GB2278125A

GB2278125A - Detergent composition

Info

Publication number: GB2278125A
Application number: GB9310156A
Authority: GB
Inventors: Kenneth Metcalfe; Peter James Powers; Bakir Abbood Timimi
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1993-05-17
Filing date: 1993-05-17
Publication date: 1994-11-23
Also published as: IN181479B; GB9310156D0

Abstract

A non-soap detergent bar contains 10 to 60% by weight of non-soap anionic detergent active, at least a majority of which is linear or branched C8 to C22 alkylbenzene sulphonate constituting at least 10% by weight of the bar while primary alkyl sulphate is absent or is at most one tenth the quantity of alkyl benzene sulphonate; and 5 to 90% by weight of detergency builder, water-insoluble inorganic filler or a mixture of the two. The bar additionally contains from 0.3 to 10% by weight of at least one alcohol containing 8 to 24 carbon atoms; this enhances the integrity of the bars in contact with water, reducing the formation of soft mush.

Description

DETERGENT COMPOSITION This invention relates to non-soap detergent bars which are used in some countries for the laundering of fabrics and also the cleaning of hard surfaces. Such bars customarily contain detergency builder, waterinsoluble inorganic filler or both, in addition to detergent active.

A number of properties are regarded as significant for satisfactory bars. One property concerns the behaviour of a bar when left standing in water. It is undesirable that the outer part of the bar should break up and be lost. It is also undesirable that the outer part of a bar should turn into a soft layer - referred to as mush - which can then be removed by rubbing or scraping.

On the contrary, satisfactory bars should retain their integrity when in contact with water, without however being so hard that the bar composition does not rub off onto fabrics when used.

We have now found that the incorporation of a small amount of an alcohol containing 8 to 22 carbon atoms is effective for enhancing the integrity, in contact with water, of bars containing alkyl benzene sulphonate as the sole, or predominant anionic detergent.

Thus, according to this invention, there is provided a non-soap detergent bar containing 10 to 60k by weight of non-soap anionic detergent active, at least a majority and preferably at least four fifths linear or branched C5 to C18 alkylbenzene sulphonates, the amount of said alkyl benzene sulphonate being at least 10% by weight of the bar; and 5 to 90% by weight of detergency builder, waterinsoluble inorganic filler or mixture thereof; wherein the bar additionally contains from 0.3 to 10% by weight of at least one alcohol containing 8, better 10 up to 24 carbon atoms.

The features of this invention, and also some preferred and optional features, will now be discussed in turn: Deterrent active As already mentioned, the composition includes nonsoap anionic detergent active in an amount from 10 to 60wt% of the overall composition. It is envisaged that the amount will generally range from 12 to 40 or 45wt% and a particularly envisaged range is from 15 to 40wt%.

Amounts over 45wt% up to 60wt% may, however, be used.

Preferably, the total of all detergent active is not over 65 wt%.

It is required that more than half of the anionic detergent active present in bars of the present invention is one or more: alkylbenzene sulphonates of formula R - C6H4 SO3M wherein R is a linear or branched primary alkyl or alkenyl group containing 8 to 22 carbon atoms, preferably 10 to 18 carbon atoms, more preferably 10 to 16 carbon atoms, and M is a cation such that the alkyl benzene sulphonate is water soluble. The group R will frequently be linear or branched alkyl.

The anionic detergent active which is present is likely to consist solely of alkyl benzene sulphonate.

Lesser amounts of some other anionic detergent actives may possibly be included. These may in particular be other anionic detergent actives which include a sulphonate group, (which is of course joined to a carbon chain through a carbon-sulphur bond).

Other anionic detergent actives which may be included as a minority of the anionic detergent active (preferably not more than one fifth of it by weight) are other alkane sulphonates, secondary alcohol sulphates, oleo in sulphonates, fatty acyl isethionates, fatty acid ester sulphonates and ethoxylated alcohol sulphates.

In this invention primary alkyl sulphate will generally not be present in a quantity which is greater than one tenth the quantity, by weight, of alkyl benzene sulphonate.

Other classes of detergent may be present, preferably in amount not exceeding 10% by weight of the composition.

Betaines, which are amphoteric detergents, amine oxides which are polar nonionic detergents and fatty acyl amides and alkanolamides which are also polar nonionic detergents are examples of other detergents which may be included, more preferably in amount not exceeding 5% by weight of the composition, e.g. 3% by weight.

It is possible within the scope of the invention to include soap but it would generally be absent because it inhibits the formation of lather by the non-soap detergent active. Consequently it is preferred that if soap is present at all, the amount of it does not exceed 2% by weight of the bar composition.

Alcohols The alcohols used in this invention will generally be primary or secondary alcohols, with either linear or branched chains. They must contain from 8 to 24 carbon atoms. Preferred is at least 10 or 11 carbon atoms. The number of carbon atoms will generally not exceed 20 and a range from 11 to 18 is preferred.

The amount of such alcohol must be from 0.3 to 10% by weight, Generally it will be adequate to use amounts up to. 5% or even up to 3% by weight. Preferred is to use at least 0.5t by weight better at least 1%.

It will usually be the case that the amount of anionic detergent active is at least three, and possibly at least four or five times the amount of alcohol.

Linear primary alcohols may be desirable on grounds of availability and/or cost. On the other hand, bars in accordance with this invention may contain secondary or branched alcohol without any significant content of linear primary alcohol.

Yet again a mixture of alcohols may be used which includes some linear primary alcohol together with secondary or branched alcohol.

Linear primary alcohols These have the simple schematic formula R-OH in which R is an alkyl or alkenyl group. They are widely available commercially.

Branched chain alcohols Branched chain alcohols can be depicted by a schematic formula

where n is at least one and R1 and R2 are alkyl or alkenyl groups, probably differing in length. R1 and R2 may both be linear alkyl or alkenyl, although they can also be branched.

One preferred category of branched chain alcohols is the Guerbet alcohols which have branching at the 2position and so have the schematic formula

where R1 and R2 are both linear or branched alkyl or alkenyl groups, usually both linear alkyl.

These alcohols can be made by the Guerbet reaction which is a high temperature condensation reaction between two alcohol molecules, leading to a 2-alkylalkanol. The reaction can be represented as:

If a mixture of alcohols is used the reaction can take place between different alcohol molecules, thus

as well as taking place between molecules which are the same.

The reaction is brought about by heating in the presence of a catalyst. Various materials can serve as catalyst, notably nickel and lead salts, oxides of copper, lead, zinc, chromium, molybdenum, tungsten and manganese, and also compounds of palladium and of silver.

A series of Guerbet alcohols containing from 12 to 24 carbon atoms is available from M. Michel and Co. Inc.

New York. They do not contain any substantial quantity of linear alcohol. Guerbet alcohols are also available from Condea Chemie, Hamburg.

A mixture of alcohols incorporating a high proportion of alcohols with branching at the 2-position can be made by the Oxo process. Such a mixture typically contains branched alcohols in a quantity which is more than four times the quantity of linear alcohols.

Such alcohols are available as the Lial series of alcohols, from Enichem, Augusta, Sicily. For example Lial 125 contains a mixture of alcohols with 12 to 15 carbon atoms. Linear alcohols constitute 40% of the mixture while 60% of the mixture are alcohols with branches at the 2-position.

Lial 111 is C11 alcohol of which 50% is straight chain and 50% is branched at the 2-position.

Lial 123 is a mixture of C12 and Cl3 alcohols, 58% of which are branched.

Acropol 35, available from Exxon at either Harnes, France or Rozenburg, Netherlands is a mixture of C13 alcohols and C15 alcohols. Linear C13 and C15 alcohols were found to provide 65% of a sample. The remainder is mostly C13 and C15 alcohols branched at the 2-position.

Secondarv alcohols These can be depicted by the general formula

where R1 and R2 are linear or branched alkyl or alkenyl groups, probably differing in length.

Such alcohols are supplied under the Trade Mark Softanol by Nippon Shokubai, Osaka, Japan.

Detergency builder Bars according to this invention preferably incorporate from 2 to 60% by weight of detergency builder, preferably at least 3%, better at least 5% and most preferably from 10 to 45%. The detergency builder may be a water-soluble builder, water-insoluble builder, or a mixture of the two.

Examples of water-soluble builder components are: water soluble phosphate salts, e.g. sodium and potassium, tripolyphosphate, pyrophosphate and orthophosphate; water soluble carbonates, e.g. sodium carbonate; organic builders, e.g. sodium nitrilotriacetate, sodium tartrate, sodium citrate, trisodium carboxymethyl oxysuccinate, sodium oxydisuccinate, sodium sulphonated long-chain monocarboxylic acids, polyacrylates and oxidised polysaccharides. Significant forms of this invention are bars in which the builder comprises water-soluble phosphate or polyphosphate detergency builder in an amount which is at least 2%, better at least 3%, 5% or even 10% by weight of the bar composition.

A water-insoluble detergent builder which may be included in a bar formulation is aluminosilicate ion exchanger, such as natural and synthetic zeolites. This may possibly be used in amounts up to 40% by weight of the bar, e.g. 5 to 40%.

Water-insoluble material Bars according to this invention will usually contain up to 40% by weight of water-insoluble material, notably from 2% or 5% up to 40%.

It is conventional that bars include water-insoluble material, customarily referred to as filler which helps to form the structure of the bar. Clays, notably kaolin and bentonite are conventional for this purpose. So is calcite. If a water-insoluble detergency builder is present, this will also contribute to the content of water-insoluble material. Preferably, bars of ths invention contain 5 to 40% of water-insoluble filler selected from clays and calcite.

Although it is not an essential feature, bars embodying this invention may include a structuring system consisting of a water-insoluble metal compound precipitated during manufacture of the bars. GB Patent 2,099,013 describes the use of aluminium salts and a soluble silicate to form aluminosilicate in situ.

GB 2,234,982A describes the use of further polyvalent metal compounds and siliceous compounds to provide a structuring system. GB 2,235,205A discloses the use of phosphates in the provision of water-insoluble structuring material. These prior disclosures are incorporated herein by reference.

The systems of one or other of these prior disclosures are preferably used in the bars of the present invention and contribute to the content of waterinsoluble material.

Other ingredients The bars of this invention may optionally include various other materials, both soluble and insoluble.

Water-soluble salts such as sodium and potassium sulphate may be included as a soluble filler.

The water-soluble alkali metal salts of those sulphur oxo acids which are reducing agents may be included in the composition as bleaches. Preferred is to incorporate from 1 to 15% by weight of such material, better at least 2% or even at least 7.5k by weight.

These materials can be used in conjunction with a photobleach such as aluminium phthalocyanine sulphonate.

Other detergent additives include antiredeposition agents such as sodium carboxymethyl cellulose, starches, colouring materials, fluorescers, polyvinyl pyrrolidones, protein hydrolysates and germicides, opacifiers, humectants such as glycerol, polyethylene glycols, perfumes and alternative bleaches such as sodium perborate and potassium monopersulphate. Enzymes may also be included, notably proteases, lipases, amylases and cellulases.

Detergent bars according to this invention may be formulated to yield an alkaline liquor when used. This may be done by including sodium carbonate and/or sodium silicate to raise the alkalinity, (typically to a pH in the range 9.8 to 11.4 when determined as below).

However, we have found that it is both possible and advantageous to formulate detergent bars so as to give a reduced alkaline pH when placed in water. Accordingly the composition of bars embodying this invention may be such that the composition generates a pH in the range from 7.0 to 9.8 when mixed with deionised water at a weight ratio of composition: water of 2.5:97.5 and allowed to dissolve as completely as possible at a temperature of 200C.

In practice the pH of a composition will not vary much with temperature, so that a pH value measured at any temperature in the range from 150C to 300C will be adequately accurate.

It is preferred that the pH, measured at 200C as stated above, lies in a range from 7.5 to 9.6. The pH may well lie above a lower limit of pH 8.0.

Alternatively, or in addition, it may lie in a range not exceeding pH 9.3 or even pH 9.2.

Depending on the intended pH other less alkaline salts may be introduced to provide further control of the pH. Thus for instance sodium carbonate may be at least partially replaced with bicarbonate or borax. Phosphate acid builder salts can help to buffer the pH which is developed on mixing with water. Metal salts which are acidic in solution may be included in bars of this invention, e.g. zinc salts in amounts up to 10% by weight.

In use, of course, the proportions of mixing with water are not controlled and deionised water is not used.

Nevertheless the pH which is generated in use will be adequately related to that measured under the stated conditions, since it is largely controlled by the salts in the composition.

To prepare bars according to this invention, it is preferred to use if possible the acid form of the detergent(s) active, neutralising them in a mixer and adding other ingredients such as insoluble filler(s), phosphate builder(s) and finally minor ingredients such as perfume. In the case of alkyl sulphate it is not possible to use the acidic form of the detergent, because it decomposes to the primary alcohol from which it was made. Therefore alkyl sulphates are added to the mixture in the form of their alkali metal salts.

Mixing can be carried out in a high shear mixer and be followed by conventional extrusion and bar stamping.

The required secondary or branched alcohol may be added at any stage, but preferably after neutralisation.

GB 2,099,013, 2,234,982 and 2,235,205 explain when to add materials which react in situ to form an insoluble structuring system.

Neutralisation is preferably effected by the known procedure of dry neutralisation, in which a carbonate (usually soda ash) is added to the acidic mixture.

Neutralisation in other ways, such as with very concentrated sodium hydroxide solution or a mixture of sodium hydroxide and soda ash, is also possible.

The invention will be further explained and illustrated by means of the following examples, in which all proportions and percentages are by weight unless otherwise stated.

In these examples, bars with the compositions given were manufactured on a conventional plant for the manufacture of NSD bars. This plant consisted of a sigma mixer, mill and vacuum plodder.

All mixing of ingredients took place in the mixer, as did neutralisation of the acid form of the anionic detergent, as indicated above. When the anionic detergent included primary alkyl sulphate, this was added to the mixer in pre-neutralised (i.e. sodium salt) form.

All bars were made with the same dimensions.

The bars were tested for hardness, integrity when wet, and rate of wear.

Hardness was measured using a SUR PNR10 penetrometer, fitted with a needle of 9 cone angle and a 100 g weight. An initial measurement was made on freshly extruded bars and a "finial" measurement was made after 3 days.

Integrity of bars when wet was measured by the following test for mush formation and loss. The test bar is weighed, and then suspended partially immersed in a 400 ml beaker containing 250 ml water of 200 French hardness at 260C such that a 3 cm length of the bar is immersed in the water. The bar is left in the water for six hours. During this period some of the bar material forms a sediment at the bottom of the beaker whilst some dissolves into solution. The bar is then withdrawn from the beaker and placed on a petri dish and scraped with a knife to remove soft mush clinging to its surface. The remaining bar is dried to constant weight in an oven.

The difference in its weight at the end of the experiment and its starting weight is the weight lost on mushing.

It will be appreciated that the above test is a realistic assessment of loss of weight in a typical wash procedure.

Rate of wear is measured as the loss in bar weight during a procedure in which a bar is rubbed 500 times (by machine) on a test cloth wetted with water of 200 French hardness at ambient temperature.

The pH of the bars was tested as mentioned above by mixing bar composition with deionised water in weight ratio 2.5:97.5, allowing to dissolve as completely as possible at 200C, and then measuring the pH of the solution.

Example 1 Bars were prepared using alkyl benzene sulphonate as sole anionic detergent. The bars contained up to 3% by weight of coconut alcohol, which is a mixture of linear primary alcohols mostly of 12 and 14 carbon atoms.

Formulations of the bars and their observed properties are given in the following Table 1. Control bars did not contain any alcohol.

The initials ABS denote sodium linear alkyl benzene sulphonate having approximately twelve carbon atoms in its alkyl chain.

STP is sodium tripolyphosphate.

TABLE 1 INGREDIENTS k BY WEIGHT COCONUT ALCOHOL 0 1 2 3 ABS 22 22 22 22 SODA ASH IN EXCESS 0.5 0.5 0.5 0.5 OF AMOUNT FOR NEUTRAL I SAT ION ALKALINE SILICATE 7 7 7 7 (48%) ALUMINIUM SULPHATE 8 8 8 8 STP 12.5 12.5 12.5 12.5 CALCITE 8.25 8 7.75 7.5 KAOLIN 24.75 24 23.25 22.25 SODIUM SULPHITE 7.5 7.5 7.5 7.5

MINOR INGREDIENTS < ---BALANCE TO 100a---- > AND WATER PROPERTIES TOTAL WATER:: THEORETICAL 12.5 12.5 12.5 12.5 MEASURED 6.1 8.8 9.9 9.7 pH 9.5 9.5 9.5 9.5 PENETROMETER (mm) INITIAL 4.0 5.5 6.9 5.5 FINAL 0.9 1.9 2.0 1.8 RATE OF WEAR (g) 7.5 7.0 6.6 6.5 MUSH LOSS (g) 14.0 10.8 9.8 8.5 As can be seen from Table 1 above the addition of the alcohol gave an improvement in mush formation and loss without serious detriment to the values for final hardness and rate of wear.

Example 2 Example 1 was repeated using different alcohols.

Two formulations used a Guerbet alcohol of twelve carbon atoms (Michel XO-150-12) in different amounts.

Another formulation used LIAL 125 which is a commercial mixture of C12-Cl5 alcohols mostly branched at the 2position. It can be described briefly as containing 20.8% C12, 30.4% C13, 17.7% C15 chain lengths with 60.3% branching. The various alcohols present in this mixture are set out in more detail in Table 2 below.

The formulations and results are set out in Table 3 below. Again there was an advantageous reduction in mush formation and loss.

TABLE 2 LIAL 125 20.8k C12 30.4% C13 30.8% C14 17.7% C15 with 60.3% branching LINEAR SIDE CHAIN MAIN CHAIN NONE C12 10.5 C11 2-METHYL C11 3.5 C10 2-ETHYL C10 1.8 C9 2-PROPYL C9 1.9

2 -BUTYL C8 3.1 2-PENTYL C7 NONE C13 11.2 2-METHYL C12 5.0 2-ETHYL Cl1 2.8 2-PROPYL Cl0 3.3 2-BUTYL C9 3.8 2-PENTYL C8 4.3 NONE C14 12.2 2-METHYL C13 4,4 2-ETHYL C12 2.5 2-PROPYL C11 2.8 2-BUTYL C10 3.4

2-PENTYL C9 5.5 2-HEXYL Cs NONE C15 5.8 2-METHYL C14 2.3 2-ETHYL C13 1.3 2-PROPYL C12 1.6 2-BUTYL C11 2.1 2-PENTYL C10 2.4 2-HEXYL C9 2.2 TABLE 3 INGREDIENTS W BY WEIGHT LIAL 125 0 2 0 0 C12 GUERBET ALCOHOL 0 0 2 1 ABS 22 22 22 22 SODA ASH IN EXCESS 0.5 0.5 0.5 0.5 OF AMOUNT FOR NEUTRALISATION ALKALINE SILICATE 7 7 7 7 (48%) ALUMINIUM SULPHATE 8 8 8 8 HYDRATE STP 12.5 12.5 12.5 12.5 CALCITE 8.25 7.75 7.75 8 KAOLIN 24.25 23.25 23.25 24

MINOR INGREDIENTS < ---BALANCE TO 100%---- > AND WATER PROPERTIES TOTAL WATER: THEORETICAL 12.5 12.5 12.5 12.5 MEASURED 6.1 10.3 8.2 8.9 pH 9. 5 9. 5 9. 6 9. 6 PENETROMETER (mm) INITIAL 4.0 7.2 5.5 4.9 FINAL 0.9 1.9 1.2 1.6 RATE OF WEAR (g) 7.5 6.3 6.0 7.1 MUSH LOSS (g) 14.0 8.9 9.6 10.6

Claims

CLAIMS: 1. A non-soap detergent bar containing

10 to 60% by weight of non-soap anionic detergent active, at least a majority of which is linear or branched Cs to C22 alkylbenzene sulphonate, the amount of said alkyl benzene sulphonate being at least 10% by weight of the bar; and

5 to 90% by weight of detergency builder, waterinsoluble inorganic filler or a mixture of the two; wherein the bar additionally contains from 0.3 to 10% by weight of at least one alcohol containing 8 to 24 carbon atoms
2. A bar according to claim 1 wherein the amount of said alcohol is in the range from 0.3 to 5% by weight.
3. A bar according to claim 1 wherein at least a majority of said alcohol is linear primary alcohol.
4. A bar according to claim 1 wherein at least a majority of said alcohol is a branched primary alcohol of formula

wherein R1 and R2 are alkyl or alkenyl groups containing in total 8 to 18 carbon atoms.
5. A bar according to claim 1 wherein at least a majority of said alcohol is a secondary alcohol of the formula

wherein R1 and R2 are alkyl or alkenyl groups containing in total 8 to 20 carbon atoms.
6. A bar according to claim 1 wherein said alcohol is a mixture of linear primary alcohol and either or both of secondary alcohol and branched primary alcohol.
7. A bar according to any one of the preceding claims wherein the detergency builder comprises water-soluble detergency builder in an amount which is at least 2% by weight of the bar.
8. A bar according to claim 7 which contains from 2 to 60% by weight of detergency builder.
9. A bar according to claim 8 wherein the water-soluble detergency builder comprises alkali metal orthophosphate, pyrophosphate or tripolyphosphate in an amount which is from 2% to 30% by weight of the bar.
10. A bar according to any one of the preceding claims wherein the bar comprises 2% to 40% by weight of waterinsoluble material.
11. A bar according to any one of the preceding claims which generates a pH in the range from 7.0 to 9.8 when mixed with deionised water at a weight ratio of bar composition: water of 2.5:97.5 and allowed to dissolve as completely as possible at a temperature of 200C.
12. A bar according to claim 11 wherein the pH lies in a range from 7.5 to 9.6.
13. A bar according to any one of claims 1 to 10 which generates a pH in the range from 9.8 to 11 when mixed with deionised water at a weight ratio of bar composition: water of 2.5:97.5 and allowed to dissolve as completely as possible at a temperature of 200C.