US20150313439A1

US20150313439A1 - Wiping cloth for removing microbes

Info

Publication number: US20150313439A1
Application number: US14/649,750
Authority: US
Inventors: Shoji Yabuzaki; Toshihiko Yagi
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 2012-12-06
Filing date: 2013-05-29
Publication date: 2015-11-05
Also published as: WO2014087687A1; JPWO2014087687A1; JP5856623B2

Abstract

A wiping cloth removes microbes and is capable of picking up dirt from the wiped surface of an object and trapping the dirt into the cloth to ensure the retention of the trapped dirt. The wiping cloth is made of a fabric including 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm³/gr or more.

Description

TECHNICAL FIELD

This disclosure relates to a wiping cloth for removing microbes.

BACKGROUND

Wiping cloths are conventionally used for the cleaning of glasses and lenses, and as the electronic information society has rapidly developed, they have become increasingly used to clean screens of electronic devices, as typified by liquid crystal display screens and, accordingly, required to have high dirt removal performance. The requirement, however, cannot be satisfied by conventional cotton or paper wiping cloths because lint and dust should be avoided in the electronic field. In addition to the electronic information field, wiping cloths have also become increasingly used at home and in hospitals and, consequently, there has been a demand for wiping cloths with a high durability and a high antibacterial performance.
As an example of such a wiping cloth, JP 9-19393 A discloses a high-density woven fabric made from a composite yarn consisting of synthetic microfibers and synthetic high denier fibers, which wiping cloth exhibits excellent performance in wiping away oil stains and dirt from glass lenses. However, the mere use of a composite yarn is insufficient to completely wipe away the oil stains and dust from the surface of the lenses, and spreads the oil stains and dust, resulting in a leftover residue. A wet cloth containing a cleaning liquid is also sometimes used for wiping an object. After wiping, however, the chemicals contained in the wet cloth may be left as a residue on the surface of the object, and dirt cannot be completely removed.
In addition, disinfectant liquid cleaners, and the like containing alcohols and chemicals cannot be used for particular medical devices in the medical sites because the alcohols and the chemicals will deteriorate the plastic cases, touch panels, operation screens, and the like of the devices.
It could therefore be helpful to provide a wiping cloth for removing microbes, which is capable of picking up dirt from the wiped surface of an object and trapping the dirt in the cloth to ensure retention of the trapped dirt.

SUMMARY

We thus provide:
(1) A wiping cloth for removing microbes, the wiping cloth made of a fabric comprising 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm³/g or more.
(2) The wiping cloth for removing microbes according to the above (1), wherein the single fiber fineness of the synthetic microfibers is 0.1 dtex or less.
(3) The wiping cloth for removing microbes according to the above (1) or (2), wherein the fabric comprises high shrinkage fibers.
(4) The wiping cloth for removing microbes according to any of the above (1) to (3), wherein at least some of the fibers in the fabric are false-twisted.
(5) The wiping cloth for removing microbes according to any of the above (1) to (4), wherein the fabric is treated by water jet punching.
(6) The wiping cloth for removing microbes according to any of the above (1) and (3) to (5), made of a fabric made from a composite yarn consisting of 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and 50 to 20% by weight of synthetic high denier fibers with a single fiber fineness of 1 dtex or more.
(7) The wiping cloth for removing microbes according to the above (6), wherein the single fiber fineness of the synthetic microfibers is 0.1 dtex or less.
(8) The wiping cloth for removing microbes according to any of the above (1) to (7), which has an ATP level of 100 RLU or less, the ATP level serving as an indicator of the amount of dirt in accordance with the abundance of organisms.
(9) A method of removing microbes, the method comprising wiping with the wiping cloth for removing microbes according to any of the above (1) to (8) that is damped with water.
The wiping cloth comprises 50 to 80% by weight of synthetic microfibers with a single fiber fineness of 0.1 dtex or less, and the synthetic microfibers are capable of picking up dirt from the wiped surface of an object and trapping the dirt. The wiping cloth also has a fabric structure having a bulk of 2.0 cm³/g or more and a large number of spaces communicating with each other, and the structure ensures that the dirt is trapped in the fabric and retention of the trapped dirt and does not allow the dirt to disperse out of the fabric.

DETAILED DESCRIPTION

Examples of our wiping cloth will be described below.

(1) Synthetic Microfibers and Bulk Volume

The wiping cloth is made of a fabric comprising 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm³/g or more. The single fiber fineness of the synthetic microfibers is below 1.0 dtex, preferably 0.1 dtex or less, more preferably 0.01 to 0.08 dtex, further more preferably 0.05 to 0.06 dtex. The amount of the synthetic microfibers of below 1.0 dtex contained in the fabric is preferably 50 to 80% by weight, more preferably 60 to 70% by weight, to achieve adequate bulkiness, texture, and wiping performance of the fabric. The bulk of the fabric is preferably 2.0 cm³/g or more to efficiently trap dirt into the fabric. The bulk of the fabric is preferably 10 cm³/g or less to ensure retention of the trapped dirt in the fabric.

(2) High Shrinkage Fibers

The fabric preferably comprises high shrinkage fibers with a single fiber fineness of 1 dtex or more. The high shrinkage fibers of 1 dtex or more imparts bulk to the fabric. The fineness of the high shrinkage fibers is more preferably 2 to 4 dtex. The shrinkage (%) of the high shrinkage fibers of 1 dtex or more is not particularly limited as long as the shrinkage is high. Preferably, the shrinkage under heat of the high shrinkage fibers is higher than that of the synthetic microfibers. For example, when the shrinkage in boiling water of the synthetic microfibers is about 4 to 8%, the shrinkage in boiling water of the high shrinkage fibers of 1 dtex or more is preferably about 10 to 25%. That is, the shrinkage in boiling water of the high shrinkage fibers of 1 dtex or more is preferably higher than that of the synthetic microfibers. When the shrinkages of the two types of fibers are as described above, stronger shrinkage occurs under heat treatment in the high shrinkage fibers of 1 dtex or more than in the synthetic microfibers and, as a result of this shrinkage behavior, the filament orientation in the synthetic microfibers is disturbed and the bulk of the surface of the fabric is increased.

(3) False Twisting

The synthetic microfibers are preferably crimped by false twisting. The crimping by false twisting disturbs the filament orientation and enhances the wiping performance and dust-trapping performance of the surface of the fabric. False twisting can be performed by usual woolly texturing.

(4) Knitted and Woven Fabrics

The wiping cloth may be a woven fabric, a knitted fabric, or a nonwoven fabric, but is not limited thereto. The wiping cloth may be a composite fabric of a woven or knitted fabric and a nonwoven fabric. Preferred is a knitted fabric, because by disturbing the orientation of the constituent filaments, a knitted fabric is made into a wiping cloth that can be used without any limitation of the wiping direction. Such disturbance of the filament orientation is achieved by, for example, water jet punching, and as a result of this treatment, the synthetic microfibers on the surface are partially entangled with the synthetic high denier fibers and the directions of the loops are randomized.

(5) Water Jet Punching

The fabric is preferably subjected to water jet punching to create spaces in the fabric. The water jet punching is performed by ejecting filter-purified water from small nozzles at a given pressure to the surface of the fabric. The water pressure is preferably 30 to 120 kgf/cm², more preferably 50 to 80 kgf/cm². Water jet punching at a water pressure of below 30 kgf/cm²is not significantly effective, resulting in lack of shape stability and insufficient entanglement of the fibers. In contrast, water jet punching at a water pressure of above 120 kgf/cm²may cause breakage of the filaments in the synthetic microfibers, which breakage may cause lint.

(6) Synthetic Microfibers and Synthetic High Denier Fibers

To achieve adequate bulk and an adequate wiping performance of the fabric, the fabric is preferably made from a composite yarn comprising synthetic microfibers with a single fiber fineness of 0.1 dtex or less preferably in an amount of 50 to 80% by weight, more preferably in an amount of 60 to 70% by weight, and synthetic high denier fibers with a single fiber fineness of 1 dtex or more in an amount equal to the remaining percentage. The single fiber fineness of the synthetic high denier fibers is 1 dtex or more, preferably 2 to 4 dtex. The fabric should not comprise synthetic high denier fibers with single fiber fineness of above 4 dtex, which fibers may deteriorate the texture and wiping performance of the fabric. The above-described synthetic high denier fibers with a single fiber fineness of 1 dtex or more serves as high shrinkage fibers and are thus preferably not subjected to false twisting.

(7) ATP Levels

The water jet-punched fabric is dried at 100° C. or higher for evaporation of the moisture and hydrophilic components. The fabric is then cut into an appropriate size as a product, washed with ultrapure water (or a liquid having an equivalent function), dried, and packaged in a clean room to produce a clean product (a wiping cloth for removing microbes). The term “clean product” herein refers to a product on the surface of which the total amount of ATP (adenosine triphosphate) and AMP (adenosine monophosphate) present is at a certain level or lower. The ATP levels will be further described below.
ATP is an essential energy substance for every organism. ATP is contained in dirt derived from microorganisms or organisms and, hence, the measurement of the amounts of ATP and AMP, a product of ATP decomposition, contained in the microbe-removing wiping cloth objectively confirms the contamination by microbes. The measurement is performed using, for example, a luminescence reagent containing firefly luciferase, luciferin, and pyruvate phosphate dikinase (PPDK). Firefly luciferase produces light in the presence of ATP and luciferin. This reaction also produces AMP. The AMP is converted into ATP by PPDK and again subjected to the reaction with the luminescent reagent. In this manner, the intensity of the light corresponding to the total amount of ATP is obtained. The intensity of the light is then measured with a particular measuring device to determine the degree of dirt.

(8) Method of Determining Degree of Dirt

An exemplary method of determining the degree of dirt will be specifically described below.

Object Subjected to Measurement

The object to be subjected to the measurement is a SUS304 flat board. The surface of the board is cleaned by wiping with purified water before the measurement.

Spraying of Dirt Substance

On the surface of the board, a 5% by weight aqueous solution of yeast extract is sprayed at 0.1 g/0.05 m²with an atomizer.

Wiping Off of Dirt Substance

A cotton swab is wetted with 0.05 g of purified water, and the surface of the board on which the dirt substance has been sprayed is wiped with the cotton swab under a load of 1.2 kg by sliding the cotton swab back and forth across a distance of 40 cm ten times so that the aqueous solution of yeast extract is removed with the cotton swab.

Measurement of Intensity of Light

The cotton swab used to wiped off the aqueous solution of yeast extract is immersed in an extraction reagent (containing a surfactant (benzalkonium chloride)) to extract ATP. The extracted ATP is reacted with a luminescent reagent containing firefly luciferase, luciferin and PPDK to produce light. The intensity of the light is measured with a luminescence meter (for example, “Lumitester PD-20” (trade name) produced by Kikkoman Biochemifa Company). The value of the ATP level of the dirt substance when measured with the luminescence meter is expressed as a relative light unit (RLU) and will be within the range of 10000±500 (RLU).

Clean Product

In the field of medical devices, which is considered to have the strictest demands for cleanliness, the relative light unit of the amount of ATP on an endoscope is often required to be 100 RLU or less.

(9) Applications of Wiping Cloth for Removing Microbes

The wiping cloth is capable of picking up and trapping dirt thereinto, as if it scrapes the dirt, and does not leave a streaky residue. Due to these advantages, the wiping cloth is applicable to various devices of which the surfaces require high cleanliness. For such applications, the wiping cloth is wetted with water to exhibit an improved wiping performance. The wiping cloth does not require chemicals such as alcohols and disinfectant liquid cleaners and, hence, does not deteriorate the wiped surface of an object and does not affect the appearance of the surfaces of devices. The wiping cloth is, therefore, applicable to maintenance of various types of medical devices that require extreme cleanliness (for example, infant incubators, PET, PET/CT, and the like).

(10) Thickness of Wiping Cloth for Removing Microbes

The thickness of the wiping cloth for removing microbes has a large influence on the dirt-wiping performance and the handling property, and is thus preferably 100 μm to 2 mm. The wiping cloth with a thickness of 500 μm to 1 mm exhibits more preferred wiping performance and handling property. However, the wiping cloth with a thickness of below 100 μm cannot sufficiently pick up dirt and thus is not preferred. The wiping cloth with a thickness of above 2 mm exhibits poor handling property and requires more production cost and thus is also not preferred.

EXAMPLES

Our wiping cloths will be specifically described with reference to Examples, but are not limited to thereto. Various alterations and modifications are possible without departing from the technical scope of this disclosure.

Example 1

The synthetic microfibers used were “UTS” of 66 dtex and 9 filaments produced by Toray Industries, Inc. (an islands-in-the-sea type composite polyester ultrafine micro yarn splittable with a solvent (alkaline hot water-soluble polyester fibers composed of polyethylene terephthalate as the island component and a copolymer of polyester with terephthalic acid and 5-sodium sulfoisophthalic acid (acid units) as the sea component, with the ratio of the island and sea components of 20/80, and a shrinkage in boiling water of 9%)). The synthetic high denier fibers used were a polyester yarn of 33 dtex and 6 filaments (produced by Toray Industries, Inc., a high shrinkage yarn with a shrinkage in boiling water of 21%). The synthetic microfibers were false-twisted, arranged in parallel with the synthetic high denier fibers, and air-entangled to produce a composite yarn. The yarn was interlock knitted with a circular knitting machine (32 G, 97 cm) to produce a greige fabric. The greige fabric was heat treated at 130° C. for 20 minutes and then treated at 80° C. for 30 minutes in the presence of 1% sodium hydroxide to completely remove the sea component. The fineness of the microfibers after removal of the sea component was 0.08 dtex. The fabric was then water jet-punched with water ejected to the surface at a pressure of 100 kg/cm². The fabric was heat set at 135° C. so that the wale and course counts were 60/2.54 cm. The fabric was washed with ultrapure water and dried at 80° C. The obtained knitted fabric contained 65% by weight of the synthetic microfibers and was highly dense with the number of the constituent filaments, most of which were the synthetic microfibers, being about 35000/2.54 cm both in the wale and course directions. The single fiber fineness of the synthetic microfibers in the knitted fabric was 0.08 dtex, and the single fiber fineness of the synthetic high denier fibers in the knitted fabric was 2.4 dtex.
The bulk of the high-density knitted fabric was 2.6 cm³/g, and the thickness was 0.52 mm.
The bulk and thickness of the high-density knitted fabrics herein were determined as follows, with reference to JIS L1018 (Test methods for knitted fabrics).

Measurement of Thickness

A square sample of 20 cm in width and length was cut out from a knitted fabric and the thickness was measured with a thickness gauge under a predetermined pressure applied with a presser foot. The diameter of the presser foot was 10 cm². The pressure was 7 gf/cm². Ten seconds after applying the pressure, the dial gauge (peacock dial gauge) was read to determine the thickness t (mm) of the knitted fabric.

Measurement of Bulk

The weight (g/m²) of the square sample of 20 cm in width and length was measured, and the bulk (cm³/g) was calculated from the above thickness t (mm) and the weight W (g/m²) based on the following formula:
Bulk (cm³/g)=(t/W)×1000.

Measurement of ATP Levels

(1) Before the First Wiping

In the same manner as described above, on the surface of a SUS304 flat board, a 5% by weight aqueous solution of yeast extract was sprayed, the aqueous solution of yeast extract was wiped off with a cotton swab, and the ATP level of the cotton swab was measured with a luminescence meter as described above to determine the ATP level before the first wiping.

(2) After the First Wiping

After the above measurement of the ATP level on the surface of the SUS304 board as described above, the following procedures were performed. The high-density knitted fabric (the wiping cloth for removing microbes) produced as described above was wrapped around a rectangular pad of 6 cm×4 cm to produce a testing wiping cloth. The testing wiping cloth with a 1.2-kg metal weight on it was placed on the surface of the SUS304 board on which the 5% by weight aqueous solution of yeast extract was sprayed (a different part of the surface of the SUS304 board from the part from which the solution was wiped off with the cotton swab described above), and the wiping cloth was then slid for a distance of 10 cm to wipe off the aqueous solution of yeast extract. The same part of the surface of the SUS304 board from which the aqueous solution of yeast extract was wiped off with the testing wiping cloth was wiped with a cotton swab under a load of 1.2 kg by sliding the cotton swab back and forth across a distance of 40 cm ten times. The ATP level of the cotton swab was measured with a luminescence meter as described above to determine the ATP level after the first wiping.
(3) Testing Wiping Cloth (Wiping Cloth for Removing Microbes Wrapped Around a Rectangular Pad of 6 cm×4 cm)
The surface of the testing wiping cloth before used for wiping the surface of the SUS304 board was wiped with a cotton swab under a load of 1.2 kg by sliding the cotton swab back and forth across a distance of 40 cm ten times. The ATP level of the cotton swab was measured with a luminescence meter as described above to determine the ATP level of the testing wiping cloth before wiping. The testing wiping cloth was then used to wipe the surface of the SUS304 board on which the 5% by weight aqueous solution of yeast extract was sprayed as described above, and the ATP level of the testing wiping cloth was measured in the same manner as described above to determine the ATP level of the testing wiping cloth after the first wiping.
In the same manner as described above, the ATP levels on the surface of the SUS304 board were measured with a luminescence meter before and after the second to the fifth wiping, and the ATP levels of the testing wiping cloth were measured with a luminescence meter after the second to the fifth wiping.
Table 1 shows the relative light units (RLUs) indicating the ATP levels when dry wiping was performed with the testing wiping cloth in a manner that the direction of wiping coincided with the wale direction. Table 2 shows the RLUs indicating the ATP levels when dry wiping was performed with the testing wiping cloth in a manner that the direction of wiping was perpendicular to the wale direction. Table 3 shows the RLUs indicating the ATP levels when the testing wiping cloth was damped with purified water at 0.1 g/24 cm³and then damp wiping was performed with the wiping cloth in a manner that the direction of wiping coincided with the wale direction. Table 4 shows the RLUs indicating the ATP levels when the testing wiping cloth was damped with purified water at 0.1 g/24 cm³and then damp wiping was performed with the wiping cloth in a manner that the direction of wiping was perpendicular to the wale direction. In Tables 1 to 12, the term “degree of cleaning” means the remainder after subtraction of the ATP level after wiping from the ATP level before wiping, and the term “percentage degree of cleaning” means the ratio calculated by subtracting the ATP level after wiping from the ATP level before wiping and dividing the remainder by the ATP level before wiping.

	TABLE 1

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 35

1st	10034	782	9252	92.2	After wiping: 49
2nd	10493	612	9881	94.2	After wiping: 100
3rd	9681	736	8945	92.4	After wiping: 83
4th	10367	458	9909	95.6	After wiping: 128
5th	9725	455	9270	95.3	After wiping: 138

	TABLE 2

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 28

1st	10156	539	9617	94.7	After wiping: 112
2nd	10391	562	9829	94.6	After wiping: 149
3rd	10417	438	9979	95.8	After wiping: 78
4th	10021	763	9258	92.4	After wiping: 109
5th	9968	657	9311	93.4	After wiping: 152

	TABLE 3

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 40

1st	10147	82	10065	99.2	After wiping: 75
2nd	9516	98	9418	99.0	After wiping: 28
3rd	9837	77	9760	99.2	After wiping: 41
4th	10439	58	10381	99.4	After wiping: 60
5th	9642	38	9604	99.6	After wiping: 59

	TABLE 4

	SUS304 board surface

1st	10492	64	10428	99.4	After wiping: 40
2nd	10382	72	10310	99.3	After wiping: 101
3rd	9688	85	9603	99.1	After wiping: 39
4th	10256	43	10213	99.6	After wiping: 78
5th	10437	29	10408	99.7	After wiping: 62

As is apparent from Tables 1 to 4, the water jet-punched wiping cloth showed no difference in the ATP levels on the surface of the SUS304 board between the cases of wiping in the wale direction and wiping perpendicular to the wale direction both in the damp wiping and the dry wiping (comparison of Tables 1 and 2, and comparison of Tables 3 and 4). The ATP levels on the surface of the SUS304 board were reduced to a greater extent in the damp wiping (Tables 3 and 4) than in the dry wiping (Tables 1 and 2). The increase in the ATP levels on the testing wiping cloth was lower in the damp wiping than in the dry wiping, even when the wiping was repeated.

Example 2

The synthetic microfibers used were “PICEME” of 56 dtex and 18 filaments produced by Toray Industries, Inc. (a splitting type yarn composed of a polyamide star-shaped core being surrounded by triangular polyester fibers between the branches of the star, with a shrinkage in boiling water of 12%). The synthetic high denier fibers used were a polyester yarn of 33 dtex and 6 filaments (produced by Toray Industries, Inc., a high shrinkage yarn with a shrinkage in boiling water of 21%). The synthetic microfibers were false-twisted, arranged in parallel with the synthetic high denier fibers, and air-entangled to produce a composite yarn. The yarn was interlock knitted with a circular knitting machine (32 G, 96.5 cm) to produce a greige fabric. The greige fabric was heat treated at 80° C. for 60 minutes in the presence of 2% NaOH in a jet dyeing machine to split the fibers. Splitting the synthetic microfibers resulted in polyester yarns of 0.27 dtex and nylon yarns of 0.93 dtex. The fineness of the synthetic high denier fibers was 30 dtex (6 filaments). The obtained fabric was dried at 120° C. for 3 minutes, and finished by heat setting at 160° C. for 30 seconds to produce a finished knitted fabric with 151 wales per 2.54 cm and 190 courses per 2.54 cm. The knitted fabric contained 63.5% by weight of the synthetic microfibers. The bulk of the high-density knitted fabric was 2.6 cm³/g, and the thickness was 0.52 mm.
In the same manner as described above, the ATP levels on the surface of the SUS304 board were measured with a luminescence meter before and after the first to the fifth wiping, and the ATP levels of the testing wiping cloth were measured with a luminescence meter before wiping and after the first to the fifth wiping.
Table 5 shows the relative light units (RLUs) indicating the ATP levels when dry wiping was performed with the testing wiping cloth in a manner that the direction of wiping coincided with the wale direction. Table 6 shows the RLUs indicating the ATP levels when dry wiping was performed with the testing wiping cloth in a manner that the direction of wiping was perpendicular to the wale direction. Table 7 shows the RLUs indicating the ATP levels when the testing wiping cloth was damped with purified water at 0.1 g/24 cm³and then damp wiping was performed with the wiping cloth in a manner that the direction of wiping coincided with the wale direction. Table 8 shows the RLUs indicating the ATP levels when the testing wiping cloth was damped with purified water at 0.1 g/24 cm³and then damp wiping was performed with the wiping cloth in a manner that the direction of wiping was perpendicular to the wale direction.

	TABLE 5

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 38

1st	10162	754	9408	92.6	After wiping: 106
2nd	10337	1132	9205	89.0	After wiping: 92
3rd	10006	987	9039	90.3	After wiping: 69
4th	9731	815	8916	91.6	After wiping: 97
5th	10418	1023	9395	90.2	After wiping: 134

	TABLE 6

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 42

1st	9570	529	9041	94.5	After wiping: 142
2nd	10472	467	10005	95.5	After wiping: 84
3rd	10221	352	9869	96.6	After wiping: 79
4th	9856	618	9238	93.7	After wiping: 104
5th	9735	438	9297	95.5	After wiping: 116

	TABLE 7

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 22

1st	9501	135	9366	98.6	After wiping: 36
2nd	9516	149	9367	98.4	After wiping: 48
3rd	9837	120	9717	98.8	After wiping: 61
4th	10439	125	10314	98.8	After wiping: 59
5th	9642	172	9470	98.2	After wiping: 77

	TABLE 8

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 31

1st	9739	108	9631	98.9	After wiping: 98
2nd	10452	89	10363	99.1	After wiping: 47
3rd	10337	112	10225	98.9	After wiping: 58
4th	10272	72	10200	99.3	After wiping: 71
5th	10319	58	10261	99.4	After wiping: 63

As is apparent from the results for the non-water jet-punched wiping cloth in Tables 5 to 8, wiping perpendicular to the wale direction resulted in larger decreases in the ATP levels on the surface of the SUS304 board than wiping in the wale direction (comparison of Tables 5 and 6, and comparison of Tables 7 and 8). The ATP levels on the surface of the SUS304 board were reduced to a greater extent in the damp wiping (Tables 7 and 8) than in the dry wiping (Tables 5 and 6). The increase in the ATP levels on the testing wiping cloth was lower in the damp wiping than in the dry wiping, even when the wiping was repeated.

Comparative Example 1

The synthetic fibers used were a polyester false-twisted yarn of 82.5 dtex and 72 filaments. The yarn was interlock knitted with a circular knitting machine (28 G) to produce a greige fabric. The greige fabric was washed with hot water at 60° C. for 10 minutes in a jet dyeing machine and then washed with water at room temperature. The greige fabric was scoured with caustic soda and a low foaming scouring agent containing a polyoxyalkylether compound as its main component to remove the oil adhering to the greige fabric. The surface of the polyester fibers was slightly melted to impart a hydrophilic nature to the polyester fibers. The fabric was then washed twice with hot water at 60° C. for 10 minutes so that the caustic soda was removed as much as possible. The fabric was dried and heat-set at 160° C. The fabric was washed with ultrapure water and dried at 80° C. The single fiber fineness of the synthetic fibers in the knitted fabric was 2.1 dtex.
The bulk of the high-density knitted fabric was 5.2 cm³/g, and the thickness was 0.74 mm.
In the same manner as described above, the ATP levels on the surface of the SUS304 board were measured with a luminescence meter before and after the first to the fifth wiping, and the ATP levels of the testing wiping cloth were measured with a luminescence meter before wiping and after the first to the fifth wiping.
Table 9 shows the relative light units (RLUs) indicating the ATP levels when dry wiping was performed with the testing wiping cloth in a manner that the direction of wiping coincided with the wale direction. Table 10 shows the RLUs indicating the ATP levels when dry wiping was performed with the testing wiping cloth in a manner that the direction of wiping was perpendicular to the wale direction. Table 11 shows the RLUs indicating the ATP levels when the testing wiping cloth was damped with purified water at 0.1 g/24 cm³and then damp wiping was performed with the wiping cloth in a manner that the direction of wiping coincided with the wale direction. Table 12 shows the RLUs indicating the ATP levels when the testing wiping cloth was wetted with purified water at 0.1 g/24 cm³and then damp wiping was performed with the wiping cloth in a manner that the direction of wiping was perpendicular to the wale direction.

	TABLE 9

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 56

1st	10345	4327	6018	58.2	After wiping: 197
2nd	10274	5187	5087	49.5	After wiping: 731
3rd	10105	8026	2079	20.6	After wiping: 804
4th	10378	7237	3141	30.3	After wiping: 1003
5th	10467	5895	4542	43.7	After wiping: 977

	TABLE 10

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 67

1st	10042	6701	3341	33.3	After wiping: 623
2nd	9898	4368	5530	55.9	After wiping: 551
3rd	9872	4629	5043	52.1	After wiping: 670
4th	10430	6552	3878	37.2	After wiping: 785
5th	10216	8798	1418	13.9	After wiping: 843

	TABLE 11

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 37

1st	9827	291	9536	97.0	After wiping: 4685
2nd	10318	346	9972	96.6	After wiping: 7285
3rd	10492	953	9539	90.9	After wiping: 13573
4th	9684	684	9000	92.9	After wiping: 18076
5th	10251	773	9478	92.5	After wiping: 24310

	TABLE 12

	SUS304 board surface

			Percentage	Testing wiping cloth
Before	After	Degree of	degree of	ATP level
wiping	wiping	cleaning	cleaning (%)	before wiping: 44

1st	10356	456	9900	95.6	After wiping: 7561
2nd	10446	574	9872	94.5	After wiping: 8956
3rd	10378	721	9657	93.1	After wiping: 10072
4th	10210	864	9346	91.5	After wiping: 15737
5th	9619	690	8929	92.8	After wiping: 19359

As is apparent from Tables 9 to 12, the ATP levels of the surface of the SUS304 board were reduced to a much greater extent in the damp wiping (Tables 11 and 12) than in the dry wiping (Tables 9 and 10). However, even when the damp wiping was performed, the ATP levels after the wiping was about 300 RLU or more in Comparative Example 1. Such a wiping cloth with large-diameter fibers as in Comparative Example 1 is not expected to exert our effect of “trapping dirt in the entanglement of synthetic microfibers and synthetic high denier fibers and retaining the dirt in the fabric”, and has thus poor wiping performance.
The above results revealed that an ATP level of about 100 RLU or less is achieved by damp wiping with a water jet-punched wiping cloth comprising synthetic microfibers as its main constituent and having a high bulk, or by damp wiping with a non-water jet-punched wiping cloth comprising synthetic microfibers as its main constituents and having a high bulk in a wiping manner that the direction of wiping is perpendicular to the wale direction.

INDUSTRIAL APPLICABILITY

Our wiping cloth is particularly suitable for removing microbes from medical devices.

Claims

1.-9. (canceled)

10. A wiping cloth for removing microbes, the wiping cloth made of a fabric comprising 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm³/g or more.

11. The wiping cloth according to claim 10, wherein the single fiber fineness of the synthetic microfibers is 0.1 dtex or less.

12. The wiping cloth according to claim 10, wherein the fabric comprises high shrinkage fibers.

13. The wiping cloth according to claim 10, wherein at least some of the fibers in the fabric are false-twisted.

14. The wiping cloth according to claim 10, wherein the fabric is treated by water jet punching.

15. The wiping cloth according to claim 10, made of a fabric made from a composite yarn consisting of 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and 50 to 20% by weight of synthetic high denier fibers with a single fiber fineness of 1 dtex or more.

16. The wiping cloth according to claim 15, wherein the single fiber fineness of the synthetic microfibers is 0.1 dtex or less.

17. The wiping cloth according to claim 10, which has an ATP level of 100 RLU or less, the ATP level serving as an indicator of an amount of dirt in accordance with the abundance of organisms.

18. A method of removing microbes comprising wiping with the wiping cloth according to claim 10 that is wetted with water.

19. The wiping cloth according to claim 11, wherein the fabric comprises high shrinkage fibers.

20. The wiping cloth according to claim 11, wherein at least some of the fibers in the fabric are false-twisted.

21. The wiping cloth according to claim 11, wherein the fabric is treated by water jet punching.

22. The wiping cloth according to claim 11, which has an ATP level of 100 RLU or less, the ATP level serving as an indicator of an amount of dirt in accordance with the abundance of organisms.

23. A method of removing microbes comprising wiping with the wiping cloth according to claim 11 that is wetted with water.