Brushing – scrubbing – and general cleaning – Implements – Tool coated or impregnated with material supply
Reexamination Certificate
1999-08-28
2001-08-07
Spisich, Mark (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Tool coated or impregnated with material supply
C015S209100, C442S340000
Reexamination Certificate
active
06269513
ABSTRACT:
BACKGROUND OF THE INVENTION
Wipes are well known commercial, consumer, and industrial products relied upon to assist in the removal of contaminants from surfaces. They are available in a wide variety of materials fashioned into relatively thin sheets. The earliest wipes were probably woven rags and these were replaced to some degree by thin sheet paper products. Unfortunately, rags and cellulosic paper products tend to shed fiber particles, and to tear, so that they can not be used to decontaminate surfaces to the low particulate levels required by many modern-day manufacturing processes.
Improved wipes followed the development of processes to produce filaments from synthetic polymeric materials such as the “meltblowing” process as described in U.S. Pat. No. 3,978,185 to Bunting et al. dated Aug. 31, 1976. This led to the substitution of such synthetic filaments for the cellulosic filaments by compressing and bonding the filaments into sheets, for example as given in U.S. Pat. No. 4,307,143 to Meitner, dated Dec. 22, 1981. Although these products had improved strength, and a reduced tendency to shed filaments, they were still relatively weak. Since the fibers were bonded and permanently compressed, they had a diminished interstitial volumes and therefor diminished abilities to absorb liquids. Modest absorption improvements resulted from creating patterned indentations in the sheet of polymer filaments as exemplified in U.S. Pat. No. D0,409,389 to May et. al., dated May 11, 1999.
The foregoing wipes all suffered from an inability to remove substantial amounts of solids contaminants because they could do so only by the attachment of the contaminant solids to the surface of the wipe, since the act of compressing and bonding of the filaments tended to create a fiber web which restricted the passage of solids contaminants into the interior of the wipe. Also, since these wipe products were in the form of thin two dimensional sheets, they had very little interior volume. Furthermore, since the filaments of the wipes were in a restrained and bonded state, particles which did find their way into the interstices of the fiber webs were not readily trapped could pass back out again, particularly if the wipes were used moistened or otherwise wetted with a carrier or solvent liquid.
Many laminate fabric species have been proposed during the last several decades in which sheets of meltblown filaments are compressed and bonded to external layers of substantially continuous non-woven “spunbonded” filaments. A recent example is given in U.S. Pat. No. 5,804,512 to Lickfield et. al. dated Sep. 8, 1998. These have increased strength, but the meltblown filaments are bonded, compressed, and restricted, and therefore have a limited ability to capture particles irreversibly and to absorb liquids. Also, these laminates tend to be stiff and therefore do not have the flexibility or “drape” required for a wipe to conform readily to the surface being decontaminated. Reduced conformation results in a corresponding reduction in wiping efficiency with an increased possibility that some sections of the surface being cleaned would be bypassed under the conditions which would reasonably occur in manufacturing operations.
The liquid absorptive capacities of the wipes described above could be enhanced by increasing their thickness. However, this would result in unacceptably high levels of stiffness.
Recent advances in manufacturing and processing technologies, and environmental concerns, have created a demand for more stringent levels of cleanliness. This has produced a corresponding need for economical wipe products that can provide increased capacities to remove contaminant solids, and to absorb cleaning liquids, coincident with low wipe fiber shedding, high wipe strength, and minimum wipe stiffness.
SUMMARY OF THE INVENTION
The invention resides in a wipe constituted from a compressible bed of loose and discontinuous ultra-fine filaments which filaments include a significant number of sub-micron diameter filaments. Methods for making suitable micro filaments, including sub-micron diameter microfilaments, are described in U.S. Pat. No. 4,363,464 to Torobin dated Dec. 14, 1982, U.S. Pat. No. 4,525,314 to Torobin dated Jun. 25, 1985, and U.S Pat. No. 4,536,361 to Torobin dated Aug. 20, 1985. On a commercial basis, suitable micro filaments are available from Nanofiber Technology Incorporated, Aberdeen, N.C.
The ultra-fine microfilaments are contained and sealed in a pouch made from a deformable porous material which is permeable to the contaminant solids particles being removed. The contaminant solids particles are removed by rubbing the solids-contaminated surface being cleaned with the wipe, employing a rubbing pressure sufficient to cause the contaminant solids to pass through the apertures in the permeable surface and to contact the bed containing the ultra-fine filaments. The rubbing pressure causes the particles to be forced further into the interior of the bed of loose ultra-fine microfilaments where the particles are trapped, in part due to the attractive contact forces on the surface of the ultra-fine microfilaments and mechanical entanglement. The solids are thereby prevented from passing back out through the solids-permeable walls of the pouch. Also, the apertures of the pouch material are selected to be sufficiently small to prevent the leakage of significant amounts loose ultra-fine microfilaments to the exterior of the pouch. Such leakage could result in “linting” which would contaminate the surface being cleaned.
The strength and particle shedding requirements for the wipe are addressed by proper selection of the pouch material only. The selection of the internal ultra-fine microfilaments is then freed to focus on the liquid and solids absorption performance required by the wipe user. This invention therefor provides a unique ability to uncouple the physical property considerations, allowing each element to be optimized to a level previously unattainable.
The passage of the contaminant solids through the wall of the wipe may be facilitated by the use of a lubricating solids-transporting liquid which is selected to be a non-solvent for the particular contaminant solids particles being removed and non-solvent for the pouch material or the interior loose ultra-fine microfilaments. Appropriate solids-transporting liquids include those with relatively high vapor pressures which eventually evaporate and do not remain on the originally solids-contaminated surface after the solids are removed by the wipe. To augment the surface forces capturing the contaminant solids in the ultra-fine microfilaments, the transporting fluid may be selected to have a positive wetting contact angle with respect to the contaminating solids and to the material constituting the loose ultra-fine filaments.
The use of loose super-fine filaments including sub-micron filaments promotes the rapid and uniform distribution of the solids transporting liquid throughout the wipe.
Excessive movement of some or all of the loose ultra-fine microfilaments contained in the pouch can be minimized by establishing occasional point attachments of opposite walls of the pouch by conventional means such as heated point bonding or ultrasonic point bonding.
The pouch used to contain the loose fine filaments may be made of any flexible fabric or membranous material which contains openings sufficiently large to allow the passage of the contaminant solids but sufficiently small to prevent the leakage of significant quantities of the contained ultra-fine microfilaments. Accordingly, it may be fabricated from woven or non woven essentially continuous filaments which have sufficient strength not to break or otherwise become detached during the rubbing action described above. The filaments constituting the fabric employed as the walls of the pouch may be from fiber forming organic compounds such as the thermoplastic or thermosetting polymer resins. Alternatively, they may be made from inorganic fiber forming materials including ceramic, glass, or metal composi
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