WO2003074643A1

WO2003074643A1 - Acidic cleaning compositions

Info

Publication number: WO2003074643A1
Application number: PCT/GB2003/000804
Authority: WO
Inventors: Peter Woodhead
Original assignee: Selden Research Limited
Priority date: 2002-03-01
Filing date: 2003-02-27
Publication date: 2003-09-12
Also published as: AU2003209998A1; EP1481047A1; GB0204781D0

Abstract

A thickened acidic cleaning composition comprising an acidic component, at least one amine oxide of general formula (I) and at least one amphoteric surfactant wherein R1, R2, and R3 are any alkyl, alkoxylated or aryl group.

Description

ACIDIC CLEANING COMPOSITIONS

The invention relates to cleaning products and in particular thickened acidic, cleaning products.

Thickened acidic cleaning products have been commercially available for many years. Typically they are used in the field of toilet bowl cleaning where the viscosity gives the product extended contact time as it runs down the vertical walls of the toilet bowl. Generally, toilet bowl cleaners contain in the region of 10% acid, usually made up of either a mineral acid, such a.s hydrochloric, sulphamic or phosphoric acid; or an organic acid such as citric, oxalic, lactic or maleic acid. Thickened acidic cleaning products have also found utility as all purpose washroom cleaners which are milder in pH than the aforesaid toilet cleaning products, typically buffered to between pH 2.0 and pH 5.5, and often containing a biocide for general disinfection.

Furthermore, thickened acidic cleaning products have been used for derusting vertical surfaces or cleaning areas with a high level of metallic soiling such as removing brake dust from wheels or railway carriages.

In any of the aforesaid applications the thickened acidic products are typically applied as a thick liquid or as a foam via an aerosol device with or without dilution or a foaming lance. Traditionally the thickening agent of the aforesaid cleaning products have been alkyl phenyl ethoxylates (APE's), whilst these afford suitable viscosity and detergency to the products their use has been recently restricted, particularly in Europe, due to their detrimental effects on the environment so much so that OSPAR (the Oslo and Paris Convention) has recommended a ban on their use. Consequently, the industry has sought less damaging alternatives although there has proven to be a very limited supply of suitable agents.

The most common replacements for APE's in other cleaning applications are alcohol ethoxylates but these have insufficient thickening properties to make them a commercially viable alternative. Naturally derived polymers such as xanthan gum and hydroxy ethyl cellulose (BDEC) have been used but are limited by their relative instability in acidic conditions leading to a drop in viscosity over time, and their cost, since the formulated product still requires additional agents for detergency and perfume solubility. A good review of surfactant based thickening systems is given by Ben Milwidsky in the April 1990 edition of HAPPI. One of the more successful systems mentioned i this review is using a C₁₈ alkyl amine ethoxylate in combination with an alcohol ethoxylate and cumene sulphonate. This gives a viscous stable product but suffers from a poor odour due to the requirement to use a relatively long chain amine. A similar system is mentioned in EP 0265979 which uses a long chain (Ciβ or greater) alkyl amine derivative, such as tallow trimethyl ammonium chloride in combination with an organic aryl sulphonate, such as sodium xylene sulphonate. Again this system can be limited by poor odour and pseudoplastic rheology which gives undesirable product aesthetics. Similar results can be achieved using other long chain amine derivatives such alkyl amine oxide ethoxylates, for example Aromox T12 produced by Akzo Nobel, or amphoteric surfactants derived from long chain amines such as Mona AT1200 produced by Uniqema. However, these systems based on longer chain amines suffer the same problems of poor odour and, when used alone, pseudoplastic rheology. Other disadvantages of using the long chain amine derivatives is the frequent need to add an organic aryl sulphate. Whilst this material is suitable for use in normal toilet bowl cleaning it is not suitable for use with certain cationic additives such as quaternary ammonium biocides. This limits the use of these systems in milder washroom cleaners where the addition of a biocide is desirable.

Medium chain length alkyl amine oxides (typically Cιo-C₁₄) have been used predominantly for thickening hypochlorite containing cleaning solutions for many years. Although these alkyl amine oxides and their ethoxylates have been shown to exhibit thickening effects in acidic conditions, the amounts required to achieve this effect are uneconomical for such a competitive market as toilet bowl cleaning due to the relatively high market price of the said alkyl amine oxides and their ethoxylates. It has been shown that amphoteric surfactants exhibit synergistic thickening effects in conjunction with anionic surfactants in neutral or alkaline pH. However, the more commonly used and economical anionic surfactants such as sodium lauryl sulphate and sodium lauryl ether sulphate, are unstable in acidic conditions and so are not suitable for use as thickening agents in acids. It is desirable therefore to produce a stable, economical, odourless thickened acidic cleaning product with good detergency containing an environmentally acceptable thickening agent. Li particular, such a system should perform well over a wide range of acidic conditions and be suitable for use in conjunction with other cationic active ingredients to widen the range of formulated products available. According to the present invention there is provided a thickened acidic cleaning composition comprising an acidic component, at least one amine oxide of general formula 1 and at least one amphoteric surfactant

General Formula 1

wherein Ri, R₂ and R₃ are any alkyl, alkoxylated or aryl group. It has been found that suitable amine oxides and amphoteric surfactants exhibit synergistic thickening properties in a wide range of acidic conditions.

Advantageously, the synergistic thickening enables shorter chain amine oxides to be used than in the aforementioned prior art systems, typically a Cι amine oxide can be used. Since Cι amine oxides have no appreciable odour their use does not restrict the fragrance of the product as masking of the amine oxide odour is not a consideration. Furthermore, the use of these materials does not interfere with the addition of other cationic additives such as bϊocides, corrosion inhibitors and water displacing agents.

A surprising additional benefit of this system is that in more acidic conditions, for example below pH 5, the formulation exhibits some biocidal properties such that the addition of further biocide(s) is not always required.

Conveniently, the composition of the present invention may be supplied as a concentrated liquid requiring dilution prior to use, a dilute ready to use liquid, an aerosol product or otherwise. The composition of the present invention is suitable for use in a wide variety of applications for example, descaling and derusting products general washroom and toilet bowl cleaning products. The thickness and acidity of the composition can be adjusted to suit the application of the composition, but will typically range from lOCps to 3000Cps. (viscosity is measured at 20°C using a Brookfield viscometer).

The amine oxide shall preferably comprise alkyl groups wherein Rι=Cι to C₂₂

More preferably, the amine oxide shall comprise alkyl groups wherein Rι=Cιo

Most preferably the amine oxide shall comprise alkyl groups wherein _I-C_H and R₂=R₃=Me, that is myristyl amine oxide.

The amine oxide shall constitute from 0.2 to 20% by weight, and preferably from 0.2 to 10% by weight of the total composition. However, in order to achieve sufficient thickening of the composition the amine oxide preferably constitutes from 0.5 to 5% by weight of the total composition of the present invention.

Typically, an amine oxide content of greater than 5% by weight of the composition is needed where viscosity upon dilution is required. Suitable amphoteric surfactants are typically derived from secondary and/or tertiary amines where the alkyl groups can be straight or branched alkyl chains bearing between 1 and 22 carbon atoms. Furthermore, the alkyl chains may also bear additional functional groups, for example amido groups.

The nitrogen of the amphoteric surfactant is preferably in a cationic state although there is no limit to the number of cationic charges the said amphoteric surfactant may bear.

At least^' one of the said alkyl groups must contain an ionisable head group which may adopt a negative charge. Suitable examples include carboxylate, sulphate, sulphonate, phosphate, phosphonate, succinate or sulphosuccinate. The amphoteric surfactant shall preferably, be chosen from betaines, sultaines, hydroxysultaines, iminopropionates and iminodipropionates. The most preferred amphoteric surfactant being an alkylamidopropyl betaine, for example cocamidopropyl betaine. The amphoteric surfactant shall constitute from 0.1 to 15% by weight of the total composition, preferably from 0.1 to 10% by weight and most preferably from 0.2 to 5% by weight of the total composition.

The acidic component comprises at least one mineral acid and/or at least one organic acid, and/or at least one buffer and mixtures thereof. Suitable mineral acids, which may be used alone or in combination, include nitric, phosphoric, sulphamic, sulphuric and hydrochloric acid.

Suitable organic acids, which may be used alone or in combination, include citric, formic, lactic and maleic acid.

Where a buffer is used, the buffer is prepared from one or more mineral and/or organic acids or any acidic product which is partially neutralised using an alkali, examples of which include, sodium hydroxide, tetrasodium nitrilo triacetate and tetra sodium ethylene diamine tetraacetate. Preferred sources of alkali are mono-, di- and tri-alkanolamine.

Where an acid is used in preference to a buffer, a milder mineral acid is preferred, for example, sulphamic and/or phosphoric acid.

Generally, the acidic component shall constitute from 0.1 to 75% by weight of the total composition of the present invention.

However, the level at which the acidic component is included in the composition depends upon the use to which the composition is to be put. Where the composition is to be applied as a descaling product, the acidic component shall preferably constitute more than 1% by weight of the total composition of the present invention.

Where the composition is to be applied as a toilet cleaning product, the acidic component shall preferably constitute from 0.4 to 40% by weight and more preferably from 5 to 20% by weight of the total composition of the present invention.

Where the composition is to be used for derusting purposes, the acidic component shall preferably constitute about 30% by weight of the total composition of the present invention. Where a buffer is used in preference to an acid, said buffer preferably constitutes from 0.5 to 5% by weight and more preferably around 2% by weight of the total composition of the present invention.

The pH of the composition differs depending on the use to which the composition is to be put, but typically does not exceed 5.5. Alternatively, where a particularly mild formulation is required the natural acidity of one or more of the components may be sufficient to lower the pH below 7 i.e. acidic. For example, where the product is being used for general hard surface washing it may be preferable to have a pH closer to neutral so further addition of acid may not be required if the formula naturally has a pH below 7. Electrolyte is often added to raise the viscosity of the formulation. There are several sources of electrolyte. Organic electrolytes, such as the anionic aryl sulphonates used by Akzo, raise the viscosity at relatively low addition rates. Inorganic electrolytes such as sodium chloride, are also suitable and have the benefit of being economical and compatible with optional additional cationic ingredients. Other electrolytes can be prepared in situ, examples of which include aforementioned buffers.

Inclusion rates of the electrolyte are only limited by the solubility of the electrolyte. Some formulations may naturally contain a sufficient amount and not require any further additions.

Where the biocidal efficacy resulting from the synergistic interaction of the amine oxide and the amphoteric surfactant is insufficient for the use to which the composition is to be put, biocides may be optionally added.

Typically suitable biocides are those of the quaternary ammonium type. Since such biocides enhance the existing biocidal nature of the composition only small quantities are required, preferably, less than 3% by weight of the total composition.

Any cationic biocide is suitable for inclusion into the composition, but benzalkonium chloride is the biocide of choice.

Furthermore, additional constituents may be added to the composition of the present invention in order to improve the cleaning or foaming properties of the composition, to deposit an active ingredient onto the surface such as a water displacing agent or to adjust the rheological characteristics of the composition. These include dyes, perfumes, corrosion inhibitors, solvents, surfactants, biocides, associative thickeners and mixtures thereof. Careful selection of these ingredients is required since their inclusion is limited only by their compatability with the essential features of the composition.

Acid stable dyes are added to the composition at levels not exceeding 0.5% by weight of the total composition. Perfumes are added to the composition at levels not exceeding 2% by weight of the total composition. Suitable corrosion inhibitors are those of the Armohib (RTM) range available from Akzo Nobel Chemicals and are added to the composition at levels not exceeding 1.0% by weight of the total composition.

Additional surfactants may be added in order to boost the detergency, alter the foaming properties and alter the rheology of the composition. Typically additional surfactants are of a non-ionic type although other types of surfactants are equally suitable. Examples of suitable additional surfactants include alcohol ethoxylates, alkyl polyglucosides and alkyl amides and their ethoxylates.

Solvents may be added in order to enhance the degreasing properties of the composition, for example glycol ethers and terpenes.

It is to be understood that all percentage values are measured by weight, and are relative to the total composition whether the composition is in a concentrated form or a dilute ready-to-use form.

The invention will now be described further by reference to the following specific examples:-

NB: Monoethanolamine is added to the formulation D as a neutralising agent in a amount to make the pH of the formulation pH 4.0.

Formulation C is an example of an aerosol product.

Formulation E is an example of a concentrated liquid product which is diluted in the ratio 1 part product to 20 parts water prior to use.

Formulation F has a natural pH of 6.9.

Claims

1. A thickened acidic cleaning composition comprising an acidic component, at least one amine oxide of general formula 1, and at least one amphoteric surfactant

General Formula 1 wherein Ri, R₂ and R₃ are any alkyl, alkoxylated or aryl group.

2. A thickened acidic cleaning composition according to claim 1 wherein

3. A thickened acidic cleamng composition according to claim 1 wherein 4. A thickened acidic cleaning composition according to claim 1 wherein

C ^•22-

5. A thickened acidic cleaning composition according to claim 1 wherein Rι=Cιo

6. A thickened acidic cleaning composition according to claim 1 wherein R^C_M.

7. A thickened acidic cleaning composition according to any preceding claim wherein the amine oxide constitutes from 0.2 to 20% by weight of the total composition.

8. A thickened acidic cleaning composition according to claim 7 wherein the amine oxide constitutes from 0.2'to 10% by weight of the total composition.

9. A thickened acidic cleaning composition according to claim 7 wherein the amine oxide constitutes from 0.5 to 5% by weight of the total composition.

10. A thickened acidic cleaning composition according to claim 1 wherein the amphoteric surfactant is derived from a secondary or tertiary amine where the alkyl groups can be straight or branched alkyl chains bearing between 1 and 22 carbon atoms.

11. A thickened acidic cleaning composition according to claim 10 wherein the amphoteric surfactant contains a cationic nitrogen.

12. A thickened acidic cleaning composition according to claim 10 or 11 wherein at least one of the alkyl groups of the amphoteric surfactant has an ionisable head group.

13. A thickened acidic cleaning composition according to any of claims 10 to 12 wherein the amphoteric surfactant is a betaine.

14. A thickened acidic cleaning composition according to claim 13 wherein the amphoteric surfactant is an alkyl amido-propyl betaine.

15. A thickened acidic cleaning composition according to any of claims 10 to 14 wherein the amphoteric surfactant constitutes from 0.1 to 15% by weight of the total composition.

16. A thickened acidic cleaning composition according to claim 15 wherein the amphoteric surfactant constitutes from 0.1 to 10% by weight of the total composition.

17. A thickened acidic cleaning composition according to claim 15 wherein the amphoteric surfactant constitutes from 0.2 to 5% by weight of the total composition.

18. A thickened acidic cleaning composition according to claim 1 wherein the acidic component comprises one or more of: at least one mineral acid, at least one organic acid, and at least one buffer. -

19. A thickened acidic cleamng composition according to claim 18 wherein the mineral acid is selected from nitric, phosphoric, sulphamic, sulphuric and hydrochloric acid.

20. A thickened acidic cleaning composition according to claim 18 wherein the organic acid is selected from citric, formic, lactic and maleic acid.

21. A thickened acidic cleaning composition according to claim 18 wherein the buffer is prepared from one or more of: at least one mineral acid, and at least one organic acid, said acid be partially neutralised using alkali.

22. A thickened acidic cleaning composition according to claim 21 wherein the alkali is selected from one of more of: mono-, di-, and triethaholamine.

23. A thickened acidic cleaning composition according to any of claims 18 to 22 wherein the acidic component constitutes from 0.1 to 60% by weight of the total composition.

24. A thickened acidic cleaning composition according to claim 18, 21 or 22 wherein the buffer constitutes from 0.5 to 5% by weight of the total composition.

25. A thickened acidic cleaning composition according to claim 24 wherein the buffer constitutes 2% by weight of the total composition.

26. A thickened acidic cleaning composition according to any preceding claim wherein an electrolyte is added.

27. A thickened acidic cleaning composition according to claim 26 wherein the electrolyte .is selected from organic electrolytes, inorganic electrolytes and mixtures thereof.

28. A thickened acidic cleaning composition according to any preceding claim wherein a biocide is added.

29. A thickened acidic cleaning composition according to claim 28 wherein the biocide is cationic.

30. A thickened acidic cleaning composition according to claim 28 or claim 29 wherein the biocide is benzalkonium chloride.

31. A thickened acidic cleaning composition according to any of claims 28 to 30 wherein the biocide constitutes less than 3% by weight of the total composition.

32. A thickened acidic cleaning composition according to any preceding claim containing any one or more additional constituent selected from acid stable dyes, perfumes, corrosion inhibitors, solvents, additional surfactants, water repellents, biocides and associative thickeners.

33. A thickened acidic cleaning composition according to claim 32 containing at least one acid stable dye which is added in proportions not exceeding 0.5% by weight of the total composition.

34. A thickened acidic cleaning composition according to claim 32 containing at least one corrosion inhibitor which is added_. in proportions not exceeding 0.1% by weight of the total composition.

35. A thickened acidic cleaning composition according to claim 32 containing at least one additional surfactant which is nonionic.

36. A thickened acidic cleaning composition according to claim 35 wherein one or more non-ionic surfactant is selected from an alcohol ethoxylate, an alkyl polyglucoside, an alkyl amide or an alkyl amide ethoxylate.

37. A thickened acidic cleaning composition according to claim 35 or 36 wherein the additional surfactant is added at proportions not exceeding 10% by weight of the total composition.

38. A thickened acidic cleaning composition according to claim 32 containing at least one additional biocide which constitute less than 2% by weight of the total composition.

39. A thickened acidic cleaning composition according to claim 32, wherein the water repellent constitutes less than 5% by weight of the total composition.

40. A thickened acidic cleaning composition according to formulation A, B, C, D, E and F as described herein.