BRPI0510349B1 - CLEANING METHOD - Google Patents

Description

FIELD OF THE INVENTION Field of the Invention The present invention relates to the field of tissue cleaning methods. The invention particularly relates to a method of treating water to obtain water which is suitable. for use with low environmental impact detergent products.

BACKGROUND OF THE INVENTION In recent years, it has been known about the impact of human activities on the environment and the negative consequences this may have. Means of reducing, reusing and recycling sources are becoming more important. Fabric cleaning is one of many household activities with a significant environmental impact. This is partly caused by the use of conventional detergent products, which tend to be retatively complex compositions with a variety of ingredients. Over the years some ingredients have been banned by legislation in certain countries because of their adverse environmental effects. Examples include certain nonionic surfactants and reinforcers such as phosphates. The use of phosphates in detergents has been linked to increased phosphate levels in surface waters. The resulting eutrophication is believed to cause increased algae growth. Increased algae growth in standing surface water leads to decreased oxygen in lower water layers, which in turn causes overall reduction in total water quality.

Although some ingredients in conventional laundry detergent products may have a limited environmental effect, the energy involved in their production influences the environmental impact during their life cycle negatively. Life cycle analysis typically estimates the environmental impact of a product during different phases such as production of raw material, production of the product itself, distribution to the end user, use of the product by, for example, the consumer and disposal after use.

Environmental impact may include factors such as eutrophication, greenhouse effect, acidification and photochemical oxidant formation. For laundry detergent products, extra ingredients necessarily add cost, volume and weight to the product, which in turn requires more packaging material and shipping costs. Extra ingredients usually require a more complex production process. However, reducing the number and / or quantity of ingredients is difficult without reducing cleaning effectiveness.

One of the bulkier ingredients of common laundry detergents are so-called reinforcers such as zeolites, phosphates and carbonates. Reinforcers are currently added to laundry detergent formulations for their ability to sequester hardness ions such as Ca2 + and Mg2 +. Reduction of hardness ions is required to prevent the deposition of calcium soaps in the dirt, to prevent precipitation of anionic surfactants, to maximize colloidal stability and to reduce substrate-dirt-calcium interaction and dirt-dirt interaction. and then to improve dirt removal. Apart from their positive effects, common reinforcers can also have negative effects on laundry cleaning processes. For example, reinforcers often generate wash-insoluble materials or such as or by the formation of precipitates. For example, zeolites are insoluble and may cause tissue fouling and heating of washing machine elements and calcium reinforcer precipitates may result in increased redeposition.

From the above it will be clear that on the one hand the removal of hardness ions is required to ensure good cleaning performance, while on the other hand the presence of reinforcements in laundry detergents contributes significantly to their environmental impact. In addition, reinforcers can also have negative effects on the performance of a laundry cleaning process.

An attractive solution to the above problems may be the removal of hardness ions from the wash water before they come into contact with the detergent solution fabrics. Ion exchange could be a possible technique for removing hardness ions from tap water, which could allow for the removal of detergent reinforcers, thereby reducing their environmental impact. In a recent Hitachi patent (US-A 6,557,382), ion exchange-based water softening has been described. Ion exchange removes hardness ions (Ca2 + and Mg2 +) from water by exchanging them with so-called substitution ions, typically Na + or H +, which are stored in ion exchange resins. The resin is depleted when most of the replacement ions have been replaced by hardness ions.

However, in order to augment the resin, also called resin regeneration, a strong solution of the recharge ions is generally applied to the resin. This changes the ions that have been removed from the water and regenerates the resin. For this purpose, usually a concentrated salt solution or strong acid or base solution is used which is undesirable for household laundry application for reasons of negative environmental impact, high cost and lack of user convenience and comfort. It would therefore be desirable to regenerate ion exchange resins by a non-polluting method that is especially suitable for the application of cleaning processes for household laundry.

Other bulky ingredients of common main laundry detergents are so-called buffers such as, for example, carbonate, disilicate or meta-silicate. These buffer components are added to detergent formulations to achieve and maintain the desired pH of the wash solution. The pH of a wash solution is usually kept above 10 to increase removal of particulate dirt and grease. Therefore, on the one hand the establishment of a high pH is required to ensure a good cleaning performance while on the other hand the presence of laundry detergent buffers contributes to its environmental impact as pointed out above.

Accordingly, one object of the present invention is to disclose an economical method having low environmental impact to remove hardness ions from tap water and to modify the pH. Another object of the present invention is to disclose a method for removing hardness ions from tap water and for modifying the pH of said water in a manner that is convenient and comfortable for consumers. Yet another object of the invention is to disclose a suitable method for treating tap water such that water is obtained which is suitable for use with a low environmental impact detergent (LEIP) as defined herein in tissue cleaning method. Still another object of the invention is to disclose a cleaning method whereby water obtained from such a water treatment method can be suitably used with a LEIP in household cleaning apparatus such as a fabric washer.

A known method for water treatment is the so-called electrodeionization (EDI) method, which combines ion exchange and electrodialysis. The resulting hybrid process does not require regenerating chemicals. An EDI module may, for example, consist of a repeated combination of a dilution chamber containing cationic and / or anionic exchange resins confined within the cationic and anionic exchange membranes, a concentration chamber and finally electrolyte chambers. Water can flow through the various chambers in separate cycles. Cations such as Ca + 2 and Mg + 2 are attracted to the cathode, and anions are attracted to the anode, with the resin acting as a conduction medium. The ions are transferred to the concentration chamber by applying DC current resulting in a voltage of typically in a range between 10 and 300 V. Thus soft water is obtained. The current has the effect of separating water molecules into H * ions and OH 'ions. H + ions and OH 'ions keep the resin in a regenerated state. During the ion exchange process ions in water, for example tap water, are replaced by ion replacement resin replacement ions. When ion exchange resins are used which are mainly in the form H + or OH 'ion exchange can also be used to modify the pH of the tap water stream by appropriate selection and order of ion exchange resins. One or more of said confinement membranes may be in the form of so-called bipolar membranes which consist of a cationic or anionic exchange membrane layer pressed together into a single sheet. The desired function of such membranes is a reaction at the bipolar membrane junction. Here water is separated into H + and OH ions by a so-called 'disproportion' reaction. Water separation in a bipolar membrane can be explained by looking more closely at the interface between the cationic and anion exchange membrane. Here the negative groups of the cation exchange polymer closely approximate the positive groups of the anion exchange polymer to form a salt. Counterions, for example, H + and OH 'move apart under the influence of the applied electric field rather than recombining with water. Being in equilibrium, salt will react with water and resume the resins to their initial states. Definition of the Invention Surprisingly, a cleaning method for low environmental impact detergent products has been found which allows one or more of the above objects to be achieved.

Accordingly, the present invention provides a cleaning method comprising the steps of: (i) contacting feed water consecutively appropriate combination of ion exchange resin material and anion exchange resin material to produce wash water (WAW) having a water hardness of less than 5 ° FH and a pH value that is greater than a pH unit of 0.5 different from that of the feedwater, whereby resins are regenerated using a field electric; (ii) mixing said WAW with a low environmental impact detergent (LEIP) which is substantially free of reinforcer and comprises at least 10 wt%, preferably at least 25 wt%, more preferably at least 40 wt%, surfactant to obtain the wash liquor; and (iii) treating substrates to be cleaned with said wash liquor.

For the purpose of the present invention, the feed water is defined as water having a conductivity of more than 50 micro Siemens cm -1, preferably more than 100 micro Siemens cm -1 and more preferably more than 200 micro Siemens cm -1. "1. For practical reasons, the feed water is desirably tap water from the main pipeline having a hardness of water having at least 7 ° FH.

Preferably, step (iii) of the cleaning method of the invention is performed in a dishwasher or fabric. Accordingly, it is desirable for the improved wash water to have a pH above 8.5, more preferably above 9.5.

The cleaning method of the invention is particularly suitable for home use and the WAW obtained from said method is suitable for use in a home cleaning apparatus.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from reading the following detailed description and appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be used in any other aspect of the invention. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention by those examples themselves. Other than in the experimental examples, or where otherwise indicated, all numbers expressing amounts of ingredients or reaction conditions used herein are to be construed as modified in all cases by the term "about". Similarly, all percentages are weight / weight percentages of the low environmental impact detergent product composition unless otherwise indicated. Numeric ranges expressed in the form of “x to y” are understood to include x and y. When for a specific feature several preferred bands are described in the "de xay" format, it is to be understood that all bands combining the different points are also contemplated. Where the term "comprising" is used in the application or claims, it is not intended to exclude any terms, steps, or characteristics not specifically shown. All measurements are in SI units unless otherwise specified. For example, all temperatures are in degrees Celsius (DC) unless otherwise specified. Water hardness is expressed in French degrees (eFH). All relevant parts of the cited documents are incorporated herein by reference.

Detailed Description Of The Invention The improved wash water WAW that is obtained as a consequence of step (i) of the method of the invention is particularly suitable for use in a household cleaning apparatus. The household appliance may be any cleaning-related device such as a washing machine, in particular a dishwasher or fabric. As is known, certain household appliances, particularly dishwashers, are provided with a system, also known as a water softener or softener, to reduce water hardness. In particular, such a system is provided for reducing the calcium and magnesium contents of water used for washing purposes, which may inhibit the action of detergents and produce scale deposits; In fact, limestone deposits are due to an excessive amount of calcium ions (Ga + Z) and magnesium ions (Mg2 *) contained in water supplied by the sea. Ion exchangers to remove hardness ions (Ca * 2 and Mg * 2) from water are applied in some dishwasher chains, typically using Na * as so-called replacement ions. Water flows over the resin and the hardness ions in the water are exchanged with the replacement ions in the resin. The resin is depleted when most of the replacement ions have been replaced by hardness ions. In order to augment the resin, also called resin regeneration, a strong solution of the recharge ions is generally applied to the resin. By virtue of the above discussion such a regeneration method is undesirable.

Accordingly, the present invention has among others the object of providing a method of treatment of the wash water in which the feed water is consecutively contacted with an appropriate combination of cation exchange resins and anion exchange resins in order to produce enhanced wash water (WAW) having a pH that is more than a pH unit of 0.5 other than feed water and a water hardness of less than 5 ° FH, and which resins are regenerated using a field electric. Resin regeneration is preferably performed using electrodeionization (EDI).

In order to be effective for washing processes, WAW has to fulfill a number of requirements. First of all, the hardness of the water is less than 5 ° FH, preferably less than 2 ° FH and more preferably less than 1 ° FH. Reduction of water hardness is required to prevent the deposition of calcium soaps in the dirt, to prevent precipitation of anionic surfactants, to maximize colloidal stability and to reduce substrate-dirt-calcium interaction and dirt-dirt interaction and thus to improve dirt removal. Finally, WAW pH is an important parameter. As explained above, the pH of a conventional washing solution is usually maintained above 10 ° C to improve particulate and grease removal. Thus, it is preferred that the WAW pH for the average wash is greater than 8.5, more preferably greater than 9.5. However, for special cleaning purposes or other purposes it may be advantageous to be able to perform a wash at an acidic pH of, for example, 5. In the latter case, it is preferred that the WAW pH value be greater than 3, more preferably. greater than 4, and even more preferably greater than 5, but less than 7.5.

It is preferred that step (i) of the cleaning method of the invention be capable of producing both acidic and basic WAW. As a consequence, the WAW has a pH value that is greater than a pH unit of 0.5, preferably greater than a pH unit of 1.0, more preferably greater than a pH unit of 1.5 different from feed water. .

WAW properties can be adjusted using appropriate combinations of ion exchange resins. Ion exchange resins may be a salt, acid or base in a solid form that is water insoluble but hydrated. Exchange reactions occur in water, retained by the ion exchanger. An ion exchange resin consists of a polymeric matrix and functional groups that interact with ions. Examples of well known polymeric matrices are polystyrene resins, formaldehyde phenol resins, polyalkylamine resins and polyacrylic acid resins. In general four major categories of ion exchange resins can be distinguished based on the acidic or basic resistance of the functional groups on the surface of the respective resins, that is, strongly acidic, weakly acidic, weakly basic and strongly basic resins. For such anion exchange resins of particular application in the H + form and cation exchange resins in the OH 'form are particularly preferred although other types may also be used. The acid or basic resistance of ion exchange resins is respectively expressed by the pKa value for acid resins and the pKb value for basic resins. Accompanying acid and base dissociation reactions can be written as: (acid dissociation) (2) BOH B + + OH ~ (basic dissociation) For the present invention, the pKa value of acid cation exchange resins is defined as p pH of water by contacting the acid resin thereby the number of functional groups in the form HA is 10 times more than the number of functional groups in the form A. The pKb value of the basic anion exchange resins is defined as the pOH of water contacting the basic resin thereby the number of functional groups in BOH form is 10 times more than the number of functional groups in B + form.

Strongly acidic cation exchange resins have a pKa <3 and, for example, have functional groups of sulphonic acid. Examples of strongly acid cation exchange resins are but limited to Ambeijet 1200 H, 1200 Na, 1500 H, Amberlite IR100 Na, IR120 H, IR120 Na, IR122 Na, SR1L, Amberlite 200C Na, 252 H, 252 Na, 252RF H , 252 H, Imac C16NS, (all from Rohm & Haas), Lewatit Monoplus S100, SI 10 H, S100LF, SP 112, Monoplus SP 112 (all from Bayer), Dowex Monosphere C600 H, C600, Marathon CH, HGRW, HCRS (E0, HCRS H, HCRS, HGR, MSC H, MSC Na 88, Marathon MSC (All from Dow), Diaion SK1B, SK110, PK220 (Mitsubishi), PFC100 H, PCF100, C120E, C100MB H, C100, C100x10, C100E , PF100E, C150H, C150, C150FL, C150TL (all from Purolite), Impact CS398UPS, CS399UPS, C249, C399, CFP110 (All from Sybron).

Weakly acid cation exchange resins have a pka between 3 and 9, for example, have carboxylic acid functional groups. Examples of weakly acidic cation exchange resins are, for example, but not limited to Amberlite IRC 86, IRC50, IRC76, IRC86RF, IRC86SB, Imac HP333, Imac HP336 (all from Rohm & Haas) and Lewatit CNP80, CNP80WS, CNPLF (all Bayer), Dowex MAC3, CCR2, Upcore, MAC3LB (all from Dow), Diaion WK10, WK20, WK40 (all from Mitsubishi) and SR10 and CCP (Sybron).

Weakly basic anion exchange resins have a pKb between 5 and 9 and have, for example, tertiary and quaternary amine functional groups. Examples of weakly basic anion exchange resins are, but not limited to, Amberlite IRA67, IRA67RF, IRA95, IRA96, IRA96RF, IRA96SB, (all from Rohm & Haas), Lewatit PC01072, MP64 (all from Bayer), Dowex MWA1, Monosphere WB500 , MWA1LB (all from Dow), Diaion WA10, WA20, WA30 (all from Mitsubishi), A103S, A845, A847, A845FL, A 100, A100FL, A100DL (all from Purolite), A328, A329 (Sybron).

Strongly basic anion exchange resins have a pKb <6 and have, for example, functional groups of tertiary sulfonium and quaternary phosphonium, quaternary ammonium and quaternary amine. Examples of strongly basic anion exchange resins are, but are limited to, Amberjet 4200 Cl, 4400 OH, 4400 Cl, 4600 Cl, Amberlite IRA402 Cl, IRA402 OH, IRA404 Cl, IRA410 Cl, Ambersep 900 S04, Imac HP555 ( all from Rohm & Haas), Lewatit Monopolus M550, Monopolus M600, M500, M511, M610, VPOC1071, VPOC1073, MP500, Monoplus MP500, MP600, VPOC1074, SN36 (all from Bayer), Monowhere A635, Marathon ALB, Marathon A2, Marathon A2 500, SBRP, SAR, MSA1, Marathon MSA, MSA2 (all from Dow), Diaion SA10A, SA11A, SA20A, PA308, PA312, PA412, PA416 (all from Mutsubishi), PFA400, PFA300, A400, A400MB OH , A420S, A444, A200, A300, A850, A850FL, A870, A500, A500PS, A500FL, A510, A860, A500TL, A52E (all from Purolite), Impact AG IP UPS, AGI UPS, AG2 UPS, ASB1P, ASB2, A641 , A651, A642, SR7 (all from Sybron).

Another type of ion exchange resin is the so-called mixed resin, for example, but not limited to Amberlite MB6113, MB20, MB9L, Lewatit SM92, Dowex MB50, MB500, IND, MB400, MB46 and NM65. Other types of electroactive media include, but are not limited to, zeolite resin material, synthetic activated carbons, hyper-crosslinked sorbent resins such as PUROLITE®HYPERSOL-MACRONET® sorbent resins (trademarks of Purolite, Bala Cynwyd, Pa.) , synthetic carbonaceous adsorbents, such as AMBERSORB® carbonaceous adsorbents (trademark of Rohm & Haas Corporation) and G-BAC® adsorbents (trademark of Kureha Chemical Industry Co., Ltd, Japan), polymeric adsorbent resin beads that are prepared by modified porogen crosslinked copolymer beads, alkylated binding alkalines having micropores in the range of about 0.2 to 0.5 cm3 / cm, mesopores of at least about 0.5 cm3 / g, and total porosity of at least about 1.5 cm 3 / g as disclosed, for example, by Stringfield, US Patent No. 5,460,725, and catalytic carbon as disclosed, for example, by Hayden, US Patent No. 5,444,031, and Matviya et al., n. U.S. Patent No. 5,356,849.

One of the potential problems that can occur while softening feed water and adjusting its pH using electrodeionization is the risk of formation of insoluble Ca deposits. These deposits are formed under conditions of high Ca + 2 concentration and high pH. Then the pH in the ion exchange beds should be kept below 11 to prevent Ca (OH) 2 precipitation and preferably below 9 to prevent CaCO3 'precipitation. Especially when a weakly acidic cation exchange resin is used for water softening, the water pH during the softening steps should preferably be less than 7 to maximize the selectivity for Ca + 2 removal over Na + which is desirable for this request. . However, if a weakly acidic cation exchange resin is used, the pH of the water during the softening process should not be less than 5 in order to maintain an execution force for Ca + 2 exchange with the ions exchanging the resins. which preferably are H + ions. When in the descriptions Ca + 2 is mentioned it should also be clear that another hardness ion, Mg + 2, is indicated.

The present invention is illustrated by the following non-limiting embodiments as schematically shown in Figures 1 to 21. It is noted that these figures provide a schematic representation and are not intended to show an amount and reaction of the various types of preferred resins.

The ratio of different ion exchange resin materials as indicated above is defined as the weight ratio of the ratio of cationic resin material to the weight of anionic resin material in the method of the invention.

In Figure 1, one embodiment of the present invention is illustrated. The feedwater is contacted with one or more assemblies (n = 1, 2, 3, ... n) consisting of a first weakly acidic cation exchange resin and a weakly basic anion exchange resin which are mainly in H + form. and OH 'respectively and which are located within an EDI module. The advantage of using a weakly acidic cation exchange resin to soften water in this application when compared to a strongly acid cation exchange resin is its high selectivity for Ca + 2 over Na + then utilizing its ability to soften more effectively. The weakly basic anion exchange resin will exchange anions for OH "and then the pH of the soft water exiting the EDI module has a pH of about 9. Clearly, the pH will depend on the pKb of the selected basic resin. In cases where n = 2 or higher, the water will be softened more effectively using a weakly acidic cation exchange resin. As Ca + 2 is being removed from the water it is exchanged for H + and then the water will become more acidic. water being soft brings pKa closer to the weakly acidic cation exchange resin, the Ca + 2 liquid exchange will be greatly reduced, limiting the effectiveness of the weakly acidic cationic exchange resin to soften water. will be in the order of 4 and so the pH of the water preferably has to be above about 5 to ensure an effective softening process.After it has come in contact with the weakly acidic cation exchange resin, the mac water ia is subsequently contacted with the weakly basic anion exchange resin which increases the pH of the water. The advantage of applying a weakly basic anion exchange resin is that the pH will never exceed the resin pKb which in the case of weakly basic anion exchange resins can be about 9. This means that the risk of forming calcium deposits as mentioned earlier is reduced. This means that the risk of forming calcium deposits as mentioned above is reduced. In cases where n = 2 or greater, alkaline water is further contacted with the weakly acidic cation exchange resin of the second set. Since the pH of said water is about 9, the weakly acid resin is again capable of exchanging Ca + 2 for 2H + and then more effective water softening can be performed. The ratio of weakly acidic cation exchange resin to weakly acidic anion exchange resin is preferably greater than 1, more preferably greater than 1.5 and even more preferably greater than 2.

[0033] Another embodiment is shown in Figure 2. In this case, the feedwater is first contacted with one or more assemblies (n = 1, 2, 3, ... n) consisting first of a weakly acidic cation exchange resin. and according to a strongly basic anion exchange resin which are mainly in the form H + and OH 'respectively. The ratio between the weakly acidic cation exchange resin and the strongly basic anion exchange resin is preferably greater than 1, more preferably greater than 2 and even more preferably greater than 4 (said ratio for varying for sets n> 2).

Another embodiment is shown in Figure 3. In this case the feedwater is contacted with one or more assemblies (n = 1, 2, 3, ... n) consisting of first a strongly acid cation exchange resin and second a strongly basic anion exchange resin which are mainly in the form H + and OH 'respectively. The ratio of weakly acidic cation exchange resin to strongly basic anion exchange resin is preferably greater than 0.5, more preferably greater than 1 and even more preferably greater than 2 (said ratio for varying for sets n> 2). .

Another embodiment is shown in Figure 4. In this case the feed water is first contacted with a weakly basic anion exchange resin and subsequently with one or more sets (n = 1, 2, 3 .... n) consisting of primarily a weakly acidic cation exchange resin and secondarily a weakly basic anionic exchange resin. The weakly basic cationic exchange resin and the weakly acidic anionic exchange resin are mainly in the form H + and OH "respectively. The advantage of this embodiment is that the pH of the feedwater is already increased before water is contacted with the resin material. Therefore, the level of softening that can be performed during the first contact with the weakly acidic cation exchange is higher than could be obtained if the water enters pH 8 which is common for water. Faucet

In another case, the feedwater is first contacted with a weakly basic anion exchange resin and subsequently with one or more assemblies (n = 1, 2, 3 .... n). ) consisting of a weakly acidic cation exchange resin and a weakly basic anion exchange resin. Also in this embodiment, these exchange resins are mainly in the form H + and OH 'respectively. After leaving the final set of weakly basic and weakly acidic ion exchange resins, soft water is contacted with a strongly basic anion exchange resin to raise the water pH to, for example, 11.0 final pH will clearly depend on pKb. of the strongly basic anion exchange resin. The advantage of operating in this way is that calcium deposits are avoided and even washing water with a pH very suitable for washing can be produced.

In another embodiment (see Figure 6), it is shown that it is not necessary to contact water with a weakly basic anion exchange resin in the final stage of the process as shown in Figure 5. In this case the soft water of the cation exchange resin Weak acid is directly contacted with a strongly basic anion exchange resin.

In another preferred embodiment (shown in Figure 7), the feedwater is contacted with one or more assemblies (n = 1, 2, 3 ... n) consisting of a weakly acidic cation exchange resin and a resin. weakly anionic exchange compounds which are mainly in the form H + and OH 'respectively. After leaving the final set of weakly acidic and weakly acidic ion exchange resins, soft water is contacted with a strongly basic anion exchange resin to raise the water pH to, for example, 11. Final pH Clearly it depends on the pKb of the strongly basic resin selected.

Another preferred embodiment is shown in Figure 8, wherein the feedwater is contacted with a mixed bed consisting of a weakly acidic cation exchange resin and a weakly basic anion exchange resin which are mainly in H + and OH form. "After leaving this mixed bed the soft water is contacted with a weakly basic anion exchange resin to raise the water pH to, for example, 9. Using a mixed bed of a weakly acidic cation exchange resin and a weakly anionic exchange resin, the soft water pH can be kept within the desired pH range of about 5 to about 9. So an optimal Ca + 2 removal is combined with a reduced risk for calcium deposit formation. The ratio of the weakly acidic cation exchange resin to the weakly basic anionic exchange resin is preferably greater than 1, more preferably greater than 1.5 and even more preferred is greater than 2.

Alternatively, after leaving such a mixed bed the soft water may be contacted with a strongly basic anion exchange resin in order to raise the water pH to a value of, for example, 11 (see Figure 9).

Another embodiment is shown in Figure 10 in which the feedwater is contacted with a mixed bed consisting of a weakly acidic cation exchange resin and a strongly basic anion exchange resin which are mainly in H + and OH form respectively. After leaving this mixed bed the soft water is contacted with a weakly basic cation exchange resin to raise the water pH to, for example, 9. Using a mixed bed of a weakly acidic cation exchange resin and a Strong acid anion exchange at the appropriate ratio, the pH of the water being soft can be kept within the desired pH range of about 5 to about 9 and then optimal Ca + 2 removal is combined with a reduced risk for deposit formation. The ratio of the weakly acidic cation exchange resin to the strongly basic anion exchange resin is preferably greater than 1, more preferably greater than 2 and even more preferred greater than 4.

Alternatively, after leaving such a mixed bed the soft water may be contacted with a strongly basic anion exchange resin to raise the water pH to, for example, 11 (see Figure 11). The ratio of the weakly acidic cation exchange resin to the strongly basic anion exchange resin is preferably greater than 1, more preferably greater than 2 and even more preferably greater than 4.

In another embodiment (as shown in Figures 12 and 13), soft water is first contacted with a strongly acid cation exchange resin and then with a weakly basic anion exchange resin to raise the pH of the soft water. for, for example, 9 or with a strongly basic anion exchange resin. The relationship between the strongly acid cation exchange resin and the weakly basic anion exchange resin is preferably greater than 1, more preferably greater than 0.5 and even more preferred greater than 2. Another embodiment (see Figure 14) is feed water. It is first contacted with a mixed bed consisting of weakly basic anion exchange and strongly acid cation exchange resins which are in the form H + and OH 'respectively. After leaving the mixed bed the soft water is contacted with a weakly basic anion exchange resin in order to raise the water pH to, for example, 9. Alternatively, after leaving the mixed bed the soft water may be contacted with a soft water resin. strongly basic anion exchange in order to increase the pH of the wash water to, for example, 11 (see figure 15). The relationship between the strongly acid cation exchange resin and the weakly basic anion exchange resin is in the mixed bed is greater than 1, more preferably greater than 1.5 and more preferably greater than 2.

Another embodiment (see Figure 16) is that the feedwater is first contacted with a mixed bed consisting of strongly acidic cation exchange resins and strongly basic anion exchange resins which are mainly in the form H + and OH "respectively. After leaving this bed mixed with soft water is contacted with a weakly basic anion exchange resin to raise the water pH to, for example, 9. The relationship between the strongly acid cation exchange resin and the strongly basic anion exchange resin is in the bed. is preferably greater than 1, more preferably greater than 1.5 and more preferably greater than 2. Alternatively (Figure 17), after leaving the mixed bed soft water may be contacted with a strongly basic anion exchange resin in order to increase the pH of the wash water to, for example, 11.

As mentioned above, for special cleaning purposes or other purposes it may be advantageous to produce acidic wash water of, for example, pH 5. The pH of the acidic wash water is preferably greater than 3, more preferably greater than 4 and even more preferred is greater than 5 but less than 7.5.

In yet another embodiment (see Figure 18), the feedwater is contacted with a mixed bed consisting of weakly acidic and weakly basic anionic exchange resins which are mainly in the form H + and OH "respectively. The resulting scrubber has a reduced hardness and a pH of about 5 to 6 depending on the respective pKa and pKb of the weakly basic and weakly acidic ion exchange resins and the relationship between them.The relationship between the weakly acidic cation exchange resin and the resin The weakly basic anion exchange rate is in the mixed bed greater than 1, more preferably greater than 1.5 and more preferably greater than 2.

In a preferred embodiment (see Figure 19), the feedwater is contacted with a mixed bed consisting of weakly acidic and strongly basic anionic exchange cation resins which are mainly in the H + and OH 'form respectively. The resulting wash water has a reduced hardness and the pH may range from 5 to even 9 depending on the respective pKa and pKb of the strongly basic and weakly acidic ion exchange resin and the relationship between them. The relationship between the weakly acidic cation exchange resin and the strongly basic anion exchange resin is in the mixed bed greater than 1, more preferably greater than 2 and more preferably greater than 4.

In yet another embodiment (see Figure 20), the feedwater is contacted with a mixed bed consisting of strongly acidic and weakly basic anionic exchange resins which are mainly in the H + and OH 'form respectively. The resulting wash water has a reduced hardness and the pH may range from 3 to even 9 depending on the pKa and pKb of the weakly basic and strongly acidic ion exchange resin and the relationship between them. The relationship between the weakly acidic cation exchange resin and the weakly basic anionic exchange resin is in the mixed bed is greater than 0.5, more preferably greater than 1 and more preferably greater than 2.

In another embodiment (see Figure 21), the feedwater is contacted with a mixed bed consisting of strongly acidic cation exchange resins and strongly basic anion exchange resins which are mainly in the form H + and OH "respectively. The resulting wash has a reduced hardness and the pH may range from 3 to even 9 depending on the pKa and pKb of the weakly basic and strongly acidic ion exchange resin and the relationship between them.The relationship between the weakly acidic cation exchange resin and the resin The weakly basic anion exchange rate is in the mixed bed is greater than 0.5, more preferably greater than 1 and more preferably greater than 2.

Contact time of water being treated and ion exchange resins is an important parameter. The contact time for the present invention is defined as the ratio between the total volume of the combined ion exchange resins contacting the water being treated and the flow rate of said water.

Contact Time [s] = total resin volume contacting water [L] / water flow [L min'1].

For reasons of minimizing equipment costs and size, the total volume of ion exchange resins is kept as low as possible. However, sufficient water contact time with ion exchange resins is required to allow the ion exchange reaction partially but not completely to occur. So the total resin volume depends on the hardness of the feedwater and will be at least 0.11 for very low water hardness and at most 4 1 for very high water hardness. The total resin volume contacting the water being treated is preferably less than 4 L, more preferably less than 3 L and even more preferably less than 21 L, but greater than 0.11 L.

Another consideration is the fill rate of the treated water within the apparatus, which is preferably greater than 0.25 L. min'1 for reasons of convenience to the user. Maximum flow is limited by the maximum fill rate of a regular tap connection which is given were 15 L. min'1. The preferred fill rate is greater than 0.25 L. min'1, more preferably greater than 1.0 L. min'1 and even more preferably greater than 2 L. min'1, but less than 15 L. min " 1.

Based on these considerations the contact time as defined above should preferably be greater than 0.01 min, more preferably greater than 0.1 min and even more preferably greater than 0.3 min, but less than 2 minutes.

Another important process parameter for the present invention is the maximum allowable pressure drop on the water treatment device. The pressure drop will especially be determined by the size of the resin particles that are present, that is, the smaller the particle size, the larger the pressure drop. On the other hand, the smaller the particle size, the larger the contact area of resin with water will be per unit volume. Resin particle diameter is defined as the ratio between the volume and the outer surface area of the resin particle. Based on these considerations, the average particle size of the ion exchange resins is preferably greater than 0.05 mm, more preferably greater than 0.1 mm and even more preferably greater than 0.5 mm but less than 10 mm. In this respect also the porosity in the ion exchange compartments is an important criterion. The porosity in this case is defined as: Porosity [-] = volume of ion exchange material [L] / volume of compartment containing ion exchange resins [L], [0057] For reasons of limiting pressure drop while minimizing pressure. The volume of the ion exchange resin container porosity is preferably less than 0.8, more preferably less than 0.6 and preferably greater than 0.2. The Cleaning Method In the cleaning method of the invention, the water of The improved wash obtained as a consequence of the water treatment step (i) is mixed in step (ii) with a low environmental impact detergent (LEIP) and used to treat substrates to be cleaned. Said cleaning method is preferably performed in a dishwasher or fabric washer. Replenishers It is estimated that most laundry detergent products sold in most parts of the world are conventional granular detergent products. These typically comprise more than 15% by weight of a reinforcer. Reinforcers are added to improve detergency, but reinforcers such as phosphate are recognized for their effects on eutrophication. To overcome this problem in many countries - particularly those where phosphates are banned, zeolites have become the accepted industrial model. The LEIP used according to the invention is substantially free of reinforcer. Substantially free of reinforcer for the purpose of the present invention means that LEIP comprises 0 to 5% by weight of reinforcer of the total LEIP composition. Preferably, LEIP comprises 0 to 3 wt%, more preferably 0 to 1 wt%, even more preferably 0 wt% reinforcer of the total LEIP composition.

Reinforcing materials are, for example, 1) calcium sequestering materials, 2) calcium precipitating materials, 3) calcium ion exchange materials and 4) mixtures thereof.

Examples of calcium sequestering reinforcing materials include alkali metal polyphosphates, such as sodium tripolyphosphate; nitrilotriacetic acid and its water soluble salts; alkali metal salts of carboxymethyloxy succinic acid, ethylene diamine tetracetic acid, oxisuccinic acid, melitic acid, benzene polycarboxylic acid, citric acid; and polyacetal carboxylates as disclosed in U.S. Patent Nos. 4,144,226 and 4,146,495 and dipicolinic acid and its salts. Examples of precipitation enhancing materials include sodium orthophosphate and sodium carbonate.

Examples of calcium ion exchange reinforcing materials include the various types of water-insoluble amorphous or crystalline aluminosilicates, of which zeolites are the best known representatives, for example zeolite A, zeolite B (also known as Zeolite P), zeolite Q, zeolite X, zeolite Y and also the type of: Zeolite P as described in EP-A 0384070. In addition to the polymeric reinforcers such as polyacrylate and polymaleates. Although soaps may have a reinforcing function for the purpose of the present invention soaps are not considered to be reinforcers, but surfactants.

Surfactants The LEIP used in the cleaning method of the invention comprises at least 10 wt%, preferably at least 25 wt%, more preferably 40 wt% of a surfactant. In most cases, any surfactant known in the art may be used. The surfactant may comprise one or more anionic, cationic, nonionic, zwitterionic surfactant and mixtures thereof. Other examples are given in “Surface Active Agents and Detergents” (Vol. I and II by Schwartz, Perry and Berch). A variety of such surfactants are also generally disclosed in U.S. Patent No. 3,929,678, filed December 30, 1975 to Laughlin, et al., At column 23, line 58 through column 29, line 23.

PH modifier

Another major ingredient in conventional granular detergent products is pH modifiers. For the purpose of the present invention the term pH modifier means describing ingredients that affect pH or increasing, decreasing or maintaining pH at a certain level. Typical examples include, but are not limited to, salts such as acetates, borates, carbonates, (di) silicates, acids such as boric acid, phosphoric acid, sulfuric acid, organic acids such as citric acid, bases such as NaOH, KOH, organic bases such as amines (mono- and tri-ethanol amine).

In a pH modifier and enhancer of conventional detergent products up to 70% by weight of the composition may be considered. It is to be noted that for the purpose of the present invention surfactants - although some surfactants may have some pH effect they are not considered a pH modifier. LEIP according to a preferred embodiment of the invention is substantially free of the pH modifier. Substantially pH modifier free means describing products comprising 0 to 5% by weight of the pH modifier; Preferably the LEIP comprises 0 to 3 wt%, more preferably 0 to 15 wt%, more preferably 0 wt% pH modifier of the total LEIP composition.

Enzymes Enzymes constitute a preferred component of LEIP. Enzyme selection is left to the formulator. However, the examples below illustrate the use of enzymes in LEIP compositions according to the present invention. “Detergent enzyme, as used herein, means any enzyme having a cleaning effect, stain removal or otherwise beneficial effect on a LEIP. Preferred enzymes for the present invention include, but are not limited to, but are not limited to, proteases, celluases, lipases, amylases and peroxidases.

Enzyme Stabilizing System The LEIP herein may comprise from about 0.001% to about 10% by weight of the LEIP of an enzyme stabilizing system. One embodiment comprises from about 0.005% to about 4% by weight of the LEIP of said system, while another aspect includes the range from about 0.01% to about 3% by weight of the LEIP of an enzyme stabilizing system. The enzyme stabilizer system may be any stabilizer system which is compatible with the detergent enzyme. Stabilizer systems may, for example, comprise calcium ion, boric acid, propylene glycol, short chain carboxylic acids, boronic acids, and mixtures thereof, and are designed to address different stabilization problems depending on the type and physical form of the detergent composition.

Bleaching System The LEIP composition used in the method of the present invention may optionally include a bleaching system. Nonlimiting examples of bleaching systems include hypoalite bleaches, peroxygen bleaching systems with or without a transition and / or organic metal catalyst, or transition metal peroxygen systems. Peroxygen systems typically comprise a "bleaching agent" (hydrogen peroxide source) and a "activator" and / or "catalyst", however, preformed bleaching agents are included Catalysts for peroxygen systems may include In addition, certain transition metal complexes are capable of providing a bleaching system without the presence of a hydrogen peroxide source.

Optional Cleaning Agents [0071] LEIP may contain one or more optional cleaning agents. Cleaning agents include any agent capable of improving the cleanliness, appearance, condition and / or care of clothing. Generally, the cleaning agent may be present in the compositions of the invention in an amount from about 0 to 20 wt%, preferably 0.001 wt% to 10 wt%, more preferably 0.01 wt% to 5 wt%. weight of total LEIP composition.

Some suitable cleansing agents include, but are not limited to, antibacterial agents, colorants, perfumes, pro-perfumes, finish aids, lime soap dispersants, composition odor control agents, odor neutralizers, polymeric dye transfer inhibitors, crystal growth inhibitors, anti-stain agents, antimicrobial agents, anti-oxidants, anti-decomposition agents, dirt-releasing polymers, thickeners, abrasives, corrosion inhibitors, soap water stabilizing polymers, process aids fabric softening agents, optical brighteners, hydrotropes, suds and suds suppressors, suds or suds reinforcers, antistatic agents, dye fixatives, dye abrasion inhibitors, crease reducing agents, crease resistant, dirt repellent agents, sunscreen agents, anti-fade agents, and their mixtures.

Product Format LEIP can be dosed in any suitable format such as a liquid, gel, paste, tablet or sachet. In some cases granular formulations may be used although this is not preferred. In a preferred embodiment LEIP is a non-aqueous product. Non-aqueous for the purpose of the present invention means to describe a product comprising less than 10 wt%, preferably less than 5 wt%, more preferably less than 3% free water. The non-aqueous product may be a liquid, gel or paste or encapsulated in a sachet.

It has been suggested to equip washing machines with one or more detergent product containers so that the detergent product can be dispensed automatically as described in EP-A-0419036. LEIP can be dosed from a single container. Alternatively, the ingredients constituting the LEIP may be dosed from the separate containers as described in EP-A 0419036. Thus in a preferred embodiment at least one LEIP ingredient is automatically dosed. An advantage of a LEIP may be that the reduced number and / or quantity of ingredients allows for a much larger volume of detergent product. In practice this would mean that the consumer does not need to refill the containers as often or that the containers may be smaller.

The present invention will be illustrated with reference to the following non-limiting examples, the parts and percentages of which are by weight unless otherwise indicated.

Examples 1, A and B

Improved wash water (WAW) was produced as follows: Mains water (having a French hardness of 16ΎΗ, and a pH value of 8.2) was contacted with a suitable combination. of ion exchange resins, as shown in figure 2 where n = 2, The applied cation exchange resin was Dowex MAC-3 (ex. Dow) and the anion exchange resin applied was Ambeijet 4400 OH (ex Rohm & Haas). These resin materials were applied at a ratio of 2.5 and their total bed volume was 600 ml. The flow rate over the resins was 21 min -1. By contacting the feed water with said combination of ion exchange resins improved wash water with a hardness of 1ΎΗ and a pH of 10.8 was produced. [0078] In example 1, the LEIP cleaning performance using the WAW thus produced was tested as follows: About 15 l of WAW was fed into a normal tissue washer (Miele, type W765). LEIP was pre-dissolved in 1 l of WAW such that an aqueous detergent formulation was obtained consisting of WAW, NaLAS (> 95% pure, eg Degussa Huls) at a concentration of 1.0 g L'1, Savinasse 12TXT (eg Novozymes) at a concentration of 0.05 g.L'1 and a DC8010 foam depressant (ex. Dow) at a concentration of 12 mg.L'1. The resulting aqueous LEIP-containing formulation was added to the fabric washer.

The loading of the washing machine consisted of 3 kg of clean white cotton fabric and 4 fabric samples from each of the following dirt monitors (eg CFT bv., Vlaardingen, The Netherlands). • M002 (gram on cotton fabric) • WFK 10D (tallow on cotton fabric) • CS-126 (diluted lipstick on cotton fabric) • EMPA 106 (carbon black / mineral oil on cotton fabric) • AS-9 (Pigment / Oil / Milk on Cotton) Loading was used with the LEIP-containing formulation at a temperature of 40 ° C using the Miele washing machine's normal “whitewashing program”.

In Example A, a wash experiment was performed using 15 l of tap water (having 16 ° FH and a pH value of 8.2) instead of WAW. Same wash load and wash program. In this experiment, a formulation containing LEIP was used having the same composition as example 1, although the WAW in said formulation was replaced by said tap water.

Finally, in Example B a wash experiment was performed using 16 l of tap water (having 16 ° FH and a pH value of 8.2), and a commercial detergent product. In addition, the same wash load and wash program were used as in examples 1 and A. The composition of this commercial detergent product is as follows: INGREDIENT% BY WEIGHT

Surfactants 15 Zeolite Booster 25 Buffers 50 Enzymes 0.5 Anti-Foam 2 Polymers 0.5 Other (Including Perfume) 2.5 Water 4.5 [0084] The corresponding cleaning results for the various dirt monitors in the three The results of cleaning are expressed as 'Delta R460 *', which is the difference in reflectance of dirt monitors after and before the washing experiment, as measured with a spectrophotometer (type 968, X- Rite) at 460 nm.

Figure 22 clearly shows that the cleaning performance of the LEIP-containing formulation with regular tap water (comparative example A) is significantly worse than the cleaning performance of LEIP in combination with WAW for all monitors tested. In addition, the cleaning performance of the LEIP-containing formulation in combination with WAW appears to be comparable to that of a commercial tap water detergent formulation (comparative example B).

Claims

Claims (21)

A cleaning method, characterized in that it comprises the steps of: (i) contacting feed water successively with one or more sets of a first cation exchange resin material and secondly an anion exchange resin material so as to producing improved wash water (WAW) having a water hardness of less than 5 ° FH and a pH value that is greater than 0.5 pH units different from that of the feedwater, said pH value being greater than 8, 5, according to which resins are regenerated using an electric field; (ii) mixing said WAW with a low environmental impact detergent (LEIP) product comprising 0 to 5 wt% reinforcer and comprising at least 10 wt% surfactant to obtain a wash liquor; and (iii) treating substrates to be cleaned with said wash liquor. Cleaning method according to claim 1, characterized in that the feed water is tap water having a water hardness of at least 7 ° FH. A cleaning method according to any one of claims 1 to 2, characterized in that said cationic resin materials comprise exchange resins which are in H + form. A cleaning method according to any one of claims 1 to 3, characterized in that said anionic resin material comprises exchange resins which are in the OH 'form; A cleaning method according to any one of claims 1 to 4, characterized in that one or more bipolar membranes (s) are applied to facilitate the regeneration of ion exchange resins. Cleaning method according to any one of claims 1 to 5, characterized in that the resins are regenerated using electrodeionization (EDI). A cleaning method according to any one of claims 1 to 6, characterized in that said cation exchange resin is a weakly acidic resin. A cleaning method according to any one of claims 1 to 6, characterized in that the cation exchange resin is a weakly acid resin and the anion exchange resin is a strongly basic resin. A cleaning method according to any one of claims 1 to 6, characterized in that said cation exchange resin is a weakly acid resin and said anion exchange resin is a weakly basic resin. A cleaning method according to any one of claims 1 to 6, characterized in that said cation exchange resin is a strongly acidic resin and said anion exchange resin is a strongly basic resin. A cleaning method according to any one of claims 1 to 6, characterized in that the cation exchange resin is weakly acidic and the anionic exchange resin is weakly basic, and the feed water is first contacted with a weakly anionic exchange resin, prior to step (i) of said method. Cleaning method according to any one of claims 1 to 11, characterized in that the conductivity of the feedwater is more than 50 micro Siemens cm-1. Cleaning method according to any one of claims 1 to 12, characterized in that the hardness of WAW is less than 2 ° FH, preferably less than 1 ° FH. A cleaning method according to any one of claims 1 to 13, characterized in that the pH of the WAW is greater than 9.5. A cleaning method according to any one of claims 1 to 14, characterized in that the total volume of resin material contacted by the water being treated is less than 4 L. Cleaning method according to any one of Claims 1 to 15, characterized in that the flow rate of the feed water is greater than 0,25 L.min "1. Cleaning method according to any one of Claims 1 to 16, characterized in that the contact time between feed water and resin material is greater than 0.01 min. A cleaning method according to any one of claims 1 to 17, characterized in that the average particle size of the ion exchange resins is greater than 0.05 mm. A cleaning method according to any one of claims 1 to 18, characterized in that the porosity of the ion exchange compartments containing the resin material is less than 0.8. A cleaning method according to any one of claims 1 to 19, characterized in that the LEIP comprises 0 to 5% by weight of pH modifier. Cleaning method according to any one of claims 1 to 20, characterized in that step (iii) of said method is performed in a household cleaning apparatus.