WO2004005631A1

WO2004005631A1 - System, liquid composition and method for cleaning and disinfecting a toilet bowl

Info

Publication number: WO2004005631A1
Application number: PCT/IT2002/000440
Authority: WO
Inventors: Giancarlo Gazzaniga
Original assignee: Deoflor S.P.A; Perazzo, Livia
Priority date: 2002-07-03
Filing date: 2002-07-03
Publication date: 2004-01-15
Also published as: AU2002368083A1

Abstract

A system (1) is described for cleaning and disinfecting a toilet (2) comprising a container (3) of a liquid composition (L), said container (3) being closed in a substantially fluid-tight manner; valve means (7) co-operating with an outlet opening (17) for said liquid composition (L), said outlet opening (17) being formed in the container (3) and operated at each flushing operation by the water introduced into the bowl (2) for delivering dosed amounts of the liquid composition (L); wherein the liquid composition (L) is stored in the container (3),.has a viscosity at 20°; C of from 25 to 500 mPa.s and comprises a) from 15 to 70% by weight of an oxidizing agent selected from the agents adapted to release a halogen or oxygen when contacted with water, and mixtures thereof; b) from 1 to 25% by weight of a cleaning agent comprising at least one surfactant selected from the group comprising the anionic, cationic, non-ionic or amphoteric surfactants compatible with the oxidizing agent, said cleaning agent being such as to form, in combination with the oxidizing agent, a liquid composition (L) capable of mixing with the flushing water introduced in toilet bowl (2) without forming hydration complexes or micelles during the flushing operations of said water; and c) an effective amount of at least one pH-stabilizing agent adapted to adjust the pH of the liquid composition (L) at a value such as to maintain the oxidizing agent substantially stable.

Description

Title: System, liquid composition and method for cleaning and disinfecting a toilet bowl

DESCRIPTION Background of the invention

According to a general aspect thereof, the present invention relates to a system for cleaning and disinfecting a toilet bowl of the type comprising: a) a container of a liquid composition, said container being closed in a substantially fluid-tight manner; b) valve means cooperating with an outlet opening for said liquid composition, said outlet opening being formed in the container for delivering dosed amounts of said liquid composition, said valve means comprising an opening device operable at each flushing operation by the water introduced into the bowl.

The invention also relates to a liquid composition for use in such a system, as well as to a method for cleaning and disinfecting a toilet bowl and to a kit of separate parts for combined use for cleaning and disinfecting a toilet bowl. In the following description and in the subsequent claims, the expression "liquid composition" is used to indicate a liquid substance having cleaning and/or descaling properties and/or disinfecting/bleaching and/or perfuming activity.

Prior Art

As is known, in the field of devices for delivering liquid compositions into a toilet bowl, it has always been felt the need of delivering a constant amount of composition at each flushing independently of the amount of liquid present in the container and of the frequency of the flushing operations.

It goes without saying that the amount of liquid composition delivered must also be able to ensure the achievement in a satisfactory manner of the cleaning, foaming, descaling, disinfecting, bleaching or perfuming effect for which the composition has been specifically formulated.

Regarding this, it should be noted that particularly desirable effects in the case of a liquid composition intended for use into a toilet bowl are the disinfecting/bleaching effect, which is generally obtained thanks to the presence in the composition of one or more oxidizing agents capable of releasing into the water highly reactive compounds, such as for example hypoalose acid, hypoalitic ions or active oxygen, and the cleaning/foaming effect, which is obtained thanks to the presence in the composition of one or more surfactants soluble in water and compatible with the oxidizing agent. In the following description and in the subsequent claims, the expression "surfactant compatible with the oxidizing agent" is used to indicate a surfactant which is suitably formulated to be able to coexist with the oxidizing agent in the same liquid composition without causing degrading phenomena of the surfactant or of the oxidizing agent. In order to satisfy the aforementioned need, it has been proposed, as described in international PCT patent application WO 01/06067 filed by the same Applicant, the use of a mechanical delivery system to be suspended from the rim of a toilet bowl and comprising, in a supporting structure, a container of a liquid composition, said container being closed in a substantially fluid-tight manner, and valve means adapted to deliver dosed amounts of the liquid composition stored in the container. More specifically, the valve means cooperate with an outlet opening for the liquid composition, said outlet opening being formed in the container, and release a predetermined amount of the liquid composition at each flushing of water into the bowl by means of an opening device which is in turn operated by the flushing water itself. Although in principle the delivery of dosed amounts of liquid composition adapted to give, at each flushing, the desired cleaning/foaming and disinfecting/bleaching effects does not seem to cause problems, it has been found in practice that delivery systems including a container which can be hooked to a toilet bowl, whether based upon a metering system of the mechanical type or not, have intrinsic features such that the liquid composition to be delivered must have specific additional requirements usually conflicting with each other. Thus, for example, the concentration of active substances in the liquid composition for an effective cleaning/foaming and disinfecting/bleaching effect must be much higher with respect to the concentration employed in other types of products present on the market for cleaning toilets and delivered manually on the surfaces thereof. In particular, mechanical delivery systems must be sized in such a way as to deliver, at each flushing, a limited amount of composition, which must be however effective for the predetermined purposes and generally in the order of 0.1-0.2 ml, for ensuring the duration of use required by the market for one charge of liquid composition (usually 250-550 flushes with a container having a capacity of about 50-55 ml). Nevertheless, such high concentrations of active substances (surfactant and oxidizing agent) usually turn out to be not very compatible with the stability of the liquid composition required by the market both during storage and during use, but, above all, they are not very compatible with the achievement of the viscosity values of the composition which make it possible to mechanically deliver the aforementioned limited amounts at each flushing operation. A too low viscosity value could, in fact, lead to a quick consumption of the charge contained in the container, whereas, on the opposite, a too high viscosity value could hinder the operation of the dosing valve means which therefore would deliver a too small amount of composition, thus unacceptably compromising the operation of the mechanical delivery system. Summary of the invention The technical problem underlying the present invention is therefore that of providing a system for cleaning and disinfecting a toilet bowl based upon a metering system of the mechanical type which is capable to ensure both a constant and regular delivery of dosed amounts of liquid composition suitable for obtaining the desired cleaning/ foaming and disinfecting/bleaching effects at each flushing, and a sufficient stability of the liquid composition during use and during storage.

According to the present invention, it has now surprisingly been found that the sought compromise between the desired features of stability and viscosity of the liquid composition and the desired delivery of amounts suitable for obtaining a satisfactory cleaning/foaming and disinfecting/bleaching effect for the whole duration of the charge can be achieved by combining in the liquid composition to be used with the aforementioned metering system of the mechanical type: a) an oxidizing agent selected from the agents adapted to release a halogen or oxygen when contacted with water, and mixtures thereof; b) a cleaning agent consisting of a specific class of anionic, cationic, non-ionic or amphoteric surfactants compatible with said oxidizing agent and such as to form, in combination with the oxidizing agent, a liquid composition capable of mixing with the flushing water introduced into the toilet bowl without forming hydration complexes or micelles during the flushing operations of said water; and - an effective amount of at least one pH-stabilizing agent adapted to adjust the pH of the liquid composition at a value such as to maintain the oxidizing agent substantially stable.

The invention therefore provides a system for cleaning and disinfecting a toilet bowl as defined by attached claim 1. In the present description and in the subsequent claims, each time a given physical parameter or concentration parameter is expressed by a range of values, such abbreviation is used to indicate also all possible intermediate values between the extremes of the range given for the relevant parameter.

According to the invention, it has been found that in order to achieve a regular delivery of the desired dose (0.1-0.2 ml) of liquid composition by the mechanical delivery system, the viscosity at 20°C of the composition as a whole must be from 25 to 500 mPa-s (these being limits outside of which the composition is too fluid and, therefore, not very effective and long-lasting or, respectively, too viscous and, therefore, difficult or impossible to be delivered in the small amounts provided by the mechanical delivery system).

Preferably, the viscosity at 20°C of the liquid composition is from 25 to 250 mPa-s and, still more preferably, from 40 to 150 mPa-s.

It has been observed, in fact, that when the viscosity of the composition falls within such preferred ranges of values, the delivery by the mechanical system is particularly regular, constant and repeatable in time during the use of the system.

The Applicant has found that such viscosity values are advantageously obtainable by combining together the ingredients which shall be described hereinbelow. Oxidizing agent According to the present invention, the high-concentration oxidizing agent (up to 70% by weight to the total weight of the composition) performs a disinfecting/bleaching function and for such a purpose consists of suitably formulated reactive compounds in liquid phase capable of releasing, when contacted with the flushing water, highly oxidizing compounds. According to the present invention, the oxidizing agent is selected from the agents adapted to release a halogen or oxygen when contacted with water, and preferably from the group comprising hypohalogenites of alkaline or alkaline-earth metals and precursors thereof, peroxy-compounds and precursors thereof, and mixtures thereof. Still more preferably, the oxidizing agent in liquid phase is selected from the group comprising: hypochlorites of alkaline or alkaline-earth metals, in particular sodium hypochlorite and calcium hypochlorite, precursors of hypochlorites, such as for example organic and inorganic chloramines, in particular chloramine T, di- and trichloro isocyanurate acids and the salts of alkaline or alkaline-earth metals thereof, hydrogen peroxide, perborates of alkaline or earth-alkaline metals, in particular sodium and potassium perborates, persulfates of alkaline or earth-alkaline metals, in particular sodium and potassium persulfates, percarbonates of alkaline or earth-alkaline metals, in particular sodium and potassium percarbonates, organic peroxides, such as for example peroxycarboxylic acids and peracetic acid.

For the purposes of the invention, and in order to achieve the aforementioned disinfecting/bleaching effects, the amount of the oxidizing agent is from about 15% to about 70% by weight to the total weight of the composition, this percentage being used to indicate the percentage of the commercial solutions, available on the market, of the specific substance(s) capable of releasing halogens or nascent oxygen. For merely illustrative purposes, such commercial solutions of a substance capable of releasing halogen or nascent oxygen may consist of 14/15 v/v solutions of sodium hypochlorite or, respectively, of 35% w/w solutions of hydrogen peroxide.

Preferably, the amount of oxidizing agent is from about 15% to about 60% by weight to the total weight of the composition and, still more preferably, from about 20% to about 50%) by weight to the total weight of the composition. In the preferred case in which the oxidizing agent essentially consists of a 14/15 v/v solution of sodium hypochlorite, such ranges correspond to the following percentages of active chlorine, determined by analytic methods known in the art: respectively 1.5-8.4% (15-70% by weight of oxidizing agent), 1.5-7.2% (15-60% by weight of oxidizing agent) and 2.4-6% (20-50% by weight of oxidizing agent). Cleaning agent According to the present invention, the high-concentration cleaning agent (up to 25% by weight to the total weight of the composition) performs a cleaning/foaming function and for such a purpose consists of at least one anionic, cationic, non-ionic or amphoteric surfactant having the features of compatibility with the oxidizing agent in the sense defined above while being such as to form, in combination with the oxidizing agent, a readily soluble liquid composition, in such a way that the latter can be delivered in a constant, regular and repeatable manner by the mechanical delivery system. More particularly, the suitable surfactant(s) of the present the invention must be capable of forming, in combination with the oxidizing agent, a liquid composition adapted to mix with the flushing water introduced into the bowl without forming hydrating complexes or micelles in the limited delivery time running between the start and the end of the flushing operations in the toilet bowl.

In the present description and in the subsequent claims, the term "readily soluble liquid composition" is used to indicate a liquid composition capable of forming a substantially single-phase mixture when mixed with water, i.e. capable of mixing with water without forming hydration complexes or micelles which instead would result in a two-phase mixture, which in this case is undesired since this would hinder an effective metering of the surfactant in the water, thus reducing the cleaning/foaming effectiveness thereof. For the purposes of the invention, a solubility index can be conveniently determined experimentally according to the following method. An amount equal to about 1 g of the liquid composition, to which a compatible dyestuff has been previously added to better detect the dissolution thereof, is put in a 10 ml cylinder which is then filled with water and closed by a lid. Subsequently, the cylinder is overturned by 180° for "n" times until a solution dyed in a uniform manner is obtained. On the basis of the aforementioned method, the number "n" of overturning operations of the cylinder is therefore taken as the value of the aforementioned solubility index.

In the present invention, a liquid composition shall be considered readily soluble when the number "n" of overturning operations of the cylinder is less than 20, preferably from 2 to 14 and, still more preferably, from 3 to 10. Furthermore, in a preferred embodiment of the invention, the surfactant(s) constituting the cleaning agent of the composition can advantageously perform not only the aforementioned cleaning/foaming function, but also the additional function of adjusting the viscosity of the liquid composition maintaining the latter within the maximum limit of 500 mPa-s (as measured at 20°C). For such a purpose, the surfactant(s) constituting the cleaning agent of the liquid composition of the invention are preferably selected not only from those having the features defined above, but also from those capable of adjusting the viscosity at 20°C of the liquid composition - once mixed with the remaining ingredients and, particularly, once mixed with the oxidizing agent which shall be described hereinbelow - from 25 to 500 mPa s.

Preferably, the surfactant(s) suitable for use in the liquid composition of the invention are capable of adjusting the viscosity at 20°C of the liquid composition - once mixed with the remaining ingredients - from 25 to 250 mPa-s and, still more preferably, from 50 to 150 mPa s. For the purposes of the invention and in order to achieve the aforementioned cleaning/foaming effects and, preferably, the effect of adjusting the viscosity, the amount of cleaning agent is from about 1% to about 25% by weight to the total weight of the composition.

Preferably, the amount of cleaning agent is from about 5% to about 20% by weight to the total weight of the composition and, still more preferably, from about 8% to about 18% by weight to the total weight of the composition.

Preferably, the anionic surfactants of the invention are selected from the group comprising alkylsulfates of an alkaline or earth- alkaline metal comprising from 8 to 16 carbon atoms, linear or branched alkylethersulfates of an alkaline or earth-alkaline metal comprising from 8 to 16 carbon atoms and from 2 to 4 ethylene oxide (EO) units, and mixtures thereof.

Among these anionic surfactants, for the purposes of the invention, sodium laurylsulfate, sodium laurylethersulfate comprising 2 EO units and sodium laurylmyristylethersulfate comprising 4 EO units are particularly preferred. Preferably, the non-ionic surfactants of the invention are selected from the group comprising linear or branched ethoxylate alcohols comprising from 12 to 16 carbon atoms and from 4 to 11 ethylene oxide (EO) units.

Preferably, the amphoteric surfactants of the invention are selected from the group comprising linear or branched amine oxides comprising from 8 to 16 carbon atoms. More specifically, such amine oxides have a non-ionic behaviour at basic pH and a cationic behaviour at acid pH.

Among these amine oxides with amphoteric behaviour (non-ionic behaviour in a basic field and cationic behaviour in an acid field), for the purposes of the invention, linear or branched dimethyl-N-(alkyl)amine oxides comprising from 8 to 16 carbon atoms and, still more preferably, dimethyl-N-(lauryl-myristyι)arnine oxide and coco dimethyl amine oxide are particularly preferred.

In a preferred embodiment and in order to obtain a voluminous, abundant and long- lasting foam, the cleaning agent of the liquid composition comprises at least one non- ionic or amphoteric surfactant and at least one anionic surfactant. More preferably, said at least one non-ionic or amphoteric surfactant is a linear or branched dimethyl-N-(alkyl)amine oxide comprising from 8 to 16 carbon atoms, whereas said at least one anionic surfactant is a linear or branched alkylethersulfate of an alkaline or earth- alkaline metal comprising from 8 to 16 carbon atoms and from 2 to 4 ethylene oxide (EO) units. In a preferred embodiment, the weight ratio between the aforementioned at least one non-ionic or amphoteric surfactant and the aforementioned at least one anionic surfactant is from 1 to 25.

Preferably, the aforementioned weight ratio is from 2 to 20 and, still more preferably, from 3 to 18. In such a way, it is possible to obtain liquid compositions which satisfy the required different functional requirements. pH-stabilizing agent

For the purposes of the invention and in order to achieve the desired stability in time, the liquid composition further comprises an effective amount of at least one pH- stabilizing agent, preferably in liquid phase, adapted to adjust the pH of the composition at a value such as to maintain the oxidizing agent substantially stable. Regarding this, the chemical nature of the pH-stabilizing agent is correlated to the nature of the oxidizing agent. Thus, for example, if the oxidizing agent in liquid phase is selected from the agents adapted to release a halogen when contacted with water, such as for example hypohalogenites of alkaline or earth-alkaline metals or precursors thereof, the liquid composition includes a pH-stabilizing agent capable of stabilizing the pH of the composition in a basic field and preferably in a pH field greater than 11. The amount of pH-stabilizing agent can be easily determined by the man skilled in the art as a function of the more or less accentuated basic reaction of the stabilizing agent once the latter is dissolved in water.

According to this first embodiment of the invention, the pH-stabilizing agent is therefore preferably selected from the group comprising the hydroxides of alkaline or earth-alkaline metals. In a preferred embodiment, the pH-stabilizing agent is a low-cost strong base, such as for example sodium hydroxide, whereas the amount thereof is from 0.3 to 2% by weight to the total weight of the liquid composition.

Preferably, the amount of sodium hydroxide is from 0.6 to 1.5% by weight and, still more preferably, equal to about 1% by weight to the total weight of the liquid composition.

If the oxidizing agent in liquid phase is selected from the agents adapted to release either oxygen when contacted with water, such as for example peroxy-compounds or precursors thereof, the liquid composition includes a pH-stabilizing agent capable of stabilizing the pH of the composition in acid field and preferably in a pH field of less than 4.

Also in this case, the amount of pH-stabilizing agent can be easily determined by the man skilled in the art as a function of the more or less accentuated acid reaction of the stabilizing agent once the latter is dissolved in water. According to this second embodiment of the invention, the pH-stabilizing agent is therefore preferably selected from the group comprising protic acids having a first ionization constant at 25°C of from 2 to 5.

Still more preferably, the pH-stabilizing agent is selected from the group comprising phosphoric acid, boric acid, formic acid, acetic acid, propionic acid, glycolic acid, glycoxylic acid, lactic acid, malonic acid, succinic acid, aleic acid, polyacrylic acid, citric acid, malic acid, and mixtures thereof. Additional preferred ingredients

According to the invention, it is furthermore preferable and advantageous that the liquid composition to be delivered contains further ingredients, conventional per se, in order to satisfy specific application requirements. Thus, for example, the liquid composition preferably comprises an effective amount of at least one sequestering agent for heavy metals capable of inhibiting the decomposing action exerted by the latter against the agent adapted to release halogen or oxygen. If the oxidizing agent in liquid phase is selected from the group comprising the agents adapted to release halogen, such as for example halogenites or precursors thereof, the sequestering agent for heavy metals is preferably selected from phosphonic acid or salts of alkaline or earth-alkaline metals thereof, suitably formulated to be stable in a basic environment and in the presence of the oxidizing agent. ^'

Alternatively, if the oxidizing agent in liquid phase is selected from the group comprising the agents adapted to release oxygen, such as peroxy-compounds or precursors thereof, the sequestering agent for heavy metals is preferably selected from phosphoric acid, also capable of being used a pH-stabilizing agent in an acid field, phenacetin, stannates of alkaline or earth-alkaline metals, acetanilide and oxyquinoline, also in this case suitably formulated to be stable in an acid environment and in the presence of oxidizing agent. Preferably, the amount of sequestering agent for heavy metals is from 0.05 to 5% by weight and, still more preferably, from 0.5 to 3% by weight to the total weight of the liquid composition.

Lastly, the liquid composition of the invention may further comprise an effective amount of at least one perfuming substance or of at least one dyestuff compatible with said oxidizing agent in liquid phase, i.e. capable of withstanding the oxidizing action thereof.

Preferably, the amount of perfuming substance or of dyestuff is from 0.001 to 3% by weight and can be easily determined in such a range by the man skilled in the art as a function of the specific features of such ingredients and/or of the specific application requirements of the liquid composition. The mechanical delivery system

According to the invention, it has been found that the liquid composition illustrated above is particularly suitable for use with a mechanical delivery system which can be hooked to the rim of a toilet bowl. In a particularly preferred embodiment, therefore, the system of the invention further comprises a supporting structure for the container provided with respective hooking means for supporting the container and the supporting structure inside the toilet bowl. According to the invention, it has moreover been found that the liquid composition illustrated above is particularly effective in allowing the desired technical effects (constant and regular delivery of dosed amounts of liquid composition, more than satisfactory cleaning/foaming and disinfecting/bleaching action at each flushing, suitable stability during use and during storage) to be achieved in the case in which the valve means of the mechanical delivery system comprise: bl) a valve body in which a metering chamber is defined between said outlet opening and a delivery opening for delivering the liquid composition from said metering chamber; and b2) a shutter slidably mounted in said metering chamber and displaceable by said opening device between said openings. Preferably, the opening device is provided with deflecting means adapted to direct part of the flushing water towards said delivery opening for the liquid composition and into the metering chamber.

Thanks to such a combination of features, it is advantageously possible to guarantee the delivery of dosed amounts of liquid composition at each flushing independently of the amount of substance present in the container, of the frequency of the flushing operations and, within certain limits, of the chemical -physical properties of the liquid composition. Surprisingly, in fact, the Applicant has observed that the pressure existing in the free space defined above the level of the liquid composition present inside the container closed in a fluid-tight manner can be effectively restored after each delivery of liquid by providing the opening device with the aforementioned deflecting means. These are capable, in fact, of directing part of the flushing water towards the delivery opening for the liquid composition so as to effectively take the latter away from the metering chamber of the valve means and to allow the entry of new air from the environment inside the container. In this way, the valve means of the invention advantageously allow a sufficient amount of air to be introduced into the system in an automatic and mechanically simple manner so as to prevent the formation of an undesired reduced pressure inside the container for storing the liquid composition, reduced pressure which would hinder the regular flow of the liquid composition towards the metering chamber. Preferably, the valve means of the mechanical delivery system comprise a valve body defined at a lower portion of a tubular element vertically extending in the supporting structure of the container and adapted to be longitudinally inserted for a portion of predetermined length inside the container.

In a preferred embodiment of the invention, the container of the liquid composition may be removably associated to the supporting structure. In such a way, it is advantageously possible to recharge the device by replacing only the container of the liquid composition with evident advantages of usefulness and cost reduction with respect to the case where it is necessary to replace the device as a whole. Preferably, moreover, the container of the liquid composition is made of a material having suitable features of transparency so as to allow the user to constantly detect the level of liquid contained therein and to provide for the recharge of the device when this is totally empty.

In order to protect the oxidizing agent against the degrading action of the light, in such a case at least one agent capable of suitably filtering light and of preventing, or at least reducing to the minimum, the photodegradation of the oxidizing agent is preferably added to the material of which the container of the composition is made.

In an alternative embodiment, the container of the liquid composition may be made of an opaque material, again in order to suitably filter the light.

Preferably, the container is provided in its lower part with an opening coaxially provided with a breakable closure membrane and is removably- associated to the supporting structure by engaging the tubular element into the opening of the container with interposition of the aforementioned membrane.

I such a way, during the storage of the container, the breakable membrane acts as a closure element of the container preventing the outflow of liquid composition, whereas, during use, the membrane acts as a gasket preventing leaks of the liquid composition at the contact area between the tubular element and the opening of the container once the latter is associated to its supporting structure.

Preferably, the opening of the container is formed at one end of a substantially cylindrical neck extending from the container and the tubular element may be longitudinally inserted up to a predetermined extent inside said neck. In this way, the engagement of the tubular element in the container opening is made more stable reducing to the minimum the risk of accidental displacements.

Preferably, the tubular element is cantilevered from the supporting structure and is provided with an essentially bevelled free end. Thanks to this feature, it is advantageously possible to easily break the closure membrane of the container when the container is associated to its supporting structure. Preferably, the valve means essentially consist of a ball valve including a substantially spherical shutter displaceable inside the metering chamber by the opening device between the upper and lower openings thereof, i.e. from a first position wherein it closes the delivering opening for the liquid composition to a second position wherein it opens said delivery opening and closes the outlet opening for the liquid composition, said outlet opening being formed in the container closed in a fluid-tight manner. In such a way, the upper and lower openings of the metering chamber constitute respective upper and lower valve seats against which the shutter abuts at the end of the upward or downward stroke thereof, as the case may be. Advantageously, the alternate displacement of the shutter inside the metering chamber between the upper and lower openings thereof allows to store in the aforesaid chamber dosed amounts of the liquid composition to be delivered and allows air to enter into the system reaching the fluid-tight container through the metering chamber. Preferably, the upper opening of the metering chamber is axially defined in a annular sealing ring associated to an inner wall of the tubular element in which the valve body is defined, said ring substantially abutting, during use, at the outlet opening for the liquid composition, said outlet opening being formed in the fluid-tight container. Thanks to this feature, when the shutter opens the lower delivery opening of the metering chamber and abuts against the annular sealing ring, the liquid composition previously stored in the metering chamber can be released and effectively washed away by the flushing water entering into the metering chamber, while preventing the flushing water from entering into the container and diluting the liquid contained therein. Preferably, the opening device of the valve means comprises a plate rotatably mounted below the supporting structure and provided with an actuator cantilevered therefrom and adapted to cooperate with the shutter of the valve means.

More preferably, the plate is rotatably mounted on the supporting structure by engagement of two pivoting arms downwardly extending from the aforementioned structure in respective slots which are laterally formed at opposite portions of the plate. In this way, the plate is bound to the supporting structure and acts on the valve means according to a first-class lever mechanism.

In a preferred embodiment of the invention, the deflecting means provided in the system for directing part of the flushing water towards the delivery opening for the liquid composition and into the metering chamber advantageously comprise the aforementioned plate of the opening device. In this way, it is advantageously possible to perform the double function of operating the shutter of the valve and of directing part of the flushing water towards the metering chamber to rinse the same and to wash away the liquid stored therein by means of a single element, i.e. by means of the plate. Furthermore, still more preferably, the deflecting means conveniently comprise a side wall, extending from a rear edge of the plate, which effectively contributes to direct the flushing water inside the metering chamber.

Preferably, the metering chamber is internally provided with means adapted to guide the displacement of the shutter in the metering chamber. Still more preferably, said means comprise a plurality of longitudinal ribs angularly spaced from each other and, preferably, spaced at a right angle from each other.

Advantageously, these guiding means allow to obtain a substantially rectilinear displacement of the spherical shutter in the metering chamber along a direction which is substantially perpendicular to the plane of the upper and lower openings of the metering chamber (upper and lower valve seats). In this way, the spherical shutter can be correctly positioned in abutment against the upper valve seat irrespective of any lateral push to which the shutter may be subjected, both due to the turbulence of the flushing water entering into and rinsing the metering chamber, and due to the radial movements of the opening device. Advantageously, the spherical shutter can be correctly positioned in abutment against the lower valve seat even when the flow of flushing water ends: in this case, the guiding means control the displacement of the spherical shutter in the lower valve seat in a suitable manner, while allowing fresh air to enter into the interspace defined between the shutter and the walls of the tubular element and from here to reach the free space defined in the container after having crossed the liquid composition stored here. Preferably, the delivery device further comprises a protection wall, cantilevered from the supporting structure and surrounding the plate. In such a way, it is advantageously possible to prevent that, as a consequence of any displacement of the delivery device, the plate may impinge against the inner wall of the toilet, damaging and/or blocking itself. Preferably, the delivering device of the invention further comprises stop means for the plate extending between the protection wall and the supporting structure. Such stop means, furthermore, advantageously allows both to direct the water flow onto the plate, thereby reducing the impact force thereof, and to stiffen the supporting structure.

Further aspects of the invention According to a further aspect thereof, the present invention relates to a liquid composition for cleaning and disinfecting a toilet bowl of the type described above and defined in claim 19 attached herein.

According to a further aspect thereof, the present invention also relates to a method for cleaning and disinfecting a toilet bowl as defined in claim 32 attached herein. Lastly, according to a further aspect thereof, the present invention relates to a kit of separate parts for combined use for cleaning and disinfecting a toilet bowl as defined in claim 33 attached herein.

Brief description of the figures

Further features and advantages of the present invention will become more readily apparent from the following detailed description of some preferred embodiments thereof, made with reference to the attached drawings for illustrative and not limiting purposes. In such drawings:

- figure 1 shows a perspective and exploded view of a preferred embodiment of the mechanical delivery system of the invention; - figure 2 shows a perspective view from below and in partial section of some details of the system of preceding figure 1;

- figure 3 shows a side view and in partial cross-section of the system of preceding figure 1 in a non-operative condition thereof;

- figure 4 shows a side view in partial cross-section of some details of the system of preceding figure 3 in an operative condition thereof. Detailed description of the preferred embodiments

With reference to figures 1-4, a system for delivering a liquid composition L into a toilet bowl 2 according to a preferred embodiment of the present invention is generally indicated with 1. The system 1 comprises a container 3 of the liquid composition L, said container 3 being closed in a substantially fluid-tight manner, a supporting structure 4, hooking means 5 of the container 3 and of the supporting structure 4 for suspending the same from the rim of the bowl 2, and means 6 for delivering dosed amounts of the liquid composition L. The container 3, the supporting structure 4, the hooking means 5 and the delivery means 6 are mass-produced at low costs by molding suitable plastics materials. The container 3, in the illustrated embodiment shaped as a spherical segment, is provided in its lower part with an opening 17, said opening 17 being coaxially provided with a breakable closure membrane 18 formed at an end 19 of a substantially cylindrical neck 20 extending from the container 3 itself.

The hooking means 5, which allow to releasably suspend the system 1 from the rim of the bowl 2, are structurally independent both from the container 3 and from the supporting structure 4, and comprise an arm 33 including an elastically deformable portion 9, which is substantially curvilinear and folded upon itself, adapted for engaging an outer portion 10 of the bowl 2 (see figure 3).

The curvilinear portion 9 is connected to a substantially rectilinear portion 11 which may be releasably associated to the supporting structure 4. The portion 11 comprises, cantilevered therefrom, three respectively upper 12a, intermediate 12b and lower 12c hooks, the function of which shall be described hereinbelow. In particular, the upper hook 12a allows to associate the arm 33 to the container 3 by means of a snap engagement in a corresponding seat 13a formed in the upper part of the container 3, whereas the remaining intermediate 12b and lower 12c hooks respectively allow to fix the arm 33 to the supporting structure 4 by engaging corresponding openings 13b and 13c formed therein. The means 6 for delivering the liquid composition L comprise valve means 7 for delivering dosed amounts of the composition, which valve means 7 in turn comprise a valve body 16 in which a metering chamber 24 is defined between a lower opening 8 for delivering the liquid composition L and an upper opening 44 in fluid communication with the fluid-tight container 3. The valve body 16 is defined at a lower portion of a tubular element 46 vertically extending in the supporting structure 4 and adapted to be longitudinally inserted for a portion of predetermined length inside the container 3.

More particularly, the tubular element 46 is cantilevered from the supporting structure 4 and is provided with an essentially bevelled free end 21 which is inserted for a portion of predetermined length inside the neck 20 of the container 3.

In particular, the container 3 is releasably associated to the supporting structure 4 by engaging the tubular element 16 in the opening 17 of the container 3 with interposition of the membrane 18 and of the upper hook 12a of the arm 33 in the seat 13a. In the illustrated embodiment, the valve means 7 essentially consist of a ball valve 22 including a substantially spherical shutter 23 preferably made of metallic material and having a weight of from 0.65 to 0.95 g.

The valve means 7 are provided with an opening device 14 operable at each flushing operation of water introduced into the bowl 2 and cooperating with said shutter 23. Preferably, the opening device 14 is provided with deflecting means, generally indicated with 45, which shall be described in greater detail hereinbelow, for directing part of the flushing water towards the delivery opening 8 for the liquid composition L and into the metering chamber 24.

The shutter 23 can be displaced in the metering chamber 24 by means of the aforementioned opening device 14, from a first position in which it closes the delivery opening 8 for the liquid composition L to a second position in which it opens the delivery opening 8.

More specifically, the shutter 23 is alternatively movable in the metering chamber 24 between the lower delivery opening 8 for the liquid composition L, at which a lower valve seat is defined, and the upper opening in fluid communication with the fluid-tight container 3, at which an upper valve seat at a predetermined distance from the delivery opening 8 is defined.

In a preferred embodiment, the upper valve seat is defined in an annular sealing ring 34 associated to an inner wall of the tubular element 46 and which prevents the flushing water from flowing through the upper opening 44 of the metering chamber 24 into the container 3 and from diluting the liquid composition L stored therein.

Conveniently, the sealing ring 34, during use, abuts substantially at the outlet opening 17 for the liquid composition L, said outlet opening 17 being formed in the fluid-tight container 3, in such a way that the upper opening 44 of the metering chamber 24 and the opening 17 are substantially coaxial with each other (figure 3). Preferably, the metering chamber 24 is internally provided with means 35 adapted to guide the displacement of the shutter 23 inside of the chamber 24. For example, such means 35 comprise a plurality of longitudinal ribs 36 acting as guiding means for the shutter 23 both when the latter moves upwards due to the action exerted by the opening device 14 and due to the action of the flushing water, and when it moves downwards towards the lower valve seat once the flow of flushing water has ended. In this embodiment, an interspace 37 is thus defined between the shutter 23 and the inner walls of the valve body 16 by the ribs 36. Very advantageously, such an interspace 37 allows both to store a predetermined amount of liquid composition L in the metering chamber 24, and allows the entry into the container 3 of an amount of air after the delivery of the liquid composition L, as shall be explained hereinbelow.

The opening device 14 of the valve means 7 comprises a plate 26 rotatably mounted on the supporting structure 4 and provided with a substantially conical actuator 27 cantilevered therefrom and adapted to cooperate with the valve means 7. More particularly, the plate 26 is rotatably mounted on the supporting structure 4 by means of a snap engagement of two pivoting arms 28a, 28b downwardly extending from the supporting structure 4, in corresponding slots 29a, 29b laterally formed at opposite portions of the plate 26.

In the illustrated embodiment, the deflecting means 45 for directing part of the flushing water towards the delivery opening 8 for the liquid composition L and into the metering chamber 24 comprise the plate 26.

In this case, the plate 26 comprises a side wall 47 extending from the rear edge 26a thereof and acting as a further element of the deflecting means 45 which advantageously allows to direct part of the flushing water in an effective manner towards the delivery opening 8 for the liquid composition L and into the metering chamber 24. For clarity, the terms "rear" and "front" shall be used in this description to indicate those parts of the plate 26 which are respectively distal from and proximal to the flow of flushing water (i.e. respectively distal from and proximal to the inner wall of the bowl

2).

In the illustrated embodiment, the plate 26 further comprises an edge 48 extending from the front peripheral end 26a thereof, which edge 48 acts as a further element of the deflecting means 45.

Advantageously, the edge 48 contributes to effectively direct part of the flushing water towards the delivery opening 8 for the liquid composition L and into the metering chamber 24. Advantageously, the device 1 further comprises a protection wall 30 which is cantilevered from the supporting structure 4, all around the plate 26, and stop means for the plate 26 essentially consisting of a baffle 31 extending between the protection wall

30 and the supporting structure 4.

Advantageously, the baffle 31 allows both to direct the water flow, thereby reducing the impact force of the water onto the plate 26, and to stiffen the supporting structure 4.

With reference to the system 1 described above, some non-limiting examples of liquid compositions L according to the invention which can be usefully used in combination with such a system 1 shall now be given.

Examples of formulations of the liquid composition L In the following examples, the various liquid compositions shall be defined indicating the parts by weight of each component, if not otherwise indicated.

EXAMPLE 1

A first liquid composition, illustrated in Table I, was prepared by cold mixing the various ingredients in a conventional manner until a limpid solution was obtained. The solution thus obtained was then poured into a container 3 of the delivery system 1.

The ingredients used were the following: cleaning agent: sodium laurylethersulfate (concentration of active ingredient equal to about 30%o) and coco dimethylamine oxide (INCI designation: Cocamine oxide). oxidizing agent: commercial sodium hypochlorite in 14/15%> v/v aqueous solution pH-stabilizing agent: sodium hydroxide in 30%> aqueous solution sequesterer of heavy metals: phosphonic acid in stable formulation at basic pH and in the presence of sodium hypochlorite.

EXAMPLE 2

A second liquid composition, illustrated in Table II, was prepared by cold mixing the various ingredients in the same way as in the preceding example 1 until a clear solution was obtained, which was then poured into a container 3 of the delivery system 1.

The ingredients used were the following: cleaning agent: sodium laurylethersulfate (concentration of active ingredient equal to about 30%)) and coco dimethylamine oxide (INCI designation: Cocamine oxide). oxidizing agent: commercial sodium hypochlorite in 14/15% v/v aqueous solution pH-stabilizing agent: sodium hydroxide in 30% aqueous solution

EXAMPLE 3

A third liquid composition, illustrated in Table III, was prepared by cold mixing the various ingredients in the same way as in the preceding example 1 until a limpid solution was obtained, which was then poured into a container 3 of the delivery system

1.

The ingredients used were the following: cleaning agent: sodium laurylethersulfate (concentration of active ingredient equal to about 30%)) and coco dimethylamine oxide (INCI designation: Cocamine oxide). oxidizing agent: commercial sodium hypochlorite in 14/15% v/v aqueous solution pH-stabilizing agent: sodium hydroxide in 30%> aqueous solution perfuming substance: of the type available on the market and resistant to the oxidizing action of sodium hypochlorite

EXAMPLE 4 A fourth liquid composition, illustrated in Table IV, was prepared by cold mixing the various ingredients in the same way as in the preceding example 1 until a clear solution was obtained, which was then poured into a container 3 of the delivery system 1.

The ingredients used were the following: cleaning agent: mixture of anionic and non-ionic surfactants known as COMPOUND®TDH (Cognis S.p.A. - Fino Momasco - Italy) and alkyldimethylamine oxide oxidizing agent: commercial sodium hypochlorite in 14/15% v/v aqueous solution pH-stabilizing agent: sodium hydroxide in 30% aqueous solution deionized water sequesterer of heavy metals: phosphonic acid in stable formulation at basic pH and in the presence of sodium hypochlorite.

EXAMPLE 5

A fifth liquid composition, illustrated in Table V, was prepared by cold mixing the various ingredients in the same way as in the preceding example 1 until a clear solution was obtained which was then poured into a container 3 of the delivery system 1.

The ingredients used were the following: cleaning agent: sodium laurylethersulfate (concentration of active ingredient equal to about 30%) and coco dimethylamine oxide (INCI designation: Cocamine oxide). oxidizing agent: commercial sodium hypochlorite in 14/15% v/v aqueous solution pH-stabilizing agent: sodium hydroxide in 30% aqueous solution deionized water.

Ways of delivering the liquid composition L

A method for delivering dosed amounts of a liquid composition L, for example of the liquid compositions described in examples 1-4 above, into a toilet bowl 2 essentially comprises the steps of associating a system 1 as described above to the bowl 2 and of ensuring that the flushing water operates the opening device 14 of the valve means 7 of the system 1.

More particularly, such a method can be carried out as follows.

Once the container 3 has been inserted onto the supporting structure 4, the system 1 can be suspended in known ways from the rim of the toilet bowl 2 so as to be ready for use according to a non-operative condition, shown in figure 3 with dotted and dashed lines. In particular, in such a non-operative condition, the shutter 23 of the ball valve 22 is pushed by its own weight and by the weight of the liquid composition L present in the container 3 into a first position in which it closes the lower delivery opening 8 of the metering chamber 24, whereas the plate 26 abuts against the baffle 31 in a position substantially perpendicular to the inner wall of the bowl 2.

In such a case, a dosed amount of the liquid composition L is stored in the metering chamber 24 and inside the interspace 37 since the latter is in fluid communication with the container 3 through the upper opening 44 of the metering chamber 24 positioned coaxially with respect to the outlet opening 17 for the liquid composition L, said outlet opening 17 being formed in the container 3.

When the water flushing inside the toilet bowl 2 is operated, part of the flushing water impinges upon the plate 26 onto which it is directed thanks to the presence of the baffle 31 , as indicated by arrows F in figure 4. As a result of the action exerted by the water on the plate 26, the latter is made to rotate in a clockwise direction indicated in figure 4, thus bringing the system 1 in an operative position wherein the actuator 27 causes a displacement of the shutter 23 from the delivery opening 8 towards the upper opening 44 of the metering chamber 24 which is consequently closed in a fluid-tight manner. At the same time, the plate 26 together with the front edge 48 and the rear wall 47 thereof - elements which form part of the deflecting means 45 - direct part of the flushing water - indicated by aiτow W in figure 4 - towards the delivery opening 8 for the liquid composition L and into the metering chamber 24.

In this way, part of the flushing water is able to enter in a turbulent manner into the metering chamber 24 and effectively wash away the amount of liquid composition L stored therein, which can consequently be rinsed in a substantially complete manner. At the same time, the shutter 23 is pushed into abutment against the upper opening 44 of the metering chamber 24 defined in the annular sealing ring 34 and interrupts the fluid communication between the metering chamber 24 and the container 3. In such a way, the shutter 23 effectively avoids the penetration of water inside of the latter and, therefore, avoiding any possible dilution of the liquid composition L. Thanks to the longitudinal ribs 36, the displacement of the shutter 23 takes place along a direction substantially perpendicular to the upper 44 and lower 8 openings (i.e. with respect to the upper and lower valve seats) irrespective of the actual direction of the pushing forces which are exerted against the shutter 23 by the flushing water entering into the metering chamber 24 and by the actuator 27.

When the pushing action of the flushing water ceases, the shutter 23, forced by its own weight and by the weight of the liquid composition L, if any, present inside the container 3, returns towards the lower valve seat, i.e. into a position in which it closes the delivery opening 8, while repositioning the plate 26 in abutment against the baffle 31.

Very advantageously, during the downward return stroke of the shutter 23, the residual water drips out from the metering chamber 24 and a dosed amount of fresh air taken from the outside can enter into the container 3 through the temporarily open passage defined by the interspace 37. Advantageously, this dosed amount of fresh air which enters into the container reaches the free space above the liquid composition L stored therein, so as to restore the pressure existing in the container 3 and to compensate for the decrease of the volume of the liquid composition L due to the previous delivery of a dosed amount thereof. During the downward return stroke 23, moreover, a further dosed amount of liquid composition L crosses the upper opening 44 and is stored in the metering chamber 24 and in the interspace 37, ready for a further delivery.

Repeated tests carried out by the Applicant with the system 1 and various formulations of the liquid composition L according to the invention, have shown that the system 1 allows both a constant and regular delivery of dosed amounts of the liquid composition adapted to give the desired cleaning/foaming and disinfecting/bleaching effects at each flushing, and a suitable stability during use and during storage of the liquid composition itself. Thanks to the special structure and operation of the mechanical delivery system of the invention, in fact, the liquid composition with cleaning/ foaming and disinfecting/bleaching action, having per se an intrinsic high instability in contact with the air and humidity of the external environment, is effectively isolated from the same by the valve means 7, which allow the delivery of the composition from the system 1 only at the moment in which the flushing water operates the opening.device 14. The operation of the valve means 7 and in particular of the opening device 14, moreover, turned out to be regular in all filling conditions of the container 3 and with all tested formulations of the liquid composition L.

From what is described and illustrated above, the advantages of the invention can be clearly seen. Among these advantages which there are: the possibility, for predetermined physical-chemical properties of the liquid composition L present in the container, of delivering dosed and constant amounts thereof independently of the amount of liquid composition L present in the container and of the frequency of flushing operations; a suitable stability during use and during storage of the liquid composition L; regularity and reliability of operation; low cost.

Clearly, a man skilled in the art may introduce changes and variants to the invention described hereinabove in order to satisfy specific and contingent application requirements, changes and variants which anyhow fall within the scope of protection as defined by the following claims.

TABLE I (Example 1)

TABLE II

(Example 2)

TABLE HI (Example 3)

TABLE IN

(Example 4)

TABLE V

(Example 5)

Claims

CLAIMS 1. System (1) for cleaning and disinfecting a toilet bowl (2) comprising: - a container (3) of a liquid composition (L), said container (3) being closed in a substantially fluid-tight manner; - valve means (7) cooperating with an outlet opening (17) for said liquid composition (L), said outlet opening (17) being formed in the container (3) for delivering dosed amounts of said liquid composition (L), said valve means (7) comprising an opening device (14) operable at each flushing operation by the water introduced into the bowl

(2); wherein said liquid composition (L) is stored in said container (3), has a viscosity at 20°C of from 25 to 500 mPa-s and comprises: a) from 15 to 70% by weight of an oxidizing agent selected from the agents adapted to release a halogen or oxygen when contacted with water, and mixtures thereof; b) from 1 to 25% by weight of a cleaning agent comprising at least one surfactant selected from the group comprising the anionic, cationic, non-ionic or amphoteric surfactants compatible with said oxidizing agent, said cleaning agent being such as to form, in combination with said oxidizing agent, a liquid composition (L) capable of mixing with the flushing water introduced into the toilet bowl (2) without forming hydration complexes or micelles during the flushing operations of said water; and c) an effective amount of at least one pH-stabilizing agent adapted to adjust the pH of the liquid composition (L) at a value such as to maintain said oxidizing agent substantially stable.

2. System (1) according to claim 1, wherein said oxidizing agent is selected from the group comprising: hypohalogenites of alkaline or alkaline-earth metals and precursors thereof, peroxy-compounds and precursors thereof.

3. System (1) according to claim 1, wherein said oxidizing agent is selected from the agents adapted to release a halogen and wherein said at least one pH-stabilizing agent is selected from the group comprising the hydroxides of alkaline or alkaline-earth metals.

4. System (1) according to claim 3, wherein said pH-stabilizing agent is sodium hydroxide and wherein said liquid composition (L) comprises from 0.3 to 2.0% by weight thereof.

5. System (1) according to claim 1, wherein said oxidizing agent is selected from the agents adapted to release oxygen and wherein said at least one pH-stabilizing agent is selected from the group comprising protic acids having a first ionization constant at 25°C of from 2 to 5.

6. System (1) according to claim 5, wherein said at least one pH-stabilizing agent is selected from the group comprising phosphoric acid, boric acid, formic acid, acetic acid, propionic acid, glycolic acid, glycoxylic acid, lactic acid, malonic acid, succinic acid, maleic acid, polyacrylic acid, citric acid, malic acid and mixtures thereof.

7. System (1) according to claim 1, wherein said at least one anionic, cationic, non-ionic or amphoteric surfactant is selected from the group comprising alkylsulfates of an alkaline or alkaline-earth metal comprising from 8 to 16 carbon atoms, linear or branched alkylethersulfates of an alkaline or alkaline-earth metal comprising from 8 to 16 carbon atoms and from 2 to 4 ethylene oxide (EO) units, linear or branched amine oxides comprising from 8 to 16 carbon atoms, linear or branched ethoxylate alcohols comprising from 12 to 16 carbon atoms and from 4 to 1 1 ethylene oxide (EO) units, and mixtures thereof.

8. System (1) according to claim 1, wherein said cleaning agent comprises at least one non-ionic or amphoteric surfactant and at least one anionic surfactant.

9. System (1) according to claim 8, wherein said at least one non-ionic or amphoteric surfactant is a linear or branched dimethyl-N-(alkyl)amine oxide comprising from 8 to 16 carbon atoms and wherein said at least one anionic surfactant is a linear or branched alkylethersulfate of an alkaline or earth-alkaline metal comprising from 8 to 16 carbon atoms and from 2 to 4 ethylene oxide (EO) units.

10. System (1) according to claim 8 or 9, wherein the weight ratio between said at least one non-ionic or amphoteric surfactant and said at least one anionic surfactant is from 1 to 25.

11. System (1) according to claim 1, wherein said liquid composition (L) further comprises an effective amount of at least one sequestering agent for heavy metals.

12. System (1) according to claim 1 1, wherein said at least one sequestering agent for heavy metals is selected from the group comprising phosphoric acid, phenacetin, stannates of alkaline or earth- alkaline metals, acetanilide, oxyquinoline, phosphonic acid or salts of alkaline or earth-alkaline metals thereof.

13. System (1) according to claim 1, wherein said liquid composition (L) further comprises an effective amount of at least one perfuming substance or of at least one dyestuff compatible with said oxidizing agent in liquid phase.

14. System (1) according to claim 1, further comprising a supporting structure (4) for the container (3) provided with respective hooking means (5) for supporting the container (3) and the supporting structure (4) inside the toilet bowl (2).

15. System (1) according to claim 1, wherein said valve means (7) comprise: bl) a valve body (16) in which a metering chamber (24) is defined between said outlet opening (17) for the liquid composition (L) and a delivery opening (8) for delivering the liquid composition (L) from said metering chamber (24); and b2) a shutter (23) slidably mounted in said metering chamber (24) and displaceable by said opening device (14) between said openings (8, 17).

16. System (1) according to claim 15, wherein said opening device (14) is provided with deflecting means (45) adapted to direct part of the flushing water towards said delivery opening (8) for the liquid composition (L) and into the metering chamber (24).

17. System (1) according to claim 14, wherein the container (3) of the liquid composition (L) is removably associated to the supporting structure (4).

18. System (1) according to claim 15, wherein the metering chamber (24) is internally provided with means (35) adapted to guide the displacement of said shutter (23) in the metering chamber (24).

19. Liquid composition (L) for cleaning and disinfecting a toilet bowl (2) having a viscosity at 20°C of from 25 to 500 mPa-s comprising: a) from 15 to 70% by weight of an oxidizing agent selected from the agents adapted to release a halogen or oxygen when contacted with water, and mixtures thereof; b) from 1 to 25% by weight of a cleaning agent comprising at least one surfactant selected from the group comprising the anionic, cationic, non-ionic or amphoteric surfactants compatible with said oxidizing agent, said cleaning agent being such as to form, in combination with said oxidizing agent, a liquid composition (L) capable of mixing with the flushing water introduced into the bowl (2) without forming hydration complexes or micelles during the flushing operations of said water; and c) an effective amount of at least one pH-stabilizing agent adapted to adjust the pH of the liquid composition (L) at a value such as to maintain said oxidizing agent substantially stable.

20. Liquid composition (L) according to claim 19, wherein said oxidizing agent is selected from the group comprising: hypohalogenites of alkaline or earth-alkaline metals and precursors thereof, peroxy-compounds and precursors thereof.

21. Liquid composition (L) according to claim 19, wherein said oxidizing agent is selected from the agents adapted to release a halogen and wherein said at least one pH- stabilizing agent is selected from the group comprising the hydroxides of alkaline or earth-alkaline metals.

22. Liquid composition (L) according to claim 21, wherein said pH-stabilizing agent is sodium hydroxide and wherein said liquid composition (L) comprises from 0.3 to 2.0% by weight thereof.

23. Liquid composition (L) according to claim 19, wherein said oxidizing agent is selected from the agents adapted to release oxygen and wherein said at least one pH- stabilizing agent is selected from the group comprising protic acids having a first ionization constant at 25°C of from 2 to 5.

24. Liquid composition (L) according to claim 23, wherein said at least one pH- stabilizing agent is selected from the group comprising phosphoric acid, boric acid, formic acid, acetic acid, propionic acid, glycolic acid, glycoxyhc acid, lactic acid, malonic acid, succinic acid, maleic acid, polyacrylic acid, citric acid, malic acid, and mixtures thereof.

25. Liquid composition (L) according to claim 19, wherein said at least one anionic, cationic, non-ionic or amphoteric surfactant is selected from the group comprising alkylsulfates of an alkaline or earth-alkaline metal comprising from 8 to 16 carbon atoms, linear or branched alkylethersulfates of an alkaline or earth-alkaline metal comprising from 8 to 16 carbon atoms and from 2 to 4 ethylene oxide (EO) units, linear or branched amine oxides comprising from 8 to 16 carbon atoms, linear or branched ethoxylate alcohols comprising from 12 to 16 carbon atoms and from 4 to 11 ethylene oxide (EO) units, and mixtures thereof.

26. Liquid composition (L) according to claim 19, wherein said cleaning agent comprises at least one non-ionic or amphoteric surfactant and at least one anionic surfactant.

27. Liquid composition (L) according to claim 26, wherein said at least one non-ionic or amphoteric surfactant is a linear or branched dimethyl-N-(alkyl)amine comprising from

8 to 16 carbon atoms and wherein said at least one anionic surfactant is a linear or branched alkylethersulfate of an alkaline or earth-alkaline metal comprising from 8 to 16 carbon atoms and from 2 to 4 ethylene oxide (EO) units.

28. Liquid composition (L) according to claim 26 or 27, wherein the weight ratio between said at least one non-ionic or amphoteric surfactant and said at least one anionic surfactant is from 1 to 25.

29. Liquid composition (L) according to claim 19, wherein said liquid composition (L) further comprises an effective amount of at least one sequestering agent for heavy metals.

30. Liquid composition (L) according to claim 29, wherein said at least one sequestering agent for heavy metals is selected from the group comprising phosphoric acid, phenacetin, stannates of alkaline or earth-alkaline metals, acetanilide, oxyquinoline, phosphonic acid or salts of alkaline or earth-alkaline metals thereof.

31. Liquid composition (L) according to claim 19, wherein said liquid composition (L) further composes an effective amount of at least one perfuming substance or of at least one dyestuff compatible with said oxidizing agent in liquid phase.

32. Method for cleaning and disinfecting a toilet bowl (2) comprising the steps of associating a system (1) according to any one of claims 1-18 to the bowl (2) and of ensuring that the flushing water operates the opening device (14) of said valve means (7) of the system (1).

33. Kit of separate parts for combined use for cleaning and disinfecting inside a toilet bowl (2), comprising: a) a container (3) closed in a substantially fluid-tight manner including a predetermined amount of the liquid composition (L) according to any one of claims 19-31 and having at least one outlet opening (17) for said liquid composition (L) coaxially provided with a breakable closure membrane (18); b) a supporting structure (4) for the container (3) comprising: bl) hooking means (5) for supporting the container (3) and the supporting structure (4) inside the toilet bowl (2), and b2) valve means (7) cooperating with said outlet opening (17) for said liquid composition (L) for delivering dosed amounts of said liquid composition (L), said valve means (7) comprising an opening device (14) operable at each flushing operation by the water introduced into the toilet bowl (2).