Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1998-08-07
2003-03-11
Lo, Weilun (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S365000, C604S367000, C604S390000, C604S385050, C428S040100, C428S041800
Reexamination Certificate
active
06530910
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a flushable release liner/wiper combination. The flushable release liner/wiper combination is formed by applying a release coating onto at least one surface of a water-sensitive film and attaching a wiper to the opposite surface of the water-sensitive film. The flushable release liner/wiper combination maintains its structural integrity and strength when in use, but begins to disperse when placed in contact with water. When placed in a conventional sink or toilet, the flushable release liner/wiper combination quickly loses its integrity and strength and breaks up under the forces of flowing water. Moreover, the present invention is directed to products, including flushable and non-flushable products, which contain the flushable release liner/wiper combination.
BACKGROUND OF THE INVENTION
Disposable products have revolutionized modern lifestyle and are of great convenience to society. Such products generally are relatively inexpensive, sanitary and quick and easy to use. Disposal of such products, however, is a concern as landfills close and incineration contributes to urban smog and pollution. Consequently, there is an urgent need for disposable products that can be disposed of without dumping or incineration. An ideal disposal alternative would be the use of municipal sewage treatment plants and private residential septic systems. Products suited for disposal in sewage systems that can be flushed down a conventional toilet are termed “flushable.” An essential feature of flushable products is that they must have sufficient strength for their intended use, yet lose structural integrity upon contact with water.
Numerous consumer products, which were formerly unable to be disposed of in a conventional toilet, are made flushable today. Such products include water-soluble films, wipers, tampon applicators, etc. However, many consumer products have remained unflushable.
One such product that has remained unflushable to date is release liners. Release liners are used to temporarily cover an adhesive layer before use in many personal care products. The release liner provides protection for the adhesive layer against exposure to materials, which might negatively affect the ability of the adhesive strip to adhere to a desired substrate, and provides protection against undesired, premature adhesion to a substrate. Conventional release liners comprise a paper substrate coated with a release coating. The release coating is formulated to provide very little adhesion of the coated paper to any other substrate, particularly pressure-sensitive, hot-melt adhesives, so the release liner may be easily removed from the adhesive strip without disturbing the adhesive strip. Typically, release coatings comprise a silicone-containing polymeric material.
Release liners are used in many personal care products. For example, many sanitary napkins have an adhesive strip on the backside of the napkin (the napkin surface opposite to the body-contacting surface) to fix the napkin to an undergarment and hold the napkin in place against the body. Before use, the adhesive strip is protected with a peelable release liner. Once removed, the peelable release liner must be discarded. Since conventional peelable release liners are typically silicone-coated paper, the release liners do not disperse in water; consequently, disposal options are limited to depositing the release liner in a trash receptacle. Although disposing of conventional release liners in a toilet would be convenient to the consumer, such improper disposal potentially creates blockages in the toilet or household sewer line.
Further, conventional peelable release liners, once removed from an adhesive strip, have very little utility. Consumers typically dispose of the release liner immediately after removal from the adhesive strip. Often a consumer wishes to wipe the perineal area of the body prior to using a new sanitary napkin. With conventional release liners, the consumer must resort to using a separate wiping product, such as bath tissue, to wipe the perineal area.
What is needed in the art is a low-cost flushable release liner/wiper combination, which can be discarded and then flushed in a conventional toilet. Such a flushable release liner/wiper combination would function as a release liner having additional utility as a wiper, eliminating the need to use a separate product to wipe the perineal area of the body prior to using a new sanitary napkin. Such a flushable release liner/wiper combination would offer convenience to the consumer, and not cause problems such as blockages in the sewage transport process.
SUMMARY OF THE INVENTION
The present invention is directed to a flushable release liner/wiper combination comprising a thin release coating on a first surface of a water-sensitive film and an absorbent wiper attached to a second surface of the water-sensitive film, which is opposite the first surface. The coated water-sensitive film/absorbent wiper combination functions like conventional release papers and wiping materials currently used. Conventional release papers comprise a peelable coated paper, which covers the adhesive strip on a feminine sanitary napkin. Unlike conventional release papers, the coated water-sensitive film/absorbent wiper combination of the present invention provides utility as a wiper and rapidly loses integrity and strength when discarded in a conventional toilet. Without the support of the water-sensitive film, the thin release coating and absorbent wiper material begin to break up under the force of flushing. The three-layer structure of the flushable release liner/wiper combination offers (1) the performance of a paper-based release liner with a wiping surface, (2) the additional option of disposal in a toilet, and (3) potentially lower cost.
The present invention is also directed to a method of preparing a flushable release liner/wiper combination. The method comprises coating a thin layer of polymer having release characteristics onto a base film, wherein the base film comprises a water-sensitive polymer. When dry, the resulting two-layer laminate displays mechanical features comparable to a conventional coated paper liner. The base film itself may be manufactured, taking into consideration variables such as film thickness, molecular weight, and blending additives, to control the functionality of the plastic film. The polymeric coating controls the release characteristics of the plastic film. The coating is formulated to provide very little adhesion to many substrates, particularly pressure-sensitive, hot-melt adhesives, so that the coating may be easily removed from an adhesive strip without disturbing the adhesive strip, while having high adhesion to the water-sensitive film substrate. The coating formulation ensures that the two-layer polymer film peels at the surface of the release coating, not at the interface between the coating and the water-sensitive base film.
The coated water-sensitive film is further combined with an absorbent fibrous material such that the fibrous material provides a wiping surface on the film opposite to the release coating. The fibrous material may be attached to the film by any means known to those of ordinary skill in the art, desirably by extrusion lamination. The fibrous material, independent from the coated film, may be flushable/dispersible when placed in contact with water, such as found in a conventional sink or toilet.
The present invention is also directed to articles containing the flushable release liner/wiper combination. Specifically, the flushable release liner/wiper combination of the present invention is useful in connection with a variety of products, and especially absorbent products such as sanitary napkins, panty liners, diapers, dressings and the like. Although the release liner of the present invention finds particular use in the above-mentioned products, the concept of a flushable release liner/wiper combination has potential for any other application requiring a release material.
The present inven
Chang Yihua
Kerins John E.
Pomplun William S.
Bogart Michael G.
Kilpatrick & Stockton LLP
Kimberly--Clark Worldwide, Inc.
Lo Weilun
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