CA2104688A1 - Ionically and convalently crosslinked biodegradable barrie films of ionomer polymer - Google Patents

Abstract

2104688 9217422 PCTABS00016 An encapsulated water soluble fertilizer which comprises a polymeric film of about 2 to about 100 micrometers coated on a surface of said fertilizer, said polymeric film comprising a covalently crosslinked sulfonated polymer having about 10 to about 200 meq of sulfonate groups per 100 grams of said covalently crosslinked sulfonated polymer, said sulfonate groups being neutralized with a polycaprolactone polymer being characterized by formula (I) wherein R1 and R2 is an alkyl, cycloalkyl or aryl group; R3, R4, and R5 are a hydrogen or alkyl, cycloalkyl, or aryl groups;
m equals 1 to 20 and n equals 1 to 500.

Description

W O 92/17422 2 1 0 ~ 6 ~ 8 PCT/US92/00045 IONICALLY AND COVALENTLY CROSSLINKED
BIOD~RADABLE BARRIER FILMS OF IONOMER POLYMER

Field of the Invention This invention relates to an unsupported polymeric film as well as an encapsulated water soluble fertilizer or pesticide, or herbicide products which comprlses a polymeric film of about l to about l00 micrometers coated on a surface of said fertilizer, said poly~eric film comprising a covalently, crosslinked, sulfonated polymer having about l0 to about 200 meq of sulfonate groups per l00 grams of said covalently crosslinked sulfonated polymer, said sulfonate groups being neutralized with a polycaprolactone poly~er being characterized by the formula Rl R4 R3 0 \ I I , .....
N-(C~mNC(CH2)5[0c(cH2)5]n-loH

wherein Rl or R2 is an alkyl, cycloalkyl or aryl group; R3, R4 and Rs are a hydrogen or alkyl, cycloalkyl, or aryl groups; m equals l to 20 ant n equals l to 500.

The present invention relates to controlled release matcrials, e.g., fertilizers, micronutrients, herbicites, pesticites, ant particularly to fertilizer-pesticide compositions. The invention is more psrtlcularly directed to fertilizers and fertilizer-pesticide compositions to which thin film or ultrathin films or coatin~s of ionically and covalently crosslinked sulfonatet polymers and amine terminated polycaprolactone have been applied as an improved con-trolled release agent. Related to this, the present invention is disected to methods for psoducing fertilizer and fertilizer-pesticide composites coated with sulfonated polymers in addition to agricultural processes involving the use of such coated fertilizers and fertilizer-pesticide composites. In this regard, agr~cultural processes in which the fertil~zer and fertilizer-pesticide composites coated with : , . . - . : , . , ~ : : : ::
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- 2 ionically and covalently crosslinked sulfonated polymers and amine terminated polycaprolactone in accordsnce with the prssent in~ention may be applied include processes for enhancing vegetation includ~ng plant growth stimulation and regulation as well as stimulation of seed germination.

Background of the Inve~tion The present invention relates to the compositions of assoc~-ating polymer protective barrier f~lms, which w~ll protect materials, such as agricultural chemicals, for a period of time and then degrade and releas~ the encapsulated contents to the environment. More specifically, this invention relates to the preparation of ionomer compositions containing compa~ibilized polymers which will be degraded by microorganisms.

It is extremely important today to find an effective means of degrading polymeric materials, which are used in packaging and agri-cultural films. In the case of mechanical goods, the pollution problem is becoming more severe as used plastic bottles, containers, wrapping film, sheet, etc., accumulate in garbage dumps, along shores, in rivers and other places. There is a great need for some sort of tegrading system that will allow the plastic to have a useful life, after which the plastic will degrade into a material that can be handled easily. In other film applications, controlled release of encapsulated materials requires environmental degradation.

This invention provides new polymer~c systems capable of degrading to a crumbly friable mass. These systems are based on the ability to produce compatible polymeric films from ionically and co~alently crosslinked sulfonated polymers and amine terminated poly- .
csprolactone. The ionically ant covalently crosslinked sulfonated polymer can be in the free acid form or neutralized with a metal which can coordinate with the amine. The co~bination makes excellent coatings, films and mechanical goods due tO the compatibilization of the multiple polymer blend. The degradability comes from the inherent ~ characteristic of polycaprolactone, suscepeibility to biodegradation.
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:., ~ ' -W O 92/1~422 2 1 0 ~ 6 8 8 PCT/US92/00045 The advent of plastics has introduced improved methods of packing goods. For example, polyethylene and polypropylene films, bags and bottles and polystyrene foa~ cups ha~e the advantages of being chemically resistant, mechanically tough, light ln weight and inexpensive. However, the increasing use of plastics in packa~ing has led to the appearance of such materials in litter. Wh~le littered plastic articles are no more ob~ectionable than littered articles of other mater~als, such as paper ob~ects and metal cans, it has be~n suggested that the impact of plastic litter can be minimized by the development of plastic materials capable of undergoing chemical degradation upon exposure to the natural environment.

Several approaches to the enhancement of the environmental degradability of plastics have been sug~ested. These include: (1) the incorporation of particulate biodegradable materials, such as starch, as "fillers"; (2) the introduction of photodegradation-sensitizing groups into the molecular structure of a pqlymer by copolymerization of a common monomer with a second monomer processing such ~roups; and (3) the incorporation of small amounts of selected additives which accelerate oxidative and/or photo-oxidative degrada-tion. The last approach is particularly attractive for the following reasons. First, the physical properties of the additive-containing composition are extremely similar to those of the base polymer.
Second, existing compounding and fabrication processes and equipment ; can be utilized in the manufacture of finished products; hence, the cost of the finished product should be relatively low. Third, the sensitivity of the composition to environmental degradation can be controlled by proper selection of the type of concentration of addi-tive(s).

The enhancement of the rate of environmental deterioration of polymers through the use of oxidation-promoting additives is known in the prior art. For example, the preparation of degradable polyolefin films containing certain organic derivatives of transition metals is described in U.S. Patent No. 3,454,510.

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Various type additives have been employed in polymeric film in order to make the polymeric film biodegradable. For example, in U.S. Patent No. 4,224,416 auto-oxidizable amines are employed. In U.S. Patent No. 3,994,855 a photolyzable metal compound is employed.
U.s. Patent No. 4,495,311 employs an additive system consisting of a ~etal co~pound having at least two valence states and a benzoyl derivative of an organic compound.

The present invention describes a polymer system which is biodegradable in film form. The polymer system of the instant inven-tion comprises a compatible mixture of an ionically and covalently crosslinked sulfonated polymer with an amine terminated polycaprol-actone. Compatible mixtures of sulfonated elastomeric poly~ers and amine terminated polycaprolactone are described in U.S. Patent No.
4,421,898; however, U.S. Patent No. 4,421,898 failed to teach or recognize the usè of these polymer mixtures in their film form as an agricultural mulch.

Carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur are the primary elements essential 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 yield. Therefore, fertilizers having specific chemical formulations and in pre-determined amounts must be added to enrich the soll to ensure maximum plant yield. The amount and form of the fertilizer added are pre-determined by chemi-cally assaylng the amount and availability of the required nutrient(s3 in the soil, for example, as disclosed by Methods of Soil Analysis, 1982, Amer. Soc. Agronomy, Madison, WI. Thus, appropriate fertilizer is added in a~ounts calculated to ensure the required plant yield based on known fertilizer response curves established by extensive agronomic testing for the particular plant and plant growth environ-ment.
, Fertilizers containing nitrogen, phosphorus, sulphur and/or potassium, by way Gf example, may be applied as solid granules or in . .
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,' " ' ' ': ' ' 2i~688 liquid form. These primary fereilizers may be supplemented with certain micronutrient trace elements such as copper, iron, manganese, zinc, cobalt, molybdenum, boron usually supplied as oxides or salts contafnin~ the elements in the cationic form. Suitable salts are, for example, sulphates, nitrates, chlorides, molybdates or borates. The difference between trace elemene deficiency and toxiclty, however, is but a few parts per milllon 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 fertilizers added to the ~oil may be leached into groundwater, chemi-cally immobilized into clay minerals, chemically removed by volatiliz-ing of ammonia, biologically removed from the soil by denitrification to dinitrogen and nitrous oxide gases or immobilized into the active microbial biomass. These competing and simultaneous occurrences result in fertilizer use efficiency of nitrogen often being less than 50X. Thus, when 100 kg N/ha is added to the soil, the plant actually ; "sees" only 50 kg N/ha. Although most soils contain high levels of phosphorus, it is chemically i~mobilized 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. Fertillzer phosphorus applied to these soils, however, is rapidly immobilized resulting in fertilizer use efficiencies seldom exceeding 30X.
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I~ the release of nutrients from fertilizers could be con-trolled to more closely match the actual physiological requirements of the plant for the n~trient and if temporary or permanent losses of the fertilizer nutrients could be minimized if not eliminated, several advantages would accrue:

; i) less fertflizer would be required to achieve the same plant yield;

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W O 92/1~422 2 1 ~ i PCT/US92/0Q045 ii) the same amount of fertiliz~r could b~ appli~d ~esulting in hi8her yields and concomitant lower per unit plant productLon costs;

iii) less water-soluble nitrogen would leach into ground-waters thus ~inimizing ground-water pollution; and/or iv) less nitrogenous gases woult evolve into the atmosphere thus minimizing damage to the fragile ozone layer.

Although it is known to protect solid substrates, such as p~pes, slabs, sheets and the like from the external environment with the use of barrier or protective coating materisls, this technology has not been applied in accordance with ~he present invention, parti-~ularly wieh respect to agricultural products. In conventional applications, however, polymers or other organic materials are widely used as coatings to provide protection from water or moisture. For cost effectiveness these materials are typically applied 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 tifficult 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 lateral stress tending to rupture a film is inversely proportional to an exponential ; power of the film thickness. The thinner the film, the more easily it will rupture. Polymers containing associating ionic groups, i.e.
ionomers, which have a high degree of molecular interactions make excellent protective films. Covalently crosslinking networks of iono~ers containing associating ionic groups can further improve the strength and barrier performance of these coatings.
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; There are many applications for thic~ened 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 i~proved properties which have been found to be particularly suitable ::
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W O 92/1742~ 2 ~ 0 ~ 6 ~ 8 PCT/US92JoO04s for application to agricultural products, such as fertilizers, pesti-cides, herbicides, ins0cticides, bacteriocides, fungicides, nemati-cide, sporicides, and the like, in addition to co~binations thereof.

Sum~8rY of the Inve~ion The present inven~ion relates to a procsss for preparing a polymeric film composition which is susceptible to chemical degrada-tion in the environment by preparing a composition comprising a compatible mixture of an ionically and covalently, crosslinked, sulfonated polymer and an amine terminated polycaprolactone, and subsequently subjecting the prepared composition in the form of a polymeric film to be a biodegrading en~ironment. -In general, the present invention also relates to coating vegetation enhancement agen~s, such as fertilizers and fertilizer-pesticide combinations, with thin or ultra-thin coatings of ionically and eovalently crosslinked sulfonated polymers with an amine termin-ated polycaprolactone to result in controlled release fertilizers and fertilizer-pesticide combinations having improved barrier properties, as well as agricultural processes invol~lng methods of using ferti-lizers and fertilizer-pesticide combinations coated with ionically and covalently crosslinked sulfonated polymers with amine terminated polyeaprolaetone in accordsnce with the present invention so as to deerease tissolutlon of soluble fertilizer components, inerease fertilizer use effieiency and substantially decrease losses of the adted fertilizer from the plant growth medium due to biological, chemical, or physical processes competing with the plant for the saLd nutrients. ~-Detailed ~escription of the Invention The thin polymeric coatin~s are coated on vegetation enhance-ments, e.g., fertilizer or fertilizer/pesticide combinations.

The process of the instant invention generally comprises an organic solution of a water insoluble carboxylated polymer with a :
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is obta~ned; coating the organic solution of ths water insoluble sulfonated polymer and an amine terminated polycaprolactone and the crosslink~ng agent onto a substrate and subjecting the coated sub-strate to a temperature of at least 40-C to activate the crosslinking agent thereby covalently crosslinking the sulfonated polymer. An altarnative process comprises coating an organic solution of the water insoluble sulfonated polymer and amine terminated polycaprolactone o~to the substrate and subsequently sub~ecting the coated substrate to an election beam thereby covalently crosslinking the water insoluble sulfonated polymer. A still alternative process comprises coating a substrate w~th an organic solution of water insoluble sulfonated polymer and amine tsrminated polycaprolactone and subsequently con-tacting the coated substrste with a vapor or solution of sulfur monochloride thereby forming a covalently crosslinked water insoluble sulfonated polymer. It is contemplated within the scope of this invention that any one or all three of these processes in conjunction could be uset to crosslink the water insoluble sulfonated polymer and amine terminated polycaprolactone. It Ls also contemplated that the water insoluble sulfonated polymer and amine terminated polycaprol-actone could be covalently crosslinked either in solution or in a solid form to form a formed, unsupported polymeric article having a thickness of 0.5 to about 40 mils by any one of the aforementioned ; processes.

The component materials of the instant process generally include a water insoluble sulfonated polymer and amine terminated polycaprolactone 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 40-C. The solvent system comprises an organic solvent with or without a polar cosolvent, such as alcohol, amine, or ammonia. The solvent can be an organic liquid which is capable of dissolving the polymeric backbone. A cosolvent may be needed to break up associated domains resulting from aggrega-tion of ionic species.

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W O 9~/17422 PCT/US92/00045 The polymeric films of the instant invention are formed fro~
a compaeible mixture of a ionically and covalently crosslinked sulfon-atsd elastomeric polymer and an amine terminated polycaprolactone.
The ionically and covalently crosslinked sulfonated polymers may be in the free acid form or they can be neutralized salts with metals capable of coordinating amino groups or the sulfonated groups are complexed with a metal ion which is capable of coordinating with the amino group of the polycaprolactone polymer.

The ionically and covalently crosslinked neutralized, sulfon-ated polymers of thLs present invention are derived from elastomeric polymers wherein the elastomeric polymers are derived from unsat~rated polymers which include low unsaturated elastomeric polymers, such as butyl rubbers or EPDM terpolymers.

Alternatively, other unsaturated polymers are selected from the group consisting of partially hydrogenated polyisoprenes, partial-ly hydrogenated polybutadienes, Neoprene, styrene-butadiene copolymers or isoprene-styrene random copolymers.

The expression "Butyl rubber" as employed in the specifica-tion and claims is intended to include copolymers made from a poly-merization reaction mixture having therein from 70 to 99.5 by weight of an isoolefin which has about 4 to 7 carbon atoms, e.g., iso-butylene, and about 0.5 to 30Z by weight of a conjugated multiolefin having from about 4 to 14 carbon atoms, e.g., isoprene. The resulting copolymer contains 85X to 99.8X by weight of combined isoolefin and 0.2X to 15Z of combined multiolefin.

Butyl rubber generally has a Staudinger molecular weight as measured by GPC of about 20,000 to about 500,000, preferably about 25,000 to about 400,000, especially about lO0,000 to about ~00,000 and a Ui~s Iodine No. of about 0.5 to 50, preferably l to l5.
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For the purposes of this invention, the Butyl rubber may have incorporated therein from about 0.2Z to l.OX of combined multiolefin, .
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prsferably about 0.5X to about 6X, more preferably about lX to about 4X, ~.g., 2X.

Illustrativs of such a Butyl rubber is Exxon Butyl 365 (Exxon Chemical Company), having a mole percent unsaturation of about 2.0%
and a Mooney viscosity (ML, 1 + 3, 212-F) of about 40-50.

Low molecular weight Butyl rubbers, i.e., Butyl rubbers having a viscosity average molecular weight of about 5,000 to 85,000 ant a mole percent unsaturation of about lX to about 5X may be sul-fonated to produce the polymers useful in this invention. Preferably, these polymers ha~e a viscosity average molecular weight of about 25,000 to about 60,000.

The EPDM terpolymers are low unsaturated polymers having about 1 to about 10.0 weight percent olefinic unsaturation, more preferably about 2 to about 8, most preferably about 3 to 7~ defined ~ccording to the definition as found in ASTM-D-1418-64 and is intended to mean terpolymers containing ethylene ant propylene in the backbone ant a diene in the side chain. The preferred polymers contain about 40 to about 75 weight percent ethylene ant about 1 to about 10 weight percent of a diene monomer, the balance of the polymer being propylene. Preferably, the polymer coneains about 45 to about 70 weight percent ethylene, e.g., 50 weight percent, and about 2.6 to - about 8.0 weight percent diene monomer, e.g., 50 weight percent. The ;
diene monomer is preferably a nonconjugated diene.

Illustrative of these noncon~ugated diene monomers which may be used in the terpolymer (EPDM) are 1,4-hexadiene, dicyclopentatiene, 5-ethylitene-2-norbornene, 5-methylene-2-norbornene, 5-propenyl-2-norbornene, ant methyl tetrahydroindene.
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A typical EPDM is Vistalon 2504 (Exxon Chemical Company), a terpolymer having a Mooney viscosity (ML, 1 + 8, 212F) of about 40 and having an ethylene content of about 50 weight percent and a 5-ethylidene-2-norbornene content of about 5.0 weight percent. The ~n as measured by GPC of Vistalon 2504 is about 47,000, the ~v as . . .
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WO g2/1742~ 2 1 0 ~ 6 8 8 PCT/US92tOQ045 measured by GPC is about 145,000 and the ~ as measured by CPC is about 174,000.

Another EPD~ terpolymer, Vistalon 2504-20, is derived from Vistalon 2504 ~Exxon Chemical Company) by a controlled extrusion process, wherein the resultant Mooney viscoslty at 212-F is about 20.
The ~n as measured by CPC of Vistalon 2504-20 is about 26,000, the Hv as measured by GPC is about 90,000 and the ~w as measured by GPC is about 125,000.

Nordel 1320 (DuPont) is another terpolymer having a Mooney viscosity at 212-F of about 25 and having about 53 weight percent of ethylene, about 3.5 weight percent of 1,4-hexadiene and about 43.5 weight percent of propylene.

The EPDM terpolymers of this invention have a number average molecular weight (Hn) as measured by GPC of about lO,OOO:to about 200,000, more preferably of about 15,000 to about lQ0,000, most preferably of about 20,000 ~o about 60,000. The Mooney viscosity (ML, 1 + 8, 212-F) of ~he EPDM terpolymer is àbout 5 to about 60, more preferably about lO to about 50, most preferably about 15 to about 40.
'rhe ~ as measured by GPC of the EPDM terpolymer is preferably below about 350,000 and more preferably below about 300,000. The ~w as measured by GPC of the EPDM terpolymer is preferably below about 500,000 and more preferably below about 350,000.

In carrying out the invention the polymer is dissolved in a nonreactive solvent, such as a chlorinated aliphatic solvent, chlori-nated aromatic hydrocarbon, an aromatic hydrocarbon, or an aliphatic hydrocarbon, such as carbon tetrachloride, dichloroethane, chloro-benzene, benzene, toluene, xylene, cyclohexane, pentane, isopentane, hexane, isohexane or heptane. The preferred solvents are the lower boiling aliphatic hydrocarbons. A sulfonating agent is added to the solution of the elastomeric polymer and nonreactive solvent at a temperature of about -100C to about 100C for a period of time of about 1 to about 6Q minutes, most preferably at room temperature for about 5 to about 45 minutes; and most preferably about 15 to about 30.
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The~e sulfonating agents are selected from an acyl sulfate, a mixture of sulfuric acid and an acid anhydride or a complex of a sulfur trloxide donor 3nd a Lewis base containing oxygen, sulfur or phos-phorous. Typical sulfur trioxide donors are S03, chlorosulfonic acid, fluorosulfon~c acid, sulfuric acid, oleu~, etc. Typical Lewis basss are dioxane, tetrahydrofuran, tetrahydrothiophene or triethyl phos-phate. The most preferred sulfonation agene for this invention is an acyl sulfate selected from the group consisting essentially of benzoyl, acetyl, propionyl or butyryl sulfate. The acyl sulfate can be formed in situ in the reaction medium or pregenerated before its addition to the reaction medium in a chlorinated aliphatic or aromatic hydrocarbon.

It should be pointed out that neither the sulfonating agent nor the manner of sulfonation is critical, provided that the sulfon-ating method does not degrade the polymer backbone. The reaction is quenched with an aliphatic alcohol, such as methanol, ethanol or isopropanol, with an aromatic hydroxyl compound, such as phenol, a cycloaliphatic alcohol, such as cyclohexanol, or with water. The unneutralized sulfonated elastomeric polymer has about 10 to about 200 meq. unneutralized sulfonate groups per 100 grams of sulfonated polymer, more preferably about 15 to about 100, and most preferably about 20 to about 80. The meq. of unneutralized sulfonate groups per 1000 grams of polymer is tetermined by both titration of the polymeric sulfonic acid and Dietert sulfur analysis. In the titration of the sulfonic acid the polymer is dissolved in solvent consisting of 95 parts of toluene and 5 parts of methanol at a concentration level of 50 grams per liter of solvent. The unneutralized form is titrated with ethanolic sodium hydroxide to an Alizarin-Thymol-phthalein endpoint.

The unneutralized sulfonated polymer is gel free and hydro-lytically stable. Gel is measured by stirring a given weight of polymer in a solvent comprised of 95 toluene-5-methanol at a concen-tration of 5 weight percent for 24 hours, allowing the mixture to settle, withdrawing a weighed sample of the supernatant solution and evaporating to dryness.

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Hydrolytically stable mesns that the acid funotion, in this case the sulfonic acid, wLll n~t be eli~inated under neutral or slightly basic conditions to a neutral moiety which i5 incapable of being converted to hlghly ionic functionality.

Neutralization of the unneutralized sulfonated polymer can be accomplished hy the addition of a solution of a polycaprolactone polymer typically dissolved in the mixture of the aliphatic alcohol and nonreactive solvent. The polycaprolactone polymer is dissolved in a solvent system consisting of toluene, optionally containing an aliphatic alcohol. These polycaprolactone poly~ers are formed by the reaction of ~-caprolactone with an organic dia~ine in the presence of a catalys~ as described in U.S. Patent No. 4,421,898. The anhydrous e-caprolactone and the organic diamine in the presence of the catalyst are reacted together in a reaction vessel in the absence of a sol~ent at a temperature of about 50 to about 200-C, more preferably about 75 to about 180~C and most preferably about 90 to about lOO~C for a sufficient period of time to effect polymerization.

The reaction of e-caprolactone with the diamine can generally be depicted by the equation:

RlR4 R3 \ I 1 11 N(C)mNH +n ~ catalvst e-caprolactone Rl~4 R3 o \ l l l N(C)",NC(CH2)5[0C(CH2)5]n l0H
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R2R5 o wherein n - 1 to 500; m 1 to 20; Rl or R2 are selected from the group consisting of alkyl and cycloalkyl groups having about 1 to about 20 carbon atoms, more preferably about 1 to about 12 carbon ., :

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W ~ 92/17422 2 1 ~ ~ 6 8 8 PCT/US92/00045 atoms, and aryl groups; R3 is selected fro~ the group consisting of hydrogen, alkyl and cycloalkyl groups having about 1 to about 20 carbon atoms, more preferably about 1 to about 12, and aryl groups;
and R4 and Rs are hydrogen, alkyl, cycloalkyl or aryl groups. Typical bue nonl~miting examples, of useful diamines are:

\ NCH2CH2CH2NH2 \ NCH2CH2CH2NH

CH3 \

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CH3N CH2CH2NH~
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\ N(CH2)nNH2 where n > 1 Catalysts useful in the promotion of the above-identified reaction are selected from the group consisting of stannous octanoate, stannous hexanoate, stannous oxalate, tetrabutyl titanate, a variety of metal organic based catalysts, acid catalysts and amine catalysts, as described on page 266 and forwarded in a book chapter authored by R. D. Lundberg and E. F. Cox entitled Kinetics and Mechanisms of Polvmerization: RLn~ O~enin~ Polvmerization, edited by Frisch and Rugen, publi~hed by Marcell Dekker in 1969, wherein stannous octanoate is an especially preferred catalyst. The catalyst i5 added to the reaction mixture at a concentration level of about 100 to about 10,000 parts of catalyst per one million parts of ~-caprolactone.

The resultant polycaprolactone polymer has an ~n as measured by GPC of about 200 to about 50,000, more preferably about 500 to about 40,000, and most preferably about 700 to about 30,000, and a .: ........ . - ,, , . - :
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W O 92/174~2 2 1 ~ ~ ~ 8 ~ PCT/USg2/OOW5 melt~ng point from below roo~ eemperature to aboue 55-C, more prefer-sbly about 20-C to about S2-C, and most prefersbly about 20-C to about 50^C.

Ths metal sulfonate-containing polymers at the higher sul fonate levels possess extremely high melt viscosities and are thereby difficult to process. The addition of ionic group plasticizers markedly reduces melt v~scosity and frequently enhances physical properties.

To the neutralized sulfonated polymer is added, in either solution or to the crumb of the unneutralized form of the sulfo~lated polymer, a preferential plasticizer selected from the group consisting of carboxylic acids having about 5 to about 30 carbon atoms, more preferably about 8 to about 22 carbon atoms, or basic slats of these carboxylic acids, wherein the metal ion of the basic salt is selected from the group consisting of aluminum, ammonium, lead or Groups IA, IIA, IB and IIB of the Periodic Table of Elements and mixtures thereof. The carboxylic acids are selected from the group consisting of lauric, myristic, plamitic or stearic acids and mixtures thereof, e.g., zinc stearate, magnesium stearate or zinc laurate.
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The preferential plasticizer is incorporated into the neu-tralized sulfonated polymer at less than about 60 parts by weight per lO0 parts of the sulfonated polymer, more preferably at about 5 to about 40, and most preferably about 7 to about 25. Alternatively, i - other preferential plasticizers are selected from ureas, thioureas, amines, amides, ammonium and amine slats of carboxylic acids and mixtures thereof. The preferred plasticizers are selected from fatty acid or metallic slats of fatty acid and mixtures thereof. The resultant neutralized sulfonated polymer with preferential plasticizer is isolated from the solution by conventional steam stripping and filtration.
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The biodegradable films or coatings of the instant invention are formed by applying the organic solution of the sulfonated ionomer (e.g., zinc sulfo EPDM with 25 meq. of sulfonate group) and of the .
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W O 92/174~2 PCT/US92/0004~
-amine terminated caprolactone (e.g., poly- c csprolaceone 3-dimethyl amino propylamine) over a substrate at ambient temperature or at 10-70-C by either dip-coating or spray-coating or with the use of other techniques for thin spread~ng (such as brushing). The organic solution can be prepared by mixing a proportionate weight of about l-lOX ZSE-25 with l-lOX poly-~ caprolactone 3-dimethyl amino propyl-amine, both in Solvent A. Solvent A comprises 85-97.5X toluene or other appropriate hydrocarbon and 15-2.5X or other alcohol. The organic solvant is permitted to evaporate with or without the aid of forced drying gas, such as nitrogen gas. This step is called the drying process. The drying gas can be from ambient temperature up to the boiling point of the organic solvent system. Preferably, the temperature of the drying gas is between 20C and lOO-C The most preferred temper.sture of the drying gas should be about 70C for fast evaporation of the organic solvent system. After drying the thickness of the applied film or coating should be about l to about lOO micro-meters. Most preferred, the coating thickness should be about 2 to about 40 micrometers for both performance and economic reasons. To control the thickness of the film or coating the solution of this instant invention is applied at 0.5 to 6 weight percent. Most prefer-ably, the concentration should be about 5 weight percent. The film of this instznt inventLon can be applied in single or multiple layers, depending on the desired film or coating thickness. In any instance the organic solvent system is evaporated after each layer application.
The biodegradable polymer film or coating can be applied over the sub-strate or over a previous coating. In the latter case, such practice can modify or improve the performance of the coated system.

The polymeric coatings of the instant invention are formed by applying the organic solution of the sulfonated polymer and amine terminated polycaprolactone and optionally the covalent crosslinking agent over the substrate at an ambient temperature of 10-70C, but at a temperature lower than the activat~on temperature of the covalent crosslinking agent, by either dip coating or spray-coating or with the sue of other techni~ues for thin spreading (such as brushing). The organic solvent system is ehen permitted to evaporate with or without aid of forced drying gas, such as air or nitrogen gas. This step is ",~

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called the drying process. The drying gas temperature can be from A~bient temperatura up to the bollin~ point of the or~anic solvent system. Preferably the temperature of the dryin~ gas is between 20C
to lOO-C. The most preferred temperature of the dryin~ gas should be about 70-C for fast evaporation of the organic solvent system. After drying the thickness of the applied coating should be about 1 micro-meter to about 100 micrometers. Most preferred, the coating 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 sulfonated polymer and amine ter-minated polycaprolactone is applied at 0.5 to 10 weight percsnt. Most preferably, the concentration should be about 1 to about 5 weight percent. The coating solution of the sulfonated polymer and amine terminated polycaprolactone 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 sulfonated poly~er and amine terminated polycaprolactone coating 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 above mentioned polymers can be carried out with a variety of common vulcanization for~ulations 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 peroxydi-carbonate, dicetyl peroxydicarbonate, disecbutyl peroxydicarbonate, di-isopropyl peroxydicarbonate, tert butyl peroxyeodecanoate, bis ; (2,4-dichlorobenzoyl) peroxide, tert butyl peroxy pivalate, bis (ortho-methyl benzene) peroxide, bis (ortho-methyl benzoyl) peroxide, . bis (3,5,5-trimethyl hexanoyl) peroxide, dilauaryl peroxide, di-decanoyl peroxide, di-octanoyl peroxide, di-proprionyl peroxide, di-benzoyl peroxide, tert butyl peroxy-2-ethylhexanoate, tert butyl . ~

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W O 92~17422 2 1 0 -~ 6 8 ~ PCT/US92/OOW5 - 18 .

peroxydiethylacetate, tert butyl peroxy isobutylate, bix (tert butyl peroxy isopropyl) benzene and others like them.

Possible carriers for the peroxide are contemplated to thE
calcium carbonate, olay, EVA copolymer masterbatch, EPDM-masterbatch, silicone oil, plasticizer as well as organic solvents.

Accelerators are contemplated to include thiazoles, sulfin-~mites, thiurams, dithiocarbamates, guanidines and thioureas.

Sensitizers are contemplated to include trialkyl cyanurate, trialkyl isocyanurate, trimethylolpropane trimethacrylate, ethylene glycol timethacrylate.

~ he concentration of the covalent crosslinking agent in the organic solution or csrrier is about O.l to about 20 weight percent, more preferably about 0.15 to about lS weight percent and most prefer-ably about 0.17 to about lO weight percent. The curing of the coating of the carboxylatet polymer and amine terminated polycaprolactone with the covalent crosslinking agent occurs during the aforementioned drying step of the process at temperatures above 40'C.

. In the process of curing the sulfonated polymer and amine terminated polycaprolactone coating with an electron beam, the coating is first dried in the aforementioned drying step of the process. The dried sulfonated polymer ant amine terminated polycaprolactone coating is cured by exposure to an electron beam radiation at ambient tempera-ture for a sufficient period of time (lO to 60 minutes) to cause ,., covalent crosslinkLng, wherein the electron beam is 1 to 50 MRad, preierably 2 to 25, and most preferably 5 to 20.
, ,. ~ ' , Where sulfur monochloride is employed as the crosslinking agent, there sre several approaches which may be used to crosslink the coating. In a first embodiment, the substrate particles coated with dried sulfonated pnlymer and amine terminated polycaprolactone coating is covalently crosslinked by exposing the coated particles to a saturatet vapor or sulfur monochloride at ambient temperature for a .
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W O 92tl7422 2 1 0 ~ ~ 8 8 PCT/US9t/00045 sufficient period of time, 1 hour to 48 hours, more preferably 2 to 36, and most preferably 10 to 30, to CaUSQ covalently 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 crossl~nked by contact w~th a solution of sulfur monochloride in an organic solvent selected from the group consisting of aliphatic, aromatic and halogenated hydrocarbons. The concentra-tion of sulfur monochloride in the solution should be about 1 to about 50 weight percent, ~ore preferably 2 to 40 weight percent. The amount of sulfur monochloride solution used to cross-link the polymer con-tains enough sulfur monochloride to equal about 1.0 to about 20 weight percent of the weight of polymer in the coating, more preferably about

3.0 to about 12 weight percent of the polymer. The solution can be sprayed onto the coated particles by any means which ensures uniform distribution and then the solution is permitted to evaporate.

In yet another embodiment, crosslinking with sulfur mono-chloride may be carried out by direct addition of sulfur monochloride to the sulfonatet polymer solution immediately prior to 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 wQight percent of the polymer. The spray coating and drying process is then carried out as described above.

The ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone coating can be used as a barrier to create tesired slow release for many types of fertilizers, micro-- nutrients or other solid materials either individually and/or in mixtures, suitable for purposes of the present invention including by way of example:
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W O 92~17422 ~ PCT/US92/OOWS

., MACBONUTRIENTS

Nitrogen, for example provided by: i Ammoniu~ sulphate Ammonium chloride Ammonium nitrate Diammonium phosphate Ammonium phosphate nitrate ~onoam~onium phosphate Ammonium phosphate sulphate Sodium nitratc Potassium nitrate Calcium nitrate Urea Ammonium nitrate-calcium carbonate mixture Potassium, for example provided by:
Potassium nitrate Sulphate of potash Nuriate of potash Potassium metaphosphate Phosphorous, for example provided by:
Ammonium phosphate nitrate : Ammonium phosphate sulphate Monoammonium phosphate Diammonium phosphate Single superphosphate Triple superphosphate Potassium metaphosphate :, : Sulfur, for example provided by: .
. Ammonium sulphate .
: Ammonium phosphate sulphate Sulphate potash Calcium sulfate Am~onium bisulphite .~ :

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W O 92/17422 2 1 ~ ~ 6 8 8 PCT/~S92/00045 Ammonium phosphate Ammonium polysulphide Ferrous sulphate Gypsum Kalinite Leonite ~agnesium 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 , ~:
NICRONUTRIENTS

Boron as:
Borax (sodium tetraborate decahydraee) Sodium tetraborate pentahydrate Sodium tetraborate-pentaborate Colemanite : Copper as:
Cupric oxide Curous oxide ; C~pric sulphate nonanhydrate Ferro~s su1phlto heptahydrate ', ' :, .
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W O ~2t1~4~2 2 1 ~ ~ ~ 8 ~ PCT/US92tOOW5 Manganese as:
~an~anous carbonate Manganous oxide Manganous-manganic oxide Manganous sulphate monohydrate Molybdenu~ as:
Ammonium molybdate Sodium molybdate (anhydrous) Molybic oxide Zinc as:
Calcinated zinc concentrate Zinc carbonate Zinc oxide Zinc sulphate monohydrate Conventional slow release fertilizers may also be coated with the crosslinked interpolymer complex polymers in accordance with the present invention, such as:
:, Sulphur coated urea Glycouril : Isobutylidene diurea Magnesium ammoniu~
Crotonylidene diurea phosphate (Mag Amp) Urea formaldehyde Guanyl urea sulphate . Trimethylene tetraurea (GVS) ::~ Oxamide Guanyl urea phosphate .` Cyanuric acid (GUP) : Ammeline Thiourea Ammedlide Phenylurea . Urease or nitriiication inhibitors can be included with the fertilizers. Examples of such inhibitors include urease inhibitors such as pheyl phosphoro-diamidate (PPD) and N-(n-butyl) thiophosphoric triamide (NBPT) and nitrification inhibitors such as N-serve (2-chloro-6-trichloro-methyl pyridine) and dicyandiamide (DCD).

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~ ' ;. - . ' ' . ~: : '-- :. . , . ~ . . -W O 92/17422 2 1 0 ~ 6 g 8 PCT/U592/00~45 The present invention is particularly suitable for combina-tions of the aforementioned fertilizers with any pesticide although the present invention can be practiced with fertilizers and/or pesti-cides alone. Examples of suitable pesticides include herbicites such as triallate and ~rifluralin, insecticides such as carbofuran and aldicarb, fungicides such as captan and benonyl, rodenticides such as 0-ethyl s,s-dipropyl phosphorodithioate-warfavin and chlorophacinone, and nematocides such as o,o-diethylk o-(p-methylsulfinyl) phenyl phosphonate, ascaricides such as kelthane and plictran, and bacterio-cides such as treyptomycin and terromycin.

The plant growth media to which the fertilizers and ferti-lizer-pesticide co~posites coated in accordancs 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 rainfed soils.

The seeds or plants envisioned to be fertilized by the instant invention includes any species falling in the Plant Kingdom.
Examples of such include the following: ceresls such as wheat, maize (corn), rice, bsrley, oats; grasses such as bluegrass, fescues, bromegrass for forage, seed and/or turf production; legumes such as alfalfa, soybeans, beans, peas, lentils; oilseeds such as canola, palm, cotton, olive, flax; vegetables such as potatoes, lettuce, celery, carrot, onion, tomatoes, peppers; other broad leaf plants such as mint; coniferous and deciduous 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 sulfonated poly~ers and amine terminated polycaprolactone are not inconsistent with the term vegetation enhancement agent which is intended to be applied to the desired or target plant. The fact that herbicide may kill undesired vegetation does not diminish its role as a vegetation enhancement agent for others, particularly the vegetation for which ~he fertilizer is intended.

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W O 92/17422 ~CT/US92/00045 The previously listed fertilizers and pesticides, either individually and/or in mixtures, may be coated with ionically and covalcntly crosslinked sulfonated poly~ers in accordsnce with the present invention. In this regard, the substrate of the vegetation enhancement agent for purposes of the present invention may be a member selected from the group consisting of macronutrients, micro- ¦
nutrients, nitrogen fertilizers including inhibitors of urease, nitrogen fertilizers including inhibitors of nitrification activity, slow ralease fertilizers, and pesticides, in addition to mixtures of a plurality of each of the macronutrients, micronutrients, nitrogen fertilizers including inhibitors of urease, nitrogen fertilizers including inhi~itors of nitrification activity, slow release ferti-lizers and pesticides, as well as mixtures of members from each group of macronutrients, micronutrients, nitrogen fertilizers including inhibitors of urease, nitrogen fertilizers including inhibitors of nitrification activity, slow release fertilizers and pesticides. In addition, the fertilizers and fertilizer/pesticide combinations coated with ionically and covalently crosslinked sulfonated polymer a~d amine terminated polycaprolactone in accordance with the present invention may be mixed with non-coated fertilizers and/or pesticides of che same or different composition. In this regard, the non-coated member may be selected from the group consisting of macronu~rients, micro-nutrients, nitrogen fertilizers including 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 groups of vegetable enhancement agents as well aR mixtures of one or more members of each of the previously mentioned groups. When this is the case, the fertilizer or ferti-lizer/pesticide combination coated with the ionically and covalently crosslin~ed sulfonated polymer and amine terminated polycaprolactone in accordance with the present invention may comprise 5 to 95% by total wei~ht of the mixture or the non-coated vegetation enhancement agent may comprise 5 to 95X by total weight of the mixture.
i 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, .: : . : -~ . : : .
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W O 92/~742~ ~ 1 0 4 6 8 8 PCT/US92/00045 so$1-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 rainfed soils.

A variety of substrates which are discrete particulate solids may be encapsulated to form advantageous products. In some applica-tions substrates are required to be released in a slow or controlled manner in given environments. Exs~ples include: fertilizers, micro-nutrients, costed seeds, synthetic reagents or catalysts, pharma-ceutical and drugs. Substrates can also be modified by 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 black, titanium dioxide, or zinc oxide.

The vegetation enhancement agent, i.e., fertilizer or fertilizer/pesticide combination, to which the present invention is applicable is preferably in a substantially solid form, i.e., particles, havin~ a dimension, and preferably a major dimension, within the range of about 1.O to 10.0 mm. Preferably, the fertilizer particles are granules having a diameter within the range of about l.0 to 6.0 mm and most preferably about 1.0 to about 3.5 mm. Commercial fertilizer granules typically have a dismeter of about 2.3 m~"
although particles, such as granules havin~ a diameter as large as about 6 mm, have been found to be useful, particularly for purposes of aerial application, for example used in the forestry industry.

Although the present invention has been described in con-nection with coating a vegetation enhancement agent, such as fertilizers/pesticide combinations, with a layer or film of car-boxylated polymer, it should be understood that the present invention ~ay also be used to coat a previously coated fertilizer or fertilizer/pesticide combination, such as conventional slow release fertilizers. Alternatively, fertilizers coated with covalently crosslinked sulfonated polymer and amine terminated caprolactone in accordance with the present invention may also be coated with a conventional slow ~elease coating, to which additional applications of ~
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W 0 92/17422 2 1 ~ Ll ~ 8 8 PCT~US92/00045 the covalently crosslinked sulfonated polymer and amine terminated polyc~prolactone films or coatings in accordance with the present invention may be applied. Thus, a multiplç-coated fereilizer or fertilizer/pesticide combination may be produced in accordance with the present in~ention. In this regard, however, it is preferred that the film or coating of the covalently crosslinked sulfonated polymer and amine terminated polycaprolactone be either in direct contact with the vegetation enhancement agent, or form the exterior surface of the 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 as distinguished from matter of animal and mineral origin. Thus, vegetable matter includes seeds and plants, including seedlings, young plants, or any organ from which a plant can be generated, including naturally promulgated vegetable matter in addition to genetically engineered vegetable matter.

More specifically, the process of the present invention is directed to the stimulation of the germination and growth of a seed or a plant, including seedlings, young planrs or any organ from which a plant can be generated, which involves the step of exposing the vegetabla matter, e.g., the seed or plant, and/or the 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 fertilizer-pesticide combinations having a thin layer of a carboxylated polymer coated thereon.

In addition, the process also relates to the intimate admi~
ing of fertilize, such as urea, ammonicsl, phosphorus and/or sulphur fertilizers, alone or combined with pesticides, with a seed or plant, or other vegetable matter, as defined herein, without damage to thè
same in a plant growth medium which involves the steps of:

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WO 92/17422 2 1 0 ~ ~ 8 8 PCT/US92/00045 1) admixing or otherwise contacting a fertilizer, pr~ferably in solid granular fo~m, having a thin ionically and covalently cross-linked sulfonated polymer and amine termina~ed polycaprolactone 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, it has been discovered that fertilizers with thin films or coatings of ionically and covalently crosslinked sul-fonated polymers and amine terminated polycaprolactones 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 fertilizer and fertilizer/pesticide combinations having thin films or coatings of ionically and covalently sulfonated polymer and amine terminated polycaprolactone have been found to be extremely effective in stimulating seedling emergence and early plant growth by permitting the placement of urea fertilizers with the seed at the time of planting. It has been tiscovered that the thin ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone film or coating slows the release of urea and ammonium to a sufficient extent to prevent burning of the seed or young seetling to which such a fertilizer is applied. In contrast to conventional slow release fertilizers, for example, urea coated with a thin film of ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone in accordance with the present invention can be applied to the plant growth media at a rate in excess of 25k&N/ha without raising the 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 in 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 of the ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone coated .' .

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W O 9~ 422 ~ 1 0 ~ 8 ~3 PCT/US92/~004s fertilizers and fertilizer/peseicide combination in accordance with the present invention. Thus, the carboxylated polymer coated fertilizsrs and fertilizer/pesticide combinations in accordance with the present invention have been found to be particularly adv~n~ageous in promotion of e~ergence, and early growth stimulation of seedlings, while per~itting placement of the fertilizer with the seed.

Although the coated fertilizer of the present invention has been found to be particularly advantageous in permitting the introduc-tion of nitrogen fertilizers ant fertilizer/pesticide co~binations simultaneously into the soil with the seed so as to stimulate emergence of seedlings and the growth of plants, fertili~ers coated in accordance with the present invention may also preferably contain a source of sulfur and phosphorous, in which case, the fertilizer may be applied so as to supply nitro~en at a rate in excess of 25kg/ha, sulfur in excsss of 15kg/ha, and phosphorous at a rate in excess of 30kg/ha without burning the seeds or preventing subsequent :emergence of the seedlings.

The present inve~tion, therefore, is particularly suitable for replacing split or multiple applications of uncoated fertilizers to ensure that the available plant nutrient matches the physiological need of the crop for the same. In this regard, plants do noe require all of their nitrogen at one time; for example, wheat requires over 35X of its nitrogen between booting and the soft touch stage.
Typically uncoated fertilizers are applied in split applications at key physiological plant growth stages such as tillering, stem elonga-tion, booting and seed filling to ensure that the nitrogen is avail-able to the plant as required. Controlled release nitrogen, there-fore, 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 combina-tions in accordance with the present invention are particularly suitable for introduction with the seed and/or into the plant growth median during a single agricultural step so as to eliminate thç need for post e~er~ence application of the fertilizer.

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W O 92tl~422 PCrtVS92~00045 210 168g The fertilizer and fertilizer/pesticide combination coated with thin films of ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone in accordancP with the present invention, however, may also be introduoed into the soil prior to a subcequent planting of the seeds. For example, the coated fertilizer of the present invention may be introduced into the soil in the Fall of a year prior to planting wheat in the Spring of the following year, without appreciable loss of nutrients. Thus the coated fertilize of the present invention may be formulated so as to supply nitrogen at a sufficient rate and timing of release to satisfy the physiological need for nitrogen of the wheat beginning in the Spring of the year when the wheat is sown through the growing season.
The coated fertilizer of tha present invention may also be applied in a single application to supply nitrogen at a rate and timing of release essentially the same as pro~ided by separate applications of fertilizer prescribed under a standard intensive cereal management program (ICM) thereby eliminating the need for multiple fertilizer applications which would otherwise be required by such an ICM program.

In view of the foregoing, it is believed that the ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone coating of fertilizers in accordance with the present invention, and particularly phosphate fertilizers, would effectively reduce the chemical immobilization of phosphorous as calcium or aluminum/ironphosphate, thereby making fertilizer phosphorous more plant available.

In accordance with the present inven~ion, fertilizers and fertilizer/pesticide combinations with thin films or coatings of ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone permits the fertilizer to be applied to the soil at a rate which is at least lOZ 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.
i . Althou~h the rate of fertilizer reduction may be as much as about 50%
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less than the fertilization rate otherw~se required, typically the . .

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W O 92tl7422 P~T/US92/00045 rate is reduced within the range of about 10-20% less than a conven-tional fertilization rate.

It has been discovered that fertilizers and fertilizer/pesti-cide combinations coated with thin films of ionically and covalently crosslinked sulfonated polymers and amine terminated polycaprolactone experience reduced nitrogen losses. ~his is particularly true for urea and ammonium sulfate. Conventionally, nitrogenous fertilizers added ~o moist soils, i.e., soils wherç 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 N20 and/or N2 gas, volatilization of ammonia gas, and immobilization into the active microbial biomass. It has been discovered that fertilizers coated with thin films of ionically and covalently crosslinked sulfonated polymers and amine terminated polycaprolactones in accordance with the present invention experience substantially reduced losses of nitrogen by controlling the release of nitrogen by the coated fertilizer; thus, the amount of fertilizer nitrogen available at any particular time which would be sub;ected to the previously mentioned deleterious effects is minimized. An advan-tage of the present invention, therefore, is a reduction in the losses of, for example, = onical nitrogen by chemical, physical and bio-; logical occurrences. Thus, the present invention has been fo~nd effective in increasing plant yields because more nitrogen is avail-able for the needs of the plant, while decreasing pollution of ground water with fertilizer-derived nitrates, decreasing destruction of the ;ozone layer of the atmosphere due to fertilizer-derived N20, and increasing residual nitrogen to benefit subsequent crops planted during the normal course of agricultural rotation.
;, Description of the Prefçrred Embodiments The following Examples illustrate the present invention without, however, limiting the same hereto.

.Unless otherwise specified, all measurements are in parts by we~ght per 100 parts of sulfonated polymer.
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W O 92/17422 2 ~ 0 ~ ~ 8 8 PCT/US92/00045 Exam~le 1 3.5 g (1 meq.) of a sulfonated EPDM (based on EPDM of 50Z
ethylene, 45X propylene and 5Z ENB, sulfonated with acetyl sulfate in situ, as described in U.S. Patent No. 4,221,712 and related cases, isolated in methanol as the acid form, and dried in a vacuum oven at -35-C), containing 29.0 meq. of sulfur per 100 g of poly~er, as determined by elemental analysis, was dissolved in 66.5 toluene overnight to give a 5.0 weight percent solution.

2.1 g (1 meq.) of an N,N-dimethyl-1,3-propane diamine termi-nated polycaprolactone, molecular weight 2,100 X N - 1.314 + .005% was dissolved in 18.9 g of toluene to give a 10.9 weight percent solution.
This solution was then added to the highly viscous EPDM polymer sulfonic acid solutLon prepared above.

Films were cast from the solution of neutralized polymer acid onto Teflon coated aluminum foil. The solvent was removed by evapora-tion at ambient conditions. The resultant films were a slightly hazy yellow and showed no visible signs of phase separation. The resulting films appeared to be tough and flexible, with no evidence in inco~-~ patibility.

; Thermal mechanical analysis conducted on the polymer sample revealed a ma~or transition at about -65C tEPDM Tg) and a second transition at about 38C, identified as the crystalline melting point for the polycaprolactone phase.

Example 2 3.5 g (1 meq.) of a sulfonated EPDM (similar to that of Example 1) sulfonated with acetyl sulfate in situ, isolated in methanol, as the acid form, and dried in a vacuum oven at 35C) containing 29.0 meq. of sulfur per 100 g of polymer, as determined by elemental microanalysis was dissolved in 66.5 g toluene overnight to give a 5.0 weight percent solution.

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was dissolved in 35.8 g toluene to give a 10.0 weight percent solu-tion. This solutlon was added to the h~ghly viscous EPDM polymer sulfonic acid solution prepared above.

Films were cast from the final solution of the neutralized polymer acid using Teflon coated aluminum foil pans as the substrate.
The solvent was remo~ed by evaporation at a~bient temperature. These films did not phase separate, but were h3zier and stiffer than those prepared under Example 1.

Example 3 The following example will demonstrate the performance of the coating of ionomer and amine terminated caprolactone complex.
, Two polymer coating systems were prepared in 97.5/2.5 toluene-methanol solvent. Polymer coating system A contains 2 weight percent zinc sulfo EPD~ (ZSE-25) and poly-4-caprolactone 3-dimethyl . amino.propylamine (molecular weight - 1,000) at 9/1 ratio of the former to the latter. Polymer coat~ng system B also contains 2 weight percent of zinc sulfo EPDM (ZSE-25) and poly-~-caprolactone 3-dimethyl amino propylamine, but with the molecular weight of the latter of about 6,000; also at similar 9/1 ratio of the former to the latter.
These solutions were used for cast coating of the film of this instant invention over solid, dry urea samples in order to determine the barrier properties of the encapsulated urea to water extraction.

To determine barrier properties of films formed from solu-tion, urea slides were coated for immersion tests. The procedures for preparing coated samples of urea slides and conducting immersion tests -are described below.

Urea samples were prepared by depositing reagent grade urea (Fisher Scientific) over microscope glass slides. This was done by ; dippin~ glass slides into molten urea at a temperature of about :., W O 9~/17422 2 1 0 4 6 8 8 PCT/US92/00045 135-145-C, followed by cooling and solidificstion of the urea layer.
The urea layer was built up to about 7 mm 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 ehose described above, followed by drying in a vacuum oven at 70C ~or about 3 hours.
The dipplng and drying cycles were repeated until the film thicknesses shown in Table I were obtained.

The barrier properties of the various polymeric films were determined by immersion of each coated urea slide in abo~t 100 g of deionized water at room temperature. The amount of urea released into the water was determined by recovering the urea after evaporating the water. Each sample was initially immersed for 1 day, followed by immersion in fresh water for 3 days and for weekly intervals there-after.
.
Table I shows the permeabilities of urea solution extracted from the coated slides which were immersed in water at room tempera-ture. The permeabilities of the coating materials were determined by applying Fick's law of diffusion at steady state. Fick's law states that:
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Jm ~ D~ ~C
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where Jm ~ mass flux (loss) through the film or membrane, A - trans-port area, QC - concentration gradient, ~ ~ f$1m or membrane thickness and D - membrane diffusivity constant which is equal to the ratio of permeability (P) over the solubility ratio (K) of urea in the membrane and in water.
.
The performance of the ionomer coatings was compared wieh that of two commercially used coatin~ ~erials. The first commercial coating solution was a tung oil solu. by Fo~oy of ~ississippi at 30 weight percent solids in petroieum distillate. The second . commercial co~ting solution was linseed oil modified polyurethane Type ~' :

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~ , : ~ ' ', ~ , W O 92~1742~ `2 ~ 8 PCT/VS92/00045 I ~ade by Minwax Paint Co. of New Jersey at 45X solids in petroleum distillate. The two com~ercial coatings were cured at 70C for 48 hours after coating.

The permeability of urea solution through the ionomer films was found to be about ~ orders of magnitude lower than either that of tung oil or that of polyurethane. Tung oil and polyurethane were disclosed as release control coatings for water soluble fertilizers in U.S. Patent Nos. 3,321,298 and 3,233,518.

The reason for scatter in the permeability data for ionomer coatings shown in Table I is believed to be a result of the coating quality. Existence of pin holes will increase the apparent perme-sbility as calculated above. One should, therefore, assu~e that the lowest number corresponds to a more perfect coating. Permeabilities for the other poly~ers in Table I do, on the other hand, agree with literature data for perfect coatings.

This Example shows that encapsulated urea having a coating of the instant invention is more resistant to water extraction than the urea encapsulated by commercially used coatings. One can, therefore, apply a thinner coating of the ionomer and amine terminated ~-caprol-actone for equivalent results to obtain a cost advantage of the coating of the instant invention can be useful for a slower release until microbial degradation takes place for complete release of the urea. `

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TABLE I

Film Permeability Sample CoatingThickness (P-DK) N~ber MaterialMicrons cm2sec 141-3 ~ung Oil 75 4.3 x 10-9 141-6 Tung Oil 125 7.6 x 10-9 158-4 Polyurethane100 1.3 x 10-9 158-5 Polyurethane40 2.1 x 10-9 157-3 Polymer Coatlng 20 6 x 10-10 System A
157-4 Polymer Coating 30 1.8 x 15-9 System B

Exam~le 4 Fluidized Bed Process for SEPDM and Polvcaprolactone Coatin~

The SEPDM and polycaprolactone coated fertilizer granules are protuced USiDg the following procedure:

4 kg of 2 to 3 mm fertilizer granules are introduced into a fluid bed c~ating machine, including a Uurster insert, manufactured by Glatt Air Techniques Inc., motel number GPCG-5. The fertilizer is fluidized by blowing 130 scfm of heated air (45C) through bed. After the bed reaches a temperature of 30-C, a 1.25 weight percent solution of the SEPDM polymer containing N,N-dimethyl-l, 3-propane diamine terminated polycaprolactone in toluene and methanol cosolvent is sprayed onto the fertilizer granules at the Uurster insert entrance.
The spray nozzle uses a commercial two fluid nozzle using air at 3 bars pressure to form an atomized spray regime in the Uurster insert.
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The spraying is continued at 40 gm/min rate until the -;~required thickness of polymeric coating is built up on the fertilizer, ~ .
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W ~ 92/17422 ~ PCT/US92/00045 i.e. approximately 80 minutes per a coating level of 1 weX polymer on the fertil~zer.

After the solution is sprayed onto the granules in the Wurster insert, the thus coated granules are blown by the heated sir upwsrds into they drying section of the machine. Here, the solvents are evaporated by the hot stream, leaving a thin coat of dried polymeric material on the granules. The dried granules fall back into the fluid bed and ~hen re-enter the Wurster insert where the coating process is repeated. Thus, multiple films or layers of the polymeric coating is built up until the spraying was stopped.

The spraying is continued until 2 wtX of polymer is added.
The spraying is stopped and the coated granules are dried with the hot air for S minutes.

Example S

The contemplated method for crosslinking the polymer using electron beams is as follows:

Granular fertillzer pellets in the size range of 2 to 3 mm coated with 2 wt.~ per zinc sulfonated EPDM and amine terminated polycaprolactone is placed in a monolayer on a flat bed cart. The cart is placed in an electron beam generator until a dose of 10 M~garads is obtained.

Example~

The contemplated method for crosslinking zinc sulfonated EPDM
terpolymer and N-N dimethyl-l, 3-propane diamine terminated poly-caprolactone with sulfurmonochloride is as follows:

Approximately 100 g of coated pellets consisting of 2 wt.Z
zinc sulfonated EPDM terpolymer and N-N dimethyl-l, 3-propane diamine terminated polycaprolactone on 2-3 mm granular fertilizer are placed in a monolayer in a flat dish. The dish is then put into a desiccator : . : ., : . .. ..
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W O 92~17422 2 1 0 ~ ~ 8 8 PCT/US92/00045 which contains a separate is which contained sulfur monochloride. The d~ciccator is closed and evacuated so that only sulfur monochloride vapor remains. The psllets were left in the desiccator for 24 hours.
After that they are rsmoved and placed in a vacuum oven at 40-C for 10 to 12 hours in order to remove resldual sulfur monochloride.

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Claims (3)

PCT/US92/0??945 CLAIMS:

1. An encapsulated water soluble material comprising (i) a substrate and (ii) a polymeric film of about 1 to about 100 micro-meters on adhering to at least one surface of said substrate, said polymeric film comprising an ionically and covalently crosslinked sulfonated polymer having about 10 to about 200 meq of sulfonate groups per 100 grams of said crosslinked sulfonated polymer, said sulfonate groups being neutralized with a polycaprolactone polymer being characterized by the formula:

wherein R1 or R2 is an alkyl, cycloalkyl or aryl group: R3, R4 and R5 are a hydrogen or alkyl, cycloalkyl, or aryl group; m equals 1 to 20 and n equals 1 to 500.

2. The encapsulated water soluble material of claim 1 wherein the polymeric film is about 2-40 micrometers thick and the sulfonate groups are complexed with a metal ion capable of coordinat-ing with the amino group of the caprolactone polymer.

3. The encapsulated material of claim 1 wherein the sub-strate is a fertilizer.