Hydraulic fluids in plastic injection molding processes

Abstract

The present invention relates to the use of hydraulic fluids in plastic injection molding processes. Thereby it was surprisingly found that the use of hydraulic fluids with the right combination of physical parameters like the viscosity grade, the viscosity index, the density and the dispersancy allows for significant energy savings in plastic injection molding processes (PIM). The PIM process is an industrial process to manufacture plastic parts at well controlled temperatures, pressures and cycle times. The energy consumption of the process became more important over the last years, however, other parameters like process stability and accuracy of plastic part parameters as well as machine protection and long oil drain intervals have to be satisfying.

1 . A hydraulic fluid composition used for reducing the energy consumption of a hydraulic system, comprising a hydraulic fluid, in a plastic injection molding process, wherein the hydraulic fluid composition comprises
 (i) a polyalkyl(meth)acrylate viscosity index improver comprising monomer units of
 a) 5 to 40 wt. % of one or more ethylenically unsaturated ester compounds of formula (I) 
   
       
         
           
           
               
               
           
         
         
           wherein R is equal to H or CH 3 , 
           R 1  represents a linear or branched alkyl group with 1 to 6 carbon atoms, 
           R 2  and R 3  independently represent H or a group of the formula —COOR′, wherein R′ is H or an alkyl group with 1 to 5 carbon atoms, 
           b) 50 to 95 wt. % of one or more ethylenically unsaturated ester compounds of formula (II) 
         
       
       
         
           
           
               
               
           
         
         
           wherein R is equal to H or CH 3 , 
           R 4  represents a linear or branched alkyl group with 7 to 15 carbon atoms, 
           R 5  and R 6  independently represent H or a group of the formula —COOR″, wherein R″ is H or an alkyl group with 6 to 15 carbon atoms, 
           c) 0 to 30 wt. % of one or more ethylenically unsaturated ester compounds of formula (III) 
         
       
       
         
           
           
               
               
           
         
         
           wherein R is equal to H or CH 3 , 
           R 7  represents a linear or branched alkyl group with 16 to 30 carbon atoms, 
           R 8 and R 9  independently represent H or a group of the formula —COOR′″, wherein R′″ is H or an alkyl group with 16 to 30 carbon atoms, and 
           d) 0 to 10 wt. % of at least one N-dispersant monomer, and 
         
         (ii) a base oil selected from API group I, II, III or IV base oils or mixture thereof, 
         wherein the formulated hydraulic fluid has 
         a fresh oil viscosity index of at least 160, 
         a viscosity at 40° C. of 15 cSt to 51 cSt, 
         a density at 15° C. of 800 kg/m 3  to 890 kg/m 3 . 
       
     
     
         2 . The hydraulic fluid composition according to  claim 1 , wherein the industrial hydraulic application is a plastic injection molding process or is a process carried out in a hydraulic press. 
     
     
         3 . The hydraulic fluid composition according to  claim 1 , wherein the weight average molecular weight (M w ) of the polyalkyl(meth)acrylate viscosity index improver (i) is 20,000 to 100,000 g/mol. 
     
     
         4 . The hydraulic fluid composition according to  claim 3 , wherein the weight average molecular weight (M w ) of the polyalkyl(meth)acrylate viscosity index improver (i) is 40,000 to 70,000 g/mol. 
     
     
         5 . The hydraulic fluid composition according to  claim 1 , wherein the hydraulic fluid has a viscosity index of at least 180, a viscosity at 40° C. of equal or less than 36 cSt and a density at 15° C. of less than 860 kg/m 3 . 
     
     
         6 . The hydraulic fluid composition according to  claim 5 , wherein the hydraulic fluid has a viscosity index of at least 250, a viscosity at 40° C. between 19 cSt and 28 cSt and a density at 15° C. of less than 840 kg/m 3 . 
     
     
         7 . The hydraulic fluid composition according to  claim 1 , wherein said N-dispersant monomer is of the formula 
       
         
           
           
               
               
           
         
         wherein R 10 , R 11  and R 12  independently are H or an alkyl group with 1 to 5 carbon atoms and R 13  is either 
         a group C(Y)X—R 14    
         with X═O 
         or X═NH 
         and Y is (═O) or (═NR 15 ), where R 15  is an alkyl or aryl group, 
         and R 14  represents a linear or branched alkyl group with 1 to 20 carbon atoms which is substituted by a group NR 16 R 17  where R 16  and R 17  independently represent H or a linear or branched alkyl group with 1 to 8 carbon atoms, or wherein R 16  and R 17  are part of a 4 to 8 membered saturated or unsaturated ring containing optionally one or more hetero atoms chosen from the group consisting of nitrogen, oxygen or sulfur, wherein said ring may be further substituted with alkyl or aryl groups, 
         or 
         R 13  is a group NR 18 R 19 , wherein R 18  and R 19  are part of a 4 to 8 membered saturated or unsaturated ring, containing at least one carbon atom as part of the ring which forms a double bond to a hetero atom chosen from the group consisting of nitrogen, oxygen or sulfur, wherein said ring may be further substituted with alkyl or aryl groups. 
       
     
     
         8 . The hydraulic fluid composition according to  claim 7 , wherein said dispersant monomer e) of polymer (i) is at least one monomer selected from the group consisting of N-vinylic monomers, (meth)acrylic esters, (meth)acrylic amides, (meth)acrylic imides each with dispersing moieties in the side chain. 
     
     
         9 . The hydraulic fluid composition according to  claim 7 , wherein said N-dispersant monomer is at least one monomer selected from the group consisting of N-vinyl pyrrolidone, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminopropylmethacrylamide. 
     
     
         10 . The hydraulic fluid composition according to  claim 1 , wherein the polyalkyl(meth)acrylate viscosity index improver comprises a polydispersity index of between 1.5 and 2.5. 
     
     
         11 . The hydraulic fluid composition according to  claim 1 , wherein the polyalkyl(meth)acrylate viscosity index improver comprises monomer units of
 a) 5 to 20 wt. % of the compounds of formula (I),   b) 70 to 90 wt. % of the compound of formula (II), and   c) 5 to 25 wt. % of the compound of formula (III).   
     
     
         12 . The hydraulic fluid composition according to  claim 1 , wherein the hydraulic fluid composition comprises 70 to 95 wt. % of the base oil selected from API group I, II, III or IV base oils or mixture thereof and
 5 to 30 wt. % of the polyalkyl(meth)acrylate viscosity index improver.   
     
     
         13 . The hydraulic fluid composition according to  claim 12 , wherein the hydraulic fluid composition comprises
 80 to 95 wt. % of the base oil and   5 to 20 wt. % of the polyalkyl(meth)acrylate viscosity index improver.   
     
     
         14 . The hydraulic fluid composition according to  claim 1 , wherein the hydraulic fluid composition comprises a Dispersant-Inhibitor (DI) package, comprising antioxidants, antifoam agents, anticorrosion agents and/or at least one Phosphorous or Sulfur containing antiwear agent. 
     
     
         15 . The hydraulic fluid composition according to  claim 2 , wherein the weight average molecular weight (M w ) of the polyalkyl(meth)acrylate viscosity index improver (i) is 20,000 to 100,000 g/mol. 
     
     
         16 . The hydraulic fluid composition according to  claim 2 , wherein the hydraulic fluid has a viscosity index of at least 180, a viscosity at 40° C. of equal or less than 36 cSt and a density at 15° C. of less than 860 kg/m 3 . 
     
     
         17 . The hydraulic fluid composition according to  claim 2 , wherein said N-dispersant monomer is of the
 formula   
       
         
           
           
               
               
           
         
         wherein R 10 , R 11  and R 12  independently are H or an alkyl group with 1 to 5 carbon atoms and R 13  is either 
         a group C(Y)X—R 14    
         with X═O 
         or X═NH 
         and Y is (═O) or (═NR 15 ), where R 15  is an alkyl or aryl group, 
         and R 14  represents a linear or branched alkyl group with 1 to 20 carbon atoms which is substituted by a group NR 16 R 17  where R 16  and R 17  independently represent H or a linear or branched alkyl group with 1 to 8 carbon atoms, or wherein R 16  and R 17  are part of a 4 to 8 membered saturated or unsaturated ring containing optionally one or more hetero atoms chosen from the group consisting of nitrogen, oxygen or sulfur, wherein said ring may be further substituted with alkyl or aryl groups, 
         or 
         R 13  is a group NR 18 R 19 , wherein R 18  and R 19  are part of a 4 to 8 membered saturated or unsaturated ring, containing at least one carbon atom as part of the ring which forms a double bond to a hetero atom chosen from the group consisting of nitrogen, oxygen or sulfur, wherein said ring may be further substituted with alkyl or aryl groups. 
       
     
     
         18 . The hydraulic fluid composition according to  claim 8 , wherein said N-dispersant monomer is at least one monomer selected from the group consisting of N-vinyl pyrrolidone, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminopropylmethacrylamide. 
     
     
         19 . The hydraulic fluid composition according to  claim 2 , wherein the polyalkyl(meth)acrylate viscosity index improver comprises a polydispersity index of between 1.5 and 2.5. 
     
     
         20 . The hydraulic fluid composition according to  claim 2 , wherein the polyalkyl(meth)acrylate viscosity index improver comprises monomer units of
 a) 5 to 20 wt. % of the compounds of formula (I),   b) 70 to 90 wt. % of the compound of formula (II), and   c) 5 to 25 wt. % of the compound of formula (III).