Nonwoven fabric and method for producing same, and wiper

Abstract

Provided are nonwoven fabric and a wiper which are excellent in washing durability. This nonwoven fabric has a binding site for a binder, wherein the ratio (bias stress / basis weight) of a bias stress (N / 5 cm) at 20% elongation in a bias direction of the nonwoven fabric in a saturated moisture state and in a 300% wet state to a basis weight (g / m2) of the nonwoven fabric with an official moisture content is 0.15 or more.

Description

Nonwoven fabric, manufacturing method thereof, and wiper

[0001] The present invention relates to a nonwoven fabric having excellent washing durability, a method for producing the same, and a wiper.

[0002] In recent years, the applications of nonwoven fabrics have expanded to include household goods, hygiene, medical, etc. Nonwoven fabrics are sometimes used as disposable products, but from economic and environmental perspectives, when they are used as wipers such as office dishcloths and industrial wipers, there is a demand for nonwoven fabrics that can be washed and reused.

[0003] For example, Patent Document 1 (JP 2008-115476 A) describes a fabric having a basis weight of 30 to 100 g / m formed from a fiber web containing at least rayon fibers and additionally containing synthetic fibers. ２ The document discloses a mesh-like nonwoven fabric characterized in that an acrylic resin is applied twice to the front and back surfaces of the fiber web.

[0004] Patent Document 2 (JP 2008-213194 A) describes a nonwoven fabric sheet for cleaning, which has binder layers on the front and back surfaces of a nonwoven fabric sheet, and the nonwoven fabric sheet has an opening area of ​​2.0 to 4.0 mm 2 a through-hole row pattern in which a plurality of through-holes are arranged alternately vertically and horizontally, the distance between adjacent through-holes in the through-hole row pattern being 2.0 to 4.0 mm; the binder layer is comprised of two or more layers, at least one of which is formed over the entire front and back surfaces of the nonwoven fabric sheet; and the binder layer located on the top front and back surface layers is composed of wavy lines arranged in parallel at equal intervals, forming a wavy pattern in plan view.

[0005] Patent Document 3 (WO 2019 / 208160) discloses a nonwoven fabric having an adhesive region of a binder, in which a cut surface in the thickness direction randomly selected from the adhesive region of the nonwoven fabric is divided into three equal parts in the thickness direction, each of which is an upper layer part, a lower layer part, and a middle layer part of the nonwoven fabric, and each part has a plurality of fiber bundles in which a plurality of single fibers are bound and integrated by the binder, and the total number of single fibers present in the fiber bundles satisfies Nu / Nc > 1.10 and Nb / Nc > 1.10, where Nu is the total number of fibers in the bundles in the upper layer part, Nb is the total number of fibers in the bundles in the lower layer part, and Nc is the total number of fibers in the bundles in the middle layer part, respectively.

[0006] JP 2008-115476 A JP 2008-213194 A International Publication No. 2019 / 208160

[0007] Patent Documents 1 and 2 state that the nonwoven fabrics have washing durability, but the washing durability is evaluated merely by the fiber elongation rate after one cycle using an electric bucket without a spin-drying function. In Patent Document 3, washing durability is evaluated using a washing machine with a spin-drying function, but washing durability is evaluated merely by the fiber shape after five cycles.

[0008] Therefore, an object of the present invention is to provide a nonwoven fabric and a wiper that have dramatically improved washing durability compared to conventional nonwoven fabrics and wipers.

[0009] As a result of extensive research to achieve the above-mentioned object, the inventors of the present invention have found that, during washing, laundry is subjected to stress in the washing and rinsing steps when the laundry is saturated with moisture, and also in the spin-drying step in which moisture is released from the saturated moisture state by centrifugal action; therefore, when evaluating the washing durability of a nonwoven fabric, it is important to evaluate the nonwoven fabric in a state in which a certain amount of moisture is present, rather than in a dry state at the time of the process moisture; and further, that in the washing and rinsing steps and the spin-drying step, the nonwoven fabric is subjected to particularly strong stress in the bias direction. The inventors then focused on the stress (bias stress) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture, which corresponds to the washing and rinsing steps, and / or the bias stress of a nonwoven fabric when 300% wet, which represents the state in which the nonwoven fabric is subjected to centrifugal force in the spin-drying step, and discovered that the washing durability of water-absorbent nonwoven fabrics can be dramatically improved if the stress at 20% elongation in the bias direction of the nonwoven fabric per unit basis weight, standardized by the basis weight of the nonwoven fabric, can be increased, i.e., if the ratio of the stress (bias stress) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet, to the basis weight of the nonwoven fabric (bias stress / basis weight) can be increased, which led to the completion of the present invention.

[0010] That is, the present invention can be configured in the following aspects: [Aspect 1] A nonwoven fabric having a binder attachment site, wherein the bias stress (N / 5 cm) at 20% elongation in the bias direction of the nonwoven fabric when saturated with moisture and / or 300% wet, and the basis weight (g / m) of the nonwoven fabric at the standard moisture content are ２ A nonwoven fabric according to Aspect 1, wherein the ratio (bias stress / basis weight) of the bias stress (N / 5 cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet to the basis weight (g / m) of the nonwoven fabric at the standard moisture content is 0.15 or more (preferably 0.16 or more, more preferably 0.17 or more, and even more preferably 0.19 or more). ２A nonwoven fabric having a ratio (bias stress / basis weight) of 0.35 or more to the breaking strength (N / 5cm) in the machine direction (hereinafter referred to as MD) of the nonwoven fabric at the standard moisture content to the breaking strength (N / 5cm) in the direction perpendicular to the MD (hereinafter referred to as CD) (MD breaking strength / CD breaking strength) of 0.6 or more and less than 3.0 (preferably 0.6 to 2.9, more preferably 0.6 to 1.5). A nonwoven fabric having a ratio (MD breaking strength / CD breaking strength) of 0.6 or more to less than 3.0 (preferably 0.6 to 2.9, more preferably 0.6 to 1.5) to the breaking strength (N / 5cm) in the direction perpendicular to the MD of the nonwoven fabric at the standard moisture content of the nonwoven fabric (preferably 30 N / 5cm or more, more preferably 35 N / 5cm or more, and particularly preferably 45 N / 5cm or more). A nonwoven fabric having a ratio (MD breaking strength / CD breaking strength) of 0.6 or more to less than 3.0 (preferably 0.6 to 2.9, more preferably 0.6 to 1.5) to the breaking strength (N / 5cm) in the machine direction (hereinafter referred to as MD) of the nonwoven fabric at the standard moisture content of the nonwoven fabric (preferably 0.6 to 2.9, more preferably 0.6 to 1.5). A nonwoven fabric having a ratio (MD breaking strength / CD breaking strength) of 25 N / 5cm or more to the breaking strength (N / 5cm) in the machine direction (hereinafter referred to as MD) of the nonwoven fabric at the standard moisture content of the nonwoven fabric (preferably 30 N / 5cm or more, more preferably 35 N / 5cm or more, and particularly preferably 45 N / 5cm or more). [Aspect 5] The nonwoven fabric according to any one of Aspects 1 to 4, wherein the binder adhesion rate is 2 to 50 mass% (preferably 3 to 40 mass%, more preferably 4 to 30 mass%, and particularly preferably 5 to 20 mass%). [Aspect 6] The nonwoven fabric according to any one of Aspects 1 to 5, wherein the nonwoven fabric has a fiber arrangement structure derived from a cross web. [Aspect 7] The nonwoven fabric according to any one of Aspects 1 to 6, wherein the basis weight is 30 to 250 g / m ２ (preferably 35 to 200 g / m ２ More preferably, 40 to 150 g / m ２Aspect 8: The nonwoven fabric according to any one of Aspects 1 to 7, wherein the ratio of the stress (N / 5 cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet to the average breaking strength (N / 5 cm) in MD and CD when the nonwoven fabric is 300% wet (bias stress / average breaking strength) is 0.10 to 1.00 (preferably 0.13 to 0.95, more preferably 0.15 to 0.90, and even more preferably 0.18 to 0.90). [Aspect 9] The nonwoven fabric according to any one of Aspects 1 to 8, wherein when a 200% wet nonwoven fabric (longer side 30 cm x shorter side 5 cm) is placed on a horizontal surface with either the MD or CD of the nonwoven fabric being the longer side, and one shorter side is lifted and laid over the other shorter side to form a curved shape of the nonwoven fabric, and the distance from the horizontal surface to the maximum height of the curved shape in the MD is 30 mm or less (preferably 25 mm or less, more preferably 22 mm or less) and / or 30 mm or less (preferably 25 mm or less, more preferably 20 mm or less) in the CD. [Aspect 10] The nonwoven fabric according to any one of Aspects 1 to 9, wherein the nonwoven fabric contains 50 mass % or more (preferably 60 mass % or more, more preferably 70 mass % or more) of hydrophilic fibers. [Aspect 11] The nonwoven fabric according to any one of Aspects 1 to 10, wherein the binder is present continuously on both the front and back surfaces of the nonwoven fabric. [Aspect 12] The nonwoven fabric according to any one of Aspects 1 to 11, wherein the nonwoven fabric has a plurality of apertures, and the colored binder forms a continuous wave pattern in the CD of the nonwoven fabric, and the wave pattern is present in multiple rows at approximately equal intervals in the MD of the nonwoven fabric. [Aspect 13] The nonwoven fabric according to any one of Aspects 1 to 12, wherein the water retention is 400% or more (preferably about 500% or more, more preferably 600% or more). [Aspect 14] A wiper made of the nonwoven fabric according to any one of Aspects 1 to 13.[Aspect 15] A method for producing a nonwoven fabric, comprising the steps of: subjecting a web having at least a cross-web structure to an entanglement treatment with a high-pressure water stream having a water pressure of 5 MPa or more to obtain a raw nonwoven fabric; and applying a binder liquid to the raw nonwoven fabric by dip nip or coating. [Aspect 16] The method for producing a nonwoven fabric of Aspect 15, further comprising the step of drying the raw nonwoven fabric to which the binder liquid has been applied by alternately contacting it with a plurality of heated rolls using a cylinder dryer. [Aspect 17] The method for producing a nonwoven fabric of Aspect 15 or 16, wherein the temperature of the water stream in the entanglement treatment is 35°C or more (preferably 40°C or more).

[0011] Here, the bias direction means a direction that is 45° clockwise with respect to the machine direction (hereinafter referred to as MD) and the direction perpendicular to the MD (hereinafter referred to as CD) at the standard moisture content of the nonwoven fabric, and 45° counterclockwise with respect to the MD.

[0012] The term "at saturated moisture content" refers to a state in which the nonwoven fabric is placed in a container, water is poured into the container, the nonwoven fabric is left completely immersed in water for 60 minutes, and then the nonwoven fabric is removed from the container without squeezing out the water.

[0013] "300% wet" refers to the state in which the nonwoven fabric is allowed to absorb water three times the mass of the nonwoven fabric at its official moisture content, and is left for 15 minutes until the water has penetrated evenly into the nonwoven fabric.

[0014] The term "standard moisture content" refers to the state in which the nonwoven fabric is placed under standard conditions (20±2°C, relative humidity 65±2%) and the mass of the nonwoven fabric becomes constant.

[0015] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms "at least one," unless the content clearly dictates otherwise. As used herein, the terms "and / or," "at least one," and "one or more" include any and all combinations of the associated listed items.

[0016] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention, and in particular any combination of two or more of the claims set forth in the claims is included in the present invention.

[0017] The present invention can dramatically improve the washing durability of the water-absorbent nonwoven fabric, and therefore the water-absorbent nonwoven fabric can be reused by washing it in a washing machine as usual, and can be suitably used as, for example, industrial wipers, cleaning cloths for business use, or other wipers that can be washed and reused.

[0018] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and explanation purposes only and should not be used to define the scope of the present invention, which is defined by the appended claims.

[0019] 1 is a schematic plan view illustrating a substantially linear adhesion site; FIG. 2 is a schematic plan view illustrating a wave-shaped adhesion site; FIG. 3 is a schematic perspective view of a nonwoven fabric of one embodiment illustrating a method for measuring the maximum height of a curved shape at approximately the center portion formed by overlapping two halves of a nonwoven fabric; FIG. 4 is a schematic plan view illustrating a process for drying a binder-coated raw nonwoven fabric; FIG. 5 is a schematic plan view illustrating a method for measuring the side lengths of a nonwoven fabric sample before washing; FIG. 6 is a schematic plan view illustrating a measuring plate used for measuring the dimensional change rate of a nonwoven fabric sample after washing; FIG. 7 is a schematic plan view illustrating a measuring method for placing a nonwoven fabric sample after 30 washes on the measuring plate and subtracting the amount of shrinkage relative to the measuring plate; FIG. 8 is a schematic plan view illustrating a measuring method for placing a nonwoven fabric sample after 30 washes on the measuring plate and adding the amount of expansion relative to the measuring plate; FIG. 9 is a photograph of the nonwoven fabric obtained in Example 1 after washing; FIG. 10 is a photograph of the nonwoven fabric obtained in Comparative Example 3 after washing.

[0020] The nonwoven fabric of the present invention is a water-absorbent nonwoven fabric having an adhesive surface formed by a binder, and is characterized by a bias stress (N / 5cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet, and a basis weight (g / m) of the nonwoven fabric at the standard moisture content. ２ The ratio of the bias stress to the basis weight (bias stress / basis weight) is 0.15 or more. The characteristics of the nonwoven fabric will be described below.

[0021] A nonwoven fabric of one embodiment has a binder (glue or adhesive agent) attachment site. Here, the binder attachment site refers to a site where the binder is applied to the constituent fibers of the nonwoven fabric, and typically refers to a portion where the binder attached to the fibers can be confirmed when the surface of the nonwoven fabric is visually observed. The nonwoven fabric of the present invention may also have a binder attachment site in part and a non-attached site. Here, the non-attached site refers to a portion where the binder adhesion cannot be confirmed when the surface of the nonwoven fabric is visually observed. Note that, when the nonwoven fabric has a mesh structure, the open pores of the mesh structure are not included in the non-attached site.

[0022] Here, adhesion of the binder to the fiber can be determined by the colored binder if the binder is colored, or by dyeing the binder using a dyeing method if the binder is transparent.

[0023] In one embodiment, the nonwoven fabric preferably has binder attachment sites that are continuous from one end to the other end on at least one surface of the nonwoven fabric, preferably on both the front and back surfaces of the nonwoven fabric. When the binder attachment sites are continuous from one end to the other end, for example, the binder may form planar attachment sites or linear attachment sites without interruption from one end to the other end in the MD or CD of the nonwoven fabric. When the binder attachment sites are continuous from one end to the other end on at least one surface of the nonwoven fabric, the binder can efficiently bind the constituent fibers of the nonwoven fabric.

[0024] The linear attachment sites may have various shapes depending on the line width. The linear attachment sites may have a shape in which the lines do not intersect with each other, or may have a shape in which the lines intersect with each other at least in part. Such shapes may include stripes (for example, straight or curved stripes), a lattice pattern, etc.

[0025] In addition, when the lines intersect with each other at least in part, it is possible to focus on a specific line from the perspective of shortening the distance from one end to the other end, and to grasp the shape of the linear attachment site for that line, in which case the line may share an intersection with other lines.

[0026] For example, Figures 1 and 2 show schematic diagrams illustrating linear attachment sites. As shown in Figure 1, for example, for a linear attachment site arbitrarily selected on at least one surface of a nonwoven fabric, the ratio (L1 / L2) of the distance L1 between the top and bottom of the line to the line width L2 may be, for example, 1 or more, preferably 1.5 or more, and may be, for example, 10 or less, preferably 8 or less. From the viewpoint of improving fiber fixation, L1 / L2 is preferably 1.5 or more. Here, L1 represents the distance between the top and bottom measured within a range of 15 cm from one end of the linear attachment site, and L2 represents the average line width measured five times every 2 cm within that range. The line width represents the width of the line in a direction perpendicular to the longitudinal direction of the line.

[0027] For example, as shown in Figure 1, when the ratio (L1 / L2) of the distance L1 between the top and bottom of the line to the line width L2 is 1 or greater and less than 1.5, the linear attachment site can be considered to be approximately linear, including a straight line of uniform width (L1 / L2 = 1).

[0028] On the other hand, when the ratio (L1 / L2) of the distance L1 between the top and bottom of the line to the line width L2 is 1.5 or more, as shown in Figure 2, the linear attachment portion may form a wavy attachment portion. The wavy shape may have various shapes such as a sine wave, a rectangular wave, a triangular wave, a sawtooth wave, etc., and may be preferably a sine wave.

[0029] The linear attachment sites may form multiple rows, and preferably the multiple rows may be evenly spaced apart from one another.

[0030] Preferably, in the CD, a plurality of linear attachment sites are formed in a plurality of rows without interruption from one end to the other, and in the MD, the plurality of rows may be approximately equally spaced from one another.

[0031] For example, the distance between rows (pitch) may be, for example, 2 to 10 mm, and preferably 3 to 8 mm. Here, the pitch means the distance from the top of one row to the top of the adjacent row, and is indicated by X in FIG. 2, for example.

[0032] The basis weight of the nonwoven fabric of one embodiment is, for example, 30 to 250 g / m from the viewpoint of strength. ２ The thickness may be about 35 to 200 g / m ２ More preferably, 40 to 150 g / m ２ The basis weight is a value measured by the method described in the examples below, and includes the weight of the binder.

[0033] The thickness of the nonwoven fabric of one embodiment can be appropriately determined depending on the application and is not particularly limited, but from the viewpoint of softness, the thickness may be, for example, about 0.1 to 2.0 mm, preferably about 0.2 to 1.5 mm, and more preferably about 0.3 to 1.0 mm. The thickness is a value measured by the method described in the Examples below.

[0034] From the viewpoint of water absorption, the nonwoven fabric of one embodiment may have a water retention rate of, for example, 400% or more, preferably about 500% or more, and more preferably 600% or more. The upper limit is not particularly limited, but may be about 900%. The water retention rate is a value measured by the method described in the Examples below.

[0035] [Wet Characteristics of Nonwoven Fabric] By evaluating a nonwoven fabric based on its wet characteristics, it is possible to effectively evaluate the washing durability of the nonwoven fabric. In one embodiment of the nonwoven fabric, from the viewpoint of enhancing durability against stresses applied during washing, the stress (bias stress) at 20% elongation in the bias direction per unit basis weight, standardized by the basis weight of the nonwoven fabric, falls within a predetermined range in the wet nonwoven fabric. For example, the bias stress (N / 5 cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet, and the basis weight (g / m ２ The ratio (bias stress / basis weight) of the nonwoven fabric to the bias stress (basis stress / basis weight) is 0.15 or more, preferably 0.16 or more, more preferably 0.17 or more, even more preferably 0.19 or more, and particularly preferably 0.35 or more. The upper limit of this ratio is not particularly limited, but from the viewpoint of the softness of the nonwoven fabric, it may be, for example, 0.90 or less, preferably 0.80 or less.

[0036] When the nonwoven fabric of one embodiment is saturated with moisture and / or 300% wet, the bias stress at 20% elongation in the bias direction may be, for example, 7 N / 5 cm or more, preferably 10 N / 5 cm or more, more preferably 15 N / 5 cm or more, and particularly preferably 20 N / 5 cm or more. The upper limit is not particularly limited, but may be about 100 N / 5 cm. The bias stress at 20% elongation is a value measured by the method described in the Examples section below.

[0037] When the nonwoven fabric of one embodiment is saturated with water and / or 300% wet, the unit weight (g / m ２ The MD stress (N / 5 cm) at 20% elongation in the MD per unit length (N / 5 cm) may be, for example, 0.40 or more, preferably 0.60 or more, and more preferably 0.70 or more. The upper limit of this ratio may be, for example, 1.0 or less.

[0038] When the nonwoven fabric of one embodiment is saturated with water and / or 300% wet, the unit weight (g / m ２The CD stress (N / 5 cm) at 20% elongation in the CD per unit area (N / 5 cm) may be, for example, 0.10 or more, preferably 0.13 or more, and more preferably 0.15 or more. The upper limit of this ratio may be, for example, 0.50 or less.

[0039] Furthermore, from the viewpoint of further enhancing washing durability, the ratio of the stress (N / 5 cm) at 20% elongation in the bias direction of the nonwoven fabric of one embodiment when saturated with moisture and / or 300% wet to the average breaking strength (N / 5 cm) of the nonwoven fabric in MD and CD when 300% wet (bias stress / average breaking strength) may be, for example, 0.10 to 1.00, preferably 0.13 to 0.95, more preferably 0.15 to 0.90, and even more preferably 0.18 to 0.90.

[0040] One embodiment of the nonwoven fabric has excellent softness when wet. For example, when a nonwoven fabric having a long side of 30 cm and a short side of 5 cm (when 200% wet) is placed on a horizontal surface with the long sides of the nonwoven fabric in the MD or CD, and the nonwoven fabric is folded in half, the curved shape of the approximately central portion of the nonwoven fabric that is formed when the nonwoven fabric is folded in half, i.e., the curved shape of the nonwoven fabric formed by lifting one short side and folding it over the other short side, is observed from the side of the nonwoven fabric. The distance from the horizontal plane to the maximum height of the curved shape may be, for example, 30 mm or less, preferably 25 mm or less, and more preferably 22 mm or less in the MD, and / or 30 mm or less, preferably 25 mm or less, and more preferably 20 mm or less in the CD.

[0041] Specifically, a schematic perspective view of one embodiment of a nonwoven fabric will be described using Figure 3. The nonwoven fabric in Figure 3 has a long side in the MD and a short side in the CD. This nonwoven fabric has multiple linear attachment regions formed in the MD. The nonwoven fabric is brought to a 200% wet state and then spread out on a horizontal surface and left to rest. Next, one short side is lifted and placed over the other short side without moving the other short side, forming a natural curve centered approximately at the center of the long side. The maximum height of the curve formed by the nonwoven fabric from the horizontal surface can be measured to determine the softness of the nonwoven fabric when wet. Nonwoven fabrics exhibit a constant maximum height depending on their composition, but the accuracy of the maximum height as an indicator can be improved by measuring the maximum height five times on samples cut from the same nonwoven fabric.

[0042] [Characteristics of Nonwoven Fabric at Standard Moisture Content] The MD breaking strength of one embodiment of a nonwoven fabric at standard moisture content may be, for example, 38 N / 5 cm or more, preferably 40 N / 5 cm or more, more preferably 45 N / 5 cm or more, and particularly preferably 50 N / 5 cm or more. The upper limit is not particularly limited, but may be about 250 N / 5 cm. The MD breaking strength is a value measured by the method described in the Examples below.

[0043] The CD breaking strength of one embodiment of the nonwoven fabric at the standard moisture content may be, for example, 10 N / 5 cm or more, preferably 15 N / 5 cm or more, and more preferably 20 N / 5 cm or more. The upper limit is not particularly limited, but may be about 320 N / 5 cm. The CD breaking strength is a value measured by the method described in the Examples below.

[0044] The average breaking strength of the nonwoven fabric of one embodiment at the standard moisture content is the average value of the MD breaking strength and the CD breaking strength, and may be, for example, 25 N / 5 cm or more, preferably 30 N / 5 cm or more, more preferably 35 N / 5 cm or more, and particularly preferably 45 N / 5 cm or more. The upper limit is not particularly limited, but may be about 250 N / 5 cm.

[0045] In the case of a nonwoven fabric, the ratio of the MD breaking strength (N / 5cm) to the CD breaking strength (N / 5cm) at the standard moisture content of the nonwoven fabric, which is an index showing the orientation of the fibers of the nonwoven fabric, may be, for example, 0.6 or more and less than 3.0, preferably 0.6 to 2.9, and more preferably 0.6 to 1.5, from the viewpoint of suppressing deformation due to stress applied during washing.

[0046] The breaking strength in the bias direction of the nonwoven fabric of one embodiment at the standard moisture content may be, for example, 25 N / 5 cm or more, preferably 30 N / 5 cm or more, more preferably 35 N / 5 cm or more, and particularly preferably 45 N / 5 cm or more. The upper limit is not particularly limited, but may be about 300 N / 5 cm.

[0047] The stress at 20% elongation in the MD of one embodiment of the nonwoven fabric at the standard moisture content may be, for example, 40 N / 5 cm or more, preferably 50 N / 5 cm or more, and more preferably 60 N / 5 cm or more. The upper limit is not particularly limited, but may be about 200 N / 5 cm. The stress at 20% elongation in the MD is a value measured by the method described in the Examples below.

[0048] The stress at 20% elongation in the CD of one embodiment of the nonwoven fabric at the standard moisture content may be, for example, 10 N / 5 cm or more, preferably 13 N / 5 cm or more, and more preferably 15 N / 5 cm or more. The upper limit is not particularly limited, but may be about 100 N / 5 cm. The stress at 20% elongation in the CD is a value measured by the method described in the Examples below.

[0049] The stress at 20% elongation in the bias direction of one embodiment of the nonwoven fabric at the standard moisture content may be, for example, 15 N / 5 cm or more, preferably 20 N / 5 cm or more, and more preferably 25 N / 5 cm or more. The upper limit is not particularly limited, but may be about 150 N / 5 cm. The stress at 20% elongation in the bias direction is a value measured by the method described in the Examples below.

[0050] Furthermore, the ratio of the stress (N / 5 cm) at 20% elongation in the bias direction of one embodiment of the nonwoven fabric at the standard moisture content to the average breaking strength (N / 5 cm) in MD and CD at the standard moisture content of the nonwoven fabric (bias stress / average breaking strength) may be, for example, 0.30 or more, preferably 0.35 or more, and more preferably 0.37 or more. The upper limit is not particularly limited, but may be 2.00.

[0051] The MD deformation rate of the nonwoven fabric after 30 consecutive washings may be, for example, 90 to 110%, preferably 93 to 105%. The MD deformation rate of the nonwoven fabric is a value measured by the method described in the Examples below.

[0052] The CD deformation rate of the nonwoven fabric after 30 consecutive washings may be, for example, 90 to 110%, preferably 93 to 105%. The CD deformation rate of the nonwoven fabric is a value measured by the method described in the Examples below.

[0053] In one embodiment of the nonwoven fabric, the MD wicking length after absorbing water for 1 minute, which is an index of water absorbency, may be, for example, 40 mm or more, preferably 45 mm or more, and more preferably 50 mm or more. The upper limit of the MD wicking length is not particularly limited, but may be, for example, 80 mm. The MD wicking length is a value measured by the method described in the Examples below.

[0054] In one embodiment of the nonwoven fabric, the CD wicking length after absorbing water for 1 minute, which is an index of water absorbency, may be, for example, 40 mm or more, preferably 45 mm or more, and more preferably 50 mm or more. The upper limit of the CD wicking length is not particularly limited, but may be, for example, 80 mm. The CD wicking length is a value measured by the method described in the Examples below.

[0055] [Constituent Fibers of Nonwoven Fabric] The fibers constituting the nonwoven fabric are not particularly limited as long as the nonwoven fabric exhibits a predetermined water absorbency, but may contain hydrophilic fibers to improve water absorbency. The hydrophilic fibers are not particularly limited, but natural fibers, regenerated fibers, semi-synthetic fibers, and synthetic fibers can be used. Furthermore, the hydrophilic fibers may be fibers that have been imparted hydrophilic properties by post-processing. One type of hydrophilic fiber may be used alone, or two or more types may be used in combination. Examples of hydrophilic natural fibers include natural cellulose fibers such as cotton, hemp, wool, and pulp. Examples of hydrophilic regenerated fibers include regenerated cellulose fibers such as rayon, lyocell such as Tencel (registered trademark), polynosic, and cupra. Examples of hydrophilic semi-synthetic fibers include semi-synthetic cellulose fibers such as acetate and triacetate. Suitable examples of hydrophilic synthetic fibers include synthetic fibers composed of thermoplastic resins having hydrophilic functional groups such as hydroxyl groups, carboxyl groups, and sulfonic acid groups, and / or hydrophilic bonds such as amide bonds. Among these, preferred hydrophilic fibers may be cellulose fibers such as natural cellulose fibers, regenerated cellulose fibers, and semi-synthetic cellulose fibers. More preferred are rayon fibers (e.g., viscose rayon) and solvent-spun cellulose fibers (e.g., lyocell such as Tencel) among the regenerated cellulose fibers.

[0056] To ensure sufficient absorbency and water retention, the proportion of hydrophilic fibers (particularly hydrophilic fibers as the main fibers) in the fibers constituting the nonwoven fabric may be, for example, 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more. There is no particular upper limit to the proportion of hydrophilic fibers, but it may be, for example, 100% by mass or less.

[0057] The fibers constituting the nonwoven fabric may contain various synthetic fibers and natural fibers other than hydrophilic fibers. Examples of synthetic fibers other than hydrophilic fibers include polyolefin fibers such as polyethylene fibers and polypropylene fibers, polyester fibers such as polyethylene terephthalate fibers, polybutylene terephthalate fibers, and polylactic acid fibers, and composite fibers whose outer skin is made of a hydrophobic resin.

[0058] In addition to the main fibers, the nonwoven fabric may contain binder fibers capable of bonding the fibers in the nonwoven fabric together by thermal or chemical fusion. Preferred binder fibers include fibers whose outer skin contains a resin component with a lower melting point than the main fibers. The binder fibers may be non-composite or composite fibers. Composite fibers may, for example, be composite fibers having a core-sheath structure with a low-melting-point resin as the sheath component and a high-melting-point resin as the core component. The low-melting-point resin and the high-melting-point resin may be selected appropriately depending on the melting points of the fiber-forming resins described above for synthetic fibers. Preferred combinations include polyolefin resins such as polyethylene and polypropylene as low-melting-point resins and polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid as high-melting-point resins. Even when binder fibers are included, the binder fibers merely form point bonds between the fibers and are not included in the binder attachment sites in the nonwoven fabric.

[0059] From the viewpoint of improving the flexibility of the nonwoven fabric, the proportion of binder fibers among the fibers constituting the nonwoven fabric may be, for example, 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less.

[0060] The fiber length of the constituent fibers of the nonwoven fabric (e.g., main fibers, binder fibers) may be, for example, about 20 to 70 mm, preferably about 25 to 65 mm, more preferably about 30 to 60 mm, and even more preferably about 35 to 55 mm.

[0061] In order to ensure softness, the constituent fibers of the nonwoven fabric (for example, the main fibers and binder fibers) may have a fineness of, for example, about 1.0 to 3.5 dtex, preferably about 1.3 to 3 dtex, and more preferably about 1.5 to 2.5 dtex.

[0062] [Binder] The binder contains at least an adhesive component. Examples of the adhesive component include acrylic resins (such as acrylic acid ester copolymer resins), polyurethane resins, vinyl acetate copolymer resins, epoxy resins, and styrene resins (such as styrene-acrylic copolymer resins). Preferably, the binder contains at least one resin selected from the group consisting of acrylic resins, polyurethane resins, and styrene resins.

[0063] The binder may further contain at least one selected from the group consisting of a pigment, a penetrating agent, and a thickener, as necessary. Known or commonly used pigments, penetrating agents, and thickeners can be used depending on the purpose and composition. When the binder contains a pigment, a desired pattern can be imparted to the nonwoven fabric of the present invention by partially coating the binder. As described above, the smaller the ratio of the exposed area of ​​the binder on the front and back surfaces, the more uniform the pattern on the front and back surfaces of the nonwoven fabric, resulting in an excellent design.

[0064] In one embodiment of the nonwoven fabric, from the viewpoint of achieving both softness of the nonwoven fabric and the ability to bind the fibers in the nonwoven fabric, the binder adhesion rate may be, for example, 2 to 50 mass %, preferably 3 to 40 mass %, more preferably 4 to 30 mass %, and particularly preferably 5 to 20 mass %. Here, the binder adhesion rate is a value measured by the method described in the Examples below.

[0065] Such nonwoven fabrics have excellent washing durability and can be easily washed in a washing machine, and even after repeated washing, the nonwoven fabrics maintain excellent durability, making them useful as wipers for commercial use, industrial use, etc. Furthermore, they can be easily washed in a washing machine in ordinary households, and can be used as household cloths to reduce the time spent on daily housework.

[0066] (Method for producing nonwoven fabric) The method for producing a nonwoven fabric of the present invention includes at least the steps of: subjecting a web having at least a cross-web structure to an entanglement treatment using a high-pressure water stream at a water pressure of 5 MPa or more to obtain a nonwoven fabric raw roll; and applying a binder liquid to the nonwoven fabric raw roll by dip nip or coating.

[0067] [Nonwoven Fabric Raw Material] Nonwoven fabric raw material is prepared by the following method. First, a web is formed from predetermined fibers by carding or air-laid. To increase the bias stress of the nonwoven fabric at 20% elongation in the bias direction when saturated with moisture and / or 300% wet, the web has at least a cross-web structure, and such a structure can be formed by including a cross-web. A cross-web is a web formed so that the fibers are oriented approximately in the CD of the nonwoven fabric. Furthermore, the cross-web may be combined with a random carded, semi-random carded, or parallel carded web, as necessary.

[0068] The proportion of the cross web may be, for example, 30% by mass or more, preferably 45% by mass or more, and more preferably 60% by mass or more, based on the total mass of the web. The upper limit of the proportion of the cross web is not particularly limited, but may be, for example, 95% by mass from the viewpoint of processability.

[0069] For example, the ratio of the cross web to the semi-random web may be 30 / 70 to 95 / 5, preferably 45 / 55 to 90 / 10, more preferably 60 / 40 to 90 / 10, in terms of the mass ratio of cross web / semi-random web.

[0070] Next, the fibers of the obtained web are bonded to each other to give it practical strength, thereby obtaining a raw nonwoven fabric. As a bonding method, the fibers can be three-dimensionally entangled by a hydroentanglement method.

[0071] In the hydroentanglement method, a high-pressure water jet is sprayed from a nozzle with fine holes onto a porous support on which a web is placed. The water jet penetrates the web and bounces off a steel plate, using this energy to entangle and bond the fibers.

[0072] In the entanglement treatment, the cross web is subjected to entanglement treatment using a high-pressure water stream with a water pressure of 5 MPa or more, and such high-pressure water stream can further entangle the fibers. The high-pressure water stream may be applied multiple times while gradually increasing the pressure. For example, the difference in pressure between the first high-pressure water stream and the final high-pressure water stream may be 0 to 5 MPa, and preferably 0 to 4 MPa.

[0073] The temperature of the water jet during the entanglement treatment may be, for example, 15° C. or higher, preferably 25° C. or higher, more preferably 35° C. or higher, and particularly preferably 40° C. or higher. The upper limit of the water jet temperature can be appropriately set depending on the type of fibers constituting the web, but may be, for example, 80° C. or lower.

[0074] Multiple porous supports may be used. For example, the nonwoven fabric may be passed through a first porous support to entangle the three-dimensional fibers, and then passed through a second porous support to provide the desired mesh structure. In this case, the second porous support may have a pattern shape corresponding to the desired mesh structure. A preliminary entanglement treatment may be performed prior to the high-pressure water flow treatment. The preliminary entanglement treatment may be performed using a water flow with a water pressure of less than 5 MPa. The water flow for the preliminary entanglement treatment is preferably 0.5 to 4 MPa, and more preferably 0.8 to 3.5 MPa.

[0075] In order to adjust the binder distribution to a specific value, the nonwoven fabric raw material has a basis weight of, for example, 10 g / m ２ More than 100g / m ２ It may be less than 20 to 95 g / m ２ More preferably, 30 to 90 g / m ２ It may be to some extent.

[0076] (Binder Application Step) A raw nonwoven fabric (hereinafter sometimes simply referred to as raw fabric) is subjected to a step of applying a binder liquid by dip nip or coating. The binder liquid may be used as an emulsion in which the above-mentioned adhesive component and other optional components are dispersed in an aqueous solvent such as water, as necessary. When used as an emulsion, the viscosity of the binder can be appropriately determined by adjusting the solid content concentration, etc., depending on the method of applying the binder and the amount applied. For example, the solid content concentration can be selected from the range of 0.2% by mass to 60% by mass, and the viscosity can be selected from the range of 1 to 500 mPa·s.

[0077] In the case of coating, the binder liquid may be applied to the entire surface of the raw sheet or to a portion thereof. Examples of the coating method include printing, spraying, and foaming. However, the printing method is preferred from the viewpoint of being able to control the area to which the binder is applied.

[0078] In the printing method, the raw web is brought into contact with a roll to which a binder has been applied, and the binder is applied to the surface of the raw web that is in contact with the roll. When printing, the binder may be applied according to the pattern to be formed on the surface of the final product. Such a pattern is not particularly limited, and may be any of various linear shapes as defined by the above-mentioned L1 / L2.

[0079] The moisture content of the raw sheet before coating may be adjusted to 50 to 450% by mass. By adjusting the raw sheet to a specific moisture content before coating, the binder coated on the surface can be dispersed in the water held by the raw sheet and can sufficiently penetrate into the interior of the raw sheet. The moisture content of the raw sheet before coating may be preferably 80 to 350%, more preferably 100 to 200%.

[0080] In the case of the dip nip method, the raw material is immersed in a binder liquid, and then the raw material is squeezed with, for example, a mangle to remove excess binder liquid, allowing the binder to penetrate into the entire surface and interior of the raw material.

[0081] When dip-nipping is performed, the nonwoven fabric raw sheet may be dried before being immersed in the binder and used in a state of 0% moisture content. Furthermore, the binder content of the nonwoven fabric raw sheet after dip-nipping may be adjusted to 50 to 800% by mass, more preferably 80 to 500%, and even more preferably 100 to 250%. The binder content of the raw sheet may be adjusted, for example, by the transport speed or nip pressure when the raw sheet is immersed.

[0082] (Drying Process) Preferably, in the drying process, the front and back surfaces of the raw web to which the binder liquid has been applied are alternately contacted with different heated rolls using a cylinder dryer for drying. This allows the binder to migrate to the surface of the raw web that is in contact with the heated roll as moisture migrates within the raw web. Specifically, as moisture evaporates on the surface of the raw web that is in contact with the heated roll, the moisture diffuses to areas of the raw web that are lacking moisture due to evaporation, and as this diffusion occurs, solids such as adhesive components dispersed in water migrate to the surface in contact with the heated roll. Next, when the raw web contacts the next heated roll, the surface of the raw web that is in contact with the next heated roll is heated relatively more, so the direction of moisture diffusion is reversed. As moisture migrates toward the heated roll, solids such as adhesive components migrate to the surface in contact with the heated roll. Therefore, even if the binder is applied to only one surface, it can be attached to the opposite surface. Then, by drying the front and back surfaces by alternately contacting them with different heated rolls, solid components such as adhesive components can be passed through the interior and transferred to the front and back surfaces, and after drying, the binder can be distributed so that it is more abundant on the surface of the nonwoven fabric than inside the nonwoven fabric.

[0083] Furthermore, for example, as shown in FIG. 4 , when the binder is coated on only one surface of the raw nonwoven fabric 10, the uncoated surface 12, which is the surface opposite the coated surface 11, is first contacted with the first heated roll 30 during the drying process, and then the coated surface 11 is contacted with the second heated roll 31. The uncoated surface 12 is then contacted with the third heated roll 32, and then the coated surface 11 is contacted with the fourth heated roll 33. If necessary, the uncoated surface 12 and the coated surface 11 may be dried alternately by contacting them with different heated rolls. By first contacting the uncoated surface with the heated roll during the drying process, the solids in the binder, which are more concentrated on the coated surface, can be transferred to the uncoated surface while the raw fabric still contains a large amount of moisture, which acts as a medium for the transfer of solids in the binder. This improves the uniformity of the binder distribution on both surfaces of the resulting nonwoven fabric.

[0084] In the drying step, the temperature of the heated roll may be 100°C or higher (e.g., about 100 to 150°C), preferably 110°C or higher (e.g., about 110 to 145°C (e.g., about 110 to 140°C)), and more preferably 120°C or higher (e.g., about 120 to 140°C). The front and back surfaces of the raw sheet may each be dried two or more times, preferably three or more times. There is no particular upper limit to the number of times the front and back surfaces of the raw sheet are dried, but from the viewpoint of productivity, it may be, for example, eight or fewer times (preferably seven or fewer times).

[0085] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, various physical properties were measured by the following methods.

[0086] [Basis weight (g / m ２ ) ] In accordance with 6.2 of JIS L 1913 "General nonwoven fabric testing method", the basis weight (g / m ２ ) was measured.

[0087] [Thickness] According to JIS L 1913 "General nonwoven fabric testing method" 6.1, pressing pressure: 12 g / cm ２ The thickness of the nonwoven fabric was measured using a measuring instrument with a pressure plate diameter of 1.0 inch.

[0088] [Binder adhesion rate] Filter paper (made of polypropylene) was dried completely, and the bone-dry weight was measured as A (g). Next, a nonwoven fabric sample was cut into 15 cm square pieces, placed in a glass beaker, and immersed in concentrated sulfuric acid to dissolve the fibers in the nonwoven fabric in a 96% sulfuric acid solution (concentrated sulfuric acid), and the resulting mixture was filtered through the PP filter paper. Furthermore, the residue remaining in the glass beaker was completely washed into the filter paper with a 75% sulfuric acid solution. Thereafter, the filter paper was washed with running water so that no sulfuric acid remained, and the filter paper was bone-dried with the filtrate still included, and the total bone-dry weight was measured as B (g). The residue that was not dissolved in sulfuric acid and remained after filtration was considered to be the amount of binder attached to the fiber, and the binder adhesion amount C (g / m) was calculated using the following formula: ２ C (g / m ２ )=(B-A) / 15 / 15×10000 The ratio of the obtained binder adhesion amount C to the total basis weight of the nonwoven fabric, expressed as a percentage, was defined as the binder adhesion rate. Note that, if the binder adhesion amount can be calculated from the manufacturing conditions, it may be a value calculated from the manufacturing conditions.

[0089] [Stress at 20% Elongation and Breaking Strength] The nonwoven fabric was cut into a width of 5 cm and a length of 15 cm, and pulled using a Shimadzu Autograph AGX-V with a chuck distance of 10 cm and a pulling speed of 20 cm / min. The stress at 20% elongation was read from the obtained measurement chart and used as the stress at 20% elongation. The strength at break was also measured and used as the breaking strength. This measurement was performed in the MD, CD, and bias directions using nonwoven fabrics at 300% wetness and at the standard moisture content. For nonwoven fabrics at saturated moisture content, the stress at 20% elongation and breaking strength in the bias direction were measured.

[0090] [Softness of Wet Nonwoven Fabric] A nonwoven fabric (200% wet) measuring 30 cm long and 5 cm short was placed on a horizontal surface with the MD or CD of the nonwoven fabric being the long side, and the curved shape of the approximately central part of the nonwoven fabric that was formed when the nonwoven fabric was folded in half, i.e., the curved shape of the nonwoven fabric formed by lifting one short side and folding it over the other short side, was observed from the side of the nonwoven fabric, and the distance from the horizontal plane to the maximum height of the curved shape was measured. The maximum height was determined as the average of five measurements taken on samples cut from the same nonwoven fabric.

[0091] [Washing durability (shape change)] According to JIS L 0217 103, the nonwoven fabric was washed 30 times and then evaluated for shape change, the presence or absence of tears, and the number of pills according to the following criteria.

[0092] (Dimensional Change Rate) As shown in Figure 5, a rectangular nonwoven fabric sample with the long sides in the MD and the short sides in the CD was unfolded, and a ruler was placed along the measurement direction of the sample 10 cm away from the end of the nonwoven fabric sample to be measured. Then, as shown in Figure 6, the ruler was lightly pressed against the nonwoven fabric sample and slid, and the length of the flattened sample's side in the measurement direction was measured. Based on the measured nonwoven fabric length, a measuring plate as shown in Figure 7 was prepared. A rectangle with two long sides A0 and B0 and two short sides C0 and D0 of the nonwoven fabric sample was drawn on the measuring plate, and the center lines of each side were also drawn. Center lines of the sides of the nonwoven fabric sample were also drawn with an oil-based marker.

[0093] After washing the nonwoven fabric sample 30 times, the washed nonwoven fabric sample was placed on the measuring plate so that the center line of the nonwoven fabric sample coincided with the center line of the measuring plate, and the dimensional change rate of the nonwoven fabric sample was calculated based on the measuring plate. Specifically, as shown in Figure 8, if the long sides A0 and B0 of the measuring plate shrink by A1 and A2, and B1 and B2 at both ends, respectively, the dimensional change rates of the long sides A0 and B0 of the nonwoven fabric sample after washing can be calculated by subtracting the shrinkage amounts as (A0 - A1 - A2) / A0 x 100 and (B0 - B1 - B2) / B0 x 100, respectively, and the average of these values ​​can be used as the dimensional change rate of the long sides of the nonwoven fabric sample.

[0094] Furthermore, as shown in FIG. 9 , when the short sides C0 and D0 of the measuring plate are elongated by C1 and C2, and D1 and D2 at both ends, respectively, the dimensional change rates of the short sides C0 and D0 of the nonwoven fabric sample after washing can be calculated by adding up the elongations, as follows: (C0 + C1 + C2) / C0 × 100 and (D0 + D1 + D2) / D0 × 100, and the average value of these can be used as the dimensional change rate of the short sides.

[0095] (Tears) After washing, the number of tears of 10 mm or more on the two short sides of the nonwoven fabric sample was counted, and the average of these was evaluated as the number of tears of the nonwoven fabric sample. The average value of five repetitions was used as the number of tears.

[0096] (Pilling) A 20 cm square was drawn in the center of each nonwoven fabric sample before washing with an oil-based marker. After 30 washes, the number of pills (pilling) that had occurred within this square was counted on both the front and back surfaces of the nonwoven fabric sample, and the average value was used to evaluate the number of pills for the nonwoven fabric sample. The average value obtained through 5 repetitions was used as the value for the number of pills.

[0097] [Wicking Length (mm)] In accordance with the Byreck method of JIS L 1907 7.1.2, three test pieces were taken in each of the longitudinal and transverse directions, and adjusted so that the bottom ends were immersed in water (2% aqueous ink solution). The height of the water that rose after one minute was read, and the average value of the three pieces was taken as the wicking length.

[0098] [Water retention capacity, water retention rate (g, %)] Measurements were made in accordance with the water absorption rate specified in JIS L 1907 7.2. A test piece was cut into a 5 cm square and its weight A (g) was measured. The test piece was immersed in water for 30 seconds. After immersion, the test piece was pinched by one side and removed from the liquid, and its weight B (g) after 1 minute was measured as the water retention capacity. The water retention rate C (%) was calculated using the following formula: C (%) = [(B - A) / A] x 100.

[0099] Example 1 A fiber web was produced by using 70% by mass of rayon fiber (Corona manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm and 30% by mass of polyester fiber (Tetoron (registered trademark) 471 manufactured by Toray Industries, Inc.) having a fineness of 1.6 dtex and a fiber length of 51 mm, and spinning the resulting web with a parallel card. The web was then cross-wrapped with a cross wrapper, and a semi-random carded web having the same fiber composition was laminated on the resulting web so that the ratio of the basis weight of the cross web to the semi-random web was 65:35. The fibrous web was placed on a metal punching drum (first drum) with a diameter of 0.04 mm and an opening ratio of 9.5%. While suction was applied, a water stream of 1 MPa was applied to the fibrous web from an orifice with a diameter of 0.08 mm and a pitch of 0.6 mm, and then a water stream of 3 MPa was applied from an orifice with a diameter of 0.1 mm and a pitch of 0.6 mm. The fibrous web was then turned over and placed on a second drum. A high-pressure water stream of 5 MPa was applied to the fibrous web from an orifice with a diameter of 0.1 mm and a pitch of 0.6 mm, and then a high-pressure water stream of 6 MPa was applied from an orifice with a diameter of 0.1 mm and a pitch of 0.6 mm. The fibrous web was then turned over and placed on a #10 plain-woven polyester net conveyor. While suction was applied, a high-pressure water stream of 6 MPa was applied to the fibrous web three times from an orifice with a diameter of 0.1 mm and a pitch of 0.6 mm. The moisture content of the nonwoven fabric raw fabric, in which the fibers were entangled by the hydroentanglement treatment, was adjusted to 120% by mass, and a binder (acrylic emulsion) adjusted to a solids concentration of 40% and a viscosity of 100 to 150 mPa·s was applied to form a corrugated pattern with a pitch of 5.7 mm between adjacent corrugations. Then, using a cylinder dryer, the surface temperature of the drying treatment roll was set to 160°C, and the nonwoven fabric was repeatedly treated on both sides, alternating 10 times. Next, the surface temperature of the heat treatment roll was set to 140°C, and the nonwoven fabric was repeatedly treated on both sides, alternating 20 times. This series of processes was performed at a speed of 30 m / min (final drying treatment step), to produce a mesh-structured nonwoven fabric.

[0100] [Example 2] A mesh-structured nonwoven fabric was produced in the same manner as in Example 1, except that 100% by mass of rayon fiber ("Corona" manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm was used, hydroentangled under the conditions shown in Table 1, and the pitch between the corrugations formed by the binder was set to 5.2 mm.

[0101] Example 3 A mesh-structured nonwoven fabric was produced in the same manner as in Example 1, except that 80% by mass of rayon fiber (Corona manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm and 20% by mass of polyester fiber (Tetoron (registered trademark) 471 manufactured by Toray Industries, Inc.) having a fineness of 1.6 dtex and a fiber length of 51 mm were used, and hydroentangled under the conditions shown in Table 1, the web was stretched in the MD using a drafter to adjust the basis weight, and the series of processes was carried out at a speed of 15 m / min (final drying treatment step).

[0102] [Example 4] 100% by mass of rayon fiber ("Corona" manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm was used, and hydroentangled under the conditions shown in Table 1. After hydroentanglement, a binder (acrylic emulsion) was added at about 3.0 g / m by dip nip treatment. ２ A mesh-structured nonwoven fabric was produced in the same manner as in Example 2, except that a binder (acrylic emulsion) having a solid content of 40% and a viscosity of 100 to 150 mPa s was applied, the surface temperature of a heat treatment roll was set to 140°C, and the front and back of the nonwoven fabric were repeatedly treated 20 times to form a wavy pattern with a pitch of 12.4 mm.

[0103] Example 5 A mesh-structured nonwoven fabric was produced in the same manner as in Example 1, except that 50% by mass of rayon fiber ("Corona" manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm and 50% by mass of core: polyester / sheath: polyethylene composite fiber ("TJ04CEK" manufactured by Teijin Co., Ltd.) having a fineness of 2.2 dtex and a fiber length of 51 mm were used, and hydroentanglement was performed under the conditions shown in Table 1.

[0104] Example 6 A nonwoven fabric having a mesh structure was produced in the same manner as in Example 2, except that hydroentanglement was carried out under the conditions shown in Table 1.

[0105] Comparative Example 1 A fiber web was prepared by parallel carding using 90% by mass of rayon fiber ("Corona" manufactured by Daiwabo Rayon Co., Ltd.) with a fineness of 1.7 dtex and a fiber length of 40 mm and 10% by mass of a polyester core / modified polyester bicomponent fiber ("TJ04C2" manufactured by Teijin Co., Ltd.) with a fineness of 2.2 dtex and a fiber length of 51 mm. A water stream was applied on a metal punching drum (first drum) at pressures of 1 MPa and 4 MPa. The web was then turned over and subjected to high-pressure water streams on the second drum at pressures of 5 MPa and 6 MPa. The web was then turned over and placed on a #6 plain weave polyester net conveyor. While being suctioned, the web was subjected to high-pressure water streams at a pressure of 6 MPa three times from orifices with a diameter of 0.1 mm and a pitch of 0.6 mm. The water temperature used for hydroentangling was 20°C. Thereafter, using a cylinder dryer, the surface temperature of the drying treatment roll was set to 160°C, and the front and back of the nonwoven fabric were repeatedly treated 10 times, and a binder (acrylic emulsion) was applied by dip nip treatment. Next, the surface temperature of the heat treatment roll was set to 140°C, and the front and back of the nonwoven fabric were repeatedly treated 20 times. This series of processes was carried out at a speed of 25 m / min (final drying treatment step), and a mesh-structured nonwoven fabric was produced.

[0106] [Comparative Example 2] A web was entangled under the conditions shown in Table 1, and the binder coating amount was 0 g / m ２ A mesh-structured nonwoven fabric was produced in the same manner as in Example 1, except that the solid content was 100g.

[0107] Comparative Example 3 A nonwoven fabric having a mesh structure was produced in the same manner as in Example 2, except that hydroentanglement was carried out under the conditions shown in Table 1.

[0108] Comparative Example 4: Using 100% by mass of rayon fiber ("Corona" manufactured by Daiwabo Rayon Co., Ltd.) having a fineness of 1.7 dtex and a fiber length of 40 mm, a fabric was produced using a semi-random card to obtain a fabric with a basis weight of approximately 50.0 g / m ２A mesh-structured nonwoven fabric was produced in the same manner as in Example 4, except that the semi-random fiber web of Example 1 was hydroentangled under the conditions shown in Table 1, and the amount of binder (acrylic emulsion) applied was adjusted to a solids concentration of 40% and a viscosity of 100 to 150 mPa s.

[0109] The structure and properties of the obtained nonwoven fabric are shown in Tables 1 and 2.

[0110]

[0111] As shown in Tables 1 and 2, in Comparative Example 1, the bias stress (N / 5 cm) at 20% elongation in the bias direction of the nonwoven fabric when saturated with moisture and when 300% wet, and the basis weight (g / m) of the nonwoven fabric at the standard moisture content were ２ The ratio (bias stress / basis weight) of the tensile strength to the total strength (bias stress / basis weight) was 0.09 in both cases, and the dimensional change rate after 30 washes was large, and many tears occurred after 30 washes.

[0112] In Comparative Example 2, since there were no binder attachment sites, not only was the nonwoven fabric deformed to the point where it lost its original shape after 30 washes, but a large amount of pilling occurred. In addition, since there were no binder attachment sites in Comparative Example 2, the breaking strength at saturated moisture tended to decrease.

[0113] In Comparative Example 3, the same material as in Example 2 was used, but the bias stress (N / 5 cm) at 20% elongation in the bias direction when the nonwoven fabric was saturated with moisture and 300% wet, and the basis weight (g / m) of the nonwoven fabric at the standard moisture content were ２ The ratio of the bias stress to the fabric weight (bias stress / basis weight) was 0.09 and 0.08, respectively, so the dimensional change rate after 30 washes was large and many tears occurred after 30 washes. Furthermore, the breaking strength and 20% stress were lower than those of Example 2 in all of the MD, CD, and bias directions.

[0114] In Comparative Example 4, the nonwoven fabric was obtained by changing the conditions of Example 4. The bias stress (N / 5cm) at 20% elongation in the bias direction when the nonwoven fabric was saturated with moisture and 300% wet, and the basis weight (g / m) of the nonwoven fabric at the standard moisture content were measured. ２The ratios (bias stress / basis weight) of the dimensional change rate after 30 washes were 0.09 and 0.10, respectively, and the dimensional change rate after 30 washes was larger than that of Example 4. Many tears still occurred after 30 washes. Furthermore, the breaking strength and 20% stress in the CD and bias directions were significantly lower than those of Example 4.

[0115] On the other hand, in Examples 1 to 6, not only did they have high water absorbency, but also the ratio (bias stress / basis weight) was 0.15 or more and they had binder attachment sites, so all of them were able to reduce the dimensional change rate after 30 washes. Furthermore, no tearing occurred even after 30 washes, and the nonwoven fabric of Example 1 remained in the state shown in Figure 10 even after 30 washes, and similar states were observed in the other Examples.

[0116] As described above, the nonwoven fabric of the present invention has excellent washing durability and is therefore useful as a cleaning nonwoven fabric that can be washed and reused, and can be suitably used as various industrial wipers or household wipers, for example, wipers used to wipe various electrical appliances, furniture (e.g., tables, chests of drawers, etc.), kitchen utensils (e.g., cutting boards, countertops, sinks, gas stoves, tableware, etc.), as well as window glass, ceilings, floors, walls, etc.

[0117] As described above, a preferred embodiment of the present invention has been described with reference to the drawings, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention, and such additions, modifications, or deletions are also included within the scope of the present invention. A brief explanation of the symbols

[0118] 10: Raw nonwoven fabric 11: Coated surface 12: Uncoated surface 30: First heated roll 31: Second heated roll 32: Third heated roll 33: Fourth heated roll L1: Distance between the top and bottom of the line L2: Line width X: Distance between the peaks

Claims

1. A nonwoven fabric having a binder attachment portion, the bias stress (N / 5cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet, and the basis weight (g / m2) of the nonwoven fabric at the standard moisture content ２ ) is 0.15 or more.

2. In the nonwoven fabric according to claim 1, the bias stress (N / 5cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet, and the basis weight (g / m2) of the nonwoven fabric at the standard moisture content ２ ) is 0.35 or more.

3. The nonwoven fabric according to claim 1 or 2, in which the ratio of the breaking strength (N / 5cm) in the machine direction (hereinafter referred to as MD) to the breaking strength (N / 5cm) in the direction perpendicular to the MD (hereinafter referred to as CD) at the standard moisture content of the nonwoven fabric (MD breaking strength / CD breaking strength) is 0.6 or more and less than 3.

0.

4. The nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric has a bias breaking strength of 25 N / 5 cm or more at the standard moisture content.

5. The nonwoven fabric according to claim 1 or 2, wherein the adhesion rate of the binder is 2 to 50 mass %.

6. The nonwoven fabric according to claim 1 or 2, having a fiber arrangement structure derived from a cross web.

7. The nonwoven fabric according to claim 1 or 2, having a basis weight of 30 to 250 g / m ２ That is, nonwoven fabric.

8. The nonwoven fabric according to claim 1 or 2, wherein the ratio (bias stress / average breaking strength) of the stress (N / 5cm) at 20% elongation in the bias direction when the nonwoven fabric is saturated with moisture and / or 300% wet to the average breaking strength (N / 5cm) in MD and CD when the nonwoven fabric is 300% wet is 0.10 to 1.

00.

9. The nonwoven fabric according to claim 1 or 2, wherein when the nonwoven fabric (long side 30 cm x short side 5 cm) is placed at a 200% wet state on a horizontal surface with either the MD or CD of the nonwoven fabric as the long side, and one short side is lifted and laid over the other short side to form a curved shape of the nonwoven fabric, when observed from the side of the nonwoven fabric, the distance from the horizontal surface to the maximum height of the curved shape is 30 mm or less in the MD and / or 30 mm or less in the CD.

10. The nonwoven fabric according to claim 1 or 2, comprising hydrophilic fibers in an amount of 50% by mass or more.

11. The nonwoven fabric according to claim 1 or 2, wherein the binder is present continuously on both sides of the nonwoven fabric.

12. The nonwoven fabric of claim 1 or 2, wherein the nonwoven fabric has a plurality of apertures, the colored binder forms a continuous row of wavy patterns in the CD of the nonwoven fabric, and the wavy patterns are present in a plurality of rows of the wavy patterns that are approximately equally spaced from one another in the MD of the nonwoven fabric.

13. The nonwoven fabric according to claim 1 or 2, having a water retention rate of 400% or more.

14. A wiper comprising the nonwoven fabric according to claim 1 or 2.

15. A method for producing a nonwoven fabric, comprising: a step of subjecting a web having at least a cross-web structure to an entanglement treatment using a high-pressure water flow having a water pressure of 5 MPa or more to obtain a nonwoven fabric raw material; and a step of applying a binder liquid to the nonwoven fabric raw material by dip nip or coating.

16. A method for producing nonwoven fabric as claimed in claim 15, further comprising a step of drying the raw nonwoven fabric to which the binder liquid has been applied by alternately contacting the raw nonwoven fabric with a plurality of heated rolls using a cylinder dryer.

17. The method for producing a nonwoven fabric according to claim 15 or 16, wherein the temperature of the water flow in the entanglement treatment is 35° C. or higher.

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