EP0102124A2

EP0102124A2 - Liquid detergent composition

Info

Publication number: EP0102124A2
Application number: EP83201216A
Authority: EP
Inventors: Willem Michael Maria Möhlmann; John Raymond Samuel
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1982-08-27
Filing date: 1983-08-23
Publication date: 1984-03-07
Also published as: NZ205345A; ZA836228B; JPS5958098A; AU1831383A; EP0102124A3; AU555326B2; CA1211675A; BR8304630A; NO833069L

Abstract

Aqueous, built liquid detergent compositions comprising an alkylaryl sulphonate and an alkylether sulphate as the detergent materials, and a phosphate builder show an irreversible increase in viscosity when subjected to high shearing action. The inclusion in such compositions of a certain level of a nonionic detergent surfactant according to the present invention enables the use of high shearing action, necessary to achieve the required physical stability, without an irreversible increase of the viscosity.

Description

The present invention relates to an aqueous, built liquid detergent composition which is pourable, physically stable and has a satisfactory, reversible viscosity behaviour.
Aqueous, built liquid detergent compositions are well-known in the art. A vast amount of different formulations has been described in the prior art, but basically such formulations always contain one or more detergent active compounds and one or more builder salts in an aqueous medium, and they are either true solutions, or suspensions, emulsions and the like, depending upon the type and amount of ingredients used.
The present invention is concerned with aqueous, built liquid detergent compositions of the suspension type, by which is to be understood that one or more of the ingredients of the detergent composition are suspended in the final composition.
Such types of aqueous, built liquid detergent compositi- ions have been described in the prior art. Thus, our British patent specification 855 893 describes aqueous built liquid detergent compositions in the form of pourable suspensions, emulsions or coacervates which comprise as essential ingredients an alkylethersulphate, an alkylarylsulphonate, a carboxymethyl cellulose and an alkalimetal condensed phosphate. A similar type of products is described in British patent application 2 028 365, which contain an alkylethersulphate, preferably together with an alkylarylsulphonate, a builder salt such as an alkalimetal condensed phosphate, and an optical brightening agent.
Aqueous, built liquid detergent compositions of the above type, which contain a mixture of an alkylethersulphate and an alkylarylsulphonate as the active detergent material, and an alkalimetal condensed phosphate as the builder material, suffer however from the drawback that when they are subjected to high shearing action, e.g. during their manufacture when they are e.g. pumped or bottled, their viscosity is irreversibly increased to a very significant degree, resulting in products with an unacceptably high viscosity. Some shearing action is however required to achieve the required physical stability of the products, since too low a shearing action may result in physically unstable products.
Consequently, if the manufacturer requires a product with an acceptable pourability and viscosity, he is compelled to use a medium or low shear action during manufacture, accepting a possible unsatisfactory physical stability. The control of this shear action while pumping or bottling the liquid product is, moreover, difficult. Thus, in the above British patent specification 885 893 the products are prepared by homogenisation in a colloid mill, whereby they are subjected to high shear action, resulting in physically stable, but too viscous products, and products prepared according to British patent application 2 028 365, using controlled agitation (medium and strong, avoiding aeration), result in products with an acceptable physical stability, but unsatisfactory viscosity. Storage of the latter products at temperature cycling storage conditions often results in an increased, irreversible viscosity.
It has now been found that these drawbacks can be overcome to a significant degree, if in the formulation also a certain amount of a nonionic detergent active material is included. The presence of this material enables the use of high shearing action, after which however the viscosity reyersibly returns to an acceptable level, while maintaining the physical stability achieved by the high shear action.
In its broadest aspects therefore the present invention relates to an improvement in and to aqueous, built liquid detergent compositions which contain as essential ingredients an alkylethersulphate and an alkylarylsulphonate as the active detergent materials, and a builder salt, the improvement comprising the inclusion in the composition of a certain level of a nonionic detergent active material.
Further aspects of the invention will become readily apparent from the description of the invention and its various embodiments as detailed below.
The active detergent material comprises as essential ingredients an alkylethersulphate and an alkylarylsulphonate.
The alkylethersulphates are represented by the following formula
in which R is a linear or branched alkyl chain having from 8 to 18 carbon atoms, n is 2 or 3, m is a number ranging from 1 to 10 and M is an alkalimetal, alkaline earth metal, ammonium or substituted ammonium radical.
R is preferably a linear C₁₂-C₁₅ alkyl chain, n is preferably 2, m is preferably from 2 to 5 and M is preferably sodium.
Typical examples of such alkylethersulphates are lauryl- ethersulphates containing from 2.5 to 3 moles of ethylene oxide or propylene oxide or a mixture of the two; C₁₁-C₁₅ sec. alkylethersulphates containing from 3 to 12 moles of ethylene oxide and C₁₂-C₁₅ prim. alkylethersulphates containing 3 moles of ethylene oxide, all in the form of their sodium or potassium salts.
These alkylethersulphates are normally prepared by sulphation of the corresponding alkoxylated alcohols; since the latter may contain a small amount of non-alkoxylated alcohol which on sulphation is converted into an alkylsulphate, it is to be understood that the term alkylethersulphate includes the product obtained by sulphation of the corresponding alkoxylated alcohols.
The amount of alkylethersulphate, calculated as the sodium salt, required in the composition ranges from 0.2 to 7.5%, preferably from 0.5 to 5%, and particularly preferably from 0.5 to 3.5% by weight of the final composition.
The alkylarylsulphonates are represented by the following formula
in which R is a C₁₀-C₁₈ branched or straight chain alkyl chain and M is as hereinbefore defined for the alkylethersulphates.
Typical examples of the alkylarylsulphonates are n-dodecylbenzene sulphonate, tetrapropylenebenzene sulphonate, n-pentadecylbenzene sulphonate, and linear C_l2-C_l5 alkylbenzene sulphonate in which the C₁₂-C₁₅ alkylgroup is obtained from cracked wax polymers, all in the form of their sodium or potassium salts.
Both the alkylethersulphates and the alkylarylsulphonates are well-known anionic synthetic detergents, amply described in the prior art, e.g. in the textbook of Schwartz-Perry "Surface-active Agents and Detergents", Volumes I and II of 1949 and 1958.
The alkylarylsulphonate is used in the present invention in an amount of 5-15, preferably 6-12% by weight of the final composition, the alkylarylsulphonate being calculated as the sodium salt.
The builder which is used in the composition can be any conventional organic or inorganic builder. Typical examples thereof are the alkalimetal-ortho-, -pyro- and -tripolyphosphates, -glassy polymeric phosphates, -citrates, -nitrilotriacetates, -carboxymethyloxysuccinates; zeolites, alkalimetal salts of aminopolyphosphonic acids and so on. Mixtures of various builders are also suitable.
The preferred builders are the alkalimetal phosphates such as sodium or potassium ortho-, -pyro- and -tripolyphosphate, sodiumtripolyphosphate being especially preferred. The amount of the builder present in the composition ranges from 5 to 30% by weight of the final composition, preferably from 10-25% by weight.
The nonionic detergent which is included in the composition can be any well-known nonionic detergent. Nonionic detergents usually consist of a hydrophobic moiety which has been reacted with an alkyleneoxide.
Typical examples are primary or secondary, straight- or branched-chain C_a-C₁₈ alcohols, condensed with 1-30 moles of alkyleneoxide; mono- or dialkylphenols with an alkyl group of 9-18 carbon atoms, condensed with 1-30 moles of alkyleneoxide; C₁₀-C₁₈ fatty acids or C₁₀-C₁₈ fatty acid mono- or -dialkylolamides condensed with 1-30 moles of alkyleneoxide; block copolymers of different or identical alkyleneoxides and so on. Usually the alkyleneoxide is ethyleneoxide, but propyleneoxide or mixtures of ethyleneoxide and propyleneoxide can also be used. Further suitable examples can be found in the textbook of M. Schick "Nonionic Surfactants".
The amount of nonionic to be included in the composition ranges from 0.2-5, preferably from 0.5-3% by weight of the final composition.
The weight ratio of the total amount of anionic detergent to the amount of nonionic varies from 2.5 to 1 to 25 to 1, preferably from 4:1 to 20:1.
The composition of the invention may advantageously further include a buffering agent in an amount of up to 10% by weight of the final composition. Suitable buffering agents are the alkanolamines, such as triethanolamine, buffer salts such as the alkalimetal carbonates, alkalimetal borates, alkalimetal silicates and so on. It is one of the further advantages of the present invention that the liquid compositions can tolerate appreciable electrolyte levels and that consequently further useful ingredients can be included without impairing the viscosity or stability of the formulations.
Thus, for example, alkalimetal sulphites can be included which improve the detergency; also enzymes, either alone or in admixture with enzyme stabilisers such as polyalcohols or alkanolamines with borax, can be included. Other ingredients, commonly used in liquid detergent compositions, can also be included, such as soil-suspending agents, anti-redeposition agents, hydrotropes, corrosion inhibitors, foam boosters or foam depressors, opacifying agents, perfumes, colouring agents, bleaching agents,-bleach precursors, fluorescers and the like.
In this respect it is another advantage of the present invention that any type of fluorescer can be included, also those which according to the above British patent application 2 028 365 would not be suitable for inclusion in formulations according to that prior proposal.
The products of the present invention can be prepared using conventional techniques. It has in this respect been found that it is advantageous to shear the product at the end of its production process to its maximum stable viscosity, e.g. by post-stirring or passing the product through a desintegrator or similar high shear exerting equipment. Further shear exerted on the thus treated product during its pumping or bottling does not affect the viscosity of the product further.
The invention will now further be illustrated by way of Example.
This product was prepared in the following way:

To a slurry, containing water equivalent to 52% by weight of the above formulation, 0.008% dye, 0.1% sodiumdodecyl benzenesulphonate, 0.2% fluorescer, 2.5% sodium carbonate and 15% sodium tripolyphosphate (partly in solution and partly present as hexahydrate crystals), 3.5 NaOH (34% aqueous solution) was added, followed by the addition of 10.0% dodecylbenzene sulphonic acid, subsequently 11.85% water, thereafter 2.5% of the laurylalcohol, condensed with 8 moles of ethyleneoxide and finally the sodium laurylether sulphate. The last three ingredients were added as quickly as possible after each other under slow mixing conditions.

Immediately thereafter the product was deaerated, during which step the 0.25%'perfume was added. Finally the whole product was agitated for 15-20 minutes while preventing aeration. The pH was adjusted to 10.5 + 0.25 by NaOH addition.
The product had a viscosity of 340 mPa.s (measured with a Haake Rotoviscometer at 25°C and 80 sec^-1) and a specific gravity of 1.15.
This product was stable for more than 3 months on storage at 0°C, 22°C and 37°C, respectively, and for more than 1 month at 52°C.

Example 2

In the same way as in Example 1 formulations were prepared from the same ingredients, but with varying amounts of the alkylarylsulphonate (LAS), the alkylethersulphate (LES) and the nonionic (NI) detergent. The viscosity of each of these formulations was assessed as in Example 1. The following results were obtained:

Example 3

For comparison purposes, a formulation according to Example 1 of British patent application 2 028 365 was prepared and then subjected to varying shear rates.
The formulation of Example 1 of the present application was also subjected to these varying shear rates, and of both formulations the viscosities were assessed. The following results were obtained:

With the prior art formulation the viscosity decreased with an increasing shear rate (from about 3.0 Pa.s at a shear rate of 1 sec^-1 to about 300 mPa.s at 80 sec-¹); if the viscosity of the same sample was then measured back when reducing the shear from high to low shear rates the viscosity was found to be much higher (from more than 10.0 Pa.s at 1 sec^-1 to about 800 mPa.s at 80 sec^-1).

Thus, after the product had been subjected to an increasing shear action, the viscosity increased to a much higher level when thereafter again a decreasing shear action was applied.
With the product of Example 1 of the present invention there was no difference in viscosity at increased and decreased shear rates; at 80 sec^-1 it was about 320 mPa.s in both cases and at 1 sec^-1 about 12.0 Pa.s in both instances.

Example 4

In the same way as in Example 1, using the same ingredients, a product was prepared but with 7% of sodium dodecylbenzene sulphonate, 5.5% sodium laurylethersul- phate, 0.5% nonionic detergent, 20% sodium tripolyphosphate, 3.5% sodium carbonate and 0.15% of a fluorescer, known under the registered trade name of Blankophor RKH 766.
The viscosity of this product was 430 mPa.s (measured as in Example 1) and it was stable for more than 3 months on storage at 22°C and 37°C.
The viscosity was measured at room temperature at a shear rate of 21 sec^-1, with the following results:

Example 6

The following product
had a viscosity (at 23°C and 80 sec^-1) of 300 mPa.s. The specific gravity was 1.15, the pH was 8.1.

Claims

1. An aqueous, built liquid detergent composition comprising as essential ingredients an alkylether sulphate and an alkylaryl sulphonate as detergent active materials, and a builder material, characterized in that it further contains from 0.2 to 5% by weight of a nonionic detergent surfactant.

2. A composition according to claim 1, characterized in that it contains from 0.5 to 3% by weight of the nonionic surfactant.

3. A composition according to claim 1, characterized in that it contains from 0.2 to 7.5% by weight of the alkylether sulphate, from 5 to 15% by weight of the alkylaryl sulphonate, the weight ratio of the sum of the alkylether sulphate and the alkylaryl sulphonate to the nonionic detergent surfactant being from 2.5:1 to 25:1.

4. A composition according to claim 3, characterized in that the weight ratio is from 4:1 to 20:1.