EP2598620B1

EP2598620B1 - Detergent composition

Info

Publication number: EP2598620B1
Application number: EP11727452.2A
Authority: EP
Inventors: Richa Sureshchand Goyal; Sujitkumar Suresh Hibare
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2010-07-27
Filing date: 2011-06-24
Publication date: 2014-10-22
Anticipated expiration: 2031-06-24
Also published as: CN103003404A; MX2013001062A; ES2528099T3; WO2012013430A1; EP2598620A1; AU2011285135B2; AU2011285135A1; BR112013001472A2; ZA201300074B

Description

Field of the Invention

The present invention is in the field of detergent powders. The invention particularly relates to detergent granules exhibiting improved dissolution behaviour for faster release of active to a wash liquor.

Background of the invention

Present day laundry products generally contain granules comprising surfactants and optionally other ingredients.
Granules are typically more stable on storage and are easier to handle than conventional powders. In addition, granulation helps in improving the flow characteristics of the primary particulate material. Materials that are hygroscopic in nature have a tendency to cake very easily when stored in powder form. This caking tendency of hygroscopic materials can be reduced to a great extent by granulation. Granules also being denser occupy less space and hence are easy to handle and transport. Such detergent granules have been used in laundry product for several years.
WO 98/04672 discloses a process for preparing a detergent granule for laundry and dish washing detergent products. WO 98/04672 further discloses that a particulate base comprising surfactant and an acid source, in combination with a separate alkalinity source in the composition provides solubility/dispersibility of the composition; in particular it discloses a liquid composition comprising a mixture of surfactant as NaLAS, SLES and a carboxylic acid. However, we have found that the dissolution speed of these granules is fairly poor.
EP 1967512 discloses a process for preparing magnesium salt of linear alkylbenzene sulphonic acid in solid form at high concentration levels, which solid has high rate of dissolution.
Similarly, JP 2005 171203 discloses a method for the manufacture of a detergent particle having good solubility and free fluidity, prepared by mixing an anionic surfactant with a fatty acid in a melted state together with a powdery detergent material. Spraying relatively low amounts of molten fatty acid sprayed on a base powder bed is likely to result in non- homogeneously mixed material, and the objective of getting a homogeneous mixture of other detergent ingredients with fatty acid is likely not to be achieved.
A detergent particle that provides further improved dissolution, even after storage, remains to be desired. This applies not only to detergent powder composition, but also to compositions in tablet form.
It is therefore an object of the present invention to provide a detergent composition having enhanced dissolution properties.
Surprisingly it has been found that a granule comprising a mixture of a magnesium salt of linear alkylbenzene sulphonic acid (Mg(LAS)₂) and a fatty acid when used in detergent powders provides improved dissolution and this better dissolution is maintained even after storage.

Summary of the invention

Accordingly the present invention provides a detergent granule comprising 60-90% by weight of a magnesium salt of linear alkylbenzene sulphonic acid Mg(LAS)₂; 2-20% by weight of a fatty acid; and 2-20% by weight of water.
In a second aspect the invention provides a detergent composition comprising 5-50% by weight of the granule according to any one of claims 1 to 4; 10-60% by weight of a builder; 0-15% by weight of a seed material; and 2 - 30 % by weight of electrolyte material.
In a third aspect the invention provides the use of granule according to anyone of claims 1 to 4 for providing faster dissolution of surfactant material in wash liquor.
By granule is meant an aggregate or multi-particle entity formed by making primary particles adhere together by means of a binder. Granulation typically commences after initial dry mixing of necessary powdered ingredients so that a uniform distribution of each ingredient through the mix is achieved.
By dissolution is meant disintegration of the aggregate/granule into primary particles to increase the leaching which will result into more material available in solution in less time.
By detergent powder is meant a conventional type of detergent powder which is granulated to achieve desired flow characteristics and generally contains surfactant or surfactant mixture, builders, electrolytes, fillers etc. One or more of these ingredients are added in liquid form to achieve the granular product.
These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detail description of the invention

Accordingly the invention provides a detergent granule comprising a magnesium salt of linear alkylbenzene sulphonic acid (Mg(LAS)₂), a fatty acid, and water; and a detergent composition comprising the granule, builder and electrolyte.

Granule

The granule according to the invention comprises a magnesium salt of linear alkylbenzene sulphonic acid (Mg(LAS)₂), a fatty acid, and water.
The granule preferably has a weight average particle size of between 0.5 and 5 mm, more preferably between 1 and 2 mm.
It is preferred that at least 50% of the particles have a size that is within 50% from the average (in other words, not more than 50% larger or 50% smaller than the average). Even more preferably, at least 60%, still more preferably at least 70%, even more preferably at least 80% or even at least 90% of the particles have a size that is within 50% from the average (in other word, not more than 50% larger or smaller than the average).
It is even more preferred that the particles are within 40%, still more preferably within 30% of the average particle size.

Mg(LAS) ₂ .

The magnesium salt of linear alkylbenzene sulphonic acid is preferably a magnesium salt of C8-C16 linear alkyl benzene sulphonic acid, more preferably the magnesium salt of linear dodecylbenzene sulphonic acid.
The granule comprises between 60 and 90% of the Mg(LAS)₂. Preferably the composition comprises at least 65%, still more preferably at least 70% of the Mg(LAS)₂, but preferably less than 85% or even less than 80% of the Mg(LAS)₂ material.
The Mg(LAS)₂ may be used in pure form, but generally includes some excess of magnesium carbonate (MgCO₃) used for converting linear alkylbenzene sulphonic acid in to the magnesium salt form. The amount of excess MgCO₃ is typically less than 20%, preferably less than 10%, more preferably less than 5%, even more preferably less than 2%, still more preferably less than 1%, or even 0%by weight of the Mg(LAS)₂ material. Magnesium is a hardness ion and any excess of magnesium in the wash liquor is preferably avoided.

Fatty acid

The fatty acid is preferably selected from C8 to C18 carbon chain length. The most preferred fatty acid is/are having carbon chain length of C12 to C14. Examples of such suitable fatty acids are lauric acid, myristic acid or mixtures there of.
For the avoidance of doubt by fatty acid is meant that the material is predominantly in the acid form and not in the soap form. More preferably less than 10%, still more preferably less than 5%, even more preferably lass than 1 % or even 0% of the fatty acid material is the soap form.
The granule comprises between 2 and 20% of the fatty acid. Preferably the composition comprises at least 4%, still more preferably at least 6% of the fatty acid, but preferably less than 15% or even less than 10% of the fatty acid.

Water

Some water is required to formulate the granule.
The granule typically comprises between 2 and 20% of water. Preferably the composition comprises at least 4%, still more preferably at least 6% of water, but preferably less than 15% or even less than 10% of water.

Detergent composition.

The detergent composition preferably comprises between 5 and 50 of the granule according to the invention, preferably at least 10%, more preferably at least 15%, or even at least 20%, but typically less than 40%.

Builder

The detergent composition further comprises a builder for removing hardness ions from the wash liquor. The builder may be selected from any common builder material, including carbonate builders, such as soda (Na₂CO₃), bicarbonate, phosphates, such as STPP, alkaline sodium silicate, sodium metasilicate and zeolites.
The builder is present in the detergent composition in a concentration of between 10 and 60%, depending on water hardness and the type of builder. Preferably the composition comprises at least 20% of builder or even at least 25%, but generally less than 50% by weight of the detergent composition.
It is essential that at least part of the builder in the detergent composition is alkaline builder material, including, but not limited to carbonate builders, such as soda (Na₂CO₃) and bicarbonate, alkaline sodium silicate and sodium metasilicate.
For the best results, the ratio of alkaline builder to fatty acid in the composition is at least 1, preferably at least 2, more preferably at least 5.

Seed material

Some builders, such as soda, perform better in the presence of a seed material.
Soda is thought to remove calcium ions from solution by precipitation as calcium carbonate. This precipitation kinetics can be either enhanced by increasing the concentration of soda in solution or by using a seed that acts as a nucleus for the precipitating species. It is always preferred to use fine powder of the seen material to increase the available surface area and reduce the amount of seed required for effective building of calcium ions.
Common seed materials, suitable for use in the granule of the invention, include dolomite and calcite; calcite being the most preferred.
The seed material is present in a concentration of between 0 and 15% by weight, preferably at least 1%, more preferably at least 2% or even at least 5%, but generally less than 10% by weight of the detergent composition.

Electrolyte

The detergent composition according to the invention optionally comprises of between 2 and 30% by weight of an electrolyte, preferably at least 5%, but typically less than 20%.
The electrolyte may be preferably selected from sodium chloride, sodium sulphate; chloride being the most preferred. The electrolyte may also act as filler material. This electrolyte excludes the builder material.

Optional ingredients

The detergent composition may further comprise fluorescers, shading dyes, anti-microbial agents, anti-redeposition agents, dye transfer inhibitors, bleaching agents, perfume and/or enzyme granules.

Washing process

The detergent composition is suitable for use in conventional household washing processes.
It is preferred that the total dose of detergent composition, including the granule to a washing machine is between about 25 and 150 g of detergent per wash in a standard 60 L water intake top load washing machine, preferably between 70 and 125 g per wash, more preferably between 80 and 100 g per wash.
For front load washing machines and for hand wash processes, both using approximately 15 L of water intake is between about 25 and 150 g of detergent per wash, preferably the detergent product comprising the builder is dosed in an amount of between 30 and 100 g, more preferably between 50 and 90 g per wash, still more preferably between 60 and 80 g per wash.

Detergent format

The detergent product comprising the granule according to the invention may be in the form of a powder, a tablet or anything in between, such as washing pearls.
In any of the mentioned formats the incorporation of the granule according to the invention, comprising Mg(LAS)₂ surfactant and fatty acid provides faster dissolution of the active into the wash liquor.

Examples

The invention will now be illustrated by means of the following non-limiting examples.

Example 1: Preparing the granule according to the invention.

500 g of pre-prepared Mg(LAS)₂ powder (having an average particle size of 10 micrometer and containing 85% Mg(LAS)₂, the remaining 15% being water and MgCO₃ at about 7.5% each) was loaded in a mixing device (ex Sigma granulator), and mixed with 15 g Lauric acid powder (s.d. fine chemicals Mumbai, 99% pure, average particle size of 50 micrometer) for 2 minutes. 30 g of water was added and mixed for another 2 minutes.
The granules were collected and sieved, wherein the fraction remaining on a 1 mm sieve, but passing through a 2 mm sieve was collected.
Identical granules were prepared without fatty acid addition for the comparative examples.

Example 2: Dissolution test

The granules according to example 1 were used. A detergent composition containing 1.5 g/L of the granule and 1.5 g/L soda (Na₂CO₃) was added water of 25°C in a 500 ml beaker, without stirring. Samples were taken at 5, 10 and 15 minutes.
The surfactant concentration was determined by Hyamine titration method, as commonly used in the art. The dissolution of surfactant in % by weight is given in the table below.

Dissolution results

	Experimental	Comparative
Time (min)	% Dissolution (by wt)	% Dissolution (by wt)
5	13.6	26.4
10	56.4	30
15	63.4	57.3

The table above shows that the detergent composition according to the invention reaches a high surfactant concentration in the water faster and to a higher concentration.

Example 3: Dissolution test of the granule after storage

The granules according to example 1 were used, but now 15 g samples of the granules had been stored for 3 months in sealed air tight plastic pouches at 40°C.
A detergent composition containing 1.5 g/L of the stored granule and 1.5 g/L soda (Na₂CO₃) was added water of 25°C in a 500 ml beaker, without stirring. Samples were taken at 5, 10 and 15 minutes.
The surfactant concentration was determined by Hyamine titration method, as commonly used in the art. The dissolution of surfactant in percentage by weight is given in the table below.

Dissolution results after storage

	Experimental	Comparative
Time (min)	% Dissolution (by wt)	% Dissolution (by wt)
5	12.1	5.2
10	28.8	17.3
15	65.7	38.1

The table above shows that the detergent composition according to the invention reaches a high surfactant concentration in the water faster and to a higher concentration, even after storage.

Claims

A detergent granule comprising
a 60-90% by weight of a magnesium salt of linear alkylbenzene sulphonic
acid Mg(LAS)₂;

b 2-20% by weight of a fatty acid; and

c 2-20% by weight of water.
A granule according to claim 1, wherein the granule has an average particle size between 0.5 and 5 mm.
A granule according to claim 2, wherein at least 50% of the granules have a particle size within 50% of the average.
A granule according to any one of the preceding claims, wherein the granule further comprises a filler material.
A detergent composition comprising
a 5-50% by weight of the granule according to any one of claims 1 to 4;

b 10-60% by weight of a builder, comprising alkaline builder material;

c 0-15% by weight of a seed material; and

d 2 - 30 % by weight of electrolyte material;
wherein the ratio of alkaline builder material to fatty acid in the composition is at least 1.
A composition according to claim 5 wherein the builder is selected from sodium carbonate, sodium bicarbonate, alkaline sodium silicate, sodium metasilicate, sodium tripolyphosphate, zeolite or mixtures thereof.
A composition according to claim 5 or 6 wherein the electrolyte material is selected from sodium chloride, sodium sulphate.
A composition according to claim 5 wherein the seed material is calcite.
A composition according to anyone of claims 5 to 8, wherein the composition is a detergent powder.
A composition according to anyone of claims 5 to 8, wherein the composition is a detergent tablet.
Use of granule according to anyone of claims 1 to 4 for providing faster dissolution of surfactant material in wash liquor.