CA1077370A - Stable cleaning agents of hypochlorite bleach and detergent - Google Patents

Abstract

ABSTRACT

A cleaning formulation for cleaning stubborn stains comprises an aqueous solution of (a) an alkali metal alkyl sulfate wherein the alkyl is a straight chain of from about 6 to 20 carbon atoms, (b) a branched chain alkyl aryl sulfonate wherein the alkyl group contains from 8 to 18 carbon atoms or (c) mixtures thereof as a detergent with less than one weight percent of sodium hypochlorite and with an amount of an alkaline builder to maintain the pH above about 11Ø

Description

~(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.

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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.

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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.

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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.

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 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.

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10'77370 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.

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.

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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 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 wherein said alkyl group is a straight chain moiety containing 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 of said formulation of sodium hypochlorite and (3) a sufficient amount of a water soluble alkaline builder to maintain the pH of said formu-lation at above about 11.0 and wherein said detergent is present in excess over the hypochlorite.

2. The cleaning formulation of Claim 1 wherein said synthetic detergent is sodium lauryl sulfate.

3. The cleaning formulation of Claim 1 wherein said alkaline builder is sodium hydroxide.

4. The cleaning formulation of Claim 1 wherein said alkaline builder is trisodium phosphate.

5. The cleaning formulation of Claim 1 wherein said alkaline builder is sodium metasilicate.

6. The cleaning formulation of Claim 1 consisting essentially of at least 95 weight percent water, from about 0.5 to 3 weight percent synthetic detergent, from about 0.3 to 1 weight percent sodium hypochlorite, and sufficient alkaline builder to establish the pH of said formulation at from about 11.0 to 13.0

7. The cleaning formulation of Claim 1 containing in addition a thickening amount of an inorganic thickener.

8. The cleaning formulation of Claim 7 wherein said inorganic thickener is a water swellable clay.