JPH08129273A - Image forming method - Google Patents

Abstract

PURPOSE: To obtain a good transfer characteristic over a long period of time and to prevent the deterioration in transferability due to embedding of inorg. particulates. CONSTITUTION: A photoreceptor is a cylindrical image carrying member having a diameter of >=70mm or a belt-like image carrying member having a radius of curvature of >=35mm in a transfer part. Toners are colored particles consisting of at least a resin externally added with inorg. particulates and coloring agents. These inorg. particulates have the maximal value of the number ratio respectively at the grain size xnm and ynm in a number-grain size distribution curve. The number ratio at a grain size of [(x+y)/2]nm is <=10number% and the value of X/Y is in a range of 0.5 to 2.0 when the number ratio of the inorg. particulates on the small grain size side having a grain size of [(x+y)/2]nm or below is defined as X number% and the number ratio of the inorg. particulates on the large grain size side having a grain size of [(x+y)/2]nm or above is defined as Y number% (where, 20<=x<=50, 3x<=y<=6x).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine or printer having a developing and transferring process using a developer for an electrostatic image comprising two components of toner (hereinafter also referred to as colored particles) and carrier. And the like regarding the image forming method.

[0002]

2. Description of the Related Art Conventionally, a copying machine using an electrophotographic system,
An image forming method such as a printer generally has a developing process, a charging process, a transferring process, a fixing process, and a cleaning process as basic processes. In particular, the charging and transfer processes are indispensable processes, a high electric field can be applied, and the corona discharge system is widely used because of excellent image uniformity. However, the corona discharge method has problems that a high voltage must be applied and is dangerous and that ozone is generated due to discharge and is harmful. From such a background, in recent years, the practical application of the contact charging method for the purpose of lowering the voltage and reducing ozone is being studied,
In particular, in the transfer step, a contact transfer method using a conductive roller (hereinafter also referred to as a transfer roller) is being studied. Since this roller transfer method does not use a discharge wire,
It also has an advantage that uneven transfer due to dirt on the discharge wire does not occur. However, on the other hand, in the roller transfer method, it is difficult to secure a sufficient transfer electric field and the transferability is poor, the transferability is easily affected by the developer characteristics, and image unevenness due to uneven pressing force occurs. There are problems etc. In particular, in images such as characters and lines, the toner is piled up in a mountain shape on the image portion, so that when the roller is pressed, a pressure difference is generated between the central portion and both end portions of the image, and the image is easily disturbed.

In recent years, multi-color or full-color image copying technology has been rapidly expanding, and the basic formation is divided into at least three basic colors such as yellow, magenta, cyan, and if necessary, black. It is done by overlapping them.

Therefore, the toner layer becomes thicker in the superposed portion, so that the transferability is deteriorated and the image disturbance at the time of transfer is more remarkable.

In order to reduce such problems, there is an increasing demand for improving the surface characteristics of the transfer roller and preventing transfer unevenness.

For example, JP-A 1-267676 discloses a method of applying a release agent to the surface of an image carrier before transfer, and JP-A-2-8684 discloses a method of applying a lubricant to the surface of the image carrier through a transfer roller. A method of applying is disclosed. However, when such a method is used, when the toner remaining on the image carrier is cleaned, a slip-through phenomenon occurs, which causes image stains. Further, when the image carrier is a photoconductor, the toner remaining due to the slip-through phenomenon may cause uneven charging. Further, due to the residual toner, the release agent and the lubricant cannot be continuously applied to the surface of the image bearing member for a long period of time, which may cause transfer unevenness in long-term use.

Further, generally, an external additive, that is, inorganic fine particles or the like is added to the toner for the purpose of improving the fluidity and controlling the charge amount.
(About ~ 50 nm) is used, the inorganic fine particles are embedded in the toner when the toner is subjected to uniform force by the mechanical action received in the developing device or when it is pressed by the transfer roller. However, there is also a problem that the transferability is deteriorated.

As described above, in the image forming method having the transfer step using the transfer roller, sufficient performance has not been obtained yet.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a good transfer characteristic for a long period of time in an image forming method having a transfer step by a conductive roller to which a voltage is applied, This is to prevent the transferability from being deteriorated due to the embedding of fine particles.

[0010]

The above objects of the present invention have been achieved by the following constitutions.

(1) A latent image formed on a photoconductor is developed with a developer consisting of at least toner and carrier to form a toner image on the photoconductor, and then a voltage is applied to the photoconductor so as to be electrically conductive. In an image forming method having a step of transferring by passing an image support between a roller and a photoconductor, the photoconductor has a cylindrical image carrier having a diameter of 70 mm or more, or a radius of curvature at a transfer portion is A belt-shaped image bearing member having a size of 35 mm or more, wherein the toner is colored particles comprising at least a resin externally adding inorganic fine particles and a colorant,
In the number-particle size distribution curve, the inorganic particles have a particle size of x nm
And y nm each have a maximum value of the number ratio, and the number ratio in the particle size [(x + y) / 2] nm is 10 number% or less, and the particle size is less than [(x + y) / 2] nm. The number ratio of the inorganic fine particles on the particle size side is X number%, [(x + y) /
2] An image forming method, wherein the value of X / Y is in the range of 0.5 to 2.0 when the number ratio of the inorganic fine particles on the large particle size side having a particle size of nm or more is Y number%. (However, 20
≦ x ≦ 50, 3x ≦ y ≦ 6x) (2) A latent image formed on the photoconductor is developed with a developer including at least a toner and a carrier to form a toner image on the photoconductor, and then an intermediate transfer body is formed. In the image forming method, there is a step of transferring the toner image by passing the image support between the conductive roller pressed against the intermediate transfer body to which a voltage is applied and the intermediate transfer body. The transfer member is a cylindrical image carrier having a diameter of 70 mm or more, or a belt-shaped image carrier having a radius of curvature of 35 mm or more in the transfer portion, and the toner contains at least a resin and a colorant to which inorganic fine particles are externally added. In the number-particle size distribution curve, the inorganic particles have a maximum value of the number ratio in each of the particle size xnm and ynm, and the particle size [(x + y) /
2] The number ratio in nm is 10 number% or less, and [(x
+ Y) / 2] nm, the number ratio of the inorganic fine particles on the small particle size side is X number%, and the number of inorganic fine particles on the large particle size side having a particle diameter of [(x + y) / 2] nm or more. The ratio is Y number%
And the value of X / Y is in the range of 0.5 to 2.0. (However, 20 ≦ x ≦ 50, 3x
≦ y ≦ 6x) The preferred embodiments of the present invention will be described below.

(3) The diameter of the conductive roller is 5 mm to 100 m
The image forming method described above, wherein m is m.

The image forming method of the present invention will be described in detail below.

The image forming method of the present invention is a transfer method using a conductive roller, in which a photoconductor having a relatively large diameter is used, and a specific number-particle size distribution (small particle size and large particle size) is used.
It is characterized by the use of inorganic fine particles having the following properties, whereby the transferability is improved, a suitable fluidity-imparting effect of the external additive and a superior effect on the burial resistance to the toner are remarkably excellent. It plays.

When the conductive transfer roller according to the present invention is used, a sufficient transfer electric field cannot be originally applied. Therefore, when the charge amount of the toner becomes large, the transfer electric field is easily canceled by the electric charge of the toner, so that the transferability is improved. Is reduced.
That is, the transferability changes greatly due to the change in the toner charge amount. Further, the embedding of the inorganic fine particles in the toner not only causes a sharp decrease in transferability but also causes a change in the charge amount of the toner.

In this situation, the diameter of the photosensitive member is
The radius of curvature of the cylindrical image carrier of 70 mm or more or the transfer part
When a belt-shaped image carrier having a size of 35 mm or more is used, transfer time is improved, and the transfer electric field and pressing force are uniform, so that transferability is improved.

If the cylindrical image bearing member is 70 mm or less and the belt-shaped image bearing member has a radius of curvature of 35 mm or less, the transfer time is short and the transfer rate is lowered and uneven transfer occurs.

The cylindrical image bearing member used in the present invention has a diameter
It is preferably 70 mm or more and 180 mm or less, and the radius of curvature of the belt-shaped image carrier used in the present invention is preferably 35 mm or more and 70 mm or less.

The belt-shaped image bearing member used in the present invention means a so-called belt-shaped image bearing member having an endless shape, and the image bearing member has a structure in which aluminum is formed on a belt-shaped support. It is obtained by forming an organic photoconductor or an inorganic photoconductor on the surface of a material coated or vapor-deposited with a conductive material such as. In a preferred embodiment of the present invention, an organic photoconductor is formed.

The intermediate transfer member used in the present invention is a cylindrical image bearing member having a diameter of 70 mm or more or a belt-shaped image bearing member having a radius of curvature of 35 mm or more at the transfer portion, like the above-mentioned photosensitive member.

The conductive transfer roller used in the present invention preferably has a diameter of 5 to 100 mm. By increasing the diameter of the conductive transfer roller, the transfer time is extended and the transfer efficiency is improved as in the case of the photoconductor. Further, since the transfer electric field is perpendicular to the transfer direction, there is an effect that image distortion due to the distortion of the transfer electric field is less likely to occur. However, on the other hand, since the pressing time becomes longer, image disturbance due to mechanical vibration or the like increases.
The range satisfying both of these is 5 to 100 mm, and sufficient transfer performance can be obtained without causing image distortion. If the diameter of the conductive transfer roller is 5 mm or less, a sufficient transfer time cannot be obtained, the transfer rate becomes low, and image distortion occurs. Also,
If it is 100 mm or more, the transfer time is too long and the image is disturbed due to contact. Here, a particularly preferable range is 20 to 50 mm.

Further, when the inorganic fine particles having the number-particle size distribution of the present invention are used, the inorganic fine particles on the small particle size side are suitable for imparting fluidity and are superior to the burial resistance of the inorganic fine particles on the large particle size side. At the same time, it has an effect of relieving the stress applied to the inorganic fine particles on the small particle size side.

Therefore, the time until burial is significantly increased, and the effect of imparting fluidity as an external additive is stably exhibited for a long period of time. Moreover, the physical adhesion between the toner and the photoconductor is reduced by the inorganic fine particles on the large particle size side, and the contact area and the number of contact points between the toner and the photoconductor due to the burying of the external additive can be made very small.

Therefore, as compared with the case where only the external additive having a small particle size is used, it is possible to dramatically stabilize the transfer rate and prevent the image unevenness due to the unevenness of the pressing force, and to obtain a good image for a long time. can get.

In the present invention, since the externally added inorganic fine particles are composed of a single type of inorganic fine particles, the large particle size inorganic fine particles are embedded in the toner and the small particle size inorganic fine particles are charged. Even if it starts to contribute to the property, the amount of charge given to the toner does not change.

In the number-particle size distribution curve of the inorganic fine particles of the present invention, the small particle size and the large particle size each have a maximum number ratio, and the number ratio in the intermediate particle size is 10 number% or less. Therefore, the effect of imparting fluidity and the effect of suppressing burial can be exhibited with a small amount of addition. Therefore, the release of inorganic fine particles due to the addition of an excessive amount is suppressed.

In the point that the inorganic fine particles externally added to the colored particles used in the present invention have a specific number-particle size distribution, as shown in FIG. 1, the particle size is x nm (however, 20 ≦ x ≦ 50) and ynm (however, 3x ≦ y ≦ 6x) has the maximum value of the number ratio, and the intermediate particle size is mnm [however, (x + y) /
It is necessary to have a “two-peak distribution” in which the number ratio in 2) is 10 number% or less.

Here, the number-particle size distribution of the inorganic fine particles of the present invention is, for example, an electron microscope photograph obtained by photographing each of 500 inorganic fine particles at a magnification of 20,000 using a scanning electron microscope. It was obtained by inputting "SPICCA" (manufactured by Nippon Avionics Co., Ltd.) and measuring the particle size of each inorganic fine particle.

Since the number-particle size distribution of the inorganic fine particles of the present invention is a two-peak distribution, the effect of improving the fluidity by the inorganic particles on the small particle side and the effect of suppressing the burial by the addition of the inorganic particles on the large particle side. Can be realized with a small addition amount.

In FIG. 1, the peak particle size x on the small particle size side is
The range is 20 to 50 nm. Peak particle size on the small particle size side is 20 nm
When it is less than the above, the inorganic fine particles are likely to be embedded in the colored particles due to a mechanical action. On the other hand, when the peak particle size on the small particle size side exceeds 50 nm, a large amount of the external additive having a large particle size is present, resulting in deterioration of fluidity. In addition, since the toner is not evenly attached to the toner surface, the charge amount distribution is widened, and the transfer rate is lowered and the image is uneven.

In FIG. 1, the peak particle size y on the large particle size side is in the range of 3 to 6 x nm. If the peak particle size on the large particle size side is less than 3 x nm, the difference in particle size between the small particle size side and the large particle size side is too small, and the number-particle size distribution curve of the inorganic particles is clear. It does not have a mountain distribution and cannot sufficiently exert the effect of improving fluidity and the effect of suppressing burial.

On the other hand, when the peak particle size of the large particle size exceeds 6 × nm, the effect of imparting fluidity by the inorganic particles on the small particle size side cannot be sufficiently exhibited.

In the present invention, the number ratio of silica fine particles on the small particle size side having a particle size of less than the above-mentioned intermediate particle size m is X.
%, The ratio X / Y is 0, where Y is the number ratio of the silica fine particles having a particle size of the intermediate particle size m or more on the large particle size side.
It must be in the range of 5 to 2.0. Also, X number%
And Y number% are determined by the area of the diagonal line of the number-particle size distribution curve.

The carrier used in the present invention may be any of iron powder, ferrite, magnetite, and resin-coated ones, but in view of uniformity of spikes and stress resistance, low magnetization, low specific gravity. A carrier having a small particle size or the like is desirable.

As the carrier core (magnetic particles) used in the present invention, magnetic particles having a specific gravity of 3 to 7 and a weight average diameter of 30 to 65 μm are used. For example, it is possible to preferably use ferrite particles, magnetite particles and the like within the above range.

As the coating resin for coating the carrier, fine particles of resin such as styrene resin, acrylic resin and styrene-acrylic resin can be used. The coating method is not particularly limited, and spray coating, MEC coating, multi-layer coating and the like can be used.

The toner used in the present invention will be described.

The colored particles constituting the toner used in the present invention include a binder resin, a colorant, and other additives (including the above-mentioned inorganic fine particles) which are optionally used, The average particle diameter is a volume average particle diameter of usually 1 to 30 μ.
m, preferably 5 to 20 μm. The binder resin that constitutes the toner is not particularly limited, and various conventionally known resins can be used. For example, styrene resin, acrylic resin, styrene / acrylic resin, polyester resin, etc. may be mentioned.

Examples of the additive include those composed of a single kind of inorganic compound, and by this, the change in the amount of charge imparted to the toner can be suppressed and the charging characteristics can be stabilized. it can.

The inorganic compound constituting the inorganic fine particles is not particularly limited, and compounds conventionally used as external additives for toners such as silica, alumina, titanium oxide, barium titanate and magnesium titanate. , Calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, magnesium oxide, antimony trioxide, zirconium oxide, silicon carbide and the like. Further, the inorganic compound may be subjected to a hydrophobic treatment. When the hydrophobic treatment is carried out, it is preferable to use a so-called coupling agent such as various titanium coupling agents and silane coupling agents, and further higher fatty acids such as aluminum stearate, zinc stearate and calcium stearate and their metals. It is also preferable to perform hydrophobic treatment with a salt.

As the titanium coupling agent for carrying out the hydrophobizing treatment, for example, tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, bis (dioctyl pyrophosphate).
Oxyacetate titanate and the like.

As the silane coupling agent, γ-
(2-aminoethyl) aminopropyltrimethoxysilane,
γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, Methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p- Methylphenyl trimethoxysilane etc. are mentioned.

Examples of the fatty acids include undecyl acid, lauric acid, tridecyl acid, dodecyl acid, myristic acid, palmitic acid, pentadecyl acid, stearic acid, heptadecyl acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid, etc. And long-chain fatty acids thereof, and examples of the metal salt thereof include salts with metals such as zinc, iron, magnesium, aluminum, calcium, sodium and lithium.

One of these compounds is used for the above-mentioned inorganic fine particles.
It is better to add up to 10% by weight to coat, preferably 3
~ 7% by weight. Also, these materials can be used in combination.

Furthermore, it is preferable that the inorganic fine particles having a two-peak distribution in the present invention are treated with the same surface treatment agent.

The colorant is not particularly limited, and various conventionally known materials can be used. For example, carbon black, nigrosine dye, etc. are used as the black toner, and C.I. is used as the pigment required for the yellow, magenta, and cyan toners.
I. Pigment Blue 15: 3, CI Pigment Blue 15,
CI Pigment Blue 15: 6, CI Pigment Blue 6
8, CI Pigment Red 48-3, CI Pigment Red 122, CI Pigment Red 212, CI Pigment Red 57-1, CI Pigment Yellow 17, CI Pigment Yellow 81, CI Pigment Yellow 154 and the like pigments are preferably used. be able to.

Other additives include, for example, salicylic acid derivatives, charge control agents such as azo metal complexes, low molecular weight polyolefins, and fixability improving agents such as carnauba wax.

The photoconductor used in the present invention may be a commonly used selenium photoconductor, amorphous silicon photoconductor, OPC photoconductor, or the like.

As the developing method in the present invention, a method in which the photoreceptor and the developer are developed in a non-contact manner is preferable. For example,
The developer is 300 ~ 6 on the developing sleeve by the layer regulation plate provided on the sleeve and the layer forming rod made of magnetic rods or non-magnetic rods.
The layer is regulated to a layer thickness of 00 μm and conveyed to the developing area. The gap between the developing sleeve and the photosensitive drum in the developing area is 0.4 to 1.0 mm, which is larger than the developer layer thickness.
By applying a developing bias in which an alternating electric field of kvp-p is superposed, it is possible to perform development without the developer coming into contact with the photoconductor.

As the transfer method in the present invention, a method in which a conductive roller to which a voltage is applied is pressed against a photosensitive member or an intermediate transfer member to transfer is preferable. For example, the transfer roller is movable with respect to the position of the peripheral surface of the photoconductor drum, and is placed in a pressure contact state when printing a single-color image, but is kept in a separated position while transferring during the formation of a color image. It is pressed only at times. In the apparatus used in the present invention, it is preferable to apply an applied voltage of a transfer current power source at +3 to 4 KVDC to perform constant current control of the transfer current. Also, a transfer roller of the type in which the roller surface is cleaned by a blade may be used.

The structure of the transfer roller according to the present invention will be described below. The transfer roller has a shaft body made of a stainless steel rod and a resin material such as polyurethane rubber, silicone rubber, styrene-butadiene copolymer elastomer, and olefin-based elastomer on the outer periphery thereof, and a cell size of 10 to 10
It is formed by a foaming type or open-cell type of about 0 μm, and further comprises an elastic portion as a charge-supplying conductive material in which an inorganic compound such as carbon black or an organic conductive agent is mixed as a conductivity-imparting agent in the resin material. There is.

Further, from the viewpoint of the cleaning property of the transfer roller surface, a surface coating layer portion may be provided on the transfer roller surface in a film thickness of 5 to 100 μm. Examples of the resin used for the surface coating layer include polyvinylidene fluoride (PVDF), polyamide 6 (nylon 6), polyamide 66 (nylon 66), polyethylene terephthalate (P
ET), perfluoroacrylate-based resins, polyester-based resins and the like.

The resistance of the transfer roller is 10 ² to 1
Preferably having 0 ¹⁰ Ω · cm, rubber hardness of the transfer roller, 60 ° or less as measured by a rubber hardness meter (JIS-K6301 Asker C scale hardness) is preferred

[0054]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 << Preparation of Sample >> -Manufacture of Carrier- A carrier was manufactured as follows.

Styrene / methyl methacrylate = 4/6 copolymer fine particles 60 g, specific gravity 5.0, weight average diameter 45 μm, 1000
The saturation magnetization is 62 when an Oersted external magnetic field is applied.
1940 g of Cu-Zn ferrite particles with emu / g was put into a high-speed stirring type mixer and mixed at a temperature of 30 ° C for 15 minutes.
After setting to ℃ and applying mechanical impact force repeatedly for 30 minutes,
It cooled and the carrier was produced.

-Production of Colored Particles- Colored particles were produced as follows.

100 parts of polyester resin, 10 parts of carbon black and 3 parts of polypropylene were mixed, kneaded, crushed,
The powder was classified to obtain a powder having an average particle size of 8.5 μm. This is colored particles 1
And In the same manufacturing method, yellow particles were used as coloring agents, colored particles 2 were used, magenta pigments were used as colored particles 3, and cyan pigments were used as colored particles 4.

-Production of Inorganic Fine Particles- Inorganic fine particles were produced as follows.

Various particle sizes were obtained by changing the water content and temperature conditions for the high temperature hydrolysis in the oxyhydrogen salt of silicon tetrachloride. Further, if necessary, the particles were classified as shown in Table 1 to adjust the particle size (number-particle size). Hexamethyldisilazane was used for the hydrophobic treatment of the silica fine particles. The obtained inorganic fine particles 1 to 14 (samples 1 to 14) are shown in Table 1 below.

[0061]

[Table 1]

(Peak particle diameter X) and (Peak particle diameter Y) in Table 1 are particle diameters that give the maximum values of the number ratio in the silica fine particles on the small particle diameter side and the silica fine particles on the large particle diameter side, respectively. In addition, (number ratio of intermediate particle size m) is
It is the value obtained from the number-particle size distribution curve of the number ratio of the hydrophobic silica fine particles having a particle size of [(x + y) / 2] nm.

Further, X / Y is the number ratio (X number%) of the silica fine particles on the small particle size side having a particle size of less than the intermediate particle size m.
And the number ratio (Y number%) of silica fine particles on the large particle size side having a particle size of the intermediate particle size m or more.

An example of the number-particle size distribution curve of the present invention (number-particle size distribution curve for the hydrophobic silica fine particles added to Sample 5) is shown in FIG.

The above number-particle size distribution curve is obtained from the particle size of 500 hydrophobic silica fine particles measured using an image analyzer "SPICCA" (manufactured by Japan Avionics Co., Ltd.).

-Preparation of Toner and Developer-Toner and developer were prepared as follows.

The inorganic fine particles shown in Table 1 were mixed with 100 parts of each of the above colored particles by a Henschel mixer to obtain a toner. Then 42 g of the obtained toner and carrier 558
and g were mixed for 20 minutes using a V-type mixer to prepare developers 1 to 14 for a live-copy test. Details are shown in Table 2 below.

[0068]

[Table 2]

<Evaluation device, conditions> Copier manufactured by Konica Corporation
The 9028 was modified as follows and a live-action test was conducted.

-Production of Remodeling Machine-1- The photosensitive member was a laminated type O having a diameter of 100 mm as a cylindrical image bearing member.
A PC drum was used.

(Development conditions) Photoconductor surface potential = -850V DC bias = -750V AC bias = 1.8kVp-p f = 8KHz Dsd = 500 μm Pressing control force = 10 gf / mm Pressing control rod = SUS416 (magnetic stainless steel) / Diameter 3
mm Development sleeve = 20 mm (transfer condition) Transfer current I = +20 μA constant current control.

Roller outer diameter 24 mm Elastic member Polyurethane resin Electric resistance value 5 ×
10 ⁴ Ω Nip width 2 mm, Nip pressure 300 g / cm ² or less. Fig. 3 shows modified machine-1.

FIG. 3 is a schematic vertical cross-sectional view of a modified machine No. 1 of the image forming apparatus suitable for applying the present invention, which is formed in the shape of a rotating cylinder and rotates in the direction of arrow A. The paper carrying unit 2 is arranged so that the paper is carried in the direction of the arrow and is formed by the image carrier 1 having axial direction and the transfer roller 3 having the roller cleaning blade 4.

-Manufacture of modified machine-2-Modified machine under the same conditions as modified machine-1 except that a belt drum having a radius of curvature of 50 mm was used as a belt-shaped image carrier.
No. 2 was produced.

FIG. 4 shows the modified machine-2.

In FIG. 4, an image forming apparatus is formed by using the belt-shaped image carrier 5 instead of the image carrier 1 formed in the rotating cylindrical shape in FIG.

-Preparation of Modified Machine-3: Modified Machine-3 was prepared under the same conditions as Modified Machine-1 except that an intermediate transfer member was provided.

FIG. 5 shows the modified machine-3.

An intermediate transfer member 6 having a diameter of 180 mm is arranged in the vicinity of the image carrier 1 formed in the shape of a rotating cylinder, and the transfer roller 3 is pressed against the intermediate transfer member 6, and the intermediate transfer member 6 is pressed. Is formed between the image carrier 1 and the transfer roller 3 to form a transfer portion.

<< Evaluation Items and Method >> Using the developer prepared as described above, samples 1 to 7 and 11 to 17 were subjected to a live-copy test using a modified machine No. 1 of copying machine 9028 manufactured by Konica Corporation. It was Samples 8 and 9 are modified machine No. 2 and sample, respectively.
The modified machine No. 3 was used for 10.

As a test, an actual copying test of 20,000 sheets was conducted, and the charge amount, transferability (transfer rate, transfer unevenness), image disorder (character dust), and image defect occurrence status were evaluated.

(Charge Amount) Charge amount μC / g (charge per unit weight) of the toner at the time of copying the first copy and the 20,000th copy at the start using a blow-off type charge measuring device. Was measured. It is preferable that the amount of change in charge is small.

(Transfer rate) A patch having an original density of 1.3 was developed, and after the first copy and the 20,000th copy at the start were transferred to plain paper, the mechanical operation was stopped before fixing, and The amount of toner of No. A was A, the amount of toner per unit area remaining on the photosensitive member was B, and [A / (A + B)] × 100 was taken as the transfer rate. A material having a small change in transfer rate is preferable.

(Transfer unevenness) A chart in which 20 lines each having a width of 200 μm and a length of 1 cm were arranged at intervals of 200 μm was copied and evaluated by the number of missing lines.

(Image Distortion) A chart in which five lines each having a width of 200 μm and a length of 1 cm are arranged at intervals of 200 μm is copied, and the dust situation of the portion is observed both visually and with a microscope. It was classified and judged.

A: No dust around the line is observed even with a microscope.

B: Although not visible visually, dust is observed in the periphery with a microscope.

C: Peripheral dust is visually observed.

D: Dust is so intense that it is difficult to distinguish between lines.

(Image Defect) Regarding the image defect caused by the scratch on the drum, the image is visually judged and vertical stripes or black spots,
The presence or absence of white spots was confirmed.

The evaluation results are shown in Table 3 below.

[0092]

[Table 3]

As is clear from Table 3, Samples 1 to 8 using the developer and the image bearing member of the present invention have a small change in charge amount, a small change in transfer rate, and no transfer unevenness. The transferability is excellent, and the outstanding effects of not disturbing an image and causing image defects are exhibited. Also, the sample
The sample No. 10 was evaluated by using the modified machine No. 3 in which the intermediate transfer member is arranged, and it has the same excellent effect as the samples 1-8. However, the comparative sample using the developer other than the present invention is
In none of the above evaluations, a satisfactory effect was obtained.

Example 2 Using the developer 1 of Sample 1, and changing the diameter of the transfer roller as shown in Table 4 below, a live-copy test was conducted in the same manner as in Example 1 using the modified machine-1. It was The evaluation results are shown in Table 4 below.

[0095]

[Table 4]

As is clear from Table 4, in comparison with Examples 18 and 19 in which the diameter of the transfer roller is outside the preferable range (5 to 100 mm), Sample 1 has a good transfer characteristic and a good transfer property. It can be seen that it is also excellent in preventing deterioration.

[0097]

By using the image forming method of the present invention, good transfer characteristics can be obtained for a long period of time, and further, the transferability can be prevented from deteriorating due to the burial of the inorganic fine particles.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a number-particle size distribution curve of the present invention.

FIG. 2 is a diagram showing an example of a number-particle size distribution curve of the present invention.

FIG. 3 is a vertical sectional view of a modified machine No. 1 of the copying machine 9028 of the present invention.

FIG. 4 is a vertical sectional view of a modified machine-2 of the copying machine 9028 of the present invention.

FIG. 5 is a vertical sectional view of a modified machine No. 3 of the copying machine 9028 of the present invention.

[Explanation of symbols]

 1 image carrier 2 paper transport unit 3 transfer roller 4 roller cleaning blade 5 belt-shaped image carrier 6 intermediate transfer member

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03G 15/08 507 L X 15/09 Z 15/14 101 G 15/16 21/00 350 (72) Inventor Keiko Ogawa 2970 Ishikawa-cho, Hachioji City, Tokyo Konica Stock Company

Claims (3)

[Claims] 1. A conductive roller which develops a latent image formed on a photoconductor with a developer including at least a toner and a carrier to form a toner image on the photoconductor and then presses the photoconductor to which a voltage is applied. In an image forming method including a step of transferring by passing an image support between a photoconductor and a photoconductor, the photoconductor has a cylindrical image carrier having a diameter of 70 mm or more, or a radius of curvature of 35 mm at a transfer portion. The above belt-shaped image bearing member, wherein the toner is a colored particle composed of at least a resin and an externally added inorganic fine particle, and the inorganic fine particle has a particle size of xnm and a particle size of xnm in a number-particle size distribution curve. Each ynm has a maximum value of the number ratio, and the particle size [(x + y) /
2] The number ratio in nm is 10 number% or less, and [(x
+ Y) / 2] nm, the number ratio of the inorganic fine particles on the small particle size side is X number%, and the number of inorganic fine particles on the large particle size side having a particle diameter of [(x + y) / 2] nm or more. Proportion is Y number%
And the value of X / Y is in the range of 0.5 to 2.0. (However, 20 ≦ x ≦ 50, 3x ≦ y ≦ 6x) 2. A latent image formed on a photoconductor is developed with a developer comprising at least a toner and a carrier to form a toner image on the photoconductor, and a toner image is transferred to an intermediate transfer body, and then a voltage is applied. In the image forming method having a step of transferring by passing the image support between the conductive roller pressed against the intermediate transfer body and the intermediate transfer body, the intermediate transfer body has a cylindrical shape with a diameter of 70 mm or more. Image carrier or
A belt-shaped image bearing member having a radius of curvature of 35 mm or more at the transfer portion, the toner being colored particles composed of at least a resin and externally added inorganic fine particles, and the inorganic fine particles being number-particles. In the diameter distribution curve, the particle size xnm and ynm each have a maximum value of the number ratio, and the particle size [(x +
y) / 2] The number ratio in nm is 10 number% or less,
Inorganic fine particles having a particle size of [(x + y) / 2] nm or more and having a particle size of [(x + y) / 2] nm or more are X number%. The image forming method is characterized in that the value X / Y is in the range of 0.5 to 2.0, where Y is the number ratio of Y. (However, 20 ≦ x ≦ 50, 3x ≦ y ≦ 6x) 3. The image forming method according to claim 1, wherein the conductive roller has a diameter of 5 mm to 100 mm.