GB2073233A - Cleaning compositions - Google Patents

Abstract

A composition for use as a cleaning composition for sanitary installations comprising an acid or an acid salt and a surface active agent, the composition having a reaction rate as hereinbefore described with calcium carbonate of at least 5% weight loss and having a corrosion rate as hereinbefore defined of less than 0.01 mm per year. The composition is preferably an aqueous solution having a pH of 1 to 4 and a viscosity of 80 to 340 centipoises.

Description

SPECIFICATION Cleaning compositions This invention relates to cleaning compositions and more particularly concerns compositions which are suitable for cleaning sanitary installations such as lavatory bowls.

It is known to use compositions based on hydrochloric acid and sulphuric acid for these purposes, as these acids are available commercially providing for cost viable formulations.

In order to improve adhesion to inclined surfaces on sanitary installations, it is also known to include a thickening agent in the composition.

The use of such thickening agents however, tends to inhibit the de-scaling and cleaning effect considerably, especially those containing hydrochloric acid.

The use of mineral acids, such as hydrochloric or sulphuric, has the disadvantage that a highly corrosive product is produced and is therefore not only unpleasant to handle but also has an adverse effect on stainless steel and chromium plate of the types commonly employed in public and industrial company sanitary systems.

Compositions based on acids other than hydrochloric or sulphuric acids, e.g. phosphoric acid, have been used but these acids tend to have an inferior cleaning and de-scaling effect.

We have now produced a cleaning composition which has been found to be more effective in cleaning and de-scaling sanitary installations such as lavatory bowls.

According to the present invention we provide a composition for use as a cleaning composition for sanitary installations comprising an acid or an acid salt and a surface active agent, the composition having a reaction rate as hereinafter described with calcium carbonate of at least 5% weight loss and having a corrosion rate as hereinafter defined of less than 0.01 mm per year.

Preferably the composition is an aqueous solution have a pH of 1 to 4.

Advantageously the viscosity of the composition is 80 to 340 centipoises measured as hereinafter described.

In a preferred composition the reaction rate with calcium carbonate is at least 10% weight loss, more preferably at least 12% weight loss.

It is also preferred that the composition has a corrosion rate of less than 0.05 mm per year, more preferably less than 0.03 mm per year.

Viscosity, in this specification is quoted in centipoises and is measured using a Brookfield RVT Viscometer at 200C using a No. 1 or No. 2 spindle at 20 r.p.m.

The rate of reaction used herein is obtained by measuring the evolution of carbon dioxide from a marble cube by the following method: A 1 cm marble cube weighing between 2.71 and 2.72 grams, was taken. This was placed on a watch glass on top of a 150 ml squat beaker containing 50 mls of product at 200 C. This gave the initial weight. The marble cube was then added to the product and the weight loss as evolution of carbon dioxide measured on a 4 place analytical balance every 5 minutes over a 20 minute period whilst the beaker remained covered with the watch glass.

The weight of carbon dioxide evolved was converted to weight of calcium carbonate (marble) dissolved using the fact that 0.44 grams of carbon dioxide is evolved for each gram of marble dissolved and quoted as a percentage weight loss.

Corrosion rate as quoted herein is quoted against stainless steel using a thickness loss method. A plate of the stainless steel under test is disposed in the composition for a known period of time and the average loss in thickness of the plate measured. Typical types of stainless steel used for sanitary installations are B.S. 31 6 and 304.

Preferably, the solution exhibits clarity at least in the temperature range 50 to 400C.

The acid may be an inorganic acid or an organic acid. Examples of suitable inorganic acids are orthophosphoric and sulphamic acids. Examples of organic acids are carboxylic acids, particularly dicarboxylic acids and tricarboxylic acids and especially hydroxy and dihydroxy dicarboxylic and tricarboxylic acids. Mixtures of acids may, of course, be used if desired.

The acid will generally be present in a proportion such as to achieve the desired cleaning and de-scaling effect but insufficient to provide an unacceptable corrosion level e.g. when used on stainless steel or chromium plate fittings.

Generally this will be a proportion of less than 50% by weight based on the total weight of the composition, preferably 4 to 40% and more preferably 5 to 25%.

Where orthophosphoric acid is employed it is normally present in an amount of 4% to 40% based on the total weight of the composition or sulphamic acid in an amount up to 10% based on the total weight of the composition.

The surface active agent may be a sulphonate such as an alkyl sulphonate or an alkenyl sulphonate; an alkenyl aryl sulphonic acid or a salt thereof; or preferably, an alkyl aryl sulphonic acid or a salt thereof, such as a sodium salt. The alkyl or alkenyl groups may be linear or non-linear.

Higher alkyl benzene sulphonic acids are particularly suitable, especially dodecyl benzene sulphonic acid and dodecylated oxydibenzene disulphonic acid, or salts thereof.

The amount of surface active agent present will generally be such as to provide the desired viscosity of the resulting composition and this will usually be an amount up to 10% by weight based on the total weight of the composition. The preferred amount is 4% to 8% more preferably 4.5% to 6.5%.

The composition may include one or more additives to improve its effectiveness and/or consumer acceptability. Thus it is envisaged that one or more perfumes, dyes, colouring agents, bactericides, corrosion inhibitors or other additives may be included.

The use of a corrosion inhibitor will depend to a large extent on the type and concentration of acid or acid mixture employed in the composition.

Thus, certain acids and acid mixtures exhibit a satisfactorily low corrosion effect even without an inhibitor whilst other acids do not but even where the corrosion effects are satisfactorily low it may stiil be preferable to use an inhibitor. A preferred inhibitor is available commercially under the trade name "DUOTERIC S.N." The composition may also include a thickener although the surface active agent will usually be present in an amount sufficient to give the required viscosity. Examples of suitable thickeners commercially available are Xanthan gums.

Reference is now made to one specific composition which we have found to be satisfactory for use as a toilet cleaner. All quantities are quoted as percentages by weight based on the total weight of the composition.

12% orthophosphoric acid 4.5% sulphamic acid 4.5 dodecyl benzene sulphonic acid (96% active commercial grade) 0.2% perfume 25 ppm water soluble blue dye The above composition had a viscosity of 92 centipoises measured using the method described above.

The rate of reaction was measured using the method described above and the average weight loss was 12. 1% using a 1 cm marble cube. As a comparison a commercially available thickened cleaner based on hydrochloric acid produced a weight loss of 2.9% under identical conditions.

The corrosion rate was about 0.005 mm per year on stainless steels B.S. 316 and 304.

The compositions of the present invention are particularly suitable for use as cleaners for sanitary installations as they are effective in removing scale and also do not exhibit unsatisfactory corrosion towards stainless steel. The clear solutions give consumer appeal whilst the viscosity provides for adherence to inclined surfaces which is important particularly where scale is to be removed from such surfaces.

Claims (14)

1. A composition for use as a cleaning composition for sanitary installations comprising an acid or an acid salt and a surface active agent, the composition having a reaction rate as hereinbefore described with calcium carbonate of at least 5% weight loss and having a corrosion rate as hereinbefore defined of less than 0.01 mm per year.

2. A composition according to Claim 1 in which the composition is an aqueous solution having a pH of 1 to 4.

3. A composition according to Claim 1 or 2 in which the viscosity of the composition is 80 to 340 centipoises measured as hereinbefore described.

4. A composition according to any of Claims 1 to 3 in which the weight loss is at least 10%.

5. A composition according to any of Claims 1 to 3 in which the weight loss is at least 12%.

6. A composition according to any of Claims 1 to 5 in which the corrosion rate is less than 0.05 mm per year.

7. A composition according to any of Claims 1 to 5 in which the corrosion rate is less than0.03 mm per year.

8. A composition according to any of Claims 1 to 7 in which the acid is orthophosphoric acid, sulphamic acid or a mixture thereof.

9. A composition according to Claim 8 in which the amount of orthophosphoric acid employed is 4% to 40% based on the total weight of the composition.

10. A composition according to Claim 8 or 9 in the amount of sulphamic acid present is up to 10% based on the total weight of the composition.

1 A composition according to any of Claims 1 to 10 in which the surface active agent is an alkenyl sulphonate, an alkenyl aryl sulphonic acid or a salt thereof.

12. A composition according to Claim 11 in which the surface active agent is dodecyl benzene sulphonic acid.

13. A composition according to any of Claims 1 to 12 which includes a corrosion inhibitor.

14. A composition useful as a cleaning composition for sanitary installations substantially as herein described particularly in the example.