Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1999-10-04
2001-01-09
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S111400, C430S137170
Reexamination Certificate
active
06171743
ABSTRACT:
This application is based on Japanese Patent Application No. Hei 10-282330 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrostatic latent image-developing toner.
2. Description of the Related Art
An emulsified dispersion method has been conventionally known as one of methods for producing resin particles. In such a method, a resin solution obtained by dissolving a resin in a non-aqueous organic solvent is emulsifiedly dispersed in an aqueous medium to form an emulsion, and the emulsion is heated under continuous stirring to remove the organic solvent by allowing it to evaporate, whereby resin particles are obtained. According to the emulsified dispersion method, polymer fine particles having a mean particle size of about 1 to 10 &mgr;m can be obtained with a comparatively easy operation simplifying a process, so that the emulsified dispersion method can improve a production efficiency and, at the same time, cost reduction as compared to a pulverization method and a suspension polymerization method. Further, the number of kind of resin usable in the emulsified dispersion method is more than that in the suspension polymerization method and the like.
Accordingly, it is expected that, if such a emulsified dispersion method is put into practical use to blend toner components, such as a colorant, a charge control agent and a magnetic powder, into the resin solution, an electrostatic latent image-developing toner answering needs with respect to fields of a coping machine and a printer in an electrophotograghic system, such as high speed, high picture quality and coloration, can be comparatively easily obtained at a low price. For example, Japanese Patent Application Laid-Open Nos. 91,666/1986 and 25,664/1988 disclose a manufacturing method for an electrostatic latent image-developing toner, in which the emulsified dispersion method is applied.
However, the toner obtained by the emulsified dispersion method has many air caves inside, because water is easily taken into an oily droplet in O/W type emulsion at a step for emulsifiedly dispersing. Therefore, there is the problem that a chargeability changes easily due to a change of surrounding environments and imaging properties tend to be adversely affected.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrostatic latent image-developing toner which can maintain a good charge stability and good imaging properties for a long time even when surrounding environments change.
The object of the present invention can be achieved by an electrostatic latent image-developing toner produced by means of a wet granulation method, containing at least a binder resin and a colorant, and having a volume-area mean particle size (D) of 1 to 10 &mgr;m, a shape coefficient (S) of 103 to 130, and a constant (A) of 0.25 to 2, in which;
the volume-area mean particle size (D) is defined by the below equation (1):
D
=
∑
(
ni
×
(
Di
)
3
)
∑
(
ni
×
(
Di
)
2
)
(
1
)
wherein “ni” and “Di” respectively denote “the number of particle” and “particle size (representative diameter)” of each particle size division in the distribution of number-standard particle size;
the shape coefficient (S) is defined by the below equation (2):
S
=
(
perimeter
)
2
area
×
1
4
π
×
100
(
2
)
wherein “perimeter” and “area” respectively denote perimeter (peripheral length) and area of the projected image of toner particle;
the constant (A) is defined by the below equation (3):
A
=
S
B
S
W
-
1
(
3
)
wherein “SB” denotes a BET specific surface and “SW” is defined by the below equation:
S
W
=
6
×
S
ρ
×
D
×
100
wherein “&rgr;” denotes a specific gravity of toner, “D” and “S” respectively denote the above-mentioned volume-area mean particle size (D) and shape coefficient (S).
DETAILED DESCRIPTION OF THE INVENTION
The electrostatic latent image-developing toner of the present invention contains at least a binder resin and a colorant and has a volume-area mean particle size (D) of 1 to 10 &mgr;m, a shape coefficient (S) of 103 to 130, and a constant (A) of 0.25 to 2.
When a toner has many air caves inside, the moisture in the air is easily taken into toner by the capillarity of the air caves connected to toner surface and the minute unevenness on toner surface, so that a chargeability changes due to a change of the surrounding environments and imaging properties are adversely affected. The electrostatic latent image-developing toner of the present invention can maintain a stable chargeability and good imaging properties even when a change of the surrounding environments occures, by optimizing a volume-area mean particle size (D), a shape coefficient (S), and a constant (A) defined in the above equations (1) to (3).
The volume-area mean particle size (D) is defined by the below equation (1):
D
=
∑
(
ni
×
(
Di
)
3
)
∑
(
ni
×
(
Di
)
2
)
(
1
)
wherein “ni” and “Di” respectively denote “the number of particle” and “particle size (representative diameter)” of each particle size division in the distribution of number-standard particle size, means a ratio of the sum total of volume of particles measured in number-standard to the sum total of area of those, and is also called a specific surface particle size.
The volume-area mean particle size (D) can be measured by Coulter Multisizer (made by Coulter Counter K.K.). However, the volume-area mean particle size (D) does not need to be necessarily measured by the above-mentioned apparatus, and any apparatus may be used as long as it is capable of carrying out measurement and calculation of mean particle size based on the above-mentioned equation (1).
The shape coefficient (S) is defined by the below equation (2):
S
=
(
perimeter
)
2
area
×
1
4
π
×
100
(
2
)
wherein “perimeter” and “area” respectively denote perimeter (peripheral length) and area of the projected image of toner particle. In the present invention, the “S” value is calculated as a mean value of two hundreds of toner particles. The shape coefficient (S) is an index showing a overall shape of toner particle and means that the closer the value to 100, the closer the toner particle shape in the projected image to true sphericity.
In the present description, as for the perimeter and area of the projected image of toner particle, the value measured by means of SEM image of toner particles (magnification of 1,000 to 5,000) from LUZEX 5000 (made by Nihon Regulator K.K.) is used. However, a measuring apparatus for photography and the apparatus for measurement are not especially limited to the above apparatus as long as they are respectively capable of taking a photograph of toner particles and measuring the perimeter and area of toner particles.
The constant (A) is defined by the below equation (3):
A
=
S
B
S
W
-
1
(
3
)
wherein “SB” denotes a BET specific surface and “SW” is defined by the below equation:
S
W
=
6
×
S
ρ
×
D
×
100
wherein “&rgr;” denotes a specific gravity of toner, “D” and “S” respectively denote the above-mentioned volume-area mean particle size (D) and shape coefficient (S).
The constant (A) is an index showing surface properties of toner particles and means that the closer the value is to 0, the fewer the air caves are that are connected to the toner surface and the minute unevenness on toner surface so that toner particles have smooth surface. Thus, the constant (A) is prescribed by a ratio of “SB” to “SW” so that the surface properties of the toner particles are precisely reflected by the constant (A).
In the present description, the toner specific gravity (&rgr;) and the BET specific surface (SB) are respectively measured by Air Comparison Pyonometer Model 930 (made by BECKMAN K.K.) and Flow Sorb 2300 (made by Shimazu Seisakusyo K.K.) . However, a measuring apparatus is not especially limited to t
Burns Doane , Swecker, Mathis LLP
Goodrow John
Minolta Co. , Ltd.
LandOfFree
Electrostatic latent image-developing toner does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrostatic latent image-developing toner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrostatic latent image-developing toner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2462758