Polyimide films and electronic devices

Abstract

To provide polyimide films and electronic devices.SOLUTION: In a first aspect, a polyimide film includes a polyimide derived from a dianhydride and a diamine. The dianhydride includes pyromellitic dianhydride. The diamine includes a benzimidazole. The molar ratio between the dianhydride and the diamine that form the polyimide is in the range from 0.85:1 to 0.99:1. The polyimide film has Tg of 400°C or more, a tensile modulus of 6.0 GPa or more, and a coefficient of thermal expansion of 15 ppm / °C or less over the temperature range from 50 to 500°C. In a second aspect, an electronic device includes the polyimide film of the first aspect.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The field of this disclosure is polyimide films, electronic devices, and polyamic acid solutions. [Background technology]

[0002] Polyimide films with high-temperature stability, high tensile modulus, and low coefficient of thermal expansion (CTE) are required for flexible display applications, such as thin-film transistor (TFT) substrates in organic light-emitting diode (OLED) displays, electronic paper (E-paper), and touch sensor panels (TSP) for displays. For example, aromatic polyimides typically have a glass transition temperature (T) above 320°C. g They are extremely thermally stable and possess excellent foldability and windability, making them ideal candidates for use in various layers of flexible display devices such as touch sensor panels and cover windows. However, for flexible TFT substrates, in addition to good bending properties, the TFT manufacturing process requires a film that has a low CTE and is stable at temperatures above 400°C for extended periods while maintaining a high tensile modulus.

[0003] Polymer fibers containing benzimidazole form a highly oriented, ordered, densely packed molecular structure within the fiber. The introduction of intramolecular hydrogen bonds in the polymer backbone results in high strength and a high glass transition temperature (T). g ) and can exhibit a low CTE. Polybenzimidazole (PBI) is an extremely heat-resistant heterocyclic polymer. gAs a result, it exhibits excellent dimensional stability, rigidity, and toughness at temperatures exceeding 400°C, and is widely used in the aerospace / defense industry, in fire extinguishing equipment, and as a membrane in fuel cells in the form of fibers or resins. PBI also has a higher modulus of elasticity and strength than typical polyimides. Polyimide films containing benzimidazole-based diamines, such as 5-amino-2-(4-aminophenyl)benzimidazole (DAPBI), can have excellent thermal and oxidative stability under extreme conditions while maintaining good mechanical properties. However, the strong hydrogen bonding interactions introduced by benzimidazole can also present challenges in the processing of polyamic acid solutions used to manufacture polyimide films. For example, the robust roll-to-roll film manufacturing process for polyimide films requires good control of the viscosity and solids content of the liquid polyamic acid solution to enable a commercially sustainable process. (Patent Document 1) describes a film-forming polyimide copolymer having benzimidazole, in which the dianhydride used for the polyimide is a combination of pyromellitic dianhydride (PMDA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA). However, if one attempts to use PMDA as the sole dianhydride for the polymer without any BTDA, it is impossible to form a film. Similar efforts to produce robust polyimide films (Non-Patent Document 1) have shown that the use of PMDA and DAPBI alone as dianhydride and diamine monomers is problematic due to the rigidity of the polymer backbone. More recent efforts to produce PMDA / / DAPBI polyimide films ((Patent Documents 2) and (Patent Document 3)) have shown that high T g The present inventors describe a process for carefully handling low-solids, low-viscosity polyamic acid solutions to produce polyimide films having a temperature (over 400°C), however, these polyimide films are fragile and brittle, preventing the inventors from performing mechanical tests on these samples. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] US Patent No. 6,770,733 B2 [Patent Document 2] Chinese Patent Application Publication No. 106928481, Specification A [Patent Document 3] Japanese Patent Publication No. 2018-104525 [Patent Document 4] U.S. Patent No. 5,298,331 [Patent Document 5] U.S. Patent No. 2,801,185 [Patent Document 6] U.S. Patent No. 4,522,958 [Patent Document 7] U.S. Patent No. 5,648,407 [Patent Document 8] Japanese Patent No. 4406921B2 [Patent Document 9] Japanese Patent No. 4031624B2 [Patent Document 10] U.S. Patent No. 4,742,099 [Patent Document 11] U.S. Patent No. 5,227,244 [Patent Document 12] U.S. Patent No. 5,218,034 [Patent Document 13] U.S. Patent No. 5,543,222 [Non-patent literature]

[0005] [Non-Patent Document 1] S.Wang et al,J.Polym.Sci.Polym.Chem.(2009),47(8),2024-2031 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] A tough polyimide film with a high T, low CTE, and high tensile modulus that can be used for flexible device applications is still needed. g **Means for Solving the Problems**

[0007] In a first aspect, the polyimide film contains a polyimide derived from a dianhydride and a diamine. The dianhydride includes pyromellitic dianhydride, the diamine includes benzimidazole, the molar ratio of dianhydride to diamine forming the polyimide is in the range of 0.85:1 to 0.99:1, and the polyimide film has a T of 400 °C or higher, g a tensile modulus of 6.0 GPa or higher, and a coefficient of thermal expansion of 15 ppm / °C or less over a temperature range of 50 to 500 °C.

[0008] In a second aspect, the electronic device includes the polyimide film of the first aspect.

[0009] In a third aspect, the polyamic acid solution contains a dianhydride and a diamine. The dianhydride includes pyromellitic dianhydride, the diamine includes benzimidazole, the molar ratio of dianhydride monomer to diamine monomer is in the range of 0.85:1 to 0.99:1, and the polyamic acid solution has a solid content in the range of 10 to 25 weight percent and a viscosity in the range of 300 to 3000 poise.

[0010] The foregoing summary and the following detailed description are merely exemplary and explanatory and are not restrictive of the invention as defined in the appended claims. **Modes for Carrying Out the Invention**

[0011] In the first embodiment, the polyimide film comprises a polyimide derived from a dihydrohydride and a diamine. The dihydrohydride comprises pyromellitic dihydrohydride, and the diamine comprises benzimidazole, and the molar ratio of dihydrohydride to diamine forming the polyimide is in the range of 0.85:1 to 0.99:1, and the polyimide film is heated to temperatures of 400°C or higher. g It has a tensile modulus of 6.0 GPa or higher and a coefficient of thermal expansion of 15 ppm / °C or less over a temperature range of 50 to 500°C.

[0012] In one embodiment of the first aspect, the dianhydride further comprises up to 70 mole percent of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, or a mixture thereof, based on the total dianhydride content of the polyimide.

[0013] In another embodiment of the first aspect, benzimidazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzimidazole, 5-amino-2-(3-aminophenyl)benzimidazole, 6,6'-bis[2-(4-aminobenzene)benzimidazole], [2,2'-bi-1H-benzimidazole]-6,6'-diamine and mixtures thereof.

[0014] In yet another embodiment of the first aspect, the diamine further comprises a benzoxazole. In a specific embodiment, the benzoxazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzoxazole, 2,2'-p-phenylenebis[5-aminobenzoxazole], [2,2'-bibenzoxazole]-5,5'-diamine, 2,6-(4,4'-aminophenyl)benzobisxazole and mixtures thereof.

[0015] In yet another embodiment of the first aspect, the diamine further comprises up to 50 mole percent of p-phenylenediamine, m-phenylenediamine, m-tolidine, or a mixture thereof, based on the total diamine content of the polyimide.

[0016] In yet another embodiment of the first aspect, the polyimide film further comprises a crosslinking agent, a colorant, a matting agent, submicron particles, or a mixture thereof.

[0017] In a further embodiment of the first aspect, the polyimide film has a thickness in the range of 4 to 150 μm.

[0018] In a second embodiment, the electronic device includes the polyimide film of the first embodiment. In a specific embodiment, the polyimide film is used in a device component selected from the group consisting of thin-film transistor substrates, substrates for color filter sheets, cover films, and metal-clad laminates.

[0019] In a third embodiment, the polyamic acid solution comprises a dihydrogen anhydride and a diamine. The dihydrogen anhydride comprises pyromellitic dihydrogen anhydride, the diamine comprises benzimidazole, the molar ratio of dihydrogen anhydride monomer to diamine monomer is in the range of 0.85:1 to 0.99:1, and the polyamic acid solution has a solids content in the range of 10 to 25 weight percent and a viscosity in the range of 300 to 3000 poise.

[0020] In one embodiment of the third aspect, the dianhydride further comprises up to 70 mole percent of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, or a mixture thereof, based on the total dianhydride content of the polyimide.

[0021] In another embodiment of the third aspect, benzimidazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzimidazole, 5-amino-2-(3-aminophenyl)benzimidazole, 6,6'-bis[2-(4-aminobenzene)benzimidazole], [2,2'-bi-1H-benzimidazole]-6,6'-diamine and mixtures thereof.

[0022] In yet another embodiment of the third aspect, the diamine further comprises a benzoxazole. In a specific embodiment, the benzoxazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzoxazole, 2,2'-p-phenylenebis[5-aminobenzoxazole], [2,2'-bibenzoxazole]-5,5'-diamine, 2,6-(4,4'-aminophenyl)benzobisxazole and mixtures thereof.

[0023] In yet another embodiment of the third aspect, the diamine further comprises up to 50 mole percent of p-phenylenediamine, m-phenylenediamine, m-tolidine, or a mixture thereof, based on the total diamine content of the polyimide.

[0024] In yet another embodiment of the third aspect, the polyamic acid solution further comprises a crosslinking agent, a colorant, a matting agent, submicron particles, or a mixture thereof.

[0025] Many aspects and embodiments have been described above, but these are illustrative and not limiting. After reading this specification, those skilled in the art will understand that other aspects and embodiments are possible without departing from the scope of the invention. Other features and advantages of the invention will be apparent from the following detailed description and claims.

[0026] In one embodiment, a polyamic acid (PAA) solution having both pyromellitic dianhydride and a benzimidazole-based diamine is high T g, it can be used to form a polyimide film with a low CTE and a high tensile modulus. The PAA solution can have a high solids content and a high viscosity. By adjusting the molecular ratio of the dianhydride to the diamine monomer in the PAA, good control over the film-forming process enables the production of a robust polyimide film and the formation of a continuous self-supporting polyimide film using roll-to-roll processing. In one embodiment, the PAA solution can be cast on a copper foil to form a copper-clad laminate. In one embodiment, the polyimide film has a T g of 400 °C or higher, a tensile modulus of 6.0 GPa or higher, and a coefficient of thermal expansion of 15 ppm / °C or less over a temperature range of 50 to 500 °C. In one embodiment, the polyamic acid solution has a solids content of 10 to 25 wt% and a viscosity in the range of 300 to 3000 poise. In one embodiment, the molar ratio of the dianhydride monomer to the diamine monomer is in the range of 0.85:1 to 0.99:1. These flexible polyimide films are useful in a number of applications in the electronics industry where the benefits of their high T g (glass transition temperature), high tensile modulus, and low CTE (coefficient of thermal expansion) are desired, such as for TFT substrates and E-paper, and in the manufacture of flexible circuits and copper-clad laminates, and in display devices such as for cover windows, touch sensor panels, and other electronic device layers.

[0027] Depending on the context, "diamine" as used herein is intended to mean (i) in an unreacted form (i.e., a diamine monomer), (ii) in a partially reacted form (i.e., one or more portions of an oligomer or other polymer precursor derived from or otherwise resulting from the diamine monomer), or (iii) in a fully reacted form (one or more portions of a polymer derived from or otherwise resulting from the diamine monomer). The diamine can be functionalized in one or more portions depending on the particular embodiment selected for the implementation of the present invention.

[0028] In practice, the term “diamine” is not intended to be limited (or interpreted literally) in terms of the number of amine moieties in a diamine component. For example, (ii) and (iii) above include polymer materials that may have two, one, or zero amine moieties. Instead, diamines can be functionalized with additional amine moieties (in addition to the amine moieties at the ends of the monomers that react with the dihydrohydride to grow the polymer chain). Such additional amine moieties could be used to crosslink the polymer or to impart other functional groups to the polymer.

[0029] Similarly, the term “diacid anhydride,” as used herein, is intended to mean a component that reacts with (and is complementary to) a diamine and can react in combination to form an intermediate (which can then be cured into a polymer). Depending on the context, “acid anhydride,” as used herein, can mean not only the acid anhydride moiety itself, but also precursors of the anhydride moiety, such as (i) a pair of carboxylic acid groups (which can be converted to an acid anhydride by dehydration or a similar type of reaction); or (ii) an acid halide (e.g., acid chloride) ester functional group (or any other functional group currently known or to be developed in the future) that can be converted to an acid anhydride functional group.

[0030] Depending on the context, “diacid anhydride” can mean (i) an unreacted form (i.e., a diacid anhydride monomer, whether the acid anhydride functional group is in true acid anhydride form or in a precursor acid anhydride form as discussed in the preceding paragraph); (ii) a partially reacted form (i.e., one or more parts of an oligomer or other partially reacted precursor polymer composition that has reacted with or otherwise resulted from a diacid anhydride monomer); or (iii) a fully reacted form (one or more parts of a polymer that has come from or otherwise resulted from a diacid anhydride monomer).

[0031] Diacid anhydrides can be functionalized with one or more parts, depending on the specific embodiment selected in the implementation of the present invention. In fact, the term “diacid anhydride” is not intended to be limited (or to be interpreted literally) with respect to the number of acid anhydride parts in a diacid anhydride component. For example, (i), (ii) and (iii) (in the paragraph above) include organic substances that may have two, one, or zero acid anhydride parts, depending on whether the acid anhydride is in a precursor state or a reacted state. Alternatively, diacid anhydride components may be functionalized with additional acid anhydride-type parts (in addition to the acid anhydride part that reacts with the diamine to give a polymer). Such additional acid anhydride parts may be used to crosslink the polymer or to impart other functional groups to the polymer.

[0032] Methods and materials similar to or equivalent to those described herein may be used in carrying out or testing the present invention, but preferred methods and materials are described herein.

[0033] Where quantities, concentrations, or other values ​​or parameters are presented as a range, a preferred range, or a list of upper preferred values ​​and lower preferred values, this should be understood to specifically disclose all ranges formed by any pair of any upper limit or preferred value and any lower limit or preferred value, regardless of whether the ranges are disclosed individually. Where numerical values ​​of a range are enumerated herein, unless otherwise specified, that range is intended to include its endpoint and all integers and fractions within that range. The ranges of the present invention are not intended to be limited to the specific values ​​enumerated when defining a range.

[0034] When describing specific polymers, it should be understood that the applicant may refer to the polymers by the monomers used to manufacture them or the amounts of monomers used to manufacture them. Such descriptions do not have to include specific nomenclature used to describe the final polymer or product-by-process terminology, but any such reference to monomers and amounts should be interpreted as meaning that the polymers are manufactured from those monomers or those amounts of monomers, as well as the corresponding polymers and their compositions.

[0035] The materials, methods, and examples described herein are illustrative only and are not intended to be limiting unless specifically stated. As used herein, the terms “include,” “contain,” “incorporate,” “encompass,” “have,” “have,” or any other variation thereof are intended to have non-exclusive inclusion. For example, a method, process, article, or apparatus containing a list of elements is not necessarily limited to those elements alone, and may include other elements not explicitly listed or specific to such method, process, article, or apparatus. Furthermore, unless explicitly stated otherwise, “or” means comprehensive or not, not exclusive or. For example, condition A or B is satisfied by either one of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); and A and B are both true (or exist).

[0036] The use of “one (a)” or “one (an)” is also used to describe the elements and components of the present invention. This is done solely for convenience and to illustrate the general meaning of the present invention. This description should be read as including one or at least one, and the singular form also includes the plural form unless it is clearly intended otherwise.

[0037] Organic solvents A useful organic solvent for the synthesis of the polymer of the present invention is preferably capable of dissolving the polymer precursor material. Such a solvent should also have a relatively low boiling point, such as below 225°C, so that the polymer can be dried at a suitable (i.e., more convenient and less costly) temperature. Boiling points below 210, 205, 200, 195, 190, or 180°C are preferred.

[0038] Useful organic solvents include N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), methyl ethyl ketone (MEK), N,N'-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetramethylurea (TMU), glycol ethyl ether, diethylene glycol diethyl ether, 1,2-dimethoxyethane (monoglym), diethylene glycol dimethyl ether (diglym), 1,2-bis-(2-methoxyethoxy)ethane (triglycerim), gamma-butyrolactone and bis-(2-methoxyethyl) ether, tetrahydrofuran (THF), ethyl acetate, hydroxyethyl acetate glycol monoacetate, acetone, and mixtures thereof. In one embodiment, preferred solvents include N-methylpyrrolidone (NMP) and dimethylacetamide (DMAc).

[0039] Diamine In one embodiment, suitable diamines for forming a polyimide film include benzimidazole. Examples of suitable benzimidazoles include 5-amino-2-(4-aminophenyl)benzimidazole (DAPBI), 5-amino-2-(3-aminophenyl)benzimidazole (i-DAPBI), 6,6'-bis[2-(4-aminobenzene)benzimidazole], and [2,2'-bi-1H-benzimidazole]-6,6'-diamine. In one embodiment, suitable diamines further include benzoxazoles such as 5-amino-2-(4-aminophenyl)benzoxazole (DAPBO), 2,2'-p-phenylenebis[5-aminobenzoxazole], [2,2'-bibenzoxazole]-5,5'-diamine, and 2,6-(4,4'-aminophenyl)benzobisxazole.

[0040] In one embodiment, up to 50 mole percent of one or more additional diamines may be used (based on the total diamine content of the polyamic acid solution or polyimide).

[0041] In one embodiment, suitable additional diamines for forming a polyimide film include aliphatic diamines such as 1,2-diaminoethane, 1,6-diaminohexane, 1,4-diaminobutane, 1,5-diaminopentane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane (DMD), 1,11-diaminoundecane, 1,12-diaminododecane (DDD), 1,16-hexadecamethylenediamine, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and combinations thereof. Other suitable aliphatic diamines for carrying out the present invention include those having 6 to 12 carbon atoms or combinations of long-chain and short-chain diamines, as long as both expandability and flexibility are maintained. Long-chain aliphatic diamines can enhance flexibility.

[0042] In one embodiment, suitable additional diamines for forming a polyimide film include alicyclic diamines (which may be fully or partially saturated) such as cyclobutanediamines (e.g., cis- and trans-1,3-diaminocyclobutane, 6-amino-3-azaspiro[3.3]heptane and 3,6-diaminospiro[3.3]heptane), bicyclo[2.2.1]heptane-1,4-diamine, isophoronediamine, and bicyclo[2.2.2]octane-1,4-diamine. Other alicyclic diamines include cis-1,4-cyclohexanediamine, trans-1,4-cyclohexanediamine, 1,4-bis(aminomethyl)cyclohexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methyl-cyclohexylamine), and bis(aminomethyl)norbornane.

[0043] In one embodiment, preferred additional diamines for forming a polyimide film include 2,2'-bis(trifluoromethyl)benzidine (TFMB), trifluoromethyl-2,4-diaminobenzene, trifluoromethyl-3,5-diaminobenzene, 2,2'-bis-(4-aminophenyl)-hexafluoropropane, 4,4'-diamino-2,2'-trifluoromethyldiphenyl oxide, 3,3'-diamino-5,5'-trifluoromethyldiphenyl oxide, and 9.9'-Bis(4-aminophenyl)fluorene, 4,4'-trifluoromethyl-2,2'-diaminobiphenyl, 4,4'-oxy-bis-[2-trifluoromethyl)benzeneamine](1,2,4-OBABTF), 4,4'-oxy-bis-[3-trifluoromethyl)benzeneamine], 4,4'-thio-bis-[(2-trifluoromethyl)benzeneamine], 4,4'-thiobis[(3-trifluoromethyl)benzeneamine], 4 ,4'-sulfoxyl-bis-[(2-trifluoromethyl)benzeneamine, 4,4'-sulfoxyl-bis-[(3-trifluoromethyl)benzeneamine], 4,4'-keto-bis-[(2-trifluoromethyl)benzeneamine], 1,1-bis[4'-(4''-amino-2''-trifluoromethylphenoxy)phenyl]cyclopentane, 1,1-bis[4'-(4''-amino-2''-trifluoromethylphenoxy)phenyl] Crohexane, 2-trifluoromethyl-4,4'-diaminodiphenyl ether; 1,4-(2'-trifluoromethyl-4',4''-diaminodiphenoxy)benzene, 1,4-bis(4'-aminophenoxy)-2-[(3',5'-ditrifluoromethyl)phenyl]benzene, 1,4-bis[2'-cyano-3'(4''-aminophenoxy)phenoxy]-2-[(3',5'-ditrifluoromethyl)phenyl]benzene (6F Further examples of fluorinated aromatic diamines include C-diamine, 3,5-diamino-4-methyl-2',3',5',6'-tetrafluoro-4'-trifluoromethyldiphenyl oxide, 2,2-bis[4'(4''-aminophenoxy)phenyl]phthalein-3',5'-bis(trifluoromethyl)anilide (6FADAP), and 3,3',5,5'-tetrafluoro-4,4'-diamino-diphenylmethane (TFDAM). In certain embodiments, the fluorinated diamine is 2,2'-bis(trifluoromethyl)benzidine (TFMB).

[0044] In one embodiment, p-phenylenediamine (PPD), m-phenylenediamine (MPD), m-tolidine (m-TB), 2,5-dimethyl-1,4-diaminobenzene, 2,5-dimethyl-1,4-phenylenediamine (DPX), 2,2-bis-(4-aminophenyl)propane, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 4,4'-diaminobiphenyl, 4,4''-diaminoterphenyl, 4,4'-diaminobenzanilide, 4,4'-diaminophenyl Benzoate, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylmethane (MDA), 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, bis-(4-(4-aminophenoxy)phenyl sulfone (BAPS), 4,4'-bis-(aminophenoxy)biphenyl (BAPB), 4,4'-diaminodiphenyl ether (ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl Minobenzophenone, 4,4'-isopropylidenedianiline, 2,2'-bis-(3-aminophenyl)propane, N,N-bis-(4-aminophenyl)-n-butylamine, N,N-bis-(4-aminophenyl)methylamine, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, m-aminobenzoyl-p-aminoanilide, 4-aminophenyl-3-aminobenzoate, N,N-bis-(4-aminophenyl)aniline, 2,4-diamino Any number of additional diamines, such as nottoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,4-diamine-5-chlorotoluene, 2,4-diamine-6-chlorotoluene, 2,4-bis-(beta-amino-t-butyl)toluene, bis-(p-beta-amino-t-butylphenyl) ether, p-bis-2-(2-methyl-4-aminopentyl)benzene, m-xylylenediamine, and p-xylylenediamine, can be used to form polyimide films.

[0045] Other useful diamines include 1,2-bis-(4-aminophenoxy)benzene, 1,3-bis-(4-aminophenoxy)benzene, 1,2-bis-(3-aminophenoxy)benzene, 1,3-bis-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)-3-(3-aminophenoxy)benzene, 1,4-bis-(4-aminophenoxy)benzene, 1,4-bis-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)-4-(3-aminophenoxy)benzene, 2,2-bis-(4-[4-aminophenoxy]phenyl)propane (BAPP), 2,2'-bis-(4-phenoxyaniline)isopropylidene, 2,4,6-trimethyl-1,3-diaminobenzene, and 2,4,6-trimethyl-1,3-diaminobenzene.

[0046] diacid anhydride In one embodiment, pyromellitic dianhydride (PMDA) is a suitable dianhydride for forming a polyimide film. In one embodiment, up to 70 mole percent of one or more additional dianhydrides may be used (based on the total dianhydride content of the polyamic acid solution or polyimide). For example, any number of suitable additional dianhydrides can be used in the formation of a polyimide film. Dianhydrides can be used in their tetraacid form (or as mono, di, tri, or tetraesters of tetraacids) or as their diesteric acid halides (chlorides). However, in some embodiments, the dianhydride form may be preferred because it is generally more reactive than the acid or ester.

[0047] Suitable examples of additional dianhydrides include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA), 2,2',3,3'-biphenyltetracarboxylic acid dianhydride (i-BPDA), 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 2-(3',4'-dicarboxyphenyl)5,6-dicarboxybenzimidazole dianhydride, 2- (3',4'-Dicarboxyphenyl)5,6-Dicarboxybenzoxazole dianhydride, 2-(3',4'-Dicarboxyphenyl)5,6-Dicarboxybenzothiazole dianhydride, 3,3',4,4'-Benzophenonetetracarboxylic acid dianhydride (BTDA), 2,2',3,3'-Biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-Biphenyltetracarboxylic acid dianhydride, Bicyclo-[2,2,2]-Octene-(7)-2,3,5,6-Tetracarboxylic acid-2,3,5,6-Dianhydride, 4,4'-Thio-diphthalic acid anhydride, Bis(3 ,4-dicarboxyphenyl) sulfone dianhydride, bis(3,4-dicarboxyphenyl) sulfoxide dianhydride (DSDA), bis(3,4-dicarboxyphenyl oxadiazole-1,3,4) p-phenylene dianhydride, bis(3,4-dicarboxyphenyl) 2,5-oxadiazole 1,3,4-dianhydride, bis2,5-(3',4'-dicarboxydiphenyl ether) 1,3,4-oxadiazole dianhydride, 4,4'-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl) thioether dianhydride, bisphenol A dianhydride (BPADA), bisphenol S dianhydride, bis-1,3-isobenzofrandione, 1,4-bis(4,4'-oxyphthalic anhydride)benzene, bis(3,4-dicarboxyphenyl)methane dianhydride, cyclopentadienyltetracarboxylic acid dianhydride, ethylenetetracarboxylic acid dianhydride, perylene 3,4,9,10-tetracarboxylic acid dianhydride, tetrahydrofurantetracarboxylic acid dianhydride, 1,3-bis-(4,4'-oxydiphthalic anhydride)benzene, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,Examples include 6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, and thiophene-2,3,4,5-tetracarboxylic dianhydride.

[0048] In one embodiment, suitable additional dianhydrides include alicyclic dianhydrides such as cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride (CBDA), 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride (CPDA), hexahydro-4,8-ethano-1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetron (BODA), 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride (TCA), and meso-butane-1,2,3,4-tetracarboxylic acid dianhydride. In one embodiment, the alicyclic dihydrohydride can be present in an amount of about 70 mole percent or less based on the total dihydrohydride content of the polyimide.

[0049] In one embodiment, suitable additional dihydrohydrides for forming a polyimide film include fluorinated dihydrohydrides such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 9,9-bis(trifluoromethyl)-2,3,6,7-xanthenetetracarboxylic dihydrohydride. In a particular embodiment, the fluorinated dihydrohydride is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA).

[0050] Crosslinking agent In one embodiment, a crosslinking agent is used to manufacture a polymer film. By crosslinking polyimide, the polymer film may have improved mechanical properties and improved chemical resistance. Examples of crosslinking agents include Jeffamine® D-230, Jeffamine® D-400, Jeffamine® D-2000, Jeffamine® D-2010, Jeffamine® D-4000, Jeffamine® ED-600, Jeffamine® ED-900, Jeffamine® D-2003, Jeffamine® EDR-148, Jeffamine® THF-100, Jeffamine® THF-170, and Jeffamine® SD-2 Examples of crosslinking agents include polyetheramines such as 001, Jeffamine® D-205 and Jeffamine® RFD-270, piperazines, secondary amines such as N,N'-diisopropylethylenediamine, N,N'-diisopropyl-1,3-propanediamine and N,N'-dimethyl-1,3-propanediamine, and triamines such as 2,4,6-triaminopyrimidine (TAP), melamine, diethylenetriamine, Jeffamine® T-403, Jeffamine® T-3000, and Jeffamine® T-5000. In addition, many diamines that can be used as diamine monomers for polyimides, as described above, may also be useful as crosslinking agents. In one embodiment, the polyamic acid solution contains up to 10 mole percent of the crosslinking agent based on a composition of 100 mole percent of diamine and 85 to 99 mole percent of dihydrohydride. After imidization of the polyamic acid to form a polyimide film, some or all of the crosslinking agent may still remain in the polyimide film. In one embodiment, the polyimide film contains up to 10 mole percent of the crosslinking agent based on a composition of 100 mole percent of diamine and 85 to 99 mole percent of dihydrohydride.

[0051] Coloring agents In one embodiment, the polyimide film contains 1 to 40% by weight of a coloring agent such as a pigment or dye. In some embodiments, the polyimide film contains 1 to 40% by weight of a mixture of pigments and dyes. In some embodiments, the polyimide film contains any two between and any two of the following: 1, 5, 10, 15, 20, 25, 30, 35, and 40% by weight of a coloring agent.

[0052] Substantially, any pigment (or combination of pigments) can be used in carrying out the present invention. In some embodiments, useful pigments include, but are not limited to, barium lemon yellow, cadmium yellow lemon, cadmium yellow light, cadmium yellow middle, cadmium yellow orange, scarlet lake, cadmium red, cadmium vermilion, alizarin crimson, permanent magenta, van dyke brown, raw umber green, or burnt umber. In some embodiments, useful black pigments include cobalt oxide, Fe-Mn-Bi black, Fe-Mn oxide spinel black, (Fe,Mn)2O3 black, copper chromate black spinel, lamp black, bone black, bone ash, bone char, hematite, black iron oxide, mica iron oxide, black complex inorganic pigment (CICP), (Ni,Mn,Co)(Cr,Fe)2O4 black, aniline black, perylene black, anthraquinone black, chromium green black hematite, chromium iron oxide, pigment green 17, pigment black 26, pigment black 27, pigment black 28, pigment brown 29, pigment brown 35, pigment black 30, pigment black 32, pigment black 33, or mixtures thereof.

[0053] In some embodiments, the pigments are lithopone, zinc sulfide, barium sulfate, cobalt oxide, yellow iron oxide, orange iron oxide, red iron oxide, brown iron oxide, hematite, black iron oxide, mica iron oxide, chromium(III) green, ultramarine blue, ultramarine violet, ultramarine pink, iron cyanide blue, cadmium pigment, or lead chromate pigment.

[0054] In some embodiments, the pigment is a complex inorganic color pigment (CICP) such as spinel pigment, rutile pigment, zircon pigment, or bismuth vanadate yellow. In some embodiments, useful spinel pigments include, but are not limited to, Zn(Fe,Cr)2O4 brown, CoAl2O4 blue, Co(AlCr)2O4 blue-green, Co2TiO4 green, CuCr2O4 black, or (Ni,Mn,Co)(Cr,Fe)2O4 black. In some embodiments, useful rutile pigments include, but are not limited to, Ti-Ni-Sb yellow, Ti-Mn-Sb brown, Ti-Cr-Sb buff, zircon pigment, or bismuth vanadate yellow.

[0055] In another embodiment, the pigment is an organic pigment. In some embodiments, useful organic pigments include, but are not limited to, aniline black (pigment black 1), anthraquinone black, monoazo type, diazo type, benzimimidazolone, diaryllide yellow, monoazo yellow salt, dinitraniline orange, pyrazolone orange, azo red, naphthol red, azo condensation pigment, lake pigment, copper phthalocyanine blue, copper phthalocyanine green, quinacridone, diarylpyrrolopyrrole, aminoanthraquinone pigment, dioxazine, isoindolinone, isoindoline, quinophthalone, phthalocyanine pigment, idantrone pigment, pigment violet 1, pigment violet 3, pigment violet 19, or pigment violet 23. In yet another embodiment, the organic pigment is a vat dye pigment such as, but not limited to, perylene, perylene black, perinone, or thioindigo. A uniform dispersion system of isolated individual pigment particles (aggregates) tends to yield uniform color intensity. In some embodiments, the pigment is ground. In some embodiments, the average particle size of the pigment is between any two of the following sizes (and any two optionally included): 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 μm. In some embodiments, luminescent (fluorescent or phosphorescent) or pearlescent pigments can be used alone or in combination with other pigments or dyes.

[0056] In one embodiment, the colorant may be low conductivity carbon black. In some embodiments, the colorant contains any two between and any two of the following: 1, 5, 10, 15, and 20% by weight of low conductivity carbon black. In yet another embodiment, the colorant contains 2 to 9% by weight of low conductivity carbon black.

[0057] Low conductivity carbon black is intended to mean channel-type black, furnace black, or lamp black. In some embodiments, low conductivity carbon black is surface-oxidized carbon black. One method for evaluating the degree of surface oxidation (of carbon black) is to measure the volatile content of the carbon black. Volatile content can be measured by calculating the weight loss when calcined at 950°C for 7 minutes. Generally speaking, highly surface-oxidized carbon black (high volatile content) can be readily dispersed in a polymer precursor solution, which can then be imidized into the (well-dispersed) filler-containing polymer of the present disclosure. When carbon black particles (aggregates) do not come into contact with each other, electron tunneling, electron hopping, or other electron flow mechanisms are generally suppressed, resulting in lower conductivity. In some embodiments, low conductivity carbon black has a volatile content of 1% or more. In some embodiments, low conductivity carbon black has a volatile content of 5, 9, or 13% or more. In some embodiments, furnace black can be surface-treated to increase its volatile content. Typically, low-conductivity carbon black has a pH of less than 6.

[0058] A uniform dispersion system of isolated carbon black particles (aggregates) not only reduces conductivity but also tends to result in a uniform color intensity. In some embodiments, the low-conductivity carbon black is ground. In some embodiments, the average particle size of the low-conductivity carbon black is between any two of the following sizes (and any two of which are optionally included): 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 μm.

[0059] Matting agent In one embodiment, the polyimide film contains 0.5 to 20% by weight of a matting agent selected from the group consisting of silica, alumina, zirconia, boron nitride, barium sulfate, polyimide particles, calcium phosphate, talc, or mixtures thereof. In some embodiments, the polyimide film contains 0.5, 1, 5, 10, 15, and 20% by weight of the matting agent, including any two between and any two of the following. In one embodiment, the matting agent has a particle size in the range of 2 to 10 μm, or 3 to 9 μm, or 5 to 7 μm.

[0060] Submicron particles In one embodiment, the polyimide film contains at least one submicron particle in up to about 39 wt%, such as a submicron fumed metal oxide (also known as a heat-generating metal oxide) or a submicron colloidal metal oxide or a mixture thereof. In some embodiments, the submicron fumed metal oxide is fumed alumina, fumed silica, or a mixture thereof. In one embodiment, the polyimide film contains at least one submicron particle in up to 20 wt%, or up to 10 wt%, of a maximum. In one embodiment, the submicron particle has a particle size of less than about 1 μm. In one embodiment, the submicron particle has a particle size in the range of 0.01 to 1 μm or 0.05 to 0.5 μm.

[0061] The particle sizes of submicron particles, carbon black, and matting agents can be measured in the slurry by laser diffraction using particle size analyzers such as LA-930 (Horiba Instruments, Inc., Irvine CA), Mastersizer 3000 (Malvern Instruments, Inc., Westborough, MA), or LS-230 (Beckman Coulter, Inc., Indianapolis, IN). However, due to the tendency of submicron particles to aggregate, it may be more accurate to measure the particle size of these pulverized slurries by observation with an optical microscope.

[0062] Polyimide film In one embodiment, a polyimide film can be produced by combining a diamine and a dihydrohydride (monomer or other polyimide precursor form) with a solvent to form a polyamic acid solution. The dihydrohydride and diamine can be combined in molar ratios of 0.85:1 to 0.99:1, 0.90:1 to 0.99:1, 0.95:1 to 0.985:1, or 0.965:1 to 0.985:1. The molecular weight of the polyamic acid formed therefrom can be adjusted by adjusting the molar ratio of dihydrohydride to diamine, the solution viscosity, and the solids content. Instead of targeting a dihydrohydride-to-diamine ratio of 1:1 or greater than 1:1, having a small deficiency (less than 1:1 ratio) of dihydrohydride in the polyimide results in polyimide chains containing amine chain ends, which can increase film stability under higher humidity and higher acid environments. At these molar ratios, polyamic acid solutions with high viscosity and high solids content are easily processed and have high T g This allows for the formation of robust, flexible films with low CTE and high tensile modulus. In one embodiment, a polyamic acid solution containing PMDA and DAPBI monomers can be prepared with a viscosity in the range of 300 to 3000 poise, while having a solids content in the range of 10 to 25%, enabling large-scale roll-to-roll processing for forming polyimide films. In one embodiment, the polyamic acid solution can have a viscosity in the range of 500 to 2600, or 1000 to 2400, or 1300 to 2200 poise. In one embodiment, the polyamic acid solution can have a solids content in the range of 13 to 25% or 16 to 22%.

[0063] A useful method for producing a polyamic acid solution according to the present invention can be found in Patent Document 4, all of which are incorporated herein by reference. Numerous variations are also possible, as follows: (a) A method in which only the diamine is dissolved in a solvent, and then a dihydrohydride is added thereto in a ratio that allows control of the reaction rate. (b) A method in which only the diacid anhydride component is dissolved in the solvent, and then the amine component is added thereto in a ratio that allows control of the reaction rate. (c) A method in which a polyamic acid with an excess of diamine component and another polyamic acid with an excess of dihydrohydride component are formed in advance and then reacted with each other in a reactor in a manner that particularly yields a non-random or block copolymer. (d) A specific portion of the diamine component and the dihydrohydride component is reacted first, followed by the remaining diamine component, or vice versa. (e) A method in which components are added to any part or all of a solvent, either partially or as a whole, in any order, and any part or all of any component is added as a solution in any part or all of a solvent. (f) A method of first reacting one of the dihydroanhydride components with one of the diamine components to obtain a first polyamic acid. Then, a method of reacting another dihydroanhydride component with another diamine component to obtain a second polyamic acid. Then, a method of bonding the amide acid by one of several methods before imidation.

[0064] In one embodiment, the polyamic acid solution can be combined with (i) one or more dehydrating agents such as aliphatic acid anhydrides and / or aromatic acid anhydrides (acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, etc.) and (ii) one or more conversion chemicals such as catalysts such as aliphatic tertiary amines (triethylamine, etc.), aromatic tertiary amines (dimethylaniline, etc.) and heterocyclic tertiary amines (pyridine, alpha, beta, and gamma picolines (2-methylpyridine, 3-methylpyridine, 4-methylpyridine), isoquinoline, etc.).

[0065] In one embodiment, the conversion chemical may be an imidation catalyst (sometimes called an "imidation accelerator") that can help lower the imidation temperature and shorten the imidation time. Typical imidation catalysts can range from imidazoles, substituted pyridines such as 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, benzimidazole, isoquinoline, methylpyridine, and lutidine, and bases such as trialkylamines, as well as hydroxy acids such as isomers of hydroxybenzoic acid. The ratio of these catalysts in the polyamic acid layer and their concentrations will affect the imidation reaction rate and film properties.

[0066] In one embodiment, a polyamic acid solution can be optionally heated in the presence of an imidation catalyst to partially or completely imidize the polyamic acid and convert it to polyimide. The temperature, time, and concentration and selection of the imidation catalyst can affect the degree of imidization of the polyamic acid solution. Preferably, the solution should be substantially imidized. In one embodiment, more than 85%, more than 90%, or more than 95% of the amidic acid groups in a substantially polyimide solution are converted to polyimide, as measured by infrared spectroscopy.

[0067] In one embodiment, a solvation mixture (a substantially imidized solution) can be cast to form a polyimide film. In another embodiment, the solvation mixture (the first substantially imidized solution) can be precipitated in a poor solvent such as water or alcohol (e.g., methanol, ethanol, isopropyl alcohol) to isolate a solid polyimide resin. For example, isolation can be achieved by filtration, decantation, centrifugation and decantation of the supernatant, distillation or solvent removal in the gas phase, or other known methods for separating solid precipitates from a slurry. In one embodiment, the precipitate can be washed to remove the catalyst. After washing, the precipitate can be substantially dried, but does not need to be completely dried. The polyimide precipitate can be redissolved in a second solvent such as methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), ethyl acetate, methyl acetate, ethyl formate, methyl formate, tetrahydrofuran, acetone, DMAc, NMP, and mixtures thereof to form a second substantially imidized solution (casting solution), which can then be cast to form a polyimide film.

[0068] The casting solution may further contain one of a number of additives, such as processing aids (e.g., oligomers), antioxidants, light stabilizers, flame retardants, antistatic agents, heat stabilizers, UV absorbers, inorganic fillers, or various reinforcing agents. Examples of inorganic fillers include thermally conductive fillers, metal oxides, inorganic nitrides, and metal carbides. Common inorganic fillers include alumina, silica, diamond, clay, boron nitride, aluminum nitride, titanium dioxide, dicalcium phosphate, and fumed metal oxides. Low-coloring organic fillers such as polydialkylfluorene may also be used.

[0069] In one embodiment, the elastic modulus of the polyimide film can be increased by the presence of submicron fillers. The submicron fillers may be inorganic or organic and may be present in amounts between any two of the following percentages and any two of them selectively: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 weight percent of the polyimide film.

[0070] In one embodiment, the submicron filler may have a size of less than 550 nm in at least one dimension. In other embodiments, the filler may have a size of less than 500, less than 450, less than 400, less than 350, less than 300, less than 250, less than 200 nm, or less than 100 nm in at least one dimension (the filler may have various shapes in any dimension, and the filler shape may vary along any dimension, so "at least one dimension" is intended to be a numerical average along that dimension). The average aspect ratio of the filler may be 1 for spherical particles or greater than 1 for non-spherical particles. In some embodiments, the submicron filler is selected from the group consisting of needle-shaped fillers (aciculars), fibrous fillers, plate-shaped fillers, polymer fibers, and mixtures thereof. In one embodiment, the submicron filler is substantially non-aggregated. The submicron filler may be hollow, porous, or solid, or may have a core-shell structure in which one composition is in the core and the second composition is in the shell. In one embodiment, the submicron fillers of the present disclosure exhibit aspect ratios of at least 1:1, at least 2:1, at least 4:1, at least 6:1, at least 8:1, at least 10:1, at least 12:1, or at least 15:1.

[0071] In some embodiments, the submicron filler has a size of 100 nm or less in at least one dimension. In some embodiments, the filler is spherical, lenticular, or elliptical in shape and is a nanoparticle. In one embodiment, examples of submicron fillers include inorganic oxides such as silicon, aluminum, and titanium oxides, hollow (porous) silicon oxide, antimony oxide, zirconium oxide, indium tin oxide, antimony tin oxide, mixed titanium / tin / zirconium oxides, and binary, ternary, quaternary, and higher-order composite oxides of one or more cations selected from silicon, titanium, aluminum, antimony, zirconium, indium, tin, zinc, niobium, and tantalum. In one embodiment, nanoparticle composite materials (e.g., single or more core / shell structures) can be used in which one oxide encapsulates another oxide within a single particle.

[0072] In one embodiment, examples of submicron fillers include other ceramic compounds such as boron nitride, aluminum nitride, ternary or more compounds containing boron, aluminum and nitrogen, gallium nitride, silicon nitride, aluminum nitride, zinc selenide, zinc sulfide, zinc telluride, and combinations thereof, or higher-order compounds containing multiple cations and multiple anions.

[0073] In one embodiment, solid silicon dioxide nanoparticles can be prepared from a silicon dioxide sol (e.g., a colloidal dispersion of solid silicon dioxide nanoparticles in a liquid medium), particularly from amorphous, semicrystalline, and / or crystalline silica sols. Such sols can be prepared by various techniques and in various forms, including hydrosols (i.e., water acting as the liquid medium), organosols (i.e., an organic liquid acting as the liquid medium), and mixed sols (i.e., the liquid medium includes both water and an organic liquid). See, for example, the descriptions of techniques and forms disclosed in (Patent Document 5), (Patent Document 6), and (Patent Document 7). In one embodiment, the nanoparticles are suspended in a polar aprotic solvent, such as DMAc or other solvents compatible with polyamic acid or polyimide acid solutions. In another embodiment, solid silicon dioxide nanoparticles are prepared, for example, DMAC-ST (Nissan Chemical America Corporation, Houston TX), with a median nanosilica particle size of about 20 nm d 50 It can be commercially available as a colloidal dispersion or sol dispersed in a polar aprotic solvent, such as a solid silica colloid in dimethylacetamide containing 20-21% by weight of SiO2 and less than 1% by weight of water.

[0074] In one embodiment, submicron fillers can be porous and have pores of any shape. One example is when the pores contain voids with lower density and lower refractive index (e.g., air-containing voids) formed within an oxide shell such as silicon oxide, i.e., hollow silicon oxide nanoparticles. The thickness of the shell of the submicron filler affects the strength of the submicron filler. Since hollow silicon oxide particles are made to have a lower refractive index and increased porosity, the shell thickness is reduced, resulting in a decrease in the strength (i.e., fracture resistance) of the submicron filler. Methods for producing such hollow silicon oxide nanoparticles are known, as described, for example, in (Patent Document 8) and (Patent Document 9). Hollow silicon oxide nanoparticles can be obtained from JGC Catalysts & Chemicals Corporation, Japan.

[0075] In one embodiment, submicron fillers can be coated with a coupling agent. For example, nanoparticles can be coated with acrylic or methacrylic coupling agents derived from aminosilanes, phenylsilanes, or corresponding alkoxysilanes. Trimethylsilyl surface capping agents can be introduced to the surface of nanoparticles by reaction of the submicron filler with hexamethyldisilazane. In one embodiment, submicron fillers can be coated with a dispersant. In one embodiment, submicron fillers can be coated with a combination of a coupling agent and a dispersant. Alternatively, the coupling agent, dispersant, or a combination thereof can be directly incorporated into the polyimide film and do not necessarily need to be coated on top of the submicron filler.

[0076] In some embodiments, the submicron fillers are selected so as not to decompose on their own at the desired processing temperature or to generate off-gas. Similarly, in some embodiments, the submicron fillers are selected so as not to contribute to the degradation of the polymer.

[0077] In one embodiment, a polyamic acid solution can form a “green film” which is partly polyamic acid and partly polyimide and can be formed in a thermal conversion process. The green film generally contains about 50–75% by weight of polymer and 25–50% by weight of solvent. Generally, it should be strong enough to be substantially self-supporting. The green film can be prepared by casting the polyamic acid solution into a film form onto a suitable support such as a casting drum or belt, and removing the solvent by gently heating at a maximum of 150°C. A low percentage of amide acid units in the polymer, for example, up to 25%, can be converted into imide units. In one embodiment, the polyamic acid solution can be cast or coated onto a support such as an endless belt or rotating drum to form a green film. Alternatively, it can be cast onto a polymer support such as PET, other forms of Kapton® polyimide film (e.g., Kapton® HN or Kapton® OL film) or other polymer supports. The solvent-containing film can then be converted into a polyimide film by heating to partially or completely remove the solvent. In some embodiments of the present invention, the green film is separated from the carrier before it is completely dried. The final drying step can be carried out in conjunction with dimensional support or stabilization of the film. In other embodiments, the wet film is heated directly on the carrier.

[0078] In one embodiment, a substantially imidized polyimide solution can be cast or coated onto a support such as an endless belt or a rotating drum to form a film. Alternatively, it can be cast onto a polymer support such as PET, other forms of Kapton® polyimide film (e.g., Kapton® HN or Kapton® OL film) or other polymer carriers. The solvent-containing film can then be converted into a film by heating to partially or completely remove the solvent. In some embodiments of the present invention, the film is separated from the carrier before it is completely dried. The final drying step can be carried out along with dimensional support or stabilization of the film. In other embodiments, the film is heated directly on the carrier.

[0079] The thickness of the polyimide film can be adjusted depending on the intended purpose or end-use specifications of the film. In one embodiment, the polyimide film has a total thickness in the range of 4 to 150 μm, 5 to 100 μm, or 10 to 80 μm.

[0080] When polyimide film is used as a flexible TFT substrate for electronic devices such as flexible OLED displays, e-paper, or sensors, the tensile modulus of the substrate film must have a high modulus (above 6.0 GPa) because the polyimide film, supported by a glass substrate, will need to pass through the TFT formation process and then be smoothly debonded from the glass substrate without film deformation. Typically, the film-glass laminate undergoes high-temperature TFT (thin-film transistor) processing at 450°C for a long period of time, and therefore the T of the polyimide film is important. gThe temperature must be above 400°C to maintain good mechanical properties of the film at least throughout the TFT manufacturing process. The CTE match between the polyimide film and the glass substrate must be good to limit thermal stress at the polymer / glass junction and to avoid delamination, curling, and film cracking during TFT processing. In one embodiment, the polyimide film has a tensile modulus of 6.0 GPa or higher, or 7.0 GPa or higher, or 8.0 GPa or higher. In one embodiment, the polyimide film has a TTE of 400°C or higher, or 425°C or higher, or 450°C or higher. g In one embodiment, the polyimide film has a thermal expansion coefficient of 15 ppm / °C or less, or 10 ppm / °C or less, or 5 ppm / °C or less over a temperature range of 50 to 500°C.

[0081] metal clad laminate In one embodiment, the conductive layer of the present invention is i. Metal sputtering (optionally, followed by electroplating); ii. Foil lamination; and / or iii. Any conventional or unconventional method for applying a thin metal layer to a substrate It can be brought about by this.

[0082] Metal-clad laminates can be formed as single-area laminates or double-sided laminates by any number of known processes. In one embodiment, a lamination process can be used to form a metal-clad laminate having a polymer film or a multilayer polyimide film. In one embodiment, a first outer layer containing a first thermoplastic polyimide is placed between a first conductive layer and a core layer, and a second outer layer containing a second thermoplastic polyimide is placed on the opposite side of the core layer. In one embodiment, the second conductive layer is placed in contact with the second outer layer on the opposite side of the core layer. One advantage of this type of construction is that the lamination temperature of the multilayer film can be lowered to the lamination temperature required for the thermoplastic polyimide of the outer layer to bond to the conductive layer. In one embodiment, the conductive layer is a metal layer.

[0083] For example, the polymer film can be subjected to a pretreatment step before the step of applying the polymer film onto the metal foil. Examples of pretreatment steps include heat treatment, corona treatment, plasma treatment under atmospheric pressure, plasma treatment under reduced pressure, treatment with coupling agents such as silane and titanate, sandblasting, alkali treatment, acid treatment, and coating with polyamic acid. To improve adhesive strength, it is also generally possible to add various metal compounds, such as those disclosed in (Patent Document 10), (Patent Document 11), (Patent Document 12), and (Patent Document 13), which are incorporated herein by reference.

[0084] In addition, conductive metal surfaces can be treated with various organic and inorganic treatment agents (for the purpose of improving adhesion). These treatments include the use of silanes, imidazoles, and triazoles; oxide treatment and reduced oxide treatment; tin oxide treatment; and surface cleaning / roughening (known as micro-etching) with acid or alkaline reagents.

[0085] In further embodiments, the polyamic acid precursor (of the polyimide film of the present invention) may be coated onto a fully cured polyimide base film or directly onto a metal substrate and subsequently imidized by heat treatment. The polyimide base film may be prepared by either a chemical or thermal conversion process and may be surface-treated, for example, by chemical etching, corona treatment, or laser etching, to improve adhesion.

[0086] As used herein, the terms “conductive layer” and “conductive foil” mean a metal layer or metal foil (a thin composition having at least 50% of the conductivity of high-grade copper). Conductive foil is typically a metal foil. Metal foils do not need to be used as elements in their pure form; they can also be used as metal foil alloys, such as copper alloys containing nickel, chromium, iron, and other metals. Conductive layers can also be metal alloys, typically applied to the polyimide of the present invention by a sputtering process, followed by an electroplating process. In these types of processes, a metal seed coat layer is first sputtered onto the polyimide film. Finally, a thicker coating of metal is applied to the seed coat by electroplating or electrodeposition. Such sputtered metal layers may be hot-pressed even above the glass transition temperature of the polymer for enhanced peel strength.

[0087] Particularly preferred metal substrates are foils of rolled annealed copper or rolled annealed copper alloys. In many cases, it has been found advantageous to pre-treat the metal substrate before coating. This pre-treatment may include, but is not limited to, electrodeposition or immersion deposition of thin layers of copper, zinc, chromium, tin, nickel, cobalt, other metals, and alloys of these metals onto the metal. The pre-treatment may consist of chemical treatment or mechanical roughening. This pre-treatment has been found to allow for a further increase in the adhesion, and therefore the peel strength, of the polyimide layer. Apart from surface roughening, chemical pre-treatment also allows for the formation of metal oxide groups, further increasing the adhesion of the metal to the polyimide layer. This pre-treatment may be applied to both sides of the metal, enabling enhanced adhesion to the substrate on both sides.

[0088] In one embodiment, the metal-clad laminate may include a polymer film which is a single-layer or multilayer film, and a first metal layer bonded to the outer surface of a first outer layer of the multilayer film. In one embodiment, the metal-clad laminate may include a second metal layer bonded to the outer surface of a second outer layer of the multilayer film. In one embodiment, the first metal layer, the second metal layer, or both metal layers may be copper. In one embodiment, the metal-clad laminate of the present invention, which includes double-sided copper cladding, can be prepared by laminating copper foil on both sides of a single-layer or multilayer film.

[0089] Purpose In one embodiment, high T g High tensile strength and low CTE polyimide films can be used in electronic device applications such as flexible device layers for electronic devices, coverlays for printed circuit boards, or other electronic components in electronic devices, providing protection from physical damage, oxidation, and other contaminants that could adversely affect the function of electronic components.

[0090] In one embodiment, a polyimide film, which is a flexible device layer, can be used for any number of layers in electronic device applications such as organic electronic devices, where a combination of good high-temperature resistance stability and excellent mechanical properties is desired. Non-limiting examples of such layers include thin-film transistor (TFT) substrates for flexible displays such as organic light-emitting diode (OLED) displays, electronic paper (E-paper), and touch sensor panels (TSP), substrates for color filter sheets, cover films, and other device layers. The specific material property requirements for each application are unique and can be addressed by appropriate composition and processing conditions for the polyimide films disclosed herein. Organic electronic devices that may benefit from having a polyimide film include, but are not limited to, (1) devices that convert electrical energy into radiation (e.g., light-emitting diodes, light-emitting diode displays, lighting devices, lighting fixtures, or diode lasers), (2) devices that detect signals by electronic processes (e.g., photodetectors, photoconductive cells, photoresistors, photoswitches, phototransistors, photocells, infrared detectors, biosensors), (3) devices that convert radiation into electrical energy (e.g., photovoltaic devices or solar cells), (4) devices that convert light of one wavelength into light of a longer wavelength (e.g., down-converting phosphor devices), and (5) devices that include one or more electronic components including one or more organic semiconductor layers (e.g., transistors or diodes).

[0091] In one embodiment, a metal-clad laminate having a polyimide film is particularly useful as a packaging material for die-pad bonding of flexible printed circuit boards or semiconductor devices, or for CSP (chip-scale package), chip-on-film (COF), COL (chip-on-lead), LOC (lead-on-chip), multi-chip module ("MCM"), ball grid array ("BGA") or micro-ball grid array, and / or tape-automated bonding ("TAB").

[0092] In another embodiment, the polyimide film is useful for wafer-level integrated circuit packaging, where the composite material is manufactured using a polyimide film placed between a wafer containing multiple integrated circuit dies and a conductive layer (typically metal) having a thickness of less than 100 μm. In one embodiment (of wafer-level integrated circuit packaging), conductive passages are connected to the dies by conductive passages such as wire bonds, conductive metals, solder bumps, etc.

[0093] The advantageous characteristics of the present invention can be seen by referring to the following examples, which illustrate but do not limit the present invention. All parts and percentages are by weight unless otherwise specified. [Examples]

[0094] Test method Glass transition temperature and storage modulus Glass transition temperature (T g The storage modulus at 50°C and 400°C was measured using dynamic mechanical analysis (Q800 DMA, TA Instruments, New Castle, DE). These DMA profiles of the film were collected over a temperature range of 25°C to 520°C at a heating rate of 5°C / min.

[0095] coefficient of thermal expansion The coefficient of thermal expansion (CTE) of the film in both the longitudinal (MD) and transverse (TD) directions was measured by thermomechanical analysis (Q400 TMA, TA Instruments).

[0096] Tensile modulus, tensile strength, and elongation at break The tensile properties of the film (modulus of elasticity, strength, and elongation at break) were measured at room temperature according to the ASTM D882 test method using a 0.5 × 4 inch film sample and a crosshead speed of 2 inches / minute.

[0097] thickness The coating thickness was determined by measuring coated and uncoated samples at 10 positions intersecting the TD direction of the film using a contact-type FISCHERSCOPE MMS PC2 modular thickness gauge (Fisher Technology Inc., Windsor, CT).

[0098] Peel strength Peel strength was measured using a 0.5 × 3 inch film sample. The crosshead peeling rate was 2 inches / min using a 90° German wheel structure according to IPC test method 2.4.9D for die-cut specimens. CTE and dielectric constant (D) of polyimide film in copper cladding. k ) and dissipation rate (D f The values ​​are collected after etching off the entire Cu foil for each sample.

[0099] Comparative Example 1 For Comparative Example 1 (CE1), to prepare a polyamic acid (PAA) with a monomer composition of PMDA 1.0 / / PPD 0.7 / ODA 0.3, 6.497 g of p-phenylenediamine (PPD) and 5.156 g of 4,4'-diaminodiphenyl ether (ODA) were mixed with 120 g of dimethylacetamide (DMAc) at 25°C while stirring at 150 rpm. Then, 18.347 g of pyromellitic dianhydride (PMDA) was added, and the mixture was stirred for 3 hours. The prepolymer solution was adjusted (finished) to approximately 2000 poise by adding small amounts of 6 wt% PMDA solution in the DMAc while stirring at 50 rpm.

[0100] To prepare the film, the PAA solution was mixed for 2 minutes in a centrifugal planetary mixer (THINKY USA, Laguna Hills, CA) to obtain the solution. The solution was degassed using the centrifugal planetary mixer to remove gas from the polymer for 20 minutes at 2000 rpm, and then cast onto a glass plate at 25°C using a metal rod to produce a dry film of approximately 1.5 mil. The film on the glass substrate was heated on a hot plate at 120°C for 80 minutes to yield a green film with 65-70% solids content, which was then lifted from the glass surface and mounted on a 10 x 10 inch pin frame. The mounted film was placed in a furnace and heated from 120°C to 340°C (10°C / min), then transferred to a 400°C furnace and held for 8 minutes. The film was removed from the oven at "high" temperature and allowed to cool in the air.

[0101] Comparative Example 2 For Comparative Example 2 (CE2), to prepare PAA with a monomer composition of PMDA 1.0 / / MPD 0.35 / PPD 0.35 / ODA 0.3, 3.249 g of PPD, 3.249 g of m-phenylenediamine (MPD), and 5.156 g of ODA were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 18.347 g of PMDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0102] Comparative Example 3 For Comparative Example 3 (CE3), to prepare PAA with a monomer composition of PMDA 1.0 / / MPD 0.7 / ODA 0.3, 6.497 g of MPD and 5.156 g of ODA were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 18.347 g of PMDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0103] Comparative Example 4 For Comparative Example 4 (CE4), to prepare PAA with a monomer composition of PMDA 1.0 / / DAPBI 0.35 / PPD 0.35 / ODA 0.3, 6.035 g of 5-amino-2-(4-aminophenyl)benzimidazole (DAPBI), 2.910 g of PPD, and 4.619 g of ODA were mixed with 120 g of DMAc according to all the procedures of CE1, followed by the addition of 16.436 g of PMDA, and then finishing to approximately 2000 poise. The film was also prepared according to the procedure of CE1.

[0104] Comparative Example 5 For Comparative Example 5 (CE5), to prepare PAA with a monomer composition of PMDA 1.0 / / DAPBI 0.35 / MPD 0.35 / ODA 0.3, 6.035 g of DAPBI, 2.910 g of MPD, and 4.619 g of ODA were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 16.436 g of PMDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0105] Comparative Example 6 For Comparative Example 6 (CE6), to prepare PAA with a monomer composition of PMDA 0.7 / BPDA 0.3 / / PPD 0.7 / ODA 0.3, 6.099 g of PPD and 4.840 g of ODA were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 11.950 g of PMDA and 7.111 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0106] Comparative Example 7 For Comparative Example 7 (CE7), to prepare PAA with a monomer composition of PMDA 0.3 / BPDA 0.7 / PPD 0.7 / ODA 0.3, 5.638 g of PPD and 4.474 g of ODA were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 4.549 g of PMDA and 15.339 g of s-BPDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0107] Comparative Example 8 For Comparative Example 8 (CE8), to prepare PAA with a monomer composition of PMDA 0.7 / BPDA 0.3 / / PPD 0.7 / DAPBI 0.3, 5.983 g of PPD and 5.318 g of DAPBI were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 11.723 g of PMDA and 6.976 g of s-BPDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0108] Comparative Example 9 For Comparative Example 9 (CE9), to prepare PAA with a monomer composition of PMDA 0.3 / BPDA 0.7 / / PPD 0.7 / DAPBI 0.3, 5.539 g of PPD and 4.923 g of DAPBI were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 4.469 g of PMDA and 15.070 g of s-BPDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0109] Comparative Example 10 For Comparative Example 10 (CE10), to prepare PAA with a monomer composition of BPDA 1.0 / / DAPBI 1.0, 13.086 g of DAPBI was mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 17.168 g of s-BPDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0110] Comparative Example 11 For Comparative Example 11 (CE11), to prepare PAA with a monomer composition of PMDA 1.0 / / PPD 0.3 / ODA 0.7, 2.519 g of PPD and 10.884 g of ODA were mixed with 120 g of DMAc according to the CE1 procedure, followed by the addition of 16.597 g of PMDA, and then finishing to approximately 2000 poise. The film was also prepared according to the CE1 procedure.

[0111] Example 1 For Example 1(E1), to prepare a PAA with a monomer composition of PMDA 1.0 / / DAPBI 1.0, 12.411 g of DAPBI was mixed with 126 g of DMAc at 25°C while stirring at 150 rpm to form an opaque solution. Then, 11.589 g of PMDA was added, and the mixture became clear. The mixture was then stirred for 3 hours. While stirring at 50 rpm, the prepolymer solution was adjusted to 2048 poise (finishing) using small additions of 6 wt% PMDA solution in the DMAc, reaching the final stoichiometry of 0.97:1 dihydrohydride to diamine. The film was prepared according to the procedure of CE1.

[0112] Example 2 For Example 2 (E2), to prepare a PAA with a monomer composition of PMDA 0.9 / BPDA 0.1 / / DAPBI 1.0, 12.197 g of DAPBI was mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 10.202 g of PMDA and 1.600 g of s-BPDA, and then finishing to 2377 poise. The final stoichiometry was 0.981:1 dihydrohydride to diamine. The film was prepared according to the procedure in CE1.

[0113] Example 3 For Example 3(E), to prepare a PAA with a monomer composition of PMDA 0.85 / BPDA 0.15 / / DAPBI 1.0, 15.987 g of DAPBI was mixed with 168 g of DMAc according to all procedures in E1, followed by the addition of 11.818 g of PMDA and 4.195 g of s-BPDA, and then finishing to 2208 poise. The film was prepared according to the procedure in CE1.

[0114] Example 4 For Example 4 (E4), to prepare a PAA with a monomer composition of PMDA 0.8 / BPDA 0.2 / / DAPBI 1.0, 12.093 g of DAPBI was mixed with 126 g of DMAc according to all the procedures of E1, to which 9.527 g of PMDA and 2.380 g of s-BPDA were added, followed by finishing to 2250 poise. The films were prepared according to the procedure of CE1, except that they were held at 400°C for 7 minutes instead of 8 minutes.

[0115] Example 5 For Example 5 (E5), to prepare a PAA with a monomer composition of PMDA 0.7 / BPDA 0.3 / / DAPBI 1.0, 15.721 g of DAPBI was mixed with 168 g of DMAc according to all procedures in E1, followed by the addition of 10.092 g of PMDA and 6.188 g of s-BPDA, and then finishing to 2180 poise. The film was prepared according to the procedure in CE1.

[0116] Example 6 For Example 6 (E6), to prepare a PAA with a monomer composition of PMDA 1.0 / / DAPBI 0.9 / PPD 0.1, 11.478 g of DAPBI and 0.615 g of PPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 11.907 g of PMDA, and then finishing to 1934 poise. The film was prepared according to the procedure in CE1.

[0117] Example 7 For Example 7 (E7), to prepare a PAA with a monomer composition of PMDA 0.9 / BPDA 0.1 / / DAPBI 0.9 / PPD 0.1, 11.274 g of DAPBI and 0.604 g of PPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 10.478 g of PMDA and 1.643 g of s-BPDA, and then finishing to 1820 poise. The film was prepared according to the procedure in CE1.

[0118] Example 8 For Example 8 (E8), to prepare a PAA with a monomer composition of PMDA 1.0 / / DAPBI 0.8 / PPD 0.2, 10.491 g of DAPBI and 1.265 g of PPD were mixed with 126 g of DMAc according to the procedure of E1, followed by the addition of 12.244 g of PMDA, and then finishing to 2231 poise. The film was prepared according to the procedure of CE1.

[0119] Example 9 For Example 9 (E9), to prepare a PAA with a monomer composition of PMDA 0.9 / BPDA 0.1 / DAPBI 0.8 / PPD 0.2, 10.300 g of DAPBI and 1.242 g of PPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 10.769 g of PMDA and 1.689 g of s-BPDA, and then finishing to 2341 poise. The film was prepared according to the procedure in CE1.

[0120] Example 10 For Example 10 (E10), to prepare a PAA with a monomer composition of PMDA 1.0 / / DAPBI 0.9 / MPD 0.1, 11.478 g of DAPBI and 0.615 g of MPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 11.907 g of PMDA, and then finishing to 2011 poise. The film was prepared according to the procedure in CE1.

[0121] Example 11 For Example 11 (E11), to prepare a PAA with a monomer composition of PMDA 0.9 / BPDA 0.1 / / DAPBI 0.9 / MPD 0.1, 11.274 g of DAPBI and 0.604 g of MPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 10.478 g of PMDA and 1.643 g of s-BPDA, and then finishing to 2194 poise. The film was prepared according to the procedure in CE1.

[0122] Example 12 For Example 12 (E12), to prepare a PAA with a monomer composition of PMDA 1.0 / / DAPBI 0.8 / MPD 0.2, 10.491 g of DAPBI and 1.265 g of MPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 12.244 g of PMDA, and then finishing to 1280 poise. The film was prepared according to the procedure in CE1.

[0123] Example 13 For Example 13 (E13), to prepare a PAA with a monomer composition of PMDA 0.9 / BPDA 0.1 / DAPBI 0.8 / MPD 0.2, 10.300 g of DAPBI and 1.242 g of MPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 10.769 g of PMDA and 1.689 g of s-BPDA, and then finishing to 1331 poise. The film was prepared according to the procedure in CE1.

[0124] Example 14 For Example 14 (E14), to prepare a PAA with a monomer composition of PMDA 0.7 / BPDA 0.3 / / DAPBI 0.7 / PPD 0.3, 8.935 g of DAPBI and 1.847 g of PPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 8.194 g of PMDA and 5.024 g of s-BPDA, and then finishing to approximately 2000 poise. The film was prepared according to the procedure in CE1.

[0125] Example 15 For Example 15 (E15), to prepare a PAA with a monomer composition of PMDA 0.3 / BPDA 0.7 / DAPBI 0.7 / PPD 0.3, 8.334 g of DAPBI and 1.722 g of PPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 3.011 g of PMDA and 10.933 g of s-BPDA, and then finishing to approximately 2000 poise. The film was prepared according to the procedure in CE1.

[0126] Example 16 For Example 16 (E16), to prepare a PAA with a monomer composition of PMDA 0.3 / BPDA 0.7 / / DAPBI 0.5 / PPD 0.5, 6.275 g of DAPBI and 3.026 g of PPD were mixed with 126 g of DMAc according to all procedures in E1, followed by the addition of 3.174 g of PMDA and 11.526 g of s-BPDA, and then finishing to 1200 poise. The film was prepared according to the procedure in CE1.

[0127] Example 17 For Example 17 (E17), to prepare a PAA with a monomer composition of PMDA 1.0 / / DAPBI 1.0, 12.411 g of DAPBI was mixed with 126 g of DMAc while stirring at 150 rpm to form an opaque solution. Then, 11.589 g of PMDA was added, and the mixture became clear. The mixture was then stirred for 3 hours. The prepolymer solution was adjusted to 3000 poise (finishing) by adding small amounts of 6 wt% PMDA solution in the DMAc while stirring at 50 rpm, to reach the final stoichiometry of dihydrohydride to diamine at a ratio of 0.981:1.

[0128] To prepare a soluble polyimide solution, 103 g of DMAc was added to the PAA solution, and the solids content was reduced from 16% by weight to 9.5% by weight by stirring for 1 hour. While maintaining the solution at 40°C, 1.289 g of beta-picoline and 1.413 g of acetic anhydride were gradually added to the PAA solution to ensure that the viscosity of the solution was stable. The solution was stirred at 100 rpm and 80°C for 7 hours, and then cooled to room temperature.

[0129] To prepare the film, a polyimide solution was cast onto a glass plate at 25°C using a metal rod to produce a dry film of approximately 1.5 mils. The film on the glass substrate was heated on a hot plate at 80°C for 20 minutes, then lifted from the glass surface and mounted on a 10 x 10 inch pin frame. The mounted film was placed in a furnace and heated from 120°C to 250°C (10°C / min), and held at 250°C for 20 minutes. The film was removed from the oven at "high" temperature and allowed to cool in the air.

[0130] Example 18 For Example 18 (E18), to prepare a PAA with a monomer composition of PMDA 0.9 / BPDA 0.1 / / DAPBI 1.0, 12.197 g of DAPBI was mixed with 126 g of DMAc according to the procedure of E17, followed by the addition of 10.202 g of PMDA and 1.600 g of s-BPDA, and then finishing to 3000 poise. The final stoichiometry was 0.985:1 dihydrohydride to diamine.

[0131] To prepare a soluble polyimide solution, 103 g of DMAc was added, and the PAA solution was stirred for 1 hour to reduce the solid content from 16% by weight to 9.5% by weight. While maintaining the solution at 40°C, 1.266 g of beta-picoline and 1.388 g of acetic anhydride were gradually added to the PAA solution to ensure that the viscosity of the solution was stable. The solution was stirred at 100 rpm and 80°C for 7 hours, and then cooled to room temperature. The film was prepared according to the procedure in E17.

[0132] Table 1 summarizes the thermal and mechanical properties of CE1-CE11 and E1-E18. The CTE values ​​for CE7, E15, and E16 are their T g Since the temperature was below 450°C, measurements were taken over a range of 50-450°C. The CTE values ​​for E1-E14 are close to zero when measured over a range of 50-450°C.

[0133] [Table 1]

[0134] [Table 2]

[0135] Polyimide / copper-clad laminate Four polyimide / copper-clad laminates (CCLs) were prepared by casting different polyamic acid formulations (E1, E2, CE10, and E16) onto a 12 μm Cu foil (BHM-102F-HA-V2, JX Metals Corporation, Japan) using the following procedure, followed by thermal imidation to form the CCLs.

[0136] The PAA solution was degassed for 10 minutes and then cast onto the matte side (silane-treated side) of the Cu foil at 25°C using a metal rod to produce a dry film of approximately 1 mil (the copper foil was fixed to the glass plate before casting the solution). The wet PAA / Cu cladding on the glass substrate was heated on a hot plate at 120°C for 80 minutes, except for heating at 120°C for 30 minutes for E16, yielding a green film (65-70% solids) / Cu cladding multilayer. The multilayer on the glass was then placed in a nitrogen purging furnace and heated from room temperature to 50°C (1.25°C / min), then from 50°C to 400°C (10°C / min), and held at 400°C for 5 minutes. The film was cooled from 400°C to 50°C over 60 minutes in N2 protection and then allowed to cool to room temperature in air. The CCL was removed from the glass and tested for mechanical and electrical properties as shown in Table 2.

[0137] [Table 3]

[0138] Examples E19 and E20 For Examples 19 and 20 (E19 and E20), compositions PMDA 1.0 / / DAPBI 1.0 (E19) and PMDA 0.9 / BPDA 0.1 / / DAPBI 1.0 (E20) were prepared according to the procedure in E1, but by varying the ratio of dihydrohydride to diamine while maintaining a solid content of 16% by weight. Table 3 shows the change in viscosity of the PAA solution when the molar ratio of dihydrohydride to diamine changes from 0.80:1 to 0.985:1.

[0139] [Table 4]

[0140] By controlling the viscosity and solid content of the PAA solution and varnish used to form polyimide films, high T g Flexible films with low CTE and high tensile modulus could be easily manufactured when the molar ratio of dihydrohydride to diamine monomer was in the range of 0.85:1 to 0.99:1.

[0141] It should be noted that not all of the above activities are required in a general description, some of the activities may not be necessary, and additional activities may be performed in addition to those described. Furthermore, the order in which the activities are listed is not necessarily the order in which they are performed. After reading this specification, a person skilled in the art will be able to determine which activities can be used for their specific needs or requirements.

[0142] In the foregoing specification, the present invention has been described in relation to specific embodiments. However, those skilled in the art will understand that various modifications and variations can be made without departing from the scope of the invention, as described in the following claims. All features disclosed herein can be replaced by alternative features that serve the same, equivalent, or similar purposes. Accordingly, this specification and the drawings should be considered illustrative rather than restrictive, and all such modifications are intended to be encompassed within the scope of the invention.

[0143] Benefits, other advantages, and solutions to problems have been described above in relation to specific embodiments. However, none of these benefits, advantages, solutions to problems, or any elements that could produce or make more prominent any benefit, advantage, or solution should be construed as a critically important, required, or essential feature or element of any or all of the claims.

Claims

1. A polyimide film comprising a polyimide derived from dianhydride and a diamine, The aforementioned dianhydride includes pyromellitic dianhydride; The diamine comprises benzimidazole; The molar ratio of dianhydride to diamine forming the polyimide is in the range of 0.85:1 to 0.99:1, and the molar ratio refers to the ratio of monomers in the polyimide obtained after synthesis; and The polyimide film is subjected to a temperature of 400°C or higher. g A polyimide film having a tensile modulus of 6.0 GPa or higher and a coefficient of thermal expansion of 15 ppm / °C or lower over a temperature range of 50 to 500°C.

2. The polyimide film according to claim 1, wherein the dianhydride further comprises 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, or a mixture thereof in an amount of up to 70 mole percent based on the total dianhydride content of the polyimide.

3. The polyimide film according to claim 1, wherein the benzimidazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzimidazole, 5-amino-2-(3-aminophenyl)benzimidazole, 6,6'-bis[2-(4-aminobenzene)benzimidazole], [2,2'-bi-1H-benzimidazole]-6,6'-diamine and mixtures thereof.

4. The polyimide film according to claim 1, wherein the diamine further comprises benzoxazole.

5. The polyimide film according to claim 4, wherein the benzoxazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzoxazole, 2,2'-p-phenylenebis[5-aminobenzoxazole], [2,2'-bibenzoxazole]-5,5'-diamine, 2,6-(4,4'-aminophenyl)benzobisxazole, and mixtures thereof.

6. The polyimide film according to claim 1, wherein the diamine further comprises p-phenylenediamine, m-phenylenediamine, m-tolidine, or a mixture thereof, up to 50 mole percent based on the total diamine content of the polyimide.

7. The polyimide film according to claim 1, further comprising a crosslinking agent, a coloring agent, a matting agent, submicron particles, or a mixture thereof.

8. A polyimide film according to claim 1, having a thickness in the range of 4 to 150 μm.

9. An electronic device comprising the polyimide film described in claim 1.

10. The electronic device according to claim 9, wherein the polyimide film is used in a device component selected from the group consisting of thin-film transistor substrates, substrates for color filter sheets, cover films, and metal-clad laminates.

11. A polyamic acid solution containing a dianhydride and a diamine, The aforementioned dianhydride includes pyromellitic dianhydride; The diamine comprises benzimidazole; The molar ratio of dianhydride monomer to diamine monomer is in the range of 0.85:1 to 0.99:1, and the molar ratio refers to the ratio of monomers in the polyamic acid solution; and The polyamic acid solution is a polyamic acid solution having a solid content in the range of 10 to 25 weight percent and a viscosity in the range of 300 to 3000 poise.

12. The polyamic acid solution according to claim 11, further comprising up to 70 mole percent of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, or a mixture thereof, based on the total dianhydride content of the polyimide.

13. The polyamic acid solution according to claim 11, wherein the benzimidazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzimidazole, 5-amino-2-(3-aminophenyl)benzimidazole, 6,6'-bis[2-(4-aminobenzene)benzimidazole], [2,2'-bi-1H-benzimidazole]-6,6'-diamine and mixtures thereof.

14. The polyamic acid solution according to claim 11, wherein the diamine further comprises a benzoxazole.

15. The polyamic acid solution according to claim 14, wherein the benzoxazole is selected from the group consisting of 5-amino-2-(4-aminophenyl)benzoxazole, 2,2'-p-phenylenebis[5-aminobenzoxazole], [2,2'-bibenzoxazole]-5,5'-diamine, 2,6-(4,4'-aminophenyl)benzobisxazole, and mixtures thereof.

16. The polyamic acid solution according to claim 11, wherein the diamine further comprises up to 50 mole percent of p-phenylenediamine, m-phenylenediamine, m-tolidine, or a mixture thereof, based on the total diamine content of the polyimide.

17. The polyamic acid solution according to claim 11, further comprising a crosslinking agent, a coloring agent, a matting agent, submicron particles, or a mixture thereof.

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