ITTO20111154A1 - WASHING MACHINE FOR WASHING MACHINES - Google Patents

Description

â € œWashing machine for washing machinesâ €,

TEXT OF THE DESCRIPTION

Field of invention

The present invention refers to washing machines and has been developed with particular reference to the theme of improving the exploitation of the washing agents used in such machines for carrying out the washing treatments.

Technological background

Washing agents used on washing machines commonly include five main groups of components, namely surfactants, fillers, buffers, softeners, oxidizing or bleaching agents, and enzymes. In general terms, a washing machine detergent can include the following active ingredients, grouped by components: surfactants (such as anionic surfactants, cationic surfactants, non-ionic surfactants), oxidizing agents (such as hydrogen peroxide, photo-oxidants, percarbonates, perborates) , enzymes (such as lipase, amylase, cellulase, protease), softening agents (such as soaps, zeolites, silicates, citrates), polymers (such as polycarbonates, polyethylene glycol, cellulose derivatives), other ingredients (such as buffers, perfumes, optical brighteners, suppressants of foam, chelating agents).

Regardless of the specific composition, the ingredients of the detergents are aimed at obtaining two main processes in aqueous solution:

i) the physical removal of dirt and stains from garments and their chemical modification by hydrolysis or oxidation (bleaching), which results in solubilization and / or discoloration of dirt and stains; And

ii) the protection of the fabrics through the use of polymers, the protection of the colors thanks to the color-lock technology or the inhibition of the transfer of dyes, the elimination of dirt and the ease of ironing.

Among the active components of detergents, oxidizing agents, such as sodium percarbonate and sodium perborate, are of particular importance. These whiteners essentially have the role of discoloring the stains, degrading the structure of the related colored substances. For example, percarbonate has a good whitening power as - when dissolved in water - it dissociates into sodium carbonate and hydrogen peroxide according to the reaction:

2Na2CO3 3H2O2 (aq) â † ’2Na2CO3 (aq) + 3H2O2 (aq)

However, its action is mainly carried out at temperatures above 40-50 ° C.

To overcome this problem, activators of oxidizing agents, such as TAED (Tetra Acetyl Ethylene Diamine), have been added to the detergent formulations of recent years. This molecule is an activator that allows the creation of new oxidizing molecules starting from hydrogen peroxide, that is the peracids. Peracetic acid, or more generally an acid belonging to the peracid family, which is formed as a reaction product, is an oxidizing agent much stronger than hydrogen peroxide and allows a good whitening action to be performed temperature around 25-35 ° C. The TAED, however, is a reagent that is depleted during the course of the reaction.

A possible way to improve the whitening action is to equip the washing machine with dedicated means, to add an additional whitener to the washing water, such as a perborate or a chemical carbonate in liquid or powder form, or to directly generate the peroxide. However, the use of an additional whitener imposes a certain complication in the realization of the machine and / or in its use by the user. The presence of any means to directly generate the peroxide (for example an electrochemical cell capable of dissociating water and air, to release hydrogen peroxide) certainly facilitates the use of the machine by the user, but complicates its realization and the management of operating programs.

Regardless of the construction and use aspects of the machine, it must be considered that the addition of bleached agents to the washing solution that already contains the normal commercial detergent can cause an excess of oxidizing substances, such as to cause the â € œdestructionâ € of others. active components of the detergent, for example enzymes, and also damage to the garments being treated.

Summary of the invention

In view of the foregoing, the present invention proposes to provide a laundry washing machine in which the exploitation of oxidizing components, possibly present in the washing detergents, is improved in a simple and economical way.

This and other objects, which will become clearer hereinafter, are achieved, according to the present invention, by a laundry washing machine having the characteristics indicated in claim 1. Particularly advantageous characteristics of the invention are indicated in the sub-claims. The claims form an integral part of the technical teaching provided herein in relation to the invention.

Brief description of the drawings

Further objects, characteristics and advantages of the present invention will become clear from the following detailed description, made with reference to the attached drawings, provided purely by way of non-limiting example, in which:

- figure 1 is a schematic section of a laundry washing machine according to the present invention;

- figure 2 is a partial and schematic perspective view of a first component of the machine of figure 1, and

- figure 3 is a perspective view in partial section of one second

component of the machine of figure 1.

Description of preferred embodiments

The reference to "an embodiment" within this description indicates that a particular configuration, structure, or feature described in relation to the embodiment is included in at least one embodiment. Therefore, the terms â € œin one embodimentâ € and the like, present in different parts within this description, are not necessarily all referring to the same embodiment. Furthermore, the particular configurations, structures or features can be combined in any suitable way in one or more embodiments. The references used below are for convenience only and do not define the scope of protection or the scope of the forms of implementation.

The idea behind the present invention is to equip the washing machine with a catalyst capable of carrying out an action similar to that of the TAED already normally present in commercial detergents, that is to transform oxidizing substances possibly present in the detergents in active oxygen, in the form of peracids, during the washing action. For this purpose, the catalyst in question is associated with at least one component which is in any case already normally provided on the machine, this component being chosen from among those which, during the operation of the machine itself, are in contact with the washing solution, ie water and detergent.

The activity of the catalyst thus allows a better whitening of the fabrics and oxidation of their stains, without thereby entailing significant constructive complications of the machine or its control logic, without complicating in any way the activity of the end user and without entailing any risk of damage to the garments being treated.

The catalyst in question acts synergistically with TAED or any other activators - such as NOBS (Nonanoyloxybenzenesulfonate), Nitriles or similar - possibly already present in the detergents used, allowing to increase the active oxygen in the solution, transforming perborates and percarbonates in a peracid, such as peracetic acid. Advantageously, the catalyst used in accordance with the invention allows to increase the formation of active oxygen from perborates and percarbonates even at low temperatures, particularly in the range of 20 ° -35 ° C.

In the preferred embodiment of the invention, the catalysts used in the machine according to the invention include transition metals (â € œdâ € group or â € œfâ € group of the periodic table of elements), transition metal oxides and salts insoluble transition metals, provided they are insoluble during washing conditions, i.e. in aqueous solutions with pH between 3 and 12, temperature below 75 ° C in the presence of enzymes, surfactants and all the various chemical agents present in the detergent formulations.

In a preferred embodiment of the invention, the transition metal in question is cerium, and preferably the catalyst is based on cerium oxide, most preferably based on platinated cerium oxide (0.5% platinum).

The principle on which the operation of the present invention is based is that of heterogeneous catalysis (where the term `` heterogeneous '' means that the catalyst has a different phase than the reactants that make up the main reaction) and assumes that the solution containing the € ™ washing agent is in contact with the catalyst. For this purpose, as will become clearer below, the catalyst can be associated with a stationary component of the machine according to the invention, or with its mobile component or belonging to a mobile part, it being understood that - during the treatment phases made with the aid of detergent - at least the part of the component that carries the catalyst is in contact with the water-detergent mixture.

Regardless of the type of component, in the preferred embodiment of the invention, the catalyst is located in a relative point of the machine which is not reached by the laundry items shaken during the treatment and contained in the drum of the machine. Practical tests carried out by the Applicant have made it possible to ascertain that this characteristic does not in any way reduce the activity of the catalyst aimed at transforming oxidizing substances such as perborates and percarbonates into peracids, allowing instead to safeguard the integrity of the catalyst itself over time. Thanks to this characteristic, the catalyst is not exposed to rubbing and friction with the garments being treated: on the one hand, therefore, it is not subject to wear and risks of removal and, on the other hand, the risk is avoided. that the catalyst can abrade the garments being treated.

In one embodiment, the component to which the catalyst is associated is formed at least in part with synthetic material, for example a thermoplastic material, and the catalyst covers at least this part. With this type of solution, the material can be deposited superficially to the synthetic component, even locally, in a very simple way, using any technique suitable for the purpose, for example selected from painting, PVD treatment (Plasma Vapor Deposition), CVD treatment (Chemical Vapor Deposition), PECVD treatment (Plasma Enhanced Chemical Vapor Deposition), cold-spray and the like.

In one embodiment, the catalyst can be integrated directly into a synthetic material which constitutes at least part of the component in question, at its surface. This solution is also very simple in construction and can be achieved, for example, by mixing the catalyst and the synthetic material during the molding phase of the component in question or of its part of interest. This implementation is particularly advantageous in the case of components obtained by molding plastic material, particularly thermoplastic material.

In one embodiment, the component with which the catalyst is associated includes at least a metal part and the catalyst itself superficially covers at least partially the aforesaid metal part. Even in such an implementation, the catalyst can be deposited superficially on the metal part, using any technique suitable for the purpose, for example selected from glazing, painting, PVD treatment (Plasma Vapor Deposition), CVD treatment (Chemical Vapor Deposition), PECVD treatment (Plasma Enhanced Chemical Vapor Deposition), cold-spray, electrophoresis and the like.

For a better understanding of the invention, some possible embodiments of the invention will now be described.

Figure 1 shows in schematic form a machine for washing laundry, indicated as a whole with 1. In the exemplified case, the machine 1 is a washing machine which includes a cabinet 2, inside which it is supported in a known way a tub 3. A drum 4 for laundry is rotatably mounted inside the tub 3, which can be rotated by means of an electric motor M. The drum 4 has a cylindrical wall to which elements for stirring the laundry are associated , or drivers, indicated with 5. The inside of the basket 4 is accessible to the user through an opening obtained in the cabinet 2 and closed, during the operation of the machine 1, by a door, all according to the known technique . The machine illustrated schematically is a front loading machine, but it will be appreciated that the invention is also applicable in the case of top loading machines.

Reference 6 indicates as a whole a dispenser of washing agents, of the type comprising a drawer-like container, for example divided into a plurality of compartments. The aforementioned drawer container is slidably housed in a hopper, having a lower outlet which is connected, via a tube 7, to the tank 3.

Alternatively, the dispenser of washing agents can be housed inside the door of the machine 1, according to a known technique.

8 indicates valve means, having an inlet intended for connection to a domestic clean water supply network 9. The dispenser 6 and the valve means 8 are designed to make a flow of water coming from the network 9 pass through the drawer container of the dispenser 6, according to the known technique, in order to remove the washing agent and add it to the tank. For example, if the drawer container is divided into a plurality of compartments, the water flow is made to pass selectively and in a controlled manner in one of the compartments of the aforementioned drawer, depending on the operating phase of the machine 1. The Water, after passing through the compartment of interest, exits from the aforementioned hopper container dragging the washing agent with it, and then reaches the tank 3 through the tube 7. As per the technique widely known in the sector, the means valves 8 may include a single solenoid valve and the dispenser 6 may be equipped with a movable nozzle, which can be controlled to selectively direct the flow admitted by the solenoid valve towards one of the aforementioned compartments; in another possible embodiment of the known type, the valve means can comprise a system of several solenoid valves in parallel.

The reference number 10 indicates a lower well of the tank 3, in correspondence with which means are mounted for heating the washing liquid, comprising a resistance 11. The well 10 has an outlet (visible in figure 2, reference 10a) in corresponding to which a discharge sleeve 12 is mounted, connected to the suction branch of a discharge pump 13, whose outlet branch is intended for connection to a sewer network 14. The machine 1 can also comprise, in a region inlet of the sleeve 12, a device aimed at reducing the waste of detergent, that is to avoid the passage in the discharge sleeve 12 of powdery detergent not yet dissolved in the water. Such a device, indicated schematically by 12a, can be of any known type, for example comprising a floating body, such as a hollow body or a bulkhead (see for example WO 87/02078).

Number 15 indicates as a whole the manual programming means of the machine 1, that is its user interface, comprising a control panel. The reference number 16 generally indicates a control unit, for example of the microcontroller type which comprises, or to which they are associated, non-volatile memory means. The operating or management programs are stored in the aforementioned memory means, which supervise the execution of the treatment cycles that can be executed by the machine and can be selected via the user interface 15. In these memory means, the instructions relating to the general functions of the machine 1. The machine 1 naturally also includes all the additional components necessary for its normal operation (level sensors, filters, door, safety devices, etc.), which are not represented and described here as they are not of immediate interest to purposes of understanding the present invention.

As previously mentioned, the catalyst used in the machine according to the invention - which here is supposed to comprise cerium oxide - can be associated with a stationary component of the machine 1, provided that this component - or at least its part bearing the catalyst - comes into contact with the water-detergent solution.

Figure 2 illustrates for this purpose the case of application of the catalyst to the tank 3, and more precisely in correspondence with the relative internal side, intended for contact with the washing liquid. In this case, the catalyst is preferably located in a lower region of the tank 3, that is the zone tended to be occupied by the washing bath. In the example shown, 3a indicates an insert that is partially embedded in a plastic material - for example filled polypropylene - of a body 3â € ™ which forms the peripheral wall of the tank 3. The upper surface of the insert 3a is directly exposed towards the inside of the tank 3 and at least on this surface of the insert the catalyst is deposited, for example through a selected technique including enamelling, painting, PVD treatment (Plasma Vapor Deposition), CVD treatment ( Chemical Vapor Deposition), PECVD treatment (Plasma Enhanced Chemical Vapor Deposition), cold-spray, electrophoresis and the like. The aforementioned insert 3a can be made of stainless steel, for example.

The catalyst can also be deposited directly on the plastic material constituting the body 3â € ™, for example in the same area that in figure 2 is occupied by the insert 3a. The deposited catalyst or an insert carrying the catalyst can also be located within the well 10. In the case of a tank 3 formed entirely in part of metallic material, for example steel, the catalyst can be deposited on the surface on this material.

Other stationary components of the machine 1 to which the catalyst can be associated with advantage belong to the means for loading the liquid into the tank, for example the hopper of the dispenser 6, in its part underneath the drawer container, and the tube 7. The catalyst can also be associated with components of the exhaust means, for example the part of the sleeve 12 which faces directly inside the tank, in correspondence with the hole 10a in figure 2. Another stationary component which can advantageously act as a substrate for the catalyst It is the heating resistance 11, on which the catalyst itself can be deposited using techniques similar to those used for the application of anti-limestone coatings, for example selected from enamelling, painting, PVD treatment (Plasma Vapor Deposition), treatment CVD (Chemical Vapor Deposition), PECVD treatment (Plasma Enhanced Chemical Vapor Depositio n), cold spray, electrophoresis and the like.

It will be appreciated that in the positioning examples given above, the washing liquid containing the detergent comes into contact at least temporarily with the catalyst, during the operation of the machine 1, in order to carry out its action. On the other hand, the catalyst does not come into contact with the laundry contained in drum 3.

On the other side, a possible mobile part of the machine to which the catalyst is associated is the basket 4, which, during its rotation, passes through the washing bath present on the bottom of the tank. As said, in the preferred embodiment of the invention, the catalyst is positioned so as to never come into contact with the laundry items being treated, and for this reason, the catalyst will preferably be placed on the outside of the drum. 4. Also in this case, the catalyst can be deposited on the surface on plastic or metal parts of the basket, or applied on inserts of the type previously indicated with 3a.

The catalyst can also be positioned inside the drum 3, but in a shielded position with respect to the laundry items. Possible advantageous embodiments in this sense are exemplified in figure 3.

Since the drivers 5 have a generally hollow section, the catalyst can be conveniently provided inside them, so as not to come into contact with the laundry. From this point of view, the catalyst can be deposited on an internal surface of the body 5â € ™ of the drivers, such as that indicated with 5a in figure 3, regardless of whether this body is metallic or - as more commonly happens - of plastic material. As in the case of other components mentioned above, the catalyst can also be integrated into the plastic material constituting the body 5â € ™ of the driver 5. Alternatively or in addition to the deposition on an internal surface of the body of the driver 5, at the inside its cavity 5c a metal sheet 5b can be housed, on the major surfaces of which the catalyst is deposited, as also exemplified in figure 3.

It will be appreciated that, during the rotation of the drum 4, the driver 5 will at least partially come into contact with the washing liquid present on the bottom of the tank, as normally occurs in any washing machine. The general structure of the driver 5 is of a generally known conception, and in this perspective it is coupled to the peripheral wall of the drum 3 in the absence of particular seals. In this way, part of the water-detergent mixture can penetrate into the cavity 5c of the driver and come into contact with the catalyst, which can therefore perform its function. In a preferred embodiment, the body of the driver 5 has a plurality of holes 5d, through which the mixture which penetrates into the cavity 5c can fall rain onto the laundry, during the rotation of the drum. In one embodiment, in order to facilitate the entry of water into the cavity 5c of the driver 5, the peripheral wall of the basket 3 can be provided with one or more openings in correspondence with the mounting area of the driver 5. Obviously all the drivers 5 of the machine can include the catalyst in question.

If the machine is equipped with an anti-waste detergent device, the catalyst can be deposited or integrated in the part of a relative component directly facing inside the tank 3, such as the aforementioned floating body (whether it is hollow or bulkhead type).

Previously, reference has been made to the possible direct integration of the catalyst into the plastic material which forms at least part of a component normally in contact with the water-detergent mixture. This measure is particularly advantageous in the case of thermoplastics, such as polypropylene. For this purpose it is sufficient to mix the chosen catalyst, in granular or powder form, to the granules of the material used for molding, to constitute a sort of additive. It has been found that, during the temperature melting of the thermoplastic material that occurs during the molding phase, the catalysts used - based as mentioned on transition metals - tend to migrate towards the surfaces of the metal mold used, to find themselves consequently in correspondence of the surface of the component thus formed. This surface will be characterized by a certain roughness, due to the presence of the catalyst particles, partially protruding from the molded plastic material, and therefore with the catalyst in a suitable position to be lapped by the water-detergent mixture.

It is also clear that, by exploiting widely known molding technologies, it is possible to make the components of interest with two different plastic materials, and therefore with a part containing the catalyst and a part that does not. Of course, depending on the case, the part containing the catalyst may be an external part of the component body (for example in the case of the basket 4) or an internal part (for example in the case of the tank 3).

It is clear that numerous other variants are possible for the person skilled in the art of grilling described as an example, without thereby departing from the scope of the invention as defined in the following claims.

The catalyst provided according to the invention can of course also be provided in parts of the hydraulic circuit of the machine other than those previously exemplified. For example, it should be noted that, in the case of machines equipped with a washing liquid recirculation circuit, the catalyst can be applied along a duct of this circuit. It is then clear that the catalyst can also be provided inside the drawer container of the dispenser 6, and particularly in its compartment or in its compartments which are dedicated to containing the usual commercial washing agents, containing as mentioned perorati and / or percarbonates.

The catalyst according to the invention can also be applied to a detergent container of the type intended to be placed inside the drum, directly between the laundry being treated (the so-called â € œdetergent-holder ballsâ €). In such a case, the catalyst will be applied inside the cavity of the aforesaid container, so as not to be reached by items of laundry.

Claims (14)

CLAIMS 1. A washing machine, comprising a washing tub (3), a laundry basket (4) mounted in said tub (3) and rotatable by motor means (M), loading means (6, 7, 8 ) to feed a liquid into said tank (3), a washing agent dispenser (6) to add at least one washing agent to the liquid, heating means (11) to heat the liquid, discharge means (10, 12, 13) to evacuate the liquid from the tank (3) and a control system (15, 16), characterized in that it includes a catalyst able to promote the transformation into peracids of oxidizing substances possibly present in the washing agent, the catalyst being associated with a component of the machine (1) which, during its operation, is in contact with the liquid containing the washing agent. The machine according to claim 1, wherein the catalyst comprises at least one of a transition metal, an oxide of a transition metal and an insoluble salt of a transition metal. The machine according to claim 1, wherein the transition metal is cerium. 4. The machine according to one of the preceding claims, wherein said component is a stationary component (7; 3; 10; 12). The machine according to one of claims 1 to 3, wherein said component is a movable component (4, 5, 12a), or belongs to a movable component (3). The machine according to claim 4 or claim 5, in which the catalyst is arranged in such a way that it does not come into contact with the laundry contained in the drum. 7. The machine according to claim 4, wherein said stationary component comprises at least one of: - the washing tank (3), the catalyst being associated with the inside of the tank (3), particularly in a lower region thereof; - a conduit (7) belonging to said loading means (6, 7, 8); - a sleeve (12) belonging to said discharge means (10-13); - a resistance (11) belonging to said heating means. 8. The machine according to claim 5, wherein said movable component comprises at least one of: - the laundry basket (4), the catalyst being associated with the outside of the basket (4); - a stirring member (5) mounted inside the laundry basket (4), the catalyst being associated with the stirring member (5); - a movable body (12a) forming part of an anti-waste detergent device associated with a discharge sleeve (12) of the tub (3). The machine according to any one of the preceding claims, in which said component has at least a part of synthetic material and the catalyst superficially covers at least partially the part of synthetic material. 10. The machine according to any one of the preceding claims, in which the said component has at least a part of synthetic material and the catalyst is integrated in the synthetic material at least in correspondence with its surface. The machine according to any one of the preceding claims, wherein said component (3; 5) includes at least a metal part (3a; 5b) and the catalyst at least partially covers the metal part (3a; 5b). The machine according to claims 6, 7 and 11, wherein the metal part (3a) comprises a tub insert (3). 13. The machine according to claims 6, 8 and 11, in which said stirring member (5) has an internal cavity (5c) and the metal part (5a) is inside said cavity (5c). The machine according to claim 6, wherein said component comprises a container for washing agents.