Textiles: knitting – Fabrics or articles – Articles
Reexamination Certificate
1999-07-22
2001-10-30
Worrell, Danny (Department: 3765)
Textiles: knitting
Fabrics or articles
Articles
C066S202000, C066S16900R
Reexamination Certificate
active
06308538
ABSTRACT:
BACKGROUND OF THE INVENTION
Technical Field
The present invention relates generally to special purpose wipers and, more particularly, to a plurality of flat wipers and method of making the same by a continuous knitting operation which periodically incorporates a dissolvable yarn that, when wetted, dissolves and leaves a plurality of individual wipers.
BACKGROUND OF THE INVENTION
Special purpose wipers are known in the art for use in controlled environment facilities such as cleanrooms that require the maintenance of an extremely clean environment. The wipers are typically used to clean and prepare surfaces while at the same time avoiding contamination of the environment by particulates or lint from the wiper. Critical environments can be found in hospitals and medical facilities, the pharmaceutical, aircraft and automotive industries, as well as in optical, electronics, and nuclear facilities. Cleanrooms are characterized by a special emphasis on the prevention of particulate generation and the removal thereof prior to deposition on cleanroom surfaces and products to avoid reentry into the air at a later time. A classification system is often observed in the wiper market which categorizes the controlled environment according to the efficiency with which particulates are removed from the air.
Wipers for use in the cleanest classification of cleanrooms typically have a knitted construction, as opposed to a woven or non-woven construction. The knit construction is preferred because, unlike woven or non-woven materials, knitted material is produced by knitting a continuous filament or yarn, thereby resulting in a finished product with fewer loose ends or short fibers. Woven and non-woven materials can be comprised of hundreds or thousands of fibers, portions of which can be released from the material to become particulate contamination in cleanroom environments.
The cost of a knitted product depends to an extent on the method used to make the finished product. Articles which are knitted individually tend to be more expensive than those cut from a large section of knitted material. However, problems exist when articles are cut from a large section of knitted material. By partitioning a continuous knitted sheet, filaments or yarns of the sheet are severed, leaving many loose ends extending from edges of each partitioned section, which then require some type of edge sealing or preparation procedure to prevent the ends from disassociating. Known methods of edge preparation include melting the loose ends with a heating element, cutting the large sheet with a hot wire, laser or ultrasound machine, which simultaneously cuts and seals the ends. Wipers used in the cleanest classification of cleanrooms require a final step of laundering the wipers prior to packaging to dislodge and remove any loose particles or fibers.
A wiper disclosed in U.S. Pat. No. 5,229,181 typifies the labor intensive processes associated with manufacturing methods known in the art. This wiper is produced by a circular knitting machine which knits a continuous cylinder of material. Once the cylinder is removed from the machine, it is ultrasonically point bonded to create a flat two-ply tube which is then cut and sealed perpendicularly across its longitudinal tube axis into individual, tubular wipers of specified lengths. The sealing operation prevents disassociation and fraying of loose fiber ends.
A manufacturing method used to make anoth John C. Hilton closed in U.S. Pat. No. 4,888,229. The wipers are produced by first knitting a sheet of indeterminate dimensions. A pattern is impressed upon the sheet of material by fusing together the fibers in the knit, with the pattern corresponding to the future borders of individual wipers. Once the pattern is formed, the sheet of material is separated into individual wipers by cutting along the pre-formed borders. Alternatively, a heated knife or wire may be used to simultaneously cut the knit fibers and seal the edges. A final wash cycle is required to dislodge any loose fibers prior to packaging.
The industry needs a more effective manufacturing method which requires fewer processes and less equipment to produce individual wipers. The present invention is drawn toward such an article of manufacture and a method for producing the same.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to knit a wiper to a desired size.
It is a another object of the present invention to manufacture a wiper having no edge-sealing requirements after the wiper is knitted.
It is yet another object of the present invention to manufacture a knitted web of material to length which has selvaged side edges.
According to the present invention, a knitted web includes a first wiper and a second wiper knitted from a continuous strand of a primary yarn and a continuous strand of a reinforcing yarn, each of the first and second wipers defined peripherally by opposed, outside, selvaged side edges and finished leading and trailing edges, and a separator portion knitted between said finished trailing edge of said first wiper and said finished leading edge of said second wiper using a dissociable yarn. A plurality of wipers is created by cutting the continuous strands of yarn extending between the first and second wipers and removing the dissolvable portion.
One feature of the present invention is the knitting method which creates wipers with selvaged side edges that require no treatment after being knit to prevent raveling.
Another feature of the present invention is the knitting method which creates wipers with finished leading and trailing edges that require no treatment after being knit to prevent raveling.
Still another feature of the present invention is the dissociable yarn which, when removed, leaves the wipers separated and in a finished state.
Yet another feature of the present invention is the knitting method which reduces the number of manufacturing steps required to create a plurality of wipers.
These and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of best mode embodiments thereof as illustrated in the accompanying drawings.
REFERENCES:
patent: 2263787 (1941-11-01), Safferson
patent: 3331221 (1967-07-01), Lawson
patent: 3470928 (1969-10-01), Schwartz
patent: 5069735 (1991-12-01), Reynolds
patent: 5520022 (1996-05-01), Callaway
patent: 5594970 (1997-01-01), Benge
patent: 5605731 (1997-02-01), Guasch Pubill
patent: 5667612 (1997-09-01), Benge
Forbes Bradley L.
Fountain Christopher J.
O'Connell John
Romer Richard H.
Simmons, Jr. Peter S.
Berkshire Corporation
McCormick Paulding & Huber LLP
Worrell Danny
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