Abstract: A magnetic toner is constituted by at least a binder resin and a magnetic iron oxide. The magnetic iron oxide is characterized by having an Fe(II) content of 18.5-24.1 wt. %, and shows a BET specific surface area of S (m.sup.2 /g) and an X-ray diffraction pattern giving a half-value width W (deg.) of a diffraction peak corresponding to 311 plane of the magnetic iron oxide in spinel structure, the values S and W satisfying: 4.5.times.10.sup.-3 S+0.130.ltoreq.W.ltoreq.4.5.times.10.sup.-3 S+0.160, and 4.5.ltoreq.S.ltoreq.11.0. Alternatively, the magnetic iron oxide is characterized by having a number-average particle size D satisfying a relationship with W of: -0.08D+0.180.ltoreq.W.ltoreq.-0.08D+0.212, and 0.10.ltoreq.D.ltoreq.0.45. The relationship between W and S or D indicates a good crystallinity of the magnetic iron oxide which provides the magnetic toner with a stable performance for a long period of time. The magnetic iron oxide can be obtained through a heating treatment at a temperature of 130.degree.

Abstract: A developer for developing electrostatic images is constituted by toner containing a binder resin and a charge controller. The charge controller comprises an arylurea compound which is an arylurea having at least one electron-attracting group or electron-donating group, or a polyarylurea including such an arylurea as a recurring unit. The arylurea compound is substantially colorless and can have stable but different levels of triboelectric chargeability depending on the substituents.

Abstract: A toner for developing an electrostatic image is provided as a pulverized mixture including a binder resin and a colorant. The binder resin is characterized by a molecular weight distribution on a GPC chromatogram of its tetrahydrofuran (THF)-soluble resin content including below 15% of a resin component in a molecular weight region of at most 5000 and at least 5 wt. % of a resin component in a molecular weight region of at least 5.times.10.sup.6 and showing a main peak in a molecular weight region of 5000 to 5.times.10.sup.6. The THF-soluble resin component in the molecular weight region of at least 5.times.10.sup.6 is extremely enriched during a melt-kneading step during the toner production, so as to effectively prevent toner flowout from a member for cleaning a fixing roller.

Abstract: A guanidine type compound has the following formula: ##STR1## wherein R.sup.1 to R.sup.8 are each a hydrogen atom, an alkyl group, an amino group, an alkoxy group, a substituted or umsubstituted aryl group, and R.sup.1 and R.sup.8 may be the same as or different from each other and together may form a ring with the adjacent substituents; X is a halogen atom, a hydroxyl group or an alkoxy group; and m and n are each an integer having a value of 1 to 8. The guanidine compound is employed in a toner for electrostatic development and the toner can be used in an electrophotographic apparatus including a facsimile apparatus for receiving image information from an electrophotographic copier.

Abstract: A toner for developing an electrostatic image comprises a binder resin and a dimer of a diarylguanidine type compound. The dimer is represented by the general formula (I) below: ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.1 a, R.sup.2 a, R.sup.3 a, R.sup.4 a, R.sup.5 a, and R.sup.6 a are respectively a hydrogen atom, an alkyl group, an amino group, an alkoxy group, or an aryl group which may have a substituent, and may be the same or different from each other; adjacent groups may be linked together to form a ring; and A is a linking group.

Abstract: A mechanism for opening and closing an openable apparatus has a body consisting of a first body portion and a second body portion. The first body portion is rotated about a pivotal axis between the closed position and the fully opened position. An arcuated gear portion having a center falling on the pivotal axis is provided. A one-way damper mechanism is connected to the gear portion directly or via a transmission gear and comprises a rotary gear rotated in cooperation with the opening and closing movements of the first body portion and a rotational speed control device for controlling the rotational speed of the first body portion when the first body portion is closed. In cooperation with the movement of the first body portion between the closed position and the fully opened position, the rotary member is rotatable about the pivotal axis between a first position at which the first body portion is closed and a second position at which the first body portion is fully opened.

Abstract: A toner for developing an electrostatic image comprises a binder resin and a dimer of a diarylguanidine type compound. The dimer is represented by the general formula (I) below: ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.1 a, R.sup.2 a, R.sup.3 a, R.sup.4 a, R.sup.5 a and R.sup.6 a are respectively a hydrogen atom, an alkyl group, an amino group, an alkoxy group, or an aryl group which may have a substituent, and may be the same with or diffrent from each other; adjacent groups may be linked together to form a ring; and A is a linking group.