Note: Descriptions are shown in the official language in which they were submitted.
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CLEANING COMPOSITIONS,
METHODS, AND/OR ARTICLES FOR HARD SURFACES
TECHNICAL FIELD
The present invention relates to compositions, methods and/or articles for
removing dirt and other unwanted residues from hard surfaces, especially those
surfaces
which are contacted by food intended for ingestion by humans or lower animals.
BACKGROUND OF THE INVENTION
Alkaline liquid hard surface cleaning compositions are well known in the art.
The alkalinity provides improved grease cleaning properties but typically is
employed in
conjunction with other components which require careful rinsing of the cleaned
surface
before this surface could be used in any direct contact with items intended
for ingestion
by humans or lower animals. Conventional hard surface cleaners typically
include
inorganic and organic compounds which would be unacceptable if transferred to
foods
which contact the cleansed surface. Some cleaners employ bleaching agents,
abrasives,
and/or solvents which could also negatively impact food items.
Another consideration on formulation of hard surface cleaners, particularly
those
not intended to be thoroughly rinsed off after use, is the film/streak
performance after
wiping and drying of the cleaner on the surface. It is well known that liquid
cleaning
compositions, and especially compositions prepared for cleaning glass and
kitchen tile,
need exceptionally good filming/streaking properties. Because good
filming/streaking
properties are required especially for these cleaners, the levels of
surfactants and other
actives must be kept low in order to achieve this benefit. Such compositions
frequently
rely on the use of ammonia and strong organic solvents to achieve good
results.
It will be appreciated that the formulation of truly effective compositions,
especially those which can be used safely by individual consumers, for washing
hard
surfaces presents a unique problem to the formulator, inasmuch as many art-
disclosed
cleaning ingredients would, presumably, not be desirable for use in direct
contact with
foods where they might not be fully removed.
Moreover, it would be especially desirable to provide effective,
toxicologically-
acceptable cleaning compositions for hard surfaces in the form of
substantially low-
sudsing liquid solutions which are clear or which have only minimal haziness.
Liquid
solutions are convenient for the user, since they can be applied directly to
hard surfaces,
followed by wiping. The clarity of the liquids connotes cleanliness to the
user and is
thus highly desirable. Low sudsing is an important attribute so that removal
of the
CONFIRMATIOrV COPY
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solution by wiping is achieved quickly and easily. It would also be of
advantage if such
compositions could be provided in the form of concentrates, which could be
diluted by
the consumer before use and/or applied to the surfaces as a direct spray-on.
Unfortunately, many toxicologically-acceptable cleaning ingredients do not
meet
the aforesaid requirements for clear, low-sudsing, dilutable liquid products.
Many
detersive surfactants form cloudy or even opaque suspensions in water. Of
course, many
surfactants are specifically designed to be high sudsing. Still others form
relatively
intractable phases in their concentrated form.
It has now been discovered that certain anionic and nonionic surfactants,
properly
formulated with other ingredients can provide liquid compositions having the
desired
properties described above.
BACKGROUND ART
The use and selection of cleaning ingredients for the purpose of washing
fruits
and vegetables is described by the United States Code of Federal Regulations,
Title 21,
Section 172, 173, 182, and/or 184. These regulations restrict the ingredients
that may be
used for direct contact with food to those described as "generally regarded as
safe"
(GRAS), and a few other selected ingredients. For purposes of the present
invention,
ingredients that are food additives permitted for direct addition to food for
human
consumption as defined as "food grade". These sections also provide certain
limitations
on the amount of material that can be used in a given context.
Among these ingredients, the experienced formulator will find only a few
ingredients which can provide effective cleaning of hydrophobic residues, such
as waxes,
oils, or man-made chemical residues. It is recognized these types of residues
are
removed most readily by surface active ingredients in water, or by organic
solvents
largely in the absence of water. Other types of soils, especially particulate
insoluble soils
that do not readily disperse in water, are effectively removed by surface
active materials
in water, especially when aided by complex anionic salts, such as citrates
(polycarboxylates), or polyphosphate salts.
Within this limited group of ingredients the range of effective cleaning
compositions well suited to the task of cleaning foods such as fruits and
vegetables,
especially as practiced by individual consumers, have been previously
described in U.S.
Patents 5,500,048, 5,500,143, 5,500,295, and 5,503,764. This prior art,
however, deals
primarily with problems associated with cleaning fruits and vegetables and
does not take
into consideration the unique characteristics, including the superior
film/streak
performance, of the present invention.
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SUMMARY OF THE INVENTION
The present invention encompasses compositions, articles of commerce, and
methods for cleaning hard surfaces, especially those surfaces which are
contacted by
food intended for ingestion by humans or lower animals. The compositions
demonstrate
4
superior film/streak performance.
These aqueous compositions are suitable for cleaning hard surfaces, even when
the compositions are incompletely removed from said surfaces. Such a
composition
comprises only food grade ingredients, has a pH of greater than 11.6,
preferably greater
than about 12.0, more preferably greater than about 12.5, and is essentially
free of C8-C~g
fatty acid or salts thereof. In order to deliver superior fiim/streak
performance, said
compositions preferably comprise less than about 2.0%, by weight of the total
composition, more preferably below about 1.75%, and even more preferably below
about
1.0% of non-volatile components. The compositions of the present invention
comprise:
(a) from about 0.001 % to about 1 %, by weight of the composition, preferably
from about 0.005% to about 0.5%, more preferably from about 0.01% to
about 0.1 %, of nonionic and/or anionic surfactant;
(b) up to about 6% by weight of the composition, preferably from about 0.01 %
to
about 4%, more preferably from about 0.1 % to about 2% of GRAS perfume;
(c) a toxicologically acceptable alkali compound;
(d) optionally, a toxicologically acceptable sequestrant/builder;
(e) optionally, a toxicologically-acceptable preservative; and
(fj the balance comprising aqueous carrier selected from water and,
optionally,
low molecular weight, toxicologically-acceptable organic solvent.
Preferred compositions for use herein contain only materials that are GRAS,
including, of course, direct food additives affirmed as GRAS, to protect
against possible
misuse by the consumer.
A particularly preferred embodiment of the present invention comprises a
composition suitable for cleaning hard surfaces, even when the composition is
incompletely removed from said surfaces, comprising only food grade
ingredients;
wherein said composition consists essentially of
(a) from about 0.005% to less than 0.5%, preferably from about 0.01% to about
0.1 % of nonionic or anionic surfactant, preferably anionic;
(b) from about 0.01 % to about 4%, preferably from about 0.1 % to about 2%, by
weight the composition, of GRAS perfume;
(c) a toxicologically-acceptable alkali compound;
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(d) from about 0.5% to about 8%, preferably from about 2 to about 6% of low
molecular weight, toxicologically-acceptable organic solvent; and
(e) the balance comprising water;
said composition having a pH of greater than 11.6, preferably greater than
12.0, and even
more preferably greater than 12.5. Surprisingly, this formulation provides
superior
cleaning performance without the traditional builders, sequestrants or other
components
traditionally found in hard surface cleaning compositions.
The present invention also encompasses methods of using said compositions
comprising contacting hard surfaces by direct application of said compositions
in an
amount effective to clean said surfaces. The compositions of the present
invention are
particularly effective at cleaning greasy build-up, and coffee, tea and juice
stains
commonly found in kitchen environments.
Another preferred variation in the above methods for cleaning hard surfaces
involves placing said cleaning compositions in a spray container to provide a
spray of
said composition to distribute the said composition, or compositions, over the
surfaces
while utilizing only a minimum amount of the cleaning solution and minimizing
the
exposure of the remaining solution to the atmosphere, where the solution is
more likely
to be contaminated and/or exposed to oxygen, both of which tend to cause
undesirable
changes in the solutions from aesthetic and/or performance considerations. In
such spray
processes, there is only need for a relatively small amount of material in the
package, and
for individual consumer use, this is desirable, since some consumers will not
be able to
manipulate large weights.
The present invention also encompasses articles of commerce comprising a
container containing said cleaning compositions. For individual consumer
usage,
typically, the container will contain no more than about two gallons (about
eight liters),
preferably no more than about one gallon (about four liters), especially when
the
container is a spray container, even one that has a tube that permits the
spray device to be
manipulated while the bulk container remains in place. More preferably such
spray
containers contain about one liter, or less, of cleaning solution.
The present invention, especially the methods involving use of hand held
trigger
activated spray means are primarily/solely suitable for use by individual
consumers so
that it is essential that extra safety be built into the product. The
compositions described
herein are intended to be used without a rinsing step. After cleaning hard
surfaces, the
cleaning compositions of the present invention are designed to be wiped from
the
surface. Failure to rinse thoroughly after cleaning is less of a concern if
all of the
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ingredients are GRAS. This is especially important when concentrated basic
compositions are employed.
The ingredients in the above compositions are preferably selected and used in
proportions which provide substantially cleave compositions. "Substantially
clear"
includes only minimal haziness, and preferably the compositions are completely
clear.
The ingredients are also selected to have minirr~al odor, both initially and
after storage.
The lack of odor is especially important in compositions for use on food.
All percentages
are by weight of the composition unless otherwise indicated. All temperature
readings
are understood to be done at standard tem~aerature and pressure unless
otherwise
indicated.
DETfIILED DESCRIPTION OF THE INVENTION
The following toxicologically-acceptable ingredients are used in the
preparation
of the preferred compositions herein. By °'toxic;ologically-acceptable"
is meant that..any
residues from the ingredients of the compositions which may remain on the hard
surfaces
cleansed therewith are safe for ingestion by humans and/or lower animals.
The present invention encompasses aqueous compositions suitable for cleaning
hard surfaces, even when the composition is incompletely removed from said
surfaces,
comprising only food grade ingredients; wherein said composition comprises
from about
0.001 % to about 1.0% of nonionic and/or anioiuc surfactant; said composition
having a
pH of greater than l 1.b, and wherein said composition is essentially free of
Cg-C,8 fatty
acid or salts thereof.
SURFACTANT
An essential ingredient in compositions, of the present invention is a food
grade
surface active compound. Base stable anionic surfactants can be employed, as
allowed by
the United States Code of Federal Regulations, Title 21, Section 173.31 S.
Preferred are
salts of dodecylbenzene sulfonate. Also described in the CFR are phosphate
esters of
ethylene and/or ethylenelpropylene oxide adducts of aliphatic alcohols,
dioctyl
sulfosuccinate, or 2-ethylhexyl sulfate.
The anionic surfactants are suitably water-soluble alkyl or alkylaryl
compounds,
the alkyl having from about 6 to about 20 carbons, including a sulfate or
sulfonate
substituent group. Depending upon the level of cleaning desired one can use
only the
anionic detergent surfactant, or, less preferably, the anionic detergent
surfactant can be
combined with a cosurfactant. Nonionic surfactants, e.g., ethoxylated aIcohols
and/or
alkyl phenols, can also be used as cosurfactants. or replace the anionic
altogether.
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The anionic detergent surfactants herein are selected from the group
consisting of
C(,-C2p alkyl sulfates, alkyl ethoxy ether sulfates, alkyl benzene sulfonates,
olefin
sulfonates, and mixtures thereof. Preferably said surfactant is selected from
sodium
sulfates and sulfonates, in particular, sodium alkyl sulfates, sodium n-
alkylbenzene
sulfonates, sodium mono- and dimethyl naphthalene sulfonates. More preferably,
the
anionic detergent surfactant is C(-C20 alkyl sulfate, more preferably Cg-C 1 (
alkyl
sulfate. In order to provide superior cleaning performance, yet retain
acceptable
film/streak performance, it is preferable that more than about 95%, by weight
of said
surfactant, of said surfactant has an alkyl chainlength of C,o to C,6. It is
even more
preferable that more than about 50%, by weight of said surfactant, of said
surfactant has
an alkyl chainlength of C12.
The nonionic surfactant is preferably selected from materials known well-known
in the art, such as alkylene oxide (ethylene oxide or propylene oxide) adducts
of C 10-18
aliphatic alcohols or acids, C10-18 aliphatic alcohol adducts of glucose
(alkyl
polyglucosides). The specific nonionic surfactant selected ideally has a
hydrophilic-
lipophilic balance (HLB) greater than about 10, and a cloud point above about
35°C in
the composition. The United States Code of Federal Regulations (CFR)
specifically
describes an ethylene oxide/propylene oxide adduct of C12-18 aliphatic alcohol
of
molecular weight of about 800. Such a material is available as PLURAFAC RA-20
(BASF).
It is to be appreciated that in basic compositions the alkoxylated alcohol
functions
mainly as a dispersant for any soap curd which may form during the cleansing
operation.
Further, it is recognized that the selection of non-nitrogen containing
nonionics can
minimize the possibility of microbial growth in the dilute surfactant
compositions.
The levels of anionic and/or nonionic surfactant useful in the present
invention
are determined by cleaning and film/streak performance and also by the levels
deemed
safe as food grade. The surfactants of the present invention are present at
levels of from
about 0.001 % to about 1 %, by weight of the composition, preferably from
about 0.005 to
below 0.5%, and more preferably from about 0.01 % to about 0.1 %.
ALKALI COMPOUND
The pH of the composition is essential to the superior cleaning performance of
the compositions described herein. These highly basic compositions demonstrate
superior cleaning performance on tough stains typically found in kitchen
environments.
Unusually stubborn stains such as those left by coffee, tea, and juices are
effectively
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cleaned by these compositions. The pH of compositions of the present invention
are
above 11.6, preferably above 12, and even more preferably above 12.5.
Toxicologically-acceptable alkali compounds can be used in the compositions
herein to maintain product pH in the basic range. In general terms, alkali
compounds are
defined as substances which have a pH value of greater than 7.0 in aqueous
solution.
Carbonates, bicarbonates and hydroxides are convenient and preferred alkali
compounds.
For ease of formulatability, and improved stability, it is highly preferred
that such alkali
compounds be in their sodium salt form. Sodium bicarbonate is a highly
desirable
material to add to the compositions of this invention as a part of the
buffering system
since it is readily available as baking soda in food grade and is therefore
relatively
inexpensive, while providing a highly desirable purity to the composition.
Sodium
hydroxide is also a highly preferred ingredient.
Compositions formulated with a mixture of potassium and sodium cations in
molar ratios of from about 1:1 to about 10:1, preferably from about 2:1 to
about 8:1,
more preferably from about 4:1 to about S:1 potassium to sodium, e.g., as
provided by
mixtures of potassium hydroxide (hydrate) and sodium bicarbonate, have
desirable
rheological properties in some respects. The compositions are thick, so as to
cling to the
surfaces until spread, but are readily dispensed, e.g, by means of a spray
device, either
aerosol or finger-activated pump. The levels and identities of the ingredients
are adjusted
to provide products having the desired viscosities as set forth herein, e.g.,
more than
about 5, preferably more than about 10, more preferably more than about 50
centipoise
when at rest, and less than about 150, preferably less than about 100, more
preferably
less than about 50 centipoise under shear of >_ 1000 sec-1.
The ability of the preferred compositions containing mixtures of both sodium
and
potassium cations to shear thin is important to promote easy dispensing,
especially when
the compositions are sprayed, while maintaining the ability to be thick,
cling, and delay
run off after being applied to the hard surfaces.
However, the presence of a mixed cation buffer system, particularly with
respect
to the possible presence of cations associated with anionic surfactants , can
also lead to
product instability. Therefore a highly preferred embodiment of the present
invention,
especially when formulating with anionic surfactant systems, is one wherein
the cation
associated with the anionic surfactant is the same as that associated with the
alkali
compound. In this respect, the use of sodium sulfates and/or sodium sulfonates
in
conjunction with sodium hydroxide, carbonate and/or bicarbonate is highly
preferred,
particularly in the case where said composition is essentially free of
potassium cations
from other sources.
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SOLVENT
The major proportion (typically, 90%-98%, by weight) of the compositions
herein comprises water as the solubilizing carri~°r for the
ingredients. The compositions
also comprise an organic co-solvent. In order to be consistent with the spirit
of the
present invention, the organic solvent must be one regarded as acceptable for
use in the
food industry. As noted in the Examples hereinafter, water-ethanol can be
employed
and is especially preferred when formulating the basic pH compositions herein.
Other
compatible, water-soluble, low molecular weight solvents such as glycerol,
isopropyl
alcohol and propylene glycol can also be used. 'I,"he solvent level should not
exceed 10°l0
in the solution used to clean surfaces, preferably is in the range of about
0.05% to about
10%, by weight of the composition, more preferably from about 0.5% to about
8%, and
even more preferably from about 2% to about 6°/~.
PERFUME
Most hard surface cleaner products contaiin some perfitme to provide an
olfactory
aesthetic benefit and to cover any "chemical" odor that the product may have.
The main
function of a small fraction of the highly volatile, low boiling (having Iow
boiling
points), perfume components in these perfumes is to improve the fragrance odor
of the
product itself, rather than impacting on the subsequent odor of the surface
being cleaned.
However, some of the less volatile, high boiling perfiune ingredients can
provide a fresh
and clean impression to the surfaces, and it is sotnetimes desirable that
these ingredients
be deposited and present on the dry surface. For the purposes of the present
invention,
the term "perfume" is taken to include those ingredients which impart an
aesthetic
olfactory benefit. Such ingredients can include traditional perfumes, natural
extracts,
essences, and flavorings. The perfumes are preferably those that are more
water-soluble
and/or volatile to minimize spotting and filming. All of the perfumes useful
in the
present invention trust be "food grade" or GRAM at the levels employed in
order to be
consistent with the essential character of the invention. Of particular
usefulness are those
perfumes which impart a citrus or lime character to the composition. Some of
the
perfumes useful herein are described is more detail in U.S. Patent 5,108,660,
Michael,
issued April 28, 1992, at col. 8 lines 48 to 68, and col. 9 lines t to 68, and
col. 10 lines 1
to24, .. . ~ ~ _._,
SEOUESTRANTIBUILDER
Detergent builders that are effcient for hard surface cleaners and have
reduced
filming/streaking characteristics al the critical levels are an optional
element of the
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present invention. Organic poly carboxylic acids, especially those that are
GRAS, such as
citric, tartaric, malic, etc. acids, can be used. Ethylenediaminetetraacetic
acid (hereinafter
EDTA) is also an effective additive for this purpose.
These additional optional detergent builders, when present, are typically at
levels
of from about 0.001% to about 0.5%. more preferably from about 0.002% to about
0.3%,
most preferably from about 0.01% to about 0.15%. The levels of these
additional
builders present in the wash solution used for glass should be less than about
0.2%.
Therefore, typically, dilution is highly preferred for cleaning glass, while
full strength is
preferred for general purpose cleaning, depending on the concentration of the
product.
PRESERVATIVE
Formulating the present compositions at high pH reduces the tendency for
biological growth of contaminants, such as bacteria, fungi, or molds. Standard
food-
grade preservatives such as ethylenediaminetetraacetic acid and/or the salts
thereof, at a
level of from about 0.01 % to about 0.2% of ethylenediaminetetraacetic acid,
or its
sodium and/or potassium salts, can be used although, in general, the basic pH
compositions herein do not require a preservative.
The use of commercial surfactants containing unsaturated alkyl groups can be
complicated by development of off odors and/or yellowing of the compositions
in which
they appear. These undesirable properties are believed to be caused by complex
side
reactions initiated by the reaction of oxygen with primarily the
polyunsaturated
components. These results can be avoided, or minimized, by avoiding contact
with air,
or by controlling the quality of the alkyl substituents so that the amount and
type of
polyunsaturates are minimized as described above, and/or by the addition of
antioxidants.
It has been found, that the addition of tocopherols (e.g., Vitamin E, or
tocopherol
acetates) in alkaline formulations is advantageous, as they do not degrade,
nor do they
impart a strong color. They inhibit the development of off odors for extended
periods of
time so that the need for masking scents is minimized, or eliminated. The use
of
butylated phenols, such as BHT and BHA is also useful, but the quantity should
be
limited to avoid imparting colors to the compositions. Other food grade
antioxidants
such as Vitamin C and sulfites, are desirable to prevent deterioration of the
compositions
by the action of oxygen, but care must be taken since vitamin C can suffer
color
degradation and sulfites can cause odor problems. Sulfites also have been the
target of
potential health concerns.
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SPRY MEANS
The compositions herein are preferably used by placing them in a package
comprising either an aerosol container or a non-aerosol spray device "spray
means."
Said spray means is any of the manually activated, preferably "trigger-type,"
means for
producing a spray of liquid droplets as is known in the art. Typical spray
means are
disclosed in U.S. Pat. Nos.: 4,082,223, Nozawa, issued Apr. 4, 1978;
4,161,288,
~IcKinney, issued July 17, 1979; 4558,821, Tada et al., issued Dec. 17, 1985;
4,434,917,
Saito et al., issued Mar. 6, 1984; and 4,819,835, Tasak.i, issued Apr. I 1,
1989.
The spray bottle, or container can be any
of the ones commonly used for containing hard. surface cleaner detergent
compositions.
Examples of bottles are those in U.S. Design Pat. Nos.: 244,991, Weekman et
al., issued
3uly 12, 1977; and 275,078, Wassergord et al., issued Aug. ;14, 1984.
The spray means herein can also include those that incorporate a propellant
gas
into the liquid and those that will foam even detergent compositions having a
viscosity of
less than about I S cps. 'The device can also be one that can be adjusted to
either give a
liquid spray or a foam. The spray means herein are typically those that act
upon a
discrete amount of the composition itself, typically by means of a piston that
displaces
the composition and expels the composition through a nozzle to create a spray
of thin
liquid. The spray means can include a foaming spray head such as those
described in
U.S. Pat. Nos. : 4,350,298; 4,730,775; 4,883,22'7; and 4,890,'792.
An example of an acceptable commercially available
foaming spray head is model TS-800 with foaming nozzle manufactured by Calmar,
Inc..
USAG
The compositions described herein are used for cleaning inanimate, household
surfaces, especially those used in food production and other food-contacting
surfaces
(surfaces that come in contact with food). E.g;., cutting boards, counter
tops, utensils,
dishes, colanders, sinks, sponges, towels, dish cloths, cloth napkins
(serviettes), table
cloths, and other surfaces that come in contact with food. It is desirable to
disinfectJsanitize before the surfaces come in contact with the food, and is
desirable to
redisinfectlsanitize whenever the surfaces become recontaminated. The products
herein,
containing all GRAS ingredients, are perfect .for this purpose. On hard
surfaces, of
course, the compositions can be removed, after su~cient time has elapsed, by
rinsing or
by absorption/wiping with an appropriate object" e.g., paper towel, sponge,
squeegee, etc.
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The compositions are particularly well suited for removal by only wiping the
treated
surface.
EXAMPLES
The following Examples illustrate the compositions and processes of this
invention, but are not intended to be limiting thereof. The exemplified basic
liquid
compositions can be prepared at pH 11.6 to above 12.5 by dissolving the
ingredients in
water or water-ethanol using conventional mixing apparatus. Values are weight
percent
unless otherwise specified.
Ingredient Formula Formula Formula Formula
A B C D
Sodium Lauryl Sulfate 0.06 0.20 0.06
Sodium dodecylbenzene 0.10
sulfonate
Ethanol 5.0 5.0 5.0 4.0
Lime Perfume 1.0 1.0 1.5
Sodium Hydroxide 0.15 0.1 S 0.1 S 0.125
EDTA 0.10
Water 93.79 93.65 94.79 94.175
