JP2006171075A - Method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an image for preventing contamination of a photoreceptor due to deposition and sticking of a precipitative substance, derived from a transfer belt on the photoreceptor surface, preventing accompanying toner fusion or cleaning failure, as well as, reducing transfer drop due to toner aggregation at a contact site between the transfer belt and the photoreceptor. <P>SOLUTION: The method is carried out by using a photoreceptor having a conductive substrate, a photoconductive layer containing at least amorphous silicon, and a surface protective layer containing amorphous silicon and/or amorphous carbon and/or amorphous silicon nitride, on the conductive substrate. The infiltration amount x of an endless transfer belt, containing an elastic material to the photoreceptor surface at a contact site with the photoreceptor, is in the range of 0%<x≤5% with respect to the diameter d of the photoreceptor. The toner is a magnetic single-component toner containing at least a binder resin and a magnetic material, has a weight average diameter of 4 to 10 μm and has a specified amount of a surface magnetic material in the toner particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method used in an electrophotographic method, an electrostatic recording method, a magnetic recording method, and a toner jet recording method, and in particular, transfers a toner image on a photoconductor while conveying the transfer material. The present invention relates to an image forming method using an endless transfer conveying means to be transferred onto the image forming apparatus.

  As an image forming method conventionally used, many methods such as an electrophotographic method, an electrostatic recording method, a magnetic recording method, and a toner jet recording method are known. For example, there are electrophotographic methods described in Patent Documents 1 to 3, but generally, a photoconductive substance is used, and an electric latent image (electrostatic) is formed on the photoreceptor by various means. Latent image), and then developing the latent image with toner, and transferring the toner image onto a transfer material such as paper, if necessary, followed by heating, pressing, heating and pressing, or solvent vapor The transferred toner image is fixed and a copy is obtained. On the other hand, the toner remaining on the photosensitive member without being transferred is cleaned by various cleaning means, and the above-described process is repeated. Are known.

  In recent years, image forming apparatuses such as copying machines, laser beam printers, LED printers, facsimiles, and printing apparatuses using such image forming methods have become smaller, lighter, faster, and Therefore, higher reliability has been strictly pursued. On the other hand, the application fields of these output devices are expanding from the personal use to the professional use, and in particular, full-fledged as light printing (print-on-demand capable of high-mix low-volume printing; POD). Has begun to be used.

  Assuming light printing applications, higher capabilities are required than before in terms of reliability, print quality, durability, etc. Furthermore, for example, many transfer materials are widely used in the printing industry. It is necessary to correspond to the varieties. In this case, as one of the important issues, the transfer material having various characteristics (for example, material, thickness, size) can be stably transported and can be over and on the photoconductor without excess or deficiency. For example, the toner image may be transferred onto a transfer material.

  As a transfer means, a type using a corona discharge having a relatively simple structure is widely used. However, the transfer means using corona discharge has a narrow transfer material adsorbing area on the photosensitive member, which is a toner image carrier, and lacks in the stability of conveyance. In some cases, satisfactory results could not be obtained. Therefore, using a transfer medium that can run endlessly, such as an endless belt or a rotating cylinder, the transfer material is sandwiched and conveyed between the photosensitive member and an electric field having a polarity opposite to the charged polarity of the toner on the photosensitive member. Transfer means (hereinafter referred to as a transfer belt) for applying and electrostatically transferring a toner image on a photoreceptor onto a transfer material has been used. Since the transfer belt can hold and transfer the transfer material between the photosensitive member and the transfer belt, the transfer belt and the photosensitive member can be maintained stably regardless of the material, thickness and size of the transfer material. By adjusting the pressure contact force, even when the printing speed is high, it is difficult to cause a conveyance deviation and a transfer deviation, and it is possible to control the adsorption area of the transfer material to the photosensitive member, so that a high transfer quality can be maintained. Since such a transfer belt is rotationally driven in a state where tension is applied structurally, it is necessary to be superior in bending characteristics, tear strength characteristics, etc., and a rubber or elastomer type belt having elastic characteristics rather than a resin type belt Is mainly used.

  However, when an elastic material is used as the material of the transfer belt, a material such as a sulfur component added to accelerate vulcanization or a plasticizer added to impart plasticity is precipitated from this elastic material. . When these deposited substances migrate to and adhere to the surface of the photoreceptor, the photoreceptor may be deteriorated (chemical attack) or contaminated, leading to image defects. In addition, these precipitates attached to the surface of the photosensitive member serve as nuclei, and are fused (mainly surfaced as toner fusion) due to the filler and paper dust in the transfer material or a part of the toner and toner components being fixed. Occurrence of this phenomenon or further toner fusing may cause non-uniformity in the surface frictional resistance of the photoreceptor, resulting in poor cleaning. For example, in Patent Document 4, a block layer is provided on the surface layer of the transfer belt to prevent such deposits from adhering to the photoreceptor even when the precipitates are generated from the transfer belt. It is disclosed. Patent Document 5 discloses means for preventing contamination and deterioration of a photoreceptor by transferring a toner containing a large amount of an abrasive material to a transfer belt in advance and polishing the surface of the photoreceptor.

  According to the methods disclosed in these Patent Documents 4 and 5, although the effect of preventing the photoreceptor from being contaminated and deteriorated by the deposited material due to the transfer belt is effectively prevented under certain conditions, for example, light printing is performed. When the application is assumed, it is difficult to say that a sufficient effect can be obtained particularly in terms of durability and reliability during high-speed operation, and there is room for improvement in terms of complexity of the device and mechanism and cost reduction. Further, when an abrasive for polishing the photosensitive member is added to the toner, there may be an adverse effect on development characteristics, and further improvement is desired.

  In particular, when light printing applications are assumed, amorphous silicon photoconductors that can be used stably over a long period of time are preferably used because of their excellent wear resistance as photoconductors and high image quality. ing. When an amorphous silicon photoconductor is used, the deterioration of the photoconductor due to the deposited material due to the transfer belt is less likely to occur (becomes less susceptible), but occurs when the deposited material adheres to the surface of the amorphous photoconductor. The photoconductor contamination is a serious problem because it is very difficult to remove due to the high wear resistance of the amorphous silicon-based material.

  On the other hand, the transfer belt needs to convey and transfer the transfer material to and from the photoconductor, and supply a transfer current to the photoconductor side at the contact portion. ) In this case, and in this case, the toner image on the photoconductor is also pressurized, so that toner aggregation occurs and the toner aggregate tends to adhere to the surface of the photoconductor. There is a case where transfer is not performed at a strong portion (transfer defect) and an image defect (transfer missing) occurs.

  In order to solve such a problem, Patent Documents 6 to 7 add a plurality of specific additives to the toner, thereby preventing toner aggregation due to pressurization between the transfer belt and the photoconductor, and maintaining the transfer rate. Means are disclosed. However, the methods described in Patent Documents 6 to 7 are not sufficient when light printing applications are assumed, that is, a configuration in which a plurality of additives are externally added to a toner on the premise of high speed and high durability reliability. However, it is difficult to keep the balance between the powder characteristics and the charging characteristics of the toner, and the print quality may be deteriorated, and further improvement is required.

US Pat. No. 2,297,691 Japanese Patent Publication No.42-23910 Japanese Patent Publication No.43-24748 JP 2002-182481 A JP 2003-005581 A Japanese Patent Application Laid-Open No. 07-199681 JP 2003-098732 A

  An object of the present invention is to provide an image forming method that solves the above problems. That is, the present invention uses a photoconductor provided with a photoconductive layer containing at least amorphous silicon and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride, and developed by a reversal development method. In the image forming method for transferring the magnetic toner image on the transfer material conveyed on the elastic transfer belt to which the charge of the opposite polarity to the toner is applied, the deposited material caused by the transfer belt is a photosensitive member. Image that prevents contamination on the surface of the photoconductor, prevents toner fusing and cleaning defects that accompany this, and also reduces transfer dropout due to toner aggregation at the contact area between the transfer belt and photoconductor It is an object to provide a forming method.

  That is, the present invention is as follows.

(1) The present invention provides a photosensitive substrate comprising a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. The surface of the photoconductor is uniformly charged, an electrostatic latent image is formed on the photoconductor by exposure, and the electrostatic latent image is visualized by a reversal development method to form a toner image. In an image forming method for transferring a toner image in contact with a transfer material conveyed on an endless transfer conveying means to which a charge having a polarity opposite to the charge polarity of the toner is applied,
The endless transfer conveyance means is an endless transfer belt containing an elastic material, and is supported by at least two or more rollers installed on the upstream side and the downstream side in the conveyance direction of a portion in contact with the photoconductor, The penetration amount x with respect to the surface of the photoreceptor at the contact portion of the endless transfer belt containing an elastic material with the photoreceptor is in a range of 0% <x ≦ 5% of the diameter d of the photoreceptor,
The toner is a magnetic one-component toner containing at least a binder resin and a magnetic material, the toner has a weight average diameter of 4 to 10 μm, and the surface magnetic material in 20 mg of the toner particles is converted to 3 mol / l hydrochloric acid. The present invention relates to an image forming method characterized in that, in a solution extracted with 5 ml for 50 minutes, absorbance at 340 nm derived from the magnetic substance is 1.0 to 2.5.
(2) Further, according to the present invention, in the image forming method of (1), the toner has a dielectric loss tangent (tan δ) at 40 ° C. and a frequency of 1.0 × 10 ⁵ Hz of 3.0 × 10 ⁻³ to 1. The present invention relates to an image forming method characterized by being in a range of 0 × 10 ⁻² .
(3) Further, according to the present invention, in the image forming method of (1) or (2), the average diameter of the magnetic material is 0.1 to 0.4 μm, and the saturation magnetization of the toner is 12 to 60 Am ² / The present invention relates to an image forming method characterized in that kg and residual magnetization are 1.4 to 6.0 Am ² / kg.
(4) Further, according to the present invention, in the image forming method according to any one of (1) to (3), 70 to 500 free magnetic substances are present per 10,000 toner particles in the toner. The present invention relates to an image forming method.
(5) The present invention further relates to an image forming method according to any one of the above (1) to (4), wherein the toner is a positively chargeable toner.

  According to the present invention, a photoconductor developed with a reversal development method using a photoconductor comprising at least a photoconductive layer containing amorphous silicon and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. In an image forming method for transferring a magnetic toner image on a body by bringing it into contact with a transfer material conveyed on an elastic transfer belt to which a charge having a polarity opposite to that of the toner is applied, the magnetic one-component toner as described above is used. Thus, without using an additive such as an abrasive, it is possible to effectively prevent the contamination of the photoreceptor, which is a phenomenon of adhesion and fixation of the deposited substance due to the elastic transfer belt to the photoreceptor, and to prevent toner fusion and poor cleaning. At the same time, the transfer belt is removed due to toner aggregation caused by the pressure applied to the contact area between the transfer belt and the photosensitive member. It is possible to reduce the.

  Embodiments of the present invention will be described below.

  As mentioned above, endless transfer belts containing elastic materials, depending on the conditions of use, are added to give the sulfur component added to promote vulcanization and plasticity, although there are differences in the degree of use. The material such as plasticizer is deposited on the belt surface. This precipitation phenomenon is environmentally dependent and tends to become more prominent in a high temperature / high humidity environment. As an apparatus using a transfer belt containing an elastic material as a transfer conveying means, in addition to an apparatus in which the transfer belt is always pressed against the photosensitive member, the transfer belt is moved to the photosensitive member side only when the transferred transfer material is in contact with the photosensitive member. A device with a so-called separation / contact function that forms a nip by pressure contact is known, but even if a separation / contact function is provided, there is a deposit on the transfer belt surface due to an elastic material. In addition, it is inevitable from the structural point of view to fix the deposited substance on the photoreceptor.

  Therefore, in order to prevent image defects (toner fusing and poor cleaning) due to photoconductor degradation and photoconductor contamination caused by adhesion and fixation of the deposited substance on the surface of the photoconductor, a certain polishing effect is applied to the photoconductor. It is necessary to develop and clean the surface of the photoreceptor, but the present inventors have used an abrasive for polishing the surface of the photoreceptor by using a transfer belt containing an elastic material in combination with a specific magnetic toner. It has been found that the deposited substances from the transfer belt adhering to the surface of the photoreceptor can be effectively removed without adding to the toner.

  The magnetic toner used in the present invention exhibits an effective polishing action on the surface of the photoreceptor without sacrificing development characteristics or transfer characteristics by controlling the amount of the magnetic body exposed on the surface. Can do. In particular, even when using amorphous silicon photoconductors whose surface is difficult to clean because of high surface hardness, it is possible to perform normal operation without using an additive for the purpose of polishing and introducing a polishing device. Thus, an excellent polishing action on the surface of the photoreceptor can be obtained constantly, and contamination of the photoreceptor can be effectively prevented.

  That is, in a solution in which the toner has a weight average diameter of 4 to 10 μm and the surface magnetic substance in 20 mg of the toner particles is extracted with 5 ml of 3 mol / l hydrochloric acid for 50 minutes, the absorbance at 340 nm of absorption derived from the magnetic substance. When the value is in the range of 1.0 to 2.5, the polishing action on the surface of the photoreceptor is effectively expressed without affecting the development characteristics.

  In this case, it is preferable that the toner developed on the photoconductor is subjected to a specific pressure from the transfer belt side in the transfer process, and the transfer belt enters the photoconductor surface at the contact portion between the photoconductor and the transfer belt. By making the amount x in the range of 0% <x ≦ 5% of the photoreceptor diameter d, the polishing action is effectively exhibited on the photoreceptor surface.

  When the absorbance at 340 nm absorption derived from the magnetic material exceeds 2.5, the amount of the magnetic material exposed on the surface of the toner particles becomes very large, and the frequency of desorption of the magnetic material from the toner particles increases. Therefore, there are cases where an excessive polishing effect on the surface of the photoreceptor and the occurrence of uneven shaving are caused. In addition, excessive leakage of charge through the magnetic material exposed on the surface of the toner particles causes deterioration of the environmental characteristics of the toner. As a result, the image density decreases due to poor developability in a high humidity environment, and low humidity May increase fog in the environment. Also, the dispersion of the magnetic material in the toner particles is non-uniform, and there is a tendency for the absorbance to increase even when the magnetic material is unevenly distributed in the vicinity of the surface. In that case, the reliability may be lowered, and the developability may be lowered during long-term durability.

  On the other hand, when the absorbance at 340 nm absorption derived from the magnetic material is less than 1.0, the magnetic material is hardly exposed on the surface of the toner particles, and the polishing effect on the surface of the photoconductor is not sufficiently exhibited. In addition, since there are extremely few charge leak sites on the toner particle surface, the charge-up tendency becomes strong and the chargeability becomes unstable, so that the image density becomes unstable and fog increases in a low humidity environment. May be invited.

The absorbance in the present invention is the common logarithm of the reciprocal of the transmittance I / I ₀ which is the difference between the intensity I ₀ of the incident light and the intensity I of the transmitted light when light is incident on the sample cell. log (I ₀ / I)
It is represented by

  That is, the abundance of the magnetic material on the toner particle surface in the present invention is determined as follows.

<Measurement of amount of magnetic substance exposed on toner particle surface>
1) Weigh the toner (20 mg) precisely.
2) Put a sample in a sample bottle, add 5 ml of 3 mol / l hydrochloric acid, and leave it for 50 minutes.
3) After filtering the solution after standing, the filtrate can be measured using a spectrophotometer, for example, UV-3100PC manufactured by Shimadzu Corporation. At this time, 3 mol / l hydrochloric acid in which the toner is not dissolved is put in the control cell.

  The measurement conditions are as follows.

  Measurement conditions: scan speed (medium speed), slit width (0.5 nm), sampling pitch (2 nm), measurement range (600 to 250 nm)

  In the present invention, it is preferable that the toner developed on the photoconductor is pressed against the photoconductor side with a specific pressure from the transfer belt side, but the surface of the photoconductor and the transfer belt is in contact with the photoconductor surface. When the intrusion amount of the transfer belt exceeds 5% with respect to the photosensitive member diameter d, the controllability of the polishing action on the photosensitive member surface is deteriorated, and uneven shaving may occur. In addition, there is a strong tendency to generate transfer blur and transfer dropout in the transfer process.

  On the other hand, when the amount of penetration of the transfer belt is 0% or less with respect to the photoreceptor diameter d, the polishing effect on the photoreceptor surface may be insufficient.

  In the present invention, when the weight average diameter of the toner exceeds 10 μm, the polishing effect on the surface of the photosensitive member tends to be lowered even if the magnetic material is appropriately exposed on the surface of the toner particles. On the other hand, when the weight average diameter of the toner is less than 4 μm, the magnetic material released from the toner particles tends to increase, and the controllability of the polishing effect on the surface of the photoreceptor may be reduced, resulting in uneven shaving. Further, when the toner developed on the drum is pressed from the transfer belt side, the toner tends to aggregate, and the frequency of occurrence of transfer omission may increase.

  The weight average diameter of the toner in the present invention can be measured using a Coulter Counter TA-II type (Coulter) or a Coulter Multisizer (Coulter). As an electrolytic solution used in the measurement by these apparatuses, a 1% NaCl aqueous solution prepared using first grade sodium chloride, a commercially available electrolytic solution, for example, ISOTON R-II (manufactured by Coulter Scientific Japan) Can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant 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 is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement apparatus is used to measure the volume and number of toners of 2.00 μm or more using a 100 μm aperture as an aperture. Volume distribution and number distribution are calculated. Then, the mass-based weight average diameter (D4; the median value of each channel is a representative value for each channel) obtained from the volume distribution according to the present invention is obtained, and the cumulative percentage is obtained.

  As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Use 13 channels less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm.

Further, in the present invention, the dielectric loss tangent (tan δ) at 40 ° C. and a frequency of 1.0 × 10 ⁵ Hz of the toner is preferably in the range of 3.0 × 10 ^{−3 to} 1.0 × 10 ⁻² . By setting the dielectric loss tangent (tan δ) of the toner at 40 ° C. and a frequency of 1.0 × 10 ⁵ Hz to be in the range of 3.0 × 10 ^{−3 to} 1.0 × 10 ⁻² , magnetism in the toner particles is achieved. The dispersion state of the body can be improved, the controllability of the abundance of the magnetic body exposed on the surface of the toner particles is enhanced, and the magnetic properties as a magnetic toner are microscopically uniformed, so that Since the earing property of the magnetic toner developed on the body is more stable, the polishing action on the surface of the photoreceptor can be expressed more effectively. Further, for example, when the jumping development method is used, the toner rising property on the developing roller including the magnet roller is also stabilized, so that the toner charging characteristics are made more uniform and the developing characteristics are improved.

In the present invention, when the dielectric loss tangent of the toner exceeds 1.0 × 10 ⁻² , the magnetic substance is unevenly distributed in the toner particles, so that the magnetic characteristics of the toner are likely to be biased. In some cases, it is difficult to maintain uniform and stable toner appearance on the body, and magnetic particles having a relatively conductive property are unevenly distributed in the toner particles having high insulation properties. This results in non-uniformity, and as a result, in long-term durability, the developability may be lowered, such as a decrease in image density or an increase in fog.

On the other hand, when the dielectric loss tangent of the toner is less than 3.0 × 10 ⁻³ , the abundance of the magnetic material exposed to the toner particle surface decreases, and the polishing effect on the surface of the photoreceptor may not be exhibited. In addition, it becomes difficult to maintain the charging stability as the magnetic toner, which may cause a decrease in image density and an increase in fog in a low humidity environment.

The dielectric loss tangent (also referred to as loss tangent) of the toner of the present invention can be used as an index for evaluating the dispersibility of the magnetic substance in the toner particles. The dielectric loss tangent (tan δ) is obtained by measuring the dielectric constant (ε ′) and the dielectric loss factor (ε ″), calculating based on the measured values, and deriving as an index indicating whether the dispersibility is good or bad.
tan δ = ε ″ / ε ′
There is a relationship. In physical terms, ε ′ is energy stored per cycle, ε ″ is energy dissipated per cycle, and tan δ is characteristic of dielectric dispersion.

  In the present invention, the dielectric loss tangent of the toner can be determined as follows.

<How to find the dielectric loss tangent of toner>
1.0 g of toner is weighed, a load of 19,600 kPa (200 kgf / cm ² ) is formed into a pellet shape over 1 minute, and a disk having a diameter of 25 mm and a thickness of 2 mm or less (preferably 0.5 mm to 1.5 mm). Adjust to a solid sample. This sample is attached to ARES (Rheometric Scientific F.E.) equipped with a dielectric constant measuring jig (electrode) having a diameter of 25 mm, heated to a temperature of 80 ° C., and melt-fixed. Thereafter, the temperature is cooled to 40 ° C., a load of 0.49 to 1.96 N (50 to 200 g) is applied, the temperature is kept constant at 40 ° C., and the frequency is measured in the range of 1,000 Hz to 100,000 Hz.

  Using a 4284A Precision LCR meter (manufactured by Hewlett-Packard Company), after calibrating at a frequency of 1,000 Hz and 1 MHz, a dielectric loss tangent is calculated from a measured value of a complex dielectric constant at a frequency of 100,000 Hz (tan δ = ε ″ / ε ')can do.

Furthermore, in the present invention, the average diameter of the magnetic material is preferably 0.1 to 0.4 μm. The toner preferably has a saturation magnetization of 12 to 60 Am ² / kg, particularly preferably 15 to 50 Am ² / kg. It is preferable that the residual magnetization of the toner is 1.4~6.0Am ² / kg, in particular 1.4~5.0Am ² / kg is preferred. When the various characteristics of the toner are within the above ranges, the toner developed on the photoreceptor has appropriate spikes, so that there is appropriate exposure of the magnetic material on the toner particle surface, and from the transfer belt side. When receiving an appropriate pressure, the photosensitive member exhibits an effective polishing property on the surface of the photosensitive member, and also when the transfer material is pressed between the transfer material and the photosensitive member surface by a transfer belt in the transfer process. Since it has an appropriate sprouting property, the pressure contact force can be relaxed as if the spacer particles are present, and as a result, transfer defects and transfer skipping can be reduced.

  When the average diameter of the magnetic material exceeds 0.4 μm, the dispersion uniformity in the toner particles tends to become unstable. On the other hand, when the average diameter of the magnetic material is less than 0.1 μm, the magnetic properties are lowered and the color shifts to reddish brown, which is not practical for magnetic toner applications.

When the saturation magnetization of the toner exceeds 60 Am ² / kg and the residual magnetization exceeds 6.0 Am ² / kg, the dispersibility of the magnetic substance in the toner particles may be non-uniform, and the toner Since magnetic cohesion between particles appears, the polishing effect on the surface of the photoconductor may be reduced, and surface polishing may be uneven. In addition, transfer loss tends to occur during transfer. It can be seen.

On the other hand, when the saturation magnetization of the toner is less than 12 Am ² / kg, and when the residual magnetization is less than 1.4 Am ² / kg, the toner which is developed on the photoreceptor has insufficient earing property. In some cases, sufficient abrasiveness to the surface of the photoconductor may not be obtained, and when pressed from the transfer belt side, the effect of reducing the pressure contact force is not sufficiently exhibited, and the transfer is liable to occur. Appears.

  As described above, in the present invention, the magnetic properties of the toner are one of the important factors because it is necessary to develop an appropriate polishing property for the surface of the photoreceptor and to reduce the transfer loss. In the present invention, the coercive force Hc of the toner is preferably 5 kA / m or more, and particularly preferably 5 to 12 kA / m.

  In the present invention, the average diameter of the magnetic substance is selected from 300,000 times random magnetic pictures obtained by a transmission electron microscope, 300 magnetic substances are selected at random, and the diameter is measured by a digitizer. From this, it can be obtained as a number average. The diameter is the horizontal diameter.

In the present invention, the magnetic characteristics (coercive force Hc, saturation magnetization σs, residual magnetization σr) of the toner and the magnetic material are measured using an oscillating sample magnetometer VSM-3S-15 (manufactured by Toei Kogyo Co., Ltd.) and an external magnetic field. It can be measured as 7.96 × 10 ² kA / m (10 kOe).

  In the present invention, by controlling the abundance of the magnetic material exposed on the surface of the magnetic toner particles, to give the toner specific magnetic characteristics, and to give the toner developed on the photoconductor a suitable spike, In a situation where an arbitrary pressure is applied from the transfer belt side, a polishing effect is exerted on the surface of the photoconductor to prevent photoconductor deterioration and photoconductor surface contamination, and the photoconductor and the transfer material are pressed against each other. In the present invention, the surface of the photoreceptor can be more effectively controlled by controlling the amount of the magnetic material released from the toner particles. The polishing effect on the surface can be expressed. That is, in the toner of the present invention, it is preferable that 70 to 500 free magnetic materials are present per 10,000 toner particles, and in this range, the polishing action on the surface of the photoreceptor is more effectively expressed. The

  If more than 500 free magnetic materials are present per 10,000 toner particles, the polishing action on the surface of the photosensitive member may be excessively performed or uneven shaving may occur. Further, the free magnetic material adhering to the toner particles may act as a leakage point of the charge of the toner, and may reduce developability.

  On the other hand, when less than 70 free magnetic materials are present per 10,000 toner particles, the polishing action on the surface of the photoreceptor is slightly reduced, and non-uniformity appears in the chargeability of the toner. It may cause charge up in a low-humidity environment.

  In the present invention, the method for measuring the number of free magnetic materials is as follows.

  In the present invention, the number of free magnetic bodies can be measured using a particle analyzer (PT1000: manufactured by Yokogawa Electric Corporation). The measurement using a particle analyzer can be performed, for example, according to the method described in pages 65 to 68 of the Japan Hardcopy 97 paper collection. Specifically, the particle analyzer introduces fine particles such as toner one by one into the plasma, and can know the element of the luminescent material, the number of particles, and the particle size of the particles from the emission spectrum of the fine particles.

  For example, when toner particles are introduced into the plasma, light emission of carbon, which is a constituent element of the binder resin, and light emission of iron atoms in the magnetic material are observed for each toner particle. That is, the number of toner particles can be determined from the number of times of light emission. At that time, iron atoms emitted within 2.6 msec from light emission of carbon atoms were simultaneously emitted iron atoms, and light emission of iron atoms thereafter was light emission of iron atoms alone. Since the toner in the present invention is a magnetic toner and contains many magnetic materials, the fact that carbon atoms and iron atoms emit light at the same time means that the magnetic materials are dispersed in the toner particles. The light emission of iron atoms alone means that the magnetic substance is present free from the toner particles.

  Specifically, a toner sample which was allowed to stand overnight in an environment of a temperature of 23 ° C. and a humidity of 50% RH was measured in the above environment. Carbon atom (measurement wavelength 247.86 nm) is measured in channel 1, iron atom (measurement wavelength 239.56 nm, K factor 3.3376) is measured in channel 2, and the number of emitted carbon atoms is 1,000 to one in one scan. Sampling is performed so that the number is 1,400, and scanning is repeated until the total number of light emission of carbon atoms reaches 10,000 or more, and the number of light emission is integrated.

  At this time, in the distribution in which the number of light emission of the carbon element is on the vertical axis and the cube root voltage of the element is on the horizontal axis, the distribution is sampled so that it has a maximum and further has no valley. And measure. Based on this data, the noise cut level of all elements was set to 1.50 V, and the liberation rate of iron and iron compounds was calculated.

  In addition, materials other than inorganic compounds containing iron atoms, such as azo-based iron complexes that are charge control agents, may be contained in the toner, but such compounds contain organometallic compounds containing carbon atoms. If so, since light emission of carbon atoms in the organic substance is observed simultaneously with the iron atom, light emission of only the iron atom is not possible, and it is not counted as a free iron atom.

  In the present invention, the magnetic substance contained in the toner particles includes iron oxides such as magnetite, maghemite and ferrite; metals such as iron, cobalt and nickel or these metals and aluminum, cobalt, copper, lead, magnesium, Alloys of metals such as tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, or a mixture thereof are used. The inclusion is preferable from the viewpoints of controllability of magnetic properties and charge control on the toner. Among these magnetic materials, magnetic iron oxide is preferably used from the viewpoint of industrial application and cost merit, and particularly magnetite is preferably used. When magnetite is used, it is possible to control the magnetic characteristics, control the charging performance, or control the dispersibility in the resin by changing the shape of the magnetite or adding an arbitrary dopant. In the present invention, in combination with the transfer belt, the magnetic material exposed on the surface of the toner particles and the magnetic material released from the toner particles obtain a polishing action on the surface of the photoconductor. A shape having a ridge line or a corner such as an octahedron, a hexahedron, and a binuclear shape is preferable.

  In the present invention, the amount of the magnetic substance to be contained in the toner is preferably 10 to 200 parts by weight, more preferably 20 to 170 parts by weight, particularly 30 from the viewpoint of manifesting the effects of the present invention. -150 mass parts is preferable. The magnetic material can also be used as a colorant.

  In the present invention, as the binder resin contained in the toner particles, the following binder resins can be used.

  For example, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, or substituted products thereof; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers , Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol Resin, natural modification Enol 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 can be used. Among these, preferred binder resins include styrene copolymers or polyester resins. These may be used alone or in combination, but when mixed, at least a part of the resin to be mixed reacts with each other (chemically bonded). Are preferred).

  When the binder resin of the toner particles contained in the toner of the present invention is a styrene copolymer, examples of the comonomer for the styrene monomer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and acrylic acid. Double bonds such as dodecyl, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. Dicarboxylic acids having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like, and substituted products thereof; for example, vinyl chloride, vinyl acetate, benzoate Vinyl esters such as vinyl; ethylene-based olefins such as ethylene, propylene, butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; for example vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl Vinyl ethers such as ethers; esters of glycidyl alcohol and unsaturated carboxylic acids such as glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, β-methylglycidyl methacrylate, etc .; for example, allyl glycidyl ether And vinyl monomers such as unsaturated glycidyl ethers such as allyl β-methyl glycidyl ether; These comonomers are used alone or in combination of two or more.

  The styrenic polymer or styrenic copolymer used as the binder resin for the toner particles contained in the toner of the present invention may be cross-linked or used in admixture with other resins.

  As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butadiol dimethacrylate; And divinyl compounds such as aniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and compounds having three or more vinyl groups. These crosslinking agents are used alone or as a mixture.

  In the present invention, the toner particles can contain a charge control agent, whereby positive chargeability or negative chargeability can be maintained, and the chargeability can be controlled.

  The following substances are used for controlling the toner to be positively charged. For example, modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs of phosphonium salts thereof. Onium salts and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide) Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexane Such diorgano tin borate such Rusuzuboreto; guanidine compounds, imidazole compounds. These can be used alone or in combination of two or more. Among these, triphenylmethane compounds and quaternary ammonium salts whose counter ions are not halogen are preferably used.

  Further, there are the following substances that control the toner to be negatively charged. For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acid metal complexes, and aromatic dicarboxylic acid metal complexes. Other examples of controlling the toner to be negatively charged include aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol. .

  As a method for incorporating the charge control agent into the toner, there are a method of adding it inside the toner particles and a method of adding it externally, and either method may be used. The amount of these charge control agents used is determined by the toner production method including the type of binder resin, the presence or absence of other additives, and the dispersion method, and is not uniquely determined. It is used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin.

  In the present invention, the toner particles can contain a colorant, and examples of the colorant include any suitable pigment or dye. Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary to maintain the optical density of the fixed image, and the amount varies depending on the type of pigment, but is 0.1 to 20 parts by mass, preferably 0.2 to 100 parts by mass of the binder resin. An addition amount of -10 parts by weight is used.

  Further, a dye is further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and the amount used varies depending on the type of the dye, but is 0.1 to 20 parts by weight, preferably 0, based on 100 parts by weight of the binder resin. The addition amount of 3 to 10 parts by mass is good.

  In the present invention, it is preferable to contain waxes in order to give the toner particles releasability. Preferable wax is a wax having a melting point of 70 to 165 ° C. and a melt viscosity at 160 ° C. of 1000 mPa · s or less. Specific examples thereof include paraffin wax, microcrystalline wax, Fischer-Tropsch wax, montan wax, ethylene, Straight chain α-olefins such as propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1 and branches with terminal branches Examples include α-olefins and homopolymers or copolymers of olefins having different positions of these unsaturated groups. In addition, alcohol wax, fatty acid wax, ester wax, and natural wax can also be used. Furthermore, a wax made into a block copolymer with a vinyl monomer, a modified wax subjected to graft modification, or an oxidized wax subjected to an oxidation treatment may be used.

  These waxes may be added and mixed in any way in the production of the toner, but may be added and mixed in the polymer component in advance. When adding and mixing in advance in the polymer component, it is preferable to preliminarily dissolve the wax and the high molecular weight polymer in a solvent and then mix with the low molecular weight polymer solution when adjusting the polymer component. . Thereby, phase separation in a microscopic region is relaxed, reaggregation of high molecular weight components is controlled, and a good dispersion state with a low molecular weight polymer is obtained.

  Moreover, it is preferable that it is 0.1-20 mass parts with respect to 100 mass parts of resin, and, as for the addition amount of a wax, it is more preferable that it is 1-10 mass parts. Two or more kinds of waxes may be used in combination.

  The melting point of the wax is represented by the temperature of the main peak value in the endothermic curve measured according to ASTM D3418-8. For example, DSC-7 manufactured by PerkinElmer or DSC2920 (manufactured by TA Instruments Japan) Can be measured at a temperature elevation rate of 10 ° C./min. The melt viscosity of the wax can be measured, for example, using a cone plate type rotor (PK-1) with VT-500 manufactured by HAAKE.

In the present invention, silica fine powder is preferably externally added to the toner particles in order to improve charging stability, developability, fluidity, and durability. The silica fine powder used in the present invention has good results when the specific surface area by the BET method by nitrogen adsorption is 30 m ² / g or more, particularly in the range of 40 to 400 m ² / g. The silica fine powder is used in an amount of 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles. The specific surface area of the fine silica powder can be determined from the BET specific surface area multipoint method by adsorbing nitrogen gas to the sample surface using a normal measuring device such as a specific surface area measuring device Gemini 2375 (Shimadzu Corporation).

  In the present invention, the fine silica powder externally added to the toner particles may be a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane cups for the purpose of hydrophobization, chargeability control, etc., if necessary. It is also preferable that it is treated with a treating agent such as a ring agent, a silane compound having a functional group, other organosilicon compounds, or in combination with various treating agents.

  In the present invention, other external additives may be added to the toner particles as necessary. Examples of such external additives include charging aids, conductivity-imparting agents, fluidity-imparting agents, anti-caking agents, release agents at the time of heat roller fixing, lubricants, abrasives, etc. Examples include inorganic fine particles.

  For example, examples of the lubricant include polyethylene fluoride powder, zinc stearate powder, polyvinylidene fluoride powder, and the like. Among these, polyvinylidene fluoride powder is preferable. Examples of the abrasive include cerium oxide powder, silicon carbide powder, and strontium titanate powder. Of these, strontium titanate powder is preferable. Examples of the fluidity-imparting agent include titanium oxide powder and aluminum oxide powder, and among them, a hydrophobic one is preferable. Examples of the conductivity imparting agent include carbon black powder, zinc oxide powder, antimony oxide powder, and tin oxide powder. Furthermore, a small amount of reverse-polarity white fine particles and black fine particles can be used as a developability improver.

  In the present invention, the toner particles can be produced according to any known toner production method. For example, a binder resin, a magnetic material, other additives, etc. can be sufficiently obtained by a mixer such as a Henschel mixer or a ball mill. After mixing, the mixture is melt-kneaded using a heat kneader such as a heating roll, kneader, extruder, cooled and solidified, pulverized, and classified to obtain toner particles having a desired particle size distribution, and if necessary The desired additives can be sufficiently mixed by a mixer such as a Henschel mixer to obtain toner particles.

  As a mixer, for example, Henschel mixer (Mitsui Mining Co., Ltd.); Super mixer (Kawata Co., Ltd.); Ribocorn (Okawara Seisakusho Co., Ltd.); Nauter mixer, Turbulizer, Cyclomix (Hosokawa Micron Co., Ltd.); Spiral pin Mixer I (manufactured by Taiheiyo Kiko Co., Ltd.);

  As a kneading machine, for example, KRC kneader (manufactured by Kurimoto Iron Works); Bus co-kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine); TEX twin-screw kneader (manufactured by Nippon Steel Works) PCM kneading machine (Ikegai Iron Works); Three roll mill, mixing roll mill, kneader (Inoue Seisakusho); Needex (Mitsui Mining); MS pressure kneader, Nider Ruder (Moriyama Seisakusho) ); Banbury mixer (manufactured by Kobe Steel Co., Ltd.).

  Examples of the pulverizer include counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron); IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Industrial Co., Ltd.); cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); Max (manufactured by Nisso Engineering Co., Ltd.); SK Jet Oh Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries Co., Ltd.); It is done.

  Classifiers include, for example, a class seal, a micron classifier, a speck classifier (manufactured by Seishin Enterprise Co., Ltd.); a turbo classifier (manufactured by Nissin Engineering Co., Ltd.); a micron separator, a turboplex (ATP), a TSP separator (Hosokawa Micron Co. Elbow Jet (manufactured by Nippon Steel & Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Kogyo Co., Ltd.); Ultrasonic (Made by Sakae Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (Tokuju Kogakusha Co., Ltd.); Vibrasonic System (Made by Dalton); Soniclean (Made by Shinto Kogyo Co.); Turbo Screener (Turbo Industries Co., Ltd.) Micro shifter Sangyo Co., Ltd.); a circular vibration sieve, and the like.

  Below, with reference to drawings, an example of an embodiment in the present invention is further explained.

  FIG. 1 shows an example of this embodiment and shows a schematic diagram of a transfer process.

  The photoconductor 11 is provided with a photoconductive layer on a cylindrical conductive substrate. When a light printing application is assumed, a photoconductive layer containing amorphous silicon on the conductive substrate, and amorphous silicon and / or It is preferable in terms of high durability to use a photoconductor (amorphous silicon photoconductor in the present invention) provided with a surface protective layer containing amorphous carbon and / or amorphous silicon nitride. Amorphous silicon photoconductors, for example, have higher surface hardness, excellent polishing resistance, and superior environmental characteristics (that is, moisture resistance) compared to organic photoconductors. It is excellent in stability and high reliability during use, and is suitably used for POD applications. In particular, when the surface protective layer of the amorphous silicon photoconductor contains amorphous carbon, the releasability of the photoconductor surface is improved, so that it is easy to prevent adhesion and solidification of contaminants due to the transfer belt, and at the same time during transfer. This is preferable because occurrence of omission can be reduced. In addition, when the surface protective layer of the amorphous silicon photoconductor contains amorphous silicon nitride, it is easy to control the surface hardness of the photoconductor, which is preferable for suppressing unevenness of the photoconductor. However, the amorphous silicon photoconductor has a characteristic that it is difficult to maintain the surface of the photoconductor in a clean state constantly during actual operation because of its high polishing resistance. Therefore, when used in combination with a transfer belt containing an elastic material, there has been a major problem with respect to photoconductor contamination, which is a phenomenon in which a deposited substance due to the elastic transfer belt adheres and is fixed to the surface of the photoconductor. In the present invention, when used in combination with a specific magnetic one-component toner, it becomes possible to maintain the surface of the amorphous silicon photoconductor in a clean and steady state without using any abrasive. In addition, it has become possible to effectively reduce the transfer void due to the pressure applied between the photoconductor and the transfer belt, which has been a problem when using the transfer belt.

  In the present invention, a partial cross section of an example of a photoconductor provided with a conductive substrate, a photoconductive layer containing amorphous silicon on the substrate, and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. Is shown in FIG.

  As the conductive substrate 21 shown in FIG. 2, for example, aluminum (Al) is the most common, but chromium (Cr), molybdenum (Mo), gold (Au), indium (In), niobium (Nb), It is possible to use metals such as tellurium (Te), vanadium (V), titanium (Ti), platinum (Pt), lead (Pd), iron (Fe), and alloys thereof such as stainless steel. In addition, a transparent substrate such as glass or plastic, or an insulator such as ceramic is also made into a conductive substrate by conducting a conductive treatment on its surface, that is, the surface on the side where the photoconductive layer 23 is formed. Can do.

  Furthermore, in the present invention, the surface protective layer 2 made of amorphous silicon and / or amorphous silicon nitride is provided on the photoconductive layer 22.

  The photoconductive layer 22 may be organic or inorganic as long as it has photoconductivity. However, as the inorganic photoconductive layer, for example, an amorphous film in which silicon atoms contain hydrogen atoms and / or halogen atoms is used. It is preferable to use a quality material (hereinafter abbreviated as a-Si (H, X)) as a main component. Or inorganic materials, such as a-Se, can be combined suitably.

  Moreover, it is preferable that the photoconductive layer 22 contains an atom for controlling conductivity as required. The atoms that control conductivity may be uniformly distributed in the photoconductive layer 22 or may be unevenly distributed. Examples of the atoms that control conductivity include so-called impurities in the semiconductor field, atoms belonging to Group III of the periodic table that give p-type conduction characteristics (hereinafter abbreviated as “Group III atoms”), or n-type conduction. An atom belonging to Group V of the periodic table giving characteristics (hereinafter abbreviated as “Group V atom”) can be used. Specific examples of the group III atom include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). In particular, boron (B), aluminum (Al), and gallium. (Ga) is preferred. Specific examples of the group V atom include phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi), and phosphorus (P) and arsenic (As) are particularly preferable. By appropriately doping these impurities, the charging polarity of the amorphous photoreceptor can be determined.

  Further, in order to improve the photosensitive characteristics, the photoconductive layer 22 may have a plurality of layers such as a lower photoconductive layer 25 and an upper photoconductive layer 26. Although there is no limitation in particular as the film thickness of the photoconductive layer 22, about 15-50 micrometers is suitable from relationships, such as manufacturing cost.

  The surface protective layer 23 is a non-single crystal (preferably amorphous) material (a-SiC (H, X)) containing a silicon atom as a base and containing a carbon atom and, if necessary, a hydrogen atom and / or a halogen atom. A non-single crystal carbon (preferably amorphous carbon) (a-C (H, X)) containing a hydrogen atom and / or a halogen atom as necessary, a silicon atom as a parent, It is formed of a non-single crystal (preferably amorphous) material (a-SiN (H, X)) containing a nitrogen atom and, if necessary, a hydrogen atom and / or a halogen atom, or a combination thereof. Although there is no limitation in particular as the film thickness of the surface protective layer 23, about 0.05-2 micrometers is suitable from a viewpoint that what is necessary is just to exist at the minimum necessary for actual use. In addition, it is preferable to provide an interface layer (or antireflection layer) 27 in which the interface composition between the photoconductive layer 22 and the surface protective layer 23 is continuously changed, and to control the interface reflection in this portion. In addition, the surface of the conductive substrate 21 is preferably formed into a concavo-convex groove or dimple shape by cutting or the like. By adopting such a surface shape, it is possible to make it difficult to see the interference fringes caused by the reflection of the exposure light that has reached the surface of the conductive substrate 21, and the substrate of the film formed on the conductive substrate 21. The adhesion with 21 is also improved. Further, the shape of the conductive substrate may be as desired according to the driving method of the photosensitive member.

  Of course, in addition to these layers, various functional layers such as the charge injection blocking layer 24 as shown may be provided as necessary. For example, by providing the charge injection blocking layer 24 and appropriately selecting the dopant from group III atoms, group V atoms, etc., charge polarity control such as positive charge or negative charge becomes possible.

  In the embodiment of the present invention, the cylindrical amorphous silicon photoconductor is uniformly charged (primary charge; not shown) while being rotated in the direction of the arrow shown in FIG. An electrostatic latent image is formed (not shown), and development is performed with a magnetic one-component toner (not shown). As a development method, in order to perform normal development, a photosensitive portion corresponding to a non-image portion is used. On the contrary, when performing reversal development, it is necessary to expose a photosensitive portion corresponding to the image portion. That is, in forming an electrostatic latent image, it is necessary to select whether to expose a non-image area (back scan) or to expose an image area (image scan). With regard to these exposure methods, in principle, both methods can draw the same latent image, but the charging characteristics at the edge portion of the electrostatic latent image formed on the photosensitive member are substantially negligible. There is a tendency to produce a difference, and in particular, when developing an electrostatic latent image using a magnetic one-component toner having an arbitrary magnetic property, it is more sensitive to develop the electrostatic latent image formed by the image scanning method. A tendency to improve (stabilize) the toner's rising property on the body has been observed. Therefore, in the embodiment of the present invention, exposure by an image scanning method, that is, a reversal development system is more preferable.

  In the case of the reversal development method, when using a negatively chargeable amorphous silicon photoconductor (that is, an amorphous silicon photoconductor that holds a negative charge), a negatively chargeable toner is used, whereas a positively chargeable amorphous silicon photoconductor When the toner is used, a positively chargeable toner is used. There is no difference in image formation when using either of these, but when using a negatively charged amorphous silicon photoconductor, it is widely used as a primary charging means. When a corona discharge type charger is used, a large amount of ozone tends to be generated, and a large amount of discharge products are generated on the photoreceptor, which may significantly impede cleaning of the surface of the photoreceptor. Therefore, it is necessary to use, for example, a charge injection charger as a countermeasure. In this case, there is a tendency that the effect of removing the deposited substance due to the elastic transfer belt adhering to the photoreceptor is lowered. On the other hand, when a positively chargeable amorphous silicon photoconductor is used, ozone is generated in a relatively small amount even if a general corona discharge type primary charger is used. Therefore, in the present invention, it is preferable to use a system using a positively chargeable amorphous silicon photoconductor, that is, a positively chargeable toner.

  Next, the transfer process in the present invention will be described based on the schematic diagram of FIG.

  The endless elastic transfer belt 12 is supported by two or more rollers (two rollers, a driving roller 13, and a driven roller 14 in FIG. 1) arranged in parallel to each other in a direction substantially orthogonal to the transfer material conveyance direction. And is driven to rotate in the direction of the arrow by a drive motor (not shown). The endless elastic transfer belt 12 conveys the transfer material 17 in the direction of the arrow while the toner on the photoconductor 11 is pressed onto the transfer material 17 at the contact portion with the photoconductor 11 (that is, the transfer nip portion). Transcript under.

  In the present invention, the endless elastic transfer belt 12 is preferably pressed against the photoconductor side with an appropriate pressure from the endless elastic transfer belt 12 side at the contact portion with the photoconductor 11, and as shown in FIG. The penetration amount x of the endless elastic transfer belt 12 into the surface of the body 11 needs to be in the range of 0% <x ≦ 5% with respect to the diameter d of the photoconductor 11. The penetration amount x in this embodiment is shown in the examples (Table 2).

  The material of the endless elastic transfer belt 12 is preferably selected from materials having low hygroscopicity and stable resistance, such as chloroprene rubber, urethane rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber. In this case, the structure which has a base material is more preferable. The materials of the endless elastic transfer belt in this embodiment are shown in the examples (Table 2).

  The endless elastic transfer belt is accompanied by a bias roller 15 as transfer charge applying means for applying a transfer bias to apply a transfer charge, and a high voltage power source 16 for applying a voltage to the bias roller 15. The bias roller 15 is provided so as to contact the inside of the endless elastic transfer belt 12 at a position slightly downstream of the transfer nip portion in the rotation direction of the endless elastic transfer belt 12. The bias roller 15 constitutes a contact electrode for applying a charge having a polarity opposite to the charge polarity of the toner developed on the photoreceptor 11 to the endless elastic transfer belt. In the embodiment of the present invention, a bias of 6 kV in absolute value is applied on the side opposite to the charging polarity of the toner. The transfer charge applying means may be a charger using corona discharge or a brush-like charger. Further, the installation position of the transfer charge applying means is not limited to the downstream side in the rotational direction of the endless elastic transfer belt with respect to the transfer nip portion, and may be installed in the upstream direction.

  The schematic diagram of the transfer process shown in FIG. 1 has a structure in which the endless elastic transfer belt 12 is always pressed against the photoconductor 11 for the sake of simplicity of explanation. It is also preferable to provide a so-called separation / contact function that presses the transfer belt toward the photosensitive member only when the transfer material is in contact with the photosensitive member. In the present embodiment, the endless elastic transfer belt 12 is used as the photosensitive member except during the start-up operation and the stop-operation of the image forming apparatus (that is, while the process speed (= photosensitive member surface speed) of the apparatus main body is unstable). The pressure contact was made on the 11 side. In this embodiment, the peripheral speed of the endless elastic transfer belt is set to be the same as the peripheral speed of the photoreceptor.

<Example of toner particle production>
<Production Example 1 of Toner Particles>
Styrene-butyl acrylate-methacrylic acid-glycidyl methacrylate copolymer (71: 20: 3: 6, peak molecular weight 15,000, Mw: 120,000, Mn: 9000, Tg: 55 ° C.) 90 parts by mass Styrene -Butadiene copolymer (peak molecular weight 25,000, Mw: 270,000, Mn: 20,000)
10 parts by mass Magnetite A (octahedron, average particle size = 0.18 μm, coercive force Hc = 10.3 kA / m, saturation magnetization σs = 84.7 Am ² / kg, residual magnetization σr = 11.2 Am ² / kg)
90 parts by weight Triphenylmethane lake pigment (the following structural formula) 2 parts by weight Fischer-Tropsch wax (melting point 100 ° C.) 2 parts by weight Paraffin wax (melting point 73 ° C.) 3 parts by weight

  The above materials were sufficiently premixed with a Henschel mixer and then melt kneaded with a biaxial kneading extruder set at 110 ° C. The obtained kneaded product is cooled, coarsely pulverized with a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and further classified with a wind classifier. Toner particles (classified fine powder) 1 having a weight average particle diameter D4 = 7.1 μm were obtained. Hereinafter, the toner particles are also referred to as “No. 1 toner particles”.

100 parts by mass of toner particles (classified fine powder) 1 and amino modified silicone oil (amine equivalent 830, kinematic viscosity at 25 ° C.) per 100 parts by mass of silica fine powder (BET specific surface area 200 m ² / g) produced by a dry method 70 × 10 ⁻⁶ mm ² / s) 0.8 parts by mass of hydrophobized silica treated with 20 parts by mass, and externally mixed under any conditions using a Henschel mixer, sieved with a mesh having an aperture of 150 μm, and toner 1 was obtained. Hereinafter, it is also referred to as “No. 1 toner”.

The toner 1 has magnetic properties of Hc of 9.6 kA / m, σs of 39.8 Am ² / kg, σr of 3.6 Am ² / kg, absorbance at 340 nm of 2.0, and dielectric loss tangent (tan δ). ) Was 5.1 × 10 ⁻³ , and 210 free magnetic substances were present per 10,000 toner particles. Various characteristic values of the toner 1 are summarized in Table 1.

<Toner Particle Production Example 2>
Toner 2 having a weight average particle diameter D4 of 8.5 μm was obtained in the same manner as in Production Example 1 of toner particles, except that 90 parts by mass of magnetite A was changed to 140 parts by mass. Hereinafter, the toner particles are also referred to as “No. 2 toner”. Various characteristic values of Toner 2 are summarized in Table 1.

<Production Example 3 of Toner Particles>
In toner particle production example 1, 90 parts by mass of magnetite A was mixed with magnetite B (binuclear shape, average particle size = 0.17 μm, coercive force Hc = 7.2 kA / m, saturation magnetization σs = 89.9 Am ² / kg. Residual magnetization σr = 9.0 Am ² / kg): Toner 3 having a weight average particle diameter D4 = 7.6 μm was obtained in the same manner except that the content was changed to 140 parts by mass. Hereinafter, the toner particles are also referred to as “No. 3 toner”. Various characteristic values of Toner 3 are summarized in Table 1.

<Toner Particle Production Example 4>
In toner particle production example 1, 90 parts by mass of magnetite A was mixed with magnetite B (binuclear shape, average particle size = 0.17 μm, coercive force Hc = 7.2 kA / m, saturation magnetization σs = 89.9 Am ² / kg. Residual magnetization σr = 9.0 Am ² / kg): Toner 4 having a weight average particle diameter D4 = 9.2 μm was obtained in the same manner except that the mass was changed to 180 parts by mass. Hereinafter, the toner particles are also referred to as “No. 4 toner”. Various characteristic values of Toner 4 are summarized in Table 1.

<Toner Particle Production Example 5>
In Production Example 1 of toner particles, 90 parts by mass of magnetite A was mixed with magnetite C (octahedron, average particle size = 0.35 μm, coercive force Hc = 10.1 kA / m, saturation magnetization σs = 84.2 Am ² / kg. Residual magnetization σr = 14.1 Am ² / kg): Toner 5 having a weight average particle diameter D4 = 5.1 μm was obtained in the same manner except that the mass was changed to 90 parts by mass. Hereinafter, the toner particles are also referred to as “No. 5 toner”. Various characteristic values of Toner 5 are summarized in Table 1.

<Toner Particle Production Example 6>
In Production Example 1 of toner particles, 90 parts by mass of magnetite A was mixed with magnetite C (octahedron, average particle size = 0.35 μm, coercive force Hc = 10.1 kA / m, saturation magnetization σs = 84.2 Am ² / kg. , Residual magnetization σr = 14.1 Am ² / kg): 160 parts by mass, the melt kneading temperature in the biaxial kneading extruder is changed from 110 ° C. to 100 ° C. A toner 6 having a weight average particle diameter D4 = 3.7 μm was obtained in the same manner except that it was set higher (high-pressure pulverization). Hereinafter, the toner particles are also referred to as “No. 6 toner”. Various characteristic values of the toner 6 are summarized in Table 1.

<Toner Particle Production Example 7>
In toner particle production example 1, 90 parts by mass of magnetite A was mixed with magnetite D (binuclear shape, average particle size = 0.14 μm, coercive force Hc = 6.3 kA / m, saturation magnetization σs = 84.5 Am ² / kg. Residual magnetization σr = 7.1 Am ² / kg): Toner 7 having a weight average particle diameter D4 = 6.5 μm was obtained in the same manner except that the content was changed to 40 parts by mass. Hereinafter, the toner particles are also referred to as “No. 7 toner”. Various characteristic values of the toner 7 are summarized in Table 1.

<Production Example 8 of Toner Particles>
In toner particle production example 1, 90 parts by mass of magnetite A was mixed with magnetite D (binuclear shape, average particle size = 0.14 μm, coercive force Hc = 6.3 kA / m, saturation magnetization σs = 84.5 Am ² / kg. , Residual magnetization σr = 7.1 Am ² / kg): The weight average particle diameter was changed in the same manner except that the melt kneading temperature in the biaxial kneading extruder was changed from 110 ° C. to 90 ° C. A toner 8 with D4 = 7.2 μm was obtained. Hereinafter, the toner particles are also referred to as “No. 8 toner”. Various characteristic values of Toner 8 are summarized in Table 1.

<Production Example 9 of Toner Particles>
In toner particle production example 1, 90 parts by mass of magnetite A was mixed with magnetite D (binuclear shape, average particle size = 0.14 μm, coercive force Hc = 6.3 kA / m, saturation magnetization σs = 84.5 Am ² / kg. , Residual magnetization σr = 7.1 Am ² / kg): 90 parts by mass, the melt kneading temperature in the twin-screw kneading extruder was changed from 110 ° C. to 90 ° C., and superheated powder spheroidization after the pulverization step A toner 9 having a weight average particle diameter D4 = 7.0 μm was obtained in the same manner as in Production Example 1 except that the treatment step was added. Hereinafter, the toner particles are also referred to as “No. 9 toner”. Various characteristic values of the toner 9 are summarized in Table 1.

<Toner Particle Production Example 10>
In toner particle production example 1, 90 parts by mass of magnetite A was added to magnetite E (spherical, average particle size = 0.23 μm, coercive force Hc = 4.7 kA / m, saturation magnetization σs = 84.1 Am ² / kg, Residual magnetization [sigma] r = 5.0 Am < ² > / kg): Toner 10 having a weight average particle diameter D4 = 11.0 [mu] m was obtained in the same manner except for changing to 30 parts by mass. Hereinafter, the toner particles are also referred to as “No. 10 toner”. Various characteristic values of the toner 10 are summarized in Table 1.

<Production Example of Photoreceptor 1>
The photoreceptor 11 according to the present embodiment uses a cylindrical Al substrate having an outer diameter of 108 mm and a length of 358 mm, following the configuration shown in FIG. 2, and using a high-frequency plasma CVD (PCVD) method, the substrate temperature, gas type, and gas The amorphous silicon photoconductor of the present invention was obtained by appropriately adjusting the flow, the temperature in the reaction vessel, and the like.

  The following method is used for controlling the charging polarity of the photoconductor 11. For example, a charge injection blocking layer composed of an a-Si: H film doped with phosphorus (P) in hydrogenated a-Si (a-Si: H), and light composed of an undoped a-Si: H film A negatively chargeable a-Si photoconductor can be obtained by providing an electrically conductive layer and an interface layer composed of an a-Si: H film doped with boron (B) on a conductive substrate. On the other hand, for example, a charge injection blocking layer composed of an a-Si: H film doped with boron (B), a photoconductive layer composed of an a-Si: H film doped with boron (B), silicon and carbon A positively chargeable a-Si photoconductor can be obtained by providing a surface protective layer composed of a silicon film (a-SiC: H) made of a conductive substrate on a conductive substrate.

  Based on the above production method, a positively chargeable photoreceptor 1 having a photoconductive layer containing amorphous silicon and a surface protective layer containing amorphous silicon carbide (a-SiC: H) on a cylindrical Al substrate was produced.

<Production Example of Photoreceptor 2>
A cylindrical Al substrate having an outer diameter of 108 mm and a length of 358 mm is used, and the substrate temperature, gas type, gas flow, temperature in the reaction vessel, etc. are appropriately adjusted by high-frequency plasma CVD (PCVD) method. A positively chargeable photoconductor 2 comprising a photoconductive layer containing silicon and a surface protective layer containing amorphous carbon (aC: H) containing carbon atoms as a base and containing carbon atoms was produced.

<Example of production of photoconductor 3>
A cylindrical Al substrate having an outer diameter of 108 mm and a length of 358 mm is used, and the substrate temperature, gas type, gas flow, temperature in the reaction vessel, etc. are appropriately adjusted by high-frequency plasma CVD (PCVD) method. A positively chargeable photoreceptor 3 having a photoconductive layer containing silicon and a surface protective layer containing amorphous silicon nitride (a-SiN: H) was produced.

  The machine used for evaluation in this example is a peripheral portion of a transfer device of a commercially available digital copying machine iR105 (105 cpm, a-Si photosensitive drum mounted, magnetic one-component reversal jumping development method, manufactured by Canon Inc.). The transfer belt type shown in 1 is modified and replaced with the amorphous silicon photoconductor manufactured in this embodiment, and the process speed of the machine body (= the peripheral speed of the photoconductor drum) is changed to 600 mm / sec and 500 mm / sec. It was modified and used as possible.

  In this embodiment, the developing process uses a developing device mounted on the iR 105, and adopts a method in which the electrostatic latent image on the photoconductor 11 is reversely developed by a magnetic one-component jumping developing method. As development conditions, a rotatable developing roller including a magnet roller is coated with the magnetic toner of the present invention on a thin layer, a DC bias of +300 V, a Vpp = 1.2 kV, a frequency of 2.7 kHz, a duty wave of 50% rectangular wave. An AC bias was applied. As the setting conditions of the developing device, the distance between the magnetic doctor blade and the developing roller was 210 to 220 μm, the distance from the developing roller to the a-Si photosensitive drum surface was set to 190 to 210 μm, and the non-contact developing condition was set. . The surface potential of the photosensitive drum was developed by setting VD to +380 to +420 V and VL to +30 to +50 V.

[Example 1]
In the setting of the evaluation machine, the photosensitive member 1 is used, the transfer belt material is chloroprene rubber, the transfer belt intrusion amount x with respect to the photosensitive member is set to 2%, and the process speed of the evaluation machine is 600 mm / sec. The following evaluation was performed on toner 1.

  23 ° C / 50% RH environment (shown as NN in Table 2), 23 ° C / 5% RH environment (shown as NL in Table 2), and 32 ° C / 90% RH environment (shown as HH in Table 2) Then, a durability test was performed in which a character image with an image ratio of 6% was printed continuously on both sides of each A300 sheet by A4 horizontal feeding. During or after each durability test, photoconductor contamination, poor cleaning, and on the photoconductor Each of the following items was evaluated: earing state of the developed toner, transfer omission, transfer deviation, image density, and image fogging, and after the endurance test through each environment, the unevenness of the surface of the photoreceptor was evaluated. The evaluation was performed according to the following indicators.

<Evaluation of surface contamination of amorphous silicon photoconductor>
As a method for evaluating the photoreceptor contamination, which is a phenomenon in which the deposited substance resulting from the elastic transfer belt adheres and is fixed to the surface of the photoreceptor, the evaluation was based on fusion that appears as an image defect on the printed transfer material. At the end of the durability test in each environment, a solid black image of A3 size was printed, and the phenomenon appearing as a white image defect was evaluated, and classified into the following evaluation ranks. After the evaluation in each environment, the surface of the photoconductor was carefully cleaned to remove the fused material, and later prepared for a test in the next environment.
A: No fusing B: Partial fusing C: Full fusing

<Evaluation of defective cleaning>
The printed surface during the endurance test in each environment was regularly observed, evaluated based on streak-like or smudged image defects appearing on the printed surface as defective cleaning, and classified into the following evaluation ranks.
A: No cleaning failure B; Slight cleaning failure occurs intermittently C; Cleaning failure continues

<Evaluation of uneven shaving of amorphous silicon photoconductor surface>
When uneven shaving occurs on the surface of the photoconductor, a difference occurs in the chargeability of the photoconductor surface, and as a result, it appears as an image density difference when a halftone image is printed. Therefore, in this embodiment, the surface protection layer film is formed on the surface of the photoconductor drum corresponding to the density difference of the halftone image of the photoconductor drum after the endurance test in all environments (that is, after endurance of 900,000 sheets). The thickness was measured to determine the amount of scraping on the drum surface and classified into the following evaluation ranks. In addition, the film thickness of the surface protective layer was measured by interference of light using SPECTOR MULYI CHANNEL PHOTO DETECTOR (MCPD) manufactured by Otsuka Electronics Co., Ltd.
A: Abrasion amount difference is less than 40 nm B; Abrasion amount difference is 40 nm or more and less than 70 nm C; Abrasion amount difference is 70 nm or more

<Evaluation of rising state of toner developed on photoreceptor>
At the end of the durability test in each environment, in the transfer process described in this embodiment, development is performed with the elastic transfer belt separated from the photosensitive member (using the separation / contact function), and immediately after that, the photosensitive member is stopped suddenly. The photosensitive member was taken out after sufficient charge relaxation for a long time, and the toner image on the electrostatic latent image was observed with a microscope and classified into the following evaluation ranks.
A; toner spikes are confirmed on the electrostatic latent image B; toner spikes are confirmed on at least a part of the electrostatic latent image C; toner spikes are not confirmed on the electrostatic latent image

<Evaluation of transfer omission and transfer deviation>
At the end of the endurance test in each environment, both vertical and horizontal lines were printed on a 160 g / m ² (A4) paper on both sides of an 8 mm grid pattern with 200 μm, 500 μm, 1 mm, and 2 mm line widths repeated. Arbitrary 10 spots of the face print were observed visually and with a magnifying glass (× 30) and classified into the following evaluation ranks.

<Transfer missing>
A: No transfer omission B: Transfer omission is confirmed in part of the field of view by observation using a 30 × magnifier C: Transfer omission is confirmed visually

<Transfer deviation>
A: No transfer deviation B; Transfer deviation is confirmed at a part of the rear end of the image C: Slight transfer deviation is confirmed at a part of the entire image

<Evaluation of image density>
With respect to the image at the end of the endurance test, the reflection density was measured using an SPI filter using a Macbeth reflection densitometer (manufactured by Macbeth), and classified into the following evaluation ranks.
A: 1.45 or more B; 1.40 or more but less than 1.45 C; 1.20 or more but less than 1.40 D; 0.8 or more but less than 1.20 E; less than 0.8

<Evaluation of image fog>
Using a reflection densitometer (reflectometer model TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.)) for the image at the end of the durability test, the average value of the reflection density on the white background of the printed image is Ds, and transfer before image transfer When the reflection density average value of the paper was Dr, Ds-Dr was measured as a fog value and classified into the following evaluation ranks.
A: 0 or more and less than 0.5 B; 0.5 or more and less than 1.0 C; 1.0 or more and less than 1.5 D; 1.5 or more and less than 2.0 E; 2.0 or more

  Table 2 summarizes the evaluation machine settings and evaluation results.

[Examples 2 to 6]
In the setting of the evaluation machine, the photosensitive member No. The toner 2 to 5 and the toner 7 were evaluated in the same manner as in Example 1 with the transfer belt material, the transfer belt penetration amount x with respect to the photoconductor, and the process speed of the evaluation machine as set values shown in Table 2. .

  Table 2 summarizes the evaluation machine settings and evaluation results.

[Comparative Examples 1-4]
In the setting of the evaluation machine, the photosensitive member No. The toner 6 and the toners 8 to 10 were evaluated in the same manner as in Example 1 with the transfer belt material, the transfer belt penetration amount x with respect to the photoconductor, and the process speed of the evaluation machine as set values shown in Table 2. .

  Table 2 summarizes the evaluation machine settings and evaluation results.

It is the schematic of a transfer process. 2 is a partial cross-sectional view of an example of a photoreceptor including a conductive substrate, a photoconductive layer containing amorphous silicon on the substrate, and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Photoconductor 12 Endless elastic transfer belt 13 Driving roller 14 Driven roller 15 Bias roller 16 High voltage power supply 17 Transfer material 21 Conductive substrate 22 Photoconductive layer 23 Surface protective layer 24 Charge injection blocking layer 25 Lower photoconductive layer 26 Upper photoconductive Layer 27 Antireflection layer or interface layer

Claims (5)

Using a photoconductor comprising a conductive substrate, a photoconductive layer containing at least amorphous silicon and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride on the conductive substrate, the surface of the photoconductor Is uniformly charged, an electrostatic latent image is formed on the photosensitive member by exposure, the electrostatic latent image is visualized by a reversal development method to form a toner image, and the toner image is charged with the charge polarity of the toner. In the image forming method of transferring by contacting a transfer material conveyed on an endless transfer conveying means to which a charge of reverse polarity is applied,
The endless transfer conveyance means is an endless transfer belt containing an elastic material, and is supported by at least two or more rollers installed on the upstream side and the downstream side in the conveyance direction of a portion in contact with the photoconductor, The intrusion amount x of the endless transfer belt with respect to the surface of the photoconductor at the contact portion with the photoconductor is in a range of 0% <x ≦ 5% of the photoconductor diameter d,
The toner is a magnetic one-component toner containing at least a binder resin and a magnetic material, the toner has a weight average diameter of 4 to 10 μm, and the surface magnetic material in 20 mg of the toner particles is converted to 3 mol / l hydrochloric acid. An image forming method, wherein the absorbance at 340 nm derived from the magnetic substance is 1.0 to 2.5 in a solution extracted with 5 ml for 50 minutes. 2. The dielectric loss tangent (tan δ) of the toner at 40 ° C. and a frequency of 1.0 × 10 ⁵ Hz is in a range of 3.0 × 10 ^{−3 to} 1.0 × 10 ^−2. The image forming method described. The average diameter of the magnetic material is 0.1 to 0.4 μm, the saturation magnetization of the toner is 12 to 60 Am ² / kg, and the residual magnetization is 1.4 to 6.0 Am ² / kg. The image forming method according to claim 1 or 2.   The image forming method according to any one of claims 1 to 3, wherein the toner contains 70 to 500 free magnetic substances per 10,000 toner particles.   The image forming method according to claim 1, wherein the toner is a positively chargeable toner.

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