JP5272776B2 - Protective agent for photoreceptor, protective layer forming apparatus, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective agent for a photoreceptor capable of protecting a photoreceptor, even when linear velocity of the photoreceptor is high, preventing black stripes from being caused due to an increase in resistance of a charging roller and enabling high-quality image formation, and to provide a protective layer forming device which uses the protective agent for the photoreceptor, an image forming apparatus, and a process cartridge. <P>SOLUTION: The protective agent for the photoreceptor includes a protective agent block containing a metallic soap, wherein a split face obtained by breaking the protective agent block is composed of flat fragments having 0.2 to 2 &mu;m thickness, the surface of the fragment having 0.2 to 2 &mu;m thickness is a homogenous plane, and it is desirable that the inside of the flat fragment be formed by fusing metallic soap particles having 0.05 to 0.2 &mu;m of average particle size. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a protective agent for a photosensitive member that protects the surface of the photosensitive member and is used for electrophotographic image formation, a protective layer forming apparatus that forms a protective layer made of the protective agent on the surface of the photosensitive member, and The present invention relates to an image forming apparatus and a process cartridge to be used.

In an image forming apparatus using an electrophotographic process, an image is formed by performing a charging process, an exposure process, a development process, and a transfer process on a photoreceptor. The discharge product generated in the charging process and remaining on the surface of the photoreceptor and the residual toner remaining on the surface of the photoreceptor after the transfer process are removed through a cleaning process.
As a cleaning method in the cleaning process, a rubber blade is used that is inexpensive, has a simple mechanism, and has excellent cleaning properties. However, since the rubber blade is pressed against the photoconductor to remove the residue on the surface of the photoconductor, mechanical stress due to friction between the surface of the photoconductor and the cleaning blade is large, resulting in wear of the rubber blade, especially in organic photoconductors. Wear of the photoreceptor surface layer occurs, shortening the life of the rubber blade and the organic photoreceptor. In addition, the toner used for image formation in response to the demand for higher image quality has become a small particle size. In such an image forming apparatus using a toner having a small particle size, the ratio of residual toner passing through the cleaning blade increases. In particular, the dimensional accuracy and assembly accuracy of the cleaning blade are not sufficient, or the cleaning blade is partially In the case of shaking, the toner slipped out and prevented high-quality image formation.
Therefore, in order to extend the life of the organic photoreceptor and maintain high image quality over a long period of time, it is necessary to reduce deterioration of the member due to friction and improve cleaning properties.

  In response to this requirement, for example, in Patent Document 1, a brush or the like is pressed against a metal soap block (protective agent block) such as zinc stearate and supplied to the photoreceptor, and a lubricant film is formed by a cleaning blade. A method has been proposed. In this proposal, by using a metal soap such as zinc stearate, the lubricity of the photoreceptor surface is improved, and friction between the photoreceptor and the cleaning blade can be reduced. It was very preferable because it also improved.

  In recent years, in the charging process, so-called AC charging using a charging roller or the like for charging by superimposing an AC voltage on a DC voltage has been used. This AC charging has excellent performance such as high uniformity of the charging potential of the photoconductor, less generation of oxidizing gas such as ozone and NOx, and miniaturization of the apparatus, but the applied AC voltage. Depending on the frequency, the positive and negative discharges of several hundred to several thousand times per second are repeated between the charging member and the photoconductor, so that the photoconductor is subjected to this large number of discharges and the deterioration of the surface layer is accelerated. For this deterioration, if a lubricant is applied to the photoconductor, the AC charging energy is first absorbed by the lubricant and the photoconductor is difficult to reach, so that the photoconductor is protected.

The metal soap is decomposed by the AC charging energy, but the metal soap is not completely decomposed and disappears, but a fatty acid having a low molecular weight is generated, and the frictional force between the photosensitive member and the cleaning blade is increased. In addition to the fatty acid, the toner component easily adheres in a film form on the photosensitivity, and the resolution of the image tends to be lowered. . For this reason, it is necessary to supply a large amount of metal soap onto the photoconductor so that the surface of the photoconductor can be immediately covered with metal soap even if fatty acids are generated. Furthermore, due to the demand for higher speed image formation, the linear velocity of the photosensitive member becomes faster, and accordingly, the amount of metal soap supplied to the photosensitive member needs to be increased.
Here, the metal soap block used in the image forming apparatus is generally manufactured by putting a melted metal soap in a mold and cooling (see Patent Document 2). The produced metal soap block has an isotropic crystal and is dense. Therefore, in order to increase the supply amount of the metal soap in an image forming apparatus using AC charging and a high linear velocity of the photoreceptor, the metal soap is used. Since the pressure of the brush pressed against the block is increased, the durability of the brush was not sufficient.

In general, simply supplying finely pulverized metal soap particles on the photoconductor does not uniformly coat the photoconductor, and it is necessary to spread the pulverized metal soap particles with a blade to form a film. is there.
For example, in Patent Document 3, the size of the metal soap particles supplied to the photoconductor is 1 μm or less, so that the metal soap is coated on the photoconductor to improve the cleaning property. However, when the linear velocity of the photoconductor is increased, if the metal soap particles supplied to the photoconductor are small, the metal soap particles pass through the blade along with the vibration when the photoconductor is driven, and the metal soap becomes a film-like shape. It has been found that regions that are not formed easily occur.
Further, in Patent Document 4, when the metal soap particles supplied to the photoreceptor are large, the metal soap reaches just below the charging roller, and the metal soap particles are electrostatically attached to the charging roller. The attached metal soap oxidizes and melts and adheres to the charging roller. When metal soap is fixed, the toner component existing on the photosensitive member is fixed so as to be involved, so that the resistance of the charging roller at that portion becomes high, charging failure occurs, and black stripes are generated. It is disclosed that there is. From these facts, it was believed that the metal soap particles supplied to the photoreceptor should be small.

  Moreover, the metal soap particles scraped by the brush become irregular and granular fine powder. The metal soap particles are squeezed with a blade while the linear velocity of the photoconductor is low, crushed and further pulverized and applied onto the photoconductor. When the linear velocity is increased, relatively large metal soap particles before being finely applied and applied to the photoreceptor pass through the blade and reach the charging roller, and the metal soap particles electrostatically adhere to the charging roller, and AC The charged metal soap is oxidized and melted by the energy of charging, and is fixed to the charging roller. When the metal soap is fixed, the toner component existing on the photoconductor is fixed so as to be involved, so that the resistance of the charging roller at that portion becomes high, charging failure occurs, and black stripes are generated. There was a bug.

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is, the present invention provides a protective agent for a photosensitive member that can protect the photosensitive member even when the photosensitive member linear speed is high, and that does not generate black streaks due to an increase in the resistance of the charging roller and can form a high-quality image. And a protective layer forming apparatus, an image forming apparatus, and a process cartridge using the protective agent for the photoreceptor.

In order to solve the above problems, the present inventors have been able to reliably apply the metal soap to the surface of the photoconductor even when the photoconductor linear speed is increased when the metal soap is used for the photoconductor. As a result of intensive investigations on the means to prevent flying to the charging roller without passing through the blade, it was considered effective to control the metal soap particles inside the metal soap block, and the metal produced under various manufacturing conditions The soap block was examined.
In general, as shown in FIGS. 1 and 2, the inside of the produced metal soap particle block is isotropic because it has a shape in which metal soap particles of about 0.1 μm are fused. For this reason, it is hard as a whole, and the metal soap fine particles are too small for the brush hair diameter (about 5 μm to 30 μm) as a commonly used protective agent supply means. Supplied to the photoreceptor. The supplied metal soap lump is crushed with a blade and applied to the photoconductor, but the metal soap lump is very hard and roughly spherical, so it is difficult to crush with the blade and is applied on the photoconductor. It has been found that black streaks are likely to occur due to the fact that they are difficult to occur and fly through the blade to the charging roller.
Furthermore, the present inventors have found that if the inside of the metal soap block is fine particles that are easily applied to the photoconductor with a blade, the metal soap fine particles are efficiently applied to the photoconductor even if the force of pressing the brush is weak. It was found that the metal soap supplied was crushed with a blade and could be applied onto the photoreceptor.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A protective agent for a photoconductor comprising a protective agent block containing a metal soap, wherein a split surface obtained by dividing the protective agent block is composed of a flat piece having a thickness of 0.2 μm to 2 μm. is there.
<2> The surface of a flat piece having a thickness of 0.2 μm to 2 μm is a homogeneous surface, and the inside of the flat piece is formed by fusing metal soap particles having an average particle size of 0.05 μm to 0.2 μm. The photoconductor protective agent according to <1>.
<3> The photoconductor protective agent according to any one of <1> to <2>, wherein the metal soap is a mixture of zinc stearate and zinc palmitate.
<4> The photoconductor protective agent according to any one of <1> to <3>, wherein the protective agent block contains boron nitride.
<5> Protective agent supplying means for supplying a photosensitive agent protective agent to the surface of the photosensitive member;
A pressing unit that presses the protective agent for a photoreceptor according to any one of <1> to <4> to the protective agent supply unit;
A protective layer forming apparatus comprising: a thinning means for thinning a layer made of the protective agent for the photoreceptor supplied to the surface of the photoreceptor by the protective agent supply means.
<6> The protective layer forming apparatus according to <5>, wherein the blade as the thinning unit is in contact with the photoconductor in the counter direction.
<7> A process cartridge comprising at least a photosensitive member and the protective layer forming unit according to any one of <5> to <6>, wherein the process cartridge is detachable from the main body of the image forming apparatus. is there.
<8> a photoconductor, an electrostatic latent image forming unit that forms an electrostatic latent image on the photoconductor, a developing unit that develops the electrostatic latent image with toner to form a visible image, Transfer means for transferring the visible image to a recording medium, protective layer forming means according to any one of <5> to <6>, and fixing means for fixing the transferred image transferred to the recording medium. An image forming apparatus including at least the image forming apparatus.

  According to the present invention, the conventional problems can be solved, and even when the photosensitive member linear velocity is high, the photosensitive member can be protected, and black streaks due to the increased resistance of the charging roller do not occur, and high-quality image formation is achieved. A protective layer forming apparatus capable of performing the above, and an image forming apparatus and a process cartridge using the protective layer forming apparatus can be provided.

FIG. 1 is an electron micrograph showing the internal state of the photoconductor protective agent. FIG. 2 is an electron micrograph showing the internal state of the photoconductor protective agent. FIG. 3 is an electron micrograph of a cross section when the photoconductor protective agent of the present invention is broken. FIG. 4 is an electron micrograph of a cross-section when the photoconductor protective agent of the present invention is broken. FIG. 5 is a schematic view showing an example of the protective layer forming apparatus of the present invention. FIG. 6 is a schematic view showing another example of the protective layer forming apparatus of the present invention. FIG. 7 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 8 is a schematic view showing an example of the process cartridge of the present invention. FIG. 9 is a diagram for explaining how to divide the protective agent block.

(Protective agent for photoconductor)
The photoconductor protective agent of the present invention comprises a protective agent block containing a metal soap, and the split surface obtained by dividing the protective agent block is composed of flat pieces having a thickness of 0.2 μm to 2 μm.

  Here, FIG. 3 and FIG. 4 show an example of a split surface obtained by breaking the protective agent block. The split surface of the protective agent block is composed of flat pieces, and the thickness thereof is 0.2 μm to 2.0 μm, preferably 0.4 μm to 1.8 μm, more preferably 0.6 μm to 1.6 μm. preferable. If the thickness is less than 0.2 μm, it is difficult to produce substantially, and even if it can be produced, the fine particles of about 0.1 μm have the same function as a conventional protective agent block having a fused shape. It is not preferable because it does not have. On the other hand, when the thickness exceeds 2.0 μm, the shape of the protective agent block tends to be bent, and voids are generated inside the protective agent block, which may become brittle.

The flat piece of 0.2 μm to 2.0 μm in thickness present in the cross section of the protective agent block has a homogeneous surface, but the inside of the flat piece is formed by fusing metal soap particles. It is preferable. The average particle diameter of the metal soap particles inside the flat piece is preferably 0.05 μm to 0.2 μm, more preferably 0.06 μm to 0.18 μm, and still more preferably 0.08 μm to 0.16 μm.
Here, the average particle diameter of the metal soap particles includes, for example, a method of measuring each particle by observation with an optical microscope or an electron microscope, or measurement using a Coulter counter.
Since the inside of the flat piece has such a shape, when the protective agent is pulverized by pressing the brush, it becomes easy to be supplied to the photoconductor so that this piece is peeled off. The surface of the photoreceptor can be coated while being crushed.

  When a brush is pressed against the protective agent block, the flat piece or a lump containing a plurality of flat pieces is supplied to the photoreceptor. Even a lump containing a plurality of flat pieces is immediately divided into flat pieces by a blade. The flat piece is gradually stretched by the blade while staying in the vicinity of the blade to cover the photoconductor. Further, since the flat piece stays in the vicinity of the blade, it hardly passes through the blade and flies to the charging roller. Of course, the pressure of the brush pressed against the protective agent block can be supplied to the photoconductor even if the pressure of the brush is weaker than that of the conventional protective agent block.

The fact that the split surface of the protective agent block is composed of the above-described flat pieces utilizes the volume shrinkage when the metal soap is melted and cooled. The protective agent block can be produced by holding the melted metal soap at a temperature near the freezing point and then rapidly cooling it. When the molten metal soap is maintained at a temperature near the freezing point during the production of the protective agent block, it is preferable to apply ultrasonic waves to the molten metal soap so that it is close to supercooling. By doing so, the protective agent block starts to solidify from the whole, and the protective agent block having the internal structure as in the present invention is manufactured.
When the protective agent block is made, simply by rapidly cooling the molten metal soap, the protective agent block solidifies from the outside at a low temperature, so that the shape of the entire protective agent block is bent or a large gap is formed inside. This is not preferable. Moreover, when the molten metal soap is gradually cooled, a protective agent block having a shape in which conventionally used fine particles of about 0.1 μm are fused is produced.

The method of dividing the protective block is not particularly limited and may be appropriately selected depending on the purpose. For example, (1) cutting with a knife, saw, heating wire, etc., (2) bruise with a hammer, etc. (3) A method of providing a fulcrum below the protective agent block and applying a force downward at two points away from the fulcrum, (4) a method of holding the protective agent block at two locations, and moving the two locations in different directions, etc. It is done. However, the cutting of (1) and the bruise of (2) are not so preferable because the cross section is formed with the fractured face broken, and the methods (3) and (4) are particularly preferable. . Since the area to be observed by the split surface should be about 1 mm ² , when the protective agent block is split, if the scratch is provided at the place where the protective agent block is to be cracked, the split surface can be observed well. become able to.

  The metal soap used for the protective agent block is not particularly limited and may be appropriately selected depending on the intended purpose. For example, laurate, myristic acid, palmitate, stearate, behenate, lignocerate , Having an anion (anion) at the end of the hydrophobic site, such as a long-chain alkyl carboxylate such as serotenate, montanate, melicinate, etc., and alkali metal ions such as sodium and potassium, Examples thereof include compounds in which alkaline earth metal ions such as magnesium and calcium and metal ions such as aluminum and zinc are bonded. Specific examples include zinc stearate, calcium stearate, magnesium stearate, zinc laurate, calcium laurate, magnesium laurate, and zinc palmitate. These may be used individually by 1 type and may use 2 or more types together. Among these, zinc stearate, zinc palmitate and a mixture of zinc stearate and zinc palmitate, which have good film forming properties and a high protective effect, are preferred, and a mixture of zinc stearate and zinc palmitate is particularly preferred.

  Both the zinc stearate and zinc palmitate are fatty acid metal salts, but the fatty acid portion has stearic acid having 18 carbon atoms and palmitic acid having 16 carbon atoms. Therefore, zinc stearate and zinc palmitate are similar in structure and are compatible with each other, and behave as almost the same material, both of which can protect the photoreceptor in the same way.

Since the zinc palmitate has a lower melting point than zinc stearate, if a certain amount or more is contained in zinc stearate, the protective agent is easily stretched by the blade, so even if the linear velocity of the photoreceptor is high. The protective agent can sufficiently coat the photoconductor.
In addition, as the linear velocity of the photoconductor increases, the charging energy falling on the photoconductor, particularly the AC charging energy, becomes stronger. Therefore, in order to enhance the protective effect of the photoconductor by the protective agent, the protective agent on the photoconductor It is necessary to increase the thickness.

  It is said that the zinc stearate does not adhere randomly on the photoreceptor, but is stable when attached with two molecules. That is, even if zinc stearate is applied on the photoreceptor, it is saturated at the thickness of two molecules of zinc stearate. Here, when zinc palmitate having a slightly smaller molecular length than zinc stearate is contained in a certain amount or more, the height of the molecular layer is not constant, and the low part and the high part coexist. Then, the next molecule enters the lower part and forms a molecular layer. Therefore, as a result, a protective agent layer thicker than two molecules can be formed, and the protective effect of the photoreceptor is improved. Naturally, if the amount of zinc palmitate is excessively large, a bilayer of zinc palmitate tends to be formed, and the thickness of the protective agent does not increase. In addition, since the palmitate is smaller than the zinc stearate, the protective effect of the photoconductor is reduced as compared with the zinc stearate alone.

  When the mixture of zinc stearate and zinc palmitate is used for the protective agent of the present invention, each powder may be mixed and used, but since each powder particle has a certain size, Since a portion with a large amount of zinc stearate and a portion with a large amount of zinc palmitate are likely to be formed on the photoreceptor, it is preferable that zinc stearate and zinc palmitate are compatible in one particle. In one particle, zinc stearate and zinc palmitate are compatible with each other by melting and mixing the respective materials, cooling, pulverizing, and powder in which zinc stearate and zinc palmitate are compatible. Zinc stearate and zinc palmitate are mixed by a dry method or a wet method, which is a known method for producing metal soap, using a method of preparing a body or a mixture of stearic acid and palmitic acid in a predetermined amount as a raw material. A method of producing melted particles is used. In the production method using a mixture of stearic acid and palmitic acid in a predetermined amount, the mixing ratio of stearic acid and palmitic acid is almost the same as the mixing ratio of zinc stearate and zinc palmitate. It is particularly preferable because it is not only completely compatible with zinc palmitate but also has very high reproducibility and productivity.

  The ratio of zinc stearate and zinc palmitate in the protective agent block may be calculated by the amount of material input if the material to be used is definitely known, but the material always contains impurities. The ratio of zinc stearate and zinc palmitate in the produced protective agent block is preferably measured for each production lot. The ratio of zinc stearate and zinc palmitate in the protective agent block is determined by dissolving the protective agent block in hydrochloric acid-methanol solution and heating at 80 ° C. to methylate stearic acid and palmitic acid, and by gas chromatography, The ratio of stearic acid and palmitic acid can be determined accurately.

  The ratio (mass) of zinc stearate and zinc palmitate used in the protective agent block is preferably 75:25 to 40:60, more preferably 66:34 to 40:60, and further 65:45 to 45:55. preferable. When the ratio of the zinc stearate is more than 75% by mass, if the linear velocity of the photoconductor is increased, it may be difficult to apply the protective agent on the photoconductor. The body's protective effects may be reduced.

  In addition to zinc stearate and zinc palmitate, the photoconductor protective agent of the present invention may contain other different metal soaps. However, metal soaps that are structurally different from zinc stearate and zinc palmitate are not preferred because zinc stearate and zinc palmitate may disturb the protective layer formed on the photoconductor. Zinc stearate and palmitic acid are not preferred. A metal soap similar in structure to zinc (a fatty acid zinc soap having 13 to 20 carbon atoms) is preferred.

Moreover, it is preferable to add talc and boron nitride having self-lubricating properties to the photoconductor protective agent of the present invention in order to maintain the lubricity of the photoconductor. Among these, boron nitride is particularly preferable because it has a graphite structure, has high lubricity and is chemically stable.
The content of talc and / or boron nitride in the entire protective agent is preferably 1% by mass to 25% by mass, more preferably 2% by mass to 23% by mass, and still more preferably 3% by mass to 21% by mass. When the content of talc and / or boron nitride in the total amount of the protective agent for the photoreceptor is less than 1% by mass, the self-lubricating property of talc and / or boron nitride is not exhibited, and therefore the meaning of containing talc and / or boron nitride is included. Absent. If the content of talc and / or boron nitride in the total amount of the protective agent for the photoconductor is greater than 25% by mass, talc and / or boron nitride accumulates thickly on the photoconductor, thereby reducing the sensitivity of the photoconductor. It is not preferable.

  Further, the protective agent for a photoreceptor of the present invention includes inorganic fine particles such as silica, alumina, ceria, zirconia, clay, calcium carbonate, or surface hydrophobized fine particles; polymethyl methacrylate fine particles, polystyrene fine particles, silicone resin fine particles. Organic fine particles such as α-olefin-norbornene copolymer resin fine particles can also be added. These particles themselves do not have an effect of protecting the photoconductor, but have an effect of leveling the photoconductor protective agent that has adhered to the photoconductor too much. Among these, alumina is particularly preferable because it does not decrease the sensitivity of the photoreceptor even if it is deposited on the photoreceptor. When using alumina, the particle size is preferably 0.05 μm to 2 μm, more preferably 0.10 μm to 1 μm, and still more preferably 0.15 μm to 0.7 μm.

  In addition, an amphiphilic organic compound such as a surfactant is used in combination as an additive to increase the affinity between the protective agent for the photosensitive member and the surface of the photosensitive member, and to assist in the formation of the protective agent layer. Also good.

  The amphiphilic organic compound may greatly change the surface characteristics of the main material, so the amount added is 0.01% by mass to 3% by mass with respect to the total mass of the protective agent for the photoreceptor. Is preferable, and 0.05 mass% to 2 mass% is more preferable.

  The produced protective agent block is used by being attached to a base material such as a metal, an alloy, or plastic with an adhesive or the like.

(Protective layer forming device)
The protective layer forming apparatus of the present invention comprises a protective agent supplying means for supplying a photosensitive agent protective agent to the surface of the photosensitive member,
A pressing means for pressing the protective agent for a photoreceptor of the present invention to the protective agent supply means;
And a thinning means for thinning the layer made of the protective agent for the photoreceptor supplied to the surface of the photoreceptor by the protective agent supply means, and further includes other means as necessary.
Further, the thinning means in the protective layer forming apparatus may also serve as a cleaning means. However, in order to form the protective layer more reliably, the residual material mainly composed of toner on the photoreceptor is previously removed by the cleaning means. It is preferable to remove the residue so that the residue does not enter the protective layer.

Here, FIG. 5 is a schematic view showing an example of the protective layer forming apparatus of the present invention.
The protective layer forming apparatus 2 disposed facing the photosensitive drum 1 as the photosensitive member mainly includes the protective agent block 21, the protective agent supply means 22, the pressing means 23, the thinning means 24, and the like of the present invention. Composed.

  The protective agent block 21, which is a protective agent for a photoconductor of the present invention, is brought into contact with, for example, a brush-like protective agent supply unit 22 by a pressing force from the pressing unit 23. The protective agent supply means 22 rotates and rubs with the photosensitive member 1 with a linear velocity difference. At this time, the protective agent held on the surface of the protective agent supply means is supplied to the surface of the photosensitive member.

  Since the protective agent supplied to the surface of the photoconductor may not be a sufficient protective layer when supplied, it is thinned by a thinning means with a blade-like member, for example, in order to form a more uniform protective layer. It becomes a protective layer.

  The photosensitive member on which the protective layer is formed can be discharged in a minute gap by bringing the charging roller 3 to which a DC voltage or a voltage obtained by superimposing an AC voltage is applied with a high voltage power source (not shown) into contact or close proximity. The photosensitive member is charged by. At this time, a part of the protective layer is decomposed or oxidized due to electrical stress, and air discharge products adhere to the surface of the protective layer, resulting in a deteriorated product.

  The deteriorated protective agent is removed by the cleaning means together with the components such as the toner remaining on the photosensitive member by a normal cleaning means. Such cleaning means may be used in combination with the above-described thinning means, but the function of removing the photoreceptor surface residue and the function of forming the protective layer differ in the rubbing state of appropriate members. Therefore, it is preferable to separate the functions and provide the cleaning unit 4 including the cleaning unit 41, the cleaning pressing mechanism 42, and the like upstream of the protective agent supply unit as shown in FIG.

  The blade material used for the thinning means is not particularly limited and can be appropriately selected from known materials for cleaning blades according to the purpose. For example, urethane rubber, hydrin rubber, silicone rubber, fluorine For example, rubber. These may be used individually by 1 type and may use 2 or more types together. These blades may be coated or impregnated with a low friction coefficient material at the contact point with the photoreceptor. Moreover, in order to adjust the hardness of an elastic body, you may disperse fillers, such as an organic filler and an inorganic filler.

  The thinning means may be installed in either the counter direction or the trading direction with respect to the rotation direction of the photoconductor, but the force to stretch the protective agent on the photoconductor is better when installed in the counter direction. Becomes stronger. Therefore, even if the linear velocity of the photosensitive member is increased, the protective agent can be quickly stretched on the photosensitive member, which is preferable.

  The cleaning blade is fixed to the blade support by any method such as adhesion or fusion so that the tip can be pressed against the surface of the photoreceptor. The thickness of the blade cannot be uniquely defined in view of the force applied by pressing, but is preferably 0.5 mm to 5 mm, and more preferably 1 mm to 3 mm.

  Also, the length of the cleaning blade that protrudes from the support and can bend, that is, the so-called free length, is not unambiguously defined in consideration of the force applied by pressing, but is preferably 1 mm to 15 mm. 2 mm to 10 mm is more preferable.

  As another configuration of the protective layer forming blade member, the surface of the elastic metal blade such as a spring plate is coated with a coating layer of resin, rubber, elastomer or the like via a coupling agent or a primer component as necessary. It may be formed by a method such as dipping, heat-cured or the like if necessary, and further subjected to surface polishing if necessary.

  The coating layer contains at least a binder resin and a filler, and further contains other components as necessary.

  The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include fluorine resins such as PFA, PTFE, FEP, and PVdF; silicone elastomers such as fluorine rubber and methylphenyl silicone elastomer; Is mentioned.

  The thickness of the elastic metal blade is preferably 0.05 mm to 3 mm, more preferably 0.1 mm to 1 mm. In the elastic metal blade, in order to suppress twisting of the blade, a process such as bending may be performed in a direction substantially parallel to the support shaft after the attachment.

  The force for pressing the photoconductor with the thinning means is sufficient to spread the protective agent to the state of the protective layer, and the linear pressure is preferably 5 gf / cm to 80 gf / cm, and 10 gf / cm to 60 gf / cm. cm is more preferable.

  A brush-like member is preferably used as the protective agent supply means. In this case, the brush fiber is preferably flexible in order to suppress mechanical stress on the surface of the photoreceptor. The material of the flexible brush fiber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyolefin resin (for example, polyethylene, polypropylene); polyvinyl resin or polyvinylidene resin (for example, Polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone); vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; styrene- Butadiene resin; fluororesin (eg, polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene); polyester; nylon; acrylic; rayon; ; Polycarbonate; phenolic resins; amino resins (e.g. urea - formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins).

  In order to adjust the degree of bending, for example, diene rubber, styrene-butadiene rubber (SBR), ethylene propylene rubber, isoprene rubber, nitrile rubber, urethane rubber, silicone rubber, hydrin rubber, norbornene rubber, etc. may be combined. .

The support for the protective agent supply means includes a fixed mold and a rotatable roll. Examples of the roll-shaped supply member include a roll brush obtained by winding a tape having brush fibers piled around a metal core bar in a spiral shape. The brush fiber has a fiber diameter of 10 μm to 500 μm, the length of the brush fiber is 1 mm to 15 mm, and the brush density is 10,000 to 300,000 per square inch (1.5 × 10 ^{7 to} 4.5 × per square meter). 10 ⁸ ) is preferable.

  The protective agent supply means preferably uses a high brush density in terms of supply uniformity and supply stability, and a single fiber is made from several to several hundreds of fine fibers. It is preferable. For example, bundling 50 fine fibers of 6.7 decitex (6 denier), such as 333 decitex = 6.7 decitex × 50 filament (300 denier = 6 denier × 50 filament), and implanting as one fiber Is preferred.

  Moreover, you may provide a coating layer in the brush surface for the purpose of stabilizing the surface shape, environmental stability, etc. of a brush as needed. As a component constituting the coating layer, it is preferable to use a coating layer component that can be deformed according to the bending of the brush fiber. The coating layer component is not particularly limited as long as it is a material that can maintain flexibility, and can be appropriately selected according to the purpose. For example, polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene, etc. Polyolefin resin: Polystyrene such as polystyrene, acrylic (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polybiliketone, or polyvinylidene resin such as polyvinyl chloride-acetic acid Vinyl copolymer; silicone resin composed of organosiloxane bonds or modified products thereof (modified products such as alkyd resin, polyester resin, epoxy resin, polyurethane resin, etc.); Fluororesins such as oloalkyl ether, polyfluorovinyl, polyfluorovinylidene, polychlorotrifluoroethylene; polyamides; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; epoxy resins or composite resins thereof It is done.

(Image forming method and image forming apparatus)
The image forming method used in the present invention includes at least an electrostatic latent image forming step, a developing step, a transfer step, a protective layer forming step, and a fixing step, preferably a cleaning step, and further if necessary. And other processes selected as appropriate, for example, a static elimination process, a recycling process, a control process, and the like.

  The image forming apparatus of the present invention comprises at least a photosensitive member, an electrostatic latent image forming unit, a developing unit, a transfer unit, a protective layer forming unit, and a fixing unit, and preferably has a cleaning unit. In addition, other means appropriately selected as necessary, for example, static elimination means, recycling means, control means and the like are provided.

  The image forming method used in the present invention can be preferably implemented by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming unit, and the developing step can be performed. The transfer unit can be performed by the developing unit, the transfer step can be performed by the transfer unit, the protective layer forming step can be performed by the protective layer forming unit, and the fixing step can be performed by the fixing unit. The other steps can be performed by the other means.

  In the image forming apparatus according to the present invention, the linear velocity of the photosensitive member can be uniformly applied on the photosensitive member regardless of the linear velocity, so that high-quality image formation can be performed over time. However, particularly when the linear velocity of the photosensitive member is 180 mm / second or more, further 250 mm / second or more, it is impossible to form a high-quality image over time unless the protective agent of the present invention is used.

<Electrostatic latent image forming step and electrostatic latent image forming means>
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the photoreceptor.
-Photoconductor-
The photoconductor (hereinafter also referred to as “electrostatic latent image carrier” or “electrophotographic photoconductor”) is not particularly limited in terms of its material, shape, structure, size, etc. The shape is preferably a drum shape, and examples of the material include inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors such as polysilane and phthalopolymethine. It is done.

  The photoreceptor used in the image forming apparatus of the present invention comprises a conductive support, and at least a photosensitive layer on the conductive support, and further comprises other layers as necessary.

  As the photosensitive layer, a single layer type in which a charge generation material and a charge transport material are mixed, a forward layer type in which a charge transport layer is provided on the charge generation layer, or a charge generation layer is provided on the charge transport layer. There is a reverse layer type. In order to improve the mechanical strength, abrasion resistance, gas resistance, cleaning property, etc. of the photoreceptor, an outermost surface layer can be provided on the photosensitive layer. An undercoat layer may be provided between the photosensitive layer and the conductive support. Moreover, an appropriate amount of a plasticizer, an antioxidant, a leveling agent or the like can be added to each layer as necessary.

-Support-
The support is not particularly limited as long as it has a volume resistance of 1.0 × 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. For example, aluminum, nickel, Metals such as chrome, nichrome, copper, gold, silver, platinum, metal oxides such as tin oxide and indium oxide, film or cylindrical plastic, paper coated, or aluminum, aluminum by vapor deposition or sputtering A plate made of an alloy, nickel, stainless steel, or the like, and a tube subjected to surface treatment such as cutting, superfinishing, or polishing after being formed into a drum shape by a method such as extrusion or drawing can be used.

The drum-shaped support preferably has a diameter of 20 mm to 150 mm, more preferably 24 mm to 100 mm, and still more preferably 28 mm to 70 mm. When the diameter of the drum-shaped support is less than 20 mm, it may be physically difficult to arrange each step of charging, exposure, development, transfer, and cleaning around the drum. When the diameter exceeds 150 mm, The image forming apparatus may become large. In particular, when the image forming apparatus is a tandem type, since it is necessary to mount a plurality of photoconductors, the diameter is preferably 70 mm or less, and more preferably 60 mm or less.
Further, an endless nickel belt or an endless stainless steel belt as disclosed in JP-A-52-36016 can also be used as the conductive support.

  The undercoat layer of the photoconductor may be composed of a single layer or a plurality of layers. For example, (1) the resin is the main component, and (2) the white pigment and the resin are the main components. And (3) a metal oxide film obtained by chemically or electrochemically oxidizing the surface of a conductive substrate. Among these, those containing a white pigment and a resin as main components are preferable. Examples of the white pigment include metal oxides such as titanium oxide, aluminum oxide, zirconium oxide, and zinc oxide. Among these, titanium oxide is particularly preferable because it is excellent in preventing injection of charges from the conductive support.

  Examples of the resin include thermoplastic resins such as polyamide, polyvinyl alcohol, casein, and methyl cellulose; thermosetting resins such as acrylic, phenol, melamine, alkyd, unsaturated polyester, and epoxy. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular in the thickness of the said undercoat layer, According to the objective, it can select suitably, 0.1-10 micrometers is preferable and 1-5 micrometers is more preferable.

  Examples of the charge generation material in the photosensitive layer include monoazo pigments, bisazo pigments, trisazo pigments, tetrakisazo pigments and other azo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, Cyanine dyes, styryl dyes, pyrylium dyes, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indanthrone pigments, squarylium pigments, phthalocyanine pigments, etc. Organic pigments or dyes; selenium, selenium-arsenic, selenium-tellurium, cadmium sulfide, zinc oxide, titanium oxide, amorphous silicon, and other inorganic materials. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the charge transport material in the photosensitive layer include anthracene derivatives, pyrene derivatives, carbazole derivatives, tetrazole derivatives, metallocene derivatives, phenothiazine derivatives, pyrazoline compounds, hydrazone compounds, styryl compounds, styryl hydrazone compounds, enamine compounds, butadiene compounds, distyryl. Examples thereof include compounds, oxazole compounds, oxadiazole compounds, thiazole compounds, imidazole compounds, triphenylamine derivatives, phenylenediamine derivatives, aminostilbene derivatives, and triphenylmethane derivatives. These may be used individually by 1 type and may use 2 or more types together.

  As the binder resin used to form the photosensitive layer, it is electrically insulating and may be a known thermoplastic resin, thermosetting resin, photocurable resin, photoconductive resin, or the like. it can. Examples of the binder resin include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, Polyvinyl acetal, polyester, phenoxy resin, (meth) acrylic resin, polystyrene, polycarbonate, polyarylate, polysulfone, polyethersulfone, ABS resin and other thermoplastic resins, phenol resin, epoxy resin, urethane resin, melamine resin, isocyanate Examples thereof include thermosetting resins such as resins, alkyd resins, silicone resins, thermosetting acrylic resins, polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the antioxidant include phenolic compounds, paraphenylenediamines, organic sulfur compounds, and organic phosphorus compounds.

  Examples of the phenol compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl- 6-t-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3 -Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy Ben ) Benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3 ′) -T-butylphenyl) butyric acid] cricol ester, tocopherols and the like.

  Examples of the paraphenylenediamines include N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl- Examples include p-phenylenediamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like.

  Examples of the hydroquinones include 2,5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methyl. Examples include hydroquinone and 2- (2-octadecenyl) -5-methylhydroquinone.

  Examples of the organic sulfur compounds include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like. .

  Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant is preferably 0.01 to 10% by mass with respect to the total mass of the layer to be added.

  As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is preferably 30 parts by mass or less with respect to 100 parts by mass of the binder resin. .

  Further, a leveling agent may be added to the photosensitive layer. Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil; polymers having a perfluoroalkyl group in the chain or oligomers. As for the usage-amount of the said leveling agent, 0-1 mass part is preferable with respect to 100 mass parts of said binder resins.

  The outermost surface layer of the photoreceptor is provided to improve the mechanical strength, abrasion resistance, gas resistance, cleaning properties, and the like of the photoreceptor. As the outermost surface layer, a polymer having a mechanical strength higher than that of the photosensitive layer and a material in which an inorganic filler is dispersed in the polymer are suitable. The resin used for the outermost surface layer may be either a thermoplastic resin or a thermosetting resin, but the thermosetting resin has high mechanical strength and suppresses abrasion due to friction with the cleaning blade. This is particularly preferable because of its extremely high capacity. If the surface layer is thin, there is no problem even if it does not have the charge transport capability, but if the surface layer without the charge transport capability is formed thick, the sensitivity of the photoreceptor decreases, the potential increases after exposure, and the residual layer Since the potential rise is likely to occur, it is preferable to include the above-described charge transport material in the surface layer or to use a polymer having charge transport ability as the polymer used in the surface layer.

  Since the mechanical strength of the photosensitive layer and the outermost surface layer is generally greatly different, the outermost surface layer is worn away due to friction with the cleaning blade. It is important that the outermost surface layer has a sufficient thickness, preferably 0.1 μm to 12 μm, more preferably 1 μm to 10 μm, and still more preferably 2 μm to 8 μm. When the thickness is less than 0.1 μm, it is too thin and tends to disappear partially due to friction with the cleaning blade, and wear of the photosensitive layer may proceed from the disappeared portion, and when it exceeds 12 μm, Decrease in sensitivity, increase in potential after exposure, and increase in residual potential are likely to occur. Particularly when a polymer having charge transport ability is used, the cost of the polymer having charge transport ability may be increased.

  The resin used for the outermost surface layer is preferably one that is transparent to writing light at the time of image formation and excellent in insulation, mechanical strength, and adhesion. For example, ABS resin, ACS resin, olefin-vinyl monomer Copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin , Polymethyl bentene, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin, etc. And the like. These polymers may be thermoplastic resins, but in order to increase the mechanical strength of the polymers, they are crosslinked with a crosslinking agent having a polyfunctional acryloyl group, carboxyl group, hydroxyl group, amino group, etc. By using a functional resin, the mechanical strength of the outermost surface layer is increased, and wear due to friction with the cleaning blade can be greatly reduced.

  The outermost surface layer preferably has a charge transporting capability. In order to provide the outermost surface layer with a charge transporting capability, the polymer used for the outermost surface layer and the above-described charge transporting material are mixed and used. A method using a polymer having a charge transporting capability for the outermost surface layer is conceivable, and the latter method is preferable because a high-sensitivity photoconductor with little increase in potential after exposure and little increase in residual potential can be obtained.

  Preferred examples of the polymer having the charge transport layer ability include those having a group represented by the following structural formula (1) as the group having the charge transport ability in the polymer.

However, in the structural formula (1), Ar ₁ represents an arylene group which may have a substituent. Ar ₂ and Ar ₃ may be the same as or different from each other, and each represents an aryl group that may have a substituent.

  Such a group having a charge transporting ability is preferably added to a side chain of a polymer having high mechanical strength such as a polycarbonate resin and an acrylic resin, and the monomer can be easily produced, and the coating property and curability are also improved. It is particularly preferable to use an excellent acrylic resin.

  The acrylic resin having such a charge transporting capability is a surface layer having high mechanical strength, excellent transparency, and high charge transporting capability by polymerizing the unsaturated carboxylic acid having the group of the structural formula (1). Can be formed. Further, the acrylic resin has a crosslinked structure by mixing a polyfunctional unsaturated carboxylic acid, preferably a tri- or higher functional unsaturated carboxylic acid, with the monofunctional unsaturated carboxylic acid having the group of the structural formula (1). When formed, it becomes a thermosetting polymer, and the mechanical strength of the surface layer becomes extremely high. The polyfunctional unsaturated carboxylic acid may be added with the group of the structural formula (1). However, since the production cost of the monomer is increased, the polyfunctional unsaturated carboxylic acid has the structure described above. It is preferable to use a photocurable polyfunctional monomer without adding the group of the formula (1).

  Examples of the monofunctional unsaturated carboxylic acid having a group represented by the structural formula (1) include the following structural formula (2) or structural formula (3).

In Structural Formula (2) and Structural Formula (3), R ₁ is a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. An aryl group which may have a cyano group, a nitro group, an alkoxy group which may have a substituent, -COOR ₇ (wherein R ₇ is a hydrogen atom, an alkyl which may have a substituent) Group, an aralkyl group which may have a substituent, or an aryl group which may have a substituent, a carbonyl halide group, CONR ₈ R ₉ (where R ₈ and R ₉ are It may be the same or different, and has a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents an aryl group which may be Represent.

In Structural Formula (2) and Structural Formula (3), Ar ₁ and Ar ₂ may be the same as or different from each other, and represent an arylene group that may have a substituent.
In Structural Formula (2) and Structural Formula (3), Ar ₃ and Ar ₄ may be the same as or different from each other and represent an aryl group that may have a substituent.

In the structural formulas (2) and (3), X has a single bond, an alkylene group which may have a substituent, a cycloalkylene group which may have a substituent, or a substituent. Represents an alkylene ether group, an oxygen atom, a sulfur atom or a vinylene group which may be substituted.
In Structural Formula (2) and Structural Formula (3), Z has an alkylene group which may have a substituent, an alkylene ether divalent group which may have a substituent, or a substituent. Represents an optionally substituted alkyleneoxycarbonyl divalent group.
m and n each represent an integer of 0 to 3.

In the structural formulas (2) and (3), examples of the alkyl group in the substituent of R ₁ include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the aralkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. These include halogen atoms, nitro groups, cyano groups; alkyl groups such as methyl groups and ethyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups; aryl groups such as phenyl groups and naphthyl groups; It may be substituted with an aralkyl group such as a benzyl group or a phenethyl group. Of these R ₁ substituents, a hydrogen atom or a methyl group is particularly preferred.

Examples of the aryl group of Ar ₃ and Ar ₄ include a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group.

  As the condensed polycyclic hydrocarbon group, those having 18 or less carbon atoms forming a ring are preferable. For example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group, s-indacenyl group, fluorenyl group, acenaphthylenyl group, pleyadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group, Examples include a chrycenyl group and a naphthacenyl group.

  Examples of the non-condensed cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether, diphenyl sulfone; biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne , Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene; ring assembly carbonization such as 9,9-diphenylfluorene And monovalent groups of hydrogen compounds.

  Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

  The content of the polyfunctional unsaturated carboxylic acid is preferably 5% by mass to 75% by mass of the entire outermost surface layer, more preferably 10% by mass to 70% by mass, and still more preferably 20% by mass to 60% by mass. . When the content is less than 5% by mass, the mechanical strength of the outermost surface layer is insufficient, and when it exceeds 75% by mass, cracks are likely to occur when a strong force is applied to the outermost surface layer. Sensitivity deterioration may occur easily.

  When an acrylic resin is used for the outermost surface layer, after applying the unsaturated carboxylic acid to the photoreceptor, electron beam irradiation or actinic rays such as ultraviolet rays are irradiated to cause radical polymerization to form a surface layer can do. When performing radical polymerization with actinic rays, a solution obtained by dissolving a photopolymerization initiator in an unsaturated carboxylic acid is used. As the photopolymerization initiator, materials that are usually used for photocurable coatings can be used.

  The outermost surface layer preferably contains metal fine particles, metal oxide fine particles, and other fine particles in order to increase the mechanical strength of the outermost surface layer. Examples of the metal oxide include titanium oxide, aluminum oxide, tin oxide, potassium titanate, TiO, TiN, zinc oxide, indium oxide, and antimony oxide. Examples of the other fine particles include fluorine resins such as polytetrafluoroethylene, silicone resins, or those obtained by dispersing inorganic materials in these resins for the purpose of improving wear resistance.

  Next, the formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the photoconductor and then performing imagewise exposure, and can be performed by the electrostatic latent image forming unit. it can. The electrostatic latent image forming unit includes, for example, at least a charger that uniformly charges the surface of the photoconductor and an exposure device that exposes the surface of the photoconductor imagewise.

  The charging can be performed, for example, by applying a voltage to the surface of the photoreceptor using the charger.

The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers utilizing corona discharge such as corotrons and corotrons.
The charger preferably has voltage applying means for applying a voltage having an AC component.

The exposure can be performed, for example, by exposing the surface of the photoconductor imagewise using the exposure device.
The exposure device is not particularly limited as long as the surface of the photoreceptor charged by the charger can be exposed like an image to be formed, and can be appropriately selected according to the purpose. Examples thereof include various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system.
In the present invention, an optical backside system that performs imagewise exposure from the backside of the photoreceptor may be employed.

<Development process and development means>
The developing step is a step of developing the electrostatic latent image using a toner or a developer to form a visible image.

The visible image can be formed, for example, by developing the electrostatic latent image using the toner or the developer, and can be performed by the developing unit.
The developing unit is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. Preferred examples include those having at least a developing unit capable of bringing the toner or developer into contact or non-contact with the electrostatic latent image.

-Toner-
The toner preferably has an average circularity of 0.93 to 1.00, which is an average value of the circularity SR represented by the following formula 1, and more preferably 0.95 to 0.99. The average circularity is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere, and the average circularity becomes smaller as the surface shape becomes more complicated.
<Formula 1>
Circularity SR = (perimeter of circle having the same area as the projected area of toner particles) / (perimeter of projected image of toner particles)
When the average circularity is in the range of 0.93 to 1.00, the surface of the toner particles is smooth, and the toner particles and the contact area between the toner particles and the photosensitive member are small, so that the transferability is excellent. Further, since the toner particles have no corners, the developer agitation torque in the developing device is small, and the agitation drive is stabilized, so that no abnormal image is generated. In addition, since there are no angular toner particles in the toner that forms the dots, the pressure is uniformly applied to the entire toner that forms the dots when pressed against the recording medium during transfer, and the transfer is not easily lost. Further, since the toner particles are not angular, the abrasive power of the toner particles itself is small, and the surface of the photoreceptor is not damaged or worn.

  The circularity SR can be measured using, for example, a flow type particle image analyzer (manufactured by Toa Medical Electronics Co., Ltd., FPIA-1000).

  First, 0.1 to 0.5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance. Add ~ 0.5g. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the shape and particle size of the toner are measured by the above apparatus with the dispersion concentration being 3000 to 10000 / μl.

  The toner has a mass average particle diameter (D4) of preferably 3 μm to 10 μm, and more preferably 4 μm to 8 μm. In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent. When the mass average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties may occur, and when it exceeds 10 μm, it is difficult to suppress scattering of characters and lines. There is.

  The ratio (D4 / D1) of the mass average particle diameter (D4) and the number average particle diameter (D1) of the toner is preferably 1.00 to 1.40, more preferably 1.00 to 1.30. The closer the ratio (D4 / D1) is to 1, the sharper the particle size distribution of the toner. In the range of (D4 / D1) from 1.00 to 1.40, selective development depending on the toner particle size. Since image quality does not occur, the image quality is excellent. In addition, since the toner particle size distribution is sharp, the triboelectric charge amount distribution is also sharp and the occurrence of fog is suppressed. Further, when the toner particle diameter is uniform, the latent image dots are developed so as to be arranged densely and orderly, so that the dot reproducibility is excellent.

  Here, the mass average particle diameter (D4) and the particle size distribution of the toner are measured by, for example, a Coulter counter method. Examples of the measuring device for the particle size distribution of toner particles by the Coulter counter method include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter).

  First, 0.1 to 5 ml of a surfactant (preferably alkyl benzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the volume and number of toner particles or toner using a 100 μm aperture as the aperture. Volume distribution and number distribution are calculated. From the obtained distribution, the mass average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

  As a channel, it is 2.00 micrometers or more and less than 2.52 micrometers; 2.52 micrometers or more and less than 3.17 micrometers; 3.17 micrometers or more and less than 4.00 micrometers; 4.00 micrometers or more and less than 5.04 micrometers; 5.04 micrometers or more and less than 6.35 micrometers; .35 μm or more and less than 8.00 μm; 8.00 μm or more and less than 10.08 μm; 10.08 μm or more and less than 12.70 μm; 12.70 μm or more and less than 16.00 μm; 16.00 μm or more and less than 20.20 μm; Less than 40 μm; 25.40 μm or more and less than 32.00 μm; 3 channels of 32.00 μm or more and less than 40.30 μm are used, and particles having a particle size of 2.00 μm or more and less than 40.30 μm are targeted.

  As such a toner having a substantially spherical shape, a toner composition containing a polyester-based prepolymer having a functional group containing a nitrogen atom, a polyester resin, a colorant, and a release agent in an aqueous medium in the presence of fine resin particles. Can be produced by crosslinking and / or extension reaction. The toner produced by this reaction can reduce the hot offset by curing the toner surface, and can prevent the fixing device from becoming dirty and appearing on the image.

  Examples of the polyester prepolymer having a functional group containing a nitrogen atom include a polyester prepolymer (A) having an isocyanate group, and examples of the compound that extends or crosslinks with the prepolymer include amines (B). Can be mentioned.

  Examples of the polyester prepolymer (A) having an isocyanate group include a polycondensate of a polyol (1) and a polycarboxylic acid (2) and a polyester having an active hydrogen group, which is further reacted with a polyisocyanate (3). Is mentioned. Examples of the active hydrogen group possessed by the polyester include a hydroxyl group (alcoholic hydroxyl group and phenolic hydroxyl group), an amino group, a carboxyl group, and a mercapto group. Among these, alcoholic hydroxyl groups are particularly preferable.

  Examples of the polyol (1) include diol (1-1), trivalent or higher polyol (1-2), (1-1) alone or (1-1) and a small amount of (1-2). Mixtures are preferred.

  Examples of the diol (1-1) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (Diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); Alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); Bisphenols (bisphenol A) Bisphenol F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the alicyclic diol Alkylene oxide of the bisphenols (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferable, and combined use of alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms is particularly preferable.

  Examples of the trivalent or higher polyol (1-2) include 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); (Trisphenol PA, phenol novolak, cresol novolak, etc.); alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polycarboxylic acid (2) include dicarboxylic acid (2-1) and trivalent or higher polycarboxylic acid (2-2). Among these, (2-1) alone and (2-1) ) And a small amount of (2-2).

  Examples of the dicarboxylic acid (2-1) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, Terephthalic acid, naphthalenedicarboxylic acid, etc.). Among these, alkenylene dicarboxylic acid having 4 to 20 carbon atoms and aromatic dicarboxylic acid having 8 to 20 carbon atoms are particularly preferable.

  Examples of the trivalent or higher polycarboxylic acid (2-2) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polycarboxylic acid (2), you may make it react with polyol (1) using the acid anhydride or lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) of the above-mentioned thing.

  As for the ratio of the polyol (1) and the polycarboxylic acid (2), the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH] is preferably 2/1 to 1/1. 5/1 to 1/1 is more preferable, and 1.3 / 1 to 1.02 / 1 is still more preferable.

  Examples of the polyisocyanate (3) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; Those blocked with caprolactam, etc. These may be used individually by 1 type and may use 2 or more types together.

  As for the ratio of the polyisocyanate (3), the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group is preferably 5/1 to 1/1. 1 to 1.2 / 1 is more preferable, and 2.5 / 1 to 1.5 / 1 is still more preferable. If the [NCO] / [OH] exceeds 5, the low-temperature fixability may be deteriorated. If the molar ratio of [NCO] is less than 1, the urea content in the modified polyester becomes low, and hot offset resistance Sex worsens.

  The content of the polyisocyanate (3) component in the prepolymer (A) having an isocyanate group at the terminal is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass. More preferably, the content is 20% by mass to 20% by mass. When the content is less than 0.5% by mass, the hot offset resistance deteriorates and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. When the content exceeds 40% by mass, low-temperature fixability is obtained. May get worse.

  The average number of isocyanate groups contained per molecule in the prepolymer (A) having the isocyanate group is preferably 1 or more, more preferably 1.5 to 3 on average, and 1.8 to 2.5 on average. Further preferred. When the number is less than 1 per molecule, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance may be deteriorated.

  As the amines (B), the diamine (B1), trivalent or higher polyamine (B2), amino alcohol (B3), amino mercaptan (B4), amino acid (B5), and amino groups of B1 to B5 were blocked. (B6) etc. are mentioned. Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane, Isophorone diamine etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine etc.) and the like. Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the B1-B5 amino group blocked (B6) include ketimine compounds and oxazoline compounds obtained from the B1-B5 amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  Furthermore, if necessary, the molecular weight of the urea-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), or those obtained by blocking them (ketimine compounds).

  The ratio of the amines (B) is the equivalent ratio [NCO] / [NHx] of the isocyanate group [NCO] in the prepolymer (A) having an isocyanate group and the amino group [NHx] in the amine (B). Is preferably 1/2 to 2/1, more preferably 1.5 / 1 to 1 / 1.5, and still more preferably 1.2 / 1 to 1 / 1.2. When the [NCO] / [NHx] exceeds 2 or less than 1/2, the molecular weight of the urea-modified polyester (i) becomes low, and the hot offset resistance deteriorates.

  In the present invention, the polyester (i) modified with a urea bond may contain a urethane bond together with a urea bond. The molar ratio between the urea bond content and the urethane bond content is preferably 100/0 to 10/90, more preferably 80/20 to 20/80, and still more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance may be deteriorated.

  By these reactions, the modified polyester used in the toner, especially the urea-modified polyester (i) can be produced. These urea-modified polyesters (i) are produced by a one-shot method or a prepolymer method. The mass average molecular weight of the urea-modified polyester (i) is preferably 10,000 or more, more preferably 20,000 to 10,000,000, and still more preferably 30,000 to 1,000,000. When the mass average molecular weight is less than 10,000, the hot offset resistance may be deteriorated.

  The number average molecular weight of the urea-modified polyester is not particularly limited when the unmodified polyester (ii) described later is used, and may be a number average molecular weight that can be easily obtained to obtain the mass average molecular weight. (I) When used alone, the number average molecular weight is preferably 20,000 or less, more preferably 1,000 to 10,000, and still more preferably 2,000 to 8,000. When the number average molecular weight exceeds 20,000, low temperature fixability and glossiness when used in a full color image forming apparatus may be deteriorated.

  In the present invention, not only the polyester (i) modified with a urea bond but also the polyester (ii) not modified can be included as a binder resin component together with the (i). By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color apparatus are improved, so that it is preferable to use alone. Examples of (ii) include the same polycondensates of polyol (1) and polycarboxylic acid (2) as in the polyester component (i), and preferred ones are also the same as (i). Further, (ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, for example, may be modified with a urethane bond. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance.

  Therefore, the polyester component (i) and (ii) preferably have similar compositions. When (ii) is contained, the mass ratio of (i) and (ii) is preferably 5/95 to 80/20, more preferably 5/95 to 30/70, and further preferably 5/95 to 25/75. 7/93 to 20/80 is particularly preferable. When the mass ratio of (i) is less than 5% by mass, the hot offset resistance may be deteriorated, and it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The peak molecular weight of (ii) is preferably 1,000 to 30,000, more preferably 1,500 to 10,000, and still more preferably 2,000 to 8,000. When the peak molecular weight is less than 1,000, the heat resistant storage stability may be deteriorated, and when it exceeds 10,000, the low temperature fixability may be deteriorated. The hydroxyl value of (ii) is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g to 120 mgKOH / g, still more preferably 20 mgKOH / g to 80 mgKOH / g. If the hydroxyl value is less than 5 mgKOH / g, it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The acid value of (ii) is preferably 1 mgKOH / g to 30 mgKOH / g, more preferably 5 mgKOH / g to 20 mgKOH / g. By having an acid value, it tends to be negatively charged.

  The glass transition temperature (Tg) of the binder resin is preferably 50 ° C to 70 ° C, more preferably 55 ° C to 65 ° C. When the glass transition temperature is less than 50 ° C., blocking of the toner during high-temperature storage may be deteriorated, and when it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Due to the coexistence of the urea-modified polyester resin, the toner used in the present invention tends to have good heat storage stability even when the glass transition point is low, as compared with known polyester-based toners.

As the storage elastic modulus of the binder resin, the temperature (TG ′) at which the measurement frequency is 20 Hz is 10,000 dyne / cm ² is preferably 100 ° C. or more, and more preferably 110 ° C. to 200 ° C. When the temperature (TG ′) is less than 100 ° C., the hot offset resistance may be deteriorated.

  As the viscosity of the binder resin, the temperature (Tη) at 1000 poise at a measurement frequency of 20 Hz is preferably 180 ° C. or less, and more preferably 90 ° C. to 160 ° C. When the temperature (Tη) exceeds 180 ° C., the low-temperature fixability deteriorates. That is, TG ′ is preferably higher than Tη from the viewpoint of achieving both low temperature fixability and hot offset resistance. In other words, the difference between TG ′ and Tη (TG′−Tη) is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, and still more preferably 20 ° C. or higher. The upper limit of the difference is not particularly limited. Further, from the viewpoint of achieving both heat-resistant storage stability and low-temperature fixability, the difference between Tη and Tg is preferably from 0 ° C to 100 ° C, more preferably from 10 ° C to 90 ° C, and even more preferably from 20 to 80 ° C.

The binder resin can be produced by the following method.
First, the polyol (1) and the polycarboxylic acid (2) are heated to 150 ° C. to 280 ° C. in the presence of an esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and are generated while reducing the pressure as necessary. Water is distilled off to obtain a polyester having a hydroxyl group. Subsequently, this is made to react with polyisocyanate (3) at 40 to 140 degreeC, and the prepolymer (A) which has an isocyanate group is obtained. Further, (A) is reacted with amines (B) at 0 ° C. to 140 ° C. to obtain a polyester modified with a urea bond. When reacting (3) and reacting (A) and (B), a solvent may be used as necessary.

  Examples of usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.), Inactive to isocyanate (3) such as ethers (tetrahydrofuran, etc.).

  When using polyester (ii) not modified with urea bond, (ii) is produced in the same manner as polyester having a hydroxyl group, and this is dissolved in the solution after completion of the reaction of (i). , Mix.

  Further, the toner used in the present invention can be produced by the following method, but is not limited thereto.

  The toner may be formed by reacting a dispersion made of a prepolymer (A) having an isocyanate group in an aqueous medium with (B), or using a urea-modified polyester (i) produced in advance. Good. As a method for stably forming a dispersion comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium, a toner raw material comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium is used. And a method of dispersing by shearing force.

  The prepolymer (A) and other toner compositions (hereinafter sometimes referred to as toner raw materials), colorants, colorant master batches, release agents, charge control agents, unmodified polyester resins, Mixing may be performed when the dispersion is formed in the medium, but it is more preferable to mix the toner raw materials in advance and then add and disperse the mixture in the aqueous medium. In the present invention, other toner raw materials such as a colorant, a release agent, and a charge control agent do not necessarily have to be mixed when forming particles in an aqueous medium. It may be added later. For example, after forming particles not containing a colorant, the colorant can be added by a known dyeing method.

  As the aqueous medium, water alone may be used, but a solvent miscible with water may be used in combination. Examples of miscible solvents include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.) and the like.

  The amount of the aqueous medium used relative to 100 parts by mass of the toner composition containing the urea-modified polyester (i) and the prepolymer (A) is preferably 50 parts by mass to 2,000 parts by mass, and 100 parts by mass to 1,000 parts by mass. More preferred. When the amount used is less than 50 parts by mass, the toner composition is poorly dispersed, and toner particles having a predetermined particle size may not be obtained. When the amount exceeds 2,000 parts by mass, it is not economical.

  Moreover, a dispersing agent can also be used as needed. It is preferable to use a dispersant because the particle size distribution becomes sharp and the dispersion is stable.

The dispersion method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. . In order to make the particle size of the dispersion 2 μm to 20 μm, the high speed shearing method is preferable.
When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is preferably 1,000 rpm to 30,000 rpm, and more preferably 5,000 rpm to 20,000 rpm. The dispersion time is not particularly limited and may be appropriately selected depending on the intended purpose. In the case of a batch method, it is usually 0.1 to 5 minutes. As temperature at the time of dispersion | distribution, 0 to 150 degreeC is preferable normally, and 40 to 98 degreeC is more preferable. Higher temperatures are preferred in that the dispersion made of urea-modified polyester (i) or prepolymer (A) has a low viscosity and is easy to disperse.

  In the step of synthesizing the urea-modified polyester (i) from the prepolymer (A), the amine (B) may be added and reacted before the toner composition is dispersed in the aqueous medium, or may be dispersed in the aqueous medium. An amine (B) may be added later to cause a reaction from the particle interface. In this case, urea-modified polyester is preferentially produced on the surface of the manufactured toner, and a concentration gradient can be provided inside the particles.

In the reaction, it is preferable to use a dispersant as necessary.
There is no restriction | limiting in particular as said dispersing agent, According to the objective, it can select suitably, For example, surfactant, a slightly water-soluble inorganic compound dispersing agent, a polymeric protective colloid, etc. are mentioned.
These may be used individually by 1 type and may use 2 or more types together. Among these, surfactants are preferable.

  Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

  Examples of the anionic surfactant include alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, and the like. Among these, those having a fluoroalkyl group are preferable. Examples of the anionic surfactant having a fluoroalkyl group include a fluoroalkylcarboxylic acid having 2 to 10 carbon atoms or a metal salt thereof, disodium perfluorooctanesulfonylglutamate, 3- [omega-fluoroalkyl (6 carbon atoms). -11) Oxy] -1-alkyl (carbon number 3-4) sodium sulfonate, 3- [omega-fluoroalkanoyl (carbon number 6-8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (Carbon number 11-20) carboxylic acid or its metal salt, perfluoroalkyl carboxylic acid (carbon number 7-13) or its metal salt, perfluoroalkyl (carbon number 4-12) sulfonic acid or its metal salt, perfluoro Octanesulfonic acid diethanolamide, N-propyl-N- (2-hydroxy Ethyl) perfluorooctanesulfonamide, perfluoroalkyl (carbon number 6-10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (carbon number 6-10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (carbon number) 6-16) Ethyl phosphate and the like. Examples of commercially available surfactants having a fluoroalkyl group include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.); Fluorard FC-93, FC-95, FC-98, FC -129 (manufactured by Sumitomo 3M Co., Ltd.); Unidyne DS-101, DS-102 (manufactured by Daikin Industries, Ltd.); Megafac F-110, F-120, F-113, F-191, F-812, F- 833 (manufactured by Dainippon Ink & Chemicals, Inc.); Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products); 100, F150 (manufactured by Neos) and the like.

  Examples of the cationic surfactant include amine salt type surfactants and quaternary ammonium salt type cationic surfactants. Examples of the amine salt type surfactant include alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, imidazolines, and the like. Examples of the quaternary ammonium salt type cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride and the like. . Among the cationic surfactants, aliphatic quaternary ammonium such as aliphatic primary, secondary or tertiary amine acids having a fluoroalkyl group, perfluoroalkyl (6 to 10 carbon atoms) sulfonamidopropyltrimethylammonium salt, etc. Salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like. Commercially available products of the cationic surfactant include, for example, Surflon S-121 (manufactured by Asahi Glass Co., Ltd.); Florard FC-135 (manufactured by Sumitomo 3M Co., Ltd.); Unidyne DS-202 (manufactured by Daikin Industries, Ltd.), MegaFuck F-150, F-824 (manufactured by Dainippon Ink & Chemicals, Inc.); Xtop EF-132 (manufactured by Tochem Products);

  Examples of the nonionic surfactant include fatty acid amide derivatives and polyhydric alcohol derivatives.

  Examples of the amphoteric surfactant include alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine, N-alkyl-N, N-dimethylammonium betaine and the like.

  Examples of the poorly water-soluble inorganic compound dispersant include tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite.

  Examples of the polymeric protective colloid include acids, (meth) acrylic monomers containing a hydroxyl group, vinyl alcohol or ethers of vinyl alcohol, esters of vinyl alcohol and a compound containing a carboxyl group, amides Examples thereof include homopolymers or copolymers such as compounds or their methylol compounds, chlorides, those having a nitrogen atom or a heterocyclic ring thereof, polyoxyethylenes, and celluloses.

Examples of the acids include acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, and the like. Examples of the (meth) acrylic monomer containing a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, and γ-acrylate. -Hydroxypropyl, γ-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate Glycerin monomethacrylate, N-methylol acrylamide, N-methylol methacrylamide and the like. Examples of the vinyl alcohol or ethers with vinyl alcohol include vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, and the like. Examples of the esters of vinyl alcohol and a compound containing a carboxyl group include vinyl acetate, vinyl propionate, and vinyl butyrate. Examples of the amide compound or these methylol compounds include acrylamide, methacrylamide, diacetone acrylamide acid, or these methylol compounds. Examples of the chlorides include acrylic acid chloride and methacrylic acid chloride. Examples of the homopolymer or copolymer such as those having a nitrogen atom or a heterocyclic ring thereof include vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, and ethylene imine. Examples of the polyoxyethylene are polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene Examples thereof include oxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, and polyoxyethylene nonyl phenyl ester. Examples of the celluloses include methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

  In the preparation of the dispersion, a dispersion stabilizer can be used as necessary. Examples of the dispersion stabilizer include acids that are soluble in acids and alkalis such as calcium phosphate salts.

When the dispersion stabilizer is used, the calcium phosphate salt can be removed from the fine particles by a method of dissolving the calcium phosphate salt with an acid such as hydrochloric acid and then washing with water or a method of decomposing with an enzyme.
In the preparation of the dispersion, a catalyst for the extension reaction or the crosslinking reaction can be used. Examples of the catalyst include dibutyltin laurate and dioctyltin laurate.

  Furthermore, in order to lower the viscosity of the toner composition, a solvent in which the urea-modified polyester (i) or the prepolymer (A) is soluble can be used. The use of a solvent is preferable in that the particle size distribution becomes sharp. The solvent is preferably volatile from the viewpoint of easy removal.

  The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene Chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, aromatic solvents such as toluene and xylene; halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferable, and aromatic solvents such as toluene and xylene are more preferable.

  300 mass parts or less are preferable, as for the usage-amount of the solvent with respect to 100 mass parts of said prepolymers (A), 100 mass parts or less are more preferable, and 25 mass parts-70 mass parts are still more preferable. When a solvent is used, it is removed by heating under normal pressure or reduced pressure after the elongation and / or crosslinking reaction.

  The elongation and / or cross-linking reaction time is selected depending on the reactivity depending on the combination of the isocyanate group structure of the prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 hours to 24 hours. Is more preferable. The reaction temperature is preferably 0 ° C to 150 ° C, more preferably 40 ° C to 98 ° C. Furthermore, a known catalyst can be used as necessary. Specific examples include dibutyltin laurate and dioctyltin laurate.

  In order to remove the organic solvent from the obtained emulsified dispersion, a method in which the temperature of the entire system is gradually raised to completely evaporate and remove the organic solvent in the droplets can be employed. It is also possible to spray the emulsified dispersion in a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, and also remove the aqueous dispersant by evaporating it. is there. As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air currents heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer, rotary kiln.

  When the particle size distribution at the time of emulsification dispersion is wide and washing and drying processes are performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classifying into a desired particle size distribution.

  In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Although classification operation may be performed after obtaining as powder after drying, it is preferable in terms of efficiency to be performed in a liquid. The unnecessary fine particles or coarse particles obtained can be returned to the kneading step and used for the formation of particles. At that time, unnecessary fine particles or coarse particles may be wet.

  The dispersant used is preferably removed from the obtained dispersion as much as possible, but it is preferable to carry out it simultaneously with the classification operation described above.

  By mixing the resulting dried toner powder with dissimilar particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or by giving mechanical impact force to the mixed powder By immobilizing and fusing on the surface, it is possible to prevent detachment of the foreign particles from the surface of the resulting composite particle.

  As specific means, (1) a method of applying an impact force to the mixture by blades rotating at high speed, (2) the mixture is injected into a high-speed air stream, accelerated, and particles or composite particles are mixed with an appropriate collision plate. There is a method of making it collide. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) is modified to reduce the pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron system (Made by Kawasaki Heavy Industries, Ltd.), automatic mortar and the like.

  As the colorant used in the toner, pigments and dyes conventionally used as toner colorants can be used. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, Aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6C lake, calco oil blue, chrome yellow, quinacridone red, benzidine yellow, rose bengal and the like can be used alone or in combination. Further, if necessary, in order to give the toner particles magnetic properties, for example, iron oxides such as ferrite, magnetite and maghemite; metals such as iron, cobalt and nickel, or alloys of these with other metals, etc. The magnetic component may be contained alone or in combination in the toner particles. These components can also be used as a colorant component.

  Further, the number average particle diameter of the colorant in the toner used in the present invention is preferably 0.5 μm or less, more preferably 0.4 μm or less, and further preferably 0.3 μm or less. When the number average particle diameter exceeds 0.5 μm, the dispersibility of the pigment does not reach a sufficient level, and preferable transparency may not be obtained. On the other hand, the colorant having a fine particle diameter of less than 0.1 μm is sufficiently smaller than a half wavelength of visible light, and thus is considered not to adversely affect the light reflection and absorption characteristics. Therefore, the colorant particles having a number average particle size of less than 0.1 μm contribute to good color reproducibility and transparency of the OHP sheet having a fixed image. On the other hand, when there are many colorants having a particle size larger than 0.5 μm, the transmission of incident light is hindered or scattered, and the brightness of the projected image of the OHP sheet is reduced. There is a tendency to decrease the color. Further, when a large amount of colorant having a particle size larger than 0.5 μm is present, the colorant is detached from the surface of the toner particles, which may cause various problems such as fogging, drum contamination, and poor cleaning. The colorant having a particle size larger than 0.7 μm is preferably 10% by number or less, more preferably 5% by number or less of the total colorant.

  Further, by mixing the colorant together with part or all of the binder resin in advance after adding a wetting liquid, the binder resin and the colorant are initially sufficiently attached, In the subsequent toner production process, the colorant is dispersed more effectively in the toner particles, the dispersed particle diameter of the colorant is reduced, and better transparency can be obtained.

  As the binder resin used for kneading in advance, the resins exemplified as the binder resin for toner can be used as they are, but are not limited thereto.

  As a specific method for kneading the mixture of the binder resin and the colorant with the wetting liquid in advance, for example, the binder resin, the colorant and the wetting liquid are obtained after mixing with a blender such as a Henschel mixer. The obtained mixture is kneaded at a temperature lower than the melting temperature of the binder resin by a kneader such as a two-roll or three-roll to obtain a sample.

  Further, as the wetting liquid, a general one can be used in consideration of the solubility of the binder resin and the paintability with the colorant, but an organic solvent such as acetone, toluene, butanone, and water are used as the colorant. It is preferable from the viewpoint of dispersibility. Among these, the use of water is particularly preferable from the viewpoint of environmental considerations and maintaining the dispersion stability of the colorant in the subsequent toner production process.

  According to this manufacturing method, not only the particle diameter of the colorant particles contained in the obtained toner is reduced, but also the uniformity of the dispersion state of the particles is increased, so that the color reproducibility of the projected image by OHP is further improved. Get better.

The toner preferably contains a release agent together with the binder resin and the colorant.
The release agent is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax) And waxes containing carbonyl groups. Among these, a carbonyl group-containing wax is particularly preferable.

  Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1 , 18-octadecanediol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylenediamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide) Etc.); dialkyl ketones (distearyl ketone, etc.) and the like. Among these, polyalkanoic acid esters are particularly preferable.

  The release agent has a melting point of preferably 40 ° C to 160 ° C, more preferably 50 ° C to 120 ° C, and still more preferably 60 ° C to 90 ° C. When the melting point is less than 40 ° C., the heat resistant storage stability may be adversely affected. When the melting point exceeds 160 ° C., cold offset may easily occur during fixing at a low temperature.

  The mold release agent has a melt viscosity of preferably 5 cps to 1,000 cps, more preferably 10 cps to 100 cps at a temperature 20 ° C. higher than the melting point. When the melt viscosity exceeds 1,000 cps, the effect of improving hot offset resistance and low-temperature fixability may be poor.

  The content of the release agent in the toner is preferably 40% by mass or less, and more preferably 3% by mass to 30% by mass.

  Further, in order to accelerate the toner charge amount and its rise, a charge control agent may be contained in the toner as necessary. Since a color change occurs when a colored material is used as the charge control agent, a colorless or nearly white material is preferable.

  The charge control agent is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, triphenylmethane dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, Examples include quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, metal salts of salicylic acid derivatives, and the like.

  As the charge control agent, a commercially available product can be used. Examples of the commercially available product include quaternary ammonium salt Bontron P-51, oxynaphthoic acid metal complex E-82, and salicylic acid metal complex. E-84, E-89 of phenol-based condensate (both manufactured by Orient Chemical Co., Ltd.); TP-302, TP-415 of quaternary ammonium salt molybdenum complex (both manufactured by Hodogaya Chemical Co., Ltd.) ); Quaternary ammonium salt copy charge PSY VP2038, triphenylmethane derivative copy blue PR, quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (both manufactured by Hoechst); LRA-901, LR-147 which is a boron complex (all manufactured by Nippon Carlit Co., Ltd.), quinacrid And azo pigments, and other polymer compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.

  The amount of the charge control agent added varies depending on the type of the binder resin, the presence or absence of the additive, the toner production method including the dispersion method, and the like, and cannot be uniquely defined. 0.1 mass part-10 mass parts are preferable, and 0.2 mass part-5 mass parts are more preferable. When the addition amount exceeds 10 parts by mass, the chargeability of the toner is too large, the effect of the charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the flowability of the developer is decreased, The image density may be lowered. These charge control agents can be melted and kneaded together with a masterbatch and resin and then dissolved and dispersed, or they can be added directly when dissolved and dispersed in an organic solvent, or fixed after the toner particles are prepared on the toner surface. You may let them.

Further, when the toner composition is dispersed in the aqueous medium during the toner production process, resin fine particles mainly for stabilizing the dispersion may be added.
The resin fine particles may be any resin as long as it can form an aqueous dispersion, and may be a thermoplastic resin or a thermosetting resin. For example, vinyl resins, polyurethane resins, epoxy resins, polyester resins , Polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate resin and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, a vinyl resin, a polyurethane resin, an epoxy resin, a polyester resin, or a combination thereof is preferable because an aqueous dispersion of fine spherical resin particles can be easily obtained.

  As the vinyl resin, a polymer obtained by homopolymerization or copolymerization of a vinyl monomer is used. For example, a styrene- (meth) acrylic acid ester resin, a styrene-butadiene copolymer, a (meth) acrylic acid-acrylic acid ester. Examples thereof include a polymer, a styrene-acrylonitrile copolymer, a styrene-maleic anhydride copolymer, and a styrene- (meth) acrylic acid copolymer.

  In addition, inorganic fine particles are suitable as an external additive for assisting the fluidity, developability and chargeability of the toner particles.

  Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, and diatomaceous earth. , Chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like.

The primary particle diameter of the inorganic fine particles is preferably 5 nm to 2 μm, and more preferably 5 nm to 500 nm. The specific surface area of the inorganic fine particles by BET method is preferably 20 to 500 m ² / g. The addition amount of the inorganic fine particles in the toner is preferably 0.01% by mass to 5% by mass, and more preferably 0.01% by mass to 2.0% by mass.

  Other polymer fine particles such as polystyrene, methacrylic acid ester and acrylic acid ester copolymer obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, polycondensation system such as silicone, benzoguanamine and nylon, thermosetting resin And polymer particles.

A fluidizing agent can also be added to the toner. The fluidizing agent performs surface treatment to increase hydrophobicity, and can prevent deterioration of flow characteristics and charging characteristics even under high humidity.
Examples of the fluidizing agent include a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, an aluminum coupling agent, silicone oil, and modified silicone oil. Can be mentioned.

  In addition, examples of cleaning improvers for removing the developer after transfer remaining on the photosensitive member and the intermediate transfer member include metal soaps such as zinc stearate, calcium stearate, and stearic acid; polymethyl methacrylate fine particles, polystyrene fine particles And polymer fine particles produced by soap-free emulsion polymerization. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 μm to 1 μm.

  By using such a toner, as described above, it is possible to form a high-quality toner image having excellent development stability.

  Further, the image forming apparatus of the present invention can be applied not only to the combined use with the above-described polymerization method toner suitable for obtaining a high quality image, but also to an irregular shaped toner by a pulverization method, Even in this case, the life of the apparatus can be greatly extended. As a material constituting such a pulverized toner, those usually used as an electrophotographic toner can be applied without particular limitation.

  As the binder resin used in the pulverized toner, for example, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, or the like, or a substituted polymer thereof; styrene / p-chlorostyrene copolymer, styrene / propylene Copolymer, styrene / vinyl toluene copolymer, styrene / vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / acrylic Octyl acid copolymer, styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, styrene / acrylonitrile copolymer Styrene / vinyl methyl ketone copolymer, Styrene copolymers such as tylene / butadiene copolymers, styrene / isoprene copolymers, styrene / maleic acid copolymers; polymethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polybutyl methacrylate, etc. Acrylic ester-based homopolymers or copolymers thereof; polyvinyl derivatives such as polyvinyl chloride and polyvinyl acetate; polyester-based polymers, polyurethane-based polymers, polyamide-based polymers, polyimide-based polymers, polyol-based polymers, Examples thereof include epoxy polymers, terpene polymers, aliphatic or alicyclic hydrocarbon resins, and aromatic petroleum resins. These may be used individually by 1 type and may use 2 or more types together. Among these, a styrene-acrylic copolymer resin, a polyester resin, and a polyol resin are preferable from the viewpoint of electrical characteristics, cost, and the like, and further, polyester resins and polyol resins are preferable as those having good fixing characteristics. Particularly preferred.

  In the pulverized toner, together with these resin components, the colorant component, wax component, charge control component and the like as described above are premixed as necessary, and then kneaded at a temperature close to the melting temperature of the resin component, and then cooled. Thereafter, a toner may be prepared through a pulverizing and classifying step, and the external additive component may be appropriately added and mixed as necessary.

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a toner having a stirrer for charging the toner or the developer by frictional stirring and a rotatable magnet roller is preferable.

  In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the photoconductor, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is applied to the surface of the photoconductor by an electric attractive force. Moving. As a result, the electrostatic latent image is developed with the toner to form a visible image with the toner on the surface of the photoreceptor.

  The developer accommodated in the developing device is a developer containing the toner, but the developer may be a one-component developer or a two-component developer.

<Transfer process and transfer means>
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably full color toner as the toner, and a composite transfer image; A mode including a secondary transfer step of transferring the transfer image onto the recording medium is more preferable.

  The transfer can be performed, for example, by charging the photoreceptor using a transfer charger, and can be performed by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred.

  The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

  The photosensitive member is an intermediate transfer member used for image formation by a so-called intermediate transfer method in which a toner image formed on a photosensitive member is primarily transferred to perform color superposition and further transferred to a recording medium. There may be.

-Intermediate transfer member-
As the intermediate transfer member, a material exhibiting conductivity of a volume resistance of 1.0 × 10 ^{5 to} 1.0 × 10 ¹¹ Ω · cm is preferable. When the volume resistance is less than 1.0 × 10 ⁵ Ω · cm, so-called transfer dust is generated in which the toner image is disturbed due to discharge when the toner image is transferred from the photosensitive member to the intermediate transfer member. If it exceeds 1.0 × 10 ¹¹ Ω · cm, the counter charge of the toner image remains on the intermediate transfer member after the toner image is transferred from the intermediate transfer member to a recording medium such as paper. May appear as an afterimage on other images.

  As the intermediate transfer member, for example, a metal oxide such as tin oxide or indium oxide, a conductive particle such as carbon black, or a conductive polymer, alone or in combination, kneaded with a thermoplastic resin, and then an extrusion-molded belt. A cylindrical or cylindrical plastic can be used. In addition, the above-mentioned conductive particles and conductive polymer are added to a resin liquid containing a thermal crosslinking reactive monomer or oligomer, if necessary, and centrifugal molding is performed while heating to obtain an intermediate transfer member on an endless belt. You can also.

When the surface layer is provided on the intermediate transfer member, among the surface layer materials used for the surface layer of the photoreceptor described above, the composition excluding the charge transport material is appropriately adjusted in combination with a conductive substance, Can be used.
The transfer unit (the primary transfer unit and the secondary transfer unit) preferably includes at least a transfer unit that peels and charges the visible image formed on the photoconductor toward the recording medium. There may be one transfer means or two or more transfer means. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.

  The recording medium is not particularly limited and can be appropriately selected from known recording media (recording paper).

<Protective layer forming step and protective layer forming means>
The protective layer forming step is a step of forming a protective layer by applying the protective agent of the present invention to the surface of the photoreceptor after transfer.
As the protective layer forming means, the protective layer forming apparatus of the present invention described above can be used.

<Fixing process and fixing means>
The fixing step is a step of fixing the visible image transferred to the recording medium using the fixing unit, and may be performed each time the toner of each color is transferred to the recording medium, or may be applied to the toner of each color. On the other hand, it may be carried out simultaneously at the same time in a state of being laminated.

The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose, but a known heating and pressing unit is preferable. Examples of the heating and pressing means include a combination of a heating roller and a pressing roller, a combination of a heating roller, a pressing roller, and an endless belt.
The heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the photoconductor, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited and may be any appropriate neutralization neutralizer as long as it can apply a neutralization bias to the photosensitive member. For example, a neutralization lamp is preferable. .

The cleaning step is a step of removing the electrophotographic toner remaining on the photoreceptor, and can be suitably performed by a cleaning unit.
The cleaning unit is preferably provided downstream of the transfer unit and upstream of the protective layer forming unit.

  The cleaning means is not particularly limited and may be selected from known cleaners as long as it can remove the electrophotographic toner remaining on the photoreceptor, and includes, for example, a magnetic brush cleaner, a static cleaner, and the like. Preferred examples include an electric brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.

The recycling step is a step of recycling the toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

Here, FIG. 7 is a cross-sectional view showing an example of the image forming apparatus 100 including the protective layer forming apparatus of the present invention.
Around the drum-shaped photoreceptors 1Y, 1M, 1C, and 1K, a protective layer forming device 2, a charging device 3, a latent image forming device 8, a developing device 5, a transfer device 6, and a cleaning device 4 are arranged, respectively. Image formation is performed by the above operation.

Next, a series of processes for image formation will be described using a negative-positive process.
A photoconductor represented by a photoconductor (OPC) having an organic photoconductive layer is neutralized by a static elimination lamp (not shown) or the like, and is uniformly negatively charged by a charging device 3 having a charging member.

  When the photosensitive member is charged by the charging device, an appropriate size suitable for charging the photosensitive members 1Y, 1M, 1C, and 1K to a desired potential from a voltage application mechanism (not shown) to the charging member. Or a charging voltage obtained by superimposing an AC voltage thereon is applied.

  The charged photoconductors 1Y, 1M, 1C, and 1K form a latent image with laser light irradiated by a latent image forming apparatus 8 such as a laser optical system (the absolute value of the exposed portion potential is the absolute value of the non-exposed portion potential). Is lower than the value).

  Laser light is emitted from a semiconductor laser, and the surfaces of the photoreceptors 1Y, 1M, 1C, and 1K are scanned in the direction of the rotation axis of the photoreceptor by a polygonal polygonal mirror (polygon) that rotates at high speed.

  The latent image formed in this manner is developed with a developer composed of toner particles or a mixture of toner particles and carrier particles supplied on a developing sleeve which is a developer carrying member in the developing device 5, and toner can be transferred. A visual image is formed.

  At the time of developing the latent image, a voltage of an appropriate magnitude or an AC voltage between the exposed portion and the non-exposed portion of the photoreceptors 1Y, 1M, 1C, and 1K is applied from the voltage application mechanism (not shown) to the developing sleeve. A developing bias with superimposed is applied.

The toner images formed on the photoconductors 1Y, 1M, 1C, and 1K corresponding to the respective colors are transferred onto the intermediate transfer body 60 by the transfer device 6 and fed from the paper feed mechanism 200, such as paper. A toner image is transferred onto the medium.
At this time, it is preferable that a potential having a polarity opposite to the polarity of toner charging is applied to the transfer device 6 as a transfer bias. Thereafter, the intermediate transfer member 60 is separated from the photoreceptor, and a transfer image is obtained.
Further, the toner particles remaining on the photosensitive member are collected into a toner collecting chamber in the cleaning device 4 by a cleaning unit.

  As the image forming apparatus, an apparatus in which a plurality of the developing devices described above are arranged is used, and a plurality of toner images, which are sequentially produced by the plurality of developing devices, are sequentially transferred onto a transfer material, and then sent to a fixing mechanism to be heated. Even after a plurality of toner images prepared in the same manner are sequentially sequentially transferred onto an intermediate transfer member and then transferred to a recording medium such as paper, Similarly, a fixing device may be used.

  The charging device 3 is preferably a charging device arranged in contact with or close to the surface of the photoreceptor, and a discharge wire is used. This makes it possible to significantly suppress the amount of ozone generated during charging as compared with a corona discharger called a so-called corotron or scorotron.

  In a charging device that charges such a charging member in contact with or close to the surface of the photoconductor, the electrical stress on the photoconductor tends to increase because the discharge is performed in the region near the surface of the photoconductor as described above. It is. However, by using the protective layer forming apparatus using the protective agent block of the present invention, it can be maintained for a long time without deteriorating the photoconductor, so that the fluctuation of the image over time and the fluctuation of the image due to the use environment are greatly increased. It can be suppressed and stable image quality can be ensured.

  As described above, the image forming apparatus of the present invention has an excellent tolerance for fluctuations in the surface state of the photoreceptor, and has a structure in which fluctuations in charging performance to the photoreceptor are highly suppressed. By using in combination with toner, it is possible to stably form an extremely high quality image over a long period of time.

(Process cartridge)
The process cartridge of the present invention comprises at least a photosensitive member and the protective layer forming unit of the present invention, and further includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit and the like as necessary. It has other means.

  The process cartridge of the present invention can be detachably provided in various electrophotographic image forming apparatuses, and is preferably detachably provided in the above-described image forming apparatus of the present invention.

Here, FIG. 8 is a schematic diagram for explaining an outline of a configuration example of a process cartridge using the protective layer forming apparatus of the present invention.
The process cartridge is provided with a protective layer forming apparatus 2 disposed opposite to the photosensitive drum 1 as a photosensitive member. The protective layer forming apparatus 2 includes a protective agent block 21, a protective agent supply unit 22, a pressing unit 23, a thinning unit 24, and the like. Composed.

Further, the photoreceptor 1 has a surface in which partially deteriorated protective agent, toner component, and the like remain after the transfer process, but the surface residue is removed by the cleaning unit 4 including the cleaning unit 41, the cleaning pressing mechanism 42, and the like. Cleaned and cleaned.
In FIG. 8, the cleaning means 4 is contacted at an angle similar to a so-called counter type (leading type).

The protective agent 21 is supplied from the protective agent supply means 22 to the surface of the photoreceptor from which the residual toner and the deteriorated protective agent have been removed by the cleaning means, and a thin film forming means 24 forms a film-like protective layer. Is done. At this time, the protective agent used in the present invention can stably and stably supply the necessary and sufficient amount to the surface of the photoreceptor, efficiently protecting the surface of the photoreceptor, and deterioration of the photoreceptor itself over a long period of time. Can be prevented.
In FIG. 8, the thinning means 24 is arranged in the trading direction, but may be arranged in the counter direction. In particular, when the linear velocity of the photosensitive member is increased to 180 mm / second or more, it is preferable to dispose the photosensitive member in the counter direction because the formation of the protective film becomes faster.

  The photosensitive member thus formed with the protective layer is charged, and then an electrostatic latent image is formed by exposure L such as a laser, developed by the developing device 5 to be visualized, and a transfer roller outside the process cartridge. 6 or the like.

  As described above, the process cartridge of the present invention has an excellent tolerance for fluctuations in the surface state of the photoreceptor, and has a configuration in which fluctuations in charging performance to the photoreceptor are highly suppressed. Can be formed stably over a long period of time.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Production Example 1)
-Production of photoreceptor 1-
An undercoat layer, a charge generation layer, a charge transport layer, and a protective layer were applied in this order on an aluminum drum (conductive support) having a diameter of 40 mm, and then dried, and an undercoat layer having a thickness of 4.2 μm and a thickness of 0 A photoreceptor comprising a .15 μm charge generation layer, a 21 μm charge transport layer, and a 4.6 μm protective layer was prepared. In addition, the coating of the protective layer was performed by a spray method, and the others were performed by a dip coating method.
[Coating liquid for undercoat layer]
・ Alkyd resin (Beckosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.) ... 6 parts by mass Melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)・ 4 parts by mass ・ Titanium oxide: 40 parts by mass ・ Methyl ethyl ketone: 200 parts by mass

[Coating liquid for charge generation layer]
-Y-type oxo titanyl phthalocyanine pigment-2 parts by mass-Polyvinyl butyral (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)-0.2 parts by mass-Tetrahydrofuran-50 parts by mass

[Coating liquid for charge transport layer]
-Bisphenol A type polycarbonate (manufactured by Teijin Ltd., Panlite K1300) ... 10 parts by mass-Low molecular charge transport material represented by the following structural formula: 10 parts by mass
・ Methylene chloride: 100 parts by mass

[Protective layer coating solution]
Polycarbonate: 10 parts by mass Low molecular charge transport material represented by the above structural formula: 7 parts by mass Alumina fine particles (center particle size: 0.30 μm): 6 parts by mass Dispersing aid ( BYK-P104 manufactured by Big Chemie Japan Co., Ltd. 0.08 parts by mass Tetrahydrofuran 700 parts by mass Cyclohexanone 200 parts by mass

(Production Example 2)
-Production of photoreceptor 2-
Production Example 1 except that 6 parts by mass of alumina fine particles (center particle size: 0.30 μm) in the protective layer coating solution was changed to 6.1 masses by alumina fine particles (center particle diameter: 0.33 μm). In the same manner as in Example 1, a photoreceptor 2 was produced.

(Comparative Example 1)
-Production of protective agent block 1-
Zinc stearate was heated to 145 ° C. and melted, and the molten zinc stearate was poured into an aluminum mold heated to 145 ° C. Thereafter, the mold was moved to a constant temperature bath having an air temperature of 25 ° C., and the protective agent block 1 having a size of 12 mm × 8 mm × length 350 mm was produced by turning off the heating and cooling.
When the produced protective agent block 1 was taken out of the mold, the protective agent block was bent and could not be mounted on the protective layer forming apparatus.

(Comparative Example 2)
-Production of protective agent block 2-
Zinc stearate was heated to 145 ° C. and melted, and the molten zinc stearate was poured into an aluminum mold heated to 145 ° C. Thereafter, the mold temperature was cooled to 125 ° C. at a cooling rate of 10 ° C./min, and maintained at 125 ° C. for 5 minutes. Then, it cooled to 90 degreeC with the cooling rate of 2.5 degreeC / min, and also stopped heating, and produced the protective agent block 2 of 12 mm x 8 mm x length 350mm by cooling to room temperature.
As shown in FIG. 9, the vicinity of the center in the longitudinal direction of the produced protective agent block 2 was cut out with a yarn saw so as to be 4 mm × 8 mm × 10 mm. A groove was formed by a cutter knife next to the cut out protective agent block, the groove was turned upward, placed on a convex base, and the protective agent block was broken by applying force from above. The cross section of the protective agent block was observed with a scanning electron microscope (SEM) at magnifications of 500 times and 5,000 times on the split surface that was removed from the groove made by the cutter. On the split surface, fine stearic acid particles of 0.1 μm to 0.3 μm had a fused shape (no flat piece was seen).

Example 1
-Protective agent block 3-
Stearic acid and palmitic acid are mixed in a ratio of (stearic acid: palmitic acid = 65: 35 (mass ratio)), zinc hydroxide is mixed and melt-reacted in the mixture, dried, and zinc stearate and zinc palmitate are mixed. Were produced (particle size 11 μm to 23 μm).
Part of the produced particles are dissolved in a hydrochloric acid-methanol solution and heated to 80 ° C. to methylate stearic acid and palmitic acid, and the contents of stearic acid and palmitic acid are measured by gas chromatography. When converted to the ratio of zinc palmitate, it was 64:34 (mass ratio).
The prepared zinc stearate-zinc palmitate particles were heated to 145 ° C. and melted, and the molten metal soap was poured into an aluminum mold heated to 145 ° C. While applying ultrasonic waves to the mold, it was cooled to 125 ° C. at a cooling rate of 10 ° C./min, and cooled to 100 ° C. at a cooling rate of 5 ° C./min. The mold was heated to 125 ° C. at a temperature rising rate of 10 ° C./min and maintained at 125 ° C. for 2 minutes. After cooling to 103 ° C. at a cooling rate of 2 ° C./min, the ultrasonic wave is stopped, cooling to 70 ° C. is performed at a rate of 20 ° C./min, heating is stopped, and cooling to room temperature is performed. A protective agent block 3 having a length of 350 mm was produced.
The produced protective agent block 3 was split in the same manner as in Comparative Example 2, and the split surface was observed with a scanning electron microscope (SEM) at magnifications of 500 and 5,000. The entire split surface had flat fragments with an average thickness of 1.1 μm. The surface of the flat piece is a homogeneous surface and fine particles cannot be observed, but the flat piece has a shape in which particles having an average particle diameter of 0.9 μm are fused.

(Comparative Example 3)
-Production of protective agent block 4-
Palmitic acid was heated to 140 ° C. and melted, and molten zinc stearate was poured into an aluminum mold heated to 140 ° C. Thereafter, the mold temperature was cooled to 123 ° C. at a cooling rate of 10 ° C./min, and maintained at 123 ° C. for 5 minutes. Then, it cooled to 85 degreeC with the cooling rate of 2.5 degreeC / min, and also stopped heating, and produced the protective agent block 4 of 12 mm x 8 mm x length 350mm by cooling to room temperature.
The produced protective agent block 4 was split in the same manner as in Comparative Example 2, and the split surface was observed with a scanning electron microscope (SEM) at magnifications of 500 and 5,000. On the split surface, fine palmitic acid particles having a size of 0.1 to 0.3 μm were fused (no flat fragments were seen).

(Example 2)
-Production of protective agent block 5-
Zinc stearate and zinc palmitate were mixed at a ratio of (zinc stearate: zinc palmitate = 50: 50 (mass ratio)) and heated to 145 ° C. to melt. The molten metal soap was poured into an aluminum mold heated to 145 ° C. While applying ultrasonic waves to the mold, it was cooled to 125 ° C. at a cooling rate of 10 ° C./min, and cooled to 100 ° C. at a cooling rate of 5 ° C./min. The mold was heated to 125 ° C. at a rate of temperature increase of 10 ° C./min and held at 125 ° C. for 2 minutes. After cooling to 103 ° C. at a cooling rate of 2 ° C./min, the ultrasonic wave is stopped, cooling to 70 ° C. is performed at a rate of 20 ° C./min, heating is stopped, and cooling to room temperature is performed. A protective agent block 5 having a length of 350 mm was produced.
The produced protective agent block 5 was split in the same manner as in Comparative Example 2, and the split surface was observed with a scanning electron microscope (SEM) at magnifications of 500 times and 5000 times. The entire split surface had flat fragments with an average thickness of 1.0 μm. The surface of the flat piece is a homogeneous surface and fine particles cannot be observed, but the flat piece has a shape in which particles having an average particle diameter of 0.8 μm are fused.

(Comparative Example 4)
-Production of protective agent block 6-
In the protective agent block 4 of the comparative example 3, it was the same as that of the comparative example 3 except having added 3.5 mass% boron nitride (average primary particle size: 0.3 micrometer) with respect to the mass of zinc stearate. A protective agent block 6 was produced.
The produced protective agent block 6 was split in the same manner as in Comparative Example 2, and the split surface was observed with a scanning electron microscope (SEM) at magnifications of 500 times and 5,000 times. On the split surface, fine stearic acid particles of 0.1 to 0.3 μm were fused (no flat piece was seen).

(Example 3)
-Production of protective agent block 7-
In the protective agent block 3 of Example 1, the same procedure as in Example 1 was conducted except that 3.5% by mass of boron nitride (average primary particle size: 0.3 μm) was added to the mass of zinc stearate. A protective agent block 7 was prepared.
The produced protective agent block 7 was split in the same manner as in Comparative Example 2, and the split surface was observed with a scanning electron microscope (SEM) at magnifications of 500 times and 5,000 times. The entire split surface had flat fragments with an average thickness of 1.1 μm. The surface of the flat piece is a homogeneous surface and fine particles cannot be observed, but the flat piece has a shape in which particles having an average particle diameter of 0.9 μm are fused.

(Comparative Example 5 and Examples 4 to 8)
-Production of protective agent blocks 8-13-
Zinc stearate and zinc palmitate shown in Table 1 were mixed at a predetermined ratio, and protective agent blocks 8 to 13 of 9 mm × 8 mm × 350 mm in length were produced under various cooling conditions.
The produced protective agent blocks 8 to 13 were divided in the same manner as in Comparative Example 2, and the split surface was observed with a scanning electron microscope (SEM) at magnifications of 500 times and 5,000 times. The entire split surface had flat fragments with an average thickness of 1.1 μm. The surface of the flat piece is a homogeneous surface and fine particles cannot be observed, but the flat piece has a shape in which particles having an average particle diameter of 0.9 μm are fused.

Example 9
A tandem type color image forming apparatus (image MP C3500) was modified, and a protective agent coating blade was arranged on the counter so as to have the configuration of FIG. 5, and the linear velocity of the photosensitive member was set to 290 mm / second. Further, the charging was modified by applying a DC voltage of −600 V and an AC voltage of an amplitude of 1.2 kV and a frequency of 2.1 kHz to the photosensitive member by a charging roller.
Four process cartridges were prepared using the photoreceptor 1 and the protective agent block 3 of Example 1, and mounted on a modified tandem type image forming apparatus. A total of 25,000 images of a test chart with an image density of 8% were formed on each of 5 sheets in an environment of 35% RH at 22 ° C. In other words, the image forming apparatus is started to form five images, the image forming apparatus is temporarily stopped, the operation is restarted to form five images, and a total of 25,000 images are formed. . Thereafter, yellow, cyan, magenta, and black halftone images were output, and each image was evaluated.
The image of the image forming apparatus using the protective agent block 3 of Example 1 was a halftone image of all colors, and a high quality image was obtained.

(Comparative Example 6)
In Example 9, except that the protective agent block 2 of Comparative Example 2 was used in place of the protective agent block 3, four process cartridges were produced in the same manner as in Example 9, and a modified tandem type image forming apparatus The image was formed, and each image was evaluated.
The image of the image forming apparatus using the protective agent block 2 of Comparative Example 2 is a half-tone image of cyan, magenta, and black, and a streak-like fine abnormal image is generated. In particular, magenta and black are clearly recognized abnormalities It was an image.

(Example 10)
The tandem type color image forming apparatus (image MP C3500) was modified, and a protective agent coating blade was arranged on the counter so as to have the configuration of FIG. 5, and the linear velocity of the photosensitive member was set to 170 mm / second. Further, the charging was modified by applying a DC voltage of −600 V and an AC voltage of an amplitude of 1.2 kV and a frequency of 1.5 kHz to the photosensitive member by a charging roller.
Four process cartridges were produced using the photoreceptor 1 and the protective agent block 5 of Example 2, and mounted on a modified tandem type image forming apparatus. A total of 20,000 images of a test chart having an image density of 12% were formed in 5 sheets under an environment of 20 ° C. and 45% RH.
Thereafter, yellow, cyan, magenta, and black halftone images were output, and each image was evaluated.
Although the yellow, cyan, and magenta halftone images produced using the protective agent block 5 of Example 2 had high image quality, the black halftone image was at an acceptable level, but when staring, streaky abnormal images were observed. Was slightly observed.

(Comparative Example 7)
In Example 10, except that the protective agent block 4 of Comparative Example 3 was used instead of the protective agent block 5, four process cartridges were produced in the same manner as in Example 10, and the modified tandem type image forming apparatus The image was formed, and each image was evaluated.
In the image of the image forming apparatus produced using the protective agent block 4 of Comparative Example 3, streak-like abnormal images were observed in any color image, and the level was unacceptable particularly in the black image.

(Example 11)
The tandem type color image forming apparatus (image MP C3500) is modified, the protective agent coating blade is arranged on the counter so as to have the configuration shown in FIG. 5, the photosensitive member linear velocity is set to 340 mm / second, and charging is performed by the charging roller. The image forming apparatus was manufactured by modifying the body so as to apply a DC voltage of -600 V and an AC voltage of amplitude of 1.2 kV and a frequency of 3.0 kHz.
Four process cartridges were prepared using the photoreceptor 1 and the protective agent block 5 of Example 2, and mounted in a modified tandem type image forming apparatus. A total of 25,000 images of a test chart having an image density of 12% were formed in 5 sheets each in an environment of 20 ° C. and 40% RH.
Thereafter, halftone images of yellow, cyan, magenta, and black were output, and each image was evaluated. As a result, the image using the protective agent block 5 of Example 2 was slightly streaked on the magenta and black images. Observed.

(Comparative Example 8)
In Example 11, except that the protective agent block 4 of Comparative Example 3 was used instead of the protective agent block 5, four process cartridges were produced in the same manner as in Example 11, and the tandem type image forming apparatus was modified. The image was formed, and each image was evaluated.
As for the image of the image forming apparatus produced using the protective agent block 4 of Comparative Example 3, streaky abnormal images were observed in all the images.

(Example 12)
The tandem type color image forming apparatus (image MP C3500) is modified, the protective agent coating blade is arranged on the counter so as to have the configuration of FIG. 5, the photosensitive member linear velocity is set to 220 mm / second, and the charging roller is applied to the photosensitive member. On the other hand, a modification was made so that a DC voltage of −600 V and an AC voltage with an amplitude of 1.25 kV and a frequency of 1.9 kHz were applied.
Four process cartridges were produced using the photoreceptor 2 and the protective agent block 7 of Example 3 and mounted on a modified tandem type image forming apparatus. A total of 15,000 images of a test chart having an image density of 5% were formed in 5 sheets each in an environment of 18 ° C. and 25% RH.
Thereafter, yellow, cyan, magenta, and black halftone images were output, and each image was evaluated.
As for the image using the protective agent block 7 of Example 3, a high-quality image was obtained for any image.

(Comparative Example 9)
In Example 12, except that the protective agent block 6 of Comparative Example 4 was used instead of the protective agent block 7, four process cartridges were produced in the same manner as in Example 12, and the modified tandem type image forming apparatus The image was formed, and each image was evaluated.
In the image using the protective agent block 6 of Comparative Example 4, an abnormal image having a partially low image density occurred in all the images.

(Examples 13 to 17 and Comparative Example 10)
The tandem type color image forming apparatus (image MP C3500) is modified, the protective agent coating blade is arranged on the counter so as to have the configuration of FIG. 5, the photosensitive member linear velocity is set to 220 mm / second, and the charging roller is applied to the photosensitive member. On the other hand, a modification was made so that a DC voltage of −600 V and an AC voltage of 1.9 kHz with an amplitude of 1.2 kV were applied.
Four process cartridges were prepared using the photoreceptor 2 and the protective agent blocks 8 to 13 and mounted on a modified tandem type image forming apparatus. A total of 30,000 images of a test chart having an image density of 5% were formed in a test chart of 5 sheets at 28 ° C. and 45% RH.
Thereafter, yellow, cyan, magenta, and black halftone images were output, and each image was evaluated.
In the image of the image forming apparatus using the protective agent block 8 of Comparative Example 5 in Comparative Example 10, a streaky abnormal image was seen in the black and magenta halftone images.
The images of the image forming apparatus using the protective agent blocks 9 to 12 of Examples 4 to 7 in Examples 13 to 16 were all halftone images of all colors, and high-quality images were obtained.
The image of the image forming apparatus using the protective agent block 13 of Example 8 in Example 17 was an image in an allowable range, but when a halftone image of cyan and black was observed with a magnifying glass, dots flowed. A spot was observed.

  The image forming apparatus provided with the protective layer forming apparatus of the present invention can protect the photoconductor even when the photoconductor linear speed is high, and does not generate black streaks due to the increase in the resistance of the charging roller. Since it can be formed, it is suitably used for an electrophotographic image forming method, an image forming apparatus, a process cartridge, and the like.

DESCRIPTION OF SYMBOLS 1 Photoconductor 1Y, 1M, 1C, 1K Photosensitive drum 2 Protective layer formation apparatus 3 Charging apparatus 4 Cleaning apparatus 5 Developing apparatus 6 Transfer apparatus 7 Recording medium 21 Protective agent block 22 Protective agent supply means 23 Pressing means 24 Thinning means 41 Cleaning means 42 Cleaning pressing mechanism 60 Intermediate transfer body 100 Image forming apparatus 200 Paper feed mechanism

Japanese Patent Publication No.51-22380 Japanese Patent Laid-Open No. 10-279998 JP 2005-275166 A JP 2008-224828 A

Claims (7)

It consists of a protective agent block containing a metal soap which is a mixture of zinc stearate and zinc palmitate , and the split surface obtained by dividing the protective agent block has a flat cross section with a thickness of 0.2 μm to 2 μm. And a photoreceptor protective agent.   The surface of a flat piece having a thickness of 0.2 μm to 2 μm is a homogeneous surface, and the inside of the flat piece is formed by fusing metal soap particles having an average particle diameter of 0.05 μm to 0.2 μm. 1. The protective agent for a photoreceptor according to 1. The protective agent for a photoreceptor according to claim 1, wherein the protective agent block contains boron nitride. A protective agent supplying means for supplying a protective agent for the photosensitive member to the surface of the photosensitive member, a pressing means for pressing the protective agent for the photosensitive member according to any one of claims 1 to 3 to the protective agent supplying means, and the protection A protective layer forming apparatus comprising: a thinning means for thinning a layer made of the protective agent for the photoreceptor supplied to the surface of the photoreceptor by the agent supply means. The protective layer forming apparatus according to claim 4, wherein the blade as the thinning means is in contact with the photoconductor in the counter direction. A process cartridge comprising at least a photosensitive member and a protective layer forming unit according to any one of claims 4 to 5, and detachable from an image forming apparatus main body. A photosensitive member; an electrostatic latent image forming unit that forms an electrostatic latent image on the photosensitive member; a developing unit that develops the electrostatic latent image with toner to form a visible image; A transfer means for transferring an image to a recording medium, a protective layer forming means according to any one of claims 4 to 5, and a fixing means for fixing the transferred image transferred to the recording medium. Image forming apparatus.