Pigmented polyimide films and methods relating thereto
View Patent ↗The present disclosure is directed to a base film having a thickness from 8 to 152 microns, a 60 degree gloss value from 2 to 35, an optical density greater than or equal to 2 and a dielectric strength greater than 1400 V/mil. The base film comprises a chemically converted (partially or wholly aromatic) polyimide in an amount from 63 to 96 weight percent of the base film. The base film further comprises a pigment and a matting agent. The matting agent is present in an amount from 1.6 to 10 weight percent of the base film, has a median particle size from 1.3 to 10 microns, and has a density from 2 to 4.5 g/cc. The pigment is present in an amount from 2 to 35 weight percent of the base film. The present disclosure is also directed to coverlay films comprising the base film in combination with an adhesive layer.
1. A base film comprising:
A. a chemically converted polyimide in an amount from 63 to 96 weight percent of the base film, the chemically converted polyimide being derived from:
a. at least 50 mole percent of an aromatic dianhydride, based upon a total dianhydride content of the polyimide, and
b. at least 50 mole percent of an aromatic diamine based upon a total diamine content of the polyimide;
B. a pigment, other than carbon black, present in an amount from 2 to 35 weight percent of the base film; and
C. a particulate matting agent that:
a. is silica and is present in an amount from 1.6 to 10 weight percent of the base film,
b. has a median particle size from 1.3 to 10 microns,
c. has a density from 2 to 4.5 g/cc,
and the base film has a 60 degree gloss from 2 to 35.
2. The base film in accordance with claim 1 wherein:
a. the aromatic dianhydride is selected from the group consisting of:
pyromellitic dianhydride,
3,3′,4,4′-biphenyl tetracarboxylic dianhydride,
3,3′,4,4′-benzophenone tetracarboxylic dianhydride,
4,4′-oxydiphthalic anhydride,
3,3′,4,4′-diphenyl sulfone tetracarboxylic dianhydride,
2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane,
bisphenol A dianhydride, and mixtures thereof; and
b. the aromatic diamine is selected from the group consisting of:
3,4′-oxydianiline,
1,3-bis-(4-aminophenoxy) benzene,
4,4′-oxydianiline,
1,4-diaminobenzene,
1,3-diaminobenzene,
2,2′-bis(trifluoromethyl) benzidene,
4,4′-diaminobiphenyl,
4,4′-diaminodiphenyl sulfide,
9,9′-bis(4-amino)fluorine and mixtures thereof.
3. The base film in accordance with claim 1 wherein the chemically converted polyimide is derived from pyromellitic dianhydride and 4,4′-oxydianiline.
4. A multilayer film comprising the base film of claim 1 and an adhesive layer.
5. The multilayer film in accordance with claim 4 , wherein the adhesive layer is an epoxy resin selected from the group consisting of:
bisphenol A epoxy resin, cresol novolac epoxy resin, phosphorus containing epoxy resin, and mixtures thereof.
6. The multilayer film in accordance with claim 4 , wherein the multilayer film is a coverlay film.
7. The base film in accordance with claim 1 , wherein the base film has a thickness from 8 to 152 microns.
8. The base film in accordance with claim 1 , wherein the chemically converted polyimide is created by a chemical conversion process that includes the use of a tertiary amine.
9. The base film in accordance with claim 8 , wherein the tertiary amine used in the chemical conversion process is pyridine.
10. The base film in accordance with claim 8 , wherein the tertiary amine used in the chemical conversion process is beta-picoline.
11. The base film in accordance with claim 1 , wherein the chemically converted polyimide is created by a chemical conversion process that includes the use of an anhydride dehydrating material.
12. The base film in accordance with claim 11 , wherein the anhydride dehydrating material used in the chemical conversion process is acetic anhydride.
13. The base film in accordance with claim 1 , wherein the base film has a 60 degree gloss from 10 to 35.
14. The base film in accordance with claim 1 , wherein the base film has an optical density greater than or equal to 2.
15. The base film in accordance with claim 1 , wherein the base film has a dielectric strength greater than 1400 V/mil.
16. The base film in accordance with claim 1 , wherein the pigment is present in an amount from 15 to 35 weight percent of the polyimide film.
17. A base film comprising:
A. a chemically converted polyimide in an amount from 63 to 96 weight percent of the base film, the chemically converted polyimide being derived from:
a. at least 50 mole percent of an aromatic dianhydride, based upon a total dianhydride content of the polyimide, and
b. at least 50 mole percent of an aromatic diamine based upon a total diamine content of the polyimide;
B. a dye present in an amount from 2 to 35 weight percent of the base film; and
C. a particulate matting agent, providing the base film with a 60 degree gloss from 2 to 35, that:
a. is silica and is present in an amount from 1.6 to 10 weight percent of the base film,
b. has a median particle size from 1.3 to 10 microns, and
c. has a density from 2 to 4.5 g/cc.
18. The base film in accordance with claim 17 , wherein the dye is present in an amount from 15 to 35 weight percent of the polyimide film.