EP2366006A1

EP2366006A1 - Solid builder composition

Info

Publication number: EP2366006A1
Application number: EP09759729A
Authority: EP
Inventors: Subir K Das; Amitava Pramanik; Arpita Sarkar; Archana Sinha
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2008-12-16
Filing date: 2009-11-24
Publication date: 2011-09-21
Anticipated expiration: 2029-11-24
Also published as: WO2010069718A1; EP2366006B1; CN102257113B; CN102257113A; ZA201103721B

Abstract

The present invention provides a solid builder composition comprising an alkali metal carbonate, an alkali metal silicate, calcium carbonate, and soap, wherein the soap is in form of particles comprising at least 50% by weight soap and wherein at least 80% by weight of the soap particles are retained on sieve of 70 mesh. Said builder composition was found to provide relatively faster building kinetics than known builder compositions of the prior art.

Description

SOLID BUILDER COMPOSITION

TECHNICAL FIELD

The present invention relates to a solid builder composition and a solid detergent composition comprising the same.

BACKGROUND AND PRIOR ART

Water hardness, due to presence of calcium and magnesium ions in water, is known to cause deterioration in cleaning efficacy of fabrics. Use of builders to reduce water hardness and consequently to improve cleaning efficacy is also known. For example, a builder composition comprising sodium carbonate and calcium carbonate is known to be effective in reducing water hardness and improve cleaning efficacy. However, the kinetics of water hardness reduction is relatively slow. Further, the concentration of hardness ions that can be achieved by use of builder compositions of the prior art is relatively high. When such builder compositions are incorporated in detergent compositions, relatively higher concentration of hardness ions coupled with slower kinetics leads to depletion of soluble form of surfactant and consequent reduction in cleaning efficacy.

Present inventors have surprisingly found that a builder composition comprising alkali metal carbonate, calcium carbonate, alkali metal silicate, and soap particles of specific size and specific composition provide relatively faster building kinetics and allow attainment of relatively low hardness ion concentration and that incorporation of the inventive builder composition in a detergent composition provides relatively higher fabric cleaning efficacy in hard water.

EP-A-0234818 describes some examples of a detergent composition comprising non- soap anionic detergent, nonionic detergent, sodium carbonate, calcite, sodium silicate and soap. The slurry comprising all the ingredients except sodium silicate was spray dried to prepare the spray-dried base powder. GB-1424406 describes composition comprising sodium carbonate, soap, calcium carbonate, sodium silicate, and alkyl benzene sulfonate. Soap, alkyl benzene sulfonate, sodium silicate and sodium sulfate were admixed and compacted to form granules.

EP-A-0267042 describes some examples of a detergent composition comprising non- soap anionic detergent, nonionic detergent, sodium carbonate, calcite, sodium silicate and soap. The slurry comprising all the ingredients was spray dried to prepare the base powder.

None of the documents cited above disclose soap particles of specific size or composition.

One of the objects of the present invention is to provide a builder composition that provides relatively fast building kinetics. A further object of the present invention is to provide a builder composition that allows attainment of relatively low hardness ion concentration. Yet another object of the present invention is to provide a detergent composition that provides relatively higher fabric cleaning efficacy in hard water.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a solid builder composition comprising:

(i) an alkali metal carbonate, (ii) an alkali metal silicate, (iii) calcium carbonate, and (iv) soap; characterized in that the soap is in form of particles comprising at least 50% by weight soap and in that at least 80% by weight of the soap particles are retained on sieve of 70 mesh. According to another aspect of the present invention, there is provided a solid detergent composition comprising the builder composition of the first aspect and a non-soap surfactant. DETAILED DESCRIPTION OF THE INVENTION

The builder composition

The builder composition of the present invention is in solid form, and preferably in form of solid particles. The solid particles may be in form of a powder or granules.

Alkali metal carbonate

The alkali metal carbonate is present at a level of 5 to 70%, preferably 10 to 60% and most preferably 15 to 50 % by weight of the builder composition. The % by weight alkali metal carbonate is on anhydrous basis. Alkali metal carbonate is preferably selected from sodium carbonate or potassium carbonate. More preferably, the alkali metal carbonate is sodium carbonate.

Alkali metal silicate The alkali metal silicate is preferably sodium silicate or potassium silicate, more preferably sodium silicate. Sodium silicate is a colorless compound of oxides of sodium and silica. It has a range of chemical formula varying in sodium oxide (Na2θ) and silicon dioxide or silica (Siθ2) contents. It is soluble in water and it is prepared by reacting silica (sand) and sodium carbonate at a high temperature ranging from 1200 to 1400⁰C. Of the various types of sodium silicates available sodium metasilicate is preferred. Both sodium metasilicate pentahydrate as well as sodium metasilicate nonahydrate can be used although sodium metasilicate pentahydrate is preferred as it dissolves faster. The alkali metal silicate is present at a level of 1 to 40%, preferably 2 to 35% and most preferably 5 to 30% by weight of the builder composition. The % by weight alkali metal silicate is on anhydrous basis.

Calcium carbonate

Crystal form of calcium carbonate may be calcite, vaterite or aragonite, with calcite being the most preferable crystal form. Preferably, the calcium carbonate has a surface area greater than 18 m²/g, more preferably greater than 30 m²/g, and most preferably greater than 60 m²/g. Particle size of calcite is preferably from 1 to 100, more preferably from 2 to 50, and most preferably from 2 to10 microns.

Calcium carbonate is present at a level of 3 to 50%, preferably 5 to 40% and most preferably 10 to 30 % by weight of the builder composition.

Soap

It is an essential aspect of the present invention that the soap is in form of particles comprising at least 50% by weight soap and at least 80% by weight of soap particles are retained on sieve of 80 mesh. The soap particles comprise preferably at least 60%, more preferably at least 70% and most preferably at least 80% by weight soap.

At least 80% by weight soap particles are retained on a sieve of 80 mesh, preferably on a sieve of 65 mesh, and more preferably on a sieve of 60 mesh.

Preferably at least 90%, more preferably at least 95% and most preferably substantially all soap particles are retained on a sieve of 80 mesh.

Preferably at least 90% by weight soap particles pass through a sieve of 20 mesh. The soap is preferably selected from an alkali metal soap, an alkaline earth metal soap or ammonium soap. More preferably, the soap is an alkali metal soap. Sodium soap is particularly preferred.

The soap is preferably C8-C24 soap, more preferably C10-C20 soap, and most preferably C12-C18 soap.

The soap may or may not have one or more carbon-carbon double bond or triple bond. The soap may be water soluble or water insoluble. Non-limiting examples soaps that can be used according to the present invention include sodium laurate, sodium caprylate, and sodium myristate, sodium palmitate and sodium stearate.

Soap is present at a level of 1 to 25%, preferably 1 to 20% and most preferably 3 to 15% by weight of the builder composition. Calcium oxide or hydroxide

It is preferred that the builder composition comprises calcium oxide or hydroxide, with calcium hydroxide being particularly preferred. When present, calcium oxide or hydroxide is preferably 0.1 to 15%, more preferably 0.5 to 12% and most preferably 1 to 10 % by weight of the builder composition.

The solid detergent composition

The solid detergent composition comprises the builder composition and a non-soap surfactant. The solid builder composition is preferably 5 to 90%, more preferably 10 to 80% and most preferably 15 to 70 % by weight of the solid detergent composition. The soap is in form of particles comprising at least 50% by weight soap and at least 80% by weight of the soap particles are retained on sieve of 70 mesh.

Non-soap surfactant

The term non-soap surfactant as used herein means any surfactant excluding soap. The non-soap surfactant may be anionic, non-ionic, cationic, zwitterionic or amphoteric. More preferably the non-soap surfactant is an anionic surfactant

Preferably the anionic surfactant is a salt of an acid selected from a group consisting of linear alkyl benzene sulfonic acid, alpha olefin sulfonic acid and primary alkyl sulfuric acid. More preferably, the anionic surfactant is a salt of linear alkyl benzene sulfonic acid.

Preferably the salt is an ammonium salt, an alkali metal salt or an alkaline earth metal salt. More preferably, the salt is an alkaline earth metal salt. It is particularly preferred that the alkaline earth metal is magnesium.

When the non-soap surfactant is a magnesium salt of a linear alkyl benzene sulfonic acid, the non-soap surfactant is in form of particles wherein at least 50% by weight of the non-soap surfactant particles are preferably retained on a sieve of 70 mesh, more preferably retained on 60 mesh, and most preferably retained on a sieve of 50 mesh. Without wishing to be limited by theory, it is believed that combination of specific size of soap particles in the builder composition and the specific size of non-soap surfactant particles provides optimal building and cleaning efficacy.

The non-soap surfactant is preferably present at a level of 5 to 80%, more preferably 10 to 50% and most preferably 15 to 35% by weight of the solid detergent composition.

Process of preparation of the solid builder composition

Soap particles may be prepared by any process. Preferably, a corresponding fatty acid is neutralized to form a soap which is then extruded, and extruded noodles are granulated. Preferably a pan-granulator is used for granulation. The soap granules may be separated according to size by any suitable method, preferably by sieving.

The builder composition may be prepared by a process comprising the step of mixing all the ingredients of the builder composition. Preferably, the builder composition is prepared by a process comprising the steps of:

(1 ) mixing all the ingredients of the builder composition except soap granules, to prepare a premix, and

(2) mixing the soap granules with the premix.

Preferably the step (2) is carried out in a low shear mixer. Examples of low shear mixer include a ribbon mixer or a blender. Preferably the step (2) is not carried out in a sigma mixer.

In low shear mixer, breakage or deformation of soap granules is avoided thus ensuring that the size of soap particles remains unaltered such that at least 80% by weight of the soap particles are retained on a sieve of 70 mesh. Process of preparation of the solid detergent composition

The detergent composition may be prepared by mixing the non-soap detergent with the builder composition.

Preferably the detergent composition comprising an anionic non-soap surfactant is prepared by a process comprising the steps of:

(1 ) neutralizing of an acid selected from a group consisting of linear alkyl benzene sulfonic acid, alpha olefin sulfonic acid and primary alkyl sulfuric acid, (2) mixing the neutralized mass with all the ingredients of the builder composition except soap, and (3) mixing the soap granules with the mix obtained in the step (2)

Preferably the step (3) is carried out in a low shear mixer. Examples of low shear mixer include a ribbon mixer or a blender. Preferably the step (3) is not carried out in a sigma mixer. In low shear mixer, breakage or deformation of soap granules is avoided thus ensuring that the size of soap particles remains unaltered such that at least 80% by weight of the soap particles are retained on a sieve of 70 mesh.

When the non-soap detergent is a magnesium salt of linear alkyl benzene sulfonic acid, the process of preparation of the detergent composition preferably comprises the steps of:

(1 ) neutralizing linear alkyl benzene sulfonic acid with magnesium carbonate,

(2) granulating the magnesium salt of linear alkyl benzene sulfonic acid obtained in the step (1 ), and;

(3) mixing the granules of the magnesium salt of linear alkyl benzene sulfonic acid obtained in the step (2) with the builder composition.

Preferably the step (3) is carried out in the low shear mixer. Preferably the step (3) is not carried out in a sigma mixer. More preferably, the granules of magnesium salt of linear alkyl benzene sulfonic acid obtained in the step (2) are sieved such that at least 50% by weight of the granules of the magnesium salt of linear alkyl benzene sulfonic acid are retained on a sieve of 70 mesh.

EXAMPLES

The invention will now be demonstrated by help of examples. The examples are for illustration purpose only and do not limit the scope of the invention in any manner.

Builder compositions comprising soap were prepared by a process comprising the steps of:

(2) mixing the soap granules with the premix in a ribbon mixer. In case of sodium laurate, soap granules comprised 80% by weight of sodium laurate. In case of sodium palmitate, soap particles comprised 90% by weight soap. Builder composition of Comparative Ex A and Comparative Ex D comprised 48.6% by weight sodium carbonate, 27% by weight calcium carbonate, 24.3% by weight sodium metasilicate. Comparative Ex A and Comparative Ex D did not have soap. Other builder compositions in the table below comprised 45% by weight sodium carbonate, 25% by weight calcium carbonate, 22.5% by weight sodium metasilicate, and 7.5% by weight soap. Calcium carbonate with surface area of 60 m²/g and particle size of 2-10 microns procured from Saurashtra Solid Industries, India was used in all the experiments. The details are tabulated below

Table 1 : Builder compositions

2O 35^" - all soap particles pass through 20 mesh sieve and are retained on 35 mesh sieve.

Further builder compositions

Builder composition of Comparative Ex G comprised 48.5% by weight sodium carbonate, 37.7% by weight calcium carbonate, 9.7% by weight sodium metasilicate (pentahydrate) and, 4.1 % by weight lime (calcium hydroxide). Comparative Ex G did not have soap.

Other builder compositions in the table below comprised 44.9% by weight sodium carbonate, 34.9% by weight calcium carbonate, 9% by weight sodium metasilicate (pentahydrate), 3.7% by weight lime and , and 7.5% by weight soap

Kinetics of building

200 ml_ of hard water of 48 ⁰FH, i.e. having 128 ppm of Ca²⁺ ions and 38.4 ppm of Mg²⁺ ions were taken in a glass beaker. To this solution, various builder compositions were added. After adding the builder composition, the solution was stirred for 45 seconds using a glass rod. A sample was withdrawn with the help of a syringe at pre- determined time periods after the addition of the builders, and filtered through a microfilter into 5 ml_ glass vial. The Ca²⁺ ion and Mg²⁺ ion concentrations were determined by EDTA titration as shown below:

Measurement of total (calcium and magnesium) ion concentration The method involved titration with EDTA (di sodium salt of elthylene diamine tetra acetic acid) using EBT (Ehochrome Black - T) as indicator. About 2 ml_ of the test solution was pipetted out into a 150 ml_ conical flask. The solution was diluted using about 10 ml_ water. To this was added 5 ml_ of ammonia-ammonium chloride pH 10 buffer. About 35 mg of 1 % EBT in potassium nitrate solution was added. A wine red colour was obtained. A standardized EDTA solution was added dropwise from a burette with constant stirring. As more EDTA was added the colour gradually changed from wine red to violet. The end point was identified by a sudden colour change from violet to blue. The total hardness was calculated according to the equation given below.

Total hardness (⁰FH) = volume of EDTA (ml_) * concentration of EDTA (mM) * 10/ volume of test solution (ml_).

Table 3: Building kinetics of builder compositions of Ex No 1 -4 and Comparative Ex No A-C

It can be seen that the builder compositions of the present invention provide relatively fast building kinetics as compared to the builder compositions outside the scope of the present invention.

Table 4 : Building kinetics of builder compositions of Ex No 5-9 and Comparative Ex No D-F

Building kinetics of builder compositions of Ex No 10-14 and Comparative Ex No G-I

The experiments were carried out according to the procedure identical to one described earlier in all respects except that stirring was provided by an overhead stirrer operating at 150 rpm, instead of manual stirring using a glass rod. These experiments operate at high agitation regime simulating condition in washing machines. Table 5 : Building kinetics of builder compositions of Ex No 10-14 and Comparative Ex No G-I

It can be seen that even under simulated machine wash conditions, the builder compositions of the present invention provide relatively fast building kinetics as compared to the builder compositions outside the scope of the present invention. It will be appreciated that the builder compositions of the present invention provide relatively fast building kinetics, achieve attainment of relatively low hardness ion concentration.

Detergent compositions

All the detergent compositions in the following table comprised 19% by weight of LAS (either magnesium or sodium salt), 67% by weight the builder composition, 3% by weight sodium carboxymethyl cellulose, 1 % by weight of sodium sulfite, 4% by weight sodium chloride, 2% by weight moisture and other minor ingredients including perfume and fluorescer.

All the detergent compositions having magnesium salt of LAS were prepared by a process comprising the steps of:

(1 ) neutralizing linear alkyl benzene sulfonic acid with magnesium carbonate, (2) granulating the magnesium salt of linear alkyl benzene sulfonic acid obtained in the step (1 ), and;

(3) mixing the granules of the magnesium salt of linear alkyl benzene sulfonic acid obtained in the step (2) with the builder composition. Prior to step (3), the granules of the magnesium salt of linear alkyl benzene sulfonic acid obtained in the step (2) were sieved such that all the granules are retained on a sieve of mesh 35.

All the detergent compositions having sodium salt of LAS, except the detergent composition of Comparative Example K, were prepared by a process comprising the steps of:

(1 ) neutralizing linear alkyl benzene sulfonic acid with sodium carbonate,

(2) mixing the neutralized mass with all the ingredients of the builder composition except soap in a sigma mixer, and (3) blending the soap granules with the mix obtained in step (2) in a ribbon mixer.

The detergent composition of Comparative Example K was prepared by a process comprising the steps of:

(1 ) neutralizing linear alkyl benzene sulfonic acid with sodium carbonate, (2) mixing the neutralized mass with all the ingredients of the builder composition including soap in a sigma mixer,

(3) granulating the mix obtained in the step (2) in a pan granulator.

The detergent composition was sieved and the fraction retained on mesh 35 was used in the washing experiment.

Fabric cleaning efficacy of detergent compositions in hard water 700 ml_ of water of 48 ⁰FH hardness as prepared earlier was taken in a 1 L container of TERGOTOMETER (Instrument Marketing Services, Inc., NJ, USA). Nine test monitors including three each of WFK 1OD, WFK20D and AS9 (WFK-Testgewebe GmbH) were taken. WFK10D is a cotton fabric having composite soil, WFK20D is a poly-cotton fabric having composite soil and AS9 is a cotton fabric having other variety of composite soil. The experiments were done at a liquor to cloth ratio of 50:1. The solid detergent compositions were added to the water (at 3 g/L) and stirred for 5 minutes at 90 rpm to dissolve the composition. The fabrics were then added and allowed to soak for 15 minutes. Washing was then carried out for 30 minutes with agitation at 90 rpm. The fabrics were then rinsed 3 times for 3 minutes each. The fabrics were then air dried. The reflectance of the fabric before and after washing was measured using a Macbeth color scan spectrophotometer (Color Eye 7000A, Gretag - Macbeth) at a wavelength of 460 nm. The ΔRM60 value is the difference in the reflectance between the washed fabric and the unwashed fabric and is an average value over the three test monitors used.

Details of detergent compositions and cleaning efficacy results are tabulated below Table 6: Details of detergent compositions and cleaning efficacy.

NaLAS - magnesium salt of linear alkyl benzene sulfonic acid MgLAS - magnesium salt of linear alkyl benzene sulfonic acid

It can be seen that the detergent compositions of the present invention provide relatively higher cleaning efficacy on cotton fabric as compared to the detergent compositions that are outside the scope of the present invention. It can also be seen that for cotton fabrics as well as polycotton fabrics, the detergent composition comprising magnesium salt of linear alkyl benzene sulfonic acid provides relatively higher cleaning efficacy as compared to the detergent composition comprising sodium salt of linear alkyl benzene sulfonic acid.

It will be appreciated that the detergent compositions of the present invention provide relatively higher fabric cleaning efficacy in hard water.

Claims

1. A solid builder composition comprising:

(v) 5 to 70% by weight of the builder composition of an alkali metal carbonate, (vi) 1 to 40% by weight of the builder composition of an alkali metal silicate, (vii) 3 to 50 % by weight of the builder composition of calcium carbonate, and

(viii) 1 to 25 % by weight of the builder composition of soap, characterized in that the soap is in form of particles comprising at least 50% by weight soap and in that at least 80% by weight of the soap particles are retained on sieve of 80 mesh.

2. A solid builder composition as claimed in any one of the preceding claims comprising 0.1 to 15 % by weight calcium oxide or calcium hydroxide.

3. A solid detergent composition comprising:

(i) a solid builder composition as claimed in any one of the preceding claims, and (ii) a non-soap surfactant.

4. A solid detergent composition as claimed in claim 7 wherein said builder composition is present at a level of 5 to 90% by weight of the detergent composition.

5. A solid detergent composition as claimed in claims 7 or 8 wherein said non-soap surfactant is present at a level of 5 to 80 % by weight of said detergent composition.

6. A solid detergent composition as claimed in any one of the preceding claims 7-9 wherein said non-soap surfactant is an anionic surfactant.

7. A solid detergent composition as claimed in claim 10 wherein said anionic surfactant is a salt of an acid selected from a group consisting of linear alkyl benzene sulfonic acid, alpha olefin sulfonic acid and primary alkyl sulfuric acid.

8. A solid detergent composition as claimed in claim 10 or claim 11 wherein said anionic surfactant is a salt of linear alkyl benzene sulfonic acid.

9. A solid detergent composition as claimed in any one of the preceding claims 11 or 12 wherein said salt is an alkaline earth metal salt.

10. A solid detergent composition as claimed in claim 13 where said alkaline earth metal is magnesium.