Nonwoven fabric, nonwoven fabric for wiping cloth base material, and wiping cloth

Abstract

The present invention provides a wiping cloth that exhibits excellent dirt-collecting properties, allows for wiping and drying with light force, and leaves minimal liquid residue when used impregnated with liquid. [Solution] A nonwoven fabric comprising a fiber layer X1 containing 10% to 90% by mass of fibers derived from irregularly shaped cross-sectional fibers having multiple protrusions in their cross-section, and 10% to 90% by mass of fibers A made of thermoplastic resin, wherein when the total number of fibers A in the fiber layer X1 is taken as 100%, the fiber layer X1 contains fibers A1 to A3, each with a different cross-sectional area, in a predetermined proportion, and the fibers are integrated together by entanglement.

Description

Technical Field

[0001] The present disclosure relates to non-woven fabrics, non-woven fabrics for wiping cloth substrates, and wiping cloths.

Background Art

[0002] Non-woven fabrics exhibit various characteristics depending on the type of fibers that constitute them, and are applied to various uses by utilizing such characteristics. For example, when a non-woven fabric is constituted of fibers including ultrafine fibers generated by splitting of split-type composite fibers, it is known that the non-woven fabric is dense and has a smooth surface. It is also known to constitute a non-woven fabric with fibers having a non-circular cross-sectional shape. In a non-woven fabric using fibers having a non-circular cross-sectional shape, in addition to the voids formed between the fibers, voids derived from the cross-sectional shape of the fibers are formed on the fiber side surfaces, and thus such a non-woven fabric has a higher bulkiness compared to a non-woven fabric constituted of fibers having a circular cross-section with the same fineness.

[0003] As one of the uses of non-woven fabrics using the ultrafine fibers and fibers having a non-circular cross-sectional shape, a wiping cloth for wiping dirt from an object or wiping dirt off an object has been proposed. For example, Patent Document 1 discloses a wiping cloth in which a short fiber web layer is laminated on both sides of a cotton layer mainly composed of cotton linter or cotton fibers, the short fiber web layer is composed of liquid-absorbent fibers, non-circular cross-sectional fibers, and ultrafine fibers, and these constituent fibers are integrated by entanglement with each other, and the cotton layer and the short fiber web layer are laminated and integrated by entanglement of the fibers constituting both layers. Patent Document 2 proposes a wiping sheet including a non-woven fabric containing non-circular cross-sectional fibers in which the fibers are entangled without being fused, the tensile strength of the non-woven fabric is 80 N / 30 mm or more and 200 N / 30 mm or less, and the amount of fiber shedding indicating the degree of freedom of the fibers is 2 mg or more and 50 mg or less.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2006-316361 [Patent Document 2] Japanese Patent Publication No. 2019-97589 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of this disclosure is to provide a nonwoven fabric that exhibits unprecedented properties by combining irregularly shaped cross-sectional fibers with a plurality of thermoplastic resin fibers having different cross-sectional shapes and areas, thereby creating various voids in the nonwoven fabric, and making it suitable for various applications, such as wiping cloths. [Means for solving the problem]

[0006] One form of nonwoven fabric relating to this disclosure is, A nonwoven fabric comprising a fiber layer X1 containing 10% to 90% by mass of fibers derived from irregularly shaped cross-section fibers having at least multiple protrusions in their cross-sectional surface, and 10% to 90% by mass of fibers A made of thermoplastic resin (excluding the aforementioned irregularly shaped cross-section fibers), The fiber A comprises a plurality of fibers with different fiber cross-sectional shapes and areas. When the total number of fibers A in the fiber layer X1, as measured by the following method, is taken as 100%, the fiber layer X1 contains the following fibers A1 to A3 as fiber A, in the following proportions: It is a nonwoven fabric in which the fibers are fused together by entanglement. (i) Fiber A1 having a fiber cross-sectional area less than 0.25 times the maximum fiber cross-sectional area Smax of fiber A: 20% to 85%. (ii) Fiber A2 having a fiber cross-sectional area of ​​0.25 times or more and 0.5 times or less than the maximum fiber cross-sectional area Smax of fiber A: 5% to 60%. (iii) Fiber A3 having a fiber cross-sectional area greater than 0.5 times and less than or equal to 1 time the maximum fiber cross-sectional area Smax of fiber A: 10% to 70%. [Method for measuring the number of fibers A in fiber layer X1] (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) From the captured image, count the number of fibers A and measure the fiber cross-sectional area using the image analysis software "Micro Measure".

[0007] Another form of nonwoven fabric relating to this disclosure is, The fiber layer X1 comprises 10% to 90% by mass of fibers derived from irregularly shaped cross-section fibers having at least multiple protrusions in their cross-section, and 10% to 90% by mass of fibers derived from segmented composite fibers. The fibers derived from the aforementioned split-type composite fibers include partially split fibers. It is a nonwoven fabric in which the fibers are fused together by entanglement.

[0008] One embodiment of the method for manufacturing nonwoven fabrics relating to this disclosure is: To produce a fiber web containing 10% to 90% by mass of irregularly shaped cross-section fibers having multiple protrusions in their cross-section, and 10% to 90% by mass of segmented composite fibers. The method for manufacturing a nonwoven fabric includes subjecting the aforementioned fiber web to an entanglement treatment using a high-pressure fluid flow of 1 MPa to 10 MPa to cause the fibers to become entangled with each other. [Effects of the Invention]

[0009] The nonwoven fabric of this disclosure includes a fiber layer containing irregularly shaped cross-sectional fibers having a specific fiber cross-sectional shape, and a plurality of fibers with different cross-sectional areas, each in a predetermined proportion, wherein the fibers are integrated by entanglement. With this configuration, various forms of voids are formed in the nonwoven fabric, and among the fibers with different cross-sectional areas, the fibers with smaller cross-sectional areas make the nonwoven fabric dense. As a result, it is possible to achieve a bulky yet smooth surface and appropriate mechanical strength suitable for practical use of the nonwoven fabric. [Brief explanation of the drawing]

[0010] [Figure 1]Figure 1 is a schematic cross-sectional view showing an example of irregularly shaped cross-sectional fibers contained in the nonwoven fabric of the present disclosure. [Figure 2] This is a plan view showing a meandering first entanglement portion in an example of the nonwoven fabric of this embodiment. [Figure 3] This is an SEM image (magnification 100x) of the surface of the nonwoven fabric in this embodiment. [Modes for carrying out the invention]

[0011] Fibers with a non-circular cross-section, i.e., irregularly shaped cross-section fibers, have multiple protrusions in their cross-section, such as triangular, W-shaped, cross-shaped, or multi-lobed sections, and the fiber itself has voids between the protrusions. By utilizing this, the bulk of the nonwoven fabric can be increased, and the strength of the nonwoven fabric can be increased to a certain extent through the engagement of the protrusions. In addition, when the nonwoven fabric is used as a wiping cloth, the protrusions of the irregularly shaped cross-section fibers also function as parts that scrape off dirt.

[0012] On the other hand, fibers other than irregularly shaped cross-section fibers, such as ultrafine fibers produced by splitting a split composite fiber, have a non-circular cross-section and a small surface area, making nonwoven fabrics denser and smoother, thus improving their adhesion to objects. For this reason, ultrafine fibers are also used as fibers that make up nonwoven fabrics for cleaning cloths.

[0013] The inventors hypothesized that by combining irregularly shaped cross-section fibers and ultrafine fibers, a nonwoven fabric with unprecedented properties could be obtained in which the characteristics of both fibers are simultaneously expressed, potentially yielding a nonwoven fabric useful for wiper applications, for example. Therefore, they investigated nonwoven fabrics made from this combination. However, when these were combined, the characteristics of the ultrafine fibers tended to be more pronounced, while the characteristics of the irregularly shaped cross-section fibers were less pronounced, making it difficult to fully express the properties of both. As a result of further investigation, they discovered that by using not only ultrafine fibers completely separated into their individual components in the divided composite fiber, but also fibers with a larger cross-sectional area and a smaller cross-sectional area than the irregularly shaped cross-section fibers, the characteristics of both the irregularly shaped cross-section fibers and the ultrafine fibers were expressed, resulting in a nonwoven fabric with the following overall characteristics. (i) It is bulky. (ii) The surface is smooth, but does not adhere excessively to the object. (iii) Various voids are formed, including voids formed between the protrusions of irregularly shaped cross-section fibers, and fine voids formed by multiple fibers with different cross-sectional areas, including ultrafine fibers. (iv) The striated voids between the fibers of a bundle of ultrafine fibers are similar in structure to the striated recesses formed between the convex portions of irregularly shaped cross-section fibers. Therefore, properties that are exhibited due to both the shape of the ultrafine fiber bundle and the shape of the irregularly shaped cross-section fibers tend to be more easily obtained. (v) It has moderate mechanical strength and the stress during tensile stress does not become excessively high.

[0014] When a nonwoven fabric having the above characteristics is used, for example, as a wiping cloth, (a) It has excellent dirt-scraping properties due to fibers derived from irregularly shaped cross-section fibers, and can also collect the wiped-off dirt, (b) Multiple fibers having a smaller cross-sectional area than irregularly shaped fibers and having different cross-sectional areas from one another are suitable for wiping away fine dirt without damaging mirror-finished objects, and also facilitate the absorption of liquid from the surface of the object by capillary action, making it less likely for liquid to remain. This becomes possible.

[0015] Furthermore, recently, products have been offered in which, along with surfactants, nonwoven fabrics are impregnated with wiping agents such as cleaning agents for object applications and cleansing agents for human applications to remove dirt from objects; products that are pre-impregnated with antibacterial agents or polishing agents for object applications and finishing agents such as cosmetics for human applications to apply finishing agents to objects; or products that combine these functions. When applying finishing agents, the process of applying the finishing agent to the surface of an object using a nonwoven fabric impregnated with the finishing agent is also called "wiping." If strong force is applied during wiping, the finishing agent will be released at the beginning of the process, making it difficult to apply the finishing agent uniformly to the surface of the object. Therefore, it is desirable that the nonwoven fabric used for wiping allows for wiping with light force. The nonwoven fabric with the above configuration is less likely to adhere strongly to the object as seen in nonwoven fabrics using ultrafine fibers, and at the same time exhibits the wiping properties of (a) and (b) above, it is possible to wipe with light force. The nonwoven fabric of this embodiment will be described below.

[0016] The nonwoven fabric of this embodiment is a nonwoven fabric comprising a fiber layer X containing irregularly shaped cross-section fibers having a specific shape in their fiber cross-section (hereinafter also referred to as "fiber cross-section" or "cross-section") and / or fibers derived from said irregularly shaped cross-section fibers, and fibers A made of thermoplastic resin (excluding the aforementioned irregularly shaped cross-section fibers), wherein the fibers A1 have a fiber cross-section area of ​​less than 0.25 times the maximum fiber cross-section area Smax of fiber A, fibers A2 have a fiber cross-section area of ​​0.25 times or more and 0.5 times or less, and fibers A3 have a fiber cross-section area of ​​more than 0.5 times and 1 time or less, and the fibers are integrated by entanglement. First, the fibers constituting the fiber layer X will be described.

[0017] (Irregularly shaped cross-section fibers) The irregularly shaped cross-section fibers included in the nonwoven fabric of this embodiment are fibers having a cross-sectional shape with at least three protrusions in the cross-section of the fiber. The irregularly shaped cross-section fibers will be described with reference to Figure 1. The irregularly shaped cross-section fiber 1 has a multi-lobed shape in the cross-section of the fiber, with three or more protrusions 2.

[0018] When irregularly shaped cross-section fibers, together with fiber A (described later), constitute the fiber layer X1, they exist between the ultrafine fibers derived from the segmented composite fibers, acting as a "framework." This increases the bulk of the nonwoven fabric, enabling wiping and rinsing with light force, and also improves the strength of the nonwoven fabric. This framework role is more pronounced when the fiber strength and fiber diameter of the irregularly shaped cross-section fibers are greater than those of fibers A1 to A3. In addition to their framework role, the irregularly shaped cross-section fibers are also excellent at scraping dirt from the surface of objects and trapping and retaining it due to the convex shape of their cross-section, contributing to improved dirt removal along with the ultrafine fibers derived from the segmented composite fibers.

[0019] Of the protrusions present on the fiber cross-section of the irregularly shaped fiber, at least one protrusion 2 may have a substantially curved tip, and the width Wb of the root portion toward the center of the fiber may be smaller than the maximum width Wt of the tip portion. The number of protrusions 2 is preferably 3 to 8, more preferably 3 to 6, and particularly preferably 3 or 4.

[0020] In irregularly shaped cross-section fibers, if the width Wb of the base portion of the convex portion 2 present on the cross-section of the fiber is smaller than the maximum width Wt of the tip portion, the convex portion 2 becomes more easily deformed. As described later, when manufacturing nonwoven fabrics, force is applied to the fibers during the manufacturing process (for example, the carding process and the water flow entanglement treatment process for water flow entangled nonwoven fabrics), and due to the applied force, at least a portion of the convex portion may be separated or peeled off from the irregularly shaped cross-section fiber. As a result, at least a portion of the irregularly shaped cross-section fiber may include fibers derived from the irregularly shaped cross-section fiber (hereinafter sometimes referred to as "irregularly shaped cross-section fiber-derived fibers") which are formed when at least one of the convex portions constituting the irregularly shaped cross-section fiber is separated or peeled off. Since the said irregularly shaped cross-section fiber-derived fibers are formed when a part of the irregularly shaped cross-section fiber (i.e., the convex portion 2) is separated or peeled off from the main irregularly shaped cross-section fiber, they become extremely fine fibers with a smaller fiber cross-sectional area than the irregularly shaped cross-section fiber. Accordingly, in the nonwoven fabric of this embodiment, at least a portion of the irregularly shaped cross-section fibers contained in the nonwoven fabric may include peeled fibers formed by the division or peeling of at least one of the multiple protrusions contained in the irregularly shaped cross-section fibers, and at least a portion of the fibers derived from the irregularly shaped cross-section fibers may exist as ultrafine fibrous fibers.

[0021] The nonwoven fabric of this embodiment may include fibers derived from irregularly shaped cross-section fibers, in a portion of the irregularly shaped cross-section fibers, formed by the division or peeling of at least one protrusion of the irregularly shaped cross-section fiber. These fibers derived from irregularly shaped cross-section fibers, formed by the division or peeling of protrusions, may be ultrafine fibers with a smaller cross-sectional area than the irregularly shaped cross-section fibers.

[0022] Irregularly shaped cross-section fibers, whose fiber cross-sections are not distorted, have at least three protrusions that are highly effective at trapping dirt from the surface being wiped. In addition, the recesses formed between the protrusions make it easier to retain the trapped dirt. Furthermore, when the nonwoven fabric of this embodiment is used as a wiping sheet (a so-called wet wiping sheet) impregnated with a chemical solution, irregularly shaped cross-section fibers are highly effective at absorbing and retaining the chemical solution in the recesses, making it easier to obtain a wiping sheet with excellent sustained release properties of the chemical solution. Moreover, irregularly shaped cross-section fibers with distorted fiber cross-sections generate irregularly shaped fiber-derived fibers through protrusions that can be separated and peeled off from the original irregularly shaped cross-section fiber, and at least a portion of these irregularly shaped fiber-derived fibers may become ultrafine fibers. Whether or not the irregularly shaped fiber-derived fibers are completely separated and peeled off from the original irregularly shaped cross-section fiber, they retain the shape of the original protrusions, i.e., a flat, non-circular fiber cross-section shape, thus enhancing the effect of trapping dirt from the target surface.

[0023] In this embodiment, the maximum width Wt of the tip portion of the protrusion 2 in the fiber cross-section of the irregularly shaped cross-section fiber 1 contained in the nonwoven fabric is preferably 3.5 μm or more and 20 μm or less, more preferably 4.5 μm or more and 16 μm or less, and particularly preferably 5 μm or more and 14 μm or less. When the maximum width Wt of the tip portion of the protrusion 2 is within the above range, it is easier to obtain the effect of retaining dirt trapped in the recesses 3 formed between the protrusions. Furthermore, when the nonwoven fabric of this embodiment is used as a wiping sheet (so-called wet wiping sheet) impregnated with a chemical solution, it is easier to temporarily retain the chemical solution in the recesses. If the irregularly shaped cross-section fiber is hydrophilic, the chemical solution penetrates deeper into the recesses and is retained for a longer period of time, making it easier to obtain a wiping sheet with excellent performance in gradually releasing the chemical solution, i.e., sustained release of the chemical solution. If the irregularly shaped cross-section fiber is hydrophobic, the retained chemical solution does not penetrate deeper into the recesses and is easily replaced with air by external force, and a pumping effect tends to be easily exhibited.

[0024] In this embodiment, the width Wb of the root portion of the protrusion 2 in the fiber cross-section of the irregularly shaped cross-section fiber 1 contained in the nonwoven fabric is preferably 2 μm to 12 μm, more preferably 3.0 μm to 10 μm, and particularly preferably 3.5 μm to 8 μm. When the width Wb of the root portion of the protrusion 2 is within the above range, the protrusion 2 is more likely to peel, fibrillate, or separate from near its root due to various forces applied to the fiber during the nonwoven fabric manufacturing process, thereby making it easier to generate fibers derived from irregularly shaped cross-section fibers, especially ultrafine fibrous fibers derived from irregularly shaped cross-section fibers, and thus the resulting nonwoven fabric is more likely to have improved dirt-removing properties. Furthermore, the protrusions contained in the fiber cross-section of the irregularly shaped cross-section fiber 1 contained in the nonwoven fabric of this embodiment have a portion that is constricted toward the center of the fiber, and the width Wb of the root portion of the protrusion is smaller than the maximum width Wt of the protrusion. When the width Wb at the base of the protrusion becomes smaller than the maximum width Wt of the protrusion, the protrusion becomes more prone to peeling, fibrillation, or separation from its base, making it easier to generate extremely fine, irregularly shaped cross-sectional fibers.

[0025] In the nonwoven fabric of this embodiment, the maximum width (Wt) at the tip of the convex portion 2 in the fiber cross-section of the irregularly shaped cross-section fiber 1 is indicated by Wt in Figure 1. Specifically, it refers to the maximum length of the perpendicular lines drawn from the line connecting the center of the fiber to the tip of the convex portion 2 toward the outer shape of the convex portion. The width (Wb) at the base of the convex portion is indicated by Wb in Figure 1, and specifically refers to the length connecting the two ends of the base portions of adjacent convex portions. It is preferable that the ratio (Wt / Wb) of the maximum width Wt at the tip of the convex portion to the width Wb at the base portion is greater than 1 and 3.5 or less. When the ratio (Wt / Wb) of the maximum width Wt at the tip of the convex portion to the width Wb at the base portion satisfies the above range, the convex portion 2 is not only easily peeled, fibrillated, or separated from near its base, but also becomes an irregularly shaped cross-section fiber that is easy to manufacture. The ratio (Wt / Wb) of the maximum width Wt at the tip of the protrusion to the width Wb at the base is more preferably 1.2 to 3, particularly preferably 1.4 to 2.5, and most preferably 1.4 to 2. The maximum width Wt at the tip of the protrusion and the width Wb at the base can be determined by magnifying the cross-section of the manufactured nonwoven fabric with a scanning electron microscope or the like and averaging the values ​​of 15 arbitrary irregularly shaped cross-section fibers.

[0026] In this embodiment, the length Lt of the protrusions 2 contained in the fiber cross-section of the irregularly shaped cross-section fiber 1 is preferably 4 μm or more and 25 μm or less, more preferably 6.5 μm or more and 20 μm or less, and particularly preferably 8.0 μm or more and 16 μm or less. If the length Lt of the protrusions is less than 4 μm, the protrusions 2 become difficult to deform from the base. If the length Lt of the protrusions exceeds 25 μm, the area of ​​the protrusions becomes too large, and the fineness of the irregularly shaped cross-section fiber itself becomes too large, which may cause a decrease in the dirt-wiping performance of the nonwoven fabric containing it. When the length Lt of the protrusions is 4 μm or more and 25 μm or less, the protrusions 2 become easier to deform from the base, and the wiping performance is also better, so this is preferable. The length Lt of the protrusions can be determined by magnifying the cross-section of the manufactured nonwoven fabric with a scanning electron microscope or the like and averaging the values ​​of 15 arbitrary irregularly shaped cross-section fibers.

[0027] In the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment, it is preferable that the ratio (Lt / Wb) of the length Lt of the protrusion 2 to the width Wb of the root portion is 1 or more and 3.5 or less. When the ratio (Lt / Wb) of the length Lt of the protrusion to the width Wb of the root portion satisfies the above range, not only is it easier for the protrusion to peel, fibrillate, or separate from near its root, but the manufacturing of the fibers is also facilitated. It is more preferable that the ratio (Lt / Wb) of the length Lt of the protrusion to the width Wb of the root portion is 1.2 or more and 3 or less, particularly preferable that it is 1.4 or more and 2.7 or less, and most preferable that it is 1.5 or more and 2.5 or less.

[0028] The irregularly shaped cross-section fibers included in the nonwoven fabric of this embodiment may be fibers made of multiple resin components, such as composite fibers made of two types of resin components, as long as they can maintain their irregular cross-sectional shape, or they may be single fibers made of a single resin component. If the irregularly shaped cross-section fibers are single fibers made of a single resin component, the melt viscosity of the thermoplastic resin used as a raw material can be easily adjusted when manufacturing the fibers, making it easier to manufacture irregularly shaped cross-section fibers that satisfy a predetermined fiber cross-sectional shape.

[0029] The thermoplastic resin contained in the resin component, preferably a single resin component, is not particularly limited and may be arbitrarily selected from thermoplastic resins commonly used in the manufacture of fibers. Specifically, one or more resins may be selected and used from the group consisting of polyolefin resins such as polyethylene, polypropylene, polybutene-1, polymethylpentene, ethylene-propylene copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-methyl acrylate copolymer; aromatic polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; aliphatic polyester resins such as polylactic acid, polyethylene succinate, and polybutylene succinate; polyamide resins such as nylon 6 and nylon 66; polycarbonate resins; polyoxymethylene (polyacetal) resins; polyketone resins; polystyrene resins; vinylon resins; and acrylic resins. The raw materials for these thermoplastic resins are not particularly limited. They may be petroleum-derived thermoplastic resins, biomass-derived thermoplastic resins in which at least a portion of the raw materials are plant-derived, or recycled thermoplastic resins made by crushing, melting, and re-pelletizing a thermoplastic resin product that has been used once. The single resin component constituting the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment is preferably a resin component containing 50% by mass or more of polypropylene resin, more preferably a resin component containing 75% by mass or more of polypropylene resin, and particularly preferably a resin component containing 80% by mass or more of polypropylene resin. Polypropylene is a general-purpose resin that is readily available and has a wide range of resin properties, making it easy to manufacture fibers designed for various applications.

[0030] The polypropylene resin is not particularly limited and can be used as long as it is a polypropylene resin capable of melt spinning. However, it is preferable that the melt mass flow rate of the polypropylene resin conforming to JIS K 7210 (measured at a temperature of 230°C and a load of 2.16 kgf (21.18 N) or less, also simply referred to as "MFR230") is in the range of 5 g / 10 min to 50 g / 10 min, more preferably in the range of 10 g / 10 min to 45 g / 10 min, and particularly preferably in the range of 20 g / 10 min to 35 g / 10 min. When the MFR230 is within the above range, not only is yarn breakage less likely to occur during spinning, but the shear stress of the molten polypropylene resin becomes appropriately large, making it easier to maintain the fiber cross-sectional shape immediately after melt spinning, and making it easier to obtain irregularly shaped cross-sectional fibers having a predetermined cross-sectional shape.

[0031] The fineness of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment is not particularly limited, but is preferably 0.5 dtex or more and 10 dtex or less, more preferably 0.8 dtex or more and 5.6 dtex or less, and particularly preferably 1.0 dtex or more and 3.5 dtex or less. If the fineness of the irregularly shaped cross-section fibers exceeds 10 dtex, when the nonwoven fabric containing the irregularly shaped cross-section fibers is used as a wiping sheet, it may scratch the surface of the object or the feel of the wiping sheet may be reduced. If the fineness of the irregularly shaped cross-section fibers is less than 0.5 dtex, the carding ability of the irregularly shaped cross-section fibers decreases, making it difficult to produce the nonwoven fabric containing the irregularly shaped cross-section fibers. When the fineness of the irregularly shaped cross-section fibers is 0.5 dtex or more and 10 dtex or less, a softer texture is more easily produced, a more comfortable feel is obtained, and productivity is further improved. The irregularly shaped cross-section fibers may have a larger fiber cross-sectional area than any of fibers A1 to A3 or fibers 1 to 3, and / or a larger fiber cross-sectional area than the Smax of fiber A. Such irregularly shaped cross-section fibers, as thick fiber diameters, play a structural role in the fiber layer X and also enable the formation of interfiber voids of various sizes within the nonwoven fabric.

[0032] The fiber length of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment is not particularly limited, but is preferably 1 mm to 100 mm, more preferably 3 mm to 70 mm, and particularly preferably 5 mm to 65 mm. When the fiber length of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment satisfies the above range, the fibers become easier to intertwine with each other, and the nonwoven fabric of this embodiment has superior productivity.

[0033] The tensile strength (Ti) of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment is preferably greater than the tensile strength (Td) of the segmented composite fibers described later. It is more preferable that Ti ≥ 1.1 × Td. When the tensile strength of the irregularly shaped cross-section fibers and the tensile strength of the segmented composite fibers contained in the nonwoven fabric of this embodiment satisfy the above range, the "framework" role of the irregularly shaped cross-section fibers in the nonwoven fabric is more effectively exerted, various sizes of interfiber voids are formed, and the effect of trapping dirt into the interior of the nonwoven fabric is further enhanced.

[0034] The tensile strength (Ti) of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment is preferably 2.5 cN / dtex or higher, and more preferably 3.0 cN / dtex or higher. There is no particular upper limit to the tensile strength, but for example, it is preferably 7.0 cN / dtex or lower, and more preferably 6.5 cN / dtex or lower. When the tensile strength of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment satisfies the above range, the "framework" role of the irregularly shaped cross-section fibers in the nonwoven fabric is more effectively exerted, making it easier to form interfiber voids of various sizes, or imparting appropriate strength to the nonwoven fabric.

[0035] The irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment may contain a hydrophilic agent to enhance their hydrophilicity. The method for incorporating a hydrophilic agent into the resin component constituting the irregularly shaped cross-section fibers to enhance their hydrophilicity is not particularly limited. Specifically, the resin component can be made to contain a hydrophilic agent by methods such as mixing inorganic particles with the resin component, mixing a hydrophilic agent with the resin component, or mixing a modified polyolefin having polar groups with the resin component.

[0036] The hydrophilizing agent that can be added to the resin component is not particularly limited, as long as it is a compound having a hydrophilic group such as a hydroxyl group, a carbonyl group, a carboxyl group (also called a carboxyl group), or a sulfone group. Examples include fatty acid glycerides (polyglycerin fatty acid esters with a degree of polymerization of glycerin of 1 to 10, such as monoglycerin fatty acid esters, diglycerin fatty acid esters, triglycerin fatty acid esters, and tetraglycerin fatty acid esters), alkylene oxide adducts of polyglycerin with a degree of polymerization of glycerin of 1 to 10, and POE alkyl (C8-C) containing alkyl groups with 8 to 18 carbon atoms. 18 ) Phosphates, alkyl (C8~C) containing alkyl groups with 8 to 18 carbon atoms 18 ) Phosphates, alkyl (C8~C) containing alkyl groups with 8 to 18 carbon atoms 18 Examples include phosphate ester salts, alkoxylated alkylphenols, polyoxyalkylene fatty acid esters, and fatty acid diethanolamides. Modified polyolefins having polar groups that can be added to the resin component include polypropylene resin and polyethylene resin obtained by graft polymerization of maleic anhydride. The inorganic particles, hydrophilizing agents, and modified polyolefins having polar groups can be mixed in a range that does not significantly impede spinnability or fiber properties, and it is preferable to add them in a proportion of 0.1% by mass or more and 15% by mass or less when the total mass of the resin component (i.e., the total mass of the fibers) is 100% by mass, more preferably in a proportion of 0.5% by mass or more and 10% by mass or less, and particularly preferably in a proportion of 0.8% by mass or more and 8% by mass or less.

[0037] One method for increasing the hydrophilicity of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment is to attach a hydrophilizing agent to the surface of the irregularly shaped cross-section fibers. In this case, the hydrophilizing agent may be a durable hydrophilizing agent. The durable hydrophilizing agent has the property of remaining on the fiber surface and maintaining the hydrophilicity of the fibers even after entanglement treatment with high-pressure fluid flow (especially water flow) when manufacturing the nonwoven fabric of this embodiment using the manufacturing method described later. Specifically, the durable hydrophilizing agent is such that the initial sedimentation velocity of the fibers is 60 seconds or less, and the post-wash sedimentation velocity after washing with 40°C hot water for 2 minutes three times is also 60 seconds or less. The post-wash sedimentation velocity may be lower than the initial sedimentation velocity as long as it is 60 seconds or less.

[0038] As a method to enhance the hydrophilicity of the irregularly shaped cross-section fibers contained in the nonwoven fabric of this embodiment, the hydrophilicity of the irregularly shaped cross-section fibers may be improved by hydrophilic treatment. Examples of hydrophilic treatments include fluorine gas treatment, plasma discharge treatment, and corona discharge treatment. When performing corona discharge treatment, although not particularly limited, the discharge amount per cycle in corona discharge treatment is 50 W·min / m 2 Preferably, the total discharge rate is 100 W·min / m 2 More than 5000W min / m 2 The following is preferable. A more preferable total discharge rate is 250 W·min / m 2 More than 5000W min / m 2 The following applies. Furthermore, while the plasma treatment is not particularly limited, it is preferably atmospheric pressure plasma treatment, and it is advisable to perform the treatment under conditions of a voltage of 50kV to 250kV and a frequency of 500pps to 3000pps. Atmospheric pressure plasma treatment is advantageous because it allows for treatment at a low voltage, resulting in less fiber degradation. Furthermore, while the fluorine gas treatment is not particularly limited, it can be performed using, for example, a mixed gas containing fluorine gas and oxygen gas, or a mixed gas containing fluorine gas and sulfur dioxide gas.

[0039] (Fiber A) The fiber layer X1 constituting the nonwoven fabric of this embodiment includes fibers A made of thermoplastic resin in addition to irregularly shaped cross-section fibers. The fiber layer X1 includes multiple fibers A with different cross-sectional shapes and areas, which may be classified into fibers A1 having a cross-sectional area less than 0.25 times the maximum cross-sectional area Smax of fiber A, fibers A2 having a cross-sectional area of ​​0.25 times or more and 0.5 times or less, and fibers A3 having a cross-sectional area greater than 0.5 times and 1 time or less. These fibers A1 to A3 can each be prepared separately, or they can be present in the fiber layer X1 by partially dividing a split-type composite fiber. When using a split-type composite fiber, by adjusting its splitting properties (ease of division), these fibers can be easily obtained from a single type of fiber without having to prepare multiple fibers with different cross-sectional areas and shapes. The split-type composite fiber that forms fibers A1 to A3 will be described below.

[0040] (Split-type composite fiber) A split-type composite fiber is a composite fiber consisting of two or more components, and is a fiber that can form multiple fibers of lower fineness from a single fiber through splitting. Fibers A1 to A3 may exist in the nonwoven fabric as fibers derived from the split-type composite fiber. "Fibers derived from the split-type composite fiber" refers to a single fiber consisting of only one section before splitting, and a fiber consisting of two or more sections formed by the splitting of the split-type composite fiber, as well as a fiber in which a part of a single split-type composite fiber is split, but the rest of the fiber is not split at all. The nonwoven fabric of this embodiment may contain split-type composite fibers that are not split at all, but it is preferable to include fibers derived from split-type composite fibers in order to improve the wiping performance of the nonwoven fabric, soften the contact with the surface of the object, and reduce the amount of liquid residue.

[0041] Specifically, the segmented composite fiber has a fiber cross-sectional structure in which at least one of the constituent components is divided into two or more parts in the fiber cross-section, at least a portion of the constituent component is exposed on the fiber surface, and the exposed portion is continuously formed in the longitudinal direction of the fiber.

[0042] For example, a split-type composite fiber may be composed of a combination of a first polyolefin resin or polyester resin (high melting point component) and a second polyolefin resin or low melting point polyester resin (second component) different from the first polyolefin resin or polyester resin (first component). Specifically, the first component may be polypropylene, polymethylpentene, polyethylene terephthalate, polytrimethylene terephthalate, polylactic acid, etc. The second component may be polypropylene high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-propylene copolymer, polybutene-1, polybutylene succinate, etc. The combination of the first and second components may be polyethylene terephthalate / high-density polyethylene or polyethylene terephthalate / polypropylene. These combinations do not result in high compatibility between the resins, and while splitting provides fibers with a small cross-sectional area, the resins themselves are hydrophobic, making it easy to obtain split-type composite fibers that repel water easily when split by the water flow entanglement treatment described later, thus preventing excessive splitting. Therefore, it facilitates the formation of fibers A1 to A3 having specific fiber cross-sectional areas in the fiber layer X.

[0043] Alternatively, the combination of the first and second components may be a combination of a polyamide resin and a polyester resin, or a combination of a polyamide resin and a polyolefin resin. An example of a polyamide resin is as explained in relation to the thermoplastic resin that constitutes the irregularly shaped cross-section fibers.

[0044] The fineness of the split composite fiber is not particularly limited, as long as it provides an ultrafine fiber with a fineness of 0.6 dtex or less, preferably 0.5 dtex or less, when divided into its components (i.e., when each section becomes a single fiber).

[0045] To generate such ultrafine fibers, the fineness of the divided composite fiber is preferably 1 dtex or more and 6 dtex or less, more preferably 1.3 dtex or more and 4 dtex or less, and particularly preferably 1.5 dtex or more and 3 dtex or less. Furthermore, the number of divisions into each component in the divided composite fiber (i.e., the number of sections in the composite fiber) is preferably 4 or more and 32 or less, more preferably 4 or more and 20 or less, and particularly preferably 6 or more and 16 or less. If the number of divisions is small, it is necessary to reduce the fineness before division in order to form ultrafine fibers with a fineness of 0.6 dtex or less. The lower limit of the fineness of the ultrafine fiber is not particularly limited, but it is preferably 0.05 dtex or more.

[0046] The shape of the sections is not particularly limited. For example, a segmented composite fiber may have wedge-shaped sections arranged in a chrysanthemum-like pattern in the fiber cross-section. A segmented composite fiber with sections arranged in this way provides fibers with a wedge-shaped cross-sectional shape after segmentation, and such fibers have excellent dirt-scraping properties. Furthermore, such segmented composite fibers, when combined with the aforementioned specific irregularly shaped cross-sectional fibers, also provide voids of various shapes and dimensions. As a result, fiber pockets suitable for holding solid matter derived from dirt, liquids impregnated into the nonwoven fabric, and wiped-off liquids are more easily formed, which is thought to further improve wiping performance, liquid retention, and sustained release. Alternatively, a segmented composite fiber may have multiple petal-shaped or fan-shaped sections made of one resin component joined to sections of other resin components in its cross-section, thereby providing a petal-shaped or fan-shaped fiber through segmentation. Alternatively, a segmented composite fiber may have a trefoil shape (also called a Y-shape) with three protrusions in its cross-section, with divisible sections at the tips of these protrusions. A segmented composite fiber may be a so-called solid segmented composite fiber that does not have a continuous cavity in the longitudinal direction when its cross-section is observed, or it may be a so-called hollow segmented composite fiber that has one or more continuous cavities in the longitudinal direction.

[0047] The volume ratio of the first component to the second component constituting the split composite fiber described above is not particularly limited, but is preferably 2:8 to 8:2 (volume of the first component:volume of the second component), more preferably 3:7 to 7:3 (volume of the first component:volume of the second component), and particularly preferably 35:65 to 65:35 (volume of the first component:volume of the second component).

[0048] The fiber length of the segmented composite fiber is not particularly limited, but is preferably 20 mm to 100 mm, more preferably 25 mm to 70 mm, and especially preferably 30 mm to 65 mm. When the fiber length of the segmented composite fiber contained in the nonwoven fabric of this embodiment satisfies the above range, the fibers become easier to intertwine with each other, and the nonwoven fabric of this embodiment becomes more productive.

[0049] The tensile strength (Ts) of the split composite fiber is preferably 1.5 cN / dtex or higher, and more preferably 2.0 cN / dtex or higher. There is no particular upper limit to the tensile strength, but for example, it is preferably 4.0 cN / dtex or lower, and more preferably 3.5 cN / dtex or lower. When the tensile strength of the split composite fiber satisfies the above range, it becomes easier to split the fibers and easily intertwines with the "framework" formed by the irregularly shaped cross-section fibers, and also provides voids of various shapes and dimensions.

[0050] As described later, it is preferable that the divided composite fiber is divided such that fibers A1 to A3, each having a specific cross-sectional area, exist within the fiber layer X of the nonwoven fabric, or that it is divided within a predetermined division ratio. Such a divided composite fiber is one in which no division occurs between sections, and can be obtained by selecting the combination of resins and the shape of the sections. Alternatively, the degree of division of the divided composite fiber is also affected by the manufacturing conditions of the nonwoven fabric, so these factors should also be taken into consideration when manufacturing or selecting the divided composite fiber to be divided as desired.

[0051] (Other fibers) The fiber layer X1 may contain fibers with irregular cross-sections and / or fibers derived from fibers with irregular cross-sections, as well as fibers other than fiber A (e.g., split-type composite fibers and / or fibers derived from split-type composite fibers) (also referred to as "other fibers"). Other fibers may be, for example, synthetic fibers made of thermoplastic resin that do not have an irregular cross-section and are not split-type composite fibers. The thermoplastic resin constituting the synthetic fibers is not particularly limited and may be manufactured using one or more thermoplastic resins arbitrarily selected from, for example, those exemplified as thermoplastic resins constituting fibers with irregular cross-sections.

[0052] The synthetic fiber may be a single fiber composed of one or more thermoplastic resins selected from the above, or it may be a composite fiber composed of two or more components (also called "sections") that is not a segmented composite fiber. In the composite fiber, each component may consist of one thermoplastic resin, or it may be a mixture of two or more thermoplastic resins. The composite fiber may be, for example, a core-sheath composite fiber, a sea-island composite fiber, or a side-by-side composite fiber. The core-sheath composite fiber may be an eccentric core-sheath composite fiber in which the centers of the core component and the centers of the sheath component do not coincide in the fiber cross-section, or a concentric core-sheath composite fiber in which the centers of the core component and the centers of the sheath component coincide in the fiber cross-section.

[0053] Alternatively, other fibers contained in the fiber layer X1 may be cellulose fibers. Examples of cellulose fibers include: (1) Natural fibers derived from plants such as cotton, hemp, linen, ramie, jute, banana, bamboo, kenaf, ginger lily, hemp, and kapok; (2) Rayon and polynosic obtained by the viscose method, cupro obtained by the copper ammonia method, and lyocell (e.g., Tencel®), which is a solvent-spun cellulose fiber, as well as other regenerated fibers; (3) Cellulose fibers obtained by melt spinning; and (4) Semi-synthetic fibers such as acetate fibers These are some examples.

[0054] Alternatively, the other fibers contained in the fiber layer X1 and the fiber layer Y described below may be protein fibers such as silk and wool.

[0055] The fiber length of the other fibers is not particularly limited. For example, it is preferably 20 mm or more and 100 mm or less, more preferably 25 mm or more and 70 mm or less, and particularly preferably 30 mm or more and 65 mm or less. When the fiber length of the other fibers contained in the non-woven fabric of the present embodiment satisfies the above range, it becomes easier to entangle the fibers with each other, and the non-woven fabric of the present embodiment is more excellent in productivity.

[0056] (Fiber layer X1) Next, the fiber layer X1 will be described. The fiber layer X1 contains 10% by mass or more and 90% by mass or less of the profiled fibers and / or the fibers derived from the profiled fibers, and 10% by mass or more and 90% by mass or less of the fiber A made of a thermoplastic resin whose fiber cross-section is not circular. The fiber A contains a plurality of fibers having different fiber cross-sectional shapes and areas. When the total number of fibers of the fiber A in the fiber layer X1 is 100%, the fiber layer X1 may contain the following fibers A1 to A3 in the following ratios as the fiber A. (i) Fiber A1 having a fiber cross-sectional area less than 0.25 times the maximum fiber cross-sectional area Smax of the fiber A: 20% or more and 85% or less, particularly 25% or more and 80% or less (ii) Fiber A2 having a fiber cross-sectional area of 0.25 times or more and 0.5 times or less the maximum fiber cross-sectional area Smax of the fiber A: 5% or more and 60% or less, particularly 7% or more and 55% or less (iii) Fiber A3 having a fiber cross-sectional area exceeding 0.5 times and not exceeding 1 times the maximum fiber cross-sectional area Smax of the fiber A: 10% or more and 70% or less, particularly 15% or more and 65% or less.

[0057] The maximum fiber cross-sectional area Smax of the fiber A is 2 more than 150 μm 2 and preferably not more than 1300 μm 2 more preferably not less than 180 μm 2 and not more than 1000 μm 2 even more preferably not less than 200 μm 2The following are particularly preferable.

[0058] The cross-sectional area of ​​fibers A1 to A3, the fiber cross-sectional area Smax, and the proportion of fibers A1 to A3 are measured by the following method. (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) From the captured image, count the number of fibers A and measure the fiber cross-sectional area using the image analysis software "Micro Measure".

[0059] If fiber A is a split-type composite fiber or a fiber derived from a split-type composite fiber, then fibers A1 to A3 are fibers formed by the splitting of the split-type composite fiber. Fiber A1 roughly corresponds to a fiber consisting of one section of the split-type composite fiber, fiber A2 roughly corresponds to a fiber formed by the bonding of multiple sections of the split-type composite fiber, and fiber A3 roughly corresponds to a fiber remaining after the split-type composite fiber has not split at all or after one or two sections have split. The fiber cross-sectional area of ​​the fibers formed by the splitting of the split-type composite fiber varies depending on the fiber diameter and number of sections of the split-type composite fiber before splitting, so the above is merely a guideline. As long as fibers with the above cross-sectional area are included in the above proportions, the number of sections constituting fibers A1 to A3 is not limited.

[0060] Alternatively, the fiber layer X1 may be defined as containing 10% to 90% by mass of fibers derived from irregularly shaped cross-section fibers and 10% to 90% by mass of fibers derived from segmented composite fibers. In that case, the fiber layer X1 may satisfy at least one of the following groups (i) to (iii) when the total number of fibers derived from segmented composite fibers is taken as 100%. (i) The proportion of fiber 1 (fibers having a cross-sectional area less than 0.25 times the cross-sectional area of ​​undivided divided composite fibers) is 20% or more and 85% or less, especially 25% or more and 80% or less. (ii) The proportion of fiber 2 (fibers having a cross-sectional area of ​​0.25 times or more and 0.5 times or less than the cross-sectional area of ​​the undivided divided composite fiber) is 5% or more and 60% or less, especially 7% or more and 55% or less. (iii) The proportion of fiber 3 (fibers having a cross-sectional area greater than 0.5 times the cross-sectional area of ​​undivided divided composite fibers) is 10% to 70%, especially 15% to 65%.

[0061] If the fiber layer X1 satisfies at least one selected from the group consisting of (i) to (iii), then the fiber layer X1 includes not only ultrafine fibers consisting of only one section, but also fibers with various cross-sectional areas, such as fibers formed by the bonding of multiple sections. Therefore, fibers derived from such segmented composite fibers, like fibers A1 to A3, can be combined with fibers derived from irregularly shaped cross-section fibers and / or irregularly shaped surface fibers to give a nonwoven fabric in which the characteristics of each fiber are well exhibited.

[0062] The proportion of fibers 1-3 in the nonwoven fiber layer X1 can be determined by the following method. (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) The number of fibers derived from the segmented composite fiber is counted from the captured image, and the cross-sectional area of ​​the fiber is measured using the image analysis software "Micro Measure".

[0063] When the surface of the fiber layer X1 containing the aforementioned specific fibers in the aforementioned specific proportion is used as a wiping surface for wiping and / or polishing, it becomes possible to wipe away dirt from the surface of an object with light force and to uniformly apply a finishing agent to the surface of the object. More specifically, the irregularly shaped cross-section fibers play a skeletal role in the fiber layer X1, increasing the bulk of the fiber layer X1, enabling wiping / polishing with light force, and improving dirt removal due to the shape of their cross-sections. Fibers A1 to A3, or fibers 1 to 3 derived from the segmented composite fibers, and fibers derived from the irregularly shaped cross-section fibers play a role in wiping away fine dirt due to their small fineness or fiber diameter, and the small interfiber voids formed by the ultrafine fibers draw up liquid from the surface of the object by capillary action, reducing the amount of liquid remaining on the surface of the object.

[0064] The fiber layer X1 may not contain fibers derived from the irregularly shaped cross-section fibers, depending on the shape of the fiber cross-section and the conditions of the entanglement treatment. Even in this case, since there are ultrafine or fine fiber originating from fibers A1-A3 or fibers 1-3, the dirt-wiping performance of the fiber layer X1 surface will not be significantly reduced. On the other hand, when the fiber layer X1 is manufactured using split-type composite fibers, at least a portion of the split-type composite fibers must split to form fibers derived from the split-type composite fibers. This is because if there are no fibers derived from the split-type composite fibers, the dirt-wiping and liquid absorption will be insufficient. Therefore, when manufacturing the nonwoven fabric of this embodiment using split-type composite fibers, the entanglement treatment conditions are set so that fibers 1-3 (or fibers A1-A3) derived from the split-type composite fibers are formed during manufacturing.

[0065] In the fiber layer X1, it is preferable that striated voids are formed between the ultrafine fibers of the ultrafine fiber group, which is formed by bundling together ultrafine fibers derived from segmented composite fibers. Since such striated voids have a structure similar to the striated recesses formed between the convex portions of irregularly shaped cross-section fibers, it is easier to obtain properties that are exhibited due to both the shape of the ultrafine fiber group and the shape of the irregularly shaped cross-section fibers. Furthermore, the ultrafine fibers derived from the split-type composite fibers are mainly based on fibers A1 and A2, or fibers 1 and 2. By adjusting the degree of splitting, the proportion of ultrafine fibers with different cross-sectional areas (i.e., thickness) and cross-sectional shapes can be adjusted, thereby adjusting the size of the voids present in fiber X1.

[0066] The fiber cross-sectional shape of ultrafine fibers derived from segmented composite fibers is preferably a tapered shape in which the length near one end in the width direction (direction perpendicular to the line segment connecting one end and the other end) of the fiber cross-sectional shape, such as leaf-shaped, teardrop-shaped, fan-shaped, trapezoidal, wedge-shaped, or conical, is shorter than the length in the width direction including the other end. In a tapered shape, the length in the width direction of one end is smaller than the length in the width direction of the other end, and the ratio (length in the width direction of the other end / length in the width direction of one end) is preferably 1.1 times or more, and more preferably 1.2 times or more. Alternatively, the tapered shape may be such that the vicinity of one end is pointed and the length in the width direction at that end is substantially zero. On the other hand, the convex portion of the irregularly shaped cross-section fiber described above preferably has a tapered shape at the base, as indicated by the ratio (Wt / Wb) of the maximum width Wt at the tip to the width Wb at the base. In particular, a multi-lobed cross-section shape is preferred.

[0067] The cross-sectional shape of the convex portion of the multi-lobed, irregularly shaped cross-section fibers is similar to the cross-sectional shape of fibers A1 and A2, or fibers 1 and 2, of the ultrafine fiber group, when the shape of the ultrafine fibers described above is tapered. Furthermore, the fiber side shape of the multi-lobed, irregularly shaped cross-section fibers is similar to that of the ultrafine fiber group. These similarities are presumed to give the nonwoven fabric a unique function (e.g., wipeability, tactile feel, etc.) derived from the shapes of both the ultrafine fiber group (especially fibers A1 and A2, or fibers 1 and 2) and the irregularly shaped cross-section fibers.

[0068] Furthermore, the ratio (Ld / Lt) of the length of the long side in the fiber cross-section of the ultrafine fibers derived from the split-type composite fibers (particularly fibers A1 and A2, or fiber 1 and fiber 2) to the length of the convex portion of the irregularly shaped cross-section fiber is preferably 0.6 or more and 1.6 or less. More preferably, it is 0.7 or more and 1.4 or less, and 0.8 or more and 1.3 or less. It is presumed that the approximation of the length of the long side in the fiber cross-section derived from the split-type composite fibers and the length of the convex portion of the irregularly shaped cross-section fiber gives the nonwoven fabric a unique function (e.g., wipeability, tactile feel, etc.) derived from both cross-sectional lengths.

[0069] The proportion of irregularly shaped cross-section fibers and / or fibers derived from said irregularly shaped cross-section fibers may be particularly 10% by mass or more and 90% by mass or less, more particularly 10% by mass or more and 60% by mass or less, and even more particularly 10% by mass or more and 40% by mass or less. The proportion of fibers A1 to A3, or split-type composite fibers and fibers derived from split-type composite fibers may be particularly 10% by mass or more and 90% by mass or less, more particularly 40% by mass or more and 90% by mass or less, and even more particularly 60% by mass or more and 90% by mass or less. If there is too little of either the irregularly shaped cross-section fibers and / or the fibers derived from the irregularly shaped cross-section fibers, or fibers A1 to A3 or the segmented composite fibers and the fibers derived from the segmented composite fibers, and too much of the other, the balance of the roles of each fiber will be disrupted. As a result, when the nonwoven fabric of this embodiment is used as a wiping cloth, the performance of wiping away dirt, wiping with light force, and removing liquid residue may be inferior.

[0070] If the fiber layer X1 contains other fibers, the proportion of other fibers may be 80% by mass or less, particularly 70% by mass or less, and more particularly 60% by mass or less. Alternatively, the fiber layer X1 may not contain other fibers and may consist only of irregularly shaped cross-section fibers and / or fibers derived from irregularly shaped cross-section fibers, and fibers A1 to A3 or split-type composite fibers and fibers 1 to 3 derived from split-type composite fibers. If the proportion of other fibers increases, the absolute amount of irregularly shaped cross-section fibers and / or fibers derived from irregularly shaped cross-section fibers, as well as fibers A1 to A3 or split-type composite fibers and fibers 1 to 3 derived from split-type composite fibers, decreases. As a result, the performance of these fibers may not be fully exhibited in the wiping cloth using the nonwoven fabric of this embodiment.

[0071] In the fiber layer X1, some of the fibers may be bonded to each other. The bonding may be by one or more of the fibers A1 to A3 (or fibers 1 to 3 derived from the split-type composite fiber), or by other fibers. Bonding can improve the strength of the nonwoven fabric. When fibers A1 and / or A2, or fibers 1 and / or 2 are bonded to each other, the bonding points are formed by relatively fine fibers, so the nonwoven fabric is less likely to become stiff, and the impact of bonding on the texture and feel can be minimized.

[0072] (Fiber layer Y) The nonwoven fabric of this embodiment may further include a fiber layer Y other than the fiber layer X1. The fiber layer Y may be laminated on only one side of the fiber layer X1, or the fiber layer Y, described later, may be located between the two fiber layers X1. In this case, the two fiber layers X1 may be different from each other or the same, as long as they contain specific fibers in specific proportions as described above. For example, the two fiber layers X1 may differ from each other in one or more respects, such as the cross-sectional shape of the irregularly shaped fiber, the type of thermoplastic resin constituting the irregularly shaped fiber, the proportion of the irregularly shaped fiber, the number of sections of the divided composite fiber, the combination of thermoplastic resins constituting the divided composite fiber, and the proportion of the divided composite fiber. By making the two fiber layers X1 different, it becomes possible to use both sides of the nonwoven fabric as wiping surfaces for different objects.

[0073] Fiber layer Y is a fiber layer with a different composition from fiber layer X1, and is constructed by selecting the constituent fibers and basis weight, etc., according to the application of the nonwoven fabric. For example, when the nonwoven fabric is used as the base material for a wiping cloth, fiber layer Y is provided for the purpose of adjusting the basis weight and thickness of the nonwoven fabric to take into account the workability and handling during wiping / cleaning, to function as a layer that holds liquid when the wiping cloth is impregnated with liquid, and / or to improve the overall strength of the nonwoven fabric.

[0074] The fiber layer Y contains 10% by mass or more of short fibers with a fiber length of 200 mm or less. Preferably, the fiber layer Y may contain 30% by mass or more of short fibers, more preferably 40% by mass or more, and even more preferably 50% by mass or more.

[0075] The fiber length of the short fibers may be, for example, 1 mm to 200 mm, particularly 3 mm to 100 mm, more particularly 5 mm to 80 mm, and even more particularly 10 mm to 65 mm, and can be appropriately selected depending on the application. The fiber layer Y may contain short fibers of different fiber lengths.

[0076] The fibers constituting the fiber layer Y are not particularly limited and can be arbitrarily selected from, for example, natural fibers such as pulp, hemp, silk, and wool (excluding cotton), regenerated fibers such as viscose rayon, cupro, and solvent-spun cellulose fibers (e.g., lentinglyocell® and Tencel®), and synthetic fibers.

[0077] The resins constituting the synthetic fibers can be arbitrarily selected from polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and its copolymers; polyolefin resins such as polypropylene, polyethylene (including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer; polyamide resins such as nylon 6, nylon 12, and nylon 66; acrylic resins; engineering plastics such as polycarbonate, polyacetal, polystyrene, and cyclic polyolefins; and elastomers thereof.

[0078] For example, when a fiber layer Y is provided for the purpose of liquid retention, the fiber layer Y may be a layer containing hydrophilic fibers. Hydrophilic fibers include, for example, cellulose fibers, protein fibers, and hydrophilic synthetic fibers. In this embodiment, cellulose fibers are preferably used as hydrophilic fibers from the viewpoint of easily maintaining hydrophilicity.

[0079] Examples of cellulose fibers are as previously described in relation to other fibers that can constitute the fiber layer X1. As an example of hydrophilic fibers, cellulose fibers may be used, such as regenerated fibers or semi-synthetic fibers. Since the variation in fineness and / or fiber diameter, as well as fiber length, of chemical fibers is smaller than that of natural fibers, it is easier to adjust the degree of entanglement of the nonwoven fabric. Furthermore, regenerated fibers such as rayon and solvent-spun cellulose fibers have a good balance between the softness and strength when wet, making it easier to obtain a soft texture and strength suitable for a nonwoven fabric, and are therefore preferred. Solvent-spun cellulose fibers are also preferred because they have relatively high single-fiber strength, resulting in better strength of the nonwoven fabric. Rayon has lower single-fiber strength compared to solvent-spun cellulose fibers, but is therefore preferred because it results in a softer nonwoven fabric and has high entanglement.

[0080] Protein-based fibers include natural fibers such as silk and wool.

[0081] Examples of hydrophilic synthetic fibers include synthetic fibers composed of hydrophilic thermoplastic resins, synthetic fibers containing a hydrophilizing agent in a hydrophobic thermoplastic resin, synthetic fibers coated with a hydrophilizing agent in a hydrophobic synthetic fiber, and synthetic fibers subjected to a hydrophilic treatment in a hydrophobic synthetic fiber. Examples of thermoplastic resins constituting synthetic fibers are as previously explained in relation to irregularly shaped cross-section fibers, and the types of hydrophilizing agents to be included in the thermoplastic resin, the methods for including the hydrophilizing agent in the thermoplastic resin, the hydrophilizing agents used when attaching the hydrophilizing agent to the fiber surface, and the methods of hydrophilic treatment are also as previously explained in relation to irregularly shaped cross-section fibers.

[0082] Hydrophilic fibers, which are obtained by applying a hydrophilic fiber treatment agent to the surface of synthetic fibers, are synthetic fibers that are hydrophobic in themselves, and whose sedimentation velocity, measured by the method described later, is, for example, 60 seconds or more when the hydrophilic fiber treatment agent is not applied. Furthermore, in synthetic fibers coated with a hydrophilic treatment agent, a hydrophobic thermoplastic resin is exposed at the fiber end face, making it difficult for liquid (especially water) to be absorbed from the fiber end face, and the fiber is less likely to swell due to liquid absorption. On the other hand, cellulose fibers exhibit hydrophilicity throughout and have the property of swelling when they absorb liquid, and as a result of swelling, the rigidity of the fiber tends to decrease. Therefore, compared to cellulose fibers, synthetic fibers coated with a hydrophilic fiber treatment agent are less prone to entanglement of fibers by high-pressure liquid flow (especially high-pressure water flow), and tend to make the nonwoven fabric bulkier.

[0083] The fineness of the hydrophilic fibers is not particularly limited, but in this embodiment, hydrophilic fibers with relatively small fineness are preferably used. Specifically, they may be 0.3 dtex or more and 7.8 dtex or less, more preferably 0.5 dtex or more and 5.6 dtex or less, particularly 0.6 dtex or more and 4.4 dtex or less, and more preferably 0.7 dtex or more and 3.3 dtex or less. If the fineness is too small, the entanglement of the fibers in the fiber layer Y becomes dense, reducing the interfiber gaps, which reduces the liquid retention capacity of the fiber layer Y, and also reduces the overall bulk of the nonwoven fabric, which can decrease its handling during wiping / cleaning. If the fineness is too large, the liquid retention capacity may decrease.

[0084] The fiber length of the hydrophilic fiber may be, for example, 20 mm or more and 100 mm or less, particularly 25 mm or more and 70 mm or less, and more particularly 30 mm or more and 60 mm or less. When the fiber length of the hydrophilic fibers is within the above range, the entanglement of the fibers tends to be favorable when manufacturing the nonwoven fabric by the method described later (especially the method in which the entanglement treatment includes water flow entanglement treatment). Furthermore, when the fiber length of the hydrophilic fibers is within the above range, the hydrophilic fibers are less likely to be exposed on the surface of the fiber layer X1, and when the nonwoven fabric of this embodiment is used as a wiping cloth, less liquid residue is likely to occur.

[0085] Alternatively, the fiber length of the hydrophilic fiber may be between 1 mm and 20 mm. Fibers of such length are used, for example, when forming a fiber layer in an airlaid or wet papermaking method.

[0086] In the fiber layer Y, hydrophilic fibers can be used alone or in combination. For example, the hydrophilic fibers may be one or more types of cellulose fibers, or one type of cellulose fiber and one type of hydrophilic synthetic fiber.

[0087] The degree of hydrophilicity of hydrophilic fibers can be evaluated using values ​​such as the sedimentation velocity of the fibers. The settling velocity (or settling time (seconds)) of the hydrophilic fibers used in this embodiment may be, for example, less than 60 seconds, particularly 50 seconds or less, more particularly 40 seconds or less, even more particularly 30 seconds or less, and even more particularly 20 seconds or less. The smaller the settling velocity (or settling time) of the hydrophilic fibers, the higher the entanglement of the hydrophilic fibers tends to be.

[0088] The sedimentation velocity of the fibers can be measured by the following method. 17g of fiber is collected to measure the settling velocity. The collected fiber is opened (using a parallel carding machine) to form a card web. 5g of the card web is weighed and packed into a copper wire (0.55mm thickness) cage (5cm diameter, 8cm height, cage body mass 3g). Next, prepare a constant-temperature water bath, fill it with tap water, and stir while adjusting the water temperature to 25°C. Once the water temperature reaches 25°C, stop stirring the water bath and begin measuring the sedimentation velocity. Gently drop the basket filled with fibers, prepared using the above procedure, from a height of 1 cm above the water surface, and start the stopwatch as soon as the basket hits the water. Gradually, the fibers will absorb water, and stop the stopwatch as soon as the 8 cm high basket is completely submerged. The time from when the basket hits the water surface until it is completely submerged is defined as the sedimentation velocity, and the average of the two measurements is taken as the sedimentation velocity of the fibers. When the material being measured is short fibers such as pulp, the fibers are opened by hand, and the basket containing the opened fibers is made of a fine mesh to prevent fiber leakage. The same test is then performed to determine the settling velocity.

[0089] Furthermore, natural fibers such as cotton and wool have a property of repelling water that comes into contact with their surface due to oil adhering to the fiber surface or the structure of the fiber surface, which can reduce the texture of the fabric when the fibers are integrated by water entanglement treatment as described later. For this reason, when natural fibers are used as hydrophilic fibers in this embodiment, oil removal and modification of the fiber surface may be carried out.

[0090] The fiber layer Y may contain, for example, 10% by mass or more, particularly 30% by mass or more, and more particularly 50% by mass or more, hydrophilic fibers. Alternatively, the fiber layer Y may be formed solely of hydrophilic fibers. When the fiber layer Y contains a large amount of hydrophilic fibers, when the nonwoven fabric is manufactured by the method described later (particularly the method in which the entanglement treatment includes a water flow entanglement treatment), the inter-fiber entanglement between the fiber layer X1 and the fiber layer Y becomes strong, which can improve the mechanical strength of the nonwoven fabric.

[0091] Even when the purpose of the fiber layer Y is to retain liquid, it may contain non-hydrophilic fibers, or may consist solely of non-hydrophilic fibers. Even if the fiber layer Y does not contain hydrophilic fibers, the voids formed between the fibers play a role in retaining liquid, and when the amount of liquid to be impregnated into the wiping cloth is small, such voids alone can sufficiently retain the liquid. For example, if the non-hydrophilic fibers are synthetic fibers, compared to cellulose fibers, the rigidity of the nonwoven fabric can be increased, giving the nonwoven fabric more body and improving its handling.

[0092] (Composition of nonwoven fabric) The nonwoven fabric of this embodiment has a single-layer structure composed only of fiber layers X1, a laminated structure in which different types of fiber layers X1 are laminated, or a laminated structure including fiber layer X1 and the fiber layer Y, and the fibers are intertwined and integrated. Preferably, the nonwoven fabric of this embodiment is integrated only by the intertwining of fibers and the fibers are not bonded to each other. Bonded areas where fibers are bonded to each other are generally hard, and for example, when the nonwoven fabric is used as a wiping cloth, it may scratch the surface of the object or reduce the tactile feel. Therefore, if bonding the fibers to each other is necessary, for example, to improve the mechanical strength of the nonwoven fabric, it is preferable to use fibers A1 to A3, or fibers with a relatively small fiber diameter or fineness formed by the division of a divided composite fiber, as the bonding component to join the fibers together. By using such fibers as the bonding component, the bonded area is not small, and the degree to which the nonwoven fabric hardens due to bonding can be reduced.

[0093] The basis weights of fiber layer X1 and fiber layer Y are not particularly limited and can be appropriately selected depending on the application of the nonwoven fabric. For example, when the nonwoven fabric is composed only of fiber layer X1, the basis weight of fiber layer X1 (or the overall basis weight of the laminated layer if multiple fiber layers X1 are laminated) is, for example, 30 g / m². 2 More than 200g / m 2 The following may be used, in particular 40 g / m² 2 More than 150g / m 2 The following is more specifically 50g / m 2 More than 100g / m 2 The following is acceptable:

[0094] In this embodiment, when the nonwoven fabric has a laminated structure in which a fiber layer Y is located between two fiber layers X1, the basis weight of the fiber layers X1 located on both sides of fiber layer Y is, for example, 10 g / m². 2 More than 90g / m 2 The following may be used, in particular 15 g / m² 2 More than 85g / m 2 The following is more specifically 20g / m 2 More than 80g / m 2The following may apply: When the nonwoven fabric of this embodiment is used as a wiping cloth, the fiber layer X1 becomes the wiping surface and has the ability to provide wiping performance and finishing agent. Furthermore, when the wiping cloth is impregnated with liquid and wiping and polishing are performed, the ultrafine fibers derived from the fibers A1 or segmented composite fibers, which have a small cross-sectional area, exhibit capillary action to absorb excess liquid and deliver it to the fiber layer X1.

[0095] The basis weight of the fiber layer Y is, for example, 5 g / m². 2 More than 50g / m 2 The following may be used, in particular 8 g / m² 2 More than 40g / m 2 The following is more specifically 8g / m 2 More than 30g / m 2 The following may apply: The fiber layer Y plays a role in adjusting the basis weight and thickness of the nonwoven fabric in this embodiment, taking into consideration the workability and handling during wiping / cleaning, when the nonwoven fabric of this embodiment is used as a wiping cloth, by adjusting the type of fibers contained therein, and / or in improving the overall strength of the nonwoven fabric.

[0096] If the basis weight of the fiber layer X1 is too small, the thickness of the fiber layer X1 will be reduced, and the above-mentioned performance of the fiber layer X1 may not be fully realized. Also, if the basis weight of the fiber layer X1 is too small, the fibers contained in the fiber layer Y may be more likely to appear on the surface of the fiber layer X1. If the fibers contained in the fiber layer Y are hydrophilic fibers, and these hydrophilic fibers appear on the surface of the fiber layer X1, then when the nonwoven fabric of this embodiment is used as a wiping cloth, liquid tends to remain on the surface of the object after wiping and rinsing. If the basis weight of the fiber layer X1 is too large, the function of the fiber layer Y may not be fully realized. Also, when the fiber layer X1 contains hydrophilic fibers, if the basis weight of the fiber layer Y is too small, the intertwining of fibers between the fiber layer X1 and the fiber layer Y may be insufficient, and the mechanical strength of the nonwoven fabric may decrease.

[0097] In a three-layer nonwoven fabric consisting of a fiber layer Y and two fiber layers X1, the ratio of the combined basis weight of the two fiber layers X1 to the basis weight of fiber layer Y may be, for example, 9:1 (X1:Y) to 1:9, particularly 9:1 to 6:4, and more particularly 9:1 to 7:3. The problems when the ratio of the basis weight of fiber layer X1 to the basis weight of fiber layer Y falls outside the above range (when the ratio of either one is too small or too large) are the same as the problems when the basis weight of each fiber layer is too small or too large.

[0098] The overall basis weight of the nonwoven fabric is selected appropriately depending on the application. When using the nonwoven fabric of this embodiment as a wiping cloth, it is selected appropriately depending on the type of object to be wiped, etc. For example, the overall basis weight of the nonwoven fabric is 40 g / m². 2 More than 200g / m 2 The following, in particular, 50g / m 2 More than 150g / m 2 The following is more specifically 60g / m 2 More than 100g / m 2 The following may apply: For example, when nonwoven fabric is used for wiping and polishing mirror-finished furniture or glossy car and motorcycle bodies, the basis weight may be 40 g / m². 2 More than 200g / m 2 The following, in particular, 50g / m 2 More than 150g / m 2 The following may apply: Alternatively, when using nonwoven fabric for wiping and polishing hardwood floors or smooth wall surfaces, the basis weight may be 50 g / m². 2 More than 100g / m 2 The following, in particular, 60g / m 2 More than 90g / m 2 The following is acceptable:

[0099] The nonwoven fabric of this embodiment has a total density of, for example, 0.030 g / cm³. 3 More than 0.200g / cm 3 It may have the following bulk densities, particularly 0.040 g / cm³. 3 More than 0.175g / cm 3 It may have the following bulk density, more particularly 0.050 g / cm³ 3 More than 0.150g / cm 3The nonwoven fabric may have the following bulk densities. The total bulk density of the nonwoven fabric can be determined from the basis weight and thickness (thickness measured by applying a load of 294 Pa). When the nonwoven fabric has a bulk density within the above range, it tends to have excellent wiping performance and allows for wiping / cleaning with light force. If the bulk density is too high, i.e., the bulk of the nonwoven fabric is too low, the surface of the fiber layer X1 becomes dense, making it difficult to wipe / clean with light force. If the bulk density is too low, i.e., the bulk of the nonwoven fabric is too high, the dirt that has been wiped and retained within the nonwoven fabric may fall off, and liquid residue tends to remain.

[0100] In this embodiment, the nonwoven fabric has a configuration in which a fiber layer Y is located between two fiber layers X1, and the fiber layer Y contains cellulose fibers which are hydrophilic fibers. In this case, the tensile strength of the nonwoven fabric in the MD direction (longitudinal or mechanical direction) may be, for example, 20.0 N / 5 cm to 400.0 N / 5 cm, particularly 30 N / 5 cm to 300 N / 5 cm, and more particularly 40 N / 5 cm to 200 N / 5 cm. Furthermore, the tensile strength of the nonwoven fabric in the CD direction (transverse direction) may be, for example, 2.5 N / 5 cm to 100.0 N / 5 cm, particularly 5.0 N / 5 cm to 75.0 N / 5 cm, and more particularly 5.0 N / 5 cm to 50.0 N / 5 cm. When the tensile strength of the nonwoven fabric is within the above range, the shape stability of the nonwoven fabric tends to be improved.

[0101] In this embodiment, the nonwoven fabric has a configuration in which a fiber layer Y is located between two fiber layers X1, and the fiber layer Y contains hydrophilic cellulose fibers. In this case, the elongation of the nonwoven fabric in the MD direction may be, for example, 10% to 100%, and particularly 20% to 80%, and the elongation in the CD direction may be, for example, 40% to 300%, and particularly 75% to 150%. When the elongation of the nonwoven fabric is within the above range, the nonwoven fabric stretches to a certain extent when any force is applied, resulting in excellent operability.

[0102] In this embodiment, the nonwoven fabric has a configuration in which a fiber layer Y is located between two fiber layers X1, and the fiber layer Y contains cellulosic fibers which are hydrophilic fibers. In this case, the 10% elongation stress of the nonwoven fabric in the MD direction may be, for example, 1.0 N / 5 cm or more and 20.0 N / 5 cm or less, particularly 1.5 N / 5 cm or more and 17.5 N / 5 cm or less, and more particularly 2.0 N / 5 cm or more and 15.0 N / 5 cm or less. In addition, the 10% elongation stress of the nonwoven fabric in the CD direction of this embodiment may be, for example, 0.1 N / 5 cm or more and 10.0 N / 5 cm or less, particularly 0.2 N / 5 cm or more and 7.5 N / 5 cm or less, and more particularly 0.4 N / 5 cm or more and 5.0 N / 5 cm or less. When the 10% elongation stress in the MD and CD directions falls within the above range, the handling properties of the nonwoven fabric are improved, which can have a positive impact on, for example, the ease of handling when attaching the wiping cloth to a jig, or on the operability when the user directly grasps the wiping cloth and performs wiping / cleaning.

[0103] In this embodiment, the nonwoven fabric may have the first and second entangled portions arranged in a striped pattern. Furthermore, the striped first and second entangled portions may be meandering. By arranging the first and second entangled portions in a striped pattern, a predetermined pattern is imparted to the nonwoven fabric. This makes it possible to obtain a nonwoven fabric that is more suitable for applications where appearance is important (e.g., cosmetics, surface materials for absorbent articles). Furthermore, such a nonwoven fabric may be more suitable for wiping various types of dirt when used as a wiper to wipe dirt from the human body or articles. This is because the entanglement between fibers and the proportion of fibers A1 to A3 differ between the first and second entangled portions. Below, a modified example of this embodiment will be described, showing a nonwoven fabric having the first and second entangled portions.

[0104] [First confounding section, second confounding section] The first and second entangled portions are both areas where fibers are intertwined and extend along one direction of the nonwoven fabric. Here, the direction in which the first and second entangled portions extend is defined as the X direction, and the direction perpendicular to the X direction is defined as the Y direction. The X direction may be the longitudinal direction (also called the "MD direction") or transverse direction (also called the "CD direction") of the nonwoven fabric, or it may be a direction that forms an angle with the MD direction or the CD direction.

[0105] As described later, the first and second entanglements may be meandering. In that case, if the two types of entanglements meander between two straight lines parallel to the MD direction of the nonwoven fabric, the first and second entanglements shall be considered to extend along the MD direction of the nonwoven fabric, and the X direction shall be the MD direction. Similarly, if the first entanglement meanders between two straight lines parallel to the CD direction of the nonwoven fabric, the first entanglement shall be considered to extend along the CD transverse direction of the nonwoven fabric, and the X direction shall be the CD direction.

[0106] The first and second entangled areas are distinguished by the fact that the patterns they each possess are different. Here, "pattern" includes "no pattern." "No pattern" refers to something that does not convey a sense of design, and may have, for example, unevenness in the surface texture that occurs unavoidably during web formation, or nozzle lines that occur unavoidably during water flow entanglement processing, but without any intentional pattern being added. More specifically, if the longest dimension of a protrusion, recess, or opening (excluding the dimension in a direction that extends continuously in one direction, such as a nozzle line) is 0.1 mm or less, then such protrusion, recess, or opening is not considered to form a pattern.

[0107] The first entangled portion may be patternless or may have a pattern. When the nonwoven fabric of this embodiment is manufactured by performing a pattern-forming entanglement process after an overall entanglement process, the first entangled portion has a pattern determined by the support used during the overall entanglement process. If a support with a large mesh count is used in the overall entanglement process, the first entangled portion is formed as patternless.

[0108] The second entanglement area may be patternless or may have a pattern. By varying the patterns of the first and second entanglement areas, the nonwoven fabric exhibits a unique design effect that is not simply a striped pattern.

[0109] The Y-direction dimension of each first entanglement (hereinafter referred to as "width" for convenience) may be, for example, 2 mm or more and 200 mm or less, particularly 3.5 mm or more and 100 mm or less, more particularly 4 mm or more and 50 mm or less, even more particularly 5 mm or more and 30 mm or less, or 5 mm or more and 15 mm or less. In a single first entanglement, the width may be constant or not.

[0110] In nonwoven fabrics, first entanglements of different widths may exist. For example, narrow first entanglements (e.g., 2 mm to 5 mm) and wide first entanglements (e.g., 6 mm to 15 mm) may be arranged alternately. Alternatively, narrow first entanglements (e.g., 2 mm to 3 mm), medium first entanglements (e.g., 4 mm to 5 mm), and wide first entanglements (e.g., 6 mm to 15 mm) may be arranged in the order of narrow / medium / wide or narrow / wide / medium.

[0111] The width of each second confluence may be 2 mm or more and 200 mm or less, particularly 3.5 mm or more and 100 mm or less, more particularly 4 mm or more and 50 mm or less, even more particularly 5 mm or more and 30 mm or less, or 5 mm or more and 15 mm or less. In a single second confluence, the width may be constant or not.

[0112] In nonwoven fabrics, second entanglements of different widths may exist. For example, narrow (e.g., 2 mm to 5 mm) second entanglements and wide (e.g., 6 mm to 15 mm) second entanglements may be arranged alternately. Alternatively, narrow (e.g., 2 mm to 3 mm) second entanglements, medium (e.g., 4 mm to 5 mm) second entanglements, and wide (e.g., 6 mm to 15 mm) second entanglements may be arranged in the order of narrow / medium / wide or narrow / wide / medium.

[0113] In a nonwoven fabric, the first entanglement portion may be linear or meandering. If the first confluence is meandering, the length of the meander per period (i.e., wavelength) may be 5 mm or more. The length of the meander per period is determined as follows: i) As shown in Figure 2, the direction parallel to the line perpendicular to the X direction 31 on which the first entangled portion 42 extends (i.e., the Y direction) is defined as the orthogonal direction, the direction extending towards the "+" side is defined as the positive orthogonal direction 32a, and the direction extending towards the "-" side is defined as the negative orthogonal direction 32b. ii) At point e, where the meandering of the first confluence 42, which was moving toward the negative orthogonal direction 32b (since the first confluence 42 has width, we focus on the movement of one end in the width direction (the left end in the figure)), changes toward the positive orthogonal direction 32a, a straight line 33 perpendicular to the length direction 31 is drawn. iii) At point f, where the meandering of the first entangled portion 42, which was proceeding from point e toward the positive orthogonal direction 32a, progresses toward the negative orthogonal direction 32b and then changes again toward the positive orthogonal direction 32a, a straight line 34 perpendicular to the length direction 31 is drawn. iv) The distance l between line 33 and line 34 is defined as the length of the meander per period. At the point where the meandering of the first entanglement 42 changes from a negative orthogonal direction 32b to a positive orthogonal direction 32a, if the first entanglement 42 moves in a straight line in the longitudinal direction 31 (for example, in the case of a meandering like a rectangular wave), then straight lines 33 and 34 perpendicular to the longitudinal direction 31 are drawn at the midpoint of the straight portion. In Figure 2, reference numeral 41 indicates a second entanglement formed between the first entanglement 42s.

[0114] In this embodiment, the upper limit of the wavelength may be 200 mm. The wavelength is particularly between 10 mm and 150 mm, and more particularly between 30 mm and 100 mm. This allows the meandering pattern to be clearly visible in the nonwoven fabric.

[0115] The meandering of the first confluence is preferably such that it has an amplitude of 1 mm or more. The amplitude is determined as follows. i) As shown in Figure 2, let g be a point on the straight line 33 described above that divides the width of the first entanglement portion 42 into equal parts. ii) At point i, where the meandering of the first entangled portion 42, which was progressing in the positive orthogonal direction 32a, changes to the negative orthogonal direction 32b, a straight line 35 is drawn perpendicular to the length direction 31, and point h is located on this straight line 35 and divides the width of the first entangled portion 42 into equal parts. iii) The amplitude is defined as the distance j between a straight line 36 that includes point g and is parallel to the length direction 31, and a straight line 37 that includes point i and is parallel to the length direction. The upper limit of the amplitude may be 200 mm. The amplitude is particularly between 2 mm and 150 mm, more particularly between 5 mm and 100 mm, and even more particularly between 10 mm and 50 mm.

[0116] The meandering of the first entanglement may have different lengths per period, different amplitudes like a damped wave, and these meanders may be repeated regularly. A preferred configuration of the meandering is one in which the length of the meandering per period is the same and the amplitude is the same, i.e., a repetition of the same pattern. Such a meandering first entanglement gives an orderly impression. Furthermore, such a meandering first entanglement does not give the impression that the design differs greatly between products when the nonwoven fabric is cut as appropriate.

[0117] The ratio of the length (wavelength) to the amplitude per period of the meander (wavelength / amplitude) may be, for example, between 1 and 15, particularly between 1.5 and 12, and more particularly between 2 and 8. If the value of the wavelength-to-amplitude ratio is less than 1, or greater than 15, it may be difficult to recognize that the first confluence is meandering.

[0118] If the nonwoven fabric has only a first and a second confluence, and the first confluence is meandering, then the second confluence adjacent to the first confluence will also meander. In this case, the length and amplitude of the meandering per period of the second confluence are determined by those of the first confluence. Therefore, a description of the length and amplitude of the meandering per period of the second confluence is omitted here.

[0119] The ratio of the proportion of fibers A1, A2, and A3 included as fiber A in the second entanglement to the proportion of the proportion of fibers A1, A2, and A3 included as fiber A in the first entanglement is preferably as follows: (i) Fiber A1 (second entanglement part / first entanglement part): 1.0 or more and 2.0 or less, especially 1.0 or more and 1.5 or less (ii) Fiber A2 (second entanglement part / first entanglement part): 0.5 to 2.0, especially 0.6 to 1.5 (iii) Fiber A3 (second entanglement part / first entanglement part): 0.2 or more and 1.0 or less, especially 0.4 or more and 0.9 or less

[0120] (Manufacturing method for nonwoven fabrics) Next, the manufacturing method of the nonwoven fabric will be described. The nonwoven fabric of this embodiment is, for example, Prepare a fiber web containing 10% to 90% by mass of irregularly shaped cross-section fibers having multiple protrusions in their cross-section, and 10% to 90% by mass of segmented composite fibers. This process involves subjecting a fiber web to an entanglement treatment using a high-pressure fluid flow of 1 MPa to 10 MPa, thereby causing the fibers to become entangled with each other. It can be manufactured by a specific manufacturing method.

[0121] When the nonwoven fabric is a laminated nonwoven fabric containing fiber layer X1 and fiber layer Y, the nonwoven fabric is, Prepare a first fiber web containing 10% to 90% by mass of irregularly shaped cross-section fibers having multiple protrusions in their cross-section, and 10% to 90% by mass of segmented composite fibers. Prepare a second fiber web that is different from the first fiber web, in particular a second fiber web containing 50% by mass or more of hydrophilic fibers with a fiber length of 20 mm or more and 100 mm or less. Prepare a laminated web by overlapping two fiber webs. The laminated web is subjected to an entanglement treatment using high-pressure fluid flow to entangle the fibers. including, It can be manufactured by a manufacturing method. In this case, the first fiber web constitutes the fiber layer X1, and the second fiber web constitutes the fiber layer Y.

[0122] When the laminated structure is configured such that a fiber layer Y is located between two fiber layers X1, a laminated web is prepared in which a second fiber web is located between first fiber webs, and this is subjected to an entanglement process to entangle the fibers.

[0123] The first fiber web and the second fiber web can be manufactured by known methods. The form of each fiber web may be selected from, for example, card webs such as parallel webs, cross webs, semi-random webs and random webs, airlaid webs, wet papermaking webs, and spunbond webs. The forms of each fiber web may be different from each other; for example, two first fiber webs may have the same form but a different form from the second fiber web, or two first fiber webs may have different forms, with one of them having the same form as the second fiber web.

[0124] In high-pressure fluid flow processing, the high-pressure fluid is, for example, a high-pressure gas such as compressed air, and a high-pressure liquid such as high-pressure water. In the manufacture of nonwoven fabrics, water flow entanglement processing using high-pressure water as the high-pressure fluid is often used, and in this embodiment as well, water flow entanglement processing is preferably used from the viewpoint of ease of implementation. Below, a manufacturing method when high-pressure water (hereinafter also simply referred to as "water flow") is used as the high-pressure fluid will be described.

[0125] The water entanglement treatment is carried out by placing a laminated fiber web on a support and spraying a columnar stream of water onto it. For example, the support is preferably a plain weave support with a mesh size of 80 or more and 100 or less. The water entanglement treatment may be carried out by spraying a water stream with a pressure of 1 MPa or more and 7 MPa onto the front and back surfaces of the laminated fiber web 1 to 5 times each from a nozzle having orifices with a hole diameter of 0.05 mm or more and 0.5 mm or less spaced at intervals of 0.3 mm or more and 1.5 mm or less. The water pressure is preferably 1 MPa or more and 10 MPa or less, and more preferably 1 MPa or more and 9.5 MPa or less. The nonwoven fabric of this embodiment can be obtained by spraying a stream of water and then performing a drying process.

[0126] During the water flow entanglement treatment, at least a portion of the segmented composite fibers contained in the first fiber web splits to form ultrafine fibers derived from the segmented composite fibers, and in some cases, the convex portions of the irregularly shaped cross-section fibers peel off to form fibers derived from the irregularly shaped cross-section fibers. The greater the water flow pressure and / or the more times the water flow is sprayed, the easier it is for the ultrafine fibers and fibers derived from the irregularly shaped cross-section fibers to form.

[0127] In manufacturing the nonwoven fabric of this embodiment, it is preferable that the process of bonding the fibers together is not included. If the fibers are bonded together, the bonded areas become hard, and when the nonwoven fabric is used as a wiping cloth, the bonded areas may scratch the surface of the object. In the nonwoven fabric of this embodiment, the divided composite fibers contained in the fiber layer X (fiber web, or first fiber web) divide to form ultrafine fibers, which contribute to good entanglement between the fibers, and if the fiber layer X and / or fiber layer Y (second fiber web) contain hydrophilic fibers, these also contribute to good entanglement. Therefore, the nonwoven fabric of this embodiment can be provided as a nonwoven fabric with mechanical strength that can be used as a wiping cloth without bonding the fibers together.

[0128] In the method for manufacturing a nonwoven fabric according to this embodiment, the entanglement treatment may be carried out by spraying a high-pressure fluid stream, particularly a water stream, onto the fiber web such that areas where a high-pressure fluid stream is sprayed from two or more consecutive orifices of a nozzle and areas where a high-pressure fluid stream is not sprayed onto the fiber web are alternately located. By such an entanglement treatment, a nonwoven fabric can be obtained in which the first entangled portion and the second entangled portion are arranged in a striped pattern.

[0129] Specifically, in a method for manufacturing a nonwoven fabric in which the first and second entangled portions are arranged in a striped pattern, a water flow entanglement treatment is partially performed along the mechanical direction (MD direction) of the support while the nonwoven fabric is placed on a specific support, such that portions where a high-pressure fluid flow is injected from two or more consecutive orifices of a nozzle onto the fiber web and portions where a high-pressure fluid flow is not injected onto the fiber web are alternately positioned (hereinafter referred to as the "pattern-forming entanglement treatment"). In the pattern-forming entanglement treatment, portions where the water flow does not hit and portions where the water flow hits are alternately arranged along the CD direction of the nonwoven fabric.

[0130] It is desirable to subject the entire fiber web to a water-flow entanglement treatment (hereinafter referred to as "overall entanglement treatment") before the pattern-forming entanglement treatment. The overall entanglement treatment is carried out under the same treatment conditions throughout the entire fiber web. Furthermore, the overall entanglement treatment may be carried out in such a way that the fiber web after the entanglement treatment does not have a pattern, i.e., it becomes patternless. By performing the overall entanglement treatment, the fibers are entangled to a certain extent in advance, forming the first entangled parts in the resulting nonwoven fabric, and then in the subsequent pattern-forming entanglement treatment, a second entangled part can be formed as a part different from the first entangled part. The overall entanglement treatment can be carried out in the same way as the water-flow entanglement treatment described above.

[0131] In the pattern formation confounding process, multiple orifices are divided into multiple groups, and the length of each group in the longitudinal direction (for example, the length in the same direction as the CD direction) may be particularly 3.5 mm or more and 100 mm or less, more particularly 4 mm or more and 50 mm or less, even more particularly 5 mm or more and 30 mm or less, or 5 mm or more and 15 mm or less. In one second confounding section, the width may be constant or not.

[0132] When performing an overall entanglement treatment before a pattern-forming entanglement treatment, it is preferable to perform the pattern-forming entanglement treatment with a greater hydraulic pressure energy than the overall entanglement treatment. This allows for adjusting the degree of division (or splitting) of the divided composite fibers, thereby adjusting the proportions of fibers A1, A2, and A3 in the second entangled portion formed by the pattern-forming entanglement treatment to a predetermined range in relation to those in the first entangled portion.

[0133] The water pressure energy can also be adjusted by the configuration of the nozzles used for pattern formation and entanglement. For example, the pitch (spacing) between orifices is preferably 80% or less of the pitch between orifices of the nozzles used for overall entanglement. More preferably, it is 60% or less, and even more preferably, 50% or less. Furthermore, the water pressure used in the pattern formation entanglement treatment is preferably 100% or more of the maximum water pressure used in the overall entanglement treatment. More preferably, it is 110% or more.

[0134] The pattern-forming entanglement process may also be carried out by placing a member between the fiber web and a nozzle, which has a plurality of holes arranged in a line perpendicular to the direction of progression of the fiber web and which prevents the high-pressure fluid from passing through areas other than the holes, and injecting a high-pressure fluid stream from the nozzle. As a result, during the water flow entanglement process, areas that are not exposed to the water flow are continuously formed in the MD direction on the fiber web, and these areas are formed at intervals in the CD direction. The areas that were not exposed to the water flow and the areas where the fibers were rearranged by the water flow become the first entangled areas and the second entangled areas, respectively, in the resulting nonwoven fabric, and the first and second entangled areas are arranged alternately in the CD direction to form a striped pattern.

[0135] More specifically, when using a nozzle in which orifice groups are provided at predetermined intervals, only the water flow ejected from the orifice groups acts on the web. Therefore, a high-pressure water flow with the energy necessary to form a pattern corresponding to the pattern-forming support acts only on the portion of the web corresponding to the orifice group. In this nozzle, the orifice groups are provided over a section corresponding to the width of the second entanglement. The spacing of the orifice groups corresponds to the width of the first entanglement. Such a nozzle may be one in which the orifices are plugged in the section corresponding to the first entanglement, in a nozzle designed to apply water flow over the entire surface, as described in relation to the overall entanglement process. A single orifice group preferably consists of two or more orifices. When there are two or more orifices, a pattern corresponding to the pattern-forming support can be formed more clearly in the second entanglement. The spacing between adjacent orifices in an orifice group may be, for example, 0.2 mm to 1.5 mm.

[0136] In the method of forming a second entanglement using a perforated member, only the water flow passing through the holes acts on the web. Therefore, a high-pressure water flow with the energy necessary to form a pattern corresponding to the pattern-forming support acts only on the portion of the web corresponding to the hole. The perforated member is not particularly limited as long as it has multiple holes. For example, the material may be synthetic resin or metal. Also, the shape may be plate-shaped or roll-shaped, etc., and can be appropriately selected according to the water flow entanglement treatment apparatus.

[0137] Multiple holes in the perforated member are formed along a direction perpendicular to the direction of travel of the support. Each hole may have a dimension of, for example, 2 mm or more, particularly 3 mm to 50 mm, and more particularly 5 mm to 30 mm, in the direction perpendicular to the direction of travel of the support. When forming a second entanglement with a different width, holes of different dimensions are formed in a single perforated member according to the width of the second entanglement to be obtained. The spacing between adjacent holes in the perforated member may be, for example, 2 mm or more, particularly 3 mm to 50 mm, and more particularly 5 mm to 30 mm. The spacing between adjacent holes determines the width of the first entanglement, so it is appropriately selected according to the width of the first entanglement to be obtained. The shape of the holes is not particularly limited and may be, for example, circular, semicircular, elliptical, polygonal (triangle or quadrilateral), star polygon, cross-shaped, or slit-shaped (straight or curved).

[0138] When using a perforated member, the nozzle is not particularly limited and may be the same as that described in relation to the overall entanglement treatment. The distance between the perforated member and the nozzle may be, for example, 1 mm or more. If the distance between the perforated member and the nozzle is less than 1 mm, the perforated member and the nozzle may come into contact, and one or both may be damaged. On the other hand, the distance between the perforated member and the nozzle may be, for example, 30 mm or less. If the distance between the perforated member and the orifice exceeds 30 mm, the energy of the water flow may decrease, and the pattern may not be formed properly. The distance between the perforated member and the fiber web may be, for example, 5 mm or more and 50 mm or less. If the distance between the perforated member and the fiber web exceeds 50 mm, the energy of the water flow may decrease, and the pattern may not be formed properly.

[0139] The range of water pressure that may be used during the pattern formation entanglement treatment is as described in relation to the overall entanglement treatment. Pattern formation entanglement treatment is usually performed by spraying a stream of water onto one side of the fiber web after the overall entanglement treatment. The pressure during the pattern formation entanglement treatment may be particularly between 1 MPa and 15 MPa, and more particularly between 2 MPa and 10 MPa.

[0140] In the pattern-forming entanglement process, by fixing the position of the nozzle or perforated member and advancing the pattern-forming support along the longitudinal or transverse direction (usually the longitudinal direction) of the fiber web, a nonwoven fabric is obtained in which a plurality of first entanglements and a plurality of second entanglements extend linearly in the longitudinal or transverse direction of the nonwoven fabric.

[0141] In the pattern-forming entanglement process, vibrating a nozzle or perforated member and advancing the pattern-forming support along the longitudinal or transverse direction (usually the longitudinal direction) of the fiber web yields a nonwoven fabric with a meandering configuration of first and second entanglements. Here, "vibration" means moving the nozzle or perforated member back and forth along a certain direction. "Vibration" includes not only moving back and forth in a straight line, but also moving back and forth along an elliptical orbit with a certain direction as its major axis.

[0142] The vibration direction of the nozzle or perforated member may be appropriately selected from the longitudinal (MD) direction, transverse (CD) direction, and diagonal direction of the web. Here, "diagonal direction" means a direction that forms an angle with the longitudinal or transverse direction along the surface direction of the web, in the range of 0 degrees to less than 90 degrees. Considering ease of manufacturing, the vibration direction is preferably the transverse direction, or a direction that forms an angle with the transverse direction in the range of 0 degrees to 45 degrees or less.

[0143] The amplitude of the vibration of the nozzle or perforated member will be approximately the same as the amplitude of the first entanglement in the resulting nonwoven fabric (as described above). Therefore, the amplitude of the vibration of the nozzle or perforated member is determined according to the amplitude of the first entanglement to be obtained. The length of the meandering per period of the first entanglement is determined by the vibration velocity of the nozzle or perforated member and the advancement speed of the pattern-forming support. Therefore, the vibration velocity of the nozzle or perforated member is determined according to the length of the meandering per period of the first entanglement to be obtained, taking into account the advancement speed of the pattern-forming support.

[0144] The vibration speed of the perforated member can be increased to approximately 100 m / min. By increasing the vibration speed of the perforated member, the difference between the width X at the turning points of the entanglement sections, such as the first and second entanglement sections, and the width Y at other points can be increased.

[0145] (Wiping cloth) Next, a wiping cloth using the nonwoven fabric of this embodiment as a base material will be described as the wiping cloth of this embodiment. The wiping cloth in this embodiment may be a wet-type wiping cloth provided in a liquid-impregnated state. In this case, the amount of liquid impregnated may be, for example, 10 to 90 parts by mass, more particularly 15 to 85 parts by mass, and more particularly 20 to 80 parts by mass, per 100 parts by mass of nonwoven fabric. The liquid to be impregnated may contain water and cleaning components (e.g., surfactants), and may also contain a finishing agent if the wiping cloth is used to apply a finishing agent. The finishing agent may be, for example, an antibacterial agent or a polishing agent.

[0146] The wiping cloth in this embodiment may be a dry type wiping cloth that is not impregnated with liquid. When provided as a dry type wiping cloth, a finishing agent can be applied to the object even if it is a dry type by pre-applying a finishing agent to the nonwoven fabric and drying it. Alternatively, the dry type wiping cloth may be provided so that the user can freely impregnate it with a cleaning agent or the like depending on the object.

[0147] The wiping cloths of this embodiment are specifically provided as, for example, various household wiping cloths, more specifically, floor wiping cloths that can be divided into those for flooring and those for tatami mats, wiping cloths for glass products, wiping cloths for general household appliances, wiping cloths for sanitary ware such as washbasins and toilet bowls, wiping cloths for cooking utensils whose main purpose is to remove oil splatters and burnt-on food, wiping cloths for the bodies of various vehicles such as passenger cars and motorcycles, and industrial wiping cloths for removing oily stains such as grease that adhere to machinery.

[0148] (Other uses) In addition to being a base material for wiping cloths, the nonwoven fabric of this embodiment can be used as a base material for various sheets such as surface sheets, second sheets, and back sheets of absorbent articles, filters, sanitary masks, gauze, face masks impregnated with cosmetics, adhesives, packaging materials, mats, cushioning materials, tablecloths, carpet backings, wallpaper, and more. [Examples]

[0149] The present invention will be described in detail below with reference to examples and comparative examples, but these examples represent only one aspect of the present invention, and the present invention is not limited in any way by these examples.

[0150] (Irregularly shaped cross-section fiber 1) Polypropylene resin (manufactured by Nippon Polypropylene Co., Ltd., SA03 (product name), melting point: 160°C, MFR230: 30g / 10min) was prepared. Using a spinning nozzle with a four-leaf clover-shaped nozzle hole, this was melt-extruded at a spinning temperature of 270°C and taken up at a take-up speed of 1000m / min to produce a spun filament (undrawn) with a fineness of 4dtex. The spun filament was wet-drawn 2.7 times in 90°C hot water, and then the continuous fibers were cut to a fiber length of 51mm to obtain a deformed cross-section fiber 1 with a fineness of 1.7dtex (fiber diameter when converted to a round cross-section fiber of the same area: approximately 15.5μm). The tensile strength of this fiber was 4.82 cN / dtex. The fiber strength (tensile strength) was measured according to JIS-L-1015, using a tensile testing machine, and was recorded as the load value at which the fiber broke when the gripping distance of the sample was 20 mm (the same method was used for the following fibers).

[0151] The irregularly shaped fiber 1, as illustrated in Figure 1, had a four-lobed cross-sectional shape with four convex portions. The tips of these convex portions were approximately curved, and the width of the root portion towards the center of the fiber was smaller than the maximum width of the tip portion. The maximum width Wt at the tip of the convex portion was 8.6 μm, the width Wb at the root portion was 4.8 μm, the ratio Wt / Wb (the ratio of the maximum width Wt to ​​the width Wb at the root portion) was 1.79, the length Lt (the length from the center point of the root portion of the convex portion to the tip) was 9.4 μm, and the ratio Lt / Wb (the ratio of the length Lt to the width Wb at the root portion) was 1.96. In some areas, the convex portions were deformed from the root, the distance between adjacent convex portions was not constant, and in some fibers, a portion of the root portion of the convex portion was peeled off.

[0152] Furthermore, the maximum width (Wt), length (Lt), maximum width (Wt), and width (Wb) at the base of the protrusions in the fiber cross-section of the irregularly shaped fibers were measured using the following procedure. First, a nonwoven fabric containing irregularly shaped cross-section fibers from Example 1 was prepared, and the nonwoven fabric was cut with a sharp blade perpendicular to the machine direction (MD direction) of the nonwoven fabric. The cut surface obtained by the above operation was observed with a scanning electron microscope (SEM, acceleration voltage: 5.00kV, magnification: 200x). From the captured SEM images, five irregularly shaped cross-section fibers were selected from one SEM image. Using the image analysis software WinROOF (manufactured by Mitani Corporation), the distances of the selected fibers corresponding to the length of the convex portion (Lt), the maximum width of the convex portion (Wt), and the width of the base portion of the convex portion (Wb), as shown in the schematic fiber cross-section diagram of the irregularly shaped cross-section fiber in Figure 1, were measured. Measurements were taken on a total of three SEM images, and the values ​​from each of the 15 points were averaged to determine the result.

[0153] (Irregularly shaped cross-section fiber 2) Polypropylene resin (manufactured by Nippon Polypropylene Co., Ltd., SA03 (product name), melting point: 160°C, MFR230: 30g / 10min) was prepared. Using a spinning nozzle with a four-leaf clover-shaped nozzle hole, it was melt-extruded at a spinning temperature of 270°C and taken up at a take-up speed of 533m / min to produce a spun filament (undrawn) with a fineness of 7.5 dtex. The spun filament was wet-drawn 2.7 times in 90°C hot water, and the continuous fibers were cut to a fiber length of 51 mm to obtain a deformed cross-section fiber 2 with a fineness of 3.3 dtex (fiber diameter when converted to a round cross-section fiber of the same area: approximately 21.5 μm). The tensile strength was 3.3 cN / dtex.

[0154] The irregularly shaped fiber 2, as illustrated in Figure 1, had a four-lobed cross-sectional shape with four protrusions. The tips of these protrusions were approximately curved, and the width of the root portion towards the center of the fiber was smaller than the maximum width of the tip portion. The maximum width Wt at the tip of the protrusion was 10.9 μm, the width Wb at the root portion was 9.3 μm, the ratio Wt / Wb (the ratio of the maximum width Wt to ​​the width Wb at the root portion) was 1.18, the length Lt (the length from the center point of the root portion to the tip of the protrusion) was 9.5 μm, and the ratio Lt / Wb (the ratio of the length Lt to the width Wb at the root portion) was 1.02. In some areas, the protrusions were deformed from the root, the distance between adjacent protrusions was not constant, and in some fibers, a portion of the root portion of the protrusion was peeled off.

[0155] (Split-type composite fiber 1) As a segmented composite fiber 1, a round cross-section 8-segment fiber (manufactured by Daiwa Spinning Co., Ltd., trade name DFS(SH)) was prepared, with a fiber length of 51 mm and a fineness of 2.2 dtex, having a total of 16 sections, in which wedge-shaped sections made of polyethylene terephthalate resin and wedge-shaped sections made of high-density polyethylene resin are arranged alternately in a chrysanthemum pattern in the cross-section. In segmented composite fiber 1, the volume ratio of polyethylene terephthalate resin (PET) to high-density polyethylene resin (HDPE) was 5:5 (PET:HDPE). The tensile strength was 2.62 cN / dtex.

[0156] (Split-type composite fiber 2) As a segmented composite fiber 2, a round cross-section 16-segment fiber (manufactured by Daiwa Spinning Co., Ltd., product name DF-1) was prepared, with a fiber length of 45 mm and a fineness of 3.3 dtex, having a total of 16 sections, in which wedge-shaped sections made of polyethylene terephthalate resin and wedge-shaped sections made of polypropylene resin are arranged alternately in a chrysanthemum pattern in the cross-section. In segmented composite fiber 1, the volume ratio of polyethylene terephthalate resin (PET) to polypropylene resin (PP) was 5:5 (PET:PP). The tensile strength was 2.45 cN / dtex.

[0157] (Split-type composite fiber 3) As a segmented composite fiber 3, a round cross-section 16-segment fiber (manufactured by Yamato Spinning Co., Ltd., product name DF-7) was prepared, with a fiber length of 51 mm and a fineness of 2.0 dtex, having a total of 16 sections, in which wedge-shaped sections made of polypropylene resin and wedge-shaped sections made of high-density polyethylene resin are arranged alternately in a chrysanthemum pattern in the cross-section. In segmented composite fiber 1, the volume ratio of polypropylene resin (PP) to high-density polyethylene resin (HDPE) was 5:5 (PP:HDPE). The tensile strength was 5.13 cN / dtex.

[0158] (Split-type composite fiber 4) As a segmented composite fiber 4, a 22-section circular fiber (manufactured by Kuraray Co., Ltd., product name: Lamp) was prepared, with a fiber length of 51 mm and a fineness of 3.8 dtex, having a total of 22 sections, in which approximately rectangular sections made of polyethylene terephthalate resin and approximately rectangular sections made of nylon resin are arranged in layers in the cross-section. In the segmented composite fiber 4, the volume ratio of polyethylene terephthalate resin to nylon resin was 5:5 (PET:Ny). The tensile strength was 2.40 cN / dtex.

[0159] (Undivided fiber 1) As undivided fiber 1, a single fiber made of polyethylene terephthalate with a fiber length of 51 mm and a fineness of 2.2 dtex (manufactured by Toray Industries, Inc., product name T201) was prepared.

[0160] (Hydrophilic fiber 1) As a hydrophilic fiber, we prepared a rayon fiber with a fiber length of 40 mm and a fineness of 1.7 dtex (manufactured by Daiwabo Rayon Co., Ltd., product name Corona).

[0161] [Example 1] A mixture of 75% by mass of irregularly shaped cross-section fibers 1 and 25% by mass of segmented composite fibers 1 is processed using a parallel carding machine to obtain a basis weight of 30 g / m². 2 A parallel web was prepared as the first fiber web. Separately, using only hydrophilic fiber 1, a web with a basis weight of 10 g / m was prepared. 2 A parallel web was fabricated as the second fiber web. The second fiber web was placed on top of the first fiber web, and then the first fiber web was placed on top of that to create a three-layer laminated web.

[0162] The laminated web was subjected to a water-jet entanglement treatment to entangle the fibers. The water-jet entanglement treatment was performed by spraying a columnar water stream at 3.0 MPa twice onto one side of the laminated web (the surface of one first fiber web) and then spraying a columnar water stream at 3.0 MPa twice onto the other side (the surface of the other first fiber web) using a nozzle with orifices of 0.08 mm in diameter spaced at 0.6 mm intervals. After the water-jet entanglement treatment, the laminated web was dried with hot air set to 80°C using a hot air perforation dryer to obtain a nonwoven fabric.

[0163] [Example 2] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 25% by mass of irregularly shaped cross-section fibers 1 and 75% by mass of segmented composite fibers 1.

[0164] [Example 3] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 25% by mass of irregularly shaped cross-section fibers 1 and 75% by mass of segmented composite fibers 2.

[0165] [Example 4] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 25% by mass of irregularly shaped cross-section fibers 1 and 75% by mass of segmented composite fibers 3.

[0166] [Comparative Example 1] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was made using only the irregularly shaped cross-section fiber 1.

[0167] [Comparative Example 2] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 25% by mass of irregularly shaped cross-section fibers 1 and 75% by mass of undivided (single) fibers 1.

[0168] [Comparative Example 3] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 25% by mass of irregularly shaped cross-section fibers 1 and 75% by mass of segmented composite fibers 4.

[0169] The nonwoven fabrics of Examples 1-4 and Comparative Examples 1-3 were evaluated as follows, and the number of fibers A1-A3 contained in the fiber layer X1, Smax, and the number of fibers 1-3 derived from the split composite fibers were measured.

[0170] [Example 5] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 50% by mass of irregularly shaped cross-section fibers 1 and 50% by mass of segmented composite fibers 1.

[0171] [Example 6] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was prepared by mixing 25% by mass of irregularly shaped cross-section fibers 2 and 75% by mass of segmented composite fibers 3.

[0172] [Example 7] A mixture of 20% by mass of irregularly shaped cross-section fibers 1 and 80% by mass of segmented composite fibers 1 is processed using a parallel carding machine to obtain a basis weight of 30 g / m². 2A parallel web was prepared as the first fiber web. Separately, using only hydrophilic fiber 1, a web with a basis weight of 10 g / m was prepared. 2 A parallel web was fabricated as the second fiber web. The second fiber web was placed on top of the first fiber web, and then the first fiber web was placed on top of that to create a three-layer laminated web.

[0173] The laminated web was subjected to a water-flow entanglement treatment to entangle the fibers. The water-flow entanglement treatment was performed by using a nozzle with orifices of 0.08 mm in diameter spaced 0.6 mm apart, injecting a columnar water stream at 3.0 MPa twice onto one side of the laminated web (the surface of one first fiber web) and then injecting a columnar water stream at 3.0 MPa twice onto the other side (the surface of the other first fiber web) to perform overall entanglement.

[0174] Next, a pattern-forming entanglement treatment was performed. Specifically, using a nozzle with orifices of 0.08 mm in diameter spaced at 0.3 mm intervals, a perforated member (each hole being square in shape in a direction perpendicular to the direction of travel of the support, with a spacing of 84 mm between the holes) was vibrated along the lateral direction of the laminated web at an amplitude of 25 mm and vibration speed of 2.0 m / min while a columnar water stream of 2.7 MPa was sprayed once, so that a first entanglement section with a width of 84 mm and a second entanglement section with a width of 6 mm were alternately formed in the lateral direction (CD direction). The laminated web after the water flow entanglement treatment was dried with hot air set to 80°C using a hot air penetration dryer to obtain the nonwoven fabric of Example 7.

[0175] [Comparative Example 4] A nonwoven fabric was obtained using the same procedure as in Example 1, except that the first fiber web was made using only the segmented composite fiber 1. Tables 1-6 show the evaluation results of the nonwoven fabrics obtained in each example and comparative example.

[0176] [Thickness] The thickness of the nonwoven fabric was measured as follows: Using a thickness measuring instrument (THICKNESS GAUGE Model CR-60A (product name) manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), 0.3 kPa (1 cm) was measured on the nonwoven fabric.2 Under conditions where a load of 3g (weight per unit area) is applied, and 1.96kPa (1cm²) is applied to the nonwoven fabric. 2 The thickness of the nonwoven fabric was measured while a load of 20g (per unit) was applied.

[0177] [Inspector] The basis weight of the nonwoven fabric was calculated by measuring the mass of a sample of a predetermined size without wetting it with cosmetics or water. Specifically, a sample measuring 15 cm vertically (MD direction / flow direction) x 15 cm horizontally (CD direction / machine direction) was taken from the nonwoven fabric to be measured, and its mass was measured. The mass of the measured nonwoven fabric sample and the area of ​​the sample (225 cm²) were then calculated. 2 The basis weight of the nonwoven fabric was calculated from the following. For the basis weight measurement, three samples were taken from the same nonwoven fabric, and the average of the basis weights measured for each sample was taken as the basis weight (measured value) of the nonwoven fabric.

[0178] [Specific volume] The specific volume was measured as follows. First, the basis weight of the nonwoven fabric to be measured was calculated using the method described above. Next, the thickness of the nonwoven fabric sample used to calculate the basis weight was measured using the method described above. The specific volume of the nonwoven fabric was calculated from the measured basis weight and thickness. For the measurement of specific volume, similar to the measurement of basis weight, three samples were taken from the same nonwoven fabric, and the average value of the specific volume measured for each sample was taken as the specific volume (measured value) of the nonwoven fabric.

[0179] [bulk density] The bulk density was measured as follows. First, the basis weight (ply weight) of the nonwoven fabric to be measured was calculated using the method described above. Next, the thickness of the nonwoven fabric sample used to calculate the basis weight was measured using the method described above. The specific volume of the nonwoven fabric was calculated from the measured basis weight and thickness. For the measurement of bulk density, similar to the measurement of basis weight, three samples were taken from the same nonwoven fabric, and the average value of the specific volume measured for each sample was taken as the bulk density (measured value) of the nonwoven fabric.

[0180] [Thickness reduction rate] The thickness reduction rate was measured as follows. First, prepare three samples of nonwoven fabric to measure the thickness reduction rate. Next, when measuring the thickness of the nonwoven fabric, the load applied to the nonwoven fabric should be 0.3 kPa (1 cm 2 Thickness (T) measured at 3g load per unit 0.3 ) Measure. Next, the thickness was measured in a different location, and the load applied to the nonwoven fabric was 1.96 kPa (1 cm). 2 (20g per unit) and measure the thickness (T 1.96 ). The thickness (T) was measured with a load of 0.3 kPa applied to the nonwoven fabric. 0.3 ) and the thickness (T) measured with a load of 1.96 kPa applied to the nonwoven fabric. 1.96 The thickness reduction rate of the nonwoven fabric is calculated using the following formula. ·Thickness reduction rate (%)=100×(T 0.3 -T 1.96 ) / T 0.3 The thickness reduction rate of the nonwoven fabric was measured three times, and the average value was used as the thickness reduction rate for that nonwoven fabric.

[0181] [Stretch strength in dry state] The tensile strength, elongation, and 10% modulus strength of the nonwoven fabric in its dry state were measured as follows, in accordance with JIS L 1913:2010 6.3. First, three samples are taken from the nonwoven fabric whose strength and elongation in a dry state are to be measured. Next, a constant-speed tension tensile testing machine was used to perform tensile tests on the sample pieces under the conditions of a width of 5 cm, a gripping distance of 10 cm, and a tensile speed of 30 ± 2 cm / min. The load value at break (tensile strength), elongation, and 10% modulus strength (the force required to elongate by 10%, also called the stress at 10% elongation) were measured. The tensile tests were performed with the longitudinal (MD direction) and transverse (CD direction) of the nonwoven fabric as the tensile direction. The evaluation results were all based on the average values ​​measured for three samples. [Collectivity] The ability of nonwoven fabric to capture foreign matter (dust, sesame seeds, etc.) when used as a cleaning cloth was evaluated as follows.

[0182] <Dust collection ability> First, prepare a white acrylic sheet (55 cm high, 65 cm wide), and define a rectangular area of ​​5 cm high x 15 cm wide approximately in the center of the sheet as the dust dispersion area. Next, 0.20 g of each of the seven test powders conforming to JIS Z 8901 is taken. The taken test powders are then dispersed and sprinkled evenly over the dust dispersion area of ​​the white acrylic plate. For nonwoven fabrics whose dust collection properties are to be evaluated, a sample measuring 29 cm in length and 21 cm in width was taken, and its mass (M) was measured. D0 The mass of the nonwoven fabric was measured. Then, the test powder on the dust dispersion area was wiped off using the nonwoven fabric whose mass had been measured. The test powder was wiped using a commercially available floor wiper jig (Kao Corporation, product name: Quickle Wiper®, using the head of the jig body) with a surface area of ​​26 cm vertically and 16 cm horizontally that contributed to the wiping, and the top surface of the nonwoven fabric (the surface to which the water stream was last sprayed during the water entanglement process) as the wiping surface. The wiping was performed with a load of 400 gf. The wiper was moved back and forth once on the surface of the white acrylic plate. The wiping action was as follows: Position the wiper in the center of the dust dispersion area so that the vertical direction of the wiper aligns with the vertical direction of the dust dispersion area. From there, move the wiper 250mm towards the left edge of the dust dispersion area, rubbing it against the dust (white acrylic plate). Then, move the wiper 500mm toward the right edge of the dust dispersion area, Furthermore, the wiper was moved 250 mm toward the left edge of the dust dispersion area and the wiper was swung back and forth once. After wiping back and forth once with the wiper, the mass of the nonwoven fabric used for wiping (M D ) Measure the mass (M) of the nonwoven fabric before and after wiping. D0 M D The dust collection efficiency (%) was calculated using the following formula based on the mass (0.2g) of the test powder scattered on the white acrylic plate. • Dust collection efficiency (%) = 100 × (M D-M D0 ) / 0.2 For evaluating the dust collection performance of nonwoven fabrics, the wiping test was performed three times using a new wiping surface of the nonwoven fabric, washing a white acrylic plate with tap water, and allowing it to dry. The average of the obtained measurements was used to determine the dust collection efficiency of the nonwoven fabric.

[0183] <Hair capture ability (wet state)> To evaluate the performance of nonwoven fabric when used as a wiping sheet, the hair collection ability was evaluated using the following method. First, place five strands of hair (approximately 5 cm long) on ​​a commercially available flooring board (three 14 cm long and 90 cm wide flooring boards joined together to create a board that is 42 cm long and 90 cm wide), three horizontally and two vertically, with a 2 cm gap between them. Next, to evaluate the hair-catching ability of the nonwoven fabric in a wet state, three samples measuring 29 cm in length and 21 cm in width were taken, and hair was wiped using the collected nonwoven fabric pieces. The wiping is performed in a wet state by impregnating 100 parts by mass of nonwoven fabric with 250 parts by mass of distilled water. The hair that has fallen onto the flooring is wiped away using the following procedure. First, the area contributing to the wiping was set to 26 cm in the vertical direction and 16 cm in the horizontal direction, and the top surface of the nonwoven fabric (the surface where the water stream was last sprayed during the water entanglement process) became the wiping surface. The nonwoven fabric, which had been moistened using the method described above, was attached to a commercially available floor wiper jig (manufactured by Kao Corporation, product name: Quickle Wiper®, using the head part of the jig body), and the process was carried out under a load of 400 gf. The wiping was performed using the same method as the one used in the evaluation of dust collection performance, by moving the wiper back and forth once over the flooring where the hair had fallen. After wiping, the collection rate (%) was calculated from the number of hairs wiped off the flooring. For evaluating the hair-catching ability (wet state) of nonwoven fabrics, the wiping test was performed by first using a new wiping surface of the nonwoven fabric, thoroughly wiping the flooring board, and then repeating the same wiping test three times. The average of the obtained measurements was taken as the hair-catching rate (wet state) of the evaluated nonwoven fabric.

[0184] <Sesame seed gathering ability (wet state)> To evaluate the performance of nonwoven fabric when used as a wiping sheet, the sesame seed collection ability was evaluated using the following method. First, place 10 sesame seeds in three rows on a commercially available flooring board (three 14cm x 90cm flooring boards joined together to create a 42cm x 90cm flooring board). (The rows should consist of 3, 4, and 3 sesame seeds, with a 2cm gap between each row.) Next, to evaluate the sesame seed collection ability in a wet state, three samples of nonwoven fabric measuring 29 cm in length and 21 cm in width were taken, and sesame seeds were wiped off using the collected nonwoven fabric pieces. The wiping is performed in a wet state by impregnating 100 parts by mass of nonwoven fabric with 250 parts by mass of distilled water. The sesame seeds that have fallen onto the flooring can be wiped up using the following procedure. First, the area contributing to the wiping was set to 26 cm in the vertical direction and 16 cm in the horizontal direction. The top surface of the nonwoven fabric (the surface where the water stream was last sprayed during the water entanglement process) was used as the wiping surface. The nonwoven fabric, moistened using the method described above, was attached to a commercially available floor wiper jig (manufactured by Kao Corporation, product name: Quickle Wiper®, using the head of the jig body) and a load of 400 gf was applied. Wiping was performed using the same method as used in the dust collection performance evaluation, by moving the wiper back and forth once over the floor where the sesame seeds had been dropped. After wiping, the collection rate (%) was calculated from the number of sesame seeds wiped off the flooring. For evaluating the sesame seed collection ability (wet state) of nonwoven fabrics, the wiping test was performed by first using a new wiping surface of the nonwoven fabric, thoroughly wiping the flooring board, and then repeating the same wiping test three times. The average of the obtained measurements was taken as the sesame seed collection rate (wet state) of the evaluated nonwoven fabric.

[0185] <Average coefficient of friction and coefficient of variation: KES> The average coefficient of friction (MIU) and its variation (MMD) were measured using a friction tester (KES-SE, Kato Tech Co., Ltd.). A 5cm x 10cm nonwoven fabric sample was prepared. Samples were prepared with the MD direction as the longer side and the CD direction as the longer side. A piano wire sensor (manufactured by Kato Tech Co., Ltd.) was used as the contact terminal of the measuring instrument. The test piece was fixed to the measuring stand, and the contact terminal (25g) was moved at a speed of 1.0mm / sec along a distance of 30mm on the surface of the fiber layer X1 of the test piece. The MMD was evaluated between a point 5mm from the starting point and a point 25mm from the starting point. Three measurements were taken for the test piece with the MD direction as the longer side, and three measurements were taken for the test piece with the CD direction as the longer side. The average of the three measurements was taken as the MMD for each direction. Furthermore, the average of the total six measurements was calculated.

[0186] MIU and MMD in a wet state were measured with 100 parts by mass of nonwoven fabric impregnated with 250 parts by mass of distilled water.

[0187] For the nonwoven fabric of Example 7, the mean kinetic friction coefficient and coefficient of variation were measured for the first and second entangled sections, respectively.

[0188] <Static friction coefficient, kinetic friction coefficient> The static friction coefficient μs and the dynamic friction coefficient μk were measured using a static / dynamic friction measuring instrument (Tribomast TL201Ts, manufactured by Trinity Labs Co., Ltd.). A 5cm x 10cm nonwoven fabric sample was prepared. A total of six sample pieces were prepared: three with the MD direction as the longer side and three with the CD direction as the longer side.

[0189] A flat contact element (manufactured by Trinity Lab Co., Ltd.) was used as the contact terminal of the measuring instrument. A sample piece was impregnated with 250 parts by mass of distilled water at a rate of 100 parts by mass. The sample piece was then attached to the flat contact element, and the measuring table of the measuring instrument (table sliding type) to which the flat contact element was attached was positioned so that it was in contact with the test piece under a load of 100 gf (contact area 5.0 cm × 6.5 cm). The measuring table was moved back and forth twice at a speed of 10 mm / sec over a distance of 30 mm for evaluation. The value (kinetic friction force) from the second back-and-forth movement was read, and the average of the forward and return values ​​was taken as the kinetic friction force (gf) of one sample piece. Furthermore, the average of the value at the start of the forward movement and the value at the start of the return movement of the second back-and-forth movement was taken as the static friction force (gf) of one sample piece. Measurements were performed on six test pieces, and the average of the six measured values ​​was taken as the static friction force Fs(gf) and kinetic friction force Fk(gf) for each example and comparative example.

[0190] The static friction coefficient μs and kinetic friction coefficient μk of the short fiber layer side surface were calculated from the static friction force Fs(gf), kinetic friction force Fk(gf), and load (100gf).

[0191] For the nonwoven fabric of Example 7, the static friction coefficient and the dynamic friction coefficient were measured for the first entanglement portion and the second entanglement portion, respectively.

[0192] [Table 1]

[0193] [Table 2]

[0194] [Table 3]

[0195] [Table 4]

[0196] [Table 5]

[0197] [Table 6]

[0198] Of Examples 1-4, Examples 1 and 2 showed slightly inferior hair collection performance compared to Comparative Example 1, which had a fiber layer X1 composed solely of irregularly shaped cross-section fibers. However, their collection performance in other areas was equivalent to or better than Comparative Example 1. Furthermore, Examples 1-4 exhibited a higher modulus at 10% elongation and a smaller wet MMD measured by the KES method compared to Comparative Example 1. This is thought to be due to the formation of dense entanglement in the nonwoven fabric by the fibers A1-A3 (fibers 1-3 derived from split-type composite fibers) contained in Examples 1-4. The MMD measured by the KES method is an indicator of the smoothness of the nonwoven fabric surface. A smaller MMD indicates that, when used for wiping, the nonwoven fabric will make uniform contact with the surface being wiped, resulting in less uneven wiping.

[0199] Examples 1-4 all exhibited superior collection performance compared to Comparative Example 2, which did not contain fibers A1-A3 in the fiber layer X1. This is thought to be because the low-fiber fibers A1-A3 in these examples exhibited excellent collection performance. Furthermore, Examples 1-4 showed a higher modulus at 10% elongation and a lower wet MMD measured by the KES method compared to Comparative Example 2. This is thought to be because the fibers A1-A3 (fibers 1-3 derived from split-type composite fibers) contained in Examples 1-4 formed a dense entanglement in the nonwoven fabric.

[0200] Comparative Example 3 was inferior in hair collection property and dust collection property to Examples 1 to 4. This is presumably because in Comparative Example 3, the fiber layer X1 was composed only of fibers (fibers 1 to 3 or fibers A1 to A3) derived from split conjugate fibers, and the nonwoven fabric surface was dense, resulting in clogging on the nonwoven fabric surface during wiping. Comparative Example 3 also had a static friction coefficient μs and a kinetic friction coefficient μk both larger than those of Examples 1 to 4 when wet. This is also presumably because the surface of Comparative Example 3 was composed only of fibers with a small fineness and was dense, increasing the adhesion to the target surface. The static friction coefficient μs and the kinetic friction coefficient μk serve as indicators of the wiping resistance when used for wiping applications. The smaller these values are, the less wiping resistance there is when the nonwoven fabric moves on the wiping target surface, making it easier to wipe with a light force. Also, it is less likely to damage the wiping target surface.

[0201] Example 5 was superior in collection property compared to Comparative Example 2 that did not contain fibers A1 to A3 in the fiber layer X. Also, compared to Examples 1 and 2 where the fibers contained in the nonwoven fabric were the same, as the mixing ratio of the profiled cross-section fibers increased, the stress at 10% elongation in the CD direction increased. This is presumably due to the framework role of the profiled cross-section fibers.

[0202] Example 6 was superior in collection property compared to all Examples and Comparative Examples. On the other hand, it had the lowest stress at 10% elongation in the CD direction and the lowest tensile strength in the CD direction among the Examples, and as a result, it was a nonwoven fabric that was easily stretchable in the CD direction and difficult to handle depending on the usage method. This is presumably because the profiled cross-section fibers with a large fineness formed many inter-fiber voids in the nonwoven fabric and were able to collect dirt, but the entanglement between the fibers also decreased.

[0203] Example 7 was superior in collection performance as compared with Example 2 in which the fibers contained in the nonwoven fabric were the same and had a similar ratio. Example 7 also showed lower values for both the static friction coefficient μs and the kinetic friction coefficient μk when wet, as compared with Example 2, in the portion where the pattern was arranged. These are presumably because appropriate voids were formed on the nonwoven fabric surface by pattern formation, and the adhesion to the target surface was reduced, resulting in excellent wiping ease. Also, the tensile strength in the CD direction was high as compared with all the examples and comparative examples, and the result was that the handling property was good even when the usage method was changed. This is presumably because the number of jetting times of the columnar water flow for forming the pattern was one more than that in the other examples and comparative examples, and the entanglement of the fibers advanced due to the formation of the pattern portion.

[0204] In Comparative Example 4, all the collection performances were inferior to those of all the examples. This is presumably because in Comparative Example 4, the fiber layer X1 was composed only of fibers (fibers 1 to 3 or fibers A1 to A3) derived from the split-type composite fiber, and the nonwoven fabric surface was dense, resulting in clogging on the nonwoven fabric surface during wiping. Comparative Example 4 also had both a static friction coefficient μs and a kinetic friction coefficient μk when wet that were larger than those of all the examples. This is also presumably because the surface of Comparative Example 4 was composed only of fibers with a small fineness and was dense, increasing the adhesion to the target surface.

[0205] Furthermore, an electron microscope (SEM) photograph of the surface of the second entanglement portion of the nonwoven fabric obtained in Example 7 is shown as FIG. 3. Figure 3 shows that relatively large voids are formed around the irregularly shaped cross-section fibers, and that the ultrafine fibers formed by the division of the segmented composite fibers exist in bundles, with small voids formed between the ultrafine fibers, resulting in the formation of various types of voids. These bundled ultrafine fibers have a relatively high degree of freedom and are easily moved by external forces, so it is thought that they play a role in improving the wiping properties of the nonwoven fabric. Furthermore, the striated voids between the ultrafine fibers of the bundled ultrafine fiber groups (shown by solid arrows in Figure 3) have a similar structure to the striated recesses formed between the convex parts of the irregularly shaped cross-section fibers (shown by dotted arrows in Figure 3). In other words, when the ultrafine fiber group is considered as a single fiber, its lateral shape is similar to that of the irregularly shaped cross-section fiber. This similarity is presumed to be what makes the nonwoven fabric's functions (e.g., wiping properties, tactile feel, etc.) unique, stemming from the shapes of both the ultrafine fiber group and the irregularly shaped cross-section fiber.

[0206] The nonwoven fabric of this embodiment includes the following aspects. (Aspect 1) A nonwoven fabric comprising a fiber layer X1 containing 10% to 90% by mass of fibers derived from irregularly shaped cross-section fibers having at least multiple protrusions in their cross-sectional surface, and 10% to 90% by mass of fibers A made of thermoplastic resin (excluding the aforementioned irregularly shaped cross-section fibers), The fiber A comprises a plurality of fibers with different fiber cross-sectional shapes and areas. When the total number of fibers A in the fiber layer X1, as measured by the following method, is taken as 100%, the fiber layer X1 contains the following fibers A1 to A3 as fiber A, in the following proportions: Nonwoven fabrics are fabrics in which fibers are intertwined and fused together. (i) Fiber A1 having a fiber cross-sectional area less than 0.25 times the maximum fiber cross-sectional area Smax of fiber A: 20% to 85%. (ii) Fiber A2 having a fiber cross-sectional area of ​​0.25 times or more and 0.5 times or less than the maximum fiber cross-sectional area Smax of fiber A: 5% to 60%. (iii) Fiber A3 having a fiber cross-sectional area greater than 0.5 times and less than or equal to 1 time the maximum fiber cross-sectional area Smax of fiber A: 10% to 70%. [Method for measuring the number of fibers A in fiber layer X1] (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) From the captured image, count the number of fibers A and measure the fiber cross-sectional area using the image analysis software "Micro Measure". (Aspect 2) The maximum fiber cross-sectional area Smax in fiber A is 150 μm². 2 Over 1300 μm 2 The nonwoven fabric is as follows, according to Embodiment 1. (Aspect 3) The fiber layer X1 comprises 10% to 90% by mass of fibers derived from irregularly shaped cross-section fibers having at least multiple protrusions in their cross-section, and 10% to 90% by mass of fibers derived from segmented composite fibers. The fibers derived from the aforementioned split-type composite fibers include partially split fibers. Nonwoven fabrics are fabrics in which fibers are intertwined and fused together. (Aspect 4) The nonwoven fabric according to claim 3, wherein, when the total number of fibers derived from the split composite fiber measured by the following method is taken as 100%, it satisfies at least one selected from the group consisting of (i) to (iii) below. (i) The proportion of fiber 1 (a fiber having a cross-sectional area less than 0.25 times the cross-sectional area of ​​an undivided split composite fiber) is 20% or more and 85% or less. (ii) The proportion of fiber 2 (fibers having a cross-sectional area of ​​0.25 times or more and 0.5 times or less than the cross-sectional area of ​​the undivided divided composite fiber) is 5% or more and 60% or less. (iii) The proportion of fiber 3 (fibers having a cross-sectional area greater than 0.5 times the cross-sectional area of ​​undivided divided composite fibers) is between 10% and 70%. [Method for measuring the number of fibers and fiber cross-sectional area derived from split-type composite fibers] (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) The number of fibers derived from the segmented composite fiber is counted from the captured image, and the cross-sectional area of ​​the fiber is measured using the image analysis software "Micro Measure". (Aspect 5) The fiber cross-sectional area of ​​the fiber 1 is 3 μm². 2 More than 116μm 2 The following: The fiber cross-sectional area of ​​fiber 2 is 116 μm². 2 Over 150 μm 2 The following: The fiber cross-sectional area of ​​the fiber 3 is 150 μm². 2 Over 1300 μm 2 The nonwoven fabric according to claim 4. (Aspect 6) The nonwoven fabric is any of embodiments 1 to 5, wherein the first entangled portion and the second entangled portion are arranged in a striped pattern. (Aspect 7) The nonwoven fabric of embodiment 6, wherein the first entanglement portion and the second entanglement portion are meandering. (Pattern 8) A nonwoven fabric in any of embodiments 1 to 7, further comprising a fiber layer Y different from the fiber layer X1, wherein the fiber layer Y is located between the two fiber layers X1. (Aspect 9) In the aforementioned irregularly shaped cross-section fiber, at least one convex portion has a substantially curved tip, and the width Wb of the root portion toward the center of the fiber is smaller than the maximum width Wt of the tip portion, in any of embodiments 1 to 8 of the nonwoven fabric. (Aspect 10) The nonwoven fabric of embodiment 8, wherein the fiber layer Y contains 10% to 100% by mass of short fibers with a fiber length of 200 mm or less. (Aspect 11) The nonwoven fabric of embodiment 8, wherein the fiber layer Y contains 10% to 100% by mass of hydrophilic fibers with a fiber length of 20 mm to 100 mm. (Aspect 12) The nonwoven fabric according to embodiment 11, wherein the hydrophilic fibers are cellulose fibers. (Aspect 13) The nonwoven fabric according to any one of claims 1 to 12, wherein the irregularly shaped cross-section fibers have 3 to 8 protrusions in the fiber cross-section. (Aspect 14) The fibers derived from the profiled cross-section fibers include fibers formed by splitting or peeling at least one of the plurality of convex portions of the profiled cross-section fibers, and the non-woven fabric according to any one of Aspects 1 to 13. (Aspect 15) The maximum width Wt of the convex portion is 3.5 μm or more and 20 μm or less, and the length Lt is 4 μm or more and 25 μm or less, and the non-woven fabric according to any one of Aspects 1 to 14. (Aspect 16) In the fiber cross-section of the profiled cross-section fiber, the convex portion has a constricted portion toward the center of the fiber, and the width Wb of the root portion of the convex portion is smaller than the maximum width Wt of the convex portion. The width Wb of the root portion of the convex portion is 2 μm or more and 12 μm or less. The ratio Lt / Wb of the length Lt of the convex portion to the width Wb of the root portion is 1.0 or more and 3.5 or less, and Wt / Wb of the maximum width Wt to the width Wb of the root portion is greater than 1 and 3.5 or less, and the non-woven fabric according to any one of Aspects 1 to 15. (Aspect 17) The tensile strength in the MD direction in the dry state is 20.0 N / 5 cm or more and 400.0 N / 5 cm or less and / or the 10% modulus in the MD direction is 1.0 N / 5 cm or more and 20.0 N / 5 cm or less. The non-woven fabric of Aspect 12. (Aspect 18) The non-woven fabric for a wiping cloth base material, which is the non-woven fabric according to any one of Aspects 1 to 17. (Aspect 19) Using the non-woven fabric of Aspect 11 and any one of Aspects 12 to 18 that cite Aspect 11 as a base material, and impregnating the base material with a liquid in a proportion within the range of 100 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the base material. (Aspect 20) Producing a fiber web containing 10% by mass or more and 90% by mass or less of profiled cross-section fibers having a plurality of convex portions in the fiber cross-section and 10% by mass or more and 90% by mass or less of split-type composite fibers. Subjecting the fiber web to entanglement treatment using a high-pressure fluid flow of 1 MPa or more and 10 MPa or less to entangle the fibers with each other, and a method for producing a non-woven fabric. (Aspect 21) The entanglement process is carried out by injecting a high-pressure fluid stream into the fiber web such that areas where a high-pressure fluid stream is injected from two or more consecutive orifices of a nozzle and areas where a high-pressure fluid stream is not injected into the fiber web are alternately located. Method for manufacturing nonwoven fabric according to embodiment 20. (Aspect 22) The aforementioned entanglement process is carried out by placing a member between the fiber web and a nozzle, which has multiple holes arranged in a line perpendicular to the direction of propagation of the fiber web and which prevents the high-pressure fluid from passing through areas other than the holes, and by injecting a high-pressure fluid stream from the nozzle. Method for manufacturing nonwoven fabric according to embodiment 20. [Industrial applicability]

[0207] The nonwoven fabric of the present disclosure comprises a fiber layer composed of irregularly shaped cross-sectional fibers and / or fibers derived therefrom, and three types of fibers having a specific fiber cross-sectional area, or a segmented composite fiber and fibers derived therefrom. When used as a wiping cloth, these fibers effectively remove dirt and allow for wiping / polishing with light force. Furthermore, by combining the fiber layer X1 with an appropriate fiber layer Y, it is possible, for example, to provide the wiping cloth in a wet state or to adjust the stiffness of the wiping cloth. Therefore, the nonwoven fabric of the present disclosure is suitable for household and industrial wiping cloths used for wiping away dirt from the surface of various objects and / or applying finishing agents.

Claims

1. A nonwoven fabric comprising a fiber layer X1 containing 10% by mass or more and 90% by mass or less of fibers derived from irregularly shaped cross-section fibers having at least multiple protrusions in their cross-sectional surface, and 10% by mass or more and 90% by mass or less of fibers A made of thermoplastic resin (excluding the aforementioned irregularly shaped cross-section fibers), The fiber A includes a plurality of fibers with different fiber cross-sectional shapes and areas. When the total number of fibers A in the fiber layer X1 measured by the following method is taken as 100%, the fiber layer X1 contains the following fibers A1 to A3 as fibers A, in the following proportions: Nonwoven fabric is a material in which fibers are intertwined and fused together. (i) Fibers A1 having a fiber cross-sectional area less than 0.25 times the maximum fiber cross-sectional area Smax of fiber A: 20% to 85%. (ii) Fiber A2 having a fiber cross-sectional area of ​​0.25 times or more and 0.5 times or less than the maximum fiber cross-sectional area Smax of fiber A: 5% to 60%. (iii) Fiber A3 having a fiber cross-sectional area greater than 0.5 times and less than or equal to 1 time the maximum fiber cross-sectional area Smax of fiber A: 10% to 70%. [Method for measuring the number of fibers A in fiber layer X1] (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) The number of fibers A is counted from the captured image, and the fiber cross-sectional area is measured using the image analysis software "MicroMeasure".

2. The maximum fiber cross-sectional area Smax in fiber A is 150 μm. ２ Over 1300 μm ２ The nonwoven fabric according to claim 1, which is as follows:

3. The fiber layer X1 comprises 10% to 90% by mass of fibers derived from irregularly shaped cross-section fibers having at least multiple protrusions in their cross-sectional surface, and 10% to 90% by mass of fibers derived from segmented composite fibers. The fibers derived from the aforementioned split-type composite fibers include partially split fibers. Nonwoven fabrics are fabrics in which fibers are intertwined and fused together.

4. The nonwoven fabric according to claim 3, wherein, when the total number of fibers derived from the split composite fiber measured by the following method is taken as 100%, it satisfies at least one selected from the group consisting of (i) to (iii) below. (i) The proportion of fiber 1 (a fiber having a cross-sectional area less than 0.25 times the cross-sectional area of ​​an undivided segmented composite fiber) is 20% or more and 85% or less. (ii) The proportion of fiber 2 (fibers having a cross-sectional area of ​​0.25 times or more and 0.5 times or less than the cross-sectional area of ​​the undivided divided composite fiber) is 5% or more and 60% or less. (iii) The proportion of fiber 3 (fibers having a cross-sectional area greater than 0.5 times the cross-sectional area of ​​undivided divided composite fibers) is between 10% and 70%. [Method for measuring the number of fibers and fiber cross-sectional area derived from split-type composite fibers] (1) Observe and photograph a cross-section of the nonwoven fabric at 150x magnification using an electron microscope. (2) The number of fibers derived from the segmented composite fiber is counted from the captured image, and the cross-sectional area of ​​the fiber is measured using the image analysis software "MicroMeasure".

5. The fiber cross-sectional area of ​​the fiber 1 is 3 μm². ２ 116 μm or more ２ The following: The cross-sectional area of ​​the fiber 2 is 116 μm². ２ Over 150 μm ２ The following: The cross-sectional area of ​​the fiber 3 is 150 μm². ２ Over 1300 μm ２ The nonwoven fabric according to claim 4.

6. The nonwoven fabric according to claim 1 or 3, wherein the first entangled portion and the second entangled portion are arranged in a striped pattern.

7. The nonwoven fabric according to claim 6, wherein the first entanglement portion and the second entanglement portion are meandering.

8. The nonwoven fabric according to claim 1 or 3, further comprising a fiber layer Y different from the fiber layer X1, wherein the fiber layer Y is located between the two fiber layers X1.

9. The nonwoven fabric according to claim 1 or 3, wherein in the irregularly shaped cross-section fiber, at least one convex portion has a substantially curved tip, and the width Wb of the root portion toward the center of the fiber is smaller than the maximum width Wt of the tip portion.

10. The nonwoven fabric according to claim 8, wherein the fiber layer Y contains 10% by mass or more and 100% by mass or less of short fibers with a fiber length of 200 mm or less.

11. The nonwoven fabric according to claim 8, wherein the fiber layer Y contains 10% by mass to 100% by mass of hydrophilic fibers with a fiber length of 20 mm to 100 mm.

12. The nonwoven fabric according to claim 11, wherein the hydrophilic fibers are cellulose fibers.

13. The nonwoven fabric according to claim 1 or 3, wherein the irregularly shaped cross-section fiber has 3 to 8 protrusions in the fiber cross-section.

14. The nonwoven fabric according to claim 1 or 3, wherein the fibers derived from the irregularly shaped cross-section fibers include fibers formed by dividing or peeling off at least one of the multiple protrusions of the irregularly shaped cross-section fibers.

15. The nonwoven fabric according to claim 1 or 3, wherein the maximum width Wt of the protrusion is 3.5 μm or more and 20 μm or less, and the length Lt is 4 μm or more and 25 μm or less.

16. In the fiber cross-section of the irregularly shaped fiber, the convex portion has a portion that is constricted toward the center of the fiber, and the width Wb of the base portion of the convex portion is smaller than the maximum width Wt of the convex portion. The width Wb of the base portion of the aforementioned protrusion is 2 μm or more and 12 μm or less. The nonwoven fabric according to claim 1 or 3, wherein the ratio Lt / Wb of the length Lt of the protrusion to the width Wb of the base portion is 1.0 or more and 3.5 or less, and the ratio Wt / Wb of the maximum width Wt to ​​the width Wb of the base portion is greater than 1 and 3.5 or less.

17. The tensile strength in the MD direction in the dry state is 20.0 N / 5 cm or more and 400.0 N / 5 cm or less and / or the 10% modulus in the MD direction is 1.0 N / 5 cm or more and 20.0 N / 5 cm or less. The nonwoven fabric according to claim 12.

18. A nonwoven fabric for a wiping cloth base, which is a nonwoven fabric according to claim 1 or 3.

19. A liquid-impregnated wiping cloth, wherein the nonwoven fabric described in claim 11 is used as the base material, and the liquid is impregnated in a ratio of 100 parts by mass or more and 1000 parts by mass or less per 100 parts by mass of the base material.

20. To produce a fiber web containing 10% to 90% by mass of irregularly shaped cross-section fibers having multiple protrusions in their cross-section, and 10% to 90% by mass of segmented composite fibers. A method for producing a nonwoven fabric, comprising subjecting the fiber web to an entanglement treatment using a high-pressure fluid flow of 1 MPa to 10 MPa to cause the fibers to become entangled with each other.

21. The entanglement process is carried out by injecting a high-pressure fluid stream into the fiber web such that areas where a high-pressure fluid stream is injected from two or more consecutive orifices of a nozzle and areas where a high-pressure fluid stream is not injected into the fiber web are alternately located. A method for producing a nonwoven fabric according to claim 20.

22. The aforementioned entanglement process is carried out by placing a member between the fiber web and a nozzle, which has multiple holes arranged in a line perpendicular to the direction of propagation of the fiber web and which prevents the high-pressure fluid from passing through areas other than the holes, and by injecting a high-pressure fluid stream from the nozzle. A method for producing a nonwoven fabric according to claim 20.

Images