EP1775354A1 - Process for cleaning metal surfaces - Google Patents

Abstract

Method for cleaning parts made from aluminum or magnesium comprises contacting the parts with a first aqueous solution containing 0.2-0.5 % of a first composition made from an inorganic acid, two fatty alcohol-ethylene oxide-propylene oxide adducts (fatty alcohol-EO-PO) and a fatty alcohol ethoxylate and contacting the surface with a second aqueous solution containing 0.2-1.5 % of a second composition made from sodium hydroxide and phenol ethoxylate phosphate.

Description

The present invention relates to a process for the purification of metal-containing parts, in particular aluminum or magnesium-containing parts, and the use of cleaning solutions for metal-containing parts, in particular aluminum or magnesium-containing parts.

Many metal-containing products that are either entirely made of metals, such as aluminum or magnesium, or have a metal-containing surface are contaminated in the course of their use or have over time on aging. Although these parts may not be impaired in their function, it is nevertheless often necessary, for example for optical reasons, to clean the parts. Such parts are, for example, used in vehicle construction, such as. Transmission, engine or body parts, also come components in aerospace technology, washing machines, dishwashers, etc., into consideration, so all areas that use aluminum or magnesium-containing components ,

Not least for environmental reasons there is a long time the need to replace dirty parts or components not simply by new identical parts, but to clean the parts, on the one hand the disposal costs of the old parts and on the other hand energy and raw materials for the production of new spare parts save up. Even compared to indirect recycling as a raw material, the direct recycling of parts offers an advantage in terms of saving energy and resources.

Furthermore, often new spare parts for the same old components are not or no longer available in stock, so that they would then have to be rebuilt with considerable effort. However, often not only the necessary tools and production machines are missing, but also information about the actual composition of the parts or components. Therefore, the old products and components can not be replaced only by newly manufactured components. Also for this reason, there is a need to clean the old soiled components and return them to their original purpose.

Furthermore, the processing of old parts has the advantage that the components in question need not be produced in stock, which also manufacturing and storage costs can be saved.

The prerequisite for effective cleaning and recycling of used parts is that these cleaned parts reach all the qualitative standards of a new part. Especially with complex components in automotive parts, such as gearboxes, axles, motors and attachments, the quality of parts is of crucial importance. In addition to a qualified dismantling of the parts, it is particularly important to clean these parts, some of which are very old and correspondingly soiled or even corroded, in such a way that the function and structure of the material is not changed.

For obvious reasons, in particular, aluminum and magnesium parts can not be blasted with sand or other media for cleaning, since in these cleaning methods there is a risk that minute particles are stored in the parts or accumulate on the parts, and thereby can greatly affect the property or function of the parts.

In the prior art, it is also known to provide old parts with a paint, but this is not always possible for reasons of recycling and temperature dissipation and not desired.

However, there is not only the need to effectively clean used metal-containing parts. Also in the initial production of parts made of metal, for example. Of aluminum or magnesium, or of parts that have a metal-containing surface, they are contaminated during the production process. For optimum functionality and optical reasons, therefore, often newly manufactured components must be offset by a cleaning in a visually new state.

In the prior art, no satisfactory cleaning method are known, with which such parts can be cleaned efficiently because on the one hand often the material surface - and thus usually the function of the part - is attacked and on the other hand, the part is only insufficiently cleaned.

The object of the present invention is therefore to provide a new cleaning method for reusable parts or products, with which the surface the parts are freed of dirt deposits and signs of aging without affecting or changing the function and material of the surface.

1. a) In-Kontakt-Bringen der metallhaltigen Teile mit einer ersten wässrigen Lösung, welche 0,2 bis 50 % einer Zusammensetzung aufweist, die von 0,2 % bis 50 % einer ersten Zusammensetzung enthält, welche eine anorganische Säure, zumindest zwei Fettalkohol-Ethylenoxid-Propylenoxid-Addukte (Fettalkohol-EO-PO) und ein Fettalkohol-Etoxylat aufweist;
2. b) Einbringen des Produktes in eine Lösung, welche 0,2 bis 15 % einer Zusammensetzung enthält, die Natriumhydroxid, und Phenolethoxylat-Phosphat.

This object is achieved in the present case by a method which includes the following steps:

1. a) contacting the metal-containing parts with a first aqueous solution having 0.2 to 50% of a composition containing from 0.2% to 50% of a first composition comprising an inorganic acid, at least two fatty alcohol Ethylene oxide-propylene oxide adducts (fatty alcohol EO-PO) and a fatty alcohol ethoxylate;
2. b) introducing the product into a solution containing 0.2 to 15% of a composition, the sodium hydroxide, and phenol ethoxylate phosphate.

The object is further achieved by the use of an aqueous solution containing from 0.2% to 50% of a composition comprising an inorganic acid, at least two fatty alcohol-ethylene oxide-propylene oxide adducts (fatty alcohol EO-PO) and a fatty alcohol ethoxylate and by the use of an aqueous solution having from 0.2% to 15% of a composition comprising sodium hydroxide and phenol ethoxylate phosphate for purifying metal-containing parts.

The object underlying the invention is completely solved in this way.

With the new process, even heavily soiled metal-containing surfaces or metal-containing parts can be thoroughly cleaned and thus lightened.

The two steps ensure that the dirt present on the surface of the metal-containing part is dissolved by introduction into the first solution and then cleaned efficiently by introduction into the second solution.

The inventors of the present process have developed the cleaning process in numerous experiments and optimized it with the given steps and the cleaning solutions used therein. It was also found that the respective compositions of the first and the second aqueous solution or their percentage content in the aqueous solution can be optimally adapted to the particular part to be cleaned. This is particularly important in view of the various metal alloys from which the parts are made, since thus the parameters can be optimally adjusted for each metal or metal alloy, in particular of aluminum or magnesium alloys. However, the basic principle of the solutions is the same for the different metal or metal alloys.

With the method according to the invention, efficient cleaning of, for example, gearboxes or transmission parts, engines and engine parts, i.a. Components were made, whereby the parts could be visually and functionally restored to their original state.

The basis for the aqueous solutions is water, which is either decalcified water, drinking water or demineralized water.

In a further preferred embodiment, the composition of step a) to be applied in an aqueous solution comprises 5% to 80% of an inorganic acid, 0.1% to 3% of a fatty alcohol EO-PO C ₁₀ -C ₁₂ 6EO 8PO, 3% to 20% of a fatty alcohol EO-PO C ₈ -C ₁₀ 5-6EO 3-4PO, 1% to 5% of a fatty alcohol C ₈ 4EO, 3% to 25% non-ionic surfactants and inhibitors.

In this case, the inorganic acid may be selected between sulfuric acid, phosphoric acid or nitric acid.

In numerous experiments, these concentration ranges of the components of the composition have been found to be optimal for the first step, as with This composition a dissolution of the dirt surface can be achieved.

The composition is composed as in the above-mentioned range and used for use in step a) as an aqueous solution having 0.2% to 50% of the described first composition.

The non-ionic surfactants are surface-active substances that reduce the surface tension of the water in the aqueous solution, thereby enabling better wetting of the parts to be cleaned. The surfactants have an emulsifying and dispersing effect of fats and dirt particles. The fatty alcohol EO-PO adducts used have the additional advantage that they have a foam-regulating property and damp any foam occurring.

The inhibitors, which prevent the material to be purified from being attacked by the aqueous solution, are contained in the composition at from about 0.05% to 1%. The selection of the inhibitors is adjusted depending on the material to be cleaned and the first solution used. As inhibitors, for example, aluminum or triazoles can be used.

In a further embodiment it is preferred if the second composition of step b) to be used in an aqueous solution comprises 10% to 40% sodium hydroxide, 0.5% to 10% phenol ethoxylate phosphate, 0.5 to 8% phosphates, and salts and silicates having.

Numerous experiments have shown that with these concentration ranges of the components of this composition in conjunction with the first solution, an efficient cleaning of the detached surface can be achieved.

Also this second composition is assembled in the above-described range and prepared for use in step b) as an aqueous solution having from about 0.2% to about 15% of the described second composition.

In particular, the present in the composition of silicates and salts provide the highest possible pH, which ensures a good soil removal. The alkali carriers in conjunction with the phosphates are also responsible for corrosion protection.

As suitable salts, for example, phosphates, borates and carbonates can be used, as suitable silicates, for example. Sodium silicate, sodium hydroxide, potassium, etc. The additional amounts of salt to be used are, for example -. U.a. depending on the metal to be cleaned, or the alloy to be cleaned - about 10% to 40%, that of the silicates to be used, for example. From 20% to 50%.

In a preferred embodiment, after the first step a) and after the second step b), i. one or more rinsing steps a ') and b') are provided after the surface has been dissolved and after the loosened surface has been cleaned.

This measure has the advantage that the chemical processes taking place in the purification steps can be interrupted directly by the rinsing steps between the individual purification steps, without mixing the cleaning solutions. If necessary, the rinsing steps can be repeated.

As a suitable agent for the rinsing steps, water is preferably used which is selected from the group consisting of decalcified water, drinking water or demineralized water. In this case, it is further preferred if the rinsing takes place via an immersion bath or else by spraying.

In the process according to the invention, it is generally preferred if the individual steps a), a '), b) and b') take place in a dipping bath.

This embodiment has the advantage that complete wetting of the parts to be cleaned is ensured, so that all surfaces come into uniform contact with the cleaning solutions.

In this case, provision may be made, in particular, for either the immersion baths or the parts in the immersion baths to be moved, so that, for example, air bubbles which have formed on the parts when the parts are introduced into the immersion bath are dissolved, and the wetting of the parts as a whole is relieved. Thus, for example, the pressure flood method can be used in which the water is removed from the tank by means of a pump and a certain voluntary movement is brought into the bath via a nozzle. In this case, a targeted mechanical effect on the parts can be brought by the part movement and the arrangement of the nozzles.

In a preferred embodiment it is provided that the parts in the immersion bath are treated simultaneously with ultrasound in at least one of the cleaning steps.

This measure has the advantage that additional detachment and decomposition effects are exerted on the dirt particles by the ultrasonic waves, which can accelerate the cleaning of the surface. The cleaning effect of the ultrasonic waves is based on cavitation: The vibrations cause in the sonicated liquid smallest cavities, which collapse immediately. This creates strong currents and turbulence, which almost burst the existing dirt on the cleaning material.

In the method according to the invention is further preferred if the purification steps are carried out at a temperature of about 10 ° C to about 90 ° C.

In optimizing the method according to the invention, it has been found for magnesium alloys that the higher the magnesium content of the part to be cleaned, the higher the temperature has to be.

The temperature which is used during the process depends - as well as the concrete composition - in particular on the degree of contamination and the respective metal or metal alloy and can be specially adjusted to this.

It is further preferred if the individual steps are carried out over a period of in each case from about 5 seconds to 20 minutes, and in particular if step a) and gg. Step a ') and step b') in each case over a period of about 5 seconds to about 10 minutes, and step b) over a period of about 5 seconds to about 20 minutes.

The duration of the individual cleaning steps depends on the degree of contamination, the type of contamination and the part to be cleaned, or its composition and can be varied accordingly.

• c) In-Kontakt-Bringen des metallhaltigen Teils mit einer dritten wässrigen Lösung, die 0,2 % bis 2,5 % einer Zusammensetzung aus Mineralöl, Salzen, organischen Säuren, Fettalkoholen, Inhibitoren und Emulgatoren aufweist.

In a preferred embodiment, it may further be provided that a passivation step is provided after a last rinsing step:

• c) contacting the metal-containing part with a third aqueous solution comprising 0.2% to 2.5% of a composition of mineral oil, salts, organic acids, fatty alcohols, inhibitors and emulsifiers.

It is preferred if this passivation step is carried out either by introducing the purified part into a dipping bath of the aqueous solution or by spraying, and in particular if the introduction into a dipping bath is carried out for a period of about 5 seconds to about 10 minutes.

For the passivation normal mineral oils and glycerine, as well as phosphates, carbonates and borates can be used.

In all steps, water is used as the basis of the particular aqueous solution, which is selected from the group consisting of decalcified water, drinking water or demineralized water.

With the new use of the aqueous solutions disclosed for the first time in the present application, to the knowledge of the inventors, a simple, fast and thorough cleaning of soiled metal-containing parts can advantageously be achieved, which was hitherto unknown in the prior art.

Fig. 1

ein Fließdiagramm einer Ausführungsart des erfindungsgemäßen Verfahrens.

In the following, the method with reference to the description and the figure will be explained in more detail. It shows:

Fig. 1

a flow diagram of an embodiment of the method according to the invention.

In Fig. 1, the process flow of a preferred embodiment of the method according to the invention is shown schematically with reference to a flow chart.

Thereafter, an aqueous solution comprising from 0.2 to 50% of a composition comprising from 5 to 80% sulfuric or phosphoric acid, from 0.1 to 3% of a first fatty alcohol EO-PO, from 3 to 20% of a second is provided first Fatty alcohol EO-PO, 1 to 5% of a third fatty alcohol, and 3 to 25% non-ionic surfactants and inhibitors. To carry out the first step, namely to dissolve the surface, the solution is introduced into a dip tank.

Subsequently, the metal-containing part to be cleaned, for example a gear, a gear part or engine part, etc., is introduced into the dip tank filled with the first aqueous solution. Depending on the nature of the part, ie depending on the alloy, and depending on the degree of contamination of the part, either the basin or the solution in the pool or present in the dip tank to be cleaned part can be moved in addition, for example. By shaking / shaking. Furthermore, the pressurized flood method can be used here in which water is removed from the basin by means of a pump and a targeted movement is brought into the bath via a nozzle. It is also possible to treat the part to be cleaned additionally (or alternatively) with ultrasound. As already mentioned above, the vibrations in the sonicated liquid cause the smallest cavities, which immediately collapse again. This creates strong currents and turbulence, which almost burst the existing dirt on the cleaning material. The use of ultrasound also depends on the degree of soiling of the part and on the metallic composition of the cleaned part.

The time required to treat the part in this solution can be between 5 seconds and 10 minutes, with a choice of between 10 and 90 ° C for this step. The time period and the temperature to be applied also depend on the dirt content of the parts, the materials and the flow rates. The exact composition of the chemistry is tuned as a whole with the temperature of the solution and the residence time of the product in the solution.

As can also be seen from the flow diagram from FIG. 1, in a next step the product is taken out of the first aqueous solution and rinsed either by means of a dip bath or by spraying. For rinsing while clear water, ie either drinking water, decalcified water or demineralized water used. By rinsing, the overall chemical process of the first step is interrupted. If necessary, the rinsing step can be repeated once or several times. Also during the rinsing steps or a temperature of between 10 and 90 ° C and a residence time of the parts in the rinsing medium of between 5 seconds and 10 minutes can be applied. In this case, the temperature and the residence time will depend in particular on the previously applied temperature and on the residence time of the product in the first solution.

In a next step, the part to be cleaned is returned to a dip tank filled with a second aqueous solution. The aqueous solution comprises about 0.2 to 15% of a composition comprising 10 to 40% sodium hydroxide, 0.5 to 10% phenol ethoxylate phosphate, 0.5 to 8% phosphates, as well as salts and silicates.

By introducing the part into this solution, a cleaning of the area dissolved in the first step takes place. The residence time of the parts in this second solution is from 5 seconds to 20 minutes and depends on the previously used steps, the nature of the material and the degree of soiling.

As can be seen from FIG. 1, after this cleaning step, a further rinsing step is carried out, which, like the first rinsing step, can likewise be carried out, for example, by an immersion bath or by spraying. The temperature used in the second rinsing step and the residence time of the rinsing product also depend on the temperatures used previously and on their residence time.

Optionally, after this last rinsing step, a passivation step can take place in order to protect the cleaned part and thus its function against environmental influences. The application of a passivation layer may be particularly desirable if the part is to be stored for a longer period of time after the cleaning, if necessary. The passivation layer does not impair the subsequent reuse of the part or its assembly and its function. Under normal conditions, the effect of the passivation should not lose its protective effect within six months - under indoor conditions and without major fluctuations in temperature. The passivation solution used is a solution which comprises 0.2 to 5% of a composition comprising mineral oil, salts, organic acids, fatty alcohols, inhibitors and emulsifiers. Passivation solutions are well known in the art and can be selected by one skilled in the art based on the underlying material.

The residence time of the material in the passivation solution is also between 50 seconds to 10 minutes when using a dip bath, whereby here too a temperature is tuned in accordance with the material and in coordination with previously applied temperatures of the cleaning steps.

The individual steps are to be adapted to the respective magnesium and aluminum alloys and adapted, since the success of the cleaning or whitening of the surface taking into account the functional surfaces of the composition used, their percentage use in the solution, the temperature, the residence time in the Bad and possibly applied motion / ultrasound of either the part or the medium is dependent.

With the process just described, heavily soiled aluminum and magnesium alloys have been successfully cleaned, making this process particularly suitable for the recycling of aluminum or magnesium-containing parts.

Parts or products that can be cleaned in this way are all metal-containing products or components, in particular parts that consist of aluminum or magnesium, or of aluminum or magnesium alloys, or have a surface with such metals or alloys, such as vehicle components of automobiles, trucks, but also in the field of dishwashers and washing machines and the field of aerospace engineering. This list is intended to be merely exemplary of the parts which may be cleaned or brightened in the scope of the present application.

It is understood that several components can be cleaned simultaneously, i. Several parts are simultaneously added to the aqueous solutions and purified. In this way, the efficiency of the purification process, i. in particular the run, be increased.

Claims (16)

Process for cleaning metal-containing parts, in particular parts containing aluminum or magnesium, comprising the following steps: a) contacting the metal-containing parts with a first aqueous solution having from 0.2% to 50% of a first composition comprising an inorganic acid, further at least two fatty alcohol-ethylene oxide-propylene oxide adducts (fatty alcohol EO -PO) and a fatty alcohol ethoxylate; b) introducing the metal-containing portion after dissolution of the surface into a second aqueous solution comprising from 0.2% to 15% of a second composition comprising sodium hydroxide and phenol ethoxylate phosphate. A method according to claim 1, characterized in that the first composition comprises 5% to 80% of inorganic acid, 0.1% to 3% of a C ₁₀ -C ₁₂ 6EO 8PO fatty alcohol EO-PO, 3% to 20% of a C ₈ - C ₁₀ 5-6EO, 3-4PO fatty alcohol EO-PO, 1% to 5% fatty alcohol C ₈ 4EO, 3% to 25% non-ionic surfactants and inhibitors. A method according to claim 1 or 2, characterized in that the second composition comprises 10% to 40% sodium hydroxide, 0.5% to 10% phenol ethoxylate phosphate, 0.5 to 8% phosphates, as well as salts and silicates. Method according to one of claims 1 to 3, characterized in that after step a) a further step a 'and after the second step b) a further step b' are provided, in which the product is rinsed in each case with clean water. A method according to claim 4, characterized in that the rinsing takes place either via an immersion bath or by spraying. Method according to one of claims 1 to 5, characterized in that the individual steps a) and b) or a), a '), b) and b') in each case in one. Dipping bath done. A method according to claim 6, characterized in that at least one of the steps takes place at the same time a movement of the parts or the aqueous solutions. A method according to claim 6 or 7, characterized in that at least one of the steps simultaneously ultrasonic is used. Method according to one of claims 1 to 8, characterized in that in the individual steps, a temperature of about 10 ° C to about 90 ° C is set. Method according to one of claims 1 to 9, characterized in that the individual steps are carried out for a duration of about 5 seconds to about 20 minutes. A method according to claim 10, characterized in that step a) and optionally step a ') and step b') are each carried out over a period of about 5 seconds to about 10 minutes and step b) over a period of about 5 seconds to about 20 minutes. Method according to one of claims 1 to 11, characterized in that after step b) a further step is provided: c) contacting the purified metal-containing portion with an aqueous solution comprising 0.2% to 2.5% of a composition of mineral oil, salts, organic acids, fatty alcohols, inhibitors and emulsifiers. Use of an aqueous solution containing from 0.2% to 50% of a composition comprising an inorganic acid, at least two fatty alcohol-ethylene oxide-propylene oxide adducts (fatty alcohol EO-PO) and a fatty alcohol ethoxylate, for purifying metal-containing parts , in particular of aluminum or magnesium-containing parts. Use according to claim 13, characterized in that the composition comprises 5% to 80% of inorganic acid, 0.1% to 3% of a C ₁₀ -C ₁₂ 6EO 8PO fatty alcohol EO-PO, 3% to 20% of a C ₈ C ₁₀ 5-6EO, 3-4PO fatty alcohol EO-PO, 1% to 5% fatty alcohol C ₈ 4EO, 3% to 25% nonionic surfactants and inhibitors. Use of an aqueous solution comprising from 0.2% to 15% of a composition comprising sodium hydroxide and phenol ethoxylate phosphate for cleaning metal-containing parts, especially parts containing aluminum or magnesium. Use according to claim 15, characterized in that the composition comprises 10% to 40% sodium hydroxide, 0.5% to 10% phenol ethoxylate phosphate, 0.5% to 8% phosphates, as well as salts and silicates for cleaning metal-containing parts, in particular of aluminum or magnesium-containing parts.

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