Method for cleaning a synthetic surface

Abstract

The invention relates to a method for cleaning a synthetic surface, in particular to remove metal dirt and/or particles therefrom, said method being characterized by the following steps: a) the synthetic surface is rinsed with deionized water; b) the synthetic surface is rinsed with electrolyzed water; and c) the synthetic surface is rinsed with deionized water.

Claims

1. A method for cleaning a plastic's surface so as to effect removing metallic particulate contaminants from the plastic's surface, comprising: a) rinsing the plastic's surface with deionized water, then b) rinsing the plastic's surface with electrolyzed water, wherein the plastic's surface is rinsed with anodic water followed by cathodic water so as to remove positive charges left on the plastic's surface by the anodic water, and then c) rinsing the plastic's surface with deionized water; wherein the rinsing of the plastic's surface with the deionized water, then the electrolyzed water, and then the deionized water effects cleansing of the plastic's surface to a predetermined cleanliness value.

2. The method as claimed in claim 1, wherein the anodic water has a pH of less than 7.

3. The method as claimed in claim 1, wherein the cathodic water has a pH of greater than 7.

4. The method as claimed in claim 1 further comprising adjusting a pH and/or a redox potential of the electrolyzed water to a predetermined value.

5. The method as claimed in claim 4, wherein in the step of adjusting the pH and/or the redox potential of the electrolyzed water, adjustment of the pH and/or the redox potential of the electrolyzed water is produced in an electrolysis cell which comprises two electrodes and into which water admixed with an electrolyte is introduced, and the pH and/or the redox potential of the electrolyzed water is adjusted by using a concentration of the electrolyte and/or an electrical current flowing between the two electrodes as control parameter(s).

6. The method as claimed in claim 1 wherein the rinsing of the plastic's surface in each of steps a), b), and c) lasts between 5 seconds and 600 seconds.

7. The method as claimed in claim 1 wherein the rinsing of the plastic's surface in each of steps a), b), and c) lasts for different durations.

8. The method as claimed in claim 1 wherein a temperature of the deionized water and/or of the electrolyzed water is between 10 C. and 70 C.

9. The method as is claimed in claim 6 wherein at least one of the rinsing of the plastic's surface in steps a), b), c) lasts between 15 and 90 seconds.

10. The method as claimed in claim 1 further comprising adjusting a pH and a redox potential of the electrolyzed water based on the metallic particulate contaminants such that each of the pH and the redox potential of the electrolyzed water is adjusted, independent of one another, to a respective predetermined value based on the metallic particulate contaminants.

Description

(1) With the aid of the appended drawings, an exemplary embodiment of the present invention is elucidated in more detail below. In the drawing,

(2) FIG. 1shows the schematic representation of an electrolysis cell,

(3) FIG. 2shows the schematic representation of a construction of an apparatus according to a first exemplary embodiment of the present invention, and

(4) FIGS. 3 and 4show schematic diagrams indicating the cleaning effect.

(5) FIG. 1 shows an electrolysis cell 1 having an anode chamber 2, in which there is an anode 4, and a cathode chamber 6, in which there is a cathode 8. Between the anode chamber 2 and the cathode chamber 6 there is an ion exchange membrane 10, which in the exemplary embodiment shown takes the form of an anion exchange membrane 10. Through an anode chamber feed 12, deionized water or distilled water, which may also be very pure or ultrapure water, is introduced into the anode chamber 2. At the same time, deionized water containing an electrolyte, which in the exemplary embodiment shown forms chloride ions, is passed into the cathode chamber 6 through a cathode chamber feed 14. It is shown diagrammatically in FIG. 1 that in the cathode chamber 6, in addition to the water (H.sub.2O), there are also ammonium ions (NH.sub.4.sup.+) and chloride ions (Cl.sup.).

(6) Between the anode 4 and the cathode 8 an electrical voltage is applied which accelerates the chloride ions (Cl.sup.) along the arrow 16 in the direction of the anode 4. They are able to pass through the ion exchange membrane 10, and are then within the anode chamber 2.

(7) In an alternative embodiment, instead of an anion exchange membrane, it is also possible to use a cation exchange membrane, so that positively charged cations can pass from the anode chamber 2 into the cathode chamber 6.

(8) Through an anode chamber drain 18, the constituents shown in FIG. 1 leave the anode chamber 2. These constituents are water, chloride ions (Cl.sup.), and hydronium ions (H.sup.+), which are generated by the electrical voltage between the anode 4 and the cathode 8. At the same time, in the anode chamber 2, ozone (O.sub.3) is formed, and likewise leaves the anode chamber 2 through the anode chamber drain 18.

(9) From an anode chamber drain 20, not only the water but also the ammonium ions (NH.sub.4.sup.+) and also the hydroxide ions (OH.sup.) leave the cathode chamber 8.

(10) From the concentration of the electrolyte from which the chloride ions (Cl.sup.) are formed in the example shown, and from the electrical current brought about by the voltage applied between the anode 4 and the cathode 8, it is possible to adjust the pH and also the redox potential of the electrolyzed water emerging from the anode chamber drain 18.

(11) FIG. 2 shows, schematically, an apparatus for carrying out a method for cleaning according to a first exemplary embodiment of the present invention.

(12) The apparatus possesses two electrolysis cells 1, each having an anode chamber 2 and a cathode chamber 6. Disposed between the two chambers in each case is an ion exchange membrane 10, which in the electrolysis cell 1 shown on the left in FIG. 2 takes the form of an anion exchange membrane, and in the electrolysis cell 1 shown on the right takes the form of a cation exchange membrane. In accordance with the arrows 16, therefore, anions in the left-hand electrolysis cell 1 are able to pass through the ion exchange membrane 10, whereas cations in the right-hand electrolysis cell 1 are able to cross from the anode chamber 2 into the cathode chamber 6.

(13) The apparatus shown in FIG. 1 possesses an anolyte mixing tank 22. In this tank, deionized water, provided via a supply line 24, is mixed with an anolyte, before being fed via the anode chamber feed 12 into the anode chamber 2 of the electrolysis cell 1 shown on the right in FIG. 2. Deionized water is supplied through the cathode chamber feed 14.

(14) Cathodic water is produced in the electrolysis cell shown on the right in FIG. 2, and is introduced via a cathode line 26 into a cathode tank 28. From there it can be supplied to an applicator 30 by which it is applied to a plastics surface to be cleaned.

(15) The apparatus shown in FIG. 2, moreover, possesses a catholyte mixing tank 32. In this tank, deionized water supplied via the supply line 24 is mixed with a catholyte, before being introduced via the cathode chamber feed 14 into the cathode chamber 6. Deionized water is introduced via the anode chamber feed 12 into the anode chamber 2 of the electrolysis cell 1 shown on the left in FIG. 2. From the anode chamber drain 18, the anodic water produced in the left-hand electrolysis cell is introduced through an anode line 34 into an anode tank 36, from which it may likewise be supplied to the applicator 30.

(16) FIGS. 3 and 4 show schematically the cleaning effect of a method according to one exemplary embodiment of the present invention. The task in this case is the removal of iron contaminants from a component made of polycarbonate. What is plotted in each case is B, the redox potential in millivolts (mV), against A, the pH. The solid lines each contain a number in a rectangular box. This number denotes the percentage fraction of the iron contaminants which it has been possible to remove using the respective method. For example, in the case of the result shown in FIG. 3 for a method, 25% of the iron contaminants are removed, at a pH of 5.2 and a redox potential of 422 mV.

(17) In the case of the method whose result is shown in FIG. 3, the surface is treated with the respective liquid for 15 seconds at a temperature of 22.1 C., whereas for the method whose result is shown in FIG. 4, the treatment occurs with the respective liquid for 180 seconds at a temperature of 70 C. It can be seen that with identical ranges of the redox potential B and of the pH A, the longer exposure time to the respective liquid allowed significantly greater proportions of the iron soiling and contaminants to be removed.

LIST OF REFERENCE SYMBOLS

(18) 1 Electrolysis cell 2 Anode chamber 4 Anode 6 Cathode chamber 8 Cathode 10 Ion exchange membrane 12 Anode chamber feed 14 Cathode chamber feed 16 Arrow 18 Anode chamber drain 20 Cathode chamber drain 22 Anolyte mixing tank 24 Supply line 26 Cathode line 28 Cathode tank 30 Applicator 32 Catholyte mixing tank 34 Anode line 36 Anode tank