JP2001005220A - Color toner and color electrophotographic method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the electrostatic chargeability of each of yellow, magenta, cyan and black toners due to the surface state and the surface state difference among the color toners due to a way of cracking in comminution and to stably output a high grade color image by specifying the difference between the maximum and minimum coefficients of dynamic friction of each of the color toners. SOLUTION: When the coefficients of dynamic friction of yellow, magenta, cyan and black toners each consisting essentially of a bonding resin, a colorant and an additive are represented by YF, MF, CF and BF, respectively, the relation of the expression max(YF, MF, CF, BF)-min(YF, MF, CF, BF)<=0.2 [where max() shows the maximum value in () and min () shows the minimum value in ()] is satisfied. The expression shows the difference in the coefficient of dynamic friction among the color toners. When the difference increases, the toners are made different from one another in dynamic separability from a photoreceptor or an interim transfer body, have different transfer behaviors in a transfer part and cannot attain accurate color reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color toner used in a copying machine, a printer and a facsimile, and a color electrophotographic method.

[0002]

2. Description of the Related Art A printing process of an electrophotographic copying machine and a printer will be described. First, an image carrier (hereinafter, referred to as a photoconductor) is charged for image formation. As a charging method, a conventional corona charger is used. In recent years, a contact-type charging method in which a conductive roller is directly pressed against a photosensitive member with the aim of reducing the amount of generated ozone is used. There is a method of uniformly charging the surface. After charging the photoreceptor, in the case of a copying machine, light is radiated to a copy original and reflected light is radiated to the photoreceptor through a lens system. Alternatively, in the case of a printer, an image signal is sent to a light emitting diode or a laser diode as an exposure light source, and a latent image is formed on a photoconductor by turning on and off light. When a latent image (high or low surface potential) is formed on the photoreceptor, the photoreceptor is visualized by a toner (having a diameter of about 5 μm to 15 μm) which is a pre-charged colored powder. The toner adheres to the surface of the photoconductor in accordance with the level of the surface potential of the photoconductor, and is electrically transferred to copy paper. That is, the toner is positively or negatively charged in advance, and is electrically attracted from the back surface of the copy sheet by applying a charge having a polarity opposite to the polarity of the toner. As a transfer method, a method using a conventionally used corona discharger,
In recent years, a transfer method in which a conductive roller is directly pressed against a photoreceptor has been put to practical use in order to reduce the amount of generated ozone.

At the time of transfer, not all of the toner on the photoreceptor is transferred to the copy paper, but a part of the toner remains on the photoreceptor. This residual toner is scraped off by a cleaning blade or the like in the cleaning unit and becomes waste toner. Then, in the fixing process, the toner transferred to the copy paper is
Fixed on paper.

As is well known, toner for electrostatic charge development used in an electrophotographic method generally comprises a resin component, a coloring component comprising a pigment or a dye, a plasticizer, a charge controlling agent, and if necessary, a magnetic material. , A release agent and the like. As the resin component, a natural or synthetic resin is used alone or in a suitable mixture.

[0005] The above additives are preliminarily mixed in an appropriate ratio, heated and kneaded by heat melting, finely pulverized by an air-flow type impact plate system or the like, and classified into fine powder to complete a toner matrix. Thereafter, an external additive is externally added to the toner matrix to complete the toner.

[0006] In one-component development, a two-component developer is obtained by mixing a toner and a carrier composed of magnetic particles.

In a color copying machine, a photoreceptor is charged by corona discharge using a charging charger, and then a latent image of each color is irradiated as a light signal on the photoreceptor to form an electrostatic latent image, and a first color, for example, The latent image is developed by developing with a yellow toner. Thereafter, a transfer material charged to a polarity opposite to that of the yellow toner is brought into contact with the photoconductor, and the yellow toner image formed on the photoconductor is transferred. The photoreceptor is cleaned after removing the toner remaining at the time of transfer, and is then discharged, thereby completing the development and transfer of the first color toner.

Thereafter, the same operation as that for the yellow toner is repeated for toners such as magenta and cyan, and a color image is formed by superimposing toner images of each color on a transfer material. Then, these superimposed toner images are transferred to a transfer paper charged to a polarity opposite to that of the toner, and then fixed to complete the copying.

In this color image forming method, a toner image of each color is sequentially formed on a single photoreceptor, and a transfer material wound around a transfer drum is rotated to repeatedly face the photoreceptor, where the toner is sequentially formed. A transfer drum system in which toner images of each color are transferred in a superimposed manner, and a plurality of image forming units are arranged side by side, and each toner image of each color is sequentially passed through a transfer material conveyed by a belt through each image forming unit. A continuous superimposition method in which a color image is transferred and superimposed is generally used.

A color image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 1-25982 is one using the above-mentioned transfer drum system. FIG. 3 shows an outline of the overall configuration of this conventional example, and its configuration and operation will be briefly described below. In FIG. 5, reference numeral 501 denotes a photosensitive member, and a charger 50 is opposed thereto.
2, a developing unit 503, a transfer drum 504, a cleaner 5
05 is provided. The developing unit 503 includes a Y developing device 506 for forming a yellow toner image, and a magenta M
Developing unit 507, cyan C developing unit 508, black Bk
The entire developing unit group rotates, and each developing unit sequentially faces the photoconductor 501 to be in a developable state. During operation, the transfer drum 504 and the photoconductor 501 rotate at a constant speed in the direction of the arrow while facing each other.

When the image forming operation is started, the photosensitive member 501 rotates in the direction of the arrow, and its surface is uniformly charged by the charger 502. Thereafter, the surface of the photoreceptor is irradiated with a laser beam 510 modulated by a signal for forming a first yellow image, thereby forming a latent image. Next, this latent image is first applied to the Y developing device 5 facing the photoconductor 501.
06 to form a yellow toner image.
The yellow toner image formed on the photoconductor is transferred to transfer drum 5
By the time the sheet moves to the position opposing to the sheet 04, one sheet of the transfer material sent from the sheet feeding unit 511 is already wound around the outer periphery of the transfer drum 504 with the leading end caught by the claw 512. The timing is set so that the yellow toner image on the photoreceptor meets the predetermined position on the sheet.

After the yellow toner image on the photoreceptor is transferred to the sheet by the operation of the transfer charger 513, the surface of the photoreceptor is cleaned by the cleaner 505 to prepare the next color image formation. Subsequently, magenta, cyan, and black toner images are formed in the same manner. At that time, the developing unit 503 causes the developing units 506 to 509 used in accordance with the colors to face the photoreceptor so as to be in a developable state. The diameter of the transfer drum 504 is large enough to allow the longest sheet to be wound and to replace the developing device between the images of each color.

Laser beam 510 for image formation of each color
Is performed at a timing such that the toner image of each color on the photoconductor and the toner image already transferred onto the sheet on the transfer drum are aligned and opposed as the rotation is performed. Thus, the four color toner images are transferred to the transfer drum 5.
The image is transferred onto the sheet on the sheet 04 to form a color image on the sheet. After the toner images of all colors have been transferred, the paper is peeled from the transfer drum 504 by the peeling nails 514,
The toner image is fixed by the fixing device 516 via the transport unit 515, and is discharged out of the apparatus.

On the other hand, as an example of a color image forming apparatus using the continuous transfer method, there is Japanese Patent Application Laid-Open No. 1-250970. In this conventional example, four image forming stations each including a photoreceptor, an optical scanning means, etc. are arranged for forming images of four colors, and the paper conveyed to the belt passes under the respective photoreceptors and the color is transferred. The toner images are superimposed. Further, as another method of forming a color image by superimposing toner images of different colors on a transfer material, each color toner image sequentially formed on a photoreceptor is temporarily superimposed on an intermediate transfer material, and finally, the intermediate image is formed. Japanese Patent Application Laid-Open No. H2-212867 discloses a method of collectively transferring a toner image on a transfer material to transfer paper.

[0015]

The demand for color documents in offices has recently been increasing with the demand for color documents in offices. However, assuming use in offices, high quality images are of course required. It is also required that the OHP light transmissivity is high, the size is small, the running cost is low, the maintenance is easy, and the user can perform the operation. Also, a high monochrome output speed is necessary for a color output device in order to replace a conventional monochrome output device.

The electrophotographic printing system is currently the mainstream as a monochrome output device for office use because of its high image quality and high output speed, and it is expected that its characteristics can be utilized even in color.

Among them, toner can be said to be a key part that greatly affects the developing property and the fixing property and determines the performance of electrophotographic equipment.

Since a full-color image is reproduced using four color toners, high-quality color reproduction cannot be performed if the developing property and the transfer property are different for each toner. Until now, the study of the chargeability of the colorant among the characteristics of the toner has been conducted only on the influence on the chargeability in the black toner as disclosed in JP-A-63-128364. There is no description regarding the charging characteristics between the toner colors.

In the kneading step, the colorant is micro-dispersed in the binder resin, and this dispersion state affects not only the color developing property of the toner, but also the charging property and how the toner breaks during the pulverizing step. When the dispersibility is deteriorated, uneven distribution or release of the colorant in the resin occurs, and the ground fog increases due to the increase of the oppositely charged particles. In addition, the release of the coloring agent causes a problem that the surface state of the toner is changed and that the photoconductor and the developing sleeve are contaminated.

In particular, when the molecular weight of the high molecular weight component is increased or the crosslinking component is introduced to improve the hot offset resistance, the melt viscosity of the binder resin is reduced or the molecular weight is reduced to increase the meltability of the toner. When a resin is used, poor dispersion of the colorant is more likely to occur.

Further, the color coloring agent not only has its own charging characteristics depending on the color and type, but also has a different dispersion state in the binder resin due to its shape, particle size, surface treatment and the like. For this reason, the surface state due to the toner charge amount and how it is broken differs for each color of the color toner.

When a color image is output using a toner having different chargeability and surface condition for each color, a high-quality color image cannot be obtained because the developability and the transferability are different.

Further, a resin having a low surface energy is coated as a measure against so-called spent property in which the low melting point component of the toner adheres to the carrier surface, but this changes the slipperiness with the toner and conversely deteriorates the rising property of charging. This may lead to an increase in land fog.

Further, as will be described later, the electrophotographic method of the present invention employs an intermediate transfer member.

In the transfer drum system, a transfer drum is used to align and overlap toner images of different colors, the transfer drum is rotated at the same speed with respect to the photosensitive member, and the timing of the leading edge of the image is adjusted. Thus, the mutual positions of the respective color toner images when forming a color image are matched. However, in the above configuration, since the paper must be wound around the transfer drum, the diameter of the transfer drum needs to be a certain size or more, and the structure is extremely complicated and high accuracy is required. But it was large and expensive. In addition, strong paper such as postcards and cardboard,
It could not be used because it could not be wound around the transfer drum.

On the other hand, the continuous transfer system has an image forming position corresponding to the number of colors, and it is only necessary to successively pass the paper through the image forming position. In this case, a plurality of latent image forming means such as a laser optical system for forming a latent image on a photoreceptor are required in accordance with the number of colors, and the structure is very complicated and expensive. Furthermore,
Since there are a plurality of image forming positions, it is difficult to obtain high image quality stably because the relative displacement of the image forming units of each color, the eccentricity of the rotation axis, and the displacement of the parallelism of each unit directly affect the color misregistration. there were. In particular, it is necessary to accurately perform positioning between the colors of the latent image by the latent image forming means.
As described in Japanese Patent Application Laid-Open Publication No. H11-209, there has been a problem that an image exposure system as a latent image forming means requires a considerable device and a complicated configuration.

Further, JP-A-2-2-2 using an intermediate transfer material
In the example of Japanese Patent No. 12867, in order to form toner images of each color on the same photoreceptor, a plurality of developing units must be arranged around a single photoreceptor. And the photosensitive member has a belt shape that is difficult to handle. Also, if each developing device is replaced during maintenance, matching adjustment with the characteristics of the photoconductor is required, and when replacing the photoconductor, it is necessary to adjust the position with each developing device. Maintenance of the body was also difficult.

However, the intermediate transfer method does not require a complicated optical system and can be used for rigid paper such as postcards and thick paper. The use of an intermediate transfer belt is flexible, so the transfer drum method, continuous transfer There is an advantage that the size of the device itself can be reduced as compared with the system.

It is ideal that all of the toner is transferred at the time of transfer, but some transfer residue remains. The so-called transfer efficiency is not 100%, but is generally about 75 to 90%. The transfer residual toner is scraped off by a cleaning blade or the like in a photoconductor cleaning process, and becomes waste toner.

However, in the configuration using the intermediate transfer member,
The toner undergoes at least two or more transfer steps from the photoreceptor to the intermediate transfer body, and further from the intermediate transfer body to the transfer paper.
Transfer efficiency, the transfer efficiency is reduced to 72% by two transfers. Further, in the case of a transfer efficiency of 75% in one transfer, 56% or about half of the toner becomes waste toner, so that the cost of the toner is increased and the volume of the waste toner box must be increased. In this case, the size of the device cannot be reduced. The decrease in transfer efficiency is considered to be due to ground fogging of the opposite polarity due to poor dispersion and transfer omission.
In the case of color toner, if the transfer efficiency differs for each toner, the difference is amplified and accurate color reproduction cannot be performed.

Further, in color development, the toner image of four colors is superimposed on the intermediate transfer member, so that the toner layer becomes thick, and a pressure difference is easily generated between the toner image having no or thin toner layer. For this reason, the "hollow-out" phenomenon in which a part of the image is not transferred and becomes a hole due to the aggregation effect of the toner is likely to occur. Furthermore, if a material having a high toner releasing effect is used for the intermediate transfer member in order to surely perform cleaning when the transfer paper is jammed, hollow holes will be noticeable and image quality will be significantly reduced. Furthermore, edge development is performed for characters and lines, and the amount of toner is increased, and toner particles are aggregated by pressurization, so that hollow holes become more noticeable.
In particular, it appears more remarkably in a high-humidity and high-temperature environment.

Further, when a wide range of developing process speeds are to be supported at the time of monochrome output, it is required that even if the developing process speed is changed, the black toner has high fixability and anti-offset property, and that the charge amount and the dynamic friction coefficient change little. Is done. When the developing process speed is increased, if the rise of the toner charge amount is slow, the toner charge amount is significantly reduced in continuous printing, and image formation cannot be performed.

As will be described later, in the electrophotographic method using the toner according to the present invention, an image forming unit group in which a plurality of movable image forming units for forming toner images of different colors are arranged in an annular shape. And the entire image forming unit rotates. Further, an image forming unit,
It is possible to replace each intermediate transfer unit, and when the end of its life comes, it is easy to perform maintenance by replacing each unit, and it is possible to obtain the same level of maintenance as an electrophotographic color printer in black and white. Becomes However, since the image forming unit itself revolves, the cleaned waste toner temporarily and repeatedly adheres to the photoconductor, and is repeatedly separated from and adhered to the developing roller. If the rising property of the charge is poor in the early stage of the test, initial fog is induced.

The present invention has been made in view of the above problems, and has a toner charging property caused by a dispersion state of a colorant in a binder resin and a toner surface state after a pulverization step, and a surface state difference caused by a cracking method during toner pulverization. It is an object of the present invention to provide a color toner capable of stably outputting a high-quality color image by suppressing the color toner among the color toners.

It is another object of the present invention to provide a black toner having high fixability and anti-offset property and little change in developing characteristics even when the developing process speed is different.

It is another object of the present invention to provide a color toner which can prevent dropout or scattering at the time of transfer by an electrophotographic method using a conductive elastic roller or an intermediate transfer member and can obtain high transfer efficiency.

[0037]

The first aspect of the color toner according to the present invention is a color toner comprising at least a binder resin, a colorant, and an external additive, and includes a yellow toner, a magenta toner, and a color toner. The dynamic friction coefficients of the cyan toner and the black toner are represented by YF, MF, CF, and KF, respectively.
Wherein the color toner has the relationship of (Equation 1).

The second structure of the color toner according to the present invention is a color toner comprising at least a binder resin, a colorant, and an external additive, and includes a yellow toner, a magenta toner, a cyan toner, and a black toner. When the absolute values of the charge amounts are YQ, MQ, CQ, and KQ, respectively, the color toner has a relationship of (Equation 2).

The third configuration of the color toner according to the present invention is a color toner comprising at least a binder resin, a colorant, and an external additive, and includes a yellow toner, a magenta toner, a cyan toner, and a black toner. When the kinetic friction coefficients are YF, MF, CF, and KF, and the absolute values of the charge amounts are YQ, MQ, CQ, and KQ, respectively, the relations of Expressions 3 and 4 are simultaneously satisfied. Toner.

Further, in the color toner according to any one of the above aspects of the invention, a toner image obtained by visualizing an electrostatic latent image formed on an image carrier is transferred to the image carrier by an endless intermediate transfer member. A primary transfer process of transferring the toner image to the surface of the intermediate transfer member by bringing the surface of the intermediate transfer member into contact with the surface of the intermediate transfer member is repeatedly performed a plurality of times. The method is suitably used in a color electrophotographic method having a transfer system configured to execute a secondary transfer process of collectively transferring the overlap-transferred toner image formed on the transfer material.

The color toner according to any one of the above-mentioned aspects of the present invention is provided with an image carrier each rotating at least and developing means having toners of different colors, and different color toners are provided on the image carrier. A plurality of movable image forming units that form a toner image, an image forming position composed of a single exposure position and a single transfer position,
An image forming unit group in which the plurality of image forming units are arranged in an annular shape, and each of the plurality of image forming units,
A moving unit for rotating the entire image forming unit group to sequentially move to the single image forming position, an exposure unit for generating a signal light, and the rotation center of the image forming unit group substantially at the center of rotation. A mirror for guiding the light of the exposure means to the exposure position, and is preferably used in a color electrophotographic apparatus for forming a color image by transferring toner images of different colors onto a transfer material while superposing and transferring the same. .

Further, in the color toner of the present invention, in any one of the first to third constitutions, the external additive to be added to the toner may be silicon oxide fine powder, titanium oxide fine powder, titanate fine powder, It is preferable that the external additive is made of at least one or more of the zirconia acid-based fine powder.

Further, in the color toner of the present invention, in any one of the first to third constitutions, the binder resin, which is a main component of the toner, has a weight average molecular weight Mw of 10,000 to 300,000 and a weight average molecular weight Mw of The ratio Mw / Mn of the number average molecular weight Mn is 3 to 50, and the ratio M between the Z average molecular weight Mz and the number average molecular weight Mn.
z / Mn is 10 to 800, 1 by Koka type flow tester
/ 2 Outflow temperature is 80-150 ° C, outflow start temperature is 80-
A binder resin which is a polyester resin obtained by polycondensation of a polyvalent carboxylic acid or a lower alkyl ester thereof at 120 ° C. and a polyhydric alcohol is preferred.

Further, in the color toner of the present invention, in any one of the first to third constitutions, the weight average molecular weight Mw of the binder resin as a main component of the toner is 100,000 to 500,000,
Ratio Mw / Mn of weight average molecular weight Mw to number average molecular weight Mn
Styrene (meth) acrylic acid alkyl ester having a ratio of Mz / Mn of 350 to 900, a half-flow temperature of 105 to 145 ° C. in a Koka type flow tester, of 40 to 90, a Z average molecular weight Mz and a number average molecular weight Mn. Binder resins that are copolymers are preferred.

Further, in the color toner of the present invention, in any one of the first to third constitutions, the weight average molecular weight Mw of the binder resin as a main component of the black toner constituting the color toner is from 100,000 to 500,000. The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 40 to 90, and the ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 350.
-900, a styrene (meth) acrylic acid alkyl ester copolymer having a 流出 outflow temperature of 105 to 145 ° C. in a Koka type flow tester, and is mainly used for yellow toner, magenta toner and cyan toner constituting a color toner. The weight average molecular weight Mw of the binder resin as a component is 10,000 to
300,000, ratio M between weight average molecular weight Mw and number average molecular weight Mn
w / Mn is 3 to 50, ratio Mz / Mn of Z average molecular weight Mz to number average molecular weight Mn is 10 to 800, 1/2 outflow temperature by Koka flow tester is 80 to 150 ° C, outflow start temperature is 80 to A binder resin which is a polyester resin obtained by polycondensation of a polyvalent carboxylic acid or a lower alkyl ester thereof at 120 ° C. and a polyhydric alcohol is preferred.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION The color toner of the present invention can suitably use a polyester resin as a binder resin.

The binder resin is composed of a polyester resin obtained by polycondensation of a polycarboxylic acid or a lower alkyl ester thereof with a polyhydric alcohol. Polycarboxylic acids or lower alkyl esters include malonic acid, succinic acid, glutaric acid, adipic acid, aliphatic dibasic acids such as hexahydrophthalic anhydride, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citracone Examples thereof include aliphatic unsaturated dibasic acids such as acids, aromatic dibasic acids such as phthalic anhydride, phthalic acid, terephthalic acid, and isophthalic acid, and methyl esters and ethyl esters thereof. Of these, aromatic dibasic acids such as phthalic acid, terephthalic acid, and isophthalic acid, and lower alkyl esters thereof are preferred.

As the polyhydric alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4
Diols such as butylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, glycerin, trimethylolpropane, trimethylolethane, etc. Triols and mixtures thereof can be exemplified. Among them, neopentyl glycol, totimethylolpropane, bisphenol A ethylene oxide adduct, bisphenol A
Propylene oxide adducts are preferred.

For polymerization, known polycondensation, solution polycondensation and the like can be used. As a result, a good toner can be obtained without impairing the PVC mat resistance and the color of the color material of the color toner.

The ratio of the number of hydroxyl groups to the number of carboxyl groups (OH / COOH) is generally 0.8 to 1.4.
The polyester resin preferably has a hydroxyl value of 6 to 10.
0.

This polyester resin has a weight average molecular weight Mw of 10,000 to 300,000, a ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of 3 to 50, and a ratio Mz of the Z average molecular weight Mz to the number average molecular weight Mn. / Mn is preferably from 10 to 800, a 1/2 outflow temperature (softening point) by a Koka type flow tester is in the range of 80 to 150 ° C, and an outflow start temperature is in the range of 80 to 120 ° C.

The color toner to be fixed to form an image in which four colors overlap with each other has a weight average molecular weight Mw of 10,000 to 18 from the viewpoints of light transmission, anti-offset property, and improvement in colorant dispersibility.
10,000, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn Mw /
Mn is 3 to 20, Z average molecular weight Mz and number average molecular weight Mn
Has a ratio Mz / Mn of 10 to 300 and a softening point of 85 to 120.
° C and the outflow starting temperature are preferably in the range of 80 to 110 ° C. More preferably, the weight average molecular weight Mw is 10,000 to 150,000, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 3 to 16, and the ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 10 ~ 260, softening point is 90 ~
It is preferable that the temperature is 115 ° C and the outflow start temperature is in the range of 85 to 110 ° C. More preferably, the weight average molecular weight M
w is 10,000 to 100,000, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 5 to 12, the ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 14 to 220, and the softening point is 95. To 115 ° C., and the outflow starting temperature is preferably in the range of 85 to 105 ° C.

When used as a monochromatic toner, which is a one-color development, light transmittance and smoothness need not be considered so much.
mm / sec to 250 mm / sec), it is necessary to increase the meltability of the toner-fixed image and to have an appropriate viscoelasticity in order to improve the offset resistance. is there. for that reason,
Weight average molecular weight Mw of 50,000 to 300,000, weight average molecular weight M
The ratio Mw / Mn of w to the number average molecular weight Mn is 5 to 50, and the ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 50.
~ 800, softening point 90 ~ 150 ° C, outflow starting temperature 8
It is preferably in the range of 0 to 120 ° C. More preferably, the weight average molecular weight Mw is 80,000 to 250,000, and the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 7 to 4
5. Ratio Mz / M between Z-average molecular weight Mz and number-average molecular weight Mn
It is preferable that n is 100 to 700, the softening point is 95 to 146 ° C, and the outflow starting temperature is 85 to 115 ° C.
More preferably, the weight average molecular weight Mw is 100,000 to 22.
10,000, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn Mw /
Mn is 9 to 45, Z average molecular weight Mz and number average molecular weight Mn
Has a ratio Mz / Mn of 150 to 600 and a softening point of 100 to 1
It is preferable that the flow start temperature is 42 ° C and the outflow starting temperature is 85 to 110 ° C.

In the present invention, as the binder resin,
Styrene (meth) acrylic acid alkyl ester copolymers can also be suitably used. In the above, "(meth) acryl ..." means "acryl ..." or "methacryl ..." and includes a polymer obtained by copolymerizing at least a styrene monomer.

Specific examples of the styrene monomer include styrene, substituted styrenes such as α-methylstyrene and P-chlorostyrene, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate and dodecyl acrylate. Acrylates such as octyl acrylate, octyl acrylate, isobutyl acrylate, hexyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, isobutyl methacrylate, dodecyl methacrylate, hexyl methacrylate, etc. And methacrylic acid alkyl esters. As a method for producing the polymer, known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used. In the present invention, a polymer obtained by polymerizing such a vinyl monomer is used as a main component of the binder resin, but if necessary, other than a polymer obtained by polymerizing the vinyl monomer. A polymer such as a polyester-based resin, an epoxy-based resin, or a polyurethane-based resin can be contained in the binder resin.

In the present invention, when it is used as a black toner for monochrome development, it is not necessary to consider light transmittance and smoothness very much. For example, in the case of monochrome development, by performing higher-speed development than in the case of color development with a single color of black toner, when both a high-speed monochrome printer and a color printer are used in a single unit, toner develops over a wide range of development process speeds (50 mm / sec. ~ 250mm / se
It is necessary to respond to c). At this time, it is necessary to increase the fixing strength of the toner-fixed image and to have appropriate viscoelasticity in order to improve the offset resistance. In order to increase the penetrating power to paper and improve the offset resistance, it is preferable to specify the composition, glass transition point, and molecular weight of each of the low molecular weight polymer component and the high molecular weight polymer component of the binder resin.

Specifically, as the low molecular weight polymer component,
It contains a styrene polymer having a weight average molecular weight in the range of 2,500 to 20,000, a glass transition point of 50 ° C. or more, and has a weight average molecular weight of 100,000 or more as a high molecular weight polymer component.
The glass transition point is in the range of 50 to 70 ° C, preferably the weight average molecular weight is 120,000 or more and the glass transition point is in the range of 55 to 70 ° C, more preferably the weight average molecular weight is 150,000 or more and the glass transition point is 55 to 65. It is preferable to use one containing a styrene-acrylic copolymer in the range of ° C. The mixing ratio of the low molecular weight polymer component to the high molecular weight polymer component is preferably in the range of 9: 1 to 5: 5. The weight average molecular weight Mw of the entire binder resin is 100,000 to 50
10,000, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn Mw /
Mn is 40 to 90, Z average molecular weight Mz and number average molecular weight M
The ratio Mz / Mn of n is 350 to 900, and the 1/2 outflow temperature (hereinafter, softening point) by the Koka flow tester is 105 to 14
Preferably it is 5 ° C.

Further, the weight average molecular weight Mw is from 120,000 to 4
50,000, ratio Mw between weight average molecular weight Mw and number average molecular weight Mn
/ Mn is 45 to 85, the ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 400 to 800, and the softening point is 110.
It is more preferable that the temperature is 140 ° C. Further, the weight average molecular weight Mw is 120,000 to 350,000, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 55 to 85, and the ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 400.
More preferably, the softening point is 115 to 140 ° C.

Further, in order to further improve the fixing property and the pulverizability at the time of pulverization in the production stage, the binder resin preferably contains 50 to 95% by weight of a styrene component.
In addition, the flow start temperature of the binder resin by the flow tester is
It is good to be in the range of 80 to 120C, preferably in the range of 85 to 110C, and more preferably in the range of 95 to 108C.

To improve the offset resistance and the fixing strength, the toner may contain a vegetable wax. In the present invention, the melting point by the DSC method is 66 to 86.
Vegetable waxes with a temperature of ° C. are preferred. This acts as a fixing improver to improve the fixing strength and to improve the offset resistance. The addition amount is preferably 1 to 20 parts by weight per 100 parts by weight of the binder resin.

As the vegetable wax, carunauba wax having a melting point of 80 to 86 ° C. according to the DSC method and an acid value of 2 to 10, a melting point of 68 to 72 ° C. according to the DSC method, and an acid value of 12 to 20 ° C. Hydrogenated jojoba oil having a melting point of 66-72 ° C by DSC method and an acid value of 3 or less, and a loss on heating at 220 ° C of 2% or less; a melting point of 79-83 ° C by DSC method and an acid value of Is preferably 2 to 13, and one type or a combination of two or more types can be used.

In the present invention, a polyethylene wax may be added to the binder resin. This has the effect of reducing the friction on the image surface. On the image surface with reduced friction, there is an action of releasing external force, and as a result, fixability is improved. Preferred are polyethylene waxes made by a pyrolysis method. The recovery rate after washing with toluene at 25 ° C. for 1 hour is 95% or more. The melting point of the polyethylene wax by the DSC method is 80 to 140 ° C, preferably 90 to 135 ° C, more preferably 95 to 130 ° C.
It is good to be in the range. When the melting point is higher than 140 ° C., the release agent does not melt at the time of fixing, the release agent does not elute at the interface between the fixing hard roller and the toner, and a high-temperature offset tends to occur. When the melting point is 80 ° C. or less, the heat resistance of the toner is reduced, and aggregation and solidification are likely to occur. The wax is generally added in an amount of 0.1 to 20 parts by weight, preferably 1.0 to 15 parts by weight, per 100 parts by weight of the binder resin.

In the present invention, it is more preferable to use a polyethylene wax in combination with a vegetable wax.

Other examples of the release agent include low-molecular-weight polyalkylenes such as low-molecular-weight polypropylene, ethylene bisamide, montan wax, and paraffin wax. One or more of these may be mixed. May be used.

In the present invention, the developing property and the transferring property which are different for each color are made uniform by controlling the charging characteristics and the surface state of the color toner. In the present invention, the surface state of the color toner is quantified by the coefficient of dynamic friction of the toner.

In the present invention, when the dynamic friction coefficients of the yellow toner, magenta toner, cyan toner, and black toner of the color toners are YF, MF, CF, and KF, respectively, it is preferable to satisfy the relationship of (Equation 1).

That is, in the color toner, since different colorants such as pigments and dyes are used for color reproduction of yellow, magenta, cyan and the like as described above, the chargeability and the coefficient of dynamic friction of the toner are affected by the pigments and dyes. The effect is different. Furthermore, when the type and amount of the charge control agent are adjusted in order to reduce the influence of pigments and dyes having different charging properties, the influence on the dynamic friction coefficient becomes larger.

(Equation 1) shows the difference in the dynamic friction coefficient between the color toners. When the difference is large, a difference occurs in the ease of mechanical separation of the toner from the contact object, for example, the photoconductor and the intermediate transfer body, and the transfer behavior from the photoconductor to the intermediate transfer body in the primary transfer unit and the secondary transfer unit In the transfer behavior from the intermediate transfer member to the transfer material at the time. For this reason, accurate color reproduction cannot be performed. If the difference in dynamic friction coefficient exceeds 0.2,
The color reproducibility is reduced, resulting in an inferior image in which hollow occurs in a specific color.

Further, according to the present invention, the absolute values of the charge amounts of the yellow toner, magenta toner, cyan toner and black toner of the color toners are defined as YQ, MQ, CQ and K, respectively.
When Q is set, it is preferable to satisfy the relationship of (Equation 2).

That is, pigments and dyes, which are colorants used in color toners, are determined with priority given to color reproducibility. Therefore, the amount of addition differs depending on the pigment or dye, and the effect on the chargeability of the toner also differs.

(Equation 2) shows the difference in the amount of charge between the color toners. If the difference is large, the developability and transferability between the colors are different. Since the transfer step is a step of transferring the toner by electrostatic force, the toner charge amount has a great influence. The difference in toner charge amount in the developing unit may be corrected for each color, but the behavior in the secondary transfer unit, which is batch transfer, cannot be corrected for each color. For this reason, accurate color reproduction cannot be performed. If the difference in charge amount exceeds 30 μC / g, accurate color reproduction is not performed, resulting in a poor image.

In the color toner of the present invention, the dynamic friction coefficient of the toner is preferably in the range of 0.15 to 0.35. When the coefficient of kinetic friction is less than 0.15, although toner dropout in the transfer portion is reduced, toner cannot be collected in the cleaning portion, and waste toner remains on the photoconductor. If it exceeds 0.35,
In addition to the frequent occurrence of voids in the image, the cleaning blade is easily peeled off, and filming and crying of the photoreceptor occur.

Further, in the toner of the present invention, the absolute value of the charge amount is preferably 10 to 40 μC / g. If the absolute value of the charge amount is less than 10 μC / g, the transfer efficiency of the toner is low, a large amount of waste toner is generated, the waste toner collection box becomes large, and miniaturization of the device becomes difficult. Conversely, 40 μC /
When the value exceeds g, the image density becomes low.

As one means for adjusting the dynamic friction coefficient and the charge amount, a method in which one or more external additives are combined and the adhesion state of the external additives is controlled by an external addition method is used. Can be As the fine powder material, silica fine powder which is a silicon oxide fine powder, titanium oxide fine powder, titanate type fine powder, zirconiaate type fine powder is preferable, and particularly a mixed type of silica fine powder and other fine powders. The use of a combination of the above is more preferred.

Silica is silica fine particles produced by the vapor phase oxidation of a halogenated silicate compound, and utilizes, for example, a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame. Further, the external additive fine powder is subjected to a hydrophobic treatment for environmental stability. Hydrophobic silica surface-treated with dimethyldichlorosilane, hexamethylenedisilazane, polydimethylsiloxane, and aminosilane is preferable, but the selection of a hydrophobizing agent greatly affects not only the chargeability but also the dynamic friction coefficient.

Further, the adsorption of nitrogen by such hydrophobic silica is
BET specific surface area is 35-350m ^Two/ G range
Is preferred. Hydrophobic silica is generally used for toner base particles 1
0.1 to 5 parts by weight per 100 parts by weight, preferably 0.1 to 5 parts by weight.
2-3 parts by weight are blended.

The fine silica powder doped with Sb—Sn and imparting conductivity is effective in suppressing the charge amount and improving the rising property.

The titanium oxide has a BET specific surface area of 10 to 1
Those having 10 m ² / g and a hydrophobicity of 20 to 70 are preferred.
Further, it is preferable that the surface is treated with an aluminum coupling agent, a silicone oil, a silane coupling agent or the like.

Among the inorganic fine particles, titanate-based fine powder and zirconiaate-based fine powder are more preferably used because they have the effect of increasing the coefficient of kinetic friction. Fine particles prepared by the below-described method of synthesizing fine particles, oxalate pyrolysis, or the like can be suitably used.

For example, in the oxalate pyrolysis method, in the case of barium titanate fine particles, TiCl ₄ (aq) and BaCl ₂
・ Mix 2H ₂ O mixed solution A (maintained at 30 ° C or lower)
Oxalic acid (COOH) ₂ · 2H ₂
BaTiO (C ₂ O ₄ )
· 4H obtain ₂ O. By heating this to 600 ° C. or more, BaTiO ₃ fine particles can be obtained. The method of synthesizing fine particles under hydrothermal conditions includes hydrothermal oxidation, hydrothermal precipitation, hydrothermal synthesis, hydrothermal dispersion, hydrothermal crystallization, hydrothermal hydrolysis, and hydrothermal atomizer. There are a mixing method, a hydrothermal mechanochemical method and the like. Preferred are hydrothermal oxidation, hydrothermal precipitation, hydrothermal synthesis, hydrothermal dispersion and hydrothermal hydrolysis.

Materials synthesized by the hydrothermal method include C
aSiO_Three, LaCrO_Three, AlPO _Four, NbP_ThreeO_Four, L
aFeO_Three, LiNbO_Three, SrTiO_Three, BaTiO_Three,
CaTiO_Three, PbTiO_Three, FeTiO_Three, SrZr
O_Three, BaZrO_Three, CaZrO_Three, PbZrO_Three, MnS
iO_Three, MgSiO_Three, MoO_Two, SnO_Two, ZnO_Two, M
gO_Two, NiO, V_TwoO_Five, Nb_TwoO_Five, WO_Two, Nb_TwoO_Three−
TiO_Two, Ta_TwoO_Five-TiO_Two, V_TwoO_Five-ZnO_TwoEtc.
I can do it. Preferably, SrTiO_Three, BaTiO_Three, M
gTiO_Three, AlTiO_Three, CaTiO_Three, PbTiO_Three,
FeTiO_Three, SrZrO_Three, BaZrO_Three, MgZr
O_Three, AlZrO_Three, CaZrO_Three, PbZrO_Three, MnS
iO_Three, CaSiO_Three, MgSiO_ThreeAnd more preferred
Or SrTiO_Three, BaTiO_Three, MgTiO_Three, AlT
iO_Three, CaTiO_Three, PbTiO_Three, FeTiO_ThreeEtc.
Tantalate, SrZrO_Three, BaZrO_Three, MgZr
O_Three, AlZrO_Three, CaZrO_Three, PbZrO_ThreeJill, etc.
There are konates.

The inorganic material such as titanate or zirconate fine particles has an average particle diameter of 0.05 to 4 μm, a BET specific surface area by nitrogen adsorption of 0.1 to 40 m ² / g, and preferably an average particle diameter of 0.1 to 40 m ² / g. 0.1 to 3 μm, BET specific surface area by nitrogen adsorption of 1.0 to ²⁰ m ² / g, more preferably average particle diameter of 0.5 to 2 μm, BET specific surface area by nitrogen adsorption of 2
１５15 m ² / g. Furthermore, the static bulk density is 0.2 to 1.2
Using the inorganic fine particles is g / cm ^3, further by a true specific gravity using an inorganic fine particle is 5.0~8.5g / cm ^3, further improved dispersibility of inorganic fine particles, the toner base particles , And the continuous printing characteristics are stabilized by stabilizing the adhesion state of the external additive for a long period of time.

When the average particle size is less than 0.05 μm, the dispersibility of the inorganic fine particles deteriorates, the aggregates increase, and image defects occur. Further, the BET specific surface area by nitrogen adsorption is 40 m ^2.
/ G or more, the dispersibility of the inorganic fine particles similarly deteriorates,
Aggregates increase, resulting in image defects. Static bulk density 0.2g
/ Cm ³ or less, the cohesiveness of the inorganic fine particles is increased and the dispersion is deteriorated.

When the average particle size is 4 μm or more, the toner particles are separated from the base particles of the toner, and cause unnecessary damage to the photoreceptor. When the BET specific surface area due to nitrogen adsorption is 0.1 m ² / g or less, the number of coarse particles increases, the particles are separated from the base particles of the toner, the surface state of the toner changes with time, and the transfer efficiency is unstable.

The fine particles synthesized by this method can be obtained as spherical fine particles with little aggregation, narrow particle size distribution, and good fluidity. Therefore, when externally added and mixed to the toner, the toner has good dispersibility and adheres uniformly to the toner. And since the shape is spherical, there is no unnecessary damage to the photoreceptor.

The amount of addition of these inorganic fine particles is
0.1 to 5.0 parts by weight to 0 parts by weight is preferred.
When the content is 0.1 part by weight or less, the effect of controlling the dynamic friction coefficient is small, and when the content is 5.0 parts by weight or more, cohesiveness becomes strong,
Unnecessary damage to the photoconductor.

As described above, the effect of the external additive on the chargeability and the dynamic friction coefficient of the toner differs depending on the composition, particle size, surface treatment agent, and amount added.

In the external addition method, when an external additive is externally added to the toner matrix so as to be partially buried in the toner matrix, the toner and the external additive are integrated, so that the dynamic friction coefficient and the charge amount of the toner are reduced. . The external additive strength depends on the shape of the blade of the mixer, the number of rotations,
It is affected by the time, the temperature in the tank, the amount of the charge, and the toner material used.

It is also effective to carry out a fine powder classification step after the external addition step in order to further reduce the amount of liberated external additives and to suppress the temporal change of the toner surface state. At this time, the classification conditions are changed for each color toner, and the amount of external additives on the surface and the particle size distribution of the toner are adjusted to adjust the amount of charge between the toners and the dynamic friction coefficient caused by the surface state. It is.

When the classification condition is changed and the classification is performed under the condition of increasing the cut point, the amount of the external additive in the toner decreases. This is due to the fact that the finer the powder, the larger the specific surface area and the larger the amount of the external additive adhering to the surface. And
As the amount of the external additive decreases, the charge amount and the dynamic friction coefficient decrease.

The pigment or dye used for the colorant used in the color toner of the present invention includes carbon black,
Iron black, graphite, nigrosine, metal complex of azo dye, anthraquinone dye, phthalocyanine blue, Dupont oil red, aniline blue, benzine yellow, hansa yellow, rose bengal, rhodamine lake, alizarin lake, C.I. I. Pigment Red 2
2, 31, 48-1, 48-3, 53-1, 57-1,
60, C.I. I. Pigment Yellow 12, 13, 1
4, 17, 81, 97, 154, 155, 174, 18
0, C.I. I. Pigment Blue 15, 15-3, 15
-4, 15-6, 60 and mixtures thereof can be used. If necessary, magnetic particles can be added as a coloring agent. The magnetic particles include metal powders such as iron, manganese, nickel, and cobalt, and iron, manganese,
A ferrite powder of nickel, cobalt, zinc or the like is used. The average particle size of the powder is preferably 1 μm or less, particularly preferably 0.6 μm or less.

The content of the colorant is preferably 2 to 15% by weight. When the content of the coloring agent is less than 2% by weight, the coloring power becomes weak, and when it exceeds 15% by weight, the developing sleeve and the like are contaminated by the released coloring agent.

The colorant may be prepared and used in advance by means of melt kneading with a binder resin to improve the dispersibility of the colorant, that is, a so-called master batch. In this case, the content of the coloring agent in the master batch is preferably 60% by weight or less. If it exceeds 60% by weight, the dispersibility of the colorant is reduced, so that the OHP transmissivity is reduced.

A charge control agent may be used for the purpose of controlling the chargeability of the color toner. There are two types of charge control agents, one for positive charge control and the other for negative charge control, and these can be used alone or in combination depending on the purpose of use. Examples of the charge control agent for controlling the positive charge include organic compounds having a basic nitrogen atom, such as basic dyes, nigrosine, pyrimidine compounds, aminosilanes, and quaternary ammonium salts. Examples of the charge control agent for controlling the negative charge include metal-containing azo dyes, metal salts of alkylsalicylic acid, metal salts of naphthenic acid, potassium borate, and fatty acid soaps.

Further, if necessary, Teflon (registered trademark), zinc stearate, polyvinylidene fluoride and the like can be used as a release agent, a flow aid, a charge aid, and a cleaning aid.

The BET specific surface area is FlowS manufactured by Shimadzu Corporation.
orbII2300.

The dynamic friction coefficient is HEIDO manufactured by HEIDON.
It measured using the N14 type friction coefficient measuring device.

The toner to be measured is uniformly applied to the surface of the glass preparation on the stage with a blade to make a thin layer. Next, a cover glass was attached to the indenter attachment portion of the apparatus, the stage was moved with the toner layer sandwiched between the glass preparation and the cover glass, and the frictional resistance at that time was measured with a load converter. However, when this method is used, the toner thinning is not constant, so that the friction coefficient value at the time of measurement tends to vary greatly and the data tends to lack stability.

Using a blade, the toner is uniformly applied to the surface of the glass plate on the stage to make it thinner. Next, a glass plate of 18 mm in length and width was attached to the indenter mounting portion of the apparatus, and a weight of 500 g above the indenter was further placed thereon.
Move back and forth with c for 200 times. Thereafter, the glass preparation and the cover glass are once removed from the apparatus, the attached toner is gently removed by air, and the apparatus is attached to the apparatus again. Next, a load of 10 g was placed on the upper part of the indenter, a load converter was connected, and the display value of the device when the stage was moved at 10 mm / sec was defined as the dynamic friction coefficient.

By using this method, the surface condition of the toner can be measured by the slipperiness and the amount of the toner constituent material such as the external additive remaining on the surface of the glass preparation and the cover glass.

The weight average molecular weight of the binder resin is a value measured by gel permeation chromatography using several kinds of monodispersed polystyrene as standard samples. That is, at a temperature of 25 ° C, tetrahydrofuran is used as a solvent to flow at a flow rate of 1 ml per minute, and a concentration of 0.
This is a value measured by injecting 10 mg of a 5 g / dl tetrahydrofuran sample solution by sample weight. The measurement condition is a condition in which the molecular weight distribution of the target sample is included in a range in which the logarithm of the molecular weight and the count number are linear in a calibration curve obtained from several types of monodisperse polystyrene standard samples.

The softening point of the binder resin was measured by a plunger while heating a 1 cm ³ sample at a heating rate of 6 ° C./min using a flow tester (CFT500) manufactured by Shimadzu Corporation.
g / cm ² , a nozzle having a diameter of 1 mm was extruded, and from the relationship between the amount of plunger descent and the temperature rise temperature characteristic, when the height of the characteristic line was h, the temperature with respect to h / 2 Is the softening point.

The charge amount of the toner was measured by the following procedure in the case of the toner used in the one-component developing method. First, an aluminum suction nozzle having a built-in glass filter is installed near the developing sleeve. The weight of the suction nozzle before the measurement is measured and is defined as A1 (g). Whatma glass filter
社 47mm glass fiber filter GF made by n company
D was used. The suction nozzle is grounded via a capacitor having a capacitance of CμF. At both ends of this capacitor,
Connect a voltmeter.

Next, after the both ends of the capacitor are once short-circuited to make the voltage zero, the developing sleeve is rotated at a peripheral speed of 52.5 mm / s, and the developing device is rotated by a suction machine having a portion in contact with the suction nozzle as an insulator. Suction the toner on the sleeve for 2 seconds. At this time, the developing sleeve and the suction nozzle must not be in contact with each other. The voltage across the capacitor at this time is V
(Volts).

The suction nozzle weight after completion of the suction is A2 (g).
Then, the absolute value of the charge amount of the toner is calculated as (Equation 5).

[0106]

(Equation 5)

In the case of the toner used for the two-component developer, the measurement was performed according to the following procedure.

The carrier to be measured and the toner are mixed at a weight ratio of 95: 5, and are charged into a developing device. The developer consisting of the toner and the carrier conveyed onto the developing sleeve of the developing device is added to the developer.
About 2 g was taken out and measured using a blow-off measuring device TB-200 manufactured by Toshiba Chemical Corporation. At this time, the blow pressure was 0.2 kgf / cm ² , the mesh was 400 mesh, and the measurement time was 30 seconds.

The image density was measured with a reflection densitometer (Macbeth) and evaluated.

The toner production process basically includes a pre-mixing process, a melt-kneading process, a pulverizing and classifying process, and an external addition process of various materials.

The pre-mixing process is a process in which the binder resin and the additives to be dispersed therein are uniformly dispersed by a mixer having stirring blades or the like. As the mixer, a well-known mixer such as a super mixer (manufactured by Kawada Seisakusho), a Henschel mixer (manufactured by Mitsui Miike Kogyo), a PS mixer (manufactured by Shinko Pantech), a Reedige mixer and the like are used.

The melt-kneading process is a process of dispersing an additive in a binder resin by a shearing force, and is a split-segment type twin-screw extruder (Ikegai Co., Ltd.) in which a cylinder and a kneading shaft are divided into a plurality of segments. ) Or a two-roll or three-roll kneader.

In the pulverization classification process, the toner mass obtained by kneading and cooling is roughly pulverized by a cutter mill or the like, and then finely pulverized by a jet mill pulverizer (for example, an IDS pulverizer, manufactured by Nippon Pneumatic Industrial Co., Ltd.). Further, if necessary, fine particles are cut by an airflow classifier to obtain toner particles (toner base particles) having a desired particle size distribution. A mechanical pulverization is also possible. For example, a kryptron pulverizer (Kawasaki Heavy Industries, Ltd.) or a turbo mill (Kawasaki Heavy Industries, Ltd.) that pulverizes toner by charging toner into a minute gap between a fixed stator and a rotating roller. Turbo Industries)
Are used. Classification is a process of separating toner fine powder and free external additives from the toner after the pulverizing step or the toner externally added after the pulverization. This step generally results in 5
Toner particles (toner base particles) having a volume average particle diameter in the range of from 12 to 12 μm, preferably in the range of from 5 to 9 μm are obtained. The external addition process is a process of mixing an external additive such as silica with the toner particles (toner base particles) obtained by the classification. Known mixers such as a Henschel mixer and a super mixer are used for this.

The toner of the present invention can be suitably used for one-component development or two-component development.

When used as a two-component carrier, it is preferable that the carrier be a magnetic material coated with a resin containing conductive fine powder. Examples of the conductive fine powder to be used include metal powder and carbon black, and powders of semiconductive oxides such as titanium oxide and zinc oxide, powders of titanium oxide, zinc oxide, barium sulfate, aluminum borate, and potassium titanate. Examples thereof include those whose surfaces are coated with tin oxide, carbon black, and metal, and the specific resistance of which is preferably 10 ¹⁰ Ω · cm or less.

The core material of the carrier has an average particle size of 20 to
100 μm, preferably 30-80 μm cobalt, iron,
Non-metals such as copper, nickel, zinc, aluminum, brass and glass, and conventionally used materials such as metals and metal alloys are widely used.

To form a coating layer on the core material of the carrier,
Known coating methods, for example, a powder that is a carrier core material,
An immersion method of dipping in a solution for forming a coating layer, a spray method of spraying the solution for forming a coating onto the surface of a carrier core material, and a fluidized bed method of spraying a solution for forming a coating layer while the carrier core material is suspended by flowing air. And a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater to remove the solvent.

Examples of the resin used as the coating layer of the carrier include a straight silicone resin having an organosiloxane bond and its alkyd-modified, epoxy-modified,
Modified products such as urethane modified, fluorine resin, styrene resin,
Acrylic resin, methacrylic resin, polyester resin,
Polyamide resin, epoxy resin, polyether resin,
Phenolic resins and the like can be mentioned, and these can be used alone or in combination. It can also be used as a copolymer.

The silicone resin is preferably a room temperature curing type silicone resin. For example, KR271, KR255, KR1
52 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406,
SH840 (manufactured by Toray Silicone Co., Ltd.) and the like.

In the present invention, it is preferable that the surface contact angle of the carrier coat film is in the range of 90 to 120 degrees. More preferably 95 to 115 degrees, still more preferably 100 to 11 degrees.
5 degrees.

If the contact angle is 90 degrees or less, the low melting point component of the toner tends to adhere, and the carrier deteriorates remarkably. When the contact angle is 120 degrees or more, the uniformity of the surface is too high, the charge amount is hardly increased, and the rising property of the charge is deteriorated. In addition, the coefficient of friction of the surface decreases, and the slipperiness with the toner tends to be too good, and conversely, the rising property of charging tends to deteriorate. In particular, in the configuration in which the waste toner is recycled, the waste toner returning to the developing machine contains a large amount of the toner having a low chargeability, so that the rise of the charge is particularly deteriorated and the fog is increased.

The preferred composition of the resin coat film material is, in particular, a straight silicone resin having only an alkyl group having 1 to 4 carbon atoms such as a methyl group as a side chain group, a straight silicone resin containing a phenyl group in the side chain group, and the like. A mixed system with (meth) acrylic resin is preferred. (Meth) acrylic resin is (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
Preferred are alkyl (meth) acrylate polymer resins such as dodecyl (meth) acrylate, octyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and further have 14 carbon atoms.
By having, as the coating layer, a resin composed of an alkyl (meth) acrylate polymer having a long-chain alkyl of ~ 26, the properties are further improved.

Further, the toner of the present invention is characterized in that the toner image formed on the surface of the image carrier is brought into contact with the surface of the endless intermediate transfer member on the surface of the image carrier, and the toner image is formed on the surface. The primary transfer process for transferring the toner image is repeated a plurality of times. Thereafter, the secondary transfer toner image formed on the surface of the intermediate transfer body is collectively transferred to a transfer material by performing the primary transfer process a plurality of times. It is suitably used for an electrophotographic apparatus having a transfer system configured to execute a transfer process.

This is because the external additive and the state of adhesion of the toner of the present invention are set to an appropriate state, so that the dynamic friction coefficient,
This is because both the charge amounts show an appropriate state, and a decrease in transfer efficiency is suppressed. In addition, since the mutual adhesion between toner particles of the toner is reduced and the aggregation of the toner is reduced, the “hollow-out” phenomenon in which a part of the image is not transferred and a hole is formed due to the aggregation effect of the toner. This is because it can be reduced.

Further, since the difference in the dynamic friction coefficient and the charge amount between the four color toners is suppressed by the external additive, a color image having good color reproducibility can be stably obtained.

Further, the toner of the present invention comprises a plurality of movable image forming units each including a rotating photosensitive member and developing means having toners of different colors to form toner images of different colors on the photosensitive member. The image forming unit group is constituted by arranging units in an annular shape, and the entire image forming unit group is rotationally moved to transfer the toner images of different colors formed on the photosensitive member onto the transfer material in a superimposed position. Used in a color electrophotographic apparatus for forming a color image by using the same. Due to the configuration in which the entire image forming unit rotates, a situation occurs in which the waste toner that has been cleaned from the photoconductor and separated from the photoconductor temporarily and repeatedly adheres to the photoconductor again. Since the released colorant and external additives are contained in a large amount in the waste toner, the waste toner repeatedly contacts the photoconductor, so that the filming on the image carrier becomes extremely liable to occur, and the life of the photoconductor is shortened. Is a factor.

However, by using the toner of the present invention, the chargeability and the dynamic friction coefficient of the four color toners are stable, so that good color reproducibility is maintained for a long time.

(Examples) Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to this.

Example 1 Table 1 shows the thermal characteristics of the binder resin used in this example.

[0130]

[Table 1]

In Table 1, Tg is the glass transition point, Mn
Is a number average molecular weight, Mw is a weight average molecular weight, Mz is a Z average molecular weight, Tm, and Ti are a softening point and an outflow start temperature in a flow tester.

Table 2 shows the wax used in this example and the melting point Twt by the DSC method.

[0133]

[Table 2]

Table 3 shows the properties of the external additives and the surface treatment materials used in this example.

[0135]

[Table 3]

The formulations of the toners used in the examples are shown in Table 4.

[0137]

[Table 4]

Table 5 shows the composition of the color toner sample used in the examples and the method of external addition.

[0139]

[Table 5]

When externally adding a material having a large specific surface area, such as the external additives G1 and G3, it is necessary to take a certain amount of rotation intensity and time because the cohesiveness is strong. , G4, and G5, when a material having a small specific surface area is used, a dynamic friction coefficient tends to decrease when an external addition treatment is performed under the same conditions as described above. Therefore, it is effective to perform the processing in two stages. The processing conditions of the external additives G1 and G3 are Henschel mixer (Mitsui Miike Kogyo Co., Ltd.), the blade shape is Z0 + S0, the number of rotations is 1800 rpm, the time is 6 min, the amount of the mother toner is 1.5 kg, and the temperature in the bath is 38.
Perform at ° C. The processing conditions of G2, G4, and G5 are such that after mixing G1 and G3, a predetermined amount is again charged into a Henschel mixer (manufactured by Mitsui Miike Kogyo KK), and the rotation speed is 1200 rpm and the time is 1 minute.
Do with. That is, the dynamic friction coefficient and the charge amount of the toner are adjusted to appropriate values depending on the type and amount of the external additive, the number of rotations of the external additive mixer, and the processing time.

Toner Bk1, Y1, M1, C1, Bk
2, Y2, M2, C2, Bk3, Y3, M3, and C3 were prepared by the above-mentioned external additive method.

The toners Bk4, Y4, M4, C4
, The external shape is added after the pulverization process, and the blade shape uses Z0 + S0.
The rotation was performed at 1800 rpm, the time was 5 minutes, the amount of the parent toner was 1.5 kg, and the temperature in the tank was 30 ° C. After the external addition process,
By performing the classification process, the amount of the external additive affecting the toner surface state and the amount of the released external additive were adjusted. Specifically, the dynamic friction coefficient was adjusted by changing the classification conditions of the Bk4 toner to make the amount of fine particles larger than that of the other color toners.

The toners Bk5, Y5, M5, and C5 are the same materials as the toners Bk4, Y4, M4, and C4. The toners Bk5, Y4, M4, and C4 are subjected to a pulverizing step, a classification step, and an external addition step under the same conditions.

FIG. 3 is a sectional view showing the structure of an electrophotographic apparatus for forming a full-color image used in this embodiment. FIG.
In the figure, reference numeral 1 denotes an outer casing of a color electrophotographic printer, and a right end face side in the figure is a front face. Reference numeral 1A denotes a printer front plate. The front plate 1A can be freely opened and closed as shown by a dotted line with respect to the hinge shaft 1B on the lower side of the printer outer casing 1, and can be raised and closed as shown by a solid line. The front plate 1A is used for the operation of attaching and detaching the intermediate transfer belt unit 2 to and from the inside of the printer, and for checking and maintaining the inside of the printer such as when a paper jam occurs.
To open the printer and open the printer greatly. The attachment / detachment operation of the intermediate transfer belt unit 2 is designed to be in a direction perpendicular to the rotation axis generatrix direction of the photoconductor.

FIG. 4 shows the structure of the intermediate transfer belt unit 2. The intermediate transfer belt unit 2 includes a unit housing 2a, an intermediate transfer belt 3, and a first conductive elastic body.
A transfer roller 4, a second transfer roller 5 made of an aluminum roller, a tension roller 6 for adjusting the tension of the intermediate transfer belt 3, a belt cleaner roller 7 for cleaning the toner image remaining on the intermediate transfer belt 3, and a cleaner roller 7 It includes a scraper 8 for scraping the collected toner, waste toner reservoirs 9a and 9b for storing the collected toner, and a position detector 10 for detecting the position of the intermediate transfer belt 3. As shown in FIG. 3, the intermediate transfer belt unit 2 is detachable from a predetermined storage portion in the printer outer casing 1 by opening the printer front plate 1A as shown by a dotted line and opening it. The intermediate transfer belt 3 is used by kneading a conductive filler into an insulating resin and forming a film with an extruder. In this embodiment, a polycarbonate resin (for example, Iupilon Z300 manufactured by Mitsubishi Gas Chemical) is used as the insulating resin.
A film formed by adding 5 parts by weight of conductive carbon (for example, Ketjen black) to 95 parts by weight was used. The surface was coated with a fluorine resin. The thickness of the film is about 350 μm, and the resistance is about 107 to 108 Ω · cm. Here, the reason why the intermediate transfer belt 3 is formed by kneading a conductive filler into a polycarbonate resin and forming the film into a film can be used to effectively prevent the intermediate transfer belt 3 from being loosened due to long-term use and accumulation of electric charges. The reason why the surface is coated with the fluororesin is to effectively prevent toner filming on the surface of the intermediate transfer belt due to long-term use.

The intermediate transfer belt 3 is set to a thickness of 100 μm
A first transfer roller 4 and a second transfer roller formed of an endless belt-shaped film made of semiconductive urethane as a base material, and formed with a urethane foam having a resistance of 107 Ω · cm and a low resistance treatment therearound. 5 and the tension roller 6 so as to be movable in the direction of the arrow.

Here, the peripheral length of the intermediate transfer belt 3 is the length in the longitudinal direction of A4 paper (298 m
m) plus a length (62 mm) that is slightly longer than half the circumference of the photosensitive drum (diameter 30 mm) described later.
m.

When the intermediate transfer belt unit 2 is mounted on the printer main body, the first transfer roller 4 is applied to the photosensitive member 11 (shown in FIG.
kg, and the second transfer roller 5 is pressed through the intermediate transfer belt 3 to a third transfer roller 12 (shown in FIG. 4) having the same configuration as the first transfer roller 4 described above. . The third transfer roller 12 is configured to be rotatable following the intermediate transfer belt 3. The cleaner roller 7 is a roller of a belt cleaner section for cleaning the intermediate transfer belt 3. This is a configuration in which an AC voltage for electrostatically attracting toner is applied to a metallic roller. The cleaner roller 7 may be a rubber blade or a conductive fur brush to which a voltage is applied.

In FIG. 3, four fan-shaped image forming units 17Bk, 17Y, 17M, and 17C for each color of black, cyan, magenta, and yellow form an image forming unit group 18 at the center of the printer. Are arranged in an annular shape. Each image forming unit 17Bk, 17Y, 17M,
Reference numeral 17C denotes a printer top plate 1C which is opened about a hinge shaft 1D and is detachable at a predetermined position of the image forming unit group 18. Image forming units 17Bk, 17Y, 17M, 17
C is properly mounted in the printer, so that the mechanical drive system and the electric circuit system on both the image forming unit side and the printer side are connected via a mutual coupling member (not shown), and Electrically integrated.

Image forming unit 1 arranged in an annular shape
7Bk, 17C, 17M, 17Y is a support (not shown)
, Which is driven by a moving motor 19 as a whole, and is fixed and does not rotate.
It is configured to be rotatable around 0. Each image forming unit is rotated by an image forming position 2 facing a second transfer roller 4 that sequentially supports the intermediate transfer belt 3 described above.
1 can be located. The image forming position 21 is the signal light 2
2 is also the exposure position.

Each image forming unit 17Bk, 17C, 17
Since M and 17Y are made of the same components except for the developer put in, the image forming unit 17Bk for black will be described for simplification of description, and the description of the unit for other colors will be omitted. Reference numeral 35 denotes a laser beam scanner disposed below the inside of the printer housing 1, and includes a semiconductor laser (not shown), a scanner motor 35a, a polygon mirror 35b, a lens system 35c, and the like. The pixel laser signal light 22 corresponding to the time-series electric pixel signal of the image information from the laser beam scanner unit 35
Passes through an optical path window 36 formed between the image forming units 17Bk and 17Y and passes through a window 3 opened in a part of the shaft 20.
Through 7 into a fixed mirror 38 in axis 20;
Image forming unit 17B that is reflected and is at image forming position 21
k, enters the image forming unit 17Bk substantially horizontally from the exposure window 25, passes through a passage between a developer reservoir 26 and a cleaner 34 disposed vertically in the image forming unit 17Bk, and is on the left side of the photoconductor 11. The light is incident on the exposed portion of the surface and is scanned and exposed in the generatrix direction.

Since the optical path from the optical path window 36 to the mirror 38 uses the gap between the adjacent image forming units 17Bk and 17Y, the image forming unit group 1
8 has very little wasted space. Also, mirror 3
Since 8 is provided at the center of the image forming unit group 18, it can be constituted by a single fixed mirror, which is simple and easy to align.

Reference numeral 12 denotes a third transfer roller disposed inside the front plate 1A of the printer and above the paper feed roller 39, and a nip portion where the intermediate transfer belt 3 and the third transfer roller 12 are pressed against each other is provided. A paper transport path is formed so that paper is fed by a paper feed roller 39 provided below the printer front plate 1A.

Reference numeral 40 denotes a paper feed cassette provided on the lower side of the printer front plate 1A so as to protrude outward, and can set a plurality of papers S at the same time. 41a and 41b are paper transport timing rollers, 42a and 42b are fixing roller pairs provided on the upper inside of the printer, 43 is a paper guide plate provided between the third transfer roller 12 and the fixing roller pairs 42a and 42b, 44a
44b is a paper discharge roller pair disposed on the paper outlet side of the fixing roller pairs 42a and 42b, 45 is a fixing oil reservoir for storing a silicone oil 46 supplied to the fixing roller 42a, and 47 is a silicone oil applied to the fixing roller 42a. It is an oil supply roller.

Each image forming unit 17Bk, 17C, 17
M, 17Y, and the intermediate transfer belt unit 2 are provided with a waste toner reservoir.

Hereinafter, the operation will be described.

First, as shown in FIG. 3, the image forming unit group 18 is moved from the black image forming unit 17Bk to the image forming position 2.
In one. At this time, the photoconductor 11 is in opposing contact with the first transfer roller 4 via the intermediate transfer belt 3.

In the image forming step, the black signal light is input to the image forming unit 17Bk by the laser beam scanner unit 35, and the image is formed by the black toner. At this time, the image forming speed of the image forming unit 17Bk (60 mm / s equal to the peripheral speed of the photoconductor) and the moving speed of the intermediate transfer belt 3 are set to be the same.
By the action of the transfer roller 4, the black toner image is transferred to the intermediate transfer belt 3.
Is transferred to At this time, a DC voltage of +1 kV was applied to the first transfer roller. Immediately after all the black toner images have been transferred, the image forming units 17Bk, 17C, 17C
M and 17Y as a whole are driven by a moving motor 19 as an image forming unit group 18 to rotate and move in the direction of the arrow in the drawing, and rotate exactly 90 degrees to stop at a position where the image forming unit 17C reaches the image forming position 21. . During this time, since the portions of the toner hopper 26 and the cleaner 34 other than the photoconductor of the image forming unit are located inside the rotation arc at the tip of the photoconductor 11, the intermediate transfer belt 3 does not contact the image forming unit.

After the image forming unit 17C arrives at the image forming position 21, the laser beam scanner unit 35 inputs the signal light 22 to the image forming unit 17C with a cyan signal as before, and forms a cyan toner image. Transfer is performed. By this time, the intermediate transfer belt 3 has made one rotation, and the writing timing of the cyan signal light is controlled such that the next cyan toner image is positionally matched with the previously transferred black toner image. During this time, the third transfer roller 12 and the cleaner roller 7 are slightly separated from the intermediate transfer belt 3 so as not to disturb the toner image on the transfer belt.

The same operation as above was performed for magenta and yellow, and a color image was formed by superimposing the four color toner images on the intermediate transfer belt 3 in position. After the transfer of the final yellow toner image, the toner images of the four colors are collectively transferred to the sheet fed from the sheet cassette 40 by the action of the third transfer roller 12 in a timely manner. At this time, the second transfer roller 5 is grounded, and the third transfer roller 12
, A DC voltage of +1.5 kV was applied. The toner image transferred to the paper was fixed by the pair of fixing rollers 42a and 42b. The sheet was then discharged out of the apparatus via a pair of discharge rollers 44a and 44b. The transfer residual toner remaining on the intermediate transfer belt 3 is cleaned by the action of the cleaner roller 7 to prepare for the next image formation.

Next, the operation in the monochrome mode will be described. In the monochrome mode, first, the image forming unit of a predetermined color moves to the image forming position 21. Next, image formation of a predetermined color and transfer to the intermediate transfer belt 3 are performed in the same manner as before, and the transfer is continued as it is after the transfer, to the next sheet transferred from the sheet cassette 40 by the third transfer roller 12. The image was transferred and fixed.

In the present apparatus, the developing method described in Embodiment 1 was used as the structure of the image forming unit, but an image forming unit having a structure using a conventional developing method may be used.

Table 6 shows the dynamic friction coefficient of each color toner,
This shows the charge amount characteristics.

[0164]

[Table 6]

When an image was formed using the toner samples Bk1, Y1, M1, and C1 manufactured as described above using such an electrophotographic apparatus, no solid lines were disturbed, toner was scattered, and characters were not missing. An extremely high-resolution, high-quality image reproducing a 16-line / mm image with a uniform black image and a density of 1.4 was obtained, and a high-density image with an image density of 1.4 or more was obtained. No fogging of the non-image area occurred. Further, even in a long-term durability test of 5,000 sheets, both fluidity and image density showed little change and stable characteristics. In the transfer, the hollow portion was at a practically acceptable level. The transfer efficiency was 90% or more, and a color image having good color reproducibility was obtained. Similarly, Bk2, Y
2, a combination of M2, C2, Bk3, Y3, M3, C
Similarly, good images were obtained with the combination of No. 3 and the combination of Bk4, Y4, M4, and C4. For the Bk3 toner, the developing process speed is set to 50 to 250 mm /
Even when it was changed to sec, there was no significant change in developability, fixability and hot offset resistance, and a practically satisfactory result was obtained.

However, with the combination of Bk5, Y5, M5, and C5, the transfer efficiency was different for each color, and the color reproducibility was poor, resulting in a poor image.

[0167]

As described above, according to the present invention, an external additive to be added to a toner is specified, and a material and a method are set so that the charge amount and the dynamic friction coefficient of each color toner satisfy a specific relationship. As a result, it was possible to suppress a difference in the developing property and the transfer property between the colors of the color toner. Further, the cleaning property by the blade can be improved, and the removal of foreign matters of the low-resistance substance on the photoreceptor can be effectively performed while satisfying the dropout during the transfer, the fixing property, and the anti-offset property. Furthermore, by specifying the coefficient of friction and the contact angle of the coat film of the carrier,
In the two-component development, the chargeability is improved by making the mixing property with the toner uniform, and it is possible to prevent the occurrence of background fog due to a delay in the charge followability particularly when the toner is rapidly replenished. Further, it is possible to obtain a toner excellent in transferability in a transfer roller and an intermediate transfer.

In addition, it is possible to obtain an excellent toner which can cope with different process speeds.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a color electrophotographic apparatus used in an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of the intermediate transfer belt unit shown in FIG.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a color electrophotographic apparatus.

[Explanation of symbols]

 2 Intermediate Transfer Belt Unit 3 Intermediate Transfer Belt 4 First Transfer Roller 5 Second Transfer Roller 6 Tension Roller 11 Photoconductor 12 Third Transfer Roller 17Bk, 17C, 17M, 17Y Image Forming Unit 18 Image Forming Unit Group 21 Image Forming Position 22 Laser signal light 35 Laser beam scanner 38 Mirror

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/08 374 375 (72) Inventor Masatoshi Maeda 1006 Ojidoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Koichi Fukumoto 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 2H076 AB05 AB12 AB18 AB60 AB61

Claims (9)

[Claims] 1. A color toner comprising at least a binder resin, a colorant, and an external additive, wherein the yellow toner, magenta toner, cyan toner, and black toner of the color toner have dynamic friction coefficients of YF, MF, CF, respectively. KF
Wherein the color toner has the relationship of (Equation 1). (Equation 1) Note that max () represents the maximum value in (),
min () represents the minimum value in (). 2. A color toner comprising at least a binder resin, a colorant, and an external additive, wherein the absolute values of the charge amounts of the yellow toner, magenta toner, cyan toner, and black toner of the color toner are YQ and MQ, respectively. , CQ,
A color toner having a relationship represented by (Equation 2) when KQ is used. (Equation 2) Note that max () represents the maximum value in (),
min () represents the minimum value in (). 3. A color toner comprising at least a binder resin, a colorant, and an external additive, wherein the yellow toner, magenta toner, cyan toner, and black toner of the color toner have dynamic friction coefficients of YF, MF, CF, respectively. K
F, the absolute value of the charge amount is YQ, MQ, CQ, KQ, respectively.
Wherein the relations of (Equation 3) and (Equation 4) are satisfied at the same time. (Equation 3) (Equation 4) Note that max () represents the maximum value in (),
min () represents the minimum value in (). 4. A surface of the intermediate transfer member, wherein a surface of an endless intermediate transfer member is brought into contact with the image carrier by visualizing the electrostatic latent image formed on the image carrier. A primary transfer process for transferring the toner image to the transfer material is repeatedly performed a plurality of times, and thereafter, the overlap transfer toner image formed on the surface of the intermediate transfer body is collectively transferred onto the transfer material by performing the primary transfer process a plurality of times. A color electrophotographic method having a transfer system configured to execute a secondary transfer process for transferring, wherein the color toner according to any one of claims 1 to 3 is used. Method. 5. A plurality of movable image forming units each comprising at least a rotating image carrier and developing means having toners of different colors, wherein toner images of different colors are formed on the image carrier. Unit, an image forming position composed of a single exposure position and a single transfer position, an image forming unit group in which the plurality of image forming units are arranged in an annular shape, and each of the plurality of image forming units. Moving means for rotating the entire image forming unit group to sequentially move to the single image forming position, exposing means for generating signal light, and about the center of rotation of the rotational movement of the image forming unit group, A color electrophotographic apparatus having a mirror for guiding the light of the exposing means to the exposing position, transferring toner images of different colors onto a transfer material in a superimposed manner and forming a color image, Item 7. A color electrophotographic method using the color toner according to any one of Items 1 to 3. 6. An external additive to be added to the color toner is a fine powder of silicon oxide, a fine powder of titanium oxide, a fine powder of titanate,
The color toner according to any one of claims 1 to 3, wherein the color toner comprises at least one of zirconia acid-based fine powders, and the color electrophotographic method according to any one of claims 5 to 6. . 7. The binder resin having a weight average molecular weight Mw of 10,000 or more.
300,000, ratio M between weight average molecular weight Mw and number average molecular weight Mn
w / Mn is 3 to 50, ratio Mz / Mn of Z average molecular weight Mz to number average molecular weight Mn is 10 to 800, 1/2 outflow temperature by Koka flow tester is 80 to 150 ° C, outflow start temperature is 80 to The color toner according to any one of claims 1 to 3, which is a polyester resin obtained by polycondensation of a polyvalent carboxylic acid or a lower alkyl ester thereof at 120 ° C with a polyhydric alcohol. 6. The color electrophotographic method according to any one of 4 to 5. 8. The binder resin has a weight average molecular weight Mw of 100,000 to 500,000, a ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of 40 to 90, and a ratio of the Z average molecular weight Mz to the number average molecular weight Mn. Mz / Mn is 350 to 900, and 1/2 outflow temperature in the Koka flow tester is 105 to 145 ° C.
The color toner according to any one of claims 1 to 3, and the color electrophotographic method according to any one of claims 4 to 5, which is a styrene (meth) acrylic acid alkyl ester copolymer. . 9. The binder resin, which is a main component of the black toner constituting the color toner, has a weight average molecular weight Mw of 100,000 to 500,000, and a ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of 40 to 90. , The ratio Mz / Mn of the Z average molecular weight Mz to the number average molecular weight Mn is 350 to 900, and the 1/2 outflow temperature in the Koka flow tester is 105 to 145 ° C.
The weight average molecular weight Mw of the binder resin which is a main component of the yellow toner, magenta toner and cyan toner constituting the color toner is 10,000 to 300,000. The ratio Mw / Mn of the average molecular weight Mw to the number average molecular weight Mn is 3 to 50, and the Z average molecular weight M
a ratio Mz / Mn of z to the number average molecular weight Mn is 10 to 800,
1/2 outflow temperature is 80 to 15 by Koka type flow tester
The polyester resin obtained by polycondensation of a polyhydric carboxylic acid or a lower alkyl ester thereof having a temperature of 0 ° C and an outflow starting temperature of 80 to 120 ° C with a polyhydric alcohol is a polyester resin according to any one of claims 1 to 3. A color electrophotographic method according to any one of claims 4 to 5, and a color electrophotographic method according to any one of claims 4 to 5.