Resin extruder , rotor-type screw shaped so that the size of the gap between the screw and the inner surface of the cylinder holding the screw changes, and resin manufacturing method

A rotor-type screw for an extruder that kneads a resin, wherein

• top and bottom parts of a flight are formed in such a way that gaps between the top and bottom parts and an inner surface of a cylinder are changed from a front point to a rear point of the rotor-type screw in a rotation direction in a cross section that is vertical to an axial direction,
• the top and bottom parts of the flight are disposed opposite to each other with respect to an axis line,
• the top part is twisted in a spiral shape with respect to the axis line,
• the top and bottom parts of the flight are formed in such a way that the size of each gap is increased from the front point to the rear point of the rotor-type screw in the cross section that is vertical to the axial direction,
• the size of the gap at the front point is equal to or smaller than 1/10 of the diameter of the cylinder, and
• a lead of each flight is four or more times larger than the diameter of the cylinder.

A resin manufacturing method comprising:

• rotating a rotor-type screw that is disposed in a cylinder and in which top and bottom parts of a flight are formed in such a way that the size of each gap between the top and bottom parts and an inner surface of the cylinder is increased from a front point to a rear point of the rotor-type screw in a rotation direction in a cross section that is vertical to an axial direction;
• and
• elongating a resin material that is present in the gap from the front to the rear in the rotation direction,
• wherein the top and bottom parts of the flight are disposed opposite to each other with respect to an axis line,
• the top part is twisted in a spiral shape with respect to the axis line,
• the size of the gap at the front point is equal to or smaller than 1/10 of the diameter of the cylinder, and
• a lead of each flight is four or more times larger than the diameter of the cylinder.