Note: Descriptions are shown in the official language in which they were submitted.
~(3'77370
This invention concerns a liquid cleaning formu-
lation.
The removal of stubborn stains, such as fruit
juices, tea, coffee, or ink, from counter tops and like
surfaces is a particularly vexat:ious problem. Frequently,
such stains are found in the same area and are caused at the
same time as grease and oil spatters and spills such as may
occur on range tops during meal preparation. A variety of
aqueous detergent compositions axe available for cleaning the
grease and oil, but are ineffective against stains on the
counter tops which are usually a thermoset plastic laminate.
Powdered abrasive bleach products are available to remove
those stains but unless great care is exercised~ they will
destroy the gloss finish on painted and porcelainized
applicances and the plastic counter top.
Sodium hypochlorite has been used as a bleaching
agent for decades. However, it has no detergency. Also the
same properties that cause it to be effective against
organic stains from aqueous solution have precluded its
combination with organic detergents as an aqueous cleaning
preparation. In the past, sodium hypochlorite has been
combined in solution with inorganic detergents, such as tri-
sodium phosphate, or has been combined with organic deter-
gents as a dry granular powder which is dissolved in water
just prior to use.
The present invention provides a liquid cleaning
formulation consisting essentially of an aqueous solution of
(1) from 0.5 weight percent up to its limit of aqueous
solubility of a synthetic detergent selected from the group
consisting of (a) a water soluble alkali metal alkyl sulfate
1;,790A-F -1-
1~'7'7370
wherein said alkyl group is a straight chain moiety contain-
ing from about 6 to 20 carbon atoms, or (b) a water soluble
branched chain alkyl aryl sulfonate wherein the alkyl group
contains from 8 to 18 carbon atoms, or (c) water soluble
mixtures thereof, (2) not more than one weight percent o
said formulation of sodium hypochlorite and (3) a sufficient
amount of a water soluble alkal~ne builder to maintain the
pH of said formulation at above about 11.0 and wherein said
detergent is present in excess over the hypochlorite.
The above named classes of synthetic detergents
provide stable aqueous solutions with sodium hypochlorite.
One of the useful classes is the group of alkali metal alkyl
sulfates wherein the alkyl group is a straight chain of from
about ~ to about 20 carbon atoms. The length of the chain
is generally limited to the stated size by detergency
characteristics. Formulations of alkali metal alkyl sulfates
having straight chain alkyl groups exhibit substantially
improved hypochlorite stability in the aqueous solution over
such sulfates having branched chain alkyl groups. The pre-
ferred species providing optimum overall properties to the
formulations is sodium lauryl sulfate.
The second class of detergents useful herein are
the alkyl aryl sulfonates wherein the alkyl group is a
branched chain having from about 8 to 18 carbon atoms. Solu-
tions made with the isomers having linear unbranched alkyl
groups do not exhibit the hypochlorite stability that results
when the branched chain isomers are used. A typical branched
chain sulfonate is a highly branched dodecyl benzene sodium
sulfonate.
The bleaching agent is sodium hypochlorite.
17,790A-F -2-
7'~37(~
If maximum hypochlorite stability is to be attained,
the formulations should be at a high pH, preferably of from
about 11.0 to 13Ø That is easily achieved by including a
water soluble alkaline builder into the composition. Pre-
ferred alkaline builders are the inorganic salts, such as
the alkali metal carbonates (e.gO sodium carbonate), the
alkali metal phosphates (e.g. trisodium phosphate), and the
alkali metal silicates (e.g. sodium metasilicate). Any suit-
able base, such as sodium and potassium hydroxide may also
be employed. Combinations of salts and bases may be used.
The amounts of the ingredients are chosen to give `
the desired levels of detergency, bleaching and stability.
Those amounts may be varied within generally wide limits as
hereinafter qualified. The amount of active cleaning,
bleaching and stabilizing ingredients will usually not
exceed about 10 weight percent of the solution and prefer-
ably will be in the range of about 1 to 5 weight percent for
a general household cleaning formulation. In that instance,
the detergent will be in a concentration of from about 0.5
to 3 weight percent, the hypochlorite in the range of from
about 0.25 to 1.0 weight percent and the alkaline builder
in an amount sufficient to raise the pH to 11.0 or above.
The basic guidelines for preparing the compositions
are that the detergent be present in excess over the hypo-
chlorite and that the hypochlorite bleaching agent not
exceed about 1.0 weight percent of the solution. Thus it
will be apparent that the detergent may be present in a
concentration of from about 0.5 up to its limit of solu-
bility while retaining a fluid state.
17,790A-F _3-
1~7737~
Other ingredients may be added to the solutions
for desired special purposes. For example, inorganic
thickening agents may be included to enhance the utility of
the cleaner on vertical surfaces. Typical of such colloids
are the inorganic clays. Such materials are readily avail-
able. One preferred thickener is a synthetic clay containing
hydrated sodium magnesium silicates. Organic colloids are
generally not useful since they tend to destabilize the
bleach.
Minor amounts of, for example, up to about 1 weight
percent of the formulation, of bleach stable organic solvents
may also be included to enhance the cleaning effectiveness of
the composition. By bleach stable is meant that the solvent
does not react with or otherwise adversely affect the stabil-
ity of the hypochlorite. Thus, solvents, such as alcohols,
ketones, or alkanolamines will be inopposite. Petroleum
distillates, such as kerosene and naphtha, are typical of
useful solvents.
Additives, such as the above-described thickeners
and solvents, will frequently be insoluble in water with the
result that the cleaning formulation will be a dispersion of
the additive in the water. So long as the additiYes are
uniformly dispersed, they will not adversely affect the
results obtained.
Fragrances may also be included in the formulations
for their intended purpose. It is necessary that any such
fragrance be stable to the bleach. That can be determined
by simple prel:iminary experiment.
The :invention is illustrated by the following
examples.
17,790A-F ~4~
737(~
EXP~LE 1
Formulations were prepared containing 0.75 weight
percent sodium hypochlorite, 2.8 weight percent trisodium
phosphate, and 1.5 weight percent active surfactant with
94.95 weight percent deionized water.
Separate samples of each formulation were aged at
three temperatures. The hypochlorite concentration was
determined by titrating the free iodine released from RI
with sodium thiosulfate. The rate at which the bleach disap-
lQ peared was used to extrapolate the number of days when half
o~ the bleach was used up - the half-life - which is temper-
ature dependent.
The results are shown in the following table.
17,790A-F -5-
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17, 790A-F -6-
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1~ 7737~
As a comparison, an aqueous solution of 0.75 weight
sodium hypochlorite had a half-life at 120F of 253 days
and a 5 weight percent sodium hypochlorite solution had a
half-life at 120F of 40 days.
EXAMPLE 2
Aqueous solutions of 1.5 weight percent sodium
lauryl sulfate with 0.57 weight percent sodium hypochlorite
(containing about 0.04 percent sodium hydroxide) and various
alkaline builders were prepared and tested for half-life as
in Example 1. The results are shown in the following
Table II.
TABLE II
Builder % Conc 69-73F 90F 120F
None 312 86 15
Trisodium Phosphate ~.8 1432 469 58
Sodium Carbonate 2.0 139 28
Sodium Metasilicate 1.0 2382 628 91
Sodium Hydroxide 0.32 85
Sodium Hydroxide 0.41 103
Sodium Hydroxide 0.46 114
EXAMPLE 3
The strong influence of the alkaline builder on
the stability of the detergent compositions was also deter-
mined using different emulsifiers with and without the
builder. The results are shown in the following table.
17,790A-F -7-
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17, 790A-F -8-
. . - .
10'77370
EXAMPLE 4
Thickened formulations were prepared from 1.5
weight percent sodium lauryl sulfate, 0.32 weight percent
sodium hydroxide, 0.57 weight percent sodium hypochlorite,
2.0 weight percent of a synthetic clay containing hydrated
sodium magnesium silicates, and 95.61 weight percent water.
A similar composition was prepared from 3.0 weight
percent Macaloid Clay, 94.61 weight percent water and all
other ingredients in the same amounts.
The compositions were stable and showed outstanding
cleaning efficiency.
EXAMPLE 5
A composition having reduced aluminum corrosion
was prepared similar to the first formulation of Example 4
except it contained 0.12 weight percent sodium hydroxide,
0.58 weight percent sodium metasilicate, 0.55 weight percent
sodium hypochlorite and 95.25 weight percent water.
EXAMPLE ~
Detergent formulations were prepared using differ-
ent detergents. In all cases the formulations contained 0.5
weight percent sodium hypochlorite, 0.3 weight percent
sodium hydroxide and 1 weight percant active surfactant.
The results are shown in the following table.
17,790A-F -9-
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17,790A-F -10-
