Method and apparatus for producing dope and solution casting method
An additive is fed in a tube which is connected to a pipe for feeding a polymer solution, and a nozzle is provided in a front end of the tube. On a front end of the nozzle, a slit like slit is formed so as to extend in a diameter direction of the pipe. The front end is almost perpendicular to an upstream end of the nearest element of a static mixer. When the additive is added to the polymer solution through the slit, the additive is separated enough from a forward side of the static mixer, and the addition is made without rotation of the additive. Thus the mixing and stirring of the polymer solution and the additive is effectively made.
1 . A method of producing a dope comprising steps of:
dissolving a polymer to a, solvent, so as to obtain a polymer solution;
passing said polymer solution through a pipe;
adding to said polymer solution an additive through a slit disposed in said pipe, said slit extending in a diameter direction of said pipe; and
mixing and stirring a mixture of said polymer solution and said additive by an inline mixer, such that said dope may be obtained.
2 . A method as described in claim 1 , wherein a length of said slit is in the range of 20% to 80% of an inner diameter of said pipe.
3 . A method as described in claim 1 , wherein a clearance of said slit is in the range of 0.1 mm to 1/10 of an inner diameter of said pipe.
4 . A method as described in claim 1 , wherein a distance between said slit and said inline mixer is in the range of 1 mm to 250 mm.
5 . A method as described in claim 1 , wherein when a flow velocity of said additive is V 1 and a flow velocity of said polymer solution is V 2 , a following condition is satisfied:
1 ≦V 1/ V 2≦5
6 . A method as described in claim 1 ,
wherein said polymer solution has a viscosity in the range of 5000 cp to 500000 cp at 20° C., a shearing rate V 3 of said polymer solution satisfies a condition of 0.1 (1/s)≦V 3 ≦30(1/s), a Reynolds number of said polymer solution is at most 200; and wherein said additive has a viscosity in the range of 0.1 cp to 100 cp.
7 . A method as described in claim 1 , wherein an addition ratio of said additive is from 0.1% to 50% in flow volume.
8 . A solution casting method for producing a polymer film, comprising steps of:
dissolving a polymer to a solvent, so as to obtain a polymer solution;
passing said polymer solution through a pipe;
adding to said polymer solution an additive through a slit disposed in said pipe, said slit extending in a diameter direction of said pipe;
mixing and stirring a mixture of said polymer solution and said additive, such that a dope may be obtained; and
casting said dope on a support, so as to form said polymer film.
9 . An apparatus for producing a dope, comprising:
a pipe for passing a polymer solution through which a polymer is dissolved to a solvent;
an addition nozzle disposed in said pipe, for feeding an additive out to said polymer solution, a slit of said addition nozzle extending in a diameter direction of said pipe; and
an inline mixer for mixing said polymer solution and said additive such that said dope may be obtained.
10 . An apparatus as described in claim 9 , wherein said inline mixer is a static mixer which has an element formed by wrenching a rectangle plate, and a lengthwise direction of said slit is almost perpendicular to an upstream end of said element.