KR100441928B1 - Nonwoven Fabrics for Wiping Applications - Google Patents

Abstract

The present invention relates to a method of using a nonwoven fabric for wiping in a cleanroom that has been considered not optimal until now, and a nonwoven suitable for use in the cleanroom.

Description

Nonwoven Fabrics for Wiping Applications

Certain types of fabrics are used to clean surfaces. This can range from just wiping off the liquid from the kitchen counter at home to wiping the surface in a clean room, where it is important that there are preferably no particles or only very small amounts of particles left on the wiped surface. .

It has been thought that the best fabrics for important cleanrooms are knitted or unsealed knits. These fabrics are characterized by being mildly absorbent and they have been considered "clean" due to the low content of leaving particles. Leaving particles refer to particles that are already present and are being removed from the fabric, as well as newly generated particles that are formed by stressing the actual wiping fabric. These presumably superior fabrics exhibited desirable properties based on tests on the number of absorbent and leaving particles. Non-woven fabrics (such as Sontara®, a registered trademark of EI du Pont de Nemours and Company (DuPont)) are used for some cleanrooms, but It was not considered a good candidate for particularly important cleanroom applications. This was because these nonwovens were considered relatively "dirty" compared to the washed knit fabrics based on these static tests, rather than testing their actual performance during wiping. Such nonwovens have been used in cleanrooms rated at Class 100 or higher in accordance with US Federal Standard Act 209E (September 11, 1992), but typically they are rated at grade 10 or below (ie, cleaner grade). It is not fully accepted as suitable for critical clean rooms. US Federal Standard Act indicates the maximum number of suspended particulates in a given size. For example, class 100 has a maximum of 100 particles per about 0.028 cm ³ (1 ft ³ ) at 0.5 micrometer size, and class 10 has a maximum of 10 particles per 0.028 cm ³ (1 ft ³ ) at the same size. Have However, they would be preferable to use such nonwovens given their very low prices in contrast to knitted fabrics.

DuPont has been working to develop inexpensive nonwovens, particularly for cleanroom wiping. Fabrics such as Sontara® are commonly prepared in entanglement as disclosed in US Pat. No. 3,485,706 (Evans), which is incorporated herein by reference. It has been found that entangled fabrics made from 100% polyester are very hydrophobic and therefore not suitable for critical clean room applications. The hydrophilicity can be imparted to the fabric by being laundered and the surfactant contained in the fabric, but the entangled fabric typically does not have sufficient durability to withstand such a wash. Washing will cause the fabric to become lint-free and tangle loose. When a binder was added to the entangled fabric to increase durability, the fabric was not sufficiently hydrophilic for wiping.

Summary of the Invention

The present invention relates to a wiping material, characterized in that it comprises a polyester nonwoven fabric adapted for use in a clean room laundered and grade 10 or more cleanly graded clean room. The invention also relates to a method of using a nonwoven to clean a grade 10 or cleaner clean graded clean room.

The present invention relates to a fabric for wiping off liquids and / or particles from a surface.

Fabrics were evaluated using newly developed dynamic tests related to actual wiping operations, finally indicating that certain nonwovens based on, for example, Sontara® are equal to or better than the performance of the knitted fabric. Found. In addition, it has finally been discovered that clean room washing of certain types of Sontara® fabrics confers surprisingly excellent wiping properties.

There are at least three factors that are important for removing liquids from critical surfaces using wipers, whether deliberately adding liquid to the surface for cleaning purposes, or simply present by spilling liquid. The first is the dynamic efficiency with which the wiper can absorb liquids. The second is the number of particles present in the spilled liquid (or on the surface to be wiped) and the extent to which these particles are removed during the wiping process. Third is a very realistic concern with the particles and fibers that the wiper itself may leave on the surface to be cleaned.

Since residual contamination from spilled liquid is usually suspended in the liquid remaining on the wiped surface, a cleanroom wiper made of a fabric that is highly capable of "drying the surface dry" will finally clean the wiped surface than otherwise. Found. Wipe-dry is not only a desirable property for household cleanroom wiping materials, but is also considered an important property for wiping out spilled liquids of dirty liquids and further removing particles from the surface.

In selecting the wiping material to remove the liquid from the surface, we conclude that the inherent cleanliness of the wiping material (the characteristics based on the particles already present on the wiper) is less important than the ability of the same wiping material to dry clean the surface. Got off.

<General test method>

There are many test methods for evaluating fabrics for use as cleanroom wiping materials. Some methods address the functionality of the wiping material in terms of quantifying their absorbency, specifically the rate and capacity at which the wiper absorbs the liquid. Other tests relate to the cleanliness of the wiper and, in particular, to determine the number of particles or fibers that may be present or generated from the wiper in response to applied stress.

Some of the most commonly used tests to quantify the absorbency of wiping materials are the Recommended Practice of the Institute of Environmental Sciences (Mount Prospect East Northwest Highway 940, 60056, Illinois, USA). 004.2 ("Evaluating Wiping Materials Used in Cleanrooms and Other Controlled Environments," IES-RP-CC004.2 (1992)). This test is used in the present invention to quantify the intrinsic absorption capacity of the evaluated wiping material.

However, other methods also exist as follows.

INDA standard test 10.1-95 ("Measuring Absorbency Time, Absorbency Capacity, and") of the Association of the Nonwoven Fabrics Industry (INDA), Carrie Suit 125 Crested Green 1300, 27511 North Carolina, USA, which describes the basket test and wicking rate test. Wicking Rate ").

IES-RP-CC004-87-T ("Wipers Used in Clean Rooms and Controlled Environments," by the Environmental Sciences Society (Motor Prospect East Northwest Highway 940, 60056, Illinois) describing the 1/2 absorption time test. 1987)).

AATCC Method No. of the Association of Textile Chemists and Colorists, describing the droplet test. 79-1992 ["Absorbency of Bleached Textiles," AATCC Technical Manual, 68, 106 (1993)].

Miller, B. and Tyomkin, I., Textile Research Journal, 54, 708 (1984) and Painter, E. V., TAPPI, 68 (12), 54 (1984), which describe required absorbency tests (GATS).

All of these tests recognize the difference in wiping material (also called wiper) according to their ability to absorb liquids, while the tests describe the substantial static properties of the wiper. None of these deal directly or indirectly with the wiper's ability to remove liquid from the surface in a dynamic manner, i.e. under pressures and conditions similar to those present during hand-wiping.

While wiping the dead fluid by hand using the wiper, the liquid is absorbed into the fabric. At the same time, however, other forces can work against this absorption process. For example, the pressure acting during wiping may delay absorption or dehydrate liquid already absorbed from the wiper. In addition, surface tension differences can affect the liquid distribution between the wiper and the surface. All wipers cannot be "wiped and dried" even when they have not exceeded their absorbent capacity as measured from static tests such as those described above. This is especially true for articles made from hydrophobic synthetic polymers, which often leave water marks or droplets in place after wiping by hand.

In evaluating the wiping material for cleanliness in relation to the particles, the focus is generally on determining how many particles are present in or on the wiper or how many particles are released from the wiper in response to the stress applied. come. In some of the initial tests, the wiper was tested in the dry state, but the generation, collection, and calculation of particles is now allowed to run on the wiper in the wet state.

Among these most useful wet tests are the following two methods. The first is Matttina, CF and Paley, SJ, "Assessing Wiping Materials for their Potential to Contribute Particles to Clean Environments: A Novel Approach," Particles in Liquids and Gases 2: Detection Characterization and Control, KL Mittal, editor, 117- 128, Plenum Publishing Corporation, New York (1990)] is a test for the number of easy leaving particles found in a wiper. The second method is described in Mattina, CF and Paley, SJ, "Assessing Wiping Materials for their Potential to Contribute Particles to Clean Environments: Constructing the Stress Strain Curves", Journal of the IES, 34 (5), 21 (1991) and Oathout, J. Marshall and Mattina, Charles F., on each wiper as provided in "A Comparison of Commercial Cleanroom Wiping Materials for Properties Related to Functionality and to Cleanliness," Journal of the IES, 38 (1), 41 (1995). Creating characteristic curves for These methods show how particles occur in response to the application of known amounts of mechanical energy.

As described in the Environmental Sciences Society (Wipers Used in Clean Rooms and Controlled Environments, IES-RP-CC004-87-T (1987)), 940, Mount Prospect East Northwest Highway, Illinois, USA. Another test of shaking the wiper in the liquid in a biaxial shaker is also used in some cases. This is modified in Atterbury, O., Bhattacharjee, HR, Cooper, DW, Dominique, JR, Paley, SJ, Siegerman, H., "Evaluating Cleanroom Wipers to Establish Performance Benchmarks", Micro, 51, 5 (1998). And counting the particles with a scanning electron microscope after the addition of the surfactant. This simulates the stress experienced during actual use similarly to the test for the above-mentioned leaving particles, but the amount of energy imparted through such shaking is unknown.

All of these test methods are incorporated herein by reference.

<Test method of the present invention>

There are only a few ways to assess the fabric's ability to dry its surface. Macfarlane, K., "Assessing Wipe Performance," Proceedings of IDEA '98 (INDA), 12.1 (1998), describe such tests. Some aspects of the Macfarlane test were used to develop a dynamic wiping efficiency test as described below.

Mattina, CF, McBride, J., Nobile, D. and Turner, K., "The Cleanliness of Wiped Surfaces: Particles Left Behind as a Function of Wiper and Volume of Solvent Used," Proceedings, CleanRooms '96 East, 183 (1996) provides data on particles remaining on clean surfaces originating from wipers whose absorption capacities are increased differently. When a volume of liquid below its absorbing capacity is applied to the wiper, relatively few particles remain, but it is finally found that all wipers leave a large number of particles when their capacity is exceeded in the opposite situation. Surprisingly, regardless of the composition or structure, the number of particles left by the wiper becomes very similar once the absorbent capacity of the wiper is exceeded. There is a common common sense that so-called "clean" fabrics leave proportionally fewer particles than so-called "dirty" fabrics. However, it has been observed that the wiper's ability to remove liquid from the surface is very important because only an excessive number of particles remain when the liquid is left by the wiper.

A second test was developed using some factors of the method of Martina et al to determine the number of particles remaining on the surface after dynamic wiping. When particles from an external source are intentionally included in a test liquid, the test is referred to as a particle removal capability (PRA) test.

The new test method is described in detail below.

Dynamic wiping efficiency

As noted above, some improvements have been made to the McFarlane apparatus and procedures. A wiping speed of 25 cm / sec closer to the actual wiping than 50 cm / sec was used. A 50 cm stainless steel tray with an internal long axis dimension of 45 cm was used, providing a clearance of about 36 cm in front of the 1 kg sled. The width of the sled was 114 mm on the edge to accommodate a quarter of the wiping material folded from its most common size of 229 mm by 229 mm (9 inches by 9 inches).

Instead of a single conductive liquid consisting of 1 ml of water, many different volumes of liquid were used up to approximately 130% of the wiper's absorption capacity as measured by its intrinsic absorption capacity. In this way, efficiency curves can be plotted for all wipers, if desired, as a function of the volume of the conductive liquid or as a function of the absorbent capacity of the wipers.

Rather than placing the fabric and sleds directly on the liquid pool to allow time to elapse before the start of crossing, the liquid conducting liquid is placed in front of the sled passing into the pool to more closely mimic the actual spillage.

The following equipment was used.

Balance: Top-loaded, sealed, 0.01 g readout tray:

Stainless steel, internal dimensions 45 cm x 28 cm x 7 cm, large enough to contain water in which the particles were counted; See description below.

Sled: stainless steel, 1 kg, 114 mm x 114 mm bottom; The leading curve edge on the bottom of the sled forms a lip to which the quarter folded sample is attached using a spring loaded clip. Two stainless steel screws are attached to the outer edge of the sled at the leading curve edge.

Dispenser: Brinkmann Bottletop Buret, Model 25, for delivering reproducible and accurate volume of liquid.

Water: for convenience (but not required), use clean water as if the number of particles were counted; See description below.

Device: A polyester spring is attached to the sled in a stainless steel screw to form a yoke. A second polyester spring (about 1.22 m in length (about 4 ft)) is attached to the middle of the yoke. Using the spring, pull the sled by hand at a speed of about 25 cm / sec.

It should be understood that equipment equivalent to or appropriately similar to the above may be used.

The procedure was as follows.

1. Fold a single layer of wiping material (nominal 229 mm x 229 mm) in quarters and measure its dry weight, M _d, to 0.01 g.

2. Secure the 1 / 4-fold wiper to the sled so that a single convex fold line is at the leading edge.

3. Place the sled at one end of the stainless steel tray with the leading edge perpendicular to the long axis of the tray.

4. If the wiper's intrinsic absorption capacity, A _i , is not already known, use the IEST-RP-CC004.2 procedure referenced above to determine the intrinsic absorption capacity for the individual plies of material. The capacity A _ip [ml / g] per layer for each wiper is calculated from the calculated A _i and the measured mass of each wiper. This amount is necessary to know what fraction of the absorption capacity is represented by each volume of the liquid conductive liquid.

5. Using a distributor, place the desired volumetric conductivity of water, v _c, into the tray at a point about 1-2 cm in front of the leading edge of the sled.

6. Using a spring, drive the sled at a rate of approximately 25 cm / sec along the long axis of the tray, approximately 36 cm (in front of the sled, allowing room for lifting the sled and wiper without hitting the tray lip). Pass it through the water). Remove the sled and the wiper from the tray by lifting the sled smoothly and quickly with the spring.

7. Remove the folded wiper from the sled, measure the wet mass of the wiper, m _w, and measure the mass of water absorbed by the difference. Calculate the volume of water absorbed, v _s , using the density of water (0.997 g / ml at 25 ° C.). The dynamic wiping efficiency, DWE, is calculated by dividing the volume of water absorbed, v _s , by the volume of the conductive liquid, v _c , and converting it to a percentage.

DWE = 100 [(m _w -m _d ) /0.997] / v _c = 100 v _s / v _c

DWE can be expressed as the absolute volume of the conductive liquid, a function of v _{c and} a function of the conductive liquid with respect to A _i . Relative conductivity is expressed as 100 v _c / A _ip .

Particle removal ability

In order to measure the wiper's ability to remove particles from the surface, a test for dynamic wiping efficiency is combined with the specific factors of the test described by Martina et al. Above to quantify the number of particles left on the surface originating from the wiper. It was. The difference was the addition of a known number of poly (styrene) spheres to the liquid conductive solution and the use of a quarter folded sample instead of an unfolded sample. The results from this procedure are referred to as "particle removal capacity" or PRA. For all practical purposes, the test for DWE and PRA is one test conducted with or without particles added to the liquid conductive liquid.

A conductive solution of water in which poly (styrene) spheres of known dimensions and concentrations were dispersed was aspirated into a 1/4 folded wiper (attached as above to the underside of the sled and pulled across a clean stainless steel pan). After the sled and fabric were removed from the tray, the particles and liquid on the tray were dispersed in clean water and counted with a discrete particle counter. Particles remaining from the conductive liquid were expressed in terms of the volume of the liquid conductive liquid, v _c , and in terms of conductivity, expressed as a percentage of the absorbent capacity of the fabric, 100 v _c / A _ip .

A significant number of (about 10 × 10 ⁶ ) spheres were administered to the water conductive solution, after wiping and subsequent dilution, a significant number of spheres remained to distinguish them from the background coefficient of fresh water. For convenience, a spherical body of 1.59 micrometers in diameter was chosen to be safely measured in the 1.0-3.0 micrometer channel of the discrete particle counter. The spheres were deposited using a micrometer syringe and the plunger of the syringe was adjusted gradually until 10 × 10 ⁶ spheres could be reproducibly released. The work of this part was carried out on a horizontal laminar flow clean bench (Atmos Tech, Model 6302). The air produced by the workbench monitored when using a discrete particle counter (Met One, Model 227) is US Federal Standard Act 209E ("Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones," September 1992 11 Consistent with Grade 10 or cleaner requirements as defined in (i.e. 0.5 micrometers).

In addition to the above materials and equipment, the following were used.

Sphere: Poly (styrene), particle deposition standard, Duke Scientific Surf-Cal Scanner, PD 1600, 1.59 micrometers at 3 × 10 ⁸ / ml concentration.

Syringe: Hamilton, 50 microliters.

Water: Millipore consisting of reverse osmosis unit (Milli-RO 10 Plus), ordered filter and ion exchange layer (Milli-Q UF Plus), and 0.2 micrometer filter (Millipak 40) (mounted at point of use) ) system.

Particle counter: PMS microlaser particle spectrometer (μLPS) equipped with Corrosive Liquid Sampler, Model 200.

The procedure was as follows.

1. Clean the stainless steel pan and measure the background concentration of particles (1.0-3.0 micrometers) in 1000 mL volume of water therein.

2. Fold a single ply wiping material (nominal 229 mm x 229 mm) in quarters and measure its dry weight, m _d to 0.01 g.

3. Secure the 1 / 4-fold wiper to the sled so that a single convex fold line is at the leading edge.

4. Place the sled at one end of the stainless steel tray with the leading edge perpendicular to the axis of the length dimension of the tray.

5. Using a microliter syringe, deposit the conductive solution of the particles a few cm in front of the leading edge of the sled.

6. Using a distributor, place the desired volume of the conductive liquid, v _c , on top of the particles.

7. Using a syringe, pass the sled through the water approximately 36 cm along the long axis of the tray at a rate of about 25 cm / sec. Remove the sled from the tray.

8. Remove the folded wiper from the sled and measure its DWE as described above.

9. Add clean water of a known volume (200 ml to 1000 ml for convenience) to the tray, measure the concentration of particles in the range of 1.0 μm to 3.0 μm, subtract the background concentration, and measure the number of particles remaining from the conductive liquid. do.

10. Repeat for different values of v _c .

11. For each value of v _c , calculate the Particle Removal Capacity (PRA), the number of particles remaining from the conductive liquid (including some contributions from the wiper).

PRA can be expressed as the absolute volume of the conductive liquid, a function of v _{c and} a function of the conductive liquid with respect to A _i . Relative conductivity is expressed as 100v _c / A _ip .

<Example 1-9>

The following materials were carried out in a dynamic test method and the results obtained are further shown below.

Example 1 was DURX ™ 670, an entangled unpatterned nonwoven, consisting of 55% wood pulp and 45% (poly) ethylene terephthalate and having an average basis weight of 70.6 g (g / m ² ) per square meter. The material can be purchased from Berkshire Corporation (Great Barrington, Mass.).

Example 2 was MICROFIRST (TM), entangled 24 mesh patterned nonwoven, consisting of 45% wood pulp and 55% (poly) ethyleneterephthalate and having an average basis weight of 54.2 g / m ² . The material can be purchased from Berkshire.

Comparative Example 3 was a SUPERPOLX 1200 (trade name), a clean room laundry knit fabric consisting of 100% (poly) ethylene terephthalate and having an average basis weight of 154 g / m ² and no edge closure. The material can be purchased from Berkshire.

Example 4 was DyNamix ™ 4990Q, a entangled 40 mesh patterned nonwoven, consisting of 42% lyocell and 58% (poly) ethylene terephthalate and having an average basis weight of 75.2 g / m ² . The material can be purchased from Berkshire.

Example 5 was DyNamix ™ 6900Q, a cleanroom laundry entangled fabric, consisting of 100% (poly) ethylene terephthalate and having an average basis weight of 112 g / m ² . The starting nonwoven was a cleanroom washed Sontara® 8007 as shown below. The washed material DyNamix ™ 6900Q can be purchased from Berkshire.

Comparative Example 6 was TexWipe® TX309 consisting of 100% cotton and having an average basis weight of 173 g / m ² . The material can be purchased from Texwipe Company, Upper Saddle River, NJ.

Comparative Example 7 consisted of 100% (poly) ethylene terephthalate, an average basis weight of 141 g / m ^2, and edge-sealed Alpha 10 (registered trademark) TX1010, a clean room laundry knit fabric. The material can be purchased from Texwipe.

Comparative Example 8 was PROWIPE 880, a spunbond fabric, consisting of 100% (poly) propylene and having an average basis weight of 85.9 g / m ² . The material can be purchased from Berkshire.

Example 9 was DyNamix® 5900Q, a tangle fabric, consisting of 100% lyocell and having an average basis weight of 102 g / m ² . The material can be purchased from Berkshire.

With regard to clean room washing, there are various cycles used by those skilled in the art. It has finally been found that using a relatively high basis weight fabric of about 102 g / m ² can withstand a clean room wash / dry cycle. The method comprises stirring the fabric with a nonionic surfactant in hot water (min. 49 ° C. (120 ° F.)) (about 15 L / kg water (about 1.8 gallons / lb. Of water)). The warm water was purified by reverse osmosis treatment and the water conductivity was 4-6 μΩ / cm. The fabric was rinsed with deionized water (about 10 liters of water / kg of fabric (about 1.2 gallons per pound of water). Deionized water had a resistance of about 18 × 10 ⁶ Ω / cm. Both types of water were filtered to 0.2 micron. The total wash time was limited to a maximum of about 40 minutes.

Absorption capacity and leaving particles were measured for each Example using the Po test described in IEST-RP-CC0004.2. The results are shown in the table below. It is further noted that the following results are for particles in the range of 1 to 3 microns. Absorption capacity is expressed in ml / g and leaving particles are expressed in 10 ⁶ / m ² .

Example Basis weight (g / m ² ) Absorption Capacity (ml / g) Desorbable Particles (10 ⁶ / m ² ) One 70.6 4.36 1.53 2 54.2 5.26 1.13 3 154 3.13 1.00 4 75.2 5.42 0.341 5 112 3.89 0.830 6 173 1.48 24.8 7 141 2.58 0.663 8 85.9 5.20 1.89 9 102 6.48 2.84

Samples were tested for DWE using the method described above. Most wipers were challenged for volumes calculated to exceed 2.00, 5.00, 10.0, 15.0, 20.0 and 30.0 ml, as well as sufficient (approximately 130%) the absorption capacity of each wiper. For convenience, a conductive volume of only 10 microliters (ml) and an absorption capacity of approximately 130% were recorded for this portion of the sample. The conduction volume was converted to the capacity percentage by dividing by the absorbent capacity of the individual layers. The actual amount of liquid absorbed for each sample is shown and expressed as a percentage of the conductive volume. Tables 2 and 3 below show data for each 10 milliliters (ml) and approximately 130% absorption capacity.

Example Capacity (ml / ply) Capacity for 10 ml (%) Absorbed liquid Ml % One 15.6 64.1 9.41 94.1 2 14.4 69.4 8.96 89.6 3 23.5 42.6 9.89 98.9 4 21.3 46.9 9.18 91.8 5 22.4 44.6 9.84 98.4 6 12.3 81.3 8.38 83.8 7 16.3 61.3 8.40 84.0 8 23.4 42.7 4.35 43.5 9 34.8 28.7 9.90 99.0

Example 5-ply capacity, A _ip (ml / ply) Liquid conductivity Absorbed liquid Ml % Ml % One 15.6 20.0 128 15.6 78.0 2 14.4 20.0 138 15.7 78.5 3 23.5 30.0 128 25.4 84.7 4 21.3 27.0 128 22.7 84.0 5 22.4 29.0 129 20.3 70.0 6 12.3 16.0 130 11.3 70.6 7 16.3 21.0 129 16.8 80.0 8 23.4 30.0 128 7.70 25.7 9 34.8 45.0 129 35.7 79.3

Samples were tested for PRA using the method described above. The wiper challenged the wiper for the same set of volumes as described in the test for DWE, except that 10 × 10 ⁶ poly (styrene) spheres were administered to each conductive volume. The results for 10 mL of conductive volumetric liquid and an absorption capacity of approximately 130% are shown in Table 4 as the number of particles remaining. Particle removal efficiency (PRE) is expressed by expressing the same data as a percentage of particles removed. These redisplayed data are shown in Table 5.

2 ml 5 ml 10 ml 15 ml 20 ml 30 ml 130% capacity One 3.2 25 41 43 200 - 200 2 4.5 8.9 78 98 170 - 170 3 51 59 73 92 98 340 340 4 5.7 5.7 8.6 50 53 - 103 5 5.7 11 11 19 22 - 315 6 18 16 56 - - - 759 7 140 160 210 180 - - 333 8 280 460 620 740 2800 3100 3100 9 0.6 - 3.9 - 11 7.8 180

2 ml 5 ml 10 ml 15 ml 20 ml 30 ml 130% capacity One 99.97 99.75 99.59 99.57 98.00 - 98.00 2 99.96 99.91 99.22 99.02 98.30 - 98.30 3 99.49 99.41 99.27 99.08 99.02 96.60 96.60 4 99.94 99.94 99.91 99.50 99.47 - 98.97 5 99.94 99.89 99.89 99.81 99.78 - 96.85 6 99.82 99.84 99.43 - - - 92.41 7 98.60 98.60 97.90 98.17 - - 96.67 8 97.16 95.35 93.80 92.60 72.2 69.00 69.00 9 99.99 - 99.96 - 99.89 99.92 98.20

Example 5 was found to exhibit very good performance properties, particularly for critical cleanroom wiping applications, as tested by newly developed methods. In addition, the entangled lyocell fabric of Example 9 has been found to be a good candidate for cleanroom applications, which is particularly important in dynamic wiping efficiency (DWE). In addition, the entangled fabrics of pulp / polyester (Examples 1 and 2) and lyocell / polyester (Example 4) from the results of the particle removal capability (PRA) test showed that When tested in volume, it was found to show surprisingly high grades. These examples of low-cost entangled fabrics represent an important step forward for use in general wiping applications, particularly important cleanroom applications. The nonwovens of the invention, equivalent to and often exceeding the performance of the knitted fabrics of the comparative examples, were considered as industry standards, particularly in clean room applications.

It should also be noted that meltspun nonwovens having substantially continuous filament polymer fibers will be useful in the present invention. Such fabrics have continuous filaments as in the knit fabric. The polymer fibers are polyester or polypropylene or bicomponents of polyester and polypropylene as described in the co-pending US patent application Ser. No. SS-2911, filed Dec. 20, 1999 and also assigned to DuPont. Fiber.

<Example 10-13>

Example 10 is Clean Room Laundry DyNamix ™ 6900QL used in Example 5. Comparative Example 11 is Sontara® Style 8007, which is essentially the same fabric as in Example 10, except that it was not washed in a clean room. Comparative Example 12 was Sontara® Style 8000 with a basis weight of 39.9 g / m ² and not washed but treated with a surfactant to improve its absorbency. Comparative Example 13 is a SUPERPOLX 1200, polyester knitted fabric washed in the same manner as in Example 3.

The examples were tested for various static properties using the tests as described above, as well as the DWE and PRA tests. The results are shown in Table 6.

Example 10 11 12 13 Basis weight (g / m ² ) 113 110 39.9 142 Fiber / cm ² 1.3 4.2 24 0.26 particle Biaxial shaking, 10 ⁶ / m ² 18 10 270 16 Absorbency (cc / m ² ) 627 510 232 469 Non-absorbent (cc / g) 5.5 4.6 5.8 3.3 1/2 Absorption Time (sec) One > 300 2 One Ions (ppm) Na 0.5 8.4 66 0.31 K 0.16 1.4 2.3 0.12 Ca 0.16 22 18 0.11 DWE at 10 ml challenge (%) 98.4 25 1-ply 94.7 3-ply 99.7 98.9 PRA on 10 ml challenge (10 ³ particles remain on the surface) 11 5310 1-ply 498 3-ply 13.6 73

Example 10 showed good cleanliness data, low fiber divergence and good absorbency. This also exceeds the microsuspension example in ion contamination.

Comparative Example 11 was fairly clean based on biaxial shaking water, but showed moderate to high fiber divergence and very poor absorption.

Comparative Example 12 was insufficient when compared at particle loading, absorption capacity and rate, extractable material, and ion loading. Surfactant treatments helped to increase absorbency but resulted in an undesirable large number of ions. Surprisingly, however, the fabric showed a PRA approaching the PRA of Example 10 when using a three-ply structure.

Comparative Example 13 was similar to the Example in terms of biaxial shaking particles and ions. There was a continuous filament, which resulted in low fiber divergence, but did not perform as the fabric of the present invention in absorbent capacity.

The particle removal capability test results showed excellent cleanliness of the fabric of the present invention of Example 10, leaving only 11,000 particles to 10 × 10 ⁶ particle conductive liquid as compared to 5.3 × 10 ⁶ particles left by the micro-turk control Comparative Example 11. Indicated. Example 10 was particularly suitable as it performed better than Comparative Example 13, which left 73,000 particles in its mark. In particular, surprisingly, the fabrics of the present invention exhibited excellent performance in good absorbency and particle removal (functional cleanliness) as well as good cleanliness as measured by normal static means.

Claims (23)

Used for wiping non-wovens comprising fibers selected from the group consisting of polyesters, lyocells and blends of polyesters and lyocells in a grade 10 or cleaner clean room as measured by US Federal Standard Act FED-STD-209E. How to. The method of claim 1 wherein the dynamic wiping efficiency of the fabric is at least 89% at a conductive volume of 10 milliliters. The method of claim 1 wherein the dynamic wiping efficiency of the fabric is at least 70% in a conductive volume representing 130% of the absorbent capacity of the fabric. The method of claim 1 wherein the particle removal efficiency of the fabric is at least 98% at a conductive volume of 10 milliliters. The method of claim 1 wherein the particle removal efficiency of the fabric is at least 96% in a conductive volume representing 130% of the absorbent capacity of the fabric. The method of claim 1 wherein the nonwoven comprises about 42% lyocell and about 58% polyester. The method according to any one of claims 1 to 6, wherein the nonwoven is made by entanglement. Wiping material comprising a polyester nonwoven fabric used in clean room cleanliness, as determined by U.S. Federal Standards Act FED-STD-209E. delete delete delete delete delete delete delete A wiping material comprising a nonwoven comprising a lyocell and a fiber selected from the group consisting of lyocells and blends of polyester and lyocell and used in a grade 10 or cleaner clean room as measured by US Federal Standard Act FED-STD-209E. 17. The wiping material according to claim 8 or 16 wherein the nonwoven is entangled. The wiping material according to claim 8 or 16, wherein the basis weight of the fabric is at least about 102 g / m ² . 17. The wiping material according to claim 8 or 16, wherein the dynamic wiping efficiency of the fabric is at least 98% at a conductive volume of 10 milliliters. 17. The wiping material according to claim 8 or 16, wherein the dynamic wiping efficiency of the fabric is at least 70% in a conductive volume representing about 130% of the absorbent capacity of the fabric. 17. The wiping material according to claim 8 or 16, wherein the particle removal efficiency of the fabric is at least 99% at a conductive volume of 10 milliliters. The wiping material according to claim 8, wherein the particle removal efficiency of the fabric is at least 96% in a conductive volume representing 130% of the absorbent capacity of the fabric. 17. The wiping material according to claim 8 or 16, adapted for use in a Class 10 or cleaner cleanroom as measured by FED-STD-209E.