Technical Field:

The field of art to which the invention pertains comprises the art of oil cleanup from waterways. Background:

Currently, nonorganic absorbent materials are used in the cleanup of oil or other contaminants spilled in the oceans and waterways. These materials are employed in several ways. One method consists of placing pieces of nonorganic material in a porous bag. Such bags are then thrown onto the surface of the water, to be retrieved later after absorbing a quantity of the contaminant.

Another method consists of deploying a sheet or mat composed of nonorganic, synthetic materials on the surface of the contaminated water, and retrieving the mat after it has absorbed a portion of the contaminant. However, synthetic mats absorb only 7 to 15 times their weight. Deployment and retrieval of such mats is typically done by a winch mounted on a boat, which might tow the mat once it has been deployed; therefore, such mats must be strong and dimensionally stable so as to avoid tearing either during deployment or retrieval. Another use for such mats is to clean

beaches contaminated by oil by pulling a mat across the beach After use, these materials are typically cleansed with a detergen or other solvent to remove as much of the oil or other contaminan as possible, and then disposed in a landfill. However, the cost o disposing nonorganic materials is high because, as availabl landfill space has been diminishing, operators of such landfill have become reluctant to allow the disposal of non-biodegradabl materials, either completely prohibiting them, or increasing th fees charged for disposal of such materials to discourage use. Thus, to minimize the costs of disposal, organic (henc biodegradable) materials are preferred.

Organic materials such as peat moss have been used. One application of peat moss for the cleanup of oil is to fill a porous boom with the material. The boom is then placed around the spilled oil, and as the contaminated water interacts with the peat moss, the oil clings to the peat moss. However, peat moss is difficult to cleanse of the waste oil before disposal. Wood chips and knep have been similarly used, but these materials have the same disadvantages as peat moss. Cotton has superior oil absorbent characteristics over the synthetic materials commonly used because cotton fibers can take oil into the body of the fiber, whereas synthetic fibers simply hold oil to their exterior surface. Cotton also has superior absorbent properties relative to the other organic materials mentioned above. However, noncomposite, unimproved cotton mats are inherently non-buoyant, dimensionally unstable, and lack strength.

Thus, for the foregoing reasons, a need exists for a buoyant, absorbent, and organic material to be used in the cleanup of spills of oil or other contaminants in water that is dimensionally stable and has sufficient strength when wet to resist tearing or deformation during deployment and retrieval, and that can also be cleansed of the contaminant before being disposed in a landfill or otherwise.

Summary of the Invention:

It is a general object of the present invention to provide an improved oil absorbent composite mat that satisfies the need for a buoyant, absorbent, organic material for use in the cleanup of spills of oil or other contaminants in water that can also be cleansed of the contaminant before being disposed in a landfill or by other means. This and other objects of the present invention are accomplished by providing a mat in accordance with the invention comprising a nonwoven laminar web composed of a natural fiber having absorbent properties and a nonwoven laminar web composed of a synthetic fibrous material having buoyant properties secured together to collectively form a composite mat. A predetermined quantity of a polymeric emulsion is applied to at least one side of the composite mat to contribute to buoyancy and flame resistance. In one embodiment, the two webs are secured together by needling.

A preferred embodiment of the present invention is comprised of a cotton fibrous laminar web, a planer surface of which is in

proximal interface with a planer surface of a synthetic web. Th synthetic web, when constructed of materials such as low density polyprophelene, has a specific gravity less than 1.0, hence contributing to the buoyancy of the mat. The cotton web and synthetic web are secured together by needling, thereby forming a composite mat. Each side of the composite mat is impregnated with a polymeric emulsion containing polyvinyl chloride, which has a specific gravity less than 1.0, thereby contributing to the buoyancy of the mat, and is inherently flame retardant. To achieve the preferred degree of buoyancy, the polymeric emulsion should penetrate each side of the mat to a depth of at least 25% of the thickness of the mat. The synthetic web, along with the entanglement of fibers resulting from the needling process, adds strength and dimensional stability to the mat hereof.

According to another embodiment of the present invention, the natural-fiber in the natural-fiber web is cotton, fibers of which contain naturally occurring oils. It is desirable to retain these oils, as they have a specific gravity less than 1.0, thereby contributing to the buoyancy of the mat when retained.

In all the above, an additional preferred feature is that the polymeric emulsion be of a flame retardant composition such as polyvinyl chloride. This characteristic greatly enhances the safety of storing the mat in large quantities until ultimately disposed of.

Combining the cotton web with a synthetic web to form a mat and impregnating both sides of the mat with a polymeric emulsion,

where the synthetic web and emulsion both have a specific gravity of less than 1, results in a mat that is buoyant (having a specific gravity of less than 1) . Thus, such embodiments exploit the superior oil absorbent properties of cotton while overcoming its inherent lack of buoyancy to accomplish the general object noted above.

While one objective of the present invention is to provide an absorbent composite mat that is buoyant, it is anticipated that other non-water related applications for the mat will become apparent. For those applications not requiring buoyancy, the present invention meets the .need for an absorbent and more environmentally safe product that can be economically disposed of. One such embodiment does not include the components required for buoyancy but includes one natural-fiber laminar web that is needle punched for dimensional stability. Another embodiment includes multiple natural-fiber webs, all secured together by needling thereby forming a mat capable of absorbing large quantities of oil. Either of the embodiments could be impregnated on at least one side with a polymeric emulsion, and preferably an emulsion that is flame retardant.

Other objects, features, and advantages of the present invention will become apparent to those skilled in the art with reference to the detailed description, appended claims, and accompanying drawings where:

Brief Description of the Drawings

Fig. 1 isometrically illustrates a preferred embodiment of th present invention;

Fig. 2 illustrates an enlarged fragmentary view of a corne elevation of the preferred embodiment of Fig. 1;

Fig. 3 illustrates application of the polymeric emulsion t the mat hereof; and

Figs. 4A and 4B are flow diagrams depicting a process fo constructing the preferred embodiment of the present inventio shown in Figs. 1 - 3.

Description of the Preferred Embodiment:

As used herein, "web" refers to a film or layer of fiber loosely interacting so as to enable friction between the fibers t hold the fibers together in a loose, air-pocketed, non-woven fil or layer. Such a "web" is typically delivered from a card o garnett, but can also be formed by air deposition.

"Garnetted web" where used herein refers to a web delivere from a garnett, which is similar to a card.

"Cross-lapped web" where used herein refers to a we consisting of layers of garnetted webs and being formed by a cross lapping machine.

Referring to the drawings, Figure 1 shows a preferre embodiment of the mat hereof generally designated 18. The length (L2) and width (LI) are not critical to the present invention, and it is anticipated that the present invention can be manufactured in many different widths and lengths depending on the ultimate

application for the product.

As shown in Figures 2 and 3, the mat comprises a single cotton fibrous laminar web (10) comprised of two cross-lapped webs (10a and 10b), each comprised of three garnetted webs (lOal- 10a3, lObl- 10b3) , and a nonwoven synthetic fibrous laminar web (12) . The synthetic web is secured to the cotton web (10) by a needling process, the needles (30) of this process displacing and intertwining the synthetic and cotton fibers leaving elongated holes (16) . To complete the composite mat (18) , the above is impregnated on both sides with a polymeric emulsion (14) , the depth of penetration (L6) of the polymeric emulsion shown by the shading in Figure 3.

Each garnetted web (such as lOal) for these purposes is comprised of open cotton fibers intertwined and layered. Three such garnetted webs are laid together to form each cross-lapped web (10a and 10b) . Each cross-lapped web traversely overlies upon the other, each with a planer surface in close proximal contact, so as to together form the single cotton fibrous laminar web (10) .

The thickness (L5, Fig. 3) of the cotton web (10) in the completed product is usually between 0.25 inches and 0.50 inches while a thickness of about 0.38 inches is preferred for the application of forming a hollow cylindrical sleeve to wrap around a cylindrical boom. The thickness of each cross-lapped web (10a and 10b) is approximate-ly the same, as is the thickness of each garnetted web thereof. The thickness of these components varies with compression during the preferred fabrication process to be

described below.

The preferred material for the cotton web of this embodimen is ginned or reginned cotton. Cotton fibers contain naturall occurring oils which typically have a specific gravity of less tha 1.0 (although cotton fibers with the oils are nonbuoyant) therefore, it is desirable to retain these oils as they contribut to the overall buoyancy of the completed mat. The cotton of th mat retains its natural oils as the temperature used in the dryin process (described below) is kept below the vaporizatio temperature of the oils. Other varieties of cotton, includin machine grade and textile grade could also be used.

The nonwoven synthetic fibrous laminar web (12) in thi preferred embodiment is comprised of synthetic fibers that ar currently marketed under a variety of trademarks such as Vante nonwoven or Cerex nonwoven. The synthetic compositio polyprophelene is the preferred composition for these purpose because it has a specific gravity of approximately .88, thereb contributing to the overall buoyancy of the completed mat. Th preferred synthetic web of polyprophelene fibers for these purposes weighs .3 ounces per square yard. The synthetic web (12) has a planer surface in close proximal interface with a planer surface of the cotton web, and is secured to the cotton web (10) by needling, which also serves to interconnect the six garnetted webs (10al-3, 10bl-2\ and which is further discussed below.

To contribute to the buoyancy of the mat, each side of the mat (18) is impregnated with a continuous uninterrupted layer of

polymeric emulsion (14) . For the desired degree of buoyancy and depending on the specific emulsion selected, the emulsion should penetrate to a depth of at least 25% of the thickness of the mat. The polymeric emulsion used in this embodiment is a polymeric emulsion containing polyvinyl chloride. The particular variety used can be generically described as a polyvinyl chloride emulsion, and is commercially available under the trademark Air Flex 4530. The preferred variety of this material for manufacturing this embodiment is an emulsion with a concentration equivalent to 50% solids plus or minus 5%. This variety of emulsion results in optimum penetration, is inherently flame resistant, and has a specific gravity of less than 1.0, thereby contributing to the desired level of buoyancy.

The optimum predetermined quantity of polymeric emulsion for the desired degree of buoyancy in the preferred embodiment is that quantity that would constitute 10 - 20% of the total weight of the composite mat. Such a quantity of polyvinyl chloride emulsion of the above described type when applied to each side of the mat results in the desired depth of penetration and contributes to the desired degree of buoyancy of the mat.

Other polymeric emulsions, and specifically, polymer resins, can be utilized such as resins containing acrylic or polyvinyl acetate. However, while these other materials also have specific gravities less than 1.0, they are not inherently flame resistant, so other flame retardant ingredients must be added to these resins to attain this desirable characteristic.

The mat as described above has sufficient buoyancy to remai afloat, when saturated with oil, for at least 72 hours. Furthermore, due to the absorbent properties of the natural fiber, cotton, this mat is able to absorb a quantity of oil at least 2 times its own weight. Synthetic fibrous materials typically onl absorb 7 to 15 times their weight.

The mat is preferably fabricated using the process shown i the flow diagram of Figures 4A and 4B. In order to increase th rate of fabrication, two identical lines can be used (Line 1 and Line 2) from the point of entry of the raw cotton (Point A) until combining the cross-lapped webs (10a and 10b) in a merged flow beginning at Line 3, Point K. Since the second line is identical to the first, it will not be discussed (as the components of Line 2 are identified in Fig. 4A by the letter "A" following the numeric designation, but are otherwise identical to their numeric counterparts in Line 1) .

Compressed masses of staple cotton are fed into (Point A) a machine (50) commonly known as a picker, which also serves as an fiber opener as it opens the masses of staple cotton to form loose, open fibers that are delivered (Point C) from the picker (50) into a hopper (60) . These fibers are then delivered from the hopper to a garnetting machine (70) , which converts the loose, open cotton fibers into a garnetted web (such as lOal, Fig. 2) , which emerges from the garnetting machine at Point E. At this point, the garnetted web is approximately 5-6 inches thick.

The garnetted web is then transported to a cross-lapper

machine (90) which forms a cross-lapped web (such as 10a, Fig. 2) consisting of three garnetted webs (10al-3, Fig. 2). The thickness of the mat is controlled by the number of garnetted webs used to form the cross-lapped web. In this preferred embodiment, three garnetted webs were selected, but other embodiments of various thicknesses could be produced by cross-lapping a greater or fewer number of garnetted webs. The means for transporting (80,100, 110,170,190) garnetted webs, cross-lapped webs, and the mat are well known and commercially available, and will not be discussed herein except where specially designed components have been added. After emerging from the cross-lapper, the cross-lapped webs of the two lines (Line 1 and Line 2) are combined via transporting means (100) at Point K to form a single cotton fibrous laminar web composed of six garnetted webs (10al-3, 10bl-3) . In fabricating this embodiment, the combining is accomplished by arranging the transporting means (100) with respect to the second cross-lapper (90A) so that the output from the second cross lapper is fed directly onto the top of the cross-lapped web from the first cross- lapper (90) . The entire cotton fibrous laminar web (10) comprising the two cross-lapped webs is then conveyed away from the cross- lapper machines towards a compression roll (120) by well known transporting means (110) .

After emerging from the compression roll, the cotton web (10) is approximately 3 inches -thick. The purpose of compressing the cotton web is to increase the density in preparation for the needling process.

After compression (Point M) the cotton web is transported to a needle loom (140), while the synthetic web (12) is concomitantly dispensed from a roll and placed in proximal interface with the bottom planer surface of the cotton web, said roll constituting part of the means for adding the synthetic web (130) . The two webs are transported into the needle loom (140) in close, proximal contact by a transporting means (135) , the close contact maintained by compression from the rollers employed in the transporting means and the friction between the two webs.

Needle looms are well known and commercially available to secure nonwoven webs by mechanically orienting, entangling, and intertwining the fibers through the webs. This process is termed in the trade as "needling" or "needle punching". In the needle loom, barbed needles are set into a needle board that punches into the webs and withdraws, leaving the fibers entangled as well as holes (16) . The size and density of the needles, and the design of the barb vary depending on the type of web. For fabricating this embodiment, a needle board having an array of needles of 73 - 114 needles per linear inch is used, the needles being of 36 gauge and 3 1/2 inches long, with barbs of type 3 barbs per apex, regular barb arrangement. Such needles are commercially available under the trademark and model Foster Needles, 36 gauge, 3 barbs/apex, 3 1/2 inches long. To avoid tearing and distorting the webs, a two step needling process is preferred where the needles are first partially inserted 95% of the total thickness of the two webs, and then, without advancing the webs, inserted again through the entire

thickness enabling the barbs to pierce the synthetic web before being withdrawn. After every two step punch, the webs are advanced, and the two steps are repeated. The rate of needle punching and the rate of advancing the webs are coordinated to provide 50-150 punches per square inch. In the needling process, compression of the webs takes place, so that the composite mat thus formed has a thickness (L3) of approximately 0.38 inches, plus or minus 0.10 inches.

After the synthetic web and cotton web are secured together by needling to form a composite mat, the mat is transported by means (150) to a spray station (160) where a polymeric emulsion (14) containing polyvinyl chloride is sprayed on the top cotton side of the mat. The rate of dispensing the emulsion and the rate of transporting the composite mat are coordinated to provide the preferred predetermined quantity of polymeric emulsion of 10-20% of the total weight of the completed composite mat, thereby impregnating the mat. This quantity was found to provide the desired depth of penetration without undue buildup of emulsion on the surface of the mat.

From the spray station and with the sprayed emulsion still in a wet state, the mat is conveyed through an oven (180) by well known transporting means (170) for drying. The drying time depends on the temperature, air flow, and orientation of the mat with respect to the air flow in a particular oven. Regardless of the type of oven used, the temperature of the mat should not exceed about 300 degrees F. so as to prevent the natural oils of the

cotton fibers from being vaporized. Typically, a drying time of about 2-3 minutes is required at 300 degrees F.

After drying, the mat is inverted by the transporting means (190) so that the synthetic web is on top before entering a spray station (200) where the synthetic side of the composite mat is sprayed with the same emulsion similarly as before and then dried similarly as before. Having been dried, the finished product, a preferred embodiment of the mat, emerges from the oven (Point Z) .

The finished mat, as described, is highly absorbent, buoyant, dimensionally stable, strong, and flame resistant. One intended application thereof is in the cleanup of oil spills on bodies of water and can be operatively achieved in several ways. For example, the mat can be cut into strips that are placed into a porous bag that is then thrown into the spill to be retrieved some time later after cleansing the contaminated water by absorbing a quantity of oil therefrom. Another method is to fashion the mat into a hollow cylindrical sleeve to wrap around a cylindrical boom, the sleeve complementing the buoyancy of the boom. The boom is then deployed around the oil spill or deployed as a barrier to the spreading of the spill. Where the sleeve interacts with the contaminated water, oil coats and is absorbed by the cotton fibers of the mat. An additional method is to deploy a large sheet of the composite mat from a vessel that then tows the sheet through oil contaminated water from which the sheet absorbs oil. Similarly, a large sheet of the composite mat can be dragged across a beach by an appropriate vehicle to clean up oil that washes ashore.

It can also be utilized as a drop cloth by engine mechanics to absorb oil spilled during engine maintenance or as a plant wipe down material. Although these two uses would not exploit the buoyant characteristics of the composite mat, the mat would have waste disposal advantages over other products currently used due to the use of organic materials in its construction.

While the discussion here and below emphasizes the cleanup of oil, it is anticipated that the mat of the present invention could be used to absorb and cleanup substances other than oil, such as solvents and other chemicals. These uses are presented only as examples and not as limitations. Other uses will become apparent to those knowledgeable in the art.

One advantage of the mat described above is that by virtue of the use of cotton it can absorb at least twenty (20) times its own weight of a high viscosity oil. By contrast, synthetic materials, such as polyesters and polyprophelene, commonly used for oil spill control only absorb seven to fifteen times their weight. Its ability to absorb a greater amount of oil is attributed to the cotton fibers that can take oil into the body of the fiber, thereby using its full structure. This contrasts with synthetic fibers used for that purpose that simply hold the oil to the outside of the fiber in much the manner of a styrofoam cup if placed in oil. Another advantage of this embodiment is that its raw material costs are low due to the use of—unprocessed staple cotton which may be unsuitable for manufacturing textiles for clothing. Such cotton is less expensive than synthetic materials currently used in other

products.

Still another advantage is that it is highly buoyant. Cotto alone has a specific gravity of 1.25, so it would sink if throw into water. Combining the cotton web with a synthetic web to for a mat and impregnating both sides of the mat with a polymeri emulsion, where the synthetic web and emulsion both have a specifi gravity of less than 1, results in a mat that is buoyant (having specific gravity of less than 1) . Thus, this preferred embodimen exploits the superior oil absorbent properties of cotton whil overcoming its inherent lack of buoyancy. This preferre embodiment can float in sea water, the mat saturated with oil, fo approximately 72 hours or more.

Yet another advantage is that it is dimensionally stable an strong due to the use of the synthetic web and the needlin process. This preferred embodiment has a ball burst strength of 75 lbs. as measured by ASTM test no. D3787-80, ball burst method. Hence, whereas other materials might tear or fall apart during th deployment, towing, and retrieval of the sheets described above, the mat maintains its structural integrity under the most trying conditions.

By the polymeric emulsion containing polyvinyl chloride applied about the exterior of the mat, the mat is rendered flame resistant. The embodiment described is able to pass Federal Motor Vehicle Safety Standard ("FMVSS") No. 302, also known in the industry as a horizontal burn test.

Once contaminated, the preferred embodiment can be cleansed of

the oil, whereas cleansing of other organic materials such as peat moss or wood chips is uneconomical if not impossible. Furthermore, this mat has the advantage over wholly synthetic mats as it can be disposed in most landfills due to its almost entirely organic construction, whereas many landfills will not accept products composed mostly of synthetic materials. Even where incineration is the desired method of disposal, the composite mat described above, being organic, produces less toxic and fewer hydrocarbon emissions than the synthetic materials currently used for oil cleanup.

Other advantages of the preferred embodiment described above will become apparent to those knowledgeable in the art.

Variations of the present invention could be fabricated using one or multiple laminar webs composed of a natural fiber having oil absorbent properties. The embodiment using a single natural-fiber web would be needle punched for dimensional stability. In another embodiment, the multiple webs would be secured together in a superposed selection by needling. These embodiments could be fabricated in the manner described above, except that the means for adding the synthetic fibrous laminar web (130) would be eliminated, as would the spray stations (160 and 200) , and the oven (180) . Such product variations would be suitable for use as drop cloths or plant wipe down materials, and would share the preferred embodiments's advantages of low raw material cost, economical waste disposal, and high absorbency, but would lack the strength and buoyancy of the preferred embodiment described above.

Where flame resistance would continue to be desirable,

additional variations of the embodiments just described could b made by impregnating at least one side of the mat with a polymeri emulsion such as the one described in the preferred embodiment. These embodiments could be fabricated in the same way as th preferred embodiment, except that the synthetic fibrous laminar we would not be included.

Still another variation of the present invention could b constructed of wool or hemp instead of cotton. These embodiments could be manufactured just as the embodiments described above, except that these fibers would be substituted for the cotton. These embodiments being organic, hence biodegradable, would be improvements over synthetic materials currently used; however, cotton is more absorbent and, currently, less costly.

Additional embodiments could be constructed by eliminating the needling process, and utilizing other means for securing the nonwoven synthetic fibrous laminar web to the nonwoven natural- fiber laminar web.

Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment or other embodiments described herein.