Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-09-26
2002-03-05
Chapman, Mark (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S108400
Reexamination Certificate
active
06352808
ABSTRACT:
This application is based on application No. 278957/1999 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrostatic-latent-image developing toner used for electrophotography, electrostatic printing, etc. and inorganic particles used for such a toner.
2. Description of the Related Art
It has been widely known that in an attempt to impart a desired fluidity to a toner used for electrophotography, electrostatic printing, etc., inorganic particles, such as silica and titania, are externally added to the toner. In particular, along with the recent demands for digitized and high-quality images, there have been ever-increasing demands for small-size toners. In order to impart a desired fluidity to such a small-size toner, a large amount of fluidizer is required. In the case of full-color toners in which the above-mentioned requirements are demanded most strictly, not less than 1% of inorganic particles having a ultra-fine particle size with an average primary particle size in the range of approximately 10 to 50 nm are externally added to and mixed with the toner.
However, when such a large amount of inorganic particles having a ultra-fine particle size are externally added to the toner, inorganic particles separated from the toner tend to pass through the gap between the photosensitive member and the cleaning blade and to be anchored on the photosensitive member, resulting in BS (black spots) on a copied image. When the anchoring of the inorganic particles occurs on the photosensitive member, the toner accumulates in the vicinity thereof, causing BS to appear as noise in a non-image portion on a copied image.
In order to solve such a problem, a technique has been proposed (Japanese Patent Application laid-open Hei 2-89064) in which hard inorganic particles are externally added to a toner so as to remove the anchored matter on the surface of the photosensitive member through sanding. However, although this technique reduces the occurrence of BS, it makes the surface of the photosensitive member and the cleaning blade susceptible to abrasion, resulting in a reduction of life of these members.
From the viewpoint of prevention of the anchoring on the surface of the photosensitive member, another technique for externally adding fatty-acid metal salt particles to a toner (Japanese Patent Application laid-open Sho. 60-198556) has been proposed. However, in such a technique, since the particle size of the fatty-acid metal salt particles is not less than 3 &mgr;m. This size is rather large. A considerable amount of addition is required in order to efficiently obtain the effect. However, the considerable amount of addition results in degradation in the toner chargeability and the subsequent fog on a copied image.
U.S. Pat. No. 5,378,572 discloses a technique in which an inorganic compound, subjected to a surface treatment by a treatment agent such as a fatty-acid metal salt, is externally added to a toner. In this reference, either a first fatty-acid metal salt or a second fatty-acid metal salt is used as the fatty-acid metal salt. When carrying out the surface treatment, a dispersion solution containing the fatty-acid metal salt dispersed therein is used and to this is added the inorganic compound and stirred. However, such a technique has a difficulty in exerting the BS-reducing effect, and also produces aggregated matters of the inorganic particles that have been surface-treated, resulting in scratches on the surface of the photosensitive member and the subsequent image noise. Similar techniques have been proposed in, for example, U.S. Pat. No. 5,604,071, Japanese Patent Application Laid-Open Hei 5-66607, EP No. 0 744 668 and U.S. Pat. No. 5,837,413; however, any of these techniques have problems of BS and image noise.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrostatic-latent-image developing toner which can reduce the anchoring and scratches on the photosensitive member and which is superior in the chargeability, and is also to provide inorganic particles used for such a toner.
Another objective of the present invention is to provide an electrostatic-latent-image developing toner which can reduce the anchoring, scratches and wearing on the photosensitive member and which is superior in the chargeability and cleaning properties, and is also to provide inorganic particles used for such a toner.
The present invention relates to a toner comprising:
toner particles containing a binding resin and a colorant;
an externally additive agent externally added to the toner particle, the additive agent being inorganic particles which have an alkali metal salt of a fatty acid (hereinafter, referred to as a first fatty-acid metal salt) and a non-alkali metal salt of a fatty acid (hereinafter, referred to as a second fatty-acid metal salt) on the surface thereof, the first fatty-acid metal salt having a metal that is an alkaline metal, the second fatty-acid metal salt having a metal that is other than an alkali metal,
a ratio of the first fatty-acid metal salt to the second fatty-acid metal salt being set in the range of 0.01 to 0.5% by weight.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides an electrostatic-latent-image developing toner comprising:
toner particles containing a binding resin and a colorant;
an externally additive agent externally added to the toner particle, the additive agent being inorganic particles which have a first fatty-acid metal salt and a second fatty-acid metal salt on the surface thereof, the first fatty-acid metal salt having a metal that is an alkaline metal, the second fatty-acid metal salt having a metal that is other than an alkali metal,
a ratio of the first fatty-acid metal salt to the second fatty-acid metal salt being set in the range of 0.01 to 0.5% by weight.
The present invention also provides an additive agent for toner, comprising:
inorganic particles;
a first fatty-acid metal salt existing on the surface of the inorganic particles, the first fatty acid metal salt having a metal that is an alkali metal; and
a second fatty-acid metal salt existing on the surface of the inorganic particles, the second fatty-acid metal salt having a metal other than an alkali metal,
a ratio of the first fatty-acid metal salt to the second fatty-acid metal salt being set in a range of 0.01 to 0.5% by weight.
The additive agent for toner is characterized in that a fatty-acid alkali metal salt is added to an aqueous system containing inorganic particles in the presence of metal ions other than alkali metal ions (referred to as “non-alkali metal ions” hereinafter) so as to allow a fatty-acid non-alkali metal salt to deposit on the surface of inorganic particles.
The toner of the present invention is formed by externally adding specific inorganic particles (additive agent for toner) to toner particles. The expression, “externally added”, refers to the fact that the inorganic particles are added to the preliminarily prepared toner particles so as to allow them to exist on the surface (peripheral portion) of the toner particles.
In the present invention, each of the inorganic particles externally added to the toner particles is provided with at least a first fatty-acid metal salt and a second fatty-acid metal salt on the surface thereof. In other words, the surface of the externally added inorganic particles of the present invention is coated with at least a first fatty-acid metal salt and a second fatty-acid metal salt, and more preferably, the surface thereof is coated uniformly with at least a first fatty-acid metal salt and a second fatty-acid metal salt.
A ratio of the first fatty-acid metal salt to the second fatty-acid metal salt on the surface of inorganic fine particles is set in the range of 0.01 to 0.5% by weight, preferably in the range of 0.01 to 0.2% by weight. The ratio exceeding 0.5% by weight is not preferable since it causes an extreme reduction in the chargeability when the inorganic particle
Aoki Megumi
Arai Takeshi
Hagi Masayuki
Kido Kenichi
Mikuriya Yoshihiro
Burns Doane , Swecker, Mathis LLP
Chapman Mark
Minolta Co. , Ltd.
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