Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
1999-12-29
2001-07-31
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C521S050000, C428S113000, C428S634000, C428S402000
Reexamination Certificate
active
06268048
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions for manufacturing breathable and flushable films, fibers and articles. Particularly, the present invention relates to compositions and films comprising a blend of a water-responsive polymer of ethylene oxide and particles selected from the group consisting of clay and layered silicate particles.
BACKGROUND OF THE INVENTION
Disposable personal care products such as pantiliners, diapers, tampons, etc. are a great convenience. Disposable products provide the benefit of one time, sanitary use and are convenient, quick and easy to use. However, disposal of these products is a concern. Incineration of these products is also not desirable because of increasing concerns about air quality and the costs and difficulty associated with separating these products from other disposed, non-incineratable articles. Dumping of these products is also undesirable due to concerns with limited landfill space and increasing land cost. Consequently, there is a need for disposable products which may be quickly and conveniently disposed of without dumping or incineration.
It has been proposed to dispose of these products in municipal and private sewage systems. Ideally, these products would be flushable and degradable in conventional sewage systems. Articles suited for disposal in sewage systems that can be flushed down conventional toilets are termed “flushable.” Disposal by flushing provides the additional benefit of providing a simple, convenient and sanitary means of disposal. Personal care products must have sufficient strength under the conditions in which they will be used. Thus, it is desirable for personal care products to withstand the elevated temperature and humidity conditions encountered during use, yet lose integrity upon contact with water in the toilet. It is also desirable that these personal care products are breathable in order avoid the build-up of perspiration and increase the level of comfort of the consumers of these products. Therefore, a breathable material having mechanical integrity when dry and that readily disintegrates upon immersion in water is highly desirable.
Due to its unique interaction with water and body fluids, poly(ethylene oxide) (hereinafter PEO) is currently being considered as a component material for water-sensitive compositions. PEO,
—(CH
2
CH
2
O)
n—
is a commercially available, water-responsive polymer that can be produced from the ring opening polymerization of the ethylene oxide,
Because of its water-responsive properties, PEO is desirable for flushable applications. However, conventional PEO films are not as breathable as desired for many personal care applications and are difficult to process using conventional processing techniques.
Many have attempted to overcome these difficulties. U.S. Pat. No. 4,902,553 to Huang et al. describes disposable articles comprising a liquid impermeable, vapor permeable film. The liquid impermeable, vapor permeable film described by Huang et al. comprises a crystallizable, stretched polyolefin-based film and a rattle-reducing additive which may be poly(ethylene oxide). However, the liquid impermeable, vapor permeable films of U.S. Pat. No. 4,902,553 require at least one nucleating agent which may be talc or calcium carbonate and stretching to achieve breathability. The amounts of nucleating agent are limited to very small amounts, 0.05 to 5 percent by weight. These amounts of inorganic, nucleating agent are insufficient to be defined as fillers. Further, stretching is required to generate porosity and hence breathability and subsequent leaching of the rattle-reducing agent is desired. In contrast, the films of the present invention are based on a water-responsive polymer and not the non-water-soluble and non-water-degradable polyolefins described by Huang et al. Advantageously, the films of the present invention do not require stretching, a nucleating agent or a crystallizable polyolefin for breathability.
U.S. Pat. No. 3,895,155 describes coated, transparent plastic articles. The transparent plastic may comprise poly(ethylene oxide). An inorganic, protective coating is applied as a separate layer over the transparent plastic article to improve surface hardness, increase stretch resistance, and facilitate non-fogging. The inorganic, protective coating may comprise various metal oxides. However, the coating forms a separate, discrete, glass-like layer from the transparent plastic article and the resulting coating and articles are not breathable or flushable.
U.S. Pat. Nos. 5,075,153, 5,244,714, and 5,672,424 to Malhotra et al. describe multilayered or coated recording sheets designed for electrostatic printing processes. The recording sheets comprise a base sheet with an anti-static layer, which may be made from poly(ethylene oxide). The recording sheets comprise an additional toner-receiving layer, which comprises inorganic oxides such as silicon dioxide, titanium dioxide, calcium carbonate, or the like. The poly(ethylene oxide) and inorganic oxides are contained in separate layers, the anti-static layer and the toner-receiving layer respectively. Further, the recording sheets are not breathable or flushable.
U.S. Pat. No. 4,276,339 to Stoveken describes a laminated product comprising a paper layer and a foamed layer. Poly(ethylene oxide) is described as one of many possible components of an aqueous dispersion of latexes from which the foamed layer is made. Inorganic fillers such as clay or silica are suggested as possible additions to the aqueous dispersion of latexes in order to increase the solids content and density of the aqueous dispersion of latexes. The aqueous dispersion from which the foamed layer is made must be capable of being foamed and requires foaming in order to be breathable.
Thus, currently available PEO films are not practical for breathable or flushable applications. What is needed in the art, therefore, is a means to efficiently and economically produce breathable and flushable films, fibers and articles and a method of controlling the breathability of these breathable and flushable films fibers and articles. Further, what is needed in the art is a composition for making water-responsive, environmentally degradable and breathable films that do not require stretching, foaming, air entraining or a foaming agent in order to be breathable.
SUMMARY OF THE INVENTION
The present invention provides compositions having enhanced breathability comprising a water-responsive polymer, that is optionally environmentally degradable, and unmodified clay particles. Desirable water-responsive polymers include polymers and copolymers of ethylene oxide. Desirable clays include various clays and layered silicate that have not been organically modified. Films, fibers and articles made from the compositions of the present invention may be incorporated into personal care articles that are flushable and optionally environmentally degradable that require breathability.
Films made from the compositions of the present invention possess a unique nanoporous structure. The unique nanoporous structure is believed to provide enhanced breathability. Films, fibers and articles made from the compositions disclosed herein can be manufactured such that the films, fibers and articles are both breathable and flushable. Advantageously, the films, fibers and articles can be made breathable without stretching or foaming of the film, fiber or article and the breathability is enhanced and can be controlled.
The water-responsive polymer component of the compositions of the present invention forms the matrix of the composite and the clay particles are dispersed throughout the polymer matrix. An example of the unique nanoporous microstructure possessed by films formed form compositions of the present invention is provided in FIG.
1
. The structure can be described as an “enveloped house of cards,” where the cards are clay platelets and bundles and stacks of clay platelets and the PEO is the polymer coating enveloping and holding the cards in their positions. It is believed th
Eby Thomas A.
Topolkaraev Vasily A.
Acquah Samuel A.
Kilpatrick & Stockton LLP
Kimberly--Clark Worldwide, Inc.
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