EP0033601A1

EP0033601A1 - Alkaline cleaning compositions

Info

Publication number: EP0033601A1
Application number: EP81300199A
Authority: EP
Inventors: Alexander Ewing Harding
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1980-01-17
Filing date: 1981-01-16
Publication date: 1981-08-12
Also published as: GB2067588A

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

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.
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.
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.

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

Cleaning compositions were made up according to the following table:
A number of prior art formulations approximately according to the following table were prepared:
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

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.