ZA200402951B - Detergent bar composition and process for its manufacture. - Google Patents

Description

~ © WO 03/040283 PCT/EP02/11261

DETERGENT BAR COMPOSITION AND PROCESS FOR ITS MANUFACTURE

0 Field of the Invention . The invention relates to det ergent bar compositions for fabric washing and for cleaning sur faces and their manufacture. The invention particularly relat es to laundry bars capable of structuring higher water content but having the requisite mechanical and structural aspects for satisfactory processability and end user properties.

Background to the Invention

Detergent Bars require an ac ceptable physical strength so that they retain their structural integrity during handling, transport and use. The hardness of the bars, at the time of manufacture and subsequently , is an especially important property. Inclusion of certain ingredients to make the bar harder usually results in higher density bars, making the bars considerably smaller and thus less attractive to the consumer and more difficult to handle during fabric washing and sometimes also gritty to feel. Commerc ially available detergent bars contain detergent active components and detergent builders together with conventional components for example abrasives, fillers, perfumes, alkaline salts and bleaching agents. ‘25 Among the various product forms such as liquids, powders, gels, bars, tablets, cakes, compacts etc, in which cleaning compositions are formulated, the bar, tablet or compact forms 4 are economically superior ass compared to the other. The product dosage from the bar is highly controlled in comparison to the ' 30 other forms such as paste, gel or powder. The bar also does not get easily sogged in the presence of water and the active ingredients are not lost. However, for manufacturing of

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products in the solid form it will be necessary to formulate specific compositions and comtrol processing.

GB-A-209 013 discloses detergent bar compositions produced by mixing precursors for aluminosilicate with the bar components under alkaline conditions so that aluminosilicate is formed in situ.

IN-A-171 326 discloses a two component hardening system comprising a polyvalent metal compound and a siliceous material where it is essential that at least one of these ingredients is present before the neutralisation of the active. The polyvalent metal compounds covered in this patent are salts of Aluminium, magnesium, Boron and salts of group IIa and IIb. These bars have improved hardness, rate of wear in use, and mush characteristics.

GB-A-256 647 discloses a route for forming low density bars where starch is premixed with the acid form of detergent active prior to at least partial neutralisation of the active with i silicate. The formulation results in a grit free bar if at least part of the starch is added prior to neutralisation. The starch used in this patent is native starch. Combination of the starch and in-situ generated of silica form low density bars with good processability.

We have found a new route for producing detergent bars having superior properties such ass good processability, in-use LJ properties and improved water retention capacity. This is achieved by generating a st-ructuring system in-situ that is ’ obtained by reacting at least two different polyvalent metal ions with sodium silicate, wherein one of the metal ions is

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WOo03040283 PCT/EP02/11261 calcium or magnesium and the other may be anyone of boron, . aluminum, zinc, calcium or magnesium. . China clay (Hydrated Aluminum Silicate) is a common filler and 5 is incorporated in bars to provide hardness. Removal of china clay fromm the formulation therefore makes the bars softer.

However, removal of china clay is desirable for env ironmental reasons &s china clay has traces of heavy metals. Al so, from an aesthetic point of view, removal of china clay makes the bars brighter. Another object of the present invention is to formulate bars without any china clay and yet retain the bar hardness and improve the brightness of the bar.

According to one aspect of the invention there is provided a detergent bar composition comprising (i) fromm 5% to 60%, preferably from 10% to 50% by weight of detergent active; and (ii) from 2% to 20%, preferably from 5% to 15% by we ight of a strmcturing system being the reaction product of at least two different polyvalent metal ions with sodiuw silicate, wherein one of the metal ions is calcium or magnesium and the other being selected from boron, aluminum, zinc, calcium and magnesium.

According to a second aspect of the invention, there is provided a process for manufacturing a detergent bar composit ion ’ according to the first aspect of the present inventi on, the process comprising the steps: ' 30 (i) in & composition comprising at least some of tle detergent active or its acid precursor, in-situ generation of the structuring system by reacting the at least two different polyvalent metal ions with the sodium silicate before,

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WO O3/640283 PCT/EPOVIIZG © during and/or after partial or complete neutralisation of the acid precursor, one of the metal ions Dbeing calcium or magnesium and the other being selected from boron, ‘ aluminium, zinc, calcium and magnesium ; (ii) optionally, before, during and/or after step (i) addition of other ingredients such as other detergent actives, builders, fillers, and other conventional ingredients; and (iii ) converting the resultant mass into the desired product form.

The percentage by weight of structuring system in the composition is 2 % to 20 %. The structuring system is pref erably formed post neutralization of the acid precursor of the detergent active.

The resultant mass is conveniently converted to the desired product form by any conventional method such ass plodding and stamping.

Detailed Description of the Invention

The Detergent active:

The detergent active is selected from soap or non-soap actives and is preferably anionic and specific detergent. actives used in detergent bar technology are described in literature, for example in Surface Active Agents and Detergents , Volume II by

Schwartz, Perry and Berch (Interscience Publishers, N.Y. 1958).

Specific examples of suitable anionic actives useful in this : invention are soap or non soap selected from limear and branched alkyl benzene sulphonates, alkane sulphonates, secondary alcohol ’ sulphates, primary alcohol sulphates, alpha ole £in sulphonates, alkyl ether sulphates, fatty acyl ester sulphonates, alkyl carboxylates and mixtures of these.

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rE WO 03/040283 PCT/EP02/11261 . When the detergent active is soap, the term total fatty matter, usually abbreviated to TFM is used to denote the percentage by

R weight of fatty acid and triglyceride residues present in soaps without taking into account the accompanyirag cations.

For a soap having 18 carbon atoms, an accompanying sodium cation will generally amount to about 8% bys weight. Other cations may be employed as desired for example zinc, potassium, 100+ magnesium, alkyl ammonium and aluminium.

The term soap denotes salts of carboxylic fatty acids. The soap may be derived from any of the triglycerides conventionally used in soap manufacture - consequently the carboxylate anions in the scap may contain from 8 to 22 carbor atoms.

The other detergent active compounds may be anionic, nonionic, cationic, zwitterionic or amphoteric surfactants, or mixtures thereof as are well known to those skilled in the art can also be incorporated in the formulation. Especia lly preferred are compositions in which the anionic detergent active comprises of alkyl benzene sulphonate (LAS) .

The detergent active is present in quantiti es normal for detergent bars, e.g. 5 to 60% by weight, preferably 10-50, more preferably about 12 to 45% by weight of thes total bar composition.

The in-situ generation of the structuring ssystem is done using 1 3:0 silicate which is preferably sodium silicat-e of the type having a molar ratio of 8i0,:M,0 of less than 4, more preferably less than 3, most preferably between 3 and 1.

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Builders:

The detergency> builders used in the formulation are preferably ’ inorganic and suitable builders include, for example, alkali metal aluminosilicates (zeolites), alkali metal carbonate, sodium tripoly phosphate (STPP), tetrasodium pyrophosphate (TSPP), citrattes, sodium nitrilotriacetate (NTA) and combinations of these. Builders are suitably used in an amount ranging from O to 30%.

Inorganic par ticulates:

Inorganic par ticulate phase is not an essential ingredierat of the formulati on but may be incorporated especially for hard surface cleaning compositions. preferably, the particulate phase comprisses a particulate structurant and/or abrasive which is insoluble in water. Suitable inorganic particulates can be selected from, particulate zeolites, calcites, dolomites » feldspars, si. licas, silicates, other carbonates, bicarbormates, borates, sulphates and polymeric materials such as polyethylene o

The most preferred inorganic particulates are calcium ca rbonate (as Calcite) , mixtures of calcium and magnesium carbonat es (as dolomite), sodium hydrogen carbonate, borax, sodium/pota ssium sulphate, zeolite, feldspars, talc, koalin and silica.

Calcite, tal<, kaolin, feldspar and dolomite and mixtures thereof are particularly preferred due to their low cost and : colour. '

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BE © WO 03/040283 PCT/EP02/11261

Other conventional inorganic particulate structurants such as . alumino silicate may be generated in situ or readily available forms can be incorporated. .

Other additives:

Other additives such as one or more water insoluble particulate materials such as polysaccharides such as starch or modified starches and celluloses may be incorporated.

Minor additives:

Minor and conventional ingredients preferably selected from enzymes, antiredepositiom agents, fluorescers, colour, preservatives and perfumes, also bleaches, bleach precursors, bleach stabilisers, sequestrants, soil release agents (usually polymers) and other polymers may optionally be incorporated up to 10 wt%.

Illustrations of a few non-limiting examples are provided herein showing comparatiwe results of the composition prepared by the present invention . The composition details and their results are described in Tables 1 to 3 with reference to bars.

The processing of the detergent bar was done as explained "below.

EXAMPLES:

Example 1:

Process for preparing the detergent bar: ) a. Conventional Process:

A batch of 6 kg detergent bar was prepared by taking 1.2 kg of linear alkyl benzene sulphonic acid in a sigma mixer and neutralising it with 600 gms of sodium carbonate. In-situ aluminosilicate was generated by the reaction of 180 gm aluminium sulphate and 120 gm sodium silicate. Other ingredients

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such as 720 gms of sodium tripolyphosphate (STPP) builder, approximately 3 kg of fillers, water and minor ingredients were also added. These were thoroughly mixed and plodded in a conventional manner (Example la) . \ b. Process according to the invention:

A batch of 6 kg detergent bar was prepared by taking 1.2 kg of linear alkyl benzene sulphonic acid in a sigma mixer and neutralising it with 600 gms of sodium carbonate. The structuring system was generated after the complete neutralisation of the active by reacting 30 gm Aluminium

Sulphate, 180 gm Alkaline Silicate and 90 gm Calcium Chloride in the mixer. Other ingredients such as 720 gms of STPP builder, approximately 3 kg of fillers, water and minor ingredients were also added. These were thoroughly mixed and plodded in a conventional manner (Example ib).

Other structuring systems for comparison were generated as per the details below. In all the formulations the total structuring ingredients were maintained close to 5% of the total weight of the formulation.

Example lc: In-situ calcium silicate generated by the reaction of 180 gm sodium silicate

And 120 gm calcium chiloride

Example 14: In situ alumino silicate generated by the reaction of 30g aluminum sulphate and 30g alkaline silicate and postdosing calcium silicate generated by i reacting 90g calcium chloride and 150g alkaline silicate. )

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E © WO 03/040283 PCT/EP02/112261

S

Example le: Post-dosing calcium aluminosilicate generated by . the recaction of 30 gm Aluminum Sulphate, 180 gm

Alkali ne Silicate and 90 gm Calcium Chloride. . Example 1f: In-situ calcium boro-silicate generated by the reacti on of 30 gm Boric Acid, 210 gms of Alkaline silicate and 72 gm Aluminium Sulphate.

The bars prepare-d by the process mentioned above were tested for different physical and in use properties by the following procedure and th-e formulation details and the data are prese=nted in Table 1.

Determination of hardness of the bar

Bar hardness for a given moisture level is a direct indicat-or of how well the bar is structured. A penetrometer was used to get an estimate of the hardness and the yield stress of the detergent bars, based on the depth of penetration of a needle.

Higher the penetration, less the hardness and the yield stircess and vice-versa. Measurements are made by allowing a needle with a cone angle of 9° degrees to fall under a set weight of 50 gms for 5 seconds ora top of a flat surface of the bar. The deptth of penetration is r-eported in mm.

Water retention:

Water retention ability of a bar is quantified by measuring the water activity in the bar. This measurement is carried out on

AW Sprint model from Novasina of Switzerland. A grated sample ' of the bar is equilibrated at a set temperature, and the relative humidity calculation is done by the instrument which indicates the water activity. Lower water activity at a given moisture level indicates better ability of the bar to retain water and hence better structuring in the bar.

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Method for mush estimation

The mush refers to the paste like layer formed on the bar surface upon contact with water. This laser is useful for easy application of the bar on the fabric, however, excessive ' formation of mush is perceived as wastage (low economy) by the consumer.

Test Procedure 1) Remove the surface unevenness such as flutes/logo etc, by planing the bar using a carpenter's plane. 2) Weigh the planes bar (W, g) 3) Immerse section of bar area (50 cm’ ) of above planed bar in 250 ml of distilled water for 20 minutess. 4) At the end of 20 minutes, remove the bar from the water pool and drip dry for some time. 5) Scrape the surface exposed to water gently and collect the loosely adhering material (cling mush) in a pre-weighed petri- dish (P g). Weigh the dish and cling mussh together (W:; g) and find the weight of the cling mush (Wy; g) by difference in weights (Wix= W.-P). 6) The bar loss to solution was measured by measuring the weight gained by the water in the beaker.

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~ © WO 03/040283 PCT/EP02/11261

Table 1 [3

Composition of | Ex Ex Ex Ex 1d EX le Ex 1f : Ingredients, Ia 1b lc wt %

Fillers* 46. | 46.3 | 46.3 | 46.3 46.3 46.3 3

Structuring In- In- In- In-situ Post-dosed | In-situ "| Ingredients, sit | situ | situ |Al-Si, . Ca-Al-Si (in-situ/post- |u Post-dosed dosed) Ca-Si

Aluminum 3 0.5 0.5 0.5

Sulphate

Alkaline 2 3 3 3.0 3 3.5

Silicate

Calcium 1.5 2 1.5 1.5 1.2

Chloride

EEE A EN Co

Moisture Targetted at 10 % =~ Actual 10 £ 0.3 %

Penetration, 1.9 1.35 1.69 1.88 2.28 1.48 mm @ 30 C 2

Water Activity | 0.7 0.65 0.692 0.657 23 8 ® Builders used were Sodium carbonate anc STPP. & Fillers used were calcite, calcium hydroxide and washed china clay.

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Lower the penetxation, higher the hardness. We find from the penetration measurements that the Calcium-alumino Silicate structured (Ex 1b) bar is harder than in-situ alumino silica te } structured bars (Ex la) and in-situ calcium silicate structured bars (Ex 1c). Also, the bars according to the invention where the Calcium Alurnino-silicate is generated in- situ (Ex. 1b) is significantly harder as compared to the bars where only

AluminoSilicate is generated in-situ and Calcium Silicate is post-dosed (Ex. 1d) and the bars where Calcium Alumino-silicate is post-dosed (Ex. le). This reinforces the fact that the structuring has to be necessarily generated in-situ.

Lower water act ivity is an indication of lower weight loss during storage. The data in Table 1 shows that the bars according to the invention (Ex. ib) have a lower water activity as compared to the bars with conventional Alumino-silicate structuring (Ex. la). This indicates that the bars according to this invention will lose less water during storage.

This invention is not restricted to only one combination of metal ions, i.e., calcium and Aluminum. More than one combination of metal ions can react with sodium Silicate to generate the structuring. Example 1f demonstrates one such case. In this case, a boron containing salt, boric Acid, amd a calcium containing salt, calcium chloride, react with Alkaline silicate to gemerate calcium boro-silicate structuring in-situ.

This structuring also improves hardness of the bar and reduces ) the water activity.

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Claims (8)

"CLAIMS

1. A detergent bar comprising: (1) from 5% to 60% by weight of detergent active; and (ii) from 2% to 20% by weight of a structuring system being the reaction product of at least two different polyvalent metal ions with sodium silicate, wherein one of the metal ions is calcium or magnesium and the other being selected from boron, aluminum, zinc, calcium and magnesium.

2. A detergent bar according to claim 1, comprising from 10% to 50% by weight of detergent active and from 5% to 15% by weight of a structuring system.

3. A detergent bar according to either claim 1 or claim 2, wherein the sodium silicate is of the type havi ng a molar ratio of Si0; : Na,O of less than 4.

4. A detergent bar according to claim 3, wherein the molar ratio of SiO, : Nay0 is between 3 and 1.

5. A detergent bar according to any one of claims 1 to 4, wherein the bar does not contain any China clay .

6. A process for manufacturing a detergent bar composition according to claim 1 or claim 2, the process commnprising the steps: (i) in a composition comprising at least some of the detergent active or its acid precursor, in-situ generation of the structuring system by reacting the at least two different polyvalen.t metal SUBSTITUTE SHEET (RULE 26) Amended Sheet — 11-02-2005 ions with the sodium silicate before, during and/or after partial or complete neutralisation of the acid precursor; (ii) optionally, before, during and/or after step (i) addition of other ingredients; and (iii) converting the resultant mass into the desired product form.

} 7. A process according to claim 6, wherein in step (ii), the other ingredients are selected from other detergent actives, builders, fillers, and other conventional ingredients.

8. A process according to either claim 6 or claim 7, wherein the structuring system is generated post neutralisation of the acid precursor of the detergent active. SUBSTITUTE SHEET (RULE 26) Amended Sheet — 11-02-2005