Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1996-03-12
1998-09-15
Goodrow, John
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
G03G 9087
Patent
active
058076549
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a polyester resin which is useful as dry toner resin to be used for developing electrostatic charged images or magnetic latent images by electrophotography, electrostatic recording, electrostatic printing, etc., as well as to a process for its production and use. More specifically, the present invention relates to a polyester resin for full color toner which is useful in cases where image clarity and precision are required, as well as a process for its production and toner employing it.
BACKGROUND ART
Methods of obtaining perpetual clear images through electrostatic charge involve developing an electrostatic charged image formed on an electrophotosensitive material or electrostatic recording medium, using toner which has previously been electrostatically charged by friction, and then fixing the image. In the case of magnetic latent images, a latent image on a magnetic drum is developed by toner containing a magnetic substance, and then fixed.
The fixing is accomplished either by direct fusion of a developed toner image onto an electrophotosensitive material or electrostatic recording medium, or by transferring a toner image onto paper or film and then fusing it onto a transfer sheet. The toner fusion is accomplished by contact with a solvent vapor, or by pressure and heat. The heating system may be either a non-contact heating system employing an electrical oven or a contact heating system employing a contact roller, but the latter has been mainly used in recent years due to demand for a faster fixing process.
Toner used in dry developing processes include one-component toner and two-component toner. To prepare a two-component toner, first a resin, coloring agent, charge controller and other necessary additives are melted, kneaded and made into a thorough dispersion which is coarsely and then finely crushed, and sorted into prescribed grain size ranges. A one-component toner is prepared in the same manner, though with addition of magnetic iron powder to each of the components of the above-mentioned two-component toner.
The resin, being the major component of the toner mixture, is responsible for most of the required performance of the toner. Thus, for toner production, toner resins must have good dispersability in the coloring agent during the melting/kneading process and good crushability during the crushing process, and for toner use they require a variety of properties, including satisfactory fixation properties, non-offsetting properties, blocking resistance and electrical qualities.
Publicly known resins used for toner production include epoxy resins, polyester resins, polystyrene resins, methacrylic resins and the like, but contact heat fixation systems primarily use styrene and (meth)acrylic acid ester copolymers. Recently, however, attention has been focused on polyester resins because they allow fixation at even lower temperatures and provide excellent polyvinyl plasticizer resistance for the fixed toner images.
Also, in order to obtain color images, the colors must be produced and fixed by adhering 3- or 4-color toner onto transfer paper during the developing process described above, and then melting and mixing each of the components in the fixing process. It is strongly preferred, as mentioned above, that binder resins for full color toner have good mixability during the fixing process, i.e., good melt flowability. However, using binder resins with satisfactory melt flowability results in the problem of an offsetting phenomenon during the fixing process.
Although this offsetting phenomenon may be prevented by crosslinking the binder resin to induce polymerization, such a measure lowers its melt flowability and thus renders it unsuitable as a binder resin for full color toner. Consequently, in order to prevent offsetting when using full color copiers, silicone oil or the like is applied onto the surface of the fixing roller.
In addition, recent emphasis has been placed not only on image properties but also on environmental factors, and the gene
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Iwasaki Hitoshi
Kubo Shinji
Nagai Yoichi
Tajiri Noriyuki
Goodrow John
Mitsubishi Rayon Company Ltd.
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