JP4494070B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus of a blade cleaning type using an electrophotographic process such as a copying machine, a printer, and a facsimile.

  An image forming method generally used in electrophotography, electrostatic recording, electrostatic printing, etc., develops an electrostatic latent image formed on an electrostatic latent image carrier such as a photosensitive member with toner, In the transfer step, toner is transferred from the photoreceptor to a transfer medium such as transfer paper, and then fixed on the paper surface in the fixing step to form an image. In the transfer process, a small amount of toner remains on the photoconductor, and cleaning is performed to remove the toner. The photosensitive member cleaning includes a blade method, a fur brush method, a mag brush method, and the like, but a blade cleaning method that is small and low in cost is often used. As a toner to be used for development, a toner binder such as a styrene resin or polyester is melt-kneaded with a colorant or the like and finely ground.

In recent years, there has been a tendency to further reduce the toner particle size in order to obtain a high-definition and high-quality image. However, if the particle size is reduced by a normal kneading or pulverizing method, the energy used and yield are reduced. The cost is very high and there is a limit to the pulverization of the particle size.
As a method for solving this problem, polymerized toner production methods such as suspension polymerization, emulsion polymerization aggregation, and dispersion polymerization have been proposed. Patent Document 1 proposes a method with volume shrinkage called a polymer dissolution suspension method. In this method, a toner material is dispersed and dissolved in a volatile solvent such as a low-boiling organic solvent, and this is emulsified and formed into droplets in an aqueous medium containing a dispersant, and then the volatile solvent is removed. Unlike suspension polymerization and emulsion polymerization agglomeration methods, this method is a versatile resin that can be used, especially polyester resins useful for full-color processes that require transparency and smoothness of the image area after fixing. It is excellent in that it can be used. However, many of the toners obtained by these production methods have a comparatively spherical shape, and have the disadvantage that the cleaning performance by the blade is remarkably poor although there is an advantage of excellent transferability and fluidity. Furthermore, there is a proposal to spheroidize the pulverized toner in order to improve the transfer property, but this also causes a problem that the blade cleaning property is lowered. Further, the reduction in the particle size of the toner itself has a problem that the blade cleaning property is lowered.

As a proposal to reduce the coefficient of friction of the photoconductor, there is a proposal to improve the durability of the photoconductor and the wrinkle of the cleaning blade by adding a fluorine resin to the surface layer of the photoconductor. However, a toner having a circularity of 0.93 or more could not be reliably cleaned with a blade.
In addition, as described in Patent Documents 2 and 3, there is also a proposal for improving the blade cleaning property by applying a lubricant such as a fatty acid metal salt to the surface of the photoreceptor. The blade could not be cleaned reliably.
Further, the toner that has passed through the cleaning blade reaches a charging device that charges the surface of the photoreceptor. In recent years, a charging roller formed in the shape of a roller with a conductive member is brought close to or in contact with the surface of the photosensitive member, and a voltage is applied between the charging roller and the photosensitive member in that state, thereby the photosensitive member. The charging device for charging the surface of the material has been put into practical use because it has the advantage of reducing ozone and reducing power consumption.

There are a DC voltage and an AC superposition type in the applied bias system. The method of applying a DC voltage is difficult in practical use due to problems such as variations in charging potential due to minute gap fluctuations and discharge stability. For this reason, in the case of non-contact, it is considered that the AC superposition type is a suitable method.
However, the transfer residual toner remaining on the surface of the photoconductor after the toner image transfer is not completely removed in the cleaning process, and when it reaches the charging portion and receives a strong discharge, it melts or increases the adhesive strength. Therefore, a so-called filming phenomenon occurs in which it tends to adhere to the surface of the photoreceptor. When the adhesion amount of the fine particles increases, there is a problem that a desired latent image is not formed on the photosensitive member, resulting in an abnormal image.

JP-A-7-152202 Japanese Patent Laid-Open No. 11-305470 JP 2002-107968 A

  In view of the above problems, the present invention prevents the toner from slipping through the cleaning blade, so that the untransferred toner on the photoreceptor adheres to the photoreceptor, or the photoreceptor and the charging roller, and the filming phenomenon occurs. It is an object of the present invention to provide an image forming apparatus that suppresses occurrence and prints a high-quality image.

In order to solve the above-mentioned problems, the present invention provides an image carrier that carries a latent image, a charging unit that charges the surface of the image carrier uniformly by superimposing an AC bias voltage on a DC bias voltage, and charging An exposure means for exposing the surface of the image carrier on the basis of image data and writing a latent image; and a latent image formed on the surface of the image carrier , the toner particles have a volume average particle diameter of 1 to 8 μm and an average circularity of 0. .Developing means for supplying 95 to 1.0 toner to visualize the image, transfer means for transferring the visible image on the surface of the image carrier to a transfer medium, and cleaning for cleaning the surface of the image carrier after the transfer A cleaning means having at least a cleaning blade for removing toner on the image carrier, and disposed upstream of the cleaning blade in the rotation direction of the image carrier, and applying a solid lubricant to the surface of the image carrier You In the image forming apparatus and a lubricant applying means, the toner is fine silica particles having an average particle size of 0.03~1μm the base particles the surface of the toner is a toner obtained by wet externally added, the Euler belt method The image forming apparatus is characterized in that the static friction coefficient of the image carrier with respect to the medium-quality high-quality paper is 0.1 to 0.4.

The present invention further provides the image forming apparatus , wherein the toner is obtained by performing a heat treatment after wet external addition .
The present invention further relates to a toner obtained by wet-adding the toner by adding a surfactant having a polarity different from the polar group on the surface of the toner base particles and inorganic fine particles in an aqueous medium after the emulsion dispersion step. Ru der image forming apparatus characterized by certain.

The present invention is the image forming apparatus , wherein the toner further includes a dry external additive of a fluidizing agent.
The present invention further provides the image forming apparatus , wherein the image carrier contains a fluorine resin or a silicon resin in the surface layer.
The present invention further provides the image forming apparatus , wherein the solid lubricant is zinc stearate.

  According to the present invention, it is possible to prevent the toner from slipping through the cleaning blade, and the transfer residual toner on the photoconductor adheres to the photoconductor or the photoconductor and the charging roller to cause a filming phenomenon. An image forming apparatus that suppresses and prints a high-quality image can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings. The following description is an example of the best mode of the present invention, and it is easy for a person skilled in the art to make other embodiments within the scope of the claims by making changes and modifications within the scope of the claims. However, this does not limit the scope of the claims.

FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 1 is an overall configuration diagram showing an example in which the present invention is applied to a full-color small printer. In an image forming apparatus main body (hereinafter, simply referred to as “apparatus main body”) 1, image forming units 2A, 2B, 2C, and 2D having four photosensitive members as image carriers are connected to the apparatus main body 1. Are detachably attached. A transfer device 3 in which a transfer belt 31 is rotatably mounted in a direction indicated by an arrow A between a plurality of rollers is disposed in the approximate center of the device body 1.
The photosensitive member 5 provided in each of the image forming units 2A, 2B, 2C, and 2D is disposed so as to contact the upper surface of the transfer belt 31. In correspondence with the image forming units 2A, 2B, 2C, and 2D, developing devices 10A, 10B, 10C, and 10D having different toner colors are arranged.
The image forming units 2A, 2B, 2C, and 2D are units having the same configuration, the image forming unit 2A forms an image corresponding to magenta, and the image forming unit 2B forms an image corresponding to cyan. The image forming unit 2C forms an image corresponding to the yellow color, and the image forming unit 2D forms an image corresponding to the black color.

The writing unit 6 is disposed above the image forming units 2A, 2B, 2C, and 2D, and the duplex unit 7 is disposed below the transfer belt 31. This small printer is equipped with a reversing unit 8 on the left side of the apparatus main body 1 for reversing and ejecting the transfer paper after image formation or transporting it to the duplex unit 7.
The writing unit 6 is arranged in four laser diode (LD) light sources prepared for each color, a set of polygon scanners composed of six polygon mirrors and a polygon motor, and the route of each light source. It is composed of a lens such as an fθ lens or a long cylindrical lens, or a mirror. Laser light emitted from the laser diode is deflected and scanned by a polygon scanner and irradiated onto the photosensitive member 5.
The duplex unit 7 includes a pair of conveyance guide plates 45a and 45b and a pair of (four sets in this example) conveyance rollers 46. In the double-sided image formation mode in which an image is formed on both sides of a transfer sheet, The transfer sheet having an image formed on one side, conveyed to the reversal conveyance path 54 of the reversing unit 8 and switched back is received and conveyed toward the paper feeding unit.

The reversing unit 8 includes a plurality of paired transport rollers 46 and a plurality of paired transport guide plates 45. As described above, the reversing unit 8 reverses the transfer paper when forming a double-sided image to the double-sided unit 7. It carries out functions such as unloading, discharging the image-formed transfer paper out of the machine in the same orientation, or inverting the front and back and discharging it out of the machine. Separating sheet feeding units 55 and 56 for separating and feeding the transfer sheets one by one are provided in the sheet feeding unit in which the sheet feeding cassettes 11 and 12 are provided.
Between the transfer belt 31 and the reversing unit 8, there is provided a fixing device 9 for fixing the image of the transfer paper onto which the image has been transferred. A reverse discharge path 20 is formed on the downstream side of the fixing device 9 in the transfer sheet conveyance direction, and the transfer sheet conveyed there can be discharged onto a discharge tray 26 by a discharge roller pair 25. .
In addition, in the lower part of the apparatus main body 1, paper feeding cassettes 11 and 12 that can store transfer papers of different sizes in two upper and lower stages are arranged. Further, a manual feed tray 13 is provided on the right side surface of the apparatus main body 1 so as to be openable and closable in the direction indicated by the arrow B, and the manual feed tray 13 is opened so that manual feeding can be performed therefrom.

  Next, the operation of the image forming apparatus in image formation will be described. When the image forming operation is started, each photoconductor rotates in the clockwise direction in FIG. Then, the surface of each photoconductor 5 is uniformly charged by the charging roller 141. Then, laser light corresponding to a magenta image is written to the photoconductor 5 of the image forming unit 2 by the writing unit 6, and laser light corresponding to a cyan image is applied to the photoconductor 5 of the image forming unit 2B. The 2C photoconductor 5 is irradiated with a laser beam corresponding to a yellow image, and the photoconductor 5 of the image forming unit 2D is irradiated with a laser beam corresponding to a black image, respectively, and a latent image corresponding to the image data of each color. Are formed respectively. Each latent image reaches the position of the developing devices 10A, 10B, 10C, and 10D by the rotation of the photosensitive member 5, and is developed with the toners of magenta, cyan, yellow, and black, and a four-color toner image is obtained. Become.

  On the other hand, the transfer paper is fed from the paper feed cassettes 11 and 12 by the separation paper feed unit, and the toner formed on each photoconductor 5 by the registration roller pair 59 provided immediately before the transfer belt 31. It is conveyed at the same timing as the image. The transfer paper is charged with a positive polarity by a paper suction roller 58 disposed near the entrance of the transfer belt 31, and is thereby electrostatically attracted to the surface of the transfer belt 31. The transfer paper is conveyed while being adsorbed to the transfer belt 31, and magenta, cyan, yellow, and black toner images are sequentially transferred to form a four-color superimposed full-color toner image. . The transfer paper is heated and pressed by the fixing device 9 to melt and fix the toner image, and then passes through a paper discharge system corresponding to the designated mode to the paper discharge tray 26 at the top of the apparatus main body 1. When the paper is reversed, discharged straight from the fixing device 9 and straightly discharged through the reversing unit 8, or when the double-sided image forming mode is selected, the reversing conveyance path in the reversing unit 8 is set. After being fed in, it is switched back and transported to the duplex unit 7, and is fed again from there and after the image is formed on the back surface in the image forming unit provided with the image forming units 2 A, 2 B, 2 C, and 2 D Discharged.

On the other hand, the photosensitive member 5 separated from the transfer belt 31 continues to rotate as it is, and the brush roller 161 applies the lubricant scraped off from the molded lubricant 162 to the photosensitive member 5.
In the subsequent image formation, the above-described image forming process is repeated. However, the lubricant film formed on the photoconductor 5 is very thin, so that charging by the charging device 14 is not hindered. Thereafter, the toner image developed again on the photosensitive member 5 is transferred to the transfer paper adsorbed on the transfer belt 31.

The developing devices 10A, 10B, 10C, and 10D include a developing roller that faces the photoreceptor 5, a screw that conveys and stirs the developer, a toner concentration sensor, and the like. The developing roller is composed of an outer rotatable sleeve and an inner magnet. In accordance with the output of the toner density sensor, toner is supplied from the toner supply device. In this embodiment, a two-component developer composed of toner and carrier is used as the developer.
The carrier is generally composed of the core material itself, or a carrier provided with a coating layer on the core material. The core material of the resin-coated carrier that can be used in the present invention is ferrite or magnetite. The particle size of the core substance is 20 to 65 μm, preferably about 30 to 60 μm. As the resin used for forming the carrier coating layer, a styrene resin, an acrylic resin, a fluororesin, a silicone resin, a mixture thereof, or a copolymer can be used. As a method for forming the coating layer, a resin may be applied to the surface of the carrier core material particles by a spraying method, a dipping method, or the like, as in the conventional case.

FIG. 2 is a schematic diagram showing the configuration of the image forming unit. As shown in FIG. 2, the image forming units 2A, 2B, 2C, and 2D include a photoconductor 5 on which an electrostatic latent image is formed, a charging device 14 that charges the surface of the photoconductor 5, and the photoconductor 5 And a cleaning device 15 for cleaning the surface of the substrate.
The photoreceptor has a friction coefficient of 0.1 to 0.4 and may be either inorganic or organic. As a means for reducing the friction coefficient, either or both of a method of containing a friction coefficient reducing substance in the surface layer and a method of applying a lubricant to the surface can be used.
Examples of the friction coefficient reducing substance to be included in the surface layer include ethylene tetrafluoride resin, ethylene trifluoride chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, and fluorinated ethylene chloride resin. Fluorine-based resin, silicon-based resin, various waxes and the like can be mentioned.
Here, the friction coefficient of the photosensitive member 5 was measured by the Euler belt method as follows. In this case, medium-quality high-quality paper as a belt is stretched around the drum circumference ¼ of the photosensitive member 5 so that the paper is in the longitudinal direction, and a load of, for example, 0.98 N (100 gr) is applied to one of the belts. Then, install a force gauge on the other side, pull the force gauge, and read the load at the time when the belt moves, and the friction coefficient μs = 2 / π × 1n (F / 0.98) (where μ is the coefficient of static friction) , F: measured value). Note that the coefficient of friction of the photoconductor 5 in the image forming apparatus 1 is a value when a steady state is obtained by image formation. This is because the coefficient of friction of the photosensitive member 5 is affected by the other apparatus provided in the image forming apparatus 1 and therefore changes from the value of the coefficient of friction immediately after the image formation. However, the value of the friction coefficient becomes a substantially constant value by forming about 1,000 images on A4 size recording paper. Therefore, the coefficient of friction referred to here means the coefficient of friction when it becomes constant in the steady state.

  The charging roller 141 in the charging device 14 is conductive or semiconductive, and applies a DC and / or AC voltage to apply a charge on the photoconductor 5 to charge the photoconductor 5. A charging roller cleaning brush 142 for cleaning the roller surface is in contact with the charging roller 141. In this embodiment, since there is no contact, the applied bias is obtained by superimposing an AC voltage on a DC voltage in consideration of a variation in charging potential due to a minute gap variation, discharge stability, and the like.

The cleaning device 15 includes a cleaning blade 151 that cleans untransferred toner on the surface of the photoconductor 5, a support 154 that supports the cleaning blade 151, a blade pressure spring 152 that adjusts the contact pressure of the cleaning blade 151, and the cleaning blade 151. A rotation fulcrum 153 that is rotated by the contact pressure is provided.
The lubricant application device 16 includes a brush-like roller 161 for applying a lubricant, a lubricant molded body 162 in which the lubricant is molded into a box shape, a brush-like roller scraper 158 for separating toner adhering to the brush-like roller, and a lubricant. A bar pressure spring 163 that adjusts the pressure to be pressed against the brush-like roller of the molded body 162 is provided.

The contact method of the cleaning blade 151 may be either a counter method or a trailing method. In particular, a counter system is preferable. Even if the contact pressure with respect to the photoconductor 5 is small, the cleaning property is high and the photoconductor 5 is less worn.
The cleaning blade 151 preferably has a hardness (JIS-A) in the range of 65 to 85 °. If the hardness is less than 65, the cleaning blade 151 is greatly deformed and it becomes difficult to clean the toner or the like. If the hardness exceeds 85, the photoconductor 5 is abraded and the life of the image forming apparatus is shortened. In addition, if the impact resilience at 10 ° C. to 40 ° C. is 40% or less, the cleaning blade 151 is less likely to cause blade noise and chatter. Further, the wear of the photosensitive member 5 is also reduced. Since the rebound resilience is small, it is considered that so-called stick-slip at the contact portion of the photoconductor 5 is reduced and wear is reduced. Further, if the bending stiffness at a distance of 5 mm from the fulcrum when the cleaning blade 151 is bent 5 degrees is 300 mN or more, the cleaning property is improved. When the bending stiffness is low, the contact pressure of the portion where the cleaning blade 151 contacts the photoreceptor 5 is lowered when the contact is made under the same condition, and the force for preventing the toner from slipping is reduced. Further, the cleaning blade 151 in the cleaning device of the present invention is fixed or integrally formed with the support plate 154 in order to maintain a uniform contact angle and contact pressure.

  Further, the cleaning device 15 contacts the lubricant molded body 162 to scrape off the lubricant and supply the brush-like roller 161 to be supplied to the surface of the photosensitive member 5, and the brush-like roller for removing the toner attached to the brush-like roller 161. A scraper 158 and a pressure spring 163 that presses the lubricant molded body 162 against the brush roller 161 with a predetermined pressure are provided. Examples of the lubricant of the molded lubricant 162 include lead oleate, zinc oleate, copper oleate, zinc stearate, cobalt stearate, iron stearate, copper stearate, zinc palmitate, copper palmitate, linolene. Fatty acid metal salts such as zinc acid, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polytrifluorochloroethylene, dichlorodifluoroethylene, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-oxafluoropropylene Fluorine-based resins such as copolymers are listed. In particular, a metal stearate having a large effect of reducing the friction of the photoreceptor 5 and further zinc stearate are more preferable. As the molded lubricant 162, a product obtained by melting and solidifying a fatty acid metal salt such as zinc stearate into a rod shape can be used. The brush-like roller 161 has a shape extending in the axial direction of the photoreceptor 5. The pressure spring 163 is urged against the brush-like roller 161 so that almost all of the lubricant molding 162 can be used up. Since the lubricant molded body 162 is a consumable product, its thickness decreases with time, but since it is pressurized by the pressure spring 163, the lubricant is scraped off by always contacting the brush-shaped roller 161, Thereafter, the photosensitive member 5 is supplied and applied. These lubricants are fixed and brought into contact with the brush-like roller 161. When adjusting the lubricant application amount, the application amount to the photoconductor 5 can be adjusted by a pressure spring 163 which is a spring material.

  At this time, the brush-like roller 161 is disposed so as to rub against the cleaning blade 151. As a result, the cleaning blade 151 cleans, and the toner collected at the tip of the cleaning blade 151 is scraped off by the brush-like roller 161 that applies the lubricant, and is moved to the toner conveying auger 155 side by the brush-like roller 161. The waste toner is ejected from the brush by the roller scraper 158 and separated, and the waste toner collected by rotating the toner transport auger 155 is transported to a waste toner storage unit (not shown). To the cleaning device 15, the toner cleaned by the cleaning blade 151 was transported by a brush or film that transports the cleaning device 15 into the cleaning device 15. The mechanism can be arranged in the cleaning device 15 and the structure can be simplified.

The brush-shaped roller 161 can use fibers selected from polyamide resins such as styrene resin, acrylic resin, polyester resin, fluorine resin, and nylon. In particular, a polyamide resin and a polyester resin that are resistant to wear are good, and it is preferable that the conductive powder is not contained and that the insulating property be maintained. Specifically, the electric resistance is set to 10 ¹² Ωcm or more. In the case of conductivity, the charged toner is attracted to the brush with a mirror image force, so that it is difficult to separate even with the brush-shaped roller scraper 158. By making the brush insulative, the toner from the cleaning blade 151 can be easily scraped off and separated by the brush-shaped roller scraper 158, so that the cleaning toner can be quickly collected. Stable cleaning is possible. In addition, the toner scraped off by the brush-like roller 161 finely scrapes off the lubricant from the lubricant molded body 162 and applies the lubricant to the cleaning blade 151 or the photoreceptor 5. By uniformly applying the lubricant, it is possible to suppress the occurrence of poor cleaning and to prevent background stains.

  Further, the brush-like roller 161 is rotated in the same direction at a portion in contact with the photoreceptor 5. By rotating in this direction, the lubricant adhering to the brush-like roller 161 can be supplied without giving an impact to the photoreceptor 5. There is no need to form a lubricant film when the brush roller 161 supplies the photosensitive member 5, and the lubricant supplied on the photosensitive member 5 forms a lubricant film by the pressing force of the cleaning blade 151. . Therefore, it is preferable here to rotate in the same direction in order to supply without impact. Furthermore, the peripheral speed ratio between the brush roller 161 and the photosensitive member 5 (photosensitive member peripheral speed / brush roller peripheral speed) is preferably in the range of 0.8 to 1.2. When the peripheral speed ratio is less than 0.8, the supply amount of the lubricant decreases, and when it exceeds 1.2, the photoreceptor 5 may be damaged by impact, and the life of the photoreceptor 5 may be shortened. Further, in order to supply the lubricant from the brush to the photoconductor 5 with a small impact, it is further preferable that the ratio is in the range of 1.0 to 1.1.

It is found that the toner particles close to a spherical shape with a high degree of circularity are inferior in blade cleaning properties because the toner rotates and slips through the blade, making the toner itself difficult to rotate and rotating the toner. The problem was overcome by weakening the power to arrive at the present invention.
First, as a means for suppressing rotation of the toner itself, an effect of improving cleaning properties was obtained by externally adding fine particles to the toner surface by a wet method. It seems that fine particles move easily on the toner surface in dry external addition, but the effect was small. In addition, it is considered that the dry external addition also has an influence that the particles are difficult to adhere to the toner surface as the particle size of the fine particles increases. Especially in the case of wet external addition, when acidic groups or basic groups are present on the surface of toner particles made in an aqueous medium such as suspension polymerization method, emulsion polymerization method, polymer suspension method, surface in the presence of fine particles. It was confirmed that when a surfactant having a polarity opposite to that of the functional group was added, the fine particles adhered uniformly and firmly to the toner particle surface, and the effect of improving the cleaning property was enhanced.
Further, at that time, it was confirmed that the same effect was obtained even when a nonionic or amphoteric surfactant was used as the surfactant of opposite polarity.

When polar functional groups are present on the toner surface, the toner particles are stably dispersed in water by being charged with the same polarity. At that time, if a surfactant with reverse polarity is added, it not only adsorbs on the surface of the toner particles but also adsorbs on the inorganic fine particles present in the aqueous medium, is charged with the reverse polarity, and is electrostatically attracted to the surface of the toner particles. It is thought that it can move and adhere uniformly.
Further, it was found that the inorganic fine particles once adhered are not easily detached even after drying, but are more strongly adhered by performing a heat treatment in an aqueous medium after the adhesion.
Although the size of the fine particles depends on the particle size of the toner base, 0.03 to 1 μm particles are good. When the particle size is smaller than 0.03 μm, the effect of improving the cleaning property is clearly reduced.
After drying the treated particles, to further enhance fluidity, chargeability, etc., by dry mixing with a fluidizing agent such as the same inorganic fine particles used in an aqueous medium, different inorganic fine particles or organic fine particles It has also been found that the toner flow characteristics and charging characteristics can be reinforced.

Next, it is found that the action of rotating the toner is caused by friction with the photoconductor 5, and by reducing the friction coefficient of the photoconductor 5, the rotation is suppressed and the blade cleaning property of the toner with high circularity is improved. I was able to.
Thus, by using both the means for suppressing the rotation of the toner itself and the means for reducing the rotational force of the toner, reliable cleaning can be performed. Insufficient cleaning occurred when the hardness of the cleaning blade increased at low temperatures.

Next, the toner used in the present invention will be described.
(Method for producing toner base particles having a circularity of 0.93 or more)
The circularity can be measured as an average circularity by a flow type particle image analyzer FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd.). As a specific measuring method, 0.1 to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and further measurement is performed. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is obtained by performing dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and measuring the shape and distribution of the toner with the above apparatus at a dispersion concentration of 3000 to 10,000 / μl. .

(1) Suspension polymerization method Emulsification described later in an aqueous medium in which a colorant, a release agent and the like are dispersed in an oil-soluble polymerization initiator and a polymerizable monomer, and a surfactant and other solid dispersant are contained. Emulsified and dispersed by the method. Thereafter, after carrying out a polymerization reaction to form particles, the inorganic fine particle adhesion treatment in the present invention may be performed. At that time, it is preferable to treat the toner particles from which the surplus surfactant and the like are removed by washing. As a polymerizable monomer, acrylic acid, methacrylic acid, α - cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride and other acids, acrylamide, methacrylamide, diacetone Functional groups can be introduced on the surface of toner particles by using acrylamide or some of these methylol compounds, pinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethylene imine, acrylates having amino groups such as dimethylaminoethyl methacrylate, and methacrylates. .
Further, by selecting a dispersant having an acid group or a basic group as a dispersant to be used, the dispersant can be adsorbed and left on the particle surface to introduce a functional group.

(2) Emulsion polymerization aggregation method A water-soluble polymerization initiator and a polymerizable monomer are emulsified in water using a surfactant, and a latex is synthesized by an ordinary emulsion polymerization technique. Separately, a dispersion in which a colorant, a release agent and the like are dispersed in an aqueous medium is prepared, and after mixing, the toner is aggregated to a toner size and heat-fused to obtain a toner. Thereafter, the same treatment as that for the suspension polymerization particles may be performed. A functional group can be introduced on the surface of the toner particles by using a latex similar to the monomer that can be used for suspension polymerization.

(3) Polymer suspension method The aqueous medium used in the present invention may be water alone, or a solvent miscible with water may be used in combination. Examples of the miscible solvent include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methylcellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.) and the like.

  In the oil phase of the toner composition, a colorant such as resin, prepolymer and pigment, a release agent, a charge control agent and the like are dispersed in a volatile solvent. In order to lower the viscosity of the oil phase and make it emulsifiable, a volatile solvent in which the polyester resin or prepolymer is soluble is used. The solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal. Examples of the solvent include 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 preferable. In addition, the toner shape can be further adjusted by using a solvent that can be dissolved in an aqueous medium such as alcohol or water. The amount of solvent used with respect to 100 parts of the toner composition is usually 10 to 900 parts.

In order to introduce a functional group into the toner particles, in the case of a copolymer with a monomer having a functional group used for suspension polymerization or a polyester resin, the functional group of an acid group is used as an acid monomer. It can be obtained by using one having three or more or esterifying the terminal hydroxyl group of the obtained polyester resin with a compound having a plurality of acid groups.
The toner particles may be formed by reacting, for example, a dispersion in a volatile organic solvent composed of a prepolymer having an isocyanate group and another toner composition with an amine in an aqueous medium. Examples of a method for stably forming a dispersion composed of a prepolymer and a toner composition in an aqueous medium include a method in which a composition of a toner raw material composed of a prepolymer is added to an aqueous medium and dispersed by shearing force. It is done. Colorant, colorant masterbatch, release agent, charge control agent, polyester resin, etc. which are prepolymer and other toner composition (hereinafter referred to as toner raw material) are mixed when forming a dispersion in an aqueous medium. However, it is more preferable to mix the toner raw materials in advance to form an oil phase, and then add and disperse the mixture in the aqueous medium. For the dispersion, an ordinary agitating mixer, more preferably a homogenizer having a high-speed rotating body and a stator, a high-pressure homogenizer, a disperser using a medium such as a ball mill, a bead mill, a sand mill, or the like is used. In the present invention, other toner materials such as a colorant, a release agent, and a charge control agent do not necessarily have to be mixed when forming particles in an aqueous medium, but after the particles are formed. , May be added. For example, after forming particles containing no colorant, the colorant can be added by a known dyeing method.

The dispersion method is not particularly limited, and known equipment such as a low-speed shear type, a high-speed shear type, a friction type, a high-pressure jet type, and an ultrasonic wave can be applied. In order to make the particle size of the dispersion 2 to 20 μm, a high-speed shearing type is preferable. The emulsifier having rotating blades is not particularly limited, and any emulsifier and disperser that are generally commercially available can be used. For example, Ultra Thalax (manufactured by IKA), Polytron (manufactured by Kinematica), TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), Ebara Milder (manufactured by Ebara Corporation), TK pipeline homomixer , TK homomic line flow (manufactured by Special Machine Industries Co., Ltd.), colloid mill (manufactured by Shinko Pantech Co., Ltd.), slasher, trigonal wet pulverizer (manufactured by Mitsui Miike Chemical Co., Ltd.), Cavitron (Eurotech Co., Ltd.) ), Fine flow mill (manufactured by Taiheiyo Kiko Co., Ltd.), and other continuous emulsifiers, CLEARMIX (manufactured by M Technique Co., Ltd.), fill mix (manufactured by Koki Kogyo Co., Ltd.), etc. Etc.
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 10 to 98 ° C. Higher temperatures are preferred in that the dispersion of the prepolymer is low in viscosity and easy to disperse.

The amount of the aqueous medium used is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight, based on 100 parts by weight of the toner composition containing the prepolymer. If the amount is less than 50 parts by weight, the dispersion state of the toner composition is poor, and toner particles having a predetermined particle diameter cannot be obtained. More than 200 0 by weight part is not economical.
In the aqueous medium, a resin solid fine particle such as a soap-free latex may be dispersed as a dispersant in addition to a surfactant as an emulsification dispersion stabilizer. Further, the stabilization of the dispersed droplets may be adjusted with 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 body, such as acrylic acid beta - hydroxyethyl, methacrylate beta - hydroxyethyl, acrylic acid beta - hydroxypropionic building, methacrylate beta - hydroxypropyl, acrylic acid gamma - hydroxypropyl methacrylate gamma - hydroxypropyl, acrylic acid 3- chloro 2-hydroxypropionate building, methacrylic acid 3 - chloro - 2 - hydroxypropyl, diethylene glycol acrylate, diethylene glycol methacrylate, glycerol monoacrylate, glycerol monomethacrylate S. Le, N- methylol acrylamide, N - methylol methacrylamide etc., et chromatography ethers of vinyl alcohol or vinyl alcohol such as vinyl methyl ether, vinyl ethyl ether and 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, pinyl pyridine, vinyl pyrrolidone, vinyl imidazole , Homopolymers or copolymers such as those having a nitrogen atom such as ethyleneimine or its heterocyclic ring, polyoxyethylene, polyoxypropylene , Polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl 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. When a dispersant is used, the dispersant can remain on the surface of the toner particles. However, after the elongation and / or cross-linking reaction, it is better to dissolve and wash away the remaining solid fine particle dispersant. From the aspect, it is preferable.

The elongation and / or crosslinking reaction time is selected depending on the reactivity of the isocyanate group structure of the prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. is there. 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.
In order to remove the organic solvent from the obtained emulsified dispersion, a method can be employed in which the temperature of the entire system is gradually raised and the organic solvent in the droplets is completely evaporated and removed. Alternatively, it is also possible to spray the emulsified dispersion in a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, and to evaporate and remove the aqueous dispersant together. . As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air streams heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used are generally used. Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer or rotary kiln.

When the particle size distribution at the time of emulsification dispersion is wide, and washing and drying processes are performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classification into a desired particle size distribution.
In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Of course, the classification operation may be performed after obtaining the powder as a powder after drying. The unnecessary fine particles or coarse particles obtained can be returned to the kneading step and used for the formation of particles. At that time, fine particles or coarse particles may be wet.
The dispersant used is preferably removed from the obtained dispersion as much as possible, but it is preferable to carry out it simultaneously with the classification operation described above.

(4) Other dry toner production methods The average circularity of 0.95 or more can be obtained by further adjusting the shape of the toner obtained even with a normal kneading and pulverizing toner. For example, the degree of circularity can be increased by applying heat, such as a method of adjusting the shape with a mechanical impact force using a hybridizer, mechanofusion, or the like, or a surffusion system.
In addition, a so-called spray dry method is a method in which a toner material is dissolved and dispersed in a solvent in which a toner binder is soluble, and then a solvent is removed using a spray dry device to obtain a spherical toner, or a spherical shape is obtained by heating in an aqueous medium. However, it is not limited to these.

(Particle adhesion treatment method)
In common with any of these toner manufacturing methods, the inorganic fine particle adhesion treatment can be performed in the liquid. It is preferable to perform this step after the toner particles are formed in water and the used surfactant and the like are removed by washing. Excess surfactant present in water is removed by solid-liquid separation such as filtration and centrifugation, and the resulting cake and slurry are redispersed in an aqueous medium. Further, inorganic fine particles are added and dispersed in the slurry. Inorganic fine particles can be dispersed in an aqueous dispersion in advance. At that time, if dispersed using a surfactant having a reverse polarity, adhesion to the surface of the toner particles is more efficiently performed. In addition, when the inorganic fine particles are hydrophobized and are difficult to disperse in the aqueous dispersion, the inorganic fine particles may be dispersed after the interfacial tension is lowered by using a small amount of alcohol or the like to facilitate wetting.
Thereafter, an aqueous surfactant solution having a reverse polarity is gradually added with stirring. The reverse polarity surfactant is preferably used in an amount of 0.01 to 1% by weight based on the solid content of the toner particles.
By adding a surfactant having a reverse polarity, the charge of the inorganic fine particle dispersion in water is neutralized, and the inorganic fine particles can be aggregated and adhered to the surface of the toner particles. The inorganic fine particles are preferably used in an amount of 0.01 to 5% by weight based on the solid content of the toner particles.
The inorganic fine particles adhered to the toner surface can be fixed to the toner surface by heating the slurry and then prevented from being detached. At that time, it is desirable to heat at a temperature higher than the Tg of the resin constituting the toner. Further, heat treatment may be performed after drying while preventing aggregation.

Moreover, the charge control agent fine particle dispersion may be present in the slurry redispersed for the purpose of reinforcing the chargeability. The charge control agent is usually in the form of a powder, but it is separately used in the aqueous medium by using the surfactant used when the particles are produced in the aqueous medium or the reverse polarity surfactant added for the purpose of imparting the charge. A fine particle dispersion can be obtained by dispersing in the above. By adding a surfactant having a reverse polarity, the charge of the charge control agent fine particle dispersion in water can be neutralized and agglomerated and adhered to the toner particle surface.
The charge control agent is preferably a dispersion having a particle size of 0.01 to 1 μm, and can be used in an amount of 0.01 to 5% by weight based on the solid content of the toner particles.
In addition, the resin fine particle dispersion may be present in the slurry redispersed for the purpose of reinforcing the chargeability. The resin fine particle dispersion is preferably obtained by emulsion polymerization.
By adding a surfactant having a reverse polarity, the charge in the resin fine particle dispersion in water is neutralized, and can be agglomerated and adhered to the toner particle surface. The resin fine particles can be used in an amount of 0.01 to 5% by weight based on the solid content of the toner particles.

(Surfactant)
Examples of the anionic surfactant include alkylbenzene sulfonate, α - olefin sulfonate, and phosphate ester.
Cationic surfactants include amine salts such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, imidazoline, alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoses. Quaternary ammonium salt types such as quinolinium salt and benzethonium chloride are listed.
Nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives, for example, amphoteric interfaces such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine An activator may be used.
The amount of these surfactants used is preferably 0.1 to 10% by weight based on the entire aqueous phase.

(Fluorosurfactant)
In the present invention, the use of a fluorosurfactant as the reverse polarity surfactant can further improve the charging performance, particularly the charge rise-up property.
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- [omega-fluoroalkyl (C6 to C11). Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [omega-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carboxylic acid and Metal salts, perfluoroalkyl carboxylic acids (C7 to C13) and their metal salts, perfluoroalkyl (C4 to C12) sulfonic acids and their metal salts, perfluorooctane sulfonic acid diethanolamide, N - propyl-N- (2 hydroxy ethyl) Perfluorooctanesulfonamide, 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 Taikin Kogyo Co., Ltd.), Mega-Fac F-ll0, F-120, F-113, F-191, F-812, F-833 (Dainippon Ink Co., Ltd.), Xtop EF- 102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fagento F-100, F150 (manufactured by Neos).

As the cationic surfactants, aliphatic primary to have a fluoroalkyl group, secondary or secondary amine acids, aliphatic quaternary ammonium salts such as perfluoroalkyl (C6 ~ C10) sulfonamide propyl trimethyl ammonium salt, Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass), Florard FC-135 (Sumitomo 3M), Unidyne DS-202 (Daikin Industries) ), 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.
In particular, by using the fluorine-containing quaternary ammonium salt compound represented by the general formula (1), it is possible to obtain a stable developer with little change in charge amount when the environment changes.

^{(Wherein, X, Y, R 1 ~} R 4, r and s represent the following, respectively.
X represents —SO ₂ — or —CO—, R ¹ , R ² , R ³ and R ⁴ represent a hydrogen atom, a lower alkyl group having 1 to 10 carbon atoms or an aryl group, and Y represents I or Br. , r, s is shows the integer of 1 to 20. )

(Fine particles)
As the inorganic fine particles for adhesion treatment in an aqueous medium and if necessary dry mixing thereafter, the primary particle diameter is preferably 5 nm to 2 μm, and the specific surface area by the BET method is 20 to 500 m ² / g. Preferably there is. The use ratio of the inorganic fine particles is preferably 0.01 to 5% by weight of the toner particles, and particularly preferably 0.01 to 2.0% by weight. 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, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Organic fine particles include polymer fine particles such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, methacrylic acid ester and acrylate copolymer, polycondensation system such as silicone, benzoguanamine and nylon, thermosetting Polymer particles made of a functional resin. In order to improve the cleaning property, relatively large particles of 0.03 to 1 μm are effective, and therefore more preferable.

Such inorganic fine particles can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .
Other toner constituents The following functional materials can be used as toner constituents as required.

(Charge control agent)
Any known charge control agent can be used. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified) Quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Nitronine-based dye Bontron 03, quaternary ammonium salt Bontron P-51, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E- 84, E-89 of a phenol-based condensate (manufactured by Orient Chemical Industry Co., Ltd.), TP-302 of a quaternary ammonium salt molybdenum complex, TP-415 (manufactured by Hodogaya Chemical Industry Co., Ltd.), quaternary ammonium Copy charge PSY VP2038 of salt, copyable-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 (Manufactured by Nippon Carlit), copper phthalocyanine, perylene, quinacridone Azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.

(Charge control resin fine particles)
Polymer fine particles, for example, resin fine particle dispersions obtained by soap-free emulsion polymerization, suspension polymerization or dispersion polymerization are preferred. In particular, polystyrene copolymerized with a monomer having a carboxyl group such as methacrylic acid, a copolymer obtained by emulsion polymerization or dispersion polymerization of fluorine-based methacrylate ester or fluorine-based acrylic ester, silicone, benzoguanamine, nylon, etc. And polymer fine particles of a polycondensation system and a thermosetting resin.

(Solid fine particle dispersant)
The solid fine particle dispersant as an emulsification stabilizer is a solid that is hardly soluble in water in an aqueous medium, and is preferably fine particles having an average particle diameter of 0.01 to 1 μm.
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, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
More preferably, tricalcium phosphate, calcium carbonate, colloidal titanium oxide, colloidal silica, hydroxyapatite and the like can also be used. In particular, hydroxyapatite synthesized by reacting sodium phosphate and calcium chloride in water under a basic condition is preferable. Others Organic solid fine particle dispersants are copolymerized with monomers having a carboxyl group such as fine crystals of low molecular weight organic compounds and polymer fine particles such as soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization. Polystyrene particles such as polystyrene, methacrylic acid ester, acrylic acid ester copolymer, polycondensation systems such as silicone, benzoguanamine, and nylon, and thermosetting resin.

(Compound having an isocyanate group at the end: Prepolymer)
Examples of the polyester prepolymer (A) having an isocyanate group include a product obtained by further reacting a polyester having an active hydrogen group with a polyisocyanate (3), which is a polycondensate of polyol (1) and polycarboxylic acid (2). Can be mentioned. Examples of the active hydrogen group possessed by the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are preferred.

  Examples of the polyol (1) include a diol (1-1) and a tri- or higher valent polyol (1-2). (1-1) alone or (1-1) and a small amount of (1-2) Mixtures are preferred. Diol (1-1) includes alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the alicyclic diol; bisphenol And alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, 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. The trihydric or higher polyol (1-2) includes 3 to 8 or higher polyhydric aliphatic alcohols (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 polycarboxylic acid (2) include dicarboxylic acid (2-1) and trivalent or higher polycarboxylic acid (2-2). (2-1) alone and (2-1) with a small amount of ( The mixture of 2-2) is preferred. Dicarboxylic acid (2-1) includes alkylene dicarboxylic acid (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acid (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acid (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 polycarboxylic acid (2-2) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (trimellitic acid, pyromellitic acid, and the like). In addition, as polycarboxylic acid (2), you may make it react with polyol (1) using the acid anhydride or lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) of the above-mentioned thing.
The ratio of the polyol (1) and the polycarboxylic acid (2) is usually 2/1 to 1/1, preferably 1. as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. 5/1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

Examples of the polyisocyanate (3) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); aromatic Diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; polyisocyanates such as phenol derivatives, oximes, caprolactam And a combination of two or more of these.
The ratio of the polyisocyanate (3) is usually 5/1 to 1/1, preferably 4 /, as the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. If the molar ratio of [NCO] is less than 1, the urea content in the modified polyester will be low, and the hot offset resistance will deteriorate. The content of the polyisocyanate (3) component in the prepolymer (A) having an isocyanate group at the terminal is usually 0.5 to 40% by weight, preferably 1 to 30% by weight, more preferably 2 to 20% by weight. It is. If it is less than 0.5% by weight, 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% by weight, the low-temperature fixability deteriorates.
The number of isocyanate groups contained per molecule in the prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. It is. If the number is less than 1 per molecule, the molecular weight of the urea-modified polyester to be produced becomes low, and the hot offset resistance deteriorates.

As amines (B), diamine (B1), trivalent or higher polyamine (B2), aminoalcohol (B3), aminomercaptan (B4), amino acid (B5), and amino acids B1-B5 blocked (B6) etc. are mentioned. Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane, Isophorone diamine etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine etc.) and the like. Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of B1 to B5 blocked amino groups (B6) include ketimine compounds and oxazoline 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.
Furthermore, if necessary, the molecular weight of the urea-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The ratio of amines (B) is the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). The ratio 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 more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated. In the present invention, the polyester modified with a urea bond 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.

(Polyester resin)
In the present invention, unmodified polyester (C) can be contained as a toner binder component together with the prepolymer (A) and amines (B). By using (C) in combination, the low-temperature fixability and the glossiness when used in a full-color device are improved, which is preferable to single use. Examples of (C) include the same polycondensates of polyol (1) and polycarboxylic acid (2) as the polyester component of prepolymer (A), and the preferred one is also a polyester component of prepolymer (A). It is the same. (C) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, and may be modified with, for example, a urethane bond. It is preferable from the viewpoints of low temperature fixability and hot offset resistance that at least a part of the reactants (A) and (B) and (C) are compatible. Accordingly, the polyester component (A) and (C) preferably have similar compositions. When (C) is contained, the weight ratio of (A) to (C) is usually 5/95 to 80/20, preferably 5/95 to 30/70, more preferably 5/95 to 25/75, Particularly preferred is 7/93 to 20/80. If the weight ratio of (A) is less than 5%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.
The peak molecular weight of (C) is usually 1000-30000, preferably 1500-10000, more preferably 2000-8000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 10,000, low-temperature fixability will deteriorate. The hydroxyl value of (C) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The acid value of (C) is usually 1 to 30, preferably 5 to 20. By having an acid value, it tends to be negatively charged.

In the present invention, the glass transition point (Tg) of the toner binder is usually 50 to 70 ° C., preferably 55 to 65 ° C. If the temperature is less than 50 ° C., the heat-resistant storage stability of the toner is deteriorated. Due to the coexistence of the urea-modified polyester resin that is the reaction product of (A) and (B), the dry toner of the present invention has good heat-resistant storage stability even when the glass transition point is low, as compared with known polyester toners. Show a trend. As the storage elastic modulus of the toner binder, the temperature (TG ′) at which 10000 dyne / cm ² is obtained at a measurement frequency of 20 Hz is usually 100 ° C. or higher, preferably 110 to 200 ° C. If it is less than 100 ° C., the resistance to hot offset deteriorates. As the viscosity of the toner binder, the temperature (Tη) at 1000 poise at a measurement frequency of 20 Hz is usually 180 ° C. or lower, preferably 90 to 160 ° C. If it exceeds 180 ° C., the low-temperature fixability deteriorates. That is, from the viewpoint of achieving both low temperature fixability and hot offset resistance, TG ′ is preferably higher than Tη. In other words, the difference between TG ′ and Tη (TG′−Tη) is preferably 0 ° C. or higher. More preferably, it is 10 degreeC or more, Most preferably, it is 20 degreeC or more. The upper limit of the difference is not particularly limited. Further, from the viewpoint of achieving both heat-resistant storage stability and low-temperature fixability, the difference between Tη and Tg is preferably 0 to 100 ° C. More preferably, it is 10-90 degreeC, Most preferably, it is 20-80 degreeC.

(Coloring agent)
As the colorant of the present invention, 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 , Fais red, parachlorol Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine B, 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, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake , Thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone , Polyazo red, chrome vermillion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue rake, peacock blue rake, Victoria blue rake, metal free phthalocyanine blue, phthalocyanine blue, fast sky blue, in Dunslen 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, Chrome Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake Phthalocyanine green, anthraquinone green, titanium oxide, zinc white, lithobon 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 used in the present invention can also be used as a master batch combined with a resin. As the binder resin to be kneaded together with the production of the masterbatch or the masterbatch, in addition to the modified and unmodified polyester resins mentioned above, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, and polymers of substituted products thereof; Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α- Chloromethyl methacrylate copolymer, Tylene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-malein Styrene copolymers such as acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, poly Acrylic resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. The

  This master batch can be obtained by mixing and kneading a resin for a master batch and a colorant under a high shear force to obtain a master batch. At this time, an organic solvent can be used to enhance the interaction between the colorant and the resin. Also, a so-called flushing method called watering paste containing water of a colorant is mixed and kneaded together with a resin and an organic solvent, and the colorant is transferred to the resin side to remove moisture and organic solvent components. Since it can be used as it is, it does not need to be dried and is preferably used. For mixing and kneading, a high shear dispersion device such as a three-roll mill is preferably used.

(Release agent)
Further, a wax may be contained together with the toner binder and the colorant. Known waxes can be used as the wax of the present invention, such as polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax, sasol wax, etc.); carbonyl group-containing wax, etc. It is done. Of these, carbonyl group-containing waxes are preferred. Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18. -Octadecandiol diol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylenediamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearylamide, etc.) And dialkyl ketones (such as distearyl ketone). Among these carbonyl group-containing waxes, polyalkanoic acid esters are preferred. The melting point of the wax of the present invention is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. A wax having a melting point of less than 40 ° C. has an adverse effect on heat resistant storage stability, and a wax having a melting point of more than 160 ° C. tends to cause a cold offset when fixing at a low temperature. Further, the melt viscosity of the wax is preferably 5 to 1000 cps, more preferably 10 to 100 cps as a measured value at a temperature 20 ° C. higher than the melting point. Waxes exceeding 1000 cps have poor effects for improving hot offset resistance and low-temperature fixability. The content of the wax in the toner is usually 0 to 40% by weight, preferably 3 to 30% by weight.

(Fluidizer, dry external additive)
The fluidity, developability, and chargeability of the colored particles obtained in the present invention can be sufficiently effective only by the adhesion and fixation of the external additive in an aqueous system, but in order to assist this, it is possible to mix them dry. it can. As the external additive for this purpose, the fine particles mentioned above in the wet adhesion treatment can be used.
In order to improve fluidity and developability, relatively small particles of 0.01 to 0.05 μm are more preferable because they are effective. Further, such a fluidizing agent is preferably subjected to a surface treatment with a hydrophobizing agent.
Examples of hydrophobizing agents include silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, and modified silicone oils. Can be mentioned.
Examples of cleaning improvers for removing the developer after transfer remaining on the photoreceptor 5 or the primary transfer medium include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, such as polymethyl methacrylate fine particles and polystyrene fine particles. Examples thereof include polymer fine particles produced by soap-free emulsion polymerization. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.

(Carrier for two components)
When the toner of the present invention is used for a two-component developer, it may be used by mixing with a magnetic carrier, and the content ratio of the carrier and the toner in the developer is 1 to 10 wt. Part is preferred. As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, magnetic resin carrier having a particle diameter of about 20 to 200 μm can be used. Examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene acrylic copolymer resins, Halogenated olefin resin such as vinyl, polyester resin such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoro Propylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinylidene fluoride And fluoro such as terpolymers of non-fluoride monomers including, and silicone resins. Moreover, you may contain electrically conductive powder etc. in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle diameter of 1 μm or less. When the average particle diameter is larger than 1 μm, it becomes difficult to control electric resistance.
The toner of the present invention can also be used as a one-component magnetic toner that does not use a carrier or a non-magnetic toner.

Hereinafter, the present invention will be described in detail by way of examples. In addition, all the description of a part is a weight part.
<Example 1>
(Synthesis of polyester resin)
724 parts of bisphenol A ethylene oxide 2-mole adduct, 276 parts of terephthalic acid and 2 parts of dibutyltin oxide are placed in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe. The condensation reaction was performed, and the reaction was further performed at a reduced pressure of 10 to 15 mmHg for 5 hours to obtain an unmodified polyester having a peak molecular weight of 4800. Thereafter, 10 parts of trimellitic anhydride was added, and the reaction was performed at 200 ° C. for 2 hours under reduced pressure of 10 to 15 mmHg to convert the hydroxyl group at the resin end to a carboxyl group. 100 parts of the obtained resin was dissolved and mixed in 100 parts of ethyl acetate to obtain an ethyl acetate solution of a toner binder. A portion of the mixture was dried under reduced pressure to isolate the polyester resin. The Tg was 62 ° C. and the acid value was 32.

(Synthesis of terminal isocyanate polyester)
724 parts of bisphenol A ethylene oxide 2-mole adduct, 276 parts of isophthalic acid and 2 parts of dibutyltin oxide are placed in a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and reacted at 230 ° C. for 8 hours at normal pressure. The reaction was further carried out at a reduced pressure of 10 to 15 mmHg for 5 hours, followed by cooling to 160 ° C., and 32 parts of phthalic anhydride was added thereto and reacted for 2 hours. Subsequently, it cooled to 80 degreeC and reacted with 188 parts of isophorone diisocyanate in ethyl acetate for 2 hours, and the isocyanate containing polymer was obtained.
(Synthesis of ketimine compounds)
A reaction vessel equipped with a stir bar and a thermometer was charged with 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone, and reacted at 50 ° C. for 5 hours to obtain a ketimine compound. The amine value of this ketimine compound was 418.

(Creation of toner and developer)
In a sealed pot, 200 parts of an ethyl acetate solution of the polyester resin, 5 parts of carnauba wax, and 4 parts of copper phthalocyanine blue pigment were charged, and ball mill dispersion was performed for 24 hours using 5 mmφ zirconia beads. Thereafter, 20 parts of an isocyanate-containing prepolymer in terms of solid content was added and mixed by stirring to obtain a toner composition. In a beaker, 600 parts of ion exchange water, 60 parts of tricalcium phosphate and 3 parts of sodium dodecylbenzenesulfonate were uniformly dissolved and dispersed. Next, while maintaining the internal temperature of the beaker at 20 ° C. and stirring at 14000 rpm with a TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.), it is prepared in an oil phase in which 1 part of a ketimine compound is mixed immediately before emulsification. Thereafter, the mixture was emulsified with stirring for 3 minutes. Next, this mixed liquid was transferred to a flask equipped with a stir bar and a thermometer, and the solvent was removed at 30 ° C. under reduced pressure of 50 mmHg for 8 hours. It was confirmed by gas chromatography that the ethyl acetate in the dispersion was 100 ppm or less. Thereafter, the dispersion was cooled to room temperature, and 120 parts of 35% concentrated hydrochloric acid was added to dissolve tricalcium phosphate. Then, after stirring at room temperature for 1 hour, the operation of separating by filtration and redispersing the obtained cake in distilled water and filtering was repeated 3 times. The obtained cake was further redispersed in distilled water to a solid content of 10% by weight. Meanwhile, 3 parts of hydrophobized silica X-24 (manufactured by Shin-Etsu Chemical Co., Ltd.) was stirred in a solution of 0.2 parts by weight of Footent 310 (manufactured by Neos), 70 parts by weight of ion-exchanged water, and 30 parts by weight of methanol. While adding gradually, a dispersion of silica fine particles was obtained. The resulting silica fine particle dispersion was mixed with the above toner particle dispersion, then stirred for 1 hour at room temperature, filtered and separated, and the resulting cake was dried under reduced pressure at 40 ° C. for 24 hours to obtain a volume. Toner particles having an average particle diameter of 4.8 μm and an average circularity of 0.98 were obtained. According to SEM (scanning electron microscope), about 0.12 μm silica fine particles were uniformly attached to the surface of the obtained toner particles.
With respect to 100 parts by weight of the toner particles, 1.2 parts by weight of hydrophobic silica fine particles (HDK H-2000 manufactured by Hoechst Japan), 0.5 parts by weight of hydrophobic titanium oxide (STT-30A manufactured by Titanium Industry), zinc stearate 0.1 part by weight was dry-added with a Henschel mixer to obtain a cyan toner.
A developer was prepared by mixing 5 parts by weight of the prepared cyan toner and 95 parts by weight of a silicon resin- coated carrier with a blender for 10 minutes.

(Create photoconductor)
By coating and drying an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution in the following order on a φ30 mm aluminum drum in sequence, an undercoat layer of 3.5 μm, 0 A 3 μm charge generation layer and a 22 μm charge transport layer were formed. Next, the protective layer coating solution was applied by spraying to provide a 5 μm protective layer to obtain the electrophotographic photosensitive member of the present invention. The protective layer coating solution was subjected to vibration mill dispersion for 2 hours using φ2 mm zirconia balls.
[Coating liquid for undercoat layer]
Alkyd resin (Beccosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals)
10 parts by weight melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
7 parts by weight Titanium oxide (CR-EL manufactured by Ishihara Sangyo Co., Ltd.) 40 parts by weight Methyl ethyl ketone 200 parts by weight [Coating liquid for charge generation layer]
5 parts by weight of bisazo pigment having the following structure (manufactured by Ricoh)

Polyvinyl butyral (XYHL, manufactured by UCC) 1 part by weight Cyclohexanone 200 parts by weight Methyl ethyl ketone 80 parts by weight [Coating liquid for charge transport layer]
10 parts by weight of polycarbonate resin (Z polycarbonate, viscosity average molecular weight; 50,000, manufactured by Teijin Chemicals Ltd.) 7 parts by weight of low molecular charge transport material having the following structure

Tetrahydrofuran 100 parts by weight 1% silicone oil (KF50-100CS manufactured by Shin-Etsu Chemical Co., Ltd.) Tetrahydrofuran solution 1 part by weight (protective layer)
Lubron L-2 1 part Modiper F210 0.1 part Z Polyca (viscosity average molecular weight 50,000) 9 parts THF 90 parts The surface friction coefficient of the prepared photoreceptor was 0.26.
The surface friction coefficient was measured at a load of 100 g using a Ricoh type 6200Y mesh by the Euler belt method.

(Evaluation of blade cleaning properties)
The developer and the photosensitive member were placed in a color copying machine (Ipsio Color 8100: manufactured by Ricoh), and after running 100,000 sheets with 6000 paper manufactured by Ricoh with a printing ratio of 7%, the temperature was 10 ° C. 10 images with an image occupancy rate of 50% are output continuously in an environment of 15% RH, the 10th image is stopped during development, the toner after the cleaning blade on the photoreceptor is transferred to tape, and the degree of contamination of the tape is 4 Evaluation was made in comparison with a stage sample. Note that the amount of toner after the cleaning blade is small in the order of ◎>○>△> ×. In particular, the evaluation of x is a level at which streaky cleaning defects occur on the front surface and cannot be adopted as a product.
The cleaning performance evaluation results and the coefficient of friction of the photoreceptor surface after running 1 million sheets are shown in Table 1. The friction coefficient is 0.31, showing good cleaning performance, and the image after running 1 million sheets is also the initial image. Similarly, it was high definition and high image quality.

<Example 2>
A toner was obtained by operating in the same manner as in Example 1. However, after the silica fine particle dispersion was gradually added with stirring, the toner dispersion temperature was kept at 50 ° C. for 1 hour, followed by stirring, cooling to room temperature, filtration and separation, and the resulting cake was depressurized at 40 ° C. for 24 hours. The toner particles were obtained by drying. According to SEM, about 0.12 μm silica fine particles were uniformly attached to the surface of the obtained toner particles in a slightly buried form. The results of the same evaluation as in Example 1 are shown in Table 1, and showed very good cleaning properties.
<Comparative Example 1>
In place of the silica fine particle dispersion of Example 1, a solution containing no silica, that is, 0.2 parts by weight of Footent 310 (manufactured by Neos), 70 parts by weight of ion-exchanged water and 30 parts by weight of methanol was added in the same amount. Otherwise, the same procedure was followed to obtain a toner of Comparative Example 1.
The results of the same evaluation as in Example 1 are shown in Table 1, but the cleaning properties were clearly inferior to those in Example 1.
<Comparative example 2>
A toner of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that zinc stearate was removed from the external additive formulation during dry external addition.
The results of the same evaluation as in Example 1 are shown in Table 1, but the cleaning properties were considerably inferior.

<Comparative Example 3>
In Example 1, when performing the dry external addition without adding the silica X-24 to the wet external addition, the same operation was carried out except that the dry external addition was carried out together with other external additives, whereby the toner of Comparative Example 3 was obtained.
The results of the same evaluation as in Example 1 are shown in Table 1, but the cleaning properties were considerably inferior.
<Comparative example 4>
A comparative photoconductor was obtained in the same manner as in Example 1 except that the photoconductor was not provided with a protective layer containing a friction coefficient reducing substance. The surface friction coefficient of the prepared photoreceptor was 0.53.
The results of the same evaluation as in Example 1 are shown in Table 1. The friction coefficient after running 1 million sheets was high, and the cleaning performance was clearly inferior to that in Example 1.
<Comparative Example 5>
During the dry external addition of the toner of Comparative Example 1, zinc stearate was excluded from the external additive formulation, and the same procedure as in Example 1 was performed except that the protective layer containing the friction coefficient reducing substance was not provided on the photoreceptor. A comparative photoreceptor was obtained.
The results of the same evaluation as in Example 1 are shown in Table 1. However, the coefficient of friction after running 1 million sheets was very high, and the cleaning property was considerably inferior.

Based on the above results, relatively large fine particles are strongly adhered by wet external addition to the toner surface having a small particle size and high circularity, which can obtain a high-definition and high-quality image at low cost, and the surface friction coefficient is reduced. By using a low photoreceptor, it is possible to provide an image forming apparatus capable of suppressing the rotation of toner particles during cleaning and dramatically improving blade cleaning performance.
Further, by performing the heat treatment, relatively large fine particles adhering to the toner surface can be firmly adhered, and the effect can be further ensured.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. FIG. 2 is a schematic diagram illustrating a configuration of an image forming unit in the image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming unit 21 Process cartridge 3 Transfer apparatus 31 Transfer belt 5 Photoconductor (Image carrier)
6 Exposure device 7 Double-side unit 8 Reversing unit 9 Fixing device 10 Developing device 11, 12 Paper feed cassette 13 Manual feed tray 14 Charging device 141 Charging roller 142 Charging roller cleaning brush 15 Cleaning device 151 Cleaning blade 152 Blade pressure spring 153 Blade rotation Support point 154 Cleaning blade support 155 Waste toner collecting coil 158 Brush roller scraper 16 Coating device 161 Brush roller 162 Lubricant molding 163 Bar pressure spring 20 Reverse paper discharge path 25 Roller pair 26 Paper discharge trays 45a and 45b Transport guide Plate 46 Conveying rollers 55 and 56 Separating paper feeding unit 58 Paper adsorbing roller 59 Registration roller pair

Claims (6)

An image carrier for carrying a latent image;
Charging means for uniformly charging the surface of the image carrier with the AC bias voltage superimposed on the DC bias voltage;
Exposure means for exposing the surface of the charged image carrier based on image data and writing a latent image;
A developing unit that supplies a toner having a volume average particle diameter of 1 to 8 μm and an average circularity of 0.95 to 1.0 to a latent image formed on the surface of the image carrier, and visualizes the latent image;
Transfer means for transferring a visible image on the surface of the image carrier to a transfer medium;
A cleaning unit for cleaning the surface of the image carrier after transfer, the cleaning unit having a cleaning blade for removing at least toner on the image carrier;
In an image forming apparatus provided with a lubricant application unit that is disposed upstream of the cleaning blade in the rotation direction of the image carrier and applies a solid lubricant to the surface of the image carrier.
The toner is a toner obtained by wet external addition of silica fine particles having an average particle size of 0.03~1μm the base particles the surface of the toner,
An image forming apparatus, wherein the coefficient of static friction of the image carrier with respect to medium-quality high-quality paper measured by an Euler belt method is 0.1 to 0.4. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the toner is obtained by performing a heat treatment after wet external addition. The image forming apparatus according to claim 1, wherein
The toner is a toner obtained by wet external addition by adding a surfactant having a different polarity from the polar group on the surface of the toner base particles and inorganic fine particles in the aqueous medium after the emulsification dispersion step. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the toner is externally added with a fluidizing agent. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the image carrier contains a fluorine-based resin or a silicon-based resin in a surface layer. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the solid lubricant is zinc stearate.

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