WO2004018608A1

WO2004018608A1 - Process for detergent bar manufacture

Info

Publication number: WO2004018608A1
Application number: PCT/EP2003/007403
Authority: WO
Inventors: Vija B Krishna; Benjamin Rajapandian; Glyn Roberts
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Limited
Priority date: 2002-08-20
Filing date: 2003-07-09
Publication date: 2004-03-04
Also published as: AU2003290380A1; BR0313071A; CN1675349A

Abstract

The invention provides a process for the preparation of detergent bars not containing clay, comprising the steps ofa) reacting the precursor of a detergent active with an alkaline material;b) adding a mixture of at least one polyol and a boron containing compound;c) adding sodium alumino silicate or generating in situ sodium alumino-silicate by allowing a source of monomeric aluminium to condense with silicate anion;d) adding if desired other detergent actives, builders and minor ingredients; andconverting the product into bars by conventional method. The resulting bar includes 5-70% by weight of detergent active, 0.5 to 30% by weight of boron- polyol gel, 1-15% by weight of aluminosilicate, and water.

Description

PROCESS FOR DETERGENT BAR MANUFACTURE

Field of the invention

The invention relates to a process for the preparation of nil china clay detergent bars with good physical and sensorial attributes. Detergent bars may be used for cleaning fabric or hard surfaces or for personal wash.

Background of the invention Detergent bars require an acceptable 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.

The binders and fillers used in detergent bars are typically minerals which generally exhibit wide variability in quality, by virtue of the fact that they are mined. The minerals are also responsible for the unattractive base colour of detergent bars and contribute significantly to mush and sog during use. The low moisture content coupled with the use of high proportion of minerals result in bars with high density making them considerably smaller. Commercially available detergent bars contain detergent active components and detergent builders, fillers, structurants, hardeners together with optional components for example abrasives, perfumes, colour and bleaching agents.

Commercial hard surface cleaning compositions typically comprise one or more surfactants and a plurality of abrasives dispersed therein. Combinations of these together with electrolytes are generally used to form a suspending system as is well known in the art. In fabric washing where the active constitutes predominantly non-soap surfactants it is important to deliver superior sensory properties such as lather, bar feel, skin feel, colour of the bar, without altering the processability and physical properties of the bar.

It would be essential to process the formulations using the existing equipment to enable products to be processed by the conventional methods of manufacture and without altering the through-put.

Our copending application 183/MUM/2001 teaches a process for the preparation of low density bars with high water content by reacting the precursor of the detergent active with an alkaline material; adding a mixture of at least one hydroxy bearing polymer and a boron containing compound, generating in situ sodium aluminosilicate by allowing a source of monomeric aluminium to condense with silicate anion adding if desired other detergent actives, builders, fillers and minor ingredients and converting the product into bars by conventional method.

The prior art discloses polymers such as polyvinyl alcohol, poly vinyl acetate and other polymers with a degree of polymerisation in the range of 100-5000 with reactive hydroxyl or amino groups. However, it does not teach the use of polyols along with boron which when generated as a boron-polyol gel is capable of eliminating the minerals required for bar hardening. The use of these minerals affects the product quality.

But now it has been found that using a combination of a polyol with a boron-containing compound the need to use any mineral or clays in the formulations can be totally eliminated. It has been possible to formulate bars with no minerals at all or with extremely low levels which has a significant influence in improving product quality and it improves the colour of the bar significantly.

Description of the invention

The present invention relates to a process for the preparation of bars without clay comprising the steps of: a. reacting the precursor of a detergent active with an alkaline material; b. adding a mixture of at least one polyol and a boron containing compound; c. adding sodium aluminosilicate or generating in situ sodium aluminosilicate by allowing a source of monomeric aluminium to condense with silicate anion; d. adding if desired other detergent actives, builders and minor ingredients; and e. converting the product into bars by conventional method, the ingredients needed in the process being incorporated in such amounts as to provide a bar composition comprising: from 5 to 70% by weight of detergent active from 0.5 to 30% by weight of boron-polyol gel from 1-15% by weight of aluminosilicate from 5-20% by weight water from 0-30% by weight detergent builder from 0-60% by weight inorganic particulates .

It is particularly preferred that the polyol comprises of more than two hydroxyl groups. Detailed description of the invention

It is essential for the process of the present invention that for the manufacture of low density detergent compositions with high levels of water, to generate in situ boron polyol gel along with aluminosilicate as the structuring system.

Boron-polyol gel :

The boron - polymer gel is generated by reaction of a boron containing compound such as borax or boric acid with a polyol preferably with more than two hydroxyl groups selected from glycerol, sorbotol , xylitol, mannitol, monosaccharides, disaccharides , or any other polylol with reactive hydroxyl or amino (electron donating) groups. The reaction is preferably effected in the presence of a cross-linking agent. The cross- linking agent could be an electron accepting metal or metal- like atom such as boron. The reaction between the boron containing compound and the polyol is preferably carried out in a mole ratio from 0.1 to 15. The boron-polyol gel is preferably generated after forming the detergent active.

Alumino-silicate structuring system:

The inorganic particulate structurant alumino silicate is generated in situ using a source of monomeric aluminium to condense with silicate anion. The preferable components used for the generation of the structurant are aluminium sulphate and alkaline sodium silicate. It is also possible to incorporate readily available sodium alumino-silicate into the formulation. It is highly preferred that the aluminosilicate is generated or incorporated after the formation of boron-polyol gel. The invention is carried out in any mixer conventionally used in soap/detergent manufacture and is preferably a high shear kneading mixer. The preferred mixers include ploughshare mixer, mixers with kneading members of sigma type, multi wiping overlap, single curve or double arm. The double arm kneading mixers can be of overlapping or tangential in design. Alternatively the invention can be carried out in a helical screw agitator vessel or multi head dosing pump/high shear mixer and spray drier combinations as in conventional processing.

Detergent active:

The detergent active used in the process may be soap or non- soap surfactants. The term total fatty matter, usually abbreviated to TFM is used to denote the percentage by weight of fatty acid and triglyceride residues present in soaps without taking into account the accompanying cations.

For soap having 18 carbon atoms, an accompanying sodium cation will generally amount to about 8% by weight. Other cations may be employed as desired for example zinc, potassium, 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 soap may contain from 8 to 22 carbon atoms.

The soap may be obtained by saponifying a fat and/or a fatty acid. The fats or oils generally, used in soap manufacture may be such as tallow, tallow stearines, palm oil, palm stearines, soya bean oil, fish oil, castor oil, rice bran oil, sunflower oil, coconut oil, babassu oil, palm kernel oil, and others. In the above process the fatty acids are derived from oils/fats selected from coconut, rice bran, groundnut, tallow, palm, palm kernel, cotton seed, soyabean, castor etc. The fatty acid soaps can also be synthetically prepared (e.g. by the oxidation of petroleum or by the hydrogenation of carbon monoxide by the

Fischer-Tropsch process) . Resin acids, such as those present in tall oil, may be used. Naphthenic acids are also suitable.

Tallow fatty acids can be derived from various animal sources and generally comprise about 1-8% myristic acid, about 21-32% palmitic acid, about 14-31% stearic acid, about 0-4% palmitoleic acid, about 36-50% oleic acid and about 0-5% linoleic acid. A typical distribution is 2.5% myristic acid, 29% palmitic acid, 23% stearic acid, 2% palmitoleic acid, 41.5% oleic acid, and 3% linoleic acid. Other similar mixtures, such as those from palm oil and those derived from various animal tallow and lard are also included.

Coconut oil refers to fatty acid mixtures having an approximate carbon chain length distribution of 8% C₈, 7% Cio, 48% C_X2, 17% Ci4, 8% Ci₆, 2% Ciβ, 7% oleic and 2% linoleic acids (the first six fatty acids listed being saturated) . Other sources having similar carbon chain length distributions, such as palm kernel oil and babassu kernel oil, are included within the term coconut oil .

Fatty acid:

A typical fatty acid blend consisted of 5 to 30% coconut fatty acids and 70 to 95% fatty acids ex hardened rice bran oil. Fatty acids derived from other suitable oils/fats such as groundnut, soybean, tallow, palm, palm kernel, etc. may also be used in other desired proportions. Non-Soap detergents:

The composition according to the invention will preferably comprise detergent actives which are generally chosen from both anionic and nonionic detergent actives.

Suitable anionic detergent active compounds are water soluble salts of organic sulphuric reaction products having in their molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphuric acid ester radicals and mixtures thereof.

Examples of suitable anionic detergents are sodium and potassium alcohol sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium and potassium alkyl benzene sulphonates such as those in which the alkyl group contains from 9 to 15 carbon atoms; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulphates; sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof. The preferred water-soluble synthetic anionic detergent active compounds are the alkali metal (such as sodium and potassium) and alkaline earth metal (such as calcium and magnesium) salts of higher alkyl benzene sulphonates and mixtures with olefin sulphonates and higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates.

Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol ; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, the condensate containing from 40 to 80% of polyoxyethylene radicals by weight and having a molecular weight of from 5,000 to 11,000; tertiary amine oxides of structure R₃NO, where one group R is an alkyl group of 8 to 18 carbon atoms and the others are each methyl, ethyl or hydroxyethyl groups, for instance dimethyldodecylamine oxide; tertiary phosphine oxides of structure R₃PO, where one group R is an alkyl group of from 10 to 18 carbon atoms, and the others are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms, for instance dimethyldodecylphosphine oxide; and dialkyl sulphoxides of structure R₂SO where the group R is an alkyl group of from 10 to 18 carbon atoms and the other is methyl or ethyl, for instance ethyltetradecyl sulphoxide; fatty acid alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans .

It is also possible to include cationic, amphoteric, or zwitterionic detergent actives in the compositions according to the invention.

Suitable cationic detergent actives that can be incorporated are alkyl substituted quarternary ammonium halide salts e.g. bis (hydrogenated tallow) dimethylammonium chlorides, cetyltrimethyl ammonium bromide, benzalkonium chlorides and dodecylmethylpolyoxyehtylene ammonium chloride and amine and imidazoline salts for e.g. primary, secondary and tertiary amine hydrochlorides and imidazoline hydrochlorides.

Suitable amphoteric detergent-active compounds that optionally can be employed are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water- solubilizing group, for instance sodium 3-dodecylamino- propionate, sodium 3-dodecylaminopropane sulphonate and sodium N-2-hydroxydodecyl-N-methyltaurate .

Suitable zwitterionic detergent-active compounds that optionally can be employed are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance 3- (N-N-dimethyl-N-hexadecylammonium) propane- 1-sulphonate betaine, 3- (dodecylmethyl sulphonium) propane- 1-sulphonate betaine and 3- (cetylmethylphosphonium) ethane sulphonate betaine .

It is especially preferred for personal wash systems of the invention to include upto 30% other liquid benefit agents such as non-soap surfactants, skin benefit materials such as moisturisers, emollients, sunscreens, anti ageing compounds are incorporated at any step prior to step of milling. Alternatively certain of these benefit agents are introduced as macro domains during plodding.

Builders:

The detergency builders used in the formulation are preferably inorganic and suitable builders include, for example, alkali metal aluminosilicates (zeolites) , alkali metal carbonate for e.g. sodium carbonate, sodium tripolyphosphate (STPP) , tetrasodium pyrophosphate (TSPP) , citrates, sodium nitrilotriacetate (NTA) and combinations of these. Builders are suitably used in an amount ranging from 1 to 30% by wt .

Benefit agents: If the detergent active is soap and compositions are formulated for personal wash other benefit agents may be incorporated. Examples of moisturisers and humectants include polyols, glycerol, cetyl alcohol, carbopol , ethoxylated castor oil, paraffin oils, lanolin and its derivatives. Silicone compounds such as silicone surfactants like DC3225C (Dow Corning) and/or silicone emollients, silicone oil (DC-200 Ex-Dow Corning) may also be included. Sun-screens such as 4-tertiary butyl-4'- methoxy dibenzoylmethane (available under the trade name PARSOL 1789 from Givaudan) and/or 2 -ethyl hexyl methoxy cinnamate (available under the trade name PARSO MCX from Givaudan) or other UV-A and UV-B sun-screens. Water soluble glycols such as propylene glycol , ethylene glycol , glycerol , may be employed at levels upto 10%.

Inorganic particulates :

Inorganic particulate phase is not an essential ingredient of the formulation but may be incorporated especially for hard surface cleaning compositions and for cost effectiveness. Preferably, the particulate phase comprises a particulate structurant and/or abrasive, which is insoluble in water. In the alternative, the abrasive may be soluble and present in such excess to any water present in the composition that the solubility of the abrasive in the aqueous phase is exceeded and consequently solid abrasive exists in the composition. It is particularly preferred that no clay is incorporated in the formulation.

Other additives:

Other additives such as one or more water insoluble particulate materials such as polysaccharides such as starch or modified starches and cellulose may be incorporated. Similarly enzymes & bleaches can be incorporated at levels from 0 - 5%

Minor additives:

Conventional ingredients preferably selected from enzymes, antiredeposition 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%. EXAMPLES ;

The invention will now be demonstrated with the help of typical non-limiting example of the process according to the invention and also with the help of comparative results of the composition prepared by the present invention and beyond the invention.

Different formulations as described in Table 1 were prepared and analysed for hardness, and % moisture.

Process for preparing the detergent bar

Example 1: 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 required sodium carbonate, followed by the addition of 360g (formulation) sodium carbonate. 300 g of (50%) aluminium sulphate and 220 g of (40%) silicate was added to generate aluminosilicate. Other ingredients such as 720 g of STPP builder, approximately 3 kg of fillers (calcite and china clay) , water and minor ingredients were then added. These were thoroughly mixed and plodded in a conventional manner (Example 1) .

Example 2 - Nil Clay Conventional bar

In Example 2, the same procedure was followed as described in Example 1 but the china clay was replaced with calcite. The removal of china clay resulted in poor binding of the dough and hence extra water had to be added. This increased the bar moisture content and the bar softness, as a consequence. Example 3 - Nil Clay with in si tu Generation of Boron-Glycerol Gel

LAS acid was neutralised as described in example 1, following which boron-glycerol gel is generated in the mixer using 3% (180 grams) glycerol and 1.2% (72g) boric acid. All other conventional ingredients and alumino-silicate structuring are then added. Calcite is increased appropriately to compensate for removal of clay.

Example 4 - Nil Clay with in si tu Generation of Boron-Sorbitol Gel

LAS acid was neutralised as described in example 1, following which boron-sorbitol gel is generated in the mixer using 3% (180 grams) sorbitol and 1.2% (72g) boric acid. All other conventional ingredients (other than clay) and alumino-silicate structuring are added. Calcite is increased appropriately to compensate for removal of clay.

Example 5 - Only Boric Acid In Example 5, 4.2% (252 g) boric acid (on total formulation) was added (as a powder) after LAS neutralisation. The resulting nil china clay bars were very soft.

Example 6 - Only Glycerol In Example 5, 4.2% (that is, 252 g) glycerol (on total formulation) was added after LAS acid neutralisation. The resulting nil clay bars were very soft.

Example 7 - Only Sorbitol In Example 5, 4.2% (that is, 252 g) sorbitol (on total formulation) was added after LAS acid neutralisation. The resulting nil clay bars were very soft. Examples 8 and 9

Further, increasing the level of sorbitol-boron complex helps in reduction of the active detergent (examples 1, 8 and 9) . Bars with 10% detergent active (example 9) can be processed satisfactorily as evident from the penetration values.

Bar hardness

Bar hardness for a given moisture level is a direct indicator 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. The higher the penetration, the lower the hardness and the yield stress 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 gm for 20 seconds on top of a flat surface of the bar. The depth of penetration is reported in mm.

Table 1

The data presented in Table 1 show that incorporation of boron- polyol gel helps in bar structuring. In the absence of the boron-polyol gel if clay is removed, the bar become soft and is not processable (example 2) . Moreover, incorporation of only a boron-containing compound or polyol leads to inferior bar structuring (examples 5,6 and 7) and the presence of both (boron-containing compound and polyol) leads to bars of acceptable hardness, bar integrity and properties (Examples 3 and 4) .

Further, increasing the level of sorbitol-boron complex helps in reduction of the active detergent (examples 1, 8 and 9) . Bars with 10% detergent active (example 9) and no clay can be processed satisfactorily by this process. However, when the sorbitol-boron complex was not added and the level of the active detergent was reduced to 10 or 15% in the absence of clay the bars were not processable at all.

Claims

1. A process for the preparation of bars not containing any clay, comprising the steps of:

a. reacting the precursor of a detergent active with an alkaline material; b. adding a mixture of at least one polyol and a boron containing compound; c. adding sodium alumino silicate or generating in situ sodium alumino-silicate by allowing a source of monomeric aluminium to condense with silicate anion; d. adding if desired other detergent actives, builders and minor ingredients; and e. converting the product into bars by conventional method,

the ingredients needed in the process being incorporated in such amounts as to provide a bar composition comprising: from 5 to 70% by weight of detergent active; from 0.5 to 30% by weight of boron-polyol gel; from 1 to 15% by weight of aluminosilicate; from 5 to 20% by weight of water; from 0-30% by weight of detergency builder; and from 0 to 60% by weight of inorganic particulates.

2. A process according to claim 1, wherein the polyol comprises more than two hydroxyl groups, selected from the group consisting of glycerol, sorbotol, xylitol, mannitol, monosaccharides, and disaccharides .

3. A process according to claim 1 or claim 2, wherein the boron containing compound is selected from borax, boric acid and mixtures thereof .

4. A process according to any of claims 1-3, wherein the reaction between the boron containing compound and the polyol is effected in the presence of a cross-linking agent.

5. A process according to any of claims 1-4, wherein the mole ratio of the boron containing compound to the polyol is from 0.1 to 15.

6. A process according to any of claims 1-5, wherein the boron- polyol gel is generated after forming of the detergent active.

7. A process according to any of claims 1-6, wherein aluminium sulphate and alkaline sodium silicate are used for generating in situ the alumino silicate.

8. A process according to any of claims 1-7, wherein the aluminosilicate is generated in situ or incorporated after the formation of the boron-polyol gel.