Lubricating base oil blend

Abstract

The present invention relates to a lubricating base oil blend comprising (a) a mineral oil derived base oil having a saturates content of more than 90 wt %, a sulphur content of less than 0.03 wt % and a viscosity index of between 80-150, and (b) a paraffinic base oil component having a viscosity at 1000 C of from 7 to 30 cSt (7 to 30 mm2/s), wherein component (b) is an isomerised Fischer-Tropsch derived bottoms product having a ratio of percentage of recurring methylene carbons which are four or more carbons removed from an end group and a branch to the percentage of isopropyl carbon atoms, as determined by 13C-NMR, of below 8.2.

1 . A lubricating base oil blend comprising
 (a) a mineral oil derived base oil having a saturates content of more than 90 wt %, a sulphur content of less than 0.03 wt % and a viscosity index of between 80-150, and   (b) a paraffinic base oil component having a viscosity at 100° C. of from 7 to 30 cSt (7 to 30 mm 2 /s), wherein component (b) is an isomerised Fischer-Tropsch derived bottoms product having a ratio of percentage of recurring methylene carbons which are four or more carbons removed from an end group and a branch to the percentage of isopropyl carbon atoms, as determined by  13 C-NMR, of below 8.2.   
     
     
         2 . A base oil blend according to  claim 1 , wherein the mineral derived base oil component (a) is present in an amount of from 40 wt % to 95 wt %, based on the total weight of the oil blend. 
     
     
         3 . A base oil blend according to  claim 1  wherein the blend has a kinematic viscosity at 100° C. of greater than 12.0 cSt and a viscosity index of greater than 95. 
     
     
         4 . A base oil blend according to  claim 1 , wherein the viscosity index of component (a) is between 100 and 110. 
     
     
         5 . A base oil blend according to  claim 1 , wherein the cloud point of the blend has a value of below 0° C. 
     
     
         6 . A base oil blend according to  claim 1 , wherein the base oil component (a) is an API Group II and/or an API Group III base oils as defined in API Publication 1509. 
     
     
         7 . A base oil blend according to  claim 1 , wherein component (b) has a pour point of below −28° C. 
     
     
         8 . A process for the preparation of a lubricant base oil blend, comprising blending
 a) a mineral oil derived base oil having a saturates content of more than 90 wt %, a sulphur content of less than 0.03 wt % and a viscosity index of between 80-150, and   b) a paraffinic base oil component having a viscosity at 100° C. of from 7 to 30 cSt (7 to 30 mm 2 /s), wherein component (b) is an isomerised Fischer-Tropsch derived bottoms product having a ratio of percentage of recurring methylene carbons which are four or more carbons removed from an end group and a branch to the percentage of isopropyl carbon atoms, as determined by  13 C-NMR, of below 8.2.   
     
     
         9 . The process according to  claim 8 , wherein component (b) has an average degree of branching in the molecules of above 10 alkyl branches per 100 carbon atoms. 
     
     
         10 . The process according to  claim 8 , wherein the paraffinic base oil component (b) is a heavy bottom heavy bottom distillate fraction obtained from a Fischer-Tropsch derived wax or waxy raffinate feed by:
 (a) hydrocracking/hydroisomerisating a Fischer-Tropsch derived feed, wherein weight ratio of compounds having at least 60 or more carbon atoms and compounds having at least 30 carbon atoms in the Fischer-Tropsch derived feed is at least 0.2 and wherein at least 30 wt % of compounds in the Fischer-Tropsch derived feed have at least 30 carbon atoms;   (b) separating the product of step (a) into one or more distillate fraction(s) of lower boiling fractions and a broad range base oil precursor fraction and a heavy fraction such that the T90 wt % boiling point of the base oil precursor fraction is between 350 and 550° C.;   (c) performing a pour point reducing step to the broad range base oil precursor fraction obtained in step (b); and   (d) isolating the heavy bottom distillate fraction by distilling the product of step (c).