ES2361413T3 - WASH METHOD OF COLADA. - Google Patents

Abstract

A method for washing a wash loading cloth in a washing liquid in a washing machine, said washing liquid containing a surfactant material, wherein said method comprises the step of changing the ionic strength of the washing liquid by the addition of one or more ionic ingredients thereto during a single wash cycle, characterized in that during the single wash cycle no more than 10% by weight of the washing liquid is discarded from the washing machine and because the concentration of the surfactant material in the liquid Washing is constant during the wash cycle.

Description

Technical field

The present invention relates to a laundry washing method in a washing machine, in which the concentration of one or more ingredients during a washing cycle changes.

Background of the invention

Washing machines commonly operate on the basis of a cyclic program. For example, a typical wash will comprise a wash cycle, a rinse cycle and a spin cycle in which the washings are respectively washed, rinsed and dried by centrifugation. Normally there is a liquid waste between these respective cycles. It is known to provide a prewash cycle before the main wash cycle, when it is desired to clean heavily soiled articles. Again, there is normally a waste of the prewash liquid before the dosing of the main wash liquid and the execution of the wash cycle.

In prewash, the same laundry cleaning product is normally used as in the main wash. However, it is also known to provide prewash compositions for use in the prewash cycle alone or in combination with part of the main wash composition. These prewash products or additives are often formulated so that they particularly attack difficult types of dirt. When a prewash cycle is not used, stains can be pretreated, for example, by applying an undiluted detergent composition to the soiled area before washing the laundry load in the main wash cycle. However, the use of a prewash or pretreatment cycle requires extra time and energy. Therefore, there is still a need for an energy efficient laundry cleaning method that optimizes the cleaning capacity of economical cleaning products.

WO 03/080916 describes a washing method in a washing machine, in which the laundry load is wetted efficiently and conveniently. The washing method described in this document includes the steps of (1) introducing the laundry load into the washing chamber of the washing machine, (2) supplying the washing water to the drum so that the water level increases by one stage to another and (3) repeatedly wet the laundry load. In addition, US-A-4,555,019 describes a method for washing a laundry load in a washing liquid in a washing machine, in which a first concentrated aqueous washing liquid is distributed over the laundry load and subsequently the rinse liquid is added (for example, fresh water). It can be seen that in these two prior art methods, the concentration of detergent material in the wash water in the wash chamber is significantly reduced.

On the other hand, US-2003/0182732 describes a portable self-included device for dosing and / or supplying a detergent composition in a device for treating fabrics. In addition, JP-6079092 and JP-5123489 describe methods for refining water using electrolysis. In addition, document UDS-A-5,965,505 may be mentioned, a document describing a detergent composition containing a heavy metal ion sequestrant and an organic peroxyacid bleaching system, which is provided to delay release to a washing system. of said bleaching system.

In addition, GB 2,313,603 A describes a detergent composition for use in laundry and dishwashing methods, in which methods are provided for delaying the release of an alkalinity system in relation to the release of a cationic ester surfactant.

It has now been discovered that in a single wash cycle, a change in the content of the washing liquid can optimize the cleaning capacity of the washing liquid.

The present invention consists in changing the ionic strength of the washing liquid during the washing cycle, whereby the concentration of surfactant in the washing liquid is kept substantially constant during the washing cycle.

Although theoretical links are not desired, this is supposed to exert an influence on the interaction between the stain and the surfactant (or a mixture thereof) making it possible to suppress a wide variety of stains.

Definition of the invention

Consequently, the present invention provides a method for washing a laundry load in a washing liquid in a washing machine, said liquid containing a surfactant material, in which during a single washing cycle, not more than 10% by weight of the Washing liquid is discarded from the washing machine, and in which the concentration of the surfactant material in the washing liquid is constant during the washing cycle and in which said method comprises the step of changing the ionic strength of the washing liquid by adding of one or more ionic ingredients to miso during the wash cycle.

In relation to the present invention, the washing machine in which the method of the invention is carried out is intended to be a common European washing machine for laundry loads.

Detailed description of the invention

Washing cycle

Contrary to when there are separate prewash and wash cycles, in the context of the present invention, "a single wash cycle" is a wash regime during which a substantial amount of wash liquid is retained, that is, It is not discarded. Preferably, this is done using two separate time phases, respectively, during which the ionic strength is different from one another. During the complete wash cycle, particularly during the change from the first phase to the second phase in that wash cycle, a part of the liquid may be discarded but will not be more than 10%, preferably not more than 1% by weight of the washing liquid and, most preferably, substantially no washing liquid will be discarded abroad.

The ionic strength of the washing liquid can be gradually changed during all or part of the washing cycle or it can change more abruptly between at least a first phase and a second phase of the cycle. The change in ionic strength is deliberately effected by controlled dosing of additional materials. Due to the nature of this procedure to change the ionic strength, an "abrupt" change may actually take place at some point, but the slope of the ionic concentration curve versus time will preferably be greater than in a period of gradual change, as stated above.

The ionic strength of the liquid is different in the first phase compared to the second phase. One way in which this can be done, as described in more detail later in the present specification, may be through the use of a delayed release formulation. However, in the initial part of any wash cycle, there is a first dissolution and / or dispersion of the laundry cleaning composition until an equilibrium concentration is reached. This period of constitution will be ignored and the ionic strength of the washing liquid during the first phase is the one after the initial dispersion / dissolution and the achievement of equilibrium. Then the second phase is initiated by a functional change by adding one or more ionic ingredients, with dispersion / dissolution of any of these additives to achieve a new ionic equilibrium force.

The addition of this ingredient or ingredients to change the ionic strength in order to reach a second phase can be done by dosing from a machine-attached dosing device, recycling at least part of the washing liquid through an external dosing device and bringing it back to the machine or by using a delayed-release formulation (for example, a temperature-sensitive delayed-release formulation whereby a controlled increase or decrease in the temperature of the liquid initiates the release of (or of) the ingredient ( s) additive (s)). Preferably, a delayed release formulation is used to change the ionic strength.

As a consequence of the addition of one or more ionic ingredients, the ionic strength in the washing liquid in the second phase is greater than in the first phase. The first phase could be considered as a beginning for the time to reach a substantial balance of the ionic species in the liquid and to end the action of initiating a change of ionic strength during the second phase. The second phase begins at the moment when a substantial new balance of the ionic strength is reached and ends with the start of an additional change to alter the ionic strength again or to discard the washing liquid before a rinse cycle. If more than two phases are used, their start and end is indicated as for the second phase. In any case, any phase independently lasts preferably from 2 to 60 minutes, more preferably from 2 to 30 minutes, even more preferably from 3 to 20 minutes and most preferably from 4 to 15 minutes. However, as mentioned above, the present invention does not necessarily include the use of discrete phases and gradual changes in ionic strength are also possible.

The ionic strength of the washing liquid depends on the amount and types of salt (s) soluble in water in the detergent product applied and dissolved in the liquid. The use of a variable concentration of salts, alone and optionally in combination with temperature changes has been found to improve suppression, or even reduce the need for higher temperatures. Therefore, it contributes to a global energy saving in the washing procedure.

Although in principle the present invention can be carried out at any desired temperature, most preferably the washing liquid during the ionic force variation is in the temperature range, for most of the time from 5 ° C to 100 ° C, more preferably from 5 ° C at 60 ° C, still more preferably from 5 ° C to 38 ° C and most preferably from 10 ° C to 30 ° C. However, as indicated above, the separated phases can in principle generally be carried out at temperatures different from each other.

An ion is an atom or group of atoms that is not electrically neutral, but instead carries a positive or negative charge, as a result of the loss or gain of an electron. In solution, the total ion concentration is defined as:

222

Ionic force (in moles per liter or M) = IS = ½ x (m1Z1 + m2Z2 + m3Z3 + ...),

in which m1, m2, m3 ... represent the concentration in moles of various ions in the solution and Z1, Z2, Z3 ... are their respective charges.

For example, using this, the IS of a 0.1 M solution of potassium nitrate (KNO3) is calculated as follows:

+ -22

mK and mNO3 = 0.1.Portanto, IS = ½x (0.1x1 + 0.1x1) = 0.1M.

Similarly, that of a 0.1 M solution of sodium sulfate (Na2SO4) is calculated using: mNa + = 0., 2 and

-2 22

mSO4 = 0.1.Portanto, IS = 1/2 x (0.2X1 + 0.1X2) = 0.3M.

The ionic strength is measured by measuring the conductivity of a diluted concentration of ions and taking into account the respective activity coefficients, that is, 0.9 or more for most of the mentioned salts applied to detergent products in the range of concentrations of 0.001 M to 0.01 M concentration. The activity coefficient gradually decreases at higher concentrations.

Normal salts include sodium, potassium or ammonium salts of sulfate, triphosphate, phosphate, chloride, citrate, carbonate, percarbonate, perborate, silicate, natural soaps, acetates, aluminosilicates (including zeolites), nitrile triacetates, alkyl sulphonates (including alkylbenzene) -sulfonate) or alkyl sulfates (including alkylethoxy- or alkylpropoxy sulfates) and mixtures thereof. Many of these materials are normal ingredients in laundry wash compositions, as will be described in detail later. In special cases magnesium salts of these materials can also be used.

A preferred list of salts comprises the sodium or magnesium salts of sulfate, carbonate, citrate, percarbonate, perborate, silicate, natural soaps and zeolite. However, the ionic strength of the washing liquid is mainly determined by salts that are easily soluble in water at the relevant temperature of the washing liquid.

The ionic strengths of the solutions of conventional washing liquids depend on the composition of the product in question and its dosage proportions. Additionally, the different forms of low bulk density products, concentrated or high bulk density powders, tablets, liquids, etc.) as well as the particular type in a format (for example, for energetic or dedicated washing liquids or colored) have different compositions of dissociable salts and, therefore, represent a wide range of ionic forces in the washing liquids in practice. Approximately speaking, washing liquids for single-phase isotropic liquids for delicate materials, as well as non-soapy detergent bars (NSD) provide low ionic strength (for example, 0.001 M to 0.03 M), modern Zeolite detergency builder powders of high bulk density provide a moderate ionic strength (for example, 0.02 M to 0.1 M) and low density phosphate builder detergent powders provide a high ionic strength (for example, 0.06 M to 0.2 M). The dosage of product by washing also varies and this contributes to the range of ionic forces that result from different types of products. The moderate ionic strengths of high bulk density powders constitute a significant cause of their inconvenience in the suppression of specific spots compared to traditional lower bulk density powders that have much higher ionic strengths. In addition, the latter are conventionally dosed at higher rates.

The ionic strength in the first phase is preferably from 0.001 to 0.06, more preferably from 0.002 to 0.04, still more preferably from 0.003 to 0.3, and, most preferably, from 0.005 to 0.02 M. In the case of the second phase in which the washing liquid has a relatively higher ionic strength, its ionic strength is preferably 0.01 to 0.5, more preferably 0.02 to 0.03, even more preferably 0 , 03 to 0.2 and, most preferably 0.04 to 0.15 M. It will be appreciated that in some cases, the respective intervals for the two phases overlap. However, it is a requirement that the actual values be different between the two phases during the whole or at least part of the respective time periods of those phases.

Washing liquid

The washing liquid contains a surfactant material whose concentration is substantially constant during the washing cycle. This means that the change in said concentration during the wash cycle is less than 10%, preferably less than 5%.

Anionic surfactants

Preferably, the washing liquid comprises at least one anionic surfactant. Preferably, in either or both phases, its concentration is 0.1 g / 10 g / l, more preferably 0.3 g / 4 g / l, even more preferably 0.4 to 2 g / l. For example, one or more alkylbenzene sulphonates, alkyl sulphonates, primary and secondary alkyl sulfates (in the form of free acids and / or salts) can be selected. The total amount of anionic surfactant can be from 0.001% to 75% by weight of the added composition.

A composition according to the present invention may contain, for example, from 0.1% to 70%, preferably from 1% to 40%, more preferably from 2% to 30%, especially from 3% to 20% of alkylbenzene acid surfactant. -sulfonic acid (in the form of free acid and / or salt) or a primary alcohol sulfate surfactant

or a mixture of these two in any relationship.

When it is desired to increase calcium tolerance, then any anionic surfactant in the composition may comprise (preferably at a level of 70% w or more of the total anionic surfactant) or consist only of one or more calcium-tolerant non-soap anionic surfactants.

As cited herein, an "calcium tolerant" anionic surfactant is one that does not precipitate at a surfactant concentration of 0.4 g / l (and at an ionic strength of a 1: 1 0.040 M salt solution) with a calcium concentration of up to 20º FH (degrees of French hardness) that is, 200 ppm of calcium carbonate.

A further preferred class of non-soapy calcium-tolerant anionic surfactants for use in the compositions of the present invention comprises alpha-olefin sulfonate.

Another preferred class of calcium-tolerant anionic surfactants comprises the branched medium chain materials described in WO-A-97/39087, WO-A-97/39088, WO-A-97/39089, WOA-97/39090, WO-A-98/23712, WO-A-99/19428, WO-A-99/19430, WO-A-99/19436, WO-A-99/19437, WOA-99/19455, WO-A- 99/20722, WO-A-99/05082, WO-A-99/05084, WO-A-99/05241, WO-A-99/05242, WOA-99/05243, WO-A-99/05244 and WO-A-99/07656.

Still, another class of calcium-tolerant anionic surfactants comprises alkyl ether sulfates (ie, alkoxylated alkyl sulfates).

Other calcium-tolerant anionic surfactants suitable for use in combination comprise alpha-olefin sulfonate and alkyl ether sulfate in a weight ratio of 5: 1 to 1:15.

Other anionic calcium tolerant surfactants that can be used are alkyl ethoxycarboxylate surfactants (eg, Neodox (registered trademark) of Shell), fatty acid ester sulphonates (eg, FAES MC-48 and ML-40). Stepan), alkyl-xylene-or toluene sulphonates, dialkyl sulphosuccinates, alkyl-amindo sulfates, sorpholipids, alkyl glycoside sulfates and alkali metal salts (eg sodium) of saturated or unsaturated fatty acids.

Still, other suitable anionic surfactants in addition to the calcium-tolerant anionic components are known to those skilled in the art. Examples include primary and secondary alkyl sulfates, particularly C8-C15 alkyl primary sulfates and dialkyl sulphosuccinates. Sodium salts are generally preferred.

Soaps

Optionally, a soap may also be present in either or both phases in the washing liquid. Preferably, the concentration is from 0.01 g / l to 10 g / l, more preferably from 0.03 g / l to 4 g / l and most preferably from 0.05 g / l to 2 g / l. Suitable soaps include those that have a length that varies in the range of C12 to C20, mainly saturated and optionally contain limited levels of 1 or 2 unsaturated bonds and derivatives of natural oils and fats such as: tallow (hydrogenated or not hydrogenated), coconut or palm kernel seed.

In a solid formulation, the amount of optional soap is preferably 0.1% to 10%, more preferably 0.1% to 5% by weight of the composition. In liquid compositions, the optional soap level is preferably 0.1% to 20%, more preferably 5% to 15% by weight of the composition.

Other optional surfactants

Other optional surfactants include non-ionic surfactants, cationic surfactants (for the improvement of detergency and / or softness of the fabrics), amphoteric and hybrid ion surfactants.

If desired, the non-ionic surfactant can also be included in either and not in the two phases. Preferably, the concentration will be 0.1 g / l to 10 g / l, more preferably 0.3 g / l to 4 g / l and most preferably 0.4 g / l to 2 g / l. The amount of these materials, in total, is preferably from 0.01% to 50%, preferably from 0.1% to 35%, more preferably from 0.5% to 25%, still more preferably from 0.7% to 20%, even more preferably from 0.8% to 15%, especially from 1% to 10% and even more especially from 1% to 7% by weight of the composition.

Preferred non-ionic surfactants are ethoxylated aliphatic alcohols having an average degree of ethoxylation of 2 to 12, more preferably 3 to 10. Preferably, the aliphatic alcohols are C8C16, more preferably C10-C15.

The branched, non-ionic, medium chain branched non-ionic components described in WO-A98 / 23712 are another class of suitable non-ionic surfactants.

Other suitable non-ionic and non-ethoxylated surfactants include alkyl polyglycosides, glycerol monoethers and polyhydroxyamides (glucamide).

Optionally, a composition according to the present invention may comprise from 0.05% to 10%, preferably from 0.1% to 5%, more preferably from 0.25% to 2.5%, especially from 0.5% to 1 % by weight of a cationic surfactant.

Suitable cationic fabric softening compounds are substantially water-insoluble quaternary ammonium materials comprising a single long alkyl or alkenyl chain having an average chain length greater than or equal to C20 or, more preferably, compounds comprising a head group polar and two alkyl or alkenyl chains having an average chain length greater than or equal to C14. Preferably, fabric softening compounds have two long chain alkyl or alkenyl chains each having an average chain length greater than or equal to C16. Most preferably, at least 50% of the long chain alkyl or alkenyl groups have a chain length of C18 or more. It is preferred that the long chain alkyl or alkenyl groups of the fabric softener compound are predominantly linear.

Quaternary ammonium compounds having two long chain aliphatic groups, for example, distearyl dimethyl ammonium chloride and di (hydrogenated tallow alkyl) dimethyl ammonium chloride, are widely used in commercially available rinse conditioning compositions. Other examples of these cationic compounds can be found in the publication "Surfactants Science Series" volume 34 ed. Richmond 1990, volume 37 ed. Rubingh 1991 and volume 53 eds. Cross and Singer 1994, Marcel Dekker Inc. New York.

It is also possible to include certain cationic mono-alkyl surfactants that can be used for their detergency. Cationic surfactants that can be used for these purposes include quaternary ammonium salts of the general formula R1R2R3R4N + X- in which the R groups are long or short hydrocarbon chains, usually alkyl, hydroxyalkyl or ethoxylated alkyl groups and X is a counterion (for example , compounds in which R1 is a C8-C22 alkyl group, preferably a C8-C10 or C12-C14 alkyl group, R2 is a methyl group and R3 and R4, which may be the same or different are methyl or hydroxyethyl groups) ; and cationic esters (for example, choline esters).

Detergency builders

In either or both phases, the washing liquid also very often contains one or more detergency builders. Detergency builders may be considered to be divided into two classes, namely those that are relatively soluble at the relevant temperature (s) of the washing liquid such as carbonates, phosphates (including orthophosphates and triphosphates, being a common term for one of the latter the "sodium tripolyphosphate"), citrates, bicarbonates, etc. which can contribute significantly to the ionic strength of the washing liquid. On the other hand, the second class includes relatively insoluble detergency builders that do not contribute much to the ionic strength, for example, aluminosilicates (zeolites), silicates, etc.

For water soluble types, the total amount can be deducted from the preferred ranges mentioned above for ionic forces that arise from water soluble salts.

The concentration of water-insoluble detergency builders will preferably be 0.01 g / 10 g / l, more preferably 0.1 g / 4 g / l and most preferably 0.5 g / l 2 g / l. The total amount of detergency builder in the compositions will normally vary in the range of 1% to 80% p, preferably 2% to 60% p, more preferably 4% to 30% by weight of the total composition.

Inorganic detergency builders that may be present include soluble detergency builders such as sodium carbonate, if desired in combination with a crystallization seed for calcium carbonate, as described in GB-A-1,437,950 and sodium bicarbonate; insoluble crystalline and amorphous aluminosilicates, for example, zeolites as described in GB-A-1,473,201, amorphous aluminosilicates as described in GB-A

1,473,202 and mixed crystalline / amorphous aluminosilicates as described in GB-A1,470,250; and layered silicates as described in EP-A-164,514. Soluble inorganic phosphate builders, for example, sodium orthophosphate, sodium pyrophosphate and sodium tri (poly) phosphate (STP) are also suitable for use in this invention. In this context "soluble" and "insoluble" are relative terms.

The compositions of the invention preferably contain an alkali metal aluminosilicate detergent builder, preferably sodium. Sodium aluminosilicates can generally be incorporated in amounts of 10 to 70% by weight (anhydrous base), preferably 20 to 50% p.

When the aluminosilicate is a zeolite, preferably the maximum amount is 30% by weight.

The alkali metal aluminosilicate can be crystalline or amorphous or mixtures thereof, has the general formula: 0.8-1.5 Na2O · Al2O3 · 0.8-6 SiO2.

These materials contain some bound water and they need to have a calcium ion exchange capacity of at least 50 mg Ca / g. Preferred sodium aluminosilicates contain 1.5-3.5 SiO2 units (in the above formula). Both amorphous and crystalline materials can be easily prepared by reaction between sodium silicate and sodium aluminate, as is widely described in the literature. The ion exchange exchange builders of suitable crystalline sodium aluminosilicates are described, for example, in GB-A-1,429,143. Preferred sodium aluminosilicates of this type are commercially available and well-known zeolites A and X and mixtures thereof.

The zeolite may be the commercially available zeolite 4 A, which is currently widely used in laundry detergent powders. However, according to a preferred embodiment of the invention, the zeolite detergency builder incorporated in the compositions of the invention is maximum aluminum zeolite P (MAP zeolite) as described and claimed in EP-A-384,070. The zeolite MAP is defined as an alkali metal aluminosilicate of the zeolite P type having a ratio of silicon aluminum that does not exceed 1.33, preferably in the range of 0.90 to 1.33 and, more preferably in the range of 0 , 90 to 1.20.

Especially preferred is zeolite MAP having a silicon to aluminum ratio that does not exceed 1.07, more preferably about 1.00. The calcium binding capacity of zeolite MAP is generally equivalent to at least 150 mg of CaO per g of anhydrous material.

Organic detergency builders that may be present include polycarboxylate polymers such as polyacrylates, acrylic / maleic copolymers and acrylic phosphinates; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, mono-, di- and tri-succinates of glycerol, carboxymethyloxysuccinates, carboxymethyloxy-malonates, dipicolinates, hydroxyethyliminodiacetates, alkyl and alkenylmalonates and succinates and salts of sulfonated fatty acids. This list is not intended to be exhaustive.

Especially preferred organic detergency builders are citrates, suitably used in amounts of 2 to 30% p, preferably 5 to 25% p, and acrylic polymers, more especially acrylic / maleic copolymers, suitably used in amounts of 0.5 to 15% p, preferably 1 10% p.

Both inorganic and organic detergency builders are preferably present in the form of alkali metal salt, especially sodium salt.

Whiteners

In either or both phases, the washing liquid may also suitably contain a bleaching system. The total concentration of all bleach or all bleaching components is preferably from 0.001 g / l to 10 g / l, more preferably from 0.1 g / l to 1 g / l. The fabric washing compositions may desirably contain peroxygen bleaching agents and their precursors, for example, inorganic persalts or organic peroxyacids, capable of producing hydrogen peroxide in aqueous solution.

Peroxygen bleaching agents include peroxygen bleaching compounds that are capable of producing hydrogen peroxide in an aqueous solution. These compounds are well known in the art and include hydrogen peroxide and alkali metal peroxides, bleaching compounds of organic peroxides such as urea peroxide and bleaching compounds of inorganic persalts such as perborates, percabonates, alkali metal perfosphates and the like. Mixtures of two or more of these compounds may also be suitable.

Preferred peroxygen bleaching agents include a peroxygen bleach selected from the group consisting of perborates, percarbonates, peroxyhydrates, peroxides, persulfates and mixtures thereof. Specific preferred examples include: sodium perborate, commercially available in the form of mono- and tetrahydrates, sodium carbonate-peroxyhydrate, sodium pyrophosphate-peroxyhydrate,

5 urea peroxide and sodium peroxide. Particularly preferred are sodium perborate tetrahydrate and, especially, sodium perborate monohydrate.

Sodium perborate monohydrate is especially preferred because it is very stable during storage and yet it still dissolves very quickly in the bleaching solution. Perch

Sodium bonate may also be preferred for environmental reasons.

Its amount in the composition of the invention will usually be in the range of about 1.35% by weight, preferably 5-25% by weight. One skilled in the art will appreciate that these amounts may be reduced in the presence of a bleaching precursor, for example, N, N, N ’, N’-tetraacetyl

15 ethylene diamine (TAED).

Another suitable hydrogen peroxide generating system is a combination of C1-C4 alkanol oxidase and a C1-C4 alkanol, especially a combination of methanol oxidase (MOX) and ethanol or glucose oxidase (GOX) and glucose.

The alkyl hydroperoxides are another class of peroxygen bleaching compounds. Examples of these materials include cumene hydroperoxide, t-butyl hydroperoxide and hydroperoxides derived from unsaturated compounds, such as unsaturated soaps.

Additionally, compounds useful as oxygen bleach include salts of superoxides, such as potassium superoxide or peroxide salts, such as disodium peroxide, calcium peroxide or magnesium peroxide.

Organic peroxyacids may also be suitable as the peroxy bleach compound 30. These materials normally have the general formula:

image 1

wherein R is an alkylene or substituted alkylene group containing from 1 to about 20 carbon atoms optionally having an internal amide bond; or a substituted phenylene or phenylene group; and Y is hydrogen, halogen, an alkyl, aryl, aromatic or non-aromatic imido group, a COOH group or a

35 group

image 1

(which provides di (peroxyacids)) or a quaternary ammonium group.

Normal monoperoxy acids useful in the present invention include, for example:

(i)

peroxybenzoic acid and peroxybenzoic acids substituted in the ring, for example, peroxy-alfanaphthoic acid or m-chloroperoxybenzoic acid;

(ii)

aliphatic, substituted aliphatic and aryl-alkyl monoperoxy acids, for example, peroxylauric acid, peroxystearic acid, 4-nonylamino-4-oxoperoxybutyric acid and N, N-phthaloylaminoperoxy-caproic acid (PAP); Y

(iii) 6-octylamino-6-oxo-caproic acid;

(iv)

Magnesium monoperoxophthalate-hexahydrate, available from Interox;

(v)

6-nonylamino-6-oxoperoxicaproic acid (NPAA);

(saw)

Phthaloylimidoperoxicaproic acid. Typical diperoxy acids useful in the present invention include, for example:

(vii)

1,12-diperoxydodecanedioic acid (DPDA);

(vii)

1,9-diperoxyazelaic acid;

(viii) deperoxytetradecanedioic acid;

(ix)

diperoxyhexadecanedioic acid;

(x)

diperoxybutyl acid; diperoxisebasic acid and diperoxyisophthalic acid;

(xi)

2-decyldiperoxybutane-1,4-dioic acid; Y

(xii) 4,4’-sulfonylbisperoxybenzoic acid.

Also suitable are inorganic peroxyacid compounds such as, for example, potassium monopersulfate (MPS). If organic or inorganic peroxyacids are used as the peroxygen compound, their amount will normally be in the range of about 2-10% by weight, preferably 48% by weight.

Peroxyacid bleaching precursors are known and widely described in the literature, as in British Patents 1,003. 310 and 1,519. 351, and documents EP-A-185,522, EP-A174,132, EP-A-120,591, and US-A-3,332,882, US-A-4,128,494, US-A-4,412,934 and US-A -4,675,393.

Another useful class of peroxyacid bleaching precursors is that of cationic peroxyacid precursors, that is, of substituted quaternary ammonium, as described in US-A4,751,015, US-A-4,397,757, EP-A- 284292 and EP-A-331,229. Examples of peroxyacid bleaching precursors of this class are:

2- (N, N, N-trimethyl-ammonium) ethyl-4-sulfonylcarbonate; as described in US-A-4,751,015; N-octyl-N, N-dimethyl-N10-carbophenoxy-decyl ammonium chloride (ODC);

and N, N, N-trimethyl ammonium toluyloxybenzene sulphonate.

An additional special class of bleaching precursors is formed by cationic nitriles as described in EP-A-458,396 and EP-A-464,880.

Any one of these peroxyacid bleaching precursors may be used in the present invention although some may be more preferred than others.

Of all the above classes of bleaching precursors, preferred classes are ethers that include acyl phenol sulphonates and acyl alkyl phenol sulphonates; acyl amides and quaternary ammonium substituted peroxyacid precursors including cationic nitriles.

Examples of such preferred peroxyacid bleach precursors or activators are sodium 4-benzoyloxybenzene sulphonate (SBOBS); N, N, N ’, N’-tetraacetyl-ethylene-diamine (TAED); Sodium 1-methyl-2-benzoyloxybenzene-4-sulphonate; Sodium 4-methyl-3-benzoyloxy-benzoate, SSPC; trimethyl ammonium toluyloxybenzene sulphonate, sodium nonanoyloxybenzene sulphonate (SNOBS); Sodium 3,5,5-trimethyl-hexanoyl-oxybenzenesulfonate (STHOBS) and substituted cationic nitriles.

Each of the foregoing precursors can be applied in mixtures, for example a combination of TAED (hydrophilic precursor) with more hydrophobic precursors, such as sodium nonanoyloxybenzene sulphonate.

Alternatively, aromatic aldehydes and dioxygen compounds can be applied as a peroxy acid precursor, as described in WO 97/38074.

The precursors can be used in an amount up to 12%, preferably 2-10% by weight of the composition.

Other classes of bleaching precursors for use in the present invention are found in WO 0015750 and WO 9428104, for example, 6- (nonanamidocaproyl) oxybenzene sulphonate. See WO 0002990 for imido-cyclic bleaching activators.

The precursors can be used in an amount up to 12%, preferably 2-10% by weight of the composition.

The bleaching composition of the present invention has a particular application in detergent formulations, especially in laundry cleaning. Consequently, in another preferred embodiment, the present invention provides a detergent bleaching composition comprising a bleaching composition as defined above and additionally a material with surface activity, optionally in conjunction with a detergency builder.

Also useful as bleaching agents in the compositions according to any aspect of the present invention are any of the organic bleaching catalysts, oxygen transfer agents or their precursors. These include the compounds themselves and / or their precursors, for example,

5

10

fifteen

twenty

25

30

35

40

any ketone suitable for the production of dioxirans and / or any of the analogs containing heteroatoms of dioxorane or dioxorane precursors, such as sulfonimines R1R2C = NSO2R3 (EP 446 982 A) and sulfonyloxaziridines, for example.

image 1

EP 446,981 A. Preferred examples of these materials include hydrophilic or hydrophobic ketones, especially used in conjunction with monoperoxysulfates to produce dioxirans in situ and / or the imines described in US 5,576,282 and the references described therein. Oxygen bleaching agents preferably used in conjunction with these oxygen transfer agents or precursors include percarboxylic acids and salts, percarbonic acids and salts, peroxymonosulfuric acids and salts and mixtures thereof. See also documents US-A-5,360,568, US-A

5,360,569 and 5,710,116.

Transition metal bleaching catalysts are well known in the art. Various classes based especially on transition metal complexes of cobalt, manganese, iron and copper have been described. Most of these bleaching catalysts are claimed to produce hydrogen peroxide or peroxyacid activation, it is also described that certain classes of compounds provide bleaching of stains by means of atmospheric oxygen.

One type of manganese-containing bleaching catalysts includes the manganese-based complexes described in US Pat. 5,246,621 and U.S. Pat. 5,244,594. Preferred examples of

IV III

these catalysts include [Mn2 (µ-O) 3 (1,4,7-trimethyl-1,4,7-triazacyclononane) 2] (PF6) 2, [Mn2 (µ-O) µOAc) 2 (1,4, 7-trimethyl-1,4,7-triazacyclononane) 2] (ClO4) 2, [MnIV 4 (µ-O) 6 (1,4,7-trimethyl-1,4,7

IIIIV

triazacyclononane) 2] (ClO4) 2, MnMn (µ-O) (µ-OAc) 2 (1,4,7-trimethyl-1,4,7-triazacyclononane) 2] (ClO4) 3 and mixtures thereof. See also document EP-A-549.272. Other ligands suitable for use in the present invention include 1,5,9-trimethyl-1,5,9-triazacyclododecane, 2-methyl-1,4,7-triazacyclononane, 2-methyl-1,4,7-trimethyl-1,4 , 7-triazacyclononane and mixtures thereof. See also US-A-5,194,416 which indicates mononuclear manganese (IV) complexes such as [Mn (1,4,7-trimethyl-1,4,7-triazacyclononane) (OCH3) 3] (PF6). EP-A-549271 indicates the use of the 1,4,7-trimethyl1,4,7-triazacycllononan free ligand in detergent formulations. A dinuclear manganese compound [LMnIIIMnIV (µ-O) (µ-OAc) 2] (ClO4) 2 in which L is a bis- (1,4-dimethyl-1,4,7-triazacyclononane) with an ethylene bridge , has been described in WO-96/06154.

Still, another type of bleaching catalyst, as described in US-A-5,114,606, is a water-soluble complex of manganese (II), (III) and / or (IV) with a ligand which is a polyhydroxy compound which It is not carboxylate that has at least three consecutive C-OH groups. Preferred ligands include sorbitol Iditol, dulcitol, mannitol, xylitol, arabitol, anoditol, meso-erythritol, meso-inocitol, lactose and mixtures thereof.

US-A-5,114,611 indicates another useful bleaching catalyst comprising a transition metal complex that includes Mn, Co, Fe or Cu with a non (macro) -cyclic ligand. Preferred ligands include pyridine, pyridazine, pyrimidine, pyrazine, imidazole, pyrazole and triazole rings. Optionally, said rings may be substituted with substituents such as alkyl, aryl, alkoxy, halide and nitro. Particularly preferred is the 2,2′-bispyridylamine ligand. Preferred bleaching catalysts include bispyridylmethane and bispyridyl amine complexes of Co, Cu, Mn or Fe. Highly preferred catalysts include Co (2,2'-bispyridylamine) Cl2, di (isothiocyanate) bispyridylamine-cobalt (II), trisdipyridylamine perchlorate -cobalt (II), [Co (2,2-bispyridylamine) 2O2] ClO4, bis (2,2'-bispyridylamine) copper (II) perchlorate, tris (di-2-pyridylamine) -chloride perchlorate (Iron) (II) , and their mixtures.

Various manganese and iron complexes containing (pyridin-2-ylmethyl) amine moieties as bleaching catalysts are described in EP-A-783035, EP-A-782998, EP-A-782999, WO97 / 30144, WO-00/27975, WO-00/27976, WO-00/12667 and WO-00/12668. Preferred ligands include bis (CH2COOH) (pyridin-2-ylmethyl) amine, tris (pyridin-2-ylmethyl) amine, bis (pyridin-2-ylmethylamine), N, N, N ', N'tetrakis (pyridin-2 -ylmethyl) ethylenediamine, N, N, N'N'-tetrakis (benzimidazol-2-ylmethyl) -propan-2-ol, N-methylN, N ', N'-tris (3-methyl-pyridin-2-ylmethyl) ) -ethylenediamine, N-methyl-N, N ', N'-tris (5-methyl-pyridin-2-ylmethyl) ethylenediamine, N-methyl-N, N', N'-tris (3-ethylpyridin-2- ilmethyl) -ethylenediamine, N-methyl-N, N ', N'-tris (3-methyl-pyridin-2-methylmethyl) -ethylediamine.

A series of patent applications deal with iron complexes containing the bis (pyridin2-yl) -methyl-amine moiety for the activation of peroxygen bleach and bleach bleach with atmospheric air, ie WO9534628, EP0909809, WO0060044, WO0032731, WO0012667 and WO0012668, in which iron complexes containing N, N-bis (pyridin-2-ylmethyl) 1,1-bis (pyridin-2-yl) -1-aminoethane are often the catalysts more preferred

Manganese complexes containing 1,10-phenanthroline and 2,2′-bipyridine have been described as bleaching catalysts in WO-9615136 and WO-9964554.

Manganese complexes with Schiff base ligands for bleaching stains or dyes in solution have been described in various patent applications (WO-A-00/53708, WO-A-97/44430, WO-A97 / 07191 and WO-A -97/07192).

Another preferred class of manganese complexes includes mononuclear manganese complexes containing cross-linked macrocyclic ligands. These complexes have been claimed with peroxygen compounds and without peroxygen compounds present in the formulation (WO-A-98/39405 and WO-A-00/29537). The most preferred complexes include dichloro-5,12-dimethyl-1,5,8,12 tetraazabicyclo [6.6.2] hexadecane-manganese (II) and dichloro-4,10-dimethyl-1,4,7,10 tetraazabicyclo [5.5. 2] tetradecane-manganese (II).

Another class of bispidon-containing manganese compounds as a ligand has been described as a group of bleaching catalysts in the presence and absence of peroxygen compounds (WO 0060045), of which 2,4-di (2-pyridyl) - Dimethyl 3,7-dimethyl-3,7-diazabicyclo [3.3.1] dimethyl nonan-9-one-1,5-dicarboxylate is the preferred ligand.

Other bleaching catalysts are described, for example, in EP-A-408,131 (catalysts of dinuclear cobalt Schiff base complexes), EP-A-384.503 and EP-A-306.089 (metal catalysts) -phosphyrin), US-A-4,711,748 and EP-A-224,952 (manganese absorbed on aluminosilicate catalyst) US-A-4,601,845 (aluminosilicate support with manganese and zinc or magnesium salt), US-A- 4,626,373 (manganese / ligand catalyst), US-A-4,119,557 (ferric complex catalyst, US-A-4,430,243 (chelators with manganese cations and non-catalytic metal cations) and US-A

4,728,455 (manganese gluconate catalysts).

Another class of preferred cobalt catalysts having the formula [Co (NH3) 5Cl] Cl2 has been described in EP-A-0.272.030. Still, another class of preferred catalysts of cobalt (III) [Co (NH3) 5 (carboxylate)] X2 (in which X is a non-coordinating anion), as described in US-A-580.001 and US-A- 508,198.

Inorganic polyoxomethalates as bleaching / oxidation catalysts with peroxygen and air bleach have been claimed in various patent applications, ie WO-A-97/07886, WO-A99 / 28426 and WO-A-00/39264.

The bleaching catalysts can be used in an amount up to 5%, preferably 0.0011% by weight of the composition.

Chelating agents

One or more heavy metal chelating agents may optionally be added to the washing liquid in either or both phases. Generally, chelating agents suitable for use in the present invention can be selected from the group consisting of aminocarboxylates, aminophosphonates, aromatic chelating agents with polyfunctional substitution and mixtures thereof. Although theoretical linkages are not desired, it is believed that the advantage of these materials is due in part to their exceptional ability to suppress heavy metal ions from wash solutions by forming soluble chelates; Other advantages include the prevention of inorganic films or inlays. Other chelating agents suitable for use in the present invention are the DEQUESTO commercial series and the chelants of Monsanto, DuPont, and Nalco, Inc.

Aminocarboxylates useful as optional chelating agents include ethylenediaminetetraacetates, Nhydroxyethylethylenediaminotriacetates, nitrilotriacetates, ethylenediamine tetrapropionates, triethylenetetrahexaacetates, diethylenetriamino pentaacetates and ethane dihydrides, ammonium metal salts and ammonium metal mixtures, ammonium salts and mixtures thereof.

Aminophosphonates are also suitable for use as chelating agents in the compositions of the invention when at least low levels of total phosphorus are allowed in the detergent compositions and include ethylenediaminetetrakis (methylene phosphonate). Preferably, these aminophosphonates do not contain alkyl or alkenyl groups with more than about 6 carbon atoms.

Aromatic chelating agents with polyfunctional substitution are also useful in the compositions of the present invention. See document US-A-3,812,044. Preferred compounds of this type in acid form are dihydroxydisulfobenzenes such as 1,2-dihydroxy-3,5-disulfobenzene.

A chelator for use in the present invention is ethylenediamine disuccinate ("EDDS"), especially (but not limited to) the [S, S] isomer as described in US-A-4,704,233. Trisodium salt is preferred although other forms such as magnesium salts may also be useful.

If these selective chelating agents or transition metal sequestrants are used, they will preferably comprise from about 0.001% to about 10%, more preferably from about 0.05% to about 1% by weight of the added composition.

Enzymes

In either or both phases, the washing liquid may also contain one or more enzyme (s). Suitable enzymes include proteases, amylases, cellulase, oxidases, peroxidases and lipases usable for incorporation into detergent compositions. Preferred proteolytic enzymes (protease) are catalytically active protein materials that degrade or alter the types of stain proteins when they are present in fabric stains in a hydrolysis reaction. They can be of any suitable origin, such as plant, animal, bacterial or yeast origin.

Proteolytic enzymes or proteases of various qualities and origins and having activity in various pH ranges of 4-12 are available and can be used in the present invention. Examples of suitable proteolytic enzymes are subtilisins that are obtained from particular strains of

B. Subtilis B. licheniformis, such as the commercially available subtilisins Maxatase (registered trademark) supplied by the company Gist Brocades N.V., Delft, Netherlands, and Alcalase (registered trademark), supplied by the company Novo Industri A / S, Copenhagen, Denmark.

A protease obtained from a strain of bacillus having a maximum activity in the pH range of 8-12 is particularly suitable, which is commercially available, for example, from Novo Industri A / S under the trademarks Esperase ( registered trademark) and Savinase (registered trademark). The preparation of these enzymes and other analogs is described in GB-A-1,243,785. Other commercial proteases are Kazusase (registered trademark obtained from Showa-Denko of Japan), Optimase (registered trademark of Miles Kali-Chemie, Hannover, Germany), and Superase (registered trademark that can be obtained from Pfizer of USA.).

Detergency enzymes are commonly used in granular form in amounts of about 0.1 to about 3.0% p. However, any suitable physical form of enzyme can be used.

Other optional minor ingredients

In either phase or both, the washing liquid may contain an alkali metal carbonate, preferably sodium, in order to increase detergency and ease of treatment. Sodium carbonate may be suitably present in amounts ranging from 1 to 60% p, preferably 2 to 40% p. However, compositions containing little or no sodium carbonate are also within the scope of the invention.

The powder flow can be improved by incorporating a small amount of a powder structurant, for example, a fatty acid (or fatty acid soap), a sugar, an acrylate / maleate acrylate or copolymer or sodium silicate. A preferred powder structurant is a fatty acid soap, suitably present in an amount of 1 to 5% p.

Still, other materials that may be present in the detergent compositions of the invention include sodium silicate, anti-repository agents such as cellulosic polymers, inorganic salts such as sodium sulfate; agents for regulating foaming or foaming improvers to the appropriate extent; dyes; colored particles; perfumes; foaming controllers; contrast agents and decoupling polymers. This list is not intended to be exhaustive.

Product form

The compositions to be dosed in the washing liquid to carry out the method of the present invention can be provided, for example, in the form of solid compositions such as powders or tablets or non-solid compositions such as substantially aqueous or substantially non-aqueous liquids. , gels or pastes. Optionally, the liquid compositions can be provided in water soluble sachets. Non-solid compositions, for example, liquid, may have different compositions from solid compositions and may comprise, for example, from 5% to 60%, preferably from 10% to 40% by weight of an anionic surfactant (at least part of which Of course, it will be an aromatic alkyl sulphonic surfactant, from 2.5% to 60%, preferably from 5% to 35% by weight of a non-ionic surfactant and from 2% to 99% by weight of water. Liquids may contain, for example from 0.1% to 20%, preferably from 5% to 15% by weight of soap.

Non-solid, for example, liquid compositions may also comprise (subject to any exclusions from other conditions expressed herein in the context of any aspect of the invention) one or more hydrotropes, especially when an isotropic composition is required. These hydrotropes can be selected, for example, from arylsulfonates, for example, benzene sulfonate, any of which is optionally substituted independently in the aryl ring or in the ring system with one or more C1-6 alkyl groups, by Example C1-4, benzoic acid, salicylic acid, naphthoic acid, C1-6 polyglucosides, preferably C1-4, mono-, di- and triethanolamine. When any of these compounds can exist in acid or salt form (either organic or inorganic, such as sodium), any one can be used with the condition that it is compatible with the rest of the formulation.

Preparation of the compositions.

The compositions to be added to the washing liquid can be prepared by any suitable procedure. The choice of the treatment route may be dictated in part by the stability or heat sensitivity of the surfactants involved and by the way in which they are available.

For granular products, ingredients such as enzymes, bleaching ingredients, sequestrants, polymers and perfumes that are normally added separately (for example, enzymes subsequently dosed in the form of granules, powdered perfumes) can be added after the indicated treatment steps then.

Suitable procedures include:

(one)

drum dry the main ingredients, optionally followed by granulation or subsequent dosing of additional ingredients;

(2)

towerless granulation of all ingredients in a high proportion mixer / granulator, for example, a Fukae (registered trademark) FS series mixer, preferably with at least one surfactant

in paste form so that the water in the surfactant paste can act as a binder;

(3)

towerless granulation in a combination of high speed / moderate speed granulators, thin film fast dryer / evaporator or fluidized bed granulator.

The invention will be illustrated below by means of the following non-limiting examples.

Example 1

Washing experiments were carried out at a total surfactant concentration of 0.1% p (1.0 g / l). The experiments were carried out so that the total duration of the wash cycle was kept constant for all experiments (30 minutes). The surfactant formulation applied comprised a mixture of linear alkylbenzene sulphonate (LAS) and nonionic alcohol ethoxylate (NI) at a ratio of

1: 1.

The LAS had an average carbon chain length of 11.5. The NI was Neodol 23-5 (from Shell) with a mixture of carbon chain lengths of C12 and C13 and with an average of 5 groups of ethylene oxide.

In the examples according to the invention, a 30 minute wash cycle consisted of two consecutive phases of 15 minutes each. In the first phase, the ionic strength was equivalent to 0.01% p of sodium chloride. In the second phase, the ionic strength was increased in stages by an addition of sodium chloride to bring the salt concentration to 1.0% p (or 0.17 M) or 4.0% p (or 0.68 M ). In a period of one to two minutes, the sodium chloride dissolved completely.

In respective comparative examples, the salt concentration was constant throughout the entire wash cycle (30 minutes), that is, 1.0% p and 4.0% p, respectively.

The experiments were carried out in a standard tergotometer specimen at a constant wash temperature of 27 ° C. After washing in a total period of 30 minutes and two times of rinsing with running water for 2 minutes at room temperature, the reflectance changes were measured. Two references were applied: engine oil dirt (BMD) on polyester / cotton and AS9 (a standard test casting of the CFT entity). Of these references three pieces per wash were present. Washing was carried out in experiments (embodiments) in duplicate. The reflectance changes were expressed as ΔR460 (change of reflectance at a wavelength of 460 nm). The results clearly demonstrated the best suppression of BMD with the application of the salt in the second washing phase only, compared to the use of a salt during the entire washing period.

In the AS9 wash, the decrease in yield normally observed with salt applied during the total wash phase was not found with the salt in the second wash phase.

The re-deposit was also checked in the specimens on references of white cotton and unpolluted polyester. There were no re-deposit differences as a function of the salt level in the various experiments.

Example 2

For this example, experiments were carried out on Miele Softtronic W4135 washing machines using a “30 ° C colored / white” isothermal washing program. The main wash in this program lasted approximately 55 minutes. The surfactant formulation applied comprised a mixture of linear alkylbenzene sulphonate (LAS) and nonionic alcohol (NI) ethoxylate at a ratio of 1: 1. This surfactant system is the same as that applied in Example 1. The total concentration of surfactants in the washing liquid was approximately 0.1% p (1.0 g / l).

The effect of the NaCl salt on the cleaning performance of this surfactant system was investigated by adding 0.25% p and 4.0% p of NaCl approximately in the middle of the main wash. In the comparative examples, the NaCl concentration remained constant throughout the entire main wash cycle, at 0% p, 0.25% p and 4.0% p, respectively.

The following general conditions were applied:

•

use of 10 mM tris (hydroxymethyl) methylamine buffer to obtain a pH value of 9.4-9.8;

•

no other laundry wash ingredients were applied;

•

use of demineralized water;

•

load of 2.6 kg of clean cotton in 13 l of water, so that the liquid / laundry ratio is

5. After washing in the washing machine and rinse twice with running water for 2 minutes At room temperature, reflectance changes were measured using a spectrophotome tro Minolta CM-3700d.

Various references that included engine oil dirt (BMD) on polyester / cotton and AS9 were applied. Of these references two pieces per wash were present and each wash condition was made in duplicate. The reflectance changes were expressed as ΔR460.

The results obtained clearly show the best BMD suppression when the NaCl salt was added in the middle of the main wash cycle, compared to the addition of the salt at the beginning of the main wash cycle. In addition, in the AS9 test wash, no clear decrease in cleaning performance was observed when the salt was added in the middle of the wash cycle. In addition, no re-deposit differences were found on references of white cotton and unpolluted polyester as a result of the various wash tests. These results confirm the effects of the cleaning performance of the LAS / NI 5EO surfactant system using a standard tergotometer as seen in example 1.

Claims (9)

one.

A method for washing a wash loading cloth in a washing liquid in a washing machine, said washing liquid containing a surfactant material, wherein said method comprises the step of changing the ionic strength of the washing liquid by the addition of one or more ionic ingredients thereto during a single wash cycle, characterized in that during the single wash cycle no more than 10% by weight of the washing liquid is discarded from the washing machine and because the concentration of the surfactant material in the liquid Washing is constant during the wash cycle.

2.

A method according to claim 1, wherein the washing cycle comprises at least a first phase and a second phase and wherein the ionic strength of the washing liquid is greater during the second phase than during the first phase.

3.

A method according to claim 2, wherein during at least part of said first phase, the ionic strength of the washing liquid is 0.001 to 0.06, preferably 0.02 to 0.04, more preferably 0.03 at 0.03 and most preferably from 0.005 to 0.02 M and during the second phase the ionic strength of the washing liquid is from 0.01 to 0.5, preferably from 0.02 to 0.3, more preferably from 0.03 to 0.2 and most preferably 0.04 to 0.15 M.

Four.

A method according to any one of the preceding claims, wherein either or both phases have a duration of 2 to 60 minutes, preferably 2 to 30 minutes, more preferably 3 to 20 minutes and most preferably 4 to 15 minutes.

5.

A method according to any one of the preceding claims, wherein during at least 50% of the time of variation of the ionic strength, the washing liquid has a temperature of 5 ° C to 60 ° C, more preferably 5 ° C to 38 ° C and most preferably of 10 ° C to 30 ° C.

6.

A method according to any of claims 1-5, wherein one or more ionic ingredients are added by means of a delayed release formulation dosed in the single wash cycle or before the start thereof.

7.

A method according to any of claims 1-6, wherein during the washing cycle no more than 1% by weight of the washing liquid is discarded from the washing machine.

8.

A method according to any of claims 1-7, wherein during the wash cycle the change in the concentration of the surfactant material in the wash liquid is less than 10%, preferably less than 5%.

9.

A method according to any of the preceding claims, wherein during at least part of the washing cycle the washing liquid comprises dissolved ions of sodium and / or magnesium.