WO2001042413A1

WO2001042413A1 - Detergent bar composition and process for its manufacture

Info

Publication number: WO2001042413A1
Application number: PCT/EP2000/011120
Authority: WO
Inventors: Vidur Behal; Satishkumar Gopinat Nair; Winston Anthony Pereira; Meena Rajan; Raveendranathan Vadumkootil
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Ltd
Priority date: 1999-12-08
Filing date: 2000-11-09
Publication date: 2001-06-14
Also published as: BR0016211A; AU2157101A

Abstract

A detergent bar composition comprising from 10 to 60 % by weight of detergent active; from 0.5 to 40 % by weight of colloidal aluminium hydroxide-phosphate and/or aluminium hydroxide-sulphate complex (Al-complex); from 0-30 % by weight of detergent builder; from 0-60 % by weight of inorganic particulate material; from 8 to 35 % by weight of water and optionally other liquid benefit agents; and the balance optionally being other minor additives.

Description

DETERGENT BAR COMPOSITION AND PROCESS FOR ITS MANUFACTURE

Technical Field

The invention relates to detergent bars for fabric washing or hard surface cleaning. This invention particulary relates to an improved process for preparing a low density detergent bar comprising high levels of water and with good physical and sensorial attributes.

Background to the Invention

Fabric washing compositions contain, as an essential ingredient, a surfactant system whose role is to assist in removal of soil from the fabric and its suspension in the wash liquor. 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 water content in the detergent bars is generally maintained around 6%. The binders and fillers used in non-soap detergent (NSD) 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 NSD 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 NSD 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.

IN-A- 177828 discloses a process wherein by providing a balanced combination of aluminium hydroxide and total fatty matter (TFM) it is possible to prepare a low TFM bar having high water content but with satisfactory hardness. The patent teaches the generation of colloidal alumina hydrate in-situ by a reaction of fatty acid or an acid precursor of an active detergent with an aluminium containing alkaline material such as sodium aluminate to form bars which are obtained by plodding.

Indian Patent Application 8107Bom/98 discloses a process of preparing a low TFM a reaction of fatty acid with an aluminium containing alkaline material such as sodium aluminate solution that specifically has a solid content of 20 to 55% wherein the alumina (Al₂0₃) to sodium oxide (Na₂0) is in a ratio of 0.5 to 1.55 by weight gives superior bar properties. These bars have improved hardness and smoother feel. This reaction can take place in a broader temperature range of 40 to 95°C.

It has now been found that in situ generation of aluminium hydroxide- phosphate/sulphate complex by a reaction of an acid precursor of an active detergent in presence of phosphoric or sulphuric acid with an aluminium containing alkaline material such as sodium aluminate that specifically has a solid content of 40 to 96% wherein the alumina (Al₂0₃) to sodium oxide (Na 0) is in a ratio of 0.8 to 1.64 by weight gives superior bar properties. These bars will have significantly lower density and improved physical and sensory properties such as bar hardness, colour, feel, mush etc. By the above process 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.

Definition of the Invention

According to a first aspect of the invention there is provided detergent bar composition comprising

from 10 to 60% by weight of detergent active; from 0.5 to 40% by weight of colloidal aluminium hydroxide-phosphate and/or aluminium hydroxide-sulphate complex (Al-complex); from 0-30% by weight of detergent builder; from 0-60% by weight of inorganic particulate material; from 8 to 35% by weight of water and optionally other liquid benefit agents; and the balance optionally being other minor additives.

A second aspect of the present invention provides an improved process for preparing a detergent bar comprising a composition according to the first aspect of the invention, the process comprising the steps of:

a. reacting a mixture of one or more precursor of detergent active such as herein described and phosphoric and/or sulphuric acid with an aluminium containing alkaline material such as sodium aluminate with a solid content of 40 to 96% wherein the Al₂0₃ to Na₂0 is in a ratio of 0.8 to 1.64 by weight to obtain a mixture of aluminium hydroxide-phosphate and/or aluminium hydroxide-sulphate complex and detergent active at a temperature between 65°C to 95°C; b. Admixing with the product of step a, if desired, any other components; and c. converting the composition so formed into bars.

According to a third aspect of the invention there is provided detergent bar composition comprising: from 10 to 60% by weight anionic non-soap detergent active; from 0.5 to 40% by weight of colloidal aluminium hydroxide-phosphate and/or aluminium hydroxide-sulphate complex (Al-complex); from 0-30% detergent builder; from 0-50% inorganic particulate material; from 8 to 35% by weight of water and optionally other liquid benefit agents; and the balance optionally being other minor additives

According to a fourth aspect the invention provides an improved process for preparing a detergent bar composition according to the third aspect of the present invention, wherein in step a, wherein the Al₂0₃ to Na₂0 is in a ratio of 1.0 to 1.5 by weight, optionally, a predetermined amount of water is admixed with the Al-complex and the other components in step c are selected from detergent actives, alkaline materials, inorganic particulates, builders and minor additives, and mixtures thereof. Detailed Description of the Invention

The precursor of the detergent active and the acid may be partially or fully reacted with sodium aluminate to generate the Al-complex and detergent active. When the reaction is carried out partially the remaining acid is neutralised with any other alkali.

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 the tangential design.

Detergent active

The detergent active used in the process 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 the molecular structure an alkyi 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, alpha olefin sulphonates and their mixtures with higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates.

Other anionic detergent actives are soaps and when present may be upto 10% by weight of the composition. 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 preferred ones are Cι₂-C₁₈ fatty acid soaps.

Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophiHc in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophiHc 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 hydrophiHc 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 methyltetradecyl 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) dimehtylammonium 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.

Colloidal aluminium hydroxide phosphate or aluminium hydroxide- sulphate complex:

For the purpose of the invention the Colloidal aluminium hydroxide phosphate or aluminium hydroxide-sulphate complex is prepared by reacting aluminium containing alkaline material such as sodium aluminate with a solid content of 40 to 96% wherein the Al₂0₃ to Na₂0 is in a ratio of 0.8 to 1.64 and preferably 1.0 to 1.5 and a temperature range of 65 to 95°C with phosphoric acid or sulphuric acid. If sodium aluminate is used as an aqueous solution, then the solid content is in the range 40 to 55% by wt. and when it is a solid it is with a moisture content of 4 to 35% by wt. The commercial phosphoric acid or sulphuric acid can be employed in the reaction and the wt. ratio of Al₂0₃ to phosphoric acid is preferably 0.4 to 1.56 and the wt. ratio of Al₂0₃ to sulphuric acid is 0.5 to 1.1. Aluminium containing alkaline material

For the purpose of the invention the alkaline material used is either sodium aluminate solution with a solid content of 40 to 55% or in the solid form where the moisture content of the solid varies between 4-35% wherein the Al₂0₃ to Na₂0 is in a ratio of 0.8 to 1.64.

Phosphoric or sulphuric acid:

The commercially available phosphoric or sulphuric acid can be employed in the reaction and the weight ratio of Al₂0₃ to phosphoric acid is preferably 0.4 to 1.56, and the weight ratio of Al₂0₃ to sulphuric acid is preferably 0.5 to 1.1.

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 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.

Inorganic particulates

Inorganic particulate phase is an essential ingredient of the formulation and especially of many hard surface cleaning compositions. 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.

Suitable inorganic particulates can be selected from, particulate zeolites, 5 calcites, dolomites, feldspars, silicas, silicates, other carbonates, bicarbonates, borates, sulphates and polymeric materials such as polyethylene.

The most preferred inorganic particulates are calcium carbonate (as Calcite), mixtures of calcium and magnesium carbonates (as dolomite), sodium 10 hydrogen carbonate, sodium/potassium sulphate, sodium/potassium chloride, zeolite, feldspars, talc, koalin, silica and soapstone.

Calcite, talc, kaolin, feldspar and dolomite and mixtures thereof are particularly preferred due to their low cost and colour.

15

The inorganic particulate structurants such as alumino silicate may be generated in situ using aluminium sulphate and sodium silicate in the formulation. It is also possible to incorporate readily available sodium alumino- silicate, other structuring and hardening materials such as

20 aluminium/magnesium sulphate, aluminium hydrate, alkaline silicate and calcium hydroxide.

Minor additives

25 The minor and 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, polysaccharides such as starch or modified starches and celluloses may optionally be incorporated up to

30 10 wt%. Processing

The composition components may be blended 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, multiwiping overlap, single curve or double arm. The double arm kneading mixers can be of overlapping or the tangential design.

Alternatively, the blending 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 process.

The processed components may be formed into bars by any known process.

Detergent bars have conventionally been performed by one of two methods. The first of these is the so-called extrusion process in which a pre-formed composition comprising all components of the bar is typically plodded, i.e. extruded through an eye-plate, to form a continuous "rod", and the continuous rod cut into smaller pieces of predetermined length, commonly referred to as "billets". These billets are fed through a stamper, or alternatively, and especially in the production of low cost NSD bars, are merely given an imprint on one or more surfaces. Such embossing or imprinting may be achieved using a die of the same dimensions as the bar surface which is hit with force, such as a mallet, or a die in the shape of a roller.

Stamping of detergent bars from an extruded billet, using a die, is carried out to give the bars a reproducible shape, smooth surface and/or to imprint a design such as a logo, trade mark or similar onto at least part of a surface of the bar. Stampers typically have a die formed in two halves each with a surface that contacts the billet during the stamping operation. These surfaces are adapted to close to a pre-set separation distance, thereby compressing the billet between the die halves to give the bar its final shape and appearance, and then separate. Excess composition is squeezed out from the die halves as they close. This is commonly referred to as the "flash". The flash is then separated from the soap bar by transferring the bar through holes in a "deflashing plate". Flash can account for up to 40% of the billet material and is generally recycled back into the milling step.

Illustrations of a few non-limiting examples are provided herein showing comparative results of the composition prepared by the present invention and beyond the invention.

EXAMPLES: Illustrations of a few non-limiting examples are provided herein showing comparative results of the composition prepared by the conventional process and that according to the present invention. The composition details and their results are described in Table 1.

Conventional process for preparing a Non-soap detergent bar

Sodium carbonate was charged into a sigma mixer and sulphonic acid and water was added into the mixer. The mass was mixed for about 2 minutes and then the other conventional ingredients such as colour, china clay, builders, fillers and structurants were added in a predetermined sequence and the dough was plodded. The different levels of water in the composition was altered as shown in Table 1 in Examples 1 and 2. Example 3 corresponds to Example 1 , except that the amount of l_AS detergent active material is less. Process according to the invention

Example 4:

Sodium aluminate solution with a solid content of 44% was charged into the sigma mixer and sulphuric acid was added slowly onto it. This was followed by the addition of colour and required amount of water and then phosphoric acid was added slowly into the mixer and mixed for 2 minutes. Then other ingredients as indicated in Table 1 were added and the dough was plodded.

Example 5:

Sodium aluminate solid with a water content of 35% was charged into the sigma mixer and sulphuric acid was added slowly onto it. This was followed by the addition of colour and required amount of water and then sulphuric acid was added slowly into the mixer and mixed for 2 minutes. Then other ingredients as indicated in Table 1 were added and the dough was plodded.

Example 6:

Sodium aluminate solid with a water content of 35% was charged into the sigma mixer and sulphuric acid was added slowly onto it. This was followed by the addition of colour and required amount of water and then phosphoric acid was added slowly into the mixer and mixed for 2 minutes. Then other ingredients as indicated in Table 1 were added and the dough was plodded. The bars were tested following the procedure described below.

Water retention

The bars were weighed and stored under ambient conditions (~ 30°C), ~ 40°C and 85% relative humidity and ~ 40°C and 40% relative humidity for 90 days. The weight of the bars were taken periodically upto 90 days. The data is presented as % moisture loss from the bar at the end of 90 days. Penetration Value (PV)

Penetration value indicating the hardness of the bar was measured using a cone penetrometer the details of a typical instrument and the method of measurement is given below.

Cone type Penetrometer

MANUFACTURER: Adair Dutt & Company, Bombay. RANGE OF MEASUREMENT: 0 - 40 mm

RANGE OF VERIFICATION: 20 in steps of 5

Procedure of Measurement: Let the entire mass (comprises of penetrometer needle and standard weight) which just rests on the test sample, drop freely and thus penetrate the test mass to a specific distance for a specified period of time and read of this distance as 1/10^th of mm.. Take the average after repeating the exercise for at least 3 times.

Density of the bar

The density of the bar is measured by the standard method and calculated using the formula

Density (grams/cm³) = Weight of bar (grams) Volume in cm³

Mush:

Refers to the paste like layer formed on the bar surface upon contact with water and is estimated by measuring the amount of bar loss/unit area. Lather :

Refers to foam generated during wash by which the consumer controls the product dosage.

Table 1

Data presented in Table 1 show that it is not possible to make NSD bars with high moisture content using the conventional formulation. With the Al-complex structuring route it has been possible to make lower density NSD bars at equivalent active levels with nil mineral fillers and higher moisture contents. These bars have higher water holding capacity as measured at different temperatures and humidity. Negative values of moisture loss % indicate that the bar is able to absorb moisture from the atmosphere and still retain its structure and good physical properties. At high temperature and low humidity the values are positive indicating moisture loss and this loss is significantly lower in the bars according to the invention as compared to the control.

These bars have equal bar hardness, detergency and lather as conventional bars. The sensorial attributes of the bar like feel and colour and the in use attributes are significantly better than conventional bars.

It has also been possible to eliminate minerals from the composition and thus reduce variability in quality of the bar and improve sensory properties such as colour, bar feel and reduce mush and sog. The bar density is also reduced thus enabling the production of larger bars that are more convenient to use.

Claims

1. A detergent composition comprising

2. A composition according to claim 1 , comprising from 0-50% of the inorganic particulate material.

3. A bar formed of a composition according to either preceding claim.

4. A process for preparing a detergent bar comprising a composition according to claim 1 or claim 2, the process comprising the steps of:

a. reacting a mixture of one or more precursor of detergent active such as herein described and phosphoric and/or sulphuric acid with an aluminium containing alkaline material such as sodium aluminate with a solid content of 40 to 96% wherein the Al₂0₃ to Na₂0 is in a ratio of 0.8 to 1.64 by weight to obtain a mixture of aluminium hydroxide-phosphate and/or aluminium hydroxide-sulphate complex and detergent active at a temperature between 65°C to 95°C; b admixing with the product of step a, if desired, any other components; and c converting the composition so formed into bars.

5. A process according to claim 4 for preparing a bar with a composition according to claim 1 or claim 2, wherein in step a, wherein the Al₂0₃ to Na₂0 is in a ratio of 1.0 to 1.5 by weight, optionally, a predetermined amount of water is admixed with the Al-complex and the other components in step c are selected from detergent actives, alkaline materials, inorganic particulates, builders and minor additives, and mixtures thereof.