JP2008158429A - Development method, image forming method, and image forming apparatus - Google Patents

Abstract

An image forming method and an image forming apparatus capable of stably forming a high-resolution image with toner having a small particle diameter.
A toner having a volume average particle size of 2 μm or more and less than 4 μm and a ratio of the volume average particle size to the number average particle size of 1 to 1.1 is measured in the axial direction of a toner conveying surface of a developing roller 101. As the spacer 106 for setting the developing gap G in contact with the photoreceptor 61 on the outer side, a material that swells due to moisture absorption is larger than the surface constituting member of the developing roller, and an AC superimposed voltage is applied to the photoreceptor. The photosensitive member exposure 200 is a lens array in which light emitted from a plurality of light emitting elements corresponding to one lens forms an image on the photosensitive member, and the lens array extends in the main scanning direction. An image forming method and an image forming apparatus for forming an image by forming an exposure spot having a diameter of 15 to 40 μm on a photoconductor using a plurality of rows.
[Selection] Figure 2

Description

  The present invention relates to an image forming apparatus that develops an electrostatic latent image, such as electrophotography, a dry copying machine, a printer, and a facsimile machine, and more particularly, to a developing method, an image forming method, and an image forming apparatus capable of forming a high-resolution image.

Toner used in an image forming apparatus that develops an electrostatic latent image has been made to have a smaller particle size in order to increase image resolution and reduce toner consumption.
However, toner having a particle size of less than 4 μm has a low bulk density and is difficult to handle, and is difficult to be compressed and conveyed to a developing roller. In addition, there is a problem that leakage from the slight gap of the seal portion of the toner cartridge or the like is likely to occur to the outside.
Furthermore, when forming images of the same size, it is necessary to efficiently convey a larger number of toners from the developing roll to the photoconductor than in the case of toner having a large particle size. there were.

There is known a non-contact jumping development system in which a developing roll is provided with a gap between the photosensitive member and a developing voltage is applied for development.
However, even in the case of such a developing method, there is a problem in obtaining a desired image density because the charge amount is not sufficient with a small particle diameter toner having a particle diameter of 4 μm or less. In non-contact development, it has been difficult to maintain the development gap for a long time.

On the other hand, when image formation is performed with a small particle diameter toner, the spot diameter of the light beam to be exposed to be irradiated onto the photoreceptor is required to be 15 to 40 μm.
However, in the conventional method of scanning the surface of the photosensitive member using a polygon mirror with a polygon mirror, an attempt to reduce the spot diameter of the exposure requires a large optical system, and exposure with a small spot diameter is practically difficult. .
In addition, a method for realizing highly accurate non-contact development by jumping development has been proposed (see, for example, Patent Document 1).
Alternatively, it has been proposed to add silicone oil or fluorine oil as a lubricant in the toner (see, for example, Patent Document 2).
However, these patent documents have not proposed a high-resolution image forming method or an image forming apparatus using a small particle size toner.
JP 2006-163160 A JP 2001-166527 A

  The present invention provides an image forming method and an image forming apparatus capable of stably forming a high resolution image over a long period in an image forming apparatus using a small particle diameter toner having a particle diameter of 2 μm or more and less than 4 μm. This is a problem.

In the present invention, a toner having a volume average particle diameter of 2 μm or more and less than 4 μm and having a ratio of the volume average particle diameter to the number average particle diameter of 1 to 1.1 is outside the axial direction of the toner conveying surface of the developing roller. In addition, as a spacer that contacts the photoconductor to set a development gap, a material that swells due to moisture absorption is larger than the surface constituting member of the developing roller, and an AC superimposed voltage is applied to the photoconductor for development. Development method.
In the above developing method, the toner is partially agglomerated by adding 0.05% by mass or more and less than 2% by mass of silicone oil or fluorine oil to the toner.
Further, a toner having a volume average particle diameter of 2 μm or more and less than 4 μm and a ratio of the volume average particle diameter to the number average particle diameter of 1 to 1.1 is outside the toner conveyance surface of the developing roller in the axial direction. As a spacer that contacts the photoconductor to set a development gap, a material that swells due to moisture absorption is larger than the surface constituting member of the developing roller, and an AC superimposed voltage is applied to the photoconductor for development. The exposure to the body is a lens array in which light emitted from a plurality of light emitting elements corresponding to one lens forms an image on the photosensitive body, and the lens array has a plurality of rows extending in the main scanning direction Is used to form an image by forming an exposure spot having a diameter of 15 to 40 μm on the photoreceptor.
In the above image forming method, the toner is partially agglomerated by adding 0.05% by mass or more and less than 2% by mass of silicone oil or fluorine oil to the toner.
A developing roller that conveys toner having a volume average particle diameter of 2 μm or more and less than 4 μm and having a ratio of the volume average particle diameter to the number average particle diameter of 1 to 1.1; A developing means to which an AC superimposed voltage is applied on the outside in the direction, which is made of a member that swells due to moisture absorption more than the surface constituting member of the developing roller, and is provided with a spacer that contacts the photosensitive member to set a developing gap. The photoconductor exposure means has a lens array in which light emitted from a plurality of light emitting elements corresponding to one lens forms an image on the photoconductor, and the lens array has a plurality of rows extending in the main scanning direction. The image forming apparatus forms an exposure spot having a diameter of 15 to 40 μm on the photosensitive member.
In addition, the image forming apparatus is a toner that is partially agglomerated by adding 0.05% by mass or more and less than 2% by mass of silicone oil or fluorine oil to the toner.

As described above, a toner having a volume average particle diameter of 2 μm or more and less than 4 μm is used, and a member having a larger swelling amount than the developing roller in a high humidity environment is disposed as a spacer provided on the developing roller. A stable development gap can be formed over a wide range, and an image composed of a small spot diameter formed on the photoconductor can be developed by the applied AC superimposed voltage, thereby forming a high-resolution image. Is possible.
In particular, when silicone oil or fluorine oil is added to the toner, it causes a soft aggregation state in the toner, resulting in a toner having a large particle size before development, thus preventing scattering from the developing mechanism to the outside. The agglomerates are rapidly crushed by the AC superimposed voltage applied during development, and developed as a toner having a small particle diameter, so that a high-resolution image can be formed.
In addition, even if fluorine oil or silicone oil added to the toner adheres to a member such as a developing device, it does not fuse to the spacer or the photoreceptor due to a high release effect, and the development gap is maintained with high accuracy over a long period of time. Is done.
In addition, the added silicone oil and fluorine oil are not compatible with the resin for toner, impart negative chargeability, and improve the charging characteristics of the toner, thereby forming a high-resolution image. .

The image forming apparatus according to the present invention, in developing in the image forming apparatus, as a spacer that sets the developing gap by contacting the photosensitive member on the outer side in the axial direction of the toner conveying surface of the developing roller. Is used, and an AC superposition voltage is applied to the photoconductor, so that the volume average particle diameter is 2 μm or more and less than 4 μm, and the ratio of the volume average particle diameter to the number average particle diameter is 1 to 1. .1 enables image formation with a small-diameter toner.
The exposure to the photoconductor is a lens array in which light emitted from a plurality of light emitting elements corresponding to one lens forms an image on the photoconductor, and the lens array has a plurality of rows extending in the main scanning direction. An image forming apparatus capable of forming a high-resolution image with a toner having a small particle size by forming an exposure spot having a diameter of 15 to 40 μm on a photosensitive member and forming an image on the photosensitive member. It is.

The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention.
The image forming apparatus 1 is an apparatus in which image forming units are arranged in a tandem manner, and includes a housing 2 and a paper discharge tray 3 formed on the housing 2. The housing 2 includes a power supply unit 4, a control unit 5, An image forming unit 6, a fixing unit 7, and a paper feeding unit 8 are provided.

The image forming unit 6 is a single color image forming unit Y (for yellow), M (for magenta), C (for cyan), K (for black) that forms a plurality of (four in this embodiment) different color images. Each of the monochromatic image forming units Y, M, C, and K includes a photosensitive member 61 formed of a photosensitive member on which an organic photosensitive layer or an inorganic photosensitive layer is formed, and a developer disposed around the photosensitive member 61. Means 100 and exposure means 200 are provided.
The photosensitive members 61Y, 61M, 61C, 61K of the respective colors of the single-color image forming units Y, M, C, K are in contact with the intermediate transfer belt 62, and the primary transfer rollers 62Y, 62M are interposed via the intermediate transfer belt. , 62C, 62K are arranged. Each of these primary transfer rollers is electrically connected to a primary transfer voltage supply means (not shown). Then, by applying a primary transfer voltage to the primary transfer roller, the toner images formed on the surface of each photoreceptor 61 are sequentially transferred onto the surface of the intermediate transfer belt 62 to form a color image.

  The intermediate transfer belt 62 is driven to circulate in the direction of the arrow by the drive roller 63 and also serves as a backup roller for the secondary transfer roller 64. A rubber layer having a thickness of about 3 mm and a volume resistivity of 1000 kΩ · cm or less is formed on the peripheral surface of the drive roller 63. The rubber layer is grounded via a metal shaft and the secondary transfer roller 64 is interposed. The secondary transfer voltage conduction path is supplied. Thus, by providing the driving roller 63 with a rubber layer having high friction and shock absorption, when a recording medium such as paper or OPC film enters the contact portion between the driving roller 63 and the secondary transfer roller 64. It is difficult for the impact to be transmitted to the intermediate transfer belt 62, and deterioration of image quality can be prevented.

Further, the intermediate transfer belt 62 is provided with a cleaner portion 66 so as to face the stretching roller 65. The cleaner unit 66 includes waste toner collecting means 68 having a cleaner blade 67. The cleaner blade 67 abuts the tip of the cleaner blade 67 against the stretching roller 65 via the intermediate transfer belt 62 to remove foreign matters such as toner and paper dust remaining on the transfer belt after the secondary transfer. The foreign matter removed in this way is collected by the waste toner collecting means 68.
Further, the secondary transfer roller 64 is provided so as to be able to come into contact with the intermediate transfer belt 62 and is driven by a secondary transfer roller driving mechanism (not shown).

  The paper feed unit 8 includes a paper feed unit having a paper feed cassette 81 that stacks and holds a plurality of paper sheets and a pickup roller 82 that feeds the paper one by one from the paper feed cassette 81. The sheet is fed from the sheet feeding unit by the pickup roller 82, the sheet feeding timing is adjusted by the roller pair 83, and then fed to the secondary transfer roller 64. In the present invention, paper feed, paper, and the like each mean a recording medium capable of forming an image including not only paper but also an OPC film or the like.

The fixing unit 7 includes a heating roller 71 that includes a heating element such as a halogen heater and is rotatable, and a backup roller 72 that is disposed so as to face the heating roller 71. The toner image that has been secondarily transferred is at a predetermined temperature. Thermally fixed as an image.
The paper thus subjected to the fixing process is conveyed to a paper discharge tray 3 provided on the upper surface of the housing 2.
In the above description, an example in which the image forming units are arranged in a tandem manner has been described. However, an image forming apparatus of a type in which four color developing units are arranged around one photoconductor and sequentially developed may be used.

FIG. 2 is a diagram for explaining the image forming mechanism of the present invention, FIG. 2A is a diagram for explaining the image forming unit explained in FIG. 1 in an enlarged manner, and FIG. It is a figure explaining a process.
The image forming unit 6 includes a photoconductor 61, a developing unit 100 and a line sensor type exposure unit 200 disposed around the photoconductor 61.

  The developing unit 100 includes a developing roller 101 that conveys toner to the photosensitive member 61, a supply roller 102 that is pressed against the developing roller 101 to supply toner, and a regulation that regulates the toner that is pressed against the developing roller 101 and conveyed to the photosensitive member 61. A blade 103 and a toner collecting means 104 for collecting toner remaining on the developing roller 101 after development are provided. Further, a charging unit 105 and an exposure unit 200 are provided in the vicinity of the photoreceptor 61.

  Spacers 106 that are concentric with the developing roller 101 and have a uniform thickness are provided at both end portions of the developing roller 101 excluding the toner conveying portion 101T. The surface of the spacer 106 abuts on the photosensitive member 61, and the photosensitive member A development gap G is formed between the surface 61S and the surface 61S.

  The development gap G is adjusted to a desired size by appropriately selecting the thickness of the spacer 106. The photosensitive member 61 is set to rotate clockwise, and the developing roller 101 and the supply roller 6 are both rotated counterclockwise. The circumferential speed of the photoconductor 61 and the circumferential speed of the spacer 106 on the developing roller 101 are set to be the same or substantially the same. Thereby, non-contact jumping development of a non-magnetic one-component developer using toner which is a non-magnetic one-component developer can be realized.

3A and 3B are views for explaining the developing means of the present invention, FIG. 3A is a side view, and FIG. 3B is an enlarged cross-sectional view of one end portion of the developing roll.
The developing unit 100 includes a developing roller 101 that transports toner to the photosensitive member 61, a supply roller 102 that is pressed against the developing roller 101 and supplies toner, and a portion of the developing roller 101 other than the toner transport unit 101 </ b> T. Further, spacers 106A and 106B that are concentric with the developing roller 101 and have a uniform thickness are provided, and a predetermined developing gap G is formed by rotating the surfaces of the spacers 106A and 106B in contact with the photosensitive member 61. The

For the developing roller 101, a member having small stress shrinkage or thermal shrinkage, for example, a metal roller such as iron or a resin such as urethane is used. On the other hand, the spacers 106A and 106B provided on the developing roller 101 have elasticity and higher hygroscopicity than the developing roller 101. When the humidity increases, the spacers 106A and 106B swell and become larger in volume. It is preferable to use a substance that can increase the distance between the photosensitive member and the photosensitive member, that is, the development gap, and is less susceptible to discharge even when the humidity is high and can perform the same development.
Specifically, polyamides, polyamideimides, acetates, acrylates, rubbers, and the like having a high water absorption rate can be used, and a substance having low conductivity is preferable. Furthermore, it is preferable to join with a non-water-absorbing and insulating pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive or a silicone-based pressure-sensitive adhesive because insulation is maintained even when moisture is absorbed.

In FIG. 3A, the spacers 106A and 106B are fixed by elastic adhesive layers 107 on the surfaces of the portions other than the toner conveying portion at both ends of the developing roller 101 as shown in the sectional view in FIG. be able to. The spacer may be fixed using thermal contraction of the spacer material in addition to the adhesive layer.
The dimensional change caused by swelling of the spacers 106A and 106B is preferably such that the dimensional change in the direction perpendicular to the axis of the developing roller, that is, the thickness direction is larger than the dimensional change in the horizontal direction, that is, the axial direction and the circumferential direction.
For this purpose, as shown in FIG. 3B, the developing roller 101 has a dimensional change caused by swelling of the spacer 106A in the horizontal direction, and a dimensional change caused by swelling in the vertical direction, that is, in the thickness direction. It is preferable that the horizontal dimension fluctuation preventing unit 108 is disposed along the side surface 109 of the spacer 106 in the axial direction of the developing roller. As the horizontal dimension fluctuation preventing unit 108, a material material that is smaller in dimensional change due to moisture absorption than the spacer material can be used.
It is preferable that the horizontal dimension fluctuation preventing portion is provided in each of the spacers disposed at both ends of the developing roller.

  According to such an image forming apparatus using the developing unit 100, the spacers 106A and 106B fixed to the developing roller 101 are made of a material having higher hygroscopicity than the developing roller 101. When used in a humidity environment, the hygroscopic spacers 106A and 106B swell due to moisture absorption, and the development gap G increases. Thereby, it is possible to prevent a decrease in the discharge start voltage between the developing roller and the photosensitive member even in a high humidity environment. Accordingly, even when the image forming apparatus is used under ambient conditions of high temperature and high humidity, a relatively high development voltage can be applied, and the image quality can be improved. In particular, the application of a high development voltage is extremely effective in image formation using a toner having a small particle diameter.

  Further, by fixing the spacers 106A and 106B to the developing roller 101 with the adhesive layer 107 having elasticity, even if the spacers 106A and 106B swell in a high humidity environment, the spacer does not come off from the developing roller 101, and the developing The gap G becomes large and the effect of non-contact development can be more reliably exhibited.

  Furthermore, the dimensional change of the spacers 106A and 106B caused by swelling due to moisture absorption is set such that the dimensional change in the vertical direction, that is, the thickness direction is larger than the dimensional change in the horizontal direction, that is, the axial direction and the circumferential direction. The rate of change of the development gap G due to the swelling of 106A and 106B can be effectively increased. Further, by reducing the horizontal dimensional change that easily causes wrinkles in the spacers 106A and 106B, generation of wrinkles in the spacers 106A and 106B can be suppressed. In particular, by providing the horizontal dimensional variation preventing portion 108, it is possible to suppress the dimensional change in the axial direction of the spacers 106A and 106B due to swelling and increase the dimensional change rate in the thickness direction. As a result, the rate of change of the development gap G can be increased more effectively, and the generation of wrinkles in the spacers 106A and 106B can be more effectively suppressed.

When high-resolution image formation is performed using toner having a particle size of 2 μm or more and less than 4 μm as in the present invention, development is performed by maintaining a high-precision development gap and applying a development voltage superimposed with an alternating voltage. It is preferable to do.
The development gap is adjusted to 20 to 70 μm, and as the development voltage, it is preferable to superimpose a rectangular wave AC voltage of 800 V to 1400 V having a frequency of 4000 to 8000 Hz on a DC voltage of 100 to 400 V.
As described above, it is possible to develop a high-resolution image by using a high-precision development gap by a spacer and a toner having a size of 2 μm or more and less than 4 μm.

An example of the exposure means of the present invention will be described below with reference to the drawings.
FIG. 4 is a perspective view for explaining an example of the exposure means of the present invention. FIG. 5 is a cross-sectional view of the exposure unit shown in FIG. 4 in the sub-scanning direction.
The exposure unit 200 includes a so-called line head 201 capable of exposing the entire width at a time during image formation. A case 202 having a main scanning direction XX as a longitudinal direction is provided, and an end portion of the case 202 is provided with a positioning pin 203 and an insertion hole 204 for a fixing member such as a screw. The line head 201 is positioned with respect to the photoconductor by fitting the positioning pin 203 into a positioning hole that is formed in a photoconductor cover or the like that covers the photoconductor and is positioned with respect to the photoconductor.
Further, the line head 201 is positioned and fixed with respect to the photoreceptor by screwing and fixing a fixing screw or the like into the insertion hole 204 of the fixing member.

The case 202 holds the microlens array 205 at a position facing the surface of the photoconductor, and includes a light shielding member 206 and a substrate 207 in that order from the microlens array 205 side. A plurality of light emitting element groups G208 are provided on the surface of the substrate 207 opposite to the side facing the microlens array 205. That is, the plurality of light emitting element groups G208 are arranged on the back surface of the substrate 207 at a predetermined interval from each other in the main scanning direction XX and the sub scanning direction YY.
Moreover, as each light emitting element group G208, an organic EL light emitting element, a light emitting diode, or the like that emits light capable of exposing the photoreceptor surface 61S with a small spot diameter can be used.

  As shown in the drawing, when the light emitting elements are arranged on the back surface of the substrate 207, the light beams emitted from the plurality of light emitting element groups G208 are transmitted through the substrate 207 toward the light shielding member 206 side. In the light shielding member 206, a plurality of light guide holes 209 are formed one-on-one with respect to the plurality of light emitting element groups G208. The light guide hole 209 is formed as a substantially cylindrical hole that penetrates the light shielding member 206 with a line parallel to the normal line of the substrate 207 as a central axis. Therefore, all the light emitted from the light emitting elements belonging to one light emitting element group G208 passes through the same light guide hole 209 toward the microlens array 205, and interference between light beams emitted from different light emitting element groups G208 occurs. This is prevented by the light shielding member 206.

Then, the light beam that has passed through the light guide hole 209 formed in the light shielding member 206 is imaged as a spot on the surface of the photoreceptor by the microlens array 205.
In the exposure means, the back cover 211 is pressed against the case 202 by the fixing device 210 via the substrate 207, and the fixing device 210 has an elastic force that presses the back cover 211 toward the case 202, and is applied thereto. By pressing the back cover with elastic force, the case 202 is sealed so that light leaks from the inside of the case 202 and light does not enter from the outside of the case 202. In addition, a plurality of fixing devices 210 are provided in the longitudinal direction of the case 202. The light emitting element group G208 is covered with a sealing member 212.

FIG. 6 is a diagram illustrating a light emitting element group including a plurality of light emitting elements.
Two light emitting element units U208 arranged by arranging four light emitting elements 208 at a predetermined interval in the main scanning direction XX are arranged in the sub scanning direction YY to constitute one light emitting element group G208. That is, a light emitting element group G208 composed of eight light emitting elements is configured corresponding to each microlens 213 indicated by a circle in FIG.
The light emitting element group G208 includes three light emitting element group rows L208 arranged in the main scanning direction XX and a predetermined number of light emitting element groups L208 arranged in the sub scanning direction YY according to the size of the image to be formed. They are arranged two-dimensionally. All the light emitting element groups G208 are arranged at different positions in the main scanning direction. Further, a plurality of light emitting element groups G208 are arranged so that the light emitting element unit U208A1 and the light emitting element unit U208B1 of the light emitting element group G208 adjacent in the main scanning direction position are different from each other in the sub scanning direction.

  Further, when the geometric gravity center point of the light emitting element unit U208 is the position of the light emitting element, the distance between the two light emitting elements means the distance between the geometric gravity centers of the respective light emitting elements. Therefore, the light emitting element group geometric centroid means the geometric centroid of all light emitting element positions belonging to the same light emitting element group G208. In addition, the main scanning direction position and the sub scanning direction position mean the main scanning direction component and the sub scanning direction component at the position of interest, respectively.

Corresponding to the arrangement of the light emitting elements G208, a light guide hole is formed in the light shielding member 206, and a microlens array 205 including a plurality of microlenses 213 is arranged. The barycentric position of the light emitting element group G208, the central axis of the light guide hole, and the optical axis of the lens pair constituted by the microlenses 213A and 213B are configured to substantially coincide with each other. Then, the light beam emitted from the light emitting element 208 of the light emitting element group G208 enters the microlens array 205 through the corresponding light guide hole, and is imaged as a spot on the surface of the photoreceptor by the microlens array 205. .
As described above, high-resolution exposure with a spot diameter of 15 to 40 μm can be realized by using the line head-shaped exposure means in which individual light emitting elements are arranged close to each other.
In the present invention, the exposure spot diameter means the diameter of the light amount that is 1 / e ² with respect to the peak light amount (where e is the base of the natural logarithm).

Hereinafter, the toner used for image formation in the image forming method and the image forming apparatus of the present invention will be described.
The toner used in the present invention is a dispersion of resin oil droplets, wax dispersoids, colorant dispersoids, etc. produced by phase inversion emulsification of a colored resin solution containing a binder resin, a colorant, a wax, and an organic solvent. The particle size produced by the method of growing toner particles of a predetermined particle size by changing the emulsified state by adding an aqueous electrolyte solution and changing the shearing force applied to the fine particles by changing the stirring speed is small. Toner is preferred.

The dispersoid in the emulsion suspension formed by phase inversion emulsification of the colored resin solution exists stably in the aqueous medium by forming an electric double layer around it. A stable dispersion state is destroyed by the electrolyte. In this state, when the fine particles collide with each other, coalescence proceeds and particles having a large particle diameter are formed.
When the shearing force is large, fine particles remain, or particles that are coalesced by collision between particles are separated and dispersed again by the shearing force, so that coalescence does not proceed in practice.
Therefore, in the coalescence step, after addition of the aqueous electrolyte solution, after stirring at high speed so that the aqueous electrolyte solution is uniformly dispersed in the emulsified suspension, the coalescence is less than the rate-limiting rate at which coalescence proceeds smoothly. It is possible to grow to a predetermined particle size by lowering the stirring speed to the unitary stirring speed that is

  The coalescence depends on the amount of the aqueous electrolyte solution added together with the stirring speed, and is affected by the degree of destruction of the dispersed state by the added aqueous electrolyte solution. Accordingly, when the dispersion state does not change due to the added electrolyte aqueous solution, the particle size formed by coalescence reaches saturation even if stirring is continued at the coalescence stirring speed. For these reasons, the amount of aqueous electrolyte solution added in the coalescence step and the stirring time at the coalescence stirring speed are determined by measuring the particle size formed by coalescence.

Hereinafter, the production process of the toner of the present invention will be described.
1st process: Colored resin solution preparation process It is the process of manufacturing a colored resin solution by melt | dissolving or disperse | distributing the binder resin which has resin, such as a polyester resin, a colorant, and wax in an organic solvent.
Second step: Phase inversion emulsification step After adding the basic compound, water is added to the colored resin solution to perform phase inversion emulsification to obtain an emulsified suspension.
Third step: coalescence step An aqueous electrolyte solution is added to the prepared emulsification suspension to coalesce fine particles such as resin oil droplets, wax dispersoid, and colorant dispersoid in the emulsion suspension. This is a step of generating particles.
Fourth Step: Separation and Drying Step In this step, after removing the organic solvent under reduced pressure, the coalesced particles are separated from the aqueous medium, washed and dried to form toner base particles.

  First, the colored resin solution preparation step, which is the first step, will be described. In the colored resin solution preparation step, first, a binder resin mainly composed of a self-dispersing synthetic resin dispersed in an aqueous medium such as a polyester resin in an organic solvent, a coloring agent, and a wax are introduced, dissolved or dissolved. Disperse and finely disperse or dissolve below the toner particle size.

  The binder resin and the colorant are preferably dissolved or dispersed in an organic solvent with a high-speed stirrer. In this case, the colorant may be pre-dispersed in advance to prepare a master kneading chip and finely dispersed below the toner particle diameter to be produced. Additives such as wax may be mixed after the master kneading chip is prepared in advance. Alternatively, a master solution finely dispersed below the toner particle diameter by wet dispersion using media may be used.

In the colored resin solution preparation step, Desper (manufactured by Asada Iron Works), T.W. K. A high-speed stirrer such as a homomixer (Primix) can be used. The blade tip speed at this time is preferably 4 to 30 m / s, and more preferably 8 to 25 m / s. By using the high-speed stirrer, the binder resin can be efficiently dissolved in the organic solvent, and uniform fine dispersion of the colorant in the binder resin solution can be achieved. That is, the coloring agent finely dispersed in advance can be held in the colored resin solution by stirring at high speed.
When the blade tip speed is lower than 4 m / s, the fine dispersion of the colorant in the colored resin solution is insufficient, which is not preferable. On the other hand, when it is higher than 30 m / s, heat generation due to shearing is increased, and it is not preferable because uniform stirring becomes difficult in combination with volatilization of the solvent. Moreover, the temperature in the case of melt | dissolving or disperse | distributing has the preferable range of 20-60 degreeC, and the range of 30-50 degreeC is more preferable.

  As an organic solvent, the thing whose solubility with respect to water in 25 degreeC is 0.1-30 mass% is preferable, and what is 0.1-25 mass% is more preferable. The boiling point at normal pressure is preferably lower than the boiling point of water. Examples of such an organic solvent include ketones such as methyl ethyl ketone and methyl isopropyl ketone, and esters such as ethyl acetate and isopropyl acetate. These organic solvents can be used in combination of two or more, but from the viewpoint of solvent recovery, it is preferable to use the same type of solvent alone. In addition, the organic solvent is preferably one having a low boiling point because it dissolves or disperses the polyester resin and is easy to remove the solvent in a later step. Here, as the organic solvent for dissolving the polyester resin, it is preferable to use methyl ethyl ketone and ethyl acetate, which are excellent in solubility and dispersibility. In particular, it is more preferable to use methyl ethyl ketone.

Moreover, it is preferable to add an emulsifier in the preparation process of the colored resin solution.
In order for the emulsifier to function in the coalescing step, it is necessary to have a characteristic capable of maintaining dispersion stability even in the presence of an electrolyte added later. Examples of emulsifiers having such properties include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene Nonionic emulsifiers such as oxyethylene sorbitan fatty acid esters or various pluronics, alkyl sulfate ester type, alkyl sulfonate type anionic emulsifiers, and quaternary ammonium salt type cationic emulsifiers is there. Moreover, an alkylbenzene sulfonate type emulsifier and a linear alkyl benzene sulfonic acid type emulsifier can be mentioned.
The above-mentioned emulsifiers may be used alone or in combination of two or more. That is, in the production method of the present invention, it is possible to prevent non-uniform coalescence by adding an electrolyte in the presence of an emulsifier. Thereby, a preferable particle size distribution is obtained and an improvement in yield is achieved.

  Moreover, 0.1-3.0 mass% is preferable with respect to solid content, and, as for the quantity of the emulsifier to use, it is more preferable that it is 0.3-2.0 mass%, and 0.3-1. It is especially preferable that it is 5 mass%. This is because if it is less than 0.1% by mass, the desired effect of preventing the generation of coarse particles cannot be obtained. On the other hand, when the amount is more than 3.0% by mass, coalescence does not proceed sufficiently even if the amount of the electrolyte is increased, and particles having a predetermined particle diameter cannot be obtained. As a result, fine particles remain and yield. This is because of lowering.

  Next, in the phase inversion emulsification step of the second step, after adding the basic compound, the colored resin-containing composition is suspended or emulsified by adding water to obtain an emulsified suspension. Here, it is preferable to gradually add water to the colored resin solution in which the carboxyl group of the polyester resin is neutralized with a basic compound. By neutralizing the carboxyl group, the hydrophilicity of the functional group portion is improved and the affinity with water is improved.

  The dropped water is hydrated to the functional group portion and dissolved or finely dispersed together with the stirring effect. On the other hand, the binder resin has strong acid-base interaction through an aqueous medium, and the viscosity increases with the addition of water. When a certain amount of water is added, there is a point that the viscosity decreases, which is called a so-called phase inversion point. Until just before this, the viscosity increases and reaches a maximum value. The increase in viscosity correlates with the addition amount of the basic compound, and the increase in viscosity increases as the addition amount increases.

  On the other hand, in the present invention, the amount of the basic compound affects not only the phase inversion emulsification step of the second step but also the uniformity and speed at the time of coalescence particle generation in the coalescence step of the third step described later. The basic compound is preferably in the range of 1 to 3 equivalents relative to the carboxyl group of the polyester resin. Moreover, the range of 1-2 equivalent is still more preferable. Thus, by adding in excess of the amount required to neutralize all of the carboxyl groups of the polyester resin, it is possible to prevent the formation of irregularly shaped particles in the coalescence process, and the particle size distribution can be reduced. It can be a narrow range.

  However, if the total amount of the basic compound is added before emulsification, the viscosity increases during emulsification, and non-emulsified foreign matter is generated due to uneven stirring, which is mixed in the finally obtained toner and adversely affects the development characteristics. Will be affected. Therefore, the amount of the basic compound is preferably 0.6 to 1.2 equivalents. When the amount is less than 0.6 equivalent, the dispersion of the colorant or the additive such as wax becomes non-uniform during emulsification or an unemulsified product is generated. On the other hand, when the amount is more than 1.2 equivalents, an effect due to an increase in viscosity is observed, which is not preferable.

The ratio of the organic solvent / organic solvent + water after completion of the phase inversion emulsification step is preferably in the range of 20 to 35% by mass, and more preferably in the range of 23 to 30% by mass. As described above, the amount of water up to the phase inversion point decreases as the amount of organic solvent in the colored resin solution preparation step decreases, and increases as the amount of basic compound increases.
At the phase inversion point, the viscosity of the emulsified suspension may be high, and the colored resin solution may not be completely finely dispersed in the aqueous medium. Therefore, it is preferable to add more water. The amount of water added is preferably in the range of 50 to 80% by weight of the total water used up to the phase inversion point.

The polyester resin used in the present invention preferably has an acid value of 3 to 30 KOHmg / g, more preferably 5 to 20 KOHmg / g.
This is not preferred if the acid value of the polyester resin is less than 3, since the production of an emulsified suspension in which the polyester resin and the organic solvent are emulsified in water is not carried out smoothly and coarse particles are generated.
On the other hand, if the acid value of the polyester resin is greater than 30, the charge amount in the toner use environment is not stable, which is not preferable. The polyester resin having an acid value of 3 to 30 KOHmg / g becomes an anionic type by neutralizing the carboxyl group with a basic compound. As a result, the hydrophilicity of the resin increases and can be stably dispersed or dissolved.

  Examples of the basic compound for neutralization include inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia, and organic bases such as diethylamine, triethylamine, and isopropylamine. In particular, an aqueous solution of an inorganic base such as ammonia, sodium hydroxide, or potassium hydroxide is preferred.

  In the emulsified suspension produced by the above method, the colored resin solution exists in the state of being emulsified in an aqueous medium as resin oil droplets, colorant dispersoids, wax and the like. The state varies depending on the type and amount of organic solvent used, the acid value of the polyester resin, the amount of basic compound used, the stirring conditions, and the like, but it is preferably emulsified as fine oil droplets of 1 μm or less. Such a state is preferable because the stability of the emulsified suspension, the stability of coalescence in the subsequent steps, the particle size distribution of the coalesced particles, and the like are improved.

Next, the unification process which is the 3rd process is explained. By adding an electrolyte in the presence of an emulsifier, coalesced particles that are a unitary of fine particles can be produced.
The coalescing step includes a step of depositing fine particles of the colored resin solution by dropping the electrolyte aqueous solution in the presence of an emulsifier and a coalescing step in which the associated particles grow thereafter.
First, fine particles formed from individual dispersoids of resin oil droplets, colorant dispersoids, or wax dispersoids, and fine particles in which these dispersoids are composited are precipitated, and the size ranges from 0.01 μm to 0 The size is about 4 μm.
Next, coalesced particles are obtained by coalescing the fine particles.
In the coalescence process, by adding an aqueous electrolyte solution to the emulsified suspension, fine oil droplets of the emulsified colored resin solution are salted out or destabilized, and a plurality of fine particles are integrated to form a coalesced mixture. Progresses and the desired particle size can be obtained.

  In addition, the addition of the electrolyte aqueous solution not only brings together the fine particles containing the colorant, but also causes the polyester resin dissolved in the aqueous medium to salt out or destabilize to precipitate the fine particles of the polyester resin. The coalesced particles can be obtained by adhering to the surface of the fine particles containing the agent or the coalesced particles already coalesced.

Examples of the electrolyte used here include sodium sulfate, ammonium sulfate, potassium sulfate, sodium hydrogen sulfate, ammonium hydrogen sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, sodium chloride, potassium chloride, ammonium chloride, calcium chloride. Water-soluble salts such as sodium hydrogen carbonate, ammonium hydrogen carbonate, and sodium acetate can be used as the electrolyte. These electrolytes may be used alone or as a mixture of two or more kinds of substances. Of these, monovalent cation sulfates and carbonates such as sodium sulfate and ammonium sulfate are preferred for promoting uniform coalescence.
In addition, the resulting coalesced particles are swollen by the solvent, and the hydration state of the particles is unstable due to the addition of an electrolyte. Therefore, the particles are collided with each other by stirring with low shear force. It is preferable to proceed one.

In order to promote uniform coalescence, agitation conditions for coalescence are important. For example, an anchor wing, a turbine wing, a Faudler wing, a full zone wing, a Max blend wing (registered trademark), and a meniscus wing are used. Among them, it is preferable to use a large blade having excellent uniform mixing characteristics even at a low rotation, such as Max Blend blade (registered trademark) or full zone blade. The peripheral speed of the stirring blade for generating a uniform unity is preferably 0.2 to 10 m / s, and more preferably stirring with a low shear of less than 0.2 to 8 m / s. In particular, 0.2 to 6 m / s is preferable. If the peripheral speed of the stirring blade is faster than 10 m / s, it is not preferable because fine particles remain. On the other hand, if the peripheral speed is slower than 0.2 m / s, stirring is not uniform and coarse particles tend to be generated, which is not preferable. Under the above-described conditions, coalescence proceeds only by collision of fine particles, and the coalescence does not dissociate and disperse again. In particular, since coalescence proceeds preferentially from fine particles in the coalescence process, generation of ultrafine particles is small, and a narrow particle size distribution is achieved, so that an improvement in yield can be achieved.
That is, in the colored resin solution preparation step and the phase inversion emulsification step, it is preferable to stir with a high speed stirrer such as Desper (manufactured by Asada Iron Works), and in the coalescing step, a large blade capable of uniform mixing at low speed is suitable. It is preferable to carry out the coalescing step by transferring the emulsified suspension obtained in the phase inversion emulsification step to another container attached to the large blade.

Moreover, 0.5-15 mass% is preferable with respect to solid content, and, as for the quantity of the electrolyte to be used, it is more preferable that it is 1-12 mass%, and it is especially preferable that it is 1-6 mass%. When the amount of the electrolyte is less than 0.5% by mass, coalescence does not proceed sufficiently.
On the other hand, when the amount of the electrolyte is more than 15% by mass, the coalescence becomes non-uniform, and aggregates and coarse particles are generated, resulting in a decrease in yield.
Moreover, it is not preferable that the electrolyte concentration is high because aggregates are likely to be generated at the time of precipitation of the dissolved polyester resin due to salting out in the initial coalescence. On the other hand, when the electrolyte concentration is low, a large amount of electrolyte is required for salting out and coalescence, and fine particles are likely to remain, which is not preferable.

That is, at the time of precipitation at the beginning of coalescence, since the size is small and the specific surface area is large, it is easily affected by the concentration unevenness in the vicinity of the added electrolyte aqueous solution, and aggregation may occur due to the concentration unevenness. For this reason, it is preferable that the concentration is set to be low so that the concentration unevenness of the electrolyte does not occur at the initial stage of fine particles.
In addition, when the particle size is grown to exceed 3 μm, it is preferable to control the particle growth rate by increasing the electrolyte concentration and adjusting the amount of the electrolyte aqueous solution added accordingly. When a large amount of low-concentration electrolyte aqueous solution is added, the amount of the added solution increases, the organic solvent ratio decreases, and coalescence does not progress and fine particles remain easily.

  In the present invention, a colored resin solution containing a binder resin, a colorant, a wax, and an organic solvent is formed by phase-inversion emulsification to form an emulsion suspension, and particles of a predetermined size are grown from the emulsion suspension. It is. Particle growth can be accomplished by adding electrolyte to the emulsified suspension and stirring.

When a toner having a volume average particle size of 4 μm or less is produced, the electrolyte concentration is preferably in the range of 2 to 4% by mass at the stage where the particle size of the fine particles in the initial coalescence grows to 3 μm. Further, when the particle size is further increased beyond 3 μm, a concentration in the range of more than 4 mass% and 6 mass% is preferable.
In particular, at the final stage of coalescence, it is preferable to set the particle growth rate after dropping of the aqueous electrolyte solution in the range of 0.1 to 0.5 μm / 10 min on the basis of the volume average particle diameter.

When adding the aqueous electrolyte solution in the coalescence step, it is preferable to increase the stirring speed in order to mix the electrolyte uniformly and quickly into the system. It is preferable because generation of aggregates due to dropping of the aqueous electrolyte solution can be suppressed. Moreover, 10-50 degreeC is preferable, as for the temporary temperature, it is more preferable that it is 20-40 degreeC, and it is especially preferable that it is 20-35 degreeC.
This is because coalescence is difficult to proceed when the temperature is lower than 10 ° C. Moreover, when temperature is higher than 50 degreeC, it is because a coalescence rate will become quick and it will become easy to generate | occur | produce an aggregate and a coarse particle. In the production method of the present invention, for example, coalescence particles can be produced by coalescence under a low temperature condition of 20 to 40 ° C.

  In the coalescence, the colored resin fine particles swollen by the organic solvent are stirred at a predetermined rotation speed so that the colored resin fine particles collide with each other and are fused to grow particles. Therefore, when the coalescence process proceeds by dividing the coalescence process into a plurality of processes, a high shear force is applied between the next coalescence process and stirring at a speed higher than the agitation speed at which coalescence proceeds. By providing the aging period to give, the coalesced colored resin fine particles can be aged to increase the circularity of the coalesced particles.

  In addition, the particle growth can be expressed by creating a particle growth curve plotted from the time and the particle size in order to maintain a substantially constant growth rate under a certain condition. As a result, the arrival time of the target particle diameter can be estimated from the curve. The coalescence is preferably stopped by adding water.

In addition, the coalesced particles obtained in the coalescing step are swelled by encapsulating an organic solvent in an aqueous medium, and therefore easily aggregate when placed at a high temperature condition or left standing.
Therefore, it is preferable to carry out the desolvation under reduced pressure in order to carry out the desolvation quickly under a low temperature condition. In removing the solvent, an antifoaming agent is preferably added. The antifoaming agent is preferably in the form of a silicone emulsion. Examples of the silicone-based antifoaming agent include BY22-517, SH5503, SM5572F, BY28-503 (manufactured by Toray Dowco Ichining Silicone), KM75, KM89, KM98, KS604, KS538 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like. is there. Especially, BY22-517 is preferable as a thing with little influence on a physical property and a high defoaming effect. The amount of the antifoaming agent is preferably 30 to 100 ppm with respect to the solid content.

  The toner particles produced by the production method of the present invention are characterized in that a colorant, wax, or the like is included in a binder resin, and the colorant, wax, etc. are observed by observation with a transmission electron microscope or the like. It can be confirmed that the particles are contained in the particles and are almost uniformly dispersed.

In addition, the shape of the coalesced particles obtained in the coalescing step is determined by a flow type particle image analyzer (FPIA-2000 manufactured by Sysmex), and the circularity is around the circle corresponding to the projected area of the observed particle image. The average value of the numerical value represented by the ratio of the length of the image and the perimeter of the observed projected image of the particle is the average circularity.
The toner particles obtained by the method of the present invention have a substantially spherical or spherical shape with an average circularity of 0.95 or more to 0.97 or more, and powder flowability and transfer efficiency are improved.

  In the coalescence process, the coalesced particles grown to the target particle diameter include the coalesced particles after adding water to the aqueous medium containing the coalesced particles and stopping coalescence in the separation and drying process. The organic solvent used can be removed from the aqueous medium and dried.

  In the separation and drying step, the colored resin particles are separated, washed and dehydrated to obtain a colored resin fine particle cake. Separation and dehydration from the aqueous medium can be performed by a centrifugal separator, or a separation means such as a filter press or a belt filter. The washing can be performed by stirring and dispersing the obtained colored resin fine particle cake again in water and further dehydrating. Next, toner base particles can be obtained by drying the particles. Further, when a dispersion stabilizer is added in the previous step, it is preferable to wash more sufficiently.

  Drying is fluidized bed type drying such as ribocorn type dryer (Okawara Seisakusho), mixing vacuum dryer such as Nauta mixer (Hosokawa Micron), fluidized bed dryer (Okawara Seisakusho), vibration fluidized bed dryer (Central Chemical). Dried in the machine.

  As for the particle size distribution of the toner, a 50% volume particle size / 50% number particle size of 1.1 or less can be obtained by measurement with a flow type particle image analyzer (FPIA-2000 manufactured by Sysmex).

The polyester resin used in the present invention will be described. The polyester resin is preferably a mixture of a cross-linked polyester resin and a linear polyester resin, and can be obtained by reacting a compound selected from the following raw materials.
The cross-linked polyester is preferably produced by reacting a dibasic acid or a derivative thereof, a divalent alcohol, and a polyvalent compound as a cross-linking agent. In particular, it is preferable to produce by reacting a dibasic acid or a derivative thereof, a divalent aliphatic polyhydric alcohol, and a polyvalent epoxy compound as a crosslinking agent.
The linear polyester resin is produced by reacting a dibasic acid with a divalent alcohol. In particular, it is preferable to produce by reacting a dibasic acid with a divalent aliphatic alcohol.

  Acid components used in the production of cross-linked polyester resins and linear polyester resins include phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, adipic acid, maleic acid, maleic anhydride, fumaric acid, itacone Examples thereof include dicarboxylic acids such as acid, citraconic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, azelaic acid, sebacic acid, and derivatives or esterified products thereof.

  Examples of the divalent aliphatic alcohol component include 1,4-cyclohexanedimethanol, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, butanediol, and pentanediol. Hexanediol, polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide random copolymer diol, ethylene oxide-propylene oxide block copolymer diol, ethylene oxide-tetrahydrofuran copolymer diol, polycaprocactone diol, etc. Diols are mentioned.

Use of an aliphatic alcohol in the cross-linked polyester resin and the linear polyester resin is preferable because compatibility with waxes is improved and offset resistance is improved. Moreover, fixing property at low temperature is improved by softening the polyester main chain.
When producing a crosslinked polyester resin, a polyvalent epoxy compound is further used as a crosslinking agent.
Examples of the polyvalent epoxy compound include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, ethylene glycol diglycidyl ether, hydroquinone diglycidyl ether, N, N-diglycidyl aniline, glycerin triglycidyl ether. , Trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetrakis 1,1,2,2 (p-hydroxyphenyl) ethane tetraglycidyl ether, cresol novolac type epoxy resin, phenol novolac type epoxy Resin, polymer of vinyl compound having epoxy group, or copolymer, epoxidized resorcinol-acetone condensate, partial Epoxidized polybutadiene, polymers of vinyl compounds having an epoxy group, or a copolymer, such as semi-drying or drying fatty acid ester epoxy compound. Among the above compounds, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, trimethylol ethane Triglycidyl ether and pentaerythritol tetraglycidyl ether are more preferably used.

  Specifically, as examples of bisphenol A type epoxy resin, Epicron 850, Epicron 1050, Epicron 2055, Epicron 3050, etc. manufactured by Dainippon Ink & Chemicals, Inc., Epicron 830 manufactured by Dainippon Ink and Chemicals, Ltd. as examples of bisphenol F type epoxy resins, Epicron 520 and the like are examples of orthocresol novolak type epoxy resins, Epicron N-660, N-665, N-667, N-670, N-673, N-680, N-690, manufactured by Dainippon Ink and Chemicals, Inc. Examples of phenol novolac type epoxy resins such as N-695 include Epicron N-740, N-770, N-775, N-865 and the like manufactured by Dainippon Ink and Chemicals, Inc. Examples of the polymer or copolymer of a vinyl compound having an epoxy group include a homopolymer of glycidyl (meth) acrylate, an acrylic copolymer, and a copolymer with styrene.

  Moreover, the epoxy compound mentioned above can also be used in combination of 2 or more types, Furthermore, the mono epoxy compound described below can also be used together as a modifier | denaturant of resin. Examples of the monoepoxy compound that can be used at the same time include phenyl glycidyl ether, alkylphenyl glycidyl ether, alkyl glycidyl ether, alkyl glycidyl ester, glycidyl ether of alkylphenol alkylene oxide adduct, α-olefin oxide, monoepoxy fatty acid alkyl ester, and the like. Is mentioned.

By using these monoepoxy compounds in combination, fixability and resistance to offset at high temperatures are improved. Among these, alkyl glycidyl esters are particularly preferably used.
A specific example is neodecanoic acid glycidyl ester (Shell Japan Cardura E).

  The cross-linked polyester resin and the linear polyester resin can be obtained, for example, by performing a dehydration condensation reaction or a transesterification reaction in the presence of a catalyst using the raw material components described above. The reaction temperature and reaction time in this case can be 2 to 24 hours at 150 to 300 ° C.

  As a catalyst for performing the above reaction, for example, tetrabutyl titanate, zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, paratoluenesulfonic acid and the like can be used.

  The use ratio of the cross-linked polyester resin and the linear polyester resin used in the present invention is (mass of cross-linked polyester resin) / (mass of linear polyester resin) = 5 / 95-60 / 40. Can do. Moreover, it is good also as 10 / 90-40 / 60 or 20 / 80-40 / 60. By adjusting the ratio of the cross-linked polyester resin, high temperature offset resistance, melt viscosity (T1 / 2 temperature), low temperature fixability and the like can be adjusted.

The glass transition temperature (Tg) of the cross-linked polyester resin is preferably 40 to 85 ° C, and particularly preferably 40 to 75 ° C. When the glass transition temperature (Tg) is lower than 40 ° C., a blocking phenomenon (thermal aggregation) tends to occur when the toner is stored, transported, or exposed to a high temperature inside the image forming apparatus. Further, if the glass transition temperature (Tg) is higher than 85 ° C., the low-temperature fixability is lowered, which is not preferable.
The glass transition temperature (Tg) of the linear polyester resin is preferably 35 to 70 ° C, and particularly preferably 35 to 65 ° C. When the glass transition temperature (Tg) is lower than 35 ° C., a blocking phenomenon, that is, thermal aggregation tends to occur when the toner is stored, transported, or exposed to a high temperature inside the image forming apparatus. On the other hand, if the glass transition temperature (Tg) is higher than 70 ° C., the low-temperature fixability is lowered, which is not preferable.

  In addition, the softening point of the cross-linked polyester resin is preferably 150 ° C. or higher, and particularly preferably 150 ° C. to 220 ° C. Here, the softening point of the cross-linked polyester resin is more preferably 150 ° C. to 200 ° C., and particularly preferably 150 ° C. to 190 ° C. When the softening point is less than 150 ° C., the toner tends to cause an aggregation phenomenon, which may hinder image formation. On the other hand, if it exceeds 220 ° C., the fixability tends to deteriorate. Moreover, it is preferable that the softening point of a linear polyester resin is 85 degreeC or more, and it is preferable that it is 85 to 130 degreeC especially. Here, the softening point of the linear polyester resin is more preferably 85 ° C to 120 ° C, and particularly preferably 85 ° C to 110 ° C. Similar to the cross-linked polyester resin, when the softening point is less than 85 ° C., the glass transition temperature is lowered, and the toner tends to cause an aggregation phenomenon, and when it exceeds 130 ° C., the fixability is likely to deteriorate. .

  Moreover, it is preferable that the softening point of the mixture of cross-linked polyester resin and linear polyester resin is 100 ° C to 150 ° C. More preferably, the temperature is 120 to 140 ° C. When the softening point is less than 100 ° C., the toner tends to cause an aggregation phenomenon, and when it exceeds 150 ° C., the fixability tends to deteriorate.

The softening point of the polyester resin in the present invention is a T1 / 2 temperature measured using a constant load extrusion capillary type rheometer (Shimadzu Corporation flow tester CFT-500). The measurement conditions were a piston cross-sectional area of 1 cm ² , a cylinder pressure of 0.98 MPa, a die length of 1 mm, a die hole diameter of 1 mm, a measurement start temperature of 50 ° C., a temperature increase rate of 6 ° C./min, and a sample mass of 1.5 g. .
In addition, the glass transition point (Tg) was measured by using a differential scanning calorimeter (DSC-60A, manufactured by Shimadzu Corporation), putting a 20 mg sample in an aluminum crimp container, and heating at 180 ° C. at a temperature rising rate of 10 ° C./min. The temperature was cooled to 25 ° C. from 180 ° C. at a rate of temperature decrease of 10 ° C./min, and again raised to 180 ° C. at a rate of temperature increase of 10 ° C./min. The displacing temperature was taken as the glass transition point.

In the production method of the present invention, waxes that can be introduced in the colored resin solution preparation step include hydrocarbon waxes such as polypropylene wax, polyethylene wax, and Fischer-Tropsch wax, synthetic ester waxes, carnauba wax, and rice. Mention may be made of waxes selected from natural ester waxes such as waxes. Of these, natural ester waxes such as carnauba wax and rice wax, synthetic ester waxes obtained from polyhydric alcohols and long-chain monocarboxylic acids, and hydrocarbon waxes such as Fiescher-Tropsch wax are suitable. Examples of the synthetic ester wax include WEP-5 and WEP-7 (manufactured by NOF Corporation).
In the method of the present invention, a sufficient amount of wax required for the toner can be contained, but 1 to 40% by mass is preferably contained in the toner particles.

The colored resin solution can be prepared by mixing a charge control agent. As the positively chargeable charge control agent, a nigrosine compound, a quaternary ammonium compound, an onium compound, a triphenylmethane compound, or the like can be used. In addition, basic group-containing compounds such as amino groups, imino groups, and N-heterocycles such as tertiary amino group-containing styrene acrylic resins can be used in combination with the nigrosine compound as a positively chargeable charge control agent. Further, a small amount of a negative charge control agent such as an azo dye metal complex or a salicylic acid derivative metal complex salt can be used in combination. Negative charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes Examples thereof include dyes, calixarene type phenol condensates, cyclic polysaccharides, resins containing carboxyl groups and / or sulfonyl groups.
The content of the charge control agent is preferably 0.01 to 10% by mass in the toner particles. It is especially preferable that it is 0.1-6 mass%.

  Examples of colorants that can be added in the colored resin solution preparation step include carbon black, C.I. I. Pigment Black 11 and other iron oxide pigments, C.I. I. Examples thereof include iron-titanium complex oxide pigments such as Pigment Black 12, or carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black.

  As the blue colorant, phthalocyanine C.I. I. Pigment Blue 1, 2, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 15, 16, 17: 1, 27, 28, 29, 56, 60, 63, and the like. Among these, C.I. I. Pigment Blue 15: 3, 15, 16, 60 is preferable. I. Pigment Blue 15: 3, 60 is more preferable.

Examples of yellow colorants include C.I. I. Pigment Yellow 1, 3, 4, 5, 6, 12, 13, 14, 15, 16, 17, 18, 24, 55, 65, 73, 74, 81, 83, 87, 93, 9.4, 95, 97 , 98, 100, 101, 104
, 108, 109, 110, 113, 116, 117, 120, 123, 128, 129, 133, 138, 139, 147, 151, 153, 154, 155, 156, 168
, 169, 170, 171, 172, 173, 180, 185 and the like. Among these, C.I. I. Pigment Yellow 17, 74, 93, 97, 110, 15.5 and 180 are preferred. I. Pigment Yellow 74, 93, 97, 180 is more preferable. I. Pigment Yellow 93, 97, and 180 are more preferable.

  Examples of red colorants include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 17, 18, 22, 23, 31, 37, 38, 41, 42, 48: 1, 48 : 2, 48: 3, 48: 4, 49: 1, 49: 2, 50: 1, 52: 1, 52: 2, 53: 1, 54, 57: 1, 58: 4, 60: 1, 63 : 1, 63: 2, 64: 1, 65, 66, 67, 68, 81, 83, 88, 90, 90: 1, 112311, 4, 115, 122, 123, 133, 144, 146, 147, 149 , 150, 151, 166, 168, 170, 171, 172, 174, 175, 176, 177, 178, 179, 184, 185, 187, 188, 189, 190, 193, 194, 202, 208, 209, 214 , 216, 220, 221 24,242,243,243: 1,245,246,247, and the like. Among these, C.I. I. PigmentRed 48: 1, 48: 2, 48: 3, 48: 4, 53: 1, 57: 1, 122, 184 and 209 are preferred. I. Pigment Red 57: 1, 122, 184 and 209 are more preferable.

  The content of the colorant is preferably 1 to 20% by mass in the toner particles, more preferably 2 to 18% by mass, and still more preferably 2 to 15% by mass. These colorants can be used alone or in combination of two or more.

  The toner particles produced by the method of the present invention can be adjusted in fluidity, chargeability, etc. by adding fine particles such as silica and titania, or those subjected to hydrophobizing treatment as external additives. .

In addition, a toner having a small particle diameter can form an image with excellent resolution by using an image forming apparatus combining the developing means and the exposure means of the present invention. It is possible to form an image and form an image as toner having a large particle diameter in a pseudo manner.
The soft aggregation of the toner can be realized by adding an oily liquid such as fluorine oil or silicone oil to the small particle size toner. Further, fluorine oil and silicone oil are preferable because they also function as a lubricating oil. Specific examples include dimethyl silicone oil (KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd.) or perfluoropolyether (BARRITERTA J 25 V manufactured by NOK).

Further, it is preferable to add 0.05 to 2 parts by mass of fluorine oil or silicone oil to 100 parts by mass of the toner. When the addition amount is less than 0.05 parts by mass, a sufficient effect cannot be obtained. When the addition amount is more than 2 parts by mass, even if a development voltage on which an alternating voltage is superimposed is applied during development, it is difficult to obtain a sufficient effect. This is not preferable because it is difficult to disintegrate the aggregate.
Toner that has become soft agglomerated by the addition of a predetermined amount of fluorine oil or the like, when a voltage in which an AC voltage is superimposed is applied between the developing roller and the photosensitive member during development, the toner is driven by the AC voltage as it moves through the development gap. It is considered that the aggregate is crushed by the action of vibration force. As a result, a high-resolution image can be formed.

When the particle size distribution of the toner is broad, when an aggregate is formed by the addition of oil, a small particle size toner enters between the large particle size toners, and a large cohesive force acts together with the added fluorine oil or silicone oil. Therefore, even if a voltage on which an alternating voltage is superimposed is supplied, the image is not crushed, so that sufficient development cannot be realized.
Thus, flocculation body is easily crushed at the time of development, when the toner of less than a volume average particle diameter of 2 [mu] m ～4Myuemu, that bulk density is less than 0.25 g / cm ³ or more 0.35 g / cm ³ preferable.
When the bulk density is less than 0.25 g / cm ³ , sufficient toner is not transferred, and when it is 0.35 g / cm ³ or more, strong aggregates are formed. Therefore, both density and resolution are insufficient. .

Further, the particle size distribution is preferably sharp as 1 <Dv / Dn <1.1. If such particle size distribution is present, the bulk density will not be smaller than 0.25 g / cm ³ . preferable. The bulk density is a value measured according to JIS Z 7302-9.
Further, the liquid having a large negative chargeability such as silicone oil or fluorine oil covers the toner surface, so that the negative chargeability of the toner is stabilized and the developing process is stabilized.

Example 1
Synthesis of Resin 1 (Crosslinked Polyester Resin) In a 50 liter reaction kettle, raw materials such as an acid, an alcohol component and a catalyst having the following composition were put and reacted at 240 ° C. for 12 hours under a normal pressure nitrogen stream. . Thereafter, the pressure was reduced successively and the reaction was continued at 10 mmHg. The reaction was followed by the softening point based on ASTM E28-517, and the reaction was terminated when the softening point reached 160 ° C.
Terephthalic acid 3.9 parts by mass Isophthalic acid 9.06 parts by mass Ethylene glycol 2.54 parts by mass Neopentyl glycol 4.26 parts by mass Tetrabutyl titanate 0.1 parts by mass Epicron 830 0.3 parts by mass (Dainippon Ink and Chemicals, Inc. Bisphenol F type epoxy resin, epoxy equivalent 170 (g / eq)
Cardura E 0.1 parts by mass (Shell Japan alkyl glycidyl ester) epoxy equivalent 250 (g / eq)

The obtained polymer was a colorless solid, and had an acid value of 11.0, a glass transition temperature (Tg) of 60 ° C., and a softening point (T1 / 2) of 178 ° C.
In addition, the weight average molecular weight was determined by using a GPC measuring apparatus (HLC-8120GPC manufactured by Tosoh Corporation) as a separation column in combination with TSK-GEL G5000HXL / G4000HXL / G3000HXL / G2000HXL manufactured by Tosoh Corporation, column temperature: 40 ° C., solvent: tetrahydrofuran, solvent When measured at a concentration of 0.5 mass%, filter: 0.2 μm, flow rate: 1 ml / min and converted using standard polystyrene, the weight average molecular weight was 250,000.

Synthesis of Resin 2 (Linear Polyester Resin) In a 50 liter reaction kettle, raw materials such as acid, alcohol components and catalyst having the following composition were placed and reacted at 210 ° C. for 12 hours under a normal pressure nitrogen stream. It was. Thereafter, the pressure was reduced successively and the reaction was continued at 10 mmHg. The reaction was followed by the softening point according to ASTM E28-517 and terminated when the softening point reached 87 ° C.
Terephthalic acid 5.31 parts by mass Isophthalic acid 7.97 parts by mass Ethylene glycol 2.6 parts by mass Neopentyl glycol 4.37 parts by mass Tetrabutyl titanate 0.1 parts by mass

The obtained polymer was a colorless solid having an acid value of 10.0, a glass transition temperature (Tg) of 46 ° C, and a softening point (T1 / 2) of 95 ° C.
Further, when the molecular weight was measured in the same manner as the measurement of the molecular weight of Resin 1, it was a weight average molecular weight of 5200.

Preparation of wax master dispersion 1 30 parts by weight of carnauba wax (carnauba wax 1 manufactured by Hiroyuki Kato), 70 parts by weight of resin 2 which is a linear polyester resin prepared earlier and 150 parts by weight of methyl ethyl ketone Then, the mixture was refined with a star mill LMZ-10 (manufactured by Ashizawa Finetech) to prepare a wax master dispersion 1 having a solid content of 40% by mass. This composition is Resin 2 / Wax / Methyl ethyl ketone = 28/12/60.

Preparation of Colorant Master Chip 1C Cyan pigment (Dai Nippon Ink Chemical Co., Ltd. Cyan Pigment: Ket Blue111 CIPigment B-15: 3) 2000 parts by mass and linear polyester resin 2 2000 parts by mass, ST / AO stirring The mixture was put into a 20 L Henschel mixer (Mitsui Mining Co., Ltd.) equipped with a blade and stirred at 698 min ⁻¹ for 2 minutes to obtain a mixture. The mixture was melt-kneaded using an open-roll continuous extrusion kneader (Mitsui Mine Needex MOS140-800) to prepare a colorant master chip 1C.
Moreover, when the obtained master chip was diluted with Resin 2 resin and methyl ethyl ketone and observed with a 400 × optical microscope for the finely dispersed state of the colorant and the presence or absence of coarse particles, there were no coarse particles and the finely dispersed particles were uniformly dispersed. It was. The composition of the master chip was colorant / resin 2 = 50/50 by mass ratio.

Preparation of Colored Resin Solution 1 12.5 parts by weight of wax master dispersion 1, 4.2 parts by weight of colorant master chip 1C, 10.56 parts by weight of resin 1, 10.24 parts by weight of resin 2, and organic solvent 8.65 parts by mass of methyl ethyl ketone was added, the temperature was kept at 40 to 45 ° C., and the mixture was mixed for 2 hours at a stirring speed of 777 min ⁻¹ with a stirrer (Desper blade diameter 230 mm manufactured by Asada Iron Works), and dissolved and dispersed. Went.
Methyl ethyl ketone is further added to the resulting mixture to adjust the solid content to 65% by mass, and 0.22 parts by mass of dodecylbenzenesulfonic acid-based emulsifier (Neogen SC-F manufactured by Daiichi Kogyo Seiyaku) is added as an emulsifier. Then, a colored resin solution 1 containing a cyan pigment was prepared by dissolving and dispersing.

Transfer emulsification step 46.37 parts by mass (solid content 30 parts by mass) of the colored resin solution 1 was charged into a cylindrical container equipped with a stirrer (Desper made by Asada Iron Works) having a stirring blade with a blade diameter of 230 mm, and then a base As a functional compound, 5 parts by mass of 1N ammonia water was added, and after sufficiently stirring at 777 min ⁻¹ , the temperature was adjusted to 35 ° C.
Subsequently, the stirring speed was changed to 1100 min ⁻¹ and 37.25 parts by mass of water was added dropwise at a rate of 1.0 parts by mass / min. The peripheral speed of the stirring blade at this time was 13.2 m / s. As water was added, the viscosity of the system increased, but water was taken into the system at the same time as dropping, and stirring and mixing could be performed uniformly.

  In addition, a phase inversion point at which the viscosity rapidly decreased when 26 parts by mass of water was added was observed. Furthermore, after adding water, when the slurry was observed with an optical microscope, the resin was dissolved and a state where the colorant dispersoid and the wax dispersoid were dispersed was observed. No unemulsified material was observed. Since the colorant dispersoid and the wax dispersoid are stably dispersed in the aqueous medium, it is considered that the resin is adsorbed on the surface of the dispersoid. At this time, the state in the system was uniform, and generation of coarse particles due to the addition was not observed.

Combined process After the emulsion suspension obtained in the phase inversion emulsification process was transferred to a cylindrical container provided with a Max Blend blade (registered trademark) having a blade diameter of 340 mm, the stirring speed was maintained at 85 min ^-1. The temperature was adjusted to 25 ° C. Thereafter, the stirring speed was increased to 120 min ⁻¹ , and 12 parts by mass of a 3.5% by mass sodium sulfate aqueous solution was dropped at a rate of 1 kg / min as the first-stage electrolyte aqueous solution. Five minutes after the completion of the dropping, the stirring speed was lowered to 85 min ⁻¹ and stirring was performed for 5 minutes, and then the stirring speed was lowered to 65 min ⁻¹ and stirring was performed for 5 minutes. Subsequently, the stirring speed was reduced to 47 min ⁻¹ and stirring for 30 minutes was continued. The particle size at this time was 3 μm. After solid-liquid separation, toner mother particles were prepared by washing with water and drying.

Preparation of toner To 100 g of the obtained toner base particles, 2 parts by weight of negatively-charged silica silica fine particles RX200 (Nippon Aerosil, average particle size 10 nm, hexamethyldisilazane treatment), negatively-charged silica silica fine particles RX50 (Nippon Aerosil, average particle size) A toner of Sample 1 was prepared by adding 1.5 parts by weight of 50 nm, hexamethyldisilazane treatment) and stirring with a 1 liter stirrer at 10,000 rpm for 3 minutes.

Image formation test 100 g of toner of sample 1 is put in a color printer cartridge, and a development gap adjusting spacer with a thickness of 50 μm is used. A rectangular wave current with a peak-peak voltage of 1000 V and a frequency of 6000 Hz is superimposed on a DC voltage of −300 V. An image was formed by exposing the laser exposure means comprising a polygon mirror to the image forming apparatus shown in FIG. 1, which was modified to a line head type equipped with an organic EL light emitting element. The exposure output was 0.5 μJ / cm ² , and the exposure spot diameter (the diameter of the light amount that becomes 1 / e ² with respect to the peak light amount, where e is the base of the natural logarithm) was 20 μm. Other printing conditions were the same as those of LP-9000C manufactured by Seiko Epson.
Evaluation is performed by the following evaluation test method, and the results are shown in Table 1, Table 2, and Table 3.

Evaluation test method 1. Toner particle size Volume average particle size Dv and number average particle size Dn were measured with a flow particle image analyzer (PFIA-2100 manufactured by Sysmex).
2. The bulk density of the toner was measured according to JIS Z 7302-9.
3. Development efficiency The development efficiency is expressed by expressing the amount of development on the photoconductor and the amount of toner on the developing roller by sticking the toner to an adhesive tape and measuring the mass, and the ratio to the amount of toner on the developing roller expressed as 100 fractions. It is shown in 1.
Table 2 shows the development efficiency and the ratio of the volume average particle diameter Dv to the number average particle diameter Dn.
3. Development unevenness A solid 30% density image was formed on A3 size electrophotographic plain paper, the OD values at 20 arbitrary locations were measured, and the average of the OD values with respect to the maximum OD value was expressed in terms of 100 minutes. Shown in
4). Change test of printed dot diameter The size of the printed dot after printing 2000 sheets on the A4 size plain electrophotographic paper when printing with an exposure spot of 20 μm diameter and after printing 10000 sheets was measured with a digital optical microscope (Keyence). VH-8000) was observed at 450 times and it was observed whether the part exposed at 20 μm had a diameter of 20 μm even on paper.
The results are shown in Table 3.

Example 2
The amount of dimethyl silicone oil (KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd.) was changed with respect to the toner of sample 1, and the toner of sample 2 and sample 7 was prepared by stirring at 10000 rpm for 3 minutes with a stirrer. An evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.
For the toner of Sample 4, a change test of the print dot diameter was performed, and the results are shown in Table 2.

Example 3
The toner of Sample 8 was prepared in the same manner as in Example 2 by adding 0.5 part by mass of fluorine oil (perfluoropolyether: Barrietta J 25 V manufactured by NOK) to 100 parts by mass of the toner of Sample 1. A change test of the printed dot diameter was conducted in the same manner as in Example 1, and the results are shown in Table 3.

Comparative Example 1
In the coalescence process of Example 1, coalescence was performed in the same manner except that 3.5 parts by mass of a sodium sulfate aqueous solution of 3.5% by mass was dropped as the first-stage electrolyte aqueous solution, respectively. And evaluation were performed to obtain toners having particle diameters of 1.9 μm, 2.9 μm, and 3.5 μm.
The toner of Sample 9 was prepared in the same manner as in Example 1, and a change test of the printed dot diameter was performed in the same manner as in Example 1. The results are shown in Table 4.

Comparative Example 2
Following the coalescence process of Example 1, coalescence was performed in the following second-stage coalescence process.
Second stage coalescence process The stirring speed was adjusted to 120 min ⁻¹ , and 2 parts by mass of sodium sulfate aqueous solution having a concentration of 5 mass% was dropped at a rate of 1 kg / min as the second stage electrolyte. After 5 minutes from the end of dropping, the stirring speed was adjusted to 85 min ⁻¹ and stirring was continued for 5 minutes, and then the stirring speed was reduced to 65 min ⁻¹ and stirring was performed for 5 minutes. Subsequently, the stirring speed was adjusted to 47 min ⁻¹ and stirring for 20 minutes was continued.
The toner of Sample 10 was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The particle size was 4.1 μm.

Comparative Example 3
In the first step coalescence process of Example 1, coalescence and evaluation were performed in the same manner except that 12 parts by mass of an aqueous sodium sulfate solution was dropped at a rate of 3 kg / min. Dv / Dn = 1 .15.

Next, 0.5% by mass of dimethyl silicone oil (KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the toner of Sample 11 was prepared by stirring at 10000 rpm for 3 minutes with a stirrer, and development efficiency evaluation test The results are shown in Table 2.
Comparative Example 4
In the first step coalescence process of Example 1, coalescence and evaluation were performed in the same manner except that 12 parts by mass of the aqueous sodium sulfate solution was dropped at a rate of 6 kg / min. Dv / Dn = 1 .25.

  Next, 0.5% by mass of dimethyl silicone oil (KF-96-200CS manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the toner of Sample 12 was prepared by stirring at 10,000 rpm for 3 minutes with a stirrer, and an evaluation test of development efficiency The results are shown in Table 2.

FIG. 1 is a diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 2 is a diagram for explaining the image forming mechanism of the present invention, FIG. 2A is a diagram for explaining the image forming unit explained in FIG. 1 in an enlarged manner, and FIG. It is a figure explaining a process. 3A and 3B are diagrams for explaining the developing means of the present invention, FIG. 3A is a side view, and FIG. 3B is an enlarged cross-sectional view of one end portion of the developing roll. FIG. 4 is a perspective view for explaining an example of the exposure means of the present invention. FIG. 5 is a cross-sectional view of the exposure unit shown in FIG. 4 in the sub-scanning direction. FIG. 6 is a diagram illustrating a light emitting element group including a plurality of light emitting elements.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Housing, 3 ... Paper discharge tray, 4 ... Power supply unit, 5 ... Control unit, 6 ... Image forming unit, 61, 61Y, 61M, 61C, 61K ... Photoconductor, 61S ... Photoconductor surface 62 ... Intermediate transfer belt, 63 ... Drive roller, 64 ... Secondary transfer roller, 65 ... Stretching roller, 66 ... Cleaner section, 67 ... Cleaner blade, 68 ... Waste toner collecting means, 7 ... Fixing unit, 71 ... Heating roller, 72 ... backup roller, 8 ... paper feeding unit, 81 ... paper feeding cassette, 82 ... pickup roller, 83 ... roller pair, 100 ... developing means, 101 ... developing roller, 102 ... supply roller, 103 ... regulating blade, 104: Toner collecting means, 105 ... Charging means, 106, 106A, 106B ... Spacer, 107 ... Adhesive layer, 108 ... Prevention of horizontal dimension fluctuation G: Development gap, 200: Exposure means, 201: Line head, 202 ... Case, 203 ... Positioning pin, 204 ... Insertion hole for fixing member, 205 ... Micro lens array, 206 ... Light shielding member, 207 ... Substrate, 208 ... light emitting element, G208 ... light emitting element group, L208 ... light emitting element group row, U208, U208A1, U208B1 ... light emitting element unit, 209 ... light guide hole, 210 ... fixing device, 211 ... back cover, 212 ... sealing member, 213 , 213A, 213B ... micro lens

Claims (6)

A toner having a volume average particle diameter of 2 μm or more and less than 4 μm and having a ratio of the volume average particle diameter to the number average particle diameter of 1 to 1.1 is placed on the outer side in the axial direction of the toner conveying surface of the developing roller. As a spacer for setting a development gap in contact with the surface, a material that swells due to moisture absorption is larger than the surface constituting member of the developing roller, and an AC superimposed voltage is applied to the photosensitive member for development. Developing method. 2. The developing method according to claim 1, wherein the toner is partially agglomerated by adding 0.05% by mass or more and less than 2% by mass of silicone oil or fluorine oil to the toner. A toner having a volume average particle diameter of 2 μm or more and less than 4 μm and having a ratio of the volume average particle diameter to the number average particle diameter of 1 to 1.1 is placed on the outer side in the axial direction of the toner conveying surface of the developing roller. As a spacer for setting the developing gap by contacting the surface of the developing roller, a material that swells by moisture absorption is larger than that of the surface constituting member of the developing roller. In this exposure, a lens array in which light emitted from a plurality of light emitting elements corresponding to one lens forms an image on a photosensitive member, and the lens array having a plurality of rows extending in the main scanning direction is used. And forming an image by forming an exposure spot having a diameter of 15 to 40 [mu] m on the photoconductor. 4. The image forming method according to claim 3, wherein the toner is partially agglomerated by adding 0.05% by mass or more and less than 2% by mass of silicone oil or fluorine oil to the toner. A developing roller that conveys toner having a volume average particle diameter of 2 μm or more and less than 4 μm and having a ratio of the volume average particle diameter to the number average particle diameter of 1 to 1.1; A developing means to which an AC superimposed voltage is applied on the outside in the direction, which is made of a member that swells due to moisture absorption more than the surface constituting member of the developing roller, and is provided with a spacer that contacts the photosensitive member to set a developing gap. The photoconductor exposure means has a lens array in which light emitted from a plurality of light emitting elements corresponding to one lens forms an image on the photoconductor, and the lens array has a plurality of rows extending in the main scanning direction. And an exposure spot having a diameter of 15 to 40 μm is formed on the photosensitive member. 5. The image forming apparatus according to claim 4, wherein the toner is partially agglomerated by adding 0.05% by mass or more and less than 2% by mass of silicone oil or fluorine oil to the toner.

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