The invention relates to a process for removal of volatile components from an olefin polymer, the process carried out in an extruder comprising at least one vacuum degassing zone, said process comprising the steps of: (a) introducing a stream of an olefin polymer into the extruder; (b) extruding the olefin polymer in the extruder at a temperature which is higher than the melting temperature of the olefin polymer but lower than the decomposition temperature of the olefin polymer, thereby producing an olefin polymer melt having reduced amount of volatile components, wherein the process in the extruder has a residence time distribution broadness (σ2) in the range of 800 to 4000 as define by equation (1) wherein: σ2 is the residence time distribution broadness, T is the mean residence time, t is the interval of residence time a fluid element of the olefin polymer spends in the extruder, E(t) is the residence time distribution function, and wherein the process optionally comprises a step (c) where the melt of the olefin polymer is passed through a die zone to a pelletizer for pelletizing the obtained olefin polymer.
σ.sup.2=∫.sub.0.sup.∞(t−τ).sup.2E(t)dt  equation (1)

The invention relates to a process for removal of volatile components from an olefin polymer, the process carried out in an extruder comprising at least one vacuum degassing zone, said process comprising the steps of: (a) introducing a stream of an olefin polymer into the extruder; (b) extruding the olefin polymer in the extruder at a temperature which is higher than the melting temperature of the olefin polymer but lower than the decomposition temperature of the olefin polymer, thereby producing an olefin polymer melt having reduced amount of volatile components, wherein the process in the extruder has a residence time distribution broadness (σ2) in the range of 800 to 4000 as define by equation (1) wherein: σ2 is the residence time distribution broadness, T is the mean residence time, t is the interval of residence time a fluid element of the olefin polymer spends in the extruder, E(t) is the residence time distribution function, and wherein the process optionally comprises a step (c) where the melt of the olefin polymer is passed through a die zone to a pelletizer for pelletizing the obtained olefin polymer.
σ.sup.2=∫.sub.0.sup.∞(t−τ).sup.2E(t)dt  equation (1)

A conveyance portion, a barrier portion, and a path are provided at places of a portion of a screw main body in which a kneading portion is provided. In at least one of the places, an entrance is opened to cause raw materials, conveyance of which is limited by a barrier portion to increase pressure on the raw materials, to flow in. The raw materials flowing in from the entrance flow through the path in the opposite direction to a conveyance direction of the conveyance portion. An exit is opened in an outer circumferential surface of the screw main body at a position outside the conveyance portion in which the entrance is opened.

An extruder screw includes a screw body. The screw body is rotated about an axis parallel to a direction of conveyance of a raw material. A conveyance portion having a flight is provided on the outer peripheral surface of the screw body. The flight is configured to convey the raw material along the axis of the screw body when the screw body is rotated. A passage for permitting the raw material fed by the flight to pass therethrough to the outer peripheral surface of the screw body is provided in the screw body in a position deviated from the axis of the screw body.

An extruder screw includes a screw body. The screw body is rotated about an axis parallel to a direction of conveyance of a raw material. A conveyance portion having a flight is provided on the outer peripheral surface of the screw body. The flight is configured to convey the raw material along the axis of the screw body when the screw body is rotated. A passage for permitting the raw material fed by the flight to pass therethrough to the outer peripheral surface of the screw body is provided in the screw body in a position deviated from the axis of the screw body.

An extruder includes a screw for extruder provided with a screw element for kneading a raw material, and a barrel including a cylinder portion in which the screw is inserted so as to be rotatable. A plurality of screw elements identical with the screw element are provided in a longitudinal direction of the screw under a certain rule. The barrel is integrated by combining a plurality of barrel blocks blocked. Each of the plurality of barrel blocks is configured in accordance with a length of the screw element provided in the longitudinal direction of the screw.

An extruder includes a screw for extruder provided with a screw element for kneading a raw material, and a barrel including a cylinder portion in which the screw is inserted so as to be rotatable. A plurality of screw elements identical with the screw element are provided in a longitudinal direction of the screw under a certain rule. The barrel is integrated by combining a plurality of barrel blocks blocked. Each of the plurality of barrel blocks is configured in accordance with a length of the screw element provided in the longitudinal direction of the screw.

A conveyance portion, a barrier portion, and a path are provided at places of a portion of a screw main body in which a kneading portion is provided. In at least one of the places, an entrance is opened to cause raw materials, conveyance of which is limited by a barrier portion to increase pressure on the raw materials, to flow in. The raw materials flowing in from the entrance flow through the path in the opposite direction to a conveyance direction of the conveyance portion. An exit is opened in an outer circumferential surface of the screw main body at a position outside the conveyance portion in which the entrance is opened.

An extruder screw includes a screw main body, conveyance portions, barrier portions, and paths. The raw materials, the conveyance of which is limited by the barrier portions, flow in from the entrance. The raw materials flowing in from the entrance flow through the paths in an opposite direction to a conveyance direction of the conveyance portions. The exit is opened in the outer circumferential surface of the screw main body at a position on an upstream side in the conveyance direction in the conveyance portions in which the entrance is opened.

The invention relates to a process for removal of volatile components from an olefin polymer, the process carried out in an extruder comprising at least one vacuum degassing zone, said process comprising the steps of: (a) introducing a stream of an olefin polymer into the extruder; (b) extruding the olefin polymer in the extruder at a temperature which is higher than the melting temperature of the olefin polymer but lower than the decomposition temperature of the olefin polymer, thereby producing an olefin polymer melt having reduced amount of volatile components, wherein the process in the extruder has a residence time distribution broadness (σ2) in the range of 800 to 4000 as define by equation (1) wherein: σ2 is the residence time distribution broadness, T is the mean residence time, t is the interval of residence time a fluid element of the olefin polymer spends in the extruder, E(t) is the residence time distribution function, and wherein the process optionally comprises a step (c) where the melt of the olefin polymer is passed through a die zone to a pelletizer for pelletizing the obtained olefin polymer.

σ.sup.2=∫.sub.0.sup.∞(t−τ).sup.2E(t)dt   equation (1)