WO2000011930A1

WO2000011930A1 - Multi-layered biocide-containing covering for agricultural cultivation and related methods

Info

Publication number: WO2000011930A1
Application number: PCT/US1999/019901
Authority: WO
Inventors: Ihab M. Hekal
Original assignee: Capitol Vial, Inc.
Priority date: 1998-08-31
Filing date: 1999-08-31
Publication date: 2000-03-09
Also published as: WO2000011930A9; AU5796199A

Abstract

A multi-layered biocide-covering plastic covering (1) for an agricultural cultivation (2) comprising upper (10) and lower (20) layers of plastic, a layer (30) containing a biocide sandwiched between the upper (10) and lower (20) layers of plastic whereby a user would lay the covering (1) over a plant bed, puncture one or more apertures (40) through the covering (1), plant the agricultural cultivation (2) within one or more of the apertures (40) and allow the one or more agricultural cultivation (2) to grow through the aperture (40), and release biocide from the biocide-containing layer (30) of the covering (1) to the agricultural cultivation (2) to protect the agricultural cultivation (2) from infesting pests and parasites. The biocide-containing layer (30) can have channels formed by channeling agents wherein the biocide is entrained and related methods are also provided.

Description

MULTI-LAYERED BIOCIDE-CONTAINING COVERING FOR AGRICULTURAL CULTIVATION AND RELATED METHODS

RELATED APPLICATION This application is a continuation-in-part of U.S. Serial No. 09/087,824, filed May 29,

1998, which is a continuation-in-part of U.S. Serial 08/812,315, filed March 5, 1997, which in turn is a continuation-in-part of U.S., Serial No. 08/611,298, filed on March 5, 1996, which in turn is a continuation-in-part of U.S. Serial No. 08/424,996, filed April 1995. FIELD OF THE INVENTION The present invention relates to a multi-layered biocide-containing plastic covering for agricultural cultivations and related methods of manufacture. The present invention also relates to a process for covering and protecting agricultural cultivations from infesting pests and surrounding weeds. BACKGROUND OF THE INVENTION In agriculture, a thin flexible plastic film or sheet may be placed on the ground overlaying elongated seed beds. An opening in the plastic is provided so that the plated crop has its stems protruding through the opening in the plastic. Consequently, the ground surrounding the base of the plant stem is covered with the plastic sheet. In addition, the plastic sheet minimizes the growth of weeds by either being opaque, thereby denying sunlight to surrounding weeds so that they will not flourish, or clear, in which case the weeds cannot push up through the plastic so that they will wither and die. A further advantage of laying plastic sheets over crop plants is that water evaporation from the soil is minimized, leaving the water entrapped in the soil for the benefit of the plant itself.

Such coverings, however, have the disadvantage of protecting not only the useful cultivation but also parasites and infesting insects. Moreover, the large amount of moisture which forms on the inside of the covering and in the interspace between the covering and the soil, may promote the growth of poisonous fungi. Such drawbacks are obviated by applying pesticide directly to the soil both before the covering is put in place as well as during the period in which the cultivation is to be protected. In the case where the pesticides are applied to the soil before the covering is put in place, there is typically a heavy dispersion of the pesticides, inasmuch as only a minimal part of the pesticide reaches the prefixed "target" in a useful stretch of time in order to obtain the desired effect. In the second case, if the dimensions of the covering do not allow access to the cultivations, it is necessary to uncover the cultivations each time by a manual operation or, if the space does allow it, it is necessary to carry out the applications underneath the cover, with all the consequential risks of intoxication for the operating land worker. SUMMARY OF THE INVENTION The present invention relates to a multi-layered biocide-containing plastic covering comprising: (a) at least one upper layer of plastic; (b) at least one lower layer of plastic; and (c) at least one layer containing a biocide sandwiched between the upper and lower layer of plastic. In one embodiment a user would lay the covering over an agricultural cultivation bed, puncture one or more apertures throughout the covering, plant agricultural cultivations within one or more of the apertures, allow the agricultural cultivation to grow through one or more of the apertures and allow the biocide to be emitted from the covering to the agricultural cultivation thereby protecting the agricultural cultivations from infesting pests and parasites.

In another embodiment, the covering can comprise one or more apertures for planting agricultural cultivation within one or more of the apertures and allowing the agricultural cultivation to grow through each of the apertures.

In a further embodiment, the upper layer of plastic can be composed of an opaque material so as to prevent the penetration of sunlight and thus, reduce or eliminate the growth of weeds. The lower layer of plastic can be composed of a liquid impermeable material to prevent the leeching of biocide into the ground. In yet another embodiment, the upper and lower layers of plastic are composed of a liquid impermeable material.

In another embodiment, the biocide is entrained in a polymer where channels are established throughout the polymer matrix that are capable of controlled transmission through the polymer matrix. The channels communicate the entrained biocide to the appropriate areas of the exterior of the polymer shaped article in a manner that permits the desired property to migrate from the interior locations where the biocide is positioned to the outside of the polymer structure. Furthermore, these channels through which the desired property is permitted to travel are occupied by channeling agents that control the transmission rate into the polymer. The channeling agents are used to act as bridges from the surface of the plastic bodies inwardly to the biocide positioned within the plastic structure. Suitable channeling agents include polyglycols including polyethylene glycol, ethylene vinyl alcohol (EVOH), polyvinyl alcohol

(PVOH) and glycerin. In still another embodiment, the biocide may also include herbicides, pesticides, fungicides, rodenticides and/or mixtures thereof. In yet another embodiment, the biocide may have a sufficient vapor pressure whereby the biocide is continually released after the user punctures one or more apertures in the covering. In one embodiment, the biocide may be encapsulated between the upper and lower layers of plastic. In a further embodiment, the biocide may be laminated on either the upper layer or lower layer of plastic. In still a further embodiment, the biocide may be entrained within the channels of the biocide-containing layer. In addition to the biocide, the covering may also contain other compositions including release nutrients, plant growth regulations, pheromones, defoliants and/or mixture thereof.

In one embodiment, the present invention also relates to a method of covering and protecting agricultural cultivation. The method comprises the steps of: (a) providing a covering comprising at least one upper layer of plastic, at least one lower of plastic and at least one layer containing a biocide sandwiched between the upper and lower layers of plastic; (b) laying the covering over an agricultural cultivations bed; (c) puncturing one or more apertures throughout the covering; (d) planting agricultural cultivations within one or more of the apertures and allowing the agricultural cultivation to grow through one or more of the apertures; and (e) allowing the biocide to emit from the covering to the agricultural cultivation thereby protecting the agricultural cultivation from infesting pests and parasites. In one embodiment, the step of puncturing one or more apertures into the covering is performed prior to laying the covering over the agricultural cultivation bed. The method may also include encapsulating the biocide between the upper and lower layers of plastic. In another embodiment, the biocide can be laminated on either the upper layer or lower layer of plastic before the sandwiching step. In another embodiment, the present invention also relates to a method of manufacturing a multi-layered biocide-containing covering for agricultural cultivation. The method comprises the steps of providing at least one upper layer of plastic and at least one lower layer of plastic and sandwiching at least one layer containing a biocide between the upper and lower layers of plastic for the covering. In a further embodiment, the method may further comprise the steps of encapsulating the biocide between the upper and lower layer of plastic. In another embodiment, the biocide is laminated on either the upper layer or the lower layer of plastic. In still a further embodiment, the method also comprises the step of forming channels within the biocide-containing layer and entraining biocide within the channels. In yet another embodiment, the method further comprises forming channels within the biocide-containing layer utilizing channeling agents such as polyglycols including polyethylene glycol, ethylene vinyl alcohol and glycerin. The covering of the present invention can be extruded or cut into sheets or strips of plastic material.

In yet a further embodiment, the present invention relates to a method of fixing the biocide and releasing the biocide in the presence of water with the assistance of a catalyst. In such an embodiment, the biocide may contain a hydroxyl group and the polymer may contain a maleic anyhdride group. The two groups are reacted and fixed to form an ester. The catalyst may be an acid group such as a sulfanate group. In the presence of water, the catalyst (i.e. sulfanate group) will hydrolyze the esters thereby resulting in the release of the maleic anhydride group and the biocide.

In still a further embodiment, the outer layer of the covering of the present invention may be coated with a fungicide. If fungicide reacts with the biocide, the fungicide may be coextruded with an extra layer of an inert plastic between the fungicide and biocide layer. In still another embodiment, the covering of the present invention may be cut into strips, collars, or sleeves which may be directly placed around the stems of the agricultural cultivations. The collar-type covering may include a closing mechanism such as a velcro to secure the covering around the stems of the agricultural cultivations. In still yet a further embodiment, the covering may have a multitude of layers including a multitude of biocide-covering layers. In such an embodiment, each biocide-containing layer has a different and specific biocide to target a specific insect or pest. In another embodiment, the lower layer of the covering may contain a fertilizer such as a nitrogen fixing bacteria. Upon placing the covering over the agricultural cultivation bed, the fertilizer would have direct contact with the soil.

In still another embodiment, the present invention relates to a covering having factory- made slits or semicircular apertures to which seeds or seedlings are adhered to the slits or apertures. The adhesive may be a water soluble adhesive. In the presence of water, the seeds would be separated from the slits or apertures and fall into the soil. During growth, the agricultural cultivations would pierce through the slits or apertures. In another embodiment, additives such as nutrients may be also adhered to the slits or apertures and thereby be released in the presence of water. BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily understood by reference to the following description when considered in connection with the accompanying drawings in which: FIGURE 1 is a perspective view of the multi-layered biocide-containing plastic covering of the presently claimed invention.

FIGURE 2 is a cross-sectional view of the invention particularly focusing on the three layers of the covering including upper and lower layers of plastic and a layer containing a biocide sandwich between the upper and lower layers of plastic. FIGURE 3 is a cross-sectional view of the covering having a biocide-containing layer with a channeling agent and a biocide blended therewith.

FIGURE 4 is a cross-sectional view of the covering in relation to an agricultural cultivation. Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 whereon the multi-layered biocide-containing covering 1 of the present invention is illustrated. The covering 1 comprises at least one upper layer of plastic 10 and at least one lower layer of plastic 20. A layer 30 containing a biocide is sandwiched between the upper and lower layers of plastic, 10 and 20 respectively. A user of the covering 1 would lay the covering over an agricultural cultivation bed, and puncture one or more apertures 40 throughout the covering 1. The user may then plant an agricultural cultivation 2 within one of the apertures 40 and allow the agricultural cultivation 2 to grow through the aperture 40. Upon puncturing of the aperture 40, the biocide from the biocide-containing layer 30 will be emitted from the covering 1 and protect the agricultural cultivation 2 from infesting pests and parasites. In one embodiment, the coverings should be as wide as a agricultural cultivation bed plus the slanted side of each furrow on each side of the bed and the trough of the furrow. Now since water is directed to the crops by irrigation methods of running the water into the furrows, the coverings may be no wider than the agricultural cultivation bed (together with one side wall and bottom of each oppositely situated furrow) unless measures are taken to cut the coverings at the bottom of the furrow, or to make perforations through it at that point. It is necessary for the irrigation water in the furrow to seep into the ground and if the coverings are continuous in lining the furrow, no water will penetrate. In many cases, the coverings may be from 2 to 4 or 5 feet in width depending upon the bed. The beds may vary in length from a few hundred feet to thousands to feet.

The term "multi-layered" is defined as having two or more layers of covering. Agricultural cultivation refers to plants, flowers, herbs, and any other agricultural, botanical and horticultural organism.

The plastics that are suitable for the upper and lower layers of the covering 1 of the present invention, include but are not limited to, thermoplastics or thermosets. Thermoplastics consists of long chain molecules. Examples of suitable thermoplastic materials include polyolefins such as polypropylene and polyethylene, polycarbonates, polyamides, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymer, poly vinyl chloride, polystyrene, polyester, polyester amide, polyacrylic ester, acrylic, polyurethane and polyacetal, or mixtures thereof. Thermoset plastics contain infinite three dimensional networks. Examples of thermosets include epoxy polyurethene and polyester.

The biocides of the present invention may include, but are not limited to, pesticides, herbicides, fungicides, rodenticides and/or mixtures thereof. In addition to the biocides, the covering of the present invention can also release nutrients, plant growth regulators, pheromones, defoliants and/or mixture thereof. The pesticides useful in the concentrated and finished products of the present invention may include one or more of the following: 1,2- Dichloropropane; 1-Naphthaleneacetamide; l-Naphthylacetic_Acid; 2,4,5-T_Acid; 2,4,5- T_Amine_Salts; 2,4,5-TJEsters; 2,4-D-Acid; 2,4-Db_Butoxyethyl_Ester; 2,4-

DbJDimethylamine; Abamectin; Acephate; Acifluoren_Sodium_Salt; Acrolein; Alachlor; Aldicarb; Aldoxycarb; Aldrin; Ametryn; Aminocarb; Amitraz; Amitrole; Ancymidol; Anilazine; Arsenic_Acid; Asulam,Sodium; Atrazine; Azinphos-Me; Barban; Benalaxyl; Bendiocarb; Benefϊn; Benodanil; Benomyl; Bensulfuron Me; Bensulide; Bentazon_Sodium_Salt; Bifenox; Bifenthrin; Bromacil; Bromoxynil_Butyrate; Bromoxynil_Octanoate; Butachlor; Butylate;

Captafol; Captan; Carbaryl; Carbendazim; Carbofuran; Carbon_Disulfide; Carbophenothion; Carboxin; Cdaa; Chloramben; Chlorbromuron; Chlordane; Chlordimeform; Chlordimeform_Hcl; Chlorfenac_Sodium_Salt; Chloridazon; Chlorimuron_Et;

Chlorobenzilate; Chloroneb; Chloropicrin; Chlorothalonil; Chloroxuron; Chlorpropham;

Chlorpyrifos; Chlorpyrifos-Methyl; Chlorsulfuron; Chlozolinate; Cinmethylin; Clofentezine;

Clomazone; Clopyralid; Cryolite; Cyanazine; Cycloate; Cyfluthrin; Cyhalothrin; Cyhexatin; Cypermethrin; Cyromazine; Dalapon_Sodium_Salt; Daminozide; Dazomet; Dbcp;

Dcna Dicloran; Dcpa_Chlorthal-Dimethyl; dd; Dde; Ddt; Demeton; Desmedipham; Di-Allate;

Diazinon; Dicamba; Dichlobenil; Dichlone; Dichlormid; Dichloropropene; Dichlorprop;

Dichlorvos; Diclofop-Me; Dicofol; Dicrotophos; Dieldrin; Dienochlor; Diethatyl-Et;

Difenzoquat_Me-Sulfate_Salt; Diflubenzuron; Dimethipin; Dimethirimol; Dimethoate; Dimethylarsinic Acid; Dinitramine; Dinocap; Dinoseb; Dioxacarb; Dipropetryn;

Diquat_Dibromide; Disulfoton; Diuron; Dnoc; Dodine_Acetate_Salt; Dsma; Endosulfan;

Endothall; Endrin; Epn; Eptc; Esfenvalerate; Ethalfluralin; Ethephon; Ethofumesate; Ethoprop;

Ethylene_Dibromide; Etridiazole; Fenaminosulf; Fenamiphos; Fenarimol; Fenbutatin_Oxide;

Fenfuram; Fenitrothion; Fenoprop; Fenoxaprop-Et; Fenoxycarb; Fenpropathrin; Fensulfothion; Fenthion; Fenuron; Fenvalerate; Ferbam; Fluazifop-Butyl; Fluazifop-P-Butyl; Fluchloralin;

Flucythrinate; Flumetralin; Flumetsulam; Fluometuron; Fluridone; Fomesafen; Fonofos;

Formetanate_Hcl; Fosamine Ammonium; Fosetyl Aluminum; Glufosinate- Ammonium;

Glyphosate; Haloxyfop-Methyl; Heptachlor; Hexachlorobenzene; Hexazinone;

Hydramethylnon; Imazalil; Imazamethabenz-Me_P-Isomer; Imazapyr_Acid; Imazapyr_Isopropylamine_Salt; Imazaquin- Ammonium; Imazaquin_Acid; Imazethapyr;

Iprodione; Isazofos; Isofenphos; Isopropalin; Isoxaben; Lactofen; Lindane; Linuron; Malathion;

Maleic_Hydrazide_Acid; Maleic_Hydrazide_K_Salt; Mancozeb; Maneb; Mcpa; Mcpb;

Mecoprop; Mefluidide; Mepiquat_Chloride; Metalaxyl; Metaldehyde; Methamidophos;

Metham_Sodium; Methazole; Methiocarb; Methomyl; Methoxychlor; MethylJBrornide; Methyl_Isothiocyanate; Methyl Parathion; Metiram; Metolachlor; Metribuzin;

MetsulfuronJVle; Mevinphos; Mexacarbate; Mirex; Molinate; Monocrotophos; Monolinuron; Monuron; Msma; Myclobutanil; Naled; Naphthalene; Napropamide; Naptalam_Sodium_Salt; Neburon; Nicosulfuron; Nitrapyrin; Nitrogen; Norflurazon; Oryzalin; Oxadiazon; Oxamyl; Oxycarboxin; Oxydemeton-Me; Oxyfluorfen; Paclobutrazol; Paraquat Dichloride; Parathion; Pebulate; Pendimethalin; Pentachlorophenol; Perfluidone; Perimiphos-Ethyl; Permethrin;

Phenmedipham; Phenthoate; Phorate; Phosalone; Phosmet; Phosphamidon; Picloram; Piperalin; Pirimicarb; Pirimiphos-Me; Primisulfuron-Methyl; Prochloraz; Procymidone; Prodiamine; Profenofos; Profluralin; Promecarb; Prometon; Prometryn; Propachlor; Propamocarb Hcl; Propanil; Propargite; Propazine; Propham; Propiconazole; Propoxur; Propyzamide; Pyrethrins; Quinomethionate; Quintozene; Quizalofop-Et; Resmethrin; Rotenone; Secbumeton; Sethoxydim; Siduron; Simazine; Simetryn; Sodium_Chlorate; Sulfometuron-Me; Sulprofos; Tau-Fluvalinate; Tea-Sodium; Tebuthiuron; Temephos; Terbacil; Terbufos; Terbutryn;

Tetrachlorvinphos; Thiabendazole; Thidiazuron; Thifensulfuron_Me; Thiobencarb; Thiocyclam- Hydrogen_Oxalate; Thiodicarb; Thiophanate-Me; Thiram; Tolclofos-Methyl; Toxaphene; Tralomethrin; Triadimefon; Triadimenol; Triallate; Triasulfuron; Tribenuron-Me; Tribufos; Trichlorfon; Trichloronat; Triclopyr; Tricyclazole; Tridiphane; Triflumizole; Trifluralin; Triforine; Trimethacarb; Vinclozolin; Zineb; Ziram.

The types of biocides, the quantity of biocide and/or the concentration of biocide are chosen based on numerous factors including: the required vapor pressure; the required potency; the target (e.g. what types of pests and parasites a user desires to kill or rid of); the agricultural cultivation types (e.g. what type of plant is being protected); ecological effects; health effects; handleability and storage, temperature, duration of efficacy, etc. In one embodiment, the type of biocide is selected that has excellent plasticizing agents as well as superior soil and systematic pesticides. In another embodiment, the biocides are highly effective for controlling soil borne insects and nematodes which attack the root systems of plants. Suitable biocides are chosen since they are effective for controlling chewing and puncturing insects and arachnids which feed on the foliage or fluids of plants.

FIG 2 depicts a cross-sectioned view of the covering 1 of the present invention. The biocide-containing layer 30 is sandwiched between the upper and lower layer of plastics, 10 and 20 respectively. In one embodiment, the upper layer 10 and lower layer 20 are in contact with each other and overlap to thereby encapsulates the biocide-containing layer 30. In one embodiment, the biocides may be encapsulated between the upper and lower layer of plastic 10 and 20 or may be laminated on either the upper or lower side of plastic. Spreading of the biocides such as pesticides may be carried out either on the whole surface of the film or on only part of it in the form of strips or "spots". The biocides may be applied either while producing the film itself or "on the field" by using suitable equipment and employing suitable formulations of biocides or pesticides.

In yet another embodiment, solutions of the biocides may be deposited by spreading, brushing, by means of dosing devices, motor pumps or distributors, atomizers in the presence of suitable propellants or in a current of air or other gas. In a further embodiment, emulsions may be used by diluting with water solutions of the biocides in hydrosoluble solvents in the presence of surfactants, in suitable homogenizers.

In another embodiment, the biocides such as pesticides may be applied by dispersing them homogeneously in spreadable pastes or in hydropermeable varnishes, and to then applying such pastes or varnishes on the surface of the film turned towards the cultivation. If liquid products are involved, they can be spread as such, in the presence or absence of wetting agents, dispersants and surfactants.

FIG. 3 illustrates a cross-sectional view of the covering having upper and lower layers of plastic, 10 and 20 respectively, and a biocide-containing layer 30 with a channeling agent and a biocide blended therewith sandwiched between the upper and lower layers of plastic. For purposes of this disclosure of the present invention, the words "entrain", "contain", and "blend" have been used interchangeably when referring to the inclusion of the biocide 40 in a polymer 25 matrix. Veins or channels 45 are formed throughout the polymeric composition to establish passages throughout the solidified plug 55. The passages terminate in channel openings 48 at an exterior surface of the composition 55.

In the embodiment where the biocide is entrained in a polymer layer, it has been discovered that certain compounds, which are referred to herein as channeling agents, may be combined with a polymer base matrix that is used in the formation of shaped articles. In one embodiment of utilizing the channeling agent, the biocide and channeling agent are added to the polymer when the polymer base is in a molten state or before the polymer is in the molten state, so that the biocide and channeling agent may be blended and thoroughly mixed throughout the base polymer material to insure that all of the materials are thoroughly mixed before reaching the melt phase. For example, such a technique is useful when the biocide, channeling agent and polymer base are all powders. Alternatively, the channeling agent and polymer may be mixed prior to adding the biocide. The channeling agent is added either before the polymer is in the molten state or after the polymer is in the molten state. For example, the biocide may be added to the polymer base during the thermal forming process of sheets of plastic material. After thoroughly blending the materials together in the molten state, the channeling agent forms veins or channels that act as transmission communicating passages throughout the polymer. Suitable channeling agents include polyglycol such as polyethylene glycol, ethylene- vinyl alcohol (EVOH) and polyvinyl alcohol (PVOH) and glycerin. The polymer base and channeling agents do not separate out into distinct levels or phases, one above the other, but instead it is believed establish veined domains of channeling agent that extend across the polymer base thereby establishing channels or passages through the polymer. The channels are open at the surface of the polymer structures and thereby provide access for the desired property to exterior portions of the polymer matrix.

In another embodiment of utilizing the channeling agents, channeling agents may be blended and then reacted with a polymer base matrix that is used in the formation of shaped articles. In practice, the polymer base material into which the channeling agent is blended and then reacted includes, as examples, any anhydride or amine or acid or cyante or isocyanate or hydroxy functionalized polymer.

One example of blending and reacting involves, prior to reacting the channeling agent with the polymer, adding the biocide, channeling and polymer when the polymer base is in a molten state or before the polymer is in the molten state, so that the biocide and channeling agents may be blended and thoroughly mixed throughout the base polymer material to insure that all of the materials are thoroughly mixed before reacting the melt phase. For example, such a technique is useful when the biocide, channeling agent and polymer base are all powders. Alternatively, the channeling agent and polymer may be mixed and reacted prior to adding the biocide. The channeling agent would then be added either before the polymer is in the molten state or after the polymer is in the molten state. For example, the biocide may be added after the polymer base reacted with the channeling agent and during the thermal forming process of sheets of plastic material.

After thoroughly blending and reacting the materials together, the channeling agent forms veins or channels that act as transmission communicating passages throughout the polymer. Suitable channeling agents include polyglycol such as polyethylene glycol, ethylene- vinyl alcohol (EVOH), polyvinyl alcohol (PVOH), glycerin polyamine, polyurethane and polycarboxylic acid including polyacrylic acid or polymethacrylic acid. In one embodiment of the present invention, when the polymer matrix used is a polymer containing acid and/or anhydride groups, the channeling agent should be selected from the group of channeling agents including polyglycol, polyhydroxy or polyamine. In another embodiment of the present invention, when the polymer matrix used is a polymer containing amine groups, the channeling agent should be selected from the group of channeling agents including polycarboxylic acid. The result of either process utilizing the channeling agent is that the polymer base and channeling agents do not separate out into distinct levels or phases, one above the other, but instead it is believed establish veined domains of channeling agent that extend across the polymer base thereby establishing channels or passages through the polymer. The channels are open at the surface of the polymer structures and thereby provide access for the desired property to interior portions of the polymer matrix.

In general, in the embodiment where the channeling agent is blended and then reacted with the base polymer, the matrix base polymer of the present invention which can be used in making the structures of the present invention can be basically any functionalized thermoplastic including anhydride or amine or acid or cyanate or isocyanate or hydroxy functionalized polymer. Examples of suitable matrix base polymer of the present invention include polypropylene maleic anhydride, polyethylene maleic anhydride, polystyrene maleic anhydride, polyethylene acrylic acid, polyethylene-urethere, polyethylene-EVOH and polyethylene-nylon. Other suitable thermoplastic materials include grafted polyolefins, polycarbonates, polyamides, ethylene-vinyl acetate partially hydrolyzed polymers, ethylene-methacrylate partially hydrolyzed polymer, grafted polyvinyl chloride, grafted polystyrene, polyester, polyester amide, polyacrylic partially hydrolyzed ester, acrylic, polyurethane and polyacetal or mixtures thereof.

In general, in the embodiment where the channeling agent is blended with the base polymer, the matrix base polymer material of the present invention can be any thermoplastic material. Examples of suitable thermoplastic materials include polyolefins such as polypropylene and polyethylene, polycarbonates, polyamides, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymer, polyvinyl chloride, polystyrene, polyester, polyester amide, polyacrylic ester, acrylic, polyurethane and polyacetal, or mixtures thereof. For either embodiment utilizing the channeling agent, the channeling agent can generally be any hydrophilic material. In one embodiment, the hydrophilic material is a polar compound. Suitable channeling agents of the present invention include polyglycols such as polyethylene glycol and polypropylene glycol and mixtures thereof. Other suitable materials include EVOH, glycerin, pentaerithritol, PVOH, polyvinylpyrollidine, vinylpyrollidone or N- methyl pyrollidone, with polysaccharide based compounds such as glucose, fructose, and their alcohols, and mannitol being suitable for the purposes of the present invention since they are hydrophilic compounds. Suitable channeling agents of the present invention may also include any hydrophilic material wherein, during processing, the channeling agent is heated about its melt point upon melt mixing, and subsequently upon cooling separates from the polymer matrix polymer to form the channeled structure of the present invention and a two phase system. As another example, the suitable channeling agent may also include a hydrophilic material combined with a thermoplastic and the biocide and, using sufficient processing conditions, form a three phase system.

An example of utilizing the channeling agent of the present invention would include a biocide, polypropylene and polyglycol layer. The amounts of the various components would be for example, from about 0.01 wt % to about 80 wt % biocide; a minimum of about 20 wt % of the polypropylene, e.g. polypropylene homopolymer available from Exxon 3505, having a melt flow of 400, and from about 1 wt % to about 20 wt % of the polyglycol, e.g., polyethylene propylene glycol available from Dow (15-200).

For the embodiment utilizing the blending and reaction of the channeling agent, the reaction conditions between the matrix base polymer and the channeling agent are chosen to result in a complete reaction of the polymer and the channeling agent. Consequently, sufficient time and temperature are employed to result in a complete reaction of the components. As an example, the channeling agent and polymer would be first uniformly blended together. Subsequently, the mixture would be reacted at about 300°F to 350°F for about 1 to about 5 minutes. It is understood that any suitable reactor equipment may be used with the present invention including a continuous reactor such as an extruder or a batch reactor such as a continuous stirred tank reactor.

As another example, the components would be first dry mixed in a mixer such as a Henschel, and then fed to a compounder. A Leistritz twin screw extruder, for example, or a Werner Pfleider mixer can be used to achieve a good melt mix and reaction at about 300°F to about 350°F. The melt can then be either extruded to form, for example, a film or converted into pellets using dry air cooling on a vibrating conveyer. The formed pellets, containing channels, can, for example, then be either injection molded into beads, sieves, or co-injected with polypropylene as the inside layer of a container. FIG. 4 illustrates a cross-sectional view of the covering 1 and its relationship with an agricultural cultivation 2. The covering 1 lays over an agricultural cultivation bed 3. The agricultural cultivation 2 grows through the aperture 40 of the covering 1. The arrows depict the emission of a biocide 40 from the biocide-containing layer 30 which is sandwiched between the upper layer 10 and lower layer 20 of plastic to the agricultural cultivation 2.

The covering provides an essentially closed system for handling toxic and nontoxic pesticidal materials. This covering eliminates dusting problems and addresses the potential environmental pollution problems encountered in the manufacture of convention pesticidal formulations by conventional methods are avoided.

Numerous modifications and variations of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the attendant claims appended hereto, this invention may be practiced otherwise than as specifically disclosed herein.

Claims

CLAIM What Is Claimed Is:

1. A multi-layered biocide-containing plastic covering for agricultural cultivation, said covering comprising: (a) at least one upper layer of a plastic;

(b) at least one lower layer of a plastic; and

(c) at least one layer containing a biocide sandwiched between said upper layer and lower layer.

2. The covering of claim 1 wherein a user of said covering would lay said covering over a agricultural cultivation bed, puncture one or more apertures throughout said covering, plant agricultural cultivations within one or more of said apertures and allow one or more agricultural cultivations to grow through said apertures and allow said biocide to emit from said covering to the agricultural cultivations.

3. The covering of claim 2 wherein said covering further comprises one or more apertures for plant agricultural cultivation within one or more of said apertures and allowing said agricultural cultivation to grow through one or more of said apertures.

4. The covering of claim 1 wherein at least one of said upper layers of plastic is composed of an opaque material.

5. The covering of claim 1 wherein said biocide consists essentially of herbicides, pesticides, fungicides, rodenticides, and mixtures thereof.

6. The covering of claim 2 wherein said biocide has a vapor pressure whereby the biocide is released when the user punctures said apertures in said covering.

7. The covering of claim 1 wherein said biocide is encapsulated between said upper and said lower layers of plastic. 8. The covering of claim 1 wherein said biocide is laminated on either said upper layer or said lower layer of plastic.

9. The covering of claim 1 wherein said lower layer of plastic is liquid impermeable.

10. The covering of claim 1 wherein said upper and lower layers of plastic are liquid impermeable. 11. The covering of claim 1 wherein said covering further comprises a layer of nutrients, plant growth regulators, pheromones, defoliants and/or mixtures thereof situated below said lower layer of plastic.

12. The covering of claim 1 wherein said biocide-containing layer comprises channels wherein said biocide is entrained.

13. The covering of claim 12 wherein said channels are formed by a channeling agent.

14. The covering of claim 13 wherein said channeling agent consists essentially of polyglycol, polyhydroxyl, and polyamine.

15. The covering of claim 13 wherein said channeling agent consists essentially of polyethylene glycol, ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH) and glycerin.

16. A method of covering and protecting agricultural cultivations, said method comprising the steps of: (a) providing a covering comprising at least one upper layer of plastic, at least one lower layer of plastic and at least one layer of a biocide sandwiched between said upper layer and said lower layer to form said covering;

(b) laying said covering over an agricultural cultivation bed;

(c) puncturing one or more apertures throughout said covering; (d) planting agricultural cultivations within one or more of said apertures and allowing the agricultural cultivations to grow through one or more of said apertures; and

(e) allowing said biocide to emit from said covering to the agricultural cultivations thereby protecting the agricultural cultivations from infesting pests and parasites.

17. The method of claim 16 wherein the step of puncturing said cover is performed prior to laying said covering over the agricultural cultivation bed. 21. The method of claim 16 wherein at least one of said upper layers of plastic is composed of an opaque material. 22. The method of claim 16 wherein said biocide consists essentially of herbicides, pesticides, fungicides, rodenticides, and mixtures thereof.

23. The method of claim 16 wherein said biocide has a vapor pressure whereby said biocide is released when said covering is punctured with said apertures.

24. The method of claim 16 wherein said upper and lower layer of plastic are liquid impermeable.

25. The method of claim 16 wherein said lower layer of plastic is liquid impermeable.

26. The method of manufacturing a multi-layered biocide-containing covering for agricultural cultivation, said method comprising the steps of:

(a) providing at least one upper layer of plastic and at least one lower layer of plastic; and (b) sandwiching at least one layer containing a biocide between said upper layer and said lower layers of plastic to form said covering. 24. The method of claim 23 wherein said biocide is encapsulated between said upper and said lower layers of plastic.

30. The method of claim 23 wherein said biocide is laminated on either said upper layer or said lower layer of plastic.

31. The method of claim 23 further comprising of steps of forming channels within said biocide-containing layer and entraining said biocide within said channels.

32. The method of claim 26wherein said channels are formed by channeling agents.

33. The method of claim 27 wherein said channeling agent consists essentially of polyglycol, polyhydroxyl and polyamine.

34. The method of claim 27 wherein said channeling agent consists essentially of polyethylene glycol, ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVOH) and glycerin.

35. The method of claim 27 wherein said biocide-containing layer is a polymer and said method further comprises the step of admixing said biocide and said channeling agent with said polymer.

36. The method of claim 30 wherein said biocide and said channeling agent are admixed to said polymer when said polymer is in a molten state.

37. The method of claim 30 wherein said biocide and said channeling are admixed to said polymer before said polymer is in a molten state. 38. The method of claim 30 wherein said biocide, channeling agent and polymer are powders.

39. The method of claim 30 wherein said channeling agent is admixed with said polymer before adding said biocide.

40. The method of claim 27 wherein said biocide-containing layer is a polymer and said method further comprises the step of blending and reacting said channeling agent with said polymer to thereby form channels.

41. The method of claim 35 wherein said biocide is inj ected within said channels of said biocide-containing layer.

42. The method of claim 33 wherein at least one of said upper layer is composed of an opaque material. 43. The method of claim 23 wherein said biocide consists essentially of herbicides, pesticides, fungicides, rodenticides, and/or mixtures thereof.

44. The method of claim 23 wherein said biocide has a vapor pressure whereby said biocide is released when said covering is punctured with one or more apertures by a user.

45. The method of claim 23 further comprising the step of extruding said covering and cutting said covering into sheets of plastic material.

46. The method of claim 23 further comprising the step of cutting said covering into strips of plastic material.

47. The method of claim 23 wherein a catalyst is applied to said covering to release said biocide. 48. The method of claim 23 further comprising the step of forming a layer of nutrients, plant growth regulators, pheromones, defoliants and mixtures thereof and situating said layer below said lower layer of plastic.

49. The method of claim 42 further comprising the step of releasing said nutrients, plant growth regulation, pheronomes, defoliants and/or mixtures thereof into the soil of the agricultural cultivation bed and onto the agricultural cultivation.