Nonwoven fabric for objective wiper and objective wiper

Abstract

To provide a nonwoven fabric for liquid impregnation, a nonwoven fabric for a wiper that is high in dirt collection ability.SOLUTION: A nonwoven fabric for an objective wiper is a fabric layer (a) which includes a first fabric layer, a second fabric layer, and an intermediate fabric layer situated between the first fabric layer and the second fabric layer, one of the first fabric layer and second fabric layer is a fiber layer a which has 50 mass percent or more of a hydrophilic cellulose fiber, and the intermediate fabric layer is a wet type nonwoven fabric including 50 mass percent or more of the hydrophilic cellulose fiber, and / or of a short fiber having a fiber length of 20 mm or less. Each fabric layer is integrated by cross connection of the fibers, where a MD 5% elongation stress index for which 5% elongation stress (N / 5 cm) in a MD direction under a dry condition is divided by basis weight (g / m2) of the nonwoven fabric is 0.150 or higher, and / or 5% elongation stress (N / 5 cm) in the MD direction under a humid condition divided by the basis weight (g / m2), namely MD 5% elongation stress index is 0.050 or higher.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a nonwoven fabric for an object wiper and a wiper including the nonwoven fabric. [Background technology]

[0002] One of the uses of nonwoven fabrics is a wiper (object wiper) for wiping off dirt from an object. For example, Patent Document 1 describes a nonwoven fabric wiper including fibers having a curved portion, at least a part of the curved portion having multiple bends, and the curved portion having multiple bends is formed within 1 mm of the surface of the nonwoven fabric wiper. 2 It has been proposed that wipers having two or more per wiper be used as industrial wipers suitable for wiping uneven surfaces (for example, fine mesh used in screen printing).Patent Document 2 also proposes that a fiber sheet formed of biodegradable fibers containing at least water-absorbent fibers is impregnated with a cleaning composition consisting of a compound recognized as a food and / or food additive, and that the fiber sheet be used for wiping in a wet state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-068032 A [Patent Document 2] JP 2000-102492 A Summary of the Invention [Problem to be solved by the invention]

[0004] To provide a nonwoven fabric which provides an object wiper with high dirt collecting properties. [Means for solving the problem]

[0005] The nonwoven fabric according to the present disclosure has a first fiber layer, a second fiber layer, and an intermediate fiber layer located between the first fiber layer and the second fiber layer, one of the first fiber layer and the second fiber layer is a fiber layer a containing 50% by mass or more of hydrophilic cellulose fibers, The intermediate fiber layer is a fiber layer containing 50% by mass or more of hydrophilic cellulose fibers, and / or a wet-laid nonwoven fabric, The stress (N / 5cm) at 5% elongation in the MD direction in a dry state is expressed as the basis weight (g / m 2 ) is 0.150 or more, and / or the stress (N / 5cm) at 5% elongation in the MD direction in a wet state in which 100 parts by mass of nonwoven fabric are soaked in 250 parts by mass of water is divided by the weight (g / m 2 ) The stress index at MD5% elongation divided by is 0.050 or more. This is a nonwoven fabric for objective wipers. Effect of the Invention

[0006] When the nonwoven fabric of the present disclosure is used as an object wiper, dirt once taken in by the nonwoven fabric is less likely to fall off, improving the wiper's ability to collect dirt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] (How the nonwoven fabric for wipers of the present disclosure came about) Object wipers are used to remove various types of dirt from various objects. For example, wipers for cleaning floors are designed to remove not only fine dirt such as dust, but also solid particles larger than dust, such as food crumbs and hair, and so emphasis is placed on the ability to capture slightly larger solid particles (the ability to retain wiped dirt within the wiper).

[0008] The inventors of the present invention have considered a configuration for improving the collection of various types of dirt, including solid dirt of a somewhat large size, and have concluded that when a wiper is used to wipe an object (e.g., a floor of several tatami mats) by rubbing it, the wiper is likely to be loaded due to static friction in the early stages of the wiping action, which causes twisting and stretching, and the initial collection ability is not fully demonstrated. On the other hand, they also considered that when a certain amount of dirt is collected from the middle to late stages of the wiping action, the voids in the wiper are reduced and the wiper is saturated with dirt, and it is not possible to collect a large amount of dirt. Furthermore, they also considered that the twisting and stretching of the wiper that occurs during the wiping operation causes deformation or expansion of the voids between the fibers, which causes the held dirt to fall off.

[0009] Therefore, the inventors of the present invention have studied the relationship between the twisting and elongation that occurs during wiping work, the dirt collection ability, and the shedding of dirt during wiping work, and have considered that the twisting and elongation are related to the stress at 5% elongation in the MD direction (also called the machine direction) of the nonwoven fabric constituting the wiper. They have found that a nonwoven fabric configured so that the stress index at 5% elongation in the MD direction, obtained by dividing the stress at 5% elongation in the MD direction by the basis weight, is equal to or greater than a predetermined value, can improve the dirt collection ability. In addition, when such a nonwoven fabric is manufactured by an entanglement treatment method using a high-pressure fluid flow, the fluid marks formed as streaky unevenness by the injection of the fluid flow tend to become clearer, and it was inferred that the unevenness plays a role of scraping off dirt and also holds the dirt, thereby further improving the dirt collection ability.

[0010] The total energy of the water jet sprayed onto the fiber web is adjusted to form streaky irregularities that are continuous in the MD direction, with the concaves tending to be approximately 0.5 mm wide and the convexities approximately 1.0 mm wide. As a representative example of dirt, hair is generally said to be approximately 0.1 mm thick at most, and is large enough to fit into the concaves of the above size, so when this uneven shape is clearly present, it is expected that more dirt (especially hair) will be captured. Hereinafter, an embodiment of the nonwoven fabric for an object wiper according to the present disclosure will be described.

[0011] (Composition of nonwoven fabric) The nonwoven fabric according to the embodiment of the present disclosure includes a first fiber layer, a second fiber layer, and an intermediate fiber layer located between the first fiber layer and the second fiber layer, one of the first fiber layer and the second fiber layer is a fiber layer a containing 50% by mass or more of hydrophilic cellulose fibers, the intermediate fiber layer is a fiber layer containing 50% by mass or more of hydrophilic cellulose fibers and / or a wetlaid nonwoven fabric made of short fibers having a fiber length of 20 mm or less; Each fiber layer is integrated by intertwining the fibers. The stress (N / 5cm) at 5% elongation in the MD direction in a dry state is expressed as the basis weight (g / m 2 ) is 0.150 or more, and / or the stress (N / 5cm) at 5% elongation in the MD direction in a wet state in which 100 parts by mass of nonwoven fabric are soaked in 250 parts by mass of water is divided by the weight (g / m 2 The nonwoven fabric for objective wipers has a stress index at MD 5% elongation, calculated by dividing the stress index by the fiber length by the fiber length, of 0.050 or more.

[0012] In the nonwoven fabric for object wipers of this embodiment (hereinafter, simply referred to as "nonwoven fabric"), one of the first fiber layer and the second fiber layer is a fiber layer a containing 50% by mass or more of hydrophilic cellulose fibers, and the intermediate fiber layer is a fiber layer containing 50% by mass or more of hydrophilic cellulose fibers, and / or a wet nonwoven fabric. As described below, when a nonwoven fabric is manufactured by a method of entangling fibers using a high-pressure water flow as a high-pressure fluid flow, the hydrophilic cellulose fibers promote entanglement of the fibers, facilitating the manufacture of a nonwoven fabric having a high MD5% elongation stress. Therefore, in a configuration in which both the fiber layer a and the intermediate fiber layer contain hydrophilic cellulose fibers, the hydrophilic cellulose fibers make it easy to obtain a nonwoven fabric having a high MD5% elongation stress. In addition, when a nonwoven fabric is manufactured by a method of entangling fibers using a high-pressure fluid flow, even when the intermediate fiber layer is a wet nonwoven fabric made of short fibers, entanglement of the fibers tends to progress more. Therefore, even in a configuration in which the fibrous layer a contains hydrophilic cellulose fibers and the intermediate fibrous layer is a wet-laid nonwoven fabric, it is easy to obtain a nonwoven fabric with high stress at MD 5% elongation.

[0013] The hydrophilic cellulose fibers themselves have water absorption properties and can store liquid. Therefore, when the nonwoven fabric of this embodiment is impregnated with liquid, the hydrophilic cellulose fibers contained in the fiber layer and the intermediate fiber layer, together with the interfiber voids formed in the nonwoven fabric, serve to retain the liquid impregnated in the nonwoven fabric. Alternatively, when the nonwoven fabric of this embodiment is used as a dry-type wiper for an object, when wiping off liquid, the hydrophilic cellulose fibers contained in the fiber layer a and the intermediate fiber layer absorb the wiped liquid and make it difficult for the liquid to remain on the object.

[0014] The hydrophilic cellulose fibers contained in the fiber layer a which is the first fiber layer and / or the second fiber layer of the nonwoven fabric of this embodiment will be described in detail below, and the fiber layer a contains 50% by mass or more of the hydrophilic cellulose fibers, particularly 55% by mass or more, more particularly 60% by mass or more, and even more particularly 75% by mass or more. The fiber layer a may be composed of only hydrophilic cellulose fibers. If the ratio of hydrophilic cellulose fibers is small, the amount of liquid impregnated into the nonwoven fabric becomes small, and depending on the application, the wettability may be insufficient or the wiping ability of the liquid may be reduced. In addition, if the ratio of hydrophilic cellulose fibers is small, when the nonwoven fabric is manufactured using a high-pressure water flow as described below, the fibers may not be sufficiently entangled with each other, and the stress index at MD5% elongation in the above range may not be obtained.

[0015] In addition to hydrophilic cellulose fibers, the fiber layer a may contain other fibers, particularly synthetic fibers as the other fibers. Synthetic fibers are preferably used because they improve the mechanical strength of the nonwoven fabric and impart rigidity to the nonwoven fabric. The details of the synthetic fibers will be described later. When the fiber layer a contains synthetic fibers as other fibers, the proportion of the synthetic fibers in the fiber layer a may be more than 0% by mass and not more than 50% by mass, particularly 5% by mass to 45% by mass, more particularly 10% by mass to 40% by mass, and even more particularly 15% by mass to 25% by mass. If the proportion of synthetic fibers exceeds 50% by mass, the proportion of hydrophilic cellulose fibers decreases accordingly, and the amount of liquid impregnated may decrease when the liquid is impregnated. In addition, if the proportion of synthetic fibers is too large, the fibers may not be sufficiently entangled when entangled with each other by high-pressure water flow, and the stress index at MD5% elongation in the above range may not be obtained. Furthermore, if the proportion of synthetic fibers is too high, the inter-fiber voids in the nonwoven fabric may become excessively large. Since the liquid held in the large inter-fiber voids is easily released once by wiping pressure, if the proportion of synthetic fibers is too high, the sustained release of liquid from the nonwoven fabric when it is pre-impregnated with liquid may decrease, or the wiped liquid may be released again onto the target object.

[0016] When the fiber layer a contains two or more types of synthetic fibers, at least one type of synthetic fiber may be used as an adhesive fiber, and at least one type of synthetic fiber may be present as a non-adhesive fiber. Here, the non-adhesive fiber is one that does not melt or soften and retains its fiber shape at a temperature at which the adhesive component of the adhesive fiber melts or softens to bond the fibers together. Therefore, whether it is an adhesive fiber or a non-adhesive fiber is determined by the resin that constitutes each fiber and the conditions (heating temperature) when manufacturing the nonwoven fabric. For example, a synthetic fiber containing polyethylene as one component may be subjected to a heat treatment at about 135°C and used as an adhesive fiber containing polyethylene as an adhesive component, and a single synthetic fiber made of polypropylene or polyethylene terephthalate may be used as a non-adhesive fiber.

[0017] When some or all of the synthetic fibers are adhesive fibers and the adhesive fibers bond the fibers together, the mechanical properties of the nonwoven fabric are further improved, and the use of the adhesive fibers makes it easier to obtain a stress index at MD5% elongation in the above range. Therefore, adhesive fibers are preferably used in this embodiment. However, even if the adhesive fibers are not included, it is possible to achieve a stress index at MD5% elongation in the above range by appropriately selecting the configurations of the fiber layer a and the intermediate fiber layer and appropriately selecting the manufacturing conditions of the nonwoven fabric.

[0018] When the synthetic fiber is contained in the fiber layer a, the synthetic fiber may be one or more types of synthetic fiber selected from synthetic fibers containing biomass raw materials, biodegradable synthetic fibers, and synthetic fibers containing recycled raw materials. Such synthetic fibers are preferably used together with hydrophilic cellulose fibers from the viewpoint of the SDGs.

[0019] The fiber layer a may also contain, as other fibers, water-repellent cellulose fibers, natural fibers that are not hydrophilic cellulose fibers, etc. Here, the water-repellent cellulose fibers refer to cellulose fibers that are inherently hydrophilic but have been artificially imparted with water repellency, as described below.

[0020] In this embodiment, either one or both of the first and second fiber layers are fiber layers a. When only one of the fiber layers is fiber layer a, the other fiber layer may be a fiber layer containing hydrophilic cellulose fibers at a ratio of less than 50%, a fiber layer composed only of synthetic fibers, or a fiber layer containing natural fibers other than cellulose fibers.

[0021] When both the first and second fiber layers are fiber layers a, the two fiber layers may be the same or different in terms of the type of fiber, the fiber mixing ratio, the manufacturing form of the fiber layer (type of fiber web), etc. For example, by changing the fiber ratio of the two fiber layers, the surfaces of the two fiber layers can be used for different purposes (one surface for wiping flooring surfaces and the other surface for wiping bathroom floors).

[0022] In this embodiment, the intermediate fiber layer is a fiber layer containing 50% or more by mass of hydrophilic cellulose fibers and / or a wetlaid nonwoven fabric composed of short fibers having a fiber length of 20 mm or less, and is located between the first fiber layer and the second fiber layer.

[0023] When the intermediate fibrous layer is a fibrous layer containing hydrophilic cellulose fibers, the proportion of hydrophilic cellulose fibers may be particularly 60% by mass or more, more particularly 70% by mass or more. The intermediate fibrous layer may be composed of only hydrophilic cellulose fibers. The intermediate fiber layer contains hydrophilic cellulose fibers, and together with the fiber layer a containing hydrophilic cellulose fibers, when the nonwoven fabric is impregnated with liquid, it becomes easy to impregnate the nonwoven fabric with a sufficient amount of liquid. The hydrophilic cellulose fibers in the intermediate fiber layer also promote entanglement of the fibers between the first and second fiber layers and the intermediate fiber layer when the fibers are entangled with high-pressure water flow, thereby enhancing the mechanical strength of the nonwoven fabric. Therefore, if the ratio of hydrophilic cellulose fibers in the intermediate fiber layer is small, depending on the application, the wettability may be insufficient or the wiping ability of liquid may be reduced, and the stress index at MD5% elongation in the above range may not be obtained.

[0024] The intermediate fiber layer containing 50% by mass or more of hydrophilic cellulose fibers may be, for example, a meltblown nonwoven fabric or a long fiber nonwoven fabric (also called a spunbonded nonwoven fabric), or it may be an air-through nonwoven fabric or a point-bonded nonwoven fabric formed from short fibers, or a wet-laid nonwoven fabric.

[0025] When the intermediate fiber layer is a wetlaid nonwoven fabric made of short fibers with a fiber length of 20 mm or less, the wetlaid nonwoven fabric is easily entangled with the fiber layers above and below when the fibers are entangled by the injection of a high-pressure fluid flow, and is likely to give a nonwoven fabric having a stress index at 5% elongation in MD within the above range. In addition, since there is little difference in the mechanical properties in the MD and CD directions, the wetlaid nonwoven fabric is also likely to give a nonwoven fabric with a large stress at 5% elongation in the CD direction.

[0026] In this embodiment, the intermediate fiber layer may be a wet nonwoven fabric containing 50% by mass or more of hydrophilic cellulose fibers. A wet nonwoven fabric containing hydrophilic cellulose fibers is preferably used to set the stress at 5% elongation of the final nonwoven fabric within the above range. In addition, a wet nonwoven fabric containing hydrophilic cellulose fibers has excellent water absorption and can hold a large amount of liquid. Therefore, when the nonwoven fabric of this embodiment is impregnated with liquid and used as a wet object wiper, the wet nonwoven fabric made of pulp functions as a tank for storing liquid (for example, a cleaning liquid contained in the wet wipe) and can perform the function of supplying liquid to the wiping surface for a long period of time during wiping, or can hold the liquid wiped off.

[0027] Alternatively, the intermediate fiber layer may be a wet-laid nonwoven fabric (or tissue) made of pulp. In a wet-laid nonwoven fabric made of pulp, the fibers are not tightly entangled with each other, so that when the fibers are entangled with each other by a high-pressure water flow, the fibers can be well entangled with the fibers constituting the fiber layer a, improving the mechanical strength of the entire nonwoven fabric. As a result, it is easy to set the stress index at MD5% elongation of the obtained nonwoven fabric within the above range. In addition, since pulp is generally derived from wood or natural fibers, a wet-laid nonwoven fabric made of pulp contributes to improving the water absorbency of the nonwoven fabric.

[0028] In the nonwoven fabric of this embodiment, the basis weight of the fiber layer a is, for example, 10 g / m 2 More than 70g / m 2 It may have a basis weight of 10 g / m 2 More than 65g / m 2 and more particularly 15 g / m 2 More than 60g / m 2 and more particularly 20 g / m 2 More than 55g / m 2 When either the first fiber layer or the second fiber layer is not the fiber layer a, the fiber layer other than the fiber layer a may have a basis weight of, for example, 10 g / m 2 More than 65g / m 2 It may have a basis weight of 15 g / m 2 More than 60g / m2 and more particularly 20 g / m 2 More than 55g / m 2 It may have the following basis weight:

[0029] When the fiber layer a is present as a first fiber layer and a second fiber layer, the first fiber layer and the second fiber layer each have a fiber thickness of, for example, 10 g / m 2 More than 50g / m 2 It may have a basis weight of 12.5 g / m 2 More than 47.5g / m 2 and more particularly 15 g / m 2 More than 45g / m 2 and more particularly 17.5 g / m 2 More than 40g / m 2 It may have the following basis weight:

[0030] The intermediate fiber layer constituting the nonwoven fabric together with the first and second fiber layers has a fiber density of, for example, 5 g / m 2 More than 50g / m 2 It may have a basis weight of 6 g / m 2 More than 45g / m 2 and more particularly 7 g / m 2 More than 40g / m 2 and more particularly 8 g / m 2 More than 35g / m 2 It may have the following basis weight:

[0031] In a nonwoven fabric having a structure including a first and second fiber layer and an intermediate fiber layer, when the basis weight of the entire nonwoven fabric is taken as 1, the ratio of the basis weight of the intermediate fiber layer to this (intermediate fiber layer / entire nonwoven fabric) may be, for example, 0.05 to 1, particularly 0.10 to 0.80, more particularly 0.15 to 0.60. If the ratio of the intermediate fiber layer to the nonwoven fabric is too large, it may hinder entanglement with the first and second fiber layers, and the first or second fiber layer may peel off when used as a wiper. On the other hand, if the ratio of the basis weight of the intermediate fiber layer is too small, the stress index of the nonwoven fabric at MD5% elongation may be outside the above range.

[0032] The basis weight of the entire nonwoven fabric of this embodiment may be appropriately selected depending on the application, etc. The nonwoven fabric of this embodiment has a basis weight of, for example, 30 g / m 2 More than 100g / m 2 It may have a basis weight of 35 g / m 2 More than 95g / m 2 and more particularly 40 g / m 2 More than 90g / m 2 and more particularly 45 g / m 2 More than 85g / m 2 It may have the following basis weight:

[0033] The nonwoven fabric of this embodiment may have a striped pattern in which parts with different degrees of fiber entanglement, i.e., highly entangled parts and less entangled parts, are alternately formed in the CD direction by carrying out a specific hydroentanglement treatment as described below. The highly entangled parts are parts in which the fibers are more closely entangled with each other, and contribute to increasing the strength of the nonwoven fabric to a certain extent, while the less entangled parts are parts in which the fibers are less entangled with each other, and therefore have a relatively high degree of fiber freedom, and contribute to increasing the bulk of the nonwoven fabric to a certain extent.

[0034] In the nonwoven fabric of this embodiment, the low entanglement portion may have a width of 2 mm or more and 50 mm or less, and by having such a low entanglement portion, the degree of freedom of the fibers can be relatively high in the nonwoven fabric as a whole. The width of the low entanglement portion may be particularly 3 mm or more and 25 mm or less, more particularly 4 mm or more and 20 mm or less, even more particularly 6 mm or more and 15 mm or less, and even more particularly 8 mm or more and 12 mm or less. The width of the highly entangled portion may be, for example, 2 mm or more and 50 mm or less, especially 3 mm or more and 25 mm or less, more particularly 4 mm or more and 20 mm or less, and even more particularly 8 mm or more and 12 mm or less. Alternatively, the highly entangled portion may be a linear portion having a width smaller than 2 mm. In a nonwoven fabric having such a pattern, it is believed that the highly entangled portions play a role in increasing the mechanical strength of the wiper, while the less entangled portions play a role in wiping off and collecting dirt.

[0035] As described later, by selecting a support used when forming the highly entangled parts, low density regions can be regularly formed in the highly entangled parts to form a pattern. A nonwoven fabric having a pattern formed in the highly entangled parts exhibits a design effect. In addition, by forming low density regions in the highly entangled parts, the low density regions can improve the dirt collection ability.

[0036] The low density area is, for example, 0.03 mm 2 ~20mm 2 and in particular may have an area of ​​0.1 mm 2 ~10mm 2 and more particularly, 0.7 mm 2 ~5.0mm 2 The area of ​​the low-density region may be 1 / 100 or more. Alternatively, the pattern formed in the highly entangled portion may be a herringbone pattern formed by the low-density region. If the low-density region is too small, the low-density region may not be sufficiently recognized, and the design effect may not be fully exhibited. If the low-density region is too large, the nonwoven fabric may be easily deformed or damaged, such as stretched, twisted, or torn, and the handleability may be reduced. If the low-density region is too large, it may be difficult to recognize the low-density region, and the design effect may not be fully exhibited.

[0037] The low density regions may be open pores where no fibers are present, or may not be open pores, or a single nonwoven fabric may have both open pores and non-open low density regions to form a pattern.

[0038] In the nonwoven fabric of this embodiment, if necessary, an embossing roll having convex portions on its surface may be used to form concave portions on the surface of the nonwoven fabric in a shape corresponding to the convex portions of the embossing roll. The shape of the convex portions may be circular, square, elliptical, diamond, or rectangular when viewed from above, and may be trapezoidal, square, or curved when viewed from the side. The concave portions formed on the nonwoven fabric can appropriately adjust the frictional force between the surface of the nonwoven fabric and the object to be wiped. The concave portions may be further formed on a nonwoven fabric having a pattern formed by highly entangled portions and less entangled portions, or may be formed on a nonwoven fabric without a pattern (i.e., a nonwoven fabric having only fluid marks formed as streaky concaves and convexes by the injection of a fluid flow).

[0039] The nonwoven fabric of this embodiment has a stress index at 5% elongation in MD of 0.150 or more, which is the value obtained by dividing the stress at 5% elongation in MD when dry by the basis weight, and / or a stress index at 5% elongation in MD of 0.050 or more, which is the value obtained by dividing the stress at 5% elongation in MD when wet by the basis weight.

[0040] The stress index at MD5% elongation when dry may be particularly 0.160 or more, more particularly 0.170 or more. The stress index at MD5% elongation when dry may be 0.900 or less, particularly 0.890 or less, more particularly 0.880 or less. The stress index at MD 5% elongation when wet may be particularly 0.050 or more, more particularly 0.055 or more, and the stress index at MD 5% elongation may be 0.300 or less, more particularly 0.295 or less.

[0041] The nonwoven fabric of this embodiment has a stress index at MD 5% elongation when dry of 0.150 or more and / or a stress index at MD 5% elongation when wet of 0.050 or more, thereby suppressing twisting and stretching during wiping when impregnated with liquid and used as a wiper, and preventing the inter-fiber voids from expanding due to twisting and stretching, which would cause the captured dirt to fall off.

[0042] Furthermore, when a nonwoven fabric having a stress index at MD5% elongation when dry and / or a stress index at MD5% elongation when wet equal to or greater than the above-mentioned predetermined value is manufactured by a method of entangling fibers with a high-pressure fluid flow (particularly a high-pressure water flow), the injection marks of the fluid flow are formed as streaky irregularities more clearly (i.e., with larger steps). It is presumed that these irregularities contribute to scraping or entangling dirt, and, together with the high stress index at MD5% elongation of the nonwoven fabric, improve the dirt collection ability of the nonwoven fabric.

[0043] The nonwoven fabric of this embodiment may have a stress at 5% elongation in the MD direction when dry of, for example, 10 N / 5 cm or more, particularly 10.5 N / 5 cm or more and 40.0 N / 5 cm or less, more particularly 11.0 N / 5 cm or more and 39.5 N / 5 cm or less. The nonwoven fabric of this embodiment may have a stress at 5% elongation in the CD direction when dry of, for example, 0.1 N / 5 cm or more and 7.0 N / 5 cm or less, particularly 0.2 N / 5 cm or more and 6.8 N / 5 cm or less, more particularly 0.3 N / 5 cm or more and 6.5 N / 5 cm or less. If the stress at 5% elongation in the MD direction when dry is too low, even if the MD 5% elongation stress index obtained by dividing this by the basis weight satisfies 0.150 or more, it may be difficult to handle during product processing. Similarly, if the stress at 5% elongation in the CD direction is too low, it may be difficult to handle during product processing. If the stress at 5% elongation in the CD direction is too low, the product will be difficult to handle during processing. If the stress at 5% elongation in the MD or CD direction during drying is too high, the fibers will not move easily during wiping, and the dirt collection ability may decrease due to the movement of the fibers.

[0044] The nonwoven fabric of this embodiment may have a tensile strength in the MD direction when dry of, for example, 30N / 5cm or more and 200N / 5cm or less, particularly 35N / 5cm or more and 195N / 5cm or less, and more particularly 40N / 5cm or more and 190N / 5cm or less. If the tensile strength in the MD direction when dry is too low, the fabric may break during product processing. If the tensile strength in the MD direction when dry is too high, the nonwoven fabric tends to be rigid. If a rigid nonwoven fabric is used as a wiper, the target object may be scratched.

[0045] The nonwoven fabric of this embodiment may have a tensile strength in the CD direction when dry of, for example, 3 N / 5 cm or more and 100 N / 5 cm or less, particularly 4 N / 5 cm or more and 95 N / 5 cm or less, and more particularly 5 N / 5 cm or more and 90 N / 5 cm or less. If the tensile strength in the CD direction when dry is too low, the nonwoven fabric may break during use. If the tensile strength in the CD direction when dry is too high, the nonwoven fabric tends to be rigid. If a rigid nonwoven fabric is used as a wiper, the target object may be scratched.

[0046] The nonwoven fabric of this embodiment may have a CD elongation percentage when dry of, for example, 60% or more and 200% or less, particularly 65% ​​or more and 195% or less, and more particularly 70% or more and 190% or less. If the CD elongation percentage when dry is too low, the fibers will not move easily when used as a wiper, and the interfiber voids will not deform easily, making it difficult to capture various types of dirt, and the collection performance may decrease. If the CD elongation percentage when dry is too high, the sheet will tend to elongate greatly due to the influence of external pressure applied to the sheet when used as a wiper, and dirt that has once been collected may fall off.

[0047] The nonwoven fabric of this embodiment may have a tensile strength in the MD direction when wet of, for example, 10 N / 5 cm or more and 110 N / 5 cm or less, particularly 12.5 N / 5 cm or more and 107.5 N / 5 cm or less, more particularly 15 N / 5 cm or more and 105 N / 5 cm or less. If the tensile strength in the MD direction when wet is too low, the nonwoven fabric may break during use. If the tensile strength in the MD direction when wet is too high, the nonwoven fabric tends to be rigid. If a rigid nonwoven fabric is used as a wiper, the target object may be scratched.

[0048] The nonwoven fabric of this embodiment may have a tensile strength in the CD direction when wet of, for example, 3 N / 5 cm or more and 100 N / 5 cm or less, particularly 4 N / 5 cm or more and 95 N / 5 cm or less, and more particularly 5 N / 5 cm or more and 90 N / 5 cm or less. If the tensile strength in the CD direction when dry is too low, the nonwoven fabric may break during use. If the tensile strength in the CD direction when dry is too high, the nonwoven fabric tends to be rigid. If a rigid nonwoven fabric is used as a wiper, the target object may be scratched.

[0049] The nonwoven fabric of this embodiment may have a CD elongation percentage when wet of, for example, 65% or more and 150% or less, particularly 70% or more and 145% or less, and more particularly 75% or more and 140% or less. If the CD elongation percentage when wet is too low, the fibers will not move easily when used as a wiper, and the interfiber voids will not deform easily, making it difficult to capture various types of dirt, and the collection performance may decrease. If the CD elongation percentage when wet is too high, the sheet is likely to elongate significantly due to the influence of external pressure applied to the sheet when used as a wiper, and dirt that has been collected may fall off.

[0050] The nonwoven fabric of this embodiment may be a nonwoven fabric having a stress index at 5% elongation in CD of 0.010 or more, which is the value obtained by dividing the stress at 5% elongation in CD when dry by the basis weight, and / or a stress index at 5% elongation in CD of 0.0035 or more, which is the value obtained by dividing the stress at 5% elongation in CD when wet by the basis weight.

[0051] The stress index at 5% elongation on CD when dry may be 0.010 or more, more particularly 0.012 or more. The stress index at 5% elongation on CD when dry may be 0.110 or less, more particularly 0.105 or less, more particularly 0.100 or less. The stress index at 5% elongation on CD when wet may be 0.0035 or more, more particularly 0.0040 or more. The stress index at 5% elongation on CD when wet may be 0.040 or less, more particularly 0.035 or less, more particularly 0.030 or less.

[0052] When the stress index at CD 5% elongation in the dry and / or wet state is within the above range, the fibers and the nonwoven fabric are appropriately deformed by the stress applied to the nonwoven fabric during the wiping operation, making it easier for dirt to be absorbed into the nonwoven fabric. In addition, the deformed state of the nonwoven fabric is maintained to such an extent that the absorbed dirt does not fall off even when the wiping operation is continued, and dirt once absorbed is unlikely to fall off. Furthermore, when the nonwoven fabric is removed from the packaging of the wiper product or when it is attached to a jig for use, the nonwoven fabric is unlikely to deform, making it easy to handle.

[0053] Next, the fibers constituting the nonwoven fabric according to the present disclosure will be described. (hydrophilic cellulose fiber) Cellulose fibers are inherently hydrophilic, and in that sense the term "hydrophilic" is unnecessary, but to distinguish them from water-repellent cellulose fibers, cellulose fibers to which water repellency has not been imparted are referred to as "hydrophilic cellulose fibers" herein. More specifically, cellulose fibers having a sedimentation rate of 60 seconds or less when measured by the following method are referred to as hydrophilic cellulose fibers. The sedimentation rate of the hydrophilic cellulose fibers used in this embodiment may be, for example, 50 seconds or less, particularly 45 seconds or less, and more particularly 30 seconds or less.

[0054] <Sedimentation velocity measurement> In accordance with the standard for medical gauze and medical absorbent cotton, Yakushokuki-hatsu No. 0630001, measure the sedimentation velocity (6(1)Ka) using the following method.

[0055] Fibers before nonwoven fabric production or fibers taken from nonwoven fabric are defibrated using a carding machine to prepare a fiber aggregate. 0.3 g of this fiber aggregate is rolled into a ball with a diameter of 2 cm or less and gently dropped into water at a depth of 200 mm from a height of 12 mm above the water surface at a temperature of 24 to 26°C. The time it takes for the fiber aggregate to sink below the water surface after being dropped is defined as the settling velocity of the fiber.

[0056] If the fibers cannot be defibrated in a carding machine (e.g., if the fibers are short), 0.3 g of the collected fibers may be rolled up and dropped into water. Alternatively, if the fibers are already in the form of a fiber aggregate (e.g., a wet-laid nonwoven fabric or an air-laid nonwoven fabric) and it is difficult to defibrate them in a carding machine, 0.3 g of the nonwoven fabric cut into pieces 1 cm x 1 cm in size may be dropped into water.

[0057] The type of cellulose fiber is not particularly limited. The cellulose fiber includes the following: (1) Natural fibers derived from plants such as cotton, flax, flax, ramie, jute, banana, bamboo, kenaf, shell ginger, hemp and kapok; (2) Solvent-spun cellulose fibers such as viscose-derived rayon and polynosic, cupra-derived cuprammonium-derived cupramide, and solvent-spun Tencel® and Lyocell, as well as other regenerated fibers; (3) Cellulose fibers obtained by melt spinning; (4) Semi-synthetic fibers such as acetate fibers; and (5) Pulp, such as mechanical pulp, recycled pulp and chemical pulp

[0058] The hydrophilic cellulose fiber may be a regenerated fiber. Regenerated fibers are preferably used because the fineness can be easily adjusted and the variation is small. Among regenerated fibers, viscose rayon is particularly preferably used because it is easy to reduce the bending resistance of the nonwoven fabric and makes the nonwoven fabric soft. Viscose rayon has a chrysanthemum-like cross-sectional shape, and the unevenness of the cross-section is observed as streaky unevenness extending in the length direction on the fiber surface. These unevennesses provide interfiber voids suitable for collecting dirt, and also enable dirt to be taken into the recesses themselves.

[0059] When a solvent-spun cellulose fiber such as lyocell is used as the hydrophilic cellulose fiber, the fiber strength is less reduced when wet, and the mechanical properties of the nonwoven fabric when wet can be improved.

[0060] The fineness of the hydrophilic cellulose fibers may be, for example, 0.2 dtex or more and 8.0 dtex or less, particularly 0.3 dtex or more and 7.0 dtex or less, more particularly 0.4 dtex or more and 6.0 dtex or less, and even more particularly 0.6 dtex or more and 5.0 dtex or less. If the fineness of the hydrophilic cellulose fibers is too small, fiber lumps (neps) are likely to occur in the nonwoven fabric, and if it is too large, the touch of the nonwoven fabric may be deteriorated. The fineness of the hydrophilic cellulose fibers is not limited to these ranges. In particular, when natural fibers are used, it is difficult to adjust the fineness, so that fibers with finenesses outside the above ranges may be used. For example, pulp is generally provided in a form in which fibers with a fineness of about 1.0 dtex or more and 4.0 dtex or less and a fiber length of about 0.8 mm or more and 4.5 mm or less are mixed, and this form may be used as it is.

[0061] The fiber length of the hydrophilic cellulose fibers used in the fiber layer a and the intermediate fiber layer is not particularly limited, and may be appropriately selected according to the material, its manufacturing method, the manufacturing method of each fiber layer, the manufacturing method of the nonwoven fabric, etc. The hydrophilic cellulose fibers are, for example, short fibers. When the fiber layer a is made from a card web, the fiber length of the hydrophilic cellulose fibers may be 100 mm or less, 75 mm or less, or 65 mm or less. The fiber length of the hydrophilic cellulose fibers of the above short fibers may be 10 mm or more, 20 mm or more, or 30 mm or more. In the above case, in one embodiment, the fiber length of the hydrophilic cellulose fibers may be 10 mm or more and 100 mm or less. When the fiber layer a is made from an airlaid web, the fiber length of the hydrophilic cellulose fibers may be 2 mm or more and 20 mm or less.

[0062] As described above, the intermediate fiber layer may be a wet nonwoven fabric, and in this case, the fiber length of the hydrophilic cellulose fibers constituting the wet nonwoven fabric may be 20 mm or less, or less than 10 mm. The fiber length of the hydrophilic cellulose fibers constituting the wet nonwoven fabric may be 1 mm or more. When the intermediate fiber layer contains a certain proportion or more of short hydrophilic cellulose fibers, the intermediate fiber layer plays a "tank-like" role to hold liquid when the nonwoven fabric is used as a wet object wiper, making it possible to release the liquid little by little over a long period of time. Examples of hydrophilic cellulose fibers with fiber lengths of less than 10 mm include pulps such as mechanical pulp, regenerated pulp, and chemical pulp, as well as regenerated fibers, melt-spun cellulose fibers, and semi-synthetic fibers, which are relatively easy to cut to the desired fiber length during the manufacturing process.

[0063] In this embodiment, pulp is preferably used as the hydrophilic cellulose fiber contained in the intermediate fiber layer. The pulp may be one produced by a conventional method using softwood or hardwood. The pulp may also be one produced by a conventional method using non-wood materials such as cotton linters, kenaf, bagasse, bamboo, straw, esparto, and seaweed. Pulp is easily accepted by consumers because of its proven use as a material for sanitary products and daily necessities, and is also biodegradable, so it is preferably used as a material for products that are discarded after use (e.g., disposable wipers). Furthermore, pulp made from wood is well entangled with the hydrophilic cellulose fiber of the fiber layer a when the fibers are entangled with each other by a high-pressure water flow as described below, and is likely to improve the stress index at MD5% elongation.

[0064] (Other fibers) The nonwoven fabric of this embodiment may contain other fibers other than the hydrophilic cellulose fibers. The other fibers are, for example, fibers constituting the fiber layer a together with the hydrophilic cellulose fibers, or fibers constituting the intermediate fiber layer together with the hydrophilic cellulose fibers, or fibers constituting the first fiber layer or the second fiber layer other than the fiber layer a. Alternatively, when the intermediate fiber layer is a wet-laid nonwoven fabric, the wet-laid nonwoven fabric may be composed only of other fibers. The other fibers are not particularly limited. The other fibers may be water-repellent cellulose fibers obtained by imparting water repellency to cellulose fibers, synthetic fibers, or natural fibers. Two or more types of fibers may be used as the other fibers. Synthetic fibers will be described below as an example of the other fibers.

[0065] [Synthetic fibers] The synthetic fibers may be made of one or more thermoplastic resins selected from the following: polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and copolymers thereof; polyolefin-based 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-vinyl alcohol copolymers, and ethylene-vinyl acetate copolymers; polyamide-based resins such as nylon 6, nylon 12, and nylon 66; acrylic-based resins; engineering plastics such as polycarbonate, polyacetal, polystyrene, and cyclic polyolefins, and elastomers thereof. Of these, biodegradable resins such as polylactic acid and polybutylene succinate are preferably used when SDGs are emphasized.

[0066] Alternatively, the synthetic fiber may be a synthetic fiber containing a biomass raw material. Synthetic fibers containing biomass raw materials include, for example, synthetic fibers containing biopolypropylene (also called bioPP), biopolyethylene (also called bioPE), biopolyethylene terephthalate (also called bioPET), biopolytrimethylene terephthalate (also called bioPTT), biopolycarbonate (also called bioPC), biopolyurethane (also called bioPU), biopolyamide 11 (also called bioPA11), biopolyamide 1010 (also called bioPA1010), biopolyamide 610 (also called bioPA610), biopolyamide MXD10 (also called bioMXD10), biopolyamide 11T (also called bioPA11T), etc., and more specifically, synthetic fibers manufactured by melt spinning such biomass raw materials. Synthetic fibers containing biomass raw materials are also preferably used when SDGs are emphasized.

[0067] Alternatively, the synthetic fiber may be a synthetic fiber containing recycled resin raw materials. Examples of synthetic fibers containing recycled resin raw materials include recycled (regenerated) polypropylene (also called recycled (regenerated) PP), recycled (regenerated) polyethylene terephthalate (also called recycled (regenerated) PET), recycled (regenerated) nylon, etc. Synthetic fibers containing recycled resin raw materials are also preferably used when SDGs are emphasized.

[0068] In the following, when the resin is provided as a biomass raw material or a recycled resin raw material, the resin specifically mentioned also refers to the resin made from these raw materials. For example, when the term "polypropylene single fiber" is used, it includes not only a single fiber made from a normal polypropylene raw material, but also a single fiber made from biopolypropylene and a single fiber made from recycled (regenerated) polypropylene.

[0069] The synthetic fibers may be single fibers whose cross sections are made of a single component (also called "single section") and / or composite fibers whose cross sections are made of multiple components (also called "sections"). The composite fibers may be, for example, concentric or eccentric sheath-core composite fibers, islands-in-the-sea composite fibers, side-by-side composite fibers, or splittable composite fibers. The cross sections of the fibers may be circular or noncircular, and examples of noncircular shapes include elliptical, Y-shaped, X-shaped, well-shaped, multi-lobal, polygonal, star-shaped, and the like. The synthetic fibers may also have a hollow cross section. In both the case of single fibers and composite fibers, each section constituting the fiber may be made of one type of resin or a mixture of two or more types of resin.

[0070] When the synthetic fiber is a monofilament, the monofilament may be made of one or more resins selected from the group consisting of the polyolefin resin, the polyester resin, the polyamide resin, and the acrylic resin. More specifically, a monofilament of polyethylene, a monofilament of polypropylene, a monofilament of polyethylene terephthalate, etc. may be used.

[0071] When the synthetic fiber is a composite fiber, two or more components may be arranged so that the thermoplastic resin with the lowest melting point constitutes part of the fiber surface. In this case, when heat is applied under conditions in which the component consisting of the thermoplastic resin with the lowest melting point (hereinafter referred to as the "low melting point component") melts or softens in the process of producing a nonwoven fabric, the low melting point component becomes the adhesive component. The combination of resins (first / second) constituting the composite fiber consisting of a first component which is a thermoplastic resin with a higher melting point and a second component which is a thermoplastic resin with a lower melting point is, for example, a combination of a polyester-based resin and a polyolefin-based resin such as polyethylene terephthalate / polyethylene, polyethylene terephthalate / polypropylene, and polyethylene terephthalate / propylene copolymer, a combination of two types of polyolefin-based thermoplastic resins such as polypropylene / polyethylene, and polypropylene / propylene copolymer, and a combination of two types of polyester-based resins with different melting points.

[0072] Alternatively, the first and second components may be a combination of biodegradable resins, and such a combination can increase the proportion of biodegradable fibers in the nonwoven fabric. Specifically, the synthetic fibers can be made biodegradable by using polylactic acid as the first component and polybutylene succinate as the second component.

[0073] The thermoplastic resins exemplified as components of the single fiber or composite fiber may contain other components as long as they contain 50% by mass or more of the specifically indicated thermoplastic resin. The specifically indicated thermoplastic resin may be contained in an amount of 80% by mass or more, 90% by mass or more, or the components may consist essentially of the specifically indicated thermoplastic resin. The term "substantially" is used here in consideration of the fact that thermoplastic resins usually contain various additives, etc. For example, in the combination of polyethylene terephthalate / polyethylene, "polyethylene" may contain other thermoplastic resins and additives, etc., as long as it contains 50% by mass or more of polyethylene. This also applies to the following examples.

[0074] When the synthetic fiber is a concentric or eccentric core-sheath type composite fiber in which a thermoplastic resin having a higher melting point constitutes the core component as a first component and a thermoplastic resin having a lower melting point constitutes the sheath component as a second component, the core / sheath combination may be, for example, polypropylene / polyethylene, polypropylene / propylene-ethylene copolymer, polypropylene / propylene-butene-1-ethylene copolymer, polylactic acid / polybutylene succinate, 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). These resin combinations may also be used in splittable composite fibers.

[0075] In the case of core-sheath type composite fibers, the volume ratio of the core component to the sheath component (core component:sheath component) is preferably 80:20 to 20:80, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60.

[0076] In the case of splittable conjugate fibers, the ratio of the two components (first:second) is preferably 80:20 to 20:80 by volume, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60. In the case of splittable conjugate fibers, the number of divisions (i.e., the number of sections in the conjugate fiber) may be, for example, 4 or more and 32 or less, particularly 4 or more and 20 or less, and more particularly 6 or more and 10 or less.

[0077] In this embodiment, the synthetic fibers preferably used are core-sheath type composite fibers (concentric or eccentric) in which the combination of the first component / second component is polylactic acid / polybutylene succinate, polyethylene terephthalate / copolymer polyester, polypropylene / polyethylene, or polyethylene terephthalate / polyethylene. When used as adhesive fibers, these fibers exhibit adhesiveness at relatively low temperatures (110°C or higher and 130°C or lower) and make the texture of the nonwoven fabric soft after bonding.

[0078] The fineness of the synthetic fibers may be, for example, 1.0 dtex or more and 8.0 dtex or less, particularly 1.1 dtex or more and 7.5 dtex or less, more particularly 1.2 dtex or more and 6.0 dtex or less, and even more particularly 1.4 dtex or more and 5.0 dtex or less. If the fineness of the synthetic fibers is too small, the strength of the nonwoven fabric is low, and the nonwoven fabric may easily stretch, and the fiber density of the surface of the nonwoven fabric may increase, making it easy for clogging with dirt to occur, and the dirt collection ability may decrease. If the fineness of the synthetic fibers is too large, the touch of the nonwoven fabric may become hard. If the nonwoven fabric is prone to stretching, for example, when the nonwoven fabric is attached to a jig for wiping work, sagging or wrinkles may occur when attached to the jig, and the fiber density of the surface of the nonwoven fabric may decrease, causing dirt that has once been collected to fall off.

[0079] When the synthetic fiber is the adhesive fiber, the fineness of the adhesive fiber may be 0.8 dtex or more and 6.4 dtex or less, in particular 1.0 dtex or more and 5.6 dtex or less, more particularly 1.2 dtex or more and 4.4 dtex or less, and even more particularly 1.4 dtex or more and 2.0 dtex or less. If the fineness of the adhesive fiber is too small, the number of bonding points with the fiber increases too much, decreasing the degree of freedom of the fiber and / or increasing the fiber density, which may lead to a decrease in dirt collection ability.If the fineness of the adhesive fiber is too large, the texture becomes hard, the nonwoven fabric itself becomes difficult to bend, the ability to follow the object to be wiped decreases, and the dirt collection ability may tend to decrease.

[0080] In particular, when the synthetic fiber is a splittable conjugate fiber, the splittable conjugate fiber may have a fineness of 1.0 dtex or more and 4.0 dtex or less before splitting, and may give a synthetic fiber of 0.1 dtex or more and less than 1.0 dtex after splitting.

[0081] The fiber length of the synthetic fibers is not particularly limited and may be appropriately selected depending on the manufacturing method of the nonwoven fabric. For example, in the manufacture of the nonwoven fabric, when the fiber layer is manufactured by preparing a carded web, the synthetic fibers may be short fibers. The fiber length of the short fibers may be, for example, 10 mm or more and 100 mm or less, particularly 20 mm or more and 75 mm or less, and more particularly 30 mm or more and 65 mm or less. Alternatively, when the fiber layer is manufactured by an air-laying method, the fiber length may be, for example, 2 mm or more and 20 mm or less. Alternatively, when the fiber layer is a wet-laid nonwoven fabric, the fiber length may be, for example, 20 mm or less.

[0082] Synthetic fibers are generally hydrophobic and have, for example, an official moisture regain of less than 5%. In this embodiment, the synthetic fibers may be subjected to a hydrophilization treatment. Examples of the hydrophilization treatment include corona discharge treatment, sulfonation treatment, graft polymerization treatment, kneading a hydrophilizing agent into the fibers, and application of a durable oil agent. By subjecting the synthetic fibers to a hydrophilization treatment, entanglement of the fibers is promoted, particularly when a nonwoven fabric is produced by entangling the fibers with a high-pressure water flow, and it becomes easy to obtain a nonwoven fabric having a stress index of 0.150 or more at MD5% elongation in a dry state and / or a stress index of 0.050 or more at MD5% elongation in a wet state.

[0083] Although the synthetic fibers have been described as the other fibers in the above, the other fibers are not limited thereto. The nonwoven fabric of the present embodiment may include, as the other fibers, for example, water-repellent cellulose fibers or natural fibers such as silk and wool.

[0084] Next, a method for producing the nonwoven fabric of this embodiment will be described. The nonwoven fabric of this embodiment is, for example, Preparing a laminated web having an intermediate fibrous web disposed between a first fibrous web and a second fibrous web; subjecting the laminated web to a high pressure fluid stream entanglement treatment; Including, one or both of the first fiber web and the second fiber web is a fiber web A containing 50% by mass or more of hydrophilic cellulose fibers, The intermediate fiber web is a fiber web and / or a wet-laid nonwoven fabric containing 50% by mass or more of hydrophilic cellulose fibers, The entanglement treatment is carried out so that the total energy TE of the water stream sprayed onto the laminated web is 0.11 khw / kg / m or more and 1.20 khw / kg / m or less. It is produced by the method.

[0085] The types and basis weights of the fibers contained in the first fiber web, the second fiber web, the intermediate fiber web, and the fiber web A are the same as those described in relation to the first fiber layer, the second fiber layer, the intermediate fiber layer, and the fiber layer a, and therefore will not be repeated here.

[0086] The first and second fiber webs can be produced by a known method. The form of each fiber web may be any one selected from, for example, a parallel web, a cross web, a carded web such as a semi-random web or a random web, an air-laid web, and a wet-laid paper web. The forms of the first and second fiber webs may be different from each other. When the first and second fiber webs are carded webs, particularly parallel webs, more fibers are oriented in the MD direction, so that the mechanical properties in the MD direction are easily improved, and it is easier to set the stress at MD 5% elongation in the above range.

[0087] The form of the intermediate fiber web is also not limited, and may be any of the forms exemplified above in relation to the first fiber web and the second fiber web. When the intermediate fiber web is made of pulp, the intermediate fiber web may be a wet-laid papermaking web or an airlaid web. In addition, the intermediate fiber web may be, for example, a wet-laid papermaking nonwoven fabric, a meltblown nonwoven fabric, or a long-fiber nonwoven fabric that is provided (for example, sold). In this case, strictly speaking, the intermediate fiber web is not in a state where the fibers are only slightly entangled, but is a nonwoven fabric in which the fibers are integrated with each other.

[0088] The laminated fiber web in which the intermediate fiber web is disposed between the first fiber web and the second fiber web is subjected to a process for entangling the fibers. The process for entangling the fibers is, for example, a high-pressure fluid flow (particularly a water flow) entanglement process. In the high-pressure fluid flow process, the high-pressure fluid is, for example, a high-pressure gas such as compressed air, a high-pressure liquid such as high-pressure water, and high-pressure steam. In the manufacture of nonwoven fabrics, a water flow entanglement process using high-pressure water as the high-pressure fluid is often used, and in this embodiment, the water flow entanglement process is preferably used from the viewpoint of ease of implementation. The following describes the entanglement process when high-pressure water (hereinafter also simply referred to as "water flow") is used as the high-pressure fluid.

[0089] The hydroentanglement treatment is carried out by placing the laminated fiber web on a support and spraying a columnar water stream. For example, the support is preferably a plain weave support of 60 mesh or more and 100 mesh or less. The hydroentanglement treatment may be carried out by spraying a water stream with a water pressure of 1 MPa or more and 15 MPa or less on the front and back surfaces of the laminated fiber web 1 to 5 times each from a nozzle having orifices with a hole diameter of 0.05 mm or more and 0.5 mm or less, spaced 0.3 mm or more and 1.5 mm or less. The water pressure is preferably 1 MPa or more and 15 MPa or less, more preferably 3 MPa or more and 10 MPa or less. These conditions are set according to the type / ratio of fibers and the basis weight of the fiber web so that the stress index at MD5% elongation in a dry state and / or the stress index at MD5% elongation in a wet state of the obtained nonwoven fabric are within the above ranges.

[0090] In order to obtain a nonwoven fabric having a stress index at MD 5% elongation in the above range, for example, the total energy of the water jet sprayed onto the laminated fiber web may be adjusted to perform a hydroentanglement treatment. In the method for producing a nonwoven fabric of this embodiment, the total energy TE may be 0.11 khw / kg / m or more and 1.20 khw / kg / m or less, and particularly 0.115 khw / kg / m or more and 1.10 khw / kg / m or less.

[0091] The energy (E) applied to the fibrous web by the jetted water stream is calculated by the following formula: More specifically, the total energy (TE) is calculated by calculating the energy E1 of the water stream jetted on the side of the first fibrous web and the energy E2 of the water stream jetted on the side of the second fibrous web and then calculating their sum.

[0092] E=W×N×T / (M / 1000×U×60) / 1000 E: Energy applied per 1 kg of fiber web per 1 m width per hour (kWh / kg / m) W: Power (W) of the fluid (water in this embodiment) per nozzle orifice N: Number of orifices per 1m width in the nozzle T: Number of injections M: Basis weight of the target for hydroentanglement treatment (g / m 2 ) U: Transport speed (m / min)

[0093] In the above formula, W (the power of the fluid per one nozzle orifice) can be calculated by the following formula. W=P1×(F / 100)×0.163 W: Power of the fluid per nozzle orifice (W) P1: Water pressure (kgf / cm 2 ) F: The flow rate of water discharged from one orifice of the nozzle (cm 3 / min)

[0094] In the above formula, F (the flow rate of water discharged from one orifice of the nozzle) is calculated by the following formula. F=S×V F: The flow rate of water discharged from one orifice of the nozzle (cm 3 / min) S: Area of ​​fluid discharged from one orifice of the nozzle (mm 2 ) V: Flow velocity of the fluid discharged from the nozzle (m / min)

[0095] In the above formula, V (the flow velocity of the fluid discharged from the nozzle) is calculated by the following formula. V = (20 × g × (P1-P2) / ρ) 1 / 2 ×60 V: Flow velocity of the fluid discharged from the nozzle (m / min) g:Gravity acceleration, 9.8m / s 2 P1: Water pressure (kgf / cm 2 ) P2: Atmospheric pressure (kgf / cm 2 ) ρ: Fluid density (g / cm 3 ) Details of the method for determining E etc. are described in Japanese Patent No. 4893256.

[0096] The hydroentanglement treatment may be performed so that parts with different degrees of entanglement, i.e., highly entangled parts and less entangled parts, are arranged alternately in the CD direction, so that a pattern that is recognizable due to the degree of entanglement of the fibers is formed in the obtained nonwoven fabric. Specifically, after hydroentanglement treatment is performed on the entire laminated web using the nozzle exemplified above, a nonwoven fabric having a pattern can be obtained by performing hydroentanglement treatment using a nozzle (hereinafter referred to as a "pattern forming nozzle") in which an orifice assembly part in which fine orifices from which a water stream is ejected are arranged at intervals and an orifice-less part in which no orifice is drilled are arranged alternately.

[0097] The area where the water flow from the orifices of the orifice assembly hits forms a band-shaped highly entangled area, and the area located below the orifice-free area forms a less entangled area. The thickness of the highly entangled area tends to be smaller than that of the less entangled area. Depending on the type of fiber web used and the conditions of the bonding process / entanglement process, when a pattern-forming nozzle is used, it is possible to obtain a nonwoven fabric in which the less entangled areas rise up between the highly entangled areas to form convex areas. In addition, by selecting a support that supports the nonwoven fabric while the water flow is being sprayed using this nozzle, a pattern such as an open hole pattern can be formed in the highly entangled area.

[0098] In the pattern forming nozzle, the orifices may have a hole diameter of, for example, 0.05 mm or more and 0.5 mm or less, and the interval between the orifices in the orifice assembly may be 0.3 mm or more and 1.5 mm or less. The width of the orifice-free portion between the orifice assembly may be, for example, 2 mm or more and 50 mm or less, particularly 3 mm or more and 25 mm or less, more particularly 4 mm or more and 20 mm or less, even more particularly 6 mm or more and 15 mm or less, even more particularly 8 mm or more and 12 mm or less. The width of the orifice assembly may be, for example, 2 mm or more and 50 mm or less, particularly 3 mm or more and 25 mm or less, more particularly 4 mm or more and 20 mm or less, even more particularly 8 mm or more and 12 mm or less. Alternatively, the width of the orifice assembly may be less than 2 mm, in which case the highly entangled portion is formed as a filamentary portion.

[0099] Alternatively, the pattern forming nozzle may be a nozzle in which orifices having the above-mentioned hole diameter are arranged at intervals of 0.3 mm or more and 1.5 mm or less, and a portion equivalent to the orifice-less portion is formed by blocking some of the orifices.

[0100] When a pattern forming nozzle is used, the water pressure of the water stream may be, for example, 1 MPa to 15 MPa, and particularly 3 MPa to 10 MPa.

[0101] The water jet using the pattern-forming nozzle is preferably sprayed once on either side of the laminated web, and more preferably on the side of the fiber layer a. In the hydroentanglement treatment step using the pattern-forming nozzle, it is preferable to perform the hydroentanglement treatment so as to form highly entangled parts and less entangled parts and to clearly define the boundary between them. If the water jet is sprayed multiple times on one side or on both sides, it becomes difficult to form highly entangled parts and less entangled parts. By spraying the water jet using the pattern-forming nozzle on the side of the fiber layer a, a pattern is formed on the side of the wiping surface, and the wiping performance can be improved by the pattern.

[0102] When using a pattern forming nozzle, a pattern can be formed in the highly entangled portion by appropriately selecting the support. The support used when forming a pattern (hereinafter, "pattern forming support") may be a woven fabric, a punched plate-like member, or a spiral net made of natural resin, synthetic resin, or metal. The pattern forming support may have one or more selected from convex portions, concave portions, and openings regularly arranged to have a regular pattern. When such a pattern forming support is used, a regular pattern can be formed by gathering a plurality of regions having a lower density than other portions (hereinafter, "low density regions"). The low density regions may be formed as openings.

[0103] Specifically, the pattern formation support may be, for example, a plain weave fabric, a herringbone weave fabric, a twill weave fabric, or a satin weave fabric woven with monofilaments having a fiber diameter of about 0.1 mm to 1.2 mm at a warp density of 10 threads / inch to 30 threads / inch and a weft density of 10 threads / inch to 30 threads / inch. A support made of a fabric made of relatively thick filaments allows the formation of low-density regions because the intersections of the weft and warp threads become convex parts. When such a fabric is used, the area per low-density region is determined by the thickness of the threads constituting the fabric, and the interval and pitch of the low-density regions are determined by the warp / weft density of the fabric.

[0104] Even when the hydroentanglement treatment is carried out using a pattern forming nozzle, it is preferable to carry out the treatment so that the total energy TE falls within the above range.

[0105] When any one or more of the fiber webs contains adhesive fibers, the laminated fiber webs may be subjected to a bonding treatment before or after the hydroentanglement treatment so that the fibers are bonded together in the resulting nonwoven fabric. The bonding treatment may be a thermal bonding treatment, or may be bonding by electron beam irradiation or ultrasonic welding. According to the heat treatment, the adhesive fibers (e.g., the low melting point component of the composite fiber) melt or soften by heating during the heat treatment, and the fibers constituting the laminated fiber webs can be bonded together.

[0106] The heat treatment may be, for example, a hot air processing treatment in which hot air is blown, a heat roll processing (heat embossing roll processing), or a heat treatment using infrared rays. The hot air processing treatment may be carried out using a device that blows hot air at a predetermined temperature onto the laminated fiber web, for example, a hot air penetration type heat treatment machine or a hot air blowing type heat treatment machine.

[0107] The heat treatment temperature (for example, the temperature of hot air) may be a temperature at which a component constituting the adhesive fiber and functioning as an adhesive component softens or melts. For example, the heat treatment temperature may be a temperature equal to or higher than the melting point of the component. For example, when the adhesive fiber contains polyethylene as a component and polyethylene is used as an adhesive component, the heat treatment temperature may be 130°C to 150°C, and when polybutylene succinate is used as an adhesive component, the heat treatment temperature may be 120°C to 133°C.

[0108] (Wiper) The nonwoven fabric of this embodiment is suitable for use as a wiper. The nonwoven fabric of this embodiment may be used as a wiper as is. Alternatively, another sheet-like material (nonwoven fabric, film, or sheet) may be attached to one surface of the nonwoven fabric of this embodiment and used as a wiper. The wiper may be held by hand and used like a dust cloth, or may be attached to a jig having a wiper attachment part at the end of a rod-shaped object.

[0109] The nonwoven fabric of this embodiment is particularly suitable for use as an objective wiper. The object wiper may be used for wiping floors, kitchens, toilets, bathtubs, furniture, vehicles, walls, screen doors, window panes, etc. The nonwoven fabric of this embodiment is suitable for wiping and collecting solid dirt (food scraps, hair) of slightly larger size, and is therefore particularly suitable for wiping and cleaning places where such dirt is likely to adhere, such as floors in dining rooms, living rooms, and washrooms, floors in restaurants and other stores, and floors in factories and workshops. The object wiper may be impregnated with water or an aqueous solution containing a cleaning component in an amount of 100 parts by mass or more and 1000 parts by mass or less per 100 parts by mass of the nonwoven fabric. The amount of impregnation may be 150 parts by mass or more, 700 parts by mass or less, or 500 parts by mass or less per 100 parts by mass of the nonwoven fabric. Alternatively, the nonwoven fabric of this embodiment may be used as a dry-type object wiper that is not impregnated with liquid.

[0110] The wiper of this embodiment is used so that the wiping surface is the surface of the fiber layer a. The fiber layer a contains a predetermined ratio of hydrophilic cellulose fibers, and when used as a wet object wiper, the impregnated liquid can be smoothly supplied to the object by applying the surface of the fiber layer a to the object. When the nonwoven fabric is manufactured by a water flow entanglement process, streaky water flow jet marks suitable for scraping off dirt are easily formed on the surface of the fiber layer a, which is also the reason why the surface of the fiber layer a is used as the wiping surface.

[0111] Since the wiper of this embodiment contains a nonwoven fabric having a stress index at MD 5% elongation within the above range, even when the wiper is applied to an object and used repeatedly to wipe the object, twisting and stretching are unlikely to occur, and deformation or expansion of inter-fiber voids caused by twisting and stretching is likely to be suppressed. Therefore, in the wiper of this embodiment, dirt once trapped in the inter-fiber voids of the wiper is unlikely to fall off, and excellent dirt collection properties are exhibited. EXAMPLES

[0112] The following fibers were prepared for use in this example. Hydrophilic cellulose fiber A (in the table, "Rayon 1.7T"): Viscose rayon with a fineness of 1.7 dtex and a fiber length of 40 mm (product name: Corona, manufactured by Daiwabo Rayon Co., Ltd.). Hydrophilic cellulose fiber B (in the table, "Rayon 3.3T"): Viscose rayon with a fineness of 3.3 dtex and a fiber length of 51 mm (product name: Corona, manufactured by Daiwabo Rayon Co., Ltd.). · Synthetic fiber a (in the table, "Bio-PP / PE1.7T"): A core-sheath type composite fiber with a fineness of 1.7 dtex and fiber length of 51 mm, the core component of which is bio-polypropylene resin and the sheath component of which is bio-polyethylene resin. · Synthetic fiber b (in the table, "PP1.0T"): A single synthetic fiber (product name: Polypro, manufactured by Yamatobo Co., Ltd.) made of polypropylene with a fineness of 1.0 dtex and a fiber length of 38 mm, with a water-repellent fiber treatment applied to the surface.

[0113] In addition, the following nonwoven fabric (intermediate fiber web) constituting the intermediate fiber layer in this example was prepared. Wet-laid nonwoven fabric 1 (in the table, "pulp"): A nonwoven fabric made of 100% wood-derived pulp fiber (fineness: approx. 1.0 to 4.0 dtex, fiber length: approx. 0.8 mm to 4.5 mm) with a basis weight of 17 g / m 2 Wet nonwoven fabric (manufactured by Habix Co., Ltd.)

[0114] Example 1 80% by mass of hydrophilic cellulose fiber A and 20% by mass of synthetic fiber A were mixed and carded using a parallel carding machine to a target weight of approximately 24 g / m 2 Thus, a first fibrous web and a second fibrous web were produced. A wet nonwoven fabric 1 was laminated on the second fiber web as an intermediate fiber layer, and the second fiber web was laminated on the wet nonwoven fabric 1 to form a laminated fiber web. The laminated fiber web was placed on a 90 mesh plain weave support, and water was sprayed on both sides of the laminated web using a nozzle with orifices having a hole diameter of 0.12 mm spaced at 0.6 mm intervals, so that the total energy TE of the water sprayed on the laminated web was 0.56 khw / kg / m. During the treatment, the distance between the nozzle and the fiber web was 15 mm.

[0115] Next, the fiber web after the hydroentanglement treatment was subjected to a heat treatment for 5 seconds using a hot air penetration type heat treatment machine set at 135°C to bond the fibers together via the sheath component of synthetic fiber a, and was then subjected to a cooling process by natural cooling in an atmosphere at room temperature of 20°C to obtain the nonwoven fabric of Example 1.

[0116] (Examples 2 to 4, Comparative Examples 1 to 4) The nonwoven fabrics of Examples 2 to 4 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1, except that the types, ratios, and targeted weights of the fibers constituting the first and second fiber webs, as well as the total energy of the water flow during the hydroentanglement treatment, were as shown in Tables 1 and 2, respectively. However, in Example 2 and Comparative Example 2, the thermal bonding treatment was not carried out, and instead, a drying treatment was carried out using a hot air penetration type heat treatment machine set at 100°C. In Comparative Example 1, a single-layer web was prepared using hydrophilic cellulose fiber 1 and synthetic fiber a, and a single-layer nonwoven fabric was formed without laminating it with an intermediate fiber web.

[0117] The nonwoven fabric was evaluated as follows. <Nonwoven fabric thickness, thickness reduction rate, bulk density> The thickness of the nonwoven fabric was measured with a thickness gauge (THICKNESS GAUGE Model CR-60A (product name) manufactured by Daiei Scientific Instruments Co., Ltd.) under a load of 0.3 kPa or 1.96 kPa. The thickness reduction rate was calculated by subtracting the thickness reduction rate from the thickness reduction rate when a load of 0.3 kPa was applied to the thickness reduction rate when a load of 1.96 kPa was applied. The bulk density was calculated from the thickness and basis weight when a load of 0.3 kPa was applied.

[0118] <Strength and elongation> The strength and elongation were measured by subjecting dry samples to a tensile test using a constant-speed tension tester in accordance with JIS L 1913:2010 6.3 under the conditions of a sample width of 5 cm, grip distance of 10 cm, and a tensile speed of 30±2 cm / min, and the load value at break (tensile strength), elongation percentage, and stress at 5% elongation (force required to elongate by 5%) were measured. The tensile test was performed in the machine direction (MD) and cross direction (CD) of the nonwoven fabric as the tensile direction. The evaluation results are shown as the average of the values ​​measured for three samples. The wet measurement was carried out by impregnating 100% by mass of the sample with 250% by mass of distilled water.

[0119] <Dirt collection ability> [Dust collection ability] 0.20 g of test powder (seven types) conforming to JIS Z 8901 was uniformly dispersed in a rectangular area of ​​5 cm length × 15 cm width (hereinafter referred to as the "dust dispersion area") approximately in the center of the surface of a white acrylic plate, and the test powder (dust) was wiped off using a nonwoven fabric (29 cm length, 21 cm width) of the Examples and Comparative Examples as a wiper.

[0120] The wiping was performed with the wiper attached to a wiper tool (product name: Quickle Wiper [tool body] head, manufactured by Kao Corporation) so that the area contributing to wiping was 26 cm vertically and 16 cm horizontally, and the surface onto which the water was last sprayed during water stream entanglement of the nonwoven fabric would be the wiped surface, with a load of 400 gf being applied. The wiper was moved back and forth once on the surface of the white acrylic plate to wipe.

[0121] More specifically, Place the wiper in the center of the dust distribution area so that the vertical direction of the wiper coincides with the vertical direction of the dust distribution area; From there, move the wiper 250 mm toward the left end of the dust dispersion area to rub the dust (white acrylic plate). Then, move the wiper 500 mm toward the right end of the dust dispersion area, -Move the wiper 250 mm further toward the left end of the dust dispersion area. The wipers went back and forth once.

[0122] After the wiper was moved back and forth once, the dust collection rate was calculated from the mass of the nonwoven fabric measured beforehand and the mass of the nonwoven fabric measured after wiping. For each nonwoven fabric, wiping was measured three times with the wiping surface of the nonwoven fabric renewed, and the average value was taken as the dust collection rate.

[0123] [Hair collection ability (wet)] A total of five hairs (approximately 5 cm long) were placed on the flooring with some space between them: three strands horizontally and two strands vertically, and the hairs were wiped off with the nonwoven fabrics of the Examples and Comparative Examples.

[0124] Wiping was performed in a wet state by impregnating 250 parts by mass of distilled water with respect to 100 parts by mass of nonwoven fabric. Wiping was performed by attaching the nonwoven fabric to a wiper tool (product name: head part of Quickle Wiper [tool body], manufactured by Kao Corporation) so that the area contributing to wiping was 26 cm in the vertical direction and 16 cm in the horizontal direction, and applying a load of 400 gf. Wiping was performed by moving the wiper back and forth once on the hair in the same manner as that used in the evaluation of dust collection ability described above. After wiping, the collection rate (%) was calculated from the number of hairs wiped off from the flooring. For each nonwoven fabric, wiping was measured three times with the wiping surface of the nonwoven fabric renewed, and the average value was taken as the hair collection rate.

[0125] [Sesame capture ability (wet condition)] For the sesame seed collection, 10 sesame seeds were placed on the flooring in three rows (3-4-3 rows) at intervals, and the nonwoven fabric was used to wipe them off in the same manner as for the evaluation of hair collection (wet state). After wiping, the collection rate (%) was calculated from the number of sesame seeds wiped off from the flooring. For each nonwoven fabric, wiping was performed three times with the wiping surface of the nonwoven fabric fresh, and the average value was taken as the sesame seed collection rate.

[0126] <Initial release rate of liquid> In the evaluation of hair collection ability, the mass of the nonwoven fabric impregnated with distilled water was measured before and after the first wiping, and the reduction in mass was regarded as the liquid released by one round trip of the wet nonwoven fabric. The ratio of the released liquid to the amount of distilled water impregnated with 250 parts by mass per 100 parts by mass of nonwoven fabric was calculated in %.

[0127] The evaluation results of each of the examples and comparative examples are shown in Tables 1 and 2.

[0128] [Table 1]

[0129] [Table 2]

[0130] All of the nonwoven fabrics of Examples 1 to 4 exhibited generally excellent dirt collection properties (hair collection rate ≧30%, sesame seed collection rate >60%, and dust collection rate ≧34%).

[0131] Comparative Example 1 had a low stress index at MD5% elongation because it did not have an intermediate fiber layer. Comparative Example 2 had a low stress index at MD5% elongation because the first and second fiber layers contained polypropylene fibers and the fibers were not bonded to each other, and the polypropylene fibers were water repellent and not easily entangled by water flow entanglement. All of these comparative examples showed lower dirt collection performance than the examples, and in particular, the dust collection rate and sesame collection rate were low. In addition, Comparative Examples 1 and 2 showed a higher initial release rate than the examples, and were more likely to release liquid at the initial stage of wiping work. This is thought to be because Comparative Example 1 did not have an intermediate fiber layer that served as a tank for storing liquid, and Comparative Example 2 had a low degree of entanglement between the fibers, resulting in the formation of large inter-fiber voids.

[0132] Comparative Example 3, like Comparative Example 2, contained polypropylene fibers, but these did not function as adhesive fibers, and the polypropylene fibers were water-repellent and difficult to be entangled by hydroentanglement, so the stress index at MD5% elongation was low, and the dirt collection ability was also inferior to that of the Examples. Comparative Example 4 was produced using the same fibers as in Example 1 in the same ratio, but the total energy TE of the water stream sprayed on the laminated web during the hydroentanglement treatment was low at 0.10 khw / kg / m, so the stress index at MD5% elongation was low. Therefore, the dirt collection ability was inferior to that of Example 1.

[0133] Example 5 80% by mass of hydrophilic cellulose fiber A and 20% by mass of synthetic fiber A were mixed and carded using a parallel carding machine to a target weight of approximately 24 g / m 2 Thus, a first fibrous web and a second fibrous web were produced. A wet nonwoven fabric 1 was laminated on the second fiber web as an intermediate fiber layer, and the second fiber web was laminated on the wet nonwoven fabric 1 to form a laminated fiber web. The laminated fiber web was placed on a 90-mesh plain weave support, and a columnar water stream was sprayed onto one surface of the laminated web using a nozzle having orifices with a hole diameter of 0.12 mm arranged at 0.6 mm intervals, and then a columnar water stream was sprayed onto the other surface. Furthermore, a pattern-forming nozzle was prepared in which some of the orifices in the nozzle having orifices with a hole diameter of 0.12 mm arranged at 0.6 mm intervals were blocked to prevent the water stream from being sprayed from the orifices, and a columnar water stream was sprayed onto the other surface from the nozzle. The hydroentanglement treatment was carried out so that the total energy TE of the sprayed water stream was 0.72 hw / kg / m.

[0134] The pattern forming nozzle had orifice-blocked portions P1 and orifice-unblocked portions P2, each 10 mm long in the CD direction, arranged alternately in the CD direction. The web after hydroentanglement had a striped pattern due to the difference in the degree of entanglement between the portions hit by the water stream from the stripe pattern forming nozzle (highly entangled portions) and the portions not hit by the water stream (lowly entangled portions).

[0135] Next, the fiber web after the hydroentanglement treatment was subjected to a heat treatment for 5 seconds using a hot air penetration type heat treatment machine set at 135°C to bond the fibers together via the sheath component of synthetic fiber a, and was then subjected to a cooling process by natural cooling in an atmosphere at room temperature of 20°C to obtain the nonwoven fabric of Example 5.

[0136] Example 6 The nonwoven fabric of Example 6 was obtained according to the same procedure as that employed in Example 5, except that the hydroentanglement treatment was carried out under the following conditions.

[0137] [Water flow entanglement treatment] The laminated fiber web was placed on a 90 mesh plain weave support, and a nozzle with orifices of 0.12 mm diameter spaced 0.6 mm apart was used to spray a columnar water stream onto one surface of the laminated web, and then spray a columnar water stream onto the other surface. Furthermore, the same nozzle as the pattern forming nozzle used in Example 5 was prepared, and a columnar water stream was sprayed onto the other surface from the nozzle while the laminated web was placed on a woven support with a warp diameter of 0.7 mm, a weft diameter of 0.9 mm, a warp density of 41 / inch, a weft density of 16 / inch, and a 3 / 1 herringbone weave. The hydroentanglement treatment was carried out so that the total energy TE of the sprayed water stream was 0.72 khw / kg / m.

[0138] The web after the hydroentanglement had a striped pattern in which parts having a herringbone pattern and parts not having a herringbone pattern were arranged alternately in the CD direction. This pattern was formed because the degree of entanglement differed between the parts hit by the water jet from the stripe pattern forming nozzle and the parts not hit by the water jet, and because the parts hit by the water jet were placed on a herringbone support. Example 7 The nonwoven fabric of Example 6 was obtained according to the same procedure as that employed in Example 5, except that the hydroentanglement treatment was carried out under the following conditions. [Water flow entanglement treatment] The laminated fiber web was placed on a 90 mesh plain weave support, and a columnar water stream was sprayed onto one surface of the laminated web, followed by another columnar water stream onto the other surface, using a nozzle with orifices of 0.12 mm diameter spaced 0.6 mm apart, so that the total energy TE of the water stream sprayed onto the laminated web was 0.90 khw / kg / m. During the treatment, the distance between the nozzle and the fiber web was 15 mm. The evaluation results of Examples 5 to 7 are shown in Table 3.

[0139] [Table 3]

[0140] The nonwoven fabric of Example 7 has the same fiber structure and basis weight as Example 1, but is manufactured by increasing the total energy TE of the jetted water stream compared to Example 1. Due to the increase in TE, some of the fibers (pulp) of the intermediate fiber layer were observed to fall off during the manufacture of Example 7, and as a result, the stress index at MD5% elongation in the dry and wet states was lower than that of Example 1, which is thought to have led to a decrease in dirt collection performance. Furthermore, while the degree of entanglement between the fibers in Example 7 is higher than that of Example 1, the movement of the fibers is restricted compared to Example 1, and the inter-fiber voids are less likely to deform, which is also presumably the reason why the dirt collection performance is lower than that of Example 1.

[0141] The nonwoven fabrics of Examples 5 and 6 were produced by increasing the total energy TE of the jetted water stream to a value higher than that of Example 1, but one jet of water stream was performed using a pattern-forming nozzle. Examples 5 and 6 showed higher dirt collection performance than Example 7, and also showed better collection performance than Example 1 for some types of dirt when compared with Example 1. This is thought to be because the water stream from the pattern-forming nozzle hits only a part of the laminated web, so that the intermediate fiber layer is less likely to fall off as seen in Example 7, and the stress index at MD5% elongation in both dry and wet states is higher than that of Example 1. Furthermore, in these Examples, the degree of freedom of the fibers is low in the low intertwining part, and there are irregularities due to the pattern formation, which are also thought to contribute to the improvement of dirt collection performance. In particular, Example 6 uses a herringbone support when jetting the water stream from the stripe pattern-forming nozzle, so that irregularities are formed even in the part where the water stream is jetted, which is thought to have improved dirt collection performance.

[0142] This embodiment includes the following aspects. (Aspect 1) a first fiber layer, a second fiber layer, and an intermediate fiber layer located between the first fiber layer and the second fiber layer; one of the first fiber layer and the second fiber layer is a fiber layer a containing 50% by mass or more of hydrophilic cellulose fibers, the intermediate fiber layer is a fiber layer containing 50% by mass or more of hydrophilic cellulose fiber and / or a wetlaid nonwoven fabric composed of short fibers having a fiber length of 20 mm or less; Each fiber layer is integrated by intertwining the fibers. The stress (N / 5cm) at 5% elongation in the MD direction in a dry state is expressed as the basis weight (g / m 2 ) is 0.150 or more, and / or the stress (N / 5cm) at 5% elongation in the MD direction in a wet state in which 100 parts by mass of nonwoven fabric are soaked in 250 parts by mass of water is divided by the weight (g / m 2 ) The stress index at MD5% elongation divided by is 0.050 or more. Nonwoven fabric for objective wipers. (Aspect 2) The nonwoven fabric for an object wiper according to embodiment 1, wherein the first fibrous layer and the second fibrous layer are both the fibrous layer a. (Aspect 3) 3. The nonwoven fabric for an object wiper according to embodiment 1 or 2, wherein the intermediate fiber layer is a wet-laid nonwoven fabric made of pulp. (Aspect 4) The nonwoven fabric for an objective wiper according to any one of aspects 1 to 3, wherein the fiber layer a contains more than 0 mass % and not more than 50 mass % of synthetic fibers. (Aspect 5) The nonwoven fabric for an objective wiper according to embodiment 4, wherein the synthetic fibers are one or more types of synthetic fibers selected from synthetic fibers containing biomass raw materials, biodegradable synthetic fibers, and synthetic fibers containing recycled raw materials. (Aspect 6) 6. The nonwoven fabric for an objective wiper according to embodiment 4 or 5, wherein a part or all of the synthetic fibers are adhesive fibers, and the fibers in the fiber layer a are bonded to each other by the adhesive fibers. (Aspect 7) The nonwoven fabric for an object wiper according to any one of embodiments 1 to 6, having an elongation (%) in a dry state and / or an elongation (%) in a wet state in which 100 parts by mass of the nonwoven fabric are impregnated with 250 parts by mass of water, of 85% or more. (Aspect 8) The fiber optics includes a highly entangled portion having a higher degree of entanglement between fibers and a low entangled portion having a lower degree of entanglement between fibers, the highly entangled portions and the less entangled portions are alternately arranged in a plan view, The width of the less entangled portion is 2 mm or more and 50 mm or less. The nonwoven fabric for an object wiper according to any one of embodiments 1 to 7. (Aspect 9) 9. The nonwoven fabric for an object wiper according to embodiment 8, wherein a low-density region is formed in the highly entangled portion. (Aspect 10) Preparing a laminated web having an intermediate fibrous web disposed between a first fibrous web and a second fibrous web; subjecting the laminated web to a high pressure fluid stream entanglement treatment; Including, one or both of the first fiber web and the second fiber web is a fiber web A containing 50% by mass or more of hydrophilic cellulose fibers, The intermediate fiber web is a fiber web and / or a wet-laid nonwoven fabric containing 50% by mass or more of hydrophilic cellulose fibers, The entanglement treatment is carried out so that the total energy TE of the water stream sprayed onto the laminated web is 0.11 khw / kg / m or more and 1.20 khw / kg / m or less. The stress (N / 5cm) at 5% elongation in the MD direction in a dry state is expressed as the basis weight (g / m 2 ) is 0.150 or more, and / or the stress at 5% elongation in the MD direction (N / 5cm) in a wet state in which 100 parts by mass of nonwoven fabric are impregnated with 250 parts by mass of water is divided by the basis weight (g / m 2 ) is 0.050 or more. (Aspect 11) The manufacturing method of embodiment 10, wherein the entanglement treatment comprises spraying a water flow from a nozzle having an orifice assembly portion on a side surface of the fibrous web A, the nozzle having an orifice-free portion having a width of 2 mm or more and 50 mm or less and disposed between the orifice assembly portions, to alternately form highly entangled portions and less entangled portions in the CD direction. (Aspect 12) The nonwoven fabric for object wipers according to any one of the first to ninth aspects is impregnated with a liquid in an amount of 100 parts by mass or more and 1,000 parts by mass or less, The surface of the fiber layer a is used as a wiping surface. Objective wiper. [Industrial Applicability]

[0143] The nonwoven fabric of the present disclosure has a high stress index at MD 5% elongation, and is less likely to twist or stretch when rubbed against an object, and deformation and expansion of interfiber voids are suppressed. Therefore, the nonwoven fabric of the present disclosure can be suitably used as a wiper with excellent dirt collection properties, particularly as an object wiper for wiping off dirt of a slightly large size.

Claims

1. a first fiber layer, a second fiber layer, and an intermediate fiber layer located between the first fiber layer and the second fiber layer; one of the first fiber layer and the second fiber layer is a fiber layer a containing 50% by mass or more of hydrophilic cellulose fibers, the intermediate fiber layer is a fiber layer containing 50% by mass or more of hydrophilic cellulose fiber and / or a wetlaid nonwoven fabric composed of short fibers having a fiber length of 20 mm or less, Each fiber layer is integrated by intertwining the fibers. The stress at 5% elongation in the MD direction in a dry state (N / 5cm) is calculated based on the basis weight of the nonwoven fabric (g / m ２ ) is 0.150 or more, and / or the stress (N / 5cm) at 5% elongation in the MD direction in a wet state in which 100 parts by mass of the nonwoven fabric are impregnated with 250 parts by mass of water is divided by the basis weight (g / m ２ ) is 0.050 or more, Nonwoven fabric for objective wipers.

2. The nonwoven fabric for an object wiper according to claim 1 , wherein both of the first fiber layer and the second fiber layer are the fiber layer a.

3. 3. The nonwoven fabric for an object wiper according to claim 1, wherein the intermediate fiber layer is a wet-laid nonwoven fabric made of pulp.

4. The nonwoven fabric for an object wiper according to claim 1 or 2, wherein the fiber layer a contains more than 0 mass % and 50 mass % or less of synthetic fibers.

5. The nonwoven fabric for an object wiper according to claim 4, wherein the synthetic fibers are one or more types of synthetic fibers selected from the group consisting of synthetic fibers containing biomass raw materials, biodegradable synthetic fibers, and synthetic fibers containing recycled raw materials.

6. 5. The nonwoven fabric for an object wiper according to claim 4, wherein a part or all of the synthetic fibers are adhesive fibers, and the fibers in the fiber layer a are bonded to each other by the adhesive fibers.

7. 3. The nonwoven fabric for object wipers according to claim 1, wherein the nonwoven fabric has an elongation (%) in a dry state and / or an elongation (%) in a wet state in which 100 parts by mass of the nonwoven fabric are impregnated with 250 parts by mass of water, of 85% or more.

8. The fiber optics includes a highly entangled portion having a higher degree of entanglement between fibers and a low entangled portion having a lower degree of entanglement between fibers, the highly entangled portions and the less entangled portions are alternately arranged in a plan view, The width of the less entangled portion is 2 mm or more and 50 mm or less. The nonwoven fabric for an object wiper according to claim 1.

9. The nonwoven fabric for an object wiper according to claim 8 , wherein a low density region is formed in the highly entangled portion.

10. Preparing a laminated web having an intermediate fibrous web disposed between a first fibrous web and a second fibrous web; subjecting the laminated web to a high pressure fluid stream entanglement treatment; Including, one or both of the first fiber web and the second fiber web is a fiber web A containing 50% by mass or more of hydrophilic cellulose fibers, The intermediate fiber web is a fiber web containing 50% by mass or more of hydrophilic cellulose fibers and / or a wet-laid nonwoven fabric, The entanglement treatment is carried out so that the total energy TE of the water stream sprayed on the laminated web is 0.11 khw / kg / m or more and 1.20 khw / kg / m or less. The stress at 5% elongation in the MD direction in a dry state (N / 5cm) is calculated based on the basis weight of the nonwoven fabric (g / m ２ ) is 0.150 or more, and / or the stress (N / 5cm) at 5% elongation in the MD direction in a wet state in which 100 parts by mass of the nonwoven fabric are impregnated with 250 parts by mass of water is divided by the basis weight (g / m ２ (a) a stress index at 5% elongation in MD divided by (b) is 0.050 or more.

11. The manufacturing method according to claim 10, wherein the entanglement treatment includes spraying a water flow from a nozzle having an orifice assembly section in which orifices are provided at regular intervals on the side surface of the fibrous web A and an orifice-free section having a width of 2 mm or more and 50 mm or less provided between the orifice assembly sections, to form highly entangled sections and less entangled sections alternately in the CD direction.

12. The nonwoven fabric for an object wiper according to claim 1, 2 or 8 is impregnated with a liquid in an amount of 100 parts by mass or more and 1000 parts by mass or less, The surface of the fiber layer a is used as a wiping surface. Objective wiper.

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