JP2025015521A - Nonwoven fabric for objective wiper and objective wiper - Google Patents

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

This disclosure relates to a nonwoven fabric for an object wiper and a wiper including the nonwoven fabric.

One of the uses of nonwoven fabrics is a wiper (object wiper) for wiping off dirt from objects. For example, Patent Document 1 proposes that a nonwoven fabric wiper containing fibers with curved portions, at least a part of which has multiple bends, and the number of curved portions with multiple bends is two or more per 1 ^mm2 of the surface of the nonwoven fabric wiper, is used as an industrial wiper suitable for wiping uneven surfaces (for example, fine mesh used for screen printing). Patent Document 2 also proposes that a fiber sheet formed of biodegradable fibers containing at least water-absorbent fibers is used for wiping work in a wet state, the fiber sheet containing a cleaning composition consisting of a compound recognized as a food and/or food additive.

JP 2016-068032 A JP 2000-102492 A

Provides a nonwoven fabric that provides an objective wiper with high dirt collection properties, etc.

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 fiber and/or a wet-laid nonwoven fabric,
the stress index at 5% elongation in the MD direction in a dry state (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.150 or more, and/or the stress index at 5% elongation in the MD direction in a wet state in which the nonwoven fabric is impregnated with ²⁵⁰ parts by mass of water per 100 parts by mass of the nonwoven fabric (N/5cm) is 0.050 or more;
This is a nonwoven fabric for objective wipers.

When the nonwoven fabric of the present disclosure is used as an object wiper, dirt that has been absorbed into the nonwoven fabric is less likely to fall off, improving the wiper's ability to collect dirt.

(Background to the development of the nonwoven fabric for wipers according to the present disclosure)
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 therefore emphasis is placed on the ability to capture slightly larger solid particles (the ability to retain wiped dirt within the wiper).

After studying configurations for improving the capture of various types of dirt, including solid dirt of somewhat large dimensions, the inventors concluded that when using a single wiper to wipe an object (e.g., a floor of several tatami mats) by rubbing it, the wiper is likely to be loaded by static friction in the early stages of the wiping action, causing twisting and stretching, and thus preventing the initial capture ability from being fully demonstrated. On the other hand, they also thought that when a certain amount of dirt has been captured in the middle to late stages of the wiping action, the voids within the wiper decrease and the wiper becomes saturated with dirt, preventing it from capturing much dirt. Furthermore, they thought that the twisting and stretching of the wiper that occurs during the wiping operation causes the voids between the fibers to deform or expand, causing the held dirt to fall off.

The inventors therefore investigated the relationship between the twisting and stretching that occurs during wiping work and the dirt capture properties and the shedding of dirt during wiping work, and concluded that twisting and stretching are related to the stress at 5% elongation in the MD direction (also called the machine direction) of the nonwoven fabric that constitutes the wiper. They then discovered that a nonwoven fabric that is configured so that the stress index at 5% elongation in the MD direction, calculated 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 dirt capture properties. In addition, when such a nonwoven fabric is manufactured by an entanglement processing method using a high-pressure fluid flow, the fluid marks formed as streaky irregularities by the injection of the fluid flow tend to become clearer, and it was inferred that the irregularities play a role in scraping off dirt and also hold the dirt, thereby further improving dirt capture properties.

The total energy of the water stream 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 tending to be 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 a concave 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.

(Configuration 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 composed of short fibers having a fiber length of 20 mm or less,
Each fiber layer is integrated by intertwining the fibers.
The nonwoven fabric for object wipers has a stress index at 5% elongation in the MD direction of 0.150 or more, calculated by dividing the stress (N/5cm) at 5% elongation in the MD direction in a dry state by the basis weight (g/ ^{m2 )} of the nonwoven fabric, and/or a stress index at 5% elongation in the MD direction of 0.050 or more, calculated by dividing the stress (N/5cm) at 5% elongation in the MD direction in a wet state in which the nonwoven fabric is impregnated with 250 parts by mass of water per 100 parts by mass of the nonwoven fabric.

In the nonwoven fabric for object wipers of this embodiment (hereinafter also 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 and facilitate the manufacture of a nonwoven fabric with high stress at MD 5% elongation. 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 with high stress at MD 5% elongation. 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 fibers with short fiber length, entanglement of the fibers tends to progress more. Therefore, even in a configuration in which the fiber layer a contains hydrophilic cellulose fibers and the intermediate fiber layer is a wet-laid nonwoven fabric, it is easy to obtain a nonwoven fabric with high stress at 5% elongation in the MD.

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 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 object wiper, when wiping off liquid, the hydrophilic cellulose fibers contained in fiber layer a and the intermediate fiber layer absorb the wiped liquid, making it less likely that the liquid will remain on the object.

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, are 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 proportion of hydrophilic cellulose fibers is small, the amount of liquid impregnated into the nonwoven fabric will be 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 proportion 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 5% elongation in the MD may not be in the above range.

In addition to hydrophilic cellulose fibers, the fiber layer a may contain other fibers, and in particular may contain synthetic fibers as the other fibers. Synthetic fibers are preferably used in terms of improving the mechanical strength of the nonwoven fabric and imparting rigidity to the nonwoven fabric. Details of 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 entangling them with a high-pressure water flow, and the stress index at MD 5% elongation in the above range may not be obtained. Furthermore, if the proportion of synthetic fibers is too high, the interfiber voids in the nonwoven fabric may become excessively large. Since liquid held in the large interfiber 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 liquid that has been wiped off may be released back onto the target object.

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, a 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 a fiber 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.

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 adhesive fibers makes it easier to obtain a stress index at 5% elongation in the MD in the above range. Therefore, adhesive fibers are preferably used in this embodiment. However, even if adhesive fibers are not included, it is possible to achieve a stress index at 5% elongation in the MD in the above range by appropriately selecting the configuration of the fiber layer a and the intermediate fiber layer and appropriately selecting the manufacturing conditions of the nonwoven fabric.

When synthetic fibers are contained in the fiber layer a, the synthetic fibers may be 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. From the perspective of the SDGs, such synthetic fibers are preferably used together with hydrophilic cellulose fibers.

The fiber layer a may also contain other fibers such as water-repellent cellulose fibers and natural fibers that are not hydrophilic cellulose fibers. Here, water-repellent cellulose fibers refer to cellulose fibers that are inherently hydrophilic but have been artificially given water repellency, as described below.

In this embodiment, either 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.

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, and the manufacturing form of the fiber layer (type of fiber web). 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 can be used to wipe flooring surfaces and the other surface can be used to wipe bathroom floors).

In this embodiment, the intermediate fiber layer is a fiber layer containing 50% or more by mass of hydrophilic cellulose fibers and/or a wet-laid nonwoven fabric made 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.

When the intermediate fibrous layer is a fibrous layer containing hydrophilic cellulose fibers, the proportion of the 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 the entanglement of the fibers between the first fiber layer and the second fiber layer and the intermediate fiber layer when the fibers are entangled with each other using a 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 5% elongation in MD may not be within the above range.

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

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

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 (e.g., cleaning liquid contained in the wet wipe) and can supply liquid to the wiping surface for a long period of time during the wiping operation, or can hold the liquid that has been wiped off.

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, so when the fibers are entangled with each other by a high-pressure water flow, they 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 5% elongation in the MD 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.

In the nonwoven fabric of this embodiment, the fiber layer a may have a basis weight of, for example, 10 g/m ² or more and 70 g/m ² or less, particularly 10 g/m ² or more and 65 g/m ² or less, more particularly 15 g/m ² or more and 60 g/m ² or less, and even more particularly 20 g/m ² or more and 55 g/m ² or less. When either the first fiber layer or the second fiber layer is not the fiber layer a, the basis weight of the fiber layer other than the fiber layer a may have a basis weight of, for example, 10 g/m ² or more and 65 g/m ² or less, particularly 15 g/m ² or more and 60 g/m ² or less, and more particularly 20 g/m ² or more and 55 g/m ² or less.

When the fiber layer a exists as a first fiber layer and a second fiber layer, the first fiber layer and the second fiber layer may each have a basis weight of, for example, 10 g/m2 or ^more and 50 g/m2 or ^less , particularly 12.5 g/m2 ^or more and 47.5 g/m2 or ^less , more particularly 15 g/m2 ^{or more} and 45 g/m2 or ^less , and even more particularly 17.5 g/ ^m2 or more and 40 g/m2 or ^less .

The intermediate fiber layer which constitutes the nonwoven fabric together with the first and second fiber layers may have a basis weight of, for example, 5 g/ ^m2 or more and 50 g/m2 ^or less, particularly 6 g/m2 or ^more and 45 g/m2 ^or less, more particularly 7 g/m2 ^{or more} and 40 g/m2 ^or less, and even more particularly 8 g/m2 ^or more and 35 g/m2 or ^less .

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 proportion of the intermediate fiber layer in 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 proportion of the basis weight of the intermediate fiber layer is too small, the stress index of the nonwoven fabric at 5% elongation in the MD may be outside the above range.

The weight of the entire nonwoven fabric of this embodiment may be appropriately selected depending on the application, etc. The nonwoven fabric of this embodiment may have a weight of, for example, 30 g/m ² or more and 100 g/m ² or less, particularly 35 g/m ² or more and 95 g/m ² or less, more particularly 40 g/m ² or more and 90 g/m ² or less, and even more particularly 45 g/m ² or more and 85 g/m ² or less.

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

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 entire nonwoven fabric. 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.

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

Each low-density region may have an area of, for example, 0.03 mm ² to 20 mm ² , particularly 0.1 mm ² to 10 mm ² , and more particularly 0.7 mm ² to 5.0 mm ^2. 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, it may not be sufficiently recognized, and the design effect may not be fully exerted. If the low-density region is too large, the nonwoven fabric is prone to deformation or damage such as stretching, twisting, and tearing, and the handleability is reduced. In addition, if the low-density region is too large, it may be difficult to recognize it as a low-density region, and the design effect may not be fully exerted.

The low density regions may be open areas where no fibers are present, or may not be open areas. Alternatively, in a single nonwoven fabric, open areas and low density regions that are not open areas may both exist to form a pattern.

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 in 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).

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

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

The nonwoven fabric of this embodiment has a stress index of 0.150 or more when elongated by 5% in the MD when dry, and/or a stress index of 0.050 or more when elongated by 5% in the MD when wet, so that when it is impregnated with liquid and used as a wiper, twisting and stretching during wiping are suppressed, and the inter-fiber voids are enlarged due to twisting and stretching, preventing the collected dirt from falling off.

In addition, when a nonwoven fabric having a stress index at 5% elongation in the MD when dry and/or a stress index at 5% elongation in the MD when wet that is 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). These irregularities are believed to contribute to the scraping or entangling of dirt, and, together with the high stress index at 5% elongation in the MD of the nonwoven fabric, improve the dirt collection ability of the nonwoven fabric.

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 is 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. Or, 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 fiber movement.

The nonwoven fabric of this embodiment may have a tensile strength in the MD direction when dry of, for example, 30 N/5 cm or more and 200 N/5 cm or less, particularly 35 N/5 cm or more and 195 N/5 cm or less, and more particularly 40 N/5 cm or more and 190 N/5 cm 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.

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.

The nonwoven fabric of this embodiment may have an elongation rate in the CD direction 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 elongation rate in the CD direction 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 elongation rate in the CD direction when dry is too high, the sheet will tend 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.

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, and 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 become rigid. If a rigid nonwoven fabric is used as a wiper, the target object may be scratched.

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.

The nonwoven fabric of this embodiment may have a CD elongation rate 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 rate 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 rate when wet is too high, the sheet will tend to elongate significantly due to the influence of external pressure on the sheet when used as a wiper, and dirt that has been captured may fall off.

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

The stress index at 5% elongation in CD when dry may be 0.010 or more, more particularly 0.012 or more. The stress index at 5% elongation in 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 in CD when wet may be 0.0035 or more, more particularly 0.0040 or more. The stress index at 5% elongation in CD when wet may be 0.040 or less, more particularly 0.035 or less, more particularly 0.030 or less.

When the stress index at CD 5% elongation in the dry and/or wet state is within the above range, the fibers and 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, the nonwoven fabric is less likely to deform when removed from the packaging of the wiper product or when attached to a jig for use, making it easy to handle.

Next, the fibers constituting the nonwoven fabric according to the present disclosure will be described.
(hydrophilic cellulose fibers)
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.

<Measurement of Sedimentation Velocity>
In accordance with the standard for medical gauze and medical absorbent cotton, Yakushokuki-hatsu No. 0630001, the sedimentation velocity (6(1)Ka) is measured using the following method.

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

If the fibers cannot be defibrated using 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 this using a carding machine, 0.3 g of nonwoven fabric pieces cut into 1 cm x 1 cm pieces may be dropped into water.

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) pulps such as mechanical pulps, regenerated pulps, and chemical pulps.

The hydrophilic cellulose fibers may be regenerated fibers. Regenerated fibers are preferably used because the fineness can be easily adjusted and there is little variation. Of the 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 make it possible to capture dirt in the recesses themselves.

When solvent-spun cellulose fibers such as lyocell are used as hydrophilic cellulose fibers, the strength of the fibers decreases little when wet, and the mechanical properties of the nonwoven fabric when wet can be improved.

The fineness of the hydrophilic cellulose fibers may be, for example, 0.2 dtex to 8.0 dtex, particularly 0.3 dtex to 7.0 dtex, more particularly 0.4 dtex to 6.0 dtex, and even more particularly 0.6 dtex to 5.0 dtex. 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 those 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 to 4.0 dtex and a fiber length of about 0.8 mm to 4.5 mm are mixed, and may be used in this form.

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 depending on 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.

As described above, the intermediate fiber layer may be a wet nonwoven fabric, in which 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 predetermined 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.

In this embodiment, pulp is preferably used as the hydrophilic cellulose fiber contained in the intermediate fiber layer. The pulp may be produced by a conventional method using softwood or hardwood. The pulp may also be produced by a conventional method using non-wood materials such as cotton linters, kenaf, bagasse, bamboo, straw, esparto, and seaweed. Pulp is readily accepted by consumers because of its proven use as a material for sanitary products and household goods, and is 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 fibers 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 5% elongation in the MD.

(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.

[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 the SDGs are emphasized.

Alternatively, the synthetic fiber may be a synthetic fiber containing a biomass raw material. Synthetic fibers containing biomass raw materials include, for example, 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 the SDGs are emphasized.

Alternatively, the synthetic fibers may be synthetic fibers 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 emphasis is placed on the SDGs.

In the following, when the resins specifically mentioned are provided as biomass raw materials or recycled resin raw materials, they also refer to those raw materials. For example, when we say polypropylene single fiber, it includes not only single fibers made from ordinary polypropylene raw materials, but also single fibers made from biopolypropylene and recycled (regenerated) polypropylene single fibers.

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 core-sheath composite fibers, sea-island composite fibers, side-by-side composite fibers, or split composite fibers. The cross sections of the fibers may be circular or noncircular, and noncircular shapes include elliptical, Y-shaped, X-shaped, well-shaped, multi-lobed, 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 may be a mixture of two or more types of resin.

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.

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 that 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.

Alternatively, the combination of 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.

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, or 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, as long as the "polyethylene" contains 50% by mass or more of polyethylene, it may contain other thermoplastic resins and additives, etc. This also applies to the following examples.

When the synthetic fibers are concentric or eccentric core-sheath composite fibers in which a thermoplastic resin with a higher melting point constitutes the core component as the first component and a thermoplastic resin with a lower melting point constitutes the sheath component as the 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.

In the case of core-sheath 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.

In the case of splittable composite 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 composite fibers, the number of divisions (i.e., the number of sections in the composite 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.

In this embodiment, the synthetic fibers can preferably be core-sheath type composite fibers (concentric or eccentric) in which the first component/second component combination 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.

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 may be low and the nonwoven fabric may be easily stretched, and the fiber density of the surface of the nonwoven fabric may be high, making it easy for clogging with dirt to occur and reducing the dirt collection ability. If the fineness of the synthetic fibers is too large, the touch of the nonwoven fabric may be hard. If the nonwoven fabric is easily stretched, for example, when the nonwoven fabric is attached to a jig for wiping work, sagging or wrinkles may occur when the nonwoven fabric is attached to the jig, and the fiber density of the surface of the nonwoven fabric may be low, causing dirt that has once been collected to fall off.

When synthetic fibers are the adhesive fibers, the fineness of the adhesive fibers may be from 0.8 dtex to 6.4 dtex, in particular from 1.0 dtex to 5.6 dtex, more particularly from 1.2 dtex to 4.4 dtex, and even more particularly from 1.4 dtex to 2.0 dtex.
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.

In particular, when the synthetic fiber is a splittable composite fiber, the splittable composite 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 having a fineness of 0.1 dtex or more and less than 1.0 dtex after splitting.

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, etc. For example, in the manufacture of the nonwoven fabric, when the fiber layer is manufactured by preparing a card web, the synthetic fibers may be short fibers. The fiber length of this short fiber 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 the 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 nonwoven fabric, the fiber length may be, for example, 20 mm or less.

Synthetic fibers are generally hydrophobic and have, for example, a nominal moisture regain of less than 5%. In this embodiment, the synthetic fibers may have been subjected to a hydrophilization treatment. Examples of hydrophilization treatments 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 easier to obtain a nonwoven fabric having a stress index of 0.150 or more at 5% elongation in the MD in a dry state and/or a stress index of 0.050 or more at 5% elongation in the MD in a wet state.

Although synthetic fibers have been described above as other fibers, the other fibers are not limited to these. The nonwoven fabric of this embodiment may contain, as other fibers, for example, water-repellent cellulose fibers or natural fibers such as silk and wool.

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;
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.
It is produced by the method.

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 described here.

The first and second fiber webs can be produced by known methods. The form of each fiber web may be any selected from, for example, parallel webs, cross webs, carded webs such as semi-random webs and random webs, air-laid webs, and wet-laid paper webs. 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, which makes it easier to improve the mechanical properties in the MD direction and makes it easier to set the stress at 5% MD elongation in the above range.

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 (e.g., 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 together.

The laminated fiber web, in which an 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.

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 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, on the front and back surfaces of the laminated fiber web 1 to 5 times. The water pressure is preferably 1 MPa or more and 15 MPa or less, and 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, etc., so that the stress index at MD 5% elongation in the dry state and/or the stress index at MD 5% elongation in the wet state of the obtained nonwoven fabric are within the above ranges.

In order to obtain a nonwoven fabric having a stress index at 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 process. 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 in particular 0.115 khw/kg/m or more and 1.10 khw/kg/m or less.

The energy (E) applied to the fiber web by the sprayed 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 sprayed on the side of the first fiber web and the energy E2 of the water stream sprayed on the side of the second fiber web, and then calculating their sum.

E=W×N×T/(M/1000×U×60)/1000
E: Energy applied per 1 m width per 1 kg of fiber web per hour (kWh/kg/m)
W: Power (W) of the fluid (water in this embodiment) per one orifice of the nozzle
N: number of orifices per 1 m width in the nozzle; T: number of sprays; M: basis weight (g/m ² ) of the subject of hydroentanglement treatment;
U: conveying speed (m/min)

In the above formula, W (the power of the fluid per one orifice of the nozzle) 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/ ^cm2 )
F: flow rate of water discharged from one orifice of the nozzle (cm ³ /min)

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 x V
F: 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)

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: Gravitational acceleration, 9.8 m/s ²
P1: Water pressure (kgf/ ^cm2 )
P2: Atmospheric pressure (kgf/ ^cm2 )
ρ: density of fluid (g/cm ³ )
Details of the method for determining E etc. are described in Japanese Patent No. 4,893,256.

The hydroentanglement process 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 resulting nonwoven fabric. Specifically, after hydroentanglement is performed on the entire laminated web using the nozzle exemplified above, a nonwoven fabric having a pattern can be obtained by performing hydroentanglement 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 orifices are drilled are arranged alternately.

The areas where the water flow from the orifices of the orifice assembly hits form band-shaped highly entangled areas, and the areas located below the orifice-free areas form low entangled areas. The thickness of the high entangled areas tends to be smaller than that of the low entangled areas. 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 low entangled areas rise up between the high entangled areas to form convex portions. 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 areas.

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 spacing 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 section between the orifice assembly sections 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 section 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 section may be less than 2 mm, in which case the highly entangled section is formed as a striated section.

Alternatively, the pattern forming nozzle may be a nozzle in which orifices having the above hole diameter are spaced apart from each other by 0.3 mm or more and 1.5 mm or less, and a portion equivalent to the orifice-free portion is formed by blocking some of the orifices.

When using a pattern forming nozzle, the water pressure of the water flow may be, for example, 1 MPa to 15 MPa, and in particular 3 MPa to 10 MPa.

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

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 multiple areas with a lower density than other areas (hereinafter, "low density areas"). The low density areas may be formed as open holes.

Specifically, the pattern formation support may be, for example, a plain weave, herringbone weave, twill weave, or satin weave 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. Supports made of fabrics with relatively thick filaments have convex portions at the intersections of the weft and warp threads, making it possible to form low-density regions. When such fabrics are used, the area of each low-density region is determined by the thickness of the threads that make up the fabric, and the spacing and pitch of the low-density regions are determined by the warp/weft density of the fabric.

Even when performing hydroentanglement processing using a pattern forming nozzle, it is preferable to perform the processing so that the total energy TE is within the above range.

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 bonding by electron beam irradiation or ultrasonic welding. When the heat treatment is performed, 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.

The heat treatment is, 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.

The heat treatment temperature (e.g., the temperature of the hot air) may be the temperature at which the component that constitutes the adhesive fiber and functions 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, if the adhesive fiber contains polyethylene as a component and polyethylene is the adhesive component, the heat treatment temperature may be 130°C to 150°C, and if polybutylene succinate is the adhesive component, the heat treatment temperature may be 120°C to 133°C.

(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.

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.

The wiper of this embodiment is used so that the wiping surface is the surface of fiber layer a. Fiber layer a contains a predetermined proportion 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 fiber layer a to the object. When nonwoven fabric is manufactured by hydroentanglement treatment, streaky water jet marks suitable for scraping off dirt are likely to be formed on the surface of fiber layer a, which is also the reason why the surface of fiber layer a is used as the wiping surface.

The wiper of this embodiment contains a nonwoven fabric whose stress index at 5% MD elongation is within the above range, so even when it is applied to an object and used repeatedly to wipe it, it is less likely to twist or stretch, and deformation or expansion of the interfiber voids caused by twisting or stretching is easily suppressed. Therefore, in the wiper of this embodiment, dirt that has once been trapped in the interfiber voids of the wiper is less likely to fall off, and excellent dirt collection properties are demonstrated.

The following fibers were prepared for use in this example.
Hydrophilic cellulose fiber A (in the table, "Rayon 1.7T"): viscose rayon having 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 having 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 having a fineness of 1.7 dtex and a 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 having a fineness of 1.0 dtex and a fiber length of 38 mm, with a water-repellent fiber treatment agent applied to the surface.

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 wet-laid nonwoven fabric (manufactured by Habix Co., Ltd.) consisting of 100% by mass of wood-derived pulp fibers (fineness of about 1.0 to 4.0 dtex, fiber length of about 0.8 mm to 4.5 mm) and having a basis weight of 17 g/ ^m2 .

Example 1
A first fiber web and a second fiber web were prepared by mixing 80% by mass of hydrophilic cellulose fiber A and 20% by mass of synthetic fiber a using a parallel carding machine with a target weight of about 24 g/ ^m2 .
A wetlaid nonwoven fabric 1 was laminated on the second fiber web as an intermediate fiber layer, and the second fiber web was laminated on the wetlaid 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 provided at intervals of 0.6 mm 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.

Next, the fiber web after the hydroentanglement treatment was heat-treated for 5 seconds using a hot air-penetrating heat treatment machine set at 135°C, and the fibers were bonded together by the sheath component of synthetic fiber a. The fiber web 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.

(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 and ratios of the fibers constituting the first fiber web and the second fiber web, the targeted weight of these fiber webs, and 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.

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

<Strength and elongation>
The strength and elongation were measured by subjecting a dry sample to a tensile test using a constant-speed tension-type tensile tester under the conditions of a sample width of 5 cm, a gripping 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 in accordance with JIS L 1913:2010 6.3. The tensile test was performed in the longitudinal direction (MD) and transverse direction (CD) of the nonwoven fabric as the tensile direction. The evaluation results are all 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.

<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 "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.

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 entanglement of the nonwoven fabric would be the wiping surface, with a load of 400 gf being applied. Wiping was performed by moving the wiper back and forth once on the surface of the white acrylic plate.

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 in the direction toward the left end of the dust dispersion area to rub the dust (white acrylic plate).
Then, move the wiper 500 mm in the direction toward the right end of the dust dispersion area,
The wiper was further moved 250 mm in the direction toward the left end of the dust dispersion area, and the wiper was made to reciprocate once.

After the wiper had gone 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 fresh, and the average value was taken as the dust collection rate.

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

Wiping was performed in a wet state by impregnating 250 parts by weight of distilled water per 100 parts by weight of nonwoven fabric. Wiping was performed with a weight of 400 gf applied to a wiper jig (product name: Quickle Wiper [tool body] head, manufactured by Kao Corporation) attached so that the area contributing to wiping was 26 cm vertically and 16 cm horizontally. Wiping was performed in the same manner as that used in the evaluation of dust collection ability above, by moving the wiper back and forth once over the hair. 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 fresh, and the average value was taken as the hair collection rate.

[Sesame capture ability (wet state)]
The sesame seed collection ability was evaluated by arranging 10 sesame seeds at intervals in three rows (3-4-3 rows) on a flooring and wiping them with a nonwoven fabric in the same manner as in the evaluation of hair collection ability (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 measured three times with the wiping surface of the nonwoven fabric fresh, and the average value was calculated as the sesame seed collection rate.

<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 reciprocation 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 %.

The evaluation results for each example and comparative example are shown in Tables 1 and 2.

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

Comparative Example 1 had a low stress index at 5% elongation in the MD because it did not have an intermediate fiber layer. Comparative Example 2 had a low stress index at 5% elongation in the MD 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. Comparative Examples 1 and 2 also showed a higher initial release rate than the examples, and were more likely to release liquid in the initial stage of wiping. 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 interfiber voids.

Comparative Example 3, like Comparative Example 2, contained polypropylene fibers, but these did not function as adhesive fibers, and because the polypropylene fibers were water-repellent and not easily entangled by hydroentanglement, the stress index at 5% elongation in the MD was low, and the dirt collection ability was also inferior to that of the Examples. Comparative Example 4 was made using the same fibers as in Example 1 in the same ratio, but because 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, the stress index at 5% elongation in the MD was low. Therefore, the dirt collection ability was inferior to that of Example 1.

Example 5
A first fiber web and a second fiber web were prepared by mixing 80% by mass of hydrophilic cellulose fiber A and 20% by mass of synthetic fiber a using a parallel carding machine with a target weight of about 24 g/ ^m2 .
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 with orifices having 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 were blocked so that the water stream was not sprayed from the orifices in the nozzle with a hole diameter of 0.12 mm arranged at 0.6 mm intervals, and a columnar water stream was sprayed from the nozzle onto the other surface. The hydroentanglement treatment was carried out so that the total energy TE of the sprayed water stream was 0.72 hw/kg/m.

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

Next, the fiber web after the hydroentanglement treatment was heat-treated for 5 seconds using a hot air-penetrating heat treatment machine set at 135°C, and the fibers were bonded together by the sheath component of synthetic fiber a. The fiber web 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.

Example 6
A 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.

[Hydroentanglement 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 threads/inch, a weft density of 16 threads/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.

The web after the hydroentanglement had a striped pattern in which parts having a herringbone pattern and parts not having a herringbone pattern were alternately arranged in the CD direction. This pattern was formed because the degree of entanglement differed between the parts hit by the water stream from the stripe pattern forming nozzle and the parts not hit by the water stream, and because the parts hit by the water stream were placed on a herringbone support.
(Example 7)
A 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.
[Hydroentanglement 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 having orifices with a hole diameter of 0.12 mm spaced at 0.6 mm intervals, 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.

The nonwoven fabric of Example 7 has the same fiber structure and basis weight as Example 1, but was manufactured with a higher total energy TE of the jetted water stream compared to Example 1. Due to the higher TE, some of the fibers (pulp) of the intermediate fiber layer were observed to fall off during the manufacture of Example 7, resulting in a lower stress index at 5% MD elongation in both dry and wet states than in Example 1, which is thought to have led to a decrease in dirt collection performance. Furthermore, the degree of entanglement between the fibers in Example 7 is higher than that of Example 1, and compared to Example 1, the movement of the fibers is restricted and the interfiber spaces are less likely to deform, which is presumably the reason why the dirt collection performance is lower than that of Example 1.

The nonwoven fabrics of Examples 5 and 6 were manufactured 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, making it difficult for the intermediate fiber layer to fall off as seen in Example 7, and the stress index at MD 5% elongation in both the 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 area, and there are irregularities due to the pattern formation, which are thought to also 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 irregularities are formed even in the area where the water stream is jetted, which is thought to have improved dirt collection performance.

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 weight 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 index at 5% elongation in the MD direction in a dry state (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.150 or more, and/or the stress index at 5% elongation in the MD direction in a wet state in which the nonwoven fabric is impregnated with ²⁵⁰ parts by mass of water per 100 parts by mass of the nonwoven fabric (N/5cm) is 0.050 or more;
Nonwoven fabric for objective wipers.
(Aspect 2)
The nonwoven fabric for an object wiper according to aspect 1, wherein the first fiber layer and the second fiber layer are both the fiber layer a.
(Aspect 3)
3. The nonwoven fabric for an object wiper according to claim 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 50 mass% or less of synthetic fibers.
(Aspect 5)
The nonwoven fabric for an objective wiper according to aspect 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)
A nonwoven fabric for an objective wiper according to aspect 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 Aspects 1 to 6, 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.
(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 Aspects 1 to 7.
(Aspect 9)
The nonwoven fabric for an objective wiper according to aspect 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;
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.
A method for producing a nonwoven fabric for object wipers, in which the stress index at 5% elongation in the MD direction in a dry state (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.150 or more, and/or the stress index 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 (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.050 or more.
(Aspect 11)
The manufacturing method of aspect 10, wherein the entanglement treatment includes spraying a water flow from a nozzle having an orifice assembly portion on a surface of the side 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 an object wiper according to any one of embodiments 1 to 9 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.

The nonwoven fabric of the present disclosure has a high stress index at 5% elongation in the MD, and is less likely to twist or stretch when rubbed against an object, suppressing deformation and expansion of interfiber voids. 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 larger size.

Claims (12)

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 composed of short fibers having a fiber length of 20 mm or less,
Each fiber layer is integrated by intertwining the fibers.
the stress index at 5% elongation in the MD direction in a dry state (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.150 or more, and/or the stress index at 5% elongation in the MD direction in a wet state in which the nonwoven fabric is impregnated with ²⁵⁰ parts by mass of water per 100 parts by mass of the nonwoven fabric (N/5cm) is 0.050 or more;
Nonwoven fabric for objective wipers. The nonwoven fabric for an object wiper according to claim 1, wherein the first fiber layer and the second fiber layer are both fiber layer a. The nonwoven fabric for object wipers according to claim 1 or 2, wherein the intermediate fiber layer is a wet-laid nonwoven fabric made of pulp. The nonwoven fabric for object wipers according to claim 1 or 2, wherein the fiber layer a contains more than 0% by mass and not more than 50% by mass of synthetic fibers. The nonwoven fabric for object wipers according to claim 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. The nonwoven fabric for an object wiper according to claim 4, wherein some 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. The nonwoven fabric for object wipers according to claim 1 or 2, in which the elongation in a dry state and/or the elongation in a wet state in which 100 parts by mass of the nonwoven fabric are impregnated with 250 parts by mass of water (%) is 85% or more. 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. The nonwoven fabric for object wipers according to claim 8, in which a low density region is formed in the highly entangled portion. 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;
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.
A method for producing a nonwoven fabric for object wipers, in which the stress index at 5% elongation in the MD direction in a dry state (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.150 or more, and/or the stress index 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 (N/5cm) divided by the basis weight of the nonwoven fabric (g/ ^m2 ) is 0.050 or more. The manufacturing method according to claim 10, wherein the entanglement treatment includes spraying a water flow from a nozzle having an orifice assembly on the side surface of the fiber web A, the nozzle having an orifice-free section having a width of 2 mm to 50 mm, the orifice-free section being disposed between the orifice assembly sections, to alternately form highly entangled sections and less entangled sections in the CD direction. 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.