NO834150L - FOAMING, LIQUID DETERGENT MIXTURE - Google Patents

Abstract

A high-foaming aqueous liquid detergent composition suitable inter alia for manual dishwashing contains an active detergent system including (a) a dialkyl sulphosuccinate and (b) an alkyl ether sulphate (C10-C18, 1-12 EO) containing 20% by weight or less of C14 and higher chain length material. Use of this specific type of ether sulphate enables relatively low ratios of (a) to (b), for example 2:1, to be used, thus reducing hydrotrope requirements, without sacrificing foaming performance.

Description

The invention relates to high-foaming liquid detergent mixtures suitable for use in washing clothes, in shampoos and above all in manual dishwashing operations in both hard and soft water.

When we talk about "dishwashing" here, we mean the washing of utensils that are involved in the preparation or consumption of food, which it may be necessary to wash free of food particles and other food residues, fats, proteins, starches, gums, dyes,

oils and burnt organic residues.

British Patent No. 1,429,637 describes dishwashing detergent mixtures for manual use which contain as detergent active material a water-soluble salt of a di-(C 1 -C 8 ) alkyl ester of sulforavic acid, in combination with an alkyl sulfate or an alkyl ether sulfate. Various C^-C-^-alkyl ether sulfates with different chain length distributions and degrees of ethoxylation have been used, namely: (i) Sulfated C^2~ci4~linear primary alcohols with degrees of ethoxylation of 1-12, exemplified by "Empimin" ® 3023 and " Empimin"<®>3003 from Albright&Wilson, which are sulfated "narrow-cut" coconut alcohols with average degrees of ethoxylation of 10 and 3, respectively, and by "Alfol" ® 1214-7EO from Conoco, which are sulfated 55% C^2/ 45% C-^-straight-chain alcohols with an average degree of ethoxylation of 7. (ii) Sulfated C-^-C-^-primary alcohols (about 75% linear, 25% 2-methyl-branched) with average degrees of ethoxylation of 1- 12, exemplified by "Dobanol" ® 25-3 from Shell, which has an average degree of ethoxylation of 3. (iii) Sulfated randomized C^-C^ secondary alcohols with average degrees of ethoxylation of 7-30, exemplified by "Tergitol" ® 15 -S-7 and 15-S-12 from Union Carbide which are believed to have average degrees of ethoxylation of show 7 and 12.

British Patents Nos. 2,108,520, 2,104,913, 2,105,325, European Patents Nos. 71413 and 71414 describe high-foaming combinations of certain dialkyl sulfosuccinates, especially those having Cg and Cg chains, with C-^Q-C^g -alkyl ether sulfates which have

degrees of ethoxylation of 1-12, and especially with "Dobanol"® 25-3A

from Shell which, as stated above, is a sulfated ci2-<"15-

primary alcohol (about 75% linear and 25% 2-methyl-branched)

(ammonium salt) which has an average ethoxylation degree of 3.

The present invention is based on the observation that

in liquid detergent mixtures based on dialkyl sulfosuccinates and alkyl ether sulfates, both composition and performance can be improved by using a specially selected group of alkyl ether sulfates. These advantages are particularly prominent at relatively low ratios between sulfosuccinate and ether sulfate.

Accordingly, the present invention provides a foaming, liquid detergent composition in the form of a clear, aqueous solution containing at least 2% by weight of a detergent active composition comprising: (a) a water-soluble salt of a dialkyl ester of sulfoacetic acid

wherein the alkyl groups may be the same or different, and

(b) a C^Q-C-^g primary alkyl polyethoxysulfate containing 20% by weight or less of material of chain length C-^

and more and having an average degree of ethoxylation of 1-12,

the weight ratio between (a) and (b) being in the range from 5:1 to 0.5:1, preferably 4:1 to 1:1 and especially 3:1 to 1:1.

Although in principle the concentration of the detergent active mixture in the product can be as high as desired, provided that an aqueous solution can be obtained, it is preferably in the range of 2-60% by weight and more preferably in the range of 5-40% by weight.

The product according to the invention can, if desired, contain other detergent-active materials in its detergent-active mixture, provided that the product is essentially free of alkyl polyethoxy sulfates (ether sulfates) other than those defined under (b) above.

However, it is preferred that at least 2% by weight, calculated on the entire mixture, preferably at least 5% and most preferably 10%, is made up of dialkyl sulfosuccinate(s). Preferred additional ingredients are discussed in more detail below.

The dialkylsulfosuccinate component (a) can be made up if desired

of a mixture of materials with different chain lengths, of which the individual dialkyl sulfosuccinates themselves can be either symmetrical (both alkyl groups are the same) or unsymmetrical (with two different alkyl groups).

The detergent-active dialkyl sulfosuccinates are compounds of formula I:

wherein each of and R 2 , which may be the same or different, represents a straight-chain or branched alkyl group having 3-12 carbon atoms, preferably 4-10 carbon atoms and preferably 6-8 carbon atoms, and X-^ represents a solubilizing cation, i.e. any cation which gives a salt of formula I which is sufficiently soluble to be detergent active. The solubilizing cation X^

will generally be single-valued, e.g. alkali metal, especially sodium; ammonium; or substituted ammonium, e.g. ethanolamine. However, certain divalent cations, especially magnesium, are also suitable.

The alkyl groups R1 and R2 are preferably straight chain or (in mixtures) predominantly straight chain.

Among the dialkyl sulfosuccinates which can be advantageously used in the product according to the invention are the Cg/Cg unsymmetrical materials which are described and protected by British patent no. 2,105,325; the dioctyl sulfosuccinate/dihexyl sulfosuccinate mixtures described and protected by British Patent No. 2,104,913; and the mixtures of symmetrical and unsymmetrical dialkyl sulfosuccinates described and protected by British Patent No. 2,108,520.

If desired, the product according to the invention can additionally include one or more of the sulfonate-type detergents that are conventionally used as the main detergent active agent in liquid mixtures, e.g. alkylbenzenesulfonates (especially Cg-C^-linear alkylbenzenesulfonates), secondary alkanesulfonates, α-olefin sulfonates, alkyl glyceryl ethersulfonates, as well as fatty acid ester sulfonates. Naturally, dialkyl sulfosuccinates are themselves sulfonate-type detergents. If such additional sulfonate-type materials are present, the total sulfonate preferably predominates in the detergent-active mixture in the product according to the invention. If no such additional sulfonate-type materials are present, preferably the sulfosuccinate alone predominates.

If desired, one or more primary or secondary alkyl sulfates may also be present. If they are present, these dominate together with any sulfonate material as mentioned above, including the dialkyl sulfosuccinate, preferably in the detergent active mixture in the product according to the invention.

The alkyl polyethoxy sulfates or alkyl ether sulfates that make up component (b) in the product according to the invention are compounds of the general formula II:

where R3 is an alkyl group having 10-18 carbon atoms, X2 is a solubilizing cation, and n, the average degree of ethoxylation, is 1-12, preferably 1-8. In any given alkyl ether sulfate, a range of variously ethoxylated materials, as well as some unethoxylated material, will be present, and the value of n represents an average. The unethoxylated material is naturally alkyl sulfate. If desired, further alkyl sulphate can be mixed with the alkyl ether sulphate, so that a mixture is produced in which the ethoxylation distribution is more weighted towards lower values.

The special ether sulfates used in accordance with the present invention originate from primary aliphatic alcohols and are distinguished by a content of 20% by weight or less of material having a chain length of and more. The content of such long-chain material is preferably less than 10% by weight, and it is particularly advantageous to use an ether sulphate which is practically free of such material.

It is also preferred that the content of material with chain length and shorter is as low as possible. Therefore, the ether sulfate used according to the present invention preferably consists predominantly of <C>^2~ °9C^g materials.

Table 1 shows typical chain length distributions for some commercially available alkyl ether sulfates. Degrees of ethoxylation are omitted from the table, as most manufacturers supply materials with a range of different ethoxylation.

Preferred materials for use in connection with the invention are the "Dobanol" ® 23 series from Shell, which is practically free of material of chain length C-^ and above.

Such materials as "Dobanol" ® 25 from Shell and "Alfol" ® 12-14 from Conoco are clearly outside the scope of the present invention.

The ether sulfates used according to the present invention which contain 20% or less of C 2 and above in chain length material are preferably based on straight-chain or predominantly straight-chain alcohols. The "Dobanol" 2 3 series from Shell, which is highly preferred for use according to the invention, consists of 75% straight chain material and 25% 2-methyl branched material.

Difficulties have arisen with regard to preparing clear, stable liquid detergent compositions based on dialkyl sulfosuccinates and alkyl ether sulfates. At relatively high ratios between sulfosuccinate and ether sulfate (3:1 and more), relatively large amounts of hydrotrope are required in order to obtain homogeneous solutions that have acceptable low-temperature stability, which is manifested by a low cloud point, and in some cases acceptable solutions cannot be obtained compositions even when large amounts of hydrotrope are used. Hydrotropes are materials that are present in a composition to regulate solubility, viscosity, clarity and stability, but which in themselves do not actively contribute to the product's performance. Examples of hydrotropes include lower aliphatic alcohols, especially ethanol; urea; lower alkylbenzene sulphonates, e.g. sodium toluene and xylene sulfonates; and combinations of these. The lower alcohols function mainly as viscosity-reducing agents, and urea and lower alkylbenzene sulphonates mainly as solubilizing agents. Hydrotropes are expensive and take up space in a composition without contributing to its performance, and it is therefore desirable to use as little of them as possible.

The clarity and stability of mixtures based on dialkyl sulfosuccinates and conventional ether sulfates such as "Dobanol" 25 can be improved by lowering the ratio of sulfosuccinate to ether sulfate, but this also causes a drop in foaming performance.

With the specific ether sulfates used according to the invention, however, the ratio can be lowered much further without the performance being impaired, so that mixtures having both acceptable physical characteristics and excellent foaming performances can be obtained.

For example, mixtures of sulfosuccinate/"Dobanol" 25 and sulfosuccinate/"Dobanol" 23 have very similar foaming performances at ratios of 4:1, but at 2:1 the performance of the former mixture is significantly degraded while that of the latter mixture is practically unchanged .

The ether sulfate used in the product according to the invention has an ethoxylation degree n of 1-12, preferably 1-8.

Materials having n values of 2, 3 and 6.5 have all been shown to give excellent results in products according to the invention. The range 1-8 apparently gives optimal washing properties in connection with the dominant chain lengths of C, 2 °9 ci3*

As mentioned earlier, additional detergent active materials may be present in the product, provided that ether sulfates other than those specified under (b) above are absent. Thus, the ether sulfates can be supplemented or partially replaced by other sulfate-type detergents, especially primary and secondary alkyl sulfates, and/or by ethoxylated non-ionic detergents that have 8-15 carbon atoms and average degrees of ethoxylation of 5-14.

Preferred nonionic detergents are short-chain high-foaming ethoxylated alcohols of the general formula III:

where is an alkyl group, preferably straight chain, having 8-12 carbon atoms, and the average degree of ethoxylation m is 5-12.

The weight ratio between alkyl ether sulfate and nonionic detergent is preferably at least 1:1 and more preferably in the range from 1.5:1 to 3:1, especially approx. 2:1. A particularly preferred nonionic detergent is "Dobanol"<®>91-8 from Shell, where R4 is Cg-C11 (predominantly straight chain) and m is 8.

The stable liquid detergent mixtures according to the invention, preferably containing 2-60% by weight of detergent-active material, can be used for all normal washing purposes where foaming is advantageous, e.g. for laundry products, for cleaning preparations for general household and industrial use, carpet shampoo, car wash products, washing products for personal hygiene, shampoo, foam bath products, and, above all, for manual dishwashing.

As well as washing-active material, water and (if necessary) hydrotrope, the products may contain the usual small ingredients such as e.g. perfume, colouring, preservatives and germicides.

In the following, the invention shall be illustrated by means of

the non-limiting examples.

In the examples, the foaming performance of different mixtures was compared in a plate washing test. In the test, plates were soiled with a standard mixture of starch, fat and fatty acid and washed in the standard way with 5 liters of test solution (total concentration of the product 1.0 g/litre or 1.5 g/litre in water of 5°H

or 24°H (French hardness) at 45°C) in a barrel, until only one third of the surface of the solution in the barrel was covered with foam.

The number of plates that were washed before this arbitrarily set end point was reached was counted as an indicator of washing and foaming performance.

Examples 1-3

The performances of mixtures of dialkyl sulfosuccinate and two different ether sulfates (one according to the invention, the other not) in different ratios were compared at a dosage of 1.0 g/liter in hard water (24°H).

The dialkylsulfosuccinate used was a statistical mixture (molar ratio 1:2:1) of di-n-octylsulfosuccinate, n-hexyl-n-octylsulfosuccinate and di-n-hexylsulfosuccinate (sodium salts), prepared from a 1:1 mixture of n -hexanol and n-octanol by the method described in example 1 in British Patent No. 2,108,520.

The ether sulfate according to the invention was "Dobanol" 23-3A from Shell (50%C^2,50%C-^r n = 3; ammonium salt) while the comparison material was "Dobanol" 25-3A from Shell (25% each of ^12'C13' C14°^^15'n = 3; ammonium salt).

The concentration of total detergent active material in each mixture tested was 25%.

The results obtained were as follows:

Comparison between mixtures A and B (outside the invention) shows that a reduction in the ratio (a):(b) from 4:1 to 2:1 gives a significant reduction in performance. When the mixtures 1, 2 and 3 according to the invention are compared, it will be seen that at 2:1 the performance is not significantly worse than at 4:1, and even at 1:1 it has not fallen as low as that of mixture B.

Example 4

Example 2 was repeated with "Dobanol" 23-2A (which had

n = 2, but was otherwise identical to "Dobanol" 23-3A) in both hard and soft water. The results were as follows:

No significant difference in performance was observed.

Examples 5&6

The hard water performance of the system dialkyl sulfosuccinate/- "Dobanol" 23-3A at a ratio (a):(b) of 2:1 was compared with the values of similar systems containing three other alkyl ether sulfates, the tests being performed at product dosages of both 1.0 and 1.5 g/litre. The ether sulfates used were "Dobanol" 23-3A and "Dobanol" 25-3A as in example 1; "Empimine"

3003 from Albright&Wilson, as used in British Patent No. 1,429,637 referred to earlier, and "Dobanol" 23-6.5A from Shell, which has an average degree of ethoxylation of 6.5, but

which is otherwise similar to "Dobanol" 23-3A. The chain length distributions for all these materials are given in Table 1 above. Each test mixture contained 16% by weight of the dialkyl sulfosuccinate mixture used in previous examples and 8% by weight of the ether sulfate.

The results were as follows:

The results obtained at a product dosage of 1.0 g/litre show a similar effect to that observed in examples 1 to 3, where the mixtures 5 and 6 according to the invention were clearly superior to the comparison mixtures C and D.

The higher ethoxylated material "Dobanol" 23-6.5A gave even better results than "Dobanol" 23-3A.

Examples 7-9

Fully mixed products containing the sulfosuccinate mixture according to previous examples and various ether sulfates were prepared and their physical characteristics measured. Comparative mixtures A1 and A2 correspond in terms of ingredients and levels of detergent-active material to comparative mixture A in examples 1-3, and mixture 5 here corresponds to mixture 5 in example 5. "Dobanol" 23-2S is the sodium salt corresponding to "Dobanol" 23-2A used in example 4.

Comparative example A1 shows a 4:1 dialkyl sulfosuccinate/ether sulfate mixture outside the invention; the relatively high level

(20%) of hydrotrope will be noted. Comparative example A2 shows that when an attempt was made to reduce said level to 12%, an unstable product was obtained. Stability was regained only by reducing the ratio of sulfosuccinate to ether sulfate to 2:1, as in compositions 5, 7 and 8 according to the invention. These blends also showed advantageous features with higher viscosity.

Blend 9 which is according to the invention, and which has a higher washing active level, required some ethanol as well as urea to achieve a low cloud point, and the viscosity was lower, but not unacceptable.

Examples 10&11

The effect on performance of including a non-ionic detergent in compositions according to the invention was investigated in both hard and soft water, at a dosage of 1.0 g/litre.

As non-ionic detergent, "Dobanol" 91-8 from

Shell, which, as mentioned earlier, Cg_cii is mainly straight-chain primary alcohol with an average degree of ethoxylation of 8. The ratio of sulfosuccinate to the other detergents was 2:1 in each case, and the concentration of total detergent active material was 27%.

The results were as follows:

No significant difference in performance was observed.

Example 12

A mixture according to the invention containing a further ingredient - primarily alkyl sulphate - was prepared. The latter material was "Dobanol" 23-A from Shell which is the non-ethoxylated analogue of "Dobanol" 23-3A. The mixture contained 12% by weight of the dialkyl sulphosuccinate mixture used in the preceding examples, 8% by weight "Dobanol" 23-A, and 8% by weight "Dobanol" 23-3A. It required only 4 wt% urea to have a cloud point of -4°C, and its viscosity - 430 cP - was high. The foaming performance in hard water, as shown in the plate washing test at a dosage of 1.0 g/liter, was comparable to that of similar compositions containing no alkyl sulfate.

Claims (10)

1. Foaming, liquid detergent mixture in the form of a stable, aqueous solution containing at least 2% by weight of an active detergent mixture comprising a) a water-soluble salt of a dialkyl ester of sulforauric acid in which the alkyl groups may be the same or different, and b) an alkyl polyethoxy sulfate, the weight ratio between (a) and (b) being in the range from 5:1 to 0.5:1, characterized in that the alkylpolyethoxysulfate (b) is a C^g-C^g primary alkylpolyethoxysulfate containing 20% by weight or less of material with chain length C,^ and above, and with an average degree of ethoxylation of 1-12. 2. Detergent mixture as stated in claim 1, characterized in that the alkylpolyethoxysulfate (b) contains less than 10% of material with chain length C, . and above. 3. Detergent mixture as stated in claim 2, characterized in that the alkylpolyethoxysulfate (b) is essentially free of material with a chain length and above. 4. Detergent mixture as stated in any one of claims 1 to 3, characterized in that the alkylpolyethoxysulphate (b) has an average degree of ethoxylation of from 1 to 8. 5. Detergent mixture as stated in any one of claims 1 to 4, characterized in that the alkyl polyethoxysulfate (b) is derived from straight-chain or predominantly straight-chain aliphatic alcohols. 6. Detergent mixture as stated in any one of claims 1 to 5, characterized in that it contains 2-60% by weight of the active detergent mixture. 7. Detergent mixture as stated in any one of claims 1 to 6, characterized in that the ratio between (a) and (b) is in the range from 4:1 to 1:1. 8. Detergent mixture as set forth in any one of claims 1 to 7, characterized in that dialkyl the sulfosuccinate (a) constitutes at least 5% by weight of the entire mixture. 9. Detergent mixture as stated in any one of claims 1 to 8, characterized in that the alkyl groups in the dialkyl sulfosuccinate (a) each have from 4 to 10 carbon atoms. 10. Detergent mixture as set forth in any one of claims 1 to 9, characterized in that the active detergent mixture further comprises an ethoxylated non-ionic detergent having an alkyl chain length of cg ~ cjLc)°9 an average degree of ethoxylation of 5-14, the ratio between the alkylpolyethoxysulfate (b) and the nonionic detergent is at least 1:1.