Nonwoven fabric for absorbent article

Abstract

To provide a nonwoven fabric for absorbent articles capable of stably exhibiting a high level of dryness for a long period of time.SOLUTION: A nonwoven fabric for absorbent articles is formed by adhering a fiber treatment agent to a surface of constituent fibers, where the fiber treatment agent contains a compound A satisfying the following (1) to (4), and where an endothermic amount of the fiber treatment agent is 1.1 mJ / mg or more and 60 mJ / mg or less: (1) the spreading coefficient with respect to liquid having a surface tension of 50 mN / m is more than 0 mN / m and 50 mN / m or less; (2) the water-solubility is 0 g or more and 0.025 g or less; (3) the interface tension with respect to the liquid having the surface tension of 50 mN / m is 20 mN / m or less; and (4) the melting point is less than 40°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a nonwoven fabric for absorbent articles which uses a fiber treatment agent used for the purpose of modifying the fibers. [Background technology]

[0002] The present applicant previously proposed an improved technology for liquid film cleaving agents in Patent Document 1. The liquid film cleaving agent described in Patent Document 1 is an agent that inhibits the formation of liquid films between constituent fibers of a nonwoven fabric or on the surface of constituent fibers, and nonwoven fabrics containing this agent are less likely to produce liquid residue on the surface, i.e., have excellent dryness, and are suitable as topsheets for absorbent articles such as sanitary napkins and disposable diapers.

[0003] Furthermore, in absorbent articles, friction with the constituent members of the absorbent article, contact with the wearer's excrement, etc. may cause troubles such as abrasions, rashes, itchiness, etc. on the wearer's skin. In order to prevent such skin troubles, various agents such as petrolatum, cream, lotion, etc. have conventionally been applied to the constituent members of the absorbent article that come into contact with the wearer's skin. For example, Patent Documents 2 and 3 describe applying lotion to the skin-facing surface of the topsheet of an absorbent article (the surface of the absorbent article that faces the wearer's skin). The lotion described in Patent Document 2 contains a specific liquid polyol polyester emollient and a fixing agent that fixes the emollient to the top sheet, and is said to migrate from the top sheet to the wearer's skin while the absorbent article is being worn, reducing the adhesion of excrement to the skin and improving the softness of the skin. The lotion described in Patent Document 3 contains a skin softener, wax, and a thickener such as a polyolefin resin, and is said to function as a lubricant, suppress abrasions caused by the components of the absorbent article, and migrate from the top sheet to the skin to promote the maintenance of healthy skin.

[0004] As in the lotions described in Patent Documents 2 and 3, when a lotion coating is formed on the skin-facing surface of a topsheet by immobilizing or increasing the viscosity of the lotion using a fixative or thickener, there is a problem in that the active ingredients are difficult to release from the lotion coating. Furthermore, when an absorbent article is worn, pressure, such as body pressure, acts on the skin-facing surface of the topsheet, causing the lotion coating to migrate toward the inside of the absorbent article, preventing the active ingredients released from the lotion coating from acting on the wearer's skin. Patent Document 4 describes a technique that can solve this problem: providing multiple gel regions containing a gel lotion and non-gel regions without a gel lotion on the skin-facing surface of the topsheet of an absorbent article. The gel lotion contains a styrene-based elastomer as a gelling agent and a hydrocarbon as a lotion. The styrene-based elastomer preferably has a hard segment, such as a polystyrene block, and a soft segment, such as a polyolefin block, and the hydrocarbon is preferably a paraffin-based hydrocarbon. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-117981 [Patent Document 2] Special Publication No. 11-510416 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-541982 [Patent Document 4] International Publication No. 2015 / 186376 Summary of the Invention [Problem to be solved by the invention]

[0006] Although the liquid film splitting agent described in Patent Document 1 is effective in improving the dryness of nonwoven fabrics, there is room for improvement in the durability of the dryness over time. For example, when a nonwoven fabric having the liquid film splitting agent described in Patent Document 1 attached to the surface of the constituent fibers is used as a topsheet for an absorbent article, the dryness of the nonwoven fabric may deteriorate over time. Patent Documents 2 to 4 do not mention the problem of deterioration of dryness over time caused by such liquid film splitting agents. A nonwoven fabric for absorbent articles that can stably exhibit a high level of dryness over a long period of time has not yet been provided.

[0007] An object of the present invention is to provide a nonwoven fabric for absorbent articles that can stably exhibit a high level of dryness for a long period of time. [Means for solving the problem]

[0008] The present invention relates to a nonwoven fabric for absorbent articles having a fiber treating agent adhered to the surfaces of constituent fibers, the fiber treating agent containing a compound A that satisfies at least one of the following (1) to (4): (1) The expansion coefficient for a liquid with a surface tension of 50 mN / m is greater than 0 mN / m and less than or equal to 50 mN / m. (2) The water solubility is 0 g or more and 0.025 g or less. (3) The interfacial tension with a liquid having a surface tension of 50 mN / m is 20 mN / m or less. (4) The melting point is less than 40°C. In one embodiment of the nonwoven fabric for absorbent articles of the present invention, it is preferable that the compound A satisfies all of the above (1) to (4). In one embodiment of the nonwoven fabric for absorbent articles of the present invention, the endothermic amount of the fiber treatment agent is preferably 1.1 mJ / mg or more and 60 mJ / mg or less. Other features, advantages and embodiments of the present invention are described below. [Effects of the Invention]

[0009] The nonwoven fabric for absorbent articles of the present invention can stably exhibit a high level of dryness for a long period of time, and when used as a component that can come into direct contact with the skin of a wearer of an absorbent article, such as a topsheet in an absorbent article, it can stably provide an excellent dry feeling. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a liquid film formed in the gaps between the fibers of a nonwoven fabric. [Figure 2] FIG. 2 is an explanatory diagram of the process of breaking up a liquid film by the fiber treatment agent used in the present invention, where (A1) to (A4) are schematic side views of the liquid film being broken up, and (B1) to (B4) are schematic perspective views of the same liquid film from above. DETAILED DESCRIPTION OF THE INVENTION

[0011] The nonwoven fabric for absorbent articles of the present invention (hereinafter also referred to simply as "the nonwoven fabric of the present invention") has a fiber treatment agent adhered to the surface of the constituent fibers. First, the fiber treatment agent used in the present invention will be described below.

[0012] The fiber treating agent contains a compound A that satisfies at least one, preferably all, of the following (1) to (4): (1) The expansion coefficient for a liquid with a surface tension of 50 mN / m is greater than 0 mN / m and less than or equal to 50 mN / m. (2) The water solubility is 0 g or more and 0.025 g or less. (3) The interfacial tension with a liquid having a surface tension of 50 mN / m is 20 mN / m or less. (4) The melting point is less than 40°C.

[0013] Compound A satisfying the above conditions (1) to (4) typically functions as a liquid membrane splitting agent. In the present invention, the term "liquid membrane splitting agent" refers to an agent that disrupts the formation of a liquid membrane by splitting the liquid membrane formed between or on the surface of fibers of a fiber assembly when a liquid, specifically, excrement such as menstrual blood or urine, comes into contact with the fiber assembly, such as a nonwoven fabric. The splitting of the liquid membrane is achieved by the liquid membrane splitting agent's action of destabilizing the liquid membrane by pushing aside a portion of the liquid membrane layer. This action of the liquid membrane splitting agent allows liquid to pass through the fiber assembly without remaining in the narrow interfiber spaces. Therefore, a fiber assembly containing a liquid membrane splitting agent has excellent liquid permeability. As a result, for example, even when the constituent fibers of the fiber assembly are thinned to narrow the interfiber distance, both a soft feel and reduced liquid residue can be achieved. Such a fiber assembly is useful as a component of absorbent articles such as sanitary napkins and disposable diapers. In the following description, "compound A" can be rephrased as "liquid membrane cleaving agent" unless otherwise specified.

[0014] With regard to the above (1), the "expansion coefficient for a liquid having a surface tension of 50 mN / m" of compound A is a value calculated based on the following formula (A) from measurements obtained by the measurement method described below in an environment of an ambient temperature of 25°C and a relative humidity (RH) of 65%. The "liquid with a surface tension of 50 mN / m" is an expansion coefficient that assumes the excrement excreted from the human body, such as menstrual blood and urine. γ in the following formula (A) w and γ wo The "liquid film" in this case means the liquid phase of "a liquid with a surface tension of 50 mN / m", and includes both the liquid in a state where a film is formed between fibers or on the fiber surface, and the liquid in a state before the film is formed, and is also simply called the liquid. w and γ o The "surface tension" in this specification means the interfacial tension at the interface between the liquid film and the gas phase of compound A (measurement object), and is distinguished from the interfacial tension between the liquid phase and the liquid film of compound A (measurement object). This distinction is also applicable to other descriptions in this specification. S=γ w -γ o -γ wo (A) gammaw : Surface tension of liquid film (liquid) gamma o : Surface tension of compound A gamma wo :Interfacial tension between compound A and liquid film

[0015] As can be seen from the above formula (A), the spreading coefficient (S) of compound A is determined by the surface tension (γ o ) becomes smaller, and the interfacial tension (γ wo ) becomes smaller. When this spreading coefficient exceeds 0 mN / m, compound A exhibits high mobility, i.e., high diffusibility, on the surface of the liquid film formed in the narrow region between fibers. From this viewpoint, the spreading coefficient of compound A is preferably 3 mN / m or more, more preferably 10 mN / m or more, even more preferably 15 mN / m or more, even more preferably 20 mN / m or more, and particularly preferably 25 mN / m or more. On the other hand, although there is no particular restriction on the upper limit, from the above formula (A), the upper limit is determined by the surface tension of the liquid forming the liquid film, such as 50 mN / m when a liquid with a surface tension of 50 mN / m is used, 60 mN / m when a liquid with a surface tension of 60 mN / m is used, and 70 mN / m when a liquid with a surface tension of 70 mN / m is used. Therefore, in the present invention, from the viewpoint of using a liquid with a surface tension of 50 mN / m, the spreading coefficient of compound A is 50 mN / m or less.

[0016] With regard to (2) above, the "water solubility" of compound A refers to the soluble mass of compound A in 100 g of ion-exchanged water, and is a value measured in an environment at an ambient temperature of 25°C and a relative humidity (RH) of 65% based on the measurement method described below. When compound A has a water solubility of 0 g or more and 0.025 g or less, it is difficult to dissolve in aqueous liquids, forms an interface with the liquid film, and has high mobility (diffusibility) on the surface of the liquid film. From the same viewpoint, the water solubility of compound A is preferably 0.0025 g or less, more preferably 0.0015 g or less, and even more preferably less than 0.0001 g. Furthermore, the water solubility of compound A is preferably as low as possible, and is preferably 0 g or more. From the viewpoint of diffusibility into the liquid film, it is preferable that the water solubility of compound A is 1.0 x 10 -9It is practical to set the water solubility of Compound A to 1000 mg or more. The water solubility of Compound A is also considered to be applicable to menstrual blood, urine, etc., which are mainly composed of water.

[0017] Regarding the above (3), the fact that the "interfacial tension with respect to a liquid having a surface tension of 50 mN / m" of compound A is 20 mN / m or less is a variable that determines the value of the expansion coefficient (S) in the above formula (A), namely, the "interfacial tension with the liquid film of compound A" (γ wo ) is equal to or less than 20mN / m. wo By keeping the interfacial tension low, the expansion coefficient of compound A is improved, compound A is more likely to migrate from the fiber surface to the center of the liquid film, and the liquid film splitting effect is exhibited. From this viewpoint, the "interfacial tension with a liquid having a surface tension of 50 mN / m" of compound A is more preferably 17 mN / m or less, even more preferably 13 mN / m or less, even more preferably 10 mN / m or less, particularly preferably 9 mN / m or less, and particularly preferably 1 mN / m or less. On the other hand, the lower limit of the interfacial tension is not particularly limited, and it is sufficient that it is greater than 0 mN / m from the viewpoint of insolubility in the liquid film. Note that when the interfacial tension is 0 mN / m, i.e., when compound A dissolves in the liquid film, it is difficult to form an interface between the liquid film and compound A, so the formula (A) does not hold and compound A does not expand. As can be seen from the formula (A), the spreading coefficient varies depending on the surface tension of the target liquid. For example, if the surface tension of the target liquid is 72 mN / m, the surface tension of compound A is 21 mN / m, and the interfacial tension between them is 0.2 mN / m, the spreading coefficient is 50.8 mN / m. Furthermore, if the surface tension of the target liquid is 30 mN / m, the surface tension of compound A is 21 mN / m, and the interfacial tension between them is 0.2 mN / m, the expansion coefficient is 8.8 mN / m. In either case, the larger the expansion coefficient of the material, the greater the liquid film splitting effect. In this specification, the values ​​are defined for a surface tension of 50 mN / m. However, even if the surface tension differs, the relationship between the numerical expansion coefficients of the respective substances remains unchanged. Therefore, even if the surface tension of excrement changes depending on the physical condition from day to day, the substance with a larger expansion coefficient will exhibit a better liquid film disruption effect.

[0018] With regard to (4) above, the "melting point" of compound A refers to the temperature at which a solid melts and becomes liquid. In order for the fiber treatment agent to exhibit the aforementioned liquid membrane cleavage effect, compound A contained in the fiber treatment agent must exist in a liquid state when it comes into contact with excrement such as menstrual blood or urine. From this perspective, the melting point of compound A is less than 40°C, preferably 35°C or lower, more preferably 20°C or lower, even more preferably 10°C or lower, and even more preferably 0°C or lower. Furthermore, the melting point of compound A is preferably -220°C or higher, more preferably -180°C or higher.

[0019] The surface tension (γ w ) and the surface tension of compound A (γ o ), "Interfacial tension between compound A and the liquid film (γ wo ),” “water solubility of compound A,” and “melting point of compound A” are measured by the following methods.

[0020] In the following measurement methods, when the object to be measured is a deposit attached to a fiber (hereinafter also referred to as "fiber deposit"), the fiber is washed with an organic solvent (e.g., hexane, methanol, ethanol, etc.), and the organic solvent (the organic solvent containing the object to be measured) after washing is dried to obtain the fiber deposit. The mass of the fiber deposit thus obtained can be used to calculate the content of the fiber treatment agent in a fiber assembly such as a nonwoven fabric (e.g., a nonwoven fabric). The mass of the fiber deposits is calculated by the surface tension (γ o ), interfacial tension (γ wo), the amount required for measurement is secured by identifying the fiber attachment and, if the fiber attachment is a commercially available product, procuring the commercially available product, or by synthesizing the fiber attachment if it is not commercially available. The "identification of the fiber attachment (object to be measured)" can be carried out, 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 using high-performance liquid chromatography, and then 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). In particular, the surface tension (γ o ) and interfacial tension (γ wo Regarding the measurement of ), if the fiber attachment is solid at room temperature and pressure, the fiber attachment is heated until it reaches its melting point + 5°C to cause a phase transition to a liquid, and the measurement is carried out at that temperature, i.e., on the liquid fiber attachment. 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.

[0021] In this specification, "normal temperature and normal pressure" refers to an environment with an atmospheric temperature of 25°C and a pressure of 1 atmosphere.

[0022] <Surface tension of liquid film (γ w ) Measurement method> Measurements are made using a platinum plate by the plate method (Wilhelmy method) in an environment with an ambient temperature of 25°C and a relative humidity (RH) of 65%. The measurement device used is the automatic surface tensiometer "CBVP-Z" (trade name, manufactured by Kyowa Interface Science Co., Ltd.). The platinum plate used is 99.9% pure and 25 mm wide and 10 mm long. The "liquid with a surface tension of 50 mN / m" is a solution whose surface tension has been adjusted to 50±1 mN / m using the measurement method described above by adding polyoxyethylene sorbitan monolaurate (manufactured by Kao Corporation, trade name: Leoall Super TW-L120), a nonionic surfactant, to deionized water.

[0023] <Surface tension of compound A (γ o ) Measurement method> The surface tension of the liquid film (γ w As with the measurement of (1), the measurement is carried out using the same equipment and the plate method in an environment with an ambient temperature of 25°C and a relative humidity (RH) of 65%. If the object to be measured (fiber adhesion object) is solid at room temperature and normal pressure, as mentioned above, it is heated to the melting point of the object to be measured + 5°C to cause a phase transition to liquid, and the measurement is carried out at that temperature.

[0024] <Interfacial tension with the liquid film of compound A (γ wo ) Measurement method> Measurements can be performed using the pendant drop method in an ambient temperature of 25°C and a relative humidity (RH) of 65%. An automatic interfacial viscoelasticity analyzer (TECLIS-ITCONCEPT, product name THE TRACKER, or KRUSS, product name DSA25S) can be used. In the pendant drop method, the adsorption of nonionic surfactants contained in a liquid with a surface tension of 50 mN / m begins as soon as the drop is formed, and the interfacial tension decreases over time. Therefore, the interfacial tension is read when the drop is formed (0 seconds). If the object being measured (fiber adhesion material) is solid at room temperature and pressure, as mentioned above, it is heated to the melting point of the object to +5°C to cause a phase transition to a liquid, and measurements are then performed at that temperature. Furthermore, when measuring interfacial tension, the pendant drop method can be difficult to use if the density difference between the object being measured and a liquid with a surface tension of 50 mN / m is relatively small, if the object being measured has a very high viscosity, or if the interfacial tension value is below the limit of pendant drop measurement. In such cases, measurements can be performed using the spinning drop method at an ambient temperature of 25°C and a relative humidity (RH) of 65%. A spinning drop interfacial tensiometer (KRUSS, product name SITE100) can be used. For this measurement, the interfacial tension is read when the drop shape stabilizes. If the object being measured (fiber adhesion material) is solid at room temperature and pressure, it is heated to the melting point of the object + 5°C to cause a phase transition to a liquid, and the measurement is continued at that temperature. When the interfacial tension can be measured by both measuring devices, the smaller interfacial tension value is adopted as the measurement result.

[0025] <Method for measuring the water solubility of compound A> 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 object to be measured (fiber deposits). The degree of dissolution is visually observed, and the amount of dissolved object is taken as the water solubility when the object no longer dissolves, i.e., when any one of floating, precipitating, precipitation, or cloudiness is visually observed. Specifically, the object to be measured is added in 0.0001 g increments and measured. When it is observed that even 0.0001 g does not dissolve, it is considered "less than 0.0001 g." When 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 object to be measured is a surfactant, "dissolution" refers to both monodisperse dissolution and micellar dissolution. The amount of dissolution when floating, precipitating, precipitation, or cloudiness is observed is taken as the water solubility.

[0026] <Method for measuring the melting point of compound A> Using a differential scanning calorimeter, the temperature of the object to be measured (fiber-attached material) is raised from -20 to 200°C at a rate of 20°C / min, the melting peak temperature is measured, and this measured value is the melting point of the object to be measured. In measuring this melting peak temperature, the weight of the object to be measured is 2 mg. As the differential scanning calorimeter, for example, a "DSC7000X" manufactured by Hitachi High-Tech Corporation can be used.

[0027] Compound A that satisfies the above (1) to (4) spreads on the surface of the liquid film without dissolving, and can push away the liquid film layer from near the center of the liquid film. This destabilizes the liquid film and causes it to split. Since the fiber treatment agent contains compound A that exerts such a liquid film splitting effect, when it is applied to a fiber assembly such as a nonwoven fabric, it exhibits the liquid film splitting effect and can improve the dryness of the application site.

[0028] The liquid film splitting effect of the fiber treatment agent will be specifically described with reference to FIGS. Fig. 1 shows a state in which a liquid film 2 is formed in the gaps between fibers 1 constituting a nonwoven fabric, and Fig. 2 shows the process in which the liquid film 2 is cleaved by a fiber treating agent 3. The fiber treating agent 3 is the fiber treating agent used in the present invention, and contains a compound A that satisfies the above (1) to (4). As shown in FIG. 1, highly viscous excrement such as menstrual blood tends to form a liquid film 2 in the narrow spaces between fibers. In response, fiber treatment agent 3 destabilizes and breaks the liquid film 2, inhibiting its formation and promoting its drainage from the nonwoven fabric. First, as shown in FIGS. 2(A1) and (B1), the fiber treatment agent 3 adhering to the surface of fiber 1 of the nonwoven fabric migrates from fiber 1 to liquid film 2, and then migrates along the surface of liquid film 2 while maintaining its interface with liquid film 2. Next, as shown in FIGS. 2(A2) and (B2), the fiber treatment agent 3 pushes aside part of liquid film 2 and penetrates inward in the thickness direction of liquid film 2, gradually transforming liquid film 2 into a non-uniform, thin film as shown in FIGS. 2(A3) and (B3). As a result, holes appear in liquid film 2, causing it to burst and tear, as shown in FIGS. 2(A4) and (B4). The liquid such as menstrual blood that had formed the liquid film 2 thus ruptured turns into droplets and can easily pass through the fibers of the nonwoven fabric, thereby reducing the amount of remaining liquid.

[0029] The liquid film-cleaving action of the fiber treatment agent is not limited to the liquid film between intersecting fibers as shown in Figure 1, but is also exerted on liquid films clinging to fiber surfaces. That is, the fiber treatment agent can migrate on the liquid film clinging to the fiber surface, push aside part of the liquid film, and cleave the liquid film. In this case, the fiber treatment agent can cleave the liquid film clinging to the fiber surface and prevent its formation by its hydrophobic effect, even if the fiber treatment agent itself does not migrate on the fiber surface to the liquid film.

[0030] In this way, the fiber treatment agent does not modify the liquid by, for example, lowering the surface tension of the liquid film, but rather pushes aside and disrupts the liquid film itself that forms between fibers and on the fiber surface, thereby promoting the drainage of the liquid from a fiber assembly such as a nonwoven fabric, thereby reducing the amount of liquid remaining in the fiber assembly. Furthermore, when a nonwoven fabric having a fiber treatment agent applied to the surface of the constituent fibers is incorporated into an absorbent article as a topsheet, liquid retention between the fibers is suppressed, ensuring a path for liquid to pass through to the absorbent body. This increases liquid permeability, suppresses liquid flow on the sheet surface, and increases the liquid absorption rate. In particular, it can increase the absorption rate of liquid that tends to remain between fibers, such as highly viscous menstrual blood. As a result, stains such as redness on the topsheet are less noticeable, allowing the absorbency to be felt, resulting in a safe and reliable absorbent article.

[0031] In order to more reliably exert the liquid film splitting effect of the fiber treatment agent, the smaller the surface tension of compound A, the better, and from this viewpoint, the surface tension of compound A is preferably 40 mN / m or less, more preferably 35 mN / m or less, even more preferably 30 mN / m or less, and even more preferably 25 mN / m or less. On the other hand, from the viewpoint of the durability of compound A, the surface tension of compound A is practically 1 mN / m or more, preferably 5 mN / m or more, more preferably 10 mN / m or more, and even more preferably 15 mN / m or more.

[0032] The content of compound A in the fiber treatment agent is preferably more than 75.0% by mass, more preferably 80.0% by mass or more, and even more preferably 90.0% by mass or more, from the viewpoint of ensuring the liquid membrane splitting effect of compound A. On the other hand, the upper limit of the content of compound A in the fiber treatment agent is preferably less than 99.9% by mass, more preferably 99.8% by mass or less, from the viewpoint of leaving room for the fiber treatment agent to contain other components such as compound B described below.

[0033] Specific examples of liquid membrane cleaving agents that can be used as compound A in fiber treatment agents are described below. The liquid membrane cleaving agents described below are water-insoluble or poorly water-soluble by satisfying the above-mentioned (1) to (4), and exhibit a liquid membrane cleaving effect in fiber assemblies such as nonwoven fabrics. In contrast, conventional fiber treatment agents made of surfactants and the like are basically water-soluble and cannot exhibit the above-mentioned liquid membrane cleaving effect. Unless otherwise specified, the above description of compound A applies to the liquid membrane cleaving agent described below. In the following description, the "liquid membrane cleaving agent" can be rephrased as "compound A" unless otherwise specified.

[0034] The mass average molecular weight of the liquid membrane cleaving agent is preferably 400 or more. The mass average molecular weight of the liquid membrane cleaving agent significantly affects the viscosity of the liquid membrane cleaving agent and, by extension, the viscosity of the fiber treating agent containing the liquid membrane cleaving agent. If the viscosity of the liquid membrane cleaving agent is too low, the migration of the fiber treating agent from the fiber to the liquid film is promoted, causing liquids such as menstrual blood to flow down as they pass through the fiber assembly, thereby reducing the durability of the liquid membrane cleaving effect. From the viewpoint of achieving a viscosity that sufficiently maintains the liquid membrane cleaving effect of the fiber treating agent, the mass average molecular weight of the liquid membrane cleaving agent is more preferably 600 or more, and even more preferably 800 or more. On the other hand, if the viscosity of the liquid membrane cleaving agent is too high, the diffusibility of the fiber treating agent may decrease. Therefore, from the viewpoint of achieving a viscosity that maintains the diffusibility, the mass average molecular weight of the liquid membrane cleaving agent is preferably 50,000 or less, more preferably 20,000 or less, even more preferably 10,000 or less, and even more preferably 5,000 or less.

[0035] The mass average molecular weight of the liquid membrane cleaving agent is measured using a gel permeation chromatograph (GPC) "CCPD" (trade name, manufactured by Tosoh Corporation). The measurement conditions are as follows. The molecular weight is calculated using polystyrene as the converted value. Separation column: GMHHR-H + GMHHR-H (cation) Eluent: L-Farmin DM20 / CHCl3 Solvent flow rate: 1.0 ml / min Separation column temperature: 40℃

[0036] 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 A. These compounds will be described below.

[0037] Specific examples of the silicone compound (liquid membrane cleaving agent) include the following. Dimethicone, dimethiconol, and cyclomethicone (hereinafter referred to as "first silicone compounds") Amino-modified silicone (hereinafter also referred to as "second silicone compound") Polyether-modified silicone (hereinafter also referred to as "third silicone compound") A silicone compound other than the first to third silicone compounds (hereinafter also referred to as the "fourth silicone compound")

[0038] A preferred example of the first silicone compound is a silicone compound represented by the following general formula (1).

[0039] [ka] [In formula (1), R 10 represents a methyl group or a hydroxy group, and two R 10 may combine together to form an oxygen atom to form a ring, and a represents a number from 1 to 20,000.

[0040] A preferred example of the first silicone compound represented by the general formula (1) is high-polymerization dimethylpolysiloxane. Commercially available products include BY11-026, BY22-19, and FZ-3125 (all manufactured by Dow Corning Toray Co., Ltd.). The high-polymerization dimethylpolysiloxane can also be used in a form dissolved or dispersed in a liquid hydrocarbon oil. Examples of such liquid hydrocarbon oils include low-polymerization dimethylpolysiloxane, liquid silicone oils such as cyclomethicone, and isoparaffin.

[0041] As the second silicone compound, various amino-modified silicones can be used, but a preferred example is one represented by the following general formula (2).

[0042] [ka] [In formula (2), R11 represents a methyl group or a hydroxy group, X represents a divalent hydrocarbon group having 2 to 6 carbon atoms, and b and c each represent a number from 1 to 20,000.]

[0043] A preferred example of the second silicone compound represented by the general formula (2) is amodimethicone having a mass-average molecular weight of approximately 3,000 to 100,000. The amodimethicone is a name according to the International Nomenclature of Cosmetic Ingredients (INCI). The amodimethicone is preferably used as an aqueous emulsion. Commercially available products include SM8704C (manufactured by Dow Corning Toray Co., Ltd.) and DC929 (manufactured by Dow Corning Co., Ltd.).

[0044] Another preferred example of the second silicone compound is bis(C13-15 alkoxy)PG amodimethicone represented by the following general formula (3): Commercially available products include 8500 Conditioning Agent (all manufactured by Dow Corning Corporation).

[0045] [ka] [In formula (3), R 12 represents a linear or branched alkyl group having 13 to 15 carbon atoms, 75% of Y's represent the group -CH2CH(OH)CH2OH, and the remaining 25% of Y's represent hydrogen atoms.]

[0046] Yet another preferred example of the second silicone compound is a copolymer containing polyoxyalkylene in the main chain, a specific example of which is bisisobutyl PEG-15 / amodimethicone represented by the following general formula (4): Commercially available products include FZ-3789 and Silicone SS-3588 (both manufactured by Dow Corning Toray Co., Ltd.).

[0047] [ka] [In formula (4), R 13 represents an isobutylene group, d represents a number of 2 or more, preferably 2 to 1000, e represents a number of 1 or more, preferably 1 to 50, and f represents a number of 2 or more, preferably 2 to 100.]

[0048] Various polyether-modified silicones can be used as the third silicone compound, but a preferred example is "dimethicone in which some of the methyl groups of dimethicone have been substituted with polyethylene glycol or polypropylene glycol" (hereinafter also referred to as "dimethicone A").

[0049] A preferred example of dimethicone A is "PEG-n dimethicone" (named by INCI) represented by the following general formula (5) and having a mass-average molecular weight of approximately 2,000 to 100,000. In the PEG-n dimethicone, n represents an integer. Specific examples of the PEG-n dimethicone include PEG-3 dimethicone, PEG-7 dimethicone, PEG-8 dimethicone, PEG-9 dimethicone, PEG-10 dimethicone, PEG-12 dimethicone, and PEG-14 dimethicone.

[0050] [ka] [In formula (5), g and h each represent a number from 1 to 2000, n represents 2 or 3, and i represents a number from 1 to 100.]

[0051] Other preferred examples of dimethicone A include "bisPEG-n dimethicone" (named by INCI) and "bis(PEG / PPG-n / m) dimethicone" (named by INCI) represented by the following general formula (6). These are dimethicones with POP(12) attached to both ends. In the bisPEG-n dimethicone, n represents an integer. Specific examples of the bisPEG-n dimethicone include bisPEG-4 dimethicone, bisPEG-8 dimethicone, and bisPEG-12 dimethicone. In the bis(PEG / PPG-n / m)dimethicone, n and m each represent an integer. Specific examples of the bis(PEG / PPG-n / m)dimethicone include bis(PEG / PPG-14 / 14)dimethicone, bis(PEG / PPG-20 / 20)dimethicone, and bis(PEG / PPG-21 / 7)dimethicone.

[0052] [ka] [In formula (6), the sum of j, k, l, and m is a number from 4 to 100, and h is a number from 1 to 2000. However, the sum of j and m may be 0, or the sum of k and l may be 0.]

[0053] Yet another preferred example of dimethicone A is "polysilicone-13" (name given by INCI) represented by the following general formula (7).

[0054] [ka] [In formula (7), j, k, and l each represent a number from 1 to 1000, and m represents a number from 1 to 2000.]

[0055] Specific examples of the fourth silicone compound include methylphenylpolysiloxane, fatty acid-modified silicone, alcohol-modified silicone, alkoxy-modified silicone, epoxy-modified silicone, fluorine-modified silicone, and alkyl-modified silicone.

[0056] Specific examples of the non-silicone compound (liquid membrane cleaving agent) include the following. Polyether compounds selected from polyalkylene glycols and polyoxyalkylene alkyl ethers Hydrocarbon compounds with 5 to 18 carbon atoms (hereinafter referred to as "hydrocarbon compounds with C5 to C18") Saturated fatty acids or their derivatives with 9 or fewer carbon atoms, or unsaturated fatty acids or their derivatives with 22 or fewer carbon atoms (hereinafter referred to as "C9 or fewer saturated fatty acids or C22 or fewer unsaturated fatty acids")

[0057] As the polyalkylene glycol (liquid membrane cleaving agent), various polyalkylene glycols can be used, for example, polypropylene glycol to which propylene glycol is added preferably in an amount of 5 to 70 moles, more preferably 7 to 60 moles, and even more preferably 10 to 50 moles. Preferred examples of the polyalkylene glycol (liquid membrane cleaving agent) include those represented by the following general formulas (8) and (9).

[0058] HO-(C n H 2n O) z -H (8) [In formula (8), n represents a number from 3 to 5, and z represents a number from 1 to 200.]

[0059] HO-(C2H4O) y -(C n H 2n O) z -H (9) [In formula (9), y represents a number from 0 to 200, n represents a number from 3 to 5, and z represents a number from 1 to 200.]

[0060] As the polyoxyalkylene alkyl ether (liquid membrane cleaving agent), various polyoxyalkylene alkyl ethers can be used, for example, lauryl ether, myristyl ether, cetearyl ether, and stearyl ether, each having preferably 5 to 70 moles, more preferably 7 to 60 moles, and even more preferably 10 to 50 moles of propyleneoxy groups added thereto. Preferred examples of the polyoxyalkylene alkyl ether (liquid membrane cleaving agent) include those represented by the following general formulas (10) and (11).

[0061] R 14 O-(Cn H 2n O) z -H (10) [In formula (10), R 14 represents a linear or branched, saturated or unsaturated hydrocarbon group having 10 to 22 carbon atoms, n represents a number from 3 to 5, and z represents a number from 1 to 200.]

[0062] R 14 O-(C2H4O) y -(C n H 2n O) z -H (11) [In formula (11), R 14 represents a linear or branched, saturated or unsaturated hydrocarbon group having 10 to 22 carbon atoms, y represents a number from 0 to 200, n represents a number from 3 to 5, and z represents a number from 1 to 200.]

[0063] In the polyether compounds (polyalkylene glycols and polyoxyalkylene alkyl ethers), the spreading coefficient, surface tension, and water solubility can each be set within a predetermined range, for example, by the number of moles of polyoxyalkylene groups. From this perspective, the number of moles of polyoxyalkylene groups is preferably 1 to 400. From the viewpoint of increasing the spreading coefficient and strengthening the liquid film splitting effect by lowering the interfacial tension, the number of moles is more preferably 5 or more, even more preferably 7 or more, and even more preferably 10 or more. On the other hand, from the viewpoint of preventing excessive entanglement of molecular chains and a decrease in diffusibility in the liquid film, the number of added moles is more preferably 70 or less, even more preferably 60 or less, and even more preferably 50 or less. Furthermore, the aforementioned expansion coefficient, surface tension, interfacial tension, and water solubility can be set within a predetermined range by, for example, 1) using a water-soluble polyoxyethylene group in combination with a water-insoluble polyoxypropylene group and a polyoxybutylene group in the polyether compound, 2) changing the chain length of the hydrocarbon chain, 3) using a compound having a branched hydrocarbon chain, 4) using a compound having a double bond in the hydrocarbon chain, 5) using a compound having a benzene ring or a naphthalene ring in the hydrocarbon chain, or 6) appropriately combining the above 1) to 5).

[0064] The number of carbon atoms of the hydrocarbon compound (liquid film cleaving agent) having from C5 to C18 is preferably 16 or less, more preferably 14 or less, from the viewpoint that the liquid state spreads more easily on the liquid film surface. The hydrocarbon compound having from C5 to C18 is not limited to a straight chain but may be a branched chain, and the chain is not particularly limited to being saturated or unsaturated. Among them, those that are liquid at room temperature are preferably used alone. As the hydrocarbon compound of C5 to C18, extracts from petroleum, natural gas, etc. can be used.

[0065] With regard to the saturated fatty acid of C9 or less or unsaturated fatty acid of C22 or less (liquid membrane cleavage agent), the number of carbon atoms of the saturated fatty acid of C9 or less or its derivative is preferably 3 or more, more preferably 5 or more, from the viewpoint of setting the spreading coefficient, surface tension, and water solubility within predetermined ranges. From the same viewpoint, the number of carbon atoms of the unsaturated fatty acid of C22 or less or its derivative is preferably 5 or more, more preferably 8 or more, and preferably 20 or less, more preferably 18 or less. Examples of the saturated fatty acids of C9 or less include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid. Examples of the C22 or lower unsaturated fatty acids include irritoleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, and docosahexanoic acid.

[0066] As the compound A contained in the fiber treatment agent, the liquid membrane cleaving agent described in Patent Document 1 can also be used.

[0067] The fiber treatment agent is characterized in that the endothermic heat measured by the following method is 1.1 mJ / mg or more and 60 mJ / mg or less. As mentioned above, the liquid film splitting agent described in Patent Document 1 is effective in improving the dryness of nonwoven fabrics, but there is room for improvement in the durability of the dryness over time. The present inventors conducted various studies aimed at improving the durability of the dryness over time of fiber assemblies such as nonwoven fabrics using a liquid film splitting agent that is liquid and fluid at room temperature and normal pressure. As a result, they discovered that the main cause of the deterioration over time of the dryness of fiber assemblies having the liquid film splitting agent attached to the surfaces of the constituent fibers is the migration of the liquid film splitting agent over time. For example, if a liquid film splitting agent that is fluid at room temperature and normal pressure is attached to the skin-facing side of a topsheet (fiber assembly) of an absorbent article, the liquid film splitting agent will migrate to the opposite side (non-skin-facing side) of the topsheet due to its own weight over time, resulting in a deterioration over time of the dryness of the skin-facing side of the topsheet. As a result of further investigation, the present inventors have found that by adjusting the endothermic value of a liquid membrane cleaving agent that has fluidity at room temperature and normal pressure to fall within the above-mentioned specific range, its fluidity is appropriately reduced, and it becomes difficult for the agent to move after adhering to the surface of a fiber. That is, the fiber treating agent has as one of its main objectives the control of the fluidity of compound A that functions as a liquid membrane cleaving agent, and has been developed based on the finding that the endothermic value of the fiber treating agent can be an index of its fluidity. According to the inventors' findings, fiber treatment agents having an endotherm within the above-mentioned specific range typically contain, in addition to a liquid membrane-cleaving agent (e.g., compound A) that is liquid and fluid at room temperature and normal pressure, a non-fluid substance (typically, a minute solid substance with a melting point of 40°C or higher) that has no or poor fluidity at room temperature and normal pressure. The non-fluid substance reduces the fluidity of the liquid membrane-cleaving agent and, ultimately, the fluidity of the entire fiber treatment agent. Compound B, described below, is a specific example of the non-fluid substance. Furthermore, typically, the greater the content of the non-fluid substance in the fiber treatment agent, the lower the fluidity of the fiber treatment agent. When a fiber treatment agent containing such a liquid membrane-cleaving agent and non-fluid substance is heated to melt the non-fluid substance, an endotherm occurs. The endotherm is typically proportional to the content of the non-fluid substance in the fiber treatment agent; the greater the content of the non-fluid substance, the greater the endotherm value of the fiber treatment agent. Therefore, the fluidity of a fiber treatment agent can be evaluated by measuring the endotherm of the fiber treatment agent. The greater the endothermic value of the fiber treatment agent, the less likely it is to move after adhering to the surface of the fiber, and the more likely it is that the fiber treatment agent's effect of improving dryness will be stably exerted for a long period of time.

[0068] When the endothermic value of the fiber treatment agent is 1.1 mJ / mg or more, the fluidity of the fiber treatment agent is not too high, resulting in good durability of dryness over time. When the endothermic value of the fiber treatment agent is 60 mJ / mg or less, the fluidity of the fiber treatment agent is not too low, resulting in avoiding deterioration in the handleability of the fiber treatment agent and facilitating the process of applying the fiber treatment agent to fibers. From the viewpoint of more reliably achieving the desired effect of the fiber treatment agent, i.e., the effect of stably improving the dryness of fibers over a long period of time, the endothermic value of the fiber treatment agent is preferably 1.5 mJ / mg or more, more preferably 2.0 mJ / mg or more, even more preferably 5.0 mJ / mg or more, and preferably 50 mJ / mg or less, more preferably 40 mJ / mg or less, even more preferably 30 mJ / mg or less, and even more preferably 20 mJ / mg or less. The endothermic value of the fiber treatment agent can be adjusted, for example, by adjusting the type and content of the non-fluid substance.

[0069] <Method for measuring endothermic heat> Using a differential scanning calorimeter, the temperature of the object to be measured (fiber-attached material) is raised from -20 to 200°C at a rate of 20°C / min to obtain a DSC curve. In the obtained DSC curve, the calorific value at the endothermic peak appearing between 10 and 180°C is regarded as the endothermic value of the object to be measured. As the differential scanning calorimeter, for example, a "DSC7000X" manufactured by Hitachi High-Tech Corporation can be used.

[0070] The fiber treatment agent has a plastic deformation rate, measured by the following method, of preferably 60% or more, more preferably 65% ​​or more, even more preferably 70% or more, even more preferably 75% or more, even more preferably 80% or more, and even more preferably 85% or more. The plastic deformation rate is an index that indicates the extent to which the displacement (maximum displacement) when a specified load is applied to a sample (fiber treatment agent) returns to its original state after the load is removed, and the larger the value of the plastic deformation rate, the more easily the sample is evaluated to deform when subjected to an external force. As mentioned above, fiber treatment agents with endothermic values ​​within the above-mentioned specific range, i.e., fiber treatment agents with excellent durability over time in the dryness of fibers, typically contain a liquid film-cleaving agent, such as Compound A, that is fluid at room temperature and normal pressure, as well as a non-fluid substance. Depending on the content and distribution of the non-fluid substance, such fiber treatment agents can become "hard fiber treatment agents" that are resistant to deformation even when subjected to external forces. Furthermore, with such hard fiber treatment agents, even when the fiber comes into contact with liquids such as menstrual blood or urine, the liquid film-cleaving agent contained within the hard fiber treatment agent may not flow out, potentially resulting in insufficient liquid film-cleaving effect. In contrast, if the fiber treatment agent has a plastic deformation rate of 60% or more, the fiber treatment agent is easily deformed upon contact with liquid, which makes it easier for the liquid film-cleaving agent contained within the fiber treatment agent to flow out, thereby enabling the liquid film-cleaving effect to be stably achieved. In this way, the plastic deformation rate of the fiber treatment agent is an indicator of the "ease of outflow of the liquid membrane splitting agent (compound A)" ​​when the fiber treatment agent comes into contact with a liquid, and the larger the plastic deformation rate, the more likely the liquid membrane splitting effect will be exhibited. Although there is no particular upper limit to the plastic deformation rate of the fiber treatment agent, from the viewpoint of ensuring that the liquid membrane cleaving agent contained in the fiber treatment agent is slowly released each time excrement such as menstrual blood or urine comes into contact with the fiber treatment agent repeatedly, the upper limit is preferably 95% or less, more preferably 90% or less. The plastic deformation rate of the fiber treatment agent can be adjusted, for example, by adjusting the type and content of the non-fluid substance.

[0071] <Method for measuring plastic deformation rate> Perform the following steps 1 to 3 in order. (Procedure 1) The fiber treatment agent to be measured is placed in an aluminum cup with a circular bottom and an inner diameter of 54 mm in plan view, in an amount such that the thickness of the fiber treatment agent (the distance from the inner surface of the bottom of the aluminum cup to the surface of the fiber treatment agent) is 4 mm. The aluminum cup is placed on the top surface of a horizontal base, and one side (bottom) of an aluminum plate (1.9 mm thick and weighing 2.4 g) with a diameter of 25 mm in plan view and circular in plan view is placed on top of the fiber treatment agent contained in the aluminum cup. If the aluminum plate sinks by 1 mm or more due to its own weight, the plastic deformation rate of the fiber treatment agent is considered to be 100%, and the measurement of the plastic deformation rate is terminated; otherwise, the measurement of the plastic deformation rate is continued. When continuing to measure the plastic deformation rate, the vertical distance (distance before compression) L0 (unit: mm) from the top surface of the base to the top surface of the aluminum plate (the surface opposite to the surface that comes into contact with the contents of the aluminum cup) is measured with a laser meter, and the initial thickness T0 (unit: mm) of the fiber treatment agent is calculated using the following formula. T0 = ​​L0 - (thickness of the bottom of the aluminum cup) - (thickness of the aluminum plate) (Operation 2) After measuring the pre-compression distance L0, if the contents of the aluminum cup (fiber treatment agent) are protruding from the aluminum plate when viewed from above, remove the protruding portion using a spoon or the like. (Step 3) Press the aluminum plate to move it toward the bottom of the aluminum cup by a distance equivalent to T0 x 0.3, then quickly unload it. Then, measure the vertical distance (post-compression distance) L1 (unit: mm) from the top surface of the base to the top surface of the aluminum plate using a laser meter, and calculate the thickness T1 (unit: mm) of the fiber treatment agent after 30% compression using the following formula: T1 = L1 - (thickness of the bottom of the aluminum cup) - (thickness of the aluminum plate) Then, using the above T0 and T1, the deformation rate D1 (unit: %) of the fiber treatment agent after 30% compression is calculated according to the following formula, and further the target plastic deformation rate (unit: %) is calculated. D1 = (T0 - T1) / T0 × 100 Plastic deformation ratio = D1 / 30 x 100

[0072] One embodiment of the fiber treatment agent further contains a compound B having a melting point of 40° C. or higher in addition to compound A. Compound B is a specific example of the non-flowable substance, and is used to adjust the endothermic value of the fiber treatment agent to fall within the specific range, thereby improving the durability of the dry properties of the fiber over time. A fiber treatment agent containing compounds A and B typically has a form in which solid compound B is dispersed in liquid compound A under normal temperature and pressure conditions, and the fiber treatment agent as a whole has fluidity.

[0073] The endothermic heat quantity of compound B measured by the above-mentioned method is preferably 10 mJ / mg or more, more preferably 50 mJ / mg or more, even more preferably 80 mJ / mg or more, and is preferably 350 mJ / mg or less, more preferably 320 mJ / mg or less, from the viewpoint of more reliably achieving the effect of compound B, i.e., the effect of improving the durability of the dryness of the fiber over time by reducing the fluidity of the fiber treatment agent.

[0074] To ensure that the effects of compound B are more reliably achieved, compound B is preferably somewhat hard. Specifically, it is preferable that the hardness value measured by the method described below is relatively large. If compound B itself is too soft, the fluidity of the fiber treatment agent containing it may not be significantly reduced, and the durability of the dryness of the fiber over time may not be sufficiently improved. In other words, the hardness of compound B measured by the method described below can serve as an indicator of the fluidity of the fiber treatment agent containing compound B. From this perspective, the hardness of compound B is preferably 10 or more, more preferably 30 or more, even more preferably 50 or more, and even more preferably 60 or more. On the other hand, there is no particular lower limit for the hardness of compound B, but from the viewpoint of not inhibiting the fluidity of the fiber treatment agent, it is preferably 95 or less, more preferably 92 or less, and even more preferably 90 or less. The hardness of compound B is measured by the method described below.

[0075] <Hardness measurement method> The object to be measured (compound B) is placed in an aluminum cup having a circular bottom in plan view and an inner diameter of 54 mm. The aluminum cup is heated to melt the object to be measured, and then the object is cooled to room temperature. The aluminum cup is removed to prepare a plate-shaped sample of the object to be measured having a thickness of 5 mm. The hardness of the sample is then measured in a conventional manner using a hardness tester A, with the contact surface of the sample with the bottom of the aluminum cup as the measurement surface. If the sample breaks during the process of pressing the hardness tester A against the sample, the measurement value obtained by the hardness tester A at the time of breakage is taken as the hardness of the sample. For example, the "HD-101N" manufactured by Ueshima Seisakusho Co., Ltd. can be used as the hardness tester A.

[0076] The content of compound B in the fiber treatment agent is preferably 0.1% by mass or more, and more preferably 0.2% by mass or more, from the viewpoint of more reliably achieving the effects of compound B. On the other hand, the upper limit of the content of compound B in the fiber treatment agent is preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 9% by mass or less, and even more preferably 7% by mass or less, from the viewpoint of reducing the fluidity of the entire fiber treatment agent and facilitating the outflow of the internal liquid membrane cleaving agent.

[0077] From the viewpoint of improving the durability of the dry properties of the fiber over time, the mass ratio of compound A to compound B in the fiber treatment agent, as compound A / compound B, is preferably 3 or more, more preferably 5 or more, even more preferably 10 or more, still more preferably 14 or more, and is preferably 1000 or less, more preferably 900 or less, even more preferably 700 or less, still more preferably 500 or less.

[0078] Preferred examples of compound B include those belonging to the "first group" below. The fiber treatment agent can contain one or more compounds B selected from the first group. The mass average molecular weight of compound B in the first group is preferably 10,000 or less, more preferably 3,000 or less. The lower limit of the mass average molecular weight of compound B in the first group is preferably 100 or more, more preferably 300 or more. The mass average molecular weight of compound B in the first group can be measured in accordance with the method for measuring the mass average molecular weight of the liquid membrane cleaving agent described above.

[0079] (Compound B of the first group) Solid hydrocarbons, solid aliphatic alcohols and their derivatives, solid fatty acids and their derivatives, solid polyethylene glycols and their derivatives, amino acid derivatives, sugars and their derivatives, sugar alcohols.

[0080] The first group of compounds B will now be further explained. The "solid hydrocarbon" may be, for example, a saturated hydrocarbon preferably having 19 or more carbon atoms, more preferably having 20 or more carbon atoms. Specific examples include solid paraffin. Examples of the "solid aliphatic alcohol" include linear saturated aliphatic alcohols preferably having 12 to 22 carbon atoms, more preferably 14 to 22 carbon atoms, and specific examples include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, arachidyl alcohol, and behenyl alcohol. The "solid aliphatic alcohol derivative" may be, for example, an aliphatic alcohol ethoxylate preferably having 12 to 22 carbon atoms, and a specific example thereof is polyoxyethylene (25) lauryl ether. The "solid fatty acid" preferably includes, for example, saturated fatty acids having from 10 to 22 carbon atoms, more preferably from 12 to 22 carbon atoms, and specific examples include decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid. Examples of the "solid fatty acid derivative" include fatty acid ethylene oxide adducts, polyhydroxy fatty acid amides, polyhydroxy fatty acid esters, and polyhydric alcohol fatty acid esters, preferably having from 12 to 22 carbon atoms, more preferably from 14 to 22 carbon atoms. A specific example of a fatty acid ethylene oxide adduct is polyoxyethylene (40) monostearate. A specific example of a polyhydroxy fatty acid amide is C18 alkyl N-methyl glucamide. A specific example of a polyhydroxy fatty acid ester is polyglyceryl-2 stearate. A specific example of a polyhydric alcohol fatty acid ester is glyceryl (behenate / eicosadioxide). The "solid polyethylene glycol" may be, for example, polyethylene glycol having a mass average molecular weight of 2,000 to 10,000, and specific examples thereof include polyethylene glycol having a mass average molecular weight of 3,000, 6,000, or 8,000. The "solid polyethylene glycol derivative" may be, for example, polyethylene glycol having an addition mole number of 16 or more and 220 or less, and a specific example thereof is polyethylene glycol in which one or both ends of the main chain are protected with a terminal protecting group. The "solid polyethylene glycol derivative" may also be one produced from multiple units of propylene glycol, and may be a mono- or di-ester or ether-terminal protected polyethylene glycol. In the "solid polyethylene glycol derivative," the terminal protecting group may be one or more selected from an alkyl ester group and an alkyl ether group, and specific examples thereof include a methyl group, an ethyl group, and a propyl group. Examples of the "amino acid derivatives" include dibutyl lauroyl glutamide and dibutyl ethyl hexanoyl glutamide. Examples of the "sugar" include raffinose, maltodextrose, galactose, sucrose, glucose, xylose, fructose, maltose, lactose, mannose, and erythrose. Examples of the "sugar derivatives" include glucuronic acid, glucosamine, and deoxyribose. Examples of the "sugar alcohol" include erythritol, xylitol, malitol, mannitol, and sorbitol.

[0081] Other preferred examples of compound B include those belonging to the "second group" below. The fiber treatment agent can contain one or more compounds B selected from the second group. The mass average molecular weight of compound B of the second group is preferably more than 10,000, more preferably 20,000 or more. The upper limit of the mass average molecular weight of compound B of the second group below is preferably 1,000,000 or less, more preferably 500,000 or less. The mass average molecular weight of compound B of the second group can be measured in accordance with the method for measuring the mass average molecular weight of the liquid membrane cleaving agent described above.

[0082] (Second group compound B) Natural polymers, synthetic polymers, or their derivatives that are solid at a product temperature of 40°C.

[0083] The second group of compounds B will now be further explained. The second group of compounds B preferably has a soft segment and a hard segment. The soft segment is a flexible component exhibiting rubber elasticity, and the hard segment is a molecular restraining component (hard segment) that acts as a crosslinking point to prevent plastic deformation. Compound B containing both components is an elastomer that combines hardness and flexibility. When compound B is such an elastomer, the fiber treatment agent containing compound B deforms upon contact with excrement, making it easier for the liquid membrane cleaving agent contained therein to escape to the outside, thereby stably exhibiting the liquid membrane cleaving effect. In compound B, the soft segment and the hard segment are bonded. Here, "bonding" includes a state in which both segments are bonded via a chain extender such as an isocyanate compound, and a state in which the constituent units of both segments are directly bonded to each other.

[0084] Examples of the soft segment include polybutadiene, polyisoprene, ethylene propylene diene rubber, polybutylene acrylate, aliphatic polyether, aliphatic polyester, and silicone. Examples of the hard segment include polystyrene, polyurethane, aliphatic polyester, polyamide, polyoxazoline, polyethylene, polypropylene, and polymethyl methacrylate. Specific examples of the second group of compounds B include styrene butadiene rubber, styrene ethylene butylene styrene rubber, acrylic ester rubber, and urethane rubber.

[0085] The soft segment preferably contains a silicone skeleton. This makes the fiber treatment agent highly flexible and easily deformable, so that when the fiber treatment agent is applied to a nonwoven fabric for an absorbent article, for example, the fiber treatment agent is more likely to exhibit a liquid film disruption effect on excrement when the absorbent article is worn. Soft segments containing a silicone skeleton are typically polymers or oligomers having a siloxane bond (Si-O-Si bond) as the main skeleton and an organic group bonded to a silicon atom. Examples of soft segments containing a silicone skeleton include dimethylpolysiloxane, methylhydrogensiloxane, methylphenylsiloxane, and modified silicones. Examples of the modified silicones include amine-modified silicones, fluorine-modified silicones, alcohol-modified silicones, polyether-modified silicones, epoxy-modified silicones, alkyl-modified silicones, carboxyl-modified silicones, ester-modified silicones, and amide-modified silicones. Examples of compound B having a soft segment and a hard segment containing a silicone skeleton include poly(N-propionylethyleneimine)-modified silicone (described in Synthesis Example 10 of Japanese Patent No. 5751818); acrylic polymer-modified silicone (KP-545, KP-545L, KP-550, KP-543 manufactured by Shin-Etsu Chemical Co., Ltd.); silicone-modified polynorbornene (NBN-30-ID manufactured by Shin-Etsu Chemical Co., Ltd.); and silicone-modified pullulan (TSPL-30-D5 manufactured by Shin-Etsu Chemical Co., Ltd.).

[0086] The mass ratio of the soft segment to the hard segment in the compound B of the second group is not particularly limited, but from the viewpoint of more reliably exhibiting the effects of compound B, the soft segment / hard segment ratio is preferably 0.5 or more, more preferably 0.8 or more, and is preferably 20 or less, more preferably 10 or less. The content of the soft segment in the second group of compounds B is preferably 30% by mass or more, more preferably 50% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, based on the total mass of compound B. The content of the hard segment in the second group of compounds B is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 70% by mass or less, more preferably 50% by mass or less, based on the total mass of compound B. The sum of the soft segment content and the hard segment content is 100% by mass.

[0087] The components of the nonwoven fabric of the present invention other than the fiber treatment agent will be described below. The nonwoven fabric of the present invention is for use in absorbent articles and is used as a constituent member of the absorbent article. The term "absorbent article" as used herein includes articles used to absorb bodily waste (menstrual blood, urine, loose stool, sweat, etc.), such as disposable diapers, sanitary napkins, sanitary shorts, and incontinence pads. The nonwoven fabric of the present invention is particularly useful as a component in an absorbent article that is placed closer to the wearer's skin than the absorbent core. Such components include a topsheet and a second sheet. The topsheet is a component placed in a position in the absorbent article where it can come into contact with the wearer's skin. The second sheet is a component placed between the topsheet and the absorbent core.

[0088] In the nonwoven fabric of the present invention, the fiber treating agent may be present throughout the nonwoven fabric or may be unevenly distributed in some areas, and can be appropriately selected depending on the type of absorbent article to which the nonwoven fabric is applied, the application site of the nonwoven fabric in the absorbent article, etc. For example, when the nonwoven fabric of the present invention is used as a topsheet of an absorbent article, the fiber treating agent may be present only on the skin-facing surface (the surface facing the wearer's skin) in the thickness direction of the topsheet.

[0089] The content of the fiber treating agent in the nonwoven fabric of the present invention may be adjusted appropriately depending on the type of absorbent article to which the nonwoven fabric is applied, the constituent members of the absorbent article to which the nonwoven fabric is applied (e.g., topsheet), etc., and is not particularly limited, but from the viewpoint of ensuring that the liquid film splitting effect of the fiber treating agent is more reliably exhibited, it is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and even more preferably 0.25 mass% or more, relative to the total mass of the nonwoven fabric. On the other hand, the upper limit of the content of the fiber treating agent in the nonwoven fabric of the present invention is also not particularly limited, but from the viewpoint of not impairing the dry feeling when the nonwoven fabric is applied to a constituent member that may come into contact with the wearer's skin in an absorbent article, such as a topsheet, it is preferably 10 mass% or less, more preferably 6 mass% or less, and even more preferably 4 mass% or less. The content of the fiber treatment agent in the nonwoven fabric is calculated as the ratio of the "mass of the fiber attachment" to the total mass of the nonwoven fabric being measured (the mass of the entire nonwoven fabric including attachments such as the fiber treatment agent).

[0090] The nonwoven fabric of the present invention may contain components other than the fiber treatment agent. One example of such components is a phosphate ester-type anionic surfactant. Phospholipids are generally contained in blood and urine, and phosphate ester-type anionic surfactants have a high affinity for these phospholipids. Therefore, when the nonwoven fabric contains such surfactants, the hydrophilicity (wettability) of the fiber surface is improved, which facilitates the migration of the fiber treatment agent (more specifically, compound A contained in the fiber treatment agent) into the liquid film and promotes the rupture of the liquid film. The phosphate ester-type anionic surfactant that can be contained in the nonwoven fabric of the present invention is not particularly limited, and examples thereof include alkyl ether phosphate esters, dialkyl phosphate esters, and alkyl phosphate esters. Among these, alkyl phosphate esters are preferred from the viewpoint of enhancing affinity with liquid membranes and at the same time imparting processability to the nonwoven fabric.

[0091] The nonwoven fabric of the present invention preferably has a contact angle of 90 degrees or less, more preferably 80 degrees or less, and even more preferably 70 degrees or less of the constituent fibers. This makes the fiber surface hydrophilic, increasing the wetted area and facilitating the transfer of the fiber treatment agent to the liquid film. The contact angle is measured by the following method.

[0092] <Contact angle measurement method> Fibers are removed from a designated location on the nonwoven fabric, and the contact angle of water with the fibers is measured. The measurement device used is an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. Distilled water is used for contact angle measurements. Measurement conditions are a temperature of 25°C and a relative humidity (RH) of 65%. The amount of liquid ejected from the inkjet water droplet ejection unit (CTC-25 pulse injector with a 25μm nozzle diameter manufactured by Cluster Technology Co., Ltd.) is set to 20 picoliters, and the water droplets are dropped directly onto the fibers. The dropping behavior is recorded on a high-speed recording device connected to a horizontally placed camera. For later image analysis and analysis, a personal computer equipped with a high-speed capture device is preferable. In this measurement, images are recorded every 17 msec. In the recorded video, the first image of a water droplet landing on a fiber removed from the nonwoven fabric is analyzed using the accompanying software FAMAS (software version 2.6.2, analysis method as sessile drop method, analysis method as θ / 2 method, image processing algorithm as non-reflective, image processing image mode as frame, threshold level as 200, no curvature correction), and the angle between the surface of the water droplet in contact with the air and the fiber is calculated, which is taken as the contact angle. The fiber removed from the nonwoven fabric is cut to a fiber length of 1 mm and placed on the sample stage of the contact angle meter, maintaining it horizontally. The contact angle is measured at two different points for each fiber. The contact angles of N=5 fibers are measured to one decimal place, and the average value (rounded to two decimal places) of the measured values ​​at a total of 10 points is defined as the contact angle.

[0093] In the nonwoven fabric of the present invention, the fiber diameter of the constituent fibers is not particularly limited. Generally, to obtain a nonwoven fabric that is soft to the touch, it is effective to reduce the fiber diameter of the constituent fibers, i.e., to use thin fibers as the constituent fibers. However, when thin fibers are used, the interfiber distance becomes small, resulting in more narrow areas between the fibers, which may lead to concerns about liquid residue. However, the nonwoven fabric of the present invention contains a fiber treatment agent, which eliminates such concerns. Therefore, by reducing the fiber diameter of the constituent fibers, it is possible to prevent liquid residue while improving the texture. In the nonwoven fabric of the present invention, the fiber diameter of the constituent fibers is preferably 3 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 20 μm or less.

[0094] The constituent fibers of the nonwoven fabric of the present invention can be any fibers conventionally used as constituent fibers of nonwoven fabrics, and examples thereof 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 or two or more types of fibers as constituent fibers. The nonwoven fabric of the present invention is typically composed primarily 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 core-sheath or side-by-side composite fibers, split fibers, modified cross-section fibers, heat-shrinkable fibers, etc. The composite fibers may be composed of multiple resin components.

[0095] The nonwoven fabric of the present invention may have a single layer structure or a laminate structure in which two or more layers are laminated in the thickness direction.

[0096] The nonwoven fabric of the present invention may be a so-called uneven nonwoven fabric having a plurality of convex portions and concave portions located between the convex portions formed on at least one surface thereof. When the nonwoven fabric of the present invention is an uneven nonwoven fabric, the uneven nonwoven fabric is usually arranged in an absorbent article so that the uneven surface of the uneven nonwoven fabric faces the skin.

[0097] Regardless of the form (layer structure, presence or absence of irregularities, etc.) of the nonwoven fabric of the present invention, it is preferable that a fiber treatment agent be present at least on the skin-facing surface, from the viewpoint of ensuring that the effect of the nonwoven fabric (the effect of stably exhibiting a high level of dryness for a long period of time) is exhibited.

[0098] A preferred embodiment of the nonwoven fabric of the present invention includes an air-through nonwoven fabric or a spunbond nonwoven fabric. The "air-through nonwoven fabric" refers to a nonwoven fabric produced by a process (air-through treatment process) in which a fluid (e.g., gas or steam) at 50°C or higher is sprayed onto a fiber web or nonwoven fabric. The "spunbond nonwoven fabric" refers to a laminated nonwoven fabric produced by the spunbond method. These nonwoven fabrics have excellent feel against the skin, and the nonwoven fabric of the present invention containing these nonwoven fabrics, combined with the high level of dryness provided by the fiber treatment agent, can further improve the wearing comfort of absorbent articles. The nonwoven fabric of the present invention may be composed solely of an air-through nonwoven fabric or a spunbond nonwoven fabric, may contain both nonwoven fabrics, or may contain one or both of these nonwoven fabrics in addition to another nonwoven fabric.

[0099] One embodiment of the nonwoven fabric of the present invention is a textured nonwoven fabric containing thermoplastic fibers as its constituent fibers. Specific examples of the textured nonwoven fabric include nonwoven fabric 10 (see Figure 3 in Patent Document 1), nonwoven fabric 20 (see Figure 4 in Patent Document 1), nonwoven fabric 30 (see Figure 5 in Patent Document 1), nonwoven fabric 40 (see Figures 6 and 7 in Patent Document 1), nonwoven fabric 50 (see Figures 8 and 9 in Patent Document 1), nonwoven fabric 60 (see Figure 10 in Patent Document 1), and nonwoven fabric 70 (see Figure 11 in Patent Document 1). The nonwoven fabric of the present invention may have the same configuration as any one of nonwoven fabrics 10 to 70, except for the fiber treatment agent.

[0100] The basis weight of the nonwoven fabric of the present invention is not particularly limited, but as a constituent member of an absorbent article, it is preferably 10 g / m 2 More than 100g / m 2 Less than 15 g / m, more preferably 2 More than 80g / m 2 The following is the result.

[0101] The nonwoven fabric of the present invention can be produced using a conventional method for producing a nonwoven fabric in which a liquid agent is adhered to the surface of the constituent fibers at room temperature and normal pressure. The method for producing the nonwoven fabric of the present invention may involve impregnating a nonwoven fabric that does not contain a fiber-treating agent with a fiber-treating agent, or it may involve pretreating fibers that do not contain a fiber-treating agent (pretreatment) to impregnate them with a fiber-treating agent to obtain pretreated fibers, and then producing a nonwoven fabric using the pretreated fibers in a conventional manner. The production of a nonwoven fabric using the pretreated fibers typically proceeds in the order of producing a fiber web and then forming the fiber web into a nonwoven fabric. The fiber web can be produced using a conventional fiber web production method, such as carding, air-laid, or spunbonding. The fiber web can be formed into a nonwoven fabric using a conventional nonwoven fabric production method, such as spunlace, needle punching, chemical bonding, or dot embossing.

[0102] The method for incorporating the fiber treatment agent into the fibers or nonwoven fabric is not particularly limited, and examples thereof include a method of immersing the fibers or nonwoven fabric in a treatment liquid containing the fiber treatment agent. Another method includes a method of applying the fiber treatment agent or a treatment liquid containing the same to the fibers or nonwoven fabric. The latter application method can be any conventionally known application method without particular limitation, and examples thereof include application by spraying, application by a slot coater, application by roll transfer such as gravure, flexography, or gate roll, and application by dipping.

[0103] The treatment liquid can be a mixture of a fiber treatment agent and a liquid medium. The liquid medium is preferably one that can adequately dissolve or disperse the fiber treatment agent to emulsify it. Examples of liquid media (i.e., solvents) that can dissolve the fiber treatment agent include organic solvents such as ethanol, methanol, acetone, and hexane. When the treatment liquid is an emulsion, for example, water is used as the liquid medium, and, if necessary, various surfactants such as alkyl phosphate esters, fatty acid amides, alkyl betaines, and sodium alkyl sulfosuccinates may be used in combination as emulsifiers. When the nonwoven fabric of the present invention contains components other than the fiber treatment agent (e.g., the phosphate ester-type anionic surfactant), the other components may be contained in the treatment liquid.

[0104] The present invention includes a method for using the fiber treatment agent described above. The method for using the fiber treatment agent of the present invention includes at least one of the following steps 1 and 2: Step 1: Immerse the fiber or nonwoven fabric in a treatment solution containing a fiber treatment agent. Step 2: A fiber treatment agent or a treatment liquid containing the fiber treatment agent is applied to the fiber or nonwoven fabric. The "treatment liquid" in steps 1 and 2 is as described above. According to the method for using the fiber treatment agent of the present invention, a nonwoven fabric for absorbent articles that can stably exhibit a high level of dryness for a long period of time can be obtained.

[0105] 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.

[0106] <1> A nonwoven fabric for absorbent articles in which a fiber treatment agent is attached to the surface of the constituent fibers, The fiber treatment agent contains a compound A that satisfies the following (1) to (4): The nonwoven fabric for absorbent articles has an endothermic value of 1.1 mJ / mg or more and 60 mJ / mg or less of the fiber treatment agent. (1) The expansion coefficient for a liquid with a surface tension of 50 mN / m is greater than 0 mN / m and less than or equal to 50 mN / m. (2) The water solubility is 0 g or more and 0.025 g or less. (3) The interfacial tension with a liquid having a surface tension of 50 mN / m is 20 mN / m or less. (4) The melting point is less than 40°C. <2> The plastic deformation rate of the fiber treatment agent is 60% or more. <1> The nonwoven fabric for absorbent articles according to claim 1. <3> The content of the compound A in the fiber treatment agent is 75.0% by mass or more and 99.9% by mass or less. <1> or <2> The nonwoven fabric for absorbent articles according to claim 1.

[0107] <4> The fiber treatment agent further contains a compound B having a melting point of 40° C. or higher. <1> ~ <3> 10. The nonwoven fabric for absorbent articles according to claim 1. <5> the endothermic amount of the compound B is 10 mJ / mg or more and 350 mJ / mg or less; <4> The nonwoven fabric for absorbent articles according to claim 1. <6> The hardness of the compound B is 10 or more. <4> or <5> The nonwoven fabric for absorbent articles according to claim 1. <7> The content of the compound B in the fiber treatment agent is 0.1% by mass or more and 25% by mass or less. <4> ~ <6> 10. The nonwoven fabric for absorbent articles according to claim 1. <8> The mass ratio of the compound A to the compound B in the fiber treatment agent is 3 or more and 1000 or less, in terms of compound A / compound B. <4> ~ <7> 10. The nonwoven fabric for absorbent articles according to claim 1. <9> The compound A is at least one selected from the group consisting of a silicone compound, a polyether compound, a hydrocarbon compound having 5 to 18 carbon atoms, a saturated fatty acid of C9 or less, and an unsaturated fatty acid of C22 or less. <1> ~ <8> 10. The nonwoven fabric for absorbent articles according to claim 1. <10> The compound B is at least one selected from the group consisting of solid hydrocarbons, solid aliphatic alcohols and derivatives thereof, solid fatty acids and derivatives thereof, solid polyethylene glycols and derivatives thereof, and amino acid derivatives. <4> ~ <9> 10. The nonwoven fabric for absorbent articles according to claim 1. <11> The compound A is a silicone compound, and the compound B is an amino acid derivative. <4> ~ <10> 10. The nonwoven fabric for absorbent articles according to claim 1.

[0108] <12> The constituent fibers include thermoplastic fibers, A plurality of convex portions and concave portions located between the convex portions are formed on at least one surface of the nonwoven fabric for absorbent articles. <1> ~ <11> 10. The nonwoven fabric for absorbent articles according to claim 1. <13> The content of the fiber treatment agent is 0.1% by mass or more. <1> ~ <12> 10. The nonwoven fabric for absorbent articles according to claim 1. <14> The endothermic amount is 2.0 mJ / mg or more and 25 mJ / mg or less. <1> ~ <13> 10. The nonwoven fabric for absorbent articles according to claim 1. <15> The spreading coefficient for a liquid having a surface tension of 50 mN / m is preferably 3 mN / m or more, more preferably 10 mN / m or more, even more preferably 15 mN / m or more, still more preferably 20 mN / m or more, and particularly preferably 25 mN / m or more. <1> ~ <14> 10. The nonwoven fabric for absorbent articles according to claim 1. <16> The interfacial tension with respect to a liquid having a surface tension of 50 mN / m is preferably 17 mN / m or less, more preferably 13 mN / m or less, even more preferably 10 mN / m or less, even more preferably 9 mN / m or less, and particularly preferably 1 mN / m or less. <1> ~ <15> 10. The nonwoven fabric for absorbent articles according to claim 1. [Example]

[0109] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0110] [Examples 1 to 9, Comparative Examples 1 and 2] A fiber treatment agent was prepared by the following method, and a nonwoven fabric for absorbent articles was produced using the fiber treatment agent. Specifically, fibers that serve as raw materials for the nonwoven fabric were pretreated with the fiber treatment agent to obtain pretreated fibers, and nonwoven fabric was produced using the pretreated fibers according to a conventional method. The pretreatment involved immersing the fibers in the fiber treatment agent and then drying the fibers. The nonwoven fabric produced was a textured nonwoven fabric similar to the nonwoven fabric 10 described in Patent Document 1 (see Figure 3 therein), and was produced according to the contents of paragraphs

[0032] to

[0048] of Japanese Patent Laid-Open Publication No. 2002-187228. The textured nonwoven fabric had a laminated structure of a first layer containing non-heat-shrinkable fibers and a second layer in which heat-shrinkable fibers had exhibited heat shrinkage, and these two layers were joined via a joint formed by embossing (compression) from the first layer side to the second layer side, and the surface of the first layer (the surface opposite to the surface facing the second layer) was a textured surface having a plurality of recesses corresponding to the joint and a plurality of protrusions where the joint was not formed. The basis weight of the first layer was 33 g / m 2 The second layer has a basis weight of 41 g / m 2 The constituent fibers of the first layer were sheath-core composite fibers (fiber diameter 17 μm, contact angle measured by the above method 94 degrees) with a polyester core and a polyethylene sheath, and the constituent fibers of the second layer were sheath-core composite fibers (fiber diameter 18 μm, contact angle measured by the above method 81 degrees) with a polyethylene core and a polypropylene sheath. The pretreatment was applied only to the constituent fibers of the first layer, and not to the constituent fibers of the second layer.

[0111] (Method for preparing fiber treatment agent) The components shown in Table 1 below were mixed to prepare fiber treatment agents that were liquid at room temperature and normal pressure. Specifically, compound A and compound B, or compound A alone, were added to, mixed with, and dissolved in a liquid medium to prepare the fiber treatment agents. As the liquid medium, isopropyl alcohol was used in Examples 1 and 4 to 9 and Comparative Examples 1 and 2, and hexane was used in Examples 2 and 3. When compound A or B was difficult to dissolve in the liquid medium, the liquid medium was heated to 50°C or higher to promote dissolution. Details of compounds A and B are as follows:

[0112] (Component A) Compound A1: PPG-15 stearyl ("MS-70K" manufactured by NOF Corporation). Compound A1 is a type of the polyether compound (liquid membrane cleaving agent) and has a mass average molecular weight of 1,140. Compound A2: POE-modified silicone (PEG-3 dimethicone) ("KF-6015" manufactured by Shin-Etsu Chemical Co., Ltd.). Compound A2 is a type of the silicone compound (liquid membrane cleaving agent) and has a mass average molecular weight of 4,000.

[0113] (Component B) Compound B1: Polyoxyethylene (40) monostearate (polyoxyl 40 stearate) ("EMALEX840" manufactured by Nippon Emulsion Co., Ltd.) Compound B1 is one of the compounds B in the first group. Compound B2: Paraffin wax ("Paraffin Wax 155" manufactured by Nippon Seiro Co., Ltd.) Compound B2 is one of the compounds B in the first group, and has a mass average molecular weight of 550. Compound B3: Glyceryl (behenate / eicosapentaenoate) ("Nomcort HK-G" manufactured by Nisshin Oillio Group, Ltd.) Compound B3 is one of the compounds B in the first group. Compound B4: behenyl alcohol ("Kalcol 220-80" manufactured by Kao Corporation). Compound B4 is one of the compounds B in the first group, and has a mass average molecular weight of 327. Compound B5: dibutyl lauroyl glutamide ("GP-1" manufactured by Ajinomoto Co., Inc.). Compound 5 is a type of compound B in the first group, and has a mass-average molecular weight of 438.

[0114] [Evaluation test] The amount of residual liquid was evaluated for the nonwoven fabrics of each of the Examples and Comparative Examples by the following method, and the results are shown in Table 1 below.

[0115] <Method for evaluating remaining liquid amount> Two types of nonwoven fabric were prepared for evaluation: one immediately after production (referred to in Table 1 as "immediately after application of fiber treatment agent"), and one that had been stored in an environment with an ambient temperature of 40°C for one month after production (referred to in Table 1 as "one month after application of fiber treatment agent"). The top sheet was removed from a sanitary napkin (Kao Corporation: Laurier Shiawase Suhada Fluffy Type 22.5 cm, manufactured in 2022), and instead the nonwoven fabric to be evaluated was placed horizontally with the side that will face the skin when incorporated into an absorbent article (the side on the first layer side) facing up.A rectangular weight weighing 2 kg and with a base of 6.5 cm short sides and 9.5 cm long sides was placed on top of the nonwoven fabric with the long side aligned with the longitudinal direction of the product, and the weight was removed to prepare a sanitary napkin for evaluation. The center of the sanitary napkin for evaluation had a minor axis radius of 1.12 cm, a major axis radius of 2.50 cm, and an area of ​​8.8 cm 2 An oval acrylic cylinder was placed on the cylinder so that the longitudinal direction of the product was the major axis. 3.0 g of sterile defibrated equine blood equivalent to menstrual blood (sterile defibrated equine blood manufactured by Japan Biomaterials Center Co., Ltd., adjusted to 24.0 cP) was injected into the cylinder all at once. The viscosity of the horse blood used was adjusted using a Toki Sangyo TVB10 viscometer with rotor No. 20, rotor M1, and 12 rpm. When horse blood is left to stand, the high-viscosity portion (red blood cells, etc.) precipitates, while the low-viscosity portion (plasma) remains as the supernatant. The mixing ratio of these portions was adjusted to 24.0 cP. One minute after injection, the horse blood adhering to the inside of the cylinder was absorbed with tissue, the cylinder was removed, and a 13 g / m2 grammage blood sample was placed in the center of the product. 2A rectangular weight weighing 125 g, with a base of 3.0 cm and a length of 10.5 cm, was placed on top of the absorbent paper (16 sheets of commercially available tissue paper stacked together), with the long side aligned with the longitudinal direction of the product, and pressure was applied for 1 minute. After 1 minute, the weight and absorbent paper were removed. After 2 minutes, the cylinder was placed again in the center of the sanitary napkin for evaluation that had undergone the above series of operations, and the same operation was repeated (after injecting 3.0 g of horse blood, a new absorbent paper and the 125 g weight were placed on top, and pressure was applied for 1 minute. After 1 minute, the weight and absorbent paper were removed). The amount of horse blood adhering to the absorbent paper used in the second operation was calculated from the difference in weight of the absorbent paper before and after absorption, and this was taken as the residual liquid amount. The above operation was performed three times, and the average of the three values ​​was taken as the residual liquid amount (mg) of the nonwoven fabric. The smaller the residual liquid amount value, the better the dryness of the nonwoven fabric and the higher the evaluation.

[0116] [Table 1]

[0117] As shown in Table 1, the fiber treatment agent adhered to the constituent fibers of the nonwoven fabric of each Example contains, in addition to Compound A, which functions as a liquid film cleaving agent, Compound B, which is solid in an ambient temperature of 40°C or higher. Due to Compound B, the endothermic heat of the fiber treatment agent is in the range of 1.1 mJ / mg to 60 mJ / mg. In contrast, the fiber treatment agent adhered to the constituent fibers of the nonwoven fabric of Comparative Example 1 does not contain Compound B, and the endothermic heat of the fiber treatment agent is less than 1.1 mJ / mg. Furthermore, the fiber treatment agent adhered to the constituent fibers of the nonwoven fabric of Comparative Example 2 has an endothermic heat of more than 60 mJ / mg. Due to these differences between the Examples and Comparative Examples, the nonwoven fabrics of the Examples had a smaller amount of remaining liquid "one month after application of the fiber treatment agent" than the nonwoven fabric of the Comparative Examples. From this, it can be seen that in order to obtain a fiber treatment agent that can stably increase the dryness of fibers for a long period of time and is suitable for nonwoven fabrics for absorbent articles, it is effective to add compound B to a fiber treatment agent containing a liquid membrane cleaving agent (compound A) and adjust the endothermic value of the fiber treatment agent to fall within the above range. [Explanation of symbols]

[0118] 1. Fiber 2 Liquid film 3. Fiber treatment agents

Claims

1. A nonwoven fabric for absorbent articles in which a fiber treatment agent is attached to the surface of the constituent fibers, The fiber treatment agent contains a compound A that satisfies the following (1) to (4): The nonwoven fabric for absorbent articles has an endothermic value of 1.1 mJ / mg or more and 60 mJ / mg or less of the fiber treatment agent. (1) The expansion coefficient for a liquid with a surface tension of 50 mN / m is greater than 0 mN / m and not greater than 50 mN / m. (2) The water solubility is 0 g or more and 0.025 g or less. (3) The interfacial tension with respect to a liquid having a surface tension of 50 mN / m is 20 mN / m or less. (4) The melting point is less than 40°C.

2. 2. The nonwoven fabric for absorbent articles according to claim 1, wherein the fiber treatment agent has a plastic deformation rate of 60% or more.

3. The nonwoven fabric for absorbent articles according to claim 1 or 2, wherein the content of the compound A in the fiber treatment agent is 75.0% by mass or more and 99.9% by mass or less.

4. The nonwoven fabric for absorbent articles according to claim 1 or 2, wherein the fiber treatment agent further contains a compound B having a melting point of 40°C or higher.

5. The nonwoven fabric for absorbent articles according to claim 4, wherein the compound B has an endothermic amount of 10 mJ / mg or more and 350 mJ / mg or less.

6. The nonwoven fabric for absorbent articles according to claim 4 , wherein the hardness of the compound B is 10 or more.

7. The nonwoven fabric for absorbent articles according to claim 4 , wherein the content of the compound B in the fiber treatment agent is 0.1% by mass or more and 25% by mass or less.

8. 5. The nonwoven fabric for absorbent articles according to claim 4, wherein the mass ratio of the compound A to the compound B in the fiber treatment agent is 3 or more and 1,000 or less, in terms of compound A / compound B.

9. The constituent fibers include thermoplastic fibers, 3. The nonwoven fabric for absorbent articles according to claim 1, wherein a plurality of convex portions and concave portions located between the convex portions are formed on at least one surface of the nonwoven fabric for absorbent articles.

10. The nonwoven fabric for absorbent articles according to claim 1 or 2, wherein the content of the fiber treatment agent is 0.1% by mass or more.

Images