Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-01-31
2004-11-16
Dote, Janis L. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S107100, C430S109100, C430S109200, C430S109400, C430S111400, C430S120400, C430S137100, C528S087000, C523S402000
Reexamination Certificate
active
06818369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin for a toner for electrostatic image development, a master batch pigment, a toner, a developer, an image forming method, and an image forming apparatus.
2. Description of the Related Art
Image forming apparatuses such as copiers, facsimile machines, printers, and the like have been used everywhere following the increase in the office work. An image forming method using a typical electrophotographic system in such image forming apparatuses comprises a charging process in which the surface of a latent image bearing member is uniformly charged, an exposure process in which the surface is exposed imagewise and charges in the exposed zones are removed to form an electric latent image (electrostatic image), a development process in which a fine toner particle bearing an electric charge is caused to adhere to the latent image to visualize it, a transfer process in which the obtained visible image is transferred onto a transfer material such as paper, and a fixing process in which the visible image is fixed on the transfer body by heating or pressing (usually a thermal roller is used).
Two-component developers comprising a carrier and a toner and one-component developers (magnetic toners, non-magnetic toners) containing only a toner and requiring no carrier are known as the developers for developing electrostatic images formed on the latent image bearing member.
Toners used in such image forming methods comprise a binder resin and a coloring agent as the main components and, if necessary, also contain additives such as charge control agents, offset-preventing agents, and the like. The toners are required to have various properties in the above-mentioned processes. For example, in the development process, the toner and the binder resin for the toner are required to retain the amount of electric charge suited to image forming apparatuses such as copiers, printers, without being affected by ambient conditions such as temperature, humidity, and the like Furthermore, in the fixing process employing a thermal roller fixing system, the toner is required to have good anti-offset performance, that is, show no adhesion to the thermal roll, and good fixability to paper and the like. Moreover, the toner is also required to have blocking resistance properties and show no blocking during storage inside the image forming apparatuses.
In copiers, printers, facsimile machines employing an image forming method such as electrophotography, electrostatic recording, electrostatic printing, and the like, the toner is usually fixed to paper by using a heated roller which is heated to a temperature of about 100~230° C. In such a fixing process, fixing is most often continuously conducted on a large number of paper sheets and a toner is accumulated on the heated roller in a very small amount insufficient to affect the anti-offset performance. Because of continuous rotation and continuous supply of paper, the temperature of the heated roller increases and the toner that accumulated on the heated roller is heated. As a result, the residual monomers or residual solvent remaining in the toner are evaporated, producing offensive odor.
This offensive odor is caused by starting materials present in the toner, such as binder resins, pigments, charge control agents, additives, master batch pigments in which a resin is mixed with a pigment, and the like, or by residual monomers, low-molecular-weight components, volatile components such as residual solvents, components soluble in polar solvents or polar-solvent-soluble material, various components soluble in polar solvents which are produced during toner manufacture, and the like. Therefore, it is necessary to decrease the amount of residual monomers, residual solvents, volatile components, and components soluble in polar solvents, which are present in the starting materials, toner, and developer.
With respect to those requirements, for example, in Japanese Patent Application Laid-open No. H10-10782, the evaluation was conducted by a hardly objective method of deciding as to whether the offensive odor was felt or not, or the amount of volatile components was determined by the difference in weight before and after drying and could not be fully distinguished from the amount of water-containing components. Furthermore, in Japanese Patent Application Laid-open No H11-249334, the amount of residual monomers remaining in the toner was specified, but sufficient attention was not paid to the method for detecting the monomer components, the amount of monomer components detected by usual gas chromatography was specified, and the amount of components soluble in polar solvents, which presently pose a problem, was not filly taken into account. Japanese Patent Application Laid-open No H10-10782 is merely a description of a special suspension polymerized toner and only describes in detail a method for the manufacture thereof, providing no general description. Moreover, the object is the amount of volatile components, rather than the components soluble in polar solvents representing the present object. Japanese Patent Application Laid-open No. H11-249334 is described hereinbelow. However, it contained no general description, and the effect of the present object could not be fully demonstrated. Furthermore, all of the monomer components were controlled, rather than components soluble in polar solvents of the present object. The components soluble in polar solvents also contain dimer and trimer components other than monomers, and the amount of polar solvent insolubles such as non-polar solvents, e.g., hexane and the like, in the monomers is large. Japanese Patent Application Laid-open No. H11-249334 teaches, for example, the residual monomer can be removed by restricting the amount of residual monomer by means of temperature control or by conducting distillation after polymerization, or by using a method of adding an initiator during toner manufacture by a direct polymerization method or in the manufacture of binder resin Furthermore, when the toner is manufactured by grinding, the monomers can be removed by reducing pressure during heating and kneading of starting material with a kneader, or the residual monomers can be removed with a comparatively good efficiency by using spray drying in the manufacture of the toner. In particular, when the toner is manufactured by a suspension polymerization method, the removal can be conducted even when the toner particles are heated and dried,
Furthermore, the requirement relating to the decrease in the content of residual solvents, volatile components, and components soluble in polar solvents is important not only in terms of environmental protection, that is, from the standpoint of ecology, and human safety (carcinogenic and toxic substances), but also in terms of resolving the problem of toner quality. For example, recent research conducted by the inventors clearly showed that the components soluble in polar solvents which are present in the toner caused carrier spent, decreased the amount of electric charge of the toner, and were one of the reasons for decreased image density
On the other hand, because of properties required for binder resins for toners, that is, transparency, insulating properties, water resistance, flowability (as a powder), mechanical strength, gloss, thermoplasticity, grindability, and the like, polystyrene styrene—acryl copolymers, polyester resins, and epoxy resins have been usually used as the binder resins. Among them, styrene resins have been widely used because of their excellent grindability, water resistance, and flowability.
The following problem, however, was associated with toners containing styrene resins and toners containing polyester resins. Thus, when copies obtained by using such toners, were stored in document holders made of vinyl chloride resin sheets, because the image surface on the copies was allowed to be in a state of intimate contact with the vinyl chloride resin sheets, a plasticizer contained in the sheet
Asahina Yasuo
Masuda Minoru
Mochizuki Satoshi
Sugiura Hideki
Suzuki Kohsuke
Dote Janis L.
Ricoh & Company, Ltd.
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