JP2006091047A - Image forming apparatus, process cartridge and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which stably keeps a lubricating effect of a lubricant coating and a protective function for charging, which gives high-quality images for a long time and which achieves a long life, and to provide a process cartridge and an image forming method. <P>SOLUTION: The image forming apparatus (1) has a photoreceptor (2), a charging roller (3), an exposure unit (4) and a development unit (5), in which a lubricant is supplied to the surface of the photoreceptor (2) by using a solid lubricant (500) and a fur brush (502). The lubricant has a lamellar structure and is applied to form a coating as layers of the lamellar structure on the surface of the photoreceptor (2). The process cartridge is constituted as freely detachable to the image forming apparatus, and the image forming method uses the image forming apparatus. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine and a printer, a process cartridge, and an image forming method.

  Currently, image forming processes using electrophotography are widely used in image apparatuses such as copying machines, printers, and facsimiles. In an electrophotographic image forming process, an electrostatic latent image corresponding to input image information is usually formed on the surface of a drum-like or endless belt-like image carrier that is continuously circulated, that is, an electrophotographic photosensitive member. The electrostatic latent image is developed into a toner image, and the toner image is further transferred onto a transfer material. In this method, in addition to the stability of the electrical characteristics of the photoconductor that is responsible for repeated image formation, the surface is kept as close to the initial stage as possible for as long as possible without being worn or damaged as much as possible. Is required.

  In the electrophotographic photosensitive member used in the apparatus, excess toner on the surface of the photosensitive member is removed by a cleaning unit prior to the next image forming process. Residual toner that has not been completely removed may form a firm film called filming on the surface of the photoreceptor even if it is in a very small amount. Incidentally, a small particle size toner having a high degree of circularity aimed at improving image quality, specifically a circularity of 0.96 or more, adjusted by a so-called polymerization method, is disadvantageous in terms of cleaning. There is a tendency, and the improvement is desired.

  As one of the techniques for improving the cleaning property, it has been conventionally performed to apply a lubricant to the surface of the photoreceptor to form a thin film of the lubricant. Known lubricants used in this case include waxes, fluorine resins (polytetrafluoroethylene, polyvinylidene fluoride, etc.), and zinc stearate fatty acid metal salts. It can be understood that the improvement in the cleaning property by the lubricant is because the removal of foreign matters such as toner and additives becomes easy by reducing the friction.

  By applying the lubricant, in addition to the improvement of the cleaning property and the effect of preventing filming as a result, the effect of suppressing the wear of the photoreceptor can be expected. The lubricant reduces mechanical hazards on the surface of the photoconductor and improves durability related to photoconductor wear.

  Recently, especially in color image equipment, an intermediate transfer member is often used between the photosensitive member and the transfer material. In this case, the situation where the intermediate transfer member is placed and the hazard to be received are the same as those of the photosensitive member. Has a lot in common. It is known that the life of the intermediate transfer member is also determined mainly by abrasion due to mechanical rubbing with a cleaning brush or a cleaning blade. It is applied to reduce the friction coefficient to reduce wear. In the following description, for the sake of convenience, an “electrophotographic photosensitive member” or simply an “photosensitive member” and an “image carrier” that sometimes includes an intermediate transfer member are represented.

  As described above, the application of a lubricant can now be positioned as one of the fundamental process technologies for an electrophotographic image forming apparatus. Reflecting this situation, various methods for controlling the application state of the lubricant have been proposed. In Patent Document 1 (Japanese Patent Laid-Open No. 9-62163), the pressure of the solid lubricant applied to the photoconductor or the rotation speed of the coating brush in contact with the solid lubricant is controlled according to the temperature environment. Patent Document 2 (Japanese Patent Laid-Open No. 2000-75752) defines the amount of lubricant applied per unit rotational speed of the photoreceptor. In Patent Document 3 (Japanese Patent Laid-Open No. 2002-244485), the number of rotations of the application brush is controlled in accordance with image formation information. In Patent Document 4 (Japanese Patent Application Laid-Open No. 2000-338733), the application amount of the lubricant and the charging potential are controlled based on the density detection result of the pattern image formed on the photoconductor. In Patent Document 5 (Japanese Patent Laid-Open No. 2003-330320), the amount of lubricant applied is controlled in accordance with various conditions such as the degree of wear of the cleaning blade, the number of images formed, the distance traveled by the photosensitive member, and the temperature of the blade. Yes.

  These lubricants are usually supplied to the surface of the photoreceptor in a powder form in small amounts. As its specific method, as disclosed in Patent Document 6 (Japanese Patent Laid-Open No. 2000-162881), a method of scraping off and applying a solid molded lubricant on a block by an application means such as a brush, As disclosed in Patent Document 7 (Japanese Patent No. 2859646), there is a method of externally adding to toner and supplying it to a photoreceptor.

JP-A-9-62163 JP 2000-75752 A JP 2002-244485 A JP 2000-338733 A JP 2003-330320 A JP 2000-162881 A Japanese Patent No. 2859646

  However, the technique of applying the lubricant in the image forming apparatus is not a complete technique, and many insufficiencies are unavoidable. The reason for this is that little has been elucidated about the microscopic actual state of the lubricant coating alteration process and lubricant film formation process due to physical and chemical hazards.

  The charging process that takes place prior to the formation of an electrostatic latent image on the surface of the photoconductor is one of the main causes of physical and chemical hazards that the photoconductor surface is subjected to. Similar impacts. Particularly recently, instead of the conventional corona charging method, contact or charging of the surface of the photosensitive member by bringing a charging member such as a roller, brush, blade, etc. into contact with or close to the photosensitive member due to the advantage of low discharge products and low power. Although the proximity charging method is becoming mainstream, it is known that the hazard to the photoconductor is larger than that of the conventional method. Furthermore, an AC voltage superposition charging method in which an alternating current voltage is superimposed on a direct current voltage, which is proposed in order to avoid poor charging uniformity due to discharge unevenness, which is a relative disadvantage of the contact or proximity charging method (for example, Japanese Patent Laid-Open No. Hei 5). In the case of Japanese Patent No. -150564, the hazard to the photosensitive member is further increased.

  Therefore, in order to fully exhibit the function as a lubricant, first, the lubricant application method should be determined in consideration of the influence of charging. However, there are no known examples and disclosed examples so far. Furthermore, in the first place, the lubricant coating can be determined by a microstructural analysis in view of the film thickness scale, but there are no known examples or disclosed examples based on such technical knowledge. Generally speaking, although individual and partial improvements have been attempted mainly under macro matching conditions, this is not a solution that goes into micro-phenomena including physical property changes, but functional stability and sustainability. There was a problem.

  The present invention has been made in view of the above-described current situation of applying lubricant to a photoreceptor, and its purpose is to clarify the desirable mode of a lubricant film based on the knowledge of microstructural analysis. Thus, the apparatus has a stable lubricant coating device that can realize such a lubricant coating mode, and the lubricating effect of the lubricant coating and the protective function against charging are stably maintained, and a high-quality image can be obtained over a long period of time. Another object of the present invention is to provide a novel image forming apparatus, a process cartridge, and an image forming method that can achieve a long life.

According to a first aspect of the present invention, there is provided at least an image carrier, a charging member disposed in contact with or close to the image carrier, and a charging unit that charges the image carrier by applying a voltage to the charging member. And latent image forming means for forming an electrostatic latent image on the surface of the image carrier charged by the charging means, and development for attaching toner to the image portion of the electrostatic latent image formed by the latent image forming means. And the image forming apparatus further comprises a lubricant supply device for supplying a lubricant to the surface of the image carrier, wherein the lubricant is a lubricant having a lamellar structure, and In the image forming apparatus, the lubricant is formed on the surface of the image carrier as a lamellar laminate.
The invention according to claim 2 is characterized in that the wear of the lubricant caused by the operation of the image forming apparatus and the supply of the lubricant by the lubricant supply device are substantially in an equilibrium state. An image forming apparatus.
A third aspect of the present invention is the image forming apparatus according to the second aspect, wherein the amplitude distribution curve on the surface of the film has a plurality of maximum values when the surface of the image carrier is used as a reference plane.
According to a fourth aspect of the present invention, the lubricant supply device includes an application member that applies a lubricant to the surface of the image carrier and a leveling member that makes the lubricant applied to the image carrier uniform. The image forming apparatus according to claim 3.
The invention according to claim 5 is the image forming apparatus according to claim 4, wherein the lubricant is a fatty acid metal salt.
The invention according to claim 6 is that the fatty acid in the fatty acid metal salt contains at least one fatty acid selected from the group consisting of stearic acid, palmitic acid, myristic acid and oleic acid, and the metal is zinc, aluminum 6. The image forming apparatus according to claim 5, further comprising at least one metal selected from the group consisting of calcium, magnesium and lithium.
A seventh aspect of the present invention is the image forming apparatus according to the sixth aspect, wherein the fatty acid metal salt is mounted in the lubricant supply device as a solid fatty acid metal salt solidified.
The invention according to claim 8 is the image forming apparatus according to claim 7, wherein the solid fatty acid metal salt is zinc stearate.
The invention according to claim 9 is characterized in that the solid fatty acid metal salt also serves as an application member and supplies the lubricant by bringing the solid fatty acid metal salt into contact with the image carrier. This is an image forming apparatus.
A tenth aspect of the present invention is the image forming apparatus according to the fourth aspect, wherein a fur brush is used as the application member.
An eleventh aspect of the present invention is the image forming apparatus according to any one of the first to tenth aspects, wherein the toner has a circularity of 0.96 or more.
The invention of claim 12 is the image forming apparatus according to any one of claims 1 to 11, wherein the image carrier includes amorphous silicon.
The invention according to claim 13 is the image forming apparatus according to any one of claims 1 to 11, wherein the image carrier is OPC (organic photoreceptor) in which a filler is dispersed and strengthened on a surface layer. is there.
A fourteenth aspect of the present invention is the image forming apparatus according to any one of the first to eleventh aspects, wherein the image carrier is an OPC using a crosslinkable charge transport material.
The invention according to claim 15 is the image forming apparatus according to any one of claims 1 to 14, wherein the image forming apparatus is an image forming apparatus that forms an image by superposing toner a plurality of times. It is.
According to a sixteenth aspect of the present invention, there is provided a process cartridge comprising at least the lubricant supply device according to the first aspect, a charging unit, and an image carrier, wherein the process cartridge is configured to be detachable from the main body of the image forming apparatus.
A seventeenth aspect of the present invention is the process cartridge according to the sixteenth aspect, further comprising the charging member according to the first aspect.
The invention according to claim 18 is an image forming method comprising the steps of charging the surface of the image carrier, forming an electrostatic latent image, and attaching toner to the image portion of the electrostatic latent image. The lubricant is supplied by a lubricant supply device, the lubricant is a lubricant having a lamellar structure, and the lubricant is coated on the surface of the image carrier as a lamellar structure laminate. This is an image forming method.

  According to the present invention, the lubricating effect of the lubricant film and the protection function against charging are stably maintained, a high-quality image can be obtained over a long period of time, and a long life can be achieved, A process cartridge and an image forming method are provided.

The present invention will be further described below.
First, the knowledge relating to the microscopic actual state of the lubricant (actually using the general microscopic features up to the nm scale), which is the basis of the present invention, will be described.

  When a solid lubricant film is formed by some means, even a seemingly homogeneous film does not necessarily have a homogeneous thin film structure in a microscopic sense. For example, a fluorine-based polymer, which is a typical material of a polymer-based lubricant, covers a material to be adhered in the form of a spider web frayed with fine fibers having a thickness of several tens of nm (“Journal of Japanese Imaging Society 146, Examples of physical property imaging by AFM in “p39” and a comparative example will be described later). Although the fluorine-based polymer is excellent in low friction, the coating effect (hazard replacement effect) and durability do not necessarily satisfy the design requirements.

  On the other hand, some fatty acid metal salts form a stable coating with a high coating effect in the form of a laminate having a lamellar structure under a certain controlled system. The present inventors have found that this aspect is extremely desirable as a film aspect of a support of an image forming apparatus, and achieved the present invention. It is not simply a technology that is within the scope of the prior art of using a compound that can take a lamellar structure as a solid lubricant. Specifically, a laminate having a stable lamellar structure in an image forming apparatus means that the wear caused by the hazard of the lubricant caused by the operation of the image forming apparatus and the supply of the lubricant by the lubricant supply device are almost balanced. The structure is such that the lamella layer is geometrically substantially parallel to the surface of the image carrier, and a plurality of lamella layers are laminated.

  The fatty acid metal salt that can take such an embodiment contains at least one fatty acid selected from stearic acid, palmitic acid, myristic acid, and oleic acid, and is selected from zinc, aluminum, calcium, magnesium, and lithium. Examples include fatty acid metal salts containing at least one metal. Among them, zinc stearate is the most preferable material in terms of cost, quality stability, and reliability because it is produced on an industrial scale and has been used in many fields. However, the higher fatty acid metal salt generally used industrially is not a single compound composition of its name, but includes other fatty acid metal salts, metal oxides, and free fatty acids that are more or less similar. Fatty acid metal salts are no exception.

  The laminated body of the lamellar layer will be described in detail according to observation examples, taking as an example solid zinc stearate (which contains a similar amount of fatty acid metal and other components, particularly zinc palmitate and zinc oxide).

It is known that higher fatty acids and metal salts thereof can have a lamellar structure. The lamellar structure is a structure in which layers formed by regularly folding molecules are stacked and arranged, and since observation with an optical microscope is generally difficult, it has been confirmed mainly by an electron microscope. However, it is difficult to obtain quantitative data with an electron microscope. As a preliminary observation, the inventors observed the cracks in the fractured portion of the stearate microcrystal piece with an atomic force microscope (AFM) (FIG. 1), and the thickness of the lamellar layer was about 4 to 6 nm. It was confirmed. In FIG. 1, the X axis and the Y axis are in a range of about 6 μm square, and the height (Z axis) is emphasized 10 times and displayed in three dimensions (bird's eye view). A number of bent parallel curves that look like grain or contour lines are stearic acid lamellar structures, and the thickness of the lamellar layer can be measured to 4 to 6 nm from the interval of the steps. Next, a small amount of fine zinc stearate powder released from the molded zinc stearate block was applied to the surface of the organic photoreceptor (OPC) through a rubbing brush, and the adhesion state was observed with AFM (FIG. 2). ). The fine powder of zinc stearate is a so-called leaf-like flake having a size of 100 to 200 nm, the thickness is about 5 nm, and it was found to be a unit lamellar layer (in the following examples, the equivalent zinc stearate as a material) Using a molding bar). Observation and quantitative analysis by AFM are extremely effective for the development of solid lubricants, which is the technical gist of the present invention.
Note that the AFM images of the reference, examples, and comparative examples in the present description appropriately select and use stereoscopic images, such as a bird's-eye view, a height image, and a phase image, which are considered suitable for the description. The bird's eye view and the height image are displayed brighter as the height is higher, but the display of the density scale bar is omitted because the purpose is to display the form. Even in the Phase Image, the mode of distribution is obvious from sufficient contrast, and thus the display of the angle scale bar is omitted. However, the plane direction and the height scale are shown in the figure. These AFM image display styles and some applications of AFM observation represented by Phase Imaging are widely known to engineers and researchers in related fields. For example, applications of Digital Instruments Many specific examples are disclosed in notes and the like.

The lamellar layer will be further explained based on experiments and observations with zinc stearate. The image carrier used is OPC having a surface layer of a 23 μm layer made of aluminum as a base and a charge transfer agent mixed in polycarbonate.
A trace amount of a fatty acid metal salt (hereinafter sometimes simply referred to as a lubricant) adhering to a sufficiently smooth solid surface cannot yet form a film quantitatively. Naturally, if the supply of lubricant continues, the amount of adhesion will increase, but in other words, it will lightly accumulate, and the lubricant will not immediately form a coating (FIG. 2). However, when a certain level of rubbing and pressure contact is applied to the lubricant adhering portion at an appropriate timing, the lubricant flakes are melted in the lateral direction to form a single lamellar layer film (FIG. 3). . When the supply of lubricant and rubbing / pressure welding are repeated alternately, the lubricant eventually grows in the lateral and height directions as a laminate of lamellar layers until it completely covers the adherend surface (Fig. 4, described later as an example). In such a form, the lamellar laminate can stably and fully function as a lubricating layer and a protective layer, particularly when the highest flat portion has an area ratio of 10% or more, more preferably 50% or more. . The highest flat portion is the height of the peak closest to (0) above the vertical axis (Depth) of the amplitude distribution curve (ADC) in the explanation of the drawings regarding each AFM observation image. Contact from the outside is first supported by this flat portion. When the surface uneven layer portion of the solid lubricant is composed of n lamellar layers, the ADC has n peaks, and the solid lubricant layer has the most ideal unevenness of one lamellar layer (n = 2). The area ratio of the highest flat part often exceeds 50%. This situation is created in FIG. FIG. 5 (b) The area ratio of the peak near Depth 4.5 μm, which is the highest flat part of the lower right / left ADC, is approximately 60% when viewed from the cumulative frequency represented as the right Bearing area. . The number of terraces is preferably 5 or less (FIG. 6) in view of the stability of the lubricating layer, but the ADC height distribution is not necessarily divided equally by the number of steps (terrace), and in fact the highest flat part. A preferable effect is obtained when the area ratio is 10% or more.

  In the image forming apparatus of the present invention, how to supply and press the lubricant may be determined by overall and comprehensive judgment in design. For example, the lubricant may be supplied using a fur brush. However, instead of this, a method in which the solid lubricant also serves as an application member and directly contacts the image carrier may be used. The image forming apparatus can be provided with a leveling member that uniformly applies the applied lubricant. The leveling member is not limited to a blade, and may be a rubber roller made of an elastic material. It is preferable to use the blade as a leveling member because it simplifies the layout. Blade-shaped leveling members that are also used as cleaning members are natural rubber, synthetic natural rubber, styrene rubber, nitrile rubber, butadiene rubber, chloroprene rubber, urethane rubber, silicon rubber, ethylene / propylene rubber, butyl rubber, fluoro rubber, acrylic Made of rubber, polysulfide rubber, chlorosulfonated polyethylene, etc., especially urethane rubber (polyurethane elastomer) is the most suitable material because of its tensile strength, impact resilience, abrasion resistance, flex resistance and ozone resistance. is there. The basic characteristic values of the rubber member are as follows: Hardness (JIS A scale); 40-100, Young's modulus: 4-10 MPa, 100% modulus; 2-5 MPa, rebound resilience: 20-80%. The blade contact pressure is preferably in the range of 120 to 250 mN / cm. In an example described later, a blade made of polyurethane elastomer having a hardness of 70, Young's modulus: 6.6 MPa, 100% modulus; 3.2 MPa, rebound resilience: 40% is used at a contact pressure of 200 mN / cm. . According to such a configuration of the apparatus, the laminated body having the lamellar structure according to the present invention can be formed on the surface of the image carrier. Further, by changing the above conditions, the balance between the supply of the lubricant and the wear of the image carrier due to the hazard can be arbitrarily changed.

  As described above, the lubricant coating is subject to a hazard due to electrification in the usage situation of the device, but the physical property alteration due to the charging of the fatty acid metal salt and its mechanism have not been clarified in the practical technical field. It was. However, the inventors of the present invention have found that fatty acid metal salts are fragmented by cutting off molecules by the energy of discharge in analysis such as XPS (X-ray photoelectron analysis), TOS-SIMS (time-of-flight mass spectrometry), and AFM ( Fragmentation) We confirmed the phenomenon of dissipating into free space. If the time scale is ignored, the alteration of the fatty acid metal salt due to the charging hazard is similar to the weathering of the exposed rock surface, but the “weathering” of the fatty acid metal salt proceeds in units of seconds under normal charging conditions. As will be shown in a later example, the present invention considers the speed of such alteration.

Next, a method for evaluating the form of the lubricant film according to the present invention will be described.
There are many evaluation methods for roughness or unevenness of a surface which is regarded as a plane on average at least locally. For example, JIS B0601-1994 defines roughness shape parameters such as arithmetic average roughness (Ra), maximum height (Rv), ten-point average roughness (Rz), and uneven average interval (Sm). In addition, there are roughness evaluation parameters such as the root mean square roughness (RMS), the average unevenness height (Rc), the average peak height (Rpm), and each of these parameters, in particular, the function of the workpiece surface, that is, Attention is appropriately paid in relation to the density, frictional force, adhesion, gloss, and the like. The present inventors have obtained the knowledge that the amplitude distribution curve (ADC) is the most reasonable as the roughness evaluation parameter of the lubricant film. Such knowledge also forms the technical point of the present invention.

  The amplitude distribution curve (ADC) is a curve representing the distribution of height, and is based on a plane that can be regarded as a plane on average (in the present invention, two-dimensional unevenness is a problem), and is equidistantly parallel to it. It is the curve which plotted the frequency of the height which exists in two divided | segmented parallel surfaces with respect to height. The cumulative frequency distribution (integration) from the higher side (upper side) of this curve indicates the transition of the load accompanying the progress of cutting in cutting or the like, and is therefore referred to as a load curve (BAC; Bearing Area Curve). However, ADC and BAC are theoretically equivalent as information, and in the present invention, description will be made mainly with ADC. Incidentally, in the present invention, the reference surface of the ADC may be a surface in which the surface of the image carrier on which the lubricant is formed is regarded as an approximately flat surface. That is, the distribution curve in the present invention means an amplitude distribution curve of the relative surface height when the surface of the image carrier is viewed as a reference plane. The concept of ADC and BAC is shown in FIG. ADC and BAC can be derived from the cross-sectional waveform of the coating.

Taking a lubricant coating as an example, typical types of amplitude distribution are illustrated by AFM observation and metric analysis. Some of them are also examples related to later examples and comparative examples.
First, a method for displaying an AFM observation result will be described.
5, 6, 8, 9, 10, and 11 (a) and FIGS. 1, 12, and 13 are 3D (stereoscopic) displays also called bird's-eye views of AFM observation images. The scale of X, Y) and height (Z) is shown as the length of one division (div) in the figure at the lower right of the 3D display diagram (where X and Y are equal scales). When the scales of X (= Y) and Z are different (all except for FIG. 8A), the height (Z) is highlighted in the reciprocal multiple of X / Z. 5, 6, 8, 9, 10, and 11 (b), the upper right portion indicates the unevenness of the sample in a cross-sectional shape along the straight line in the left plan view of the observation unit. The cutting line can be chosen arbitrarily, but it should be chosen so that it passes through a typical part. The lower right and left of (b) are histograms displaying the frequency of the height of the entire observation surface of the sample, and the cross-sectional shape along the straight line, as a percentage. These correspond to the amplitude distribution curve (ADC) described above. To do. Note that the vertical axis on the paper surface of the ADC is displayed in Depth with the maximum height being 0 because it is displayed based on the expansion and contraction of the Z-axis of the scanner located above the sample. Since the unevenness is a height difference, the positive and negative directions of the axis and the zero point are not a problem. The lower right and right of (b) are the load curve (BAC) described above with respect to the function obtained by integrating the ADC from above, that is, the cumulative frequency distribution of the height distribution. In other words, referring again to the explanatory diagram of FIG. 7, the upper right, lower right / left, lower right / right of FIG. 5, FIG. 6, FIG. 8, FIG. 9, FIG. Corresponds to a cross-sectional waveform, an amplitude distribution curve (ADC), and a load curve (BAC) (however, the actually measured ADC is a two-dimensional height distribution). The unevenness state can be read from the number of substantial peaks (ignoring fine unevenness) of the amplitude distribution curve. Further, the area ratio of the highest flat portion described later can be read from the value of “Bearing Area” (relative cumulative frequency of the histogram) of the “shoulder” on the higher side of the load curve.

  FIG. 8 is an image of a typical rough surface observed by AFM, and the amplitude distribution curve is generally a bell-shaped distribution (Gaussian distribution) having an average height as a peak as shown in FIG. 8B. This example was selected as a comparative example in which the pitch scale is close to the lubricant which is a problem in the present invention on the surface of the TiO particle dispersion film. In the case of a TiO particle dispersion film, there is no terrace-like flat portion. Next, analysis examples in the case where the lubricant film has a typical lamellar laminated structure are shown in FIGS. The surface irregularity shape of a typical lamellar laminate is a terrace structure with discrete heights at several steps of the lamellar layer interval, and its cross section is at least partially stepped up and down (FIG. 6 ( b)), a rectangular wave shape (FIG. 4B) which repeats the unevenness of the lamellar single layer. In these cases, the amplitude distribution curve characteristically has a number of peaks, that is, at least two peaks, each peak indicating the terrace area ratio at that height. One step is a lamellar unit layer, and from a macro viewpoint, the preferred coating form of the solid lubricant that forms the lamellar layer is that several layers of plate-like paving stones are laid down on the surface of the ground. It can be said that it is covered in parallel.

  FIG. 14 shows an example of an image forming apparatus to which the present invention is applied. In FIG. 14, an image forming apparatus (1) houses a photoreceptor (2) as an image carrier that is driven to rotate clockwise in FIG. 14, and a charging roller (2) is placed around the photoreceptor (2). 3), an exposure unit (4), a developing unit (5), a transfer unit (6), a photoconductor cleaning unit (13), and a charge eliminating unit (8), and a transfer unit (6) and a photoconductor cleaning unit (13). ) Is provided with a lubricant supply device comprising a solid lubricant (500) and a fur brush (502).

  Although not shown, the image forming apparatus (1) includes a paper feeding cassette that stores a plurality of recording papers. The recording paper in the paper feeding cassette is paired with a pair of registration rollers (not shown) by a paper feeding roller (not shown). After the timing is adjusted, the sheet is sent out between the transfer portion (6) and the photosensitive member (2).

  The image forming apparatus (1) rotates the photosensitive member (2) in the clockwise direction in FIG. 14 and uniformly charges the photosensitive member (2) with the charging roller (3) serving as a charging unit and a charging member. The exposure unit (4) irradiates a laser modulated with image data to form an electrostatic latent image on the surface of the photosensitive member (2), and the developing unit (5) is formed on the image portion on which the electrostatic latent image is formed. Develop with toner attached. In the image forming apparatus (1), the photosensitive member (2) on which the toner image is formed by attaching the toner in the developing unit (5) is transferred between the photosensitive member (2) and the transferring unit (6) by the transfer unit (6). The image is transferred onto the recording paper conveyed in between, and the recording paper on which the toner image is transferred is conveyed to the fixing unit. The fixing unit includes a fixing roller heated to a predetermined fixing temperature by a built-in heater and a pressure roller pressed against the fixing roller with a predetermined pressure, and heats the recording paper conveyed from the transfer unit (6). After pressurizing to fix the toner image on the recording paper on the recording paper, it is discharged onto a paper discharge tray (not shown).

  The image forming apparatus (1) further rotates the photosensitive member (2) on which the toner image is transferred to the recording paper by the transfer unit (6), and removes the toner remaining on the surface of the image carrier by the photosensitive member cleaning unit (13). After removing by scraping with a blade, the charge is removed by the charge removal section (8). The image forming apparatus (1) performs the next image formation in the same manner as described above after uniformly charging the photoconductor (2) neutralized by the neutralization unit (8) by the charging unit (3). The photosensitive member cleaning unit (13) is not limited to the one that scrapes off the residual toner on the photosensitive member (2) with a blade, and for example, the residual toner on the photosensitive member (2) is scraped off with a fur brush. There may be. Then, the lamellar structure laminate of the present invention is provided by a lubricant supply device comprising a solid lubricant (500) and a fur brush (502) provided between the transfer section (6) and the photoreceptor cleaning section (13). Is provided on the photoreceptor (2) as described above.

  15A and 15B are diagrams for explaining another example of the image forming apparatus of the present invention. FIG. 15A is a tandem type full-color image forming apparatus, and FIG. 15B is a revolver type full-color image forming. Device.

In FIG. 15, the image forming apparatus (1) includes a photoconductor (2) that is driven to rotate clockwise in FIG. 15 in a main body housing (not shown), and around the photoconductor (2). There are a charging roller (3), an exposure unit (4), a development unit (5), an intermediate transfer unit (61), a paper transfer unit (7), and the like.
Although not shown, the image forming apparatus (1) includes a paper feeding cassette that stores a plurality of recording papers. The recording paper P in the paper feeding cassette is registered by a paper feeding roller (not shown). After the timing is adjusted in pairs, the sheet is fed between the intermediate transfer portion (61) and the paper transfer portion (7). Reference numeral 13 denotes a photosensitive member cleaning unit.

  The image forming apparatus (1) rotates the photosensitive member (2) in the clockwise direction in FIG. 15 to uniformly charge the photosensitive member (2) with the charging roller (3), and then the exposure unit (4). An electrostatic latent image is formed on the photosensitive member (2) by irradiating a laser modulated with image data, and toner is attached to the photosensitive member (2) on which the electrostatic latent image is formed by a developing unit (5). develop. In the image forming apparatus (1), a toner image obtained by adhering toner in the developing unit (5) is transferred from the photoreceptor (2) to the intermediate transfer member in the intermediate transfer unit (61). This is performed in four colors, CMYK, to form a color toner image. Although not shown in the drawing, a lubricant comprising a solid lubricant (500) and a fur brush (502) similar to that shown in FIG. 14 provided between the intermediate transfer portion (61) and the photosensitive member cleaning portion (13). As described above, the laminate having the lamellar structure of the present invention is provided on the photoreceptor (2) by the supply device.

  The revolver type full-color image forming apparatus shown in FIG. 15B sequentially develops a plurality of colors of toner on one image carrier by switching the operation of the developing device. The paper transfer unit (7) The color toner image on the intermediate transfer portion (62) is transferred to the recording paper P, and the recording paper P to which the toner image is transferred is conveyed to a fixing portion (not shown) to obtain a fixed image.

  On the other hand, the image forming apparatus (1) further rotates the photosensitive member (2) having the toner image transferred to the recording paper P by the intermediate transfer portion (62), and remains on the image carrier surface by the cleaning portion (13). After the toner is scraped off and removed by the blade, the charge is removed by the charge removal unit (8). The image forming apparatus (1) uniformly charges the photoreceptor (2) neutralized by the neutralization unit (8) with the charging roller (3), and then performs the next image formation as described above. The cleaning unit (13) is not limited to scraping off the residual toner on the photoconductor (2) with a blade. For example, the cleaning unit (13) scrapes off the residual toner on the photoconductor (2) with a fur brush. Also good. The charging roller (3) is a hard conductive roller disposed with a small gap with respect to the photoreceptor (2). Although not shown, a lubricant comprising a solid lubricant (500) and a fur brush (502) similar to that shown in FIG. 14 provided between the intermediate transfer portion (62) and the photosensitive member cleaning portion (13). As described above, the laminate having the lamellar structure of the present invention is provided on the photoreceptor (2) by the supply device.

  In the image forming apparatus (1) of FIG. 15, the intermediate transfer portions (61, 62) can also function as a smoothing member for the lubricant supplied by the fur brush as the application member.

  FIG. 16 is a schematic configuration diagram for explaining a layer configuration of an amorphous silicon photoreceptor suitable for the image forming apparatus of the present invention. A photoconductor 50 shown in FIG. 16A is provided with a photoconductive layer 52 made of a-Si: H and having photoconductivity on a support 51. A photoconductor 50 shown in FIG. 16B includes a photoconductive layer 52 made of a-Si: H and having photoconductivity, and an amorphous silicon surface layer 53 on a support 51. A photoconductor 50 shown in FIG. 16C is provided with a photoconductive layer 52 made of a-Si: H and having photoconductivity, and an amorphous silicon-based surface layer 53 on a support 51, and further supporting. An amorphous silicon based charge injection blocking layer 54 is provided on the body 501. In the photoconductor 50 shown in FIG. 16D, a photoconductive layer 52 is provided on a support 51. The photoconductive layer 52 comprises a charge generation layer 55 made of a-Si: H and a charge transport layer 56, and an amorphous silicon surface layer 53 is provided thereon.

  FIG. 17 is a view for explaining an example of the process cartridge of the present invention. In FIG. 17, (20) shows the entire process cartridge, (2) is a photoconductor, (3) is a charging roller, (5) is a developing unit, (13) is photoconductor cleaning means, and (500) is Solid lubricant (502) indicates a fur brush. The above-mentioned photoreceptor (2), charging device means (3), developing means (5), cleaning means (13), solid lubricant (500), and fur brush (502). The process cartridge (20) includes at least a lubricant supply device including a solid lubricant (500) and a fur brush (502), a charging roller (3), and a photoreceptor (2), and preferably includes a developing unit (5). The image forming apparatus main body is detachable.

Moreover, in this invention, an effect can further be heightened by employ | adopting the following form.
As the toner, a small particle size toner prepared by a polymerization method having a circularity of 0.96 or more is used, and exhibits an effective effect of preventing deterioration in cleaning properties.
-Image bearing members that have inherently high hardness and fine irregularities on the surface, that is, OPCs (organic photoreceptors) in which fillers are dispersed and strengthened on the surface layer, organic photoreceptors using cross-linked charge transport materials, and amorphous silicon Also in an image forming apparatus that employs a photoreceptor including the above, an excellent friction reducing effect is exhibited by forming a film of a lubricant on the surface of the photoreceptor as a lamellar laminate of the present invention.
・ In a full-color image forming apparatus that forms images by superposing multiple times of toner, the image quality is significantly reduced. , Effectively demonstrates the effect of suppressing.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples.
The following experiment was conducted using the image forming apparatus of FIG.
Prior to the experiment in the image forming apparatus, a stage moving type test apparatus was prepared in which the basic members of the image forming apparatus are linearly arranged and can be repeatedly operated. In this test apparatus, a plate-shaped photoconductor is used, but the test can be reproducibly performed under substantially the same physical conditions as the drum-type photoconductor used in the image forming apparatus. It is difficult to observe the drum-like member as it is with an atomic force microscope (it is difficult to hold the sample and fine background vibration cannot be avoided), and the sample is particularly broken in observing changes over time. Since it is not preferable, also in the observation of the following examples, an equivalent plate photoreceptor is appropriately observed instead of the drum-shaped photoreceptor.

Example 1
In FIG. 14, zinc stearate molded into a rod shape was used as the solid lubricant (500). A polyurethane elastomer blade having a hardness of 65 was used as the cleaning blade (13) serving as the photosensitive member cleaning portion. As the photoreceptor (2) as an image carrier, basically, an OPC which is a charge transfer layer having a film thickness of about 23 μm in which an aluminum drum is used as a base and an outermost layer is a polycarbonate and a charge transfer agent is mixed is used. . The charging roller has a metal cylinder as a core and a conductive layer on its surface. The conductive layer is held at the nearest portion with a space of 60 μm from the surface of the photoreceptor, and the core is charged for charging. A voltage obtained by superimposing an AC voltage on a DC voltage was applied at a timing controlled by gold.

According to conditions determined from preliminary experiments, application of lubricant with a brush and pressure contact treatment with an elastic blade (blade has hardness: 70, Young's modulus: 6.6 MPa, 100% modulus; 3.2 MPa, rebound resilience: 40%, A lubricant film made of polyurethane elastomer and having a contact pressure of 200 mN / cm was formed on the surface of the photoreceptor. The film thickness was determined by the X-ray reflectivity analysis method based on the simulation of Parratt. FIG. 4A shows an observation image of this lubricant film on the AFM. The shape analysis is shown in FIG. 4B (hereinafter, the AFM image of the lubricant film is displayed as a three-dimensional bird's-eye view (3D view), and the scale in the height direction is emphasized as appropriate).

  The photoreceptor was mounted as a photoreceptor (2) of the image forming apparatus (1). The peripheral speed of the photoconductor is 120 mm / s, the amount of biting of the fur brush (502) is about 1 mm, and the voltage applied to the charging roller (3) is AC component: Vpp 3.0 kV, frequency 1.3 kHz, DC component: − Repetition of the lubricant film after the run by repeating the run 500 times with the AC and DC superimposed voltage of 600 V, fixing the charging conditions and the rubbing conditions of the cleaning blade (13) and the fur brush, etc. Observed with an atomic force microscope. FIG. 9A shows an AFM observation image of the lubricant film after the run, and FIG.

(Example 2)
The fur brush (502) biting amount was about 2 mm, the contact pressure of the cleaning blade (13) was increased by 30%, and the other conditions were the same as in Example 1 and the same run was performed. FIG. 6A shows an AFM observation image of the lubricant film after the run, and FIG.

  9 and 6 are the same as those in FIG. That is, it is a laminate of lamellar layers having a thickness of about 4 to 5 nm and covers the surface of the photoreceptor without gaps with an uneven surface that is an integral multiple of the unit layer. Further, the amplitude distribution curve has a plurality of maximum values, and has one of the maximum values near the maximum height. The reason why the lubricant film appears to be the same as the initial state after long-term running is that the supply and leveling effect of the lubricant almost balanced and antagonized the wear due to friction and the wear / disappearance due to discharge during the run. The result is that the lubricant coating is stable in a dynamic sense and is in an ideal state. Specifically, the effect that a film without defects and gaps protects the surface of the photoconductor from hazards and the lubrication effect by the outermost surface with a flat and sufficient area ratio functions well and continuously. It is.

(Reference Example 1)
In order to see a change in excessive charging (actually discharging), the peripheral speed of the photoconductor of Example 1 was changed to 30 mm / s, and the other conditions were the same, and five runs were made. This condition corresponds to an acceleration condition in which the charging hazard has increased four times. FIG. 12 shows an AFM observation image of the lubricant film after the run. Ten more runs were performed without changing the conditions. FIG. 13 shows an AFM observation image of the lubricant film after the run.

  In FIG. 12, although the step structure of the lamellar layer is still visible, the surface is uniformly roughened and the small outermost lamellar layer disappears as if subjected to corrosion and weathering. In FIG. 13, the lamella structure itself is almost destroyed. These examples show that if the charge is excessive, the lubricant itself is deteriorated and dissipated, and the protection function against the charging hazard of the image carrier becomes ineffective. By the way, the lamellar laminate is only a few tens of nanometers thick, and these surface states are macroscopic observations as well as surfaces that are judged to be “highly smooth” in ordinary micron-scale observations. In the past, this difference has been overlooked without confirmation.

(Reference Example 2)
The contact pressure of the cleaning blade of Example 1 was reduced to one third, and the other conditions were the same, and five runs were performed. This condition corresponds to a condition where the leveling effect of the lubricant cleaning blade is greatly reduced. FIG. 10A shows an AFM observation image of the lubricant film after the run, and FIG.

  In FIG. 10, although the terrace of the lamella layer is recognized, a lot of fine lamella powder is adhered to the surface layer. When the leveling function is weak, the lamellar layer is not sufficiently grown on the laminate by lateral fusion and longitudinal lamination, and as a result, the outermost lubricant film does not reach a good state. The amplitude distribution curve in FIG. 10B is almost Gaussian distribution, and it can be seen that a flat portion is hardly formed at the highest portion. However, even in this state, if the supply condition of the lubricant and the pressure contact condition by the rubbing material are appropriate, the state can be shifted to a good state.

(Example 3)
From Example 1, first, the rubbing pressure between the solid lubricant and the fur brush was increased by 30%, and the supply of the lubricant was increased. After the application, pressure contact with an elastic blade was further performed 20 times. The photoconductor is mounted as the photoconductor of the image forming apparatus (1), repeated (run) 500 times under the same conditions as in Example 1, and the lubricant film after the run is again observed with an atomic force microscope. did. FIG. 5 (a) shows an observation image of this lubricant film by AFM, and FIG. 5 (b) shows its form analysis.

  In FIG. 5, the lubricant forms a more ideal lamellar laminate. As is apparent from FIG. 5B, at least locally, the unevenness of the surface of the lubricant film is only a single lamellar layer, and the area ratio between the highest flat part and the flat part of the valley is approximately 2. : 1. Further, it forms a ripple pattern having a pitch of several hundreds of nanometers and being substantially parallel and equally spaced. Under the condition that the supply of the lubricant and the leveling effect by the elastic member are well balanced, it is estimated that such a ripple pattern appears as a result of fine vibration of the blade tip. In other words, this pattern has an action of time dispersion in an alternating manner so that the contact friction is so-called, and ensures stable and continuous lubricity. The film thickness obtained by the X-ray reflectivity analysis method based on the previous Parratt simulation is about 20 nm, and the lubricant film is a lamellar layer laminate of at least four layers.

(Comparative Example 1)
The supply of the lubricant was canceled and the blade contact pressure was increased by 50%, and the same run as in Example 2 was performed 500 times in the same manner. FIG. 11A shows an AFM observation image of the lubricant film after the run, and FIG. The disappearance of the lubricant film and the accompanying significant deterioration of the photoreceptor surface were observed.

(Example 3)
Instead of the photoreceptor of Example 1, a surface protective layer having a film thickness of about 3 μm formed by dispersing 40% by mass of alumina fine particles having an average primary particle size of 0.4 μm in polycarbonate on the surface layer of the same material is sprayed. A photoreceptor provided by coating was used. Under the condition of non-lubricant application (releasing the application fur brush), a fine flaw of the blade and a cleaning defect associated therewith appeared about 300 times. This photoconductor was coated with a lubricant under the same conditions as in Example 2 and run under the same conditions as in Example 1. Even after 3000 runs, both the cleaning failure and the charge deterioration were within the level of no practical problem.

(Comparative Example 2)
Polytetrafluoroethylene (PTFE) was applied to the surface of the photoreceptor used in Example 1 via a rubbing brush, and the adhesion state was observed by AFM (phase image in tapping mode). This aspect is shown in FIG. PTFE was found to be a spider web frayed with fine fibers having a thickness of several tens of nm to cover the adherend, and the coverage was 30% at most. That is, it has been demonstrated from the adhesion mode that the fluorine-based polymer is excellent in low friction, but has a lower coverage than the lamellar laminate and is greatly inferior in terms of the protective effect against discharge.

  According to the present invention, the lubricating effect of the lubricant film and the protection function against charging are stably maintained, a high-quality image can be obtained over a long period of time, and a long life can be achieved, A process cartridge and an image forming method are provided.

It is an observation image (stearic acid crystal piece) by an atomic force microscope for demonstrating a lamella layer. It is an observation image (zinc stearate) by an atomic force microscope for demonstrating a lamellar layer leaf-like flake. It is an observation image (zinc stearate) by an atomic force microscope for demonstrating fusion | bonding of a lamellar layer leaf-like flake. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with Example 1. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with Example 3. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with Example 2. It is explanatory drawing of an amplitude distribution curve (ADC) and a load curve (BAC). It is a figure which shows the surface analysis example (titanium oxide fine particle dispersion layer surface) by a child force microscope in a typical rough surface. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with Example 1. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film concerning the reference example 2. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with the comparative example 1. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with Reference Example 1. It is the observation image and analysis figure by an atomic force microscope of the zinc stearate film in connection with Reference Example 1. 1 is a schematic configuration diagram for explaining an example of an image forming apparatus of the present invention. It is a figure for demonstrating another example of the image forming apparatus of this invention. FIG. 2 is a schematic configuration diagram showing a layer configuration of an amorphous silicon photoreceptor used in the image forming apparatus of the present invention. It is a figure for demonstrating an example of the process cartridge of this invention. It is an observation image (Phase Image) of a polytetrafluoroethylene coating film related to Comparative Example 2 using an atomic force microscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoconductor 3 Charging roller 4 Exposure part 5 Development part 6 Transfer part 7 Paper transfer part 8 Static elimination part 13 Photoconductor cleaning part 20 Process cartridge 50 Electrophotographic photosensitive member 51 Support body 52 Photoconductive layer 53 Amorphous silicon system Surface layer 500 Solid lubricant 502 Fur brush P Recording paper

Claims (18)

  At least an image carrier, a charging member that is disposed in contact with or close to the image carrier, a charging unit that applies a voltage to the charging member to charge the image carrier, and charging by the charging unit An image forming apparatus comprising: a latent image forming unit that forms an electrostatic latent image on the surface of the image bearing member formed; and a developing unit that attaches toner to an image portion of the electrostatic latent image formed by the latent image forming unit. In the apparatus, the image forming apparatus further includes a lubricant supply device that supplies a lubricant to the surface of the image carrier, wherein the lubricant is a lubricant having a lamellar structure, and the lubricant is a laminated layer having a lamellar structure. An image forming apparatus in which a film is formed on the surface of the image carrier as a body.   The image forming apparatus according to claim 1, wherein the wear of the lubricant caused by the operation of the image forming apparatus and the supply of the lubricant by the lubricant supply device are substantially in a balanced state.   3. The image forming apparatus according to claim 2, wherein when the surface of the image carrier is used as a reference plane, an amplitude distribution curve on the surface of the coating has a plurality of maximum values.   The lubricant supply device includes: an application member that applies a lubricant to the surface of the image carrier; and a leveling member that makes the lubricant applied to the image carrier uniform. 3. The image forming apparatus according to 3.   The image forming apparatus according to claim 4, wherein the lubricant is a fatty acid metal salt.   The fatty acid in the fatty acid metal salt contains at least one fatty acid selected from the group consisting of stearic acid, palmitic acid, myristic acid and oleic acid, and the metal is composed of zinc, aluminum, calcium, magnesium and lithium. The image forming apparatus according to claim 5, comprising at least one metal selected from the group consisting of:   The image forming apparatus according to claim 6, wherein the fatty acid metal salt is mounted in the lubricant supply device as a solidified solid fatty acid metal salt.   The image forming apparatus according to claim 7, wherein the solid fatty acid metal salt is zinc stearate.   9. The image forming apparatus according to claim 8, wherein the solid fatty acid metal salt also serves as an application member, and the lubricant is supplied by bringing the solid fatty acid metal salt into contact with the image carrier.   The image forming apparatus according to claim 4, wherein a fur brush is used as the application member.   The image forming apparatus according to claim 1, wherein the toner has a circularity of 0.96 or more.   The image forming apparatus according to claim 1, wherein the image carrier includes amorphous silicon.   The image forming apparatus according to claim 1, wherein the image carrier is OPC (organic photoreceptor) in which a filler is dispersed and strengthened on a surface layer.   The image forming apparatus according to claim 1, wherein the image carrier is OPC using a cross-linked charge transport material.   The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus that forms an image by superposing toner a plurality of times.   A process cartridge comprising at least the lubricant supply device according to claim 1, a charging unit, and an image carrier, wherein the process cartridge is configured to be detachable from an image forming apparatus main body.   The process cartridge according to claim 16, further comprising the charging member according to claim 1. In the image forming method, comprising charging the surface of the image carrier, forming an electrostatic latent image, and attaching toner to the image portion of the electrostatic latent image, a lubricant is supplied to the surface of the image carrier by a lubricant supply device. And the lubricant is a lubricant having a lamellar structure, and the lubricant is coated on the surface of the image carrier as a laminate having a lamellar structure.

Images