Abstract: Polyimides and polyamide-acids having improved solubility and processing characterisitcs are provided having incorporated into the polymeric chain as a novel aromatic diamine compound, 2-(3-aminophenyl)-2-(4-aminophenyl) hexafluoropropane (3,4'-6F Diamine). The polyamide-acids and polyimides are prepared by reacting the 3,4'-6F Diamine with aromatic tetracarboxylic acids or anhydrides thereof. It has been found that the polyimides of this invention have improved solubility characterisitics, low dielectric constants and improved thermal flow properties as a consequence of the meta/para positioning of the amino groups on the diamine, which renders these polymers more readily melt spinnable for the production of fibers. The polymers may also be compression molded and fabricated into composites at moderate temperatures and pressures. Solutions of the polyimides may be cast into films.

Abstract: The present invention provides polyamide-polyamide-polyimide and polybenzoxazole-polyamide-polyimide polymers derived therefrom with improved processing and film characteristics having incorporated into the polymeric backbone the polymeric condensation residuum of novel aromatic diamino compounds having the formula: ##STR1## wherein A is selected from the group consisting of SO.sub.2, O, S, CO, C.sub.1 to C.sub.6 alkylene, perfluoroalkylene or perfluoroarylalkylene having from 1 to 10 carbon atoms and a bond directly linking the two aromatic groups, and R is selected from the group consisting of hydrogen, hydroxy and C.sub.1 to C.sub.4 alkoxy.The PA-PA-PI polymers of this invention are prepared by reacting compounds of the above formula alone or admixed with other aromatic diamines, with carboxyphenyl trimellitimide or the acid halide or ester derivatives thereof, alone or admixed with one or more aromatic diacid chlorides and/or one or more aromatic tetracarboxylic acids or anhydrides thereof.

Abstract: High molecular weight polyimides are formed by polycondensation of 2,2-bis(4-aminophenyl) hexafluoropropane or 2,2-bis(3-aminophenyl) hexafluoropropane with one or more of bis-(3,4 dicarboxyphenyl) ether dianhydride; 3,3', 4,4' benzophenone tetracarboxylic acid dianhydride; 3,3', 4,4' diphenyl tetracarboxylic acid dianhydride and 2,2-bis(3,4 dicarboxyphenyl) hexafluoropropane dianhydride. Generally, the polymers of the present invention are characterized by a molecular weight of more than about 90,000.

Abstract: Novel aromatic polyamides high in heat resistance and soluble in various organic solvents are obtained each by reacting 2,2'-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropane or a simple derivative thereof with an aromatic dicarboxylic acid, e.g. isophthalic acid, or its dihalide or diester.

Abstract: Novel polyarylate polymers comprise alternating moieties derived from an aromatic dicarboxylic acid halide, with moieties derived from a hydroxyaryl-substituted 1,6-diaza [4.4] spirodilactam compound and, optionally, with moieties derived from a di(hydroxyphenyl) compound. The polyarylate polymers are thermoplastic polymers characterized by relatively high glass transition temperatures.

Abstract: The present invention provides novel heat stable polyimide and polyamic acid precursor polymers having excellent flow properties which render them more readily processible into fibers, films, sheets and other molded articles. The polymers are prepared by forming the polycondensation product of one or more aromatic diamines and one or more aromatic dianhydride monomers, at least one of said diamine monomers having the structure: ##STR1## wherein R is CF.sub.3 or phenyl. The polyimides of this invention exhibit improved solubility and low temperature flow characteristics, low moisture uptake, high thermal stability, low dielectric constant and good hydrolytic stability.

Abstract: Polyamide-imides derived from trimellitic acid compounds and an aromatic diamine are improved in moisture resistance when from 10 to about 90 mole % of the trimellitic acid compound is replaced by a biphenyl tetracarboxylic acid compound.

Abstract: Novel polyamide polymers incorporating moieties of a [4.4] spirodilactam with spiro ring nitrogens in the 1- and 6- spiro ring positions and moieties of a primary diamine are produced by reaction of the primary diamine and a spirodilactam precursor selected from 4-oxoheptanedioic acid compounds or [4.4] spirodilactones having spiro ring oxygen atoms in the 1- and 6- spiro ring positions.

Abstract: Production of polyenaminonitriles including those which can be cyclized to very stable poly(aminoquinolines) without the evolution of any small molecules and thus in a manner free of volatiles. The polyenaminonitriles are polymers which have desirable dielectric properties, and include those which can be cyclized to poly(aminoquinolines) without the evolution of volatiles to make defect-free films and composites of similar dielectric properties because of this characteristic.

Abstract: A terminal-modified imide oligomer having an unsaturated group as a terminal group and an imide bond inside of the oligomer which is produced by reacting 2,3,3',4'-or 3,3',4,4'-biphenyltetracarboxylic acid or its derivative, a diamine compound, and an unsaturated dicarboxylic acid or its derivative and/or an unsaturated monoamine in an organic solvent is disclosed. This oligomer has a logarithmic viscosity of not more than 1.0. This logarithmic viscosity is measured under the conditions of concentration of 0.5 g/100 ml-solvent (N-methyl-2-pyrrolidone) and a temperature of 30.degree. C., and has a melting point of 50.degree. to 300.degree. C.

Abstract: The present invention provides novel heat stable polyamide-imide polymers having excellent flow properties and moisture stability which render them more readily processible into fibers, films, sheets and other molded articles. The polymers are prepared by forming the polycondensation product of one or more aromatic diamines, one or more tetrafunctional aromatic dianhydrides, and a difunctional aromatic carboxylic acid or amide-forming derivative thereof containing the groups ##STR1## linking two aromatic moieties, wherein R is CF.sub.3 or phenyl. In addition to improved flow properties, the polyamide-imide polymers of this invention also exhibit improved solubility properties in most organic solvents, improved resistance to attack by chlorinated solvents such as trichloroethylene as compared with polyimides, improved hydrophobic properties as well as excellent thermal properties, including resistance to thermooxidative degradation.

Abstract: The present invention provides novel heat stable polyamide polymer having excellent flow properties which render them more readily processible into fibers, films, sheets and other molded articles. The polymers are prepared by forming the polycondensation product of one or more aromatic diamines and one or more aromatic dibasic acid monomers or amide-forming derivatives thereof, at least one of said diamine monomers having the structure: ##STR1## where R is CF.sub.3 or phenyl. The polyamides of this invention exhibit improved solubility and low temperature flow characteristics, low moisture uptake, high thermal stability, low dielectric constant and good hydrolytic stability.

Abstract: Thermosetting resin compositions are provided which comprise aromatic bismaleimide derivatives, for example, 2,2-bis[4(3-maleimidephenoxy)phenyl]propane and diamine derivatives, for example, 4,4'-bis(3-aminophenoxy)biphenyl. Prepolymers are also prepared by conducting heat-treatment of said compositions. The compositions of this invention are used for thermoforming such as compression molding etc. as well as raw materials of adhesives and coatings. The compositions provide molded articles which are excellent, for example, impact strength, flexibility and high-temperature stability.

Abstract: A process for producing a silicon-containing polyamic acid affording a silicon-containing polyimide having a low thermal expansion coefficient and a process for producing the silicon-containing polyimide are provided, the former process comprising reacting pyromellitic acid dianhydride (A.sup.1 mols) and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (A.sup.2 mols) with a diamine of the following formula (I) (B mols) and an aminosilicon compound of the formula (II) so as to satisfy the following expressions (III) and (IV): ##STR1## wherein R.sup.1 is methyl, ethyl, methoxy, ethoxy or halogen; R.sup.2 is alkyl or alkyl-substituted phenyl; X is a hydrolyzable alkoxy, acetoxy or halogen; m is 0, 1 or 2; n is 1 or 2; and k is 1, 2 or 3; andthe latter process comprising baking a solution of the above silicon-containing polyamic acid at 50.degree. to 500.degree. C.

Abstract: In humid atmospheres (e.g., 40% relative humidity or above) solutions of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride/2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane polyimides tend to be unstable in the sense that during spin coating operations undesirable precipitate formation occurs on the rotating surface of the water. The result is the formation of unacceptable coatings due to their irregularity and lack of uniformity. Described are compositions especially adapted for use in spin coating wafers of semiconductive materials, which comprise solutions of these polyimide polymers in a solvent containing at least 10% of a cycloaliphatic ketone (e.g., cyclohexanone) or mixture of cycloaliphatic ketones, such that the solution (a) contains on a weight basis from about 5% to about 50% of the polyimide, and (b) does not undergo precipitate formation during spin coating in an atmosphere of up to at least about 55% relative humidity.

Abstract: A copolymerized polyamic acid salt having a recurring unit represented by following formula (I) and (II) and the process for preparing thereof. ##STR1## wherein (A) or (A') represents a formula ##STR2## wherein, R.sup.1 represents a tetravalent group having at least 2 carbon atoms; R.sup.2 represents a divalent group having at least 2 carbon atoms; and R.sup.31, R.sub.32, R.sup.33, R.sup.41, R.sup.42, R.sup.43, R.sup.5, and R.sup.6 each represents a monovalent group having 1 to 30 carbon atoms selected from an aliphatic group, an alicyclic group, an aromatic group, a group in which an aliphatic group is combined with an alicyclic group or an aromatic group, each of these groups substituted by a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group, or an acetoxy group, or a hydrogen atom; at least one of said R.sup.31, R.sup.32, R.sup.33, R.sup.41, R.sup.42, R.sup.43, R.sup.5 and R.sup.

Abstract: A solvent-soluble polyimide obtained from an exo-form dicarboxylic acid anhydride with an aromatic diamine, e.g. 2,2,-bis[4-(4-aminophenoxy)phenyl]propane is improved in film-forming properties and transparency, and particularly suitable for producing an orientation controlling film in a liquid crystal display device.

Abstract: Coolyimides and copolyamide-acids having improved solubility and processing characteristics are provided having incorporated into the polymeric chain as a novel aromatic diamine compound, 2-(3-aminophenyl)-2-(4-aminophenyl) hexafluoropropane (3,4'-6F Diamine). The copolyamide-acids and copolyimides are prepared by reacting the 3,4'-6F Diamine with a mixture of two or more aromatic tetracarboxylic acids or anhydrides thereof. It has been found that the copolyimides of this invention have improved solubility characteristics, low dielectric constants and improved thermal flow properties as a consequence of the meta/para positioning of the amino groups on the diamine, which renders these copolymers more readily melt sqinnable for the production of fibers. The copolymers may also be compression molded and fabricated into composites at moderate temperatures and pressures. Solutions of the copolyimides may be cast into films.

Abstract: Described are flexible polyimide foams having enhanced compression characteristics and softness for use in the manufacture of seat cushions and methods for the production of such foams and precursors therefor. These foams are produced from novel polyimides prepared by reaction of at least one aromatic or heterocyclic primary diamine with a mixture of at least two organic tetracarboxylic acids or derivatives thereof, at least one of which is from 1 to 40 mol percent of a 2-(vicinal-dicarboxycyclohexenyl)succinic acid or derivative thereof and a second of which is an aromatic tetracarboxylic acid or derivative thereof.

Abstract: In humid atmospheres (e.g., 55% relative humidity or above) solutions of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride/2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane polyamic acid polymers tend to be unstable in the sense that during spin coating operations undesirable precipitate formation may occur on the rotating surface of a semiconductor wafer. The result is the formation of unacceptable coatings due to their irregularity and lack of uniformity. Described are solutions of these polyamic acid polymers in a solvent containing at least 40% by weight of one or more liquid aromatic hydrocarbons having a boiling point of at least about 110.degree. C. and at least 5% by weight of one or more dipolar aprotic solvents having a boiling point of at least about 150.degree. C.

Abstract: A novel fluorine-containing aromatic compound of the formula: ##STR1## wherein X is ##STR2## in which R.sub.f is a perfluoroalkyl group having 1 to 10 carbon atoms, R.sub.f ' is a perfluoroalkyl group having 1 to 12 carbon atoms, p is an integer of 1 to 3, q is an integer of 0 to 3, r is 0 or 1, s is an integer of 0 to 5 and t is an integer of 0 to 5,Y is X, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a fluoroalkyl group having 1 to 8 carbon atoms, andeach A is independently ##STR3## in which D is an amino, carboxyl, hydroxyl, methyl or haloformyl group, and n is an integer of 1 or 2, or ##STR4## can be used to derive various compounds, some of which are useful for preparing a fluorine-containing epoxy compound or polyimide with good properties.

Abstract: A copolyimide foam comprising the reaction product of one or more of an aromatic tetracarboxylic acid and a compound of the formula: ##STR1## where x is an integer from 1 to 12 and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same or different and are hydrogen or C.sub.1 to C.sub.6 linear or branched alkyl a mixture thereof with two or more diamines at least one of which being a heterocyclic diamine having a nitrogen atom in the ring and the other being a para- or meta-substituted aromatic diamine free of aliphatic substitution.Processes for producing the above copolyimide foam are also disclosed.

Abstract: Described is a process for producing, in particulate form, aromatic polyimides based on one or more 2,2-bis[4-(aminophenoxy)-phenyl]hexafluoropropanes. The process involves forming, heating and agitating in a medium composed of dipolar aprotic solvent and liquid aromatic hydrocarbon solvent, a homogeneous solution of a polyamic acid derived from a substantially equimolar mixture of (i) an aromatic tetracarboxylic dianhydride and (ii) a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane, such that a separate phase of particulate aromatic polyimide is formed in such medium. The process avoids difficulties caused by the tendency of the wet polyimide polymer to agglomerate into stringy or tacky masses which can foul reactor and agitator surfaces.

Abstract: A film comprised of at least one monomolecular layer composed essentially of a polyimide having repeating units of the formula: ##STR1## wherein R.sup.1 is a tetravalent organic group and R.sup.2 is a bivalent organic group.

Abstract: Amorphous and transparent copolyamides having glass transition temperatures, Tg, greater than 140.degree. C. and improved thermomechanical properties, well adopted for the production of a wide variety of useful shaped articles, contain specified amounts of terephthalic acid, 2-methylpentamethylenediamine and hindered aromatic diamine recurring structural units.

Abstract: Crystallized semiaromatic copolyamides having glass transition temperatures, Tg, greater than 142.degree. C., melting points, Tm, less than 290.degree. C. and improved thermomechanical properties, well adopted for the production of a wide variety of useful shaped articles, contain specified amounts of terephthalic acid, 2-methylpentamethylenediamine and hindered aromatic diamine recurring structural units.

Abstract: Highly-soluble, fully-cyclized siloxane polyimides, which contain at least in part, polymerized units derived from 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl) ethylidene]-bis(1,2-benzenedicarboxylic acid anhydride), (6FDA), are disclosed. The polymeric compositions, their preparation and film/coating products are described.

Abstract: This invention relates to new fluorine-containing polyimides, polyamide-acids/esters, polyamides, addition polyimides and imide oligomers which exhibit low melting points, better solubilities, low dielectric constants, superior thermal and thermal oxidative stability, and improved processing characteristics.The products of this invention are characterized by the fact that they are derived from 4,4'-bis[2-(3,4-(dicarboxyphenyl)hexafluoroisopropyl]diphenyl ether dianhydride.

Abstract: Disclosed are polyoxyalkylene polyimide polyester polymers that have utility as thermoplastic molding compositions, diacid monomers useful for making said polyester polymers and poly(oxy alkylene) polyimides. The latter two compounds have utility as hot melt adhesives.

Abstract: Novel polymers containing amide and imide moieties are produced by reaction of a spirodilactam precursor selected from 4-oxoheptanedioic acid compounds or 1,6-dioxa [4,4] spirodilactones, a primary diamine and an aromatic tricarboxylic acid compound. The polymer products have relatively high glass transition temperatures.

Abstract: The present invention relates to copolyimides of 100-70 mol % of recurring structural units of the formula I and 0-30 mol % of recurring structural units of the formula II ##STR1## in which Z.sup.a is a tetravalent aromatic tetracarboxylic acid radical other than that of thioxanthonetetracarboxylic acid, the carboxyl groups thereof in each case being located in pairs in the ortho-position or peri-position relative to one another, and X.sup.a is a divalent aromatic diamine radical which, in at least one ortho-position relative to at least one nitrogen atom, carries a hydrocarbon substituent having at least one aliphatic .alpha.-hydrogen atom or X.sup.a is a radical of the formula III ##STR2## in which X.sup.c is a divalent aromatic diamine radical which, in ortho-position relative to both nitrogen atoms, carries in each case at least one monovalent hydrocarbon substituent having at least one aliphatic .alpha.-hydrogen atom, n assumes an average value of 1.0 to 2.5, Z.sup.b is as defined for Z.sup.a and X.sup.

Abstract: Described is a process for producing, in particulate form, aromatic polyimides based on one or more 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropanes. The process involves forming a solution of an equimolar mixture of (1) an aromatic tetracarboxylic dianhydride and (2) a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane as the sole or predominant aromatic diamine in (3) a solvent composed of (i) tetrahydrofuran, or (ii) one or more alkyltetrahydrofurans having a normal boiling point below 100.degree. C., or (iii) a mixture of (i) and (ii), and heating and agitating such solution in a closed reaction system under super-atmospheric pressure such that a separate phase of particulate aromatic polyimide is formed. The process avoids difficulties caused by the tendency of the wet polyimide polymer to agglomerate into stringy or tacky masses which can foul reactor and agitator surfaces.

Abstract: The present invention provides novel heat stable polyamide-imide polymers having excellent flow properties which render them more readily processible into fibers, films, sheets and other molded articles. The polymers are prepared by forming the polycondensation product of one of more aromatic diamines, one or more trifunctional acid anhydride monomers, and one or more tetrafunctional aromatic dianhydrides, at least one of said monomers containing the groups ##STR1## linking two aromatic moieties, wherein R is CF.sub.3 or phenyl. In addition to improved flow properties, the polyamide-imide polymers of this invention also exhibit improved solubility properties in most organic solvents, improved resistance to attack by chlorinated solvents such as trichloroethylene as compared with polyimides, improved hydrophobic properties as well as excellent thermal properties including resistance to thermooxidative degradation.

Abstract: Polyimides which essentially consist of 0.1 to 100 mol % of at least one structural element of the formula I ##STR1## and 99.9 to 0 mol % of at least one structural element of the formula II and/or III ##STR2## in which Z and Z' are a tetravalent aromatic radical, Q' is a trivalent aromatic radical, X and X' are a divalent radical of an organic amine, are autophotocrosslinkable. They are suitable for the production of protective films and photographic relief images.

Abstract: Coated article has a thermoplastic substrate and a surface coating of a transparent ultraviolet light-resistant polymer which is the reaction product of a melamine compound, a polyol, and a multimeric benzotriazole compound. The coating of the coated article retains its UV absorbance during curing and exposure to elevated temperatures.

Abstract: Novel thermoplastic polymers of relatively high glass transition temperatures are characterized by five-carbon moieties having a keto group in the 3-position alternating with bis(benzoheterocyclic) moieties. The polymers are produced by reaction of a keto-C.sub.5 source, selected from 4-oxoheptanedioic acid compounds or a 1,6-dioxa [4.4] spirodilactone, with a bis(ortho-phenylene amine) compound. Further cyclization of the initial polymer product or reaction of a bis(ortho-phenylenediamine) provides a polymer having a hexacyclic repeating unit.

Abstract: A polyquinoxaline polymer is prepared by self condensation of a monomer having both a 1,2-diketone and a 1,2-primary diamine in the molecule. The resultant polymers can be used as dielectric films, adhesions, varnishes and membranes.

Abstract: Highly soluble, optically transparent to clear aromatic polyimides in the visible range are disclosed. The dianhydrides from which the polyimides are prepared are 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl) ethylidene] bis(1,2-benzenedicarboxylic anhydride) which can be partially replaced with either pyromellitic dianhydride or 3,3',4,4'-benzophenone tetracarboxylic dianhydride. The diamines from which the polyimides are prepared are m- or p- phenylene diamines which are substituted ortho to the amino groups with primary or secondary alkyl groups having 1 to 6 carbon atoms preferably methyl or ethyl.

Abstract: An amphiphilic high polymer comprises a linear recurring unit containing at least divalent organic group (R.sub.1) having at least two carbon atoms, at least divalent organic group (R.sub.2) having at least two carbon atoms, and at least one C.sub.10-30 hydrocarbon-containing group (R.sub.3) which may have one or more substituent groups, said organic groups R.sub.1 and R.sub.2 being connected to each other by a divalent connecting group, and said hydrocarbon-containing group R.sub.3 being boned to said recurring unit by a covalent bond, and the method for producing the same comprises polycondensating a combination of monomers containing R.sub.1 and R.sub.2.

Abstract: Extraction of polyamic acid-polyimide gel in bipolymerized polyimide manufacturing process with a solvent containing an extraction-enhancing agent, which is a pyridine, picoline, or quinoline, leads to a polyimide film having increased molecular weight. Polyimides are valuable materials used in fabricating articles which must withstand high temperatures, especially in aerospace applications, and in the manufacture of electronic circuit boards.

Abstract: A polyamideimide having an inherent viscosity of above 0.48 which comprises a unit of the following formula (II) ##STR1## and a unit of the following formula (IV) ##STR2## as main units forming the molecular chains of the polyamideimide, and an intimate mixture of the polyamideimide and a plasticizing material for the polyamideimide.

Abstract: An amphiphilic polyimide precursor having at least 70% by mole of the recurring unit of the formula (1): ##STR1## wherein R.sup.1 is a tetravalent group having at least 2 carbon atoms, R.sup.2 is a bivalent group having at least 2 carbon atoms, and R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are hydrogen atom or a monovalent group having 1 to 30 carbon atoms selected from an aliphatic group, an alicyclic group, an aromatic group, a group in which an aliphatic group is combined with an alicyclic group or an aromatic group, and their groups substituted by a halogen atom, nitro group, amino group, cyano group, methoxy group or acetoxyl group, provided that at least one, preferably at least two, of R.sup.3, R.sup.4, R.sup.5 and R.sup.

Abstract: Acetylene terminated aspartimides are prepared using two methods. In the first, an amino-substituted aromatic acetylene is reacted with an aromatic bismaleimide in a solvent of glacial acetic acid and/or m-c=resol. In the second method, an aromatic diamine is reacted with an ethynyl containing maleimide, such as N-(3-ethynylphenyl) maleimide, in a solvent of glacial acetic acid and/or m-cresol. In addition, acetylene terminated aspartimides are blended with various acetylene terminated oligomers and polymers to yield composite materials exhibiting improved mechanical properties.

Abstract: A premix, an origomeric prepolymer obtainable from a limited addition polymerization effected with the premix and a thermosetting resin obtainable from such premix or prepolymer as well as fiber reinforced plastics made of such thermosetting resin which are excellent in the heat resistance, impact resistance and flexibility and exhibit a high toughness, wherein said premix comprises, as a first essential component, an amine-terminated amic acid expressed by the formula, ##STR1## in which R.sup.1 stands for a tetravalent aromatic residue having 6 to 20 carbon atoms and R.sup.2 denotes a divalent organic residue having 2 to 20 carbon atoms, said amic acid being produced by reacting a tetracarboxylic dianhydride with a diamine compound, and, as a second essential component, an N,N'-bis maleimide of the formula, ##STR2## wherein R.sup.3 denotes a divalent organic residue having 2 to 20 carbon atoms, the mole ratio of [N,N'-bismaleimide]/[amine-terminated amic acid] being in the range from 1 to 3.

Abstract: A novel class of polymers and processes used in their preparation are described. The polymers are produced by a reaction between polyfunctional amines and quinones. Some are infusible and intractable. Others are eminently suitable for the production of coatings, adhesives, insulators, etc. Some polymers, in solution in appropriate solvents adhere to metals, siliceous materials, composites with sufficient affinity to displace water. The polymers can be cured by heat or chemicals to an impervious and insoluble material that is not wetted by water.

Abstract: Disclosed herein are free-standing, pinhole-free, ultrathin polyimide films having thicknesses of about 400 angstroms or less and a process to prepare them. The films find particular utility in separatory applications.

Abstract: A polyamide acid solution is disclosed, comprising a polyamide acid comprising as main components at least one recurring unit selected from the recurring units of the formulae (I) to (IV) and a recurring unit of formula (V), dissolved in an organic solvent comprising as a main component an amide type polar solvent having a boiling point of 170.degree. C. or less. The solution is capable of forming a polyimide film which has colorless transparency free from coloration and strong adhesion to a substrate for liquid crystal cell enough to prevent penetration of water into interface between the substrate and film. The solution is particularly useful for forming a liquid crystal oriented film.

Abstract: A colorless transparent polyimide shaped article having as a main component at least one recurring unit selected from the recurring units of the formulae (I) to (IX). It is useful, for example, as an oriented film in liquid crystal display devices. The polyimide shaped article is produced by a process which comprises preparing a solution of a polyamide acid having as a main component at least one recurring unit selected from the recurring units of the formulae (V) to (VIII) in an amide-type organic polar solvent, forming a shaped article of the polyamide acid from the solution, and imidizing the resulting shaped article of the polyamide acid.

Abstract: A colorless transparent polyimide shaped article having as a main component at least one recurring unit selected from the recurring units of the formulae (I) to (III), which is useful, for example, as an oriented film in liquid crystal display devices. The polyimide shaped article is produced by a process which comprises preparing a solution of (A) a polyimide precursor obtained by reacting a diamino compound comprising as a main component at least one aromatic diamine having amino groups at the m-position selected from diamines of formulae (IV) to (VI) with a tetracarboxylic acid compound comprising as a main component a tetracarboxylic acid dianhydride of formula (VII) dissolved in (B) at least one organic polar solvent selected from N,N-dimethylacetamide, N,N-dimethylformamide, bis(2-methoxyethyl)ether, cresol and halogenated phenols; forming a shaped article of the polyimide precursor from the solution; and imidizing the resulting shaped article.

Abstract: Polyimides are prepared from acetylene substituted polyimide oligomers via an addition polymerization reaction which involves homopolymerization. These polymers exhibit low void content when cured and possess superior thermal stability characteristics and physical properties such as structural strength. One of their unique properties is their ability to be processed into useful articles at moderate pressures and temperatures.