Patent Publication Number: US-6040281-A

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

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 1  denotes an alkanoyl or an alkanesulfonyl radical, each having 6 to 20 carbon atoms; 
     R 2  denotes the radical ##STR4## R 3  denotes the radical R 2  or ##STR5## R 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&#39;,N&#39;-triacetic acid 
     2. N-caproylethylenediamine-N,N&#39;,N&#39;-tripropionic acid 
     3. N-isooctanoylethylenediamine-N,N&#39;,N&#39;-triacetic acid 
     4. N-isooctanoylethylenediamine-N,N&#39;,N&#39;-tripropionic acid 
     5. N-isononanoylethylenediamine-N,N&#39;,N&#39;-triacetic acid 
     6. N-isononanoylethylenediamine-N,N&#39;,N&#39;-tripropionic acid 
     7. N-isononanoyldiethylenetriamine-N,N&#39;,N&#34;,N&#34;-tetraacetic acid 
     8. N-isononanoyldiethylenetriamine-N,N&#39;,N&#34;,N&#34;-tetrapropionic acid 
     9. N-decanoylethylenediamine-N,N&#39;,N&#39;-triacetic acid 
     10. N-decanoylethylenediamine-N,N&#39;,N&#39;-tripropionic acid 
     11. N-undecanoylethylenediamine-N,N&#39;,N&#39;-triacetic acid 
     12. N-undecanoylethylenediamine-N,N&#39;,N&#39;-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&#39;-diisononanoylethylenediamine-N,N&#39;-diacetic acid (A) or of N,N&#39;-diisononanoylethylenediamine-N,N&#39;-dipropionic acid (B), exhibiting very disadvantageous foaming behaviour. 
     
                                           TABLE 1                                 
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Triethanol-    Foam height                                                
                         Foam height                                      
                               Foam height                                
                                     Foam height                          
amine 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                         
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Blank  distilled                                                          
               10        0     0     0                                    
sample water                                                              
A      2%      100       70    58    40                                   
B      2%      105       72    60    41                                   
1      2%      13        2     0     0                                    
2      2%      15        1     0     0                                    
3      2%      15        2     0     0                                    
4      2%      15        1     0     0                                    
5      2%      15        2     0     0                                    
6      2%      15        2     0     0                                    
7      2%      12        0     0     0                                    
8      2%      13        0     0     0                                    
9      2%      16        3     0     0                                    
10     2%      16        2     0     0                                    
11     2%      17        4     0     0                                    
12     2%      17        4     0     0                                    
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     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® (from Castrol) or a mineral oil emulsion Mobilmet® 151 (containing phosphoric esters and alkanolamine esters of boric acid), is shown in Table 2 below. 
     
                                           TABLE 2                                 
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Foam height (in mm) after beating:                                        
Triethanol-                                                               
amine salts of                                                            
compound No.                                                              
as a mixture with                                                         
        Concentration                                                     
               Immediately                                                
                     after                                                
                         after                                            
                             after                                        
                                 after                                    
                                     after                                
                                         after                            
in the ratio                                                              
        (% by weight)                                                     
               after beating                                              
                     10 sec                                               
                         20 sec                                           
                             30 sec                                       
                                 60 sec                                   
                                     120 sec                              
                                         180 sec                          
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for comp.:A                                                               
        2%     100   70  58  40  26  12  7                                
for comp.:B                                                               
        2%     105   72  60  41  26  13  8                                
No. 6:A = 30:70                                                           
        2      50    40  22  15  4   0   0                                
No. 6:A = 50:50                                                           
        2      15    10  5   0   0   0   0                                
No. 6:A = 60:40                                                           
        2      15    7   0   0   0   0   0                                
No. 7:B = 30:70                                                           
        2      40    28  16  7   0   0   0                                
No. 7:B = 50:50                                                           
        2      15    10  0   0   0   0   0                                
No. 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 min                           
C (Mobilmet ®)                                                        
        3      250   200 180 150 120 50  10                               
No. 6:C = 17:83                                                           
        3.6    170   120 100 80  30  6   0                                
No. 6:C = 25:75                                                           
        4      120   85  40  18  0   0   0                                
No. 6:C = 33:67                                                           
        4.5    100   65  22  7   0   0   0                                
No. 7:C = 17:83                                                           
        3.6    160   100 90  70  20  0   0                                
No. 7:C = 25:75                                                           
        4      110   70  40  15  0   0   0                                
No. 7:C = 33:67                                                           
        4.5    100   48  12  0   0   0   0                                
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