Coating solutions and crosslinked polymer films

Abstract

To provide coating solutions and crosslinked polymer films.SOLUTION: In a first aspect, a coating solution includes a soluble polymer and a crosslinking precursor. The soluble polymer includes an imide group. The crosslinking precursor includes a first amine group that is either reactive to or passivated toward crosslinking, and one or more additional amine groups, where the one or more additional amine groups have been passivated toward crosslinking such that the crosslinking precursor can be chemically converted, thermally converted, photo-converted or dissociated to form at least two reactive amines. In a second aspect, a process for forming a polymer film includes (a) casting a coating solution, (b) activating the crosslinking precursor using an external stimulus to form at least two reactive amines and crosslink the polymer, and (c) drying the polymer film. The coating solution includes a soluble polymer including an imide group, and a crosslinking precursor.SELECTED DRAWING: None

Description

Technical Field

[0001] The field of the present disclosure is coating solutions, crosslinked polymer films, electronic devices, and methods of forming the same.

Background Art

[0002] Polymer films such as polyimide films are used in a wide variety of applications in the electronics industry, taking advantage of the various mechanical, electrical, and optical properties they can provide, as well as the beneficial thermal and chemical durability required during the processing of various electronic components and during the use of electronic devices. Polymer films can be used not only in the manufacture of flexible circuits and copper-clad laminates, but also in display devices such as cover windows, touch sensor panels, and other device layers. However, it can be difficult to achieve the desired combination of these properties in a single film.

[0003] In some applications, soluble polymers having imide groups can be used to form polymer films at lower temperatures than films made using polymer precursors. Lowering the film-forming temperature can provide various advantages such as producing films with low color (such as low b*), producing thinner films using low-viscosity coating solutions, enabling very smooth polymer films at lower temperatures for use as carrier substrates, using more environmentally friendly solvent systems, and reducing the overall cost of film production.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] [Non-Patent Document 1] PGMWuts and TW Greene, Greene's Protective Groups in Organic Synthesis, 4th Ed., John Wiley&Sons, Inc. (2007) [Overview of the project] [Problems that the invention aims to solve]

[0006] However, soluble polymers containing imide groups do not possess the solvent resistance typically required in electronic component manufacturing to suppress the degradation of polymer films during production. Therefore, it is necessary to manufacture soluble polymer films that maintain good solvent resistance. [Means for solving the problem]

[0007] In a first embodiment, the coating solution comprises a soluble polymer and a crosslinking precursor. The soluble polymer comprises an imide group. The crosslinking precursor comprises a first amine group which is either reactive or inactivated for crosslinking, and one or more additional amine groups which are inactivated for crosslinking such that the crosslinking precursor can be chemically converted, thermally converted, photoconverted, or dissociated to form at least two reactive amines.

[0008] In a second embodiment, a method for forming a polymer film comprises (a) casting a coating solution, (b) activating a crosslinking precursor using an external stimulus to form at least two reactive amines and crosslink the polymer, and (c) drying the polymer film. The coating solution comprises a soluble polymer containing imide groups and a crosslinking precursor. The crosslinking precursor comprises a first amine group which is either reactive or inactivated for crosslinking, and one or more additional amine groups which are inactivated for crosslinking such that the crosslinking precursor can be chemically cleaved, thermally cleaved, photocleaved or dissociated to form at least two reactive amines.

[0009] The above summary and the following detailed description are illustrative and descriptive only and do not limit the invention as defined in the attached claims. [Modes for carrying out the invention]

[0010] In a first embodiment, the coating solution comprises a soluble polymer and a crosslinking precursor. The soluble polymer comprises an imide group. The crosslinking precursor comprises a first amine group which is either reactive or inactivated for crosslinking, and one or more additional amine groups which are inactivated for crosslinking such that the crosslinking precursor can be chemically converted, thermally converted, photoconverted, or dissociated to form at least two reactive amines.

[0011] In one embodiment of the first aspect, one or more additional amine groups are inactivated to form a site selected from the group consisting of carbamates, N-alkylamines, N,N-dialkylamines, N-arylamines, N,N-diarylamines, benzylamines, amides, sulfonamides, acids, and ammonium salts produced from silyl derivatives. In certain embodiments, the carbamate is thermally cleavable. In more specific embodiments, the thermally cleavable carbamate is selected from the group consisting of tert-butyloxycarbonyl, fluorenylmethoxycarbonyl, and benzylcarbamate. In another specific embodiment, the carbamate is photocleavable, and the photocleavable carbamate is selected from the group consisting of 3,5-dimethoxybenzylcarbamate, m-nitrophenylcarbamate, and o-nitrobenzylcarbamate. In yet another specific embodiment, the amide is selected from the group consisting of formamide, trifluoroacetamide, trichloroacetamide, chloroacetamide, phenylacetamide, 3-phenylpropanamide, 3-pyridylcarboxamide, N-benzoylphenylalanyl, and benzamide. In yet another specific embodiment, the amide may be thermally cleaved, chemically cleaved, photocleaved, dissociated, or a mixture thereof. In yet another specific embodiment, the ammonium salt is produced from an acid selected from the group consisting of acetic acid, butyric acid, pivalic acid, hydrochloric acid, and sulfuric acid, and the ammonium salt may be thermally dissociated to form a reactive amine.

[0012] In another embodiment of the first aspect, the crosslinking precursor is selected from a single polyfunctional precursor, a combination of multiple monofunctional precursors, or a mixture thereof.

[0013] In yet another embodiment of the first aspect, the soluble polymer is selected from the group consisting of polyamides, poly(amide-imide), poly(ether-imide), poly(ester-imide), copolymers containing amide, ester or ether groups, and mixtures thereof.

[0014] In yet another embodiment of the first aspect, the coating solution further comprises a filler selected from the group consisting of nanoparticles, colorants, matting agents, submicron particles, thermally conductive fillers, electrically conductive fillers, and mixtures thereof. In certain embodiments, the colorant comprises low conductivity carbon black.

[0015] In a second aspect, a method of forming a polymer film comprises (a) casting a coating solution, (b) using an external stimulus to activate a crosslinking precursor to form at least two reactive amines and crosslink the polymer, and (c) drying the polymer film. The coating solution comprises a soluble polymer containing imide groups and a crosslinking precursor. The crosslinking precursor comprises a first amine group that is either reactive or inactivated with respect to crosslinking, and one or more additional amine groups that are inactivated with respect to crosslinking such that the crosslinking precursor can be chemically cleaved, thermally cleaved, photocleaved, or dissociated to form at least two reactive amines.

[0016] In one embodiment of the second aspect, the external stimulus is heat, light, or a different chemical species.

[0017] Although many aspects and embodiments have been described above, these are merely illustrative and not limiting. After reading this specification, those skilled in the art will recognize 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 the claims.

[0018] In one embodiment, a crosslinked polymer film can be produced by an inactivation crosslinking process using a coating solution having a soluble polymer and a crosslinking precursor, the soluble polymer containing imide groups. The crosslinking precursor includes a first amine group that is either reactive or inactivate for crosslinking, and one or more additional amine groups that are inactivated for crosslinking, so that the crosslinking precursor can be activated by an external stimulus to form at least two reactive amines. After activation, the polymer can be crosslinked. Examples of soluble polymers having imide groups include polyimides, poly(amide-imides), poly(ester-imides), poly(ether-imides), copolymers containing imides, amides, esters, and ether groups, and mixtures thereof. As used herein, the term “inactivate for crosslinking” is used to describe amine groups that inhibit reactivity and / or are inactive to the soluble polymer having imide groups upon initial introduction, but are later activated to react and crosslink the soluble polymer. In this form, the functionalized amine groups significantly delay or inhibit the crosslinking of the polymer, which would render the polymer insoluble before film formation. The crosslinking precursor can then be activated to form at least two reactive amines, thereby causing crosslinking of the polymer. By inactivating the crosslinking reaction until after film formation, a polymer film with excellent solvent resistance can be formed.

[0019] In one embodiment, the deactivated crosslinking reaction is due to the presence of a deactivating group that is converted (e.g., cleaved or dissociated) upon exposure to an external stimulus to form a reactive amine, and remains inert or is kinetically inhibited (i.e., deactivated) under the initial film fabrication and processing conditions. When the deactivating group is converted to form a reactive amine, these compounds are activated and participate in a chemical reaction that crosslinks the polymer chains within the film. In one embodiment, the external stimulus is heat. In this case, one or more of the initially deactivated amine groups are cleaved or dissociated by a thermally initiated process to become reactive, enabling the crosslinker to crosslink the film. In one embodiment, the external stimulus is irradiation by a light source. In this case, one or more of the initially deactivated amine groups are converted by a photoinitiated process to form a reactive amine. In one embodiment, the external stimulus is a different chemical species. In this case, one or more of the initially deactivated amine groups are converted by a chemically initiated process to form a reactive amine. In one embodiment, the external stimulus is any combination of the above stimuli.

[0020] Depending on the context, as used herein, "diamine" is intended to mean (i) an unreacted form (i.e., a diamine monomer), (ii) a partially reacted form (i.e., one or more portions of an oligomer or other polymer precursor derived from or resulting from a diamine monomer), or (iii) a fully reacted form (one or more portions of a polymer derived from or resulting from a diamine monomer). The diamine can be functionalized at one or more sites depending on the specific embodiment selected for the implementation of the present invention.

[0021] 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 polymeric materials that may have two, one, or zero amine moieties. Alternatively, diamines can be functionalized with additional amine moieties (in addition to the monomer-terminal amine moieties that react with the dianhydride to grow the polymer chain). Such additional amine moieties may be used to crosslink the polymer or to impart other functional groups to the polymer.

[0022] Similarly, as used herein, the term “dianhydride” is intended to mean a (complementary) component that reacts with a diamine, which can react in combination to form an intermediate (which can then be cured into a polymer). Depending on the context, as used herein, “anhydride” may mean not only the anhydride moiety itself, but also precursors of anhydride moieties, such as: (i) a pair of carboxylic acid groups (which can be converted to an anhydride by dehydration or a similar type of reaction), or (ii) an acid halide (e.g., chloride) ester functional group (or any other functional group currently known or to be developed in the future) that can be converted to an anhydride functional group. Acyl chloride monomers can also be used as reagents for forming amide groups in poly(amide-imide) or other amide-containing copolymers by reaction of acid chloride-containing monomers with amine-containing monomers.

[0023] Depending on the context, “dihydrohydride” can mean (i) an unreacted form (i.e., the dihydrohydride monomer as described in the paragraph above, regardless of whether the anhydride functional group is in true anhydride form or precursor anhydride form), (ii) a partially reacted form (i.e., one or more parts of an oligomer or other partially reacted or precursor polymer composition that has reacted with or resulted from a dihydrohydride monomer), or (iii) a fully reacted form (one or more parts of a polymer that is derived from or results from a dihydrohydride monomer).

[0024] Dianhydrides can be functionalized with one or more sites depending on the specific embodiment selected in the implementation of the present invention. In practice, the term “dianhydride” is not intended to be limited (or to be interpreted literally) with respect to the number of anhydride sites in a dianhydride component. For example, (i), (ii) and (iii) (in the paragraph above) include organic substances that may have two, one, or zero anhydride sites, depending on whether the anhydride is in a precursor state or a reacted state. Alternatively, dianhydride components can be functionalized with further anhydride-type sites (in addition to the anhydride sites that react with diamines to give polymers). Such further anhydride sites may be used to crosslink polymers or to impart other functional groups to polymers.

[0025] 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.

[0026] Where quantities, concentrations, or other values ​​or parameters are presented as a range, a preferred range, or an enumeration 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 separately. Where numerical values ​​of a range are enumerated herein, unless otherwise specified, the 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.

[0027] It should be understood that in descriptions of specific polymers, the applicant may refer to polymers by the monomers used to produce them or the amounts of monomers used to produce them. Such descriptions do not necessarily have to include a 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 polymer is made from those monomers or those amounts of monomers, and the corresponding polymer and their composition.

[0028] The materials, methods, and examples described herein are illustrative only and are not intended to be limiting unless specifically stated.

[0029] As used herein, the terms “include,” “contain,” “incorporate,” “contain,” “have,” “possess,” or any other variation thereof are intended to encompass non-exclusive inclusion. For example, a method, process, article or apparatus that includes a list of elements may not necessarily be limited to those elements alone, and may include other elements that are not explicitly listed or that are inherent to such method, process, article or apparatus. Furthermore, unless explicitly stated otherwise, “or” means comprehensive or not exclusive or. For example, condition A or B is satisfied by any 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 both A and B are true (or exist).

[0030] Furthermore, the use of “one (a)” or “one (an)” is used to represent 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 interpreted as including one or at least one, and the singular form also includes the plural form unless it is clear that this is not the case.

[0031] Organic solvents The organic solvent useful for the synthesis of the soluble 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 moderate (i.e., more convenient and less costly) temperature. Boiling points below 210, 205, 200, 195, 190, or 180°C are preferred.

[0032] 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).

[0033] Diamine In one embodiment, suitable diamines for forming soluble polymers include aliphatic diamines such as 1,2-diaminoethane, 1,6-diaminohexane (HMD), 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, trans-1,4-diaminocyclohexane (CHDA), isophoronediamine (IPDA), bicyclo[2.2.2]octane-1,4-diamine, and combinations thereof. Other aliphatic diamines suitable 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 developability and flexibility are maintained. Long-chain aliphatic diamines can enhance flexibility.

[0034] In one embodiment, diamines suitable for forming soluble polymers 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.

[0035] In one embodiment, suitable diamines for forming soluble polymers 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] Cyclohexane, 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 Examples of fluorinated aromatic diamines include C-diamine, 3,5-diamino-4-methyl-2',3',5',6'-tetrafluoro-4'-tri-fluoromethyldiphenyl 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).

[0036] Other diamines useful for forming soluble polymers include p-phenylenediamine (PPD), m-phenylenediamine (MPD), 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'-diaminophenylbenzoate, 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'-diamino Nodiphenyl ether, 4,4'-diaminobenzophenone, 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- Examples include (4-aminophenyl)aniline, 2,4-diaminotoluene, 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.

[0037] Other useful diamines for forming soluble polymers include 1,2-bis-(4-aminophenoxy)benzene, 1,3-bis-(4-aminophenoxy)benzene (RODA), 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.

[0038] dianhydride In one embodiment, any number of suitable dianhydrides can be used in the formation of a soluble polymer. The 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.

[0039] Suitable examples of dianhydrides include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (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, and 2-(3',4'-dicarboxyphenyl)5,6-dicarboxybenzothiazo Dianhydride, 2,2',3,3'-benzophenonetetracarboxylic acid dianhydride, 2,3,3',4'-benzophenonetetracarboxylic acid 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]-octen-(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-dicarboxyphenyloxadiazole-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), bispheno 1,3-bis-(4,4'-oxydiphthalic anhydride), 2,2-bis(3,4-dicarboxyphenyl)methane dianhydride, cyclopentadienyltetracarboxylic acid dianhydride, ethylenetetracarboxylic acid dianhydride, perylene 3,4,9,10-tetracarboxylic acid dianhydride, pyromellitic acid dianhydride (PMDA), tetrahydrofurantetracarboxylic acid dianhydride, 1,3-bis-(4,4'-oxydiphthalic anhydride), 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.

[0040] In one embodiment, suitable 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 dianhydride may be present in an amount of about 70 mole percent or less based on the total content of dianhydrides in the polymer.

[0041] In one embodiment, suitable dianhydrides for forming a soluble polymer include fluorinated dianhydrides such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 9,9-bis(trifluoromethyl)-2,3,6,7-xanthenetetracarboxylic acid dianhydride.

[0042] In one embodiment, useful acyl chloride-containing monomers for forming poly(amide-imide) include terephthaloyl chloride (TPCI), isophthaloyl chloride (IPCI), biphenyl dicarbonyl chloride (BPCI), naphthalenedicarbonyl chloride, terphenyl dicarbonyl chloride, 2-fluoro-terephthaloyl chloride, and trimellitic anhydride.

[0043] In one embodiment, the poly(ester-imide) may further include a polyol that can react with a carboxylic acid or ester acid halide to form an ester bond.

[0044] The dihydric alcohol component can be almost any alcoholic diol containing two esterifiable hydroxyl groups. Suitable mixtures of diols may also be included. Suitable diols for use herein include, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentiglycol, and the like.

[0045] The polyhydric alcohol component can be almost any polyhydric alcohol containing at least three esterifiable hydroxyl groups, in order to provide the advantages of the synthetic process described above in the present invention. Mixtures of such polyhydric alcohols can be appropriately used. Suitable polyhydric alcohols include, for example, tris(2-hydroxyethyl) isocyanurate, glycerin, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, and mixtures thereof.

[0046] In some cases, useful diamine and dianhydride monomers contain ester groups. Examples of these monomers are diamines such as 4-aminophenyl-4-aminobenzoate and 4-amino-3-methylphenyl-4-aminobenzoate, and dianhydrides such as p-phenylenebis(trimellitate) dianhydride.

[0047] In some cases, useful diamine and dianhydride monomers contain an amide group. Examples of these monomers include diamines such as 4,4'-diaminobenzamide (DABAN) and dianhydrides such as N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide) and N,N'-(9H-fluorene-9-ylidenedi-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide].

[0048] A higher-order copolymer having an imide group may contain any of the above monomers.

[0049] Crosslinking precursor In one embodiment, the crosslinking precursor is used in a coating solution that forms a polymer film. By crosslinking the polymer, the polymer film can have not only improved mechanical properties but also improved chemical resistance. Examples of crosslinking precursors include polyetheramines such as 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, Jeffamine® SD-2001, Jeffamine® D-205, and Jeffamine® RFD-270.

[0050] In one embodiment, the crosslinking precursor may include an aromatic primary diamine such as m-xylylenediamine and a p-xylylenediamine.

[0051] In one embodiment, examples of crosslinking precursors include aliphatic primary diamines, such as 1,2-diaminoethane, 1,6-diaminohexane, 1,4-diaminobutane, 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, isophoronediamine, bicyclo[2.2.2]octane-1,4-diamine, and combinations thereof. Other aliphatic diamines suitable for carrying out the present invention include those having 6 to 12 carbon atoms, or combinations of long-chain and short-chain diamines or alicyclic diamines.

[0052] In one embodiment, examples of crosslinking precursors include secondary amines such as piperazine, N,N'-diisopropylethylenediamine, N,N'-diisopropyl-1,3-propanediamine, and N,N'-dimethyl-1,3-propanediamine, as well as triamines such as 2,4,6-triaminopyrimidine (TAP), melamine, diethylenetriamine, Jeffamine® T-403, Jeffamine® T-3000, and Jeffamine® T-5000. In addition, as mentioned above, many diamines that can be used as diamine monomers for polymers may also be useful as crosslinking precursors.

[0053] In one embodiment, the crosslinking precursor may contain one or more amine groups, each of which is either reactive or inactive to crosslinking the polymer. If it contains inactive amine groups, the crosslinking precursor can then be chemically converted, thermally converted, photoconverted, or dissociated to form at least two reactive amines.

[0054] In one embodiment, the crosslinking precursor may include alkyl chains such as methyl and tert-butyl chains as deactivating groups such as N-alkyl or N,N-dialkyl chains. In one embodiment, the crosslinking precursor may include aromatic deactivating groups such as N-aryl and N,N-diaryl groups. In one embodiment, the crosslinking precursor may be a compound containing a benzyl deactivating group. In one embodiment, the crosslinking precursor may be a compound containing a silyl derivative such as tert-butyldiphenylsilyl as the deactivating group. Many functional groups can function as amine protecting groups for soluble polymers having imide groups. See, for example, Non-Patent Literature 1 ("Greene's").

[0055] In one embodiment, the crosslinking precursor may include a carbamate as an inactivating group. The carbamate inactivating group can be converted in various ways to form a reactive amine. Many carbamates can typically be converted to form a reactive amine by heating at temperatures above 150°C. Various chemical routes can also be used to convert the carbamate functional group to form a reactive amine. For example, the introduction of a base such as tert-butyl alcohol or an acid such as phosphoric acid or trifluoroacetic acid can be used to convert the carbamate to form a reactive amine. Photo-induced reactions can also be used to cleave the carbamate and form a reactive amine. Various methods for converting various carbamates are described in Greene's. In one embodiment, the crosslinking precursor may be a compound containing a thermally cleavable carbamate inactivating group such as tert-butyloxycarbonyl, fluorenylmethoxycarbonyl, and benzylcarbamate, or a compound containing a photocleavable carbamate inactivating group such as 3,5-dimethoxybenzylcarbamate, m-nitrophenylcarbamate, and bi-o-nitrobenzylcarbamate.

[0056] In one embodiment, the crosslinking precursor includes an amide deactivating group that can be cleaved by the introduction of a different chemical species to form a reactive amine. For example, the different chemical species may include a base such as sodium hydroxide or potassium hydroxide, ammonia, or a tertiary amine. In another example, an acid such as hydrochloric acid or an enzyme such as penicillin acylase or α-chymotrypsin can be used to cleave the amide and form a reactive amine.

[0057] In one embodiment, the crosslinking precursor containing an amide-deactivating group can be photocleaved by irradiation with 245 nm light or by thermal cleavage at a temperature above 65°C. A wide range of amides, such as those described in Greene's, can be used as the crosslinking precursor. In one embodiment, the crosslinking precursor may be a compound containing an amide-deactivating group, such as acetamide, trifluoroacetamide, formamide, sulfonamide, for example, p-toluenesulfonamide, trichloroacetamide, chloroacetamide, phenylacetamide, 3-phenylpropanamide, 3-pyridylcarboxamide, N-benzoylphenylalanyl, and benzamide.

[0058] In one embodiment, the crosslinking precursor may be an ammonium salt prepared from an acid such as acetic acid, butyric acid, pivalic acid, hydrochloric acid, or sulfuric acid. Ammonium salts that can be used to inactivate amines in the crosslinking precursor can be formed by the addition of organic and / or inorganic Brønsted acids. The ammonium salt is formed by a direct reaction between the acid and the crosslinking precursor containing the amine. The ammonium salt can be dissociated by heating to enable crosslinking. Kinetic inhibition is also controlled by the acid-ammonium equilibrium constant. If there is insufficient acid in the solution, as determined by the acid-ammonium equilibrium constant, the ammonium salt may dissociate to form a reactive amine in the crosslinking precursor. In one embodiment, the ammonium salt can be prepared from the reaction of an amine with acetic acid or trifluoroacetic acid, which can then be dissociated by heating.

[0059] In one embodiment, the crosslinking precursor is selected from a single polyfunctional precursor, a combination of multiple monofunctional precursors, or a mixture thereof.

[0060] Coloring agents In one embodiment, the polymer film contains about 1 to about 40% by weight of a colorant, such as a pigment or dye. In some embodiments, the polymer film contains about 1 to about 40% by weight of a mixture of pigments and dyes. In some embodiments, the polymer film contains any two of the following, but in between: 1, 5, 10, 15, 20, 25, 30, 35, and 40% by weight of a colorant.

[0061] In effect, any pigment (or combination of pigments) can be used in the implementation of the present invention. In some embodiments, useful pigments include, but are not limited to, barium lemon yellow, cadmium yellow lemon, 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.

[0062] 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.

[0063] 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.

[0064] 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, but is not limited to, vat dye pigments such as perylene, perylene black, perinone, or thioindigo. A homogeneous dispersion of isolated individual pigment particles (aggregates) tends to produce a 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 (optionally including them): 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 glossy pigments can be used alone or in combination with other pigments or dyes.

[0065] In one embodiment, the colorant may include low conductivity carbon black. In some embodiments, the colorant includes any two of the following, but in between: 1, 5, 10, 15, and 20% by weight of low conductivity carbon black. In yet another embodiment, the colorant includes about 2 to about 9% by weight of low conductivity carbon black.

[0066] 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 way to assess the extent of surface oxidation (of carbon black) is to measure the heat loss of the carbon black. Heat loss can be measured by calculating the weight loss when calcined at 950°C for 7 minutes. Generally, highly surface-oxidized carbon black (high heat loss) is readily dispersible in a polymer precursor solution, which can then be imidized into the (well-dispersed) packed 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 usually suppressed, resulting in low conductivity. In some embodiments, low conductivity carbon black has a heat loss of 1% or more. In some embodiments, low conductivity carbon black has a heat loss of 5, 9, or 13% or more. In some embodiments, furnace black may be surface-treated to increase the heat loss. Typically, low conductivity carbon black has a pH of less than about 6.

[0067] A homogeneous dispersion of isolated carbon black particles (aggregates) not only reduces conductivity but also tends to produce a uniform color intensity. In some embodiments, low-conductivity carbon black is milled. In some embodiments, the average particle size of the low-conductivity carbon black includes (optionally including) any two of the following sizes: 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 μm.

[0068] Matting agent In one embodiment, the polymer film contains about 0.5 to about 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 polymer film contains any two of the following, including between: 0.5, 1, 5, 10, 15, and 20% by weight of the matting agent. In one embodiment, the matting agent has a particle size in the range of about 2 to about 10 μm, or about 3 to about 9 μm, or about 5 to about 7 μm.

[0069] Submicron particles In one embodiment, the polymer film contains at least one submicron particle, 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, up to about 39% by weight. In some embodiments, the submicron fumed metal oxide is fumed alumina, fumed silica, or a mixture thereof. In one embodiment, the polymer film contains at least one submicron particle, up to about 20% by weight or up to about 10% by weight. 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 about 0.01 to about 1 μm or about 0.05 to about 0.5 μm.

[0070] 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, because submicron particles tend to aggregate, it may be more accurate to measure the particle size of these ground slurries by observing them with an optical microscope.

[0071] polymer film In one embodiment, a polymer film can be produced by mixing a diamine and a dianhydride (in monomer or other polymer precursor form) with a solvent to form a polyamic acid (also called polyamide acid) solution. The dianhydride and diamine can be combined in a molar ratio of about 0.90 to 1.10. The molecular weight of the polyamic acid formed therefrom can be adjusted by adjusting the molar ratio of the dianhydride to the diamine.

[0072] Useful methods for producing polyamic acid solutions according to the present invention can be found in (Patent Document 1) and (Patent Document 2), all teachings therein are incorporated herein by reference. Numerous variations are also possible, as follows: (a) A method in which the diamine component and the dianhydride component are mixed together beforehand, and then gradually added to the solvent while the mixture is being stirred. (b) A method in which the solvent is added to a stirred mixture of the diamine component and the dianhydride component. (Conversely to (a) above) (c) A method in which a diamine is exclusively dissolved in a solvent, and then a dianhydride is added thereto in a ratio that allows control of the reaction rate. (d) A method in which a dianhydride component is exclusively dissolved in a solvent, and then an amine component is added thereto in a ratio that allows control of the reaction rate. (e) A method in which the diamine component and the dianhydride component are dissolved separately in a solvent, and then these solutions are mixed in a reactor. (f) A method in which a polyamic acid containing an excess amine component and another polyamic acid containing an excess dianhydride component are formed in advance and then reacted with each other in a reactor in a manner that particularly allows for the formation of a non-random copolymer or a block copolymer. (g) A specific portion of the amine component and the dianhydride component is reacted first, followed by the reaction of the residual diamine component, or vice versa. (h) A method in which components are added partially or entirely to any part or all of a solvent in any order, and any part or all of any component may also be added as a solution to part or all of the solvent. (i) A method in which one of the dianhydride components is first reacted with one of the diamine components to produce a first polyamic acid. Then, another dianhydride component is reacted with another amine component to obtain a second polyamic acid. Subsequently, the amic acid is bonded by one of several methods before imidization.

[0073] In one embodiment, a polyamic acid solution can be combined with the following conversion chemicals: (i) one or more dehydrating agents such as aliphatic anhydrides and / or aromatic anhydrides (e.g., acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride); and (ii) one or more catalysts such as aliphatic tertiary amines (e.g., triethylamine), aromatic tertiary amines (e.g., dimethylaniline), and heterocyclic tertiary amines (e.g., pyridine, alpha, beta, and gamma picolines (2-methylpyridine, 3-methylpyridine, 4-methylpyridine), isoquinoline). The dehydrating agent, which is an anhydride, is often used in molar excess compared to the amount of amidic acid groups in the polyamic acid. The amount of acetic anhydride used is typically about 2.0 to 4.0 moles per equivalent (repeating unit) of polyamic acid. Generally, an equivalent amount of the tertiary amine catalyst is used.

[0074] In one embodiment, the conversion chemical may be an imidation catalyst (sometimes called an "imidation accelerator") that can promote a decrease in imidation temperature and a reduction in imidation time. Typical imidation catalysts may range from imidazole, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, benzimidazole, isoquinoline, substituted pyridines (such as methylpyridine, lutidine, and trialkylamines), and bases such as hydroxy acids (such as isomers of hydroxybenzoic acid). The ratio and concentration of these catalysts in the polyamic acid layer affect the reaction rate of imidation and the properties of the film.

[0075] 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 into a polymer having imide groups. Temperature, time, and the concentration and selection of the imidation catalyst may affect the degree of imidization of the polyamic acid solution. Preferably, the solution should be fully imidized. In one embodiment, in a fully polymerized solution, more than 85%, more than 90%, or more than 95% of the amic acid groups are converted into a polymer having imide groups, as determined by infrared spectroscopy.

[0076] In one embodiment, a solvation mixture (a well-imidized solution) can be cast to form a polymer film. In another embodiment, the solvation mixture (the first well-imidized solution) can be precipitated using a poor solvent such as water or alcohol (e.g., methanol, ethanol, isopropyl alcohol) to isolate a solid polymer resin. For example, isolation can be performed by filtration, decantation, centrifugation and decantation of the supernatant, distillation in the vapor phase or solvent removal, 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 thoroughly dried, but does not need to be completely dry. The polymer 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 well-imidized solution (casting solution), which can be cast to form a polymer film.

[0077] In one embodiment, the well-polymerized solution is formed using monomers (diamines or dianhydrides) having structural properties important to solubility, including but not limited to aliphatic spacers, ethers, thioethers, substituted amines, amides, esters, and ketones, weak intermolecular interactions, bulky substituents, non-resonant, nonlinear, and asymmetric flexible bonding. Examples of diamines incorporating some of these properties include aliphatic diamines such as HMD, CHDA, and IPDA, and aromatic diamines such as MTB TFMB, MPD, RODA, BAPP, and 3,4-ODA. Examples of dianhydrides incorporating some of these properties include 6FDA, BPADA, ODPA, DSDA, and BODA.

[0078] In one embodiment, a solvation mixture (a well-imidized solution) can be mixed with a crosslinking precursor and a colorant such as a pigment or dye, and then cast to form a polymer film. In one embodiment, the colorant may be low-conductivity carbon black. In another embodiment, the solvation mixture (the first well-imidized solution) can be precipitated in a poor solvent such as water or alcohol (e.g., methanol, ethanol, isopropyl alcohol). In one embodiment, the precipitate can be washed to remove the catalyst. After washing, the precipitate can be thoroughly dried, but does not need to be completely dry. The polymer precipitate can be redissolved in a second solvent such as methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), tetrahydrofuran (THF), cyclopentanone, ethyl acetate, acetone, DMAc, NMP, and mixtures thereof to form a second well-imidized solution (casting solution). A crosslinking precursor and a colorant can be added to the second well-imidized solution, and then cast to form a polymer film. In one embodiment, the polymer film contains about 80 to about 99% by weight of the crosslinked polymer. In some embodiments, the polymer film includes any two of the following, and between them: 80, 85, 90, 95, and 99% by weight of the crosslinked polymer. In yet another embodiment, the polymer film contains about 91 to about 98% by weight of the crosslinked polymer.

[0079] In one embodiment, poly(amide-imide) can be formed by the reaction of acyl chloride with a diamine and an anhydride.

[0080] In one embodiment, poly(ester-imide) or poly(amide-imide) can be formed using an ester or amide-containing diamine or dianhydride in a process similar to that described above. In one embodiment, poly(ester-imide) can be formed by the direct reaction of an ester-containing diamine or dianhydride. In one embodiment, poly(amide-imide) can be formed by the direct reaction of an amide-containing diamine or dianhydride.

[0081] In one embodiment, poly(ester-imide) can be formed by esterifying a diol with a carboxylic acid containing a monomer having an imide group, as described in (Patent Document 3).

[0082] Polymer crosslinking can be determined by various methods. In one embodiment, the gel fraction of the polymer can be determined by comparing the weights of the dried film before and after crosslinking and using an equilibrium swelling method. In one embodiment, the crosslinked polymer can have a gel fraction in the range of about 20 to about 100%, or about 40 to about 100%, or about 50 to about 100%, or about 70 to about 100%, or about 85 to about 100%. In one embodiment, the crosslinked network can be identified using a rheological method. Vibration time sweep measurements at specific strains, frequencies, and temperatures can be used to confirm the formation of the crosslinked network. Initially, the loss modulus (G'') value is higher than the storage modulus (G') value, indicating that the polymer solution behaves like a viscous liquid. Over time, the formation of the crosslinked polymer network is demonstrated by the intersection of the G' and G'' curves. The intersection, called the "gel point," represents the point where the elastic component is dominant over the viscous component.

[0083] The casting solution may further contain one of a number of additives, such as processing aids (e.g., oligomers), antioxidants, light stabilizers, flame retardant additives, 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, and conductive fillers such as metals. Common inorganic fillers include alumina, silica, diamond, clay, talc, sepiolite, boron nitride, aluminum nitride, titanium dioxide, dicalcium phosphate, and fumed metal oxides. Low-coloring organic fillers such as polydialkylfluorene can also be used.

[0084] In one embodiment, the conductive filler is carbon black. In one embodiment, the conductive filler is selected from the group consisting of acetylene black, ultra-abrasive furnace black, conductive furnace black, conductive channel-type black, carbon nanotubes, carbon fibers, fine thermal black, and mixtures thereof. As previously mentioned for low-conductivity carbon black, the oxygen composite on the surface of the carbon particles functions as an electrical insulating layer. Therefore, low-volatility components are usually desirable for high conductivity. However, the difficulty of dispersing carbon black must also be considered. Surface oxidation promotes the deaggregation and dispersion of carbon black. In some embodiments, when the conductive filler is carbon black, the carbon black has 1% or less of volatile components.

[0085] The 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 nm, less than 450 nm, less than 400 nm, less than 350 nm, less than 300 nm, less than 250 nm, or less than 200 nm (the filler can take various shapes in any dimension, and the shape of the filler can 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 or greater. 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. In one embodiment, the submicron filler of the present disclosure exhibits an aspect ratio of at least 1, at least 2, at least 4, at least 6, at least 8, at least 10, at least 12, or at least 15 to 1.

[0086] In some embodiments, the size of the submicron fillers is 100 nm or less. In some embodiments, the fillers are spherical or elliptical in shape and are nanoparticles. In one embodiment, examples of submicron fillers include inorganic oxides such as silicon, aluminum, and titanium oxides, hollow (porous) silicon oxides, antimony oxides, zirconium oxides, indium tin oxides, antimony tin oxides, 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 multiple core / shell structures) may be used in which one oxide encapsulates another oxide within a single particle.

[0087] 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, silicon carbide, and combinations thereof, or higher-order compounds containing multiple cations and multiple anions.

[0088] In one embodiment, solid silicon oxide nanoparticles can be prepared from silicon oxide sols (e.g., colloidal dispersions of solid silicon oxide nanoparticles in a liquid medium), particularly sols of amorphous, semicrystalline, and / or crystalline silica. Such sols can be prepared by various methods in various forms, such as 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 contains both water and an organic liquid). See, for example, the descriptions of techniques and embodiments disclosed in (Patent Document 4), (Patent Document 5), and (Patent Document 6). In one embodiment, the nanoparticles are suspended in a polar, aprotic solvent, such as DMAC or other solvents compatible with polyamic acid or poly(amidoamic acid). In another embodiment, solid nanosilica particles are prepared, for example, DMAC-ST (Nissan Chemical America Corporation, Houston TX), containing less than 0.5 percent water and 20-21 wt% SiO2, with a median diameter d of the nanosilica particles. 50 It can be commercially obtained as a colloidal dispersion or sol dispersed in a polar aprotic solvent, such as a solid silica colloid in dimethylacetamide, with a wavelength of approximately 16 nm.

[0089] In one embodiment, submicron fillers can be porous and may have pores of any shape. One example is when the pores contain low-density, low-refractive-index voids (e.g., voids containing air) formed within an oxide shell, such as silicon oxide, i.e., hollow silicon oxide nanoparticles. The thickness of the shell of a submicron filler affects its strength. Hollow silicon oxide particles have a lower refractive index and a higher porosity, thus reducing the shell thickness and decreasing the strength (i.e., fracture resistance) of the submicron filler. Methods for producing such hollow silicon oxide nanoparticles are known, for example, as described in (Patent Document 7) and (Patent Document 8). Hollow silicon oxide nanoparticles are available from JGC Catalysts & Chemicals Ltd. in Japan.

[0090] In one embodiment, the submicron filler may be coated with a coupling agent. For example, the nanoparticles may be coated with an acrylic or methacrylic coupling agent derived from aminosilane, phenylsilane, or the corresponding alkoxysilane. A trimethylsilyl surface capping agent may be introduced to the nanoparticle surface by reaction of the submicron filler with hexamethyldisilazane. In one embodiment, the submicron filler may be coated with a dispersant. In one embodiment, the submicron filler may be coated with a combination of a coupling agent and a dispersant. Alternatively, the coupling agent, dispersant, or a combination thereof may be incorporated directly into the polyimide film and do not necessarily need to be coated on the submicron filler.

[0091] In one embodiment, a well-imidized polymer solution may be cast or coated onto a support such as an endless belt or a rotating drum to form a film. Alternatively, it may 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 may 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 peeled from the support before it is completely dry. The final drying step may be carried out along with dimensional support or stabilization of the film. In other embodiments, the film is heated directly on the support.

[0092] The thickness of the polymer film can be adjusted according to the intended purpose or end-use specifications of the film. In one embodiment, the polymer film has a total thickness in the range of about 10 to about 150 μm, or about 10 to about 100 μm, or about 25 to about 80 μm.

[0093] In one embodiment, the polymer film has a b* of less than about 1.25, less than about 1.0, or less than about 0.8 when measured in total transmission mode over the wavelength range of 360–780 nm using a dual-beam spectrophotometer with D65 illumination and a 10° observer, for a film thickness of about 50 μm. In one embodiment, the polymer film has a yellowness (YI) of less than about 2.25, less than about 2.0, or less than about 1.75 when measured using the procedure described in ASTM E313, for a film thickness of about 50 μm.

[0094] Purpose In one embodiment, the polymer film can be used in electronic device applications such as coverlays for printed circuit boards or other electronic components within electronic devices, providing protection from physical damage, oxidation, and other contaminants that may adversely affect the function of the electronic components. Very fine coverlays of polymer films using crosslinked polymers can have higher chemical resistance and etching resistance during processing used in circuit manufacturing while maintaining good optical properties.

[0095] In one embodiment, a polymer film that can be patterned by light can be used as a dielectric for electronic circuit applications. For example, after forming the polymer film, a light-shielding mask can be used to expose the polymer film in a desired pattern, and the exposed portions of the film are photocrosslinked by irradiating the photosensitive polymer with light. The resulting polymer film then has a large difference in solubility between the exposed (crosslinked) regions and the unexposed regions of the film, allowing for easy removal of the unexposed regions.

[0096] In one embodiment, polymer films can be used for many layers in organic electronic devices. Non-limiting examples of such layers include device substrates, touch panels, substrates for color filter sheets, and cover films. The specific material properties required for each application are unique and can be addressed by suitable compositions and processing conditions for the polymer films disclosed herein. Organic electronic devices that may benefit from having coated films 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, luminaires, or diode lasers), (2) devices that detect signals by electronic processes (e.g., photodetectors, photoconductive cells, photoresistors, photoswitches, phototransistors, phototubes, 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).

[0097] 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]

[0098] Test method Gel fraction The gel fraction of the polymer was measured using the equilibrium swelling method. The polymer film was cast from the solution and dried on a hot plate at 80°C for 20–25 minutes. The film was then further dried in an oven heated from 120 to 250°C (16°C / min), followed by holding at 250°C for 20 minutes. After cooling, a portion of the film's mass (typically 0.1–0.5 g) was weighed and immersed in approximately 100 ml of DMAc. The film was stored in DMAc for 3–5 days, with the DMAc being replaced daily. The film was then removed from the DMAc solution and dried on a hot plate at 80°C for 10 minutes, followed by further drying in an oven according to the same heating profile (heating from 120–250°C, then holding at 250°C for 20 minutes). The film was then weighed again for its final mass. The difference represented the gel fraction.

[0099] Comparative Example 1 For Comparative Example 1 (CE1), a DMAc solution of polyimide with a monomer composition of CBDA 0.6 / 6FDA 0.4 / / TFMB 1.0 was used in film production. In CE1, to remove gas from the polymer, 50 g of a 9.6 wt% polymer solution was degassed using a centrifugal planetary mixer (THINKY USA, Laguna Hills, CA) at 2000 rpm for 10 minutes.

[0100] A 1-2 mil cured film was produced by casting the solution onto a glass substrate at 25°C. The film on the glass substrate was heated to 80°C for 10 minutes, then lifted from the glass surface and mounted on an 8 x 12 inch pin frame. The mounted film was placed in a furnace. The furnace was heated from 120°C to 250°C (16°C / min), and then held at 250°C for 20 minutes. After heating at 250°C for 20 minutes, the film was removed from the furnace at "high temperature" and allowed to cool in the air.

[0101] Example 1 For Example 1 (E1), a DMAc solution of polyimide with a monomer composition of CBDA 0.6 / 6FDA 0.4 / / TFMB 1.0 was used in film production. In E1, 3.55 g of 10 wt% trans-N-boc-1,4-cyclohexanediamine (boc-CHDA) in the DMAc was added to 50 g of a 9.6 wt% polymer solution and mixed using a centrifugal planetary mixer at 2200 rpm for 2 minutes. Subsequently, the solution was degassed using a centrifugal planetary mixer at 2000 rpm for 10 minutes to expel gas from the polymer.

[0102] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil film for CE1 as described above.

[0103] Example 2 For Example 2 (E2), a DMAc solution of polyimide with a monomer composition of CBDA 0.6 / 6FDA 0.4 / / TFMB 1.0 was used in film production. In E2, 7.1 g of 20% by weight of boc-CHDA in the DMAc was added to 50 g of a 9.6% by weight polymer solution and mixed using a centrifugal planetary mixer at 2200 rpm for 2 minutes. Subsequently, the solution was degassed using a centrifugal planetary mixer at 2000 rpm for 10 minutes to expel gas from the polymer.

[0104] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil film for CE1 as described above.

[0105] Example 3 For Example 3 (E3), a DMAc solution of polyimide with a monomer composition of CBDA 0.6 / 6FDA 0.4 / / TFMB 1.0 was used in film production. To first remove gas from the polymer, degassing was performed using a centrifugal planetary mixer at 2000 rpm for 10 minutes. In E3, 1.89 g of a solution containing 10 wt% 1,4-cyclohexanediamine (CHDA), 4.5 wt% acetic acid, and 85.5 wt% DMAc was added to 50 g of a 9.6 wt% polymer solution, and this was mixed using a centrifugal planetary mixer at 2200 rpm for 30 seconds.

[0106] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil film for CE1 as described above.

[0107] Comparative Example 2 For Comparative Example 2 (CE2), a DMAc solution of polyimide with a monomer composition of CBDA 0.6 / 6 FDA 0.4 / / TFMB 1.0 was used in film production. To first remove gas from the polymer, degassing was performed using a centrifugal planetary mixer at 2000 rpm for 10 minutes. In CE2, 1.89 g of a solution containing 10 wt% CHDA, 6.6 wt% acetic acid, and 83.4 wt% DMAc was added to 50 g of a 9.6 wt% polymer solution, and this was mixed using a centrifugal planetary mixer at 2200 rpm for 30 seconds.

[0108] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil film for CE1 as described above.

[0109] Example 4 For Example 4 (E4), a soluble thermoplastic polyimide (Matrimid® 9725, Huntsman Corp., The Woodlands, TX) with a monomer composition of 3,3',4,4'-benzophenonetetracarboxylic dianhydride / / 3-(4-aminophenyl)-1,1,3-trimethyl-5-indanamine (BTDA 1.0 / / PIDA 1.0) was used as a dry powder.

[0110] In E4, 2.5 g of dry polymer resin was added to 9.73 g of DMAc and mixed in a centrifugal planetary mixer to obtain a solution. To remove gas from the polymer, the solution was degassed using a centrifugal planetary mixer at 2000 rpm for 10 minutes. 0.52 g of a solution containing 9.75 wt% HMD and 7.60 wt% acetic acid in DMAc was added to the polyimide solution. This solution was mixed using a centrifugal planetary mixer at 2200 rpm for 30 seconds.

[0111] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil cured film. The film on the glass substrate was heated to 90°C for 25 minutes, then lifted from the glass surface and mounted on an 8 x 12 inch pin frame. The mounted film was placed in a furnace and heated according to the heating profile described above for CE1.

[0112] Example 5 In Example 5 (E5), a soluble thermoplastic polyimide (Ultem® 1000, GE Plastics, Boston, MA) with a monomer composition of 4,4'-bisphenol A dianhydride / / p-phenylenediamine (BPADA 1.0 / / PPD 1.0) was used as a dry powder.

[0113] In E5, 2.5 g of dry polymer resin was added to 9.51 g of DMAc and mixed in a centrifugal planetary mixer to obtain a solution. To remove gas from the polymer, the solution was degassed using a centrifugal planetary mixer at 2000 rpm for 10 minutes. 0.49 g of a solution containing 9.75 wt% HMD and 7.60 wt% acetic acid in DMAc was added to the polyimide solution. This solution was mixed using a centrifugal planetary mixer at 2200 rpm for 30 seconds.

[0114] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil film for E4 as described above.

[0115] Example 6 For Example 6(E6), a soluble polyimide with a monomer composition of 6FDA 1.0 / / TFMB 0.75 / HMD 0.25 was used as a dry powder. TFMB and HMD were dissolved in DMAc and heated to 40°C. Then, 6FDA was added and reacted overnight at 40°C. To obtain a well-imidized solution, 4.0 molar equivalents of beta-picoline and 4.0 molar equivalents of acetic anhydride were added to the poly(amitic acid) solution. Next, this mixture was stirred at 45°C for 18 hours, then cooled to room temperature, precipitated, and washed with methanol. The resulting polyimide powder was vacuum-dried at 50°C until it reached a certain weight.

[0116] In E6, 2.5 g of dry polymer resin was added to 9.57 g of DMAc and mixed in a centrifugal planetary mixer to obtain a solution. To remove gas from the polymer, the solution was degassed using a centrifugal planetary mixer at 2000 rpm for 10 minutes. 0.43 g of a solution containing 9.75 wt% HMD and 7.60 wt% acetic acid in DMAc was added to the polyimide solution. This solution was mixed using a centrifugal planetary mixer at 2200 rpm for 30 seconds.

[0117] The solution was cast onto a glass substrate at 25°C to produce a 1-2 mil film for E4 as described above.

[0118] Table 1 summarizes Examples 1-6 and Comparative Examples 1 and 2.

[0119] [Table 1]

[0120] Example 7 For Example 7 (E7), to prepare a polymer having the composition 6FDA 0.2 / BPDA 0.3 / TCP 0.5 / TFMB 1.0, 32.0213 g of TFMB was added to a nitrogen-purged 1 L resin kettle along with 384.5 g of DMAc. 8.8932 g of biphenyltetracarboxylic dianhydride (BPDA) and 8.8953 g of 6FDA were added. 10.1510 g of terephthaloyl chloride (TCP, Sigma Aldrich) was added in 1 / 3 increments to form the final solution.

[0121] 396.96 g of polyamide-amic acid solution was used, and 200 ml of DMAc was added to the solution. The reaction mixture was heated to 40°C with stirring. 26.85 g of acetic anhydride and 24.49 g of beta-picoline were combined and then slowly added to the polyamide-amic acid solution over 30 minutes using a dropping funnel. The reaction mixture was heated to 80°C, stirred for 2 hours, and then allowed to cool to room temperature for 12 hours.

[0122] The reaction mixture was poured into excess water to precipitate the resin, which was then pulverized in a blender and recovered by filtration. The precipitated solid was thoroughly washed with methanol. The polymer was dried under vacuum at 25°C for approximately 16 hours to form the final resin.

[0123] 3.50 g of resin was dissolved in 31.45 g of DMAc along with 0.166 g of N-Boc-1,6-hexanediamine. The mixture was stirred using a centrifugal planetary mixer for two 8-minute cycles. The final formulation was prepared by filtering this material through a 10 μm filter medium, mixing again, and filtering again.

[0124] The solution was cast onto a glass substrate at 25°C to produce a film of approximately 2 mils. Using a doctor blade with a 40 mm clearance, the coating solution of the composition was cast onto a glass substrate at 25°C, and after curing, a film of approximately 2 mils was produced. The film on the glass substrate was heated on a hot plate at 50°C for 30 minutes, then at 90°C for 30 minutes. The film was allowed to cool to room temperature. The coating was placed on a hot plate and heated in air at 50°C for 30 minutes, then at 80°C for 30 minutes. The film was peeled off using a razor, mounted on a 4 x 8 inch pin frame, and placed in a furnace (Carbolite Gero, Sheffield, UK). The furnace was then purged with nitrogen and heated according to the following temperature protocol: From 25°C to 90°C (7°C / min), hold at 45°C for 5 minutes; From 90°C to 150°C (7°C / min), hold at 150°C for 10 minutes; Heat from 150°C to 250°C (7°C / min), then maintain at 250°C for 20 minutes.

[0125] After heating to 250°C for 20 minutes, the film was removed from the furnace and allowed to cool in the air.

[0126] The gel fraction of the film was 95.5% by weight. After immersion in DMAc for 5 days, the film did not dissolve very well.

[0127] Comparative Example 3 For Comparative Example 3 (CE3), the procedure of E7 was used, except that N-Boc-1,6-hexanediamine was not added to the coating formulation. This polymer was soluble in DMAc (gel fraction = 0%).

[0128] Table 2 summarizes Example 7 and Comparative Example 3.

[0129] [Table 2]

[0130] It should be noted that not all of the actions described above are required in general descriptions, some of the actions may not be necessary, and additional actions may be performed in addition to those described. Furthermore, the order in which the actions 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 actions can be used for their specific needs or desires.

[0131] 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 alterations can be made without departing from the scope of the invention as set forth in the following claims. All features disclosed herein may be replaced by alternative features that serve the same, equivalent, or similar purposes. Accordingly, this specification should be considered illustrative rather than restrictive, and all such alterations are intended to be included within the scope of the invention.

[0132] The benefits, advantages, and solutions to problems relating to specific embodiments have been described above. However, these benefits, advantages, solutions to problems, and any elements that may give rise to or make more prominent any benefits, advantages, or solutions should not be construed as essential, necessary, or intrinsic features or elements of any or all of the claims.

Claims

1. A coating solution, Soluble polymers containing imide groups, and A crosslinking precursor, A first amine group that is either reactive to or inactivated by crosslinking, The crosslinking precursor is inactivated for crosslinking by one or more additional amine groups so that it can be chemically converted, thermally converted, photoconverted, or dissociated to form at least two reactive amines. Includes cross-linking precursor A coating solution containing [the specified ingredient].

2. The coating solution according to claim 1, wherein the one or more additional amine groups are inactivated to form a site selected from the group consisting of carbamates, N-alkylamines, N,N-dialkylamines, N-arylamines, N,N-diarylamines, benzylamines, amides, sulfonamides, ammonium salts produced from acids, and silyl derivatives.

3. The coating solution according to claim 2, wherein the carbamate is thermally cleavable.

4. The coating solution according to claim 3, wherein the thermally cleavable carbamate is selected from the group consisting of tert-butyloxycarbonyl, fluorenylmethoxycarbonyl, and benzylcarbamate.

5. The coating solution according to claim 2, wherein the carbamate is photocleavable, and the photocleavable carbamate is selected from the group consisting of 3,5-dimethoxybenzylcarbamate, m-nitrophenylcarbamate, and o-nitrobenzylcarbamate.

6. The coating solution according to claim 2, wherein the amide is selected from the group consisting of formamide, trifluoroacetamide, trichloroacetamide, chloroacetamide, phenylacetamide, 3-phenylpropanamide, 3-pyridylcarboxamide, N-benzoylphenylalanyl, and benzamide.

7. The coating solution according to claim 2, wherein the amide may be thermally cleaved, chemically cleaved, photocleaved, dissociated, or a mixture thereof.

8. Ammonium salts are produced from acids selected from the group consisting of acetic acid, butyric acid, pivalic acid, hydrochloric acid, and sulfuric acid, and The coating solution according to claim 2, wherein the ammonium salt can be thermally dissociated to form a reactive amine.

9. The coating solution according to claim 1, wherein the crosslinking precursor is selected from a single polyfunctional precursor, a combination of multiple monofunctional precursors, or a mixture thereof.

10. The coating solution according to claim 1, wherein the soluble polymer is selected from the group consisting of polyimide, poly(amide-imide), poly(ether-imide), poly(ester-imide), amide, ester, or copolymers containing ether groups, and mixtures thereof.

11. The coating solution according to claim 1, further comprising a filler selected from the group consisting of nanoparticles, colorants, matting agents, submicron particles, thermally conductive fillers, conductive fillers, and mixtures thereof.

12. The coating solution according to claim 11, wherein the coloring agent comprises low-conductivity carbon black.

13. A method for forming a polymer film, (a) Casting a coating solution, wherein the coating solution is Soluble polymers containing imide groups, and A crosslinking precursor, A first amine group that is either reactive to or inactivated by crosslinking, The crosslinking precursor is inactivated for crosslinking by one or more additional amine groups such that it can be chemically cleaved, thermally cleaved, photocleaved, or dissociated to form at least two reactive amines. Includes cross-linking precursor Casting, (b) Activating the crosslinking precursor using an external stimulus to form at least two reactive amines and crosslinking the polymer, (c) Drying the polymer film A method that includes this.

14. The method according to claim 13, wherein the external stimulus is heat, light, or a different chemical species.