Ink was hurled at Patil by the agitators demanding Scheduled Tribe (ST) status for the Dhangar (shepherd) community. He was rushed to hospital in Pune immediately. The extent of injury wasn't immediately clear.
The incident took place at Bhigwan, in his assembly constituency of Indapur in Pune district, on Friday morning.
The agitators earlier last week torched state transport buses and also damaged public and private property in many parts of the state.