CA2069937A1 - Concentrated aqueous liquid bleach compositions - Google Patents

Abstract

Concentrated aqueous liquid bleach compositions are disclosed, to be used preferably as bleach additives, containing from 30 % to 60 % by weight of a solid water-soluble peroxygen compound suspended in a liquid phase, and 0-4 % by weight of anionic surfactant.

Description

3 ~ J 7 w o 9 1 / o 9 1 o 3 P c r / u s g o / o o 1 2 CONCENTRATED AOUEOUS TTQUID
~ BTT~CH CO~SITIO~S
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- Technical Field The present invention relates to concentrated aqueous liquid bleach compositions, to be used preferably as bleach additives, containing from 30% to 60% of a solid water-soluble peroxygen compound suspended in a li~uid phase.

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Bac~around In European Patent Applications 293 040 and 294 904, have been described aqueous detergent compositions having a pH above 8 containing an anionic sur^actant at conventional - levels, i.e. above 5% by weight, ty~ically from 15% to 40%
by weight, and a solid, water-soluble peroxygen bleach .
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WO 91/09103 ~ J~I 3 7 PCT/US90/070i dispers_d i-l - "~-ci i- -~a~e~ cl~tent li~uid ~has2.

In European ~atent A~plication 294 304 were specifically descrlbed compositions containing at least 5%
anionic sur_~c_ant, at least 5~ builder, and perborate bleach oa ~isl-s ha;,'~ng o -fer~bly ~Qen formed ~y in situ QC-- S ~ 1 1 ~ -` ~

This tec..,.olcyy provided an answer to the'long-felt need for aqueous liquid detergent compositions containing a peroxygen bleach, which are stable and efflcient at the same time; indeed, attempts to formulate such compositions in the past featured non-aqueous-type executions, or hydrogen-peroxidé-containing compositions, formulated at a pH around 8, where stability was acceptable but performance from the bleach was not optimal: representative of this art are :

European Pa'ent 0 086 511, granted July 2, 1986 to The Procter & Gamble Company, disclosing aqueous liquid detergent compositi*ns having a pH below 9 and comprising organic surfactants, oxygen bleach, fatty acid and a water-soluble calcium salt.
DE-OS 35 11 5~5, published October 17, 1985, disclosing non-aqueous liquid detergent compositions comprising sodiumperborate monohydrate and an activator for the perborate. FR 2.579.615, published Octo~er 3, 1986, disclosing similar non-aqueous compositions which further comprise catalase inhibitors.

EP A-293 040 and 294 904 are, ho~ever, representative of "dilute" liouid detergent compositions, and do not encompass compositions with a very high concentration of :.
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WO 91/09103 ~ 3 ~ " 7 PCT/US90/07012 water-soluble peroxygen bleach. Ther2 is a nec~d for such "concentrat2s", in particular ^or us_ as ~Ibi~ac^ .
additives".

Indeed, while bleach-containing detsrgent compositions have proven quite useful, there is a raccgnized inrerest for tha consumer to ho able to use th.o bleach component in an optional manner, or to U52 aL a s?eci.ic ti~-.2 during ~hQ
. wash cycle of a washing machine, dependir.g on his speci-Lic needs or habits.
' Bleach additives have been developed for that purpose, and the commercially available ones are in solid form, consisting typically of sodium perborate and activator thereof, mixed as a powder.

Such bleach additives in solid form suffer the dis dvantage of slow dissolution, which impairs the efficiency; in addition, formation of spots on the fabrics may occur, due to very high localized concentration of the bleach.

Bleach compositions based on hydrogen peroxide are well-known too, and are disclosed in s.g. EP-A-9 839; such compositions are mainly used for hard-surface cleaning :~ applications, and are not desirable for use during the washing cycle of a washing machine. Drawbacks are low solution pH, and therefore poor efficiency, and high level ~:~ of free hydrogen peroxide in the product, not desirable for ~:: consumer safety reasons.

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WO 91/0~103 ~ J~'J `J 3 PCT/US90/070.

Iher~ di~t~s suitable for use in washing machine, which have no ; dissolution p obl~ms and whish, cnce added to ~he wash medium, can be immediately ef~^ective on -the _abrics;

; It has now bean suxpLisil~gly found ~ha a~leolls liauid bleach compcs~ticns w ~ high ~ol_nts Oc su-perded solid peroxygen som..pour.d c~n be fo~ul2ted, wi ~cu~ airing ~e chemical st~bili~-y O~ 2 ccmpositior.; i~ has Lurth2r been discovered ~hat unllX2 in the compositions OL E~A 293 040 and 294 904, the amount of anionic surfactant in the present concentrated compositions must be kept under 4~ by weight, since higher amounts alter the present ~viscosity/pourabiling characteristics of the present concentrated composition.
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The present invention therefore answers 'he above-mentioned needs, by providing concentrated aqueous liquid bleach compositions, containing high amounts of solid peroxygen compound, which are s,able upon storage, ~, show excellent viscosity/pourability characteristics, and dissolve quickly and efficiently in ~ha wash medium.
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e present compositions, which e~hibit an alXaline pH, allow to obtain an optimal performance from the bleach ; component.

SummarY

The present invention consis~s o~ aqueous liquid bleach ~,"
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~, , -; WV 9t/09~03 ~ J.S J :~; PCT/US90/07~12 compositions having a pH of a~ least 8, comp.isii, a aOiidt water-soluble peroxygen compound suspended in a liquid phase containing water and at least one water-mlscible organic solvent, preferably an aliphatic monoalconol such as ethanol, characterized in, that it contains ~rom 20~ to 40%, preferably 30% to 50~ by weight of th2 com~-s''_i-n, --the water-soluble pero~ygen compound, and ~hat ~_ conca ns 0 to 4% of anlonic surfactant.

etailed Description , m e water-soIuble solid peroxygen compound is present in the compositions herein at levels of from 30~ to 60% by weight of the total composition, preferably 30% to 50~ by weight.

Examples of suitable water-soluble solid peroxygen compounds include the perboraLes, persulfates, peroxydisulfates, perphosphates and the crystalline peroxyhydrates formed by reacting hydrogen peroxide with sodium carbonate (forming percarbonate) or urea. Preferred peroxygen bleach compounds are perborates and percarbonates.

Most preferred in the present context is a perborate bleach in the form of particles having a weight-average particle diameter of from 0.5 to 20 micrometers, preferably 3 to 15 micrometers.

The required small particle size can best be achieved - :

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WO 91/09103 PCT/US90/070.

by in-situ crystalli2ation, t~irpicall~ OL^ pe~~orat2 monohydrate.
In-situ crystallization encompass2s prccesses involving dissolution and recrysc211i7ation., as in tna dissolurion o~
perborate monohydrate and subsequent formation GL ~er~orat2 tetrahydrate. Recr~stalli.~2tion ;.nay also 'r.~.e place oy allowing pe~cra~a mCn5hYd__~e ~~ "2 ~-iS~ 1 ;a_~r, whereby tne monohydrat2 di.ca~,iy recr~!5~a 1 i zes inco che tetrahydrate, r/ithout dissolution step.
-In-situ crystallization also encompasses processes involving chemical reactions, as when sodium perborate is formed by reacting stoichiometric amounts of hydrogen peroxide and sodlum metaborate or borax.

; m e suspension system for the solid peroxygen component ;: herein.consists in a liquid phase that comprises water and a water-miscible organic solvent;
This makes it possible to incorporate in the liquid detergent compositions herein a high amount of solid wate~-soluble peroxygen compound, while~keeping the amount of available oxygen in solution below 0.5% by weight ~of the liquld phase, preferably below 0.1%. Less than one thenth of the total amount of peroxygen compound is dissolved in :: the liquid phase; the low level of available oxygen in solution is in fact critical for the stability of the ` system.
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The standard icdometric methcd (: s dosc ibed .or . instance in Methoden der Organischen Chemie, Houben Weyl, 1953, Vo. 2, page 562) is suita~le to determine the ~ available oxygen (AVO) content oî the composition.

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W O 91/09103 ' ~ ~J'`) " ~ '' PC~r/US90/07012 In order to ensure complete equilibration between liquid and solid phasesj the compositions are to be 'cept after mixing for three days at room temperature before the AV0 titration. Before measuring the products are thoroughly shaken in order to ensure correct sampling.

For th~ dstermination of the available o~.ygen (~to) n, the liquid phase, samples of the compositions are centrifuged for 10 minutes at 10.000 rpm. The liquid is then separated from the solid and titrated for availaole oxygen.
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It is not necessary that the organic solvent be fully miscible with water, provided that enough of the solvent mixes with the water of the composition to affect the solubility of the peroxygen compound in the described ; manner. Fully water-soluble solvents are preferred for use herein.

The water-miscible organic solvent must, o, cours , be compatible with the peroxygen bleach compound at the pH
that is used. Therefore, polyalcohols having vicinal " hydroxy groups (e.g. 1,2-propanediol and glycerol) are less desirable when the peroxygen bleach compound is perborate.
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Examples of suitable water-miscible orsanic solvents include the lower aliphatic monoalcohols; ethers of diethylene glycol and lower monoaliphatic monoalcohols;
specifically ethanol, n-propanol; iso-propanol; butanol;
polyethylene glycol (e.g., PEG 150, 200, 300, 400);
dipropylene glycol; hexylene glycol; methoxyethanol;
ethoxyethanol; butoxyethanol; ethyldiglycolether;
benzylalcohol; butoxypropanol; butoxypropoxypropanol; and .

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mixtures thereof. Prererred sol-ven.s includo ethanol;
iso-propanol, l-methoxy2-propano ~r.d _ucyl-i~iycsleuner.
A preferred solvent system is ethanol.

Although the presence or absence or other ing-redients plays a role, the amount or ~zila~l 3 '~i-J'^ i~ lut~on is largely de er~inc-d by ~he ratio T~'a~_r, Grgc:n-c soi;i_n~. ~t is not necessary however to use mor3 o~an:ic solv~ont than is needed to ~eep th2 amount o~ available oxysen in solution below 0.5%, preferably below O.l~.
In practical terms, the ratio ~ater orgznic solvent is, for most systems, in the range from O:l to 1:3, preferably from 5:1 to 1:2.

The present liquid bleach compositions exhibit a pH (1%
solution in distilled water) of at least 8, preferably of at least 9, more pre~erably at least 9.5. The alkaline pH
j~ allows to get a good bleaching action of the peroxygen compound, particularly when the peroxygen is a perboraLe.

; The compositions herein preferably contain a nonionic ~j or cationic surfactant, or a mixture thereof, at total ~ ~ levels of from l to 6%.
`, , The nonionic surfactants are conventionally produced by condensing ethylene oxide with a hydrocarbon having a reactive hydrogen atom, e.g., a hydroxyl, carboxyl, or amido group, in the presence of an acidic or basic catalyst, and include compounds havi~~ the general formula RA(CH2CH2O)nH wherein R represents the hydrophobic moiety, A represents the group ca_~ying ~he reactive hydrogen atom and n represents the average number of - ethylene oxide moieties. R typicall~ contalns from ~bout 8 ~`', .~, :

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;` WO 91/09103 ~ 3 I Pcr/us90/070l2 to 22 carbon atoms. They can also be formed by the condensation or propylene oxide with a lower molecular weight compound. n usually varies from about 2 to about 24.

The hydrophobic moiety ol the nonionic compound is preferably a primary or secondary, straight or branched, aliphatic alcoAol having from about 8 to about 2-~, preferably from about 12 to about 20 carbon atoms. A more complete dlsclosure of suitable nonionic surfactants can be found in U.S. Patent 4,111,855. Mixtures of nonionic surfactants can be desirable.
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A preferred class of nonionic ethoxylates is represented by the condensation product of a fatty alcohol having from 12 to 15 carbon atoms and from about 4 to 10 moles of ethylene oxide per mole of fatty alcohol.
Suitable species of this class of ethoxylates include :
the condensation product of C12-C15 oxo-alcohols and 7 moles of ethylene oxide per mole of alcohol: the condensation product of narrow cut C1~-C15 oxo-alcohols and 7 or 9 moles of ethylene oxide per mole of fatty(oxo)alcohol; the condensation product of a narrow cut C12-C13 fatty(oxo)alcohol and 6,5 moles of ethylene oxide per mole of fatty alcohol; and the condensation products of a C10-Cl~ coconut fatty alcohol with a degree of ethoxylation (moles EO/mole fatty alcohol) in the range from 5 to 8. The fatty oxo alcehols while mainly linear can have, depending upon the processing conditions and raw material olefins, a certain degree of branching, particularly short chain such as methvl branching.

A degree of branching in the range from 15% to 50%
(weight %) is frequently found in commercial oxo alcohols.
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2i,7 3$~ 7 WO 91/09103 PCT/US90/07~

-- 10 - , Preferred nonionic ethoxylated com~onen~s can aiso ~2 represented by a mixtur2 o. ~ se~a,-at21~i e~G;~i~ d nonionic surfactants having a different degr2e of ethoxylation. For example, the nonionic erno~IlQt~
surfactant containing from 3 to 7 moles or ~ lene oxide per mole of hydrophobic moiety ~nd a second ^~.hc~ a-c~d species having from 8 to lA. moles e- e~ r.Q o~ e~
mole of hydrop'nobic -moiety. A pr~ferr-d nonion~c ethoxylated mixute contains a l~wer ethoxylato wAich is tne condensation product of a Cl2-C15 oxo-alcohol, wi~h up to 50% (wt) branching, and from about 3 to 7 moles of ethylene oxide per mole of fatty oxo~alcohol, and a higher ethoxylate which is the condensation product of a ~ C16-Clg oxo-alcohol with more than 50% (wt) branching -~ and from about 8 to 14 moles of ethylene oxide per mole of i branched oxo-alcohol.
' y Examples of suitable cationic surfactants include quaternary ammonium compounds of the formula RlR2R3R4N+x , wherein R1 is C12-C2 b alkvl or hydroxyalkyl; R2 is Cl-C4 alkyl or C12-C20 alkyl or hydroxyalkyl or Cl-C4 hydroxyalkyl; R3 and R4 are each Cl-C4 alkyl or hydroxyalkyl, or C6-C8 ;-~ aryl or alkylaryl; and X is halogen. Preferred are mono-long chain quaternary ammonium compounds (i.e., compounds of the a~ove formula wheren R2 is Cî-C4 alkyl or hydroxyalkyl).
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The compositions herein may also contaln anlonic surfactants; however, it has been found that anionic surfactants, if used at levels a~ove ~.% by weight, could give problems with respect to the vlscosity/pourability characteristics of the pres~nt c~m~ositions.
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` WO ~l/0'~l03 ~ ~ 5~, v i PCT/USgO/07012 Accordingly, anionic surfactants, if used, are present at levels up to 4% by weight, preferably up to 1% by weight.
Synthetic anionic surfactants, can be represented by the general formula Rlso3M wherein R1 represents a hydrocarbon group selected from the group consisting of straight or branched alXyl radicals containir.g from a~out 8 to about 2~ caroon atoms and alkyl phenyl radicals containing from about 9 to about 15 carbon atoms in the ; alkyl ~roup. M is a salt forming cation which typically is selected from the group consisting of sodium, potassium, ammonium, and mixtures thereof.

A preferred synthetic anionic surfactant is a water-soluble salt of an alkylbenzene sulfonic acid containing from 9 to 15 carbon atoms in the alkyl group.
Another preferred synthetic anionic surfactant is a water-soluble salt of an alkyl sulfate or an alkyl polyethoxylate ether sulfate wherein the alkyl group contains~from about 8 to about 24, preferably from about 10 to about 20, preferably from about 1 to about 12 ethoxy groups. Other suitable anionic surfactants are disclosed in U.S. Patent 4,170,565, Flesher et al., issued October 9, 1979.

The present compositions may contain a builder, preferably no more than 4% of the total composition.
If present, such builder can consist of the inorganic or organic types already described in the art;
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Examples or inorganic `ouilders include the phosphourus-based builders, e.g., sodium tripolyphosphate, sodium pyrophosphate, and aluminosilicates (zeolites).
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'' ' , . ' ' WO 91/U9103 2 ~ , 3 . PCT/US90/0701 Examples of organic bullders are repres2ncod by polyacids such as CitLic acid, nicrllo~riace~ c aci~, ana mixtures of tartrate monosuccinate with tartrate disuccinate. Preferred build~rs for use here~ n 2 re ci'ri-acid and alk(en)yl-substituted succinic acid compounds, wherein alk(en)yl contains from l0 to l6 carbon a cms. ~r.
amples of ~his group of compo~-ds is d~decer.,1 s c_ ;. 5 acid. Polymeric carboxylate builders inclusi~e o,~
polyacrylates, polyhydroxy acrylates and polyacrylates/polymaleates copolymers can also be used.
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The compositions herein may also contain fur~her additives at levels of from 0.05% to 2%.
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These additives include polyaminocarboxylates such as ethylenediam motetracetic acid, diethylenetriamino-pentacetic acid, ethylenediamino disuccinic acid or the water-soluble alkali metals thereof. Other additives include organo-phosphonic acids;
particularly preferred are ethylenediamino tetramethylenephosphon1c acid, diethylenetriamino pentamethylenephosphonic acid and aminotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid.
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Bleach stabilizers such as ascorbic acid, dipicolinic acid, sodium stannates and 8-hydroxyquinoline can also be included in these compositions, at levels between 0.0l and 1% .
, The compositions herein can contain a series of further optional ingredients which are mostly used in addi~tive ~ levels, usually below about 5%. Examples of the like :~' .

WO 91/~9103 ~ J~ PCT/~S90/07012 additives include : enzymes and enzymatic stabilizing agents, opacir^iers, agents to improve the machine compatibility in relation to enamel-coated surfaces, bactericides, dyes, perfumes, brighteners and the like.

Suitable enzymes include the detergent proteases, amylas2s, lipases and cellulases. Prsferred enzymatic stabilizing agents ror use herein are salts of formic acid or acetic acid, e.g. sodium formate and sodium acetate.

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Use of the Com~ositions . , .
The present compositions are mainly intended to be used as bleach additives, in the washing cycle of washing machines, on top of conventional granular or liquid detergent compositions.
Typically, said bleach additives will be added to ~he wash medium, separately from the detergent composition, at a time chosen by the consumer or predetermined by washing-machine manufacturers, preferably at the beginning of the wash cycle.

m e use of the concentrated bleach compositions of the present invention as bleach-additives in the wash cycle of a washing machine, is the preferred one; however, other uses can be contemplated, such as pretreatment product for heavily-soiled fabrics, or soaking product; the use as bleach àdditive is not necessarily limited to the washine-machine context, and the compositions of the present invention can be used in combination with bleach-compatible handwash compositions.

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2~3~`7 The datergent composltions t3 be used in c~ '.-.a' cn with the present bleach additives should be bleach-compatible; preferably the present liouid aoueous bleach additives will be used in combination wi'~h bleach-compatible liquid detergent compositions.
., A typical bleach-compatibl2 liquid d2teLs2nt composition has the following for~ula :

Inqredients Compositlon ~t%
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Linear Alkyl 3enzene Sulfonate 12-14%.
C13_15 alcohol ethoxylated (EO7) 6- 8%
Coconut Alkyl Sulfate 2- 3%
Dodecenyl succinic acid 10-}2%
Oleic Acid 1,5-2.5%
Citric Acid 2.5-3.5%
DrPMPA* 0.7-0.~3%
Ethanol 3- 4%
PropanedioI 1.5-2.5%
minors and water up to 100 .
* Diethylene triamine pentamethylene phosphonic acid ' .~ .
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~xamples me rollcwing liquid aqueous concentrated bleach compositions are prepared :

, Ir.q.ed.2nts ComPosition wt%

A I II III IV
------_______________________________ ~ , Sodium Perborate tetrahydrate 48 48 48 37 31 Ethanol ~ 8.5 8.5 8.5 8.5 8.0 DrPMPA* 0.8 0.8 0.8 0.8 0.8 C13_15 alcohol ethoxylated (EOs) 0.3 5.3 0.3 5.35.0 AlkyI benzene sulfonic acid 5.3 0.5 0.5 Dodecenyl succinic acid 0.5 0.5 0.5 0.5 .-Cocoyl dimethyl-2-hydroxyethyl) ammonium chloride ) - - 1.6 ;Sodium hyaroxide ------- to pH 10 --------------water & minors . ------- to 100 ----------------~' .
____________________________________________________________________ : viscosity (cps) NOT 4000 1500 2600 2700 ; at 60 rpm POURABLE

: *~Diethylene triamine pentamethylene phosphonic acid e ~bo~e co~positions were prepared according to the following method : ~ -. .
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WO 91/09103 ~ ~ 3,~ 3 ~ PCT/USgo/0701 ~`

The solvent(s) and the phosphonic acid are dissolv2d n water and the pH is adjusted to about 8 with sodium hydroxide. The surfactant(s), if present, are then added and, if needed, the pH is adjusted bac~c to 8 T~ith sodium hydroxide.

, m e sodium perborate monohydrate is then added under stirring, at room temperature; it recrystallizes to perborate tetrahydrate within ~ few hours of stlrring. T~2 recrystallization process can be speeded up by adding, prior to the perborate, some seed crystals of sodium perborate tetrahydrate of small particle size (5-lO
microns). In practice this is best done by adding a small percentage (less than 10%, typically around 5%) of the finished composition of this patent. Bleach-containing dilute aqueous detergent compositions (such as described in EP~A-293 040 and EP-A-294 904) can also be used as seeding compositions.
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After the recrystallization is completed, minor ingredients such as dyes, perfumes etc. are added.
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The composition can also be prepared by~reacting in situ hydrogen peroxide and sodium metaborate (or borax).
In this case sodium metaborate powder is added to the ; solvent(s)/surfactant(s) solution; then an aqueous solution of hydrogen peroxide is added. Sodium perborate tetrahydrate crystallizes from the solution, and then the pr~duct is completed as described above.
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Composition A is prepared for comDarative purposes, to show the criticality of the anionic surfactant level.
Composition A appears to be non pourable.

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T~e comnositions of Exa~ples I to IV show perfectly acceptable viscosity characteristics, and have excellent stabil1ty ~ehaviour upon storage : , '::
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Claims (13)

Claims:

1. An aqueous liquid bleach composition having a pH of at least 8, comprising a solid, water-soluble peroxygen compound suspended in a liquid phase containing water and at last one water-miscible organic solvent, characterized in, that it contains from 30% to 60%, by weight of the composition, of the water-soluble peroxygen compound, and that it contains from 0 to 4% by weight of anionic surfactant.

2. A composition according to claim 1, wherein the water-miscible organic solvent is an aliphatic monoalcohol.

3. A composition according to claim 2, wherein the water-miscible solvent is ethanol, and is present in a water:ethanol ratio of from 8:1 to 1:3.

4. A composition according to claim 1, wherein the water-soluble peroxygen compound is present at levels of from 30-50% by weight.

5. A composition according to claim 1, wherein the solid, water-soluble peroxygen compound is a perborate tetrahydrate.

6. A composition according to claim 5 wherein the perborate tetrahydrate is in the form of particles having a weight-average particle diameter of from 0.5 micrometer to 20 micrometer.

7. A composition according to claim 6, wherein the perborate tetrahydrate particles have been formed by recrystallization of a perborate monohydrate.

8. A composition according to claim 1, wherein the solid, water-soluble peroxygen compound is a percarbonate.

9. A composition according to claim 1 having a pH of at least 9.

10. A composition according to claim 1 which contains from 1 to 6% by weight of a nonionic or cationic surfactant, or mixture thereof.

11. A composition according to claim 1 which contains from 0 to 1% by weight of anionic surfactant.

12. The use of the composition of claim 1 as a bleach additive for a detergent composition.

13. The use according to claim 12 wherein said detergent composition is a bleach-compatible liquid detergent composition.