ROOT-GROWTH-INHIBITING SHEET

Abstract: A sheet material (2) is disclosed which can be buried in the soil to prevent the entry of roots into unwanted regions. The sheet is a water-permeable material which holds a plurality of polymer bodies (4) containing an effective ingredient of 2,6-dinitroaniline. The effective ingredient slowly diffuses from the polymer into the soil adjacent the sheet material to prevent the root growth over time.

Description: ROOT-GROWTH-INHIBITING SHEET Introduction U.S. Patent applications Serial Number 555,113 filed November 23, 1983 and Serial Numbers 314,809 and 314,810, both filed October 26, 1981 disclose method and articles for the inhibition of root growth, partic¬ ularly the exclusion of the roots from areas in which they are undesirable, e.g., waste burial sites, under¬ ground pipelines, basements, sidewalks, or simply the boundaries between adjacent properties. The articles are formed of polymers, e.g., polyethylene, contain in admixture dinitroanilines, preferably N,N-di-n-propyl-4 trifluoromethyl 2,6-dinitroaniline having the generic name trifluralin. Among the articles which are disclosed are pellets of cylindrical form, about 9 mm in diameter and the same in length. These pellets are preferably distributed about 1 or 2 inches apart over the area which it is desired to protect. These pellets containing about 25 percent by weight of trifluralin have proven very satisfactory in use and have been shown by tests to have a probable effective life of 50 to over 100 years. Their disadvantage lies in the fact that to distribute them uniformly is a slow, laborious operation. Summary of the Invention In accordance with this invention, a porous sheet material is provided at intervals with bodies of a polymer which contain a 2,6-dinitroaniline. The sheet material is made porous to permit free passage of water. It may be either a perforated sheet or a woven or nonwoven textile material. A particularly desirable embodiment is a nonwoven fabric of non-biodegradable material. This type of material is known as a "geotextile" and is used for weed control. prevention of erosion on slopes, and other landscaping purposes. In order to obtain a root repelling property, a dinitroaniline is blended with a polymer which is attached to the geotextile or other porous material. The polymer containing the root repellent dinitro¬ aniline may be distributed in various forms, e.g., as buttons or as, continuous other elongated beads. The choice of the specific mode of distribution depends to a large part on the life desired for the root repellency. The effectiveness of the porous sheet barrier in inhibiting root elongation is controlled by the soil concentration of dinitroaniline adjacent to the barrier. This is regulated by the release rate of the dinitro- aniline from the buttons, or beads. For buttons, spacing is generally on 1- to 2-inch centers. Elongated beads are arranged in regular patterns or spacing to produce a protective soil area. The dinitroaniline will slowly diffuse from the polymer with which it is mixed at a controlled rate, be absorbed to the soil adjacent to the barrier, and thus prevent further elongation or penetration of the roots. Brief Description of the Drawings In the drawings Figure 1 is a perspective view of the embodiment employing small buttons of polymer. Figure 2 is a cross section on the line 2-2 of Figure 1. Figure 3 is a plan view of the type employing contin¬ uous beads. Figure 4 is a section on the line 4-4 of Figure 3. Detailed Description In Figure 1 we have shown a sheet of nonwoven fabric formed of felted fibers of polyethylene or other thermoplastic material. Attached to it are buttons of polymer in which is mixed from 2 to 30 dinitroaniline, preferably trifluralin. Carbon black is usually added to improve retention of the dinitroaniline. The buttons may be made from a polymer selected from the following list: Polyethylenes (low density, linear low density, high density) Polypropylene Copolymers and blends of above polymers Ethylene vinylacetate/ethylene acrylic acid/ethylene ethyl acrylate Polybutylene Acrylate-styrene-acrylonitrile Epoxies Polyamides Polyesters (aromatic) Polyurethanes Silicones Thermoplastic elastomers which may be prepared from a number of monomers such as styrene block copolymers with butadiene or isoprehe, polyether-esters or olefinics. The buttons, 4, are attached to the sheet, 2, by e.g.., adhesives or mechanical fasteners. A partic¬ ularly desirable mode is by extrusion of a molten plastic mixed with the dinitroaniline onto or through the fabric and allowing it to cool in place. Desirably the buttons have an average diameter of 1/4 to 3/8 inch and an average thickness of 1/8 to 3/8 inch and spaced on 1 to 3 inch centers, preferably not more than 2 inches. As stated above, they should contain from 2 to 30 percent dinitro¬ aniline. Based on experimental results, buttons of the 3/8-inch diameter and 3/8-inch thickness containing 25 percent trifluralin and 25 percent carbon black will have an effective root repelling lifetime of at least 50 years and probably 100 years. Buttons of other sizes made of different polymers and/or containing different dinitroanilines will have different lives which may be varied according to the intended use. As may be expected, the use of smaller buttons and the use of smaller proportions of dinitroaniline will result in shorter lives, as will the use of dinitroanilines which diffuse more rapidly than trifluralin. While we have shown the buttons arranged in right angled rows, other distributions, e.g., in a diamond pattern, may be preferred in some cases. In Figures 3 and 4 we show the use of elongated beads, 8, attached to the fabric 6. These beads may be formed of the same materials and attached in the same manner as the buttons, .4, of Figures 1 and 2. They may have widths and thicknesses in the range of 1/16 to 1/4 inch and should not leave gaps of more than 2 inches. Because they have a stiffening effect on the fabric, this embodiment is somewhat less flexible in use than the one having buttons shown in Figures 1 and 2. The beads need not be parallel, but may be arranged in other patterns. While we have described certain embodiments • in detail, it will be obvious to those skilled in " the art that various changes can be made. We therefore wish our invention to be limited solely by the scope of the appended claims.

Claims: The embodiments of the invention in which a proprietary right or privilege is claimed are defined as follows: 1. A material for preventing the entry of roots 05 into unwanted areas comprising a sheet of water-permeable material carrying distributed bodies of a polymer contain¬ ing from 2 to 25 percent of a 2,6-dinitroaniline. 2. A material as defined in claim 1 wherein said dinitroaniline is trifluralin. 10 3. A material as defined in claim 1 wherein said sheet material is flexible. 4. A material as defined in claim 2 wherein said sheet material is flexible. 5. A material as defined in claim 1 wherein 15 said sheet material is of a non-biodegradable composition. 6. A material as defined in claim 2 wherein said sheet material is of a non-biodegradable composition. 7. A material as defined in claim 1 wherein said sheet is a nonwoven fabric of a non-biodegradable 20 polymeric composition. 8. Material as defined in claim 2 wherein said sheet is formed of nonwoven fabric of a non-biodegradable polymeric composition. 9. Material as defined in claim 1 wherein said 25 polymer is in the form of buttons attached to and distrib¬ uted over said sheet. 10. Material as defined in claim 2 wherein said polymer is in the form of buttons distributed over said sheet. 30 11. Material as defined in claim 10 wherein said . polymer is polyethylene. 12. A material as defined in claim 11 wherein said buttons are of polyethylene containing trifluralin and carbon. 13. Material as defined in claim 12 wherein said buttons are 1/4 to 3/8 inch in diameter and 1/8 to 3/8 inch maximum thickness. 14. Material as defined in claim 13 wherein said buttons are spaced apart an average of 1 to 3 inches. 15. A material as defined in claim 1 wherein said polymer is in the form of elongated beads. 16. Material as defined in claim 15 wherein said beads are of polyethylene. 17. Material as defined in claim 16 wherein said beads contain 2 to 30 percent trifluralin. 18. Material as defined in claim 17 wherein said polyethylene also contains carbon black. 19. Material as defined in claim 18 wherein said beads are 1/16 to 1/4 inch wide and from 1/16 to 1/4 inch in maximum thickness.

Inventors: BURTON FREDERICK G, CATALDO DOMINIC A, CLINE JOHN F, SKIENS W EUGENE, VAN VORIS PETER, BURTON, FREDERICK, G., CATALDO, DOMINIC, A., CLINE, JOHN, F., SKIENS, W., EUGENE, VAN VORIS, PETER
Applicants: BATTELLE MEMORIAL INSTITUTE
Application year: 1988
Main classification: A01G13
IPC codes: A01G13