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1. CA2106591 - REVETEMENTS AVEC POLYMERES NEUTRALISES CARBOXYLES, RETICULES PAR DES LIENS IONIQUES ET COVALENTS

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]
IMPROVED COATINGS WITH IONICALLY AND COVATFNTLY
CROSSLINKED INITIALIZE;D CARBOXYLATED POLYMERS
Field of the Invention
The present invention relates to polymeric coatings having improved barrier properties wherein the polymeric coating is a covalently crosslinked neutralized carboxylated polymer.
The present inveneion relates to controlled release fertilizers and particularly to fertilizer-pesticid2 compositions. The invencion is mcre particularly direceed to fertilizers and fertilizer-pesticide compositions to which thin film or ultrathin films or coatings of covalently crosslinked neutralized carboxylated polymers have been applied as an improved controlled release agent.
Related to this, the present invention is directed to methods for producing fertilizer and fertilizer-pesticide composiees coated with covalently crosslinked neueralized carboxylated polymers in addition to agricultural processes involving the USQ of such coated fertilizers and fertilizer-pesticide composites. In this regard, agricultural processes in which the fertilizer and fertilizer-pesticide composites coated with covalently crosslinked neutralized carboxylated polymers in accordance with the present invention may be applied include proccsses for enhancing vegetation including plant growth simulation and regulation as well as stimulation of seed Rermination.
Description o~ Prior ~
Solids he.g., substrates, pipes, slabs, sheets, etc.) can be protected from the external environment with the use of barrier or protective coating materials. For protection from water or moisture, polymer or organic materials are widcly used. For cost effectiveness, however, these materials are generally aoplied as thin films. The thickness of the film depends upon the desired degree of water protection. The thicker the film the more likely that water penetration would be slowed down. In practice, applying an effective thin coating is difficult because of the various stresses tending to make the file discontinuous (e.g., film-rupture, pin holes). Films will rupture when a threshold stress is exceeded. The lateral stress tending to rupture a file is inversely proportional to an exponential power of the film thickness. The thinner the file, the more easily it will rupture.
There are many applications for thickened or gelled solutions ~ of polymers in organic liquids which are quite diverse. There are also a number of physical and chemical techniques ror preparing such systems. The present invention concerns a process for forming a polymer coating having improved barrier properties.
Coatings which can be protect ve, dacarbazine or special purpose are usually applied at thicknesses or as high as 150 micrometers or thicker in order to provide the desired properties required of such coatings. Such high thicknesses are required in order to compensate for coating defects or for poor coating material properties.
Coatings with improved propercies may be applied as thin films having a thickness range of l-lOO micrometers, with a preferred range of 2-40 micrometers. In order for such coatings to be functional, the coating material should show improved barrier properties and be a continuous film with few or no defects.
The discovery of the film forming properties of ionicQllv and covalently crosslinked carboxylated polymers has made possible the extension of their use to coating applications, including controlled release products in agriculture (e.g., controlled release fertilizer). In controlled release fertilizer applications coatings of ionically and covalently crosslinked carboxylated polymers will act as barriers to water soluble constituents of the fertilizer, shielding them from premature release in aqueous environments for periods ranging from several days to several months. Because of their unique barrier properties ionically and covalently crosslinkad carboxylated polymers can potentially be used to make cost effective controlled release fertilizers. The benefits obtained by ;he use of these coatings can include labor savings, increased crop yield, increased nitrogen utilization efficiency and time savings. The amount of premium is proportional to the cost of coating used on the controlled release product. Therefore, it is of economic importance to use as little coating material as possible to make a desirable agricultural product.
The amount of coating which should be applied on the controlled release product, however, is not only dictated by economic considerations, but also by the required performance. In most cases the performance requirements include the control of the release or dissolving property of the agricultural material, achiev2ble with the application of coatings free of fine pinholes or defects. Herein lies the major problem .'.n controlled release fertilizer, particularly with exts.ing conventional coatings, because ;he thinner the coating or tne less coating mate;ial is applied the less likely that defect free coatings can be made. Thus, commercially available controlled release fertilizer products are with thick (>40 microns) coatings to yield acceptable performance (e.g., <20X release of water soluble nutrient in seven days in water at 20C). As a consequence, these products are expensive and have found limited uses. With the discovery of ionically and cova.ently crosslinked carboxylated polymers coatings, however, the application of thin (<40 microns), defect-free films on controlled release fertilizer can now be achieved/ thus, its use presents a potential route for makins affordable concrolled release fertilizer.
The instant invention teaches ehat a solution o~ a neutralized carboxylated polymer with a covalent crosslinking means can meet many of the requironents for forming an improved thin film coating.
Carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur are the primary elements esseneial to plant growth. Soils contain all of these elements in addition to other macro and micronutrients that enhance plant growth. Typically, however, such elements are seldom present in the soil in sufficient quantity or in forms that can support maximum plant productivity and field. Therefore, fertilizers having specific chemical formulations and in pre-determined amounts must be added to enrich the soil to ensure maximum plant yield. The amount and form of the fertilizer added are pre-determined by chemically assaying the amount and availability of the required nutrient(s) ` in the soil, for example, as disclosed by Methods of Soil Analysis, 1982, Amer. Soc. Agronomy, Madison, WI. Thus, appropriate fereilizer is added in amounts calculated to ensure the required plant field based on known fertilizer response curves established by extensive agronomic testing ior the particular plant and plant growth environment.
Fertilizers containing nitrogen, phosphorus, sulphur a~ o; potassium, by way of example, may be applied as solid granules or in liquid form. These primary fertilizers may be supplemen.ad wi th certain trace elements such as copper, iron, manganasa, zinc, cooai_, molybdenum, boron usually supplied as oxides or salts containing ehe elements in the cationic form. Suitable salts are, for a~am?la, sulphates, nitrates, chlorides, molybdates or borates. The difrerence between trace element deficiency and toxicity, however, is but a few parts per million as measured by the concentration of the element in the soil. Moreover, the efficiency of utilization of fertilizers, i.e., the percent uptake of the applied fertilizers is notoriously low. In this regard, chemical, biological and physical processes compete with the plant for the added fertilizer nutrients usually to the detriment of plant productivity. In addition, nitrogen rer~ izers added to the soil may be leached into groundwater, chemically immobilized into clay minerals, chemically removed by volatilization of ammonia, biologically removed from the soil by denitrification to dinitrogen and nitrous oxide gases or immobilized into tha active microbial biomass. these competing and simultaneous occurrences result in fertilizer use efficiency of nierogen oi`ten being less than 50X. thus, when TO0 kg N/ha is added to the soil, the plane actually "sees" only 50 kg N/ha. Although most soils contain high levels of phosphorus, it is chemically immobilized as calcium phosphates, e . g. in soils of pH > 7.0 or iron and aluminum phosphates, e.g. in soils of pH < 5.0, and is thus not plant-available. Fertilizer phosphorus applied to these soils, however, is rapidlv immobilized resulting in fertilizer use efficiencies seldom exceeding 30%.
If the release of nutrients from fertilizers could be controlled to more closely match the actual physiological requirements of the plant for the nutrient and if temporary or permanent losses of the fertilizer nutrients could be minimized if not eliminated, several advantages would accrue:
i~ less fertilizer would be required to achieve the same plant yield;
ii) the same amount of fertilizer could be applied resulting in higher yields and concomitant lower per unit plant production costs:
iii) less water-soluble nitrogen would leach into groundwaters thus minimizing ground-water pollution; and/or iv) less nitrogenous gases would evolve into the atmosphere thus minimizing damage to the fragile ozone layers
Although it is known to protect solid substrates, such as pipes, slabs, sheets and the like from the external environment with the use of barrier or protective coaeing materials, this technology has not been applied in accordance with the presen; invention. particularly with respect to agricultural products. In conventional applications, however, polymers or other organic materials are widely used as coaCings to provide protection from wacer or moisture For cost effectiveness these materials are typically appliad as thin
Pilms. The thickness of che ~ depends upon che desired degree of water protection. The thicker the file, the more likely that wacar peneCration would be slowed down. In practice, applying an effective thin coating is difficult because of the various stresses tending to make the film discontinuous (e.g., film-rupture, pin holes). Films will rupture when a threshold stress is exceeded. The laterial stress tending to rupture a film is inversely proportional to an exponential power of the film thickness. The thinner the film, the more easily i will rupture. Polymers containing associating ionic groups, i.e. ionomers, which have a high degree o- molecular interactions made excellent protective films. Covalently crosslinked networks of ionomers containing associating ionic groups can further improve the strength and barrier performance of the coatings.
There are many applications for thickened or gelled solutions of polymers in organic liquids. There are also a number of physical and chemical techniques for preparing such systems, The present invention, however, is concerned with polymeric coatings having improved properties which have been found to be particularly suicable for application to agricultural products. such as fertilizers. pes icLdes, herbicides, insecticides, bacteriocides, ~~-gicides, nematicide, sporicides, and the like, in addition to combinations thereof.
Detailed of the Invention
The present invention relates to a process for forming a polymeric coating having improved barrier properties from an organic solution of an organic liquid, a neutralized carboxylated polymer, and a means of covalent crosslinking.
In general, the present invention, therefore, relates to coating vegetation enhancement agencs, such as fertilizers and fertilizer-pesticide combinations, with thin or ultra-ehin coa;ings or ionically and cova].ently crosslinked carboxylate polymers to result in controlled release fartilizers 3nd fertilizer-pesticide combinations having improved barrier properties, as well as agricultural processes involving methods of using fertilizers and fertilizer-pesticide combinations coated with ionically and covalently, crosslinked, carboxylate polymers in accordance with ;he present inven;ion so as to decrease dissolution of soluble fertilizer components. increase fertilizer use efficiency and substantially decrease losses of the added fertilizer from the plant growth medium due to biological, chemical, or physical processes competing with the plant for the said nutrients.
Detailed gescription
The component materials of the instant invention generally include a water insolubla carboxylated polymer dissolved in an organic solvent system to form a solution with a concentration level of 0.1 to 20 weight percent, wherein the solution can contain a covalent crosslinking agent which is activated at a minimal temperature of 40C or alternatively, tha polymeric coating can be crosslinked by a post coating crosslinking means. The solvent system comprises an organic solvent with or without a polar cosolvent, such as alcohols amines or ammonia, The solvent can be an organlc liquid which is capable or dissolving the polymeric backbone. .~ cosolvent may be needed to break up associated domalns resut.ing from a~rega.ion of ionic species.
The present invention relates to a process for forming thin polymeric coatings which are both ionically and covalently crosslinked having improved barrier properties and physical properties from an organic solution of an organic liquid, a neutralized carboxylated poly,per and a covalent crosslinking means.
The thin polymeric coatings are coated on vegetation enhancements, e.g., fertilizer or fertilizer/pesticide combinations. The process of the instant invention genarally comprises an organic solution o~ a water insoluble carboxylaced polymer with a crosslinking agent which is not activated until a eemperaeure of 40C is obeained coating the organic solution of the water insoluble carboxylated polymer and the crosslinking agent onCo a substrate and sub;eceing ehe coated substrate to a temperature oP at least 40~C to aceivate the crosslinking agent thereby covalently crosslinking the carboxylated polymer. An alternative process comprises coating an organic solueion of the water insoluble carboxylated polymer on the substrate and subsequently subjecting the coated substrate to an election beam thereby covalently crosslinking the water insoluble carboxylated polymer A still alternate process comorises coating a substrate with an organic solution of the water insoluble carboxylaeed polymer and subsequently contacting the coated subserata with a vapor or solution of sulfur monochloride thereby forming a covalently crosslinked water
W O 92/17424 PCT/US92/OOOS~
insoluble carboxylated polymer. The sulfur monochloride can also be added to the organic solution of carboxylated polymer immediately prior to spray coating. It is contemplated within the scope of this invention that any two or more of these processes in conjunction could be used to crosslink the water insoluble carboxylated polymer. I- is also contemplated that the water insoluble carboxylated polymer could be covalently crosslinked either in solution or in a solid form to form a formed polymeric article of 0~5 to 40 mils thickness by anv one of the aforementioned processes. The covalently crosslinked ~a,er insoluble carboxylated polymers of the instant invention will comprise from about 1 to about 500 milliequivalents o.^ pendant carboxylate groups per 100 grams o polymer, more preferably from 5 to 300 meq. pendant carboxylated groups. The carboxylate groups are neutralized with counterions selected from, but not limited to, Groups IA, IB, IIA, and IIB of the
Periodic Table of Elements, as well as lead, tin, zinc and antimony, or ammonium and amine counterions.
The degree of neutralization of the carboxylate groups of the covalently crosslinked neutralized carboxylated polymers may vary from
O (free acid form.) to 100 mole percent, preferably 50 to 100 mole percent. With the utilization of covalently crosslinked neutralized carboxylated polymers in this instane invention, it is preferred thac 8hq degree of neutralization be substantially complete, thac is, with `~ no substantial free acid present and withoue subscantial excess of the base, other than ~hac needed to ansure neutralization. The covalently crosslinked neutralized carboxylates possess greater thermal stability and better mechanical properties (such as toughness) compared to their ~acid form. Thus, it is clear that the polymers which are normally utilized in the instant invention comprise substantially neutralized carboxylated groups and, in fact, an excess of the neutralizing : material may be utilized without defeating the objects of the ins~an~ invention.
The covalently crosslinked neu;ralized carboxylate polymers o~ the instant invention may vary in number average molecular weight from 1,000 to 10,000,000 preferably 5,000 to 1,000,000 most preferably from 10,000 to 600,000. These polymers may be prepared by methods known in the art, such as a copolymerization where one of the monomers is a carboxylate containing monomer.
Covalently crosslinked neutralized carboxylated polymers used in the instant invention are characterized by the formula:
CH2-CH2~X--(c~2-c3y wherein y is about 0.1 to about 30 mole percent, more preferably about 0.5 to about 20, and most preferably about 1 to about 15; R is hydrogen, an ethyl or a methyl group; wherein M+ is selected from the group consisting of ammonium, amine couneerions and metal counterions selected from, but not limited to, the group consisting of lead, antimony, zinc, tin and Groups IA, IB, IIA and IIB of the Periodic Table of Elements,
The concentration of ehe covalencly crosslinked neutralized carboxylated polymer in the solution of the covalently crosslinked neutralized carboxylated polymer, covalenc crosslinking agent and the organic solvent, and optionally the cosolvent, is abouc 0.1 to about 20 weight percent, more preferably about 0.5 to about 10, and most preferably about O.S to about 6Ø
The organic solvent is selected from the group consisting of aromatic solvents, oxygen-containing solvents, such as esters, ketones, ethers, aldehydes and carboxylic acids, and amines, amides, alcohols and mixtures thereof. Preferrea organic solvents are tetrahydroi`uran, acetic acid, xylene and toluene.
In order to reduce the viscosity of an organic solution of the neutralized carboxylated polymer so as to be able to employ the organic solution in a casting process, a polar cosolvent may be added to the organic solution of the neutralized carboxylated polymer to solubilize the pendant carboxylate groups. The polar cosolvent will have a solubility parameter of at least 10.0, more preferably at least 11.0, and may comprise from 0.01 to 15.0 weight percent, preferably 0.1 to 5.0 weight percent, of the cotal mixture of organic liquid, water insoluble neùtralized carboxylated polymer and polar cosolvene.
Normally, the polar cosolvent will be a liquid at room temperature, however, this is not a requ-cement. It is preferred, buna required, that the polar cosolvent D_ soluble or miscible with the organic lLquid at the levels employed in. this invention. The polar cosolvent is selected from the group consisting essentially of alcohols, amines, ammonia, amides, acetamides, phosphates, or lactones and mixtures thereof. Especially preferred polar cosolvents are aliphatic alcohols, such as methanol, ethanol, n-propanol, isopropanol, 1,2-propane diol, monoethyl ether of ethylene glycol, n-ethylformamide and meehyl isobutyl carbinol.
The polymeric coatings of the instant invention are formed by applying the organic solution or the carboxylated polymer and, optionally, the covalent crosslinking agent over the substrate at an ambient temperature of 10-70~C, buc at a tamperature lower than the activation temperature of the covalent crosslinking agent, by either dipcoating or spray-coating or with the use of ocher eechniques for thin spreading (such as brushing). The organic solvenc system is then permitted to evaporate with or without the aid of forced drying gas, such as air or nitrogen gas. This step is called the drying process. The drying gas temperature can be from ambient temperature up to the boiling point of the organic solvent system. Preferably the temperature or the drying gas is between 20C to 100C. The most preferred temperature of the drying gas should be aboue ~0C to about 70C for fast evaporation of the organic solvent system. After drying the thickness of the applied coating should be aboue 1 micrometer to abou. 100 micrometers. Most preferred, the coatin thickness should be about 2 to about 40 micrometers for both performance and economic reasons. To control the thickness of the applied coating, the solution concentration of the carboxylated polymeric and is applied at 0.5 to lO weight percent. Most preferably, the concentration should be about l to 6 weight percent. The coating solution of the carboxylated polymer can be applied in single or multiple layers, depending on the desired coating thickness. In any instance, the organic solvent system is evaporated after each layer application. The carboxylated polymer can be applied over the substrate of interest or over a previous coating.
In the latter case, such practice can modify or improve the performance of the coated system.
Covalent crosslinking of the abov- mentioned polymers can be carried out with a variecy of common vulcanization formulations involving crosslinking peroxides, carriers for crosslinking peroxides accelerators and sensitizers.
Examples of peroxide crosslinking agents include acetyl cyclohexane sulphonyl peroxide, bis (2-ethylhexyl) peroxydicarbonate, bis(4-tert butyl cyclohexyl) peroxydicarbonate, di-cyclohexyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-n-butyl peroxydicarbonate, dicetyl peroxydicarbonate, disecbutyl peroxydicarbonate, di-isopropyl peroxydicarbonate, tert butyl peroxyeodecanoate, bis 2,4-dichlorobenzoyl) peroxide, tert butyl percxy pivalate, bis (ortho-methyl benzene) peroxide, bis (ortho-methyl benzoyl) peroxide, bis (3,5,5-trimethyl hexanoyl) peroxida, dilauaryl peroxide, didecanoyl peroxide, di-octanoyl pqroxida, di-proprionyl peroxide, dibenzoyl peroxide, tert bueyl peroxy-2-2thylhexanoata, tert butyl peroxydiethylacetate, tert butyl peroxy isobutylate, bis (tert butyl peroxy isopropyl) benzene and others like them.
Possible carriers for the peroxide are contemplated to the calcium carbonate, clay, EVA copolymer masterbatch, EPDM-masterbatch, silicone oil, plasticizer as well as organic solvents.
Accelerators are contemplated to include thiazoles, sulfinamides, thiuram, dithiocarbamates, guanidines and ehioureas.
Sensitizers are contemplated to include trialkyl cyanurate, trialkyl isocyanurate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate.
The concentration of the covalenc crosslinking agent in the organic solution or carrier is about 0.1 to about 20 weight percent, more preferably about O.lS to about lS weight percent and most preferably about 0.17 to about 10 weight percent. The curing of the coating of the carboxylated polymer with the covalent crosslinking agent occurs during the aforementioned dr~ing step of the process at temperatures above 40C.
In the process of curing the carboxylated polymeric coating with an electron beam, the coating is first dried in the aforementioned drying scep of the process. The dried carboxylated polymeric coating is cured by exposure to an electron beam radiation at ambient temperature for a sufficient period of time (lO to 60 minutes) to cause covalent crosslinking, wherein the electron beam is l to 50
MRad, preferably 2. to 25, and most preferably 5 to 20.
Where sulfur monochloride is employed as the crosslinking agent, there are several approaches which may be sued to crosslink the coating. In a ~irsc embodiment, che substrate particles coated with the dried carboxylated polymeric coating is covalenely crosslinked by qxposing the coated particles to a saturaeed vapor of sulfur monochloride at ambient temperature for R sufficient period of time, hour to 48 hours, more preferably 2 to 36 hours, and most prererably lO to 30 hours, to cause covalent crosslinking. The coated polymer particles may be exposed to vapor by placing them on a screen in a desiccator or in a packed column and exposing the particles to the vapor for a period of time sufficient to cause covalent crosslinking of the sulfonated polymer.
In another variation of this process, the coated particles may be covalently crosslinked by con~ac~ with a solution of sulfur monochloride in an organic solvent selected from the group consisting of aliphatic, aromatic and haloganaced hydrocarbons. The concentration of sulfur monochloride in the solution should be about 1 to about 50 weight percent, more preferably 2 to 40 weight percent, and most preferably 3 to 30 weight percent. The amount o~ sulfur monochloride solution used to cross-link the polymer contains enough sulfur monochloride to equal about 1.0 to about 20 weight percent of to,e weight of polymer in the coating, more preferably abou; 2.0 to about 15 weight percent and most preferably about 3.0 to about 12 weight percent of the polymer. The solu.ion can be sprayed onto the coated particles bv any means which ensures uniEorm distribution and then the solution s permit.ed to evapora_e.
In yet another embodiment, crosslinking with sulfur monochloride may be car i-d out by direc. ac-~_ion o sulru monochloride to the sulfonated polymer solution i~ec_a~e'y ?rior .o spray coating.
The amount of sulfur monochloride added may range from the weight of about 1.0 to about 20 weight percent based on the weight of the sulfonated polymer to which it is added, more preferably about 2.0 to about 15 weight percent and most preferably about 3.0 to about 12 welght percent of the polymer. The spray coating and drying process is then carried out as described above:
The ionically and covalently crosslinked carboxylaced polymer coating can be used as a barrier to crea;e des}red slow release for many types o~ fertilizers, micronuCriancs or ocher solid maeerials either individually and/or in mixtures, suitable for purposes of the prcsene inveneion including by way of e~ampla:
MACRONUTRIENTS
Nitrogen, for example provided by:
Ammonium sulphate
Ammonium chloride
Ammonium nitrate
Diammonium phosphate
Ammonium phosphate nitrate
Monoammonium phosphate ammonium phosphate sulphate
Wo92/~7424 2~a~9~ Pcr~us92/oooc-
Sodium nitrate
Potassium nitrate
Calcium nitrate
Urea
Ammonium nitrate-calcium carbonate mixture
Potassium, for example provided by: ~ .
Potassium nitrate
Sulphate of potash
Muriate o~ potash Potassium metaphosphate
Phosphorous, for example provided by:
Ammonium phosphate nitrate
Ammonium phosphate sulphate ~ .
Monoammonium phosphate
Diammonium phosphate :Single superphosphate
Triple superphosphate
Poeassium metaphosphate `
Sulfur, for example provided by:
Ammonium sulphato
Ammonium phosphato sulphato
Sulphate potash
Calcium sulfatie
Ammonium bisulphite
Ammonium phosphate
Ammonium polysulphide
Ferrous sulphate
Gypsum
Kalinite
Leonite
Magnesium sulphate
Polyhalite
Pyrite
Schoenite
Sodium sulphate
Sulphur
Sulphur dioxide
Single superphosphate
Urea sulphur
Zinc sulphate
Calcium, for example provided by:
Calcium nitrate
Calcium sulfate
Calcium chloride MICRONUTRIENTS
Boron as:
Borax (sodium tetraborate decahydrate)
Sodium tetraborate pentahydrate
Sodium tetraboraee-pentaborate
Colemanite
Copper as:
Cupric oxide
Curous oxide
Cupric sulphate nonahydraee
Ferrous sulphace heptahydrace
Manganese as:
Manganous carbonate
Manganous oxide
Manganous-manganic oxide
Manganous sulphate monohydrate
Molybdenum as:
Ammonium molybdate
Sodium molybdate (anhydrous)
Molybic oxido 0 92/1742q PCT/US92/OOOY
Zinc as:
Calcinated zinc concentrate
Zinc carbonate
Zinc oxide
Zinc sulphate monohydrate
Conventional slow release fertilizers may also be coated with the ionically and covalently crosslinXed carboxylated polymers in accor- . dance with the present invention, such as:
Sulphur coated urea Glycouril
Isobutylidene diurea Magnesium ammonium ,
Crotonylidene diurea phosphate (Mag AmD)
Urea formaldehyde Cuanyl urea sulphate
Trimethylene tetraurea (GUS) :Oxamide Guanyl urea phosphate
Cyanuric acid (GUP)
Ammeline Thiourea
Ammedllde Phenylurea
Urease or nitrification inhibitors can be included with the fertiliæers, Examples of such inhibitors include urease inhibitors such as phenyl phosphoro-dlamidata (PPD) and N-(n-bucyl) chiophosphorie triamida (NBPT) and nierification inhibitors such as N-serve (s-chloro-6-trichloromethyl pyridine) and deeyandiamide (DCD)~
The present invention is particularly suitable for combinations of the aforementioned fertilizers with any pestieide although the present invention can be practiced with fertilizers and/or pesticides alone. Examples of suitable pesticides include herbicides such as triallate and trifluralin, insecticides such as carbofuran and aldicarb, fungieides such as captan and benomyl, rodenticides such as warfavin and chlorophacinone, o-ethyl s,s-dipropyl phosphorodithioate nematicides such as o,o-dethyl o-(p-methylsulfinyl) phenyl phosphorate, ascaricides such as kelthane and plictran, and bacteriocides such as strypcomycin and terramycin
The plant growth media to which the fertilizers and fertilizer-pesticide composites coated in accordance with the present invention may be applied include liquid cultures i e , hydroponics, soil-less cultures and any mixture of sand, vermiculite, peat, perlite, or any other inert or relatively inert support, and soils which can be either irrigated or rainfall soils
The seeds or plan.s envisioned to be fertilized by the instant invention include any species .allied in the Plant Kingdom examples, of such include the follow ~g cereals, such as wheat, maize (corn), rice, barley, oa.s; grass-s such as bluegrass, fescues, bromegrass (for forage, seed and/or tur^ production); legumes such as alfalfa, soybean, bean, ?eas, len_ils; __ls-ecs suc;~ as canola, palm, cotton, olive, flax vegetables such -â to,aloes, le.euce~ celery, carrot, onion, tomatoes, peppers; other Droadleaf plants such as mint; coniferous and dec duous trees and shrubs and flowers such as chrysanthemum, roses and tulips
It should be understood, however, that the inclusion of herbicides with fertilizers coated with ionically and covalently crosslinked carboxylated polymers are not inconsistent with the term vegetation enhancement agent which is intended to be applied to the desired or tar8et plane, The fact the: harbicide may kill Indesired vegetation does noc diminish its role as a vegetaCion enhancement agent for others, particularly the v~ge~acion for which ehs fertilizer is intended,
The previc,usly listed fertilizers, pesticides, either individually and/or in mixtures, may be coated with ionically and covalently crosslinked carboxylaeed polymers in accordance with the present invention In rhis regard, th- substrate of the vegetation enhancement agent for purposes of tn- present invention may be a member selected from the group consist ng of macronutrients, micro- ~ ; nutrients, nitrogen fertilizers inc _ding inhibitors of urease, nitrogen fertilizers including inhibitors of nitrification activity, slow release fertilizers, and pesticides, in addition to mixtures of a plurality of each of the macronutrient s, micronuerienes, nitrogen fertilizers including inhibitors of urease, nitrogen fertilizers including inhibitors of nitrification activity, slow release fertilizers and pesticides, as well as mixtures of members from each group of macronutrients, micronutrients, nitrogen fertilizers including inhibitors of urease, nitrogen fer.ilizers including inhibitors of nitrification activity, slow release fertilizers and pesticides. In addition, the fertilizers and fertilizer/pesticide combinations coated with ionically and covalently crosslinked carboxylated polymer in accordance with the present invention may be fixed with non-coated fertilizers and/or pesticides of the sæ~- or differant composi.ion.
In this regard, to.e non-costed member ~zy be selected from the group consisting of macronutrients, micronu.rients, nitrog2n fertilizers including inhibitors or urease, nitrogen rertilizers including inhibitors of nitrification activity, slow release fertilizers and pesticides in addition to mixtures of a plurality of each of the groups of vegetable enhancement agents as well as mixtures of one or more members of each of the previously mentioned groups. When this is the case, the fertilizer or fertilizer/peseicide combination coated with the ionlcslly and covalently crosslinked carboxylated polymer in accordance with the present invention may comprise 5 to 95X by total weight of the mixture or the non-coated vegetation enhancement agent may comprise 5 to 95X by total weight of the mixture.
The plant growth media co which the fertilizers and fertilizer-pesticide composites coated in accordance with the present invention may be applied include liquid cultures, i ~ B ., hydroponics, aoil-less cultures and any mixture o~ sand, vermiculite, peat, perlite, or any other inert or relatively inert support, and soils which can be either irrigated or rainfed solids.
A varieey of substrates which are discrete particulace solids may be encapsulated to form advantageous products. In some applications substrates are required to be released in a slow or controlled manner in given environments. Examples include: fertilizers, micronutrients, coated seeds, synthetic reagents or catalysts, pharmaceuticals and drugs. Substrates can also be modified b encapsulation in cases where their solid surfaces need to be more compatible when they are added to other materials. Examples are engineering plastics, adhesives or rubbers with incorporated filler particles, such as ground lime, carbon blark, titanium dioxide, or zinc oxide.
The vegetation enhancemen. agent, i.e., fertilizer or fertilizer/pesticide combination, to which the present invention is applicable is preferably in a substantially solid form, ~ e., particles, having a dimension, and preferably a major dimension, within the range o^ about 1.0 to 10.0 mm. Preîerably, tne fertilizer particles are granules having a diame^er wi,hin the -2n~e Or about 1. O to 6.0 mm and most preferably about ~.0 to aoou~ 3.~ m~. Commercial fertilizer granules typically have a dieter o- ebout 2.3 mn, although particles, such as granules naving a diameter as large as about 6 mm, have been found to be useful, particularly _or purposes of aerial application, for example used in the forestry industry
Although the present invention has been described in connection with coating a vegetation enhancement agent, such as fertilizers/pesticide combinations, with a layer or film of ionically and covalently crosslinked carboxylated polymer, it should be understood that the present invention may also be used to coat a previously coated fertilizer or fertilizer/pesticide combination, such as conventional slow release fertilizers. Alternatively, rer~ili2ers coated with ionically and covalencly crosslinked carboxylated polymers in accordance with the present inveneion may also be coated with a conventional slow release coating, to whicn additional applications of the ionically and covalently crosslinked carboxylaced polymer films or coatings in accordance with the presenc invention may be applied.
Thus, a multiple-coated fertilizer or fertilizer/pesticide combination may be produced in accordance with ehe present invention. In this regard, however, it is preferred tha. .he film or coating of the ionically and covalently crosslinked carboxylated polymer or interpolymer complex be either in direc. contact with the vegetation enhancement agent, or form the exterio surface of ,he coated composite
The present invention is also directed to agricultural processes, such as those for the enhancement of vegetation or vegetable matter. As used herein, vegetable matter is meant to be a division of nature comprising the plant kingdom 25 distinguished from matter of animal and mineral o -gin. Thus, vegetable latter includes seeds and plants, including seedlings, young plants, or any organ from which a plant can be generated, includinv naturally promulgated vegetable matter in addition to genetically engineered vegetable matter.
More speci call;, chc process or the present invention is directed to the simulation of tha germination and growth of a seed or a plant, including seedlings, voung plants or any organ from which a plant can be generated, which involves the s.e? of exposing ehe vegetable matter, e g., the seed or plant, and/or ;he plant growth medium, i.e., soil, water and the like, either before, simultaneously with, or after the addition of the seed or plant to the plant growth medium to a fertilizer and/or fertiliæer-pesticide combinations having 8 thin layer of a carboxylated polymer coated thereon.
In addition, the process also relates to the intimate admixing of fertilize, such as urea, ammonical, phosphorus and/or sulphur fertilizers, alone or combined with pesticides, with a seed or planes or other vegetable fatter, as defined herein, wiehouc damage to ehe same in a plant growth medium which involves che steps of:
1) admixing o~ ocherwise contacting a fertili7er, preferably in solid granular form, having a thin ionically and covalently crosslinked carboxylated polymer or interpolymer complex film or coating thereon with a seed or plant;
2) placing such a fertilizer in close proximity to the seed or plant with or without a separation of time between the fertilizer and seedling steps.
In this regard, i~ has been discovered chat fertilizers with thin films or coatings of ionically and covalently crosslinked carboxylated polymers, for example urea and ammonium sulfate, can be placed with the seed at the rate exceeding 25kgN/ha without damage to the seed, seedlings, or young plants. Thus, the fertili er and fertilizer/pesticide combinations having thin films or coatings of ionically and covalently crosslinked carboxylated polymers have been found to be extremely effective in stimulating seedling emergence and early plant growth by permitting the placement of urea fercilizers with the seed at .he time of planting. It has been discovered that the thin ionically and covalently crosslinked carboxylated polymer film or coating slows the release of urez and a~oni~m to a su.efficient. extent to prevent burning oî the seed o~ young seedling to which such a fertilizer is aDplied. In contras. tO conventional slot relaase fertilizers, for e:sample, urea coatea witn a thin ilm of ionically and covalently crosslinked carboxylated polymqr in accordance with the present invention can be applied to the plant growth media at a rate in excess of 25kgN/ha without raising t;he pH of the seed in the plant media a sufficient extent to burn the seed and prevent emergence.
Although phosphorous fertilizers are routinely seed-placed and have been found to be effective ln stimulation of emergence and yield, known as the "pop-up" effect, seed-placing has not believed to have been possible with conventional ammonical nitrogen fertilizers prior to the development o~ the ionicallv and covalentlv crosslinked carboxylaced polymer coated fertilizers and fertilizerJpesticidq combination in accordance with the presene invencion. Thus, the carboxylated polymer coated fertilizers and ~artilizer~pescicide combinations in accordance with the prasant invention have been found to be particularly advantageous in promoeion of emergence, and early growth stimulation of seedlings, while permitting placement of the fertilizer with the seed. .
Although the coated fertilizer of the present invention has been found to be pareicularly advantageous in permitting the introduction of nitrogen fertilizers and fer~ilizer/pesticide combinations simultaneously into ehe soil with the seed so as to stimulate emery gence of seedlings and the growth of plants, fertilizers coatqd in accordance with the present invention may also preferably contain a source of sulfur and phosphorous, in which case, the fertilizer may beapplied so as to supply nitrogen at a rate in excess of 25kg/ha, sulfur in excess OL- 15kg/ha, and phosphorous at a rate in excess of 30kg/ha without burning the sePds or preventing subsequent emergence of the seedlings.
The present invention, therefore, is particularly suitable for replacing split or multiple applications of uncoated fertilizers to ensure that the available plant nu-rient matches the physiological need of the crop for the same. In this -e~a_~, plants to not require all of their nitrogen at onP ~i me; or e.couple, wheat requires over 35X of its nitrogen bet~esn booting and ~;he soLt touc:~ stage. Typically uncoated fertilize_s are applied .. split apolications a~ key physiological plant growth stages such as tillering, step elongation, booting and seed filling to ensure that :he nitrogen is available to the plant as required. Controlled release nitrogen, therefore, is effective in replacing split fertilizer applications. Controlled release nitrogen holds the nitrogen in a form until the nitrogen is needed by the plant. It has been discovered that the sulfonated polymer coated fertilizer and fertilizer/pesticide combinations in accordance with the present invention are particularly suitable for introduction with the seed and/or into ehe planc growth median during a single agricultural step so as to ~ali~inace the need for post emergence applicacion of the fertilizer.
he fertilizer and fertili~er/pasticida combination coated with thin films of ionically and covalently croaslinked carboxylated polymers in accordance with the presene invention, however, may also be introduced into the soil prior to a subsequent planting of the seeds. For example, the coated fertilizer of the present invention may be introduced into the soil in the Fal' of a year prior to planting wheat in the spring of the followin2 year, without appreciable loss of nutrients. Thus the coated fertil ze of the present invention may be formulated so as to supply nitrogen at a sufficient rate and timing of release to satisfy the physiolo,ical need for nitrogen of ehe wheat beginning in the Spring of the :ear when the wheat is soon through the growing season. The coated -ertilizer of the present invention may also be applied in a single application to supply nitrogen at a rate and timing of release essentially the same as provided by separate applications of fertilizer prescribed under a standard intensive cereal management program (ICM) thereby elimina.ing the need for multiple fertilizer applications wnich would otherwise bê required-by such an ICM program.
In view of the foregoing, it is believed that the ionically and covalently crosslinked carboxylated polymer coating of fertilizers in accordance with the present invention, and Darticularly ~hos~haee fertilizers, would effectively reduce the chemical immobili-ation ophosphorous as calcium or aluminophosphate, thereby fertilizer phosphorous more piano ava~'la~ie.
In accordance with the present invention, fertili-ers and fertilizer/pesticide combinations with thin films or coatings of ionically and covalently crosslinked carboxylated polymers permits the fertilizer to be applied to the soil at a rate which is at least lOX less than a fertilization rate for a fertilizer not coated in accordance with the present invention determined by a standard soil testing method as being required for the particular crop in the soil of the particular region. Although the raee of fertilizer reduction may be as much as about SOX less than the fertilization face otherwise required, cypically the race is reduced within the range o~ about 10-20X less than a conventional fertilization rate
It has been discovered chat fertilizers and ~ertilizer/pescicide combinacions coated with thin films of ionically and covalently crosslinkad carboxylated polymer experienca reduced nitrogen losses. This is particularly true for urea and ammonium sulfate, Conventionally, nitrogenous fertilizers added .o mois. soils, i.e,, soils where the moisture levels exceed 2/3 of field capacity, i.e., 22kPa, are subject to a loss of nitrogen due to a variety of factors including: leaching into ground waters, the denitrification to N2O and/or N~ gas, volatilization of ammonia gas, and immobilization into the active microbial biomass. I- nas beer discovered cac fertilizers coated win, .hin films of ionically. and covalently crosslinked carboxylated polymers in accordance with the present invention experience substantially reduced losses of nitrogen by controlling the release of nitrogen bY the coated fertili-or; thus, the amount of fertilizer nitrogen available at any particular time which would be subjected to the previously mentioned dele,erious effects is minimized. An advantage of the present invention, therefore, is a reduction in the losses of, for example, ammonical nitroven by chemical, physical and biological occurrences. Thus, the present invention has been found effeccive in incraasing plan. yields because more nicro~en is available for the needs of the plan., while decre2sing pollueion of ground water with. per.Ill'per-derived nitrates, decreasing destruction of the ozone layer of .he acmosphere due co fertilizer-derived ~.~G, and incr-asl-.~ -sidual ni.Mogen to benefi. subsequent crops planted during the normal course or agricultural rotation.
Preferred Embodiment
The following Examples demonstrate the performance of a neutralized carboxylated polymer as a barrier coating.
Example 1
Improved Barrier P~Q~ es Of Can laced Poller Coa~in~s
Two different radars of zinc-ethylene/mac~a-ac-ylic acid carboxylated polymers (Surlyn 9910 and Surlyn 9970 madP by DuPonc Co,) were dissolved in boillng tetrahydrofuran (THF). The polymer concentration of each solution was 2 weight percent. these solutions were used for dip coating of the polymer over soiid, dry urea samples in order to determine the barrier properties of che encapsulated urPa to waeer extraction.
To determine barrier properties of -ilms formed from solution, urea slides were coated for immersion teses. The procedures rorpreparing coated samples of urea slides ar.d conducting immersion tests are described as follows:
Urea samples were prepared by depositing reagent grade urea (Fisher Scientific) over microscope glass slides. This was done by dipping glass slides into molten urea at a temperature o~ about 135-145C, followed by cooling and solidification of the urea lzyer
The urea layer was built up to about 7 ~ by four to five successive dipping and cooling cycles. These urea samples were then coated by a polymeric film using a second dipping procedure Urea slides were repeatedly dipped into polymer solutions, such as those described above, followed by drying in a vacuum oven at 70C for about 3 hoùrs.
The dipping and drying cycles were repeatad until the film thlc~:nesses shown in Table I were obtained. The carboxylated polymer solu.ions in
THF were kept at an elevated temperature of 40-60C during the dipping process to avoid polar precipitation.
The barrier properties of the various polymeric films were determined by immersion of each coated urea slide in about TO0 g of deionized water at room temperature. The amount of urea released into the water was determined by recovering the urea after evaporating che water. Each sample was initially immersed for l day, followed by immersion in fresh water for 3 days and for weekly intervals thereafter.
Table I shows the permeabilitias of urea solution traced from the coated slides which were immersed in water at room cemperature. The permeabilities of the coating materials were determined bv applying Fick's law of diffusion at steady state. Fick's law statas that:
where Jm mass flux (loss) through the ^ilm or membrane, .A = transport area, ~C ~ concentration gradient, ~ = filn or membrane thickness and D ~ membrane diffusivity constant which is equal to the ratio of permeability (P) over the solubilit: ratio (K) of urea in thmembrane and in water.
The performance of the carboxylated polymer coatings was compared with that of two commercially used coating materials. The first commercial coating solution was 2 tung oil solution made by
Formby of Mississippi a~ 30 weight percent solids in petroleum distillate. The second com.mercial coating so~_ ion ~2S linseed oil modified polyurethane Type I made by Minwa-.c ?aint Co. of New Jersey at 4~% solids in petroleum distillate. The -wo commercial coatings were cured at 70C for 48 hours after coating.
The permeability of urea solution through the cargo.~:yla_ad polymer films was found ;o be abou ers o- magni.ude lo-he. .han either that of tung oii or tha. of po ; he;h2ne. Tu.,g oil and polvurethane were disclosed 2S rela25e C~.._-_' coa.ings lor water soiuble fertilizers in U.S. ~a;end Nos. 3.321.~ and 3,233,51S.
The reason for scatcer in the permeability data for ;he carboxylated polymer coatings shown in table I is believed to be a result of the coating quality. Existence of pin holes will increase the apparent permeability as calculated above. One should, therefore, assume that the lowest number corresponds to a more perfect coating.
Permeabilities for the other polymers in Table I do, on ;he other hand, agree with literature data for perfect coatings with these polymers.
This Example shows that encapsulaced urea having a carboxylated polymer coating is much more resistant to extraction bwater than is the urea encapsulated by commercially used coaeings.
One can, therefore, apply a thinner soaeing of the carboxylated polymer for equivalent results to obtain a cost advantage or the carboxylated polymer coatings can be useful for a slower release.
TABLE I
Permeability of Urea Solution from Coated
Urea Slides in Water at Room Temperature 141-3 Tung Oil 7S 4.3 x lO-9 141-6 Tung Oil 125 7.6 ~.~ 10-9 : 158-4 Polyurethane lOO 1.3 x lO-q 158-5 Polyurethane 40 2.1 ~ lO-9 :
S-9910 Carboxylated Polymer 70 4.2 x 10-9
S-9970-A Carboxylated Polymer 70 2.7 ~ lo-ll
S-9970-B Carboxylated Polymer 70 2.~ x 10-1 .Example 2
Fluidized Bed Process for Surlyn 9970 Coating
The Surlyn 9970 coated fertilizer granules are produced using :~ the following contemplated procedure: .,
4 Xg of 2 eO 3 mm fertilizer granules are introduced into a fluid bed coating machine, including a Wurster insert, manufac:urea by
Glatt Air Techniques Inc,, model number GPCG-5~ The fertilizer is fluidized by blowing 200 scfm of heated air (70~C) through bed. Aftar the bed reaches a temperature o~ 50~C, a 2.5 waighe percent hot solution oi` the Surlyn 9490 polymer in toluene and methanol cosolvent and methyl isobutyl carbonat is sprayed onto the fertilizer granules at the Wurster insert entrance. The spray nozzle uses was a commercial two fluid nozzle using air at 2 bars pressure to form an atomized spray regime in the Wurster insart.
The spraying is continued at 300 gm/min (probably up to 500 gm/min) rate until .he required thickness of polymeric coating is built up on the fertilizer, i.e. approximately 12 minutes per a coating level of 1 wt,X polymer on the fertilizer.
After the solution is sprayed onto the granules in the
Wurster insert, the thus coated granules are blown bv the heated air upwards into the drying section of the machine. Here, the solvents are evaporated by ,he hot air, leaving a thin coat of dried polymeric material on the granules. The dried granulas ,all back into ,he fluid bed and then re-enter the Wurster insert where the coating process is repeated. Thus, multiple films or layers of the Surlyn 9970 polymeric coating is built up until the spraying wzs stopped.
The spraying is cor. r.sea un.i_ ~ ~.h Surlyn ~970 is addad.
The spraying is stor,ped and ~:.a coatad _~-nutes ara dried ~-ich he .~o~ air for 5 minutes. The produce is loggec anc is marked ~ w-,~ of
Surlyn 9970 on fertilizer.
Example 3
The contemplated method for crosslinking the polymer using electron beams is as follows:
Granular fertilizer pellets in the size range of 2 to 3 mm . coated with 5 wt.X per Surlyn 9970 are placed in a monolayer on a flat bed cart. The cart is placed in an electron beam generator unril a dose of 10 Megarads is obcained.
Example 4
The contemplated mathod for c~os31inking Surlyn 99/0 with sulfurmonochloride is as follows:
Approximately 100 g of coated pallets consisting oi ~ wt.~.
Surlyn 9970 on 2-3 mm granular fartilize a-e placed in a monolaver in a flat dish. The dish was then put into a desiccator wnich contains a separate dish with 0.5 grams of liquid sulfur monochloride. The desiccator is closed and evacuated so ~~.a~ only sulfur monochloride vapor remains. The pellets ara ieff ir. Cha dasiccator for 2- molars.
After that thev are removed and placed ir. _ vacuum oven a~ 40'C for 10 to 12 hours in order to ramova rasidual su'-ur monochloride.