Membrane-friendly pasty soap composition with enhanced defoaming properties

The present invention refers to a paste-like cleaning or detergent composition which is appropriate for the use in a washing process in which the waste water is purified by a membrane filtration unit and especially by a membrane filtration unit comprising one or more reverse osmosis steps.

The invention further relates to a method for washing textiles with a composition according to the invention and to the use of the composition as a detergent in a commercial laundry and/or in private washing machines.

Paste-like detergents or cleaning agents are known in the art, such as described, for example, in WO 98/33881 , WO 98/59025, WO 01/32819 and WO 02/46351.

The compositions mentioned in WO 98/33881 and WO 01/32819 are intended to provide alkaline paste-like compositions without synthetic anionic surfactants of the alkyl benzene sulfonate-type or non-ionic alkoxy groups containing surfactants, while at the same time providing appropriate storage stability and excellent washing performance. However, the compositions described therein lead to problems with respect to the purification of the waste water, since they cause a blocking of the filtration units used to achieve the purification.

Although WO 98/59025 tends to facilitate the purification process of the waste water accumulated during the washing cycle, especially in commercial laundries, by providing ap- propriate detergents large amounts of phosphates are used, which is critical from an environmental point of view. Additionally, it has been found that the combination of products mentioned therein is not appropriate for a waste water purification in which the filtration process comprises one or more reverse osmosis steps. However, especially the purification of the waste water by filtration comprising at least one reverse osmosis step has be- come very important in recent years, since this allows the re-use of the purified water in another washing cycle. This is of great relevance for reducing the costs of the washing process and no fresh water needs to be added to subsequent washing cycles.

The problem underlying WO 02/46351 is to provide a paste-like detergent or cleaning agent which is appropriate for use in washing processes in which the accumulated waste water is intended to become purified by a filtration process using at least one reverse osmosis step. However, the content of surfactants used therein is very low. Thus, the clean- ing performance is reduced or at least the composition is rather appropriate for soil which is easily dispersed predominantly by the alkaline properties of the liquor.

WO 2005/1 18760 A1 describes a membrane compatible pasty soap composition which can be used in a washing process in which the waste water is purified by membrane filtra- tion units. The composition does not block the membrane filtration unit and guarantees a high stream of permeate. Furthermore, the membranes can be used for a long time and after the use cycle they can be re-generated and cleaned with high efficiency.

The composition described in WO 2005/1 18760 A1 comprises a mixture of surfactants which are fatty alcohol alkoxylates and fatty alcohols. Furthermore anionic surfactants can be present. The composition further comprises an alkalinity source and one or more organic and/or inorganic builders on a non-silicate basis.

The composition described in WO 2005/1 18760, however, has the disadvantage that the foaming behavior of the composition when used in the washing process is not optimal. The usual de-foamers like fatty alcohols or paraffines or silicon oil do not avoid the foaming of the composition in a sufficient way. It is not possible either to increase the amount of de-foamer because this too does not prevent the composition from foaming. Especially if the composition is used in an industrial washing process, like in a tunnel washer, the foam is build up after the washing step when the textiles leave the tunnel and are pressed to reduce the water content in the textile. After that the textiles leave the machine on a conveyer belt equipped with sensors which can recognize foam. If foam is detected by the sensor, the conveyer belts stop and the whole process in the tunnel washer is interrupted. As the tunnel washing is a continuous process, this means that the whole process stops and has to be started again by manual operation.

A further disadvantage of the defoamers which are used in the state of the art is that they are not membrane-compatible and tend to block the membranes of the membrane filtration unit of the industrial washing machine.

Therefore it is the technical object of the present invention to provide a paste-like cleaning or detergent composition which is membrane compatible and shows an optimal foaming behavior when used in industrial washing processes.

This technical object is solved by the composition comprising

a paste-like cleaning or detergent composition comprising a) a surfactant component comprising a compound of the general formula R ¹ -COOM (I), wherein R ¹ represents a linear or branched alkyl- or alkenyl residue with 8 to 22 carbon atoms and M represents an alkali metal ion; a fatty alcohol alkoxylate and/or an oxo alcohol alkoxylate with 8 to 22 carbon atoms and an average degree of alkoxylation of at least 5; and optionally an anionic surfactant; b) a compound of the general formula R ² -O-R ³ (II), wherein R ² represents a linear or branched alkyl or alkenyl residue with 8 to

22 carbon atoms and R ³ represents hydrogen or a linear or branched alkyl residue with 1 to 8 carbon atoms; c) water and/or a compound of the general formula X-CH ₂ -(CHY) _n -CH ₂ -Z (III), wherein n is an integer of from 0 to 2 and X, Y and Z independently symbol- ize hydrogen or a hydroxyl group provided that at least 2 hydroxyl groups are present; d) one or more alkalinity sources, and e) one or more organic and/or anorganic builders on a non-silicate basis; f) a defoamer comprising cross linked or partly cross linked polysiloxane hav- ing a three dimensional structure.

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It was surprisingly found that if a defoamer is used comprising a cross-linked or partly cross-linked polysiloxane having a three-dimensional structure, the membranes are not blocked and in addition thereto a good foaming behavior of the composition is achieved.

The use of silicon oils as foaming-regulators in washing an cleaning compositions is, in principle known. Typical foam-regulators which are used in detergents can be, for example, mixtures of silicon oil and silica wherein the silica particles can preferably be silan- ised. The silicon oil which is used normally is a linear polysiloxane compound. Other foam inhibitors which are also used in the state of the art are paraffins, hydrocarbons, saturated fatty acids or soaps, alkali metal salts or phosphoric acid mono esters or dialkyl esters.

A further group of defoamers are organo modified polyether siloxanes which have organo functional groups in their side chains. Such a compound is, for example, Y-14765 avail- able from GE silicones.

It was surprisingly found that these kinds of organo modified silicon oils have the disadvantage that they are not membrane-compatible and block the membrane.

In contrast thereto it was found that cross-linked or partly cross-linked polysiloxanes having a three-dimensional structure are fully membrane-compatible and do not block the membrane. In addition thereto they show very good foam regulation properties. Such three-dimensional polysiloxanes are normally used in form of an emulsion which contains the cross-linked siloxane droplets which are preferably modified by organo-functional groups.

Such partly cross-linked polysiloxanes having a three-dimensional structure are, for example, available from Mϋnzing Chemie under the trade name Foam Ban ^R .

The composition according to the invention has the further advantage that it does preferably not contain any compounds which are not membrane-compatible, like, for example, grain inhibitors on a cellulose basis, and silicates. Furthermore it is preferred that the composition according to the invention does not contain other polysiloxane compounds or silicon oils except cross-linked or partly cross-linked polysiloxanes having a three- dimensional structure.

In a preferred embodiment the polysiloxane compound is used in form of a dispersion or an emulsion.

In a further preferred embodiment the polysiloxane has organo functional groups. These organo functional groups can be hydrocarbon groups with 1 to 20 carbon atoms. Preferably these organo functional groups are selected from the groups consisting of C ₁ -C ₂ 0 alkyl groups, CrC ₂ O alkenyl groups, CrC ₂ O alkoxy groups, C ₄ -C ₂ O aryl or aralkyl groups. Furthermore the hydrocarbon groups can be substituted.

Examples of the hydrocarbon groups are methyl, ethyl, vinyl, propyl, isopropyl, n-butyl, n- pentyl, cyclopentyl, n-hexyl, neohexyl, n-heptyl, norbornyl, 2-ethylhexyl, n-octyl, isooctyl, dodecyl, tetradecyl, hexadecyl and octadecyl groups. The substituents of these groups can be, for example, trifluorpropyl group, cyanoethyl group, glycidyloxypropyl group, polyalkylene glycol propyl group, amino propyl group or aminoethylaminopropyl groups. Also possible are unsaturated groups, like, for example vinyl, methacryloyloxypropyl or allyl groups or aromatic groups such as phenyl, 2-phenyl-ethyl or 2-phenyl-propyl groups.

In a further embodiment the defoaming composition can further comprise filler particles. The filler particles are selected from the group consisting of silica, titanium dioxide, zirco- nium dioxide, Al ₂ θ3 or mixtures thereof.

In a preferred embodiment the defoamer is used in an amount of from 0.01 to 10 wt.-% based on the whole composition. Preferably the defoamer is used in an amount of 0.05 to 7, more preferred 0.1 to 5 and most preferred 0.1 to 2 wt.-% based on the whole composi- tion.

The composition according to the invention is preferably essentially free of other polysiloxane oils and polysiloxane resins which do not have a three-dimensional structure and are not membrane-compatible. The composition according to the invention is most pre- ferred essentially free of linear polydimethyl siloxanes (silicon oils).

The expression "essentially free" means that the composition includes the compound in an amount which is lower than 0.001 wt.-%, preferably lower than 0.0001 wt.-%, and most preferred 0 wt-% based on the whole composition. Most preferred the expression "essen- tially free" means that the related compound is not at all present in the composition.

In the defoamer composition according to the invention cross-linked or partly cross-linked polysiloxanes are used having a three-dimensional structure.

These polysiloxanes are cross-linked or partly cross-linked which means that they contain groups of chain- or ring-forming molecules which are connected by tri- or tetra-functional siloxane units to a three-dimensional network. In contrast thereto the expression "cross- linked or partly cross-linked polysiloxane having a three-dimensional structure does not comprise linear polysiloxanes like polydimethylsiloxane, branched polysiloxanes which only have a two-dimensional structure and cyclic polysiloxanes which also only have a two-dimensional structure.

Furthermore, the cross-linked polysiloxanes having a three-dimensional structure according to the invention are preferably fluids and therefore are delimited from silicone resins which are heavily cross-linked polymer networks and are solid at room temperature.

Therefore, it is preferred that the cross-linked or partly cross-linked polysiloxanes having a three-dimensional structure which are used in the defoamer, are fluids at room temperature (20 ⁰ C).

Figure 1 describes a comparison of the stream of permeate through the membrane between the composition according to the invention containing three- dimensional polysiloxanes compared with a composition according to the state of the art using a usual silicone oil defoamer.

Figure 2 shows the stream of permeate for a reverse osmosis membrane which was used with a composition according to the invention and a composition according to the state of the art for 3.000 hours. Figure 2 shows the results of the measurement after cleaning of the membrane.

The paste-like cleaning or detergent composition according to the invention comprises further components which are described in the following.

In the salts of the carboxylic acids corresponding to formula (I) R ¹ may be linear or branched, for example with a methyl residue in 2-position, wherein linear residues are

preferred, like they generally occur in fatty acids. Optionally, residue R ¹ contains one or more double bonds. Preferably, R ¹ in formula (I) has 8 to 22 carbon atoms, more preferred 12 to 20 and most preferred 15 to 19 carbon atoms. Such compounds may be exemplified by alkali metal salts of octanoic acid, pelargonic acid, decanoic acid, lauric acid, lauroleic acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, petroselinic acid, petroselaidic acid, oleic acid, linoleic acid, linolaidic acid, linolenis acid, eleostearic acid, arachic acid, gadoleic acid, arachidonic acid, behenic acid, erucic acid, brassidic acid, clupanodonic acid and mixtures thereof. Sodium and potassium as well as mixtures thereof represent preferred alkali metals. When preparing the inventive composi- tions it is as well possible to use the free carboxylic acids and convert them into to the corresponding alkali metal salt by addition of alkalinity sources or other alkalinic salts, especially alkali hydroxides or alkali carbonates, which are present anyway.

Preferably, the composition contains the compound of formula (I) in an amount of from 5 to 25 wt.-%, preferably 8 to 20 wt.-%, based on the whole composition.

The fatty alcohol alkoxylate and/or an oxo alcohol alkoxylate contains 8 to 22 carbon atoms and an average degree of alkoxylation of at least 5, preferably at least 7. In a preferred embodiment the alkoxylate corresponds to the general formula R-(EO) _x -(PO) _y in which R denotes the fatty alcohol and/or oxo alcohol moiety with 8 to 22 carbon atoms, EO represents ethyleneoxide residues and PO represents propyleneoxide residues and x and y denote integers, wherein the sum of x and y is at least 5 and one of x or y may be 0.

The fatty alcohols appropriate in the present invention can be exemplified by the alcohols obtained from the fatty acids as mentioned above. Oxo alcohols generally represent a mixture of the linear alcohol and the alcohol which is branched with methyl in 2-position. Preferably the alcohol has 12 to 15, more preferred 13 to 14 carbon atoms. Technical mixtures may additionally contain proportions with 11 to 15 carbon atoms.

In a preferred embodiment in case that y is 0 x is at least 7. Are both x and y unlike 0, preferably x is from 4 to 8 and y is from 2 to 8, especially from 3 to 4.

The fatty alcohol alkoxylate and/or oxo alcohol alkoxylate may be present in an amount of from 0,5 to 15 wt.-%, preferably of from 1 ,5 to 8 wt.-%, based on the whole composition.

The composition according to the invention optionally contains an anionic surfactant in an amount of from 0 to 15 wt.-%, preferably of from 1 ,5 to 8 wt.-%, which may be selected from the compounds comprising C ₈ -Ci ₈ -alkyl sulfates, C ₈ -Ci ₈ -alkyl ether sulfates, C ₈ -Ci ₈ - alkylsulfonates, C ₈ -Ci8-a-olefinsulfonates, sulfonated C ₈ -Ci ₈ -fatty acids, C ₈ -Ci ₈ - alkylbenzenesulfonat.es, sulfosuccinic mono- and di-CrCi ₂ -alkyl esters, C ₈ -Ci ₈ -alkyl poly- glycol ether carboxylates, C ₈ -Ci ₈ — N-acyl taurides, C ₈ -Ci ₈ — N-sarcosinates, C ₈ -Ci ₈ -alkyl isethionates and mixtures thereof.

Moreover, the composition optionally contains at least one alkyl polyglucoside having from 8 to 14 carbon atoms in the alkyl group and from 1 to 5 glucose moieties. The amount of the alkyl polyglucosid should in the range of from 1 to 6 wt.-%, preferably from 1 to 3 wt- %

The alcohols or ethers corresponding to the general formula (II), respectively, contribute to the low-temperature resistance of the inventive composition and additionally may improve its washing performance. The definition of R ¹ as mentioned above applies for R ² as well. R ³ preferably denotes hydrogen or a methyl, ethyl, propyl or butyl group, wherein hydrogen or the methyl group are most preferred. In an especially advantageous embodiment the composition contains the compound of formula (II) in an amount of from 1 to 20 wt.-%, preferably of from 3 to 15 wt.-%.

The polyols represented by the general formula (III) are exemplified by ethylene glycol, 1 ,2-propylene glycol, 1 ,3-propylene glycol, glycerine, 1 ,4-butylene glycol and mixtures thereof, wherein 1 ,2-propylene glycol is most preferred. The inventive composition con- tains water and/or the compound of formula (III) in an amount of from 5 to 70 wt.-%, preferably from 20 to 45 wt.-%, wherein the water content preferably ranges from 15 to 50 wt.-%, more preferred from 25 to 38 wt.-%, and the content of the compound of formula (III) preferably ranges from 3 to 20 wt.-%, more preferred from 5 to 15 wt.-%, based on the whole composition. In case that water as well as polyol corresponding to formula (III) are present their weight ratio preferably is in the range of from 1 :1 to 7:1 , and particularly in the range of from 2:1 to 4,5:1. In a further preferred embodiment the weight ratio of alcohol or ether of the general formula (II), respectively, to polyol lies in the range of from 1 :1 to 1 :15, preferably 1 :1 , 5 to 1 :10.

Generally, the solid phase of the inventive composition is formed from the alkalinity source and organic and/or anorganic builders. Optionally further particulate auxiliaries may be

incorporated. The solid phase should be dispersed in the liquid phase as homogeneous as possible. If the particulates are not fine enough to appropriately form a paste they may be grinded one or more times by conventional methods as known in the art.

The inventive composition preferably contains one or more alkalinity sources in a total amount of from 10 to 30 wt,-%, preferably of from 15 to 25 wt.-%, based on the whole concentrate. Generally they belong to the solid phase of the paste. Under using conditions the alkalinity source(s) provide(s) a washing liquor with a pH value in the range of from 8 to 13, preferably of from 10 to 12 (measured in form of a solution of 1 wt.-% of the compo- sition in ion exchanged water). Alkalihydroxide, especially sodium hydroxide which advantageously may be used in form of a 50 wt.-% aqueous solution, represents a preferred alkalinity source. Moreover, alkali carbonate and alkali hydrogen carbonate, like for example sodium carbonate, represent appropriate alkalinity sources.

The one or more anorganic builders on a non-silicate basis and/or organic builders may be present in the composition in an amount of from 8 to 45 wt.-%, preferably 12 to 30 wt- %, based on the whole composition. The most appropriate anorganic builder which is on a non-silicate basis is represented by sodium carbonate which as well functions as alkalinity source. Sodium hydrogencarbonate or borate compounds, especially alkali borates, more preferred borax, may as well be used.

Organic builders may be exemplified by monomer polycarboxylic acids or hydroxycarbox- ylic acids like citric acid or gluconic acid as well as amino polycarboxylic acids and poly phosphonic acids. Examples for amino carboxylic acids are nitrilotriacetic acid, ethylene diamine tetraacetic acid, diethylene triamine pentaacetic acid and higher homologues thereof, wherein N,N-bis(carboxymethyl) aspartic acid is preferred. Suitable polyphso- phonic acids may be represented by 1 -hydroxyethane-1 ,1 -diphosphonic acd, ami- notri(methylene phosphonic acid), ethylene diamine tetra(methylenephosphonic acid) and higher homologues thereof, like for example diethylene tetraamine tetra(methylene phos- phonic acid). The above mentioned acids are generally applied in form of their alkali metal salts, especially their sodium or potassium salts.

Moreover, homopolymer and/or copolymer carboxylic acids or alkali salts thereof, respectively, and particularly their sodium or potassium salts, also represent suitable organic builders. In a preferred embodiment polymer carboxylates or polymer carboxylic acids, respectively, having a relative molecular weight of at least 350, in form of their water-

soluble salts, especially in form of their sodium or potassium salts, are applied, like oxidized polysaccharides according to International patent application WO 93/08251 , poly- acrylates, polymethacrylates, polymaleates and, in particular, copolymers of acrylic acid with maleic acid or maleic anhydride, preferably those containing 50 to 70% acrylic acid and 50 to 10% maleic acid which are characterized, for example, in European patent EP 022 551. The relative molecular weight of the homopolymers is generally between 1 ,000 and 100,000 while the relative molecular weight of the copolymers is between 2,000 and 200,000, and preferably between 50,000 and 120,000, based on free acid. A particularly preferred acrylic acid/maleic acid copolymer has a relative molecular weight of from 50,000 to 100,000, more preferred 60,000 to 80,000.

Suitable but less preferred compounds of this class are copolymers of acrylic acid or methacrylic acid with vinyl ethers, such as vinyl methyl ethers, vinyl esters, ethylene, propylene and styrene, in which the acid makes up at least 50% by weight. Other suitable water-soluble organic builders in form of polymer carboxylates or carboxylic acids are ter- polymers which contain two unsaturated acids and/or salts thereof as monomers and vinyl alcohol and/or a vinyl alcohol derivative or a carbohydrate as the third monomer. The first acidic monomer or its salt is derived from a monoethylenically unsaturated C3_8 carboxylic acid and preferably from a C _3-4 monocarboxylic acid, more especially (meth)acrylic acid. The second acidic monomer or its salt may be a derivative of C _4- S dicarboxylic acid, maleic acid being particularly preferred. The third monomer unit in this case will be formed from a vinyl alcohol and/or preferably an esterified vinyl alcohol. Especially preferred are vinyl alcohol derivatives which form an ester of short chain carboxylic acids, like d-C ₄ carboxylic acids, with vinyl alcohol. Preferred terpolymers contain 60 to 95 wt-%, particularly 70 to 90 wt.-% (meth)acrylic acid or (meth)acrylate, respectively, more particular acrylic acid or acrylate, respectively, and maleic acid or maleinate and 5 to 40 wt.-%, preferably 10 to 30 wt. -% vinyl alcohol and/or vinyl acetate. Especially preferred are terpolymers with a weight ration of (meth)acrylic acid and maleic acid or maleinate of between 1 :1 and 4:1 , preferably between 2:1 and 3:1 and especially 2:1 and 2,5:1 , with the amounts as well as the weight ratios being based on the acid.

The second monomer or its salt may also be a derivative of an allyl sulfonic acid substituted in the 2-position by an alkyl group, preferably a CrC ₄ alkyl group, or an aryl group which is preferably derived from benzene or a benzene derivative. Preferred terpolymers contain 40 to 60 wt.-%, in particular 45 to 55 wt.-% (meth)acrylic acid or (meth)acrylate, more preferred acrylic acid or acrylate, 10 to 30 wt.-%, particularly 15 to 25 wt.-% methal-

IyI sulfonic acid or methallyl sulfonate and as third monomer 15 to 40 wt.-%, preferably 20 to 40 wt. -% of a carbohydrate. Said carbohydrate, for example, may be a mono, di, oligo or polysaccharide, with mono, di or oligosaccharide being preferred. Saccharose is most preferred.

By applying the third monomer breaking points are implemented into the polymer which probably result in the good biodegradability properties of said polymers. Polymers which are completely or at least in part neutralized, particularly to more than 50% based on the carboxylic groups which are present, are especially preferred.

Most preferred polymeric polycarboxylates may be produced by the method described in German patent DE 42 21 381 and German patent application DE 43 00 772. The polya- cetal carboxylic acids described, for example, in U.S. Pat. Nos. 4,144,226 and 4,146,495, which are obtained by polymerization of esters of glycolic acid, introduction of stable ter- minal groups and saponification to the sodium or potassium salts are also suitable, as are polymeric acids obtained by polymerziation of acrolein and Cannizzaro disproportionation of the polymer with strong alkalis. They are essentially made of acrylic acid units and vinyl alcohol units or acrolein units.

Preferably the composition of the present invention is essentially free from graying inhibitors on a cellulose base, silicates and phosphates. In this context essentially free means that the content based on the whole composition is below 1 wt.-%, preferably below 0,5 wt. -% and most preferred the composition is totally free from said compounds.

Graying inhibitors on a cellulose base which are not contained in the inventive composition can be exemplified by cellulose ethers, like carboxymethyl cellulose, methyl cellulose, hydroxyalkyl cellulose, and cellulose containing different ethers, like methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose and methyl carboxymethyl cellulose.

Crystalline alkali silicates, as well as alkali alumosilicates, especially zeolites, for example, belong to the silicates which are absent in the present composition.

The present composition may comprise further auxiliaries and additives which are com- monly known to be used in detergent and cleaning compositions, like enzymes, soil-

release components, optical brighteners, foam regulating agents, dye inhibitors or intensi- fiers and/or perfumes.

From a practical point of view, it is preferred that the composition is prepared by first pre- paring a homogeneous pre-mixture containing the surfactant component a) and the solu- tizer system comprising the alcohols or ethers according to general formula (II) and water and/or polyols of the general formula (III) and then incorporating the solids and further additives therein. If it seems necessary to improve the fineness of the particulates to form stable pastes one or more grinding steps may be applied.

The inventive composition preferably exhibits at 25°C a viscosity of from 100,000 mPas to 500,000 mPas, more preferred 300,000 to 500,000 mPas at 5 revolutions per minute and a viscosity of from 15 000 mPas to 80 000 mPas, more preferred 30,000 to 60,000 mPas at 50 revolutions per minute, each measured using a Brookfield rotational viscometer (spindle no. 7) under otherwise identical conditions.

Moreover, the concentrate exhibits such a structural viscosity that it does not flow under the influence of gravity. However, on shear the viscosity tremendously decreases which enables the concentrate to flow under the influence of gravity. The dosing of such a thixotropic composition is then preferably performed by shearing the concentrate to reduce viscosity at first and afterwards dosing and transmitting the free-flow concentrate using for example a feed pump. The above mentioned viscosity values refer to reading after a detection time of 3 minutes to take the time dependency of the thixotropic effect into account. The decrease of viscosity on shear is to a great extent reversible, i. e. after having stopped the shear the concentrate will return to its original physical condition without separation.

The present invention also refers to a method for washing textiles using the above mentioned composition, especially in commercial laundries. However, such compositions may as well be used in private washing machines, as a cleaning agent in general and/or as a warewashing agent, although the application in commercial laundries is especially advantageous.

As mentioned above, the inventive composition is membrane friendly, which means that it neither causes blocking of the membrane or other damages when it is contained in the waste water which is accumulated during the whole washing process or parts thereof and

which is supposed to be purified using membrane filtration units. It is even possible that the filtration process comprises one or more reverse osmosis steps. This means, the permeation of the waste water to be purified generally remains stable.

In addition, the membranes can be used in several use cycles because they can be cleaned after one use cycle. After cleaning they still show a stream of permeate which is similar to that of a new membrane. This means that the composition according to the invention does not block the membrane and no components of the composition adhere to the membrane. The membranes which are used with the composition according to the invention can be sufficiently cleaned and re-used in another washing cycle.

The use of the membranes has the advantage that the purified water which is obtained from the waste water may be re-used in another washing cycle. This results in a decrease of the amount of fresh water required to be added to the washing cycle and accordingly in a reduction of costs and in saving resources.

Furthermore, the composition according to the invention shows a better foam behavior than membrane-compatible compositions according to the state of the art. If the composition according to the invention is used in the washing process, less forming occurs so that a continuous process without any interruptions is achieved.

Moreover, it has been found that the biodegradability of the inventive composition is not deteriorated but in most cases even improved. This represents a very advantageous property taking into account the ecological demands on detergents and cleaning composi- tions nowadays.

The inventive composition will be further described in the following examples which are only meant to exemplify the present invention without restricting its scope.

Examples

Example 1 to 5

In the following the amounts mentioned refer to wt.-% based on the whole composition unless otherwise indicated.

In the following table 1 , examples 1 to 5 are examples according to the invention with a defoamer comprising cross-linked or partly cross-linked polysiloxane having a three-dimensional structure.

Furthermore, table 1 contains two comparative examples, namely comparative example 1 which is without any polysiloxane defoamer and comparative example 2 containing a silicone oil as defoamer.

Example 6

Foam test of composition C1 and composition Ex.2

In this example the foaming behavior of the composition according to the invention is compared with compositions according to the test of the art containing no de- foamer and containing silicone oil as defoamer.

The following table 2 shows the result of the foam test.

It can be seen that the composition according to the invention in example 2 shows a good foaming behavior compared to the composition in comparative example 1 without an anti-foaming agent. Furthermore, the foaming characteristic of example 2 is similar to that of comparative example 2.

However, the composition according to the comparative example blocks the membrane which is shown in figures 1 and 2.

Figure 1 describes a comparison between the composition according to the invention containing three-dimensional polysiloxanes compared with a composition according to the state of the art using a usual silicone oil defoamer. It can be seen from figure 1 that the stream of the permeate through the reversed osmosis mem- brane is for the composition according to the invention between 100 and 110 % wherein the stream of the permeate with a composition according to the state of the art decreases from 100 % to 75 %.

The comparative examples were carried out by measuring the permeate stream every twenty minutes. In order to simulate the long use cycle of the reversed osmosis membrane, which is about 3.000 machine hours, additional composition was added every twenty minutes. At the beginning, the concentration of the composition was 0.05 wt. -% and at the end 0.6 wt.-%. By this proceeding, the stress on the membrane is simulated, which occurs during the long use period before cleaning of the membrane.

From figure 1 can be seen that the compound according to the invention is fully membrane-compatible and does not block the membrane compared to the composition according to the state of the art which blocks the membrane. If the mem- brane is blocked, it means that the membrane has to be cleaned during which the washing process is interrupted.

Figure 2 shows the stream of permeate for a reverse osmosis membrane which was used with a composition according to the invention and a composition accord- ing to the state of the art for 3.000 hours. After that, the membrane was cleaned and again the stream of permeate was measured. Figure 2 shows the results of the measurement after cleaning of the membrane. It can be seen that the composition according to the invention shows after cleaning only a stream of permeate of 60 % while the membrane which was used before with the composition according to the invention shows a stream of permeate of more than 90 %. This means that the membranes which are used with a composition according to the invention can be successfully cleaned up to a stream of permeate of more than 90 % of the original stream which can be achieved for a new membrane (100 %).