Patent Application
20170114489
The present invention generally relates to a washing machine having a decoloration device, as well as a method for washing textile substrates in said washing machine.
It is known that colorful textiles (textile substrates) can lose their color in the washing process. Depending on the wash temperature, the selected wash program, and the detergent used, there may be varying degrees of the intensity with which one or more dyes are washed out from the textile substrates. The dissolved dyes pass into the wash liquor—generally, washing suds—and are thereby brought into contact with other textile substrates, into which the dyes may pass. This leads to undesired discoloration, especially with bright-colored textile substrates, and may—as an example of the worst scenario—completely ruin an article of clothing.
Today, a large number of different dyes are used in the textile industry. These dyes vary greatly in the chemical structure thereof, properties thereof, and binding thereof to a textile. Thus, for example, distinctions may be made between direct dyes, reactive dyes, dispersion dyes, acid dyes, vat dyes, and others. Different fabric types—such as cotton, polyamide, or polyester—require different dye types, in order to have efficient and long-lasting coloring of these fabrics. This wide range of dyes used in the textile industry represents a major challenge for finding efficient measures against discoloration.
Various efforts have already been made, especially in the area of detergent compositions, to prevent the color loss process. Thus, today, color detergents are usually offset with dye transfer inhibitors, which are intended to prevent the transfer of dyes to other textile substrates. These additives have a disadvantage in mostly only being effective one or a small number of dyes, but not against a broader spectrum of dyes. Commercial dye transfer inhibitors thus exhibit, for example, a favorable effect against red direct dye, but no effect or only very little effect against dispersion dyes, acid dyes, or vat dyes. Precisely such a broad spectrum of colors does exist, however, in household color loads in the washing machine, because—for efficiency reasons—colors are generally only sorted in the broadest sense (darks and lights), but typically not by individual shades. Achieving an appropriate effectiveness against such a mixture of colors would require incorporating a large number of different dye transfer inhibitors into the detergent compositions. This, however, would have the undesired effects of raising both the complexity of the detergent formulation and the costs for the detergent.
U.S. Pat. No. 3,927,967 A discloses a method for removing stains from textile substrates, with which the textile substrates are subjected to a treatment with a detergent solution, a photoactivator, and oxygen, and are irradiated with visible light during this treatment process. However, such a method could not be used to treated dyed textile substrates, in particular, to eliminate the color loss process, because the treatment would tackle not only dyes dissolved into the wash liquor but also the dyes that are bonded to the textile substrates, thereby bleaching the textile substrates in an undesirable manner and causing the textile substrates to lose color.
WO 2009/067838 A2 discloses a method for cleaning the laundry with electrolyzed water, by means of oxidative radicals. For this purpose, a water tank is provided, in addition to the washing machine. The water contained in the tank is electrolyzed by an electrolysis unit, and thereby enriched with oxidative radicals that are highly reactive and thus have, inter alia, a cleaning and disinfecting action. The water treated in this manner is then supplied to the actual washing process. It is disadvantageous here that the textile substrates to be washed come into contact with the electrolyzed water during the wash process. This causes not only stains in the textile substrates but also the dyes that are bonded to the textile substrates to be attacked, which may lead to an undesired fading of the colors.
WO 01/71083 A discloses a washing machine that has a drum for receiving articles to be washed, wherein the drum has at least two rotatable drum sections and a drive, the drum comprising a plurality of different drum modes, including one mode in which the rotatable drum parts are driven so as to cause a relative rotation therebetween. A controller controls the device in order to perform a plurality of different wash programs, wherein each wash program has a corresponding drum mode.
WO 2010/094959 A1 relates to cleaning substrates by using a solvent-free cleaning system that requires the use of only small amounts of water. In particular, the document concerns cleaning textile fibers with the aid of such a system, and provides a device for use in relation thereto.
WO 2007/128962 A makes it possible to efficiently separate the substrate from polymer particles after completion of the cleaning process, and describes a design for use of two internal drums.
The present invention therefore addresses the problem of providing simple and low-cost measures that minimize the risk of discoloration during the wash cycle in a washing machine, while simultaneously protecting the textile substrates to be washed in the presence of water-insoluble solid particles.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
A washing machine (1) comprising a washing chamber (2) for receiving a wash liquor and textile substrates to be cleaned, a reservoir for a large number of water-insoluble solid particles, and a decoloration device (3) which has an inlet (4) for introducing wash liquor from the washing chamber (2) into the decoloration device (3) as well as an outlet (5) for discharging wash liquor from the decoloration device (3) into the washing chamber (2), and which, moreover, has at least one activator that is suitable for initiating, within the decoloration device (3), a process for forming free radicals in the wash liquor.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The following detailed description of the invention is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the invention.
The aforementioned problem is solved in a first embodiment by a washing machine (1) comprising a washing chamber (2) for receiving a wash liquor and textile substrates to be cleaned, a reservoir for a large number of water-insoluble solid particles, and a decoloration device (3) which has an inlet (4) for introducing wash liquor from the washing chamber (2) into the decoloration device (3) as well as an outlet (5) for discharging wash liquor from the decoloration device (3) into the washing chamber (2), and which moreover has at least one activator that is suitable for initiating, within the decoloration device (3), a process for forming free radicals in the wash liquor.
The washing machine in the sense of the present invention may fundamentally entail a conventional washing machine, for example, a cuboid washing machine having a capacity of about 1 to 20 kg, in particular, 4 to 9 kg of laundry, but may also entail an industrial-use washing machine having any capacity. The invention thus encompasses washing machine types of different designs and significantly larger capacities. The washing chamber entails the space through which wash liquor flows during a wash cycle. In a household washing machine, this is generally a washing drum and the immediately surrounding space.
It has been shown that the dyes passed into the wash liquor during the wash cycle can be decomposed by free radicals. Free radicals have at least one unpaired electron and are therefore extremely reactive, and thus usually short-lived (generally <1 second). They are able to react with the dyes dissolved in the wash liquor and decompose them. One example is the decomposition of the dye Acid Orange 7, which is broken down by the interaction with free radicals into colorless aromatic by-products that are then, in turn, converted by oxidation into aliphatic acids.
The washing machine according to the present invention makes use of this interaction behavior between free radicals and dyes. For this purpose, the washing machine comprises the decoloration device, into which the wash liquor enriched with dissolved dyes can be introduced from the washing chamber. The activator, which is suitable for initiating a process for forming free radicals in the wash liquor within the decoloration device, is arranged in the decoloration device. The free radicals thus formed attack and break down the dyes in the wash liquor. The wash liquor, having been treated in this manner, is then guided out from the decoloration device and into the washing chamber, and supplied to the further washing process in the washing machine. The proportion of dissolved dyes in the whole of the wash liquor located in the washing chamber is thereby significantly reduced, whereby the risk of textile discoloration is minimized.
The excellent effect of the free radicals against a variety of dyes has proven especially advantageous. This makes it possible to largely forgo detergent additives that are effective only against individual dyes, and possible to omit stringent sorting of the textile substrates to be washed according to the different shades prior to the wash.
The washing machine according to the present invention is advantageous in that exclusively the treatment of the wash liquor and/or also of the water-soluble solid particles may take place within the decoloration device; an undesired effect of the reactive free radicals on the textile substrates located in the washing chamber—in general, in a washing drum—and the dyed bonded therein is not possible or is largely eliminated. Both the inlet for introducing the wash liquor from the washing chamber into the decoloration device and the outlet for discharging the wash liquor into the washing chamber are designed for the purpose of making it impossible for textile substrates to reach the decoloration device. To accomplish this, the inlet and/or the outlet of the decoloration device may be fitted, for example, with suitable filters or grates that do not allow textile substrates to pass through but do allow the wash liquor and optionally the water-insoluble solid particles to pass through. The dimensions—in particular, the cross-sectional area—of the inlet and/or of the outlet may also be sized so as to render it impossible for textile substrates to enter into the decoloration device. According to the present invention, control of the inlet and outlet devices may also be provided, in order to control same in a time-dependent manner and thus bring in or out only the desired components. The length of the inlet and, in particular, the outlet of the decoloration unit is then sized such that, taking into account the mean flow rate of the wash liquor through the decoloration device and the mean lifespan of the free radicals, it can be assumed that practically no free radicals are present any longer in the treated wash liquor upon exiting from the decoloration device.
The wash liquor generally entails washing suds in which a detergent is dissolved in water. Depending on the requirements, other components may be mixed into these washing suds. In certain cases, pure water or other suitable liquids may also be put to use. Components of commercially available detergents are well known to a person skilled in the art.
In a preferred embodiment of the present invention, the activator comprises a UV radiation source, i.e., the process for forming free radicals in the decoloration device is initiated by UV radiation. In this embodiment variant, the wash liquor used is one that contains chemical additive components such as hydrogen peroxide (H2O2) or titanium dioxide (TiO2). The UV radiation emitted in the decoloration device by the radiation source activates the hydrogen peroxide or titanium dioxide contained in the wash liquor, producing—as short-lived products of this reaction—highly reactive hydroxyl radicals (OH radicals) that are capable of breaking down the dyes in the washing suds. In addition to the aforementioned hydrogen peroxide and titanium dioxide, it shall be readily understood that a large number of other chemical additives that can be activated by irradiation with UV under formation of free radicals are also suitable. The use of hydrogen peroxide is especially helpful, because hydrogen peroxide is already present as a bleaching agent in a large number of detergent compositions.
The concentration of hydrogen peroxide in the liquid portion of the wash liquor is preferably 0.1 to 50 mmol/L, particularly preferably 1 to 20 mmol/L. The liquid portion of the wash liquor is then understood to be the portion of the whole wash liquor—inclusive of the water-insoluble solid particles—that is obtained when the water-insoluble sold particles are separated out from the liquid portion by means of centrifuging 8 kg of the wash liquor, including the water-insoluble solid particles, for five minutes in a centrifuge having a horizontally-mounted cylindrical rotating body of 515-mm inner diameter and 370-mm inner depth, at 1400 rotations per minute.
Due to the isolated treatment of the washing suds in the decoloration device, which is accessible only for the washing suds and optionally the water-insoluble solid particles, but not for textile substrates, and due to the short lifespan of the free radicals, it is not possible for the UV radiation and/or the free radicals to act directly on the textile substrates and cause any damage thereto, for example, by decoloration.
A quartz lamp or a UV light-emitting diode may be used as the UV radiation source. However, other UV radiation sources are also conceivable, such as sunlight, gas discharge lamps, fluorescent lamps, LEDS, or lasers. Especially preferred UV radiation sources (6) are quartz lamps, sunlight, LEDs, or UV light-emitting diodes.
If a UV radiation source is provided as an activator, it is generally preferable for this source to be placed in the decoloration device in such a manner—and/or for the decoloration device to be designed in such a manner—that the washing chamber is not exposed to any direct UV radiation, more preferably, is not exposed to any UV radiation, so that dyes in the textile substrates, which may be present in the washing chamber, are not damaged. This can be done, for example, by having an aperture or a curve present at the entrance and exit in the direction of the washing chamber, forcing the wash liquor to flow through the aperture or around the curve. For example, the entrance and exit of the decoloration device may present as arranged in one direction, and thus not the direction of the washing chamber.
The preferred wavelength range of the emitted UV radiation is between 100 and 400 nm, particularly preferably between 250 and 400 nm. Initial tests indicate that there is a dependency between the wavelength of the emitted radiation and the type of decomposable dye. In addition to irradiation with a continuum, it shall be readily understood that it is also possible to adjust the UV radiation discontinuously, as well as with one or more discrete wavelengths.
According to another embodiment of the washing machine according to the present invention, beyond the pump generally provided in a washing machine, at least one additional pump may be provided, which pumps the wash liquor out from the washing chamber into the decoloration device and/or out therefrom. This enables a more efficient design of the decoloration process.
The use, intensity, and duration of the process for forming free radicals in the decoloration device are preferably adjustable. Thus, the use of the process may be coupled to the fulfillment of certain operating parameters, e.g., to a certain temperature of the wash liquor or to a certain phase of the wash cycle. For a temperature-dependent control, a temperature sensor may be provided, as an example, by which the temperature of the wash liquor can be ascertained. A purely time-based control may also be provided, where the process starts at a presettable time. Similarly, the duration of the process may be set so that the process stops as soon as the dye within the wash liquor falls below a certain quantity.
In wash cycles having a particularly low temperature, during which there is no fear of washing out of dyes into the wash liquor, the use of the process may also be stopped entirely. At high wash temperatures and during washing of textile substrates that especially readily lose color, the intensity and duration of the process can be increased accordingly.
The temperature of the wash liquor at which the washing machine according to the present invention can be operated may be between 10° C. and 100° C., preferably between 20° C. and 60° C.
The decoloration device may be fixedly incorporated into a housing of the washing machine, according to one embodiment of the present invention. Here, the voltage supply for the activator and optionally for the pump may be coupled to the voltage supply of the washing machine. The decoloration device may, for example, be attached underneath the drum, or on the inside of the door of the washing machine. For the intake of the wash liquor into the decoloration device and back out therefrom, corresponding lines may be provided in the washing machine, which lines can be connected to the inlet or outlet of the decoloration device. Thus, for example, the washing chamber may have a wash liquor outlet that can be connected to the inlet of the decoloration device. Correspondingly, the outlet of the decoloration device may be connectable to a wash liquor inlet of the washing chamber, so that the treated wash liquor can be guided out from the decoloration device back into the washing chamber. In another embodiment, however, the decoloration device may also be integrated into the pumping circuit that is generally present.
Alternatively, the decoloration device may also be configured as a separate, preferably battery-operated module. This module may, for example, be attached to the inner side of the door of the washing machine with the aid of a corresponding holder. The advantage of a module that can be introduced separately is that the module need only be used when necessary, and can thus be subjected to less wear. Moreover, a separate module can also be introduced after the fact, even in an already existing washing machine, or can be taken out from a defective washing machine and introduced into a new washing machine.
A special feature of UV radiation is that UV radiation also has a germ-killing effect in a wavelength range of 200 to 300 nm. This makes it possible to deactivate microorganisms such as bacteria, viruses, and protozoa. Thanks to this capability, UV radiation has been widely applied as an eco-friendly, chemical-free, and highly effective method for disinfecting water. Moreover, UV radiation is used to protect water from harmful microorganisms.
In contrast to chemical-based methods for disinfecting water, irradiation with UV is based on a physical process by which microorganisms are quickly and effectively deactivated. When subjected to the germicidal wavelengths of UV radiation, then bacteria, viruses, and protozoa lose the ability to reproduce and infect.
UV radiation has proven to be highly effective against pathogenic organisms including the causative agents of cholera, polio, typhoid, hepatitis, and other bacterial, viral, and parasitic diseases. Therefore, according to the present invention, UV radiation (alone or in combination with hydrogen peroxide) is used for UV oxidation, a process during which the number of microorganisms on the textile substrates and/or the water-insoluble solid particles and/or in the liquid phase of the wash liquor is reduced considerably.
Even photocatalytic water splitting is made possible according to the present invention by the use of short-wave UV radiation in the range of 250 to 300 nm, with use of suitable photocatalysts. These photocatalysts are added either to the detergent or to the water-insoluble solid particles, or may be composed partially or entirely thereof. It is also possible to introduce these photocatalysts so as to reside stationarily in the decoloration device. It is thus basically possible to forgo the use of quantities of hydrogen peroxide, due to the detergent or to hydrogen peroxide-generating components.
The present invention thus also discloses a module that: can be inserted into a washing machine; has a decoloration device having an inlet for introducing wash liquor into the decoloration device and an outlet for discharging the wash liquor out from the decoloration device; and that has at least one activator that is suitable for initiating, within the decoloration device, a process for forming free radicals in the wash liquor.
An essential feature of the washing machine according to the present invention is the presence of the decoloration device, which is integrated into the above device, as well as the aforementioned water-insoluble solid particles and a reservoir for the particles.
The washing machine according to the present invention typically has a hinged door in a housing, in order to make it possible to access the interior of the washing drum to provide an essentially closed system. Preferably, the door closes a window of the stationary, cylindrical drum, which is rotatably mounted within another drum, while the rotatably-mounted cylindrical drum is attached vertically within the housing. As a result, a front-loading device is preferred. Alternatively, the stationary cylindrical drum may be attached vertically within the housing, the access device then being located on the upper side of the device.
The washing machine is suitable for contacting the particles with the soiled substrate. Ideally, these particles are effectively circulated in order to promote effective cleaning.
According to the present invention, the washing machine comprises at least one reservoir, in particular, having a corresponding controller for the water-insoluble solid particles, the reservoir being located, for example, within the washing machine and suitable for controlling the flow of the particles within the washing machine, and containing the particles for regeneration. In another embodiment, the present invention relates also to a method for washing textile substrates in a washing machine by using the above-defined washing machine, comprising the steps of:
In addition, the invention shall be described in further detail through embodiments with reference to the accompanying drawings.
The functions of the decoloration device shall now be described in further detail, with reference to
A UV radiation source 6 is arranged within the decoloration device 3. The arrangement of the UV radiation source 6 within the decoloration device 3 is depicted only schematically in
If now a wash liquor (optionally containing hydrogen peroxide (H2O2)) in which dyes are dissolved is introduced through the inlet 4 into the decoloration device 3, then H2O2 molecules are activated by UV radiation emitted from the quartz lamp, producing short-lived, highly-reactive hydroxyl radicals (OH). These OH radicals attack and break down the dyes dissolved in the wash liquor. The wash liquor, having been thus decolored, is then guided through the outlet 5 back out from the decoloration device 3.
The term “decolored wash liquor” is intended to signify, according to the present invention, that the dye content of the wash liquor is significantly lower on leaving the decoloration device 3 than on entering the decoloration device 3. The absolute degree of decoloration is dependent on a variety of parameters, such as the original dye content in the wash liquor, the residence time of the wash liquor in the decoloration device 3, the radiation intensity of the UV lamp, and the like.
The washing machine 1, depicted in a simplified form in
The washing machine 1 according to the present invention, which comprises a decoloration device 3, and the method executed therewith to washing textile substrates thus represent an approach with the aid of which the risk of discoloration during the washing process in a washing machine can be minimized. In particular, the present invention is characterized in that a wide range of dyes can easily be broken down at the same time, without adverse effects on the textile substrates themselves caused by the color neutralization process. As a consequence of this reduced risk of discoloration, it is possible to largely forgo pre-sorting of textile substrates by colors prior to the wash, which represents significant time savings.
Another aspect of the present invention encompasses a method for cleaning a soiled textile substrate, wherein the method includes treating the wet textile substrate with a formulation that includes a large number of water-insoluble solid particles, wherein the particles are optionally reused after a regeneration with or without use of a detergent in further cleaning processes according to the method.
Optionally, the water-insoluble solid particles may be exposed to the UV radiation for the purpose of regeneration in the decoloration device during the wash cycle or in a separate step.
The substrate encompasses textile substrates, each optionally from a variety of materials, which may be either natural fibers such as cotton, or synthetic textile fibers such as Nylon 6.6 or a polyester.
The water-insoluble solid particles may be inorganic and/or organic in nature. The solid particles particularly preferably entail, for example, zeolites, clays, or ceramics. The particles may exhibit a certain level of hydrophilicity, in order to enable wetting with the wash liquor.
The organic water-insoluble solid particles may encompass any of a large number of different polymers. Particularly preferred are polyalkenes such as polyethylene and polypropylene, polyesters, and polyurethanes. However, the polymer particles are preferably made of polyamide, especially particles made of nylon, most preferably in the form of nylon chips. The polyamides are particularly effective for aqueous stain/dirt removal, whereas polyalkenes are particularly useful for removing oil-containing stains. Optionally, copolymers of the above polymeric materials may be used for the purposes of the present invention.
Different nylon homopolymers or copolymers may be used, including Nylon 6 and Nylon 6.6. Preferably, the polyamide encompasses Nylon 6.6 homopolymer having a mean molecular weight in the range of 5,000 to 30,000 daltons, preferably 10,000 to 20,000 daltons, most preferably 15,000 to 16,000 daltons.
The mean molar masses set forth here and hereinbelow, optionally, for other polymeric components refer to weight-average molar masses Mw, which can basically be determined by means of gel permeation chromatography with the aid of an RI detector, the measurement advantageously being performed against an external standard.
The water-insoluble solid particles or granulate, particles, or molded bodies are of such a shape and size as to enable favorable flowability and close contact with the textile substrate. Preferred shapes of the particles include spheres and cubes, but the preferred particle shape is cylindrical. The particles are preferably dimensioned so as to each have a mean weight in the range of 20 to 50 mg, preferably 30 to 40 mg. In the case of the most preferred cylindrically-shaped particles, the preferred mean particle diameter is 1.5 to 6.0 mm, particularly preferably 2.0 to 5.0 mm, most preferably 2.5 to 4.5 mm, whereas the length of the cylindrical particles is preferably in the range of 2.0 to 6.0 mm, particularly preferably 3.0 to 5.0 mm, and most preferably in the range of 4.0 mm.
Prior to the cleaning, the textile substrate is preferably moistened by wetting with water, in order to provide additional improvement for the wash liquor and thereby improve the transport properties within the system (pre-treatment). This facilitates a more efficient transfer of the detergent to the substrate and removal of dirt and stains from the substrate. Most conveniently, the substrate may be wetted by contact with tap water. Preferably, the wetting treatment is performed in order to achieve a substrate-to-water weight ratio of 1:0.1 to 1:5; the ratio more preferably lies between 1:0.2 and 1:2, wherein particularly favorable results are obtained with ratios such as 1:0.2, 1:1, and 1:2. However, in some cases, successful results may be achieved with the substrate-to-water ratio up to 1:50, although such ratios are not preferred in terms of the significant amounts of wastewater generated.
In the method according to this aspect of the present invention, which can be regarded as an interstitial method between cleaning and scouring, a weight ratio of textile substrate to water-insoluble solid particles is adjusted in the range of 1:1 to 1:30, in particular, 1:1.5 to 1:2.5, especially 1:2. Then, the proportion of water-insoluble solid particles is determined as the weight of the particles in the dry state, i.e., after 24 hours of storage at 21° C. and a relative humidity of 65%.
In addition, it has been shown that the water-insoluble solid particles can be regenerated, and that the particles can be satisfactorily used anew in the cleaning method, although a certain deterioration in performance is generally observed at three uses of the particles. When the particles are used anew, optimal results are obtained when the particles are coated anew prior to being reused with the detergent.
The water-insoluble solid particles can be regenerated in a known manner, such as, for example, is described in WO 2012/035342 A1. In the context of the present invention, the regeneration is performed by introducing the particles, optionally with commercially-available chemicals and/or the detergent, into the decoloration device, e.g., in a separate rinse cycle, optionally through addition of other cleaning agents that may also be aggressive in nature. The temperature of the regeneration step is independent of the wash temperature, if the textile substrate is taken out from the washing machine prior to the regeneration. Furthermore, the usual detergent raw materials may be used.
Another aspect of the present invention relates to the use of a detergent containing a precursor of free radicals, in particular, H2O2, for washing textile substrates with the use of a large number of water-insoluble solid particles.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 213 313.0 | Jul 2014 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2015/065622 | Jul 2015 | US |
| Child | 15401002 | US |
