Abstract: A composite film having an excellent heat resistance is disclosed. The composite film according to the present invention comprises a substrate film and polyimide membrane(s) formed on at least one surface of the substrate film, which polyimide membrane(s) is(are) prepared by applying a solution of a solvent-soluble polyimide whose main chain is formed by polycondensation of one or more tetracarboxylic dianhydrides and one or more diamines and by drying the solution. The solvent-soluble polyimide comprises bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride as at least a part of the tetracarboxylic dianhydride(s) and/or at least one of 3,5-diaminobenzoic acid and a diaminosiloxane derivative as at least a part the diamine(s).

Abstract: Aromatic diamines having a carboxylic acid group and various other diamines are reacted with aromatic tetracarboxylic dianhdyrides in organic polar solvents to provide polyimides. Polyimide compositions for electrodeposition which comprise the neutralized salts of the polyimides, water and poor solvents for the polyimides have good keeping quality and when electrodeposited on electrically conductive materials, can form polyimide coats that have high levels of appearance, smoothness and denseness while exhibiting good physical and chemical characteristics in such aspects as heat resistance, electrical insulation and chemical resistance.

Abstract: Polyimide soluble in an organic polar solvent was prepared by heating the solution in the presence of a binary catalyst having low boiling point. Block copolyimides consisting of more than three components were prepared by the sequential addition process in the presence of the binary catalyst. Polyimide resins were prepared without the separation of polyimides and catalysts because of evaporating consequently catalysts and solvent. The binary catalyst comprise one compound selected from .gamma.-valerolactone and crotonic acid, and one compound selected from pyridine and N-methylpyrrolidone.

Abstract: A tri-component polyimide copolymer and the process of preparing the copolymer are disclosed. A mixed reaction medium or solvent system comprising phenol and at least one compound of resorcinol, 1,6-dimethyl phenol and 4-methoxy phenol is used to produce the copolymer by direct imidization without isolating or purifying the imide oligomer as an intermediate.

Abstract: A polyimide resin composition with outstanding heat resistance and mechanical properties is disclosed, along with a novel method of its preparation. A tetracarboxylic acid or its derivative and an aromatic diamine are dissolved in a solvent system of mixed phenols and are both polymerized and imidized on one step.

Abstract: A novel class of polyimides useful in making semipermeable membranes for gas separation is synthesized by the reaction of 4,4'-[hexafluoroisopropylidene]-bis-[phthalic anhydride] (6FDA) with 3,7-diamino-2,8-dimethyldiphenylenesulfone (AMPS). In lieu of the two methyl groups the diamine may be substituted by H or C.sub.2-4 alkyl. Membranes made from the polyimides have high permeability for CO.sub.2 from mixtures containing CO.sub.2 and other gases such as CH.sub.4 and have commercially acceptable selectivity.

Abstract: A lawn mower comprises a vehicle body, a cutting unit mounted below the vehicle body, a grass catcher mounted rearwardly of the vehicle body, and a discharge duct extending between the cutting unit and the catcher for transmitting grass clippings from the cutting unit to the catcher. The catcher defines an opening at which a lid member is removably mounted, the lid member includes a coupler opening for coupling to a discharge opening of the discharge duct and an air vent around the coupler opening. The catcher is switchable between a sideways turned posture in which the coupler opening is coupled to the discharge opening and an upright posture in which the coupler opening is directed upwardly.

Abstract: A drive transmission structure for a tractor comprising a belt drive system for transmitting power from an engine output shaft to a transmission having a brake mechanism. The belt drive system includes a belt type stepless change speed mechanism having a split pulley assembly and a swing device for swinging the split pulley assembly toward the engine output shaft and the transmission, a first belt for transmitting the power from the engine output shaft to the split pulley assembly, and a second belt for transmitting the power from the split pulley assembly to the transmission. The pulley assembly defines two split pulley sections for engaging the first and second belts, respectively. A control device is provided to change power transmission ratios by actuating the swing device. Further, a tension pulley type clutch mechanism is provided to act on the first belt or the second belt. The brake mechanism and the tension pulley type clutch mechanism are controlled by the clutch and brake control mechanism.

Abstract: A liquid thermal accumulator composition comprising a dicarboxylic acid anhydride, an alcohol and a monoester of the dicarboxylic acid and the alcohol. A process for accumulation of thermal energy utilizing said composition is also disclosed.

Abstract: A running apparatus for an agricultural vehicle comprising an oil stepless change speed device, an oil circuit for an oil pump and an oil motor to actuate the oil stepless change speed device and an accumulator. The accumulator accumulates a surplus of an output pressure of the oil pump when the pressure is higher than a predetermined value and discharges the accumulated pressure when the output pressure of the oil pump is lower than the predetermined value.

Abstract: A biphenyltetracarboxylic ester, particularly, 3,3',4,4'-biphenyltetracarboxylic tetraester, is prepared in an increased yield by first oxidative coupling, at 140.degree. C. to 260.degree. C., an o-phthalic diester with a molecular oxygen-containing gas, for example, air, in the presence of a catalyst comprising predetermined amounts of a Pd salt, a basic bidentate ligand compound, and a Cu salt to convert a portion of the o-phthalic diester to the corresponding biphenyltetracarboxylic ester and by additionally oxidative coupling in one or more steps, in each step, the remaining portion of o-phthalic diester with a molecular oxygen-containing gas at 140.degree. C. to 260.degree. C. while controlling the composition of the catalyst to an extent such that the entire molar amount of the Pd salt is 0.0001 to 0.01 time that of the o-phthalic diester, the entire molar amount of the ligand compound is 0.5 to 4 times that of the Pd salt and the entire molar amount of the Cu salt is 0.

Abstract: An aromatic polyimide composition usable for producing shaped articles, for example, films, or as varnish, lacquer, or bonding agent, comprises a high molecular weight aromatic polyimide resin which is a polycondensation-imidization product of an aromatic tetracarboxylic acid component comprising 50 molar % or more of 3,4,3',4'-biphenyltetracarboxylic acid, anhydride, salt, or ester with an aromatic diamine component including 50 molar % or more of 4,4'-diaminodiphenylether, and which is dissolved in a mixed solvent consisting essentially of 10% by weight or more of a first solvent component selected from naphthol and resorcin and the balance of a second solvent component selected from phenol and cresols.

Abstract: In a process for producing an iodo-aromatic compound which comprises iodinating an aromatic compound having an electron-donating substituent bonded to the benzene ring with iodine in the presence of a solvent, the improvement wherein about 1/2 to about 10 moles, per mole of iodine added to the reaction system, of nitrogen dioxide (NO.sub.2) is added in the form of NO.sub.2 to the reaction system, and the reaction is carried out in the presence of nitrogen dioxide.

Abstract: Disclosed is an improved process for preparing diesters of malonic acid by subjecting ketene, carbon monoxide and an ester of nitrous acid to a liquid phase reaction in an organic solvent, in which the reaction is carried out in the presence of a catalyst of a platinum group metal complex represented by the formula:L.sub.2 MX.sub.2wherein, L represents a ligand selected from the group consisting of triorganophosphines, triorganophosphite and triorganoarsines; M represents a platinum group metal; and X represents a halogen or an acetic acid ion.

Abstract: A tractor for agriculture comprising an engine, a hydraulic stepless speed change mechanism having an output shaft, an input shaft connecting the engine with the hydraulic stepless speed change mechanism and having an extended portion, a PTO shaft connected in association with the extended portion, a running device, a transmission shaft connected in association with the output shaft, and a transmission change mechanism disposed at an intermediate portion of the transmission shaft, said transmission change mechanism being connectable and disconnectable of power transmission from the output shaft to the running device and capable of power transmission from the extended portion to the running device when said power transmission from the output shaft to the running device is cut. The tractor may be running even if the hydraulic stepless speed change mechanism is in trouble.

Abstract: A biphenyltetracarboxylic tetraester, especially, 3,3',4,4'-biphenyltetracarboxylic tetraalkyl ester, is produced by bringing an orthophthalic diester, especially, orthophthalic dialkylester, into contact with a molecular oxygen-containing gas in the presence of a catalyst consisting of a mixture of a palladium salt with 2,2'-bipyridyl or a chelating reaction product of a palladium salt with 2,2'-bipyridyl, so as to promote oxidative coupling of the orthophthalic diester.

Abstract: A biphenyl compound is produced from a corresponding aromatic monocyclic compound at a high yield thereof and a high percent selectivity thereto, by dehydrogenatively dimerizing the aromatic monocyclic compound with molecular oxygen in the presence of oxalic acid together with a organic palladium salt catalyst, under a pressure higher than the atmospheric pressure.

Abstract: A biphenyltetracarboxylic tetraester, especially, 3,3',4,4'-biphenyltetracarboxylic tetraalkyl ester, is produced by oxidative coupling an orthophthalic diester, especially, orthophthalic dialkylester, in a molecular oxygen-containing atmosphere in the presence of a catalyst consisting of a mixture of a palladium salt with 1,10-phenanthroline and/or 2,2'-bipyridyl or a chelating reaction product of a palladium salt with 1,10-phenanthroline or 2,2'-bipyridyl.

Abstract: A polyimide solution is prepared by a process wherein a tetracarboxylic acid ingredient containing at least about 80% by mole of 3,3',4,4'-biphenyltetracarboxylic acid or its functional derivative and an aromatic diamine ingredient containing at least about 50% by mole of 4,4'-diaminodiphenyl ether are polymerized at from about 100.degree. to 300.degree. C. in phenol or a halogenated phenolic compound; the amount of the acid and diamine ingredients being approximately equimolar to each other; whereby polymerization of the tetracarboxylic acid ingredient and the aromatic diamine ingredient is effected while being accompanied by imidation. Preferably, the polymerization accompanied by imidation is effected in a manner such that at least a second half of the polymerization is carried out in a closed reaction system. The resulting polyimide solution is suitable for making therefrom shaped articles, such as films, possessing excellent mechanical properties.

Abstract: An agricultural tractor transmission to which various attachments may be removably affixed as necessary. Such attachments include a super reduction device and a pump for actuating a work implement.