WO1992017422A1

WO1992017422A1 - Ionically and covalently crosslinked biodegradable barrier films of ionomer polymer

Info

Publication number: WO1992017422A1
Application number: PCT/US1992/000045
Authority: WO
Inventors: Pacifico V. Nanalastas; Evelyn N. Drake; Warren A. Thaler; Edward N. Kresge; Chester W. Elspass; Vijay Swarup; Albert J. Geiger
Original assignee: Exxon Research And Engineering Company
Priority date: 1991-03-28
Filing date: 1992-01-03
Publication date: 1992-10-15
Also published as: CA2104688A1; NO933437L; EP0577627A1; EP0577627A4; NO933437D0

Abstract

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

lONICALLY AND COVALENTLY CROSSLINKED BIODEGRADABLE 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 comprises a polymeric film of about 1 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 the formula

Rl R R3 0

\ I I I

N-(C)_mNC(CH₂)5[0C(CH₂)5]n-l0H

/ I I R2 R5 O

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

The present invention relates to controlled release materials, e.g., fertilizers, micronutrients, herbicides, pesticides, and particularly to fertilizer-pesticide compositions. The invention is more particularly directed to fertilizers and fertilizer-pesticide compositions to which thin film or ultrathin films or coatings of ionically and covalently crosslinked sulfonated polymers and a ine terminated polycaprolactone have been applied as an improved con¬ trolled release agent. Related to this, the present invention is directed to methods for producing 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, agricultural processes in which the fertilizer and fertilizer-pesticide composites coated with ionically and covalently crosslinked sulfonated polymers and amine terminated polycaprolactone in accordance with the present invention may be applied include processes for enhancing vegetation including plant growth stimulation and regulation as well as stimulation of seed germination.

Background of the Invention

The present invention relates to the compositions of associ¬ ating polymer protective barrier films, which will protect materials, such as agricultural chemicals, for a period of time and then degrade and release the encapsulated contents to the environment. More specifically, this invention relates to the preparation of ionomer compositions containing compatibilized 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 degrading 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 polymeric systems capable of degrading to a crumbly friable mass. These systems are based on the ability to produce compatible polymeric films from ionically and covalently crosslinked sulfonated polymers and amine terminated poly¬ caprolactone. The ionically and covalently crosslinked sulfonated polymer can be in the free acid form or neutralized with a metal which can coordinate with the amine. The combination 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, susceptibility to biodegradation. The advent of plastics has introduced improved methods of packing goods. For example, polyethylene and polypropylene films, bags and bottles and polystyrene foam cups have the advantages of being chemically resistant, mechanically tough, light in weight and inexpensive. However, the increasing use of plastics in packaging has led to the appearance of such materials in litter. While littered plastic articles are no more objectionable than littered articles of other materials, such as paper objects and metal cans, it has been 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 suggested. 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 polymer by copolymerization of a common monomer with a second monomer processing such groups; 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. 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 metal compound 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 polymers 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 use 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 soil to ensure maximum plant yield. The amount and form of the fertilizer added are pre-determined by chemi¬ cally 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 fertilizer is added in amounts 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 of example, may be applied as solid granules or in liquid form. These primary fertilizers may be supplemented with certain micronutrient trace elements such as copper, iron, manganese, zincj cobalt, molybdenum, boron usually supplied as oxides or salts containing the elements in the cationic form. Suitable salts are, for example, sulphates, nitrates, chlorides, molybdates or borates. The difference 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 fertilizers added to the soil 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 50%. 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 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 rapidly immobilized resulting in fertilizer use efficiencies seldom exceeding 30%.

If the release of nutrients from fertilizers could be con¬ trolled 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 ground- waters thus minimizing ground-water pollution; and/or

iv) less nitrogenous gases would evolve into the atmosphere thus minimizing damage to the fragile ozone layer.

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 coating materials, this technology has not been applied in accordance with the present invention, parti¬ cularly with 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 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 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 ionomers containing associating ionic groups can further improve the strength and barrier performance of these 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 suitable for application to agricultural products, such as fertilizers, pesti¬ cides, herbicides, insecticides, bacteriocides, fungicides, nemati- cide, sporicides, and the like, in addition to combinations thereof.

Summary of the Invention

The present invention relates to a process 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 environment.

In general, the present invention also relates to coating vegetation enhancement agents, such as fertilizers and fertilizer- pesticide combinations, with thin or ultra-thin coatings of ionically and covalently 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 involving methods of using ferti¬ lizers and fertilizer-pesticide combinations coated with ionically and covalently crosslinked sulfonated polymers with amine terminated polycaprolactone in accordance with the present invention 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 Description of the Invention

The thin polymeric coatings 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 crosslinking agent which is not activated until a temperature of 40"C is obtained; coating the organic solution of the water insoluble sulfonated polymer and an amine terminated polycaprolactone and the crosslinking 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 alternative process comprises coating an organic solution of the water insoluble sulfonated polymer and amine terminated polycaprolactone onto the substrate and subsequently subjecting the coated substrate to an election beam thereby covalently crosslinking the water insoluble sulfonated polymer. A still alternative process comprises coating a substrate with an organic solution of water insoluble sulfonated polymer and amine terminated polycaprolactone and subsequently con¬ tacting the coated substrate 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 used to crosslink the water insoluble sulfonated polymer and amine terminated polycaprolactone. It is 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. The polymeric films of the instant invention are formed from a compatible mixture of a ionically and covalently crosslinked sulfon¬ ated 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 this present invention are derived from elastomeric polymers wherein the elastomeric polymers are derived from unsaturated 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 30% by weight of a conjugated multiolefin having from about 4 to 14 carbon atoms, e.g., isoprene. The resulting copolymer contains 85% to 99.8% by weight of combined isoolefin and 0.2% to 15% 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 100,000 to about 400,000 and a Wijs Iodine No. of about 0.5 to 50, preferably 1 to 15.

For the purposes of this invention, the Butyl rubber may have incorporated therein from about 0.2% to 1.0% of combined multiolefin, preferably about 0.5% to about 6%, more preferably about 1% to about 4%, e.g., 2%.

Illustrative 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 and a mole percent unsaturation of about 1% to about 5% may be sul¬ fonated to produce the polymers useful in this invention. Preferably, these polymers have 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 according to the definition as found in ASTM-D-1418-64 and is intended to mean terpolymers containing ethylene and propylene in the backbone and a diene in the side chain. The preferred polymers contain about 40 to about 75 weight percent ethylene and about 1 to about 10 weight percent of a diene monomer, the balance of the polymer being propylene. Preferably, the polymer contains 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 nonconjugated diene monomers which may be used in the terpolymer (EPDM) are 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-propenyl-2- norbornene, and methyl tetrahydroindene.

A typical EPDM is Vistalon 2504 (Exxon Chemical Company) , a terpol mer having a Mooney viscosity (ML, 1 + 8, 212^βF) 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 Mn as measured by GPC of Vistalon 2504 is about 47,000, the Mv as measured by GPC is about 145,000 and the M as measured by GPC is about 174,000.

Another EPDM terpolymer, Vistalon 2504-20, is derived from Vistalon 2504 (Exxon Chemical Company) by a controlled extrusion process, wherein the resultant Mooney viscosity at 212^βF is about 20. The Mn as measured by GPC of Vistalon 2504-20 is about 26,000, the Mv as measured by GPC is about 90,000 and the Mw as measured by GPC is about 125,000.

Nordel 1320 (DuPont) is another terpolymer having a Mooney viscosity at 212^βF 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 (Mn) as measured by GPC of about 10,000 to about 200,000, more preferably of about 15,000 to about 100,000, most preferably of about 20,000 to about 60,000. The Mooney viscosity (ML, 1 + 8, 212'F) of the EPDM terpolymer is about 5 to about 60, more preferably about 10 to about 50, most preferably about 15 to about 40. The Mv as measured by GPC of the EPDM terpolymer is preferably below about 350,000 and more preferably below about 300,000. The Mw 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 -100^βC to about 100°C for a period of time of about 1 to about 60 minutes, most preferably at room temperature for about 5 to about 45 minutes; and most preferably about 15 to about 30. These sulfonating agents are selected from an acyl sulfate, a mixture of sulfuric acid and an acid anhydride or a complex of a sulfur trioxide donor and a Lewis base containing oxygen, sulfur or phos¬ phorous. Typical sulfur trioxide donors are SO3, chlorosulfonic acid, fluorosulfonic acid, sulfuric acid, oleum, etc. Typical Lewis bases are dioxane, tetrahydrofuran, tetrahydrothiophene or triethyl phos¬ phate. The most preferred sulfonation agent 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 determined 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. Hydrolytically stable means that the acid function, in this case the sulfonic acid, will not be eliminated under neutral or slightly basic conditions to a neutral moiety which is incapable of being converted to highly ionic functionality.

Neutralization of the unneutralized sulfonated polymer can be accomplished by 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 polymers are formed by the reaction of e-caprolactone with an organic diamine in the presence of a catalyst 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 solvent at a temperature of about 50 to about 200^βC, more preferably about 75 to about 180^*C and most preferably about 90 to about 100°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:

catalyst

e-caprolactone

Rl R4 R3 0

\ I I I

N(C)_nNC(CH₂)5[OC(CH₂)5]n-lOH

/ I II R2 R50

wherein n - 1 to 500; m - 1 to 20; Rj 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 atoms, and aryl groups; R3 is selected from 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 R5 are hydrogen, alkyl, cycloalkyl or aryl groups. Typical but nonlimiting examples, of useful diamines are:

CH₃

) NCH2CH2CH2NH2 CH3 '

CH3.

) NCH2CH2CH2NH

CH3 ' I

CH3

) NCH2CH2CH2CH2CH2CH2NH2 CH3 '

H

/ CH3N CH2CH2NH2

CH3

) N CH2 _nNH2 where n > 1 CH3 '

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 Polymerization: Ring Opening Polymerization, edited by Frisch and Rugen, published by Marcell Dekker in 1969, wherein stannous octanoate is an especially preferred catalyst. The catalyst is added to the reaction mixture at a concentration level of about 100 to about 10,000 parts of catalyst per one million parts of e-caprolactone.

The resultant polycaprolactone polymer has an Mn 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 melting point from below room temperature to about 55^*C, more prefer¬ ably about 20*C to about 52^βC, and most preferably about 20^βC to about 50^βC.

The 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 viscosity 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 sulfonated 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.

The preferential plasticizer is incorporated into the neu¬ tralized sulfonated polymer at less than about 60 parts by weight per 100 parts of the sulfonated polymer, more preferably at about 5 to about 40, and most preferably about 7 to about 25. Alternatively, 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.

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 amine terminated caprolactone (e.g., poly-e caprolactone 3-dimethyl amino propylamine) over a substrate at ambient temperature or at 10-70^βC by either dip-coating or spray-coating or with the use of other techniques for thin spreading (such as brushing) . The organic solution can be prepared by mixing a proportionate weight of about 1-10% ZSE-25 with 1-10% poly-e caprolactone 3-dimethyl amino propyl¬ amine, both in Solvent A. Solvent A comprises 85-97.5% toluene or other appropriate hydrocarbon and 15-2.5% or other alcohol. The organic solvent 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 20°C and 100"C. The most preferred temperature of the drying gas should be about 70°C for fast evaporation of the organic solvent system. After drying the thickness of the applied film or coating should be about 1 to about 100 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 instant invention 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 10-70°C, but at a temperature lower than the activation temperature of the covalent crosslinking agent, by either dip coating or spray-coating or with the sue of other techniques for thin spreading (such as brushing) . The organic solvent system is then permitted to evaporate with or without 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 of the drying gas is between 20"C to 100"C. The most preferred temperature of the drying 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 percent. 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 polymer 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 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 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 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, clay, EVA copolymer masterbatch, EPDM-masterbatch, silicone oil, plasticizer as well as organic solvents.

Accelerators are contemplated to include thiazoles, sulfin- amides, thiurams, dithiocarbamates, guanidines and thioureas,

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

The concentration of the covalent crosslinking agent in the organic solution or carrier is about 0.1 to about 20 weight percent, more preferably about 0.15 to about 15 weight percent and most prefer¬ ably about 0.17 to about 10 weight percent. The curing of the coating of the carboxylated 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 and amine terminated polycaprolactone coating is cured by exposure to an electron beam radiation at ambient tempera¬ ture for a sufficient period of time (10 to 60 minutes) to cause covalent crosslinking, wherein the electron beam is 1 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 used to crosslink the coating. In a first embodiment, the substrate particles coated with dried sulfonated polymer and amine terminated polycaprolactone coating is covalently crosslinked by exposing the coated particles to a saturated vapor or sulfur monochloride at ambient temperature for a sufficient period of time, 1 hour to 48 hours, more preferably 2 to 36, and most preferably 10 to 30, to cause 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 crosslinked by contact with 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, more 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 sulfonated 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 weight 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 desired 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: MACRONUTRIENTS

Nitrogen, for example provided by: Ammonium sulphate Ammonium chloride Ammonium nitrate Diammoniu phosphate Ammonium phosphate nitrate Monoammonium phosphate Ammonium phosphate sulphate Sodium nitrate Potassium nitrate Calcium nitrate Urea Ammonium nitrate-calcium carbonate mixture

Potassium, for example provided by: Potassium nitrate Sulphate of potash Muriate 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 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 tetraborate-pentaborate Colemanite

Copper as:

Cupric oxide

Curous oxide

Cupric sulphate nonanhydrate

Ferrous sulphate heptahydrate Manganese as:

Manganous carbonate Manganous oxide Manganous-manganic oxide Manganous sulphate monohydrate

Molybdenum 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 ammonium

Crotonylidene diurea phosphate (Mag Amp)

Urea formaldehyde Guanyl urea sulphate

Trimeth lene tetraurea (GUS)

Oxamide Guanyl urea phosphate

Cyanuric acid (GUP)

Ammeline Thiourea

Ammedlide Phenylurea

Urease or nitrification 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) . 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 herbicides such as triallate and trifluralin, 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-dieth lk 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 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 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: cereals such as wheat, maize (corn), rice, barley, 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 polymers 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 the fertilizer is intended. The previously listed fertilizers and pesticides, either individually and/or in mixtures, may be coated with ionically and covalently crosslinked sulfonated polymers in accordance 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 release 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 inhibitors 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 and amine terminated polycaprolactone in accordance with the present invention may be mixed with non-coated fertilizers and/or pesticides of the same or different composition. In this regard, the non-coated member may be selected from the group consisting of macronutrients, 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 as 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 crosslinked sulfonated polymer and amine terminated polycaprolactone in accordance with the present invention may comprise 5 to 95% by total weight of the mixture or the non-coated vegetation enhancement agent may comprise 5 to 95% by total weight of the mixture.

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 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. Examples include: fertilizers, micro¬ nutrients, coated 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, having a dimension, and preferably a major dimension, within the range of about 1.0 to 10.0 mm. Preferably, the fertilizer particles are granules having a diameter within the range of about 1.0 to 6.0 mm and most preferably about 1.0 to about 3.5 mm. Commercial fertilizer granules typically have a diameter of about 2.3 mm, although particles, such as granules having 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 may 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 release coating, to which additional applications of the covalently crosslinked sulfonated polymer and amine terminated polycaprolactone films or coatings in accordance with the present invention may be applied. Thus, a multiple-coated fertilizer or fertilizer/pesticide combination may be produced in accordance with the present invention. 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 plants or any organ from which a plant can be generated, which involves the step of exposing the vegetable 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 admix¬ ing of fertilize, such as urea, ammonical, 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 the same in a plant growth medium which involves the steps of: 1) admixing or otherwise contacting a fertilizer, preferably in solid granular form, having a thin ionically and covalently cross¬ linked sulfonated polymer and amine terminated 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 discovered 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 seedling 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 25kgN/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 fertilizers and fertilizer/pesticide combination in accordance with the present invention. Thus, the carboxylated polymer coated fertilizers and fertilizer/pesticide combinations in accordance with the present invention have been found to be particularly advantageous in promotion 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 particularly advantageous in permitting the introduc¬ tion of nitrogen fertilizers and fertilizer/pesticide combinations simultaneously into the soil with the seed so as to stimulate emergence of seedlings and the growth of plants, fertilizers 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 nitrogen at a rate in excess of 25kg/ha, sulfur in excess 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 invention, 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 not require all of their nitrogen at one time; for example, wheat requires over 35% 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 the need for post emergence application of the fertilizer. The fertilizer and fertilizer/pesticide combination coated with thin films of ionically and covalently crosslinked sulfonated polymer and amine terminated polycaprolactone in accordance with the present 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 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 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 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 invention, 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 10% 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 rate of fertilizer reduction may be as much as about 50% less than the fertilization rate otherwise required, typically the 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. This is particularly true for urea and ammonium sulfate. Conventionally, nitrogenous fertilizers added to moist 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 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 subjected 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, ammonical nitrogen by chemical, physical and bio¬ logical occurrences. Thus, the present invention has been found 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 N2O, and increasing residual nitrogen to benefit subsequent crops planted during the normal course of agricultural rotation.

Description of the Preferred Embodiments

The following Examples illustrate the present invention without, however, limiting the same hereto.

Unless otherwise specified, all measurements are in parts by weight per 100 parts of sulfonated polymer. Example 1

3.5 g (1 meq.) of a sulfonated EPDM (based on EPDM of 50% ethylene, 45% propylene and 5% 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^βC), containing 29.0 meq. of sulfur per 100 g of polymer, 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 % 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 solution 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 incom¬ patibility.

Thermal mechanical analysis conducted on the polymer sample revealed a major transition at about -65°C (EPDM Tg) and a second transition at about 38*C, 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 35°C) 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. 3.98 g (1 meq.) of an N,N-dimethyl-1,3- propane diamine terminated polycaprolactone molecular weight 3,980 % N - 0.682 + .003% was dissolved in 35.8 g toluene to give a 10.0 weight percent solu¬ tion. This solution was added to the highly 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 removed by evaporation at ambient temperature. These films did not phase separate, but were hazier 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 EPDM (ZSE-25) and poly-e-caprolactone 3-dimethyl amino propylamine (molecular weight = 1,000) at 9/1 ratio of the former to the latter. Polymer coating system B also contains 2 weight percent of zinc sulfo EPDM (ZSE-25) and poly-e-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 dipping glass slides into molten urea at a temperature of about 135-145*C, followed by cooling and solidification 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 those described above, followed by drying in a vacuum oven at 70°C for abβut 3 hours. The dipping 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 about 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. Pick's law states that:

J_m - DA AC

where J - mass flux (loss) through the film or membrane, A - trans¬ port area, ΔC - concentration gradient, 8 - film 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 with that of two commercially used coating materials. The first commercial coating solution was a tung oil solution made by Formby of Mississippi at 30 weight percent solids in petroleum distillate. The second commercial coating solution was linseed oil modified polyurethane Type I made by Minwax Paint Co. of New Jersey at 45% solids in petroleum distillate. The two commercial coatings were cured at 70°C for 48 hours after coating.

The permeability of urea solution through the ionomer films was found to be about 2 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¬ ability 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 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 ϋ-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.

TABLE I

The SEPDM and polycaprolactone coated fertilizer granules are produced using the following procedure:

4 kg of 2 to 3 mm fertilizer granules are introduced into a fluid bed coating machine, including a Wurster insert, manufactured by Glatt Air Techniques Inc., model number GPCG-5. The fertilizer is fluidized by blowing 130 scfm of heated air (45^βC) through bed. After the bed reaches a temperature of 30^βC, 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 Wurster 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 Wurster insert.

The spraying is continued at 40 gm/min rate until the required thickness of polymeric coating is built up on the fertilizer, i.e. approximately 80 minutes per a coating level of 1 wt% polymer on the fertilizer.

After the solution is sprayed onto the granules in the Wurster insert, the thus coated granules are blown by the heated air upwards 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 then 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 wt% of polymer is added. The spraying is stopped and the coated granules are dried with the hot air for 5 minutes.

Example 5

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 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 Megarads is obtained.

Example 6

The contemplated method for crosslinking zinc sulfonated EPDM terpolymer and N-N dimethyl-1, 3-propane diamine terminated poly¬ caprolactone with sulfurmonochloride is as follows:

Approximately 100 g of coated pellets consisting of 2 wt.% zinc sulfonated EPDM terpolymer and N-N dimethyl-1, 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 which contains a separate is which contained sulfur monochloride. The desiccator is closed and evacuated so that only sulfur monochloride vapor remains. The pellets were left in the desiccator for 24 hours. After that they are removed and placed in a vacuum oven at 40"C for 10 to 12 hours in order to remove residual sulfur monochloride.

Claims

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 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 the formula:

Rl R4 R3 0

\ I I I

N-(C)_mNC(CH₂)5[OC(CH₂)5]n-lOH

/ I II R2 R5 0

wherein Rl or 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.

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.

4. The encapsulated material of claim 1 wherein the sub¬ strate is a nutrient.

5. The encapsulated material of claim 1 wherein the sub¬ strate is a pesticide.

6. The encapsulated material of claim 1 wherein the sub¬ strate is a herbicide.