Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1997-12-22
1999-12-28
Goodrow, John
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
528272, G03G 9087
Patent
active
060079584
DESCRIPTION:
BRIEF SUMMARY
POLYESTER RESIN FOR FULL COLOR TONER
1. Technical Field
The present invention relates to a polyester resin for a full color toner used for electrophotography, electrostatic printing and the like.
2. Background Art
Methods for obtaining images through an electrostatic charge generally involve development of an electrostatic image formed on a photosensitive drum using toner which has previously been electrostatically charged by friction, and then fixing the image. The fixing is accomplished by anchoring the toner image, obtained by development, using a heated fixing roller under pressure. To obtain color images, the colors must be produced and fixed by adhering toner of about 4 different colors onto transfer paper during the developing process described above, and then melting and combining each of the different color toners with silicone oil-coated rollers during a fixing process. In such development processes it is desirable for the toner to have blocking resistance to prevent its solidification during storage, and to have image stability to allow stable images in the development step, as well as a fixing property for the fixing step and, naturally, a coloring property.
Conventionally, it has been strongly desirable for full color toner resins to exhibit a performance suitable for obtaining color images with toners of different colors, including colorability of the fixed images and a sharp melt property for more efficient colorability and fixability onto paper or OHP. Recently, with the demands for high-speed machines and extended running periods, an improvement in resin strength has been a desired goal to prevent reduction in image density due to filming of the toner. Polyester resins have been widely used in the past as a means of countering these problems, through the mechanism of lowering both the molecular weight and the softening temperature of the resin for the sharp melt property and fixing property. Such resins, however, have low strength and poor filming properties when used for a toner, causing problems which include a lack of charge stability and poor image stability. Attempts have therefore been made to vary the monomer compositions of the resins or to employ crosslinking agents, and such efforts have succeeded in solving those problems to a certain degree. However, in systems employing crosslinking agents, differences in the melt viscosities and molecular weight distributions of resins have led to adverse effects on the fixing property in cases where the fixing speed is higher or the fixing strength is adapted to lower temperatures.
For these reasons, there has been a strong demand for resins with a sharp melt property, a fixing property and a coloring property which have traditionally been required, as well as improved filming resistance without loss of blocking resistance.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a polyester resin for a full color toner to be used for electrophotocraphy, electrostatic printing and the like, which has an excellent fixing property and coloring property as well as improved filming resistance without loss of blocking resistance.
As a result of diligent research regarding the balance between the molecular weights, softening temperatures and melt viscosities of polyester resins employing trace amounts of crosslinking agents, the present inventors have completed the present invention upon the discovery of a polyester resin for a full color toner which not only has a sharp melt property, a fixing property and a coloring property but also has excellent filming resistance, while maintaining the excellent blocking resistance inherent in polyester resins.
Thus, the present invention provides a polyester resin for a full color toner which comprises a) from 0.5 to 5% by mole, based on all the acid components, of a tribasic or higher carboxylic acid component and/or a trihydric or higher alcohol component, b) at least 95% by mole, based on all the acid components, of a dibasic carboxylic acid component, c) from 10 to 80% by mole,
REFERENCES:
patent: 4980448 (1990-12-01), Tajiri et al.
patent: 5057596 (1991-10-01), Kubo et al.
patent: 5153301 (1992-10-01), Tajiri et al.
patent: 5270436 (1993-12-01), Kubo et al.
patent: 5276127 (1994-01-01), Takyu et al.
patent: 5409989 (1995-04-01), Ito et al.
patent: 5807654 (1998-09-01), Kubo et al.
Derwent Abstract, AN 94-189039, JP 06 128 367, May 10, 1994.
Ito Hirokazu
Iwasaki Hitoshi
Tajiri Noriyuki
Goodrow John
Mitsubishi Rayon Company Ltd.
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