Abstract: A wheel for light vehicles and a disc member used therein. The wheel comprising a hub, a rim and a pair of disc members detachably coupled with the hub and the rim, wherein the wheel has the advantage of a spoke wheel that it is lightweight and has sufficient strength as well as the advantage of a disc wheel that it has less air resistance when it rotates, and further the wheel can be easily repaired when it is damaged.

Abstract: A separation membrane comprising a soluble aromatic polysulfone having the formula --(X--Y)--, wherein X and Y comprise the constituent unit shown below, and the inherent viscosity (.eta..sub.inh) based on the value of a solution of 0.5 g of the polysulfone dissolved in 100 ml of N-methyl-2-pyrrolidone measured at 30.degree. C. is 0.4 or more: ##STR1## wherein R.sub.1 -R.sub.4 are each either H, CH.sub.3 or C.sub.2 H.sub.5, and R.sub.5 -R.sub.6 are each either H, Cl, or NO.sub.2.

Abstract: In a method of producing mesophase pitch based carbon fibers, including the steps of melt-spinning a mesophase pitch through a nozzle (1) having at least one pair of a counter-bore (2) and a circular capillary (3) to form a pitch fiber and subjecting the pitch fiber to an infusible treatment, a carbonization treatment, and if necessary, a graphitization treatment, to form a carbon fiber, the nozzle has a degree of asymmetry .phi. of from 0.1 to 0.9, .phi. being defined by the following equation .phi.=S.sub.A /S.sub.B, wherein S.sub.A is an area of an inscribed circle in a contour of the cross-section of the counter-bore, which circles is perpendicular to the nozzle axis and has a center on the axis of the capillary and inscribed and S.sub.B is a total area of the cross-section of the counter-bore.

Abstract: An aromatic polyester carbonate comprising structural units represented by the following formulae (A), (B), (C), and (D) and satisfying the following relationship when the mole fractions of the structural units represented by the formulae (A), (B), (C), and (D) are defined as a, b, c, and d, respectively: ##EQU1## and having an inherent viscosity [.eta..sub.inh ] in a solution at a concentration of 0.5 g/dl in p-chlorophenol as a solvent at 50.degree. C. of 1.0 dl/g or higher, or being insoluble in the solvent, and having liquid crystal properties ##STR1## wherein R is the same or different and represent an alkyl, phenyl group or a halogen, and n represents an integer of 0 to 4; ##STR2## X.sup.1 represents a substituted or non-substituted phenyl group, an alkyl group having 3 to 6 carbon atoms or a halogen;X.sup.2 represents --O--, --S--, ##STR3## or --CH.sub.2 --; X.sup.3 may be the same or different and represents an alkyl group, phenyl group, or a halogen; and m represents an integer of 0 to 4.

Abstract: This invention relates to a polymerization reaction apparatus which is composed of a vertical cylindrical vessel, a rotating shaft inside the vessel, a plurality of agitating blades attached to the shaft, and a large number of plate-like heat transfer elements attached to the inner wall of the vessel, disposed radially between the agitating blades, and internally equipped with a passage for a heat transfer fluid, and in which apparatus a polymerizing mass passes through a gap between the rotating shaft, the agitating blades, and a large number of the plate-like heat transfer elements and exchanges heat with a heat transfer fluid circulating inside the plate-like heat transfer elements, effecting uniform removal of the reaction heat or uniform heating of the polymerizing mass and preventing vertical mixing.

Abstract: A process for producing a carbon fiber by subjecting a pitch fiber, obtained by melt spinning a carbonaceous mesophase pitch, to stabilization, followed by a carbonization or graphitization treatment, wherein the stabilization is carried out under an oxidative atmosphere containing 0.1% to 40% by volume of NO.sub.2 and 4% to 40% by volume of H.sub.2 O at a temperature of from 100.degree. C. to 400.degree. C.

Abstract: An expansion injection molding die having a plate forming the die cavity, a backup plate, a core plate, ejector pins inserted through the backup plate and the core plate for separating the molded products from the die cavity, and a gas introducing passage communicating with the pressurized gas source for introducing gas into the die cavity. The plate that has holes through which the ejector pins are injected are formed with hollow portions. In each of the hollow portions, a guide ring is installed so that it is freely movable at least two-dimensionally. A sealing member is installed in an expanded hole portion in the guide ring so that it is in sliding contact with the ejector pin.

Abstract: Polyimide-based separation membranes of this invention are made from polyimides having repeating units of the general formulas (A) and (B) ##STR1## wherein Ar.sub.1 and Ar.sub.3 are tetravalent aromatic radicals containing at least one aromatic ring, Ar.sub.2 is a divalent aromatic radical containing at least one aromatic ring, R.sub.1 and R.sub.2 are organic radicals, R.sub.3 to R.sub.6 are monovalent hydrocarbon radicals, and n is an integer from 1 to 50 at a mole ratio (A)/(B) of 5/95 to 95/5, have high gas permeation coefficients, high mechanical strength, and excellent heat resistance, and are useful for separation and concentration of mixed gases.

Abstract: This invention relates to a method of making ethylbiphenyls by the reaction of biphenyl with polyethylbenzenes or with ethylene and polyethylbenzenes in the presence of a solid acid catalyst and offers advantages of industrial significance such as absence of acidic waste water, no need of costly materials for equipment, catalyst reuse, and adaptability to a fixed-bed flow reaction system suitable for large-scale production.

Abstract: Silicon-modified polyimides of this invention containing a basic structure of the general formula (1) ##STR1## in which R and R' are hydrogen or alkyl, B is the amineless residue of a diamine, and X is divalent radical ##STR2## in which R.sub.1 to R.sub.4 are monovalent hydrocarbon groups with 1 to 6 carbon atoms show excellent heat resistance and solubility in various solvents and are useful for films for orientation of LCD's, junction coating resins for diodes, passivation films for IC's and LSI's, and alpha ray shielding films for VLSI's.

Abstract: The flexible base materials for printed circuits contain, as an insulator, resins of low thermal expansivity having structural units of the general formula (I) ##STR1## in which Ar.sub.1 is a tetravalent aromatic radical, Ar.sub.2 is ##STR2## R.sub.1 to R.sub.8 are lower alkyl groups, lower alkoxy groups, or halogen atoms, identical with or different from each other, and n1 to n8 are integers of from 0 to 4.The flexible base materials for printed circuits curl very little, and possess sufficient adhesive strength, flexibility and dimensional stability.

Abstract: Flexible printed circuit base materials of this invention are composed of at least one layer of polyimide resins of low thermal expansion, at least one layer of polyimide resins of high thermal expansion with a higher linear expansion coefficient than that of the foregoing polyimide resins, and at least one layer of a conductor, highly reliable in dimensional stability to temperature changes, adhesive strength, and flatness after the etching, easy to work with in protection of the circuits made by etching.

Abstract: A heat-resistant unsaturated polyester having a structure represented by the formula (I)--X--Y).sub.m (X--Z).sub.n (I)wherein X represents a structure (A): ##STR1## wherein R represents hydrogen or an alkyl group having 1 or 2 carbon atoms;Y represents a structure (B): --OC--CH.dbd.CH--CO--Z represents a structure: ##STR2## and m and n independently represent a repeating numbers;a mole ratio of Y/Z is 10/90 to 99/1; andthe polyester has an inherent viscosity (.eta. inh) of at least 0.4 dl/g as determined at a temperature of 30.degree. C. in a solution of 0.5 g of the polyester in 100 ml of dimethylformamide.

Abstract: This invention discloses lightweight panels consisting of a honeycomb, boards on both sides, and phenolic foam of a density of 7-20 Kg/m.sup.3 in the cavities of the honeycomb and a method of making a honeycomb core, with the panels characterized by being light, fireproof, fire-resistant, thermally insulating, and of high strength and useful for building panels, particularly for panels in transportation equipment.

Abstract: A method for the hydrogenation of coal tar pitch which comprises subjecting said coal tar pitch containing toluene insolubles to slight hydrogenation in the presence of a hydrogenation catalyst having carried on a refractory inorganic oxide carrier at least one member selected from the class consisting of elemental metals, belonging to Groups VI B and VIII in the Periodic Table and oxides and sulfides thereof, under the conditions of 280.degree. to 400.degree. C. of reaction temperature, 20 to 200 kg/cm.sup.2. G of hydrogen pressure, 0.1 to 10 hr.sup.-1 of LHSV, and 500 to 2,000 Nl/liter of hydrogen to liquid ratio, and a catalyst therefor. The "slight" hydrogenation is hydrogenation to a degree such that the difference of hydrogen to carbon atomic ratio between the untreated coal tar pitch and the hydrogenated coal tar pitch falls in the range of 0.03 to 0.5.

Abstract: A method for treatment of carbon fibers for reinforcement comprises the step of coating or impregnating carbon fibers with an emulsion of epoxy resin having colloidal silica added thereto so as to harden the same. The carbon fibers treated in this way exhibit high bonding strength with respect to a concrete matrix, making it possible to obtain excellent carbon fiber reinforced mortar and concrete.

Abstract: A method for the manufacture of phthalic anhydride by the catalytic oxidation of naphthlene and/or ortho-xylene which comprises contacting a mixed gas containing naphthalene and/or ortho-xylene and a molecular oxygen-containing gas with a catalyst bed comprising a first catalyst packed on the upstream side of the flow of mixed gas and a second catalyst packed on the downstream side of the flow, wherein the first catalyst has carried on a nonporous inactive carrier a catalytically active component composed of 90 to 67% by weight of titanium dioxide, 8 to 30% by weight of vanadium pentoxide, 2 to 5% by weight of a cesium compound and 0.11 to 0.2 of cesium compound/vanadium pentoxide (molar ratio) (calculated as Cs.sub.2 SO.sub.4), and the second catalyst has carried on the nonporous inactive carrier a catalytically active component composed of 94 to 67% by weight of titanium dioxide, 5 to 30% by weight of vanadium pentoxide and not more than 0.

Abstract: A phenolic polymerization inhibitor is recovered from a styrene distillation residue containing the phenolic polymerization inhibitor by a method which comprises extracting the inhibitor from the styrene distillation residue with an oxygen-containing organic solvent having not more than 6 carbon atoms, adding an aromatic hydrocarbon solvent to the oxygen-containing organic solvent phase consequently obtained, and subjecting the resultant mixture to distillation thereby separating the mixture into a solution of the phenolic polymerization inhibitor in the aromatic hydrocarbon solvent and the oxygen-containing organic solvent. The recovered solution is put to use as a polymerization inhibitor either in the unmodified form or in a form separated from the aromatic hydrocarbon solvent.

Abstract: Polyamide-imides of low thermal expansivity having a repeating structural unit of the general formula (I) ##STR1## in which Ar is a tetravalent aromatic group, A is --NHCO--, R1 through R3 are alkyl, alkoxy, or halogen, l, m, and n are integers from 0 to 4, x is 0 or 1, and y is an integer indicating the number of repeating units and in which at least one alkoxy group is present, show improved mechanical (for example, flexibility) and adhesive properties and low water absorption and are useful for the manufacture of flexible base materials for printed circuit boards, etc.

Abstract: A soluble heat-resistant aromatic polyamide having amide bonds at the terminal ends thereof represented by the formula (I):R.sup.1 CO--NH--Y--NH--X).sub.n NH--Y--NHCOR.sup.1 (I)wherein R.sup.1 represents an alkyl group or aromatic group,Y represents ##STR1## wherein R.sup.2 represents hydrogen, methyl, or ethyl, X represents ##STR2## wherein Z represents an aromatic ring which may be substituted with an alkyl group, andn is a recurring unit number; said polyamide having an inherent viscosity (.eta..sub.inh) of at least 0.30 dl/g as measured in a solution of 0.5 g of the polyamide in 100 ml of dimethylacetamide at 30.degree. C.