CA1134237A - Detergent compositions - Google Patents

Abstract

C.1045 ABSTRACT OF THE DISCLOSURE:

The invention relates to a detergent composition in powder or bar form containing a surfactant, an alkali metal carbonate and a low level (1 to 5%) of orthophosphate, other phosphates being maintained at a level below 5%. A peroxygen bleach and other conventional additives are optionally present.
The compositions are suitable for washing fabrics in developing countries and are suitable as low cost products elsewhere.

Description

3~7 - 1 - C.1045 : ' DE~ERGE~ COMPOSIlI~NS

ECH~ICAL FIELD
Ihe present invention relates to detergent compositions in particulate or bar form which are adapted for fabric washing. ~he invention concer~s in partîcular such compositions w~ich are suitable for washing by hand in co`ol, - i.e. cold or lukewarm water, as occurs widely in so-called ~-~
developing countries and low cost formulations far use in developed countries.
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- ACKGROUND ARI ~
A major problem in formulating detergent products for fabric w-ashing by hand and in cool water~ is the difficult~ in reconciling the need for a highly effective detergency builder system which will adequately soften . ~

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- 2 - C.1045 water during use under adverse washing conditions, which often also include low product dosage, with the fact that the users of such composi-tions c~nnot in general afford the most effective systems which would otherwise be desired.
~or indeed do the economies of the developing countries always permit the importation of large tonnages of foreign detergency builder ma-terials such as sodium tripolyphosphate.
It has been proposed previously to use sodium carbonate as a detergency builder, and this material is widely available and relatively cheap. ~nfortuna-tely, however, sodium carbonate when used alone as the detergency builder does not function so effectively as would be desired, particularly at cool washing temperatures. Although the level of calcium ion concentration is lowered`to sufficient level by the presence of sodium carbonate, i.eO
` by precipitation of calcium carbonate, -the precipitatio~
process is a slow one and during the early part of the - wash cycle the calcium concen-tration i5 higher than is desired for effective washing. During the initial period before the sodium carbonate is fully effectivej there can be interac-tion between the calcium ions present and`
other ingredients in the detergent compositions. For example anionic detergent surfactants such as some sodium alkyl benzene sulphonates can be precipitated in the form of the calcium salts and this therefore contributes to a further reduction in detergency~` Other types of detergent surfactants are k~own which are not precipitated by calcium ion, for example nonionic detergen-t surfactants, but these more sophisticated detergent surfactants tend to be more expensiye, which mi-tigates against their use in relatively cheap formulations~
DISC~OS ~ O ~HE I~VENlIO~
~ he present invention seeks to provide a way of improving the effectiveness of sodium carbonate as a detergency builder, particularly under adverse washing .

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- ~ - C.1045 circumstances, but without imposing a heavy cost burden on ~heco~positions.` ~his has been achieved by including - a lo~ level of an orthophosphate salt in the composition.
~ccording to the present invention, there is provided an alkaline detergent composition for fabric washing comprising a detergent surfactant and an alkali metal carbonate, containing ( i) from about 10% to about 40% of a synthetic anionic, nonionic, amphoteric or zwitterionic detergent surfactant or mixture thereof;
( ii) from about 10% to about 40% of an alkali metal carbonate;
(iii) from about 1% to less than 5% of an orthophosphate material selected from orthophosphoric acid and the ammonium, sodium or potassium salts thereof; and ( iv) not more than 5% of other phosphate builder salts, all percentages being by weight o~ the composition.
~he composition may be in powder form or in the form of a laundry bar.
It ha~i been ~ound that the addition of the ortho-phosphate material together with the alkali metal' carbonate achieves a much more cost-e~fective building per~ormancè than either of the materials would do alone.
It appears that the presence o~ the lo~ level of orthophos-''~'"
phate makes the calcium ion concentration drop very ~uickly to a satisfactory low level~ after which the sodium carbonate maintains the calcium ion concentration at the low level. ~he resultant detergent compositions are cheaper because of the unsophisticated builder `
systems, and yet give satisfactory detergency under the adverse washing conditions.
BEST MODE_OF CARRYI~G OU~ INVE~IO~ ~
~ hè orthophosphate material used may be either potassium or preferably sodium orthophosphate, as the latter is cheaper and-more readily available~ ~ormally - ' ., ~ .
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_ 4 - C.1045 the trialkali metal salts are used, but orthophosphoric acid or the di- or mono-alkali metal salts~ e.g. disodium hydrogen orthophosphate or monosodium dihydro~en ortho-phospha-te could be used if desired -to form the CompoSitiQnS~
In the latter event o-ther more alkaline salts would also be present to maintain a high pH in the end product, with full neutralisation to the trialkali metal orthophosphate salts. ~he use of a mixture of the monosodium and disodium hydrogen orthophosphates in the ratio of abou-t 1:3 to 2:3, especially about 1:2, is particularly adva~tageous, as such a mixture is made as a feedstock for the production of sodium tripolyphosphate and is therefore readily available. lhe alkali metal ortho-phosphate can be used initially as the anhydrous or hydrated salt, for example as trisodium orthophosphate dodecahydrate. ~he amounts of the alkali metal ortho-phosphate are calculated in anh~drous form although it is preferred that the salts should be a-t least partially hydrated in the final detergent compositions, ~hether b~
initial use of the hydrated salts or by hydration during powder production. ~he amount of the alkali metal orthophosphate salt is preferabIy about 1% to about 4.5%
by wei~ht of the composition. ~dvantageousl~, the amount of phosphorus in the formulation, in the form of the orthophosphate, is from about 0.2% to about ~.5%.
` Some otherphosphate`builder salts may be present at low levels, e.g. not exceeding 5% by weight of the composition, although this is ~ot normally desired~ ~ow - levels of other phosphates are commonly present as impurities in the alkali metal orthophQsphates supplied, so the presence of the other phosphates-may in practice be unavoidable. Such other phosphate builder salts include in particular sodium tripol~phosphatè and sodium pyrophosphate and the corresponding potassium salts when 35 partassium orthophosphate is used. ~ `

~ 5 ~ Co1045 ~ he alkali me-tal carbonate salt used may be potassium or preferably sodium carbonate or a mixture thereof~ ~he - carbonate salt is generally fully neutralised, bu~ it may contain some potassium or sodium bicarbonate or sesqui-carbonate. Alkali metal percarbona-te may also be used.
~ he amount of the aIkali metal carbonate used can be varied between about 10% and about 40% by weight of -the compositions but it is preferred to use an ~moun-t of about 15% to about 30% by weight, and at least about 10% of the carbonate must be fully neutralised, based o~ the weight of the compositionO ~he amount of the alkali metal carbonate is determined on an anhydrous basis, although the carbonate salt may be hydrated before or during detergent production. The amount of bicarbonate can be up to about 20% by weight of the composition, which is e~uivalent to up to about 40% of sesquicarbonate, but it is pre~erred to ha~e a bicarbonate content of about 5 to 15% of the composition.
~he detergent compositions must include from about 10% to about 40% by weight of a synthetic detergent sur~actant. It is pre~erred to ha~e a relatively high level of detergent surfactant present in the compositions, that is at least about 20% by weight of the composi-tions as this facilitates the produc-tion of adequate 1ather~ levels under the conditions of usage in the developing countries, generally with a maximum level of about 30% for reasons o~ cost.
It is particularly preferred to use an anionic detergent surfactant as these tend to be cheaper and more readily availably in developing`countries. ~he alkali metal alkyl benzene sulphonates, especially sodium linear secondary alkyl (C10 C15) benzene sulphonate, are particularly preferred. However, other anionic detergent surfactants which æ e generally water-soluble alkali metal salts or organic`sulphates and sulphonates ha~ing ~, ' " . :

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- 6 - ~ C~1045 alkyl radicals containing from about 8 to 22 carbon atoms ~ may be employedO Examples of such o-ther anionic detergent surfactants are sodium and po-tassium alkyl sulphates~ especially those obtained by sulphating higher - 5 (C8-a18) alcohols produced ~or example from tallow or coconut oil; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from petroleum; sodium coconut oil fatty acid monoglyceride sulphates and sulphonates; sodium and potassium salts of sulphuric acid esters of higher (C8-C18) fatty alcohol-aIkylene oxide, p æticularly ethylene oxide, ~eaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralised with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine; alkane monosulphates such as those derived by reacting alpha-olefins (a8-C20) wi-th sodium bisulphite and those derived ` b~ reacting paraffins with ~2 and C12 and the hydrolysing with a base to produce a random sulphonate; and olefin sulphonates, which term is used to describe the material made by reacting olefins, particularly c8-a20 alpha-olefins, with S03 and then neutralising and hydrolysing `
the reaction product.
~onionic detergent sur~actants may`be used in the detergent compositions although this is not gener~
desired because of their relatively high costs and because they tend to result in decreased lather properties.~
However, they may be used to give a boost to detergency ~ -properties at relatively low levels of for example up ~~0 to about 5% of the composition. ~he nonionic detergent ` surfactants are the reaction products of compounds havin~
hydrophobic groups and a reactive hydrogen atom, for example aliphatic alcohols,~acids, amides or alkyl phenols ``- with alk~lene oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic .
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7 ~ ~ 3 ~ ~3 7 C 10~5 detergent surfactantS are alkyl (C6-~22) phenl-ethYlene oxide condensates, generally 5 to 25 E0, i.e. 5 -to 25 units of ethylene oxide per molecule; the condensation produc-ts of aliphatic (C6-~18) primary or secondar~
linear or branched alcohols with ethylene oxide, generally 6 to 30 ~0, and products made by condensation of ethylene oxide with the reaction products or propylene oxide and ethylenediamine. Other so-called nonionic detergent surfactants include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides~ Mixtures of amine oxides with ethoxylated nonionic compounds can also be used~ `
Amounts o~ amphoteric or zwitterionic detergent surfactan-ts may also be used in the compositions of the invention but this is not normall~ desired due to their relatively high cost. I~ any amphoteric or zwitterionic detergent surfactants are used it is-generally in small amounts in compositions based on the much more commonly used synthetic anionic and/or nonionic detergent surfacta~tsO
Ap æ t from the essential detergent surfac-tants and detergenc~ builders, the detergent compositions of the invention can contain an~ of the conventional additives in amounts of which such mate~ials are normall~ employed in ~5 fabric washing detergent compositions. However, the need to control the cost of products in practice precludes the `
- use of more expensive additives. Moreover, the washing conditions emplo~ed, particularl~ hand~washing i~ cool ~
water, make ;t less practical to use lather depressants, ` ~`
oxygen-based bleaching agents such as sodium per~orate and sodium percarbonate with or without peracid bleach precursors, or enz~mes such~as proteases and amylases.
However, where different washing conditions are used, such as machine washing at moderate or high temperatures, such additlves will generally be included in the compositions~

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~ 8 ~ Co1045 in particular from about 10% to about 50% of a peroxygen bleach. ~he additives which are more commonly used in detergent compositions suitable for -the developing countries include lather boosters such as alkanolamides, particularly the monoethanoamides derived ~rom palm kernel fatty acids and coconut ~atty acids, antiredeposition agents such as sodium carboxymethylcellulose, alkaline buffers such as sodium silicate, fluorescent agents, perfumes and colourants and the like.
It is particularly preferred to have present an inorganic filler salt to pro~ide the compositions with sufficient bulk at an acceptable cost. ~he amount of the filler salt is from about 5% to about 50%, preferably about 15% to about 40%, by weight of the composition.
~hese filler salts are generall~ considered to be inert materials, although in the case o~ the soluble salts there can be some smal] effect on detergency due to their affecting the ionic concentration. When any insoluble filler materials are used such as calcium carbonate, it is important to have them as fine~ divided as possible so as not to cause undue deposition on the fabric being washed.
~æamples of other suitable inorganic fillers are borax, ma~nesium silicate, talc, calcium sulphate, sodium aluminosilicate and bentonite or other clays.
As both alkali metal orthophosphate and alkali metal carbonate salts function as detergency builders by precipitàtio~ of their insoluble calcium salts, it can be advantageous to include an amount of an antideposition aid to ;n~ibit deposition of such insoluble salts on the fabrics. ~he most effective antideposition aids are `
anionic pol~electrolytes, especially pol~meric alipahtic carbox~lates, for example alkali metal or ammonium, e.g.
sodium, salts of homo- and co-polymers of acrylic acid or substituted acr~lic acids. ~he~amounts of an~ such anti-deposition aids is normally from about 0.05~0 to about 5%

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_ 9 _ ~ 3~ C.1045 by weight, preferably from about 0 1% to abou-t 2% by - weight, of the compositionsO ~Iowever, as such polymeric additives tend to be relatively expensive they æe preferably used, if at all, at low levels within this range in the compositions of the invention.
Some soap may also be included in the compositions of the invention but not as the sole detergent surfactant.
In general the soaps are relatively expensive and if used at only low levels they can have an undesirable suds depressing action. However, in some countries soap may be more widely available than imported sy~thetic detergent - surfactants in which case a proportion of soap may be used, preferably not exceeding about half of the total surfactant prese~t.
~he compositions of the invention are re~uired to be alkaline, but no-t too strongly alkaline as -this could result in fabric damage and also be hazardous for use, especially~in ma~ual washing. It is desired in practice that the composition should give a pE of from about 9 to 11 in use in aqueous wash solution, preferably from about 9.5 to 1005, as measured at a product concentration of about 0.1% w`/~ in water of 12~ (Ca) at 25C~ ~he pX of the detergent compositions in use is controlled by the amount and type of alkali metal orthophospha~e and alkali metal carbonate salts present and on any other alkàline salts `" which may be used, especially alkali metal silicate.
- Ap æt from its effect on pH control~ the presence in the detergent compositions of a a ount of an alkal~ metal silicate is generally advantageous in facilitating ~0 processing of the detergent compositions and giving generally improved powder properties. ~he type of alkali `` metal silicate used is preferably sodium silicate, for ;~
example sodium ortho-, meta- or pre~erably neutral or alkali~e silicate. ~he more highly`alkaline ortho- and ~5 meta silicates are normally only~use`d~at lower levelsa in admixture with neutral or alkaline sllicates.
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3~7 - 10 - C~1045 ~ he detergent compositions of the invention may be in particulate form, which includes powders and granules and they may be made by conventional -techniques, for example by granulation or by slurry making and spray drying processes, preferably so as to give substantially homogenous products. Ihe orthophosphate may be post-dosed to the composition. Alternatively, they may be in the form of laundry b æs which may be formed by conventional methods such as mixing and extruding.
~he invention is illustrated by the following ~xamples in ~rrhich parts and percentages are by weight and in which the amounts of the ingredients are expressed on an anh~drous basis, except where otherwise indicated.

In order to demonstrate the beneficial effect on calcium ion lowering by using mixed sodium orthophosphate and sodium carbonate detergency builders, some compositions were prepared as follows~: %
ngredient A ~ C D
Sodium alkyl benzene sulphonate 28 28 28 28 Sodiwm orthophosphate 4.5 - 4.5 Sodiw~ carbonate 20 24.5 - 20 Sodium silicate 10 10 10 10 Sodium sulphate ` 27~5 27~5 47.5 32.0 l~ater ~ 1Q 10 10 - 10 ~ach of these compositions was then added to water o~
initially 30~ ~ (Gaj at 25C, the product dosage being -3.5 g/l. ~he free calcium ion concentrations were then determined at intervals, with the following resul-ts:

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3~ C,1045 Ca'~~~ (~H) Com~ Time~ L ~ 1 min 2 mins Lf mins 15 mins A 30 2.1 1.9 2.0 2.1 2~0 B 30 12.0 7.6 4.6 3-o 1~3 C 3 15~0 14~0 14.0 14.0 14~0 D 30 12.0 9,o 5~8 3-5 1.4 These results show a marked benefit for composition A made , according to the invention.
XAMPIæS 2 ~0 6 . Six powdered deterge~t compositions including two control produc-ts E & ~ were prepared as follows:
E ~æ 2 EX 3 ~ ~x L~ Ex 5 ~ 6 Sodium alk~l benzene 28 28 28 28 28 28 28 sulphonate . Sodium orthophosph.ate 2.2 2~2 2.2 4~5 4.5 4.5 4.5 Sodium carbonate 0 15 30 0 10 25 15 15 Sodium bicarbonate ~ 5 Sodium alkaline ----~ 10O0------- ----------silicate ~odium sulphate 49O8 340819~8 47.5 .37~5 22.5 1705 I~Jater -----------~ to 100-------------~
~he detergency performance of these compositions were 20 compared a-t product concentrations of 2.5 g/l, calcium hardness of 15H (~rench), liquor to cloth ratio of 5:1 -:.......... and temperatuxe of 25C~ ~hree artificially soiled test cloths were used and -the detergency found b~ determining '; the change in light reflecta~ce before and after washi~g, with the following results- .
: ~est aloth ,(Increase In l~ht refle,ctance~
~est Cloth ~ .~est Cloth 0 Product E 2109 14~6 . 0.4 ~ample 2 ' Z3.8 19.0 2.3 ~; 30~ hxample 3 25-7 19.7 ' 3.9 ,: Product F ' 2308 14~3 0.2 ' ~ Example 4 26.2 , 2007 3~5 Example 5 27,.6 2107 5.8 ' ' Example 6 34.Q 23~Q 7- .
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`~ ' ' '' : ' ~:' ' - 12 - C.1045 ~ he benefit of having a hi~h carbonate con-ten-t toge-ther wi-th -the low o.rthophospha-te level in the composi-tions of the invention is readily apparent, compared wi-th the control products~
EXAMPIES 7 A~D 8 ~ he following formulations including four con-trols G to J were prepared:
In~redient %
G ~ 8 H I J
Sodium alkyl benzene sulphonate 28 28 28 28 28 28 ~odium orthophospha-te 4.5 4O5 4~5 7.0 - -Sodium carbonate - 30 10 ~0 30 10 Sodium percarbonate - - 2906 - - 29.6 ~odium alkaline silicate . 10 10 10 10 10 10 Sodium sulphate 47.517.5 7.915 22 12.4 Water to 100 ~ he de-tergenc~J performance of these compositions was investigated at product concentrations of 2.5 g/l, calcium . hardness of 15H (~rench), liquor to clo-th ratio of 5:1 and a tempG~rature of 25C~ Three artificuall~ soiled test cloths were used and the detergency fou~d by determini~g the change in light reflectance before and after washing~
with the following results:
est Cloth ~Increase in light reflectancel 25 ~ormulation est Cloth ~est Cloth B ~est Cloth C
G 28.1 21.2 6~4 7 30~7 22.6 8-5 8 31.1 22.8 8~6 H 31.0 22.5 8~8 :~ 3 . I . 26.2 18~8 5.5 J 26~4 18.4 5~7 ~he test cloths used in ~xample 2 to 8 were as follows:
~est Cloth A - ~ mixture of sebum fatty acids and carbon black impregnated into cotton-poplin~

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3~Z3~7 - 13 - C.1045 est Cloth ~ - A mix-ture of ground nut oil, indian ink, casein and iron oxide impregna-ted into cotton sheeting.
~est Cloth C - A mixture o~ bandy black clay, a nonionic detergent and a cationic detergent impre~nated into cotton cloth, ~ he per~ormance of the formulations of Examples 7and8 was`investigated at 60C, the other test conditions remaining the same, except that the test cloth was a tea stained cloth, ~he results were as follows:
,or~ulation Chan~e in reflectance ~x 7 0~1 Ex 8 4.9 EX~MPIæ 9 - Detergent bars were prepared according to-the following formulations: ` -~ ' ' . %
Ex 9 Control E
Sodium alkyl ~enzene sulphonate 28 28 Sodium orthophosphate - 4 Sodium carbonate 22 22 Calcite 30 35 Sodium sulphate 6 5 Water - 10 10 lhe bars were used to hand wash ~est Cloth C
~referred to abo~e) àt a li~uor to cloth ratio of 5 water hardness of 15H (~rench) and a wash temperature -of 25C. ~he test results were~
Formulation ~ Chan~e _ lect~
~x 9 ~ ~10.~
K ~ 7~2`

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An alkaline detergent composition for fabric washing comprising ( i) from about 10% to about 40% of a synthetic detergent surfactant selected from the groups consisting of anionic, nonionic, amphoteric and zwitterionic detergent surfactants and mixture thereof;
( ii) from about 10% to about 40% of an alkali metal carbonate;
(iii) from about 1% to less than 5% of an orthophosphate material selected from the group consisting of orthophosphoric acid and the ammonium, sodium or potassium salts thereof; and ( iv) not more than 5% of other phosphate builder salts, all percentages being by weight of the composition.

2. A composition according to Claim 1 wherein said orthophosphate material is selected from the group consisting of sodium and potassium orthophosphate salts.

3. A composition according to Claim 2, wherein said orthophosphate material is present in an amount of from about 1% to about 4.5% by weight of said composition.

4. A composition according to Claim 1, wherein said composition contains from about 0.2% to about 1.5% by weight of said composition of phosphorus in the form of said orthophosphate material.

5. A composition according to Claim 1, wherein said composition additionally contains from about 10% to about 50% by weight of said composition of a peroxygen bleach other than an alkali metal percarbonate.

6. A composition according to Claim 2, wherein said composition additionally contains one or more additives selected from lather depressants, enzymes, lather boosters, antiredeposition agents, alkaline buffers, fluorescent agents, perfumes, colourants and fillers.

7. A composition according to Claim 1, wherein said alkali metal carbonate is an alkali metal percarbonate.