This invention relates to surfactant compositions and to aqueous alkaline hard-surface cleaning or detergent compositions containing such surfactant compositions. Without limitation thereto, the invention particularly relates to detergent compositions, and to separate rinse aid compositions, each for use in the washing, especially the machine washing, of articles of glass plastics or ceramics. The word "ceramics" is used to encompass delft and glazed earthenware and other pottery used for catering and the word "plastics" is used to encompass articles of or containing polymeric materials such as polycarbonates or melamines, used in catering.

Particularly in the case of glass, plastics or ceramics articles, referred to hereafter collectively as "glassware", used to dispense beverages or food it is important that the washed articles should dry without undue and unsightly filming or spotting as a result of the deposition of detergent residues. It is usual to use a separate rinse-aid composition in the rinse cycle of industrial size washing machines, such as those used in commercial catering establishments, and it would be of benefit if this separate addition could be minimised or avoided or if the rinse aid composition could be improved.

It is a further problem that some beverages such as beers or stouts, other ales, or lagers, are traditionally served with a foam "head" which is important to the marketability of the beverages. The stability or size of the head may be adversely affected by detergent or rinse aid residues on the glassware. Some beverages of

these beverages are particularly susceptible to this problem and glassware used to dispense them may be insufficiently rinsed by a rinse cycle which may be considered to be generally effective to remove detergent residues. It would be of benefit to provide cleaning compositions usable without a separate rinse aid addition, or with a reduced rinse aid addition, without causing undue deterioration of the head-retention properties of the beverages, or to provide a rinse aid compositions avoiding or alleviating the problem of insufficient head-retention.

EP-B-0 432 836 describes the use of rinse aid compositions comprising alkyl polyglycosides in the cleaning of plastic articles and, in particular, polycarbonate articles to alleviate the problem of susceptibility to stress cracking in the articles which was caused by contact with prior rinse aid compositions. Ether carboxylate surfactants are not described as rinse aid constituents in this document although certain ether carboxylates are shown to attack polycarbonate. The reduction or omission of a rinse aid step in the washing cycle without undue deterioration in head retention, or the use of a rinse aid which gives an improvement in head retention, are not considered in this document.

According to one aspect the present invention provides an aqueous surfactant composition for use as a rinse-aid composition giving acceptable head retention, the surfactant composition being characterised in that it consists of or comprises an ether carboxylate surfactant or a combination of an ether carboxylate surfactant and an alkyl polyglycoside surfactant.

According to a further aspect the present invention provides an aqueous, alkaline, surfactant-containing, hard-surface cleaning composition, for use in combination with a reduced rinse aid addition, in comparison with normal practice, or without any subsequent rinse aid addition, the composition being characterised in that it comprises an ether carboxylate surfactant or a combination of an ether carboxylate surfactant and an alkyl polyglycoside surfactant.

The invention also provides a process for cleaning a hard surface such as, for example, that of glass, plastic or ceramic articles, by contacting the surface with a cleaning composition provided according to the invention.

The invention also provides a process for rinsing glass or ceramic articles by contacting the articles with a rinse aid composition provided according to the invention.

The term "surfactant" is a term of art which is defined in "Surfactants", Europa Press, 3rd Edition as the contemporary name for surface active agents, the class of chemical products whose molecules are able to modify the properties of a liquid/gas or liquid/liquid interface by lowering the surface, or interfacial, tension with associated changes occurring in other properties such as wetting. Those skilled in the art are in a position to select suitable surfactants and surfactant combinations to attain the purposes of the invention.

EP 457965-A describes a textile washing composition containing an alkyl polyglycoside and an alkanol ether carboxylate together with soap in 5% to 30% by weight of the composition. The problems to which the present invention are directed do not arise and the presence of a substantial soap component would also be inappropriate in a detergent composition requiring rinse performance.

DE 4233385-A describes shampoos and shower gels for personal use based on 5% to 50% by weight of the composition of an anionic surfactant of the sulphate, sulphonate or alkyl phosphate type and containing a polyether carboxylic acid, an amine oxide and an amphoteric surfactant and, optionally, a polyglucoside. Such compositions are not relevant to the field of present invention and would not give the required rinse enhancement.

The ether carboxylate surfactant used according to the invention preferably has the general formula

R' (OC ₂ H ₄ ) _n _0(CH ₂ ) _n _ .COOX wherein

R' represents a straight or branched chain alkyl group containing from 5 to 9 carbon atoms and preferably from 5 to 8 carbon atoms, for example from 5 to 6 carbon atoms n' represents a number from 2 to 9, preferably from 6 to 8 n'' represents a number from 1 to 3, preferably 1 X ^f represents a hydrogen atom or an alkali metal atom or an alkanolamine group, for example a diethanolamone or triethanolamine group. These compounds are relatively low foaming in aqueous media including aqueous alkaline media.

The alkyl polyglycoside surfactant used according to the invention preferably has the general formula

Zn-O-R wherein "Z" represents a reducing hexose molecule "n" represents a number from 1 to 5 and "R" represents an alkyl group containing up to 18 carbon atoms.

The group R is preferably a straight or branched chain saturated or unsaturated group, suitably obtained from naturally occurring fatty acids. Particularly preferably the group R contains at least 8 carbon atoms for example from 8 to 14 carbon atoms.

It is found that the alkyl polyglucosides, in which Z in the above general formula represents a glucose molecule, are particularly effective in use for the purposes of the present invention.

The ether carboxylate surfactant, or the combination of the ether carboxylate surfactant and the alkyl polyglycoside surfactant, is preferably present in the rinse aid or cleaning compositions according to the invention in an effective quantity of from 1% to 20% by weight in total but particularly preferably in at least 4% by weight of the composition. The relative proportion of each of the individual surfactants preferably varies independently from about 1% to about 10% by weight for example, very suitably, from 2% to about 5% by weight of the composition.

While it is preferred that the surfactant content of the compositions of the invention consists of the surfactant or surfactants identified above additional surfactants may be present, if this is not inconsistent in any case with the properties required of the final composition.

It is preferred that the additional surfactants, if present, be limited in total quantity to less than 10% in total by weight of the composition of the invention. As foreshadowed by the references above to published patent specifications it is preferred in the cleaning compositions of the invention that the quantity of any of soap, or of sulphate, sulphonate or alkyl phosphate surfactants, if present, be less than 5%, but particularly preferably less than 2%, for example, very suitably, less than IS. Other surfactants which are preferably absent or may be present but only in the limited quantities indicated above are the ethoxylated nonionics and other anionics, the amphoterics or the cationics.

The rinse aid compositions of the invention essentially comprise one or more surfactants, including the ether carboxylate surfactant, and water but may contain other substances usual in the art such as thickening agents such as, for example acrylate polymers gums or mineral thickening agents, or antifoam agents although, due to the anti-foam characteristics of the ether carboxylates it is preferred that no other anti-foam agent is used.

The aqueous cleaning compositions of the invention are essentially alkaline, for example having a pH of at least 8, suitably at least 9 and up to 14 and the ether carboxylate surfactant is particularly compatible in the context of the invention with such an environment and gives cleaning compositions having low foam characteristics. The required alkalinity may be achieved by the use of strong base such as caustic soda or caustic potash or other suitable material in a suitable quantity. A restricted quantity of a water-compatible organic solvent, such as a polar organic solvent, may be included either as a part of commercial surfactant of other constituents of the composition or added separately. Preferably the quantity of organic solvent is

less than 10 ^s ., particularly preferably less than 5$, by weight of the composition.

The cleaning compositions of the invention preferably also contain one of more sequestrants and/or one or more dispersants. The sequestrants may be selected, for example, from suitable phosphates, phosphonates, heptonates, boroheptonates or gluconates or may be nitrilotriacetic acid (NTA) or ethylenediamine tetraacetic acid (EDTA) and may suitably be present in at least 0.5% and up to 50% by weight of the composition. The dispersants may be selected, for example, from the polyacrylates and may suitably be present in at least 0.5% and up to 5% by weight of the composition.

The cleaning compositions of the invention are particularly suitable for use in the machine washing of wares used in the catering industries and enable a separate rinse aid to be used in a reduced quantity, for example in a quantity not more than 0.2%, or less than 0.1% by volume, or to be omitted. In use to wash glassware used to dispense beers, stouts, lagers or the like the compositions of the invention, either as a cleaning composition having inherent rinse properties or as a separate rinse aid, give enhanced head retention and appearance. The dosage is preferably at least 0.1%, particularly more than 0.2%, and may be up to 1.0% by volume or more.

The invention will now be illustrated by reference to the following non-limiting examples of which Example 5 and 8 are according to the invention and Examples 1 to 4, 6 and 7 and 9 and 10 are not according to the invention but are comparative therewith.

Examples 1 to 7.

The head retention properties of a cleaning composition according to the invention were judged by comparison with similar formulations from which both the ether carboxylate and the polyglycoside had been omitted (the base detergent) or from which either the ether carboxylate or the polyglycoside had been omitted or had been replaced by other non-ionic surfactants. The test used

to judge head retention properties was as follows. A sample of beer is firstly degassed for a minimum of 12 hours. A measured amount of the degassed beer is introduced into a standardised head retention apparatus and foamed with C0 . Head retention is expressed in terms of the time, in seconds, taken for the liquid/foam boundary to move a defined vertical distance. In the examples 5 ml of a 0.4% v/v solution of the composition of the invention or of another, comparative, composition is introduced into the degassed beer and the head retention is measured. Results within 5% of the control result, obtained with no additive, are considered to be excellent and results within 10% acceptable.

The base detergent, with the stated percentages being by weight unless otherwise stated, was: 55.5% water

5.5% NaOH (47% w/w) 25.0% sodium boroheptonate (30% w/w)

2.0% Potassium polyphosphate (50% w/w)

2.0% Phosphinocarboxylic acid (50% w/w) 10.0% Trisodium nitrilotriacetate (31% w/w)

Where surfactants were added these replaced corresponding quantities of water in the base formulation.

The results of the tests were as follows.

Example No. Formulation Head Retention

Tested (sees. )

1 Control - No Detergent 75

2 Base detergent 71

3 Base + 5% w/w Akypo LF4 68

4 Base + 4.5% Berol AG 6202 69

5 Base + 5% w/w Akypo LF4 and + 4.5% w/w Berol AG 6202 72

6 Base + 5% w/w Akypo LF4 and + 3% w/w Ethylan CPG 660 32

7 Base + 5% w/w Akypo LF4 and + 3% w/w Plurafac LF 404 30

Akpo LF4 is a Trademark for an ether carboxylate having a formula according to that given above as defining ether carboxylates suitable for use according to the invention.

Berol AG6202 is a Trademark for an alkyl polyglycoside having a formula according to that given above as defining alkyl polyglycosides suitable for use according to the invention.

Ethylan CPG 660 is a Trademark for a modified alcohol ethoxylate used in the art as a nonionic rinse aid additive.

Plurafac LF 404 is a Trademark for an alcohol ethoxylate also used in the art as a nonionic rinse aid additive.

In a test the formulation of Example 5 above was used to wash used beer glasses in a public house using a dosage of 0.4% v/v in place of the usual two-pack commercial separate detergent and rinse aid products . The rinse performance was found to be excellent and the head and appearance of the beers served in the washed glasses, particularly that of the lagers, which are particularly sensitive to

loss of head due to detergent or rinse aid residues, were vastly improved.

Examples 8 to 10.

A further cleaning composition according to the invention comprised

62.5% water

8.0. NaOH (47% w/w)

23.0% Trisodium nitrilotriacetate (38% w/w)

2.5% Nitrilo tris-methylenephosphonic acid (49% w/w)

4.0% Ether carboxylate (Akypo LF4)

When tested for head retention by the method described in the preceding Example the cleaning composition Example 8) gave a retention time of 74 seconds in comparison with the control (Example 9) which gave 81 seconds and the base detergent, that is the composition without the inclusion of the ether carboxylate but adjusted as above described, (Example 10) which gave 77 seconds.