Use alkali and/or triethanolamine salts of the alkanoylamidocarboxylic acids in metal working

Abstract

At least 5, preferably at least 30, in particular about 50, percent by weight of the alkali metal salts and/or triethanolamine salts of alkanoylamidocarboxylic acids of the general formula ##STR1## R.sup.1 denotes an alkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbon atoms, ##STR2## R.sup.4 denotes a hydrogen atom; m is 2;n is 0 or 1, andz denotes an integer from 0 to 3;are used as antifoams in corrosion-inhibiting metal working compositions.

Description

The invention relates to alkali metal salts and triethanolamine salts of alkanoylamidocarboxylic acids, as have been disclosed as metal working compositions in AT 344 854 B. According to said publication, such salts have been used to date as corrosion-inhibiting coolants and metal working compositions. Most salts stated there gave good to very good corrosion protection in the machining of the workpieces. However, they exhibit undesirably strong foaming in modern high-speed metal working centres, owing to the large cooling lubricant circulation and the high delivery pressure. The addition of commercial antifoams results in only a partial improvement and in particular only briefly, and on the other hand occasionally gives rise to undesired side effects.

It is therefore the object of the invention to select those salts which exhibit a continuously low level of foaming behaviour which meets the requirements of modern NC machines. This is achieved in a surprising manner by alkali metal salts and/or triethanolamine salts of alkanoylamidocarboxylic acids of the general formula (A) ##STR3## in which R.sup.1 denotes an alkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbon atoms;

R.sup.2 denotes the radical ##STR4## R.sup.3 denotes the radical R.sup.2 or ##STR5## R.sup.4 denotes a hydrogen atom or an alkane radical having 1 to 3 carbon atoms; m is 2 n is 0 or 1, and z denotes an integer form 0-3 in an amount of at least 5, preferably at least 30, in particular 50, percent by weight of the concentrate of corrosion-inhibiting metal working compositions in aqueous solution, as antifoams.

They include virtually exclusively salts of monoalkanoylethylenediaminetriacetic or monoalkanoylethylenediaminetripropionic acids, monoalkanoyldiethylenetriaminetetraacetic or monoalkanoyldiethylenetriaminetetrapropionic acids, monoalkanoyltriethylenetetraminepentaacetic or monoalkanoyltriethylenetetraminepentapropionic acids or monoalkanoyltetraethylenepentaminehexaacetic or monoalkanoyltetraethylenepentaminehexapropionic acids, i.e.:

1. N-caproylethylenediamine-N,N',N'-triacetic acid 2. N-caproylethylenediamine-N,N',N'-tripropionic acid 3. N-isooctanoylethylenediamine-N,N',N'-triacetic acid 4. N-isooctanoylethylenediamine-N,N',N'-tripropionic acid 5. N-isononanoylethylenediamine-N,N',N'-triacetic acid 6. N-isononanoylethylenediamine-N,N',N'-tripropionic acid 7. N-isononanoyldiethylenetriamine-N,N',N",N"-tetraacetic acid 8. N-isononanoyldiethylenetriamine-N,N',N",N"-tetrapropionic acid 9. N-decanoylethylenediamine-N,N',N'-triacetic acid 10. N-decanoylethylenediamine-N,N',N'-tripropionic acid 11. N-undecanoylethylenediamine-N,N',N'-triacetic acid 12. N-undecanoylethylenediamine-N,N',N'-tripropionic acid

In 2% aqueous solution, salts of these acids give such low-foam cooling lubricants that they no longer give rise to any troublesome foam development even with the largest cooling lubricant circulation and delivery pressures up to 20 bar.

The foam behaviour of the above-mentioned compounds was now tested by the perforated-disc beating method according to DIN 53902, Part 1, compounds of the Austrian Patent mentioned at the outset, namely the triethanolamine salts of N,N'-diisononanoylethylenediamine-N,N'-diacetic acid (A) or of N,N'-diisononanoylethylenediamine-N,N'-dipropionic acid (B), exhibiting very disadvantageous foaming behaviour.

TABLE 1__________________________________________________________________________Triethanol- Foam height Foam height Foam height Foam heightamine salt of Concentration (in mm) immediately (in mm) (in mm) (in mm)compound No. (in % by weight) after beating after 10 sec after 20 sec after 30 sec__________________________________________________________________________Blank distilled 10 0 0 0sample waterA 2% 100 70 58 40B 2% 105 72 60 411 2% 13 2 0 02 2% 15 1 0 03 2% 15 2 0 04 2% 15 1 0 05 2% 15 2 0 06 2% 15 2 0 07 2% 12 0 0 08 2% 13 0 0 09 2% 16 3 0 010 2% 16 2 0 011 2% 17 4 0 012 2% 17 4 0 0__________________________________________________________________________

As shown in Table 1, for example A gave a foam height of 100 mm immediately after beating, which was still 70 mm after 10 sec, 58 mm after 20 sec and declined to 7 mm only after 180 sec. In contrast, the compounds according to the invention exhibited a substantially more advantageous foam behaviour.

Interestingly, the foam effect of other salts, in particular of those salts protected in the Austrian Patent mentioned at the outset, but also of those other, conventional, water-miscible cooling lubricants and metal working compositions, for example also of oil emulsions, is greatly reduced merely by adding small amounts of only 5 to 40, preferably 10 to 30, % by weight of the compounds according to the invention. With additions of 50% or more, the foam effect is already virtually just as small as in the case of the pure substances according to the invention.

The foam behaviour of mixtures of the triethanolamine salts of the acids according to the invention with other cooling lubricants, such as, for example, A or B from the AT-patent mentioned at the outset, or with Syntelo.RTM. (from Castrol) or a mineral oil emulsion Mobilmet.RTM. 151 (containing phosphoric esters and alkanolamine esters of boric acid), is shown in Table 2 below.

TABLE 2__________________________________________________________________________Foam height (in mm) after beating:Triethanol-amine salts ofcompound No.as a mixture with Concentration Immediately after after after after after afterin the ratio (% by weight) after beating 10 sec 20 sec 30 sec 60 sec 120 sec 180 sec__________________________________________________________________________for comp.:A 2% 100 70 58 40 26 12 7for comp.:B 2% 105 72 60 41 26 13 8No. 6:A = 30:70 2 50 40 22 15 4 0 0No. 6:A = 50:50 2 15 10 5 0 0 0 0No. 6:A = 60:40 2 15 7 0 0 0 0 0No. 7:B = 30:70 2 40 28 16 7 0 0 0No. 7:B = 50:50 2 15 10 0 0 0 0 0No. 7:B = 60:40 2 13 3 0 0 0 0 0 immediately after after after after after after after beating 60 sec 120 sec 180 sec 4 min 8 min 15 minC (Mobilmet .RTM.) 3 250 200 180 150 120 50 10No. 6:C = 17:83 3.6 170 120 100 80 30 6 0No. 6:C = 25:75 4 120 85 40 18 0 0 0No. 6:C = 33:67 4.5 100 65 22 7 0 0 0No. 7:C = 17:83 3.6 160 100 90 70 20 0 0No. 7:C = 25:75 4 110 70 40 15 0 0 0No. 7:C = 33:67 4.5 100 48 12 0 0 0 0__________________________________________________________________________

Claims

1. A method to reduce foaming of corrosion-inhibiting metal working compositions, comprising the steps of

selecting at least one of alkali metal salts and triethanolamine salts of alkanoylamidocarboxylic acids of a general formula ##STR6## R.sup.1 denoted an alkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbon atoms,

R.sup.2 denotes the radical ##STR7## R.sup.3 denotes the radical --R.sup.2 or ##STR8## R.sup.4 denotes a hydrogen atom; m is 2

n is 0 or 1

z denotes an integer form 0 to 3, and

adding an amount of at least 5 percent by weight to a concentrate of said corrosion-inhibiting metal working compositions in aqueous solution, as antifoams.

2. The method according to claim 1, characterized in that salts of monoalkanoylethylenediaminetriacetic or monoalkanoylethylenediaminetripropionic acids, monoalkanoyldiethylenetriaminetetraacetic or monoalkanoyldiethylenetriaminetetrapropionic acids, monoalkanoyltriethylenetetraminepentaacetic or monoalkanoyltriethylenetetraminepentapropionic acids or monoalkanoyltetraethylenepentaminehexaacetic or monoalkanoyltetraethylenepentaminehexapropionic acids, in particular of one of the following acids, are used:

N-caproylethylenediamine-N,N',N'-triacetic acid

N-caproylethylenediamine-N,N',N'-tripropionic acid

N-isooctanoylethylenediamine-N,N',N'-triacetic acid

N-isooctanoylethylenediamine-N,N',N'-tripropionic acid

N-isononanoylethylenediamine-N,N',N'-triacetic acid

N-isononanoylethylenediamine-N,N',N'-tripropionic acid

N-isononanoyldiethylenetriamine-N,N',N",N"-tetraacetic acid

N-isononanoyldiethylenetriamine-N,N',N",N"-tetrapropionic acid

N-decanoylethylenediamine-N,N',N'-triacetic acid

N-decanoylethylenediamine-N,N',N'-tripropionic acid

N-undecanoylethylenediamine-N,N',N'-triacetic acid

N-undecanoylethylenediamine-N,N',N'-tripropionic acid.

3.

3. Water-miscible, mineral oil-containing cooling lubricants and metal working compositions, containing 5 to 40 percent by weight of at least one of alkali metal salts and triethanolamine salts of alkanoylamidocarboxylic acid of a general formula ##STR9## R.sup.1 denoted an alkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbon atoms,

R.sup.2 denotes the radical ##STR10## R.sup.3 denotes the radical --R.sup.2 or ##STR11## R.sup.4 denotes a hydrogen atom; m is 2

n is 0 or 1

z denotes an integer form 0 to 3

in an amount of at least 5 percent by weight of a concentrate of corrosion-inhibiting metal working compositions in aqueous solution, as antifoams.

4. The method according to claim 1, wherein said antifoams are added in an amount of at least 30 percent by weight of a concentrate of corrosion-inhibiting metal working compositions in aqueous solution.

5. The method according to claim 1, wherein said antifoams are added in an amount of at least 50 percent by weight of the concentrate of corrosion-inhibiting metal working compositions in aqueous solution.

6. The water-miscible, mineral oil-containing cooling lubricants and metal working compositions according to claim 3, containing 10 to 30 percent by weight of said salts.