Polyimide film and process for producing the same

Abstract

A process includes the steps of: casting or coating a polyamic acid organic solvent solution on a support and drying the polyamic acid organic solvent solution thereon, so as to form a partially cured and/or partially dried polyamic acid film; dipping the polyamic acid film in tertiary amine or a solution of tertiary amine, or coating tertiary amine or a solution of tertiary amine on the polyamic acid film; and drying the film while imidizing the polyamic acid. In another process, a chemical converting agent and a catalyst are mixed in an organic solvent solution of polyamic acid. After casting and heating the mixture on a support, a partially cured and/or partially dried polyamic acid film is detached from the support. The film contains, with respect to the remaining volatile component, not less than 50 parts of catalyst, not more than 30 parts of solvent, and not more than 20 parts of chemical converting agent and/or a chemical converting agent derived component. The remaining amic acid is imidized and the film is dried.

1 . A process for producing a polyimide film by deposition of a polyamic acid containing composition by casting and/or coating, 
 said process comprising the step of: 
 adding, to the polyamic acid containing composition, a curing agent that contains not less than 1 mole equivalent of a dehydrating agent with respect to the polyamic acid and not less than 0.2 mole equivalent of an imidizing catalyst with respect to the polyamic acid.  
   
     
     
         2 . The process as set forth in  claim 1 , wherein a mole ratio of the dehydrating agent and the imidizing catalyst is in a range of 1:0.15 to 1:0.75.  
     
     
         3 . The process as set forth in  claim 1  or  2 , wherein the dehydrating agent is contained in 1 to 5 mole equivalent with respect to the polyamic acid, and the imidizing catalyst is contained in 0.2 to 1.5 mole equivalent with respect to the polyamic acid.  
     
     
         4 . The process as set forth in any one of claims  1  through  3 , wherein the curing agent is added in 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the polyamic acid.  
     
     
         5 . The process as set forth in any one of claims  1  through  4 , wherein the curing agent is added to an organic solvent solution of the polyamic acid to obtain a resin solution composition whose viscosity at 0° C. is not more than 600 poise.  
     
     
         6 . The process as set forth in any one of claims  1  through  4 , wherein the curing agent is added to an organic solvent solution of the polyamic acid to obtain a resin solution composition whose viscosity at 0° C. is not more than 400 poise.  
     
     
         7 . The process as set forth in any one of claims  1  through  6 , wherein the imidizing catalyst is a tertiary amine.  
     
     
         8 . A polyimide film, which is produced by the process of any one of claims  1  through  7  with thickness unevenness of not more than 2.0 μm in a machine direction.  
     
     
         9 . The process as set forth in  claim 1 , wherein the dehydrating agent is contained in 1.0 to 3.0 mole equivalent with respect to the polyamic acid, and the imidizing catalyst is contained in not less than 0.3 mole equivalent with respect to the polyamic acid.  
     
     
         10 . The process as set forth in  claim 9 , wherein the imidizing catalyst is a tertiary amine.  
     
     
         11 . The process as set forth in  claim 9  or  10 , further comprising the step of: 
 continuously casting an organic solvent solution of the polyamic acid on a support to cover a width of not less than 1 m,  
 wherein the resulting polyimide film has 0.7 or greater ratio of maximum value to minimum value of tear propagation strength measured across an entire width, and 0.6 g or smaller R value of tear propagation strength measured at an outermost portion.  
 
     
     
         12 . A polyimide film, produced by continuously casting an organic solvent solution of the polyamic acid on a support to cover a width of not less than 1 m, having 0.7 or greater ratio of maximum value to minimum value of tear propagation strength measured across an entire width, and 0.6 g or smaller R value of tear propagation strength measured at an outermost portion.  
     
     
         13 . The process as set forth in  claim 1 , further comprising the steps of: 
 forming a gel film that has been partially cured and/or partially dried to be self-supporting in the casting and/or coating of the polyamic acid containing composition on the support; and    passing the gel film through a heating furnace with both ends of the gel film being fastened,    wherein: 
 (1) the dehydrating agent is contained in 1.0 to 5.0 mole equivalent with respect to an amic acid unit, and the imidizing catalyst is contained in 0.2 to 2.0 mole equivalent with respect to the amic acid unit, and  
 (2) an initial temperature of heating in the heating furnace is controlled to be no more than +100° C. of a temperature of the support and within a range of 150° C. to 250° C.  
   
     
     
         14 . The process as set forth in  claim 13 , wherein the gel film contains a remaining volatile component within 15% to 150%.  
     
     
         15 . The process as set forth in  claim 13  or  14 , wherein the polyamic acid is obtained by polycondensation of monomers which contain a diamine component and an acid dianhydride component as a raw material, and the diamine component contains not less than 20 mole % of paraphenylene diamine with respect to the entire diamine component.  
     
     
         16 . The process as set forth in any one of claims  13  through  15 , wherein the resulting polyimide film has a film width of 1250 mm or greater, a molecular orientation MOR-c of not more than 1.30 at any point of the film, and a tensile modulus of not less than 2.5 GPa and not more than 5.0 GPa.  
     
     
         17 . A polyimide film, having a film width of 1250 mm or greater, a molecular orientation MOR-c of not more than 1.30 at any point of the film, and a tensile modulus of not less than 2.5 GPa and not more than 5.0 GPa.  
     
     
         18 . A process for producing a polyimide film, comprising the steps of: 
 casting and/or coating and subsequently drying an organic solvent solution of polyamic acid on a support, so as to produce a gel film, which is a partially cured and/or partially dried polyamic acid film; and    imidizing the gel film to obtain the polyimide film,    said process producing the gel film by any one of processes (1) through (4): 
 (1) dipping the gel film in tertiary amine or in a solution of tertiary amine, or applying tertiary amine or a solution of tertiary amine onto the polyamic acid film; and  
 drying the gel film while imidizing the gel film to polyimide;  
 (2) continuously heating a polyamic acid composition on the support at temperatures of at least two levels;  
 detaching the gel film from the support; and  
 imidizing amic acid of the gel film and drying the gel film;  
 (3) detaching a polyamic acid composition on the support with a remaining volatile component, so that the gel film contains not less than 50 parts by weight of an imidizing catalyst and not more than 30 parts by weight of a solvent, and not more than 20 parts by weight of a dehydrating agent, with respect to 100 parts by weight of the remaining volatile component; and  
 imidizing remaining polyamic acid and drying the gel film;  
 (4) carrying out the step of imidizing the gel film to obtain the polyimide film by tenter heating in which a heat treatment is carried out on the gel film with fastened both ends, wherein a content of remaining volatile component of the gel film and an initial temperature of heating in the tenter heating are controlled to control modulus and coefficient of thermal expansion.  
   
     
     
         19 . The process as set forth in  claim 18 , further comprising in said process (1) of the gel film the step of: 
 removing waste droplets from a surface of the film after the gel film is dipped in or applied to the tertiary amine or the solution of tertiary amine.    
     
     
         20 . The process as set forth in  claim 18  or  19 , wherein the content of remaining volatile component of the gel film is not more than 5 wt % to 100 wt %.  
     
     
         21 . The process as set forth in any one of claims  18  through  20 , wherein percent imidization of the gel film is 50% or greater.  
     
     
         22 . The process as set forth in any one of claims  18  through  21 , wherein the tertiary amine is selected from the group consisting of quinoline, isoquinoline, β-picoline, and pyridine.  
     
     
         23 . A polyimide film, which is produced by the process of any one of claims  18  through  22 .  
     
     
         24 . The process as set forth in  claim 18 , wherein the imidizing catalyst in said process (2) of the gel film is a tertiary amine.  
     
     
         25 . The process as set forth in  claim 18  or  24 , wherein the step of continuously heating the polyamic acid composition on the support at temperatures of at least two levels in said process (2) of the gel film further comprises the steps of: 
 heating at a temperature T1 of 80° C. to 160° C.; and  
 heating at a temperature T2 of 120° C. to 200° C.  
 
     
     
         26 . A polyimide film, which is produced by the process of  claim 24  or  25 .  
     
     
         27 . A polyimide film with percent weight loss by heating of 0.2 wt % to 2.5 wt %, which is determined from  
       (percent weight loss by heating)=(X−Y)/Y,  where X is a film mass after 150° C. heating for 10 minutes and Y is a film mass after 450° C. heating for 20 minutes,    said percent weight loss by heating containing a 0.01 wt % or greater portion from a catalyst with respect to a total weight of the film.    
     
     
         28 . The process as set forth in  claim 18 , wherein the content of remaining volatile component of the gel film in said process (3) of the gel film is not more than 100 wt %, when a weight of the polyamic acid film after 450° C. heating for 20 minutes is used as a reference.  
     
     
         29 . The process as set forth in  claim 18  or  28 , wherein the imidizing catalyst is a tertiary amine.  
     
     
         30 . A polyimide film, which is produced by the process of  claim 28  or  29 .  
     
     
         31 . The process as set forth in  claim 18 , wherein, in said process (4) of the gel film, the content of remaining volatile component of the gel film is set within 50 wt % to 300 wt %, and an initial temperature in the tenter heating is set within 200° C. to 400° C.  
     
     
         32 . The process as set forth in  claim 31 , wherein the initial temperature of the tenter heating is set within 250° C. to 400° C. when the content of remaining volatile component of the gel film is 50 wt % to 150 wt %.  
     
     
         33 . The process as set forth in  claim 31 , wherein the initial temperature of the tenter heating is set within 200° C. to 350° C. when the content of remaining volatile component of the gel film is 150 wt % to 300 wt %.  
     
     
         34 . The process as set forth in any one of claims  18 ,  31 ,  32 , and  33 , wherein the polyamic acid is obtained from polycondensation of monomers which contain mainly aromatic tetracarboxylic dianhydride and aromatic diamine as a raw material, and wherein not less than 20 mole % to not less than 65 mole % of paraphenylenediamine with respect to a total aromatic diamine component is used.  
     
     
         35 . A polyimide film, produced by the process of any one of claims  31  through  34 , with a birefringence of 0.15 or greater.