EP0761843A2 - Use of (C1-C5) alkyl esters of aliphatic (C8-C22) monocarboxylic acid for cleaning metal objects - Google Patents

Abstract

1-5 C alkyl ester(s) (I) of 8-22 C monocarboxylic acid(s) are used for cleaning metal articles or producing cleaning agents for these. Also claimed are the cleaning agents contg. (I) for cleaning metal articles, preferably vehicle parts, especially engines or wheel rims; and the cleaning method.

Description

The invention relates to the use of (C ₁ -C ₅ ) alkyl esters of aliphatic (C ₈ -C ₂₂ ) monocarboxylic acids. The invention further relates to an agent and a method for cleaning metallic objects.

EP-B1-435 943 discloses the use of (C ₁ -C ₅ ) alkyl esters of aliphatic (C ₈ -C ₂₂ ) monocarboxylic acids for removing printing ink from printing presses. The application rollers or printing blankets made of rubber are treated with an agent which contains these alkyl esters.

Liquid metal cleaning agents usually contain large amounts of organic solvents, which are mostly selected from the groups of unsubstituted and substituted hydrocarbons, as well as so-called white spirit or VOC chemicals (volatile organic chemicals). In the course of the ongoing environmental discussion and tightening legal regulations, such solvents are to be largely replaced by less hazardous chemicals.

The object of the invention is therefore to largely exclude or completely avoid the disadvantages described in the known metal cleaning agents. As a result, the usual cleaning processes for metallic objects are also to be improved.

This object is achieved by the use of the esters mentioned at the outset according to claim 1, the cleaning agent according to claim 11 and a corresponding cleaning process. Preferred embodiments of these solutions are described in dependent claims 2 to 10 and 12 to 14. The wording of all claims is incorporated by reference into the content of the description.

According to the invention, the (C ₁ -C ₅ ) alkyl esters of aliphatic (C ₈ -C ₂₂ ) monocarboxylic acids or their mixtures are used for cleaning metallic objects or for producing a cleaning agent for metallic objects. In this way, a so-called metal cleaner or - in common parlance - "industrial cleaner" can be produced, in which a product obtainable from so-called renewable raw materials can be used. This opens up a new area of application for such products. The esters used are non-toxic and biodegradable. They also have a high flash point. From these few details, the decisive advantages over conventional cleaning agents, which contain a large amount of the organic solvents mentioned, result.

The esters mentioned or their mixtures can in principle be used to clean all metallic objects. Under certain circumstances, these metallic objects can also be at least partially coated with other materials, for example, be painted. In addition to the cleaning of machines, a preferred area of application of the invention is in particular the cleaning of motor vehicle parts and possibly motor vehicles themselves, the esters being used in particular as engine cleaners or wheel rim cleaners.

All esters that fall under the above definitions can in principle be used. They are essentially the (C ₁ - C ₅ ) alkyl esters of alkane carboxylic acids and their unsaturated representatives with 8 - 22 C atoms. These esters of the so-called middle and higher fatty acids (up to C ₂₂ ) can be handled for the use according to the invention, the esters liquid at room temperature being preferred.

The esters can be prepared in a known manner by esterification of the corresponding monocarboxylic acid or a mixture of such acids with the corresponding alcohol. The esters can also be obtained in the usual way by transesterification (alcoholysis) of the glyceride (fat / oil) concerned with the corresponding (C ₁ -C ₅ ) alcohol. Important representatives of the esters or mixtures of such esters which can be used according to the invention are already being produced and sold on a large scale.

Although there is basically no restriction on the raw materials used, rapeseed, sunflower, coconut, oil palm kernel and castor oil (seeds of castor bean) are particularly suitable as raw materials for the esters which can be used according to the invention.

In preferred embodiments of the invention (C ₁ -C ₃ ) alkyl esters of (C ₈ -C ₂₂ ) monocarboxylic acids or mixtures thereof are used. In particular, the methyl esters of these monocarboxylic acids can be used.

Furthermore, the esters of aliphatic (C ₁₀ -C ₂₂ ) monocarboxylic acids are preferred, the esters of aliphatic (C ₁₆ -C ₂₀ ) monocarboxylic acids in particular being usable in accordance with the invention.

In principle, both the esters of aliphatic, saturated monocarboxylic acids and the esters of aliphatic, unsaturated monocarboxylic acids can be used in the invention. The esters of aliphatic, saturated monocarboxylic acids (and their mixtures) are preferred on account of the good availability and the mostly sufficient cleaning action. The use of esters of aliphatic, unsaturated monocarboxylic acids or, preferably, of mixtures of esters of aliphatic, saturated monocarboxylic acids with esters of aliphatic, unsaturated monocarboxylic acids is recommended when an increased cleaning action is desired, which can be associated with the proportion of esters of aliphatic, unsaturated monocarboxylic acids . The use of such mixtures is also advantageous if they result from the production of a corresponding fat or oil, so that further processing and separation steps can be omitted. If esters of aliphatic, unsaturated monocarboxylic acids are used, monounsaturated to triunsaturated monocarboxylic acids are preferably provided. This can be, for example, oleic acid, erucic acid, linoleic acid or linolenic acid. As already mentioned, esters of ricinoleic acid can also preferably be used.

According to the invention, the esters mentioned can be used not only as such, ie undiluted (if appropriate with suitable additives), but also in a mixture with at least one organic solvent. It can be done in such a way that the previously known metal cleaning agents with organic solvent the proportion of organic solvent is replaced by adding the corresponding ester or ester mixture. In all of these preferred embodiments, the aforementioned hydrocarbons, mineral spirits or VOC chemicals are used as organic solvents, the structure and composition of which are known to the person skilled in the art and which can be purchased. In all embodiments with the addition of an organic solvent, so-called high-boiling solvents are preferably used in order to ensure the highest possible flash point of the mixture obtained. In particular, according to the invention, a flash point> 100 can be achieved with such mixtures, which has a significant advantage over the conventional cleaning agents of the prior art. Accordingly, less stringent hazard regulations must be observed in the manufacture, transport, storage and use of the cleaning agents according to the invention than has hitherto been necessary with the conventional cleaning agents. In the context of the invention, the mixture of ester and organic solvent is selected so that the highest possible flash point is achieved taking into account other required properties.

When using the esters in a mixture with organic solvent, preferably at least 10% by volume of ester, in particular at least 50% by volume of ester, is provided. In principle, the largest possible proportion of organic solvent should of course be "replaced" by the esters.

In further preferred embodiments of the invention, an aqueous emulsion is used, which by adding water and at least one emulsifier to the ester or the ester mixture or to the mixture of ester and organic solvent is available. As a result, the advantageous properties of water can be incorporated into the mixture obtained overall, ie the emulsion. To prepare the emulsion, in particular 10-90% by volume of water and 1-10% by weight of emulsifier (based on the total weight of the emulsion) are added to the ester or the ester mixture or to the mixture of ester with organic solvent. Within the ranges mentioned, it is preferred if 10-50 vol.% Water or 2-5 wt.% Emulsifier (based on the total weight of the emulsion) is added. The known compounds are suitable as emulsifiers, nonionic emulsifiers being preferred.

According to the invention, at least one corrosion inhibitor can be provided which prevents the metallic object from being attacked by the cleaning agent. Corrosion inhibitors of this type are added in an amount of up to 3% by weight, preferably between 0.5 and 2% by weight, based on the total weight of the cleaning agent used. Compounds which are already known, such as, in particular, aliphatic primary amines, can also be used as corrosion inhibitors.

Finally, in other preferred embodiments of the invention, at least one surface-active agent can be provided, which is added in particular in an amount of up to 10% by weight, preferably between 0.3 and 3% by weight, based on the total weight of the cleaning agent used. Conventional compounds can also be used here, for example polyglycol ethers of long-chain aliphatic alcohols.

For the sake of completeness, it should be mentioned that, depending on the field of use used, further additives such as stabilizers or antioxidants can be used in combination with the esters according to the invention.

As already mentioned, the invention also relates to a preferably liquid cleaning agent for metallic objects, which is preferably provided for cleaning machines and for cleaning motor vehicles and their parts, such as in particular engines or rims. This cleaning agent is characterized in that it contains at least 10% by volume of a (C ₁ -C ₅ ) alkyl ester of an aliphatic (C ₈ -C ₂₂ ) monocarboxylic acid or mixtures of such esters.

Further features of this cleaning agent result from the features already described when using the esters, wherein these features can be implemented both individually and in combination with one another.

Finally, the invention relates to a cleaning method for metallic objects, which is preferably provided for cleaning motor vehicles or their parts, such as in particular engines or rims. This method is characterized by the use already described or by the use of the cleaning agent described. Reference is expressly made to the corresponding passages in the description.

In principle, the method according to the invention can be carried out in the usual way for cleaning the metallic objects, the esters mentioned being used. In preferred embodiments, the cleaning agent is applied to the metallic object to be cleaned, for example the engine or the rim of the motor vehicle, in particular sprayed on. Then the cleaning agent, ie usually the cleaning solution, is left to act for a certain time. Then it is preferably rinsed with water or sprayed off preferably removed with steam again from the metallic object. Then it can be dried if necessary.

In order to improve the cleaning effect, a mechanical cleaning treatment can additionally be carried out during at least part of the contact time. In particular, this involves wiping and / or brushing, for example to additionally mechanically remove the dirt that has been detached from the cleaning agent. If appropriate, the process can also be carried out by first pretreating with the cleaning agent according to the invention, possibly with a longer exposure time, and then performing a further cleaning with other customary washing or cleaning agents.

The described features and further features of the invention result from the following examples in conjunction with the subclaims. The individual features can be implemented individually or in combination with one another.

example 1

To clean car rims, a mixture of methyl esters of (C ₁₆ - C ₂₀ ) saturated and unsaturated monocarboxylic acids available from castor oil is used. Such a mixture is commercially available as an industrial base material.

The ester mixture mentioned has the following properties Melting temperature -10 ° C Vapor pressure (20 ° C) <0.01 mbar Density (20 ° C) 0.89 g / cm ³ Viscosity at 25 ° C 6 - 7 mm ² / s Flash point over non-toxic. 100 ° C

The mixture described is sprayed onto the rims heavily soiled by normal road traffic. After a few minutes of exposure, the rims are sprayed with steam and dried. The cleaning result can be assessed as very good in comparison to conventional rim cleaners. As already described, in the case of particularly stubborn dirt, the rim can also be brushed after the cleaning agent has been applied.

Example 2

A 50:50 (vol.%) Mixture is prepared from the mixture of methyl esters of saturated and unsaturated (C ₁₆ -C ₂₀ ) monocarboxylic acids and mineral spirits described in Example 1 and used in the same manner as in Example 1. The cleaning result is also very good here.

Example 3

The mixture used in Example 2 is emulsified in 50% by volume of water together with an emulsifier (5% by weight, based on the total weight). If necessary, a corrosion inhibitor and a surface-active agent can be added. Here too, car rims are treated in the same way as in Examples 1 and 2. The cleaning result is also assessed as very good in this third attempt.

Example 4

The mixtures described in Examples 1 to 3 are used in the usual way for engine washing in a motor vehicle used. Very good results are also achieved in comparison with conventional engine cleaners.

Claims (14)

Use of (C ₁ - C ₅ ) alkyl esters of aliphatic (C ₈ -C ₂₂ ) monocarboxylic acids or mixtures of such esters for cleaning metallic objects or for producing a corresponding cleaning agent. Use according to claim 1, characterized in that the metallic objects are industrial machines or motor vehicle parts, in particular motors or rims. Use according to claim 1 or claim 2, characterized in that the esters are (C ₁ - C ₃ ) alkyl esters, in particular methyl esters. Use according to one of the preceding claims, characterized in that it is esters of aliphatic (C ₁₀ - C ₂₂ ) monocarboxylic acids, in particular esters of aliphatic (C ₁₆ - C ₂₀ ) monocarboxylic acids. Use according to one of the preceding claims, characterized in that it is esters of aliphatic, saturated monocarboxylic acids. Use according to one of claims 1 to 4, characterized in that it is a mixture of esters of aliphatic, saturated monocarboxylic acids with esters of aliphatic, unsaturated monocarboxylic acids, in particular monounsaturated to triunsaturated monocarboxylic acids being provided. Use according to one of the preceding claims, characterized in that the esters are used in a mixture with at least one organic solvent, in particular a high-boiling organic solvent, preferably at least 10% by volume of ester, in particular at least 50% by volume, in a mixture with organic solvent. Esters are provided. Use according to one of the preceding claims, characterized in that an aqueous emulsion obtainable by adding water and at least one emulsifier is used, preferably 10-90% by volume of water, in particular 10-50% by volume of water, and 1-10% by weight, in particular 2-5% by weight, of emulsifier, based on the total weight of the emulsion, have been added. Use according to one of the preceding claims, characterized in that at least one corrosion inhibitor is provided, preferably in an amount of up to 3% by weight, in particular between 0.5 and 2% by weight on the cleaning agent used is added. Use according to one of the preceding claims, characterized in that at least one surface-active agent is provided, which is preferably added in an amount of up to 10% by weight, in particular between 0.3 and 3% by weight, based on the cleaning agent used. Agent for cleaning metallic objects, preferably motor vehicle parts such as in particular engines or rims, characterized in that it contains at least 10% by volume of a (C ₁ -C ₅ ) alkyl ester of an aliphatic (C ₈ -C ₂₂ ) monocarboxylic acid or mixtures of such esters. Cleaning agent according to claim 11, characterized in that esters according to claims 3 to 6 are contained. Cleaning agent according to claim 11 or claim 12, in the form of a mixture with at least one organic solvent according to at least one feature of claim 7 and / or in the form of an aqueous emulsion according to at least one feature of claim 8. Cleaning agent according to one of claims 11 to 13, characterized by the addition of corrosion inhibitors and / or surface-active agents according to at least one feature of claims 9 or 10.