WO2000034430A1

WO2000034430A1 - Detergent bar composition

Info

Publication number: WO2000034430A1
Application number: PCT/EP1999/007494
Authority: WO
Inventors: Vinodkumar Ramniranjan Dhanuka; Satish Kumar Goel
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Ltd.
Priority date: 1998-12-10
Filing date: 1999-11-09
Publication date: 2000-06-15
Also published as: MY133218A; IN192706B; AU1033600A

Abstract

The invention relates to low pH detergent bar composition comprising a non ionic fatty alcohol ethoxylate (3-20 EO) surfactant with excellent cleaning performance. Also described is a method for the cleaning of fabric using said detergent bar composition.

Description

DETERGENT BAR COMPOSITION

The present invention relates to a low pH synergistic detergent bar and more particularly the compositions of the invention are especially, but not exclusively, useful for fabric washing providing for superior cleaning benefits and additional benefits in terms of colour care and mildness to the skin. The present invention also relates to a method for the cleaning of fabric.

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. It is known that maintaining fabrics' visual appearance over time during repeated wear-wash is not achievable. The main contributory factors are high soil loading, soil redeposition, redistribution, colloid instability of deterged soil, role of hardness ions in rinse, drying and wear, environmental factors, photo degradation in sunlight and washing habits.

Commercial hard surface cleaning compositions typically comprise, one or more surfactants and a plurality of abrasives dispersed in. Combinations of these together with electrolytes are generally used to form a suspending system as is well known in the art.

Japanese patent Nos. 60212496 and 60212497 disclosed that a composition comprising of cellulase, acidic compounds (phytic acid) and anionic surfactants (alpha sulpho fatty ester salts etc.) at pH 5.0 in solution gave better detergency when washing dirt-stained socks compared to alkaline detergents. However, it is restricted to use of cellulase and anionic surfactants. JP4306299 (Kao) teaches a tablet type detergent composition based on nonionic surfactants, a crystalline aluminosilicate and a porous oil-absorbing amorphous silica giving alkaline dispersions. The composition has sufficiently high strength for transport.

BR9600063 (Unilever) teaches a non-soap detergent bar containing 10-60% anionic detergent active, 5-60% a detergency builder and over 4% alkoxylated alcohol. The anionic surfactant to alkoxylated alcohol weight ratio is 1-12:1. Other surfactants may be present as required. The bar has improved stability and softness on the skin.

It is thus evident from the above that there is no teaching on the suitability of low pH detergent compositions in fabric washing and in particular directed to avoiding/controlling the deterioration in visual appearance of fabrics over time during repeated wear and wash.

In our copending application No. 334/BOM/97 there is disclosed and claimed a low pH synergistic detergent powder for fabric washing consisting of a surfactant system, a mix of non-ionic surfactants selected from fatty alcohol ethoxylate with Ethylene Oxide (EO) of levels E03 to E016; silica; and builder. The pH of the powder is below 7. The aforesaid copending application therefore relates to fabric cleaning powder with low pH and high non-ionic surfactants .

The applicants have now found that improved detergent bars may be obtained by using the combination of high non-ionic surfactants in low pH system. It is particularly found that the cleaning properties of the bar are significantly enhanced due to the novel combination of high non-ionic in low pH bars.

Thus the present invention relates to a low pH synergistic detergent bar composition of pH 4 to 7.0 comprising :

i. a surfactant system in an amount of 5 to 50% by wt . of the total composition, said surfactant system comprising 40 to 100% by wt . of the surfactant system of at least one non-ionic surfactant selected from fatty alcohol ethoxylate with Ethylene Oxide (EO) of levels E03 to EO20, optionally in combination with an anionic surfactant; ii. from 10 to 70% by wt . of a structurant; iii. from 5 to 35% by wt . of a pH regulating agent, preferably selected from inorganic acids, organic acids, salts thereof and mixtures of such materials.; iv. from 0 to 50% by wt of at least one inorganic salt, preferably selected from sodium sulphate, sodium chloride and sodium carbonate. It should be understood that the pH of the detergent bar composition is defined as the pH of a 1 % solution in water at 25°C.

According to a further aspect of the invention there is provided a process for manufacture of low pH synergistic detergent bar, comprising mixing the various ingredients in a conventional mixer to form a dough, plodding the dough in an extruder and forming the bar through a die in a conventional manner.

The surfactant system is preferably present in an amount of between 15 to 25 % by wt . of the total composition. In accordance with the invention the non-ionic surfactant used in the formulation is preferably selected from fatty alcohol ethoxylates with ethylene oxide levels E0₇ to E0₁₆.

Preferably, the surfactant system can include a co- surfactant such as linear alkyl benzene sulphonate, betaines, sodium lauryl ethoxy sulphate, alpha olefin sulphonate and coco mono ethanol amide and those known to the skilled in the art and generally described in literature, for example in Surface Active Agents and Detergents, Volume II by Schwartz, Perry and Berch (Interscience Publishers, N.Y. 1958).

The structurant is preferably selected from alkali metal silicate, china clay, silica, zeolite and mixtures thereof. The structurant preferably comprises alkalimetal silicate in the amount of 0.5 to 10% by wt . of the total composition, more preferably, from 1 to 2.5% by wt . One especially preferred alkali metal silicate is aluminosilicate . The structurant preferably comprises china clay in an amount of 5 to 60% by wt . of the total composition, more preferably 25 to 45% by wt . In many cases it will be very usefull if the structurant comprises silica in an amount of 0 to 15% by wt . of the total composition and/or zeolite in an amount of 0 to 15% by wt . of the total composition. More preferably, the structurant comprises silica in an amount of 4 to 8% by wt . of the total composition and/or zeolite in an amount of 4 to 8% by wt . of the total composition.

A pH regulating agent can be added to provide the necessary pH control. The pH regulating agent is present in the bar preferably in an amount of between 10 to 20% by wt . Suitable regulating agents are preferably selected from inorganic acids, organic acids, salts thereof and mixtures of such materials. Preferred inorganic agents include sodium and potassium bicarbonates, acid pyrophosphates, acid orthophosphates, metaphosphates, bisulfates and boric acid. Preferred organic agents include fatty acids, lactic acid, glycolic acid and other derivatives thereof; succinic acid, malonic acid (ethylenedioxy) diacetic acid, maleic acid, diglycollic acid, tartaric acid, tartronic acid and fumaric acid, citric acid, aconitic acid, citraconic acid, carboxymet yloxy succinic acid, lactoxysuccinic acid, and 2-oxa-l-, 1, 3-propane tetracarboxylic acid and 1,1,2,3- propane tetracarboxylic acid; cyclopentane-cis, cis- tetracarboxylic acid, tetracarboxylic acid, 2,5- tetrahydrofuran-cis-cis-dicarboxylic acid, 1,2,3,4,5,6- hexane-hexacarboxylic acid mellitic acid, pyromellitic acid and the phthalic acid derivatives; ethylene diamine tetra (methylene-phosphoric acid) , diethylene triamine penta (methylenephosphonic acid) and the acid salts of the above organic acids. Of the above, the more preferred organic acids are citric acid, fatty acids and the two phosphonic acids .

According to the invention the detergent bar further comprises at least one inorganic salt selected from sodium sulphate, sodium chloride, sodium carbonate and like being present in the bar in amounts of between 0 to 50% by wt . and preferably 4 to 10% by wt .

The low pH synergistic bar of the invention can also include an enzyme, a bleach and other minor ingredients. Preferred enzymes comprise lipase (e.g. Lipolase™) , protease (e.g. Savinase™) , amylase and cellulases (e.g. Clazinase™) . Preferred bleaches comprise sodium sulphite, sodium dithionite, sodium perborate, sodium persulphate, peroxide and the like. Minor ingredients comprise perfume, anti redeposition agents, soil release agents, fluorescers and the like.

The present invention also encompasses a method for the cleaning of fabric comprising the step of contacting fabric with a detergent bar composition according the invention. In accordance with yet another aspect of the invention the same provides for optimal use of selected sequestrants and enzymes in the low pH detergent formulation of the invention for fabric washing incorporating said non-ionic mix surfactant system.

All percentages, unless indicated otherwise, are intended to be percentages by weight of the total composition.

All numerical ranges in this specification and claims are intended to be modified by the term about.

Finally, where the term comprising is used in the specification or claims, it is not intended to exclude any terms, steps or features not specifically recited.

The following examples are intended to further illustrate the invention and are not intended to limit the invention in any way:

EXAMPLES :

Detergent bars (Examples I to X) containing LAS, nonionic Surfactant (Cι₂EOι₄), china clay, aluminium sulphate, sodium tri poly phosphate (STPP) , sodium hexa eta phosphate (SHMP) , alkali silicate and other compounds were manufactured in a conventional plant consisting of a sigma mixer, and plodder.

Processing of bars : The various ingredients of the formulation in the levels indicated in Tables I and II were mixed in a particular sequence in a sigma mixer to prepare a dough of appropriate consistency. This was then plodded in an extruder and given the desired shape through a die. In case of bars containing only nonionics, the process starts with the addition of china clay to the mixer followed by the surfactant. In case of mixed surfactant bars, the nonionic is first mixed in the LAS acid slurry which is neutralised using soda ash before adding the other ingredients to the sigma mixer and then the process follows the same way as the bars with only nonionics. Appropriate amount of time is allowed at various stages of the processing (mixing) for neutralisation and/or structuring to take place.

For the purpose of the cleaning efficiency, the bars according to the invention and bars out of the invention were tested using soiling and washing protocols described hereinafter.

Soiling and washing protocols :

Cotton fabric swatches were desized by washing in a detergent solution in the washing machine at 90°C for 1 hour. The swatches were rinsed thrice and dried. A standard composite soil comprising of a mixture of synthetic sebum and particulates was loaded on swatches using a spray method such that the reflectance of the fabric reached 55 ± units at 460 nm. These swatches were soaked in water and then the bar (Examples I to X) was rubbed (-18 rubs) on the fabric and allowed to soak for 10 minutes, followed by scrubbing with a plastic brush (~ 25 rubs) . The swatches were rinsed well with water.

Measurement of Detergency :

The initial reflectance of the soiled fabric was measured at 460 nm. using a Milton Roy Match Scan II. The fabric was washed following the protocol described above and the reflectance of the washed fabric was measured. The difference in the reflectance of the fabric before and after wash represented as ΔR460* gives the detergency benefit .

Table 1

Table 2

ΔR460* = R460* (washed) - R460* (soiled)

The ΔR460* data presented in Fig 1 and 2 show that the bars of Example I which combines the concepts of low pH and high non-ionic surfactant is better than the bar of Example II which has low pH but no non-ionic surfactant, and also better than the bar of Example III which has high level of non-ionic surfactant but not low pH . Likewise, the bars of Examples VI to X also demonstrate that pH of below 7 coupled with high non-ionic surfactant demonstrate superior cleaning properties. Since the comparison is made on equal active surfactant basis, this clearly establishes the synergistic detergency effects of low pH and high nonionic in detergent bars .

Claims

WE CLAIM :

1. A low pH synergistic detergent bar composition of pH 4 to 7.0 comprising:

i. a surfactant system in an amount of 5 to 50% by wt . of the total composition, said surfactant system comprising 40 to 100% by wt . of the surfactant system of at least one non-ionic surfactant selected from fatty alcohol ethoxylate with Ethylene Oxide (EO) of levels E03 to EO20, optionally in combination with an anionic surfactant; ii. from 10 to 70% by wt . of a structurant; iii. from 5 to 35% by wt . of a pH regulating agent, preferably selected from inorganic acids, organic acids, salts thereof and mixtures of such materials.; iv. from 0 to 50% by wt of at least one inorganic salt, preferably selected from sodium sulphate, sodium chloride and sodium carbonate.

2. A composition according claim 1 wherein the surfactant system is present in an amount of 15 to 25% by wt . of the total composition.

3. A composition according claims 1 or 2 characterised in that the non-ionic surfactant is selected from fatty alcohol ethoxylates with ethylene oxide levels E07 to E016.

. A composition according claims 1 to 3 characterised in that said surfactant system further comprises a co- surfactant preferably selected from the group consisting of linear alkyl benzene sulphonate, betaines, sodium lauryl ethoxy sulphate, alpha olefin sulphonate and coco mono ethanol amide.

5. A composition according any preceding claim characterised in that the structurant is selected from alkali metal silicate, china clay, silica, zeolite and mixtures thereof.

6. A composition according any preceding claim characterised in that the structurant comprises an alkalimetal silicate in the amount of 0.5 to 10% by wt . of the total composition.

7. A composition according to any preceding claim characterised in that said composition comprises from 10 to 20% by wt . of a pH regulating agent, preferably the pH regulating agent is selected from the group consisting of sodium and potassium bicarbonates, acid pyrophosphates, acid orthophosphates, metaphosphates, bisulfates and boric acid.

8. A composition according to any preceding claim characterised in that the composition further comprises at least one substance selected from the group consisting of sequestrant, enzyme and perfume.

9. A method for the cleaning of fabric comprising the step of contacting fabric with a detergent bar composition according to any preceding claim.

10. A low pH synergistic detergent bar of pH 4 to 7.0 substantially as hereindescribed and illustrated with reference to the accompanying examples .