The present invention is directed to a polyimide resin comprising a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A contains a structural unit (A-1) derived from 4,4-(hexafluoroisopropylidene)diphthalic anhydride, and the structural unit B contains a structural unit derived from an aliphatic diamine, a polyimide resin composition comprising the polyimide resin and inorganic nanoparticles, and a polyimide film comprising the polyimide resin or the polyimide resin composition. Provided are a polyimide resin and a polyimide resin composition, each of which can form a film having not only a heat resistance, and colorlessness and transparency but also low water absorption properties, and a polyimide film.

Aspects of the present disclosure provide for bridgehead-substituted triptycene-based diamines and methods of making bridgehead-substituted triptycene-based diamines.

A gas separation membrane includes a gas separation layer containing a polyimide compound, and the polyimide compound has a repeating unit represented by Formula (I). The gas separation module, the gas separation device, and the gas separation method are obtained by using the gas separation membrane,

##STR00001##

R.sup.a represents a specific tetravalent group, R.sup.b represents a trivalent group having a specific ring, X.sup.a represents a specific substituent, and X.sup.b represents a hydrogen atom or a substituent. A polyimide compound represented by Formula (I-b) or (I-c),

##STR00002##

R.sup.a represents a specific tetravalent group, R.sup.c represents a specific divalent group, A.sup.a, A.sup.b, A.sup.c, and X.sup.b represent a hydrogen atom or a substituent, and X.sup.c and X.sup.d represent a specific substituent.

A method is provided for producing polyimides by polycondensation of previously produced stoichiometric salts from polycarboxylic acids or their polyanhydrides and polyamines by heating the salts for dehydration. In the method, a) an aqueous solution of a water-soluble stoichiometric salt is produced from polycarboxylic acid and polyamine; b) the aqueous solution undergoes a processing step; and c) the salt contained in the solution is simultaneously or subsequently polycondensed, by heating to form a polyimide.

A monomer represented by Chemical Formula 1-1

##STR00001##

wherein in Chemical Formula 1-1, Z, L.sup.1, L.sup.2, R.sup.1 to R.sup.6, n, m, p, and a to f are the same as defined in the detailed description.

The present invention relates to a polyimide precursor and a lithography pattern formed by the same. The polyimide precursor has a repeating unit having a structure of formula (I):

##STR00001## in the formula (I), Ar represents a tetravalent group derivated from a tetracarboxylic dianhydride compound; R.sub.1 represents a divalent group derivated from a diamine compound; and R.sub.2 independently represent a thermal-crosslinking group, a photosensitive-crosslinking group, or a hydrogen atom. The polyimide precursor has an excellent pattern-forming ability.

A polyamide-imide material comprises an amidophenyl-ethyl-imide moiety or alternatively an imidophenyl-ethyl-amide moiety as depicted in formulas (I) or (II) in the disclosure. The polyamide-imide material can have selected mechanical properties, such as a tensile modulus between at least 3.5 GPa and at least 7.8 GPa, a glass transition temperature between at least 180? C. and at least 305? C., an elongation at break of a film of the polyamide-imide material having a thickness of 25 micrometer (?5 micrometer) of not more than 15%, or a folding endurance of the film over a pin having a radius of 1 mm between at least 10,000 folds and at least 1,000,000 folds. The polyamide-imide film can have high transparency of visible light, a low yellow index, and a low haze.

A method for producing a polyimide resin powder, which involves reacting a tetracarboxylic acid component containing a tetracarboxylic dianhydride and a diamine component containing an aliphatic diamine in the presence of a solvent containing an alkylene glycol solvent of formula (1). In formula (1), Ra.sub.1 represents a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms, Ra.sub.2 represents a linear alkylene group having from 2 to 6 carbon atoms, and n represents an integer of 1 to 3. The reacting produces a solution containing a polyimide resin precursor. This solution is then heated at an average heating rate of 0.5 to 8? C./min in a temperature range of 70 to 130? C. to imidize the polyimide resin precursor to produce the polyimide resin powder in the solution with a solid content concentration of 15 to 25% by mass.

##STR00001##

Provided is a resin composition that has a low viscosity before curing, and is capable of being turned into a cured product having superior dielectric properties (low relative permittivity and low dielectric tangent), a low elastic modulus and also an excellent heat resistance. The resin composition is a heat-curable citraconimide resin composition containing: (A) a citraconimide compound having a saturated or unsaturated divalent hydrocarbon group(s) having 6 to 100 carbon atoms; (B) an epoxy resin having at least two epoxy groups in one molecule; and (C) a reaction promoter,
wherein a mass ratio between the components (A) and (B) is (A):(B)=99:1 to 1:99.

Provided is a polyimide powder composition containing a thermoplastic polyimide resin powder (A) and silica particles (B) having a volume average particle size D50 of 90 nm or less.