JP2004029603A - Full-color image forming apparatus using polymerizing-method toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control toner layers on the developing rollers of respective colors to a target thickness in a full-color image forming apparatus using a polymerizing-method toner. <P>SOLUTION: The full-color image forming apparatus is equipped with a plurality of developing devices each equipped with a toner manufactured by a polymerizing method, a developing roller provided where it comes into contact with an electrostatic latent image carrier, and a restricting member restricting a toner on the developing roller into a thin layer; and developing rolls are different in surface roughness (Ra) by the developing devices of the respective colors and the developing rolls have their metal roll surfaces processed by blasting. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus which includes a plurality of developing devices for developing an electrostatic latent image on an electrostatic latent image carrier with a polymerization toner and forms a full-color image.
[0002]
[Prior art]
At present, most toners used in electrophotographic printers and copiers are manufactured by a so-called pulverizing method. However, the toner obtained by the pulverization method is approaching its limit in providing functions such as finer particle diameter, low-temperature fixability, and durability during high-speed printing.
[0003]
On the other hand, polymerization toners that can freely control the particle size and achieve both durability and low-temperature fixability have been spotlighted.
[0004]
[Problems to be solved by the invention]
However, since the polymerized toner has a shape close to a sphere, it is difficult to regulate the toner with a blade, and the chargeability and fluidity of the toner are high and the cohesiveness of the toner particles is low. It is very difficult to control the thickness of the toner layer to a desired thickness.In particular, in a full-color image forming apparatus using a plurality of developing devices, each of which develops an image of a different color, if the thickness of the toner layer changes, the purpose and Because of the inability to express the desired hue, polymerization toners are limited to image forming apparatuses for monochrome printing.
[0005]
The present invention relates to a full-color image forming apparatus using a polymerized toner and using a plurality of developing devices each containing a toner of a different color, and controlling a toner layer on each developing roller to a target thickness. The purpose is to do.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a toner produced by a polymerization method, a developing roller provided at a position in contact with an electrostatic latent image carrier, and a regulating member for regulating the toner on the developing roller to a thin layer are provided. In an image forming apparatus in which a plurality of developing devices are arranged, a plurality of developing devices having different surface roughness of a developing roll are used.
[0007]
Further, the toner is manufactured by using the emulsion polymerization method, and the circularity of the toner is reduced, so that the effect of regulating the toner amount by the regulating blade is improved.
[0008]
The material of the developing roll is made of metal, and the surface is easily blasted to have a predetermined surface roughness.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view of the full-color electrophotographic apparatus of the present embodiment. This electrophotographic apparatus is filled with a photosensitive member (photosensitive belt 102) serving as a latent image holding means and polymerized toners of four different colors of yellow, magenta, cyan and black on the right side of the photosensitive belt 102 in FIG. Developing devices 1Y, 1M, 1C and 1K are arranged, an exposing device 104 for forming a latent image on the photosensitive belt 102 is arranged below the developing device 1C, and a charging device is arranged below the photosensitive belt 102. 105 is arranged. Below the exposure device 104, a paper feed cassette 106 for storing cut paper as a recording medium is arranged. An intermediate transfer member (transfer drum 107) is disposed on the left side of the photosensitive belt 102 in FIG. 1, and a fixing device 101 is disposed above the intermediate transfer member. Further, each of the developing devices 1Y, 1M, 1C, and 1K has an identification shape portion (not shown).
[0010]
The photosensitive belt 102 serving as a latent image holding unit is driven in a direction indicated by an arrow 102a. The photosensitive layer on the surface of the driven photosensitive belt is uniformly charged by the charging device 105. Next, an image and character information from a personal computer, an image scanner, or the like are exposed in dot units by the exposure device 104 to form an electrostatic latent image on the photosensitive belt 102. The electrostatic latent image formed on the photosensitive belt 102 is developed into a toner image of a corresponding color by one of the developing devices 1Y, 1M, 1C, and 1K. The toner image formed on the photosensitive belt 102 is transferred onto the transfer drum 107 rotating in the direction of the arrow 107a.
[0011]
The above-described cycle is sequentially performed on the developing devices 1Y, 1M, 1C, and 1K, so that a color toner image in which four color toners are superimposed is formed on the transfer drum 107. At the same time, a recording medium such as a sheet and an OHP is sent from the paper supply cassette 106 at a proper timing, so that the toner image is transferred onto the recording medium. The recording medium onto which the toner image has been transferred passes through the fixing device 101 and is heated and pressed, so that the toner melts and is fixed on the recording medium, and is discharged to the upper portion of the electrophotographic apparatus.
[0012]
Next, the developing device of the full-color electrophotographic apparatus of this embodiment will be described in detail. FIG. 2 is a schematic diagram of the developing devices 1Y, 1M, 1C, and 1K. The toner storage chamber 1 stores a polymerization toner 2 used for development. Conveying blades 3 are arranged in the toner storage chamber 1, and are configured to convey the polymerization toner 2 to the developing roll 5 side by their rotation. A supply roll 4 made of a conductive elastic foam roll is disposed at the front of the toner storage chamber 1, and supplies the polymerization toner 2 transported to the front of the toner storage chamber 1 to the development roll 5. The polymerized toner 2 supplied onto the developing roll 5 is regulated by the regulating blade 6 to a toner layer thickness appropriate for development, and the polymerized toner is frictionally charged by rubbing with the regulating blade 6.
[0013]
In the present embodiment, the developing roll 5 is made of metal, and is subjected to blasting with glass beads to have a predetermined surface roughness. In particular, when the developing roll 5 is made of an aluminum material, it is preferable because processing is easy. The aluminum material developing roll 5 can be easily formed to have a predetermined surface roughness by adjusting the pressure at which the glass beads are blown.
[0014]
Next, the polymerization toner 2 used in the examples will be described. Any known method can be used for the production of the polymerization toner. For example, the production of the polymerization toner includes a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, and an interfacial polymerization method.
[0015]
The production of a toner by a conventional pulverization method includes six steps of a resin polymerization step, a raw material mixing step, a melt kneading step, a pulverization step, a classification step, and an external addition step. A first step in which a monomer mixture is added to a dispersion in which wax fine particles are present to perform seed emulsion polymerization, and the obtained polymer dispersion and a colorant dispersion are mixed, and the particles of the dispersion are aggregated and heated. Thus, the production is performed in three steps: a second step of preparing aggregated particles, and a third step of washing and drying the obtained aggregated particles and performing an external addition treatment of fine particles. In the production of the polymerization method toner used in this example, the number of steps can be significantly reduced, and particularly, since the melting and kneading step and the pulverizing step which consume a large amount of production energy can be reduced, the production energy and the production cost can be greatly reduced. .
[0016]
Further, in the polymerization method toner used in the present example, low-melting wax was used and emulsion polymerization was performed in the presence of the wax particles, thereby producing a toner having both low-temperature fixability and durability. As the wax, any one of known waxes having a low melting point can be used. Specific examples of such a wax include olefin-based waxes such as low molecular weight polyethylene, low molecular weight polypropylene, copolymerized polyethylene, grafted polyethylene, and grafted polypropylene; behenyl behenate, montanic acid ester, stearyl stearate, and the like. Ester wax having long-chain aliphatic group, vegetable wax such as hydrogenated castor oil, carnauba wax, ketone having long-chain alkyl group such as distearyl ketone, silicone wax having alkyl group and phenyl group, stearic acid, etc. Fatty acids, higher fatty acid amides such as oleic acid amide, stearic acid amide, etc., long chain fatty acid alcohols, long chain fatty acid polyhydric alcohols such as pentaerythritol, and partial esters thereof, paraffin wax, Fischer-Tropsch Box, etc. are exemplified.
[0017]
Among these waxes, those having a melting point of 100 ° C. or less are more preferable for improving the fixing property, the melting point of the wax is more preferably in the range of 40 to 90 ° C., and the melting point of the wax is particularly preferably 50 to 80 ° C. Range. When the melting point exceeds 100 ° C., the effect of lowering the fixing temperature becomes poor.
[0018]
The shape of the polymerization toner used in this embodiment can be controlled in a wide range from an irregular shape to a spherical shape by controlling the conditions of the aggregation / heating step. FIG. 3 shows the measurement results of the amount of toner adhering to the developing roll with respect to the circularity of the projected image of the polymerization toner when the developing device shown in FIG. 2 is used. In addition, the flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation was used for measuring the degree of circularity of the projected image. From FIG. 3, the projected image circularity of the polymerization method toner and the amount of adhesion on the developing roll correspond almost one-to-one, and the regulation is made as the degree of the projection image circularity of the polymerization toner approaches 1, ie, as the shape approaches a sphere. It can be seen that the toner regulating effect of the blade is reduced. From the results shown in FIG. 3, when the target value of the amount of the polymerized toner adhered on the developing roll is 0.45 mg / cm ² , the circularity of the projected image of the polymerized toner is preferably in the range of 0.94 to 0.98. More preferably, it is in the range of 0.95 to 0.97, and in this range, the control of the thickness of the toner layer becomes easy.
[0019]
FIG. 4 shows, using the developing device shown in FIG. 2, the average roughness of the developing roll surface of the polymerization toner of each color of yellow (Y), magenta (M), cyan (C), and black (K). It is the result of measuring the amount of toner adhering on the developing roll. The developing roll surface roughness (Ra) was measured along the axial direction of the developing roll. It is sufficient that the development roll surface roughness (Ra) is in the range of 0.2 to 0.5 μm. From FIG. 4, it can be seen that the amount of toner of each color polymerization method corresponds to the surface roughness of the developing roll almost one-to-one. When looking at FIG. 4 in detail, a difference in the amount of adhesion between each color of yellow (Y), magenta (M), cyan (C), and black (K) is seen. For these reasons, even if a developing roll having the same surface roughness is used, the amount of adhesion will not be the same depending on the color, so setting the developing roll surface roughness for each color of the polymerization method will provide a more accurate full-color image. Can be reproduced. From the results in FIG. 4, when the target value of the amount of the polymerized toner adhered on the developing roll is a hatched portion in FIG. 4 centering on 0.45 mg / cm ² , the surface roughness of the developing roll used in the developing device of each color (Ra) is 0.35 to 0.42 μm for yellow (Y), 0.27 to 0.38 μm for magenta (M), 0.35 to 0.46 μm for cyan (C), and 0.1 to 0.46 μm for black (K). 29 to 0.41 μm.
[0020]
【The invention's effect】
As described above, in the image forming apparatus according to the present invention, by using the polymerized toner manufactured by the emulsion polymerization method, by adjusting the circularity of the projected image of the polymerized toner and the surface roughness of the developing roll, Further, it is possible to provide a full-color image forming apparatus capable of making the amount of toner adhered on the developing roll uniform for each color and accurately reproducing the hue.
[Brief description of the drawings]
FIG. 1 is a schematic side view of an electrophotographic apparatus according to an embodiment.
FIG. 2 is a schematic side view of a developing device of the electrophotographic apparatus according to the embodiment.
FIG. 3 is a diagram illustrating the relationship between the amount of toner adhered on a developing roller and the toner shape of a polymerization method toner used in the electrophotographic apparatus of the embodiment.
FIG. 4 is an explanatory diagram showing the relationship between the amount of toner adhered on a developing roller of a polymerization method toner used in the electrophotographic apparatus of the embodiment and the surface roughness of a developing roll.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Toner storage room, 2 ... Polymerization toner, 3 ... Conveying blade, 4 ... Supply roll, 5 ... Development roll, 6 ... Regulation blade, 101 ... Fixing device, 102 ... Photosensitive belt, 104 ... Exposure device, 105 ... Charging Apparatus, 106: paper cassette, 107: transfer drum.

Claims (5)

A developing device provided with a toner manufactured by a polymerization method, a developing roller provided at a position in contact with the electrostatic latent image carrier, and a regulating member for regulating the toner on the developing roller to a thin layer, In a full-color image forming apparatus having magenta, cyan, and black colors,
A full-color image forming apparatus, wherein the plurality of developing devices include developing devices having different surface roughnesses (Ra) of developing rolls. 2. The full-color image forming apparatus according to claim 1, wherein the toner is a toner manufactured by an emulsion polymerization method. 2. The full-color image forming apparatus according to claim 1, wherein the circularity of the toner particle projected image is 0.94 to 0.98. The surface roughness (Ra) of the developing roller of the developing device of each color according to claim 1,
A full-color image forming apparatus having a thickness of 0.2 to 0.5 μm. 2. The full-color image forming apparatus according to claim 1, wherein the developing roller is formed by blast processing on a metal roll.

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