Patent ID: 6858681

Claim:
A process for producing an olefinic polymer, the process comprising using a fluidized-bed reactor provided with a gas distributing plate having a large number of gas through-holes on the lower portion of a cylinder section, allowing gas containing at least polymerizable monomers to pass through the reactor by blowing the gas supplied to a gas introducing zone disposed below the gas distributing plate in the inside of the fluidized-bed reactor, through the gas distributing plate and by discharging the gas from the upper portion of the reactor and putting solid particles in a fluidized state by this gas flow, to (co)polymerize one or two or more olefins in a vapor phase, wherein; a saturated aliphatic hydrocarbon is introduced into said fluidized-bed in a liquid phase state and a vapor phase state; and the monomers are (co)polymerized in such a condition that when the inside radius of the cylinder section of the fluidized-bed reactor is defined as a distance of 1, the relationship between the concentration (C 1 ) of the saturated aliphatic hydrocarbon put in a liquid state in the peripheral portion of the cylinder section at a relative distance of 0.7 to 1.0 from the center of the cylinder section as a start point and the concentration (C 2 ) of the saturated aliphatic hydrocarbon put in a liquid state in the center portion of the cylinder section at a relative distance less than 0.7 from the center fulfills the following equation: C 1 >C 2 at a place does to the upstream section of said gas distributing plate.