JP2007065018A - Lubricant applying device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the application quantity of a lubricant onto an intermediate transfer member in a proper range so that the intermediate transfer member prevents blade rolling-in to retain good cleaning property, and can maintain good primary transfer performance. <P>SOLUTION: A belt cleaning device is provided which applies a lubricant to the surface of an intermediate transfer belt which carries toner images in an overlapped state by transferring the toner images formed on a photoreceptor two or more times, wherein zinc stearate is used as the lubricant and this lubricant is applied in an amount of 1×10<SP>4</SP>to 8×10<SP>4</SP>mg per 1 km<SP>2</SP>movement area of the intermediate transfer belt to adjust the surface friction coefficient μs of the intermediate transfer belt to a range of 0.3 to 0.45. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a fax machine, a printer, and the like, and a lubricant application unit employed in the image forming apparatus.

  2. Description of the Related Art Conventionally, there is a wide variety of image forming apparatuses that form a color image by primary transfer of each color toner image on a photoconductor onto an intermediate transfer member for each color and superimposing and secondary transfer from the intermediate transfer member onto a recording member. Known (for example, Patent Document 1). In this image forming apparatus, toner remaining on the intermediate transfer member after the secondary transfer is cleaned by an intermediate transfer member cleaning device such as a blade or a brush roller.

  As the intermediate transfer member, an intermediate transfer belt having a multilayer structure composed of a base layer, an elastic layer, and a surface coat layer is widely used. Specifically, an elastic layer provided on a base layer such as a fluororesin, PVD sheet, or polyimide resin with little elongation is covered with a smooth surface coat layer such as a fluororesin. This surface coat layer prevents contamination of the photoconductor by the elastic layer, reduces the surface friction resistance of the intermediate transfer belt, weakens the adhesion between the intermediate transfer belt and the toner, and improves the cleaning property and the secondary transfer property. It has a function. Further, Patent Document 2 discloses that the coefficient of static friction on the surface of the intermediate transfer belt is in the range of 0.1 to 0.4 in order to improve the cleaning property and the secondary transfer property.

  In addition, with recent improvements in image quality, toner particles have become smaller and spherical with polymerized toner, and with this toner improvement, the intermediate transfer belt considering the above-mentioned cleaning properties can also maintain the cleaning properties over time. Is getting harder. Specifically, in the polymerized toner that supports high image quality, the wax component is uniformly dispersed inside the toner, so that the precipitation of the wax component to the outside is small when the toner adheres to the intermediate transfer belt, and the intermediate transfer over time The static friction coefficient of the belt surface will rise to 0.5 or more. When the surface friction coefficient of the intermediate transfer belt increases, blade entrainment tends to occur, and when the blade entrainment occurs, cleaning failure occurs. Also, filming on the intermediate transfer belt is likely to occur.

  Therefore, Patent Document 2 also discloses that a lubricant application device that applies a lubricant to reduce the surface friction coefficient of the intermediate transfer belt is provided.

Japanese Patent Laid-Open No. 5-323704 JP 2004-177442 A

  In the image forming apparatus disclosed in Patent Document 2, good initial cleaning properties of the intermediate transfer belt can be obtained by the multilayer structure of the intermediate transfer belt. Further, by providing a lubricant application device that applies a lubricant onto the intermediate transfer belt, it is possible to improve the cleaning properties with time. However, if the amount of lubricant applied to the surface of the intermediate transfer belt becomes excessive and the surface friction coefficient becomes too low, some of the dots, characters, lines, etc. are lost during the primary transfer from the photoconductor to the intermediate transfer belt. An abnormal image such as an image omission is likely to occur. For this reason, the amount of lubricant applied must be kept below a certain level. Therefore, the amount of lubricant applied on the intermediate transfer belt is set within an appropriate range so that the blade can be prevented from getting caught over time to maintain good cleaning performance and good primary transferability. It is desirable to find application conditions.

  Note that, in a lubricant application device that applies a lubricant onto a photoconductor, the proper range of the lubricant application amount is defined in consideration of the transfer performance from the photoconductor to the transfer body and the cleaning performance. On the other hand, the transfer performance when the transfer from the photoreceptor onto the intermediate transfer belt is performed a plurality of times and the toner images are superimposed on the intermediate transfer belt is the transfer performance of the second and subsequent colors compared to the transfer of the first color. Is severe and tends to generate worm-eating prints. Therefore, in the lubricant application device that applies the lubricant onto the intermediate transfer belt, the appropriate range of the lubricant applied to the intermediate transfer belt from the viewpoint of transfer performance is stricter than the appropriate range of the lubricant applied to the photoreceptor. It is considered to be.

  The present invention has been made in view of the above background, and the object of the present invention is to prevent the intermediate transfer member from being caught in the blade to maintain good cleaning properties and to maintain good primary transfer performance. Thus, it is an object of the present invention to provide a lubricant application device and an image forming apparatus capable of keeping the amount of lubricant applied to an intermediate transfer member in an appropriate range.

In order to achieve the above object, the invention according to claim 1 is directed to an intermediate transfer member for transferring a toner image formed on a latent image carrier a plurality of times to carry the toner image in a superimposed state. In a lubricant application device for applying a lubricant to the surface, zinc stearate as the lubricant is used in an amount of 1 × 10 ⁴ mg or more and 8 × 10 ⁴ mg or less per square kilometer of moving area of the intermediate transfer member. The intermediate transfer member is coated so that the surface friction coefficient μs is in the range of 0.3 to 0.45.
According to a second aspect of the present invention, in the lubricant application device of the first aspect, a brush roller is used as a member for applying zinc stearate to the intermediate transfer member.
The invention according to claim 3 is the lubricant application apparatus according to claim 2, wherein the rotational load torque of the brush roller is 300 gf · cm or less when the stationary member is pressed by 1 kgf. is there.
The invention according to claim 4 is the lubricant application apparatus according to claim 3, wherein the hardness of zinc stearate as the lubricant is a solid having a micro Vickers hardness of 2.0 or more and 6.0 or less. It is.
According to a fifth aspect of the present invention, in the lubricant application device of the second, third, or fourth aspect, the brush roller has a flocking density of 9300 / cm ² or less, and the brush roller has a fineness of 6 denier or less. It is characterized by this.
According to a sixth aspect of the present invention, in the lubricant application device of the fifth aspect, the brush roller is made of nylon fiber.
According to a seventh aspect of the present invention, there is provided an image carrier that carries a toner image, an intermediate transfer member that carries the toner image by primary transfer of the toner image on the image carrier, and a surface of the intermediate transfer member In the image forming apparatus provided with a lubricant application device for applying a lubricant to the lubricant, the lubricant application device according to any one of claims 1, 2, 3, 4, 5 or 6 is adopted as the lubricant application device. It is characterized by this.
According to an eighth aspect of the present invention, in the image forming apparatus of the seventh aspect, the lubricant applying device also serves as a cleaning device for the intermediate transfer member.
According to a ninth aspect of the present invention, in the image forming apparatus of the seventh or eighth aspect, the toner used for toner image formation has a volume average particle diameter (Dv) of 3 to 8 μm and a volume average particle diameter (Dv ) And the number average particle diameter (Dn) (Dv / Dn) is in the range of 1.00 to 1.40.
According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. It is a feature.
The invention according to claim 11 is the image forming apparatus according to claim 9 or 10, wherein the toner contains at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent in an organic solvent. It is a toner obtained by cross-linking and / or stretching reaction of a toner material liquid dispersed in a water-based medium.
According to a twelfth aspect of the present invention, in the image forming apparatus of the ninth, tenth, or eleventh aspect, the toner has a substantially spherical shape.
According to a thirteenth aspect of the present invention, in the image forming apparatus according to the ninth, tenth, or eleventh aspects, the shape of the toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (provided that r1 ≧ r2 ≧ r3 The ratio (r2 / r1) between the major axis r1 and the minor axis r2 is in the range of 0.5 to 1.0, and the ratio (r3 / r2) between the thickness r3 and the minor axis r2 is 0. It is characterized by being in the range of 7 to 1.0.

In these inventions, zinc stearate as a lubricant is applied at 1 × 10 ⁴ or more and 8 × 10 ⁴ mg or less per square kilometer of moving area of the intermediate transfer member, and the surface friction coefficient μs of the intermediate transfer member. Is in the range of 0.3 to 0.45. As a result, as shown in an experiment to be described later, it is possible to prevent blade entrainment, maintain good cleaning properties, and maintain good primary transfer performance. Specifically, from the relationship between the static friction coefficient μs of the intermediate transfer body shown in FIG. 3 described later and the worm-eating rank at the time of primary transfer, the static friction coefficient μs of the intermediate transfer body is set to 0.3 or more, so that the toner Good transfer performance can also be obtained during primary transfer in which images are superimposed. Further, from the relationship between the static friction coefficient μs of the intermediate transfer member and the occurrence of blade entrainment shown in FIG. 4 described in detail later, the entrainment of the blade is prevented by setting the static friction coefficient μs of the intermediate transfer member to 0.45 or less. be able to. Therefore, it is necessary to apply a lubricant so that the static friction coefficient μs of the intermediate transfer member is 0.3 to 0.45. For this purpose, as shown in FIG. 5, which will be described in detail later, from the relationship between the coating amount of zinc stearate as a lubricant and the static friction coefficient μs of the intermediate transfer member, the movement area of the intermediate transfer member is 1 square kilometer. By applying 1 × 10 ⁴ or more and 8 × 10 ⁴ mg or less per torr, the static friction coefficient of the intermediate transfer member can be in the range of 0.3 to 0.45.

  According to the first to thirteenth aspects of the present invention, the lubricant is applied onto the intermediate transfer member so that the intermediate transfer member can prevent blade entrainment and maintain good cleaning performance and maintain good primary transfer performance. There is an excellent effect that the amount can be kept in an appropriate range.

  Hereinafter, an embodiment in which an image forming apparatus to which the present invention is applied is applied to an electrophotographic color printer will be described. FIG. 1 is a schematic diagram of the overall configuration of a color printer according to an embodiment of the present invention. In this color printer, four toner image forming units 2M, Y, C, and K of magenta, cyan, yellow, and black are arranged side by side to constitute a tandem image forming unit. In the tandem image forming unit, the individual toner image forming units 2M, Y, C, and K are sequentially arranged from the left in the drawing. Here, the subscripts M, Y, C, KY, C, M, and K of the respective symbols indicate members for magenta, cyan, yellow, and black, respectively. In the tandem image forming unit, each of the toner image forming units 2M, Y, C, and K includes a drum-shaped photosensitive member 1M, Y, C, and K as a latent image carrier.

  The toner image forming units 2M, Y, C, and K for the respective colors may be formed as a single unit and may be a process cartridge that can be attached to and detached from the main body. These process cartridges can be pulled out from the printer body along guide rails (not shown) fixed to the printer body. Further, the toner image forming means 2M, Y, C, and K can be loaded at predetermined positions by pushing the process cartridge into the printer main body.

  Here, the toner image forming units 2M, Y, C, and K perform the same configuration and operation, respectively. Therefore, the subscripts M, Y, C, and K of the respective symbols are omitted below, and the toner image forming unit 2 will be described in detail. FIG. 2 is a schematic configuration diagram of the toner image forming unit. A charging device 3, a developing device 5, and a cleaning device 6 are arranged in this order around the photosensitive member 1 that rotates in the clockwise direction in the drawing.

  An exposure device 4 as a latent image forming unit is provided below the tandem image forming unit. The exposure device 4 is configured to irradiate the surface of each photoconductor 1 while scanning with laser light based on image data.

  An intermediate transfer belt 11 as an intermediate transfer device is provided immediately above the tandem image forming unit. The intermediate transfer device also includes primary transfer rollers 20M, Y, C, and K for transferring the toner image formed on each photoreceptor 1 onto the intermediate transfer belt 11. Further, support rollers 10, 12, 34, and 35 for supporting the intermediate transfer belt 11 are provided, and the intermediate transfer belt 11 can be rotated counterclockwise in the drawing. Of these support rollers, the roller 34 is a drive roller. The support rollers 12 and 35 are driven rollers and have a function of stabilizing the primary transfer nip. The support roller 10 is a cleaning facing roller, and also serves as a tension roller for the intermediate transfer belt 11, and functions to apply a constant tension to the intermediate transfer belt 11. Further, a secondary transfer device is provided on the opposite side of the support roller 35 downstream of the primary transfer rollers 20M, Y, C, and K with respect to the driving direction of the intermediate transfer belt 11. The secondary transfer device includes a secondary transfer belt 100, which is an endless belt, spanned between two rollers 111 and 112, and is disposed so as to press against the support roller 35 via the intermediate transfer belt 11. Then, as will be described later, the superimposed toner image on the intermediate transfer belt 11 is secondarily transferred collectively onto a recording material conveyed by the secondary transfer belt 100. A belt cleaning device 25 for removing residual toner remaining on the intermediate transfer belt 11 after image transfer is provided to the left of the support roller 10 downstream of the secondary transfer position with respect to the driving direction of the intermediate transfer belt 11.

Some secondary transfer devices use a secondary transfer roller. FIG. 2 is a schematic diagram of a configuration using a secondary transfer device using a secondary transfer roller. In the apparatus of FIG. 2, a secondary transfer roller 36 as a secondary transfer device is provided on the opposite side of the support roller 34 downstream of the primary transfer rollers 20M, Y, C, and K with respect to the driving direction of the intermediate transfer belt 11. Yes. Here, the support roller 34 functions as a pressing member.

  In addition, a fixing device 30 for fixing the toner image on the recording medium is provided above the secondary transfer device. The fixing device 30 is configured by pressing a pressure roller against a fixing roller.

  A lower part of the printer is provided with a paper feeding unit. The paper feed unit includes a paper feed roller 27, a registration roller 28, a transport path 29, and the like that transport the recording medium from the paper feed cassettes 26-1 and 26-2 to the secondary transfer region.

  Next, the operation of the printer will be described. Each photoconductor 1 is rotated by the individual toner image forming units 2M, Y, C, and K, and the surface of the photoconductor 1 is uniformly charged by the charging device 3 as the photoconductor 1 rotates. Next, the image data is irradiated with writing light by a laser from the exposure device 4 to form an electrostatic latent image on each photoconductor 1. Thereafter, toner is attached by each developing device 5 to visualize the electrostatic latent image, thereby forming magenta, cyan, yellow, and black single-color images on each photoconductor 1. Further, the intermediate transfer belt 11 is rotated and conveyed by a drive motor (not shown), and the visible image is sequentially transferred onto the intermediate transfer belt 11 by the primary transfer rollers 20M, Y, C, and K. As a result, a composite color image superimposed on the intermediate transfer belt 11 is formed.

  In accordance with the timing of image formation, the leading edge of the recording medium in the paper feed cassettes 26-1 and 26-2 is fed out by the paper feed roller 27, conveyed to the registration roller 28, and temporarily stops. Then, the sheet is conveyed between the secondary transfer device and the intermediate transfer belt 11 while taking the timing with the image forming operation. Here, the intermediate transfer belt 11 and the secondary transfer device form a so-called secondary transfer nip across the recording medium, and the secondary transfer device transfers the superimposed toner image on the intermediate transfer belt 11 onto the recording medium. Next transfer.

  The recording medium after the secondary transfer is sent to the fixing unit 30, heat and pressure are applied to the fixing unit to fix the transferred image, and the recording medium is discharged to the outside by the discharge roller 32 and stacked on the discharge tray 40. Is done. On the other hand, the intermediate transfer belt 11 after image transfer is removed by the belt cleaning device 25 to remove residual toner remaining on the intermediate transfer belt 11 and prepared for re-image formation by the tandem image forming unit.

  Here, in the intermediate transfer belt 11 employed in the intermediate transfer device, the base layer is made of, for example, a fluororesin, a PVD sheet, or a polyimide resin with little elongation, and the surface of the elastic layer provided on the base layer is made of a fluororesin It has a multilayer structure covered with a smooth surface coat layer. This surface coat layer has a function of preventing the contamination of the photoreceptor 1 by the elastic layer and reducing the surface frictional resistance of the intermediate transfer belt 11. However, due to recent improvements to improve the image quality of the toner, there is little precipitation of the wax component when the toner adheres to the intermediate transfer belt 11, and the surface frictional resistance of the surface of the intermediate transfer belt 11 increases with time. There is a trend. For this reason, there is a possibility that the cleaning blade may be caught or the surface of the intermediate transfer belt 11 may be filmed over time, and it is necessary to apply a lubricant to the intermediate transfer belt 11 to reduce the surface frictional resistance.

  Therefore, in the color printer of this embodiment, the belt cleaning device 25 of the intermediate transfer belt 11 has a mechanism as a lubricant application device that applies lubricant to the intermediate transfer belt. Hereinafter, application of the lubricant to the intermediate transfer belt 11 will be described with reference to FIG. The belt cleaning device 25 includes a cleaning blade 21, a rotatable roller-shaped application brush 22, a solid lubricant 23, and a pressure spring as an urging unit that urges the solid lubricant 23 toward the application brush 22. 24. The cleaning blade 21 contacts the intermediate transfer belt 11 and scrapes off the transfer residual toner from the surface thereof. The application brush 22 scrapes off and applies the solid lubricant 23 pressed by the pressure spring 24 to the intermediate transfer belt 11 while rotating. As described above, the belt cleaning device 25 has a function as a cleaning device that cleans the transfer residual toner on the intermediate transfer belt 11 and a function as a lubricant application device that applies a lubricant to the surface of the intermediate transfer belt 11. Yes.

  Further, in such a belt cleaning device 25, if the amount of lubricant applied is too large, the surface frictional resistance on the surface of the intermediate transfer belt 11 is too low, and during the primary transfer from the photoreceptor 1 to the intermediate transfer belt 11. Abnormal images such as worm-eating prints are likely to occur. For this reason, the amount of lubricant applied must be kept below a certain level.

  Therefore, the present inventors conducted the following experiment in order to find an appropriate range of the lubricant application amount in the belt cleaning device 25. First, the relationship between the static friction coefficient μs on the surface of the intermediate transfer belt 11 and the worm-eating rank as the primary transfer performance was examined. Here, as the photosensitive member 1 used in the color printer, a surface in which the photosensitive member surface is provided with a layer containing lubricant fine particles in order to improve the transfer performance in order to improve the transfer performance. The present applicant has proposed a method for suppressing the increase in the friction coefficient (Japanese Patent Laid-Open No. 2005-134791). Therefore, two types of photoconductors were used: a normal photoconductor (hereinafter referred to as “without mars”) and a photoconductor (hereinafter referred to as “with mars”) in which the increase in the friction coefficient of the surface was suppressed. As the toner, SPR-C, which is one of polymerization and small particle size toner described later, was used. In SPR-C, since the wax component is uniformly dispersed inside the toner, there is little precipitation of the wax component to the outside when the toner adheres to the intermediate transfer belt 11, and the surface friction resistance on the surface of the intermediate transfer belt 11 is reduced over time. It is easy to rise. 3A and 3B show the results of examining the relationship between the static friction coefficient μs of the intermediate transfer belt 11 and the primary transfer performance to the intermediate transfer belt 11 under such conditions. From this result, it can be seen that the primary transfer performance when toner images are superimposed is more severe in the second and subsequent colors than in the first color, and worms are more likely to occur. Further, as shown in FIG. 3A, the primary transfer performance from the photoreceptor 1 without a mars is that the intermediate transfer belt 11 of the intermediate transfer belt 11 is not less than rank 4 where the worm-eating rank is acceptable even in the second color. The coefficient of static friction μs is required to be 0.3 or more. Further, as shown in FIG. 3B, in order to achieve the primary transfer performance from the photosensitive member 1 with a mals or the rank 4 or higher where the worm-eating rank is acceptable even in the second color, the intermediate transfer belt 11 is stopped. The friction coefficient μs is required to be 0.3 or more.

  Next, the relationship between the cleaning performance of the belt cleaning device 25 and the static friction coefficient μs on the surface of the intermediate transfer belt 11 was examined. The polymerization and small particle size toner represented by SPR-C cannot be established if the contact angle of the cleaning blade 21 is larger than 83 degrees. Accordingly, FIG. 4 shows the result of examining the relationship between the contact angle of the cleaning blade 21 and the static friction coefficient μs of the surface of the intermediate transfer belt 11 and the entrainment of the blade. FIG. 4 shows that the static friction coefficient μs needs to be 0.45 or less in order to improve the cleaning property when the contact angle of the cleaning blade 21 is 83 degrees or less and to prevent the blade from being caught.

For these reasons, in order to achieve both prevention of worm-eaten images and prevention of blade entrainment while ensuring cleaning performance, the static friction coefficient μs of the intermediate transfer belt 11 should be maintained in the range of 0.3 to 0.45. is required. Therefore, the conditions of the belt cleaning device 25 for maintaining the static friction coefficient μs of the intermediate transfer belt 11 in the range of 0.3 to 0.45 are examined. First, by using zinc stearate as the solid lubricant 24, a device that is easy to handle and inexpensive can be obtained. FIG. 5 shows the relationship between the coating amount of zinc stearate per 1 km travel distance of 312 mm in width of the intermediate transfer belt 11 and the static friction coefficient μs of the intermediate transfer belt 11. As shown in FIG. 5, in order to maintain the static friction coefficient μs of the intermediate transfer belt 11 in the above-described range of 0.3 to 0.45, the zinc stearate is applied per 1 km of the travel distance of the intermediate transfer belt 11. The amount needs to be 3 mg or more and 25 mg or less. When this is converted per 1 square kilometer (km ² ) of movement area of the intermediate transfer belt 11, 1 × 10 ⁴ mg or more and 8 × 10 ⁴ mg or less are applied.

Here, the static friction coefficient μs in the present embodiment is calculated by the following method using the Euler belt method. The intermediate transfer belt 11 for measurement is wrapped around a cylindrical one and fixed to a pedestal, and a high-quality paper (Ricoh Type 6200) cut into a width of 30 mm and a length of 297 mm is placed on the intermediate transfer belt 11 as a belt. A 100 g weight is attached to one end of the belt and the other end is attached to a digital force gauge. The digital force gauge is moved at a constant speed, and the static friction coefficient is calculated from the load at the start of belt movement using the following formula.
μs = 2 / π × ln (F / W)
Here, μs is a static friction coefficient, F is a reading load, W is a weight of a weight, and π is a circumference ratio. This measurement method is a calculation formula derived from Euler's formula.

  In addition, the application of zinc stearate to the intermediate transfer belt 11 is more stable by applying using the brush roller 22 as described above, as compared to applying zinc stearate to the intermediate transfer belt 11 by direct contact. The amount can be controlled.

  In order to make the amount of zinc stearate applied by the brush roller 22 within the above range, it is important to define the force with which the brush roller 22 scrapes off the zinc stearate. The inventors defined this scraping force by the rotational load torque of the brush roller. As shown in FIG. 6, the rotational load torque of the brush roller 22 is measured by pressing a 1 kg weight 60 against the brush roller with its own weight. FIG. 7 shows the relationship between the rotational load torque and the static friction coefficient μs of the intermediate transfer belt 11. As shown in FIG. 7, in order to maintain the static friction coefficient μs of the intermediate transfer belt 11 in the above-described range of 0.3 to 0.45, the rotational load torque of the brush roller is 50 gf · cm or more and 300 gf · cm. Must be:

  Moreover, in order to make the coating amount of zinc stearate within the above range, the coating amount can be controlled by setting the hardness of zinc stearate to a micro Vickers hardness of 2.0 or more and 6.0 or less.

In order to make the rotational load torque of the brush roller 22 within the above range, it is important to define the fiber thickness and the flocking density of the brush roller 22. As shown in FIG. 8, in order to obtain a rotational torque of 300 gf · cm or less, the fineness (denier) that defines the thickness of the fiber is 6 d or less, and the flocking density is 60 × 10 ³ filaments per square inch. In terms of conversion, it is necessary to make it 9300 or less per square centimeter.

  Moreover, the result of having examined about the material of the brush roller 22 is shown in FIG. As shown in FIG. 9, when comparing acrylic fiber and nylon fiber as the material of the brush roller 22, the nylon fiber is more in the static friction of the intermediate transfer belt 11 for the same rotational load torque in the range of 150 to 300 gf · cm. It can be seen that the coefficient μs is high and the appropriate range of 0.3 to 0.45 is satisfied. Also, considering the image printing rate, if the rotational load torque is reduced, the printing rate becomes intermediate to the printing rate. There is a tendency that the variation of the surface μs of the transfer body increases. For this reason, it is difficult to reduce the rotational load torque to 150 gf · cm or less with acrylic fiber due to large variations. Therefore, nylon fiber is the most suitable brush roller material that satisfies the appropriate range of the static friction coefficient μs of 0.3 to 0.45.

Next, the toner suitably used for the color printer of the present invention will be described.
In order to reproduce minute dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. FIG. 10 is a diagram schematically showing the shape of the toner in order to explain the shape factor SF-1. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.

SF-1 = {(MXLNG) 2 / AREA} × (100π / 4) Formula (1)

When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases. FIG. 10 is a diagram schematically showing the shape of the toner in order to explain the shape factor SF-2. The shape factor SF-2 indicates the ratio of unevenness in the shape of the toner, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.

SF-2 = {(PERI) 2 / AREA} × (100π / 4) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent. Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated. When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

  In addition, a toner suitably used for a color printer is a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent are dispersed in an organic solvent. Is a toner obtained by crosslinking and / or elongation reaction in an aqueous solvent. Hereinafter, the constituent material and the manufacturing method of the toner will be described.

(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound.
Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable. Examples of the dihydric alcohol (DIO) 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 above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. As trihydric or higher polyhydric alcohol (TO), 3 to 8 or higher polyhydric aliphatic alcohol (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) 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) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1. The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, it tends to be negatively charged, and furthermore, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation. The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

  In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines. Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-isocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; phenol derivatives, oximes, caprolactam And a combination of two or more of these. The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated. The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates. The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (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 B1 to B5 blocked amino groups (B6) include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 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.

The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is less than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.
The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

  The urea-modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.

When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. 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.) and ethers And those inert to isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran).
In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).
The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.

By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.
The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.
The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.
In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

(Coloring agent)
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Lid Russian nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.

  The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of a master batch or a master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene, or a substituted product thereof, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.
The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 −3 to 2 μm, and particularly preferably 5 × 10 −3 to 0.5 μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle diameter of 5 × 10 ⁻⁴ μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed to obtain a good image quality that does not cause the release of the fluidity imparting agent from the toner and does not generate firefly, etc., and further reduces the residual toner. It is done. Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large. However, when the added amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if

Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.
(Toner production method)
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, 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 can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.

Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.

Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.
Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (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, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

  In addition, examples of the cationic surfactant include aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, and perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salts. , Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (manufactured by Asahi Glass), Florard FC-135 (manufactured by Sumitomo 3M), Unidyne DS-202 (Daikin Industries) Manufactured), MegaFuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products Co., Ltd.), Footgent F-300 (Neos Co., Ltd.), and the like.

  The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.). In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Bodies such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and 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. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.

5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner.
The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

The toner has a substantially spherical shape and can be represented by the following shape rule. 12A, 12B, and 12C are diagrams schematically showing the shape of the toner. In FIGS. 12A, 12B, and 12C, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the main toner is defined. The toner of the invention has a ratio (r2 / r1) between the major axis and the minor axis (see FIG. 12B) of 0.5 to 1.0, and a ratio between the thickness and the minor axis (r3 / r2) (FIG. 12 (c)) is preferably in the range of 0.7 to 1.0. When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved.
Note that r1, r2, and r3 were measured with a scanning electron microscope (SEM) while changing the angle of field of view and taking pictures.

As described above, in the color printer according to the present embodiment, zinc stearate is used as the lubricant so that the static friction coefficient μs of the intermediate transfer belt is in the range of 0.3 to 0.45, and the moving area of the intermediate transfer belt 11 is increased. 1 × 10 ⁴ mg or more and 8 × 10 ⁴ mg or less are applied per square kilometer. By applying such a lubricant application condition, the amount of lubricant applied onto the intermediate transfer belt can be maintained so that the intermediate belt can prevent blade entrainment, maintain good cleaning properties, and maintain good transfer performance. It can be kept in the proper range.
Further, by using the brush roller 22 as means for applying the lubricant to the intermediate transfer belt 11, a stable application amount can be obtained.
In order to control the application condition of zinc stearate by the brush roller 22 within the above range, it is effective to set the scraping force of the brush roller 22 to 300 gf · cm or less.
In order to control the application condition of zinc stearate by the brush roller 22 within the above range, it is effective to set the hardness of zinc stearate to a micro Vickers hardness of 2.0 or more and 6.0 or less.
In addition, in order to obtain a load torque of 300 gf · cm or less of the rotational load torque of the brush roller 22, the fineness (denier) that defines the fiber thickness should be 6 d or less, and the flocking density should be 9300 or less per square centimeter. It is valid.
In order to control the application condition of zinc stearate by the brush roller 22 within the above range, nylon fiber is optimal as the material of the brush roller.
Further, the lubricant application device also serves as the belt cleaning device 25, so that the device can be simplified.
The toner used in the color printer has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of 1.00 to 1.n. It shall be in the range of 40. Thereby, it is possible to obtain a high-definition and high-quality image with little background fog.
The toner has a shape factor SF-1 in the range of 100 to 180, and a shape factor SF-2 in the range of 100 to 180. When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases. In the shape factor SF-2, when the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent. When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.
In addition, the toner includes at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, and a toner material liquid in which a colorant and a release agent are dispersed in an organic solvent. It is a toner obtained by an extension reaction. Thereby, a high quality image can be obtained.
In addition, since the toner has a substantially spherical shape, a high-quality image can be obtained.
Further, the shape of the toner is defined by the major axis r1, the minor axis r2, and the thickness r3 (where r1 ≧ r2 ≧ r3), and the ratio of the major axis r1 to the minor axis r2 (r2 / r1) is 0. It is assumed that the ratio (r3 / r2) between the thickness r3 and the minor axis r2 is in the range of 0.7 to 1.0. Thereby, a high quality image can be obtained.

1 is a schematic configuration diagram of a color printer according to an embodiment of the present invention. 1 is a schematic configuration diagram of an intermediate transfer device. (A), (b) The graph which shows the relationship between the static friction coefficient (micro | micron | mu) s of the surface of an intermediate transfer belt, and the worm-eaten rank of primary transfer. A graph showing the relationship between the static friction coefficient μs on the surface of the intermediate transfer belt and the blade entrainment. 6 is a graph showing the relationship between the coating amount of zinc stearate per 1 km travel distance of the intermediate transfer belt and the static friction coefficient μs of the intermediate transfer belt. Measuring method of rotational load torque of brush roller. 6 is a graph showing the relationship between the rotational load torque of the brush roller and the static friction coefficient μs of the intermediate transfer belt 11. The graph which shows the relationship between the thickness of the fiber of a brush roller, the flocking density, and rotational load torque. The graph which shows the relationship between the material of a brush roller, and the static friction coefficient (microsecond) of an intermediate transfer belt. The figure which represented the shape of the toner typically in order to demonstrate shape factor SF-1. The figure which represented the shape of the toner typically in order to demonstrate shape factor SF-2. (A), (b), (c) The figure which shows the shape of a toner typically

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2M, C, Y, K Toner image formation means 3 Charging apparatus 4 Exposure apparatus 5 Developing apparatus 10 Support roller 11 Intermediate transfer belt 12 Support roller 20 Primary transfer roller 21 Cleaning blade 22 Brush roller 23 Solid lubricant 24 Pressure Spring 25 Belt cleaning device 26 Paper feed cassette 27 Paper feed roller 28 Registration roller 30 Fixing unit 34, 35 Support roller 36 Secondary transfer roller 60 Weight 100 Secondary transfer belt

Claims (13)

In a lubricant application device that applies a lubricant to the surface of an intermediate transfer member that carries the toner image in a superimposed state by transferring the toner image formed on the latent image carrier multiple times.
Zinc stearate as the lubricant is applied to 1 × 10 ⁴ mg or more and 8 × 10 ⁴ mg or less per square kilometer of moving area of the intermediate transfer member, and the surface friction coefficient μs of the intermediate transfer member is set. A lubricant application device having a range of 0.3 to 0.45.   2. The lubricant application device according to claim 1, wherein a brush roller is used as a member for applying zinc stearate to the intermediate transfer member.   3. The lubricant application device according to claim 2, wherein the rotational load torque of the brush roller is 300 gf · cm or less when the stationary member is pressed with 1 kgf.   4. The lubricant application device according to claim 3, wherein the hardness of zinc stearate as a lubricant is a solid having a micro Vickers hardness of 2.0 or more and 6.0 or less. 5. The lubricant application device according to claim 2, wherein the brush roller has a flocking density of 9300 / cm ² or less, and the brush roller has a fineness of 6 denier or less. .   6. The lubricant application device according to claim 5, wherein the brush roller is made of nylon fiber. An image carrier that carries a toner image, an intermediate transfer member that carries the toner image by primary transfer of the toner image on the image carrier, and a lubricant coating that applies a lubricant to the surface of the intermediate transfer member An image forming apparatus comprising:
An image forming apparatus, wherein the lubricant applying device according to any one of claims 1, 2, 3, 4, 5 and 6 is employed as the lubricant applying device.   8. The image forming apparatus according to claim 7, wherein the lubricant applying device also serves as a cleaning device for the intermediate transfer member.   9. The image forming apparatus according to claim 7, wherein the toner used for toner image formation has a volume average particle diameter of 3 to 8 μm, and a ratio between the volume average particle diameter (Dv) and the number average particle diameter (Dn). An image forming apparatus having (Dv / Dn) in a range of 1.00 to 1.40.   10. The image forming apparatus according to claim 9, wherein the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.   11. The image forming apparatus according to claim 9, wherein the toner includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent are dispersed in an organic solvent. An image forming apparatus comprising a toner obtained by crosslinking and / or elongation reaction in an aqueous medium.   12. The image forming apparatus according to claim 9, wherein the toner has a substantially spherical shape.   12. The image forming apparatus according to claim 9, wherein the shape of the toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (provided that r1 ≧ r2 ≧ r3), and the major axis r1 and the minor axis are short. The ratio (r2 / r1) to the axis r2 is in the range of 0.5 to 1.0, and the ratio (r3 / r2) of the thickness r3 to the minor axis r2 is in the range of 0.7 to 1.0. An image forming apparatus.

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