Title: Flowable Alkyl Ester Sulfonate Composite Powders

FIELD OF THE INVENTION

The present invention relates to a substantially rapid-dissolving flowable alkyl ester sulphonate powder form and the process of making the same. The obtained composite powder is directed to post-addition to the detergent powder formulations and suitable for washing at low temperatures.

BACKGROUND OF THE INVENTION

Methyl ester sulphonates (MES), also having the synonyms a-sulfo fatty methyl ester, alkyl ester sulphonates and sulphonated fatty acid alkyl ester surfactants, has gained much attention as a green and eco-friendly surfactant for laundry and dishwashing in the past decades. MES is synthesized through transesterification and sulphonation from natural oils such as palm and coconut oil, which are renewable and sustainable in comparison to petroleum-derived surfactants. Long carbon chain MES (Ci6 and Cis) has relatively higher detergency power than short chain (C12 and CM) counterparts and other conventional surfactants such as linear alkylbezenesulfonate (LAS) and alkylsulfate (AS). Production of MES from palm feedstock is thus an attractive option.

Compared with LAS and AS, the detergency power of MES is least influenced by the presence of Ca ²⁺ , thereby exhibiting substantially improved calcium hardness tolerance during washing. In addition, MES possesses faster biodegradability, lower skin irritancy and lower aqueous toxicity. MES is also compatible with enzymes, which is a beneficial feature for downstream formulation development. All these striking attributes have made MES an environmentally friendly alternative to LAS and alcohol ethoxysulfates (AES) as a surfactant.

In spite of these outstanding traits, the use of MES has not been developed as speedily as expected, since there are some constraints that impede its broader application. The first hindrance is that MES has a relatively high Krafft point, leading to a low solubility, insufficient stability and slow dissolution in liquid environments. Krafft point is the temperature at which the solubility curve and the critical micellar concentration (cmc) curve meet. Below the Krafft point, most surfactants are undissolved solids and there are no benefits for achieving detergency. It is reported that the Krafft point of MES Cis, C16, C and C12 are 30, 17, 6, and < 0 °C, respectively. It is obvious that MES derived from palm oil has a comparatively higher Kafft point, as the main components of palm oil are Cis and C16 triglycerides. In addition, the production process of MES results in the formation of a MES di-sodium salt by-product, which has a Krafft point of 65 °C, and elevates the Krafft point of the synthesized MES product.

Several strategies have been applied in industrial manufacture of MES to lower the MES Krafft point. These include: (1) minimizing the content of the MES di-sodium salt by-product, for example to be less than 5.0 wt% by complete conversion of the intermediate adduct to methyl ester sulfonic acid prior to neutralization, and by controlling the bleaching and neutralization process parameters to prevent formation of MES di- sodium salt; and (2) maintaining an optimal Cie/Cis ratio of the feedstock, to form a eutectic form which results in the depression of the Krafft point to 15 °C.

The second limitation is that in an aqueous environment, MES is only stable at pH 3 to 9.5, beyond which the ester group is hydrolyzed rapidly, especially at high temperatures. As a consequence, the preferred formulation for MES is in detergent powder formulations, whereby MES is dry-blended at a post addition step. This avoids the potential hydrolytic degradation of MES during high temperature spray drying of alkaline slurries. A dry and flowable MES powder form is a prerequisite to facilitate uniform and continuous post-addition blending. However, MES is normally sticky, poorly flowable and susceptible to agglomeration/caking at ambient conditions due to its low softening/melting point of 40°C to 50 °C.

To overcome this issue, some inorganic materials such as zeolite, clay, sodium sulfate, silicate, starch, diatomite and mixtures thereof, are typically co-processed by milling or spray-drying with MES to minimize stickiness and agglomeration. The co-processed MES composite powder with the aid of inorganic materials is flowable, less agglomerated and easily blended with other detergent powder formulations during a post addition step. Such co-processed powders have moderately sufficient solubility and dissolution rates to satisfy the washing requirement at room temperature of about 25 °C.

However, for short washing times at low temperatures, for example at a temperature range of 7 °C to 10 °C for a duration of 10 minutes, the currently available co-processed MES powders present an unsatisfactory washing performance. White particle residue has been observed on the surface of winter clothes due to insufficient dissolution of co-processed MES powders. To avoid the occurrence of undissolved solids, the MES content in the detergent formulations needs to be reduced substantially from 7 wt% to 3 wt% which significantly reduces its washing power or detergency.

There is therefore a pressing need to develop a flowable powder, that overcomes or at least ameliorates, one or more of the disadvantages described above. Specifically, there is a need for a flowable powder which dissolves rapidly and completely at low temperatures, thereby meeting specific washing requirements.

SUMMARY

In an aspect, there is provided a composite powder comprising a homogeneous mixture of an alkyl ester sulfonate and one or more organic additive, wherein the one or more organic additive is dispersed in the alkyl ester sulfonate to reduce the crystallinity of the alkyl ester sulfonate.

Advantageously, the composite powder as defined above may have significantly better dissolution properties than alkyl ester sulfonate alone. Further advantageously, the remarkable enhancement in dissolution properties may be due to reduction in stickiness and agglomeration of the alkyl ester sulfonate, as well as due to the modified crystalline state, or reduced crystallinity, of the alkyl ester sulfonate. Advantageously, the alkyl ester sulfonate and the organic additive may be blended at a molecular level, so that the organic additive may insert into the crystal lattice of the alkyl ester sulfonate and disrupt the lattice structure. This disruption of the crystal lattice of alkyl ester sulfonate may result in decreased Krafft point and therefore higher dissolution and detergency properties of the alkyl ester sulfonate. Compared with the commercially available methyl ester sulfonate (MES) powders, the dissolution of MES from the composite powder as defined above may be significantly higher, by up to 5 to 7 folds at low temperatures in the range of 5 °C to 30 °C, after 10 minutes of dissolution. In an example, the composite powder may comprise one or more inorganic additive. The inorganic additive may further act to prevent the agglomeration of the composite powder, thereby improving the flowability of the composite powder. In some examples, the inorganic additive may reduce the crystallinity of the alkyl ester sulfonate.

In another aspect, there is provided a method of preparing the composite powder as defined above, the method comprising the step of contacting an alkyl ester sulfonate with one or more organic additive to form a mixture to reduce the crystallinity of the alkyl ester sulfonate.

In an example, the contacting step may comprise kneading, spray-drying, hot-melt-extrusion or solution mixing. Advantageously, the method may facilitate the reduction in crystallinity of the alkyl ester sulfonate, by ensuring that the alkyl ester sulfonate and organic additive are mixed at a molecular level such that the organic additive inserts into the crystal lattice structure of the alkyl ester sulfonate and disrupts the crystal structure.

In another aspect, there is provided a use of the composite powder as defined above as a detergent for washing fabric.

Advantageously, the composite powder may facilitate washing of fabric at low temperatures in the range of about 5 °C to about 30 °C. Further advantageously, the composite powder may be added to detergent powder formulations to enhance the washing power or detergency of the detergent powder formulation.

DEFINITIONS

The following words and terms used herein shall have the meaning indicated:

"Alkyl" as a group or part of a group refers to a straight or branched aliphatic hydrocarbon group. The group may be a terminal group or a bridging group.

The word “substantially” does not exclude “completely” e.g. a composition which is “substantially free” from Y may be completely free from Y. Where necessary, the word “substantially” may be omitted from the definition of the invention.

Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.

As used herein, the term "about", in the context of concentrations of components of the formulations, typically means +/- 5% of the stated value, more typically +/- 4% of the stated value, more typically +/- 3% of the stated value, more typically, +/- 2% of the stated value, even more typically +/- 1% of the stated value, and even more typically +/- 0.5% of the stated value.

Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub -ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Certain embodiments may also be described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the disclosure. This includes the generic description of the embodiments with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a disclosed embodiment and serve to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

Fig. 1 refers to a graph showing the concentration of MES dissolved from MES-new and commercially available MES-P82 at 7°C after 10 minutes.

Fig. 2 refers to a graph showing the X-ray diffraction (XRD) diffraction patterns of MES-P82 and MES- new.

Fig. 3 refers to a graph showing the endothermic differential scanning calorimetry (DSC) curves (in mJ) of MES-P82 and MES-new.

Fig. 4 refers to a graph showing the concentration of MES dissolved from composite MES powder formulated using the solution-mixture-drying method in the presence of different additives

Fig. 5 refers to a graph showing the X-ray diffraction (XRD) patterns of MES composite powder formulated by solution-mixture-drying method and using different additives.

Fig. 6 refers to a graph showing improved low temperature detergency of MES-new and MES -2% PEG20- Stearate as compared with MES-P82 (tergotometer, 8.6 °C/washing 20 minutes, active MES 200 ppm, water hardness 250 ppm, Stained fabric: Sebum-pigment WFK 20D).

Fig. 7 refers to a graph showing differential scanning calorimetry (DSC) curves (in mJ) of MES-P82 and a simple mixture (SM) of MES and 2 wt% AEO-9.

Fig. 8 refers to a graph showing X-ray diffraction (XRD) patterns of MES-P82 and a Simple Mixture (SM) of MES and 2 wt% AEO-9.

Fig. 9 refers to a graph showing the concentration of MES dissolved from MES-new, commercially available MES-P82 and a simple mixture (SM) of MES and 2 wt% AEO-9 at 7°C after 10 minutes. DETAILED DESCRIPTION OF OPTIONAL EMBODIMENTS

There is provided a composite powder comprising a homogeneous mixture of an alkyl ester sulfonate and one or more organic additive, wherein the one or more organic additive is dispersed in the alkyl ester sulfonate to reduce the crystallinity of the alkyl ester sulfonate.

The reduced crystallinity may indicate that the organic additive is molecularly inserted into the lattice structure of the alkyl ester sulfonate to disrupt the molecular structure of the alkyl ester sulfonate. The organic additive may molecularly insert into the crystal lattice of the alkyl ester sulfonate and cause the ordered crystal lattice structure of the alkyl ester sulfonate to become disordered.

The alkyl ester sulfonate may have a stable crystal structure in the P polymorphic form. In the composite powder as defined above, the organic additive may disrupt the crystal lattice of the polymorph on a molecular level so that it becomes less crystalline.

The insertion of the organic additive into the alkyl ester sulfonate to disrupt its molecular structure in the composite powder as defined above may be different from simple mixing (also known as particle mixing) of the organic additive with the alkyl ester sulfonate, where in simple mixing or particle mixing, the organic additive may not disrupt the molecular structure of the alkyl ester sulfonate. That is, in simple mixing, the crystal lattice structure of the alkyl ester sulfonate may not be changed after mixing with the organic additive.

The disruption of the crystal lattice structure of alkyl ester sulfonate by insertion of the organic additive may result in a decrease in Krafft point and therefore higher dissolution and detergency properties of the alkyl ester sulfonate.

The reduction in crystallinity may be by at least 15%, at least 20%, at least 25% or at least 30% compared to alkyl ester sulfonate without organic additive.

The reduction in crystallinity may be by about 30% to about 50%, about 30% to about 35%, about 30% to about 40%, about 30% to about 45%, about 35% to about 40%, about 35% to about 50%, about 40% to about 45%, about 40% to about 50%, or about 45% to about 50% compared to alkyl ester sulfonate without organic additive.

The alkyl ester sulfonate may be a fatty acid methyl ester sulfonate.

The fatty acid methyl ester sulfonate may have a carbon chain length in the range of Cs to C20, preferably C12 tO C18-

The one or more organic additive may be present at an amount of about 0.1 % to about 50 %, about 0.1 % to about 0.2 %, about 0.1 % to about 0.5 %, about 0.1 % to about 1 %, about 0.1 % to about 2 %, about 0.1 % to about 5 %, about 0.1 % to about 10 %, about 0.2 % to about 0.5 %, about 0.2 % to about 1 %, about 0.2 % to about 2 %, about 0.2 % to about 5 %, about 0.2 % to about 10 %, about 0.2 % to about 50 %, about 0.5 % to about 1 %, about 0.5 % to about 2 %, about 0.5 % to about 5 %, about 0.5 % to about 10 %, about 0.5 % to about 50 %, about 1 % to about 2 %, about 1 % to about 5 %, about 1 % to about 10 %, about 1 % to about 50 %, about 2 % to about 5 %, about 2 % to about 10 %, about 2 % to about 50 %, about 5 % to about 10 %, about 5 % to about 50 % or about 10 % to about 50 % by weight of the total weight of the composite powder.

The one or more organic additive may be a surfactant.

The surfactant may be selected from the group consisting of a non-ionic surfactant, an anionic surfactant, a non-ionic emulsifier, a polymer, and any mixture thereof.

The non-ionic surfactant maybe an alcohol ethoxylate.

The alcohol ethoxylate (AE) may be a non-ionic surfactant comprising a hydrophobic alkyl chain or a fatty alcohol, which may be combined with one or more ethoxylate or ethylene oxide units via an ether linkage. The unit number of the ethoxylate may be in the range from 3 to 500.

The anionic surfactant may be selected from the group consisting of sodium laurylsulfate (SLS), sodium laureth sulfate (SLES), linear alkyl sulfonate (LAS), and any mixture thereof.

The polymer may be a water-soluble polymer.

The one or more organic additive may be selected from the group consisting of an alcohol ethoxylate, methyl ester ethoxylate, a fatty alcohol polyethylene ether, soap, polyvinylpyrrolidine, hydroxypropylmethylcellulose (HPMC), sodium laurylsulfate (SLS), sodium laureth sulfate (SLES), linear alkyl sulfonate (LAS), polyethyleneglycol-20-stearate, and any mixture thereof.

The methyl ester ethoxylate may have the formula R-COO-(C2H2O) _n -CH3, where R is a C12-18 alkyl and n is an integer from 10 to 20.

The fatty alcohol polyethylene ether may have the formula RO-(CH2CH2O) _n -H, where R is a C12-18 alkyl and n is an integer from 7 to 25.

The soap may be in the form of a soap noodle, including plant based soaps derived from palm and lauric oils.

The organic additive may be selected from the group consisting of: fatty alcohol polyoxyethylene ether (AEO-9) having the structure RO-(CH2CH2O) _n -H, where R is a C12-18 alkyl and n is 9; fatty alcohol polyoxyethylene ether (AEO-15) having the structure RO-(CH2CH2O) _n -H, where R is a C12-18 alkyl and n is 15; fatty alcohol polyoxyethylene ether (AEO-23) having the structure RO-(CH2CH2O) _n -H, where R is a C12-18 alkyl and n is 23; methyl ester ethoxylate (MEE- 15) having the structure R-COO-(C2H2O) _n -CH3, where R is a C12-18 alkyl and n is 15 polyethyleneglycol-20-stearate; and polyvinylpyrrolidone (CeHgNC n having a molecular weight of 40,000 (PVP-40K)

The organic additive may comprise carbon chains comprising at least 6 carbons, or a polymer chain. The carbon chain or the polymer chain may advantageously insert into the crystal structure of the alkyl ester sulfonate. This may result in the disruption of long distance order in the crystal structure of the alkyl ester sulfonate.

The composite powder may comprise one or more organic additive. The composite powder may comprise one, two, three, four or five different organic additives.

The composite powder may further comprise one or more inorganic additive.

The inorganic additive may act as an anti-caking agent, to stop the alkyl ester sulfonate from agglomerating and thereby improving the flowability of the composite powder. In some examples, the inorganic additive may also disrupt the molecular structure of the alkyl ester sulfonate and reduce the crystallinity of the alkyl ester sulfonate.

The one or more inorganic additive may be present at an amount of about 3% to about 20%, about 3% to about 7%, about 3% to about 10%, about 3% to about 15%, about 7% to about 10%, about 7% to about 15%, about 7% to about 20%, about 10% to about 15%, about 10% to about 20% or about 15% to about 20% by weight of the total weight of the composite powder.

The one or more inorganic additive may be selected from the group consisting of a silicate, an inorganic salt or any mixture thereof.

The silicate may comprise silicon and oxygen and may be selected from the group consisting of zeolite, silica, aluminum-silicate, magnesium silicate, and any mixture thereof.

The one or more inorganic additive may be selected from the group consisting of zeolite, clay, sodium sulfate, diatomite, sodium chloride, NaHCOs, K2SO4, NazCO;. Bentonite, NazSCh and any mixture thereof.

The composite powder may comprise one or more inorganic additive. The composite powder may comprise one, two, three, four or five different inorganic additives.

The composite powder may have a particle size of less than about 1100 pm, less than about 900 pm, less than about 700 pm, less than about 500 pm or less than about 300 pm.

The composite powder may have a particle size of about 10 pm to about 1100 pm, about 10 pm to about 20 pm, about 10 pm to about 50 pm , about 10 pm to about 100 pm, about 10 pm to about 200 pm, about 10 pm to about 500 pm, about 10 pm to about 1000 pm, about 20 pm to about 50 pm, about 20 pm to about 100 pm, about 20 pm to about 200 pm, about 20 pm to about 500 pm, about 20 pm to about 1100 pm, about 50 pm to about 100 pm, about 50 pm to about 200 pm, about 50 pm to about 500 pm, about 50 pm to about 1100 pm, about 100 pm to about 200 pm, about 100 pm to about 500 pm, about 100 pm to about 1100 pm, about 200 pm to about 500 pm, about 200 pm to about 1100 pm, or about 500 pm to about 1100 pm. A method of preparing the composite powder as defined above, the method comprising the step of contacting an alkyl ester sulfonate with one or more organic additive to form a mixture to reduce the crystallinity of the alkyl ester sulfonate.

The contacting step may be performed in an aqueous substrate. The aqueous substrate may be water.

The mixture may be a solution or a suspension.

The method may further comprise the step of mixing the mixture with one or more inorganic additive.

The mixing may be by milling. Where the inorganic additive is a silicate, the mixing may be by milling.

The milling may be performed using a mortar and pestle or using a ball mill, or a knife hammer mill.

The knife hammer mill may comprise a mesh sifter.

The mixing may be part of the contacting step. That is, the one or more in organic additive may be contacted with the alkyl ester sulfonate and the one or more organic additive. Where the one or more inorganic additive is an inorganic salt, the inorganic salt may be contacted with the alkyl ester sulfonate and the one or more organic additive.

The contacting step may be performed at temperatures greater than about 40 °C. The contacting step may be performed at temperatures in the range of about 40 °C to about 250 °C.

The contacting step may be performed by kneading the mixture, preferably at a temperature in the range of about 70 °C to about 110 °C, about 70 °C to about 90 °C or about 90 °C to about 110 °C.

The contacting step may be performed by spray-drying the mixture, preferably at a temperature in the range of about 120 °C to about 200 °C, about 120 °C to about 140 °C, 120 °C to about 160 °C, 120 °C to about 180 °C, about 160 °C to about 200 °C, or about 180 °C to about 180 °C, 140 °C to about 160 °C, 140 °C to about 180 °C, about 140 °C to about 200 °C, about 160 °C to 200 °C.

Prior to the spray-drying step, the method may further comprise the step of dissolving the alkyl ester sulfonate and the one or more organic additive in a solvent, preferably water.

The contacting step may be performed by hot-melt-extrusion of the mixture, preferably at a temperature in the range of about 80 °C to about 110 °C, about 80 °C to about 90 °C, about 80 °C to about 100 °C, about 90 °C to about 100 °C, about 90 °C to about 110 °C, or about 100 °C to about 110 °C.

The contacting step may be performed by solution mixing of the mixture, preferably at a temperature in the range of about 40 °C to about 60 °C, about 40 °C to about 50 °C, or about 50 °C to about 60 °C.

The solution mixing may be performed in a solvent, preferably water.

The method may further comprise the step of drying the solution to remove the solvent.

The method may further comprise the step of crushing the composite powder so that the composite powder has a particle size of less than 1100 pm. There is also provided a composite powder prepared by the method as defined above.

There is also provided the use of the composite powder as defined above as a detergent for washing fabric.

The washing may be performed at low temperatures. The washing may be performed at a temperature in the range of about 5 °C to about 30 °C, about 5 °C to about 10 °C, about 5 °C to about 15 °C, about 5 °C to about 20 °C, about 5 °C to about 25 °C, about 10 °C to about 15 °C, about 10 °C to about 20 °C, about 10 °C to about 25 °C, about 10 °C to about 30 °C, about 15 °C to about 20 °C, about 15 °C to about 25 °C, about 15 °C to about 30 °C, about 20 °C to about 25 °C, about 20 °C to about 30 °C, or about 20 °C to about 25 °C.

The fabric may comprise cotton, polyester, silk, wool and any blend thereof.

The composite powder as defined above may be added to detergent powder formulations to enhance the washing power of the detergent powder formulation. The composite powder as defined above may function as a surfactant in the detergent powder formulation.

EXAMPLES

Non-limiting examples of the invention will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

Methods

Dissolution Test

Dissolution of methyl ester sulfonate (MES) was evaluated by measuring the concentration of MES dissolved within 10 minutes of placing the composite powder in water. In brief, 1.0 g of the composite powder was added to 100 g pre-cooled deionized water followed by shaking at 100 rpm for 10 minutes at a temperature of 7 °C. The suspension was quickly transferred to a pre-cooled centrifuge tube, centrifuged at 7 °C for 1.5 minutes and filtered with a syringe filter (Pall Corporation, New York, USA) (pore size 0.45 pm) with a pre-cooled syringe (Henke-SASS-Wolf, Tuttlingen, Germany ) to obtain a clear solution of MES. The MES concentration was measured by two-phase titration using methylene-blue (Signa- Aldrich, St. Louis, Missouri, USA) as the indicator.

Detergency Test

Cold washing detergency test was performed in a tergotometer (Copley Scientific, Nottingham, UK) at 8.6 °C. Each vessel was filled with 1.0 L of water having a hardness of 250 ppm and the temperature was controlled at 8.6 °C. 0.266 g of MES-P82 or the inventive composite powder containing 0.20g of MES was added to each vessel, followed by addition of 10 pieces of numbered, WFK-20D standard sebum-pigment soiled polyester-cotton blend fabric (Testfabrics Inc., West Pittston, Pennsylvania, US). The washing was conducted for 20 minutes at a stirring rate of 180 rpm.

Once the washing cycle was completed, all soiled fabrics were retrieved using a meshed filter in the sink and transferred to a twin tub washing machine (Tecno, Singapore) to be spun for one minute to remove excess water, followed by rinsing with 20 L of tap water for 5 minutes and finally spinning for another one minute. The wet soiled fabrics were sandwiched between two pieces of A3 sized paper and dried by ironing.

The whiteness was determined using a X-rite Ci7600 photo-spectrometer (Grand Rapids, Michigan, USA) and detergency was calculated using the Z-value before and after washing. The amount of active MES used was the same for all samples.

The efficiency of removal of soiling from fabrics was calculated using the Kubelka-Munk equation:

K/S= (1-R ² )/(2R) (equation 1) wherein K is the coefficient of reflectivity, S is the coefficient of light scattering, R is the observed reflectivity for monochromatic light (Z/100 value to be measured by photo-spectroscopy).

It should be noted that the Z value is a score parameter of photo reflectance that is correlated with the cleanliness of the fabric, and was measured using a photo-spectrometer and. For example, for white fabric, the Z value is typically high (about 0.9) whereas for a carbon-stained fabric, the Z value may be 0.1 or lower. Once staining is removed from the fabric, the Z value of the fabric will increase.

The percent removal of black particles from the soiled fabric was calculated by the following equation:

Detergency (%)= (K7S for soiled fabric - K7S for washed fabric) / ( K7S for soiled fabric - K7S for unsoiled fabric) x 100 (equation 2)

X-Ray Diffraction

X-Ray diffraction measurements were performed on a D8-ADVANCE X-ray diffractometer (Bruker, Billerica, Massachusetts, USA) in steps of 0.02° using Cu Ka radiation as the X-ray source.

Differential Scanning Calorimetry (DSC)

DSC scans were performed on DSC6000 Modulated Temperature DSC (MT-DSC) (Perkin Elmer, Waltham, Massachusetts, USA). 5 mg of sample was used for each scan with a heating rate of 10 °C/min.

Example 1: Hot Kneading Method

Mizulan MES flakes (Global Eco Chemicals Malaysia Sdn. Bhd, Pasir Gudang, Johor, Malaysia; PT Global Eco Chemicals Indonesia, Kebomas, Gresik, Indonesia) were heated to 90 °C in a S12 KRC kneader (Kurimoto Ltd., Osaka, Japan) to form a slurry, on to which certain amounts of fatty alcohol polyoxyethylene ether having the formula RO-(CH2CH2O) _n -H, where R is a C12 isalkyl chain and n is 9 (AEO-9, Petronas Chemicals Group Bhd, Kuala Lumpur, Malaysia), was sprayed, such that the resulting composite powder comprised 2 wt% AEO-9 and 98 wt% MES. Specifically, one ton of MES flakes were fed into the kneader continually and 20 kg AEO-9 was sprayed on top of the MES flakes to be mixed with the MES and then heated to about 90 °C. The mixture was kneaded intensively, then extruded into noodles using an extruder (Kurimoto Ltd., Osaka, Japan) and cooled at room temperature. The obtained MES noodles were crushed in the presence of 5 wt% to 15 wt% zeolite 4A powder (Thai Silica Chemicals, Bangkok, Thailand) using a Knife Hammer mill with mesh sifter (Hosokawa Micron Corporation, Osaka, Japan) to control the particle size to be below 1100 pm. The formed MES composite powder was denoted MES-new.

Other additives such as Soap noodle9010 (Wilmar, Singapore), NaHCO; (ORC Chem Technologies Sdn Bhd, Shah Alam, Selangor, Malaysia), K2SO4 (Sigma-Aldrich, St. Louis, Missouri, USA), NazSO4 Kumpulan Saintifik F.E. Sdn Bhd, Petaling Jaya, Selangor Malaysia), sodium laurylsulfate (SLS) (PT KAO Indonesia, South Jakarta City, Jakarta, Indonesia), and C18-MEE (methyl ester ethoxylate (C18-MEE) having the structure R-COO-(C2H2O) _n -CH3, where R is a C16-18 alkyl and n is 10-12) (Global Eco Chemicals Malaysia Sdn. Bhd, Pasir Gudang, Johor, Malaysia), were also tested in place of AEO-9 and the composite powder was manufactured under the same hot kneading conditions. Amongst all the MES kneaded with additives, the composite powder comprising AEO-9 and MES exhibited the best performance.

A comparison was made between MES-new and commercially available MES powder (MES-P82, Wilmar, Singapore). MES-P82 is prepared by directly crushing Mizulan with anti-caking zeolite powder. In this regard, the MES in MES-P82 is fundamentally the same as the MES in Mizulan flake except that it has a smaller particle size. The solubility of MES-P82 is low and requires improvement. In contrast, MES-new is processed with an organic additive to reduce crystallinity before crushing with anticaking zeolite. Effectively, by comparing MES-new to MES-P82, the properties of MES in Mizulan before and after processing with an organic additive can be assessed.

The concentration of dissolved MES observed for MES-P82 was 431ppm after 10 minutes of dissolution at 7 °C. Comparatively, the dissolved MES concentration from MES-new was as high as 2837 ppm under the same conditions, indicating a greater than 5-fold enhancement in dissolution, as shown in Fig. 1.

The crystallinity of MES powder was characterized by X-ray diffraction. As shown in Fig. 2, the substantially lower diffraction intensity of MES-new compared to that of MES-P82 indicated a low crystallinity of MES-new.

Fig. 3 shows the differential scanning calorimetry (DSC) curves of MES-P82 and MES-new. The reduced endothermic peaks of MES-new indicated a reduced crystallinity compared to MES-P82. In Fig. 3, the crystallinity of the MES is correlated with the AH (change in enthalpy) calculated based on the integrated peak area. MES-P82 had a AH of 107.05 J/g, while MES-new had a AH of 63.97 J/g. This showed that the crystallinity of MES-new was reduced by 40% as compared with MES-P82.

Example 2: Co-Spray Drying Method

A spray drying process was developed to convert a solution mixture or a suspension mixture of MES and additive to a solid powder. Specifically, a mixed suspension with total solid content of 20 wt% was prepared for co-spray drying. A sample of MES composite particles was designed to comprise MES (49.0 wt%), Zeolite (7.5 wt%) (Thai Silica Chemicals, Bangkok, Thailand), AEO-7 (1.0 wt%) (Petronas Chemicals Group Bhd, Kuala Lumpur, Malaysia ) and Silica (42.5 wt%) (Sigma-Aldrich, St. Louis, Missouri, USA). Typically, 9.8 g of MES and 0.2 g AEO-7 was dissolved in 80 g of water and mixed with 1.5 g of zeolite and 8.5 g of silica powder to form a suspension. The mixture was then transferred to a mini spray dryer unit (Buchi, Switzerland) in a closed loop system with dehumidification. The mixture was pumped at a rate of approximately 0.3 kg/hour from a storage bottle under stirring to an atomizing device, which was located in an air disperser at the top of the spray drying chamber. The drying air was drawn from the atmosphere via a filter using a supply blower fan and was passed through an air heater which was heated to 150 °C at the inlet of the drying chamber. The mixture was rapidly dried in the drying chamber, followed by separation of the particles in a cyclone.

The preparation was repeated with 2 wt% of soluble polymer (PVP-40K) (Sigma-Aldrich, St. Louis, Missouri, USA) and 2 wt% non-ionic surfactant AEO-23 (Petronas Chemicals Group Bhd, Kuala Lumpur, Malaysia).

The dissolution outcome of MES from various composite powders prepared in this manner is shown in Table 1.

Table 1. Composite powders samples formed using the co-spray drying method

Example 3: Hot-Melt Extrusion (HME) Method

Hot-melt extrusion (HME) is a continuous process for preparing solid dispersions with an increased solubility. This technique was applied to prepare an MES composite powder with additive by continuous mixing, in-situ melting and extrusion to obtain solid noodles. The obtained MES noodles were cooled at room temperature and crushed in the presence of 5 wt% to 15 wt% zeolite 4A powder (Thai Silica Chemicals, Bangkok Thailand) to obtain the MES composite powder.

Specifically, 0.47 g of AEO-9 was sprayed onto 19.5 g of MES followed by feeding and extruding using a Prism Eurolab 16 Melt Extruder (Thermo Scientific, Karlsruhe, Germany) at 90 °C .

The obtained composite powder was able to achieve 1500 ppm of dissolved MES at 7°C for 10 minutes, which was more than 3-times that of commercial MES-P82 dissolved under the same conditions.

Example 4: Solution-Mixture-Drying Method

A solution-mixture-drying method was developed to obtain composite powders comprising MES and additive by mixing MES and additive in a solution, followed by drying under stirring and further drying in an oven. Specifically, 29.4 g MES and 0.6 g of additive (AEO-9, AEO-15 and AEO-23 obtained from Petronas Chemicals Group Bhd, Kuala Lumpur, Malaysia; MEE-15 (Jiangsu Qichen New Materials, Rugao City, Jiangsu, China), PEG20-Stearate (ErcaWilmar, Singapore), PVP40K (Sigma-Aldrich, St Louis, Missouri, USA) was dissolved in 70 g of water at 50 °C under stirring to form a solution. This was followed by continuous stirring to evaporate most of the water. The resulting viscous slurry was further dried at 80 °C in an oven to form dried MES flakes. This was further mixed with 15 wt% zeolite 4A and the flakes were crushed into a powder to obtain particles having a diameter of less than 840 microns. The resulting composite powders were denoted MES-2%AEO-9, MES-2%AEO-15, MES-2%AEO-23, MES- 2%MEE-15, MES-2%PEG20-Stearate and MES-2%PVP40K, respectively.

As shown in Fig. 4, the presence of 2wt% additive in the MES composite powder resulted in significant enhancement of MES dissolution. With 2 wt% PEG20-Stearate or AEO-23 (Petronas Chemicals Group Bhd, Kuala Lumpur, Malaysia), denoted MES-2%PEG20-Stearate and MES-2% AEO-23, respectively, the concentration of dissolved MES at 7 °C was 3200 ~ 3700 ppm, which was about 7-fold higher than that of commercial MES-P82.

Fig. 5 shows the X-ray diffraction (XRD) patterns of MES-additive composites and that of the commercial MES-P82. The intensity of the X-ray diffraction peaks of MES-additive composites were clearly weaker than MES-P82, indicating a reduced crystallinity of the composite MES. A presence of 2 wt% of additives effectively reduced the ordered arrangement of MES molecules and retarded the crystal growth of MES during the drying process. The reduced crystallinity was also confirmed by DSC measurement.

The solution-mixture-drying method can be applied to the current processes used in the MES manufacture industry to achieve rapidly-dissolving MES composite powders in a one-step synthesis.

For example, during the industrial manufacturing process of an alkyl ester sulfonate, palm oil is reacted with an alcohol such as methanol to form an alkyl ester. This is followed by sulfonation to form alkyl ester sulfonate (or MES if the alcohol is methanol). The alkyl ester sulfonate is subsequently neutralized with a base such as NaOH to remove any excess acid, and bleached with a peroxide such as H2O2 to decolour the alkyl ester sulfonate product. Finally, the product is dried to yield flakes.

In the above regard, the 2 wt% additive solution may be added to the neutralization step or the bleaching step, followed by drying. Despite such a minor modification in the process, this will be able to facilitate manufacture of MES composite powders with adequate dissolution properties for low temperature washing.

Example 5: Detergency

The detergency calculated when MES-new and MES-2% PEG20-Stearate were used, was higher than that when commercial MES-P82 was used, as shown in Fig. 6. The improvement in detergency was attributed to the enhanced dissolution of MES-new and MES-2% PEG20-Steartae. The rapid dissolution of MES from MES-new and MES-2% PEG20-Stearate was able to release more surfactant molecules of MES in water, facilitating the removal of stains from the fabric.

Comparative Example 1: Simple Mixing and Molecular Mixing

The properties of MES-new was compared with a simply mixed mixture of MES and organic additive (AEO-9). In the simply mixed mixture of MES and organic additive, MES and 2wt% of AEO-9 were simply mixed by stirring under ambient conditions without undergoing hot kneading, spray-drying, hot-melt- extrusion or solution mixing at elevated temperatures. The simply mixed mixture was denoted MES-AEO9- SM. Fig. 7 and Fig. 8 show the DSC and XRD scans, respectively, of MES-new and MES-AEO9-SM, which indicate that the crystallinity of MES is not obviously changed by simple mixing of MES with 2 wt% AEO- 9.

Fig. 9 is a graph comparing the concentration of dissolved MES between MES-new, MES-P82 and MES- AE09-SM after 10 minutes of dissolution at 7 °C. MES-new shows an over 5-fold increase in dissolution compared to MES-P82 and MES-AEO9-SM.

In MES-new, the MES and 2 wt% AEO-9 were hot-kneaded together, and Fig. 7 to Fig. 9 clearly show that the kneading process changed the molecular arrangement of the MES in MES-new to reduce crystallinity, thereby resulting in significant improvement in its dissolution characteristics.

INDUSTRIAL APPLICABILITY

The composite powder as defined above may be useful in low-temperature (5 °C to about 30 °C) washing of fabrics, for example during winter when the temperatures are generally low.

It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.