Hydraulic lubricant formulations with high flash point and improved shear stability

A method for the preparation of a composition, the method comprising:

• (i) preparing a monomer mixture, comprising:
• (A) 5 wt. % to 80 wt. % of one or more solvent selected from the group consisting of tetrabutane and tetrabutene;
• (B) 20 wt. % to 95 wt. % of a polyalkyl (meth)acrylate comprising:
• (a) 5 wt. % to 25 wt. % of one or more C1-4 alkyl (meth)acrylates;
• (b) 75 wt. % to 95 wt. % of one or more linear or branched C8-15 alkyl (meth)acrylates;
• and
• (c) 0 wt. % to 0.5 wt. % of one or more linear or branched C16-20 alkyl (meth)acrylates,
• wherein the polyalkyl (meth)acrylate has a weight-average molecular weight in the range of 30,000 g/mol to 200,000 g/mol;
• and
• (C) optionally, a chain transfer agent;
• and
• (ii) charging 10 wt. % to 100 wt. % of the monomer mixture prepared under (i) to a reaction vessel to form a reaction mixture;
• (iii) heating the resulting reaction mixture to a desired reaction temperature;
• (iv-1) adding 0.1 wt. % to 0.5 wt. %, based on the total amount of monomers used, of a free radical initiator stepwise to the reaction mixture, or
• (iv-2) adding 0.1 wt. % to 0.5 wt. %, based on the total amount of monomers used, of a free radical initiator to the reaction mixture and 0.1 wt. % to 1.0 wt. %, based on the total amount of monomers used, to the monomer mixture prepared under (i);
• (v) feeding continuously 0 wt. % to 90 wt. % of the monomer mixture prepared under (i) to the reaction vessel;
• (vi) optionally, after a reaction time of at least 1 hour, adding 0.2 wt. %, based on the total amount of monomers used, of a further shot of the initiator;
• (vii) holding the reaction mixture prepared under (v) for another 1 to 5 hours;
• and
• (viii) optionally, further processing of the reaction mixture to receive the targeted composition.