US20030176132A1

US20030176132A1 - Nonwoven fabric for wiper

Info

Publication number: US20030176132A1
Application number: US10/358,331
Authority: US
Inventors: Hidetoshi Moriyasu; Masako Yokomizo; Sumito Kiyooka
Original assignee: Kuraray Co Ltd
Current assignee: Kuraray Co Ltd
Priority date: 2002-02-08
Filing date: 2003-02-05
Publication date: 2003-09-18
Also published as: DE60304615T2; AU2003200405A1; CN1436886A; DE60304615T3; TWI229158B; EP1342825B2; KR100494211B1; KR20030068043A; DE60304615D1; EP1342825A1; JP2003301359A; AU2003200405B9; EP1342825B1; SG128436A1; TW200303384A; JP4597487B2; CN1436886B; AU2003200405B2

Abstract

A nonwoven fabric contains extra-fine fibers which contain linear bonded regions and/or dot-like bonded regions, and non-bonded regions on a surface of the extra-fine fibers. The bonded regions account for from 10 to 80% of a surface area of the nonwoven fabric. A distance between neighboring bonded regions is at most 20 mm. The nonwoven fabric has an excellent ability to wipe off dirt including oily stains and persistent stains, it well follows even three-dimensionally patterned faces of the articles to be wiped with it. Its feel and its washing resistance are good.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a nonwoven fabric for a wiper, especially a wiper that has the ability to wipe off oily stains and caked persistent stains, and which exhibits little fluffing even when used repeatedly, and has good washing resistance.

2. Discussion of the Background

Various nonwoven fabric wipers of extra-fine fibers have been proposed and are now widely used. For example, a wiping material has been proposed, which is produced by hydroentangling and integrating heat-fusing fiber webs and extra-fine fiber webs followed by fusing the thus-entangled, heat-fusing fibers (JP-A 3-152255). The wiping material of this type may wipe off light dirt such as dust or the like but could not remove caked persistent stains. Another problem is that, when the wiping material is washed, its surface often fluffs up and some fibers often drop away from it. In addition, the wiping material is not flexible.

JP-A 5-56903 discloses a nonwoven fabric for wipers, which includes mechanically divided extra-fine fibers, which is bulky and which has a good wiping performance and long-term durability. The nonwoven fabric for wipers of this type is good for wiping off dust and the like, but is still unsatisfactory for removing persistent stains.

On the other hand, JP-A 6-14860 discloses a nonwoven fabric for wipers, which comprises mixed fibers of extra-fine fibers and thick fibers for improving its ability to remove caked stains. JP-A 7-67820 discloses a wiper produced by laminating and entangling spunlaid webs and paper sheets for improving its washing resistance. However, these wipers have a tough feel and are not flexible, and therefore they are not satisfactorily effective for wiping articles having a three-dimensionally patterned face.

Based on the above, it is clear that a need exists for a nonwoven fabric for wipers which has the ability to wipe off even oily stains and caked persistent stains and which has good washing resistance.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a nonwoven fabric for wipers which has the ability to wipe off even oily stains and caked persistent stains, which exhibits excellent cleaning capabilities on articles with three-dimensionally patterned faces, and which has good flexibility and good washing resistance.

This and other objects have been achieved by the present invention the first embodiment of which includes a nonwoven fabric, comprising:

extra-fine fibers comprising:

bonded regions in a form selected from the group consisting of linear bonded regions, dot-like bonded regions and mixtures thereof, and non-bonded regions on a surface of said extra-fine fibers;

wherein said bonded regions account for from 10 to 80% of a surface area of said nonwoven fabric; and

wherein a distance between neighboring bonded regions is at most 20 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows some examples of the pattern of the gravure roll that may be used in the present invention. A refers to the hills of the patterns, B refers to the valleys. [0014]
FIG. 2 shows one example of the surface of the nonwoven fabric of the present invention.[0015]

DETAILED DESCRIPTION OF THE INVENTION

Specifically, the present invention provides a nonwoven fabric for wipers which contains extra-fine fibers comprising, linear and/or dot-like bonded regions and non-bonded regions on its surface. The bonded regions account for from 10 to 80% of the surface area of the nonwoven fabric. The distance between the neighboring bonded regions is at most 20 mm. The percentage of bonded regions of surface area includes all values and subvalues therebetween, especially including 20, 30, 40, 50, 60 and 70%. The distance between neighboring bonded regions includes all values and subvalues between 0 and 20 mm, especially including 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19 mm. [0016]
The nonwoven fabric for wipers of the present invention contains extra-fine fibers. The surface of the nonwoven fabric comprises linear and/or dot-like bonded regions and non-bonded regions. Having the bonded regions and the non-bonded regions in its surface, the nonwoven fabric of the present invention has good cleaning capabilities and removes not only light dirt such as oily film or ink stains but also heavy dirt such as caked persistent stains. The woven fabric gives little fluff, and it is washable for repeated use. [0017]
Preferably, the single fiber fineness of the extra-fine fibers is at most 0.5 dtex, more preferably from 0.05 to 0.45 dtex. The single fiber fineness includes all values and subvalues therebetween, especially including 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 and 0.4 dtex. The extra-fine fibers may be, for example, directly spun fibers or those obtained from splittable conjugated fibers. Preferred are splittable conjugated fibers as extra-fine fibers. Especially preferable are extra-fine fibers which are prepared by dividing splittable conjugated fibers each having a nearly circular cross-sectional profile. This is because the cross-sectional profile of the extra-fine fibers derived from the splittable conjugated fibers of this type may have sharp shapes. Therefore, the nonwoven fabric that contains the extra-fine fibers is particularly suitable for removing oily stains. Such splittable conjugated fibers may be mechanically processed by hydroentangling or by needlepunching or may be chemically processed for dissolution and removal or for swelling and shrinkage to give the extra-fine fibers for use in the present invention. [0018]
The splittable conjugated fibers for the present invention may be formed of at least two different types of resin. The resin includes, for example, polyester polymers, polyolefin polymers, polyamide polymers, polystyrene polymers, polyacrylonitrile polymers, polyvinyl alcohol polymers, and ethylene-vinyl alcohol copolymers. One or more such polymers may be used for one component of the fibers, but these are not limiting. [0019]
The polyesters may be fiber-forming polyesters, which are formed of, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, phthalic acid, α,β-(4-carboxyphenoxy)ethane, 4,4-dicarboxydiphenyl, 5-sodium sulfoisophthalate; or aliphatic dicarboxylic acids such as azelaic acid, adipic acid, sebacic acid; or their esters; and diols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, polyethylene glycol, polytetramethylene glycol. Preferably, at least 80 mol % of the constituent units of the polyesters are ethylene terephthalate units. [0020]
The polyamides include, for example, aliphatic polyamides and semiaromatic polyamides of which the principal component is nylon 6, nylon 66 or nylon 12. They may contain a minor amount of a third component. [0021]
The conjugation morphology of these resin components for the conjugated fibers is not specifically limited. For example, two resin components may be conjugated: [0022]
1) into bicomponent fibers having a chrysanthemum-patterned cross-sectional profile in which the two resin components are alternately radially aligned; [0023]
2) into bicomponent fibers having a bimetal-patterned cross-sectional profile in which the two resin components are alternately layered; or, [0024]
3) into those having a sea/island patterned cross-sectional profile in which islands of one resin component are dispersed in a sea matrix of the other resin component. Of the splittable conjugated fibers, the chrysanthemum-patterned fibers and bimetal-patterned fibers are preferred for use herein, since the extra-fine fibers derived from them may have a sharp cross-sectional profile and therefore they are more effective for wiping off stains, especially for wiping off oily stains. [0025]
In the present invention, heat-fusing fibers may also be used. Due to the heat-fusing fibers, the shape stability of the nonwoven fabric according to the present invention is improved. Preferably, the proportion of the extra-fine fibers in the nonwoven fabric that contain heat-fusing fibers is at least 50%, preferably at least 60%, more preferably as least 70%, most preferably at least 80%. If it is smaller than 50%, the wiping capability of the nonwoven fabric will worsen. Especially when the nonwoven fabric is used for wiping off oily stains, the proportion of the splittable conjugated fibers therein is at least 80%, preferably at least 85%, more preferably at least 90% and most preferably 95%. Here, the heat-fusing fibers may be those of a single component, but are preferably side-by-side type or core-sheath type heat-fusing conjugated fibers of at least two resin components including those not fusing in heat treatment, since the non-fusing part of the fibers acts to retain the fiber strength. It is preferable that the melting point difference between the extra-fine fibers and the heat-fusing fibers that constitute the nonwoven fabric is at least 10° C., preferably at least 15° C., more preferably at least 20° C. and most preferably at least 25° C., so that the extra-fine fibers do not fuse with the heat-fusing fibers. [0026]
For the component for the heat-fusing fibers, various combinations may be mentioned, including, for example, 6-nylon/polyethylene, polypropylene/polyethylene, polypropylene/ethylene-vinyl acetate copolymer, polyester/polypropylene, polyester/polyethylene, 6-nylon/66-nylon; and high-density polyester/low-density polyester, but these are not limiting. [0027]
The nonwoven fabric for wipers of the present invention contains the extra-fine fibers mentioned above. For realizing excellent oil-removing capabilities and flexibility thereof, it is more preferable that the nonwoven fabric comprises 100% extra-fine fibers. The other fibers that may be combined with the extra-fine fibers in the present invention are not specifically limited, and may be any of various natural fibers and synthetic fibers. [0028]
The method of producing the nonwoven fabric for wipers of the invention is not specifically limited. For example, the nonwoven fabric may be formed of fiber webs that are prepared according to drylaying of carding, air-laying, spun-bonding or to wet-laying. The fiber webs are preferably random-laid webs, semirandom-laid webs or parallel-laid webs. [0029]
In the present invention, it is especially preferable that the fiber webs are formed by mixing various fibers such as extra-fine fibers and heat-fusing fibers mentioned above followed by processing them into fiber webs according to a carding process or an air-laying process. [0030]
In case where the extra-fine fibers are derived from splittable conjugated fibers by mechanically dividing them, the splittable conjugated fibers may be processed into the intended extra-fine fibers before they are formed into fiber webs. However, it is preferable that the splittable conjugated fibers are formed into fiber webs. After the resulting fiber webs are layered, they are mechanically processed by needle-punching or water-jet treatment, whereby the splittable conjugated fibers in the layered webs are divided to give the intended extra-fine fibers therein and the resulting extra-fine fibers are entangled at the same time through the treatment. In this process, the fiber-to-fiber bonding in the nonwoven fabric produced may be more strengthened. [0031]
The nonwoven fabric for wipers of the present invention has, in its surface, linear and/or dot-like bonded regions and non-bonded regions, and therefore has the ability to wipe off various dirt. Specifically, the non-bonded regions of the nonwoven fabric act to wipe off light dirt such as oily stains, and the bonded regions thereof act to wipe off caked persistent stains. Therefore, the nonwoven fabric exhibits its ability to wipe off various types of dirt. In the bonded regions, the fibers are partly fixed and are harder than those in the non-bonded regions. Therefore, the fibers in these regions are more effective for wiping off persistent stains. In addition, the bonded regions enhance the wiping performance with the nonwoven fabric. Due to having the fixed and toughened, bonded regions, the nonwoven fabric is, as a whole, toughened in some degree and it fits well to the hand while used for wiping operation. In addition, the nonwoven fabric also has the non-bonded regions and it keeps its softness. Accordingly, the nonwoven fabric well follows even three-dimensionally patterned faces of the articles to be cleaned with it. [0032]
Preferably, the bonded regions account for from 10 to 80% of the surface area of the nonwoven fabric. If the area of the bonded regions exceeds 80%, the nonwoven fabric will be too hard, and its feel to the hand and its wiping performance will worsen. In addition, the extra-fine fibers that are effective for wiping off light dirt such as oily stains will be covered with resin, and, as a result, the oil-wiping capability of the nonwoven fabric will worsen. On the other hand, if the area of the bonded regions is smaller than 10%, the fibers could not be satisfactorily fixed, and the surface of the nonwoven fabric will readily fluff up. If so, the nonwoven fabric could not resist to external physical shock such as washing, and the nonwoven fabric will be readily deformed and could not be used repeatedly. For better wiping capability, surface fluffing resistance and washing resistance of the nonwoven fabric, the bonded regions preferably account for from 10 to 50%, more preferably from 10 to 40% of the surface area of the nonwoven fabric. [0033]
The bonded regions of the nonwoven fabric may be formed by the use of a resin binder. For example, an emulsion resin binder may be used. The binder resin includes, for example, acrylic resins, acrylate copolymer resins, polyurethane resins, vinyl acetate copolymer resins, epoxy resins and styrene-acrylic copolymer resins, but is not limited to them. [0034]
The method of forming the bonded regions is not specifically limited. For example, the layered fiber webs may be partly bonded by emboss-rolling, or a resin binder may be transferred onto them through gravure-rolling. In the present invention, when a gravure roll is used, it is preferable that a pattern of continuous lines is formed. For example, the patterns of (I) to (III) in FIG. 1 are preferred as they improve the wiping capability and the design of the nonwoven fabric. In addition, it is desirable that at least a part of the fibers in the non-bonded regions of the nonwoven fabric may be embedded in the bonded regions for further improving the washing resistance of the nonwoven fabric. For this, the bonded regions are so formed that the distance between the neighboring bonded regions can be at most 20 mm, preferably at most 10 mm, more preferably from 2 to 8 mm. [0035]
In the present invention, the bonded regions may be formed to have a dot-like pattern of, for example, (IV) to (V) of FIG. 1. Having the pattern, the nonwoven fabric may be more flexible, and its ability to wipe off oily stains may be improved. The bonded regions may be a combination of the linear pattern and the dot-like pattern mentioned above, and various patterns may be employed for the bonded regions in accordance with the object thereof. [0036]
The binder having permeated through the thickness of the nonwoven fabric for wipers may be localized around both faces of the nonwoven fabric or may be uniformly permeated through the depth of the nonwoven fabric, depending on the drying condition after the binder resin application. [0037]
In any case where the binder resin has been localized around both faces of the nonwoven fabric or uniformly permeated through the depth thereof, the nonwoven fabric is prevented from fluffing up and its washing resistance is good. However, the binder resin localized around the faces of the nonwoven fabric is more effective for increasing the surface strength of the nonwoven fabric and for enhancing the wiping capability thereof to remove persistent strains. In this case the nonwoven fabric is soft and may fit well to the hand, and it may follow well even three-dimensionally patterned faces of the articles to be cleaned with it. To that effect, the wiping capability of the nonwoven fabric of the type is better. [0038]
In the nonwoven fabric for wipers of the present invention, it is preferable that at least a part of the individual fibers in the non-bonded regions are fixed by the bonded regions. Concretely, some fibers in the non-bonded regions of the nonwoven fabric are embedded in the bonded regions and are thereby fixed. In that condition, the nonwoven fabric well keeps its soft feel and its wiping capability, does not tend to exhibit so much fluffing, and its washing resistance is good. The nonwoven fabric of this type is most preferable for wipers. [0039]
The nonwoven fabric for wipers of the present invention has the above-mentioned, linear and/or dot-like bonded regions. For better wiping capability and better washing resistance of the nonwoven fabric, the bonded regions are so formed that the distance between the neighboring bonded regions can be at most 20 mm, preferably 2 to 10 mm. The distance between the neighboring bonded regions includes all values and subvalues therebetween, especially including 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19 mm. If the distance between the neighboring bonded regions is larger than 20 mm, the dimensional stability of the nonwoven fabric will be lower and the washing resistance thereof will also be lower. On the other hand, if the distance between them is smaller than 2 mm, the nonwoven fabric will have a hard feel. For keeping the oil-wiping capability of the extra-fine fibers as such and for ensuring better washing resistance of the nonwoven fabric, the distance between the neighboring bonded regions is most preferably from 2 to 8 mm. The distance between the neighboring bonded regions referred to in the present invention is the shortest distance therebetween, and it is obtained by measuring the shortest distance between the ends of the neighboring bonded regions. [0040]
The surface of the nonwoven fabric for wipers of the present invention may be flat, but is preferably further processed to have a perforated or embossed pattern for further enhancing the wiping capability of the nonwoven fabric. Specifically, owing to the synergistic effect of the embossed pattern and the bonded regions in the surface of the nonwoven fabric, the wiping capability of the nonwoven fabric is further improved. Another advantage thereof is that the nonwoven fabric thus having such an embossed surface well follows even three-dimensionally patterned faces of the articles to be wiped with it. The nonwoven fabric exhibits its wiping effect and, in addition, it is believed that the extra-fine fibers could more readily adhere to the surface of the nonwoven fabric to act to wipe off light dirt such as oily stains. In order to introduce an embossed pattern on the surface of the nonwoven fabric, hydroentangling can be employed. This method comprises spreading fiber webs on a belt support of a meshed resin net or metal net followed by applying water jets to them to thereby make the constituent fibers entangled. In this process, the height difference between the knuckles of the weft and those of the warp of the mesh belt is transferred onto the nonwoven fabric webs, and the nonwoven fabric thus processed is to have the intended embossed pattern on its surface. Alternatively, an embossing roll can be applied to the nonwoven fabric under pressure to thereby make the nonwoven fabric have the intended embossed pattern. In the present invention, hydroentangling is preferred because the resulting nonwoven fabric has a soft feel and keeps the embossed pattern well, even after washing. The nonwoven fabric having an embossed pattern may also be processed with a binder resin or the like to form the bonded regions therein. [0041]
The above-mentioned embossed pattern may be formed according to the methods mentioned hereinabove. For example, a nonwoven fabric having a pattern as in FIG. 2 may be used in the present invention. In a case where the nonwoven fabric having an embossed pattern is used in the present invention, it is preferable that the height difference between the hills and the valleys of the pattern is at least 20% of the thickness of the nonwoven fabric. If having a height difference of at least 20%, the surface area of the nonwoven fabric increases and therefore the length of contact with dirt is prolonged. Furthermore, the nonwoven fabric is more easily handled when used for wiping off dirt. In addition, the dirt to be wiped off may be physically caught by the hills of the embossed pattern of the nonwoven fabric and it may therefore well adhere to the nonwoven fabric. For these reasons, the wiping capability of the nonwoven fabric is much more enhanced. Moreover, some dirt may be kept caught in the valleys of the nonwoven fabric, and does not move to other articles that are cleaned with the nonwoven fabric to stain them. If the height difference is smaller than 20%, the surface of the nonwoven fabric will be flat, and if so, the nonwoven fabric could not well catch dirt and its wiping capability is inferior. The dirt once caught by the nonwoven fabric will move to other articles to stain them. [0042]
In the present invention, it is further preferable that the hills are formed to be both in the bonded regions and the non-bonded regions. The hills improve the wiping capability of the nonwoven fabric to well follow even the surfaces of non-flat articles to be wiped with it. In addition, the nonwoven fabric has much improved washing resistance. Moreover, the hills overlap with the bonded regions, and they are more hardened as the constituent fibers are concentrated therein. Accordingly, the thus-hardened hills are more effective for wiping off persistent stains. [0043]
As so mentioned hereinabove, the nonwoven fabric for wipers of this invention has bonded regions in which the surface of the nonwoven fabric is prevented from fluffing up. Even after washing, the entangled points of the constituent fibers of the nonwoven fabric do not shift and the nonwoven fabric can be used repeatedly. In a case where extra-fine fibers having edges are used, the nonwoven fabric is effective even for wiping off extremely fine dirt. The advantage of said nonwoven fabric is that it may well catch such fine dirt and may readily hold it on its surface. [0044]
The nonwoven fabric of the invention is usable for various wipers, which are, for example, for wiping noble metal articles such as jellies and for wiping dishes, tables, glass articles, electric appliances, furniture, gas cookers, etc. [0045]
The wipers to be obtained in the present invention are highly resistant to washing and can be used repeatedly, and therefore they are economical. [0046]
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only, and are not intended to be limiting unless otherwise specified. [0047]

EXAMPLES

In the Examples, the physical properties were measured according to the methods mentioned below. [0048]
Procedure of Measuring the Thickness of the Nonwoven Fabric: [0049]
The thickness of a sample is measured at 10 points under a load of 12 gf/cm[0050] ², and the data are averaged.
Height Difference in Embossed Pattern of Nonwoven Fabric: [0051]
A CCD laser dislocation sensor, LK-2000 (by Keyence) is used. With no load applied thereto, the thickness of a sample is measured at 6 hill peaks and 6 valley bottoms thereof. The data are averaged, and the difference between the two averages is divided by the thickness of the hill peaks. This indicates the height difference. [0052]

Example 1

Splittable conjugated fibers having a cross-sectional profile of alternately-layered nylon 6 and polyethylene terephthalate; (Kuraray's WRAMP, having a fineness of 3.8 dtex and a fiber length of 51 mm) alone (100%) were fed into a carding machine and processed into fiber webs. The resulting webs were processed by hydroentangling whereby the constituent fibers were divided into extra-fine fibers and the thus-split extra-fine fibers were entangled. After being processed by hydroentangling, the webs were coated with an acrylic resin (by Nippon Carbide) with a gravure roll having a waved pattern of II in FIG. 1. The area ratio of the pattern was 13%, the binder pitch was 3.2 mm, and the binder amount was 2 g/m[0053] ². The process gave a nonwoven fabric for wipers, having a mass per unit area of 80 g/m². The nonwoven fabric was observed, and was found to have linear bonded regions formed of the acrylic resin and non-bonded regions. The nonwoven fabric was observed in more detail, and it was confirmed that some ends of the extra-fine fibers in the non-bonded regions were embedded in the bonded regions and were fixed therein. The distance between the neighboring bonded regions was 3.0 mm. The data of the nonwoven fabric are given in Table 1.

Example 2

A nonwoven fabric for wipers having a mass per unit area of 80 g/m[0054] ²was produced in the same manner as in Example 1 except for the following changes: The webs obtained in Example 1 were processed by hydroentangling on a herringbone-patterned net so that the net pattern was transferred onto the webs, and the webs therefore had the embossed herringbone pattern. Thus obtained, the nonwoven fabric was observed, and was found to have linear bonded regions formed of the acrylic resin and non-bonded regions.
The nonwoven, fabric was observed in more detail, and it was confirmed that some ends of the extra-fine fibers in the non-bonded regions were embedded in the bonded regions and were fixed therein. The distance between the neighboring bonded regions was 3.0 mm. See Table 1. [0055]

Example 3

A nonwoven fabric for wipers having a unit weight of 80 g/m[0056] ²was produced in the same manner as in Example 2 except for the following changes: Splittable conjugated fibers having a cross-sectional profile of alternately-layered nylon 6 and polyethylene terephthalate (Kuraray's WRAMP, having a fineness of 3.8 dtex and a fiber length of 51 mm) 85% and core/sheath bicomponent binder fibers of which the core is polypropylene and the sheath is polyethylene (Daiwabo's NBF (H), 2. 2 dtex, 51 mm) 15% were fed into a carding machine and processed into fiber webs. The resulting webs were processed by hydroentangling whereby the splittable fibers were divided into extra-fine fibers and the resulting fibers were entangled. Thus processed, the webs were heat-set and the binder fibers therein were thereby fused. The distance between the neighboring bonded regions in the nonwoven fabric thus produced was 3.0 mm. See Table 1.

Comparative Example 1

A nonwoven fabric for wipers having a mass per unit area of 80 g/m[0057] ²was produced in the same manner as in Example 2, to which, however, the acrylic resin was not applied. See Table 1.

Comparative Example 2

A nonwoven fabric for wipers having a mass per unit area of 80 g/m[0058] ²was produced in the same manner as in Example 3, to which, however, the acrylic resin was not applied. See Table 1.

Comparative Example 3

Splittable conjugated fibers having a chrysanthemum-patterned cross-sectional profile of radially-aligned nylon 6 and polyethylene terephthalate (having a fineness of 2.2 dtex and a fiber length of 38 mm) 40% and polyethylene terephthalate fibers (having a fineness of 16.5 dtex and a fiber length of 51 mm) 60% were fed into a carding machine and processed into fiber webs. The resulting fibers webs were sprayed with an acrylic emulsion (15 g/m[0059] ²in terms of the solid content of the emulsion), and then heat-set at 150° C. for 3 minutes whereby the constituent fibers were bonded to each other to give a nonwoven fabric for wipers. See Table 1.

TABLE 1

mass per Bonded

unit area Thickness Regions Height Difference (%)

(g/m²) (mm) (%) in Embossed Pattern

Example 1 80 0.54 13 15

Example 2 80 0.52 13 38

Example 3 80 0.51 13 33

Comp. Ex. 1 80 0.57 0 41

Comp. Ex. 2 80 0.54 0 39

Comp. Ex. 3 150 2.6 100 10
The nonwoven fabrics for wipers obtained in the above-mentioned Examples and Comparative Examples were worked into wipers, and evaluated in the manner mentioned below. The results are given in Table 2. [0060]
Procedure for the Evaluation of Fluffing Resistance: [0061]
0.1 g of water is dropped onto a mirror face through a syringe. A wiper sample of 15 cm×15 cm is folded in four. An operator carries the wiper sample in the hand, and circularly moves it 10 times on the mirror face to wipe up the water. Then, the thus wiped mirror face is checked for the fiber remains thereon from the wiper sample. The wiper sample is evaluated in 5 ranks as follows: [0062]
5: No fluff found. [0063]
4: 1 to 5 fiber remains found. [0064]
3: 6 to 25 fiber remains found. [0065]
2: 26 to 50 fiber remains found. [0066]
1: 51 or more fiber remains found. [0067]
Procedure for Evaluation of Washing Resistance: [0068]
A square of 20 cm×20 cm is marked on a wiper sample, and the sample is washed 5 times according to the washing test method of JIS L1096. After washing, the shrinkage percentage of the sample is measured. Based on the CD (cross direction) shrinkage percentage thereof, the sample is evaluated in 3 ranks as follows: [0069]
A: less than +/−3%. [0070]
B: +/−3% to 5%. [0071]
C: more than +/−5%. [0072]
Procedure for Evaluation of Wiping Capability to Remove Oily Stains: [0073]
On a glass sheet, a circular seal is impressed with oily ink. A wiper sample of 15 cm×15 cm is folded in four. An operator carries the wiper sample in the hand, and completely wipes off the oily film with the wiper sample. The number of wiping operations that has been done before the film is completely wiped off is counted. [0074]
Procedure for Evaluation of Wiping Capability to Remove Persistent Stains: [0075]
The absorbance (A) of a glass sheet is measured. Moriwiper (by Sumiko Lubricant) is circularly applied to the glass sheet, and dried. After drying, the absorbance (B) of the glass sheet is measured. The glass sheet is set on the sample stand of a rubbing fastness tester. A wiper sample having a controlled water content of 100% is fitted to the friction prove of the tester, and this is moved once back and forth on the glass sheet to wipe off the stain. After this, the absorbance (C) of the glass sheet is measured. [0076]
According to the following equation, the degree of stain removal is obtained.[0077]
Degree of stain removal=(C−B)/(A−B)×100.
Procedure for Evaluation of Feel: [0078]
The feel of each wiper sample in the hand is evaluated in 3 ranks as follows: [0079]
A: Soft to the hand. [0080]
B: A little hard to the hand. [0081]
C: Hard to the hand. [0082]

TABLE 2

Oil Stains Persistent

Fluffing Washing Wiping Stains Wiping

Resistance Resistance Capability Capability Feel

Example 1 5 A 9 56.4 A

Example 2 5 A 9 57.0 A

Example 3 5 A 8 51.2 A to B

Comp. 2 C 8 6.6 B

Example 1

Comp. 3 B 9 10.2 B

Example 2

Comp. 3 to 4 B 7 16.4 C

Example 3
As is shown in Table 2, it is understood that the wipers formed of the nonwoven fabric of the present invention have good wiping capabilities and washing resistance. [0083]
As described in detail with reference to its preferred embodiments, the nonwoven fabric of the present invention exhibits excellent wiping capabilities to remove any and every dirt including oily stains and persistent stains under any cleaning conditions. While used for wiping off dirt, the wipers formed of the nonwoven fabric fluff up little. As their washing resistance is good, the wipers are repeatedly usable. [0084]
Japanese patent application 31914/2002, filed Feb. 8, 2002, is incorporated herein by reference. [0085]
Numerous modifications and variations on the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. [0086]

Claims

1. A nonwoven fabric, comprising:

extra-fine fibers comprising:

wherein a distance between neighboring bonded regions is at most 20 mm.

2. The nonwoven fabric according to claim 1, wherein said surface has an embossed pattern;

wherein a height difference between the hills and the valleys of said embossed pattern is at least 20% of the thickness of the nonwoven fabric.

3. The nonwoven fabric according to claim 1 which comprises 100% of extra-fine fibers.

4. A wiper made of the nonwoven fabric according to claim 1.

5. The nonwoven fabric according to claim 1, wherein a single fiber fineness of said extra-fine fibers is not more than 0.5 dtex.

6. The nonwoven fabric according to claim 1, wherein said extra-fine fibers are splittable conjugated fibers.

7. The nonwoven fabric according to claim 6, wherein said splittable conjugated fibers comprise at least two different types of resin.

8. The nonwoven fabric according to claim 7, wherein said resin is selected from the group consisting of polyester polymers, polyolefin polymers, polyamide polymers, polystyrene polymers, polyacrylonitrile polymers, polyvinyl alcohol polymers, ethylene-vinyl alcohol copolymers and mixtures thereof.

9. The nonwoven fabric according to claim 6, wherein said splittable conjugated fibers comprise two different types of resin components which are conjugated in the following manner:

1) into bicomponent fibers having a chrysanthemum-patterned cross-sectional profile in which the two resin components are alternately radially aligned;

2) into bicomponent fibers having a bimetal-patterned cross-sectional profile in which the two resin components are alternately layered; or

3) into bicomponent fibers having a sea/island patterned cross-sectional profile in which islands of one resin component are dispersed in a sea matrix of the other resin component.

10. The nonwoven fabric for wipers according to claim 1, comprising heat-fusing fibers.

11. The nonwoven fabric for wipers according to claim 10, wherein a melting point difference between said extra-fine fibers and said heat-fusing fibers is at least 10° C.

12. The nonwoven fabric for wipers according to claim 10, wherein said heat-fusing fibers comprise 6-nylon/polyethylene copolymer, polypropylene/polyethylene copolymer, polypropylene/ethylene-vinyl acetate copolymer, polyester/polypropylene copolymer, polyester/polyethylene copolymer, 6-nylon/66-nylon copolymer and high-density polyester/low-density polyester copolymer.

13. The nonwoven fabric for wipers according to claim 1, wherein said bonded regions of the nonwoven fabric are formed by using a resin binder.

14. The nonwoven fabric for wipers according to claim 1, wherein at least a part of said extrta-fine fibers in said non-bonded regions embedded in said bonded regions.