TECHNICAL FIELD CONTAMINANT CLEANER This invention relates to the manufacture of fabric cleaners, in particular, cleaners that release less contaminants and / or contaminants into less offensive particles while, however, exhibit good absorptivity and strength. BACKGROUND OF THE INVENTION
[0002] Cleaners can be made from knitted, woven or non-woven fabrics of materials such as polyester and the like. The typical manufacturing process begins with stretching and texturing continuous filament yarn. The textured yarn is knitted or knitted to build a fabric, and the fabric is washed or cleaned to eliminate spinning oils. The fabric can be chemically modified in order to improve its wetting and performance. The fabric is then dried in a "stiffening bast" oven to remove moisture and heat-adjust the fabric. The heat setting dissipates the stress in the polyester fibers and stabilizes the fabric. Next, the fabric is cut into cleaners, typically square of 22.86 cm by 22.86 cm (9 inches by 9 inches). Cleaners can remain unwashed or can be washed in a cleaning room laundry, using special surfactants and. highly filtered and purified water, to reduce the contamination present in the fabric. After washing, the cleaners can be packed dry in air-tight plastic bags, or presaturated with an appropriate solvent before packing. These cleaners are used for a number of different applications, including cleaning / inside cleaning rooms, automotive paint rooms and other environments where particulate contaminants are undesirable. Each different application emphasizes certain standards that these types of cleaners must achieve. For example, for cleaners used in hygienic rooms, strict performance standards must be met. These standards are related to sorbency and contamination, including maximum permissible particles, extractable matter, unspecified and individual ionic contaminants. The rules for the release of particular pollutant are especially rigorous and several methods have been designed to fill them. For example, Paley et al., Patent of E.U.A. No. 4,888,229
(incorporated by reference) discloses a cleaner having melted edges, the sealed edge of the cleaners being present to reduce contamination caused by small fibers. Diaber et al., Patent- of E.U.A. No. 5,229,181 (incorporated by reference) describes a tube of knitted fabric, only two edges from which it must be cut and sealed, thereby reducing contamination caused by loose fibers from the edges. Paley et al., Patent of E.U.A. No. 5,271,995, (incorporated by reference) describes. a cleaner for a hygienic room environment that has reduced inorganic contaminants through the use of a specific yarn, to say "nylon shine". Reynolds, Patent of E.U.A. No. 5,069,735 (incorporated by reference) describes a procedure for. Cut the fabric into pieces using a hot air jet on the scale of 316 to 427 ° C (600 to 800 ° F) to melt the fibers, forming a sealed edge product with reduced loose fiber contamination. Despite the advantages made in reducing the release of particulate pollution from hygienic room cleaners, however, they are. highly desirable additional reductions in particle release. COMPENDIUM OF THE INVENTION In accordance with one aspect of the invention, a suitable low contaminant cleaning fabric for a wide range of applications is provided. 'The cleaner substantially fills all specifications for use in hygienic rooms, particularly those specifications for Class 100 hygienic rooms and below.
In accordance with another aspect of the invention, a hygienic room cleaner is provided which has a high capacity for liquid sorbency. In accordance with still another aspect of the invention, a cleaning fabric is provided which has substantially stable edges which are not subject to fracture which generates substantial particles during application of stresses applied during normal use1. In accordance with yet another aspect of the invention, a cleaning cloth is provided which incorporates threads of substantially reduced inorganic ion content so as to reduce the effects of any releasable particles. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is. will now be described by way of example only, with reference to the accompanying drawings, which constitute a part of this specification and in which: Figure 1 is a elevational plan view of a mode of a cleaner in accordance with this invention; Figure 2 is a view. taken along line 2-2 in Figure 1; Figure 3 is an elevational plan view of another embodiment of a cleaner in accordance with the present invention; Figure 4 is an elevational plan view of yet another embodiment of a cleaner in accordance with the present invention; and Figure 5 is a view taken along line 5-5 in Figure 4. Although the invention has been illustrated and will be described below in detail in connection with certain potentially preferred embodiments and practices, it should be understood that the above general description as well as the following detailed description and accompanying drawings are exemplary and explanatory only and in no case is the invention intended to be limited thereto. On the contrary, it is intended that the present invention extends to all alternatives, modifications and equivalents that may encompass the broad principles of this invention within the true spirit and scope thereof. DESCRIPTION OF PREFERRED MODALITIES Reference will now be made to the drawings, where to the extent possible, like elements are designated by like reference numbers throughout the various views. All of the US patents cited within the specification are hereby incorporated by reference in their entirety as being fully set forth herein. In accordance with the potentially preferred practice, the cleaners of the present invention can be constructed of a multiplicity of woven or knitted yarns of polyester fiber, preferably poly (ethylene terephthalate) fibers. This yarn is preferably a continuous filament polyester yarn even if other types and yarn constructions may also be used, if necessary. It is contemplated that yarns having a wide variety of denier and filament count characteristics may be employed. Examples of useful yarns can include those having a denier to filament ratio of about 0.1 to about 10, incorporating deniers of about 15. to about 250. A wide variety of fabric weights can be employed in the fabric cleaners. present invention. : Typically, the fabrics used for hygienic room cleaners have a weight of about 34 to about 305.15 grams per square meter (1 to 9 ounces per square yard), and more preferably about 101.72 to about 237.34 grams per square meter '(3 to 7 ounces per square yard). If desired, it is contemplated that the yarn employed in the fabric may be a texturized polyester yarn. These yarns are commercially available and their manufacture is well known to those skilled in the art. Briefly, partially oriented yarn (POY) is modified by rippling, imparting random ties, or otherwise modifying the surface volume or texture of the yarn to increase the cover, absorbency, elasticity, abrasion resistance, heat, insulation and / or to improve the aesthetics. A general description of the texturing process can be found in the Encyclopedia of Textiles, Fiber, and Non-Woven Fabrics, Encyclopedia Reprint Series, De. Martin Grayson, pages 381-398, John Wylie and Sons (1984) and Dictionary of Fiber and Textile Technology, Hoechst Celanese (1989). During the texturing process, the wire preferably is not heated above a temperature of 149 ° C (300 ° F) and usually does not heat above about 107 ° C (225 ° F). In accordance with a potentially preferred practice of the present invention, once formed, the fabric is preferably subjected to washing and heat setting procedures as described in the U.S. Patent. 6,189,189 to Morin et al. (Incorporated by reference). In particular, the fabric is preferably dried and thermofixed at a temperature of about 82 ° C. at about 149 ° C (180 ° F to 300 ° F) and more preferably from 93 ° C to 135 ° C (200 ° F to 275 ° F) and more preferably from 107 ° C to 129 ° C (225 ° C) F at 265 ° F). The heat setting temperature is preferably adjusted to a temperature higher than that to which the yarns have previously experienced. This thermofixed treatment is believed to improve the performance criteria applied to cleaners for use in environments of, hygienic room including sorbency, as well as both, the amount and size of generated particles. In general, it is desired that hygienic room cleaners exhibit high levels of sorbency while generating low levels of particulate contaminants during use. In addition, it is desired that those particulate contaminants that may be generated have low levels of inorganic ionic constituents such as metal constituents that can influence the operation of the small scale integrated circuit. It has been recognized that during the use of a cleaner, the edges of the cleaner can result in a disproportionately high level of particle generation. The theory is made that such disproportionate particle generation arises from the breakage of fiber elements along the high energy surfaces at the perimeter edges of the cleaner. To alleviate this problem it has been proposed to melt the edges of the wipers either just along the edge or in a substantially solid melting zone extending a distance inward from the edge towards the interior of the wiper. These melted zones can be imparted by melting the fibers within the zones by use of delivered energy from a source of directional heat application. However, the melted edges or extended edges may tend to reduce the elasticity in those areas relative to the rest of the cleaner. In this way, during a stretching of the cleaner, the melted edges or extended edges may tend to undergo premature localized fracture, thereby releasing material into potentially unwanted particles. In accordance with a first embodiment of the present invention as illustrated in Figure 1, a cleaner 10 formed of knitted polyester yarns is provided. While a woven knit construction of substantially 100% polyester may be preferred, it is also contemplated that other constructions including woven and nonwoven constructions and other fibers including nylon and the like may also be used, if desired. As shown, the cleaner 10 includes an interior cleansing surface 12 and a multiplicity of perimeter edges. In the illustrated and potentially preferred embodiment, the cleaner 10 is of a substantially quadrilateral geometry so that the cleaner 10 includes a first perimeter edge 14 and a second perimeter edge and a fourth perimeter border 20 extending over the perimeter. a generally right angle relationship in re the first perimeter edge 14 and the second edge 16 of perimeter. While the cleaner 10 is illustrated as being substantially square in configuration, it should also be understood that the cleaner 10 can take any number of other geometries including, by way of example only, and not limitation, a rectangular configuration or some other configuration of Multiple convenient sides such as a triangular, pentagonal, hexagonal or octagonal geometry, as desired. As will be seen, the cleaner 10 is cut from a much larger continuous ribbon of cloth having an extended length and a width sufficient to provide multiple cleaners. In accordance with a potentially preferred practice, the wiper 10 is cut from said larger web of cloth in accordance with a pattern so that the first and second perimeter edges 14, 16 extend in the so-called "crossed machine direction" arranged substantially transverse to the elongated direction of the continuous fabric belt. Correspondingly, the third and fourth perimeter edges 18, 20 are preferably cut substantially along the so-called "machine direction" of the fabric generally parallel to the elongated direction of the continuous fabric belt. As illustrated, the first perimeter edge 14 and the second perimeter edge 16 extending in the transverse machine direction are each preferably provided along their length with a bprde 24., 26 sealing formed by a cutting operation with hot blade or laser, in order to seal the fibers a. along the primary cut edge of the cleaner 10. In addition, the first and second perimeter edges 14, 16 are each preferably provided with an inwardly extending discontinuous fused edge 28, 30 extending inward from the edges 24, 26 sealed adjacent to the interior surface 12 of the cleaner. As shown, discontinuous fused edges 28, 30 are preferably made of a multiplicity of discrete bonding points 34, 36 in which thermoplastic fibers such as polyester forming cleaner 10 have undergone localized melting, melting together in this way : during the resolidification. It is contemplated that the bonding points 34, 36 extending in the cross machine direction may be applied in a previously defined pattern of repetition using a design enhancing element such as an ultrasonic horn operating on one side of the fabric that The cleaner 10 forms in relation opposite an anvil with a surface design disposed on the opposite side of the fabric forming the cleaner 10 within a width corresponding to the desired width for the inwardly extending discontinuous fused edges 28, 30. Of course, other fusion techniques with design can also be used such as using a bracket with design on one side of. the fabric and applying a hot ironing element through the opposite side so as to apply the series of bonding points 34, 36. In accordance with the illustrated and potentially preferred practice, discontinuous fused edges 28, 30 extending in the transverse machine direction preferably have a relatively narrow width in the range of about 0.3 mm to about 1.6 mm and more preferably will have a width in the scale of about 1.0 mm to about 1.4 mm even though greater or lesser depths may also be used, if desired. As shown, in accordance with one embodiment, the link points 34, 36 may be sub-rectangular in configuration arranged in a brick-like pattern within discontinuous fused edges 28, 30 such that the length dimension of the dots 34, 36 extends generally parallel to the outer sealed edges 24, 26. Of course, it is contemplated that any number of other geometric arrangements may also be used including, by way of example only, and not of limitation, substantially circular discrete link points, elongated elliptical link points, square link points, and other geometries. In addition, due to their discontinuous nature, the linking points can also be arranged in a pattern in the form of an icon conveying message such as a corporate logo, patent number or the like. In accordance with the. illustrated practice wherein the bonding points are substantially rectangular in configuration, the rectangles forming the bonding points are preferably of the scale of about 0.75 mm wide by about 3 mm long and are spaced approximately 1 mm apart 'in defined rows. The rows are preferably approximately 0.5 mm apart with the tie points in adjacent rows being slightly offset from one another in a stepped relationship. It is believed that the use of discontinuous fused edges 28, 30 reduces the generation of particulate matter during the application of tension in a direction parallel to said edges allowing the force to be dispersed more evenly through the matrix formed by the interstitial areas between the bonding points 34, 36, thereby reducing the concentration of force that can lead to localized fiber breakage. It is contemplated that the load distribution can be further improved by pretensioning the cleaner 10 in the transverse machine direction before the introduction of the edges 28., 30 discontinuous castings. In accordance with a potentially preferred practice, the prestressing of the fabric can be carried out by stretching the fabric forming the cleaner 10 during the introduction of the bonding points 34, 36, thereby essentially holding in a stretched relationship. This stretching can be carried out by the use of a stretching frame or by other means as will be well known to those skilled in the art. After the release of the fabric following the introduction of the attachment points 34, 36 a portion of the extension is released into the body of the cleaner 10 but the points 34,
36 are used to hold substantially in a stretch along the perimeter edges 14, 16. As shown, the third and fourth perimeter edges 18, 20 extending in the machine direction preferably have a slightly different configuration.
As best seen by simultaneous reference to Figures 1 and 2, the perimeter edges 18, 20 extending in the machine direction of the cleaner 10 are preferably formed by bending the edges inwardly so as to form edges 38, 40. of double layer. Inwardly from the double layer edges 38, 40, the melt-cast fastening zones 48, 50 'are applied to thereby seal the double layer edges 38, 40 in place. As shown, according to one embodiment, the fixing zones 48, 50 can be made from a pattern of fusion bonding points 44, 46 formed by localized designed fusion of polyester or other thermoplastic fiber constituent in the manner above described. However, if desired, the fixation zones 48, 50 may also be in. the form of solid melt-fused strips extending inwardly from the inner edge of the double layer edges 38, 40. The double layer edges 38, 40 which are preferably uniform and substantially free of fusion bonding points provide a shore structure that is not substantially susceptible to fiber fracture during drawing and thus is believed to promote the integrity of the structure. the edges during the stretching, thus reducing the generation of particles. The fixation zones 48, 50 (either solid or discontinuous in nature) are preferably sufficiently broad so that a stable fusion bonding relationship is established. By way of example only, and not limitation, in case the attachment areas are made of discrete link points 44, 46, as shown, wherein the link points 44, 46 are of a substantially rectangular configuration that it has a width in the scale of about 0.75 mm and a lh in the scale of about 3 mm arranged in a deviated brick pattern in rows separated by approximately 0.5 m, it is contemplated that at least about 3 and more preferably about 4 or more of said rows are used. Of course, other geometries for the link points 44, 46 as described above in connection with the fused edges 28, 30 extending in the cross machine direction can also be used, if desired. As with the link points 34, 36, which extend along the cross machine direction of the cleaner 10, it is contemplated that the link points 44, 46 arranged along the machine direction can be applied by use of any fusion linkage device with appropriate design, including by way of example only, and not limitation, an ultrasonic linkage apparatus using an anvil wheel with rotating design or a heat sink holder, with pattern used in conjunction with a heat source of ironing. In accordance with one practice, it is contemplated that the formation of the wiper 10 can be carried out in a highly efficient and automated manner by continuously slotting an elongated web of fabric to provide multiple parallel strips of desired width.
This cut can be used out: using 'A laser or hot blade for; seal the side edges. The strips are transported along a path of travel through an edge bending apparatus in which a blade or blade element is used to continuously bend the side edges of the strips so as to form the edges 38, 40. of double layer desired. The strips are then passed through ultrasonic bonding stations arranged generally transverse to the path of travel of the strips in which the dots
44, 46 that form the fusion zones 48, 50 along the lateral perimeter edges are applied. By way of example only, it is contemplated that the ultrasonic link stations used to form the points 44, 46 be linked into the zones 48 ,. Fusion 'can generally be similar to the device illustrated and described in the US patent. 6,001,442 to Rockwell, Jr., (incorporated by reference) which incorporates elongated horns and anvils with rail-like design oriented in the direction of travel of the strips. The inwardly extending discontinuous fused edges 28, t 30 extending in the transverse machine direction below are applied across the width of the strips. segmented by ultrasonic link units that incorporate an elongated horn and back anvil with
The design is similar to the original rail, generally transverse to the path of the strips. The cleaner 10 is segmented from the strip by use of a hot or laser blade, which serves to form the sealed edges 24, 26. Of course, any number of other automated or manual techniques can be used, if desired. As will be appreciated, the present invention is susceptible to a wide range of alternative constructions. By way of example only, one of said alternative constructions is illustrated in Figure 3, wherein the elements corresponding to those described in relation to Figure 1 are designated with like reference numbers increased by 100. As shown, the mode of Figure 3 is substantially identical to that of Figure 1, except that the double layer edges 38, 40 have been replaced by extended discontinuous melting zones 148, 150 that extend substantially to the adjacent perimeter edges 118, 120. In Figure 4 there is still illustrated another embodiment of the present invention, in which the elements corresponding to those previously described in relation to Figure 1 are designated by similar reference numbers increased by 200. As shown, in this embodiment, the Double layer folded edge structures are applied along each of the perimeter edges 214, 216, 218 and 220. This configuration results in the occurrence of double-layered edges 260, 262 extending in the machine direction transverse along the first and second perimeter edges 214, 216 with discontinuous fused edges 228, 230 disposed inwardly thereof as shown in FIG. shown in Figure 5. Said configuration is believed to further reduce the potential for particle generation during the use of the cleaning cloth 210. Of course, if desired, the discontinuous fused edges 228, 230 may be replaced by substantially continuous fusing zones, such as strips extending inwardly from the double layer edges 260, 262. In addition to the reduction in particle generation potential as the edges of the cleaner are stretched, the present invention further contemplates the relative impact of said particles. can be substantially reduced through the selection of building materials that make up the cleaner. In accordance with a potentially preferred practice, the cleaners of the present invention are formed of polymeric fibers that incorporate very low levels of inorganic additives. In particular, the fibers forming the cleaner of the present invention are preferably formed of the so-called "bright" or "transparent" polyester. · Said fiber is substantially free of titanium dioxide Ti02) or other
i -f H i-i- 1 | hiúú · ui Mítf < -ffi-fryn i'ír • | • -r- ¾H- itítwi½- ^ metal-based opacifying agent cdflro "is commonly used to impart the traditional bright white character associated with polyester, titanium dioxide and other metal ion compounds They are prone to acid extraction towards solution when placed in a highly acidic environment., that many electronic manufacturing processes use highly concentrated acid solutions such as sulfuric acid (H2SO4) has been recognized by the. Applicants It may be desirable to reduce the presence of said ionic constituents within any particles that may be generated so as to prevent the accumulation and potential concentration of said ions within acidic room solutions that can be used a number of times. In accordance with the potentially preferred practice, the fiber forming the cleaner according to the present invention is preferably characterized by a concentration of inorganic ionic constituents at a level such that during complete combustion of the fiber, the remaining ash content is in the scale of less than about 0.30% of the initial and most preferred fiber weight is on the scale of about zero to about 0.15 of the initial fiber weight and more preferably is on the scale of about zero to about 0.3% of the initial fiber peséis. One said fiber which may be desirable in the formation of the cleaner according to the present invention is believed to be available from E. I. DuPont de Nemours which is believed to have a place of business in Wilmington, Delaware. Test The level of particle generation associated with hygienic room cleaner edges of various constructions has been determined. Stretching a 6-centimeter segment of cleaner's edge of interest to a length corresponding to the elongation that occurs during the application of 2.72 kilos' (6 pounds) force tension. This stretch occurs with the wiper edge retained in the vertical position on a 14 cm funnel at the end of an isokinetic probe linked to a particle counter carried by the air. The inverted cleanser segment was stretched and held in tension for a period of 2 seconds and removed while still tense. The resulting count of generated particles greater than or equal to approximately 0.3 microns was recorded, during counter stabilization. The invention can be. further understand by reference to the following comparative examples.
EXAMPLE 1"A" style sanitary room cleaner, having b fde constructions substantially as illustrated and described in relation to Figures 1 and 2 with bent edges of double layer in the machine direction and discontinuous fused edges in the direction of Transverse machine was formed of balanced knitted fabric knitted tightly constructed of double knit knit construction made of 70 denier polyester thread 36 filaments with 41 relieves by 2.54 cm (1 inch) x 40 turns by 2.54 cm and one weight of 125.45 grams per square meter (3.7 ounces per square yard). Segments of both, the double-layer bent edges in the machine direction and the discontinuous edges in the cross-machine direction in thirty-one of the cleaners were tested for particle generation under stress application in accordance with the test procedure as is described above. The results of said test are shown in Table 1. EXAMPLE 2 A "B" style sanitary room cleaner formed as described in Example 1 was formed having thermally sealed edges on both the machine direction and the cross machine direction . The heat seal was carried out in accordance with the teachings of the U.S. Patent. 5,069,735. The edge segments in the machine direction and in the cross machine direction in thirty-one of the cleaners were tested for generation of particle under tension in accordance with the test procedure as described above. The results of said test are set forth in Table 1. EXAMPLE 3 A "C" style sanitary room cleaner having fused edges extending inwardly as described in U.S. Pat. 4,888,229 to Paley et al., In both the machine direction and the cross machine direction was obtained from a commercial source. The fabric that forms the cleaner was made of 70 denier 34 filament polyester yarn in a double knit construction with 37 reliefs by 2.54 cm X 47 turns by 2.54 cm with a weight of 142.40 grams per square meter (4.2 ounces per Square yard) . The edge segments in the machine direction and in the cross machine direction in thirty-one of those cleaned were tested for particle generation under voltage application in accordance with the test procedure as described above. . The results of said test are shown in Table 1. EXAMPLE 4. A hygienic room cleaner "D" was formed having thermally sealed edges in both the machine direction and in the cross machine direction. The heat seal was carried out in accordance with the teachings of the US Patent.
5, 069, 735. The loom * forming the cleaner was UB¾ construction of double knit fabric of 70 denier polyester threads 36 filaments quo has 43 reliefs by 2.54 cm x 37 rows by 2.54 cm and a weight of 119.35 grams per square meter (3.52 ounces per square yard). The 1 edge segments in the machine direction and in the cross machine direction in thirty-one of the cleaners were tested for particle generation under the application of; voltage in accordance with the test procedure as described above. The results of this test are shown in Table 1. Table 1 Style of A A B B C C D > C Cleaner Direc-Direc-Direc-Direc-Direc-Di ec- Directionalization of m-de-ma-de-ma-de-mas-machine machine machine machine machine machine machine trans-trans-trans-machine, cross machine versal versal versal
Measurement of average particle count 409 1357 3702 1433 2875 3731 2030 1598
Measurement of high particle count 936 2205 5955 2754 6018 7173 3712 2601
Low Particle Count Measurement 84 203 1471 402 1020 1643 879 682 Normal Deviation 233 604 1455 556 1251 1634 721 614
Lower Security Limit! Statistical average 301 1078 3029 1176 2296 2975 1697 1314
Upper Security Limit Statistical Average (99%) 516 1636 4375 1690 3454 4487 363 1882 It is believed that this data confirms that the double-edge construction of the "A" style cleaner results in a dramatic improvement in both the average and real particles generated in tension on what is believed to have been available so far. Also, in regions where a non-bent extended edge zone is used, the discontinuous fused edge construction that extends into the "A" style of cleaner provides a much lower particle generation than the solid molten edge that extends into the style cleaner
While the present invention has been illustrated and described in relation to certain modalities. Potentially preferred constructions and procedures, it should be understood and appreciated that such embodiments, constructions and procedures are illustrative and exemplary only and that the present invention is in no way to be imitated thereto. Rather, it is contemplated that modifications and variations that modalize the principles of the present invention will undoubtedly occur to those of experience in the field to which the invention pertains. Therefore, it is contemplated and intended that the present invention extends to all these modifications and variations as they may incorporate the broad principles of the invention in the spirit and complete scope thereof.