Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,...
Reexamination Certificate
2002-03-22
2003-04-29
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
C428S362000, C428S371000, C428S402000
Reexamination Certificate
active
06555219
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a soil substitute useful in supporting plant growth. More particularly, the present invention relates to biodegradable and non-biodegradable polymer fibers for use in plant cultivation.
BACKGROUND OF THE INVENTION
In the conventional cultivation of plants, regardless of being indoor or outdoor, naturally produced soil has been used as the medium for storing and supplying the nutrients, air, and moisture necessary for raising plants. It is now well known in the art that artificial media can be used for the germination, rooting and propagation of plants. Media such as peat moss, vermiculite, perlite, wood bark, sawdust, certain types of fly ash, pumice, plastic particles, glass wool, and certain foams are commonly used, or have been disclosed in the literature, either alone or in various admixtures with each other and/or soil.
Although these prior art media are useful and have achieved commercial acceptance in many areas, they do not provide an optimal balance between water and the gases that can significantly influence root and total plant growth. It is well known that plants growing in such commonly used media identified above can, under some conditions, suffer from lack of oxygen or show symptoms commonly believed to be caused by over-watering, i.e., chlorosis, slow growth, pale color, and even death.
U.S. Pat. No. 5,363,593 (Hsh) describes a synthetic cultivation medium comprised of fibrous glomerates and a method of manufacturing the same. Absent a soil component, the synthetic cultivation medium is manufactured from scrap, man-made textiles, chiefly polyacrylonitrile or polyester fibers. Scrap textile fabrics are shredded into short fibers and chemically refined and bleached. Prior or subsequent to the chemical refinement and bleaching, the short fibers are agitated into glomerates of intertwined fibers. The fiber length is preferably <10 mm, and the diameter of the glomerates is preferably within the range of 2-8 mm. Hsh's uncrimped fiber glomerates are dense and thus wick water more and hold less water than a medium that is less dense. These fiber glomerates are likely to revert back to fibers upon vigorous or prolonged contact. In addition, the glomerates of Hsh are described therein as nearly invulnerable to the degradative effects of natural decomposition.
It is a purpose of the present invention to provide a method of supporting plant growth which eliminates or minimizes the plant growth problems mentioned above.
It is a purpose of the present invention to provide a method of supporting plant growth which provides a plant growth medium that upon the addition of water and appropriate nutrients, can be used for the germination of seeds and growth of seedlings, the vegetative propagation and growth of other plant material, and the growth of plants to maturity or some other stage of growth and development.
It is a further purpose of this invention to provide a method of supporting plant growth by providing a plant growth medium that that can be used to replace all or a substantial amount of conventional materials such as normal soils, soil mixtures, clay, vermiculite, perlite, peat moss, bark wood shavings or chips, and the like, thus substantially improving total water holding ability and maintaining a more optimal balance between solids, water, and gases.
A further purpose of the invention is to provide a method of supporting plant growth which provides a plant growth medium that can be biodegradable to serve as a soil substitute or a soil supplement for starting seedlings to be transplanted to fields. Such a medium would exhibit considerable water retention and high property retention for a period of time prior to transplanting, but would after a certain period of time thereafter be sufficiently degraded to be “plowed under”.
SUMMARY OF THE INVENTION
The present invention concerns a method of supporting plant growth, comprising contacting plant material with a plant growth medium comprising fiberballs in an amount effective to support plant growth, each fiberball consisting essentially of randomly-arranged, entangled, crimped polymer fiber having a cut length of about 0.5 to about 60 mm.
In one preferred embodiment, the plant growth medium comprises biodegradable fiberballs prepared from polyester fibers. In another preferred embodiment, the plant growth medium comprises non-biodegradable fiberballs prepared from polyester fibers.
DETAILED DESCRIPTION OF THE INVENTION
The present invention concerns a method of supporting plant growth, comprising contacting plant material with a plant growth medium comprising fiberballs in an amount effective to support plant growth, each fiberball consisting essentially of randomly-arranged, entangled, crimped polymer fiber having a cut length of about 0.5 to about 60 mm.
Various types of natural and synthetic organic polymer fibers are suitable for use in the present invention. Synthetic organic polymer fibers are preferred. As used herein, the term “synthetic organic polymer fibers” includes fibers prepared from polymers such as polyesters; polyacrylonitrile; polyvinyl alcohol; polyolefins; polyamides, such as nylon; acrylics; polylactides; and the like; as well as polymers derived from cellulose, such as viscose rayon, cellulose acetate; and the like. Blends of any of the foregoing polymers are also useful in the present method, for example nylon and polyester. Preferred synthetic organic polymers for making fiber useful in the present method are polyester, polyamide, or blends thereof. Polyethylene terephthalate is most preferred.
The term “natural organic polymers” includes polymers such as wool, cotton, jute, silk, hemp, bagasse, cellulose, and blends thereof. Preferred natural organic polymers are cotton, cellulose, bagasse, and hemp.
The fibers useful in the present invention can comprise hollow or solid fibers and are generally made from polymer fibers in staple form of various cut lengths. The fibers for use in the plant growth medium of the method of the present invention generally are staple fibers having a cut length in the range of about 0.5 mm to about 60 mm. Silicone slickeners may be added to the fiber to improve lubricity and aesthetics. Such silicone slickeners are added by coating the fibers with the slickeners in an amount about 0.15 to about 0.5% Si by weight of the fibers (see U.S. Pat. Nos. 4,618,531 and 4,783,364, incorporated by reference herein).
The fibers used in preparing the fiberballs herein are crimped. Spirally crimped fibers, i.e. fibers having a 3-dimensional helical crimp are preferred. Such crimping can be provided by asymmetric jet-quenching of freshly-extruded filaments, as taught, e.g. in Killian U.S. Pat. Nos. 3,050,821 and 3,118,012 incorporated by reference herein, or by the method disclosed in Evans et al., U.S. Pat. No. 3,671,379, incorporated by reference herein. Most preferred are spiral crimps in the form of an omega-crimp, as disclosed in U.S. Pat. No. 4,783,364, incorporated by reference herein. Fibers with 2-dimensional saw-tooth crimp induced by mechanical means, such as a stuffer box, can also be used herein.
The polymer fibers are used herein in the form of fiberballs. By “fiberball” is meant polymer fibers which have been formed into substantially rounded bodies. The fiberballs preferably have an average dimension of about 1 to 15 mm, at least 50% by weight of the balls preferably having a cross-section such that its maximum dimension is not more than twice its minimum dimension. Polymer fibers in the shape of small, flattened discs mixed with larger cylindrical shapes (referred to as tails) can also be useful in the present method and are included in the definition of fiberball. There are a variety of methods for preparing the fiberballs of the present invention including by agitating, rolling, and/or tumbling. Crimped fibers interlock to form very low density fiberballs having an essentially permanent structure. A preferred fiberball is formed in accordance with the processes disclosed in detail in U.S. Pat. Nos.
E. I. du Pont de Nemours and Company
Edwards N.
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