Patent Publication Number: US-2006005584-A1

Title: Structural elements for washing machines, dryers or the like, doped or coated with germicidal material

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to a household appliance, particularly a clothes dryer or washing machine with an air-conducting and/or water-conducting system of individual structural elements, through which suds, a gas flow or the like can be conducted. This invention also relates to a washing machine with an air-conducting system of individual structural elements, within which air for drying can be conducted.  
      2. Discussion of Related Art  
      Today, washing machines and/or clothes dryers are particularly distinguished because they have particularly energy-saving washing and drying programs. This is especially achieved by lowering the process temperature. Thus washing temperatures of 30° C. to 40° C. are for example common which, although they show quite good washing results in connection with available laundry detergents, cannot prevent, especially at these low temperatures, the contamination of the laundry with bacteria, which are located particularly in certain structural elements, such as the metering device, in hoses or in filters, for example, and can greatly multiply there. These bacteria are the reason why the laundry smells musty during drying, if it is not dried in optimally ventilated basements or attic spaces. When drying the laundry outside, these bacteria are killed off to a large extent by the bleaching action of the UV radiation from the sun, which can have advantageous effects on the odor of the laundry. Also, laundry detergents with bleach added can positively affect this. However, the bleaching effect typically only starts at temperatures above 50 to 60° C., so that the required disinfecting effect does not occur, particularly with low-temperature washing processes.  
      Furthermore, washing machines are proposed for avoiding bacterial contamination of the laundry, wherein the circulating cleaning and rinsing fluid is subjected to a UV radiation source in an instantaneous waterheater, such as discussed in German Patent Reference DE 43 42 049. For bleaching and disinfecting the laundry in washing machines and dryers, German Patent Reference DE 211 00 63 teaches exposing the laundry to intensive ultraviolet radiation following the washing process or the drying process. It is disadvantageous in connection with such constructions that UV radiation results in increased energy requirements, and the replacement of the lights entails large expenses. As a rule, the use is connected with considerable structural changes of the total structure, which results in additional outlay for development.  
     SUMMARY OF THE INVENTION  
      It is one object of this invention to provide a washing machine or a clothes dryer of the type mentioned above but in which the disinfection of water-conducting or air-conducting elements is made possible with little cost.  
      In connection with a washing machine, this object can be achieved if the surface facing the air-conducting and/or water-conducting area of at least one of the structural elements is coated, at least partially, with a microbe-killing or bacteria-killing substance, and/or if the surface is doped with such a microbe-killing or bacteria-killing substance.  
      The coated or doped structural elements allow a strong check on the bacterial growth, or prevent it completely. With this it is also possible to check the contamination of the laundry, or to prevent it completely. The biocidal or anti-microbial effect can be maintained independently of additional energy sources such as electrical current, UV radiation, etc. This invention can also be advantageously integrated into existing structures and the geometric shape of the structural elements need not be modified at all, or only slightly. 
    
    
      For example, in connection with a washing machine, one or several of the following structural elements can be equipped in accordance with this invention: metering container for laundry detergent; a connector between the laundry detergent container and the washer tub; hoses; pumps for the suds; a housing of the pumps for the suds; a lint catcher; a washer tub; and/or door seals.  
      These are the structural elements which contact the wash water or the suds.  
      In connection with clothes dryers, this invention can be used, for example, for the design of the plastic drum and/or the air guidance, or a portion of the air-conducting system.  
      In accordance with one embodiment of this invention, the surface is at least partially covered with a coating, and the coating contains active anti-microbial or bacteriocidal agents.  
      The surface coating can be produced with a powdered lacquer coating by screen printing or a lacquering process.  
      In one possible embodiment of this invention, the structural element is at least partly of a plastic component, and an anti-microbially or biocidally acting substance, in particular a glass powder, is added to the material of this plastic component.  
      It is advantageous if the glass powder is at least in part of silicate, phosphate or borosilicate glass, doped with Ag, Cu and/or Zn. The glass compositions are particularly anti-microbial or biocidal.  
      The substance has already been appropriately admixed to the plastic material in its raw state, so that the latter can be formed into the desired structural element. All known methods, for example injection molding, pressing, extrusion, etc., can be used for forming.  
      It is also possible for the household appliance to be designed so that the structural element is formed at least in part by a silicate, a phosphate or a borosilicate glass, which is doped with Ag, Cu and/or Zn. The glass material forms a very smooth surface, which makes the adhesion of bacteria-generating substances difficult. Also, bacteria generation is prevented, or at least clearly reduced, because of the doping of the material.  
      In a further embodiment of this invention, the structural element contains silver-filled zeolite. Silver-filled zeolite releases the active AG +  ions relatively slowly. With this the biocidal effect of the structural elements is maintained for a long time.  
      Besides the employment of inorganic biocidal or anti-microbial active ingredients, the use of organic such ingredients is also possible. For example, the active ingredient Triclosan from Ciba Geigy can be used as the doping material for the plastic components.  
      A good bacteria-preventive effect is achieved if the layer applied to the surface, or the doped surface area, has a concentration of 0.5 to 10 weight-% of anti-microbial or bacteriocidal active ingredients.  
      With the present applications it is not necessary to observe the food supply and substance laws, and thus it is preferably possible to employ portions of more than 3 weight-%.  
      This invention can also be used, for example, for structural elements in vacuum cleaners, pressure cookers or the like, where bacterial contamination can occur during their use.  
      German Patent Reference 10 2004 031 633.3, the priority document corresponding to this invention, and its teachings are incorporated, by reference, into this Specification.