Abstract: This invention relates the novel diamines, the polyimide oligomers and the polyimides derived therefrom and to the method of preparing the diamines, oligomers and the polyimides. The thermoplastic polyimides derived from the aromatic diamines of this invention are characterized as having a high glass transition temperature, good mechanical properties and improved processability in the manufacture of adhesives, electronic and composite materials for use in the automotive and aerospace industry. The distinction of the novel aromatic diamines of this invention is the 2,2',6,6'-substituted biphenyl radicals which exhibit noncoplanar conformation that enhances the solubility of the diamine as well as the processability of the polyimides, while retaining a realatively high glass transition temperature and improved mechanical properties at useful temperature ranges.

Abstract: Regiospecific polyamide-imides are cast to form membranes which exhibit superior gas separation properties when compared to polyamide-imide membranes formed from random copolymers. The regiospecific polyamide-imides are synthesized by reacting specific aromatic diimide dicarboxylic acids with select aromatic diamines.

Abstract: The present invention relates to amine compositions and the preparation of polyimides. The polyimides can be used for inducing alignment of a liquid crystal medium with polarized light and liquid crystal display elements.

Abstract: An optical alignment polymer having an optical aligning functional group simultaneously introduced into its main chain and side chain, an alignment layer formed using the optical alignment polymer and a liquid crystal display device having the alignment layer are provided. The optical alignment polymer has excellent alignment performance and stability against heat or impact.

Abstract: Phthalonitrile thermoset polymers and composites having flame resistance formed by combining a phthalonitrile monomer in the melt stage with a halogen-containing aromatic amine curing agent. The halogen-containing aromatic amine curing agent is selected from the group consisting of aromatic amine curing agents having the general formula:NH.sub.2 --(Ar.sup.2 O--).sub.y Ar.sup.1 --X--Ar.sup.1 (--OAr.sup.2).sub.y --NH.sub.2wherein Ar.sup.1 and Ar.sup.2 are substituted or unsubstituted aromatic groups, y is 0 or greater, and X is --C(CF.sub.3).sub.2 -- and aromatic amine curing agents having the general formula:NH.sub.2 --(Ar.sup.4 O--).sub.u Ar.sup.3 --Z--Ar.sup.3 (--OAr.sup.4).sub.u --NH.sub.2wherein Z is a connecting bond or a linking group other than oxygen or --C(CF.sub.3).sub.2 --, u is 0 or greater, and Ar.sup.3 and Ar.sup.4 are aromatic groups and wherein either Ar.sup.3 or Ar.sup.1 or both Ar.sup.3 and Ar.sup.4 are substituted with at least one halogen atom or halo-substituted alkyl group.

Abstract: A fiber-reinforced phthalonitrile composite is made by impregnating or coating a fibrous material with a phthalonitrile prepolymer mixture containing a phthalonitrile monomer and an aromatic amine curing agent that is thermally stable and nonvolatile at a temperature up to about 375.degree. C., and that contains at least one electron withdrawing substituent effective to reduce the reactivity of the aromatic amine curing agent with the phthalonitrile monomer.

Abstract: Polyetherimides are prepared by conventional means from hindered diamines such as the isomeric methyl-4,6-diethyl-1,3-phenylenediamines and bis(2-chloro-4-amino-3,5-diethylphenyl)methane. They have unusually high glass transition temperatures.

Abstract: A process for the preparation of polyester-imide resin of the formula ##STR1## wherein n represents the number of segments present and is a number of from about 10 to about 10,000; R' is alkyl or alkylene; and R is independently an oxyalkylene or a polyoxyalkylene by the reaction of trimellitic acid, or a trimellitic anhydride, a glycol and a diamine of the formula ##STR2## wherein R represents a hydrogen or alkyl group; and n represents the number of monomer segments, and is a number of from about 1 to about 10, and which reaction is accomplished by heating the aforementioned components.

Abstract: A photosensitive resin composition comprising;(A) a polyimide precursor containing an acrylic or methacrylic group;(B) a tertiary amine compound represented by the general formula: ##STR1## wherein R.sup.6 is a monovalent organic group having 3 or less carbon atoms, R.sup.7 is a divalent organic group having 3 or less carbon atoms, and R.sup.8 is a hydrogen atom or a methyl group; and(C) at least one of a photopolymerization initiator and a sensitizer.This composition has a sufficient sensitivity even when thick films are formed, has a superior developability in an aqueous alkali solution, and is suited for the formation of polyimide patterns.

Abstract: An addition type polyimide resin raw material composition having high heat resistance and high corrosion resistance comprising a tetracarboxylic anhydride and/or tetracarboxylic diester compound, diamine compound and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and/or exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic monoester compound; a composition containing a prepreg; a fiber-reinforced polyimide composite prepreg, coating material and paint using them; and a curing method thereof.

Abstract: Copolyetherimides are prepared by the reaction of an alkali metal salt of a dihydroxyaromatic compound with a bis(substituted phthalimide) and a third compound which may be a substituted aromatic ketone or sulfone or a macrocyclic polycarbonate or polyarylate oligomer. The reaction takes place the in presence of a solvent and a phase transfer catalyst having high thermal stability, such as a hexaalkylguanidinium halide. Random or block copolymers may be obtained, depending on the reaction conditions.

Abstract: A method for making polyesterimide varnishes by polycondensing and imidat a mixture of trimellitic anhydride, 4,4'-diamino-diphenyl methane, glycol, dimethyl terephthalate and glycerol or tris(hydroxyethyl) isocyanurate or optionally p,p'-dihydroxy-diphenyl-dimethyl methane, with a transesterification catalyst added, and subsequently dissolving the resulting polyesterimide resin in an organic solvent with a crosslinking catalyst added, characterized by the feature that 2-methyl-1,3-propanediol and/or 2-butyl-2-ethyl-1,3-propanediol is used as the glycol or as one of the glycols.

Abstract: Aromatic polyimide powder wherein a solid portion consisting of a highly heat resistant crystalline aromatic polyimide is covered with a coating layer of an amorphous polyimide, and a process for producing polyimide powder molded bodies by compression molding of the powder. The polyimide powder has satisfactory secondary molding workability, and molding thereof gives molded bodies which retain heat resistance and dimensional stability while having high mechanical strength and elongation.

Abstract: An aromatic polyimide precursor composition advantageously employable for the production of an amorphous aromatic polyimide film having Tg of 300.degree. C. or higher is composed of an aromatic tetracarboxylic acid component and an aromatic diamine component which are dissolved in an organic solvent, in which at least 60 mol. % of the aromatic tetracarboxylic acid component is 2,3,3',4'-bi-phenyltetracarboxylic acid, its monoester or diester of a primary alcohol, or their mixture, and at least 55 mol. % of the aromatic diamine component is 4,4'-diaminodiphenyl ether.

Abstract: A preparation process of isoimide comprising reacting a compound having one or more carboxyl group and one or more amide bond in the same molecule in the presence of a haloiminium salt and basic substance, and a preparation process of isoimide comprising reacting a compound having one or more carboxyl group with a compound having one or more amide bond in the presence of a haloiminium salt and basic substance are disclosed.

Abstract: Novel polyimide copolymers containing ether linkages were prepared by the reaction of an equimolar amount of dianhydride and a combination of diamines. The polyimide copolymers described herein possess the unique features of low moisture uptake, dimensional stability, good mechanical properties, and moderate glass transition temperatures. These materials have potential application as encapsulants and interlayer dielectrics.

Abstract: Disclosed herein is a pattern forming process comprising the steps of coating a substrate with a photosensitive resin composition comprising a polyamic compound having, at each terminal thereof, an actinic ray-sensitive functional group which has substituent groups each having a photopolymerizable carbon-carbon double bond, a photosensitive auxiliary having a photopolymerizable functional group, a photopolymerization initiator, and a solvent to form a film; subjecting the film to pattering exposure; and then developing the thus-exposed film with an alkaline developer or alkaline aqueous solution.

Abstract: A new class of polyarylene co-polymers include repeating units comprising one or more arylene units having the general formula (--Ar--/--Y--).sub.n, where Y is a divalent group chosen from nil, --Z--, --Z--Ph--, and --Ph--Z--Ph--, where Z is a divalent group chosen from the group consisting of --O--, --S--, --NR--, --O(CO)--, --O(CO.sub.2)--,--(CO)NH(CO)--, --NR(CO)--, phthalimide, pyromellitimide, --CO--, --SO--, --SO.sub.2 --, --P(O)R--, --CH.sub.2 --, --CF.sub.2 --, and --CRR'--; Ph is phenylene (ortho, meta or para); and n is greater than 4. The co-polymers are useful as molding resins, and composite matrix resins, and where Ar is heteroarylene as ion exchange resins.

Abstract: A rigid, aromatic polyimide composition prepared using a solution imidization process from an aromatic tetracarboxylic dianhydride and a diamine which is greater than 60 mole % to about 85 mole % p-phenylene diamine and 15 mole % to less than 40 mole % m-phenylene diamine exhibits exceptional tensile properties and thermal oxidative stability.

Abstract: A method for synthesizing 1,4-bis(4-aminophenoxy)naphthalene and a series of polyamides, polyimides and copoly(amide-imide)s derived from the said compound is disclosed. These polymers possess excellent thermal stability and mechanical strength.

Abstract: In a method of synthesis of polybenzoxazole and polybenzothiazole precursors, a dicarboxylic acid or a dicarboxylaic acid ester is reacted with a bis-o-aminophenol or bis-o-aminothiophenol in a suitable solvent in the presence of an activating reagent having the following structure: ##STR1##

Abstract: Disclosed is a process which comprises reacting a polyimide precursor with borane. Also disclosed is a thermal ink jet printhead containing a layer comprising the product of this reaction.

Abstract: New photosensitive polyamic acid precursors are disclosed which have the formula: ##STR1## where Z is a tetravalent organic radical which contains at least one aromatic ring, Z' is a divalent organic radical which contains at least one aromatic ring, and R* is a photo polymerizable group. Particularly preferred compounds include BPDA-PDA and BPDA-ODA polyamic acid precursors. The precursor compositions within the practice of this invention are i-line, g-line, and i-/g-line active and show good photoresolution. The films formed exhibit excellent self-adhesion and adhesion to glass ceramic and silicon wafer substrates have low internal stress, a very low degree of solvent swelling, high thermal stability, and excellent mechanical properties such as high modulus/tensile strength and high elongation at break.

Abstract: Polyimide copolymers were prepared by reacting different ratios of 3,4'-oxydianiline (ODA) and 1,3-bis(3-aminophenoxy)benzene (APB) with 3,3',4,4'-biphenylcarboxylic dianhydride (BPDA) and endcapping with an effective amount of a non-reactive endcapper. Within a narrow ratio of diamines, from .sup..about. 50% ODA/50% APB to .sup..about. 95% ODA/5% APB, the copolyimides prepared with BPDA have a unique combination of properties that make them very attractive for various applications. This unique combination of properties includes low pressure processing (200 psi and below), long term melt stability (several hours at 390.degree. C.), improved toughness, improved solvent resistance, improved adhesive properties, and improved composite mechanical properties.

Abstract: This invention provide an adhesive tape and a liquid adhesive for electronic parts having sufficient thermal resistance and reliability. The adhesive tape comprises an adhesive layer composed of at least a polyimide comprising the repeating units represented by the formulas (1) and (2), provided on surface of a heat resistance film or a release film: ##STR1## wherein X is --SO.sub.2 -- and/or --C(.dbd.O)--OCH.sub.2 CH.sub.2 O--C(.dbd.O)--, Ar is a divalent group containing aromatic rings, and R is an alkylene group having 1 to 10 carbon atoms or --CH.sub.2 OC.sub.6 H.sub.4 --, and n means an integer of 1 to 20.

Abstract: A solvent-soluble siloxane polyimide comprising a copolymer obtained by reaction of a diamine compound mixture comprising a diaminopolysiloxane and an alicyclic diamine with an aromatic tetracarboxylic acid anhydride, followed by polyimidization reaction of the resulting polyamic acid forms a heat-resistant adhesive by adding an epoxy resin, a diamine-based curing agent and an organic solvent thereto, The formed adhesives show a distinguished heat-resistant adhesiveness when the resulting siloxane polyimide soluble in ordinary organic solvents is used as a main component of the adhesive for bonding between a base material and a copper foil of a flexible printed substrate. By further addition of a fluorinated resin to the heat-resistant adhesive, the adhesiveness can be more improved.

Abstract: An aromatic polycarbodiimide containing a siloxane bond in the polymer main chain thereof.The polycarbodiimide can adhere at a low temperature in a short time and has a high heat resistance. The polycarbodiimide has a good adhesive property to an adherend such as semiconductor elements, has a low hygroscopic property and is excellent in the storage stability. Therefore, the polycarbodiimide can be stored for a long period of time at normal temperature.

Abstract: A process for inducing pre-tilt in alignment of a liquid crystal medium comprising exposing at least one optical alignment layer, comprising anisotropically absorbing molecules and hydrophobic moieties, to polarized light; the polarized light having a wavelength within the absorption band of said anisotropically absorbing molecules; wherein the exposed anisotropically absorbing molecules induce alignment of the liquid crystal medium at an angle + and -.theta. with respect to the direction of the polarization of the incident light beam and along the surface of the optical alignment layer, and induce a pre-tilt at an angle .PHI. with respect to the surface of the optical alignment layer and applying a liquid crystal medium to said optical alignment layer, is described. The invention also is directed to liquid crystal display elements made by the process of the invention and to novel polyimide compositions that are useful as optical alignment layers in the invention.

Abstract: A polyimide alignment film based on pyromellitic dianhydride and a bis(4-aminophenoxy) aromatic compound, such as 1,3-bis(4-aminophenoxy)benzene or 1,4-bis(4-aminophenoxy)benzene, providing low tilt angles of from 1 to 2 degrees when used in liquid crystal displays.

Abstract: A process for inducing pre-tilt in alignment of a liquid crystal medium comprising exposing at least one optical alignment layer, comprising anisotropically absorbing molecules and hydrophobic moieties, to polarized light; the polarized light having a wavelength within the absorption band of said anisotropically absorbing molecules; wherein the exposed anisotropically absorbing molecules induce alignment of the liquid crystal medium at an angle + and -.theta. with respect to the direction of the polarization of the incident light beam and along the surface of the optical alignment layer, and induce a pre-tilt at an angle .PHI. with respect to the surface of the optical alignment layer and applying a liquid crystal medium to said optical alignment layer, is described. The invention also is directed to liquid crystal display elements made by the process of the invention and to novel polyimide compositions that are useful as optical alignment layers in the invention.

Abstract: This invention provides a polyimide precursor solution having high concentration and low viscosity and a production process thereof, and polyimide coatings and films having excellent physical properties obtained therefrom and a production process thereof. Particularly, it relates to a polyimide precursor solution which contains a salt of a specific diamine with a specific tetracarboxylic acid, as its solute; to a process for the production of the polyimide precursor solution, which comprises allowing 1 mole of a specified diamine to react with 0.3 to 0.9 mole of a specific tetracarboxylic acid dianhydride, thereby obtaining a diamine, and subsequently adding 0.95 to 1.

Abstract: This invention relates to a wiring structure having metal wiring layers and polyimide layers. An object of this invention is to overcome problems caused by oxidation of a metal surface, such as an increase in the resistance of wiring and a reduction in insulation, by preventing a reaction between a metal of the wiring layers, such as copper, and carboxyl groups of polyamic acid which make up the polyimide layers. In the wiring structure according to the present invention, the polyimide layers have been formed by heating and curing a resin composition which comprises a polyimide precursor, an amine compound and an organic solvent.

Abstract: An aromatic polyimide film in the form of a continuous tape having a thickness of 50 to 125 .mu.m favorably employed for manufacture of electric circuit is composed of a biphenyltetracarboxylic acid recurring unit and a p-phenylenediamine recurring unit. The polyimide film has the following characteristics: a tensile strength of not lower than 30 kg/mm.sup.2 ; a tensile modules of not lower than 500 kg/mm.sup.2 ; a linear expansion coefficient of not higher than 2.5.times.10.sup.-5 cm/cm/.degree.C.; a heat shrinkage ratio of not higher than 0.05%; a low curling having a maximum curling of not higher than 3 mm for a disk of diameter of 86 mm; and a uniform thickness having a maximum rate of inclination of not more than 3 .mu.m per 10 mm.

Abstract: A photosensitive resin composition comprising, as its main ingredient, a poly(amic acid) resin constituted of a diamino compound represented by formula: ##STR1## and optionally used other diamino compound and a tetracarboxylic acid dianhydride as its constituent monomers and/or a poly(amic acid) ester resin obtained by esterifying said poly(amic acid) resin and/or a polyimide resin obtained by a dehydrating or alcohol-eliminating ring-closure reaction of said poly(amic acid) resin or poly(amic acid) ester resin has an excellent developability and a high film strength and can form a relief patter of low thermal expansion.

Abstract: A new diamine, 2,2'-dimethyl-4,4'-bis(4-aminophenoxy)-biphenyl was synthesized and used to prepare high performance engineering plastics by polycondensation. The new diamine as shown in the following formula has a noncoplanar 2,2'-disubstituted biphenylene and a flexible aryl units: ##STR1## The engineering plastics disclosed in the present invention includes polyamides, polyimides and poly(amide-imide)s.

Abstract: A polyimide fiber having textile physical property characteristics and the process of melt extruding same from a polyimide powder. Polyimide powder formed as the reaction product of the monomers 3,4'-ODA and ODPA, and endcapped with phthalic anhydride to control the molecular weight thereof, is melt extruded in the temperature range of 340.degree. C. to 360.degree. C. and at heights of 100.5 inches, 209 inches and 364.5 inches. The fibers obtained have a diameter in the range of 0.0068 inch to 0.0147 inch; a mean tensile strength in the range of 15.6 to 23.1 ksi; a mean modulus of 406 to 465 ksi; and a mean elongation in the range of 14 to 103%.

Abstract: Polyimides satisfying the requirements (a), (b) and (c) among the requirements described below, polyimides satisfying the requirements (b), (c) and (d), and polyimides satisfying the requirements (a), (b), (c) and (d) are excellent in transparency, isotropy and resistance to cracking (no crack is formed in the formation of a multilayer film, so that the multilayer formation is easy, namely, the polyimides are good in processability) and can give optical parts excellent in optical characteristics:(a) the difference between the refractive index in TE mode and that in TM mode is 0.02 or less,(b) the glass transition temperature (Tg) is 250.degree. C or higher,(c) the optical transmission loss at a wavelength of 0.7 to 1.6 .mu.m is 1 dB/cm or less, and(d) the fluorine content is 22.6% by weight or less.

Abstract: Stripping fingers for use in a copying machine formed from a resin composition comprising 50-90% by weight of a thermoplastic polyimide resin, and 10-50% by weight of titanium oxide whiskers or zinc oxide whiskers. They may be formed from a resin composition comprising 50-80% by weight of a thermoplastic polyimide resin, 10-40% by weight of titanium oxide whiskers or zinc oxide whiskers, and 2-15% by weight of aromatic polyamide resin powder.

Abstract: The method for preparing a crosslinked polycarbodiimide according to the present invention comprises reacting a polydicarbodiimide compound with a compound, which has in a molecule thereof two or more hydroxy or mercapto groups, in the presence of an alcoholate of an alkali metal or of an alkaline earth metal. The crosslinked polycarbodiimide obtained according to the method is excellent in heat resistance and mechanical properties.

Abstract: A process for making polyimide-polyamic ester copolymer composition comprisingreacting at least one diamine, a pyromellitic diacid diester compound; at least one other tetracarboxylic diacid diester compound and a selected phosphoramide in the presence of a base catalyst to form a polyimide-polyamic acid ester copolymer.

Abstract: An aromatic polyimide film which is favorably employed for preparing a laminate of an aromatic polyimide film, an adhesive layer, and an electroconductive sheet is made of a polyimide prepared from a tetracarboxylic acid component containing at least 15 molar % of biphenyltetracarboxylic acid (or its dianhydride or ester) and an aromatic diamine component containing at least 5 molar % of phenylenediamine, has a specific edge tearing resistance of 11 to 22 kg/20 mm/10 .mu.m, and contains not more than 0.4 weight percent of a volatile component.

Abstract: Polyetherimide polymers prepared from monomers containing indane moieties are disclosed. The high molecular weight indane polyetherimides are transparent, ductile, and exhibit high glass transition temperatures (>200.degree. C.). In addition, the polyetherimides are thermally stable at high temperatures and exhibit good optical properties making them useful in high temperature processing applications, in the fabrication of optoelectronics devices, and in optical applications.

Abstract: A hydroxy- or mercapto-bearing organic compound is caused to react with a polycarbodiimide compound in the presence of an alcoholate of an alkali metal or of an alkaline earth metal. The carbodiimide linkage in the polymer which results from the above-described reaction is crosslinked.

Abstract: A sliding material and a heat resistant filament which primarily comprises a liquid crystal polyimide, a liquid crystal polyamide or a liquid crystal polyamide-imide copolymer having at least one recurring structural unit selected from the formula (1) and the formula (2) and is excellent in heat resistance, mechanical characteristics and other fundamental properties of polyimides, and relates to significant improvement of heat-resistance by heat-treating the sliding material, the filament and the molded items. The liquid crystal polyamide-imide copolymer which comprises in a polymer molecule 0.05.about.0.95 mole ratio of the recurring structural units of the formula (1) and 0.95.about.0.

Abstract: 18.4 grams of 4,4'-(hexafluoroisopropyridine)diphthalic acid dianhydride and 7.5 grams of 1,4-phenylenediamine dihydrochloride are mixed in a solvent consisting of 80 ml of N-methyl-2-pyrrolidone and 20 ml of dichlorobenzene and are heated at an argon atmosphere to raise its temperature from a room temperature to 170.degree. C. slowly and to be reacted for five hours while an azeotropic dihydration of water which is generated at 170.degree. C. is conducted. After the reaction is completed, a reaction product is precipitated in methanol, the precipitate is washed with methanol and dried at 80.degree. C. FIG. 1 shows the infrared spectra of the reaction product.

Abstract: The physical properties of high performance composites can be tailored by using blends to make the composites. The resulting composites are relatively easy to make and have long-term, high performance capabilities even in harsh service conditions. The blends of the present invention include at least one oligomer having an aromatic, aliphatic, or mixed aromatic and aliphatic backbone from one chemical family and an unsaturated hydrocarbon end cap and at least one polymer from a different chemical family. Upon curing, the oligomer in the blend addition polymerize to form composites possessing advanced properties with respect to those exhibited by the pure oligomer or the pure polymer. Coreactive oligomer blends can be used instead of a pure oligomer to form composites that include addition polymers, block copolymers, and the compatible polymer, thereby further achieving a tailoring of properties in the cured composite. The blends can be prepregged and cured to form composites.

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 a proton (--H) or methyl (--CH.sub.3) and n is an integer ranging from 1 to 4. These polyamide and polyimide exhibit good mechanical performance and processability.

Abstract: A process for inducing pre-tilt in alignment of a liquid crystal medium comprising exposing at least one optical alignment layer, comprising anisotropically absorbing molecules and hydrophobic moieties, to polarized light; the polarized light having a wavelength within the absorption band of said anisotropically absorbing molecules; wherein the exposed anisotropically absorbing molecules induce alignment of the liquid crystal medium at an angle + and -.theta. with respect to the direction of the polarization of the incident light beam and along the surface of the optical alignment layer, and induce a pre-tilt at an angle .PHI. with respect to the surface of the optical alignment layer and applying a liquid crystal medium to said optical alignment layer, is described. The invention also is directed to liquid crystal display elements made by the process of the invention and to novel polyimide compositions that are useful as optical alignment layers in the invention.

Abstract: The present invention relates to a new polyesterimide of the type containing ester repeat functional groups E=--CO--O--, imide repeat functional groups I: ##STR1## and at least one chromophore, characterized in that it contains a quantity of recurrent amide functional groups capable of ring closure to imides which is smaller than or equal to 5 mol % relative to the sum of the imide functional groups and of the amide functional groups capable of ring closure to imides, which are present, and in that the polymerization functional groups consist essentially of E functional groups.This polyesterimide is preferably free from amide functional groups capable of ring closure to imides.One of the processes for obtaining this polyesterimide constitutes another subject-matter of the invention.Such a polymer is advantageously capable of behaving like a material that is transparent and/or active in nonlinear optics.

Abstract: This invention is directed to a polyimide film useful as use applications for electronic materials; a liquid crystal aligning film using the same; a liquid crystal display element provided with the liquid crystal aligning film; and a polyamic acid used as a raw material of the polyimide constituting the polyimide film.The polyimide used for preparing the above polyimide films, consists of a diamine component, the 50% by mol or more based upon the total diamine, of which is a diamine having a core structure having no polar group such as 1,2-bis(4-(4-aminobenzyl)phenyl)ethane, 1,6-bis(4-(4-aminobenzyl)phenyl)hexane, 1,1-bis(4-(4-aminobenzyl)phenyl)heptane, etc., and a tetracarboxylic acid dianhydride, and if necessary, an aminosilicon compound, is used as a liquid crystal aligning film.