Abstract: Novel polyimides substituted by a substituent having an alkyl or fluoroalkyl group and having reduced water absorption; a process for producing these novel polyimides; and novel acid dianhydrides to be used in the production thereof. A polyimide containing a structure represented by the following general formula (I): wherein X1 represents a tetravalent organic group having a substituent —R1AR2 (wherein A represents a divalent linkage group; R1 represents a single bond or a C1-3 alkylene group; and R2 represents a C1-25 alkyl group or a fluoroalkyl group); and Y represents a divalent organic group.

Abstract: In a photoconductive element comprising a conductive support, e.g., an electrically conductive film, drum or belt on which a negatively chargeable photoconductive layer is formed, an electrical barrier layer is formed between the support and the photoconductive layer. The barrier layer provides a high energy barrier to the injection of positive charges but transports electrons under an applied electric field. The barrier layer of the invention transports charge by electronic rather than ionic mechanisms and, therefore, is not substantially affected by humidity changes.

Abstract: A novel modified polyimide resin having a polybutadiene sheleton and obtainable by reacting the following three (3) kinds of compounds, i.e., a bifunctional hydroxyl-terminal polybutadiene having a number average molecular weight of 800 to 5,000, a tetrabasic acid dianhydride, and a diisocyanate compound, imparts reduced shrinkage upon setting to a thermosetting resin composition comprising the same and also imparts heat resistance and pliability and the like to a hardened mass or article of such thermosetting resin composition. Therefore, such thermosetting resin composition is an excellent resin composition capable of fully satisfying the requirements with regard to the characteristics of an overcoat agent for a wiring circuit which should be pliable, such as a flexible wiring circuit substrate, a film carrier and the like.

Abstract: A primary object of the invention is to provide a production technology for functional polyamic acid microfine particles and functional polyimide microfine particles by which the particle shape, size and size distribution can be freely controlled. The invention is concerned with a process for synthesizing polyamic acid particles having functional groups at least on the surface from a tetracarboxylic anhydride and a diamine compound characterized by its comprising (a) a first step which comprises providing a tetracarboxylic anhydride and a diamine compound at least one of which has functional groups and preparing a first solution containing the tetracarboxylic anhydride and a second solution containing the diamine compound and (b) a second step which comprises mixing the first and second solutions under ultrasonic agitation to thereby precipitate polyamic acid microfine particles from the mixed solution.

Abstract: A polyimide film, which is produced from polyamide acid prepared through the reaction of p-phenylenebis(trimellitic acid monoester anhydride), oxydiphthalic acid dianhydride, p-phenylenediamine, and 4,4′-diaminodiphenylether in an organic solvent, and which has a high elastic modulus, a high elongation, a low coefficient of linear expansion which is not quite different from that of copper, and a low coefficient of hygroscopic expansion.

Abstract: An object of the invention is to provide thermosetting amic acid microfine particles, thermosetting imide microfine particles and crosslinked imide microfine particles of controlled particle shape and size distribution. The invention provides a production technology which comprises mixing a first solution containing a tetracarboxylic anhydride and a C═C bond-containing acid anhydride with a second solution containing a diamine compound, causing precipitation of thermosetting amic acid microfine particles from the resulting mixture, and further producing thermosetting imide microfine particles and crosslinked imide microfine particles from the thermosetting amic acid microfine particles.

Abstract: A process for the preparation of an oligomeric polyimide comprises: mixing a tetracarboxylic acid, a dianhydride, a partially hydrolysed dianhydride or a mixture thereof with a diamine in a reaction medium comprising greater than 80% by weight water, and heating mixture in said reaction medium at a temperature above 100° C. for a time sufficient to form said oligomeric polyimide.

Abstract: A method for preparing polyamic acid and polyimide of three-dimensional molecular structure such that these polymers are superior in adhesive strength and high-temperature stability while maintaining their inherent thermal resistance and mechanical properties, and thus can be effectively used as an adhesive material for high temperature adhesive tapes suitable for semiconductor assembly.

Abstract: A polyimide for optical communications, which is expressed by the formula (1) where R1 and R2 are independently selected from the group consisting of CF3, CCl3, unsubstituted aromatic ring group and halogenerated aromatic ring group; R3 and R4 are independently selected from the group consisting of Cl, F, I, Br, CF3, CCl3, unsubstituted aromatic ring group and halogenated aromatic ring group; and n is an integer from 1 to 39. The polyimides have a superior heat resistance, and can avoid the increase in optical absorption loss due to a refractive index increase and deterioration of adhesive and coating properties due to weak surface tension of a polyimide film. In addition, use of the polyimides as a material for a core layer of optical waveguides can expand the selection range of material for the cladding layer of the optical waveguide.

Abstract: The present invention provides a liquid crystal display element having an adequate pre-tilt angle for preventing the reverse domain, as well as excellent electrical properties by preparation of the polyamic acid composition for the liquid crystal display element which comprises a polyamic acid A that excels in electrical properties and a polyamic acid B that has side chains, mixed in the ratio A/B of 50/50 to 95/5 (by weight).

Abstract: A polyimide represented by the following general formula (1); wherein l, m, and n represent not the order of each repeating unit, but the numbers of each repeating unit existing in the molecule, E1 is a photosensitive group, E2 is a group comprising an alkyl group having 2 to 20 carbon atoms, —A(—E1)—, —A(—E2)—, and B each are a divalent organic group, X and Y each are a tetravalent organic group, X, Y, A, B, E1 and E2 may be identical or different among the repeating units, 1 is an integer of 1 or more, m and n each are an integer of 0 or more. The polyimide and polyimide compositions comprising it has thermoreactivity as well as photoreactivity and photosensitivity.

Abstract: A polymide useful as an adhesive for semiconductor assemblies having excellent thermal resistance and adhesive strength at high temperatures.

Abstract: An aqueous binder composition suitable for use as a binder in making wool and board products including fiberglass insulation comprising a phenolic resole resin binder made from phenol and formaldehyde by using an excess amount of a basic catalyst.

Abstract: The present invention provides a novel polyimide composition which includes a cinnamoyl group or a derived cinnamoyl group and has photo-reactivity and heat-reactivity inherent to the cinnamoyl group. Further, a novel diamine and an acid dianhydride according to the present invention are materials mainly used for preparing a novel polyimide composition having the cinnamoyl group or the derived cinnamoyl group in a main chain or a side chain.

Abstract: A polyimide for optical communications, which is expressed by the formula (1), a method of preparing the same, and a method of forming multiple polyimide films using the polyimide, wherein the formula (1) is given by X1, X2, X3, A1, A2, B1, B2, B3, D1, D2, E1, E2, Y1, Y2, Y3, Y4, Y5, Y6, Y7, and Y8, are independently selected from the group consisting of hydrogen atom, halogen atom, alkyl group, halogenated alkyl group, aryl group and halogenated aryl group; Z is a simple chemical bond or selected from the group consisting of —O—, —CO—, —SO3—, —S—, —(T)m—, —(OT)m— and —(OTO)m—, wherein T is alkylene or arylene group substituted by at least one of halogen atom and halogenated alkyl group and m is an integer from 1 to 10; and n is an integer from 1 to 39.

Abstract: Polyimides and the process for preparing polyimides having improved thermal-oxidative stability derived from the polymerization of effective amounts of one or more of the polyamines such as the aromatic diamines, one or more of the tetracarboxylic dianhydrides and a novel dicarboxylic endcap having a formula selected from the group consisting of: wherein R1 is either a radical where R is either hydrogen or an alkyl radical of 1 to 4 carbons, R2 is either OH, NH2, F, or Cl radical, R3 is either H, OH, NH2, F, Cl or an alkylene radical, R4 is either an alkyl, aryl, alkoxy, aryloxy, nitro, F, or Cl radical, and R5 is either H, alkyl, aryl, alkoxy, aryloxy, nitro, F, or Cl radical. The polyimides are useful particularly in the preparation of prepregs and PMR composites.

Abstract: An aqueous binder composition suitable for use as a binder in making wool and board products including fiberglass insulation comprising a phenolic resole resin binder made from phenol and formaldehyde by using an excess amount of a basic catalyst.

Abstract: Polyimide copolymers were obtained containing 1,3-bis(3-aminophenoxy)benzene (APB) and other diamines and dianhydrides and terminating with the appropriate amount of reactive endcapper. The reactive endcappers studied include but should not be limited to 4-phenylethynyl phthalic anhydride (PEPA), 3-aminophenoxy-4′-phenylethynylbenzophenone (3-APEB), maleic anhydride (MA) and nadic anhydride (5-norbornene-2,3-dicarboxylic anhydride, NA). Homopolymers containing only other diamines and dianhydrides which are not processable under conditions described previously can be made processable by incorporating various amounts of APB, depending on the chemical structures of the diamines and dianhydrides used. By simply changing the ratio of APB to the other diamine in the polyimide backbone, a material with a unique combination of solubility, Tg, Tm, melt viscosity, toughness and elevated temperature mechanical properties can be prepared.

Abstract: Terminal-modified imide oligomers with an inherent viscosity of 0.05-1 obtained by reacting 2,3,3′,4′-biphenyltetracarboxylic dianhydride, an aromatic diamine compound and 4-(2-phenylethynyl)phthalic anhydride, and their cured products. There are provided highly practical terminal-modified imide oligomers and their cured products, which cured products have satisfactory heat resistance and mechanical properties.

Abstract: The present invention provides polyimides and co-polyimides that are organosoluble. The polyimides and co-polyimides are prepared from an aromatic diamine having ortho-linked phenylene and pendant tert-butyl group, i.e., 1,2-bis(4-aminophenoxy)-4-tert-butyl-benzene, or its mixture with other diamines, and a mixture of dianhydrides that containing at least one dianhydride selected from s-BPDA, DSDA, ODPA, 6FDA and other diether-dianhydrides.

Abstract: A polyimide film of birefringence less than 0.01 is formed by drawing a copolymerized polyimide comprising a block component and a random component which are molecularly bonded, wherein the block component of copolymerized polyimide comprises an aromatic diamine compound having a rigid structure and an aromatic tetracarboxylic acid compound and wherein the random component of copolymerized polyimide comprises an aromatic diamine compound having a flexible structure and at least two aromatic tetracarboxylic acid components. The resulting polyimide film has high elasticity, a low thermal expansion equivalent to that of metal and low water absorbing properties. A method for its manufacture and a metal laminated plate having improved curl properties in which the polyimide is used as the base material are also disclosed.

Abstract: The present invention relates to a treating agent for liquid crystal alignment, which is an agent for liquid crystal alignment to be used for a method in which polarized ultraviolet rays or electron rays are irradiated on a polymer thin film formed on a substrate in a predetermined direction relative to the substrate plane, and said substrate is used for aligning liquid crystal without rubbing treatment, wherein said agent for liquid crystal alignment contains a polymer compound having photochemically reactive groups in the polymer main chain and a glass transition temperature of at least 200° C.

Abstract: Polyimides and the process for preparing polyimides having improved thermal-oxidative stability derived from the polymerization of effective amounts of one or more of the polyamines such as the aromatic diamines, one or more of the tetracarboxylic dianhydrides and a novel dicarboxylic endcap having a formula selected from the group consisting of: wherein R1 is either a radical where R is either hydrogen or an alkyl radical of 1 to 4 carbons, R2 is either OH, NH2, F, or Cl radical, R3 is either H, OH, NH2, F, Cl or an alkylene radical, R4 is either an alkyl, aryl, alkoxy, aryloxy, nitro, F, or Cl radical, and R5 is either H, alkyl, aryl, alkoxy, aryloxy, nitro, F, or Cl radical. The polyimides are useful particularly in the preparation of prepregs and PMR composites.

Abstract: The present invention provides a process for preparing an optical alignment layer for aligning liquid crystals and liquid crystal displays comprising exposing polyimide layers with polarized light. The invention further describes optical alignment layers, liquid crystal displays incorporating optical alignment layers and novel polymer compositions within the class of polyimide, polyamic acids and esters thereof.

Abstract: An aliphatic polyester amide which is hydrolysis-resistant includes a ternary polycondensation product of monomeric constituents composed of a monomeric constituent A which is at least one diol having a general formula: HO—R1—OH, where R1 is an aliphatic residue having 2-16 carbon atoms; a monomeric constituent B which is at least one dicarboxylic acid having a general formula: HOOC—R2—COOH, where R2 is an aliphatic residue having 1-14 carbon atoms; and a monomeric constituent C which is at least one diamine having a general formula: H2N—R3—NH2, where R3 is an aliphatic residue having 2-16 carbon atoms and is present in an amount of up to about 5% by weight based on total weight of the monomeric constituents, wherein polycondensation proceeds in the presence of a catalyst comprised of constituent D, which is a metal-containing catalyst, in combination with constituent E, which is at least one of an organic phosphorus compound and an inorganic phosphorus compound, and wherei

Abstract: Polyether polymers such as polyetherimides are prepared by a two-step reaction. The first step is the reaction between an alkali metal salt of a dihydroxy-substituted aromatic hydrocarbon, such as bisphenol A disodium salt, and a substituted aromatic compound such as 1,3-bis[N-(4-chlorophthalimido)]benzene, the alkali metal salt being employed in an amount less than stoichiometric. The intermediate low molecular weight polymer thus produced then undergoes reaction with additional alkali metal salt. By this method, a polyether polymer of closely controlled molecular weight can be conveniently prepared.

Abstract: Disclosed is a solvent soluble polyimide and a method for making thereof, which characterizes by producing a solvent soluble polyimide with low electric conductivity through the polymerization of an anhydride and a diamine under the condition with or without catalyst.

Abstract: Addition-cured polyimides that contain the reaction product of an aromatic triamine or trianhydride analogue thereof, a reactive end group such as 5-norbornene-2, 3-dicarboxylic acid, ester derivatives of 5-norbornene-2,3-dicarboxylic acid, anhydride derivatives of 5-norbornene-2,3-dicarboxylic acid, or 4-phenylethynylphthalic anhydride, an aromatic diamine, and a dialkyl ester of an aromatic tetracarboxylic acid. The resultant starlike polyimides exhibit lower melt flow viscosity than its linear counterparts, providing for improved processability of the polyimide. Also disclosed are methods for the synthesis of these polyimides as well as composite structures formed using these polyimides.

Abstract: A method for preparing polyamic acid and polyimide, which is suitable for use in adhesives or adhesive tapes for electronic parts. The polymers have such three-dimensional molecular structures that a significant improvement can be brought about in solvent solubility, thermal resistance, mechanical properties, and adhesive properties onto various substrates. The polyamic acid is prepared by reacting at least one tetracarboxylic dianhydride, at least one aromatic diamine, at least one diamine with a siloxane structure, represented by the following general formula I, and at least one polyamino compound represented by the following general formula II or III. The polyamic acid is converted into polyimide through thermal or chemical imidization.

Abstract: An electrolyte is provided having a backbone that includes a plurality of aromatic constituents coupled together by at least one atom having a &pgr;-cloud, and in which a halogen atom and an ion exchange group are covalently bound directly to the backbone. Furthermore, the electrolyte is high temperature resistant and may comprise perhalogenated polymers, including perhalogenated polyphenylenes, perhalogenated polyamides, perhalogenated aromatic polyesters, perhalogenated polyimide, etc. Still further, the electrolyte may have acidic groups as ion exchange groups, including sulfonic acid groups, or phosphoric acid groups.

Abstract: An aromatic polycarbodiimide comprising a structure represented by the following formula (1) has excellent low moisture resistance, heat resistance and a low dielectric constant: wherein Q is one selected from the group consisting of —CH2—, m is 0 or 1, A is a divalent organic group having 4 or less carbon atoms, Ph is a phenyl group, X's are a hydrogen atom when Q is and the same or different halogen atoms when Q is —CH2—, and n is an integer of 2 to 300.

Abstract: Polymerisable resins which comprise a porphyrinogenic ring system obtained by the reaction of: (a) one or more compounds selected from the group consisting of pyrrole and N-(lower)alkyl pyrroles, any of which may be optionally substituted, and (b) a C4-C6 saturated alicyclic ketone which is capable of reacting with the 2 or 5 position of the pyrrole ring. Resin coating systems comprising the said resins.

Abstract: Bis(halophthalimides) such as, 3-bis[N-(4-chlorophthalimido)]benzene are prepared in slurry in an organic liquid such as o-dichlorobenzene or anisole, by a reaction at a temperature of at least 150° C. between at least one diamino compound, preferably an aromatic diamine such as m- or p-phenylenediamine, and at least one halophthalic anhydride such as 4-chlorophthalic anhydride, in the presence of an imidization catalyst such as sodium phenylphosphinate. The solids content of the reaction mixture is at least about 5% and preferably at least about 12% by weight. The product slurry may be employed directly in the preparation of polyetherimides, and similar slurries may be employed to prepare other polyether polymers.

Abstract: The present invention provides a liquid crystal-aligning agent including, as the resin component, a polyimide precursor containing a chemical structure represented by the following formula (1): The present invention further provides a liquid crystal-aligning agent including, the above polyimide precursor and a polyimide precursor represented by the following general formula (2): (wherein Y is a tetravalent aliphatic group, Z is a bivalent aromatic group, and R is H or an alkyl group).

Abstract: Essentially colorless, transparent polyimide coatings and films prepared by combining aromatic dianhydrides with para-substituted aromatic diamines are provided. The polyimide coatings and films are produced by a process whereby the dianhydride and diamine monomer components are reacted at temperatures of greater than 80° C.

Abstract: High quality films, preimpregnated tape (prepegs) and composites have been fabricated from polyimide precursor “salt-like” solutions. These “salt-like” solutions have a low viscosity (5,000 to 10,000 cp) and a high solids content (50-65% by weight) and can be coated onto reinforcing fiber to produce prepegs with excellent tack and drape at 12-15% residual solvent (˜4-6% water from thermal imidization reaction). The processing of these types of prepegs significantly overcomes solvent removal problems and allows excellent fiber wet out. In addition, the physical characteristics of the polyimide precursor “salt-like” solutions permits processing into high-performance materials through the use of standard prepregging and composite fabrication equipment. The resultant composites are of high quality.

Abstract: The invention relates to a process for preparing hydroxyl- and carboxyl-containing polyesterimide resins, comprising as monomeric components: (A) imide-forming compounds having at least two primary amino groups and/or at least two isocyanate groups or imide-forming compounds having at least one primary amino group and/or at least one isocyanate group and at least one further functional group selected from hydroxyl, carboxyl and/or carboxylic anhydride, (B) polycarboxylic acids and/or their anhydrides and/or their esters and (C) polyols, characterized in that (I) component (A) is reacted with part of component (B) to form a polyimide, (II) the polyimide obtained in accordance with stage (I) is reacted with component (C) to form a polyesterimide, and finally (III) the polyesterimide obtained in accordance with stage (II) is reacted with the remaining part of component (B) to form the Also embraced by the invention is the use of the polyesterimides prepared by the process according to the invention as bi

Abstract: Heat resistant polybenzoxazole resins useful as layer insulation films and protective films for semiconductor, layer insulation films for multilayer circuits, cover coats for flexible copper-clad sheets, solder resist films, liquid crystal-aligned films and the like. These resins have excellent thermal, electrical, physical and mechanical characteristics. Polybenzoxazole precursors are provided, represented by the general formula (A), and are used to obtain polybenzoxazole resins, represented by the general formula (D). In the formulas (A) and (D), n denotes an integer from 2-1000, and X denotes a structure having a formula selected from structures indicated at (B). In the formulas at (B), Y denotes a structure having a formula selected from those indicated at (C), and the hydrogen atom(s) on the benzene ring in these structures are optionally substituted.

Abstract: The present invention relates to the synthesis of new type of diamine monomer, 1,3-bis(4-amonophenoxy)naphthalene, and with such a compound to produce a series of aromatic polymers, including polyamide, polyimide, copoly(amide-imide)s, etc., such polymers having excellent resistance to heat and mechanical properties.

Abstract: A process for producing polyimide microfine particles which is amenable to free control of particle morphology and particle diameter distribution is provided. A polyamic acid and a polyimide, each in the form of microfine particles with good monodispersibility, are also provided. There is also provided a process for producing polyimide microfine particles from a tetracarboxylic anhydride and a diamine compound which comprises (a) a first step of preparing a first solution containing the tetracarboxylic anhydride and a second solution containing the diamine compound, (b) a second step of mixing the first and second solutions and causing a polyamic acid to precipitate in the form of microfine particles from the mixed solution under ultrasonic agitation, and (c) a third step of imidating the polyamic acid particles to provide the objective polyimide in the form of microfine particles.

Abstract: The present invention is directed to polyimide systems which simultaneously offer low toxicity, a high glass transition temperature, excellent thermal oxidative stability, and desirable processing characteristics. These various polyimide systems include mixtures of monomeric reactants, polyimide-precursor reaction products, polyimides, and polyimide-containing articles. In one aspect of the invention, the mixture of monomeric reactants includes at least one dia-nhydride or a derivative thereof, and at least one diamine. The diamine may be 4,4′-[1,4-phenylene-bis(1-methylethylidene)]bisaniline, 4,4′-[1,3-phenylene-bis(1-methylethylidene)]bisaniline, and/or a derivative thereof. The diamine also may include a phenylenediamine, 2,2-bis[4-(4-aminophenoxyl)phenyl]propane, 4,4′(1,4-phenylene-bismethylene)bisaniline, and/or a derivative thereof. In addition, the mixture may include a reactive end-capping agent and/or a non-reactive end-capping agent.

Abstract: A polyimide precursor solid residuum is an admixture of an aromatic dianhydride or derivative thereof and an aromatic diamine or dervative thereof plus a complexing agent, which is complexed with the admixture by hydrogen bonding. The polyimide precursor solid residuum is effectively employed in the preparation of polyimide foam and the fabrication of polyimide foam structures.

Abstract: Polyimide copolymers were obtained containing 1,3-bis(3-aminophenoxy)benzene (APB) and other diamines and dianhydrides and terminating with the appropriate amount of a non-reactive endcapper, such as phthalic anhydride. Homopolymers containing only other diamines and dianhydrides which are not processable under conditions described previously can be made processable by incorporating various amounts of APB, depending on the chemical structures of the diamines and dianhydrides used. Polyimides that are more rigid in nature require more APB to impart processability than polyimides that are less rigid in nature. The copolymers that result from using APB to enhance processability have a unique combination of properties including: excellent thin film properties, low pressure processing (200 psi and below), improved toughness, improved solvent resistance, improved adhesive properties, improved composite mechanical properties, long term melt stability (several hours at 390 C.), and lower melt viscosities.

Abstract: The invention relates to a photosensitive polyimide resin composition comprising (A) a polyamic acid having, in its main chain, repeating units formed from a polycondensation product of at least one tetracarboxylic acid or tetracarboxylic anhydride thereof with at least one diamine compound, and having actinic ray-sensitive functional groups at both terminals thereof; (B) a photosensitive auxiliary having a photopolymerizable functional group; (C) a photopolymerization initiator; and (D) a solvent, wherein 1 the polyamic acid is such that when the repeating unit represented by the formula (1) is defined as a unit molecular weight, a unit molecular weight per carboxyl group (unit molecular weight/COOH) falls within a range of from 200 to 300, and 2 the photosensitive resin composition permits the formation of a polyimide film having a residual stress of 40 MPa or lower and a coefficient of thermal expansion of 30 ppm/.degree. C.

Abstract: A diamine which is useful in preparing a new flexible polyamide and polyimide with an aromatic dicarboxylic acid and a tetracarboxylic dianhydrides, respectively, has a general formula as follows: ##STR1## wherein R.sub.1 is methyl (--CH.sub.3) and n is an integer ranging from 1 to 4.

Abstract: A compound of the formula: ##STR1## wherein Ar.sup.

Abstract: Polyimide copolymers were obtained containing 1,3-bis(3-aminophenoxy)benzene (APB) and other diamines and dianhydrides and terminating with the appropriate amount of reactive endcapper. The reactive endcappers studied include but should not be limited to 4-phenylethynyl phthalic anhydride (PEPA), 3-aminophenoxy-4'-phenylethynylbenzophenone (3-APEB), maleic anhydride (MA) and nadic anhydride (5-norbornene-2,3-dicarboxylic anhydride, NA). Homopolymers containing only other diamines and dianhydrides which are not processable under conditions described previously can be made processable by incorporating various amounts of APB, depending on the chemical structures of the diamines and dianhydrides used. By simply changing the ratio of APB to the other diamine in the polyimide backbone, a material with a unique combination of solubility, Tg, Tm, melt viscosity, toughness and elevated temperature mechanical properties can be prepared.

Abstract: Water soluble polyalkanolamides and a process to prepare same by reacting polycarboxylic acid or its anhydride, ester or halide derivative with at least one alkanolamine and optionally with a polyamine and removing the condensation byproduct water, alcohol or hydrogen halide.

Abstract: A polyimide precursor solution having a high concentration yet low viscosity, a polyimide coating film having satisfactory physical properties which is prepared from the polyimide precursor solution, and a process for producing a polyimide coating film using the polyimide precursor solution. The polyimide precursor solution has dissolved therein a specific salt of a diamine and a tetracarboxylic acid and/or a dicarboxylic acid-dialkyl ester in a high concentration, the diamine and the tetracarboxylic acid and/or the dicarboxylic acid-dialkyl ester being capable of forming a polyimide. Also disclosed is a polyimide coating film obtained by heating the solution to cause imidization and a process for producing the polyimide coating film.

Abstract: A polyimide resin having good thermal stability and good adhesion to a metal foil is disclosed. The polyimide resin is prepared by dissolving at least one diamine in a polar aprotic solvent followed by the addition of an aromatic tetracarboxylic acid dianhydride to the solution of the aromatic diamines to prepare a polyamic acid solution, imidizing this solution to a polyimide resin by heating at a temperature above 250.degree. C., the polar aprotic solvent comprising at least 1 weight % of acetone. Polyimide laminates with a metal foil, such as a copper foil, are also described. The laminates may be used to form flexible printed circuit boards.