Note: Descriptions are shown in the official language in which they were submitted.
This invention relates in general to pellets adapted to be
orally administered to ruminants and which are beneficial to ruminants
after passing the rumen and reaching the abomasum and/or intestines.
~ore particularly, this invention relates to pellets having, in terms of
structure, a core material such as a nutrient or medicament, and an
imperforate coating over the core material which protects the core in
the environment of the rumen, but which loses continuity under the more
acidic conditions of the abomasum to render the core material available
for utilization by the animal.
In ruminants, ingested fe'ed first passes into the rumen, where
it is pre-digested or degraded by fermentation. During this period of
fermentation the ingested 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 variable depending on the animal
and the feedstuff, adsorption of digested nutrients starts and contlnues
in the subsequent sections of the digestive tract by the ruminant animal.
This process is described in detail by D. C. Church, "Digestive Physiology
and Nutrition of Ruminants", Vol. 1, O.S.~. 300k Stores, Inc., of
Corvallis, Oregon.
The rumen, the largest of the four stomach compartments of
ruminants, serves as an important location for metabolic breakdown of
ingested foodstuffs through the action of microorganisms which are
present therein. Ingested food is typically retained in the rumen for
from about 6 to 30 hours or longer in some ir.stances, during which time
it is subject to metabolic breakdown by the rumen microorganisms. ~uch
ingested protein material is broken down in the rumen to soluble peptides
and amino acids and utilized by the rumen microorganisms. When the
rumen contents pass into the abo~asum and intestine, the microbial mass
is digested, thus providing protein to the ruminant. Thus, the natural
30 nutritional balance of the ruminant animal is primarily a function of
the microbial co~position and population.
In preparing nutrients and ~edicaments intended for administration
2 .~
to ruminants, it is important to protect the active ingredients against
the environmental condltions of the rumen, i.e., microbial degradation
and the effects of a pH of about 5.5, so the active substance will be
saved until it reaches the particular location where adsorption takes
; place. It is well known that the rate of meat, wool and/or milk pro-
duction can be increased if sources of growth limiting essential amino
acids, and/or medicaments, are protected from alteration by microorganisms
residing in the ru~en and become available for direct absorption by the
animal later in the gastrointestinal tract.
10Materials which protect the core against degradation by the
rumen contents should be resistant to attack by the rumen fluid which
contains enzymes or microorganisms but must make the active ingredient
available rapidly in the more acidic fluid of the abomasum at a pH
within the normal physiological range of about 2 to about 3.5. To more
easily coat or encapsulate active ingredients in protective materials,
; ~ the protective materials should be soluble in certain organic solvents
for coating purposes.
; ~ Because proteins are subject to breakdown in the rumen, it has
been suggested that protein-containing nutrients fed to ruminants be
treated so as to permit passage without microbial breakdown through the
rumen to the abomasum. Suggested procedures have included coating the
protein material, for example, with fats and vegetable oils; heat treating
of the protein material; reacting the protein material with various
compounds such as formaldehyde, acetylenic esters, polymerized unsaturated
~` carboxylic acid or anhydrides and phosphonitrilic halides, etc.
It is well known that all proteins found in animal and plant
life are chemical compounds containing different combinations of over 20
amino acids, the number and arr2ngement of such acids being fixed in any
particular protein. Twelve of these amino acids can be synthesized in
nutritionally adequate amounts from other substances by biochemical
processes normally present in most anim21s, but the remaining 10 essential
amino acids are not synthesized in sufficient quantities and must be
-- 3 --
9~
ingested by the animal. Since the proportions of the constituent amino
acids in a particular protein cannot be varied, the essential amino acid
least in supply limits the amount of that protein which can be produced
by the animal. Consequently, for any given diet, there will be a parti-
cular essential amino acid which limits the production of protein incor-
porating that essential amino acid unless, of course, two or more such
amino acids are equally limiting.
The appreciation of the above principles leads to the formula-
tion of diets for nonruminant animals which provide the optimum proportion
of amino acids and have enabled sighificant increases in protein production
to be achieved. In the ruminant, dietary proteins and amino acids are,
to a variable extent, broken down to ammonia and various organic compounds
by microbial fermentation in the first two compartments of the stomach
(the rumen and reticulum). The bacteria and protozoa in these organs
utilize these metabolites for their own growth and multiplication and
the microbial protein so formed passes on to the abomasum, the compart-
ment of the stomach corresponding to the stomach of nonruminants, where
it is partially digested. The process is completed in the small intestine
and the amino acids are absorbed.
It is likewise well-k~own that medicaments are more effective
when they are protected from the environment of the rumen. See, for
example, U.S. Patent Nos. 3,041,243 and 3,697,640.
In accordance with the present invention, normally acidic core
materials are raised in pH such that the pH is at least above about 5.5,
and typically between about 5.5 and about 7 by the addition of a physio- -
logically acceptable basic substance. The core neutralization, in
con~unction with a polymeric coating having a hydrophobic substance
dispersed therein, which is resistant to environmental conditions of the
` rumen but releases the core material under the environmental conditions
of the abomasum, provides a very desirable utilization efficiency by
ruminants.
The coating material has the ability to withstand environmental
-- 4 --
ilfJ~
conditions of the rumen, and the ability to expose the core mater-
ial 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 mater-
ial upon exposure to abomasum environmental conditions having a pH
of about 3.5 after a time of 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 significant amount of blocking.
Core materials having an adjusted pH of greater than
about 5.5 and a water solubility of about 10 to about 70 grams
per hundred grams water at 25C. are most useful in this invention.
Thus, any core material which is beneficial to the ruminant such
as a nutrient or medicament having characteristics within these
parameters may be used. Preferred core materials include amino
acids, proteins, various other nutrients, as well as antibiotics
and other medicaments.
Thus, in accordance with the present teachings, a method
` is provided for preparing pellets which have a core material and
coating and which are adapted for oral administration to ruminants
wherein the core material is beneficial to the ruminant postrumin-
ally. The method comprises a) mixing with the core material a
basic substance selected from the group consisting of magnesium
oxide, magnesium hydroxide, magnesium carbonate, calcium oxide,
calcium hydroxide, calcium carbonate, basic aluminum acetate and
aluminum hydroxide in sufficient quantities to raise the pH of
.
~ -5-
11~4~9~
the mixture above about 5.68, b~ forming the mixture into a
self-supporting pellet, and c) coating the mixture with a material
which is resistant to attack from the environment of the rumen
but susceptible to breakdown in the abomasum, the coating has a
sticking temperature of greater than about 50C. and it is resistant
to p~ 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.
The coating comprises a film-forming polymeric material which con-
tains at least one basic amino grouping in which the nitrogen con-
tent is from 3 to 14~ by weight of the total molecular weight of
the polymeric material, with the polymeric material consisting
essentially of at least one polymeric, copolymer or blend of
polymers selected from the group consisting of cellulose propion-
ate 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 a hydrophobic material which is dispersed in
the polymeric material and is selected from th~ group consisting
of waxes, resins, polymers, fatty acids which have from 12 to 32
carbon atoms, aluminum salts of fatty acids which have from 12 to
32 carbon atoms and polyfunctional carboxylic acids which have a
ratio of from 10 to 22 carbon atoms per carboxyl group and a
molecular weight of from 400 to 1000.
As an alternate method the core material may be formed
: into a self-supporting pellets and the first coating of the basic
.~ -5a-
l~t4~
substance may then be applied.
BACKGROUND
U.S. Patent No. 3,619,200 relates to chemically modify-
ing pellets and/or using a surface coating therefor. Proteinaceous
feed is protected from breakdown within the rumen by the modifica-
tion of protein itself, by the application of a protective coating
to the feedstuff, or by combination of both. Various polymers are
disclosed in this patent including copolymers of vinylpyridine and
styrene. Canadian Patent No. 911,649 discloses treatment of pro-
teinaceous materials with substances which are capable of react-
ing with proteins to form a polymeric proteinaceous complex on the
surface of the material or by treating the proteinaceous material
; with the 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 acrylate or methacry-
late monomer and at least one ethylenically unsaturated compound
as rumen stable coatings. U.S. Patent 3,880,990 and British
Patent No. 1,346,739
~.
~ -5b-
'. ~.
~'
,
-
,
~1~4~94
relate to an orally administratable ruminant composition wherein a
medicinal substance is ~ncapsulated or embedded in a normally solid,
physiologically acceptable basic polymer. The compositions are produced
by dispersing a medicinal substance in a first solvent and adding thereto
a second solvent which is miscible with the first solvent but in which
the polymer and medicinal substance are substantially insoluble. There
is no suggestion of modifying the polymer by the use of additives. U.S.
Patent No. 3,041,243 relates to coatings for oral medicaments. These
coatings are water-insoluble but acid-soluble film-forming polymers. An
example mentioned in this patent is 2-methyl-5-vinyl pyridine copolymerized
with vinyl acetate acrylonitrile, metnyl acrylate or styrene.
U.S. Patent No. 3,697,640 relates to materials such as medicaments
and nutrients for ruminants which are coated with nitrogen-containing
cellulosic materials such as, for example, cellulose propionate morpholino
butyrate. This patent, however, fails to suggest the use of any additives
in the nitrogen-containing cellulosic material, and U.S. Patent No. 3,988,480
relates to a proteinaceous feedstuff for ruminants which has been treated
with acetic acid to render it rumen stable.
U.S. Patent No. 3,383,283 relates to coating pharmaceutical
pellets with a plurality of charges of fatty acid as a melt or in solution.
The fatty acid may then be dusted with a fine inert powder such as talc.
There is no suggestion of using a continuous matrix polymer.
U.S. Patent No. 3,275,518 relates to a tablet coating composition
comprising a film-forming resin or plastic and a hard water-soluble or
water-dispersible substance. Stearic acid is mentioned as an optional
water-insoluble wax which may be included as an additive. Additional
~; materials such as dyes, pigments, water-insoluble waxes, plasticizing
agents, etc., may also be added to the coating. However, the film-
forming resin or plastic according to this patent is selected from the
group consisting of poly(methylstyrene), methylstyrene-acrylonitrile
copolymers, poly(vinylchloride), poly(vinyl butyral), pentaerythritol or
alkyd esters of rosin or modified rosin and terpene derived alkyd resins.
There is no suggestion of the polymers according to ap~licants' invention.
In fact, the plastic or resin is described as ~ater-permeable, and the
coating apparently is not designed or ruminants.
U.S. Patent No. 3,623,997 relates to a method of sealing
polymeric material walls of minute capsules by treating the capsules
with a waxy material. The wax is introduced in a solvent which is
subsequently dried and the wax is left as a residue in the walls. The
capsule walls shrink and lose solvent and then entrap the wax tightly as
a sealing material. There is no indication, however, that the polymer
coating is designed to function for ruminants, and the wax is used as a
sealing ~a.erial. A??lisant's hydrophobic subs~ance is dis?ersed in the
polymer.
U.S. Patent No. 3,073,748 relates to tablets coated with a
solution of an amphoteric film-forming polymer. The polymer is described
as one selected from the group consisting of copolymers of (a) vinyl
pyridines with (b) a lower aliphatic ~,~-unsatur2ted monocarboxylic acid
of 3 to 4 carbon atoms and copolymers of (a), (b) and a neutral co-
monomer selected from the group consisting of methyl acrylate, acrylonitrile,
vinyl acetate, methyl methacrylate and styrene. There is no suggestion
of using a dispersed ~dditive.
British Patent No. 1,217,365 and Canadian counterpart No. 8;i,128
relate to a particulate feed additive composition for ruminants wherein
each particle comprises one or more amino acids totally encased in a
continuous film of protective material which is transportable .hrough
the rumen without substantial degradation therein but which releases the
active substance posterior to the omasum when the particles have a
density within the range of 0.8 to 2.0 and diameters in the range of 200
. . .
to 2,000 microns. Suggested as protective materials are fatty acid
triglycarides such as hydrogenated vegetable and animal fats, waxes such
as rice-brand wax, and resin wax blends which are emuisified and/or
dissolved in the intestinal tract.
-
PELLETS
The pellets according to this invention are adapted for oraladministration to a ruminant. The pellets are of a suitable size, such
as between about 0.05 in. and 0.75 in. in diameter. Also, the pellets
must be of suitable density, i.e., a specific gravity of between about l
and 1.4, have acceptable odor, taste, feel, etc. The pellets include a
core and a continuous, film or coating completely encapsulating the
core. The shape is usually not critical, except the pellets are commonly
spherical for ease in coating.
CORE M~TERI~L
The core is of a material beneÇicial to ~he ruminant upon
passing the rumen and reaching the abomasum and/or intestine. Normally,
the core is a solid material which has been formed into particles, such
as by pelletizing. The cores may then be rounded if desired, by con-
ventional means, such as by tumbling. The core should have sufficient
body or consistency to remain intact during handling, particularly
during the coating operation. Suitable core materials include various
medicaments and nutrients such as, for example, antibiotics, relax~n~s,
drugs, anti-parasites, amino acids, proteins, sugars, carbohydrates,
etc. The core may also contain inert filler mate-ial such as clay.
It has been discovered that the ability of the coating to
protect the core is related to the pH and water solubility of the core.
The core materials to which the present invention is applicable are
those described above having a pH, after mixing with a basic substance, of
greater than about 5.5 and a water solubility at 25~C. of less than
about 80 grams ?er 100 grams water.
Some amino acids suitable for use as a core material, their pH
and solubility are as follows:
Amino Acids Solubility and ?H of Saturated Solutions
Solubility g./100 g. water
at_25C. pH
DL - Alanine 16.7 6.2
L - Asparagine 3.1 4.7
-- 8 --
11~4~
L - Arginine 21.6 11.8
L(-) - Cysteine 0.01 3.7
DL - Methionine 4.0 5.7
L(-) - Leucine 2.0 4.8
L(-) - Tyrosine 0.05 7 3
DL - Phenylalanine 3.0 5.6
Proteins from various sources are valuable for practice of the
invention. Generally, proteins are poly~ers derived from various combinations
of amino acids. Proteins are amphoteric substances which are soluble or
suspendable in aqueous media either more acidic or more basic than the
; particular ?rotein being considered.
The core material may be made ready for coating by the following
method. The nutrient, medicament, or the like, and core neutralizer (as
described more specifically below) are mixed with water, binders, and
sometimes inert inorganic substances added to adjust 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 oe nontoxic vegetable gums,
starches, cellulose derivatives, animal gums and other similar sub-
stances well-known in the art of food thickening and tablet making.
Inorganic additives used to adjus~ .he 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
density. The final desirable range of specific gravity for the rumen
protected pellets is from 1.0 to 1.4. After creating suitable si~e
pellets by extrusion, rolling or other suitable means, the pellets are
dried to remove the water. lhe pellets are then coated by contacting
them with a solution of the protective coating material in a auitable
~ solvent or mixture of solvents as hereinafter described. Typical
; 30 solvents of value include lower alcohols, ketones, esters, hydrocarbons,
and chlorinated hydrocarbons.
_ g _
11~4~
CORE NEUTRALIZATION
In accordance with this invention, core materials are raised
in pH to a predetermined degree by mixing a basic neutralization substance
therewith or by coating the core with a basic neutralization substance.
Normally, the core materials are originally acidic, and the pH is
raised to at least about 5.5, typically to about 7. The acidity is
modified by adding nontoxic, insoluble, basic substances such as alkaline
earth oxides, hydroxides, or carbonates, to the core material before the
pellet forming step. Basic compounds of aluminum such as the various
forms of hydrated alumina, aluminum~hydroxide, and dibasic aluminum
salts of organic acids, naving less than o carbor. atoms, such as dibasic
aluminum acetate may also be used. These basic substances are added to
the pellets by mixing the core material, basic substance, and binders as
described above before adding water. The amount used depends on both
the solubility and relative acidic nature of the proteinaceous substance,
on the coating composition used to obtain rumen protection and on the
thickness of the coating applied. The amount of basic substance used is that
quantity which will theoretically neutralize or raise the pH at least to -
5.5, preferably to about 7.
While we do not wish to relv on anv particular theory as to
why the coatings are effective when the basic core material is added to
or coated on the core material, it may be true that when the core material
is acidic, the water which permeates the film ioniæes the acidic groups
and they in turn react with the amino groups in the polymer and in time
dissolve the polymer from inside the capsule. When the core material is
both soluble and acidic, both destructive forces operate and the protective
film is quickly rendered ineffective as a rumen-stable coating.
At the same time, the solubility of the polymer at pH below
about 3.0 has not been altered because, as an increment of polymer
actually dissolves, the disperse phase hydrophobic substance is removed
by ablative processes and eventually the polymeric film is destroyed.
The theoretical function of the basic substance added to the core material
... .
-- 10 --
11~4~
is that it acts as a reserve of basicity. This is, any water
which tends to ionize the acidity of the pellet also permits
neutralization of such acidity and the attack on the protective
film is prevented.
The core material may be neutralized by the follow-
ing method. Nontoxic, incoluble basic substances such as
oxides, hydroxides, carbonates, and basic salts of magnesium,
calcium, and aluminum are blended with finely-divided nutrient
and/or therapeutic substances at the time these are prepared
for pelletizing. The amount of basic substance used depends
on several interacting factors related to the relative
acidity and/or solubility of the pellet, the time required
for rumen protection, and the time required for release in
the abomasum. Normally, the weight of basic substance will
be within the range of 1-20% of the total weight of the core.
In addition to the nutrient or therapeutic substance and
the basic substance, the pellets may contain binders,
density modifiers, and other minor ingredients required
for special properties, as is common practice in the art of
tablet making. In this practice of the invention, the
various powdered ingredients are first dry blended to
obtain a more or less homogeneous mixture, then water is
added to obtain a plastic dough-like mass. The dough is then
pelletized by extrusion, extrusion and tumbling, or by any
method known to the art of pelletizing or tabletmaking. The
water is removed by drying at ambient conditions, in heated
ovens, or fluidized beds. The dry pellets are then ready for
subsequent coating operations performed by any method such
as pan coating, fluidized bed coating, or spray coating or
combinations thereof.
Another method of core neutralization is based
on the concept that, whereas the coating is permeable to water
- ~
and acidic water borne molecules, not all of the pellet
interior is required to be neutralized. In this method
of practicing the invention, the nontoxic inorganic basic
substances are deposited on the surface of the core material
prior to application of the coating. In practice, the pre-
formed pellets are placed in a fluidized bed or other coating
apparatus and a dispersion of an oxide, hydroxide, carbonate,
or basic salt of magnesium, calcium, or
~ 20
:
- lla -
~.
11~4~3~
aluminum in water or an organic liquid is sprayed on the pellet. The
dispersion of basic substance preferably contains a binder and may also
contain a protective colloidal substance wherein the ratio of binder
plus protective colloidal substance to basic substance i3 less than
about 1:3. The amount of basic substance coated onto the pellet is
normally from about 1 to about 20% of the weight of the core material.
The binder and protective colloidal substance can be the same substance
or different and are preferably soluble or dispersible in water and in
the organic liquid used to sllspend the basic substance. Such binder
materials as relatively low molecular weight cellulose derivatives,
synthetic polymers, and natural g~ms ~nown to the art of tablet making
are suitable for the practice of the invention. The organic liquid can
; be any having suitable solvent power and boiling in the range of from
40-140C.
COATI~G
; 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 pellet in the environment
of the abomasum. T~.us, the coating material should be resistant to pH
conditions of greater than about 5 (37C.) for from about 6 to about 30 hours.
The coating material should release the core material after exposure to
abomasum environmental conditions having a pH of about 2 to about 3.3 (37C.).
Release should occur within the residence time in the abomasum or later
in the intestinal tract but at least within a time period of 6 hours
after contacting p~ 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
is physiologically acceptable, i.e., the coating material should not
~- 30 interfere with the ruminants' healthy or normal body functioning.
Another requirement for the coating material is its ability to
withstand storage conditions of relatively high heat and/or humidi~y
- 12 -
without a significant amount of blocking. It should have a sticking
temperature of greater than about 50C. Sticking temperature is defined
as the temperature 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/cm holds the particles in contact for
24 hours. Also, the coating material 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,
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 and accounts for about 23 to about 95~ of the coating weight.
Generally, the more acidic and more soluble core materials re~uire
greater ratios of hydrophobic substance to polymeric substance, while
~ore basic and less soluble core materials require lesser ratios of
hydrophobic substance to polymeric substance within this range. The
hydrophobic substance is normally dispersed in the polymeric matrix, and
is present in amounts of between about 5 and 50%, based on the weight of
the polymeric material.
POLYMER
The polymeric substances which are useful in the coatings of
this invention include those which, in combination ~ith the hydrophobic
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.
The polymeric substances are macromolecules of sufficient
molecular weight to have film-forming properties when the polymer is
deposited from a solution and after removal of a solvent, dispersing
~1~4~9~
medium or on cooling from a melt. Typical molecular weights will be in
the range of from about 5000 to about 300,000.
Polymeric substances having the characteristics defined herein
include certain modified natural polymers, homo- and interpolymers. The
polymeric material is at least one poly~er, copolymer, or blend of
polymers selected f~om the group consisting of cellulose propionate
morpholinobutyrate, poly(vinylpyridine), and polymeric derivatives of
vinylpyridine. Especially preferred is a copolymer of about 75-85% by
weight 2-methyl-5-vinylpyridine and about 15-25% by weight styrene.
Preferred also are copolymers of derivatives of vinylpyridine
and acrylonitrile, and in particular, the copolymer of about S5-65% by
weight 2-methyl-5-vinylpyridine and about 35-45% by weight acrylo-
nitrile. These copolymers are commercially available or may be produced
by conventional techniques well known in ~he art.
IIYDROPHOBIC SUBS~NCE
Useful hydrophobic substances which are physiologically
; acceptable are commercially available. The polymer and hydrophobic
substance should have a degree of compatability to permit the film to
remain intact in the rumen environment, but to permit permeation of the
20 abomasal fluid to the core while the pellet is in the abomasum.
Suitable hydrophobic substances include fatty acids, dimer
acids, trimer acids, and aluminum salts of fatty acids. lhe useful
'nydrophobic substances are fatty acids having from 12 to 22 carbon atoms
such as, for example, oleic acid and stearic acid. Aluminum salts of
such acids, for example, aluminum oleate, aluminum stearate, aluminum
dimerate, are also useful. Also, the hydrophobic material may be one or
more polycarboxylic acids having a ratio of from 10 to 22 carbon atoms
per carboxyl group and a molecular weight of from about 400 to about
1000. Blends of these acids and/or salts are also useful.
Inert filler materials such as clay, bentonite, limestone,
etc., may also be used in suitable amounts.
- 14 -
11(;~4494
APPLICATION OF COATING
.. _ _ . .. . .
In the practice of this invention, the polymeric material
may conveniently be dissolved in a suieable organic solvent which would
be physiologically acceptable in the event there are residues upon
evaporation of the solvent, 2S hereinbefore described. The hydrophobic
substance is blended in the solution, wherein the polymeric substance i8
a continuous matrix and the additives are dispersed therein. The coating
solution may be applied by various well known means such as, for example,
brushing, dipping, spraying, fluidized bed, etc.
A preferred apparatus and~ process for coating the cores will
now be described.
In the d~awings:
Fig. 1 is an elevation view in cross-section illustrating the
apparatus and showing the gas flows and particle flow path from 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
modified apparatus and illustrating the addition of an annular airfoil
; and showing the flow of gases relative to the aerodynamic structure and
anr.ular airfoil;
Fig. 3 is a partial elevation view in cross-section of another
modified apparatus similar in all other respects to the modification
shown ln Fig. 2 except that the cross-section of the apparatus 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 apparatus of the invention for illustrating one
possible manner of collecting the finally coated particles by use of an
air porous bag; and
Fig. 5 is a graphic illustration of the height, thickness and
.
angular relationships of the annular airfoil with respect to the aero-
dynamic structure, and the height above (h ) and height below (hb)
relationships of the aerodynamic structure to the greatest cross-
- 15 -
-
~1~4~9~
sectional diameter of the aerodynamic structure.
The apparatus employs a truncated hollow cone in which the
slope 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 pi~ch 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 through the cone. In this manner a separation is
brought about between the particles so that after they are coated they
may become sufficiently dry before coming into contact with other particles
and thereby avoid undesirable clumping or agglomerating 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 coating apparatus is designated in
general at 10 and includes a vertically disposed first hollow column 12
of regular shape. By ''regular shape" is meant that it may be cylindrical,
octagonal, hexagonal or of other configurations, so long as the hollow
column is generally symmetrical with respect to its central axis. The
hollow column contains therewithin the particle storage, coating, drying
and deceleration zones, which will be described herein.
A truncated hollow cone 14, which may also be a tapered oc~agon
or other tapered polygonal configuration, in other words, generally
cone-shaped configurations, serving as an enclosure in which the upwardly
flowing gases are received, compressed and accelerated, is centrally
disposed within the first hollow column, has a uniformly decreasing
cross-section in the upward direction and is or predetermined height
dependent upon the size and weight of the particle to be treated.
13,r~
Within the truncated hollow cone in ascending order are the coating and
drying zones. The cone serves also to separate the coating and drying
zones from the deceleration zone, which lies in the region above the
upper end of the cone, and from the storage zone, which lies therebetween
the cone 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
hollGw column, the wa'l surface of the inwardly tapered base forms a
juncture with the wall surface of the second hollow column.
Disposed within the second hollow column is a first plenum
chamber 20 into which a suitable compressed gas, such as air, may be
provided through two or more opposed inlets 22, 24; a gas or air colli-
mating plate 26; a second plenum chamber 28 separated from the first
plenum 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
second plenum chamber in an essentially vertical and uniform flow, as
illustrated by the vertical arrows.
The gas shaping or aerodynamic structure 30 in cooperation
with the ad~acent 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
30 hollow cone. The flow upwardly around ehe aerodynamic structure constitutes
an annular flow, which adheres to the surface of the aerodynamic structure
in the nature of a Coanda flow.
- 17 -
1 1~J~4 ~ ~ ~
A spray nozzle 34 prefera~ly extends above the top of the
aerodynamic structure 30 through which is sprayed a suitable coating
material. It is more convenient to have the spray nozzle located at the
top of the centrally disposed aerodynamic structure. The coating material
is supplied from a suitable source (noe shown) through a conduit 36
extending up through the aerodynamic structure, and an atomizing gas may
be supplied from a suitable source (not shown) through a conduit 38,
also extending up through the aerodynamic structure, for subsequent
mixing at the nozzle. The spray nozzle may also be pressure-operated
rather than gas-operated.
The upper surface of the gas shaping or aerodynamic structure
is centrally disposed within and extends generally horizontally across
the cross-section of the vertically disposed hollow column. In other
words, it has a cross~sectional 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 gases in such manner that the upwardly flowing
gases form a boundary layer that is directed awav from the wall surface
of the hollow column and that adheres to the upper surface of the gas
shaping or aerodynamic structure for flow across a portion thereof.
The upper surface of the aerodynamic structure may be flat
(not illustrated), but is preferably curved or approximately spherical
as illustrated. It may have a height (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-sectional diameter (D)
(See Fig 5) of the aerodynamic structure.
The surface below the greatest cross-sectional diameter may
also be flat tnot 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 surfa~e below is formed in
- 18 -
11~S4~94
the manner disclosed in the drawings.
The aerodynamic structure as disclosed and as described is
thus adapted to compress and accelerate the flowing gases near the
periphery of the hollow column and direct them toward the center 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.
The truncated hollow cone defines at its lower end a large
diameter somewhat smaller than the diameter of the vertically disposed
first hollow column, 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. The
particles are thus situated in an annular bed around the truncated
~; 20 hollow cone 14. The sloping outer '~211 surface of the truncated hollow
cone, 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
particles or pellets from the annular bed or storage zone inta the
coating, drying and deceleration zones and in return to the upper portion
of the annular bed. The atomizing spray is then turned on and appro-
priately adjusted in a suitable manner by controls (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 fro~ which the fluid emerges. Such
"orifice" in this instance is formed in the region therebetween the
,
-- 19 --
1 l~,r~
closest approach of the aerodynamic structure to the adjacent side wall
surfacer The gas flow emerging from the "orifice" region around the
aerodynamic structure is an annular flow which clings or adheres to the
surface of the aerodynamic structure. The flow, therefore, from any one
selected location around the "orifice" is opposed by the other flows so
that it is prevented from continuing further over the upper surface of
the aerodynamic structure by being forced upwardly away from the upper
surface at some point for flow into the truncated hollow cone. A
partial vacuum is formed in the region just above the upper surface of
the aerodynamic structure and at the lower edge of the truncated hollow
cone and this aids in ~he compression and focusing of the ising 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, and 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 ~anner,
the particles are pulled from the annular bed or storage zone into the
,;
upwardly flowing gas due to the aforementioned partial vacuum or reduced
pressure region that exists just above the screen adjacent the path of
upward flow as a consequence of this Coanda 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 described above
because there the horizontal shunting would extend not only toward the
aYis of the apparatus but also inefficiently toward the outer wall
surface 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
30 accelerating gas or air stream. As the particles pass through the lower
; central region or coating zone within the cone, they are contacted with
an atomized spray coating of material. This atomized spray emerges from
- 20 -
4~
the spray nozzle 34 because the liquid coating substance is either
forced through a single orifice designed to convert bulk liquids into
droplees, or the liquid and an atomizing air stream emerge simultaneously
from ~ets ad~acent to each other. In either case, the fine droplets of
coating material are in a flowable state, because the material is dissolved
or melted in the region immediately above the spray nozzle.
Further up the truncated hollow cone, the liquid nature of the
coating material, as deposited on the pellets or particles, changes to
solid by evaporative or other solidification processes. During the
transition from liquid to solid, the coated particles pass through a
stage when they are sticky or tacky and would agglomerate if they contacted
each other. This ccntact is 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 particles occurs at an increasing rate as they rise in the
cone. This acceleration causes an increasing vertical separation in
space between the particles and therefore reduces the tendency for the
particles to contact each other until the coating has become nontacky.
It is this region of the cone that is thus called the "drying zone".
When 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
gravity action to the annular bed where they gradually ~ove down, also
due to gravity, until they are pulled into the coating zone again. This
recycling or recirculation continues until, based on previous experiments,
30 a su~ficient coating has been applied.
The atomized spray is turned off, and the gas or air entraining
flow may be shut down or may be increased to drive the coated particles
- 21 -
into the uppermost region of the first hollow column, as for collection
in the manner illustrated in Fig. 4. Any other suitable manner of
unloading the finally coated particles may also be used.
A coating apparatus having the design characteristics essentially
as shown in Fig. 1, and having a diameter of eight (8) inches across the
lower end and four (4) inches across the upper end of the truncated hol-
low cone, is charged with twenty-five (25) pounds Gf generally spherical
pellets of animal feed supplement. The pellets are composed of 90%
methionine and 10% binders. The average diameter of the spherical pellets
is about 3 millimeter. About 250 s~andard cubic feet per minute of air
at about 7 p.s.i.g. is admitted to the plenum chamber 20. This air
causes a circulation of pellets through the truncated hollow cone 14,
and the height of the cone above the support screen 32 is adjusted to
obtain a pellet flow rate such that all the pellets in the annular storage
zone move through the cone about once every minute. A coating solution
is pumped through the spray no~zle 34 at the same time as 5 SCFM of
atomizing air at 40 p.s.i.g. is supplied to the nozzle. The pumping
rate is adjusted to pump one (1) pound of solution per minute. The
apparatus is operated for about 45 minutes. The product is a pellet
core coated with about a 2-mil layer of the polymer.
If the gases flowing upwardly around the aerodynamic structure
could be seen as a series of layers of molecules, merely for sake of
discussion, it is thought that there is an insignificant flow of molecules
or layer or so of molecules along the interior wall surface of the
second hollow column. By "insignificant" is meant that such layer or
layers of molecules will not perform any supporting function of the
particles in the annular bed.
Moving, therefore, radially inwardly from the interior wall
surface of the second hollow, the more significant layers of ~olecules
30 are caused to be~d toward the gas shaping or aerodynamic structure, the
innermost adhering to the surface of that structure as they pass upwardly
through the "orifice" region. This adherence of the molecules to the
- 22 -
surface of the aerodynamic structure may be favorably compared to the
"teapot efEect", which îs a low-speed form of the "Coanda effect". When
water is poured slowly from a glass, it tends to stick to the side of
the glass in the same way that tea sticks to the spout of a teapot.
High speed fluids behave similarly and adhere to a surface of suitable
shape.
As the rising molecules flow over the surface of the aerodynamic
structure after having passed the "orifice" region, previously mentioned,
at some point along the upper surface of the aerodynamic structure the
opposing character of the annular flow forces the molecules upwardly
aw2y from the upper surface as well as the adjace~t molecule layers. A
partial vacuum is created above the aerodynamic structure due to the
high speed upward flow of gases, causing an inward bending of the upwardly
moving molecules.
In the apparatus herein described, the particles move down in
the annular bed by gravity without any "dancing" occurring, and are
drawn into the upwardly flowing gases by the partial vacuum. Thus, any
attrition that might occur is greatly minimized, and the overall opera-
tion is much more efficient.
In reference to Fig. 2 in which a modification is disclosed, the
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 discussion.
Fig. 2 represents an embodiment wherein the size of the coating
apparatus 10' has been increased in order to handle larger batch loads
of particles for coating treatment. It has been found that it is more
practical to add an additional gas shaping or aerodynamic structure or
an annular airfoil 50 instead of increasing the size of the aerodynamic
structure 30'. In this manner, larger amounts of upwardly flowing gas
or air m~y be supplied undiminished or unobstructed by a larger aero-
dynamic structure, and the annular airfoil serves to supple~ent the com-
pression and focusing action on the upward gas flows so that substantially
- 23 -
all gas flows move through the truncated hollow cone 14'O
Additional or multiple gas shaping or annular airfoils (not
shown) also may be used for still larger coating apparatus. The exact
shape and placement of the airfoils are functions of a number of variables.
The most significant of the variables are size of the apparatus, size of
the particle to be coated, density of the particle, rate of gas or air
flow and the rate of recirculation of the particles through the coating
zone desired.
In a larger-scale coating apparatus, therefore, one or more
annularly shaped and placed gas shaping or aerodynamic structures or
airfoils, angled 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 r~dial struts in such manner as
to exert a minimum deflection of the upwardly flowing gases.
The annular aerodynamic structure is inwardly inclined in the
upward direction sa that its inclination lies 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
provides a surface on which the gas or air impinges for subsequent
shaping and direction upwardly nto the truncated hollow cone.
The vertical height of the annular structure may be about
10-50% of the perpendicular cross section diameter of the coating
apparatus.
In reference ~o Fig. 5, when the annular gas shaping structure
has the configuration of an airfoil having at least one curved surface
extending generally in the direction of gas flow, the overall angle of a
line described from a point Pl, on the lower rim of the airfoil to a
point, P2, on the upper rim in the vertical direction, or perpendicular
to a line which is tangent to the upper curved surface of the centrally
disposed aerodynamic structure, is from about 10 to about 45 inward
facing, as measured from the axis perpendicular to the diameter of the
- 24 -
11~4~
coating apparatus.
The cross-sectional configuration of an annular airfoil in a
plane described from the center of the cross-sectional area of the coating
apparatus to a point, Pl~ on the lower rim of the airfoil to a point,
P2, in the upper rim of the airfoil is teardrop, or similar to the cross-
sectional shape of a lifting aerodynamic shape, and having the thicker
cross section on the forward part with reference to the direction facing
the upwardly flowing gases. The thickest part is located about two~
fifths (2/5) to about one-half (1/2) of the height in the vertical
direction. In other words, the height (~) of the thickest part (T),
or HT is equal to about ~/5 H ~o about 1/2 H. The thickest cross
section (T) is from about one-sixth (1/6) to about two-fifths (2l5)
' of the height (H) of the airfoil; or T is equal to about 1/6 H to
., . ~
, about 2/5 H.
The size, placement and geometrical configuration of the
annular gas shaping structure are such, therefore, that the upwardly
flowing gases are deflected radially inwardly at an angle from about 10
to about 45 from a direction parallel to the original gas flow.
In reference to Fig. 3, the same reference numbers will be
used to identify similar elements previously described, except that they
will be double-primed to show that it is still another different embodi-
ment under discussion.
Fig. 3 represents an embodiment wherein the size of the coating
apparatus 10" has been increased to the same extent as that disclosed
in the Fig. 2 embodiment. The embodiment in Fig. 3 differs from the
embodiment in Fig. 2 in that the first and second hollow columns are
disclosed as being co-extensive in cross-sectional diameter. In other
words, the coating apparatus is disposed within a single hollow column.
It could also be of smaller size so that only one gas shaping or aero-
dynamic structure 30'' is employed as in Fig. 1, instead of a sizerequiring the annular airfoil 50''.
, The recycling or recirculation in this embodiment is necessarily
;
- 25 -
~, ~
,
4q~94
faster because the particles are not as readily restrained in the annular
bed region as they would be if there were an inwardly tapered base to
assist in such restraint. Proportionately smaller batch loads may be
used, therefore, since the recirculation of the particles is substantially
continuous with the particles spending very little time in the annular
bed. For this reason, an embodiment of this character is suitable for
special purposes, while the embodiments of Fig. 1 and Fig. 2 are deemed
to be of more general use.
In Fig. 4, this embodiment represents one manner of unloading
a coating apparatus, and was briefly mentioned above with respect to one
possible operation of the embodiment of Fig. 1.
Only the upper portion of a coating apparatus 60 i9 shown, and
it could be used for any of the previously described embodiments. A
conduit 62 is installed within the upper portion of the apparatus, as
shown, and a gas or air porous collection bag 64 may be installed at the
remote end of the conduit for collecting the finally coated particles
in the manner already heretofore described.
In any of the embodiments described above, the truncated hollow
cones may be adapted to be adjusted 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 desired
to suit gas or air flows, particle sizes and weights, coating material
consistencies and 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 arranged in cascaded manner to provide for a continuous coating
operation. The inlet for the particles in a cascaded arrangement may be
diposed above the annular storage of one apparatus and the particles
metered in predetermined manner into the annular storage bed, while the
30 outlet to the next coating appara~us may be disposed on the opposite
side of the annular storage bed and constitute a weir for outflow of
excess coated particles. The inlet may also be disposed for gravity
- 26 -
- - ~
11(~4~94
flow of particles to or into the annular storage bed. It may be desir-
able to provide for different coatings in different apparat~ls, or provide
supplemental coatings.
Multiple spray nozzles may also be employed, as desired, to
achieve different coatlng effects.
The exa~ples which follow are submitted for a better understanding
of the invention. While the examples are based on in vitro tests, the
in vitro experiments shown in the examples simulate conditions existing
in ruminants thereby permitting the study of coated pellets without the
; lO use of live animals. It has been ~etermined by actual in vivo tests
that the ~esting of pellets in ~he aqueous media used in the examples,
simulating the environmental conditions of the rumen and abomasum with
- respect to temperature, pH, etc., provide reliable data concerning the
protection offered by the coatings in the rumen, and releasability of
the coatings in the abomasum. ~Tutrients such as amino acids and proteins
which may be used in the core material are known to be beneficial to
ruminants when positioned in the intestinal tract downstream from the
rumen.
EX~L~ 1
L-Lysine monohydrochloride is soluble to the extent of about
70 g-tlOO g. of water at 25C., and the acidity of a saturated solution
~s pH 5.5 Pellets containing this material, when coated with such
sensitive polymers as cellulose propionate morpholinobutyrate or poly-
2-methyl-5-vinylpyridine, are not protected from dissolution in rumen environments
and, therefore, are not suitable for feed supplement directly available
for absorption by the ruminant animal. 364 Grams of finely powdered
l-lysine monohydrochloride i9 dry mixed with 91.25 g. basic magnesium
carbonate (hydromagnesite), 15 g. microcrystalline cellulose, and 5 g.
gum arabic. Next, 155 g. of water is added and mixing i9 continued to
obtain a plastic dough-like consistency. This dough-like material is
extruded through a multiorifice die having orifices of about 3 mm. in
diameter. Immediately on extrusion, the rod-shaped extrudate is chopped
- 27 -
~1~4~4
to about 3 mm. lengths using a knife rotating on the face of the die
plate. These particles are then dried to remove the water using an oven
heated to 60C. The dry pellets are coated with 50% of a copolymer of
80% 2-methyl-5-~inylpyridine and 20~ styrene, and 50% aluminum dioleate.
The pellets are stable in an environment of pH 5.5 for 24 hours, but
dissolve after about 2 hours in an environment of p~ about 3.5, indicating
their usefulness as a food for ruminants.
EXAMPLES 2-6
Example 1 is repeated using as core neutralizer 59 g. of mag-
nesium hydroxide, 80 g. of magnesium oxide, 100 g. of calcium carbonate,and 162 g. of monobasic aluminum dioleate, except the core material in
Example 6 is L-histidine. Similar results are obtained.
Unless otherwise specified, all parts, percentages, ratios, etc.,
are on a weight basis.
The fluid used to simulate environmental conditions of the
rumen (at pH 5.5) is prepared by mixing il.397 grams of sodium acetate
with 1.322 grams of acetic acid and diluting this mixture with
demineralized water to 1 liter.
The fluid used to simulate environmental conditions of the
20 abomasum (at pH 2.9) is prepared by mixing 7.505 grams glycine with
5.85 grams sodium chloride and diluting this mixture with demineralized
water to 1 liter. 31ght parts of this solution are mixed with 2 parts
of 0.1 normal hydrochloric acid for the test fluid.
The 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 rùminants, it is
considered that at least 60% and preferably at least 75~ of the active
ingredients of the core of the pellets to which ~his invention relates
30 should be stable in the rumen and release in the abomasum.
The invention has been described in detail with particular
reference to preferred embodimentq thereof, but it will be understood
- 28 -
~4~
that variations and modifications can be effected within the spirit and
scope of the invention.
. , .
~ 10
";
,,.
`:
- 29 _
