CA1137384A

CA1137384A - Fabric washing process and detergent composition for use therein

Info

Publication number: CA1137384A
Application number: CA000363146A
Authority: CA
Inventors: Ronald M. Morris; John R. Samuel
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1979-10-26
Filing date: 1980-10-24
Publication date: 1982-12-14
Also published as: DE3064438D1; JPS5673164A; ZA806488B; BR8006871A; AU542093B2; EP0028894A1; EP0028894B1; AU6368980A; ATE4333T1

Abstract

ABSTRACT:-A process for washing fabrics includes the steps of contacting the fabrics with a liquor containing a detergent active compound and an orthophosphate and subsequently contacting the fabrics with a liquor containing a tripolyphosphate. The tripolyphosphate may be added to the orthophosphate-containing liquor or may be present in a separate liquor. In the former case the tripolyphosphate may be present from the start of the wash but in a form to delay its dissolution in the liquor, such as by being encapsulated, cogranulated or contained in a sachet. Delay times of about 5 minutes are disclosed. The method leads to reduced incrustation on fabrics.

Description

1~37384 - 1 - C.1057 FABRIC WASHING PROCESS A~D DE~ERGE~
CO~POSI~IOW ~OR USE ~HEREI~

he p~esent invention relates to fabric washing processes and to the compositions which are adapted for this purpose, using synthetic detergent active compounds together with phosphate detergency builders. ~ne invention concerns in particular fabric washing using detergent compositions which contain levels of the phosphate detergenc~ builders which can be lower than conventional phosphate builder levels, whilst still achieving good detergency results.
It is known to include tripolyphosphates as builders in detergent compositions. In U~ 4 113 644 (Ashcraft) there is described a detergent composition containing both orthophosphate and tripolyphosphate in addition to high levels of alkalimetal pyrophosphate, .. ~

~137384

- 2 - C.1057 ~ detergent dishwashing composition is known from GB 1 224 777 (Armour) which is intended for use at substantially neutral pH and which contains in addition to an acid orthophosphate, encapsulated sodium tripoly-phosphate with the obaect of providing good cleaningaction over an extended period of time~
It is also known to wash fabrics in two steps.
~hus GB 996 193 (Henkel) describes adding a first concent~ate to water to form a wash liquor and subsequently adding a second concentrate to the same liquor. By suitable choice of components in these concentrates, enhanced bleaching of fabrics can be obtained.
~he present in~ention on the other hand is concerned with low phosphorus containing compositions having enhanced building properties.
According to a first aspect of the invention there is provided a process for washing fabrics comprising the steps of:
( i) contacting the fabrics with a wash liquor containing a synbhetic detergent active compound and an alkali-metal or ammonium orthophosphate; and (ii) subsequently contacting the fabrics with a wash liquor containing a synthetic detergent active compound and an alkalimetal or ammonium tripoly-phosphate, each of said wash liquors having a pX
between about 8 and about 12 and each of said wash liquors containing substantially no alkalimetal pyro~hosphate .
~he process can be conducted if desired in two stages, or example using a prewash as step (i) and then a main wash as step (ii), the fabrics being substantially separated from the prewash liquor before being contacted with the main wash liquor. In this event there is often some carry-over of the ingredients in the pre-wash into the main wash, so that there is some _ 3 _ C.1057 benefit from the presence of residual alkalimetal ortho-phosphate in the main wash liquor. Many modern domestic washing machines are designed for sequential pre- and main washes, or the consumer may himself arrange the sequential washing.
Alternatively, the washing process can be conducted in a single stage, where the liquor used in step (i) remains in contact with the fabrics during step (ii).
~his can be achieved by including the tri-polyphosphate together with the orthophosphateand synthetic detergent compound in a single composition, but treating the former to delay its dissolution so that in step (i) it remains in an undissolved form, or by adding the tripolyphosphate to the wash solution later than the other ingredients. ~his can again be achieved manually or automatically. Dissolution of the tripoly-phosphate is desirably delayed for at least 15 seconds, preferably at least one and especially at least 5 to 30 minutes, or even more after dissolution of the bulk of the orthophosphate, to encourage maximum precipitation of calcium orthophosphate before addition of the former.
According to a second aspect of the invention there is provi~ed a detergent composition for carrying out such a method, comprising a synthetic detergent active compound,an lakalimetal or ammonium orthophosphate andan alkalimetal or ammonium tripol~phosphate characterised by means for delaying the solubility of said alkalimetal or ammonium tripolyphosphate when the composition is added to water to form a wash liquor, said composition yielding a pH
o between about 9 and about 11 when dissolved in 12H(Ca) water at ~0C and at a concentration of 0.1% w/v, and said composition containing subs'antially no alkalimetal pyrophosphate.
~he detergent composition may be in the form of two containers, the first container containing at least a part of said synthetic detergent active compound and - ~ - C.1057 the orthophosphate and the second container containing the alkallmetal or ammonium tripolyphosphate and optionally a further part of the synthetic detergent active compound. In use, the contents of the first container are released into water to form a wash liquor for step (i) of the process and subsequently the contents of the second container are released to form a wash liquor for step (ii) of the process.
~he delayed addition of the tripolyphosphate to the washing solution is advantageous in giving decreased deposition of inorganic phosphates on the washed fabric, compared with the simultaneous addition of the tripoly-~phosphate and orthophosphate. It is believed that this is due to the substantially complete precipitation of calcium orthophosphate by reaction with hard water before dissolution of the tripolyphosphate. lhis, in turn, appears to lead to decreased hydrolysis of the tripoly-phosphate, compared with the amount of hydrolysis which takes place when the water had not been pre-softened in this way; one o~ the products of hydrolysis is alkali metal or ammorium pyrophosphate which apparently causes high levels of inorg~n;c deposition on the washed fabric, and hence the control of the rate of hydrolysis of the tripolyphosphate as proposed leads to decreased fabric deposits~
~ he washing process of the invention can be accomplished manually, if desired, but is normally accomplished in a domestic or commercial laundry washing machine. he latter permits the use of higher wash

3 temperatures and alkalinity, and more effective agitation, all of which contribute generally to better detergency.
High wash temperatures (at least about 60C) and high alkalinity (over about pH 10) also particularly assist the precipitation of the calcium orthophosphate to achieve more effective water softening. However, any ~ash temperature between a bient end boiling mey be employed with any normal ~137384 - 5 - C.1057 degree of alkalinity (pH 8-12). ~he type of washing machine used, if any, is not significant.
It is preferred to accomplish the washing process in the joint presence of both the orthophosphate and the tripolyphosphate, but with the dissolution of the latter being delayed, as described above. This has the advantage of combining the water-softening action of both phosphates.
~his means, referring to the process of the invention, that the first aqueous solu~ion is used to prepare the second aqueous solution. An added advantage is that the detergent active compound used in both solutions can then be the same ;substance or mixture of substances.
It should be appreciated that when in aqueous solution in h æd water, the alkali metal or ammonium ortho-phosphate and tripolyphosphate will be present whollyor partially in the form of the calcium or magnesium salts, which are insoluble for the orthophosphates and soluble chelates in the case of the tripolyphosphate. But for convenience the phosphates will be referred to generally as bein~ in th~ ~1kali metal or ammonium salt form as appropria~e, as if the aqueous solutions were prepared with de-ionised water.
~ he detergent compositions used in the process of the invention may be either solid or liquid compositions.
Either ph~sical form can be used if the orthophosphate and tripolyphosphate are included in different compositions for separate addition to the wash liquor. Compositions in liquid form are suitable in particular for commercial laundry use, in which buIk supplies of aqueous orthophos-phate and tripolyphosphate solutions are available andare automatically dosed to the washing machines at the appropriate times in the wash cycle. But if the orthophos-phate and tripolyphosphate are included in a single composition, with the latter being treated to delay its solubility, the composition will normally be in solid form, e.g. as a powdered or granulated product.

- 6 - C.1057 ~ he invention includes processes for the preparation of such detergent compositions suitable for fabric washing according to the invention, by forming a detergent base powder containing a detergent active compound or compounds and optionally the alkalimetal orthophosphate, and admixing with the base powder any further orthophosphate and an alkalimetal or ammonium tripolyphosphate,treated to delay its dissolution in water.
Preferably the base powder is prepared by spray dryin~ in the normal way using conventional equipment and process conditions. However, other conventional techniques may be used for preparing the base powder containing the detergent active compound and usually the orthophosphate.
Other heat-sensitive ingredients may also be admixed with the base powder together with or separately from the treated alkali metal or Pmmonium tripolyphosphate,for example oxygen bleach co~pounds such as sodium perborate.
~ he alkali metal tripolyphosphate used in the compositions of the i~vent~on is preferably sodium tripolyphosphate, but if desired thg ~otassium or ammonium salts can be used. For convenience the term alkali metal tripolyphosphate is used below to include the sodium, potassium and ammoniumsalts~
~he alkali metal tripolyphosphates are generally represented as ha~in$ ula M20(MP3)3 or MsP301o where M is sodium~
potassium or ammonium.
If the tripolyphosphate is treated to delay its dissolution, for inclusion in a single composition with the orthophsophate, this ma~T be accomplished in the production of the tripolyphosphate or subsequen' l~o .
Specifically, the tripolyphosphates may be made with a large particle size or the tripolyphosphate may be coated or encapsulated with a slowly soluble material such as wax, nonionic detergent compounds,higher fatty acids or a protein such as gelati~. ~he rate of solubility of the tripolyphosphate ~5 may also be decreased by using them in partial calcium, zinc or other polyvalent salt form. ~wo or more of these - ` 1137384 treatrents may also be combined, so as to ~ive close con.rol over the solubility of the tripolyphosphate under the recommended washing conditions.
The rate of solubility of the polymer phosphate may also be controlled by granulating the tripolyphosphate with sodium silicate. Specifically, the granules may contain the tripoly-phosphate and an alkalimetal silicate having a M20:SiO2 ratio of from about 1:2 to about 1:3.75 wherein M is an alkalimetal, the granule being dried to a moisture content of less than 7%
by weight. A particularly useful granule of this type can be achieved by granulating 1 part of tripolyphosphate with 3 parts of sodium silicate having an Na20:SiO2 ratio of 1:2. The tri-polyphosphate-containing granule may also contain a portion of the synthetic detergent-active compound.
US 4 040 988 (Benson) describes granules formed by sequestering builders and alkalimetal silicates and may be referred to in this connection.
The delayed solubility of the tripolyphosphate may also be achieved by dosing the composition in a two-compartment sachet, the sachet being so constituted that when added to water the contents of the first compartment, namely the alkali-metal orthophosphate and at least some of the synthetic detergent active compound are released before the contents of the second compartment, namely the alkalimetal or ammonium tripolyphosphate and optionally a further part of the synthetic detergent active compound.
A sachet may be made from a first outer sheet of poly-ethylene film, a second outer sheet of acrylic bonded polyester/
viscose non-woven fabric and an inner sheet of thermally bonded polypropylene non-woven fabric, these three sheets ~eing heat-sealed together at the edges to define a sachet with two compartments. Before sealing the final - 8 - C.1057 edge, the first compartment between the two layers of - non-woven fabric may be filled with the orthophosphate and at least some of the synthetic detergent active compound. ~he second compartment may be filled with the alkalimetal or ammonium tripolyphosphate and optionally a further part of the synthetic detergent acive compound.
In use the contents of the second compartment are released after those of the first compartment because they must pass through the first compartment before entering the wash liquor.
~ he solution of the tripolyphosphate may also be delayed by coating or encapsulating the tripolyphosphate with a water-dispersible water-insoluble material or with a water-soluble material. Examples of such coating materials include fatty acids, alkanolamindes of fatty acids, glycerol esters of fatty acids, long chain hydrocarbon aliphatic alcohols, para~fin waxes, mineral oil, gelatin, sugar, non-ionic surface active agents, polycinylalcohol and sodium carboxymeth~lcellulose as described in U~ 3 847 830 (Williams) and G~ 1 242 247 (Unilever).
~he orthophosphate used is either potassium or preferabl~r sodium orthophosphate, as the latter is cheaper and more readil~ available. Ammonium orthophosphate may also be used, particularly if the composition is not made by spray drying. ~ormally the tri-alkali metal salts are used, but orthophosphoric acid or the di- or mono-alkalimetal salts, e.d. gisodium hydro~en orthophosphate or mono-sodium dih~drogen orthophospha~e could be used if 1:~37384 _ 9 - C.1057 desired in the production of the compositions. In the i~ latter event other more alkaline salts should also be present to maintain a high pH in the end product, i.e.
; with full neutralisation to the trialkali metal orthophos-5 phate salts. ~he use of a mixture of the monosodium dihydrogen and disodium hydrogen orthophosphates in the ratio of 1:~ to 2:3, especially about 1:2, is particularly ç advantageous, as such a mixture (known as kiln-feed) is made in the production of sodium tripolyphosphate and is readily 10 available.
~he orthophosphate can be used in the form of the anhydrous or hydrated salts, but in the former case , it is preferred to promote hydration during processing, e.g. by adding the anhydrous orthophosphate to a detergent 15 slurry and spray drying to form a base powder. ~he alkali metal pol~mer phosphates do not form hydrated salts as such, and are normally used in predominantly anhydrous form, but they are hygroscopic and tend to absorb atmospheric moisture.
~he amounts of salts used are expressed in anhydrous form.
. .

_ ~0 _ C.1057 ~ he total amounts of the essential tripolyphosphate and orthophosphate, and any other phosphates which may be present in the detergent compositions, are chosen according to the overall detergency builder level which is desired in the detergent compositions or according to the maximum permitted phosphorus content.
~ormally, when both the orthophosphate and tripolyphosphate are present in a single composition, the total phosphate builder level, which is preferably derived solel~ from the aLkali metal tripolyphosphate and orthophosphate, is between about 5/0 and about 50%~
preferabl~ about 10% to about 30% by weight of the composition, with an amount of about 2% to about 20% each of the tripolyphosphate and orthophosphate.
Preferably the amounts of the tripolyphosphate and orthophosphate are each from about 5%
to about 15%, especially about 5% to 10% by weight of the produc-t. ~he total amount of tripolyphosphate and ~ orthophosphate is preferably from about 20 10% to about 25~o~ especially about 15% to about 2~/o~
by weight of the composition.
It is generally preferred to have amounts of the orthophosphate and the tripoly-phosphate, within the ratio of from about 3:1 to about 1:3 especiall~ about 2:1 to about 1:2, parts by weight. Ihese ratios of tripolyphosphate to orthophosphate are particulæly suitable for detergent compositions used at relatively high product concentrations, i.e. 0.3% to 0.8% by weight as is common practice in Europe, especially in front-loading automatic washing machines, and where moderate levels o~
phosphates are allowed in the products, i.e. equivalent to 2% to 7,b P.
It is preferable that the only phosphate detergency builders used in the process of the i~vention should be the ~5 tripolyphosphate and orthophosphate.
.... . ..

~137384 ~ 1~ ~ C~1057 In particular, it is desirable to use no alkali metal, i.e.
sodium or potassium, pyrophosphates in the compositions as this tends to increase inorganic deposition as mentioned above.
Some pyrophosphate is generally found as impurities at low levels in other commercial aIkali metal phosphates, and some pyrophosphate may also be formed by hydrolysis of any polymer phosphate during processing, for example during slurry making. Hence, total absence of alkali metal pyrophosphate is generally unattainable in the detergent compositions. It is particularly preferred to have not more than about 5% especially not more than about 2.5% of alkali metal pyrophosphate present in the compositions, as at higher levels the amounts of inorganic deposits on the washing machine parts become significantly more noticeable.
~ ~~ However, some of the tripolyphosphate may be replaced b~ an alkalimetal or ammonium polymerphosphate such as is described in our copending application No (GB 7937167 Case ~o C.1052).
! 20 The process of the invention is necessarily accom~lished using synthetic anionic, nonionic, amphoteric or zwitterionic detergent active compound or mixture thereof. Detergent compositions normally include f~om about 2.5% to about 50%, preferabl~ about 5% to about 3~, and especially about 1C% to about 25% by weight of such iDb~redients. Many suitable detergent compounds are commerciallr available and are fully described in the litera-ture, for example in 'ISurface Active Agents and Detergents", Volumes I and II, by Schwartz, Perry & ~erch.
~he preferred detergent compounds which can be used are synthe~ic anionic and nonionic compounds. The former are usually water-soluble alkali metal salts of organic sulphates and sulphonates having aIkyl radicals containing from about 8 to about 22 carbon atoms, the term aIkyl being used to include the aI~yl portion o~ higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium `- 1137384 _ ~ _ C.1057 and potassium alkyl sulphates, expecially those obtained by sulphating higher (C8-C18) alcohols produced for example from tallow or coconut oil; sodium and potassium aIkyl (Cg-C20) benzene sulphonates, particularly sodium linear secondary alkyl (C10-C15) benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulphates and sulphonates,; sodium and potassium salts of sulphuric acid esters of higher (C8-C18) fatty alcohol-alkylene oxide, particularly ethylene oxide, reaction 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; aIkane monosulphonates such as those derived by reacting alpha-olefins (C8-C20) with sodium bisulphite and those der;ved from reacting paraffins with S02 and Cl2 and then hydrolysing with a base to product a ra~dom sulphonate; and olefin sulphonates, with term is used to describe the material made b~ re.acting olefins, particularly C10-C20 alpha-olefins, with S03 and then neutralising and hydrol~sin~ the reaction product. ~he preferred anionic detergent ^ompou~ds are sodium (C11-C15) alkyl benzene ; 25 sulphonates and sodium (C16-C18) alk~l sulphates.
Suitable nonionic detergent compounds which may be used include i~ particular the reaction products of compounds ha~ing a h~drophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or aIkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide Specific nonionic detergent compounds are al~yl (C6-C22) phenols-ethylene oxide condensates, generally 5 to 25 E0, i.e. 5 to 25 units of ethylene oxide per molecule, the condensation products of aliphatic (C8-C18) primary or secondary linear or branched alcohols with ethylene oxide, generally 6 to 30 ~0, and products made by condensation of ethylene oxide with the ~137384 reaction products of propylene oxide and ethylenediamine.
Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.
Mixtures of detergent compounds, for example mixed anionic or mixed anionic compounds may be used in the detergent compositions, particularly in the latter case to provide controlled low sudsing properties. This is beneficial for compositions intended for use in suds-intolerant automatic washing machines. We have also found that the use of some nonionic detergent compounds in the compositions decreases the tendency of insoluble phosphate salts to deposit on the washed fabrics, especially when used in admixture with some soaps as described below.
Amounts of amphoteric or zwitterionic detergent compounds can also be used in the compositions of the invention but this is not normally desired due to their relatively high cost.
If any amphoteric or zwitterionic detergent compounds are used it is generally in small amounts in compositions based on the much more commonly used synthetic anionic and/or nonionic detergent compounds. For example, mixtures of amine oxides and ethoxylatednonionic detergent compounds can be used.
Soaps may also be present in the detergent compositions of the invention, but not as the sole detergent compounds.
The soaps are particularlyuseful at low levels in binary and ternary mixtures, together with nonionic or mixed synthetic anionic and nonionic detergent compounds, which have low sudsing properties. The soaps which are used are the sodium, or less desirably potassium, salts of C10-C24 fatty acids. It is particularly preferred that the soaps should be based mainly on the longer chain fatty acids within this range, that is with at least half of the soaps having a carbon chain length of 16 or over. This is most conveniently accomplished by using soaps from natural sources such as tallow, palm oil or rapeseed oil, which can be hardened if desired, with lesser amounts of other shorter ` 1~37384 _ ~4 _ C.1057 chain soaps, prepared from nut oils such as coconut oil or palm kernel oil ~he amount of such soaps can be up to about 25% by weight, ~rith lower amounts of about 0.5% to about 5% being generally sufficient for lather control. Amounts of soap between about ~/o and about 2~/o~ especially between about 5% and about 15%~can advantageously be used to give a beneficial effect on detergency and reduced levels o~ incrustation.
Apart from the essential detergent active compounds and de-tergencybuilders,the detergent compositions used intheprocess of the inve~tion can contain any of t~e conventional additives in the amounts in which such materials are normally employed in fabric washing detergent compositions. Examples of these additives include lather boosters such as aIkanolamides, particularly the monoethanolamides derived from palm kernel fatty acids and coconut fatty acids, lather depressants such as alkyl phosphates, waxes and silicones, antiredeposition agents such as sodium carboxymethylcellulose and polyvinyl pyrrolidone optionally copolymerised with vinyl acetate, oxygen-releasing bleaching agents such as sodium perborate and sodium percar~onate, per-acid bleach precursors, chlorine-releasing bleaching agents such as trichloroisocyanuric acid and alka~li m~tal salts of dischloroisocyanuric acid, fabric softenin~ agen~s, inorganic salts such as sodium sulphate, sodium carbonate and magnesium silicate, and, usually present in very minor amounts, fluorescent agents, perfumes, enz~mes such as proteases and amylases, germicides ~nd colourants.
It is particularly beneficial to include in the detergent compositions an amount of sodium perborate, preferably between about 1~/o and ~/0, for example about 15% to about 3~/o, by weight. It has been ~ound that the bleaching action of sodium perborate is boosted under highly alkaline conditions which also give optimum detergency and building action from the orthophosphate. ~hus, it becomes possible to achieve improved bleaching propertles by using the same levels of sodium perborate as normal;
or decreased levels of sodium perborate can be used to give " ~37384 - 15 - C.1057 equal bleaching properties to those of conventional products with higher levels of perborate and sodium tripolyphosphate as the sole detergency builder. ~he latter option can also be used to further decrease the raw materials costs of the compositions, if a cheap filler is used in place of part of the sodium perborate.
It is desirable to include one or more antideposition agents in the detergent compositions of the invention, to decrease the tendency to form inorganic deposits on washed fabrics. It appears that the effective antideposition agents are materials which stabilise insoluble calcium orthophosphate particles and thereby inhibit their deposition onto the fabrics. ~he most effective anti-deposition agen~s are anionic polyelectrolytes, especially polymeric aliphatic carboxylates. ~he amount of any such antideposition agent can be from about 0.01% to about 10/o of the compositions, but is normally from about 0.1% to about 5% by weigh~, preferably from about O.~/o to about 2/o by weight of the compositions.
Specific preferred antideposition agents are the ~lkali metal or ~moniwm, preferably the sodium, salts or homo-and co-polymers of acrylic acid or substituted acrylic acids, such as so~iium polyacrylate, the sodium salt of copolymeth-acrylamidejacrylic acid and sodium poly-alpha-hydrox~acrylate, 25 salts of copoly ers of maleic anhydride with ethylene, acrylic acids vl~vl~ethylether allyl acetate or styrene,especially 1:1 copol-~mers, and optionally with partial esteri~ication of the carbox~l groups. Such copolymers preferably have relativel~
low molecular weights, eg in the range of about 1,000 to 50,0QO. Other antideposition agents include the sodium salts of polymaleic acid, polyitaconic acid and polyaspartic acid, phosphate esters of ethoxylated aliphatic alc~hols, poly-ethylene glycol phosphate esters, and certain phosphonates such as sodium ethane-1-hydroxy-~,1-diphosphonate, sodium ethylenediamine tetramethylene phosphonate, and sodium 2-phosphonobutane tricarboxylate. Mixtures of organic phosphonic acids or substituted acrylic acids or their salts `` 1~ 37384 _ 16 - C.1057 with pro-tective colloids such as gelatin may also be used.
~he most preferred antideposition agent is sodium poly-acrylate having a ~ of about 10,000 to 50,000, for example about 20,000 to 30,000.
It is also possible to include in the detergent compositions of the invention minor amounts, preferably not more than about 20% by weight, of other non-phosphate detergency builders or sequestrant builders. ~his is of particular benefit where it is desired to increase detergency whilst using particularly low levels of the e~sential alkali metal tripolyphosphate and alkali metal orthophos-phate builders, so as to achieve especially low phosphorus contents in the detergent compositions. Examples of such other detergency builders are amine carboxylates such as ~5 sodium nitrilotriacetate, sodium carbonate, sodium amorphous or crystalli~e aluminosilicate ion-exchange materials, sodium citrate and soap, which can function as a detergency builder, as discussed above. However, such other builder materials are not essential and it is a particular benefit of using the mixed alkali metal tripolyphosphate and orthophosphate that satisfactory detergency properties can be achieved at lower total phosphate levels than hitherto considered necessary without other detergency builders.
It is generally also desirable to include in the compositions an amount of an alkali metal silicate, particul~rly sodium ortho-, meta- or preferably neutral or alkaline silicate~ ~he presence of such alkali metal silicates at levels of at least about 1% and preferably from about 5% to about 15%, by weight of the composition, is ad~antageous in decreasing the corrosion of metal parts in washing machines, besides giving processing benefits and generally impro~ed powder properties. ~he more highly aIkaline ortho- and meta-silicates ~ould normally only be used at lower amounts within this range, in admixtu~e with the neutral or al~aline silicates.

"~ 1137384 _ ~7 _ C.1057 .. . . . ... . . . _ .. . . _ . . .. .
~ he compositions of the invention are required to be alkaline, but not too strongly aIkaline as this could result in fabric damage and also be hazardous for domestic usage.
In practice the compositions should normally give a pH of from 9 to 11 in use in aqueous wash solution. It is preferred in particular for domestic products to have a minimum pX of at least 9.25 and especially a pH of 9.5 or over, as lower pHs tend to be less effective for optimum detergency build;ng, and amaximum pH of ~0.5, as more highly aIkaline products can be hazardous if misused. The pH is measured a-t the lowest normal usage concentration of 0.1%
w/v of the product in water of 12H (Ca), (~rench permanent hardness, calcium only) at 50C so that a satisfactory degree of aLkalinity can be assured in use at all normal product concentrations.
The pH of the detergent compositions in use is contrclled by the amount of orthophosphate and any other aLkaline salts such as alkali metal silicate, sodium perborate and sodium carbonate present. The presence of such other alkaline salts, especially the alkali metal silicates, is particularly beneficial, because the alkalinity of the aIkali metal orthophosphate i5 diminished in hard water due to precipitation of the calcium salt. In addition the alkali metal tripolyphosphate is mcre stable and resistant to hydrolysis under moderatel~
alkaline conditions. ~he other ingredients in the aIkaline detergent compositions of the invention should of course be chosen for alkaline stability, especially the pH sensitive materials such as enzymes.
~0 The detergent compositions of the invention are prefer~ably made in particulate form, by admixtuIe of a spray dried base powder and treated tripoly-phosphate. However, if desired, the detergent compositions may be compressed or compacted into tablets or blocks, or ~5 otherwise treated for example by granulation, prior to packaging and sale. To~protect the compositions during ~tora~e it may be desirable to use moisture impermeable - 18 - C.1057 packaging for example in plastic or fabric sachets containing premeasured doses of the detergent compositions for washing machine usage.
The invention is illustrated by the following Examples in which parts and percentages are b~ weight except where otherwise indicated~

Detergency tests were accomplished to determine the effect of delayed addition of sodium tripol~phosphate, using a nominal formulation of:
%
~odium alkyl benzene sulphonate 6 Nonioni~ detergent compound 2 (C12 alcohol - 12 E0) Soap 3 Sodium tripolyphosphate 5 ~odiwm orthophosphate 11 Sodiu~ sulphate 25 Sodium silicate 10 Magnesil~ silicate SCMC
Sodium perborate 23 Water (and minor additives) to 100 added ~ith the other ingredients or after a specified dela~.
Terg~o-tometer tests were undertaken, using a 25 minute wash cycle wi~h a product concentration of 10g/1 in water at 95C and 22 German hardness. ~he level of inorganic deposi-tions (ash) wasmeasuredfor the cotton test cloths after 6 30 and 18 repeat wash cycles, using delays of 0,5,10 and 15 minutes after the other ingredients before addition of the sodium tripolyphosphate,with the following results:
,, . ~

~37384 - 19 - C.1057 Delay % ash (Mins) 6 washes 18 washes 0 1.6 4.1 0.6 1.8 0.5 1.6 0.5 1.4 ~ hese results show a marked reduction in the i~organic deposition caused by the delayed tripolyphosphate addition.
Further detergency tests showed that there was no significant difference in detergency caused by the delay, when using a variety of different standard test cloths.
~he tests were repeated on alarger scale in a Miele automatic washing machine using a product dosage of 200g in water of 22 German hardness, and the boilwash cycle in which heating ta~es 30 minutes and the boil continues for 20 minutes. ~he sodium tripolyphosphate was added after 0,15,30 or 40 minutes, with the following results on the inorganic depositions, which confirm the benefit of delayed addition.
% ash Dela~ 3 washes6 washes 9 washes 12 washes 0 2.1 4.2 6.3 8.2 1.4 2.8 4.4 6.2 3 1.1 2.4 3-6 4.7 25 40 -9 1.7 2.4 3.2 Detergency tests on varied test cloths in the same washes again showed slightly improved wash results for the delayed addition of -the sodium tripolyphosphate, but within the margin of experimental error.

Experiments were carried out in a Tergotometer to demonstrate the effect of tripolyphosphate on fabric incrustation. A detergent composition having the 5 following formulation was made up by mixing solutions.
Insredient % by weight Alkyl benzene sulphonate 6 Nonionic detergent active 2 Socium soap (70/30 coconut/
hardened tallow) 3 Sodium alkaline silicate 10 Sodium sulphate 15 Sodium chloride 9.5 Sodium orthophosphate, Sodium tripolyphosphate, Sodium polyacrylate and water balance Fabrics were washed using this composition to which orthophosphate, tripolyphosphate and polyacrylate were added as set out below. The wash conditions were 40FH wash water hardness (Ca:Mg 4:1), 30FH flood and hand rinse water hardness (Ca:Mg 4:1), wash temperature 90C, wash time 20 minutes, flood 2 minutes, rinse 5 minutes and product dosage 14 g per litre. The results achieved are set out in the following table.

,. .
~' ~.~37384 - 21 _ C.1057 h h a) ~
rt~ ~ o c~t ~ c~ ~ 0 . . .. . . . . o D ~ u~ ~ ~ ~ u~ K~
r\ o ~
rl 0 ~ o a) a) ~rl 0 0 cd h h o o CU ~ o o ~U

,'1 h ~ ~0 a) ~
a~ '0 ~
~^ ~
~ P ~P
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Claims

- 22 - C.1057 THE EMBODIMENTS OF THE IF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for washing fabrics characterised by comprising steps of:
( i) contacting the fabrics with a wash liquor containing a synthetic detergent active compound and an alkalimetal orammonium orthophosphate; and (ii) subsequently contacting the fabrics with a wash liquor containing a synthetic detergent active compound and an alkalimetal or ammonium tripoly-phosphate, each of said wash liquors having a pH
between about 8 and about 12 and each of said wash liquors containing substantially no alkali-metal pyrophosphate.

2. A process according to Claim 1, characterised by being carried out in two stages, the fabrics being substantially separated from the wash liquor used in step (i) before being contacted with the wash liquor used in step (ii).

3. A process according to Claim 1, characterised in that the wash liquor used in step (i) remains in contact with the fabrics during step (ii).

4. A process according to Claim 1, characterised in that step (ii) is carried out at least 15 seconds after step (i).

5. A process according to Claim 1, characterised in that said alkalimetal or ammonium tripolyphosphate is present in the wash liquor used in step (i) in an undissolved form.

- 23 - C.1057

6. A detergent composition for washing fabrics by a method according to Claim 1, comprising a synthetic detergent active compound, an alkalimetal or ammonium ortho-phosphate and an alkalimetal or ammonium tripolyphosphate characterised by means for delaying the solubility of said alkalimetal or ammonium tripolyphosphate when the composition is added to water to form a wash liquor, said composition yielding a pH of between about 9 and about 11 when dissolved in 12°H (Ca) water at 50°C and at a concentration of 0.1% w/v and said composition containing substantially no alkalimetal pyrophosphate.

7. A detergent composition according to Claim 6, characterised by a first container containing at least a part of said synthetic detergent active compound and said orthophosphate and a second container containing said alkalimetal or ammonium tripolyphosphate and optionally a further part of said synthetic detergent active compound.

8. A detergent composition according to Claim 7, characterised in that said first container and said second container are constituted respectively by a first compartment and a second compartment of a sachet, said sachet being so constituted that when added to water the contents of said first compartment are released before the contents of said second compartment.

9. A detergent composition according to Claim 6, characterised in that said means for delaying the solubility of said alkalimetal or ammonium tripolyphosphate is constituted by a slowly dissolving material with which said tripolyphosphate is granulated or encapsulated.

- 24 - C.1057

10. A detergent composition according to Claim 6, characterised by containing by weight:
from about 2.5% to about 50% of one or more synthetic detergent active compounds selected from anionic, nonionic, amphoteric and zwitterionic synthetic detergent compounds;
from about 2% to about 20% of said alkalimetal or ammonium orthophosphate;
from about 2% to about 20% of said alkalimetal or ammonium tripolyphosphate in such a form as to delay its solubility when the composition is added to water to form a wash liquor, the ratio by weight of said orthophosphate to said tripolyphosphate being from about 3:1 to about 1:3;
optionally not more than about 20% non-phosphate detergent builders or sequesterant builders;
optionally not more than about 25% soap; and optionally one or more ingredients selected from lather boosters, antiredeposition agents, oxygen-releasing agents, per-acid bleach precursors, chlorine-releasing bleaching agents, fabric softening agents, inorganic salts, fluorescent agents, perfumes, enzymes, germicides and colourants.