Mixer and mixing method of mixing polymer dope, and solution casting apparatus and process

A mixing method of mixing liquid additive with polymer dope constituted by polymer and solvent, comprising steps of:

• ejecting said liquid additive through a supply conduit into said polymer dope in a mixing conduit;
• and
• mixing said liquid additive with said polymer dope by use of a rotor hub positioned downstream from said supply conduit, contained in said mixing conduit, having a diameter decreasing end on an upstream side, and rotated by electromagnetic induction about an axis directed in a flow direction of said polymer dope,
• wherein a surface of said rotor hub is supported by a support disposed within said mixing conduit, and
• said rotor hub is driven to rotate at such a peripheral speed V3 as to set a Reynolds value Re higher than 0.02, where said Reynolds value Re is defined by an equation of:
• Re=Δd·V3·ρk/ηk
• where ηk is viscosity of said polymer dope supplied with said liquid additive;
• ρk is density of said polymer dope;
• Δd is a size of a gap between an inside of said mixing conduit and a peripheral surface of said rotor hub.