JPH08320591A - Image forming method - Google Patents

Abstract

PURPOSE: To provide an image forming device having an extremely high transfer efficiency. CONSTITUTION: A toner image formed on a first image holding body is transferred to an intermediate transfer body, and further the image is transferred to a second image holding body. The surface layer of the intermediate transfer body contains 20-80% highly-lubricating powder (or the contact angle of the surface of the intermediate transfer body with water is >=60 deg. and the sliding resistance on the surface is <=200g). The toner consists of at least an inorg. fine powder and toner particles containing a coloring agent dispersed in a binder. The shape factor SF-1 and SF-2 of the toner measured by an image analyzer satisfy the relation of 110<SF-1<=180, 110<SF-2<=140 and (SF-2)-100)}/ (SF-1)-100)}<=1.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method using an electrophotographic system, and more particularly, to a second image after a toner image formed on a first image carrier is once transferred onto an intermediate transfer member.
And an image forming method used in a copying machine, a printer, a fax machine or the like, which is further transferred onto the image carrier to obtain an image formed product.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member is
A color image forming apparatus, a multicolor image forming apparatus, or a color image that sequentially outputs a plurality of component color images of color image information or multicolor image information by layered transfer and outputs an image formed by synthesizing and reproducing the color image or the multicolor image. It is effective as an image forming apparatus having a forming function and a multicolor image forming function, and it is possible to obtain an image with no misregistration (color misregistration) of each component color image.

FIG. 1 schematically shows an example of an image forming apparatus which is a transfer apparatus using an intermediate transfer member having a roller shape.

FIG. 1 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process. Medium resistance elastic roller 20 as an intermediate transfer member
Are using.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image bearing member, and rotates at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. Driven.

In the course of rotation, the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2, and then image exposing means (color separation of color original image The first exposure of the target color image by receiving the image exposure 3 by the imaging exposure optical system, the scanning exposure system by the laser scanner which outputs the laser beam modulated corresponding to the time series electric digital pixel signal of the image information). An electrostatic latent image corresponding to the color component image (for example, magenta component image) is formed.

Then, the electrostatic latent image is transferred to the first developing device 41.
It is developed by the magenta toner M which is the first color by the (magenta developing device). At this time, the second to fourth developing devices 42,
43, 44 (cyan, yellow, black developing devices)
Is activated-off and does not affect the photosensitive drum 1,
The magenta toner image of the first color is not affected by the second to fourth developing units 42 to 44.

The intermediate transfer member 20 is rotationally driven in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drum 1.

The intermediate transfer member 20 of this embodiment comprises a pipe-shaped cored bar 21 and an elastic layer 22 formed on the outer peripheral surface thereof.

The above-mentioned first formed and carried on the photosensitive drum 1.
While the color magenta toner image passes through the nip portion between the photosensitive drum 1 and the intermediate transfer body 20, the outer peripheral surface of the intermediate transfer body 20 is formed by the electric field formed by the primary transfer bias applied to the intermediate transfer body 20. Are sequentially transferred to the intermediate transfer.

The surface of the photosensitive drum 1 on which the transfer of the magenta toner image of the first color corresponding to the intermediate transfer member 20 is completed is cleaned by the cleaning device 14.

Similarly, the second color cyan toner image, the third color yellow toner image, and the fourth color black toner image are sequentially transferred onto the intermediate transfer member 20 in a superimposed manner to form a composite color image corresponding to the target color image. A toner image is formed.

Reference numeral 25 denotes a transfer roller, which is arranged in parallel with the intermediate transfer member 20 so as to be in contact with the lower surface of the transfer roller.

First from the photosensitive drum 1 to the intermediate transfer body 20
~ The primary transfer bias for the sequential superposition transfer of the toner image of the fourth color is the bias power source 6 with the polarity (+) opposite to that of the toner.
It is applied from 1. The applied voltage is, for example, +2 kV to +
It is in the range of 5 kV.

First from the photosensitive drum 1 to the intermediate transfer body 20
The transfer roller 25 and the intermediate transfer member cleaner 35 may be separated from the intermediate transfer member 20 in the step of sequentially transferring the fourth color toner image.

The transfer of the composite color toner image superposedly transferred onto the intermediate transfer member 20 onto the transfer material 24 which is the second image carrier is carried out while the transfer roller 25 is in contact with the intermediate transfer member 20. The transfer material 2 is transferred from the paper cassette 9 to the contact nip between the intermediate transfer body 20 and the transfer roller 25 at a predetermined timing.
4 is fed, and at the same time, the secondary transfer bias is applied from the bias power source 29 to the transfer roller 25. The secondary transfer bias causes the synthetic color toner image to be transferred from the intermediate transfer member 20 to the transfer material 24 which is the second image carrier. The transfer material 24 that has received the toner image transfer is introduced into the fixing device 15 and is heated and fixed.

After the transfer of the image to the transfer material 24 is completed, the transfer residual toner on the intermediate transfer body 20 is cleaned by contact with the intermediate transfer body cleaner 35.

In a color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer member, a second image carrier is attached or adsorbed on a transfer drum which is a conventional technique, and the first image carrier is attached thereto. A color electrophotographic apparatus having an image forming apparatus for transferring an image from the body is superior to the transfer method as described in, for example, JP-A-63-301960 in the following points. That is, there is little color shift when the toner images of the respective colors are superposed. Next, FIG.
As shown in, the image can be transferred from the intermediate transfer member without requiring any processing or control (for example, gripping by a gripper, adsorbing, giving a curvature, etc.) to the second image bearing member. A wide variety of two image carriers can be selected.

For example, thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper) can be selected. Transfer is possible regardless of whether the second image carrier is wide or narrow. Furthermore, it is possible to handle envelopes, postcards, label paper, and the like.

Further, since the intermediate transfer member is excellent in rigidity, it is unlikely that the dimensional accuracy such as dents, strains, and deformations due to repeated use is changed, so that the frequency of replacement of the intermediate transfer member can be reduced.

As described above, due to the advantage of using the intermediate transfer member, a color copying machine, a color printer or the like using this image forming apparatus has already started to operate in the market.

However, when the image forming apparatus using this intermediate transfer member is actually used repeatedly in various environments,
It still has the following problems.

[0023]

[Problems to be Solved by the Invention]

(1) The transfer efficiency from the first image carrier, for example, the photosensitive drum to the intermediate transfer member, and the transfer efficiency from the intermediate transfer member to the second image carrier, such as paper or OHP sheet, are sufficiently high. Not not. Therefore, a cleaning device that must be installed on the photosensitive drum and the intermediate transfer member is indispensable, and
Since a large amount of transfer residual toner is cleaned, the load on the member is increased, the life of the member is shortened, and at the same time, the cleaning device is considerably complicated in structure and expensive.

(2) The image transferred to the intermediate transfer member and a part of the image transferred to the second image carrier are not transferred as shown in FIG. It may be). This is because the transfer efficiency has not reached 100% as described in (1). As the cause, it seems that the material used for the intermediate transfer member, the surface property, the resistance, or the magnitude of the applied bias at the time of transfer, the timing thereof or the mechanical configuration of the image forming apparatus, etc., act in a complex manner, The main cause is unknown. However, as the durability of the intermediate transfer body progresses,
Or, it is known that the lower the temperature and humidity, the worse the temperature.

(3) The surface properties and resistance of the intermediate transfer member may change as the durability of the intermediate transfer member is repeatedly used. In the worst case, the surface of the intermediate transfer member is scraped, which makes it impossible to maintain a good transfer efficiency initially obtained and a uniform image.

(4) As shown in FIG. 1, the intermediate transfer body 20 is provided with an intermediate transfer body cleaner 35. This is an apparatus for removing the untransferred toner from the intermediate transfer member by the time when the next series of transfer steps is started. As this cleaning method, there are various methods such as blade cleaning, fur brush cleaning, or a combination thereof. When the cycle of transferring toner on the surface of the intermediate transfer body 20-adhering-releasing is repeated several thousand times or tens of thousands times, The toner that cannot be completely removed by the cleaner 35 gradually accumulates on the surface of the intermediate transfer body 20, and so-called filming is formed. In this case, the transferability of the toner from the first image carrier is deteriorated, and the image quality is reduced or the overall transfer efficiency is deteriorated due to a spotted white image due to poor transfer of the filmed portion. Invite. In order to prevent such toner filming, it is known that the contact angle of the surface is increased as shown in JP-A-6-95517. However, those having a large contact angle on the surface include those having tack, which is not preferable.

(5) To express the function of the intermediate transfer member,
In many cases, rubber, elastomer, resin or the like is used as the material for the elastic layer, and if necessary, a coating layer or the like is used as the upper layer. For example, some preferable materials and compositions have been already disclosed in JP-A-4-81786, JP-A-4-88385, JP-A-3-242667, JP-A-5-333725 and the like, but they have not been disclosed yet. The resistance is stable in a wide range from low-temperature low-humidity environments to high-temperature high-humidity environments, and no usable product has been found.

Further, with the purpose of more fully exhibiting the function of the intermediate transfer member used in the present invention, a proposal for selecting a more preferable toner and expecting its synergistic effect is still found. It has not been.

For example, a full-color image device using a drum-shaped intermediate transfer member is proposed in US Pat. No. 5,187,526. However, US Pat.
No. 26 does not specifically describe the shape and constitution of toner particles.

Further, JP-A-59-15739 discloses
A recording method for transferring a toner image formed of a toner having an average particle diameter of 10 μm or less to an intermediate transfer member and further transferring the toner image on the intermediate transfer member to a transfer material is described. As one method, a method of directly purifying toner particles using a suspension polymerization method is described.

However, the transfer process described in Japanese Patent Application Laid-Open No. 59-15739 is transfer using pressure transfer or adhesive transfer, and the surface of the intermediate transfer member is easily contaminated during the durability of many sheets, resulting in an electric field. It is completely different from the transfer process in which the toner image is transferred mainly using the electric attraction.

Further, in JP-A-59-50473, a surface formed of a heat-resistant elastic layer and an addition polymerization type silicone rubber on a surface of a support on which a toner image on an image bearing body is heated to a predetermined temperature is formed. And an electrophotographic copying method in which the toner image on the intermediate transfer member is further transferred to a transfer material.

However, in the image forming method disclosed in Japanese Patent Laid-Open No. 59-50473, the image bearing member which is in contact with the heated intermediate transfer member is easily deteriorated. JP-A-59-504
No. 73, there is no description of a transfer process using an intermediate transfer member to which a voltage is applied. In a system using an intermediate transfer member, it is necessary to once transfer a toner image from an electrostatic image holding member such as a photoconductor to the intermediate transfer member, and then transfer the toner image again onto the transfer material. It is necessary to improve the transfer efficiency of toner more than ever.

Further, since the transfer efficiency from the intermediate transfer member to the transfer material is poor, a cleaning member is essential for the intermediate transfer member, but this is not preferable in terms of the life of the intermediate transfer member and improvement in transfer efficiency is required. Was there.

Further, Japanese Patent Laid-Open No. 61-279864 proposes toners which define SF-1 and SF-2. However, as a result of carrying out the examples of the publication, the transfer efficiency is low, and especially when used in an image forming apparatus using an intermediate transfer member, the transfer efficiency is insufficient, and further improvement is required.

Further, Japanese Patent Application Laid-Open No. 63-235953 proposes a magnetic toner spherically formed by a mechanical impact force. However, the transfer efficiency when used in an image forming apparatus using an intermediate transfer body is still insufficient, and further improvement is required.

However, the present invention proposes an image forming method using a novel toner and intermediate transfer member which solves the above-mentioned problems.

An object of the present invention is to provide an image forming method in which the transfer efficiency from the first image carrier to the intermediate transfer member and the transfer efficiency from the intermediate transfer member to the second image carrier are extremely high. is there.

Another object of the present invention is to provide a uniform image quality of a second image carrier, such as a paper or an OHP sheet, which does not cause a so-called void image and does not cause transfer failure of a minute portion of an image. An object of the present invention is to provide an image forming method that can be achieved without depending on the type.

Still another object of the present invention is to provide an image forming method capable of maintaining the same characteristics as those at the initial stage without changing the characteristics of the intermediate transfer body even if the intermediate transfer body is subjected to severe durable use by repeated use. To provide.

A further object of the present invention is to provide an image forming method which does not cause filming due to adhesion of toner to the surface of an intermediate transfer member.

A further object of the present invention is to provide an image forming method which does not adversely affect the organic photoconductor and has a long photoconductor life.

[0043]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to achieve the above-mentioned various objects, a substance containing a highly lubricating powder is used as a substance constituting the surface layer of an intermediate transfer member. It is found that the above object can be achieved by preferably defining the contact angle and slip resistance of the surface of the intermediate transfer member, and limiting the shape factor of the toner used to a favorable range. The present image forming method has been completed.

That is, the present invention provides an image forming method in which a toner image formed on a first image carrier is transferred to an intermediate transfer member and then further transferred to a second image carrier. The surface layer of the body is highly lubricious powder 20-80
Mass% and the toner is a toner having at least toner particles in which a colorant is dispersed in a binder resin and an inorganic fine powder, and the toner has a shape factor SF-measured by an image analyzer. The value of 1 is 110 <SF-1 ≦ 18
0, the value of SF-2 is 110 <SF-2 ≦ 140, and {(SF-2) -100)} / {(SF-1) -10.
0)} is 1.0 or less.

The present invention also provides an image forming method in which the toner image formed on the first image carrier is transferred to the intermediate transfer member and then further transferred to the second image carrier. The contact angle of water on the surface of the body is 60 ° or more and the slip resistance is 200 g or less, and the toner is a toner having at least toner particles in which a colorant is dispersed in a binder resin and inorganic fine powder. , The value of the shape factor SF-1 measured by the image analyzer of the toner is 110 <SF-1 ≦
180, the value of SF-2 is 110 <SF-2 ≦ 140, and {(SF-2) -100)} / {(SF-1) -10.
0)} is 1.0 or less.

In the electrophotographic image forming method of transferring the image formed on the first image bearing member to the intermediate transfer member and then further transferring it onto the second image bearing member, the object of the present invention described above. In order to achieve the above, it is necessary to give sufficient lubricity to the surface of the intermediate transfer member. Due to the surface lubricity of the intermediate transfer member, the adhesive force of the toner is reduced, so that the secondary transfer property and durability are improved, and at the same time, filming can be prevented and abrasion of the photoconductor can be reduced. For that purpose, it is preferable to add a lubricant to the constituent material of the intermediate transfer member. However, when a liquid lubricant such as silicone oil is used, the so-called lubricant exudes on the surface of the intermediate transfer member over time. Bleeding may occur, and the lubricant that has exuded may adhere to the photoconductor to cause serious defects such as cracks on the photoconductor surface. This tendency is particularly remarkable when an organic photoconductor is used. Therefore, in the present invention, by imparting a high lubricity to the surface of the intermediate transfer member by adding a specific amount of highly lubricating powder to the substance constituting the surface layer of the intermediate transfer member,
By defining the contact angle of water on the surface of the intermediate transfer member and the slip resistance within a preferred range, it is possible to prevent the occurrence of bleeding, which is a harmful effect of using a lubricant, and to prevent high transfer efficiency and filming. Is something that can be done. These effects can be expected to improve the level to some extent even when the conventional toner is used, but by using the toner of the present invention, the transferability can be further improved. The transfer efficiency of about 90% when using the conventional toner,
It has been found that a transfer efficiency of 95% or more, and further 97% to 98% can be obtained.

Even more surprisingly, by using the intermediate transfer member and the toner of the present invention, the transfer to the second image carrier can be carried out without using an expensive and complicated device such as the above-mentioned intermediate transfer member cleaner 35. After that, it was found that the toner remaining on the intermediate transfer member can be removed by cleaning.

That is, a bias is applied instead of the intermediate transfer member cleaner 35 as shown in FIG. 7 by using an intermediate transfer member having a highly releasable surface and a high transferability, high releasability toner together. The toner 71 on the intermediate transfer body 20 can be removed by cleaning simply by bringing the intermediate resistance cleaning roller 70 into contact with the intermediate transfer body 20.

When the toner 71 on the intermediate transfer member 20 passes through the cleaning roller 70, an appropriate bias is applied by the roller 70. As a result, the toner 71 is given a preferable charge that is easily attracted to the photosensitive drum 1, and passes through the nip portion between the photosensitive drum 1 and the intermediate transfer member 20. At this time, the toner image 72 on the photosensitive drum 1 is intermediately transferred by the electric field formed by the primary transfer bias applied to the intermediate transfer body 20, and at the same time, the toner 71 is transferred.
Will be collected on the photosensitive drum 1 under the above-mentioned electric field. By this action, the toner 71 on the intermediate transfer member 20
Are collected in the photosensitive drum 1 and housed in the cleaner 14. Toner is removed and cleaned from the surface of the intermediate transfer body 20. Further, at the next moment, the toner image 72 is transferred to the surface of the previously cleaned intermediate transfer body.

Such an effect of simultaneous transfer of cleaning can be achieved only by the combination of the toner and the intermediate transfer member having the high releasing property and the high transfer property as in the present invention.

If the releasability of the toner is poor, no matter how high the bias is applied by the cleaning roller 70 and the high charge is applied, it is impossible to completely collect the toner on the photosensitive drum 1 at the nip portion. Similarly, if the transfer efficiency is low, the toner 71, which is the residual toner after the secondary transfer, is unexpectedly large, and again, it is impossible to collect all the toner at the nip portion.

The releasability of the intermediate transfer body 20 is the same as described above, and it is necessary to create a state in which the toner 71 is easily separated from the surface of the intermediate transfer body.

The highly lubricious powder used in the present invention can impart lubricity to the surface of the intermediate transfer member, and the following method is used to judge the lubricity of the powder used in the present invention. be able to.

20 parts by mass of the powder to be tested and the resin used for the surface layer of the intermediate transfer member, for example, urethane prepolymer 100
5 parts by mass of a curing agent are added and mixed, and then spray coated onto a PET plate to prepare a test sample. At this time, the viscosity of the paint is adjusted with a mixed solvent such as toluene or MEK that can dissolve, and care is taken to obtain a uniform paint surface. On the other hand, a comparative coating sample is prepared in the same manner except that the powder to be tested is not added. Next, the surface resistance measuring device HEIDON-14DR (manufactured by Shinto Scientific Co., Ltd.) is used to measure the slip resistance of both. As a measuring method, an unpainted PET plate as an object to be measured is fixed to an ASTM flat indenter, and a coated sample is horizontally moved at a speed of 100 mm / min under a vertical load of 200 gf. If the slip resistance of the test sample is 80% or less of that of the comparative sample, the test powder can be judged as a highly lubricious powder.

On the other hand, when the physical properties are such that the contact angle of water on the surface of the intermediate transfer member is 60 ° or more and the slip resistance is 200 g or less, the releasability of the toner is large and the transfer efficiency is improved. Therefore, the filming resistance is also good at the same time. Further, by increasing the contact angle with water, there is also an effect of reducing the environmental dependence of the electric resistance. It is speculated that this is because the surface of the intermediate transfer member is hydrophobic, so that the intermediate transfer member is less likely to absorb moisture and less affected by humidity in the use environment. Further, since the transfer efficiency is improved and the cleaning can be performed with the simple cleaning device as described above, the load on the surface of the intermediate transfer member is reduced, and as a result, the life of the intermediate transfer member is improved. The contact angle of water on the surface of the intermediate transfer body is 60.
If it is less than ° or the slip resistance exceeds 200 g, the releasability of the toner becomes small and the transfer efficiency decreases, the image quality deteriorates,
It also causes filming.

Therefore, in order to achieve the object of the present invention, a material having the above-mentioned characteristics is selected. For example, the following are mentioned, but not limited to these. Fluorine rubber, fluoroelastomer, graphite or fluorocarbon and PTFE in which fluorine is bonded to graphite,
Fluorine compound powders such as PVDF, ETFE and PFA resins, silicone resin particles, silicone rubbers, silicone powders such as silicone elastomers, PE, P
Resins such as P, PS, acrylic resin, nylon resin, phenol resin and epoxy resin and powders of these compounds and mixtures, granular carbon such as spherical graphite, silica, alumina, titanium oxide, magnesium oxide, tin oxide, iron oxide. Inorganic powders, etc. that have been surface treated,
Alternatively, they may be used alone or in combination of two or more.
Further, the shape and particle size of the highly lubricious particles are not particularly limited, and any shape such as spherical, fibrous, plate-shaped, and amorphous can be used as long as lubricity can be obtained, and the particle size is also limited. Although not present, 0.02 to 50μ considering dispersibility and surface properties
m is preferred. These powders may be subjected to a surface treatment, if necessary, within a range that does not impair the lubricity. In addition, a dispersant can be used within a range that does not cause problems in various properties.

In order for the image forming method of the present invention to exhibit the desired effects, the high solidity powders satisfying the objects of the present invention are the total solid content of the substances constituting the surface layer of the intermediate transfer member. It is necessary to occupy 20 to 80% by mass, preferably 25 to 75% by mass. Content is 20% by mass
If it is less than the above range, the lubricity is insufficiently provided, the secondary transfer efficiency and the durability are lowered, and the toner filming occurs. If it exceeds 80% by mass, the adhesion with the binder component will be insufficient and the durability will decrease.

In order to prepare the substance constituting the surface layer of the intermediate transfer member, a known method can be appropriately used as a method of mixing and dispersing such powder in a binder such as resin, elastomer or rubber. . When the binder component is rubber or elastomer, roll mill, kneader,
An apparatus such as a Banbury mixer is used, and when it is in a liquid state, it can be dispersed by using a ball mill, a bead mill, a homogenizer, a paint shaker, a nanomizer or the like.

The highly lubricating powder used in the present invention needs to appear on the surface of the intermediate transfer member, and therefore needs to be added to the composition constituting the surface layer of the intermediate transfer member. When the intermediate transfer member is composed of a plurality of layers, it must be added at least in the outermost layer.

By forming such a surface layer, the contact angle of water and the slip resistance can be set within desired ranges.

As the intermediate transfer member used in the present invention, for example, a roller shape (FIG. 2) having an elastic layer 101 made of rubber, elastomer or resin on the outer peripheral surface of a cylindrical conductive support (core metal) 100, Further, a roller shape having one coating layer 102 on the outer peripheral surface of the elastic layer 101 (FIG. 3), or a roller shape having two coating layers 102 and 103 on the outer peripheral surface of the elastic layer 101 (FIG. 4) Further, the belt shape 104 as shown in FIG. 5 and intermediate transfer members of various modes can be selected according to the purpose and need. In consideration of color misregistration in superimposing images and durability due to repeated use, a more preferable shape of the intermediate transfer body is a roller shape.

The cylindrical conductive support (core bar) can be manufactured using a metal or alloy such as aluminum, iron, copper and stainless steel, a conductive resin in which carbon or metal particles are dispersed, and the like. Examples of the shape include a cylindrical shape as described above, a shape in which a shaft penetrates the center of the cylinder, and a shape in which the inside of the cylinder is reinforced.

The rubber, elastomer, and resins used to form the elastic layer and the coating layer of the intermediate transfer member include, for example, styrene-butadiene rubber, high styrene rubber, butadiene rubber, and isoprene as the elastomer and rubber. Examples thereof include rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicon rubber, fluororubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber and norbornene rubber. Further, as the resins, polystyrene, chloropolystyrene, poly-α-methylstyrene,
Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-
Maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer And styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), Styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer and other styrenic resins (styrene or styrene-substituted homopolymers or copolymers), vinyl chloride resin, styrene- Vinyl acetate copolymer, rosin-modified maleic acid resin, pheno Le resins, epoxy resins, polyester resins, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resins, polyurethane resins, silicone resins, ketone resins, ethylene - ethyl acrylate copolymer, xylene resin and polyvinyl butyral resins.

The thickness of the elastic layer is 0.5 mm or more, and further 1
It is preferably at least mm, particularly preferably 1 to 10 mm.
Further, the film thickness of the coating layer is preferably a thin film in order to convey the flexibility of the lower elastic layer to another coating layer on the coating layer or to the photoreceptor surface, specifically 3 mm.
It is preferably 2 mm or less, more preferably 20 μm to 1 mm.

The volume resistance of the intermediate transfer member is 10 ¹ to 10 ¹³ Ω.
-Cm is preferable, and particularly 10 ² to 10 ¹⁰
It is preferably Ω · cm. Further, the volume resistance of the surface layer is preferably within these ranges.

In order to control the resistance as described above, a conductive agent can be appropriately contained in the elastic layer and the coating layer within the range not impairing the object of the present invention. As the conductive agent, for example,
Examples thereof include various conductive inorganic particles, carbon black, ionic conductive agents, conductive resins, conductive particle dispersed resins, and the like. Specifically, particles of titanium oxide, tin oxide, barium sulfate, aluminum oxide, strontium titanate, magnesium oxide, silicon oxide, silicon carbide, silicon nitride, etc. as conductive inorganic particles may be tin oxide, antimony oxide as necessary. The surface treatment is performed with carbon or the like, and these shapes may be spherical, fibrous, plate-like, or amorphous. The ionic conductive agent is an ammonium salt, an alkyl sulfonate, a phosphoric acid ester, a perchlorate, or the like, and as the conductive resin, a quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl aniline,
Examples thereof include polyvinylpyrrole, polydiacetylene and polyethyleneimine. Examples of the conductive particle-dispersed resin include those obtained by dispersing conductive particles of carbon, aluminum, nickel or the like in a resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer or polymethylmethacrylate. However, although not limited thereto, conductive inorganic particles are preferable as the conductive agent in the coating layer from the viewpoint of controlling conductivity.

On the other hand, in the toner used in the present invention, SF-1 and SF-2 showing the shape factor are, for example, toner images of 2 μm or more magnified 1000 times using FE-SEM (S-800) manufactured by Hitachi Ltd. 100 samples were randomly sampled, and the image information was
For example, the value is calculated by the following equation by introducing it into an image analysis device (Luzex III) manufactured by Nicolet Co.
-1, SF-2.

SF-1 = (MXLNG) ² / AREA × π / 4 × 100 SF-2 = (PERIME) ² / AREA × 1 / 4π × 100 (where MXLNG is the absolute maximum length of the particle, PERIME
Is the perimeter of the particle, AREA is the projected area of the particle) Shape factor SF-1 is the degree of roundness of the toner particles,
The shape factor SF-2 indicates the degree of unevenness of the toner particles.

When a full-color copying machine that transfers a plurality of toner images after development is used, the amount of toner on the intermediate transfer member is increased as compared with the case of one color black toner used in a black-and-white copying machine. When the irregular black toner was used, it became difficult to further improve the transfer efficiency.
Furthermore, when using a black toner having general magnetism,
Due to a sliding force or a rubbing force between the photoconductor and the cleaning member, between the intermediate transfer member and the cleaning member, and / or between the photoconductor and the intermediate transfer member, the toner may be attached to the surface of the photoconductor or the intermediate transfer member. Transferring efficiency is likely to decrease due to fusion or filming. Further, in generating a full-color image, it is difficult to uniformly transfer toner images of four colors including black, and when an intermediate transfer member is used, problems such as color unevenness and color balance easily occur. It is not easy to stably output a high-quality full-color image.

When the toner shape factor SF-1 exceeds 180 or SF-2 exceeds 140, the toner is separated from the spherical shape and approaches an irregular shape, and the toner is easily crushed in the developing unit.
The particle size distribution tends to fluctuate, the charge amount distribution tends to be broad, and background fog and reverse fog are likely to occur. Further, the transfer efficiency of the toner image is reduced during transfer from the electrostatic image carrier to the intermediate transfer member, the transfer efficiency of the toner image is reduced during transfer from the intermediate transfer member to the transfer material, and the line image is skipped during transfer. Is not preferred. Further, when SF-1 is 110 or less or when the shape factor SF-2 of the toner is 110 or less, and {(SF-2) -100} / {(SF-1)-
When 100} exceeds 1.0, cleaning failure generally tends to occur. The present invention solves the above problems by at least setting the shape of the magnetic toner within the scope of the present invention.

Furthermore, the value of SF-1 is 120≤SF-1.
≦ 160 and the value of SF-2 is 115 ≦ SF-2 ≦ 14
0, and a toner produced by a pulverization method is preferably used.

Also, {(SF-2) -100} / {(S
F-1) -100} indicates the slope of a straight line passing through the origin in FIG. 8, and this value is preferably 0.20 to 0.95.
(More preferably 0.35 to 0.85) is preferable in order to improve transferability while maintaining developability.

Further, by including the inorganic fine powder on the surface of the magnetic black toner particles, the transfer efficiency is improved and the voids in the transfer of characters and line images are improved. At this time, BET
Specific surface area Sb per unit volume measured by the method
And the weight average particle diameter (D4) assuming that the toner is a true sphere
Specific surface area St per unit volume calculated from (St = 6
/ D4) is 3.0 ≦ Sb / St ≦ 7.0 and S
It is preferable that b ≧ St × 1.5 + 1.5, and further, Sb is preferably 3.2 to 6.8 m ² / cm ³ , and more preferably 3.4 to 6.3 m ² / cm ³ .

If the ratio is less than 3.0 times, the transfer efficiency is insufficient, and if it exceeds 7.0 times, the image density is lowered. It is considered that this is because the inorganic fine particles added to the toner particles behave effectively as a spacer between the toner particles and the toner image carrier.

The specific surface area of the toner within the above range can be achieved by controlling the specific surface area of the toner particles, the specific surface area of the inorganic fine powder added to the toner particles, the addition amount and the addition mixing strength. If the addition and mixing strength is too high, the inorganic fine particles will be embedded in the toner particles, and the transfer efficiency will not be improved sufficiently.

Further, in order to effectively use the inorganic fine powder, the specific surface area Sr per volume of the toner particles is preferably 1.2 to 2.5 m ² / cm ³ , more preferably 1.4.
˜2.1 m ² / cm ³ , and preferably 1.5 to 2.5 times the theoretical specific surface area per volume calculated from the weight average particle diameter when the toner is assumed to be a true sphere.

The specific surface area is preferably increased by 1.5 m ² / cm ³ or more by adding the inorganic fine powder.
1 nm-100 of the toner particles before adding the inorganic fine powder
nm pores have an integrated pore area ratio of 60% and a pore radius of 3.
It is preferably 5 nm or less. At this time, the toner B
The value of the ratio Sb / Sr of the ET specific surface area Sb and the BET specific surface area Sr of the toner particles is preferably in the range of 2-5.

These are those in which the inorganic fine powder behaves more effectively and the transfer efficiency is improved by reducing the pores in the toner particles which are larger than the primary particle diameter of the inorganic fine powder added to the toner particles. it is conceivable that.

The specific surface area was determined according to the BET method by using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics Co., Ltd.) to adsorb nitrogen gas on the surface of the sample and calculating the specific surface area using the BET multipoint method. Further, the 60% pore radius was calculated from the integrated pore area ratio curve with respect to the desorption side pore radius. In Autosorb 1, the pore size distribution is calculated by Bar
rett, Joyner, & Harenda (BJ.
H). J. The H method is used.

In the present invention, since the intermediate transfer member is provided in order to accommodate various kinds of transfer materials, the transfer step is substantially 2
Since the transfer is performed once, the transfer efficiency is remarkably reduced, which causes a problem that the toner utilization efficiency is reduced. In a digital full-color copying machine or printer, a large amount of toner is placed in correspondence with the color information of the original or CRT, so the toner used in the present invention is required to have an extremely high transferability. The present invention is preferably applicable to black toner, more preferably magnetic black toner.

Further, in order to faithfully develop finer latent image dots for higher image quality, the toner particles preferably have a weight average diameter of 4 to 9 μm. Weight average diameter is 4 μm
If the toner particles are less than 1, the amount of residual toner on the photosensitive member or the intermediate transfer member is large due to a decrease in transfer efficiency, and moreover, it tends to cause uneven image unevenness due to fog and transfer failure. It is not preferable for the toner that does. Also,
When the weight average diameter of the toner particles exceeds 9 μm, scattering of characters and line images is likely to occur.

For the average particle size and particle size distribution of the toner, Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co.) is used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting number distribution and volume distribution and PC980.
1 Personal computer (manufactured by NEC) is connected, and the electrolyte is a 1% NaCl aqueous solution prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan Co.) can be used.
As the measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) as a dispersant is added to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the dispersion was treated as an aperture with the Coulter Counter TA-II type as 10
Using a 0 μm aperture, the volume and number of toner particles of 2 μm or more were measured to calculate the volume distribution and number distribution.
Then, from the volume distribution, the weight-average particle size (D
4), the number average length average particle diameter (D1) was determined from the number distribution.

Further, the charge amount per unit volume (two-component method) of the toner used in the present invention is 30 to 80 C / m ³ , and further 40 to 70 C / m ³ , the transfer member to which a voltage is applied is It is preferable for improving the transfer efficiency in the transfer method used.

The method for measuring the charge amount (two-component tribo value) of the toner according to the present invention by the two-component method is shown below.

In an environment of 23 ° C. and relative humidity of 60%, EFV200 / 300 (manufactured by Powder Tech) was used as a carrier, and a mixture of 9.5 g of carrier and 0.5 g of toner was added to a polyethylene bottle having a capacity of 50 to 100 ml. Shake by hand 50 times. Then, as a suction port at the bottom, 500
1.0 to 1.2 g of the mixture is put in a metal measuring container having a mesh screen, and a metal lid is put on the container. The mass of the entire measurement container at this time is weighed and set to W1g. next,
In the suction device (at least the part in contact with the measurement container is an insulator), suction is made from the lower part of the suction port and the air volume control valve is adjusted to adjust the pressure of the vacuum gauge to 2450 Pa (250 mmAq). In this state, the toner is sucked and removed through the 500 mesh screen for 1 minute. The potential of the electrometer at this time is V (volt). Here, a capacitor is connected to the ammeter and the capacity is C (μF). In addition, the mass of the entire measuring machine after suction is weighed and is W2 (g). The triboelectric charge amount (mC / kg) of this toner is calculated by the following formula.

Triboelectric charge amount (mC / kg) = CV / (W1-W2) Further, the triboelectric charge amount per unit volume (C / m ³ ) can be obtained by multiplying the triboelectric charge amount by the true density.

The true density of the toner is the gas displacement type densitometer Acc.
It was measured using upyc1330 (manufactured by Micromeritics).

The glass transition point Tg of the toner is preferably 50 ° C. to 75 ° C. from the viewpoint of fixability and storability.
C.-70.degree. C. is more preferable.

Glass transition point Tg of the toner used in the present invention
Is measured by, for example, DSC-7 manufactured by Perkin Elmer.
As described above, a highly accurate internal heat input compensation type differential scanning calorimeter is used.

The measuring method is ASTM D3418-82.
Carry out according to. In the present invention, the sample is heated once to obtain a previous history, then rapidly cooled, and then again heated at a rate of 10 ° C./mi.
n, a DSC curve measured when the temperature is raised in the range of 0 to 200 ° C is used.

Examples of the binder resin used in the toner of the present invention include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and their substitution products; styrene-p-chlorostyrene. Copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, Styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin and the like can be used. A crosslinked styrene resin is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene type copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate,
Didecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. A monocarboxylic acid having a heavy bond or a substituted product thereof;
For example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate, and the like; and substituted compounds thereof; for example, vinyl chloride,
Vinyl esters such as vinyl acetate, vinyl benzoate, etc., ethylene-based olefins such as ethylene, propylene, butylene, etc .; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc .;
For example, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether and the like; and vinyl monomers such as are used alone or in combination. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, and examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate and ethylene glycol. Dimethacrylate,
Carboxylic acid esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and compounds having three or more vinyl groups Can be used alone or as a mixture.

As the binder resin for toner used for pressure fixing, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, higher fatty acid, polyamide Resins and polyester resins may be mentioned. These are preferably used alone or as a mixture.

Further, it is also preferable to include the following waxes in the toner from the viewpoint of improving the releasability from the fixing member during fixing and the fixing property. Paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives, etc., and the derivatives include oxides and block copolymers with vinyl monomers. And graft modified products.

In addition, alcohols, fatty acids, acid amides,
Esters, ketones, hydrogenated castor oil and its derivatives, plant waxes, animal waxes, mineral waxes, petrolactam and the like can also be used.

In the toner used in the present invention, a charge control agent can be preferably mixed with the toner particles (internal addition) or mixed with the toner particles (external addition). The charge control agent makes it possible to control the optimum charge amount according to the developing system, and particularly in the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. Examples of substances that control the toner to be negatively charged include the following substances.

For example, organic metal complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol. Further, the following substances are exemplified as those which are controlled to be positively charged.

Modified products with nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and phosphonium salts which are analogs thereof. Onium salts such as and lake pigments thereof, triphenylmethane dyes and lake pigments thereof (as a laker, phosphotungstic acid, phosphomolybdic acid, phosphotungstic molybdic acid, tannic acid, lauric acid, gallic acid, ferricia Metal compounds of higher fatty acids; dibutyltin oxide, dioctyltin oxide, dicyclotintin oxide and other diorganotin oxides; dibutyltin borate, dioctyltin borate, dicyclohexyl Diorgano tin borate such as Suzuboreto; can be used in combination singly or two or more kinds. The charge control agents described above are preferably used in the form of fine particles, and in this case, the number average particle diameter of these charge control agents is preferably 4 μm or less, more preferably 3 μm or less. When these charge control agents are internally added to the developer, it is preferably used in an amount of 0.1 to 20 parts by mass, particularly 0.2 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

Further, as a coloring material which can be further added to the toner used in the present invention, conventionally known carbon black,
Copper-phthalocyanine or the like can be used.

The colorant used in the present invention is mainly a magnetic substance as a black colorant, and if necessary, carbon black, and a color tone adjusted to black by using the following yellow / magenta / cyan colorant is used. To be done.

Examples of magenta colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
A compound represented by an azo metal complex, a methine compound and an allylamide compound is used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 109, 110,
111, 128, 129, 147, 168 and the like are preferably used.

As the yellow colorant, a condensed azo compound, a diketopyrrolopyrrole compound, an anthraquinone, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzimidazolone compound, a thioindigo compound and a perylene compound are used. Specifically, C.I.
I. Pigmentlet 2, 3, 5, 6, 7, 23, 4
8; 2, 48; 3, 48; 4, 57; 1, 81; 1, 1
44, 146, 166, 169, 177, 184, 18
5,202,206,220,221,254 are particularly preferred. As the cyan colorant used in the present invention, a copper phthalocyanine compound and its derivative, an anthraquinone compound, a basic dye lake compound and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15:
1, 15: 2, 15; 3, 15: 4, 60, 62, 66
Etc. can be used particularly preferably. These colorants may be used alone or in combination, and may be used in the form of solid solution.
The amount of the colorant added is 1 to 20 with respect to 100 parts by mass of the resin.
Used by adding parts by mass, 1 to 100 parts of the magnetic material
20 parts can be added.

When a magnetic material is used as the black colorant, it is 30 to 100 parts by mass of the resin, unlike other colorants.
It is used by adding 200 parts by mass. In the present invention, examples of the magnetic substance include metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum and silicon. Among them, those containing iron oxide as a main component such as triiron tetraoxide and Y-iron oxide are preferable. From the viewpoint of toner chargeability control, other metal elements such as silicon element or aluminum element may be contained. These magnetic particles are preferably magnetic powders having a BET specific surface area of ² to 30 m ² / g, especially 3 to 28 m ² / g, and a Mohs hardness of 5 to 7 according to a nitrogen adsorption method.

The shape of the magnetic material is octahedron, hexahedron,
There are spheres, needles, flakes, etc., but those having less anisotropy such as octahedron, hexahedron, sphere, and amorphous are preferable for increasing the image density. The average particle size of the magnetic substance is 0.05 to
1.0 μm is preferable, 0.1 to 0.6 μm is more preferable, and 0.1 to 0.4 μm is particularly preferable.

The amount of magnetic material is 3 with respect to 100 parts by mass of the binder resin.
0 to 200 parts by mass, preferably 40 to 200 parts by mass, and particularly preferably 50 to 150 parts by mass. If the amount is less than 30 parts by mass, in a developing device that uses a magnetic force for toner transportation, the transportability is insufficient, and unevenness in the developer layer on the developer carrier tends to result in image unevenness. The image density tends to decrease due to the above. on the other hand,
There was a tendency for problems to occur in the fixability of more than 200 parts by mass.

As the inorganic fine powder contained in the toner used in the present invention, known ones can be used. To improve the charge stability, developability, fluidity and storability, silica,
It is preferably selected from alumina, titania, or a complex oxide thereof. Furthermore, silica is more preferable. For example, as the silica, both a so-called dry method produced by vapor phase oxidation of a silicon halide or an alkoxide or a dry silica called fumed silica, and a so-called wet silica produced from alkoxide water glass or the like can be used. However, there are few silanol groups on the surface and inside the silica fine powder, and Na ₂ O,
Dry silica having less production residue such as SO ₃ ²⁻ is preferable. Further, in the case of dry silica, it is possible to obtain a composite fine powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride and titanium chloride together with a silicon halogen compound in the manufacturing process. Yes, and include them. Inorganic fine powder used in the present invention is the specific surface area by nitrogen adsorption measured by BET method 30 m ² / g or more, especially given the 50 to 400 m ² / g good results in the range of, relative to 100 mass parts of the toner The silica fine powder is preferably 0.1 to 8 parts by mass, more preferably 0.5 to 5 parts by mass, and particularly preferably 1.0 to
Use 3.0 parts by mass. In addition, the inorganic fine powder used in the present invention may contain a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oil, a silane coupling agent, and a functional group for the purpose of hydrophobizing, controlling chargeability, etc. It is preferable that the silane coupling agent is treated with a treating agent such as a silane coupling agent, an organic silicon compound, an organic titanium compound or the like, or is used in combination with various treating agents.

In order to maintain a high charge amount, achieve a low consumption amount and a high transfer rate, it is more preferable that the inorganic fine powder is treated with at least silicone oil.

Further, in order to improve transferability and / or cleaning property, it is also preferable to further add inorganic or organic near spherical particles having a primary particle size of 50 nm or more (preferably a specific surface area of less than 30 m ² / g). Is one of. For example, spherical silica particles, spherical polymethylsilsesquioxane particles, spherical resin particles and the like are preferably used.

The toner used in the present invention may further contain other additives within a range that does not have a substantial adverse effect, for example, Teflon powder, zinc stearate powder, lubricant powder such as polyvinylidene fluoride powder, or cerium oxide powder, Abrasives such as silicon carbide powder and strontium titanate powder, or fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder, anti-caking agents, or conductivity such as carbon black powder, zinc oxide powder and tin oxide powder. A small amount of an imparting agent, organic fine particles of opposite polarity, and inorganic fine particles can be used as a developing property improver.

A known method is used to prepare the toner used in the present invention. For example, a binder resin, a wax, a metal salt or a metal complex, a pigment as a coloring agent, a dye, a magnetic substance, or a pigment may be used. Accordingly, the charge control agent and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded by using a heat kneader such as a heating roll, a kneader, or an extruder so that the resins are mixed with each other. Metal compounds, pigments, dyes, etc.
The magnetic material is dispersed or dissolved, cooled and solidified, pulverized, subjected to classification and surface treatment to obtain toner particles, and inorganic fine powder is added and mixed to obtain the toner used in the present invention. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

Examples of the surface treatment include a hot water bath method in which pulverized toner particles are dispersed in water and heated, a heat treatment method in which a hot air stream is passed through, a mechanical impact method in which mechanical energy is applied and treated. In the present invention, thermomechanical impact in which the treatment temperature in the mechanical impact method is a temperature (Tg ± 10 ° C.) around the glass transition point Tg of the toner particles is preferable from the viewpoint of aggregation prevention and productivity. More preferably,
Performing at a temperature in the range of the glass transition point Tg ± 5 ° C. of the toner is particularly effective for reducing the pores having a radius of 10 nm or more on the surface, allowing the inorganic fine powder to work effectively, and improving the transfer efficiency.

In the present invention, imparting releasability to the first image carrier is remarkably effective in improving transfer efficiency and preventing voids in transfer.

As means for imparting releasability to the surface layer of the first image carrier, a resin having a low surface energy is used for the resin constituting the film itself, and an additive imparting water repellency and lipophilicity is used. Examples thereof include addition, dispersion of a material having a high releasability into a powder form, and the like. For example, it is achieved by introducing a fluorine-containing group, a silicone-containing group or the like into the resin structure. For this, a surfactant or the like may be used as an additive. Examples thereof include compounds containing a fluorine atom, that is, polytetrafluoroethylene, polyvinylidene fluoride, carbon fluoride and the like.

Of these, polytetrafluoroethylene is particularly preferable. In the present invention, it is preferable to disperse the releasable powder such as the fluorine-containing resin in the surface layer.

In order to contain these powders on the surface, a layer in which the powders are dispersed in a binder resin is provided on the outermost surface of the image bearing member, or an organic material mainly composed of a resin is used. In the case of an image carrier, the powder may be dispersed in the uppermost layer without providing a new surface layer. The addition amount is preferably 1 to 60% by mass, and more preferably 2 to 50% by mass based on the total mass of the surface layer. If it is less than 1% by mass, the effect of improving the durability of the toner and the toner carrier is insufficient, and if it exceeds 60% by mass, the strength of the film is reduced and the amount of light incident on the image carrier is significantly reduced. Therefore, it is not preferable.

The intermediate transfer member of the present invention is manufactured, for example, as follows.

First, a metal roll as a cylindrical conductive support (core bar) is prepared. An elastic layer is provided by molding rubber, elastomer, resin or the like on a metal roll by melt molding, injection molding, dip coating or spray coating. Next, the coating layer is formed by molding the material of the coating layer on the elastic layer by melt molding, injection molding, dip coating, spray coating or the like.

[0118]

The present invention will be described in detail below with reference to examples. In the examples, "part" means "part by mass". (Example 1) Diameter 182 mm, length 320 mm, thickness 5
A roller compound (1) having an elastic layer was obtained by extrusion-molding a rubber compound having the following composition on the surface of a cylindrical roller made of aluminum having a thickness of mm by using a mold and polishing the surface layer.

Rubber compounding: NBR 100 parts Zinc oxide 2 parts Conductive carbon black 10 parts Paraffin oil 30 parts Vulcanizing agent 2 parts Vulcanization accelerator 3 parts

A paint having the following formulation was prepared. Coating composition: Polyester polyurethane prepolymer (including solvent) 100 parts (solid content 40% by mass) Curing agent (including solvent) 50 parts (solid content 60% by mass) Highly lubricious powder PTFE particles (particle size 0.3 μm) ) 200 parts Dispersion aid (low molecular weight resin) 5 parts Conductive titanium oxide particles (particle size 0.5 μm) 10 parts Toluene (solvent) 80 parts

This coating material is spray-applied to the outer peripheral surface of the roller (1) to form a coating layer having a thickness of 80 μm.
By heating at 90 ° C. for 1 hour, the residual solvent was removed and the coating was crosslinked to obtain an intermediate transfer member (1) having a tough surface layer. The proportion of PTFE particles in all the constituent components of the surface layer of the intermediate transfer member (1) was about 70% by mass based on the total solid content in the coating material. This intermediate transfer member (1) is 350 mm in an environment of a temperature of 23 ° C. and a humidity of 65%.
The transfer surface of the intermediate transfer member (1) is placed in contact with an aluminum plate of × 200 mm, and a voltage of 1 kV is applied by a high voltage power supply between the aluminum cylinder and the aluminum plate on the inner surface of the intermediate transfer member (1) to supply power. 1kΩ connected in series with
The potential difference across the resistor was measured and converted to a current value, and the volume resistance of the intermediate transfer member (1) was calculated from the applied voltage and this current value, and was 5.0 × 10 ⁷ Ω.

Further, the average particle diameter used in this example is 0.
The 3 μm PTFE particles were 40% with respect to the comparative sample in the above-mentioned high lubricity judgment test.

Next, the contact angle and the slip resistance of the intermediate transfer member (1) were measured and obtained as follows.

The same coating material as that used for the intermediate transfer member (1) was used to form a coating film similar to that for the intermediate transfer member (1) on an aluminum sheet to obtain a coating layer sample sheet. The contact angle was measured using a goniometer-type contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.) and used as the contact angle of the intermediate transfer member coating layer. Further, the slip property of the intermediate transfer member coating layer was measured using a surface property measuring device: HEIDON-14DR (manufactured by Shinto Scientific Co., Ltd.). Specifically, a PET sheet is wrapped around an ASTM flat indenter of HEIDON-14DR to be an object to be measured, and a vertical load of 200 gf is applied between the coating layer sample sheet and the ASTM flat indenter to horizontally measure 100 mm / m.
in. PE when moving the sample sheet at the speed of
The slip resistance of the T sheet and the coating layer sample sheet was measured. At this time, the contact angle and the slip resistance are 112 respectively.
And was 83 g.

On the other hand, the magnetic toner was obtained as follows.

[Toner Production Example 1] 120 parts magnetic material (average particle size 0.22 μm) styrene-butyl acrylate-butyl maleic acid half ester copolymer (glass transition point Tg 60 ° C.) 100 parts Negative charging control Agent 4 parts ・ Low molecular weight polyolefin (release agent) 3 parts

The above materials were mixed in a blender,
Melted and kneaded in a twin-screw extruder heated to ℃, chilled kneaded material is roughly crushed with a hammer mill, coarsely crushed material is finely crushed with a jet mill, and the obtained finely pulverized material is subjected to multi-division classification using Coanda effect Strictly classifying with a machine, magnetic toner particles were obtained. The magnetic toner particles are surface-treated by thermo-mechanical impact force (treatment temperature 70 ° C.), and the obtained magnetic toner particles are subjected to a hydrophobic treatment with 2.0% by mass of silicone oil and hexamethyldisilazane. Dry silica having a diameter of 12 nm (BET specific surface area after treatment 120 m ² / g) and 0.
5% by mass of spherical silica (BET specific surface area 20 m ² / g,
A primary toner particle size of 0.1 μm) was added and mixed with a mixer to obtain a magnetic toner A. The weight average particle diameter of the obtained magnetic toner is 6.5 μm, the number average particle diameter is 5.3 μm, and SF-1 is 1.
40, SF-2 129, BET specific surface area 5.2 m ²
/ Cm ³ . The BET specific surface area of the toner particles was 1.65 m ² / cm ³ . Table 1 shows the physical properties of the obtained magnetic toner. In the present invention, the particle size was measured using a Coulter Counter Multisizer (manufactured by Coulter).

As the photoconductor, a 62φ aluminum cylinder was used as the support. Then, the layers having the constitutions shown in (1) to (4) were sequentially laminated by dip coating to prepare a photoconductor (1).

(1) Conductive coating layer: Mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin. Film thickness 15 μm.

(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. The film thickness is 0.6 μm.

(3) Charge generating layer: Mainly composed of an azo pigment having absorption in the long wavelength region dispersed in butyral resin. The film thickness is 0.6 μm.

(4) Charge transport layer: Mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight of 20,000 by Ostwald viscosity method) at a mass ratio of 8:10, and further polytetrafluoroethylene. 10% by mass of powder (particle size: 0.2 μm) was added to the total solid content and uniformly dispersed. The film thickness is 25 μm.

Next, the above-mentioned intermediate transfer body (1), magnetic toner A, and photoconductor (1) are mounted on the image forming apparatus shown in FIG. 7, and image formation is carried out under the following conditions to improve transfer efficiency. , Image quality, durability by repeated copying, etc. were evaluated and confirmed.

The intermediate transfer member cleaner 70 has a coating layer in which conductive tin oxide is dispersed in methoxymethylated nylon on the upper layer of urethane rubber in which conductive carbon is dispersed.
Using a medium resistance roller having a resistance of about 10 ⁸ Ω · cm,
A bias of +2.0 kV was applied during cleaning and used.

As the image forming conditions, laser exposure (600) was performed using the OPC drum of the photoconductor (1) as the electrostatic latent image carrier.
dark part potential VD = -600V, and light part potential V by
L = -100V. Further, the black developing device is used at the position of the developing device B in FIG. 7, and as a carrier for black toner, the layer thickness of the following constitution is about 7 μm, and the JIS center line average roughness (Ra) is 2.2 μm.
A resin sleeve of m was formed on a stainless steel cylinder having a diameter of 16φ whose surface was blasted to prepare a developing sleeve.

Phenolic resin 100 parts Graphite (particle size: about 7 μm) 90 parts Carbon black 10 parts

Then, the gap (between SD) between the photosensitive drum and the developing sleeve is 300 μm, and the developing magnetic pole is 80 mT (8
00 gauss) and a thickness of 1.0 m as a toner regulating member
Urethane rubber blade with a free length of 10 mm.
They were brought into contact with each other with a linear pressure of 7 N / m (15 g / cm). As a developing bias, a DC bias component Vdc = -450V, a superposed AC bias component Vp-p = 1200V, f = 2.
000 Hz was used.

As a photoconductor cleaning blade used for the photoconductor cleaner 14, the thickness is 2.0 mm and the free length is 8 m.
24.5 N / m (25 g
/ Cm) with a linear pressure. Further, the process speed was set to 94 mm / sec, the ratio Vt / V of the peripheral speed Vt of the developing sleeve to the peripheral speed V of the photoconductor was set to 1.5, and rotation was performed in the forward direction.

Photosensitive drum (1) which is the first image bearing member
The primary transfer efficiency from the intermediate transfer body (1) to the intermediate transfer body (1) is 96.5%, and the primary transfer efficiency from the intermediate transfer body (1) to the second image carrier 8
The secondary transfer efficiency to 0 g / cm ² paper was 97%. In this specification, the primary transfer efficiency and the secondary transfer efficiency are values obtained by the following formulas:

Then, the image print test was repeated. In addition, characters and fine lines without voids were obtained as the print image, and uniform image quality was obtained for solid images. Image quality similar to the initial one was obtained even after the durability test of 10,000 sheets, and the secondary transfer efficiency measured by the same method as above was 95%.
And almost no decrease was seen. When the surface of the intermediate transfer member after the durability test of 20,000 sheets was observed with a microscope, filming due to the toner did not occur at all, which was a good result. Table 2 shows the results.

Example 2 In Example 1, silicone resin particles having a particle size of 1 μm were used as the highly lubricating powder, and the ratio of the highly lubricating powder in the surface layer after drying and solidification was 60.
A durability test was conducted in the same manner as in Example 1 except that the content was changed to% by mass. A good full-color image was obtained as in Example 1. The results are shown in Table 2.

Example 3 A durability test was conducted in the same manner as in Example 1 except that fluorocarbon particles having a particle size of 0.8 μm were used as the highly lubricating powder. Example 1
A good full-color image was obtained as in the above. The results are shown in Table 2.

Example 4 In Example 1, silica particles having a particle diameter of 0.05 μm were used as the highly lubricating powder, and the ratio of the highly lubricating powder in the surface layer after drying and solidification was 30% by mass. A durability test was conducted in the same manner as in Example 1 except that Although the image quality is slightly different from that of Example 1, a good full-color image was obtained. The results are shown in Table 2.

Example 5 A durability test was conducted in the same manner as in Example 1 except that the proportion of the PTFE resin particles in the surface layer after drying and solidification was changed to 20% by mass. Although the transfer efficiency and the image quality were slightly inferior to those in Example 1, a full-color image with no practical problems was obtained. The results are shown in Table 2.

Comparative Example 1 A durability test was conducted in the same manner as in Example 1 except that the highly lubricating powder was not used. It was confirmed that the transfer efficiency was inferior from the initial stage, and there were problems in both image quality and durability after 10,000 sheets were used. The results are shown in Table 2.

Comparative Example 2 A durability test was conducted in the same manner as in Example 1 except that the proportion of the PTFE resin particles in the surface layer after drying and solidification in Example 1 was changed to 15% by mass. Transfer efficiency is inferior from the beginning, image quality after 10,000 sheets endurance,
It was confirmed that there was a problem with both durability. The results are shown in Table 2.
Shown in

(Examples 6 to 8) The following magnetic toner B,
Evaluation was performed in the same manner as in Example 1 using C and D. The results are shown in Table 2.

[Toner Production Example 2] 1. As inorganic fine powder
Dry silica having a primary particle size of 12 nm, which has been hydrophobized with 5% by mass of silicone oil and hexamethyldisilazane (B
ET specific surface area 120 m ² / g) and 0.5% by mass of spherical silica (BET specific surface area 5 m ² / g, primary particle size 1.0 μ
A magnetic toner B was obtained in the same manner as in Toner Production Example 1 except that m) was added. Table 1 shows the physical properties of the obtained magnetic toner.

[Toner Production Examples 3 and 4] Titanium oxide fine particles (BET specific surface area 100 m ² / g) having a primary particle size of about 20 nm, which were hydrophobized with silicone oil as inorganic fine powder,
Magnetic toners C and D were obtained in the same manner as in Toner Production Example 1 except that 1.2% by mass of alumina fine particles having a primary particle diameter of about 20 nm (BET specific surface area 90 m ² / g) were used.
Table 1 shows the physical properties of the obtained magnetic toner.

(Comparative Example 3) [Toner Production Example 5] -Magnetic substance (average particle size 0.22 µm) 80 parts-Styrene-butyl acrylate copolymer (glass transition point Tg 68 ° C) 100 parts Negative charge control agent 3 parts ・ Low molecular weight polyolefin (release agent) 4 parts

The above materials were mixed in a blender to obtain 130
Melted and kneaded in a twin-screw extruder heated to ℃, chilled kneaded material is roughly crushed with a hammer mill, coarsely crushed material is finely crushed with a jet mill, and the obtained finely pulverized material is subjected to multi-division classification using Coanda effect Strictly classifying with a machine, magnetic toner particles were obtained. Dry silica (BET specific surface area 100 m ² / BET having a primary particle size of about 16 nm that has been hydrophobized with 0.4% by mass of hexamethyldisilazane based on the obtained magnetic toner particles
g) was added and mixed by a mixer to obtain a magnetic toner E.
The weight average particle diameter of the obtained magnetic toner was 12 μm.
Table 1 shows the physical properties of the obtained magnetic toner.

The above magnetic toner E was used and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0153]

[Outside 1]

[0154]

[Outside 2]

[0155]

[Outside 3]

[0156]

As described above, according to the image forming method of the present invention, the following effects can be obtained. (1) High values can be obtained for both the primary transfer efficiency and the secondary transfer efficiency. (2) A good image can be obtained without the occurrence of a hollow image. (3) The residual toner after transfer is small, and the cleaning device can be downsized. (4) Since the transfer efficiency is high, the occurrence of filming due to durability can be suppressed. (5) The photoreceptor life can be extended without adversely affecting the organic photoreceptor.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a color image output device used in the present invention.

FIG. 2 is a schematic cross-sectional view of an example of an intermediate transfer member used in the present invention.

FIG. 3 is a schematic sectional view of an example of an intermediate transfer member used in the present invention.

FIG. 4 is a schematic cross-sectional view of an example of an intermediate transfer member used in the present invention.

FIG. 5 is a schematic diagram of a color image output device used in the present invention.

FIG. 6 is a diagram illustrating a hollow image.

FIG. 7 is a schematic view of a color image output device used in the present invention.

FIG. 8 is a graph showing the relationship between SF-1 and SF-2.

[Explanation of symbols]

 1 Photosensitive Drum 2 Primary Charger 3 Image Exposure 9 Paper Feed Cassette 14 Photosensitive Drum Cleaning Device 15 Fixing Device 20 Intermediate Transfer Body 21 Core Bar 22 Elastic Layer 24 Transfer Material 25 Transfer Roller 29 Bias Power Supply 35 Intermediate Transfer Body Cleaner 41 Magenta Color Developing device 42 Cyan color developing device 43 Yellow color developing device 44 Black color developing device 61 Bias power source 70 Cleaning roller 71 Residual toner 72 Toner image 100 Core metal 101 Elastic layer 102 Covering layer 103 Covering layer 104 Belt-shaped intermediate transfer member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takashi Kusaba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (20)

[Claims] 1. A surface layer of an intermediate transfer member in an image forming method, comprising transferring a toner image formed on a first image carrier to an intermediate transfer member and further transferring the toner image onto a second image carrier. Contains 20 to 80 mass% of highly lubricating powder,
Further, the toner is a toner having at least toner particles in which a colorant is dispersed in a binder resin and an inorganic fine powder, and the shape factor SF- of the toner measured by an image analyzer is
The value of 1 is 110 <SF-1 ≦ 180, the value of SF-2 is 1
10 <SF-2 ≦ 140, and {(SF-2) -10
The image forming method is characterized in that the value of (0)} / {(SF-1) -100)} is 1.0 or less. 2. An image forming method in which a toner image formed on a first image carrier is transferred to an intermediate transfer member and then further transferred to a second image carrier, wherein water on the surface of the intermediate transfer member is transferred. Has a contact angle of 60 ° or more and a slip resistance of 200g
And the value of the shape factor SF-1 measured by an image analyzer of the toner, which is the following, and the toner has at least toner particles in which a colorant is dispersed in a binder resin and an inorganic fine powder. Is 110 <SF-1 ≦ 180, SF−
The value of 2 is 110 <SF-2 ≦ 140, and {(SF-
2) -100)} / {(SF-1) -100)} is 1.0 or less. 3. The image forming method according to claim 1, wherein the intermediate transfer member is a roller having an elastic layer. 4. The image forming method according to claim 1, wherein the intermediate transfer member is a roller having an elastic layer and a coating layer. 5. The intermediate transfer member is a belt.
Alternatively, the image forming method described in 2. 6. The first image bearing member is a photosensitive drum having a photosensitive layer on a conductive rigid roller, and the intermediate transfer member is a rigid roller having an elastic layer, and is for electrophotography. The image forming method according to claim 1. 7. The image forming method according to claim 6, wherein the photosensitive drum has a surface layer containing fluororesin particles and is for electrophotography. 8. A specific surface area Sb (m ² / cm ³ ) per unit volume of the toner measured by the BET method,
The relationship of the specific surface area St (m ² / cm ³ ) per unit volume calculated from the weight average particle diameter when the toner is assumed to be a true sphere is 3.0 ≦ Sb / St ≦ 7.0 and Sb ≧ St × 1.
The image forming method according to claim 1, wherein the image forming method is 5 + 1.5. 9. At least one color toner of the toner is used in a magnetic material of 30 to 200 with respect to 100 parts by mass of the binder resin.
It is a magnetic toner containing parts by mass, and the value of SF-1 measured by an image analyzer of the toner is 120 ≦ SF-1 ≦ 1.
The image forming method according to claim 1, wherein the value of 60 and SF-2 is 115 ≦ SF-2 ≦ 140. 10. The {(SF-2) -10 of the toner
0)} / {(SF-1) -100)} is 0.20
The image forming method according to claim 1, wherein the image forming ratio is 0.90. 11. A charge amount per unit volume of the toner
Is 30 to 80 C / m ³The image according to claim 1 or 2.
Imaging method. 12. The inorganic fine powder contained in the toner is at least one kind of inorganic fine powder selected from titania, alumina, silica, or a double oxide thereof.
Alternatively, the image forming method described in 2. 13. The image forming method according to claim 1, wherein the inorganic fine powder contained in the toner is subjected to a hydrophobic treatment. 14. The image forming method according to claim 13, wherein the hydrophobic fine inorganic powder contained in the toner is at least treated with silicone oil. 15. The inorganic fine powder contained in the toner has a primary particle size of 30 nm or less, and the toner contains fine powder having a primary particle size of 50 nm or more.
The image forming method described. 16. The image forming method according to claim 15, wherein the fine powder of 50 nm or more contained in the toner is an inorganic fine powder. 17. The image forming method according to claim 15, wherein the fine powder of 50 nm or more contained in the toner is a resin fine powder. 18. The image forming method according to claim 15, wherein the fine powder of 50 nm or more contained in the toner is substantially spherical. 19. The specific surface area per volume of the toner particles measured by the BET method is 1.2 to 2.5 m ² /
The image forming method according to claim 1, wherein the image forming method is cm ³ . 20. 1 nm to 100 nm of the toner particles
The image forming method according to claim 1 or 2, wherein the cumulative pore area ratio of the pores is 60%, and the pore radius is 3.5 nm or less.