Note: Descriptions are shown in the official language in which they were submitted.
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Wash C:ycle Unit Dose Softener
Field of the Invention
This invention relates to wash cycle unit dose laundry compositions for
softening or
' conditioning fabrics. More particularly, this invention relates to unit dose
fabric softening
compositions which are compacted granular compositions suitable for use in the
wash cycle
of an automatic washing machine.
. Background of the Invention
Detergent compositions manufactured in the form of compacted detergent powder
are
known in the art. U.S. 5,225,100, for example, describes a tablet of compacted
powder
comprising an anionic detergent compound which will adequately disperse in the
wash water.
Although detergent compositions in the form of compacted granular tablets of
various
shapes have received much attention in the patent literature, the use of such
tablets to provide
a unit dose fabric softener which will soften or condition fabrics in the wash
cycle without
impairing detergency or otherwise compromise the cleaning benefits provided by
the
detergent composition is not known.
Another possible option for providing a unit dose softener apart from the wash
cycle is
to introduce the softening ingredients directly into the rinse cycle. But, for
this type of
product to be effective several practical requirements must be rnet. To begin
with, the size
and shape of the unit dose container must be readily compatible with the
geometry of a wide
variety of rinse cycle dispensers designed for home washing machines in order
to insure its
easy introduction into the dispenser. Moreover, in common with the general use
of rinse
cycle softeners, it is necessary to clean the rinse dispenser on a regular
basis to avoid residue
from accumulating within the dispenser or even, at times, prevent bacterial
growth from
occurring.
Still further, a unit dose composition for the rinse cycle must be formulated
to readily
dispense its contents upon contact with water in a period of time
corresponding to the
residence time of the unit dose in the dispenser, namely, the period of time
during which
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water enters and flows through the rinse cycle dispenser. The aforementioned
practical
requirements have to date not been successfully met with any commercially
available product
and hence there remains a need in the art for a unit dose softener capable of
activation in the
rinse cycle.
Laundry detergent compositions which further include a fabric softener to
provide
softening or conditioning of fabrics in the wash cycle of the laundering
operation are well-
known in the art and described in the patent literature. See, for example,
U.S. Patent
4,605,506 to Wixon; U.S. Patent 4,818,421 to Boris et al. and U.S. Patent
4,569,773 to
Ramachandran et al., all assigned to Colgate-Palmolive Co., and U.S. Patent
4,851,138
assigned to Akzo. U.S. Patent 5,972,870 to Anderson describes a multi-layered
laundry tablet
for washing which may include a detergent in the outer layer and a fabric
softener, or water
softener or fragrance in the inner layer. But, these type of multi-benefit
products suffer from
a common drawback, namely, there is an inherent compromise which the user
necessarily
makes between the cleaning and softening benefits provided by such products as
compared to
using a separate detergent composition solely for cleaning in the wash cycle
and a separate
softening composition solely for softening in the rinse cycle. In essence, the
user of such
detergent softener compositions does not have the ability to independently
adjust the amount
of detergent and softener added to the wash cycle of a machine in response to
the cleaning and
softening requirements of the particular wash load.
Some attempts have been.made in the art to develop wash cycle active fabric
softeners, typically in powder form. But, these type products are
characterized by the same
inconvenience inherent with the use of powered detergents, namely, problems of
handling,
caking in the container or wash cycle dispenser, and the need for a dosing
device to deliver
the desired amount of active softener material to the wash water.
The use of a unit dose wash cycle fabric softening composition in the form of
a
compacted granular tablet offers numerous advantages, but it is important that
such tablets be
sufficiently hard and not friable so as to withstand handling and
transportation without
brealcing or fragmenting. In order to achieve the desired level of hardness,
tablet makers
generally tend to increase the compacting pressure. But, a high compacting
pressure, if
favorable to the hardness of the tablet, lowers the disintegration rate of
such tablet.
To be effective, the unit dose fabric softening compositions, which are
compacted
granular compositions, must be able to disperse in the wash liquor in a short
period of time to
avoid any residue at the end of the wash cycle.
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Typically, the wash cycle time can be as short as 12 minutes and as long as 90
minutes
(in typical European washers) depending on the type of washer and the wash
conditions.
Therefore, to make sure that the compacted unit dose is properly dispersed in
the wash liquor
before the end of the cycle, disintegrating materials must be added to the
granules before
compacting. This need for disintegrating agents is well-known in the art and
the most popular
materials used for this purpose are water swelling polymers such as
polyvinylpyrrolidone,
cellulosic polymers or a blend of citric acid and bicarbonate salt that
provide an effervescent
matrix.
The problem with these disintegrating materials and swelling polymers is that
they
constitute a significant weight and cost of the overall composition and they
serve only he
single purpose of dispersion of the tablet. Also the use of a typical
effervescent matrix results
in a typical feel of the tablet surface that can be described as dry and
"stony", which is
generally not favored by consumers.
It has now been found that a particular grade of clay (described in WO
00/03959) can
replace the usual disintegrating agents while contributing to the softness of
the clothes. The
use of such clay enhances the disintegration rate of the unit dose while
allowing the use of
higher compacting pressure and reducing the friability of the dose. Moreover,
it provides the
finished tablet with a very smooth feel.
Summary of the Invention
The present invention provides a unit dose wash cycle fabric softening
composition
for softening or conditioning fabrics in the wash cycle of an automatic
washing machine, said
unit dose comprising (a) a compacted granular fabric softener composition, the
amount of (a)
being sufficient to form a unit dose capable of providing effective softening
or conditioning of
fabrics in the wash cycle of said washing machine, and wherein said fabric
softener
composition comprises a treated montmorillonite-containing clay selected to
have initial
properties as follows:
(i) a montmorillonite content of at Least 85%; and
(ii) when said clay is activated with sodium ions, dried and ground to
particles, said
ground particles do not swell more than about 2.5 fold over a period of 24
hours when added
to deionized water at room temperature; and wherein said montmorillonite-
containing clay is
treated by the process comprising the following sequential steps:
(a) drying said clay to a moisture content of from about 25 to about 35%, by
weight;
(b) extruding the dried material through a die to form a paste;
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(c) drying said paste to a moisture content of from about 10% to about 14% by
weight; and
(d) calcining at a temperature of about 120°C to about 250°C.
In a preferred embodiment the unit dose fabric softening composition is
characterized
by being in the form of a tablet and having no discrete outer layer
surrounding the fabric
softener comprised of an alkaline material such that the pH of the wash water
is increased
upon dissolution of said outer layer in said wash water.
The term "granular" as used herein in describing the fabric softener is
intended to
encompass relatively coarser granules varying in size from about 150 to 2,000
microns as well
as finer powder having a size as small as 30 to 50 microns.
The term "fabric softener" is used herein for purposes of convenience to refer
to
materials which provide softening and/or conditioning benefits to fabrics in
the wash cycle of
a home or automatic laundering machine.
The compacted granular fabric softener composition of the invention is
preferably
comprised of a fabric softening clay optionally in combination with an organic
fatty softening
material. Especially preferred fabric softeners comprise a clay mineral
softener, such as
bentonite, in combination with a pentaerythritol ester compound as further
described herein.
Useful combinations of such softener may vary from about ~0°Io, to
about 90%, by weight, of
clay, and from about 10% to about 20%, by weight, of fatty softening material
such as a
pentaerythritol compound (often abbreviated herein as "PEC").
The present invention is predicated on the use of a treated montmorillonite-
containing
clay, preferably a treated bentonite, as herein defined, as an active
softening ingredient in a
unit dose softening composition for the wash cycle. The resultant unit dose
composition has
reduced tendency to gel on contact with water so that when used in conjunction
with laundry
detergent compositions it manifests improved dispersion properties in the wash
water without
having any adverse effect on its softening properties.
In accordance with the process aspect of the invention there is provided a
process for
softening or conditioning laundry which comprises contacting the laundry with
an effective
amount of the unit dose laundry composition defined above.
Detailed Descriution of the Invention
The clays that are useful components of the invented products are those which
cooperate with the organic fatty softener materials to provide enhanced
softening of laundry.
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Such clays include the montmorillonite-containing clays which have swelling
properties (in
water) and which are of smectite structure, so that they deposit on fibrous
materials,
especially cotton and cotton/synthetic blends, such as cotton/polyester, to
give such fibers and
fabrics made from them a surface lubricity or softness. The best of the
srnectite clays for use
in the present invention is bentonite and the best of the bentonites are those
which have a
substantial swelling capability in water, such as the sodium and potassium
bentonites. Such
swelling bentonites are also known as western or Wyoming bentonites, which are
essentially
sodium bentonite. Other bentonites, such as calcium bentonite, are normally
non-swelling
and usually are, in themselves, unacceptable as fabric softening agents.
However, it has been
found that such non-swelling bentonites exhibit even better fabric softening
in combination
with PEC's than do. the swelling bentonites, provided that there is present in
the softening
composition, a source of alkali metal or other solubilizing ion, such as
sodium (which may
come from sodium hydroxide, added to the composition, or from sodium salts,
such as
builders and fillers, which may be functional components of the composition).
Among the
preferred bentonites are those of sodium and potassium, which are normally
swelling, and
calcium and magnesium, which are normally non-swelling. Of these it is
preferred to utilize
calcium (with a source of sodium being present) and sodium bentonites. The
bentonites
employed may be produced in the United States of America, such as Wyoming
bentonite, but
also may be obtained from Europe, including Italy and Spain, as calcium
bentonite, which
may be converted to sodium bentonite by treatment with sodium carbonate, or
may be
employed as calcium bentonite. Also., other rnontmorillonite-containing
smectite clays of
properties like those of the bentonites described may be substituted in whole
or in part for the
bentonites described herein and similar fabric softening results will be
obtained.
The swellable bentonites and similarly operative clays are of ultimate
particle sizes in
the micron range, e.g., 0.01 to 20 microns and of actual particle sizes in the
range of No's.
100 to 400 sieves, preferably 140 to 325 sieves, U.S. Sieve Series. The
bentonite and other
such suitable swellable clays may be agglomerated to larger particle sizes
too, such as 60 to
120 sieves, but such agglomerates are not preferred unless they include the
PEC('s) too (in
any particulate products).
For purposes of providing a treated bentonite in accordance with the
invention, the initial
bentonite starting material is selected to have relatively low gelling and
swelling properties.
Specifically, the starting material bentonite is selected to have the
following initial properties:
(a) a montmorillonite content of at least 85%; and (b) when the beritonite is
activated with
sodium ions, dried and ground to particles, the ground particles do not swell
more than about
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2.5 fold over a period of 24 hours when added to deionized water at room
temperature. The
ground particles of bentonite for purposes of determining swelling herein are
particles at least
90% of equal to or less than about 75 microns in diameter.
The chemical composition of the starting material bentonite is preferably
comprised
by weight of the following:
Si02 55.0 to 61.0%
A1203 14.5 to 17.6%
Fe203 1.45 to 1.7
%
CaO 2.8 to 7.0%
Mg0 5.0 to 6.3 %
K20 0.5 to 0.85%
NazO ~ 0.25 to 0.30%
Mn304 0.04 to 0.25 %
The process of treating the bentonite comprises the following sequential
steps:
(a) drying said clay to a moisture content of from about 25 to about 35%, by
weight;
(b) extruding the dried material through a die to form a paste;
(c) drying said paste to a moisture content of from about 10% to about 14% by
weight; and
(d) calcining at a temperature of about 120°C to about 250°C.
A detailed description of the process for treating bentonite in accordance
with the
present invention is disclosed in WO 00/03959 filed in the name of Colin
Stewart Minchem,
Ltd., the disclosure of which is incorporated herein by reference.
A main component of the invented compositions and articles of the present
invention,
and which is used in combination with the fabric softening clay is an organic
fatty softener.
The organic softener can be anionic, cationic or nonionic fatty chains (Clo-
C22 preferably Cla-
Cl8). Anionic softeners include fatty acids soaps. Preferred organic softeners
are nonionics
such as fatty esters, ethoxylated fatty esters, fatty alcohols and polyols
polymers. The organic
softener is most preferably a higher fatty acid ester of a pentaerythritol
compound, which term
is used in this specification to describe higher fatty acid esters of
pentaerythritol, higher fatty
acid esters of pentaerythritol oligomers, higher fatty acid esters of lower
alkylene oxide
derivatives of pentaerythritol and higher fatty acid esters of lower alkylene
oxide derivatives
of pentaerythritol oligomers. Pentaerythritol compound is often abbreviated as
PEC herein,
which description and abbreviation may apply to any or all of pentaerythritol,
oligomers,
thereof and alkoxylated derivatives thereof, as such, or more preferably and
more usually, as
the esters, as may be indicated by the context.
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The oligomers of pentaerythritol are preferably those of two to five
pentaerythrztol
moieties, more preferably 2 or 3, with such moieties being joined together
through etheric
bonds. The lower alkylene oxide derivatives thereof are preferably of ethylene
oxide or
propylene oxide monomers, dimers or polymers, which terminate in hydroxyls and
are joined
to the pentaerythritol or oligomer of pentaerythritol through etheric
linkages. Preferably there
will be one to ten alkylene oxide moieties in each such alkylene oxide chain,
more preferably
2 to 6, and there will be one to ten such groups on a PEC, depending on the
oligomer. At
least one of the PEC OH groups and preferably at least two, e.g., 1 or 2 to 4,
are esterified by
a higher fatty acid or other higher aliphatic acid, which can be of an odd
number of carbon
atoms.
The higher fatty acid esters of the pentaerythritol compounds are preferably
partial
esters. And more preferably there will be at least two free hydroxyls thereon
after
esterification (on the pentaerythritol, oligomer or alkoxyalkane groups).
Frequently, the
number of such free hydroxyls is two or about two but sometimes it may by one,
as in
pentaerythritol tristearate. The higher aliphatic or fatty acids that may be
employed as
esterifying acids are those of carbon atom contents in the range of 8 to 24,
preferably 12 to 22
and more preferably 12 to 18, e.g., lauric, myristic, palmitic, oleic, stearic
and behenic acids.
Such may be mixtures of such fatty acids, obtained from natural sources, such
as tallow or
coconut oil, or from such natural materials that have been hydrogenated.
Synthetic acids of
odd or even numbers of carbon atoms may also be employed. Of the fatty acids
lauric and
stearic acids are often preferred, and such preference may depend on the
pentaerythritol
compound being esterified.
Examples of some esters (DEC's) within the present invention follow:
Mononentaerythritol Esters
CH2- Rz
Rl - CH2 - C - CHZ - R3
CH2 R4
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Monopentaerythritol Dilaurate
Rl=CH3 - (CHZ)io -COO-
RZ=CH3 - (CH2)io -COO-
R3=OH
R4=OH
Monopentaerythritol Monostearate
RI=CH3 - (CH2)i6 -COO-
RZ=OH
R3=OH
R4=OH
Monopentaerythritol Distearate
Rl=CH3 - (CHZ)i6 -COO
R2=CH3 - (CHZ)i6 -COO
R3=OH
R4=OH
Monopentaerythritol ~ristearate
, Rl=CH3 - (CH2)m -COO-
Ra=CH3 - (CHZ)is -COO-
Rs=CH3 - (CH2)1~ -COO-
R4=OH
Monopentaerythritol Monobehenate
Ri=CH3 - (CH2)zo -COO- _
R2=OH
R3=OH
R4=OH
Monopentaerythritol Dibehenate
Ri=CH3 - (CH2)ao -COO
Rz=CH3 - (CHZ)ao -COO
R3=OH
R4=OH
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Dipentaerythritol Esters
CH20Rl CH20R2
( I
HO CH2- C- CHZ- O -CH2- C-' CH~OH
CHZOR3 CH20R4
Dipentaerythritol Tetralaurate
Rl=CH3 - (CHZho
-CO
R~=CH3 - (CH2)io
-CO
R3=CH3 - (CHZ)io
-CO
R~=CH3 - (CHZ)io
-CO
Dipentaerythritol Tetrastearate
Ri=CH3 - (CHZ)is -CO
R2=CH3 - (CH2)is -CO
R3=CH3 - (CH2)is -CO
R~.=CH3 - (CH2)is -CO
Pentaerythritol 10 Ethylene Oxide Ester
CH2- O- (CHI- CH20)nH
I
Rl_CH2_C-CHz--Ra
I
CHZ- O- (CH2- CH20)n~H
with n + n' = 10
Monopentaerythritol 10 Ethylene Oxide Distearate
Rl=CH3 - (CH2)is -COO-
R2=CH3 - (CH2)i6 -COO-
Pentaerythritol 4 Propylene Oxide Esters
CHZ - O - (CH2 - CH - CHZO)ZH
Rl - CH2 - C- CH2- RZ
CH2 - O = (CHZ - CH - CH20)ZH
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Monopentaerythritol 4 Propylene Oxide Monostearate
Rl=CH3 - (CHZ)i6 -COO-
R2=OH
Monopentaerythritol 4 Propylene Oxide Distearate
Rl=CH3 - (CH2)is -COO-
R2=CH3 - (CH2)16 -COO-
Although in the formulas given herein some preferred pentaerythritol compounds
that
are useful in the practice of this invention are illustrated it will be
understood that various
other such pentaerythritol compounds within the description thereof may also
be employed
herein, including such as pentaerythritol dihydrogenated tallowate,
pentaerythritol ditallowate,
pentaerythritol dipalmitate, and dipentaerythritol tetratallowate.
To enhance the softening efficacy of the unit dose compositions described
herein
cationic softeners such as conventional quaternary ammonium softening
compounds may
optionally be added in minor amounts.
The combination of bentonite and organic fatty softening material is generally
from
about 10% to about 100% bentonite and from about 1% to about 100% fatty
softening
material, preferably from about 50% to about 95% bentonite and about 5% to
about 50% fatty
softening material, and most preferably from about 80% to 90% bentonite and
from about
10% to about 20% fatty softening material.
Other useful ingredients for the unit dose compacted granular compositions of
the
invention include disintegration materials to enhance the disintegration of
the unit dose in the
wash water. Such materials include an effervescent matrix such as citric acid
combined with
baking soda, or materials such as PVP polymer and cellulose. Granulating
agents may be
used such as polyethylene glycol; bactericides, perfumes, dyes and materials
to protect against
color fading, dye transfer, anti-pilling and anti-shrinkage. For purposes of
enhancing the
aesthetic properties of the final composition, cosmetic ingredients such as
dyes, micas and
waxes may be used as coating ingredients to improve the appearance and feel of
the unit dose.
The encapsulation provided for the liquid or granular softening or
conditioning
materials is preferably a gelatin shell which is readily soluble in the wash
water and
compatible with detergents used in the wash cycle. The manufacture of such
gelatin capsules
utilizes technology well known in the art and is described, for example, in
the following
publications which are incorporated herein by reference: "Snftgels:
Manufacturing
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Considerations", Paul Wilkinson and Foo Song Hom, Drugs Pharmaceutical Science
(1990),
pps. 409-449, Mediventure Inc., Ann Arbor, MI, USA; and "Coating of Gelatin
Capsules",
Ann Mari Hannula and Peter Speiser, Acta Pharmaceutical Technology (1988),
pps. 234-236.
Preferred liquid softeners of the invention include fatty alcohols, such as
oleyl alcohol,
fatty acids, such as oleyl carboxylic acid; fatty esters, such as oleyl esters
or vegetable fatty
esters such as sunflower oil ; silicones, such as polydimethylsiloxanes,
linear or crosslinked,
ethoxylated or without ethoxylation and optionally including an amide
functionality;
polyethylene waxes, having a molecular weight of from 8,000 to 60,000; and
fatty amides,
such as dioleyl amide formed by the reaction of diethylene triamine with oleic
acid having
predominantly the following structure:
R1-C- N-- CH2- CH2- NR2- CH2-N - C- Rl
wherein Rl represents an oleyl allcyl carbon chain; and RZ represents H or
(EO)X with x
varying from 0 to 6 (the degree of ethoxylation).
While the oleyl carbon chain length is most preferred for purposes of
providing
softening efficacy and dispersion in the wash water, other higher alkyl chain
lengths may also
be used for the invention. .
Typical unit dose compositions for use herein may vary from about 5 to about
10 ml
corresponding on a weight basis to about 5 to about 10 grams (which includes
the weight of
the capsule), and the number of doses per wash is two. Alternatively, when
using 1 unit
dose/wash, the corresponding volume and weight is from about 10 to about 20 ml
and from
about 10 to about 20 grams (including the capsule weight), respectively.
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Example 1
Compacted granular unit dose compositions (A and B) were prepared from the
following ingredients:
Wei ht Perc_e_nt
_ A B
__ 80.0% 78.7%
Clay/Pentaerythritol ditallowate
(PDT) in a
ratio of 83% : 17%
Effervescent matrix of baking 17 ----
soda and citric
acid
Pol vin 1 rrolidone 1 ----
Perfume 2 2.9
Treated bentonite ---- 18.4
Composition A was a comparative composition and Composition B was a
composition
in accordance with the invention containing treated bentonite clay.
The method of manufacture consisted of mixing all the ingredients with the
exception
of perfume in a Loedige-type mixer. The resulting blend was dried in an oven
and perfume
was then added to the dried powder. The powder was then compacted using an
alternative or
rotative press mounted with appropriate dyes. The weight of the spherical unit
dose was 60g
and such unit dose dispersed in water within 20 minutes when introduced in the
wash load at
the beginning of the wash in a European Miele W832 front loading washing
machine set a
Program White Colors at 40°C.
The softness provided by the unit dose compositions of A and B on terry
towels,
cotton tee-shirts and cotton kitchen towels was evaluated after cumulative
washes and
compared with a commercial liquid fabric softener. A 3Kg laundry ballast was
used in the
machine. Softness was evaluated by a panel of six judges using 9 replicates.
The results were
as follows:
The softness performance of Compositions A and B were essentially equivalent.
As compared to a commercial liquid fabric softener, Compositions A and B
provided
equivalent softness after one wash cycle with regard to cotton tee-shirts and
cotton kitchen
towels.
A comparison of Compositions A and B with regard to physical properties and
dispersion in water is shown below:
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Com osition Friabilit Hardness ~~ Dis ersion time in water
~ ~ ~ ~~
A 57% 75 r 50 min.
B 12% 100 9 min.
~l~ Friability: Measurement of the residues in the bottom receptacle after
sieving during 15
minutes (amplitude 4) on a vibrating 4 mm meshes sieve; the lower, the less
friable.
~Z~ Hardness: Resistance to breakage when various weights are falling onto the
sphere; the
higher, the more resistant.
C3~ Dispersion in beaker: Dispersion time of 1 sphere in 1 cold water beaker
under moderate
agitation; the shorter, the better.
Composition B provided a significantly smoother feel and texture to the touch
as
evaluated by a panel of judges as compared to Composition A.
13
