Functional fluid and the use thereof

A functional fluid comprising

• A) 5 to 30% by weight based on the total weight of the functional fluid of one or more alkyl(meth)acrylate polymers obtainable by polymerizing a mixture of olefinically unsaturated monomers, which comprises
• a) 15-70 wt % based on the total weight of the ethylenically unsaturated monomers of one or more ethylenically unsaturated ester compounds of formula (I)
• where R is hydrogen or methyl, R1 means a linear or branched alkyl residue with 1-6 carbon atoms, R2 and R3 independently represent hydrogen or a group of the formula —COOR′, where R′ means hydrogen or an alkyl group with 1-6 carbon atoms,
• b) 30-85 wt % based on the total weight of the ethylenically unsaturated monomers of one or more ethylenically unsaturated ester compounds of formula (II)
• where R is hydrogen or methyl, R4 means a linear or branched alkyl residue with 7-40 carbon atoms, R5 and R6 independently are hydrogen or a group of the formula —COOR″, where R″ means hydrogen or an alkyl group with 7-40 carbon atoms, and
• c) 0-50 wt % based on the total weight of the ethylenically unsaturated monomers of one or more comonomers, and
• B) 70 to 95% by weight based on the total weight of the functional fluid of at least one oxygen containing compound selected from the group consisting of neopentyl glycol dioleate, neopentyl glycol tallate, diethylene glycol dioleate, diethylene glycol tallate, propylene glycol tallate, trimethylol propane dioleate, pentaerythritol oleate, pentaerythritol dioleate and propylene glycol dioleate,
• wherein the functional fluid can achieve a Factory Mutual 6390 Group 1 or Group 2 rating.