Electrophotographic positively chargeable developer containing silica treated with a nitrogen containing silane coupling agent and method of developing

DETAILED DESCRIPTION An object of the present invention is to provide a developing method and a developer and therefore excellent in durability such as continual use characteristic.
Another object of the present invention is to provide a developing method and a developer therefor stable even against environmental changes such as high temperature and high humidity conditions or low temperature and low humidity conditions.
Still another object of the present invention is to provide a developing method and a developer therefor which can overcome various problems concerned with the chargeable toner of the prior art and can be charged evenly and strongly to visualize the electrostatic images and give images of high quality.
According to one aspect, the present invention is characterized as a developing method, which comprises disposing an electrostatic image bearing member which bears an electrostatic image on its surface and a developer carrying member which carries an insulating developer on its surface with a certain gap provided therebetween at a developing section, bringing an insulating developer containing a nitrogen-containing compound to a thickness thinner than said gap on the developer carrying member and transferring said developer onto said electrostatic image bearing member at the developing section to develop the electrostatic image.
Particularly, it is very effective to apply the above developing method for a developing device having a sleeve roller.
Also, the insulating positively chargeable developer of the present invention is characterized by containing a nitrogen-containing compound.
In a specific embodiment, the above nitrogen containing compound takes the form of an A-B conjugate wherein A is phthalocyanine or its derivative and B is a nitrogen-containing heterocyclic ring or its derivative.
In another embodiment, the above nitrogen-containing compound takes the form of a nitrogen-containing silane coupling agent represented by the formula shown below coating fine silica particles: R