JP2010139986A - Image forming method, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method for restraining occurrence of a very small flaw as well while restraining occurrence of toner filming to obtain a uniform image. <P>SOLUTION: A non-magnetic single component toner containing wax component is used as a developer 5. The universal hardness on the surface of a photoreceptor drum 1 is 185-220 N/m<SP>2</SP>and the elastic deformation rate is 40-50%. Image formation is performed with the adhesive strength of external additive material in the developer set to 45-65%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method, an image forming apparatus such as a copier, a printer, a facsimile machine, a plotter, and a multifunction machine including at least one of these, and a detachable to the image forming apparatus. It relates to a process cartridge.

Conventionally, electrophotographic technology has been widely used and used in printers connected to facsimile machines and personal computers. Recently, digital recording technology has been applied to not only printers but also ordinary copying machines. As the development progresses, the demand tends to increase more and more in the future.
In such a digital copying machine, it is required to extend the life of the apparatus from the viewpoint of efficient use of the office environment for the purpose of improving the image forming speed, improving the image quality, reducing the size, reducing the noise, and reducing the environmental load. .
In addition, the use of digital copiers in small working groups such as small offices and home offices has increased, and miniaturization design tends to be emphasized especially at low cost.

2. Description of the Related Art Today, electrophotographic apparatuses are being colorized, such as color copiers and color printers, according to market demands. A color electrophotographic apparatus is a so-called revolver type device that includes a developing device of a plurality of colors around one photoconductor, forms a color image on the photoconductor, and transfers the toner image to form a color image. A so-called tandem type that forms a color image by forming a single-color image and arranging them side-by-side and transferring each single-color image in sequence by forming a separate developing device on the photoconductor is widely used. It has been.
Since the revolver type uses only one photoconductor, it is relatively advantageous to reduce the size of the apparatus, but it is disadvantageous to increase the speed because it requires image formation a plurality of times. On the other hand, the tandem type is large in size, but is advantageous for speeding up.
In recent years, a tandem type image forming apparatus has attracted attention because a color image forming apparatus is required to have a speed equivalent to monochrome.

As shown in FIG. 1 (schematic configuration diagram of the image forming apparatus in the embodiment of the present invention), the tandem type image forming apparatus has a photosensitive drum 1 as an image carrier that can be driven to rotate freely. First, the surface of the photosensitive drum 1 is uniformly charged by the charging device 2 as a charging means.
Next, a laser beam 3 is irradiated by an exposure optical system (exposure means), the surface of the photosensitive drum 1 is exposed to form an electrostatic latent image on the photosensitive drum, and then inside the developing device 4 as a developing means. The developer 5 is moved to the surface of the photosensitive drum 1 to form a visible image on the photosensitive drum 1.
Next, at a contact portion between the intermediate transfer belt 6 as a transfer target and the photosensitive drum 1, a primary transfer roller 7 as a primary transfer means provided inside the intermediate transfer belt 6 at the contact portion. Thus, the developer 5 on the surface of the photosensitive drum 1 is transferred to the surface of the intermediate transfer belt 6. The transferred developer is transferred onto a paper (transfer paper, recording paper) P by a secondary transfer roller 8 as a secondary transfer means, and then supplied to a fixing device 9 to fix a toner image on the paper. .
On the other hand, the developer 5 remaining on the surface of the photosensitive drum 1 is cleaned and removed by a cleaning blade 11 as an elastic blade in a cleaning device 10 as a cleaning unit in preparation for the next image formation.
Cleaning devices include those that use fur brushes and magnetic brushes, and those that use a cleaning blade.However, because of its simple structure and low cost, the cleaning blade removes residues adhering to the surface of the photoconductor. Scraping type cleaning devices are widely used.

In such a market background, a toner as a developer is often a non-magnetic one component from a low cost viewpoint, and in this case, an external additive component mainly composed of a silica component that assists charging properties, Because of its compact design, it incorporates a component that assists glossiness, such as wax, to eliminate the need for fixing oil. However, when the wax component or the like is included in the toner in this way, a stirring mechanism is provided to maintain the fluidity of the toner in the developing unit, or the toner is regulated to form a certain amount of toner layer like a developing blade. When physical stress is applied to the toner by a member or the like, the wax component oozes out from the toner surface, so that the cohesive force between the toners is increased and the toner is easily solidified, so that the toner is easily fixed to the constituent member.
In order to prevent this, the external additive component is applied to the base surface of the toner and the toner is designed to maintain fluidity between the toners. However, the external additive has a particle size significantly larger than that of the toner base. Since the external additive component is detached from the base material due to the physical stress described above, if the free external additive component adheres to the photoconductor, it is difficult to remove it from the photoconductor by the cleaning member.
Externally added components and the like attached to the photoreceptor are pressed and hardened by a cleaning blade or other contact member, and are agglomerated and fixed on the photoreceptor to cause a so-called filming phenomenon. When the photosensitive member is filmed, the surface of the photosensitive member at the filmed portion is not exposed and white spots are generated on the image, and scratching the contact member may cause image abnormalities such as streaks and spots.

Various attempts have been made to prevent filming on the photoreceptor for the purpose of obtaining good image quality.
For example, in Patent Document 1, a solid lubricant made of zinc stearate or the like is pressed against a brush roller having good polishing and coating properties with a pressure spring, and the solid lubricant is scraped near the tip of the brush roller. The configuration to be held is described. The brush roller is fixed at a position where the vicinity of the brush tip rotates by rubbing the surface of the photoconductor, and the lubricant held by rubbing the surface of the photoconductor is applied to the surface of the photoconductor.
Applying a lubricant to the photoconductor as described above reduces the coefficient of friction of the photoconductor, suppresses excessive blade vibration by increasing the sliding property, prevents scratches by reducing stress on the photoconductor, silica, etc. We are trying to achieve stable image quality by suppressing filming due to prevention of adhesion of external additives.

However, these require a separate lubricant application mechanism, which is very expensive and requires extra layout, and the equipment becomes larger, so it can be used in small offices, home offices, etc. It is not suitable for a small layout and does not meet user needs.
As described in Patent Document 2, as one of lubricant applying means for applying a lubricant such as zinc stearate to the surface of the photoreceptor, a toner containing zinc stearate in the toner is used. It is known that zinc stearate is supplied simultaneously with the formation of a toner image.
This is an attempt to add the lubricant itself to the toner to ensure the slipperiness of the surface of the photoreceptor, but there is a problem that the lubricant itself has a smaller particle size than the toner and is inferior in cleaning properties.

The photoconductor has also been studied for filming resistance. As the binder resin for the organic photoreceptor, bisphenol A type polycarbonate resin is most commonly used.
However, when a photosensitive layer is formed using a bisphenol A type polycarbonate resin as a binder resin, there are disadvantages such as the coating solution for the photosensitive layer being unstable. Therefore, there is a demand for a charge transfer layer material that does not have such a drawback.
On the other hand, in consideration of the stability of the coating solution, it has also been proposed to use a bisphenol Z-type polycarbonate resin as a material for the photosensitive layer of the electrophotographic photosensitive member. However, when the electrophotographic photosensitive member using the bisphenol Z-type polycarbonate resin is mounted on an electrophotographic apparatus and the electrophotographic process is repeated, a problem of toner filming occurs on the surface of the electrophotographic photosensitive member.

Thereafter, polycarbonate copolymers having the bisphenol A type and Z type structures and various other polycarbonate copolymers have been proposed (for example, Patent Document 3).
When the electrophotographic photosensitive member is mounted and operated in an electrophotographic apparatus, toner filming on the surface of the photosensitive member becomes a problem. In the slip stick cleaning system, the harder the photoreceptor surface, the better the cleaning property and the less the toner filming.
In view of such requirements, a polycarbonate copolymer resin that is harder and more effective for toner filming has been proposed (for example, Patent Document 4). There has also been proposed an electrophotographic apparatus equipped with an electrophotographic photosensitive member using these resins (for example, Patent Document 5).
However, when a charge transfer agent is added to these hard polycarbonate copolymer resins, they are hard but brittle, and when this electrophotographic photosensitive member is mounted on an electrophotographic apparatus and the electrophotographic process is repeated, minute scratches are observed. There was a problem that occurred. The image quality is uneven around the small scratches.

JP 2000-231298 A Japanese Patent Laid-Open No. 11-184340 JP-A-6-59471 JP 2001-206943 A JP 2006-65155 A

  As described above, it is a difficult problem to obtain a uniform image to suppress the generation of minute scratches while suppressing the occurrence of toner filming.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method, an image forming apparatus, and a process cartridge capable of suppressing the occurrence of toner filming and suppressing the generation of minute scratches and obtaining a uniform image. And

In order to achieve the above object, according to the first aspect of the present invention, a charging means for uniformly charging the image carrier and the surface of the uniformly charged image carrier are exposed to form an electrostatic latent image. Exposure means for performing, developing means for forming a formed electrostatic latent image on the image carrier with a developer, transfer means for transferring an image on the image carrier to a transfer target, In an image forming apparatus having a cleaning unit that mainly removes the developer remaining on the image bearing member after the transfer with an elastic blade, a nonmagnetic one-component toner containing a wax component is used as the developer. And the universal hardness of the surface of the image carrier is 185 to 220 N / m ² , the elastic deformation rate is 40 to 50%, and the adhesion strength of the external additive material in the developer is 45 to 65%. It is characterized by.

  According to a second aspect of the present invention, in the image forming method according to the first aspect, the electrophotographic photosensitive member as the image carrier is at least the structural formula (1) and the structural formula (2) as a binder resin in the photosensitive layer. The weight ratio of the polycarbonate copolymer resin A and the polycarbonate resin B is 30: The range is from 70 to 70:30.

（構造式１中、Ｒ_１とＲ_２は、各々独立に水素原子、ハロゲン原子、炭素数１〜６の置換無置換のアルキル基を表す。）

(In Structural Formula 1, R ₁ and R ₂ each independently represent a hydrogen atom, a halogen atom, or a substituted and unsubstituted alkyl group having 1 to 6 carbon atoms.)

According to a third aspect of the present invention, in the image forming method according to the second aspect, the charge generating agent in the photosensitive layer is Y-type oxytitanium phthalocyanine.
According to a fourth aspect of the present invention, in the image forming method according to the second or third aspect, the charge transfer agent in the photosensitive layer is a distyryl charge transfer agent represented by the general structural formula (4). To do.

（一般構造式４中、Ｒ_３〜Ｒ_５は、各々独立に水素、ハロゲン原子、置換基を有してもよい炭素数１〜６のアルキル基、アルコキシ基、炭素数６〜１２の置換若しくは無置換のアリール基を表す。）

(In General Structural Formula 4, R _{3 to} R ₅ are each independently hydrogen, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, an alkoxy group, a substituted group having 6 to 12 carbon atoms, or Represents an unsubstituted aryl group.)

According to a fifth aspect of the present invention, in the image forming method according to any one of the second to fourth aspects, the photosensitive layer includes, as additives, a phenol-based antioxidant, an amine-based antioxidant, and a benzotriazole-based ultraviolet absorber. It is characterized by including.
The invention according to claim 6 is characterized in that, in the image forming method according to any one of claims 2 to 5, the components of the photosensitive layer are dissolved and tetrahydrofuran is used as a solvent for forming the photosensitive layer. To do.
According to a seventh aspect of the present invention, in the image forming method according to any one of the first to sixth aspects, the developer is a pulverized toner.

The invention according to claim 8 is the image forming method according to any one of claims 1 to 7, wherein the developer contains 3 to 10% of a wax component.
According to a ninth aspect of the present invention, in the image forming method according to any one of the first to eighth aspects, the developer contains 0.5 to 4.0% of an external component.
According to a tenth aspect of the present invention, in the image forming method according to any one of the first to ninth aspects, the aggregation degree of the developer is 5 to 70%.

According to an eleventh aspect of the present invention, in the image forming method according to any one of the first to tenth aspects, the adhesion force between the toners of the developer is 45 to 55 g.
According to a twelfth aspect of the present invention, in the image forming method according to any one of the first to eleventh aspects, a hardness specified by JIS-A of the elastic blade is 60 to 80 °.
According to a thirteenth aspect of the present invention, in the image forming method according to any one of the first to twelfth aspects, the resilience of the elastic blade is 35 to 55%.

According to a fourteenth aspect of the present invention, in the process cartridge, the image carrier, the developer, and the cleaning unit in the image forming method according to any one of the first to thirteenth aspects are integrally provided. .
According to a fifteenth aspect of the present invention, in the image forming apparatus, the image forming method according to any one of the first to thirteenth aspects can be carried out.

According to the present invention, in an image forming method using a one-component toner containing a wax, even when an external additive material such as silica is added to prevent toner aggregation, adhesion of the silica component added externally to the base material is prevented. By optimizing the strength, the toner was subjected to physical stress such as toner regulation pressure applied to form a toner layer uniformly on the developing blade in order to suppress stirring in the developing machine applied to the toner and image density unevenness. Even in this case, separation of external components such as silica can be prevented.
However, if the adhesive strength is too high, the external additive material will be buried in the base material, causing the toner to lose its fluidity and causing non-uniformity due to non-uniform agglomeration and toner layers. It becomes.
In addition, by optimizing the hardness and elastic deformation rate on the surface of the photoreceptor, which is an image carrier, not only can the fine scratches caused by the physical stress from the cleaning or developing blade be prevented, but also the cleaning blade. By making the behavior of the edge active, it becomes possible to discharge toner components in the vicinity of the edge, and filming on the photosensitive member can be prevented. If the hardness and elastic deformation rate are too large, the blade tip behavior becomes excessive, and there is a risk of causing fatal defects such as blade chatter noise and blade blistering. On the other hand, if it is too small, the silica component and the like will enter the scratches formed on the photoconductor, which causes the photoconductor filming. End up.

According to the present invention, since the hardness and elastic deformation rate of the surface of the photoreceptor can be set to appropriate values, it is possible to obtain good image quality without filming on the photoreceptor.
Y-type oxytitanium phthalocyanine has a high sensitivity characteristic as a charge generator for an inexpensive laser wavelength of 780 nm, and has good compatibility with the charge transport material in the present invention and is highly effective.
According to the present invention, it is possible to provide a photoreceptor having good compatibility with a resin and strong environmental resistance with the present charge transfer agent.
According to the present invention, the characteristics, mechanical characteristics, and durability of the photoreceptor can be improved.
According to the present invention, the solubility of the binder resin and the charge transfer agent and the stability of the produced solution can be achieved with tetrahydrofuran. Also, it is easy to use with no halogen from the viewpoint of environmental load.
According to the present invention, in the case of pulverized toner, since the toner circularity is small and the toner dammed up by the cleaning blade is difficult to roll, it is difficult for the toner to enter the gap between the blade and the surface of the photosensitive member, so that the blade is unlikely to slip through.

According to the present invention, the fluidity of the toner and the gloss of the image can be controlled by controlling the content of the wax component. If the wax component is too large, the fluidity of the toner decreases, the degree of aggregation of the toner is large, and the toner adheres to the photoreceptor, causing filming. On the other hand, if it is too small, the image quality deteriorates due to insufficient gloss.
When the amount of the external additive is large, the amount of adhesion to the surface area of the toner base becomes large, so that the external additive is easily detached from the base and is released, which causes filming. Conversely, if it is too small, filming is unlikely to occur, but due to insufficient toner fluidity, the supply of toner to the developing blade becomes insufficient, and image abnormalities such as density unevenness are likely to occur. According to the present invention, these problems can be solved.
According to the present invention, by optimizing the degree of aggregation, aggregation fixation on the photoreceptor can be suppressed, and filming can be prevented.
If the adhesion force between the toners is large, the particle behavior in the part where the stress is applied in the actual machine is not stable, so the adhesion between the particles is increased on the photoconductor, which causes filming. This problem can be solved.

If the hardness of the cleaning blade is too high, the peak pressure on the surface of the photoconductor is large, and scratches are given to the surface of the photoconductor. Therefore, the toner on the photoreceptor or the free external additive enters the scratch and causes filming.
On the other hand, if the hardness is too small, the toner's stopping power is weak and the free external additive is likely to rub off, and the toner tends to clump together due to the stress at the nip portion of the blade and the photoreceptor, causing filming. Become. According to the present invention, these problems can be solved.
When the rebound resilience of the cleaning blade increases, the frictional vibration at the blade edge tip becomes excessive, so that the toner or free external additive is easily rubbed off, and filming and the like are likely to occur. On the other hand, if the rebound resilience is too small, the film repelling force (slipstick) is small and the toner tends to rub off, and filming is likely to occur. According to the present invention, these problems can be solved.

Embodiments of the present invention will be described below with reference to the drawings.
The outline of the configuration of the tandem type image forming apparatus according to the present embodiment is as described above with reference to FIG. Supplementally, as shown in FIG. 1, the configuration around the photosensitive drum 1 described above is the same for each color (yellow: Y, magenta: M, cyan: C, black: Bk) along the intermediate transfer belt 6. Are arranged on the intermediate transfer belt 6 in the order of the colors and transferred onto the transfer sheet as a transfer target at the secondary transfer site. The color order here is an example and is not limited.

Based on FIG. 2, the peripheral configuration of each photosensitive drum 1 will be described in detail. Around the photosensitive drum 1, there are a charging device 2 for charging the drum surface, an exposure means (not shown) for emitting a laser beam 3 for forming a latent image on the uniformly charged surface, and a latent image on the drum surface. A developing device 4 that forms a toner image by adhering charged toner, a primary transfer roller 7 as a transfer device that transfers the formed toner image on the drum to the transfer target, and residual toner on the drum. The cleaning device 10 and the neutralization device 27 for removing the residual potential on the drum are sequentially arranged.
In tandem type electrophotography, monochromatic images such as black, magenta, cyan and yellow are mainly formed on the surface of the photoreceptor. In such a configuration, when image formation is performed by the negative positive method (lowering the exposure portion potential and attaching the toner), the photosensitive drum 1 whose surface is uniformly negatively charged by the charging roller 22 of the charging device 2. , An electrostatic latent image is formed on the surface of the photosensitive member by the exposure light 3, and a toner 5 is attached to the surface of the photosensitive member by the developing device 4 to visualize the image.

The toner image is transferred from the surface of the photosensitive drum 1 by the transfer device 25 including the intermediate transfer belt 6 and the primary transfer roller 7, and the residual toner component that has not been transferred from the photosensitive drum 1 to the intermediate transfer belt 6. Is removed from the surface of the photoreceptor by the cleaning device 10.
The toner image transferred to the surface of the intermediate transfer belt is transferred to a recording sheet conveyed from a paper feed tray (not shown) by applying a bias to the secondary transfer roller 8 at a secondary transfer unit (not shown). The residual toner component or the external additive component after the transfer is removed by the cleaning device 10.
The toner image on the unfixed recording paper is fixed on the recording paper by the fixing device 9. The photosensitive drum 1 from which the residual toner has been removed has its residual potential canceled by the charge eliminating lamp 27 and is used for the next image forming process.
In FIG. 2, reference numeral 15 denotes a process cartridge that is detachably attached to an image forming apparatus main body (not shown).

The charging device 22 uses a contact roll charging method in which a high voltage is applied to the core of the charging roller 22 disposed in contact with the photosensitive drum 1 to uniformly charge the surface of the photosensitive member. A corotron that discharges by applying a high voltage, a scorotron system, and a charging brush, a charging sheet, a needle electrode, and the like can also be used.
These have the advantage of being less susceptible to cleaning because they can charge the surface of the photoconductor without contact with the photoconductor, but the amount of discharge products such as ozone and NOx that are generated with the discharge. However, there is a problem in terms of durability of the photosensitive member because it is much larger than the charging roll method.
As the transfer device 25, an intermediate transfer belt method is used, but other known devices such as a charge wire, a transfer roller, a needle electrode, and a transfer drum can be used.

FIG. 3 is a detailed explanatory view of the cleaning device 10. In FIG. 3, a cleaning device 10 used for cleaning the toner attached to the surface of the image carrier 1 includes a toner collection container 33 and a toner collection container 33 for scraping and removing the toner attached to the image carrier 1. The toner that is supported in the toner collection container 33 by screwing or the like and can be rotated in the same direction as the image carrier 1, and the toner scraped off from the surface of the image carrier 1 by the contact of the cleaning blade 11 is contained in the toner collection container 33. And a screw 38 to be transferred.
As a means for pressing the cleaning blade 11 against the image carrier, a means for supporting the cleaning blade 11 by fixing it to the case is shown. However, an external force such as a spring pressure contact may be applied instead of fixing to bias the pressure contact force.
The cleaning blade 11 includes a plate-like elastic blade 11a and a support member 11b that supports the plate-like elastic blade 11a. The elastic blade 11a is bonded to the support member 11b in the longitudinal direction.

The blade for blade cleaning in the cleaning device 10 is obtained by attaching an elastic blade 11a made of a plate-like material such as a plate-like polyurethane to a support member 11b, and is configured to press contact with the surface of the electrophotographic photosensitive member. Yes.
Therefore, to increase the toner cleaning accuracy, it is effective to increase the contact pressure of the blade to the electrophotographic photosensitive member. However, if the contact pressure is too large, the behavior of the blade tip increases and the blade chatter is increased. When the sound or frequency resonates with the natural frequency of the photoreceptor, unpleasant noise is generated.
As a form of contact of the blade with the electrophotographic photosensitive member, there are a forward direction with respect to the rotation direction of the electrophotographic photosensitive member and a counter direction. From the standpoint of cleaning accuracy, the latter counter direction contact form is more preferable.
The contact method in the counter direction that improves the cleaning accuracy raises the peak contact pressure of the blade to the photosensitive member when the photosensitive member rotates, causing an increase in the frictional force between the two.
As a result, the durability deteriorates due to an increase in the amount of shaving of the photoreceptor, the occurrence of scratches on the electrophotographic photoreceptor, the occurrence of cleaning failure due to turning up of the contact portion between the blade and the photoreceptor, and the apparatus by the blade entrainment in the downstream direction of the photoreceptor This may lead to problems such as stoppage and damage.

The hardness of the cleaning blade (elastic blade) is 60 ° to 80 °, and more preferably 65 ° to 75 °. If the hardness is 60 ° or less, the blade edge is worn due to contact friction with the photoreceptor, and the toner blocking force is reduced. On the other hand, if the blade is 80 ° or more, it is too hard to damage the surface of the photoreceptor, and the edge resistance of the blade is deteriorated, resulting in problems such as poor cleaning.
Here, the hardness of the cleaning blade (elastic blade) is defined by the hardness test of JIS K6253.
The rebound resilience of the cleaning blade (elastic blade) is 35 to 55% at 25 ° C., and more preferably 35 to 45%. If the rebound resilience is 35% or less, the force to push back the toner dammed by the cleaning blade is insufficient, and as the durability progresses, the dammed toner pushes the blade back and the toner slips through. On the other hand, if the impact resilience exceeds 55%, the behavior of the blade tip increases, and the blade squeals particularly at high temperatures.

Here, the rebound resilience of the cleaning blade (elastic blade) is defined by a rebound resilience test of JIS K6255.
As long as the cleaning blade has the above physical properties, the material, shape, structure, size and the like are not particularly limited, and can be appropriately selected according to the purpose. Examples of the shape of the cleaning blade (elastic blade) include a rectangular plate shape. There is no restriction | limiting in particular as said material, According to the objective, it can select suitably, For example, it is preferable to form with a natural rubber and a polyurethane (specifically the organic compound which has a urethane bond at least) material. As is well known, the polyurethane is obtained by a reaction between an isocyanate compound and a polyol compound.

Examples of the isocyanate compound include tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, tolidine diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like. Is mentioned.
There is no restriction | limiting in particular as said polyol compound, According to the objective, it can select suitably, For example, polyether polyol, polyester polyol, acrylic polyol, epoxy polyol, etc. are mentioned. Examples of the raw material monomer constituting the acrylic polyol include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. , Isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, acrylic acid, methacrylic acid, maleic acid, itaconic acid, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate Acrylamide, N-methylol acrylamide, diacetone acrylamide, glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, and the like.

FIG. 4 is a cross-sectional view showing a configuration example of the photosensitive drum (electrophotographic photosensitive member) 1. A function-separated electrophotographic photosensitive member in which a charge generation layer 32 containing at least a charge generation agent is formed on a conductive support 31, and a charge transfer layer 33 containing at least a charge transfer agent is formed thereon. Applies.
In this case, the photosensitive layer 30 is formed by the charge generation layer 32 and the charge transfer layer 33.
Various methods can be used as a method for forming the charge generation layer 32. For example, a coating solution in which an oxytitanium phthalocyanine pigment is used as a charge generation agent and dispersed or dissolved in a suitable solvent together with a binder resin is used. It can apply | coat on the support body used as the foundation | substrate of this, and can dry and form as needed.
The charge transfer layer 33 has at least the charge transfer agent of the present invention, which will be described later. For example, the charge transfer layer 33 is formed by binding the charge transfer agent on the charge generation layer 32 as a base using a binder resin. It can be formed by wearing.
Various methods can be used as a method for forming the charge transfer layer 33. In general, a coating solution in which a charge transfer agent is dispersed or dissolved in a suitable solvent together with a binder resin is used as a base charge generation layer. The method of apply | coating and drying can be used.
Further, the present invention can also be applied to an inversely stacked electrophotographic photosensitive member in which the charge generation layer 32 and the charge transfer layer 33 are stacked upside down. Furthermore, the present invention can also be applied to a single layer type electrophotographic photosensitive member containing a charge generating agent and a charge transfer agent in the same layer. Further, an intermediate layer may be provided between the conductive support 31 and the charge generation layer 32 as necessary, or a protective layer may be provided on the photosensitive layer 30.

Examples of the conductive support 31 that can be used in the present invention include simple metals such as aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum, indium, and alloys thereof. A processed body is mentioned. The shape may be any shape as long as it is flexible, such as a sheet shape, a film shape, and a belt shape, and may be endless or endless.
The diameter of the conductive support 31 is particularly effective when it is 60 mm or less, preferably 30 mm or less.
Among these, aluminum alloys such as JIS 3000, JIS 5000, and JIS 6000 are used, and general methods such as EI (Extension Ironing) method, ED (Extension Drawing) method, DI (Drawing Ironing) method, II (Impact Ironing) method, etc. A conductive support formed by a method is preferred, and the surface of the conductive support is further subjected to surface treatment such as diamond cutting or polishing, surface treatment such as anodizing treatment, or these treatments and treatments. Anything such as a non-cutting tube may be used.

Moreover, when using resin as a base | substrate, conductive agents, such as metal powder and conductive carbon, can be contained in resin, and conductive resin can also be used as base | substrate formation resin. Further, when glass is used for the substrate, the surface thereof may be coated with tin oxide, indium oxide, or aluminum iodide so as to have conductivity.
Further, an intermediate layer may be formed on the support. This intermediate layer has an adhesion improving function, a barrier function for preventing an inflow current from the aluminum tube, a defect covering function on the surface of the aluminum tube, and the like. Various resins such as polyethylene resin, acrylic resin, epoxy resin, polycarbonate resin, polyurethane resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, polyamide resin, nylon resin, alkyd resin, and melamine resin are used for this intermediate layer. be able to. These resin layers may be composed of a single resin or a mixture of two or more resins. Moreover, a metal compound, carbon, silica, resin powder, etc. can be dispersed in the layer. Furthermore, various pigments, electron accepting substances, electron donating substances, and the like can be contained for improving the characteristics.

These intermediate layers can be formed using an appropriate solvent, dispersion, and coating method in the same manner as the photosensitive layer. The film thickness of the intermediate layer is 0.1 μm to 50 μm, preferably 0.5 μm to 20 μm.
As a charge generating agent that can be used in the present invention, oxytitanium phthalocyanine is desirable since it has high sensitivity characteristics. Among them, Y-type oxytitanium phthalocyanine in the X-ray diffraction peak diagram shown in FIG. Good compatibility in combination.
These charge generating agents may be used alone or in combination of two or more in order to obtain an appropriate photosensitivity wavelength and sensitizing action. The film thickness of the charge generation layer is 0.01 to 5 μm, preferably 0.1 to 2 μm.

  Next, as a binder resin used in the photosensitive layer of the present invention, a polycarbonate copolymer resin A containing a repeating unit represented by the general structural formula (1) and the structural formula (2), and a structural formula (3) Both of the polycarbonate resin B represented are included.

In General Structural Formula 1, R ₁ and R ₂ each independently represent a hydrogen atom, a halogen atom, or a substituted and unsubstituted alkyl group having 1 to 6 carbon atoms.

It is appropriate that the polycarbonate copolymer resin A: the polycarbonate resin B (weight ratio) is in the range of 30:70 to 70:30, and the ratio of the polycarbonate copolymer resin A is smaller than the above range. It becomes easy to cause toner filming on the surface of the photoreceptor. On the other hand, if the size is increased, the surface of the photoconductor is minutely scratched, resulting in a non-uniform image.
In the polycarbonate copolymer resin A, in the compound represented by the general structural formula (1), a binder resin composed of compounds represented by the structural formula (1-a) to the structural formula (1-c) is particularly suitable. Met.
Specific examples are shown below, but are not limited thereto.

On the other hand, in the electrophotographic photoreceptor of the present invention, the polycarbonate copolymer resin A described above in the photosensitive layer can be further copolymerized with a polycarbonate containing siloxane.
Specifically, a polycarbonate resin containing siloxane represented by the general structural formula (5) or the general structural formula (10) is used.

In general structural formula 5, each of R _{10 and} R ₁₁ is independently a hydrogen atom, a halogen atom, a trifluoromethyl group, an alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms. Represents an alkyl group, an alkoxy group having 1 to 12 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 12 carbon atoms, a is an integer of 1 to 200, and X ₁ is —O -, Or the following general structural formula (6) or (7) (R ₁₃ in the structural formula is a hydrogen atom, a halogen atom, a trifluoromethyl group, an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 6 to 12 carbon atoms. It represents any of a substituted or unsubstituted aryl group, an alkoxy group having 1 to 12 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 12 carbon atoms, and b and b ′ are each independently An integer of 0-6, d is an integer of 0-4 .) Represents a group represented by, _{X 2} is -O-, or the following general formula (8) or (9) (in the structural _{formula, R 14} represents a hydrogen atom, a halogen atom, a trifluoromethyl group, a carbon An alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 12 carbon atoms And f and f ′ each independently represents an integer of 0 to 6, and l represents an integer of 0 to 4.

In General Structural Formula 10, R _{21 to} R ₃₂ each independently represent either an alkyl group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms, and m to p are each independently The integer of 2-6 is represented, q represents the integer of 0-200.
In the case where the photosensitive layer comprises a charge generation layer and a charge transfer layer, the resin can be applied to either layer.
The amount of the binder resin when used in the charge generation layer is 10 to 500 parts by weight, preferably 25 to 300 parts by weight, per 100 parts by weight of the charge generation agent.

  Next, the electrophotographic photoreceptor of the present invention contains a compound represented by the general structural formula (4) as a charge transfer agent.

In the general structural formula 4, R _{3 to} R ₅ are each independently hydrogen, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, an alkoxy group, substituted or unsubstituted carbon atoms having 6 to 12 carbon atoms. Represents a substituted aryl group.
The above charge transfer agent has good compatibility with the binder resin of the present invention and can provide an electrophotographic photosensitive member having high environmental resistance.
Among the compounds represented by the general structural formula (4), the compounds represented by the structural formulas (4-a) to (4-d) are particularly preferable because they have good compatibility with the binder resin of the present invention.
Specific compounds will be shown below, but are not limited thereto.

In the present invention, the ratio of the binder resin to the charge transfer agent is preferably in the range of 1.25 to 2.5 (weight ratio). More preferably, it is 1.5 to 2.0 (weight ratio). If it is more than 2.5 (weight ratio), the electrical characteristics deteriorate, for example, the residual potential increases. On the other hand, when it is less than 1.25 (weight ratio), mechanical properties such as wear resistance are deteriorated.
Furthermore, the compound represented by the general structural formula (4) and other charge transfer agents can be mixed and used. In this case, the content ratio of the compound of the general structural formula (4) and the other compound is as follows: compound of the general structural formula (4): other compound = 50: 50 to 95: 5, preferably 70:30 to 95: 5 The range is good.

Other charge transfer agents include polyvinyl carbazole, halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl pyrazoline, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, poly Conductive polymer compounds such as isothianaphthene, polyaniline, polydiacetylene, polyheptadiene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrocenylene, polyperinaphthylene, and polyphthalocyanine can be used.
Further, as a low molecular compound, trinitrofluorenone, tetracyanoethylene, tetracyanoquinodimethane, quinone, diphenoquinone, naphthoquinone, anthraquinone and derivatives thereof, polycyclic aromatic compounds such as anthracene, pyrene, phenanthrene, indole, carbazole, Nitrogen-containing heterocyclic compounds such as imidazole, fluorenone, fluorene, oxadiazole, oxazole, pyrazoline, hydrazone, triphenylmethane, triphenylamine, enamine, stilbene and the like can be used. Further, a polymer solid electrolyte in which a polymer compound such as polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylic acid or the like is doped with a metal ion such as Li ion can also be used.
Furthermore, an organic charge transfer complex formed of an electron donating compound typified by tetrathiafulvalene-tetracyanoquinodimethane and an electron accepting compound, etc. can be used. Desired photoreceptor characteristics can be obtained by mixing and adding the above compounds.
As a coating method of the coating solution, methods such as dip coating, spray coating, ring coating, bar coating spinner coating and the like can be used.

As the solvent for producing the electrophotographic photosensitive member of the present invention, tetrahydrofuran is suitable from the viewpoints of solubility of the binder resin and charge transfer agent, stability of the produced solution, and environmental load.
Antioxidants, ultraviolet absorbers, radical scavengers, softeners, curing agents, crosslinking agents, and the like are added to the coating solution for producing the electrophotographic photoreceptor of the present invention, so that the characteristics and durability of the photoreceptor are increased. The mechanical characteristics can be improved. In particular, the combined use of an antioxidant and an ultraviolet absorber contributes to improving the durability of the photoreceptor and is useful.
Among them, amine-based antioxidants are preferable for the photosensitive layer, and examples thereof include N-phenyl-1-naphthylamine, N-phenyl-N′-isopropyl-p-phenylenediamine, N, N-diethyl-p-phenylenediamine, N -Phenyl-N'-ethyl-2-methyl-p-phenylenediamine, N-ethyl-N-hydroxyethyl-p-phenylenediamine, alkylated diphenylamine, N, N'-diphenyl-p-phenylenediamine, N, N '-Diallyl-p-phenylenediamine, N-phenyl-1,3-dimethylbutyl-p-phenylenediamine, 4,4'-dioctyl-diphenylamine, 4,4'-dioctyl-diphenylamine, 6-ethoxy-2,2 , 4-Trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1, - it can be exemplified dihydroquinoline, N- phenyl -β- naphthylamine, N, a N'- di-2-naphthyl -p- phenylenediamine.

  The phenolic antioxidant is 2.6-di-tert-butylphenol, 2.6-di-tert-4-methoxyphenol, 2-tert-butyl-4-methoxyphenol, 2.4-dimethyl-6-tert. -Butylphenol, 2.6-di-tert-butyl-4-methylphenol, butylated hydroxyanisole, stearyl-propionate-β- (3.5-di-tert-butyl-4-hydroxyphenyl), α-tocopherol, monophenols such as β-tocopherol, n-octadecyl-3- (3′-5′-di-tert-butyl-4′-hydroxyphenyl) propionate, 2.2′-methylenebis (6-tert-butyl-4) -Methylphenol), 4.4'-butylidene-bis- (3-methyl-6-tert-butylpheno) ), 4.4′-thiobis (6-tert-butyl-3-methylphenol), 1.1.3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1.3 .5-trimethyl-2.4.6-tris (3.5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3 (3.5-di-tert-butyl-4-hydroxyphenyl) ) Propionate] Polyphenols such as methane are preferred, and one or more of them can be simultaneously contained in the photosensitive layer.

  Ultraviolet absorbers include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3.5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3.5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3.5 -Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3.5-di-tert-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5 ' -Tert-octylphenyl) benzotriazoles such as benzotriazole, phenyl salicylate, salicylic acid-p-ter - butylphenyl, salicylic acid are preferred, such as salicylate -p- octylphenyl, especially benzotriazole ultraviolet absorbers are preferred. One or more of the above antioxidants can be simultaneously contained in the photosensitive layer.

The addition amount of the phenolic antioxidant added to the electrophotographic photoreceptor of the present invention is 3 to 20% by weight with respect to the binder resin, and the addition amount of the amine antioxidant is 3 with respect to the binder resin. It is preferably in the range of ˜20% by weight. On the other hand, the addition amount of the ultraviolet absorber is preferably 3 to 30% by weight with respect to the binder resin.
In addition, a thin film made of an organic thin film such as polyvinyl formal resin, polycarbonate resin, fluororesin, polyurethane resin, or silicone resin, or a siloxane structure formed from a hydrolyzate of a silane coupling agent is formed on the photosensitive layer. A surface protective layer may be provided as a film. In that case, the durability of the photoreceptor is improved, which is preferable. This surface protective layer may be provided in order to improve functions other than the durability improvement.
The thickness of the protective layer is suitably from 0.1 to 20 μm.

The electrophotographic photosensitive member of the present invention, the universal hardness of the photosensitive layer surface, 185 N / mm ² or more 220 N / mm ² or less, the elastic work rate is 50% or less than 40%.
Universal hardness toner filming occurs at 185 N / mm ² or less, the 220 N / mm ² or more non-uniform image due to fine scratches on the surface of the photoreceptor occurs.
In the present invention, the universal hardness and the elastic power are Fischer Instruments H-100 (manufactured by Fischer Instruments), Vickers indenter, set load 9.8 mN, indentation depth 1 μm, measurement environment temperature 22 ° C., relative Measurement was performed under the condition of 55% humidity. For universal hardness, the displacement of the indenter at the maximum load was expressed as the hardness value, and the elastic power was calculated from the graph of load-unload test.

[toner]
The preferable toner in the present invention is preferably 3 to 10 μm in volume average particle diameter in consideration of the influence on the image quality, and more preferably 6 to 10 μm from the viewpoint of sufficiently exerting the cleaning property.
Further, when the toner image formed on the transfer paper is fixed, a release component is included in the toner base material in order to maintain and improve the separation performance between the paper and the fixing device.
The toner particles constituting the full-color image forming toner of the present invention include a first binder resin, a second binder resin, a colorant, a charge control agent, an outer layer, and a hydrocarbon wax, which will be described in detail later. It is preferable to use an additive.

[Binder resin]
The types of the first binder resin and the second binder resin are not particularly limited, and are known binder resins in the field of full color toners, for example, polyester resins, (meth) acrylic resins, styrene- (meth) acrylic copolymer resins. The resin may be a coalesced resin, epoxy resin, COC (cyclic olefin resin (for example, TOPAS-COC (manufactured by Ticona))), etc., but from the viewpoint of oilless fixing, the first binder resin and the second binder resin are either It is preferable to use a polyester resin.
As the polyester resin preferably used in the present invention, a polyester resin obtained by polycondensation of a polyhydric alcohol component and a polyvalent carboxylic acid component can be used. Among the polyhydric alcohol components, examples of the dihydric alcohol component include polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2- Bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane Bisphenol A alkylene oxide adducts such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanedio , 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A, and the like. Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol. 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, etc. Is mentioned.

Among the polyvalent carboxylic acid components, examples of the divalent carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and succinic acid. , Adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, n-octenyl succinic acid, isooctenyl succinic acid, n-octyl succinic acid , Isooctyl succinic acid, anhydrides or lower alkyl esters of these acids.
Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2 , 4-Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-
Methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empole trimer acid, anhydrides of these acids And lower alkyl esters.

In the present invention, as a polyester resin, a polyester resin raw material monomer, a vinyl resin raw material monomer, and a mixture of monomers that react with both resin raw material monomers are used to obtain a polyester resin in the same container. A resin obtained by performing a condensation polymerization reaction and a radical polymerization reaction for obtaining a vinyl resin in parallel (hereinafter, simply referred to as “vinyl polyester resin”) can also be suitably used. In addition, the monomer which reacts with the raw material monomers of both resins is, in other words, a monomer that can be used for both the condensation polymerization reaction and the radical polymerization reaction. That is, it is a monomer having a carboxy group that can undergo a condensation polymerization reaction and a vinyl group that can undergo a radical polymerization reaction, and examples thereof include fumaric acid, maleic acid, acrylic acid, and methacrylic acid.
Examples of the raw material monomer for the polyester resin include the polyhydric alcohol component and the polyvalent carboxylic acid component described above. Examples of the raw material monomer for the vinyl resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert- Butyl styrene,
Styrene or styrene derivatives such as p-chlorostyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; methyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, t-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, neopentyl methacrylate, 3- (methyl) butyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate Methacrylic acid alkyl esters such as dodecyl methacrylate; methyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, T-Butyl acrylate, n-pentyl acrylate, isopentyl acrylate, neopentyl acrylate, 3- (methyl) butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, acrylic Acrylic acid alkyl esters such as dodecyl acid; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid; acrylonitrile, maleic acid ester, itaconic acid ester, vinyl chloride, vinyl acetate, vinyl benzoate, vinyl methyl ethyl ketone Vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether. As a polymerization initiator when polymerizing the raw material monomer of the vinyl resin, for example, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1 Azo or diazo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, benzoyl peroxide, dicumyl peroxide, And peroxide polymerization initiators such as methyl ethyl ketone peroxide, isopropyl peroxycarbonate, lauroyl peroxide, and the like.

As the first binder resin and the second binder resin, various polyester resins as described above are preferably used. Among them, from the viewpoint of further improving the separability and offset resistance as an oilless fixing toner, More preferably, the first binder resin and the second binder resin shown are used.
A more preferred first binder resin is a polyester resin obtained by polycondensation of the above-mentioned polyhydric alcohol component and polyhydric carboxylic acid component, in particular, a bisphenol A alkylene oxide adduct as the polyhydric alcohol component. It is a polyester resin obtained using terephthalic acid and fumaric acid as components.
More preferred second binder resins are vinyl polyester resins, in particular, bisphenol A alkylene oxide adduct, terephthalic acid, trimellitic acid and succinic acid are used as raw material monomers for polyester resins, and styrene and butyl acrylate are used as raw material monomers for vinyl resins. It is a vinyl polyester resin obtained by using fumaric acid as a both-reactive monomer.

In the present invention, as described above, a hydrocarbon wax is internally added during the synthesis of the first binder resin. In order to add the hydrocarbon wax to the first binder resin in advance, when the first binder resin is synthesized, the hydrocarbon wax is added to the monomer for synthesizing the first binder resin. What is necessary is just to synthesize | combine binder resin.
For example, the polycondensation reaction may be performed in a state where a hydrocarbon wax is added to an acid monomer and an alcohol monomer constituting the polyester resin as the first binder resin. When the first binder resin is a vinyl-based polyester resin, the vinyl-based resin raw material monomer is added dropwise to the polyester resin raw-material monomer while stirring and heating the monomer while the hydrocarbon-based wax is added. The polycondensation reaction and the radical polymerization reaction may be performed.

[wax]
Generally, the lower the polarity of the wax, the better the releasability from the fixing member roller. The wax used in the present invention is a hydrocarbon wax having a low polarity.
The hydrocarbon wax is a wax composed of only carbon atoms and hydrogen atoms, and does not contain an ester group, an alcohol group, an amide group, or the like. Specific hydrocarbon waxes include polyolefin waxes such as polyethylene, polypropylene, copolymers of ethylene and propylene, petroleum waxes such as paraffin wax and microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax. . Among these, polyethylene wax, paraffin wax, and Fischer-Tropsch wax are preferable in the present invention, and polyethylene wax and paraffin wax are more preferable.

[Wax dispersant]
The toner of the present invention may contain a wax dispersant that helps to disperse the wax.
The wax dispersant is not particularly limited, and a known one can be used. A polymer, oligomer, or wax in which a unit having high compatibility with the wax and a unit having high compatibility with the resin exist as a block body. Polymer or oligomer in which one of highly compatible units and resin is highly grafted on the other, unsaturated hydrocarbon such as ethylene, propylene, butene, styrene, α-styrene, acrylic acid, Copolymers of α, β-unsaturated carboxylic acids such as methacrylic acid, maleic acid, maleic anhydride, itaconic acid and itaconic anhydride, their esters or anhydrides, vinyl resin and polyester blocks or grafts Examples include the body.
As the unit having high compatibility with the above wax, there are a long chain alkyl group having 12 or more carbon atoms, polyethylene, polypropylene, polybutene, polybutadiene and a copolymer thereof, and a unit having high compatibility with the resin. Examples thereof include polyester and vinyl resin.

[Charge control agent]
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts.
Of these, substances that control the negative polarity of the toner are particularly preferably used.

The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Usually, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.
The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. May be invited.

[Colorant]
A known colorant can be used for the toner of the present invention. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL , Isoindolinone yellow, bengara, red lead, red lead, cadmium red, cadmium mercury red, antimony red, permanent red 4R, para red, phise red, parachlor ortho nitroaniline red, risor fast scarlet G, Reliant Fast Scarlet, Brilliant Carmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermilion, benzidine Range, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo , Ultramarine, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridiane, emerald green, pigment green B, naphthol green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, Oxidized Chi Tan, zinc white, litbon and mixtures thereof can be used.
In the present invention, the content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

[Color batch masterbatch]
The colorant used in the present invention can also be used as a master batch combined with a resin. In addition to the polyester and vinyl resins mentioned above, binder resins that are kneaded with the masterbatch production or masterbatch include rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic A group petroleum resin, chlorinated paraffin, paraffin wax and the like can be mentioned, and these can be used alone or in combination.

[External additive]
In the present invention, one or more inorganic fine particles are preferably used as an external additive for assisting the fluidity and chargeability / developability / transferability of toner particles. The specific surface area of the inorganic fine particles by BET method is preferably 30 m2 / g to 300 m2 / g, and the primary particle diameter is preferably 10 nm to 50 nm. If the primary particle size is too large, it is difficult to fix the toner to the toner base, and the adverse effect on the image due to the removal of the external additive becomes remarkable. On the other hand, if the thickness is 10 nm or less, the durability is not sufficient because the material is heavily buried in the matrix.

Specific examples of the inorganic fine particles include, for example, silicon oxide, zinc oxide, tin oxide, silica sand, titanium oxide, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide. , Aluminum oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like. The total amount of the external additive in the present invention is preferably 1.0 to 4.0 parts by weight with respect to the toner base.
When the total amount of the external additive is larger than the above range, fogging, developability and fixing separation properties are deteriorated. When the total amount of external additives is less than the above range, fluidity, transferability, and heat-resistant storage properties are deteriorated.

[Adhesive strength of external additives]
After 2 g of toner was added to 30 cc of a surfactant solution diluted 10 times and sufficiently blended, energy was applied at 40 W for 1 minute using an ultrasonic homogenizer to separate, wash, and dry the toner, It is obtained by calculating the ratio of the adhesion amount of inorganic particles before and after treatment using a fluorescent X-ray analyzer.
The fluorescent X-ray analysis was performed by applying a force of 1 N / cm ² for 60 seconds to ² g each of the dry toner obtained by the above treatment and the pre-treatment toner using a wavelength dispersion type fluorescent X-ray analyzer XRF1700 manufactured by Shimadzu Corporation. Pellets were prepared and the elements unique to the inorganic fine particles (for example, silicon in the case of silica) were quantified by a calibration curve method.
As a result, it was found that the preferable adhesion strength of the external additive to the toner base is 45 to 65%. If the adhesion strength is 45% or less, the external additive fixed on the toner base is small, so the presence ratio of the free external additive is large, and the free external additive easily adheres to the photoreceptor, causing filming. Cheap. If it is 65% or more, the toner is excessively buried in the toner base and the fluidity is adversely affected.

[Cohesion]
In the toner of the present invention, the degree of aggregation of the toner is preferably 5 to 70 (%), more preferably 15 to 40 (%). When the cohesion value is lower than 5 (%), the toner is likely to scatter from the developing roller or background stains are likely to occur on the image.
On the other hand, when the ratio is higher than 70 (%), the aggregation between the toners becomes too large, causing a decrease in fluidity, and the toner on the photoreceptor is aggregated and solidified, resulting in filming around the cleaning blade.
The aggregation degree is measured as follows. The measuring device uses a powder tester manufactured by Hosokawa Micron (manufactured), and the attached parts are set on the shaking table in the following procedure.
(B) Vibro chute (b) Packing (c) Space ring (d) Flui (3 types) Top>Medium> Bottom (e) Osaba

Next, it fixes with a knob nut and operates a vibration stand. The measurement conditions are as follows.
Flute opening (top) 75μm
中 (Medium) 45μm
〃 (Bottom) 22μm
Swing scale 1mm
Sampling amount 2g
Vibration time 15 seconds After measurement, the degree of aggregation is obtained from the following calculation.
% By weight of powder remaining on the upper screen × 1 (a)
Weight% of powder remaining on middle stage sieve x 0.6 (b)
% By weight of powder remaining on the lower sieve x 0.2 (c)
The total of the above three calculated values is used as the degree of aggregation (%).
That is, the aggregation value (%) = (a) + (b) + (c).

[Adhesion between toners]
This is a value indicating the adhesion between toner particles obtained by measuring with a powder layer compression / tensile property measuring device (for example, “Ag Robot” (manufactured by Hosokawa Micron)). Specifically, it refers to the force required when the upper cell is lifted by filling 7.0 g of toner in a 25φ cell that can be divided into two vertically and applying a weight of 8 kg for 5 minutes. The temperature control system attached to this device was used for the ambient temperature.
It is desirable that the adhesive force between toners has a small temperature change. If the adhesion force between the toners is large, the particle behavior in the part where the stress is applied in the actual machine is not stable. In particular, the adhesion force between the toners in an atmosphere of 25 ° C. is preferably 45 g or more from the lower limit of oilless grinding, and 55 g or less is preferred because movement from a stationary state becomes worse. In particular, in the cleaning blade nip portion, the stress is large and causes filming.

Examples of the present invention will be described below.
Example 1
[Production of toner]
Polyester resin A (softening point 131 ° C, AV value 25) ··· 68 parts polyester resin B (softening point 116 ° C, AV value 1.9) · · 32 parts cyan master batch (Pigment Blue 15: 3 50 parts) ) ・ ・ 8 parts Carnauba wax ・ ・ 8 parts After thoroughly mixing the above toner materials with a Henschel mixer, use the one from which the discharge part of the twin-screw extrusion kneader (PCM-30: manufactured by Ikekai Tekko Co., Ltd.) has been removed. The resulting mixture was rolled to a thickness of 2 mm with a cooling press roller, cooled with a cooling belt, and coarsely pulverized with a feather mill. Then, after pulverizing with a mechanical pulverizer (KTM: Kawasaki Heavy Industries, Ltd.) to an average particle size of 10-12 μm, and further pulverizing with a jet pulverizer (IDS: Nippon Pneumatic Industrial Co., Ltd.), Fine powder classification was performed using a rotor type classifier (Teplex type classifier type 100ATP: manufactured by Hosokawa Micron Corporation) to obtain a toner base A having a volume average particle diameter of 7.9 μm and an average circularity of 0.910. To 100 parts of this toner base A, 2 parts of silica (RX200) was added and mixed with a Henschel mixer at a peripheral speed of 40 m / sec for 5 minutes to prepare a toner.

[Production of photoconductor]
Alkyd resin (Beckolite M-6401-50 manufactured by Dainippon Ink and Chemicals) and amino resin (Super Becamine G-821-60 manufactured by Dainippon Ink and Chemicals, Inc.) on a cylindrical drum made of uncut aluminum with a diameter of 30 mm ) In a ratio of 65:35, and the mixed resin and titanium oxide (CR-EL Ishihara Sangyo Co., Ltd.) in a ratio of 1: 3 are dissolved in methyl ethyl ketone to form a coating solution having a thickness of 1.5 μm. Formed with.
Next, 10 g of Y-type oxytitanium phthalocyanine powder having a maximum peak at an X-ray diffraction angle Cukα (2θ ± 0.2 degrees) of 27.2 degrees in FIG. 5 was added to glass beads and 500 ml of 1,3 dioxolane with a polyvinyl butyral resin ( (BX-1 Sekisui Chemical Co., Ltd.) 10 g dissolved liquid was added, and the mixture was dispersed with a sand mill disperser for 20 hours. The resulting dispersion was filtered to remove the glass beads, and a charge generation layer coating solution was prepared. . This was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.2 μm. Next, as the binder resin, a polycarbonate copolymer resin A having a structural formula (1-a) and a structural formula (2) in a molar ratio (mol) of 40:60 and a viscosity average molecular weight (Mv: 30,000). And a polycarbonate resin B having a viscosity average molecular weight (Mv: 80,000) represented by the structural formula (3), and the weight ratio is 50:50.
The charge transfer agent is a compound represented by the structural formula (4-a). The weight ratio of the binder resin to the charge transfer agent is 100: 60. The binder resin and the charge transfer agent were dissolved in tetrahydrofuran to prepare a charge transfer layer coating solution. The substrate on which the charge generation layer was formed was dip-coated in the charge transfer layer coating solution and dried at 130 ° C. for 60 minutes to form a charge transfer layer having a thickness of 24.0 μm. Thus, an electrophotographic photosensitive member was produced.

The printing apparatus of the cleaning device described in this embodiment, the toner adjusted as described above, and the photoconductor is subjected to a printing durability test for 5000 sheets in a high temperature environment (32 ° C./54% Rh), and scratches and filming on the photoconductor are generated. The situation was confirmed.
The results are shown in Table 1 (Examples) and Table 2 (Comparative Examples).
The evaluation machine was a modified version of RICOH CX3000, and the photoconductor, cleaning blade, and toner were replaced with standard products, and experiments were conducted. The charging condition is a contact charging method using a charging roll, and a voltage is applied so that the surface potential of the photoreceptor can be uniformly charged to -500 V. The developing condition is a developing method using a contact roll, and an intermediate transfer belt is used. You are using a device.
The system speed was 120 mm / sec, and the cleaning blade (elastic blade) was a urethane rubber blade having a hardness of 70 °, a rebound resilience of 40%, a thickness of 1.8 mm, and a free length of 8 mm.

<Image density> Evaluation was made according to the following criteria.
Good: Poor density <Filming> Filming on the photoreceptor after running 5000 sheets was evaluated according to the following criteria.
◎: Good ○: There is a cleaning defect but there is no effect on the image quality △: Minor image defect ×: Extremely poor <Scratch>
In the same manner as described above, the presence or absence of scratches on the photoconductor was judged according to the following criteria.
◎: Good ○: Slight scratch (no image effect)
×: Extremely bad

(Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the structural formula (1-a) of the polycarbonate copolymer resin A used in Example 1 was replaced with the structural formula (1-b).
(Example 3)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the structural formula (1-a) of the polycarbonate copolymer resin A used in Example 1 was replaced with the structural formula (1-c).
Example 4
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the molar ratio of Structural Formula (1) and Structural Formula (2) of the polycarbonate copolymer resin A used in Example 1 was 30:70. .
(Example 5)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the weight ratio of the polycarbonate copolymer resin A and the polycarbonate resin B used in Example 1 was changed to 70:30.
(Example 6)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the weight ratio of the polycarbonate copolymer resin A and the polycarbonate resin B used in Example 1 was changed to 30:70.

(Example 7)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent (Structural Formula 4-b).
(Example 8)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent (Structural Formula 4-c).
Example 9
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the charge transfer agent used in Example 1 was replaced with the charge transfer agent (Structural Formula 4-d).
(Example 10)
In addition to the binder resin and charge transfer agent used in Example 1, 2.6-di-tert-butylphenol and N-phenyl-1-naphthylamine as the antioxidants were absorbed by 5% of the charge transfer agent, respectively, and absorbed by ultraviolet rays. An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 5% of the agent 2- (5-methyl-2-hydroxyphenyl) benzotriazole was added to the charge transfer agent.
(Example 11)
A toner was prepared in the same manner as in Example 1 except that the toner used in Example 1 was changed to 4 parts of the wax component.
Example 12
A toner was prepared in the same manner as in Example 1 except that the silica component in the toner used in Example 1 was changed to 3.5 parts.
(Example 13)
A toner was prepared in the same manner as in Example 1 except that the mixing time in the Henschel mixer was set to 8 minutes.
(Example 14)
For Example 1, the experiment was performed in the same manner as in Example 1 except that the mixing ratio of the rubber material of the cleaning blade was changed to a hardness of 75 °.
(Example 15)
For Example 1, the experiment was performed in the same manner as in Example 1 except that the mixing ratio of the rubber material of the cleaning blade was changed and the rebound resilience was 50%.

(Comparative Example 1)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the structural formula (2) of the polycarbonate copolymer resin A used in Example 1 was replaced with the structural formula (11).

(Comparative Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 8 except that the weight ratio of the polycarbonate copolymer resin A and the polycarbonate resin B used in Example 1 was changed to 80:20.
(Comparative Example 3)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the weight ratio of the polycarbonate copolymer resin A and the polycarbonate resin B used in Example 1 was changed to 20:80.
(Comparative Example 4)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transfer agent (Structural Formula 12) was used instead of the charge transfer agent used in Example 1.

(Comparative Example 5)
Except that the Y-type oxytitanyl phthalocyanine of the charge generating agent used in Example 1 was replaced with the α-type oxytitanyl phthalocyanine having the X-ray diffraction angle Cukα (2θ ± 0.2 degrees) of FIG. An electrophotographic photoreceptor was prepared in the same manner as in Example 1.
(Comparative Example 6)
A toner was prepared in the same manner as in Example 1 except that 10 parts of the wax component was used in the toner used in Example 1.
(Comparative Example 7)
A toner was prepared in the same manner as in Example 1 except that 1 part of the wax component was used in the toner used in Example 1.
(Comparative Example 8)
A toner was prepared in the same manner as in Example 1 except that the silica component in the toner used in Example 1 was changed to 5.5 parts.
(Comparative Example 9)
A toner was prepared in the same manner as in Example 1 except that the silica component in the toner used in Example 1 was changed to 0 part.
(Comparative Example 10)
For Example 1, the experiment was performed in the same manner as in Example 1 except that the mixing ratio of the rubber material of the cleaning blade was changed to a hardness of 58 °.
(Comparative Example 11)
For Example 1, the experiment was performed in the same manner as in Example 1 except that the mixing ratio of the rubber material of the cleaning blade was changed to 80 °.
(Comparative Example 12)
For Example 1, the experiment was performed in the same manner as in Example 1 except that the mixing ratio of the rubber material of the cleaning blade was changed and the rebound resilience was 65%.

1 is a diagram illustrating a schematic configuration of a tandem type image forming apparatus according to an embodiment of the present invention. It is a schematic block diagram of a process cartridge. It is detail drawing of a cleaning apparatus. It is sectional drawing of the photosensitive layer of a photoconductor drum. It is a figure which shows the X-ray-diffraction angle characteristic of Y type- oxytitanium phthalocyanine. It is a figure which shows the X-ray-diffraction-angle characteristic of (alpha) -oxy titanyl phthalocyanine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum as an image carrier 2 Charging apparatus as charging means 4 Developing apparatus as transfer means Constructing intermediate transfer apparatus 5 Developer 6 Intermediate transfer belt as transfer target 7 Primary transfer roller as transfer means 15 Process cartridge

Claims (15)

A charging unit for uniformly charging the image carrier, an exposure unit for exposing the uniformly charged surface of the image carrier to form an electrostatic latent image, and the formed electrostatic latent image as a developer. Development means for forming a visible image on the image carrier, transfer means for transferring the image on the image carrier to a transfer target, and the developer remaining on the image carrier after the transfer is mainly elastic. In an image forming apparatus having a cleaning means for removing with a body blade,
As a developer, a non-magnetic one-component toner containing a wax component is used,
The image bearing member has a universal hardness of 185 to 220 N / m ² , an elastic deformation rate of 40 to 50%, and an adhesion strength of an external material in the developer of 45 to 65%. Image forming method. The image forming method according to claim 1.
The electrophotographic photosensitive member as the image bearing member includes a polycarbonate copolymer resin A containing at least repeating units represented by structural formulas (1) and (2) as a binder resin in the photosensitive layer, and a structural formula. An image forming method comprising: a polycarbonate resin B represented by (3), wherein the weight ratio of the polycarbonate copolymer resin A to the polycarbonate resin B is in the range of 30:70 to 70:30.

(In Structural Formula 1, R ₁ and R ₂ each independently represent a hydrogen atom, a halogen atom, or a substituted and unsubstituted alkyl group having 1 to 6 carbon atoms.)

The image forming method according to claim 2.
An image forming method, wherein the charge generating agent in the photosensitive layer is Y-type oxytitanium phthalocyanine. The image forming method according to claim 2 or 3,
The image forming method, wherein the charge transfer agent in the photosensitive layer is a distyryl charge transfer agent represented by the general structural formula (4).

(In Structural Formula 4, R _{3 to} R ₅ are each independently hydrogen, a halogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, an alkoxy group, substituted or unsubstituted carbon atoms having 6 to 12 carbon atoms Represents a substituted aryl group.) The image forming method according to claim 2,
The image forming method, wherein the photosensitive layer contains a phenolic antioxidant, an amine antioxidant, and a benzotriazole ultraviolet absorber as additives. The image forming method according to any one of claims 2 to 5,
An image forming method, wherein the photosensitive layer components are dissolved and tetrahydrofuran is used as a solvent for forming the photosensitive layer. The image forming method according to claim 1,
An image forming method, wherein the developer is pulverized toner. The image forming method according to claim 1,
The image forming method, wherein the developer contains 3 to 10% of a wax component. The image forming method according to claim 1,
The image forming method, wherein the developer contains 0.5 to 4.0% of an external component. The image forming method according to claim 1,
An image forming method, wherein the developer has an aggregation degree of 5 to 70%. The image forming method according to claim 1,
The image forming method, wherein the developer has an adhesion force between toners of 45 to 55 g. The image forming method according to claim 1,
The image forming method according to claim 1, wherein the elastic blade has a hardness specified by JIS-A of 60 to 80 °. The image forming method according to claim 1,
The image forming method according to claim 1, wherein the elastic blade has a rebound resilience of 35 to 55%.   14. A process cartridge integrally comprising the image carrier, the developer, and the cleaning means in the image forming method according to claim 1.   An image forming apparatus capable of performing the image forming method according to claim 1.

Images