Nonwoven fabric and method for manufacturing the same

Abstract

To provide a nonwoven fabric containing cellulosic fibers, which achieves softness of nonwoven fabric feeling and suppresses fluff and can be used for a product to directly come in contact with human skin, such as an absorbent article, and a manufacturing method of the nonwoven fabric.SOLUTION: A nonwoven fabric contains cellulosic fibers and adhesive fibers, includes bonded parts between the adhesive fiber and the cellulosic fiber and / or the adhesive fiber, and includes entangled parts between the cellulosic fiber and the cellulosic fiber and / or the adhesive fiber. Bonding intersection index A of the nonwoven fabric is 1 to 60 points / mm2 or thickness reduction rate of the nonwoven fabric is 30 to 45%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a nonwoven fabric and a method for manufacturing the nonwoven fabric.

Background Art

[0002] Nonwoven fabrics are used, for example, in absorbent articles such as disposable diapers, sanitary napkins, incontinence pads, and pantiliners. Since cellulose-based fibers are excellent in hygroscopicity and are renewable fibers derived from plants, nonwoven fabrics containing cellulose-based fibers are of interest from the viewpoint of reducing the natural environmental load. Nonwoven fabrics containing cellulose-based fibers are insufficient in suppressing fuzz, and thus, for example, nonwoven fabrics subjected to water entanglement and nonwoven fabrics in which constituent fibers are adhered to each other by heat fusion of heat-fusible fibers are used. However, the former has a stiff texture, and the latter still has a problem that fuzz suppression is not sufficient. Therefore, nonwoven fabrics containing cellulose-based fibers are not used for applications that directly touch human skin, but are used for absorbers such as absorbent articles that do not directly touch human skin and for which suppression of fuzz and softness of texture are not important (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a nonwoven fabric containing cellulose-based fibers that achieves both softness of texture and suppression of fuzz and can be used for applications that directly touch human skin, such as absorbent articles, and a method for manufacturing the nonwoven fabric.

Means for Solving the Problems

[0005] The inventors of the present invention have found that for a nonwoven fabric containing both cellulosic fibers and adhesive fibers, by including the locations where the fibers are adhered by the adhesive fibers and the locations where the fibers are entangled, and further adjusting specific physical properties of the nonwoven fabric, it is possible to improve at least one of the suppression of fiber fuzz and the softness of the texture, and preferably both, thus completing the present invention. Furthermore, the inventors of the present invention have found that when manufacturing a nonwoven fabric containing both cellulosic fibers and adhesive fibers, by adhering the fibers to each other in advance and then entangling the fibers, a nonwoven fabric can be obtained that achieves both softness of texture and suppression of fiber fuzz, thus completing the present invention.

[0006] That is, in one aspect of the present invention, a nonwoven fabric containing cellulosic fibers and adhesive fibers, including the adhesion sites between the adhesive fibers and the cellulosic fibers and / or the adhesive fibers, including the entanglement sites between the cellulosic fibers and the cellulosic fibers and / or the adhesive fibers, wherein the adhesion intersection index A of the nonwoven fabric is 1 to 60 per mm 2 or the thickness reduction rate of the nonwoven fabric is 30 to 45%, and provides a nonwoven fabric. The nonwoven fabric of the embodiment of the present invention can be used, for example, in applications that directly contact human skin such as absorbent articles.

[0007] Also, in another aspect of the present invention, a method for manufacturing a nonwoven fabric containing cellulosic fibers and adhesive fibers, including an adhesion step of adhering the fibers to each other with the adhesive fibers and an entanglement step of entangling the fibers after the adhesion step, provides a method for manufacturing a nonwoven fabric.

Advantages of the Invention

[0008] Since the nonwoven fabric of the present disclosure has the above-described characteristics, it has both suppression of fiber fuzz and softness of texture, and can be used, for example, in applications that directly contact human skin such as absorbent articles.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0010] The nonwoven fabric of the embodiment of the present invention is a nonwoven fabric containing cellulose fibers and adhesive fibers, including adhesion points between the adhesive fibers and the cellulose fibers and / or the adhesive fibers, including entanglement points between the cellulose fibers and the cellulose fibers and / or the adhesive fibers, (i) the adhesion intersection index A of the nonwoven fabric is 1 to 60 pieces / mm 2 or (ii) the thickness reduction rate of the nonwoven fabric is 30 to 45%, a nonwoven fabric. The nonwoven fabric of the embodiment of the present invention can be used for applications of skin contact products that directly touch the human skin such as absorbent articles (for example, topsheets and backsheets for absorbent articles, liquid-impregnated skin covering materials impregnated with liquids such as cosmetics (for example, face masks, cutin care sheets, and décolleté sheets, etc.), base fabrics for various poultice materials including warm compresses and cold compresses, wiping materials for humans (for example, cleansing sheets, antiperspirant sheets, and antibacterial sheets, etc.), etc.).

[0011] (Cellulose fibers) In the nonwoven fabric of the embodiment of the present invention, the "cellulosic fiber" is also called a cellulose fiber and generally refers to a fiber made of cellulose as a raw material. Cellulosic fibers include, for example, natural fibers derived from plants such as cotton, hemp, linen, ramie, jute, banana, bamboo, kenaf, shell ginger, hemp, and kapok; regenerated fibers such as rayon and polynosic rayon obtained by the viscose method, cupra obtained by the copper ammonia method, and Tencel (registered trademark) and Lyocell (registered trademark) obtained by the solvent spinning method; cellulose fibers obtained by the melt spinning method; and semi-synthetic fibers such as acetate fibers. There is no particular limitation as long as the nonwoven fabric of the present invention can be obtained.

[0012] The fineness of the cellulosic fiber is preferably 0.6 to 5.6 dtex, more preferably 1.0 to 4.4 dtex, and even more preferably 1.4 to 3.3 dtex. When the fineness of the cellulosic fiber is within the above range, it is preferable because the strength of the nonwoven fabric is more suitable since the fineness is not too small, and the texture of the nonwoven fabric is more suitable since the fineness is not too large. Also, when the fineness of the cellulosic fiber is within the above range, the entanglement property of the fiber is more suitable, and since the entanglement property of the nonwoven fabric is not too low, the strength and hairiness of the nonwoven fabric are more suitable, and since the entanglement property of the nonwoven fabric is not too high, the texture of the nonwoven fabric is more suitable, so it is preferable.

[0013] The fiber diameter of the cellulosic fiber is preferably 5 to 25 μm, more preferably 8 to 20 μm, and even more preferably 10 to 17 μm. When the fiber diameter of the cellulosic fiber is within the above range, it is preferable because the strength of the nonwoven fabric is more suitable since the fineness is not too small, and the texture of the nonwoven fabric is more suitable since the fineness is not too large. Also, when the fineness of the cellulosic fiber is within the above range, the entanglement property of the fiber is more suitable, and since the entanglement property of the nonwoven fabric is not too low, the strength and hairiness of the nonwoven fabric are more suitable, and since the entanglement property of the nonwoven fabric is not too high, the texture of the nonwoven fabric is more suitable, so it is preferable.

[0014] The fiber length of the cellulose fiber is preferably 25 to 100 mm, more preferably 30 to 70 mm, and even more preferably 35 to 60 mm. When the fiber length of the cellulose fiber is within the above range, the entanglement of the fibers is suitable, so it is preferable. In particular, the non-woven fabric of the present disclosure can be manufactured by once adhering the constituent fibers with an adhesive fiber and then performing an entanglement treatment. Therefore, since the fiber length is not too large, the number of adhesion points in one fiber becomes more appropriate, and the fibers can be more suitably entangled to sufficiently suppress the fluff, which is preferable. Also, since the fiber length is not too small, the number of adhesion points in one fiber becomes more appropriate, and the fibers can be more suitably entangled to sufficiently soften the texture of the non-woven fabric, which is preferable.

[0015] The cross-section of the cellulose fiber (cross-sectional surface, or cross-section perpendicular to the fiber length direction) may be circular or non-circular. Examples of non-circular shapes include elliptical, Y-shaped, X-shaped, well-shaped, multi-leaf-shaped, polygonal, star-shaped, chrysanthemum-shaped, etc. When the cross-section of the fiber is circular, the area of adhesion to the adhesive fiber is relatively small, so the softness of the texture of the non-woven fabric can be better. When the cross-section of the fiber is non-circular, the area of adhesion to the adhesive fiber is relatively large, so the fluffing of the non-woven fabric can be better suppressed, or the strength of the non-woven fabric can be higher.

[0016] The cellulose fiber is preferably a chemical fiber such as a regenerated fiber or a semi-synthetic fiber. Chemical fibers are more preferable because they can further reduce the variation in fineness and / or fiber diameter and fiber length, and it is easier to adjust the degree of entanglement of the non-woven fabric. Also, rayon and solvent-spun cellulose fibers, etc., have a good balance of softness and strength when wet, and it is easier to obtain a suitable softness and strength of the texture as a non-woven fabric, which is preferable. Also, solvent-spun cellulose fibers are preferable in that they can better suppress the fluffing of the non-woven fabric and increase the strength of the non-woven fabric because of their relatively high single fiber strength. The cellulose fibers can be used alone or in combination.

[0017] Cellulose fibers may be surface-treated to change the degree of hydrophilicity or hydrophobicity of their surfaces. Generally, an oil agent (surfactant) can be used to change the degree of hydrophilicity or hydrophobicity of the surface of cellulose fibers. The degree of hydrophilicity or hydrophobicity can be evaluated using values such as the sedimentation rate of the fibers. The surface of cellulose fibers may be hydrophilic or hydrophobic. The value of the sedimentation rate (or sedimentation time (sec)) of the fibers may be, for example, 30 seconds or less, more preferably 20 seconds or less, and even more preferably 10 seconds or less. When the sedimentation rate (or sedimentation time) of cellulose fibers is small, the entanglement property of cellulose fibers can be relatively improved, the fluffing of the nonwoven fabric can be more effectively suppressed, or the strength of the nonwoven fabric can be increased.

[0018] The sedimentation rate of the fibers can be measured by the following method. Collect 17 g of the fibers for which the sedimentation rate is to be measured. Open the collected fibers (using a parallel carding machine) to form a card web. Weigh 5 g of the card web and fill it into a cage made of copper wire (thickness 0.55 mm) (a cylindrical cage body with a diameter of 5 cm and a height of 8 cm, and the mass of the cage body is 3 g). Next, prepare a constant temperature water bath, fill it with tap water, and set the temperature to 25°C. When the water temperature reaches 25°C, stop the stirring of the constant temperature water bath and start measuring the sedimentation rate. Gently drop the cage filled with fibers in the above procedure from a position 1 cm above the water surface. When the cage touches the water surface, start the stopwatch simultaneously. As the fibers gradually absorb water, when the 8-cm-high cage completely sinks below the water surface, stop the stopwatch simultaneously. The time from when the cage touches the water surface until it sinks below the water surface is taken as the sedimentation rate, and the average value of two measurements is taken as the sedimentation rate of the fibers.

[0019] In the measurement of the above sedimentation rate, if the cage does not sink below the water surface for 5 minutes or more, it is assumed that the fiber is water-repellent. When the cellulosic fiber is water-repellent, it may be preferable in applications where the nonwoven fabric is brought into contact with a liquid. For example, in the top sheet and the second sheet for absorbent articles, since the liquid is easily transferred to the absorber without being retained too much in the sheet, it may be preferable that the cellulosic fiber is water-repellent. Further, when the nonwoven fabric has a laminated structure, by using a laminated nonwoven fabric having a layer containing a water-repellent cellulosic fiber and a layer containing a non-water-repellent cellulosic fiber, in applications such as a sheet for absorbent articles and a liquid-impregnated skin covering material impregnated with a liquid such as a cosmetic, the nonwoven fabric can preferably transfer or retain the liquid.

[0020] (Adhesive fiber) In the nonwoven fabric of the embodiment of the present invention, the "adhesive fiber" refers to a fiber that exhibits adhesiveness by an adhesion treatment (for example, heat adhesion treatment, electron beam irradiation, and ultrasonic welding (ultrasonic welder), etc.) and can adhere fibers to each other to form an adhesion site, and is not particularly limited as long as the nonwoven fabric targeted by the present disclosure can be obtained.

[0021] The adhesive fiber includes, for example, synthetic fibers made of a thermoplastic resin. The thermoplastic resin is not particularly limited as long as the nonwoven fabric targeted by the present invention can be obtained. For example, 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, propylene copolymers mainly composed of propylene (including propylene-ethylene copolymers, propylene-butene-1-ethylene copolymers), ethylene-acrylic acid copolymers, and ethylene-vinyl acetate copolymers; polyamide resins such as nylon 6, nylon 12 and nylon 66; acrylic resins; engineering plastics such as polycarbonate, polyacetal, polystyrene, cyclic polyolefin, and their elastomers, etc. can be exemplified, and these can be arbitrarily selected from them.

[0022] The adhesive component of the adhesive fiber is preferably a copolymer of an olefin and an unsaturated carboxylic acid or its derivative from the viewpoint of improving the adhesiveness to cellulose-based fibers. Examples of the unsaturated carboxylic acid include maleic acid, acrylic acid, methacrylic acid, fumaric acid, itaconic acid, etc., and examples of its derivatives include anhydrides of unsaturated carboxylic acids, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, or similar acrylic acid esters, glycidyl acrylate, glycidyl methacrylate, butene carboxylic acid esters, allyl glycidyl ether, 3,4-epoxybutene, 5,6-epoxy-1-hexene, vinylcyclohexene monooxide, etc. Particularly, it is preferable that the olefin is ethylene and the unsaturated carboxylic acid or its derivative is acrylic acid, and it is an ethylene-acrylic acid copolymer.

[0023] The synthetic fiber may be a single fiber composed of one or more thermoplastic resins selected from the above, or may be a composite fiber composed of two or more components (which may also be referred to as "sections"). In the composite fiber, each component may be composed of one thermoplastic resin, or may be a mixture of two or more thermoplastic resins. The composite fiber may be, for example, a core-sheath type composite fiber, a sea-island type composite fiber, or a side-by-side type composite fiber. The core-sheath type composite fiber may be an eccentric core-sheath type composite fiber in which the center of the core component does not coincide with the center of the sheath component in the fiber cross-section, or may be a concentric core-sheath type composite fiber in which the center of the core component coincides with the center of the sheath component in the fiber cross-section.

[0024] Regardless of whether it is a single fiber or a composite fiber, the synthetic fiber may have an irregular cross-section. In the case of a core-sheath type composite fiber and a sea-island type composite fiber, in the fiber cross-section, the core component and / or the island component may have an irregular cross-section. When the synthetic fiber has an irregular cross-section, the cross-section may be elliptical, polygonal, star-shaped, or a shape in which a plurality of convex portions are joined at the base (for example, a clover shape). In the present embodiment, two or more synthetic fibers may be used in combination as the synthetic fiber.

[0025] When the synthetic fiber is a composite fiber, two or more components may be arranged so that a thermoplastic resin having a lower melting point constitutes a part of the fiber surface. The low melting point thermoplastic resin (low melting point component) melts or softens when heat is applied in the process of producing the non-woven fabric, and becomes an adhesive component. The low melting point component contributes to the adhesion between fibers or the adhesion to other members, and can form an adhesion portion. When the synthetic fiber is a composite fiber, it is preferable that the low melting point component is exposed at a length of 50% or more, more preferably 60% or more, still more preferably 80% or more, and particularly preferably over the entire circumference of the fiber with respect to the length of the peripheral surface of the fiber in the fiber cross-section.

[0026] The nonwoven fabric of the embodiment of the present invention can be manufactured by entangling fibers with each other after previously adhering the fibers to each other. Therefore, the region where the low melting point component of the adhesive fiber is exposed on the fiber circumferential surface in the fiber cross-section is not too small, so that a more appropriate region for adhesion is present, the number of adhesion points between the fibers becomes more appropriate, the adhesive strength of the adhesion points between the fibers becomes more appropriate, and the adhesion by the adhesive fiber can be made more sufficient. Therefore, the fluff of the nonwoven fabric can be more preferably suppressed and the strength of the nonwoven fabric can be made more suitable. Furthermore, in the subsequent entanglement, the degree to which the adhesion between the fibers is eliminated becomes more appropriate, and the fluff of the nonwoven fabric and the strength of the nonwoven fabric can be made more sufficient. In particular, the nonwoven fabric of the present embodiment contains cellulosic fibers, and the adhesiveness between the cellulosic fibers and the adhesive fibers is not high, so the elimination of the adhesion points between the fibers is more promoted, and thus the fluff and strength of the nonwoven fabric can be more greatly affected.

[0027] Combinations of thermoplastic resins constituting the composite fiber include, for example, combinations of polyolefin resins and polyester resins such as polyethylene / polyethylene terephthalate, polypropylene / polyethylene terephthalate, and propylene copolymer / polyethylene terephthalate (polyolefin resin / polyester resin), as well as combinations of two types of polyolefin resins such as polyethylene / polypropylene, propylene copolymer / polypropylene, and ethylene-acrylic acid copolymer / polypropylene (polyolefin resin / polyolefin resin), and combinations of two types of polyester resins with different melting points (polyester resin / polyester resin).

[0028] In addition, the thermoplastic resin exemplified as a constituent component of the single fiber or composite fiber may contain other components as long as it contains 50% by mass or more of the specifically shown thermoplastic resin. For example, in the combination of polyethylene / polyethylene terephthalate, "polyethylene" may contain other thermoplastic resins and additives as long as it contains 50% by mass or more of polyethylene. This also applies to the following examples.

[0029] When the adhesive fiber is a core-sheath composite fiber in which a thermoplastic resin with a lower melting point constitutes the sheath portion, the core / sheath combination includes, for example, polyethylene terephthalate / polyethylene, polyethylene terephthalate / polypropylene, polyethylene terephthalate / propylene copolymer, polytrimethylene terephthalate / polyethylene, polybutylene terephthalate / polyethylene, polyethylene terephthalate / copolyester (for example, polyethylene terephthalate copolymerized with isophthalic acid), polypropylene / ethylene-acrylic acid copolymer. Core-sheath composite fibers in which the sheath is polyethylene (for example, high-density polyethylene, low-density polyethylene, or linear low-density polyethylene) or a copolyester have the property that when heat-treated at a temperature equal to or higher than the melting point of the thermoplastic resin constituting the sheath, the sheath melts or softens, and the fibers adhere to each other to form an adhesion site.

[0030] When the adhesive fiber is a core-sheath composite fiber, the composite ratio (volume ratio, core / sheath) of the core and the sheath may be, for example, 80 / 20 to 20 / 80, and particularly may be 60 / 40 to 40 / 60. When the proportion of the sheath is not too small, the adhesion between the fibers becomes more sufficient, the suppression of hairiness becomes more suitable, or the strength of the non-woven fabric may become more suitable. Also, the peeling of the adhesion site during entanglement becomes more appropriate, and further, the suppression of hairiness becomes more suitable, or the strength of the non-woven fabric may become more suitable. When the proportion of the sheath is not too large, the proportion of the core component that maintains the fiber shape becomes more sufficient, and the strength of the non-woven fabric may become more suitable.

[0031] The adhesive fiber may include two or more fibers, and the melting points of the adhesive components of these fibers may be different from each other. For example, the adhesive fiber may include two fibers, and the difference in the melting points of the adhesive components of these fibers may be 10°C or more and 40°C or less, and further may be 15°C or more and 30°C or less.

[0032] The fineness of the adhesive fiber is preferably 1.0 to 7.8 dtex, more preferably 1.4 to 6.7 dtex, and even more preferably 2.2 to 4.5 dtex. When the fineness of the adhesive fiber is within the above range, it is preferable that the strength of the nonwoven fabric is further improved and the texture of the nonwoven fabric becomes softer.

[0033] The fiber diameter of the adhesive fiber is preferably 10 to 33 μm, more preferably 12 to 30 μm, and even more preferably 15 to 25 μm. When the fiber diameter of the adhesive fiber is within the above range, it is preferable that the strength of the nonwoven fabric is further improved and the texture of the nonwoven fabric becomes softer.

[0034] The fiber length of the adhesive fiber is preferably 25 to 100 mm, more preferably 30 to 70 mm, and even more preferably 35 to 60 mm. When the fiber length of the adhesive fiber is within the above range, the entanglement property of the fiber becomes more suitable, which is preferable. In particular, the nonwoven fabric of the present disclosure can be manufactured by performing an entanglement treatment after once adhering the constituent fibers with the adhesive fiber. Therefore, by not having the fiber length too large, the number of adhesion points in one fiber becomes more appropriate, and the entanglement property of the fiber can be made more suitable to sufficiently suppress the hairiness. Also, by not having the fiber length too small, the number of adhesion points in one fiber becomes more appropriate, and the entanglement property of the fiber can be made more suitable to sufficiently soften the texture of the nonwoven fabric.

[0035] The adhesive fiber preferably has a three-dimensional crimp. In this specification, the term "three-dimensional crimp" is used to distinguish from mechanical crimp where the peak (or the top of the peak) of the crimp is an acute angle. The three-dimensional crimp refers to, for example, a crimp where the peak part is curved (wave-shaped crimp), a crimp where the peak part is curved in a spiral shape (spiral crimp), a crimp where the wave-shaped crimp and the spiral crimp are mixed, or a crimp where at least one of the acute-angle crimp of the mechanical crimp and the wave-shaped crimp and the spiral crimp are mixed. The adhesive fiber may have a mechanical crimp. When the adhesive fiber is a composite fiber, it may be an apparent crimp composite fiber. The "apparent crimp composite fiber" refers to a fiber that exhibits a three-dimensional crimp at the fiber stage. The apparent crimp composite fiber is different from the latent crimp composite fiber that exhibits a three-dimensional crimp by heat treatment accompanied by fiber shrinkage.

[0036] When the adhesive fiber is an eccentric core-sheath type composite fiber, the eccentricity is preferably 5 to 50%, more preferably 7 to 30%. The eccentricity referred to here is defined by the following formula. (Formula) Eccentricity (%) = (distance between the center of the single fiber and the center of the core component) × 100 / (single fiber radius) When the adhesive fiber has a three-dimensional crimp, it is more preferable and easier to obtain a nonwoven fabric that shows values within a specific range for the adhesive intersection index A of the nonwoven fabric, the thickness reduction rate of the nonwoven fabric, the stiffness-flexibility per unit thickness of the nonwoven fabric, the thickness ratio of the nonwoven fabric, the angle of the fiber adhesion point in the middle when the nonwoven fabric is trisected in the thickness direction, etc. The adhesive fibers can be used alone or in combination.

[0037] In the nonwoven fabric of the form of the present invention, the mixing ratio (cellulosic fiber:adhesive fiber) (mass ratio) of the cellulosic fiber and the adhesive fiber is preferably 10:90 to 90:10, more preferably 25:75 to 75:25, and even more preferably 35:65 to 65:35. When the mixing ratio (cellulosic fiber:adhesive fiber) (mass ratio) of the cellulosic fiber and the adhesive fiber is within the above range, both the softness of the texture of the nonwoven fabric and the suppression of lint can be further improved, which is preferable. In addition, when an appropriate amount of cellulosic fiber is contained, the effect of the cellulosic fiber can be more easily obtained. In addition, when an appropriate amount of cellulosic fiber is contained, the entanglement of the fibers can be more easily performed, and it is more preferable and easier to obtain a nonwoven fabric that shows values within a specific range for the adhesive intersection index A of the nonwoven fabric, the thickness reduction rate of the nonwoven fabric, the stiffness-flexibility per unit thickness of the nonwoven fabric, the thickness ratio of the nonwoven fabric, the angle of the fiber adhesion point in the middle when the nonwoven fabric is trisected in the thickness direction, etc. In addition, when an appropriate amount of adhesive fiber is contained, both the suppression of lint of the nonwoven fabric and the softness of the texture of the nonwoven fabric are further improved, which is preferable. In the nonwoven fabric of the embodiment of the present invention, when the adhesive fiber content is 35% by mass or more, it is preferable because it becomes easier to prevent the fiber web of the nonwoven fabric or the intermediate from being broken, being stretched more than necessary, etc. during conveyance in nonwoven fabric production.

[0038] The nonwoven fabric of the present embodiment may contain fibers other than the cellulose-based fiber and the adhesive fiber (hereinafter referred to as "other fibers"). The other fibers are, for example, natural fibers that are not cellulose-based fibers (such as wool, silk, etc.), synthetic fibers that are not adhesive fibers (for example, synthetic fibers that do not melt or soften when melting the adhesive component of the adhesive fiber and do not exhibit adhesiveness), and are not particularly limited as long as the nonwoven fabric aimed at by the present invention can be obtained. The other fibers may be contained in a proportion of 35% by mass or less, particularly 25% by mass or less, more particularly 10% by mass or less, and are not particularly limited as long as the nonwoven fabric aimed at by the present invention can be obtained. The nonwoven fabric of the present embodiment may be a nonwoven fabric that does not contain other fibers, that is, a nonwoven fabric composed of a cellulose-based fiber and an adhesive fiber.

[0039] In the nonwoven fabric of the present embodiment, the fibers are adhered to each other by the adhesive fiber. That is, the nonwoven fabric of the embodiment of the present invention includes an adhered portion. Thereby, both the strength of the nonwoven fabric and the suppression of fluff are ensured, and the handleability is improved. The adhesion by the adhesive fiber can be achieved by a part of the adhesive fiber melting, softening, or deteriorating to exhibit adhesiveness and fixing the fibers that cross or contact it. The adhesion between the fibers specifically refers to the adhesion between the adhesive fibers, the adhesion between the adhesive fiber and the cellulose-based fiber, and when other fibers are further included, it also refers to the adhesion between the adhesive fiber and the other fibers. The adhesion may be by thermal adhesion in which heat is applied to melt or soften a part of the adhesive fiber, or may be by irradiation with an electron beam or the like or ultrasonic welding.

[0040] In the nonwoven fabric of this embodiment, the fibers are entangled with each other. That is, the nonwoven fabric of the form of the present invention includes entanglement portions. Thereby, both the strength of the nonwoven fabric and the suppression of fluff are ensured, and the handleability is improved. The entanglement of the fibers can be achieved by entangling the fibers with each other, for example, by subjecting the nonwoven fabric to a material flow. Specifically, the entanglement of the fibers refers to the entanglement of adhesive fibers with adhesive fibers, the entanglement of adhesive fibers with cellulose-based fibers, and the entanglement of cellulose-based fibers with cellulose-based fibers. When other fibers are further included, in addition, it refers to the entanglement of adhesive fibers with other fibers, the entanglement of cellulose-based fibers with other fibers, and the entanglement of other fibers with other fibers. The entanglement may be by the needle punching method or by a fluid flow, and the fluid flow may be by a water flow, an air flow, a water vapor flow, or the like. In the nonwoven fabric of this embodiment, it is preferably by a water flow or a water vapor flow in order to entangle the cellulose-based fibers.

[0041] The nonwoven fabric of this embodiment preferably has a basis weight of 10 to 150 g / m 2 and more preferably has a basis weight of 15 to 80 g / m 2 and still more preferably has a basis weight of 20 to 60 g / m 2 and particularly preferably has a basis weight of 25 to 50 g / m 2 By the basis weight not being too small, both the softness of the texture of the nonwoven fabric and the suppression of fluff are further improved, which is preferable. Also, by the basis weight not being too small, the entanglement progresses more moderately throughout the nonwoven fabric, and for the adhesive intersection index A of the nonwoven fabric, the thickness reduction rate of the nonwoven fabric, the rigidity-flexibility per unit thickness of the nonwoven fabric, the thickness ratio of the nonwoven fabric, the angle of the fiber adhesion points in the middle when the nonwoven fabric is trisected in the thickness direction, etc., it is possible to more easily obtain a nonwoven fabric showing values within a specific range. By the basis weight not being too large, the strength of the nonwoven fabric and the suppression of fluff can be further improved.

[0042] As a whole, the nonwoven fabric of this embodiment may have a fiber density of, for example, 0.0100 to 0.100 g / cm when dry 3 and may have a fiber density of 0.0125 to 0.0600 g / cm 3Preferably having a fiber density of 0.0180 to 0.0400 g / cm 3 More preferably having a fiber density of 3 . The fiber density of the entire nonwoven fabric can be determined from the basis weight and thickness (thickness measured under a load of 40 Pa).

[0043] When observing the cross-section cut along the thickness direction of the nonwoven fabric of this embodiment, it is preferable that the fiber density of at least one surface (that is, the front surface or the back surface) is higher than the fiber density inside. In this embodiment, it is more preferable that the fiber density is higher than the fiber density inside on both the front surface and the back surface. When the fiber density of at least one surface is higher than the fiber density inside, both the softness of the texture of the nonwoven fabric and the suppression of fuzz can be further improved, so it is more preferable. Whether there is a difference between the fiber density inside the nonwoven fabric and the fiber density on the surface can be examined by observing the cross-section cut along the thickness direction of the nonwoven fabric with an electron microscope (magnification of about 50 times). More specifically, when observed with an electron microscope, the part where the fibers are more densely aggregated is a region with a higher fiber density, and the part where the fibers are more sparsely aggregated is a region with a lower fiber density.

[0044] The high or low fiber density can be confirmed, for example, by counting the number of cross-sections of the cut fibers per unit area with an electron microscope (magnification of about 50 times) in the cross-section cut along the thickness direction of the nonwoven fabric. More specifically, when the cross-section of the nonwoven fabric is divided into five equal parts along the thickness direction, the upper and lower one-fifth parts are defined as the "surface of the nonwoven fabric" (the "upper surface" (front surface) and the "lower surface" (back surface) respectively), and when the upper one-fifth part and the lower one-fifth part are excluded from the cross-section of the nonwoven fabric divided into five equal parts along the thickness direction, and the middle three-fifths part is defined as the "inside of the nonwoven fabric", if the ratio of the number of fiber cross-sections on the surface of the nonwoven fabric to the number of fiber cross-sections inside the nonwoven fabric is 1.05 or more, it can be regarded that the fiber density on the surface of the nonwoven fabric is higher than that inside.

[0045] In the nonwoven fabric of the present embodiment, it is preferable that an adhesive peeling mark where the adhered part by the adhesive fiber is eliminated is formed on the adhesive fiber. The adhesive peeling mark can be mainly formed by the entanglement treatment after the adhesion treatment. In the adhesive peeling mark, the adhesive component (for example, the sheath component in the case of a core-sheath type composite fiber) is present thinly as compared with the fiber surface of a normal adhesive fiber. Due to this adhesive peeling mark, the fiber becomes easy to bend, and the softness of the texture of the nonwoven fabric can be improved. Therefore, it is preferable that the adhesive peeling mark is appropriately included. The adhesive peeling mark can be confirmed by observing the surface and cross-section of the nonwoven fabric using an electron microscope.

[0046] In the nonwoven fabric of the present embodiment, another nonwoven fabric may be laminated on one surface of the nonwoven fabric, but it is preferable that at least one surface is in an exposed form. It is more preferable that both surfaces of the nonwoven fabric are in an exposed form. Note that the nonwoven fabric of the present embodiment may have a single-layer structure, but as a laminated structure, for example, the mixing ratio of the cellulose-based fiber and the adhesive fiber may be changed in each layer. When the nonwoven fabric of the present embodiment has a single-layer structure, it is preferable because it can have both suppression of fuzzing and softness of the texture on both surfaces of the nonwoven fabric. Further, when the nonwoven fabric has a single-layer structure, it is preferable because it can suppress delamination between layers and a decrease in the strength of the nonwoven fabric due to a weak degree of entanglement, and can also suppress a reduction in the softness of the texture due to a strong degree of entanglement. Since the nonwoven fabric of the present embodiment has both good softness of the texture and suppression of fuzzing, it is suitable for uses in which the nonwoven fabric of the present embodiment is exposed, such as a topsheet and a backsheet for absorbent articles, a liquid-impregnated skin covering material impregnated with a liquid such as cosmetics (for example, a face mask, a cutin care sheet, and a décolleté sheet), a base fabric for various poultice materials including warm compresses and cold compresses, a wiping material for humans (for example, a cleansing sheet, an antiperspirant sheet, and a sterilizing sheet), disposable clothing, and the like.

[0047] When the nonwoven fabric of the present embodiment has a laminated structure, it is preferable because each layer can have different performances. For example, the texture of the nonwoven fabric can be improved in one layer, and the suppression of fuzz can be improved in the other layer. The degree of hydrophilicity can be changed for each layer. At least two layers can contain adhesive fibers, and adhesive fibers with different melting points of the adhesive component can be included for each layer.

[0048] The nonwoven fabric of the form of the present invention preferably has an adhesive intersection index A of the nonwoven fabric described in the following examples of 1 to 60 pieces / mm 2 The upper limit of the adhesive intersection index A is more preferably 55 pieces / mm 2 even more preferably 50 pieces / mm 2 even further preferably 45 pieces / mm 2 and particularly preferably 45 pieces / mm. The lower limit of the adhesive intersection index A is more preferably 3 pieces / mm 2 even more preferably 5 pieces / mm 2 even further preferably. When the adhesive intersection index A of the nonwoven fabric of the form of the present invention is within the above range, the texture of the nonwoven fabric becomes more suitable and preferable.

[0049] The nonwoven fabric of the form of the present invention preferably has a thickness reduction rate of the nonwoven fabric described in the following examples of 30 to 45%, more preferably 32 to 43%, and even further preferably 34 to 41%. When the thickness reduction rate of the nonwoven fabric of the form of the present invention is within the above range, the texture of the nonwoven fabric becomes more suitable and preferable.

[0050] The nonwoven fabric of the form of the present invention preferably has a stiffness-flexibility per unit thickness of the nonwoven fabric described in the following examples of 10 to 85 g / mm, more preferably 20 to 70 g / mm, even further preferably 30 to 60 g / mm, and particularly preferably 35 to 55 g / mm. When the stiffness-flexibility per unit thickness of the nonwoven fabric of the form of the present invention is within the above range, the texture of the nonwoven fabric becomes more suitable and preferable.

[0051] For the nonwoven fabric of the embodiment of the present invention, the thickness ratio of the nonwoven fabric described in the following examples is, for example, 0.25 to 0.69, preferably 0.25 to 0.67, more preferably 0.35 to 0.65, and even more preferably 0.40 to 0.60. For the nonwoven fabric of the embodiment of the present invention, when the thickness ratio of the nonwoven fabric is within the above range, the softness of the texture of the nonwoven fabric becomes more suitable and preferable. Further, the thickness ratio of the nonwoven fabric is an index suggesting the ratio of the fibers oriented in a direction parallel to the thickness direction of the nonwoven fabric (a direction more perpendicular to the surface of the nonwoven fabric) with respect to the fibers constituting the nonwoven fabric. The smaller the thickness ratio, the higher the ratio of the fibers oriented in a direction more parallel to the thickness direction of the nonwoven fabric.

[0052] For the nonwoven fabric of the embodiment of the present invention, when the nonwoven fabric described in the following examples is trisected in the thickness direction, the angle of the fiber adhesion points in the middle of the nonwoven fabric is preferably 30 to 90 degrees, more preferably 35 to 60 degrees, and even more preferably 40 to 50 degrees. For the nonwoven fabric of the embodiment of the present invention, when the angle of the fiber adhesion points in the middle of the nonwoven fabric is within the above range, the softness of the texture of the nonwoven fabric becomes more suitable and preferable.

[0053] For the nonwoven fabric of the embodiment of the present invention, regarding the breaking strength described in the following examples, the breaking strength in the MD direction is preferably 10 to 100 N, more preferably 15 to 70 N, the breaking strength in the CD direction is preferably 1 to 25 N, and more preferably 2 to 12 N. For the nonwoven fabric of the embodiment of the present invention, when the strength of the nonwoven fabric is within the above range, the handleability is further improved and preferable.

[0054] For the nonwoven fabric of the embodiment of the present invention, the water retention rate described in the following examples is preferably 800 to 2500%, more preferably 1000 to 2000%, even more preferably 1100 to 1800%, and particularly preferably 1250 to 1650%. For the nonwoven fabric of the embodiment of the present invention, when the water retention rate of the nonwoven fabric is within the above range, it has suitable liquid impregnation properties or liquid retention properties and is preferable. Further, the nonwoven fabric of the embodiment of the present invention preferably has a water retention rate per unit thickness (water retention rate / thickness) of 1500 to 3000%, more preferably 1700 to 2800%, and even more preferably 1900 to 2600%. The thickness of the nonwoven fabric at this time is the thickness obtained by applying a load of 1.96 kPa described later. When the water retention rate of the nonwoven fabric of the embodiment of the present invention is within the above range, it has suitable liquid impregnation properties or liquid retention properties, which is preferable.

[0055] For the nonwoven fabric of the embodiment of the present invention, the coefficient of variation CV of the dynamic frictional force, which will be described in the following examples, is, for example, 0.081 or less, preferably 0.070 or less, more preferably 0.060 or less, and even more preferably 0.055 or less. The preferable lower limit of the coefficient of variation CV of the dynamic frictional force is 0.00. When the coefficient of variation CV of the dynamic frictional force of the nonwoven fabric of the embodiment of the present invention is within the above range, the surface of the nonwoven fabric becomes smoother, which is preferable.

[0056] The method for manufacturing the nonwoven fabric of the present invention is a method for manufacturing a nonwoven fabric containing cellulosic fibers and adhesive fibers, and includes an adhesion step of adhering the fibers together with the adhesive fibers and an entanglement step of entangling the fibers after the adhesion step.

[0057] (Method for manufacturing nonwoven fabric) The nonwoven fabric of the present embodiment can be manufactured by mixing cellulosic fibers, adhesive fibers, and, if included, other fibers to produce a fiber web, adhering the fibers together with the adhesive fibers to provide adhesion points, and entangling the fibers to provide entanglement points. The fiber web can be produced by a known method. The form of the fiber web may be any form such as a card web such as a parallel web, a cross web, a semi-random web, and a random web, an airlaid web, or a wet-laid web. The form of the fiber web is preferably a parallel web because the surface of the nonwoven fabric becomes smoother.

[0058] In the case of a laminated nonwoven fabric, for example, two fiber webs are produced, the two fiber webs are laminated to obtain one web, and then the fibers are adhered to each other with adhesive fibers to provide an adhered portion, and the fibers are entangled with each other to provide an entangled portion, whereby it can be manufactured. Incidentally, as the entire fiber web, it may include cellulose-based fibers and adhesive fibers.

[0059] The fiber web is subjected to an adhesion treatment (or adhesion step). The adhesion treatment may be, for example, a heat treatment (thermal adhesion treatment). According to the heat treatment, the component having the lowest melting point (thermal adhesion component) among the resin components constituting the adhesive fiber is melted or softened by heating during the heat treatment, and the fibers constituting the fiber web can be adhered to each other. The heat treatment may be, for example, a hot air processing treatment of blowing hot air, a heat roll processing (for example, a hot embossing roll processing), or a heat treatment using infrared rays, but the hot air processing treatment is preferable in order to improve the texture of the nonwoven fabric. The hot air processing treatment may be carried out using a device that blows hot air at a predetermined temperature onto the fiber web, for example, a hot air penetration type heat treatment machine and a hot air blowing type heat treatment machine.

[0060] When the adhesion treatment is a hot air processing treatment, it is preferable to blow hot air a plurality of times. Further, when blowing hot air a plurality of times, it is preferable that the temperature of the second hot air is higher than the temperature of the first hot air. Since the adhesiveness between the cellulose-based fiber and the adhesive fiber is not higher than the adhesiveness between the adhesive fibers, it is effective to blow hot air a plurality of times in order to further increase the adhesiveness between the cellulose-based fiber and the adhesive fiber.

[0061] When the adhesion treatment is a hot air processing treatment, the wind speed of the hot air is preferably 0.1 to 3.0 m / min, more preferably 0.2 to 2.5 m / min, and even more preferably 0.3 to 2.0 m / min from the viewpoint of suppressing fuzzing and improving the softness of the texture.

[0062] The heat treatment temperature may be the temperature at which the component with the lowest melting point (heat - adhesive component) among the resin components constituting the adhesive fiber softens or melts. For example, it may be a temperature equal to or higher than the melting point of the component. For example, when the component with the lowest melting point among the resin components constituting the adhesive fiber is high - density polyethylene, when performing hot - air processing, hot air at a temperature of 130°C to 150°C may be blown. For example, when the component with the lowest melting point among the resin components constituting the adhesive fiber is an ethylene - acrylic acid copolymer, when performing hot - air processing, hot air at a temperature of 90°C to 140°C may be blown, particularly hot air at a temperature of 95 to 130°C may be blown, and more particularly hot air at a temperature of 100 to 120°C may be blown. Also, from the viewpoint of suppressing fuzzing and making the texture soft, the heat treatment temperature is preferably 0°C or more and 5°C or less higher than the melting point or softening point of the heat - adhesive component, more preferably 1°C or more and 4°C or less higher, and even more preferably 2°C or more and 3°C or less higher.

[0063] The adhesion treatment may be by irradiation such as electron beam or ultrasonic welding. Also by these adhesion treatments, the fibers can be adhered to each other with the resin components constituting the adhesive fiber.

[0064] For the fiber web after the adhesion treatment and before the entanglement treatment, for example, when the breaking strength in the MD direction is 1.0 N / 5 cm or more, the adhesion is sufficient and it is easy to obtain the non - woven fabric of the present disclosure with good fuzz suppression, which is preferable. More preferably, the breaking strength in the MD direction is 2.0 N / 5 cm or more, and even more preferably 3.0 N / 5 cm or more. Also, for the fiber web after the adhesion treatment and before the entanglement treatment, for example, when the stiffness - softness obtained by the method described in the examples is 100 g or less, it is easy to obtain the non - woven fabric of the present disclosure with good soft texture, which is preferable. More preferably, the stiffness - softness is 80 g or less, and even more preferably 60 g or less.

[0065] The fiber web is further subjected to entanglement treatment (or entanglement process). Examples of the entanglement treatment include, for example, water stream entanglement treatment and water vapor stream entanglement treatment, etc., and it is preferable to include any of these. It is preferable that the entanglement process includes water stream entanglement treatment. According to these entanglement treatments, entanglement by cellulose fibers can be easily performed, and a nonwoven fabric having desired physical properties can be obtained.

[0066] The manufacturing method of the embodiment of the present invention preferably includes a cooling treatment (or cooling process) between the adhesion treatment (or adhesion process) and the entanglement treatment (or entanglement process). That is, after being subjected to the adhesion treatment and before being subjected to the entanglement treatment, the fiber web is preferably subjected to a cooling treatment (or cooling process). Examples of the cooling process include air cooling or water cooling. If the fiber web after being subjected to the adhesion treatment is not sufficiently cooled, the adhesive component of the adhesive fiber may be in a softened state. When the fiber web in that state is subjected to the entanglement treatment, the adhered portions may be easily peeled off, and the suppression of the fluffing of the nonwoven fabric may be insufficient.

[0067] The water stream entanglement treatment can be carried out by placing the fiber web on a support and spraying a columnar water stream. If the support is flat on the nonwoven fabric surface and has no unevenness, it is preferable to use a support having no openings with an opening area per one exceeding 0.2 mm 2 and no protrusions or patterns formed. For example, as the support, a plain woven support of 80 mesh or more and 100 mesh or less may be used.

[0068] The water stream entanglement treatment can be carried out, for example, by spraying a water stream with a water pressure of 1 MPa or more and 15 MPa or less from a nozzle in which orifices with a pore diameter of 0.05 mm or more and 0.5 mm or less are provided at intervals of 0.3 mm or more and 1.5 mm or less, one to five times each on the front and back surfaces of the fiber web. The water pressure is preferably 1 MPa or more and 10 MPa or less, and more preferably 1 MPa or more and 7 MPa or less.

[0069] The support used in the water entanglement treatment may be a plate-shaped or roll-shaped support, and a roll-shaped support is preferred. When the support is roll-shaped, the fiber web curves, and the fiber density becomes smaller in the thickness direction of the fiber web (or the outer direction of the usually curved web). When a columnar water flow is injected from the outside, the entanglement by the columnar water flow is relatively likely to proceed. In the nonwoven fabric of the present embodiment, it is preferable that the fiber web is subjected to an adhesion treatment and then an entanglement treatment in this order. When the fiber web is subjected to an entanglement treatment after the adhesion treatment, since the fiber web contains adhesion points and it is relatively difficult for entanglement to proceed, it is preferable to perform the water entanglement treatment in a state where entanglement is more likely to proceed.

[0070] When the adhesion treatment is a hot air processing treatment, the water entanglement treatment preferably includes injecting a columnar water flow first from the side where hot air was blown in the hot air processing treatment, and further preferably includes injecting a columnar water flow from the opposite side. The side where hot air was blown in the hot air processing treatment tends to have a smaller fiber density than the opposite side (generally the side in contact with the support), and the entanglement by the columnar water flow is relatively likely to proceed. Since the strength of the nonwoven fabric and the degree of suppression of hairiness by the water entanglement treatment are greatly influenced by the degree of entanglement in the first entanglement treatment, it is preferable to perform the injection of the columnar water flow from the side where the fiber density of the fiber web is relatively small and entanglement is relatively likely to proceed.

[0071] When the entanglement treatment is a water entanglement treatment, the fiber web is preferably subjected to a drying treatment (drying process) after the entanglement treatment. The drying treatment can be performed by a hot air processing treatment or the like that blows hot air. The temperature of the drying treatment is preferably lower than the temperature at which the adhesion component (heat adhesion component) of the adhesive fiber softens or melts. The temperature of the drying treatment is preferably 10°C or more lower than the melting point or softening point of the heat adhesion component, more preferably 15°C or more lower, and even more preferably 20°C or less lower. If the adhesive component is not softened or melted again after the entanglement treatment, the bulkiness of the nonwoven fabric is less likely to decrease, and the texture of the nonwoven fabric is less likely to become hard.

[0072] When containing two or more adhesive fibers and the melting points or softening points of the heat - adhesive components of the respective adhesive fibers are different, if the melting point or softening point of the heat - adhesive component with a higher melting point or softening point is T1 (°C), the melting point or softening point of the heat - adhesive component with a lower melting point or softening point is T2 (°C), and the temperature of the drying treatment is T (°C), it is preferable that T1, T2, and T satisfy the relationship of T2 ≤ T < T1. In particular, it is preferably T ≤ T1 + 10, more particularly preferably T ≤ T1 + 15, and even more particularly preferably T ≤ T1 + 20. When the non - woven fabric contains two or more adhesive fibers, has a laminated structure, and the melting points or softening points of the heat - adhesive components of the adhesive fibers are different for each layer in at least two layers, by setting the temperature of the drying treatment to T2 ≤ T < T1, the texture of the non - woven fabric can be improved in the layer containing the adhesive fiber with a melting point or softening point of T1, and the strength and suppression of hairiness of the non - woven fabric can be improved in the layer containing the adhesive fiber with a melting point or softening point of T2.

[0073] The fiber web is preferably subjected to the adhesion treatment and the entanglement treatment in this order. When subjected to the heat - adhesion treatment and the entanglement treatment in this order, it is preferable because the entanglement of the fibers proceeds moderately and a more suitable softness of the texture can be obtained. The entanglement treatment is preferably applied continuously after the adhesion treatment. When the fiber web subjected to the adhesion treatment is, for example, once wound into a roll and then subjected to the entanglement treatment, the softness of the texture is likely to be reduced by the winding pressure, and hairiness is likely to occur due to the friction between the fiber webs during unwinding.

[0074] In the heat - adhesion treatment, it is preferable to heat so that the low - melting - point component of the adhesive fiber melts, and it is more preferable to heat so that only the low - melting - point component melts. By the appropriate melting of the low - melting - point component, adhesion points of a more appropriate size and a more appropriate number can be formed, and the softness of the texture of the non - woven fabric can be further improved. By adjusting the heat - treatment temperature, the degree of heat - adhesion by the low - melting - point component (for example, the size and number of adhesion points, etc.) can also be changed. By adjusting the degree of heat - adhesion, the strength of the non - woven fabric, the suppression of hairiness, and the softness of the texture, etc. can be further improved, and the degree of entanglement can also be adjusted.

[0075] The nonwoven fabric of the form of the present invention can be used, for example, in absorbent articles such as disposable diapers, sanitary napkins, incontinence pads, and pantiliners, wiping materials for humans or objects, skin covering materials such as face masks impregnated with cosmetics, gauze, disposable clothing, etc. Furthermore, it has an excellent balance of overall properties and is suitable for applications that directly contact human skin, etc., such as top sheets and back sheets for absorbent articles, liquid-impregnated skin covering materials impregnated with liquids such as cosmetics (for example, face masks, cutin care sheets, and décolleté sheets, etc.), base fabrics for various poultice materials including warm compresses and cold compresses, wiping materials for humans (for example, cleansing sheets, antiperspirant sheets, and antibacterial sheets, etc.).

Examples

[0076] The present invention will be described below using examples and comparative examples. These examples are for illustrative purposes only and do not limit the present invention in any way.

[0077] The fibers used to produce the nonwoven fabrics of the examples and comparative examples are shown below. Fiber 1 (cellulosic fiber): Solvent-spun cellulose fiber with a fineness of 1.7 dtex and a fiber length of 40 mm (Lyocell (trade name) manufactured by Lenzing). The sedimentation rate is 4 seconds. Fiber 2 (adhesive fiber): An eccentric core-sheath type composite fiber with a fineness of 2.6 dtex, a fiber length of 51 mm, and an eccentricity of 25% having a three-dimensional crimp, where polyethylene terephthalate is the core and high-density polyethylene (melting point: about 133°C) is the sheath (NBF(SH)V (trade name) manufactured by Daiwabo Polytech Co., Ltd.). Fiber 3 (adhesive fiber): A concentric core-sheath type composite fiber with a fineness of 3.3 dtex and a fiber length of 51 mm having a mechanical crimp, where polypropylene (melting point 160°C) is the core and ethylene-acrylic acid copolymer (acrylic acid 8.5 - 10% by mass) (melting point 95°C) is the sheath (NBF(A) (trade name) manufactured by Daiwabo Polytech Co., Ltd.). Fiber 4 (cellulose fiber): Cotton (MSD (trade name) manufactured by Marusan Sangyo Co., Ltd.) with a fineness of 1.0 to 5.0 dtex (average 2.5 dtex) and a fiber length of 10 to 60 mm. The sedimentation rate is 10 seconds. Fiber 5 (cellulose fiber): Water-repellent rayon with a fineness of 1.7 dtex and a fiber length of 40 mm. The sedimentation rate is that it does not sink in 5 minutes or more.

[0078] <Manufacture of nonwoven fabrics of Examples 11 to 13> Fibers 1 and 2 were used at a mixing ratio of 2:8 (mass ratio), and a fiber web was produced using a parallel carding machine. The basis weight of this fiber web was about 35 g / m 2 It was. This fiber web was heated at 135°C for about 5 seconds using a hot air through-type heat treatment machine. An air-through nonwoven fabric in which the fibers were thermally bonded (bonding treatment) by the sheath component of Fiber 2 was obtained. After the thermal bonding (bonding treatment), the air-through nonwoven fabric was subjected to a cooling treatment by air cooling at room temperature of 20°C. The above-mentioned air-through nonwoven fabric was placed on a plain-woven PET net with a warp wire diameter of 0.132 mm, a weft wire diameter of 0.132 mm, and a mesh count of 90 meshes. While advancing the air-through nonwoven fabric at a speed of 4 m / min, a columnar water flow with a water pressure of 2.0 MPa was sprayed onto the surface of the air-through nonwoven fabric using a water supply device. The nozzles of the water supply device were provided with orifices with a pore diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the air-through nonwoven fabric and the orifices was 15 mm. Then, a columnar water flow was similarly sprayed onto the back surface of the air-through nonwoven fabric using a water supply device. In this way, the fibers were entangled by the water flow (entanglement treatment). After the entanglement treatment, a drying treatment was performed using a hot air through-type heat treatment machine set at 80°C to obtain the nonwoven fabric (single layer) of Example 11. A nonwoven fabric of Example 12 was obtained using the same method as in Example 11, except that a columnar water flow with a water pressure of 3.0 MPa was sprayed on each of the front and back surfaces (both sides). A nonwoven fabric of Example 13 was obtained using the same method as in Example 11, except that a columnar water flow with a water pressure of 3.5 MPa was sprayed on each of the front and back surfaces.

[0079] <Manufacture of nonwoven fabrics of Examples 21 to 23> A nonwoven fabric of Example 21 was obtained in the same manner as in Example 11, except that Fiber 1 and Fiber 2 were used at a mixing ratio of 4:6. A nonwoven fabric of Example 22 was obtained in the same manner as in Example 21, except that a columnar water flow with a water pressure of 3.0 MPa was sprayed on each of the front and back surfaces. A nonwoven fabric of Example 23 was obtained in the same manner as in Example 21, except that a columnar water flow with a water pressure of 3.5 MPa was sprayed on each of the front and back surfaces.

[0080] <Production of Nonwoven Fabrics of Examples 31 to 33> Nonwoven fabrics of Examples 31 to 33 were obtained in the same manner as in Examples 21 to 23, except that Fiber 1 and Fiber 2 were used at a mixing ratio of 6:4. <Production of Nonwoven Fabrics of Examples 41 to 43> Nonwoven fabrics of Examples 41 to 43 were obtained in the same manner as in Examples 21 to 23, except that Fiber 1 and Fiber 2 were used at a mixing ratio of 8:2.

[0081] <Production of Nonwoven Fabric of Comparative Example 50> A nonwoven fabric of Comparative Example 50 was obtained in the same manner as in Example 11, except that Fiber 1 and Fiber 2 were used at a mixing ratio of 6:4 and the treatment with water flow and the drying treatment were not performed. <Production of Nonwoven Fabrics of Comparative Examples 61 to 62> A nonwoven fabric of Comparative Example 61 was obtained in the same manner as in Example 11, except that Fiber 1 and Fiber 2 were used at a mixing ratio of 6:4 and the heat treatment (adhesion treatment) and the cooling treatment were not performed. A nonwoven fabric of Comparative Example 62 was obtained in the same manner as in Comparative Example 61, except that a water flow with a water pressure of 3.0 MPa was used on each of the front and back surfaces.

[0082] <Production of Nonwoven Fabrics of Comparative Examples 71 to 72> A fiber web was produced using Fiber 1 and Fiber 2 at a mixing ratio of 6:4. A nonwoven fabric of Comparative Example 71 was obtained in the same manner as in Example 11, except that a columnar water flow with a water pressure of 2.0 MPa was sprayed on each of the front and back surfaces of the fiber web and then heat treatment was performed at 135°C for about 5 seconds using a hot air through-type heat treatment machine. A nonwoven fabric of Comparative Example 72 was obtained in the same manner as in Comparative Example 71, except that columnar water streams with a water pressure of 3.0 MPa were sprayed onto the front and back surfaces, respectively.

[0083] <Production of the nonwoven fabric of Example 81> Fiber 1 and Fiber 2 were prepared at a mass ratio of 6:4, and each fiber web was produced using a parallel carding machine with only each of the fibers. The total basis weight of these two fiber webs was about 35 g / m 2 It was. The fiber web obtained by laminating these two fiber webs was heated at 135°C for about 5 seconds using a hot air through-type heat treatment machine. An air-through nonwoven fabric in which the fibers were thermally bonded (bonding treatment) by the sheath component of Fiber 2 was obtained. The hot air was applied from the side of the fiber web containing Fiber 1. After the thermal bonding (bonding treatment), a cooling treatment of the air-through nonwoven fabric was performed by air cooling at room temperature of 20°C. The above-mentioned air-through nonwoven fabric was placed on a plain-woven PET net with a warp yarn diameter of 0.132 mm, a weft yarn diameter of 0.132 mm, and a mesh count of 90 meshes. While advancing the air-through nonwoven fabric at a speed of 4 m / min, a columnar water stream with a water pressure of 3.0 MPa was sprayed onto the surface of the air-through nonwoven fabric (the side of the layer containing Fiber 1) using a water supply device. The nozzles of the water supply device were provided with orifices with a pore diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the air-through nonwoven fabric and the orifices was 15 mm. Then, a columnar water stream was similarly sprayed onto the back surface of the air-through nonwoven fabric using the water supply device. In this way, the fibers were entangled with each other by the water stream (entanglement treatment). After the entanglement treatment, a drying treatment was performed using a hot air through-type heat treatment machine set at 80°C to obtain the nonwoven fabric (laminated) of Example 81.

[0084] <Production of the nonwoven fabric of Example 82> Fiber 1 and Fiber 2 were used at a mixing ratio of 7:3 (mass ratio), and a fiber web A was produced using a parallel carding machine. The basis weight of this fiber web A was about 17.5 g / m 2 It was. Next, Fiber 1 and Fiber 2 were used at a mixing ratio of 5:5 (mass ratio), and a fiber web B was produced using a parallel carding machine. The basis weight of this fiber web B was about 17.5 g / m 2It was. The fiber web obtained by laminating these two fiber webs was heated at 135°C for about 5 seconds using a hot air through-type heat treatment machine. An air-through nonwoven fabric was obtained in which the fibers were thermally bonded (bonding treatment) by the sheath component of fiber 2. The hot air was applied from the side of fiber web A. After the thermal bonding (bonding treatment), a cooling treatment of the air-through nonwoven fabric was performed by air cooling at room temperature of 20°C. The above-mentioned air-through nonwoven fabric was placed on a plain-woven PET net with a warp yarn diameter of 0.132 mm, a weft yarn diameter of 0.132 mm, and a mesh number of 90 meshes. While advancing the air-through nonwoven fabric at a speed of 4 m / min, a columnar water flow with a water pressure of 2.0 MPa was sprayed onto the surface of the air-through nonwoven fabric (the side of fiber web A) using a water supply device. The nozzle of the water supply device was provided with orifices having a pore diameter of 0.12 mm at intervals of 0.6 mm. The distance between the surface of the air-through nonwoven fabric and the orifices was 15 mm. Then, a columnar water flow was similarly sprayed onto the back surface of the air-through nonwoven fabric using the water supply device. In this way, the fibers were entangled with each other (entanglement treatment) by the water flow. After the entanglement treatment, a drying treatment was performed using a hot air through-type heat treatment machine set at 80°C to obtain the nonwoven fabric (laminated) of Example 82. In the entire nonwoven fabric of Example 82, the mixing ratio of fiber 1 and fiber 2 was 6:4 (mass ratio).

[0085] <Manufacture of the nonwoven fabric of Example 83> The nonwoven fabric of Example 83 was obtained using the same method as in Example 82, except that the hot air was applied from the side of fiber web B and the columnar water flow was sprayed first from the side of fiber web B.

[0086] <Manufacture of the nonwoven fabrics of Examples 84 to 86> The nonwoven fabrics (single layer) of Examples 84 to 86 were obtained using the same method as in Example 31, except that fiber 1 and fiber 3, fiber 4 and fiber 2, and fiber 5 and fiber 2 were used at a mixing ratio of 6:4, respectively, instead of fiber 1 and fiber 2.

[0087] The evaluation of the nonwoven fabric was carried out as follows. <Structure of the nonwoven fabric> The structure of the nonwoven fabric was determined by cutting the nonwoven fabric in the longitudinal direction (more specifically, in the direction parallel to the traveling direction of the belt conveyors of the heat treatment machine and the water flow treatment machine that processed the nonwoven fabric), and observing the cut surface with a scanning electron microscope (SEM, magnification: 60 times). The results are shown in Tables 1 to 2. The SEM image of the nonwoven fabric of Example 31 is shown in FIG. 1. It can be seen that the nonwoven fabric of Example 31 has a structure of dense / sparse / dense, that is, the number of fibers inside the nonwoven fabric is less than the number of fibers on the front and back surfaces. The SEM image (magnification: 25 times) of the nonwoven fabric of Comparative Example 50 is shown in FIG. 2. It can be seen that the nonwoven fabric of Comparative Example 50 has substantially no difference in the number of fibers inside the nonwoven fabric and the number of fibers on the front and back surfaces, and does not have a dense / sparse / dense structure.

[0088] <Adhesion point angle measurement> Regarding the photographed SEM images, for the vicinity of the front and back surfaces and the vicinity of the middle (inside) of the nonwoven fabric when the nonwoven fabric was divided into three equal parts in the thickness direction, the angle formed by only the two fibers forming the adhesion point was examined. The angles formed by at least 4 pairs of fibers were examined and their average value was obtained. The results are described in Tables 1 to 2. For the examples and comparative examples processed by the hot air penetration type heat treatment machine, the side where the hot air was applied was regarded as the front surface, and the opposite side was regarded as the back surface.

[0089] <Adhesion intersection index A> The front and back surfaces of the nonwoven fabric were observed with a scanning electron microscope (SEM, acceleration voltage: 10.0 kV, magnification: 100 times). Regarding the photographed SEM images, the number of fiber adhesion intersections per unit area was counted. For 3 SEM images each of the front and back surfaces of the nonwoven fabric, a total of 6 SEM images, the number of fiber adhesion intersections was counted, and the average value was taken as the number of fiber adhesion intersections I (unit: pieces / mm 2 ) From the fineness (dtex) of the non-adhesive fibers (fiber 1) and the adhesive fibers (fiber 2) constituting the nonwoven fabrics of the examples and comparative examples and the mixing ratio (mass%) in the nonwoven fabric, the adhesion intersection ratio P (0 ≦ P ≦ 1) was obtained according to the following formula.

Equation

[0090] In addition, in the case of a two-layer structure, the adhesion intersection ratio P of the front or back surface is calculated according to the cotton blending state of the front or back surface, respectively. The calculation of the adhesion intersection index A remains the average value of three for the front surface and three for the back surface. In the case of Example 81, the adhesion intersection index A of the surface of Fiber 1 is 0 (I = 0). The adhesion intersection index A of the surface of Fiber 2 is 28 (P = 1). On average, the adhesion intersection index A of Example 81 is 14.

[0091] <Thickness and density of non-woven fabric> Using a thickness measuring machine (THICKNESS GAUGE model CR-60A (trade name) manufactured by Dai-ichi Kagaku Seiki Co., Ltd.), the thickness of the non-woven fabric was measured with a load of 1.96 kPa applied to the non-woven fabric. Alternatively, using a CCD laser displacement meter (amplifier unit type: LK-2100, sensor head type: LK-080, manufactured by Keyence Corporation), the thickness of the non-woven fabric was measured with a load of 40 Pa applied to the non-woven fabric. The results are shown in Tables 1-2. The density of the non-woven fabric was calculated based on the basis weight of the non-woven fabric and the thickness of the non-woven fabric obtained with a load of 40 Pa applied. In addition, the ratio of the thickness obtained with a load of 1.96 kPa applied to the thickness obtained with a load of 40 Pa applied (thickness obtained with a load of 1.96 kPa applied / thickness obtained with a load of 40 Pa applied) is defined as the "thickness ratio".

[0092] <Thickness reduction rate of non-woven fabric> For a sample piece of nonwoven fabric, the thickness (initial thickness) of the nonwoven fabric under a load of 40 Pa was measured in the same manner as the method described above. Next, after leaving the same sample piece under a load of 1.63 kPa for 3 days, the thickness (final thickness) of the nonwoven fabric under a load of 40 Pa was measured again in the same manner as the method described above after removing the load of 1.63 kPa. The thickness reduction rate (%) was determined according to the following formula. Thickness reduction rate (%) = [(Initial thickness - Final thickness) / Initial thickness] × 100

[0093] <Stiffness-flexibility> The stiffness-flexibility of the nonwoven fabric was measured according to JIS L 1096:2010 8.21.5 Method E (Handle Odometer Method). Specifically, it was measured by the following procedure. A test piece with a length of 20 cm and a width of 20 cm was placed on the sample stage so that the measurement direction of the test piece was perpendicular to the slot (gap width 10 mm). Next, the blade of the penetrator adjusted to descend 8 mm from the surface of the sample stage was lowered to press the test piece. When pressing, at a position 6.7 cm (1 / 3 of the width of the test piece) from either side, for different front and back positions in the longitudinal and transverse directions respectively, the resistance value against the pressing was read. As the resistance value, the highest value indicated by the microammeter was read. The sum of the highest values of the four sides was obtained, and the average value of the sum three times was calculated to obtain the stiffness-flexibility (g) of the sample. In addition, the value obtained by dividing the above stiffness-flexibility by the thickness (the value obtained by applying a load of 1.96 kPa) was defined as the stiffness-flexibility per unit thickness (stiffness-flexibility / thickness (g / mm)).

[0094] <Tensile strength and elongation> The tensile strength was measured in accordance with JIS L 1096:2010 8.14.1 Method A (strip method). Using a constant-speed tension type tensile testing machine, a tensile test was conducted under the conditions of a sample piece (non-woven fabric) width of 5 cm, a gripping interval of 10 cm, and a tensile speed of 30 ± 2 cm / min. The load value at the time of cutting (breaking strength), elongation at break, stress at 10% elongation, stress at 20% elongation, and stress at 30% elongation were measured. The tensile test was carried out with the longitudinal direction (MD direction) and the transverse direction (CD direction) of the non-woven fabric as the tensile directions. The evaluation results were all shown as the average of the measured values for three samples.

[0095] <Maximum frictional force and dynamic frictional force> The maximum frictional force and dynamic frictional force were measured using a static and dynamic friction measuring machine (TriboMaster TL201Ts, manufactured by Trinity Lab Co., Ltd.). A non-woven fabric of 5 cm × 10 cm was prepared as the sample piece. Note that as the sample pieces, those with the MD direction of the non-woven fabric as the long side and those with the CD direction as the long side were prepared respectively. A tactile contactor (manufactured by Trinity Lab Co., Ltd.) was used for the contact terminals of the measuring instrument. The sample piece was fixed to the measuring machine, and the contact terminal was moved back and forth twice on the surface of the sample piece at a load of 30 g, a speed of 10 mm / sec, and a distance of 30 mm for evaluation. For the examples and comparative examples processed by a hot air penetration type heat treatment machine, the contact terminal was brought into contact with the surface opposite to the surface where the hot air was applied for measurement. The numerical value of the second round trip was read, and the average value of the numerical value of the forward and the return was taken as the maximum frictional force (gf) and dynamic frictional force (gf) of one sample piece. The measurement was carried out three times for the test piece with the MD direction as the long side and three times for the test piece with the CD direction as the long side. The average value of the total six measurement values was taken as the maximum frictional force Fs (gf) and dynamic frictional force Fk (gf) of each example and comparative example. Also, from the standard deviation σ (gf) of the dynamic frictional force obtained during the measurement and the average value Fk of the above-mentioned dynamic frictional force, the coefficient of variation CV of the dynamic frictional force was obtained according to the following formula. Coefficient of variation CV of dynamic frictional force = σ / Fk

[0096] <Water retention rate> The nonwoven fabric was cut into 100 mm × 100 mm in the MD direction × CD direction, and the mass of the nonwoven fabric was measured. Then, the nonwoven fabric was immersed in test distilled water (2 drops of dishwashing detergent (Joy Fresh Orange Scent (containing 33% surfactant), manufactured by Procter & Gamble Co., Ltd.) was added to 1 liter of distilled water) for 2 minutes. Three corners of the nonwoven fabric impregnated with the test distilled water were clamped with laundry clothespins and hung. After 10 minutes, the mass of the nonwoven fabric (including water) was measured. The water retention rate of the nonwoven fabric was calculated according to the following formula. Water retention rate (%) = [(M2 - M1) / M1] × 100 M1: Mass of the nonwoven fabric before immersion in the test distilled water (g) M2: Mass of the nonwoven fabric after hanging the nonwoven fabric immersed in the test distilled water for 10 minutes (g)

[0097] <Lint evaluation> The surface of a disk (diameter 70 mm, 350 g) was covered with a urethane foam having a thickness of 0.5 mm. The disk was attached to a rotating shaft at a position where the center of the disk was displaced by 20 mm from the rotating shaft. The nonwoven fabric with the urethane foam laid thereon was fixed on a table. The above disk was placed on the nonwoven fabric, and the rotating shaft was rotated to move the disk in a circular motion on the nonwoven fabric. The circular motion was performed 2 times clockwise and 2 times counterclockwise. The circular motion speed at this time was about 3 seconds per revolution. Regarding the nonwoven fabric after the circular motion, the lint state was evaluated according to the following criteria. 3 to 5 is considered that the lint is suppressed. 5: Very good (no lint) 4: Good (very little lint) 3: Normal (lint is not bothersome) 2: Bad (lint is bothersome) 1: Very bad (a lot of lint)

[0098] <Lint evaluation 2> Evaluation was performed by an abrasion test using a Martindale lint tester (manufactured by James Heal Co., Ltd., product name "Martindale Abrasion and Pilling Tester No. 1309"). For the nonwovens of the examples and comparative examples, two samples (one with a diameter of 140 mm and one with a diameter of 38 mm) were prepared. A felt with a diameter of 140 mm was placed on the Abrading Table, and the sample with a diameter of 140 mm was laminated on the SM25 Abrasice Cloth and fixed with a Clamp Ring. Next, a sample with a diameter of 38 mm and a polyurethane with a diameter of 38 mm were placed in the Sample Holder. The measurement conditions were that the Sample Holder was placed on the Abrading Tables without installing a Loading Weight on the Sample Holder. The number of friction rotations was set to 8 rotations, and the motion was set to 60.5 mm Lissajous, and a friction test was performed. For the examples and comparative examples processed by a hot air penetration type heat treatment machine, the friction test was performed so that the surfaces on the side opposite to the side where the hot air was applied came into contact with each other. After the measurement, the nonwoven fabric on the Sample Holder side was observed, and the fuzz state was evaluated on a total scale of 10 points based on the following two criteria (the state when the nonwoven fabric after measurement was viewed from directly above (surface state) and the state when the nonwoven fabric after measurement was viewed from the side (degree of fuzzing)). A total of 6 points or more was considered to have the fuzz suppressed. For each example or comparative example, the evaluation test was performed 3 times, and the average value of the scores of the 3 times was used as the fuzz evaluation of each example or comparative example. Surface state 5: Very good (no surface disturbance) 4: Good (very little surface disturbance) 3: Normal (little surface disturbance, not noticeable) 2: Bad (surface disturbance is noticeable) 1: Very bad (holes on the surface) Degree of fuzzing 5: Very good (no fuzzing) 4: Good (very little fuzzing) 3: Normal (fuzzing is not noticeable) 2: Bad (fuzzing is noticeable) 1: Very bad (a lot of fuzzing) Regarding fluff, there are two evaluation methods: <fluff evaluation> and <fluff evaluation 2>. For <fluff evaluation>, if it is 3 or more, it is considered qualified. For <fluff evaluation 2>, if the total is 6 or more, it is considered qualified. Furthermore, if either <fluff evaluation> or <fluff evaluation 2> is qualified, the fluff is considered qualified. If both <fluff evaluation> and <fluff evaluation 2> are qualified, it is more preferable for the fluff.

[0099]

Table 1

[0100]

Table 2

[0101]

Table 3

[0102] The nonwoven fabrics of Examples 11 to 43 and 81 to 86 all contain cellulose fibers and adhesive fibers, include the adhesion sites between the adhesive fibers and the cellulose fibers and / or adhesive fibers, and include the entanglement sites between the cellulose fibers and the cellulose fibers and / or adhesive fibers. Furthermore, the nonwoven fabrics of Examples 11 to 43 and 81 to 86 all have (i) the adhesion intersection index A of the nonwoven fabric being 1 to 60 pieces / mm 2It has the characteristics that (i) is such-and-such, and / or (ii) the thickness reduction rate of the non-woven fabric is 30 - 45%.

[0103] The non-woven fabrics of Examples 11 - 43 and 81 - 86 include both the adhesion parts and the entanglement parts, so the suppression of fluff is good. Furthermore, in the non-woven fabrics of Examples 11 - 43 and 81 - 86, either (i) or (ii) above shows the above specific values, so the texture is soft and good. Therefore, the non-woven fabrics of Examples 11 - 43 and 81 - 86 show excellent properties of good fluff suppression and texture.

[0104] On the contrary, the non-woven fabrics of Comparative Examples 50 - 72 are never good in fluff suppression and texture. For example, Comparative Examples 50 - 62 have only either the adhesion part or the entanglement part. Therefore, the fluff suppression is insufficient. Comparative Examples 71 - 72 have both the adhesion part and the entanglement part, so the fluff suppression is good, but since either (i) or (ii) does not show the above specific values, the texture is hard and insufficient.

[0105] When checking the stiffness and softness per unit thickness of the non-woven fabric, compared with the non-woven fabrics of Examples 11 - 43 and 81 - 86, the values of the non-woven fabrics of Comparative Examples 71 and 72 are larger, and the non-woven fabrics of the examples are softer and better in texture.

[0106] Regarding the thickness ratio of the non-woven fabric, when comparing Examples 31 - 33 with the same mixing ratio and Comparative Examples 71 - 72, the values of the non-woven fabrics of the comparative examples are larger than those of the non-woven fabrics of the examples, and the non-woven fabrics of the examples are softer and better in texture. Also, when comparing Examples 31 - 33 with the same mixing ratio and Comparative Example 50, the values of the non-woven fabrics of the comparative examples are smaller than those of the non-woven fabrics of the examples, and the non-woven fabrics of the examples are less likely to sag.

[0107] Regarding the angle of the fiber adhesion points in the middle when the nonwoven fabric is divided into three equal parts in the thickness direction, when comparing Example 31 with the same mixing ratio, Comparative Example 50, and Comparative Example 71, the value of the nonwoven fabric of Comparative Example 71 is smaller than that of the nonwoven fabric of Example 31, and the nonwoven fabric of the example is softer and better in texture. Also, the value of the nonwoven fabric of Comparative Example 50 is larger than that of the nonwoven fabric of Example 31, and the nonwoven fabric of the example is less likely to sag. Moreover, in Example 84 where mechanically crimped fibers were used as the adhesive fibers, since the value of the angle was small, it is considered that adhesive fibers with three-dimensional crimp can make the texture softer.

[0108] Regarding the coefficient of variation of the dynamic friction force of the nonwoven fabric, when comparing Examples 11, 21, 31, and 41 with the same water pressure and Comparative Example 71, the value of the nonwoven fabric of the example is smaller than that of the nonwoven fabric of the comparative example, and the surface of the nonwoven fabric of the example is smoother. Also, for Examples 12, 22, 32, and 42 with the same water pressure and Comparative Example 72, similarly, the surface of the nonwoven fabric of the example is smoother. It is speculated that by performing the adhesion process before the entanglement process, the entanglement of the fibers becomes appropriate and the surface of the nonwoven fabric can be made smooth. In particular, since the fiber webs of the examples and comparative examples were produced by a parallel carding machine, the fibers are relatively oriented in the MD direction. By performing the adhesion process before the entanglement process, it is speculated that the fiber orientation is relatively maintained and the surface of the nonwoven fabric becomes smoother.

[0109] Regarding the nonwoven fabric of Example 31, the nonwoven fabric was cut in the transverse direction (more specifically, the direction perpendicular to the traveling direction of the belt conveyors of the heat treatment machine and the water flow treatment machine that processed the nonwoven fabric), and the cut surface was observed with a scanning electron microscope (SEM, magnification: 100 times). Figure 3 is an enlarged cut part near the middle (inside) of the nonwoven fabric when the nonwoven fabric is divided into three equal parts in the thickness direction. It can be seen that in the nonwoven fabric of Example 31, in the interior of the nonwoven fabric, adhesive peeling marks where the adhesion points by the adhesive fibers have disappeared are formed on the adhesive fibers. Regarding the nonwoven fabric of Example 31, the front and back surfaces of the nonwoven fabric were observed with a scanning electron microscope (SEM, magnification: 100 times). Fig. 4 shows the observation of the front surface of the nonwoven fabric, and it can be seen that in the nonwoven fabric of Example 31, adhesive peeling marks where the adhesion points by the adhesive fibers have disappeared are formed on the adhesive fibers on the front surface of the nonwoven fabric. Also, Fig. 5 shows the observation of the back surface of the nonwoven fabric, and it can be seen that in the nonwoven fabric of Example 31, adhesive peeling marks where the adhesion points by the adhesive fibers have disappeared are formed on the adhesive fibers on the back surface of the nonwoven fabric.

[0110] When comparing Example 31 using lyocell and Example 85 using cotton with different cellulose-based fibers, Example 31 using lyocell had a higher breaking strength and higher stress at 10%, 20%, and 30% elongation in the MD direction than Example 85 using cotton. Also, the hairiness evaluation of Example 31 was higher. It is presumed that since the variation in fineness and fiber length of lyocell is extremely small, the nonwoven fabric strength and hairiness became relatively good.

[0111] When comparing Example 31 using lyocell and Example 86 using water-repellent rayon with different cellulose-based fibers, Example 31 using lyocell had a higher breaking strength and higher stress at 10%, 20%, and 30% elongation than Example 86 using water-repellent rayon. Also, the hairiness evaluation of Example 31 was higher. Since the entanglement by columnar water flow of lyocell with a sedimentation rate of about 4 seconds is relatively stronger than that of water-repellent rayon, it is presumed that the nonwoven fabric strength and hairiness became relatively good. On the other hand, Example 86 had lower maximum frictional force and dynamic frictional force than Example 31, and the slipperiness of the nonwoven fabric surface was relatively good.

[0112] When comparing Example 31 and Example 84 with different sheath components of the adhesive fibers, Example 84 had higher stress at 10%, 20%, and 30% elongation in the MD direction in all cases. It is presumed that the strength of the nonwoven fabric is improved by using a resin with high adhesiveness to cellulose-based fibers such as ethylene-acrylic acid copolymer as the sheath component.

[0113] When comparing Example 82 and Example 83, which have slightly different manufacturing methods for non-woven fabrics in the laminated structure, the evaluation of the hairiness was better in Example 83. The layer to which hot air is applied tends to have a lower fiber density than the layer on the opposite side (the layer in contact with the support), and the entanglement by the columnar water flow progresses relatively. On the other hand, since the entanglement hardly progresses in the layer on the opposite side, it is presumed that when the content of the cellulose-based fiber is large in the layer on the opposite side, the entanglement occurs relatively strongly and the hairiness is less likely to occur.

[0114] The present disclosure includes the following aspects. (Aspect 1) A non-woven fabric containing a cellulose-based fiber and an adhesive fiber, including an adhesion portion between the adhesive fiber and the cellulose-based fiber and / or the adhesive fiber, including an entanglement portion between the cellulose-based fiber and the cellulose-based fiber and / or the adhesive fiber, wherein the adhesion intersection index A of the non-woven fabric is 1 to 60 pieces / mm 2 is, non-woven fabric. (Aspect 2) A non-woven fabric containing a cellulose-based fiber and an adhesive fiber, including an adhesion portion between the adhesive fiber and the cellulose-based fiber and / or the adhesive fiber, including an entanglement portion between the cellulose-based fiber and the cellulose-based fiber and / or the adhesive fiber, wherein the thickness reduction rate of the non-woven fabric is 30 to 45%, non-woven fabric. (Aspect 3) The non-woven fabric according to any one of Aspect 1 or 2, wherein the cellulose-based fiber is contained in an amount of 25 to 75% by mass. (Aspect 4) A method for manufacturing a non-woven fabric containing a cellulose-based fiber and an adhesive fiber, the method including an adhesion step of adhering fibers to each other with the adhesive fiber and an entanglement step of entangling the fibers after the adhesion step. (Aspect 5) The method for manufacturing a non-woven fabric according to Aspect 4, including a cooling step between the adhesion step and the entanglement step. (Aspect 6) The method for manufacturing a nonwoven fabric according to aspect 4 or 5, wherein the entanglement step includes a water flow entanglement treatment. (Aspect 7) The method for manufacturing a nonwoven fabric according to aspect 6, wherein the adhesion step includes a hot air processing treatment, and in the water flow entanglement step, a columnar water flow is injected first from the side where hot air is blown. (Aspect 8) The method for manufacturing a nonwoven fabric according to aspect 6 or 7, including a drying step after the water flow entanglement treatment, and the temperature of the drying step is 10°C or more lower than the temperature at which the adhesive component of the adhesive fiber softens or melts. (Aspect 9) Including a drying step after the water flow entanglement treatment, The adhesive fiber includes two or more adhesive fibers having different melting points or softening points of the adhesive component, The method for manufacturing a nonwoven fabric according to aspect 6 or 7, wherein the melting point or softening point T1 (°C) of the heat adhesive component having a higher melting point or softening point, the melting point or softening point T2 (°C) of the heat adhesive component having a lower melting point or softening point, and the temperature T (°C) of the drying treatment satisfy the relationship of T2 ≤ T < T1.

Industrial Applicability

[0115] The nonwoven fabric of the present disclosure alleviates, preferably solves, at least one of the problems such as insufficient suppression of fluff and a hard texture, and can be used for applications that directly touch human skin, such as absorbent articles. Related Applications Note that this application claims priority based on Article 4 of the Paris Convention based on Application No. 2018-018501 filed in Japan on February 5, 2018. The content of this basic application is incorporated herein by reference.

Claims

1. A nonwoven fabric containing a cellulose-based fiber and an adhesive fiber, including an adhesion point between the adhesive fiber and the cellulose-based fiber and / or the adhesive fiber, including an entanglement point between the cellulose-based fiber and the cellulose-based fiber and / or the adhesive fiber, The adhesion intersection index A of the nonwoven fabric is 1 to 60 pieces / mm ２ and wherein the fiber length of the cellulose-based fiber is 25 to 100 mm, the fiber length of the adhesive fiber is 25 to 100 mm, including an adhesive fiber that forms an adhesive peel mark where the adhesion point by the adhesive fiber is eliminated, a nonwoven fabric. <Adhesion intersection index A> Here, the adhesion intersection index A is obtained as follows. Observe the front and back surfaces of the nonwoven fabric with a scanning electron microscope (SEM, acceleration voltage: 10.0 kV, magnification: 100 times). For the taken SEM image, count the number of fiber adhesion intersections per unit area. For three sheets each of the front and back surfaces of the nonwoven fabric, count the number of fiber adhesion intersections for a total of six SEM images, and take the average value as the number of fiber adhesion intersections I (unit: pieces / mm²). From the fineness (dtex) and mixing ratio (mass%) of the non-adhesive fiber (cellulose-based fiber: fiber 1) and the adhesive fiber (fiber 2) constituting the nonwoven fabric, obtain the adhesion intersection ratio P (0 ≤ P ≤ 1) according to the following formula. 【Number 1】 In the formula, αi represents the mixing ratio (mass%) of the i-th non-adhesive fiber, xi represents the fineness (dtex) of the i-th non-adhesive fiber, βj represents the mixing ratio (mass%) of the j-th adhesive fiber, yj represents the fineness (dtex) of the j-th adhesive fiber. From the number of adhesion intersections I and the adhesion intersection ratio P, obtain the adhesion intersection index A (unit: pieces / mm²) according to the following formula. Adhesion intersection index A = I / (P²)

2. The nonwoven fabric according to claim 1, wherein the cellulose-based fiber is contained in an amount of 25 to 75% by mass.

3. The nonwoven fabric according to claim 1 or 2, wherein the thickness ratio of the nonwoven fabric is 0.25 to 0.

69. Here, the "thickness ratio" of the nonwoven fabric is obtained as follows. Using a thickness measuring machine (THICKNESS GAUGE model CR-60A (trade name) manufactured by Dai-ichi Kagaku Seiki Co., Ltd.), measure the thickness of the nonwoven fabric with a load of 1.96 kPa applied. On the other hand, using a CCD laser displacement meter (amplifier unit type: LK-2100, sensor head type: LK-080, manufactured by Keyence Corporation), measure the thickness of the nonwoven fabric with a load of 40 Pa applied. The "thickness ratio" of the nonwoven fabric is determined as the ratio of the thickness obtained by applying a load of 1.96 kPa to the thickness obtained by applying a load of 40 Pa (thickness obtained by applying a load of 1.96 kPa / thickness obtained by applying a load of 40 Pa).

4. The nonwoven fabric according to any one of claims 1 to 3, wherein the fiber density on at least one surface is higher than the internal fiber density.

5. A method for manufacturing a nonwoven fabric comprising a cellulosic fiber and an adhesive fiber, wherein the nonwoven fabric includes adhesion points between the adhesive fiber and the cellulosic fiber and / or the adhesive fiber, the nonwoven fabric includes entanglement points between the cellulosic fiber and the cellulosic fiber and / or the adhesive fiber, The adhesion intersection index A of the non-woven fabric is 1 to 60 pieces / mm ２ and the manufacturing method includes a step of mixing the cellulosic fiber and the adhesive fiber to produce a fiber web which is a card web, an adhesion step of adhering the fibers with the adhesive fiber, and an entanglement step of entangling the fibers after the adhesion step, the adhesion step includes a hot air processing treatment, the entanglement step includes a water stream entanglement treatment, and the water stream entanglement treatment includes spraying a columnar water stream first from the side where hot air is blown, A method for manufacturing a nonwoven fabric. <Adhesion intersection index A> Here, the adhesion intersection index A is determined as follows. The front and back surfaces of the nonwoven fabric are observed with a scanning electron microscope (SEM, acceleration voltage: 10.0 kV, magnification: 100 times). For the taken SEM images, the number of fiber adhesion intersections per unit area is counted. For three SEM images each of the front and back surfaces of the nonwoven fabric, a total of six SEM images, the number of fiber adhesion intersections is counted, and the average value is taken as the number of fiber adhesion intersections I (unit: pieces / mm 2). From the fineness (dtex) of the non-adhesive fibers (cellulosic fibers: fiber 1) and the adhesive fibers (fiber 2) constituting the nonwoven fabric and the mixing ratio (mass%) in the nonwoven fabric, the adhesion intersection ratio P (0 ≤ P ≤ 1) is determined according to the following formula. 【Number 2】 In the formula, α i represents the mixing ratio (mass%) of the i-th non-adhesive fiber, x i represents the fineness (dtex) of the i-th non-adhesive fiber, β j represents the mixing ratio (mass%) of the j-th adhesive fiber, y j represents the fineness (dtex) of the j-th adhesive fiber. From the number of adhesion intersections I and the adhesion intersection ratio P, the adhesion intersection index A (unit: pieces / mm 2) is determined according to the following formula. Adhesion intersection index A = I / (P 2)

6. The method for manufacturing a nonwoven fabric according to claim 5, including a cooling step between the adhesion step and the entanglement step.

7. The method for manufacturing a nonwoven fabric according to claim 5 or 6, including a drying step after the water stream entanglement treatment, wherein the temperature of the drying step is at least 10°C lower than the temperature at which the adhesive component of the adhesive fiber softens or melts.

8. including a drying step after the water stream entanglement treatment, the adhesive fiber includes two or more adhesive fibers having different melting points or softening points of the adhesive component, The melting point or softening point T of the adhesive component having a higher melting point or softening point １ (°C), the melting point or softening point T of the adhesive component having a lower melting point or softening point ２ (°C), and the temperature T (°C) of the drying treatment satisfy T ２ ≦ T < T １ The method for manufacturing a nonwoven fabric according to claim 5 or 6, which satisfies the relationship of.

9. The method for manufacturing a nonwoven fabric according to any one of claims 5 to 8, wherein the fiber density on at least one surface is higher than the internal fiber density.

10. The method for manufacturing a nonwoven fabric according to any one of claims 5 to 9, including an adhesive fiber that forms an adhesive peeling mark where the adhesive part by the adhesive fiber has been eliminated.

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