JP2003280330A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain satisfactory secondary transfer characteristics when carrying out a secondary transfer of toner having a plurality of colors on a transfer material through an intermediate transfer body by effectively improving the secondary transfer efficiency of the toner. <P>SOLUTION: In the secondary transfer, the toner having four colors of magenta, cyan and black is sequentially superposed on an intermediate transfer body 4 to carry out a primary transfer, and then the secondary transfer is carried out on the transfer material 6. At that time, the yellow (Y) toner 13Y is toner facing the intermediate transfer body 4. The external additive isolation rate of the yellow toner 13Y being the toner facing the intermediate transfer body is larger than the external additive isolation rates of the toner 13M, 13C and 13BK of other colors, and is set to the maximum. Thereby, the isolation external additives of the toner 13Y existing between the toner 13Y and the intermediate transfer body 4 increases, which improves secondary transfer efficiency. <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. Belonging to the technical field of the forming device, in particular, the toners of a plurality of colors are superposed on the intermediate transfer body and primary-transferred, and the toners on the intermediate transfer body are secondarily transferred to a transfer material, and the plural colors superposed on the transfer material. Belongs to the technical field of a color image forming apparatus that fixes to other toners.

[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 the image forming apparatus, the toner image on which the electrostatic latent image is developed is transferred to a transfer material such as paper and then fixed to form an image on the transfer material. It In that case, start a full-color image forming device,
In a color image forming apparatus in which toners of a plurality of colors are transferred onto a transfer material and then fixed, the toners of a plurality of colors are transferred onto the intermediate transfer body to be primary-transferred, and the toners on the intermediate transfer body are transferred to the transfer material as a secondary transfer. There is a color image forming apparatus that transfers and fixes toners of a plurality of colors that are superposed on the transfer material.

In such a color image forming apparatus, when the toner on the intermediate transfer member is secondarily transferred to the transfer material, a part of the toner remains on the intermediate transfer member, and good secondary transfer is performed. Sometimes there is not.

Therefore, as disclosed in both of the above publications, it is considered that the secondary transfer efficiency of the toner is improved by improving the secondary transfer characteristic of the toner by improving the toner characteristics. .

First, considering the improvement of the secondary transfer characteristics of the toner 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. The added external additives all 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 that secondarily transfers toners of a plurality of colors onto a transfer material through an intermediate transfer body, the secondary transfer efficiency is improved. Is difficult to improve.

Further, considering the improvement of the secondary transfer characteristics of the toner by the improvement of the toner characteristics disclosed in the above-mentioned JP-A-6-324525, in the improvement of the toner characteristics disclosed in this publication, the toner characteristics of each color are improved. 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 that secondarily transfers toners of a plurality of colors onto a transfer material through an intermediate transfer body, the secondary transfer efficiency is improved. Is difficult to improve.

Further, in a color image forming apparatus that secondarily transfers toners of a plurality of colors onto a transfer material via an intermediate transfer member, the charging characteristics of the toners of the plurality of colors are made as uniform as possible and the developing conditions are the same. However, in the improvement of the toner characteristics disclosed in both of the above-mentioned publications, since the attachment state of the external additive to the mother particles is not properly taken into consideration, each charging of the toners of a plurality of colors is performed. Another problem is that it is difficult to make the characteristics as uniform as possible.

The present invention has been made in view of the above circumstances, and an object thereof is to form a toner image in a color image formation in which toners of a plurality of colors are secondarily transferred to a transfer material via an intermediate transfer member. It is an object of the present invention to provide a color image forming apparatus capable of effectively improving secondary transfer efficiency and obtaining good secondary transfer characteristics.

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

[0014]

In order to solve this problem, the color image forming apparatus according to the invention of claim 1 has a large number of mother particles and a large number of external additives attached to these mother particles. A plurality of color toners consisting of particles of the above are superposed on the intermediate transfer member to be primarily transferred, and the toners on the intermediate transfer member are secondarily transferred to the transfer material, and the toners on the transfer material are fixed to form a color image. In the color image forming apparatus for forming a toner image, the toner externally added to the intermediate transfer member facing toner of the color that is closest to the intermediate transfer member and faces the intermediate transfer member among the toners of the plurality of colors attached to the intermediate transfer member. The external additive liberation rate of free external additives liberated from the mother particles of the intermediate transfer member facing toner is 0.2% or more, and the external additive liberation rate of toners of other colors is It is set smaller It is characterized by.

According to the second aspect of the present invention, the toners of a plurality of colors, each of which is composed of a large number of mother particles and a large number of particles of the external additive attached to the respective mother particles, are superposed on the intermediate transfer member to form a primary toner. In a color image forming apparatus that transfers and secondarily transfers the toner on the intermediate transfer member to a transfer material and fixes the toner on the transfer material to form a color image, Of the toners of a plurality of colors, it is an external additive for the intermediate transfer member facing toner of the color that is located closest to the intermediate transfer member and faces the intermediate transfer member, and is released from the mother particles of the intermediate transfer member facing toner. It is characterized in that the external additive free rate of the free external additive is set to be higher than the external additive free rate of the toners of other colors.

Further, the invention of claim 3 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, the invention of claim 4 is characterized in that the toners of a plurality of colors are yellow, magenta, cyan and black toners, respectively, and the intermediate transfer member facing toner is any one of these toners. I am trying. Furthermore, the invention of claim 5 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.

[0018]

In the color image forming apparatus of the present invention thus constructed, the external additive liberation rate of the free external additive liberated from the mother particles of the toner facing the intermediate transfer body facing the intermediate transfer body is 0.2. % Or more, and the external additive liberation rate of toners of other colors is set to be smaller, or the amount of free external additive liberated from the mother particles of the intermediate transfer member facing toner facing the intermediate transfer member is set. The external additive release rate is set to be higher than the external additive release rate of toners of other colors.

As a result, the amount of free external additive existing between the intermediate transfer member and the intermediate transfer member is relatively large.
This free external additive reduces the possibility that the mother particles of the toner facing the intermediate transfer body will come into contact with the intermediate transfer body.
The image force acting on the toner is reduced, and the electric adhesion between the intermediate transfer body and the toners of a plurality of colors is reduced, so that the peelability of the toners of a plurality of colors from the intermediate transfer body is improved. Therefore, these toners are more reliably peeled off from the intermediate transfer member and secondarily transferred to the transfer material without causing transfer residue. As a result, the secondary transfer efficiency is effectively improved, and good secondary transfer characteristics of the toner can be obtained.

In addition, the toner other than the toner facing the intermediate transfer member has a relatively small amount of free external additive between them, so that the adhesion is relatively large and the toner packing property is improved.
As a result, the electrostatic force of the toner increases and the transfer force increases.

Particularly, in the third aspect of the invention, the external additive release rates of the toners of a plurality of colors are defined by the external additive release rates of the toners supplied to the corresponding developing devices. As a result, the external additive release rates of the toners of a plurality of colors can be set more easily. In the invention of claim 4, yellow, magenta, cyan, and black toners are used as the toners of a plurality of colors, respectively, and the secondary transfer efficiency of the toners of these four colors is improved. A full color image is obtained.

Further, in the invention of claim 5, 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.

Moreover, since the amount of the synchronous external additive for each color is set to be the same or substantially the same for each color, the reverse transfer toner from the intermediate transfer member to the image carrier is reduced, so that other colors can be used. It is possible to prevent reverse transfer of toners of different colors to the image carrier. Further, by applying a constant transfer bias during the secondary transfer, the toner is easily moved from the intermediate transfer member to the transfer material, the secondary transfer efficiency is improved, and the transferability in the secondary transfer is improved. .

[0024]

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 toner image forming method, and includes an exposure device 2 for forming an electrostatic latent image, and 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 8a is provided. The toner image forming devices 3 _Y , 3 _M , 3 _C and 3 _BK for the respective colors are arranged in tandem in this order from the upstream side in the moving direction of the intermediate transfer member 4.

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_BKIt has and.

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 of each color 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 member 4 on which the four color toners are superposed in this manner 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 manner 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 intermediate transfer member 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
Number average molecular weight with a single molecular weight distribution curve
(Mn) 2000 to 5000 and weight average molecular weight (M
w) formed from 6000 to 20000 toners
It

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 Of the external additive 1 in the toner 13 _Y of yellow (Y), which is the toner facing the intermediate transfer body, in a state where the toner is overlapped and primarily transferred to the intermediate transfer body 4.
Toners of other colors having a free rate of external additive of 5 _Y ′ 13 _M , 13 _C , 1
It is set so as to be larger than the external additive liberation rate of the free external additive 15 _M ′, 15 _C ′, 15 _BK ′ in 3 _BK and to be the maximum. The yellow (Y) toner is most positioned on the fixing surface side of the heating roller 8a in the state of being secondarily transferred to the transfer material 2.

The external additive release rates of the toners 13 _Y , 13 _M , 13 _C , and 13 _BK of the respective colors are most appropriately determined for the toners primarily transferred to the intermediate transfer member 4 during the primary transfer,
Toners 13 _Y , 13 _M , 13 _C , 13 _BK on the intermediate transfer member 4
Since it is relatively difficult to obtain the external additive release rate of the toner 13 supplied to the developing devices 11 _Y , 11 _M , 11 _C , and 11 _BK ,
By determining the external additive release rates of _Y , 13 _M , 13 _C , and 13 _BK , these external additive release rates can be more easily determined.

Further, the four color toners 13 _Y , 13 _M , 13 _C and 13 _BK used in the color image forming apparatus 1 of this example have the same amount of mother particles 14 _Y , 14 _M , among these colors. 14 _C , 1
4 _BK Synchronous external additive 15 _Y ″, 15 _M ″, 15 _C ″, 15
The amount identical or nearly identical _BK ", i.e., the slope of the synchronous line will be described later (synchronization distribution graph) is set to the same or substantially the same. Therefore, the outside of the yellow toner 13 _Y is an intermediate transfer member facing the toner by addition treatment time is shorter than the toner of the other colors, the maximum relative external additive liberation ratio of the yellow toner 13 _Y is the external additive liberation ratio of the other color toner 13 _M, 13 _C, 13 _BK Is set to.

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).

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 will be 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 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 pulverizing method and a polymerizing method (hereinafter, the former is a pulverizing toner and the latter is a polymerizing 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, a known charge adjusting agent 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.

The pulverized toner of the present invention may be spheroidized for the purpose of improving transfer efficiency. 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.

As the polymerization toner, there are 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 releasing agent are further dispersed in water if necessary, and a polymerization initiator, an emulsifier (surfactant) and the like are polymerized, and then a colorant is added in the aggregation process. 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, and examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene and 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.

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, the toner mother particles 14 _Y , 14 _M , and
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 1 which is a toner facing the intermediate transfer member
The external additive free ratio of the free external additive 15 _Y ′ in 3 _Y is the free external additive 1 in the toners 13 _M , 13 _C , and 13 _BK of other colors.
Since the external additive release rate of 5 _M ′, 15 _C ′, 15 _BK ′ is set to be maximum and maximum, it exists between the yellow (Y) toner 13 _{Y and} the intermediate transfer member 4. A relatively large amount of free external additive 15 _Y ′ can be used. By this free external additive 15 _Y ′, the intermediate transfer member 4 and the toners 13 _Y , 13 _M , 13 _C , 13 _BK
The adhesive force between the toner and the toner can be reduced, and the releasability of these toners 13 _Y , 13 _M , 13 _C , and 13 _BK from the intermediate transfer member 4 can be improved. Therefore, these toners 13 _Y , 13 _M , 13 _C , 1
3 _BK is more surely peeled off from the intermediate transfer member 4 to transfer material 6
It can be secondarily transferred to. This allows toner 1
The secondary transfer efficiency of 3 _Y , 13 _M , 13 _C , 13 _BK can be effectively improved, and good secondary transfer characteristics of the toners 13 _Y , 13 _M , 13 _C , 13 _BK can be obtained.

Further, the free external additives 15 _M ′, 15 _C ′, 15 _BK ′ are relatively present between the toners 13 _M , 13 _C and 13 _BK of other colors other than the yellow (Y) toner 13 _Y. Since the amount is small, the adhesion of these toners 13 _M , 13 _C , and 13 _BK can be made relatively large, and the toner packing property can be improved.

By the way, by maximizing the external additive release rate of the toner 13 _Y of yellow (Y), which is the toner facing the intermediate transfer member, the amount of the free external additive 15 _Y ′ of this toner 13 _Y increases. As described above, the four color toners 13 _Y , 13 _M , 13 _C ,
The same amount of mother particles 14 _Y , 14 _M , 14 _C , 1 among 13 _BK
4 _BK Synchronous external additive 15 _Y ″, 15 _M ″, 15 _C ″, 15
_Since the amount of _BK ″ is set to be the same or almost the same, the external additive 15 _Y ″ of the toner 13 _Y of yellow (Y) is added to the mother particles 14 _{Y as in the case of} the other toners 13 _M , 13 _C and 13 _BK. It is needless to say that the toner 13 _Y has the toner characteristics improved by the external additive 15 _Y ″ by uniformly uniformly coating the toner 13 _Y , and high image quality can be obtained.

Further, 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 units 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 the respective colors
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.

Moreover, the synchronous external additive 15 for each color_Y″, 15
_M″, 15_C″, 15_BK″ Amount is the same or
By setting almost the same, each image carrier from the intermediate transfer body 4
Body 9 _Y, 9_M, 9_C, 9_BKTo reduce the reverse transfer toner to
And the image carrier 9 of another color_Y, 9_M, 9_C, 9_BKTo different colors
The reverse transfer of the toner can be prevented. Also, during secondary transfer
A constant transfer bias is applied to the
Secondary transfer by facilitating the transfer of toner to the transfer material 6.
Efficiency can be improved and good transferability in secondary transfer can be obtained.
be able to.

The order of arranging the toner image forming devices 3 _Y , 3 _M and 3 _C for the respective colors of yellow (Y), magenta (M), cyan (C) and black (BK) is in any order. Can also be set. In that case, the toner 13 of the color of the toner image forming apparatus located at the uppermost stream in the moving direction of the intermediate transfer body 4,
That is, the toner 13 of the color first transferred to the intermediate transfer member 4
The amount of the free external additive 15 'of the toner 13 of the other color is larger than the amount of the free external additive 15' of the toner 13 of the other color (that is, the external additive of the color toner 13 first transferred to the intermediate transfer member 4 is released). The ratio is set to be larger than the external additive liberation ratio of the toner 13 of another color).

Further, the color image forming apparatus 1 of the present invention is
As shown in FIG. 5, the image carrier 9 is not provided for each color, but one image carrier (photosensitive drum) 9 common to each color is provided, and one image carrier (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. Needless to say, the color image forming apparatus 1 of this example also employs the secondary transfer type color image forming apparatus 1 including the intermediate transfer member 4.

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 can be any order. Although it can be set, the amount of the free external additive 15 'of the toner 13 of the color first transferred to the intermediate transfer member 4 is set to the amount of the free external additive 1 of the toner 13 of another color, as in the above-described example.
5'is the maximum (that is, the external additive release rate of the toner 13 of the color first transferred to the intermediate transfer member 4 is made larger than the external additive release rate of the toner 13 of the other color). Is set. Other configurations and other effects of the color image forming apparatus 1 of this example 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. These figures shown in FIGS. 6 and 7
Even in the color image forming apparatus 1, the intermediate transfer is performed although not shown.
It goes without saying that the body 4 is provided. Of these examples
The operational effects of the color image forming apparatus 1 are substantially the same as those of the above-described examples.
Is the same as

Next, an embodiment of the color image forming apparatus 1 of this example will be described. An experiment of the secondary transfer characteristics of the toner was conducted on two examples belonging to the present invention and two comparative examples not belonging to the present invention. The toner 13 used in this experiment has a molecular weight distribution curve in which the toner mother particles have one peak for each color, and the number average molecular weight (M
n) 2000 to 5000 and weight average molecular weight (Mw)
The toner is 6000 to 20000.

The toner of the example was manufactured as follows. That is, for the first layer (opposite the surface of the intermediate transfer member) 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)
It was charged into a Henschel mixer (20 liters) in a proportion of 1.0 part by weight, and external addition treatment in 1 minute treatment time at a rotation speed of 2850Rpm, was yellow toner 13 _Y Examples.

For the magenta toner 13 _M , cyan toner 13 _C and black toner 13 _BK of the second to fourth layers (paper surface side), the respective toner base particles 10 are used.
0 parts by weight of 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 n
m) at a ratio of 1.0 part by weight to a Henschel mixer (20
Liter) and externally added at a rotation speed of 2850 rpm for a processing time of 3 minutes.
_M , cyan toner 13 _C and black toner 13 _BK .

Further, the toner of the example is manufactured as follows. That is, the yellow toner 13 _Y and the magenta toner 1 of the first layer (opposite the surface of the intermediate transfer member) and the second layer
With respect to 3 _M , silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area 141 m ² / g, volume resistivity 10 ¹⁵
Ω · cm, average particle size of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a ratio of 1.0 parts by weight, and externally added at a rotation speed of 2850 rpm for a processing time of 1 minute. The yellow toner 13 _Y and the magenta toner 13 _M were used.

Further, for the cyan toner 13 _C and the black toner 13 _BK of the third and fourth layers (paper surface side), with respect to 100 parts by weight of each toner mother particle,
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 1.0 parts by weight,
External addition was performed at a rotation speed of 2850 rpm for a processing time of 3 minutes to obtain cyan toner 13 _C and black toner 13 _BK of the example.

On the other hand, the toner of the comparative example was manufactured as follows. That is, for the one-layer (facing the fixing surface), the three-layer and four-layer yellow toner 13 _Y , the cyan toner 13 _C, and the black toner 13 _BK , the toner base particles 10 are used.
0 parts by weight of 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 n
m) at a ratio of 1.0 part by weight to a Henschel mixer (20
Liter) and externally added at a rotation speed of 2850 rpm for a processing time of 3 minutes.
_{Y 2} , cyan toner 13 _C, and black toner 13 _BK were used.

For the second layer of magenta toner 13 _M , 100 parts by weight of the magenta toner mother particles were treated with hexamethyldisilazane to obtain silica fine particles (BET specific surface area 141 m ² / g, volume resistance). Rate 10 ¹⁵ Ω · cm, average particle size of primary particles 12 nm) 1.
Henschel mixer (20 liters) at a ratio of 0 parts by weight
It was placed in, and external addition treatment in 1 minute treatment time at a rotation speed of 2850Rpm, and magenta toner 13 _M of comparative examples.

Further, the toner of the comparative example was manufactured as follows. That is, for each of the single-layer (facing the fixing surface), double-layer, and fourth-layer yellow toner 13 _Y , magenta toner 13 _M, and black toner 13 _BK , each toner base particle 1
Silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area of 141 m ² / g,
Volume resistivity 10 ¹⁵ Ω · cm, average particle diameter of primary particles 12 n
m) at a ratio of 1.0 part by weight to a Henschel mixer (20
Liter) and externally added at a rotation speed of 2850 rpm for a processing time of 3 minutes.
_Y , magenta toner 13 _M, and black toner 13 _BK were used.

For the cyan toner 13 _C of the second layer, 100 parts by weight of the cyan toner mother particles were treated with hexamethyldisilazane to obtain fine silica particles (BET specific surface area of 141 m ² / g, volume resistance). Rate 10
¹⁵ Ω · cm, average particle diameter of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a ratio of 1.0 parts by weight, and externally added at a rotation speed of 2850 rpm for a processing time of 1 minute. of the magenta toner 13 _M.

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 external additive release rate and the experimental results of the toners of each color in Examples and Comparative Examples.

[0079]

[Table 1]

In Table 1, the first layer (intermediate transfer member side) toner (toner facing the intermediate transfer member) is yellow (Y) toner 13 _Y , and the second layer toner is magenta (M) toner 13 _M. And the third layer toner is cyan (C) toner 13 _C , and the fourth layer (paper side)
Toner is black (BK) toner _13BK . It should be noted that the first to fourth layers represent layers of toner of colors sequentially located from the top in FIGS. 3B and 3C.

As shown in Table 1, in the examples, the external additive release rate of the first layer yellow toner 13 _Y is 0.26% and the external additive release rate of the second layer magenta toner 13 _M is 0.2%. 15
%, The external additive release rate of the cyan toner 13 _{C in} the third layer is 0.1
The external additive release rate of the black toner _13BK of the fourth layer is 5% and the amount of the external additive is 0.18%. In the example, the external additive release rate of the first layer yellow toner 13 _Y is 0.26%, the external additive release rate of the second layer magenta toner 13 _M is 0.21%, and the third layer cyan is Toner 13 _{C has} an external additive release rate of 0.15%, and fourth layer black toner 13 _{BK has} an external additive release rate of 0.18%.
%.

On the other hand, in the comparative example, the external additive release rate of the first layer yellow toner 13 _Y is 0.15%, the external additive release rate of the second layer magenta toner 13 _M is 0.21%, and the third layer The cyan toner 13 _C of the eye has an external additive release rate of 0.15%, and the black toner 13 _BK of the fourth layer has an external additive release rate of 0.18%. Further, in the comparative example, the first-layer yellow toner 13
The external additive release rate of _Y is 0.15%, the external additive release rate of the second layer magenta toner 13 _M is 0.15%, and the external additive release rate of the third layer cyan toner 13 _C is 0.15%. 21%, the external additive release rate of the black toner _13BK of the fourth layer is 0.18%.

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. Agent 15 _Y , 1
The maximum amount of 5 _M , 15 _C , 15 _BK adhering to the mother particles 14 _Y , 14 _M , 14 _C , 14 _BK was measured, and the free external additive 15 _Y ′,
The maximum amount of external additives released of 15 _M ′, 15 _C ′, 15 _BK ′ is measured, and the total amount of external additives 15 _Y , 15 _M , 15 _C , 15 _BK (maximum attached amount + maximum external additive released amount) Free external additive for 15 _Y ′, 1
It was determined by calculating the percentage of 5 _M ', 15 _C ', 15 _BK '.

Further, as shown in Table 1, as a result of the experiment, the secondary transfer efficiency was 98.1% in Example and 92.3 in Example.
%, The comparative examples were 81.7% and the comparative examples were 75.8%. As is clear from the results of this experiment, the secondary transfer efficiency is comparatively high in Examples and Examples belonging to the present invention, and the secondary transfer efficiency is comparatively low in Comparative Examples and Comparative Example not belonging to the present invention. It was found that the next transfer can be performed better.

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 2 shows the obtained results of the slopes of the synchronization straight lines (synchronization distribution graphs) of the toners of the respective colors and the measurement results of the charge amount in Examples and Comparative Examples.

[0086]

[Table 2]

As shown in Table 2, in the example, the synchronization line of the yellow (Y) toner 13 _Y (synchronization distribution graph)
Has a slope of 0.520, the slope of the sync line (sync distribution graph) of the toner 13 _M of magenta (M) is 0.515, and the slope of the sync line (sync distribution graph) of the toner 13 _C of cyan (C) is 0. .513, a slope of the black synchronous linear toner 13 _BK of (BK) (synchronous distribution chart) is 0.522, four colors of inclination is approximately the same. In the comparative example, the inclination of the synchronization line (synchronization distribution graph) of the yellow (Y) toner 13 _Y is 0.685, and the inclination of the synchronization line (synchronization distribution graph) of the magenta (M) toner 13 _M is 0. 48
9, the gradient of the synchronization line (synchronization distribution graph) of the toner 13 _C of cyan (C) is 0.662, and the inclination of the synchronization line (synchronization distribution graph) of the toner 13 _BK of black (BK) is 0.7
12, there are considerable variations in the inclinations of the four colors.

As a result of the measurement of the charge amount, in the embodiment, the charge amount of the yellow (Y) toner 13 _Y is -17.8 μC /
g, the charge amount of magenta (M) toner 13 _M is -18.3
μC / g, Cyan (C) toner 13 _{C has} a charge amount of -1
The toner 13 _BK of 8.2 μC / g and black (BK) had a charge amount of -18.6 μC / g, and the charge amounts of the four colors were almost the same. In the comparative example, the toner amount of the yellow (Y) toner 13 _Y is −21.3 μC / g, the toner amount of the magenta (M) toner 13 _M is −15.4 μC / g, and the cyan (C) toner is The charge amount of 13 _C is −20.0 μC /
g, black (BK) toner 13 _{BK has} a charge amount of -2
It was 5.8 μC / g, and there were considerable variations in the charge amounts of the four colors. As is clear from the measurement results, it was found that the charging characteristics were substantially uniform in the examples belonging to the present invention, and the charging characteristics were different for each color in the comparative examples not belonging to the present invention.

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 can be applied to any color image forming apparatus as long as it forms a color image using toners of two or more colors for secondary transfer.

[0090]

As is apparent from the above description, according to the color image forming apparatus of the present invention, the external additive of the free external additive liberated from the mother particles of the intermediate transfer member facing toner facing the intermediate transfer member. The liberation rate is set to 0.2% or more and the liberation rate of the external additive of the toner of other colors is set smaller than this, or the liberation liberated from the mother particles of the toner facing the intermediate transfer body facing the intermediate transfer body. Since the external additive release rate of the external additive is set to be higher than the external additive release rate of the toner of the other color, the free external addition that is relatively large between the intermediate transfer body and the intermediate transfer body of the toner facing the intermediate transfer body. The agent makes it possible to reduce the adhesive force between the intermediate transfer member and the toners of a plurality of colors, and improve the releasability of the toners of a plurality of colors from the intermediate transfer member. Therefore, these toners can be more surely peeled from the intermediate transfer member and secondary-transferred onto the transfer material, so that the secondary transfer efficiency can be effectively improved and good secondary transfer characteristics of the toner can be obtained.

Further, since the amount of the free external additive can be relatively small among the toners other than the toner facing the intermediate transfer member, the adhesion can be increased and the toner packing property can be improved. As a result, the electrostatic force of the toner can be increased and the transfer force can be increased.

In particular, according to the second aspect of the invention, the external additive release rates of the toners of a plurality of colors are defined by the external additive release rates 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.

Moreover, since the amount of the synchronous external additive for each color is set to be the same or substantially the same for each color, the reverse transfer toner from the intermediate transfer member to the image carrier can be reduced, and therefore the amount of the other color toner can be reduced. Reverse transfer of toners of different colors onto the image carrier can be prevented. In addition, a constant transfer bias is applied during secondary transfer to facilitate transfer of toner from the intermediate transfer member to the transfer material, thereby improving secondary transfer efficiency and ensuring good transferability in secondary transfer. Obtainable.

[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 and partially 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.

[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 15/16 G03G 9/08 361 (72) Inventor ▲ Hidehiro Takano 3-3 Yamato, Suwa City, Nagano Prefecture No. 5 Seiko-Epson Corporation F-term (reference) 2H005 AA08 AA21 CB07 CB08 CB10 CB13 EA10 2H200 GA11 GA12 GA23 GA31 GA47 GA49 GB12 GB22 GB25 HA02 HB12 JA02 JC03 2H300 EB02 EJ02 EJ02 EJ02 EJ02 EJ02 EC05 EC05 EC05 EC05 EC09 FF05 TT02

Claims (5)

[Claims] 1. A plurality of color toners, each of which is composed of a large number of mother particles and a large number of particles of an external additive adhered to the respective mother particles, is superposed on the intermediate transfer member and primary-transferred, and the intermediate transfer member is also transferred. Secondary transfer the above toner to the transfer material,
In a color image forming apparatus that forms a color image by fixing the toner on the transfer material, among the toners of the plurality of colors attached to the intermediate transfer member,
An external additive of a free external additive that is located closest to the intermediate transfer body and is a toner that faces the intermediate transfer body and that is a toner that faces the intermediate transfer body and that is free from the mother particles of the toner that faces the intermediate transfer body. A color image forming apparatus characterized in that the agent release rate is 0.2% or more, and the external additive release rate of toners of other colors is set smaller than this. 2. A toner of a plurality of colors, each of which is composed of a large number of mother particles and a large number of particles of an external additive adhered to these mother particles, is superposed on the intermediate transfer member and primary-transferred, and the intermediate transfer member is also transferred. Secondary transfer the above toner to the transfer material,
In a color image forming apparatus that forms a color image by fixing the toner on the transfer material, among the toners of the plurality of colors attached to the intermediate transfer member,
External additive of a free external additive which is located at the side closest to the intermediate transfer member and which is an additive of the toner facing the intermediate transfer member of a color facing the intermediate transfer member, and which is liberated from the mother particles of the toner facing the intermediate transfer member. A color image forming apparatus, wherein the agent release rate is set to be higher than the external additive release rate of toners of other colors. 3. The external additive release rate of the toners of the plurality of colors is the external additive release rate of the toners supplied to the corresponding developing devices, respectively. Color image forming apparatus. 4. The toners of a plurality of colors are yellow, magenta, cyan and black toners, respectively, and the intermediate transfer member facing toner is any one of these toners. 3. The color image forming apparatus according to any one of 3 above. 5. 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.