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Description  |
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FIELD OF THE INVENTION
The invention pertains to coated particles of fabric softener which are
included with detergent in the washing of fabrics. The particles survive
the wash and release softener to the fabrics in a heated laundry dryer.
BACKGROUND OF THE INVENTION
The advantages obtained from the application of fabric conditioning agents
(i.e., fabric softeners and/or antistatic agents) to laundered fabrics is
well-known. The present invention pertains to coated particulate
softener/antistatic compositions which survive the wash process and
release the active softening/antistatic agent to the laundered fabrics in
the dryer.
Fabric softening and antistatic benefits are a desirable part of the
laundry process. Softening and antistatic compounds are, in general,
quaternary ammonium compounds that are not compatible with anionic
surfactants. These compounds will be referred to hereinafter as fabric
softening compounds or fabric softeners, although it is to be understood
that they deliver both softening and antistatic benefits to fabrics. The
opposite electrical charge of the anionic surfactant used in most
detergents and the quaternary ammonium fabric softening compounds leads to
a mutual attraction which causes precipitation. This, in effect, removes
surfactant and fabric softener from solution and reduces the cleaning
capacity of the detergent while preventing effective fabric softener
deposition on the fabric.
One solution to this incompatibility problem is the separate addition of
the fabric softener during either the rinse cycle of the wash or while the
fabrics are in the dryer. This increases the inconvenience of using fabric
softeners because of the need to add them at a point in the laundering
process which is different from that at which the detergent is added.
Various other solutions for this problem of incompatibility between
detergent and softening compounds have been proposed in the art. U.S. Pat.
No. 3,936,537, Baskerville Jr., issued Feb. 3, 1976, and U.S. Pat. No.
4,095,946, Jones, issued June 20, 1978, teach the use of intimate mixtures
of organic dispersion inhibitors (e.g., stearyl alcohol and fatty sorbitan
esters) with solid fabric softener to improve the survival of the softener
in the presence of detergent in the washer so the softener can act on the
fabrics when it melts in the dryer. U.S. Pat. No. 4,234,627, Schilling,
issued Nov. 18, 1980, teaches microencapsulation of fabric softener. The
microcapsules survive the wash and adhere to the fabric surface. They are
then ruptured by subsequent tumbling of the fabric in the dryer, thereby
releasing softener to the fabrics. In spite of these developments, there
is a continuing need for methods and compositions which are suitable for
conveniently and effectively delivering fabric softeners to fabrics during
the home laundering process.
Accordingly, it is the object of the present invention to provide coated
fabric softener compositions wherein the coating will be insoluble in a
detergent solution but will release the softener to the fabrics at dryer
temperatures.
SUMMARY OF THE INVENTION
The present invention is directed to detergent-compatible, dryer-activated
fabric softening particles having diameters of from about 5 microns to
about 1,200 microns comprising an inner core of a fabric softener
composition comprising a cationic fabric softener compound, and an outer
coating comprised of water-insoluble material having a melting point above
about 35.degree. C.
The particles can be incorporated into laundry detergents.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to coated fabric softener particles which can
be added to the wash step of the fabric laundering process and which
release softener to fabrics in a laundry dryer. The invention also relates
to laundry detergent compositions containing said particles.
A. The Particles
The particles of the present invention comprise an inner core of a fabric
softener composition which comprises a cationic fabric softener, and an
outer coating which completely surrounds the core and comprises a
substantially water-insoluble material having a melting point above
35.degree. C., preferably above 50.degree. C. By "substantially
water-insoluble" herein is meant having a solubility in 35.degree. C.
water of less than about 50 ppm. The particles have diameters of from
about 5 microns to about 1,200 microns, preferably greater than about 500
microns, and most preferably greater than about 600 microns, with a number
average of from about 900 to about 1,000 microns. The particles typically
will be of a generally spherical shape, but can also have an irregular
shape. The particle sizes quoted herein refer to the largest dimension
(diameter or length) of the particle.
Typical cationic fabric softeners useful herein are quaternary ammonium
salts of the formula
[R.sub.1 R.sub.2 R.sub.3 R.sub.4 N].sup.+ Y.sup.-
wherein one or two of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 groups is an
organic radical containing a group selected from a C.sub.12 -C.sub.22
aliphatic radical or an alkylphenyl or alkylbenzyl radical having from 10
to 16 carbon atoms in the alkyl chain, the remaining groups being selected
from C.sub.1 -C.sub.4 alkyl, C.sub.2 -C.sub.4 hydroxyalkyl and cyclic
structures in which the nitrogen atom in the above formula forms part of
the ring, and Y constitutes an anionic radical such as halide, nitrate,
bisulfate, methylsulfate, ethylsulfate and phosphate, to balance the
cationic charge.
In the context of the above definition, the hydrophobic moiety (i.e., the
C.sub.12 -C.sub.22 aliphatic, C.sub.10 -C.sub.16 alkyl phenol or
alkylbenzyl radical) in the organic radical R.sub.1 or R.sub.2 may be
directly attached to the quaternary nitrogen atom or may be indirectly
attached thereto through an amide, ester, alkoxy, ether, or like grouping.
The quaternary ammonium compounds useful herein include both water-soluble
compounds and substantially water-insoluble compounds which are
dispersible in water. For example, imidazolinium compounds of the
structure
##STR1##
wherein R is a C.sub.16 to C.sub.22 alkyl group, possess appreciable water
solubility, but can be utilized in the present invention.
The quaternary ammonium softener compounds used in this invention can be
prepared in various ways well-known in the art and many such materials are
commercially available. The quaternaries are often made from alkyl halide
mixtures corresponding to the mixed alkyl chain lengths in fatty acids.
For example, the ditallowalkyl quaternaries are made from alkyl halides
having mixed C.sub.14 -C.sub.18 chain lengths. Such mixed di-long chain
quaternaries are useful herein and are preferred from a cost standpoint.
The anionic group which can be the counter-ion in the quaternary compounds
useful herein is typically a halide (e.g., chloride or bromide), nitrate,
bisulfate, ethylsulfate, or methylsulfate. The methylsulfate and chloride
ions are the preferred counter-ions from an availability standpoint; while
the methylsulfate anion is most preferred because of its minimization of
corrosive effects on the automatic clothes dryers in which it is used.
The following are representative examples of quaternary ammonium softening
compounds suitable for use in the present invention. All the quaternary
ammonium compounds listed can be included in the present invention, but
the compilation of suitable quaternary compounds hereinafter is only by
way of example and is not intended to be limiting of such compounds.
Dioctadecyldimethylammonium methylsulfate is an especially preferred
fabric softening compound for use herein, by virtue of its high
antistatic, as well as fabric softening activity;
ditallowalkyldimethylammonium methylsulfate is equally preferred because
of its ready availability and its good antistatic activity; other useful
di-long chain quaternary compounds are dicetyldimethylammonium chloride,
didocosyldimethylammonium chloride, didodecyldimethylammonium chloride,
ditallowalkyldimethylammonium bromide, dioleoyldimethylammonium
methylsulfate, ditallowalkyldiethylammonium chloride,
ditallowalkyldipropylammonium bromide, ditallowalkyldibutylammonium
fluoride, cetyldecylmethylethylammonium chloride,
bis-[ditallowalkyldimethylammonium] bisulfate,
tris-[ditallowalkyldimethylammonium] phosphate,
1-methyl-1-tallowamidoethyl-2-tallowimidazolinium methylsulfate, and the
like. Particularly preferred quaternary ammonium fabric softening
compounds are ditallowkyldimethylammonium chloride and
ditallowalkyldimethylammonium methylsulfate. The fabric softener core of
the particles of the invention comprises from about 70% to about 97% and
most preferably about 85% to about 97% of the particle. All percentages
herein are "by weight" unless otherwise indicated.
The core composition can consist entirely of cationic fabric softeners, and
will generally comprise at least 10%, usually 10% to 50% cationic fabric
softener. Optionally, and preferably, the core can contain additional
materials such as perfume, auxiliary fabric softening agents (e.g.,
smectite clay, fatty alcohols and fatty amine, such as ditallowmethyl
amine or 1-tallowamidoethyl-2-tallowimidazoline), soil release agents,
fabric brighteners, etc. Additional disclosure of materials which can be
applied to fabrics along with cationic fabric softening agents in a
laundry dryer and, therefore, can be part of the core composition of the
particles herein, are disclosed in U.S. Pat. Nos. 4,073,996, Bedenk et
al., issued Feb. 14, 1978; 4,237,155, Kardouche, issued Dec. 2, 1980; and
4,421,792, Rudy et al., issued Dec. 20, 1983, all incorporated herein by
reference. Preferred additional materials are the encapsulated fabric
conditioning perfume microcapsules of U.S. Pat. No. 4,234,627, Schilling,
issued Nov. 18, 1980, and British Pat. No. 1,549,432, both of which are
incorporated herein by reference. A particularly preferred process for
preparing such capsules is disclosed in U.S. Pat. No. 3,697,437, Fogle et
al., issued Oct. 10, 1972, incorporated herein by reference. Particle
sizes of from about 100 to about 200 microns are preferred.
The coating materials are substantially water-insoluble materials,
typically (but not necessarily) selected from waxy materials such as
paraffinic waxes, microcrystalline waxes, animal waxes, vegetable waxes,
saturated fatty acids and fatty alcohols having from 12 to 40 carbon atoms
in their alkyl chain, and fatty esters such as fatty acid triglycerides,
fatty acid esters of sorbitan and fatty acid esters of fatty alcohols, or
from substantially water-insoluble polymers. Typical specific suitable
waxy coating materials include lauric, myristic, palmitic, stearic,
arachidic and behenic acids, stearyl and behenyl alcohol, microcrystalline
wax, beeswax, spermaceti wax, candelilla wax, sorbitan tristearate,
sorbitan tetralaurate, tripalmitin, trimyristin and octacosane. A
preferred waxy material is stearyl alcohol.
Examples of water-insoluble polymeric materials which may be used for the
coating of the particles herein are [cellulose ethers such as ethyl,
propyl or butyl cellulose; cellulose esters such as cellulose acetate,
propionate, butyrate or acetate-butyrate]; ureaformaldehyde resins,
polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene,
polyacrylates, polymethacrylates, polymethyl-methacrylates and nylon. Such
materials and their equivalents are described in greater detail in any
conventional handbook of synthetic organic plastics, for example, in
Modern Plastics Encyclopaedia Volume, Vol. 62, No. 10A (for 1985-1986) at
pages 768-787, published by McGraw-Hill, New York, N.Y. (October 1985),
incorporated herein by reference. A preferred polymeric material is ethyl
cellulose. The polymeric coating materials can be plasticized with known
plasticizing agents such as phthalate, adipate and sebacate esters,
polyols (e.g., ethylene glycol), tricresyl phosphate, castor oil and
camphor.
The coating surrounds the cationic fabric softener core and is present in
an amount of from about 3% to about 30%, preferably from about 3% to about
15% by weight of the particle.
The coating material can comprise a mixture of waxy coating materials and
polymeric coating materials. In such mixtures the waxy coating material
will typically comprise from about 70% to about 90% of the mixture and the
polymeric material about 30% to about 10%.
Typically, the coating material will have a hardness which corresponds to a
needle penetration value of about 0.6 mm or less, and preferably less than
about 0.1 mm, as measured by ASTM Test D-1321, modified by using a 100 g
weight instead of a 50 g weight. The test is preformed at
25.degree.-27.degree. C. In the case of polymeric coating materials,
sample preparation is accomplished by dissolving the polymer in a volatile
solvent and then evaporating the solvent after the polymer solution has
been placed in the test container. For waxy coating materials, sample
preparation is done by melting the sample and then solidifying it in the
test container in the manner set forth in the ASTM method.
Penetration values of a number of suitable coating materials are shown in
the following table.
TABLE 1
______________________________________
Penetration Values of Representative Coating Materials
Penetraton
Material in mm
______________________________________
Stearyl alcohol 0.57
Ethyl cellulose 0.09
Cellulose acetate 0.00
Ethyl cellulose + 10% dibutyl sebacate
0.00
70% Stearyl alcohol + 30% C.sub.30 alcohol
0.32
90% Stearyl alcohol + 10% Elvax-4310.sup.1
0.12
90% Stearyl alcohol + 10% BE-Square-195.sup.2
0.40
______________________________________
.sup.1 Terpolymer of ethylene, vinyl acetate and acid from DuPont
.sup.2 Microcrystalline wax from Petrolite, Speciality Polymers Group
The function of the coating which surrounds the fabric softener is to
prevent the softener from becoming dissolved and/or dispersed in the wash
water when the particles are present during the wash step of a laundry
process, and thereby prevent interaction between the fabric softener and
the detergent. During the washing and rinsing of the fabrics, a
substantial amount of the particles adhere to, or become entrapped within
folds of the fabrics. When the fabrics are dried in a heated automatic
clothes dryer (typically at temperatures of about 65.degree. to 85.degree.
C.), the coating and the fabric softener core composition melt, thereby
permitting the softener to spread throughout the fabric load and soften
the fabrics.
If the particles are incorporated into a granular detergent composition, it
is preferred that the particle size of the softener particles be similar
to the particle size of the detergent granule in order to minimize
segregation. This will typically be in the range of from about 500 to
about 1000 microns. Softener particles which are smaller in size than the
detergent granules can be agglomerated to form larger particles to match
the particle size of the detergent granules into which they will be
incorporated. The agglomeration can be accomplished by using water-soluble
or dispersible materials such as polyvinyl alcohol, sodium carboxymethyl
cellulose, gelatin and polyoxyethylene waxes. The agglomerates
disintegrate when the detergent composition is added to water. Methods and
agglomerating agents for agglomeration of fabric softener particles are
described in U.S. Pat. No. 4,141,841, McDanald, issued Feb. 27, 1979,
incorporated by reference herein.
B. Preparation of Particles
In preparing the softener particles of the invention, the solid fabric
softener composition which is to be the core of the particles is formed
into particles having a size of from about 4.5 to about 1100 microns. This
can be accomplished, for example, by milling the solid softener
composition or by melting the composition and spraying it through
appropriate sized nozzles into an atmosphere having a temperature below
the melting point of the softener, thereby forming the softener
composition into solid particles.
The particles of softener composition can then be coated with coating
material which is either melted or dissolved in a volatile solvent. The
coating is done at a temperature which is below the melting point of the
softener composition, and the coated particles are then cooled (or the
solvent is evaporated) to solidify the coating. The coating is typically
applied in a fluidized bed type apparatus. A suitable type of apparatus is
that described in U.S. Pat. No. 3,196,827, Wurster et al., issued July 27,
1965, incorporated by reference herein. In this apparatus, solid softener
core particles are suspended on an air stream which carries them in a
smooth cyclic flow past the coating nozzle, which sprays them with fluid
coating material. Air atomizes and expels the coating fluid through the
coating nozzle. The atomized coating fluid covers the surfaces of the core
particles. The coated particles are lifted on the air stream and the fluid
coating solidifies on the surface of the particles as the air stream lifts
them away from the nozzle. The particles then settle out of the air stream
and begin another cycle which takes them past the nozzle again. The
process is repeated until the desired amount of coating has been deposited
on the particles. The amount of coating applied to the softener core
particles is typically from about 3% to about 30%, preferably about 3% to
about 15% by weight of total particle (i.e., core plus coating).
Alternatively, other types of encapsulating processes such as described in
an article by Nack entitled "Microencapsulation Techniques, Applications
and Problems," J. Soc. Cos. Chem., Vol. 21, Pages 85-98 (Feb. 4, 1970),
incorporated herein by reference, can be used. When perfume microcapsules
are incorporated, the processes disclosed in U.S. Pat. No. 4,234,627,
supra, incorporated herein by reference, can be used.
If it is desired to aggomerate the softener particles, this can be
accomplished in the following manner. The softener particles are fed to a
highly efficient mixer (e.g., Schugi Flexomix Model 160,335 or 400 from
Schugi Process Engineers U.S.A., 41-T Tamarack Circle, Skillman, N.J.
08558), or a pan agglomerator. Aqueous solution or dispersion of
agglomerating agent is sprayed onto the moving particles causing them to
stick to each other. The water is evaporated and the dried agglomerated
particles are sized by sieving. Suitable agglomerating agents include
dextrin starches, Pluronic Polyols (copolymers of ethylene oxide and/or
propylene oxide with either ethylene glycol or propylene glycol) and
hydratable salts such as sodium tripolyphosphate or sodium sulfate.
The type of apparatus described in U.S. Pat. No. 3,196,827 (Wurster et
al.), cited supra, can also be used for agglomerating particles.
C. Detergent Compositions
The particles of the present invention are preferably formulated into
detergent compositions. Such compositions typically comprise detersive
surfactants and detergency builders and, optionally, additional
ingredients such as bleaches, enzymes, fabric brighteners and the like.
The particles are present in the detergent composition at a level
sufficient to provide from about 0.5% to about 10%, and preferably from
about 1% to about 5% of quaternary ammonium fabric softener in the
detergent composition. The remainder of the detergent composition will
comprise from about 1% to about 50%, preferably from about 10% to about
25% detersive surfactant, and from about 15% to about 60%, preferably from
about 20% to about 45% of a detergency builder, and, if desired, other
optional laundry detergent components.
1. The Surfactant
Surfactants useful in the detergent compositions herein include well-known
synthetic anionic, nonionic, amphoteric and zwitterionic surfactants.
Typical of these are the alky benzene sulfonates, alkyl- and alkylether
sulfates, paraffin sulfonates, olefin sulfonates, alkoxylated (especially
ethoxylated) alcohols and alkyl phenols, amine oxides, alpha-sulfonates of
fatty acids and of fatty acid esters, alkyl betaines, and the like, which
are well known from the detergency art. In general, such detersive
surfactants contain an alkyl group in the C.sub.9 -C.sub.18 range. The
anionic detersive surfactants can be used in the form of their sodium,
potassium or triethanolammonium salts; the nonionics generally contain
from about 5 to about 17 ethylene oxide groups. C.sub.11 -C.sub.16 alkyl
benzene sulfonates, C.sub.12 -C.sub.18 paraffin-sulfonates and alkyl
sulfates are especially preferred in the compositions of the present type.
A detailed listing of suitable surfactants for the detergent compositions
herein can be found in U.S. Pat. No. 3,936,537, Baskerville, issued Feb.
3, 1976, incorporated by reference herein. Commercial sources of such
surfactants can be found in McCutcheon's EMULSIFIERS AND DETERGENTS, North
American Edition, 1984, McCutcheon Division, MC Publishing Company, also
incorporated herein be reference.
2. Detergency Builders
Useful detergency builders for the detergent compositions herein include
any of the conventional inorganic and organic water-soluble builder salts,
as well as various water-insoluble and so-called "seeded" builders.
Nonlimiting examples of suitable water-soluble, inorganic alkaline
detergent builder salts include the alkali metal carbonates, borates,
phosphates, polyphosphates, tripolyphosphates, bicarbonates, silicates,
and sulfates. Specific examples of such salts include the sodium and
potassium tetraborates, bicarbonates, carbonates, tripolyphosphates,
pyrophosphates, and hexametaphosphates.
Examples of suitable organic alkaline detergency builder salts are: (1)
water-soluble amino polyacetates, e.g., sodium and potassium
ethylenediaminetetraacetates, nitrilotriacetates, and
N-(2-hydroxyethyl)nitrilodiacetates; (2) water-soluble salts of phytic
acid, e.g., sodium and potassium phytates; (3) water-soluble
polyphosphonates, including sodium, potassium and lithium salts of
ethene-1-hydroxy-1,1-diphosphonic acid, sodium, potassium, and lithium
salts of methylenediphosphonic acid and the like.
Seeded builders include such materials as sodium carbonate or sodium
silicate, seeded with calcium carbonate or barium sulfate.
A detailed listing of suitable detergency builders can be found in U.S.
Pat. No. 3,936,537, supra, incorporated herein by reference.
3. Optional Detergent Ingredients
Optional detergent composition components include enzymes (e.g., proteases
and amylases), halogen bleaches (e.g., sodium and potassium
dichloroisocyanurates), peroxyacid bleaches (e.g.,
diperoxydodecane-1,12-dioic acid), inorganic percompound bleaches (e.g.,
sodium perborate), activators for perborate (e.g.,
tetraacetylethylenediamine and sodium nonanoyloxybenzene sulfonate), soil
release agents (e.g., methylcellulose) soil suspending agents (e.g.,
sodium carboxymethylcellulose) and fabric brighteners.
C. Pouched Compositions
When fabric softener particles of the invention are added to the wash step
of a laundering process, it is inevitable that some of the particles will
not adhere to or become trapped in the folds of the fabrics and will,
therefore, be lost in the discarded wash solution or rinse water. In order
to avoid such loss, the particles can be added to the wash solution in a
sealed, porous water-insoluble pouch such as the type described in U.S.
Pat. No. 4,223,029, Mahler et al., issued Sept. 16, 1980, incorporated by
reference herein. Detergent granules can be included in the pouch with the
softener particles. When the pouch is placed in water in the wash step of
the laundering process, the detergent dissolves, but the softener
particles remain in the pouch. The pouch remains with the fabrics through
the wash and rinse. When the pouch is tumbled with the fabrics in the
dryer, the softener particles release the softener, which melts onto the
pouch material and is transferred from the pouch material to the fabrics
as the pouch comes into contact with the fabrics during the drying cycle.
Preferred pouch structures are multi-pouch porous sheet structures such as
described in U.S. patent application Ser. No. 675,804, Bedenk et al.,
filed Nov. 28, 1984, now U.S. Pat. No. 4,638,907, Bedenk/Harden, issued
Jan. 27, 1987; and U.S. Pat. No. 4,259,383, Eggensperger et al., issued
Mar. 31, 1981, both incorporated herein by reference. In a single pouch
structure, the particles tend to collect in a relatively small area of the
structure, whereas in a multi-pouch sheet structure the softener particles
are distributed over a larger area of the structure thereby facilitating
more even transfer of softener to fabrics in the dryer.
Suitable pouch materials include, paper, nonwoven synthetics such as
spunbonded and wet laid polyester, and porous formed film plastic sheet
material.
In a further improvement of the multi-pouch type of structure, the
individual pouches have a water-insoluble baffling means which provides
some standoff between the interior major surfaces of the pouches while the
multi-pouch sheet is being tumbled in the clothes dryer. The standoff
prevents the interior major surfaces of each pouch from coming into
intimate contact with each other during the drying cycle, thereby reducing
the tendency of the molten softener to be squeezed out of the pouch during
the drying cycle, which can cause fabric staining. It is preferred that
the molten softener be permitted to gradually wick through the substrate
and thereby gradually transfer to the tumbling fabrics. The baffling can
be produced, for example, by printing a cross hatched glue pattern on one
of the interior surfaces of the pouch material or by including a layer of
polymeric net material between the interior major surfaces of the pouches.
The invention will be illustrated by the following examples.
EXAMPLE I
Fabric softener core particles are prepared according to the following
formula:
______________________________________
Ingredient Wt. %
______________________________________
Ditallowdimethylammonium
42.4
methylsulfate (DTDMAMS)
Sorbitan monostearate
21.3
Cetyl alcohol 21.3
Bentonite clay 12.0
Perfume 3.0
Total 100.0
______________________________________
The DTDMAMS is heated in a reaction vessel at 71.degree. C. under vacuum
(Ca. 710 mm Hg) for 4 hours to remove residual moisture and/or
isopropanol. The cetyl alcohol and sorbitan monostearate are then added,
and the molten "triblend" is mixed for one hour at about 71.degree. C.
The triblend is transferred into a PVM 40 Ross mixer (Charles Ross & Sons
Company, Hauppauge, New York 11788). The temperature of the triblend is
then raised to 79.degree. C.-85.degree. C. under vacuum (about 330-430 mm
Hg). When the temperature has stabilized in this range, the Ross' anchor
and disperser are turned on and the clay is added. The mixture is blended
for 5 minutes and then sheared with the Ross' colloid mixer for 20
minutes. The perfume is then added and the mixture is blended for 5
minutes with the anchor, disperser and colloid mill still on. The softener
composition is then poured into trays and cooled overnight at about
4.degree. C.
The solid softener core composition is then converted to particles by
milling in a Fitzmill, Model DA506 (The Fitzpatrick Company, Elmhurst,
Ill. 60126) at 4740 rpm's through a 4 mesh screen. The particles are then
sized through 12 on 30 (U.S. Standard screens, 1.7-0.6 mm particle size).
The particles are then coated with a hot melt of fatty alcohol-based
coating. The coating is a mixture of 90% stearyl alcohol and 10%
Elvax-4310, a terpolymer of ethylene, vinyl acetate and acid from E. I. du
Pont de Nemours & Co., Polymer Products Dept., 1007 Market St.,
Wilmington, Del. 19898. The coating is applied in an 18 Inch Wurster
coater (Coating Place, Inc., P.O. Box 248, Verona, Wis. 53593). A detailed
description of this type of equipment can be found in U.S. Pat. No.
3,196,827, supra, incorporated by reference herein.
Briefly, the Wurster Coater consists of an apparatus that is capable of
suspending the softener core particles on a rapidly moving warm air
stream. Encapsulation is accomplished by passing the softener particles
through a zone of finely atomized droplets of coating. As the particles
move up and away from the coating nozzle, the coating begins to solidify
as the particles cool. When the particles can no longer be fluidized by
the air stream, they move down in the opposite direction of the fluidizing
air. The coated particles then reenter the coating zone and are recycled
until the desired amount of coating is applied. The coating cycle takes
place within a single chamber which preferably has a partition to separate
the particles moving up through the coating zone from those moving down
through the cooling zone.
The following conditions are used to apply a hot melt coating:
______________________________________
Stearyl Alcohol/Elvax
79.degree. C.
Temperature
Fluidizing Air 15.8 Cu.M/min. at 40.5.degree. C.
Atomizing Air Volume
0.25 Cu.M/min.
Atomizing Air Rate
4218 g/sq.cm.
Inlet Air Temperature
20.degree. C.-38.degree. C.
Outlet Air Temperature
20.degree. C.-38.degree. C.
Pump Rate 0.2 Kg/min.
Nozzle Size CPI-18-A74*
Partition Size 216 mm .times. 267 mm
Partition Gap 19 mm
Run Time 22 min.
______________________________________
*Available from Coating Place, Inc.
The amount of fatty alcohol coating applied to the softener particles is
about 15% by weight of the total coated particle. After the coating
process is complete the particles are resized through 12 on 20 mesh and
are then ready for use "as is" or for blending into detergent granules.
EXAMPLE II
Softener core particles prepared as in Example I are coated with ethyl
cellulose based coating instead of fatty alcohol. The coating is applied
by spraying a 10% solids solution in methanol of 9 parts ethyl cellulose
and 1 part dibutyl sebacate. The coating is applied in an 18 Inch Wurster
coater as described in Example I. The ethyl cellulose used is Ethocel Std.
4, (Dow Chemical Co., Midland, Michigan 48640) which has an Ubbelhhode
viscosity of 3.0-5.5, measured at 25.degree. C. as a 5% solution in 80%
toluene/20% ethanol.
The following conditions are used to apply a solvent based coating:
______________________________________
Fluidizing Air 15.8 Cu.M/min. at 40.5.degree. C.
Atomizing Air Volume
0.37 Cu.M/min.
Atomizing Air Rate
5624 g/sq.cm.
Inlet Air Temperature
38.degree. C.-43.degree. C.
Outlet Air Temperature
30.degree. C.-32.degree. C.
Pump Rate 0.2 Kg/min.
Nozzle Size CPI-18-A74*
Partition Size 216 mm .times. 267 mm
Partition Gap 19 mm
Run Time 120 min.
______________________________________
*Available from Coating Place, Inc.
The amount of ethyl cellulose/dibutyl sebacate solids coated onto the
particles is about 5% by weight of the total coated particle weight. When
the coating is completed, the softener particles are resized through 12 on
30 Mesh U.S. Standard screens and are then ready for use "as is" or for
blending into detergent granules.
EXAMPLE III
A fabric softener core particle containing perfume capsules is prepared
according to the following formula:
______________________________________
Ingredient Wt. %
______________________________________
Perfume 89.20
Gelatin 275 Bloom 8.80
Glutaraldehyde 1.12
Polyphosphate 0.88
Total 100.00
______________________________________
The perfume capsules are prepared using a complex coacervation process as
described in U.S. Pat. No. 3,697,437, supra. Briefly, the process is as
follows.
To a vessel equipped for stirring and heating, the following components are
each preheated to 52.degree. C. and combined: 1000 mls of deionized water,
1000 mls of a 10% by weight solution of gelatin in deionized water (Kind &
Knox Type A gelatin, 275 Bloom) and 1000 mls of a water-insoluble perfume.
The solution is then emulsified via agitation at 52.degree. C. The
agitation speed is adjusted such that the mean particle size of the
droplets is between 100 and 200 | | |
