EP1073693A1 - Coprecipitation of cellulose esters with functional additives and compositions thus obtainable - Google Patents

Coprecipitation of cellulose esters with functional additives and compositions thus obtainable

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Publication number
EP1073693A1
EP1073693A1 EP99916652A EP99916652A EP1073693A1 EP 1073693 A1 EP1073693 A1 EP 1073693A1 EP 99916652 A EP99916652 A EP 99916652A EP 99916652 A EP99916652 A EP 99916652A EP 1073693 A1 EP1073693 A1 EP 1073693A1
Authority
EP
European Patent Office
Prior art keywords
acid
additive
cellulose ester
cellulose
weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99916652A
Other languages
German (de)
French (fr)
Inventor
Kevin Joseph Edgar
Eric Eugene Ellery
Ricky Joseph Offerman
Richard Johnson Brewer
Gregory Andrew Kramer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Chemical Co
Original Assignee
Eastman Chemical Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Chemical Co filed Critical Eastman Chemical Co
Publication of EP1073693A1 publication Critical patent/EP1073693A1/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/08—Cellulose derivatives
    • C08L1/10—Esters of organic acids, i.e. acylates
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/08—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests containing solids as carriers or diluents
    • A01N25/10—Macromolecular compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
    • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
    • A61K9/1605—Excipients; Inactive ingredients
    • A61K9/1629—Organic macromolecular compounds
    • A61K9/1652—Polysaccharides, e.g. alginate, cellulose derivatives; Cyclodextrin

Definitions

  • the invention relates to new methods for combining a cellulose ester with a functional additive to produce a plastic or a controlled release matrix system and method of using the system.
  • Cellulose esters precipitated as a dry powder or flake have been compounded with other materials by thermo-mechanical processes.
  • Cellulose esters may also be mixed with other additives by dissolving the precipitated ester in a solvent, dispersing the additives in the resulting dope, and drying away or extracting the solvent.
  • One common method is to mix the cellulose ester with measured amounts of plasticizer, dye or pigment, and acid and/or UV light stabilizers in sigma blade mixers. The resulting admixture is then kneaded on a two roll mill with heat applied to compound the material into a homogeneous mixture, a compounded cellulosic plastic. A single screw extruder barrel with the appropriate feeder may take the place of the two roll mill.
  • twin screw extruder Another option for compounding cellulosic plastics involves the use of a twin screw extruder.
  • cellulose esters such as powders, flakes or pellets are fed into the extruder barrel along with the chemical additives.
  • the materials progress through various stages, which provide the necessary mixing, kneading, and heat required to compound the cellulosic plastic.
  • Materials other than monomeric plasticizers may be compounded with cellulose esters by use of twin screw extruders.
  • U.S. Patent No. 1,910,948 to Dreyfus teaches compounding a moldable cellulose derivative (cellulose acetate) with common cellulose acetate plasticizers, such as triacetin, alkyl sulfonamides and triphenyl phosphate, by use of a mixture of cellulose acetate powder with the plasticizer and a non-solvent for cellulose acetate, such as benzene, water and alcohol or mixtures of these.
  • the purpose of the non-solvent is to aid in the dispersion of the cellulosic plasticizer.
  • the non- solvent was dried away prior to molding of the plasticized powder. This compounding method provided a homogeneous moldable mixture without the application of heat in compounding.
  • U.S. Patent No. 4,282,209 to Tocker discloses a process for preparing an insecticide-polymer particle. The process involves combining a polymer, an insecticide, and an organic solvent to generate an admixture, and adding the admixture to a non-solvent in order to precipitate the insecticide-polymer particle.
  • the preferred organic solvent is a halogenated aliphatic and the preferred non- solvent is a hydrocarbon.
  • Numerous techniques have been described for preparing microcapsule shells surrounding a core have been reported.
  • British Patent 1,297,476 discloses a process for preparing a microcapsule containing a hydrophobic or hydrophilic core and polymeric shell material. The process involves admixing a cellulose ester, a core material and a glycol and adding the resultant mixture to water to produce droplets of the encapsulated core material.
  • US patent 3,796,669 reports on the use of a urea-formaldehyde polymer as an encapsulating agent with the polymer being formed in solution, encapsulating the target material.
  • US patents 5,225,278 and 5,277,979 Kielbania, Jr., et al. describe a technique for encapsulating materials by forming a polymer shell around a core phase by polymerizing a reactive compound containing at least two active methylene functional groups per molecule with a compound containing a methylene reactive crosslinking site.
  • Lo in US Patent 5,725,869 describes the preparation of microspheres from ethylcellulose by evaporation of an organic solvent from an emulsion of the polymer, an organic solvent and plasticzer from an aqueous solution containing an emulsifying agent.
  • the spheres described by Lo were reported to be spongy and porous, unlike the previously reported hard polymer shells.
  • These microspheres may include a material for later release when they are prepared or they may be prepared as "blank" spheres that can be used to absorb an active at a later time.
  • WO 99/00013 describes the inco ⁇ oration of agricultural actives into polymer matrices in the form of microparticles and subsequent controlled release into crops.
  • the microparticles described are reported to be different than "microcapsules" in which a polymer shell surrounds a liquid or solid core that contains an active.
  • the particles are said to be solid be solid throughout and that the active is distributed throughout the matrix material.
  • the prior art also discloses controlled release particles, wherein the additive is released due to the hydrolytic or thermal degradation of the particle.
  • European Patent Application No. 0 126 827 to Lewis et al. discloses a controlled release particle containing a biological additive to aquatic plants.
  • solvent compounding is the acetone spinning of cellulose acetate fibers.
  • the cellulose acetate is dissolved in acetone and dyes or pigments, or textile modifiers are added.
  • the solution is then spun and the acetone solvent is either dried or extracted from the resulting fiber by an acetone and water co-solvent mixture.
  • the invention relates to a process for blending a cellulose ester with a functional additive, comprising: (a) admixing the functional additive with the cellulose ester and a first acid; and
  • this invention relates to a process for blending a cellulose ester with a functional additive, comprising:
  • a functional additive comprising a plasticizer, another polymer, a UV light stabilizer, a dye, a pigment, an acid stabilizer, a flame retardant, an agricultural chemical, bioactive compound or a mixture thereof;
  • a cellulose ester comprising cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate, or a mixture thereof;
  • a first acid comprising acetic acid, propionic acid, butyric acid or a mixture thereof;
  • This invention also relates to a process for preparing a cellulose ester/functional additive blend, comprising:
  • step (b) depositing the admixture of step (a) in a pelleter
  • step (d) immediately after step (c) or simultaneous with step (c), contacting the extruded admixture with a precipitating agent to precipitate the cellulose ester/functional additive to thereby produce an extrusion of the cellulose ester/functional additive blend;
  • This invention further relates to a process for preparing a controlled release matrix system, comprising:
  • this invention relates to a method for controlled release of an agricultural additive comprising dispensing the controlled release matrix system, further comprising:
  • components (a) and (b) form a controlled release matrix system
  • This invention also relates to a method for controlled release of a pharmaceutical additive in the proximity of a target for the additive, comprising dispensing the controlled release matrix system, comprising:
  • components (a) and (b) form a controlled release matrix system
  • this invention further relates to a controlled release matrix system, comprising a homogeneous mixture of:
  • components (a) and (b) form a controlled release matrix system.
  • This invention further relates to a controlled release matrix system, consisting essentially of a homogeneous mixture of:
  • components (a) and (b) form a controlled release matrix system.
  • This invention provides for an efficient method of preparing cellulose ester blends that contain functional additives. It also provides a controlled release matrix system than can release a functional additive.
  • the term "functional additive” as used herein refers to cellulosic plastic modifiers. These modifiers can include, but are not limited to, plasticizers, other polymers, UV light stabilizers, dyes and pigments, acid stabilizers, agricultural chemicals, and bioactive compounds.
  • the polyesters After melt and/or solid phase polycondensation the polyesters have an inherent viscosity (IN.) of about 0.65 to about 1.2 dL/g, preferably 0.75 dL/g measured at 25°C in a 60/40 ratio by weight of phenol/tetrachloroethane.
  • I. inherent viscosity
  • the polyesters of this invention are preferably polyesters.
  • the polyesters of this invention can be any polyester known in the art, but is preferably an aliphatic polyester, or an aromatic- aliphatic copolyester, and more preferably an aliphatic polyester.
  • the polyesters of this invention may be miscible, partially miscible, or immiscible in certain combinations or compositions with the cellulose esters described herein.
  • the polyesters of this invention may have an inherent viscosity greater than 0.40 dL/g and a preferred inherent viscosity of between 0.40 and 1.60 dL/g as measured at a concentration of 0.5 weight% in tetrachlorethane / phenol [40:60].
  • the polyesters may be prepared according to polyester forming conditions known in the art.
  • the reaction should occur at a temperature to effect esterification and polycondensation.
  • a mixture of one or more aromatic or aliphatic dicarboxylic acids, preferably aliphatic dicarboxylic acids or ester forming derivatives thereof, and one or more diols may be heated in the presence of esterification and/or transesterification catalysts at temperatures in the range of about 150 C to 300 C, and more preferably in the range of about 200 C to 270 C.
  • the dicarboxylic acid is esterified with the diol(s) at temperatures of 200 C to 270 C and elevated pressure under nitrogen. Polycondensation is then effected by increasing the temperature and lowering the pressure while excess diol(s) is removed from the mixture.
  • the aliphatic polyesters of this invention may be prepared from diacids (or diesters) such as glutaric, adipic, succinic, and sebacic acids (or esters).
  • Aliphatic-aromatic copolyesters may be prepared from the diacids (or diesters) above and aromatic diesters such as dimethyl terephthalate, dimethyl isophthalate and dimethyl 2,6-naphthalene dicarboxylate.
  • aromatic diesters such as dimethyl terephthalate, dimethyl isophthalate and dimethyl 2,6-naphthalene dicarboxylate.
  • These diacids and diesters may be polymerized with several diols such as ethylene glycol, butanediol, diethylene glycol, hexanediol and polyethylene glycol.
  • polyesters suitable for this invention are: poly(ethylene glutarate), poly(tetramethylene glutarate), poly(tetramethylene adipate), poly(hexamethylene glutarate), poly(diethylene glutarate), poly(ethylene glutarate-co-terephthalate) [85/15], poly(ethylene glutarate-co-terephthalate) [70/30], poly(tetramethylene glutarate-co-
  • polyesters of this invention may be those prepared biologically, such as polyhydroxybutyrate or copolymers of polyhydroxybutyrate and polyhydroxyvalerate.
  • the polyesters may be prepared according to polyester forming conditions well known in the art.
  • the reaction should occur at a temperature to effect esterification and polycondensation.
  • a mixture of one or more dicarboxylic acids, preferably aromatic dicarboxylic acids, or ester forming derivatives thereof, and one or more diols may be heated in the presence of esterification and/or transesterification catalysts at temperatures in the range of about 150° to about 300°C, preferably, about 200°C to about 300°C, and even more preferably, about 260°C to about 300°C, and pressures of atmospheric to about 0.2 mm Hg.
  • the dicarboxylic acid is esterified with the diol(s) at elevated pressure and at a temperature at about 240°C to about 270°C. Polycondensation then is effected by increasing the temperature and lowering the pressure while excess diol is removed from the mixture.
  • degree of substitution refers to the number of substituents per anhydroglucose unit where the maximum DS/AGU is three.
  • degree of substitution will also be referred to as “DS” or DS/AGU" throughout the application. 12
  • the invention in one aspect, relates to a process for blending a cellulose ester with a functional additive, comprising:
  • the invention further relates to a process for blending a cellulose ester with a functional additive, comprising:
  • a functional additive comprising a plasticizer, another polymer, a
  • UV light stabilizer a dye, a pigment, an acid stabilizer, a flame retardant, an agricultural chemical, bioactive compound or a mixture thereof;
  • a cellulose ester comprising cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, 13
  • a first acid comprising acetic acid, propionic acid, butyric acid or a mixture thereof;
  • the invention relates to a method of producing a blend of a cellulose ester and a functional additive by coprecipitation from carboxylic acid(s) dopes, into water or aqueous carboxylic acid(s).
  • coprecipitation refers to the act of causing two or more chemicals or chemical compounds in an admixture solution or suspension in the presence of a solvent or solvent mixture to precipitate by the addition of a precipitant, such that the greater fraction of the desired chemicals or chemical compounds are inco ⁇ orated into the resulting precipitate phase.
  • a functional additive can be inco ⁇ orated into the precipitated cellulose ester blend.
  • the functional additive can be a plasticizer, another polymer, a UV light stabilizer such as organic phosphites known in the art, a dye or a pigment, an acid stabilizer, a flame retardant, an agricultural chemical (i.e. pesticide, herbicide, fertilizer, trace mineral), a bioactive compound (i.e. medicaments), or a mixture thereof.
  • the functional additive is a plasticizer, a UV stabilizer, a dye, or a mixture thereof. 14
  • plasticizers suitable for the present invention include, but are not limited to, dioctyl adipate, triethylene glycol-2-ethylhexanoate, polyethylene glutarate, dioctyl phthalate, diethyl phthalate, butyl benzyl phthalate, triethyl citrate, tripropinoin, polypropylene glycol dibenzoate, polyethylene succinate, sucrose acetate isobutyrate, triphenyl phosphate, polyalkyl glycoside, triethyl phosphate, diethyl phthalate, 2,2,4-trimethyl-l,3-pentane-diol diisobutyrate, a copolymer of phthalic acid, 1,3-butanediol, and 1,4-butanediol end capped by aliphatic epoxide, or a mixture thereof.
  • UV stabilizers and antioxidants suitable for the present invention include, but are not limited to, epoxides of a natural oil, and mineral oil, organic phosphites, or a mixture thereof.
  • organic dyes suitable for the present invention include, but are not limited to, C.I. Solvent Violet 13, C.I. Pigment Blue 15, C.I. Pigment Blue 28, C.I. Dispersion Violet 8, and C.I. Pigment Red 122.
  • a preferred dye is C.I. Solvent Violet 13.
  • the agricultural additive comprises an insecticide, a herbicide, a pesticide, a fertilizer, a trace mineral, or a mixture thereof.
  • the agricultural additive is an insecticide comprising an organochlorine compound, an organophosphate compound, an aryl compound, a heterocyclic compound, an organosulfur compound, a carbamate compound, a formamidine compound, a dinitrophenol compound, an organotin compound, a pyrethroid compound, an acylurea compound, a botanical compound, an antibiotic compound, a fumigant compound, a repellant compound, an inorganic compound, or a mixture thereof.
  • the organochlorine compound comprises a diphenyl aliphatic compound; hexachlorocyclohexane; a cyclodiene; or a polychlorote ⁇ ene.
  • the diphenyl aliphatic compound comprises l,l-dichloro-2,2- bis(p-chlorophenyl)ethane; l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane; dicofol; ethylan; chlorbenzilate; or methoxychlor.
  • the cyclodiene comprises chlordane; aldrin; dieldrin; heptachlor; endrin; mirex; endosulfan; or chlordecone.
  • the polychlorote ⁇ ene comprises toxaphene or strobane.
  • the organophosphate comprises an aliphatic phosphate compound; an aryl phosphate compound; or a heterocyclic phosphate compound.
  • Examples of aliphatic compounds include, but are not limited to, malathion; trichlorofon; monocrotophos; dimethoate; oxydemetonmethyl; dicrotophos; disulfoton; dichlorvos; mevinphos; methamidophos; or acephate.
  • Examples of phenyl compounds include, but are not limited to, ethyl parathion; methyl parathion; profenofos; sulprofos; isofenphos; fenitrothion; fenthion; or famphur.
  • heterocyclic compounds include, but are not limited to, diazinon; azinphos-methyl; chlo ⁇ yrifos; methidathion; phosmet; isazophos; chlo ⁇ yrifos-methyl; or azinphos-ethyl.
  • the organosulfur compound comprises tetradifon; propargite or ovex.
  • the carbamate comprises carbaryl; methomyl; carbofuran; aldicarb; oxamyl; thiodicarb; methiocarb; propoxur; bendiocarb; carbosulfan; aldoxycarb; trimethacarb; promecarb; or fenoxycarb.
  • the formamidine comprises chlordimeform; formetanate; or amitraz.
  • the dinitrophenol compound comprises binapacryl or dinocap.
  • the organotin compound comprises cyhexatin or fenbutatin-oxide.
  • the pyrethroid comprises allethrin; tetramethrin; bioresmethrin; bioallethrin; phonothrin; fenvalerate; permethrin; bifenthrin; lambda cyhalothrin; cypermethrin; cyfluthrin; delta methrin esfenvalerate; fenpropathrin; flucythrinate; fluvalinate; prallethrin; or tralomethrin.
  • the acylurea comprises triflumuron; chlorfluazuron; teflubenzuron; hexaflumuron; flufenoxuron; 16
  • the botanical compound comprises pyrethrum; nicotine; camphor; tu ⁇ entine; rotenone; limonene; or neem oil.
  • the antibiotic comprises avermectins.
  • the fumigant comprises methyl bromide; ethylene dichloride; sulfuryl fluoride; chlorothene; naphthalene; or paradichlorobenzene.
  • the repellant comprises dimethyl phthalate; dibutyl phthalate; benzyl benzoate; N-butyl acetanilide; dimethyl carbate; or diethyl toluamide.
  • the inorganic compound comprises sulfur; mercury; thallium; antimony; copper arsenate; inorganic fluorides; boric acid; disodium octaborate; or silica gels.
  • the agricultural additive is a herbicide comprising an ALSase inhibitor, an aromatic carboxylic acid, chloroacetamide, a triazine, an ESPSase inhibitor, an ACCase inhibitor, dinitroaniline compound, bentazon, a halohydroxybenzonitrile, a diphenyl ether, an isoxazolidone, paraquat or a mixture thereof.
  • the ALSase inhibitor comprises a sulfonylurea, a imidazolinone, or a triazolopyrimidine sulfonylanilide.
  • sulfonylureas include, but are not limited to, chlorsulfuron; chlorimuron-ethyl; nicosulfiiron; primisulfuron; thifensulfuron; metsulfuron; sulfometuron-mefhyl; or bensulfuron- methyl.
  • imidazolinones include, but are not limited to, imazaquin; imazethapyr; imazapyr; or imazamethabenz.
  • an example of a triazolopyrimidine sulfonylanilide includes, but is not limited to, flumetsulam.
  • the aromatic carboxylic acid comprises a phenoxyacetic acid, a benzoic acid, or an aryloxyphenoxypropionate.
  • phenoxyacetic acids include, but are not limited to, 2,4-dichlorophenoxyacetic acid (2,4-D); or 2,4,5- trichlorophenoxyacetic acid (2,4, 5-T).
  • benzoic acids include, but are not limited to, chloramben.
  • aryloxyphenoxypropionates include, but 17
  • the chloroacetamide comprises alachlor; metolachlor; propachlor; butachlor; diphenamide; napropamide; pronamide; propanil; or acetochlor.
  • the triazine comprises a chlorinated s-triazine; a methoxy s- triazine; a methylthio s-triazine; or an asymetrical triazine.
  • chlorinated s-triazines include, but are not limited to, atrazine; cyanazine; cyprozine; simazine; procyazine; or propazine.
  • methoxy s-triazines include, but are not limited to, atraton; prometon; secbumeton; or simeton.
  • methylthio s-triazines include, but are not limited to, ametryn; prometryn; terbutryn; simetryn; or desmetryn.
  • An example of an asymmetrical triazine includes, but is not limited to, Metribuzin.
  • An example of an ESPSase inhibitor includes, but is not limited to, glyphosphate.
  • the ACCase inhibitor comprises an aryloxyphenoxypropionate or a cyclohexenone.
  • aryloxyphenoxypropionates include, but are not limited to, diclofop- methyl; fluazifop-butyl; or quizalafop-ethyl.
  • cyclohexenones include, but are not limited to, sethoxydim; clethodim; alloxydim; or cycloxydim.
  • the dinitroaniline compound comprises a methylaniline herbicide or a sulfonylaniline.
  • methylaniline herbicides include, but are not limited to, trifluralin; pendimethalin; benefin; dinitramine; fluchloralin; or profluralin.
  • sulfonylaniline compounds include, but are not limited to, oryzalin or nitralin.
  • the halohydroxybenzonitrile comprises bromoxynil or ioxynil.
  • the isoxazolidone comprises clomazone.
  • the application of this invention provides the economic benefit of fewer processing steps in addition to fewer heat histories in the production of the cellulosic plastic materials. Moreover, the process of the present 18
  • invention permits the inclusion of a higher amount of a functional additive by providing more uniform distribution of the material in the cellulose ester.
  • Another advantage of the present invention with respect to agrochemicals involves the production of a granular material with timed and sustained release properties, lower handling toxicity by virtue of reduced dusting and encapsulation of the functional additive, and increased UV light stability or hydrolytic stability of sensitive materials.
  • the process of the present invention can also produce a cellulose ester blend, wherein the rate of release of the functional additive can be controlled.
  • the cellulose ester blend produced by the process of the present invention can be used to deliver drugs and other medicaments.
  • the process of the invention comprises adding a suitable functional additive, or additives package, to a solution of a first carboxylic acid and a cellulose ester.
  • the cellulose ester can be cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, cellulose propionate butyrate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate or a mixture thereof.
  • the cellulose ester is cellulose acetate, cellulose acetate propionate, or a mixture thereof.
  • the degree of substitution of the cellulose acetate is from 0.5 to 3.0, preferably 1.5 to 2.8, more preferably 1.8 to 2.2.
  • the cellulose acetate propionate has a degree of substitution of propionyl of from 0.1 to 3.0, preferably from 1.5 to 2.0.
  • the degree of substitution of acetyl is from 0.01 to 1.0, preferably 0.05 to 0.5. 19
  • the selection of the first acid can vary depending upon the end-use of the resulting cellulose ester blend.
  • the mixture of carboxylic acid and water is chosen to dissolve the cellulose ester and functional additives.
  • the first acid is a carboxylic acid.
  • the first acid is an aqueous carboxylic acid.
  • the first carboxylic acid is acetic acid, propionic acid, butyric acid, or a mixture thereof, optionally, containing an amount of water in sufficient quantities to dissolve the cellulose ester and functional additives.
  • the first acid is present in the amount of 60 to 90 % by weight and the water is from 2 to 15 % by weight of the admixture in step (a).
  • the first acid is present in the amount of 10 to 90 % by weight propionic acid or butyric acid to 30 % by weight water.
  • the functional additive is present in the amount of 1 to 50 % by weight, preferably 1 to 20 % by weight, of the cellulose ester of step (a).
  • the functional additive is added to a solution of the cellulose ester and first carboxylic acid followed by stirring the admixture to dissolve the functional additive to make a homogeneous solution.
  • preferred functional additives include plasticizers, UV stabilizers, and dyes.
  • the amount of the plasticizer(s) is from 1 to 40 % by weight of the cellulose ester in step (a), preferably from 15 to 25 % by weight of the plasticizer.
  • the functional additive is a plasticizer.
  • aqueous precipitating agent is defined as a solution comprising water and, optionally, one or more other components.
  • the aqueous precipitating agent is water.
  • the aqueous precipitating agent is a second acid and water.
  • the second acid is preferably soluble in water.
  • the second acid is a carboxylic acid, preferably acetic acid, propionic acid, butyric acid, or a mixture thereof.
  • the first and second acid can be the same or they can be different. The selection of the second acid can vary depending upon the cellulose ester that is used.
  • the precipitating agent can be any solvent miscible with carboxylic acid and having very limited solubility for cellulose esters and the functional additive.
  • the second acid is from 20 to 35 % by weight of the aqueous precipitating agent, preferably 10 to 30 % by weight.
  • the second acid is from 1 to 39 % by weight acetic acid, preferably, 0 to 15 % by weight acetic acid, and more preferably 10 to 15 % by weight acetic acid and from 39 to 1 % by weight propionic acid, preferably 15 to 0 % by weight propionic acid, more preferably from 15 to 10 % by weight propionic acid.
  • the amount of the aqueous precipitating agent is sufficient to dilute the concentration of the first acid in the admixture, which causes the cellulose ester / functional additive blend to coprecipitate.
  • the concentration of the first acid in step (a) is greater than the concentration of the second acid in the aqueous precipitating agent of step (b).
  • phase separation and precipitation take place.
  • the resulting precipitate is a carboxylic acid(s) / water wet cellulose ester solid phase which contains essentially all of the added functional additive and a dilute carboxylic acid(s) / water phase which contains only a small fraction of the functional additive.
  • the amount of the precipitating agent used will vary depending upon the type of cellulose ester and functional additive that are used as well as the temperature at which coprecipitation occurs. The temperature of the precipitating agent is from -10 to 25°C. Also, prior to step 21
  • step (b) the temperature of the admixture of step (a) is preferably adjusted to from -5 to
  • the first and/or second acid is the conjugate acid of the ester group of the cellulose ester. In one embodiment, the first and second acid are the same. In one embodiment, when cellulose acetate is used, the first and second acid is acetic acid. In one embodiment, the first and second acid are not the same. In another embodiment, the second acid comprises a mixture of two or more of acetic acid, propionic acid and butyric acid.
  • the admixture containing the cellulose ester, functional additive and the first acid is agitated in order to dissolve the functional additive.
  • the aqueous precipitating agent can be added to induce coprecipitation.
  • the temperature at which coprecipitation occurs can vary depending on which functional additives are used.
  • the precipitate is separated from the precipitation liquids.
  • the resulting precipitate can be washed with water in order to reduce acid content.
  • the precipitate can be further stabilized against thermal degradation or color development by the addition of a stabilizer by methods well known in the art.
  • useful stabilizing agents include, but are not limited to, potassium dihydrogen citrate, sodium citrate, calcium citrate, sodium lactate, calcium lactate, sodium oxylate, calcium acetate and sodium maleate. 22
  • the invention further relates to a process for preparing a cellulose ester/functional additive blend, comprising:
  • step (b) depositing the admixture of step (a) in a pelleter
  • step (d) immediately after step (c) or simultaneous with step (c), contacting the extruded admixture with a precipitating agent to precipitate the cellulose ester/functional additive to thereby produce an extrusion of the cellulose ester/functional additive blend;
  • the admixture comprising the cellulose ester, the functional additive and the first acid are added to a bath containing a precipitating agent in order to coprecipitate the cellulose ester/functional additive blend.
  • the admixture of step (a) can be added to a pelleter prior to contacting the admixture with the precipitating agent. Pelleters useful in the present invention are known in the art.
  • the admixture and pelleter are heated prior to adding the admixture of step (a) to the pelleter.
  • the admixture is heated from 5 to 60°C, preferably, 5 to 15°C, and the pelleter is heated from 5 to 60°C, preferably 5 to 15°C.
  • prior to step (c) the temperature of the pelleter is adjusted to -5 to 25°C.
  • the pelleter containing the admixture of step (a) is contacted with the precipitating agent.
  • the cutter end of the pelleter is submerged into a bath comprising the precipitating agent.
  • the precipitating agent is water.
  • the precipitating agent comprises a second acid.
  • the pellets can be washed with water, treated with a stabilizer, and dried to remove residual water as described above for the powder process.
  • the invention relates to a method for controlled release of an agricultural additive, preferably, comprising dispensing the controlled release matrix system, comprising:
  • components (a) and (b) form a controlled release matrix system, 24 in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive.
  • the invention further relates to a method for controlled release of a pharmaceutical additive in the proximity of a target for the additive, comprising dispensing the controlled release matrix system, comprising:
  • components (a) and (b) form a controlled release matrix system, preferably,
  • the procedure described above for preparing a cellulose ester/functional additive blend via coprecipitation can be used to produce a controlled release matrix system.
  • techniques known in the art can be used to prepare the controlled release matrix system.
  • the controlled release matrix system of the present invention can be prepared by microencapsulation, melt blending, film formation, or spray drying. Procedures for preparing the controlled release matrix system by these techniques are provided in the forthcoming examples.
  • the controlled release matrix system is a homogeneous mixture of the biodegradable cellulose ester and the agricultural or pharmaceutical additive.
  • the term "homogeneous mixture” is defined as an intimate mixture between the cellulose ester and the agricultural or pharmaceutical additive.
  • the cellulose ester and additive are mixed together. In one embodiment, the mixture is heated and the materials are melt-blended. The temperature at which the sample begins to melt is dependent on the physical properties (t.e. melting point, glass transition temperature) of the cellulose ester, the additive, or the combination of cellulose ester and the additive. Upon removal of the solvent, the cellulose ester forms a matrix, wherein the additive is dispersed throughout the matrix. The additive is not chemically bonded to the cellulose ester (t.e.
  • the additive is not loaded or inco ⁇ orated into the exterior surface pores of the matrix system. In these systems, the additive diffuses or leaches out of the pore once the pore undergoes hydrolytic or thermal degradation.
  • matrix systems are not a homogeneous mixture as defined above.
  • This system may comprise a residual solvent where the residual solvent comprises acetic acid, propionic acid, or a mixture thereof. The residual solvent may be present in this system in the amount of 0.005 to 0.5 % by weight of the matrix system.
  • the controlled release matrix system of the present invention permits the release of the agricultural or pharmaceutical additive at various rates depending upon the selection and the amount of the biodegradable cellulose ester and the agricultural or pharmaceutical additive.
  • Molecular weight and DS of the cellulose ester may affect the rate of release of the additive.
  • biodegradable is defined as degradation by at least one microorganism and/or its enzyme when the item (i.e. cellulose) is exposed to the microorganism under conditions which promote assimilation of the substrate by the microorganism.
  • Cellulose is degraded in the environment by both anaerobic and aerobic microorganisms.
  • Typical endproducts of this microbial degradation include cell biomass, methane (anaerobic only), carbon dioxide, water, and other fermentation products.
  • the ultimate endproducts depend upon the type of environment as well as the type of microbial population that is present.
  • cellulose esters were synthesized from 14 C-labelled acetate and subjected to a composting environment. The release of 14 CO produced by degradation of the material was monitored and was used as an indicator of the degradation of the ester linkages. As illustrated by the figure below, the degradation of cellulose acetate with DS 1.85, as evidenced by the production of 14 CO 2 , is rapid with the majority of the material degrading within a week.
  • Cellulose acetates with higher degrees of substitution require much longer periods of time to degrade. For example, cellulose acetate with DS 2.5 remains only partially degraded after 2 weeks time.
  • the additive is not chemically attached to the biodegradable cellulose ester.
  • the matrix system breaks apart and permits the release of the additive.
  • biodegradation of the cellulose ester occurs.
  • the hydrolysis of the chemical bond between the additive and the polymeric support material controls the release of the functional additive. The rate at which the cellulose ester biodegrades and the type of additive employed effect the rate at which the additive is released.
  • the selection of the biodegradable cellulose ester effects the release of the agricultural and pharmaceutical additive.
  • the biodegradable cellulose ester comprises cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, cellulose propionate butyrate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate, or a mixture thereof.
  • the biodegradable cellulose ester comprises cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or a mixture thereof.
  • the biodegradable cellulose ester has a degree of substitution of from 1.0 to 3.0. In another embodiment, the biodegradable cellulose ester is cellulose acetate with a degree of substitution of from 1.5 to 2.5, preferably from 1.8 to 2.2. In another embodiment, the biodegradable cellulose ester is cellulose acetate propionate with a degree of substitution of from 0.1 to 0.5 acetyl and from 1.6 to 2.0 propionyl. 30
  • biodegradable cellulose ester in the controlled release matrix system also effects the rate of release of the additive.
  • biodegradable cellulose ester is from 50 to 99.9 % by weight of the matrix system, preferably 70 to 99 % by weight of the matrix system.
  • the agricultural additive comprises an insecticide, a herbicide, a pesticide, a fertilizer, a trace mineral, or a mixture thereof.
  • the agricultural additive is an insecticide comprising an organochlorine compound, an organophosphate compound, an aryl compound, a heterocyclic compound, an organosulfur compound, a carbamate compound, a formamidine compound, a dinitrophenol compound, an organotin compound, a pyrethroid compound, an acylurea compound, a botanical compound, an antiobiotic, a fumigant compound, a repellant compound, an inorganic compound or a mixture thereof.
  • the organochlorine compound comprises a diphenyl aliphatic compound; hexachlorocyclohexane; a cyclodiene; or a polychlorote ⁇ ene.
  • the diphenyl aliphatic compound comprises l,l-dichloro-2,2- bis(p-chlorophenyl)ethane; l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane; dicofol; ethylan; chlorbenzilate; or methoxychlor.
  • the cyclodiene comprises chlordane; aldrin; dieldrin; heptachlor; endrin; mirex; endosulfan; or chlordecone.
  • the polychlorote ⁇ ene comprises toxaphene or strobane.
  • the organophosphate comprises an aliphatic compound; a phenyl compound; or a heterocyclic compound. Examples of aliphatic compounds include, but are not limited to, malathion; trichlorofon; monocrotophos; dimethoate; oxydemetonmethyl; dicrotophos; disulfoton; dichlorvos; mevinphos; methamidophos; or acephate.
  • phenyl compounds include, but are not limited to, ethyl parathion; methyl parathion; 31 profenofos; sulprofos; isofenphos; fenitrothion; fenthion; or famphur.
  • heterocyclic compounds include, but are not limited to, diazinon; azinphos-methyl; chlorpyrifos; methidathion; phosmet; isazophos; chlo ⁇ yrifos-methyl; or azinphos- ethyl.
  • the organosulfur compound comprises tetradifon; propargite or ovex.
  • the carbamate comprises carbaryl; methomyl; carbofuran; aldicarb; oxamyl; thiodicarb; methiocarb; propoxur; bendiocarb; carbosulfan; aldoxycarb; trimethacarb; promecarb; or fenoxycarb.
  • the formamidine comprises chlordimeform; formetanate; or amitraz.
  • the dinitrophenol compound comprises binapacryl or dinocap.
  • the organotin compound comprises cyhexatin or fenbutatin-oxide.
  • the pyrethroid comprises allethrin; tetramethrin; bioresmethrin; bioallethrin; phonothrin; fenvalerate; permethrin; bifenthrin; lambda cyhalothrin; cypermethrin; cyfluthrin; delta methrin esfenvalerate; fenpropathrin; flucythrinate; fluvalinate; prallethrin; or tralomethrin.
  • the acylurea comprises triflumuron; chlorfluazuron; teflubenzuron; hexaflumuron; flufenoxuron; flucycloxuron; or novaluron.
  • the botanical compound comprises pyrethrum; nicotine; camphor; tu ⁇ entine; rotenone; limonene; or neem oil.
  • the antibiotic comprises avermectins.
  • the fumigant comprises methyl bromide; ethylene dichloride; hydrogen cyanide; sulfuryl fluoride; chlorothene; ethylene oxide; naphthalene; or paradichlorobenzene.
  • the repellant comprises dimethyl phthalate; dibutyl phthalate; benzyl benzoate; N-butyl acetanilide; dimethyl carbate; or diethyl toluamide.
  • the inorganic compound comprises sulfur; mercury; thallium; antimony; copper arsenate; inorganic fluorides; boric acid; disodium octaborate; or silica gels.
  • the agricultural additive is a herbicide comprising an ALSase inhibitor, an aromatic carboxylic acid, chloroacetamide, a triazine, an ESPSase inhibitor, an ACCase inhibitor, dinitroaniline compound, bentazon, a 32 halohydroxybenzonitrile, a diphenyl ether, an isoxazolidone, paraquat or a mixture thereof.
  • the ALSase inhibitor comprises a sulfonylurea, a imidazolinone, or a triazolopyrimidine sulfonylanilide.
  • sulfonylureas include, but are not limited to, chlorsulfuron; chlorimuron-ethyl; nicosulfuron; primisulfuron; thifensulfuron; metsulfuron; sulfometuron-methyl; or bensulfuron- methyl.
  • imidazolinones include, but are not limited to, imazaquin; imazethapyr; imazapyr; or imazamethabenz.
  • an example of a triazolopyrimidine sulfonylanilide includes, but is not limited to, flumetsulam.
  • the aromatic carboxylic acid comprises a phenoxyacetic acid, a benzoic acid, or an aryloxyphenoxypropionate.
  • phenoxyacetic acids include, but are not limited to, 2,4-dichlorophenoxyacetic acid (2,4-D); or 2,4,5- trichlorophenoxyacetic acid (2,4, 5-T).
  • benzoic acids include, but are not limited to, dicamba or chloramben.
  • aryloxyphenoxypropionates include, but are not limited to, diclofop-methyl; fluazifop-butyl; or quizalafop- ethyl.
  • the chloroacetamide comprises alachlor; metolachlor; propachlor; butachlor; diphenamide; napropamide; pronamide; propanil; or acetochlor.
  • the triazine comprises a chlorinated s-triazine; a methoxy s-triazine; a methylthio s-triazine; or an asymmetrical triazine.
  • chlorinated s-triazines include, but are not limited to, atrazine; cyanazine; cyprozine; simazine; procyazine; or propazine.
  • methoxy s-triazines include, but are not limited to, atraton; prometon; secbumeton; or simeton.
  • methylthio s-triazines include, but are not limited to, ametryn; prometryn; terbutryn; simetryn; or desmetryn.
  • An example of an asymmetrical triazine includes, but is not limited to, Metribuzin.
  • An example of an ESPSase inhibitor includes, but is not limited to, glyphosphate.
  • the ACCase inhibitor comprises an aryloxyphenoxypropionate or a cyclohexenone.
  • aryloxyphenoxypropionates include, but are not limited to, diclofop-methyl; fluazifop-butyl; or quizalafop-ethyl.
  • 33 cyclohexenones include, but are not limited to, sethoxydim; clethodim; alloxydim; or cycloxydim.
  • the dinitroaniline compound comprises a methylaniline herbicide or a sulfonylaniline.
  • methylaniline herbicides include, but are not limited to, trifluralin; pendimethalin; benefin; dinitramine; fluchloralin; or profluralin.
  • sulfonylaniline compounds include, but are not limited to, oryzalin or nitralin.
  • the halohydroxybenzonitrile comprises bromoxynil or ioxynil.
  • the isoxazolidone comprises clomazone.
  • the amount of the agricultural additive that can be inco ⁇ orated into the matrix system can vary depending upon the agricultural additive and the rate of release of the additive.
  • the agricultural additive comprises from 0.1 to 50 % by weight, preferably from 0.1 to 30 % by weight, more preferably, from 0.1 to 20 % by weight of the matrix system.
  • the controlled release matrix system containing an agricultural additive can be disposed by techniques known in the art for the administration of agricultural, garden, or lawn chemicals.
  • the term "dispensing" is defined as a process of contacting or administering the controlled release matrix system of the present invention to a target.
  • the target can be a plant or soil.
  • the plant is an agricultural, garden or lawn plant.
  • a period of time sufficient to undergo biodegradation and release the additive refers to the time required to initiate release of the additive.
  • the time can vary for the release of the additive from the controlled release matrix system, depending upon the biodegradable cellulose ester and additive used. Once the initial release of the additive occurs, the duration of release of the additive can also vary depending upon the cellulose ester and additive employed.
  • the term “duration of release” is defined as the time required for substantially all of the 34 additive to escape the controlled release matrix system. The duration of release can be from days to years.
  • compositions can be inco ⁇ orated into the controlled release matrix system. Any pharmaceutical additive that is miscible with the biodegradable cellulose ester can be used in the present invention. Pharmaceutical additives useful in the present invention are disclosed in Physician's Desk Reference, which is herein inco ⁇ orated by reference.
  • the controlled release matrix system comprising the pharmaceutical additive can be in pharmaceutical compositions in the form of solid, semi-solid or liquid dosage forms, such as, for example, tablets, suppositories, pills, capsules, powders, liquids, suspensions, lotions, creams, gels, or the like, preferably in unit dosage form suitable for single administration of a precise dosage.
  • the controlled release matrix system may include other medicinal agents, pharmaceutical agents, carriers, adjuvants, diluents, etc.
  • fine powders or granules may contain diluting, dispersing, and/or surface active agents, and may be presented in water or in a syrup, in capsules or sachets in the dry state, or in a nonaqueous solution or suspension wherein suspending agents may be included, in tablets wherein binders and lubricants may be included, or in a suspension in water or a syrup. Where desirable or necessary, flavoring, preserving, suspending, thickening, or emulsifying agents may be included. Tablets and granules are preferred oral administration forms, and these may be coated.
  • Parenteral administration if used, is generally characterized by injection.
  • Injectables can be prepared in conventional forms, either as liquid solutions or 35 suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions.
  • the exact amount of the pharmaceutical additive will vary from subject to subject, depending on the species, age, weight and general condition of the subject, the severity of the disease, infection, or condition that is being treated or prevented, the particular pharmaceutical additive used, its mode of administration, and the like. Thus, it is not possible to specify an exact amount. However, an appropriate amount may be determined by one of ordinary skill in the art using only routine experimentation given the teachings herein.
  • the pharmaceutical additive is from 0.1 to .50 % by weight, preferably from 0.1 to 20 % by weight of the controlled release matrix system.
  • the controlled release matrix system containing the pharmaceutical additive can be administered to a subject.
  • the subject is a mammal, reptile, bird or fish.
  • the subject can be a human or another animal, wherein the animal can particularly be a domestic, food producing or wild animal.
  • domestic animals include, but are not limited to, dogs, cats, horses or birds.
  • food producing animals include, but are not limited to cows, pigs, chickens or sheep.
  • wild animals include, but are not limited to, lions, tigers, elephants, monkeys or bears.
  • the size and shape of the controlled release matrix system can vary depending upon the technique used to prepare the matrix system.
  • the matrix system can be a microcapsule or microsphere.
  • the microsphere is from 0.1 im to 500 im, preferably from 0.1 im to 100 im, and more preferably from 0.5 im to 5 im in diameter.
  • the matrix system can be a film, wherein the film has a thickness of from 3 mm to 250 mm or from 0.01 to 10 mils.
  • the matrix 36 system can be a fiber or a granule.
  • the matrix system can be a woven or spun fiber or a pelletized sphere or granule.
  • the invention further relates to a controlled release matrix system, comprising a homogeneous mixture of:
  • components (a) and (b) form a controlled release matrix system.
  • the invention further relates to a controlled release matrix system, consisting essentially of a homogeneous mixture of:
  • components (a) and (b) form a controlled release matrix system.
  • a small amount of residual plasticizer or surfactant may be inco ⁇ orated into the controlled release matrix system.
  • the cellulose ester material used in the examples was taken from normal production either as final product or as a solution, sampled just prior to precipitation.
  • the haze point is defined as the point where the acid dope of a cellulose ester begins to biphase.
  • the break point is the point where the cellulose ester solid phase appears.
  • the haze and break points are dependent on the type of cellulose ester, hydroxyl content, temperature, percent acid and percent water of the precipitation mixture.
  • PZ refers to plasticizer.
  • Dope is defined as cellulose ester dissolved in solvent.
  • DS/AGU or simply “DS” refers to the number of substituents per anhydroglucose units where the maximum DS/AGU is three.
  • AMU refers to atomic mass units.
  • the dope was added to the pellet maker and the remaining pellet maker parts were assembled.
  • the pelleter was placed with the cutter end submerged in the precipitation bath, air pressure and cutter drive were set and pellets were formed. The pellets were precipitated into water or dilute aqueous acetic acid.
  • the pellet precipitated materials were washed.
  • the pellets were stabilized by soaking the washed pellets in an 0.06 weight% aqueous potassium dihydrogen citrate solution and draining away the excess solution.
  • the washed pellets and stabilizer were dried in a forced air oven.
  • a solution of a cellulose ester is prepared by dissolving the desired cellulose ester in an appropriate water-immiscible organic solvent.
  • the organic solvent may be any one of a number of organic solvents, preferably one that dissolves the cellulose ester and the agricultural or pharmaceutical additive, has limited water solubility, and which forms a low-boiling point azeotrope with water.
  • To the solution of the cellulose ester is added the desired amount of the additive. The solution is stirred until the active material dissolves completely.
  • the percentage of the active material in the final product is calculated by dividing the weight of the active by the sum of the weights of the active material and the cellulose ester.
  • the percentage of additive in the cellulose ester may vary from 0.1 weight % to 50 weight %.
  • the maximum weight percent of active material inco ⁇ orated into the cellulose ester may be determined experimentally by increasing the weight percent of active material in the mixture until the active material begins to form a separate phase.
  • a known quantity of surfactant is weighed into a second beaker and water is added to make an aqueous solution of the surfactant.
  • the cellulose 41 is weighed into a second beaker and water is added to make an aqueous solution of the surfactant.
  • ester/additive/organic solvent mixture is added to the aqueous solution of surfactant prepared while stirring in a high shear mixer.
  • the solution is stirred to form an emulsion of the organic phase dispersed in the aqueous phase.
  • the mixer should have sufficient "shear" to form droplets that range in size from sub-micron to less than 500 microns. Samples may be removed and examined via microsopy to determine when the particle size has reached a desired level.
  • the emulsion is transferred to a vessel equipped with a heat source, stirrer, and a distillation apparatus.
  • the emulsion is heated to allow the organic solvent/water azeotrope to distill from solution.
  • phase separation of the distillate occurs, the aqueous layer is removed and returned it to the vessel.
  • the vessel temperature will begin to rise.
  • discontinue heating of the vessel and reconfigure the apparatus to continue the distillation under vacuum and apply heat to the flask to maintain the temperature of the contents of the vessel and continue distilling until the distillate is only water. Release the vacuum and discontinue heating the vessel. Allow the contents of the vessel (cellulose ester/additive- microspheres suspended in water) to cool to room temperature.
  • the cellulose ester/additive particles can be recovered by a number of techniques including centrifugation or filtration under vacuum.
  • the microspheres may be dried in a vacuum oven at a temperature that will remove the residual water from the particles but will not cause the particles to melt or decompose.
  • a cellulose ester, an additive and, optionally, a plasticizer were mixed in a jar.
  • the mixture was transferred to a melt blender.
  • the temperature of the melt blender is increased and the mixture is agitated until the sample becomes homogeneous.
  • the temperature at which the sample begins to melt is dependent on 42
  • melting point Tg
  • the blending is discontinued.
  • the sample is discharged from the mixer as soon as it begins to harden.
  • Film may be prepared by thermal extrusion using either a melt-blended or an admixture of the cellulose ester, additive, and optionally , a plasticizer, for example, on an extruder with a film die, or by simultaneous pressing and heating on a press plate.
  • a cellulose ester and an additive are dissolved or suspended in a suitable organic or aqueous solvent.
  • the solvent should be capable of dissolving or suspending both the cellulose ester and the biologically active material of interest.
  • the solution is then atomized and dried in the spray dryer using techniques known to those skilled in the art of spray drying.
  • the plasticizer content of all samples was measured by 'HNMR NMR was also used to determine DS propionyl.
  • the molecular weight (weight avg.-Mw) was determined by size exclusion chromatography. Results are reported as polystyrene equivalent molecular weight.
  • the plasticizer used for this example was 90 weight% - dioctyl adipate (DOA) and 10 weight% - triethylene glycol -2- ethylhexanoate.
  • DOA dioctyl adipate
  • the precipitated powders were washed 45 minutes with deionized water and dried in a forced air oven at 60 °C for 16 hours. The high number of 100+ % retention values was attributed to bias in dope solids determination.
  • Filterable solids in the liquids separated from the precipitated powders ranged from 0.001 to 0.008 weight percent and dissolved solids ranged from 0.030 to 0.097 weight percent.
  • the filtrate ranged from 20-22 weight% acetic acid and 10-1 1 weight% propionic acid by GC analysis. These powders were not stabilized, but when 15-20 g of the powders were placed individually into a 70 mm diameter mold and pressed at 175 psig at a temperature range of 160 to 170°C for 10 minutes, they molded into slightly yellow but clear disks.
  • PPT is defined as precipitate or precipitation herein.
  • Samples C 1 to 4 were precipitated at 60°C and 1000 ⁇ m agitator speed using deionized water containing 21 weight. % acetic acid, 11 weight. % propionic acid, in deionized water. Final filtrate acid concentrations were adjusted to approximately from 34 to 36 weight percent acid as acetic by addition of deionized water to the turbo after break point concentration was reached. Dilute acid addition time was from 6.5 to 7.5 minutes. Dissolved solids were separated from the filtrate acid by evaporation and sent for NMR analysis as Sample D. This analysis showed that only A2 polyester was present. Samples E 1 to 4 were precipitated using 13.4 weight% acetic acid and 6.6 weight% propionic acid in deionized water.
  • Retention data was obtained by producing two calibration curves of CAP482-20 mixed with varying concentrations of these plasticizers respectively.
  • the ratio of aromatic to backbone protons versus weight percent plasticizer produced linear calibration curves with r 2 (correlation coefficient) of 0.99266 for Plastolein 9765 and 0.99945 for Admex 523.
  • Final precipitation liquids acid concentrations were from 25 to 28 weight% (as acetic).
  • Example 6 Four Batches, Samples H 2 to 4 and Sample 1-1, of CAP482-20 were coprecipitated with dioctyl adipate plasticizer in a single blade mixer, by a procedure similar to procedure (A), for comparison testing of plastic properties.
  • the dope mixture was brought to the break point with 35 weight% mixed acetic / propionic acid (2:1 acid ratio) and then 10 weight% mixed acid was used to further reduce the acid concentration.
  • the resulting powder was water washed for 10 hours, centrifuged and vacuum dried These batches were pelleted.
  • Sample H-l is
  • PPT Temperature 43 °C 43 °C 43 °C 43 °C 43 °C Dope Solids: 11.90 wt % 11.85 wt % 11.90 wt % 11.04 wt % Agitator Speed: 300 RPM 125 RPM 100 RPM 120 RPM Washing Time: lOh lOh lOh lOh Drying Time: 12h 12h 12h 12h
  • H-l 1587 85 41.979 1.000 35.0 1.1 4.4 0.1 H-2 968 23 23.608 0.062 20.6 0.2 3.8 0.1 H-3 949 13 21.924 0.051 19.4 0.3 3.8 0.1 H-4 1066 18 25.780 0.106 22.5 0.2 3.9 0.1 1-1 1887 48 53.894 0.410 42.5 0.4 4.9 0.2
  • Table 9 contains data from batches that gave good plasticizer retention but poor thermal plasticization. They did not show indications of plasticization and molding when 20 grams of the coprecipitated powder were pressed on a 7 cm diameter mold at 175 psig and heated from 150 to 168 ° C in 10 minutes. The sample batches all produced clear precipitation liquids, indicating high retention of the additive with the cellulose ester, based on work with CAP482-20. The percent yield of dry powder indicated yields of from 89-98 %, based on the total weight of cellulose ester plus additive. Sample L-4 was analyzed by NMR spectroscopy for BBP retention, and was found to have a retention of 125 weight%. Sample L-4 also had the highest yield of 98 % indicating excellent retention.
  • Table 11 contains data from batches that gave good plasticized retention but poor thermal plasticization. They did not show indications of plasticization and molding when 20 grams of the coprecipitated powder were pressed on a 7 cm diameter mold at 175 psig and heated from 150 to 168 ° C in 10 minutes. The sample batches all produced hazy precipitation liquids, indicating possible low retention of the additive or dissolved ester solids, based on work with CAP482-20. Percent yield of dry powder was calculated, based on the total of ester solids plus additive weight. Only DOP and SAIB produced high yields, which indicated good additive retention. Example 7 batches demonstrate that water solubility of the 57
  • coprecipitated functional additive has a major effect on additive retention as shown by the zero retention of TEC.
  • Other indications of the importance of additive water solubility are given by the low percent yields for DEP, triethyl phosphate and Eastman 240 (see Table 10 for water solubilities).
  • Diethyl phthalate (DEP) and dimethyl phthalate (DMP) have been shown to have azeotropes with water and azeotropic losses in drying may be the reason for the low retention of the DEP and Eastman 240.
  • Another reason for the low retention in Eastman 240 may be attributed to the solubility properties of dimethyl phthalate.
  • the Hildebrand solubility parameters (a -(cal cm 3 ) 1/2 ) for DEP and DMP are 10.0 and 10.7 respectively, and both have a medium H-bond index.
  • the examples shown here seem to indicate that plasticizers or additives with Hildebrand solubility parameters less than 10.0 are better candidates for coprecipitation.
  • Dioctyl adipate (DOA) and dioctyl phthalate (DOP) both have high retentions in coprecipitation trials and their Hildebrand solubility parameters are 8.7 and 7.9 respectively. Both DOA and DOP have a medium H-bond index.
  • DOA and DOP have a medium H-bond index.
  • Triphenyl phosphate will coprecipitate with
  • Agitator Speed 1500 RPM 1500 RPM 1500 RPM 1500 RPM
  • Cellulose acetate CA398-30 was coprecipitated by procedure (A) containing BBP plasticizer and C.I. Solvent Violet 13 Dye.
  • the two cellulose acetate batches Rl and R3 were molded in a 7 cm round mold into hard smooth opaque disks.
  • the cellulose acetate propionate Batch SI was soft and sticky, even after washing and drying. Batch SI did mold very well at only 160 °C.
  • the disk was hazy but uniformly blue and very flexible and after two weeks of handling and room temperature storage had retained its weight.
  • This example demonstrates coprecipitation of a dye in cellulose acetate and again demonstrates retention of immiscible additives in a cellulose acetate matrix formed by coprecipitation. This example also demonstrates retention of high loading of additive.
  • the pu ⁇ ose of these trials was two fold: first, to demonstrate the ability to coprecipitate the cellulose acetate and functional additive product in pellet form, and secondly to demonstrate the ability to coprecipitate cellulose acetate with a more water soluble, more polar plasticizer which would produce a plasticized cellulose acetate product and demonstrate the ability to increase retention of the more water soluble additives in the cellulose ester.
  • Pellet precipitation was chosen, since pellets have less surface area per volume than powders, which would reduce the surface area of the particles, limiting the area available for diffusion of the additive out of the matrix.
  • Sample disks from Sample T-l and Sample V-l were molded in a 7 cm round mold at the conditions described in Example 7. Both Sample T-l and Sample V-l molded into clear hard but very yellow disks, Sample T-l being yellower than Sample V-l from the retained acetic acid and salts. These batches demonstrated that retention of the more water soluble additives could be increased and that pellets could be coprecipitated.
  • Dope Solids 23.60 wt% 19.4 wt% 22.02 wt% 22.02 wt%
  • Dope % Acetic Acid 61.20 wt% 56.5 wt% 62.0 wt% 62.0 wt%
  • Dope Temperature 32 °C 22 °C 22 °C 28 °C
  • Theoretical % DEP CA398-30 CA394-110 CA394-110 CA394-110
  • Example 10 General procedure for the formation of cellulose ester microspheres containing a biologically-active material.
  • a solution of the cellulose ester is prepared by dissolving the desired cellulose ester in an appropriate water-immiscible organic solvent.
  • the cellulose ester may be any one of a number of cellulose esters including cellulose acetates, cellulose acetate butyrates or cellulose acetate propionates of varying degrees of substitution of the ester and varying molecular weights.
  • the organic solvent may be any one of a number of organic solvents preferably one that dissolves the cellulose ester of choice, dissolves the biologically active material of choice, has limited water solubility and which forms a low-boiling azeotrope with water.
  • a known amount of the cellulose ester/organic solvent solution is weighed out.
  • the desired amount of the active material is added to the cellulose ester dissolved in the organic solvent.
  • the active material is stirred until it dissolves completely.
  • the percentage of the active material in the final product is calculated by dividing the weight of the active material by the sum of the weights of the active material and the cellulose ester.
  • the percentage of active material in the cellulose ester may vary from low (i.e. less than 1 weight per cent) levels to much higher levels (i.e. 50 weight per cent).
  • the maximum weight per cent of active material inco ⁇ orated into the cellulose ester may be determined experimentally by increasing the weight per cent of active material in the mixture until the active material begins to separate from the mixture.
  • a quantity of surfactant is weighed into a second beaker and water is added to make an aqueous solution of the surfactant.
  • the surfactant may be any number of commercially available water-soluble surfactants.
  • the surfactant should show the ability to stabilize droplets of the organic phase in the aqueous media without allowing the droplets to coalesce or phase separation to occur.
  • surfactant belongs to a class of materials known as alkyl polyglycosides.
  • the cellulose ester/active material/organic solvent is added to the aqueous solution of surfactant while stirring with a high shear mixer.
  • the solution is stirred during the entire addition to form an emulsion of the organic phase dispersed in the aqueous phase.
  • the mixer should have sufficient "shear" to form droplets that range in size from sub-micron to less than 100 microns.
  • the cellulose ester/active material particles can be recovered by a number of techniques including centrifugation or filtration under vacuum.
  • the microspheres may be dried in a vacuum oven at a temperature that will remove the residual water from the particles but will not cause the particles to melt or decompose.
  • a 10 % solution of CAP 482-0.5 in isopropyl acetate is prepared.
  • a known amount of the cellulose ester/organic solvent solution is weighed out.
  • 2,4-Dinitrophenol is added to the cellulose ester/isopropyl acetate solution in an amount ranging from 1 to 30 weight % of the active (based on the weight of CAP 482-0.5), in this case 10 % and the mixture is stirred until the dinitrophenol dissolves.
  • a surfactant is 67
  • the cellulose ester/active material/organic solvent is added to the aqueous solution of surfactant prepared while stirring with a high shear mixer.
  • the solution is stirred during the entire addition to form an emulsion of the organic phase dispersed in the aqueous phase.
  • the contents of the vessel are heated and the organic solvent/water azeotrope is allowed to distill from solution. Return water that separates from the azeotrope after distillation to the vessel. Continue distilling until the azeotrope is completely removed and the solvent remaining in the vessel is only water.
  • the cellulose ester/active material particles can be recovered by a number of techniques including centrifugation or filtration under vacuum.
  • Example 11 General example of the coprecipitation of a bioactive material into a cellulose ester matrix.
  • a synthetic dope was prepared by combining the cellulose ester, acetic and propionic acids and water in proportions that mimicked a commercially prepared dope. To this mixture was added a biologically active material. The mixture was heated and stirred until the active material dissolved. The product was precipitated by the addition of solutions of acetic acid and water to the mixture. The solutions were made progressively more dilute in acetic acid until only water was added.
  • a CAP 482-0.5 dope was prepared containing 13% CAP 482-0.5, 16 % water 42 % acetic acid and 29 % propionic acid. 2,4-Dinitrophenol was added at 20% (vs. CAP 482-0.5) and the mixture was stirred until the phenol dissolved. The product was then precipitated by the addition of successive solutions of 35 % acid (in a 2: 1 ratio of acetic to propionic acid), 10 % acid (in a 2:1 ration of acetic and propionic acid) and water. The product was isolated by filtration and washed with water until the filtrate was neutral. The sample was dried in vacuo to yield a product which resulted in 28 % recovery of 2,4-dinitrophenol.

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Abstract

The application relates to a process for blending a cellulose ester with a functional additive, by: (a) admixing the functional additive with the cellulose ester and a first acid; and (b) contacting the admixture with an aqueous precipitating agent, whereby a blend comprising the cellulose ester and the functional additive coprecipitates. The application further relates to a process for preparing a controlled release matrix system for an agricultural additive or a pharmaceutical additive, and to controlled release matrix system composed of a homogeneous mixture of (a) at least one biodegradable cellulose ester and (b) at least one agricultural additive or pharmaceutical additive.

Description

COPRECIPITATION OF CELLULOSE ESTERS WITH FUNCTIONAL ADDITIVES AND COMPOSITIONS THUS OBTAINABLE
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority upon United States provisional application serial no. 60/081,608 filed April 13, 1998, and the contents of which are hereby herein incoφorated by this reference in their entirety.
FIELD OF THE INVENTION
The invention relates to new methods for combining a cellulose ester with a functional additive to produce a plastic or a controlled release matrix system and method of using the system.
BACKGROUND
Cellulose esters precipitated as a dry powder or flake have been compounded with other materials by thermo-mechanical processes. Cellulose esters may also be mixed with other additives by dissolving the precipitated ester in a solvent, dispersing the additives in the resulting dope, and drying away or extracting the solvent.
One common method is to mix the cellulose ester with measured amounts of plasticizer, dye or pigment, and acid and/or UV light stabilizers in sigma blade mixers. The resulting admixture is then kneaded on a two roll mill with heat applied to compound the material into a homogeneous mixture, a compounded cellulosic plastic. A single screw extruder barrel with the appropriate feeder may take the place of the two roll mill.
Another option for compounding cellulosic plastics involves the use of a twin screw extruder. In the twin screw extruder, cellulose esters such as powders, flakes or pellets are fed into the extruder barrel along with the chemical additives. In the extruder, the materials progress through various stages, which provide the necessary mixing, kneading, and heat required to compound the cellulosic plastic. Materials other than monomeric plasticizers may be compounded with cellulose esters by use of twin screw extruders.
U.S. Patent No. 1,910,948 to Dreyfus teaches compounding a moldable cellulose derivative (cellulose acetate) with common cellulose acetate plasticizers, such as triacetin, alkyl sulfonamides and triphenyl phosphate, by use of a mixture of cellulose acetate powder with the plasticizer and a non-solvent for cellulose acetate, such as benzene, water and alcohol or mixtures of these. The purpose of the non-solvent is to aid in the dispersion of the cellulosic plasticizer. The non- solvent was dried away prior to molding of the plasticized powder. This compounding method provided a homogeneous moldable mixture without the application of heat in compounding.
U.S. Patent No. 4,282,209 to Tocker discloses a process for preparing an insecticide-polymer particle. The process involves combining a polymer, an insecticide, and an organic solvent to generate an admixture, and adding the admixture to a non-solvent in order to precipitate the insecticide-polymer particle. The preferred organic solvent is a halogenated aliphatic and the preferred non- solvent is a hydrocarbon. Numerous techniques have been described for preparing microcapsule shells surrounding a core have been reported. For example, British Patent 1,297,476 discloses a process for preparing a microcapsule containing a hydrophobic or hydrophilic core and polymeric shell material. The process involves admixing a cellulose ester, a core material and a glycol and adding the resultant mixture to water to produce droplets of the encapsulated core material.
US patent 3,796,669 reports on the use of a urea-formaldehyde polymer as an encapsulating agent with the polymer being formed in solution, encapsulating the target material. In US patents 5,225,278 and 5,277,979 Kielbania, Jr., et al. describe a technique for encapsulating materials by forming a polymer shell around a core phase by polymerizing a reactive compound containing at least two active methylene functional groups per molecule with a compound containing a methylene reactive crosslinking site.
Lo in US Patent 5,725,869 describes the preparation of microspheres from ethylcellulose by evaporation of an organic solvent from an emulsion of the polymer, an organic solvent and plasticzer from an aqueous solution containing an emulsifying agent. The spheres described by Lo were reported to be spongy and porous, unlike the previously reported hard polymer shells. These microspheres may include a material for later release when they are prepared or they may be prepared as "blank" spheres that can be used to absorb an active at a later time.
WO 99/00013 describes the incoφoration of agricultural actives into polymer matrices in the form of microparticles and subsequent controlled release into crops. The microparticles described are reported to be different than "microcapsules" in which a polymer shell surrounds a liquid or solid core that contains an active. The particles are said to be solid be solid throughout and that the active is distributed throughout the matrix material. The prior art also discloses controlled release particles, wherein the additive is released due to the hydrolytic or thermal degradation of the particle. European Patent Application No. 0 126 827 to Lewis et al. discloses a controlled release particle containing a biological additive to aquatic plants.
The prior art also discloses the incoφoration of an additive into the voids or pores of a cellulose ester. U.S. Patent No. 4, 106,926 to Thomas discloses a process for the preparation of a controlled release composition which involves contacting a porous cellulose ester carrier with a solution of a herbicide. U.S. Patent No.
4,997,599 to Domeshek et al. discloses the loading of an additive into the exterior surface pores cellulose acetate and derivatives thereof.
An example of solvent compounding is the acetone spinning of cellulose acetate fibers. The cellulose acetate is dissolved in acetone and dyes or pigments, or textile modifiers are added. The solution is then spun and the acetone solvent is either dried or extracted from the resulting fiber by an acetone and water co-solvent mixture.
Thus, there is still a need for an efficient method of preparing cellulose ester blends that contain functional additives. Moreover, there is a need for a controlled release matrix system that can release a functional additive, and, in particular, an agricultural or pharmaceutical additive.
SUMMARY OF THE INVENTION
In accordance with the puφose(s) of this invention, as embodied and broadly described herein, in one aspect, the invention relates to a process for blending a cellulose ester with a functional additive, comprising: (a) admixing the functional additive with the cellulose ester and a first acid; and
(b) contacting the admixture with an aqueous precipitating agent, whereby a blend comprising the cellulose ester and the functional additive coprecipitates.
In addition, this invention relates to a process for blending a cellulose ester with a functional additive, comprising:
(a) admixing
(i) a functional additive comprising a plasticizer, another polymer, a UV light stabilizer, a dye, a pigment, an acid stabilizer, a flame retardant, an agricultural chemical, bioactive compound or a mixture thereof;
(ii) a cellulose ester comprising cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate, or a mixture thereof; and
iii) a first acid comprising acetic acid, propionic acid, butyric acid or a mixture thereof; and
(b) contacting the admixture with an aqueous precipitating agent comprising water, acetic acid, propionic acid, butyric acid, or a mixture thereof, whereby a blend comprising the cellulose ester and the functional additive coprecipitates.
This invention also relates to a process for preparing a cellulose ester/functional additive blend, comprising:
(a) admixing the functional additive with the cellulose ester and a first acid;
(b) depositing the admixture of step (a) in a pelleter;
(c) extruding the admixture from the pelleter;
(d) immediately after step (c) or simultaneous with step (c), contacting the extruded admixture with a precipitating agent to precipitate the cellulose ester/functional additive to thereby produce an extrusion of the cellulose ester/functional additive blend; and
(e) cutting the precipitated extrusion into pellets.
This invention further relates to a process for preparing a controlled release matrix system, comprising:
(a) admixing an agricultural additive or a pharmaceutical additive with a biodegradable cellulose ester and a first acid; and
(b) contacting the admixture with an aqueous precipitating agent, whereby a blend comprising the cellulose ester and the agricultural or pharmaceutical additive coprecipitates, wherein the blend is a controlled release matrix system.
Additionally, this invention relates to a method for controlled release of an agricultural additive comprising dispensing the controlled release matrix system, further comprising:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive,
wherein components (a) and (b) form a controlled release matrix system,
in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive.
This invention also relates to a method for controlled release of a pharmaceutical additive in the proximity of a target for the additive, comprising dispensing the controlled release matrix system, comprising:
(a) at least one biodegradable cellulose ester; and
(b) at least one pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system,
in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive. 8
In addition, this invention further relates to a controlled release matrix system, comprising a homogeneous mixture of:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive or pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system.
This invention further relates to a controlled release matrix system, consisting essentially of a homogeneous mixture of:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive or pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system.
This invention provides for an efficient method of preparing cellulose ester blends that contain functional additives. It also provides a controlled release matrix system than can release a functional additive.
Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
DETAILED DESCRIPTION OF THE INVENTION
Before the present compositions of matter, products and methods are disclosed and described, it is to be understood that this invention is not limited to specific synthetic methods or to particular formulations, as such may, of course, vary. It is also to be understood that the terminology used herein is for the puφose of describing particular embodiments only and is not intended to be limiting.
As used in the specification and in the claims, "a" can mean one or more, depending upon the context in which it is used.
In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings:
The term "functional additive" as used herein refers to cellulosic plastic modifiers. These modifiers can include, but are not limited to, plasticizers, other polymers, UV light stabilizers, dyes and pigments, acid stabilizers, agricultural chemicals, and bioactive compounds.
After melt and/or solid phase polycondensation the polyesters have an inherent viscosity (IN.) of about 0.65 to about 1.2 dL/g, preferably 0.75 dL/g measured at 25°C in a 60/40 ratio by weight of phenol/tetrachloroethane.
"Other polymer" or "another polymer" is defined as a polymer which is not included as one of the other functional additives listed herein. The polymers of this 10
invention are preferably polyesters. The polyesters of this invention can be any polyester known in the art, but is preferably an aliphatic polyester, or an aromatic- aliphatic copolyester, and more preferably an aliphatic polyester. The polyesters of this invention may be miscible, partially miscible, or immiscible in certain combinations or compositions with the cellulose esters described herein. The polyesters of this invention may have an inherent viscosity greater than 0.40 dL/g and a preferred inherent viscosity of between 0.40 and 1.60 dL/g as measured at a concentration of 0.5 weight% in tetrachlorethane / phenol [40:60]. The polyesters may be prepared according to polyester forming conditions known in the art. The reaction should occur at a temperature to effect esterification and polycondensation. For example, a mixture of one or more aromatic or aliphatic dicarboxylic acids, preferably aliphatic dicarboxylic acids or ester forming derivatives thereof, and one or more diols may be heated in the presence of esterification and/or transesterification catalysts at temperatures in the range of about 150 C to 300 C, and more preferably in the range of about 200 C to 270 C. Normally, the dicarboxylic acid is esterified with the diol(s) at temperatures of 200 C to 270 C and elevated pressure under nitrogen. Polycondensation is then effected by increasing the temperature and lowering the pressure while excess diol(s) is removed from the mixture. The aliphatic polyesters of this invention may be prepared from diacids (or diesters) such as glutaric, adipic, succinic, and sebacic acids (or esters). Aliphatic-aromatic copolyesters may be prepared from the diacids (or diesters) above and aromatic diesters such as dimethyl terephthalate, dimethyl isophthalate and dimethyl 2,6-naphthalene dicarboxylate. These diacids and diesters may be polymerized with several diols such as ethylene glycol, butanediol, diethylene glycol, hexanediol and polyethylene glycol. Examples of polyesters suitable for this invention are: poly(ethylene glutarate), poly(tetramethylene glutarate), poly(tetramethylene adipate), poly(hexamethylene glutarate), poly(diethylene glutarate), poly(ethylene glutarate-co-terephthalate) [85/15], poly(ethylene glutarate-co-terephthalate) [70/30], poly(tetramethylene glutarate-co-
SUBSTΓΓUTE SHEET (RULE 26) 11
terephthalate) [85/15], poly(tetramethylene adipate-co-terephthalate) [85/15], poly(tetramethylene adipate-co-terephthalate) [70/30], poly(tetramethylene glutarate-co-terephthalate) [70/30], poly(tetramethylene-co-ethylene glutarate-co- terephthalate) [50/50;85/15], poly(tetramethylene-co-ethylene glutarate-co- terephthalate) [50/50; 70/30], poly(hexamethylene glutarate-co-terephthalate)
[75/25], poly(hexamethylene glutarate-co-terephthalate) [70/30], poly(ethylene-co- polyethylene glutarate) [91/9], poly(ethylene-co-polyethylene glutarate-co- terephthalate) [91/9;70/30]. The polyesters of this invention may be those prepared biologically, such as polyhydroxybutyrate or copolymers of polyhydroxybutyrate and polyhydroxyvalerate.
The polyesters may be prepared according to polyester forming conditions well known in the art. The reaction should occur at a temperature to effect esterification and polycondensation. For example, a mixture of one or more dicarboxylic acids, preferably aromatic dicarboxylic acids, or ester forming derivatives thereof, and one or more diols may be heated in the presence of esterification and/or transesterification catalysts at temperatures in the range of about 150° to about 300°C, preferably, about 200°C to about 300°C, and even more preferably, about 260°C to about 300°C, and pressures of atmospheric to about 0.2 mm Hg. Normally, the dicarboxylic acid is esterified with the diol(s) at elevated pressure and at a temperature at about 240°C to about 270°C. Polycondensation then is effected by increasing the temperature and lowering the pressure while excess diol is removed from the mixture.
The term "degree of substitution" as used herein refers to the number of substituents per anhydroglucose unit where the maximum DS/AGU is three. The term "degree of substitution" will also be referred to as "DS" or DS/AGU" throughout the application. 12
PREPARATION OF A CELLULOSE ESTER/FUNCTIONAL ADDITrVE BLEND BY COPRECΓPITATIQN
In accordance with the puφose(s) of this invention, as embodied and broadly described herein, the invention, in one aspect, relates to a process for blending a cellulose ester with a functional additive, comprising:
(a) admixing the functional additive with the cellulose ester and a first acid; and
(b) contacting the admixture with an aqueous precipitating agent, whereby a blend comprising the cellulose ester and the functional additive coprecipitates.
The invention further relates to a process for blending a cellulose ester with a functional additive, comprising:
(a) admixing
i) a functional additive comprising a plasticizer, another polymer, a
UV light stabilizer, a dye, a pigment, an acid stabilizer, a flame retardant, an agricultural chemical, bioactive compound or a mixture thereof;
ii) a cellulose ester comprising cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, 13
carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate, or a mixture thereof; and
iii) a first acid comprising acetic acid, propionic acid, butyric acid or a mixture thereof; and
(b) contacting the admixture with an aqueous precipitating agent comprising water, acetic acid, propionic acid, butyric acid, or a mixture thereof, whereby a blend comprising the cellulose ester and the functional additive coprecipitates.
The invention relates to a method of producing a blend of a cellulose ester and a functional additive by coprecipitation from carboxylic acid(s) dopes, into water or aqueous carboxylic acid(s). As used herein, the term "coprecipitation" refers to the act of causing two or more chemicals or chemical compounds in an admixture solution or suspension in the presence of a solvent or solvent mixture to precipitate by the addition of a precipitant, such that the greater fraction of the desired chemicals or chemical compounds are incoφorated into the resulting precipitate phase. In one embodiment, a functional additive can be incoφorated into the precipitated cellulose ester blend. In a particular embodiment, the functional additive can be a plasticizer, another polymer, a UV light stabilizer such as organic phosphites known in the art, a dye or a pigment, an acid stabilizer, a flame retardant, an agricultural chemical ( i.e. pesticide, herbicide, fertilizer, trace mineral), a bioactive compound (i.e. medicaments), or a mixture thereof. In a more preferred embodiment, the functional additive is a plasticizer, a UV stabilizer, a dye, or a mixture thereof. 14
Examples of plasticizers suitable for the present invention include, but are not limited to, dioctyl adipate, triethylene glycol-2-ethylhexanoate, polyethylene glutarate, dioctyl phthalate, diethyl phthalate, butyl benzyl phthalate, triethyl citrate, tripropinoin, polypropylene glycol dibenzoate, polyethylene succinate, sucrose acetate isobutyrate, triphenyl phosphate, polyalkyl glycoside, triethyl phosphate, diethyl phthalate, 2,2,4-trimethyl-l,3-pentane-diol diisobutyrate, a copolymer of phthalic acid, 1,3-butanediol, and 1,4-butanediol end capped by aliphatic epoxide, or a mixture thereof.
Examples of UV stabilizers and antioxidants suitable for the present invention include, but are not limited to, epoxides of a natural oil, and mineral oil, organic phosphites, or a mixture thereof.
Examples of organic dyes suitable for the present invention include, but are not limited to, C.I. Solvent Violet 13, C.I. Pigment Blue 15, C.I. Pigment Blue 28, C.I. Dispersion Violet 8, and C.I. Pigment Red 122. A preferred dye is C.I. Solvent Violet 13.
A wide variety of agricultural additives can be used in the present invention. In one embodiment, the agricultural additive comprises an insecticide, a herbicide, a pesticide, a fertilizer, a trace mineral, or a mixture thereof.
In another embodiment, the agricultural additive is an insecticide comprising an organochlorine compound, an organophosphate compound, an aryl compound, a heterocyclic compound, an organosulfur compound, a carbamate compound, a formamidine compound, a dinitrophenol compound, an organotin compound, a pyrethroid compound, an acylurea compound, a botanical compound, an antibiotic compound, a fumigant compound, a repellant compound, an inorganic compound, or a mixture thereof. 15
In another embodiment, the organochlorine compound comprises a diphenyl aliphatic compound; hexachlorocyclohexane; a cyclodiene; or a polychloroteφene. In one embodiment, the diphenyl aliphatic compound comprises l,l-dichloro-2,2- bis(p-chlorophenyl)ethane; l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane; dicofol; ethylan; chlorbenzilate; or methoxychlor. In another embodiment, the cyclodiene comprises chlordane; aldrin; dieldrin; heptachlor; endrin; mirex; endosulfan; or chlordecone. In another embodiment, the polychloroteφene comprises toxaphene or strobane. In another embodiment, the organophosphate comprises an aliphatic phosphate compound; an aryl phosphate compound; or a heterocyclic phosphate compound. Examples of aliphatic compounds include, but are not limited to, malathion; trichlorofon; monocrotophos; dimethoate; oxydemetonmethyl; dicrotophos; disulfoton; dichlorvos; mevinphos; methamidophos; or acephate. Examples of phenyl compounds include, but are not limited to, ethyl parathion; methyl parathion; profenofos; sulprofos; isofenphos; fenitrothion; fenthion; or famphur. Examples of heterocyclic compounds include, but are not limited to, diazinon; azinphos-methyl; chloφyrifos; methidathion; phosmet; isazophos; chloφyrifos-methyl; or azinphos-ethyl. In another embodiment, the organosulfur compound comprises tetradifon; propargite or ovex. In another embodiment, the carbamate comprises carbaryl; methomyl; carbofuran; aldicarb; oxamyl; thiodicarb; methiocarb; propoxur; bendiocarb; carbosulfan; aldoxycarb; trimethacarb; promecarb; or fenoxycarb. In another embodiment, the formamidine comprises chlordimeform; formetanate; or amitraz. In another embodiment, the dinitrophenol compound comprises binapacryl or dinocap. In another embodiment, the organotin compound comprises cyhexatin or fenbutatin-oxide. In another embodiment, the pyrethroid comprises allethrin; tetramethrin; bioresmethrin; bioallethrin; phonothrin; fenvalerate; permethrin; bifenthrin; lambda cyhalothrin; cypermethrin; cyfluthrin; delta methrin esfenvalerate; fenpropathrin; flucythrinate; fluvalinate; prallethrin; or tralomethrin. In another embodiment, the acylurea comprises triflumuron; chlorfluazuron; teflubenzuron; hexaflumuron; flufenoxuron; 16
flucycloxuron; or novaluron. In another embodiment, the botanical compound comprises pyrethrum; nicotine; camphor; tuφentine; rotenone; limonene; or neem oil. In another embodiment, the antibiotic comprises avermectins. In another embodiment, the fumigant comprises methyl bromide; ethylene dichloride; sulfuryl fluoride; chlorothene; naphthalene; or paradichlorobenzene. In another embodiment, the repellant comprises dimethyl phthalate; dibutyl phthalate; benzyl benzoate; N-butyl acetanilide; dimethyl carbate; or diethyl toluamide. In another embodiment, the inorganic compound comprises sulfur; mercury; thallium; antimony; copper arsenate; inorganic fluorides; boric acid; disodium octaborate; or silica gels.
In another embodiment, the agricultural additive is a herbicide comprising an ALSase inhibitor, an aromatic carboxylic acid, chloroacetamide, a triazine, an ESPSase inhibitor, an ACCase inhibitor, dinitroaniline compound, bentazon, a halohydroxybenzonitrile, a diphenyl ether, an isoxazolidone, paraquat or a mixture thereof.
In another embodiment, the ALSase inhibitor comprises a sulfonylurea, a imidazolinone, or a triazolopyrimidine sulfonylanilide. Examples of sulfonylureas include, but are not limited to, chlorsulfuron; chlorimuron-ethyl; nicosulfiiron; primisulfuron; thifensulfuron; metsulfuron; sulfometuron-mefhyl; or bensulfuron- methyl. Examples of imidazolinones include, but are not limited to, imazaquin; imazethapyr; imazapyr; or imazamethabenz. An example of a triazolopyrimidine sulfonylanilide includes, but is not limited to, flumetsulam. In another embodiment, the aromatic carboxylic acid comprises a phenoxyacetic acid, a benzoic acid, or an aryloxyphenoxypropionate. Examples of phenoxyacetic acids include, but are not limited to, 2,4-dichlorophenoxyacetic acid (2,4-D); or 2,4,5- trichlorophenoxyacetic acid (2,4, 5-T). Examples of benzoic acids include, but are not limited to, chloramben. Examples of aryloxyphenoxypropionates include, but 17
are not limited to, diclofop-methyl; fluazifop-butyl; or quizalafop-ethyl. In another embodiment, the chloroacetamide comprises alachlor; metolachlor; propachlor; butachlor; diphenamide; napropamide; pronamide; propanil; or acetochlor. In another embodiment, the triazine comprises a chlorinated s-triazine; a methoxy s- triazine; a methylthio s-triazine; or an asymetrical triazine. Examples of chlorinated s-triazines include, but are not limited to, atrazine; cyanazine; cyprozine; simazine; procyazine; or propazine. Examples of methoxy s-triazines include, but are not limited to, atraton; prometon; secbumeton; or simeton. Examples of methylthio s-triazines include, but are not limited to, ametryn; prometryn; terbutryn; simetryn; or desmetryn. An example of an asymmetrical triazine includes, but is not limited to, Metribuzin. An example of an ESPSase inhibitor includes, but is not limited to, glyphosphate. In another embodiment, the ACCase inhibitor comprises an aryloxyphenoxypropionate or a cyclohexenone. Examples of aryloxyphenoxypropionates include, but are not limited to, diclofop- methyl; fluazifop-butyl; or quizalafop-ethyl. Examples of cyclohexenones include, but are not limited to, sethoxydim; clethodim; alloxydim; or cycloxydim. In another embodiment, the dinitroaniline compound comprises a methylaniline herbicide or a sulfonylaniline. Examples of methylaniline herbicides include, but are not limited to, trifluralin; pendimethalin; benefin; dinitramine; fluchloralin; or profluralin. Examples of sulfonylaniline compounds include, but are not limited to, oryzalin or nitralin. In another embodiment, the halohydroxybenzonitrile comprises bromoxynil or ioxynil. In another embodiment, the isoxazolidone comprises clomazone.
The advantages of the present invention vary with the particular application.
In cellulosic plastics manufacturing, the application of this invention provides the economic benefit of fewer processing steps in addition to fewer heat histories in the production of the cellulosic plastic materials. Moreover, the process of the present 18
invention permits the inclusion of a higher amount of a functional additive by providing more uniform distribution of the material in the cellulose ester.
Another advantage of the present invention with respect to agrochemicals involves the production of a granular material with timed and sustained release properties, lower handling toxicity by virtue of reduced dusting and encapsulation of the functional additive, and increased UV light stability or hydrolytic stability of sensitive materials.
The process of the present invention can also produce a cellulose ester blend, wherein the rate of release of the functional additive can be controlled. The cellulose ester blend produced by the process of the present invention can be used to deliver drugs and other medicaments.
The process of the invention comprises adding a suitable functional additive, or additives package, to a solution of a first carboxylic acid and a cellulose ester. In one embodiment, the cellulose ester can be cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, cellulose propionate butyrate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate or a mixture thereof. In a preferred embodiment, the cellulose ester is cellulose acetate, cellulose acetate propionate, or a mixture thereof. In one embodiment, the degree of substitution of the cellulose acetate is from 0.5 to 3.0, preferably 1.5 to 2.8, more preferably 1.8 to 2.2. In another embodiment, the cellulose acetate propionate has a degree of substitution of propionyl of from 0.1 to 3.0, preferably from 1.5 to 2.0. The degree of substitution of acetyl is from 0.01 to 1.0, preferably 0.05 to 0.5. 19
The selection of the first acid can vary depending upon the end-use of the resulting cellulose ester blend. The mixture of carboxylic acid and water is chosen to dissolve the cellulose ester and functional additives. In one embodiment, the first acid is a carboxylic acid. In another embodiment, the first acid is an aqueous carboxylic acid. In a preferred embodiment, the first carboxylic acid is acetic acid, propionic acid, butyric acid, or a mixture thereof, optionally, containing an amount of water in sufficient quantities to dissolve the cellulose ester and functional additives. Preferably, the first acid is present in the amount of 60 to 90 % by weight and the water is from 2 to 15 % by weight of the admixture in step (a).
More preferably, the first acid is present in the amount of 10 to 90 % by weight propionic acid or butyric acid to 30 % by weight water.
The functional additive is present in the amount of 1 to 50 % by weight, preferably 1 to 20 % by weight, of the cellulose ester of step (a).
In one embodiment, the functional additive is added to a solution of the cellulose ester and first carboxylic acid followed by stirring the admixture to dissolve the functional additive to make a homogeneous solution. As described above, preferred functional additives include plasticizers, UV stabilizers, and dyes. In one embodiment, the amount of the plasticizer(s) is from 1 to 40 % by weight of the cellulose ester in step (a), preferably from 15 to 25 % by weight of the plasticizer. In a preferred embodiment, the functional additive is a plasticizer.
Once the cellulose ester and functional additive have been dissolved, the admixture is contacted with an aqueous precipitating agent in order to coprecipitate the cellulose ester/functional additive blend. The term "aqueous precipitating agent" is defined as a solution comprising water and, optionally, one or more other components. In one embodiment, the aqueous precipitating agent is water. In 20 another embodiment, the aqueous precipitating agent is a second acid and water. The second acid is preferably soluble in water. In one embodiment, the second acid is a carboxylic acid, preferably acetic acid, propionic acid, butyric acid, or a mixture thereof. In the present invention, the first and second acid can be the same or they can be different. The selection of the second acid can vary depending upon the cellulose ester that is used. The precipitating agent can be any solvent miscible with carboxylic acid and having very limited solubility for cellulose esters and the functional additive.
In one embodiment, the second acid is from 20 to 35 % by weight of the aqueous precipitating agent, preferably 10 to 30 % by weight. In a preferred embodiment, the second acid is from 1 to 39 % by weight acetic acid, preferably, 0 to 15 % by weight acetic acid, and more preferably 10 to 15 % by weight acetic acid and from 39 to 1 % by weight propionic acid, preferably 15 to 0 % by weight propionic acid, more preferably from 15 to 10 % by weight propionic acid.
The amount of the aqueous precipitating agent is sufficient to dilute the concentration of the first acid in the admixture, which causes the cellulose ester / functional additive blend to coprecipitate. In one embodiment, prior to the contacting step (b), the concentration of the first acid in step (a) is greater than the concentration of the second acid in the aqueous precipitating agent of step (b). As the admixture becomes increasingly less concentrated in first acid, phase separation and precipitation take place. The resulting precipitate is a carboxylic acid(s) / water wet cellulose ester solid phase which contains essentially all of the added functional additive and a dilute carboxylic acid(s) / water phase which contains only a small fraction of the functional additive. The amount of the precipitating agent used will vary depending upon the type of cellulose ester and functional additive that are used as well as the temperature at which coprecipitation occurs. The temperature of the precipitating agent is from -10 to 25°C. Also, prior to step 21
(b), the temperature of the admixture of step (a) is preferably adjusted to from -5 to
-25°C.
In another embodiment, the first and/or second acid is the conjugate acid of the ester group of the cellulose ester. In one embodiment, the first and second acid are the same. In one embodiment, when cellulose acetate is used, the first and second acid is acetic acid. In one embodiment, the first and second acid are not the same. In another embodiment, the second acid comprises a mixture of two or more of acetic acid, propionic acid and butyric acid.
In another embodiment, prior to coprecipitation, the admixture containing the cellulose ester, functional additive and the first acid is agitated in order to dissolve the functional additive. Once the functional additive has been dissolved, the aqueous precipitating agent can be added to induce coprecipitation.
The temperature at which coprecipitation occurs can vary depending on which functional additives are used.
Once precipitation is complete, the precipitate is separated from the precipitation liquids. The resulting precipitate can be washed with water in order to reduce acid content.
The precipitate can be further stabilized against thermal degradation or color development by the addition of a stabilizer by methods well known in the art. Examples of useful stabilizing agents include, but are not limited to, potassium dihydrogen citrate, sodium citrate, calcium citrate, sodium lactate, calcium lactate, sodium oxylate, calcium acetate and sodium maleate. 22
Once the precipitate has been stabilized, residual water can be removed from the precipitate by centrifugation. The cellulose ester/functional additive blend is then dried by conventional techniques.
The invention further relates to a process for preparing a cellulose ester/functional additive blend, comprising:
(a) admixing the functional additive with the cellulose ester and a first acid;
(b) depositing the admixture of step (a) in a pelleter;
(c) extruding the admixture from the pelleter;
(d) immediately after step (c) or simultaneous with step (c), contacting the extruded admixture with a precipitating agent to precipitate the cellulose ester/functional additive to thereby produce an extrusion of the cellulose ester/functional additive blend; and
(e) cutting the precipitated extrusion into pellets.
As described above, the admixture comprising the cellulose ester, the functional additive and the first acid are added to a bath containing a precipitating agent in order to coprecipitate the cellulose ester/functional additive blend. In another embodiment of the invention, the admixture of step (a) can be added to a pelleter prior to contacting the admixture with the precipitating agent. Pelleters useful in the present invention are known in the art. In another embodiment, prior to adding the admixture of step (a) to the pelleter, the admixture and pelleter are heated. In one embodiment, the admixture is heated from 5 to 60°C, preferably, 5 to 15°C, and the pelleter is heated from 5 to 60°C, preferably 5 to 15°C. In one 23 embodiment, prior to step (c) the temperature of the pelleter is adjusted to -5 to 25°C.
In one embodiment, the pelleter containing the admixture of step (a) is contacted with the precipitating agent. In another embodiment, the cutter end of the pelleter is submerged into a bath comprising the precipitating agent. In one embodiment, the precipitating agent is water. In another embodiment, the precipitating agent comprises a second acid. Once the pelleter extrudes the admixture of step (a) into the bath containing the precipitating agent, a pellet comprising the cellulose ester/ functional additive is produced. In one embodiment, the precipitating agent is heated from 0 to 23 °C prior to the contacting step.
Once the pellet of the cellulose ester/functional additive blend is produced, the pellets can be washed with water, treated with a stabilizer, and dried to remove residual water as described above for the powder process.
PREPARATION OF A CONTROLLED RELEASE MATRIX SYSTEM
In accordance with the puφoses of this invention, as embodied and broadly described herein, the invention relates to a method for controlled release of an agricultural additive, preferably, comprising dispensing the controlled release matrix system, comprising:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive,
wherein components (a) and (b) form a controlled release matrix system, 24 in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive.
The invention further relates to a method for controlled release of a pharmaceutical additive in the proximity of a target for the additive, comprising dispensing the controlled release matrix system, comprising:
(a) at least one biodegradable cellulose ester; and
(b) at least one pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system, preferably,
in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive.
In one embodiment, the procedure described above for preparing a cellulose ester/functional additive blend via coprecipitation can be used to produce a controlled release matrix system. In another embodiment, techniques known in the art can be used to prepare the controlled release matrix system. The controlled release matrix system of the present invention can be prepared by microencapsulation, melt blending, film formation, or spray drying. Procedures for preparing the controlled release matrix system by these techniques are provided in the forthcoming examples.
The controlled release matrix system is a homogeneous mixture of the biodegradable cellulose ester and the agricultural or pharmaceutical additive. The term "homogeneous mixture" is defined as an intimate mixture between the cellulose ester and the agricultural or pharmaceutical additive. In the present 25 invention, the cellulose ester and additive are mixed together. In one embodiment, the mixture is heated and the materials are melt-blended. The temperature at which the sample begins to melt is dependent on the physical properties (t.e. melting point, glass transition temperature) of the cellulose ester, the additive, or the combination of cellulose ester and the additive. Upon removal of the solvent, the cellulose ester forms a matrix, wherein the additive is dispersed throughout the matrix. The additive is not chemically bonded to the cellulose ester (t.e. by covalent or ionic bonds), which is a feature of prior art controlled release particles. Moreover, the additive is not loaded or incoφorated into the exterior surface pores of the matrix system. In these systems, the additive diffuses or leaches out of the pore once the pore undergoes hydrolytic or thermal degradation. These matrix systems are not a homogeneous mixture as defined above. This system may comprise a residual solvent where the residual solvent comprises acetic acid, propionic acid, or a mixture thereof. The residual solvent may be present in this system in the amount of 0.005 to 0.5 % by weight of the matrix system.
The controlled release matrix system of the present invention permits the release of the agricultural or pharmaceutical additive at various rates depending upon the selection and the amount of the biodegradable cellulose ester and the agricultural or pharmaceutical additive. Molecular weight and DS of the cellulose ester may affect the rate of release of the additive. As used herein, the term "biodegradable" is defined as degradation by at least one microorganism and/or its enzyme when the item (i.e. cellulose) is exposed to the microorganism under conditions which promote assimilation of the substrate by the microorganism. Cellulose is degraded in the environment by both anaerobic and aerobic microorganisms. Typical endproducts of this microbial degradation include cell biomass, methane (anaerobic only), carbon dioxide, water, and other fermentation products. The ultimate endproducts depend upon the type of environment as well as the type of microbial population that is present. U.S. Patent Nos. 5,594,068; 26
5,580,911; and 5,559,171 are incoφorated herein by reference for a detailed discussion on biodegradability. Biodegradability can also occur by use of fungi.
Biodegradation of cellulose esters in a composting environment has been demonstrated. The factors that effect the rate of degradation are the type of substituent (i.e. acetate, propionate or butyrate) and the degree of substitution of the cellulose. Typically, lower DS material degrades faster than high DS material and smaller substituents (acetate) degrade faster than larger ones.
A number of cellulose esters were synthesized from 14C-labelled acetate and subjected to a composting environment. The release of 14CO produced by degradation of the material was monitored and was used as an indicator of the degradation of the ester linkages. As illustrated by the figure below, the degradation of cellulose acetate with DS 1.85, as evidenced by the production of 14CO2, is rapid with the majority of the material degrading within a week.
Cellulose acetates with higher degrees of substitution require much longer periods of time to degrade. For example, cellulose acetate with DS 2.5 remains only partially degraded after 2 weeks time.
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29 could administer the system at a time when biodegradation is not occuring (i.e. cold winter months) and release would begin during the spring when the soil temperature warms and microbial activity begins.
As described above, the additive is not chemically attached to the biodegradable cellulose ester. Thus, upon biodegradation of the controlled release matrix system, the matrix system breaks apart and permits the release of the additive. In the present invention, biodegradation of the cellulose ester occurs. In some prior art controlled release systems the hydrolysis of the chemical bond between the additive and the polymeric support material controls the release of the functional additive. The rate at which the cellulose ester biodegrades and the type of additive employed effect the rate at which the additive is released.
As described above, the selection of the biodegradable cellulose ester effects the release of the agricultural and pharmaceutical additive. In one embodiment, the biodegradable cellulose ester comprises cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, cellulose propionate butyrate, carboxymethylcellulose acetate, carboxymethylcellulose acetate propionate, carboxymethylcellulose acetate butyrate, cellulose acetate butyrate succinate, or a mixture thereof. In a preferred embodiment, the biodegradable cellulose ester comprises cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or a mixture thereof.
In one embodiment, the biodegradable cellulose ester has a degree of substitution of from 1.0 to 3.0. In another embodiment, the biodegradable cellulose ester is cellulose acetate with a degree of substitution of from 1.5 to 2.5, preferably from 1.8 to 2.2. In another embodiment, the biodegradable cellulose ester is cellulose acetate propionate with a degree of substitution of from 0.1 to 0.5 acetyl and from 1.6 to 2.0 propionyl. 30
The amount of the biodegradable cellulose ester in the controlled release matrix system also effects the rate of release of the additive. In one embodiment, biodegradable cellulose ester is from 50 to 99.9 % by weight of the matrix system, preferably 70 to 99 % by weight of the matrix system.
A wide variety of agricultural additives can be used in the present invention. In one embodiment, the agricultural additive comprises an insecticide, a herbicide, a pesticide, a fertilizer, a trace mineral, or a mixture thereof.
In another embodiment, the agricultural additive is an insecticide comprising an organochlorine compound, an organophosphate compound, an aryl compound, a heterocyclic compound, an organosulfur compound, a carbamate compound, a formamidine compound, a dinitrophenol compound, an organotin compound, a pyrethroid compound, an acylurea compound, a botanical compound, an antiobiotic, a fumigant compound, a repellant compound, an inorganic compound or a mixture thereof.
In another embodiment, the organochlorine compound comprises a diphenyl aliphatic compound; hexachlorocyclohexane; a cyclodiene; or a polychloroteφene. In one embodiment, the diphenyl aliphatic compound comprises l,l-dichloro-2,2- bis(p-chlorophenyl)ethane; l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane; dicofol; ethylan; chlorbenzilate; or methoxychlor. In another embodiment, the cyclodiene comprises chlordane; aldrin; dieldrin; heptachlor; endrin; mirex; endosulfan; or chlordecone. In another embodiment, the polychloroteφene comprises toxaphene or strobane. In another embodiment, the organophosphate comprises an aliphatic compound; a phenyl compound; or a heterocyclic compound. Examples of aliphatic compounds include, but are not limited to, malathion; trichlorofon; monocrotophos; dimethoate; oxydemetonmethyl; dicrotophos; disulfoton; dichlorvos; mevinphos; methamidophos; or acephate. Examples of phenyl compounds include, but are not limited to, ethyl parathion; methyl parathion; 31 profenofos; sulprofos; isofenphos; fenitrothion; fenthion; or famphur. Examples of heterocyclic compounds include, but are not limited to, diazinon; azinphos-methyl; chlorpyrifos; methidathion; phosmet; isazophos; chloφyrifos-methyl; or azinphos- ethyl. In another embodiment, the organosulfur compound comprises tetradifon; propargite or ovex. In another embodiment, the carbamate comprises carbaryl; methomyl; carbofuran; aldicarb; oxamyl; thiodicarb; methiocarb; propoxur; bendiocarb; carbosulfan; aldoxycarb; trimethacarb; promecarb; or fenoxycarb. In another embodiment, the formamidine comprises chlordimeform; formetanate; or amitraz. In another embodiment, the dinitrophenol compound comprises binapacryl or dinocap. In another embodiment, the organotin compound comprises cyhexatin or fenbutatin-oxide. In another embodiment, the pyrethroid comprises allethrin; tetramethrin; bioresmethrin; bioallethrin; phonothrin; fenvalerate; permethrin; bifenthrin; lambda cyhalothrin; cypermethrin; cyfluthrin; delta methrin esfenvalerate; fenpropathrin; flucythrinate; fluvalinate; prallethrin; or tralomethrin. In another embodiment, the acylurea comprises triflumuron; chlorfluazuron; teflubenzuron; hexaflumuron; flufenoxuron; flucycloxuron; or novaluron. In another embodiment, the botanical compound comprises pyrethrum; nicotine; camphor; tuφentine; rotenone; limonene; or neem oil. In another embodiment, the antibiotic comprises avermectins. In another embodiment, the fumigant comprises methyl bromide; ethylene dichloride; hydrogen cyanide; sulfuryl fluoride; chlorothene; ethylene oxide; naphthalene; or paradichlorobenzene. In another embodiment, the repellant comprises dimethyl phthalate; dibutyl phthalate; benzyl benzoate; N-butyl acetanilide; dimethyl carbate; or diethyl toluamide. In another embodiment, the inorganic compound comprises sulfur; mercury; thallium; antimony; copper arsenate; inorganic fluorides; boric acid; disodium octaborate; or silica gels.
In another embodiment, the agricultural additive is a herbicide comprising an ALSase inhibitor, an aromatic carboxylic acid, chloroacetamide, a triazine, an ESPSase inhibitor, an ACCase inhibitor, dinitroaniline compound, bentazon, a 32 halohydroxybenzonitrile, a diphenyl ether, an isoxazolidone, paraquat or a mixture thereof.
In another embodiment, the ALSase inhibitor comprises a sulfonylurea, a imidazolinone, or a triazolopyrimidine sulfonylanilide. Examples of sulfonylureas include, but are not limited to, chlorsulfuron; chlorimuron-ethyl; nicosulfuron; primisulfuron; thifensulfuron; metsulfuron; sulfometuron-methyl; or bensulfuron- methyl. Examples of imidazolinones include, but are not limited to, imazaquin; imazethapyr; imazapyr; or imazamethabenz. An example of a triazolopyrimidine sulfonylanilide includes, but is not limited to, flumetsulam. In another embodiment, the aromatic carboxylic acid comprises a phenoxyacetic acid, a benzoic acid, or an aryloxyphenoxypropionate. Examples of phenoxyacetic acids include, but are not limited to, 2,4-dichlorophenoxyacetic acid (2,4-D); or 2,4,5- trichlorophenoxyacetic acid (2,4, 5-T). Examples of benzoic acids include, but are not limited to, dicamba or chloramben. Examples of aryloxyphenoxypropionates include, but are not limited to, diclofop-methyl; fluazifop-butyl; or quizalafop- ethyl. In another embodiment, the chloroacetamide comprises alachlor; metolachlor; propachlor; butachlor; diphenamide; napropamide; pronamide; propanil; or acetochlor. In another embodiment, the triazine comprises a chlorinated s-triazine; a methoxy s-triazine; a methylthio s-triazine; or an asymmetrical triazine. Examples of chlorinated s-triazines include, but are not limited to, atrazine; cyanazine; cyprozine; simazine; procyazine; or propazine. Examples of methoxy s-triazines include, but are not limited to, atraton; prometon; secbumeton; or simeton. Examples of methylthio s-triazines include, but are not limited to, ametryn; prometryn; terbutryn; simetryn; or desmetryn. An example of an asymmetrical triazine includes, but is not limited to, Metribuzin. An example of an ESPSase inhibitor includes, but is not limited to, glyphosphate. In another embodiment, the ACCase inhibitor comprises an aryloxyphenoxypropionate or a cyclohexenone. Examples of aryloxyphenoxypropionates include, but are not limited to, diclofop-methyl; fluazifop-butyl; or quizalafop-ethyl. Examples of 33 cyclohexenones include, but are not limited to, sethoxydim; clethodim; alloxydim; or cycloxydim. In another embodiment, the dinitroaniline compound comprises a methylaniline herbicide or a sulfonylaniline. Examples of methylaniline herbicides include, but are not limited to, trifluralin; pendimethalin; benefin; dinitramine; fluchloralin; or profluralin. Examples of sulfonylaniline compounds include, but are not limited to, oryzalin or nitralin. In another embodiment, the halohydroxybenzonitrile comprises bromoxynil or ioxynil. In another embodiment, the isoxazolidone comprises clomazone.
The amount of the agricultural additive that can be incoφorated into the matrix system can vary depending upon the agricultural additive and the rate of release of the additive. In one embodiment, the agricultural additive comprises from 0.1 to 50 % by weight, preferably from 0.1 to 30 % by weight, more preferably, from 0.1 to 20 % by weight of the matrix system.
The controlled release matrix system containing an agricultural additive can be disposed by techniques known in the art for the administration of agricultural, garden, or lawn chemicals. The term "dispensing" is defined as a process of contacting or administering the controlled release matrix system of the present invention to a target. In one embodiment, the target can be a plant or soil. In another embodiment, the plant is an agricultural, garden or lawn plant.
The phrase "a period of time sufficient to undergo biodegradation and release the additive" refers to the time required to initiate release of the additive. The time can vary for the release of the additive from the controlled release matrix system, depending upon the biodegradable cellulose ester and additive used. Once the initial release of the additive occurs, the duration of release of the additive can also vary depending upon the cellulose ester and additive employed. The term "duration of release" is defined as the time required for substantially all of the 34 additive to escape the controlled release matrix system. The duration of release can be from days to years.
The applicants have also discovered that pharmaceutical additives can be incoφorated into the controlled release matrix system. Any pharmaceutical additive that is miscible with the biodegradable cellulose ester can be used in the present invention. Pharmaceutical additives useful in the present invention are disclosed in Physician's Desk Reference, which is herein incoφorated by reference.
Depending on the intended mode of administration, the controlled release matrix system comprising the pharmaceutical additive can be in pharmaceutical compositions in the form of solid, semi-solid or liquid dosage forms, such as, for example, tablets, suppositories, pills, capsules, powders, liquids, suspensions, lotions, creams, gels, or the like, preferably in unit dosage form suitable for single administration of a precise dosage. In addition, the controlled release matrix system may include other medicinal agents, pharmaceutical agents, carriers, adjuvants, diluents, etc.
For oral administration, fine powders or granules may contain diluting, dispersing, and/or surface active agents, and may be presented in water or in a syrup, in capsules or sachets in the dry state, or in a nonaqueous solution or suspension wherein suspending agents may be included, in tablets wherein binders and lubricants may be included, or in a suspension in water or a syrup. Where desirable or necessary, flavoring, preserving, suspending, thickening, or emulsifying agents may be included. Tablets and granules are preferred oral administration forms, and these may be coated.
Parenteral administration, if used, is generally characterized by injection. Injectables can be prepared in conventional forms, either as liquid solutions or 35 suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions.
The exact amount of the pharmaceutical additive will vary from subject to subject, depending on the species, age, weight and general condition of the subject, the severity of the disease, infection, or condition that is being treated or prevented, the particular pharmaceutical additive used, its mode of administration, and the like. Thus, it is not possible to specify an exact amount. However, an appropriate amount may be determined by one of ordinary skill in the art using only routine experimentation given the teachings herein. In one embodiment, the pharmaceutical additive is from 0.1 to .50 % by weight, preferably from 0.1 to 20 % by weight of the controlled release matrix system.
In one embodiment of the invention, the controlled release matrix system containing the pharmaceutical additive can be administered to a subject. In another embodiment of the invention, the subject is a mammal, reptile, bird or fish. In another embodiment, the subject can be a human or another animal, wherein the animal can particularly be a domestic, food producing or wild animal. Examples of domestic animals include, but are not limited to, dogs, cats, horses or birds. Examples of food producing animals include, but are not limited to cows, pigs, chickens or sheep. Examples of wild animals include, but are not limited to, lions, tigers, elephants, monkeys or bears.
The size and shape of the controlled release matrix system can vary depending upon the technique used to prepare the matrix system. In one embodiment, the matrix system can be a microcapsule or microsphere. In one embodiment, the microsphere is from 0.1 im to 500 im, preferably from 0.1 im to 100 im, and more preferably from 0.5 im to 5 im in diameter. In another embodiment, the matrix system can be a film, wherein the film has a thickness of from 3 mm to 250 mm or from 0.01 to 10 mils. In another embodiment, the matrix 36 system can be a fiber or a granule. In another embodiment, the matrix system can be a woven or spun fiber or a pelletized sphere or granule.
The invention further relates to a controlled release matrix system, comprising a homogeneous mixture of:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive or pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system.
The invention further relates to a controlled release matrix system, consisting essentially of a homogeneous mixture of:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive or pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system.
In another embodiment, a small amount of residual plasticizer or surfactant may be incoφorated into the controlled release matrix system.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be 37 accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at room temperature and pressure is at or near atmospheric.
EXAMPLES
General Procedures
The cellulose ester material used in the examples was taken from normal production either as final product or as a solution, sampled just prior to precipitation.
Throughout the Examples, the following terms will be used:
The haze point is defined as the point where the acid dope of a cellulose ester begins to biphase. The break point is the point where the cellulose ester solid phase appears. The haze and break points are dependent on the type of cellulose ester, hydroxyl content, temperature, percent acid and percent water of the precipitation mixture. For the puφoses of the Examples, PZ refers to plasticizer. Dope is defined as cellulose ester dissolved in solvent.
"DS/AGU" or simply "DS" refers to the number of substituents per anhydroglucose units where the maximum DS/AGU is three.
"AMU" refers to atomic mass units.
Cellulose ester types are included in the following table: vo tΛ (Λ
Properties of Selected Cellulose Esters
Melting
Viscosity Acetylc Propionyl Range τg °c
Type Sec Poise % % Hydroxyl °C
Cellulose Acetate Propionate
CAP 482-20 20.00 76.00 2.5 46.0 1.8 188-210 147 I
Lo
CAP 482-0.5 0.40 1.52 2.5 45.0 2.6 188-210 142 03
I
Cellulose Acetate
CA 398-30 30.00 1 14.00 39.7 — 3.5 230-250 189 CA 394-1 10 1 10.0 228.00 39.4 0 4.0 240-260 186
3
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39
Procedure (A)- Lab Scale Powder Precipitation
The following steps were taken to prepare lab scale powder precipitation cellulose ester blends with a functional additive incoφorated into the blend: (1) Cellulose ester dope samples were obtained and the solids, percent acid, acid ratio, and percent water were measured. (2) The functional additive or additive package was added and incoφorated into the ester dope either by rolling on a bottle roller or by mixing with a stirrer and paddle mixer. (3) The dope mixtures were placed into a thermostated bath to equilibrate to the desired temperature. (4) The dope mixtures were precipitated with a mechanical stirring in a stainless steel beaker
(turbo) which had three equally placed vertical fins arranged to promote mixing and turbulence of a stirred solution. The turbo was placed in a thermostated bath which was placed in a laboratory hood. (5) The precipitations all used dilute aqueous acetic acid, or dilute aqueous mixed carboxylic acid solutions as the precipitant. (6) The precipitated materials were washed using tap-wash filter bags with deionized water at temperatures between 24 and 33 °C. (7) Then 0.01 weight% potassium dihydrogen citrate was added by spraying wet ester in bag with the correct amount of a 0.15 weight% aqueous solution of potassium dihydrogen citrate by utilizing an atomizer bottle. (8) The washed and stabilized materials were dried in a forced air oven.
Procedure (B)-Lab Scale Pellet Precipitation
The following steps were taken to prepare lab scale pellet precipitated cellulose ester blends with a functional additive incoφorated into the blend: (1) Ester samples were obtained and the solids, percent acid, acid ratio, and percent water were measured. (2) The functional additive or additive package was added and incoφorated into the ester dope either by rolling on a bottle roller or by mixing with lab stirrer and paddle mixer. (3) The dope mixtures were placed into a thermostated bath to equilibrate to the desired temperature and the pelleter was placed into a forced air laboratory oven to equilibrate to the desired temperature. 40
(4) As quickly as possible the pellet maker was removed from the oven, the dope was added to the pellet maker and the remaining pellet maker parts were assembled. (5) The pelleter was placed with the cutter end submerged in the precipitation bath, air pressure and cutter drive were set and pellets were formed. The pellets were precipitated into water or dilute aqueous acetic acid. (6) The pellet precipitated materials were washed. (7) The pellets were stabilized by soaking the washed pellets in an 0.06 weight% aqueous potassium dihydrogen citrate solution and draining away the excess solution. (8) The washed pellets and stabilizer were dried in a forced air oven.
Procedure for the Encapsulation of an Agricultural or Pharmaceutical Additive into a Cellulose Ester Microsphere (See Table 14 and Example 10)
A solution of a cellulose ester is prepared by dissolving the desired cellulose ester in an appropriate water-immiscible organic solvent. The organic solvent may be any one of a number of organic solvents, preferably one that dissolves the cellulose ester and the agricultural or pharmaceutical additive, has limited water solubility, and which forms a low-boiling point azeotrope with water. To the solution of the cellulose ester is added the desired amount of the additive. The solution is stirred until the active material dissolves completely.
The percentage of the active material in the final product is calculated by dividing the weight of the active by the sum of the weights of the active material and the cellulose ester. The percentage of additive in the cellulose ester may vary from 0.1 weight % to 50 weight %. The maximum weight percent of active material incoφorated into the cellulose ester may be determined experimentally by increasing the weight percent of active material in the mixture until the active material begins to form a separate phase.
A known quantity of surfactant is weighed into a second beaker and water is added to make an aqueous solution of the surfactant. The cellulose 41
ester/additive/organic solvent mixture is added to the aqueous solution of surfactant prepared while stirring in a high shear mixer. The solution is stirred to form an emulsion of the organic phase dispersed in the aqueous phase. The mixer should have sufficient "shear" to form droplets that range in size from sub-micron to less than 500 microns. Samples may be removed and examined via microsopy to determine when the particle size has reached a desired level.
The emulsion is transferred to a vessel equipped with a heat source, stirrer, and a distillation apparatus. The emulsion is heated to allow the organic solvent/water azeotrope to distill from solution. As phase separation of the distillate occurs, the aqueous layer is removed and returned it to the vessel. As the organic solvent is distilled from the emulsion, the vessel temperature will begin to rise. When the vessel temperature begins to rise, discontinue heating of the vessel and reconfigure the apparatus to continue the distillation under vacuum and apply heat to the flask to maintain the temperature of the contents of the vessel and continue distilling until the distillate is only water. Release the vacuum and discontinue heating the vessel. Allow the contents of the vessel (cellulose ester/additive- microspheres suspended in water) to cool to room temperature.
The cellulose ester/additive particles can be recovered by a number of techniques including centrifugation or filtration under vacuum. The microspheres may be dried in a vacuum oven at a temperature that will remove the residual water from the particles but will not cause the particles to melt or decompose.
Procedure for Melt-Blending of a Cellulose Ester and an Agricultural or Pharmaceutical Additive
A cellulose ester, an additive and, optionally, a plasticizer were mixed in a jar. The mixture was transferred to a melt blender. The temperature of the melt blender is increased and the mixture is agitated until the sample becomes homogeneous. The temperature at which the sample begins to melt is dependent on 42
the physical properties (melting point, Tg) of the individual materials or the blend of materials as well as the temperature of the melt blender and the amount of material placed in the melt blender.
When the instrument indicates that the torque required to mix the sample has reached a minimum and is constant, the blending is discontinued. The sample is discharged from the mixer as soon as it begins to harden.
Procedure for the Preparation of a Film or Fiber of Cellulose Ester and an Agricultural or Pharmaceutical Additive
Film may be prepared by thermal extrusion using either a melt-blended or an admixture of the cellulose ester, additive, and optionally , a plasticizer, for example, on an extruder with a film die, or by simultaneous pressing and heating on a press plate.
Procedure for Spray-Drying Materials with a Cellulose Esters
A cellulose ester and an additive are dissolved or suspended in a suitable organic or aqueous solvent. The solvent should be capable of dissolving or suspending both the cellulose ester and the biologically active material of interest. The solution is then atomized and dried in the spray dryer using techniques known to those skilled in the art of spray drying.
Example 1
Preparation via Lab-Scale Powder Precipitation
Eleven batches were produced by procedure (A) in a designed experiment to examine the effects of dope solids, precipitant acid concentration, and agitator speed on plasticizer retention. 43
The plasticizer content of all samples was measured by 'HNMR NMR was also used to determine DS propionyl. The molecular weight (weight avg.-Mw) was determined by size exclusion chromatography. Results are reported as polystyrene equivalent molecular weight. The plasticizer used for this example was 90 weight% - dioctyl adipate (DOA) and 10 weight% - triethylene glycol -2- ethylhexanoate. The precipitated powders were washed 45 minutes with deionized water and dried in a forced air oven at 60 °C for 16 hours. The high number of 100+ % retention values was attributed to bias in dope solids determination. Filterable solids in the liquids separated from the precipitated powders ranged from 0.001 to 0.008 weight percent and dissolved solids ranged from 0.030 to 0.097 weight percent. The filtrate ranged from 20-22 weight% acetic acid and 10-1 1 weight% propionic acid by GC analysis. These powders were not stabilized, but when 15-20 g of the powders were placed individually into a 70 mm diameter mold and pressed at 175 psig at a temperature range of 160 to 170°C for 10 minutes, they molded into slightly yellow but clear disks. PPT is defined as precipitate or precipitation herein.
44
Table 1: Example 1
Data Set 1
Sample # Dope ppt acid Agitator Temp
A Solids Concentration Speed
(wt%) (wt%) (rpm) (°C)
1 11 30 1500 58
2 7 10 500 58
3 1 1 10 1500 58
4 9 20 1000 58
5 7 30 500 55
6 9 20 1000 58
7 7 10 1500 59
8 7 30 1500 59
9 1 1 30 500 58
10 1 1 10 500 59
11 9 20 1000 56
45
Table 2: Example 1
Data Set 2
Sample # PZ PZ PZ DS Molecular
A Added by NMR Retained propionyl weight by NMR (wgt avg)
(wt%) (wt%) (wt%) AMU
1 11.46 10.31 90 2.73 2.49xl05
2 11.32 10.84 96 2.78 2.53xl05
3 11.26 1 1.29 100 2.69 2.54xl05
4 11.21 NO DATA NO DATA NO DATA 2.30xl05
5 11.1 1 8.06 73 2.8 2.37xl05
6 11.40 11.38 100 2.62 2.66xl05
7 1 1.02 12.5 113 2.61 2.51xl05
8 1 1.29 12.37 110 2.67 1.88xl05
9 11.40 13.39 117 2.76 2.57xl05
10 11.36 11.14 98 2.65 2.46xl05
1 1 11.19 11.6 104 2.67 2.51xl05
46
Example 2
Twenty two batches were produced by procedure (A) in a 5 factor designed experiment, utilizing CAP 482-20 (cellulose acetate propionate) and DOA. The factors are described in Table 3 and results are given in Table 4 with the amount of DOA remaining in the filtrate given in ppm. The washing and drying conditions are the same as Example 1. The trial was designed to examine the affects of the acid concentration used to lower the precipitation mixture to the break point, the acid concentration used to lower the precipitation liquids acid concentration after the break point, agitator speed, additive amount, and time to lower the acid concentration to the break point on the retention of DOA. The results of this trial indicated that the model for retention was dominated by the additive amount variable. High retentions of DOA were obtained and DOA measurements by GC and NMR correlated to an r2 of 0.9792. GC analysis of precipitation liquids showed amounts of DOA in the 3 to 72 ppm range.
47
Table 3: Experimental Design for
Example 2
Sample B Temp. Break Dilute Agitator Additive Time
Point wt% Speed amt. to wt% Acid Break
Acid Point
1 +-++-+ 1 -1 1 1 -1 1
2 0 0 0 0 0 0 0
3 ++--++ 1 -1 -1 1
4 -+--+- -1 1 -1 -1 -1
5 0 0 0 0 0 0 0
1 Q^1 11 11 11 11 11 11 1 1 1
7 _.+_++ -1 -1 1 -1 1
8 0 0 0 0 0 0 0
9 +-+.+- -1 1 -1 -1
10 + — + -1 -1 -1 -1 1
1 1 — +++ -1 -1 -1 1
12 -+-+-+ -1 1 -1 -1 1
13 0 0 0 0 0 0 0
14 .++..+ -1 1 1 -1 -1 1
I I DC - 11 11 11 11 - -1 1 1 -1
16 ++-+-- 1 -1 -1 -1
17 0 0 0 0 0 0 0
18 +-++- -1 -1 -1
19 +++— 1 1 -1 -1 -1
20 0 0 0 0 0 0
21 --++-- -1 -1 1 -1 -1
22 -1 -1 -1 -1 -1 -1
Design -1 40 °C 25 wt% 5 wt% 500RPM 4 wt% lMTN
Unit 0 50 °C 30 wt% 10 1000RP 8 wt% 2MTN
Value 1 60 °C 35 wt% wt% M 12 wt% 3MTN
15 1500RP wt% M 48
Table 4: Example 2 Data
Sample B Theor. Percent Percent Precipitation
Percent DOA DOA Liquids
DOA Measured Retained ppm DOA
1 4.27 3.92 91.73 5.7
2 8.53 8.13 95.35 12.8
3 12.75 10.84 85.05 14
4 12.75 1 1.27 88.42 9.3
5 8.53 8.25 96.76 39.5
6 12.75 1 1.94 93.68 56.8
7 12.36 10.57 85.52 67.7
8 8.26 7.15 86.59 8.4
9 12.36 10.48 84.79 72.4
10 4.13 3.57 86.39 4.1
11 12.36 11.43 92.47 22.9
12 4.13 3.92 94.86 2.6
13 8.26 7.29 88.29 61.1
14 4.13 3.41 82.52 7.3
15 12.36 1 1.5 93.04 63.8
16 4.13 4.12 99.7 24.8
17 8.26 7.1 1 86.1 1 22.3
18 12.36 11.22 90.78 14.3
19 4.13 3.65 88.33 21.1
20 8.26 7.11 86.11 23.5
21 4.13 4.1 1 99.46 17.4
22 4.13 3.47 83.97 3.1
49
Example 3
Batches produced by procedure (A) using CAP482-20 and A2 polyester (polyethylene succinate - 2.4596 xlO number avg. molecular weight ; 0.553 dL/g IV ). These several batches demonstrated moderate retention when A2 polyester is coprecipitated with CAP482-20. Conditions and results are in Table 5.
Samples C 1 to 4 were precipitated at 60°C and 1000 φm agitator speed using deionized water containing 21 weight. % acetic acid, 11 weight. % propionic acid, in deionized water. Final filtrate acid concentrations were adjusted to approximately from 34 to 36 weight percent acid as acetic by addition of deionized water to the turbo after break point concentration was reached. Dilute acid addition time was from 6.5 to 7.5 minutes. Dissolved solids were separated from the filtrate acid by evaporation and sent for NMR analysis as Sample D. This analysis showed that only A2 polyester was present. Samples E 1 to 4 were precipitated using 13.4 weight% acetic acid and 6.6 weight% propionic acid in deionized water. Final filtrate acid concentrations were adjusted to approximately from 25 to 30 weight percent acid as acetic by addition of deionized water to the turbo after break point concentration was reached. Dilute acid addition time was from 6.5 to 7.5 minutes. Samples were washed and dried. Samples molded from this example produced hard, hazy clear, white plastic disks. Although A2 polyester is not miscible with CAP, the molded disks show that the polyester was dispersed evenly in the CAP blend.
50
Table 5: Example 3 Data:
Sample: C-l to 4 E-l to 4 ppt Temperature: 60 °C 60 °C
Agitator Speed: 1000 RPM 1500 RPM
Washing Time: 35 min. 45 min.
Drying Time: 12-16 h 16 h
Dry. Temperature: 60 °C 60 °C
Results:
Sample # Theoretical Measured Percent Filterable Dissolved
Weight Weight Retained Solids Solids
% A2 % A2 wt % wt % NMR
C-l 9.2 3.4 36.5
C-2 16.1 8.9 55.1
C-3 22.5 8.7 38.6
C-4 26.2 12.5 47.7
E-l 10.8 5.2 48.1 0.06 0.10
E-2 16.1 9.0 55.9 0.11 0.14
E-3 21.2 12.7 59.9
E-4 31.9 20.4 63.9 0.18 0.17
51
Example 4
Four batches were produced by Procedure (A) with polyester plasticizers. Batches one to three, Samples F 1 to 3, were CAP482-20 coprecipitated with Admex 523® plasticizer produced by Huls America, which is described as a copolymer of phthalic acid, 1,3-butanediol, and 1,4-butanediol -end-capped by aliphatic epoxide. Batch four, Sample G was CAP482-20 coprecipitated with Plastolein 9765® produced by Henkel Coφ., which is described as a copolymer of phthalic acid, 1,2-propanediol, and another diacid. Retention data was obtained by producing two calibration curves of CAP482-20 mixed with varying concentrations of these plasticizers respectively. The ratio of aromatic to backbone protons versus weight percent plasticizer produced linear calibration curves with r2 (correlation coefficient) of 0.99266 for Plastolein 9765 and 0.99945 for Admex 523. Final precipitation liquids acid concentrations were from 25 to 28 weight% (as acetic).
These batches produced a yield of 90 to 95 % (based on ester solids and plasticizer weight) of a soft powder precipitate when 20 g was pressed at 175 to 200 psig at 170°C in a 7 cm diameter mold, and the resulting disks were clear, with no color and hard, smooth surfaces.
Batch four makeup was 9.7 weight percent Plastolein 9765, however, measurement by NMR found 18.6 percent Plastolein. During precipitation of this batch a large amount of stringy precipitated fibers gathered around the stirrer. A lesser amount of very fine precipitated powder, similar to the powder from Samples F 1 to 3 was produced. When 20 g was pressed at 175 psig and 169.5°C in a 7 cm diameter mold, the resulting molded disk was hard and clear but yellow in color.
52
Table 6: Example 4 Data
Sample: F-l to 3 G-1
PPT Temperature: 43-49 °C 43-49 °C
Agitator Speed: 1500 RPM 1500 RPM
Washing Time: lh @28 °C lh @28 °C
Drying Time: 16 h 16 h
Dry. Temperature: 60 °C 60 °C
Results:
Sample # Theoretical Measured Percent
Weight Weight Retained
% Additive % Additive
NMR
F-l 20.6 21.4 103.9
F-2 9.4 8.8 96.6
F-3 9.4 7.7 81.9
G-1 9.7 18.6 ***
53
Example 5
Two batches of CAP482-20 were coprecipitated with F2 polyester (polyethylene glutarate, 0.5 IV). Batch one was precipitated by Procedure (A) under conditions similar to Example 4, with the exception that the CAP482-20 dope was 11.4 weight percent of CAP482-20 powder in solution with 26.6 weight. % water, 41.4 weight% acetic acid and 20.6 weight% propionic acid (artificial dope). To this dope, F2 polyester was added and brought to 49°C. The mixture was rolled on a bottle roller for 1 hour to distribute F2 polyester in the artificial CAP dope. This mixture was 13.3 weight percent F2 polyester (based on ester solids weight and F2 weight). Precipitation of this material resulted in a 91.3 % yield of powder and extremely clear precipitation liquids.
Batch two was precipitated in a dope bucket turbo by Procedure (A) The CAP482-20 dope (12 weight percent CAP with 15 weight percent F2 polyester) was precipitated at 43°C using an aqueous solution containing 24 weight% acetic acid to 12 weight% propionic acid. The precipitate was washed with deionized water. The yield of powdery product was 74.7 %. One kg of the dry precipitate was pelletized. The pellets were clear and slightly yellow. NMR analysis of this coprecipitated material revealed 10 1 weight% F2 polyester, which is 67.3 % retention. F2 polyester remained on the stirrer blades and sides of the dope bucket after the precipitate was transferred into the wash bag, which contributed to the low retention value.
Example 6 Four Batches, Samples H 2 to 4 and Sample 1-1, of CAP482-20 were coprecipitated with dioctyl adipate plasticizer in a single blade mixer, by a procedure similar to procedure (A), for comparison testing of plastic properties. The dope mixture was brought to the break point with 35 weight% mixed acetic / propionic acid (2:1 acid ratio) and then 10 weight% mixed acid was used to further reduce the acid concentration. The resulting powder was water washed for 10 hours, centrifuged and vacuum dried These batches were pelleted. Sample H-l is
SUBSTΓΓUTE SHEET (RULE 26) 54
a comparison sample from standard thermal blending of CAP482-20 with 12 weight% DOA plasticizer in a twin-screw extruder. The physical property values compare favorably to values for CAP482-20 thermally compounded with DOA.
Table 7: Example 6 Data
Sample H-2 H-3 H-4 1-1
PPT Temperature: 43 °C 43 °C 43 °C 43 °C Dope Solids: 11.90 wt % 11.85 wt % 11.90 wt % 11.04 wt % Agitator Speed: 300 RPM 125 RPM 100 RPM 120 RPM Washing Time: lOh lOh lOh lOh Drying Time: 12h 12h 12h 12h
Results:
Sample # Theoretical Measured Percent wt % wt % Retained
DOA DOA GC
H-2 17.2 20.2 117.4 H-3 19.1 22.0 115.2 H-4 18.9 18.8 99.5 1-1 7.3 7.1 97.3
Precip. Precip. Precip. Percent
Liquids Liquids Liquids Yield wt % wt % ppm of acetic acid propionic DOA DOA acid
H-2 21.3 8.1 260 74.4 H-3 24.2 13.3 140 63.3 H-4 14.1 6.5 160 NR 1-1 29.6 16 360 67.7 55
f Batches produced in Example 6
Notched Un-
Izod notched
Impact Izod Flex Flex Flex Flex
Strength Impact Yield Yield Yield Yield
Strength Strain Strain Stress Stress
@-40°C @-40°C % % MPa MPa ftlb/in J/m ftlb/in J/m mean std mean std dev dev
H-l 1.8 27.9 41.2 2199.1 4.839 0.152 42.0 1.0 H-2 4.9 263.0 21.4 1141.4 3.782 0.081 23.9 0.0 H-3 4.0) 215.5 3.0 157.5 3.657 0.081 22.3 0.1 H-4 4.002 0.118 26.0 0.1 1-1 5.621 0.310 54.5 0.5
Flex Flex Offset Offset
Modulus Modulus Yield Yield Yield Yield Yield Yield
Stress Stress Stress Stress Strain Strain
MPa MPa MPa MPa MPa MPa % % mean std dev mean std mean std mean std dev dev dev
H-l 1587 85 41.979 1.000 35.0 1.1 4.4 0.1 H-2 968 23 23.608 0.062 20.6 0.2 3.8 0.1 H-3 949 13 21.924 0.051 19.4 0.3 3.8 0.1 H-4 1066 18 25.780 0.106 22.5 0.2 3.9 0.1 1-1 1887 48 53.894 0.410 42.5 0.4 4.9 0.2
Break Break Break Break Rockwell Rockwell Stress Stress Strain % Strain Hardness Hardness MPa MPa mean % R scale R scale mean std dev std mean std dev dev
H-l 33.2 2.9 21.6 3.3 84.4 0.55 H-2 22.0 0.3 44.2 1.4 18.2 6.83 H-3 20.6 0.2 42.4 1.7 6.6 2.07 H-4 22.3 0.2 35.6 2.4 28.6 8.02 1-1 41.0 3.4 24.0 8.1 100.6 0.89 56
Example 7
Lab scale batches were precipitated by procedure (A) using CA398-30 and screening the following plasticizers: dioctyl phthalate (DOP), diethyl phthalate (DEP), Monsanto Santicizer 160® (butyl benzyl phthalate (BBP)), Admex 523, triethyl citrate (TEC), tripropinoin, Benzoflex 400® (polypropylene glycol dibenzoate), A2 polyester, F2 polyester, sucrose acetate isobutyrate (SAIB), triphenyl phosphate (TPP), polyalkyl glycoside (Glucopon 600®), triethyl phosphate and Eastman 240® plasticizer containing 72 weight% diethyl phthalate, 22 weight% dimethyl phthalate and 6 weight% 2,2,4-trimethyl-l,3-pentane-diol diisobutyrate.
Table 9 contains data from batches that gave good plasticizer retention but poor thermal plasticization. They did not show indications of plasticization and molding when 20 grams of the coprecipitated powder were pressed on a 7 cm diameter mold at 175 psig and heated from 150 to 168°C in 10 minutes. The sample batches all produced clear precipitation liquids, indicating high retention of the additive with the cellulose ester, based on work with CAP482-20. The percent yield of dry powder indicated yields of from 89-98 %, based on the total weight of cellulose ester plus additive. Sample L-4 was analyzed by NMR spectroscopy for BBP retention, and was found to have a retention of 125 weight%. Sample L-4 also had the highest yield of 98 % indicating excellent retention.
Table 11 contains data from batches that gave good plasticized retention but poor thermal plasticization. They did not show indications of plasticization and molding when 20 grams of the coprecipitated powder were pressed on a 7 cm diameter mold at 175 psig and heated from 150 to 168°C in 10 minutes. The sample batches all produced hazy precipitation liquids, indicating possible low retention of the additive or dissolved ester solids, based on work with CAP482-20. Percent yield of dry powder was calculated, based on the total of ester solids plus additive weight. Only DOP and SAIB produced high yields, which indicated good additive retention. Example 7 batches demonstrate that water solubility of the 57
coprecipitated functional additive has a major effect on additive retention as shown by the zero retention of TEC. Other indications of the importance of additive water solubility are given by the low percent yields for DEP, triethyl phosphate and Eastman 240 (see Table 10 for water solubilities). Diethyl phthalate (DEP) and dimethyl phthalate (DMP) have been shown to have azeotropes with water and azeotropic losses in drying may be the reason for the low retention of the DEP and Eastman 240. Another reason for the low retention in Eastman 240 may be attributed to the solubility properties of dimethyl phthalate. Also, the Hildebrand solubility parameters (a -(cal cm3)1/2) for DEP and DMP are 10.0 and 10.7 respectively, and both have a medium H-bond index. The examples shown here seem to indicate that plasticizers or additives with Hildebrand solubility parameters less than 10.0 are better candidates for coprecipitation. Dioctyl adipate (DOA) and dioctyl phthalate (DOP) both have high retentions in coprecipitation trials and their Hildebrand solubility parameters are 8.7 and 7.9 respectively. Both DOA and DOP have a medium H-bond index. Triphenyl phosphate will coprecipitate with
CAP482-20. The yield of the compounded product (ester and plasticizer) was 90 weight%, with 86.7 weight% retention of plasticizer (13 weight% TPP - lost to the filtrate). The TTP has a Hildebrand solubility parameter of 9.0 and is not water soluble. Triethyl phosphate, which is miscible in water when coprecipitated with CA398-30, produces a 68.7% yield and a calculated zero percent retention (based on yield). This example demonstrates the retention of additives that have a range of solubility with respect to the cellulose acetate.
58
Table 9: Example 8 Data
Sample: J-5 L-l L-2 L-3 & 4
PPT
Temperature: 38 °C 35 °C 35 °C 38 °C
Dope Solids: 10.76 wt % 10.75 wt % 10.75 wt% 10.75 wt %
Agitator Speed: 1500 RPM 1500 RPM 1500 RPM 1500 RPM
Washing Time: 35 min. 35 min. 35 min. 35 min.
Drying Time: 12h 12h 12h 12h
Dry. Temperature:
60 °C 60 °C 60 °C 60 °C
Results:
Sample # Theoretical Measured Percent wt % wt % Retained Plasticizer
Plasticizer Plasticizer
NMR
J-5 12.0 ND (not Admex 523 determined)
L-l 30.0 ND A2
L-2 30.0 ND F2
L-3 30.0 ND Benzoflex 400
L-4 30.0 37.5 125 BBP
Precip. Liquids Percent Yield Based on wt % Dry Solids acetic acid
J-5 22.0 89.0
L-l 20.5 90.0
L-2 20.5 89.0
L-3 20.0 94.0
L-4 20.0 98.0
59
Table 10: Solubility Data
Plasticizer Water Solubility at 20 °C
DEP 0.012 wt. %
DMP 0.43 wt %
DOP 3.4 x lO-5 wt. %
DOA 7.8 x 10-5 wt. %
TEC 6.90 wt. % tripropinoin Negligible
TPP 0 wt. %
TEP 100 wt. %
Eastman 240 Negligible
60
Table 11: Example 7 Data
Sample: M-l to 5 N-1 & 2
PPT Temperature: 35-37 °C 33 °C
Dope Solids: 11.14 wt % 10.95 wt % -
Agitator Speed: 1500 RPM 1500 RPM
Washing Time: 35 min. 35 min.
Drying Time: 16h 16h
Dry. Temperature: 60 °C 60 °C
Results:
Sample # Theoretical Precip. Percent wt % Liquids Yield Plasticizer
Plasticizer wt % Based on acid Solids of
(CE
&
Plasticizer)
M-l 12 16 94.5 DOP
M-2 30 16.1 86.9 DOP
M-3 30 16.2 69.2 Eastman 240
M-4 30 16.7 66.9 tripropinoin
M-5 30 16.1 68.7 triethyl phosphate
N-l 25.1 16.2 90.1 SAIB
N-2 25.5 16.1 63 Glucopon 600
61
Example 8
Cellulose acetate CA398-30 was coprecipitated by procedure (A) containing BBP plasticizer and C.I. Solvent Violet 13 Dye.
The two cellulose acetate batches Rl and R3 were molded in a 7 cm round mold into hard smooth opaque disks. The cellulose acetate propionate Batch SI was soft and sticky, even after washing and drying. Batch SI did mold very well at only 160 °C. The disk was hazy but uniformly blue and very flexible and after two weeks of handling and room temperature storage had retained its weight. This example demonstrates coprecipitation of a dye in cellulose acetate and again demonstrates retention of immiscible additives in a cellulose acetate matrix formed by coprecipitation. This example also demonstrates retention of high loading of additive.
SUBSTITUTE SHEET (RULE 25) 62
Table 12: Example 8 Formula Data
Sample: R-l & R-3 S-l
PPT Temperature: 26 °C 26 °C Dope Solids: 10.76 wt% 10.60 wt% Agitator Speed: 1000 RPM 1000 RPM Washing Time: 35 min. 35 min. Drying Time: 16h 16h Oven Temp.: 60 °C 60 °C Cellulose Ester Type: CA398-30 CAP482-20
Makeup Percent Percent BBP CL
Solvent
Violet 13
R-l & R-3 10 0
S-l 35 0.041
Results Precip.
Liquids
Percent Percent
Percent Percent BBP Acid as
BBP Cl. Retained Acetic
Solvent Violet 13
R-l 8.0 80.0 29.5
S-l 34.1 0.041 97.5 26.0
63
Example 9
This example describes the results of coprecipitation of CA398-30 and CA394-110 cellulose acetate acid dopes as pellets by procedure (B). In trials with cellulose acetate described in the earlier examples, the additives which retained well did not always plasticize the cellulose acetate. Plasticizers which do plasticize the cellulose acetate have not been demonstrated in previous examples to retain to a suitable level in powder precipitates, due to excessive water solubility. The puφose of these trials was two fold: first, to demonstrate the ability to coprecipitate the cellulose acetate and functional additive product in pellet form, and secondly to demonstrate the ability to coprecipitate cellulose acetate with a more water soluble, more polar plasticizer which would produce a plasticized cellulose acetate product and demonstrate the ability to increase retention of the more water soluble additives in the cellulose ester. Pellet precipitation was chosen, since pellets have less surface area per volume than powders, which would reduce the surface area of the particles, limiting the area available for diffusion of the additive out of the matrix.
Sample disks from Sample T-l and Sample V-l were molded in a 7 cm round mold at the conditions described in Example 7. Both Sample T-l and Sample V-l molded into clear hard but very yellow disks, Sample T-l being yellower than Sample V-l from the retained acetic acid and salts. These batches demonstrated that retention of the more water soluble additives could be increased and that pellets could be coprecipitated.
64
Table 13: Example 9 Formula Data
Sample: T-l U-1 & 2 V-l V-2
PPT Bath Temp.: R.T. 21 °C 13 °C 11 °C
PPT Bath % Acetic
Acid: 0 wt% 0 wt% 8.6 wt% 6 t%
Dope Solids: 23.60 wt% 19.4 wt% 22.02 wt% 22.02 wt%
Dope % Acetic Acid: 61.20 wt% 56.5 wt% 62.0 wt% 62.0 wt%
Dope Temperature: 32 °C 22 °C 22 °C 28 °C
Pellet Mkr. Air
Press.: 2 psig 3 psig 3 psig 3 psig
Pellet Cutter Speed: High High High High
Bath Agitator Speed: 1000 RPM 1100 RPM 1300 RPM 1300 RPM
Washing Time: 45 min. Varied 120 min. 180 min.
Washing Temp.: 31 °C 27 °C 27 °C
Drying Time: 16h 16h 16h 16h
Oven Temp.: 60 °C 60 °C 60 °C 60 °C
Cellulose Ester Type:
Theoretical % DEP: CA398-30 CA394-110 CA394-110 CA394-110
26.0 35.4 30.4 29.5
Results Percent Percent
Percent DEP acetic acid
DEP Retained Retained
T-l 20.6 79.2
U-l washed 30 min. 32.5 90.9 0.63 washed 60 min. 30.2 84.4 0.52 washed 90 min. 31.2 87.2 0.23
U-2 washed 30 min. 27.7 87.6 0.28 washed 60 min. 30.9 97.6 0.32 washed 90 min. 26.8 84.7 0.2
V-l 23.8 78.4 0.085
V-2 25.2 85.0 0.045
SUBSTΓΓUTE SHEET (RULE 26) 65
Example 10. General procedure for the formation of cellulose ester microspheres containing a biologically-active material.
A solution of the cellulose ester is prepared by dissolving the desired cellulose ester in an appropriate water-immiscible organic solvent. The cellulose ester may be any one of a number of cellulose esters including cellulose acetates, cellulose acetate butyrates or cellulose acetate propionates of varying degrees of substitution of the ester and varying molecular weights. The organic solvent may be any one of a number of organic solvents preferably one that dissolves the cellulose ester of choice, dissolves the biologically active material of choice, has limited water solubility and which forms a low-boiling azeotrope with water.
A known amount of the cellulose ester/organic solvent solution is weighed out. The desired amount of the active material is added to the cellulose ester dissolved in the organic solvent. The active material is stirred until it dissolves completely.
The percentage of the active material in the final product is calculated by dividing the weight of the active material by the sum of the weights of the active material and the cellulose ester. The percentage of active material in the cellulose ester may vary from low (i.e. less than 1 weight per cent) levels to much higher levels (i.e. 50 weight per cent). The maximum weight per cent of active material incoφorated into the cellulose ester may be determined experimentally by increasing the weight per cent of active material in the mixture until the active material begins to separate from the mixture.
A quantity of surfactant is weighed into a second beaker and water is added to make an aqueous solution of the surfactant. The surfactant may be any number of commercially available water-soluble surfactants. The surfactant should show the ability to stabilize droplets of the organic phase in the aqueous media without allowing the droplets to coalesce or phase separation to occur. Preferentially the 66
surfactant belongs to a class of materials known as alkyl polyglycosides.
The cellulose ester/active material/organic solvent is added to the aqueous solution of surfactant while stirring with a high shear mixer. The solution is stirred during the entire addition to form an emulsion of the organic phase dispersed in the aqueous phase. The mixer should have sufficient "shear" to form droplets that range in size from sub-micron to less than 100 microns.
After the addition is complete, heat the contents of the vessel and allow the organic solvent/water azeotrope to distill from solution. Return any water that separates from the azeotrope to the vessel. The distillation may be conducted under reduced vacuum, if desired. Continue distilling until the distillate contains only water. When the distillation is complete allow the contents of the vessel (cellulose ester/active material-microspheres suspended in water) to cool to room temperature. See Table 14 for examples.
The cellulose ester/active material particles can be recovered by a number of techniques including centrifugation or filtration under vacuum. The microspheres may be dried in a vacuum oven at a temperature that will remove the residual water from the particles but will not cause the particles to melt or decompose.
Specific example of the formation of cellulose ester microspheres containing a bioactive material. Procedure for the incorporation of 2,4-dinitrophenol into CAP 482-0.5 microspheres.
A 10 % solution of CAP 482-0.5 in isopropyl acetate is prepared. A known amount of the cellulose ester/organic solvent solution is weighed out. 2,4-Dinitrophenol is added to the cellulose ester/isopropyl acetate solution in an amount ranging from 1 to 30 weight % of the active (based on the weight of CAP 482-0.5), in this case 10 % and the mixture is stirred until the dinitrophenol dissolves. A surfactant is 67
weighed into a second beaker and water is added to make an aqueous solution of the surfactant.
The cellulose ester/active material/organic solvent is added to the aqueous solution of surfactant prepared while stirring with a high shear mixer. The solution is stirred during the entire addition to form an emulsion of the organic phase dispersed in the aqueous phase. The contents of the vessel are heated and the organic solvent/water azeotrope is allowed to distill from solution. Return water that separates from the azeotrope after distillation to the vessel. Continue distilling until the azeotrope is completely removed and the solvent remaining in the vessel is only water.
When the distillation is complete, allow the contents of the vessel to cool to room temperature. The cellulose ester/active material particles can be recovered by a number of techniques including centrifugation or filtration under vacuum.
Example 11. General example of the coprecipitation of a bioactive material into a cellulose ester matrix.
A synthetic dope was prepared by combining the cellulose ester, acetic and propionic acids and water in proportions that mimicked a commercially prepared dope. To this mixture was added a biologically active material. The mixture was heated and stirred until the active material dissolved. The product was precipitated by the addition of solutions of acetic acid and water to the mixture. The solutions were made progressively more dilute in acetic acid until only water was added.
The product was isolated by filtration and the product was washed with water until the filtrate pH was neutral. The product was dried under vacuum and analyzed for presence of the active material. See Table 14 for Examples A - H. 68
Specific example of the coprecipitation of 2,4-dinitrophenoI into CAP 482-0.5
A CAP 482-0.5 dope was prepared containing 13% CAP 482-0.5, 16 % water 42 % acetic acid and 29 % propionic acid. 2,4-Dinitrophenol was added at 20% (vs. CAP 482-0.5) and the mixture was stirred until the phenol dissolved. The product was then precipitated by the addition of successive solutions of 35 % acid (in a 2: 1 ratio of acetic to propionic acid), 10 % acid (in a 2:1 ration of acetic and propionic acid) and water. The product was isolated by filtration and washed with water until the filtrate was neutral. The sample was dried in vacuo to yield a product which resulted in 28 % recovery of 2,4-dinitrophenol.
Table 14. Data for Examples 10 and 11. Incorporation of Biologically-Active Materials into Cellulose Esters by Various Techniques. vθ ϋ ini t
-4
4--
Example Cellulose Ester Active Technique Active level Weight % Yield CE- % Recovery (Theory) % Active(Actual) Active Matrix
A CAP 482-0.5 Mafenide Coprecipitation 10 0.45 7.9 g 3.6
B CAP 482-0.5 Mafenide Coprecipitation 20 0.34 11.7 g 1.6
C CA 398-30 Mafenide Coprecipitation 20 0.0 9.2 g 0.3
CO c D CAP-482-0.5 2,4-Dinitrophenol Coprecipitation 10 1.9 11.1 g 13.5 a E CAP 482-0.5 2,4-Dintrophenol Coprecipitation 20 5.9 12.0 g 28.0 ω F CA 398-30 2,4-Dintrophenol Coprecipitation 16 1.8 9.3 g 11.3
G CA 398-30 2,4-Dichlorophen- Coprecipitation 10 0.4 8.4g 4.0 oxyacetic Acid I en H CAP 482-0.5 2,4-Dinitrophenol Encapsulation 10 4.0 16.8 g 34.0 I x m q c m ro
O H
CΛ o 00 o
^1
70
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention wiH be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

71 What is claimed is:
1. A process for blending a cellulose ester with a functional additive, comprising:
(a) admixing the functional additive with the cellulose ester and a first acid; and
(b) contacting the admixture with an aqueous precipitating agent, whereby a blend comprising the cellulose ester and the functional additive coprecipitates.
2. The process of Claim 1, wherein the first acid is soluble in a selected solvent, the method further comprising prior step (b) admixing the first acid with the selected solvent.
3. The process of Claim 2, wherein the solvent is water.
4. The process of Claim 1, wherein the functional additive comprises a plasticizer, another polymer, a UN light stabilizer, a dye, a pigment, an acid stabilizer, a flame retardant, an agricultural chemical, a bioactive compound, or a mixture thereof.
5. The process of Claim 1, wherein the functional additive comprises a plasticizer, a UN light stabilizer, a dye, or a mixture thereof.
6. The process of Claim 4, wherein the additive comprises an agricultural chemical which comprises an insecticide, a pesticide, a herbicide, a fertilizer, a trace mineral, or a mixture thereof. 72
7. The process of Claim 4, wherein the additive comprises a plasticizer which comprises dioctyl adipate, triethylene glycol-2-ethylhexanoate, polyethylene glutarate, dioctyl phthalate, diethyl phthalate, butyl benzyl phthalate, triethyl citrate, tripropinoin, polypropylene glycol dibenzoate, polyethylene succinate, sucrose acetate isobutyrate, triphenyl phosphate, polyalkyl glycoside, triethyl phosphate, diethyl phthalate, 2,2,4-trimethyl-l,3-pentane-diol diiso-butyrate, a copolymer of phthalic acid, 1,3-butanediol, and 1,4-butanediol end capped by aliphatic epoxide, or a mixture thereof.
8. The process of Claim 1, wherein the cellulose ester comprises cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, cellulose propionate butyrate, or a mixture thereof.
9. The process of Claim 1, wherein the cellulose ester comprises cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate or a mixture thereof.
10. The process of Claim 1, wherein the degree of substitution of the cellulose ester is from 1.0 to 3.0.
11. The process of Claim 1, wherein the cellulose ester comprises cellulose acetate and the degree of substitution of the cellulose acetate is from 1.5 to 2.5.
12. The process of Claim 1, wherein the cellulose ester comprises cellulose acetate and the degree of substitution of the cellulose acetate is from 1.8 to 2.2.
13. The process of Claim 1, wherein the cellulose ester comprises cellulose acetate propionate and the degree of substitution of the cellulose acetate propionate is from 1.6 to 2.0 propionyl and from 0.1 to 0.5 acetyl. 73
14. The process of Claim 1, wherein the first acid comprises a carboxylic acid.
15. The process of Claim 1, wherein the first acid comprises acetic acid, propionic acid, butyric acid or a mixture thereof.
16. The process of Claim 3, wherein the first acid is from 60 to 90 % by weight and the water is from 2 to 15 % by weight of the admixture in step (a).
17. The process of Claim 3, wherein the first acid is from 10 to 90 % by weight acetic acid and from 10 to 90 % by weight propionic acid and from 0 to 30 % by weight water.
18. The process of Claim 3, wherein the first acid is from 10 to 90 % by weight acetic acid and from 10 to 90 % by weight butyric acid and from 0 to 30 % by weight water.
19. The process of Claim 1, wherein the functional additive is from 1 to 50 % by weight of the cellulose ester of step (a).
20. The process of Claim 1, wherein the functional additive is from 1 to 20 % by weight of the cellulose ester of step (a).
21. The process of Claim 1, further comprising warming the admixture of step (a) to 5 to 60°C prior to contacting the admixture with the precipitating agent.
22. The process of Claim 1, further comprising agitating the admixture of step (a) to disperse the functional additive prior to contacting the admixture with a precipitating agent. 74
23. The process of Claim 1, further comprising separating the precipitated cellulose ester / functional additive blend from the precipitating liquids.
24. The process of Claim 1, further comprising contacting the coprecipitated cellulose ester / functional additive blend with water.
25. The process of Claim 24, further comprising centrifuging the precipitate after contacting the blend with water.
26. The process of Claim 1, further comprising contacting the blend with a stabilizing agent which comprises one or more of potassium diydrogen citrate, sodium citrate, calcium citrate, sodium lactate, sodium oxylate, calcium acetate and sodium maleate.
27. The process of Claim 26, wherein the stabilizing agent comprises potassium dihydrogen citrate.
28. The process of Claim 26, wherein the stabilizing agent is from 0.01 to 1.0 % by weight of the precipitated cellulose ester / functional additive blend.
29. The process of Claim 1, further comprising drying the precipitated cellulose ester / functional additive blend by heating the blend.
30. The process of Claim 1, further comprising recovering the unprecipitated functional additive from the precipitation liquids.
31. The process of Claim 1, wherein the precipitated cellulose ester / functional additive blend is a powder.
32. The process of Claim 1, wherein the aqueous precipitating agent is water. 75
33. The process of Claim 1, wherein the aqueous precipitating agent comprises water and a second acid.
34. The process of Claim 33, wherein the first acid, the second acid or both are the conjugate acid of the ester group of the cellulose ester.
35. The process of Claim 33, wherein the second acid is soluble in water.
36. The process of Claim 33, wherein the second acid comprises a carboxylic acid.
37. The process of Claim 33, wherein the first and second acids are the same.
38. The process of Claim 33, wherein the first acid and second acid are not the same.
39. The process of Claim 33, wherein prior to the contacting step (b), the concentration of the first acid in step (a) is greater than the concentration of the second acid in the aqueous precipitating agent of step (b).
40. The process of Claim 1, wherein the amount of the aqueous precipitating agent is sufficient to dilute the concentration of the first acid in the admixture thereby causing the cellulose ester / functional additive blend to coprecipitate.
41. The process of Claim 33, wherein the second acid is from 10 to 40% by weight of the total weight of the aqueous precipitating agent.
42. The process of Claim 33, wherein the second acid is from 20 to 35% by weight of the total weight of the aqueous precipitating agent. 76
43. The process of Claim 42, wherein the second acid is from 1 to 39 % by weight acetic acid and 39 to 1 % by weight propionic acid of the total weight of the aqueous precipitating agent.
44. The process of Claim 41 wherein the second acid comprises a mixture of two or more of acetic acid, propionic acid and butyric acid.
45. A process for blending a cellulose ester with a functional additive, comprising:
(a) admixing i) a functional additive comprising a plasticizer, another polymer, a UN light stabilizer, a dye, a pigment, an acid stabilizer, a flame retardant, an agricultural chemical, bioactive compound or a mixture thereof;
ii) a cellulose ester comprising cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate or a mixture thereof; and
iii) a first acid comprising acetic acid, propionic acid, butyric acid or a mixture thereof; and
(b) contacting the admixture with an aqueous precipitating agent comprising water, acetic acid, propionic acid, butyric acid, or a mixture thereof, whereby a blend comprising the cellulose ester and the functional additive coprecipitates.
46. A process for preparing a cellulose ester/functional additive blend, comprising: 77
(a) admixing the functional additive with the cellulose ester and a first acid;
(b) depositing the admixture of step (a) in a pelleter;
(c) extruding the admixture from the pelleter;
(d) immediately after step (c) or simultaneous with step (c), contacting the extruded admixture with a precipitating agent to precipitate the cellulose ester/functional additive to thereby produce an extrusion of the cellulose ester/functional additive blend; and
(e) cutting the precipitated extrusion into pellets.
47. The process of Claim 46, wherein prior to step (b), the temperature of the admixture of step (a) is adjusted from -5 to 25°C.
48. The process of Claim 46, wherein prior to step (c), the temperature of the pelleter is adjusted to -5 to 25°C.
49. The process of Claim 46, wherein the precipitating agent is water
50. The process of Claim 46, wherein the precipitating agent comprises water and a second acid.
51. The process of Claim 46, wherein the precipitating agent is at a temperature of from -10 to 25°C.
52. A process for preparing a controlled release matrix system, comprising: 78
(a) admixing an agricultural additive or a pharmaceutical additive with a biodegradable cellulose ester and a first acid; and
(b) contacting the admixture with an aqueous precipitating agent, whereby a blend comprising the cellulose ester and the agricultural or pharmaceutical additive coprecipitates,
wherein the blend is a controlled release matrix system.
53. The product made by the process of Claim 52.
54. A method for controlled release of an agricultural additive comprising dispensing the controlled release matrix system, further comprising:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive,
wherein components (a) and (b) form a controlled release matrix system,
in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive.
55. The method of Claim 54, wherein the cellulose ester comprises cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate, cellulose acetate propionate, cellulose propionate butyrate or a mixture thereof. 79
56. The method of Claim 54, wherein the cellulose ester comprises cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or a mixture thereof.
57. The method of Claim 54, wherein the cellulose ester has a degree of substitution of from 1.0 to 3.0.
58. The method of Claim 54, wherein the cellulose ester is cellulose acetate with a degree of substitution of from 1.5 to 2.5.
59. The method of Claim 54, wherein the cellulose ester is cellulose acetate with a degree of substitution of from 1.8 to 2.2.
60. The method of Claim 54, wherein the cellulose ester is cellulose acetate propionate having a degree of substitution of from 0.1 to 0.5 acetyl and from
1.6 to 2.0 propionyl.
61. The method of Claim 54, wherein the cellulose ester is from 70 to 99 % by weight of the matrix system.
62. The method of Claim 54, wherein the agricultural additive comprises an insecticide, a herbicide, a pesticide, a fertilizer, a trace mineral, or a mixture thereof.
63. The method of Claim 62, wherein the agricultural additive comprises an insecticide, wherein the insecticide comprises an organochlorine compound, an organophosphate compound, an aryl compound, a heterocyclic compound, an organosulfur compound, a carbamate compound, a formamidine compound, a dinitrophenol compound, an organotin compound, a pyrethroid compound, an acylurea compound, a botanical compound, an antibiotic compound, a fumigant 80 compound, a repellant compound, an inorganic compound, or a mixture thereof.
64. The method of Claim 62, wherein the agricultural additive comprises a herbicide, wherein the herbicide comprises an ALSase inhibitor, an aromatic carboxylic acid, a chloroacetamide, a triazine, an ESPSase inhibitor, an ACCase inhibitor, a dinitroaniline compound, bentazon, a halohydroxybenzonitrile, a diphenyl ether, an isoxazolidone, paraquat, or a mixture thereof.
65. The method of Claim 54, wherein the agricultural additive is from 0.1 to 50 % by weight of the matrix system.
66. The method of Claim 54, wherein the agricultural additive is from 1 to 30 % by weight of the matrix system.
67. The method of Claim 54, wherein the matrix system is homogeneous.
68. The method of Claim 54, wherein the target is a plant or soil.
69. The method of Claim 54, wherein the matrix system is a microcapsule, a microsphere, a film, a fiber, or a granule.
70. The method of Claim 54, wherein the matrix system is a microsphere of from 0.1 to 500 im.
71. The method of Claim 54, wherein the matrix system is a film having a thickness of from 0.01 to 10 mils. 81
72. A method for controlled release of a pharmaceutical additive in the proximity of a target for the additive, comprising dispensing the controlled release matrix system, comprising:
(a) at least one biodegradable cellulose ester; and
(b) at least one pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system,
in the proximity of the target for the additive and for a period of time sufficient to undergo biodegradation and release the additive.
73. A controlled release matrix system, comprising a homogeneous mixture of:
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive or pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system.
74. The matrix system of Claim 73, wherein system further comprises a residual solvent and the residual solvent comprises acetic acid, propionic acid, or a mixture thereof.
75. The matrix system of Claim 74, wherein the residual solvent is from 0.005 to 0.5 % by weight of the matrix system.
76. A controlled release matrix system, consisting essentially of a homogeneous mixture of: 82
(a) at least one biodegradable cellulose ester; and
(b) at least one agricultural additive or pharmaceutical additive,
wherein components (a) and (b) form a controlled release matrix system.
EP99916652A 1998-04-24 1999-04-13 Coprecipitation of cellulose esters with functional additives and compositions thus obtainable Withdrawn EP1073693A1 (en)

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