Process for preparing low bulk density carbonate salt

Abstract

The present invention relates to a process of preparing alkali metal carbonate, more particularly to alkali metal carbonate having lowered bulk density. It is desired to provide a low-density sodium carbonate which is also environmentally friendly and involves lower green-house gas emissions while maintaining desirable properties. It is desired to provide an alkali metal carbonate which has low bulk density and is obtained from natural source. The present inventors have found that when an aqueous solution of dense sodium carbonate is mixed with a copolymer of acrylic acid and maleic acid, with specific mole ratio of maleic acid to acrylic acid, the treated sodium carbonate surprisingly has a lowered bulk density and preferably has improved dispersibility, liquid carrying capacity and enhanced porosity.

Description

[0001] P0001181 CPL

[0002] 1

[0003] PROCESS FOR PREPARING LOW BULK DENSITY CARBONATE SALT

[0004] Field of the Invention

[0005] 5 The present invention relates to a process of preparing alkali metal carbonate, more particularly to alkali metal carbonate having lowered bulk density.

[0006] Background of the Invention

[0007] Sodium carbonate also known as soda ash is widely used as builder in homecare compositions. Sodium carbonate is commercially available as light soda ash and dense soda ash based on their average bulk density. Commercially available dense soda ash generally has an average bulk density of 900 Kg / m3to 1200 Kg / m3whereas the light soda ash generally has an average bulk density ranging from 400 Kg / m3to 800 Kg / m3.

[0008] 15 Sodium carbonate can also be produced by mining trona ore followed by surface treatment to produce soda ash. This is often called natural soda ash. Sodium carbonate is recovered from its ore by two processes namely the sesquicarbonate process and the monohydrate process, named after their respective crystallization products. Generally, the natural soda ash and is obtained by drying crystalline sodium carbonate monohydrate to remove its water of hydration.

[0009] 20

[0010] Light density sodium carbonate is desirable as it does not form lumps or aggregates with surfactants in slurries. Light density sodium carbonate is typically produced by a synthetic route such as the Hou process and Solvay process. This route generates higher greenhouse gas emissions than natural soda ash, so from an environmental aspect, natural dense soda ash is preferred.

[0011] It is desired to provide a low-density sodium carbonate which is also environmentally friendly and involves lower green-house gas emissions while maintaining desirable properties.

[0012] 30 US4151266 (Robey et al., 1979) discloses a one stage method for producing free-flowing absorptive particles of Wegscheider’s salt (Na2CC>3.3 NaHCCh) having a low bulk density, low alkalinity and low friability. The process involves reacting high bulk density, anhydrous sodium carbonate particles with carbon dioxide and steam at super atmospheric pressure. P0001181 CPL

[0013] 2

[0014] More recently W02006 / 081930 A1 (Unilever) discloses a process for preparing modified sodium carbonate carrier material which involves mixing sodium carbonate with polyaspartate to form crystal growth-modified sodium carbonate.

[0015] 5 It is desired to provide an alkali metal carbonate which has low bulk density and is obtained from natural source.

[0016] It is further desired to provide a low bulk density alkali metal carbonate which has improved dispersibility.

[0017] Summary of the Invention

[0018] The present inventors have found that when an aqueous solution of dense sodium carbonate is mixed with a copolymer of acrylic acid and maleic acid wherein the copolymer comprises a mole ratio of maleic acid segment to the acrylic acid segment is greater than 1 :1 , the treated

[0019] 15 sodium carbonate surprisingly has a lowered bulk density and preferably has improved dispersibility, liquid carrying capacity and enhanced porosity.

[0020] It was further found that the low bulk density sodium carbonate formed in accordance with the first aspect of the present invention has improved porosity and a lowered bulk density while

[0021] 20 maintaining desired particle size.

[0022] According to the first aspect of the present invention provided is a process for preparing a low bulk density sodium carbonate, the process comprising the steps of:

[0023] (i) dissolving dense sodium carbonate preferably having an average bulk density ranging

[0024] 25 from 900 Kg / m3to 1250 Kg / m3in water to form an aqueous solution;

[0025] (ii) adding a copolymer of acrylic acid and maleic acid or a salt thereof to an aqueous solution, wherein the copolymer comprises a mole ratio of maleic acid segment to the acrylic acid segment greater than 1 :1 ;

[0026] (iii) removing the water content from aqueous solution to form low bulk density sodium carbonate;

[0027] According to a second aspect of the present invention provided is a low-density sodium carbonate having a bulk density less than 1000 Kg / m3, more preferably having a bulk density ranging from 400 to 900 Kg / m3, more 400 Kg / m3to 800 Kg / m3, also preferably 500 to 900 Kg / m3

[0028] 35 obtainable according to the process of the first aspect. P0001181 CPL

[0029] 3

[0030] According to a third aspect of the present invention provided is a carrier adjunct comprising the low bulk density sodium carbonate according to the second aspect or prepared according to the first aspect.

[0031] 5 According to a fourth aspect of the present invention provided is a detergent composition comprising the low bulk density sodium carbonate according to the second aspect or prepared according to the first aspect.

[0032] Detailed Description of the Invention

[0033] According to the first aspect of the present invention provided is a process for preparing low bulk density sodium carbonate.

[0034] Preferably the process according to the invention can be operated either in a batch / discontinuous mode or in a continuous mode.

[0035] 15

[0036] Step (i): Forming an aqueous solution comprising dense sodium carbonate:

[0037] According to the first aspect of the present invention provided is a process for preparing a low- density sodium carbonate involving a first step of dissolving dense sodium carbonate having an average bulk density higher than 900 Kg / m3to form an aqueous solution.

[0038] 20

[0039] Preferably the dense sodium carbonate has an average bulk density ranging from 900 Kg / m3to 1250 Kg / m3.

[0040] The dense sodium carbonate acts as a feed component for preparing the low-density sodium

[0041] 25 carbonate in accordance with the first aspect of the present invention. Preferably the dense sodium carbonate comprises sodium sesquicarbonate.

[0042] Preferably the dense sodium carbonate suitable for the process according to the present invention is sourced from trona ore. Trona-ores, deposits of which exist particularly in the state of Wyoming in the United States, are used for the production of sodium carbonate. The usable matter in these ore is sodium sesquicarbonate (Na2 CO3.NaHCO3.2H2O), which is generally present in a quantity on the order of 80% to 95% by weight. Preferably the trona includes a mixture of bicarbonate-carbonate salt.

[0043] 35 Preferably the ore is pre-treated with one or more physical operations which includes but is not limited to grinding, particle size fractionation, classification by densimetric, electrostatic or P0001181 CPL

[0044] 4 magnetic means for removing any impurities. Preferably the ore is pre-treated by calcination in order to convert the sodium sesquicarbonate into anhydrous sodium carbonate.

[0045] In the first step according to the present invention, dense sodium carbonate is dissolved in

[0046] 5 water to form an aqueous solution. Preferably the dense sodium carbonate is an ore comprising sodium sesquicarbonate. Preferably the dense sodium carbonate which acts as a feed is pretreated with a step of calcination and comprises anhydrous sodium carbonate.

[0047] Advantageously, the process of the present invention may also be suitable for commercially available dense sodium carbonate. Non-limiting examples of commercially available dense sodium carbonate includes those available under the trade name Soda Solvay® Dense from Solvay. The process of the present invention provides the benefit of preparing a low-density sodium carbonate either directly from the sodium carbonate or at various stages of converting the ore into dense sodium carbonate and can also be used to treat the commercially available

[0048] 15 dense sodium carbonate.

[0049] Preferably upon dissolution in water, dense sodium carbonate forms a saturated solution of sodium carbonate monohydrate. Preferably the amount of water added to the sodium carbonate is an amount which is sufficient to dissolve the dense sodium carbonate. Preferably at least

[0050] 20 100 grams of dense sodium carbonate per Kg of aqueous solution is added, more preferably at least 150 grams of sodium carbonate per Kg of the aqueous solution, still more preferably at least 200 grams of sodium carbonate per Kg of aqueous solution.

[0051] According to a preferred step the resulting aqueous solution is subjected to an aging step at a

[0052] 25 temperature of 65°C to 108°C, more preferably 92°C to 97°C and at the end of the aging the sodium carbonate monohydrate crystals are extracted from the solution by means of a particle size fractionation.

[0053] Preferably the aqueous solution has a pH of at least 8.

[0054] Preferably the aqueous solution comprises a surfactant. Preferably the surfactant is selected from the group consisting of anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant and mixtures thereof. P0001181 CPL

[0055] 5

[0056] Step (ii): Adding a copolymer of acrylic and maleic acid or a salt thereof to the aqueous solution According to the first aspect of the present invention, the next step in the process involves adding a copolymer of acrylic acid and maleic acid to the aqueous solution. The copolymer of acrylic acid and maleic acid or a salt thereof according to the first aspect of the present

[0057] 5 invention comprises a mole ratio of maleic acid segment to the acrylic acid segment of greater than 1 :1.

[0058] The step of adding a copolymer of acrylic acid and maleic acid in the process according to the present invention is preferably immediately before or after adding dense sodium carbonate to the water to form an aqueous solution. More preferably the copolymer of acrylic acid and maleic acid is added to the aqueous solution immediately after the addition of dense sodium carbonate.

[0059] Copolymer of acrylic acid and maleic acid or a salt thereof:

[0060] 15 The copolymer of acrylic acid and maleic acid or a salt thereof according to the first aspect of the present invention comprises a mole ratio of maleic acid segment to the acrylic acid segment of greater than 1:1. More preferably the mole ratio of maleic acid segment to the acrylic acid segment ranges from 1.2:1 to 9:1 , still preferably 1.2:1 to 2.33:1, more preferably from 1.25:1 to 2.33:1 , still more preferably from 1.3:1 to 2.33:1, furthermore preferably from to 1.5:1 to 2.33:1,

[0061] 20 still further preferably from 1.75:1 to 2.33:1 , still furthermore preferably from 1.8:1 to 2.33:1.

[0062] The copolymer of acrylic acid and maleic acid has a weight average molecular weight ranging from 10000 to 100000, more preferably from 10000 to 75000, more preferably 10000 to 65000, still more preferably from 10000 to 60000, still more preferably from 10000 to 50000, still more

[0063] 25 preferably from 15000 to 50000, still more preferably from 20000 to 50000, more preferably from 25000 to 50000.

[0064] 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 10000 to 100000 and a mole ratio of maleic acid segment to the acrylic acid segment greater than 1 :1, still preferably from a weight average molecular weight in the range from 10000 to 100000 and a mole ratio of maleic acid segment to the acrylic acid segment ranging from 1.5:1 to 2.33:1 and still further preferably where the weight average molecular weight in the range from 10000 to 50000 and a mole ratio of maleic acid segment to the acrylic acid segment ranging from 1.5:1 to 2.33:1. P0001181 CPL

[0065] 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 polymer is a sodium salt.

[0066] 5

[0067] Preferably the copolymer of acrylic acid and maleic acid is added in an amount ranging from 0.1 wt.% to 5 wt.%, still preferably from 0.1 wt.% to 3 wt.% based on the dry weight of the sodium carbonate added to the aqueous solution. For example, if 1000 Kg of sodium carbonate by dry weight is added to the aqueous solution then a 3 wt.% of copolymer of acrylic acid and maleic acid as provided herein will amount to 3% of 1000 which is 30 Kg of the copolymer of acrylic acid and maleic acid.

[0068] Additional polymers

[0069] Preferably in addition to the copolymer of acrylic and maleic acid, additional polymer may be

[0070] 15 added to the aqueous solution to aid the process of forming the low-density sodium carbonate.

[0071] Preferably the additional polymers include but are not limited to polyepoxysuccinic acid polymer, modified polyaspartate, polyaspartate, polyacrylates, and combinations thereof.

[0072] 20 Polyepoxysuccinic acid polymer (PESA):

[0073] Preferably the additional polymer is a polyepoxysuccinic acid polymer. The polyepoxysuccinic acid polymer has a general formula: wherein:

[0074] R1and R2are independently selected from H, Ci-Ce alkyl, -OH, -COOM;

[0075] M is selected from H, Na, K, NH4, or substituted ammonium;

[0076] Y is selected from -OH, -OR’, -NH2, -NHR’, -NR’2, in which R’ is selected from Ci-Ce alkyl; and n

[0077] 30 is from 2 to 20. P0001181 CPL

[0078] 7

[0079] Preferably R1and R2are independently selected from H, CH3; M is selected from H, alkali metal; Y is selected from OH, -OR3, -NH2 in which R3selected from Ci to Ce alkyl; and n is from 2 to 15. Still more preferably R1and R2are both H; M is selected from H, alkali metal; Y is selected from OH, - and n is from 2 to 10. Preferably R1and R2are H. Preferably M is an alkali

[0080] 5 metal, still preferably M is sodium.

[0081] More preferably the polyepoxysuccinic acid can be represented by the structure wherein M is H or Na, and n is from 2 to 10.

[0082] The polyepoxysuccinic acid polymer maybe used as singularly or in mixture. The "n" 20 represents an average number. In one embodiment, when polyepoxysuccinic acid polymer is a

[0083] 15 mixture, the polymer sample may be dominated by samples with n from 2 to 7, more preferably from 3 to 6.

[0084] A most preferred polyepoxysuccinic acid polymer can be identified using CAS number: 5 51274-37-4 (M=H), or 109578-44-1 (M = sodium).

[0085] 20

[0086] Commercially available polyepoxysuccinic acid polymer based chemical modifier is available as the sodium salt from Sirius International under the tradename Briteframe PESA.

[0087] Preferably the polyepoxysuccinic acid polymer is added in an amount ranging from 0.1 wt.% to

[0088] 25 5 wt.%, still preferably from 0.1 wt.% to 3 wt.% based on the dry weight of the sodium carbonate added to the aqueous solution. For example, if 1000 Kg of sodium carbonate by dry weight is added to the aqueous solution then a 3 wt.% of polyepoxysuccinic acid polymer as provided herein will amount to 3% of 1000 which is 3 Kg of the polyepoxysuccinic acid polymer.

[0089] 30 Modified polyaspartate:

[0090] Preferably the additional polymer is a modified polyaspartate. The modified polyaspartic acid polymer is selected from polyaspartic acid modified with an anionic pendant unit selected from P0001181 CPL

[0091] 8 the group consisting of aspartic acid, iminodiacetic acid, glutamic acid, citric acid and / or sodium citrate.

[0092] Preferably the modified polyaspartic acid is prepared from polysuccinimide (PSI) precursor.

[0093] 5 Preferably the polysuccinimide (PSI) precursor is reacted with a nucleophile. Preferably, the nucleophile involved in the ring opening reaction of the polysuccinimide (PSI) precursor includes but is not limited to those selected from alkali metal hydroxide, amines and alcohols. Preferably the alkali metal hydroxide is sodium hydroxide. Preferably the nucleophile is a combination of alkali metal hydroxide and amines or alcohols.

[0094] Preferably the amine or alcohol nucleophile also contains covalently bonded anionic groups. Preferably these anionic groups are carboxylates, sulfonates or sulfates. More preferably the nucleophile is selected from the group consisting of aspartic acid, iminodiacetic acid, glutamic acid, citric acid and / or sodium citrate. The ring opening of the polysuccinimide (PSI) precursor

[0095] 15 by the amine or alcohol nucleophile forms a modified polyaspartic acid, wherein some or all the constitutional repeat units in the modified polyaspartic acid comprises an anionic pendant unit.

[0096] Preferably the additional polymer includes a combination of polyaspartic acid and modified polyaspartic acid.

[0097] 20

[0098] Preferably the additional polymer is a modified polyaspartate modified with aspartic acid or a salt thereof wherein the modified polyaspartate is represented by the general formula (I): . Formula (I)

[0099] 25 wherein n + m has a value ranging from 5 to 100, more preferably between 10 and 40; and wherein o + p has a value ranging from 0 to 100, more preferably between 5 and 40. wherein -M is independently selected from a H atom or an alkali metal. Preferably M is an alkali metal, more preferably M is sodium.

[0100] 30 P0001181 CPL

[0101] 9

[0102] Preferably the additional polymer is a modified polyaspartate modified with glutamic acid or a salt thereof wherein the modified polyaspartate is represented by the general formula (II): Formula (II)

[0103] 5 wherein n + m has a value ranging from 5 to 100, more preferably between 10 and 40; and wherein o + p has a value ranging from 0 to 100, more preferably between 5 and 40. wherein -M is independently selected from a H atom or an alkali metal. Preferably M is an alkali metal, more preferably M is sodium.

[0104] 10

[0105] Preferably the additional polymer is a modified polyaspartate modified with iminodiacetic acid or a salt thereof wherein the modified polyaspartate is represented by the general formula (III): Formula (III) wherein n + m has a value ranging from 5 to 100, more preferably between 10 and 40; and wherein o + p has a value ranging from 0 to 100, more preferably between 5 and 40. wherein -M is independently selected from a H atom or an alkali metal. Preferably M is an alkali metal, more preferably M is sodium.

[0106] 20

[0107] Preferably the additional polymer is a modified polyaspartate modified with citric acid or a salt thereof wherein the modified polyaspartate is represented by the general formula (IV): P0001181 CPL

[0108] 10 Formula (IV) wherein n + m has a value ranging from 5 to 100, more preferably between 10 and 40; and wherein o + p has a value ranging from 0 to 100, more preferably between 5 and 40.

[0109] 5 wherein -M is independently selected from a H atom or an alkali metal. Preferably M is an alkali metal, more preferably M is sodium.

[0110] Preferably the modified polyaspartate is added in an amount ranging from 0.1 wt.% to 5 wt.%, still preferably from 0.1 wt.% to 3 wt.% based on the dry weight of the sodium carbonate added to the aqueous solution. For example, if 1000 Kg of sodium carbonate by dry weight is added to the aqueous solution then a 3 wt.% of modified polyaspartate polymer as provided herein will amount to 3% of 1000 Kg which is 30 Kg of the polyepoxysuccinic acid polymer.

[0111] Step (iii): Removing water to form the low-bulk density alkali metal carbonate

[0112] 15 According to the first aspect of the present invention the next step in the process involves removing water from the aqueous solution to form low-bulk density sodium carbonate.

[0113] The low-bulk density sodium carbonate formed by the process of the present invention has a bulk density lower than the dense sodium carbonate which is used as the feed component. The

[0114] 20 low-bulk density sodium carbonate formed by the process preferably has a bulk density less than 1000 Kg / m3, more preferably the low-bulk density sodium carbonate has a bulk density ranging from 400 Kg / m3to 900 Kg / m3, more preferably ranging from 400 Kg / m3to 800 Kg / m3, still preferably from 400 to 600 Kg / m3.

[0115] Preferably the resulting low bulk density sodium carbonate has a BET absorption pore size greater than 10 nanometers as measured using BET nitrogen absorption method.

[0116] Preferably the process of removing water from the aqueous solution is carried out in any equipment known in the art for such purposes. Preferably the water content may be removed by

[0117] 30 processes such as but not limited to settling, by centrifugation, by filtration or a combination of P0001181 CPL

[0118] 11 these separating means may used. Preferably the process of removing water is carried out by a drying operation. Advantageously the drying is carried out by spray drying, air drying, oven drying, drum drying, ring drying, freeze drying, solvent drying, microwave drying and combinations thereof.

[0119] 5

[0120] Preferably the drying equipment may be selected from a spray-drier, fluid bed dryer, a rotary dryer, a flash pneumatic conveyor dryer, oven dryer, drum dryer, ring dryer, a gravity dryer or combinations thereof.

[0121] Preferably the step of removing the water content from the aqueous solution is carried out to the extent that the formed sodium carbonate is free flowing. Preferably the formed sodium carbonate comprises from 2 wt.% to 9 wt.% free water content.

[0122] The process according to the invention allows to directly produce sodium carbonate crystals out

[0123] 15 of the aqueous solution having low bulk density.

[0124] Preferably the low bulk density sodium carbonate prepared according to the process has a BET absorption pore size greater than 10 nanometers as measured using BET nitrogen absorption method.

[0125] 20

[0126] After obtaining the low bulk density sodium carbonate, the low bulk sodium carbonate particles may preferably be washed with fresh water.

[0127] Low-bulk density sodium carbonate

[0128] 25 According to the second aspect of the present invention provided is a low-bulk density sodium carbonate obtainable according to the first aspect.

[0129] Preferably the low-bulk density sodium carbonate obtainable in accordance to the present invention has a bulk density ranging from 400 Kg / m3to 900 Kg / m3, still preferably from 400 Kg / m3to 900 Kg / m3.

[0130] Preferably the low-bulk density sodium carbonate obtainable in accordance to the present invention has a BET absorption pore size greater than 10 nanometers as measured using BET nitrogen absorption method.

[0131] 35 P0001181 CPL

[0132] 12

[0133] Laundry Adjunct

[0134] According to a third aspect of the present invention provided is a laundry adjunct comprising the light sodium carbonate and an active agent prepared in accordance with the first aspect of the invention.

[0135] 5

[0136] The low-density sodium carbonate prepared in accordance with the first aspect of the present invention was found to have the capacity to take up and hold large quantities of liquid components, which may be advantageously used in preparing an active adjunct for liquid active ingredient. By liquid active ingredient is meant those that are inherently liquid at processing temperature, or ingredient which may first be liquefied by melting or dissolving in a solvent. Non-limiting examples of liquid ingredient includes perfumes, oils, liquid surfactant preferably those which are selected from non-ionic surfactant, amphoteric surfactant, zwitterionic surfactant and mixtures thereof; aqueous paste or anionic surfactant, such as sodium lauryl ether sulphate.

[0137] 15

[0138] The low bulk density sodium carbonate may also be advantageously used as carrier material for hygroscopic ingredient which includes but is not limited to solid hygroscopic ingredient with a moisture content ranging from 0 to 20 wt.%. Preferably the hygroscopic active ingredient is selected from the group consisting of sequestrant, betaine amphoteric surfactant, alkyl

[0139] 20 polyglucoside anionic surfactant, nonionic surfactant, alkoxylated nonionic surfactant foam controlling agent, antiredeposition polymer and combinations thereof. Preferably the hygroscopic sequestering agent is an aminopolycarboxylate compound, more preferably the aminopolycarboxylate compound is selected from the group consisting of MGDA, GLDA, NTA, or mixtures thereof. Other preferred sequestering agent are sodium gluconate, and

[0140] 25 phosphonates and amino phosphonates including HEDP, EHDP, EDTMP and mixtures thereof. Mixtures of sequestering agents of the same or different classes are also preferred.

[0141] Preferably the betaine amphoteric surfactant is CAPB. Preferably the alkyl polyglucoside anionic surfactant have a hydrophobic fatty alcohol portion and a hydrophilic glucoside portion. Preferably, the alkyl part of the alkyl polyglucoside has carbon atoms in the range from 8 to 16, more preferably from 10 to 14, furthermore preferably from 12 to 14. The hydrophilic polyglucoside group containing from about 1.5 to 4, most preferably from 1.6 to 2.7 glucoside units. The alkyl polyglucoside surfactant has a formula RO(R10)tZxwherein Z is a moiety derived from glucose R is an alkyl group that contains from 8 to 16 carbon atoms; R1 is

[0142] 35 ethylene, propylene and / or glyceryl, t has a value which ranges from 0 to 10, most preferably 0 and where x is a number from 1.5 to 4 most preferably from 1.6 to 2.7. Suitable examples of P0001181 CPL

[0143] 13

[0144] APG include cocoglucoside (commercially available as PLANTACARE® 818 UP; BASF), caprylyl / capryl glucoside (commercially available as PLANTACARE® 810 UP; BASF) which both have carbon atoms from 8 to 16, lauryl glucoside (commercially available as PLANTACARE® 1200 UP) with carbon atoms from 8 to 16 and decyl glucoside (commercially

[0145] 5 available as PLANTACARE® 2000 UP) with carbon atoms in from 8 to 16.

[0146] Preferably the process for preparing the laundry adjunct includes the steps of:

[0147] (i) obtaining an active ingredient selected from liquid active ingredient or a solid hygroscopic ingredient with a moisture content ranging from 0 wt.% to 20 wt.%;

[0148] (ii) homogeneously mixing the active ingredient and the low bulk density sodium carbonate according to the first aspect of the present invention to form a laundry adjunct.

[0149] According to a second aspect of the present invention provided is a detergent composition comprising the light sodium carbonate prepared in accordance with the first aspect of the

[0150] 15 invention.

[0151] The low-density sodium carbonate prepared in accordance with the first aspect of the present invention was found to have good liquid carrying capacity, display good flow properties and was resistance to caking. These qualities of the low-density sodium carbonate can be

[0152] 20 advantageously used in detergent composition. According to any aspect of the present invention provided is a spray-dried base powder comprising the low-density sodium carbonate according to the present invention.

[0153] Preferably the detergent composition is a powder detergent composition. Preferably the free -

[0154] 25 flowing powder detergent composition comprises agglomerate particles comprising low density sodium carbonate. Preferably the agglomerate particles comprise surfactant.

[0155] Preferably the free-flowing detergent composition comprises spray dried particle particles comprising low density sodium carbonate. Preferably the spray dried particle particles comprise surfactant.

[0156] Preferably the free-flowing detergent composition comprises a combination of spray dried particle comprising low density sodium carbonate and agglomerate particle comprising low density sodium carbonate.

[0157] 35 P0001181 CPL

[0158] 14

[0159] Preferably the detergent composition is a unit-dose composition. Preferably the unit dose composition comprises a water soluble or dispersible pouch enclosing a free-flowing detergent composition as described herein above.

[0160] 5 Preferably the detergent composition is a bar composition comprising the low-density sodium carbonate according to the present invention.

[0161] Preferably the detergent composition is a tablet composition comprising the low-density sodium carbonate according to the present invention.

[0162] Preferably the detergent composition is a sheet composition comprising the low-density sodium carbonate according to the present invention, surfactant and a film forming polymer.

[0163] Examples

[0164] 15

[0165] Example 1: Preparation of the modified sodium carbonate according to the present invention

[0166] 15 grams of the natural dense sodium carbonate (having a bulk density of 0.95 g / cc to 1.15 g / cc) was dissolved in 60 mL of demineralized water at a temperature of 50°C to form an

[0167] 20 aqueous solution. 0.45 grams of a copolymer of acrylic acid and maleic acid wherein the copolymer comprises a mole ratio of maleic acid segment to the acrylic acid segment greater than 1 :1 was added to the aqueous solution and the solution was then placed in a 500 mL powder flask (pear shaped flask with four side indents). The flask was then placed on a rotary evaporator (water bath at 70°C, vacuum at 110 mbar) and the water removed. When the water

[0168] 25 was completely removed, the precipitate was removed and placed in an oven at 110°C for 120 minutes to form the modified sodium carbonate. The modified sodium carbonate was then removed, allowed to cool and then ground in a mortar and pestle to a visually consistent particle size.

[0169] Different modified sodium carbonates were prepared using different levels and different types of the additional polymer as provided in the process described above and as provided in table 1 below.

[0170] 35 P0001181 CPL

[0171] 15

[0172] Example 2: Evaluation of the sodium carbonate modified in presence of different copolymer of acrylic acid and maleic acid.

[0173] Measurement of the relative bulk density

[0174] 5 The relative bulk density of the modified sodium carbonate was determined relative to a light density soda ash taken as the standard.

[0175] A suitably sized receptacle (e.g. a 7mL glass vial) was taken and weighed (W1). It is then filled with light soda ash (with gentle tapping to ensure proper packing) until it begins to overflow. A flat blade is then drawn across the top to remove any excess powder and the vial weighed again (W2). From this, the weight of soda ash (W3) can be determined - W3 = W2 - W1.

[0176] To determine the relative bulk density of the modified sodium carbonate, the weight of the modified sodium carbonate (W4) was divided by W3 to give a relative bulk density of the

[0177] 15 modified sodium carbonate (RBD).

[0178] For example, if the weight of light soda ash was 10 grams and an equivalent volume of a modified sodium carbonate weighed 14.6 grams then the relative bulk density would be 14.6 / 10 = 1.46.

[0179] 20

[0180] Thus, sodium carbonate that are less porous that light soda ash (e.g. dense soda ash) will have a relative bulk density of greater than 1 whereas modified sodium carbonate that are more porous will have a relative bulk density of less than 1.

[0181] Table 1

[0182] The data in table 1 shows that the dense sodium carbonate when modified using copolymer of acrylic acid and maleic acid according to the present invention (Ex 1) provides lower bulk

[0183] 30 density as compared to the sodium carbonate modified with comparative copolymer (Ex A) at the same level of addition of the copolymer.

Claims

1. P0001181 CPL16CLAIMS1. A process for preparing a low-density sodium carbonate, the process comprising the steps of:(i) dispersing dense sodium carbonate preferably having an average bulk density ranging from 900 Kg / m3to 1250 Kg / m3in an aqueous solution;(ii) adding a copolymer of acrylic acid and maleic acid or a salt thereof to an aqueous solution, wherein the copolymer has a mole ratio of maleic acid segment to the acrylic acid segment greater than 1:1;(iii) removing the water content from the aqueous solution to form low-density sodium carbonate.

2. A process according to claim 1 wherein the low bulk density sodium carbonate has a bulk density less than 1000 Kg / m3and preferably a BET absorption pore size greater than 10 nanometers as measured using BET nitrogen adsorption method.

3. A process according to claim 1 or 2 wherein the step of adding copolymer of acrylic acid and maleic acid is immediately before or after adding dense sodium carbonate to the water to form an aqueous solution.

4. A process according to any one of the preceding claim 1 to 3 wherein the aqueous solution comprises a surfactant.

5. A process according to any one of the preceding claims wherein the mole ratio of maleic acid segment to the acrylic acid segment in the copolymer ranges from 1.2:1 to 9:1.

6. A process according to any one of the preceding claims wherein the process involves a step of adding an additional polymer to the aqueous solution wherein the additional polymer is selected from the group consisting of modified polyaspartate, polyepoxysuccinic acid, polyaspartate, copolymer of acrylic acid and maleic acid wherein the mole ratio of maleic acid to acrylic acid is less than 1:1 and / or more than 9:1.

7. A process according to claim any one of the preceding claims wherein the aqueous solution comprises at least 100 grams of the dense sodium carbonate per Kg of the aqueous solution.P0001181 CPL178. A process according to any one of the preceding claims wherein the copolymer is added in an amount ranging from 0.1 wt.% to 5 wt.% based on the dry weight of the dense sodium carbonate added to the aqueous solution.

9. A process according to any one of the preceding claims wherein the formed low bulk density sodium carbonate has a bulk density ranging from 400 Kg / m3to 900 Kg / m3, still preferably from 500 Kg / m3to 900 Kg / m3.

10. A process according to any one of the preceding claims wherein the aqueous solution has less than 35% solids by weight of the dissolved solids in the aqueous solution.

11. A process according to any one of the preceding claims wherein the low bulk density sodium carbonate prepared by the process comprises 90% by weight sodium carbonate.

12. A low bulk density sodium carbonate obtainable according to any one of the preceding claims having a bulk density less than 1000 Kg / m3and a BET absorption pore size greater than 10 nanometers as measured using BET nitrogen adsorption method.

13. A carrier adjunct comprising the low bulk density sodium carbonate according to claim 12 or prepared according to the process of any one of the preceding claims 1 to 11.

14. A detergent composition comprising the low bulk density sodium carbonate according to claim 12 or prepared according to the process of any one of the preceding claims 1 to 11 .

15. A detergent composition according to claim 14 wherein the detergent composition is a solid detergent composition, preferably a spray-dried laundry composition, agglomerated laundry composition, water-soluble or water-dispersible unit dose laundry article, tablet composition, bar composition, laundry sheet and combinations thereof.

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