Disposable towelettes and similar sheet products, sometimes generally referred to as "wipes", which are dispensed from a container, or from individually wrapped packages, have become a fixture in today's society. For example, wipes are used for hygienic purposes as well as routine, nonhygienic cleaning and wiping. The size, shape, thickness, durability, moisture content, and lotion content of the wipe can all be adjusted for a variety of uses, and the versatility of such products has contributed to the popularity of wipes in general.
Due to the variety of uses for sheet products such as wipes, they have taken on numerous physical forms, and their dispensing mechanisms have likewise been varied. There are a variety of dispensing mechanisms that involve containers and some that do not. For example, rolls of dry paper towels and toilet paper do not require containers because of their low moisture content. "Dry" sheet products often include lotions or other additives and are not necessarily moisture free. Rather "dry" sheet products are sheets with low moisture content that are generally dry to the touch of an average consumer. Paper towels and toilet paper are generally in the form of rolled continuous sheets with perforations defining the individual leaves. A consumer unrolls the number of leaves that he or she needs and tears them from the roll along the perforations between leaves.
Often sheets are premoistened with lotions, cleansing agents or the like. A popular method for dispensing moistened sheets, "wet wipes", is a combination of the perforated roll and the container dispenser. Ribbons of sheets are often perforated, rolled, placed in a rigid container and then lotions and/or cleansing agents are added. For dispensing, individual wet wipes are generally pulled through a small aperture in the container and then tom along the perforations to remove the sheet. Problems with such arrangements can arise as the dispensing aperture is typically small to minimize evaporative loss of moisturizing agent from the products closest to the top. The smaller sized aperture, in turn, requires an increase in force to withdraw the wipe from the dispenser. The increased force can result in premature tearing of perforations between products to be dispensed, or may require designing perforations with increased resistance to tearing, thereby requiring additional force by the user to separate a product for use. Often, two hands are required to extract a treated or "wet wipe" (i.e. one hand to remove a wipe and the other to secure the container while the wipe is being removed from the container and tom from the next wipe). Unfortunately, however, sheet products such as wipes are often needed when only one hand is available (e.g. when cleaning an infant), which makes rolled perforated wipes dispensed from a container an undesirable combination due to the high dispensing forces which may lift the container.
Another common form of wipes that is not dispensed from a rigid container includes the individual prepackaged wet wipes often handed out at restaurants or on airplanes. These wet wipes are often folded and placed in individual moisture resistant pouches, then lotion and/or a cleansing agent is added, and the pouch is heat sealed. The consumer tears open the package to use the wipe, and then disposes of both the pouch and the wipe. Typically, this is also a two-handed operation, and there is considerable waste created in the form of the individual pouches, making this method of packaging and dispensing undesirable as well.
For generally dry sheets, a known manner of dispensing individual (i.e. pre-cut, interfolded, non-perforated) sheets is through a dispensing container. The dispensing container can be a box with a lid that is opened each time a sheet is needed, it can be a box with a lid and an aperture that individual sheets are pulled through, or it can be a combination of both a lid and an aperture. Generally dry sheets dispensed through a box with an aperture are typically rectangular and interfolded. Tissues and paper towels in restrooms are often dispensed in this manner.
As currently practiced, dispensing an interfolded sheet involves pulling one edge of an essentially rectangular sheet away from the dispenser. The interleaved portion of the two sheets serves to pull the adjacent portion of the next sheet due to the interfacial interaction of the two sheets at the overlap area. After the first sheet has been completely pulled through the aperture the two interfolded sheets begin to quickly separate. When the two sheets are completely separated, there should be a sufficient amount of the second sheet extending outside of the dispensing aperture to allow easy subsequent access to the second sheet. The portion of the second sheet remaining above the dispenser is commonly referred to as the "tail".
Dry sheets or tissues dispensed in this manner generally have a large overlap area consisting of an entire side of the rectangular sheet interfolded with an edge of the next sheet. However, as moisture is added to a sheet product, the large surface area of overlap often results in excessive interactive forces between the two sheets, causing a second sheet to be dispensed along with the first sheet due to the larger force required to separate the two sheets. Decreasing the surface area of overlap is difficult because this decreases the adhesive force, which controls the amount of the second sheet removed from the dispenser (to provide the "tail" for subsequent dispensing).
Currently, sheets that are moist, thick and non-woven, can not be dispensed by interleaving the sheets, as, due to the adhesion between sheets caused by the presence of high levels of moisture, the force required to separate two sheets is so great that multiple sheets are often dispensed with one pull (sometimes called "chaining"). Therefore, the sheets are typically folded individually and stacked one on top of the other and placed in a dispensing container. This dispensing method is less than optimal because there is no convenient tail to grab when a sheet is needed, generally resulting in a more difficult two-handed dispensing procedure.
U.S. Pat. No. 5,332,118 to Muckenfuhs (the '118 patent), discloses a series of designs for sheets that can be folded and used in an interleaved pop-up dispensing mechanism without the dispensing difficulties discussed above. The entire disclosure of the '118 patent is hereby incorporated herein by reference. An improved sheet design and method for forming sheet products, as described in the '118 patent, for use in pop-up dispensing applications is provided herein.
Methods for cutting continuous ribbons with variable edge geometries have been described in a variety of references. For example, a continuous web can be cut into continuous ribbons by pulling the web over a rotating drum and contacting the web with a rotating blade. The blade can be stationary, which creates a ribbon with straight edges parallel to the machine direction, or it can oscillate in a direction perpendicular to the machine direction to create edges that are at least partially non-parallel to the machine direction.
Another method of cutting irregular shapes on the edge of a continuous traveling web is to use a frame to hold multiple cutting devices, which may include water jets, lasers or blades. Multiple frames may also be used for the purpose of cutting shaped fabric pieces or for cutting shaped voids into a continuous fabric web. Another method of cutting a continuous woven web is with heated blades in order to seal the woven edges and to prevent the woven material from unraveling at the edges of the sheet.
Automated methods for folding a series of continuous ribbons into a continuous strata of overlapping sheets for use in a pop-up dispensing system are known to the art. Machines of this type have been used for folding continuous ribbons that have edges which are essentially straight and parallel to the longitudinal axis of the ribbons, e.g. tissues. Once the ribbons are interfolded, interleaved continuous stacks are produced, which are cut into blocks suitable for use in a pop-up dispenser.
Clearly, prior devices separately teach specific folding means, but continuing enhancement of sheet products for improved pop-up dispensing performance, as well as a better method for economically and efficiently producing such products, has been needed. There is a continuing need for improved sheet products and a method of manufacturing sheets that can be used effectively in a pop-up dispensing system. Further, there is a need for an improved process whereby ribbons can be, overlapped accurately and consistently, folded and cut into sheets for use in a pop-up dispensing system.