CA1104496A - Rumen-stable pellets - Google Patents

Abstract

Abstract of the Disclosure Pellets adapted to be orally administered to ruminants are disclosed. The pellets have a core of a material beneficial to the ruminant such as a nutrient and/or medicament, and a coating which protects the core in the environment of the rumen, and allows utiliza-tion of the core in the abomasum and/or intestines. The coating comprises a polymeric matrix which is resistant to the mildly acidic environment of the rumen at pH of about 5.5 and a hydrophobic substance dispersed throughout the continuous matrix. The continuity of the polymeric matrix is destroyed in the more acidic environment of the abomasum.

Description

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Thls ~nventlon relates in ge eral to pellets adapted to be orally admini~teret to ru~nants and whic~ are benef~cial to ruminants after pasaing the rumen a~d reaching the abomasum ant/or i~testines.
More partlcularly, this invention relates to pellets havlng, in ter~s of ~tructure, a core material auch as a nutrient or medlcament, and an lmperforate coatirig over the core materlal which protect~ the core in the envlronmeDt of tbe ru~en, but which loses continulty under the more cltlc conditluns of the abomasum to renter the core material available for ut~llzation by the an$mal.

In ruminants, lngestet feed flrst passes into the rumen, where lt 1B pre-tlgested or tegratet by fermentation. Durlng this period of fermentatlon the lngestet feed may be regurgitated to the mouth via the reticulum where it is salivated and ruminated. After a period of fermen-tation regulated by natural processes and var$able depending on the an$mal and the feedstuff, adsorption of digested nutrients starts and continues in the subsequent sections of the digestive tract by the ruminant animal.
Thls process is described in tetail by D. C. Church, "Digestive Physiology ant Nutrition of Ruminants", Vol. 1, O.S.U. Book Stores, Inc., of Corvallis, Oregon.

The ru~en, the largest of the four st ach compartments of ruminants, serves as an important location for metabolic breakdown of ingested foodstuffs through the action of microorganisms which are preaent therein. Ingested food is typically retained in the rumen for from about 6 to 30 hours or longer in some instances, during which time lt ls sub~ect to metabollc breakdown by the rumen microorganisms. Much lngested protein material is broken town in the rumen to soluble peptides ant amino acits and utilizet by the rumen microorganisms. When the rumen contents pass into the abomasum and intestine, the mlcrobial mass i8 digested, thus proviting protein to the ruminant. ~hus, the natural 30 nutritlonal balance of the ruminant animal is primarily a funceion of the microbial co~position ant population.
In preparing nutrien~s ant medicaments lntended for adm$nistration , ~4~6 to ru~inants, lt ls i~portant to protect the active ingredients against the ~nvir~ental ccnditlon~ of the rumen, i.e., mlcroblal degrsdation ~nd the effects of a p~ of about 5.5, 80 the active substance will be ~aved untll lt reaches the partlcular locatlon where ataorptlon takes place. It ls well ~no~n th~t the rate of ~eat, wool and/or ~ilk pro-tuction can be increased lf sources of growth limiting eesential ~mino ~clds, and/or medlcaments, are protected from alteratlon by m~croorganlsms reslding in the ru~en and become avallable for direct absorption by the an~mal later in the gastrointestlnal tract.
Materlal~ whlch protect the core against degradation by the rumen contents ~hould be reslstant to attack by the rumen fluld whlch contains enZymeQ or mlcroorganisms but must make the active ingredient avallable rapidly ln the more acidic fluid of the abomasum at a p~
within the normal physlological range of about 2 to about 3.5. To more easily coat or encapsulate active ingredients in protectlve materials, the protective matertals should be soluble in certalr. organlc solvents for coating purposes.
Because proteins are sub~ect to breakdown in the rumen, it has been suggested that protein-containing nutrlents fed to ruminants be 20 treated 80 as to permit passage wlthout mlcroblal breakdow~ through the rumen to the abomasum. Syggested procedures have included coating the protein material, for e~ample, with fats and vegetable oils; heat treating of the proteln ~aterlal; reacting the proteln material wlth various compounts such as formsldehyde, acetylenlc esters, polymerlzed unsaturated carbo~ylic scld or anhytrldes and phosphonltrilic halltes, etc.
It is well known that all proteins found in animal ant plant life are chemical compounds containing tlfferent combln-tions of over 20 ~ino aclds, the number and arrange~ent of such aclts ~eing f~xed ln any partlcular protein. Twelve of these amino aclds can be synthesized in 30 nutritlonally adequate J~o~nts from other 6ub~tances by ~iochemlcsl proces~es normally pre~ent ~n 20st animals, but the remalnlng 10 essential smino acids are not ~ynthesized ~n sufficlent quantities and must be ingested by the ~nimal. Slnce the proportlons of the constituent ~mino acid~ in ~ partlcular protein cannot be var~et, the essenttal mino acld least n aupply limlta the amount of thst protein wh~ch can be produced by the ~nimal. Con~equently, for ~ny glven dlet, t~ere will be a parti-cular esseutial mino acld wh$ch llmlts the productlon of protein lncor-~orating that essentlal a~ino acid unless, of course, two or more such mino aclds are equally limlting.
The appreclatio~ of the above principles leads to the formula-tlon of diets for nonruminA~t animals whlch provlde the opt~ ~ proportlon 10 of amino aclds and have enabled ~lgn$flcant iacreases ln protein productlon to be achieved. In the ruminant, dietary protelns and amlno acids are~
to a varlable extent, brokeD down to ammonla and varlous organlc co~pounds by mlcroblal fermentaelon is the first two compartments of the stomach (the rumen and retlculum~. The bacterla and protozoa in these organs utlllze these metabolltes for thelr own growth and multiplicatlon and the mlcroblal proteln ~o formet passes on to the abomasum, the compart-ment of the stomach correspontlDg to the sto~ach of nonrumlnants, where lt 1B partlally tigestet. The process 19 completet ln the small intestine and the amino acids are absorbed.
It ls llkewlse well-known that metlcaments are more effectlve when they are protected from the envlronment of the rumen. See, for example, U.S. Patent Nos. 3,041,243 and 3,697,640.
The coating or fllm forming materlal according to this lnvention provltes protectlon aDt release characterlstlcs, and lnclutes a mlxture or blend of t lea6t one "polymerlc" ~ubstance and at lesst one "hydrophobic"
~ubstance. The polymerlc substance 1B a ~ubstantlally continuous matrlx ~nt accounts for about 25X to about 95% of the welght of the coatlng materlal. Generally, the more acldlc and more soluble cor- ~aterlals requlre greater ratlos of hydrophoblc substance to polymeric sub~tance, 30 whlle more baslc and less ~oluble core materlals require lesser ratlos of hydfophobic ~ubstance to polymerlc substance, within this range. The hydrophobic subs~ance is di~persed ic the polymeric matrix, and accounts 49;

or between about 75~ to about 5% of the weight of the coating material.
The coating material has the ability to withstand environmental conditions of the rumen, and the ability to expose the core material of the pellet in the environment of the abomasum.
Thus, the coating material is resistant to pH conditions of about 5.5 for at least about 24 hours. The coating material releases the core material after exposure to environmental conditions of the abomasum or intestines having a pH of about 3.5 after a time of from about 10 minutes to about 6 hours. The exposure of the core may occur by the coating becoming permeable to the fluids therein or by dissolving or disintegrating. Another requirement for the coating material is to have the ability to withstand storage conditions of relatively high heat and/or humidity without a sig-nificant amount of blocking.
Core materials having a pH of greater than about 5.5 are most useful in this invention. Thus, any core material which is beneficial to the ruminant such as a nutrient or medicament having charactertistics within these parameters may be used. Pre-ferred core materials include amino acids, proteins, various othernutrients, as well as antibiotics and other medicaments.
Thus, in accordance with the present teachings, a pellet is provided which is adapted for oral administration to a ruminant which comprises a core material which has a pH greater than about 5.5, the core material being beneficial to the ruminant postruminally, and a coating surrounding the core material, the coating being resistant to pH conditions of about 5.5 for at least six hours and adapted to release pellet core material after expos-~i4~

ure to a pH of about 3.5 after a time of from about 10 minutesto about six hours. The coating comprises a) a film-forming polymeric material which contains at least one basic amino group~
ing and in which the nitrogen content is from 3 to 14% by weight of the total molecular weight of the polymeric material, the ; polymeric material consists essentially of at least one polymer, copolymer or blend of polymers selected from the group consisting of cellulose propionate morpholinobutyrate, aromatic basic amino-containing polymers, dialkylamino ethyl acrylates and methacrylates in which the alkyl group contains from 1 to 6 carbon atoms, con-densation polyesters and polyamides, and b) a hydrophobic material dispersed in the polymeric material selected from the group con-sisting of waxes, resins, polymers, fatty acids which have from 12 to 32 carbon atoms, aluminum salts of fatty acids having from j 12 to 32 carbon atoms, and polyfunctional carboxylic acids having ,;
a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight of from 400 to 1000, the hydrophobic material being present in an amount between about 5 and about 50% by weight of the polymeric material which the coating making up about 5 to about 50% of the weight of the pellet and having a sticking tem-perature of at least about 50C.

BACKGROUND
U.S. Patent No. 3,619,200 relates to chemically modifying pellets and/or using a surface coating therefor. Pro-teinaceous feed is protected from breakdown within the rumen by the modification of protein itself, by the application of a pro-tective coating to the feedstuff, or by combina~ion of both.

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Various polymers are disclosed in this patent including copolymersof vinylpyridine and styrene. Canadian Patent No. 911,649 discloses treatment of proteinaceous materials with substances which are capable of reacting with proteins to form a polymeric proteinaceous complex on the surface of the material or by reacting the proteinac-eous material with a polymer or copolymer of a basic vinyl or acrylic monomer. This patent also discloses the use of copolymers and terpolymers derived from essentially a basic substituted acry-late or methacrylate monomer ~', ~ ~ -5b-1 ~ ~?~ ~ 96 2nd at l-a~t one ethylenlcally unsaturated co~pound as ru~en ~table coatlngs. U.S. Patcnt No. 3,880,990 ~nd ~riti~h Patent No. 1,346,739 relate to an orally admlnlstratable ru~ln~nt compositi9n wherein a medicinal zubstance 1B cncapsulated or embcdted $n a nor~ally solid, physlologlcally acceptable bsslc pol~mer. The compo~ltlon9 ere produced ~y diapersing a ~etlc~nal sub~tsnce in a flrst ~ol~ent and ~dding thereto secont ~olvent ~hich is mlsc$ble with the flrst colvent but ln uhich the poly~er ~nd metlcinal subgtance are Yubstantially insoluble. There is no ~uggestion of modifying the polymer by the use of attitlves. U.S.
Patent No. 3,041,243 relates to coatings for oral meticaments. These coatings are water-$nsoluble but acit-~oluble fllm-forming polymers. An e~ample mentlonet in thls patent 18 2-methyl-5-vinyl pyrltlne copolymerized w$th v~yl acetat~ acrylonltrile, methyl acrylate or styrene.
U.S. Patent No. 3,697,640 relates to materials such as medlcaments and nutrients for rumlnants whlch are coatet with nltrogen-contalnlng celluloslc materlals such as, for example, cellulose proplonate morpholino-butyrate. Thi~ patent, however, fails to suggest the use of any atditives in the nltrogen-containing cellulosic material, ant U.S. Patent No. 3,988,480 relates to a proteinaceous feed~tuff for rumlnants whlch has been treated 20 with acetlc acld to renter lt rumen stable.
U.S. Patent No. 3,383,283 relates to coating pharmaceutical pellets wlth a plurallty of charges of fatty acit as a melt or in solution.
The fatty aclt ~ay then be tusted with a fine lnert powder such as talc.
~here i5 no ~ugge~tion of using a continuous ~atrix polymer.
U.S. Patent No. 3,275,518 relates to a tablet coating compositlon comprlslng a filmrforming resin or plastlc ant a hard water-~oluble or ~ater-tispersible sub~tance. Stearlc scld is mentionet a8 an optional water-in601uble wax which may be included as an attitive. ~dditional materials such as tyes, pigments, water-insoluble waxes, plasticizing 30 agents, etc., may also be atded to the coat$ng. ~owever, the film-formlng resin or plastlc according to this patent is selectet from the group ccns~8ting of poly(m~thylstyrene), methyl~tyrene-acrylonitr$1e copoly~ers, poly(vinylchlorite)~ poly(vinyl butyral), pentaerythritol or alkyd esters of rosin or tified rosin nt terpene derived ~lkyd resins.
There ls no suggeatlcn of the polymers nccording to applicants' invention.
In fact, the pl~Jtlc or re~in 18 te~cr$bed as water-permeable, nd the coatlng apparentlg is ~ot designed for rumin~nts.
U.S. Patent No. 3,623,997 relates to a ~ethot of ~ealing polymeric material walls of mi~ute capsules bg trestlng the capsules with a waxy msterial. The wax ls introduced ln a solvent whlch i9 ~ubcequently drled and the ~ax $- left a~ a res$due 1~ the walls. The 10 capsule walls ohrink aud lose ~olvent and then entrap the wax tlghtly as a sealing material. There i8 no $ndicatlon, however, that the polymer coating is designed to function for ruminanta, and the wax is used as a ~ealing material. ~pplicant's hydrophobic substance is dispersed in the polymer.
U.S. Patent No. 3,073,748 relates to tablets coated with a solutlon of an a~photeric film-forming polymer. The polymer ls tescribed as one selected from the group cQnsl~ting of copolymers of (a) vinyl-pyrldines wlth (b) a lower allphatic o~B-un~aturated monocarboxylic acld of 3 to 4 carbon atoms and copolymers of (a), (b) and a neutral co-20 monomer selected from the group consisting of methyl acrylate, acrylonitrile,vinyl acetate, methyl methacrylate and styrene. There ls no suggestion of uslng a dispersed atditive.
Brltlsh Patent No. 1,217,365 and Canadlan counterpart No. 851,128 relate to a particulate feed tdltlve composltion for ruminants whereln each partlcle comprlses one or more d o aclds totally encased in a contlnuous fllm of protective material which is transportable through the rumen without substantlal degradatlon therein but which releases the actlve substance posterior to the omasum when the par~iclfs have a density within the range of 0.8 to 2.0 and diameters in the range of 200 30 to 2,000 mlcrons. Suggested as protectlve materials are fatty acid trlglycerldes ~uch as hydrogenated vegetable ant animal fats, waxes such as rlce-bran wax, a~d resin wax bl _ds which are e~ulsified and/or . .

tlssolved in the intes~inal tract.
PELLETS
The pellets according to this invention are adapted for oral adml~istratlon to a = inant. The pellets are of a suitable ~ize, such s between about 0.05 in. acd 0.75 ln. ln diameter. Also, the pellets must be of suit~ble density, i.e., a specific gravity of between about 1 ant 1.4, have acceptable odor, taste, feel, etc. The pellets include a core and a continuous, fllm or coating completely encapsulating the core. The ~hape ls usually not critlcal, except the pellets are commonly spherical for ease in coating.
CORE MATERIAL
The core is of a material beneficial to the ruminant upon reaching the abomasu~ or intestine. ~ormally, the core is a solid material which has been formed lnto particles, such as by pelletizing.
The cores may then be rounded if desired, by conventional means, such as by tumbling. The core should have sufficient body or consistency to remain intact turing handling, particularly during the coating operation.
Suitable core materials include various medicaments and nutrients such as, for example, antibiotics, relaxants, drugs, anti-parasites, amino 20 acids, proteins, sugars, carbohydrates, etc. The core may also contain inert filler material such as clav.
The ability of the coating to protect the core is related to the pH and water solubility of the core. The cores to which the present invention is applicable are those having a pH of greater than about 5.5.
Some amino acids suitable for use as a core material, their pH
and solubility are as follows:
Amino Acids Solubility and pH of Saturated Solutlons Solubility R./100 ~. water at 25C. pH

DL - Alanine 16.7 6.2 L - Arginine 21.6 11.8 DL - Methionine 4.0 5.7 L(-) - Tyrosine 0.05 7.3 Proteins from various sources are also valuable for practice or the invent$on. Generally, proteins are polymers derived from various combinations of amino acids. Proteins are amphoteric substances which are soluble or dispersable ~ aqueous ~edia eith~r more acidic or more basic than the partlcular protein being considered.
The core material may be made ready for coating by the following method. The nutrient, medicament, or the like, is mixed with water, binder and sometimes fillers and/or inert inorganic substances added to ad~ust the specific gravity of the pellet and the resulting plastic dough-like mass is extruded or rolled to obtain suitable size particles.
Adhesive binders are added to strengthen the pellet and can be nontoxic vegetable gums, starches, cellulose derivatives, animal gums and other similar substances well-known in the art of food thickening and tablet making. Inorganic additives used to adjust the specific gravity of the pellet include such substances as insoluble, nontoxic pigment-like materials such as metal sulfates, oxides and carbonates having a relatively high tensity. The final desirable range of specific gravity for the rumen protected pellets is from 1.0 to 1.4. Af~er creating suitable size pellets by extrusion, rollin~ or other suitable means, the pellets 20 are dried to remove the water. The pellets are then coated by contacting them with a solution of the protective coating material in a suitable solvent or mixtures of solvents as hereinafter described. Typical solvents of value include lower alcohols, ketones, esters, hydrocarbons, and chlorinated hydrocarbons.
COATING
The coating material is capable of forming a continuous film around the core by the evaporation of solvent from the coating material.
It has the ability to withstand environmental conditions of the rumen, and the ability to expose the core material of the ?ellet in the envir~nment 30 of the abomasum. Thus, the coating material should be resistant to pH
conditions of greater than about 5 for from about 6 to about 30 hours The coating material should release the core material after exposure to _ g _ abomasum envlronmental conditions having a p~ of about 2 to about 3.3.
Release should occ~r within the residence time in the abomasum or later in the intestinal tract but at }east wiehin a time period of 6 hours after contacting pH 3.5 or less. The exposure of the core may occur by the coating becoming permeable to the contents of the rumen, such as by dissolving, disintegrating, or extensive swelling. The coating material ~8 physiologically acceptable, l.e., the coating material should not lnterfere with the ruminants' healthy or normal body functioning.
Another requirement for the coating material is its ability to 10 withstand Ytorage conditions of relatively high heat and/or humidity without a significant amount of blocking. It should have a sticking temperature of greater than about 50C. Sticking temperature is defined as the tempe~ature at which adhesion sufficient to cause rupture of the coating upon forceable separation between coated particles occurs when an applied force of 0.25 Kg/cm2 holds the particles in contact for 24 hours. Also, the coating materlal is preferably soluble or dispersable in organic solvents having boiling points of between about 40C. and 140C. to permit conventional coating processes such as spray coating to - be used. Particularly suitable solvents include methylene chloride, 20 chloroform, ethanol, methanol, ethyl acetate, acetone, toluene, isopropanol or mixtures of these.
The coating or film forming material according to this invention includes a mixture or blend of at least one "polymeric" substance and at least one "hydrophobic" substance. The polymeric substance is a con-tinuous matrix ant accounts for about 23 to about 95", of the coating weight.
Generally, the more acidic and more soluble core materials require greater ratios of hydrophobic substance to polymeric substance, while more basic and less soluble core materials require lesser ratios of hytrophobic substance to polymeric substance within this range. The 30 hydrophobic substance is normally dispersed in the polymeric matrix, and is present in a~ounts of between about 5 and 5~, based on the weight of the polymeric material.

Inert filler materials such as clay, bentonite, limestone, etc., may also be used in cuitable amounts.
PO~YMER
The polymer~c aubstances which are useful in the coatings of thls invention lnclude those, ~hich, in combinatlon with the hytrophobic substance described hereinafter, are physiologically acceptable and resistant to a pH of greater than about 5 but capable of releasing the core of the pellets at a pH of less than about 3.5, at the normal body temperature of ruminants (37C.). The polymeric substances include polymers, copolymers and mixtures of polymers and/or copolymers having basic am~no groups in which the nitrogen content of the polymeric sub-stance is between about 2 and about 14% andtypical molecular weights between about 5,000 and 300,000. The basic amino groups may be of the aliphatic type in which case they will contain from about 2% to about 10% by weight of nitrogen in the basic amino groups. The basic amino groups may also be of the aromatic type in which the basic amino groups are attached directly to the aromatic ring, or are part of the aromatic ring structure in which case they will contain from about 6% to about 14~
nitrogen in the basic amino groups. The polymeric substances are macro-20 molecules of sufficient molecular weight to have film-forming properties when the polymer is deposited from a solution and after removal of a solvent, dispersing medium or on cooling from a melt.
Polymeric substances having the characteristics defined herein include certain modiflet natural polymers, homo- and interpolymers obtalned by additlon polymerization methods, homo- and copolymers obtained by condensation polymerization methods and mixtures thereof. The polymeric material is comprised of at least one polymer, copolymer, or blend of polymers selected from the group consisting of cellulose derivatives such as cellulose propiona~e morpholinobutyrate; containing addition-30 type monomeric moieties such as acrylonitrile; vinylated derivatives ofpyridine; styrene; methylstyrene; vinyl toluene; esters and amides of me~hacrylic acid; esters and amides of acrylic acid; polymerizable - , ethylenically unsaturated aliphatlc hydrocarbon monomers such as ethylene, propylene or butadiene; vinyl esters such as vinyl acetate, vinyl propionate or vlnyl stearate; vinyl ethers such as ~ethyl, ethyl, propyl or stearyl, vinyl substituted heterocyclic ring or condensed rlng compounds containing ; bas$c nitrogen configurations such as vlnyl carbazole, vinyl quinoline, N-vinylpyrrole and 5-vinyl pyrozoline; containing condensation-type pol~ners wherein a tiacid such as phthalic, tereph~ahlic, and succinic are combined with polyfunctional alcohols to form polyesters wherein elther the acld or glycol moiety may contaln basic nitrogen not reactive in the polymerization process but reactive to variable pH enviro~nents and wherein the same or similar diaclds may be reacted with polyfunctlonal smlnes to form polyamlde-type polymers containlng basic nitrogen not reacted in the polymerization process; and other basic nitrogen containing polymers such as preformed polymers which have been for~ed by reacting an existlng polymer with a nitrogen containing organic or inorganic j moiety such as polybutadiene to which ammonia has been reacted with the remainlng double bond. Especially preferred are poly(vinylpyridine), polymeric derivatlves of vinylpyridine, and the copolymers of the various isomers and derivatlves of vinylpyrldlne copolymerized with one or more of the above-mentioned addition type nomers.
Also, especially preferred are copolymers of 2-methyl~5-vinylpyridine and styrene, and in particular, the copolymer of about 75-80% by weigh~ 2-methyl-5-vinylpyrldine and about 15-25~ by weight styrene, as well as the copoly~ner of 55-65% by weight 2-methyl-5-vinyl-pyridine and about 35-45% by weight acrylonitrile. These copolymers are commercially available or may be produced by conventional techniques well known in the art.
HYDROPHOBIC SUBSTANCE
Hydrophob$c aubstanc~s whlch are physiologicallv acceptable 30 and have the correct degree of co~patability with the polvmer are co~nercially available. It is important that the pol~ner and hydrophobic substance have a tegree of co~patab$1~ty to permit the fil~ to remain in~act in .

-the rum~n environment, but to permit permeation of the ab~masal fluid tothe core while the pellet ls in the abomasum.
While ~e do not wish to rely or. any particular theory as to why the coatings containing the hydrophobic substance are better protective, we believe the f~nct~on is generally that the overall ~usceptibility of the matrix films to aqueous weakly acidic envlronments ls retuced.
Further, we believe that in view of ~he inherent polar naeure of polymers contalning enough basic nitrogen groups to be functional wlth respect to the dlfferences of rumen and abomosum pH that 8 reduction in water ~u~ceptibility of the fllm is required, e~pecially when the çore materlal is acltic and/or very water soluble. While the general theory believet to be true ls as descrlbed above, there are subtle varlatlons in the precise mode by which the hytrophobic substance is functional. A class of hytrophibic substances of value are fatty acits containing from 10 to 32 carbon atoms such as lauric, oleic, stearlc, palmitic and linoleic.
These substances are well known to be water insoluble tue to the long hydrocarbon radical but to react to water tue to the polar nature of the carboxyl group. In the seleceed ba~lc amlno group-containing polymers, the carboxyl group of the fatty acid is able to react with the basic nitrogen group to form a weak salt-type linkage. This attachment to the polymer serves to csuse the fatty acit to be fixed in the polymer matrix.
The hydrophoblc hytrocarbon chain of the fatty acid tends to render the matrix water resistant and thereby tecreases ~welling of the otherwise water suseptible polar fllm. Both the lnterior of the matrix film and the surface is now water resistant in aqueous environments at pH above sbout 5Ø However, at pH values below pH 4.5 and especially below about p~ 3.5 the affinity of the basic nitrogen group for water and the hydrogen lon overcomes the increased water resistance. The film reacts with the acid environ~ent ~nd loses barrier properties sufficient to allow the core ~aterial to escape to the environment.
Polyfunctional carboxylic acids may be derived from natural products or obtained by organic synthesis but the ratio of carboxyl -group to hydrophobic organic radical should be at least 1 to 10 based on the molec~lar weight of the organic radicals. Also included in this class of synthesized organic hydrop~-lobic acids are mono and poly-functional acids containing silicone or flourinated carbon groups located at least 4 atoms distant along the m~lecular c~ain fram the position of the carboxyl group or groups. Also, included in the class of hydrophobic substances are the nontoxic multivalent metallic salts of the above acids such as the stearates, oleates, fatty acid dimerates, and palmitates of aluminum and iron and the calcium, magnesium and zinc salts of the higher molecular weight crystalline analogs of the above acids. When the cation is trivalent as for aluminum and ferric iron, the m~lar ratio of orga~ic acid to metal ion is 2 to 1 or 3 to 1 and the acid can be any monofunctional organic acid having one carboxyl group and at least 10 carbon atcms in the organic radical attached to the carboxyl group.
When the metal ion is divalent such as ferrous iron, calcium, magnesium or zinc the organic acid may be monocarboxylic or polycarboxylic and the ratio of metal ion to non-carboxylic carbon atoms is at least 1 to 26.
Natural and synthetic waxes and resins added at levels depending on the degree of hydrophobicity and ccmpatibility in the matrix film are of value in the practice of the invention. Waxes and resins are useful that have a molecular weight of from S00 to 2000 and a critical surface tension of less than 31 dynes/cm as determined by the Zisman method described in "Contact Angle Wettability and Adhesion". Advances in Chemistry Series #43; Edited by Robert F. Gould; published by the American Chemical Society; 1963; Chapter l; and have a solubility in the matrix film of less than 5~. mese waxes and resins are dispersed in the film in at least amounts equal to 2 times the solubility and up to 30% of the total weight of the matrix polymer. Typical waxes and resins include beeswax, petroleum wax, damar, hard manila, phenolic resins, rosin and maleated low molecular weight polyhydrocarbons. Also included in the hydrophobic substances are polymers having molecular weights of frcm 2000 to lO,000, a critical surface tension of less than 31 dynes/cm measured by methods in the reference to Zicman described above. Useful 'L~(~4496 polymers have a solubility or compatibiiity in the matrix film of lessthan 5% on a weight basis and are present in the film at levels at least eqlal to two times the solubility and up to 30 weight percent of the matrix film. Of particular value are the polymers and copolymers containing silicone groups in the main polymer chain or in a side chain and polymers and copolymers containing flourinated carbon groups in a side chain.
Regardless of the exact nature of the hydrophobic substance it must be soluble or colloidally dispersible in the coating solvent when one is used. m e hydrophobic substance makes up from 1 to about 50% of the combined weight of polymeric material and hydr~phobic substance.
Suitable hydrop~obic substan oes also include fatty acids having from 12 to 22 carbon atoms, such as oleic acid and stearic acid, dimer acids, trimer acids, aluminum salts of fatty acids, waxes, resins, and certain polymers such as polymers containing very hydrophobic chemical groups such as silicone moieties and certain multivalent cation soaps.
The hydrophobic substance may be amorphous or crystalline and preferably essentially dispersible in the coating solvent when a solvent is used in which case it should not contribute significantly to the solution viscosity.
Aluminum salts of such acids, for example, aluminum oleates, aluminum stearates, aluminum dimerates, are also useful. Also, the hydrophobic material may be one or mDre Folycarboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight greater than 300, preferably about 400 to about 1000, are useful.
Blends of these acids and/or salts are also useful.
We believe the function of the hydrophobic substance as a dispersed phase in the protective polymer layer:
a. reduces wetting of the ooating and therefore initial attack by water, b. reduces total volume of coating affected by water, and c. extends the length of permeable pathway the water must travel to core.

APPLICATICN OF Ca~ING
In the practice of this invention, the Folymeric material may conveniently be dissolved in a suitable organic solvent which would be physiologically acceptable in the event there are residues upon evaForation of the solvent, as hereinbefore described. The hydrophobic substance is blended in the solution, wherein the polymeric substance is a oontinuous matrix and the additives are dispersed therein. The coating solution may be applied by various well kr~wn means such as, for example, brushing, dipping, spraying, fluidized bed, etc.
A preferred apparatus and process for ooating the cores will ncw be described.
In the drawings:
Fig. 1 is an elevation view in cross-section illustrating the app æ atus and showing the gas flows and p æ ticle flcw path fro~ the annular bed to and through the truncated hollow cone and in return to the annular bed;
Fig. 2 is a partial elevation view in cross-section of a m~dified app æatus and illustrating the addition of an annul æ airfoil and showing the flow of gases relative to the aerodynamic structure and annul æ airfoil;
Fig. 3 is a p ætial elevation view in cross-section of another mDdified apparatus similar in all other respects to the modification shown in Fig. 2 except that the cross-section of the app æatus below the coating chamber is of the same diameter as that of the coating chamber;
Fig. 4 is a partial elevation view in cross-section of the upper portion of the app æ atus of the invention for illustrating one possible manner of oollecting the finally ooated particles by use of an air porous bag; and Fig. 5 is a graphic illustration of the height, thickness and angul æ relationships of the annular airfoil with respect to the aero-dynamic structure, and the height abo~e (ha) and height below (hb) relationships of the aerodynamic structure to the greatest cross-sectional diameter of the aerodynamic structure.

iLl~
The apparatus employs a truncated hollaw cane in which theslope or pitch of the walls is such that the particles are accelerated at an increasing rate and not just at a rate so as to maintain the gas velocity at any given point in the cone at a level greater than that necessary to move the particles in a continuous upward direction. The slope or pitch of the walls would therefore appear to be more pronounced than the slope or pitch of the cone embodiment disclosed in the Larson et al patent. The significance of the slope or pitch of the truncated hollow cone of the invention is that when a particle first enters the cone at one rate of speed, it is then accelerated to a different rate of speed and continues to be accelerated to still different rates of speed as it moves upwardly thr~ugh the cone. In this manner a separation is brought about between the particles so that after they are caated they may become sufficiently dry before caming into oontact with other particles and thereby avoid undesirable clumping or agglamerating together. The pitch of slope is such as to cause a compression of the gas molecules and thereby cause the acceleration at an increasing rate.
In reference to Fig. 1, the o~ating apparatus is designated in general at 10 and includes a vertically disposed first hollow o~lumn 12 of regular shape. By "regular shape" is meant that it may be cylindrical, octagonal, hexagonal or of other configuations, so long as the hollow oolumn is generally symmetrical with respect to its oentral axis. The hollow column contains therewithin the particle storage, coating, drying and deceleration zcnes, which will be described herein.
A truncated hollow cone 14, which may also be a tapered octagon or other tapered polygonal oonfiguration, in other words, generally c~ne-shaped configurations, serving as an enclosure in which the upwardly flowing gases are received, compressed and acoe lerated, is centrally disposed within the first hollow column, has a uniformly decreasing cross-section in the upward direction and is of predetermined height dependent upon the size and weight of the particle to be treated.
Within the truncated hollaw cone in ascending order are the coating and ~1~449~; .
drying zones. The cone serves also to separate the coating and dryingzones from the deceleration zone, which lies in the region akove the upper end of the cone, and from the storage zone, which lies therebetween the o~ne and the interior wall surface of the first hollow column.
The first hollow column 12 is provided at its lower end with an inwardly tapered base 16. The lower end of the truncated hollow cone is spaced radially inwardly from the inwardly tapered base.
A second vertically disposed hollow column 18 of regular shape is connected to the inwardly tapered base of the lower end of the first hollow oolumn, the wall surface of the inwardly tapered base forms a juncture with the wall surface of the second hollow column.
Disposed within the second hollow oolumn is a first plenum chamber 20 into which a suitable ccmpressed gas, such as air, may be provided through tw~ or more opposed inlets 22, 24; a gas or air colli-mating plate 26; a second plenum chamber 28 separated from the first plen~lm chamber 20 by the collimating plate 26; at least one gas shaping or aerodynamic structure 30 disposed within the second plenum chamber; and a particle support or supporting screen 32, which extends across the second hollow column and is located above the aerodynamic structure.
The gas or air collimating plate 26 is a perforated plate which causes the gas or air in the first plenum chamber to pass into the seoond plenum chamber in an essentially vertical and uniform flow, as illustrated by the vertical arrows.
The gas shaping or aerodynamic structure 30 in ocoperation with the adjacent wall surface of the second hollow column, compresses and focuses the upwardly moving gas or air flow so that it flows over a portion of the surface of the aerodynamic structure, upwardly through the particle support screen and into the entrance end of the truncated hollow cone. The flow upwardly around the aerodynamic structure constitutes an annular flow, which adheres to the surface of the aerodynamic structure in the nature of a Coanda flow.

.~ .

A spray Dozzle 34 preferably extends above the top of the aerodynamic structure 30 through which $s sprayed a suitable coating material. It i6 re co~venlent to have the spray nozzle located at the top of the centrally dispo~ed aerodynamic structure. The coating material i8 supplied from a sultable source (not shown) through a conduit 36 extending up through the aerodynamic structure, and an atomizing gas may be suppliet from a suitable source (not shown) through a conduit 38, also extending up through the aerodynamic structure, for subsequent mi~ing at the nozzle. The spray nozzle may also be pressure-operatet rather than gas-operated.
The upper ~urface of the gas shap~ng or aerodynamic structure is centrally disposed within and extents generally horizontally across the cross-section of the vertically disposed hollow column. In other words, it has a cross-4ectional plane generally perpendicular to the vertical axis of the vertically disposed hollow columns. The outer edge of the upper surface is equally spaced from the wall surface of the hollow column and defines therebetween with the wall surface of the hollow column a reduced pressure region for acceleration in velocity of the upwardly flowing gsses in such manner that the upwardly flowing gases form a boundary layer that is directed away from the wall surface of the hollow column and that atheres to the upper surface of the gas shaping or aerodynamic structure for flow across a portlon thereof.
The upper surface of the aerodynamic structure may be flat (not illustrated), but i8 preferably curved or approximately spherical as illustrated. It may have a helght (ha) above the cross-sectional plane (See Fig. 5), therefore, of from about 0% to about 150%, or preferably from about 10% to about 150~ of the greatest cross-sectlonal ~lameter (D) (See Fig. 5) of the aerodynamic structure.
The surface below the greatest cross-sectional diameter may 30 also be flat (not illustrated) and may therefore have a depth or height (hb) below of from about 0% to about 200~ of the greatest cross-sectional diameter ~D) (See Fig. 5). Preferably, the surface below is formed in the manner disclosed in the drawlngs.

9~;

The aerodyna~ic structure as disclosed and as described is thus adapted to compress and ac oelerate the flowing gases near the periphery of the l~ollow column and direct them toward the oenter of the hollow column at an angle from about 10 to about 45 from a direction parallel to the flowing gases from the gas or air plenums.
me truncated hollow cone defines at its lower end a large diameter somewhat smaller than the diameter of the vertically disposed first hollow colu~,n, and has an increased diameter from about 0% to about 25% greater than that of the plane of the particle support screen.
The lower end of the truncated hollow cone is spaced a predetermined amount from the screen and the upper end defines a diameter of from about 20% to about 80% of that of the lower end. The height of the cone ranges from about one to about six times the diameter of the lower end.
In operation, particles 40 may be suitably loaded into the coating apparatus 10, as through a closable opening at 42, into the storage zone lying between the wall surface of the first hollow column 12 and the outside wall surface of the truncated hollow cone 14. me particles are thus situated in an annular bed around the truncated hollcw cone 14. The sloping outer wall surfaoe of the truncated hollow o~ne, the inwardly sloping tapered base 16 of the first hollow column and the screen 32 serve to contain the particles in the annular bed prior to starting-up the coating operation.
The gas or air is turned on to start the circulation of the paxticles or pellets frcm the annular bed or storage zone into the coating, drying and de oe leration zones and in return ~o the upper portion of the annular bed. The atomizing spray is then turned on and appro-priately adjusted in a suitable manner by oontrols (not shown).
As previously pointed out, the Coanda flow or effect is named for the tendency of a fluid, either gaseous or liquid, to cling to a surface that is near an orifice from which the fluid emerges. Such "orifice" in this instance is formed in the region therebetween the closest approach of the aerodynamic structure to the adjacent side wall r, ~

Aurface. The gas flow emerging from the "orlfice" region around the aerodyn3mlc atructure ls an ~nnulsr flow whlch cllngs or adher~s to the surface of the aerodynamic structure. The flow, therefore, from any one ~elected locatlon around the "orifice" is opposed by the other flows so that lt i~ prevented from continuing further over the upper ~urface of the aerodynamlc structure by being forced upwardly away fro~ the upper ~urface at some polnt for flow into the truncated hollow cone. A
p-rtial vacuum ls formed in the region ~ust above the upper surface of the aerodynamic structure and at the lower edge of the truncated hollow cone and this alds ~n the compression and focusing of the rislng annular flow of gases. The upward flow is consequently caused to have a conical shape, as seen in phantom lines in Fig. 1 at 44 within the cone, ant has a centering effect on the particle impelled upwardly through the cone.
As also pointed out, an important part of the Coanda effect is the tendency of the flow or gas or liquid to entrain, or draw in, more gas or liquid from the surrounding environment. In this latter manner, the particles are pulled from the annular bed or storage zone into the upwsrdly flowing gas due to the aforementioned partial vacuum or reduced pressure regioD that exists ~ust abo~e the screen adjacent the path of upward flow as a consequence of this Coanta effect. This reduced pressure or partial vacuum is directed perpendicular to the annular airflow from the "orifice". It is a different effect, however, from the horizontal shunting action occurring in the Wurster et al apparatus because there the horizontal shunting woult extend not only toward the axis of the apparatus but al80 inefficiently toward the outer wall ~urface of the coating apparatus.
Once the particles are pulled into the upwardly flowing gas within the truncated hollow cone, they are impelled upwardly in an accelerating gas or air stream. As the particles pass through the lower central reglon or coating zone within the cone, they are contacted with an atomlzed spray coating of material. This atomized spray emerges from the spra~ nozzle 34 because the liquid coating substance is either .

forced through a single orifice designed to convert bulk liquids into droplets, or the liquid and an atomizlng air strea~ emerge ci~ultaneously from ~ets ad~acent to each other. In either case, the fine droplets of coating material are in a flawable atate, because the material i9 dissolved or melted in the regioc immediately above the spray nozzle.
Further up the truncated hollow cone, the liquid nature of the coating material, as teposited on the pellets or particles, changes to ~olid by evaporative or other solldification processes. Durlng the trsnsition from liquid to solid, the coated particles pass through a 10 stage when they are Rticky or tacky a~d would agglomerate if they contacted each other. This contact i5 prevented by the slope or pitch of the walls of the truncated hollow cone and consequent accelerating boost of the particles to separate them in the manner previously discussed.
The conical nature of the cone causes a compression and accelera-tion of the rising column of gases and the upward velocity or accelera-tion of the partlcles occurs at an increasing rate as they rise ln the cone. This acceleration causes an increasing vertical ~eparation in space between the particles and therefore retuces the tendency for the particles to contact each other until the coating has become nontacky.
20 It is this region of the cone that is thus called the "drying zone".
Whe~ the compressed gases and entrained particles pass upwardly out of the upper end of the cone, they expand into the larger area of the upper portion of the first hollow column and thus decelerate to a velocity too low to suspend the particles. This is the deceleration zone, where further drying takes place, and the particles then fall by gravlty action ~o the annular bed where they gradually move down, also due to gravity, until they are pulled into the coating zone agaln. Thls recycling or recirculation continues until, based on previous experiments, a sufficient coating has been spplied.
The ~tomlzed spray ls turned off, and the gas or alr entraining flow ~ay be shut town or may ~e ~ncreased to drive the coated particles into the uppermost re~ion of the first hollow column, as for collection 4~

in the anner lllustrated ln Flg. 4. Any other sultable manner of unloading the finally coated particles may also be used.
A coating apparatus having the design characteristics essentially as ~hown in Fig. 1, and havlng a dla~eter of eight (8) inches across the lower end and four (4) lnches across the upper end of the truncated hol-low cone, i8 charged with twenty-five (25) pounds of generally ~pherical pellets of animal feed supplement. The pellets are composed of 90X
~ethlonine snd lOZ binders. The average dlameter of the spherlcal pellets 1~ about 3 ~illimeter. About 250 standart cublc feet per minute of air 10 at about 7 p. 6 . i. g. 18 admitted to the plenum chamber 20. This air causes a clrculation of pellets through the truncated hollow cone 14, and the helght of the cone above the support 6creen 32 is ad~usted to obtain a pellet flow rate such that all the pellets in the annular storage zone move through the coDe about once every minute. A coating solution ls pumped through the spray nozzle 34 at the ~ame time as 5 SCFM of atomizing air at 40 p.s.i.g. is supplied to the nozzle. The pumping rate 19 ad~ustet to pump one (l) pound of solutlon per minute. The apparatus ls operated for about 45 minutes. The product ls a pellet core coated wlth about a 2-mil layer of the poly~er.
If the gases flowing upwardly around the aerodynamic structure could be seen as a serles of layers of molecules, merely for sake of di~cussion, lt ls thought that there ls an insignificant flow of molecules or layer or ~o of molecules along the interior wall surface of the Decond hollow column. By "insignificant" i6 meant that such layer or layers of ~olecules will not perform any supporting function of the particles in the annular bed.
Moving, therefore, ratlally inwardly fro~ the lnterlor wall ~urface of the second hollow, the ~ore slgniflcant layers of ~olecules are caused to bend toward the gss shaping or aerodynamic gtructure, the 30 inner~ost adhering to the surface of that structure as they pass upwartly through the "orifice" region. This adherence of the ~olecules to the surface of the aerodynami~ ~tructure ~ay be favorably c~mpared to the 49~

"teapot effect", which is a low-~peed for~ of the "Coanda cffect". When water ls poured ~lowly from a glass, lt tents to ~tlck to the side of the glass in the sa~e ~ay that tea aticks to the spout of a teapot.
~lgh speed fluids behave ~imllarly and adhere to a surface of sultable shape.
As the rislng molecules flow over the surface of the aerodynamlc structure after having passed the "oriflce" region, previously mentioned, at some polnt slong the upper surface of the aerodynamic ~tructure the opposing character of the annular flow forces the molecules upwardly 10 ~way from the upper curface as well as the ad~acent molecule layers. A
partial vacuum ls created above the aerodynamic structure due to the high speed upward flow of gases, causing an inward bending of the upwardly mov~ng molecule~.
In the apparatus herein tescribed, the particles move down in the annular bed by gravity without any "dancing" occurring, and are drawn into the upwardly flowing gases by the partlal vacuum. Thus, anv attrltlon that mlght occur ls greatly minimized, and the overall opera-tion is much more efficient.
In reference to Fi~. 2 in which a motification is disclosed, the 20 same reference numbers will be used to identify similar elements previously described, except that they will be primed to show that it is a different embodiment under tiscussion.
Fig. 2 repsesents an cmbodiment wherein the size of the coatlng apparatus 10' has been increased in order to handle larger batch loads of particles for coating treatment. It has been found that lt is more practical to add an addltional gas shaping or aerodynamic structure or an annular alrfoll 50 instead of increasing the size of the aerotynamic structure 30'. In this manner, larger amounts of upwardly flowing gas or ~1r may be 3upplied undiminished or unobstructed by a larger aero-30 dynamic structure, and the annular airfoll serves to supplement the com-pression and focusing action on the upuard gas flows so that substantially all gas flows ~ove through the truncated hollo~ cone 14'.

4~

Attitlonal or multiple gas shaping or annular airfoils (not 3hown) also ~Ry be u~ed for stlll larger coating apparatus. The exact ehape aDd place~ent of the airfolls are functions of a number of variables.
The ~08t significant of the variables are 6ize of the apparatus, size of the particle to be coated, tensity of the particle, rate of gas or air flow and the rate of recirculation of the particles through the coating zone tesired.
In a larger-scale coating apparatus, therefore, one or more nnularly shaped and pla~ed ~as shaping or aerodynamic structures or airfoils, engled or curved, may be provided concentric with and radially outwardly of the central gas shaping or aerodynamic structure. The annular airfoils may be attached to the central aerodynamic structure or to the walls of the coating apparatus by radial struts in such manner as to exert a minlmum deflection of the upwardly flowing gases.
The annular aerodynamic structure is inwardly inclined in the upward direction so that lts lnclinatlon lles in a plane extending about 10 to about 45, as measured from the axis perpendicular to the diameter of the coating apparatus. The inwardly inclined annular structure provites a surface on which the gas or air impinges for subsequent shaplng ant dlrectlon upwardly into the truncated hollow cone.
The vertical height of the annular structure may be about 10-50% of the perpenticular cross section tlameter of the coating apparatus.
In reference to Fig. 5, when the annular gas shaping structure has the configuration of an airfoil having at least one curved surface cxtending generally in the direction of gas flow, the overall angle of a line described from a point Pl- on the lower rim of the airfoll to a point, P2, on the upper rim ln the vertical tlrection, or perpendicular to a line whlch is tangent to the upper curved surface of the centrally 30 tisposed aerodyna~ic structure, is from about 10 to about 45 inward faclng, a~ ~essured fron the aYls perpendicular to the tiameter of the coat~ng ~pparatus.

The cross-~ectlonal configuration of an annular alrfoil ln a plane described from the center of the cross-sectlonal area of the coating apparatus to ~ point, Pl, on the lower rim of the a~rfoil to a point, P2, in the upper rlm of the alrfoil 19 teardrop, or simllar to the cross-sectional shape of a llfting aerodynamlc shape, and having the thicker cross ~ection on the forward part wlth reference to the dlrection facing the upwardly flowing gases. The thickest part i6 located about two-fifths (2/5) to about one-half (1/2) of the height in the vertical dlrection. In other words, the helght (H) of the thlckest part (T), lO or ~T is equal to about 2/5 a to about 1/2 H. The thickest cross section (T) is from about one-si~th (1/6) to about two-fifths (2/5) of the helght (~) of the alrfoll; or T ls equal to about 1/6 H to about 2/5 H.
The size, placement and geometrical configuration of the annulsr gas shaping structure are such, therefore, that the upwardly flowing gases are teflected radlally inwardly st an angle from about 10 to about 45 from a dlrectlon parallel to the original gas flow.
In reference to Flg. 3, the same reference numbers wlll be used to itentify similar elements prevlously descrlbed, except that they 20 wlll be double-primed to show thRt it ls stlll another dlfferent embodi-ment under dlscussion.
Flg. 3 represents an embodiment wherein the size of the coating apparatus 10" has been iucreased to the same extent as that disclosed in the Fig. 2 embodiment. The ombodiment in Flg. 3 differs from the embodiment in Fig. 2 ln that the flrst and second hollow col = s are disclosed as being co-extensive ln cross-sect1Onal diameter. In other words, the coating apparatus ls disposed wlthin a slngle hollow column.
It could also be of smaller size so that only one gas chaplng or aero-dynamlc structure 30'' is employed as in Flg. 1, lnstead of a size 30 requiring the anoular ~lrfoil 50".
The recycling or reclrculatlon in this embotiment is necessarily faster because the partlcles are ~ot aR readily restrained in the annular bed region as they would be if there were an inwardly tapered base to assist in such restraint. Proportionately ~naller batch loads may be used, therefore, ~ince the recirculation of the particles i8 substantially continuous with the particles spe~d~ng very llttle time in the annular bed. For this rea~on, an e~botiment of this character 18 sui~able for special purposes, ~ile the embotiments of Fig. 1 and Fig. 2 are deemed to be of more general use.
ID Fig. 4, this embotiment represents one manner of unloating a coating apparatus, ant was brlefly mentloned above with respect to one possible operatlon of the embotiment of Fig. 1.
Only the upper portlon of a coating apparatus 60 is shown, and it could be used for any of the previously described embotiments. A
conduit 62 is installed within the upper portion of the apparatus, as shown, and a gas or air porous collectlon bag 64 may be installed at the remote end of the condult for collecting the finally coated particles in the manner already heretofore tescrlbet.
In any of the embodiments descrlbed above, the truncated hollow cones may be atapted to be ad~usted for movement upwardly or downwardly in a vertical plane. The same may also be accomplished with the aero-dynamic structure, the annular airfoils and the spray nozzles, as desiredto suit gas or air flows, particle sizes and weights, coating material consistencies ant whatever other controlling factors may be concerned~
The particles or pellets to be coated may be batch-loaded and treated; or, if deemed advantageous, two or more such coating apparatus may be arran8ed in cascaded manner to provide for a continuous coating operation. The inlet for the partlcles in a cascaded arrangement may be diposed above the annular storage of one apparatus and the particles ~etered in predetermined manner into the annular storage bed, while the outlet to the next coating apparatus may be tisposed on the opposlte 30 sicle of the annular storage bed and constitute a weir for outflow of exce~s coated partlcles. The inlet may also be disposed for gravity flow of particleQ to or intD the annular storage bed. It may be desir-4~

able to provide ~or different coatlngs in different spparatus, or provide supplemental coatin8S-Multiple ~pray ~ozzles may also be e~ployed, as de3ired, toachieve dlfferent coatlng effects.
The examples which follow are submitted for a better understanding of the invention. While the esamples are based on ln vitro tests, the _ vitro experiments shown in the examples s~mulate condltions existing ln ruminants thereby permittlng the study of coated pellets without the use of live animals. It has been determinet by actual in vivo tests that the te0ting of pellets in the aqueous media uset in the examples, slmulatlng the envlro~ental conditions of the = en and abo~asum wlth respect to temperature, pH, etc., provide rellable data concernlng the protection offered by ehe costings in the = en, and releasability of the coatings in the abomasum. Nutrlents such as amino aclds and proteins which may be w ed in the core material are ~nown to be beneficial to ruminants when posltloned in the intestinal tract downstream from the = en.
EXAMPLE 1 (Control) .
600 Gram3 of fi~ely dlvlded lyslne monohydrochlorlde, 60 g. of microcrystalline cellulose having a partlcle slze of about 250 mesh, and 6 g. of gum arabic are dry ~ixed to obtain an essentially homogeneous mixture. 195 Grams of water 18 mixet wlth the powderet m~xture until a homogeneous plastic dough-like con~istency is obtained. This plastic tough ls extruded snd cut to obtain cylindrical pellets havlng a tiameter of about 3/32 in. and 3l32 in. hlgh. These pellets are rounted by tumbling in a rotating d = for 5 minutes and are then drled st 60C.
The dry pellets are ~leved to obtain about 85% yield of pellets ln the runge of 8 to 12 mesh. The pellets are pa~sed through a ~pray zone con-taining atomized droplets of poly~er di~solved in a volatile solvent.
30 The coating dev~ce is capable of recirculating the pellets through (a) a coat~ng zo~e, (b) a trying zone, and (c) a storage zone and ig therefore capable of apply~ng multiple coats of polymer to each pellet. In this ln-tauce the polymer is cellulose propionate morphollnobutyrate containing abol~t 3.0Z ba~ic nltrogen. The polymer 18 soluble in organic solvents ~uch as lower ~etones, lDwer esters, arcmatic hytrocarbon-alcohol mixtures, balogenated aliphatic hydrocsrbon-lower alcohol mixtures, ant water at a pH lower than about p~ 3Ø The polymer is di~olved in acetone at the level of 6Z by welght based on the total weight of the solution. The coating operation ls contlnued for the time necessary to coat e~sentially all the pellets with a layer of dry polymer about 0.006 lnch thick and compri ing about 17 to 20X of the final weight of the coated pellet.
D~ring the coating oper~tion samples of the coated pellets are obtained h~ving teposited about 5, 10 ant 15Z coating based on the total weight of the coated pellet. These pellets are tested for resistance to dissolution of the pellet at pH 5.5 and at pH 3.0 as a function of coating weight.
The test at pH 5.5 is conducted for 24 hours whereas the test at pH 3.0 ls for 1 hour. None of the pellets are stable to aqueous media at pH
values from 3.0 to 8Ø The pellets are also unstable in the rumen of sheep end cattle.
E~AMPLE 2 The lysine monohydrochloride pellets made by the process des-cribed in Exa~ple 1 are coated with a mixture composed of 60% by weight of cellulose propionate morpholinobutyrate and 40~ by weight of mono basic sluminum dioleate wherein these substances comprise 4% by weight of a solution of 90Z by ~olume methylene chloride and 10% by volume methanol. The pellets are coated in the ~ame manner as described in Example 1 and the final coating applied to the pellets comprises 20X by ~eight of the coated pellet. Sixty-five percent of the lysine monohydrochloride ls retained in pellets exposed to a~ueous media at pH 5.5 fter twenty-four hours. All of the amino acid is removed from the pellet by treating the pellet to pH 3.0 for 1 hour.

730 GrsYs of lysine ~onohydrochlorlde, 91 g. of basic magnesiu~
carbonaee, 73 g. of ~icrocrystalline cellulose having a partlcle size of 4~6 ~out 2S0 mesh and 73 g. gu~ arabic are dry mlxed to obtain an essentially ho~ogeneou6 powder. 250 Grs~s of water are ~ixed ~ith the powder mixture u~tll a plastlc dough-like consl3tency 18 obtai~ed. This dough is trudet, cut, rounted ~nd dried as descrlbed in Example 1. The pellets ~re then coated with the polymer mlxture deqcribed ln Example 2. The pellets contain$ng 20% by weight of dry coating are re~lstant to d~ssolution ~y e~posure to aqueous pH of 5.5 as shown by recovery of 94% of lysine ~onohydrochloride after 24 hour exposure. On exposure to aqueous pH of 3.0 or below the lysine monohytrochloride ls removed from the pellet wlthin l hour.
~XAMPLE 4 (Control) The pellets tescribed in Example 3 conta$ning lysine ~onohydro-chloride a~d bas$c magneslum carbonate are coated with 20% by weight of cellulose propionate morphol$nobutyrate. When tested for stabllity at pH 5.5, about 85~ of the lysine monohydrochloride ls leached from the pellets. The pellets are therefore not ~table at pH values typically fount in the rumen.

300 Grams dl-methlonine, 100 g. l-lysine monohydrochlorlde, 40 g. ~icrocrystalli~e cellulose and 135 g. water are thoroughly ~ixed to obtain A plastlc dough-like mass. This mixture is extruded and cut to o~tain ~oist pellets having a round cross section about 2 mm. and a l~.ngth of from 2 to 4 mm. The pellets are drled at 60C. to remove e~lsentially all free wster to obtain a hard psrtlcle havlng a denslty of ~out 1.05. A portion of the~e pellets are coated with a 6-mil layer of cellulose proplonate morphollnobutyrate. These pellets lose essentlally all of the s~lno acld comprising the core when exposed to queous media at pH 5.5 for 24 hours. A Qecond portion of pellets are coated with a 6-mil layer of coating compo~et of 50% cellulose proplonate morphollno-30 butyrate and 50% monobaslc aluminum dloleate. These coatet pellets arealso leached or tlssolved at pH 5.5. 300 Grams d,l-methlonlne, lO0 g.
l-lysine ~onohydrochloride, 40 g, microcrys~alllne cellulose, and 18 g.

~agneslum hydroxlde are dry blended, then mixed with water to obtain an extrutable dough. Pellets are nsde ac tescribed nbove. These pellets are coated with 8 6-mil layer composed of 50% cellulose propionate morpholinobutyrate aDt 50Z Dow-Corning XR129G. These pellets reslst losses of a~iDo acid~ fr~m the core on e~posure to p~ 5.5 for more than 24 hours a~ shown by recovery of 96%. The pellets readlly release lOOZ
of the core materlal ~ithin 1 hour on exposure to pH 3Ø Such mixtures e6sentlally hsve the propert$es of the more soluble and acltlc substance ~lth respect to rumen stablllty and abomasal release.
EXAMæLE 6 (Control) 500 Grams of hiRtidine monohytrochlorite are try mixed wlth 50 g. of mlcrocryRtalline cellulose. After thoroughly mixing the try powders, 145 g. of wster and atded and mixing is continued to obtain a plastic toughlike mass. This mixture i8 extrutet through a tie, ant as ; the extrudate appears on the outsite of the die, lt ls choppet or cut into lengths or segmeDts. The dimensions of the partlculate extrutate alfter cutting are 3/32 in. iD dlameter ant about 3/32 in. long. Next, the pellets are tumblet or rollet in a closet contaiDer so as to round the corners. The pellets formet by this operation are then dried at 60C. to essentlally remove all of the water. The pellets are then sieved to obtain about 90% yielt of pellets pass$ng through 8 mesh and retainet on 12 mesh. The pellets obtainet from the sieving operation are coatet iD a fluitlzet bed coater 80 that a coating of about 20Z by welght baset on the total welght of the coated pellets ls teposltet on the surface of the pellets. The actual film thlckness obtainet is about 4-~ ~ils of polymer. In thls instance, the polymer is a copolymer of 80Z 2-methyl-5-vinylpysltine ant 20Z sytrene. The polymer ls soluble in ecetone fro~ whlch lt 18 coated. The polymer I.V. ls about 0.5. The coated pellets are tested for lmpermeability or dissolutlon ~n an aq~eous solntlGn at pH 5.5. Ater 24 hours of contact with the acidic solutlon, the loss of the cose ~aterial within the pellets was determined to be about 75Z. In this e~smple, the pellets obtained are considered not bcing rumen stable. Another portion of the pellets is coated from ~olutlcn uslng a fluidlzed bed technique wlth ~ polymer lsyer co~po~ed of 50% of the copolymer described above and 50% of aluminum ~oap composed of monobaslc aluminum dioleate. In this ln~tance, the coating solvent uset is 8 ~isture of 90% of trlchloroethylene and 10%
methanol. A 5-6 mil layer of the dry polymer is deposltet on the pellets in this operatlon. The coated pellets are again evaluated for rumen ~t:ability by cxpos~ng the pellets for 24 hours to an acidic aqueous r~!dla at pH 5.5. At the end of 24 hours, examination of the pellets reveals that 65% of the histidine monohydrochloride is removed from the pellets. These pellets are al~o ~udged as bein~ unsuitable for rumen-stable feed supplements.
EXAM~LE 7 500 Grams of histidine monohydrochlorite, 50 g. of microcrystalline cellulose, and 50 g. of magnesium carbonate is dry mixed to obtain a hcmogeneous dry powder. Next, the mixture of try powters is mixed with 210 g. of water to obtain a plastic doughlike mass. Thls plastic dough is extruded throu~h a machine having a dle with holes 3/32 in. in diameter.
I~mediately outside the die face is a chopplng device which cuts the extruded rod lnto lengths about 3/32 in. long. After extrusion and cutting, the particles are tumbled in a drumlike device to cause rounding of sharp edges. The particles or pellets obtsined from the rounding operation are dried at 60C. until essentially all of the water is re~oved. The d~y pellets are then sieved to obtain about 907' of particles passlng through 8 mesh and retained on 12 mesh. A portlon of these pellets are then coated uslng a fluidized bed technique. A coating eanprising about 20% by weight of the coated pellet and having a film thickness of about 6 mils is spplied. The coated dry polymer is composed of about 50X of cellulose proplonaee morpholinobutyrate and 507' of a 30 metal salt having the ~nalysis of monobasic aluminum dioleate. This polymerlc ~ixture is coated from a 4~ solution of solids in a mixture of solvents co~posed of 90~ trlchloroethylene and lOZ methanol. The ccated 4~
pellets are tested by contactlng the pellets for 24 hr. to an aqueous acidic solutlon ~t p~ 5.5. At the end of 24 hr., the pellets are tested for retention of the histitlne ~onohydrochloride within the pellet. In this instance, the pellet loses o~ly 8.5X of the histidine monohydrochloride.
The pellets are then tested for dissolution and/or 1068 of the histidine monohytrochloride in squeous solutlon at pH 3Ø At the cnd of 1 hour, it is determined by testing that essentially all of the pellets lose the hl~tldlne monohydrochlor~de. These pellets are suitable for use as a feed oupplem¢nt for ruminant an~m~l 8.
10 ExAMpLE 8 40 Grams of cellulose propionate morpholinobutyrate and 13 g.
of oleic acid (0.047 equivalents) are dissolved in a solvent mixture containing 900 ml. of trichloroethylene, 100 ml. methanol, and lO0 ml.
dichloromethane. The contained solids are coated on 150 g. of pellets composed of 83% lysine monohydrochloride, 6X calcium carbonate, and 11 of suitable binders uslng a fluidized-bed process. The coated pellets retain 48% of the contained lysine following 24 hours of agitation with pH 5.5 aqueous buffer and release 100% of the contalned amino acid during a one-hour agitation period in the presence of pH 2.9 aqueous 20 buffer.

This example i8 identical to Example 8 with the exception that 0.094 equivalents of oleic acid is included in the coating composition.
The coated pellets retain 54.5% of the contained lysine following the 24 hour pH 5.5 buffer extraction and release 100~ of the amino acid ln one hour of agitation at pH 2.9.

~ his example is identical to Example 8 ~ith the exception that 0.047 equivalents of ~tearic ~cid 18 substituted for the oleic acid.
Seventy-one percent of the pellet sample remains intact following a 24 hour agitation period wlth p~ 5.5 aqueous buffer.

~1~4496 EXAMPLE_Il ~ nis example is identical to Example 8 witb the exception that 0.094 equivalents of Empol 1010 (trademark) Dimer Acid (a C36 aliphatic dibasic acid, Emery Industries, Inc., Cincinnati, Ohio) is substituted for the oleic acid. ~ne coated pellets retain 90% of the contained amino acid following 24 hours of extraction with pH 5.5 buffer and releases 100% of the contained lysine during one hour of agitation with pH 2.9 buffer.

A copolymer of 80% 2-methyl-5-vinylpyridine/20% styrene, and dodecanoic acid calculated to be equivalent to tbe basic function present, dissolved in trichloroetnylene or other suitable solvent, coated on methionine pellets results in a useful nutrient composition for ruminants.

In the examples in the following table, the coating is approximately 20% of the weight of the pellet. ~ne results are shown in the form of percent pellets retained and percent pellets released at the different environnental condition.

4~96-~. ~ .
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. - 37 -~1~4~96 ~ne present invention therefore provides pellets adapted for oral administration to a ruminant comprising a core material having a pH greater than about 5.5, said core material being beneficial to the rl~minant postruminally, and a coating surrounding said core material, said coati.ng being resistant to pH conditions of about 5.5 for at least s:ix hours and adapted to release pellet core material after exposure to u a pH of about 3.5 after a time of from about 10 minutes to about six hours and comprising a) a film-forming polymeric material containing at least one basic amino grouping and in which the nitrogen content is from 3 to 14% by weight of the total molecular weight of the polymeric material, said polymeric material consisting essentially of at least one polymer, copolymer or blend of polymers selected from the group consisting of cellulose propionate morpholinobutyrate, aromatic basic amino-containing polymers, dialkylamino ethyl acrylates and methacrylates in which the alkyl group contains from 1 to 6 carbon atoms, condensation polyesters and polyamides, and : 20 b) a hydrophobic material dispersed in said polymeric ; material selected from the group consisting of waxes, resins, polymers, fatty acids having from 12 to 32 carbon atoms, aluminum salts of fatty acids having fro~
l2 to 32 carbon atoms, and polyfunctional carboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight of from 400 to 1000, said hydrophobic material being present in an amount between about 5 and about 50% of the weight of the polymeric material, and said coating making up about 5 to about 50% of the weight of said pellet, and having a sticking temperature of at least about 50C.

~3 ' 11~4~6 Unless otherwise specified, all percentages, ratios, parts, etc. are by weight.
The fluid used to simulate environmental conditions of the rumen (at pH 5.5) is prepared by mixing 11.397 grams of sodium acetate with 1.322 grams of acetic acid and diluting this mixture with de-mineralized water to I liter.
~ ne fluid used to simulate environmental conditions of the abomasum (at pH 2.9) is prepared by mixing 7.505 grams glycine with 5.85 grams sodium cnloride and diluting this mixture with demineralized water to 1 liter. Eight parts of tnis solution are mixed with 2 parts of 0.1 normal hydrochloric acid for the teYt fluid.
~ ne fluids are found to give reliable results in testing the pellets, according to similar experiments using actual rumen and abomasal fluid withdrawn from a ruminant.
To be useful and practical as a feed for ruminants, it is considered that at least 60% and preferably at least 75% oE the active ingredients of the core of tne pellets to which this invention relates should be stable in the nlmen and release in the abomasum.
~ ne invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

. . , .~ .

~ - 38a -' -.`. 1

Claims (18)

We Claim:

1. A pellet adapted for oral administration to a ruminant comprising a core material having a pH greater than about 5.5, said core material being beneficial to the ruminant postruminally, and a coating surrounding said core material, said coating being resistant to pH conditions of about 5.5 for at least six hours and adapted to release pellet core material after exposure to a pH of about 3.5 after a time of from about 10 minutes to about six hours and comprising a) a film-forming polymeric material containing at least one basic amino grouping and in which the nitrogen content is from 3 to 14% by weight of the total molecular weight of the polymeric material, said polymeric material consisting essentially of at least one polymer, copolymer or blend of polymers selected from the group consisting of cellulose propionate morpholinobutyrate, aromatic basic amino-containing polymers, dialkylamino ethyl acrylates and methacrylates in which the alkyl group contains from 1 to 6 carbon atoms, condensation polyesters and polyamides, and b) a hydrophobic material dispersed in said polymeric material selected from the group consisting of waxes, resins, polymers, fatty acids having from 12 to 32 carbon atoms, aluminum salts of fatty acids having from 12 to 32 carbon atoms, and polyfunctional carboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight of from 400 to 1000, said hydrophobic material being present in an amount between about 5 and about 50% of the weight of the polymeric material, and said coating making up about 5 to about 50% of the weight of said pellet, and having a sticking temperature of at least about 50°C.

2. A pellet according to Claim 1 wherein said polymeric material is at least one polymer selected from the group consisting of cellulose propionate morpholinobutyrate, acrylonitrile, vinyl pyridine, styrene, methacrylate and methyl methacrylate.

3. A pellet according to Claim 1 wherein said amorphous hydrophobic material is selected from the group consisting of fatty acids having from 12 to 32 carbon atoms, aluminum salts of fatty acids having from 12 to 32 carbon atoms, and polyfunctional carboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group.

4. Method for producing a pellet adapted for oral administra-tion to a ruminant comprising a core material having a pH greater than about 5.5, and a coating surrounding said core material which comprises the steps of forming a coating composition being resistant to pH
conditions of about 5.5 for at least six hours and adapted to release pellet core material after exposure to a pH of about 3.5 after a time of from about 10 minutes to about six hours and comprising a) a polymeric film-forming material containing at least one basic amino grouping in which the nitrogen content is from 3 to 14% by weight of the total molecular weight of the polymeric material and having a solution viscosity of from about 5 to about 30 centipoises, said polymeric material consisting essentially of at least one polymer, copolymer or blend of polymers selected from the group consisting of cellulose propionate morpholinobutyrate, aromatic basic amino-containing structures, dialkylamino ethyl acrylates and methacrylates, condensation polyesters and polyamides, and b) a hydrophobic material dispersed in said polymeric material selected from the group consisting of waxes, resins, polymers, fatty acids having from 12 to 32 carbon atoms, aluminum salts of fatty acids having from 12 to 32 carbon atoms, and polyfunctional carboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight of from 400 to 1000, the weight of said hydrophobic substance being from about 1 to about 50% of the combined weight of polymeric material and hydrophobic substance, and applying said coating to a core material which is beneficial to the ruminant when supplied postruminally upon reaching the abomasum in an amount such that said coating makes up about 5 to about 50% of the weight of said pellet.

5. A pellet adapted for oral administration to a ruminant comprising a core material having a pH greater than about 5.68, said core material being beneficial to the ruminant postruminally, and a coating surrounding said core material, said coating being resistant to pH conditions of about 5.5 for at least 6 hours and adapted to release pellet core material after exposure to a pH of about 3.5 after a time of from about 10 minutes to about 6 hours and comprising a) a film-forming polymeric material containing at least one basic amino group in which the nitrogen content is from 3 to 14% by weight of the total molecular weight of the polymeric material, said polymeric material consisting essentially of cellulose propionate morpholino-butyrate, and polymers, copolymers and blends of polymers derived from monomers selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, and 2-ethyl-5-vinylpyridine, and b) a hydrophobic material dispersed in said polymeric material selected from the group consisting of fatty acids having from 12 to 32 carbon atoms, aluminum salts of fatty acids having from 12 to 32 carbon atoms, and polycarboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight of from 400 to 1000, said hydrophobic material being present in an amount between about 5 and 50% of the weight of the polymeric material, and said coating making up about 5 to about 50% of the weight of said pellet, and having a sticking temperature of at least about 40°C.

6. A pellet according to Claim 5 wherein said core material is selected from the group consisting of L or DL mixtures of isomers of alanine, arginine, methionine, and tyrosine.

7. A pellet according to Claim 5 wherein said polymeric material is cellulose propionate morpholinobutyrate.

8. A pellet according to Claim 5 wherein said polymeric material is a copolymer of 2-methyl-5-vinylpyridine and styrene.

9. A pellet according to Claim 7 wherein said polymeric material is a copolymer consisting essentially of about 80% 2-methyl-5-vinylpyridine and about 20% styrene.

10. A pellet according to Claim 5 wherein said hydrophobic material is aluminum oleate.

11. A pellet according to Claim 5 wherein said hydrophobic material is stearic acid.

12. A pellet according to Claim 5 wherein said hydrophobic material is dimer acid.

13. A composition adapted for coating pellets orally admin-istrable to a ruminant being resistant to pH conditions of about 5.5 for at least six hours and adapted to release pellet core material after exposure to a pH of about 3.5 after a time of from about 10 minutes to about six hours and comprising a) a film-forming polymeric material containing at least one basic amino group in which the nitrogen content is from 3 to 14% by weight of the total molecular weight of the polymeric material, said polymeric material consisting essentially of cellulose propionate morpholino-butyrate, and polymers, copolymers and blends of polymers derived from monomers selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, and 2-ethyl-5-vinylpyridine, and b) a hydrophobic material dispersed in said polymeric material selected from the group consisting of fatty acids having from 12 to 32 carbon atoms, aluminum salts of fatty acids having from 12 to 32 carbon atoms, and polycarboxylic acids having a ratio of from 10 to 22 carbon atoms per carboxyl group and a molecular weight of from 400 to 1000, said hydrophobic material being present in an amount between about 5 and about 77% of the weight of the polymeric material.

14. A composition according to Claim 13 wherein said polymeric material is cellulose propionate morpholinobutyrate.

15. A composition according to Claim 13 wherein said polymeric material is a copolymer of 2-methyl-5-vinylpyridine and styrene.

16. A composition according to Claim 13 wherein said hydrophobic material is aluminum oleate.

17. A composition according to Claim 13 wherein said hydrophobic material is stearic acid.

18. A composition according to Claim 13 wherein said hydrophobic material is dimer acid.