Field of the Invention

The present invention relates to a spray-dried laundry detergent particle comprising acrylic acid maleic acid copolymer and a laundry composition comprising the spray-dried detergent particle.

Background of the Invention

Laundry detergent powders are typically produced by a spray-drying process. Typically, detergent ingredients are mixed to form an aqueous detergent slurry in a mixer. This slurry is then transferred through a series of pumps and holding vessels and then dried in a spray-drying tower to form spray-dried laundry detergent particles. The spray-dried particle is also called base powder to which other ingredients such as polymers, enzymes and fragrances may be added to form a fully formulated laundry detergent composition.

The slurry containing the alkali metal carbonate may form lumps which poses a problem for further processing and spray-drying. The problem of lumping is pronounced when the alkali metal carbonate includes particles which have a weight average particle size of less than 75 micrometers. Particularly when the alkali metal carbonate is from a natural source. The alkali metal carbon from natural source have higher bulk density as compared to the alkali metal carbonate which is synthetically prepared. Lumps in the slurry causes slurry flow issues which in turn affects the properties of the final spray-dried detergent particle.

To reduce the lump formation in slurries, polymeric dispersants have been known to be added to the crutcher mix. Examples of such additives are polycarboxylate polymers such as acrylic polymers and acrylic/maleic copolymers. These polycarboxylate polymers are typically added based on the amount of the carbonate and detergent levels present in the detergent composition. The addition of polycarboxylates results in the dispersion of solids in the crutcher and thereby reduces the agglomerated carbonate lumps formed in the slurry.

Polymeric polycarboxylates such as polyacrylates are known to act as effective sequestering and dispersing agents as well as crystal growth inhibitors. These polymers show the benefit of sequestering and dispersing agents at certain levels. However, such polycarboxylates have limited biodegradability which presents an environmental problem if they are used in relatively large amount. It is therefore desired to a provide a weight efficient polymer which can replace the existing nonbiodegradable polymer.

It is an object of the present invention to provide a spray-dried detergent particle which is easily processable to provide spray-dried particle with desired powder properties.

It is yet another object of the present invention to provide a spray-dried detergent particle which provides good slurry properties which thereby provides free-flowing properties to the spray- dried detergent particle.

Summary of the Invention

The present inventors have found that when a spray-dried detergent particle includes a copolymer of acrylic acid and the maleic acid having a weight ratio between the acrylic acid segment and the maleic acid segment ranging from 1 :1 to 1:9, the spray-dried detergent particle has good powder properties, and the spray-dried detergent particle has improved biodegradability. It was also found that the slurry having the inventive copolymer of acrylic acid and the maleic acid did not form lumps which in-turn provides the spray-dried detergent particle with good powder properties.

The present inventors have surprisingly found that the spray-dried detergent particle includes a copolymer of acrylic acid and the maleic acid having a weight ratio between the acrylic acid segment and the maleic acid segment ranging from 1:1 to 1 :9, the spray-dried detergent particle has good powder properties, and the spray-dried detergent particle has improved biodegradability and provides a slurry with no lumps even when the alkali metal carbonate is from a natural source. The alkali metal carbonate from natural source have a propensity to lumping.

It was further preferably found that the desired powder properties is achievable by using low levels of the copolymer of acrylic acid and maleic acid having a weight ratio between the acrylic acid segment and the maleic acid segment ranging from 1 :1 to 1:9 in the spray-dried detergent particle. It is also surprisingly found that when the copolymer according to the present invention is present in the slurry, the slurry can include lower levels of the copolymer of acrylic acid and the maleic acid without impacting the performance. It was found that the copolymer of acrylic acid and the maleic acid polymer usage could be reduced drastically (up to 75% reduction) as compared to a copolymer of acrylic acid and maleic acid wherein the weight ratio between the acrylic acid segment and the maleic acid segment is 70:30 allowing for preparing a lump free slurry with an improved biodegradability due to lesser amount of polymer added to spray-dried detergent particle.

According to a first aspect of the present invention disclosed is a spray-dried detergent particle comprising:

(i) detersive surfactant;

(ii) 2 wt.% to 80 wt.% alkali metal carbonate;

(iii) copolymer of acrylic acid and maleic acid or salt thereof; wherein the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1 :1 to 1 :9 and wherein the alkali metal carbonate comprises an alkali metal carbonate from a natural source having a bulk density of at least 900 Kg/ m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers.

According to a second aspect of the present invention disclosed is a method of preparing a spray-dried detergent particle comprising the steps of: i) preparing an aqueous mixture comprising a copolymer of acrylic acid and maleic acid or salt thereof wherein the aqueous mixture has a water content ranging from 20 wt.% to 50 wt.% by weight of the aqueous mixture; ii) adding alkali metal carbonate to form an aqueous slurry, iii) spray-drying the aqueous slurry to form a spray-dried detergent particle, wherein the spray dried detergent particle comprises from 2 wt.% to 80 wt.% alkali metal carbonate and the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1 :1 to 1 :9; and wherein the alkali metal carbonate comprises an alkali metal carbonate from a natural source having a bulk density of at least 900 Kg/ m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers. According to a third aspect of the present invention disclosed is a use of a copolymer of acrylic acid and maleic acid or a salt thereof wherein the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1 :1 to 1:9 in a spray-dried detergent particle comprising 20 wt.% to 80 wt.% alkali metal carbonate from a natural source and having a bulk density of at least 900 Kg/ m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers and a detersive surfactant for providing a spray dried detergent particle with good powder properties.

According to a fourth aspect of the present invention disclosed is a use of a copolymer of acrylic acid and maleic acid or a salt thereof wherein the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1:1 to 1 :9 in a spray-dried detergent particle comprising 20 wt.% to 80 wt.% alkali metal carbonate from a natural source and having a bulk density of at least 900 Kg/ m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers and a detersive surfactant for providing good biodegradability.

Detailed Description of the Invention

According to a first aspect of the present invention disclosed is a spray-dried detergent particle, which includes a detersive surfactant, alkali metal carbonate, and a copolymer of acrylic acid and maleic acid or salt thereof.

Spray dried detergent particle

According to the first aspect of the present invention, the spray-dried detergent particle includes a detersive surfactant, alkali metal carbonate, and copolymer of acrylic acid and maleic acid or salt thereof.

Detersive surfactant:

Disclosed spray-dried detergent particle includes a detersive surfactant which may include those described in the literature, for example, in "Surface Active Agents and Detergents," Volumes 1 and 2 by Schwartz, Perry and Berch. Several detersive surfactant are also described in, for example, U.S. Pat. Nos. 3,957,695; 3,865,754; 3,932,316 and 4,009,114. In general, the spray-dried detergent particle may include a detersive surfactant selected from the group consisting of anionic surfactant, non-ionic surfactant, amphoteric surfactant, zwitterionic surfactant, cationic surfactant, or mixtures thereof. Preferably the spray-dried detergent particle includes an anionic surfactant, non-ionic surfactant, or mixtures thereof. More preferably the detersive surfactant is an anionic surfactant.

Anionic surfactant:

Preferably the detersive surfactant is an anionic surfactant. Suitable anionic detersive surfactant includes sulphonate anionic, sulphate anionic surfactant or mixtures thereof. The anionic surfactant is preferably an alkali metal (such as sodium and potassium) salts of the higher linear alkyl benzene sulfonates and the alkali metal salts of sulphated ethoxylated and sulphated unethoxylated fatty alcohols and sulphated ethoxylated alkyl phenols. The salt form will be suitably selected depending upon the spray-dried detergent particle and the proportions therein.

Suitable sulphonate surfactant include methyl ester sulphonate, alpha olefin sulphonate, alkyl benzene sulphonate, especially alkyl benzene sulphonate, preferably C10 to C13 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 C10 to C alkyl group, still preferably C10 to C14 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 surfactants include alkyl sulphate, preferably Cs to Cw alkyl sulphate, or predominantly C12 to Cw alkyl sulphate. One or more anionic surfactant may be present in the spray-dried detergent particle. Preferably the higher linear alkyl benzene sulfonate is a sodium alkylbenzene sulfonate surfactant (LAS), which preferably has a straight chain alkyl radical of average length of about 11 to 13 carbon atoms.

Specific sulphated anionic surfactants which can be used in the spray-dried detergent particle or the laundry composition of the present invention include sulphated ethoxylated and unethoxylated fatty alcohols, preferably linear primary or secondary monohydric alcohols with C10 to C , preferably C12 to Cw, alkyl groups and, if ethoxylated, on average from 1 to 15, preferably 3 to 12 moles of ethylene oxide (EO) per mole of alcohol, and sulphated ethoxylated alkylphenols with Cs to C alkyl groups, preferably Cs to Cg alkyl groups, and on average from 4 to 12 moles of EO per mole of alkyl phenol. A preferred sulphate detersive surfactant is alkyl alkoxylated sulphate, preferably alkyl ethoxylated sulphate, preferably a Cs to Cw alkyl alkoxylated sulphate, preferably a Cs to Cw alkyl ethoxylated sulphate, preferably the alkyl alkoxylated sulphate has an average degree of alkoxylation of from 0.5 to 20, preferably from 0.5 to 10, preferably the alkyl alkoxylated sulphate is a Cs 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.

Another preferred sulphate detersive anionic surfactants include alkyl sulphate, preferably Cs- 18 alkyl sulphate, or predominantly C12 to C alkyl sulphate. The alkyl sulphate, alkyl alkoxylated sulphate and alkyl benzene sulphonates may be linear or branched, substituted or unsubstituted.

The alkyl sulphate, alkyl alkoxylated sulphate and alkyl benzene sulphonates may be derived from petrochemical material, biomaterial or a waste material. The anionic surfactant may include the surfactant derived from petrochemical material and biomaterial or a waste material. Other suitable anionic detersive surfactant include, soaps, alkyl ether carboxylates. Suitable anionic detersive surfactant may be in salt form, suitable counter-ions include sodium, calcium, magnesium, amino alcohols, and any combinations thereof. A preferred counterion is sodium.

Non-ionic surfactant:

Suitable non-ionic detersive surfactant are selected from the group consisting of: Cs to G alkyl ethoxylates, such as, NEODOL® non-ionic surfactants from Shell; Ce to C12 alkyl phenol alkoxylates wherein preferably the alkoxylate units are ethyleneoxy units, propyleneoxy units or a mixture thereof; C12 to G alcohol and Ce 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 C alkyl alkoxylated alcohol, preferably a Cs to C 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 Cs to C 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. More preferably the betaine is cocoamidopropyl betaine.

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 spray-drying processing conditions in a spray-drying tower. More preferably those which are thermally stable when the spray-drying tower includes air with inlet air temperature ranging from 250°C to 500°C and those which are chemically stable at the pH conditions of the spray-drying slurry. Non-limiting examples of the anionic surfactant includes the ones mentioned above.

Preferably the spray-dried detergent particle includes from 1 wt.% to 50 wt.% detersive surfactant. More preferably the detersive surfactant is an anionic surfactant. Preferably the amount of detersive surfactant ranges from 1 wt.% to 50 wt.%, still preferably from 5 wt.% to 50 wt.%, more preferably 8 wt.% to 50 wt.%, still more preferably from 10 wt.% to 50 wt.%. Still preferably the amount of detersive surfactant is preferably in an amount ranging from 1 wt.% to 40 wt.%, still preferably from 5 wt.% to 40 wt.%, more preferably 8 wt.% to 40 wt.%, still more preferably from 10 wt.% to 40 wt.%. Preferably the amount of detersive surfactant in the spray dried detergent particle is not less than 1 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 45 wt.%, preferably not more than 40 wt.% or still preferably not more than 30 wt.%.

Alkali metal carbonate:

The spray-dried detergent particle according to the first aspect of the present invention includes from 2 wt.% to 80 wt.% alkali metal carbonate. The alkali metal carbonate includes an alkali metal carbonate from a natural source. The alkali metal carbonate from a natural source has a bulk density of at least 900 Kg/ m ³ . The alkali metal carbonate has at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers.

The alkali metal carbonate is preferably selected from the group consisting of sodium carbonate, potassium carbonate or mixtures thereof, preferably sodium carbonate. More preferably the alkali metal carbonate is sodium carbonate, and the spray-dried particle preferably includes potassium carbonate as a further alkali metal carbonate. In addition to the alkali metal carbonate the spray-dried detergent particle may include other alkaline carbonate ingredients which includes alkali metal bicarbonate, alkali metal sesquicarbonate, or mixtures thereof. Alkali metal carbonate from natural source

Preferably the natural source is from a mining process. Preferably the natural source from which alkali metal carbonate is prepared is trona. Trona is a mineral having sodium sesquicarbonate (Na2CO3.NaHCO3.2H2O). Trona is generally used for the manufacture of soda ash by well-established techniques which generally include milling the trona, which has either been mined or dredged depending on the location of the trona deposit and calcining the milled trona to produce soda ash. Still preferably the alkali metal carbonate natural source is made from trona source via the monohydrate process. The alkali metal carbonate formed from natural source such as trona has lowered porosity and lower wettability.

Preferably the alkali metal carbonate is sodium carbonate. Still preferably the alkali metal carbonate is a dense alkali metal carbonate, preferably dense sodium carbonate. The dense alkali metal carbonate is preferably those from a natural source. The dense alkali metal carbonate has a bulk density of at least 900 Kg/m ³ , more preferably the alkali metal carbonate has a bulk density ranging from 900 Kg/m ³ to 1250 Kg/m ³ , preferably 900 Kg/m ³ to 1200 Kg/m ³ , still preferably 950 Kg/m ³ to 1200 Kg/m ³ , more preferably from 1000 Kg/m ³ to 1200 Kg/m ³ , still more preferably from 1000 Kg/m ³ to 1100 Kg/m ³ .

Preferably the sodium carbonate is soluble in water. The sodium carbonate has a solubility of 45.5 g/100 mL at 100°C.

Preferably the weight average particle size of alkali metal carbonate ranges from 200 micrometers to 500 micrometers.

Preferably the alkali metal carbonate has not more than 50 parts by weight of the alkali metal carbonate of particles with weight average particle size less than 75 micrometers, still preferably not more than 45 parts by weight of the alkali metal carbonate of particle with weight average particle size less than 75 micrometers, still more preferably not more than 35 parts, further preferably not more than 25 parts by weight of the alkali metal carbonate of particle with weight average particle size less than 75 micrometers, still preferably not more than 10 parts by weight of the alkali metal carbonate of particle with weight average particle size less than 75 micrometers. Preferably the alkali metal carbonate has from 10 parts to 50 parts by weight of the alkali metal carbonate of particles with weight average particle size less than 75 micrometers. However, the present inventors have surprisingly found that even when the number of fines increases in the alkali metal carbonate, the present invention provides for good slurry processing and the spray dried detergent particle has good powder properties. The slurry properties were observed to be not affected even when 50 parts by weight of the particles of alkali metal carbonate had an average particle size less than 75 micrometers.

According to the present invention the alkali metal carbonate has at least 20 parts by weight of the alkali metal carbonate of particle with weight average particle size less than 75 micrometers, still preferably at least 25 parts, still preferably at least 30 parts, further preferably at least 35 parts, still more preferably at least 40 parts, still furthermore preferably at least 45 parts, but typically not more than 50 by weight of the alkali metal carbonate of particle with weight average particle size less than 75 micrometers. Preferably from 20 parts to 50 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers, still preferably from 20 parts to 35 parts, also preferably from 25 parts to 35 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers.

Alkali metal carbonate from synthetic source

The alkali metal carbonate preferably further includes a synthetically prepared alkali metal carbonate. This means that, in addition to the alkali metal carbonate from the natural source the spray-dried particle also comprises a synthetically prepared alkali metal carbonate. The synthetically prepared alkali metal carbonate has lower bulk density which provides lesser lumps. However synthetically prepared alkali metal carbonate is not available widely. The lower bulk density alkali metal carbonate may preferably be synthetically prepared from known process which includes the Solvay process or Hou process. The bulk density of the alkali metal carbonate from synthetic source is preferably from 400 Kg/m ³ to 800 Kg/m ³ , still preferably 400 Kg/m ³ to 800 Kg/m ³ , more preferably 600 Kg/m ³ to 800 Kg/m ³ , still more preferably from 600 Kg/m ³ to 700 Kg/m ³ .

Alkali metal carbonate according to the first aspect of the invention has a bulk density of at least 900 Kg/m ³ , still preferably a bulk density of 900 Kg/m ³ to 1250 Kg/m ³ , also preferably a bulk density of 901 Kg/m ³ to 1250 Kg/m ³ . The alkali metal carbonate with bulk density of 900 Kg/m ³ to 1250 Kg/m ³ has a higher tendency to form lumps. However, the present inventors have surprisingly found that even when the bulk density of the alkali metal carbonate is 900 Kg/m ³ or higher still preferably 1000 Kg/m ³ or higher, still preferably ranging from 1000 Kg/m ³ to 1100 Kg/m ³ , in presence of the copolymer according to the present invention the slurry forms lower amount of lumps and is easily processable. The spray dried detergent particle provides for good powder properties.

The amount of the alkali metal carbonate with weight average particle size of less than 75 micrometers may be as high as 50 parts by weight of the alkali metal carbonate due to multiple handling and attrition.

The spray-dried detergent particle according to the present invention includes from 2 wt.% to 80 wt.% alkali metal carbonate, more preferably the spray-dried detergent particle includes from 10 wt.% to 60 wt.% alkali metal carbonate. More preferably the amount of alkali metal carbonate in the spray dried detergent particle is not less than 5 wt.%, still preferably not less than 8 wt.%, more preferably not less than 10 wt.%, still more preferably not less than 15 wt.%, but typically not more than 70 wt.%, preferably not more than 65 wt.% or still preferably not more than 50 wt.%.

Copolymer acrylic acid and maleic acid or salt thereof:

According to the first aspect of the present invention the spray-dried detergent particle includes a copolymer of acrylic acid and maleic acid or salt thereof wherein the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1 :1 to 1 :9. More preferably the weight ratio of acrylic acid segment to the maleic acid segment ranges from 1 :1.5 to 1 :9, more preferably from 1 :1.2 to 1 :9, still more preferably from 1 :2 to 1 :9, furthermore preferably from 1 :2.5 to 1 :9, still further preferably from 1 :3 to 1 :9, still furthermore preferably from 1 :3.5 to 1 :9 and also preferred are ranges from 1 :4 to 1 :8, more preferably from 1 :5 to 1 :8, also preferably from 1 :6 to 1 :8.

The copolymer of acrylic acid and maleic acid has a weight average molecular weight ranging from 1000 to 100,000, more preferably from 1000 to 75000, more preferably 1000 to 65000, still more preferably from 1000 to 60000, still more preferably from 1500 to 60000, still more preferably from 2000 to 60000, still more preferably from 2000 to 30000, more preferably from 2000 to 25000.

It is highly preferred that the copolymer according to the first aspect of the present invention has a weight average molecular weight in the range from 1000 to 25000 and a weight ratio of acrylic acid segment to the maleic acid segment from 1 :1 to 1 :9, still preferably from a weight average molecular weight in the range from 2000 to 25000 and a weight ratio of acrylic acid segment to the maleic acid segment from 1 :1 to 1 :9 and still further preferably where the weight average molecular weight in the range from 1000 to 5000 and a weight ratio of acrylic acid segment to the maleic acid segment from 1 :1 to 1 :9.

Water-soluble salts of the copolymer of acrylic acid and maleic acid are also suitable for the present invention. The salts include those selected from non-limiting examples selected from alkali metal, ammonium and substituted ammonium salts.

Preferably the amount of copolymer of acrylic acid and maleic acid in the spray dried detergent particle ranges from 0.05 wt.% to 2 wt.%, more preferably from 0.05 wt.% to 0.5 wt.% still preferably from 0.05 wt.% to 0.3 wt.%, further preferably from 0.05 wt.% to 0.2 wt.%, also preferably from 0.1 wt.% to 0.3 wt.%. Preferably the amount of copolymer of acrylic acid and maleic acid in the spray dried detergent particle is not less than 0.06 wt.%, still preferably not less than 0.07 wt.%, more preferably not less than 0.08 wt.%, still more preferably not less than 0.09 wt.%, but typically not more than 1.5 wt.%, still preferably not more than 1 wt.%, further preferably not more than 0.8 wt.%, still preferably not more than 0.5 wt.%, still further preferably not more than 0.45 wt.%, more preferably not more than 0.3 wt.% or still more preferably not more than 0.25 wt.%.

Preferred ingredients:

The spray dried detergent particle according to the present invention may preferably include an alkaline silicate. Non-limiting examples of the silicate includes alkali metal silicates, alkaline earth metal silicates or mixtures thereof. Preferably alkali metal silicate. Preferably the silicate may be selected from sodium silicate, potassium silicate, sodium-potassium double silicate, lithium silicate or mixtures thereof are particularly preferred. More preferably the alkaline silicate is sodium silicate. The alkaline silicate may be liquid or solid form, preferably they may be crystalline silicates or soluble amorphous silicates.

The alkaline silicate is preferably having an approximate ratio of alkali oxide to silicon dioxide (M2O to SiC>2) of 1 : 1 .6 to 1 :3.3, preferably 1 : 1.6 to 1 :2.85, still preferably from 1 :2 to 1 :2.85 and most preferably 1 :2 to 1 :2.7. Orthosilicate, having the formula M4SiO4, is the most alkaline having a M2O to SiO2 ratio of 2:1. Metasilicate, M2SiOs, has a M2O to SiO2 ratio of 1 :1. The so called “water glass” silicates, which are soluble in water, have a M2O to SiO2 ratio of 1 :1.6 to 1 :3.3, preferably silicate with a M2O to SiC>2 ratio of from 1 :2.0 to 1 :2.7 where M is an alkaline earth metal, alkali metal, preferably alkali metal. Most preferably the M is sodium (Na).

Preferably the composition of the spray-dried detergent particle includes from 3 wt.% to 20 wt.% alkali metal silicate builder, more preferably from 4 wt.% to 17 wt.%, still more preferably from 8 wt.% to 20 wt.%.

Other builders:

Inorganic phosphate builders are preferably present at relatively low levels, for example less than 5 wt.%, still preferably less than 3 wt.%, further preferably less than 1 wt.% in the spray- dried detergent particle. Most preferably the spray-dried detergent particle is substantially free of inorganic phosphate builders. By substantially free it is meant that the spray dried detergent particle does not include any deliberately added inorganic phosphate builder. Most preferably the spray-dried detergent particle includes 0 wt.% inorganic phosphate builder. Preferably the spray-dried detergent particle includes 0 wt.% inorganic phosphate builder.

Similarly, the zeolite builders are preferably present at relatively low levels, for example less than 5 wt.%, still preferably less than 3 wt.%, further preferably less than 1 wt.% in the spray- dried detergent particle. Most preferably the spray-dried detergent particle is substantially free of zeolite builders. By substantially free it is meant that the spray dried particle does not include any deliberately added inorganic zeolite builder.

Filler:

Advantageously the spray-dried detergent particle may include a filler. The filler acts as a balancing ingredient and can be a neutral inorganic salt, mineral or mixtures thereof. Preferably the filler is selected from the group consisting of alkali metal sulphate, alkali metal chloride, alkaline earth metal carbonate or mixtures thereof. Still preferably the fillers are selected from the group consisting of sodium sulphate, magnesium sulphate, calcium magnesium carbonate (dolomite), calcite, sodium chloride or calcium carbonate, magnesium carbonate or mixtures thereof. Preferably the filler is sodium sulphate, sodium chloride, calcium carbonate (calcite) or mixtures thereof. More preferably the filler may be preferably sulphate, alkaline earth metal salt of carbonate, sodium chloride or a mixture thereof. Still more preferably the filler includes a combination of alkali metal sulphate and alkali metal chloride. Preferably the composition of the spray-dried detergent particle includes from 0 wt.% to 88 wt.% still preferably from 1 wt.% to 88 wt.% filler, further preferably from 1 to 60 wt.% filler, still more preferably from 25 to 60 wt.% filler.

Further optional ingredients may also be advantageously added to the spray-dried detergent particle which includes but are not limited to, any one or more of the following: soap, sequestrants, calcium chloride, sodium bicarbonate, other inorganic salts, fluorescers, dyes, anti-redeposition agents such as sodium carboxy methyl cellulose, slurry stabilizers such as homopolymers of acrylic acid; ethylene and maleic anhydride, and of vinyl methyl ether and maleic anhydride, usually in salt form; viscosity modifiers, hydrotrope, defoaming agents, antioxidants, colourants, shading dyes and combinations thereof.

Preferably the amount of water present in the spray dried detergent particle is from 0 wt.% to 4.5 wt.%, preferably 0 wt.% to 4 wt.%, still more preferably from 0.5 wt.5 to 3.5 wt.%

Preferably the spray-dried detergent particle has a pH ranging from 10.5 to 11.5 when measured using a 1 wt.% solution with distilled water at room temperature.

Preferably the spray-dried detergent particle has a bulk density of less than 650g/L. Preferably the spray-dried detergent particle has a weight average particle size of from 250 micrometers to 600 micrometers.

Process for preparing the spray dried detergent particle:

According to a second aspect, the present invention provides a method of preparing a spray- dried detergent particle comprising a step of preparing an aqueous mixture. The aqueous mixture includes a copolymer of acrylic acid and maleic acid or salt thereof according to the first aspect. The aqueous mixture has a water content ranging from 20 wt.% to 50 wt.% by weight of the aqueous mixture.

The next step involves adding an alkali metal carbonate to the aqueous mixture having a water content ranging from 20 wt.% to 50 wt.% to form an aqueous slurry. The aqueous slurry preferably includes a detersive surfactant. Preferably the detersive surfactant may be preformed and added to the aqueous slurry or the detersive surfactant may be prepared in-situ.

Preferably the aqueous slurry includes from 1 wt.% 50 wt.% detersive surfactant. Preferably the aqueous slurry may preferably include other thermally stable ingredients selected from a nonlimiting list including fillers, silicate, antifoam and mixtures thereof.

Preferably the alkali metal carbonate comprises up to 50 wt.% by weight of the alkali metal carbonate of particles with an average particle size less than 75 micrometers (fines).

Preferably the amount of the acrylic acid maleic acid copolymer present in the aqueous slurry ranges from 0.03 wt.% to 3.25 wt.%.

Next step involves spray-drying the aqueous slurry to form a spray-dried detergent particle, wherein the spray dried detergent particle comprises from 2 wt.% to 80 wt.% alkali metal carbonate and the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1 :1 to 1 :9; and wherein the alkali metal carbonate comprises an alkali metal carbonate from a natural source having a bulk density of at least 900 Kg/m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers.

Preferably the spray-dried detergent particle according to the present invention is prepared from a spray-drying process from an aqueous slurry where 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.

The pump system includes one or more pump, the pump is preferably a high-pressure pump. In a preferred embodiment, the pump system includes a first pump which is typically a low- pressure pump, such as a pump that is capable of generating a pressure of from 1 to 10 bar (1 x10 ⁵ to 1x10 ⁶ Pa), this pressure ensures proper flooding of the second pump. Typically, the second pump is a high-pressure pump, such as a pump that is capable of generating a pressure ranging from 20 bar to 200 bar (2x10 ⁶ Pa to 2x10 ⁷ Pa). Optionally, the aqueous detergent slurry is 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/mixer in which the aqueous slurry is formed. Preferably disintegrator is positioned between the pumps. The flow rate of the aqueous detergent 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.

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 particle. Preferably the spray drying process involves the step wherein the slurry is injected with a gas before spray drying. Still preferably wherein the gas is selected from air, nitrogen gas, carbon dioxide or combinations thereof.

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/hot steam temperature introduced into the spray drying tower is the range from 150°C to 500°C depending on the evaporation capacity and sizing of the tower. Preferably the tower exhaust air temperature can range from, 50°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 detergent slurry introduced into the spray nozzle of the spray drying tower is preferably at a temperature ranging from 45°C to 95°C. The spray drying tower may be a co-current spray drying tower but are less common. Preferably the spray-dried powder exiting the spray-drying tower has a temperature of less than 150°C, and still preferably less than to 100°C.

Preferably, the spray-drying zone is under a slight vacuum. Preferably the vacuum is controlled by the speed and/or damper setting of the inlet and outlet air fans. The negative pressure in the spray- drying tower can be measured by any available means. Typically pressure sensors are present in the spray-drying zone (inside the spray-drying tower). Preferably the vacuum pressure in the spray drying zone ranges from -10Nm ^-2 to -600Nm ^-2 , preferably -10Nm ^-2 to - 300Nm ^-2 to improve the cooling of the spray-dried detergent particle. Typically, the maximum pressure one can use is determined by the structural strength of the spray-drying tower and care must be taken not to exceed this maximum vacuum so that no undue stress is placed on the spray-drying tower.

Some ingredients may also be sprayed into the tower along with the slurry. These include thermally stable ingredients which are not compatible with the slurry. Non-limiting examples of these includes magnesium sulphate.

Optionally, laundry ingredients in liquid form which cannot be added via slurry or tower may be sprayed onto the spray-dried detergent particle. The laundry ingredients in liquid form includes but is not limited to non-ionic surfactant, melted fatty acid or mixtures thereof. The spraying of the laundry ingredients in liquid form 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.

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 any similar process. Preferably a flow aid such as zeolite, calcite, silica or dolomite is added to the spray-dried detergent particle before air-lifting. Preferably, the spray-dried detergent particle is subjected 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.

The spray-dried detergent particle may itself be used as fully formulated laundry composition. Typically, further laundry ingredients are dry-added to the spray-dried detergent particle to form a fully formulated laundry detergent composition, this dry addition of further laundry ingredient to the spray-dried particle (generally referred as base powder) is generally termed as postdosing. The post dosed ingredients include but is not limited to alkali metal gluconate, MGDA, isethionates preferably sodium coco isethionate, hydrotropes preferably selected from the group consisting of SCS, STS, SXS and combinations thereof.

The spray-dried detergent particle is typically post dosed or sprayed 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. The spray-dried detergent particle may itself be used as fully formulated laundry composition. The laundry detergent composition may be compressed to form tablets. Preferably the laundry detergent composition comprises from 2 wt.% to 100 wt.% of the spray-dried laundry detergent particle according to the first aspect or obtainable from the process of the second aspect provided herein above.

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.

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).

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, mannanases, G-glucanases, arabinosidases, hyaluronidase, chondroitinase, laccase, and amylases, or mixtures thereof. A typical combination is an enzyme combination that includes 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.

Polymers

Another suitable polymer is cellulosic polymer, preferably selected from alkyl cellulose, alkyl alkoxyalkyl cellulose, carboxylalkyl cellulose, alkyl carboxyalkyl, more preferably selected from carboxymethyl cellulose (CMC) including blocky CMC, methyl cellulose, methyl hydroxyethyl cellulose, methyl carboxymethyl cellulose, and mixtures thereof.

Other suitable polymers include polysaccharide polymers such as celluloses, starches, lignins, hemicellulose, and mixtures thereof.

Other suitable polymers are soil release polymers. Suitable polymers include polyester soil release polymers. Other suitable polymers include terephthalate polymers, polyurethanes, and mixtures thereof. The soil release polymers, such as terephthalate and polyurethane polymers can be hydrophobically modified, for example to give additional benefits such as sudsing.

Packaging and dosing

The spray dried detergent particle or a laundry composition having the spray dried detergent particle prepared according to the invention may be packaged as unit doses in polymeric film soluble in the wash water. Alternatively, the spray-dried detergent particle or a composition including the particle of the invention may be supplied in multidose plastic packs with a top or bottom closure. Preferably the laundry detergent composition compressed to form tablet may be packaged in a single use pouch. A dosing measure may be supplied with the pack either as a part of the cap or as an integrated system. The packaging material suitable for packaging may include but not limited to multilayer polyethylene film, laminate, paper based, and other materials known to a person skilled in the art. Preferably the packaging material is selected from material which are biodegradable or recyclable.

Method of use

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 involves the step of diluting the dose of detergent composition with water to obtain a wash liquor and washing fabrics with the wash liquor so formed. In automatic washing machines the dose of detergent composition 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 concentrations. The dilution step preferably provides a wash liquor which comprises inter alia from about 3 to about 20 g/wash of detersive surfactants (as are further defined above).

The spray-dried detergent particle or the laundry composition comprising the spray-dried detergent particle in diluted wash liquor is contacted with at least a portion of the soiled material and then optionally rinsing the soiled material. The soiled material may be subjected to a washing step prior to the optional rinsing step. In the washing stage, the water temperature may range from 5°C to 60°C. The water to soiled material ratio may be from 1 :1 to 30:1. The composition may be employed at concentrations of from 500 ppm to 15000 ppm in solution.

Handwashing/soak methods and combined handwashing with semi-automatic washing machines may also be used.

According to a third aspect of the present invention disclosed is a use of a copolymer of acrylic acid and maleic acid or a salt thereof wherein the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1:1 to 1:9 in a spray-dried detergent particle comprising 20 wt.% to 80 wt.% alkali metal carbonate from a natural source having a bulk density of at least 900 Kg/ m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers and a detersive surfactant for providing a spray dried detergent particle with good powder properties. According to a fourth aspect of the present invention disclosed is a use of a copolymer of acrylic acid and maleic acid or a salt thereof wherein the copolymer comprises a weight ratio of acrylic acid segment to the maleic acid segment ranging from 1 :1 to 1:9 in a spray-dried detergent particle comprising 20 wt.% to 80 wt.% alkali metal carbonate from a natural source having a bulk density of at least 900 Kg/ m ³ and wherein at least 20 parts by weight of the alkali metal carbonate has a weight average particle size less than 75 micrometers and a detersive surfactant for providing good biodegradability.

These and other aspects of the invention will be illustrated with reference to the following nonlimiting examples.

Examples

Example 1 : Preparing a 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. In this experiment sodium silicate and sodium sulphate was added. Copolymer of acrylic acid and maleic acid was then added to the aqueous mixture and the water content of the aqueous mixture was at 35 wt.%. The copolymer in the spray-dried detergent particle according to the present invention had a weight ratio between the acrylic acid segment and the maleic acid segment of 50:50 (1 :1), while the copolymer used in the spray-dried detergent particle in the conventional formulation (Ex-A) had a weight ratio of 70:30. Next 19.11 wt.% sodium carbonate was added to the aqueous mixture to form the aqueous slurry. The sodium carbonate from natural source (Trona) had from 20 parts to 25 parts (by weight of the alkali metal carbonate) had a weight average particle size of 75 micrometers. The bulk density of the alkali metal carbonate was around 1100 Kg/m ³ .

The composition of the spray-dried detergent particle and the corresponding aqueous slurry according to the present invention (Ex-1) and a conventional spray-dried detergent particle (Ex- A) are provided in the table 1 below.

Table 1

Example 2: Evaluation of the effect of the copolymer of acrylic acid and maleic acid according to the present invention on lump formation in the aqueous slurry.

An aqueous slurry having the composition as shown in table 1 below was prepared. The aqueous slurry was then passed through a 2mm sieve, and a gentle tapping was given. Visible lumps formed on the sieve was visually evaluated by a trained panel using a Lump assessment scale. The rating of the lumping was done using a lump assessment scale which is a scale from 0 to 5, where a rating of 0 was provided for a lump free slurry, 1 for few lumps, 2 to 3 for high lump and a rating of 4 to 5 indicates excess lumps. A score of 0 or 1 is acceptable for carrying out smooth operation in an industrial scale.

Table 2

The data in table 2 shows that the aqueous slurry according to the present invention (Ex 1) having co-polymer with acrylic acid to maleic acid with a weight ratio of acrylic acid segment to maleic acid segment of 50:50 (1 :1) has similar lump assessment score as that shown by conventional aqueous slurry (Ex A) having a co-polymer with acrylic acid segment to maleic acid segment with a weight ratio as 70:30. The aqueous slurry according to the present invention (Ex 1) has similar scores to the conventional slurry (Ex A) despite a reduction in the amount of the inventive copolymer by 75%, which suggests that the co-polymer with acrylic acid to maleic acid having an acrylic acid segment to maleic acid segment of 1 : 1 has a higher efficacy for providing an aqueous slurry with no lumps.

Example 3: Evaluation of the effect of the copolymer of acrylic acid and maleic acid according to the present invention on the powder properties of the spray-dried detergent particle

The aqueous detergent slurries (Ex 1, Ex A) was spray dried in a counter-current spray drying tower. The aqueous detergent slurry was maintained at a temperature of 82°C and pumped under a pressure of 4.7 X 10 ⁶ NOT ² , into a counter current spray-drying tower with an air inlet temperature of around 350-400°C and a mild negative pressure of 150 Nm’ ² The spray-dried particle had a moisture content of 2 wt.% to 3 wt.%. The spray-dried particle was sprayed with 0.5 wt.% non-ionic surfactant in a rotary drum mixer (low shear) followed by layering with flow aid which was microfine dolomite and cooled in an airlift.

The spray-dried detergent particle collected post airlift were evaluated for powder properties and the evaluation results are provided in Table 3.

Table 3

Spray-dried detergent particle

The data on table 3 shows that the spray-dried detergent particle according to the present invention having a co-polymer with weight ratio between acrylic acid segment to maleic acid segment of 50:50 has powder properties identical to conventional spray-dried detergent particle having a co-polymer with weight ratio between acrylic acid segment to maleic acid segment of 70:30 even when lower levels of the copolymer are used in the spray-dried detergent particle of the present invention (Ex 1).