Water-soluble metalworking fluid, and metalworking coolant

Abstract

A water-soluble metalworking fluid of the invention contains: a component (A) that is a dicarboxylic acid including a sulfide structure; a component (B) that is a polyalkylene glycol; a component (C) that is polyhydric alcohol polyalkylene oxide adducts; and a component (D) that is a monocarboxylic acid.

1 . A water-soluble metalworking fluid comprising:
 a component (A) that is a dicarboxylic acid comprising a sulfide structure;   a component (B) that is a polyalkylene glycol;   a component (C) that is a polyhydric alcohol polyalkylene oxide adduct; and   a component (D) that is a monocarboxylic acid.   
     
     
         2 . The water-soluble metalworking fluid according to  claim 1 , wherein
 the component (A) is a compound represented by a formula (1),
   HOOC—R 1 —S n —R 2 —COOH   (1)
 
   where: R 1  and R 2  are each independently a hydrocarbon group having 1 to 5 carbon atoms, and   n is an integer from 1 to 8.   
     
     
         3 . The water-soluble metalworking fluid according to  claim 1 , wherein
 a content of the component (A) is in a range from 0.1 mass % to 14 mass %, based on a total amount of the fluid.   
     
     
         4 . The water-soluble metalworking fluid according to  claim 1 , wherein
 the component (B) is at least one selected from the group consisting of a compound represented by a formula (2) and a compound represented by a formula (3),
   HO—(EO) a -(PO) b -(EO) c -H   (2)
 
   where: EO denotes an ethylene oxide unit and PO denotes a propylene oxide unit,   a and c each independently are an integer from 1 to 30, and   b is an integer from 5 to 100,
   R 3 O—(R′O) d -H   (3)
 
   where: R 3  is an alkyl group having 1 to 30 carbon atoms,   R′O denotes an oxide unit selected from the group consisting of PO and EO, in which PO and EO are optionally used in mixture,   a mole fraction of EO in R′O is less than 1, and   d is an integer from 1 to 50.   
     
     
         5 . The water-soluble metalworking fluid according to  claim 1 , wherein
 a content of the component (B) is in a range from 10 mass % to 60 mass %, based on a total amount of the fluid.   
     
     
         6 . The water-soluble metalworking fluid according to  claim 1 , wherein
 the component (C) is at least one selected from the group consisting of compounds represented by formulae (4) to (7),   
       
         
           
           
               
               
           
         
         where: R 11  to R 14  are each independently an alkylene group having 1 to 5 carbon atoms, and e to h are each independently an integer from 1 to 30, 
       
       
         
           
           
               
               
           
         
         where: R 4  is an alkyl group having 1 to 30 carbon atoms, 
         R 21  to R 23  are each independently an alkylene group having 1 to 5 carbon atoms, and i to k are each independently an integer of 1 to 30, 
       
       
         
           
           
               
               
           
         
         where: R 5  and R 6  are each independently an alkyl group having 1 to 30 carbon atoms, 
         R 31  and R 32  are each independently an alkylene group having 1 to 5 carbon atoms, and 1 to m are each independently an integer from 1 to 30, 
       
       
         
           
           
               
               
           
         
         where: R 7  to R 9  are each independently an alkyl group having 1 to 30 carbon atoms, 
         R 41  is an alkylene group having 1 to 5 carbon atoms, and 
         n is an integer from 1 to 30. 
       
     
     
         7 . The water-soluble metalworking fluid according to  claim 1 , wherein
 a content of the component (C) is in a range from 5 mass % to 30 mass %, based on a total amount of the fluid.   
     
     
         8 . The water-soluble metalworking fluid according to  claim 1 , wherein
 the component (D) is a compound represented by a formula (8),
   R 10 —COOH   (8)
 
   where: R 10  is a hydrocarbon group having 11 or more carbon atoms.   
     
     
         9 . The water-soluble metalworking fluid according to  claim 1 , wherein
 a content of the component (D) is in a range from 1 mass % to 20 mass %, based on a total amount of the fluid.   
     
     
         10 . The water-soluble metalworking fluid according to  claim 1 , further comprising:
 a component (E) that is an acetylene glycol surfactant.   
     
     
         11 . The water-soluble metalworking fluid according to  claim 10 , wherein
 the component (E) is an acetylene glycol ethylene oxide adduct.   
     
     
         12 . The water-soluble metalworking fluid according to  claim 10 , wherein
 a content of the component (E) is in a range from 1 mass % to 15 mass %, based on a of the total amount of the fluid.   
     
     
         13 . The water-based metalworking fluid according to  claim 1 , wherein
 the water-based metalworking fluid is in a form of an undiluted solution comprising water in a range from 15 mass % to 75 mass %.   
     
     
         14 . A metalworking coolant obtained by diluting the water-based metalworking fluid according to  claim 1  with water by 2 to 200 times in volume. 
     
     
         15 . The metalworking coolant according to  claim 14 , wherein
 the metalworking coolant is suitable for use in grinding.