Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/02—Processes; Apparatus
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/08—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests containing solids as carriers or diluents
  • A01N25/10—Macromolecular compounds
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/08—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests containing solids as carriers or diluents
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/18—Vapour or smoke emitting compositions with delayed or sustained release
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/34—Organic impregnating agents

Definitions

• the present invention is a controlled release device composed of a polymer, bioactive chemical including at least one fungicide and a binding carrier, effective to prevent or retard wood decay of a wooden object that is in direct contact with soil.
• bioactive chemical including at least one fungicide and a binding carrier
• bioactive means stimulating an organism, usually in a negative way up to and including death for purposes of a deterrent .
• the decay caused by fungi is a common and an important source of deterioration of wooden objects by removal or severing of fibers which weakens the wooden object.
• the Fungal Associates. Detection, and Fumigant control of Decay in Treated southern Pine Poles. Final Report EL-2768 for EPRI Research Project 1471-1, State University of New York 1982 Although decay most frequently occurs within 50 centimeters of the ground line, any part of the pole which has a moisture content of above 20% and is in contact with oxygen can harbor decay-producing fungi.
• the secondary region of decay is the cross-tie intersection area.
• the fungi feed on wood by extending networks of minute, threadlike strands of single cells (hyphae) through the cracks in the wood.
• the hyphae secrete enzymes that dissolve the cellulose and lining in the wood, transforming them into simple chemicals that the fungi then use as food.
• decay In its incipient stages, decay is often invisible to the naked eye, but it is capable of completely destroying large volumes of wood.
• the termites, carpenter ants and other wood invading insects bore into the wood, thereby destroying its integrity and structural strength.
• the problem of invasion by pests is exacerbated by the cracking of wood upon drying. As wood dries to below about 30 percent moisture content, it shrinks.
• a more recent approach to overcoming decay of wooden utility poles is by placing a clamshell mold around the pole.
• the clamshell mold extends from about 2-3 feet above the soil surface to about 2-3 feet below the soil surface .
• a resin mixture is placed in an annulus between the clamshell mold and the utility pole wherein the resin fills cracks and is allowed to cure and harden.
• the cured resin supports the pole and retards further decay of the wood.
• a pesticide or insecticide may be injected with the resin.
• the effective lifetime of the pesticide in the resin is relatively short and is not easily renewed.
• wood cracking exposes untreated areas which are subject to decay.
• the pressure impregnation approach provides limited decay protection for a few years up to generally about 15 years. Moreover, the pressure impregnation approach cannot be applied to wooden poles already in place.
• the decay protection of poles already in place may be extended by periodic inspection and treatment, as necessary, with the fumigants, such as chloropicrin (trichloronitromethane) , VAPAM (sodium methyldithiocarbamate) a non-volatile solid which is hydrolyzed to form (methyl isocyanate) or VORLEX, a volatile liquid containing the bioactive ingredient of methyl isocyanate in conjunction with physical strengthening of the deteriorated pole.
• the fumigants such as chloropicrin (trichloronitromethane) , VAPAM (sodium methyldithiocarbamate) a non-volatile solid which is hydrolyzed to form (methyl isocyanate) or VORLEX, a volatile liquid containing the bioactive ingredient of methyl
• the treatment with fumigants generally involves drilling a hole at ground level downward and toward the center of the pole and pouring of the fumigant into the hole.
• the physical strengthening of the deteriorated pole generally involves placing reinforcing structures, such as metal sheath, concrete poured jackets, or an adjacent supporting pole.
• impregnants or fumigants may cause significant environmental problems. Also, additional impregnants and fumigants are subject to decomposition, which renders them ineffective in the long run and not cost effective in the short run.
• concentration of bioactive ingredients resulting from a single application of an impregnant or fumigant starts out well above the minimum level necessary for effectiveness, but decreases rapidly with passing time, dropping quickly below the minimum effective level.
• controlled release device refers to a substance that results in controlled and sustained release of an bioactive chemical from its surface.
• the device provides a method for the controlled release of the chemical into the surrounding environment .
• the chemical released into the environment establishes an effective zone of action.
• microcapsules there are at least three controlled release packaging systems, including microcapsules, coated granules, and chemically-bound fungicides, wherein the fungicide is chemically bound to a polymer.
• microencapsulation it is highly versatile, makes use of a variety of manufacturing techniques, and reduces the toxicity of the contained material
• microencapsulation can add significantly to the cost of the fungicide being encapsulated. Furthermore, this process has no use in protecting the other portions of the wood.
• Coated granules have a pesticide absorbed onto a matrix such as clay and then coated with cross-linked resins which helps slow the release rate. Clay loses or releases pesticide over a short period of at most a few weeks .
• Chemically-bound pesticides are made by chemically binding the pesticide to a polymer, either by being reacting the pesticide with a preformed polymer, or by attaching the pesticide to a monomer and then cross linking to form the polymer.
• the amount of pesticide chemically bound in a polymer affects the integrity, strength and properties of the polymer. Accordingly, the amount of pesticide that is chemically bound is limited to less than about 10 wt% to maintain polymer integrity.
• a Japanese patent J5 8039-601, JA-1983-03 describes an antibacterial agent placed in a hydrophillic polymer and formed into a stick or tablet that is inserted into a hole into the trunk of a tree.
• the hydrophillic polymer absorbs moisture from the tree and dissolves thereby releasing the antibacterial agent.
• This controlled release device would be inoperative in non-living dry wood. In fact, it would be inoperative in an environment of unsteady moisture exposure since overexposure to moisture would result in dissolution too quickly and under exposure to moisture would result in insufficient dissolution to release the antibacterial agent.
• This invention pertains both to protection of wooden objects in direct contact with soil from pest invasion, wooden objects including but not limited to wooden utility poles, wooden railroad ties and wooden fence posts.
• the present invention provides a device, and a method for preventing, for a prolonged period of time, the decay and the deterioration of wooden objects caused by the invasion of pests such as fungi, termites, ants, and other wood invading flora and fauna (e.g. insects) .
• the present invention is a bound friable mixture that may be placed in a polymer.
• a bound friable mixture is achieved by combining the bioactive chemical containing at least one fungicide with a binding carrier capable of binding the bioactive chemical therein or. thereto. Binding is by sorption, e.g.
• the bound friable mixture may then be added to a prepolymer (monomer or powdered polymer) to form a controlled release device for deployment.
• the resulting controlled release device is preferably in the form of a pellet or rod that is insertable into a hole in the wooden object, or in the form of a sheet that may be placed under or around a foundation.
• the device may be applied to the outside surface of the wood alone or in combination with an internally placed device.
• the controlled release device releases the pesticide at a predetermined rate to establish a biochemical barrier or exclusion zone to prevent invasion of pests for a predetermined period of time.
• a minimum effective level is maintained throughout the object, thereby eliminating problems associated with cracking of the wood.
• such devices are capable of preventing environmental and health problems caused by the unduly high concentration of the pesticide at the surface of wooden objects or in the local environment around the object.
• the pesticide and binding carrier are mixed first then placed into the pre-polymer.
• the device releases pesticide at a high rate initially and a lower, steady rate thereafter.
• This release profile assures that the wooden object becomes protected in a* relatively short period of time, and that, subsequent to reaching the minimum effective level, only the amount of pesticide necessary to replace the degraded pesticide is released.
• This release profile diminishes potential environmental and health problems of the treatment and reduces the cost of the treatment.
• the device is applied to the outside surface of the wooden object in the form of a coat containing pesticide which is released in a controlled manner.
• the coat is applied to the external surface of the wooden object and maintains the minimum effective level of pesticide at the surface of the wood and/or in the surrounding soil.
• a member which at least partially covers the surface outside is externally applied to the wood object. This member with reservoirs holding the controlled release device provides the minimum effective level of pesticide to protect the wood structure . - 9 -
• the device is placed inside the wooden object at about ground level allowing the pesticide to be carried laterally and longitudinally by molecular and gaseous diffusion and longitudinally primarily by the capillary action of the wood structure and moisture.
• FIG. 1 is a schematic representation of the comparison of concentrations of a pesticide applied in a single dose and by the process and device of the present invention to a wooden object as a function of time.
• FIG. 2 is a perspective view of a top section of a wooden telephone pole showing the location of the controlled release device constructed in accordance with the present invention.
• FIG. 3 is a perspective view of a wooden telephone pole being treated by the process of the present invention to install a pesticide-releasing device of the present invention.
• FIG. 4 is a perspective view of the wooden telephone pole of FIG. 3 showing an installed pesticide-releasing device constructed in accordance with the present invention.
• FIG. 5 is a perspective view of drilling operation in the process of installation of the pesticide-releasing device of the present invention into new wooden utility poles, showing in partial cross-section the bore for the pesticide-releasing device of the present invention. - 10 -
• FIG. 6 is a perspective view of the railroad tracks mounted on railroad ties which contain the pesticide- releasing devices constructed and installed in accordance with the present invention.
• FIG. 7 is a perspective view of the bottom of a wooden utility pole covered with a controlled pesticide release layer constructed in accordance with an embodiment of the present invention.
• FIG. 8 is a perspective view of a railroad tie whose lower surface is covered with a controlled pesticide release layer constructed in accordance with an embodiment of the present invention.
• FIG. 9 is a cross-sectional view of a wooden utility pole surrounded by a controlled-release device constructed in accordance with an embodiment of the present invention.
• a wood attacking pest controlled release device may then be formed by placing the bound friable mixture into a polymer.
• the polymer may be from a preform of a monomer or a polymer powder that is then formed into pellet, rod, strip, sheet or any suitable shape for the desired deployment of the wood attacking pest controlled release device .
• Wood attacking pests include but are not limited to microorganisms for example fungi, and/or mold; macroorganisms including insects and arachnids, for example ants, termites, beetles, spiders; and combinations thereof. - 11 -
• Decay and deterioration of wooden objects maintained in soil can be prevented for a prolonged period of time by a controlled release device which releases a pesticide at a predetermined rate into the wooden object to maintain at least a portion of such object above the pesticide concentration that can be tolerated by pesticides.
• the devices of the present invention can prevent pest infestation of wooden objects up to the expected lifetime of such objects.
• the devices of the present invention can prevent pest caused decay and deterioration of wooden utility poles for at least twenty (20) years and preferably at least fifty (50) years.
• the process of the present invention for treating wooden objects can be used on any wooden object; however, as a practical matter, it is mostly useful in treating wooden objects which are proximate soil either within soil, in contact with soil, or sufficiently near soil that pests have access to the wooden object (s) .
• the wooden objects for which the present invention is especially useful include: wooden utility poles, wooden railroad ties, wooden bridge parts, such as bridge bracings, wooden fence posts, and the like.
• wooden objects is used herein to refer to objects made of the wood, i.e., out of dead tree trunk and branches.
• the term “wooden objects” is not intended to refer to live trees.
• the device of the present invention can be installed in wooden objects which are already in the soil and in those which have not yet been placed in the soil .
• the present invention is effective in treating both the wooden objects that have been infested by pests and those which have not yet suffered from pest infestation. Preferred deployment is for the device of the present - 12 -
• the invention to be installed in the wooden object, then release the pesticide at a controlled rate into the wood.
• the device's pesticide-release rate is selected to maintain at least a portion of the wooden object at the minimum effective level.
• minimum effective level is defined to be the pesticide level which can be tolerated by pests.
• a creation of an exclusion zone which pests cannot penetrate is sufficient to protect the entire object.
• the creation of such a zone is advantageous in that less pesticide is required than if such a level was maintained throughout the whole object. Also, it often is much less expensive to install devices for creation of such zone than for treating the entire object.
• the creation of a pest barrier or exclusion zone is advantageous for ecological and human safety reasons .
• the controlled release devices of the present invention preferably have a release rate shown in FIG. 1, which is initially rapid so as to bring the pesticide concentration of the zone in the wooden object or the entire object to the desired concentration level as quickly as possible. Thereafter, the release rate is slower, preferably just sufficient to maintain the object or the selected zone of the wooden object above the minimum effective level to prevent pest infestation.
• the initial high release rate is achieved by allowing the pesticide to release from the matrix prior to inserting the device into or onto the wooden object.
• the amount of the released pesticide can be varied by the varying temperature and the amount of time for the release prior to inserting the device.
• hydrophobic polymers serve as effective pesticide release devices because they can act - 13 -
• Hydrophobicity of the pesticide containing polymer is preferably less than about 13 on either the HLB or solubility parameter scale. More preferred in a hydrophobicity less than about 10 and most preferably less than about 8. Specifically excluded are polymers that are water soluble, and/or have ionic groups (e.g.
• the present invention includes blends for example polyethylene and POLYOX wherein POLYOX is a water soluble ethylene oxide polymer.
• the bioactive pesticide is contained within the hydrophobic polymer.
• the pesticides used in the present invention depend on the anticipated pests which in turn depend on many factors, including the type of wood, the geographical location of the wooden object, and the soil in which the object is maintained. In most cases, the pesticide is selected to eliminate fungi and wood boring insects.
• the wood boring insects which cause particular problems include carpenter ants and termites (soil born or dry wood) .
• the device can incorporate a combination of pesticides, as long as such pesticides are compatible with each other or one another. If the pesticides are not compatible because of different release rates, or, for other reasons, separate devices can be used for treatment in accordance with the present - 14 -
• the presently preferred pesticide is a pyrethrin, specifically for example tefluthrin, permethrin, cypermethrin, or combinations thereof.
• Other preferred pesticides include especially fenoxycarb, and chlorpyrifos, sold under the trademark Chlorophos by Dow Chemical.
• pesticides include but are not limited to tri-chloronitromethane under the tradename Chloropicrin, a mixture of methylisothiocyanate and 1-3 dichloropropane under the tradename Vorlex, sodium N-methyl dithiocarbomate under the tradename Vapam, 2,3,5,6 - tetracholoro - 1,9 - benzoquinone under the tradename Chloronil, calcium cyanamide, biphenyl, copper naphthenate, dichlorphen, fentin hydroxide and combinations thereof.
• Preferred fungicides are biphenyl, dichlorophen, and Chloropicrin, which are water soluble and incorporable into urethane or low density polyethylene.
• the amount of polymer is preferably about 70 wt% with fungicide in an amount from about 5 wt% to about 30 wt% and a binding carrier in an amount from about 5 wt% to about 30 wt%.
• exemplary insecticides include but are not limited to isofenphos, fenvalerate, cypermethrin, permethrin, pyrethrin, fenoxycarb, tefluthrin, and combinations thereof, as well as in combination with any of the previously cited pesticides.
• Polymer selection for the controlled release device depends upon the conditions encountered, either inside the pole, or on its outer surface.
• the polymer matrices must be able to endure the seasonal variations in temperature and moisture.
• the matrices used to coat the poles must be able to withstand amplified conditions.
• the polymer utilized in the coating must meet three requirements. First, it must be bound to the wood pole - 15 -
• thermoplastic polymers capable of withstanding such conditions and providing the desired release rates for the pesticides can be classified into four groups : thermoplastic polymers, thermoset polymers, elastomeric polymer and copolymers thereof .
• low density polyethylene high density polyethylene, vinyl acetate, urethane, polyester, silicone, neoprene, and isoprene polymer and co-polymer can all be used in this invention.
• high density polyethylene is the preferred polymer, specifically polyethylene MA778000.
• pyrethroids having both low water solubility and low vapor pressures, the low vapor pressures in the range of 1 nPa to 100 mPa, including tefluthrin (80 mPa) , permethrin (45 nPA) , lambdacyhalthrin (200 nPa) , resmethrin (1.5 nPa) , deltamethrin (0.002 mPa) , cypermethrin (0.5 nPa) , cyphenothrin (0.12 mPa) and cyfluthrin (1 mPa) are preferred in combination with high density polyethylene.
• urethane specifically Urethane 2200
• Hytrel polyesters specifically Microthene 763
• Water soluble bioactive chemicals include diazinon, chlorpyrifos, fenoxycarb, tralomethrin, methyl isothiocyanate and pentachlorophenol . - 16 -
• Binding carrier includes carbon, hydroxyapatite, alumina, silicoalumina, and combinations thereof. Carbon may be in the form of activated carbon, carbon black, and combinations thereof. Carbon black is the preferred binding carrier. More specifically, Vulcan XC-72 is preferred because Vulcan XC-72 has greater adsorption capacity compared to other carbon blacks. For bioactive chemicals that are liquid at room temperature, for example diazinon (pesticide) and copper naphthanate (fungicide) , hydroxyapatite is the preferred binding carrier.
• the preferred amount of high density polythene is about 70 wt% and low vapor pressure bioactive chemicals in an amount of about 10 wt%, with the binding carrier in an amount of about 20 wt%.
• polyester, urethane the preferred amount of plastic is about 65 wt%, and water soluble bioactive chemicals of about 15 wt%, with the amount of carrier about 0 wt% to about 25 wt%.
• bioactive chemical may range from about 5 wt% to about 30 wt% and binding carrier from about 0 wt% to about 25 wt%.
• a binding carrier When a binding carrier is added, it has been found that simply adding the binding carrier to a mix of pesticide and pre-polymer results in poor formability of the controlled release device and permits evaporation of the pesticide. Accordingly, it is preferred to first mix the pesticide into the binding carrier as a bound friable mixture so that the pesticide is preferably bound either onto the surface of the binding carrier or into the bulk - 17 -
• the bound friable mixture of pesticide and binding carrier is then added to a polymer.
• the bound pesticide is retarded or prevented from evaporation during subsequent forming of the polymer.
• the pesticide is best mixed with carrier with the pesticide in a liquid form. Some pesticides are in liquid form at room temperature, and others are solid or near solid at room temperature. Accordingly, heating the pesticide may be necessary to insure a liquid form for mixing with the binding carrier.
• the solid form is preferably a powder or granular form mixed with the binding carrier.
• the pesticide may be in the form of a paste and mixed with a binding carrier.
• the controlled release device is constructed in two parts, an inner part surrounded by an outer part.
• the inner part comprises a mix of pesticide and binding carrier with the outer part a hydrophobic polymer encapsulating the inner part.
• the outer part may also contain pesticide and binding carrier that is the same or different compared to the inner part .
• the inner part preferably has about 60 wt% pesticide, 30 wt% binding carrier and 10 wt% polymer, and may range from about 5 wt% to about 70 wt% pesticide, 10 wt% to about 95 wt% binding carrier and 0 wt% to about 85 wt% polymer.
• Forms of the controlled release device include sheets, rods, pellets, and two-part constructions including inner part and outer part rods or pellets, and/or multi-laminate sheets wherein one sheet contains the pesticide or pesticide and binding carrier and another sheet is added to prevent photodegradation of the pesticide from light exposure. - 18 -
• the pesticide When the controlled release device is for insertion into the wooden object, the pesticide must be loaded into the polymer in sufficient amounts to maintain a "minimal effective level.” It is preferred to maintain the concentration in parts by weight of the polymer from about 50 to about 80, the concentration of the pesticide from about 5 to about 30, and the concentration of the binding carrier from about 5 to about 20. By so loading the polymer, the minimum effective level can be maintained for at least seven (7) years. As the concentration profile shown in Fig. 1, a polymeric controlled release device can maintain a minimal effective level of pesticide for much greater periods of time than single application methods.
• the devices of the present invention can have any physical shape. If the device is inserted inside the wooden object, it is desirable to have the device shaped to conform to the cavity. Sheets, sleeves, multiple layers, pellets, dots on geotextile, pots, pot covers, and strips are only a few of the shapes that may embody the present invention.
• the device in some cases, it is desirable to incorporate the device into the wood in a liquid or in a gel form, which may or may not solidify once it is incorporated.
• a pesticide can be incorporated into a molten polymer which can then be injected in a molten state into a cavity in the wooden object. The polymer then solidifies, creating a solid device which fits tightly in the cavity.
• the pesticide in a molten polymer may be spread on a surface or wooden object and allowed to solidify, creating a device which surrounds a portion of the wooden object as illustrated in FIG. 3.
• the device for utility poles, as illustrated in FIG.s 2-5, it is preferred to insert the device as a controlled release device near the center of the pole so that the pesticide - 19 -
• the devices of the present invention are often tubular, as generally shown in FIG.s 2-4.
• the diameter of the tubular device may be any diameter from thread size to several feet, but is preferably from about 0.5 inch to about 2 inches .
• the length may be any length but is preferably a length that does not extend beyond the wooden object. For a device inserted longitudinally in a portion of a wooden pole to be placed below grade, it is preferred that the length of the device approximately match the distance of the wooden pole extending below grade .
• FIG. 2 illustrates an embodiment of this invention. It illustrates the controlled release device 51 already inserted near the top of the utility pole 12.
• FIG. 3 shows the process of treating an already existing utility pole 11.
• the lower end of the pole 11 is being drilled by a workman using drill 40.
• a collar 30 is set about the pole 11 to stabilize it as the drill 40 is being pushed downwards into the pole 11.
• FIG. 4 illustrates the finished pole 11 of FIG. 3 with the controlled release device 50 inserted.
• FIG. 5 illustrates the drilling operation of a new utility pole 10.
• a drill 20 is used to bore a hole 30 in the pole 10 to provide a reservoir for the controlled release device.
• FIG. 6 shows railroad cross-ties 72, wherein it is preferred to insert the controlled release device 52 near the center of the tie 72.
• a preferred mode of application includes a mechanism capable of movement on - 20 -
• the mechanism may utilize a plurality of drills to bore holes into the cross-ties 72.
• the polymer is placed in contact with the external surface of the wood object .
• This embodiment provides immediate protection for the wood.
• the embodiment maintains a minimum effective level of pesticide at the surface of the wood and, if in contact with the soil, the surrounding soil.
• the concentration in part by weight of the polymer ranges from about 50 to about 80, the concentration of the pesticide from about 50 to about 80, more preferably from about 10 to about 30, and the concentration of the binding carrier from about 10 to about 20.
• the minimum effective level can be maintained for at least seven (7) years.
• FIG.s 7 and 8 describe a mode of providing external contact.
• a coat 60 is applied to pole 12 in FIG. 7.
• a coat 61 is applied to the bottom of a railroad cross-tie 70.
• These coats 60, 61 are applied in order to protect the wood structures before the pesticide inserted into the core can diffuse through the wood to reach the outer surface of the wooden object.
• the coat is able to provide an immediate minimum effective level of pesticide. Depending upon the place of application, this minimum effective level of pesticide can also be instituted in the adjacent soil or structure.
• FIG. 7 and 8 show the wood (pole 11 or cross-tie 70) being in intimate contact with the surface soil 71.
• a protective outer layer of pesticide can be applied by using a member 110 with reservoirs 120 to hold - 21 -
• the member 110 configured as a ring partially covers the wood object 130.
• the ring 110, as the applied coating, can be placed on the wood object according to user preference.
• the coating and ring embodiments of this invention have been shown by way of example and do not limit the scope of this invention.
• the pesticide may permeate the wooden object by several mechanisms. First, if a polar, water soluble, pesticide is used and the wood contains enough moisture, the pesticide is carried by the capillary action of the wood structure. Second, the pesticide having vapor pressure of about 1 mm Hg at 25°C diffuse relatively quickly through the porous molecular wood structure through gaseous diffusion. Such pesticides diffuse through from the center to the periphery of a telephone pole in about 4 to 6 months. The pesticides having vapor pressure equal to or less than about 1 diffuse more slowly, and those having vapor pressure of less than about 0.1 mm Hg do not effectively diffuse through the wood.
• the controlled release device may be positioned externally and/or internally in a variety of locations with respect to the wooden structure. If placed above ground level, the pesticide is carried laterally and longitudinally by molecular and gaseous diffusion and longitudinally by the capillary action of the wood structure and moisture. If placed at or about at ground level, a minimum effective level can also be maintained in the soil or surface surrounding the wood structure . - 22 -
• the following controlled release devices were made and tested to obtain their release rates (Table 1) .
• the devices were made as follows. All devices, except for those employing S-113 urethane, were injection molded into a thin sheet about 1/8 inch thick. The device employing S-113 urethane was case, a method typically used for thermoset polymers. All thermoplastics were formulated using sufficient amount of carbon black to carry pesticides. All thermoplastic polymers were formulated with 10 percent pesticide, 3 or 7 percent carbon black to absorb liquid pesticide and 87 to 83 percent by weight of polymer. Specifically, devices made from thermoplastic polymers and deltamethrin and lambdacyhalothrin contained 3 percent of carbon black. The devices made from the remaining pesticides and thermoplastic polymers contained 7 percent of carbon black.
• the devices made from S-113 urethane were made from a polymer mix containing 60% S- 113, 40% castor oil, and 5% of TIPA catalyst by weight.
• the polymer mix comprised 90% of the total weight of the device.
• the pesticide, deltamethrin comprised the remaining 10% of the device. No carbon black was used in this device .
• the polymer/pesticide mixture was cast into a 1/8 inch thick sheet and heated at about 60 °C for about 40 to 60 minutes to cure the cast sheet.
• Cypermethrin polyurethane 3100 0.4 ⁇ g/cm2/day polyurethane 2200 0.7 ⁇ g/cm2/day
• Permethrin polyurethane 3100 1.4 ⁇ g/cm2/day polyurethane 2200 1.3 ⁇ g/cm2/day
• Controlled release devices in the form of sheets are made having 10 wt% pesticide, 10 wt% binding carrier and 80 wt% high density polyethylene (Polyethylene MA 778-000) - 24
• Release rates are substantially decreased compared to those in Tables 1 and 2 by an additional layer, for example metallized Mylar or Saran that is added to prevent photodegradation.
• an additional layer for example metallized Mylar or Saran that is added to prevent photodegradation.
• Example 3 A device having an inner part surrounded by or encapsulated by an outer part is constructed having an -25
• the inner part contains 60 wt% pesticide and 40 wt% binding carrier.
• the outer part is high density polyethylene of a thickness of 120 mil. Release rates are shown in Table 3.
• Pesticide Release Rate Longevity Longevity ( ⁇ g/cm 2 /day) (years) (years) @ 23 °C @ 23 °C @ 35 °C
• a pellet is made having a mass of about lOOg and a surface area of about 150 cm 2 .
• the polymer is 70 wt% high density polyethylene, with 20 wt% pesticide and 10 wt% binding carrier. Release rates are shown in Table 4. Comparing Table 4 to Table 3 , it is evident that the encapsulated two-part construction provides longer life than the pellet . 26
• Pesticide Release Rate Longevity Longevity ( ⁇ g/cm 2 /day) (years) (years) @ 23 °C @ 23 °C @ 35 °C
• Bioactive Chemical Carbon Black (wt%) Release Rate ( ⁇ g/cm 2 /day) tefluthrin 0 3.13 tefluthrin 10 0.71 lambdacyhalothrin 0 1.78

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• 1998
  • 1998-02-20 WO PCT/US1998/003265 patent/WO1999042264A1/en not_active Application Discontinuation
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