WO2023041461A1

WO2023041461A1 - Process for preparing a spray dried detergent particle

Info

Publication number: WO2023041461A1
Application number: PCT/EP2022/075217
Authority: WO
Inventors: Abraham Chacko; Girish Kumar; Sharavan KUMAR; Kunal Shankar PAWAR; Nadeem Shaikh; Satyendra Prasad SINGH
Original assignee: Unilever Ip Holdings B.V.; Unilever Global Ip Limited; Conopco, Inc., D/B/A Unilever
Priority date: 2021-09-15
Filing date: 2022-09-12
Publication date: 2023-03-23
Also published as: CN117897471A

Abstract

The present invention relates to a process for preparing a spray-dried detergent particle. Particularly to spray-dried laundry detergent particles with low pH, low alkalinity and have good particle characteristics. It is thus an object of the present invention to provide a process for preparing a spray dried detergent particle having low pH and low alkalinity. It is yet another object of the present invention to provide a spray dried detergent particle with low levels of alkaline builders such as carbonate and silicate and yet having good powder properties over extended storage periods.The present inventors have found that a spray dried detergent particle having an in-situ formed organic carboxylate salt of alkaline earth metal provides for excellent powder properties and extended shelf life without getting caked. It is also surprisingly found that the spray-dried particle provides desired pH in wash solution required for good stain removal performance without being harsh on the hands or the fabrics.

Description

PROCESS FOR PREPARING A SPRAY DRIED DETERGENT PARTICLE

Field of the invention

The present invention relates to a process for preparing a spray-dried detergent particle. Particularly to spray-dried laundry detergent particle with low pH, low alkalinity and having good particle characteristics. The spray-dried detergent particle is suitable for use as a solid laundry detergent composition or for incorporation into a solid laundry detergent composition.

Background of the invention

Traditionally, powder detergent compositions have been formulated to provide a pH ranging from 10.5 to 11 .5 in a wash solution. A basic pH ensures that the surfactant systems, enzymes, and other ingredients in the composition remain solubilized in the wash water, thereby promoting effective soil release and cleaning performance. Cotton fabric swells at a pH of 9.5 to 10, which allows the surfactant to penetrate deeply into the fibre. Furthermore, a basic pH ensures effective removal of fatty and particulate stains from soiled clothing.

Despite the above-mentioned advantages, the higher pH also has certain disadvantages. Higher pH in the wash solution tends to be harsh on the skin of consumers and are associated with the problem of colour fading of the laundered fabrics.

Consumers prefer laundry detergent composition which are milder on the skin. Particularly, consumers laundering fabrics by hand, prefer composition which deliver good cleaning performance while being mild to the skin and offering a desirable feel while washing. Further consumers also prefer detergent composition which deliver good foam during washing which is easily rinsed off at a later stage.

In the past, such milder compositions have been formulated by lowering the pH of the composition. Formulating a low pH composition necessitates significantly reducing or completely removing the alkaline ingredients such as sodium carbonate and sodium silicate. The sodium carbonate and sodium silicate not only provide a wash liquor pH of around 10.5, but they also function as effective builders to sequester Ca and Mg ions present in hard water. Beside these benefits, sodium carbonate and sodium silicate contribute to improving the physical properties such as flow and storage behaviours of the spray-dried detergent particle. Past attempts at reducing or eliminating sodium carbonate from the spray-dried detergent particle were not satisfactory as the resultant spray-dried detergent particle were found to have acceptable powder properties only for a short duration that is immediately after spray drying and showed caking on storage.

Along with sodium carbonate, sodium silicate is generally considered a critical ingredient in spray-dried detergent particle as it serves to provide stability and integrity to the detergent particle formed during the spray-drying operation. Several attempts to reduce or eliminate sodium silicate resulted in deterioration of powder properties with respect to flow and caking tendency. Sodium silicate also plays a role in the viscosity and flow behaviour of the slurry, a low silicate containing slurry may cause gelation of the slurry and the slurry may be not pumpable.

Hence, preparing a low pH spray-dried detergent particle has been a challenge in the past where the particle possesses good powder flow properties especially on prolonged storage.

US4294718A (Colgate-Palmolive, 13/10/1981) discloses a non-gelling aqueous slurry of inorganic salt mixture having bicarbonate, carbonate, and silicate. It discloses that a combination of magnesium sulfate and citric acid or water-soluble derivatives thereof provides a greater anti-gelling effect. The levels of the alkaline ingredients used are high and the composition on a solid basis includes 55 to 85 wt.% sodium bicarbonate, 5 to 25 wt.% sodium carbonate and 5 to 25 wt.% sodium silicate.

EP 3546556 A1 (The Procter & Gamble Company, 2021) discloses a process for preparing a spray-dried laundry detergent particle which provides a lower bulk density. The process involves the step of contacting water-insoluble magnesium silicate salt to monomeric organic carboxylic acid to form silica. The spray dried particle is substantially free of carbonate salt.

It is thus an object of the present invention to provide a process for preparing a spray dried detergent particle having low pH and low alkalinity. It is yet another object of the present invention to provide a spray-dried detergent particle which ensures good fabric care profile and is gentle to hand while maintaining good cleaning performance, at a low pH and low alkalinity profile of the laundry detergent composition.

It is yet another object of the present invention to provide a spray dried detergent particle with low levels of alkaline builders such as carbonate and silicate and yet having good powder properties over extended storage periods.

It is yet another object of the present invention to provide a spray dried detergent particle having low pH and low alkalinity, which is substantially free of carbonate, zeolite and STPP.

It is yet another object of the present invention to provide a spray-dried particle which shows improved anti-ashing properties on multiple washes and deposits low or no insoluble residues on laundered fabrics.

Summary of the invention

The present inventors have found that a spray dried detergent particle having an in-situ formed organic carboxylic acid salt of alkaline earth metal provides for excellent powder properties and extended shelf life without getting caked. It is also surprisingly found that the spray-dried particle provides desired pH in wash solution required for good stain removal performance without being harsh on the hands or the fabrics.

The spray-dried detergent particle according to the present invention providing one or more of the above-mentioned benefits while incorporating low or no alkaline builders, particularly alkali metal carbonates and alkali metal silicates. Preferably the spray-dried detergent particle includes less than 2 wt.% alkali metal silicate. Preferably the spray-dried particle is substantially free of alkali metal carbonate.

According to a first aspect of the present invention, disclosed is a process for preparing a spray dried laundry detergent particle, said process comprising the steps of:

(i) reacting an alkali metal silicate salt and an alkaline earth metal compound in an aqueous mixture to form an in-situ intermediate mixture comprising one or more compound selected from the group consisting of hydroxide of alkaline earth metal, silicate salt of alkaline earth metal, disilicate salt of alkaline earth metal or mixtures thereof;

(ii) contacting the in-situ intermediate mixture having one or more compound selected from the group consisting of hydroxide of alkaline earth metal, silicate salt of alkaline earth metal, disilicate salt of alkaline earth metal or mixtures thereof with an organic carboxylic acid to form a base mixture comprising organic carboxylic acid salt of alkaline earth metal;

(iii) adding an amount of an alkaline source to the base mixture to provide an aqueous slurry having a pH of 4 to 8.5, wherein the aqueous slurry comprises an organic carboxylic acid salt of alkaline earth metal and a detersive surfactant; and,

(iv) spray-drying the aqueous slurry to form a spray-dried laundry detergent particle.

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. 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 xto y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed description of the invention

Process of making a spray-dried detergent particle

According to a first aspect of the present invention disclosed is a process of preparing a spray- dried detergent particle comprising the steps as described herein below.

Step (T): Reacting an alkali metal silicate salt with an alkaline earth metal compound According to the first aspect of the present invention disclosed is a process of reacting an alkali metal silicate salt and an alkaline earth metal compound in an aqueous mixture to form an in- situ intermediate mixture comprising one or more compound selected from the group consisting of hydroxide of alkaline earth metal, silicate salt of alkaline earth metal, disilicate salt of alkaline earth metal or mixture thereof. Preferably the in-situ formed silicate salt of alkaline earth metal and/or the disilicate salt of alkaline earth metal is amorphous.

Alkali metal silicate salt:

The process according to the first aspect of the present invention includes addition of an alkali metal silicate salt to the aqueous mixture. Alkali metal silicate salt is a common ingredient in the laundry detergent composition. The alkali metal silicate salt preferably has a weight ratio of SiC>2:M2O within the range of 1 .6 to 3.3 more preferably 1 .6 to 2.4, and most preferably 2.0 to 2.85, wherein M is an alkali metal. The alkali metal silicate salt employed is preferably in the form of an aqueous solution, generally having a solid content from 30 wt.% to 45 wt.% by weight of the aqueous solution.

Preferably the alkali metal silicate salt may be selected from the group consisting of sodium silicate, potassium silicate, sodium-potassium double silicate or mixtures thereof. Preferably the alkali metal silicate salt is water-soluble. Preferably the alkali metal silicate salt employed is sodium silicate. Preferably the sodium silicate has a weight ratio, SiC>2:Na2O within the range of 1 .6 to 3.3 more preferably 1 .6 to 2.4, and most preferably 2.0 to 2.85.

Preferably the amount of alkali metal silicate added to the aqueous mixture is such that the spray-dried detergent particle formed preferably comprises less than 5 wt.% still preferably less than 2 wt.% alkali metal silicate salt, still preferably less than 1 wt.%.

Alkaline earth metal compound:

The alkaline earth metal compound is preferably selected from a magnesium salt, a calcium salt or mixtures thereof. The alkaline earth metal salt may be preferably selected from calcium sulphate, magnesium sulphate, calcium chloride, magnesium chloride or mixtures thereof. Preferably the alkaline earth metal compound is a magnesium salt and still preferably the alkaline earth metal compound/salt is magnesium sulphate.

Aqueous mixture:

The aqueous mixture preferably comprises a detersive surfactant. Suitable detersive surfactant includes anionic, nonionic, cationic, amphoteric, zwitterionic detersive surfactant or mixtures thereof. Suitable detersive surfactant may be linear or branched, substituted or un-substituted. The detersive surfactant may be derived from petrochemical material or is bioderived.

Preferably the detersive surfactant is anionic, nonionic or mixtures thereof. More preferably the aqueous mixture includes an anionic surfactant. Suitable anionic detersive surfactant is an alkyl sulphonate surfactant, alkyl sulphate surfactant or mixtures thereof. The anionic surfactant and/or nonionic surfactant may be linear or branched, substituted or unsubstituted.

Anionic detersive surfactant: The aqueous mixture preferably includes a detersive surfactant. The detersive surfactant is preferably an anionic surfactant. The detersive anionic surfactant is either pre-neutralized and added into the aqueous mixture or a liquid acid form of the anionic surfactant is added to the aqueous mixture and neutralized in-situ. Alternately, the acid form of the anionic surfactant may be partly neutralized and thereafter added into the aqueous mixture such that the remaining un-neutralized part of the liquid acid form of the anionic surfactant is neutralized in-situ in the aqueous mixture. Fully pre-neutralized anionic surfactant commercially available in solid form or in the form of paste may also be suitably used. Preferably the detersive surfactant is added to the aqueous mixture before addition of the alkaline earth metal compound. In some embodiments the detersive surfactant, especially in the fully pre-neutralized salt form is added to the aqueous mixture after addition of the alkaline earth metal compound/salt or along with the alkaline earth metal compound/salt. In further embodiments the detersive surfactant in the fully neutralized salt form may be added to the base mixture after the formation of the organic carboxylic acid salt of alkaline earth metal.

When the detersive surfactant is added into the aqueous mixture in the form of a partly neutralized anionic surfactant, the partly neutralized anionic surfactant is preferably prepared by a neutralization process which involves the step of (i) mixing a liquid acid form of the anionic surfactant and a neutralizing agent to form a partially neutralized solution; preferably the neutralizing agent is an alkali metal hydroxide, wherein the amount of alkali metal hydroxide neutralizing agent is sufficient to react with a portion of liquid acid anionic surfactant precursor to form in-situ anionic surfactant salt. The neutralized anionic surfactant formed by neutralizing the acid form with the alkali metal hydroxide neutralizing agent preferably contributes from 28 parts to 98 parts of the total anionic surfactant by weight present in the spray-dried detergent particle. On addition of alkali metal silicate salt to the partly neutralized anionic surfactant in the aqueous mixture, the remaining unreacted acid form of the anionic surfactant reacts with the alkali metal silicate salt to form fully neutralized salt form of the anionic surfactant. In one embodiment of the present invention a fully neutralized anionic surfactant is added to the aqueous mixture. In this embodiment the liquid acid anionic surfactant precursor is reacted with an alkali metal hydroxide to form fully neutralized anionic surfactant salt before addition to the aqueous mixture. More preferably the liquid acid precursor of the anionic surfactant is partly or fully neutralized in-situ. One or more anionic surfactant may be present in the spray-dried detergent particle.

Typically, the detersive surfactant is present in the aqueous mixture when the alkaline earth metal compound or salt is contacted with the alkali metal silicate salt. The order of addition is to contact the pre-neutralized detersive surfactant or the acid precursor form of the anionic detersive surfactant with water followed by contacting with the alkali metal silicate salt and then adding the alkaline earth metal compound or salt. Preferably the part or full neutralization may be carried out in the same vessel by contacting the acid precursor form of the anionic surfactant with an aqueous solution of neutralizing agent (alkali metal hydroxide) to form the neutralized anionic surfactant. Alternately in the process of the present invention, the order of addition may be reversed wherein the step involves adding alkaline earth metal compound or salt to the aqueous mixture followed by the alkali metal silicate salt.

When the detersive surfactant is pH sensitive that is those which undergo hydrolysis at low pH conditions, then it is preferred that the detersive surfactant is added to the aqueous slurry after the pH is raised to 7 or above. Non-limiting examples of the detersive surfactant is primary alkyl sulphate surfactant. Preferably PAS has an alkyl chain length of Cs to C , preferably C12 to C14. Preferably the primary alkyl sulphate surfactant is linear or branched, preferably linear. Preferably the primary alkyl sulphate surfactant is substituted or unsubstituted.

Preferably the detersive surfactant is an anionic surfactant. Suitable anionic detersive surfactant includes sulphonate and sulphate surfactant. Suitable sulphonate surfactant include alkyl ester sulphonate, alpha olefin sulphonate, alkyl benzene sulphonate, especially alkyl benzene sulphonate, preferably Cw to Cw alkyl benzene sulphonate. A preferred detersive anionic surfactant is linear alkyl benzene sulphonate, where the alkyl chain has 5 to 20 carbon atoms, more preferably the linear alkylbenzene sulphonate surfactant has a Cw to Cw alkyl group, still preferably Cw to C alkyl group. Suitable alkyl benzene sulphonate (LAS) is obtainable, preferably obtained, by sulphonating commercially available linear alkyl benzene (LAB); suitable LAB includes low 2-phenyl LAB, other suitable LAB includes high 2-phenyl LAB, such as those supplied by Sasol under the tradename Hyblene®. Suitable sulphate surfactant includes alkyl sulphate, preferably Cs to C alkyl sulphate, or predominantly C12 to C alkyl sulphate. A preferred sulphate detersive surfactant is alkyl alkoxylated sulphate, preferably alkyl ethoxylated sulphate, preferably a Cs to C alkyl alkoxylated sulphate, preferably a Cs to C alkyl ethoxylated sulphate, preferably the alkyl alkoxylated sulphate has an average degree of alkoxylation from 0.5 to 20, preferably from 0.5 to 10, preferably the alkyl alkoxylated sulphate is a Ca to C alkyl ethoxylated sulphate having an average degree of ethoxylation of from 0.5 to 10, preferably from 0.5 to 5, more preferably from 0.5 to 3 and most preferably from 0.5 to 1 .5. The alkyl sulphate, alkyl alkoxylated sulphate and alkyl benzene sulphonate may be linear or branched, substituted or un-substituted and may be derived from petrochemical material or biomaterial. Other suitable anionic detersive surfactant includes soaps, alkyl ether carboxylates. Suitable anionic detersive surfactant may be in salt form, suitable counter-ions include sodium, calcium, magnesium, amino alcohol, and any combinations thereof. A preferred counterion is sodium.

Suitable non-ionic detersive surfactant are selected from the group consisting of: Cs to C alkyl ethoxylates, such as, NEODOL® non-ionic surfactants from Shell; Cs to C12 alkyl phenol alkoxylates wherein preferably the alkoxylate units are ethyleneoxy units, propyleneoxy units or a mixture thereof; C12 to C alcohol and Cs to C12 alkyl phenol condensates with ethylene oxide/propylene oxide block polymers such as Pluronic® from BASF; alkyl polysaccharides, preferably alkyl polyglycosides; methyl ester ethoxylates; polyhydroxy fatty acid amides; ether capped poly(oxyalkylated) alcohol surfactants and mixtures thereof.

Suitable non-ionic detersive surfactants are alkyl polyglucoside and/or an alkyl alkoxylated alcohol. Suitable non-ionic detersive surfactants include alkyl alkoxylated alcohols, preferably Cs to Cis alkyl alkoxylated alcohol, preferably a Cs to Cis alkyl ethoxylated alcohol, preferably the alkyl alkoxylated alcohol has an average degree of alkoxylation of from 1 to 50, preferably from 1 to 30, or from 1 to 20, or from 1 to 10, preferably the alkyl alkoxylated alcohol is a Ca to Cis alkyl ethoxylated alcohol having an average degree of ethoxylation of from 1 to 10, preferably from 1 to 7, more preferably from 1 to 5 and most preferably from 3 to 7. The alkyl alkoxylated alcohol can be linear or branched and substituted or un-substituted. Suitable nonionic detersive surfactants include secondary alcohol-based detersive surfactants.

Zwitterionic surfactant: Suitable zwitterionic detersive surfactants include amine oxides and/or betaines. One or more detersive surfactant may be present in the spray-dried detergent particle according to the present invention. The surfactant is preferably those which are thermally stable during processing conditions of a spray-drying tower where typically the inlet air temperature ranges from 250°C to 500°C and those which are chemically stable at the pH conditions of the spraydrying slurry. Non-limiting examples of the anionic surfactant includes the ones mentioned above.

Forming in-situ intermediate mixture:

The alkali metal silicate salt reacts with the alkaline earth metal compound in an aqueous mixture to form an in-situ intermediate mixture. The intermediate mixture includes one or more compound selected from the group consisting of hydroxide of alkaline earth metal, silicate salt of alkaline earth metal, disilicate salt of alkaline earth metal or mixture thereof. Preferably the intermediate mixture includes alkaline earth metal silicate, alkaline earth metal disilicate or mixtures thereof. Preferably the silicate salt of the alkaline earth metal and/or the disilicate salt of the alkaline earth metal is in amorphous form.

Preferably the alkaline earth metal compound present in the reaction is magnesium sulphate or magnesium chloride, more preferably magnesium sulphate. Preferably when the alkali earth metal compound is a magnesium salt, the in-situ intermediate mixture includes one or more compound selected from the group consisting of magnesium hydroxide, magnesium silicate, magnesium disilicate or mixtures thereof. More preferably the intermediate mixture includes magnesium silicate, magnesium disilicate or mixtures thereof. Preferably the alkali metal silicate is sodium silicate. Preferably the intermediate mixture includes 0 wt.% zeolite.

Preferably the reaction of the alkali metal silicate salt with the alkaline earth metal salt is carried out by heating the aqueous mixture with or without agitation, preferably with agitation in a mixer at a temperature of 20°C to 80°C, more preferably from 70°C to 80°C. The reaction is carried out for a duration of 0.5 minutes to 30 minutes by continuously stirring the aqueous mixture in the slurry handling system. Alternately the alkaline earth metal salt may be pre-dissolved in water and before reacting with the alkali metal silicate in the aqueous mixture.

In addition to the above-mentioned ingredients the intermediate mixture may include some amount of the unreacted alkaline earth metal compound or salt. At the end of this step, in addition to the intermediate mixture the aqueous mixture preferably includes detersive surfactant, preferably any unreacted alkaline earth metal salt and water.

Step (ii): Contacting the intermediate mixture with an organic carboxylic acid:

The next step involves contacting the in-situ formed intermediate mixture with an organic carboxylic acid.

The intermediate mixture reacts with the organic carboxylic acid to form a base mixture having organic carboxylic acid salt of alkaline earth metal. Preferably the organic carboxylic acid is monomeric organic carboxylic acid, still preferably a monomeric organic polycarboxylic acid. Suitable examples of the organic carboxylic acid include but is not limited to formic acid, acetic acid, propionic acid, butyric acid, caprylic acid and lauric acid, stearic acid, linoleic acid, acrylic acid, methacrylic acid, chloroacetic acid, citric acid, lactic acid, glyoxylic acid, acetoacetic acid, oxalic acid, malonic acid, adipic acid, phenylacetic acid, benzoic acid, salicylic acid, glycine, alanine, valine, aspartic acid, glutamic acid, lysine, phenylalanine, nicotinic acid, picolinic acid, fumaric acid, benzoic acid, succinic acid and glycolic acid. Preferably, the organic carboxylic acid is selected from the group citric acid, malic acid, succinic acid, lactic acid, glycolic acid, fumaric acid, tartaric acid, formic acid, and mixtures thereof. More preferably, the organic carboxylic acid is citric acid, lactic acid, and tartaric acid. Most preferably the organic carboxylic acid is citric acid.

The organic carboxylic acid is preferably added in excess. The organic carboxylic acid may react with the intermediate mixture either partly or completely depending upon the time for which the intermediate mixture is allowed to react with the organic carboxylic acid. Typically, when the reaction is allowed to complete, the organic carboxylic acid reacts with the intermediate mixture comprising one or more compounds selected from silicate, disilicate and the hydroxide salt of the alkaline earth metal salt to form a base mixture having the organic carboxylic acid salt of alkaline earth metal. Alternately, the organic carboxylic acid may react partly with the intermediate mixture to form a base mixture having organic carboxylic acid salt of alkaline earth metal along with preferably silicate salt of alkaline earth metal and disilicate salt of the alkaline earth metal. Preferably the organic carboxylic acid salt of alkaline earth metal includes one or more of alkaline earth metal salt organic carboxylic acid, di-alkaline earth metal salt organic carboxylic acid, tri alkaline earth metal salt organic carboxylic acid or mixtures thereof. Preferably the organic carboxylic acid salt of alkaline earth metal is a citric acid salt of magnesium, preferably comprising one or more of magnesium citrate, magnesium dicitrate, magnesium tricitrate or mixtures thereof.

The pH of the base mixture is preferably less than 4, more preferably the pH of the base mixture is from 2 to 3.5. The base mixture preferably has 0 wt.% zeolite. The present inventors have found that base mixture when spray dried directly provides a spray dried detergent particle which does not have prolonged shelf life. They further found that such spray dried detergent particle has an unpleasant odour. Without being bound by any theory, it is believed that the extremely low pH of the base mixture makes the resultant spray-dried detergent particle prone to caking upon extended storage periods.

Step (Hi): Forming an aqueous slurry:

In the next step, an aqueous slurry is formed by adding an amount of alkaline source to the base mixture. The aqueous slurry has a pH of 4 to 8.5. The alkaline source may include any salt which enables the pH to be adjusted to 4 to 8.5. More preferably the alkaline source is selected from the group consisting of alkali metal silicate, alkali metal hydroxide or mixtures thereof. Preferably the alkaline source is selected from the group consisting of sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide or mixtures thereof. Preferably the alkaline source is selected from the group consisting of sodium silicate, sodium hydroxide or mixtures thereof. Preferably the pH of the aqueous slurry is adjusted to range from 4 to 8.5, still preferably from 5 to 8.5.

After the addition of the alkaline source, the aqueous slurry preferably further includes an organic carboxylic acid salt of an alkali metal formed by the reaction of the alkaline source and the organic carboxylic acid added in excess in the previous step. The organic carboxylic acid salt of an alkali metal is preferably an organic carboxylic acid salt in the form of a mono alkali metal, dialkali metal or a trialkali metal organic carboxylic acid salt. Preferably the aqueous slurry has from 1 wt.% to 12 wt.% organic carboxylic acid salt of an alkali metal, preferably a mixture of organic carboxylic acid salt of a dialkali metal and an organic carboxylic acid salt of a trialkali metal, more preferably the organic carboxylic acid salt is a trialkali metal salt. The aqueous slurry preferably includes from 0 wt.% to 3 wt.% organic carboxylic acid salt of a dialkali metal, still preferably from 1 wt.% to 2.1 wt.% of the organic carboxylic acid salt of a dialkali metal. The aqueous slurry preferably includes from 1 wt.% to 12 wt.% organic carboxylic acid salt of a trialkali metal, still preferably from 2 wt.% to 10 wt.%, still more preferably 4 to 10 wt.% of the organic carboxylic acid salt of a trialkali metal. Preferably the organic carboxylic acid salt of an alkali metal includes disodium citrate, trisodium citrate, mono sodium citrate and mixtures thereof.

Filler:

Preferably the aqueous slurry includes a filler selected from the group consisting of sodium sulphate, sodium chloride, calcium carbonate, magnesium carbonate, calcite, dolomite, or mixtures thereof. More preferably the filler is sodium sulphate. The filler acts as a balancing ingredient and can be a neutral inorganic salt or mineral, preferably sodium sulphate or sodium chloride. In one preferred embodiment, the filler is sodium chloride.

The aqueous slurry prepared according to the process of the first aspect of the present invention preferably comprises:

(i) from 2 wt.% to 35 wt.% detersive surfactant;

(ii) from 0.1 wt.% to 4 wt.% organic carboxylic acid salt of alkaline earth metal;

(iii) preferably from 1 wt.% to 12 wt.% organic carboxylic acid salt of alkali metal;

(iv) preferably 0 wt.% to 2.5 wt.% silicate salt and/or disilicate salt of alkaline earth metal;

(v) preferably from 0 wt.% to 1 .5 wt.% unreacted alkaline earth metal salt;

(vi) preferably from 15 wt.% to 70 wt.% filler; and,

(vii) from 20 wt.% to 40 wt.% water.

Preferably the amount of detersive surfactant in the aqueous slurry is not less than 3 wt.%, still preferably not less than 5 wt.%, more preferably not less than 8 wt.%, still more preferably not less than 10 wt.%, but typically not more than 34 wt.%, preferably not more than 32 wt.% or still preferably not more than 30 wt.%.

Preferably the amount of organic carboxylic acid salt of alkaline earth metal in the aqueous slurry is not less than 0.15 wt.%, still preferably not less than 0.2 wt.%, more preferably not less than 0.5 wt.%, still more preferably not less than 0.8 wt.%, further preferably not less than 1 wt.% but typically not more than 3.5 wt.%, preferably not more than 2.5 wt.% or still preferably not more than 2 wt.%.

Preferably the amount of organic carboxylic acid salt of alkali metal in the aqueous slurry is not less than 1 .4 wt.%, still preferably not less than 2 wt.%, more preferably not less than 3.5, still more preferably not less than 4 wt.%, furthermore preferably not less than 4.05 wt.%, but typically not more than 11 .5 wt.%, preferably not more than 11 wt.% or still preferably not more than 10.5 wt.%, more preferably not more than 9.5 wt.%.

Preferably the amount of silicate salt and/or disilicate salt of alkaline earth metal in the aqueous slurry is not less than 0.1 wt.%, still preferably not less than 0.2 wt.%, more preferably not less than 0.25 wt.%, still more preferably not less than 0.3 wt.%, furthermore preferably not less than 0.5, and most preferably not less than 1 wt.% but typically not more than 2.5 wt.%, preferably not more than 2 wt.% or still preferably not more than 1.75 wt.% and most preferably not more than 1 .65 wt.%.

Preferably the amount of unreacted alkaline earth metal salt is not less than 0.1 wt.%, still preferably not less than 0.2 wt.%, more preferably not less than 0.25 wt.%, still more preferably not less than 0.3 wt.%, but typically not more than 1.3 wt.%, preferably not more than 1 .2 wt.% or still preferably not more than 1 wt.%.

Preferably the amount of water is not less than 22 wt.%, still preferably not less than 23 wt.%, more preferably not less than 24 wt.%, still more preferably not less than 25 wt.%, but typically not more than 40 wt.%, preferably not more than 38 wt.% or still preferably not more than 37 wt.% and most preferably not more than 35 wt.%.

Preferably the filler is present in an amount ranging from 15 wt.% to 70 wt.% in the slurry. Preferably the amount of filler is not less than 16 wt.%, still preferably not less than 18wt.%, more preferably not less than 20 wt.%, still more preferably not less than 22 wt.%, but typically not more than 70 wt.%, preferably not more than 68 wt.% or still preferably not more than 65 wt.%.

Additionally, one or more of optional ingredients may be present in the aqueous slurry. The optional ingredients may include but it not limited to polymer, optical brighteners which is preferably selected from fluorescers, colourants, hydrotropes, shading dye, pigments, or mixtures thereof and antifoams.

Optionally the aqueous slurry includes silica. Preferably the silica is present in an amount ranging from 0.1 to 3.5 wt.%, still preferably from 0.2 to 2 wt.%. The silica may be either performed or generated in-situ. Preferably the aqueous slurry has less than 2 wt.% alkali metal silicate, still preferably less than 1 wt.%, further preferably 0 wt.% alkali metal silicate. The aqueous slurry preferably has 0 wt.% to 2 wt.% alkali metal silicate.

Preferably the aqueous slurry has less than 2 wt.% carbonate builder, still preferably less than 1 wt.%, further preferably 0 wt.% carbonate builder. Preferably the aqueous slurry has 0 wt.% to 2 wt.% carbonate builder. Examples of the carbonate builder salt includes alkaline earth metal and alkali metal carbonates or mixtures thereof. Typically, the alkali metal carbonates are sodium and/or potassium carbonate of which sodium carbonate is most preferred. Alkali metal carbonate according to the invention refers to carbonates, bicarbonates, sesquicarbonates or mixtures thereof. Preferably alkali metal carbonate comprises of sodium carbonate.

Preferably the aqueous slurry has less than 2 wt.% inorganic phosphate builder, still preferably less than 1 wt.%, further preferably 0 wt.% inorganic phosphate builder. Preferably the aqueous slurry has less than 0 wt.% to 2 wt.% inorganic phosphate builder. Examples of inorganic phosphate builder includes sodium orthophosphate, pyrophosphate and tripolyphosphate.

Preferably the aqueous slurry has less than 2 wt.% zeolite builder, still preferably less than 1 wt.%, further preferably 0 wt.% zeolite builder. Preferably the aqueous slurry has 0 wt.% to 2 wt.% zeolite builder. Examples of the zeolite builder includes zeolite A, zeolite 4A, aluminium zeolite P (zeolite MAP) described and claimed in EP 384 070A (Unilever). Zeolite MAP is an alkali metal aluminosilicate of the P type having a silicon to aluminium ratio not exceeding 1.33, preferably not exceeding 1.15, and more preferably not exceeding 1 .07.

The aqueous slurry may optionally include a polymer. Suitable polymers include carboxylate polymers, soil release polymers, anti-redeposition polymers, cellulosic polymers, care polymers and any combination thereof. Preferably the polymer is a carboxylate polymer. The carboxylate polymer may be a homopolymer or a copolymer. Preferably the copolymer is a maleate/acrylate random copolymer. Preferably the maleate/acrylate random copolymer has a molecular weight ranging from 1000 Da to 100,000 Da, more preferably from 30,000 Da to 100,000 Da or still preferably from 50,000 Da to 100,000 Da, or from 60,000 Da to 80,000 Da. Preferably the homopolymer is a polyacrylate. Preferably the polyacrylate homopolymers has a molecular weight ranging from 4,000 Da to 9,000 Da. The aqueous slurry may preferably include powder structuring agents. Non-limiting examples of the powder structuring agents includes a fatty acid (or fatty acid soap), a sugar, an acrylate or acrylate/maleate polymer, the powder structuring agent is present in an amount of 1 wt.% to 5 wt.% in the aqueous slurry.

The aqueous slurry preferably includes less than 5 wt.% organic carboxylic acid, still preferably less than 4 wt.%, further preferably less than 3 wt.%, more preferably less than 1 wt.%, still more preferably the aqueous slurry has 0 wt.% organic carboxylic acid.

Further optional ingredients may be added to the aqueous slurry which includes but are not limited to, any one or more of the following: soap, sequestrants, calcium chloride, other inorganic salts, fluorescers, foam controllers, foam boosters, dyes, anti-redeposition agents, colourants, shading dyes, hydrotropes, viscosity modifiers, dispersants and combinations thereof. Non-limiting examples of hydrotropes are preferably selected from the group consisting of sodium toluene sulphonate, sodium cumene sulphonate, sodium xylene sulphonate or mixtures thereof. Preferably the anti-redeposition agents are sodium carboxyl methyl cellulose. Preferably these optional ingredients must have the ability to withstand the temperature conditions in a spray-drying process. Preferably a filler may be added to the aqueous slurry before spray-drying.

Step (iv): Forming the spray-dried detergent particle

In the next step, the aqueous slurry is spray dried to form a spray-dried detergent particle.

The spray-drying is carried out using any of the conventional spray drying system known in the art. Preferably in the spray drying system the aqueous slurry is transferred through a pipe system to a pump system consisting of one or more pump and then further to a spray nozzle through which the slurry is released under pressure into a drying tower.

A typical spray-drying process involves the step of transferring the aqueous slurry through a pipe system leading to a first pump and then through a second pump and from a second pump to a plurality of spray nozzles. The first pump is typically a low-pressure pump, such as a pump that can generate a pressure of from 1x10⁵ Nm^-2 to 1x10⁶ Nm^-2, which ensures proper flooding of the second pump. Typically, the second pump is a high-pressure pump, such as a pump that can generate a pressure ranging from 2x10⁶Nm^-2 to 2x10⁷Nrrr². Optionally, the aqueous slurry may be transferred through bolt catchers, magnetic filters, lump breakers, disintegrators such as the Ritz Mill, during the transfer of the aqueous slurry through the pipe system downstream the pump system or the mixer in which the aqueous slurry is formed. The disintegrator is preferably positioned between the pumps. The flow rate of the aqueous slurry along the pipes is typically in the range from 800 Kg/hour to more than 75,000 Kg/hour.

Optionally, the spray drying system may include a deaeration system. The deaeration system is preferably a vacuum assisted de-aerator, which is preferably fed by a transfer pump. The deaeration system remove air bubbles formed during the slurry preparation, thus increasing the bulk density of the spray-dried detergent particle. De-aeration of the slurry may also be carried out by other mechanical means or chemical de-aeration means using antifoams or de-foamers.

Optionally, air injection system may be provided along the pipe system. The air injection system may be provided before or after the pump system. The air injection includes air flow and pressure controls, static mixer, pulsation dampener and compressor set which can aerate the slurry to get a lower bulk density for the spray dried particle. The gas injected into the slurry may be nitrogen, carbon dioxide, or simply atmospheric air introduced under a pressure higher than the pressure of the aqueous slurry maintained in the pipe system. A typical spray drying system can optionally include both the de-aeration system and air injection system to optimize the desired bulk density of the spray dried detergent particle.

Typical spray drying tower for detergent applications are counter-current spray drying tower. To obtain the desired moisture content and the particle size distribution the inlet hot air or hot steam temperature introduced into the spray drying tower is the range from 250°C to 500°C depending on the evaporation capacity and sizing of the tower. Preferably the tower exhaust air temperature can range from 60°C to 200°C, more preferably 80°C to 200°C, still more preferably 80°C to 100°C depending on the loading of the tower. The aqueous slurry introduced into the spray nozzle of the spray drying tower is preferably at a temperature ranging from 60°C to 95°C. The spray drying tower may be a co-current spray drying tower but they are less common. The spray-dried detergent particle existing the tower is maintained at a temperature less than 150°C, still preferably less than 100°C. The spray-drying is preferably conducted in the spray drying zone under a negative pressure of at least 50 Nm^-2, still preferably the negative pressure is from 50 Nrrr²to 600 NOT² Preferably, the vacuum conditions are achieved by controlling the speed setting of the dampener of either or both the inlet and the outlet air fan. The spray-dried detergent particle collected at the bottom of the tower may be subjected to cooling and conditioning by using an air lift or other similar process known to a person skilled in the art for cooling and conditioning spray-dried particle. The spray-dried particle collected from the bottom of the spray-drying tower is preferably mixed with a flow aid chosen from zeolite, silica, precipitated calcite sodium carbonate, salt, or similar fine mineral particles selected from the group consisting of dolomite, calcite or mixtures thereof, just before being air-lifted. Preferably, the spray-dried detergent particle is subject to particle size classification to remove oversize material (> 2 mm typically) to provide a spray dried detergent particle which is free flowing. Preferably the fine material (< 100 microns typically) is elutriated with the exhaust air in the spray drying tower and captured and recycled back into the system via the dry cyclone, wet cyclone or bag filter system.

Spray-dried detergent particle:

According to a second aspect of the present invention disclosed is a spray-dried detergent particle obtainable by the process of the first aspect. Spray-dried detergent particle formed from the process of the first aspect of the present invention preferably has a pH of 4 or more, preferably a pH ranging from 4 to 8.5, more preferably 5 to 8.5, still preferably 6 to 8.5 when measured using a 1 wt.% solution with distilled water at 25°C. The spray-dried detergent particle is generally referred to as the base powder. This base powder may be used as a fully formulated laundry detergent composition. Alternately a percentage of the base powder may be mixed with other post dosed ingredients to form the fully formulated laundry detergent composition.

Preferably the spray-dried detergent particle includes:

(i) from 3 wt.% to 50 wt.% detersive surfactant; preferably anionic detersive surfactant;

(ii) from 0.2 wt.% to 6 wt.% organic carboxylic acid salt of alkaline earth metal;

(iii) preferably from 2 wt.% to 20 wt.% organic carboxylic acid salt of alkali metal;

(iv) preferably from 0 wt.% to 4 wt.% silicate and/or disilicate salt of alkaline earth metal;

(v) preferably from 0 wt.% to 2 wt.% unreacted alkaline earth metal salt;

(vi) preferably 25 wt.% to 88 wt.% filler; and,

(vii) preferably from 1 wt.% to 3.5 wt.% moisture content.

Preferably the amount of detersive surfactant in the spray-dried detergent particle is not less than 3 wt.%, still preferably not less than 5 wt.%, more preferably not less than 8 wt.%, still more preferably not less than 10 wt.%, but typically not more than 40 wt.%, preferably not more than 35 wt.% or still preferably not more than 30 wt.%.

Preferably the amount of organic carboxylic acid salt of alkaline earth metal in the spray-dried detergent particle is not less than 0.25 wt.%, still preferably not less than 1 wt.%, more preferably not less than 1 .5 wt.%, still more preferably not less than 2 wt.%, but typically not more than 5 wt.%, preferably not more than 4 wt.% or still preferably not more than 3 wt.%.

Preferably the amount of organic carboxylic acid salt of alkali metal in the spray-dried detergent particle is not less than 2.5 wt.%, still preferably not less than 3.5 wt.%, more preferably not less than 5, still more preferably not less than 5.5 wt.%, furthermore preferably not less than 8 wt.%, but typically not more than 18 wt.%, preferably not more than 15 wt.% or still preferably not more than 12 wt.%, more preferably not more than 10 wt.%.

Preferably the amount of silicate salt and/or disilicate salt of alkaline earth metal in the spray- dried detergent particle is not less than 0.1 wt.%, still preferably not less than 0.2 wt.%, more preferably not less than 0.25 wt.%, still more preferably not less than 0.3 wt.%, but typically not more than 3.8 wt.%, preferably not more than 3 wt.% or still preferably not more than 2.5 wt.%.

Preferably the amount of unreacted alkaline earth metal salt in the spray-dried detergent particle is not less than 0.1 wt.%, still preferably not less than 0.2 wt.%, more preferably not less than 0.25 wt.%, still more preferably not less than 0.3 wt.%, but typically not more than 1 .8 wt.%, preferably not more than 1 .7 wt.% or still preferably not more than 1 .65 wt.%.

Preferably the amount of moisture content present in the spray-dried particle is not less than 2 wt.%, still preferably not less than 2.25 wt.%, more preferably not less than 2.5 wt.%, still more preferably not less than 2.75 wt.%, but typically not more than 3.5 wt.%, preferably not more than 3.25 wt.% or still preferably not more than 3.0 wt.%.

Preferably the filler is present in an amount ranging from 25 wt.% to 88 wt.% in the spray-dried detergent particle. Preferably the amount of filler is not less than 26 wt.%, still preferably not less than 30 wt.%, more preferably not less than 32 wt.%, still more preferably not less than 35 wt.%, but typically not more than 87 wt.%, preferably not more than 75 wt.% or still preferably not more than 65 wt.%, still more preferably not more than 50 wt.%. The filler acts as a balancing ingredient and can be a neutral inorganic salt or mineral, preferably sodium sulphate or sodium chloride. In one preferred embodiment, the filler is sodium chloride. In another preferred embodiment the filler is a mixture of sodium chloride and sodium sulphate.

Additionally, one or more of optional ingredients may be present in the spray-dried detergent particle. The optional ingredients may include but it not limited to polymer, hydrotropes, optical brighteners which is preferably selected from fluorescers, colourants, shading dye, pigments, or mixtures thereof and antifoam.

Preferably the spray-dried detergent particle includes silica. Preferably the silica is present in an amount ranging from 0.2 wt.% to 5 wt.%, still preferably from 0.2 wt.% to 3.5 wt.%, further preferably from 0.2 wt.% to 3 wt.%, still more preferably 0.5 wt.% to 2.5 wt.% in the spray-dried detergent particle. The silica may be either performed or generated in-situ.

Preferably the spray-dried detergent particle has less than 2 wt.% alkali metal silicate, still preferably less than 1 wt.%, further preferably 0 wt.% alkali metal silicate.

Preferably the spray-dried detergent particle has less than 2 wt.% carbonate builder, still preferably less than 1 wt.%, further preferably 0 wt.% carbonate builder. Examples of the carbonate builder salt includes alkaline earth metal and alkali metal carbonates or mixtures thereof. Typically, the alkali metal carbonates are sodium and/or potassium carbonate of which sodium carbonate is mostly preferred. Alkali metal carbonate according to the invention refers to carbonates, bicarbonates, sesquicarbonates or mixtures thereof.

Preferably the spray-dried detergent particle has less than 2 wt.% inorganic phosphate builder, still preferably less than 1 wt.%, further preferably 0 wt.% inorganic phosphate builder.

Examples of inorganic phosphate builder includes sodium orthophosphate, pyrophosphate and tripolyphosphate.

Optionally, the spray-dried detergent particle includes from 0 wt.% to 5 wt.% polymer, still more preferably from 0.5 to 5 wt.%, still more preferably 0.5 wt.% to 4 wt.% polymer. Preferably the polymer is a carboxylate polymer. Still preferably a polyacrylate polymer, still preferably a copolymer of acrylic acid or methacrylic acid with maleic acid. The spray dried detergent particle may include further polymer selected from antiredeposition polymer, soil release polymer, structuring polymer or mixtures thereof. Preferably the polymer is a polymeric carboxylate, preferably polyacrylate or a copolymer of acrylic acid and maleic acid. However other polymers may also be suitable such as polyamines (including the ethoxylated variants thereof), polyethylene glycol and polyesters. Polymeric soil suspending aids and polymeric soil release agents are particularly suitable. Preferably the anti-redeposition agents are sodium carboxyl methyl cellulose.

Preferably the spray-dried detergent particle has less than 2 wt.% zeolite builder, still preferably less than 1 wt.%, further preferably 0 wt.% zeolite builder. Examples of the zeolite builder includes zeolite A, zeolite 4A, aluminium zeolite P (zeolite MAP) described and claimed in EP 384 070A (Unilever). Zeolite MAP is an alkali metal aluminosilicate of the P type having a silicon to aluminium ratio not exceeding 1 .33, preferably not exceeding 1 .15, and more preferably not exceeding 1 .07.

The spray dried detergent particle may be optionally contacted with a non-ionic surfactant, a fatty acid or combinations thereof. The non-ionic surfactant and the fatty acid is in liquid form. In addition to the non-ionic surfactant and the fatty acid in liquid form any other liquid laundry ingredient which is not suitable to be added via slurry or tower, may be added by spraying the liquid onto the spray-dried detergent particle. The sprayed liquid is soaked onto the hot base powder coming out of the tower. The spraying may be carried out while the spray-dried detergent particle passes through an inline low shear rotary drum, or an online densification kit which is typically a plough shear mixer.

After spray-drying, the collected spray-dried particle is preferably layered with a layering agent. Preferably the layering agent is selected from the group consisting of zeolite, silica, precipitated calcite, sodium carbonate, salt, calcite, clay, dolomite or mixtures thereof. Preferably the zeolite is synthetically prepared. Preferably the level of the layering agent added to the spray-dried detergent particle is from 0 wt.% to 10 wt.% of the surfactant content present in the spray-dried detergent particle. Preferably the layering agent is added to give additional anticaking benefit.

Preferably the spray-dried detergent particle has a bulk density of less than 550g/L. Preferably the spray-dried detergent particle has a weight average particle size ranging from 300 micrometres to 600 micrometres.

The pH of the spray dried detergent particle is preferably from 4 to 8.5, more preferably above 7, still preferably from 7 to 8. The spray-dried laundry detergent particle preferably comprises from 3 wt.% to 50 wt.% anionic surfactants, which is preferably a C10 to C20 linear alkyl benzene sulphonate and which is substantially neutralized with little or no acid residues.

The spray-dried laundry detergent particle is typically post dosed with ingredients that are incompatible with the spray-drying process conditions to form a fully formulated laundry detergent composition. These components may be incompatible for many reasons including heat sensitivity, pH sensitivity or degradation in aqueous systems.

Laundry detergent composition

According to a further aspect of the present invention, disclosed is a laundry detergent composition having the spray-dried laundry detergent particle of the first aspect of the invention. Detergent compositions of low to moderate bulk density may be prepared by spray-drying the aqueous slurry to form a spray-dried particle and optionally postdosing (dry-mixing) further ingredients. Alternately "compact" detergent compositions may be prepared by further mixing the spray dried laundry detergent particle prepared according to the present invention in a highspeed mixer/granulator, or other non-tower processes. The spray dried detergent particle may also be used for preparing a tablet composition by compacting powders, especially "concentrated" powders using a known tableting process. Further, the spray dried detergent particle may be used for preparing an unit dose product wherein the spray-dried detergent particle is enclosed in a pouch, preferably a water-soluble pouch, more preferably a water- soluble pouch comprising a film forming polymer selected from polyvinyl alcohol, polyvinylpyrrolidone and other known film forming polymer.

The spray-dried detergent particle (generally also referred to as a base powder) is preferably formulated into a finished laundry detergent composition by dry mixing heat sensitive ingredients into the base powder. In addition to heat sensitive ingredients some amount of alkalinity may be added back into the base powder by addition of alkaline ingredients, additionally other acidic or neutral may also be added to formulate the finished laundry detergent composition.

The spray-dried detergent particle may be used as a fully formulated laundry detergent composition or may be additionally combined with other optional ingredients to form a fully formulated laundry detergent composition. Non-limiting examples of the optional post-dosed benefit ingredients includes but is not limited to enzymes, anti-redeposition polymers, perfumes, additional surfactant selected from amphoteric surfactant, zwitterionic surfactant, cationic surfactant and non-ionic surfactant, optical brighteners, antifoaming agent, foam boosters, fabric softeners such as smectite clays, amine softeners and cationic softeners; bleach and bleach activators; dyes or pigments, fillers, fluorescers, salts, soil release polymers, dye transfer inhibitors. These optional ingredients are well known to be used in a laundry detergent composition and added preferably by post-dosing.

The laundry detergent composition includes from 5 wt.% to 100 wt.% spray-dried detergent particle obtainable according to the first aspect of the present invention. More preferably from 20 wt.% to 95 wt.%, still preferably from 30 wt.% to 95 wt.% of the spray-dried detergent particle obtainable according to the first aspect of the present invention.

Non-limiting examples of the post-dosed polymers include cleaning polymers, antiredeposition polymers, soil release polymers structuring polymers. Some examples include PET-PEOT polymer (Repel-o-Tex® SF2 ex. Solvay), copolymer of acrylic acid and maleic acid (Sokalan CP5 ex. BASF). Preferably anti-redeposition agents are sodium carboxyl methyl cellulose.

Fluorescers

Suitable fluorescent brighteners include dis-styryl biphenyl compounds example Tinopal® CBS- X, di-amino stilbene di-sulfonic acid compounds, e.g. Tinopal® DMS pure Xtra and Blankophor® HRH, and Pyrazoline compounds, e.g. Blankophor® SN, and coumarin compounds, e.g. Tinopal® SWN. Preferred brighteners are: sodium 2 (4-styry)-3-sulfophenyl)- 2H-napthol(1 ,2-d]triazole, disodium 4, 4’bis{[4-anilino-6-(N methyl-N-2 hydroxyethyl)amino 1 ,3,5- triazin-2-yl)]amino]stilbene-2-2' disulfonate, disodium 4,4’bis([(4-anilino-6-morpholino-l,3,5- triazin-2-yl)]amino} stilbene-2-2'disulfonate, and disodium 4,4’- bis(2-sulfostyryl)biphenyl. A suitable fluorescent brightener is S C.l. Fluorescent Brightener 260, which may be used in its beta or alpha crystalline forms, or a mixture of these forms.

Enzymes:

The composition of the present invention preferably includes an enzyme. It may preferably include one or more enzymes. Preferred examples of the enzymes include those which provide cleaning performance and/or fabric care benefits.

Examples of suitable enzymes include, but are not limited to, hemicellulases, peroxidases, proteases, cellulases, xylanases, lipases, xyloglucanase, phospholipases, esterases, cutinases, pectinases, mannanases, pectate lyases, keratinases, reductases, oxidases, phenoloxidases, lipoxygenases, ligninases, pullulanases, tannases, pentosanases, malanases, G-glucanases, arabinosidases, hyaluronidase, chondroitinase, laccase, and amylases, or mixtures thereof. A typical combination is an enzyme cocktail that may comprise, for example, a protease and lipase in conjunction with one or more of amylase, mannanase and cellulase. When present in a detergent composition, the enzymes may be present at levels from about 0.00001% to about 2%, from about 0.0001% to about 1% or from 0.001% to about 0.5% enzyme protein by weight of the detergent composition.

Packaging and dosing:

According to another aspect of the present invention, disclosed is a packaged article comprising a flexible container enclosing a laundry detergent composition having a spray dried detergent particle prepared according to the first aspect of the present invention. The flexible container is preferably made from a packaging material suitable for packaging laundry detergent composition the packaging material includes but is not limited to polyolefin film, laminates, paper based films or laminates, multilayered structures including two or more flexible structures and other materials known to a person skilled in the art. Typically the flexible container includes polyethylene films having polymer selected from HDPE, LLDPE, mLLDPE, LDPE or combination thereof. The flexible films may be made of monomaterial or combination of different materials. Preferably the flexible packaging container is a flexible pouch or a bag. It is preferably selected from a material which is biodegradable, compostable, recyclable or combinations of those. The flexible container may preferably include a measurement means which may be supplied with the package either as a part of the closure of the container or as an integrated system or a separate dosing measure may be provided along with the package.

In yet another embodiment the laundry detergent composition comprising the spray dried detergent particle of the present invention may be packaged as unit dose product enclosed within a polymeric film, wherein the polymeric film is water soluble or disintegrates upon addition to the wash water. Alternatively, the spray-dried detergent particle or a laundry detergent composition including the spray-dried detergent particle of the invention may be supplied in multidose plastics packs with a top or bottom closure.

According to another aspect of the present invention, provided is a method of laundering fabric using a spray dried detergent particle or a laundry composition comprising a spray dried detergent particle according to the present invention which method involves the step of diluting an amount of the laundry detergent composition with water to obtain a wash liquor followed by the step of washing fabrics with the wash liquor so formed. In automatic washing machines a measured amount of detergent composition (dose) is typically put into a dispenser and from there it is flushed into the machine by the water flowing into the machine, thereby forming the wash liquor. From 5 up to about 65 litres of water may be used to form the wash liquor depending on the machine configuration. The dose of detergent composition may be adjusted accordingly to give appropriate wash liquor concentration. The dilution step preferably provides a wash liquor having from 3 to 20 g/wash of detersive surfactants (as are further defined above).

The product obtainable by a process according to the present invention has different product characteristics due to its process of manufacture. The product has good physical properties, such as good cake strength and good flowability. The product also has good dispensing properties, dissolution, and minimal fabric residue deposition. This is due to the in-situ formation of organic carboxylic acid of alkaline earth metal.

Examples

Example 1 : Process for preparing the spray-dried detergent particle according to the present invention

A spray-dried detergent particle according to the present invention was prepared by adding water, alkaline source (sodium hydroxide, 50% active content) and acid form of the anionic surfactant (LAS acid, 97% active content) to a mixing unit to form sodium LAS in-situ. The ingredients were mixed well and while the agitation was continued the remaining ingredients were added in the order of addition as mentioned in the Table 1 below. During the mixing the temperature in the mixing unit was maintained with steam at 80°C +/-2°C. Firstly the intermediate mixture was prepared by reacting the magnesium sulphate (alkaline earth metal salt) and sodium silicate with a SiC>2:Na2O ratio of 2.4 (alkali metal silicate salt 47% active content) followed by the addition of citric acid (organic carboxylic acid). With the addition of citric acid, the aqueous mixture pH is brought down to 3. Next the citric acid reacts with the intermediate mixture to form magnesium citrate in the base mixture. Thereafter the pH of the base mixture was raised in two steps by first adding an aqueous solution having 50% concentration sodium hydroxide and then sodium silicate was added to form an aqueous slurry. The final pH of the aqueous slurry was maintained at 8.5. Table 1

The composition of the prepared aqueous slurry was as given below in Table 1 A Table 1A

Next the above aqueous detergent slurry was spray dried in a counter-current spray drying tower. The aqueous detergent slurry was heated to 80°C and pumped under pressure (7.5x106 Nm-²), into a counter current spray-drying tower with an air inlet temperature ranging from between 250°C to 330°C. The inlet fan was set to provide a tower inlet airflow of 187,500 kgh^-1. The exhaust fan was controlled to create a negative pressure in the tower of -200 Nm- ² (typically the outlet air flow rate through the exhaust fan is between 220,000 kgh^-1 to 240,000 kgh^-1, this includes the evaporated water from the slurry). The aqueous slurry was atomised into the tower where the atomised slurry was dried to produce a spray-dried detergent particle, which was then cooled and sieved to remove oversize material (> 1 ,8mm). The spray dried detergent particle obtained was found to be free-flowing. Fine material (<0.175mm) was elutriated along with the exhaust air coming out of the spray-drying tower and was later collected in a post tower containment system. The spray-dried detergent particle had a moisture content of 2.0 wt.%, a bulk density of 350g/L and a particle size distribution such that greater than 90 wt.% of the spray-dried detergent particle has a particle size ranging from 175 to 710 micrometres. The temperature of the spray-dried detergent particle exiting the tower has a temperature of below 150°C. The composition of the spray-dried detergent particle obtained by spray-drying the aqueous detergent slurry is given below.

Table 2

The spray-dried particle was collected and characterized for the storage behaviour.

Example 2: Evaluation of the storage properties of the spray-dried detergent particle Spray-dried detergent particle according to the present invention (Ex 1) was evaluated for the powder properties using the compression test method. The caking tendency of the spray dried particle was measured and compared with the comparative examples. Compression Test Method: This test evaluates the tendency of the powder towards caking. A split cylinder with a polished internal surface was positioned on a firm base to form a hollow cylindrical mould with a diameter of 9 centimetres. Spray dried detergent particle to be tested was filled and levelled. A plastic disc was placed on the powder mass. A weight of 12 kilograms was slowly placed on the plastic disc in such a way that the weight was uniformly applied on the powder mass in the mould allowing it to compact. After 2 minutes the weight was removed, and the cylindrical mould was opened slowly without disturbing the compacted cake. Incremental weights of 200 grams were added at an interval of 10 seconds till the compacted cake collapses. Total vertical load required to collapse the formed cake was noted and expressed in Kg and provides an indication of the caking tendency of the particle. Higher the value, greater is the caking tendency of the spray-dried detergent particle under evaluation. For the present evaluation, values lower than 1 Kg was considered good and any value above 2 Kilograms is classified as cohesive and the spray dried detergent particle is considered to have high caking tendency.

Example 2A: Evaluation of the storage behaviour of a spray dried detergent particle according to the present invention and comparative examples with higher pH

The storage behaviour of the spray dried detergent particle according to the present invention was evaluated along with comparative spray dried detergent particle having higher pH. In a control spray dried detergent particle (Control), both silicate and carbonate were added at conventional levels for providing good powder structuring properties. In a first comparative example (Ex A), high levels of carbonate were used for structuring, but the spray dried particle had no silicate. In a second comparative example (Ex B), carbonate levels of Ex A were maintained, and a low amount of silicate was also added. In a third comparative example (Ex C), silicate was used for providing the structuring and no carbonate was used.

The prepared slurries were processed, and spray-dried detergent particle were prepared under similar conditions as described in Example 1 .

Next the collected spray-dried particle was packed and sealed in packs with a water vapour transmission <5 gram/m²/day. The packs were then stored for 8 weeks and 12 weeks at a temperature of 45°C and relative humidity of 80RH. The caking tendency of the spray-dried particle was determined by performing the compression test on the spray-dried particle at different time intervals which were :- once immediately after collecting the spray-dried particle (t=0, freshly prepared powder), then after 8 weeks and another at 12 weeks. The results were recorded and is provided in table 3 below.

Table 3

The data in table 3 shows that the spray-dried detergent particle according to the present invention having no carbonate and no silicate and having an in-situ formed magnesium citrate provided good storage properties and the spray-dried particle was free flowing even after 12 weeks and had slightly better powder properties than the control wherein the control powder has higher pH and high levels of carbonate and silicate. In contrast, the comparative Ex A with high levels of carbonate but no silicate was not processable due to slurry thickening, while Ex B and Ex C did not show good storage properties.

From the above results it was found that even when having higher levels of the detersive surfactant (30 wt.% in the Ex 1 as compared to 25 wt.% in control and comparative examples), the spray-dried particle prepared according to the present invention had good powder properties and fared better, the spray dried particle according to the invention was free flowing when freshly prepared (t = 0) as well as on prolonged storage.

Example 2B: Evaluation of the storage behaviour of a spray dried detergent particle according to the present invention and comparative examples with alternate ingredients for providing good powder properties The storage behaviour of the spray dried detergent particle according to the present invention was evaluated along with comparative spray dried detergent particle having alternate ingredients for providing good powder properties. In a first comparative example (Ex D), preformed silica was added for structuring. In a second comparative example (Ex E), in-situ formed sodium citrate was used for structuring along with pre-formed added silica. In-situ sodium citrate was formed by reacting citric acid with sodium hydroxide in the slurry which was thereafter spray-dried. In a third comparative example (Ex F), silica and sodium citrate which were formed in-situ was used for improving the powder properties. The silica was formed by reacting citric acid with sodium silicate during slurry making. In all the comparative example and the invention, the active was Na LAS made in-situ during the slurry making by reacting Las acid with sodium hydroxide as per stoichiometry.

The slurries prepared were processed and spray-dried under similar conditions as described in Example 1 .

Next the collected spray-dried particles were packed and sealed in packs having a water vapour transmission <5 gram/m²/day. The packs were then stored for 8 weeks and 12 weeks at a temperature of 45°C and relative humidity of 80RH. The caking tendency of the spray-dried particle was determined by performing the compression test on the spray-dried particle, at different time intervals that is - immediately after collecting the (t=0), after 8 weeks and 12 weeks.

The results were recorded and is provided in table 4 below.

Table 4

* silica in Ex D and Ex E is preformed and added to the slurry before spray drying. All other ingredients mentioned namely Na citrate, Mg citrate and silica in the different examples are in- situ formed.

The data in table 4 demonstrates that the spray-dried detergent particle according to the present invention (Ex 1) having no carbonate and no silicate and structured using magnesium citrate provided good storage properties and the powder was free flowing even after 12 weeks. In contrast, other comparative powders (Ex E and Ex F) having in-situ formed ingredients for providing good powder properties (silica and/or sodium citrate) showed higher propensity to cake over extended storage time (12 weeks for Ex E and 8 weeks for Ex F). It was also found that Ex D having added silica had a higher propensity to cake even immediately after spraydrying.

From these results it is clear that the powder properties of the spray dried particle made according to the present invention (Ex 1) is better in terms of storage behaviour and the spray- dried particle has good powder properties and is free flowing both measured after freshly prepared as well as post prolonged storage where the spray-dried particle had a detersive active content of 30 wt.% and sulphate as a preferred filler.

Claims

1 . A process for preparing a spray-dried laundry detergent particle comprising the steps of:

(ii) contacting the intermediate mixture having one or more compound selected from the group consisting of alkaline earth metal hydroxide, alkaline earth metal silicate, alkaline earth metal disilicate or mixtures thereof with an organic carboxylic acid in the aqueous mixture to form a base mixture comprising organic carboxylic acid salt of alkaline earth metal;

(iii) adding an amount of alkaline source to the base mixture to provide an aqueous slurry having a pH ranging from 4 to 8.5, wherein the aqueous slurry comprises an organic carboxylic acid salt of alkaline earth metal, and a detersive surfactant;

(iv) spray-drying the aqueous slurry to form a spray-dried detergent particle.

2. A process according to claim 1 wherein the aqueous slurry comprises a disilicate or silicate salt of alkaline earth metal.

3. A process according to claim 1 or 2 wherein the alkaline earth metal compound is selected from the group consisting of magnesium sulphate, magnesium chloride or mixtures thereof.

4. A process according to claim 1 to 3 wherein the alkali metal silicate salt is sodium silicate.

5. A process according to any one of the preceding claims wherein the aqueous slurry further comprises an in-situ formed organic carboxylic acid salt of alkali metal formed by reacting the organic carboxylic acid with the alkaline source.

6. A process according to claim any one of the preceding claims wherein the alkaline source is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium silicate or mixtures thereof. A process according to any one of the preceding claims wherein the organic carboxylic acid is a monomeric organic polycarboxylic acid, preferably citric acid. A process according to any one of the preceding claims wherein the aqueous slurry comprises not more than 2 wt.% alkali metal silicate. A process according to any one of the preceding claims wherein the detersive surfactant is an anionic surfactant preferably selected from the group consisting of alkyl benzene sulphonate, alkyl ether sulphate, alkyl sulfate or mixtures thereof. A process according to claim 9 wherein the alkyl benzene sulphonate is a linear alkylbenzene sulphonate surfactant having a C10 to C alkyl group. A process according to any one of the preceding claims wherein the organic carboxylic acid salt of alkaline earth metal is a citric acid salt of magnesium, preferably comprising one or more of magnesium citrate, magnesium dicitrate, magnesium tricitrate or mixtures thereof. A process according to any one of the preceding claims wherein the aqueous slurry comprises a carboxylate polymer. A process according to any one of the preceding claims wherein aqueous slurry comprises:

(i) from 2 wt.% to 35 wt.% detersive surfactant;

(iv) preferably from 0 wt.% to 2.5 wt.% silicate salt and/or disilicate of alkaline earth metal;

(v) preferably from 0 wt.% to 1 .5 wt.% unreacted alkaline earth metal salt;

(vi) preferably from 15 wt.% to 70 wt.% filler; and,

(vii) from 20 wt.% to 40 wt.% water. A spray-dried detergent particle obtainable according to any one of the preceding claims comprising:

(i) from 3 wt.% to 50 wt.% detersive surfactant;

(ii) from 0.2 wt.% to 6 wt.% organic carboxylic acid salt of alkaline earth metal; (iii) preferably from 2 wt.% to 20 wt.% organic carboxylic acid salt of alkali metal;

(v) preferably from 0 wt.% to 2 wt.% unreacted alkaline earth metal salt;

(vi) preferably 25 wt.% to 88 wt.% filler; and,

(vii) preferably from 1 wt.% to 3.5 wt.% moisture content. A laundry detergent composition comprising 5 wt.% to 100 wt.% spray dried particle according to claim 14.