GB2083490A - 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 are prepared by adding bentonite and/or kaolin during processing.

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 a 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 1 6 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 the invention specifically relates have the formula R R1 CH-C6H4-S03 M where 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 1 5, C6 H4 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 R' 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 allow the bars to be handled, for example packed, transported and used without effective damage. The present invention provides a method of manufacturing built detergent bars which have improved hardness for a given formulation.

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 C,6) benzene sulphonate comprising the steps of i) neutralising the appropriate linear alkyl benzene sulphonic acid with an alkaline material; ii) adding all or the major part of the formulation water during or after neutralisation; iii) mixing any additional, optional, ingredients; iv) processing the mixture to form bars, characterised in that bentonite or kaolin or a mixture thereof is added at one or more of stages (i), (ii) and (ii).The amount of bentonite and/or kaolin added will be sufficient to harden the bar and will preferably be from about 5% to about 50% by weight, preferably from about 10% and below about 40%.

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

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 Schwartz and Perry (Interscience 1949) and volume II by Schwartz, 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, eg sodium tripolyphosphate, pyrophosphate and orthophosphate; water soluble carbonates, e.g. sodium carbonate; organic builders eg sodium nitrilo triacetate, sodium tartarate, trisodium carboxy-methyl oxysuccinate. sodium oxydisuccinate and sodium sulphonated iong chain moncarboxylic acids.

Other ingredients, for example silicates, eg sodium alkaline silicate, 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 used was a SUR type PNR 8 (Sommer und Runge of Berlin DBR). The penetration needle had a point angle of 9010r 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 1 The test formulation used had the composition % by weight 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 (at 350C) sufficient to provide the required amount of sulphonate active was mixed with, and neutralised by, the sodium carbonate for 5 minutes. The formulation water was then added and mixed for 10 minutes. After allowing the temperatures of the neutralised mixture to fall the bentonite and sodium tripolyphosphate were added in sequence with a period of 10 minutes mixing after addition of the bentonite. The whole was then mixed for 10 minutes, milled twice and plodded once with the temperature of the final apertured plate of the plodder maintained at 800C. The formulation was prepared in batches of 1 5 Kg and bars (sample A) were extruded for test.

The method was repeated substituting kaolin, feldspar and calcite for the bentonite; the bars were tested as sample B, C and D respectively.

Each sample was subjected to daily penetration tests and the hardness after 7 days was noted. In general it was found the hardness after 7 days approximated to that developed after a longer period.

Results are given in Table I.

TABLE I Sample Initial hardness 7 day hardness A 7mm 3mm B 8 mum 3 mum C 14mm 5 mm D 13mm 5mm It is seen Samples A (bentonite) and B (kaolin) achieve a commercially acceptable hardness after 7 days, in distinction from Samples C and D.

EXAMPLE II Test bars E s F were prepared with the composition quoted below.

% by weight E F Sodium linear alkyl (C12) benzene sulphonate 17 1 7 Sodium tripolyphosphate 15 15 Sodium carbonate 12 17 Kaolin 20 15 Calcite 25 25 Sodium carboxyl methyl cellulose 1 1 Water 8 8 Minor components to 100 Percentages are quoted in weight of the an hydros components.

A quantity of the sulphonic acid sufficient to provide the required amount of sulphonate was mixed with the water and neutralised by mixing with the sodium carbonate and one third (1/3) of the tripolyphosphate for 5 minutes. The remainder of the tripolyphosphate, kaolin and calcite were then added together with the minor components.

After mixing for 10 minutes the whole was milled twice and plodded (aperture plate at 800 C) to form bars.

Bars E 8 F were both acceptable products but substitution of the kaolin with calcite gave bars which remained soft.

EXAMPLE Ill Example I was repeated using as feedstock a mixture of linear alkyl (C,2) and branched alkyl (C12) benzene sulphonic acids sufficient to provide 10% by weight of each of the sulphonate actives in the final product. Test bars G 8 H were prepared containing 35% by weight bentonite and kaolin respectively, the results of hardness measurements are given in Table II.

TABLE II Bar Initial hardness 7 day hardness G 6 mm 1.8 mm H 5.2 mm 1.7 mm EXAMPLE IV Example Ill was repeated using a mixture of linear alkyl (C,2) benzene sulphonic acid and primary (coconut) alcohol sulphate and 35% bentonite. The bar (J) had an initial hardness of 6 mm and a 7 day hardness of 1.2 mm.

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 C16) benzene sulphonate, comprising the steps of i) neutralising the appropriate linear alkyl benzene sulphonic acid with an alkaline material; ii) adding all or the major part of the formulation water during or after neutralisation; iii) mixing any additional optional, ingredients; iv) processing the mixture to form bars, characterised in that bentonite or kaolin or a mixture thereof is added at one or more of stages (i), (ii) and (iii) in an amount sufficient to harden the bar.

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

3. A method according to claim 2 wherein the bentonite and/or kaolin 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.