Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1997-08-27
1999-01-12
Green, Anthony
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
106 13, 106 1413, 106 1418, 106 1442, 106 1444, 252 70, 134 3, 134 41, 510254, 510255, 510258, 510264, C23G 124, C09K 318
Patent
active
058589473
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the use of a compound. In particular, the present invention relates to the use of ethylene diaminedisuccinic acid "EDDS".
2. Description of Related Art
In some applications it is desirable to clean metal surfaces, such as in the automotive and aeronautical industries, and in applications such as metal machining and forming, as well as in the preparation of circuit boards and integrated circuits.
Many of the metal cleaning compositions used contain, as their active agents, acids. However, whilst the acids may remove the external layers of dirt, grease, unwanted paint and the like, they can remove some or all of the protective metal oxide layers and, in doing so, make the cleaned metal more prone to corrosion. This is very undesirable.
There is therefore a need to have a metal cleaner that is non-corrosive, i.e. will not remove the metal's protective oxide layer (see for example Business Communications Company Inc. Report C.173 page 20, June 1993).
Generally, the corrosiveness of a solution can be measured in terms of anodic breakdown potential (mV) of the metal oxide layer. The higher the anodic breakdown potential (ABDP), the less the metal will corrode during and after treatment with the metal cleaner.
Ideally, metal cleaners should have ABDP values of at least 200 mV. Preferably, for the cleaning of aluminum it is desirable that the metal cleaners should have ABDP values of at least 400 mV.
Two of the commonly used metal cleaners are ethylene diamine tetra-acetic acid (EDTA) and gluconic acid (GA). However, there are problems associated with these metal cleaners. In this regard, under certain conditions EDTA has an ABDP value of 0 mV for aluminum and copper, two metals which are often in need of cleaning; whereas gluconic acid has an ABDP value of 0 mV for zinc, copper and aluminum.
Further ABDP values for these two metal cleaners are presented later in Tables 1-3.
There is therefore a need for metal cleaners that are not corrosive, i.e. have a low-corrosive effect on the metals.
The present invention seeks to overcome the problems associated with the prior art metal cleaners.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a metal cleaning composition comprising as its active agent at least EDDS.
According to a second aspect of the present invention there is provided a process of cleaning metal wherein the metal is cleaned with the composition as defined above.
According to a third aspect of the present invention there is provided the use of EDDS as a low-corrosive cleaning agent in a metal cleaning composition.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 discloses EDDS;
FIG. 2 illustrates the concentration of A1 (III) in 5% ligand solution, after exposure to aluminum foil for 24 hours at pH 7 and 25.degree. C.;
FIG. 3 illustrates the concentration of A1 (III) in 5% ligand solution, after exposure to aluminum foil for 24 hours at pH 10 and 25.degree. C.;
FIG. 4 illustrates the concentration of Cu(II) in 5% ligand solution, after exposure to copper oxide solid for 24 hours at pH 7 and 25.degree. C.;
FIG. 5 illustrates the concentration of Cu (II) in 5% ligand solution, after exposure to copper (II) oxide solid for 24 hours at pH 10 and 25.degree. C.;
FIG. 6 illustrates the concentration of Fe (III) in 5% ligand solution, after exposure to iron (III) oxide solid for 24 hours at pH 7 and 25.degree. C.;
FIG. 7 illustrates the concentration of metal in 5% (s,s)EDDS solution, after exposure to mixed metal oxides for 24 hours at pH 10 and 25.degree. C.;
FIG. 8 illustrates the concentration of metal in 5% EDTA solution, after exposure to mixed metal oxides for 24 hours at pH 10 and 25.degree. C.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The term "EDDS" includes racemic EDDS as well as optical isomers thereof, such as (s,s)EDDS, and active salts and active derivatives thereof. Preferably the term means (s,s)EDDS or salts thereof. Preferably the EDDS is (s,s)EDDS. More prefe
REFERENCES:
patent: 3158635 (1964-11-01), Kezerian et al.
patent: 4704233 (1987-11-01), Hartman et al.
JAPIO Patent Abstract No. JP409049084A which is an abstract of Japanese Patent Abstact No. 9-049084 (Feb. 1997.)
Brewer Mark L.
Duncan Andrew C.
MacMillan John A.
Green Anthony
The Associated Octel Company Limited
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