EP2935679A1

EP2935679A1 - Water-using domestic appliance with an interior surface which is to be cleaned and method for operating the same

Info

Publication number: EP2935679A1
Application number: EP13805916.7A
Authority: EP
Inventors: Andreas Bischof; Andreas Hanau; Hartmut Schaub
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2012-12-19
Filing date: 2013-12-17
Publication date: 2015-10-28
Also published as: DE102012223682A1; RU2015127470A; RU2622811C2; CN105026635A; CN105026635B; WO2014095876A1

Abstract

The invention relates to a water-using domestic appliance (1, 2) comprising a treatment container (3) for receiving objects (7) which are to be treated, at least one interior surface (10, 11, 33, 40, 41) and in particular a water supply line (8, 9), said interior surface (10, 11, 33, 40, 41) having a coating (17) with changeable polymers. The invention also relates to a method for operating said domestic appliance.

Description

Water-conducting household appliance with an inner surface to be cleaned and method for its operation

The invention relates to a water-conducting household appliance with an inner surface and a method for its operation. In particular, the invention relates to a water-conducting household appliance with a treatment container for receiving objects to be treated and at least one inner surface.

In water-conducting domestic appliances such as washing machines, washing dryers, dryers, in particular condensation dryers, or dishwashers, biofilms are frequently formed in the area of components with permanently moist surfaces. "Permanently moist surfaces" are in this case those which come into contact with water or aqueous liquids during proper operation of the household appliance.Particularly in aqueous systems, biofilms form on an interface, for example to a solid phase, and consist of a thin layer of mucus in which The microorganisms surround themselves with extracellular polymeric substances (EPS) to protect against external attacks and to improve their living conditions.The EPS together with hydrogels form hydrogels to form a mucilaginous matrix in which nutrients and other substances are dissolved ,

This often causes unpleasant odors in addition to dark deposits on the surfaces. Thus, biofilms that form, for example, in the Einspülschale and in areas of the tub of household appliances, create a hygienic, aesthetic and / or odor problem. Finally, the sanitation of storage water that is stored in some home appliances for re-use in later process steps can be of concern if the total bacterial count in the water, which directly correlates with the strength of the biofilm, becomes too great. Finally, it may also be due to the metabolism of microorganisms in the biofilm in addition to odor problems to discoloration and corrosion.

The formation of biofilms on surfaces of water-bearing household appliances should therefore be avoided as far as possible. In particular, already existing biofilms should be combated and if possible eliminated. For this it is known to surfaces in Household appliances biocide equip, for example, a Einspülschale a washing machine. Biocidally-treated surfaces, however, do not permanently prevent the formation of a biofilm because only the germs that are in direct contact with the surface that absorb the biocide die. Other germs that settle on the dead germ can often survive and multiply.

On the other hand, biocidal chemical substances acting on the outside of a biofilm generally kill only the upper germinal layers. The deeper layers are often not reached because they are protected by the EPS. In addition, chemical cleaners require use with a high concentration and with a long exposure time. Finally, biocides or chemicals or their reaction products are often harmful to the environment and / or harmful to health and can cause allergies, for example. Another problem is that a repeated use of biocides can lead to the formation of resistance of the microorganisms, whereby the control of microorganisms is further complicated.

Known thermal killing methods do not eliminate the biofilm itself, so that new germs can settle on the killed germs or the remaining biofilm. These often find an ideal nutrient situation, so that the re-colonization of microorganisms is often favored.

In addition, biological methods are known for avoiding and / or eliminating biofilms. DE 3841596 A1 describes a method for reducing the formation of slime and deposits in installations in which water circulates. In the process, non-sessile microorganisms which compete with biofilm-forming microorganisms for nutrient competition and thus reduce the formation of a biofilm are supplied to the circulating water.

EP 1 350 575 B1 describes a surface with switchable ultrahydrophobia and a process for the realization. In particular, the surface is a rough surface with a switchable intrinsic wettability, wherein in the context of the switching a reversible transition to a composite surface in the sense of the Cassie-Baxter theory takes place, comprising a substrate which is provided with a thin layer with switchable wettability. The intrinsic wettability is switched by temperature variation, pH Variation, electric fields or contact with selective solvents. The thin layer preferably consists of at least one hydrophilic and one hydrophobic component, which are enriched alternately on the surface by phase separation. For example, the thin film can be designed as a multi-component polymer brush and the phase separation can be realized by contact with selective solvents for the components thereof.

Brush-like polymers on surfaces with switchable properties are described by Petra Uhlmann et al. in "Scientific Journal of the Technical University of Dresden", Volume 56 (2007), No. 1-2, pages 47 to 51 described.

Switchable polymer surfactants are described in the Fraunhofer IAP Annual Report 2003 on pages 66 and 67.

Against this background, the object of the present invention was to provide a water-conducting domestic appliance in which the avoidance of training and the control of biofilms is improved. In particular, the removal of biofilms should be facilitated. The object of the invention was also to provide a method for operating such a household appliance. For the purposes of describing the present invention, the term "biofilm" is used herein to refer to a biofilm as such, as well as a non-biofilm-forming, more or less accumulated microorganism on an interior surface of the domestic water-conducting appliance.

The object underlying the invention is achieved by a water-conducting household appliance and a method for its operation according to the respective independent claims. Preferred embodiments of the invention are listed in the respective dependent claims. Preferred embodiments of the method correspond to preferred embodiments of the household appliance and vice versa, even if not separately pointed out here in each case.

The invention thus relates to a water-conducting household appliance with a treatment container for receiving objects to be treated and at least one inner surface, wherein the inner surface comprises a coating with a switchable polymer.

The term "coating" is here to be interpreted broadly, which covers more or less thin coatings of other materials, for example of metals or of other polymers.In addition, for example, a component of a household appliance, which has such an inner surface, have a switchable polymer or Thus, "coating with a switchable polymer" broadly means that at least one inner surface of the component has a coating with a switchable polymer. In this case, the coating can also consist in that on the inner surface, for example, can be located polymer chains which are more or less close to the inner surface, as long as at least one end of these polymer chains is anchored to the surface. Anchored can be a chemical or physical connection. As used herein, the term "switchable polymer" means that the polymer has at least two distinct states, which states are generally characterized by different internal or superficial structures that can be interposed between those in the water-bearing domestic appliance, that is, switching may occur Switching operation can be carried out, in which the polymer is transferred from a first state to a second state, in which a biofilm adheres poorly to the polymer compared to the first state Preferably, this switching process can be carried out reversibly, so that according to the invention preferably reversibly switchable polymers used In a preferred embodiment of the water-conducting domestic appliance, a structure of the switchable polymer can be switched by changing the external chemical and / or physical conditions e temperature, pH, ionic strength and / or pressure. In particular, the chemical conditions include the performance of a chemical reaction selected from the group consisting of a protonation-deprotonation reaction, a dissociation reaction, a rearrangement and an oxidation or reduction process. In the event that the switching operation is triggered by a change in temperature, such as a heating of the switchable polymer, for example, a switchable polymer having inner surface, such as a dispenser, be rinsed with sufficiently warm water as an example of a rinsing liquid or by switching sufficiently heated by embedded in the switchable polymer heating wires. In addition, both methods of switching the switchable polymer can be combined by a temperature change. Heating with a warm rinsing liquid, such as water or another aqueous rinsing liquid mixed with a cleaning agent, has the advantage that a biofilm which adheres poorly after a switching operation can be detached due to the mechanical action of the flowing rinsing liquid and, finally, even be washed away.

Preferably, a superficial structure of the switchable polymers and thus a property of the surface are switchable. The property may be, for example, the hydrophilicity of the inner surface, which generally differs by a more or less large wettability with an aqueous liquid and / or a more or less large adherence of microorganisms and thus biofilms, or size and / or roughness of the inner surface. In addition, in embodiments of the invention, in particular, the interior of the coating with switchable polymers can be designed such that the structure of the interior also changes during a switching operation. In this embodiment of the invention, it is also possible in particular to store biocidal substances in the coating, which can reach the surface more quickly and thus a biofilm after a switching operation. This would be an example of a controlled-release process by the inventive use of switchable polymers.

The coating can be relatively thin according to the invention. Preferably, the coating has a thickness of at most 5 μηη, more preferably of at most 2 μηη and most preferably of at most 1 μηη.

The water-conducting household appliance according to the invention is not particularly limited. All water-conducting household appliances, in which due to the presence of Water biofilms can form and in which therefore an avoidance, reduction and / or elimination of biofilms is desired, are suitable according to the invention, wherein the household appliance may in particular contain a water supply. Particularly preferred according to the invention is a dishwashing machine, a washing machine, a washer-dryer or a dryer, in particular a condensation dryer. A condensation dryer is a dryer in which a moist, warm process air from a drying chamber as a treatment chamber, which contains wet laundry, is removed by condensation in the moist warm process air water containing. The condensate is temporarily stored and / or discharged from the dryer, which is why a dryer is understood as a water-conducting household appliance.

The household appliance according to the invention comprises a treatment container for receiving objects to be treated, such as e.g. Clothes or dishes on. Often the treatment tank is therefore a drum. The term "treating" includes in particular a washing or drying of the objects to be treated.

In a particularly preferred embodiment, the household appliance according to the invention is a washing machine with a tub, a drum, a water inlet system and a lye drain system with a drain pump and a control device.

Preferably, a water-conducting household appliance is used which has a water reservoir for water used in the household appliance. In such a household appliance, a used aqueous liquid is stored for reuse as storage water and thus recycled. In a washing machine or a washer-dryer, for example, water from the last rinse, which is relatively clean, is suitable for this purpose. Such a water reservoir can be fed with water from various sources and depending on the exclusive or preferred source of water, for example, a condensate collection tank, a soft or hard water tank and / or a flushing water storage. In a dishwasher, a washing machine or a washer-dryer, the water reservoir is preferably a rinse water storage. In the rinse water storage usually used rinse water is cached, for example, in the to be reused following wash cycle. In the case of a dryer or washer-dryer, the water reservoir is preferably a condensate collecting container for the condensate produced during the drying of moist air, for example a condensate tray arranged below a heat exchanger. In addition, the water storage can also be a soft water tank or a hard water tank, for example, if a washing machine has a desalination device.

The water reservoirs mentioned are susceptible to the formation of biofilms, and thus the design of an inner surface with a coating of a switchable polymer is very advantageous. In particular, in the storage of rinse water to be reused in later process steps, so the sanitary requirements can be guaranteed.

In a further preferred embodiment, the water-conducting domestic appliance comprises a control device which is set up such that a switching process, for example, automatically or by a command of a user.

According to the invention, an inner surface in a water-conducting household appliance is not particularly limited and may be any inner surface located within such a household appliance, for example, surfaces of plastic, metal, rubber, etc.

Preferably, the surface is a permanently moist inner surface. In this case, a "permanently moist inner surface" is, in particular, a surface located in the interior of the household appliance, which comes into contact with water or an aqueous liquid during normal operation of the household appliance.

It is inventively preferred that the permanently moist inner surface comprises a Einspülschale, an inner tub wall, a water reservoir, a water supply line, a heat exchanger surface and / or a condensate tray. In this case, inner tub container wall preferably means the rear area of the drum mount, which tends to form biofilms in particular. A switching operation in the sense of the invention may take different lengths, wherein in the duration of the switching operation, as understood herein, in addition to the duration of the actual switching operation is switched by the between two states of the switchable polymer, in general, the time for maintenance of the second state is included.

The switchable polymers used are not restricted according to the invention, as long as a switching operation can be carried out in a water-conducting household appliance, which leads to the fact that the adhesion of a biofilm is deteriorated. The chemical nature of the switchable polymer will depend in particular on the type of triggering of the switching operation, ie in particular on the nature of the change in the external physical or chemical conditions.

For example, intrinsically conductive polymers such as unsubstituted or substituted polythiophenes, polypyrroles and / or polyvinylaromatics can be used as switchable polymers. Also particularly suitable are polymer surfactants, metal colloids, partially acylated polytrisacrylamides, poly (styrenesulfonate) -block-poly (acrylamide),

or so-called polymer brushes.

For example, a switchable polymer may be a polymer brush of at least two very different polymers in which one end is firmly bound to the material of a component of the household appliance. Depending on the external conditions, these different polymers can then accumulate alternately on the surface, so that the surface properties are each determined by one or the other polymer. You can switch between these states. Methods for preparing such polymers are described, for example, in Minko, S. (ed.): Responsive Polymer Materials. Arnes: Blackwell Publ., 2006.

In a preferred embodiment, therefore, the coating consists of polymer chains grafted onto the surface of at least two different polymers or comprising these. In general, these are incompatible, so that there is a segregation or a spatial separation of these polymer chains. Alternatively or in addition thereto, different polymers can be located in one surface, wherein the polymer chains do not substantially protrude from the surface.

The invention further relates to a method for operating a water-conducting domestic appliance with a water supply and a treatment container for receiving objects to be treated and at least one inner surface, wherein the inner surface comprises a coating with a switchable polymer, comprising the step

(a) changing the physical and / or chemical external conditions so that a state or a structure of the polymer is switched from a first state to a second state or a first to a second structure, which has a relation to the first structure deteriorated adhesion of a biofilm on the polymer.

Preferably, in the method of the invention, the switching between the first and second structures and back is performed sufficiently frequently and / or sufficiently long so that the surface properties of the switchable polymer are sufficiently changed by the change in physical and / or chemical external conditions to provide adhesion of biofilms. Moreover, it is preferred that the change in physical and / or chemical conditions is a change in temperature or pH.

The method according to the invention can be carried out at different times, for example as a method separate from a treatment method in a water-conducting domestic appliance. In a preferred embodiment of the method, however, a switching operation is carried out while a treatment program is carried out in the water-bearing household appliance with the objects to be treated in the storage container. For example, the inner tub wall is heated in the rear region of the storage, which tends to form biofilms, due to the movement of the drum. In particular, the heating during spin is very pronounced. Thus, especially during a spin step, a circuit of the switchable polymer are triggered. In a subsequent rinsing step, a less well-adherent biofilm can then be detached and removed together with rinsing liquid.

This opens e.g. in the case of a washing machine as a water-conducting domestic appliance according to the invention, the possibility that the method according to the invention can be carried out as a cleaning program both as part of a washing program, in particular in spin phases provided therein, as well as in the context of a separate cleaning program. A separate cleaning program is carried out in particular after completion of a wash program, so if existing laundry items are removed in a treatment tank.

In a preferred embodiment of a method according to the invention, therefore, a drum of a washing machine is operated at a preferably increased water level with high drum speeds. As a result, a biofilm present in particular in the rear tub area can be effectively eliminated.

In embodiments of the invention in which the domestic appliance is a dryer or a washer-dryer with a heat exchanger for moist, warm process air, in particular the heat exchanger is populated with a biofilm. On the other hand, during a drying process, the temperature of the heat exchanger can be appropriately raised, so that a switching operation is triggered and, as a result, the adhesion of a biofilm is degraded. Even if then by passing a refrigerant through the heat exchanger, the temperature drops again and thus restored by switching the original state, the adhesion of the biofilm may have deteriorated so that it can be washed away by means of the resulting condensate in the heat exchanger.

Another possibility for triggering a switching process is a change in the pH, for example from neutral to basic. This can be achieved, for example, by the action of an alkaline solution, for example a wash liquor, on the switchable polymer. This switching process can also be triggered during a wash program when, for example, an alkaline detergent is used in a wash program. In this case, in general, the contact time of the alkaline solution is so timed or sensor-controlled, that the alkalis penetrate a biofilm once formed and reach the switchable coating. A biofilm formed therein during the downtime of the washing machine as an example of a water-conducting household appliance according to the invention would then be removed when the washing program is carried out again.

Finally, the switching of the switchable polymer can also be effected by a change in the ionic strength in a solution or aqueous liquid in contact with the switchable polymer. The ionic strength of a solution can be increased, for example, by the addition of salts.

A change in the ionic strength can therefore be made particularly advantageous in such water-conducting domestic appliances, in which a solution with a high ionic strength can be easily provided. These are in particular dishwashers in which a regeneration solution of a water softener is used, and washing machines and washer-dryers with a device for desalting the water used therein. In such washing machines and washer-dryers, in addition to desalinated water, a solution with a high salt concentration usually also occurs. Again, it is generally useful to specify a minimum contact duration of the solution used for switching, so that a sufficient reduction of the adhesion of the biofilm can be ensured. In such an embodiment may be stored in the control device of the household appliance, a relationship between the minimum contact duration and size and type of biofilm, so that the minimum contact duration can be adjusted depending on a detected biofilm.

Depending on the nature of the inner surface or the method with which the switching operation is performed, it may be useful to effect the change of the external chemical and / or physical conditions by contacting an aqueous liquid, generally a solution, after one essentially with the inner surface is no longer moved ("static contact"). Alternatively, it is also possible to realize a dynamic contact in that a solution at the the inner surface to be switched past continuously or discontinuously.

A switching operation can also be effected by performing a chemical reaction on the inner surface. Depending on the oxidation or reduction potential of the switchable polymer, it is possible, for example, to carry out an oxidation or reduction process (also referred to collectively below as "redox reaction".) The change in the structure of the switchable polymer brought about by the switching process then consists in the fact that the oxidized / reduced and neutral form, in particular also those properties which result in a reduction of the adhesion of a biofilm Such a redox reaction can for example be brought into contact with the surface to be cleaned with an oxidizing agent such as ozone, gaseous or dissolved in water, or In this way, a biofilm can be detached by, on the one hand, a chemical attack on the biofilm as such happens and on the other hand, the oxidizing agent causes the switching of the switchable polymer.

A redox reaction can also be used advantageously in particular if electrically conductive polymers are present in the surface. Suitable electrically conductive polymers are derived, for example, from substituted or unsubstituted polythiophenes, polypyrenes, polyphenylenes and polyvinylaromatics. In these, a change in the oxidation state of the polymer can be effected by electrical or chemical means, wherein the different oxidation states generally differ in their structure and electrical conductivity. As a rule, in the case of electrically conductive polymers in the oxidized state, a chemical coupling system which is asconjugated as possible is present.

To effect such a redox reaction with electrically conductive polymers, for example, one of the aforementioned chemical oxidants such as ozone or hypochlorite can be used. Alternatively or in addition to this, the electrically conductive polymers can also be connected to a power supply, so that their structural and electrical properties can be selectively changed by changing an applied electrical voltage. In this way, a the electrically conductive polymer directly or indirectly, possibly via other polymers, adjacent biofilm be dissolved.

If an electrical conductivity at the surface is produced by a material whose structure does not change by applying an electrical voltage, for example by a metal or graphite being present on the surface, a biofilm can be oxidatively attacked by applying a sufficiently high oxidation potential. Moreover, by applying a sufficiently high oxidation potential, it is also possible to generate chemical species which may then be present as a layer and bring about a switching of a polymer which can be switched by redox reactions.

The method according to the invention can be initiated in various ways, in particular automatically or at the instigation of a user of the water-conducting household appliance. An automatic implementation of a method according to the invention can be carried out sensor-controlled or time-controlled.

In a preferred embodiment of a method according to the invention, therefore, the switching provided according to the invention takes place, preferably followed by a further rinsing with a rinsing agent, when a sensor indicates the presence of a biofilm on the inner surface.

Such a sensor may be, for example, an odor sensor or an optical sensor. For example, a method according to the invention can be initiated when a sensor signal reaches or exceeds a certain predetermined value for a smell or an optical property, such as scattering or absorption. The sensor may also be a turbidity sensor or a sensor for the detection of a refractive index, a surface tension or an electrical capacitance. Corresponding sensors can be located, for example, in the regions of the water-bearing household appliance that are particularly susceptible to biofilms. For carrying out the method according to the invention, the control device of the water-conducting domestic appliance is preferably set up in such a way that it can ascertain the presence or danger of the formation of a biofilm by means of the data obtained by the sensor. For this purpose, the control device in general signals from the sensor are received, which are then compared with stored in the control device corresponding data so that the presence of a biofilm or the risk of formation of a biofilm can be detected. Then, the inventively provided switching operation is then initiated at the switchable polymers. Alternatively or in addition thereto, a method according to the invention or the treatment provided therein can advantageously be carried out after a predetermined operating period of the household appliance has been reached or exceeded.

In a further embodiment, the inventive method is therefore initiated time-controlled. In this case, the switching operation of the polymer takes place at a time specified in the program. This will depend in particular on how the circuit of the polymer can be made. For example, the method may be triggered in a circuit due to an increase in temperature upon reaching a certain minimum temperature value ("switching temperature") in each wash or rinse performed with a sufficiently high temperature aqueous liquid If the ph value is changed, a switching process can be triggered by a sufficiently high change in the pH value, and a biofilm treatment step can be carried out automatically after a longer period of inactivity or frequent use of washing or rinsing cycles after certain time intervals.

Alternatively, it is according to the invention also preferred that the inventive method is initiated manually by a user of the water-conducting household appliance. Thus, for example, before a planned longer standstill of the household appliance, a method according to the invention can be carried out in order to eliminate a biofilm. Here, a switching process initiated by the user preferably takes place in combination with a corresponding rinsing process, in a washing machine advantageously for example by flushing from the dispensing dish, for example by flushing a rinsing liquid from a special chamber, or by release from a rinsing liquid container. In addition, the initiation of the treatment provided by the invention by the user can also be combined with corresponding sensors, for example by informing a user via optical or acoustic display means of the presence or danger of formation of a biofilm. This can, as described in connection with the sensor-controlled introduction, be determined via corresponding sensors and a correspondingly set program control. However, in this embodiment, the method according to the invention is not initiated automatically, but a suggestion is optionally displayed to the user, so that the user can manually initiate the step as desired. If the program controller determines the presence or the danger of formation of a biofilm on the basis of the signals of a sensor, this can preferably be displayed to the user. This is done for example by means of a display device by optical and / or acoustic signals. The method according to the invention can be carried out in the case of water-conducting domestic appliances, for example dishwashers, washing machines, washer-dryers or dryers, during an ordinary program sequence, in particular during a rinsing, washing and / or drying process. Then a separate "cleaning process" is unnecessary, however, the process according to the invention can also be carried out as a separate part program in a customary rinsing, washing and / or drying program or as a completely separate treatment program.

In particular, it is preferred that the treatment or, in the case of biofilm already present, the biofilm treatment step is carried out before and / or after longer periods of inactivity of the household appliance. During longer periods of inactivity, biofilms may form in particular, which according to the invention can be avoided and / or removed again. Particularly preferred is the implementation of the method according to the invention before longer downtime of the household appliance, since so already the formation of the biofilm can be avoided and unpleasant odors, corrosion, etc. do not arise.

In the method according to the invention, the loosened biofilm is preferably detached with the aid of a rinsing liquid and transported away from the surface, preferably disposed of. As the rinsing liquid, water as such or an aqueous liquid containing additives may be used. These additives may be, for example, detergents or oxidizing agents.

The rinsing liquid can be introduced in the water-conducting domestic appliance in different ways, generally depending on the type of domestic appliance and the biofilm-afflicted inner surface. Thus, the rinse liquid in a washing machine can travel the same way, i. in particular via the same lines, are introduced as a liquid used for the treatment of objects. In an alternative embodiment of the method according to the invention, the surface is sprayed with the rinsing liquid using a suitable spray device. In a preferred embodiment of the invention, the water-conducting domestic appliance therefore also comprises a spray device for the rinsing liquid. Finally, the household appliance according to the invention preferably comprises a rinsing liquid container for a rinsing liquid already discussed. Controlled by the control device of the household appliance, the rinsing liquid is then generally added in embodiments of the invention for carrying out the method according to the invention.

In this way, the microorganisms, and in particular biofilms whose adhesion has been degraded due to the switching of the switchable polymer, mechanically detached and removed. Such surfaces are found, for example, in the area of the dispenser tray and the tub of a washing machine or a washer-dryer. Since these regions are very susceptible to biofilm formation, it is particularly preferred if the reduction in adhesion is supplemented by such a subsequent mechanically acting rinse treatment.

Furthermore, it is preferred that the switching process provided according to the invention is coupled with other chemical or mechanical purification steps. In this case, a mechanical cleaning step may also mean brushing. For example, the use of an oxidizing agent such as ozone or hypochlorite, for example sodium hypochlorite, even if this is not used for a switching operation, too lead to an accelerated removal of a biofilm. Such a treatment step can take place before, simultaneously or after the circuit. Preferably, subsequent to the switchover and a chemical or mechanical cleaning step, a rinsing step with a rinsing liquid is carried out in order to remove a more or less dissolved biofilm or microorganisms from the inner surface and preferably from the water-conducting domestic appliance.

Household appliance according to the invention and method according to the invention have several advantages. In particular, they enable prevention, reduction and / or elimination of a biofilm on a surface in a water-conducting domestic appliance.

The adhesion of a biofilm is generally reduced in the practice of the invention so that it can be easily removed by, for example, rinsing with water or other rinse fluid and not merely killed, as in conventional methods. Moreover, it is possible to control a biofilm without producing harmful degradation products.

In embodiments of the invention, the method according to the invention can also reach areas in the household appliance which do not come into direct contact with a rinsing solution but have remained moist due to previous processes. Thus, a very thorough "cleaning" can be done.

By coating surfaces that can easily form biofilms with switchable polymers, the removal of formed biofilms can be improved and facilitated. For example, in a coating with amphiphilic, switchable polymers, the structure of the surface can be switched such that a transition from a hydrophobic to a hydrophilic surface and vice versa takes place. As a result, the adhesion of a biofilm can be deteriorated, as a result, in any case, the biofilm after switching lose its adhesive force. The no longer adherent biofilm can then be rinsed off, for example with a rinsing liquid such as water. Subsequently, the polymer can be switched back. This switching can advantageously also be carried out several times (toggling). In the following, the invention will be explained in more detail with reference to the exemplary embodiments shown in FIGS. 1 and 2.

Fig. 1 is a schematic representation of the presently relevant parts of a first embodiment of the inventive water-conducting household appliance, which is designed here as a washing machine.

Fig. 2 shows a vertical section through a water-conducting household appliance, which is designed according to a second embodiment of the invention as a tumble dryer, in which by means of an air-to-air heat exchanger, a heat recovery takes place.

The washing machine 1 shown in FIG. 1 has a tub 4 in which a drum 3 as a treatment container for items 7 as objects to be treated about a substantially horizontally disposed axis of rotation 35 of the drum 3 is rotatably mounted and can be operated by a drive motor 14 , The long arrow indicates a direction of rotation of the drum 3. Wäschemitnehmer 36 and scooping devices 37 on the inner surface of the drum shell cause an intensification of the flooding with wash liquor. 6

The washing machine 1 has a water supply line (also denoted as Laugenzulaufsystem), which is a water connection fitting for the domestic water network 8, an electrically controllable valve 9 and a supply line 10 to the tub 4, which is guided via a dispenser 1, from the incoming water detergent portions can transport into the tub 4 includes. In the supply line 10 is a siphon 21st

The dispenser 1 1 and a water storage 33 for recycled water as the inner surface according to the invention each comprise a coating 17 with a switchable polymer, which is switchable in the present case by a change in temperature as a change in the external physical conditions.

The first embodiment of the inventive water-conducting household appliance shown in FIG. 1 thus makes it possible to carry out the process according to the invention by virtue of the presence of switchable polymers. As a result of more or less long-lasting switching action, the adhesion of a biofilm on the inner surface is reduced. This process can be mechanically and / or chemically supported by applying a rinsing liquid, the use of a rinsing liquid also allows the removal of a detached biofilm. For this purpose, in Fig. 1, a rinsing liquid container 25 is connected via a water supply line 16 with an electrically controllable valve 9, which is a connection to the domestic water network 8. Thus, by introducing water, the rinsing liquid in the rinsing liquid container 25 can be diluted or replenished with water. In the case of the washing machine 1 of FIG. 1, the rinsing liquid container 25 is connected to the dispensing dish 1 1 via a first rinsing liquid feed line 20. In addition, a second rinsing liquid supply line 26 branches off from the rinsing liquid container 25 to the suds container 4 or to the drum 3, which enables the rinsing liquid to be introduced via a sleeve 24, which is only indicated in the view of FIG. 1, at a feed opening 23 of the drum 3.

Finally, the washing machine 1 of FIG. 1 has further possibilities for the use of a rinsing liquid. For this purpose, a supply line 18 branches off from the rinsing liquid container 25, which leads to a spray device 31 and to a water reservoir 33. In the supply line 18, a controllable closure device 28 is arranged, with which the supply of rinsing liquid can be controlled. Further closure devices may be present in a household appliance according to the invention. Via the spray device 31, which is arranged at a rear exit of the tub 4, the flushing liquid can be sprayed, for example, into the rear part of the tub 4, which is opposite a feed opening 23 not shown here. The inner tub wall and in particular its rear, the feed opening 23 facing away from the part is a permanently moist surface, which are particularly vulnerable to the formation of a biofilm.

Finally, a water storage 33 can be subsequently added to a switching operation with a rinsing liquid to the water reservoir 33 of harmful To clean microorganisms and possibly a biofilm and thus to realize a longer storage time of the storage water under hygienic conditions. In Fig. 1, the connection of the water reservoir 33 with the tub 4 is not shown in detail for reasons of clarity. For the acoustic and / or visual indication of the implementation of the method according to the invention, a display device 29 is located on the washing machine of the embodiment shown here.

In the first embodiment shown in FIG. 1, a sensor 5 is located in the dispenser 1 1. Sensor 5 is, for example, an odor sensor or an optical sensor, which can indicate the occurrence of accumulations of microorganisms or even a biofilm. The sensor 5 is connected to the control device 12 of the washing machine 1 and can cause the automatic execution of a method according to the invention when a predetermined sensor signal is reached or exceeded.

In addition, in the tub 4 of this embodiment, a heater 13, a pump 22 for pumping out aqueous liquid from the tub 4 and a sensor 15 for measuring the concentration of detergent and / or washing aid. These components as well as the valve 9, the drive motor 14, the controllable closure device 28 and the sensor 5 are connected to the control device 12, which can control the washing machine 1 in accordance with a schedule which is in accordance with a time program and / or the achievement of certain Measured values of parameters such as liquor level, liquor temperature, rotational speed of the drum, determination of the presence of microorganisms or a biofilm, concentration of detergent and / or washing aids, etc. may be bound within the washing machine 1.

2 shows a vertical section through a water-conducting household appliance, which according to a second embodiment of the invention is configured as a tumble dryer 2, in which heat is recovered by means of an air-air heat exchanger 40 a horizontal axis rotatable drum 3 for receiving not shown here, in particular to be dried, laundry items within which Wäschemitnehmer 36 for movement the garments are attached during a drum rotation. Process air is guided by means of a blower 19 via a heater 13 through the drum 3 in a supply air duct 38. In the supply air duct 38, room air is sucked in by the blower 19 from a supply air inlet 39. The heated air from the heater 13 is from the back, ie, passed from the dryer door 42 opposite side of the drum 3, through the perforated bottom of the drum 3, comes there with the laundry to be dried in contact and flows through the filling opening of the drum. 3 to a fluff grid 43 within the drying door 42 closing the filling opening. After passage through the drum 3, the process air flow in the drying door 42 is deflected downwards. The moist, warm process air enters an exhaust duct 33, in which an air-air heat exchanger 40 is located, which cools the warm, laden with moisture process air (here: exhaust air) and leads to condensation of the moisture contained in it to the exhaust outlet 27. The separated moisture is collected in a condensate pan 41, from where it can be removed, for example by pumping. For cooling, the dryer 2 via the supply air duct 38 supplied room air is used in the air-to-air heat exchanger 40. This supply air is heated by the warm, laden with moisture process air and then before entering the drum 3 by means of heating 13. In the second embodiment shown in FIG. 2, the condensate pan 41 and the air-air heat exchanger 40 as inner surface according to the invention comprise a coating 17 with a switchable by a temperature change polymer. In addition, a rinsing liquid container 25 is provided with which a loosened biofilm can be detached and transported away. For reasons of clarity, it is not specified here how the water supply to the rinsing liquid container 25 takes place. The rinsing liquid container 25 is connected via a third rinsing liquid supply line 30 with the air-air heat exchanger 40 and finally the condensate pan 41. A sensor 5 for a biofilm is present, whereby an inventive method can be initiated by the evaluation of a sensor signal.

The drum 3 is mounted in the embodiment shown in Fig. 2 at the rear bottom by means of a pivot bearing and front by means of a bearing plate 44, the drum 3 rests with a brim on a sliding strip 45 on the bearing plate 44 and so held at the front end. The control of the condensation dryer via a control device 12 which can be controlled by the user via an operating unit 34.

For acoustic and / or visual indication of the implementation of the method according to the invention, a display device 29 is located on the dryer.

LIST OF REFERENCE NUMBERS

1 washing machine

2 dryers

3 treatment tanks, drum

4 tubs

5 sensor (a) for biofilm, e.g. Odor sensor, optical sensor

6 wash liquor

7 pieces of laundry

8 domestic water network

9 electrically controllable valve

10 Supply line to the tub

1 1 dispenser tray

12 control device

13 heating

14 drive motor

15 Sensor for determining properties of an aqueous liquid

16 water supply line for rinsing liquid container

17 coating with switchable polymer

18 supply line for rinsing liquid, e.g. Water, the spray device and the water reservoir

19 blowers

20 First rinse fluid supply line to the dispenser tray

21 siphon

22 pump

23 feed opening

24 cuff

25 rinsing fluid container

26 Second rinsing fluid supply line for tub / laundry drum

27 process air output; exhaust air outlet

28 Adjustable closure device

29 display device

30 Third rinse fluid supply line for heat exchanger and condensate tray

31 Spray device for a rinsing liquid 32 rear outlet of the tub

33 water storage (for recycled water)

34 operating unit

35 axis of rotation

36 laundry pickup

37 scooping device

38 supply air duct

39 air intake

40 air-to-air heat exchangers

41 condensate tray

42 drying door

43 lattice grate

44 bearing plate

45 sliding strips

Claims

claims

1. Water-conducting household appliance (1, 2) with a treatment container (3) for receiving objects to be treated (7), at least one inner surface (10, 1 1, 33, 40, 41) and in particular a water supply line (8, 9) , characterized in that the inner surface comprises a coating (17) with a switchable polymer.

2. Household appliance (1, 2) according to claim 1, characterized in that a structure of the switchable polymer can be switched by changing the external chemical and / or physical conditions.

3. Household appliance (1, 2) according to claim 2, characterized in that the physical conditions include the temperature, the pH, the ionic strength and / or the pressure.

4. domestic appliance (1, 2) according to claim 2, characterized in that the chemical conditions, the implementation of a chemical reaction selected from the group consisting of a protonation-deprotonation reaction, a dissociation reaction, a rearrangement and an oxidation or reduction process, includes.

5. Household appliance (1, 2) according to one of claims 1 to 4, characterized in that a superficial structure and thus a property of the inner surface (10, 1 1, 33,40,41) is switchable.

6. Household appliance (1, 2) according to claim 5, characterized in that the property is the hydrophilicity of the inner surface (10.1 1, 33,40,41).

7. Household appliance (1, 2) according to one of claims 1 to 6, characterized in that the coating (17) has a thickness of at most 5 μηη.

8. Household appliance (1, 2) according to one of claims 1 to 7, characterized in that the coating (17) comprises a polymer from the group of metal colloids and / or partially acylated polytrisacrylamides.

9. Household appliance (1, 2) according to any one of claims 1 to 8, characterized in that the coating (17) consists of grafted onto the surface polymer chains of at least two different, incompatible polymers or comprises.

10. Household appliance (1, 2) according to one of claims 1 to 9, characterized in that the inner surface (10, 1 1, 33, 40, 41) is a permanently moist inner surface.

1 1. Household appliance (1, 2) according to claim 10, characterized in that the permanently moist inner surface, a Einspülschale (1 1), an inner tub wall, a water reservoir (33), a water supply line (10), a surface of a heat exchanger (40 ) and / or a condensate tray (41).

12. A method for operating a water-conducting household appliance (1, 2) with a treatment container (3) for receiving objects to be treated (7) and at least one inner surface (10, 1 1, 33,40,41) and in particular a water supply ( 8, 9), wherein the inner surface (10, 11, 33, 40, 41) comprises a coating (17) with a switchable polymer, comprising a step of physically and / or acting on the switchable polymers chemical external condition is changed, the

Changing the external condition causes switching of the polymer from a first to a second state, in which a biofilm adheres worse to the polymer than the first state.

13. The method according to claim 12, characterized in that the circuit between the first and the second state and back sufficiently frequently and / or sufficiently long is performed, so that the surface properties of the switchable polymer by the change of physical and / or chemical external conditions are changed sufficiently to reduce adhesion of biofilms.

A method according to claim 12 or 13, characterized in that the change in physical and / or chemical conditions consists in a change in temperature or pH.

Method according to one of claims 12 to 14, characterized in that a switching operation during a water-conducting household appliance (1, 2) with the objects to be treated (7) in the treatment container (3) performed treatment program is performed.