Note: Descriptions are shown in the official language in which they were submitted.
CA 02368600 2001-09-21
WO 00/63341 PCT/US00110386
1
PROCESS FOR MAKING NON-STAINING COLORED PARTICLES FOR IMPROVING
AESTHETICS OF A LIOUID AUTOMATIC DISHWASHING DETERGENT PRODUCT THE
PARTICLES, AND A COMPOSITION
10
TECHNICAL FIELD
The present invention generally relates to liquid automatic dishwashing
detergent
compositions. More particularly, the invention relates to a process for making
colored particles
that can be incorporated into a bleach-containing or non-bleach-containing
liquid automatic
dishwashing detergent composition for improving the aesthetics of the liquid
composition
wherein the colored particles do not stain the plastic surfaces of dishware or
an automatic
dishwasher.
BACKGROUND OF THE INVENTION
Consumers of liquid ADW products have a preference for such products having a
certain
color or appearance. The addition of solid particles suspended into a liquid
ADW composition
can improve the aesthetics of the product by simply improving the physical
appearance of the
product. This is particularly true if the particles are colored and their
color is matched effectively
to the base color of the liquid ADW composition.
Previously used particles in liquid ADW products have had a major disadvantage
of
contributing negatively to unwanted filming, particularly on glass, stainless
steel and plastic
surfaces. This is because the previously used particles have been coated with
water-insoluble
coatings, such as waxes, which melt and are released into the wash solution
due to the high
temperature encountered during the automatic dishwashing process.
Further, in the arena of bleach containing liquid ADWs, the particles cannot
be colored by
simply using a dye, because during storage of the liquid ADW product, the dye
gets bleached.
Thus, the formulators have to use bleach-safe pigments to impart an
aesthetically pleasing color.
Before this invention, the incorporation of pigments posed a major problem:
the color of the
CA 02368600 2001-09-21
WO 00/63341 PCT/US00/10386
pigment is found to detrimentally stain plastic surfaces, such as plastic
dishware and the internal
plastic surfaces of a dishwasher.
It has been desirable to have a process by which colored pigment based
particles can be
made for incorporation in bleach-containing or non-bleach-containing liquid
ADW product, such
that the particles are non-staining. It has also been desirable that the solid
particles do not
dissolve in the liquid ADW product, but dissolve rapidly in the wash solution
during automatic
dishwashing. It has been desirable to have a liquid ADW product having solid
particles that do
not cause a significant amount of unwanted filming on glass, stainless steel
and plastic.
The inventors of the present invention have discovered a process of coating
the particles
with a pigment in a manner such that the particles are non-staining. This
invention is not limited
to just bleach-containing liquid ADWs and is also applicable to non-bleach-
containing liquid
ADWs that are incorporated with prills or particles colored with pigments. The
present invention
is thus directed to overcome one or more of the problems as set forth before.
SUMMARY OF THE INVENTION
1 S The invention meets the needs above by providing a process for forming a
non-staining
colored composite particle suitable for incorporation in a bleach-containing
or non-bleach-
containing liquid detergent composition, a non-staining colored composite
particle and a liquid
dishwashing detergent composition.
In one aspect of the present invention, the process includes the steps of
forming a colored
liquid dispersion of pigment particles in a first liquid medium. The size of
the pigment particles
in the colored liquid dispersion is no greater than about S Vim. The process
includes the step of
mixing the colored liquid dispersion with a polymeric material and a second
liquid medium to
form a sprayable colored polymeric material. The polymeric material being
selected from the
group consisting of alkyl cellulose ethers and polyvinyl alcohol. The process
also includes the
step of spraying the colored polymeric material on a composite particle and
forming a colored
polymeric coating on the composite particle.
In another aspect of the present invention, a non-staining colored composite
particle
suitable for incorporation in a bleach-containing liquid detergent composition
is disclosed. The
particle is made by the process as set forth above.
In yet another aspect of the present invention, a liquid automatic dishwashing
detergent
product is disclosed. The product includes a liquid dishwashing detergent
composition
containing chlorine bleach, and non-staining colored composite particles. The
particles are made
by the process as set forth above.
CA 02368600 2001-09-21
WO 00/63341 PCT/US00/10386
-3-
DETAILED DESCRIPTION OF THE INVENTION
In the preferred embodiment of the present invention, the process includes the
steps of
forming a colored liquid dispersion of pigment particles in a first liquid
medium.
Pigment processine
The size of the pigment particles in the colored liquid dispersion is
desirably no greater
than about 5 Vim, preferably no greater than about 1 Vim, more preferably no
greater than about
0.1 Vim, and most preferably no greater than about 0.01 Vim. It has been
surprisingly discovered
that when the pigment particle size in the pigment-liquid dispersion is
maintained within the
above size limitations, the resultant pigment, when deposited on a particle as
a part of the
sprayable polymeric slurry, is essentially non-staining. i.e., its color does
not transfer onto plastic
surfaces. The selection of the pigment particle size is the key to the present
invention. One
skilled in the art can apply other means for achieving a pigment particle size
in the size limitation
as disclosed above.
In the preferred embodiment, the first liquid medium is preferably water.
Optionally, a
minor amount of a nonionic surfactant is added to the water to improve the
dispersion of the
pigment. Typically, this surfactant is added in an amount no greater than
about 10% by weight.
In the preferred embodiment, the process includes the step of maintaining the
amount of
surfactants used in the bleach-containing liquid detergent composition at a
preselected value such
that when the bleach-containing liquid detergent composition is diluted in a
wash solution, the
amount of surfactant delivered in the wash solution is less than critical
micelle concentration.
The term "critical micelle concentration" is well known to those skilled in
the art and need not be
explained any further for purposes of brevity.
Polymeric coating
In the preferred embodiment, the colored polymeric coating is insoluble in the
liquid
automatic dishwashing detergent composition but soluble in automatic
dishwashing wash
solution. The coating is prepared from materials which are insoluble in the
liquid automatic
dishwashing detergent composition but soluble in automatic dishwashing wash
solution. The
coating is prepared from materials selected from the group consisting of alkyl
cellulose ethers
and polyvinyl alcohol. Alternatively, the coating is prepared from alginate.
Desirably, the alkyl
cellulose ethers are selected from one of methyl cellulose and hydroxypropyl
methyl cellulose
(HPMC). Preferably, the coating is prepared from methyl cellulose having a
number average
molecular weight desirably in a range of from about 5000 to about 100,000,
more preferably from
about 10,000 to about 20,000, and most preferably, about 14,000. The preferred
methyl cellulose
CA 02368600 2004-10-12
is one sold under the trade name MethocelT~' A l SLV. and manufactured by Dow
Chemicals
Alternatively, the polymeric coating is polyvinyl alcohol (PVA) having a
molecular weight,
desirably in a range of from about 5000 to about 100,000, and preferably from
about 13,000 to
about 23,000. The preferred PVA is from about 87% to about 89% hydrolyzed,
such as a
commercially available product having a trade name AirvolT"' 205. Further. the
particles are
insoluble in the liquid automatic dishwashing detergent composition and only
soluble in the wash
solution during automatic dishwashing.
Process for snraving colored polymeric coatine on particles
The process by which the colored polymeric coating is prepared and deposited
upon the
particle is critical in order for the particles to remain undissolved in the
liquid automatic
dishwashing detergent composition and only become soluble in the wash solution
during
automatic dishwashing. It is desirable that the panicles dispersed in the
liquid ADW
compositions do not break up or dissolve in the composition. It is also
desirable that this be
achieved without depositing an unduly thick coating of a polymeric material on
the panicle. It
has been surprisingly discovered that when the polymeric material, such as
methyl cellulose is
sufficiently hydrated before spraying on the particle or prill, the polymer
coated particle or prill
remains stable, unbroken and undissolved in the liquid ADW composition. This
hydration is
achieved by forming a sprayable aqueous solution of the polymer (alkyl
cellulose ether and/or
polyvinyl alcohol) having a polymer concentration desirably in a range of from
about 1 % to about
30% by weight, preferably in a range of about 3°J° to about 20
%, more preferably in a range of
about 3% to about 10 %, and most preferably, about 5%. Further, the
temperature of aqueous
solution of the polymer is desirably maintained within a range of from about
30 °C to about 40 °C
while spraying the polymer solution on the particle, and preferably in a range
of from about 32 °C
to about 38 °C, and most preferably at a temperature of about 35
°C. It has been surprisingly
found that by using a combination of the above process steps, i.e., the
polymer solution being in a
range of from about 1 % to 30% by weight, and the spray temperature being in a
range of from
about 30 °C to about 40 °C, that a very stable, unbroken,
continuous coating is formed on the
panicle or prill which is undissolved in the liquid ADW composition but
soluble in the wash
solution, while at the same time, requiring only about 5% polymer by weight of
the panicle. In
the preferred embodiment, the coating is desirably present in an amount in a
range of from about
1 % to about 25% by weight of the particle, preferably from about 4% to about
10% by weight of
the particle, and most preferably, about 5°.o by weight of the panicle.
The reduced coating weight
levels are desirable so that the least effective coating amount is used in
order to accomplish the
CA 02368600 2004-10-12
-5-
objective to having a protective coating without unnecessary polymer that
might detrimentally
contribute to unwanted residue deposition in the washing machine.
Color
In one embodiment, the panicles are colored and the automatic dishwashing
liquid
detergent composition is clear or translucent, so as to make the liquid
automatic dishwashing
product aesthetically pleasing. In another embodiment. the panicles and the
liquid automatic
dishwashing detergent composition are both colored and the color of the
particles is matched to
the base color of the liquid composition. In one embodiment, the paniclcs have
a dark green
color whereas the liquid composition has a light green color. Other preferred
color combinations
for the polymeric coating on the particles and the liquid automatic
dishwashing composition are:
blue:blue, blue:white, green:green, green:white and green:yellow,
respectively.
Desirably, the particles comprise from about 0.1 % to about 5.0% by weight of
the liquid
composition, and preferably, from about 0.2% to about 1.0% by weight of the
liquid composition.
In another embodiment of the present invention, a non-staining colored
composite
particle suitable for incorporation in a bleach-containing liquid detergent
composition is
disclosed. The panicle is made by the process as set forth above.
Particles
The particles can be formed from various materials that do not cause any
detrimental
affect upon the performance of the liquid detergent. Preferably, the particles
are in the form of
prills. The prills typically have a core which is coated with a polymeric
coating as described
before. The core can be made from sucrose, as an example. The method of
forming prills is well
known to those skilled in the art and is disclosed in the literature, such as
for example, in U.S.
Patent No. 4,965,012,.
The particles can be of various sizes and shapes, such as spherical, oval,
cylindrical or
polygonal and desirably have a particle size in a range of from about 200 Elm
to about 5000 E<m,
preferably, from about 400 Elm to about 2000 Elm, and most prefer ably, from
about 500 Elm to
about 850 E<m.
In yet another embodiment of the present invention, a liquid automatic
dishwashing
detergent product is disclosed. The product includes a liquid dishwashing
detergent composition
containing chlorine bleach, and non-staining colored composite particles, The
particles are made
by the process as set forth above.
Li4uid automatic dishwashin~~composition components
'The liquid automatic dishwashing detergent product is highly viscous in a
aui~scent state
and has a relatively high yield stress values, when subjected to sheaf
stresses, however, such as
CA 02368600 2004-10-12
-6-
being shaken in a container or squeezed through an orifice, the product
quickly fluidizes and
upon cessation of the applied shear stress, quickly revens to a high viscosity
state. The above
liquid automatic dishwashing detergent product is preferably low foaming,
readily soluble in the
washing medium and most effective at pH values best conducive to improved
cleaning
performance, such as in a range of desirably from about pH 7.0 to about pH
13.0, and preferably
from about pH 8.0 to about pH 12Ø
The physical stability of the liquid product may be improved and the thickness
of the
liquid product may be altered by the addition of a cross linking polyacrylate
thickener to the
liquid detergent product as a thixotropic thickener.
PH adj,ustin~ components
i
The pH adjusting components are desirably selected from sodium or potassium
carbonate
or sesquicarbonate, sodium or potassium silicate, citric acid, sodium or
potassium bicarbonate,
sodium or potassium borate, sodium or potassium hydroxide, and mixtures
thereof. NaOH or
KOH are the preferred ingredients for increasing the pH to within the above
ranges. Other
IS preferred pH adjusting ingredients are sodium carbonate, potassium
carbonate, and mixtures
thereof.
Low FoamingSurfactant
Chlorine bleach stable low foaming surfactants are preferred and such
surfactants are
present in a range of from about 0.1 % to about 10% by weight of the liquid
composition. Such
surfactants are generally known to one skilled in the art and need not be
elaborated here, for
purposes ofbrevity. One example of such a surfactant is an anionic surfactant
commercially
available under the trade name - DowfaxTM
Other ingredients
?he liquid automatic dishwashing detergent composition optionally also
contains from
about 0.5% to about 20°!° of a dispersant polymer selected from
the group consisting of
polyacrylates and polyacrylate copolymers, and from about 0.1% to about 5% of
a chlorine
bleach stable foam suppressant. Such foam suppressants are well known to those
skilled in the
ari.
To exemplify various embodiments of the present invention, Sample A of the
liquid
automatic dishwashing detergent product composition is formulated using the
below named
ingredients, as set forth in Example A.
EXAMPLE A
)~redient (weight % activel A
CA 02368600 2001-09-21
WO 00/63341 PCT/US00/10386
_7_
Sodium Tripolyphosphate 17.5
Potassium Tripolyphosphate---
Sodium Silicate 6.0
Potassium hydroxide 3.6
Sodium hydroxide 2.0
Polyacrylate polymer 1.0
Nitric Acid 0.012
Perfume 0.03
Nonionic surfactant ---
Sodium Benzoate 0.75
Sodium hypochlorite 1.15
Polyacrylate polymer thickener1.5
Dye solution ---
Solid Prill 0.5
Water Bal.
TOTAL 100:0
In the above composition, the non-staining colored particles having a
spherical shape, and a
diameter of about 750 Vim, are formed from a sucrose core coated with a
polymeric coating
formed from methyl cellulose (Methocel A15LV), and having a bluish-green
color. The bluish-
green color is imparted by adding a pigment into the methyl cellulose coating
before spraying it
on the particle according to the process of the present invention. The
particles comprise about
0.1 % to about 5% by weight of the liquid composition. The optimum methyl
cellulose coating is
about 5% by weight of the particle. The coating is sprayed on the sucrose core
particle by
spraying a 5% by weight aqueous solution of methyl cellulose with pigment. The
aqueous
solution temperature being carefully maintained at about 35 °C. The
size of the pigment particles
in the aqueous solution is no greater than about 1 Vim.
The resultant particles are insoluble in the liquid composition but are
soluble in the wash solution
during automatic dishwashing. The resultant colored particles are also non-
staining to plastic
surfaces.
Accordingly, having thus described the invention in detail, it will be obvious
to those
skilled in the art that various changes may be made without departing from the
scope of the
invention and the invention is not to be considered limited to what is
described in the
specification.
