GB2083491A - Built detergent bars - Google Patents

Abstract

Built detergent bars containing linear alkyl benzene sulphonate and manufactured by the wet neutralisation route are physically soft. Bars with increased hardness, which is achieved relatively soon after manufacture, are prepared by adding bentonite to the sulphonic acid prior to neutralisation.

Description

SPECIFICATION Built detergent bars FIELD OF THE INVENTION This invention relates to improved built detergent bars. Built detergent bars used for fabric washing and cleaning surfaces should have certain properties to allow efficient manufacturing and performance of their required functions.

The bars must have good strength to ensure they retain their structural integrity during handling after manufacture, transport and use.

Commercial built detergent bars contain detergent active and detergent builder materials together with a number of optional components, for example abrasives, fillers, perfumes, alkaline salts and bleaching agents.

GENERAL DESCRIPTION OF THE INVENTION The invention provides an improvement in built detergent bars comprising from about 7% to about 45% by weight of detergent active material and from about 5% to about 60% by weight of detergency builder. When the detergent active component comprises linear alkyl benzene sulphonates (having from 8 to 16 carbon atoms in the alkyl chain), either alone or in admixture with other actives, and the bar is produced using a wet neutralisation process the product bar is physically soft and therefore of relatively low strength for handling, transport and use.

The built detergent bars to which this invention relates are manufactured by the wet neutralisation process in which all or the major part of the necessary water for the formulation is added to the feedstock detergent active acid prior to neutralisation or to the reacting components during neutralisation with subsequent processing of the mixture to form bars after addition of optional ingredients.

The linear alkyl benzene sulphonates to which this invention specifically relates have the formula RR1CH-C6H4-S03M wherein R and R' are each hydrogen or a linear alkyl group containing 1 to 1 5 carbon atoms, with R and R' together being 7 to 15, C6H4 represents a benzene nucleus and M is a cation providing water soluble properties for the salt. M will usually be selected from potassium, ammonium and sodium, the latter is preferred. The alkyl groups R and R1 together form a linear group; the number of carbon atoms in R and R' depending on the position of attachment of the phenyl group along the linear group.

After manufacture the bars harden over a period of time to a value which aliow the bars to be handled, for example packed, transported and used without effective damage. The period during which the bars harden can generate delays in a production Gine; there is a benefit in moving the product quickly from stage to stage in the manufacturing procedure. The present invention provides a method of manufacturing built detergent bars which have improved hardness for given formulation and this hardness is reached relatively soon after the bar has been produced.

These properties are provided by a method of manufacturing built detergent bars containing from about 7% to about 45% by weight of detergent active material and from about 5% to about 60% by weight of detergency builder, the active component containing at least about 7% (relative to the total bar) of water soluble linear alkyl (C8 to C16) benzene sulphonate comprising the steps of i) admixing the appropriate linear alkyl benzene sulphonic acid with bentonite, ii) adding water with mixing, iii) neutralising the acid with an alkaline material, iv) mixing any additional, optional, ingredients and v) processing the mixture to form bars.

Typically the bar will contain from about 10% to about 30% of the linear alkyl benzene sulphonate.

The amount of bentonite added will preferably be from about 5% to about 50% by weight, preferably from about 10% and below about 40%.

COMPONENTS FOR THE FORMULATION Detergent active and builder components are well characterised in detergent bar technology.

These components are characterised in "Surface Active Agents" by Schwarz and Perry (lnterscience 1949) and volume Il by Schwarz, Perry and Berch (Interscience 1958). The detergent actives usable are found in the general classes of anionic, nonionic, amphoteric, betaine and zwitterionic actives. Specific examples of detergent active usable in admixture with linear alkyl benzene sulphonates are alkane sulphonates, alcohol sulphates, branched alkyl benzene sulphonates, alkyl sulphates, olefin sulphonates, monocarboxylic acid salts and ethoxylated alcohols.

Examples of builder components are: water soluble phosphate salts, e.g. sodium tripolyphosphate, pyrophosphate and orthophosphate; water soluble carbonates, e.g. sodium carbonate; organic builders e.g. sodium nitrilo triacetate, sodium tartarate, trisodium carboxy-methyl oxysuccinate, sodium oxydisuccinate and sodium sulphonated long chain monocarboxylic acids.

Other ingredients, for example silicates, e.g. sodium alkalinesilicate, starch, sodium carboxymethyl cellulose, colouring materials, fluorescors, opacifiers, germicides, perfumes and bleaching agents, are optionally present.

TEST METHODS Bar hardness properties were examined using a penetration method. A bar sample was extruded with a plane surface to allow a series of penetration measurements to be made.

The penetrometer use was a SUR type PNR 8 (Sommer und Runge of Beriin DBR). The penetration needle had a point angle of 9010' and was forced into the plane bar surface under a pressure of 100 g for 10 seconds. The depth of penetration was measured in millimetres (mm); a reading of 4 mm being a standard for an acceptable bar.

The measurements were made daily after manufacture.

EXAMPLES The invention will now be described by way of non-limiting examples.

EXAMPLE I The test formulation used had the composition % by wt Sodium linear alkyl (C12) benzene sulphonate 20 Sodium tripolyphosphate 25 Sodium carbonate 10 Bentonite 35 Water 10 The percentages are quoted in weight of the anhydrous component.

A quantity of the sulphonic acid sufficient to provide the required amount of sulphonate active was mixed with the bentonite for 5 minutes. The formulation water was then added and mixing continued for 10 minutes. The sodium carbonate was then added to neutralise the sulphonic acid and the whole mixed for 10 minutes. After allowing the temperature of the neutralised mixture to fall the sodium tripolyphosphate was added. The whole was then mixed for 15 minutes, milled twice and plodded once with the temperature of the final apertured plate of the plodder maintained at 800 C. The formulation was prepared in batches of 1 5 kg and bars (sample A) were extruded for test.

The method was repeated substituting feldspar for the bentonite; the bars were tested as sample B.

To demonstrate the benefit of the point of addition for the bentonite, bars (sample C) were manufactured using a different order of addition. The sulphonic acid at 350C was first mixed with the sodium carbonate (5 minutes); the formulation water was then added and the whole mixed for 10 minutes. The bentonite and sodium tripolyphosphate were then added in sequence with associated periods of mixing of 10 minutes and 10 minutes for each addition. The bars (sample C) were prepared in the manner described for the previous sample.

Each sample was subjected to daily penetration tests and the period (T) required for the hardness to develop to that found after 7 days was noted. In general it was found the hardness after 7 days approximated to that developed after a longer period. Therefore the period required to reach the 7 day hardness is a good measure of the rapidity of hardening. Resu!ts are given in table I.

TABLE I Sample Initial hardness 7 day hardness T (Days) A 7mm 3mm 1 B 9mm 3mm 3 C 7mm 3mm 3 It is seen sample A not only achieves a satisfactory final hardness but reaches it in a shorter time than sample C.

EXAMPLE II Example I was repeated using a mixture of linear alkyl (cut2) and branched alkyl (C12) benzene sulphonic acids as feedstock in amouns sufficient to provide 10% of each sulphonate active in the final product. Sample D was the bar prepared using bentonite by the method of the present invention, that is as described for bar A in Example I; Sample E was prepared substituting feldspar for bentonite. Sample F was prepared by the process described for Sample C in Example I, i.e. neutralisation of the sulphonic acid before addition of bentonite. The results are given in Table II; the time for a penetration value of 4 mm to be reached is quoted as T (4 mm) in days.

TABLE II Initial 7 day Sample hardness hardness T (days) T (4 mm) D 7.0 mm 1.8 mm 2 1 E 8.2 mm 2.5 mm 6 4 F 6.0 mm 1.8 mm 4 2 It is seen sample D achieves a satisfactory final hardness and reaches it in a shorter time than the other two samples.

EXAMPLE Ill Two sample bars G and H were prepared according to the method of the present invention described in Example I; the compositions were by weight of anhydrous components: G H Sodium linear alkyl (C,2) benzene sulphonate 20 20 Sodium tripolyphosphate 20 20 Sodium carbonate 11 11 Bentonite 5 nil Kaolin 22.5 27.5 Dolomite 10 10 Sodium carboxy methyl cellulose Water 8 8 Minor components to 100% The sulphonic acid, bentonite and kaolin were mixed then the water and sodium carbonate added in sequence with mixing. The remaining components were then added and the whole subjected to mixing and processed into bars. Sample G achieved the necessary commercial hardness more rapidly than Sample H.

Claims (8)

1. A method of manufacturing built detergent bars containing from about 7% to about 45% by weight of detergent active material and from about 5% to about 60% by weight of detergency builder, the active component containing at least about 7% (relative to the total bar) of water soluble linear alkyl (C8 to C,6) benzene sulphonate comprising the steps of i) admixing the appropriate linear alkyl benzene sulphonic acid with bentonite, ii) adding water with mixing, iii) neutralising the acid with an alkaline material, iv) mixing any additional, optional, ingredients and v) processing the mixture to form bars.

2. A method according to claim 1 wherein the bentonite is added in an amount of from about 5% to about 50% by weight.

3. A method according to claim 2 wherein the bentonite is added in an amount of from about 10% to about 40% by weight.

4. A method according to any preceding claim wherein the linear alkyl benzene sulphonate is present in an amount above about 10% by weight.

5. A method according to any preceding claim wherein the linear alkyl benzene sulphonate is present in an amount up to about 30% by weight.

6. A method according to any preceding claim wherein the alkaline material used to neutralise the sulphonic acid is sodium carbonate.

7. A method according to claim 1 substantially as herein described.

8. Detergent bars manufactured by the method of any preceding claim.