JP2003280311A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a low temperature offset of toner in color image formation obtained by superposing and thermally fixing the toner having a plurality of colors. <P>SOLUTION: In heat fixing, the toner having four colors of yellow, magenta, cyan and black is superposed and transferred sequentially on a transfer material 6, and the yellow (Y) toner 13Y is toner facing the fixing surface of a heating roller 8a. The black (BK) toner 13BK directly adheres to the transfer material 6, and does not face the fixing surface. The external additive isolation rate of the yellow toner 13Y being the toner facing the fixing surface is smaller than the external additive isolation rates of the toner 13M, 13C and 13BK of other colors, and is set to the minimum. Thereby, the isolated external additive of the toner 13Y existing between the toner 13Y and the fixing surface decreases, which prevents the low temperature offset. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image for forming a color image by transferring toners of a plurality of colors (two or more colors) such as yellow, magenta, cyan, and black onto a transfer material such as paper in an overlapping manner. The present invention belongs to the technical field of a forming apparatus, and more particularly to the technical field of a color image forming apparatus that heats and fixes toners of a plurality of colors that are superposed on a transfer material.

[0002]

2. Description of the Related Art Conventionally, in a full-color image forming apparatus, four color toners of, for example, yellow, magenta, cyan, and black are sequentially superposed and transferred onto a transfer material such as paper, and the superposed four color toners are also transferred. A full-color image is formed by heating and fixing.

Conventionally, in order to improve the characteristics of the toner such as fluidity or chargeability, such as the toner used in such a full color image forming apparatus, the toner used in the image formation is generally this toner. External additives according to the purpose of improving the characteristics are attached to the mother particles.

In this case, in order to improve the toner characteristics more effectively, it is possible to improve the toner characteristics such as chargeability by defining the coverage of the external additive on the mother particles. It has been proposed in the publication. In the external addition of the external additive to the mother particles, which is disclosed in this publication, the coverage of the external additive to the mother particles, the average particle size of the mother particles and the external additive, the mother particles and the external additive, From each specific gravity of, and the addition amount of the external additive to the mother particles,
It is calculated by a predetermined formula on the assumption that all the added external additives cover the mother particles.

In addition, the process of developing an electrostatic latent image with one color toner and transferring it to the transfer material is repeated and sequentially transferred to the transfer material for four color toners of cyan, yellow, magenta and black. In the method for obtaining a full-color image, the amount of the fluidizing agent that is an external additive contained in the toner of each color is increased as the toner of the color that contributes to the development later improves the toner characteristics, JP-A-6-324525 proposes to obtain a clear full-color image without transfer failure.

[0006]

By the way, in an image forming apparatus, a toner image on which an electrostatic latent image has been developed is transferred onto a transfer material such as paper and then generally heat-fixed to form an image on the transfer material. Is formed. In that case, in a color image forming apparatus such as a full-color image forming apparatus in which toners of a plurality of colors are superposed and transferred onto a transfer material and then heated and fixed, the toners of the respective colors are formed from relatively insoluble mother particles containing a THF insoluble component. When formed and when the fixing temperature is relatively low, the mother particles do not melt during heat fixing and peel off from the transfer material, and a part of the peeled toner adheres to the fixing surface of the fixing member. There is a problem that low temperature offset occurs.

Therefore, as disclosed in both of the above-mentioned publications, it is possible to prevent the occurrence of the low temperature offset by improving the toner fixing characteristics by improving the toner characteristics.

First, considering the improvement of the toner fixing characteristics by the improvement of the toner characteristics disclosed in the above-mentioned Japanese Patent Laid-Open No. 2001-66821, the improvement of the toner characteristics disclosed in this publication is premised on addition. All of the external additives described above cover the mother particles. However, in reality, the added external additives do not all adhere to the mother particles, and the free external additives released from the mother particles are often mixed in the toner. Therefore, the external additive coverage disclosed in this publication cannot be said to properly represent the state of attachment of the external additive to the mother particles. Therefore, even if the improvement of the toner characteristics disclosed in this publication is simply applied to a color image forming apparatus in which toners of a plurality of colors are transferred onto a transfer material in a superimposed manner and then heat-fixed, the occurrence of a low temperature offset is effectively generated. It is difficult to prevent.

Considering the improvement of the toner fixing characteristics by the improvement of the toner characteristics disclosed in the above-mentioned Japanese Patent Laid-Open No. 6-324525, the improvement of the toner characteristics disclosed in this publication discloses that the toner of each color is The amount of the external additive contained in the toner is simply increased as the toner of the color that contributes to the development later. However, as described above, in many cases, free external additives are actually mixed in the toner. Therefore, as disclosed in this publication, toner of a color that contributes later to development is more likely to contain external additives. It cannot be said that the attachment state of the external additive to the mother particles is appropriate simply by increasing the addition amount. Therefore, even if the improvement of the toner characteristics disclosed in this publication is simply applied to a color image forming apparatus in which toners of a plurality of colors are transferred onto a transfer material in a superimposed manner and then heat-fixed, the occurrence of a low temperature offset is effectively generated. It is difficult to prevent.

Further, in a color image forming apparatus in which toners of a plurality of colors are superposed and transferred on a transfer material and then heated and fixed,
It is desired that the charging characteristics of the toners of a plurality of colors are made as uniform as possible and the developing conditions are made as close as possible to each other. However, in the improvement of the toner characteristics disclosed in both of the above-mentioned Japanese Patent Laid-Open Nos. Since the adhered state of the agent is not properly taken into consideration, there is also a problem in that it is difficult to make the respective charging characteristics of the toners of a plurality of colors as uniform as possible.

The present invention has been made in view of the above circumstances, and an object thereof is to effectively prevent low-temperature offset of toner in color image formation in which toners of a plurality of colors are superposed and heat-fixed. It is an object of the present invention to provide a color image forming apparatus that can effectively obtain good fixing characteristics.

Another object of the present invention is to provide a color image forming apparatus which can make developing conditions as uniform as possible by making the charging characteristics of toners of a plurality of colors more effectively and uniformly.

[0013]

In order to solve this problem, a color image forming apparatus according to the invention of claim 1 is provided with a large number of mother particles each containing a THF insoluble component, and these mother particles are respectively attached to these mother particles. In a color image forming apparatus for forming a color image by superposing a plurality of color toners including at least black, which are composed of a large number of particles of an external additive, on a transfer material, and heating and fixing these toners by a fixing member, At the time of heat fixing, among the toners of the plurality of colors adhered to the transfer material, the toner facing the fixing surface of the color closest to the fixing surface of the fixing member is at least a color other than black, and the fixing surface The external additive release rate of the free external additive released from the mother particles of the fixing surface opposite toner is smaller than the external additive release rate of the toner of other colors. It is characterized in that it is a constant.

Further, the invention of claim 2 is characterized in that the external additive release rate of the toner of the plurality of colors is the external additive release rate of the toner supplied to the corresponding developing device. .

Further, in the invention of claim 3, the toners of the plurality of colors are yellow, magenta, cyan and black toners respectively, and the fixing surface facing toner is any one of yellow, magenta and cyan toners. It is characterized by being. Furthermore, the invention of claim 4 is characterized in that the amount of the external additive adhering to the mother particles is set to be the same or substantially the same among the toners of the plurality of colors.

[0016]

According to the color image forming apparatus of the present invention having the above-described structure, the mother particles of the toner contain a THF-insoluble component which is difficult to dissolve, and the toner facing the fixing surface has at least a color other than black. Since the toner is a toner, and the external additive liberation rate of the free external additive of the fixing surface-opposed toner released from the mother particles of the fixing surface-opposed toner is set to be smaller than the external additive liberation rate of the toner of another color, The amount of the free external additive existing between the fixing surface facing toner and the fixing surface becomes relatively small. As a result, the heat from the fixing member is transferred to the base particles of the toner facing the fixing surface without being significantly hindered by the free external additive. Therefore, the temperature of the mother particles that are relatively insoluble due to the THF-insoluble component of the toner facing the fixing surface is controlled more appropriately, and the occurrence of low temperature offset is prevented.

Particularly, in the invention of claim 2, the external additive release rate of the toners of a plurality of colors is defined by the external additive release rate of the toner supplied to the corresponding developing device. As a result, the external additive release rates of the toners of a plurality of colors can be set more easily. According to the third aspect of the invention, since yellow, magenta, cyan and black toners are used as a plurality of color toners, respectively, a high quality full color image can be obtained.

Further, in the invention of claim 4, the amount of the external additive (referred to as a synchronous external additive in the toner analysis method using a PT analyzer described later) adhering to the mother particles is between the toners of plural colors. Are set to be the same or almost the same, the inclination of the synchronization straight line (approximate straight line) obtained by the toner analysis method using the PT analyzer disclosed in Japanese Patent Laid-Open No. 2000-047425 is set to be the same. .
Therefore, the charging characteristics of the toners of a plurality of colors become uniform or nearly uniform, and the developing conditions become the same or substantially the same. Therefore, it is possible to form the developing device for each color with respect to the image carrier and the shape of each developing device, and to set the developing bias to be the same. As a result, various developing methods can be flexibly and effectively adopted according to the purpose.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a full-color image forming apparatus which is an example of an embodiment of a color image forming apparatus according to the present invention.
FIG. 3 is a diagram schematically showing the intermediate transfer type color image forming apparatus.

As shown in FIG. 1, the color image forming apparatus 1 of this example is an image forming apparatus of a tandem type as a toner image forming method, and includes an exposing device 2 for forming an electrostatic latent image, a yellow (Y), Toner image forming devices 3 _Y , 3 _M , 3 _C , for each color of magenta (M), cyan (C), and black (BK)
3 _BK , an intermediate transfer member (primary transfer member) 4 including a transfer belt or a transfer drum as shown in the figure, and primary transfer devices 5 _Y , 5 for primary transfer to the intermediate transfer member 4, respectively.
_M , 5 _C , 5 _BK , a secondary transfer device 7 that secondarily transfers the primary transfer image on the intermediate transfer member 4 to a transfer material 6 such as paper by a transfer roller,
At least a fixing device 8 for fixing the secondary transfer image on the transfer material 6 with a heating roller (corresponding to the fixing member of the invention) 8a is provided. The toner image forming devices 3 _Y , 3 _M , 3 _C and 3 _BK of the respective colors are
The intermediate transfer members 4 are arranged in tandem in this order from the upstream side in the moving direction.

Toner image forming device 3 for each color_Y, 3_M, 3_C, 3_BK
Are respectively exposed by the exposure device 2.
Image carrier 9 on which a color electrostatic latent image is formed_Y, 9_M, 9_C, 9
_BKAnd these image carriers 9_Y, 9_M, 9_C, 9_BKEach obi
Charger 10 that is charged by an electric roller or the like _Y, 10_M, 10_C, 10_BK
And the toner conveyed by the developing roller, etc.
Carrier 9_Y, 9_M, 9_C, 9_BKDevelop the electrostatic latent image on the toner
Developing device 11 for forming an image_Y, 11_M, 11_C, 11_BKAnd the primary
After transfer, each image carrier 9_Y, 9_M, 9_C, 9_BKToner remaining on
Cleaning device 12 for removing_Y, 12_M, 12
_C, 12_BKIs prepared.

As shown in FIG. 2, the toner 13 used in the color image forming apparatus 1 of this example is composed of a large number of toner mother particles 14 and a large number of particles of the external additive 15 for each color. There is. In that case, the toner 13 has
Synchronous toner in which the external additive 15 is attached to the toner mother particles 14 and asynchronous toner mother particles 14 'in which the external additive 15 is not attached
And non-synchronous external additive (free external additive) particles 15 'that do not adhere to the toner mother particles 14 are mixed. It should be noted that the external additive 15 attached to the toner mother particles 14 is indicated by the symbol "1" in FIG.
5 ″ ”.

In the color image forming apparatus 1 of this example configured as described above, first, the toner image forming apparatuses 3 _Y and 3 _{Y of} the respective colors are formed.
_{In M} , 3 _C and 3 _BK , after the image carriers 9 _Y , 9 _M , 9 _C and 9 _BK are charged by the chargers 10 _Y , 10 _M , 10 _C and 10 _BK , respectively, the exposure device 2 is used. Each image carrier 9 _Y , 9 _M , 9 _C , 9 _BK
Are exposed for each color, and each image carrier 9 _Y , 9 _M , 9 is exposed.
Electrostatic latent images of colors corresponding to _C and 9 _BK are formed.

Next, the electrostatic latent images on the image carriers 9 _Y , 9 _M , 9 _C and 9 _BK are respectively transferred to the developing devices 11 _Y , 11 _M , 11 _C and 1 respectively.
The toner of each color conveyed by the developing roller of 1 _BK is developed, and the toner image of each color is formed on each image carrier 9 _Y , 9 _M , 9 _C , 9 _BK . These toner images are _primarily transferred to the intermediate transfer member 4 by the primary transfer devices 5 _Y , 5 _M , 5 _C and 5 _BK , respectively, to form primary transfer images. In that case, the intermediate transfer member 4
First, a yellow (Y) toner image is primarily transferred, and thereafter, a magenta (M) toner image, a cyan (C) toner image, and a black (BK) toner image are sequentially superimposed and primarily transferred. Therefore, the last black (B
After the primary transfer of the toner image of (K), the toner 13 _Y of yellow (Y) directly contacts the intermediate transfer member 4 on the intermediate transfer member 4 as shown in FIG. toner 13 _M of M), the toner 13 _C of cyan (C), and the toner 13 _BK black (BK) is in a state of being stacked in this order.

The primary transfer image on the intermediate transfer body 4 on which the four color toners are superposed in this way is secondarily transferred to the transfer material 6 such as paper by the secondary transfer device 7 to form a secondary transfer image. It is formed. In that case, in the secondary transfer image formed on the transfer material 6, the black (BK) toner 13 _BK comes into direct contact with the transfer material 6 as shown in FIG. Toner 13 _C , magenta (M) toner 13 _M ,
Then, the yellow (Y) toner 13 _Y is sequentially stacked.

Further, the secondary transfer image of the transfer material 6 on which the four color toners are superposed in this way is the heating roller 8a of the fixing device 8.
Is heated and fixed by. At this time, as shown in FIG. 3C, the yellow (Y) toner 13 _Y is the fixing surface facing toner that faces the fixing surface of the heating roller 8 a. By this heat fixing, a full-color image is formed on the transfer material 6.

By the way, the color image forming apparatus 1 of this example
Toner image forming apparatus 3 in_Y, 3 _M, 3_C, 3_BKUsed for
Each toner 13_Y, 13_M, 13_C, 13_BKAre both
Relatively contains THF insoluble component and cross-linking component
It has a molecular weight distribution curve that is difficult to melt and has two or more peaks.
Number average molecular weight (Mn) 2000-6000 and weight
Toner having an average molecular weight (Mw) of 15,000 to 50,000
Are formed from. THF is tetrahydrofuran
And is an organic solvent. Normally, toner molecular weight is measured by THF
Only soluble components are measured. But by the toner
Is a resin with a large molecular weight that does not dissolve in THF
Some are made by Therefore, insoluble in THF
The higher the content of the toner, the higher the content of the polymer.
It becomes difficult to be fixed.

Further, each toner image forming device 3 _Y , 3 _M , 3 _C , 3
Each developing unit 11 _Y of _{BK, 11 M, 11 C,} 11 toner 13 _Y is supplied to the _{BK, 13 M, 13 C,} 13 BK , each color of toner _{13 Y, 13 M, 13 C} , 13 BK In the state of being secondarily transferred onto the transfer material 6 in a state of being superposed on the transfer material 6, the external additive free ratio of the free external additive 15 _Y ′ in the toner 13 _Y of yellow (Y) which is the fixing surface facing toner is different from that of other colors. It is set so as to be smaller than the external additive free rate of the free external additives 15 _M ′, 15 _C ′, 15 _BK ′ in the toners 13 _M , 13 _C and 13 _BK and to be the minimum.

The external additive release rate of the toners 13 _Y , 13 _M , 13 _C , and 13 _BK of each color is most appropriately determined for the toner transferred to the transfer material 6 at the time of heat fixing. Since it is difficult to obtain the external additive release rate of the above toner 13 _Y , 13 _M , 13 _C , 13 _BK , each developing device 11 _Y , 11 _M , 1
Toners 13 _Y , 13 _M , 13 _C , 13 supplied to 1 _C , 11 _BK
By determining the external additive release rate of _BK , these external additive release rates can be determined more easily.

In the color image forming apparatus 1 of this example, the black (BK) toner 13 _BK is set so as to directly adhere to the transfer material 6, and the black (BK)
The toner 13 _BK of _{No. 3} is not set as the toner facing the fixing surface.

Furthermore, for the color image forming apparatus 1 of this example
4 color toners 13_Y, 13_M, 13_C, 13_BKThis
The same amount of mother particles 14 between these colors_Y, 14_M, 14_C, 1
Four_BKAgainst external additive 15_Y″, 15_M″, 15_C″, 15
_BK″ Amount is the same or almost the same, that is, the same as described later.
The slope of the period line (synchronous distribution graph) is the same or almost the same
Is set to. Therefore, the toner facing the fixing surface is
Yellow toner 13 _YThe external processing time of other color toner
-13_M, 13_C, 13_BKBy making it longer, yellow
Na 13_YOf the external additives of other colors of toner 13_M, 1
Three_C, 13_BKIs set to the minimum compared to the external additive release rate of
It

The amount of the free external additive 15 ', the external additive free ratio, the amount of the synchronous external additive 15 ", and the slope of the synchronous straight line (synchronous distribution graph) of the toner 13 of each color are, for example, a particle analyzer. It can be easily and more accurately determined by analyzing the adhesion state of the toner mother particles 14 and the external additive 15 by the toner analysis method using (PT1000).
In toner analysis using a particle analyzer (PT1000), the amount is represented by the number.

The toner analysis method using this particle analyzer is disclosed in detail in Japanese Patent Application Laid-Open No. 2000-047425, and since it can be understood by referring to this publication, a detailed description thereof is omitted here, but for the time being. ,
Briefly explained.

The toner base particles 14 and the external additive 1 obtained by this toner analysis method are plotted on a diagram in which the horizontal axis represents the equivalent particle size of the toner base particles 14 and the vertical axis represents the external additive 15.
By plotting the equivalent particle diameter of each equivalent particle of No. 5 for each particle of the toner 13, an equivalent particle diameter distribution chart of the toner particles is obtained. The state of adhesion of the external additive 15 to the toner mother particles 14 of the toner 13 is analyzed from this equivalent particle size distribution chart.
In that case, in this equivalent particle size distribution chart, one approximate straight line passing through the origin obtained by using the least squares method is obtained (for details, refer to the above-mentioned publication), the toner mother particles 14 and the external additive. The adhesion state with 15 is analyzed by the slope of this approximate straight line (that is, the synchronous distribution graph) (equivalent particle diameter of the external additive 15 / equivalent particle diameter of the toner mother particles 14).

By the way, the external additive 15 is used as the toner mother particles 14
4 (a), some of the external additives 15 are solidified and adhered to the toner base particles 14 sparsely over the entire surface thereof, as shown in FIG. 4 (a). As shown in (b), the external additive 15 may adhere to the toner mother particles 14 almost uniformly over the entire surface thereof. Now, assuming that the toner base particles 14 and the external additive 15 have the same amount in these synchronous toners, the external additive 15 shown in FIG.
4 has a relatively small inclination of the synchronization straight line (slope of the above-mentioned approximate straight line) in the synchronization toner, and the external additive 15 shown in FIG. 4B adheres to the toner base particles 14 substantially uniformly. The inclination of the synchronization straight line in the synchronization toner becomes relatively large. Therefore, the state of the synchronous toner can be known from the inclination of this straight line. Further, toners having the same inclination of the synchronization straight line have uniform charging characteristics, and have the same developing condition.

The toner mother particles 14 of the toner 13 used in the color image forming apparatus 1 of this example are toner mother particles obtained by a pulverization method and a polymerization method (hereinafter, the former is also a pulverization toner and the latter is a polymerization toner). Any of). As the pulverized toner, at least a pigment (coloring agent) is contained in a resin binder, a release agent and a charge control agent are added in some cases, and the mixture is uniformly mixed with, for example, a Henschel mixer as described later, and then biaxially extruded After being melted and kneaded by a machine, cooled, and then subjected to a coarse pulverization-fine pulverization process, an external additive is further externally added to the toner mother particles obtained by the classification treatment to obtain toner particles.

As the binder resin, known toner resins can be used, and examples thereof include polystyrene and poly-.
α-methylstyrene, chloropolystyrene, styrene-
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer Polymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester-methacrylic acid ester copolymer, styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, styrene- A styrene resin such as a vinyl methyl ether copolymer, which is a homopolymer or copolymer containing styrene or a styrene substitute, a polyester resin, an epoxy resin, a urethane modified epoxy resin, a silicone modified epoxy resin, a vinyl chloride resin, a rosin modified malein. Acid resin, phenyl tree , Polyethylene, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, etc. Alternatively, they can be mixed and used. Particularly in the present invention, styrene-acrylic acid ester-based resin, styrene-methacrylic acid ester-based resin, and polyester resin are preferable. In the present invention, the binder resin has a glass transition temperature of 50 ° C to 75 ° C and a flow softening temperature of 10 ° C.
The range of 0 ° C to 150 ° C is preferable.

As the colorant, a known colorant for toner can be used. For example, carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6G, calco oil blue, quinacridone, benzidine yellow, rose bengal, malachite green lake, Quinoline yellow, C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment Red 122, C.I. I.
Pigment Red 57: 1, C.I. I. Pigment Red 184, C.I. I. Pigment Yellow 12, C.I.
I. Pigment Yellow 17, C.I. I. Pigment
Yellow 97, C.I. I. Pigment Yellow 180,
C. I. Solvent Yellow 162, C.I. I. Pigment Blue 5: 1, C.I. I. Pigment Blue 1
Dyes and pigments such as 5: 3 can be used alone or in combination.

As the release agent, a known release agent for toner can be used. Examples thereof include paraffin wax, microwax, microcrystalline wax, cadilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax and oxidized polypropylene wax. Among them, polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like are preferably used.

As the charge adjusting agent, known charge adjusting agents for toner can be used. For example, oil black, oil black BY, Bontron S-22 {produced by Orient Chemical Industry Co., Ltd.}, Bontron S-34 {produced by Orient Chemical Industry Co., Ltd.}, salicylic acid metal complex E-81 {Orient Chemical Industry Co., Ltd.) , Thioindigo pigments, sulfonylamine derivatives of copper phthalocyanine, Spiron Black TRH {produced by Hodogaya Chemical Co., Ltd.}, calixarene compounds, organic boron compounds, fluorine-containing quaternary ammonium salt compounds, monoazo metal complexes, Examples thereof include aromatic hydroxylcarboxylic acid-based metal complexes, aromatic dicarboxylic acid-based metal complexes, and polysaccharides. Among them, colorless or white ones are preferable for color toners.

Regarding the component ratio (weight ratio) in the pulverized toner, the colorant is 0.5 to 15 parts by weight, preferably 1 to 1 part by weight, relative to 100 parts by weight of the binder resin.
0 parts by weight, the release agent is 1 part by weight to 10 parts by weight, preferably 2.5 parts by weight to 8 parts by weight, and
The charge control agent is 0.1 to 7 parts by weight, preferably 0.5.
It is from 5 to 5 parts by weight. The pulverized toner thus obtained has an average particle size of 5 μm to 10 μm, preferably 6 μm to 9 μm.

In order to improve the transfer efficiency, the pulverized toner of the present invention may be spheroidized, and for that purpose, a device capable of pulverizing in a relatively round spherical shape in the pulverizing step. For example, if you use a turbo mill known as a mechanical crusher {made by Kawasaki Heavy Industries, Ltd.}, the circularity will be 0.9.
Up to 3 is possible. Alternatively, if the crushed toner is used in a commercially available hot air spheronizer, surfusing system SFS-3 type (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), the circularity can be up to 1.00.

Further, the polymerization toner includes suspension polymerization method, emulsion polymerization method and the like. In the suspension polymerization method, a polymerizable monomer (monomer), a color pigment, and a release agent are further added, and if necessary, a mixture containing a dye, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives is added. The dissolved or dispersed monomer composition is added to a water phase containing a suspension stabilizer (water-soluble polymer, poorly water-soluble inorganic substance) with stirring, granulated, and polymerized to obtain desired particles. Colored polymerized toner particles having a size can be formed.

Further, in the emulsion polymerization method, a monomer and a release agent are further dispersed in water if necessary, and a polymerization initiator, an emulsifier (surfactant), etc. are dispersed in the polymerization to carry out the polymerization. Colored toner particles having a desired particle size can be formed by adding a charge control agent and an aggregating agent (electrolyte). Regarding the materials used for preparing the polymerized toner, the same materials as those for the pulverized toner described above can be used for the colorant, the release agent, the charge control agent, and the fluidity improver.

As the polymerizable monomer (monomer), a known vinyl-based monomer can be used. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p -Methoxystyrene, p-ethylstyrene, vinyltoluene, 2,4-
Dimethylstyrene, pn-butylstyrene, p-phenylstyrene, p-chlorostyrene, divinylbenzene, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate. , Dodecyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, methacrylic acid n
-Octyl, dodecyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid,
Ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propyleneate, acrylonitrile, methacrylonitrile, vinylmethyl Ether, vinyl ethyl ether, vinyl ketone,
Examples thereof include vinyl hexyl ketone and vinyl naphthalene. Examples of the fluorine-containing monomer include 2,2
2-trifluoroethyl acrylate, 2,2,3,3
-Tetrafluoropropyl acrylate, vinylidene fluoride, ethylene trifluoride, tetrafluoroethylene, trifluoropropylene and the like can be used because the fluorine atom is effective for negative charge control.

Known emulsifiers (surfactants) can be used. For example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride. , Hexadecyltrimethylammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether and the like.

As the polymerization initiator, known ones can be used. For example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, etc. is there.

Known coagulants (electrolytes) can be used. Examples thereof include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, iron sulfate and the like.

Even in the case of the polymerized toner of the present invention, for the purpose of improving the transfer efficiency, it is preferable that the toner is spheroidized,
As a method of adjusting the circularity of the toner by the polymerization method, the emulsion polymerization method can freely change the circularity by controlling the temperature and the time during the aggregation process of the secondary particles, and the range is 0.94 to.
It is 1.00. In addition, in the suspension polymerization method, since a spherical toner is possible, the circularity is in the range of 0.98 to 1.00. Further, by heating and deforming the toner at a temperature higher than the Tg temperature of the toner in order to adjust the circularity, the circularity becomes 0.94 to 0.9.
It is possible to freely adjust up to 8.

Polymerization toner can be prepared by a dispersion polymerization method other than the above-mentioned method, for example, JP-A-63-30400.
It can also be produced by the method disclosed in Japanese Patent Publication No. In this case, since the shape is close to a true sphere, in order to control the shape, it is possible to press the toner at a temperature higher than the Tg temperature to obtain a desired toner shape. In this way, the obtained polymerized toner has an average particle diameter of 4 μm to 9 μm, preferably 4.5 μm to 8 μm. In the present invention, the average particle diameter and circularity of toner particles and the like are values measured by FPIA2100 manufactured by Sysmex Corporation.

Further, as the external additive 15 of the toner 13,
Silica, titanium dioxide, alumina, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride,
Fine particles of magnetite, molybdenum disulfide, aluminum stearate, magnesium stearate, zinc stearate, calcium stearate, metal titanate, and silicon metal salt, each having an average primary particle size of 1 to 500.
nm, preferably 5-200 nm can be used.
However, it is preferable to contain an element that is rarely contained in the composition of the mother particles so that it can be detected by PT-1000.

Then, these toner mother particles 14 _Y , 14
_M , 14 _C , 14 _BK and external additive 15 _Y , 15 _M , 15 _C , 15 _BK
The toner 13 of each color is manufactured by using the respective. First, toner mother particles 14 _Y , 14 _M , 14 _C , and 14 _{BK of} respective colors are manufactured. Regarding cyan toner mother particles 14 _C , for example, polycondensation polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A is used. 50:50 (weight ratio) mixture 100 of partially cross-linked product of polyvalent metal compound
Parts by weight, 5 parts by weight of cyan pigment phthalocyanine blue,
The release agent has a melting point of 152 ° C. and a weight molecular weight Mw of 400.
3 parts by weight of polypropylene of 0 and 2 parts by weight of salicylic acid metal complex E-81 (manufactured by Orient Chemical Industry Co., Ltd.) as a charge control agent were uniformly mixed using a Henschel mixer 20C, and then kneaded by a twin-screw extruder. And cooled. Chilled toner is crushed with a jet mill and classified with an airflow classifier. Cyan toner mother particles with an average particle size of 8 μm 14 _C
Can be obtained.

Further, toner mother particles 14 _Y , 14 _M ,
For 14 _BK , for example, this cyan toner mother particle 1
In the production method of 4 _C , a pigment is used for each of magenta mother particles 14 _M , quinacdrine, yellow toner mother particles 14 _Y , pigment yellow 180, and black toner mother particles 14 _BK , carbon black. The toner mother particles 14 _Y , 14 _M , and 14 _BK of each color can be obtained by the same manufacturing method as the toner mother particles 14 _C.

Next, the external additive 15 is added to the toner mother particles 14 _Y , 14 _M , 14 _C , and 14 _BK of the respective colors obtained as described above, and the toners 13 _Y , 13 _M , 13 _C , of the respective colors are added. 13 _BK is manufactured. For each color toner, silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area 141 m ² / g, volume resistivity 1
0 ¹⁵ Ω · cm, average particle diameter of primary particles 12 nm) 0.5
The toner of each color can be produced by adding the mixture to a Henschel mixer (20 liters) at a ratio of up to 2.5 parts by weight and externally adding it at a rotation speed of 2850 rpm for a processing time of 1 to 4 minutes.

According to the color image forming apparatus 1 of this example,
Yellow (Y) toner 13 _Y that is the toner facing the fixing surface
The external additive release rate of the free external additive 15 _Y ′ in the other toners 13 _M , 13 _C and 13 _BK of the free external additive 15 _M ′,
Since the external additive liberation rate of 15 _C ′ and 15 _BK ′ is set to be the minimum and the minimum, the heating roller 68 of the fixing device 8 is set.
The amount of free external additive existing between the fixing surface and the toner is relatively small. As a result, the heat from the heating roller 8a is effectively transferred to the toner mother particles _14Y . Therefore, the temperature of the toner mother particles 14 _Y is controlled more appropriately, and the occurrence of low temperature offset can be prevented. In particular, in a toner in which toner base particles containing a THF-insoluble component that is difficult to dissolve by heat and a cross-linking component are used, the occurrence of low temperature offset can be more effectively prevented.

In this case, the yellow toner which is the toner facing the fixing surface.
-(Y) toner 13_YThe external additive release rate of
With this toner 13_YThe free external additive of
As described above, the four-color toner 13_Y, 13_M, 13_C, 13_BKof
Between the same amount of mother particles 14 _Y, 14_M, 14_C, 14_BKAgainst
Then, the external additive 15_Y″, 15_M″, 15_C″, 15_BK″ Amount
Are set to be the same or almost the same, so other toner
Thirteen_M, 13_C, 13_BKYellow (Y) toner 1
Three_YExternal additive 15_Y″ Is mother particle 14_YEvenly and evenly
By covering, toner 13_YIs an external additive 15_YImproved by
It says that it has high toner quality and high image quality.
There is no end.

Furthermore, the external additive release rates of the yellow, magenta, cyan, and black toners 13 _Y , 13 _M , 13 _C , and 13 _BK are respectively determined by the corresponding developing devices 11 _Y , 11 _M , and 11 _B.
Since the external additive release rate of the toner supplied to _C , 13 _BK is defined, the external additive release rate of each toner 13 _Y , 13 _M , 13 _C , 13 _BK can be set more easily. .

Further, the toner mother particles 14 _Y , 14 _M , 1 of each color are
External additive 15 _Y ″, 15 _M ″, attached to 4 _C and 14 _BK ,
The amount of 15 _C ″ and 15 _BK ″ is set to the same, that is,
Since the inclinations of the synchronization straight lines (approximate straight lines) obtained by the toner analysis method using the PT analyzer disclosed in the above-mentioned Japanese Laid-Open Patent Publication are set to be the same, four color toners 1
It is possible to make the respective charging characteristics of No. 3 uniform and to make the developing conditions the same. Since the developing conditions can be the same, the attitude of the developing device for each color with respect to the image carrier and the shape of each developing device can be the same, and the developing bias can be the same. Accordingly, as described above, various developing methods can be flexibly and effectively adopted according to the purpose.

If the black (BK) color toner image forming device 3 _BK is disposed at the most downstream side in the moving direction of the intermediate transfer member 4, other yellow (Y), magenta (M), and cyan are obtained. The arrangement order of the toner image forming devices 3 _Y , 3 _M , and 3 _C of each color of (C) can be set in any order. In that case, the amount of the toner 13 of the color of the toner image forming apparatus located at the most upstream side in the moving direction of the intermediate transfer body 4, that is, the amount of the free external additive 15 ′ of the toner 13 of the color first transferred to the intermediate transfer body 4. Is smaller than the amount of the free external additive 15 ′ of the toner 13 of the other color (that is, the external additive free ratio of the toner 13 of the color first transferred to the intermediate transfer member 4 is the same as that of the toner 13 of the other color). It should be set so that it is less than the external additive release rate.

Further, the color image forming apparatus 1 of the present invention is
As shown in FIG. 5, a tandem system that does not use the intermediate transfer body 4
It can also be applied to the color image forming apparatus 1. This
In the case of the color image forming apparatus 1 of the example of FIG.
Image carrier 9 of each color without _Y, 9_M, 9_C, 9_BKFrom now on
And the toner image of the corresponding color is directly transferred to the transfer material 6.
Therefore, unlike the above example, a black (K) toner image is formed.
Device 3_BKIs placed on the most upstream side in the moving direction of the transfer material 6.
The yellow (Y) toner image forming device 3_YTransfer material 6
Is arranged on the most downstream side in the moving direction of. According to
As shown in FIG. 3B, the transfer material 6 conveyed to the fixing device 8 is
And black (BK) toner 1 as shown in (c) and
Three_BKDirectly adheres to the fixing surface of the heating roller 8a
-(Y) toner (toner facing the fixing surface) 13_YAdheres
Become so.

In this case, as in the above-described example, the external additive release rate of the free external additive 15 _Y ′ in the yellow (Y) toner 13 _Y is set smaller than the free external additive release rate of other toners. Has been done.

As in the above example, yellow (Y),
The arrangement order of the magenta (M) and cyan (C) toner image forming devices 3 _Y , 3 _M , and 3 _C is arbitrary, but the toner image forming is arranged on the most downstream side in the moving direction of the transfer material 6. Device 3
It goes without saying that the external additive release rate of the toners 13 _Y , 13 _M and 13 _C of _Y , 3 _M and 3 _C is set to be the smallest. Other configurations and other effects of the color image forming apparatus 1 of this example are substantially the same as those of the above example.

Further, the color image forming apparatus 1 of the present invention is
As shown in FIG. 6, the image carrier 9 is not provided for each color, but one image carrier (photosensitive drum) 9 common to each color is provided and the image carrier 9 (photosensitive drum) 9 is provided. ,
It is also applicable to the color image forming apparatus 1 in which the developing devices 11 _Y , 11 _M , 11 _C and 11 _BK for the respective colors are sequentially arranged from the upstream side along the rotation direction of the image carrier 9. In the case of the color image forming apparatus 1 of this example, either the secondary transfer type color image forming apparatus 1 including the intermediate transfer body 4 or the primary transfer type only color image forming apparatus 1 not including the intermediate transfer body 4 is used. Can also be adopted.

Then, yellow (Y) and magenta
(M), cyan (C), and black (BK)
Imager 11_Y, 11_M, 11_C, 11_BKThe order of placement is
Similarly, black (BK) toner 13 is applied to the transfer material 6._BKBut
Directly attached to the transfer material 6 and the remaining yellow (Y),
Magenta (M) and cyan (C) toners 13_Y,
Thirteen _M, 13_COf the fixing surface pair that is located closest to the fixing surface
It is set so that the external additive release rate of the toner is minimized.
Be done. Another configuration of the color image forming apparatus 1 of this example and
Other functions and effects are substantially the same as those of the above-described examples.

Furthermore, the color image forming apparatus 1 of the present invention is
Each color developing device 11 shown in FIG._Y, 11 _M, 11_C, 11_BKTimes
A rotary type color image forming apparatus 1 which rolls and
Each color developing device 11 shown in FIG._Y, 11_M, 11_C, 11_BKStraight
Suitable for slide type color image forming apparatus 1 that moves linearly
Can be used.

In this case, the arrangement order of the yellow (Y), magenta (M), cyan (C), and black (BK) developing units 11 _Y , 11 _M , 11 _C , and 11 _BK is at least during heat fixing. It suffices to set any one of the toners other than the black (BK) toner _13BK so as to face the fixing surface of the heating roller 8a. Other configurations and other effects of the color image forming apparatus 1 of these examples are substantially the same as those of the above-described examples.

Next, an embodiment of the color image forming apparatus 1 of this example will be described. Toner low temperature offset experiments were conducted on two examples belonging to the present invention and one comparative example not belonging to the present invention. In the toner 13 used in this experiment, the toner mother particles for each color contained 1 to 40 wt% of the THF insoluble component, had a molecular weight distribution curve having two peaks, and had a number average molecular weight (Mn) of 2000 to 600.
0 and weight average molecular weight (Mw) 15000-5000
The toner is relatively insoluble in heat of 0. To measure the THF-insoluble matter, about 1 g of a toner sample is weighed and dissolved in THF at room temperature overnight. The supernatant is separated by centrifuging the solution. After the remaining residue is dried, the weight is measured and the content of the THF insoluble matter is calculated.

The toner of the example is manufactured as follows.
It was That is, the first layer (facing the fixing surface) of the yellow toner
Thirteen_YAbout 100 parts by weight of yellow toner mother particles
On the other hand, the surface was treated with hexamethyldisilazane.
Silica fine particles (BET specific surface area 141m²/ G, volume resistivity
10¹⁵Ω · cm, average particle size of primary particles 12 nm) 1.
Henschel mixer (20 liters) at a ratio of 5 parts by weight
, And at a rotation speed of 2850 rpm for a processing time of 3 minutes
The yellow toner 13 of the example which has been subjected to external addition treatment _YAnd

The second to fourth layers of magenta toner 1
For 3 _M , cyan toner 13 _C, and black toner 13 _BK , silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area 141 m ² / g, volume resistivity 10
¹⁵ Ω · cm, average particle diameter of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a ratio of 1.5 parts by weight, and externally added at a rotation speed of 2850 rpm for a processing time of 1 minute. magenta toner 13 _M of, and the cyan toner 13 _C and black toner 13 _BK.

Further, the toner of the example was manufactured as follows. That is, with respect to the first layer (facing the fixing surface) of the yellow toner 13 _Y , the yellow toner mother particles 100
Silica fine particles surface-treated with hexamethyldisilazane based on parts by weight (BET specific surface area 141 m ² / g, volume resistivity 10 ¹⁵ Ω · cm, average particle diameter of primary particles 12 nm)
Was charged into a Henschel mixer (20 liters) at a ratio of 1.5 parts by weight, and external addition treatment with 3 minutes of processing time at a rotation speed of 2850Rpm, was yellow toner 13 _Y Examples.

The second and third layers of magenta toner 1
For 3 _M and cyan toner 13 _C , silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area 141 m ² / g, volume resistivity 10 ¹⁵ Ω · cm) were used with respect to 100 parts by weight of each toner mother particle. , Primary particles having an average particle diameter of 12 nm) were added to a Henschel mixer (20 liters) at a ratio of 1.5 parts by weight and 2850 rpm.
External processing was performed for 1 minute at a rotational speed of 1 to obtain magenta toner 13 _M and cyan toner 13 _C of the example.

On the other hand, the toner of Comparative Example was manufactured as follows. That is, with respect to the first layer (facing the fixing surface) of the yellow toner 13 _Y , the yellow toner mother particles 100
Silica fine particles surface-treated with hexamethyldisilazane based on parts by weight (BET specific surface area 141 m ² / g, volume resistivity 10 ¹⁵ Ω · cm, average particle diameter of primary particles 12 nm)
Was charged into a Henschel mixer (20 liters) at a ratio of 1.5 parts by weight, and external addition treatment in 1 minute treatment time at a rotation speed of 2850Rpm, was yellow toner 13 _Y of the comparative example.

The second and third layers of magenta toner 1
For 3 _M and cyan toner 13 _C , silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area 141 m ² / g, volume resistivity 10 ¹⁵ Ω · cm) were used with respect to 100 parts by weight of each toner mother particle. , Primary particles having an average particle diameter of 12 nm) were added to a Henschel mixer (20 liters) at a ratio of 1.5 parts by weight and 2850 rpm.
External processing was performed at a rotation speed of 2 minutes for a processing time of 2 minutes to obtain magenta toner 13 _M and cyan toner 13 _{C of} the comparative example.

The image forming apparatus used in the experiment is the tandem type image forming apparatus shown in FIG. 1, and the transfer material 6 used is ordinary paper. Table 1 shows the release rate of the external additive and the experimental result of each color toner in each of the examples and the comparative examples.

[0075]

[Table 1]

In Table 1, in the examples, the first layer (fixing surface side) toner (toner facing the fixing surface) is yellow (Y) toner 13 _Y , and the second layer toner is magenta (M). Toner 13 _M , the third layer toner is cyan (C) toner 13 _C , and the fourth layer (paper side) toner is black (BK) toner 13 _BK . It should be noted that the first to fourth layers represent the layers of toner of the colors located in order from the top in FIG. In the examples and the comparative examples, the toner of the first layer (fixing surface side) (toner facing the fixing surface) is yellow (Y) toner 13.
Is _Y, also a second layer of the toner is the toner 13 _M of magenta (M), the toner of the further third layer (paper side) are toner 13 _C of cyan (C).

As shown in Table 1, in the examples, the external additive release rate of the first layer yellow toner 13 _Y is 0.50%, and the external additive release rate of the second layer magenta toner 13 _M is 0.5%. 89
%, The external additive release rate of the third layer cyan toner 13 _C is 0.8.
The external additive release rate of the black toner _13BK of the fourth layer is 5% and is 0.88. In the example, the external additive release rate of the first layer yellow toner 13 _Y is 0.45%, the external additive release rate of the second layer magenta toner 13 _M is 0.89%, and the third layer cyan is The release rate of the external additive in Toner 13 _C is 0.98%. Further, in the comparative example, the first-layer yellow toner 13
The external additive release rate of _Y is 1.01%, the external additive release rate of the second layer magenta toner 13 _M is 0.66%, and the external additive release rate of the third layer cyan toner 13 _C is 0.6%. 69%.

The external additive release rate for each color is the external additive for each toner 13 _Y , 13 _M , 13 _C , 13 _BK supplied to each developing unit 11 _Y , 11 _M , 11 _C , 11 _BK. It was calculated from the amount of free external additive actually present on the fixing surface from the agent release rate.
At this time, the maximum development amount of each of the toners 13 _Y , 13 _M , 13 _C and 13 _BK was also measured. As an example, Table 2 shows the free external additive amount calculated from the external additive free rate and the maximum development amount of each color obtained in the above-described Examples.

[0079]

[Table 2]

In Table 2, the maximum development amount was measured from the photoconductor which is the image bearing member. The maximum transfer efficiency is 95% for both primary transfer and secondary transfer. Furthermore, the maximum total amount of external additives released was rounded off to the third decimal place.

As shown in Table 1, as a result of the experiment, the temperature at which the low-temperature offset appeared at the time of heat fixing was 150 ° C. in the example and 160 ° C. in the example, while 130 in the comparative example. It was ℃. As is clear from the experimental results, the appearance temperature of the low-temperature offset is relatively high in the examples and the present invention, and the appearance temperature of the low-temperature offset is low in the comparative examples not belonging to the present invention. It has been found that the occurrence of is effectively prevented.

Next, the charging characteristics of the toner were tested for the above-mentioned examples belonging to the present invention and the above-mentioned comparative examples not belonging to the present invention. In that case, the toner charging characteristic test was performed by measuring the toner charge amount. The toner charge amount is measured by adjusting the toner sample and carrier (FL184-15) so that the toner sample concentration becomes 3 wt%.
0 / manufactured by Powder Tech) and mixed at 100 rpm
Stir for 15 minutes to charge the toner. Then, the toner charge amount was measured using a small charge amount measuring device (Model 210HS-2 / made by Trek). Table 3 shows the obtained results of the inclination of the synchronization straight line (synchronization distribution graph) of the toners of the respective colors and the measurement results of the charge amount in Examples and Comparative Examples.

[0083]

[Table 3]

As shown in Table 3, in the example, the synchronization line of the yellow (Y) toner 13 _Y (synchronization distribution graph)
Has a slope of 0.604, the slope of the sync line of the toner 13 _M of magenta (M) (sync distribution graph) is 0.622, and the slope of the sync line of the toner 13 _C of cyan (C) (sync distribution graph) is 0. .605, and the inclinations of the three colors are almost the same. In the comparative example, the yellow (Y) toner 13 is used.
The slope of the _Y sync line (sync distribution graph) is 0.432, the sync line of the magenta (M) toner 13 _M is 0.751, and the sync line of the cyan (C) toner 13 _C is The slope of the (synchronous distribution graph) is 0.521, and there are considerable variations in the slopes of the three colors.

As a result of the measurement of the charge amount, in the example,
Low (Y) toner 13_YThe amount of charge on the battery is -22.
g, magenta (M) toner 13_MThe amount of charge is -1.8
μC / g, cyan (C) toner 13_CCharge amount is -2
2.1 μC / g, the three colors have almost the same charge amount.
It was In the comparative example, the yellow (Y) toner 13 is used.
_YToner of -13.1 μC / g and magenta (M)
-13_MOf the charge amount of −26.6 μC / g and cyan (C)
Toner 13_CCharge amount is -16.1 μC / g, 3 colors
There was a considerable variation in the amount of charge. This measurement result
As is clear from the above, in the examples belonging to the present invention,
Comparative example in which characteristics are almost uniform and does not belong to the present invention
Then, it was found that the charging characteristics were different for each color.

The color image forming apparatus 1 of each of the above examples
In each of the above, a full-color image is formed using four color toners of yellow (Y), magenta (M), cyan (C), and black (BK).
The present invention is one in which heat fixing is performed, and at least black
The toner 13 _{BK of} K) can be applied to any color image forming apparatus as long as it forms a color image using a plurality of color toners of two or more colors that are not located in the first layer.

[0087]

As is apparent from the above description, according to the color image forming apparatus of the present invention, the fixing surface facing toner is set to be a toner of at least a color other than black, and the fixing surface facing toner is composed of mother particles. Since the release rate of the external additive of the released external additive of the fixing surface facing toner is set to be smaller than the external additive release rate of the toner of the other color, the fixing surface facing toner existing between the fixing surface and The amount of free external additive can be reduced. This allows the heat from the fixing member to be effectively transferred to the base particles. Therefore, the temperature of the mother particles can be controlled more appropriately, and the occurrence of low temperature offset can be prevented.

In particular, according to the invention of claim 2, the external additive release rate of the toners of a plurality of colors is defined by the external additive release rate of the toners supplied to the corresponding developing devices.
It becomes possible to more easily set the external additive release rate of toners of a plurality of colors. According to the third aspect of the invention, since yellow, magenta, cyan, and black toners are used as the toners of a plurality of colors, respectively, a high-quality full-color image can be obtained.

Further, according to the invention of claim 4, the amount of the external additive adhering to the mother particles is set to be the same or substantially the same among the toners of a plurality of colors.
Since the inclination of the synchronization straight line (approximate straight line) obtained by the toner analysis method using the PT analyzer disclosed in Japanese Patent Application Laid-Open No. 047425 is set to be the same, the charging characteristics of the toners of a plurality of colors are uniform or almost uniform. In addition to being uniform, the developing conditions can be the same or almost the same. Therefore, the postures of the developing devices of the respective colors with respect to the image carrier and the shapes of the developing devices can be formed to be the same, and the developing bias can be set to be the same. As a result, various developing methods can be flexibly and effectively adopted according to the purpose.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a full-color intermediate transfer type color image forming apparatus which is an example of an embodiment of a color image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a state of attachment of an external additive to mother particles of toner.

3 shows a state in which four color toners are overlapped in the color image forming apparatus shown in FIG. 1, and FIG. 3A shows a state in which four color toners are intermediately transferred (primarily transferred) from an image carrier to an intermediate transfer member. FIG. 6B is a diagram showing a state in which four color toners are secondarily transferred from the intermediate transfer member to the transfer material, and FIG. 6C is a diagram showing a state of the four color toners on the transfer material during heat fixing. is there.

FIG. 4 is a diagram showing a state in which an external additive is attached to a mother particle of a toner analyzed by a particle analyzer, FIG. 4A is a diagram showing a case where an inclination of a synchronization straight line in which the external additive is attached to the mother particle is small, and FIG. FIG. 4 is a diagram showing a case where a slope of a synchronization straight line in which an external additive is attached to a mother particle is large.

FIG. 5 is a diagram schematically and partially showing another example of the embodiment of the present invention.

FIG. 6 is a diagram schematically showing still another example of the embodiment of the present invention.

FIG. 7 is a diagram schematically and partially showing still another example of the embodiment of the present invention.

FIG. 8 is a diagram schematically and partially showing still another example of the embodiment of the present invention.

[Explanation of symbols]

1 ... Image forming apparatus, 2 ... Exposure apparatus, 3_Y, 3_M, 3_C, 3_BK…
Toner image forming device, 4 ... Intermediate transfer member, 5_Y, 5_M, 5_C, 5_BK
... (primary) transfer device, 6 ... transfer material, 7 ... secondary transfer device,
8: fixing device, 8a: heating roller (fixing member), 9_Y, 9_M,
9_C, 9_BK... Image carrier, 10_Y, 10_M, 10_C, 10_BK... charged
Bowl, 11_Y, 11_M, 11_C, 11_BK… Developer, 12… Cree
Device, 13,13_Y, 13_M, 13_C, 13_BK… Tona
ー 、 14,14 _Y, 14_M, 14_C, 14_BK… Mother particles, 14 '
… Asynchronous mother particles, 15,15_Y, 15_M, 15_C, 15_BK... outside
Additive, 15 ', 15_Y'15_M'15_C'15_BK’… Yu
External Additive, 15 ", 15_Y″, 15_M″, 15_C″, 15_BK″
… Synchronous external additives

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/20 101 G03G 9/08 361 (72) Inventor ▲ Takano Hidehiro 3 Yamato, Yamato, Suwa-shi, Nagano No. 3 No. 5 Seiko - Epson Corporation in the F-term (reference) 2H005 AA08 AA21 AB10 CA17 CA21 EA07 FB01 2H033 AA09 AA10 AA11 BA58 BB01 BB28 2H300 EB02 EB04 EB07 EB08 EB12 EC02 EC05 EF03 EG02 EH16 EJ09 EJ12 EJ15 EJ16 EJ45 EJ47 EK03 EK05 EL07 GG11 GG17 GG43 GG47 HH22 HH23 KK03 KK06 KK08 KK14 MM06 MM10 MM11 MM13 MM24 MM25 MM28 MM29

Claims (4)

[Claims] 1. A toner of multiple colors including at least black, each of which is composed of a large number of mother particles containing a THF insoluble component and a large number of particles of an external additive attached to these mother particles, is superposed on a transfer material. In a color image forming apparatus that forms a color image by heating and fixing these toners by a fixing member, the fixing of the fixing member is the most among the plurality of color toners attached to the transfer material during the heat fixing. The fixing surface facing toner of the color located on the surface side is a toner of at least a color other than black, and is an external additive of the fixing surface facing toner, which is a free external addition liberated from the mother particles of the fixing surface facing toner. A color image forming apparatus, wherein the release rate of the external additive of the agent is set to be smaller than the release rate of the external additive of the toner of another color. 2. The color image according to claim 1, wherein the external additive release rates of the toners of the plurality of colors are the external additive release rates of the toners supplied to the corresponding developing devices, respectively. Forming equipment. 3. The toners of a plurality of colors are yellow, magenta, cyan and black toners, respectively, and the fixing surface facing toner is any of yellow, magenta and cyan toners. The color image forming apparatus according to claim 1. 4. The amount of the external additive adhering to the mother particles is set to be the same or substantially the same among the toners of the plurality of colors. 1. The color image forming apparatus described in 1.