Abstract: A process for producing an adhesive film includes laminating an adhesive layer containing thermoplastic polyimide onto at least one surface of a highly heat-resistant polyimide layer by coextrusion casting method, wherein a chemical dehydrator and a catalyst are contained in a precursor solution of the highly heat-resistant polyimide and/or a solution containing either the thermoplastic polyimide or a precursor of the thermoplastic polyimide.

Abstract: A process includes the steps of: casting or coating a polyamic acid organic solvent solution on a support and drying the polyamic acid organic solvent solution thereon, so as to form a partially cured and/or partially dried polyamic acid film; dipping the polyamic acid film in tertiary amine or a solution of tertiary amine, or coating tertiary amine or a solution of tertiary amine on the polyamic acid film; and drying the film while imidizing the polyamic acid. In another process, a chemical converting agent and a catalyst are mixed in an organic solvent solution of polyamic acid. After casting and heating the mixture on a support, a partially cured and/or partially dried polyamic acid film is detached from the support. The film contains, with respect to the remaining volatile component, not less than 50 parts of catalyst, not more than 30 parts of solvent, and not more than 20 parts of chemical converting agent and/or a chemical converting agent derived component.

Abstract: The present invention provides a flexible printed circuit which is free from curl, torsion and warpage due to temperature change and excellent flexural endurance. By using polyimide film having an average coefficient of thermal expansion of 1.0×10?5 to 2.5×10?5 cm/cm/° C. in a temperature range of 100° C. to 200° C. and a stiffness value of 0.4 to 1.2 g/cm as the base film for the flexible printed circuit, a flexible printed circuit having excellent thermal dimensional stability and flexural endurance can be prepared.

Abstract: A polyamide acid solution and/or gel film is subjected to at least any one of the following processes: addition of a semiconducting inorganic filler, addition of a conductivity imparting agent, and formation of a conductive film. Thereafter, the polyamide acid contained in the polyamide acid solution or gel film is imidized. Thus, the obtained semiconducting polyimide film has surface and volume resistances satisfactorily controllable and less dependent on voltage, excellent mechanical properties, and a high elongation rate.

Abstract: The present invention provides a flexible printed circuit which is free from curl, torsion and warpage due to temperature change and excellent flexural endurance. By using polyimide film having an average coefficient of thermal expansion of 1.0×10−5 to 2.5×10−5 cm/cm/° C. in a temperature range of 100° C. to 200° C. and a stiffness value of 0.4 to 1.2 g/cm as the base film for the flexible printed circuit, a flexible printed circuit having excellent thermal dimensional stability and flexural endurance can be prepared.

Abstract: A process includes the steps of: casting or coating a polyamic acid organic solvent solution on a support and drying the polyamic acid organic solvent solution thereon, so as to form a partially cured and/or partially dried polyamic acid film; dipping the polyamic acid film in tertiary amine or a solution of tertiary amine, or coating tertiary amine or a solution of tertiary amine on the polyamic acid film; and drying the film while imidizing the polyamic acid. In another process, a chemical converting agent and a catalyst are mixed in an organic solvent solution of polyamic acid. After casting and heating the mixture on a support, a partially cured and/or partially dried polyamic acid film is detached from the support. The film contains, with respect to the remaining volatile component, not less than 50 parts of catalyst, not more than 30 parts of solvent, and not more than 20 parts of chemical converting agent and/or a chemical converting agent derived component.

Abstract: A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 &mgr;m, a density of about 1 to about 6 pounds/ft3 and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bonded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/ft3 and a compression strength of about 100 to about 1400 pounds/in2.

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: 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: A mechanically undensified aromatic polyimide foam is made from an aromatic polyimide precursor solid residuum and has the following combination of properties: a density according to ASTM D-3574A of about 0.5 pounds/ft.sup.3 to about 20 pounds/ft.sup.3 ; a compression strength according to ASTM D-3574C of about 1.5 psi to about 1500 psi; and a limiting oxygen index according to ASTM D-2863 of about 35% oxygen to about 75% oxygen at atmospheric pressure. The aromatic polyimide foam has no appreciable solid inorganic contaminants which are residues of inorganic blowing agents. The aromatic polyimide which constitutes the aromatic polyimide foam has a glass transition temperature (Tg) by differential scanning calorimetry of about 235.degree. C. to about 400.degree. C.; and a thermal stability of 0 to about 1% weight loss at 204.degree. C. as determined by thermogravimetric analysis (TGA).

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 shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 .mu.m, a density of about 1 to about 6 pounds/ft.sup.3 and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bonded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/ft.sup.3 and a compression strength of about 100 to about 1400 pounds/in.sup.2.

Abstract: A shaped article composed of an aromatic polyimide has a hollow, essentially spherical structure and a particle size of about 100 to about 1500 .mu.m, a density of about 1 to about 6 pounds/ft.sup.3 and a volume change of 1 to about 20% by a pressure treatment of 30 psi for 10 minutes at room temperature. A syntactic foam, made of a multiplicity of the shaped articles which are bounded together by a matrix resin to form an integral composite structure, has a density of about 3 to about 30 pounds/ft.sup.3 and a compression strength of about 100 to about 1400 pounds/in.sup.2.