Polyamide-imide film and method for producing same
An embodiment can provide a polyamide-imide film and a method for producing same, the film comprising a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound and a dicarbonyl compound, wherein, in an XRD graph with a section in which 2θ=8° to 32° as a baseline, the film shows a peak area of 50% or above around 2θ=23° with respect to a peak area seen around 2θ=15°.
1. A process for producing a polyamide-imide film, which comprises polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound to prepare a polyamide-imide polymer solution; charging the polymer solution into a tank; extruding and casting the polymer solution in the tank and then drying the cast polymer solution to prepare a gel sheet; thermally treating the gel sheet; lowering a temperature of the thermally treated gel sheet after the thermal treatment step, wherein the viscosity of the polymer solution is 100,000 to 300,000 cps, the thermal treatment is carried out in a temperature range of 80 to 500° ° C. at a temperature elevation rate of 2° C./min to 80° C./min for 5 to 40 minutes, the maximum temperature in the thermal treatment is 400 to 500° C., the temperature lowering step comprises a first temperature lowering step of reducing the temperature at a rate of 100° C./min to 1,000° C./min and a second temperature lowering step of reducing the temperature at a rate of 40° C./min to 400° C./min; the second temperature lowering step is performed after the first temperature lowering step; and the temperature lowering rate of the first temperature lowering step is faster than the temperature lowering rate of the second temperature lowering step.
2. The process for producing a polyamide-imide film of claim 1 , wherein the temperature inside the tank is −20 to 0° C.
3. The process for producing a polyamide-imide film of claim 1 , which further comprises vacuum degassing for 1 to 2 hours until the pressure in the tank is lowered to 0.2 to 0.4 bar after the step of charging the prepared polymer solution into the tank.
4. The process for producing a polyamide-imide film of claim 1 , which further comprises purging the tank with nitrogen gas at 1 to 2 atmospheres after the step of charging the prepared polymer solution into the tank.
5. The process for producing a polyamide-imide film of claim 1 , wherein the drying is carried out at a temperature of 60° ° C. to 150° C. for a period of time ranging from 5 minutes to 60 minutes.
6. The process for producing a polyamide-imide film of claim 1 , wherein the peak area in the vicinity of 2θ=23° is 50% or more based on the peak area in the vicinity of 2θ=15° when a base line is taken in the region between 2θ=8° and 32° in an XRD graph of the polyamide-imide film.