WO2013047885A1

WO2013047885A1 - Nonwoven fabric for moist towelette, method of manufacturing the non-woven fabric, and moist towelette using the same

Info

Publication number: WO2013047885A1
Application number: PCT/JP2012/075582
Authority: WO
Inventors: Takeshi BANDOU; Takahiro Ueda; Hiromi Yamada; Ayami Suga; Takayoshi Konishi; Toshio HIRAOKA
Original assignee: Unicharm Corporation
Priority date: 2011-09-30
Filing date: 2012-09-26
Publication date: 2013-04-04
Also published as: TW201326496A; JP5738144B2; TWI588314B; JP2013075107A

Abstract

A nonwoven fabric for a moist towelette includes absorbable fibers. A number of first ridges, first grooves, second ridges, and second grooves are formed on at least one surface of the nonwoven fabric. A top of the first ridge is higher than a top of the second ridge. The top of the second ridge is higher than a bottom of the second groove. The bottom of the second groove is higher than a bottom of the first groove. The first groove is located between the two adjacent first ridges. A plurality of second ridges and second grooves are located between the two adjacent first ridges, where the first groove is not located. A spacing between the two first ridges adjacent across the first groove is greater than a spacing between the two second ridges adjacent across the second groove.

Description

DESCRIPTION

NONWOVEN FABRIC FOR MOIST TOWELETTE, METHOD OF MANUFACTURING THE NON-WOVEN FABRIC, AND

MOIST TOWELETTE USING THE SAME

TECHNICAL FIELD

[0001]

The present disclosure relates to nonwoven fabrics for moist towelettes, methods of manufacturing such non- woven fabrics, and towelettes using the same.

BACKGROUND ART

[0002]

Japanese Patent No. 3183818 discloses a moist towelette layered product, in which layers having

hydrophobic and hydrophilic properties of fibers in the cross sectional direction of the nonwoven fabric are formed and takeout stability is improved by making an intermediate layer have water and which releases an appropriate amount of moisture during wiping off to prevent excessive moisture from remaining on an object to be wiped off.

[0003]

However, the inventor (s) has recognized that in the towelette layered product of Japanese Patent No. 3183818, due to slippage between sheets to inhibit a wiping-off operation by increasing the hydrophobic level of a layer due to the properties of a moist towelette, it might be difficult to obtain hydrophobic and water immersion levels between the layers and/or a definite structure for storing water. Further, due to use of fiber entanglement by physical energy of spunlace and/or the like as a method for fixation between the layers, a part between the layers might become indefinite to preclude definite exhibition of a layer structure. Furthermore, it might be difficult to be visually exhibited as a layer.

Further, wiping-off with a large amount of water and a small unwiped portion might be different.

SUMMARY

[0004]

At least one embodiment of the present invention provides a nonwoven fabric for a moist towelette, the nonwoven fabric comprising absorbable fibers. A

plurality of first ridges, first grooves, second ridges, and second grooves that extend in an elongation direction are formed on at least one surface of the nonwoven fabric. A height of a top of the first ridge is higher than a height of a top of the second ridge. The height of the top of the second ridge is higher than a height of a bottom of the second groove. The height of the bottom of the second groove is higher than a height of a bottom of the first groove. The first groove is located between the two adjacent first ridges. A plurality of second ridges and second grooves are located between the two adjacent first ridges, where the first groove is not located. A spacing between the two first ridges adjacent across the first groove is greater than a spacing between the two second ridges adjacent across the second groove.

[0005]

Further, at least one embodiment of the present invention provides a method for manufacturing the

nonwoven fabric for a moist towelette. The method comprising the steps of: supplying a mixture of fibers comprising absorbable fibers with water onto a substrate to form a web containing water on the substrate; jetting a water stream to a surface of the web from water stream nozzles placed in a cross direction of the web,

preferably at equal spacings, to entangle the fibers; jetting steam to the surface of the web, where the water stream has been jetted, from steam nozzles placed in the cross direction of the web, preferably at wider spacings than the spacings of the water stream nozzles; and drying the web to which the steam has been jetted. [0006]

Further, at least one embodiment of the present invention provides a moist towelette comprising the nonwoven fabric impregnated with a liquid.

BRIEF DESCRIPTION OF DRAWINGS

[0007]

FIG. 1 is a schematic enlarged perspective view of the nonwoven fabric according to at least one embodiment of the present invention.

FIG. 2 is a schematic enlarged transverse cross- sectional view of the nonwoven fabric of further

embodiments of the present invention.

FIG. 3 is a view that illustrates an example of a nonwoven fabric manufacturing apparatus for manufacturing a nonwoven fabric according to at least one embodiment of the present invention.

FIG. 4 is a view that illustrates an example of water stream nozzles.

FIG. 5 is a view for explaining the principle of entangling the fibers of a web with each other by water stream jetting.

FIG. 6 is a cross-sectional view of a web, to which a water stream is jetted, in a cross direction.

FIG. 7 is a view that illustrates an example of a steam nozzle.

FIG. 8 is a view for explaining the principle of disentangling the fibers of a web by jetting steam to form grooves and ridges.

FIG. 9 is a view that illustrates another example of the nonwoven fabric manufacturing apparatus for

manufacturing a nonwoven fabric according to at least one embodiment of the present invention.

FIG. 10 is a view that illustrates another example of the steam nozzle.

FIG. 11 represents a photograph of . the water stream- jetted surface (wet state) of a web jetted with water streams in Example 1.

FIG. 12 represents a photograph of the steam-j etted surface (wet state) of a web jetted with steam in Example 1.

FIG. 13 represents a photograph of the steam-jetted surface of a nonwoven fabric (dry state) obtained in Example 1.

FIG. 14 is a photograph of the steam-jetted surface of the nonwoven fabric (dry state) obtained in Example 3.

DESCRIPTION OF EMBODIMENTS

[0008]

At least one embodiment of the present invention provides a nonwoven fabric for a moist towelette, the nonwoven fabric comprising absorbable fibers. A number of first ridges, first grooves, second ridges, and second grooves that extend in an elongation direction are formed on at least one surface of the nonwoven fabric. A height of a top of the first ridge is higher than a height of a top of the second ridge. The height of the top of the second ridge is higher than a height of a bottom of the second groove. The height of the bottom of the second groove is higher than a height of a bottom of the first groove. The first groove is located between the two adjacent first ridges. A plurality of second ridges and second grooves are located between the two adjacent first ridges, where the first groove is not located. A spacing between the two first ridges adjacent across the first groove is greater than a spacing between the two second ridges adjacent across the second groove.

[0009]

The nonwoven fabric for a moist towelette according to at least one embodiment of the present invention has rough ridges and grooves (the first ridges and the first grooves) and minute ridges and grooves (the second ridges and the second grooves) and therefore it can remove relatively large fouling by entanglement with the rough grooves and can remove relatively small fouling by entanglement with the minute grooves. Specifically, in accordance with at least one embodiment of the present invention, rough to micro fouling can be removed with one sheet .

[0010]

Some embodiments of the present invention will be described below with reference to the drawings, but the present disclosure is not limited to the descriptions of the drawings.

[0011]

FIG. 1 is the schematic enlarged perspective view of the nonwoven fabric according to at least one embodiment of the present invention.

In the nonwoven fabric 1 according to at least one embodiment of the present invention, a plurality of first ridges 3, first grooves 4, second ridges 5, and second grooves 6 that extend in an elongation direction Y are formed on at least one surface (e.g., the upper surface) of the nonwoven fabric. The height h₃ of the top 3T of the first ridge is higher than the height h₅ of the top 5T of the second ridge; the height h₅ of the top 5T of the second ridge is higher than the height of the bottom 6B of the second groove; and the height he of the bottom 6B of the second groove is higher than the height h₄ of the bottom 4B of the first groove. As used herein, a

"height" refer to the distance to the opposite surface (e.g., the lower surface) of the non-woven fabric, in a direction perpendicular to the opposite surface. When the opposite surface has ridges and grooves, the heights h₃, h , h₅, and h refer to distances to the tops of the most projecting ridges on the opposite surface. The first groove 4 is located between the two adjacent first ridges 3, 3. A plurality of second ridges 5 and second grooves 6 are located between the two adjacent first ridges 3, 3, where the first groove 4 is not located.

Spacing d₃ between the two first ridges 3, 3 adjacent across the first groove 4 is greater than spacing d₅ between the two second ridges adjacent across the second groove.

[0012]

Specifically, the nonwoven fabric according to at least one embodiment of the present invention has the rough ridges and grooves (the first ridges and the first grooves) and the minute ridges and grooves (the second ridges and the second grooves) . Relatively large fouling can be removed by entanglement with the rough grooves and relatively small fouling can be removed by entanglement with minute grooves. Specifically, in accordance with at least one embodiment of the present invention, rough to micro fouling can be removed with one sheet.

[0013]

A- difference (h₃ - h₅) between the height h₃ of the top of the first ridge and the height hs of the top of the second ridge is preferably 0.1 mm or more, more

preferably 0.12-0.70 mm, further preferably 0.15-0.50 mm. A property of scraping away fouling is deteriorated and it is difficult to achieve more bulkiness when the difference (h₃ - h₅) is too low whereas damage to a sheet is high resulting in decreased sheet strength and fibers easily falling out when it is too high.

[0014]

Spacing d₃ ' between the two first ridges 3, 3

adjacent across the second ridges 5 and the second grooves 6 is preferably 3 mm or more, more preferably 4.0-8.0 mm, further preferably 4.5-6.0 mm. When the spacing d₃ ' is too short, it is difficult to form the region R₂ where the second ridges and the second grooves are located. In contrast, when the spacing d₃ ' is too long, the number of ridges and grooves is decreased to deteriorate a property of scraping away fouling and to preclude maintenance of bulkiness.

[0015]

A difference (h₅ - h₆) between the height h₅ of the top of the second ridge and the height h₆ of the bottom of the second groove is preferably 0.05-0.10 mm, more preferably 0.06-0.09 mm, further preferably 0.07-0.08 mm. It becomes paper-like to cause hard feeling when the difference (h₅ - h₆) is too low. In contrast, a contact area becomes small to deteriorate a finishing wiping effect when the difference (h₅ - h₆) is too high.

The heights h₃, h₄, h₅, and h₆ can be determined by the microphotograph of a cross section. The method to determine the heights is as follows:

A sample of a nonwoven fabric (dried product) was impregnated with liquid nitrogen, frozen, then cut with a razor, and returned to ordinary temperature, followed by photographing it at a magnification of 50 times using an electron microscope (e.g., VE7800 from Keyence

Corporation) to measure the heights h₃, h₄, h₅, and h6- [0016]

Spacing d₅ between the two second ridges 5, 5

adjacent across the second groove 6 is preferably 0.3-1.0 mm, more preferably 0.4-0.8 mm, further preferably 0.5- 0.7 mm. It is difficult to form concavities and

convexities when the spacing d₅ is too short, whereas a portion having weakly entangled fibers is formed causing great unevenness in sheet strength when it is too long.

[0017]

A difference (h₃ - h₄) between the height h₃ of the top of the first ridge and the height h₄ of the bottom of the first groove is preferably 0.15-0.60 mm, more

preferably 0.17-0.55 mm, further preferably 0.20-0.50 mm. An effect of taking fouling by entanglement is decreased when the difference (h₃ - h₄) is too short whereas

maintenance of an applied shape becomes difficult and the amount of fibers falling out is increased when it is too long.

[0018]

In accordance with at least one embodiment of the present invention, the apparent density in the dry state in the nonwoven fabric in the region Ri where the first ridges and the first groove are located is lower than the apparent density in the dry state in the region R₂ where the second ridges and the second grooves are located.

The apparent density in the dry state in the

nonwoven fabric in the region Ri where the first ridges and the first groove are located is preferably 0.030-0.10 g/cm³, more preferably 0.04-0.09 g/cm³, further preferably 0.05-0.08 g/cm³. The number of fibers on the convexity is excessively decreased causing weakening when the apparent density in the region Ri is too low whereas the number of fibers is excessively increased to preclude fouling from entering and to deteriorate wiping-off properties when it is too high.

The apparent density in the dry state in the region

R₂ where the second ridges and the second grooves are located is preferably 0.12-0.20 g/cm³, more preferably 0.13-0.19 g/cm³, further preferably 0.14-0.18 g/cm³. A contact area is reduced to cause roughened wiping, which might not be suitable for finishing wiping, when the apparent density in the region R₂ is too low whereas it is easy to become rough to touch when it is too high.

The term "dry state" as stated herein means

"absolutely dry state," i.e., a state after leaving at rest in a constant-temperature bath at 105°C for 1 hour.

The apparent density is measured as follows:

The cross section of the nonwoven fabric was

macrophotographed at a magnification of 50 times or more by a microscope or the like, the number of fibers per unit area of thickness of region Ri or R₂ x 0.5 mm in width was measured, and the weight of the fibers was calculated from the result to calculate the apparent density.

[0019]

Since the nonwoven fabric according to a preferred embodiment of the present invention has the region R₂ in which the apparent density is high and the region Ri in which the apparent density is low, when it is impregnated with a liquid to obtain moist towelettes, most of the liquid is gathered in the region R₂ in which the apparent density is high while the liquid is not present in a large amount in the region Ri in which the apparent density is low. Specifically, in the nonwoven fabric according to a preferred embodiment of the present invention, the liquid-receiving portion defined by the region R2 where the second ridges and the second grooves are located and the non-receiving portion defined by the region Ri where the first ridges and the first groove are located are visually distinguishable from each other upon the impregnation with the liquid. Examples of the liquid may include distilled water and mixed solutions of antiseptic agents such as propylene glycol and paraben.

When the liquid is water, the state in which the water between fibers is concentrated on small ridge portions and no water is present on large ridge portions due to a density gradient, so that fouling can be wiped off while preventing excessive moisture from remaining on a

surface, where an object to be wiped off is present, by floating the fouling with the water from the small ridge portions to absorb the water in the large ridge portions when the object is wiped off.

[0020]

The first ridges 3 and the first grooves 4 can be formed by jetting steam and the second ridges 5 and the second grooves 6 can be formed by jetting a water stream. The details of the formation methods are described below.

[0021]

FIG. 2 illustrates the schematic enlarged transverse cross-sectional view of the nonwoven fabric of further embodiments of the present invention. In the nonwoven fabric illustrated in FIG. 2, at least one third ridge 7 is further formed between the two adjacent first ridges

3, 3 where the second ridges 5 and the second grooves 6 are not located. In the embodiment illustrated in FIG. 2, the two third ridges 7 are formed between the two adjacent first ridges 3, 3; however, one third ridge may be formed or three or more third ridges may be formed. When two or more third ridges 7 are formed between the two adjacent first ridges 3, 3, a third groove 8 is present between the two adjacent third ridges 7. The height h₇ of the top 7T of the third ridge 7 is higher than the height h₅ of the top 5T of the second ridge 5. The height h₇ of the top 7T of the third ridge 7 may be equal to or different from the height h₃ of the top 3T of the first ridge 3. Preferably, the height h₇ of the top 7T of the third ridge 7 is equal to the height h₃ of the top 3T of the first ridge 3. The height h₈ of the bottom 8B of the third groove 8 may be equal to or different from the height h₄ of the bottom 4B of the first groove 4.

Preferably, the height he of the bottom 8B of the third groove 8 is equal to the height i of the bottom 4B of the first groove 4.

[0022]

The nonwoven fabric according to at least one embodiment of the present invention contains absorbable fibers (i.e., fibers that can absorb water)..

Preferably, 30% or more, more preferably 35% or more, further preferably 40% or more, of fibers

constituting the nonwoven fabric are absorbable fibers.

All the fibers constituting the nonwoven fabric may also be absorbable fibers.

Such absorbable fibers which can be used in various embodiments of the present invention include: wood pulp such as chemical, semichemical, and mechanical pulp from coniferous and broadleaf trees; mercerized and cross- linked pulp prepared by chemical treatment of the wood pulp; non-wood-based fibers from hemp, cotton, and the like; cellulosic fibers such as regenerated fibers such as rayon fibers; and polyvinyl alcohol fibers. The absorbable fibers preferably contain cellulose.

Fibers other than the absorbable fibers include synthetic fibers such as polyethylene, polypropylene, polyester, and polyamide fibers.

[0023]

The fibers constituting the nonwoven fabric

preferably have fiber lengths of 20 mm or less, more preferably 1-20 mm, even more preferably 1-15 mm, further preferably 2-12 mm. Their homogeneous dispersion in water does not easily degrade when the fiber lengths are too long. In contrast, yield is decreased during making paper and hydroentanglement easily decreases strength when they are too short.

The fiber length is measured using a fiber size analyzer "Kajaani FiberLab."

[0024]

The nonwoven fabric according to at least one embodiment of the present invention can be manufactured by a method comprising the steps of:

supplying a mixture of fibers comprising absorbable fibers with water onto a substrate to form a web

containing water on the substrate;

jetting a water stream to a surface of the web from water stream nozzles placed in a cross direction of the web (direction that is perpendicular to the direction of travel of the web) , preferably at equal spacings, to entangle the fibers;

jetting steam to the surface of the web, where the water stream has been jetted, from steam nozzles placed in the cross direction of the web, preferably at wider spacings than the spacings of the water stream nozzles; and

drying the web to which the steam has been jetted.

[0025]

The method for manufacturing the nonwoven fabric according to at least one embodiment of the present invention will be described in detail below.

FIG. 3 is a view that illustrates an example of a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric according to at least one embodiment of the present invention.

[0026]

First, a mixture of fibers comprising absorbable fibers with water is supplied onto the substrate of a web formation conveyer 16 by a raw material supply head 11 and accumulated on the substrate. The substrate

preferably has such permeability that steam is permeable. For example, a wire mesh, a blanket, or the like may be used in the substrate.

[0027]

The fibers accumulated on the substrate and

containing the water are moderately dehydrated by suction boxes 13 to form a web 30. The web 30 is passed between two water stream nozzles 12 which are placed on the substrate and the two suction boxes 13 which are placed in the positions facing the water stream nozzles 12

across the substrate and collect water jetted from the water stream nozzles 12. At this time, high-pressure water streams are jetted to the web 30 from the water stream nozzles 12 to form the second ridges and the second grooves on the web 30.

[0028]

An example of the water stream nozzles 12 is

illustrated in FIG. 4. The water stream nozzle 12 jets toward the web 30 a plurality of water streams 31 lined in the cross direction (CD) of the web 30. As a result, a plurality of grooves 32 that are lined in the cross direction of the web 30 and extend in a machine direction (MD) are formed on the web 30. The grooves 32 correspond to the second grooves 6.

[0029]

Further, when the web 30 receives the water streams, the grooves 32 are formed on the web 30 as mentioned above and the fibers of the web 30 are entangled with each other to increase the strength of the web 30. The principle of entangling the fibers of the web 30 with each other when the web 30 receives the water streams is described referring to FIG. 5, but the principle does not limit the present invention.

[0030]

As illustrated in FIG. 5, when the water stream nozzle 12 jets the water stream 31, the water stream 31 passes through the substrate 41. Thereby, the fibers of the web 30 are drawn mainly in a part 42 where the water stream 31 passes through the substrate 41. As a result, the fibers of the web 30 are gathered towards the part 42 where the water stream 31 passes through the substrate 41, to entangle the fibers with each other.

[0031]

Even when steam is jetted to the web 30 in a later step, formation of a hole, breaking, and blowing off are inhibited by entangling the fibers of the web 30 with each other to increase the strength of the web 30.

Further, the wet strength of the web 30 can be increased even when no paper strong agent is added to the raw materials.

[0032]

The water stream jetted from the water stream nozzle 12 is a high-pressure water stream.

The amount of the energy of the water stream in the case of jetting the water stream to the web 30 is

preferably 0.125-1.324 k /m².

The amount of the energy of the water stream is calculated by the following expression:

amount of energy (kW/m²) of water stream = 1.63 x jet pressure (Kg/cm²) x jet flow rate (m³/min) / treatment speed (m/min) / 60

wherein jet flow rate (m³/min) = 750 x total orifice opening area (m²) x jet pressure (Kg/cm² ) ⁰ - ⁴⁹⁵.

The amount of the energy of the water stream is an amount of the energy of the water stream on the surface of the web.

When the amount of the energy of the water stream is less than 0.125 k /iti², the strength of the web 30 may not increase much. When the amount of the energy of the water stream is higher than 1.324 kW/m², the web 30 may become too much rigid and the web 30 may be prevented from becoming much more bulky by high-pressure steam.

[0033]

A distance between the bore of the water stream nozzle 12 and the upper surface of the web 30 is

preferably 5.0-20.0 mm. When the distance between the top of the water stream nozzle 12 and the upper surface of the web 30 is shorter than 5.0 mm, the contexture of the web may be easily degraded by the force of high- pressure water and fibers bounced by the force of the water stream are prone to adhere to the nozzle may occur. Further,, when the distance between the bore of the water stream nozzle 12 and the upper surface of the web 30 is longer than 20.0 mm, treatment efficiency is

significantly decreased resulting in the entanglement of fibers may occur.

[0034]

The water stream nozzles 12 preferably have bore diameters of 90-150 μπι. When the bore diameters of the water stream nozzles 12 are too small, the nozzles may become easily clogged. Further, when the bore diameters of the water stream nozzles 12 are too large, treatment efficiency may deteriorate.

[0035]

The bore pitches (i.e., spacings or distances between the centers of adjacent bores) of the water stream nozzles 12 are preferably 0.3-1.0 mm. When the bore pitches of the water stream nozzles 12 are too short, withstanding pressures of the nozzles may decrease resulting in damage to them. Further, when the bore pitches of the water stream nozzles 12 are too long, fiber entanglement may be insufficient.

[0036]

The cross section of the web 30 in the cross direction after passing between the two water stream nozzles 12 and the two suction boxes 13 is illustrated in FIG. 6. The second ridges and the second grooves are formed on the upper surface of the web 30 by high- pressure water streams. Depending on the conditions of jetting the water streams, similar ridges and grooves are also formed on the surface opposite to a surface to which the water streams are jetted (not illustrated) .

[0037]

Then, the web 30 is passed between the two steam nozzles 14 placed on the substrate and two suction boxes 13 that are placed in the position opposite to the steam nozzles 14 across the substrate and suck steam jetted from the steam nozzles 14. At this time, the steam is jetted from the steam nozzles 14 to the web 30 to form the first ridges 3 and the first grooves 4 on the upper surface (i.e., the surface closer to the steam nozzles 14) . When the nonwoven fabric manufacturing apparatus illustrated in FIG. 3 is used, the surface of the web to which the steam is jetted is the same as the surface to which the water streams are jetted. Depending on the conditions of jetting water streams, ridges and grooves are also formed on the surface opposite to the surface to which the water streams are jetted. When the ridges and grooves are formed on the surface opposite to the surface to which the water streams are jetted, the apparatus may also be remodeled to jet steam to the surface opposite to the surface to which the water streams are jetted.

[0038]

An example of the steam nozzles 14 is illustrated in

FIG. 7. The steam nozzle 14 jets toward the web 30 a plurality of steams 51 lined in the cross direction (CD) of the web 30. As a result, a plurality of grooves 52 that are lined in the cross direction of the web 30 and extend in a machine direction (MD) are formed on the upper surface of the web 30. The grooves 52 correspond to the first grooves 4. [0039]

The principle of forming the first ridges 3 and the first grooves 4 when the steam is jetted to the web 30 is described referring to FIG. 8, but the principle does not limit the present invention.

[0040]

As illustrated in FIG. 8, when the steam nozzle 14 jets the steams 51, the steams 51 hit the substrate 41. Unlike the water streams 31 jetted from the water stream nozzles 12, most of the steams 51 are rebounded by the substrate 41. Thereby, the fibers of the web 30 are rolled up and disentangled. Further, the fibers of the web 30 are pushed aside by the steams 51 to form the first grooves 4. The fibers pushed aside are moved to gather to the cross direction side of the part 53 of the substrate 41, hit by the steams 51, and the first ridges 3 are formed.

[0041]

Since the strength of web 30 is enhanced by the high-pressure water streams, it is not necessary to place on the web 30 a net for preventing the web 30 from being blown off by the steams 51 when the steams 51 are jetted to the web 30. Accordingly, the efficiency of treatment of the web 30 by the steams 51 is increased. Further, since it is not necessary to place the above-described net, the maintenance of the nonwoven fabric manufacturing apparatus 10 and the cost of manufacturing a nonwoven fabric can be reduced.

[0042]

The steam jetted from the steam nozzle 14 is high- pressure steam. The pressure of the steam jetted from the steam nozzle 14 is preferably 0.3-1.5 MPa. When the pressure of the steam is lower than 0.3 MPa, the first ridges having sufficient heights may not be formed. When the steam pressure of the high-pressure steam is higher than 1.5 MPa, a hole may be formed in the web 30 or the web 30 may be broken or blown off. The pressure of the steam is a pressure at the nozzle.

[0043]

Suction force at which the substrate sucks the web by a suction box 13 which sucks the steam jetted from the steam nozzles 14 is preferably -1 to -12 kPa. When the suction force of the substrate is lower than -1 kPa, all of the steam cannot be sucked, which results in an explosion. Further, when the suction force of the substrate is higher than -12 kPa, a problem that there are many fibers falling in the suction may occur.

[0044]

A distance between the bore of the steam nozzle 14 and the upper surface of the web 30 is preferably 1.0-10 mm. When the distance between the bore of the steam nozzle 14 and the upper surface of the web 30 is shorter than 1.0 mm, a problem that a hole is formed in the web 30 or the web 30 is broken or blown off may occur.

Further, when the distance between the bore of the steam nozzle 14 and the upper surface of the web 30 is longer than 10 mm, force for forming the grooves on the surface of the web 30 by the high-pressure steam is dispersed to deteriorate the efficiency of forming the grooves on the surface of the web 30.

[0045]

The bore diameter of the steam nozzle 14 is

preferably larger than the bore diameter of the water stream nozzle 12 and the bore pitch of the steam nozzle 14 is larger than the bore pitch of the water stream nozzle 12. As a result, the first ridges and the first grooves can be formed on the web 30 by the high-pressure steam jetted from the steam nozzle 14 while keeping the second ridges and the second grooves formed by the high- pressure water stream jetted from the water stream nozzle 12, as illustrated in FIG. 1. In the web 30, the region R₂ where the plurality of second ridges and second grooves formed by the high-pressure water stream are present is a region where the apparent density of the web 30 is high and the region Ri where the first ridges and the first grooves are formed by the high-pressure steam is a region where the apparent density of the web 30 is decreased by the high-pressure steam.

[0046]

The bore diameter of the steam nozzle 14 is

preferably 150-600 μπι. When the bore diameter of the steam nozzle 14 is too small, energy is insufficient and fibers may not sufficiently be pushed aside. Further, when the bore diameter of the steam nozzle 14 is too large, energy becomes excessive and damage to the

substrate may occur.

[0047]

The bore pitch (i.e., spacing or distance between the centers of adjacent bores) of the steam nozzle 14 is preferably 3.0-8.0 mm. When the bore pitch of the steam nozzle 14 is too short, the second ridges and the second grooves vanish. In contrast, when the bore pitch of the steam nozzle 14 is too long, the number of ridges and grooves is decreased to deteriorate a property of

scraping away fouling and to preclude maintenance of bulkiness .

[0048]

The first ridges and the first grooves are formed on the upper surface of the web 30 by the high-pressure steam and not-illustrated concavities and convexities corresponding to the pattern of the substrate 41 may also be formed on the under surface of the web 30 (surface closer to the substrate 41 of the web 30) . Ridges and grooves may also be formed on the under surface of the web by high-pressure water streams or by high-pressure steam.

[0049]

Then, the web 30 is transferred to a web

transportation conveyer 18 by a suction pickup 17, as illustrated in FIG. 3. The web 30 is further transferred to a web transportation conveyer 19 and thereafter transferred to a dryer drum 20. The dryer drum 20 is, e.g., a yankee dryer, and the web 30 is attached to the drum heated to about 160°C by steam to dry the web 30. The dried web 30 is wound up as a nonwoven fabric by a wind-up machine 22.

[0050]

In the case of the nonwoven fabric according to embodiment as illustrated in FIG. 1, the bore pitches of the water stream nozzles 12 are equal to spacing d₆ between the two adjacent second grooves while the bore pitches of the steam nozzles 14 are equal to spacing d₄ between the two adjacent first grooves.

The nonwoven fabric according to at least one embodiment as illustrated in FIG. 2 is obtained when steam is jetted to the position of the arrow described in the upper part of FIG. 2. Specifically, letting that the spacing between the two first grooves 4, 4 adjacent across the second ridges and the second grooves is pi and the spacing between the first groove 4 and the third groove 8 adjacent across the third ridge 7 is P₂, the nonwoven fabric according to the embodiment as

illustrated in FIG. 2 is obtained when the bore pitches of the steam nozzles 14 are repeatedly pi / p₂ / P₂ and the pitches of the water stream nozzles are equal to the spacing d6 between the adjacent two second grooves.

When the bore pitches of the steam nozzles 14 are two kinds of spacing as illustrated in FIG. 2, the longer spacing is preferably 3.0-8.0 mm while the shorter spacing is preferably 2.0-2.5 mm.

[0051]

FIG. 9 is the view that illustrates another example of the nonwoven fabric manufacturing apparatus for manufacturing a nonwoven fabric according to at least one embodiment of the present invention.

In the nonwoven fabric manufacturing apparatus 10 as illustrated in FIG. 9, ridges and grooves having short pitches are formed on the upper surface (hereinafter referred to as "B surface") of the web 30 by high- pressure water streams from the water stream nozzles 12 while ridges and grooves having short pitches are also formed on the opposite, lower surface (hereinafter referred to as "A surface") of the web 30 by adjusting the conditions of jetting the water streams. The web jetted with the water streams is transferred to a web transportation conveyer 18 by a suction pickup 17, then transferred to a web transportation conveyer 19, and then transferred to a dryer drum 20. The dryer drum 20 is, e.g., a yankee dryer, and the web 30 is attached to the drum heated by steam to dry the web 30. In the nonwoven fabric manufacturing apparatus as illustrated in FIG. 9, the moisture content of the web 30 can be adjusted prior to entering into a steam jetting step. The moisture content of the web 30 prior to entering into the steam jetting step is preferably 10-45%. As used herein, moisture content (%) is the gram of water contained based on the total mass of 100 g of the web 30 containing the water. When the moisture content of the web 30 is too low, hydrogen bonding strength between the fibers of the web 30 is increased to make energy needed for

disentangling the fibers of the web 30 by steam as mentioned below very high. In contrast, when the

moisture content of the web 30 is too high, energy needed for drying the web 30 to predetermined moisture content or less by steam as described below is excessive.

[0052]

Then, the web 30 is sent to the steam jetting step. In the steam jetting step, the web 30 is moved onto the mesh-like outer peripheral surface of a suction drum 15 which is cylindrical. When this occurs, steam is jetted to the web 30 from the steam nozzle 14 placed above the outer peripheral surface of the suction drum 15. Two lines of the steam nozzles 14 are illustrated in FIG. 9; however, one line may be placed or three or more lines may be placed. In the case of the nonwoven fabric manufacturing apparatus of FIG. 9, the surface of the web to which steam is jetted is the surface opposite to the surface to which water streams are jetted (A surface) . The suction drum 15 includes a suction apparatus and steams sprayed from the steam nozzles 14 are sucked in the suction apparatus. The first ridges 3 and the first grooves 4 are formed on the A surface of the web 30 by the steams jetted from the steam nozzles 14.

[0053]

An example of the steam nozzles 14 placed above the suction drum 15 is illustrated in FIG. 10. FIG. 10 illustrates an example in which the steam nozzles 14 are in one line. The steam nozzle 14 sprays toward the web 30 a plurality of steams 51 lined in the cross direction (CD) of the web 30. As a result, a plurality of grooves

52 that are lined in the cross direction of the web 30 and extend in a machine direction (MD) are formed on the A surface of the web 30. The grooves 52 correspond to the first grooves 4.

[0054]

The web jetted with the steam is transferred to a dryer drum 21 as illustrated in FIG. 9. The dryer drum 21 is also, for example, a yankee dryer and the web 30 is attached to the drum heated by steam to dry the web 30. It is desirable that the web 30 passed through the dryer drum 21 is sufficiently dried, and specifically, the moisture content of the web 30 passed through the dryer drum 21 is preferably 5% or less. The dried web 30 is wound up as a nonwoven fabric by a wind-up machine 22.

[0055]

In the high-pressure hydroentanglement treatment, fibers are entangled and a web is tightened (increasing density) to increase the strength of the web. In the high-pressure steam treatment, fibers are disentangled (decreasing density) to make a nonwoven fabric more bulky. In this case, since the amount of energy is higher in the high-pressure water stream treatment, only a part of the nonwoven fabric is disentangled and the fibers can be applied with a shape without being

scattered in the high-pressure steam treatment.

In accordance with at least one embodiment of the present invention, a liquid is concentrated on a portion which is bulky (having a small specific volume) due to a capillary phenomenon during impregnation with the liquid by performing high-pressure steam spraying treatment of a part of a hydroentangled nonwoven fabric to form a concavity and convexity structure having different sheet bulks. A part having a large amount of the liquid and a part having a small amount are present in series in a cross section, so that an area that releases the liquid and an area that absorbs the liquid are generated during wiping off and, as a result, a sheet by which fouling is adequately removed and less moisture remains can be formed.

[0056]

The nonwoven fabric according to at least one embodiment of the present invention is used to make a moist towelette. The moist towelette can be made by impregnating the nonwoven fabric with a liquid. The amount of the liquid is, for example, around 3 times the dry mass of the nonwoven fabric. The liquid is typically distilled water and, in addition, examples of the liquid may include mixed solutions of antiseptic agents such as propylene glycol and paraben.

EXAMPLES

[0057]

Example 1

A nonwoven fabric was produced using the nonwoven fabric manufacturing apparatus 10 of FIG. 9, as described below.

A raw material for a nonwoven fabric, containing 70% by weight of bleached softwood kraft pulp (NBKP)

(Canadian Freeness Standard (cfs) 700 cc) and 30% by weight of rayon having a fineness of 1.1 dtex and a fiber length of 7 mm (Corona manufactured by Daiwabo Rayon Co., Ltd. ) , was prepared. The raw material for a nonwoven fabric was supplied onto the substrate (OS80 manufactured by Nippon Filcon Co., Ltd.) of a web formation conveyer using the raw material supply head 11 and the suction box was used to dehydrate the raw material for a nonwoven fabric to form a web. The basis weight (dry basis) of the web was 50 g/m².

Then, high-pressure water streams were jetted to the web using two high-pressure water stream nozzles. In this case, the high-pressure water stream energy of one high-pressure water stream nozzle was 0.142 kW/m² and, since the high-pressure water streams were jetted to the web using the two high-pressure water stream nozzles, the high-pressure water stream energy of the high-pressure water streams jetted to the web was 0.284 kW/m². The bore diameters of the high-pressure water stream nozzles were 92 μπι, the bore pitch was 0.5 mm, and the travel speed of the web was 70 m/min. By jetting the water streams, a ridge and groove structure having a pitch of 0.5 mm was formed on the water stream-j etted surface of the web and a ridge and groove structure having a pitch of 0.5 mm was also formed on the surface opposite to the water stream- jetted surface.

The web jetted with the water streams was sent to a steam jetting step via two web transportation conveyers and a yankee dryer.

In the steam jetting step, high-pressure steam was jetted to the surface opposite to the water stream-j etted surface of the web using two steam nozzles. In this case, the pressure of the high-pressure steam was 0.7

Pa, the temperature of the high-pressure steam was about 175°C, a distance between the bore of the steam nozzle and the upper surface of the web was 2.0 mm, the bore

diameter of the steam nozzle was 500 μπι, a bore pitch was 4.0 mm, and the travel speed of the web was 70 m/min.

Then, the web was sent to a wind-up machine via the yankee dryer and wound up as a nonwoven fabric.

[0058]

FIG. 11 is the photograph of the water stream-j etted surface (wet state) of the web jetted with the water streams.

FIG. 12 is the photograph of the steam-jetted

surface (wet state) of the web jetted with the steam.

FIG. 13 is the photograph of the steam-jetted

surface of the obtained nonwoven fabric (dry state) .

[0059]

The nonwoven fabric mass per unit area, the height h₃ (in the dry state) of the first ridge, the height h₅ (dry state) of the second ridge, the apparent density of the region Ri, the apparent density of the region R₂, the dry tensile strength, the dry tensile elongation, the wet tensile strength, and the wet tensile elongation of the obtained nonwoven fabric were measured. The measurement results are listed in Table 1.

Further, the obtained nonwoven fabric was

impregnated with distilled water amounting to three times the dry mass of the nonwoven fabric to make a moist towelette. An artificial fouling wiping-off property test was conducted using the made moist towelette to measure a fouling removal ratio on the high-pressure steam-jetted surface. The measurement result is listed in Table 1.

[0060]

Example 2

A nonwoven fabric was produced in the same

conditions as in Example 1 except that a steam nozzle pitch was changed to 3 mm. The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

[0061]

Comparative Example 1 A nonwoven fabric was produced on the same

conditions as in Example 1 except that steam was not jetted. The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

[0062]

Comparative Example 2

A nonwoven fabric was produced on the same

conditions as in Example 1 except that a steam nozzle pitch was changed to 2 mm. Ridges and grooves formed on an A surface by jetting water streams vanished by jetting steam, and only first ridges and first grooves formed by jetting the steam were present but second ridges and second grooves formed by jetting water streams were not present on the A surface of the obtained nonwoven fabric. The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

[0063]

Example 3

A nonwoven fabric was produced in the same

conditions as in Example 1, except that steam nozzle pitches were at 5 mm / 2 mm / 5 mm / 2 mm. FIG. 14 is the photograph of the steam-jetted surface of the

obtained nonwoven fabric (photographed in the state where it was wound up in roll form) . The obtained nonwoven fabric was evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

[0064]

Table 1

[0065]

Web moisture content prior to jetting steam, web moisture content after jetting steam, web moisture

content during winding, a nonwoven fabric mass per unit area, a dry thickness, the height h₃ of a first ridge (dry state) , the height h₅ of a second ridge (dry state) , the apparent density of a region Ri, the apparent density of a region R₂, a dry tensile strength, a dry tensile

elongation, a wet tensile strength, a wet tensile

elongation, and a fouling removal ratio were measured as described below.

[0066]

[Web Moisture Content Prior to Jetting Steam]

A web dried by the dryer drum 20 is sampled in a size of 30 cm x 30 cm, the outlet mass (Wi) of the dryer drum 20 is measured, and the sample piece is then left at rest in a constant-temperature bath at 105°C for 1 hour and absolutely dried, followed by measuring its mass (Di) . Web moisture content (%) prior to jetting steam is

calculated according to the following expression. The web moisture content prior to jetting steam is the mean value of ten measurement values.

Web moisture content (%) prior to jetting steam = (Wi - Di) / Wx x 100

[0067]

[Web Moisture Content after Jetting Steam]

A web jetted with high-pressure steam from the steam nozzle 14 on one suction drum 15 is sampled in a size of 30 cm x 30 cm, its mass (W₂) after passing through the steam nozzle 14 is measured, and the sample piece is then left at rest in a constant-temperature bath at 105°C for 1 hour and absolutely dried, followed by measuring its mass (D₂) - The web moisture content (%) after jetting steam is calculated according to the following expression. The web moisture content after jetting steam is the mean value of ten measurement values.

Web moisture content (%) after jetting steam = (W₂ - D₂) / W₂ x 100

[0068]

[Web Moisture Content during Winding]

A web wound up is sampled in a size of 30 cm x 30 cm, its mass (W₃) after the winding is measured, and the sample piece is then left at rest in a constant- temperature bath at 105°C for 1 hour and absolutely dried, followed by measuring its mass (D₃) . The web moisture content (%) during winding is calculated according to the following expression. The web moisture content during winding is the mean value of the measurement values in N = 10.

Web moisture content (%) during winding = (W₃ - D₃) / W₃ x 100

[0069]

[Nonwoven Fabric Mass Per Unit Area]

A nonwoven fabric mass per unit area was calculated by dividing the mass D₃ (g) of the sample absolutely dried when the web moisture content during winding was

measured, by its area (0.09 m²) . The nonwoven fabric mass per unit area is the mean value of ten measurement values .

[0070]

[Height h₃ of First Ridge (dry state) and Height h₅ of Second Ridge (dry state) ]

Corporation) to measure the heights h₃ of the first ridges (dry state) and the heights h₅ of the second ridges (dry state) . The reason why the sample was frozen was because the thickness is prevented from being varied by

compression during cutting with the razor.

[0071]

[Apparent Densities of Regions R_x and R₂] The cross section of the nonwoven fabric was

macrophotographed at a magnification of 50 times or more by a microscope or the like, the number of fibers per unit area of thickness of region Ri or R₂ x 0.5 mm in width was measured, and the weight of the fibers was calculated from the result to calculate the apparent density .

[0072 ]

A difference between the apparent densities is calculated according to the following expression:

Difference (%) between apparent densities = ( p₂ - pi )

wherein pi is the apparent density of the region Ri ; and p₂ is the apparent density of the region R₂ .

[0073 ]

[Dry Tensile Strength]

Strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the machine direction of the web, and strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the cross direction of the web, were cut from the produced nonwoven fabric to make samples for measurement. The tensile strengths of the samples for measurement in the machine and cross directions, which samples were each three, were measured using a tensile testing machine

(manufactured by Shimadzu Corporation, Autograph, Model: AGS-lkNG) including a load cell having a maximum load capacity of 50 N on the conditions of a grip distance of 100 mm and a tension speed of 100 mm/min. The mean value of the tensile strengths of the samples for measurement in the machine and cross directions, which samples were each three, was regarded as a dry tensile strength in the machine and cross directions.

[0074 ]

[Dry Tensile Elongation]

Strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the machine direction of the web, and strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the cross direction of the web, were cut from the produced nonwoven fabric to make samples for measurement. The tensile elongations of the samples for measurement in the machine and cross directions, which samples were each three, were measured using the tensile testing machine (manufactured by Shimadzu Corporation, Autograph, Model: AGS-lkNG) including the load cell having a maximum load capacity of 50 N on the conditions of a grip distance of 100 mm and a tension speed of 100 mm/min. A tensile elongation is a value obtained by dividing a maximum elongation (mm) when a sample for measurement is pulled by the tensile testing machine, by a grip distance (100 mm) . The mean value of the tensile elongations of the samples for measurement in the machine and cross

directions, which samples were each three, was regarded as a dry tensile elongation in the machine and cross directions.

[0075]

[Wet Tensile Strength]

Strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the machine direction of the web, and strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the cross direction of the web, were cut from the produced nonwoven fabric to make samples for measurement, and the samples for measurement were impregnated with water amounting to 2.5 times the mass of the samples for measurement (water content of 250%) . The tensile

strengths of the samples for measurement in the machine and cross directions, which samples were each three, were measured using the tensile testing machine (manufactured by Shimadzu Corporation, Autograph, Model: AGS-lkNG) including the load cell having a maximum load capacity of 50 N on the conditions of a grip distance of 100 mm and a tension speed of 100 mm/min. The mean value of the tensile strengths of the samples for measurement in the machine and cross directions, which samples were each three, was regarded as a wet tensile strength in the machine and cross directions.

[0076]

[Wet Tensile Elongation]

Strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the machine direction of the web, and strip-shaped test pieces having a width of 25 mm, of which the longitudinal direction is the cross direction of the web, were cut from the produced nonwoven fabric to make samples for measurement, and the samples for measurement were impregnated with water amounting to 2.5 times the mass of the samples for measurement (water content of 250%). The tensile

elongations of the samples for measurement in the machine and cross directions, which samples were each three, were measured using the tensile testing machine (manufactured by Shimadzu Corporation, Autograph, Model: AGS-lkNG) including the load cell having a maximum load capacity of 50 N on the conditions of a grip distance of 100 mm and a tension speed of 100 mm/min. The mean value of the tensile elongations of the samples for measurement in the machine and cross directions, which samples were each three, was regarded as a wet tensile elongation in the machine and cross directions.

[0077]

[Fouling Removal Ratio]

As simulated fouling, a paste consisting of 12.6% by weight of carbon black, 20.8% by weight of beef tallow highly hydrogenated oil, and 66.6% by weight of liquid paraffin was prepared. The paste was mixed with hexane at a weight ratio of 85:15. Onto a glass plate, 0.05 mL of hexane-diluted paste was dropped. After drying for 24 hours in a room at high temperature and high humidity (20°C, humidity of 60%), its color was scanned with a scanner. A wiping-off test (once) was conducted with a friction coefficient measuring apparatus from Tester Sangyo Co., Ltd. on the conditions of 150 mm/min and a load of 60 g. After the test, a change in color was scanned by the scanner and a rate of change in the color of an area of 16.9 mm x 16.9 mm in a scanned area was calculated according to the following expression and regarded as a fouling removal ratio.

Fouling removal ratio (%) = (C₀ - Ci) / C₀ x 100 wherein Co is a color prior to wiping off; and Ci is a color after wiping off.

A greater color removal ratio can be considered to mean that more fouling can be removed. The measurement is performed for N = 3, and the mean value of three measurements is regarded as a fouling removal ratio.

[0078]

Some embodiments of the present invention are also defined by way of the following non-limiting features CI to C16, Jl to J16, and Ul to U16, which are not

necessarily specific to the detailed embodiments

described above.

CI. A nonwoven fabric for a moist towelette, the nonwoven fabric comprising an absorbable fiber, wherein a plurality of first ridges, first

grooves, second ridges, and second grooves that extend in an identical direction are formed on at least one surface of the nonwoven fabric;

a height of a top of the first ridge is higher than a height of a top of the second ridge;

the height of the top of the second ridge is higher than a height of a bottom of the second groove;

the height of the bottom of the second groove is higher than a height of a bottom of the first groove;

the first grooves each are located between two adjacent first ridges; a plurality of second ridges and second grooves are located between two adjacent first ridges, where the first groove is not located; and

spacing between the two first ridges adjacent across the first groove is more than spacing between the two second ridges adjacent across the second groove.

C2. The nonwoven fabric according to CI, wherein an apparent density in a dry state of the nonwoven fabric in a region where the first ridges and the first groove are located is lower than an apparent density in a dry state of the nonwoven fabric in a region where the second ridges and the second grooves are located.

C3. The nonwoven fabric according to CI, wherein a difference between the height of the top of the first ridge and the height of the top of the second ridge is 0.1 mm or more.

C4. The nonwoven fabric according to CI, wherein the absorbable fiber contains cellulose.

C5. The nonwoven fabric according to CI, wherein a liquid-receiving portion defined by the region where the second ridges and the second grooves are located and a non-receiving portion defined by the region where the first ridges and the first groove are located are visually distinguishable from each other upon

impregnation with a liquid.

C6. The nonwoven fabric according to CI, wherein

30% or more of fibers constituting the nonwoven fabric are absorbable fibers.

C7. The nonwoven fabric according to CI, wherein the apparent density in the dry state of the nonwoven fabric in the region where the first ridges and the first groove are located is 0.030-0.10 g/cm³; and the apparent density in the dry state of the nonwoven fabric in the region where the second ridges and the second grooves are located is 0.12-0.20 g/cm³. C8. The nonwoven fabric according to Cl, wherein spacing between the two first ridges adjacent across the second ridges and the second grooves is 3 mm or more.

C9. The nonwoven fabric according to Cl, wherein the fibers constituting the nonwoven fabric have fiber lengths of 20 mm or less.

CIO. The nonwoven fabric according to Cl, wherein a difference between the height of the top of the second ridge and the height of the bottom of the second groove is 0.05-0.10 mm.

Cll. The nonwoven fabric according to Cl, wherein the spacing between the two second ridges adjacent across the second groove is 0.3-1.0 mm.

C12. The nonwoven fabric according to Cl, wherein a difference between the height of the top of the first ridge and the height of the bottom of the first groove is 0.15-0.60 mm.

C13. The nonwoven fabric according to Cl, wherein a third ridge is further formed between two adjacent first ridges where the second ridges and the second grooves are not located; and

a height of a top of the third ridge is higher than the heights of the tops of the second ridges.

C14. The nonwoven fabric according to Cl, wherein the first ridges and the first grooves are formed by jetting steam; and

the second ridges and the second grooves are formed by jetting a water stream.

C15. A method for manufacturing the nonwoven fabric for a moist towelette according to claim 1, the method comprising the steps of:

supplying a mixture of fibers comprising absorbable fibers with water onto a substrate to form a web containing water on the substrate;

jetting a water stream to the web from water stream nozzles placed in a cross direction of the web at equal spaces to entangle the fibers;

jetting steam to the web, to which the water stream has been jetted, from steam nozzles placed in the cross direction of the web at wider spaces than the spaces of the water stream nozzles; and

drying the web to which the steam has been jetted.

C16. A moist towelette comprising the nonwoven fabric according to CI impregnated with a liquid.

Jl . A nonwoven fabric for a moist towelette, the nonwoven fabric comprising an absorbable fiber, wherein a plurality of first ridges, first grooves, second ridges, and second grooves that extend in an identical direction are formed on at least one surface of the nonwoven fabric;

the height of the top of the first ridge is higher than the height of the top of the second ridge;

the height of the top of the second ridge is higher than the height of the bottom of the second groove;

the height of the bottom of the second groove is higher than the height of the bottom of the first groove; the first groove is located between the two adjacent first ridges;

the plurality of second ridges and second grooves are located between the two adjacent first ridges, where the first groove is not located; and

J2. The nonwoven fabric according to Jl, wherein an apparent density in a dry state in the nonwoven fabric in a region where the first ridges and the first groove are located is lower than an apparent density in a dry state in a region where the second ridges and the second grooves are located.

J3. The nonwoven fabric according to Jl or J2, wherein

a difference between the height of the top of the first ridge and the height of the top of the second ridge is 0.1 mm or more.

J4. The nonwoven fabric according to any one of Jl to J3_f wherein

the absorbable fiber contains cellulose.

J5. The nonwoven fabric according to any one of Jl to J4, wherein

a liquid-receiving portion and a non-receiving portion can visually be confirmed during impregnation with a liquid.

J6. The nonwoven fabric according to any one of Jl to J5, wherein

30% or more of fibers constituting the nonwoven fabric are absorbable fibers.

J7. The nonwoven fabric according to any one of Jl to J6, wherein

the apparent density in the dry state in the

nonwoven fabric in the region where the first ridges and the first groove are located is 0.030-0.10 g/cm³; and

the apparent density in the dry state in the

nonwoven fabric in the region where the second ridges and the second grooves are located is 0.12-0.20 g/cm³.

J8. The nonwoven fabric according to any one of Jl to J7, wherein

spacing between the two first ridges adjacent across the second ridges and the second grooves is 3 mm or more.

J9. The nonwoven fabric according to any one of Jl to J8, wherein

the fibers constituting the nonwoven fabric have fiber lengths of 20 mm or less.

J10. The nonwoven fabric according to any one of Jl to J9, wherein

a difference between the height of the top of the second ridge and the height of the bottom of the second groove is 0.05-0.10 mm. Jll. The nonwoven fabric according to any one of Jl to J10, wherein

the spacing between the two second ridges adjacent across the second groove is 0.3-1.0 mm.

J12. The nonwoven fabric according to any one of Jl to Jll, wherein

a difference between the height of the top of the first ridge and the height of the bottom of the first groove is 0.15-0.60 mm.

J13. The nonwoven fabric according to any one of Jl to J12, wherein

a third ridge is further formed between the two adjacent first ridges where the second ridges and the second grooves are not located; and

the height of the top of the third ridge is higher than the heights of the tops of the second ridges.

J14. The nonwoven fabric according to any one of Jl to J13, wherein

the first ridges and the first grooves are formed by jetting steam; and

the second ridges and the second grooves are formed by jetting a water stream.

J15. A method for manufacturing the nonwoven fabric for a moist towelette according to Jl, the method

comprising the steps of:

supplying a mixture of fibers containing absorbable fibers with water onto a substrate to form a web

containing water on the substrate;

jetting a water stream to the web from water stream nozzles placed in the cross direction of the web at equal spacings to entangle the fibers;

jetting steam to the web, to which the water stream is jetted, from steam nozzles placed in the cross

direction of the web at wider spacings than the spacings of the water stream nozzles; and

drying the web to which the steam is jetted.

J16. A moist towelette comprising the nonwoven fabric according to any one of Jl to J14 impregnated with a liquid.

Ul. A nonwoven fabric for a moist towelette, the nonwoven fabric comprising absorbable fibers, wherein

a number of first ridges, first grooves, second ridges, and second grooves that extend in an elongation direction are formed on at least one surface of the nonwoven fabric;

the first groove is located between the two adjacent first ridges;

a plurality of second ridges and second grooves are located between the two adjacent first ridges, where the first groove is not located; and

a spacing between the two first ridges adjacent across the first groove is greater than a spacing between the two second ridges adjacent across the second groove.

U2. The nonwoven fabric according to Ul, wherein an apparent density in an absolutely dry state of the nonwoven fabric in a region where the first ridges and the first groove are located is lower than an apparent density in a dry state of the nonwoven fabric in a region where the second ridges and the second grooves are located.

U3. The nonwoven fabric according to Ul, wherein a difference between the height of the top of the first ridge and the height of the top of the second ridge is 0.1 mm or more.

U4. The nonwoven fabric according to Ul, wherein the absorbable fibers contain cellulose. U5. The nonwoven fabric according to Ul, wherein a liquid-receiving portion defined by the region where the second ridges and the second grooves are located and a non-receiving portion defined by the region where the first ridges and the first groove are located are visually distinguishable from each other upon

impregnation with a liquid.

U6. The nonwoven fabric according to Ul, wherein

30% or more of fibers constituting the nonwoven fabric are the absorbable fibers.

U7. The nonwoven fabric according to Ul, wherein the apparent density in the dry state of the nonwoven fabric in the region where the first ridges and the first groove are located is 0.030-0.10 g/cm³; and the apparent density in the dry state of the nonwoven fabric in the region where the second ridges and the second grooves are located is 0.12-0.20 g/cm³.

U8. The nonwoven fabric according to Ul, wherein the spacing between the two first ridges adjacent across the second ridges and the second grooves is 3 mm or more.

U9. The nonwoven fabric according to Ul, wherein the fibers constituting the nonwoven fabric have fiber lengths of 20 mm or less.

U10. The nonwoven fabric according to Ul, wherein a difference between the height of the top of the second ridge and the height of the bottom of the second groove is 0.05-0.10 mm.

Ull. The nonwoven fabric according to Ul, wherein the spacing between the two second ridges adjacent across the second groove is 0.3-1.0 mm.

U12. The nonwoven fabric according to Ul, wherein a difference between the height of the top of the first ridge and the height of the bottom of the first groove is 0.15-0.60 mm.

U13. The nonwoven fabric according to Ul, wherein at least one third ridge is further formed between the two adjacent first ridges where the second ridges and the second grooves are not located; and

U14. The nonwoven fabric according to Ul, wherein a plurality of ridges and grooves having the same pitches as the second ridges and the second grooves are formed on a surface opposite to the one surface .

U15. A method for manufacturing the nonwoven fabric for a moist towelette comprising absorbable fibers, wherein

the first groove is located between the two adjacent first ridges;

a spacing between the two first ridges adjacent across the first groove is greater than a spacing between the two second ridges adjacent across the second groove,

the method comprising the steps of:

supplying a mixture of fibers comprising absorbable fibers with water onto a substrate to form a web containing water on the substrate; jetting a water stream to a surface of the web from water stream nozzles placed in a cross direction of the web to entangle the fibers;

jetting steam to the surface of the web, where the water stream has been jetted, from steam nozzles placed in the cross direction of the web; and

drying the web to which the steam has been j etted .

U16. A moist towelette comprising the nonwoven fabric according to Ul impregnated with a liquid.

This application claims the benefit of Japanese Application No. 2011-218057, the entire disclosure of which is incorporated by reference herein.

INDUSTRIAL APPLICABILITY

[0079]

The nonwoven fabric according to at least one embodiment of the present invention can preferably be used for producing a moist towelette.

REFERENCE SIGNS LIST

[0080]

1 Nonwoven fabric

3 First ridge

4 First groove

5 Second ridge

6 Second groove

10 Nonwoven fabric manufacturing apparatus

11 Raw material supply head

12 Water stream nozzle

13 Suction box

14 Steam nozzle

15 Suction drum

16 Web formation conveyer

17 Suction pick up

18, 19 Web transportation conveyer , 21 Dryer drum

Wind-up machine

Web

High-pressure water stream Groove

Substrate

High-pressure steam

Groove

Claims

1. A nonwoven fabric for a moist towelette, the nonwoven fabric comprising absorbable fibers, wherein

a plurality of first ridges, first

the first groove is located between the two adjacent first ridges;

spacing between the two first ridges adjacent across the first groove is more than spacing between the two second ridges adjacent across the second groove .

2. The nonwoven fabric according to claim 1, wherein

an apparent density in an absolutely dry state of the nonwoven fabric in a region where the first ridges and the first groove are located is lower than an apparent density in an absolutely dry state of the nonwoven fabric in a region where the second ridges and the second grooves are located, wherein the absolutely dry state is a state after leaving at rest in a constant- temperature bath at 105°C for 1 hour.

3. The nonwoven fabric according to claim 1 or 2, wherein

4. The nonwoven fabric according to any one of claims 1 to 3, wherein

the absorbable fiber contains cellulose.

5. The nonwoven fabric according to any one of claims 1 to 4, wherein

a liquid-receiving portion defined by the region where the second ridges and the second grooves are located and a non-liquid-receiving portion defined by the region where the first ridges and the first groove are located are distinguishable from each other upon

impregnation with a water-based liquid.

6. The nonwoven fabric according to any one of claims 1 to 5, wherein

30% or more of fibers constituting the nonwoven fabric are absorbable fibers.

7. The nonwoven fabric according to any one of claims 1 to 6, wherein

the apparent density in an absolutely dry state of the nonwoven fabric in the region where the first ridges and the first groove are located is 0.030- 0.10 g/cm³, wherein the absolutely dry state is a state after leaving at rest in a constant-temperature bath at 105°C for 1 hour; and

the apparent density in an absolutely dry state of the nonwoven fabric in the region where the second ridges and the second grooves are located is 0.12- 0.20 g/cm³.

8. The nonwoven fabric according to any one of claims 1 to 7, wherein

the spacing between the two first ridges adjacent across the second ridges and the second grooves is 3 mm or more.

9. The nonwoven fabric according to any one of claims 1 to 8, wherein

the fibers constituting the nonwoven fabric have fiber lengths of 1 to 20 mm.

10. The nonwoven fabric according to any one of claims 1 to 9, wherein

a difference between the height of the top of the second ridge and the height of the bottom of the second groove is 0.05-0.10 mm.

11. The nonwoven fabric according to any one of claims 1 to 10, wherein

12. The nonwoven fabric according to any one of claims 1 to 11, wherein

13. The nonwoven fabric according to any one of claims 1 to 12, wherein

at least one third ridge is further formed between the two adjacent first ridges where the second ridges and the second grooves are not located; and

14. The nonwoven fabric according to any one of claims 1 to 13, wherein

the first ridges and the first grooves are formed by jetting steam; and

the second ridges and the second grooves are formed by jetting a water stream.

15. A method for manufacturing the nonwoven fabric for a moist towelette according to claim 1, the method comprising the steps of:

jetting a water stream to a surface of the web from water stream nozzles placed in a cross direction of the web at egual spacings to entangle the fibers;

jetting steam to the surface of the web, where the water stream has been jetted, from steam nozzles placed in the cross direction of the web at wider spacings than the spacings of the water stream nozzles; and

drying the web to which the steam has been jetted.

16. A moist towelette comprising the nonwoven fabric according to any one of claims 1 to 14 impregnated with a liquid.