Lubricant for oil retaining bearing

Abstract

A lubricant for an oil retaining bearing containing 1 to 100% by mass of an ionic liquid. The lubricant has a low vapor pressure, low flammability, excellent heat resistance and ability to suppress the emanation of low volatile components and decomposed gases during use, or a lubricant for an oil retaining bearing which has antistatic property and is capable of grounding the static electricity generated by flow charging of the lubricant.

1 . A lubricant for an oil retaining bearing comprising 1 to 100% by mass of an ionic liquid. 
   
   
       2 . A lubricant for an oil retaining bearing as defined in  claim 1 , comprising a base oil which contains 50 to 100% by mass of the ionic liquid. 
   
   
       3 . A lubricant for an oil retaining bearing as defined in  claim 2 , wherein the ionic liquid contained in the base oil has a pour point of 0° C. or below. 
   
   
       4 . A lubricant for an oil retaining bearing as defined in  claim 1 , wherein the ionic liquid is contained as an antistatic agent. 
   
   
       5 . A lubricant for an oil retaining bearing as defined in any one of  claims 1  to  4 , which has a volume resistivity at 25° C. of 1×10 10 Ω·cm or less. 
   
   
       6 . A lubricant for an oil retaining bearing as defined in any one of  claims 1  to  5 , wherein the ionic liquid is a compound represented by the following general formula (I):
   (Z p+ ) k .(A q− ) m   (I)   
     (where Z p+  represents a cation, A q−  represents an anion, p, q, k, m, p×k and q×m are each an integer of 1 to 3, with the proviso that p×k equals q×m and that, when k or m is 2 or more, Z or A may be the same or different, respectively.) 
   
   
       7 . A lubricant for an oil retaining bearing as defined in  claim 6 , wherein p, q, k and m in the general formula (I) are each 1. 
   
   
       8 . A lubricant for an oil retaining bearing as defined in any one of  claims 1  to  5 , wherein the ionic liquid is of a zwitter ion type in which the cation and the anion are bonded by a covalent bond. 
   
   
       9 . A lubricant for an oil retaining bearing as defined in any one of  claims 6  to  8 , wherein the ionic liquid has a cation in which a nitrogen atom is the ionic center. 
   
   
       10 . A lubricant for an oil retaining bearing as defined in any one of  claims 1  to  9 , which has a kinematic viscosity of 1 to 1,000 mm 2 /s at a temperature of 40° C. 
   
   
       11 . A lubricant for an oil retaining bearing as defined in any one of  claims 1  to  10 , which is retained in the bearing of a metal porous body, a plastic porous body or a ceramic porous body. 
   
   
       12 . An oil retaining bearing using a lubricant for an oil retaining bearing as defined in any one of  claims 1  to  11 . 
   
   
       13 . A motor unit comprising an oil retaining bearing as defined in  claim 12 .