A METHOD FOR REMOVING A MATERIAL FROM THE SURFACE OF A PRODUCT

Abstract: A method for removing a material from the surface of a product, wherein said product is at least partially placed in a liquid medium, characterized in that a gas, in particular air, is extracted from said material. In a preferred embodiment, the gas is extracted by using a sub-atmospheric pressure, in particular a vacuum.

Description: A METHOD FOR REMOVING A MATERIAL FROM THE SURFACE OF A PRODUCT The invention relates to a method for removing a material from the surface of a product, wherein said product is at least partially placed in a liquid medium. The invention furthermore relates to a device for carrying out said method. A method and a device of this kind are generally known. With the known method, a soiled product is washed by immersing it in flowing water, whereby the dirt is washed off the product by the water. Possibly a cleaning agent is used thereby, for example a liquid detergent. One drawback of the known method is the fact that in practice it often takes a prolonged period of time and the use of large amounts of water and detergent to remove the material completely from the surface of the product, which is found to be inefficient and, taking into account the amounts of water and detergent that are used, unacceptable from an environmental point of view. Furthermore, relatively much energy is needed for causing the water to flow and to keep it flowing, whilst there is a danger that the soiled product will be damaged by the flowing water. Moreover, in many cases the product nevertheless appears to contain residual material on the surface thereof . The objective of the invention is to provide a method for removing a material which has adhered to the surface of a product, wherein the product is at least partially placed in a liquid medium, and in order to accomplish that objective, the invention is characterized in that a gas, in particular air, is extracted from the material. More in particular, said gas is extracted by using a sub-atmospheric pressure, in particular a vacuum. The invention is based on the insight that gas inclusions 2 are present in the material which is present on the surface of the product and also between said material and said surface, which gas inclusions "are released" when a sub-atmospheric pressure is applied. Generally, said gas is air. As a result of this, the material loses its adherence to the product surface, whereby the liquid medium has a soaking effect on the material and takes the place of the gas inclusions which are being released. Eventually, the material will crumble off completely from the product surface as the process progresses, or it can easily be removed afterwards. It is preferred to use a heated liquid medium in order for the process to take place more efficiently. In one preferred embodiment of a method according to the invention, an at least substantially stagnant liquid medium is used, in particular water. Preferably, the product is immersed in a container which is filled with said liquid medium, and a sub-atmospheric pressure, in particular a vacuum, is applied above the liquid medium. The sub-atmospheric pressure will thus cause the aforesaid air inclusions to be released and bubble up to the surface of the liquid medium. The air inclusions may be carried off via a filter that may be provided. As already said before, the extracted air inclusions cause the material, which frequently adheres firmly to the product surface, to break open. As a result of this, the material gradually loses its adherence to the product surface as the process progresses, and sinks to the bottom of the container in the form of detached parts, or it can be easily removed from the product surface afterwards. The latter takes place by squirting a liquid (water) onto the product for a short period, whereby the material is washed off the product . In another preferred embodiment of a method according to the invention, said sub-atmospheric pressure varies 3 between 0.01 and 17 bar, preferably between 0.1 bar and 0.2 bar (as an underpressure in comparison with the atmospheric pressure, which is generally approx. 1 bar) . The sub-atmospheric pressure is preferably controllable, in particular infinitely variably so. In another preferred embodiment of a method according to the invention, a cheese or a part thereof is selected as the product, from which a protective layer is removed. In order to protect cheeses against all kinds of diseases and plagues, they are generally enveloped in a protective layer of plastic material, which adheres firmly to the surface of the cheese. Presently, a container which is filled with a hydrogen peroxide solution (H 2 0 2 ) , in which the cheese is immersed, is used for removing said protective layer from the cheese. After the cheese has remained in the container for a number of hours, the adherence of the plastic layer to the cheese is largely lost. Not only has it become apparent in practice that a residence of about sixteen to eighteen hours in the hydrogen peroxide solution is required, but furthermore it is generally considered to be a drawback that all this requires a very large amount of water with hydrogen peroxide diluted therein. These drawbacks are overcome by subjecting the cheese to a process according to the invention. In another preferred embodiment of a method according to the invention, tubers, bulbs, stalk products or parts thereof, preferably potatoes, beets or bulbs, are selected as said product to be treated, from which dirt which is present thereon is removed. In another preferred embodiment of a method according to the invention, (perennial) plants or parts thereof, preferably peonies, are selected as the product, from which dirt which is present thereon is removed. 4 In another preferred embodiment of a method according to the invention, fibrous products, in particular clothing and the like, are selected as said product, from which fibrous products dirt which is present thereon is removed . In another preferred embodiment of a method according to the invention, crockery, cutlery and the like are selected as said product, from which dirt which is present thereon is removed. In another preferred embodiment of a method according to the invention, a facade is selected as the product, from which dirt which is present thereon, in particular graffiti, is removed. In another preferred embodiment of a method according to the invention, (frozen) fish, meat or vegetables are selected as said product, and the fish, the meat or the vegetables are cleared of ice. Presently, enormous quantities of flowing water, which may or may have a high temperature and which may or may not be provided with additives, are generally used for thawing the above products. This is not very efficient, whilst the thawing period is experienced as being (too) long. In another preferred embodiment of a method according to the invention, an archeological object is selected as the product, from which dirt which is present thereon is removed. It has become apparent that in particular heavy clay can be easily removed in a short period of time. In another preferred embodiment of a method according to the invention, a floor, in particular paving, is selected as the product, from which dirt such as chewing gum, sand, clay and/or mineral hydrocarbons, is removed. 5 As already said before, the invention also relates to a device for carrying out the method according to the invention, which device comprises a container, which is to be filled with a liquid medium, for the product to be placed therein, as well as means for generating a sub- atmospheric pressure, in particular a vacuum, above said liquid medium. In one preferred embodiment of a device according to the invention, the container comprises a supporting element for the product. In particular, means for supplying a gas, preferably air, to the liquid medium are provided. This makes it possible to prevent situations wherein for example the presence of ice, for example when fish are cleared of ice, causes the liquid medium (water) to freeze . In another preferred embodiment of a device according to the invention, the device is a washing machine or a dishwasher. In particular, it is a facade cleaner, more in particular a graffiti removing device. In another preferred embodiment, it is a floor (paving) cleaner. The invention will be explained in more detail hereafter by means of a few embodiments of preferred embodiments. 1. Treatment of cheese In order to remove a coating in the form of a protective layer of plastic material from a cheese, said cheese is immersed in a water-filled container, after which a vacuum, at least a sub- atmospheric pressure, is generated in the container, in the space above the water level. Gas inclusions are present between the actual cheese and the protective layer, whilst gas inclusions are furthermore present between sublayers of said 6 protective layer, which gas inclusions are released as a result of the presence of said sub-atmospheric pressure, and which bubble up to the surface. Water takes the place of the original gas inclusions, as a result of which the protective layer can subsequently be removed, that is, after about three hours, without any difficulty. Extensive tests have shown that this period can be shortened by heating the water, preferably to a temperature of about 50° C. Furthermore, the period of time within which the protective layer can be removed in accordance with the invention is reduced when the cheeses are placed in the container in such a manner that they do not touch each other. After said period, the protective layer can be simply removed by means of a spray-cleaning technique. 2. Treatment of frozen fish, meat or vegetables Fish, meat or vegetables in frozen condition are placed into a water-filled container, whereby the material is completely immersed. The container is then closed, after which a sub-atmospheric pressure, in particular a vacuum, is generated in the remaining space by means of a vacuum pump. As a result of this, air inclusions which are present in and around the ice enclosing the fish, meat or vegetables are extracted, which has a thawing effect. In the case of fish it has become apparent that frozen fish has completely thawed within three hours . 3. Treatment of textile, crockery, cutlery and the like As will be explained in more detail by means of a description of the figures, a washing machine and a 7 dishwasher, respectively, are used. The above products are placed into, respectively, the washing machine and the dishwasher, after which water is pumped into said machine for soaking the dirt which is present on the surface of said products. Then a sub-atmospheric pressure, preferably a vacuum, is generated in the container, with the aforesaid effect in accordance with the invention. The invention will be explained in more detail hereafter with reference to figures illustrated in a drawing of preferred embodiments of the invention, wherein Figure 1 is a schematic, perspective view of a device for removing a protective layer from cheeses; and Figures 2 - 5 are schematic, longitudinal vertical sections of devices for thawing fish, for cleaning a floor or a facade, for cleaning textile and for cleaning dishes, respectively. Figure 1 shows a container in the form of a steel vacuum tank 1, which is partially filled with hot water 2 having a temperature of 20 - 50° Celsius, preferably 25 - 40° Celsius. Cheeses which are provided with a usual protective layer (generally of plastic material) are placed separately or in a number of packages 3 on a conveyor belt 5, which is driven by a driving pulley 5. During the process according to the invention, the cheeses are present on stationary conveyor belt 4 in completely submerged condition, that is, below the water line 6. It is preferable to place the cheesed onto conveyor belt 4 before cleaning takes place, when the vacuum tank 1 is not filled with hot water yet, that it, when it is still empty, in such a manner that the cheeses do not touch each other, to which end said 8 conveyor belt 4 is moved a small distance each time to make space available for cheeses to be placed thereon at the end of conveyor belt 4 that faces towards the transverse opening of vacuum tank 1. Vacuum tank 1 is then closed and filled with hot water, until the water reaches line 6. Then the space 7 within vacuum tank 1 above water line 6 is evacuated, as a result of which, as already indicated above, gas inclusions which are present between sublayers of the protective layer enclosing the cheeses and also between said protective layer and the cheese surface bubble to the surface. As a result of this, the protective layer has come "loose" from the cheese surface within a few hours, to such a degree that it can subsequently be removed therefrom without any difficulty, for example by spraying a jet of water (lightly) onto the cheeses. After the evacuation phase, air is admitted into space 7, water 2 is pumped out, vacuum tank 1 is opened and the cheeses can be lifted off conveyor belt 4 at the end thereof by moving the conveyor belt in little steps, after which the protective layer can be removed completely by means of a spray cleaning technique. If products are to be thawed, as will be discussed in more detail with reference to Figure 2, vacuum tank 1 will furthermore comprise an air inlet 8 with a perforated air baffle 9 to prevent the water from freezing. Figure 2 relates to the thawing of frozen fish products 10, which are placed in vacuum tank 1, whereby the ice usually causes the fish products to adhere to each other. Those parts of vacuum tank 1 that correspond with parts which are shown in Figure 1 are indicated by the same numerals. After the frozen fish parts 10 have been placed onto perforated air baffle 9 in the vacuum tank 1, which is not filled with water at that stage, vacuum tank 1 is closed and partially filled with water 2, that is, up to line 6, whereby the fish parts 10 are 9 completely submerged. The filling of the tank with water 2 takes place by means of a liquid valve 11, which, when open, allows water 2 to flow into the vacuum tank 1 via jets 12. In the closed condition of liquid valve 11, the water flow to jets 12 is shut off. Once the filling stage has been completed, space 7 above water line 6 in vacuum tank 1 is evacuated, to which end a gas pump/valve device 13 is provided. This will cause the ice enclosing the fish parts 10, in which air inclusions are present, to thaw in a short period of time, without causing damage to the fish, in particular as far as its structure is concerned, which can be ascribed to the vacuum-induced escape in upward direction of gas inclusions in an around the ice. In order to prevent the water 2 from freezing during thawing, due to the presence of the remaining ice, an air inlet 8 is provided, which causes air bubbles to rise through perforated air baffle 9, thus imparting sufficient "dynamism" to the ice to prevent it from freezing. Air inlet 8 is actuated by a gas valve 19, which, when open, allows an air flow to air baffle 9, and which, when closed, shuts off the air flow to said air baffle. After thawing, space 7 is filled with air again and water 2 is pumped out through a liquid pump/valve device 15, after which the thawed fish parts 10 can be removed one by one from vacuum tank 1 for further processing. Figure 3 refers to a, preferably portable, facade cleaner for removing in particular graffiti from facades and the like, and to a floor (paving) cleaner for cleaning floors and the like, whereby the removal of chewing gum, tar etc. may be considered. Parts which correspond with parts which are shown in Figures 1 and 2, are indicated by the same numerals. In this figure, a surface (facade, floor) is indicated at 16, whilst numeral 17 indicates a seal between the surface 16 and the cleaner. The material to be removed from surface 16 10 is indicated at 18. Since the operation of cleaner 1 corresponds with that of vacuum tank 1 as shown in Figures 1 and 2, this operation will not be discussed now. Figure 4 shows a drum-type washing machine 19 comprising a housing 20, which is provided with a door 21. A vat 22 is present inside housing 20, in which a perforated rotary drum 23 is disposed. The inside of rotary drum 23 forms a washing space 24. Vat 22 and rotary drum 23 can contain water to a level which is sufficiently high for immersing the laundry which is present in drum 23. Rotary drum 23 is mounted on a rotary shaft 25, which is journalled in bearings 26 and which is provided with a pulley 27, by means of which said shaft can be driven. Rotary washer 19 furthermore comprises all the usual components, insofar as said components are not described as being different hereafter. Sprayers 28 are mounted inside the drum 23, which sprayers correspond with the sprayers 12 of Figures 2 and 3. Sprayers 28 are connected to a water pipe 29 via a pump (not shown) , whilst furthermore a liquid pump/valve device 30 is provided for pumping the washing water out of vat 22 after washing. The function of device 30 corresponds with that of device 15 of Figures 2 and 3. In order to enhance the washing effect, rotary washer 19 comprises a gas pump/valve device 31 for evacuating the space present above the water level in drum 23. As a result of this, the laundry which is present in drum 23 will be cleaned optimally, because gas inclusions in and around the dirt which is present on the laundry will bubble up and cause said dirt to break open. The result of this is that the dirty washing water can be pumped out by means of liquid pump/valve device 30, while clean laundry remains in drum 23. Figure 5 shows a dishwasher 32, which comprises a 11 washing space 35 and a door 34, thus forming a washing space 35. Objects which are to be cleaned are placed in washing space 35 in a known manner. Washing machine 32 comprises the usual components for such a machine, insofar as said components are not described as being different hereafter. Sprayers 36 are mounted at the top of washing space 35, which sprayers correspond with the sprayers 12 and 28 of Figures 2, 3 and 4. Said sprayers 36 are connected via a water pipe 37, in a manner already indicated above, to a water supply source. At the bottom of the washing space 35, a liquid pump/valve device 38 is provided, which corresponds as regards its function with devices 15, 30 as shown in Figures 2, 3 and 4. Device 38 contains a screen (not shown) . In accordance with the method of the invention, the dishes to be cleaned are entirely immersed in washing space 35 by means of sprayers 36, after which a gas pump/valve device 39, which corresponds as regards its function and operation with device 13, 31 of Figures 2, 3 and 4, evacuates the space in washing space 35 above the water level . Gas inclusions in the dirt on the dishes and between the dirt and the dishes will bubble up, thus breaking open the dirt on the dishes, wherein loose dirt particles sink to the bottom, form where they are pumped out together with the water by means of the liquid pump/valve device 38. Perfectly cleaned dishes will remain in washing space 35. It stands to reason that said dishes cannot be removed one by one from the washing space before the vacuum has been released and the dirty washing water has been pumped out. It is noted that for the sake of convenience the terms vacuum and evacuation have been used in the above description of the figures, but that these terms are also meant to include, respectively, a sub-atmospheric pressure and the generation thereof.

Claims: 12 CLAIMS 1. A method for removing a material from the surface of a product, wherein said product is at least partially placed in a liquid medium, characterized in that a gas, in particular air, is extracted from said material . 2. A method according to claim 1, wherein said gas is extracted by using a sub-atmospheric pressure, in particular a vacuum. 3. A method according to claim 1 or 2 , wherein an at least substantially stagnant liquid medium is used, in particular water. 4. A method according to claim 1, 2 or 3, wherein the product is placed in a container which is filled with said liquid medium, and wherein a sub- atmospheric pressure, in particular a vacuum, is applied above the liquid medium. 5. A method according to any one of the preceding claims 1 - 4, wherein said sub-atmospheric pressure varies between 0.01 and 17 bar, preferably between 0.1 bar and 0.2 bar (as an underpressure in comparison with the atmospheric pressure, which is generally approx. 1 bar) . 6. A method according to any one of the preceding claims 1 - 5, wherein said sub-atmospheric pressure is controllable, in particular infinitely variably so. 7. A method according to any one of the preceding claims 1 - 6, wherein a cheese or a part thereof is selected as the product, from which a protective 13 layer is removed. 8. A method according to any one of the preceding claims 1 - 6, wherein tubers, bulbs, stalk products or parts thereof, preferably potatoes, beets or bulbs, are selected as said product to be treated, from which dirt which is present thereon is removed. 9. A method according to any one of the preceding claims 1 - 6, wherein (perennial) plants or parts thereof, preferably peonies, are selected as the product, from which dirt which is present thereon is removed. 10. A method according to any one of the preceding claims 1 - 6, wherein fibrous products, in particular clothing and the like, are selected as the product, from which fibrous products dirt which is present thereon is removed. 11. A method according to any one of the preceding claims 1 - 6, wherein crockery, cutlery and the like are selected as said product, from which dirt which is present thereon is removed. 12. A method according to any one of the preceding claims 1 - 6, wherein a facade is selected as the product, from which dirt which is present thereon, in particular graffiti, is removed. 13. A method according to any one of the preceding claims 1 - 6, wherein (frozen) fish, meat or vegetables are selected as said product, and the fish, the meat or the vegetables are cleared of ice . 14 1 . A method according to any one of the preceding claims 1 - 6, wherein an archeological object is selected as the product, from which dirt which is present thereon is removed. 15. A method according to any one of the preceding claims 1 - 6, wherein a floor, in particular paving, is selected as the product, from which dirt which is present thereon is removed. 16. A device for carrying out a method according to any one of the preceding claims 1 - 15, which device comprises a container, which is to be filled with a liquid medium, for the product to be placed therein, as well as means for generating a sub- atmospheric pressure, in particular a vacuum, above said liquid medium. 17. A device according to claim 16, wherein said container comprises a supporting element for the product . 18. A device according to claim 16 or 17, wherein means for supplying a gas, preferably air, to the liquid medium are provided. 19. A device according to claim 16, 17 or 18 for carrying out the method according to claim 10, wherein said device is a washing machine. 20. A device according to claim 16, 17 or 18 for carrying out the method according to claim 11, wherein said device is a dishwasher. 21. A device according to claim 16, 17 or 18 for carrying out the method according to claim 12, wherein said device is a facade cleaner, in 15 particular a graffiti remover. 22. A device according to claim 16, 17 or 18 for carrying out the method according to claim 15, wherein said device is floor (paving) cleaner.

Inventors: WINTERS ANTONIUS PAUL LEO MARI, WINTERS, ANTONIUS, PAUL, LEO, MARIA
Applicants: HT IDEE BV, WINTERS ANTONIUS PAUL LEO MARI, HT IDEE B.V., WINTERS, ANTONIUS, PAUL, LEO, MARIA
Application year: 1999
Main classification: B08B3
IPC codes: A23C19, A23L1, A23N12, A47L15, B08B3, C11D11, D06F35, E01H1, E04G23