Abstract: A wheel cover includes: a cover body having an engagement hole and configured to cover a design face of a wheel; and a cover fastener that is inserted through the engagement hole. A primary attachment member of the cover fastener includes: a supporter that supports a periphery of the engagement hole; a cylindrical portion that is inserted in a hub hole formed in the wheel; a coupler that couples the supporter and the cylindrical portion; and a hook extending from the cylindrical portion to an outer circumferential side of the cylindrical portion, the hook being contactable with an inner circumferential portion of the hub hole at a position spaced apart from an outer circumferential surface of the cylindrical portion. A secondary attachment member of the cover fastener has an insertion portion that is inserted in a space formed between the hook and the outer circumferential surface.

Abstract: A wheel cover includes: a cover body having an engagement hole and configured to cover a design face of a wheel; and a cover fastener that is inserted through the engagement hole. A primary attachment member of the cover fastener includes: a supporter that supports a periphery of the engagement hole; a cylindrical portion that is inserted in a hub hole formed in the wheel; a coupler that couples the supporter and the cylindrical portion; and a hook extending from the cylindrical portion to an outer circumferential side of the cylindrical portion, the hook being contactable with an inner circumferential portion of the hub hole at a position spaced apart from an outer circumferential surface of the cylindrical portion. A secondary attachment member of the cover fastener has an insertion portion that is inserted in a space formed between the hook and the outer circumferential surface.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼ of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: There is provided biphenyltetracarboxylic dianhydride containing biphenyltetracarboxylic monoanhydride in an amount of not more than 0.4%. By using the biphenyltetracarboxylic dianhydride as a raw material, it is possible to produce polyimide or polyamic acid having an increased molecular weight.

Abstract: It is to provide a high purity oxydiphthalic anhydride with which, in production of a polyimide containing an oxydiphthalic anhydride, one having sufficiently high strength can be produced, and an industrially simple process for producing it. A high purity oxydiphthalic anhydride, which has a content of fine insoluble particles having a projected area diameter of from 5 to 20 ?m, of at most 3,000 particles per 1 g, and has a light transmittance at 400 nm of at least 98.5% in a light path length of 1 cm when dissolved in acetonitrile at a concentration of 4 g/L.

Abstract: There is provided biphenyltetracarboxylic dianhydride containing biphenyltetracarboxylic monoanhydride in an amount of not more than 0.4%. By using the biphenyltetracarboxylic dianhydride as a raw material, it is possible to produce polyimide or polyamic acid having an increased molecular weight.

Abstract: To provide a process for producing BPDA whereby high productivity is attained while high purity is maintained. A process for producing biphenyltetracarboxylic acid dianhydride, which comprises heating biphenyltetracarboxylic acid to produce biphenyltetracarboxylic acid dianhydride, characterized in that the heating is carried out at a pressure of from 1×102 Pa to 1.1×105 Pa to a maximum temperature in a range of from 210° C. to 250° C. in such a manner that the temperature rising rate is higher than 50° C./hr for a period of at least ¼0 of the time for the temperature rise from 60° C. to 210° C., and the temperature is maintained to be from 150° C. to 250° C. for from 0.5 to 10 hours.

Abstract: There is provided biphenyltetracarboxylic dianhydride containing biphenyltetracarboxylic monoanhydride in an amount of not more than 0.4%. By using the biphenyltetracarboxylic dianhydride as a raw material, it is possible to produce polyimide or polyamic acid having an increased molecular weight.

Abstract: A method of manufacturing a rust-preventing cover in which sufficient strength during mounting is ensured and which can be easily removed when not needed. The method of manufacturing a rust-preventing cover is carried out by a WFM manufacturing method rather than a conventional DFM manufacturing method. A mixed aqueous solution having paper fibers as a main material thereof is stored in a water tank. A porous rust-preventing cover mold is immersed therein. Then, the mixed aqueous solution is sucked by a vacuum pump. In this way, a paper fiber surface layer, which later becomes a rust-preventing cover, is formed on a surface of a mold main body of the rust-preventing cover mold at portions to which masking has not been applied. By adjusting a suction time of the vacuum pump, a rust-preventing cover of an arbitrary thickness which corresponds to a thickness required during mounting can be obtained.

Abstract: A mounting arrangement of a rust preventive cover which improves a mounting operation of the rust preventive cover by enabling a visual check of a condition of engagement between the rust preventive cover and a dust cover. The rust preventive cover covers a disk rotor provided in a disk brake for a vehicle. The rust preventive cover is mounted to a dust cover provided on an inner side of the disk rotor with respect to the vehicle. A plurality of protruding portions protrude inwardly from a wall of the rust preventive cover. An opening is formed in each of the protruding portions. An engaging portion is formed on an outer end of the dust cover so that the engaging portion engages with the opening.