Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – One component toner
Patent
1981-11-09
1983-07-26
Welsh, John D.
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
One component toner
430110, 4301066, 428405, 428407, 427219, 427221, 252 11, 106308M, 106300, G03G 908, G03G 1309
Patent
active
043954855
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD TO WHICH THE INVENTION BELONGS
The present invention relates to dry toner, particularly to one-component type dry toner used as developer in a copying apparatus or a printer according to an electrophotographic process.
BACKGROUND ARTS OF THE INVENTION
An electrophotographic process is well utilized in a copying apparatus or a printer. In the process, for example, an electrostatic latent image is formed first on a photosensitive medium such as a photosensitive drum and then the electrostatic latent image is visualized by the development with a toner. The visualized image, namely a toner image, can be converted to a copied or printed information by fixing the toner image directly onto the photosensitive medium. However, for the repeated use of the photosensitive medium, it is necessary to transfer the toner image to other transfer medium such as paper. Therefore, the process usually includes a transfer process of the toner image. The transfer utilizes so-called Coulomb force by which polar charge reverse to the toner image, which was given to the transfer medium by corona discharge, pulls the toner of the toner image toward the transfer medium. The toner pulled on the transfer medium is then fixed there by heat or pressure, or both.
Dry toner is a developer used in the above-mentioned development process. It is classified into one-component type and two-component type. The one-component type toner consists of a mixture of resin powder as main part and flow agent which gives a flowability to the resin powder. On the other hand, two-component type toner consists of a mixture of resin powder as main part and magnetizable powder, namely carrier.
The toner development by one-component type toner is carried out by utilizing its own electrostatic induction ability. That is, since the one-component type toner has some electric conductivity, the contrary polar charge to the electrostatic latent image is induced by electrostatic induction when it is brought near the electrostatic latent image. Accordingly, Coulomb force acts between the electrostatic latent image and the toner and the toner is pulled toward the electrostatic latent image.
Thus, in the development process, the one-component type toner must be conductive. Contrariwise, since the transfer utilizes corona discharge as mentioned above, the toner must also be insulative. Namely, the one-component type toner should have a delicate balance of properties: electric conductivity and insulation ability which conflict with each other. In order to always obtain an image of constant density, it is necessary that the balance is stable. However, the property of electric conductivity or insulation ability is nothing else but the problem of the degree of resistivity of the toner. Since the value depends on not only its composition but also largely on the environmental condition, especially humidity of air, it is essentially unstable.
In conventional one-component type toner, silica is used, for example, as flow agent. Since silica particles are very fine and have a large specific surface area in order to increase flowability of the toner, they very readily absorb water. Therefore, it is very difficult to maintain the resistivity of the toner constant and a decrease in flowability of the toner due to absorbed humidity also occurs.
On the other hand, another one-component type toner is known, wherein hydrophobic silica is used as flow agent. All active sites of this type of silica, where water is absorbed, namely hydroxyl (OH) radical at the surface, are chemically blocked with dimethyldichlorosilane, etc. Consequently, the hydrophobic silica has little tendency to absorb water and thus the resistivity of the toner is kept almost constant irrespective of the level of humidity in air. However, since, in this toner, there are no polar OH radicals at the surface of hydrophobic silica flow agent, the flow agent has become neutral and can have no definite polar charge. The resin powder alone gives insufficient polarity to the toner and an admixture with cha
REFERENCES:
patent: 3185777 (1965-05-01), Rheinfrank
patent: 3224993 (1965-12-01), Wynne
patent: 3236639 (1966-02-01), Tomanek et al.
patent: 3349703 (1967-10-01), Varron
patent: 3781207 (1973-12-01), Tamm
patent: 3811880 (1974-05-01), Browning
patent: 3944705 (1976-03-01), Fujioka
patent: 4073980 (1978-02-01), Westdale et al.
patent: 4248950 (1981-02-01), Westdale
Int. Appl. PCT/JP81/00073, Toray Industries, p. 2286, (1981).
Kashiwagi Michio
Nakajima Kiichi
Toray Industries Inc.
Welsh John D.
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