Alkaline cleaning compositions

Abstract

 A cleaning composition, particularly for cleaning industrial ovens, contains an aqueous base, from 1% to 6% of a nonionic surfactant such as a polyoxyalkylene alkyl ether, from 1% to 40% of an alkali such as caustic soda and from 5% to 20% of a solvent such as a glycol ether. Hydrotropes, such as sodium xylene sulphonate and thickeners such as hydroxyethyl cellulose may also be present.

Description

[0001] The present invention relates to alkaline cleaning compositions, particularly aqueous alkaline compositions adapted for use in non-aerosol form and suitable for cleaning hard surfaces such as ovens and the like.

[0002] It is known from British Patent Specification 1 297 782 to use, as oven cleaning compositions, aqueous alkali compositions which contain caustic alkali, an alkali-stable organic detergent active compound, and an aliphatic monohydric alcohol and which are adapted for use in aerosol form. It is also known from United States Patent Sepcification 3 829 387 to use, as an aerosol oven cleaning composition, an aqueous alkali composition containing caustic alkali, a glycol ether and a non-ionic detergent active compound.

[0003] We have now surprisingly discovered that particularly good cleaning results can be achieved with a cleaning composition comprising an aqueous base containing:

( i) from about 1% to about 6% by weight of a non-ionic surfactant;

(ii) from about 1% to about 40% by weight of an alkali; and

(iii) from about 5% to about 20% by weight of a solvent.

[0004] The non-ionic surfactant is preferably a polyoxyalkylene alkyl ether such as the "Brij"-type non-ionics. Particularly suitable examples are Brij 35 (polyoxyethylene (23) lauryl ether) and Brij 78 (polyoxyethylene(₂₀) stearyl ether). The quantity of the non-ionic surfactant may be from about 1.5% to 2.5%, preferably about 2% by weight.

[0005] The alkali is preferably a caustic alkali such as sodium hydroxide or potassium hydroxide. Alternatively silicates such as potassium silicate with a K₂0:Si0₂ weight ratio of 1:2 to 2:1. Further examples of suitable alkali materials are guanidine (formed from guanidine hydrochloride and sodium hydroxide)and mono-,di- and trialkanolamines. The amount of alkali present is preferably from about 1 to about 10% by weight in the case of caustic alkalis and from about 3 to about 30% by weight in the case of an alkali metal silicate. Most preferred ranges are from about 3 to 6% by weight and from about 4 to 10% by weight respectively.

[0006] The solvent is preferably a high boiling point solvent (i.e. having a boiling point over about 120°C). The preferred solvents are: glycol ethers such as butyl cellusolve, methyl, ethyl or butyl carbitol; pentaerythritol propane 1,2-diol; propylene glycol; and dioxitol. The solvent is preferably present in the amount of from about 5% to about 15%, most preferably about 10% by weight.

[0007] Other ingredients may be present in the compositions of the invention..A hydrotrope may be added up to an amount of about 18% by weight, preferably from about 6% to 12% by weight. The hydrotrope may be selected from alkali metal aryl sulphonates, such as sodium xylene sulphonate, the latter also aiding soil penetration by the composition. A thickening agent may also be present, in an amount up to about 2% by weight, preferably about 0.4% by weight. The thickening agent enables the product to cling better to vertical surfaces and reduces mist on spraying the neat product. Suitable thickening agents include hydroxyethyl cellulose (Natrosol - Registered Trade Mark), lauryl alcohol, stearyl alcohol, magnesium sulphate, sodium carbonate and sodium chloride, hydroxypropylcellulose (Klucel - Registered Trade Mark), acrylate-methacrylate polymer (Latekoll - Registered Trade Mark) or mixtures of these with hydroxyethyl celluloses. The preferred amount of thickening agent is up to about 2% by weight in the case of an organic thickener, more preferably about 0.4% by weight and up to 6% by weight in the case of an inorganic thickener, more preferably about 1 to 3% by weight.

[0008] The preferred thickener is a cellulose based nonionic polymer especially the sterically hindered natrosol type>. These give much better viscosity stability witn time in these formulations.

[0009] Further optional ingredients in the cleaning compositions of the invention include dyes and humectants.

[0010] The invention will now be illustrated, purely by way of example, with reference to the following nonlimiting examples, in which parts and percentages are by weight, unless otherwise stated.

EXAMPLES 1 TO 4

[0011] Cleaning compositions were made up according to the following table:

[0012] A number of prior art formulations approximately according to the following table were prepared:

[0013] Examples 1 to 4 were compared with the prior art formulations A to G for detergency efficiency. The evaluation was based on the average base reflectance measurements (R 460*) on a number of soiled white test plates. The reflectance measurement on a clean plate was 69.7. The results were as follows:

EXAMPLES 5 TO 13

[0014] The formulations set out in the following table were prepared.

Claims

1. A cleaning composition comprising an aqueous base containing

( i) from about 1% to about 6% by weight of a nonionic surfactant;

( ii) from about 1% to about 40% by weight of an alkali; and

(iii) from about 5% to about 20% by weight of a solvent.