried out using a known dryer such as a hot air blower, so that the temperature of the raw nonwoven fabric during this step is lower than the melting point of the resin forming the constituent fibers.

As the compound C1, a compound to which a known liquid application method such as a dipping method can be applied can be used, provided that the compound C1 has a water solubility of 0.5 g or more. In the present invention, one type of compound C1 may be used, or two or more types of compounds C1 may be used in combination.
Preferred examples of the compound C1 include phosphate ester-type anionic surfactants. Specific examples of the phosphate ester-type anionic surfactants include mono- or di-alkyl ether phosphate esters and mono- or di-alkyl phosphate esters.

Specific examples of mono- or di-alkyl ether phosphate esters (compound C1) include those with saturated carbon chains, such as mono- or di-polyoxyalkylene stearyl ether phosphate esters, mono- or di-polyoxyalkylene myristyl ether phosphate esters, mono- or di-polyoxyalkylene lauryl ether phosphate esters, and mono- or di-polyoxyalkylene palmityl ether phosphate esters; those with unsaturated carbon chains, such as mono- or di-polyoxyalkylene oleyl ether phosphate esters and mono- or di-polyoxyalkylene palmitoleic ether phosphate esters; and those with side chains on the saturated or unsaturated carbon chains. Preferred are fully or partially neutralized salts of mono- or di-polyoxyalkylene alkyl ether phosphate esters with carbon chains of 16 to 18. Examples of polyoxyalkylenes include polyoxyethylene, polyoxypropylene, polyoxybutylene, and copolymers of these constituent monomers. Examples of salts of mono- or di-alkyl ether phosphate esters include alkali metals such as sodium and potassium; ammonia; and various amines.

Specific examples of mono- or di-alkyl phosphate esters (compound C1) include those with saturated carbon chains such as mono- or distearyl phosphate ester, mono- or dimyristyl phosphate ester, mono- or dilauryl phosphate ester, and mono- or dipalmityl phosphate ester; those with unsaturated carbon chains such as mono- or dioleyl phosphate ester and mono- or dipalmitoleyl phosphate ester; and those with side chains on the saturated or unsaturated carbon chains. Preferable salts are fully or partially neutralized salts of mono- or di-alkyl phosphate esters with carbon chains of 16 to 18. Examples of salts of mono- or di-alkyl phosphate esters include alkali metals such as sodium and potassium; ammonia; and various amines.

As the compound C2, any agent that can function as a liquid membrane cleaving agent can be used without any particular limitation, provided that the water solubility is 0 g or more and 0.025 g or less.
Liquid membrane cleaving agents can be classified into silicone compounds and non-silicone compounds. In the present invention, one or more compounds selected from the group consisting of silicone compounds and non-silicone compounds can be used as compound C2.
Specific examples of the silicone compound (liquid membrane cleaving agent) include dimethicone, dimethiconol, and cyclomethicone; amino-modified silicone; and polyether-modified silicone.
Specific examples of the non-silicone compound (liquid membrane cleaving agent) include polyether compounds selected from polyalkylene glycols and polyoxyalkylene alkyl ethers; hydrocarbon compounds having 5 to 18 carbon atoms; saturated fatty acids or derivatives thereof having 9 or less carbon atoms; and unsaturated fatty acids or derivatives thereof having 22 or less carbon atoms.
As the compound C2, the liquid membrane cleaving agents described in paragraphs [0038] to [0054] and [0057] to [0109] of Patent Document 1 can also be used.

In the nonwoven fabric manufacturing method of the present invention, the type of raw material nonwoven fabric is not particularly limited, and nonwoven fabrics manufactured by various manufacturing methods can be used. Specific examples of raw material nonwoven fabrics include air-through nonwoven fabrics, spunbond nonwoven fabrics, spunlace nonwoven fabrics, needle-punched nonwoven fabrics, and chemical-bonded nonwoven fabrics. From the standpoint of feel, the raw material nonwoven fabric is preferably air-through nonwoven fabrics or spunbonded nonwoven fabrics. In other words, the nonwoven fabric that is the target of manufacturing in the present invention preferably includes air-through nonwoven fabrics or spunbonded nonwoven fabrics.

The constituent fibers of the raw nonwoven fabric can be any fiber that can be used as a constituent fiber of a nonwoven fabric member in an absorbent article, without any particular limitation. Examples include heat-fusible core-sheath composite fibers, heat-extensible fibers, non-heat-extensible fibers, heat-shrinkable fibers, non-heat-shrinkable fibers, three-dimensionally crimped fibers, latent crimped fibers, and hollow fibers. The nonwoven fabric of the present invention may contain only one type of fiber as a constituent fiber, or may contain two or more types of fibers.
The raw material nonwoven fabric is typically mainly composed of thermoplastic fibers. Thermoplastic fibers are fibers containing a thermoplastic resin. Examples of thermoplastic resins contained in thermoplastic fibers include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; poly(meth)acrylic acid alkyl esters, polyvinyl chloride, and polyvinylidene chloride. The thermoplastic fibers may be composite fibers such as core-sheath or side-by-side types, split fibers, modified cross-section fibers, heat-shrinkable fibers, etc. The composite fibers may be composed of multiple resin components.

The raw material nonwoven fabric may be a flat nonwoven fabric having substantially no irregularities on the surface, or may be an irregular nonwoven fabric having an irregular surface on at least one side composed of convex and concave portions. When an irregular nonwoven fabric is used as the raw material nonwoven fabric, the target to which compound C2 is attached can be the irregular surface.
4 to 9 show specific examples of concavo-convex nonwoven fabrics that can be used as raw material nonwoven fabrics in the nonwoven fabric manufacturing method of the present invention.

The nonwoven fabric 10a shown in Figure 4 has a first surface F1 and a second surface F2 located opposite the first surface F1. The first surface F1 and the second surface F2 are surfaces perpendicular to the thickness direction Z of the nonwoven fabric 10a. The nonwoven fabric 10a also has two mutually perpendicular directions: the X direction and the Y direction. The X direction is the conveying direction (machine direction: hereinafter also referred to as "MD") of the nonwoven fabric 10a during production, and the Y direction is the direction perpendicular to the MD (cross machine direction: hereinafter also referred to as "CD"). Typically, the X direction (MD) coincides with the longitudinal direction of the nonwoven fabric 10a, and the Y direction (CD) coincides with the short-side direction (width direction) of the nonwoven fabric 10a.

Nonwoven fabric 10a has a laminated structure of a first fiber layer 11 and a second fiber layer 12, with the two layers 11 and 12 adjacent to each other. The first fiber layer 11 forms the first side F1 of nonwoven fabric 10a, and the second fiber layer 12 forms the second side F2 of nonwoven fabric 10a. In nonwoven fabric 10a, the laminated first fiber layer 11 and second fiber layer 12 are bonded to each other at multiple joints 13, and the first fiber layer 11 protrudes away from the second fiber layer 12 at locations other than the joints 13 to form convex portions 14. This gives each convex portion 14 a hollow structure. The hollow structure is closed, not open. The joints 13 form concave portions 15. The convex portions 14 and concave portions 15 are scattered across the plane of nonwoven fabric 10a. More specifically, multiple rows of protrusions 14 and recesses 15 are arranged intermittently in the X direction (Y direction), and the protrusions 14 and recesses 15 are arranged in the Y direction (X direction) so that the protrusions 14 (recesses 15) are not adjacent to each other between adjacent rows of protrusions 14 (recesses 15) in the Y direction (X direction).

The nonwoven fabric 10a can be manufactured using a method similar to the composite sheet manufacturing method described in JP 2015-112343 A, for example. Specifically, the nonwoven fabric 10a can be manufactured by laminating the unevenly deformed first fiber layer 11 onto the second fiber layer 12 to obtain a laminate, and then embossing the laminate to bond the two fiber layers 11, 12. The first fiber layer 11 can be deformed into an uneven shape by feeding it between a pair of rolls whose peripheral surfaces interlock with each other.

The following describes the nonwoven fabrics 10b to 10f shown in Figures 5 to 9, with differences from the nonwoven fabric 10a described above. Similar components are given the same reference numerals and will not be described again. For components not specifically described for nonwoven fabrics 10b to 10f, the same description for nonwoven fabric 10a applies as appropriate.

The nonwoven fabric 10b shown in Figure 5 has an uneven shape on both the first surface F1 and the second surface F2, and the uneven shape on the first surface F1 corresponds to the uneven shape on the second surface F2. More specifically, the nonwoven fabric 10b has an uneven shape on the first surface F1 consisting of convex portions 14 and concave portions 15, and an uneven shape on the second surface F2 consisting of back-side convex portions 17 and back-side concave portions 16. The convex portions 14 on the first surface F1 protrude toward the first surface F1 and have spaces open to the second surface F2. The concave portions 15 on the first surface F1 protrude toward the second surface F2 and have spaces open to the first surface F1. The second surface F2 side of the concave portions 15 on the first surface F1 forms back-side convex portions 17 protruding toward the second surface F2, and the second surface F2 side of the convex portions 14 on the first surface F1 forms back-side concave portions 16 protruding toward the first surface F1.
In the nonwoven fabric 10b, as shown in FIG. 5(b), the laminated first fiber layer 11 and second fiber layer 12 are integrated to form the unevenness on the first surface F1 and the unevenness on the second surface F2.

The laminated nonwoven fabric 10b can be manufactured, for example, by a method similar to the manufacturing method of the laminated nonwoven fabric described in JP 2013-124428 A. Specifically, a web containing heat-fusible fibers that will become the first fiber layer 11 is placed on a breathable support having an uneven surface. Hot air (hereinafter also referred to as "first hot air") is blown onto the web from the side opposite the support, shaping the web to conform to the uneven surface of the support. Next, a second hot air having a higher temperature than the first hot air is blown onto the shaped web above the support, fusing the fibers of the web together and fixing the shaped shape, thereby producing the unevenly shaped first fiber layer 11. Next, a web containing heat-fusible fibers that will become the second fiber layer 12 is laminated onto the first fiber layer 11, and hot air is blown onto the web to heat-fuse the fibers of the web while conforming to the uneven shape of the first fiber layer 11, thereby producing a nonwoven fabric 10b in which the first fiber layer 11 and second fiber layer 12 are bonded together.

The nonwoven fabric 10c shown in Figure 6 has a ridge-furrow shape on the first surface F1 side. More specifically, the nonwoven fabric 10c has protruding ribs 14a and recessed ribs 15a that are thinner than the protruding ribs 14a. The protruding ribs 14a and the recessed ribs 15a each extend in one direction (the Y direction in Figure 6), and the protruding ribs 14a and the recessed ribs 15a are arranged alternately in a direction perpendicular to the extending direction (the X direction in Figure 6). As the protruding ribs 14a become convex portions and the recessed ribs 15a become concave portions, the nonwoven fabric 10c has an uneven shape on the first surface F1, while the second surface F2 is flat.

The nonwoven fabric 10d shown in Figure 7 has ridge-furrow shapes on both the first surface F1 and the second surface F2, with the ridge-furrow shape on the first surface F1 corresponding to the ridge-furrow shape on the second surface F2. More specifically, the nonwoven fabric 10d has ridges 14a and grooves 15a on the first surface F1, and rear ridges 17a and rear grooves 16a on the second surface F2. The ridges 14a on the first surface F1 protrude toward the first surface F1 and have spaces open toward the second surface F2. The grooves 15a on the first surface F1 protrude toward the second surface F2 and have spaces open toward the first surface F1. The second surface F2 side of the groove portion 15a of the first surface F1 is a back side convex streak portion 17a that protrudes toward the second surface F2 side, and the second surface F2 side of the convex streak portion 14a of the first surface F1 is a back side concave streak portion 16a that protrudes toward the first surface F1 side.
The convex streaks 14a and the concave streaks 15a, as well as the back-side convex streaks 17a and the back-side concave streaks 16a, each extend in one direction (the Y direction in FIG. 7(a)). On the first surface F1, the convex streaks 14a and the concave streaks 15a are alternately arranged in a direction perpendicular to the extending direction of the convex streaks 14a and the concave streaks 15a (the X direction in FIG. 7(a)). Similarly, on the second surface F2, the back-side convex streaks 17a and the back-side concave streaks 16a are alternately arranged in a direction perpendicular to the extending direction of the convex streaks 17a and the concave streaks 16a (the X direction in FIG. 7(a)).
As shown in FIG. 7(b), the nonwoven fabric 10d has a first surface F1 and a second surface F2 formed by stacking the first fiber layer 11 and the second fiber layer 12 together.

The nonwoven fabric 10e shown in Figure 8 has, on its first surface F1, multiple protruding portions 14 and linear recessed portions 15 surrounding them. The recessed portions 15 are arranged in a lattice pattern, with protruding portions 14 formed in each area defined by the lattice-shaped recessed portions 15. Also, as shown in Figure 8(b), in nonwoven fabric 10e, the protruding portions 14 have a solid structure filled with the constituent fibers of the first fiber layer 11 and the second fiber layer 12, with the first fiber layer 11 mainly protruding toward the first surface F1. Furthermore, the recessed portions 15 include junctions where the constituent fibers of the first fiber layer 11 and the second fiber layer 12 are consolidated and joined.

The nonwoven fabric 10f shown in Figure 9 has a plurality of convex portions 14 and concave portions 15 on the first surface F1, with the convex portions 14 arranged in a staggered pattern. The convex portions 14 have a generally circular shape in plan view, with the apex of each convex portion 14 located at the center of the convex portion 14 in plan view. Furthermore, as shown in Figure 9(b), in the nonwoven fabric 10f, the convex portions 14 have a hollow structure in which a closed hollow space is formed between the first fiber layer 11 and the second fiber layer 12.

The raw nonwoven fabric may have a single-layer structure or a laminated structure in which multiple fiber layers are stacked. While the nonwoven fabrics 10a to 10f described above were all uneven nonwoven fabrics with a laminated structure (a two-layer structure in the illustrated embodiment), the nonwoven fabric manufacturing method of the present invention can also use an uneven nonwoven fabric with a single-layer structure as the raw nonwoven fabric. A specific example of an uneven nonwoven fabric with a single-layer structure is a form in which a single fiber layer is used instead of the first fiber layer 11 and second fiber layer 12 in nonwoven fabrics 10b to 10e (nonwoven fabrics without a closed hollow structure).

The present invention includes a nonwoven fabric for absorbent articles (hereinafter also simply referred to as "nonwoven fabric"). The nonwoven fabric of the present invention can be produced by the above-mentioned method for producing the nonwoven fabric of the present invention.
The following describes the nonwoven fabric of the present invention in terms of features that are different from the method for producing the nonwoven fabric of the present invention. For features of the nonwoven fabric of the present invention that are not specifically described, the description of the method for producing the nonwoven fabric of the present invention described above applies as appropriate.

The nonwoven fabric of the present invention is characterized in that compound C1 is adhered to the surfaces of the constituent fibers of the nonwoven fabric, compound C2 is adhered in a scattered dot pattern to one surface of the nonwoven fabric, and the area ratio of C2 adhered to one surface of the nonwoven fabric is 20% or less.

The contents of compounds C1 and C2 in the nonwoven fabric of the present invention are not particularly limited, provided that the above-mentioned characteristics are not impaired.
The content of compound C1 in the nonwoven fabric of the present invention is, in terms of solid content, preferably 0.05 mass% or more, more preferably 0.1 mass% or more, and preferably 5 mass% or less, more preferably 2 mass% or less, based on the total mass of the nonwoven fabric.
The content of compound C2 in the nonwoven fabric of the present invention is, in terms of solid content, preferably 0.05 mass% or more, more preferably 0.1 mass% or more, and preferably 50 mass% or less, more preferably 30 mass% or less, based on the total mass of the nonwoven fabric.

The nonwoven fabric of the present invention may have an uneven surface on at least one surface consisting of convex and concave portions. Specific examples of such uneven nonwoven fabrics of the present invention include those made using nonwoven fabrics 10a to 10f shown in Figures 4 to 9 as raw material nonwoven fabrics. That is, a nonwoven fabric of the present invention is one in which compound C1 is adhered to the surface of any one of the constituent fibers of nonwoven fabrics 10a to 10f, compound C2 is adhered to one surface of the nonwoven fabric in a scattered dot pattern, and the C2 adhered area ratio on one surface of the nonwoven fabric is 20% or less.

4 to 9, the uneven surface may be a surface to which compound C2 is attached (a surface to which compound C2 is attached in a scattered dot pattern). When such an uneven nonwoven fabric is produced using an inkjet printing method in the C2 attachment step, the uneven surface (surface to which compound C2 is attached) of the produced uneven nonwoven fabric may have a lower attachment rate of compound C2 per unit area in the middle part in the height direction of the convex portions compared to other parts of the uneven surface.
The "height direction of the convex portions" is the same direction as the thickness direction Z of the nonwoven fabric (see Figure 4, etc.). When the convex portions are divided into three equal parts in the height direction (thickness direction Z), the tip side of the convex portions is the "top," the side opposite the tip side of the convex portions is the "bottom" (recess), and the portion located between the top and bottom is the "intermediate portion in the height direction of the convex portions." When a C2-containing liquid is applied to the uneven surface of a raw nonwoven fabric by inkjet printing, minute droplets of the C2-containing liquid sprayed from the nozzles of the inkjet head tend to preferentially adhere to the tops and bottoms (recesses) of the convex portions. As a result, the adhesion rate of compound C2 per unit area is low in the intermediate portion in the height direction of the convex portions. With such a nonwoven fabric, the liquid absorption ability in the intermediate portion is less likely to be inhibited by compound C2, and it can be expected that the liquid absorption performance will be improved.

The nonwoven fabric of the present invention is used for absorbent articles. In this invention, "absorbent article" refers to an article equipped with an absorbent body capable of absorbing bodily fluids (excrement) excreted from the human body, such as menstrual blood, urine, feces, and sweat. An example of an absorbent article is one worn in the crotch area of the human body, and specific examples of this include disposable sanitary products such as sanitary napkins and disposable diapers. Such sanitary products typically include an absorbent body that absorbs and retains bodily fluids, a top sheet that is positioned closer to the wearer's skin than the absorbent body and can come into contact with the wearer's skin, and a back sheet that is positioned farther from the wearer's skin than the absorbent body.

The nonwoven fabric of the present invention is particularly useful as a topsheet for absorbent articles. Absorbent articles comprising the nonwoven fabric of the present invention as a topsheet have excellent liquid absorption properties and are less likely to leave liquid residue, so that the wearer feels less sticky, has excellent dryness, and is comfortable to wear. From the viewpoint of ensuring the effects of the nonwoven fabric of the present invention, when the nonwoven fabric is used as a topsheet for an absorbent article, it is preferable that the surface of the nonwoven fabric to which compound C2 has been attached is the skin-facing surface of the absorbent article.
Here, the "skin-facing side of the absorbent article" refers to the side of the absorbent article or its constituent member (e.g., absorber) that faces the wearer's skin when the absorbent article is worn. Also, the "non-skin-facing side of the absorbent article" refers to the side of the absorbent article or its constituent member that faces away from the skin when the absorbent article is worn. In other words, the skin-facing side is the side that is relatively close to the wearer's skin, and the non-skin-facing side is the side that is relatively far from the wearer's skin. "When worn" and "worn state" refer to the normal, proper wearing position, i.e., the state in which the absorbent article is worn while maintaining the proper wearing position.

The present invention has been described above based on its preferred embodiments, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the invention.
The following supplementary notes are further disclosed regarding the above-described embodiment of the present invention.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

Examples 1 to 10
A raw nonwoven fabric and a treatment liquid to be applied thereto were prepared, and a nonwoven fabric was produced according to the following procedure. A textured nonwoven fabric having the same basic structure as nonwoven fabric 10e shown in FIG. 8 was used as the raw nonwoven fabric. A first treatment liquid containing a first treatment agent and a second treatment liquid containing a second treatment agent were used as the treatment liquids. The first treatment liquid was applied to the entire surface of all the fibers constituting the raw nonwoven fabric by a dipping method in which the raw nonwoven fabric was immersed in the first treatment liquid. Then, the second treatment liquid was applied to the textured surface of the raw nonwoven fabric in a staggered pattern (scattered dot pattern) shown in FIG. 1(a) by inkjet printing, thereby producing the target nonwoven fabric. The production conditions (treatment liquid characteristics, treatment liquid application conditions, etc.) are shown in Tables 1 and 2 below.

Comparative Examples 1 to 3
A nonwoven fabric was produced in the same manner as in Example 1, except that the raw nonwoven fabric was treated with the second treatment liquid instead of the first treatment liquid (Comparative Example 1). A nonwoven fabric was also produced in the same manner as in Example 1, except that the raw nonwoven fabric was treated with the first treatment liquid instead of the second treatment liquid (Comparative Example 2). A nonwoven fabric was also produced in the same manner as in Comparative Example 2, except that the type of first treatment agent was changed (Comparative Example 3). The production conditions (treatment liquid characteristics, treatment liquid application conditions, etc.) are shown in Table 1 below.

In Tables 1 and 2 below, the "adhesion amount in solids equivalent to the raw nonwoven fabric (adhesion amount of first treatment agent [g/ ^m2 ])" in the "First treatment liquid" column corresponds to the "adhesion amount per unit area (basis weight) of compound C1 (C1-containing liquid) on the raw nonwoven fabric," the "adhesion amount in solids equivalent to the raw nonwoven fabric (adhesion amount of second treatment agent [g/ ^m2 ])" in the "Second treatment liquid" column corresponds to the "adhesion amount per unit area (basis weight) of compound C2 (C2-containing liquid) on the raw nonwoven fabric," and the "adhesion amount of second treatment agent/adhesion amount of first treatment agent" corresponds to the "basis weight of compound C2/basis weight of compound C1."

The values in the "Water solubility [g] of first treatment agent" column in Tables 1 and 2 below were measured according to the above-mentioned <Method for measuring water solubility>. If the water solubility was 25 g or greater, "25 or greater" was entered in the corresponding column in Tables 1 and 2. The values in the "Adhesion area ratio [%] of second treatment agent" column in Tables 1 and 2 were calculated from the measurements of S1, S2, S3, and S4 using fluorescent paint according to the above-mentioned <Method for measuring C2 adhesion area ratio>. If the measured values of S1, S2, S3, and S4 were 0.5 mm or less, "0.5" was entered in the corresponding column in Tables 1 and 2.

The first treatment liquid contains 0.5 mass % of one of the following first treatment agents A and B, 69.5 mass % of isopropyl alcohol, and 30 mass % of water.
First treatment agent A (compound C2): PPG-5 alkyl ("Antifoaming material No. 8" manufactured by Kao Corporation)
First treatment agent B (compound C1): phosphate ester-type anionic surfactant (alkyl phosphate ester) ("Anphorex MP-2K" manufactured by Miyoshi Oil & Fats Co., Ltd.)

The second treatment liquid contains 25% by mass of any one of the following second treatment agents A to D and 75% by mass of ethanol.
Second treatment agent A (compound C2): PPG-5 alkyl ("Antifoaming material No. 8" manufactured by Kao Corporation)
Second treatment agent B (compound C2): POE(3) modified dimethyl silicone ("KF-6015" manufactured by Shin-Etsu Chemical Co., Ltd.)
Second treatment agent C (compound C2): paraffin oil ("Selenium White 15BL" manufactured by Sonneborn)
Second treatment agent D (compound C2): PPG-15 stearyl (NOF Corporation, "Unilube MS-70K")

Details of the raw material nonwoven fabric (concave-convex nonwoven fabric) are as follows.
- Constituent fiber of the first fiber layer: non-heat-shrinkable heat-fusible fiber with a fineness of 2.4 dtex (fiber diameter 17 μm, core-sheath composite fiber with a polyester core and a polyethylene sheath)
- Constituent fiber of the second fiber layer: heat-shrinkable fiber with a fineness of 2.3 dtex (fiber diameter 18 μm, core-sheath composite fiber with a polyethylene core and a polypropylene sheath)
Nonwoven fabric basis weight: 74 g/m ² (the basis weight of the first layer is 33 g/m ² , and the basis weight of the second layer is 41 g/m ² )

[Evaluation test]
The nonwoven fabrics of each of the Examples and Comparative Examples were evaluated for residual liquid uptake by the following method, and the results are shown in Tables 1 and 2 below.

<Method for evaluating remaining amount of liquid absorbed>
1. Preparation of Evaluation Samples A rectangular piece measuring 80 mm in MD and 60 mm in CD in plan view was cut from the nonwoven fabric to be evaluated, and attached to one side of an absorbent sheet of the same shape and size in plan view using a hot melt adhesive to prepare an evaluation sample. The nonwoven fabric to be evaluated was attached to the absorbent sheet so that the first fiber layer side (the textured side) of the nonwoven fabric faced the skin. The absorbent sheet was a wood pulp fiber aggregate with a basis weight of 200 g/ ^m2 , in which particulate absorbent polymer was uniformly distributed throughout, and the absorbent polymer had a basis weight of 50 g/ ^m2 .
2. Procedure: 1.0 g of defibered, sterile horse blood, previously adjusted to a viscosity of 8±0.1 cP, was dropped onto the horizontal, smooth surface of an acrylic plate. A sample was then placed on the dropped area so that the nonwoven fabric side of the sample was in contact with the horse blood. A weight (acrylic plate) was then placed on the sample, and a load of 0.36 g/ ^m2 was applied to the sample. Sixty seconds after the weight was placed on the sample, the weight and sample were removed from the acrylic plate, and the weight of the horse blood remaining on the surface of the acrylic plate was measured. The weight of this remaining horse blood was measured using commercially available tissue paper using the following procedure. That is, all of the horse blood remaining on the surface of the acrylic plate was absorbed with tissue paper, and the weight of the tissue paper was measured. The difference between the measured weight after absorption of the horse blood and the previously measured dry weight of the tissue paper was taken as the weight of the remaining horse blood (unit: mg).
The above procedure was carried out three times for each type of nonwoven fabric to be evaluated, and the average weight of the remaining horse blood obtained from the three procedures was taken as the residual liquid absorption amount of the nonwoven fabric to be evaluated. The residual liquid absorption amount is an index of the liquid absorption ability, and the smaller the residual liquid absorption amount value, the better the nonwoven fabric's liquid absorption ability and the less likely it is to leave liquid residue, and the higher the evaluation.

As shown in Table 1, in each Example, a first treatment agent (compound C1) with relatively high water solubility was first applied to the surface of the constituent fibers of a raw nonwoven fabric (textured nonwoven fabric), and then a second treatment agent (compound C2) with relatively low water solubility was applied to the surface (textured surface) of the raw nonwoven fabric (Feature A described above). Furthermore, a second treatment liquid (C2-containing liquid) was applied to the surface of the raw nonwoven fabric in a scattered dot pattern so that the second treatment agent application area ratio (C2 application area ratio) was 20% or less (Feature B described above). As a result, compared to comparative examples that did not have Features A and B, the amount of residual liquid absorbed by the resulting nonwoven fabric was smaller, enabling the production of a high-quality nonwoven fabric.

C1 Compound C1
C2 Compound C2
F Fiber Fi Fiber intertwining points 10a to 10e Nonwoven fabric 11 First fiber layer 12 Second fiber layer 13 Joint portion 14 Convex portion 14a Convex ridge portion 15a Convex ridge portion 15 Concave portion 16 Back side concave portion 17 Back side convex portion

Claims (7)

a C2 adhering step of adhering a compound C2 to the surface of the raw nonwoven fabric having a compound C1 adhered to the surface of the constituent fibers,
the water solubility of the compound C1 is 0.5 g or more, and the water solubility of the compound C2 is 0 g or more and 0.025 g or less;
In the C2 adhering step, the compound C2 is adhered to the surface of the raw nonwoven fabric in a scattered dot pattern so that the adhesion rate of the compound C2 per unit area is 20% or less. The method for manufacturing a nonwoven fabric for absorbent articles according to claim 1, wherein in the C2 attachment step, compound C2 is attached to the surface of the raw nonwoven fabric by inkjet printing. The method for manufacturing a nonwoven fabric for absorbent articles according to claim 1 or 2, wherein the surface of the raw nonwoven fabric is an uneven surface consisting of convex and concave portions. A nonwoven fabric for absorbent articles,
a compound C1 having a water solubility of 0.5 g or more adhered to the surface of a constituent fiber of the nonwoven fabric, and a compound C2 having a water solubility of 0 g or more and 0.025 g or less adhered in a scattered dot pattern to one surface of the nonwoven fabric;
A nonwoven fabric for absorbent articles, wherein the adhesion rate of the compound C2 per unit area on one surface of the nonwoven fabric is 20% or less. the adhesion portion of the compound C2 has a long axis direction and a short axis direction perpendicular to the long axis direction in a plan view,
the scattered pattern is formed by a plurality of rows of the attachment portions of the compound C2 arranged intermittently in the major axis direction with the major axis direction aligned, and the rows are arranged intermittently in the minor axis direction;
5. The nonwoven fabric for absorbent articles according to claim 4, wherein a ratio of a length S2 of an attachment portion in the minor axis direction to a spacing S1 between attachment portions of the plurality of compounds C2 adjacent to each other in the minor axis direction is 0.6 or less. the adhesion portion of the compound C2 has a long axis direction and a short axis direction perpendicular to the long axis direction in a plan view,
the scattered pattern is formed by a plurality of rows of the attachment portions of the compound C2 arranged intermittently in the major axis direction with the major axis direction aligned, and the rows are arranged intermittently in the minor axis direction;
6. The nonwoven fabric for absorbent articles according to claim 4, wherein a ratio of a length S4 of a plurality of adjacent attached portions of the compound C2 in the longitudinal direction to a spacing S3 of the attached portions is 0.6 or less. one surface of the nonwoven fabric is an uneven surface consisting of convex portions and concave portions,
6. The nonwoven fabric for absorbent articles according to claim 4, wherein the adhesion rate of the compound C2 per unit area is lower in a middle portion in the height direction of the protrusions than in other portions of one surface of the nonwoven fabric.