GB2291067A - Detergent Composition - Google Patents

Abstract

A non-soap detergent bar containing detergent active, builder, starch and clay at a level of not more than 10wt% exhibits low mush and rate of wear characteristics and has a relatively low density. The detergent active may be alkylbenzene sulphonate or primary alkyl sulphate and may include alkyl ethoxylates, ether sulphates, alcohol sulphates, fatty acid ester sulphonates, ethoxylated alcohol sulphates, betaines, amino oxides and fatty acid isethionates. The builder may be a phosphate, carbonate or an organic material. The starch may be from rice, potato, corn, tapioca or wheat barley and is preferably pregelatinised starch. The clay is smectite, montmorillonite saponite or hectorite. Preferably bentonite.

Description

DETERGENT COMPOSITION This invention relates to built non-soap detergent (NSD) bars. Such non-soap products are very widely used in parts of the world for the hand-washing of fabrics and also for the cleaning of fixed surfaces. They generally contain non-soap detergent active, detergency builder (frequently phosphate salts) and water-insoluble filler as the three main components of the composition.

A disadvantage of such non-soap bars over soap-containing bars is that the former tend to have a higher density, ie this results in a decrease in the effective surface area for a given weight and shape. (from GB 1333 042). Thus, there is a continuing need for bars which have a reduced density yet maintain a commercially acceptable rate of wear. Indeed it is known that increasing the level of active in a bar can result in a reduction in the overall density from about 1.8 to about 1.5 gcm3. It is also known that starch can be added to a formulation to decrease the density thereof.

In the search for components which may be added to detergent bar formulations to reduce the density, unexpectantly, we have found that bar properties are improved, ie. rate of wear decreases and amount of mush decreases, if a bar formulation comprises both starch and clay.

Thus, according to the present invention there is provided a built detergent bar composition comprising: i) 20 to 50 wtt of a non-soap detergent active; ii) 5 to 60wt% of a detergency builder; iii) a starch; and iv) a clay.

Deteraent Active As already mentioned, the composition includes non-soap detergent active in an amount from 20 to 50wt% of the overall composition. A particularly envisaged range is from 25 to 40wt%. The detergent active may be an anionic detergent active, a nonionic detergent active or a mixture of both. If the composition of the invention contains a nonionic detergent active this is preferably present at a level up to 4Owt% of the total detergent active.

Anionic detergent actives of the present invention are preferably either or both of: alkylbenzene sulphonates of formula RC6 H4 SO3M and primary alkyl sulphates, also known as primary alcohol sulphates, of formula ROSO3M wherein in each formula R is a linear or branched primary alkyl or alkenyl group containing 8 to 18 carbon atoms, preferably 10 to 18 carbon atoms, and M is a cation such that the detergent active is water soluble.

In primary alkyl sulphates R will frequently be a linear alkyl of 8 to 18 carbon atoms, preferably of 10 to 16 or 18 carbon atoms. In alkylbenzene sulphonates R may be a linear or branched alkyl of 8 to 18 carbon atoms and preferably contains 8 to 16 carbon atoms.

The detergent active may consist solely of primary alkyl sulphate. However, it is envisaged that the detergent active will most preferably be alkylbenzene sulphonate (either branched or linear) or a mixture of alkylbenzene sulphonate and primary alkyl sulphate in a weight ratio ranging from 3:1 to 1:9.

Other detergent actives which may be used in lesser amount as coactives include Cl2-Cl8 alkyl ethoxylates with 1 to 12 EO groups, ether sulphates, alkane sulphonates, secondary alcohol sulphates, oleo in sulphonates, fatty acid ester sulphonates, ethoxylated alcohol sulphates, betaines, amine oxides and fatty acid isethionates.

Fatty acyl amides and alkanolamides which are polar nonionic detergents, may also be employed. A suitable amount of these polar nonionic detergents is 5% by weight of the bar composition.

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, it does not exceed 2% by weight of the bar composition.

Deteraenev Builder Bars according to the present invention contain from 5 to 60wt% of detergency builder, preferably from 7 to 35%. The detergency builder, may be a water-soluble builder, waterinsoluble builder, or a mixture of the two.

Examples of water-soluble builder components are: water soluble phosphate salts, eg. sodium and potassium, tripolyphosphate, pyrophosphate and orthophosphate; water soluble carbonates, eg. sodium carbonate; organic builders, eg. sodium nitrilotriacetate, sodium tartrate, sodium citrate, trisodium carboxymethyloxysuccinate, sodium oxydisuccinate, sodium sulphonated long-chain monocarboxylic acids, polyacrylates and oxidised polysaccharides. Preferred forms of this invention are bars in which the builder comprises sodium tripolyphosphate. If this breaks down it is believed to improve the hydration capacity of the bar making it higher without unduly effecting the building performance of the bar.

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, eg. 5 to 40%.

Starch Preferably the starch is selected from rice, potato, maize (corn), tapioca and wheat-barley and, most preferably, is a pregelatinised starch.

Clav In a preferred embodiment the clay is selected from smectite, montmorillonite saponite and hectorite as defined in Clay Mineralogy". F S Grim, 2nd Edition, 1968 (McGraw-Hill Inc).

A suitable smectite clay is bentonite. An alternative is Volclay available from American Colloid Company.

The level of starch and clay are preferably within the range 3 to 25wt% and 3 to lOwt% respectively. Preferably the weight ratio of starch to clay is at least 1:1 and, most preferably in the range 2:1 to 3:1.

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. If a water-insoluble detergency builder is present, this will also contribute to the content of water-insoluble material.

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 disclosure are preferably used in the bars of the present invention and contribute to the content of water-insoluble material.

Other inaredients 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 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 158 by weight of such material, better at least 2% or even at least 7.5 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 carboxymethylcellulose, starches, colouring materials, fluorescers, polyvinylpyrrolidones, 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.

Linear fatty alcohols (without ethoxylation) such as coconut alcohol may be incorporated in bars according to this invention if desired. Some fatty alcohol is likely to be included in commercial supplies of primary alkyl sulphate, since alcohol sulphate invariably contains some unsulphated material, and there can also be decomposition to fatty alcohol during bar manufacture. However, there is no necessity to incorporate such linear fatty alcohol in addition to the amount, if any, which is present as an impurity. The level of impurity, which can be up to 15, arises from impurity in the conversion to the alcohol sulphate as well as breakdown which occurs during bar manufacture.

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 per. 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 1500 to 300C will be adequately accurate.

Depending on the intended pH, other less alkaline salts may be introduced to provide further control of the pH eg. sodium carbonate may be replaced by sodium bicarbonate. 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 present, for example 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. The starch and clay are added directly after neutralisation before the fillers. 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 milling, extrusion and bar stamping.

Neutralisation is preferably effected by a carbonate (usually soda ash) which is added to the acidic mixture. Water can be added to catalyse this neutralisation. 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.

Examples In the following examples bars with the given compositions were manufactured as described above. A typical procedure is outlined below.

STP (1000g) and soda ash (2260g) were added to a pre-warmed Beken mixer and mixed for two minutes. 2300g of linear alkylbenzene sulphonic acid (Petrelab 550) was mixed with sulphuric acid (360g), added to the mixer and mixed for a further half minute. The mix at this stage was a dry, crumbly dough. Water (lOCOgj was then added and mixed for one minute. Thereafter, Amijel starch (1COGS) was added and mixing continued for 5 minutes.

Bentonite (lOOOg) was then added and after 2 minutes mixing, aluminium sulphate hydrate (1400g) was added followed, after two further minutes, by primary alcohol sulphate (3943g) and mixing continued for a further 8 minutes. The Beken mixer was heated with steam to keep the temperature of the mix in excess of 650C.

Finally, silica (400g), STP (2000g), calcite (1610g), sodium sulphite (1600g), coconut fatty alcohol (200g) and minors such as perfume were added sequentially.

After the addition of all the ingredients the NSD dough was mixed for three minutes before it was milled, using a three roll mill, then plodded using a conventional plodder to produce bars.

The bars were tested for integrity when wet, rate of wear, foam generated in use as well as bar hardness and density.

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 either for two or 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 then weighted.

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

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 200C 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 a mixture of primary alkyl sulphate and linear alkyl benzene sulphonate as anionic detergent.

Formulations of the bars and their observed properties are given in Table 1 where: PAS is sodium salt of coconut alcohol sulphate.

LAS is a Cw1 -C-1 linear alkylbenzene sulphonate.

OFA is a coconut fatty acid.

STP is sodium tripolyphosphate.

Table I

Example A# B# C# 1 2 LAS 12 14 14 14 14 Coco-PAS 18 21 21 21 21 CFA 3 3 3 3 3 Sulphuric acid 1.8 3.6 3.6 3.6 3.6 Soda ash 3 - - - - STP 15 12 12 12 12 Calcite 17.6 16.6 16.6 11.6 3 Al sulphate hydrate 7 5 5 5 5 Silica 2 4 4 4 4 Sodium sulphite 10 ~ ~ . ~ Bentonite - 5 - 5 5 STARCH Amijela - 5 5 13.6 b Remy rice - - - - - Minors + water To To To To To 100% 100% 100% 100% 100% Properties pH 9.3 Density 1.7 1.59 1.54 1.48 1.44 Mush loss 9.5 10.8 10.1 9.4 9.1 Rate of wear 5.4 5.2 4.8 4.1 3.2 comparative examples A# - D# commercially available bars a pregelatinised cold water dispersable starch (AMIJEL ex Cerestar) b BLM7 ex Remy Belgium ) commercially available materials ex National Starch.

Table II

Example D# 3 4 5 6 7 LAS 12 12 14 14 14 14 Coco-PAS 18 18 21 21 21 21 CFA 1 1 1 1 1 1 Sulphuric acid 1.8 3.6 3.6 3.6 3.6 3.6 Soda ash 3 - - - - STP 15 12 12 12 12 12.5 Calcite 19.6 3 1 - - Al sulphate hydrate 7 5 5 5 5 5 Silica 2 2 4 5 5 5 Sodium sulphite 10 - - - - Bentonite 0 5 5 5 5 5 STARCH Amijeld - - 14 - - Maize c - - - 14 - Tapiocad - - - - 14 Remy rice - 21.6 - - - 14 Minors + water To To To To To To 100% 100% 100% 100% 100% 100% Properties pH 8.6 Density 1.7 1.43 1.44 1.53 1.47 1.47 Mush loss 12.6 9.8 9.8 12.2 12.8 11.9 Rate of wear 6.9 2.3 2.9 5.6 5.7 6.0 The results demonstrate that the rate of wear of a bar comprising both bentonite and starch is lower (ie. the bar is more economical) than that of a comparable commercially available bar or of a bar comprising eIther bentonite or starch.

Bars comprising both bentonite and starch, where the ratio of starch to bentonite is greater than 1:1, show even greater reductions in rate of wear.

The advantage of using a pregelatinised starch over a standard starch can be seen from the results for examples 4 when compared to those for examples 5 to 7.

The results also demonstrate the reduction in bar density achieved when bars comprise a mixture of bentonite and starch when compared with bars comprising bentonite or starch alone.

Furthermore the results also show that mush loss is reduced when the ratio of starch to bentonite is increased.

Claims (5)

1. A built detergent bar composition comprising: i) 20 to 50 wt of a non-soap detergent active; ii) 5 to 60wt of a detergency builder; iii) a starch; and iv) a clay.

2. A composition according to claim 1 wherein the starch and clay are respectively present in an amount from 3 to 25wit and 3 to l0wt%.

3. A composition according to claims 1 or 2 wherein the weight ratio of starch to clay is at least 1:1.

4. A composition according to any preceding claim in which the starch is selected from rice, potato, maize (corn), tapioca, wheat-barley and pregelatinised starch.

5. A composition according to any one of claims 1 to 3 in which the clay is selected from smectite, montmorillonite saponite and hectorite.