The present invention relates to a detergent formulation intended particularly but not exclusively as a so-called "washing up" liquid for use in washing crockery, cutlery, pans and other domestic utensils which have been used in the preparation and/or consumption of food and which have deposits of dirt, food, grease, burnt residues etc. The detergent formulation is also intended, not exclusively, as a "hard surface" cleaner.
Purchasers of "washing up" cleaning liquids generally regard two particular properties as being of importance. One is that a relatively small quantity of the liquid will suffice for washing a particular number of utensils. In other words, the purchasers like to feel that the liquid is economical to use. The other property is that the liquid generates a relatively large volume of suds (i.e. the liquid has good lathering characteristics) since it is generally assumed that such suds contribute to the efficiency of the liquid.
According to the present invention there is provided a liquid detergent formulation comprising, by weight, 5-10% of an alkyl (C8-22) sulphate, 5-10% of an alkyl (C8-22) ether sulphate, 0-3% of an amine oxide containing at least one C8-22 alkyl group, 1-6% of an amphoteric betaine surfactant containing at least one C8-22 alkyl group, 2-10% of an ethoxylated alcohol (C8-22), 2.5-9% of an alkyl (C8-22) polyglycoside and a balance of water.
It has been found that a liquid detergent in accordance with the present invention has excellent cleaning properties. In particular the liquid detergent provides an outstanding foam height, which persists for a long time both on standing and in washing greasy plates, both properties being desirable to the user. More importantly the liquid detergent is not only effective at removing greasy deposits from hard surfaces but also for retaining said grease particles in solution stopping them from being re-deposited.
This result shows a surprising improvement over the disclosure contained within
The composition of the invention includes at least one C8-22 alkyl sulphate used in an amount of 5-10% by weight of the formulation, more preferably 8-10% and most preferably 9-10%.
The invention is particularly beneficial with the use of an amount of alkyl (C8-22) sulphate lower than that disclosed in
The alkyl sulphate is preferably an alkali metal alkyl sulphate with the preferred alkali metal being sodium.
For preference, the alkyl group of the alkyl sulphate has 8-16 carbon atoms. The alkyl sulphate may be a single compound (preferably C12) or may comprise a mixture of alkyl sulphates of different chain lengths, preferably with C12 predominating. For preference the alkyl groups are primary alkyl groups and preferably straight chain.
The carbon chain of the alkyl sulphate may be produced synthetically or may be derived from natural products (e.g. coconut oil) so that the chain length distribution of the alkyl group will correspond to that in the natural product from which it is derived.
The alkyl sulphate may be a "narrow cut" lauryl sulphate having carbon chains principally of C12 to C14 (C12 predominating), e.g. 60-70% C12, 20-30% C14 plus minor amounts of C10 and C16.
A preferred alkyl sulphate is available under the name Empicol LX28 (Albright & Wilson).
The alkyl (C8-22) ether sulphate is preferably used in an amount of 5-10%, by weight of the formulation, more preferably 6-9% and most preferably 7-8%.
The invention is particularly beneficial with the use of an amount of alkyl (C8-22) ether sulphate lower than that disclosed in
The cation present in this material may, for example, be an alkali metal (particularly sodium) or ammonium. It is particularly preferred that the alkyl ether sulphate be an alkyl (C8-22) ethoxylated (n = 1 to 5, preferably 2 or 3) sulphate.
The alkyl group of the ether sulphate may be as described for the alkyl sulphate.
The most preferred alkyl ether sulphate for use in the invention is sodium lauryl ether sulphate where n = 2 or 3.
An alkyl ether sulphate which may be used is available under the name Empicol 0251 (Albright & Wilson).
The formulation of the invention contains 0 to 3%, more preferably 1 to 3%, of an amine oxide containing at least one C8-22 alkyl group. The amine oxide preferably has one such group of C8-22 carbon atoms and two C1-4 alkyl groups. Most preferably the latter alkyl groups are methyl groups. Preferred amine oxides are therefore (C8-22) alkyl dimethyl amine oxides. The long chain alkyl group may, for example, have 8-18 carbon atoms and the compound may comprise a mixture of alkyl groups, which are preferably C10 to C18 (with C12 predominating).
A suitable amine oxide is available under the name Genaminox CSX (Hoechst).
The betaine surfactant is used in the formulation of the invention in an amount of 1-6%, more preferably 0.5-4%. Preferred betaines may be either of the formula (I) or (II).
In the above formula, R1 and R2 may be the same or different C1-4 alkyl groups whereas R3 is an alkyl group having 8-22 carbon atoms, e.g. mixed C10 to C14.
The preferred betaine for use in the formulation of the invention is cocoamidopropyl betaine.
A suitable betaine is available under the name Rewoteric AMB14 (Witco).
A further component of the formulation of the invention is the ethoxylated alkanol (C8-22) which is used in an amount of 2-10%, more preferably 2-9% and most preferably 2-7%.
Examples of such ethoxylated alkanols which may be used are those in which the alkanol (from which the product is derived) is a primary alcohol and is preferably linear. Preferably the alkanol has 6 to 11 carbon atoms (e.g. mixed C9-C11) and in which the degree of ethoxylation is 5-15 (particularly 8-10).
A suitable fatty alcohol ethoxylate is available under the name Lutensol ON80 (BASF).
The formulations of the invention contains 2.5-9% alkyl (C8-22) polyglycoside by weight. It is known by those skilled in the art that a glycoside is a sugar derivative, wherein one or more of the hydroxyl functions, which may preferably be on the first carbon atom of the sugar molecule, is/are replaced by another group such as an alcoholic or phenolic group. It is also known that such functionalised sugar molecules may be linked to one or more other sugar molecules, either before or after functionalisation, to form a polyglycoside. The preferred glycoside employed in the present invention is a glucoside (i.e. based on glucose), functionalised with a primary alcohol (e.g. C12-C14). More preferably the glucoside is in the form of a polyglucoside, with a preferable average degree of polymerisation of between 1-2, most preferably about 1.4.
A suitable polyglycoside is available under the name Glucopan 600CSUP (Henkel).
A further optional component which may be used in the formulation of the invention is a hydrotrope which may be used in an amount up to 7%, e.g. 3%, of the formulation. A particular preferred hydrotrope is sodium xylene sulphonate.
The formulation may contain the usual minor addition such as preservatives, dyes and/or perfumes.
The invention will be illustrated with reference to the following non-limiting Examples.
Formulations A to K were prepared as shown below.
In the above table, the percentages represent amount of active material. It should be noted that only formulations C,D and K were prepared in accordance with the present invention. Formulations A,B and E to J were prepared as comparative examples.
The above formulations were compared for their effectiveness in preventing oily soil being re-deposited on clean surfaces by a plate washing test.
The plate washing test was a standard test used to determine the number of plates which could be washed using a predetermined quantity (0.2g/litre) of the detergent formulation. The plates had each been soiled with 2 ml of melted lard, which contained a red dye (Red number 17 90095 available from Ellis and Everard) for ease of visibility on the white plates and which was applied in the form of small drops and then allowed to harden for 24 hours. For each formulation test 25 such plates were prepared.
The plates were washed one at a time in a 5 litre bowl of water, which had been preheated to 50°C and which contained 0.2g/litre of detergent formulation. The washing was stopped when the foam produced by the formulation no longer covered the surface of the water. After washing the plates were assessed for cleanliness, being divided into three categories, as follows:
- 1) Not cleaned at all, i.e. not washed because the foam no longer covered the surface of the water in the bowl.
- 2) Superficially clean but observed to be slightly soiled upon close examination.
- 3) Totally clean.
The above formulations were tested using the plate washing test as described above.
Formulations C,D and K not only were observed to clean the highest number of plates but also demonstrated a relatively low number of superficially clean plates. Both properties are of utmost importance to the user.
Formulations A (lacking the fatty alcohol ethoxylate), E (lacking fatty alcohol ethoxylate and the polyglycoside) and H (lacking the fatty alcohol ethoxylate and betaine) performed considerably worse, leading to a lower number of plates cleaned and an equal or higher number of superficially clean plates. Formulation B (lacking the polyglycoside) performed worse still, leading to a very high number of dirty plates.
Similarly formulations G, I, J (not containing enough of the polyglycoside) and F (lacking the betaine) did not perform as effectively as formulations C,D and K.
In the above table, the percentages represent amount of active material. It should be noted that formulations A1-A2 and A4-A6 were prepared in accordance with the present noted that formulations A1-A2 and A4-A6 were prepared in accordance with the present invention. Formulations A3 and A7 were prepared as comparative examples.
The above formulations were tested using the plate washing test as described above.
Formulations A1 and A2 were observed to clean the highest number of plates but also demonstrated the lowest number of superficially clean plates.
Formulation A3 did not contain enough of the polyglycoside to perform as effectively as formulations A1 and A2.
The above formulations were also tested using a mixed soil plate washing test. In this test 3 grams of food residue, comprising 40% potato, 30% lard, 10% egg and 20% minced beef by weight, was applied to each plate and allowed to harden for 24 hours.
The plates were washed as in the lard soil platewash and assessed for cleanliness using the same criteria.
Formulation A7 performed worse than formulations A4 and A5, as a result of lower polyglycoside content even though the formulation A7 had an equal if not considerably greater concentration of sodium lauryl sulphate.
The lathering performance was judged by a standard test in which 200 ml of a 1% solution of the formulation is drained into a measuring cylinder from a separating funnel positioned 75 cm above the base of the cylinder. The height of the lather produced after 1 minute and after 30 minutes was measured.
The results of the foam height testing are shown in the table below.
This consideration is also very important to the user. Formulation A3 produced a significantly lower foam that formulations A1 and A2 in both parts of the test, as a result of a lower polyglycoside content.
It will be appreciated from the information presented above that formulations in accordance with the invention are of considerably improved performance as compared to the prior art.