Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Reexamination Certificate
2000-09-27
2002-07-16
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
C428S161000, C428S167000, C264S293000, C264S316000, C264S320000, C005S417000
Reexamination Certificate
active
06420015
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a cushioned dust control mat or article. In one embodiment, the mat comprises at least two distinct layers of rubber, one comprising foam rubber, the other comprising solid rubber. The solid rubber layer is present over the foam rubber layer on the side of the mat in which at least one. integrated rubber protrusion is present to provide cushioning characteristics. The solid rubber layer acts as a cap or barrier for the foam rubber layer, particularly over the integrated protrusion or protrusions, in order to provide a mat which is resilient, will not easily degrade in its modulus strength after appreciable use and/or washing within industrial cleaning processes, and will not exhibit appreciable cracking or breaking, particularly within the integrated protrusion(s), after standard use for pedestrian traffic. A method of producing such an inventive cushioned floor mat article is also provided.
BACKGROUND
All U.S. patent cited herein are hereby fully incorporated by reference.
As described U.S. patent application Ser. No. 09/374,707, filed Aug. 13, 1999, now U.S. Pat. No. 6,340,514, and in corresponding Japan Patent Application No. 353345/99, filed Dec. 13, 1999, floor mats have long been utilized to facilitate the cleaning of the bottoms of people's shoes, particularly in areas of high pedestrian traffic such as doorways. Moisture, dirt, and debris from out of doors easily adhere to such footwear, particularly in inclement weather and particularly in areas of grass or mud or the like. Such unwanted and potentially floor staining or dirtying articles need to be removed from a person's footwear prior to entry indoors. As will be appreciated, such mats by their nature must undergo frequent repeated washings and dryings so as to remove the dirt and debris deposited thereon during use. These mats are generally rented from service entities which retrieve the soiled mats from the user and provide clean replacement mats on a frequent basis. The soiled mats are thereafter cleaned and dried in an industrial laundering process (such as within rotary washing and drying machines, for example) or by hand and then sent to another user in replacement of newly soiled mats.
Uncarpeted anti-fatigue dust control mats have been made in the past comprised of dense rubber, scrap rubber, sponge-like material, including PVC, vinyl polymers, and polyurethanes, as well as recycled tire rubber. The mats are generally not able to be washed in industrial cleaning applications (such as rotary washing machines) since they are either too heavy or dense (and thus either damage the machine or themselves) or either deteriorate too easily (since sponge-like materials are easy to tear apart, particularly in rotary cleaning applications). Such washability is a key to providing a suitable floor mat article within the standard rental laundry market. As such, it has been very difficult to produce uncarpeted cushioned floor mats which exhibit sufficient strength to withstand vigorous cleaning and laundering associated with industrial rental laundry services. Foam rubber has only recently been utilized within dust control mats as a manner of reducing the overall mass of the mat article to facilitate movement and cleaning (such as in U.S. Pat. No. 5,305,565 to Nagahama et al.). Also, cushioned mats have been produced, generally including portions of the mat which contain discrete areas of integrated rubber increasing the surface area of the mat in three axes, which thereby provide cushioned areas on which a pedestrian may step.
However, other than as described in previously mentioned U.S. application Ser. No. 09/374,70, now U.S. Pat. No. 6,340,514, and Japan application 353345/99, there have not been any mats comprising integrated rubber protrusions which not only permit repeated industrial washings without exhibiting appreciable degradation of the mat structure but also provide excellent cushioning effects to pedestrian users for more comfortable floor and ground covering as well as provide a surface to clean such pedestrians' footwear. As such, there is a need to provide an improved durable, cushioned dust control mat and method.
DESCRIPTION OF THE INVENTION
It is thus an object of this invention to provide a durable, cushioned dust control mat which permits cleaning of a pedestrian's footwear. Furthermore, it is an object of the invention to provide a durable, cushioned dust control mat in which the cushioning aspects are provided by at least one integrated rubber protrusion produced during the necessary vulcanization process. Still other objects of the invention is to provide a cushioned all-rubber floor mat which retains its cushioning characteristics and shape upon use and can be laundered repeatedly within industrial rotary washing machines without damaging such machines or themselves.
Accordingly, one embodiment of this invention encompasses a rubber floor mat structure comprising at least two separate layers of rubber wherein said at least two layers comprise
a first layer comprised of foam rubber; and
a second layer comprised of solid rubber;
wherein at least one protrusion integrated within said rubber mat structure is present having a core portion and an outside surface portion, wherein the core portion of said at least one protrusion is comprised of said first layer of foam rubber, wherein the outside surface portion of said at least one protrusion is comprised of said second layer of solid rubber, and wherein the protrusions are star shaped and the mat surface in the area surrounding the protrusions is ribbed or grooved to provide additional cleaning of a pedestrian's footwear.
Further, the protrusions are preferably arranged in a tire tread like arrangement or footprint with groups and rows of groups of protrusions.
The first rubber layer may be comprised of any standard rubber composition, including, but not limited to, acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), carboxylated NBR, carboxylated SBR, chlorinated rubber, silicon-containing rubber, and the like, all of which must include a blowing agent to form the necessary closed-cell structure of the resultant foam rubber, such as in U.S. Pat. No. 5,305,565 to Nagahama et al. For cost purposes, the preferred rubbers are NBR, SBR, and blends thereof.
As noted above, the foam rubber component is important in this inventive floor mat. Dust control mats have exhibited general problems arising from frequent washings and harsh environments of use. First, the energy required to wash and dry a typical floor mat is significant due to the overall mass of the mats. The overall mass is most significantly attributed to the mass of the rubber within the mat. As will be appreciated, a reduction in the overall mass of the floor mat will result in a reduced energy requirement in washing and drying the mat. Moreover, a relative reduction in the mass of the rubber provides a substantial benefit. Thus, the utilization of a lighter weight rubber composition, such as foam rubber, in at least a portion of the dust control mat of the present invention includes a rubber backing sheet which may possess a specific gravity which is approximately 25 to 35 percent less then the rubber sheets of typical prior floor mats. Accordingly, a foam rubber is the bottom layer of the mat and the core layer of the integrated rubber protrusion(s) of this invention. Such a foam rubber layer is present as a thicker layer than the solid rubber cap (generally). The target thickness for such a first layer is from about 15 to about 500 mils, preferably from about 25 to about 400 mils, more preferably from about 40 to about 350 mils, and most preferably from about 75 to about 250 mils. The resultant lighter weight of the mat structure thus translates into a reduced possibility of the mat harming either the washing or drying machine in which the mat is cleaned, or the mat. being harmed itself during such rigorous procedures. Although the inventive floor mat must withstand the rigors of industrial machine wash
Kobayashi Seiin
Nagahama Yuji
Nord Thomas D.
Alexander Daniel R.
Loney Donald J.
Milliken & Company
Moyer Terry T.
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