Methods of reducing the amount of colorant in a multilayer film

Abstract

The present disclosure is directed to methods of reducing the amount of colorant in a multilayer film and achieving an L* color less than 30 and a 60 degree gloss value less than 10. The multilayer film has a first polyimide layer and a second polyimide layer containing a matting agent, submicron carbon black and submicron fumed metal oxide.

What is claimed is: 
     
         1 . A method of reducing the amount of colorant in a multilayer film and achieving an L* color less than 30 and a 60 degree gloss value less than 10, the method comprising:
 a) providing a first polyimide layer;   b) providing a polyamic acid solution containing polyamic acid, silica matting agent, and submicron carbon black for forming a second polyimide layer;   c) adding at least one submicron fumed metal oxide to the polyamic acid solution;   d) coating the polyamic acid solution on to the first polyimide layer; and   e) imidizing the coating to form the second polyimide layer on the first polyimide layer.   
     
     
         2 . The method of  claim 1 , wherein the first polyimide layer is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine. 
     
     
         3 . The method of  claim 1 , wherein the polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from i) blocks of pyromellitic dianhydride and 4,4′-oxydianiline and ii) blocks of pyromellitic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, oxydiphthalic dianhydride and 1,3-bis-(4-aminophenoxy) benzene, or a mixture thereof. 
     
     
         4 . The method of  claim 1 , wherein the submicron fumed metal oxide comprises fumed alumina, fumed silica or a mixture thereof. 
     
     
         5 . A method of reducing the amount of colorant in a multilayer film and achieving an L* color less than 30 and a 60 degree gloss value less than 10, the method comprising:
 a) providing a polyamic acid green film for forming a first polyimide layer;   b) providing a polyamic acid solution containing polyamic acid, silica matting agent, and submicron carbon black for forming a second polyimide layer;   c) adding at least one submicron fumed metal oxide to the polyamic acid solution;   d) coating the polyamic acid solution on to the polyamic acid green film; and   e) imidizing the coating and the polyamic acid green film to form the first and second polyimide layers.   
     
     
         6 . The method of  claim 5 , wherein the polyamic acid green film is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine. 
     
     
         7 . The method of  claim 5 , wherein the polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from i) blocks of pyromellitic dianhydride and 4,4′-oxydianiline and ii) blocks of pyromellitic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, oxydiphthalic dianhydride and 1,3-bis-(4-aminophenoxy) benzene, or a mixture thereof. 
     
     
         8 . The method of  claim 5 , wherein the submicron fumed metal oxide comprises fumed alumina, fumed silica or a mixture thereof. 
     
     
         9 . A method of reducing the amount of colorant in a multilayer film and achieving an L* color less than 30 and a 60 degree gloss value less than 10, the method comprising:
 a) providing a first polyamic acid solution containing a first polyamic acid for forming a first polyimide layer;   b) providing a second polyamic acid solution containing a second polyamic acid, silica matting agent, and submicron carbon black for forming a second polyimide layer;   c) adding at least one submicron fumed metal oxide to the second polyamic acid solution;   d) coextruding the second polyamic acid solution and the first polyamic acid solution; and   e) imidizing the coextruded layers to form the first and second polyimide layers.   
     
     
         10 . The method of  claim 9 , wherein the first polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine. 
     
     
         11 . The method of  claim 6 , wherein the second polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from i) blocks of pyromellitic dianhydride and 4,4′-oxydianiline and ii) blocks of pyromellitic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, oxydiphthalic dianhydride and 1,3-bis-(4-aminophenoxy) benzene, or a mixture thereof. 
     
     
         12 . The method of  claim 9 , wherein the submicron fumed metal oxide comprises fumed alumina, fumed silica or a mixture thereof. 
     
     
         13 . A method of reducing the amount of colorant in a multilayer film and achieving an L* color less than 30 and a 60 degree gloss value less than 10, the method comprising:
 a) providing a first polyamic acid solution containing a first polyamic acid for forming a first polyimide layer;   b) providing a second polyamic acid solution containing a second polyamic acid, a first silica matting agent, and a first submicron carbon black for forming a second polyimide layer;   c) providing a third polyamic acid solution containing a third polyamic acid, a second silica matting agent, and a second submicron carbon black for forming a third polyimide layer;   d) adding at least one first submicron fumed metal oxide to the second polyamic acid solution;   e) adding at least one second submicron fumed metal oxide to the third polyamic acid solution;   f) coextruding the first, second and third polyamic acid solutions, wherein the second and third polyamic acid solutions are in direct contact with opposite sides of the first polyamic acid solution; and   g) imidizing the coextruded layers to form the first, second and third polyimide layers.   
     
     
         14 . The method of  claim 13 , wherein the first polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine. 
     
     
         15 . The method of  claim 13 , wherein the second polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from i) blocks of pyromellitic dianhydride and 4,4′-oxydianiline and ii) blocks of pyromellitic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, oxydiphthalic dianhydride and 1,3-bis-(4-aminophenoxy) benzene, or a mixture thereof. 
     
     
         16 . The method of  claim 13 , wherein the third polyamic acid is derived from pyromellitic dianhydride and 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline, or derived from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 4,4′-oxydianiline and paraphenylenediamine, or derived from i) blocks of pyromellitic dianhydride and 4,4′-oxydianiline and ii) blocks of pyromellitic dianhydride and paraphenylenediamine, or derived from pyromellitic dianhydride, oxydiphthalic dianhydride and 1,3-bis-(4-aminophenoxy) benzene, or a mixture thereof. 
     
     
         17 . The method of  claim 13 , wherein the first submicron fumed metal oxide comprises fumed alumina, fumed silica or a mixture thereof. 
     
     
         18 . The method of  claim 13 , wherein the second submicron fumed metal oxide comprises fumed alumina, fumed silica or a mixture thereof. 
     
     
         19 . The method of  claim 13 , wherein the second and third polyimide layers are the same.