Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2001-12-21
2004-08-31
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S034200, C428S057000, C428S058000, C428S332000, C428S480000, C428S481000, C428S483000, C428S507000, C428S511000, C428S514000, C428S522000, C004S245600, C004S245800, C004S245900, C004S450000, C004S452000, C004SDIG001
Reexamination Certificate
active
06783826
ABSTRACT:
RELATED APPLICATION
This application is one of two related applications filed on the same day. The other application Ser. No. 10/026,197 is entitled “Latently Dispersible Barrier Composite Material” with inventors Ann L. McCormack and Richard L. Shick, herein incorporated by reference.
BACKGROUND
For commode liners it is desired to contain and/or temporarily prevent passage of aqueous waste or other aqueous materials, and at some later time dispose of the barrier material in a clean and environmentally friendly manner. To be effective, the material of the commode liner should temporarily provide a barrier to leakage, and at the appropriate time desirably break up into components that facilitate suitable disposal, especially by flushing down a toilet, while minimizing adverse effects on the environment.
Prior containers using water sensitive layers of, for example, polyvinyl alcohol (PVOH) exist. Difficulties have been identified with these prior containers because many water sensitive materials like PVOH become dimensionally unstable when exposed to conditions of moderate to high humidity and tend to weaken or stretch. In use, for example, the material can stretch out of shape and/or weaken to the point of rupture. Attempts to add stability by increasing the barrier film thickness, for example, add unacceptable cost and/or increase the issues to be addressed upon disposal. Commode liners made of thicker films have a greater tendency to remain intact on flushing, for example, and clog toilets or downstream systems.
The need continues, therefore, for commode liners providing temporary barrier, latently dispersible properties that are stable under use conditions but also easily disposable under aqueous conditions as by flushing, for example. There is also a need to design the shape of the commode liner to maximize its flushability, especially when disposed of in a modern low water usage toilet. The present invention addresses this and similar needs.
SUMMARY OF THE INVENTION
The present invention includes commode liners of a unique design that are easily flushed by modern low volume toilets. A commode liner using this design is formed from a first and a second opposing member joined together forming a top including an opening, a bottom, and a pair of opposing sides having a separation distance D. The separation distance D varies from the top to the bottom, and the distance D is larger at the top than at the bottom. Thus, the commode liner is tapered and easily flushed by a toilet.
The present invention is also directed at commode liners formed from latently dispersible barrier composites using a low strength barrier layer of water insoluble composition combined with a water sensitive, low strength carrier and on the opposing side of the carrier an inextensible, dispersible support layer. The layers of the commode liner material are bonded and provide a barrier to aqueous liquid contact from one side but the combination disperses when contacted by aqueous liquid from the other side. In use as a commode liner convenient and environmentally sensitive disposal may be achieved. Examples of barrier layers include films or fine fibers of very lightweight construction using polymers such as polylactic acid or polycaprolactone. Examples of water sensitive carrier webs include films of PVOH with or without other components. Examples of inextensible support materials include higher modulus or low stretch toilet tissue grades.
Where all component layers of the commode liner material are biodegradable and/or dispersible, disposal by flushing is facilitated. For many applications it will be desirable to maintain component layers as light or low basis weight as is compatible with the intended use. In particular, the barrier layer may not be readily dispersible if it is of increased thickness. Cost will provide an incentive to reduce the weight of the component layers, particularly for single use applications. Many commode liner applications will use a barrier layer of polylactic acid (PLA) having a thickness in the range of from about 0.5 to about 2.0 microns, PVOH film carrier layer having a thickness in the range of from about 10 to about 50 microns, and a tissue support layer in the range of from about 10 to about 30 gsm, for example. As a result, the composite for the commode liner will desirably have a hydrohead property of at least about 15 mbar, for some applications at least about 25 mbar, for more demanding applications at least about 50 mbar, and in some cases at least about 75 mbar. Bonding of the layers may be by a variety of means that preserve desired properties, including thermal (such as coextrusion or extrusion coating, for example) and adhesive, pattern and smooth bonding means.
Definitions
As used herein unless the context requires a different meaning, the following terms have the meanings set forth below:
As used herein and in the claims, the term “comprising” is inclusive or open-ended and does not exclude additional unrecited elements, compositional components, or method steps.
As used herein the term “nonwoven fabric or web” means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91).
As used herein the term “meltblown fibers” means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin et al. Meltblown fibers are microfibers that may be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are generally tacky when deposited onto a collecting surface.
“Bonded carded web” refers to webs made from staple fibers which are sent through a combing or carding unit, which breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction-oriented fibrous nonwoven web. Such fibers are usually purchased in bales that are placed in a picker that separates the fibers prior to the carding unit. Once the web is formed, it then is bonded by one or more of several known bonding methods. One such bonding method is powder bonding, wherein a powdered adhesive is distributed through the web and then activated, usually by heating the web and adhesive with hot air. Another suitable bonding method is pattern bonding, wherein heated calendar rolls or ultrasonic bonding equipment are used to bond the fibers together, usually in a localized bond pattern, though the web can be bonded across its entire surface if so desired. Another suitable and well-known bonding method, particularly when using bicomponent staple fibers, is through-air bonding.
“Airlaying” is a well-known process by which a fibrous nonwoven layer can be formed. In the airlaying process, bundles of small fibers having typical lengths ranging from about 6 to about 19 millimeters (mm) are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply. The randomly deposited fibers then are bonded to one another using, for example, hot air or a spray adhesive. Examples of airlaying technology can be found in U.S. Pat. Nos. 4,494,278, 5,527,171, 3,375,448 and 4,640,810.
Kerins John E.
McCormack Ann L.
Sherrod Earle H.
Shick Richard L.
Baum Scott A.
Chen Vivian
Connelly Thomas J.
Kimberly--Clark Worldwide, Inc.
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