Abstract: The object of the present invention is to provide a polyimide precursor solution having a good coating workability. Another object of the present invention is to provide transfer and fixing parts such as a polyimide seamless belt and the like produced from said polyimide precursor solution. Said polyimide precursor solution is produced by dissolving said polyimide precursor which is a homopolymer or copolymer of a polyamide acid in a solvent mixture of one or more kind(s) of solvent having a lower boiling point under 100° C., and one or more kind(s) of solvent having a higher boiling point of 100° C. or more, wherein said higher boiling point solvent (s) is (are) contained in said solvent mixture in an amount of 5 to 55% by weight.

Abstract: A method for preparing a substrate for a flexible print wiring board having a polyimide based resin layer wherein a solution of a polyimide based resin precursor is directly applied on an electrically conducting material to form a polyimide based resin precursor layer and then the precursor layer is cured by heating to prepare a polyimide based resin layer, characterized in that a solution of a polyimide based resin precursor B, which is one of solutions of two types of polyimide based resin precursors, is directly applied on an electrically conducting material and then, on the resultant layer is applied a solution of a polyimide based resin precursor A which allows resolving the residual strain generated in the polyimide based resin formed by the curing of the above polyimide based resin precursor B.

Abstract: A polyimide precursor fibrid material which comprises a polyimide precursor that forms a polyimide having a property of no thermal melting when subjected to a ring closure reaction and which is substantially free from aprotic polar organic solvents, and polyimide paper, polyimide composite paper and polyimide composite board obtained therefrom. Since the inventive polyimide precursor fibrid material does not contain aprotic polar organic solvents, a polyimide paper product having excellent strength can be obtained from the polyimide precursor fibrid material, and a polyimide composite paper product and a polyimide composite board both consisting of uniformly dispersed components and having excellent strength can be obtained from the polyimide precursor fibrids and other staple fibers.

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.

Abstract: The present invention provides a process for producing a fiber reinforced composite which contains the reinforcing fibers uniformly dispersed therein and therefore has uniformity of strength. The process comprises;preparing an aqueous slurry which comprises reinforcing fibers, water-soluble organic polymers A charged in water and particulate organic polymers,adding thereto water-soluble organic polymers B charged opposite to said organic polymers A in water to flocculate the solid components in said aqueous slurry, andthen removing aqueous medium and molding.

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: A PTC element comprising a conductive sheet of a crystalline polyolefin matrix and a conductive filler, having provided on both sides thereof an electrode of a metallic foil, the PTC element having a resistivity at 20.degree. C. (.rho..sub.20) of not more than 1.8 .OMEGA..multidot.cm, a peak resistivity (.rho..sub.p) of not less than 2.0.times.10.sup.6 .OMEGA..multidot.cm, and a temperature difference ?T.sub.a (0.degree.C.)-T.sub.b (.degree.C.)! of not greater than 10.degree. C., wherein T.sub.a (.degree.C.) is a temperature at which the resistivity is 10.sup.6 times the resistivity at 20.degree. C. (.rho..sub.20) and T.sub.b (.degree.C.) is a temperature at which the resistivity is 10 times the resistivity at 20.degree. C. (.rho..sub.20).

Abstract: The present invention provides a fiber-reinforced porous plastic tube which is essentially composed with fibers having a high tensile modulus such as glass fibers and a matrix resin such as polyethylene, and has continuous pores, and excellent mechanical strength. This porous tube is useful for structural materials in a building and/or construction, filters, diffusing tubes, drain materials and the like.

Abstract: This invention provides a poly(amic acid) solution which does not contain aprotic polar solvents such as DMF, NMP, DMAc, DMSO, as well as a polyimide film obtained therefrom having appropriate flexibility and a small coefficient of linear thermal expansion and a coated material in which the polyimide film is formed on a substrate.More particularly, it provides a poly(amic acid) solution which has an aromatic poly(amic acid) and a tertiary amine as the solute and a water soluble alcohol compound and/or a water soluble ether compound as the solvent and contains substantially no aprotic polar solvent, as well as a polyimide film obtained from the poly(amic acid) solution and a coated material obtained by forming the film on a substrate.

Abstract: A film forming solution which does not require aprotic polar solvents, a porous film of poly(4,4'-oxydiphenylenepyromellitimide) obtained from the film forming solution which has excellent heat and chemical resistances, which is controllable in terms of porosity and pore size of the film and which has excellent electrical characteristics, and a coated material where the porous film is formed on a base material.Particularly, a film forming solution of a precursor of poly(4,4'-oxydiphenylenepyromellitimide) and a mixture of at least three solvents which are poor solvents for the precursor when each solvent is used alone, a porous film of poly(4,4'-oxydiphenylenepyromellitimide) obtained from the film forming solution and a coated material where the porous film is formed on a base material.

Abstract: The present invention provides a composite sheet electrode which has high strength, excellent current collecting properties and which is used efficiently as an active material for an electrode. The electrode has excellent discharge capacities and can be easily formed into an electrode terminal. A cell employing this electrode is also disclosed. The invention also provides a composite sheet electrode having a porosity of 20 to 80% containing 5 to 95% by weight of an active material of an electrode, 1 to 50% by weight of a current collecting material and heat fusible short fibers. The present invention also provides a composite sheet electrode having a porosity of 20 to 80%, which is made up of a composite sheet containing 5 to 95% by weight of an active material as an electrode and 5 to 95% by weight of heat fusible short fibers, as well as a current collecting material layer formed on said composite sheet. The present invention further provides a cell employing the latter-mentioned composite sheet electrode.

Abstract: A polyimide precursor solution which comprises a polyimide precursor and a solvent wherein the polyimide precursor and the solvent are not solated strongly. A process for the production of the polyimide precursor solution, as well as moldings and coatings obtained from the solution.The polyimide precursor solution of the present invention has excellent storage stability, and the solvent can be removed easily at the time of the production of moldings or coatings. According to the process of the present invention, the polyimide precursor solution can be produced easily using simple apparatus and an inexpensive solvent(s) having low toxicity. The polyimide molding obtained from the polyimide precursor solution has excellent uniformity and no residual solvent. The polyimide coating obtained from the polyimide precursor solution has excellent uniformity, no residual solvent and excellent adhesiveness to a base material.

Abstract: This invention provides (1) a granular material of a polyimide precursor, which has excellent solubility in solvents and excellent moldability and from which a polyimide molding having excellent mechanical properties can be produced, (2) a mixture of a granular material of a polyimide precursor with a solvent, in which the polyimide precursor shows excellent storage stability and (3) a process for the production of a granular material of a polyimide precursor, in which a solvent can be easily removed. Particularly provided are a polyimide precursor granular material having an intrinsic viscosity of 0.7 or higher and a polyimide precursor mixture which consists of a polyimide precursor granular polyimide having an intrinsic viscosity of 0.7 or higher and a solvent that does not exhibit a strong-mutual interaction with the polyimide precursor, as well as a process for the production of the polyimide precursor granular material.

Abstract: The present invention provides a carbonaceous material suitable for an electrode of a secondary cell. The carbonaceous material has a specific surface area by BET method of at least 10 m.sup.2 /g and a nitrogen/carbon atom weight ratio of 0.15 to 0.01, and is obtained by heat-treating a polyimide polymer having repeating units represented by: ##STR1## wherein R represents a 4 valent aromatic residue having at least one aromatic ring, of which each 2 valences are bonded with an adjacent carbon atom in the aromatic ring, R' represents a divalent aromatic residue having 1 to 4 aromatic rings and n is an integer of at least 2. The present invention also provides a secondary cell using the above mentioned carbonaceous material as electrode.