Abstract: An object of the present invention is to provide a rotor magnet that is capable of adjusting attraction of magnet that is mounted in a spindle motor, a spindle motor including the same, a recording and reproducing apparatus, and a jig for manufacturing the same, with a simple configuration. A rotor magnet is an approximately annular member that is attached to a rotor hub rotating around a shaft forming a part of a spindle motor. The rotor magnet is magnetized such that magnetization properties of axially top and bottom surfaces of the rotor magnet are different from each other.

Abstract: An object of the present invention is to provide a rotor magnet that is capable of adjusting attraction of magnet that is mounted in a spindle motor, a spindle motor including the same, a recording and reproducing apparatus, and a jig for manufacturing the same, with a simple configuration. A rotor magnet 7 is an approximately annular member that is attached to a rotor hub 6 rotating around a shaft 1 forming a part of a spindle motor 20. The rotor magnet 7 is magnetized such that magnetization properties of axially top and bottom surfaces 7b and 7c of the rotor magnet 7 are different from each other.

Abstract: The photobase generator of the invention is represented by the following formula 1: wherein Ar, R, A+ and X? are as defined in the specification. Since the photobase generator of the formula 1 absorbs ultraviolet lights of relatively long wavelength and is photolyzed to generate a strong base efficiently, a composition containing the photobase generator and an episulfide compound is easily cured by polymerization under ultraviolet irradiation.

Abstract: The photobase generator of the invention is represented by the following formula 1: wherein Ar, R, A+ and X? are as defined in the specification. Since the photobase generator of the formula 1 absorbs ultraviolet lights of relatively long wavelength and is photolyzed to generate a strong base efficiently, a composition containing the photobase generator and an episulfide compound is easily cured by polymerization under ultraviolet irradiation.

Abstract: A ferroelectric liquid crystal cell comprising a ferroelectric liquid crystal having an antiferro-electric phase (S.sub.m C.sub.A.sup.*) or its composition and a pair of substrates having electrodes and holding said liquid crystal or its composition therebetween, characterized in that the layer structure of said liquid crystal in the antiferro-electric phase (S.sub.m C.sub.A.sup.*) has once been changed from a chevron structure to a bookshelf structure by application of a voltage to the electrodes.

Abstract: A process for the production of 2,3,5-trimethylbenzoquinone (TMBQ) from 2,3,6-trimethylphenol (TMP) is described, comprising contacting TMP with oxygen or an oxygen containing gas in a medium of water and an aliphatic alcohol having from 5 to 10 carbon atoms in the presence of catalyst of a copper halogen complex represented by the formula as shown below or a mixture of the copper halogen complex and an alkali metal halide or a mixture of the copper halogen complex, an alkali metal halide and cupric hydroxide and/or cuprous chlorideM.sub.l [Cu(II).sub.m X.sub.n ].sub.pwherein M is an alkali metal or ammonium, Cu(II) is a divalent copper, X is a halogen atom, l is an integer of 1 to 3, m is 1 or 2, n is an integer or 3 to 8, p is 1 or 2, and l+2mp=np. The process is carried out in a batch system, a semi-batch system or in a continuous flow system. The third mentioned catalyst system is most effectively utilized in the semi-batch system.

Abstract: A process for the preparation of 4-hydroxy-2,4,6-trimethylcyclohexa-2,5-diene-1-one from 2,4,6-trimethylphenol is disclosed, comprising reacting 2,4,6-trimethylphenol with an aqueous solution or suspension of hypohalogenous acid or salt thereof in an aqueous medium or mixed medium of water and specific organic solvents. This process enables to prepare 4-hydroxy-2,4,6-trimethylcyclohexa-2,5-diene-1-one, which is a precursor for 2,3,5-trimethylhydroquinone, a starting material for the preparation of vitamin E, by a simplified operation, safely and at high yields.